**First
                South********
              ***Farm
                Credit***
            713
                South Pear Orchard Road, Suite 102 • Ridgeland, MS 39157
              P.O.
                Box 1709 • Ridgeland, MS 39158-1709
              (601)
                977-8353 • fax (601) 977-8358 •www.firstsouthfarmcredit.com





September
      19, 2006





VIA
      E-MAIL





Mr.
      Darrell Dubroc, CEO


Vanguard
      Synfuels, LLC


P.0.
      Box
      399


Pollock,
      LA 71467





**Re:**
            **Vanguard
                Synfuels, LLC (Vanguard') Loans with First South Farm Credit, ACA
                (“First
                South”)**





Gentlemen:





First
      South Farm Credit, ACA (“First South”) has considered the request to release the
      existing six individual guarantors (the “Guarantor”) for Vanguards loans, and
      accept a guarantee of Diametrics Medical, Inc. (“DMED”). This is to advise that
      First South agrees to release the (six individual) Guarantors provided all ** of
      the
      following conditions are met, satisfied, and delivered to First South, on or
      before 4:00 p.m. CDT, Friday, September 29, 2006.





(1)  DMED
      acquires 100% of the membership/ownership interest in Vanguard Synfuels, LLC,
      and satisfactory evidence thereof is furnished to First South;





(2)  First
      South is furnished with a copy of the Articles and By-Laws of DMED, as amended,
      to date, along with a certificate of good standing from the State of its
      incorporation;





(3)  Furnish
      evidence satisfactory to First South, in its sole discretion, of the cash
      investment of $7,000,000.00 in equity in DMED;





(4)  Furnish
      a
      certified resolution of the board of directors of DMED acknowledging that
      Vanguard is a 100% owned subsidiary of DMED and that it serves a legitimate
      business purpose for DMED to unconditionally and in solido (jointly and
      severally) with Vanguard, guarantee the timely payment and performance of all
      indebtedness and obligations of Vanguard to First South, which resolution would
      also authorize a duly designated (named) officer to execute the continuing
      guaranty agreement in the form of Exhibit “A” hereto (the “Guaranty”) for any
      and all of the present and/or future indebtedness and obligations of Vanguard
      to
      First South. First South would also need to be furnished with Vanguard’s Board
      of Managers/Directors consent resolution authorizing a named official to enter
      into the amendment to the loan agreement, under such terms and conditions as
      said official deems appropriate.





(5)  DMED
      would execute and deliver the Guaranty to First South.





(6)  Vanguard
      and First South would execute and deliver a First Amendment to Loan Agreement
      in
      the form of Exhibit 'B' attached hereto.









(7)  Upon
      timely satisfaction of the above conditions, First South will promptly (within
      2
      business days) deliver to an agent for Vanguard, DMED and each of the Guarantors
      (“Agent”), as set forth in the First Amendment to Loan Agreement, the original
      of each of the existing Guarantors guaranty agreements, each marked “Cancelled
      and Released.” The delivery of the original guaranty agreements will be made by
      sending each of the six original guaranty agreements by U.S Certified Mail
      addressed to Agent as set forth in the First Amendment to Loan Agreement.





*****************************************************************************





First
      South’s agreement to release the existing Guarantors is further conditioned upon
      all of the documents, documentation and supporting evidence required above
      to be
      satisfactory in form and substance to First South, in its sole discretion,
      and
      Vanguard shall promptly (on or before September 29, 2006) pay all costs and
      expenses related to the negotiation of this agreement and finalizing the
      proposed transaction, including paying First South’s attorney fees of $3,000.00.
      Failure to timely pay said sums shall be an Event of Default under the Loan
      Agreement. Finally, this proposal will expire and terminate unless Vanguard
      and
      DMED both accept this proposal in writing and return their signed acceptance
      to
      First South or on before 4:00 p.m. CDT Wednesday, September 20, 2006. Fax or
      electronic signatures will be deemed acceptable as originals, and the acceptance
      may be executed in multiple counterparts.




Very
                truly yours,
              
              **FIRST
                  SOUTH FARM CREDIT, ACA**/s/
                Timothy C. DupuyTimothy
                C. Dupuy, Division Vice President








cc:
            John
                Hurt, via email:jhurt@firstsouthfarmcredit.comCecil
                Corbello, via email:ccorbello@,firstsouthfarmcredit.comA.
                Michael Dufilho, attorney, via email:michael.dufilho@taylorporter.com






AGREED
                TO AND ACCEPTED:
              VANGUARD
                SYNFUELS, LLC
            
            
            AGREED
                TO AND ACCEPTED:
              DIAMETRICS
                MEDICAL, INC.By:/s/
                Darrell J. Dubroc
            
            
            By:/s/
                W. Bruce Comer IIIName:Darrell
                J. Dubroc
            
            
            Name:W.
                Bruce Comer IIITitle:President
              Date:September
                20, 2006
            
            
            Title:Chief
                Executive Officer
              Date:September
                20, 2006





**EXHIBIT
      "A"**


**CONTINUING
      GUARANTY**





Debtor:  Vanguard
      Svnfuels, LLC


Pollock,
      Louisiana





In
      consideration of FIRST SOUTH **** FARM
      CREDIT, ACA ("Creditor") making loans or advances or otherwise giving credit
      to
      the above named debtor ("Debtor"), as Creditor and Debtor may from time to
      time
      agree upon, the undersigned guarantor (“Guarantor”), does hereby unconditionally
      and in solido with Debtor, guarantee to Creditor, its successors and assigns,
      and all future holder or holders of this Continuing Guaranty, which is hereby
      declared to be transferable, the prompt payment of all debts, obligations,
      and
      liabilities, whether direct, indirect, absolute, contingent, secured, or
      unsecured, (hereinafter collectively referred to some times as “Obligations”)
      which Debtor may now or at any time, or times, hereafter owe, or be liable
      to
      pay to Creditor, and Guarantor agrees to pay the same promptly when due and
      at
      all times thereafter, without notice or demand. Should Debtor be or become
      insolvent, then Guarantor agrees to pay all Obligations forthwith whether then
      due or not due.





Creditor
      may sell, pledge, assign, discount, rediscount, surrender, compound, release,
      renew, extend, forebear, alter, exchange, or otherwise deal with and/or dispose
      of any and all property, securities, collateral, endorsements and guaranties
      now
      or hereafter held by said Creditor as security, indemnity, or otherwise, upon
      such terms and conditions as Creditor in its sole discretion may deem advisable,
      and Creditor may, from time to time, make such changes in, renewals and
      extensions of time, mode and terms of payment of said Obligations of Debtor,
      and
      of the time, mode and terms of payment of all or any endorsements and guaranties
      of said Obligations made by others, as Creditor in its sole discretion may
      deem
      advisable; all without in any way affecting, limiting, or ****** prejudicing
      the Creditor’s rights or the Guarantor’s liability under this Continuing
      Guaranty. Creditor is hereby irrevocably authorized and empowered at any and
      all
      times to impute or apply, as it may see fit, any payment or payments which
      may
      be made by Debtor or by others on Debtor’s Obligations.





This **** guaranty
      shall be a continuing guaranty, and shall remain in full force and effect until
      terminated by the Creditor’s receipt of 30 days prior written notice of its
      termination; but such termination shall not affect or impair said Guarantor’s
      liability hereunder as to any Obligations of the Debtor existing on the
      effective date of such termination, or as to any subsequent modifications,
      renewals, extensions or changes in the form or evidence of said existing
      Obligations, whether such Obligations are matured or not upon the effective
      date
      of termination. Such termination shall not affect Creditor’s right to release,
      modify or otherwise change the security or collateral Creditor may hold, or
      to
      release or modify the liability of any of the undersigned signor(s) or of any
      other surety or guarantor of Debtor’s Obligations it being agreed that Creditor
      may take such action in regard to such security or collateral or sureties or
      guarantors as Creditor in its sole discretion may deem advisable. It is further
      agreed that upon receipt of notice of termination, Creditor is under no
      obligation to take any steps to enforce or collect Debtor’s Obligations and
      Creditor’s failure to take any steps to enforce or collect Debtor’s Obligations
      shall not affect Guarantor’s liability herein for all Obligations of Debtor to
      Creditor as of the effective date of the termination or as to any renewals,
      extensions or modifications or changes in the form of evidence of those
      Obligations.





It
      is
      further agreed that the Guarantor’s liability under this Continuing Guaranty
      shall not be affected or impaired by any failure of Creditor to realize for
      any
      reason, upon any property, securities, collateral, endorsements or guaranties,
      nor by any alteration of any contract express or implied, nor by any change
      in
      Debtor, by death, dissolution, withdrawal, or otherwise, but Guarantor agrees
      to
      pay in any event the entire ultimate balance of Debtor’s Obligations (including
      principal, interest, attorney fees and costs of collection), now or hereafter
      due or owing by Debtor to Creditor. Creditor shall, at no time, **** and
      under
      no circumstances, be bound to resort to any collateral, securities, endorsements
      or guaranties now or hereafter held by Creditor as security, indemnity, or
      otherwise, the undersigned Guarantor being bound to pay by this continuing
      Guaranty to the same extent as and in solido with Debtor, and **** said
      Guarantor specifically waives the right and the benefits of demanding division
      and discussion.









Guarantor
      hereby waives any formal acceptance and waives notice of the acceptance of
      this
      Continuing Guaranty by Creditor, and Guarantor also waives notice of any loans,
      advances, discounts, or credits that may be **** made
      to
      Debtor, it being the intention of Guarantor that Creditor shall have the right
      to make loans, advances, and discounts, and to give credit to the Debtor on
      the
      faith hereof without notice to Guarantor.





Guarantor
      hereby also waives notice of all defaults by said Debtor or others, and
      of **** all
      things now existing, or hereafter occurring in any dealings between or among
      Creditor, Debtor and others.





The
      liability of Guarantor for payment shall be in solido with Debtor, and as
      to **** each
      undersigned Guarantor, if there be more than one, each shall be and shall,
      remain obligated to Creditor in the full amount set forth herein. Creditor
      may
      obtain other guarantees for Debtor in whole or in part, and may release the
      guarantors or any of them in whole or in part without affecting the liability
      of
      any Guarantor under this Continuing Guaranty. Each of the undersigned signers
      waives and renounces as to each other and any other guarantors and/or sureties
      of Debtor’s Obligations, the right of demanding, and the benefits of, division
      and discussion.





This
      agreement, regardless where actually signed, shall be construed under and
      governed by the laws of the State of Louisiana and Guarantor consents to the
      personal jurisdiction of any federal or state court in Louisiana, if suit is
      filed to enforce this guaranty agreement.





In
      the
      event this Continuing Guaranty is referred to an attorney at law for collection
      by suit, or otherwise, Guarantor will also owe and pay reasonable attorney
      fees
      relating to such collection efforts.





THUS
      DONE, READ AND SIGNED in Los Angeles, California, on the 20 th day of
      September, 2006.




PAYMENT
                GUARANTEED
                
                GUARANTOR:
                Diametrics
                  Medical, Inc./s/
                W. Bruce Comer IIIW.
                Bruce Comer III
              CEO,
                Duly Authorized






WITNESSES:





/s/
      Tiffanie Baker





Tiffanie
      Baker





/s/
      Heng
      Chuk





Heng
      Chuk







**EXHIBIT
      "B"**


**FIRST
      AMENDMENT TO LOAN AGREEMENT**





**WHEREAS** ,
      Vanguard Synfuels, LLC ("Vanguard") entered into a Loan Agreement with First
      South Farm Credit, ACA ("First South") dated January 12, 2006, (the "Original
      Agreement") and in which the six individual existing guarantors of the
      liabilities and obligations of Vanguard to First South intervened;





**WHEREAS** ,
      as part
      of the sale of 100% membership interest in Vanguard to Diametrics Medical,
      Inc.
      ("DMED"), Vanguard has requested that First South release the original
      guarantors and accept DMED as a successor guarantor;





**WHEREAS** ,
      First
      South has agreed to that release conditioned upon certain terms and conditions,
      including the execution of this First Amendment to Loan Agreement (the "Amended
      Agreement");





**NOW,
      THEREFORE, IT IS HEREBY AGREED** as
      follows:





1.
            Paragraph
                V, Special Conditions, of the original agreement is hereby amended
                to read
                in its entirety as follows:





**V.**
            **Special
                Conditions**





In
      the
      event of any conflict between the terms of this Loan Agreement and any of the
      other Loan Documents, the terms of such other Loan Documents shall control.
      Borrower and Lender agree that this Loan Agreement shall be governed by the
      laws
      of the jurisdiction listed in the address of Lender as shown on the first page
      of this Loan Agreement. The Loan is further subject to the following terms,
      covenants and special conditions.





**Conditions
      Precedent:** The
      following shall be conditions precedent to any obligation of Lender to make
      the
      Loan to Borrower:





|1. | Lender
              shall have a first priority perfected lien and security interest in
              all
              Collateral at the time of Closing.
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------------




|2. | Execution
              and delivery of all Loan Documents, and the same shall be in full force
              and effect.
|-- | -------------------------------------------------------------------------------------------------------------------------




|3. | Borrower
              shall have obtained and furnished to Lender environmental audit(s)
              covering all Collateral, the results of which shall be satisfactory
              to
              Lender in its sole discretion. Lender shall also have received, to
              its
              satisfaction, evidence of Borrower's compliance with all applicable
              environmental laws, regulations, policies, orders, and permitting and
              licensing requirements to which Borrower, its operations and the
              Collateral may be subject. Borrower shall provide Lender an Environmental
              Hazards Assessment (Form ENV-1) covering the Real
              Property.
|-- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|4. | Lender
              shall be provided mortgage title insurance covering the Real Property
              in
              the amount of the Loan containing no exceptions from coverage except
              those
              which are acceptable to Lender and issued by a title insurance company
              acceptable to Lender.
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|5. | Lender
              shall be provided such information and documentation relating to the
              Real
              Property and its acquisition as Lender, in its discretion, may
              require.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------








|6. | Lender
              shall receive an opinion of legal counsel for Borrower certifying the
              good
              standing of Borrower and its authority and capacity to enter into the
              transaction contemplated herein, and such other matters as Lender may
              require, all in form and content satisfactory to
              Lender.
|-- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|7. | A
              FEMA Standard Flood Hazard Determination is to be completed. If real
              estate is determined to be in a flood zone, Borrower will provide evidence
              of flood insurance.
|-- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




**Additional
      Covenants**





|· | Existing
              and future indebtedness and advances ("Obligations") to Vanguard by
              its
              member, Diametrics Medical, Inc. ("DMED") will be subordinate to First
              South's debt, with no payments allowed on these Obligations without
              the
              prior written consent of First South;
|- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|· | The
              interest paid on the notes to the members will not be greater than
              the
              rate of interest paid by Vanguard on the First South debt;
|- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|· | Provide
              written notice, providing details of transaction, prior to pledging
              assets
              to or borrowing money from another
              lender;
|- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|· | Provide
              evidence of insurance, with First South named as mortgage/loss payee
              on
              the appropriate policies.
|- | ---------------------------------------------------------------------------------------------------------------------------------------------------




|· | Advances
              on the proposed revolving line of credit will not exceed $500,000 from
              the
              closing date through February 28, 2006, with additional advances to
              be at
              the discretion of First South.
|- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




**Financial
      Covenants:** The
      Borrower warrants and covenants to the following:





|· | Achieve
              by FYE 12/31/06 and maintain thereafter a minimum working capital position
              of $750,000;
|- | ---------------------------------------------------------------------------------------------------------------------------




|· | Achieve
              by FYE 12/31/06 and maintain thereafter an excess of total assets over
              total liabilities of not less than
              $1,500,000;
|- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------




|· | Maintain
              the Cash Flow Coverage Ratio (defined as the ratio of net profit after
              taxes plus depreciation minus capital expenditures minus salary
              distributions to key employees minus distributions to stockholders
              on
              their equity investment to the current portion of long-term debt) to
              be no
              less than 1.25 to 1.00, to be measured at each fiscal year
              end.
|- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




**New
      Covenants**





|1. | Vanguard
              shall furnish, and/or cause DMED to furnish, quarterly internal,
              consolidated and consolidating financial statements of DMED and Vanguard,
              certified by the chief financial officer (CFO) of DMED and of Vanguard,
              on
              or before 30 days after each calendar quarter, which would show the
              separate financial status for each entity as well as the consolidated
              status and which financial statements would include a balance sheet,
              a
              statement of contingent liabilities and statement of income and expense
              for the prior quarter and year to date. Vanguard shall furnish or cause
              DMED to furnish directly to First South any reports, etc. filed by
              DMED
              with the SEC and furnish or cause DMED to furnish directly to First
              South
              any and all notices, reports sent to shareholders of DMED, each of
              said
              notices, reports, etc. to be furnished contemporaneously with the filing
              of such matters and/or sending such notices. Vanguard shall furnish,
              or
              cause DMED to furnish, DMED’s annual audited financial statements within
              120 days of each fiscal year end;
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------








|2. | Vanguard
              agrees and shall cause DMED to agree that First South directly or through
              its agents, may inspect the business, assets, books and records concerning
              DMED and/or Vanguard upon furnishing two business days prior written
              notice to DMED and/or Vanguard, as applicable, and Vanguard furnish,
              or
              cause DMED to furnish, as applicable, an officer to cooperate and work
              with First South and/or its agency reviewing any such books and records
              and/or the business and/or assets of Vanguard and/or DMED. All such
              reviews will be conducted during normal business hours.
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|3. | Vanguard
              will cause DMED to execute an unconditional, in solido continuing guaranty
              agreement of all of the debts and obligations of Vanguard, whether
              present
              or future, to First South.
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|4. | It
              is further agreed that in addition to any other events of default as
              contained in the original Loan Agreement, (i) if there is a default
              by
              Vanguard, complying with the terms and conditions of this Amended
              Agreement, or causing DMED to fully and timely comply with the terms
              and
              conditions of this Amended Agreement, this shall constitute an additional
              event of default.
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|5. | It
              is hereby agreed that the original six individual existing guarantors
              will
              be released and their original guaranty agreements will be marked
              "cancelled" and promptly sent by U.S Certified Mail to Darrell Dubroc,
              as
              agent for the original six guarantors, addressed as follows: Darrel
              Dubroc, P.O. Box 399, Pollock, LA 71467.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------




|6. | Vanguard
              further agrees that if, and when, DMED changes its state of incorporation
              and/or amends its name, Vanguard shall furnish or cause DMED to promptly
              (within three (3) business days thereof), furnish copies of DMED's
              revised
              organizational documents as filed with the Secretary of State of the
              state
              of its then incorporation and if DMED's name is amended in, under the
              amended name DMED shall ratify and confirm under its amended name DMED's
              obligation under the then existing continuing guaranty agreement
              previously executed by DMED.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



**VI.**  **No
      Novation.** It
      is
      expressly agreed that this First Amendment does not constitute a novation of
      Vanguard's existing obligations and/or any collateral and security for those
      obligations, except for the release of the original individual guarantors.
      Except as expressly and specifically modified herein, all of the terms and
      provisions of the Original Agreement remain in full force and
      effect.





**VII.**   This
      agreement may be executed in multiple originals and fax and/or electronic
      signatures shall be deemed effective as originals.




VANGUARD
                SYNFUELS, L.L.C.By:
            /s/
              Darrell J. DubrocName:
            Darrell
                J. DubrocDate:
            September
                20, 2006  FIRST
                    SOUTH FARM CREDIT, ACABy:Name:Date:


**[FirstSouth
      Letterhead]**







February
      28, 2007





Attn:  Mr.
      Darrell Dubroc, President


Vanguard
      Synfuels, L.L.C.


429
      Murray Street, Suite 700


Alexandria,
      Louisiana 71301


Tel:
      (318) 442-8730


Fax:
      (310) 670-4107





**Re:**  **Limited
      Waiver**




Gentlemen:





We
      would
      like to have the opportunity to further review and discuss with you the
      financial information, business prospects and capital needs of Vanguard
      Synfuels, L.L.C. and Allegro Biodiesel Corporation (“Allegro”). Therefore, to
      facilitate such discussions, we are providing you with a limited waiver to
      certain specified Events of Default under the Loan Agreement by First South
      Farm
      Credit, ACA (“FirstSouth”) and Vanguard, dated January 12, 2006 (and as amended
      September 19, 2006), for a period of time as set forth herein.





Through
      to the date of July 1, 2007, we hereby waive the following Events of Default:





(a)
            The
                failure by Vanguard to maintain a Cash Flow Coverage Ratio of at
                least
                1.25 to 1.00 as of December 31, 2006, and





(b)
            The
                failure by Vanguard to maintain a working capital position of
                $750,000.





Any
      further waiver extending beyond July 1, 2007 shall be subject to our review
      of
      your financial information and discussions with you, which shall only be granted
      at our sole discretion.





Vanguard
      represents to FirstSouth that, after giving effect to the waiver provided above,
      no other Event of Default shall have occurred and be continuing on the date
      hereof, nor shall result from the consummation of the transactions contemplated
      herein. In addition, the Loan Agreement, as amended, and each of the other
      Loan
      Documents shall otherwise remain in full force and effect in accordance with
      their respective terms.





Please
      indicate your acceptance by signing below. I look forward to working with you
      on
      Vanguard and Allegro’s capital needs.









Yours
                sincerely,
              
              **FIRST
                  SOUTH FARM CREDIT, ACA**By:
            /s/
              Timothy C. DupuyTimothy
                C. Dupuy
              Division
                Vice President




Agreed
        to
        and accepted:
  **VANGUARD
          SYNFUELS, L.L.C.**





By:/s/ Darrell J. DubrocName:Darrell J. DubrocTitle:President







**ALLEGRO
      BIODIESEL CORPORATION**


By:/s/ Heng ChukName:Heng ChukTitle:Chief Financial Officer