State of Delaware
                                                        Secretary of State
                                                     Division of Corporations
                                                   Delivered 04:29 PM 01/05/2006
                                                     FILED 04:03 PM 01/05/2006
                                                   SRV 060012446 - 4089721 FILE

                          CERTIFICATE OF INCORPORATION
                                       OF
                          ANCILLARY CARE SERVICES, INC.

      I, the undersigned, for the purpose of incorporating and organizing a
corporation under the General Corporation Law of the State of Delaware, do
execute this Certificate of Incorporation and do hereby certify as follows:

                                    ARTICLE I

      The name of the corporation is Ancillary Care Services, Inc.

                                   ARTICLE II

      The address of its registered office is the State of Delaware is
Corporation Trust Center, 1209 Orange Street, City of Wilmington, County of New
Castle, Delaware 19801. The name of its registered agent at such address is The
Corporation Trust Company.

                                   ARTICLE III

      The purpose of the corporation is to engage in any lawful act or activity
for which corporation may be organized under the General Corporation Law of the
State of Delaware.

                                   ARTICLE IV

      The total number of shares of stock which the corporation shall have
authority to issue is 1,000 shares of common stock, par value of $.01 per share.

                                    ARTICLE V

      The incorporator of the corporation is Van M. Jolas, whose mailing address
is Locke Liddell & Sapp LLP, 2200 Ross Avenue, Suite 2200, Dallas, Texas 75201.

                                   ARTICLE VI

      The powers of the incorporator are to terminate upon the filing of this
Certificate of Incorporation. The names and mailing addresses of the persons who
are to serve as the initial directors of the corporation until the first annual
meeting of stockholders of the corporation, or until their successors are
elected and qualified, are:

                Name                                Address
                ----                                -------
        Wayne Shellhammer               8080 Tristar Drive, Suite 100
                                             Irving, TX 75063

        David Boone                     8080 Tristar Drive, Suite 100
                                             Irving, TX 75063

<PAGE>

                                   ARTICLE VII

      The election of directors of the corporation need not be by written
ballot.

                                  ARTICLE VIII

      The board of directors shall have the power to adopt, amend or repeal
bylaws. Such power conferred upon the board of directors shall not divest or
limit the stockholders' power to adopt, amend or repeal bylaws.

                                   ARTICLE IX

      A director of the corporation shall not be liable to the corporation or
its stockholders for monetary damages for breach of fiduciary duty as a
director, except to the extent such exemption from liability or limitation
thereof is not permitted under the General Corporation Law of the State of
Delaware as the same exists or may hereafter be amended. Any amendment,
modification or repeal of the foregoing sentence shall not adversely affect any
right or protection of a director of the corporation hereunder in respect of any
act or omission occurring prior to the time of such amendment, modification or
repeal.

                            [Signature Page Follows]


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<PAGE>

      The undersigned incorporator hereby acknowledges that the foregoing
Certificate of Incorporation is his/her act and deed on this 5th day of January,
2006.


                                               /s/ Van M. Jolas
                                               ---------------------------------
                                               Van M. Jolas, Incorporator


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