ASSIGNMENT FOR SECURITY

                                  (TRADEMARKS)

STATE OF GEORGIA  )

                  )  SS.:

COUNTY OF FULTON  )

                  WHEREAS, PRINCETON DIAGNOSTIC LABORATORIES OF AMERICA, INC., a
Delaware  corporation  (the  "Assignor"),  has adopted,  used and is using marks
which are either  registered  or applied  for in the  United  States  Patent and
Trademark Office as set forth on Exhibit A (the "Trademarks"), and

                  WHEREAS,  the Assignor is the sole owner of the entire  right,
title  and  interest  in and to the  Trademarks  which  are  registered  and the
goodwill of the business  symbolized  by the  Trademarks  and the  registrations
thereof, and

                  WHEREAS, Assignor has entered into that certain Guaranty dated
of even date (as  amended,  supplemented  or  restated  from  time to time,  the
"Guaranty")  in  favor  of  HELLER  FINANCIAL,   INC.,  a  Delaware  corporation
("Lender"), and

                  WHEREAS,  as a condition  precedent  to the  extension  of the
financial  accommodations  to or for the  benefit of certain  affiliates  of the
Assignor  pursuant  to the Loan  Agreement  (as  defined in the  Guaranty),  the
Assignor  has  agreed to assign  to Lender  and to grant to Lender a  continuing
security  interest in, and a continuing  lien on, all of the  Assignor's  right,
title  and  interest  in and  to  the  following  (collectively  the  "Trademark
Collateral"),

                  (a) the  Trademarks,  together  with all rights,  benefits and
         privileges  derived  therefrom,   and  the  goodwill  of  the  business
         symbolized by the Trademarks and the registrations thereof, and

                  (b) all proceeds thereof,  including,  but not limited to, any
         claims and demands  arising out of any  infringement of the Trademarks,
         including  the right to settle  disputes  concerning  such  claims  and
         demands.

                  NOW,  THEREFORE,  in order to induce Lender to consummate  the
financial  accommodations  to certain  affiliates of the Assignor as provided in
the Loan Agreement,  and for other good and valuable consideration,  receipt and
sufficiency of which are hereby acknowledged, the Assignor does hereby assign to
Lender and grant to Lender a  continuing  security  interest in and a continuing
lien on,  the  entire  right,  title  and  interest  of  Assignor  in and to the
Trademark  Collateral.  The  Trademark  Collateral  shall  serve  as  collateral
security to Lender for the payment 



and  performance  of the  obligations  of the Assignor  under  the  Guaranty  
and  for  the  payment  and  performance  of the Obligations (as such term is 
defined in the Loan Agreement) and shall constitute a part of the  Collateral 
(as such term is defined in the Loan  Agreement),  and shall be subject to all 
of the terms and conditions of the Loan Agreement, which is incorporated 
herein by reference.

                  Unless and until said lien and security interest is foreclosed
upon,  Assignor  (i) shall be deemed to  remain  in  exclusive  and  undisturbed
possession  of the  Trademarks,  (ii)  shall  exclusively  retain  all rights to
license others under the  Trademarks,  but only in a manner  consistent with the
preservation of their current substance, validity, registration and the security
interest  granted herein,  and (iii) may bring suit for the  infringement of the
Trademarks  and to retain the  proceeds  of the  foregoing.  Lender  need not be
joined as a plaintiff in any such infringement suit; provided, that should it be
necessary,  in Lender's sole judgment, that Lender be joined as an indispensable
party or true party in interest in any such infringement  suit, Lender shall, at
its option, either

                  (1) appoint  Assignor  its attorney in fact for the purpose of
         prosecuting  such  infringement  suit  on the  express  condition  that
         Assignor  indemnify and hold Lender harmless for any liability incurred
         by Lender as a result of such appointment, or

                  (2) participate actively in the prosecution of such suit.

                  Assignor  further  agrees  (i)  that  while  a  secured  party
hereunder,  Lender  shall have no  obligation  or  responsibility  to protect or
defend the Trademark  Collateral and Assignor shall at its own expense  protect,
defend  and  maintain  the  same  to the  extent  reasonably  advisable  for its
business, (ii) to use its best efforts to detect any infringers of the Trademark
Collateral, to forthwith advise Lender in writing of infringements detected, and
protect, defend and maintain the Trademark Collateral against any infringements,
(iii) that if Assignor fails to comply with the foregoing  clauses (i) and (ii),
Lender  may do so in  Assignor's  name or in  Lender's  name  but at  Assignor's
expense,  and  Assignor  hereby  agrees to  reimburse  Lender for all  expenses,
including  reasonable   attorneys'  fees,  incurred  by  Lender  in  protecting,
defending and maintaining the Trademark  Collateral owned by Assignor,  and (iv)
to use the Trademarks only in its businesses as they are presently conducted.

                  The  security  interest in the  Trademark  Collateral  granted
hereunder  shall  remain  in full  force  and  effect  until  the  later  of the
termination  of the Loan Agreement and the payment and  satisfaction  in full of
the Obligations  and the obligations of the Assignor under the Guaranty.  At any
time thereafter  Lender shall, if requested by Assignor,  execute and deliver to
Assignor, or to a third party upon Assignor's instructions,  for filing with the
United  States  Patent  and  Trademark  Office  and in each  office in which any
financing  statement  relative to the security  interest granted hereby may have
been filed,  (i)  documentation  in accordance with the rules and regulations of
said office,  (ii) termination  statements under the Uniform Commercial Code and
(iii) any other documentation  reasonably  requested by Assignor,  all as may be
necessary to release Lender's interest in the Trademark  Collateral,  and all at
the cost and expense of Assignor.

                                  -2-



                  IN WITNESS WHEREOF, the Assignor has caused this Assignment to
be duly executed by its authorized officer or agent as of January ___, 1996.

                                                  PRINCETON DIAGNOSTIC 
                                                  LABORATORIES OF AMERICA, INC.

                                                  By:

                                                  Title:

                                                  Attest:

                                                  Title:

                                                       [CORPORATE SEAL]



STATE OF GEORGIA  )

                  )  ss.:

COUNTY OF FULTON  )

                  On this ___ day of January,  1996,  before me personally  came
___________________  and  _____________________,  to me known,  who, being by me
duly   sworn,   did   depose   and  say  that   they  are,   respectively,   the
____________________and    _____________________    of   PRINCETON    DIAGNOSTIC
LABORATORIES  OF  AMERICA,  INC.,  the  corporation  described  herein and which
executed the foregoing instrument;  that they know the seal of said corporation;
that the seal affixed to said  instrument is such corporate seal; that it was so
affixed by order of the Board of  Directors  of said  corporation  and that they
signed thereto by like order.

                                               Sworn to and subscribed before me
                                               me this ___ day of January, 1996.

                                               Notary Public

                           -3-



                                                       [NOTARIAL SEAL]

                                               My Commission Expires:

                           -4-




                                    EXHIBIT A

     TRADEMARK        REGISTRATION NUMBER       REGISTRATION DATE

PDLA                       1,477,191                 02/16/88