EXHIBIT 10.18

                       ASSIGNMENT OF OFFICE SPACE LEASE

     For good and valuable consideration, the receipt of which is hereby
acknowledged, Drug Development Investment Corp., a Texas corporation, dba id2,
Inc., in its corporate capacity and as the sole general partner of id2-I, L.P.
("Assignor") hereby assigns, grants and conveys unto Sensus Drug Development
Corp. ("Assignee") all of Assignor's right, title and interest in and to that
certain Office Space Lease by and between San Jacinto Office Tower Limited
Partnership as Landlord and Drug Development Investment Corp. dba id2, Inc. and
id2-I, L.P. as Tenant dated March 17, 1993, as thereafter amended (the "Lease"),
for all premises covered by the Lease and located at 98 San Jacinto Center, 98
San Jacinto Blvd., Austin, Texas 78701.

     Assignee agrees to (a) assume all of Assignor's obligations as Lessor under
such Lease and its subsequent amendments, and (b) indemnify and hold Assignor
and each guarantor of the Lease harmless from and against any and all past,
present and future expenses, claims or liabilities with respect to such Lease.

     This Agreement shall be governed by the laws of the state of Texas, and may
be signed in multiple counterparts.

     Dated the 3rd day of August, 1998.

                                    ASSIGNOR:

                                    DRUG DEVELOPMENT INVESTMENT 
                                    CORP., dba id2, Inc. and as sole partner of 
                                    id2-I, L.P., a Texas limited partnership

                                    By:  /s/ John A. Scarlett
                                         --------------------
                                         Its Duly Authorized Representative

                                    ASSIGNEE:

                                    SENSUS DRUG DEVELOPMENT CORP.

                                    By:  /s/ John A. Scarlett
                                         --------------------
                                         Its Duly Authorized Representative

 
                            BASIC LEASE INFORMATION

Date of Lease:  March 17, 1993

Tenant:         Drug Development Investment Corp., a Texas corporation d/b/a 
                id2-I, L.P., a Texas limited partnership

Address of Tenant:      230 San Jacinto Center
                        98 San Jacinto Blvd.
                        Austin, TX 78701
 
Contact:        Mr. Richard J. Hawkins          Telephone:  (512) ___-____

Landlord:       San Jacinto Office Tower Limited Partnership

Address of Landlord:    300 San Jacinto Center
                        98 San Jacinto Blvd.
                        Austin, TX 78701

Contact:        Mr. Bret Messer                 Telephone:  (512) 320-5678

Premises:       Suite No. 230, which is located in the office building, commonly
                referred to as San Jacinto Center (the "Building") which has
                been constructed on the land (the "Land") located on Lot 1 of
                San Jacinto Center, an addition to the City of Austin, Texas,
                according to the Plat thereof recorded in Volume 89, Page 21 of
                the Plat Records of Travis County, Texas, which Premises are
                outlined in the plan attached hereto as Exhibit "A."

Lease Term:     The period commencing on May 1, 1993 (the "Commencement Date")
                and, subject to and upon the terms and conditions set forth in
                the Lease, or in any exhibit or addendum thereto, continuing for
                60 calendar months thereafter, unless sooner terminated;
                provided, however, if the Premises are not ready for occupancy
                for any reason other than Tenant's Delay (as defined in the
                Lease), then, as Tenant's sole and exclusive remedy, the
                Commencement Date shall be delayed one day for each day the
                Premises are not ready for occupancy; provided further, that in
                the event the Commencement Date were the first day of the next
                full calendar month and rent shall be prorated for the first
                partial month of the Lease.

Net Rentable Area of the Premises:  approximately 3,188 square feet

Base Rent:      Base Rent for the Lease Term shall be $2,324.58 per month,
                calculated at $8.75 per annum per square foot of Net Rentable
                Area of the Premises, all as adjusted pursuant to Exhibit "C"
                attached hereto and incorporated herein.

Estimate of Tenant's Occupancy Costs (as defined in the Lease) for the first
Calendar Year (as defined in the Lease):

                $1,907.49 per month, calculated at $7.18 per annum per square
                foot of Net Rentable Area of the Premises.

 
Security Deposit:  $4,232.07

Permitted Use:  Tenant shall use and occupy the Premises for business offices
                and for no other use or purpose without the prior written
                consent of Landlord.

Parking:  Subject to the terms and provisions of Rider 102 attached hereto and
          incorporated by reference herein, two reserved and three unreserved
          parking spaces shall be available to Tenant throughout the term of
          this Lease; provided, however, that Landlord shall have the right,
          from time to time throughout the Lease Term, upon 30 days' prior
          written notice to Tenant, to terminate Tenant's right to lease one of
          the aforementioned reserved parking spaces until further notice to
          Tenant that such reserved parking space is again available (if ever).
          The charge for each reserved parking space for the Lease Term shall be
          $80.00 per month payable to the garage operator no later than the
          fifth day of each month. The charge for each unreserved parking space
          for the Lease Term shall be $60.00 per month payable to the garage
          operator no later than the fifth day of each month.

This Basic Lease Information is hereby incorporated into and made a part of the
lease attached hereto (the "Lease").

Each reference in the Lease to any of the information or definitions set forth
in this Basic Lease Information shall mean and refer to the information and
definitions hereinabove set forth and shall be used in conjunction with the
provisions of the Lease.  In the event of any direct conflict between this Basic
Lease Information and the Lease, this Basic Lease Information shall control;
provided, however, that those provisions of the Lease (including its Exhibits
and Riders) which expressly require an adjustment or modification to any of the
matters set forth in this Basic Lease Information shall supersede the provisions
of this Basic Lease Information.

 
LANDLORD:                                       Tenant:
                                             
San Jacinto Office Tower Limited                DRUG DEVELOPMENT INVESTMENT CORP., 
Partnership, a Texas limited partnership        a Texas corporation d/b/a id2, Inc.
By:  Equity Assets Management, Inc., its        By: /s/ Richard J. Hawkins
     authorized agent                               -------------------------------
                                                    Name:  Richard J. Hawkins
                                                    Title: Chairman of the Board of Directors
 
     By: /s/  Richard J. Berk
         --------------------------------       Id2-I, L.P., a Texas limited partnership
         Name:  Richard J. Berk                    
         Title: Vice President
                Owner Representation
                                                By:  Drug Development Investment Corp., a
                                                     Texas corporation d/b/a id2, Inc., its sole
                                                     general partner

                                                By:  /s/ Richard J. Hawkins
                                                    -------------------------------
                                                    Name:  Richard J. Hawkins
                                                    Title: Chairman of the Board of Directors


 
                              OFFICE SPACE LEASE



                                by and between



                 SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP
                         a Texas limited partnership,
                                  as Landlord



                                      and



            DRUG DEVELOPMENT INVESTMENT CORP., a Texas corporation
                                d/b/a Id2, Inc.



                                      and



                                id2 - I. L.P.,
                          a Texas limited partnership
                                   as Tenant



                             Dated: March 17, 1993

 
                              OFFICE SPACE LEASE
                                        
     THIS OFFICE SPACE LEASE (this "Lease") is made and entered into this 17th
day of March, 1993, by and between SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP,
a Texas limited partnership (hereinafter called "Landlord"), and DRUG
DEVELOPMENT INVESTMENT CORP., a Texas corporation d/b/a id2, Inc. and id2-I,
L.P., a Texas limited partnership (hereinafter jointly called "Tenant"):

                                  WITNESSETH:

     Landlord, in consideration of the rent to be paid and the covenants and
agreements to be performed by Tenant, as hereinafter set forth, does hereby
Lease, Demise and Let unto Tenant and Tenant accepts that certain office space
containing the Net Rentable Area (as defined in Rider No. 101) provided for in
the Basic Lease Information attached hereto, located on the floor shown and
designated on the floor plan attached hereto as Exhibit "A" (the "Premises") in
Landlord's building commonly known as San Jacinto Center (the "Building")
located on Lot 1 of San Jacinto Center, an addition to the City of Austin,
Texas, according to the Plat thereof recorded in Volume 89, Page 21, of the Plat
Records of Travis County, Texas (the "Land"), for the Lease Term (as hereinafter
defined), all upon and subject to the following terms, provisions, covenants,
agreements, and conditions:

     1.   LEASE TERM.  Subject to the provisions of Paragraph 7 below, this
Lease shall commence on the date and continue for the calendar months provided
for in the Basic Lease Information.

     2.   BASE RENT.  Tenant covenants and agrees to pay Landlord in currency of
the United States of America that at the time of payment is legal tender for
payment of public and private debts, without demand, setoff or deduction
whatsoever, except as otherwise expressly provided in this Lease, the base
annual rental (the "Base Rent") as provided for in the Basic Lease Information.
Tenant shall pay the Base Rent in equal monthly installments equal to one-
twelfth (1/12th) of the product of the total square feet of Net Rentable Area in
the Premises multiplied by the rate per square foot of Net Rentable Area for the
applicable Lease Year, each in advance on the first day of each month during the
Lease Term.

     3.   ADDITIONAL RENT.

          (a) In addition to the Base Rent, Tenant also covenants and agrees to
pay as additional rent under this Lease at the times and in the manner as
hereinafter provided, an amount ("Tenant's Occupancy Costs") equal to Tenant's
Proportionate Share of Operating Costs (as such terms are defined in said Rider
No. 101).

          (b) Prior to the Commencement Date and the beginning of each Calendar
Year (as defined in said Rider No. 101) or as soon as practical thereafter,
Landlord shall compute and deliver to Tenant a bona fide estimate of Tenant's
Occupancy Costs for the respective Calendar Year and without further notice
Tenant shall pay to Landlord in monthly installments one-twelfth (1/12th) of
such estimate simultaneously with Tenant's payment of the monthly installment of
Base Rent.  For purposes of notice to Tenant hereunder, Landlord's estimate of

 
Tenant's Occupancy Costs for the first Calendar Year is as provided for in the
Basic Lease Information.

          (c) Unless delayed by causes beyond Landlord's reasonable control,
within one hundred fifty (150) days after the end of any respective Calendar
Year, Landlord shall give Tenant a written notice setting out the actual
Operating cost of the Building and Land and the actual calculation of Tenant's
Occupancy Costs incurred during the foregoing Calendar Year.  If the aggregate
of the monthly installments of the Tenant's Occupancy Costs actually paid to
Landlord during such Calendar Year differs from the amount of Tenant's Occupancy
Costs that should have been paid, then:

              (i)   If the actual costs exceed the costs paid, then Tenant
covenants and agrees to pay the difference to Landlord within ten (10) days
after receipt of the written notice from Landlord specifying the amount owed; or

              (ii)  If the costs paid exceed the actual costs, then Landlord
shall, at Landlord's option, either apply the difference as a credit against the
next maturing installments of Tenant's Occupancy Costs or reimburse such excess
amount to Tenant within ten (10) days after the Landlord's delivery of the
written notice specifying the amount owed.

     4.   PAYMENT AND PERFORMANCE.  Tenant agrees to pay all rents and sums
provided to be paid by Tenant hereunder at the times and in the manner herein
provided, without any set-off, deduction or counterclaim whatsoever, except as
otherwise expressly provided in this Lease.  Should this Lease commence on a day
other than the first day of a calendar month or terminate on a day other than
the last day of a calendar month, the rent for such partial month shall be
proportionately reduced.  The obligation of Tenant to pay such rent is an
independent covenant, and no act or circumstance whatsoever, whether such act or
circumstance constitutes a breach of covenant by Landlord or not, shall release
Tenant from the obligation to pay rent.  Time is of the essence in the
performance of all of Tenant's and Landlord's respective obligations hereunder.
Any amount which becomes owing by Tenant to Landlord hereunder shall bear
interest from the date past due until paid at an annual rate (the "Past Due
Rate") equal to the lesser of (i) five percent (5%) in excess of the prime rate
of major lending institutions published in the Wall Street Journal on the date
of Tenant's default or (ii) the maximum nonusurious rate which shall mean the
highest rate which, when multiplied times the amount owing, shall not result in
charging interest in excess of the maximum amount of interest which Landlord is
legally entitled to contract for, charge or collect under applicable state or
federal law.

     5.   SECURITY DEPOSIT.  Tenant has deposited with Landlord on the date of
the execution of this Lease the sum of $4,232.07 as security for the full and
faithful performance by Tenant of Tenant's covenants and obligations hereunder.
Such security deposit shall not bear interest and shall not be considered an
advance payment of rent or a measure or limitation of Landlord's damages in case
of default by Tenant.  In the event Tenant defaults in the performance of any of
the covenants or obligations to be performed by it hereunder, including but not
limited to the payment of all rent to be paid hereunder, Landlord may, from time
to time, without prejudice to any other remedy, use such security deposit to the
extent necessary to make good any arrearages in rent or in any sum as to which
Tenant is in default or otherwise obligated to pay hereunder and to pay for any
other damages, injury, expense, or liability caused to 

 
Landlord by such default, including any damages or deficiency in the reletting
of the Premises, whether such damages or deficiency may accrue before or after
termination of this Lease. Following any such application of the security
deposit, Tenant shall pay and be obligated to pay to Landlord on demand the
amount so applied in order to restore the security deposit to its original
amount. Landlord may commingle such security deposit with Landlord's other
funds. If Tenant is not then in default hereunder on the date which this Lease
is terminated, any remaining balance of the security deposit shall be returned
by Landlord to Tenant upon termination of this Lease and after delivery by
Tenant of possession of the Premises to Landlord in accordance with the terms
and conditions of this Lease. Notwithstanding the foregoing, Landlord has
collaterally assigned its interest in the Premises during the Lease Term,
including the security deposit, to Manufacturers Hanover Trust Company, its
successors and assigns ("Lender"), and Landlord's liability for the return of
such security deposit is expressly subject to Lender's consent to and release of
such security deposit, and Tenant agrees to look solely to Lender and the terms
of any Subordination, Nondisturbance and Attornment Agreement entered into with
Lender for the return of such security deposit.

     6.   INSTALLATION OF IMPROVEMENTS.  Landlord has made no representations or
warranties as to the condition of the Premises, the Building or the Land, nor
has Landlord made any commitments to remodel, repair or redecorate except as
expressly set forth in the Work Letter attached hereto as Exhibit "D" and made a
part hereof for all purposes.  Landlord will install or cause to be installed in
the Premises all improvements shown on the Work Letter upon the terms and
conditions set forth in the Work Letter.  Otherwise, Tenant acknowledges that
Tenant is accepting the Premises on an "as is" basis.

     7.   COMPLETION OF IMPROVEMENTS AND COMMENCEMENT DATE.  If the Premises are
not ready for occupancy by Tenant on the Commencement Date, the obligations of
Landlord and Tenant shall nevertheless continue in full force and effect,
including the obligation of Tenant to commence paying rent on the Commencement
Date provided that if the Premises are not ready for occupancy for any reason
other than Tenant's Delay (as defined in Exhibit "D" attached hereto), then the
rent shall abate and not commence or become due until the date that the
leasehold improvements to the Premises are Substantially Complete (as
hereinafter defined).  Any such abatement of rent, however, shall constitute
full settlement of all claims that Tenant may otherwise have against Landlord by
reason of the Premises not being ready for occupancy by Tenant on the
Commencement Date.  Notwithstanding the foregoing, if Tenant, with Landlord's
consent, occupies the Premises after the Premises are Substantially Complete but
prior to the beginning of the Lease Term, all of the terms and provisions of
this Lease shall be in full force and effect from the commencement of such
occupancy, and the Lease Term shall commence on the date on which Tenant first
occupies the Premises (which date shall be deemed to be the Commencement Date
hereunder) and shall expire the same period of months after the Commencement
Date as set forth in Paragraph 1 above; and no change shall occur in the length
of the Lease Term.  By moving into the Premises or taking possession thereof,
Tenant accepts the Premises as suitable for the purposes for which the same are
leased and accepts the Building and each and every appurtenance thereof, and
waives any and all defects therein; provided, however, that it is agreed that
Tenant shall have the right to accept the Premises after moving therein or
taking possession thereof subject to the punch list described or referred to in
Exhibit "C-1" attached hereto, and Landlord and Tenant shall promptly execute
and delivery, each to the other, an Acceptance of Premises Memorandum, the form
of which is attached hereto as Exhibit 

 
"C" and made a part hereof for all purposes. For the purposes hereof, the term
"Substantially Complete" shall mean the first to occur of the following:

          (a) the date Landlord substantially completes the work required of it
under the terms of the Work Letter being executed contemporaneously herewith the
form of which is attached hereto as Exhibit "D"; or

          (b) the Date Landlord would have substantially completed the work
required of it under the terms of the aforesaid Work Letter but for Tenant's
Delay; or

          (c) the date Tenant takes possession of the Premises.

     If for any reason a dispute arises as to any of the dates described above,
a certificate furnished by Landlord's architect or space planner certifying the
date on which the Premises were Substantially Complete, shall be conclusive and
binding upon the parties hereto.

     8.   LANDLORD'S OBLIGATIONS.  So long as Tenant is not in default under
this Lease, Landlord agrees to furnish facilities to provide for the following
services:

          (a) air conditioning, both heating and cooling (as required by the
seasons), from 7:00 a.m. to 7:00 p.m. on weekdays and on Saturdays from 8:00
a.m. to 1:00 p.m. (except on legal holidays designated in the Building Rules and
Regulations) and at such temperatures and in such amount as may in the sole
judgment of Landlord be reasonably required for comfortable use and occupancy
under normal business operations; provided, that circulating air will not be
available other than by air conditioning and if Tenant shall require air
conditioning at any time other than the hours and the days above specified,
Landlord shall furnish the same upon a written request of Tenant delivered to
the Building management office before 3:00 p.m. of the business day of the extra
usage, and for such service Tenant shall pay Landlord as additional rent within
ten (10) days after receipt of a bill therefor, the sum of $25.00 per hour per
air handler unit (subject to adjustments to reflect increases in labor and
utility costs as reasonably determined by Landlord);

          (b) hot and cold water supplied from the regular supply of water to
the Building at points of supply provided for general use of tenants of the
Building through fixtures installed by Landlord or by Tenant with Landlord's
prior written consent;

          (c) janitor service to the Premises on weekdays other than holidays
and such window washing and wall cleaning as may in the judgment of Landlord be
reasonably required;

          (d) automatic passenger elevators where applicable, provided that
Landlord may reasonably limit the number of elevators to be in operation on
Saturdays,, Sundays, holidays and before and after normal business hours, as
further set forth in the Building Rules and Regulations;

          (e) freight elevator service in common with other tenants but only
when scheduled through the Building management office;

          (f)  restroom facilities;

 
          (g) electric lighting for all public areas and special service areas
of the Building in the manner and to the extent deemed by Landlord to be
reasonable; and

          (h) replacement of Building standard lighting tubes.

     9.   ELECTRICAL USAGE.  Landlord shall furnish sufficient power for (a)
lighting, (b) typewriters, voice writers, calculating machines, and other
standard office machines of similar low electrical consumption, (c) desktop
computers, facsimiles, printers, reprographic [provided however that if the
foregoing equipment in this subsection (c) requires a dedicated circuit, Tenant
shall pay to Landlord all costs associated with the installation, repair and
maintenance of such dedicated circuit], and (d) electricity for electronic data
processing equipment, special lighting in excess of Building standard, or any
equipment or machines not standard office machines or which, in any event,
require a nominal voltage of more than 120 volts single phase; provided,
however, Tenant shall give Landlord written notice prior to placing any
equipment, machines, or special lighting in the Premises which may consume in
excess of such normal low usage machines, and Landlord, at Tenant's expense to
be reimbursed to Landlord as additional rent upon demand, will make reasonable
efforts to supply such service through the then existing feeders servicing the
Building.  Tenant shall pay not only Tenant's Proportionate Share (as defined in
Rider No. 101 attached hereto) of the cost of the standard electricity furnished
to the Building, but also, upon demand and receipt by Tenant of reasonable
documentation, the total cost of any of Tenant's consumption in excess of those
normal office machine requirements.  If Tenant has any equipment or machines
that require such excess amounts of electricity, Landlord reserves the right, at
its sole option, to install a submeter(s), at Tenant's expense to be reimbursed
to Landlord as additional rent upon demand, for the Premises or any part or
parts thereof.  If Tenant has excess electricity requirements for which Landlord
does not elect to install submeter(s), Landlord's engineer shall determine the
amount of excess electricity to be allocated to Tenant based on the power
requirements of any such equipment, machines, or special lighting.  Whenever
heat-generating machines or equipment (other than such standard office machines)
which effect the temperatures otherwise maintained by the air conditioning
system, are used in the Premises by Tenant, Landlord shall have the right to
install supplemental air conditioning units in the Premises, and the cost
thereof, including the cost of installation, operation, use and maintenance,
shall be paid as additional rent by Tenant to Landlord on demand.  Any riser or
risers or wiring to meet Tenant's excess electrical requirements will be
installed by Landlord upon written request of Tenant, at the sole cost and
expense of Tenant to be reimbursed to Landlord as additional rent upon demand,
if, in Landlord's sole judgment, the same are necessary and will not cause
permanent damage or injury to the Building or the Premises or cause or create a
dangerous or hazardous condition or entail excessive or unreasonable
alterations, repair, or expenses, or interfere with or disturb other tenants or
occupants.

     10.  SERVICE INTERRUPTIONS.  Landlord does not warrant that any of the
services provided for in Paragraphs 8 and 9 above will be free from any slow-
down, fluctuation, interruption, or stoppage nor from any change in quality,
character, or availability resulting from causes beyond the reasonable control
of Landlord or from any voluntary agreements between Landlord and any
governmental bodies or regulatory agencies, or from the maintenance, repair,
substitutions, or replacement of the equipment furnishing such service, and
specifically, no such slow-down, interruption, stoppage or change shall ever be
construed as an eviction, actual or 

 
constructive, of Tenant nor shall same cause any abatement of the rent payable
hereunder or in any manner or for any purpose relieve Tenant from any of its
obligations hereunder, and in no event shall Landlord be liable for loss or
damage to persons or property, or in default hereunder, as a result thereof.
Landlord agrees to use reasonable diligence to resume the affected service.
Notwithstanding the foregoing, in the event of the failure to furnish, any
stoppage of or other interruption in the furnishing of the services or utilities
described in Paragraphs 8 and 9 above which continues for five (5) consecutive
business days after receipt by Landlord of written notice thereof from Tenant,
and such failure, stoppage or interruption is not caused by Force Majeure (as
hereinafter defined), a casualty covered by Paragraph 18 below, a failure on the
part of a public utility, or by any act or omission of Tenant, its agents,
employees or contractors. Tenant shall be entitled, as its sole and exclusive
remedy, to an abatement of Base Rent and Tenant's Occupancy Costs in proportion
to the untenantability of the Premises caused by such failure, stoppage or
interruption, with such abatement to begin on the sixth (6th) consecutive
business day after the receipt by Landlord of written notice of such occurrence
and continuing until such failure, stoppage or interruption has been cured.

     11.  ASSIGNMENT AND SUBLETTING.

          (a) In the event Tenant should desire to assign this Lease or sublet
the Premises or any part thereof, Tenant shall give Landlord written notice of
such desire at least sixty (60) days in advance of the date on which Tenant
desires to make such assignment or sublease, which notice shall contain the name
of the proposed assignee or subtenant and the nature and character of the
business of the proposed assignee or subtenant, the term, use, rental rate and
other particulars of the proposed subletting or assignment, including without
limitation, evidence satisfactory to Landlord that the proposed subtenant or
assignee is financially responsible and will immediately occupy and thereafter
use the Premises (or any sublet portion thereof) for the remainder of the Lease
Term (or for the entire term of the sublease, if shorter).  Landlord shall then
have a period of thirty (30) days following receipt of such notice within which
to notify Tenant in writing that Landlord elects (1) to terminate this Lease as
to the space so affected as of the date so specified by Tenant for such
assignment or subletting, or (2) to permit Tenant to assign this Lease or sublet
such space, or (3) if, in Landlord's good faith judgment, such proposed assignee
or subtenant does not meet Landlord's then current requirements for new tenants
of comparable space in the Building, to refuse to consent to Tenant's assignment
or subleasing of such space and to continue this Lease in full force and effect
as to the entire Premises.  If Landlord shall fail to notify Tenant in writing
of such election within said thirty (30) day period, Landlord shall be deemed to
have elected option (3) above.  If Landlord consents to an assignment or
sublease, Tenant agrees to provide, at its expense, direct access from the
assignment or subletting upon Tenant's payment to Landlord of any reasonable
costs incurred by Landlord in reviewing and approving such requested assignment
or subletting, including, without limitation, Landlord's attorneys' fees.  No
assignment or subletting by Tenant shall relieve Tenant of any obligations under
this Lease.  Consent of Landlord to a particular assignment or sublease or other
transaction shall not be deemed a consent to any other or subsequent
transaction.  Without limiting the foregoing, any refusal by Landlord to consent
to any assignment or sublease shall be deemed a reasonable withholding of
Landlord's consent in the event of the refusal or failure of any mortgage, deed
of trust holder or other secured party so entitled, to consent to such
assignment or sublease.

 
          (b) If Landlord consents to any subletting or assignment by Tenant as
herein above provided, and subsequently any rents received by Tenant under any
such sublease are in excess of the rent payable by Tenant to Landlord or Tenant
receives any additional consideration from the assignee under any such
assignment, then Landlord may, at its option, either (1) declare such excess
rents under any sublease or such additional consideration for any assignment to
be due and payable by Tenant to Landlord as additional rent hereunder, or (2)
elect to cancel this Lease as to the space assigned or sublet and at Landlord's
option, enter into a lease directly with such assignee or subtenant, without
liability to Tenant.

          (c) Landlord shall have the right to transfer and assign, in whole or
in part, all its rights and obligations hereunder and in the Building and
property referred to herein, and in such event and upon assumption by the
transferee of Landlord's obligations hereunder (any such transferee to have the
benefit of, and be subject to, the provisions of this Lease) no further
liability or obligation shall thereafter accrue against Landlord hereunder.

          (d) No assignment or sublease shall release Tenant or Tenant's
guarantor from any obligations hereunder.  In the event Tenant is in default
under any of the terms or conditions of this Lease, then Landlord, in addition
to any other remedies, may collect all rents coming due directly from any
subtenant and apply same against any sums due Landlord by Tenant, but Tenant
shall not be released from any further liability or obligations because of such
collections by Landlord, except to the extent of the amount of rents actually
received by Landlord from any subtenant.  A consent to one sublease or
assignment shall not be considered a consent to any future subleases or
assignments.

          (e) If Tenant is a corporation and if at any time during the Lease
Term the person or persons who own the voting shares at the time of the
execution of this Lease cease for any reason, including but not limited to
merger, consolidation or other reorganization involving another corporation, to
own a majority of such shares, or if Tenant is a partnership and if at any time
during the Lease Term the general partner or partners who own the general
partnership interests in the partnership at the time of the execution of this
Lease cease for any reason to own a majority of such interests (except as the
result of transfers by gift, bequest or inheritance to or for the benefit of
members of the immediate family of such original shareholder(s) or partner(s)),
such an event shall be deemed to be an assignment requiring Tenant to comply
with the terms hereof.  The preceding sentence shall not apply whenever Tenant
is a corporation the outstanding stock of which is listed on a recognized
security exchange, or if at least eighty percent (80%) of its voting stock is
owned by another corporation, the voting stock of which is so listed.

          (f) Tenant shall not mortgage, pledge, or otherwise encumber its
interest in this Lease or in the Premises.

     12.  USE AND OCCUPANCY.  Tenant (and its permitted assignees and
subtenants) covenants and agrees that the Premises shall be used and occupied by
Tenant only for the Permitted Use set forth in the Basic Lease Information and
for no other purpose, and Tenant agrees to use and maintain the Premises in a
clean, careful, safe, and proper manner and to comply with all applicable laws,
ordinances, orders, rules, and regulations of all governmental bodies (state,
federal and municipal).  Tenant agrees not to commit waste nor suffer or permit
waste to be committed or to allow or permit any nuisance on or in the Premises
nor will Tenant 

 
use the Premises for any purposes, directly or indirectly, that are forbidden by
law, ordinance, governmental or municipal regulation or ordinance or which are
dangerous to life, limb or property or for lodging or sleeping purposes. Tenant
will conduct its business and occupy the Premises and will control its agents,
employees, licensees, and invitees in such a manner so as not to create any
nuisance or interfere with, annoy, or disturb any of the other tenants in the
Building or Landlord in its management of the Building and so as not to injure
the reputation of the Building. Tenant shall not use the Premises or allow or
permit same to be used in any way or for any purpose that Landlord may deem to
be extra hazardous on account of the possibility of fire or other casualty or
which will increase the rate of fire or other insurance for the Building or its
contents or which may render the Building uninsurable at normal rates by
responsible insurance carriers authorized to do business in the State of Texas,
or which may render void or voidable any insurance on the Building and, in the
event that there are increased insurance premiums because of Tenant's use of the
Premises, then, in addition to any other remedies Landlord may have hereunder,
Tenant shall pay such increase to Landlord within ten (10) days of being billed
by Landlord, provided that such bill from Landlord shall include a copy of
premium notices or other documents supplied by the insurer identifying
specifically the use of the Premises by Tenant causing the increased insurance
premium and specifically identifying the dollar amount of that increase. Tenant
shall not erect, place, or allow to be placed any sign, advertising matter,
stand, booth, or showcase in or upon the doorsteps, vestibules, halls,
corridors, doors, walls, windows, or pavement of the Building or the Land
(except for lettering on the door or doors to the Premises as allowed by the
Rules and Regulations attached hereto as Exhibit "B") without the prior written
consent of Landlord.

     13.  ALTERATIONS AND ADDITIONS BY TENANT.  Tenant shall not make or allow
to be made any alterations, improvements, or additions in or to the Premises
without first obtaining the written consent of Landlord, and all alterations,
additions, and improvements made to or fixtures or other improvements placed in
or upon the Premises, whether temporary or permanent in character, by either
party (except only moveable office furniture and equipment not attached to the
Building) shall be deemed a part of the Building and with respect to Tenant's
alterations, additions, improvements, and fixtures, they shall remain Tenant's
property until the expiration or earlier termination of the Lease at which time
they shall become the property of Landlord without compensation to Tenant.
Alterations, improvements, and additions in and to the Premises requested by
Tenant shall be in accordance with plans and specifications which have been
previously submitted to and approved in writing by Landlord.  Such work shall be
performed at Tenant's expense and accomplished either by Landlord or by
contractors and subcontractors approved in writing by Landlord.  If such work is
performed by Landlord, Landlord shall be entitled to a construction supervision
fee in the amount of five percent (5%) of the cost of any alterations,
improvements or additions made by Landlord in or to the Premises at the request
of Tenant.  If such work is not performed by Landlord, then all work performed
by other contractors and subcontractors shall be subject to the following
conditions:

          (a) A certificate of insurance for each contractor and subcontractor
must be submitted to the Landlord for approval prior to commencement of
construction.

          (b) Tenant shall insure that all workmen will be cooperative with
Building personnel and comply with all Building rules and regulations.

 
          (c) All construction shall be done in a good and workmanlike manner
and shall be subject to approval by Landlord upon completion, which approval
shall not be withheld unreasonably.

          (d) Lien releases in recordable form from each contractor and
subcontractor must be submitted to the Landlord within five (5) days after
completion.

          (e) All construction shall comply with all applicable governmental
laws, rules and regulations.

     14.  REPAIR AND MAINTENANCE BY TENANT.  Tenant will not in any manner
deface or damage the Building or Land and will pay, as additional rent, on
demand, the cost of replacing any damage done to the Building or Land or any
part thereof by Tenant or Tenant's agents, employees, contractors or invitees.
Except to the extent Landlord is expressly so obligated hereunder, Tenant shall
keep the Premises including all fixtures and improvements installed by or for
Tenant in good and tenantable condition and shall promptly make all necessary
non-structural repairs and replacements thereto except those caused by fire or
other casualty covered by Landlord's insurance on the Building, all at Tenant's
sole expense, under the supervision and with the approval of Landlord.  Said
repairs and replacements shall be equal  in quality and class to the original
work.  Without diminishing such obligation of Tenant and in addition to any
other remedies Landlord may have, if Tenant fails to make such repairs and
replacements within fifteen (15) days after the occurrence of the damage or
injury, Landlord may at its option make such repairs and replacements and Tenant
shall pay Landlord the cost there of as additional rental hereunder upon demand.

     15.  MECHANIC'S LIENS.  Tenant will not permit any mechanic's or
materialman's lien or liens to be placed upon the Premises or improvements
thereon or the Building or Land during the term hereof caused by or resulting
from any work performed, materials furnished or obligations incurred by or at
the request of Tenant and nothing in this Lease contained shall be deemed or
construed in any way as constituting the consent or request of Landlord, express
or implied, by inference or otherwise, to any contractor, subcontractor, laborer
or materialman for the performance of any labor or the furnishing of any
materials that would give rise to the filing of any mechanic's, materialman's,
or other liens against the interest of Landlord in the Building, the Land or the
Premises.  In the case of the filing of any such mechanic's and materialman's
lien on the interest of Landlord or Tenant in the Premises or the Building or
Land resulting from work performed, materials furnished or obligations incurred
by or at the request of Tenant, Tenant shall cause the same to be discharged of
record or adequately bonded around within twenty (20) days after the filing of
same.  If Tenant shall fail to discharge or adequately bond around such lien
within such period, then, in addition to any other right or remedy of Landlord,
Landlord may, but shall not be obligated to, discharge the same either by paying
the amount claimed to be due or by procuring the discharge of such lien by
deposit in court or bonding.  Any amount paid by Landlord for any of the
aforesaid purposes, together with all reasonable legal and other expenses of
Landlord in defending any such action or procuring the discharge of such lien,
shall be paid by Tenant to Landlord as additional rent on demand.

     16.  INDEMNITY AND NON-LIABILITY.  Landlord will not be liable for and
Tenant will indemnify and hold Landlord harmless from all suite, liability,
fines, claims, demands, actions, 

 
damages, losses, costs and expense, including, but not limited to, Landlord's
reasonable attorney's fees for any injury or death to persons, any loss or
damage to property, or any loss of or damage to Tenant's business caused wholly
or in part by (i) the negligence of, (ii) an act, omission or misconduct of,
(iii) a breach of this Lease by or (iv) the use or occupancy of the Premises by,
Tenant, its employees, agents, servants, contractors, licensees, invitees or
subtenants. If Landlord shall, without fault on its part, be made a party to any
action commenced by or against Tenant, Tenant shall protect, indemnify and hold
Landlord harmless therefrom and shall pay to Landlord all costs, expenses, and
reasonable attorneys' fees incurred by Landlord in connection therewith. Unless
caused by the negligence or willful misconduct of Landlord, Landlord shall not
be liable or responsible for any loss or damage to property or death or injury
to persons occasioned by theft, fire, act of God, injunction, riot, strike, war,
court order, other governmental action or other matters beyond the control of
Landlord, or by or through the acts, misconduct or omissions of other tenants,
or by the Building or its improvements becoming out of repair, or the leakage or
failure of any pipes, wiring or fixtures, or the backing up of any drains. The
provisions of this Paragraph shall survive the expiration or earlier termination
of this Lease.

     17.  CERTAIN RIGHTS RESERVED BY LANDLORD.  Landlord shall have the
following rights, exercisable without notice [except with respect to
subparagraphs (e) and (g)] and without liability to Tenant for damage or injury
to property, persons, or business and without effecting an eviction,
constructive or actual, or disturbance of Tenant's use or possession or giving
rise to any claim for setoff or abatement of rent:

          (a) To change the Building's name or street address.

          (b) To install, affix, and maintain any and all signs on the exterior
and interior of the Building.

          (c) To designate and approve, prior to installation, all types of
window shades, blinds, drapes, awnings, window ventilators, and similar
equipment, and to control all internal lighting that may be visible from the
exterior of the Building.

          (d) To designate, restrict, and control all sources within the
Building from which Tenant may obtain food and beverages or other services.

          (e) To enter upon the Premises at reasonable hours to exercise its
rights hereunder or inspect same or clean or make repairs or alterations (but
without any obligation to do so, except as expressly provided for herein) or to
show the Premises to prospective lenders or purchasers, and, during the last
nine (9) months of the Lease Term, to show them to prospective tenants at
reasonable hours and, if they are vacated, to prepare them for reoccupancy.

          (f) To retain at all times, and to use in case of emergency or
catastrophe, at the request of Tenant, or to exercise rights or discharge
obligations specifically granted to landlord elsewhere in this Lease, keys to
all doors within and into the Premises.  No locks shall be changed or added
without the prior written consent of Landlord.

          (g) To decorate and to make repairs, alterations, additions, changes,
or improvements, whether structural or otherwise, in and about the Building, or
any other part 

 
thereof, and for such purposes to enter upon the Premises and, during the
continuance of any of said work, to temporarily close doors, entryways, public
space, and corridors in the Building, to interrupt or temporarily suspend
Building services and facilities and to change the arrangement and location of
entrances or passageways, doors and doorways, corridors, elevators, stairs,
toilets, or other public parts of the Building, all without abatement of rent or
affecting any of Tenant's obligations hereunder, so long as access to the
Premises is not unreasonably restricted.

          (h) To have and retain paramount title to the Premises free and clear
of any act of Tenant purporting to burden or encumber such premises.

          (i) To grant to anyone the exclusive right to conduct any specific
type of business or render any specific type of service in or to the Building.

          (j) To approve the weight, size, and location of safes and other heavy
equipment and articles in and about the Premises and the Building and to require
all such items and all furniture and similar items to be moved into and out of
the Building and Premises only at such times and in such manner as Landlord
shall direct in writing.  Movements of Tenant's property into or out of the
Building and within the Building are entirely at the risk and responsibility of
Tenant.

          (k) To prohibit the placing of vending or dispensing machines of any
kind in or about the Premises without the prior written permission of Landlord.

          (l) To take all such reasonable measures as Landlord may deem
advisable for the security of the Building and its occupants, including without
limitation, the search of all persons entering or leaving the Building, the
evacuation of the Building for cause, suspected cause, or for drill purposes,
the temporary denial of access to the Building, and the closing of the Building
after regular working hours, on business days and on Sundays, and legal
holidays, subject, however, to Tenant's right to admittance when the Building is
closed after regular working hours under such reasonable regulations as Landlord
may prescribe from time to time which may include by way of example but not of
limitation, that persons entering or leaving the Building, whether or not during
regular working hours, identify themselves to a security officer by registration
or otherwise and that said persons establish their right to enter or leave the
Building.  Notwithstanding the foregoing, Landlord shall not be obligated to
provide any of the above security measures and Landlord shall not be liable to
Tenant or Tenant's employees, customers or invitees for any damages, costs or
expenses which occur for any reason in the event such security measures are not
properly installed, monitored or maintained or any such services are not
property provided, nor shall Landlord be liable to Tenant or Tenant's employees,
customers or invitees for any damages or losses caused by theft, burglary,
assault, vandalism or other crimes.  Landlord strongly encourages Tenant to
secure Tenant's own insurance, in excess of the amount required elsewhere in
this Lease, and/or to provide Tenant's own security measures, to protect against
the above occurrences if Tenant desires additional coverage for such risks.

     18.  FIRE OR OTHER CASUALTY.  If the Premises or any part thereof shall be
damaged by fire or other casualty, Tenant shall give prompt written notice
thereof to Landlord.  In case the Building shall be so damaged by fire or other
casualty that substantial alteration or reconstruction 

 
of the Building shall, in Landlord's sole opinion, be required (whether or not
the Premises shall have been damaged by such fire or other casualty) or in the
event there is less than two (2) years of the Lease Term remaining or in the
event any mortgagee under a mortgage or deed of trust covering the Building
should require that the material uninsured loss to the Building, Landlord may,
at its option, terminate this Lease and the term and estate hereby granted by
notifying Tenant in writing of such termination within sixty (60) days after the
date of such damage, in which event the rent hereunder shall be abated as of the
date of such damage. If Landlord does not thus elect to terminate this Lease,
Landlord shall within seventy-five (75) days after the date of such damage
commence to repair and restore the Building and shall proceed with reasonable
diligence to restore the Building (except that Landlord shall not be responsible
for delays outside its control) to substantially the same condition in which it
was immediately prior to the happening of the casualty, except that Landlord
shall not be required to rebuild, repair, or replace any part of Tenant's
furniture or furnishings or of fixtures and equipment owned or removable by
Tenant under the provisions of the Lease. Notwithstanding the foregoing,
Landlord's obligation to restore the Building shall not require Landlord to
expend for such repair and restoration work more than the insurance proceeds
actually received by the Landlord as a result of the casualty. Landlord shall
not be liable for any inconvenience or annoyance to Tenant or injury to the
business of Tenant resulting in any way from such damage or the repair thereof;
except that during the time and to the extent that the Premises are unfit for
occupancy, the Landlord shall, at its option, either furnish the Tenant with
comparable office space at prevailing market rates or a fair diminution of rent,
the choice of which will be at the Landlord's sole discretion. Any insurance
which may be carried by Landlord or Tenant against loss or damage to the
Building or to the Premises shall be for the sole benefit of the party carrying
such insurance and under its sole control. If the Premises or any other portion
of the Building is damaged by fire or other casualty resulting from the fault or
negligence of Tenant or any of Tenant's agents, employees, or invitees, the rent
hereunder shall not be diminished nor shall Landlord have any obligation to
furnish Tenant with comparable office space during the repair of such damage,
and Tenant shall be liable to Landlord for the cost of the repair and
restoration of the Building caused thereby to the extent such cost and expense
is not covered by insurance proceeds.

     19.  CONDEMNATION.  If all of the Building and Land or the Premises, or so
much of either as would materially interfere with Tenant's use of the remainder,
shall be taken for any public or quasi-public use under any governmental law,
ordinance or regulation or by right of eminent domain or should be sold to the
condemning authority in lieu of condemnation or, if any taking would materially
interfere with the use of the Building, Land or the Premises for the purposes
for which they are then being used, then this Lease shall terminate as of the
date when physical possession of the Building and Land or the Premises is taken
by the condemning authority.  If less than the whole or a material part of the
Building and Land or the Premises is thus taken or sold and there is no such
material interference, then Landlord shall have the option to terminate this
Lease effective as of the date title shall vest in the condemnor or transferee.
In the event this Lease is to be terminated as a result of a total or a partial
condemnation as described in this Paragraph, Tenant shall have the right to
vacate the Premises at any time within sixty (60) days preceding the date that
title vests in or physical possession is taken by the condemning authority, and
this Lease shall terminate as of the date such vacation by Tenant is complete.
The rent payable hereunder shall be diminished by an amount representing that
part of said rent as shall properly be allocable to the portion of the Premises
which was so taken or sold, 

 
provided that if this Lease has been terminated pursuant to this Paragraph 19,
Tenant's obligations under this Lease otherwise accruing after such termination
date shall cease and come to an end. Landlord shall receive the entire award
from any taking or condemnation (or the entire compensation paid because of any
transfer by agreement), and Tenant shall have no claim thereto, provided that
Tenant may apply for and retain any separate award attributable to (a)
interference with Tenant's business, (b) the cost of Tenant's relocation and (c)
the unamortized value (amortized evenly over the Lease Term) of leasehold
improvements paid for by Tenant without reimbursement from Landlord ("Tenant's
Costs"), so long as Tenant provides Landlord with written evidence of Tenant's
Costs within thirty (30) days after the Commencement Date.

     20.  TAXES ON TENANT'S PROPERTY.  Tenant shall be liable for all taxes
levied or assessed against Tenant's personal property, furniture, alterations,
improvements, or fixtures in the Premises including any sales and use taxes
associated with materials and/or services in connection with the Premises.  If
any such taxes for which Tenant is liable are levied or assessed against
Landlord or Landlord's property and if Landlord elects or is required to pay the
same or if the assessed value of Landlord's property is increased by inclusion
of Tenant's personal property, furniture, alterations, improvements or fixtures
in the Premises for which Tenant is liable hereunder, provided that Landlord
first shall provide to Tenant evidence reasonably sufficient to show that the
increase in taxes is attributable to the inclusion of Tenant's personal
property, furniture, alterations, improvements or fixtures in the Premises.

     21.  WAIVER OF SUBROGATION AND INSURANCE.

          (a) Each party hereto waives any and every claim which arises or may
arise in its favor and against the other party hereto, or anyone claiming
through or under them, by way of subrogation or otherwise, for any and all loss
of, or damage to, any of its property (whether or not such loss or damage is
caused by the fault or negligence of the other party or anyone for whom said
other party may be responsible), which loss or damage is covered (or, with
respect to loss of or damage to any of Tenant's property, could have been
covered by fire and extended coverage insurance covering Tenant's personal
property and moveable trade fixtures in the Premises to the extent of full
replacement value) by valid and collectible fire and extended coverage insurance
policies, to the extent that such loss or damage is insurable under said
insurance policies.  Said waivers shall be in addition to, and not in limitation
or derogation of, any other waiver or release contained in this Lease with
respect to any loss or damage to property of the parties hereto.  In the event
that Tenant is permitted to and self-insures any risk which would have been
covered by the insurance required to be carried by Tenant pursuant to Section
21(b) of this Lease, or if Tenant fails to carry any insurance required to be
carried by Tenant pursuant to Section 21(b) of this Lease, then all loss or
damage to Tenant, its leasehold interest, its business, its property, the
Premises or any additions or improvements thereto or contents thereof shall be
deemed covered by and recoverable by Tenant under valid and collectible policies
of insurance.

          (b) Tenant shall at its sole cost and expense, procure and maintain
through the term of this Lease a policy or policies of insurance insuring Tenant
against any and all liability for injury to or death of a person or persons and
for damage to or destruction of property occasioned by or arising out of or in
connection with the use or occupancy of the Premises or by 

 
the condition of the Premises (including the contractual liability of Tenant to
indemnify Landlord contained herein) with a combined single limit of $1,000,000
for bodily injury and/or property damages, and Tenant shall provide Landlord
with evidence thereof. All insurance shall be written by an insurance company or
companies satisfactory to Landlord and licensed to do business in the State of
Texas with Landlord and any other party in interest from time to time designated
by Landlord named as additional insiders without restriction. If Tenant has an
umbrella or excess policy, Tenant will name Landlord as an additional insured
without restriction on all layers of umbrella or excess policies. Tenant shall
obtain a written obligation on the part of each insurance company to notify
Landlord at least ten (10) days prior to cancellation of such insurance. Such
policies or duly executed certificates of insurance relating thereto shall be
promptly delivered to Landlord within five (5) days after the execution of this
Lease and renewals thereof as required shall be delivered to Landlord at least
thirty (30) days prior to the expiration of the respective policy terms. If
Tenant fails to comply with the foregoing requirements relating to insurance,
Landlord may, at its sole option, obtain such insurance and Tenant shall pay as
additional rent to Landlord on demand the premium cost thereof.

          (c) Landlord shall maintain at the expense of Landlord, (i) fire and
extended coverage insurance on the base building portion of the Building
Standard (as defined in Exhibit "D") improvements located in the Premises in
amounts reasonably determined by Landlord to cover the replacement value of such
components of the Building and (ii) comprehensive general liability insurance in
the amount of not less than $500,000 in respect of personal injury or death in
respect of any one occurrence and of not less than $100,000 for property damage
in any one occurrence.  Said insurance shall be issued by a reputable insurance
company authorized to do business in Texas.

     22.  SURRENDER UPON TERMINATION.  At the expiration or termination of this
Lease, whether caused by lapse of time or otherwise.  Tenant shall at once
remove all furniture, movable trade fixtures and equipment, and surrender
possession of the Premises and deliver the Premises to Landlord in as good
repair and condition as the commencement of Tenant's occupancy, reasonable wear
and tear and damages or destruction by fire or other insured casualty expected,
and shall deliver to Landlord all keys to the Premises.  All furniture, movable
trade fixtures and equipment shall be removed in a good and workmanlike manner
so as not to damage the Premises or the Building or the structural qualities of
the Building or the plumbing, electrical lines, or other utilities.  Tenant, or
Landlord at Tenant's expense, shall repair any damage to the Premises or the
Building and Land caused by such removal.  All furniture, movable trade fixtures
and equipment installed by Tenant not removed at the expiration of this Lease or
within fifteen (15) days after any other termination shall thereupon be
conclusively presumed to have been abandoned by Tenant and Landlord may, at its
option, take over the possession of such property and either:

          (a) Declare same to be the property of Landlord by written notice
thereof to Tenant; or

          (b) At the sole risk, cost, and expense of Tenant remove the same or
any part thereof in any manner that Landlord shall choose and store or dispose
of the same without incurring liability to Tenant or any other person.

 
     Nothing contained in this Paragraph 22 shall prejudice or impair Landlord's
rights as a lienholder and secured party under Paragraph 27 hereof, and the
rights granted to Landlord under this Paragraph 22 shall be cumulative of its
rights as lienholder and secured party.

     23.  EVENTS OF DEFAULT.

          (a) The following events shall be deemed to be events of default by
Tenant under this Lease:

              (i)   Tenant shall fail to pay when due hereunder any installment
of the rent hereby reserved or any other sum of money payable by Tenant to
Landlord; or

              (ii)  Tenant shall fail to comply with or observe any other term,
provision, or covenant of this Lease, and Tenant has not cured such failure
(except for the failure to pay rent) within twenty (20) days after the
occurrence of such failure; or

              (iii) Tenant or any guarantor of Tenant's obligations hereunder
(hereinafter called "Guarantor") shall make a transfer in fraud of creditors, or
shall make an assignment for the benefit of creditors, or Tenant or any
Guarantor shall admit in writing its inability to pay its debts as they become
due; or

              (iv)  Tenant or any Guarantor shall file a petition under any
section or chapter of the Bankruptcy Reform Act of 1978, as amended, or under
any similar law or statute of the United States or any State thereof, or Tenant
or any Guarantor shall be adjudged bankrupt or insolvent in proceedings failed
against Tenant or any Guarantor thereunder; or a petition or answer proposing
the adjudication of Tenant or any Guarantor as a bankrupt or its similar law
shall be filed in any court and such petition or answer shall not be discharged
within sixty (60) days after the filing thereof; or

              (v)   A receiver or trustee shall be appointed for all or
substantially all of the assets of Tenant or any Guarantor or of the Premises or
of any of Tenant's property located thereon; or

              (vi)  The leasehold estate hereunder shall be taken or attempt to
be taken by execution or other process of law in any action against Tenant; or

              (vii) Tenant shall abandon or vacate any substantial portion of
the Premises for a period of time in excess of five (5) days without written
permission of Landlord, except in connection with a sublease or assignment of
this Lease approved by Landlord.

          (b) In an event of default shall have occurred, Landlord shall have,
in addition to such other rights or remedies as are contained within this Lease
or at law or in equity, the right at its election, then or any time thereafter
while such event of default shall continue, to pursue any one or more of the
following remedies:

              (i)   Terminate this Lease by giving notice thereof to Tenant, in
which event Tenant shall immediately surrender the Premises to Landlord and if
Tenant fails to do so, Landlord may without prejudice to any other remedy which
it may have for possession or

 
arrearages in rent, enter upon and take possession of the Premises and expel or
remove Tenant and any other person who may be occupying the Premises, or any
part thereof, and by force, if reasonably necessary, without being liable for
prosecution or any claim of damages therefor and Tenant hereby agrees to pay to
Landlord on demand the amount of all loss or damage which Landlord may suffer by
reason of such termination, whether through inability to relet the Premises on
satisfactory terms or otherwise including loss of rental for the remainder of
the Lease Term and interest thereon at the Past Due Rate from the date of the
default.

              (ii)  Enter upon and take possession of the Premises and expel or
remove Tenant or any other person who may be occupying the Premises, or any part
thereof, by force, if reasonably necessary, without having any civil or criminal
liability therefor and without terminating this Lease.  Landlord may (but shall
be under no obligation to) relet the Premises or any part thereof for the
account of Tenant, in the name of Tenant or Landlord or otherwise, without
notice to Tenant, for such term or terms (which may be greater or less than the
period which would otherwise have constituted the balance of the term of this
Lease) and on such conditions (which may include concessions or free rent) and
for such uses as Landlord in its absolute discretion may determine and Landlord
may collect and receive any rents payable by reason of such reletting: and
Tenant covenants and agrees to pay Landlord on demand all reasonable expenses
necessary to relet the Premises which shall include the cost of renovating,
repairing, and altering the Premises for a new tenant or tenants, advertisements
and brokerage fees, and Tenant further covenants and agrees to pay Landlord on
demand any deficiency that may arise by reason of such reletting together with
interest on all sums due thereon as the Past Due Rate from the date of the
default.  Landlord shall not be responsible or liable for any failure to relet
the Premises or any part thereof or for any failure to collect any rent due upon
any such reletting.  No such re-entry or taking of possession of the Premises by
Landlord shall be construed as an election on Landlord's part to terminate this
Lease unless a written notice of such termination is given to Tenant pursuant to
subparagraph 23(b)(i) above.

              (iii) Make such payments and/or take such action (including,
without limitation, entering upon the Premises, by force if reasonably
necessary, without having any civil or criminal liability therefor) and do
whatever Tenant is obligated to do under the terms of this Lease and Tenant
covenants and agrees to reimburse Landlord on demand for any expenses which
Landlord may incur in thus affecting compliance with Tenant's obligations under
the Lease together with interest thereon at the Past Due Rate from the date paid
by Landlord, and Tenant further agrees that Landlord shall not be liable for any
damages resulting to Tenant from such action, unless caused by the negligence or
willful misconduct of Landlord.

              (iv)  Collect, from time to time, by suit or otherwise, each
installment of rent or other sum as it becomes due hereunder, or to enforce,
from time to time, by suit or otherwise, any other term or provision hereof on
the part of Tenant required to be kept or performed.

              (v)   In order to regain possession of the Premises and to deny
Tenant access thereto, Landlord or its agent may, at the expense and liability
of the Tenant, alter or change any or all locks or other security devices
controlling access to the Premises without posting or giving notice of any kind
to Tenant (except as expressly set forth in this Lease), in which event Landlord
shall place a written notice on Tenant's front door stating the name and 

 
address or telephone number of the individual or company from which access to
the new key may be obtained. However, Landlord shall have no obligation to
provide Tenant a key or grant Tenant access to the Premises so long as Tenant is
in default under this Lease. Tenant shall not be entitled to recover possession
of the Premises, terminate this Lease or recovery any actual, incidental,
consequential, punitive, statutory or other damages or award of attorneys' fees,
by reason of Landlord's alteration or change of any lock or other security
device and the resulting exclusion from the Premises of the Tenant or Tenant's
agents, servants, employees, customers, licensees, invitees or any other persons
from the Premises. Landlord may, without notice, remove and either dispose of or
store, at Tenant's expense, any property belonging to Tenant that remains in the
Premises after Landlord has regained possession thereof.

              (vi)  Terminate this Lease by giving Tenant notice hereof, in
which event Tenant shall pay to Landlord the sum of (i) all rent accrued
hereunder through the date of termination, and (iii) an amount equal to (A) the
total rent that Tenant would have been required to pay for the remainder of the
Lease Term discounted to present value at a rate of seven percent (7%) per
annum, minus (B) the then present fair rental value of the Premises for such
period, similarly discounted at a rate of seven percent (7%) per annum, after
deducting all anticipated costs of reletting and Landlord's expenses for keeping
the Premises in good order.

          (c) No repossession or re-entering on the Premises or any part thereof
and no reletting of the Premises or any part thereof shall terminate this Lease,
unless a notice of such intention be given to Tenant.

          (d) No right or remedy herein conferred upon or reserved to Landlord
is intended to be exclusive of any other right or remedy, and each and every
right and remedy shall be cumulative and in addition to any other right or
remedy given hereunder or now or hereafter existing at law or in equity or by
statute.  In addition to other remedies provided in this Lease, Landlord shall
be entitled, to the extent permitted by applicable law, to injunctive relief in
case of the violation, or attempted or threatened violation, of any of the
covenants, agreements, conditions, or provisions of this Lease, or to a decree
compelling performance of any of the other covenants, agreements, conditions, or
provisions of this Lease, or to any other remedy allowed to Landlord at law or
in equity.

     24.  NO IMPLIED WAIVER.  The failure of Landlord to insist at any time upon
the strict performance of any covenant or agreement or to exercise any option,
right, power, or remedy contained in this Lease shall not be construed as a
waiver or a relinquishment thereof for the future.  The waiver of or redress for
any violation of any term, covenant, agreement, or condition contained in this
Lease or contained in the Rules and Regulations attached hereto as Exhibit "B"
shall not prevent a subsequent act, which would have originally constituted a
violation from having all the force and effect of an original violation.  No
express waiver shall affect any condition other than the one specified in such
waiver and that one only for the time and in the manner specifically stated.  A
receipt by Landlord of any rent with or without knowledge of the breach of any
covenant or agreement contained in this Lease shall not be deemed a waiver of
such breach, and no waiver by Landlord of any provision of this Lease shall be
deemed to have been made unless expressed in writing and signed by Landlord.
Receipt by Landlord of Tenant's keys to the Premises shall not constitute an
acceptance or surrender of the Premises.

 
     25.  WAIVER BY TENANT.  Tenant hereby waives and surrenders for itself and
all claiming by, through, and under it, including creditors of all kinds,

          (a) any right and privilege which it or any of them may have under any
present or future constitution, statute or rule of law to redeem the Premises or
to have a continuance of this Lease for the term thereby demised after
termination of Tenant's right of occupancy by order or judgment of any court or
by any legal process or writ, or under the terms of this Lease, or after the
termination of the terms of this Lease as herein provided; and

          (b) the benefits of any present or future constitution, statute, or
rule of law which exempts property from liability for debt or for distress for
rent; and

          (c) the provision of law relating to notice and/or delay in levy of
execution in case of eviction of a tenant for nonpayment of rent.

     26.  ATTORNEYS' FEES AND LEGAL EXPENSES.  In the event either party
defaults in the performance of any of the terms, covenants, agreements or
conditions contained in this Lease to be performed by such party, and the
aggrieved party places the enforcement of this Lease in the hands of an
attorney, or files suit upon the same, the prevailing party shall recover all of
its reasonable attorneys' fees and court costs from the non-prevailing party.

     27.  LANDLORD'S LIEN.  In consideration of the mutual benefits arising
under this Lease, Tenant hereby grants to Landlord a lien and security interest
on all property of Tenant now or thereafter placed in or upon the Premises, and
such property shall be and remain subject to such lien and security interest of
Landlord for payment of all rent and other sums agreed to be paid by Tenant
herein.  Said lien and security interest shall be in addition to all rent and
other sums agreed to be paid by Tenant herein.  Said lien and security interest
shall be in addition to and cumulative of the Landlord's liens provided by law.
Tenant shall not remove any of said property from the Premises in the event
Tenant is in default under this Lease.  Upon the occurrence and event of default
by Tenant under this Lease, Landlord may, in addition to any other remedies
provided herein, enter upon the Premises and take possession of any and all
furniture, fixtures, equipment, supplies, and other property of Tenant situated
in, on, upon, or about the Premises, without liability for trespass or
conversion, and sell the same at public or private sale, with or without having
such property at the sale, after giving Tenant reasonable notice of the time and
place of any public sale or of the time after which any private sale is to be
made; and at any such public sale, Landlord or its assigns may purchase the same
or any portion thereof unless prohibited by law.  The proceeds of any such
disposition, less any and all expenses connected with the taking of possession,
holding and selling of the property (including reasonable attorneys' fees and
other expenses incurred by Landlord), shall be applied as a credit against the
indebtedness secured by the security interest granted in this Paragraph 27.  Any
surplus shall be paid to Tenant or as otherwise required by law; and Tenant
shall promptly pay any deficiencies forthwith.  This Lease shall constitute a
security agreement under the Taxes Uniform Commercial Code so that Landlord
shall have and may enforce a security interest on all property of Tenant now or
hereafter placed in or upon the Premises by Tenant.  Simultaneously with the
execution of this Lease, Tenant has executed as debtor the financing statements
attached hereto as Exhibit "E-1" or "E-2" and incorporated by reference herein
and agrees to execute such additional financing statement or statements as
Landlord may hereafter request in order that such 

 
security interest or interests may be protected pursuant to said Code. Landlord
may at its election at any time file a copy of this Lease as a financing
statement. Landlord, as secured party, shall be entitled to all of the rights
and remedies afforded a security party under the Texas Uniform Commercial Code,
which rights and remedies shall be in addition to and cumulative of the
Landlord's liens and rights provided by law or by the other terms and provisions
of this Lease. Upon request by Landlord, Tenant shall promptly provide the name
and address of any entity that has or claims to have an interest in any property
located on the Premises and a description of such property. Failure to provide
such list following Landlord's request shall result in a presumption that all
property located in the Premises is owned by or otherwise belongs to Tenant free
from all claims, liens, or security interests of any third party or parties.
Without intending to exclude any other manner of giving Tenant any required
notice, the requirement for reasonable notice shall be met if such notice is
given in the manner prescribed in this Lease at least ten (10) days before the
date of the sale. Landlord shall have all of the rights and remedies of a
secured party under applicable law. Upon written request by Tenant, Landlord
shall execute an agreement subordinating the foregoing lien of Landlord, in
substantially the form of Exhibit "1" attached hereto and made a part hereof.

     28.  SUBORDINATION.

          (a) Tenant acknowledges that this Lease and all rights of Tenant
hereunder are and shall remain subject and subordinate to that certain Deed of
Trust, Security Agreement, Fixtures Financing Statement and Assignment of Rents
and Leases dated December 13, 1991, executed by Landlord for the benefit of
Lender covering Landlord's interest in the Building and the Land, and recorded
in Volume 11584, Page 0737, of the Real Property Records of Travis County,
Texas, and any and all advances made on the security thereof and to any and all
increases, renewals, modifications, consolidations, replacements and extensions
and Tenant has, as of the date hereof, executed and delivered to Landlord that
certain Subordination, Non-Disturbance Agreement attached hereto as Exhibit "F"
and incorporated by reference herein (the "Non-Disturbance Agreement").
Notwithstanding the foregoing, Tenant acknowledges that Lender shall be under no
obligation to execute the Non-Disturbance Agreement in the event the Net
Rentable Area of the Premises is less than 2,500 square feet.

          (b) This Lease and all rights of Tenant hereunder shall be subject and
subordinate to any deeds of trust, mortgages or other instruments of security
which may hereafter cover the Building and the Land or any interest of Landlord
therein, and of any and all advances made on the security thereof, and to any
and all increases, renewals, modifications, consolidations, replacements and
extensions of any of such deeds of trust, mortgages or instruments of security,
subject to the approval and execution by Tenant and the holder or holders of
such deeds of trust, mortgages, or other instruments of security, which approval
and execution shall not be unreasonably withheld or delayed, of a subordination,
non-disturbance, and attornment agreement by the terms of which such holder or
holders recognize this Lease and covenant to give Tenant, so long as Tenant
attorns to any purchaser or purchasers of the Building and the Land or any
interest of Landlord therein through foreclosure or other disposition thereof
and Tenant is not in default under this Lease, the right of quiet enjoyment of
the Premises.  Tenant shall upon demand and at any time or times execute,
acknowledge, and deliver to Landlord such other and further instruments and
certificates that, in the judgment of Landlord, may be necessary or proper to
confirm or evidence such subordination.

 
     29.  QUIET ENJOYMENT.  The Tenant, upon paying the Base Rent, any
additional rent, and any other sums required to be paid by the terms of this
Lease, and upon performing and observing the covenants and stipulations set
forth herein, shall peaceably hold and enjoy the Premises during the said term
subject to the terms and conditions hereof and to any liens, ordinances,
easements, restrictions or covenants to which this Lease is subject.

     30.  NOTICE TO LANDLORD.  In the event of any act or omission by Landlord
which would give Tenant the right to damages from Landlord or the right to
terminate this Lease by reason of a constructive or actual eviction from all or
part of the written notice of such act or omission to Landlord and Landlord's
mortgagees, if any, and Landlord or Landlord's mortgagees shall fail to correct
the breach or default within thirty (30) days after the notice, or such longer
period of time as may be reasonably necessary provided Landlord or Landlord's
mortgagee has commenced to correct the breach or default within such thirty (30)
day period and diligently pursues such to completion.

     31.  HOLDING OVER BY TENANT.  Should Tenant or any of its successors in
interest continue to hold the Premises after the termination of this Lease,
whether such termination occurs by lapse of time or otherwise, such holding over
shall, unless otherwise agreed by Landlord in writing, constitute and be
construed as a tenancy at will, at a daily rental equal to one-thirtieth (1/30)
of an amount equal to the greater of double the amount of the monthly rental
payable during the last month prior to the termination of this Lease or one
hundred fifty percent (150%) of the market rate for which similar space in the
Building is then being leased by Landlord, and upon and subject to all of the
other terms, provisions, covenants, and agreements on the part of Tenant
hereunder except any right to renew this Lease.  No payments of money by Tenant
to Landlord after the termination thereof shall be valid unless and until the
same shall be reduced to writing and signed by both Landlord and Tenant.
Nothing in this Paragraph 31 shall be construed as giving Tenant the right to
hold over beyond the date of the expiration of this Lease nor preclude Landlord
from having the right to dispossess or otherwise terminate Tenant's right of
possession.  Any tenancy at will is terminable upon notice from Landlord.

     32.  RULES AND REGULATIONS.  Tenant and Tenant's agents, employees, and
invitees will comply with all requirements of the Rules and Regulations (as
changed from time to time as hereinafter provided) which are attached hereto as
Exhibit "B."  Landlord shall at all times have the right to change such Rules
and Regulations or to promulgate other Rules and Regulations in such reasonable
manner as may be deemed advisable for the safety, care, or cleanliness of the
Building and related facilities or premises, and for preservation of good order
therein; provided, however, that such changes shall not become effective and a
part of this Lease until a copy thereof shall have been delivered to Tenant and
provided further that Landlord shall use reasonable efforts to enforce such
rules in a fair and equitable manner among all tenants in the Building and shall
not make any rule that would deprive Tenant (except in times of emergency) of
access to and use of the Premises during evenings, weekends and holidays.
Tenant shall further be responsible for the compliance with such Rules and
Regulations by the employees, servants, agents, visitors, and invitees of
Tenant.  Landlord shall not be responsible to Tenant for failure of any person
to comply with such Rules and Regulations.

     33.  ESTOPPEL CERTIFICATE AND TENANT'S FINANCIAL STATEMENTS.  Tenant will,
at any time and from time to time, upon not less than twenty (20) days' prior
request by Landlord or 

 
any successor of Landlord or by the holder of any deed of trust or mortgage
covering the Land and Building or any interest of Landlord therein, execute,
acknowledge, and deliver to Landlord an estoppel certificate prepared by
Landlord (or by any such successor of Landlord or by any such holder)
certifying, if true and accurate at the time (and if not, stating why) that this
Lease is the entire agreement between the parties; that this Lease is in full
force and effect and specifying any modifications; the dates to which the rent
has been paid and that no rent under this Lease has been paid more than thirty
(30) days in advance of its due date; that the Tenant has unconditionally
accepted the Premises; that any improvements required by the terms of this Lease
to be made by Landlord have been completed to the satisfaction of Tenant; that
the address for notices to be sent to Tenant is as set forth in this Lease; that
Tenant, as of the date of such certificate, has no charge, lien or claim of
offset, deduction or counterclaim under this Lease or otherwise against rents or
other charges due or to become due hereunder; that Landlord, any such successor
or holder, and any assignee of any such entity may rely upon the estoppel
certificate being given by Tenant; and either stating that to the knowledge of
the signer of such certificate no default of Landlord exists hereunder or
specifying each such default of which the signer may have knowledge; it being
intended that any such certificate by Tenant may be relied upon by any
prospective purchaser or mortgagee of the Building. In addition to the matters
described above, the above-described certificate shall include and Tenant shall
certify, if true and accurate at the time (and if not, stating why) as to
matters regarding the Lease as reasonably requested by Landlord. The certificate
shall also contain an acknowledgment by Tenant of receipt of notice of the
assignment of this Lease to such holder and the agreement by Tenant with such
holder that from and after the date of such certificate, Tenant will not pay any
rent under this Lease more than thirty (30) days in advance of its due date,
will not surrender or consent to the modification of any of the terms of this
Lease nor to the termination of this Lease by Landlord, and will not seek to
terminate this Lease by reason of any act or omission of Landlord until Tenant
shall have first given written notice of such act or omission to the holder of
such deed of trust or mortgage (at such holder's last address furnished to
Tenant) and until a reasonable period of time shall have elapsed following the
giving of such notice, during which period such holder shall have the right, but
shall not be obligated, to remedy such act or omission; provided, however, that
(i) the agreement of Tenant described in this sentence will be of no effect
under such certificate unless Tenant is furnished by such holder with a copy of
any assignment to such holder of Landlord's Interest in this Lease within ninety
(90) days after the date of such certificate, and (ii) the agreement of Tenant
with such holder that is embodied in such certificate shall terminate upon the
subsequent termination of any such assignment. If requested by Landlord, Tenant
shall also furnish to Landlord, within thirty (30) days of such request (which
Landlord shall not make more often than once in any twelve (12) month period), a
statement of the financial condition of Tenant in a form reasonably satisfactory
to Landlord. Landlord will at any time and from time to time, upon not less than
thirty (30) days' prior request by Tenant, any successor in interest of Tenant
or by any of Tenant's lenders, execute, acknowledge and deliver to Tenant an
estoppel certificate prepared by Tenant (or by any such successor or lender of
Tenant) in form and substance equivalent of the estoppel certificate Tenant has
agreed to provide Landlord pursuant to this Paragraph 33.

     34.  LIMITATION OF LIABILITY.  The liability of Landlord to Tenant for any
default by Landlord under the terms of this Lease shall be limited to the then
interest of Landlord in the Building and Land and Landlord, its officers,
directors, employees, agents and partners shall not be personally liable for any
deficiency.  This clause shall not be deemed to limit or deny any 

 
remedies which Tenant may have in the event of default by Landlord hereunder
which do not involve the personal liability of Landlord. Notwithstanding
anything contained in this Lease to the contrary, in the event Landlord sells,
assigns, transfers, or conveys its interest in the Land and the Building.
Landlord shall have no liability for any acts or omissions that occur after the
date of said sale, assignment, transfer, or conveyance. The provisions of this
Paragraph shall survive the expiration of earlier termination of this Lease.

     35.  NOTICES.  Each provision of this Lease, or of any applicable
governmental laws, ordinances, regulations, and other requirements with
reference to the sending, mailing, or delivery of any notice or with reference
to the making of any payment by Tenant to Landlord, shall be deemed to be
complied with when and if the following steps are taken:

          (a) All rent and other payments required to be made by Tenant to
Landlord hereunder shall be payable to Landlord in Travis County, Texas, at the
address hereinbelow set forth, or at such other address as Landlord may specify
from time to time by written notice delivered in accordance herewith:

                    San Jacinto Office Tower Limited Partnership
                    300 San Jacinto Center
                    98 San Jacinto Blvd.
                    Austin, Texas 78701
                    Attn:  Property Manager

          (b) Any notice or document delivered by Tenant to Landlord hereunder
shall be delivered to Landlord at the address hereinbelow set forth, or at such
other address as Landlord may specify from time to time by written notice
delivered in accordance herewith:

   With a copy to:  Equity Assets Management, Inc.
                    2 North Riverside Plaza, Suite 1601
                    Chicago, Illinois 60606
                    Attn:  Vice President, Ownership Representation

          (c) Any notice or document delivered by Landlord to Tenant hereunder
shall be delivered to Tenant at the address hereinbelow set forth, or at such
other address as Tenant may specify from time to time by written notice
delivered in accordance herewith:

                    230 San Jacinto Center
                    98 San Jacinto Blvd.
                    Austin, Texas 78701
                    Attn:  Richard J. Hawkins

          (d) Any notice or document required to be delivered hereunder shall be
deemed to be delivered, whether actually received or not, when deposited in the
United States mail, postage paid, certified mail, return receipt requested,
addressed to the respective party at the respective addresses set out above, or
at such other address as they have theretofore specified by written notice.

 
     36.  USE TAX.  Notwithstanding any other provision herein, Tenant shall pay
as and when they become due and before the same become delinquent any and all
licenses, charges, and other fees of every kind and nature arising out of or in
connection with the Tenant's use or occupancy of the Premises, including but not
limited to license fees, business license tax, the amount of any privilege,
sales, excise, or other tax (other than income or franchise tax) imposed upon
rentals herein provided to be paid by Tenant or upon the Landlord in an amount
measured by such rentals received by Landlord.

     37.  EXECUTION AND APPROVAL OF LEASE.  Employees or agents of Landlord's
broker, if any, or Landlord's building manager, if any, have no authority to
make or agree to make a lease or any other agreement or undertaking in
connection herewith.  The submission of this document for examination and
negotiation does not constitute an offer to lease, or a reservation of, or
option for, the Premises and this document for examination and negotiation does
not constitute an offer to lease, or a reservation of, or option for, the
Premises and this document becomes effective and binding only upon the execution
and delivery hereof by Landlord or Landlord's authorized agent and Tenant.  All
negotiations, considerations, representations and understandings between
Landlord and Tenant are incorporated herein and may be modified or altered only
by agreement in writing between Landlord and Tenant, and no act or omission of
any employee or grant of Landlord, Landlord's broker, if any, or Landlord's
building manager, if any, shall alter, change or modify any of the provisions
hereof.

     38.  SEVERABILITY.  Each and every covenant and agreement contained in this
Lease is, and shall be construed to be, a separate and independent covenant and
agreement.  If any term or provision of this Lease or the application thereof to
any person or circumstances shall to any extent be invalid and unenforceable,
the remainder of this Lease, or the application of such term or provision to
persons or circumstances other than those as to which it is invalid or
unenforceable, shall not be affected thereby and in lieu of such invalid or
unenforceable clause, there shall be added as a part of the Lease a clause as
similar in terms to such invalid or unenforceable clause as may be possible and
be legal, valid and enforceable.

     39.  NO MERGER.  There shall be no merger of this Lease or of the leasehold
estate hereby created with the fee estate in the Premises or any part thereof by
reason of the fact that the same person may acquire or hold, directly or
indirectly, this Lease or the leasehold estate hereby created or any interest in
this Lease or in such leasehold estate as well as the fee estate in the Premises
or any interest in such fee estate.

     40.  FORCE MAJEURE.  Whenever a period of time is herein prescribed for
action (other than the payment of money) to be taken by a party to this Lease,
that party shall not be liable or responsible for, and there shall be excluded
from the computation for any such period of time, any delays due to strikes,
acts of God, shortages of labor or materials, war, governmental laws,
regulations, restrictions, or any other cause of any kind whatsoever which is
beyond the control of that party ("Force Majeure").

     41.  GENDER.  Words of any gender used in this Lease shall be held and
construed to include any other gender and words in the singular number shall be
held to include the plural, unless the context otherwise requires.

 
     42.  JOINT AND SEVERAL LIABILITY.  If there is more than one Tenant, the
obligations hereunder imposed upon Tenant shall be joint and several.  If there
is a guarantor of Tenant's obligations hereunder, the obligations of Tenant
shall be joint and several obligations of Tenant and such guarantor, and
Landlord need not first proceed against Tenant hereunder before proceeding
against such guarantor, nor shall any such guarantor be released from its
guarantee for any reason whatsoever, including, but not limited to, any
amendment of this Lease, any forbearance by Landlord or waiver of any of
Landlord's rights, the failure to give Tenant or such guarantor any notices, or
the release of any party liable for the payment of Tenant's obligations
hereunder.

     43.  ENTIRE AGREEMENT AND AMENDMENT.  This Lease contains the entire
agreement between the parties hereto with respect to the subject matter hereof
and supersedes any and all prior and contemporaneous agreements, understandings,
promises, and representations made by either party to the other concerning the
subject matter hereof and the terms applicable hereto.  Landlord's agents have
made no representations or promises with respect to the Premises of the Building
except as herein expressly set forth and no rights, easements, or licenses are
acquired by Tenant by implication or otherwise except as expressly set forth in
the provisions of this Lease.  This Lease shall not be altered, waived, amended
or extended, except as expressly set forth in the provisions of this Lease.
This Lease shall not be altered, waived, amended or extended, except by a
written agreement signed by the parties hereto, unless otherwise expressly
provided herein.  Neither this Lease nor a memorandum of this Lease shall be
recorded in the public records of the county in which the Building is located
without the prior written consent of Landlord.

     44.  PARAGRAPH HEADINGS.  The paragraph headings contained in this Lease
are for convenience only and shall in no way enlarge or limit the scope or
meaning of the various and several paragraphs hereof.

     45.  BINDING EFFECT.  All of the covenants, agreements, terms, and
conditions to be observed and performed by the parties hereto shall be
applicable to, binding upon and inure to the benefit of their respective heirs,
personal representatives, successors, and, their respective assigns, subject to
the provisions of Paragraphs 11, 34 and 46 hereof.

     46.  TRANSFER OF LANDLORD'S RIGHTS.  Subject to any express provisions of
this Lease to the contrary, in the event Landlord transfers its interest in the
Building, Landlord shall thereby be released from any further obligations
hereunder, and Tenant agrees to look solely to the successor in interest of
Landlord for the performance of such obligations.

     47.  BROKERAGE.  Tenant and Landlord represent and warrant to each other
that such party has not had any dealing with any realtor, broker or agent in
connection with this Lease or the negotiation thereof, except for First Office
Management and Asset Investment Corp. to which Landlord shall be liable for the
payment of all fees, commissions, and other compensation and charges pursuant to
separate written agreements between Landlord and each such broker, and Landlord
and Tenant each agree to indemnify and hold the other harmless from and against
any and all costs, expenses or liability, including, but not limited to,
reasonable attorney's fees, resulting from any breach of this representation or
warranty.

 
     48.  NO THIRD PARTY BENEFICIARY.  This Lease is for the sole benefit of
Landlord, its successors and assigns, and Tenant, its permitted successors and
assigns, and is not for the benefit of any third party.

     49.  SUBSTITUTION OF PREMISES.  At any time after the execution of this
Lease with not less than sixty (60) days' prior written notice, Landlord may
substitute for the Premises other premises in the Building (the "New Premises"),
in which event the New Premises shall be deemed to be the Premises for all
purposes hereunder provided:  (a) the New Premises shall contain at least the
same Net Rentable Area as the Premises, (b) the Base Rent and Tenant''
Proportionate Share shall be proportionately adjusted based upon the size of the
New Premises, (c) the New Premises shall have been finished out in no less than
the same overall manner as the Premises, (d) the New Premises shall be of
similar structural integrity, quality and convenience, (e) Landlord shall pay
Tenant's reasonable moving expenses and (f) the terms of this Lease, other than
those dealing specifically with the physical features or location of the
Premises, shall apply to the New Premises.  If Tenant fails to vacate the
Premises after demand therefor by Landlord, Tenant shall thereupon be in default
under the Lease.

     50.  HAZARDOUS WASTE.  The term "Hazardous Substances," as used in this
Lease, shall mean pollutants, contaminants, toxic or hazardous wastes,
radioactive materials or any other substances, the use and/or the removal of
which is required or the use of which is restricted, prohibited or penalized by
any "Environmental Law," which term shall mean any federal, state or local
statute, ordinance, regulation or other law of a government or quasi-
governmental authority relating to pollution or protection of the environment or
the regulation of the storage or handling of Hazardous Substances.  Landlord
hereby represents to Tenant that to Landlord's current actual knowledge, there
are currently no Hazardous Substances stored or used in the Building or the
Premises, no underground storage tanks located on or under the Land and no
asbestos used in the construction of the Building or any leasehold improvements
in the Building.  Tenant hereby agrees that:  (i) Tenant, its agents, employees
and contractors will not conduct any activity on the Premises that will produce
any Hazardous Substance; (ii) Tenant, its agents, employees and contractors will
not use the Premises in any manner for the storage of any Hazardous Substances;
(iii) Tenant will not permit any Hazardous Substances to be brought onto the
Premises and if so brought or found located thereon, the same shall be
immediately removed, with proper disposal, and all required clean-up procedures
shall be diligently undertaken by Tenant at its sole cost pursuant to all
Environmental Laws.  If at any time during or after the term of this Lease, the
Premises is found to be contaminated with Hazardous Substances and such
contamination is the result of action by Tenant, its agents, employees or
contractors, Tenant shall diligently institute proper and thorough clean-up
procedures, at Tenant's sole cost.  If at any time during the Lease Term, the
Premises is found to be contaminated with Hazardous Substances, and such
contamination is the result of action by Landlord, Landlord shall diligently
institute proper and thorough clean-up procedures, at Landlord's sole cost.
Landlord agrees to indemnify and hold Tenant harmless from all fines,
reimbursement, restitution, response costs, cleanup costs, claims, demands,
actions, liabilities, costs, expenses, damages, penalties and obligations of any
nature arising from or as a result of any contamination of the Premises with
Hazardous Substances as a result of Landlord's actions or otherwise arising from
the use of the Land or Building by Landlord.  Tenant agrees to indemnify and
hold Landlord harmless from all fines, reimbursement, restitution, response
costs, cleanup costs, claims, demands, actions, liabilities, costs, expenses,
damages, penalties and obligations of any nature arising from or as a result of

 
any contamination of the Premises with Hazardous Substances (other than as a
result of Landlord's actions), or otherwise arising from the use of the
Premises, Land or Building by Tenant.  The foregoing indemnification and the
responsibilities of Tenant and Landlord shall survive the termination or
expiration of this Lease.

     51.  APPLICABLE LAW.  This Lease shall be governed in all respects by the
laws of the State of Texas.  It is the intent of Landlord and Tenant to conform
strictly to all applicable state and federal usury laws.  All agreements between
Landlord and Tenant, whether now existing or hereafter arising and whether
written or oral, are hereby expressly limited so that in no contingency or event
whatsoever shall the amount contracted for, charged or received by Landlord for
the use, forbearance or detention of money hereunder or otherwise exceed the
maximum amount which Landlord is legally entitled to contract for, charge or
collect under applicable state or federal law.  If, from any circumstance
whatsoever, fulfillment of any provision hereof at the time performance of such
provision shall be due shall involve transcending the limit of validity
prescribed by law, then the obligation to be fulfilled shall be automatically
reduced to the limit of such validity, and if from any such circumstance,
Landlord shall ever receive as interest or otherwise an amount in excess of the
maximum that can be legally collected, then such amount which would be excessive
interest shall be applied to the reduction of the rent; and if such amount which
would be excessive interest exceeds the rent, then such additional amount shall
be refunded to Tenant.

     52.  AUTHORITY.  In the event Tenant is a corporation (including any form
of professional association), partnership (general or limited) or other form of
organization other than an individual, then each individual executing or
attesting this Lease on behalf of Tenant hereby covenants, warrants and
represents (i) that such individual is duly authorized to execute or attest and
deliver this Lease on behalf of Tenant in accordance with the organizational
documents of Tenant; (ii) that this Lease is binding upon Tenant; (iii) that
Tenant is duly organized and legally existing in the state of its organization,
and is qualified to do business in the state in which the Premises is located;
(iv) that upon request, Tenant will provide Landlord with true and correct
copies of all organizational documents of Tenant and any amendments thereto; and
(v) that the execution and delivery of this Lease by Tenant will not result in
any breach of, or constitute a default under, any mortgage, deed of trust,
lease, loan, credit agreement, partnership agreement or other contract or
instrument to which Tenant is a party or by which Tenant may be bound.  If
Tenant is a corporation, Tenant will, prior to the Commencement Date, deliver to
Landlord a copy of a resolution of Tenant's board of directors authorizing or
ratifying the execution and delivery of this Lease, which resolution will be
duly certified to Landlord's satisfaction by the secretary or assistant
secretary of Tenant.  Tenant acknowledges that the financial capability of
Tenant to perform its obligations hereunder is material to Landlord and that
Landlord would not enter into this Lease but for its belief, based on its review
of Tenant's financial statements, that Tenant is capable of performing such
financial obligations.  Tenant hereby represents, warrants and certifies to
Landlord that its financial statements previously furnished to Landlord were at
the time given true and correct in all material respects and that there have
been no material subsequent changes thereto as of the date of this Lease.

     53.  WARRANTY OF GOOD TITLE.  Landlord warrants and represents to Tenant
that Landlord owns good and sufficient right, title and interest in and to the
Land and all 

 
improvements thereto, including, without limitation, the Building, such that
Landlord may enter into this Lease and be bound by its terms. In entering into
this Lease with Landlord, Tenant is specifically relying on this representation
of good title by Landlord.

     54.  CANCELLATION OPTION.

          (a) Provided Tenant is not in default hereunder at both the time of
exercise of such option and the Cancellation Date (as hereinafter defined), and
subject to the requirements of this Paragraph 54, Tenant shall have the option
to terminate this Lease (the "Cancellation Option") at any time after the last
day of the twenty-fourth (24th) calendar month of the Lease Term, such
termination to be effective on the date (the "Cancellation Date") which is six
(6) months after the date Landlord receives written notice from Tenant of the
exercise of such right.  In order to exercise the Cancellation Option, Tenant
must (i) provide six (6) months' prior written notice to Landlord of Tenant's
exercise of the Cancellation Option, (ii) pay to Landlord, at the same time that
Tenant delivers to Landlord the foregoing notice of cancellation, a cancellation
fee in the amount of $8,464.14 (if Tenant notifies Landlord of its exercise of
the Cancellation Option prior to the last day of the thirty-sixth (36th)
calendar month of the Lease Term) and (iii) execute a written lease agreement
with Landlord on or before the Cancellation Date (the "New Lease") in accordance
with subsection (b) below.  The payment of the cancellation fee described in
(ii) above shall not reduce any of Tenant's obligations under this Lease
accruing up to and including the Cancellation Date.  There shall be no such
cancellation fee due and payable in the event Tenant notifies Landlord of its
exercise of the Cancellation Option after the last day of the thirty-sixth
(36th) calendar month of the Lease Term.  In the event that Tenant fails to
comply with all the terms and conditions set forth in items (i), (ii) and (iii)
above, the Cancellation Option shall be void and of no further force and effect.

          (b) The New Lease shall be for a term of no less than sixty (60)
months commencing the day after the Cancellation Date and shall cover space in
the Building containing not less than 6,000 square feet of Net Rentable Area in
a location designated by Landlord, subject to the availability of such space in
the Building, "upon all of the same terms and conditions set forth in the Lease,
except as provided above and as set forth below:

              (i)   The Base Rent for the Lease Term of the New Lease shall be
the Fair Market Value Rental Rate for such new space as of the applicable
commencement date set forth above, as determined by Landlord in good faith. As
used in this Paragraph, the term "Fair Market Value Rental Rate" shall mean the
annual rental rate being charged as of the date such rental is to become
effective hereunder for tenants then initially occupying space of comparable
size and condition (to the space for which the Fair Market Value Rental Rate is
being determined) in the Building if, but only if, there is then an active
leasing market for initial occupancies of such comparable space in the Building.
If no active leasing market for initial occupancies in the Building then exists,
then the Fair Market Value Rate shall mean the annual rental rate then being
charged in the Market Area (as defined below) for tenants then initially
occupying space in comparable buildings in the Market Area, for space of
comparable size and condition to the space for which the Fair Market Value
Rental Rate is being determined. In either case, the Fair Market Value Rental
Rate shall take into consideration use, location and floor level within the
building, the location, quality and age of the building, the definition of
rentable area or net rentable area, as the case may be, with respect to which
such rental rates are

 
computed, leasehold improvements provided or to be provided, the term of the
lease under consideration, the extent of the services provided or to be
provided, applicable distinctions between "gross" leases and "net" leases, base
year or dollar amount for escalation purposes (both operating costs and ad
valorem/real estate taxes), any other adjustments (including by way of indices)
to base rental (taking into consideration rent concessions and abatement for
purposes of computing "effective" rental rates only and in no event shall there
be any rental abatement under this Lease other than as specifically provided in
this Lease), credit standing and financial stature of tenant, the time the
rental rate under consideration was agreed upon and became or is to become
effective, and any other relevant term or condition in making such evaluation.
As used herein, the "Market Area" means the downtown area of Austin, Texas,
bounded on the south by Town Lake, on the north by 12th Street, on the east by
Red River and on the west by Guadalupe.

              (ii)  Any space leased by Tenant under this Paragraph shall be
tendered by Landlord and accepted by Tenant in its then "AS IS" condition,
provided that Landlord shall provide to Tenant the renovation allowance (if any)
which was assumed in Landlord's determination of the Fair Market Value Rental
Rate. Unless then otherwise agreed in writing by Landlord and Tenant, such
allowance shall be furnished to Tenant pursuant to, and Tenant shall comply
with, the Renovation Work Letter attached hereto and made a part hereof as
Exhibit "G".

              (iii) Tenant's rights under this Paragraph 54 are personal with
respect to Tenant, and any assignment or subletting by Tenant shall
automatically terminate its rights under this Paragraph 54.

              (iv)  Landlord shall not be liable for the failure to give
possession of any space leased under this Paragraph to Tenant by reason of the
unauthorized holding over or retention of possession by any other tenant,
tenants, or occupants thereof, nor shall such failure impair the validity of
this Lease, nor extend the term thereof.

              (v)   The unamortized portion (as of the Cancellation Date) of all
up front costs paid by the Landlord in connection with this Lease (i.e.,
brokerage commissions plus the Leasehold Improvement Allowance), together with
interest thereon at the rate of 13% per annum, shall be amortized evenly over
the lease term of the New Lease and shall be added to the Base Rent under the
New Lease.

              (vi)  In the event that any such space is not available in the
Building and/or in the event that Tenant fails to execute a lease for such space
prior to the Cancellation Date, such exercise of the Cancellation Option shall
be null and void; provided, however, that the foregoing unavailability of space
shall not preclude Tenant from exercising the Cancellation Option later in the
Lease Term, subject to all of the terms and conditions hereof.

     55.  TEMPORARY STORAGE SPACE.  Landlord shall provide temporary storage
space to Tenant prior to the Commencement Date at no cost to Tenant, subject to
availability of such space in the Building.  Such storage space shall be in a
location to be determined by Landlord, in Landlord's sole discretion, which
shall contain no more than 500 square feet.  The term of such temporary lease
shall not exceed 60 days and such space shall be used by Tenant solely for the
purpose of temporarily storing Tenant's personal property, furniture and
equipment.

 
     56.  TEMPORARY PREMISES.  Tenant shall lease from Landlord upon all of the
terms and conditions of this Lease, as modified by this Paragraph, that certain
area within the Building containing approximately 2,352 square feet of Net
Rentable Area, known as Suite 1450 and as shown on Exhibit "A-1" attached hereto
and made a part hereof (the "Temporary Premises").  The Lease  Term for the
Temporary Premises shall commence on the day which is three (3) business days
after Landlord notifies Tenant that the Temporary Premises is available for
occupancy, and shall end on the day before the Commencement Date.  The Base Rent
for the Temporary Premises shall be $1,500.00 per month.  Tenant shall accept
the Temporary Premises in its "AS IS" condition and Landlord shall have no
obligation to provide any improvements to or perform any work in the Temporary
Premises.

     57.  AFFILIATED ENTITIES.  Tenant and Landlord acknowledge that Tenant is
engaged in the business of acquiring, developing and marketing technologies, and
that in connection with this business, it may from time to time form affiliated
entities which will undertake various development or marketing activities.
These affiliated entities shall be subject to the control of or under common
control with Tenant and may employ their own personnel.  Such personnel may
maintain offices within the Premises in connection with their work on behalf of
such affiliated entities.  Such occupancy of the Premises by such personnel
shall be subject to and in accordance with all of the terms and conditions of
this Lease and the foregoing shall not be deemed in any manner to release or
otherwise modify in any manner Tenant's obligations under this Lease.

     58.  RIDERS AND EXHIBITS.  The following number Exhibits and Riders are
attached hereto and incorporated herein by reference as if copied herein in
full.

          Exhibit "A":     Floor Plan of Premises
          Exhibit "A-1":   Floor Plan of Temporary Premises
          Exhibit "B":     Building Rules and Regulations
          Exhibit "C":     Acceptance of Premises Memorandum
          Exhibit "C-1":   Punch List
          Exhibit "D":     Work Letter
          Exhibit "E-1":   Secretary of State Financing Statement
          Exhibit "E-2":   Travis County Clerk's Financing Statement
          Exhibit "F":     Subordination, Non-Disturbance and Attornment 
                           Agreement
          Exhibit "G":     Renovation Work Letter
          Exhibit "H":     Lease Guaranty
          Exhibit "I":     Agreement Regarding Lender's Security Interest
          Rider No. 101    Definitions Regarding Calculation of Tenant's
                           Occupancy Costs and Calculation of Net Rentable Area
          Rider No. 102    Parking

 
     IN WITNESS WHEREOF, this Lease is hereby executed in multiple originals as
of the date first above set forth.

                                LANDLORD
 
                                SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, a
                                Texas limited partnership

                                By:  Equity Assets Management, Inc., its
                                authorized agent


                                By:   /s/ Richard J. Berk
                                    --------------------------------------------
                                Name:  Richard J. Berk
                                Title:  Vice President, Ownership Representation



                                TENANT

                                DRUG DEVELOPMENT INVESTMENT CORP., a Texas
                                corporation d/b/a id2, Inc.


                                By:   /s/ Richard J. Hawkins
                                    --------------------------------------------
                                Name:  Richard J. Hawkins
                                Title:  Chairman of the Board of Directors


                                ID2 1, L.P., A TEXAS LIMITED PARTNERSHIP

                                By:  Drug Development Investment Corp., a Texas
                                     corporation d/b/a id2, Inc., its sole
                                     general partner

                                       By:   /s/ Richard J. Hawkins
                                           -------------------------------------
                                       Name:  Richard J. Hawkins
                                       Title:  Chairman of the Board of Director

 
                                  EXHIBIT "H"
                                        
                               GUARANTY OF LEASE

     WHEREAS, Drug Development Investment Corp. d/b/a id2  I, L.P. (jointly,
"Tenant") have entered into that certain Lease Agreement (the "Lease") date
March 17, 1993 with San Jacinto Office Tower Limited Partnership ("Landlord");
and

     WHEREAS, Landlord was not willing to enter into the Lease without the
receipt of this Guaranty executed and acknowledge by the undersigned;

     NOW, THEREFORE, to induce Landlord to execute the Lease, as a material
consideration and inducement therefore (recognizing without the execution and
delivery of this Guaranty Landlord would not be willing to enter into the Lease
Amendment), and recognizing the benefit of the Lease to the undersigned, the
undersigned hereby agree as follows:

     The undersigned (herein called "Guarantors" whether one or more), hereby
unconditionally, jointly and severally guarantee observance by Tenant of all the
monetary obligations, duties, covenants, agreements and conditions provided in
the Lease, as same may hereafter be amended from time to time, to be observed by
Tenant during the term of the lease (including specifically and without limiting
the generality of the foregoing, payment by Tenant of all rental and other
amounts and damages of whatsoever kind or nature which may be or become due from
Tenant under the terms of or in connection with the Lease).  This guaranty is
unconditional and the liability of Guarantors shall be absolute, in the same
manner as if Guarantors, jointly and severally, were named in and had signed the
Lease as "Tenant" thereunder.  Guarantors agree that bankruptcy, insolvency,
lack of corporate capacity or any other disability or impediment against
enforcement of full liability of Tenant named in the Lease shall in no way
impair or affect Guarantors' liability and obligation hereunder, and, without
limitation of the foregoing.  Guarantors agree that in the event that Tenant
shall become insolvent or shall be adjudicated a bankrupt, or shall file a
petition for reorganization, arrangement or other relief under any present or
future provisions of the Bankruptcy Code, or if such a petition be filed by
creditors of Tenant, or if Tenant shall seek a judicial readjustment of the
rights of its creditors under any present or future federal or state law or if a
receiver of all or part of Tenant's property and assets is appointed by any
state or federal court, no such proceeding or action taken therein shall modify,
diminish or in any way affect the liability of Guarantors under this guaranty,
and the liability of Guarantors of the Tenant's obligations under the Lease
shall be of the same scope as if Guarantors had themselves, jointly and
severally, executed the Lease, and no "rejection" and/or "termination" of the
Lease in any of the proceedings referred to above shall be effective to limit,
release and/or terminate the continuing liability of Guarantors to Landlord
under this guaranty with respect to the Lease and such liability of Guarantors
shall be unaffected by any such "rejection" and/or "termination" in said
proceedings.  It shall not be necessary or required in order to maintain and
enforce Guarantors' liability hereunder that demand be made upon Tenant or that
action be commenced or prosecuted against Tenant or that any effort be made to
enforce the liability or responsibility of Tenant for performance of its
obligations or duties under or in connection with the Lease, and it shall not be

 
required that Tenant or any other party liable on such lease be joined in any
action brought against Guarantors for enforcement of Guarantors' liability and
responsibility under this guaranty or that judgement have theretofore been
obtained against Tenant or any other party liability therefor on or in
connection with any such claim.  Guarantors agree that no waiver by Landlord or
forbearance or delay by Landlord in asserting or enforcing any rights or
remedies of Landlord against or with respect to Tenant or any other party who
may be or becomes responsible for performance of any such Tenant's obligations
or duties shall in any way affect, impair or release Guarantors' liability
hereunder.  Likewise, Guarantors agree that no assignment or subletting of the
Lease or of all or any part of the leased premises by such Tenant shall in any
way impair, affect or release Guarantors' liability hereunder.  Guarantors
expressly waive and agree that no notice of default by Tenant or other notice or
demand need be given by Landlord to Guarantors as a condition of maintaining or
enforcing Guarantors' liability and obligations under this guaranty.  Guarantors
expressly agree that no notice of amendment or modification of the Lease need be
given by Landlord or Tenant to Guarantors as a condition of maintaining or
enforcing Guarantors' liability and obligations under this guaranty.  Guarantors
expressly agree that any amendment or modification of the Lease be made by
Landlord and Tenant, as provided in such lease, with or without the approval of
Guarantors, and that any such amendment will be deemed part of the Lease for
purposes of this guaranty.  Likewise, Guarantors agree that Landlord's release
or subordination or failure or delay to enforce or seek to realize upon any
security now or hereafter held or acquired by Landlord for performance of any of
the obligations or duties of Tenant under or in connection with the Lease shall
in no way impair, affect or release Guarantors' liability hereunder, and that
Landlord's action (at Landlord's election) in terminating such lease or in
taking or retaking possession of the leased premises as therein provided
following default by Tenant shall not release or impair Guarantors' liability
hereunder and that no notice of such termination or of such entry or re-entry by
Landlord need be given to Guarantors.  Without limitation of anything herein to
the contrary, Guarantors agree that any wavier by Lessor or forbearance or
failure or delay by Lessor in asserting or enforcing its rights against any of
the undersigned under this guaranty shall in no way affect, impair or release
the liability of any of the other Guarantors hereunder.

     NOTHWITHSTANDING ANYTHING HEREIN TO THE CONTRARY, THE MAXIMUM LIABILITY OF
GUARANTOR HEREUNDER, SHALL BE LIMITED TO $75,807.00, PLUS ALL COSTS, INCLUDING
WITHOUT LIMITATION REASONABLE ATTORNEYS' FEES, INCURRED IN ENFORCING THIS
GUARANTY (THE "GUARANTEED AMOUNT").  THE GUARANTEED AMOUNT SHALL BE REDUCED BY
$1,263.46 FOR EACH FULL MONTH OF THE LEASE TERM IN WHICH TENANT PERFORMS ALL OF
ITS MONETARY OBLIGATIONS UNDER THE LEASE.

     This guaranty shall be enforceable and shall be performed in Travis County,
Texas.

 
     WITNESS the execution hereof effective as of the date of execution and
delivery of the Lease.


Address:                            __________________________________________
230 San Jacinto Center              Richard J. Hawkins
98 San Jacinto Blvd.
Austin, TX  78701

 
                                  EXHIBIT "F"
                                        
                      SUBORDINATION, NON-DISTURBANCE AND

                             ATTORNMENT AGREEMENT

                                        

THE STATE OF TEXAS      (SECTION)

                        (SECTION)

COUNTY OF TRAVIS        (SECTION)

     THIS SUBORDINATION, NON-DISTURBANCE AND ATTORNMENT AGREEMENT dated as of
________________________, 19____, is executed by and among SAN JACINTO OFFICE
TOWER LIMITED PARTNERSHIP, a Texas limited partnership, with its address at Two
North Riverside Plaza, Chicago, Illinois 60606, (hereinafter called "Landlord").
MANUFACTURERS HANOVER TRUST COMPANY, a New York banking corporation, its
successors and assigns, with its address at 270 Park Avenue, 38th Floor, New
York, New York 10017 (hereinafter called "Mortgagee"), and DRUG DEVELOPMENT
INVESTMENT CORP., a Texas corporation d/b/a id2, Inc. and id2  I, L.P., a Texas
limited partnership, with its address at 230 San Jacinto Center, 98 San Jacinto
Blvd., Austin, Texas  78701 (hereinafter jointly called "Tenant");

                                   RECITALS

     WHEREAS, Landlord and Tenant have entered into a certain Lease Agreement
dated March 17, 1993 (the "Lease") covering certain demised premises more fully
described in the Lease (the "Premises") located in Landlord's office building
situated in Lot 1, San Jacinto Center, an addition to the City of Austin, Texas,
according to the plat thereof recorded in Volume 89, Page 21 of the Plan Records
of Travis County, Texas (the "Property");

     WHEREAS, by Deed of Trust, Security Agreement, Fixtures Financing Statement
and Assignment of Rents and Leases dated December 13, 1991, and recorded in
Volume 11584, Page 0737 of the Real Property Records of Travis County, Texas
(the "Deed of Trust"), Landlord granted to Mortgagee a first mortgage lien and
security interest in the Property; and

     WHEREAS, Tenant desires to be assured of its continued enjoyment and
occupancy of the Premises subject to the provisions of the Lease and Mortgagee
desires to be assured of Tenant's attornment to any purchaser at a foreclosure
sale of the Property pursuant to the provisions of the Deed of Trust;

     NOW, THEREFORE, for and in consideration of the sum of Ten Dollars ($10.00)
and other good and valuable consideration, the mutual covenants and agreements
herein contained, the receipt and sufficiency of which is hereby acknowledged,
the parties hereto, intending to be legally bound hereby, covenant and agree as
follows:

 
     1.  The Lease and all estates, options, liens and charges therein contained
or created thereunder are and shall be subject and subordinate to the lien and
security interest of the Deed of Trust insofar as it affects the real property,
fixtures and personal property owned by Landlord of which the Premises forms a
part, and to all amendments, supplements, renewals, modifications,
consolidations, replacements and extensions thereof, to the full extent of the
indebtedness secured by the Deed of Trust.

     2.  In the event Mortgagee takes possession of the Premises as mortgagees-
in-possession or in the event of the Mortgagee or its Trustee or Substitute
Trustee forecloses the lien and security interest of the Deed of Trust, or in
the event Mortgagee accepts from Landlord or its successor or permitted assignee
a deed in lieu of foreclosure or otherwise, then and in any such event,
Mortgagee, for itself and its successor and assigns, shall not affect or disturb
Tenant's right to the use, quiet enjoyment and possession of the Premises in the
exercise of Mortgagee's rights under the Deed of Trust so long as Tenant is not
in default of the provisions of the Lease, which default has continued beyond
the expiration of any applicable grace or cure period provided in the Lease, if
any.

     3.  In the event that Mortgagee succeeds to the interest of Landlord under
the Lease and/or becomes the legal and beneficial owner in fee simple of the
Property, Mortgagee and Tenant shall be bound to one another, as landlord and
tenant, respectively, pursuant to the provisions of the Lease, and accordingly,
from and after the date on which Mortgagee succeeds to the interest of Landlord
under the Lease a/or becomes the legal and beneficial owner in fee simple of the
Property, Mortgagee, as landlord, shall have the rights and remedies of landlord
under the Lease and Tenant, as tenant, shall have the rights and remedies of
tenant under the Lease; provided, however, that Mortgagee shall not be:

          (a) liable for any act or omission of any prior landlord (including
the Landlord); or

          (b) subject to any offsets, counterclaims or defenses which Tenant
might have against any prior landlord (including the Landlord); or

          (c) bound by any base rent, additional rent or other sums for more
than one (1) month in advance which Tenant might have paid to any prior landlord
(including the Landlord) under the Lease; or

          (d) bound by any amendment or modification of the Lease made without
Mortgagee's prior written consent, if such prior written consent had been
required under the Lease; or

          (e) liable to return or otherwise account for any security deposit
deposited by Tenant with Landlord unless such security deposit has actually been
delivered by Landlord to Mortgagee; or

          (f) except to the extent expressly provided in the Lease, bound by or
liable for any contract or other agreement between Landlord and Tenant or
between Landlord and any other person or entity, which contract or agreement
pertains to the construction or installation of any leasehold improvements in
the Premises.

 
     4.  In the event that anyone (other than Mortgagee) acquires legal and
beneficial fee simple title to the Property upon the foreclosure of the lien and
security interest of the Deed of Trust, or upon the sale of the Property by
Mortgagee or its successors or assigns after foreclosing the lien and security
interest of the Deed of Trust or accepting from Landlord or its successor or
permitted assignee a deed in lieu of foreclosure of otherwise, Tenant shall not
terminate the Lease by reason thereof, but Tenant shall attorn to the new owner
of the Property and remain bound under the provisions of the Lease to the new
owner of the Property if the new owner agrees in writing to be bound to Tenant
under the provisions of the Lease.

     5.  In the event Mortgagee becomes a mortgagee-in-possession of the
Property or exercises its rights and remedies under the assignment of rents and
leases contained in the Deed of Trust and upon Mortgagee's written instructions
to Tenant, Tenant agrees to make all payments due under the Lease payable
directly to Mortgagee.

     6.  Tenant hereby agrees:

          (a) not to alter or modify the Lease in any respect without the prior
written consent of Mortgagee, if the Lease requires Mortgagee's prior written
consent to such alteration or modification;

          (b) to deliver to Mortgagee (or any successor in interest of Mortgagee
under the Deed of Trust) a duplicate copy of each notice of default delivered by
Tenant to Landlord under the Lease, at the same time as such notice is given to
Landlord;

          (c) that Tenant is now the sole owner of the leasehold estate created
by the Lease and shall not hereafter assign the Lease or sublet the Premises or
portion thereof without the prior written consent of Mortgagee and that
notwithstanding any such assignment or sublease, Tenant shall remain primarily
liable for the performance of the provisions of the Lease, except as otherwise
specifically provided in the Lease;

          (d) not to terminate the Lease by reason of any default of Landlord
without prior written notice of such default given by Tenant to Mortgagee and
the lapse thereafter of such time period as provided in the Lease for Landlord
to remedy such default, within which time period Mortgagee, at its option, may
remedy any such default; provided, however, that with respect to any default of
Landlord under the Lease which cannot be remedied within such time period, if
Mortgagee commences to cure such default within such time period and thereafter
diligently proceeds with such cure efforts, Mortgagee shall be permitted such
additional time (not to exceed ninety (90) days after said written notice from
Tenant to Mortgagee) as is reasonably necessary to complete the cure of such
default before Tenant shall seek to terminate the Lease;

          (e) not to prepay or anticipate the payment of base rent, additional
rent or other sums due under the Lease beyond one (1) month in advance;

          (f) to promptly certify, to the best of Tenant's knowledge, in writing
to Mortgagee, in connection with any proposed assignment of the Deed of Trust,
whether or not any default on the part of Landlord than exists under the Lease;
and

 
          (g) the Tenant shall not mortgage, encumber, pledge or grant a
security interest in the leasehold interest of Tenant under the Lease.

     7.   Landlord shall have the right as provided in the Deed of Trust, at its
          option, to subordinate the lien and security interest of the Deed of
          Trust to the Lease, without notice to or consent of Tenant.

     8.   This Agreement shall be binding upon the parties hereto and their
          respective heirs, executors, administrators, legal representatives,
          successors and assigns.

     9.   This Agreement shall not be amended or modified unless such amendment
          or modification is in writing executed by each of the parties hereto.

    10.  This Agreement shall be governed by an construed and enforced in
         accordance with the laws of the State of Texas.

    IN WITNESS WHEREOF, the undersigned have executed this Agreement as of the
date above written.


                                        LANDLORD:
 
                                        SAN JACINTO OFFICE TOWER LIMITED
                                        PARTNERSHIP, a Texas limited partnership
 
                                        By:  Equity Assets Management, Inc.
                                             its authorized agent
                                        
 
                                        By:_____________________________________
                                            RICHARD J. BERK
                                            VICE PRESIDENT
                                            OWNERSHIP REPRESENTATION
 

 
                                        MORTGAGEE:
 
                                        MANUFACTURERS HANOVER TRUST COMPANY.,
                                        a New York banking corporation
 
 
                                        By:_____________________________________
 
                                        Name:___________________________________
 
                                        Title:__________________________________
 


                                        TENANT:
 
                                        DRUG DEVELOPMENT INVESTMENT CORP.,
                                        a Texas corporation d/b/a id2, Inc.
 
 
                                        By:_____________________________________
                                            RICHARD J. HAWKINS
                                            CHAIRMAN OF THE BOARD OF DIRECTORS
 

                                        id2 - I, L.P., a Texas limited 
                                        partnership
 
                                        DRUG DEVELOPMENT INVESTMENT CORP.,
                                        a Texas corporation d/b/a id2, Inc., its
                                        sole general partner
 
 
 
                                        By:_____________________________________
                                           RICHARD J. HAWKINS
                                           CHAIRMAN OF THE BOARD OF DIRECTORS
 

 
THE STATE OF _________      (SECTION)

                            (SECTION)

COUNTY OF ___________       (SECTION)

     This instrument was acknowledged before on ____________________, 1993, by
Richard J. Berk, a Vice President of Equity Assets Management, Inc., as
authorized agent for SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, a Texas
limited partnership, on behalf of said limited partnership.


(SEAL)                                  ________________________________________
                                                   Notary Public in and for
                                                   The State of _________


                                        ________________________________________
                                                   Printed Name of Notary

                                        My Commission Expires:__________________


THE STATE OF _________      (SECTION)

                            (SECTION)

COUNTY OF ___________       (SECTION)

          This instrument was acknowledged before on ____________________,
19___, by ___________________________ President of MANUFACTURERS HANOVER TRUST
COMPANY, a New York banking corporation, on behalf of said banking corporation.

(SEAL)                                  ________________________________________
                                                   Notary Public in and for
                                                   The State of Texas


                                        ________________________________________
                                                   Printed Name of Notary

                                        My Commission Expires:__________________

 
THE STATE OF TEXAS          (SECTION)

                            (SECTION)

COUNTY OF TRAVIS            (SECTION)

          This instrument was acknowledged before on ____________________, 1993,
by Richard J. Hawkins, Chairman of the Board of Directors of DRUG DEVELOPMENT
INVESTMENT CORP., a Texas corporation d/b/a id2, Inc., on behalf of said
corporation.

(SEAL)                                  ________________________________________
                                                   Notary Public in and for
                                                   The State of Texas



                                        ________________________________________
                                                   Printed Name of Notary

                                        My Commission Expires:__________________


THE STATE OF TEXAS          (SECTION)

                            (SECTION)

COUNTY OF TRAVIS            (SECTION)

          This instrument was acknowledged before on ____________________, 1993,
by Richard J. Hawkins, Chairman of the Board of Directors of DRUG DEVELOPMENT
INVESTMENT CORP., a Texas corporation d/b/a id2, Inc., sole general partner of
id2  I, L.P., a Texas limited partnership, on behalf of said limited
partnership.

(SEAL)                                  ________________________________________
                                                   Notary Public in and for
                                                   The State of Texas


                                        ________________________________________
                                                   Printed Name of Notary

                                        My Commission Expires:__________________

 
                                 RIDER NO. 101

                            TO LEASE BY AND BETWEEN

           SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, AS LANDLORD

                                      AND

 DRUG DEVELOPMENT INVESTMENT CORP. D/B/A/ ID2, INC. AND ID2  I, L.P. AS TENANT

DEFINITIONS REGARDING CALCULATION OF TENANT'S OCCUPANCY COSTS AND CALCULATION OF
NET RENTABLE AREA.

     1.   For purposes of this Lease, the term "Tenant's Proportionate Share"
shall mean the percentage obtained by dividing the number of square feet of Net
Rentable Area in the Premises by 391,741 square feet of Net Rentable Area
(hereby stipulated as being the total of the number of square feet of Net
Rentable Area in all office space in the Building).

     2.   For purposes of the Lease, the term "Operating Costs" shall mean any
and all costs, expenses and disbursements of every kind and character (subject
to the limitations set forth below) which Landlord shall incur, pay or become
obligated to pay in connection with the ownership of any estate or interest in,
operating, maintenance, cleaning, repair, replacement, and security of the
Building, determined in accordance with generally accepted accounting principles
consistently applied, including but not limited to the following:

          (a) Wages and salaries of all employees engaged in the operation,
repair, replacement, maintenance and security of the Building and Land,
including taxes, insurance and benefits relating thereto.

          (b) All supplies, equipment and materials used in the operation
cleaning, maintenance, repair, replacement, and security of the Building and
Land.

          (c) Annual cost of all capital improvements made to the Building and
Land which, although capital in nature, can reasonably be expected to reduce the
normal operating costs thereof, together with all capital improvements made to
the Building and Land in order to comply with any statutes, rules, regulations
or directives promulgated by any governmental authority relating to access for
the disabled, energy, conservation, public safety or security, each, as
amortized over the useful life of such improvements by Landlord for federal
income tax purposes.

          (d) Cost of all utilities other than the cost of electricity supplied
to tenants of the Building and Land which is separately reimbursed to Landlord
by such tenants.

          (e) Cost of all cleaning, maintenance and service agreements on
equipment, including alarm service, window cleaning, elevator maintenance and
janitorial service.

          (f) Cost of all insurance related to the Building, plus any
deductible, including without limitation, the cost of casualty and liability
insurance applicable to the 

 
Building and Landlord's personal property used in connection therewith and the
cost of rent loss or business interruption insurance; provided however, if such
insurance is provided in the form of master policies, then an equitable portion
of the premiums therefor shall be included herein.

          (g) All taxes and assessments and governmental charges whether
federal, state, county, or municipal and whether they be by taxing districts or
authorities presently taxing or by others, subsequently created or otherwise,
and any other taxes and assessments attributable to the Building and the Land,
including any sales or uses taxes associated with materials and services but
excluding, however, Federal and State taxes on income.

          (h) Cost of repairs, replacement, cleaning and general maintenance of
the Building and Land.

          (i) Cost of cleaning, service or maintenance contracts with
independent contractors, and the equipment therein, for the operation, cleaning,
maintenance, repair, replacement, landscaping or security of the Building and
the Land.

          (j) A Management Fee in the amount of four (4%) of the gross revenues
received by Landlord with respect to the Building and Land.

          (k) All landscaping expenses and costs of repairing, resurfacing and
striping of the parking areas.

     There are specifically excluded from the definition of the term "Operating
Costs" expenses for capital improvements made to the Building, other than
capital improvements described in subparagraph (c) above and except for items
which, though capital for accounting purposes, are properly considered
maintenance and repair items, such as painting of common areas, replacement of
carpet in elevator lobbies, and the like; any amounts for which Landlord becomes
liable as a result of any claims against Landlord arising from Landlord's actual
or alleged negligence in the ownership and operation of the Land and the
Building; any general overhead and administrative expense of Landlord to the
extent not directly attributable to the Land or the Building; any penalty or
fine incurred by Landlord; rental under any and all ground or underlying leases;
any wages, salaries, compensation or contract or subcontract expenses of persons
not directly involved in the management, operation or repair of the Building;
any expenses for which Landlord is otherwise paid or reimbursed; legal,
accounting, inspection, survey or other fees incurred in connection with any
financing or refinancing obtained by landlord, or which are otherwise not
incurred primarily and directly in connection with the management, operation,
maintenance or repair of the Building; contributions to any sinking fund for the
repair or replacement of equipment or facilities in the Building unless such
sinking fund is used to pay capital items which would otherwise be passed
through and such expenses paid out of the sinking fund are not included in
Operating Costs at the time that they are paid, excess electricity costs
specifically paid by Tenant pursuant to Paragraph 9 of this Lease; expenses for
repair, replacements and general maintenance paid by proceeds of insurance or by
Tenant or other third parties, and alterations attributable solely to tenants of
the Building other than Tenant; interest, amortization or other payments on
loans to Landlord; depreciation of the Building; leasing commissions, legal
expenses and other expenses incurred in connection with negotiations or disputes
with other tenants or occupants or prospective tenants or occupants of the
Building; 

 
and income, excess profits or franchise taxes or other such taxes imposed on or
measured by the income of Landlord from the operation of the Building.

     With respect to any Calendar Year or partial Calendar Year during the Lease
Term in which the Building is not occupied to the extent of one hundred percent
(100%) of the rentable area thereof, the Operating Costs for such period shall,
for the purposes hereof, be increased to the amount which would have been
incurred had the Building been occupied to the extent of one hundred percent
(100%) of the rentable area thereof and building standard services had been
provided through the entire Building provided that Tenant's Proportionate Share
shall never be calculated so as to the result in a recovery by Landlord of more
than the actual Operating Costs for such period.  Moreover, if by reason of
vacancies in the Building, the calculation of Tenant's Proportionate Share would
result in an amount that is increased beyond that which would apply if the
Building were fully occupied, Tenant's Proportionate Share shall be limited to
that which would reasonably apply based on full occupancy.

     3.   The term "Net Rentable Area," as used herein, shall refer to (i) in
the case of a floor leased to a single tenant, Net Useable Area (defined below)
plus a pro rate allocation of the square footage of the General Common Areas
(defined below), and (ii) in the case of a floor leased to more than one tenant,
Net Useable Area, plus a pro rata allocation of the square footage of the
General Common Areas and a pro rata allocation of the Square footage of the On-
Floor Common Areas. No deductions from Net Rentable Area shall be made for
columns or projections necessary to the Building.

     4.   The term "Net Useable Area," as used herein, shall refer to (i) in the
case of a floor leased to a single tenant, all floor area measured from the
inside surface of the opposite outer glass line, excluding only Service Areas
and General Common (defined below), and (ii) in the case of a floor leased to
more than one tenant, all floor area within the inside surface of the outer
glass line of the Building enclosing the Premises and measured to the midpoint
of demising walls (i.e., walls separating the Premises from area leased to or
held for lease to other tenants, from On-Floor Common Areas (defined below), and
from General Common Areas, excluding only Service Areas (defined below).

     5.   "Service Areas" shall mean the areas within (and measured from the
midpoint of the walls enclosing) the Building's stairs, fire towers, elevator
shafts, flues, vents, stacks, pipe shafts and vertical ducts.  Areas for the
specific use of Tenant and installed at the request of Tenant, such as special
stairs or elevators, are not included within the definition of Service Areas.

     6.   "General Common Areas" shall mean those areas within (and measured
from the midpoint of the walls enclosing) the Building's elevator machine rooms,
main mechanical and electrical rooms, public lobbies, management office and
other areas not leased or held for lease within the Building but which are
necessary or desirable for the proper utilization of the Building or to provide
customary services to the Building. The allocation of the square footage of the
General Common Areas shall be equal to the total General Common Areas within the
Building multiplied by a fraction, the numerator of which is the Net Rentable
Area of the Leased Premises (excluding only the allocation of the General Common
Areas) and the denominator of which is the Net Rentable Area (excluding only the
General Common Areas) of all office space leased or held for lease in the
Building.

 
     7.   "On-Floor Common Areas" shall mean all areas within (and measured from
the midpoint of the walls enclosing) public corridors, elevator foyers,
restrooms, mechanical rooms, janitor closets, telephone and equipment rooms, and
other similar facilities for the use of all tenants on the floor on which the
leased premises are located.  In the case of a floor leased to more than one
tenant, the allocation of the square footage of the On-Floor Common Areas on
said floor shall be equal to the total On-Floor Common Areas on said floor
multiplied by a fraction, the numerator of which is the Net Rentable Area of
the portion of the leased premises (excluding the allocation of the General
Common Areas and excluding the allocation of the On-Floor Common Areas) and the
denominator of which is the Net Rentable Area (excluding the allocation of the
General Common Areas and excluding the allocation of the On-Floor Common Areas)
of all office space leased or held for lease on said floor.

     8.   "Calendar Year" shall mean the twelve month period beginning on
January 1 and ending on December 31 of the applicable calendar year.

     9.   "Lease Year" shall mean, respectively, the twelve-month period
beginning on the Commencement Date and on each successive anniversary of the
Commencement Date thereafter during the Lease Term.  Each such Lease Year shall
end on the day preceding the next anniversary on the Commencement Date.

 
                                 RIDER NO. 102

                            TO LEASE BY AND BETWEEN

           SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, AS LANDLORD

                                      AND

 DRUG DEVELOPMENT INVESTMENT CORP. D/B/A/ ID2, INC. AND ID2  I, L.P. AS TENANT


PARKING

       Subject to the further provisions of this Rider No. 102, at all times
during the Lease Term and any renewals or extensions thereof, and conditioned
upon this Lease and any renewals or extensions thereof being in full force and
effect and there being no default under this Lease as defined therein, Landlord
hereby agrees to make available to Tenant, and Tenant hereby agrees to pay for
and take, during the Lease Term, and any extension or renewal thereof, the
reserved and unreserved parking spaces for automobiles in the Building's parking
garage as provided for in the Basic Lease Information.

       Tenant shall pay for such parking spaces at the rates and in the manner
provided for in the Basic Lease information.  Tenant shall not have the right to
more reserved or unreserved parking spaces than the number set forth above.  All
parking space payments shall be payable to the independent contractor which
Landlord hires from time to time to operate the parking garage unless otherwise
directed by Landlord.  With respect to unreserved spaces, Tenant shall not be
assigned to designated parking stalls, but shall be permitted to use whatever
stalls are available, on unassigned and unreserved, first-come, first-served
basis in areas of the parking garage designated by Landlord.

       At Landlord's request, Tenant and its employees shall enter into a
parking agreement with Landlord and/or its garage operator regarding the parking
spaces available to Tenant hereunder.  Additionally, Landlord and its garage
operator shall have the right from time to time to promulgate reasonable rules
and regulations regarding the parking spaces available to Tenant hereunder and
others, including but not limited to, the flow of traffic to and from various
parking areas, angles and direction of parking and the like.  Tenant agrees to
comply with such rules and regulations (and reasonable additions and amendments
thereto) as Landlord and its garage operator may promulgate from time to time.
In the event of any conflict between the terms and provisions of the parking
agreement and the terms and provisions of the rules and regulations, the terms
and provisions of the rules and regulations shall control.  In the event of any
conflict between the terms and provisions of the parking agreement and/or the
rules and regulations and the terms and provisions of this Lease, the terms and
provisions of the Lease shall control.

       Landlord and its garage operator will not be responsible for money,
jewelry, or other personal property lost or stolen in or from the parking
garage, uncovered parking areas, or public areas regardless of whether such loss
or theft occurs when the garage or such areas are locked or otherwise secured
against entry or not.

 
                                  EXHIBIT "C"

                       ACCEPTANCE OF PREMISES MEMORANDUM

     THIS ACCEPTANCE OF PREMISES MEMORANDUM (this "Memorandum") is entered into
on this ____ day of ______ 1993, by and between SAN JACINTO OFFICE TOWER LIMITED
PARTNERSHIP, a Texas limited partnership, as Landlord ("Landlord"), and DRUG
DEVELOPMENT INVESTMENT CORP., a Texas corporation d/b/a id2  L.P., a Texas
limited partnership, jointly as Tenant ("Tenant").  Unless otherwise defined
herein, all capitalized terms used herein shall have the same meaning ascribed
to such terms in the Lease (as hereinafter defined).

                                  WITNESSETH:

     WHEREAS, as of June 1, 1993, Landlord and Tenant entered into that certain
Office Space Lease (the "Lease") whereby Landlord leased certain Premises
located in the Building to Tenant pursuant to certain terms and provisions more
particularly described therein;

     WHEREAS, certain Leasehold Improvements to the Premises have been
constructed and installed for the benefit of Tenant in accordance with the Space
Plan and the Construction Documents and upon the terms and conditions set forth
in the Work Letter; and

     WHEREAS, as provided in Paragraph 7 of the Lease, Tenant desires to take
possession of and accept the Premises subject to the terms and provisions
hereof;

     NOW, THEREFORE, for and in consideration of the mutual covenants and
agreements contained herein and in the Lease, and other good and valuable
consideration, Landlord and Tenant hereby expressly covenant, acknowledge, and
agree as follows:

     1.  Except for the specific items described in the "punch list" attached
hereto as Exhibit "C-1" and incorporated herein by reference for all purposes,
which Landlord shall endeavor to remedy within ___ (__) business days hereof,
Landlord has fully completed the Leasehold Improvements, alterations or
modifications to the Premises in accordance with the Space Plan and the
Construction Documents and approved Change Orders, if any, and pursuant to the
Work Letter.

     2.  The Premises are tenantable and ready for immediate occupancy by
Tenant, Landlord has no further obligation to install or construct any Leasehold
Improvements, modifications or alterations to the Premises (except as described
in Exhibit "C-1" attached hereto) and, except as described in Exhibit "C-1"
attached hereto, the Premises are satisfactory to Tenant in all respects.

     3.  The Commencement Date of the Lease is July 19, 1993.  Pursuant to the
provisions of the Lease, the first monthly installment of Base Rent
[became/shall become] due and payable on July 19, 1993.

     4.  The expiration date of the Lease shall be July 18, 1998.

     5.  The Premises contains approximately 3,337 square feet of Net Rentable
Area.

 
     6.  Base Rent:  Base Rent for the Lease Term shall be $2,433.23 per month,
calculated at $8.75 per annum per square foot of Net Rentable Area of the
Premises.

     7.  Except as specifically set forth herein, as of the date of this
Memorandum, the Lease has not been modified, altered, supplemented, superseded,
or amended in any respect.

     8.  All terms, provisions, and conditions of the Lease are and remain in
full force and effect, and are hereby expressly ratified, confirmed, restated,
and reaffirmed in each and every respect.

     IN WITNESS WHEREOF, this Memorandum is executed by Landlord and Tenant on
the date first set forth above.

                              LANDLORD:

                              SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, a
                              Texas Limited Partnership

                              By:  Equity Assets Management, Inc., its
                                   authorized agent

                              By:   /s/ Kim Koehn
                                    ------------------------------------------
                              Name:   Kim Koehn
                              Title:  Vice President, Ownership Representation

                              ADDRESS:

                              San Jacinto Office Tower Limited Partnership
                              300 San Jacinto Center
                              98 San Jacinto Blvd.
                              Austin, Texas 78701
                              Attn:  Property Manager

                              TENANT:

                              DRUG DEVELOPMENT INVESTMENT CORP., a Texas
                              corporation d/b/a id2, Inc., a Texas corporation

                              By:   /s/ Richard J. Hawkins
                                    ------------------------------------------
                              Name:    Richard J. Hawkins
                              Title:   Chairman of the Board of Directors

 
                                    ID2 -- L.L.P., A TEXAS LIMITED PARTNERSHIP

                              By:   /s/ Richard J. Hawkins
                                    ------------------------------------------

                              Name:  Richard J. Hawkins

                              Title: Chairman of the Board of Directors

                              ADDRESS:

                              230 San Jacinto Center
                              98 San Jacinto Blvd.
                              Austin, Texas 78701
                              Attn: Richard J. Hawkins

     THE STATE OF TEXAS  )

                         )

     COUNTY OF TRAVIS    )

     This instrument was acknowledged before me on January 19, 1994, by Kim
Koehn, a Vice President of Equity Assets Management, Inc., as authorized agent
for SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, a Texas limited partnership,
on behalf of said limited partnership.


     [SEAL]                             /s/ Donann Scott
                                   -------------------------------------
                                        Notary Public in and for

                                        The State of Texas


                                        Donann Scott
                                   -------------------------------------

                                        Printed Name of Notary


                                   My Commission Expires:   9/28/96
                                                          --------------

 
     THE STATE OF TEXAS  )

                         )

     COUNTY OF TRAVIS    )

          This instrument was acknowledged before me on January 5, 1994 by
Richard J. Hawkins, Chairman of the Board of Directors of DRUG DEVELOPMENT
INVESTMENT CORP., a Texas corporation d/b/a id2, Inc. on behalf of said
corporation.

     [SEAL]                             /s/ Brenda K. Hindsman          
                                   -------------------------------------
                                        Notary Public in and for

                                        The State of  Texas


                                             Brenda K. Hindsman
                                   -------------------------------------

                                        Printed Name of Notary


                                   My Commission Expires: December 2, 1995
                                                          ----------------

 
     THE STATE OF TEXAS  )

                         )

     COUNTY OF TRAVIS    )


          This instrument was acknowledged before me on January 5, 1994, by
Richard J. Hawkins, Chairman of the Board of Directors of Drug Development
Investment Corp., a Texas corporation d/b/a id2, Inc. sole general partner of
id2- L.L.P., a Texas limited partnership, on behalf of said limited partnership.


     [SEAL]                             /s/ Brenda K. Hindsman          
                                   -------------------------------------
                                        Notary Public in and for

                                        The State of Texas


                                        Brenda K. Hindsman
                                   -------------------------------------

                                        Printed Name of Notary


                                   My Commission Expires:   December 2, 1995
                                                            ----------------

 
                                 EXHIBIT "C-1"

                                        

                                  PUNCH LIST


        All punch list items have been completed.

 
                               GUARANTY OF LEASE

     WHEREAS, DRUG DEVELOPMENT INVESTMENT CORP. d/b/a id2, Inc. and id2--L.L.P.
(jointly, "Tenant") have entered into that certain Lease Agreement (the "Lease")
dated March 17, 1993 with SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP
("Landlord"); and

     WHEREAS, Landlord was not willing to enter into the Lease without the
receipt of this Guaranty executed and acknowledged by the undersigned;

     NOW, THEREFORE, to induce Landlord to execute the Lease, as a material
consideration and inducement therefore (recognizing without the execution and
delivery of this Guaranty, Landlord would not be willing to enter into the Lease
Amendment), and recognizing the benefit of the Lease to the undersigned, the
undersigned hereby agree as follows:

     The undersigned (herein called "Guarantors" whether one or more) hereby
unconditionally, jointly and severally guarantee observance by Tenant of all the
monetary obligations, duties, covenants, agreements and conditions provided in
the Lease, as same may hereafter be amended from time to time, to be observed by
Tenant during the term of the Lease (including specifically and without limiting
the generality of the foregoing, payment by Tenant of all rental and other
amounts and damages of whatsoever kind or nature which may be or become due from
Tenant under the terms of or in connection with the Lease).  This guaranty is
unconditional, and the liability of Guarantors shall be absolute, in the same
manner as if Guarantors, jointly and severally, were named in and had signed the
Lease as "Tenant" thereunder.  Guarantors agree that bankruptcy, insolvency,
lack of corporate capacity or any other disability or impediment against
enforcement of full liability of Tenant named in the Lease shall in no way
impair or affect Guarantors' liability and obligation hereunder, and, without
limitation of the foregoing.  Guarantors agree that in the event that Tenant
shall become insolvent or shall be adjudicated a bankrupt, or shall file a
petition for reorganization, arrangement or other relief under any present or
future provisions of the Bankruptcy Code, or if such a petition be filed by
creditors of Tenant, or if Tenant shall seek a judicial readjustment of the
rights of its creditors under any present or future federal or state law or if a
receiver of all or part of Tenant's property and assets is appointed by any
state or federal court, no such proceeding or action taken therein shall modify,
diminish or in any way affect the liability of Guarantors under this guaranty,
and the liability of Guarantors for the Tenant's obligations under the Lease
shall be of the same scope as if Guarantors had themselves, jointly and
severally, executed the Lease, and no "rejection" and/or "termination" of the
Lease in any of the proceedings referred to above shall be effective to limit,
release and/or terminate the continuing liability of Guarantors to Landlord
under this guaranty with respect to the Lease and such liability of Guarantors
shall be unaffected by any such "rejection" and/or "termination" in said
proceedings.  It shall not be necessary or required in order to maintain and
enforce Guarantors' liability hereunder that demand be made upon Tenant or that
action be commenced or prosecuted against Tenant or that any effort be made to
enforce the liability or responsibility of Tenant for performance of its
obligations or duties under or in connection with the Lease, and it shall not be
required that Tenant or any other party liable on such lease be joined in any
action brought against Guarantors for enforcement of Guarantors' liability and
responsibility under this guaranty or that judgment have theretofore bee
obtained against Tenant or any other party liable therefor on or in connection
with any such claim.  Guarantors agree that no waiver by Landlord 

 
or forbearance or delay by Landlord in asserting or enforcing any rights or
remedies of Landlord against or with respect to Tenant or any other party who
may be or becomes responsible for performance of any of such Tenant's
obligations or duties shall in any affect, impair or release Guarantors'
liability hereunder. Likewise, Guarantors agree that no assignment or subletting
of the Lease or of all or any part of the leased premises by such Tenant shall
in any way impair, affect or release Guarantors' liability hereunder. Guarantors
expressly waive and agree that no notice of default by Tenant or other notice or
demand need be given by Landlord to Guarantors as a condition of maintaining or
enforcing Guarantors' liability and obligations under this guaranty. Guarantors
expressly agree that no notice of amendment or modification of the Lease need be
given by Landlord or Tenant to Guarantors as a condition of maintaining or
enforcing Guarantors' liability and obligations under this guaranty. Guarantors
expressly agree that any amendment or modification of the Lease may be made by
Landlord and Tenant, as provided in such lease, with or without the approval of
Guarantors, and that any such amendment will be deemed part of the Lease for
purposes of this guaranty. Likewise, Guarantors agree that Landlord's release or
subordination or failure or delay to enforce or seek to realize upon any
security now or hereafter held or acquired by Landlord for performance of any of
the obligations or duties of Tenant under or in connection with the Lease shall
in no way impair, affect or release Guarantors' liability hereunder, and that
Landlord's action (at Landlord's election) in termination such lease or in
taking or retaking possession of the leased premises as therein provided
following default by Tenant shall not release or impair Guarantors' liability
hereunder and that no notice of such termination or of such entry or re-entry by
Landlord need be given to Guarantors. Without limitation of anything herein to
the contrary, Guarantors agree that any waiver by Lessor or forbearance or
failure or delay by Lessor in liability of any of the other Guarantors
hereunder.

     NOTWITHSTANDING ANYTHING HEREIN TO THE CONTRARY, THE MAXIMUM LIABILITY OF
GUARANTOR HEREUNDER SHALL BE LIMITED TO $75,807.00, PLUS ALL COSTS, INCLUDING
WITHOUT LIMITATION REASONABLE ATTORNEYS' FEES, INCURRED IN ENFORCING THIS
GUARANTY (THE "GUARANTEED AMOUNT"). THE GUARANTEED AMOUNT SHALL BE REDUCED BY
$1,263.46 FOR EACH FULL MONTH OF THE LEASE TERM IN WHICH TENANT PERFORMS ALL OF
ITS MONETARY OBLIGATIONS UNDER THE LEASE.

     This guaranty shall be enforceable and shall be performed in Travis County,
Texas.

     WITNESS the execution hereof effective as of the date of execution and
delivery of the Lease.

                                                /s/ Richard J. Hawkins
                                        ---------------------------------------
                                        Richard J. Hawkins

                                        ADDRESS:

                                        230 San Jacinto Center
                                        98 San Jacinto Blvd.
                                        Austin, Texas 78701

 
THE STATE OF TEXAS  )
                    )
COUNTY OF TRAVIS    )

     This instrument was acknowledged before me on the 1st day of April, 1993,
by Richard J. Hawkins.


[SEAL]                                  /s/ Lauren K. Baisdon            
                                   -------------------------------------
                                        Notary Public in and for
                                        The State of Texas

                                        Lauren K. Baisdon
                                   -------------------------------------
                                        Printed Name of Notary

                                   My Commission Expires: January 26, 1995
                                                          ----------------

 
                                   EXHIBIT I

                AGREEMENT REGARDING LENDER'S SECURITY INTEREST
                       IN THE TENANT'S PERSONAL PROPERTY

     THIS AGREEMENT is entered into as of the _____ day of __________, 199__, by
and between ______________________________ ("Landlord"),
______________________________ ("Tenant") and ______________________________
("Lender"), with reference to the following facts:

     A.  Landlord and Tenant have heretofore entered into a written lease
("Lease") dated ____________________, for certain premises (the "Leased
Premises") located in that certain office building known as ____________________
(the "Building") in ____________________.

     B.  Tenant desires to borrow money from Lender in the principal sum of
____________________ ($__________) (the "Loan").

     C.  Lender desires to obtain a security interest in the Tenant's personal
property (the "Collateral") located within the Leased Premises and/or described
in Exhibit A attached hereto until such Loan is repaid.

     D.  Landlord is willing to subordinate its rights in the Collateral to the
rights of Lender's security interest upon the terms and conditions hereinafter
set forth.

     NOW, THEREFORE, in consideration of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

     1.  The only property affected by this agreement is that Collateral
specifically listed on Exhibit A attached hereto.  Any property not described in
Exhibit A shall not be subject to the terms of this Agreement, and Landlord
shall be entitled, to the extent provided by the Lease and by law, to exercise
any lien, right or remedy against such other property.

     2.  Lender acknowledges that it has no security interest in any property
located in, or about the Leased Premises other than the Collateral listed on
Exhibit A.

     3.  Notwithstanding anything to the contrary contained in the Lease, until
such time as Tenant repays in full to Lender the Loan which is secured by the
Collateral, the Collateral shall remain the personal property of Tenant subject
to the security interest of Lender.  Lender shall notify Landlord when the
obligations of the Tenant to repay the Loan have been satisfied and discharged.

     4.  Landlord does hereby subordinate any and all liens, claims or rights in
and to the Collateral to the security interest of Lender in the Collateral;
provided, however, that this subordination shall not prevent Landlord from
exercising any right or remedy against Tenant to which Landlord may be entitled
under the terms of the Lease or as may be provided by applicable law, nor shall
it prevent Landlord from exercising any lien on any property of Tenant,

 
including the Collateral, or enforcing any judgment by levying upon any property
of Tenant, including the Collateral, so long as Landlord recognizes Lender's
prior right to the Collateral, the provisions of any security and other
agreements between Tenant and Lender shall at all times be subject and
subordinate to all covenants, terms and conditions of the Lease and all of
Landlord's rights thereunder.

     5.  Lender can enter the Leased Premises for purpose of removal of the
Collateral only if:

          (a) permitted by the Loan Agreement between Lender and Tenant;

          (b) Lender gives Landlord ten (10) days prior written notice;

          (c) Lender enters the Leased Premises for purpose of removal of the
Collateral at such time and in such manner as Landlord reasonably may determine
so as to minimize disruption to the operation of the Building;

          (d) Lender and Tenant agree, jointly and severally, promptly to repair
any damage to the Leased Premises or to the Building caused by the removal of
the Collateral or, if Landlord shall, in its sole discretion, elect to make such
repairs, to pay to Landlord upon demand the costs and expenses incurred in
connection therewith;

          (e) Tenant and Lender agree, jointly and severally, to restore the
Leased Premises to the condition the Leased Premises were in prior to the
installation of the Collateral;

          (f) there shall be no display nor private sale of the Collateral on
the Leased Premises or in the Building;

          (g) Lender hereby indemnifies Landlord for any claim, liability or
expense (including reasonable attorneys' fees) arising out of or in connection
with Lender's removal of the collateral and Lender's entry and activities upon
the Leased Premises and the Building.

     6.  Lender agrees that any modification or alteration of any document
relating to the Loan or the Collateral or any other provision which may affect
the rights of Landlord in and to the Collateral, shall not be effective against
Landlord unless consented to in writing by Landlord.

     7.  If Landlord shall fail to demand strict compliance with any provision
hereof, such failure shall not constitute a waiver of any right or remedy to
which Landlord may be entitled.

     8.  If Tenant should be in default under the terms of the Lease, and such
default results in (a) the termination of the Lease or (b) claims by Landlord
for rent due, Lender shall submit to Landlord within ten (10) days after
Landlord's demand therefor, a certified statement showing:

               (i)   the original amount of funds supplied by Lender to Tenant;

               (ii)  the amount paid by Tenant to date; and

               (iii) the amount due from Tenant to Lender.

 
     In the event Lender sells the Collateral to satisfy claims against Tenant,
all funds derived from the sale of the Collateral, to the extent that such funds
are in excess of the amount owed to the Lender, shall belong to Landlord to
satisfy any claim which Landlord may have.

     9.  Landlord shall have the right, but not the obligation, to cure any
default by Tenant under any agreement between Lender and Tenant concerning the
Collateral.  Lender agrees to notify Landlord in writing of any default on the
part of Tenant under its agreement with Tenant concerning the Collateral and
further agrees that Lender shall not exercise any of its rights with respect to
the Collateral unless Landlord has received the aforesaid notice and ha snot,
within thirty (30) days after the date thereof, cured such default or if the
default cannot be cured within thirty (30) days, has not commenced curing and is
not diligently prosecuting the cure of Tenant's default; provided, however, that
nothing contained in this Agreement shall require Landlord to cure any such
default or otherwise to perform the obligations of Tenant to Lender.

     10.  This Agreement contains the entire understanding between the parties
hereto. Any modification shall be effective only if in writing and signed by the
parties hereto.

     11.  Landlord's address for notices is:

          Equity Assets Management, Inc.
          2 North Riverside Plaza, Suite 1601
          Chicago, Illinois  60606
          Attn:_____________________

          With a copy to:

          Rosenberg & Liebentritt, P.C.
          Suite 1602
          Two North Riverside Plaza
          Chicago, Illinois  60606
          Attn:_____________________

          Tenant's address for notices is:

          [FROM LEASE NOTICE PROVISION]

          ______________________________ 

          ______________________________ 

          ______________________________  
 
          Attention:_________________

          Lender's address for notices is:

          ______________________________  

          ______________________________ 

          ______________________________  
 
          Attention:_________________

 
     12.  This Agreement shall be governed by and construed in accordance with
the laws of the state in which the Building is located.

     13.  This Agreement shall be binding upon and inure to the benefit of the
heirs, executors, administrators, successors and assigns of the respective
parties hereto.

     IN WITNESS WHEREOF, the parties hereto have set their hands below.

                                        LANDLORD

                                        EQUITY ASSETS MANAGEMENT, INC. AS AGENT

                                        By:____________________________________
                                        Title:

                                        TENANT

                                        ________________________________________

                                        By:_____________________________________
                                        Title:

                                        LENDER

                                        _______________________________________ 

                                        By:____________________________________
                                        Title:


                        FIRST AMENDMENT TO OFFICE LEASE

     WHEREAS, SAN JACINTO OFFICE TOWER LIMITED PARTNERSHIP, a Texas limited
partnership ("Landlord"), and DRUG DEVELOPMENT INVESTMENT CORP., a Texas
corporation d/b/a id2-I, L.P., a Texas limited partnership (jointly, "Tenant"),
entered into that certain office Space Lease (the "Lease") dated March 17, 1993,
concerning approximately 3,188 square feet of Net Rentable Area (the "Initial
Premises") on the 2nd floor of that certain office building commonly referred to
as San Jacinto Center (the "Building"); and

     WHEREAS, the Initial Premises has been relocated to that certain area on
the 4th floor of the Building containing approximately 3,337 square feet of Net
Rentable Area (the "New Premises"), commonly referred to as Suite 430; and

     WHEREAS, Landlord and Tenant wish to amend the Lease as hereinafter
provided.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby agree
as follows:

     14.  From and after the date of this Amendment, (a) the New Premises shall
be deemed to be the Premises under the Lease for all purposes and therefore all
references in the 

 
Lease to the Premises shall be deemed to be references to the New Premises and
(b) Tenant shall have no further right, title or interest in and to the Initial
Premises.

     15.  From and after the date of this Amendment, the following items of the
Basic Lease Information contained in the Lease are hereby amended to read in
full as follows:

     Address to Tenant:  430 San Jacinto Center
                         98 San Jacinto Boulevard
                         Austin, Texas 78701

     Premises           Suite No. 430, which is located in the office building
                        commonly referred to as San Jacinto Center (the
                        "Building"), which has been constructed on the land (the
                        "Land") located on Lot 1 of San Jacinto Center, an
                        addition to the City of Austin, Texas, according to the
                        Plat thereof recorded in Volume 89, Page 21 of the Plat
                        Records of Travis County, Texas, which Premises are
                        outlined on the Plan attached hereto as Exhibit "A."

     Net Rentable Area
     Of the Premises:   Approximately 3,337 square feet

     Base Rent:         Base Rent for the Lease Term shall be $2,433.23 per
                        month, calculated at $8.75 per annum per square foot of
                        Net Rentable Area of the Premises, all as adjusted
                        pursuant to Exhibit "C" attached hereto and incorporated
                        herein.

     Estimate of Tenant's Occupancy Costs (as defined in the Lease) for the
     first Calendar Year (as defined in the Lease):

          $1,996.64 per month, calculated at $7.18 per annum per square foot of
          Net Rentable Area of the Premises

     16.  Tenant's address for notices as set forth in Paragraph 35(c) of the
Lease is hereby amended to read in full as follows:

               430 San Jacinto Center
               98 San Jacinto Boulevard
               Austin, Texas 78701
               Attention:  Richard J. Hawkins

     17.  The cancellation fee set forth in Paragraph 54(a)(ii) is hereby
changed from "$8,464.14" to "$8,859.74."

     18.  Exhibit "A" attached hereto shall replace for all purposes the Exhibit
"A" attached to the Lease.

     19.  Any other capitalized term not expressly defined in this Amendment
shall have the meaning set forth in the Lease.

     20.  The Lease as amended hereby is hereby ratified and affirmed.  In the
event of any conflict between the Lease and this Amendment, this Amendment shall
control.

 
     EXECUTED as of June 1, 1993.

                                    SAN JACINTO OFFICE TOWER LIMTIED PARTNERSHIP

                                    By:  Equity Assets Management, Inc.,
                                         its authorized agent

                                         By:/s/ Kim Koehn
                                           -------------------------------------
                                           Kim Koehn
                                           Vice-President, Ownership
                                           Representation

                                                                      "LANDLORD"

                                    DRUG DEVELOPMENT INVESTMENT CORP., a Texas
                                    corporation d/b/a id2, Inc.

                                    By:  Drug Development Investment Corp.
                                         a Texas corporation d/b/a id2, Inc.,
                                         its sole general partner

                                         By: /s/ Richard J. Hawkins
                                           -------------------------------------
                                           Richard J. Hawkins, Chairman of the
                                           Board of Directors

                                                                        "TENANT"

 
                    SECOND AMENDMENT TO OFFICE SPACE LEASE


     THIS SECOND AMENDMENT TO OFFICE SPACE LEASE (this "Amendment") is entered
into by and between EOP-SAN JACINTO LIMITED PARTNERSHIP, a Texas limited
partnership ("Landlord") and DRUG DEVELOPMENT INVESTMENT CORP., a Texas
corporation d/b/a id2, Inc. and id2-I, L.P., a Texas limited partnership
(jointly, "Tenant").  Unless otherwise defined herein, all capitalized terms
used herein shall have the same meaning ascribed to such terms in the Lease (as
hereinafter defined).

     WHEREAS, Landlord (as successor-in-interest to SAN JACINTO OFFICE TOWER
LIMITED PARTNERSHIP, a Texas limited partnership) and Tenant are parties to that
certain Office Space Lease dated March 17, 1993, as amended by that certain
First Amendment to Office Lease dated June 1, 1993 under which First Amendment
Tenant relocated to new space in the Building (said Office Space Lease, as
amended, being hereinafter referred to as the "Lease"); and

     WHEREAS, Landlord and Tenant have agreed to expand the Premises so that
Tenant shall lease from Landlord the First Additional Premises (defined below);
and

     WHEREAS, Landlord and Tenant have agreed to extend the Term of the Lease;
and

     WHEREAS, Landlord and Tenant wish otherwise to amend the terms of the Lease
as hereinafter provided;

     NOW, THEREFORE, for and in consideration of the mutual agreements and
covenants set forth herein, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Landlord and Tenant do
hereby expressly agree, covenant, and acknowledge as follows:

     21.  In consideration of the obligation of Tenant to pay rent with respect
to the First Additional Premises and in consideration of the terms, covenants
and conditions of the Lease, as amended hereby, Landlord hereby demises and
leases to Tenant and Tenant hereby takes from Landlord the First Additional
Premises, to have and to hold commencing on the First Additional Premises
Commencement Date (defined below) and continuing for the remainder of the Lease
Term, all upon the terms and conditions set forth in the Lease, as amended
hereby.

     22.  The following sections of the Basic Lease Information Sheet to the
Lease are amended to read as follows:

     Contact (Landlord):  Jeffrey Dash Telephone: 512/320-5678

     Premises:            From the Commencement Date through May 31, 1993, the
                          "Premises" is defined as that certain area containing
                          approximately 3,188 square feet of Net Rentable Area
                          of the Premises commonly known as Suite No. 230, (the
                          "Original Premises") which is located in the office
                          building, commonly referred to as San Jacinto Center
                          (the "Building") which has been constructed on the
                          land (the "Land") located on Lot 1 of San Jacinto
                          Center an addition to 

 
                          the city of Austin, Texas, according to the Plat
                          thereof recorded in Volume 89, Page 21 of the Plat
                          Records of Travis County, Texas, which Premises are
                          outlined in the plan attached hereto as Exhibit "A".
                          From June 1, 1993 through and including the day before
                          the First Additional Premises Commencement Date
                          (defined below), the "Premises" is defined as that
                          certain area containing approximately 3,337 square
                          feet of Net Rentable Area of the Premises commonly
                          known as Suite No. 430, shown as the "New Premises" in
                          the plan attached hereto as Exhibit "A-2" (the "New
                          Premises"). From and after the date (the "First
                          Additional Premises Commencement Date") that is the
                          later of (i) December 1, 1997 or (ii) the date upon
                          which the First Additional Premises Work (defined
                          below) is substantially complete, the "Premises" is
                          defined as that certain area containing approximately
                          5,811 square feet of Net Rentable Area of the Premises
                          on the 4th floor of the Building consisting of the New
                          Premises together with an adjacent additional 2,474
                          square feet of Net Rentable Area (the "First
                          Additional Premises") shown as the "First Additional
                          Premises" and the "New Premises" in the plan attached
                          hereto as Exhibit "A-2".

     Lease Term:          Lessee shall lease the Premises for the period
                          commencing on May 1, 1993 (the "Commencement Date")
                          and continuing for a period of one hundred twenty-four
                          (124) months thereafter, subject to and upon the terms
                          and conditions set forth in the Lease (as hereinafter
                          defined), or in any exhibit or addendum thereto; the
                          First Additional Premises Commencement Date shall be
                          December 1, 1997.


     Net Rentable Area    (i) From the Commencement Date until May 31, 1993, the
     of the Premises:     Net Rentable Area of the Premises is approximately
                          3,188 square feet; (ii) from June 1, 1993 through and
                          including the day before the First Additional Premises
                          Commencement Date, the Net Rentable Area of the
                          Premises is approximately 3,337 square feet; and (iii)
                          from and after the First Additional Premises
                          Commencement Date, the Net Rentable Area of the
                          Premises is approximately 5,811 square feet.

     Base Rent:           Base Rent during the Lease Term shall be: (i)
                          $2,324.58 per month, calculated at $8.75 per annum per
                          square foot of Net Rentable Area of the Original
                          Premises, from the Commencement Date until May 31,
                          1993; (ii) $2,433.23 per month, calculated at $8.75
                          per annum per square foot Of Net Rentable Area of the
                          New Premises, from June 1, 1993 through the day before
                          the First Additional Premises Commencement Date; (iii)
                          $4,237.19 per month, calculated at $8.75 per annum per
                          square foot of Net Rentable Area of the New Premises
                          and $8.75 per square foot of 

 
                          Net Rentable Area of the First Additional Premises,
                          from the First Additional Premises Commencement Date
                          through July 31, 1998; (iv) $5,558.09 per month,
                          calculated at $13.50 per annum per square foot of net
                          Rentable Area of the New Premises and $8.75 per square
                          foot of Net Rentable Area of the First Additional
                          Premises from August 1, 1998 through October 31, 2000;
                          and (v) $6,537.38 per month from and after November 1,
                          2000, calculated at $13.50 per annum per square foot
                          of Net Rentable Area of the Premises.

     Security Deposit:    (i) From the Commencement Date through and including
                          the day before the First Additional Premises
                          commencement Date, $4,232.07 and (ii) from and after
                          the First Additional Premises Commencement Date,
                          $8,747.12.

     Parking:             Subject to the terms and provisions of Rider 102
                          attached hereto and incorporated by reference herein,
                          (i) from the Commencement Date through and including
                          the day before the First Additional Premises
                          Commencement Date, two (2) reserved and three (3)
                          unreserved parking spaces shall be available to Tenant
                          and (ii) from the First Additional Premises
                          Commencement Data through the end of the Lease Term,
                          three (3) reserved and six (6) unreserved parking
                          spaces shall be available to Tenant. From the
                          Commencement Date through and including the day before
                          the First Additional Premises Commencement Date, the
                          charge for each reserved parking space shall be $80.00
                          per month plus tax and the charge for each unreserved
                          parking space shall be $60.00 per month plus tax,
                          payable to the garage operator no later than the first
                          day of each month. From and after the First Additional
                          Premises Commencement Date, the charge for each
                          reserved parking space shall be $100.00 per month plus
                          tax and the charge for each unreserved parking space
                          shall be $80.00 per month plus tax, payable to the
                          garage operator no later than the first day of each
                          month. Thereafter, the Landlord reserves the right to
                          increase or decrease the monthly rental for both the
                          reserved and unreserved parking spaces by written
                          notice to Tenant thirty (30) days in advance of any
                          change. Landlord reserves the right to terminate
                          Tenant's right to lease one (1) of the foregoing
                          reserved parking spaces upon thirty (30) days advance
                          written notice to Tenant. Tenant shall also pay any
                          taxes (other than income taxes) levied on all such
                          parking charges.

     23.  The following new section of the Basic Lease Information is hereby
added:

     Estimate of Tenant's Occupancy Costs (as defined in the Lease) from and
     after the First Additional Premises Commencement Date, based on estimated
     Occupancy Costs for 1997:

 
          $4,067.70 per month, calculated at $8.40 per annum per square foot of
          Net Rentable Area of the Premises.

     24.  Section 35(a) of the Lease is hereby amended to read in full as
follows:

          (a) All rent and other payments required to be made by Tenant to
Landlord hereunder shall be payable to the order of "Equity Office Properties"
at the address set forth below, or at such other address as Landlord may specify
from time to time by written notice delivered in accordance herewith:

          Equity office Properties
          P.O. Box 844540
          Dallas, Texas 75284-4540

     25.  Section 35(b) of the Lease is hereby amended to read in full as
follows:

          (a) Any notice or document delivered by Tenant to Landlord hereunder
shall be delivered to Landlord at the address hereinbelow set forth, or at such
other address as Landlord may specify from time to time by written notice
delivered in accordance herewith:


                         EOP-San Jacinto Limited Partnership
                         c/o Equity office Properties 160 San Jacinto Center
                         98 San Jacinto Boulevard
                         Austin, Texas 78701
                         Attn: Property Manager

        with a copy to:

                         EOP-San Jacinto Limited Partnership
                         c/o Equity Office Properties Trust
                         Two North Riverside Plaza, Suite 2200
                         Chicago, Illinois 60606
                         Attn:  General Counsel for Property Operations

     26.  Sections 54, 55 and 56 of the Lease are hereby deleted.

     27.  Section 58 of the Lease is hereby amended to read in full as follows:


     Exhibit A":        Floor Plan of the Original Premises
     Exhibit "A-2":     Floor Plan of the New Premises
     Exhibit "B":       Building Rules and Regulations
     Exhibit "C":       Acceptance of Premises Memorandum
     Exhibit "C-1":     Punch List
     Exhibit "D-1":     First Additional Premises Work Letter
     Exhibit "E-1":     Secretary of State Financing Statement
     Exhibit "E-2":     Travis County Clerk's Financing Statement
     Exhibit "F":       Subordination, Non-Disturbance and Attornment Agreement
     Exhibit "G":       Renovation Work Letter
     Exhibit "H-1":     Guaranty of Lease
     Exhibit "I":       Agreement Regarding Lender' s Security Interest

 
     Rider No. 101      Definitions Regarding Calculation of Tenant's Occupancy
                        Costs and Calculation of Net Rentable Area
     Rider No. 102      Parking

     28.  Exhibits A-I, D and H to the Lease are hereby cancelled and deleted.

     29.  Exhibits "A-2", "D-l" and "H-1" attached to this Amendment are hereby
added to the Lease.

     30.  Tenant has inspected the First Additional Premises, is familiar with
the condition of same and, subject to the completion of the First Additional
Premises Work (hereinafter defined), accepts same in its present condition.
Tenant acknowledges that Landlord previously complied with all of its
construction obligations with respect to the New Premises and that Landlord is
not obligated to do any further construction or make any additional improvements
with respect to the Premises, except that Landlord shall install or cause to be
installed in the Premises improvements (the "First Additional Premises Work")
upon the terms and conditions set forth in the Work Letter which is attached
hereto as Exhibit "D-1."  Landlord shall provide to Tenant in accordance with
the terms and conditions of such Work Letter an allowance of up to $35,729.00
calculated at $5.00 per square foot of Net Rentable Area of the First Additional
Premises and $7.00 per square foot of Net Rentable Area of the New Premises, to
be applied to the cost of the First Additional Premises Work.

     31.  Tenant represents and warrants to Landlord that it has not had any
dealing with any realtor, broker or agent in connection with this Amendment or
the negotiation thereof other than Asset Investment Corp.  Tenant agrees to
indemnify and hold Landlord harmless from and against any and all costs,
expenses or liability, including, but not limited to, reasonable attorneys'
fees, resulting from any breach of this representation or warranty.

     32.  Landlord and Tenant acknowledge that Tenant has no option or right to
renew or extend the Lease.

     33.  The Lease as amended hereby is hereby ratified and affirmed, In the
event of any conflict between the Lease and this Amendment, this Amendment shall
control.

 
     IN WITNESS WHEREOF, this Second Amendment to Office Space Lease is executed
by each party on the respective dates set forth below, but is effective as of
the date of execution by Landlord.

                              EOP-SAN JACINTO LIMITED PARTNERSHIP,
                              a Texas limited partnership

                              By:  EOP-San Jacinto GP, L.L.C.,
                                   a Delaware limited liability
                                   company, its general partner

                                 By:  EOP Operating Limited Partnership, a
                                      Delaware limited partnership, its sole
                                      member
                                    By:  Equity Office Properties Trust, a
                                         Maryland real estate investment trust,
                                         its managing general partner

                                    By:     /s/ Kim Koehn
                                            -------------------------------
                                    Name:    Kim Koehn
                                            -------------------------------
                                    Title:    Regional Vice President
                                            -------------------------------
                                Date:
                                      -------------------------------------
                              DRUG DEVELOPMENT CORP., a Texas corporation d/b/a
                              id2, Inc.

                              By:   /s/ Richard J. Hawkins
                                    --------------------------------------
                                     Name:    Richard J. Hawkins
                                             -----------------------------
                                     Title:    Chairman
                                              ----------------------------

                              id2-I, L.P., a Texas limited partnership

                              By:  Drug Development Investment Corp., a Texas
                              corporation d/b/a id2, Inc., its sole general
                              partner

                                 By:   /s/ Richard J. Hawkins
                                       -----------------------------------
                                    Name:  Richard J. Hawkins
                                           -------------------------------
                                    Title:     Chairman
                                             -----------------------------
                                Date:   October 8, 1997
                                        ----------------------------------
                                                                  "Tenant"

 
                                 EXHIBIT "H-I

                               GUARANTY OF LEASE


     WHEREAS, DRUG DEVELOPMENT INVESTMENT CORP., a Texas corporation d/b/a id2,
Inc. and id2-I, L.P., a Texas limited partnership (jointly, "Tenant") has
entered into that certain Lease Agreement dated March 17, 1993 with EOP-SAN
JACINTO LIMITED PARTNERSHIP ("Landlord"), as amended by that certain First
Amendment to office Lease dated June 1, 1993 (the "Lease") and Tenant and
Landlord are executing simultaneously with this Guaranty a Second Amendment to
the Lease; and

     WHEREAS, Landlord was not willing to enter into the Second Amendment
without the receipt of this Guaranty executed and acknowledged by the
undersigned;

     NOW, THEREFORE, to induce Landlord to execute the Second Amendment, as a
material consideration and inducement therefore (recognizing without the
execution and delivery of this Guaranty Landlord would not be willing to enter
into the Second Amendment), and recognizing the benefit of the Lease to the
undersigned, the undersigned hereby agree as follows:

     The undersigned (herein called "Guarantors" whether one or more), hereby
unconditionally, jointly and severally guarantee performance and observance by
Tenant of all the monetary obligations, duties, covenants, agreements and
conditions provided in the Lease, as same may hereafter be amended from time to
time, to be performed or observed by Tenant during the term of the Lease
(including specifically and without limiting the generality of the foregoing,
payment by Tenant of all rental and other amounts and damages of whatsoever kind
or nature which may be or become due from Tenant under the terms of or in
connection with the Lease).  This guaranty is unconditional and the liability of
Guarantors shall be absolute, in the same manner as if Guarantors, jointly and
severally, were named in and had signed the Lease as "Tenant" thereunder.
Guarantors agree that bankruptcy, insolvency, lack of corporate capacity or any
other disability or impediment against enforcement of full liability of Tenant
named in the Lease shall in no way impair or affect Guarantors' liability and
obligation hereunder, and, without limitation of the foregoing, Guarantors agree
that in the event that Tenant shall become insolvent or shall be adjudicated a
bankrupt, or shall file a petition for reorganization, arrangement or other
relief under any present or future provisions of the Bankruptcy Code, or if such
a petition be filed by creditors of Tenant, or if Tenant shall seek a judicial
readjustment of the rights of its creditors under any present or future federal
or state law or if a receiver of all or part of Tenant's property and assets is
appointed by any state or federal court, no such proceeding or action taken
therein shall modify, diminish or in any way affect the liability of Guarantors
under this guaranty, and the liability of Guarantors for the Tenant's monetary
obligations under the Lease shall be of the same scope as if Guarantors had
themselves, jointly and severally, executed the Lease, and no "rejection" and/or
"termination" of the Lease in any of the proceedings referred to above shall be
effective to limit, release and/or terminate the continuing liability of
Guarantors to Landlord under this guaranty with respect to the Lease and such
liability of Guarantors shall be unaffected by any such "rejection" and/or
"termination" in said proceedings.  It shall not be necessary or required in
order to maintain and enforce Guarantors' liability hereunder that demand be
made upon Tenant or that action be commenced 

 
or prosecuted against Tenant or that any effort be made to enforce the liability
or responsibility of Tenant for performance of its obligations or duties under
or in connection with the Lease, and it shall not be required that Tenant or any
other party liable on such Lease be joined in any action brought against
Guarantors for enforcement of Guarantors' liability and responsibility under
this guaranty or that judgment have theretofore been obtained against Tenant or
any other party liable therefor on or in connection with any such claim.
Guarantors agree that no waiver by Landlord or forbearance or delay by Landlord
in asserting or enforcing any rights or remedies of Landlord against or with
respect to Tenant or any other party who may be or becomes responsible for
performance of any of such Tenant's obligations or duties shall in any way
affect, impair or release Guarantors' liability hereunder. Likewise, Guarantors
agree that no assignment or subletting of the Lease or of all or any part of the
leased premises by such Tenant shall in any way impair, affect or release
Guarantors' liability hereunder. Guarantors expressly waive and agree that no
notice of default by Tenant or other notice or demand need be given by Landlord
to Guarantors as a condition of maintaining or enforcing Guarantors' liability
and obligations under this guaranty. Guarantors expressly agree that no notice
of amendment or modification of the Lease need be given by Landlord or Tenant to
Guarantors as a condition of maintaining or enforcing Guarantors' liability and
obligations under this guaranty. Guarantors expressly agree that any amendment
or modification of the Lease may be made by Landlord and Tenant, as provided in
such Lease, with or without the approval of Guarantors, and that any such
amendment will be deemed part of the Lease for purposes of this guaranty.
Likewise, Guarantors agree that Landlord's release or subordination or failure
or delay to enforce or seek to realize upon any security now or hereafter held
or acquired by Landlord for performance of any of the obligations or duties of
Tenant under or in connection with the Lease shall in no way impair, affect or
release Guarantors' liability hereunder, and that Landlord's action (at
Landlord's election) in terminating such Lease or in taking or retaking
possession of the leased premises as therein provided following default by
Tenant shall not release or impair Guarantors' liability hereunder and that no
notice of such termination or of such entry or re-entry by Landlord need be
given to Guarantors. Without limitation of anything herein to the contrary,
Guarantors agree that any waiver by Lessor or forbearance or failure or delay by
Lessor in asserting or enforcing its rights against any of the undersigned under
this guaranty shall in no way affect, impair or release the liability of any of
the other Guarantors hereunder.

     NOTWITHSTANDING ANYTHING HEREIN TO THE CONTRARY, THE MAXIMUM LIABILITY OF
GUARANTORS HEREUNDER SHALL BE LIMITED TO $66,592.89, PLUS ALL COSTS, INCLUDING
WITHOUT LIMITATION, REASONABLE ATTORNEYS' FEES, INCURRED IN ENFORCING THIS
GUARANTY (THE "GUARANTEED AMOUNT").  THE GUARANTEED AMOUNT SHALL BE REDUCED BY
AN AMOUNT EQUAL TO ONE MONTH'S BASE RENT FOR EACH FULL MONTH OF THE LEASE TERM
IN WHICH TENANT PERFORMS ALL OF ITS MONETARY OBLIGATIONS UNDER THE LEASE.
LANDLORD AGREES THAT IT WILL RELEASE THIS GUARANTY OF LEASE UPON SATISFACTION OF
THE FOLLOWING CONDITIONS: (I) LANDLORD RECEIVES AUDITED FINANCIAL STATEMENTS
SHOWING THAT SENSUS DRUG DEVELOPMENT CORP. HAS A NET WORTH OF AT LEAST
$10,000,000.00 AND (II) SENSUS DRUG DEVELOPMENT CORP. SIGNS A NEW GUARANTY OF
LEASE IN SUBSTANTIALLY THE SAME FORM AS THIS GUARANTY OF LEASE.

 
     This guaranty shall be enforceable and shall be performed in Travis County,
Texas.

     WITNESS the execution hereof effective as of the date of execution and
delivery of the Second Amendment.


Address:                                        /s/ Rick Hawkins
                                        -----------------------------------
                                        Name: Rick Hawkins


98 San Jacinto Boulevard
Austin, Texas  78701

 

 
                                THIRD AMENDMENT

     This Third Amendment (the "Amendment") is made and entered into as of the
7th day of August, 1998, by and between EOP-SAN JACINTO LIMITED PARTNERSHIP, a
Texas limited partnership ("Landlord"), and SENSUS DRUG DEVELOPMENT CORPORATION,
a Delaware corporation ("Tenant").

                              W I T N E S S E T H

A.   WHEREAS, Landlord (formerly know as San Jacinto Tower Limited Partnership,
     a Texas limited partnership) and Tenant (as successor in interest to Drug
     Development Investment Corp., a Texas corporation, d/b/a id2, Inc. and id2-
     I, L.P., a Texas limited partnership) are parties to that certain lease
     dated the 17th day of March, 1993, for space currently containing
     approximately 5,811 square feet of Net Rentable Area (the "Original
     Premises") described as Suite No. 430 on the fourth (4th) floor of the
     building commonly known as San Jacinto Center and the address of which is
     98 San Jacinto Blvd., Austin, Texas (the "Building"), which lease has been
     previously amended by Acceptance of Premises memorandum dated August 23,
     1993, First Amendment to Office Lease dated June 1, 1993, Second Amendment
     to Office Space Lease dated November 5, 1997 and Commencement Letter dated
     February 20, 1998 (collectively, the "Lease"); and

B.   WHEREAS, Tenant has requested that additional space containing
     approximately 5,298 square feet of Net Rentable Area described as Suite No.
     200 on the second (2nd) floor of the Building shown on Exhibit A hereto
     (the "Expansion Space") be added to the Original Premises and that the
     Lease be appropriately amended and Landlord is willing to do the same on
     the terms and conditions hereinafter set forth;

C.   WHEREAS, Tenant desires to document that the lease has previously been
     assigned from Drug Development Investment Corp., a Texas corporation, d/b/a
     id2, Inc., and id2-I, L.P., a Texas limited partnership ("Assignor") and
     Landlord's consent to said assignment;

     NOW, THEREFORE, in consideration of the mutual covenants and agreements
     herein contained and other good and valuable consideration, the receipt and
     sufficiency of which are hereby acknowledged, Landlord and Tenant agree as
     follows:

          I.   ASSIGNMENT.  Assignor hereby transfers and assigns to Tenant all
of Assignor's right, title and interest in the Lease.  Tenant hereby accepts the
assignment granted herein and assumes and agrees to make all payments and to
perform all other obligations of tenant under the Lease.  Landlord hereby
consents to such assignment, provided that nothing herein shall be construed as
to release Assignor from any obligations under the Lease.

          II.  EXPANSION AND EFFECTIVE DATE.  Effective as of September 1, 1998
(the "Expansion Effective Date"), the Premises, as defined in the Lease, is
increased from 5,811 square feet of Net Rentable Area on the fourth (4th) floor
to 11,109 square feet of Net Rentable Area on the second (2nd) and fourth (4th)
floors by the addition of the Expansion Space, and from and after the Expansion
Effective Date, the Original Premises and the Expansion Space, collectively,
shall be deemed the Premises, as defined in the Lease.  The Lease Term for the

 
Expansion Space shall commence on the Expansion Effective Date and on August 31,
2003 (the "Termination Date").  The Expansion Space is subject to all the terms
and conditions of the Lease except as expressly modified herein and except that
Tenant shall not be entitled to receive any allowances, abatements or other
financial concessions granted with respect to the Original Premises unless such
concessions are expressly provided for herein with respect to the Expansion
Space.

          III. BASE RENT

          In addition to Tenant's obligation to pay Base Rent for the Original
          Premises, Tenant shall pay Landlord the sum of Four Hundred Twenty-
          Three Thousand Eight Hundred Forty and NO/100 Dollars ($423,840.00) as
          Base Rent for the Expansion Space in sixty (60) monthly installments
          as follows:

               A.  Sixty (60) equal installments of Seven Thousand Sixty-Four
and NO/100 Dollars ($7,064.00) each payable on or before the first day of each
month during the period beginning September 1, 1998 and ending August 31, 2003.

          All such Base Rent shall be payable by Tenant in accordance with the
          terms of the Lease.

          IV.  ADDITIONAL SECURITY DEPOSIT.  Upon Tenant's execution hereof,
Tenant shall pay Landlord the sum of Eleven Thousand and NO/100 Dollars
($11,000.00) which is added to and becomes part of the Security Deposit held by
Landlord as provided under the Lease as security for payment of rent and the
performance of the other terms and conditions of the Lease by Tenant.
Accordingly, simultaneous with the execution hereof, the Security Deposit is
increased from $8,747.12 to $19,747.12.  Notwithstanding anything stated herein
to the contrary, provided Tenant is not in default under the Lease as of the
effective date of any reduction of the Security Deposit or as of the date
Landlord is required to return such portion of the Security Deposit, Tenant
shall have the right to reduce the amount of the Security Deposit to $8,747.12
effective as of the last day of the twenty-fourth (24th) full calendar month
following the Expansion Effective Date.  If Tenant is entitled to a reduction in
the Security Deposit, Tenant shall have the right to provide Landlord with
written notice requesting that the Security Deposit be reduced as provided above
(the "Reduction Notice").  If Tenant provides Landlord with a Reduction Notice,
Landlord shall refund the applicable portion of the Security Deposit to Tenant
within forty-five (45) days after the later to occur of (i) Landlord's receipt
of the Reduction Notice, or (ii) the date upon which Tenant is entitled to a
reduction in the Security Deposit as provided above.

          V.   TENANT'S PROPORTIONATE SHARE OF OPERATING COSTS.  For the period
commencing with the Expansion Effective Date and ending on the Termination Date,
Tenant's Proportionate Share of Operating Costs for the Expansion Space is one
and three thousand five hundred twenty-four ten-thousandths percent (1.3524%).

          VI.  OPERATING COSTS.  For the period commencing with the Expansion
Effective Date and ending on the Termination Date, Tenant shall pay for its
Proportionate Share of Operating Costs applicable to the Expansion Space in
accordance with the terms of the Lease.

 
          VII. IMPROVEMENTS TO EXPANSION SPACE.

               A.  Condition of Expansion Space. Tenant has inspected the
Expansion Space and agrees to accept the same "as is" without any agreements,
representations, understandings or obligations on the part of Landlord to
perform any alterations, repairs or improvements, except as may be expressly
provided otherwise in this Amendment.

               B.  Cost of Improvements to Expansion Space. Provided Tenant is
not in default, Tenant shall be entitled to receive an improvement allowance
(the "Expansion Improvement Allowance") in an amount not to exceed Thirty-Nine
Thousand Seven Hundred Thirty-Five and NO/100 Dollars ($39,735.00) (i.e., $7.50
per square foot of Net Rentable Area of the Expansion Space) to be applied
toward the cost of performing initial construction, alteration or improvement of
the Expansion Space, including but not limited to the cost of space planning,
design and related architectural and engineering services. In the event the
total cost of the initial improvements to the Expansion space exceeds the
Expansion Improvement Allowance, Tenant shall pay for such excess upon demand.
The entire unused balance of the Expansion Improvement Allowance, if any, shall
accrue to the sole benefit of Landlord. Landlord shall pay such Expansion
Improvement Allowance directly to the contractors retained to perform the
construction, design or related improvement work to the Expansion Space.

               C.  Responsibility for improvements to Expansion Space.  Any
construction, alterations or improvements to the Premises shall be performed by
Tenant using contractors selected by Tenant and approved by Landlord, which
approval shall not be unreasonable withheld or delayed, and shall be governed in
all respects by the provisions of Article 13, "Alterations and Additions by
Tenant," of the Lease.

          VIII. EARLY ACCESS TO EXPANSION SPACE.  During any period that Tenant
shall be permitted to enter the Expansion Space prior to the Expansion Effective
Date (e.g., to perform alterations or improvements, if any).  Tenant shall
comply with all terms and provisions of the Lease, except those provisions
requiring payment of Base Rent or Additional Rent as to the Expansion Space.  If
Tenant takes possession of the Expansion Space prior to the Expansion Effective
Date for any reason whatsoever (other than the performance of work in the
Expansion Space with Landlord's prior approval), such possession shall be
subject to all the terms and conditions of the Lease and this Amendment, and
Tenant shall pay Base Rent and Additional Rent as applicable to the Expansion
Space to Landlord on a per diem basis for each day of occupancy prior to the
Expansion Effective Date.

          IX.  OTHER PERTINENT PROVISIONS.  Landlord and Tenant agree that,
effective as of the date hereof (unless different effective date(s) is/are
specifically referenced in this Section), the Lease shall be amended in the
following additional respects:

               A.  PARKING.  Subject to the terms and conditions set forth in
Rider No. 102, "Parking" of the Lease, effective as of the Expansion Effective
Date, Landlord hereby agrees to make available to Tenant and Tenant hereby
agrees to pay for and take, during the balance of the Lease Term, six (6)
unreserved parking spaces (the "Additional Unreserved Space(s)") and two (2)
reserved parking spaces (the "Additional Reserved Space(s)") for automobiles in
the Building's parking garage. Tenant shall pay Landlord the sum of One

 
Hundred and NO/100 Dollars ($100.00) per Additional Unreserved Space per month
plus applicable taxes and the sum of One Hundred Seventy-Five and NO/100 Dollars
($175.00) per Additional Reserved Space per month plus applicable taxes (the
parking charges for the Additional Unreserved Spaces and the Additional Reserved
Spaces are hereinafter collectively referred to as "Parking Rent"). Landlord
shall have the right to increases the Parking Rent from time to time to reflect
the rate then being charged by Landlord for parking spaces in the Building's
parking garage.

               B.  FINANCIAL STATEMENTS.  Notwithstanding anything contained in
the Lease to the contrary, at any time during the Lease Term, Tenant shall
provide Landlord, upon ten (10) days' prior written notice from Landlord, with a
current financial statement showing, at a minimum, Tenant's then current net
worth. Such statement shall be prepared in accordance with generally accepted
accounting principles and, if such is the normal practice of Tenant, shall be
audited by an independent certified public accountant.

          X.   MISCELLANEOUS.

               A.  This Amendment sets forth the entire agreement between the
parties with respect to the matters set forth herein. There have been no
additional oral or written representations or agreements. Under no circumstances
shall Tenant be entitled to any Rent abatement, improvement allowance, leasehold
improvements, or other work to the Premises, or any similar economic incentives
that may have been provided Tenant in connection with entering into the Lease,
unless specifically set forth in this Amendment.

               B.  Except as herein modified or amended, the provisions,
conditions and terms of the Lease shall remain unchanged and in full force and
effect.

               C.  In the case of any inconsistency between the provisions of
the Lease and this Amendment, the provisions of this Amendment shall govern and
control.

               D.  Submission of this Amendment by Landlord is not an offer to
enter into this Amendment but rather is a solicitation for such an offer by
Tenant. Landlord shall not be bound by this Amendment until Landlord has
executed and delivered the same to Tenant.

               E.  The capitalized terms used in this Amendment shall have the
same definition as set forth in the Lease to the extent that such capitalized
terms are defined therein and not redefined in this Amendment.

               F.  Tenant hereby represents to landlord that Tenant has dealt
with no broker other than Asset Investment Corp., in connection with this
Amendment. Tenant agrees to indemnify and hold Landlord, its members,
principals, beneficiaries, partners, officers, directors, employees,
mortgagee(s) and agents, and the respective principals and members of any such
agents (collectively, the "Landlord Related Parties") harmless from all claims
of any brokers other than Asset Investment Corp., claiming to have represented
Tenant in connection with this Amendment. Landlord hereby represents to Tenant
that Landlord has dealt with no broker in connection with this Amendment.
Landlord agrees to indemnify and hold Tenant, it members, principals,
beneficiaries, partners, officers, directors, employees, and agents, and the
respective principals and members of any such agents (collectively, the "Tenant
Related Parties") harmless 

 
from all claims of any brokers claiming to have represented Landlord in
connection with this Amendment.

               G.  This Amendment shall be of no force and effect unless and
until accepted by any guarantors of the Lease, who by signing below shall agree
that their guarantee, as restated, shall apply to the Lease as amended herein.

 
     IN WITNESS WHEREOF, Landlord and Tenant have duly executed this Amendment
as of the day and year first above written.

WITNESSES ATTESTATION                   LANDLORD:  EOP-SAN JACINTO LIMITED
                                        PARTNERSHIP, a Texas limited partnership

/s/ Deidre A. Hopkins
- --------------------------------

Name (print): Deidre A. Hopkins         By:  EOP-SAN JACINTO GP, L.L.C., a 
             -------------------             Delaware limited liability 
                                             company, its general partner

                                        By:  EOP OPERATING LIMITED PARTNERSHIP,
- --------------------------------             a Delaware limited partnership, its
                                             sole member

Name (print):                           By:  Equity Office Properties Trust, a
             -------------------             Maryland real estate investment
                                             trust, its managing general partner

                                             By: /s/ Brad Fricks
                                                --------------------------------
                                             Name:  Brad Fricks
                                             Title: Vice President  Leasing

                                        TENANT:  SENSUS DRUG DEVELOPMENT
                                        CORPORATION, a Delaware corporation

                                        By:  /s/ Robert J. Davis
                                           -------------------------------------
                                            Name:  Robert J. Davis
                                            Title: Executive Vice President

                                           /s/ Richard J. Hawkins
                                        ----------------------------------------
                                        Name:  Richard J. Hawkins

 
                          RESTATED GUARANTY OF LEASE

     WHEREAS, Landlord (formerly known as San Jacinto Tower Limited Partnership,
a Texas limited partnership) and Tenant (as successor in interest to Drug
Development Investment Corp., a Texas corporation, d/b/a Id/2/, Inc. and Id/2/-
I, L.P., a Texas limited partnership) are parties to that certain Lease dated
the 17th day of March, 1993, for space currently containing approximately 5,811
square feet of Net Rentable Area (the "Original Premises") described as Suite
No. 430 on the fourth (4/th/) floor of the building commonly known as San
Jacinto Center and the address of which is 98 San Jacinto Blvd, Austin, Texas
(the "Building"), which lease has been previously amended by Acceptance of
Premises Memorandum dated August 23, 1993, First Amendment to Office Lease dated
June 1, 1993. Second Amendment to Office Space Lease dated November 5, 1997 and
Commencement Letter dated February 20, 1998 (collectively, the "Lease") and
Tenant and Landlord are executing simultaneously with this Guaranty a Third
Amendment to the Lease; and

     WHEREAS, Richard J. Hawkins (herein called "Guarantors" whether one or
more) has executed that certain unconditional guaranty of Lease dated November
5, 1997 (the "Guaranty") as an inducement to Landlord to lease the Premises to
Tenant; and

     WHEREAS, Lessor and Lessee desire to restate the Guaranty (the "Restated
Guaranty");

     NOW, THEREFORE, to induce Landlord to execute the Third Amendment, as a
material consideration and inducement therefore (recognizing without the
execution and delivery of this Restated Guaranty Landlord would not be willing
to enter into the Third Amendment), and recognizing the benefit of the Lessee to
the undersigned, the undersigned hereby agree as follows:

     The undersigned (herein called "Guarantors" whether one or more), hereby
unconditionally, jointly and severally guarantee performance and observance by
Tenant of all the monetary obligations, duties, covenants, agreements and
conditions provided in the Lease, as same may hereafter be amended from time to
time, to be performed or observed by Tenant during the term of the Lease
(including specifically and without limiting the generality of the foregoing,
payment by Tenant of all rental and other amounts and damages of whatsoever kind
or nature which may be or become due from Tenant under the terms of or in
connection with the Lease).  This guaranty is unconditional and the liability of
Guarantors shall be absolute, in the same manner as if Guarantors, jointly and
severally, were named in and had signed the Lease as "Tenant" thereunder.
Guarantors agree that bankruptcy, insolvency, lack of corporate capacity or any
other disability or impediment against enforcement of full liability of Tenant
named in the Lease shall in no way impact or affect Guarantors' liability and
obligation hereunder, and, without limitation of the foregoing.  Guarantors
agree that in the event that Tenant shall become insolvent or shall be
adjudicated a bankrupt, or shall file a petition for reorganization, arrangement
or other relief under any present or future provisions of the Bankruptcy Code,
or if such a petition be filed by creditors of Tenant, or if Tenant shall seek a
judicial readjustment of the rights of its creditors under any present or future
federal or state law or if a receiver of all or part of Tenant's property and
assets is appointed by any state or federal court, no such 

 
proceeding or action taken therein shall modify, diminish or in any way affect
the liability of Guarantors under this Guaranty, and the liability of Guarantors
for the Tenant's monetary obligations under the Lease shall be of the same scope
as if Guarantors had themselves, jointly and severally, executed the Lease, and
no "rejection" and/or "termination" of the Lease in any of the proceedings
referred to above shall be effective to limit, release and/or terminate the
continuing liability of Guarantors to Landlord under this guaranty with respect
to the Lease and such liability of Guarantors shall be unaffected by any such
"rejection" and/or "termination" in said proceedings, it shall not be necessary
or required in order to maintain and enforce Guarantors' liability hereunder
that demand be made upon Tenant or that action be commenced or prosecuted
against Tenant or that any effort be made to enforce the liability or
responsibility of Tenant for performance of its obligations or duties under or
in connection with the Lease, and it shall not be required that Tenant or any
other party liable on such lease be joined in any action brought against
Guarantors for enforcement of Guarantors' liability and responsibility under
this guaranty or that judgment have theretofore been obtained against Tenant or
any other party liable therefor on or in connection with any such claim.
Guarantors agree that no waiver by Landlord or forbearance or delay by Landlord
in asserting or enforcing any rights or remedies of Landlord against or with
respect to Tenant or any other party who may be or becomes responsible for
performance of any of such Tenant's obligations or duties shall in any way
affect, impair or release Guarantors' liability hereunder. Likewise, Guarantors
agree that no assignment or subletting of the Lease or of all or any part of the
leased premises by such Tenant shall in any way impair, affect or release
Guarantors' liability hereunder. Guarantors expressly waive and agree that no
notice of default by Tenant or other notice or demand need be given by Landlord
to Guarantors as a condition of maintaining or enforcing Guarantors' liability
and obligations under this guaranty. Guarantors expressly agree that no notice
of amendment or modification of the Lease need be given by Landlord or Tenant to
Guarantors as a condition of maintaining or enforcing Guarantors' liability and
obligations under this guaranty. Guarantors expressly agree that any amendment
or modification of the Lease may be made by Landlord and Tenant, as provided in
such Lease, with or without the approval of Guarantors, and that any such
amendment will be deemed part of the Lease for purposes of this guaranty.
Likewise, Guarantors agree that Landlord's release or subordination or failure
or delay to enforce or seek to realize upon any security now or hereafter held
or acquired by Landlord for performance of any of the obligations or duties of
Tenant under or in connection with the Lease shall in no way impair, affect or
release Guarantors' liability hereunder, and that Landlord's action (at
Landlord's election) in terminating such Lease or in taking or retaking
possession of the leased premises as therein provided following default by
Tenant shall not release or impair Guarantors' liability hereunder and that no
notice of such termination or of such entry or re-entry by landlord need be
given to Guarantors. Without limitation of anything herein to the contrary,
Guarantors agree that any waiver by Lessor or forbearance or failure or delay by
Lessor in asserting or enforcing its rights against any of the undersigned under
this guaranty shall in no way affect, impair or release the liability of any of
the other Guarantors hereunder.

     NOTWITHSTANDING ANYTHING HEREIN TO THE CONTRARY, THE MAXIMUM LIABILITY OF
GUARANTOR HEREUNDER SHALL BE LIMITED TO $112,695.37, PLUS ALL COSTS, INCLUDING
WITHOUT LIMITATION, REASONABLE ATTORNEYS' FEES, INCURRED IN ENFORCING THIS
GUARANTY (THE "GUARANTEED AMOUNT").  THE GUARANTEED AMOUNT SHALL BE REDUCED BY
AN AMOUNT EQUAL TO ONE MONTH'S BASE RENT FOR EACH 

 
FULL MONTH OF THE LEASE TERM, OR ANY EXTENSION THEEOF, IN WHICH TENANT PERFORMS
ALL OF ITS MONETARY OBLIGATIONS UNDER THE LEASE. LANDLORD AGREES THAT IT WILL
RELEASE THIS GUARANTY OF LEASE IF AT ANY TIME DURING THE LEASE TERM LANDLORD
RECEIVES AUDITED FINANCIAL STATEMENTS SHOWING THAT SENSUS DRUG DEVELOPMENT
CORPORATION, A DELAWARE CORPORATION HAS A NET WORTH OF AT LEAST $10,000,000.00,
PROVIDED THAT THIS GUARANTY SHALL BE REINSTATED IF AT ANY TIME THEREAFTER SENSUS
DRUG DEVELOPMENT CORPORATION'S NET WORTH FALLS BELOW $10,000,000.00 AND IN SUCH
EVENT THE UNDERSIGNED GUARANTOR AGREES TO EXECUTE A NEW GUARANTY OF LEASE IN
SUBSTANTIALLY THE SAME FORM AS THIS GUARANTY OF LEASE, PROVIDED FURTHER THAT
SUCH REINSTATED GUARANTY OF LEASE SHALL BE IN AN AMOUNT REDUCED AS APPLICABLE IN
ACCORDANCE WITH THE FOREGOING PROVISION.

     This guaranty shall be enforceable and shall be performed in Travis County,
Texas.

     WITNESS the execution hereof effective as of the date of execution and
delivery of the Second Amendment.

ADDRESS:                            /s/ Richard J. Hawkins
                                    ------------------------------------
                                    Name:  Richard J. Hawkins

98 San Jacinto Blvd. #430
- -------------------------
Austin, TX  78701
- -------------------------