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                                                                   EXHIBIT 10.27

                         FIRST AMENDMENT TO AMENDED AND
                       RESTATED REPLACEMENT LOAN AGREEMENT

         THIS FIRST AMENDMENT TO AMENDED AND RESTATED REPLACEMENT LOAN AGREEMENT
(the "Agreement") is made this ___ day of April 1998, by and among BIORELIANCE
CORPORATION, a corporation organized and in good standing under the laws of the
State of Delaware, successor in interest to Microbiological Associates, Inc.
(the "Company"), MA BIOSERVICES, INC., a corporation organized and in good
standing under the laws of the State of Delaware ("MA BioServices"), MAGENTA
CORPORATION, a corporation organized and in good standing under the laws of the
State of Delaware ("Magenta") and MAGENTA VIRAL PRODUCTION, INC., a corporation
organized and in good standing under the laws of the State of Delaware ("Magenta
Viral"; together with the Company, MA BioServices and Magenta, each a "Borrower"
and collectively, the "Borrowers") and NATIONSBANK, N.A., successor in interest
to Maryland National Bank, each a national banking association, its successors
and assigns, (the "Lender").

                                    RECITALS

         A. The Borrowers and the Lender are parties to a certain Amended and
Restated Replacement Loan Agreement dated as of October 31, 1997 (the "Loan
Agreement"), pursuant to which the Lender has agreed to make available to the
Borrowers certain loans as more fully described therein. Unless otherwise
defined herein, all capitalized terms used herein shall have the meanings given
to such terms in the Loan Agreement.

         B. At the request of the Company, the Lender is making a term loan in
the original principal amount of Four Million Six Hundred Fifty Thousand Dollars
($4,650,000) (the "BPG Term Loan") to BPG Industrial Partners II LLC, a Maryland
limited liability company ("BPG"). The proceeds of the BPG Term Loan are being
used to finance the construction of a shell building and mezzanine, containing
58,733 square feet of space, more or less, certain systems in the building
shell, and the parking lot, sidewalks, driveways and landscaping to be occupied
by Magenta. The Company has agreed to guaranty repayment of the BPG Loan
pursuant to that certain Guaranty of Payment of even date herewith from the
Company in favor of the Lender (together with all amendments, modifications,
replacements and substitutions, the "BPG Guaranty").

         C. The Borrowers have requested and the Lender has agreed to modify
certain provisions of the Loan Agreement as hereinafter set forth.

                                   AGREEMENTS

         NOW, THEREFORE, in consideration of the premises, the mutual agreements
herein contained, and other good and valuable consideration, the receipt and
sufficiency of which are 
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hereby acknowledged, the Borrowers and the Lender hereby agree that the Loan
Agreement is hereby modified as follows:

         1. Recitals. The parties hereto acknowledge and agree that the above
Recitals are true and correct in all respect and that the same are incorporated
herein and made a part hereof by reference.

         2. Definitions The definition of "Loan Documents" as set forth in
Section I of the Loan Agreement is hereby amended to include the BPG Guaranty.

         3. Financial Statements. Section 5.1 (b) of the Loan Agreement is
hereby deleted in its entirety.

         4. Tangible Net Worth. Section 5.2 of the Loan Agreement is hereby
deleted in its entirety.

         5. Funded Debt to EBITDA. Section 5.3 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 5.3 Funded Debt to EBITDA. Maintain a ratio of Funded
         Debt to EBITDA not greater than 3.5 to 1.0 as of the end of each fiscal
         quarter, based on the four (4) quarter period ending on such date. For
         purposes hereof, "Funded Debt" shall mean all bank indebtedness
         (secured and unsecured), plus all capitalized lease obligations,
         subordinated debt and any other similar liabilities and contingent
         liabilities reported in financial statements of the Company and its
         affiliates as direct or contingent liabilities. For purposes hereof,
         "EBITDA" shall mean earnings before interest, taxes, depreciation and
         amortization, all as determined in accordance with GAAP and all as
         determined on a consolidated basis for the twelve (12) month period
         then ending.

         6. Profitability. Section 5.4 of the Loan Agreement is hereby deleted
in its entirety and the following is inserted in full substitution thereof:

                  Section 5.4 Profitability. The Borrowers will not as of the
         end of each fiscal year, on a consolidated basis have any Operating
         Losses. For purposes hereof, "Operating Losses" shall mean net income
         of the Borrowers, before income taxes and non cash extraordinary items.

         7. Insurance. Section 5.10 of the Loan Agreement is hereby deleted in
its entirety and the following is inserted in full substitution thereof:

                  Section 5.10 Insurance. Maintain insurance with insurance
         companies on such of its properties, in such amounts and against such
         risks as is customarily maintained by similar businesses operating in
         the same vicinity; maintain general public liability insurance against
         claims for personal injury, death or property damage in such amounts as
         are commercially 
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         reasonable and worker's compensation insurance in statutory amounts
         with such companies as are licensed to do business in the state
         requiring the same. Notwithstanding the foregoing, the Borrowers may
         "self insure" pursuant to a formal plan adopted and approved by Board
         of Directors of each applicable Borrower, provided that the aggregate
         amount of contingent liability at any time under such self insurance
         plan or plans does not exceed Three Million Dollars ($3,000,000).


         8. Books and Records. Section 5.12 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 5.12 Books and Records. (a) Keep and maintain accurate
         books and records and (b) permit any person designated by the Lender to
         enter the premises of any Borrower and examine, audit and inspect the
         books and records at any reasonable time and from time to time without
         notice, provided, however, that prior to the occurrence and continuance
         of any Event of Default hereunder, the Lender will provide the
         Borrowers with reasonable notice prior to any such examination, audit
         or inspection. Each Borrower will permit any Person designated by the
         Lender to enter the premises of any Borrower and examine, audit and
         inspect the books and records pertaining to any Borrower's ability to
         perform its obligations under any of the Loans at any reasonable time
         and from time to time without notice, at the Borrowers' expense,
         provided, however, that prior to the occurrence and continuance of any
         Event of Default hereunder, the Lender will provide the Borrowers with
         reasonable notice prior to any such examination, audit or inspection,
         and further provided, that the Lender shall not request such audits at
         the Borrowers' expense (which expense will not exceed $5,000 per audit)
         more frequently then once per calendar year, unless an Event of Default
         shall have occurred hereunder and be continuing in which event the
         Lender may request audits more frequently at the Borrowers' joint and
         several expense. All examinations, audits and inspections will be made
         in accordance with each Borrower's security and confidentiality
         policies and procedures.

         9. Environmental Audits. Section 5.15 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 5.15 Environmental Audits. If an Event of Default
         shall have occurred hereunder or under any of the other Loan Documents,
         the Borrowers shall immediately upon the receipt of notice from the
         Lender, which may be given at any time and from time to time by the
         Lender in its sole discretion (but not more frequently than once during
         any twelve (12) month period), cause an Environmental Assessment (as
         hereinafter defined) to be undertaken with respect of any property or
         properties owned or leased by any Borrower and furnish the same to the
         Lender within thirty (30) days after the date of the Lender's request.
         The cost of any such Environmental Assessment shall be borne
         exclusively by the Borrowers. The Borrowers shall cooperate with each
         environmental consulting firm engaged to make any such Environmental
         Assessment and shall supply to each such environmental consulting firm,
         from time to time and promptly on request, all information available to
         the Borrowers 


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         to facilitate the completion of the Environmental Assessment.
         Notwithstanding the foregoing, the Lender shall be under no duty to
         require the preparation of any Environmental Assessment of any such
         properties, and in no event shall any such Environmental Assessment by
         the Lender be or give rise to any representation or warranty by the
         Lender that Hazardous Materials are or are not present on any such
         property, or that there has been compliance by the Borrowers or any
         other person with any Environmental Laws. For purposes hereof,
         "Environmental Assessment" means a report of an environmental
         assessment of the Property of such scope (including but not limited to
         the taking of soil borings and air and groundwater samples and other
         above and below ground testing) as the Lender may request, prepared by
         a recognized environmental consulting firm acceptable to the Lender in
         all respects and sufficient in detail to comply with the Lender's
         established guidelines and the guidelines of any appropriate
         governmental authority. For purposes hereof, "Hazardous Materials"
         means any and all hazardous or toxic substances, wastes or materials
         which, because of their quantity, concentration, or physical, chemical
         or infectious characteristics, may cause or pose a present or potential
         hazard or nuisance to human health, safety or welfare or to the
         environment when used, treated, stored, disposed of, generated,
         manufactured, transported or otherwise handled, including without
         limitation, any substance, waste or material which is or contains
         asbestos, radon, polychlorinated biphenyls, urea formaldehyde,
         explosives, radioactive materials or petroleum products.


         10. Mortgages and Pledges. Section 6.1 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 6.1 Mortgages and Pledges. Create, incur, assume or
         suffer to exist any mortgage, pledge, lien or other material
         encumbrance of any kind upon, or any security interest in, any of its
         property or assets ("Lien"), whether now owned or hereafter acquired,
         except (a) Liens for taxes not delinquent or being contested in good
         faith and by appropriate proceedings, (b) Liens in connection with
         worker's compensation, unemployment insurance or other social security
         obligations, (c) deposits or pledges to secure bids, tenders, contracts
         (other than contracts for the payment of money), leases, statutory
         obligations, surety and appeal bonds and other obligations of like
         nature arising in the ordinary course of business, (d) mechanics',
         worker's, materialmen's, landlords', carriers', or other like Liens
         arising in the ordinary course of business with respect to obligations
         which are not due or which are being contested in good faith, and which
         do not violate the terms of the Deed of Trust, (e) any Lien created in
         connection with the refinancing of indebtedness in existence on the
         date hereof and any Liens securing any extension, renewal or
         replacement of obligations secured by any such Lien, (f) the assumption
         of any Lien in any property hereafter acquired by virtue of any
         Acquisition, existing at the time of such Acquisition; provided,
         however, that (i) the indebtedness secured by any such Lien so created,
         assumed or existing shall not exceed the fair market value of the
         property covered thereby to the entity acquiring the same, (ii) each
         such Lien shall attach only to the property so acquired, (iii) that
         such Lien interest shall not secure any working capital indebtedness,
         (g) any purchase money mortgage, or purchase money security interest in
         any property, or interest therein created or assumed


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         contemporaneously with the purchase of such property, or interest
         therein, to secure or provide for the payment or financing of any part
         of the purchase price thereof; provided, however, that (i) the
         indebtedness secured by such purchase money mortgage or security
         interest shall not exceed one hundred percent (100%) of cost of the
         property covered thereby (ii) each such purchase money mortgage or
         purchase money security interest shall attach only to the property so
         purchased, (iii) the purchase of such property or interest therein to
         which any such purchase money mortgage or purchase money security
         interest relates shall not result in a default under any other
         provision of this Agreement or any Loan Document, and (h) any Liens not
         otherwise covered by clauses (a) through (g) above, in an aggregate
         amount not to exceed Five Hundred Thousand Dollars ($500,000).
         Notwithstanding the foregoing, the Borrowers may grant Liens to secure
         indebtedness in excess of Five Hundred Thousand Dollars ($500,000),
         provided that (i) the aggregate amount secured by such Liens does not
         at any time exceed Five Million Dollars ($5,000,000); and (ii) at the
         time such Lien is granted, the Lender receives a Lien on a pari passu
         basis with the Lien given to any such third party in connection with
         such indebtedness.


         11. Merger or Acquisition. Section 6.3 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 6.3 Merger or Acquisition. Acquire all or
         substantially all the assets, outstanding stock or any other or
         additional interest in, any Person or merge with any Person (each an
         "Acquisition" and collectively, the "Acquisitions"), unless, each of
         the following conditions are met: (a) the acquired entity (the
         "Target") is a going concern, unless the total cash consideration paid
         for the Acquisition is less than or equal to $500,000; (b) the Company
         is the controlling corporation; (c) total cash consideration paid for
         any Acquisition does not exceed Ten Million Dollars ($10,000,000) in
         the aggregate in any fiscal year; and (d) after giving affect to the
         Acquisition, the Borrowers' shall not be in default under this
         Agreement or any of the Loan Documents provided, however, that nothing
         in this Section 6.3 shall be construed to prohibit any Borrower from
         undertaking a joint venture that complies with subsections (a), (c) and
         (d) of this Section, provided, further, that notwithstanding anything
         in this Agreement to the contrary, the Company and/or any of the
         Borrowers may, merge with or into, consolidate with, be liquidated or
         dissolved into the Company, any Borrower, or any other Subsidiary,
         provided that such Subsidiary becomes a party to this Agreement and a
         co-obligor of the Loans. All Targets which are headquartered in the
         United States which survive an Acquisition, where the total cash
         consideration equals or exceeds Five Million Dollars ($5,000,000) will,
         at the Borrowers' expense, be added as a co-obligor of the Loans.

         12. Advances and Loans. Section 6.4 of the Loan Agreement is hereby
deleted in its entirety.

         13. Investments. Section 6.5 of the Loan Agreement is hereby deleted in
its entirety and the following is inserted in full substitution thereof:


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                  Section 6.5 Investments. Except as permitted under Section 6.3
         of this Agreement, make cash investments by purchasing or acquiring the
         obligations or stock of, or any other or additional interest in, any
         Person, except (a) obligations, stock or interest of any Person that is
         or, as a result of such Acquisition, becomes a Subsidiary, (b) publicly
         traded stock not in excess of any amounts permitted by law, (c) general
         obligations of, or obligations unconditionally guaranteed as to
         principal and interest by, the United States of America, (d) bonds,
         debentures, participation certificates or notes issued by any agency or
         corporation which is or may hereafter be created by Act of the Congress
         of the United States as an agency or instrumentality thereof, (e)
         Public Housing Bonds, Temporary Notes or Preliminary Loan Notes, fully
         secured by contracts with the United States, (f) certificates of
         deposit with maturities of one (1) year or less from the date of
         acquisition thereof, or money market accounts maintained with, the
         Lender or any other domestic commercial bank having capital and surplus
         in excess of One Hundred Million Dollars ($100,000,000.00) or such
         other domestic financial institutions or domestic brokerage houses to
         the extent disclosed to, and approved by, the Lender, and (g)
         commercial paper of a domestic issuer rated at least either A-1 by
         Standard & Poor's Corporation or P-1 by Moody's Investors Service, Inc.
         with maturities of six (6) months or less from the date of acquisition.


         14. Subsidiaries. Section 6.6 of the Loan Agreement is hereby deleted
in its entirety and the following is inserted in full substitution thereof:

                  Section 6.6 Subsidiaries. Create or acquire any Subsidiaries
         other than the Subsidiaries existing as of the date hereof and listed
         on EXHIBIT A, or created pursuant to an Acquisition under Section 6.3
         of this Agreement, unless such Subsidiaries do not own any material
         assets or such Subsidiaries are added as a co-makers or co-guarantors,
         as the case may be, of the Loans. Notwithstanding the foregoing, it is
         understood and agreed that the Lender will not require any of the
         Released Parties or MAL, MA Holding, MA BioServices GmbH and BIOMEVA
         GmbH or any Subsidiary of the foregoing or any Subsidiary hereafter
         created under the laws of any country other than the United States
         (collectively, the "Excluded Subsidiaries") to either pledge any of
         their respective assets to secure the Loans or to be added as co-makers
         or co-guarantors of the Loans. The Borrowers each jointly and severally
         agree not to cumulatively transfer, sell or assign in the aggregate
         more than ten percent (10%) of their respective assets to any of the
         Excluded Subsidiaries, unless each such Excluded Subsidiary is added as
         a co-maker or co-guarantor, of the Loans.

         15. Stock of Subsidiaries. Section 6.7 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 6.7 Stock of Subsidiaries. Sell or otherwise dispose
         of any shares of capital stock of any Subsidiary which when taken in
         the aggregate exceed ten percent (10%) of the capital stock of such
         Subsidiary (except in connection with the merger or consolidation of


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         any solvent Wholly Owned Subsidiary into the Company or with another
         solvent Wholly Owned Subsidiary or the dissolution of any Subsidiary).

         16. Sale and Leaseback. Section 6.9 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 6.9 Sale and Leaseback. Directly or indirectly enter
         into any arrangement to cumulatively sell or transfer more than ten
         percent (10%) of its fixed assets in the aggregate then owned by it and
         there upon or within one year thereafter rent or lease the assets so
         sold or transferred.

         17. Line of Business. Section 6.10 of the Loan Agreement is hereby
deleted in its entirety and the following is inserted in full substitution
thereof:

                  Section 6.10 Line of Business. Enter into any lines or areas
         of business outside of the life sciences field.

         18. Events of Default. Sections 7.1, 7.2, 7.4, 7.6, 7.7 and 7.8 of the
Loan Agreement are hereby deleted in their entirety and the following are
inserted in full substitution thereof:

                  Section 7.1 Failure to Pay. The Borrowers shall fail to make
         any payment of principal or interest on any of the Obligations, when
         and as the same shall become due and payable and such failure shall
         continue for a period of five (5) days after notice thereof.

                  Section 7.2 Breach of Representations and Warranties. Any
         information contained in any financial statement, schedule, report or
         any other material document delivered by any Borrower or any other
         party or parties on behalf of any Borrower to the Lender in connection
         with any of the Loans proves at any time to be not in all material
         respects true and accurate, as of the time made or any Borrower or any
         such other party or parties shall have failed to state any material
         fact or any fact necessary to make such information not misleading, or
         any representation or warranty contained in this Agreement, the Loan
         Documents, or in any other material document, certificate or opinion
         delivered by any Borrower to the Lender in connection with any of the
         Loans, proves at any time to be incorrect or misleading in any material
         respect as of the time made.

                  Section 7.4 Other Defaults. Any Borrower shall default in the
         due observance or performance of any other term, covenant or agreement
         herein contained and such default shall continue uncured for thirty
         (30) days after notice thereof shall have been given to such Borrower
         by the Lender, unless (a) the nature of the failure is such that it
         cannot be cured within the thirty (30) day period, (b) the Borrower
         institutes corrective action within the thirty (30) day period, and (c)
         the Borrower complete the cure within a period of an additional sixty
         (60) days.


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                  Section 7.6 Receiver; Bankruptcy. Any Borrower shall (a) apply
         for or consent to the appointment of a receiver, trustee or liquidator
         for itself or any of its property, (b) admit in writing its inability
         to pay its debts as they mature, (c) make a general assignment for the
         benefit of creditors, (d) be adjudicated a bankrupt or insolvent, (e)
         file a voluntary petition in bankruptcy or a petition or an answer
         seeking reorganization or an arrangement with creditors or to take
         advantage of any bankruptcy, reorganization, insolvency, readjustment
         of debt, dissolution or liquidation law or statute, or an answer
         admitting the material allegations of a petition filed against it in
         any proceeding under any such law or if corporate action shall be taken
         by any Borrower for the purposes of effecting any of the foregoing, or
         (f) by any act indicate its consent to, approval of or acquiescence in
         any such proceeding or the appointment of any receiver of or trustee
         for any of its property, or suffer any such receivership, trusteeship
         or proceeding to continue undischarged for a period of ninety (90)
         days.

                  Section 7.7 Judgment. Unless adequately insured in the opinion
         of the Lender, the entry of a final judgment for the payment of money
         involving more than $5,000,000 in excess of any amounts covered by
         insurance against any Borrower and the failure by any Borrower to
         discharge the same, or cause it to be discharged or vacated, within
         sixty (60) days from the date of the order, decree or process under
         which or pursuant to which such judgment was entered, or to secure a
         stay of execution pending appeal of such judgment.

                  Section 7.8 Default Under Other Borrowings. Default shall be
         made with respect to any evidence of indebtedness or liability for
         borrowed money in excess of $5,000,000 (other than the Loan) or any
         operating or capital lease having a value in excess of $5,000,000 if
         the effect of such default is to accelerate the maturity of such
         evidence of indebtedness or liability.

         19. Performance by Lender and Other Remedies. Sections 8.2 and 8.3 of
the Loan Agreement are hereby deleted and restated in their entirety and the
following are inserted in full substitution thereof:

                    Section 8.2 Performance by Lender. Upon the occurrence of an
         Event of Default, if any Borrower shall fail to pay the Obligations or
         otherwise fail to perform, observe or comply with any of the material
         conditions, covenants, terms, stipulations or agreements contained in
         this Agreement or any of the other Loan Documents, the Lender without
         notice to or demand upon the Borrowers and without waiving or releasing
         any of the Obligations or any Event of Default, may (but shall be under
         no obligation to) at any time thereafter make such payment or perform
         such act for the account and at the expense of the Borrowers, and may
         enter upon the premises of each Borrower for that purpose and take all
         such action thereon as the Lender may consider necessary or appropriate
         for such purpose. All sums so paid or advanced by the Lender and all
         costs and expenses (including, without limitation, reasonable
         attorneys' fees and expenses) incurred in connection therewith (the
         "Expense Payments") together with interest thereon from the date of
         payment, advance or incurring 


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         until paid in full at the Default Rate payable under the Notes shall be
         paid by the Borrowers to the Lender on demand and shall constitute and
         become a part of the Obligations.

                  Section 8.3 Other Remedies. Upon the occurrence of an Event of
         Default (and in addition to all of its rights, powers and remedies
         under this Agreement), the Lender shall have all of the rights and
         remedies under applicable laws.


         20. Material Adverse Change. Section 7.9 of the Loan Agreement is
hereby deleted in its entirety.

         21. Conditions Precedent. This Agreement shall become effective on the
date the Lender receives the following documents, each of which shall be
satisfactory in form and substance to the Lender:

                  (a) The Second Replacement Revolving Promissory Note issued
and delivered by the Borrowers in the form of EXHIBIT B attached hereto and
incorporated herein by reference, payable to the order of the Lender in the
maximum principal amount of One Million Dollars ($1,000,000) (the "Line of
Credit Replacement Note");

                  (b) The Second Deed of Trust Note Modification Agreement
issued and delivered by and among the Borrowers and the Lender in the form of
EXHIBIT D attached hereto and incorporated herein by reference (the "Deed of
Trust Note Modification");

                  (c) The Second Note Modification Agreement issued and
delivered by and among the Borrowers and the Lender in the form of EXHIBIT E
attached hereto and incorporated herein by reference (the "Term Note
Modification Agreement"); and

                  (d) A Third Modification Agreement - Leasehold Deed of Trust
and Security Agreement by and among the Company, the trustees named therein and
the Lender, in the form of EXHIBIT F attached hereto and incorporated herein by
reference (the "Deed of Trust Modification").

         22.      MISCELLANEOUS

                  (a) Notices. From and after the date hereof, the address for
notice for the Borrower is hereby revised as follows:

                             BioReliance Corporation
                             9900 Blackwell Road
                             Rockville, Maryland 20850
                             Attn: General Counsel

      with a copy to:        Shulman, Rogers, Gandal, Pordy & Ecker, P.A.
                             11921 Rockville Pike, 3rd Floor


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<PAGE>   10
                             Rockville, Maryland 20852
                             Attn: Rebecca Oshoway, Esquire

                  (b) Acknowledgments. The Borrowers hereby confirm to the
Lender the enforceability and validity of each of the Loan Documents. In
addition, the Borrowers hereby agree to the execution and delivery of this
Agreement and the terms and provisions, covenants or agreements contained in
this Agreement shall not in any manner , impair, lessen, modify, waive or
otherwise limit the liability and obligations of the Borrowers under the terms
of any of the Loan Documents, except as otherwise specifically set forth in this
Agreement. The Borrowers issue, remake, ratify and confirm the representations,
warranties and covenants contained in the Loan Documents. Nothing in this
Agreement shall be deemed to waive any defaults existing under any of the Loan
Documents as of the date hereof.


                  (c) ENTIRE AGREEMENT. NO STATEMENTS, AGREEMENTS OR
REPRESENTATIONS, ORAL OR WRITTEN, WHICH MAY HAVE BEEN MADE TO ANY OF THE
BORROWERS OR TO ANY EMPLOYEE OR AGENT OF ANY OF THE BORROWERS, EITHER BY THE
LENDER OR BY ANY EMPLOYEE, AGENT OR BROKER ACTING ON THE LENDER'S BEHALF, WITH
RESPECT TO THE MODIFICATION OF THE LOANS, SHALL BE OF ANY FORCE OR EFFECT,
EXCEPT TO THE EXTENT STATED IN THIS AGREEMENT, AND ALL PRIOR AGREEMENTS AND
REPRESENTATIONS WITH RESPECT TO THE MODIFICATION OF THE LOANS ARE MERGED HEREIN.

                  (d) Survival of Agreement; Successors and Assigns. All
covenants, agreements, representations and warranties made by the Borrowers
herein and in any certificate, in the Loan Documents and in any other
instruments or documents delivered pursuant hereto shall survive the making by
the Lender of the Loans and the execution and delivery of the Notes, and shall
continue in full force and effect so long as any of the Obligations are
outstanding and unpaid. Whenever in this Agreement any of the parties hereto is
referred to, such reference shall be deemed to include the successors and
assigns of such party; and all covenants, promises and agreements by or on
behalf of the Borrowers, which are contained in this Agreement shall inure to
the benefit of the successors and assigns of the Lender, and all covenants,
promises and agreements by or on behalf of the Lender which are contained in
this Agreement shall inure to the benefit of the permitted successors and
permitted assigns of the Borrowers, but this Agreement may not be assigned by
the Borrowers without the prior written consent of the Lender.

                  (e) Expenses. The Borrowers agree to pay all reasonable
out-of-pocket expenses of the Lender (including the reasonable fees and expenses
of its legal counsel) in connection with the preparation of this Agreement, the
recordation of all financing statements and such other instruments as may be
required by the Lender subsequent to the execution of this Agreement to secure
the Obligations (including any and all recordation tax and other costs and taxes
incident to recording), the enforcement of any provision of this Agreement and
the collection of the Obligations. The Borrowers agree to indemnify and save
harmless the Lender for any liability resulting from the failure to pay any
required recordation tax, transfer taxes, recording costs or any other expenses
incurred by the Lender in connection with the Obligations. The provisions of
this Section shall 


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survive the execution and delivery of this Agreement and the repayment of the
Obligations. The Borrowers further agree to reimburse the Lender upon demand for
all reasonable out-of-pocket expenses (including reasonable attorneys' fees and
legal expenses) incurred by the Lender in enforcing any of the Obligations or
any security therefor, which agreement shall survive the termination of this
Agreement and the repayment of the Obligations.

                  (f) Counterparts. This Agreement may be executed in any number
of multiple counterparts, each of which shall be deemed an original hereof and
all of which when taken together shall constitute one and the same instrument.
It shall not be necessary that the signature of, or on behalf of, each party, or
that the signature of the persons required to bind any party, appear on more
than one counterpart.

                  (g) Governing Law. This Agreement shall be governed by, and
construed in accordance with the laws of the State of Maryland.

                  (h) Modifications. No modification or waiver of any provision
of this Agreement or of any of the other Loan Documents, nor consent to any
departure by the Borrowers therefrom, shall in any event be effective unless the
same shall be in writing, and then such waiver or consent shall be effective
only in the specific instance and for the purpose for which given. No notice to
or demand on the Borrowers in any case shall entitle the Borrowers to any other
or further notice or demand in the same, similar or other circumstance.

                  (i) Illegality. If fulfillment of any provision hereof or any
transaction related hereto or to any of the other Loan Documents, at the time
performance of such provision shall be due, shall involve transcending the limit
of validity prescribed by law, then ipso facto, the obligation to be fulfilled
shall be reduced to the limit of such validity; and if any clause or provisions
herein contained other than the provisions hereof pertaining to repayment of the
Obligations operates or would prospectively operate to invalidate this Agreement
in whole or in part, then such clause or provision only shall be void, as though
not herein contained, and the remainder of this Agreement shall remain operative
and in full force and effect; and if such provision pertains to repayment of the
Obligations, then, at the option of the Lender, all of the Obligations of the
Borrowers to the Lender shall become immediately due and payable.

                  (j) Headings. The headings in this Agreement are for
convenience only and shall not limit or otherwise affect any of the terms
hereof.

                  (k) ARBITRATION. ANY CONTROVERSY OR CLAIM BETWEEN OR AMONG THE
PARTIES HERETO INCLUDING BUT NOT LIMITED TO THOSE ARISING OUT OF THIS AGREEMENT,
THE LOAN DOCUMENTS OR ANY RELATED INSTRUMENTS, AGREEMENTS OR DOCUMENTS,
INCLUDING ANY CLAIM BASED ON OR ARISING FROM AN ALLEGED TORT, SHALL BE
DETERMINED BY BINDING ARBITRATION IN ACCORDANCE WITH THE FEDERAL ARBITRATION ACT
(OR IF NOT APPLICABLE, THE APPLICABLE STATE LAW), THE RULES OF PRACTICE AND


                                       11
<PAGE>   12
PROCEDURE FOR ARBITRATION OF COMMERCIAL DISPUTES OF ENDISPUTE, INC., D/B/A
J.A.M.S./ENDISPUTE ("J.A.M.S.") AND THE "SPECIAL RULES" SET FORTH BELOW. IN THE
EVENT OF AN INCONSISTENCY, THE SPECIAL RULES SHALL CONTROL. JUDGMENT UPON ANY
ARBITRATION AWARD MAY BE ENTERED IN ANY COURT HAVING JURISDICTION. ANY PARTY TO
THIS INSTRUMENT, AGREEMENT OR DOCUMENT MAY BRING ANY ACTION, INCLUDING A SUMMARY
OR EXPEDITED PROCEEDING, TO COMPEL ARBITRATION OF ANY CONTROVERSY OR CLAIM TO
WHICH THIS INSTRUMENT, AGREEMENT OR DOCUMENT RELATES IN ANY COURT HAVING
JURISDICTION OVER SUCH ACTION.


                  (A) SPECIAL RULES. THE ARBITRATION SHALL BE CONDUCTED IN
MONTGOMERY COUNTY, MARYLAND AND ADMINISTERED BY J.A.M.S. WHO WILL APPOINT AN
ARBITRATOR. IF J.A.M.S. IS UNABLE OR LEGALLY PRECLUDED FROM ADMINISTERING THE
ARBITRATION, THEN THE AMERICAN ARBITRATION ASSOCIATION WILL SERVE. ALL
ARBITRATION HEARINGS WILL BE COMMENCED WITHIN NINETY (90) DAYS OF THE DEMAND FOR
ARBITRATION; FURTHER, THE ARBITRATOR SHALL ONLY, UPON A SHOWING OF CAUSE, BE
PERMITTED TO EXTEND THE COMMENCING OF SUCH HEARING FOR AN ADDITIONAL SIXTY (60)
DAYS.

                  (B) RESERVATION OF RIGHTS. NOTHING IN THIS INSTRUMENT,
AGREEMENT OR DOCUMENT SHALL BE DEEMED TO: (I) LIMIT THE APPLICABILITY OF ANY
OTHERWISE APPLICABLE STATUTES OF LIMITATION OR REPOSE AND ANY WAIVERS CONTAINED
IN THIS INSTRUMENT, AGREEMENT OR DOCUMENT; OR (II) BE A WAIVER BY THE LENDER OF
THE PROTECTION AFFORDED TO IT BY 12 U.S.C. Section91 OR ANY SUBSTANTIALLY
EQUIVALENT STATE LAW; OR (III) LIMIT THE RIGHT OF THE LENDER: (A) TO EXERCISE
SELF HELP REMEDIES (BUT NOT INCLUDING SETOFF), OR (B) TO FORECLOSE AGAINST ANY
REAL OR PERSONAL PROPERTY COLLATERAL, OR (C) TO OBTAIN FROM A COURT PROVISIONAL
OR ANCILLARY REMEDIES SUCH AS (BUT NOT LIMITED TO) INJUNCTIVE RELIEF, WRIT OF
POSSESSION OR THE APPOINTMENT OF A RECEIVER. THE LENDER MAY EXERCISE SUCH SELF
HELP RIGHTS, FORECLOSE UPON SUCH PROPERTY, OR OBTAIN SUCH PROVISIONAL OR
ANCILLARY REMEDIES BEFORE, DURING OR AFTER THE PENDENCY OF ANY ARBITRATION
PROCEEDING BROUGHT PURSUANT TO THIS INSTRUMENT, AGREEMENT OR DOCUMENT. NEITHER
THE EXERCISE OF SELF HELP REMEDIES NOR THE INSTITUTION OR MAINTENANCE OF ANY
ACTION FOR FORECLOSURE OR FOR PROVISIONAL OR ANCILLARY REMEDIES SHALL CONSTITUTE
A WAIVER OF THE RIGHT OF ANY PARTY, INCLUDING THE CLAIMANT IN SUCH ACTION, TO
ARBITRATE THE MERITS OF THE CONTROVERSY OR CLAIM OCCASIONING RESORT TO SUCH
REMEDIES.


                                       12
<PAGE>   13
                     [SIGNATURES ARE ON THE FOLLOWING PAGE]



                                       13
<PAGE>   14
         IN WITNESS WHEREOF, the parties hereto have signed and sealed this
Agreement on the day and year first above written.


WITNESS/ATTEST:                             BIORELIANCE CORPORATION


______________________________              By:__________________________(SEAL)
                                               Name:
                                               Title:

WITNESS/ATTEST:                             MA BIOSERVICES, INC.


______________________________              By:__________________________(SEAL)
                                               Name:
                                               Title:

WITNESS/ATTEST:                             MAGENTA CORPORATION


______________________________              By:__________________________(SEAL)
                                               Name:
                                               Title:

WITNESS/ATTEST:                             MAGENTA VIRAL PRODUCTION, INC.


______________________________              By:__________________________(SEAL)
                                               Name:
                                               Title:

WITNESS:                                    NATIONSBANK, N.A.


______________________________              By:__________________________(SEAL)
                                               Elizabeth F. Shore
                                               Vice President