EXHIBIT 10.13

                  AMENDED ASSIGNMENT AND ASSUMPTION AGREEMENT
                  -------------------------------------------

                                        

     1.   OHIO UNIVERSITY, a state chartered university and its EDISON ANIMAL
BIOTECHNOLOGY CENTER, a department of Ohio University, located at 101 University
Research and Technology Center, Athens, Ohio 45701 and DRUG DEVELOPMENT
INVESTMENT CORP., a Texas corporation doing business as id/2/, Inc. and having
a principal place of business at 570 Penllyn Pike, Blue Bell, Pennsylvania 19422
("DDIC"), entered into that (i) certain Biotechnology Licensing and Transfer
Agreement relating to growth hormone and gh antagonist technology (the "License
Agreement) and (ii) that certain Sponsored Research Agreement (the "Research
Agreement"), both dated effective as of January 18, 1993 (collectively, the
"Contracts").

     2.   Section 22 of the License Agreement and Section 11.1 of the Research
Agreement permit DDIC to assign the respective Contracts, in whole or in part,
to any of its Affiliates, and in such event the Contracts shall become
automatically binding upon the assignee. DDIC's Affiliates, as defined under
section 1(a) of the License Agreement and Section 11.1 of the Research
Agreement, include id/2/-I, L.P., a Texas limited partnership maintaining
offices in Austin, Texas and at 570 Penllyn Pike, Blue Bell, Pennsylvania 19422
("id/2/-I, L.P."). DDIC is the Managing (and sole) General Partner of id/2/-I,
L.P. and directs its management and business affairs. DDIC and id/2/-I, L.P. are
the "parties" herein.

     3.   DDIC hereby assigns and transfers to id/2/-I, L.P., and in
consideration thereof id/2/-I, L.P. hereby (a) accepts and assumes, all of
DDIC's rights, duties, and obligations hereafter arising under the Contracts and
(b) conveys to DDIC a one percent interest as a general partner in the equity
and capital, income and distributions, losses, deductions, and credits of 
id/2/-I, L.P. The parties agree that all rights, obligations and protections
running in DDIC's favor under the Contracts shall now run in favor of - and be
binding upon -id/2/-I, L.P.

     4.   The parties agree that DDIC is not hereby released from its duties and
responsibilities under the Contracts, and that DDIC shall be indemnified and
held harmless by id/2/-I, L.P. for all of its costs, losses, damages and
expenses, including attorney's fees, hereafter incurred or suffered by DDIC as a
result of any failure of id/2/-I, L.P. to properly perform its duties and pay
its obligations under the Contracts.

                                      1.

 
     5.   Except as modified herein, the terms and provisions of the Contracts
are hereby ratified and reaffirmed by the parties.

     6.   Any previous involvement of id/2/-I, L.P. in the performance of DDIC's
duties and responsibilities under the Contracts is hereby ratified and approved,
without waiving any substantive rights that the parties may have with respect to
such performance under the Contracts.

     EXECUTED in multiple original counterparts with an effective date as of
March 26, 1993.

                                      DRUG DEVELOPMENT INVESTMENT CORP.
                                            
                                            
                                      By: /s/ Richard J. Hawkins
                                         _______________________________________
                                         Richard J. Hawkins, Chairman
                                            
                                            
                                      id/2/-I, L.P., a Texas Limited Partnership
                                            
                                      By:  DRUG DEVELOPMENT INVESTMENT CORP.
                                           Its Managing General Partner
                                            
                                            
                                      By: /s/ Richard J. Hawkins
                                         _______________________________________
                                         Richard J. Hawkins, Chairman
                                            

                                      2.