FORM OF DAWSON JAMES WARRANT]

EXHIBIT 4.18

▇▇▇▇▇▇▇▇▇▇ LABORATORIES, INC.

▇▇▇▇▇▇▇▇▇▇ Laboratories, Inc., a Texas corporation (the "Company"), hereby certifies that, for value received, [Name of Holder] or its registered assigns (the "Holder"), is entitled to purchase from the Company up to a total of [ ] shares of common stock, $0.01 par value per share (the "Common Stock"), of the Company (each such share, a "Warrant Share" and all such shares, the "Warrant Shares") at an exercise price equal to $2.01 per share (as adjusted from time to time as provided in Section 9, the "Exercise Price"), at any time and from time to time from and after October 26, 2007 and through and including the date that is five years after the Effective Date of the initial Registration Statement filed pursuant to the Securities Purchase Agreement (the "Expiration Date"), and subject to the following terms and conditions. This Warrant (this "Warrant") is one of a series of similar Warrants issued in connection with that certain Securities Purchase Agreement, dated as of April 25, 2007, by and among the Company and the Purchasers identified therein (the "Purchase Agreement"). All such Warrants are referred to herein, collectively, as the "Warrants."

1.      Definitions. In addition to the terms defined elsewhere in this Warrant, capitalized terms that are not otherwise defined herein have the meanings given to such terms in the Purchase Agreement.

2.      Registration of Warrant. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the "Warrant Register"), in the name of the record Holder hereof from time to time. The Company may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder, and for all other purposes, absent actual notice to the contrary.

3.      Registration of Transfers. The Company shall register the transfer of any portion of this Warrant in the Warrant Register, upon surrender of this Warrant, with the Form of Assignment attached hereto duly completed and signed, to the Transfer Agent or to the Company at its address specified herein. Upon any such registration or transfer, a new warrant to purchase Common Stock, in substantially the form of this Warrant (any such new warrant, a "New Warrant"), evidencing the portion of this Warrant so transferred shall be issued to the transferee and a New Warrant evidencing the remaining portion of this Warrant not so transferred, if any, shall be issued to the transferring Holder. The acceptance of the New Warrant by the transferee thereof shall be deemed the acceptance by such transferee of all of the rights and obligations of a holder of a Warrant.

4.      Exercise and Duration of Warrants.

(a)      This Warrant shall be exercisable by the registered Holder at any time and from time to time on or after October 26, 2007 through and including the Expiration Date. At 6:30 P.M., New York City time on the Expiration Date, the portion of this Warrant not exercised prior thereto shall be and become void and of no value; provided that, if the average of the Closing Prices for the five Trading Days immediately prior to (but not including) the Expiration Date exceeds the Exercise Price on the Expiration Date, then this Warrant shall be deemed to have been exercised in full (to the extent not previously exercised) on a "cashless exercise" basis at 6:30 P.M. New York City time on the Expiration Date if a "cashless exercise" may occur at such time pursuant to Section 10 below.

(b)      A Holder may exercise this Warrant by delivering to the Company (i) an exercise notice, in the form attached hereto (the "Exercise Notice"), appropriately completed and duly signed, and (ii) payment of the Exercise Price for the number of Warrant Shares as to which this Warrant is being exercised (which may take the form of a "cashless exercise" if so indicated in the Exercise Notice and if a "cashless exercise" may occur at such time pursuant to this Section 10 below), and the date such items are delivered to the Company (as determined in accordance with the notice provisions hereof) is an "Exercise Date." The Holder shall not be required to deliver the original Warrant in order to affect an exercise hereunder. Execution and delivery of the Exercise Notice shall have the same effect as cancellation of the original Warrant and issuance of a New Warrant evidencing the right to purchase the remaining number of Warrant Shares.

(c)      Upon delivery of the Exercise Notice, with payment in respect thereof, the Holder shall be deemed for all corporate purposes to have become the holder of record of the Warrant Shares with respect to which this Warrant has been exercised, irrespective of the date such Warrant Shares are credited to the Holder's account or the date of delivery of the certificates evidencing such Warrant Shares, as the case may be.

5.      Delivery of Warrant Shares.

(a)      Upon exercise of this Warrant, the Company shall promptly (but in no event later than three Trading Days after the Exercise Date) issue or cause to be issued and cause to be delivered to or upon the written order of the Holder and in such name or names as the Holder may designate, the Warrant Shares issuable upon such exercise, free of restrictive legends unless a registration statement covering the resale of the Warrant Shares and naming the Holder as a selling shareholder thereunder is not then effective and the Warrant Shares are not freely transferable without volume restrictions pursuant to Rule 144 under the Securities Act. The Holder, or any Person so designated by the Holder to receive Warrant Shares, shall be deemed to have become holder of record of such Warrant Shares as of the Exercise Date. The Company may, and upon request of the Holder shall use its reasonable best efforts to, deliver Warrant Shares hereunder electronically through the Depository Trust Corporation or another established clearing corporation performing similar functions.

(b)      This Warrant is exercisable, either in its entirety or, from time to time, for a portion of the number of Warrant Shares. Upon surrender of this Warrant following one or more partial exercises, the Company shall issue or cause to be issued, at its expense, a New Warrant evidencing the right to purchase the remaining number of Warrant Shares.

(c)      In addition to any other rights available to a Holder, if the Company fails to deliver to the Holder the Warrant Shares by the third Trading Day after the date on which delivery is required by this Warrant, (x) the Company shall pay in cash to the Holder on each day after such third Trading Day that the issuance of such Warrant Shares is not timely effected an amount equal to 1.0% of the product of (1) the sum of the number of Warrant Shares not issued to the Holder on a timely basis and to which the Holder is entitled and (2) the VWAP of the Warrant Shares on the Trading Day immediately preceding the last possible date which the Company could have issued such Warrant Shares to the Holder without violating this provision, or (y) if after such third Trading Day the Holder purchases (in an open market transaction or otherwise) shares of Common Stock to deliver in satisfaction of a sale by the Holder of the Warrant Shares that the Holder anticipated receiving from the Company (a "Buy-In"), then the Company shall, within three Trading Days after the Holder's request and in the Holder's discretion, either (i) pay cash to the Holder in an amount equal to the Holder's total purchase price (including brokerage commissions, if any) for the shares of Common Stock so purchased (the "Buy-In Price"), at which point the Company's obligation to deliver such certificate (and to issue such Common Stock) shall terminate, or (ii) promptly honor its obligation to deliver to the Holder a certificate or certificates representing such Common Stock or deliver such Common Stock to the Holder's account and pay cash to the Holder in an amount equal to the excess (if any) of the Buy-In Price over the product of (A) such number of shares of Common Stock, times (B) the Closing Price on the date of the event giving rise to the Company's obligation to deliver such Warrant Shares.

(d)      The Company's obligations to issue and deliver Warrant Shares in accordance with the terms hereof are absolute and unconditional, irrespective of any action or inaction by the Holder to enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against any Person or any action to enforce the same, or any setoff, counterclaim, recoupment, limitation or termination, or any breach or alleged breach by the Holder or any other Person of any obligation to the Company or any violation or alleged violation of law by the Holder or any other Person, and irrespective of any other circumstance which might otherwise limit such obligation of the Company to the Holder in connection with the issuance of Warrant Shares. Nothing herein shall limit a ▇▇▇▇▇▇'s right to pursue any other remedies available to it hereunder, at law or in equity including, without limitation, a decree of specific performance and/or injunctive relief with respect to the Company's failure to timely deliver Common Stock upon exercise of the Warrant as required pursuant to the terms hereof.

6.      Charges, Taxes and Expenses. Issuance and delivery of certificates for shares of Common Stock upon exercise of this Warrant shall be made without charge to the Holder for any issue or transfer tax, withholding tax, transfer agent fee or other incidental tax or expense in respect of the issuance of such certificates, all of which taxes and expenses shall be paid by the Company; provided, however, that the Company shall not be required to pay any tax which may be payable in respect of any transfer involved in the registration of any certificates for Warrant Shares or Warrants in a name other than that of the Holder or an Affiliate thereof. The Holder shall be responsible for all income tax liability that may arise as a result of holding or transferring this Warrant or receiving Warrant Shares upon exercise hereof.

7.      Replacement of Warrant. If this Warrant is mutilated, lost, stolen or destroyed, the Company shall issue or cause to be issued in exchange and substitution for and upon cancellation hereof, or in lieu of and substitution for this Warrant, a New Warrant, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction and customary and reasonable indemnity, if requested. Applicants for a New Warrant under such circumstances shall also comply with such other reasonable regulations and procedures and pay such other reasonable third-party costs as the Company may prescribe.

8.      Reservation of Warrant Shares. The Company covenants that it will at all times reserve and keep available out of the aggregate of its authorized but unissued and otherwise unreserved Common Stock, solely for the purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as herein provided, at least the number of Warrant Shares which are then issuable and deliverable upon the exercise of this entire Warrant, free from preemptive rights or any other contingent purchase rights of persons other than the Holder (taking into account the adjustments and restrictions of Section 9). The Company covenants that all Warrant Shares so issuable and deliverable shall, upon issuance and the payment of the applicable Exercise Price in accordance with the terms hereof, be duly and validly authorized, issued and fully paid and nonassessable. The Company will take all such action as may be necessary to assure that such shares of Common Stock may be issued as provided herein without violation of any applicable law or regulation, or of any requirements of any securities exchange or automated quotation system upon which the Common Stock may be listed.

9.      Certain Adjustments. The Exercise Price and number of Warrant Shares issuable upon exercise of this Warrant are subject to adjustment from time to time as set forth in this Section 9.

(a)      Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding, (i) pays a stock dividend on its Common Stock or otherwise makes a distribution on any class of capital stock that is payable in shares of Common Stock, (ii) subdivides outstanding shares of Common Stock into a larger number of shares, or (iii) combines outstanding shares of Common Stock into a smaller number of shares, then in each such case the Exercise Price shall be multiplied by a fraction of which the numerator shall be the number of shares of Common Stock outstanding immediately before such event and of which the denominator shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment made pursuant to clause (i) of this paragraph shall become effective immediately after the record date for the determination of shareholders entitled to receive such dividend or distribution, and any adjustment pursuant to clause (ii) or (iii) of this paragraph shall become effective immediately after the effective date of such subdivision or combination.

(b)      Pro Rata Distributions. If the Company, at any time while this Warrant is outstanding, distributes to holders of Common Stock (i) evidences of its indebtedness, (ii) any security (other than a distribution of Common Stock covered by the preceding paragraph), (iii) rights or warrants to subscribe for or purchase any security, (iv) any dividend or (v) any other asset or cash (in each case, "Distributed Property"), then in each such case:

(i)     the Exercise Price in effect immediately prior to the record date fixed for determination of shareholders entitled to receive such distribution shall be reduced (effective on such record date) to equal the product of such Exercise Price times a fraction of which the denominator shall be the average of the Closing Prices for the five Trading Days immediately prior to (but not including) such record date and of which the numerator shall be such average less the then fair market value of the Distributed Property distributed in respect of one outstanding share of Common Stock, as determined by the Company's independent certified public accountants that regularly examine the financial statements of the Company (an "Appraiser"). In such event, Holders holding Series F Warrants exercisable for a majority of the Common Stock issuable upon exercise of all Series F Warrants, after receipt of the determination by the Appraiser, shall have the right to select an additional appraiser (which shall be a nationally recognized accounting firm), in which case such fair market value shall be deemed to equal the average of the values determined by each of the Appraiser and such appraiser. As an alternative to the foregoing adjustment to the Exercise Price, at the request of the Holder delivered before the 90th day after such record date, the Company will deliver to the Holder, within five Trading Days after such request (or, if later, on the effective date of such distribution), the Distributed Property that the Holder would have been entitled to receive in respect of the Warrant Shares for which this Warrant could have been exercised immediately prior to such record date. If such Distributed Property is not delivered to a Holder pursuant to the preceding sentence, then upon expiration of or any exercise of the Warrant that occurs after such record date, such Holder shall remain entitled to receive, in addition to the Warrant Shares otherwise issuable upon such exercise (if applicable), such Distributed Property; and

(ii)     the number of Warrant Shares shall be increased to a number of shares equal to the number of shares of Common Stock obtainable immediately prior to the close of business on the record date fixed for the determination of holders of shares of Common Stock entitled to receive the Distributed Property multiplied by the reciprocal of the fraction set forth in the immediately preceding paragraph (i); provided that in the event that the Distribution is of shares of Common Stock (or common stock) ("Other Shares of Common Stock") of a company whose common shares are traded on a national securities exchange or a national automated quotation system, then the Holder may elect to receive a warrant to purchase Other Shares of Common Stock in lieu of an increase in the number of Warrant Shares, the terms of which shall be identical to those of this Warrant, except that such warrant shall be exercisable into the number of shares of Other Shares of Common Stock that would have been payable to the Holder pursuant to the distribution of the Distributed Property had the Holder exercised this Warrant immediately prior to such record date and with an aggregate exercise price equal to the product of the amount by which the exercise price of this Warrant was decreased with respect to the distribution of the Distributed Property pursuant to the terms of the immediately preceding paragraph (i) and the number of Warrant Shares calculated in accordance with the first part of this paragraph (ii).

(c)      Fundamental Transactions. If, at any time while this Warrant is outstanding the Company shall, directly or indirectly, in one or more related transactions, (i) effect any merger or consolidation of the Company with or into another Person in which the shareholders of the Company prior to the effective date of such transaction own less than 66 2/3% of the issued and outstanding voting rights and equity interests of the surviving corporation following the date of such transaction, (ii) effect any sale of 30% or more of its assets in one or a series of related transactions, (iii) engage in any tender offer or exchange offer (whether by the Company or another Person) is completed pursuant to which holders of Common Stock are permitted to tender or exchange their shares for other securities, cash or property, (iv) effect any reorganization, reclassification of the Common Stock or any compulsory share exchange pursuant to which the Common Stock is effectively converted into or exchanged for other securities, cash or property (other than as a result of a subdivision or combination of shares of Common Stock covered by Section 9(a) above), (v) engage in an acquisition after the date hereof by an individual or legal entity or "group" (as described in Rule 13d-5(b)(1) under the Exchange Act) of more than one-third of the voting rights or equity interests in the Company, (vi) replace more than one-half of the members of the Company's board of directors that is not approved by those individuals who are members of the board of directors on the date hereof (or other directors previously approved by such individuals); (vii) engage in a recapitalization, reorganization or other transaction involving the Company or any Subsidiary that constitutes or results in a transfer of more than one-half of the voting rights or equity interests in the Company; (viii) consummate a "Rule 13e-3 transaction" as defined in Rule 13e-3 under the Exchange Act with respect to the Company, or (ix) execute (or its controlling shareholders execute) of an agreement providing for or reasonably likely to result in any of the foregoing events (in any such case, a "Fundamental Transaction"), then the Holder shall have the right thereafter to receive, at the option of the Holder, (a) upon exercise of this Warrant, the same amount and kind of securities, cash or property as it would have been entitled to receive, upon the occurrence of such Fundamental Transaction if it had been, immediately prior to such Fundamental Transaction, the holder of the number of Warrant Shares then issuable upon exercise in full of this Warrant (the "Alternate Consideration") or (b) cash within five Trading Days after such election (or, if later, on the effective date of the Fundamental Transaction), equal to the Black-Scholes value of the remaining then unexercised portion of this Warrant on the date of such election. For purposes of any such exercise, the determination of the Exercise Price shall be appropriately adjusted to apply to such Alternate Consideration based on the amount of Alternate Consideration issuable in respect of one share of Common Stock in such Fundamental Transaction, and the Company shall apportion the Exercise Price among the Alternate Consideration in a reasonable manner reflecting the relative value of any different components of the Alternate Consideration. The aggregate Exercise Price for this Warrant will not be affected by any such Fundamental Transaction, but the Company shall apportion such aggregate Exercise Price among the Alternate Consideration in a reasonable manner reflecting the relative value of any different components of the Alternate Consideration. If holders of Common Stock are given any choice as to the securities, cash or property to be received in a Fundamental Transaction, then the Holder shall be given the same choice as to the Alternate Consideration it receives upon any exercise of this Warrant following such Fundamental Transaction. In the event of a Fundamental Transaction, the Company or the successor or purchasing Person, as the case may be, shall execute with the Holder a written agreement in form and substance reasonably satisfactory to the Holder providing that:

     (x)      this Warrant shall thereafter entitle the Holder to purchase the Alternate Consideration in accordance with this Section 9(c),

     (y)     in the case of any such successor or purchasing Person, upon such consolidation, merger, statutory exchange, combination, sale or conveyance such successor or purchasing Person shall be jointly and severally liable with the Company for the performance of all of the Company's obligations under this Warrant and the Purchase Agreement, and

     (z)     if registration or qualification is required under the Exchange Act or applicable state law for the public resale by the Holder of shares of stock and other securities so issuable upon exercise of this Warrant, such registration or qualification shall be completed prior to such reclassification, change, consolidation, merger, statutory exchange, combination or sale.

If, in the case of any Fundamental Transaction, the Alternate Consideration includes shares of stock, other securities, other property or assets of a Person other than the Company or any such successor or purchasing Person, as the case may be, in such Fundamental Transaction, then such written agreement shall also be executed by such other Person and shall contain such additional provisions to protect the interests of the Holder as the Board of Directors of the Company shall reasonably consider necessary by reason of the foregoing. At the Holder's request, any successor to the Company or surviving entity in such Fundamental Transaction shall issue to the Holder a new warrant consistent with the foregoing provisions and evidencing the Holder's right to purchase the Alternate Consideration for the aggregate Exercise Price upon exercise thereof. The terms of any agreement pursuant to which a Fundamental Transaction is effected shall include terms requiring any such successor or surviving entity to comply with the provisions of this paragraph (c) and insuring that the Warrant (or any such replacement security) will be similarly adjusted upon any subsequent transaction analogous to a Fundamental Transaction.

(d)      Subsequent Equity Sales.

(i)     If, at any time while this Warrant is outstanding, the Company or any Subsidiary issues additional shares of Common Stock or rights, warrants, options or other securities or debt convertible, exercisable or exchangeable for shares of Common Stock or otherwise entitling any Person to acquire shares of Common Stock (collectively, "Common Stock Equivalents") at a price per share of Common Stock (the "Effective Price") less than the Exercise Price (as adjusted hereunder to such date), then the Exercise Price shall be reduced to equal the Effective Price. If, at any time while this Warrant is outstanding, the Company or any Subsidiary issues Common Stock or Common Stock Equivalents at an Effective Price greater than the Exercise Price (as adjusted hereunder to such date) but less than the average Closing Price over the five Trading Days prior to such issuance (the "Adjustment Price"), then the Exercise Price shall be reduced to equal the product of (A) the Exercise Price in effect immediately prior to such issuance of Common Stock or Common Stock Equivalents times (B) a fraction, the numerator of which is the sum of (1) the number of shares of Common Stock outstanding immediately prior to such issuance, plus (2) the number of shares of Common Stock which the aggregate Effective Price of the Common Stock issued (or deemed to be issued) would purchase at the Adjustment Price, and the denominator of which is the aggregate number of shares of Common Stock outstanding or deemed to be outstanding immediately after such issuance. For purposes of this paragraph, in connection with any issuance of any Common Stock Equivalents, (A) the maximum number of shares of Common Stock potentially issuable at any time upon conversion, exercise or exchange of such Common Stock Equivalents (the "Deemed Number") shall be deemed to be outstanding upon issuance of such Common Stock Equivalents, (B) the Effective Price applicable to such Common Stock shall equal the minimum dollar value of consideration payable to the Company to purchase such Common Stock Equivalents and to convert, exercise or exchange them into Common Stock, divided by the Deemed Number, and (C) no further adjustment shall be made to the Exercise Price upon the actual issuance of Common Stock upon conversion, exercise or exchange of such Common Stock Equivalents.

(ii)     If, at any time while this Warrant is outstanding, the Company or any Subsidiary issues Common Stock Equivalents with an Effective Price or a number of underlying shares that floats or resets or otherwise varies or is subject to adjustment based (directly or indirectly) on market prices of the Common Stock (a "Floating Price Security"), then for purposes of applying the preceding paragraph in connection with any subsequent exercise, the Effective Price will be determined separately on each Exercise Date and will be deemed to equal the lowest Effective Price at which any holder of such Floating Price Security is entitled to acquire Common Stock on such Exercise Date (regardless of whether any such holder actually acquires any shares on such date).

(iii)     Notwithstanding the foregoing, no adjustment will be made under this paragraph (d) in respect of any Excluded Stock.

(iv)     Unless and until such time as the Company receives the Company Shareholder Approval, no adjustment pursuant to Section 9(e) shall cause the Exercise Price to be less than $2.01, as adjusted for any stock dividend, stock split, stock combination, reclassification or similar transaction (the "Exercise Floor Price").

(e)      Number of Warrant Shares. Simultaneously with any adjustment to the Exercise Price pursuant to paragraphs (a), (b) or (d) of this Section, the number of Warrant Shares that may be purchased upon exercise of this Warrant shall be increased or decreased proportionately, so that after such adjustment the aggregate Exercise Price payable hereunder for the increased or decreased number of Warrant Shares shall be the same as the aggregate Exercise Price in effect immediately prior to such adjustment.

(f)      Calculations. All calculations under this Section 9 shall be rounded up to the nearest cent or the nearest share, as applicable. The number of shares of Common Stock outstanding at any given time shall not include shares owned or held by or for the account of the Company, and the disposition of any such shares shall be considered an issue or sale of Common Stock.

(g)      Notice of Adjustments. Upon the occurrence of each adjustment pursuant to this Section 9, the Company at its expense will promptly compute such adjustment in accordance with the terms of this Warrant and prepare a certificate setting forth such adjustment, including a statement of the adjusted Exercise Price and adjusted number or type of Warrant Shares or other securities issuable upon exercise of this Warrant (as applicable), describing the transactions giving rise to such adjustments and showing in detail the facts upon which such adjustment is based. Upon written request, the Company will promptly deliver a copy of each such certificate to the Holder and to the Company's Transfer Agent.

(h)      Notice of Corporate Events. If the Company (i) declares a dividend or any other distribution of cash, securities or other property in respect of its Common Stock, including without limitation any granting of rights or warrants to subscribe for or purchase any capital stock of the Company or any Subsidiary, (ii) authorizes or approves, enters into any agreement contemplating or solicits shareholder approval for any Fundamental Transaction or (iii) authorizes the voluntary dissolution, liquidation or winding up of the affairs of the Company, then the Company shall deliver to the Holder a notice describing the material terms and conditions of such transaction, at least 20 calendar days prior to the applicable record or effective date on which a Person would need to hold Common Stock in order to participate in or vote with respect to such transaction, and the Company will take all steps reasonably necessary in order to insure that the Holder is given the practical opportunity to exercise this Warrant prior to such time so as to participate in or vote with respect to such transaction; provided, however, that the failure to deliver such notice or any defect therein shall not affect the validity of the corporate action required to be described in such notice.

(i)      Other Events. If any event occurs of the type contemplated by the provisions of this Section 9 but not expressly provided for by such provisions (including, without limitation, the granting of stock appreciation rights, phantom stock rights or other rights with equity features), then the Company's board of directors will make an appropriate adjustment in the Exercise Price and the number of Warrant Shares so as to protect the rights of the Holder; provided that no such adjustment pursuant to this Section 9(i) will increase the Exercise Price or decrease the number of Warrant Shares as otherwise determined pursuant to this Section 9.

10.      Payment of Exercise Price. The Holder shall pay the Exercise Price (i) in immediately available funds or (ii) if elected by the Holder, the Holder may satisfy its obligation to pay the Exercise Price through a "cashless exercise," in which event the Company shall issue to the Holder the number of Warrant Shares determined as follows:

          For purposes of Rule 144 promulgated under the Securities Act, it is intended, understood and acknowledged that the Warrant Shares issued in a cashless exercise transaction shall be deemed to have been acquired by the Holder, and the holding period for the Warrant Shares shall be deemed to have commenced, on the date this Warrant was originally issued pursuant to the Purchase Agreement.

11.      Limitation on Exercise. (a) Notwithstanding anything to the contrary contained herein, the number of shares of Common Stock that may be acquired by the Holder upon any exercise of this Warrant (or otherwise in respect hereof) shall be limited to the extent necessary to insure that, following such exercise (or other issuance), the total number of shares of Common Stock then beneficially owned by such Holder and any other Persons whose beneficial ownership of Common Stock would be aggregated with the Holder's for purposes of Section 13(d) of the Exchange Act, does not exceed 4.99% (the "Maximum Percentage") of the total number of issued and outstanding shares of Common Stock (including for such purpose the shares of Common Stock issuable upon such exercise). For such purposes, beneficial ownership shall be determined in accordance with Section 13(d) of the Exchange Act and the rules and regulations promulgated thereunder. Each delivery of an Exercise Notice hereunder will constitute a representation by the Holder that it has evaluated the limitation set forth in this paragraph and determined that issuance of the full number of Warrant Shares requested in such Exercise Notice is permitted under this paragraph. The Company's obligation to issue shares of Common Stock in excess of the limitation referred to in this Section shall be suspended (and shall not terminate or expire notwithstanding any contrary provisions hereof) until such time, if any, as such shares of Common Stock may be issued in compliance with such limitation. The Holder shall have the right at any time and from time to time, to waive the provisions of this Section and to increase the Maximum Percentage (but not in excess of 9.9%) unless the Holder shall have, by written instrument delivered to the Company, irrevocably waived its rights to so increase its Maximum Percentage, but (i) any such waiver or increase will not be effective until the 61st day after such notice is delivered to the Company, and (ii) any such waiver or increase will apply only to the Holder and not to any other holder of Warrants. For any reason at any time, upon the written or oral request of the Holder, the Company shall within one (1) Business Day confirm orally and in writing to the Holder the number of shares of Common Stock then outstanding.

(b)     If the Company has not previously obtained Company Shareholder Approval, then the Company may not issue shares of Common Stock in excess of the Issuable Maximum upon exercise of the Warrants. The "Issuable Maximum" means a number of shares equal to 19.99% of the Company's outstanding shares on the First Closing Date. Each Holder (or such ▇▇▇▇▇▇'s successor in interest) shall be entitled to a portion of the Issuable Maximum (and any amounts to be paid in excess thereof) equal to the quotient obtained by dividing: (x) the principal amount of Debentures issued and sold to such Holder at the First Closing and the Second Closing by (y) the aggregate principal amount of Debentures issued and sold by the Company at the First Closing and the Second Closing. If any Holder (or such ▇▇▇▇▇▇'s successor in interest) shall no longer hold Debentures or Warrants, then such Holder's remaining portion of the Issuable Maximum (and any amounts to be paid in excess thereof) shall be allocated pro-rata among the remaining Holders. If on any Exercise Date: (A) the sum of (I) the aggregate number of shares of Common Stock that would then be issuable upon exercise in full of all then outstanding Warrants and conversion in full of all then outstanding principal amount and accrued interest on the Debentures and (II) all shares of Common Stock previously issued pursuant to any of the Debentures and Warrants, would exceed the Issuable Maximum, and (B) the Company shall not have previously obtained Company Shareholder Approval, then, (with respect to such exercise) the Company shall issue to the exercising Holder the lesser of (i) the number of shares of Common Stock to be issued pursuant to the Exercise Notice and (ii) a number of shares of Common Stock equal to such Holder's pro-rata portion (which shall be calculated pursuant to the terms hereof) of the Issuable Maximum less all Underlying Shares previously issued under the Debentures and the Warrants to such Holder. The Company and the Holder understand and agree that shares of Common Stock issued to and then held by the Holder as a result of exercises of Warrants shall not be entitled to cast votes on any resolution to obtain Company Shareholder Approval pursuant hereto. The Company and the Holder acknowledge and agree that this Section 11(b) is meant to work in conjunction with Section 6(b)(iii) under the Debentures so that in no instance are Underlying Shares issued so that the aggregate amount of Common Stock issued hereunder and thereunder exceeds the Issuable Maximum unless the Company has obtained Company Shareholder Approval.

12.      Fractional Shares. The Company shall not be required to issue or cause to be issued fractional Warrant Shares on the exercise of this Warrant. If any fraction of a Warrant Share would, except for the provisions of this Section, be issuable upon exercise of this Warrant, the number of Warrant Shares to be issued will be rounded up to the nearest whole share.

13.      Notices. Any and all notices or other communications or deliveries hereunder (including without limitation any Exercise Notice) shall be in writing and shall be deemed given and effective on the earliest of (i) the date of transmission, if such notice or communication is delivered via facsimile at the facsimile number specified in this Section prior to 6:30 p.m. (New York City time) on a Trading Day, (ii) the next Trading Day after the date of transmission, if such notice or communication is delivered via facsimile at the facsimile number specified in this Section on a day that is not a Trading Day or later than 6:30 p.m. (New York City time) on any Trading Day, (iii) the Trading Day following the date of mailing, if sent by nationally recognized overnight courier service, or (iv) upon actual receipt by the party to whom such notice is required to be given. The address for such notices or communications shall be as set forth in the Purchase Agreement.

14.      Warrant Agent. The Company shall serve as warrant agent under this Warrant. Upon 30 days' notice to the Holder, the Company may appoint a new warrant agent. Any corporation into which the Company or any new warrant agent may be merged or any corporation resulting from any consolidation to which the Company or any new warrant agent shall be a party or any corporation to which the Company or any new warrant agent transfers substantially all of its corporate trust or shareholders services business shall be a successor warrant agent under this Warrant without any further act. Any such successor warrant agent shall promptly cause notice of its succession as warrant agent to be mailed (by first class mail, postage prepaid) to the Holder at the Holder's last address as shown on the Warrant Register.

15.      Miscellaneous.

(a)      Subject to the restrictions on transfer set forth on the first page hereof, this Warrant may be assigned by the Holder. This Warrant may not be assigned by the Company except to a successor in the event of a Fundamental Transaction in compliance with Section 9(c). This Warrant shall be binding on and inure to the benefit of the parties hereto and their respective successors and assigns. Subject to the preceding sentence, nothing in this Warrant shall be construed to give to any Person other than the Company and the Holder any legal or equitable right, remedy or cause of action under this Warrant. This Warrant may be amended only in writing signed by the Company and the Holder or, if applicable, their successors and assigns.

(b)      The Company will not, by amendment of its governing documents or through any reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the Holder against impairment. Without limiting the generality of the foregoing, the Company (i) will not increase the par value of any Warrant Shares above the amount payable therefor on such exercise, (ii) will take all such action as may be reasonably necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares on the exercise of this Warrant, and (iii) will not close its shareholder books or records in any manner which interferes with the timely exercise of this Warrant.

(c)       GOVERNING LAW; VENUE; WAIVER OF JURY TRIAL. ALL QUESTIONS CONCERNING THE CONSTRUCTION, VALIDITY, ENFORCEMENT AND INTERPRETATION OF THIS WARRANT SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK. EACH PARTY HEREBY IRREVOCABLY SUBMITS TO THE EXCLUSIVE JURISDICTION OF THE STATE AND FEDERAL COURTS SITTING IN THE CITY OF NEW YORK, BOROUGH OF MANHATTAN, FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN CONNECTION HEREWITH OR WITH ANY TRANSACTION CONTEMPLATED HEREBY OR DISCUSSED HEREIN (INCLUDING WITH RESPECT TO THE ENFORCEMENT OF ANY OF THE TRANSACTION DOCUMENTS), AND HEREBY IRREVOCABLY WAIVES, AND AGREES NOT TO ASSERT IN ANY SUIT, ACTION OR PROCEEDING, ANY CLAIM THAT IT IS NOT PERSONALLY SUBJECT TO THE JURISDICTION OF ANY SUCH COURT, THAT SUCH SUIT, ACTION OR PROCEEDING IS IMPROPER. EACH PARTY HEREBY IRREVOCABLY WAIVES PERSONAL SERVICE OF PROCESS AND CONSENTS TO PROCESS BEING SERVED IN ANY SUCH SUIT, ACTION OR PROCEEDING BY MAILING A COPY THEREOF VIA REGISTERED OR CERTIFIED MAIL OR OVERNIGHT DELIVERY (WITH EVIDENCE OF DELIVERY) TO SUCH PARTY AT THE ADDRESS IN EFFECT FOR NOTICES TO IT UNDER THIS AGREEMENT AND AGREES THAT SUCH SERVICE SHALL CONSTITUTE GOOD AND SUFFICIENT SERVICE OF PROCESS AND NOTICE THEREOF. NOTHING CONTAINED HEREIN SHALL BE DEEMED TO LIMIT IN ANY WAY ANY RIGHT TO SERVE PROCESS IN ANY MANNER PERMITTED BY LAW. EACH PARTY HEREBY WAIVES ALL RIGHTS TO A TRIAL BY JURY.

(d)      The headings herein are for convenience only, do not constitute a part of this Warrant and shall not be deemed to limit or affect any of the provisions hereof.

(e)      In case any one or more of the provisions of this Warrant shall be invalid or unenforceable in any respect, the validity and enforceability of the remaining terms and provisions of this Warrant shall not in any way be affected or impaired thereby and the parties will attempt in good faith to agree upon a valid and enforceable provision which shall be a commercially reasonable substitute therefor, and upon so agreeing, shall incorporate such substitute provision in this Warrant.

[REMAINDER OF ▇▇▇▇ INTENTIONALLY LEFT BLANK,
SIGNATURE PAGE FOLLOWS]

IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by its authorized officer as of the date first indicated above.

FORM OF EXERCISE NOTICE

(To be executed by the Holder to exercise the right to purchase shares of Common Stock under the foregoing Warrant)

To: ▇▇▇▇▇▇▇▇▇▇ LABORATORIES, INC.

The undersigned is the Holder of Warrant No. _______ (the "Warrant") issued by ▇▇▇▇▇▇▇▇▇▇ Laboratories, Inc., a Texas corporation (the "Company"). Capitalized terms used herein and not otherwise defined have the respective meanings set forth in the Warrant.

FORM OF ASSIGNMENT

[To be completed and signed only upon transfer of Warrant]

FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto ________________________________ the right represented by the within Warrant to purchase ____________ shares of Common Stock of ▇▇▇▇▇▇▇▇▇▇ Laboratories, Inc. to which the within Warrant relates and appoints ________________ attorney to transfer said right on the books of ▇▇▇▇▇▇▇▇▇▇ Laboratories, Inc. with full power of substitution in the premises.