**Exhibit10.13.1**

***EXECUTIONVERSION***
| **Fourth Amendment to Loan Documents** |   |  |
|----------------------------------------|--------|--|

 

**THIS FOURTH AMENDMENT TO LOAN DOCUMENTS**(this **“Amendment”**) is made as of October 31,2006, and is by and among **Bio-ReferenceLaboratories, Inc.** (“BRLI”), a Subsidiary of BRLI **MediLabs, Inc.** as the existing Subsidiary Party (“ExistingSubsidiary Borrower” and, collectively with BRLI, the “Existing Borrowers”),and a new Subsidiary of BRLI, **BRLI No. 2 AcquisitionCorp**., which is about to conduct business as Gene DX, Inc. (“BRLI-DX”),which is a new Subsidiary Party (Existing Subsidiary Borrower and BRLI-DX,collectively, the “Subsidiary Parties”) (BRLI and the Subsidiary Parties hereineach a “Borrower” and, collectively, “Borrowers”) the financial institutions whichare party hereto (collectively, the “Lenders” and individually a “Lender”) and **PNC BANK, NATIONAL ASSOCIATION**in its capacity as the agentfor the Lenders and as the sole Lender****(in each suchcapacity, the “Bank”).

**BACKGROUND**

A.            TheExisting Borrowers have executed and delivered to the Bank (or a predecessorwhich is now known by the Bank’s name as set forth above), one or morepromissory notes, letter agreements, loan agreements, security agreements,mortgages, pledge agreements, collateral assignments, and other agreements,instruments, certificates and documents, some or all of which are more fullydescribed on attached Exhibit A, which is made a part of this Amendment(collectively as amended from time to time, the “Loan Documents”) whichevidence or secure some or all of the Existing Borrowers’ obligations to theBank for one or more loans or other extensions of credit (the “Obligations”).

B.            TheExisting Borrowers and the Bank desire to amend the Loan Documents as providedfor in this Amendment.

**NOW, THEREFORE,** in considerationof the mutual covenants herein contained and intending to be legally boundhereby, the parties hereto agree as follows:

### 1.             Certain of the Loan Documents are amended as set forthin Exhibit A.  Any and all references toany Loan Document in any other Loan Document shall be deemed to refer to suchLoan Document as amended by this Amendment. This Amendment is deemed incorporated into each of the Loan Documents.Any initially capitalized terms used in this Amendment without definition shallhave the meanings assigned to those terms in the Loan Documents.  To the extent that any term or provision ofthis Amendment is or may be inconsistent with any term or provision in any LoanDocument, the terms and provisions of this Amendment shall control.

### 2.             (a) Each of the Existing Borrowers hereby certifiesthat: (a) all of its representations and warranties in the Loan Documents, asamended by this Amendment, are, except as may otherwise be stated in thisAmendment: (i) true and correct as of the date of this Amendment, (ii) ratifiedand confirmed without condition as if made anew, and (iii) incorporated intothis Amendment by reference.

### (b) Each of the Borrowershereby certifies that (i) no Event of Default or event which, with the passage oftime or the giving of notice or both, would constitute an Event of Default,exists under any Loan Document which will not be cured by the execution andeffectiveness of this Amendment, (ii) no consent, approval, order orauthorization of, or registration or filing with, any third party is requiredin connection with the execution, delivery and carrying out of this Amendmentor, if required, has been obtained, and (iii) this Amendment has been dulyauthorized, executed and delivered so that it constitutes the legal, valid andbinding obligation of each Borrower, enforceable in accordance with itsterms.  The Existing Borrowers confirmthat the

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### Obligations remain outstanding withoutdefense, set off, counterclaim, discount or charge of any kind as of the dateof this Amendment.

3.             Eachof the Borrowers hereby confirms that any collateral for the Obligations,including liens, security interests, mortgages, and pledges granted by theBorrowers or third parties (if applicable), shall continue unimpaired and infull force and effect, and shall cover and secure all of the Borrowers’existing and future Obligations to the Bank, as modified by this Amendment.

4.             Asa condition precedent to the effectiveness of this Amendment, the Borrowersshall comply with the terms and conditions (if any) specified in Exhibit A.

5.             Toinduce the Bank to enter into this Amendment, to the extent permitted by law,each of the Borrowers waives and releases and forever discharges the Bank andits officers, directors, attorneys, agents, and employees from any liability,damage, claim, loss or expense of any kind that it may have against the Bank orany of them arising out of or relating to the Obligations.  Each of the Borrowers further agrees to indemnifyand hold the Bank and its officers, directors, attorneys, agents and employeesharmless from any loss, damage, judgment, liability or expense (includingattorneys’ fees) suffered by or rendered against the Bank or any of them onaccount of any claims arising out of or relating to the Obligations.  Each of the Borrowers further states that ithas carefully read the foregoing release and indemnity, knows the contentsthereof and grants the same as its own free act and deed.

6.             ThisAmendment may be signed in any number of counterpart copies and by the partiesto this Amendment on separate counterparts, but all such copies shallconstitute one and the same instrument.  Delivery of an executed counterpart of a signature page to thisAmendment by facsimile transmission shall be effective as delivery of amanually executed counterpart.  Any partyso executing this Amendment by facsimile transmission shall promptly deliver amanually executed counterpart, provided that any failure to do so shall notaffect the validity of the counterpart executed by facsimile transmission.

7.             ThisAmendment will be binding upon and inure to the benefit of each Borrower andthe Bank and their respective heirs, executors, administrators, successors andassigns.

8.             ThisAmendment has been delivered to and accepted by the Bank and will be deemed tobe made in the State where the Bank’s office indicated in the Loan Documents islocated.  This Amendment will beinterpreted and the rights and liabilities of the parties hereto determined inaccordance with the laws of the State where the Bank’s office indicated in theLoan Documents is located, excluding its conflict of laws rules.

9.             Exceptas amended hereby, the terms and provisions of the Loan Documents remainunchanged, are and shall remain in full force and effect unless and untilmodified or amended in writing in accordance with their terms, and are herebyratified and confirmed.  Except asexpressly provided herein, this Amendment shall not constitute an amendment,waiver, consent or release with respect to any provision of any Loan Document,a waiver of any default or Event of Default under any Loan Document, or awaiver or release of any of the Bank’s rights and remedies (all of which arehereby reserved).  **Each of theBorrowers expressly ratifies and confirms the waiver of jury trial provisionscontained in the Loan Documents.**

[Signature page follows.]

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**WITNESS** the due execution of this Fourth Amendmentto Loan Documents as a document under seal as of the date first written above.
| ATTEST:    | ** **     |   | **BIO-REFERENCE LABORATORIES, INC.** |                              |
|------------|----------------|--------|--------------------------------------|-----------------------------------|
|       | ** **     |   | ** **                           |                              |
|       | ** **     |   | ** **                           |                              |
| By:        | /S/ Sam Singer |   |                                 | By:                               | /S/ Marc D.  Grodman |   |
| Name:      | SAM SINGER     |   |                                 | Name:                             | MARC D. GRODMAN | (SEAL) |   |
| Title:     | Secretary      |   |                                 | Title:                            | President |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
| ATTEST:    | ** **     |   |                                 | **MEDILABS, INC.,**               |   |
|       |           |   |                                 |                              | a Subsidiary Party |   |
|       |           |   |                                 |                              |   |   |
|       |           |   |                                 |                              |   |   |
| By:        | /S/ Sam Singer |   |                                 | By:                               | /S/ Marc D.  Grodman |   |   |
| Name:      | SAM SINGER     |   |                                 |                              |   |   | (SEAL) |   |
| Title:     | Secretary      |   |                                 | Name:                             | MARC D. GRODMAN |   |   |
|       |           |   |                                 |                              | Title: | President |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
| ATTEST:    | ** **     |   |                                 | **BRLI NO. 2 ACQUISITION CORP.,** |   |
|       |           |   |                                 |                              | a Subsidiary Party |   |
|       |           |   |                                 |                              |   |   |
|       |           |   |                                 |                              |   |   |
| By:        | /S/ Sam Singer |   |                                 | By:                               | /S/ Marc D.  Grodman |   |   |
| Name:      | SAM SINGER     |   |                                 |                              |   | (SEAL) |   |
| Title:     | Secretary      |   |                                 | Name:                             | MARC D. GRODMAN |   |   |   |
|       |           |   |                                 |                              | Title: | President |   |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
|       |           |   |                                 |                              |   |   |   |   |   |
| ** ** |           |   |                                 |                              | **PNC BANK, NATIONAL ASSOCIATION** |   |
| ** ** |           |   |                                 |                              | ** ** |   |
| ** ** |           |   |                                 |                              | ** ** |   |
|       |           |   |                                 | By:                               | /S/ Parameswar  Sivaramakrishnan |   |   |
|       |           |   |                                 |                              |   |   |   | (SEAL) |   |
|       |           |   |                                 |                              | Name: | PARAMESWAR SIVARAMAKRISHNAN |   |   |
|       |           |   |                                 |                              | Title: | Vice President |   |   |
|            |                |        |                                      |                                   |  |  |  |  |  |  |  |  |  |  |  |

 

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