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                                                                   Exhibit 10.51

                                THIRD AMENDMENT
                                     TO THE
                      FISHER SCIENTIFIC INTERNATIONAL INC.
                         SAVINGS AND PROFIT SHARING PLAN

      WHEREAS, Fisher Scientific International Inc. desires to amend the Fisher
Scientific International Inc. Savings and Profit Sharing Plan (the "Plan") to
provide for immediate eligibility to participate in the Plan and to increase the
amount of Before-Tax Contributions and After-Tax Contributions a Participant may
elect to contribute to the Plan to 50% of the Participant's Compensation; and

      WHEREAS, Section 11.1 of the Plan grants the Administrative and Investment
Committee (the "Committee") the authority to make amendments to the Plan which
will not involve an estimated annual cost under the Plan in excess of $500,000;

      NOW,THEREFORE, it hereby is:

      RESOLVED THAT the Plan be hereby amended as follows:

1.    Section 1.21 of the Plan is amended and restated effective January 1, 2003
      as follows:

      "1.21. Eligibility Service means the completion by an Employee of an Hour
      of Service.

2.    Section 3.1(a), (b) and (c) of the Plan is hereby amended and restated
      effective as of January 1, 2003 as follows:

      "3.1 Employee Contributions:

      (a) Before-Tax Contributions. A Participant may elect to make Before-Tax
      Contributions on a form provided by the Committee. A Participant may elect
      a deferral of cash Compensation otherwise payable to such Participant, in
      a whole percentage selected by the Participant which may not be less than
      1% of Compensation and which may not exceed the lesser of (i) 50% of
      Compensation, or (ii) $11,000 (adjusted from time to time for increases in
      the cost-of-living made pursuant to Code Section 402(g)(5)) ("Section
      402(g) limit").

      (b) After-Tax Contributions. A Participant may elect to make After-Tax
      Contributions on a form provided by the Committee. A Participant may
      contribute cash Compensation otherwise payable to such Participant, in a
      whole percentage selected by the Participant which may not be less than 1%
      of Compensation and which may not exceed 50% of Compensation.

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      (c) Aggregate Limit on Before-Tax and After-Tax Contributions. In addition
      to the limitations described in paragraphs (a) and (b), the total amount
      of Before-Tax and After-Tax Contributions shall not exceed 50% of
      Compensation. Also, the Committee may limit the Before-Tax and After-Tax
      Contributions of Highly Compensated Employees in any manner under rules
      uniformly applied to all Highly Compensated Employees."

      IN WITNESS WHEREOF, the Fisher Scientific International Inc. Savings and
Profit Sharing Plan is amended the 10 day of December, 2002.

                                        ADMINISTRATIVE AND INVESTMENT COMMITTEE

                                        /s/ Paul M. Meister
                                        ------------------------------------
                                        Paul M. Meister

                                        /s/ Todd M. DuChene
                                        ------------------------------------
                                        Todd M. DuChene<PAGE>
                                                                   Exhibit 10.52

                                FOURTH AMENDMENT
                                     TO THE
                      FISHER SCIENTIFIC INTERNATIONAL INC.
                         SAVINGS AND PROFIT SHARING PLAN

      WHEREAS, Fisher Scientific International Inc. desires to amend the Fisher
Scientific International Inc. Savings and Profit Sharing Plan (the "Plan") to
include FSI Receivables Corporation and Medical Analysis Systems, Inc. as
participating companies in the Plan; and

      WHEREAS, Section 11.1 of the Plan grants the Administrative and Investment
Committee (the "Committee") the authority to make amendments to the Plan which
will not involve an estimated annual cost under the Plan in excess of $500,000;

      NOW,THEREFORE, it hereby is:

      RESOLVED THAT the Plan be hereby amended as follows:

1. Schedule I of the Plan is amended effective January 1, 2003, to include in
the list of Participating Companies the following:

      "FSI Receivables Corporation, effective January 1, 2003"

2. Schedule I of the Plan is amended effective January 1, 2003, to include in
the list of Participating Companies the following:

      "Medical Analysis Systems, Inc., effective January 1, 2003"

      IN WITNESS WHEREOF, the Fisher Scientific International Inc. Savings and
Profit Sharing Plan is amended the 20 day of December, 2002.

                                        ADMINISTRATIVE AND INVESTMENT COMMITTEE

                                        /s/ Paul M. Meister
                                        ------------------------------------
                                        Paul M. Meister

                                        /s/ Todd M. DuChene
                                        ------------------------------------
                                        Todd M. DuChene<PAGE>
                                                                   Exhibit 10.53

                                 FIFTH AMENDMENT
                                     TO THE
                      FISHER SCIENTIFIC INTERNATIONAL INC.
                         SAVINGS AND PROFIT SHARING PLAN

      WHEREAS, Fisher Scientific International Inc. (the "Company") desires to
merge the Fisher Scientific Company L.L.C. Profit Sharing Plan (the "SEC Plan")
into the Fisher Scientific International Inc. Savings and Profit Sharing Plan
(the "Plan"); and

      WHEREAS, the Company desires to preserve certain rights and protected
benefits available under the SEC Plan; and

      WHEREAS, Section 11.1 of the Plan grants the Administrative and Investment
Committee (the "Committee") the authority to make amendments to the Plan which
will not involve an estimated annual cost under the Plan in excess of $500,000.

      NOW,THEREFORE, it hereby is:

      RESOLVED THAT effective January 1, 2003, the SEC Plan is merged into the
Plan and the Plan is hereby amended as follows:

      This Schedule J is to be added to the Plan effective January 1, 2003, for
purposes of preserving the following rights, protected benefits and automatic
forms of distribution previously available under the SEC Plan for such
Participants.

                                   "Schedule J

      This Schedule J shall apply to any individual, who was a participant in
the Fisher Scientific Company L.L.C. Profit Sharing Plan (the "SEC Plan and such
account thereunder, the "SEC Transfer Account") and as a result of the merger,
has a plan to plan transfer to this Plan of their SEC Transfer Account. Only
with respect to such Participant's interests in his or her SEC Transfer Account,
a former SEC Plan Participant shall be entitled to the following rights,
protected benefits and automatic forms of distribution:

      1. Vesting. A former SEC Plan Participant shall become fully vested with
respect to such Participant's entire SEC Transfer Account.

      2. Loans. If a former SEC Plan Participant uses his Vested Account as
security for a loan, such Participant must obtain consent from his spouse, if
any, pursuant to the terms of the SEC Plan, no earlier than the beginning of the
90-day period that ends on the date on which the loan to be secured is made.

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      3. A former SEC Plan Participant shall be entitled to elect to receive his
or her interest in their SEC Transfer Account in the optional forms of
distribution available pursuant to the terms of the SEC Plan until the earlier
of (i) the 90th day following the date such Participant receives the furnished
summary of material modification of the amendment to the SEC Plan which reduces
the optional forms of distribution available under the SEC Plan, or (ii) the
first day of the second plan year in which such amendment is adopted.

      4. Only with respect to a former SEC Plan Participant's interest in their
SEC Transfer Account, a Participant, who as of January 1, 2003, has a spouse
shall have the automatic forms of distribution available as follows:

      (a) Retirement Benefits. The automatic form of retirement benefit for a
former SEC Plan Participant who does not die before the Annuity Starting Date
shall be the Qualified Joint and Survivor Annuity and an election of any
optional forms of distribution must comply with Section 417(a) of the Code.

      (b) Death Benefits. The automatic form of death benefits for a former SEC
Plan Participant who dies before his Annuity Starting Date shall be a Qualified
Preretirement Survivor Annuity, so long as such Participant has been
continuously married throughout the one-year period ending on the date of his
death and an election of any optional forms of distribution must comply with
Section 417(a) of the Code. The spouse may elect to start receiving the death
benefit on any first day of the month on or after such Participant dies and by
the date such Participant would have been 70 1/2. If the spouse dies before the
benefits start, the former SEC Plan Participant's Vested Account, determined as
of the date of the spouse's death, shall be paid to the spouse's beneficiary as
defined under the Plan.

      5. All terms not herein defined shall have the same meaning assigned to
them under the SEC Plan.

      IN WITNESS WHEREOF, the Fisher Scientific International Inc. Savings and
Profit Sharing Plan is amended the 20 day of December, 2002.

                                        ADMINISTRATIVE AND INVESTMENT COMMITTEE

                                        /s/ Paul M. Meister
                                        ------------------------------------
                                        Paul M. Meister

                                        /s/ Todd M. DuChene
                                        ------------------------------------
                                        Todd M. DuChene

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