Document:

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                                                                   Exhibit 10.51

                                 LOAN AGREEMENT

      This LOAN AGREEMENT (this "Agreement") is made and entered into by and
between DREW SCIENTIFIC, INC., a Texas corporation ("Borrower"), and TEXAS
MEZZANINE FUND INC., a Texas corporation ("Lender").

      Borrower has applied to Lender for a loan in the principal amount of Five
Hundred Fifty-Eight Thousand and No/100 Dollars ($558,000.00) (the "Loan"). In
consideration of the mutual covenants and agreements herein contained, Lender
and Borrower agree as follows:

                                   WITNESSETH:

      1.00. Definitions The terms used in this Agreement shall have the
following meanings:

      1.01. Casualty Insurance Policies shall mean fire insurance, comprehensive
property damage, public liability, worker's compensation, and other insurance
deemed necessary or otherwise required by Lender. Each of the Casualty Insurance
Policies shall name Lender as an additional insured and shall be specifically
endorsed to provide for at least thirty (30) days prior written notice to Lender
of cancellation or modification thereof. The insurance provisions of this
Agreement are cumulative of any insurance provisions contained in the Security
Instrument.

      1.02. Collateral shall mean the Personal Property and the benefits payable
pursuant to an assignment of Life Insurance Policy.

      1.03. Governmental Authority shall mean any and all courts, boards,
agencies, commissions, offices or authorities of any nature whatsoever for any
governmental unit (federal, state, county, district, municipal, city or
otherwise) whether now or hereafter in existence.

      1.04. Guarantor shall mean, jointly and severally, Keith Raymond Drew and
Drew Scientific Group, PLC.

      1.05. Guaranty shall mean a guaranty agreement duly executed by the
Guarantor, whereby the Guarantor, primarily and unconditionally, guarantees to
Lender payment of the Loan and performance of Borrower's obligations under the
Loan Documents.

      1.06. Legal Requirements shall mean (a) any and all present and future
judicial decisions, statutes, rulings, rules, regulations, permits, certificates
or ordinances of any Governmental Authority in any way applicable to Borrower,
any guarantor or the Collateral, including, but not limited to, those respecting
the ownership, use, occupancy, possession, operation, maintenance, alteration,
repair or reconstruction thereof, (b) Borrower's organizational documents, (c)
any and all leases and other contracts (written or oral) of any nature to which
Borrower or any guarantor may be bound, and (d) any and all restrictions,
reservations, conditions, easements or other covenants or agreements of record
affecting the Collateral.

      1.07. Life Insurance Policy shall mean a life insurance policy upon Keith
Raymond Drew, with an insurance company satisfactory to Lender, in an amount of
not less that $558,000.00 for such policy. The Life Insurance Policy shall be
specifically endorsed to provide at least thirty (30) days prior written notice
to Lender of cancellation or modification thereof.

      1.08. Loan Documents shall include this Agreement, the Note (including all
renewals, extensions, modifications and rearrangements thereof), the Security
Instrument and all other instruments contemplated to be executed pursuant to or
in connection with the Loan.

      1.09. Note shall mean that certain Promissory Note in the stated principal
amount of $558,000.00, in the form and substance as prescribed by Lender, and
all renewals, extensions and rearrangements thereof or substitutions

LOAN AGREEMENT - Page 1

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therefore, permitted by the Lender, duly executed by Borrower. The principal of
and interest on the Note shall be due and payable in accordance with the terms
and conditions set forth in the Note and in this Agreement.

      1.10. Personal Property shall mean all of the following property Borrower
now or later owns or has an interest in, wherever located:

            (a) All Accounts, Chattel Paper, contract rights, Documents,
      Instruments, Deposit Accounts and General Intangibles.

            (b) All Equipment and Fixtures.

            (c) All Inventory.

            (d) All Goods, Instruments, Documents, Investment Property, money or
      other property which are now or later in possession or control of Lender,
      or as to which Lender now or later controls possession.

            (e) All additions, accessions, attachments, replacements,
      substitutions, amendments, modifications, extensions, renewals,
      enlargements, products, Proceeds, income, interest, profits and
      distributions of or relating to the foregoing.

            (f) All books of account, customer lists and other Records relating
      in any way to the foregoing.

All terms capitalized above shall have the meanings assigned to them in the
Uniform Commercial Code of the State of Texas.

      1.11. Security Agreement shall mean that certain Security Agreement
covering the Personal Property and securing the Note and all other debts,
obligations and liabilities of every kind and character of Borrower now or
hereafter existing in favor of Lender, duly executed by Borrower and such others
(if any) as shall be required to create a security interest in the Personal
Property.

      1.12. Security Instrument shall mean the Security Agreement.

      2.00. LOAN COMMITMENT AND REPAYMENT. Subject to the terms and provisions
of this Agreement:

      2.01. Loan Commitment. Lender agrees to loan Borrower, and Borrower agrees
to borrow from Lender, the amount of Five Hundred Fifty-Eight Thousand and
No/100 Dollars ($558,000.00). Lender agrees to make the Loan to Borrower in
advances subject to and in accordance with the terms and conditions of this
Agreement. Lender's commitment to lend shall expire and terminate (a) on April
30, 2004; or (b) at Lender's option in the event of an Event of Default. The
Loan is not revolving. An amount repaid may not be reborrowed. Interest on the
sums advanced under the Loan shall accrue at the rate of 8.0% per annum (subject
to annual adjustment as provided for in the Note) and shall be calculated at a
daily rate equal to 1/360th of the annual percentage rate, based on the actual
number of days elapsed. Borrower shall execute and deliver to Lender the Note to
evidence Borrower's obligation to repay the Loan.

      2.02. Security, Payment of the indebtedness evidenced by the Note and the
other Loan Documents shall be secured by the Security Instrument and the liens,
security interests and collateral assignments created or evidenced by the other
Loan Documents and guaranteed by the Guarantor.

      2.03. Required Documentation. Borrower and Lender agree that prior to any
advance of Loan proceeds, Lender shall have received (a) the Note, the Security
Instrument and all other Loan Documents appropriately executed by Borrower and
all other proper parties, (b) a waiver of any landlord's lien upon any of the
Personal Property, (c) an agreement with the holder of any lien or security
interest on the Collateral (without hereby implying the consent of Lender to the
existence or creation of a such lien or security interest) regarding the
priority of liens and security interests on the Collateral, (d) a subordination
agreement from Guarantors regarding the payment of any debts due by Borrower,

LOAN AGREEMENT - Page 2

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and (e) as part of the consideration for making the Loan, a revenue
participation agreement granting Lender the right to participate in certain
revenues generated by Borrower's business operations.

      2.04. Conditions Precedent To Loan Advances.

            (a) At least five (5) business days before the requested date of an
      advance of Loan proceeds, Borrower shall deliver an Advance Request to
      Lender. Borrower shall be entitled to an advance only in an amount
      approved by Lender in accordance with the terms of this Agreement and the
      Loan Documents. An "Advance Request" means a properly completed and
      executed written application by Borrower to Lender, in a form approved by
      Lender, setting forth the amount of Loan proceeds desired, together with
      such schedules, affidavits, statements, invoices, bills, and other
      documents, certificates and information required by Lender. Lender shall
      make the requested advance to Borrower on a business day within five (5)
      business days after satisfaction of all applicable conditions of this
      Agreement and the Loan Documents. Lender's obligation to make any advances
      under this Agreement and the other Loan Documents shall be subject to the
      conditions precedent that, as of the date of such advance and after giving
      effect thereto (a) all representations and warranties made to Lender by
      Borrower and any of the guarantors in this Agreement and the other Loan
      Documents shall be true and correct, as of and as if made on the date of
      such advance, (b) no material adverse change in the financial condition of
      Borrower or any of the guarantors since the effective date of the most
      recent financial statements furnished to Lender by Borrower or any of the
      guarantors shall have occurred and be continuing, and (c) no event has
      occurred and is continuing, or would result from the requested advance,
      which with notice or lapse of time, or both, would constitute an Event of
      Default, Each Advance Request, and Borrower's acceptance of any advance,
      shall be deemed to ratify and confirm that all representations and
      warranties in the Loan Documents remain true and correct as of the date of
      the Advance Request and the advance, respectively. Advances may also be
      made, in addition to other methods contemplated herein, at Lender's
      option, by direct or joint check payment to any or all vendors or other
      persons entitled to payment for work or services performed or materials or
      goods furnished in connection with the Advance Request.

            (b) Borrower and Lender agree that the first advance of Loan
      proceeds hereunder shall consist of (i) the amounts necessary to renew and
      extend the unpaid indebtedness evidenced by that certain Promissory Note
      dated August 3,1999, in the stated principal amount of $500,000.00,
      executed by MWI, Inc. (now known as Borrower pursuant to those certain
      Articles of Amendment to the Articles of Incorporation of MWI, Inc. filed
      with the Texas secretary of State's Office on November 7, 2002) and
      payable to the order of the Lender, and (ii) an amount not to exceed
      $245,000.00. Borrower and Lender further agree that the second advance of
      Loan proceeds hereunder shall be in an amount not to exceed $100,000.00.
      Subsequent advances of Loan proceeds hereunder shall be made pursuant to
      Section 2.04(a) above.

      3.00. REPRESENTATIONS AND WARRANTIES OF BORROWER. Borrower represents and
warrants that:

      3.01. Organization. Borrower is a corporation duly incorporated, validly
existing and in good standing under the laws of the State of Texas and all other
states where it is doing business, and has all requisite power and authority to
execute and deliver this Agreement and the other Loan Documents.

      3.02. Due Execution of Loan Documents. This Agreement, the Note, the
Security Instrument and the other Loan Documents have been or will be duly
executed, issued and delivered by Borrower and constitute or, when executed and
delivered to Lender, will constitute valid and legally binding obligations of
Borrower, enforceable in accordance with their respective terms.

      3.03. Consent Not Required. No consent of any person and no consent,
license, approval or authorization of, or registration or declaration with, any
governmental body, authority, bureau or agency is required in connection with
the execution and delivery of this Agreement, the Note, the Security Instrument
and the other Loan Documents to which Borrower is a party.

LOAN AGREEMENT - Page 3

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      3.04. No Conflict. The execution and delivery of this Agreement, the Note,
the Security Instrument and the other Loan Documents, the consummation of the
transactions contemplated therein, and the compliance by Borrower with this
Agreement, the Note, the Security Instrument and the other Loan Documents, will
not conflict with, violate or result in a breach of or constitute (with due
notice or lapse of time, or both) a default under, any Legal Requirement or
result in the creation or imposition of any lien, charge or encumbrance of any
nature whatsoever upon any of Borrower's or any of any guarantor's property
other than the lien and security interest created by the Loan Documents.

      3.05. No Pending or Threatened Litigation. There are no actions, suits or
proceedings pending, or to the knowledge of Borrower, threatened against or
affecting Borrower, any guarantor or the Collateral.

      3.06. Financial Matters. Borrower is solvent, is not bankrupt and has no
outstanding liens, suits, garnishments, bankruptcies or court actions which
could render Borrower insolvent or bankrupt. There has not been filed by or
against Borrower a petition in bankruptcy or a petition or answer seeking an
assignment for the benefit of creditors, the appointment of a receiver, a
trustee, custodian or liquidator with respect to Borrower or any substantial
portion of Borrower's property, reorganization, arrangement, rearrangement,
composition, extension, liquidation or dissolution or similar relief under the
United States Bankruptcy Code or any state law. All reports, statements and
other data or applications for credit supplied to Lender by or on behalf of
Borrower or any guarantor prior to, contemporaneously with or subsequent to the
execution of this Agreement are true and correct in all material respects and do
not omit to state any fact or circumstance necessary to make the statements
contained therein not misleading. Any and all financial statements and
applications for credit have been prepared in accordance with generally accepted
accounting practices consistently applied, and fully and accurately present the
financial condition of the subject thereof as of the date thereof and no
material adverse change has occurred in the financial condition reflected
therein since the respective dates thereof.

      3.07. No Existing Violation or Default. Borrower is not in violation of or
in default with respect to any existing Legal Requirement, the payment of any
indebtedness or the terms or provisions of any agreement or instrument
evidencing or securing any such indebtedness.

      3.08. No Verbal Agreements. Borrower has not made any verbal or written
contract or arrangement of any kind, the occurrence, performance or recordation
of which would give rise to a lien or security interest in the Collateral.

      3.09. Taxes. Borrower has filed all federal, state and local tax reports
and returns required by any law or regulation to be filed by it, including,
without limitation, any and all payroll taxes, and has either duly paid all
taxes, duties and charges indicated due on the basis of such returns and
reports, or made adequate provision for the payment thereof, and the assessment
of any material amount of additional taxes in excess of those paid and reported
is not reasonably expected.

      3.10. Compliance with Applicable Laws. The location, construction,
occupancy, operation and use of the Collateral and the intended use thereof by
Borrower comply with all applicable restrictive covenants, zoning ordinances and
building codes, flood disaster laws, applicable health and environmental laws
and regulations and all other applicable laws, statutes, ordinances, rules,
regulations, orders, determinations and court decisions (all of the foregoing
hereinafter sometimes collectively referred to as "Applicable Laws"). Borrower
has obtained all requisite zoning, utility, building, health and operating
permits from the applicable Governmental Authority.

      3.11. Encumbrances. Borrower has good and marketable title to the
Collateral. The Collateral is free and clear from all liens, security interests
and encumbrances except the liens, security interests and encumbrances, if any,
set forth on Exhibit "B" attached hereto and made a part hereof.

      4.00. AFFIRMATIVE COVENANTS AND AGREEMENTS OF BORROWER. Until the Note and
all other obligations and liabilities of Borrower under this Agreement and the
other Loan Documents are fully paid and satisfied, Borrower covenants and agrees
with Lender as follows:

      4.01. Access to Records. Borrower shall maintain its books and records in
accordance with generally accepted accounting principles, applied on a
consistent basis, and permit Lender to visit its properties and installations

LOAN AGREEMENT - Page 4

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to examine, audit and make and take away copies or reproductions of Borrower's
books and records, at all reasonable times. Further, Borrower shall furnish
Lender with such additional information and statements, lists of assets and
liabilities, tax returns, and other reports with respect to Borrower's financial
condition and business operations as Lender may request from time to time.

      4.02. Insurance. Borrower shall maintain and comply with all terms of the
Casualty Insurance Policies and the Life Insurance Policy until the Loan is paid
in full. Borrower shall furnish renewal policies or certificates thereof at
least thirty (30) days prior to the expiration date of any policy. Borrower
shall cause the premiums on the Casualty Insurance Policies and Life Insurance
Policy to be paid as and when due, and shall deliver to Lender receipts
evidencing payment thereof.

      4.03. Proceedings Affecting Loan. Lender may (but shall not be obligated
to) commence, appear in or defend any action or proceeding purporting to affect
the Loan, the Collateral or the respective rights and obligations of Lender and
Borrower pursuant to this Agreement. Lender may (but shall not be obligated to)
pay all necessary expenses, including reasonable attorneys' fees and expenses,
incurred in connection with such proceedings or actions, which Borrower agrees
to repay to Lender upon demand.

      4.04. Further Assurances. Borrower will execute, re-execute and/or
initial any such document or instrument as may be requested by Lender in order
to (a) correct any errors or omissions in the Loan Documents, whether such error
or omission is due to the unilateral mistake of Lender, mutual mistake on the
part of Lender and Borrower or any guarantor, clerical mistake, calculation
error, computer malfunction, printing error or similar error, (b) carry out the
intent of the Loan Documents, or (c) perfect or give further assurances of any
of the rights, titles, liens or security interests granted or provided for in
any of the Loan Documents. Borrower further agrees that Lender shall not be
liable to Borrower for any damages incurred by Borrower that are directly or
indirectly caused by any such mistake, error or omission.

      4.05. Payment of Taxes. Borrower shall pay and discharge when due all of
its indebtedness and obligations, including without limitation, all assessments,
taxes; governmental charges, levies and liens, of every kind and nature, imposed
upon Borrower or its properties, income, or profits, prior to the date on which
penalties would attach, and all lawful claims that, if unpaid, might become a
lien or charge upon any of Borrower's properties, income, or profits. Upon the
request of Lender, Borrower shall furnish Lender with receipts of tax statements
marked "Paid" to evidence the payment of all taxes levied on the Collateral on
or before ten (10) days prior to the date such taxes become delinquent; provided
that Borrower may in good faith, by appropriate proceedings, contest the
validity, applicability, or amount of any asserted tax or assessment, and
pending such contest Borrower shall not be deemed in default hereunder if
Borrower shall diligently prosecute such contest in a manner not prejudicial to
the rights, liens and security interests of Lender and Borrower takes such
actions as Lender deems necessary to adequately provide for the payment of the
asserted tax or assessment with interest, costs and penalties. Lender shall have
the right (but shall have no obligation) to take, at any time, in its name or in
the name of Borrower, such action as Lender may at any time determine to be
necessary or advisable to cure any default or to protect the rights of Borrower
or Lender thereunder. Lender shall incur no liability for any action so taken by
it or on its behalf if such action shall prove to be inadequate or invalid.
Borrower agrees that any expense (including, but not limited to, attorneys fees)
incurred by Lender in connection with any such action shall become part of the
indebtedness evidenced and secured by the Loan Documents.

      4.06. Reporting Requirements. Borrower shall provide Lender:

            (a) As soon as possible and in any event within two (2) days after
      the occurrence of each Event of Default, as defined herein, or each event
      which, with the giving of notice or lapse of time or both, would
      constitute an Event of Default, continuing on the date of such statement,
      the written statement of a representative of Borrower satisfactory to
      Lender setting forth the details of such Event of Default or event and the
      action which Borrower proposes to take with respect thereto;

            (b) As soon as available, and in any event within forty-five (45)
      days after the end of each month (provided that Borrower shall have
      seventy-five (75) days after the last month of Borrower's fiscal year),

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      financial statements of Borrower prepared in accordance with generally
      accepted accounting principles, consistently applied, and including, but
      not limited to, a balance sheet and income statement of Borrower as of the
      end of such quarter, all in form and substance and in reasonable detail
      satisfactory to Lender;

            (c) Contemporaneously with each financial statement of Borrower
      required hereby, a certificate of the president or chief financial officer
      of Borrower that said financial statements are accurate and that there
      exists no Event of Default nor any condition, act or event which with the
      giving of notice or the passage of time or both would constitute an Event
      of Default;

            (d) As soon as available, and in any event within thirty (30) days
      of release, a copy of Borrower's annual audit;

            (e) As soon as available, and in any event within thirty (30) days
      of filing, copies of filed tax returns for the applicable taxing period;

            (f) Within forty-five (45) days after the end of each month, a
      current aging analysis of Borrower's accounts receivable and accounts
      payable, in form and substance satisfactory to Lender;

            (g) Within forty-five (45) days after the end of each month, a copy
      of Borrower's Borrowing Base Report and Compliance Certificate provided to
      Bank of America;

            (h) Notice of (i) any and all material adverse changes in Borrower's
      financial condition, (ii) all claims made against Borrower which could
      materially affect the financial condition of Borrower, and (iii) any
      change in the management (e.g., president, chief Financial officer, etc.)
      of Borrower;

            (i) Upon demand of Lender, evidence of payment of all assessments,
      taxes, charges, levies, liens and claims on or against Borrower's
      properties, income or profits, and authorize the appropriate governmental
      official to deliver to Lender at any time a written statement of any
      assessments, taxes, charges, levies, liens and claims against Borrower's
      properties, income or profits; and

            (j) Such other information respecting the business, properties or
      condition or the operations, financial or otherwise, of Borrower and/or
      any guarantor as Lender may from time to time request.

      4.07. Compliance with Loan Documents. Borrower shall use the proceeds of
the Loan for (a) working capital, and (b) to refinance Borrower's existing debts
to Lender. Borrower shall perform and comply with all terms, conditions, and
provisions set forth in this Loan Agreement and in all other instruments and
agreements between Borrower and Lender, including without limitation, the other
Loan Documents.

      4.08. Conduct of Business. Borrower shall conduct its business in an
orderly and efficient manner consistent with good business practices, and
perform and comply with all Legal Requirements.

      5.00. NEGATIVE COVENANTS. Until the Note and all other obligations and
liabilities of Borrower under this Agreement and the other Loan Documents are
fully paid and satisfied, Borrower will not, without the prior written consent
of Lender:

            (a) make any material change in the nature of its business as
      carried on as of the date hereof;

            (b) liquidate, merge or consolidate with or into any other entity;

            (c) sell, transfer or otherwise dispose of any of its assets or
      properties, other than in the ordinary course of business;

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            (d) create, incur or assume any lien or encumbrance on any of its
      assets or properties, including without limitation, the Collateral, except
      as may be expressly permitted hereunder;

            (e) create, incur or assume any indebtedness for borrowed money or
      issue or assume any other note, debenture, bond or other evidences of
      indebtedness, or guarantee any such indebtedness or such evidences of
      indebtedness of others, other than (i) indebtedness to Lender, (ii)
      existing indebtedness as of the date hereof and disclosed in writing to
      Lender, (iii) trade debt incurred in the ordinary course of business, or
      (iv) purchase money financing; or

            (f) relocate its offices or conduct its primary business operations
      from a location other than at the address set forth for notices in section
      8.05 below.

            (g) advance, pay, remit or distribute funds to any Affiliate (as
      hereinafter defined) of Borrower, except in the ordinary course of and
      pursuant to the reasonable requirements of Borrower's business and upon
      fair and reasonable terms no less favorable to Borrower than would be
      obtained in a comparable arm's-length transaction with a person or entity
      not an Affiliate of Borrower. As used herein, the term "Affiliate" means
      any individual or entity directly or indirectly controlling, controlled
      by, or under common control with, another individual or entity.

      6.00. INDEMNITY. Borrower hereby agrees to indemnify, defend at its sole
cost and expense and hold Lender and its successors and assigns harmless from
and against and to reimburse Lender with respect to, any and all claims,
demands, actions, causes of action, losses, damages, liabilities, costs and
expenses (including without limitation attorney's fees and court costs) of any
and every kind of character, known or unknown, fixed or contingent, asserted
against or incurred by Lender at any time and from time to time by reason of or
arising out of (a) the breach of any representation or warranty of Borrower set
forth herein, (b) the failure of Borrower, in whole or in part, to perform any
obligation required in any Loan Document to be performed by Borrower; and (c)
the ownership, construction, occupancy, operation, use and maintenance of the
Collateral. This indemnity applies, without limitation, to any violation of any
applicable environmental law and any and all matters arising out of any act,
omission, event or circumstance presently existing or hereafter arising
(including without limitation the presence on the Collateral or release from the
Collateral of hazardous substances or solid waste disposed of or otherwise
released), regardless of whether the act, omission, event or circumstance
constituted a violation of any applicable environmental law at the time of its
existence or occurrence.

      7.00. EVENTS OF DEFAULT AND REMEDIES.

      7.01. Events of Default. The occurrence of any one or more of the
following shall constitute an Event of Default hereunder:

            (a) The failure of Borrower to pay the principal of or interest on
      the Note as and when the same becomes due and payable in accordance with
      the terms of the Note, and such failure shall continue for a period of ten
      (10) days after receipt of written notice from Lender specifying such
      failure, provided, however, that Lender shall be obligated to give only
      one (1) such notice in a calendar year and, after the giving of such one
      notice, Lender shall be entitled to exercise its remedies upon any
      subsequent default occurring within such calendar year without any
      requirement of notice;

            (b) The failure of Borrower or any other party to perform any of the
      covenants, obligations or agreements contained in this Agreement, the
      Note, the Security Instrument or any of the other Loan Documents, other
      than as set forth in Subsection 7.01 (a) above, and such failure shall
      continue for a period of thirty (30) days after receipt of written notice
      from Lender specifying such failure;

            (c) The occurrence of a default or event of default under any of the
      Loan Documents other than as set forth in Subsections 7.01 (a) and (b)
      above;

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            (d) Any default in the payment or performance of any obligation, or
      any defined event of default, under the terms of any contract or
      instrument (other than any of the Loan Documents) pursuant to which
      Borrower or any general partner in Borrower has incurred any debt or other
      liability to any person or entity, including Lender.

            (e) Any representation contained herein or in any other Loan
      Document by Borrower or any guarantor is false or misleading in any
      material respect;

            (f) Any report, certificate, financial statement or other instrument
      furnished by or on behalf of Borrower or any guarantor any time is
      knowingly false and misleading in any material respect;

            (g) Any substantial damage to or destruction of the Collateral shall
      occur so that, in the opinion of Lender, it cannot be restored or rebuilt
      with available funds to a profitable condition within a reasonable period
      of time;

            (h) If Borrower or any guarantor is an entity, the liquidation,
      dissolution, merger, consolidation, forfeiture of the corporate charter or
      revocation or withdrawal of the certificate of authority of any such
      entity;

            (i) If Borrower or any guarantor (i) becomes insolvent, or makes a
      transfer in fraud of creditors, or makes an assignment for the benefit of
      creditors, or admits in writing its inability to pay its debts as they
      become due; (ii) generally is not paying its debts as such debts become
      due; (iii) has a receiver or custodian appointed for, or take possession
      of, all or substantially all of the assets of such party, either in a
      proceeding brought by such party or in a proceeding brought against such
      party and such appointment is not discharged or such possession is not
      terminated within thirty (30) days after the effective date thereof or
      such party consents to or acquiesces in such appointment or possession;
      (iv) files a petition for relief under the United States Bankruptcy Code
      or any other present or future federal or state insolvency, bankruptcy or
      similar laws (all of the foregoing hereinafter collectively called
      "Applicable Bankruptcy Law") or an involuntary petition for relief is
      filed against such party under any Applicable Bankruptcy Law and such
      involuntary petition is not dismissed within thirty (30) days after the
      filing thereof, or an order for relief naming such party is entered under
      any Applicable Bankruptcy Law, or any composition, rearrangement,
      extension, reorganization or other relief of debtors now or hereafter
      existing is requested or consented to by such party; (v) fails to have
      discharged within a period of thirty (30) days any attachment,
      sequestration or similar writ levied upon any property of such party; or
      (vi) fails to pay within thirty (30) days any final money judgment against
      such party;

            (j) The holder of any lien or security interest on the Collateral
      (without hereby implying the consent of Lender to the existence or
      creation of a such lien or security interest) declares a default
      thereunder or institutes foreclosure or other proceedings for the
      enforcement of its remedies thereunder;

            (k) If any lien granted under the Loan Documents becomes invalid,
      unenforceable, or is not, or ceases to be, a perfected lien in favor of
      Lender against any asset which it is intended to encumber;

            (l) If Borrower shall cease to conduct business or materially
      changes the nature of its business operations and activities as existing
      on the date hereof;

            (m) If there shall occur a material adverse change in the assets,
      liability, financial condition or business operation of Borrower or any
      guarantor.

Nothing contained in this Agreement shall be construed to limit the events of
default enumerated in any of the other Loan Documents and all such events of
default shall be cumulative.

      7.02. General Remedies of Lender. Upon the occurrence of any Event of
Default, Lender shall have the right, at its option, without notice or demand
upon Borrower or any other party (except as expressly provided for herein or by
applicable law) to do the following: (a) declare the unpaid balance of the Loan
(including all principal thereof and

LOAN AGREEMENT - Page 8

<PAGE>

all interest then accrued thereon) to be immediately due and payable; (b) cease
further advances under the Loan; (c) enter and take possession of the Collateral
to the exclusion of Borrower; and/or (d) enforce or avail itself of any and all
remedies provided in any of the Loan Documents, at law or equity.

      7.03. Waiver by Borrower. Borrower and all other parties liable for the
indebtedness and obligations set forth in the Note and the Loan Documents,
hereby expressly waive demand, notice of intent to demand, presentment for
payment, notice of nonpayment, protest, notice of protest, grace, notice of
dishonor, notice of intent to accelerate maturity, notice of acceleration of
maturity, and diligence in collection.

      7.04. Remedies Cumulative. All powers, rights and remedies of Lender set
forth in this Agreement shall be cumulative and not exclusive of any other
power, right or remedy available to Lender under this Agreement, the other Loan
Documents or at law or in equity to enforce the performance or observance of the
covenants and agreements contained in this Agreement and the other Loan
Documents, and no delay or omission of Lender to exercise any power, right or
remedy accruing to Lender shall impair any such power, right or remedy, or shall
be construed to be a waiver of the right to exercise any such power, right or
remedy. Every power, right and remedy of Lender set forth in this Agreement, the
other Loan Documents or afforded by law may be exercised from time to time, and
as often as may be deemed expedient, by Lender.

      8.00. MISCELLANEOUS PROVISIONS.

      8.01. Form and Execution of Documents. Each written instrument and Loan
Document required by this Agreement or any of the other Loan Documents to be
furnished to Lender shall be furnished to Lender in one or more copies as
required by Lender and shall in all respects be in form and substance
satisfactory to Lender and to its legal counsel.

      8.02. Controlling Agreement. All agreements between Borrower and Lender,
whether now existing or hereafter arising and whether written or oral, are
hereby limited so that in no contingency or event whatsoever, whether by reason
of demand or acceleration of the maturity or otherwise, shall the interest
contracted for, charged, received, paid or agreed to be paid to Lender exceed
interest computed at the Maximum Rate (as defined below). If, from any
circumstance whatsoever, interest would otherwise be payable to Lender in excess
of interest computed at the Maximum Rate, the interest payable to Lender shall
be reduced to interest computed at the Maximum Rate; and if from any
circumstance Lender shall ever receive anything of value deemed interest by
applicable law in excess of interest computed at the Maximum Rate, an amount
equal to any excessive interest shall be applied to the reduction of the
principal balance of the Loan and not to the payment of interest, or if such
excessive interest exceeds the unpaid balance of principal of the Loan, such
excess shall be refunded to the Borrower. All interest paid or agreed to be paid
to Lender shall, to the extent permitted by applicable law, be amortized,
prorated, allocated, and spread throughout the full period until payment in full
of the principal (including the period of any renewal or extension) so that the
interest for such full period shall not exceed interest computed at the Maximum
Rate. This section shall control all agreements between Borrower and Lender. The
term "Maximum Rate" shall mean the highest lawful rate of interest applicable to
the loan transaction evidenced by the Note taking into account whichever of
applicable federal law or Texas law permits the higher rate of interest, and
after also taking into consideration all compensation deemed interest under
applicable law.

      8.03. Severability. In the event any provision of this Agreement is
declared or adjudged to be unenforceable or unlawful, then such unenforceable or
unlawful provision shall be excised herefrom, and the remainder of this
Agreement not so affected, together with all rights and remedies granted hereby,
shall continue and remain in full force and effect as though such unlawful or
unenforceable provision had never been contained therein.

      8.04. No Waiver. No course of dealing between Lender and Borrower, nor any
delay on the part of Lender in exercising any rights hereunder or under any of
the other Loan Documents, nor any failure of Lender at any time to enforce any
provision of this Agreement or any of the other Loan Documents, shall operate as
a waiver of any rights of Lender, except to the extent, if any, expressly waived
in writing by Lender. Lender shall have the right at any and all times, without
any prior notice to any person, to enforce strict compliance with all of the
provisions hereof and the other Loan Documents, notwithstanding any such prior
course of dealing or forbearance.

LOAN AGREEMENT - Page 9

<PAGE>

      8.05. Notices. Any notice, request or other communication required or
permitted to be given hereunder shall be in writing and shall be deemed to have
been given and received when deposited in a post office or official depository
of the United States Postal Service, postage prepaid, certified or registered
mail, return receipt requested, addressed to the respective parties as follows:

      If to the Borrower:    Drew Scientific, Inc.
                             4230 Shilling Way
                             Dallas, Texas 75237
                             Attn: Keith Drew

      If to the Lender:      Texas Mezzanine Fund Inc.
                             351 West Jefferson Blvd., Suite 800
                             Dallas, Texas 75208
                             Attn: Theresa Lee

Each of the parties hereto shall be entitled to specify a different address by
giving written notice to the other party hereto in accordance with this section.

      8.06. Counterparts. This Agreement may be executed simultaneously in any
number of counterparts, each of which when so executed and delivered shall be an
original, but such counterparts shall together constitute one and the same
instrument.

      8.07. Payment of Fees and Expenses. Borrower shall pay when due, and
reimburse to Lender on demand, and indemnify Lender from, all out-of-pocket
fees, costs, and expenses paid or incurred by Lender in connection with the
negotiation, preparation and execution of this Agreement and the other Loan
Documents (and any amendments, approvals, consents, waivers and releases
requested, required, proposed or done from time to time), or in connection with
the disbursement, administration or collection of the Loan or the enforcement of
the obligations or the exercise of any right or remedy of Lender, including, but
not limited to (a) fees and expenses of Lender's counsel; (b) survey costs; (c)
title insurance charges; (d) title search or examination costs, including
abstracts, abstractors' certificates and uniform commercial code searches; (e)
escrow fees; and (f) filing and recording fees. Borrower's obligations under
this Section shall survive the delivery of the Loan Documents, the making of
advances, the payment in full of the obligations, the release or determination
of the Loan Documents, the foreclosure of the Security Instrument or conveyance
in lieu of foreclosure, any bankruptcy or other debtor relief proceeding, and
any other event whatsoever.

      8.08. Principles of Construction. In this Agreement, the singular number
shall include the plural and vice versa. All pronouns shall include masculine,
feminine and neuter gender, as appropriate, regardless of gender used. Titles of
articles and sections are for convenience only and shall not limit the
applicability of any provision.

      8.09. GOVERNING LAW AND VENUE. THIS AGREEMENT, THE OTHER LOAN DOCUMENTS
AND THE RIGHTS AND OBLIGATIONS OF THE PARTIES HEREUNDER AND THEREUNDER SHALL BE
GOVERNED BY AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH THE LAWS OF THE
STATE OF TEXAS AND APPLICABLE FEDERAL LAW. UNLESS OTHERWISE HEREIN PROVIDED, ALL
PAYMENTS AND PERFORMANCES REQUIRED HEREUNDER SHALL BE PAID OR PERFORMED IN
DALLAS COUNTY, TEXAS. VENUE OF ANY SUIT ARISING HEREUNDER SHALL LIE IN DALLAS
COUNTY, TEXAS .

      8.10. FINAL AGREEMENT. THIS WRITTEN AGREEMENT AND THE OTHER LOAN DOCUMENTS
REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES WITH RESPECT TO THE MATTERS
CONTAINED HEREIN AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

LOAN AGREEMENT - Page 10

<PAGE>

EXECUTED this 20th day of November, 2003.

                                 LENDER:

                                 TEXAS MEZZANINE FUND INC.,
                                 a Texas corporation

                                 By: /s/ Theresa Lee
                                     ------------------------
                                 Name: Theresa Lee
                                 Title: Vice-President

                                 BORROWER:

                                 DREW SCIENTIFIC, INC.,
                                 a Texas corporation

                                 By: /s/ Keith Drew
                                     ------------------------
                                 Name: Keith Drew
                                 Title: President

LOAN AGREEMENT - Page 11

<PAGE>

                                    Exhibit B
                Permitted Liens/Security Interests/Encumbrances

1.    Financing Statement No. 99-156605 filed on August 3, 1999 in the Office of
      the Secretary of State of the State of Texas, MWI, Inc. dba Danam
      Electronics, as debtor, Texas Mezzanine Fund, Inc., as secured party,
      covering all accounts, inventory and equipment, with security interest in
      (a) export related accounts and inventory subordinated to the security
      interest of Bank of America, N.A., and (b) domestic accounts and inventory
      subordinated to the security interest of Vertex Financial Corporation
      pursuant to Intercreditor Agreement by and among Texas Mezzanine Fund,
      Inc., Bank of America, N.A. and Vertex financial Corporation dated March
      7, 2002, as amended.

2.    Financing Statement No. 00-520328 filed on June 12, 2000 in the Office of
      the Secretary of State of the State of Texas, MWI, Inc. dba Danam
      Electronics, as debtor, Bank of America, N.A., as secured party, covering
      all accounts, inventory and equipment, as amended by Financing Statements
      02-00199789, 02-00210790, 02- 00277004 and 02-00302353.

3.    Financing Statement No. 0002038371 filed on December 5,2000 in the Office
      of the Secretary of State of the State of Connecticut, MWI, Inc. , as
      debtor, Associates Leasing, Inc., as secured party, covering one (1)
      Daewoo Mynx 500.

4.    Financing Statement No. 02-0024567117 filed on April 1, 2002 in the Office
      of the Secretary of State of the State of Texas, MWI, Inc., as debtor,
      Vertex Financial Corporation, as secured party, covering all domestic
      accounts and inventory, as amended by Financing Statement No. 03-00121476.<PAGE>
                                                                   Exhibit 10.52

                               GUARANTY AGREEMENT

      This GUARANTY AGREEMENT (this "Guaranty") is entered into by DREW
SCIENTIFIC GROUP, PLC, a public limited company organized under the laws of
England and Wales ("Guarantor") in favor of TEXAS MEZZANINE FUND INC., a Texas
corporation ("Lender").

                             W  I  T  N  E  S  S  E  T  H :

      WHEREAS, Drew Scientific, Inc., a Texas corporation ("Borrower"), desires
to borrow from Lender an aggregate principal sum of Five Hundred Fifty-Eight
Thousand and No/100 Dollars ($558,000.00) (the "Loan");

      WHEREAS, the Loan is evidenced by a promissory note in the stated
principal amount of Five Hundred Fifty-Eight Thousand and No/100 Dollars
($558,000.00) (the "Note") executed by Borrower in favor of Lender;

      WHEREAS, said Note is to be executed and delivered pursuant to the terms
of a Loan Agreement dated of even date herewith between Borrower and Lender (the
"Loan Agreement") (The Note, the Loan Agreement and any of the other documents
executed in connection with the Loan are hereinafter collectively referred to as
the "Loan Documents"); and

      WHEREAS, the Lender requires, as a condition precedent to funding the
Loan, a guaranty in the form hereof be executed by the undersigned.

      NOW, THEREFORE, in consideration of the premises and to induce the Lender
to enter into the Loan, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the undersigned hereby
agrees as follows:

      1. Guaranteed Indebtedness. Guarantor hereby guarantees to Lender and to
every subsequent holder or holders of the Note that (a) the principal of and
interest on, and attorneys' fees provided in the Note will be promptly paid when
due in accordance with the provisions thereof, or, in the case of extension of
time of payment, in whole or in part of the Note, all sums will be promptly paid
when due in accordance with the terms of the extensions, (b) all covenants and
agreements of the Borrower contained in the Loan Documents will be duly and
promptly observed and performed, and (c) all additional amounts owing or which
hereafter become owing by the Borrower under the terms of the Loan Documents
will be promptly paid when due.

      2. Guaranty of Payment and Performance; Waiver of Defenses. The
obligations of the Guarantor shall be performable without demand of Lender. The
obligations of the Guarantor hereunder shall not be affected by or dependent
upon the genuineness, validity, regularity or enforceability of the Loan
Documents or any other circumstance which might otherwise constitute a legal or
equitable discharge of a surety or a guarantor. The Guarantor hereby (except as
otherwise provided herein) waives diligence, presentment, demand or payment,
protest, all notices (whether of nonpayment, dishonor, protest or otherwise)
with respect to the Note, notice of acceptance of this Guaranty and of the
incurring by the Borrower of any of the obligations hereinbefore mentioned, and
all rights to require the Lender to (a) proceed against the Borrower, (b)
proceed against or exhaust any collateral held by the Lender to secure the
payment of the indebtedness guaranteed hereby, or (c) pursue any other remedy it
may now or hereafter have against the Borrower or any other endorser, guarantor
or surety. Guarantor waives all defenses given to sureties or guarantors at law
or in equity other than the actual payment of the indebtedness guaranteed hereby
and Guarantor waives all defenses based upon questions as to the validity,
legality or enforceability of the Loan and/or the obligations in connection with
the Loan and agrees that Guarantor shall be primarily liable hereunder.

      3. Extensions or Modifications of Obligations. The Guarantor hereby agrees
that, at any time or from time to time, without notice or the consent of the
Guarantor, Lender may do any of the following acts without affecting the
liability of the Guarantor:

GUARANTY AGREEMENT - Page 1

<PAGE>

      (a) Extend the time for payment of the principal of or interest on the
Note, or any part thereof, or renew the Note in whole or in part, or accept
another note containing other or different provisions in substitution therefor;

      (b) Extend the time for, waive, renew, rearrange, modify or amend (whether
material or otherwise), any of Borrower's covenants, agreements, duties or
obligations contained in any of the Loan Documents;

      (c) Accelerate the maturity of the Note as provided therein or in the Loan
Agreement or any and all other Loan Documents;

      (d) Modify, exchange, surrender, abandon or release any security for the
Note;

      (e) Foreclose on any security for the Note in any manner authorized by law
or the Loan Documents;

      (f) Waive any condition precedent to the making of any advance to Borrower
required by the terms of any of the Loan Documents or make such advance
notwithstanding the existence at the time of such advance of an Event of Default
or potential default under any of the Loan Documents; or

      (g) Do any other act, or make any other agreement with the Borrower or any
other party interested in property given as security for the Loan, or with any
endorser, guarantor or surety who may be liable to pay the indebtedness
guaranteed hereby in whole or in part, as Lender may deem necessary and
appropriate.

In the event of any extension or modification of any of the indebtedness or
obligations of Borrower, this Guaranty shall also cover, and Guarantor hereby
guarantees the timely payment and performance of the indebtedness and
obligations of Borrower as so extended or modified.

      4. Subordination. Any indebtedness of the Borrower now or hereafter held
by the Guarantor is hereby subordinated to all indebtedness of the Borrower to
the Lender guaranteed hereby and such indebtedness of the Borrower shall be
collected, enforced, and received by the Guarantor as trustee for the Lender,
but without reducing or affecting in any manner the liability of the Guarantor
under the other provisions of this Guaranty. So long as any amount of the Loan
remains outstanding and unpaid, Guarantor shall not be subrogated to any rights
of Lender provided in the Loan Documents against Borrower or any property
securing the Loan.

      5. Costs and Attorneys' Fees. If this Guaranty shall be placed in the
hands of an attorney for collection or should it be collected by legal
proceedings or through any probate or bankruptcy court, the Guarantor agrees to
pay to the Lender all costs, reasonable attorneys' and collection fees incurred
in connection therewith.

      6. Assignability and Successors. The Lender may assign its rights
hereunder in whole or in part, and upon any such assignment all the terms and
provisions of this Guaranty shall inure to the benefit of such assignee, to the
extent so assigned. The terms used to designate any of the parties herein shall
be deemed to include the heirs, legal representatives, successors and assigns of
such parties; and the term "Lender" shall include, in addition to Texas
Mezzanine Fund Inc., any lawful owner, holder or pledgee of any indebtedness
guaranteed hereby.

      7. Severability. The Lender is relying and is entitled to rely upon each
and all of the provisions of this Guaranty; and accordingly, if any provision or
provisions of this instrument should be held to be invalid or ineffective, then
all other provisions shall continue in full force and effect to the same extent
and in the same manner as though such invalid or unenforceable provision had
never been contained herein.

      8. Representations and Warranties. The Guarantor represents and warrants
to the Lender that (a) this Guaranty is a legal, valid and binding obligation of
Guarantor, enforceable against Guarantor in accordance with its terms; (b) the
execution, delivery, and performance by Guarantor of this Guaranty does not and
will not violate any authority having the force of law or any indenture,
agreement, or other instrument to which Guarantor is a party or by which
Guarantor or any of the properties or assets of Guarantor are or may be bound;
(c) there are no actions, suits or proceedings pending, or to the knowledge of
Guarantor, threatened against or affecting Guarantor or Borrower; (d)

GUARANTY AGREEMENT - Page 2

<PAGE>

Guarantor shall not, without the prior written consent of Lender, sell, lease,
assign, encumber, transfer or otherwise dispose of all or a substantial or
material part of Guarantor's assets other than in the ordinary course of
Guarantor's business; (e) all balance sheets, earning statements and other
financial data which have been furnished by Guarantor to Lender to induce it to
enter into this Guaranty or the Loan (i) are true and correct in all material
respects, having been prepared in accordance with generally accepted accounting
practices applied on a consistent basis throughout the period covered thereby,
(ii) fairly represent the financial condition of Guarantor and the results of
Guarantor's operations for the periods for which the same are furnished, and
(iii) since the date thereof, there has been no material adverse change in the
financial condition of Guarantor; (f) all other information, reports and other
papers and data furnished to Lender by or on behalf of Guarantor are or shall be
at the time the same are so furnished, accurate and correct in all material
respects and complete insofar as necessary to give Lender a true and accurate
knowledge of the subject matter; and (g) Guarantor is solvent.

      9. Further Assurances. Guarantor agrees to execute, re-execute and/or
initial any such document or instrument as may be requested by Lender in order
to (a) correct any errors or omissions in this Guaranty or any other Loan
Document, whether such error or omission is due to the unilateral mistake of
Lender, mutual mistake on the part of Lender and Borrower or Guarantor or any
other guarantor, clerical mistake, calculation error, computer malfunction,
printing error or similar error, or (b) give further assurances of any of the
rights granted or provided for in this Guaranty. Guarantor further agrees that
Lender shall not be liable to Guarantor for any damages incurred by Guarantor
that are directly or indirectly caused by any such mistake, error or omission.

      10. Financial Reports. Guarantor shall provide its annual audit to Lender
within thirty (30) days of release. Guarantor shall also provide Lender with
such other information respecting the business, properties or condition or the
operations, financial or otherwise, of Guarantor, as Lender may from time to
time reasonably request.

      11. Rights Against Borrower or Collateral. The Guarantor agrees that
Lender, in its discretion, may (a) bring suit against the Guarantor and any
other endorser, guarantor, or surety of the Note jointly and severally or
against any one or more of them, in either case with or without joinder of the
Borrower, (b) compound or settle with the Borrower, the Guarantor or any other
endorser, guarantor or surety for such consideration as the Lender may deem
proper, (c) release the Borrower, the Guarantor or any other endorser,
guarantor, or surety of the Note from liability thereunder, or (d) release or
abandon any property securing the indebtedness hereby guaranteed or any part
thereof or dispose of any such property in any manner and for any consideration
deemed appropriate by Lender, and that no such action shall impair the rights of
the Lender to collect the indebtedness hereby guaranteed from the Guarantor.
Nothing contained in this paragraph, and no action by Lender permitted under
this paragraph, shall in any way affect or impair the rights or obligations of
the Guarantor with respect to any other guarantor, endorser or surety of the
Note.

      12. Benefit to Guarantor. The Guarantor acknowledges and warrants that he
has derived or expects to derive financial and other advantage and benefit,
directly or indirectly, from the Loan and each and every advance thereof and
from each and every renewal, extension, amendment, increase, replacement,
release of collateral or other relinquishment of legal rights made or granted or
to be made or granted by Lender to Borrower.

      13. Lawful Interest. All agreements between Guarantor and Lender, whether
now existing or hereafter arising and whether written or oral, are hereby
limited so that in no contingency or event whatsoever, whether by reason of
demand or acceleration of the maturity or otherwise, shall the interest
contracted for, charged, received, paid or agreed to be paid to Lender exceed
interest computed at the Maximum Rate (as defined below). If, from any
circumstance whatsoever, interest would otherwise be payable to Lender in excess
of interest computed at the Maximum Rate, the interest payable to Lender shall
be reduced to interest computed at the Maximum Rate; and if from any
circumstance Lender shall ever receive anything of value deemed interest by
applicable law in excess of interest computed at the Maximum Rate, an amount
equal to any excessive interest shall be applied to the reduction of the
principal balance of the Loan and not to the payment of interest, or if such
excessive interest exceeds the unpaid balance of principal of the Loan, such
excess shall be refunded. All interest paid or agreed to be paid to Lender
shall, to the extent permitted by applicable law, be amortized, prorated,
allocated, and spread throughout the full period until payment in full of the
principal (including the period of any renewal or extension) so that the
interest for such full period shall not exceed interest computed at the Maximum
Rate. This section shall control all agreements between Guarantor and Lender.
The

GUARANTY AGREEMENT - Page 3

<PAGE>

term "Maximum Rate" shall mean the highest lawful rate of interest applicable to
the loan transaction evidenced by the Note taking into account whichever of
applicable federal law or Texas law permits the higher rate of interest, and
after also taking into consideration all compensation deemed interest under
applicable law.

      14. GOVERNING LAW AND VENUE. THIS GUARANTY AND ALL RIGHTS,OBLIGATIONS AND
LIABILITIES ARISING HEREUNDER SHALL BE CONSTRUED ACCORDING TO THE LAWS OF THE
STATE OF TEXAS. ALL OBLIGATIONS ARISING UNDER THIS GUARANTY SHALL BE PERFORMABLE
IN DALLAS COUNTY, TEXAS. VENUE OF ANY SUIT ARISING HEREUNDER SHALL LIE IN DALLAS
COUNTY, TEXAS.

      15. Notice. Any notice required or permitted hereunder shall be in
writing, and shall be deemed to have been given and received when deposited in a
post office or official depository of the United States Postal Service, sent by
certified mail, postage prepaid, return receipt requested, addressed as follows:

      Guarantor:                 Drew Scientific Group, PLC
                                 Park Road Barrow in Furness
                                 Cumbria LA14 4QR
                                 United Kingdom
                                 Attn: DAVID BLAIN

      Lender:                    Texas Mezzanine Fund Inc.
                                 351 West Jefferson Blvd., Suite 800
                                 Dallas, Texas 75208
                                 Attn: Theresa Lee

The addresses set forth in this Guaranty may be changed by any party by giving
notice of such change to the other party in the manner provided herein for
giving notice.

      16. Number and Gender. In construing this Guaranty, the singular number
shall include the plural and vice versa, and all pronouns shall include male,
female and neuter gender, regardless of gender used.

      17. FINAL AGREEMENT. THIS WRITTEN GUARANTY AND THE OTHER LOAN DOCUMENTS
REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY
EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.
THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

      IN WITNESS WHEREOF, this Guaranty has been duly executed by the
undersigned this 20th day of November, 2003.

                                                DREW SCIENTIFIC GROUP, PLC,
                                                a public limited company
                                                organized under the laws of
                                                England and Wales

                                                By: /s/ K.R. Drew
                                                    -------------------
                                                Name: K.R. DREW
                                                Title: DIRECTOR

GUARANTY AGREEMENT - Page 4

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