EXHIBIT 4.10

                      Joint Venture Shareholders' Agreement

                                November 14, 1995

Between: York Medical Inc.("YM"), a company incorporated under the laws of the
Province of Ontario, Canada, CIMYM Inc., a company incorporated under the laws
of the Province of Ontario, Canada ("CIMYM") and CIMAB S.A. ("CIMAB") a Cuban
company incorporated under the laws of the Republic of Cuba, representing Centro
de Inmunologia Molecular ("CIM").

                                    RECITALS

    Whereas:

o     CIMAB  entered into a licencing  agreement on behalf of CIM,  dated May 3,
      1995 (the "Licencing Agreement");

o     CIMYM has been incorporated to serve as a joint venture company,  owned as
      to 80% of its  common  equity by YM and as to 20% by CIMAB,  to market the
      licenced  products  assigned  to  it  by  YM  pursuant  to  the  Licencing
      Agreement;

o     Certain of the benefits and obligations of the Licence Agreement have been
      assigned to CIMYM by YM; and

o     The purpose of this agreement is to set out the  relationship  between the
      parties hereto so that they will proceed on a mutually beneficial basis.

Now, therefore, for good and valuable consideration and the sum of one dollar
(Canadian funds) paid by each party to the other, receipt of which is hereby
acknowledged,

o     CIMYM shall have an unlimited  number of common shares,  the initial issue
      of which shall be as to 80% to YM and as to 20% to CIMAB.


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o     No issued and  outstanding  shares in the  capital of CIMYM shall be sold,
      transferred  or  otherwise  disposed of to any person  without the written
      consent of each of YM and CIMAB.

o     The issue of any  additional  common  shares in the capital of CIMYM shall
      first be to each of YM and CIMAB in proportion to their shareholdings, and
      thereafter  to any other  person,  but only with the consent of both of YM
      and CIMAB, such consent not to be withheld unreasonably.

o     The board of directors of CIMYM shall consist of five directors,  three of
      whom shall be nominees of YM, two of whom shall be nominees of CIMAB.  The
      initial  diirectors of CIMYM shall be as set out in Appendix A hereto. The
      election of directors shall take place annually.  The board is required to
      meet once per year,  and  otherwise as often as deemed  necessary  for the
      conduct of the  business  of the joint  venture  in.

      In witness  wherof the parties  hereto  have  executed this  Agreement  by
      duly authorized officers or representatives thereof.

CIMAB S.A.                                           YORK MEDICAL INC..
duly authorized to sign                              duly authorized to sign





                                   CIMYM INC.

                                   duly authorized to sign


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                                   APPENDIX A

                          Dra. Patricia Sierra Blazquez

                           Lic. Norkis Arteaga Morales

                              Ezra Solomon Lwowski

                                Hugh B. Anderson

                          Diane Joan Kalina (President)