Exhibit 10.72

                            SHARE EXCHANGE AGREEMENT

         This  Share  Exchange  Agreement  (this  "Agreement")  is made  and
entered  into as of the 31st  day of August, 1999, by and between American
Physicians Service Group,  Inc., a Texas corporation  ("APS") and M. Reza
Jafarnia, M.D. (the "Shareholder").

                                R E C I T A L S:
                                 - - - - - - - -

         WHEREAS,  pursuant to that certain Asset Purchase Agreement (the "Asset
Purchase  Agreement")  dated  August 1, 1998,  entered into by  Shareholder  and
Syntera HealthCare Corporation,  a Texas corporation ("Syntera"),  and the other
contracts and agreements to which  Shareholder is a party as contemplated in the
Asset  Purchase  Agreement  (the  Asset  Purchase  Agreement  and all such other
contracts  and  agreements  are  hereinafter  referred  to  collectively  as the
"Acquisition  Documents"),  Shareholder  acquired  92,557  shares (the  "Syntera
Shares") of the $0.001 par value per share common stock of Syntera; and

         WHEREAS,  in  connection  with  the  execution  of the  Asset  Purchase
Agreement,  APS  and  Shareholder  entered  into  that  certain  Share  Exchange
Agreement dated August 1, 1998 (the "Original Agreement"); and

         WHEREAS,  APS and  Shareholder  have agreed to  terminate  the Original
Agreement upon the execution of this Agreement; and

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         WHEREAS,  at the  time of  execution  of this  Agreement,  Syntera  and
Shareholder  (in his capacity as a shareholder of Syntera) are  contemplating  a
proposed merger (the "Merger")  between Syntera and a subsidiary of FemPartners,
Inc., a Delaware corporation  ("FemPartners"),  pursuant to which Syntera may or
may not be the surviving corporation; and

         WHEREAS,  notwithstanding  the  Merger  and any effect it might have on
Shareholder's rights under the Original Agreement,  APS has agreed, on the terms
and subject to the conditions  hereof,  to exchange cash,  certain shares of its
$0.10 par value per share common stock ("APS  Common"),  shares of common stock,
par value $0.01, of Prime Medical  Services,  Inc., a Delaware  corporation (the
"Prime Stock"), or a combination  thereof, as determined by APS, for the Subject
Shares (as hereinafter defined).

         NOW,  THEREFORE,  in  consideration of the foregoing and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

         1.  TERMINATION  OF SHARE  EXCHANGE  AGREEMENT.  Contemporaneous  with
and  contingent  only upon the execution  of this  Agreement,  the  Original
Agreement  is hereby  terminated  and  revoked,  and all  rights and privileges
of the parties thereto are nullified.

         2.  EFFECT  OF  MERGER.  In the event  the  Merger  occurs on or before
December 31, 1999,  the shares of  FemPartners  received by  Shareholder  in the
Merger,  in return for the Syntera shares (the "FemPartners  Shares"),  shall be
treated as Syntera Shares for all purposes

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hereunder.  As used herein,  "Subject  Shares"  shall refer  exclusively  to the
Syntera  Shares,  unless the Merger  occurs on or before  December 31, 1999,  in
which event "Subject Shares" shall,  after the Merger,  refer exclusively to the
FemPartners Shares. As used herein, "Gross Exchange Value" shall mean the amount
of  $462,785,  and such  amount  shall not be adjusted in the event of any stock
dividends,  stock splits, reverse stock splits or recapitalizations to which the
Subject Shares are subject after the date of this Agreement.

         3.   CONDITIONS TO EXCHANGE  RIGHT.  In addition to the other terms and
conditions  contained in this Agreement,  Shareholder  shall only be entitled to
exchange the Subject Shares if each of the following  conditions has been
satisfied:

                  (a) There shall not have been, on or before  December 31, 2000
(the "Determination Date"), any registered public offering of shares of the same
class as the Subject Shares, or any other transaction or event pursuant to which
shares of the same class as the Subject Shares shall have become publicly traded
at a per share price (existing  immediately  after such public offering or other
transaction  or event)  which would yield an amount equal to or greater than the
Gross Exchange Value upon a sale of all of the Subject Shares at such price; and

                  (b) Shareholder shall not have remained,  at any time prior to
the date of the closing of any exchange of stock pursuant to this Agreement (the
"Closing  Date"),  in breach of, or default under,  this  Agreement,  any of the
Acquisition  Documents or any other  contract or agreement to which  Shareholder
and  Syntera,  FemPartners,  APS and/or  any of their  affiliates  are  parties,
following delivery by APS of ten (10) days written notice of such breach or

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default,  and  Shareholder  shall not, on the Closing  Date,  be in breach of or
default under this Agreement, any of the Acquisition Documents or any such other
contract or agreement  (provided,  that in such event,  Shareholder shall have a
period of ten (10) days  following  delivery by APS of written notice thereof to
cure such breach or default and close the share exchange hereunder); and

                  (c) At the Closing Date,  Shareholder  has all requisite legal
capacity  and  authority  to engage  in the  transactions  contemplated  by this
Agreement,  is the owner of all the Subject  Shares,  and the Subject Shares are
free of any and all liens, claims or encumbrances of any kind whatsoever; and

                  (d) If the Merger has not occurred on or prior to December 31,
1999, then on or before the Closing Date,  Syntera shall not be, or have been, a
party to any merger,  consolidation  or similar  transaction,  or agreement with
respect  thereto,  pursuant to which  Syntera was not or would not be, the named
surviving entity after such merger, consolidation or other transaction.

         4. EXCHANGE  NOTICE.  In the event all of the  conditions  described in
Section 1 are satisfied as of the Determination  Date and Shareholder  elects to
exercise its right to exchange its  Exchangeable  Subject Shares (as hereinafter
defined),  Shareholder  shall  provide  written  notice  thereof (the  "Exchange
Notice") to APS,  which  Exchange  Notice must be received by APS not later than
the date (the "Expiration Date") which is one hundred eighty (180) calendar days
after the  Determination  Date. In the event (i) any of the conditions  required
for an exchange to be permissible,  as described in Section 1 above,  fail to be
satisfied on or prior to the Determination

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Date, or (ii) any of the conditions specified in subsections (b), (c) and (d) of
Section 1 fail to be  satisfied  on or prior to the Closing  Date,  or (iii) APS
fails  to  receive  an  Exchange  Notice  from  Shareholder  on or  prior to the
Expiration Date; then, in any such case, all of Shareholder's  rights under this
Agreement  shall  automatically  terminate  and be of no further force or effect
whatsoever.

         5.    SHARE EXCHANGE.

         (a) Shareholder's  right to exchange its Subject Shares hereunder shall
apply as to all, but not less than all, of the Subject Shares which are eligible
for exchange as described in this  subparagraph  (a).  Assuming  Shareholder has
complied with all of the  conditions  allowing for an exchange  pursuant to this
Agreement, all of the Subject Shares are eligible for exchange.

         (b) In the event  Shareholder  has complied with all of the  conditions
allowing  for an exchange  pursuant to this  Agreement,  the closing of any such
exchange (the "Closing") shall occur at the offices of APS in Austin,  Texas, on
such day and at such time as the parties  hereto may mutually  agree upon, or in
the failure to so agree, at 10:00 a.m. Austin,  Texas time on the first business
day that falls thirty (30) days after the later of (y) the Expiration  Date, (z)
if a Lock-Up Period (as  hereinafter  defined) is imposed  pursuant to Section 6
hereof,  the day on which such Lock-Up Period ends, or (z) if a Market Delay (as
hereinafter  defined) is imposed  pursuant to Section  5(c)  hereof,  the day on
which such  Market  Delay  ends.  The  maximum  number of Subject  Shares  which
Shareholder has the right to exchange pursuant to subparagraph (a) of this

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Section are hereinafter referred to as the "Exchangeable Subject Shares." At the
Closing, Shareholder shall be entitled to receive either:

                  (i) such shares of APS Common as is determined by dividing the
Gross Exchange Value by the average of the "bid" and "ask" prices for APS Common
as quoted by the National  Association of Securities Dealers Automated Quotation
System  at the  close of  trading  on each of the last  five (5)  business  days
immediately preceding the Closing Date; or

                  (ii) such shares of Prime Stock as is  determined  by dividing
the Gross  Exchange  Value by the average of the "bid" and "ask"  prices for the
Prime  Stock  as  quoted  by the  National  Association  of  Securities  Dealers
Automated  Quotation System at the close of trading on each of the last five (5)
business days immediately preceding the Closing Date; or

                  (iii) cash or immediately available funds in the amount of the
Gross Exchange Value; or

                  (iv) any combination thereof (as determined by APS in its sole
discretion), equal in aggregate value to the Gross Exchange Value.

         (c) In the event APS  elects to  satisfy  its  obligations  under  this
Section 5 in whole or in part with the issuance to  Shareholder of shares of APS
Common or Prime common stock,  APS shall have the right to delay the Closing for
up to ninety (90) calendar days after the Expiration Date (the "Market  Delay"),
if, in APS' sole discretion, an issuance of shares of APS Common or Prime common

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stock pursuant to this Agreement,  or in combination with any similar  agreement
or  agreements,  would  depreciate  the market  value of the APS Common or Prime
common stock, as applicable.

         (d) At the Closing,  Shareholder shall tender its share  certificate(s)
for all of the Exchangeable  Subject Shares, duly endorsed in blank, to APS, and
shall also provide APS with an executed blank stock power, in form and substance
reasonably acceptable to APS, wherein Shareholder represents and warrants to APS
(i) that  Shareholder has all necessary  legal capacity,  power and authority to
engage in the transactions  contemplated  hereby, and (ii) that Shareholder owns
all  interests  in  and  to  the  Exchangeable   Subject  Shares  and  that  the
Exchangeable  Subject Shares are being  transferred to APS free and clear of all
liens, claims or encumbrances of any kind whatsoever.

         (e) Any shares of APS Common or Prime Stock that  Shareholder  receives
in the exchange  are  hereinafter  referred to as the "New  Shares." The parties
acknowledge and agree that Shareholder shall receive a whole number of shares of
New Shares  only,  and that any  fractional  share  amounts  resulting  from the
foregoing exchange  calculation shall be rounded up or down, as the case may be,
to the next whole  number of shares.  At the Closing,  Shareholder  shall either
receive a share certificate or certificates for all its New Shares or, if APS is
unable to produce (or caused to be produced) such certificate or certificates by
the Closing  Date,  will receive a copy of a registered  letter sent from APS to
the transfer agent instructing the transfer agent to deliver such certificate or
certificates in the name of Shareholder directly to Shareholder or Shareholder's

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designee  (and APS shall  ensure that  Shareholder  subsequently  receives  such
certificate or certificates).

         6. NEW SHARES  TRANSFERABILITY.  APS will have registered any shares of
APS Common exchanged  hereunder with the Securities and Exchange Commission (the
"Commission"),  and made such  other  filings  and  taken  such  other  steps as
necessary,  so that Shareholder may immediately sell, or otherwise convey,  such
shares of APS Common without  restriction  (except as otherwise provided below).
Shareholder agrees to cooperate fully and in all respects with APS in connection
with any such  registration,  whether such  cooperation  is requested  before or
after the  Determination  Date.  Failure  of  Shareholder  to  cooperate  fully,
including  without   limitation,   promptly   providing  complete  and  accurate
information to APS, in connection with the registration of any APS Common shares
to be  received  hereunder,  whether  such  cooperation  and/or  information  is
requested before or after the Determination  Date or before or after Shareholder
delivers any Exchange Notice, shall automatically  terminate Shareholder's right
to receive stock under this  Agreement that is registered  with the  Commission.
Notwithstanding anything contained herein to the contrary, in the event that APS
is in the process,  either at the Closing Date or at the Determination  Date, of
registering  and/or  selling  any of its  capital  stock in or  pursuant  to any
underwritten  public offering,  upon the written request of the lead underwriter
involved therein,  Shareholder  agrees,  and shall then agree in writing in form
and substance  reasonably  acceptable  to APS, to not sell,  attempt to sell, or
solicit or accept any offers to sell or otherwise  convey,  any of its shares of
APS Common for such period of time (not to exceed one hundred eighty (180) days)
as may be requested by such lead underwriter (the "Lock-Up  Period").  Any Prime
Stock exchanged hereunder will be registered with

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the Commission and will be free of any and all liens,  encumbrances and security
interests,  so that  Shareholder may immediately  sell or otherwise  convey such
Prime Stock without restriction.

         7.    MISCELLANEOUS.

                  (a) FEES AND  EXPENSES.  Each party hereto  agrees to bear all
fees and expenses  (including  without  limitation all fees and expenses for its
legal counsel and any accountants or other  professional  advisors)  incurred in
connection with the transactions  contemplated hereby;  provided,  however, that
APS shall bear all costs and expenses associated with registering any APS Common
shares  to be  registered  hereunder  (excluding  the fees and  expenses  of any
personal  counsel or accountants of  Shareholder,  and any broker's  commissions
incurred upon any subsequent sale of such APS Common shares by Shareholder).

                  (b) GOVERNING LAW AND VENUE.  This Agreement shall be governed
by, and  construed  and enforced in  accordance  with,  the laws of the State of
Texas  (except  the  laws  of  Texas  that  would  render  such  choice  of  law
ineffective).  This Agreement  shall be performable in, and venue for any action
relating to this Agreement shall be proper only in, Montgomery County, Texas.

                  (c)    COUNTERPARTS.    This   Agreement   may   be   executed
simultaneously  in one or more  counterparts,  each of which  shall be deemed an
original,  and  all  of  which  together  shall  constitute  one  and  the  same
instrument.

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                  (d)  INUREMENT.  This  Agreement  shall  be  binding  upon the
parties hereto and their respective heirs, legal representatives, successors and
permitted  assigns.  No party hereto may assign this Agreement,  or any of their
rights or obligations  hereunder,  without the express prior written  consent of
all parties hereto in each instance.

                  (e)  NOTICES.  Any notices  required or  permitted to be given
under this Agreement  shall be given in writing and shall be deemed received (a)
when  personally  delivered  to the  relevant  party at its address as set forth
below or (b) if sent by mail, on the third day following the date when deposited
in the United States mail, certified or registered mail, postage pre-paid to the
relevant party at its address indicated below:

         APS:                 American Physicians Service Group, Inc.
                              1301 Capital of Texas Highway, Suite C-300
                              Austin, Texas 78746-6550

                                 Attn: President

         Shareholder:         M. Reza Jafarnia, M.D.
                              9041 Briar Forrest Drive
                              Houston, TX 77024

Any party may change its address for purposes of this Agreement by proper notice
to the other party.

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         IN WITNESS  WHEREOF,  the parties hereto have executed this  Agreement,
intending to be legally bound hereby, as of the date first above written.

APS:                        AMERICAN PHYSICIANS SERVICE GROUP, INC.

                            By:           /s/ W.H. Hayes
                                         ------------------------

                            Printed Name: W.H. Hayes
                                         ------------------------

                            Title:        Sr. VP - Finance
                                         ------------------------

SHAREHOLDER:
                                          /s/  M. Reza Jafarnia, M.D.
                                         ----------------------------