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                                                                   EXHIBIT 10.43




                               SUBLEASE AGREEMENT


This Agreement of Sublease ("Sublease"), made as of the 13th day of July, 1998,
by and between FIBREBOARD CORPORATION, a Delaware Corporation, One Owens
Corning Parkway, Toledo, Ohio (hereinafter referred to as "Sublessor") and
AMERICAN PHYSICIAN PARTNERS, INC., a Delaware corporation, 2301 NationsBank
Plaza, 901 Main Street, Dallas, Texas 75202-3721 (hereinafter referred to as
"Sublessee").

                              W I T N E S S E T H:

WHEREAS, The Equitable - Nissei Dallas Company, a joint venture, as Lessor
("Lessor") and Fibreboard Corporation, as Lessee, entered into that certain
lease (the "Lease") dated June 10, 1996 regarding 2200 Ross Avenue, Suite 3600,
Dallas, Texas (the "Premises");

WHEREAS, the Lease is attached hereto as Exhibit A hereof and is hereinafter
referred to as the "Dominant Lease"; and

WHEREAS, the Lessor and the Lessee entered into that certain First Amendment of
Lease dated April 17, 1997, pursuant to which Lessee leased from Lessor an
additional 5,321 square feet of rentable area at 2200 Ross Avenue, Suite 3600,
Dallas, Texas, and, as a result, the "Subleased Premises," as defined and used
herein, includes the additional 5,321 square feet so that the "Subleased
Premises" consists of approximately 25,812 square feet of rentable area located
on the 36th Floor of 2200 Ross Avenue; and

WHEREAS, Sublessor is desirous of subletting to Sublessee the Subleased
Premises;

NOW, THEREFORE, in consideration of the foregoing premises, the mutual promises
hereinafter made and other good and valuable consideration, the parties agree
as follows:

1.       SUBLEASE OF SUBLEASED PREMISES.  Sublessor, in consideration of the
         sub-rents to be paid and the agreements to be performed by Sublessee,
         and subject to and upon all of the terms and conditions hereof, does
         hereby sublease to Sublessee, and Sublessee hereby Subleases from
         Sublessor, the Subleased Premises.  Sublessee shall use the Subleased
         Premises only as is permitted in Section 9 of the Dominant Lease.

2.       TERM.  The term of this Sublease ("Term") shall be for a period of one
         hundred fifty-seven (157) months commencing on August 1, 1998 (the
         "Commencement Date") and ending August 31, 2011 ("Expiration Date").

3.       NET RENT. Sublessee shall pay to Sublessor monthly rent in advance, on
         the first day of each month during the Term, in accordance with the
         Rent Schedule attached hereto as Exhibit B. Rent under this Sublease
         shall be paid without deduction or set-off, except to the extent
         allowed "Lessee" in the Dominant Lease, in which event there shall be
         a dollar-for-dollar reduction in the amount of rent payable hereunder
         during any period of the Term when rent is not payable by Sublessor
         thereunder.  Prior to the Commencement Date, Sublessor shall permit
         Sublessee without payment of rent to have access (with keys) and to
         occupy for the purpose of inspecting the Subleased Premises and, at
         Sublessee's expense and risk, the Subleased Premises (i) to begin work
         on cabling and other computer-related
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         installation; (ii) to move certain personalty of Sublessee's into the
         Subleased Premises; and (ii) for storage use and fixturing prior to
         the Commencement Date.  Should the Commencement Date occur on other
         than the 1st day of a calendar month or should the Expiration Date
         occur on any day except the last day of a calendar month, the monthly
         rent for that month shall be prorated based on the number of days
         Sublessee actually occupies the Subleased premises.  Upon Commencement
         Date, Sublessee shall have the right to fully occupy the entire
         Subleased Premises consisting of 25,812 rentable square feet;
         provided, however, Sublessee intends, and shall have the right, to
         advertise for and subsublease the approximately 5,300 square foot
         portion of the Subleased Premises which has its own separate entrances
         and exits (the "5,300 feet").  Any  rentals received by Sublessee from
         the 5,300 Feet from any subsubtenant shall belong solely to Sublessee,
         notwithstanding anything to the contrary contained in this Sublease or
         the Dominant Lease.

4.       ADDITIONAL RENTAL.

         A)      Sublessee shall also pay to Sublessor monthly as additional
                 rental the amount of electrical costs charged to Sublessor
                 pursuant to Section 4.C. of the Dominant Lease.

         B)      Sublessee shall also pay to Sublessor monthly as additional
                 rent all operating expense escalations charged to Sublessor
                 pursuant to Exhibit C of the Dominant Lease.

         C)      Notwithstanding anything contained in this Sublease or in the
                 Dominant Lease to the contrary, Sublessee shall not be
                 responsible for the payment of any additional rentals to the
                 Sublessor for the period of September 1, 1998 through November
                 30, 1999.

5.       SECURITY DEPOSIT. On the date of execution of this Sublease by
         Sublessee, there shall be due and payable by Sublessee to Sublessor a
         Security Deposit in an amount equal to $79,587.00 to be held by
         Sublessor for the performance by Sublessee of Sublessee's covenants
         and obligations under this Sublease and Dominant Lease.  Upon the
         confirmed occurrence of any event of default by Sublessee, Sublessor
         may, from time to time, without notice or prejudice to any other
         remedy, use said Security Deposit to the extent necessary to make good
         any arrears of rent or any other damage, injury, expense or liability
         caused to Sublessor by such default or misuse.  Any remaining balance
         of Security Deposit shall be returned to Sublessee at the end of the
         first four (4) years of the Term if there is then no default
         hereunder, and otherwise upon satisfactory compliance with the terms
         herein, inspection and acceptance by Sublessor of the vacated
         Subleased Premises.

6.       INCORPORATION AND OBSERVANCE OF DOMINANT LEASE. Sublessee accepts,
         assumes and agrees to perform and be bound by all the terms, covenants
         and conditions of the Dominant Lease which obligate the "Lessee"
         thereunder unless this Sublease expressly provides for terms,
         covenants or conditions which conflict with those of the "Lessee"
         under the Dominant Lease; all terms of the Dominant Lease being



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         incorporated herein by reference as though fully set forth herein.
         Sublessor agrees to exert reasonable efforts to obtain the performance
         of all the covenants of the "Lessor" pursuant to the provisions of
         said Dominant Lease.  In the event of conflict between the terms of
         this Sublease and those of the Dominant Lease, as between the
         Sublessor and Sublessee, the terms of this Sublease Agreement shall
         control.

7.       INSURANCE.  Sublessee agrees to keep the Subleased Premises insured
         with a reputable insurance company pursuant to a Tenants Comprehensive
         General Liability Insurance policy with a minimum limit of $1,000,000
         and All Risk Property policy insuring the contents contained within
         the Premises.  Such policies shall name Sublessor and Lessor as their
         interests may appear, as additional insureds under the policies and
         Sublessee shall provide Sublessor with a certificate evidencing such
         insurance.  The policies shall contain an agreement by the insurer
         that such policies cannot be canceled or materially changed without at
         least thirty (30) day's prior written notice to Sublessor.

8.       DEFAULT.  In addition to any default incorporated herein pursuant to
         Paragraph 6 above, Sublessee shall be in default under this Sublease
         if (a) Sublessee shall fail to pay, except as otherwise expressly
         provided herein, when due any monthly rent payment within the time and
         subject to the conditions applicable to Sublessor under the Dominant
         Lease; or (b) Sublessee shall fail to perform any of its other
         obligations under this Sublease after the same should have been
         performed in accordance with the terms hereof within the time and
         subject to the conditions applicable to Sublessor under the Dominant
         Lease.

9.       REMEDIES.  If Sublessee shall be in default hereunder after having
         been given notice of the existence of such default but with Sublessee
         not having cured such default within thirty (30) days after receipt of
         such notice, in addition to any other remedies that may be available
         to Sublessor at law or in equity, Sublessor shall have the right to
         immediately terminate this Sublease by written notice thereof to
         Sublessee.  In such event, Sublessee shall immediately quit and
         surrender the Subleased Premises upon the date set forth in such
         notice.

10.      INDEMNITY.  Sublessee shall indemnify and hold harmless Sublessor and
         Sublessor's affiliates, and their respective directors, officers,
         shareholders, employees, representatives and agents, from and against
         any and all damages, losses, costs, claims, liabilities and expense
         (including, without limitation, reasonable attorney's fees and
         disbursements) incurred in connection with or otherwise arising from
         (a) the occupancy and use of the Subleased Premises by Sublessee; and
         (b) the breach or default by Sublessee of any of its obligations or
         duties hereunder.

11.      CONDITION OF SUBLEASED PREMISES AND ALTERATIONS. Sublessor Shall
         deliver the Subleased Premises to Sublessee clean and free of debris
         on the Commencement Date.  Sublessor has no duty to construct or
         improve the Subleased Premises and the Sublease Premises shall be
         taken by Sublessee "As Is".





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12.      SURRENDER OF SUBLEASED PREMISES.  Subject to the requirements of
         Section 6 above, at the termination of this Sublease, by lapse of time
         or otherwise, Sublessee shall deliver up the Subleased Premises to
         Sublessor in as good condition as existed on the date of possession by
         Sublessee, ordinary wear and tear only excepted.  Upon such
         termination of this Sublease, Sublessor shall have the right to
         re-enter and resume possession of the Subleased Premises.

13.      ALTERATIONS TO SUBLEASED PREMISES.  The Sublessee may, with the prior
         written consent of the Sublessor and the Lessor, which consent shall
         not be unreasonably withheld by the Sublessor and subject to the terms
         of the Dominant Lease, at any time and from time to time during the
         Term of this Sublease, make such changes and alterations, structural
         or otherwise, to the Subleased Premises as the Sublessee shall deem
         necessary or desirable in its sole discretion in connection with the
         operation of Sublessee's business; provided that:

         A)      No change or alteration shall materially weaken, either
                 temporarily or permanently, the structure of the Subleased
                 Premises or, when completed, be of such character as to:

                 i)   affect adversely the value of the Subleased Premises
                      in a material manner; 
                 ii)  reduce the cubic content of the Building; or 
                 iii) reduce the general utility of the Subleased Premises.

         B)      Full sets of plans and specifications for any such changes and
                 alterations shall be supplied to the Sublessor and the Lessor.

         C)      Any interior or exterior structural alterations to the
                 Subleased Premises which are performed, or caused to be
                 performed, by the Sublessee shall become at once a part of the
                 realty and belong to Lessor.  Lessor under the Dominant Lease
                 may, however, at its discretion, require that any such
                 alterations be removed upon surrender of the Subleased
                 Premises by the Sublessee, without expense to Sublessor or to
                 Lessor, and that the Subleased Premises be restored to its
                 condition, as it existed prior to such alteration at
                 Sublessee's sole cost and expense.  Sublessee shall own and
                 retain title to all other leasehold improvements, moveable
                 furniture, trade fixtures, furnishings and equipment,
                 including those presently existing in the Subleased Premises
                 (collectively, the "Personalty"), providing Sublessee is not
                 in default under the terms of the Agreements.  Sublessee shall
                 be responsible for all personal property taxes with respect to
                 the Personalty from and after the effective date of this
                 Sublease, with such taxes prorated for the 1998 tax year.

         D)      Any such alteration or change must be completed in a
                 professional and workmanlike manner, and must be completed in
                 full compliance with all applicable laws, regulations and
                 building codes.

14.      HOLDOVER.  If this Sublease is terminated for any reason and Sublessee
         fails or refuses to vacate the Subleased Premises within five (5) days
         of such termination, Sublessor, in





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         addition to any other remedies available to it, shall be entitled to
         receive 135% of the rental due during the period in which Sublessee
         remains on the Subleased Premises in violation of this provision.
         There are no renewal options granted to Sublessee hereunder or under
         the Dominant Lease.

15.      BROKERS.  Only Fischer & Company was instrumental in arranging this
         Sublease, and Sublessee indemnifies and holds harmless Sublessor and
         Lessor from any claim for commission by any other broker, and
         Sublessor is solely responsible for any commission due to Fischer &
         Company as a result of this Sublease.

16.      NOTICES.  All notices required or permitted to be given hereunder
         shall be given in writing and, if not delivered by hand, shall be
         deposited, either registered or certified, in the United States mail,
         postage prepaid, and addressed to Sublessor or Sublessee, as the case
         may be, at its above address.

17.      HAZARDOUS MATERIALS.  SUBLESSEE SHALL NOT CONDUCT ANY ACTIVITIES ON OR
         ABOUT THE SUBLEASED PREMISES WHICH RESULT IN THE GENERATION, STORAGE
         OR RELEASE OF ANY TOXIC, HAZARDOUS OR SIMILAR SUBSTANCES (AS SUCH
         TERMS MAY BE DEFINED FROM TIME TO TIME BY ANY FEDERAL, STATE OR LOCAL
         LAW, RULE OR REGULATION).  SUBLESSEE SPECIFICALLY AGREES TO INDEMNIFY,
         DEFEND AND HOLD SUBLESSOR AND LESSOR HARMLESS FROM AND AGAINST ANY AND
         ALL CLAIMS, DAMAGES, LIABILITIES AND LOSES ARISING AS A RESULT OF
         SUBLESSEE'S BREACH OF THE FOREGOING PROHIBITION.

18.      ASSIGNMENT.  Sublessee shall not assign this Sublease nor sublet all
         or any part of the Subleased Premises without the prior written
         consent of Sublessor, which consent shall not be unreasonably
         withheld; provided that, Sublessee may sublet subject to the terms,
         covenants and conditions of this Sublease all or any part of the 5,300
         feet, provided Sublessee remains obligated to Sublessor for the rental
         and other obligations of Sublessee hereunder respecting the 5,300
         Feet.  With respect to any proposed subletting, Sublessee shall notify
         Sublessor in writing at least forty-five (45) days prior to the
         proposed commencement date of the new tenant's occupancy, and identify
         the tenant, the nature of the tenant's business and the proposed use
         of the new tenant's space.  Sublessor shall approve or disapprove of
         the proposed subletting in writing within fifteen (15) days after
         receipt of Sublessee's notice.  However, Sublessor shall have the
         right, at any time, to assign this Sublease to any other party without
         the consent of Sublessee.

19.      LESSOR'S CONSENT.  Sublessor and Sublessee each acknowledge and agree
         that this Sublease is subject to the Sublessor obtaining the prior
         written consent of Lessor in accordance with the terms of the Dominant
         Lease.  Such written consent shall be accompanied by the Lessor's
         acknowledgment that there are no defaults by or offsets against
         Sublessor under the Dominant Lease.  In the event that such consent is
         not obtained within thirty (30) days following the date hereof, but in
         any event prior to the Commencement Date, this Sublease shall
         terminate and neither party shall have any liability to the other
         hereunder.





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20.      SUBLESSOR'S OBLIGATIONS.  Sublessor agrees during the Term to:

         A)      Promptly provide Sublessee any notice or other communications
                 respecting the Dominant Lease received by Sublessor from
                 Landlord or any mortgagee of Landlord.

         B)      Cooperate with and assist Sublessee to perform Sublessee's
                 obligations under the Dominant Lease in any endeavor, such as
                 in the event of condemnation or casualty proceeds, wherein
                 Sublessor's participation is necessary in Sublessor's name
                 either under the Dominant Lease or by law.

21.      SUBLESSOR'S REPRESENTATIONS.  Sublessor represents that:

         A)      Sublessor will pay any amounts to be paid to Landlord under
                 subparagraph 10.a. of the Dominant Lease.

         B)      Sublessor will indemnify Sublessee for damages resulting from
                 Sublessor's default under the Dominant Lease through no fault
                 of Sublessee, including but not limited to, Sublessor's acts
                 or omissions of the type specified in subparagraph 11.c. of
                 the Dominant Lease.

         C)      This Sublease does not violate the terms of any mortgage
                 encumbering the Premises, those of any agreement between
                 Sublessor and any mortgagee of Landlord, nor those of any
                 other agreement with any other creditor of Sublessor's holding
                 a lien against or a security interest in the Premises.

         D)      All payments due and owing under the Dominant Lease have been
                 made, and Sublessor is not in default thereunder.

         E)      It will provide Sublessee by the Commencement Date an estoppel
                 letter from Lessor, specifying the address for monthly rent
                 due hereunder, approving this Sublease, and acknowledging that
                 so long as Sublessee is not in default hereunder, a default
                 under the Dominant Lease by Sublessor will not result in the
                 termination of Sublessee's tenancy so long as Sublessee
                 attorns to Lessor under the terms hereof.

         F)      The Subleased Premises comply with the Americans With
                 Disabilities Act.

22.      SUBLESSEE'S RIGHT TO TERMINATE.  Sublessee shall have the same rights
         to terminate this Sublease as Sublessor would have under the Dominant
         Lease for Landlord's acts or omissions as are specified in the
         Dominant Lease or as otherwise provided to Sublessor by Law.





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23.      REFURBISHMENT AND CONSTRUCTION ALLOWANCE.  On the seventh (7th)
         anniversary of the Commencement Date of the Dominant Lease, Sublessor
         shall pay to Sublessee a lump sum of $102,455.00 in cash as an
         allowance to refurbish the Subleased Premises, as such sum becomes
         available to Sublessor under the Dominant Lease and any amendments
         thereto.  In addition, from and after the Commencement Date of this
         Sublease, Sublessor shall make available the sum of $53,210 to
         Sublease as a construction allowance to be disbursed to Sublessee from
         time to time during the Term of this Sublease (if not utilized within
         the first six months after the Commencement Date by Sublessee) for
         Sublessee's improvements to the Subleased Premises.


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IN WITNESS WHEREOF, the parties hereto have hereunto set their hands and seals
the day and year first above written.



SUBLESSOR:                        FIBREBOARD CORPORATION
                                  
                                  
                                  
                                  By:                                          
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                                  Title:                                       
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                                  Date:                                        
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SUBLESSEE:                        AMERICAN PHYSICIAN PARTNERS, INC.
                                  
                                  
                                  
                                  
                                  By:                                          
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                                  Title:                                       
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                                  Date:                                        
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LESSOR:                           The EQUITABLE-NISSEI DALLAS COMPANY, a 
                                  joint venture
                                  
                                  
                                  
                                  By:                                          
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                                  Title:                                       
                                        ---------------------------------------
                                  
                                  Date:                                        
                                       ----------------------------------------





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