AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

     THIS  AMENDMENT,  effective  January 1, 2000,  is entered into by and among
Ohio Litho,  Inc., a Delaware  corporation,  the General  Partner of Ohio Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                    RECITALS:
                                    --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

     B. The Partners desire to amend the Agreement to substitute the Partnership
as the  holder  of the  right of first  refusal  under  of  Section  9.03 of the
Agreement.

                  NOW, THEREFORE, the Partners agree as follows:

     1. Section 9.03 of the Agreement is hereby amended by deleting  subsections
(b) and (c) thereof in their entirety and by substituting the language set forth
below:

                  (b) Upon receipt of such notice,  the  Partnership  shall have
         the right and option, exercisable at any time during a period of thirty
         (30) days from the date of the  Selling  Partner's  notice of the Offer
         (the "Option  Period"),  to purchase all or any portion of the Purchase
         Interest.  If the Partnership  elects to exercise its option,  it shall
         give  written  notice to the Selling  Partner and the sale and purchase
         shall be closed  within  thirty  (30) days  after the end of the Option
         Period.  Any purchase  made under this  paragraph  shall be on the same
         terms and conditions as contained in the Offer.

                  (c) If the  Partnership  does not elect to purchase all of the
         Purchase  Interest,  the Selling  Partner shall be free for a period of
         sixty (60) days after the expiration of the foregoing notice periods to
         sell the Purchase Interest to the purchaser named in the Offer upon the
         terms and conditions contained in the Offer, subject to the requirement
         of consent by the General Partner  pursuant to Section 9.02;  provided,
         that the said  purchaser  qualifies  as a Qualified  Purchaser.  In the
         event that the sale is not consummated within such sixty




<PAGE>


         (60)-day period, no sale shall be made without again complying with the
         provisions of this Section 9.03.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                    OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                     By:_________________________________ (SEAL)

                                        ---------------------------------
                                              (Type Name and Title)

<PAGE>


                         AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

THIS  AMENDMENT,  effective  January 1, 2000,  is entered into by and among Ohio
Litho,  Inc.,  a  Delaware  corporation,  the  General  Partner  of Ohio  Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.

                                                     RECITALS:
                                                     --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

     B. The  Partners  desire to amend the  Agreement  to delete in its entirety
Section 10.02(g) of the Agreement.

                  NOW, THEREFORE, the Partners agree as follows:

     1. Section 10.02(g) of the Agreement is hereby deleted in its entirety with
the effect that such provision shall be void and of no effect.

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                     OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                     By:_________________________________ (SEAL)

                                        ---------------------------------
                                                 (Type Name and Title)





<PAGE>
                         AMENDMENT TO FIRST AMENDED AND
                    RESTATED AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         OHIO MOBILE LITHOTRIPTER, LTD.

     THIS  AMENDMENT,  effective  February 1, 2000, is entered into by and among
Ohio Litho,  Inc., a Delaware  corporation,  the General  Partner of Ohio Mobile
Lithotripter,  Ltd., a Texas limited  partnership (the  "Partnership"),  and the
Limited Partners of the Partnership.
                                                     RECITALS:
                                                     --------

                  A. The General Partner and the Limited  Partners,  hereinafter
collectively  referred to as the  "Partners,"  entered into that  certain  First
Amended and Restated  Agreement of Limited  Partnership dated August 1, 1991, as
heretofore  amended  (the  "Agreement").  Capitalized  terms used herein and not
otherwise defined shall have the meanings given them in the Agreement.

                  B. The  Partners  desire  to amend the  Agreement  to effect a
redesignation of the Partnership's geographic service area as defined in Section
16.16(a)  effective  on the date  appropriate  consents  are  received  from the
General Partner and Two Thirds in Interest of the Limited Partners.

                  NOW, THEREFORE, the Partners agree as follows:

     1.  Section  16.16(a) of the  Agreement  is hereby  amended by deleting the
following language from the last sentence thereof:

                    "(excluding any territory located in Cuyahoga County, Ohio)"

                  IN WITNESS WHEREOF, the Partners have hereunto set their hands
and seals effective as of the date first written above.

                                    OHIO LITHO, INC., as General Partner and as
                                      Attorney-In-Fact for the Limited Partners


                                   By:_________________________________ (SEAL)

                                      ---------------------------------
                                            (Type Name and Title)





<PAGE>