Exhibit 10.2

MORGAN STANLEY SENIOR FUNDING, INC.
1585 Broadway
New York, New York 10036

CONFIDENTIAL

April 15, 2007

Quest Diagnostics Incorporated
1290 Wall Street West
Lyndhurst, NJ 07071
Attention: Joseph P. Manory, Vice President and Treasurer

Project Nightingale - Commitment Letter

Ladies and Gentlemen:

You have advised us that Quest Diagnostics Incorporated (the "Borrower") intends
to acquire (the "Acquisition") all of the outstanding common stock of a certain
company that you have confidentially identified to us (the "Target"). In
connection with the Acquisition, you have requested that Morgan Stanley Senior
Funding, Inc. (“Morgan Stanley”) provide you with a financing commitment for
100% of the Senior Bank Financing (as defined and described below). You have
further advised us that for purposes of consummating the Transaction (as defined
below) and for ongoing working capital and general corporate purposes, the
following financing will be required on the date the Acquisition is to be
consummated (the “Closing Date”):

           a)     

A senior unsecured credit facility in an aggregate amount of $2,250,000,000 to
be provided by Morgan Stanley and certain other financial institutions (the
“Bank Lenders”), which facilities shall consist of a $1,500,000,000 term loan
facility (the “Term Loan Facility”) and a $750,000,000 revolving credit facility
(the “Revolving Credit Facility”, together with the Term Loan Facility, the
“Senior Credit Facilities”), having substantially the terms set forth in Exhibit
A hereto (such Exhibit, together with Exhibit B referred to below, being the
“Term Sheets” and, together with this letter, this “Commitment Letter”). Subject
to the terms and conditions set forth in Exhibit A, the committed amounts of
each of the Senior Credit Facilities may be increased by up to $250,000,000.

    b)

A senior unsecured bridge loan facility of up to $1,100,000,000 (the "Bridge
Loan Facility", together with the Senior Credit Facilities, the “Senior Bank
Financing”) to be provided by Morgan Stanley and certain other financial
institutions (the “Bridge Lenders” and, together with the Bank Lenders, the
“Lenders”) having substantially the terms set forth in Exhibit B hereto (as
defined below). You have informed us that, after the consummation of the
Acquisition, you expect to issue up to $1,100,000,000 of senior notes or other
securities (the "Securities") which will be used to repay the Bridge Loan
Facility.

 

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You have further informed us that no other external debt financing other than
the Term Loan Facility and Bridge Loan Facility will be required to consummate
the Acquisition.

The Acquisition, the entering into and funding of the Senior Bank Financing, the
issuance and sale of the Securities and all related transactions, including the
refinancing of (x) the Borrower’s existing debt, including (i) the Amended and
Restated Credit Agreement, dated as of April 20, 2004, among the Borrower,
certain of the Borrower’s subsidiaries, as Guarantors, the Lenders (as defined
therein), and Bank of America, N.A., as Administrative Agent and (ii) the
Interim Credit Agreement, dated as of January 31, 2007, among the Borrower,
certain of the Borrower’s subsidiaries, as Guarantors, the Lenders (as defined
therein), and Bank of America, N.A., as Administrative Agent (the credit
agreements described in clauses (i) and (ii) above being, collectively, the
“Existing Credit Facilities”) and (y) the Target’s existing debt (collectively,
the “Refinancing”), and the payment of related fees, costs and expenses are
collectively referred to as the "Transaction".

Our affiliate, Morgan Stanley & Co., Incorporated ("MSCI") has also delivered to
you a separate engagement letter, dated the date hereof (the "Engagement
Letter"), setting forth, among other things, the terms on which MSCI is willing
to act as the exclusive lead arranger and lead bookrunner for the Securities.

In connection with the foregoing, and upon and subject to the terms and
conditions set forth herein and in the Term Sheets, Morgan Stanley is pleased to
offer its commitment to lend, or to cause one or more of its affiliates to lend
on the Closing Date, 100% of the $3,350,000,000 Senior Bank Financing.

Subject to the terms and conditions of this Commitment Letter, Morgan Stanley
shall act as (i) the sole lead arranger, and sole book-runner in respect of each
of the Senior Credit Facilities and the Bridge Loan Facility (in such
capacities, the “Lead Arranger”) and (ii) the administrative agent for each of
the Senior Credit Facilities and the Bridge Loan Facility. It is understood that
Morgan Stanley shall be permitted to designate, in consultation with you, one or
more Lenders as agents or co-agents, as the case may be, but no other agents,
co-agents, or arrangers will be appointed, no other titles may be given, and no
other compensation (other than as expressly set forth in the Term Sheets or in
the fee letter, dated the date hereof, among Morgan Stanley and the Borrower and
executed simultaneously herewith (the “Fee Letter”)) will be paid without Morgan
Stanley’s prior written consent; provided that the Borrower shall have the right
to appoint (x) one additional institution to act as joint lead arranger and book
runner, (y) additional documentation agents and syndication agents for the
Senior Bank Financings and (z) one other financial institution to act as
administrative agent under the Senior Credit Facilities, in each case subject to
(i) the consent of Morgan Stanley (not to be unreasonably withheld or delayed)
and (ii) economics and commitment amounts to be mutually agreed upon by you and
us. Fees payable to the syndicate of Lenders shall be payable from the amounts
payable pursuant to the Fee Letter.

Morgan Stanley reserves the right, prior to or after execution of the definitive
documentation for the Senior Bank Financing, to syndicate all or part of its
commitment for the Senior Bank Financing to one or more lending institutions, in
consultation with you, that will become parties

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to such definitive documentation pursuant to a syndication managed by Morgan
Stanley; provided that (i) if you receive the Minimum Ratings (as defined in the
Fee Letter), you will have the right to consent to any lending institution that
(x) is not a commercial bank or (y) you have previously identified to Morgan
Stanley in writing, in each case prior to such lending institution becoming a
member of the Senior Bank Financing syndicate, such consent not to be
unreasonably withheld or delayed, and (ii) you acknowledge that such syndicate
will include financial institutions other than (and in addition to) those party
to the Existing Credit Facilities. The commitments of Morgan Stanley hereunder
shall be reduced as and when commitments are received from the Lenders. If
requested, you agree to actively assist Morgan Stanley in achieving a
syndication of the Senior Bank Financing that is satisfactory to us and you.
Such assistance shall include (i) your providing and causing your advisors to
provide us and the Lenders, upon request and on a confidential basis, with all
information reasonably deemed necessary by us to complete syndication, including
but not limited to information and evaluations prepared by you and your advisors
or on your behalf relating to the Transaction; (ii) if needed, assistance in the
preparation of an Offering Memorandum (which shall be acceptable to you) to be
used in connection with the syndication; (iii) your using commercially
reasonable efforts to ensure that the syndication efforts benefit materially
from your and the Target’s existing lending relationships; and (iv) otherwise
assisting us in our syndication efforts, including by making senior management
and advisors of the Borrower and its subsidiaries available, and using
commercially reasonable best efforts to make the Target’s senior officers and
representatives available, in each case, from time to time to attend and make
presentations regarding the business and prospects of the Borrower and its
subsidiaries and the Target, as appropriate, at a reasonable number of meetings
of prospective Lenders. In addition, you agree that until the Successful
Syndication (as defined in the Fee Letter) of the Senior Bank Financing has
occurred and the Lenders have executed and delivered the definitive
documentation with respect to the Senior Bank Financing, no competing offering,
placement or arrangement of any bank financing by or on behalf of the Borrower
or any of its subsidiaries shall be syndicated, privately placed or publicly
offered, other than bilateral foreign currency facilities, the receivables
facility with Quest Diagnostics Receivables Incorporated, bilateral letter of
credit and acceptance facilities replacing existing letter of credit and
acceptance facilities, and other financings in the ordinary course of business
of the Borrower and its subsidiaries; provided that, to the extent any such
other financings in the ordinary course constitute arrangements for borrowed
money, the aggregate amount of such financings shall not exceed $150,000,000.

Subject to the condition that prior to the existence of an event of default you
shall have the right to consent to any assignments (such consent not to be
unreasonably withheld), it is understood and agreed that Morgan Stanley, in
consultation with you, will manage all aspects of the syndication, including
decisions as to the selection of proposed Lenders reasonably acceptable to you
and any titles offered to proposed Lenders, when commitments will be accepted
and the final allocations of the commitments among the Lenders. It is understood
that no Lender participating in the Senior Bank Financing will receive
compensation from you in order to obtain its commitment, except on the terms
contained in this Commitment Letter and in the Fee Letter, it being understood
that the foregoing is in no way intended to restrict the Borrower and its
subsidiaries from entering into financing arrangements with, or paying
compensation to, a Lender other than in connection with the Senior Bank
Financing, so long as such other financing arrangement is permitted hereunder.
It is also understood and agreed among all the parties

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hereto that any syndication of the Senior Bank Financing will reduce the
exposure of Morgan Stanley hereunder.

You hereby represent, warrant and covenant that (i) all information, taken as a
whole (excluding information of a general economic nature), other than the
Projections (as defined below), which has been or is hereafter made available to
us or the Lenders by you or any of your representatives in connection with the
transactions contemplated hereby (the "Information") is and will be complete and
correct in all material respects and does not and will not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements contained therein not misleading, and (ii) all financial
projections concerning the Borrower and its subsidiaries or the Target that have
been or are hereafter made available to us or the Lenders by you or any of your
representatives (the "Projections") have been or will be prepared in good faith
based upon assumptions you believe at the time to be reasonable; provided that,
with respect to the Projections, it is understood that actual results may differ
materially from any Projections provided. You agree to furnish us with such
Information and Projections as we may reasonably request and to supplement such
Information and the Projections from time to time until the Closing Date for the
Senior Bank Financing so that the representation, warranty and covenant in the
preceding sentence is correct on such closing date. You understand that in
arranging and syndicating the Senior Bank Financing, Morgan Stanley will be
using and relying on the Information and the Projections without independent
verification thereof. The representations and covenants contained in this
paragraph shall remain effective until definitive documentation with respect to
the Senior Bank Financing is executed and delivered and, thereafter, the
disclosure representations contained herein shall terminate and be of no further
force and effect. You agree to continue to provide or cause to be provided to
the Lenders material information received by you or on your behalf or of which
you become aware that is related to or affects the Borrower, the Target or any
of their respective subsidiaries or any aspect of the Transaction.

By acceptance of this offer, the Borrower agrees to pay all reasonable due
diligence and legal expenses incurred before the date hereof and all reasonable
out-of-pocket fees and expenses (including reasonable attorneys' fees and
expenses and due diligence expenses) incurred after the date hereof by us in
connection with the Senior Bank Financing and the syndication thereof (whether
of not the Senior Bank Financing is consummated). We agree to notify you of the
then outstanding legal fees incurred by us in connection herewith upon your
request.

You agree to indemnify and hold harmless Morgan Stanley, MSCI, each Lender and
each of their respective affiliates and their respective directors, officers,
agents and employees (each an "Indemnitee") from and against any and all
liabilities, losses, damages, and costs and expenses of any kind arising out of
or relating to this letter or the transactions contemplated hereby, the Senior
Bank Financing, the use of loan proceeds or the commitments, including without
limitation, the reasonable fees and disbursements of counsel, which may be
incurred by such Indemnitee in connection with any investigation,
administrative, or judicial proceeding (whether or not such Indemnitee shall be
a designated party thereto); provided that no Indemnitee shall have the right to
be indemnified hereunder for such Indemnitee's own, or its affiliate’s or its
directors’, officers’, agents’ and employees’, gross negligence, willful
misconduct or bad faith as determined in a final non-appealable judgment by a
court of competent jurisdiction. You agree

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to reimburse each Indemnitee for any such indemnified amounts as the same are
incurred by such Indemnitee. In the case of an investigation, litigation or
proceeding to which the indemnity in this paragraph applies, such indemnity
shall be effective whether or not such investigation, litigation or proceeding
is brought by you, your equity holders or creditors or an Indemnitee, whether or
not an Indemnitee is otherwise a party thereto and whether or not the
transactions contemplated hereby are consummated. No Indemnitee shall be liable
(i) for any action taken by it or not taken by it in the absence of its own
gross negligence or willful misconduct, including any action or inaction in
connection with the use by others of Information or other materials obtained
through the internet, Intralinks or other similar electronic telecommunications
or other information transmission systems in connection with the Senior Bank
Financing or (ii) for any special, indirect, consequential, punitive, or
indirect damages. This indemnification and limitation of liability shall survive
and continue for the benefit of the Indemnitees at all times after the
Borrower's acceptance of this Commitment Letter, notwithstanding any failure of
the Closing Date for the Senior Bank Financing to occur. It is further agreed
that Morgan Stanley shall only have liability to you (as opposed to any other
person) and that Morgan Stanley shall be liable solely in respect of its own
commitment to the Senior Bank Financing, and that such liability shall only
arise to the extent damages have been caused by a breach of Morgan Stanley’s
obligations hereunder to negotiate, in good faith, definitive documentation for
the Senior Bank Financing on the terms set forth herein, as determined in a
final, non-appealable judgment by a court of competent jurisdiction.

The terms of this Commitment Letter, the Engagement Letter and the Fee Letter
are confidential and, except for disclosure on a confidential basis to our and
your respective accountants, attorneys and other professional advisors retained
in connection with the Senior Bank Financing or as may be required by law, rule
or regulation or regulatory authority, may not be disclosed by any party hereto
in whole or in part to any other person or entity without the prior written
consent of each other party hereto; provided that it is understood and agreed
that you may disclose the terms of this Commitment Letter (but not the Fee
Letter or the Engagement Letter) (i) on a confidential basis to the board of
directors and advisors of the Target in connection with their consideration of
the Acquisition and (ii) after your acceptance hereof, in filings with the SEC
and other applicable regulatory authorities, and in proxy and other materials
disseminated to stockholders. In connection with and solely for the purposes of
services and transactions contemplated hereby, you agree that Morgan Stanley is
permitted to access, use and share with any of their bank or non-bank
affiliates, agents, advisors (legal or otherwise) or representatives or with any
potential lenders in connection with the syndication of the Senior Bank
Financing on a confidential basis, any information concerning the Borrower and
its subsidiaries related to this financing that is or may come into the
possession of Morgan Stanley and MSCI or any of such affiliates. We hereby
notify you that pursuant to the requirements of the USA PATRIOT Act, Title III
of Pub. L. 107-56 (signed into law October 26, 2001) (the "Act"), we are
required to obtain, verify and record information that identifies you, which
information includes your name and address and other information that will allow
us to identify you in accordance with the Act. This notice is given in
accordance with the requirements of the PATRIOT Act and is effective as to
Morgan Stanley and each Lender. In addition, it is a condition to our commitment
hereunder that we receive, at least five business days prior to the Closing
Date, all documentation and other information required by regulatory authorities
under applicable “know your customer” and anti-money laundering rules and
regulations, including without limitation the PATRIOT Act.

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It is understood and agreed by all parties hereto that the Bridge Facility shall
be refinanced in full by the Borrower as soon as reasonably practicable
following the Closing Date. In connection therewith, the Borrower agrees in good
faith to take all such action as may be necessary to refinance or repay the
entire amount of the funding under the Bridge Facility as soon as reasonably
practicable after the closing thereof, including, without limitation, with the
proceeds of a senior note offering as set forth in the Engagement Letter.

In connection with all aspects of each transaction contemplated by this
Commitment Letter, you acknowledge and agree, and acknowledge your affiliates'
understanding, that: (i) agreements and arrangements of the parties hereto
described in this letter result from arm's-length commercial negotiations
between you and your affiliates, on the one hand, and Morgan Stanley and MSCI,
on the other hand, and you are capable of evaluating and understanding and
understand and accept the terms, risks and conditions of the transactions
contemplated by this letter; (ii) in connection with the process leading to the
agreements and arrangements described herein, Morgan Stanley and MSCI is and has
been acting solely as a principal and is not the financial advisor, agent or
fiduciary for you or any of your affiliates, stockholders, creditors or
employees or any other party; (iii) neither Morgan Stanley nor MSCI has assumed
or will assume an advisory, agency or fiduciary responsibility in your or your
affiliates' favor with respect to any of the transactions contemplated hereby or
the process leading thereto (irrespective of whether either Morgan Stanley or
MSCI advised or is currently advising you or your affiliates on other matters)
and neither Morgan Stanley nor MSCI has any obligation to you or your affiliates
with respect to the transactions contemplated hereby except those obligations
expressly set forth in this Commitment Letter; (iv) Morgan Stanley and MSCI and
their respective affiliates may be engaged in a broad range of transactions that
involve interests that differ from yours and your affiliates and Morgan Stanley
and MSCI have no obligation to disclose any of such transactions or interests by
virtue of any advisory, agency or fiduciary relationship; and (v) Morgan Stanley
and MSCI have not provided any legal, accounting, regulatory or tax advice with
respect to any of the agreements, arrangements or transactions contemplated
hereby and you have consulted your own legal, accounting, regulatory and tax
advisors to the extent you have deemed appropriate. Nothing in this Commitment
Letter is in any way intended to limit the scope of the engagement of Morgan
Stanley or the obligations of Morgan Stanley pursuant to its engagement by you
as financial advisor in connection with the Acquisition, or your rights and
remedies in connection therewith.

You acknowledge and agree that in connection with all aspects of each
transaction contemplated by this Commitment Letter, you and your affiliates and
Morgan Stanley and MSCI and any of their affiliates through which any of any of
them may be acting (each a “Transaction Affiliate”) have an arms-length business
relationship that creates no fiduciary duty on the part of Morgan Stanley and
MSCI or any Transaction Affiliate and each party hereto expressly disclaims any
fiduciary relationship.

The provisions of the immediately preceding six paragraphs shall remain in full
force and effect notwithstanding the termination of this letter or any
commitment or undertaking hereunder and regardless of whether any definitive
documentation for the Senior Bank Financing shall be executed.

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This Commitment Letter, the Fee Letter and the Engagement Letter may be executed
in counterparts which, taken together, shall constitute an original. Delivery of
an executed counterpart of this Commitment Letter, the Engagement Letter or the
Fee Letter by telecopier or facsimile (or other electronic transmission) shall
be effective as delivery of a manually executed counterpart hereof and thereof.

This Commitment Letter, the Fee Letter and the Engagement Letter shall be
governed by, and construed in accordance with, the laws of the State of New
York. Each of you and us hereby irrevocably waives any and all right to trial by
jury in any action, proceeding or counterclaim (whether based on contract, tort
or otherwise) arising out of or relating to this Commitment Letter (including,
without limitation, the Term Sheets), the Fee Letter, the Engagement Letter, the
Transaction, the transactions contemplated hereby and thereby or the actions of
Morgan Stanley and MSCI in the negotiation, performance or enforcement hereof.

This Commitment Letter, the Fee Letter and Engagement Letter, embodies the
entire agreement and understanding among us, you and your affiliates with
respect to the Senior Bank Financing and supersedes all prior agreements and
understandings relating to the specific matters hereof. No party has been
authorized by any of us to make any oral or written statements that are
inconsistent with this Commitment Letter. This Commitment Letter is not
assignable by the Borrower without our prior written consent and is intended to
be solely for the benefit of the parties hereto and the Indemnitees.

This offer will expire at 5:00 p.m. New York City time on the earliest to occur
of (i) May 4, 2007, (ii) the date you are informed that your bid for the Target
has been rejected in favor of a competing bid or as a result of the termination
of the sale process relating to the Target, and (iii) 5:00 p.m. New York City
time on the date following the date upon which the definitive purchase agreement
with respect to the Acquisition is executed by you; provided that, in the case
of clause (i) or (iii), this offer will not expire as aforesaid if you execute
this Commitment Letter, the Fee Letter and the Engagement Letter, return them to
us prior to that time (which may be by facsimile transmission), in which event
this Commitment Letter, the Fee Letter and the Engagement Letter (each of which
may be signed in one or more counterparts) shall become binding agreements.
Thereafter, our undertakings and commitments provided for herein will expire on
June 30, 2007 unless definitive documentation for the Senior Bank Financing is
executed and delivered prior to such date.

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We are pleased to have the opportunity to work with you in connection with this
important financing.

Very truly yours,

MORGAN STANLEY SENIOR FUNDING, INC.

By: s/ Jaap Tonckens
Name: Jaap Tonckens
Title: Vice President

Agreed and accepted as of the date hereof:

QUEST DIAGNOSTICS INCORPORATED

By: s/ Joseph P. Manory
Name: Joseph P. Manory
Title: Vice President and Treasurer

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EXHIBIT A

SUMMARY OF CERTAIN TERMS AND CONDITIONS
FOR THE QUEST DIAGNOSTICS INCORPORATED
$2,250,000,000 SENIOR CREDIT FACILITIES

I.           The Parties

Borrower: Quest Diagnostics Incorporated, a Delaware corporation (the  
“Borrower”).   Lead Arranger and   Book Runner: Morgan Stanley Senior Funding,
Inc. (“Morgan Stanley” and, in such   capacities, the “Lead Arranger”).  
Syndication Agent: To be determined.   Swingline Lender: To be determined.  
Letter of Credit Issuer: To be determined.   Administrative Agent: Morgan
Stanley (in such capacity, the “Administrative Agent”).   Lenders: Morgan
Stanley and a syndicate of financial institutions arranged by   Morgan Stanley,
which institutions shall be acceptable to the Borrower   and the Administrative
Agent (the “Bank Lenders”).   Guarantors: All obligations under the Senior
Credit Facilities (as defined below) shall   be unconditionally guaranteed by
all material wholly-owned domestic   existing and future direct and indirect
subsidiaries of the Borrower (other   than Quest Diagnostics Receivables
Incorporated and certain other   exceptions to be agreed following a detailed
review of the Target’s   capital structure) (all of such subsidiaries being,
collectively, the   “Guarantors”). All guarantees shall be guarantees of payment
and not   of collection.

II.     Description of Senior Credit Facilities

General Description   of Senior Credit Facilities: A maximum amount of
$2,250,000,000 in senior financing to be   provided to the Borrower pursuant to
a term A loan facility (the “Term   Loan Facility”) and a revolving credit
facility (the “Revolving Credit   Facility”). The Term Loan Facility and the
Revolving Credit Facility are   collectively referred to herein as the “Senior
Credit Facilities”. Loans   made under the Senior Credit Facilities are herein
collectively referred to   as “Loans”, with Loans under the Term Loan Facility
being herein   collectively referred to as “Term Loans” and Loans under the
Revolving   Credit Facility being herein collectively referred to as “Revolving
  Loans”.

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A.           Term Loan Facility

Term Loan Facility   Commitment Amount: $1,500,000,000; provided that, if prior
to the Closing Date (as defined   below) there are financial institutions
willing to commit to make Term   Loans in excess of $1,500,000,000, at the
option of the Borrower, the   Term Loan Facility Commitment Amount may be
increased on the   Closing Date up to an additional $250,000,000.   Maturity and
Amortization: The final maturity of the Term Loan Facility shall be the fifth  
anniversary of the Closing Date (as defined below) (the “Term Loan   Maturity
Date”). The Term Loans shall be repaid in equal quarterly   amounts, subject to
amortization of (i) 5% in each of the first two years   commencing on the last
day of the first full fiscal quarter ending after the   Closing Date, (ii) 10%
in each of years three and four and (iii) 70% in   the final year prior to the
Term Loan Maturity Date.   Use of Proceeds: Proceeds of the Term Loans shall be
used to finance, in part, the   acquisition of 100% of the capital stock of the
Target (the   “Acquisition”), the refinancing of certain existing debt of the
Borrower   and the Target, including the Existing Credit Facilities
(collectively, the   “Refinancing”) and all related transactions, including the
payment of   related fees, costs and expenses (collectively, the “Transaction”).
Availability: Term Loans may only be borrowed on the date the Acquisition is  
consummated (the “Closing Date”). No amount of Term Loans once   repaid may be
reborrowed.

B.      Revolving Credit Facility

Revolving Credit Facility   Commitment Amount: $750,000,000.   Maturity: The
final maturity of the Revolving Credit Facility shall be the fifth   anniversary
of the Closing Date (the “Revolving Loan Commitment   Termination Date”).
Revolving Loans shall be repaid in full on the   Revolving Loan Commitment
Termination Date and all Letters of Credit   (as defined below) issued under the
Revolving Credit Facility shall   terminate prior to such date.   Use of
Proceeds: Proceeds of the Revolving Loans may be used for purposes of the  
Refinancing, and for the Borrower’s working capital requirements and   other
general corporate purposes, including acquisitions.   Revolving Credit  
Facility Availability: Pursuant to the Revolving Credit Facility, Revolving
Loans may be   borrowed, prepaid and reborrowed by the Borrower from time to
time   prior to the Revolving Loan Commitment Termination Date. The   Revolving
Credit Facility will also contain sub-facilities for (i) the   issuance of
letters of credit (“Letters of Credit”) in an amount not to   exceed
$150,000,000, (ii) Revolving Loans to be borrowed in Euros,   Sterling and other
currencies agreed by the Lenders in an equivalent

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  amount not to exceed $100,000,000 and (iii) competitive bid loans (the  
“Competitive Bid Loans”).     The Revolving Credit Facility will also contain a
sub-facility for   swingline loans in an amount to be determined (the “Swingline
Loans”   and each a “Swingline Loan”) on same-day notice. Any Swingline Loan  
will reduce availability under the Revolving Credit Facility on a dollar-  
for-dollar basis.   Incremental Revolving Credit   Facility: After the Closing
Date, the Senior Credit Facilities will permit the   Borrower to increase
commitments under the Revolving Credit Facility   (any such increase, an
“Incremental Revolving Facility”) in an   aggregate amount of up to
$250,000,000; provided that (i) no Bank   Lender will be required to participate
in any such Incremental Revolving   Facility, (ii) no event of default or
default exists or would exist after   giving effect thereto, and (iii) any
Incremental Revolving Facility shall   be on terms and pursuant to documentation
applicable to the Revolving   Credit Facility.

III.     Terms Applicable to the Entire Senior Credit Facilities

Closing Date: No later than July 31, 2007 or such later date as the parties to
the   Purchase Agreement (defined below) may agree pursuant to Section   10.1.4
thereof, but in any event not later than December 31, 2007.   Interest Rates: At
the option of the Borrower, Loans may be maintained from time to   time
(including on the Closing Date) as (i) Base Rate Loans which shall   bear
interest at the Base Rate (as defined below) in effect from time to   time or
(ii) Eurodollar Loans which shall bear interest at the Eurodollar   Rate (to be
defined substantially as such term is defined in the Existing   Credit
Facilities) (adjusted for maximum reserves) as determined by the  
Administrative Agent for the respective interest period plus the   Applicable
Margin in effect from time to time. All Swingline Loans   shall bear interest at
a rate per annum equal to the Base Rate.     The “Applicable Margin” means the
appropriate applicable percentages   corresponding to the Debt Rating (as
defined below) of the Borrower in   effect as described on Annex I to this
Summary of Terms and Conditions   (this “Term Sheet”).     “Base Rate” shall
mean the higher of (i) 1/2 of 1% in excess of the   federal funds rate and (ii)
the rate published in the Wall Street Journal as   the “prime rate” (or
equivalent), in each case as in effect from time to   time.     “Debt Rating”
means the long-term senior unsecured non-credit   enhanced debt rating of the
Borrower from Standard & Poor’s Rating   Services (“S&P”) and Moody’s Investors
Service, Inc. (“Moody’s”).

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  During the continuance of a payment event of default under the definitive  
documentation with respect to the Senior Credit Facilities or an event of  
default of the type describe in clause 10 of the section entitled “Events of  
Default” below (the “Loan Documentation”), the Applicable Margin   then in
effect on all obligations owing under the Loan Documentation   shall increase by
2% per annum; provided that, in any such event, Base   Rate Loans shall be
deemed to have an “Applicable Margin” of 2%     Interest periods of 1, 2, 3 and
6 months shall be available in the case of   Eurodollar Loans. Interest periods
for the Competitive Bid Loans shall   be substantially similar to those
available under the Existing Credit   Facilities.     Interest in respect of
Base Rate Loans shall be payable quarterly in   arrears on the last business day
of each fiscal quarter. Interest in respect   of Eurodollar Loans and
Competitive Bid Loans shall be payable in   arrears at the end of the applicable
interest period and every three months   in the case of Eurodollar Loans with
interest periods in excess of three   months. Interest will also be payable at
the time of repayment of any   Loans, and at maturity. All interest and
commitment fee and other fee   calculations shall be based on a 360-day year (or
365 or 366 days, as the   case may be, in the case of Base Rate Loans).  
Arrangement and   Administrative   Agency Fees: The Lead Arranger and the
Administrative Agent shall receive such fees   as have been separately agreed
upon with the Borrower.   Facility Fee: Commencing on the Closing Date, a
non-refundable per annum fee (the   “Facility Fee”) equal to the applicable
percentages corresponding to the   Debt Rating of the Borrower in effect as
described on Annex I to this   Term Sheet will accrue on the Revolving Credit
Facility commitments   (whether or not then used or available), payable
quarterly in arrears and   on the final maturity of the Revolving Credit
Facility (whether by stated   maturity or otherwise).   Voluntary Commitment  
Reductions: Voluntary reductions to the unutilized portion of the Senior Credit
  Facilities, including the Revolving Credit Facility, may be made from   time
to time by the Borrower without premium or penalty.   Voluntary Prepayment: The
Borrower may, upon at least one business day’s notice in the case of   Base Rate
Loans and three business days’ notice in the case of   Eurodollar Loans, prepay,
in full or in part, the Senior Credit Facilities   without premium or penalty;
provided, that each partial prepayment shall   be applied in direct order of
maturity and in an amount of $5,000,000 or   an integral multiple of $1,000,000
in excess thereof; provided further   that any such prepayment of Eurodollar
Loans shall be made together   with reimbursement for any funding losses of the
Bank Lenders resulting   therefrom.

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Documentation: The commitments will be subject to the negotiation, execution and
  delivery of definitive Loan Documentation consistent with the terms of   this
Term Sheet, in each case prepared by counsel to the Lead Arranger.   Conditions
Precedent to           the Closing Date:   The availability of the Senior Credit
Facilities shall be conditioned     upon satisfaction of each of the following
conditions precedent on      or before the Closing Date:       (a)      The
indebtedness under the Bridge Credit Agreement, dated       as of the date of
the Loan Documentation (the “Bridge       Credit Agreement”), among the Borrower
and Morgan       Stanley, as Administrative Agent, shall be funded in an      
amount necessary to consummate the Acquisition       concurrently with the
funding of the Senior Credit Facilities,       and the Bridge Credit Agreement
shall not have been       amended or modified in any manner that is adverse to
the       Bank Lenders in any material respect without the consent of       the
Lead Arranger, which consent shall not be unreasonably       withheld.       (b)
Concurrently with the funding of the Term Loan Facility, the       Acquisition
shall be consummated pursuant to a purchase       agreement between the Borrower
and the seller of the Target       and certain of their respective affiliates.
Such purchase       agreement shall be substantially in the form of the draft,  
    dated April 15, 2007, delivered to Lead Arranger (the       “Purchase
Agreement”); provided that the Purchase       Agreement shall not have been
amended or modified nor       shall any conditions precedent set forth therein
have been       amended or waived (in whole or in part), in any manner that    
  is adverse to the Bank Lenders or the Transaction in any       material
respect, without the consent of the Lead Arranger,       which consent shall not
be unreasonably withheld.       (c) The Borrower, the Guarantors, the
Administrative Agent and       the Bank Lenders shall have executed the Loan    
  Documentation, which shall be reasonably satisfactory to the       Bank
Lenders and shall be substantially similar to the       Existing Credit
Facilities and consistent with the terms       hereof.       (d) All costs, fees
and expenses of the Lead Arranger and the       Bank Lenders (including the fees
and expenses of counsel       for the Lead Arranger and local counsel (to the
extent       utilized) for Morgan Stanley) for which the Borrower shall      
have been presented an invoice at least three business days       prior to the
Closing Date shall have been paid.       (e) The Administrative Agent shall have
received all customary       closing documents and instruments, including (i)
satisfactory

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opinions of counsel and (ii) other customary corporate resolutions,
organizational documents,
 
certificates and documents.
          (f)     
All necessary governmental and third party consents and
     
approvals shall have been obtained (without the imposition
     
of any conditions that are not reasonably acceptable to the
     
Bank Lenders) and shall remain in effect and all applicable
     
waiting periods shall have expired without any adverse
     
action being taken by any competent authority.
      (g)
No later than one week prior to the launch of the primary
     
syndication of the Senior Credit Facilities, the Borrower
     
shall have delivered five year financial projections prepared
     
on a pro forma basis giving effect to the Transaction as if the
     
Transaction had occurred as of the most recent fiscal quarter
     
ended prior to the Closing Date. Such projections shall be
     
prepared in good faith based upon reasonable assumptions at
     
the time such projections are delivered.
      (h)
The commitments under the Existing Credit Facilities shall
     
have been terminated and all principal, interest, fees and
     
other amounts outstanding thereunder shall have been repaid
     
in full.
      (i)
The Lead Arranger shall have received all documentation
     
and other information required by bank regulatory
     
authorities under applicable “know your customer” and anti-
     
money laundering rules and regulations, including without
     
limitation the PATRIOT Act.
      (j)
No Material Adverse Change (as defined in the Purchase
     
Agreement) shall have occurred.
  Conditions Precedent       to All Extensions of       Credit:
There shall exist no default under any of the Loan Documentation, and
 
the representations and warranties of the Borrower and each of the
 
Guarantors therein shall be true and correct immediately prior to, and
  after giving effect to, such extension of credit.    
Notwithstanding anything in the Commitment Letter, the Term Sheets,
 
the Fee Letter, the definitive documentation for any of the Senior Credit
 
Facilities or any other letter agreement or other undertaking concerning
 
the financing of the Transaction to the contrary (but subject to the
 
Borrower’s compliance with its agreements and obligations under the
 
Commitment Letter in all material respects), (i) the only representations
 
and warranties the making of which shall be a condition to availability of
 
the Senior Credit Facilities on the Closing Date shall be (A) such of the
 
representations made by or on behalf of the Target in the Purchase
 
Agreement as are material to the interests of the Bank Lenders, but only

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  to the extent that the Borrower has the right to terminate its obligations  
under the Purchase Agreement as a result of a breach of such   representations
in the Purchase Agreement, (B) the representations and   warranties set forth in
the Commitment Letter, (C) that no matured event   of default shall have
occurred and be continuing under the Senior Credit   Facilities, and (D) the
Specified Representations (as defined below), and   (ii) the terms of the
definitive documentation for the Senior Credit   Facilities shall be in a form
such that they do not impair availability of   the Senior Credit Facilities on
the Closing Date if the conditions set forth   in the Commitment Letter and
under the heading “Conditions Precedent   to the Closing Date” herein are
satisfied. For purposes hereof,   “Specified Representations” means the
representations and warranties   set forth in the Term Sheet relating to
organization, corporate power and   authority, due authorization, execution,
delivery and the enforceability of   the Loan Documentation, Federal Reserve
margin regulations and the   Investment Company Act.   Representations and  
Warranties: Substantially similar to those contained in the Existing Credit
Facilities   (including with respect to exceptions, baskets, materiality and  
qualifications), including:

1. due organization, good standing, licensing and accreditation and  
authorization; 2. non-contravention; 3. governmental approval; 4. accuracy of
information and financial statements; 5. identity of subsidiaries; 6. execution,
delivery and enforceability of the Loan   Documentation; 7. solvency; 8. title
to properties and liens; 9. payment of taxes; 10. compliance with laws and
contracts in all material respects; 11. environmental and ERISA matters; 12.
consents and approvals; 13. use of proceeds; 14. no default; 15. insurance; 16.
intellectual property; 17. margin regulations and Investment Company Act; and
18.           full disclosure.

  For the avoidance of doubt, the foregoing representations shall not   include
a no material adverse change representation.   Covenants: Substantially similar
to those contained in the Existing Credit Facilities   (including with respect
to exceptions and baskets), including:

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(a) Affirmative Covenants:   1. compliance with laws and regulations (including,
without   limitation, ERISA and environmental laws); 2. payment of taxes and
other obligations; 3. maintenance of appropriate and adequate insurance; 4.
preservation of corporate existence, rights (charter and   statutory),
franchises, permits, licenses and approvals; 5. visitation and inspection
rights; 6. keeping of proper books in accordance with generally accepted  
accounting principles; 7. maintenance of properties; 8. performance of leases,
related documents and other material   agreements; 9. use of proceeds; 10.
customary financial and other reporting requirements; 11. additional credit
parties; and 12.           clinical laboratory compliance programs.   (b)
Negative Covenants – Restrictions on:   1. liens; 2. indebtedness (with
exceptions for the loans incurred under the   Bridge Credit Agreement),
guaranties or other contingent   obligations; 3. mergers and consolidations; 4.
sale/leasebacks; 5. sales, transfers and other dispositions of assets (other
than sales   of inventory in the ordinary course of business); 6. loans,
acquisitions, joint ventures and other investments; 7. repurchasing shares of
capital stock following the occurrence of   a default or an event of default
under the Loan Documentation; 8. transactions with affiliates; 9. changing the
nature of its business; and 10. changing fiscal year, accounting policies or
reporting practices.     (c) Financial Covenants – Maintenance of:   1. a
maximum ratio of total debt to EBITDA not to exceed (x)   3.50:1.00 through June
30, 2008 and (y) 3.25:1.00 thereafter, or   such other levels as may be mutually
agreed upon; and   2. a minimum ratio of EBITDA to interest expense of at least
  3.50:1.00, or such other levels as may be mutually agreed upon.   The
foregoing financial terms and ratios shall be defined in a manner satisfactory
to the Borrower and the Lead Arranger. All of the financial covenants will be
calculated on a consolidated and pro forma basis and for each consecutive four
fiscal quarter period.

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Events of Default: Substantially similar to those contained in the Existing
Credit Facilities   (including with respect to grace periods, notice periods,
monetary   thresholds and other qualifications), including:

1. failure to pay principal when due, or to pay interest or other   amounts
within three business days after the same becomes due,   under the Loan
Documentation;   2. any representation or warranty proving to have been
materially   incorrect when made or confirmed;   3. failure to perform or
observe covenants set forth in the Loan   Documentation within a specified
period of time, where   customary and appropriate, after notice or knowledge of
such   failure;   4. cross-defaults to other indebtedness in an amount in excess
of   $150,000,000;   5. bankruptcy and insolvency defaults (with a grace period
for   involuntary proceedings);   6. monetary judgment defaults in an amount in
excess of   $150,000,000;   7. impairment of Loan Documentation;   8. change of
ownership or operating control;   9. standard ERISA defaults; and  
10.           a material adverse change in the business, operations, properties
  or conditions (financial or otherwise) of the Borrower and its   subsidiaries,
taken as a whole, shall have occurred and be   continuing on the 45th day
following the Closing Date.

Expenses: The Borrower shall pay all of the Administrative Agent’s and the Lead
  Arranger’s due diligence, syndication (including printing, distribution   and
bank meetings), transportation, computer, duplication, appraisal,   audit,
insurance, consultant, search, filing and recording fees and all   other
out-of-pocket expenses incurred by the Administrative Agent or the   Lead
Arranger (including the fees and expenses of counsel for the Lead   Arranger),
whether or not any of the transactions contemplated hereby   are consummated, as
well as all expenses of the Administrative Agent in   connection with the
administration of the Loan Documentation   (including, without limitation, fees
and expenses incurred in connection   with the preparation of the Loan
Documentation (and waivers or   amendments thereto) or the “work-out” or
restructuring of the   obligations). The Borrower shall also pay the expenses of
the   Administrative Agent, the Lead Arranger and the Bank Lenders

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  (including the fees and expenses of counsel) in connection with the  
enforcement of any of the Loan Documentation.   Indemnity: The Borrower will
indemnify and hold harmless the Administrative   Agent, the Lead Arranger, each
Bank Lender and each of their affiliates   and their officers, directors,
employees, agents and advisors from claims   and losses relating to the
Transaction or the Senior Credit Facilities,   other than in the case of gross
negligence, willful misconduct or bad faith   of the indemnified party as
finally determined by a court of competent   jurisdiction.   Required Lenders:
Bank Lenders holding loans and commitments representing more than   50% of the
aggregate amount of loans and commitments under the   Senior Credit Facilities
(the “Required Lenders”).   Waivers &   Amendments: Amendments and waivers of
the provisions of the Loan Documentation   will require the approval of the
Required Lenders, except that the consent   of all affected Bank Lenders will be
required with respect to certain   customary issues, including but not limited
to (i) increases in   commitment amounts, (ii) reductions of principal,
interest, or fees,   (iii) extensions of scheduled maturities or times for
payment, and  
(iv) releases of any material guarantee.
  Assignments and   Participations: Assignments may be non-pro rata and must be
to Eligible Assignees (to   be defined) and, in each case other than an
assignment to a Bank Lender   or an assignment of the entirety of a Bank
Lender’s interest in the Senior   Credit Facilities, in a minimum amount of
$5,000,000. Each Bank   Lender will also have the right, without consent of the
Borrower or the   Administrative Agent, to assign (i) as security all or part of
its rights   under the Loan Documentation to any Federal Reserve Bank and (ii)
all   or part of its rights or obligations under the Loan Documentation to any  
of its affiliates. No participation shall include voting rights, other than  
for reductions or postponements of amounts payable.   Taxes: All payments are to
be free and clear of any present or future taxes,   withholdings or other
deductions whatsoever (other than income taxes in   the jurisdiction of the Bank
Lender’s applicable lending office). The   Borrower will indemnify the Bank
Lenders and the Administrative Agent   for such taxes paid by the Bank Lenders
or the Administrative Agent.   Miscellaneous: Standard yield protection
(including compliance with risk-based capital   guidelines, increased costs,
payments free and clear of withholding taxes   and interest period breakage
indemnities), eurodollar illegality and   similar provisions, defaulting lender
provisions, “yank-a-bank”   provisions, waiver of jury trial, and submission to
jurisdiction provisions.   Governing Law: State of New York.   Counsel for
Morgan Stanley: Mayer, Brown, Rowe & Maw LLP.

A-10

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ANNEX I

DEBT RATINGS GRID

                Applicable Percentage for Applicable Percentage for Facility  
Debt Rating Eurodollar Loans Fee           >BBB+ from S&P/   .320%   . 080%  
>Baa1 from Moody’s       >BBB but < BBB+ from S&P/   .400%   . 100%   >Baa2 but
<Baa1 from Moody’s       >BBB- but <BBB from S&P/   .500%   . 125%   >Baa3 but
<Baa2 from Moody’s       >BB+ but < BBB- from S&P/   .575%   .175%   >Ba1 but
<Baa3 from Moody’s       <BB+ or unrated by S&P/   1.000%   .250%   <Ba1 or
unrated by Moody’s    

If at any time there is a split in the Borrower’s Debt Ratings between S&P and
Moody’s, the applicable percentages shall be determined by the higher of the two
Debt Ratings (i.e. the lower pricing); provided that if the two Debt Ratings are
more than one level apart, the applicable percentage shall be based on the Debt
Rating which is one level higher than the lower rating.

A-11

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EXHIBIT B

SUMMARY OF CERTAIN TERMS AND CONDITIONS
FOR THE QUEST DIAGNOSTICS INCORPORATED
$1,100,000,000 BRIDGE LOAN FACILITY

IV.          The Parties

Borrower: Quest Diagnostics Incorporated, a Delaware corporation (the  
“Borrower”).   Lead Arranger and   Book Runner: Morgan Stanley Senior Funding,
Inc. (“Morgan Stanley” and, in such   capacities, the “Lead Arranger”).  
Syndication Agent: To be determined.   Administrative Agent: Morgan Stanley (in
such capacity, the “Administrative Agent”).   Lenders: Morgan Stanley and a
syndicate of financial institutions arranged by   Morgan Stanley, which
institutions shall be acceptable to the Borrower   and the Administrative Agent
(the “Bridge Lenders”).   Guarantors: All obligations under the Bridge Loan
Facility (as defined below) shall   be unconditionally guaranteed by all
material wholly-owned domestic   existing and future direct and indirect
subsidiaries of the Borrower (other   than Quest Diagnostics Receivables
Incorporated and certain other   exceptions to be agreed following a detailed
review of the Target’s   capital structure) (all of such subsidiaries being,
collectively, the   “Guarantors”). All guarantees shall be guarantees of payment
and not   of collection.

V.           Description of Bridge Loan Facility

Bridge Loan Facility   Commitment Amount: A maximum amount of $1,100,000,000 in
senior financing to be   provided to the Borrower pursuant to a bridge loan
facility (the “Bridge   Loan Facility”). Loans made under the Bridge Loan
Facility are herein   collectively referred to as “Bridge Loans”.   Maturity and
Amortization: The final maturity of the Bridge Loan Facility shall be the date
that is   364 days after the Closing Date (as defined below) (the “Bridge Loan  
Maturity Date”). The Bridge Loans will not amortize prior to the Bridge   Loan
Maturity Date. Bridge Loans shall be repaid in full on the Bridge   Loan
Maturity Date.   Use of Proceeds: Proceeds of the Bridge Loans shall be used to
finance, in part, the   acquisition of 100% of the capital stock of the Target
(the   “Acquisition”), the refinancing of certain existing debt of the Borrower
  and the Target, including the Existing Credit Facilities, (collectively, the  
“Refinancing”), and all related transactions, including the payment of   related
fees, costs and expenses (collectively, the “Transaction”).

B-1

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Availability: Bridge Loans may be borrowed pursuant to no more than two
drawings,   with the first drawing being made on the Closing Date; provided that
the   aggregate amount of all such drawing shall not exceed the Bridge Loan  
Facility Commitment Amount. Up to $400,000,000 of the Bridge Loans   (the
“Delayed Draw Bridge Loans”) may be borrowed pursuant to a   second drawing on
or prior to the 90th day following the Closing Date, or   such later date as may
be mutually agreed upon (the “Delayed Draw   Commitment Termination Date”), to
pay the principal of, and any   accrued and unpaid interest on, the Target’s
existing debt. No amount of   Bridge Loans once repaid may be reborrowed.  
Closing Date: No later than July 31, 2007 or such later date as the parties to
the   Purchase Agreement (defined below) may agree pursuant to Section   10.1.4
thereof, but in any event not later than December 31, 2007.   Interest Rates: At
the option of the Borrower, Bridge Loans may be maintained from   time to time
(including on the Closing Date) as (i) Base Rate Loans   which shall bear
interest at the Base Rate (as defined below) in effect   from time to time or
(ii) Eurodollar Loans which shall bear interest at the   Eurodollar Rate (to be
defined substantially as such term is defined in the   Existing Credit
Facilities) (adjusted for maximum reserves) as   determined by the
Administrative Agent for the respective interest period   plus the Applicable
Margin in effect from time to time.     The “Applicable Margin” means the
appropriate applicable percentages   corresponding to the Debt Rating (as
defined below) of the Borrower in   effect as described on Annex I to this
Summary of Terms and Conditions   (this “Term Sheet”).     “Base Rate” shall
mean the higher of (i) 1/2 of 1% in excess of the   federal funds rate and (ii)
the rate published in the Wall Street Journal as   the “prime rate” (or
equivalent), in each case as in effect from time to   time.     “Debt Rating”
means the long-term senior unsecured non-credit   enhanced debt rating of the
Borrower from Standard & Poor’s Rating   Services (“S&P”) and Moody’s Investors
Service, Inc. (“Moody’s”).     During the continuance of a payment event of
default under the definitive   documentation with respect to the Bridge Loan
Facility (the “Bridge   Loan Documentation”), or an event of default of the type
described in   clause 10 of the section entitled “Events of Default” below the  
Applicable Margin then in effect on all obligations owing under the   Bridge
Loan Documentation shall increase by 2% per annum; provided   that, in any such
event, Base Rate Loans shall be deemed to have an   “Applicable Margin” of 2%.  
  Interest periods of 1, 2, 3 and 6 months shall be available in the case of  
Eurodollar Loans.

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  Interest in respect of Base Rate Loans shall be payable quarterly in   arrears
on the last business day of each fiscal quarter. Interest in respect   of
Eurodollar Loans shall be payable in arrears at the end of the   applicable
interest period and every three months with interest periods in   excess of
three months. Interest will also be payable at the time of   repayment of any
Bridge Loans, and at maturity. All interest and   commitment fee and other fee
calculations shall be based on a 360-day   year (or 365 or 366 days, as the case
may be, in the case of Base Rate   Loans).   Bridge Funding   Fees: Bridge
Funding Fees equal to (i) 0.15% will be payable on December 31,   2007 and (ii)
0.10% will be payable on February 29, 2008, in each case   on the principal
amount under the Bridge Loan Facility then outstanding.   Commitment Fee:
Commencing on the Closing Date, a non-refundable per annum fee (the  
“Commitment Fee”) equal to the applicable percentages corresponding   to the
Debt Rating of the Borrower in effect as described on Annex I to   this Term
Sheet will accrue on the unused portion of Bridge Loan   Facility commitments,
payable quarterly in arrears and on the earliest of   (i) the termination in
full of the Bridge Loan Facility commitments, (ii)   the borrowing of all
available amounts under the Bridge Loan Facility   commitments and (iii) the
Delayed Draw Commitment Termination   Date.   Voluntary Commitment   Reductions:
Voluntary reductions to the unutilized portion of the Bridge Loan   Facility may
be made from time to time by the Borrower without   premium or penalty.  
Voluntary Prepayment: The Borrower may, upon at least one business day’s notice
in the case of   Base Rate Loans and three business days’ notice in the case of
  Eurodollar Loans, prepay, in full or in part, the Bridge Loan Facility  
without premium or penalty; provided, that each partial prepayment shall   be in
an amount of $5,000,000 or an integral multiple of $1,000,000 in   excess
thereof; provided further that any such prepayment of Eurodollar   Loans shall
be made together with reimbursement for any funding losses   of the Bridge
Lenders resulting therefrom.   Mandatory Prepayment: The Bridge Loan Facility
will be required to be prepaid with (a) 100% of   the net cash proceeds of the
issuance or incurrence of funded debt   (excluding debt incurred under the
Senior Credit Agreement (as defined   below)), and (b) 100% of the net cash
proceeds from any issuance of   equity securities in any public offering or
private placement (subject to   baskets and exceptions to be agreed upon,
including carve-outs for   accounts receivable securitizations and stock options
exercised in the   ordinary course).   Documentation: The commitments will be
subject to the negotiation, execution and   delivery of definitive Bridge Loan
Documentation consistent with the

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  terms of this Term Sheet, in each case prepared by counsel to the Lead  
Arranger.   Conditions Precedent to       The Closing Date and       the Bridge
Loans:       The availability of the Bridge Loan Facility shall be conditioned  
  upon satisfaction of each of the following conditions precedent on     or
before the Closing Date:       (k)      The Term Loan under the Credit
Agreement, dated as of the       date of the Bridge Loan Documentation (the
“Senior Credit       Agreement”), among the Borrower and Morgan Stanley, as    
  Administrative Agent, shall be funded concurrently with the       funding of
the Bridge Loan Facility, and the Senior Credit       Agreement shall not have
been amended or modified in any       manner that is adverse to the Bridge
Lenders in any material       respect without the consent of the Lead Arranger,
which       consent shall not be unreasonably withheld.       (l) Concurrently
with the funding of the Term Loan Facility, the       Acquisition shall be
consummated pursuant to a purchase       agreement between the Borrower and the
seller of the Target       and certain of their respective affiliates. Such
purchase       agreement shall be substantially in the form of the draft,      
dated April 15, 2007, delivered to the Lead Arranger (the       “Purchase
Agreement”); provided that the Purchase       Agreement shall not have been
amended or modified nor       shall any conditions precedent set forth therein
have been       amended or waived (in whole or in part), in any manner that    
  is adverse to the Bridge Lenders or the Transaction in any       material
respect, without the consent of the Lead Arranger,       which consent shall not
be unreasonably withheld.       (m) The Borrower, the Guarantors, the
Administrative Agent and       the Bridge Lenders shall have executed the Bridge
Loan       Documentation, which shall be reasonably satisfactory to the      
Bridge Lenders and shall be substantially similar to the       Existing Credit
Facilities and consistent with the terms       hereof.       (n) All costs, fees
and expenses of the Lead Arranger and the       Bridge Lenders (including the
fees and expenses of counsel       for the Lead Arranger and local counsel (to
the extent       utilized) for Morgan Stanley) for which the Borrower shall    
  have been presented an invoice at least three business days       prior to the
Closing Date shall have been paid.       (o) The Administrative Agent shall have
received all customary       closing documents and instruments, including (i)
satisfactory       opinions of counsel and (ii) other customary corporate

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           resolutions, organizational documents, certificates and      
documents.       (p)     
All necessary governmental and third party consents and
     
approvals shall have been obtained (without the imposition
     
of any conditions that are not reasonably acceptable to the
     
Bridge Lenders) and shall remain in effect and all applicable
     
waiting periods shall have expired without any adverse
     
action being taken by any competent authority.
      (q)
No later than one week prior to the launch of the primary
     
syndication of the Bridge Loan Facility, the Borrower shall
     
have delivered five year financial projections prepared on a
     
pro forma basis giving effect to the Transaction as if the
     
Transaction had occurred as of the most recent fiscal quarter
     
ended prior to the Closing Date. Such projections shall be
     
prepared in good faith based upon reasonable assumptions at
     
the time such projections are delivered.
      (r)
The commitments under the Existing Credit Facilities shall
     
have been terminated and all principal, interest, fees and
     
other amounts outstanding thereunder shall have been repaid
     
in full.
      (s)
The Lead Arranger shall have received all documentation
     
and other information required by bank regulatory
     
authorities under applicable “know your customer” and anti-
     
money laundering rules and regulations, including without
      limitation the PATRIOT Act.       (t)
No Material Adverse Change (as defined in the Purchase
     
Agreement) shall have occurred.
  Additional Conditions       Precedent:
There shall exist no default under any of the Bridge Loan
 
Documentation, and the representations and warranties of the Borrower
 
and each of the Guarantors therein shall be true and correct immediately
  prior to, and after giving effect to, the Bridge Loans.    
Notwithstanding anything in the Commitment Letter, the Term Sheets,
 
the Fee Letter, the definitive documentation for any of the Bridge Loan
 
Facility or any other letter agreement or other undertaking concerning the
 
financing of the Transaction to the contrary (but subject to the
 
Borrower’s compliance with its agreements and obligations under the
 
Commitment Letter in all material respects), (i) the only representations
 
and warranties the making of which shall be a condition to availability of
 
the Bridge Loan Facility on the Closing Date shall be (A) such of the
 
representations made by or on behalf of the Target in the Purchase
 
Agreement as are material to the interests of the Bridge Lenders, but only
 
to the extent that the Borrower has the right to terminate its obligations
  under the Purchase Agreement as a result of a breach of such

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  representations in the Purchase Agreement, (B) the representations and  
warranties set forth in the Commitment Letter, (C) that no matured event   of
default shall have occurred and be continuing under the Senior Credit  
Facilities, and (D) the Specified Representations (as defined below) and   (ii)
the terms of the definitive documentation for the Bridge Loan   Facility shall
be in a form such that they do not impair availability of the   Bridge Loan
Facility on the Closing Date if the conditions set forth in the   Commitment
Letter under the heading “Conditions Precedent to the   Closing Date and the
Bridge Loans” herein are satisfied. For purposes   hereof, “Specified
Representations” means the representations and   warranties set forth in the
Term Sheet relating to organization, corporate   power and authority, due
authorization, execution, delivery and the   enforceability of the Loan
Documentation, Federal Reserve margin   regulations and the Investment Company
Act.       Representations and   Warranties: Substantially similar to those
contained in the Existing Credit Facilities   (including with respect to
exceptions, baskets, materiality and   qualifications), including:

1. due organization, good standing, licensing and accreditation and  
authorization; 2. non-contravention; 3. governmental approval; 4. accuracy of
information and financial statements; 5. identity of subsidiaries; 6. execution,
delivery and enforceability of the Loan   Documentation; 7. solvency; 8. title
to properties and liens; 9. payment of taxes; 10. compliance with laws and
contracts in all material respects; 11. environmental and ERISA matters; 12.
consents and approvals; 13. use of proceeds; 14. no default; 15. insurance; 16.
intellectual property; 17. margin regulations and Investment Company Act; and
18.           full disclosure.

Covenants: Substantially similar to those contained in the Existing Credit
Facilities   (including with respect to exceptions and baskets), including:    
(a)           Affirmative Covenants:     1. compliance with laws and regulations
(including, without     limitation, ERISA and environmental laws);   2. payment
of taxes and other obligations;

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  3. maintenance of appropriate and adequate insurance;   4. preservation of
corporate existence, rights (charter and     statutory), franchises, permits,
licenses and approvals;   5. visitation and inspection rights;   6. keeping of
proper books in accordance with generally accepted     accounting principles;  
7. maintenance of properties;   8. performance of leases, related documents and
other material     agreements;   9. use of proceeds;   10. customary financial
and other reporting requirements;   11. additional credit parties; and   12.
clinical laboratory compliance programs.     (b) Negative Covenants –
Restrictions on:     1. liens;   2. indebtedness (with exceptions for the loans
incurred under the     Senior Credit Agreement), guaranties or other contingent
    obligations;   3. mergers and consolidations;   4. sale/leasebacks;   5.
sales, transfers and other dispositions of assets (other than sales     of
inventory in the ordinary course of business);   6. loans, acquisitions, joint
ventures and other investments;   7. repurchasing shares of capital stock
following the occurrence of     a default or an event of default under the
Bridge Loan     Documentation;   8. transactions with affiliates;   9. changing
the nature of its business; and   10.           changing fiscal year, accounting
policies or reporting practices.       (c) Financial Covenants – Maintenance of:
    1. a maximum ratio of total debt to EBITDA not to exceed (x)     3.50:1.00
through June 30, 2008 and (y) 3.25:1.00 thereafter, or     such other levels as
may be mutually agreed upon; and     2. a minimum ratio of EBITDA to interest
expense of at least     3.50:1.00, or such other levels as may be mutually
agreed upon.     The foregoing financial terms and ratios shall be defined in a
manner   satisfactory to the Borrower and the Lead Arranger. All of the
financial   covenants will be calculated on a consolidated and pro forma basis
and   for each consecutive four fiscal quarter period.   Events of Default:
Substantially similar to those contained in the Existing Credit Facilities  
(including with respect to grace periods, notice periods, monetary   thresholds
and other qualifications), including:

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  1.
failure to pay principal when due, or to pay interest or other
   
amounts within three business days after the same becomes due,
    under the Bridge Loan Documentation;     2.
any representation or warranty proving to have been materially
    incorrect when made or confirmed;     3.
failure to perform or observe covenants set forth in the Bridge
   
Loan Documentation within a specified period of time, where
   
customary and appropriate, after notice or knowledge of such
    failure;     4.
cross-defaults to other indebtedness in an amount in excess of
    $150,000,000;     5.
bankruptcy and insolvency defaults (with a grace period for
   
involuntary proceedings);
    6.
monetary judgment defaults in an amount in excess of
    $150,000,000;     7. impairment of Bridge Loan Documentation;     8. change
of ownership or operating control;     9. standard ERISA defaults and    
10.          
a material adverse change in the business, operations, properties
   
or conditions (financial or otherwise) of the Borrower and its
   
subsidiaries, taken as a whole, shall have occurred and be
    continuing on the 45th day following the Closing Date.   Expenses:
The Borrower shall pay all of the Administrative Agent’s and the Lead
 
Arranger’s due diligence, syndication (including printing, distribution
 
and bank meetings), transportation, computer, duplication, appraisal,
 
audit, insurance, consultant, search, filing and recording fees and all
 
other out-of-pocket expenses incurred by the Administrative Agent or the
 
Lead Arranger (including the fees and expenses of counsel for the Lead
 
Arranger), whether or not any of the transactions contemplated hereby
 
are consummated, as well as all expenses of the Administrative Agent in
 
connection with the administration of the Bridge Loan Documentation
 
(including, without limitation, fees and expenses incurred in connection
 
with the preparation of the Bridge Loan Documentation (and waivers or
 
amendments thereto) or the “work-out” or restructuring of the
  obligations). The Borrower shall also pay the expenses of the  
Administrative Agent, the Lead Arranger and the Bridge Lenders
 
(including the fees and expenses of counsel) in connection with the
  enforcement of any of the Bridge Loan Documentation.   Indemnity:
The Borrower will indemnify and hold harmless the Administrative
 
Agent, the Lead Arranger, each Bridge Lender and each of their affiliates

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  and their officers, directors, employees, agents and advisors from claims  
and losses relating to the Transaction or the Bridge Loan Facility, other   than
in the case of gross negligence, willful misconduct or bad faith of   the
indemnified party as finally determined by a court of competent   jurisdiction.
  Required Lenders: Bridge Lenders holding loans and commitments representing
more than   50% of the aggregate amount of loans and commitments under the  
Bridge Loan Facility (the “Required Lenders”).   Waivers &   Amendments:
Amendments and waivers of the provisions of the Bridge Loan   Documentation will
require the approval of the Required Lenders, except   that the consent of all
affected Bridge Lenders will be required with   respect to certain customary
issues, including but not limited to (i)   increases in commitment amounts, (ii)
reductions of principal, interest, or   fees, (iii) extensions of scheduled
maturities or times for payment, and  
(iv) releases of any material guarantee.
  Assignments and   Participations: Assignments may be non-pro rata and must be
to Eligible Assignees (to   be defined) and, in each case other than an
assignment to a Bridge   Lender or an assignment of the entirety of a Bridge
Lender’s interest in   the Bridge Loan Facility, in a minimum amount of
$5,000,000. Each   Bridge Lender will also have the right, without consent of
the Borrower   or the Administrative Agent, to assign (i) as security all or
part of its   rights under the Bridge Loan Documentation to any Federal Reserve
  Bank and (ii) all or part of its rights or obligations under the Bridge Loan  
Documentation to any of its affiliates. No participation shall include   voting
rights, other than for reductions or postponements of amounts   payable.  
Taxes: All payments are to be free and clear of any present or future taxes,  
withholdings or other deductions whatsoever (other than income taxes in   the
jurisdiction of the Bridge Lender’s applicable lending office). The   Borrower
will indemnify the Bridge Lenders and the Administrative   Agent for such taxes
paid by the Bridge Lenders or the Administrative   Agent.   Miscellaneous:
Standard yield protection (including compliance with risk-based capital  
guidelines, increased costs, payments free and clear of withholding taxes   and
interest period breakage indemnities), eurodollar illegality and   similar
provisions, defaulting lender provisions, “yank-a-bank”   provisions, waiver of
jury trial, and submission to jurisdiction provisions.   Governing Law: State of
New York.   Counsel for Morgan Stanley: Mayer, Brown, Rowe & Maw LLP.

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ANNEX I

DEBT RATINGS GRID

                 Applicable Percentage for Applicable Percentage for   Debt
Rating Eurodollar Loans Commitment Fee           >BBB+ from S&P/   .400%   .080%
  >Baa1 from Moody’s       >BBB but < BBB+ from S&P/   .500%   .100%   >Baa2 but
<Baa1 from Moody’s       >BBB- but <BBB from S&P/   .625%   .125%   >Baa3 but
<Baa2 from Moody’s       >BB+ but < BBB- from S&P/   .750%   .175%   >Ba1 but
<Baa3 from Moody’s       <BB+ or unrated by S&P/   1.250%   .250%   <Ba1 or
unrated by Moody’s    

If at any time there is a split in the Borrower’s Debt Ratings between S&P and
Moody’s, the applicable percentages shall be determined by the higher of the two
Debt Ratings (i.e. the lower pricing); provided that if the two Debt Ratings are
more than one level apart, the applicable percentage shall be based on the Debt
Rating which is one level higher than the lower rating.

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