SC 13G
BB BIOTECH AG filed this form SC 13G on 14 Feb 2001
- velhartice.info
<PAGE>   2


CUSIP No.       584688105
          -----------------------


<TABLE>
<S>                                           <C>
         1.       Names of Reporting Persons             BB BIOTECH AG
                                             --------------------------------------------------

                  I.R.S. Identification Nos. of above persons (entities only):         N/A
                                                                               ----------------


         2.       Check the Appropriate Box if a Member of a Group (See Instructions)

                  (a)   [X]

                  (b)   [ ]


         3.       SEC  Use Only
                                ----------------------------------------------------------------


         4.       Citizenship or Place of Organization                SWITZERLAND
                                                       -----------------------------------------

         Number of Shares Beneficially        5.    Sole Voting Power                 0
         Owned by Each Reporting Person                                       ------------------
         with:                         

                                              6.    Shared Voting Power           5,204,837
                                                                              ------------------


                                              7.    Sole Dispositive Power            0
                                                                              ------------------
                                       
                                       
                                              8.    Shared Dispositive Power      5,204,837
                                                                              ------------------

         9.     Aggregate Amount Beneficially Owned
                by Each Reporting Person                             5,204,837
                                                    --------------------------------------------


         10.    Check if the Aggregate Amount in Row (9) Excludes Certain Shares     [   ]


         11.    Percent of Class Represented by amount in Row (9)              17.2%
                                                                  ------------------------------


         12.    Type of Reporting Person (See Instructions)                    HC,CO
                                                            ------------------------------------
</TABLE>


                                      2