1 EXHIBIT 3

   1
                                    EXHIBIT 3

                             JOINT FILING AGREEMENT 


           We, the undersigned, hereby express our agreement that the attached
Schedule 13D (including all amendments thereto) is filed on behalf of each of
the undersigned.





                                                           
                                                              BB MEDTECH AG

  Date:   July 7, 1998                                        By:      /s/ H. Xxxx Xxxx
                                                                       ----------------

                                                              Name:    H. Xxxx Xxxx


  Date:   July 7, 1998                                        By:      /s/ Xx. Xxxxxx Xxxxxxxxxx
                                                                       -------------------------

                                                              Name:     Xx. Xxxxxx Xxxxxxxxxx


                                                              MEDSOURCE S.A.

  Date:   July 7, 1998                                        By:      /s/ H. Xxxx Xxxx
                                                                       ----------------

                                                              Name:    H. Xxxx Xxxx


  Date:   July 7, 1998                                        By:      /s/ Xx. Xxxxxx Xxxxxxxxxx
                                                                       -------------------------

                                                              Name:     Xx. Xxxxxx Xxxxxxxxxx