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                                                                   EXHIBIT 10.13

                            STOCK PURCHASE AGREEMENT


         This Stock Purchase Agreement (the "Agreement") is entered into by and
between MAII Holdings, Inc., a Texas corporation (the "Corporation"), and
Christie S. Tyler ("Tyler"), as of February 1, 2001.

                                     RECITAL

         To provide incentive for Tyler to serve as the chief executive officer
of the Corporation, the Corporation desires to issue to Tyler, and Tyler desires
to purchase from the Corporation, 680,000 shares of the common stock, par value
$0.002 per share (the "Common Stock"), of the Corporation on the terms and
conditions set forth in this Agreement.

         1. Issuance of Shares. The Corporation hereby issues to Tyler in
exchange for the Purchase Price, 680,000 shares of Common Stock (the "Shares").
The purchase price of the Shares is $4.03 per Share, for a total purchase price
of $2,740,400 (the "Purchase Price"). The Purchase Price shall be paid
simultaneously with the execution of this Agreement by the parties hereto. Tyler
shall pay the Purchase Price by delivering to the Corporation (i) $1,360 in
cash; and (ii) a promissory note in the original principal amount of $2,739,040,
and in the form attached hereto as Exhibit A and incorporated by reference
herein (the "Note"). The Note shall be secured by a security interest in the
Shares pursuant to a Pledge and Security Agreement in the form attached hereto
as Exhibit B and incorporated by reference herein.

         2. Delivery of Certificates. Simultaneously with the execution of this
Agreement, the Corporation shall deliver to Tyler certificates evidencing the
Shares. The Shares for all purposes shall be considered issued on the date of
this Agreement.

         3. Put by Tyler. The parties hereto acknowledge and agree that Tyler
may, on or prior to April 12, 2001, purchase shares of Common Stock from current
shareholders of the Corporation. To the extent that Tyler does so, Tyler may, on
or prior to April 12, 2001, sell to the Corporation, for the price of $4.03 per
share, that number of Shares equal to the number of shares of Common Stock which
Tyler purchased from shareholders of the Company. The option granted Tyler
pursuant to this Section 3 (the "Put") shall be exercised by Tyler delivering
written notice of his intent to exercise to the Corporation at the address set
forth in Section 4, on or prior to April 12, 2001. Such notice shall specify the
number of shares to be sold to the Corporation. Such sale and purchase shall be
closed at a time and place agreeable to the parties no later than 15 days after
receipt by the Corporation of such notice. Notwithstanding anything contained
herein, the price to be paid by the Corporation upon exercise of the Put, shall
first be applied to the outstanding balance of unpaid accrued interest and
principal on the Note, and the balance, if any, shall be paid to Tyler in cash.
The Put shall apply only to the Shares and no other shares of common stock of
the Corporation, and may not be transferred or assigned by Tyler. No holder of
the Shares, other than Tyler, may exercise the Put.

         4. Notices. All notices required or permitted hereunder shall be in
writing and shall be deemed to be delivered when delivered in person, or when
deposited in the United States mail, postage prepaid, registered or certified
mail, return receipt requested, addressed as follows:


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         If to Tyler:                        Christie S. Tyler
                                             5823 Encore Drive
                                             Dallas, Texas  75240


         If to the Corporation:              MAII Holdings, Inc.
                                             c/o Jackson Walker L.L.P.
                                             901 Main Street Suite 6000
                                             Dallas, Texas  75202
                                             Attn:  Richard F. Dahlson

         5. Entire Agreement. This Agreement contains the entire agreement
between the parties with respect to the subject matter hereof and supersedes all
prior agreements, understandings and statements, written or oral, with respect
thereto.

         6. Severability. In the event that one or more of the provisions of
this Agreement shall, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalid, illegal or unenforceable provision
shall not affect any other provision hereof, and this Agreement shall be
construed as if such invalid, illegal, or unenforceable provision had never been
contained herein.

         7. Further Assurances. Tyler and the Corporation agree to take all
actions reasonably necessary to effectuate the intents and purposes of this
Agreement.

         8. Texas Law to Apply. This Agreement shall be construed under and in
accordance with the laws of the State of Texas, and all obligations of the
parties created hereunder are performable in Dallas County, Texas.

         9. Headings. The headings used in this Agreement are used for
administrative purposes only and do not constitute substantive matter to be
considered in construing the terms of this Agreement.

         10. Parties Bound. This Agreement shall be binding upon and shall inure
to the benefit of the parties hereto and to the extent permitted by this
Agreement, their successors and assigns.

         11. Amendment. This Agreement may be amended or modified only by a
writing executed by the parties.

         12. Waiver. No term or condition of this Agreement shall be deemed to
have been waived by a party, nor shall there be any estoppel against the
enforcement by a party of any provisions of this Agreement, except by written
instrument executed by the other party. No such written waiver by a party shall
be deemed a continuing waiver unless specifically stated therein, and each such
waiver shall operate only as to the specific terms or conditions waived and
shall not constitute a waiver of such terms or conditions for the future or as
to any act other than that specifically waived.


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         13. Counterparts. This Agreement may be executed in multiple
counterparts all of which shall constitute one agreement and each of which shall
constitute an original of this Agreement.

         Dated as of the date first written above.


                                   MAII HOLDINGS, INC.


                                   By: /s/ RICHARD F. DAHLSON
                                      ------------------------------------------
                                   Its: Director
                                       -----------------------------------------

                                    /s/ CHRISTIE S. TYLER
                                   ---------------------------------------------
                                       Christie S. Tyler



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