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                                                                      EXHIBIT 28

                            GAMMA BIOLOGICALS, INC.


                        1995 EMPLOYEE STOCK OPTION PLAN


                                   ARTICLE I
                                   ---------

                                    PURPOSE

     Gamma Biologicals, Inc. (the "Company") is largely dependent for the
successful conduct of its business on the initiative, effort and judgment of its
officers and employees and the officers and employees of its subsidiaries.  The
Company's 1995 Employee Stock Option Plan (the "Plan") is intended to provide
the officers and the key employees of the Company and its subsidiaries an
incentive through stock ownership in the Company and encourage them to remain in
the Company's employ.  Moreover, since the stock options provided for in the
Plan are subject to various alternative provisions of the Internal Revenue Code
of 1986, as amended (the "Code"), the Committee will have certain flexibility in
shaping options granted under the Plan to the particular circumstances of the
optionee, thus recognizing the full value of the stock option.


                                   ARTICLE II
                                   ----------

                                 ADMINISTRATION

     The Plan shall be administered by the Stock Option Committee (the
"Committee"), which shall at all times consist of not less than two members of
the Board of Directors of the Company (the "Board"), and shall not include any
persons that are not members of the Board.  All members of the Committee shall
be selected by (and serve at the pleasure of) the Board.  All members of the
Committee shall be "disinterested persons" within the meaning of Rule 16b-3 of
the General Rules and Regulations under the Securities Exchange Act of 1934, as
amended (the "1934 Act").  Subject to the express provisions of the Plan and the
policies of each stock exchange or national automated quotation system on which
any of the Company's stock at any time may be listed or quoted, the Committee
shall have plenary authority, in its discretion, to recommend to the Board the
individuals within the class set forth in Article IV to whom, and the time and
price per share at which, stock options shall be granted, the number of shares
to be subject to each stock option and the other terms and provisions of their
respective Agreements, as defined herein (which need not be identical).  In
making such recommendations and determinations, the Committee may take into
account the nature of the services rendered by the respective employees, their
present and potential contributions to the Company's success and such other
factors as the Committee in its discretion shall deem relevant.

     Subject to the express provisions of the Plan, the Committee shall also
have plenary authority (i) to interpret the Plan, (ii) to prescribe, amend and
rescind rules and regulations

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regulating it, (iii) to recommend to the Board the terms and provisions of the
respective stock options (which need not be identical), (iv) to determine the
duration and purposes of leaves of absence that may be granted to participants
without constituting a termination of their employment for purposes of the Plan,
(v) to accelerate or extend the exercisability or vesting of any or all stock
options, and (vi) to make all other determinations necessary or advisable for
the administration of the Plan.  The Committee shall hold meetings at such time
and places as it may determine.  Acts by the majority of the Committee or acts
reduced to or approved in writing by a majority of the members of the Committee
shall be the valid acts of the Committee.  From time to time the Board may
increase the size of the Committee and appoint additional members thereof,
remove members (with or without cause), and appoint new members in substitution
therefor, or fill vacancies however caused, subject to the requirements that the
members of the Committee shall be "disinterested persons" as described above and
that there always be at least two members of the Committee.  The Committee's
determination on the matters referred to in this Plan shall be final, conclusive
and binding upon all optionees.


                                  ARTICLE III
                                  -----------

                  SHARES SUBJECT TO PLAN AND DURATION OF PLAN

     Under the Plan the Board may, but only upon recommendation of the
Committee, grant to eligible persons incentive stock options (as defined in the
Code) and/or non-qualified stock options to purchase up to but not exceeding an
aggregate amount of 250,000 shares of the Company's $0.10 par value Common Stock
("Common Stock") (subject to adjustment as provided in Article VIII).  Shares
subject to stock options under the Plan may be either authorized and unissued
shares or issued shares that have been acquired by the Company and are being
held in its treasury, in the sole discretion of the Board.  When stock options
have been granted under the Plan and have lapsed unexercised or partially
unexercised or have been surrendered for cancellation by the optionee thereof,
the shares which were subject thereto may be reoptioned under the Plan.  The
maximum number of shares of Common Stock that may be delivered pursuant to stock
options to any employee under this Plan shall not exceed 100,000 (subject to
adjustment as provided in Article VIII).  No stock options shall be granted more
than 10 years after the effective date of the Plan.


                                   ARTICLE IV
                                   ----------

                         ELIGIBILITY AND PARTICIPATION

     To the fullest extent permitted by applicable securities laws, all officers
and employees of the Company, any Parent Corporation, any Subsidiary Corporation
(including, without limitation, Parent Corporations or Subsidiary Corporations
which become such after adoption of the Plan) and their respective divisions
shall be eligible to receive stock options under the Plan, and employment by any
of such Parent Corporations and Subsidiary Corporations shall constitute
employment by the Company for purposes of this Plan; provided, however, that no
member of the Committee shall be entitled to receive a stock option under this
Plan while

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serving as a member of the Committee.  Directors of the Company who are not
regular employees of the Company are not eligible to participate in the Plan.
For purposes of the Plan, the term "Parent Corporation" shall have the meaning
set forth in Section 424(e) of the Code, and the term "Subsidiary Corporation"
shall have the meaning set forth in Section 424(f) of the Code.


                                   ARTICLE V
                                   ---------

                     TERMS AND CONDITIONS OF STOCK OPTIONS

     Each stock option granted under the Plan shall be evidenced by a stock
option agreement (the "Agreement"), the form of which shall have been approved
by the Committee.  The Agreement shall be executed by the Company and the
optionee and shall set forth the terms and conditions of the stock option, which
terms and conditions shall include, but not be limited to, the following:

          (a) Option Price.  The option price shall be determined by the
     Committee, but shall not in any event be less than the par value of the
     Common Stock.

          (b) Term of Stock Option.  The term of the stock option shall be
     selected by the Committee, but in no event shall such term exceed ten (10)
     years from the date such option is granted.  Each such stock option shall
     be subject to earlier termination as hereinafter provided.

          (c) Transferability.  Stock options granted hereunder shall not be
     transferable other than by will or operation of the laws of descent and
     distribution or pursuant to a qualified domestic relations order as defined
     in the Code or Title I of the Employee Retirement Income Security Act of
     1974, as amended, or the rules thereunder.  During the lifetime of the
     optionee, stock options granted hereunder shall be exercisable only by the
     optionee, or the optionee's guardian or legal representative.

          (d) Vesting.  The Committee shall have complete discretion in
     determining when stock options granted hereunder are to vest; provided,
     however, that the sale of the shares of Common Stock issued upon the
     exercise of the stock option by any person subject to Section 16 of the
     1934 Act shall not be allowed until at least six months after the grant of
     the stock option.  Such vesting determination for each stock option is to
     be made prior to or at the time that stock option is granted.

          (e) Termination of Employment.  In the event of an optionee's
     termination of employment with the Company for any reason other than death,
     all stock options granted hereunder shall thereupon terminate.  Upon the
     termination of an optionee's employment by reason of his death, his stock
     option shall terminate to the extent it was not exercisable at the date of
     optionee's death, but to the extent it was then exercisable by the
     optionee, the optionee's estate or the beneficiaries thereof shall be
     entitled to exercise such options for a period of one (1) year from the
     date of the optionee's death but not

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     thereafter.  Notwithstanding any other provisions of this subparagraph (e),
     no stock option shall be exercised after the expiration of ten (10) years
     from the date such option is granted.

          (f) Other Conditions.  At its sole discretion, the Committee may
     impose other conditions upon the stock options granted hereunder, so long
     as those conditions do not conflict with any other provisions of the Plan.
     Such conditions may include, by way of illustration, but not by way of
     limitation, percentage limitations upon the exercisability of stock options
     granted hereunder.


                                   ARTICLE VI
                                   ----------

                            INCENTIVE STOCK OPTIONS

     The Committee and the Board, in recommending and granting stock options
hereunder, shall have the discretion to determine that certain options shall be
Incentive Stock Options, as defined in Section 422 of the Code, while other
options shall be Non-Qualified Stock Options.  Neither the members of the
Committee, the members of the Board nor the Company shall be under any
obligation or incur any liability to any person by reason of the determination
by the Committee or the Board whether an option granted under the Plan shall be
an Incentive Stock Option or a Non-Qualified Stock Option.  The provisions of
this Article VI shall be applicable to all Incentive Stock Options at any time
granted or outstanding under the Plan.

     All Incentive Stock Options granted or outstanding under the Plan shall be
granted and held subject to and in compliance with the terms and conditions
specifically set forth in Articles II, III, IV, and V hereof and, in addition,
subject to and in compliance with the following further terms and conditions:

          (a) the per share option price of all Incentive Stock Options shall
     not be less than one hundred percent (100%) of the Fair Market Value (as
     defined below) of one share of the Company's Common Stock at the time the
     option is granted (notwithstanding any provision of Article V hereof to the
     contrary);

          (b) no Incentive Stock Option shall be granted to any person who, at
     the time of the grant, owns stock possessing more than ten percent (10%) of
     the total combined voting power of all classes of stock of the Company or
     any Parent Corporation or Subsidiary Corporation of the Company; provided,
     however, that this ownership limitation will be waived if at the time the
     option is granted the per share option price is at least one hundred ten
     percent (110%) of the Fair Market Value of one share of the Company's
     Common Stock and such option by its terms is not exercisable after the
     expiration of five (5) years from the date such option is granted;

          (c) an Incentive Stock Option shall not be transferable other than by
     will or the laws of descent and distribution, and shall be exercisable
     during the lifetime of the optionee only by the optionee; and

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          (d) the aggregate Fair Market Value of all shares of Common Stock
     (determined at the time of the grant of the option) with respect to which
     Incentive Stock Options are exercisable for the first time by any optionee
     during any one calendar year shall not exceed $100,000.

     For purposes of the Plan, the term "Fair Market Value" on any date shall
mean (i) if the Common Stock is listed or admitted to trade on a national
securities exchange or national market system, the closing price of the Common
Stock, as published in the Wall Street Journal, so listed or admitted to trade
on such date or, if there is no trading of the Common Stock on such date, then
the closing price of the Common Stock on the next preceding date on which there
was trading in such shares; (ii) if the Common Stock is not listed or admitted
to trade on a national securities exchange or national market system, the mean
between the bid and asked price for the Common Stock on such date, as furnished
by the National Association of Securities Dealers, Inc. through NASDAQ or a
similar organization if NASDAQ is no longer reporting such information; or (iii)
if the Common Stock is not listed or admitted to trade on a national securities
exchange and if bid and asked prices for the Common Stock are not so furnished
through NASDAQ or a similar organization, the value established by the Committee
for purposes of granting stock options under the Plan.  In addition to the above
rules, Fair Market Value shall be determined without regard to any restriction
other than a restriction which, by its terms, will never lapse.


                                  ARTICLE VII
                                  -----------

                           EXERCISE OF STOCK OPTIONS

     Stock options granted hereunder may be exercised in whole or in part at any
time or from time to time during their respective terms, but only to the extent
that they have vested and only by tendering to the Company written notice of
exercise accompanied by the aggregate purchase price for the shares with respect
to which the stock option is being exercised.  The purchase price of shares of
Common Stock of the Company acquired upon the exercise of any stock option
granted under the Plan may be paid by an optionee by the payment of cash or
check, or, upon receipt of all required regulatory approvals, if any, by the
assignment to the Company of shares of the Company's Common Stock theretofore
owned by the optionee having a Fair Market Value equal to such option price, or
by any combination thereof.

     No stock option shall be exercisable unless the Plan and all shares
issuable on the exercise thereof have been registered under the Act and all
other applicable securities laws, and there is available for delivery a
prospectus meeting the requirements of Section 10 of the Securities Act of 1933,
as amended (the "1933 Act"), or the Company shall have first received the
opinion of its counsel that registration under the 1933 Act and all other
applicable securities laws is not required in connection with such issuance.
At the time of exercise, if the shares with respect to which the stock option is
being exercised have not been registered under the 1933 Act and all other
applicable securities laws, the Company may require the optionee to give the
Company whatever written assurance counsel for the Company may require that the
shares are being acquired for investment and not with a view to the distribution
thereof, and that the shares

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will not be disposed of without the written opinion of such counsel that
registration under the 1933 Act and all other applicable securities laws is not
required.  Share certificates issued to the optionee upon exercise of the stock
option shall bear a legend to the foregoing effect to the extent counsel for the
Company deems it advisable.

     In the event that the Company is required to withhold payroll or other
federal or state taxes upon the grant or exercise of any non-qualified stock
option granted pursuant to this Plan, then upon the exercise of any such stock
option, the Company shall be entitled to withhold that number of shares
otherwise deliverable upon the exercise of the stock option as it may be
required to so withhold in order to satisfy its obligations under applicable tax
laws.  The Company shall also have the right to withhold from the cash
compensation otherwise payable by the Company or any subsidiary to the optionee
any amount necessary to satisfy its payroll or other tax withholding
obligations.  The Company may also require, as a condition to exercise of any
non-qualified stock option granted under this Plan, the payment by the optionee
to the Company by cash or check of the amount of any taxes which are required to
be withheld by the Company upon the exercise of the option.


                                  ARTICLE VIII
                                  ------------

                                  ADJUSTMENTS

          (a) Adjustments Upon Changes in Capitalization.  Subject to any
     required action by the Company's directors and shareholders, the number of
     shares provided for in each outstanding stock option and the price per
     share thereof, and the number of shares provided for in the Plan, shall be
     proportionately adjusted for any increase or decrease in the number of
     issued shares of the Company's Common Stock resulting from a subdivision or
     consolidation of shares or the payment of a stock dividend (but only on the
     Common Stock), a stock split, a reverse stock split, or any other increase
     or decrease in the number of such shares effected without receipt of
     consideration by the Company, and shall also be proportionately adjusted in
     the event of a spin-off, spin-out, or other distribution of assets to
     shareholders of the Company, to the extent necessary to prevent dilution of
     the interests of grantees pursuant to the Plan or of the other shareholders
     of the Company, as applicable.  If the Company shall engage in a merger,
     consolidation, reorganization or recapitalization, each outstanding stock
     option (or if such transaction involves less than all of the shares of the
     Company's Common Stock, then a number of stock options proportionate to the
     number of such involved shares), shall become exercisable for the
     securities and other consideration to which a holder of the number of
     shares of the Company's Common Stock subject to each such stock option
     would have been entitled to receive in any such merger, consolidation,
     reorganization or recapitalization.

          (b) Acceleration.  In the event of a potential merger or consolidation
     involving the Company (regardless of whether the Company is the surviving
     entity of such merger or consolidation), a potential liquidation or
     dissolution of the Company, a potential sale or other disposition by the
     Company of all or substantially all of its assets, or a potential

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     sale or other disposition by the shareholders of the Company of all or
     substantially all of the outstanding Common Stock to one purchaser (any
     such merger, consolidation, liquidation, dissolution, or sale being
     referred to herein as a "Significant Event"), then the Company shall have
     the option of terminating all outstanding stock options upon the actual
     occurrence of the Significant Event, by notice to all optionees at least 15
     days before the occurrence of the Significant Event.  In consideration for
     this option of the Company to terminate outstanding stock options, the
     Company, if it exercises its option, shall waive any and all restrictions
     on the vesting of optionees' rights under stock options granted pursuant to
     this Plan, and optionees' rights under their respective stock options shall
     vest in full, subject to the actual occurrence of the Significant Event.
     Any exercise by an optionee in these circumstances may be conditioned upon
     the occurrence of the Significant Event.  If the Company exercises its
     option under this paragraph (b), upon the actual occurrence of the
     Significant Event each outstanding stock option shall terminate.  If the
     potential Significant Event does not in fact occur for any reason, then the
     Company's exercise of its option under this paragraph (b) shall have no
     effect and the optionee's rights will be vested only to the extent that
     they would be vested if the Company had never exercised its option under
     this paragraph (b).  Notwithstanding any other provision of this Plan to
     the contrary, with regard to any and all optionees subject to Section 16 of
     the 1934 Act, if the Company exercises its option herein, the stock options
     held by such optionees shall terminate as set forth above, provided,
     however, that vesting of any such optionee's rights under such stock
     options shall not be accelerated without the prior consent of such
     optionee.

          (c) Change of Par Value.  In the event of a change in the Company's
     Common Stock which is limited to a change of all of its authorized shares
     with par value into the same number of shares with a different par value or
     without par value, the shares resulting from any such change shall be
     deemed to be Common Stock within the meaning of the Plan.

          (d) Miscellaneous.  The adjustments provided for in this Article shall
     be made by the Committee, whose determination in that respect shall be
     final, binding and conclusive.  Except as hereinbefore expressly provided
     in this Article, the holder of a stock option shall not be entitled to the
     privilege of stock ownership as to any shares of Common Stock  or other
     stock not actually issued and delivered to the holder.  Any issue by the
     Company of shares of stock of any class, or securities convertible into
     shares of stock of any class, shall not affect and no adjustment by reason
     thereof shall be made with respect to the number or price of shares of the
     Company's Common Stock subject to any stock option.  The grant of a stock
     option pursuant to the Plan shall not affect in any way the right or power
     of the Company to, among other things, make adjustments, reclassifications,
     reorganizations or changes of its capital or business structure or to merge
     or to consolidate or to dissolve or liquidate or sell or transfer all or
     any part of its business or assets.

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                                 ARTICLE IX
                                 ----------

                         ISSUANCE OF STOCK CERTIFICATES

          Upon exercise of a stock option, the person exercising the stock
option shall be entitled to one (1) stock certificate evidencing the shares
acquired upon such exercise; provided, however, that any person who tenders
Common Stock of the Company in payment of a portion or all of the purchase price
of Common Stock purchased upon exercise of the stock option shall be entitled to
receive a separate certificate representing the number of shares purchased in
consideration of the tender of such Common Stock.


                                   ARTICLE X
                                   ---------

                           CONTINUATION OF EMPLOYMENT

          Nothing contained in the Plan (or in any stock option granted pursuant
to the Plan) shall confer upon any employee any right to continue in the employ
of the Company or any Parent Corporation or Subsidiary Corporation or constitute
any contract or agreement of employment or interfere in any way with the right
of the Company, the Parent Corporation or any Subsidiary Corporation to reduce
any person's compensation from the rate in existence at the time of the granting
of a stock option or to terminate such person's employment.  Nothing contained
herein or in any Agreement shall affect any other contractual rights of an
employee.


                                   ARTICLE XI
                                   ----------

                          AMENDMENT OR DISCONTINUANCE

          The Board of the Company may at any time and from time to time amend,
rescind, suspend or terminate the Plan, as it shall deem advisable, provided
that the Plan may not be amended in any manner which would cause the Plan to no
longer comply with Rule 16b-3 of the General Rules and Regulations under the
1934 Act, or any successor rule, or the provisions of the Code applicable to
Incentive Stock Options, as such rule or provisions shall read as of the time of
amendment.  In addition to Board approval of any amendment to the Plan, if Rule
16b-3 of the General Rules and Regulations under the 1934 Act, or any successor
rule, or the provisions of the Code applicable to Incentive Stock Options, as
such rule or provisions shall read as of the time of amendment, requires
shareholder approval of such amendment, then such amendment shall be approved by
the holders of a majority of the voting stock of the Company (voting as a single
class) present, or represented, and entitled to vote at a meeting of such
shareholders duly held in accordance with the applicable laws of the state or
other jurisdiction in which the Company is incorporated.

          In addition, no change may be made in, and no amendment, rescission,
suspension or termination of the Plan shall have an effect on, stock options
previously granted under the Plan

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which may impair or alter the rights or obligations of the holders thereof,
except that any change may be made in stock options previously granted with the
consent of the optionees.


                                  ARTICLE XII
                                  -----------

                                 MISCELLANEOUS

          (a) Governing Law.  The Plan and the stock options issued hereunder
     shall be governed by, and construed and enforced in accordance with, the
     laws of the State of Texas applicable to contracts made and performed
     within that State.

          (b) No Liability for Good Faith Determinations.  Neither the members
     of the Board nor any member of the Committee shall be liable for any act,
     omission or determination taken or made in good faith with respect to the
     Plan or any stock option granted under it.  All Board and Committee members
     shall also be entitled, with respect to all matters relating to the Plan,
     to all of the protections and rights, including without limitation
     indemnification and limitation of liability rights, provided to Board
     members generally pursuant to applicable law, the Articles of Incorporation
     of the Company, the Bylaws of the Company or otherwise.

          (c) Information Confidential.  As partial consideration for the
     granting of each stock option hereunder and subject to the provisions of
     applicable law, the optionee shall keep confidential the manner and amount
     of his participation in the Plan; provided, however, that such information
     may be given in confidence to a financial institution to the extent that
     such information is necessary in order to secure a loan for the exercise of
     any stock options granted to such optionee.  In the event any breach of
     this promise comes to the attention of the Committee, and in addition to
     any other rights and remedies of the Company or the Board against such
     optionee, in determining whether to recommend the grant of any future stock
     option to such optionee, the Committee shall take into consideration such
     breach  as a factor militating against the advisability of granting any
     future stock option to such employee.

          (d) Other Benefits.  Participation in the Plan shall not preclude the
     optionee from eligibility in any other stock option plan of the Company,
     its Parent Corporation or any Subsidiary Corporation or any benefit,
     insurance, pension, profit sharing, retirement, bonus or other extra
     compensation plans that the Company, its Parent Corporation or any
     Subsidiary Corporation has adopted, or may, at any time, adopt for the
     benefit of its employees.

          (e) Execution of Receipts and Releases.  Any issuance or transfer of
     shares of Common Stock to the optionee, or to his legal representative,
     heir, legatee or distributee, in accordance with the provisions hereof,
     shall, to the extent thereof, be in full satisfaction of all claims of such
     persons hereunder.  The Board may require any optionee, legal
     representative, heir, legatee or distributee, as a condition precedent to

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     such issuance or transfer, to execute a release and receipt therefor in
     such form as it shall determine.

          (f) Company Records.  Records of the Company, the Parent Corporation
     or any Subsidiary Corporation regarding the optionee's period of
     employment, termination of employment and the reason therefor, leaves of
     absence, re-employment and other matters shall be conclusive for all
     purposes hereunder, unless determined by the Committee in its sole
     discretion to be incorrect.

          (g) Information.  The Company, the Parent Corporation and any
     Subsidiary Corporation shall, upon request or as may be specifically
     required hereunder, furnish or cause to be furnished to the Committee all
     of the information or documentation that is necessary or required by the
     Committee or the Board to perform their respective duties and functions
     under the Plan.

          (h) No Liability of Company.  The Company assumes no obligation or
     responsibility to the optionee or his legal representatives, heirs,
     legatees or distributees for any act of, or failure to act by, the
     Committee or the Board.

          (i) Severability.  In the event any provision of the Plan shall be
     held to be illegal or invalid for any reason, the illegality or invalidity
     shall not affect the remaining provisions hereof, but shall be fully
     severable and the Plan shall be construed and enforced as if the illegal or
     invalid provision had never been included herein.

          (j) Notice.  Whenever any notice is required or permitted hereunder,
     such notice must be in writing and personally delivered or sent by mail.
     Any notice required or permitted to be delivered hereunder shall be deemed
     to be delivered on the date that it is personally delivered or, whether
     actually received or not, on the third business day after it is deposited
     in the United States mail, certified or registered, postage prepaid,
     addressed to the person who is to receive it at the address which such
     person has theretofore specified by written notice delivered in accordance
     herewith.  The Company or an optionee may change, at any time and from time
     to time, by written notice to the other, the address which it or he had
     theretofore specified for receiving notices.  Until it is changed in
     accordance herewith, the Company and each optionee shall specify as its and
     his address for receiving notices the address set forth in the Agreement
     pertaining to the shares to which such notice relates.

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                                 ARTICLE XIII
                                 ------------

                              SHAREHOLDER APPROVAL

          The Plan shall be effective as of the date when it is approved by the
holders of a majority of the outstanding voting stock of the Company (voting as
a single class) present, or represented, and entitled to vote at a meeting of
such shareholders duly held in accordance with the applicable laws of the state
or other jurisdiction in which the Company is incorporated.

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