Document:

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                                                                   Exhibit 10.50

                             FIRST AMENDMENT TO THE
                           LOAN EXTENSION AND RELEASE
                              AND WAIVER AGREEMENT

     This First Amendment to the Loan Extension and Release and Waiver Agreement
(this "Amendment") is entered into by and between Polar Molecular Corporation, a
Delaware corporation (the "Company"), and Affiliated Investments L.L.C., a
Michigan limited liability company (the "Holder"), to be effective as of May 31,
2002.

                                    RECITALS

A.   The Company and the Holder have entered into a Loan Extension and Release
     and Waiver Agreement (the "Original Loan Extension"); and

B.   The Company and the Holder now wish to amend certain terms of the Original
     Loan Extension.

C.   The parties hereto acknowledge that the Company made a payment of principal
     and interest in the amount of $50,000 at the end of February of 2002 on the
     Note (as defined in the Original Loan Extension), and that the balance owed
     on the Note as of June 1, 2002 is $591,220 (consisting of $574,000 in
     principal and $17,220 in interest).

                                    AGREEMENT

     In consideration of the foregoing and the mutual promises contained herein,
the Holder and the Company hereby agree as follows:

1.   Paragraph 1 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "1.  Extension of Due Date. The final maturity date of December 26, 2001
          (the "Original Due Date") set forth in the Note is hereby extended to
          October 1, 2002, subject to the other repayment terms set forth
          herein."

2.   Paragraph 2 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "2.  Terms of Repayment. The Company shall repay principal and interest
          amounts outstanding under the Note in accordance with the payment
          schedule attached hereto as Exhibit A. Notwithstanding the terms of
          the payment schedule set forth in Exhibit A hereto, the Company may
          prepay principal and interest without premium or penalty. All payments
          to be made pursuant to this Agreement are in addition to the principal
          amount of $9,900, which the Company owes to the Holder for
          reimbursement of attorney fees pursuant to the terms of the Purchase
          Agreement between the Company and Holder, dated as of October 25,
          2001. Such reimbursement for attorney's fees will be paid to the
          Holder in increments of $3,300 on or before each of June 15, 2002,
          July 15, 2002 and August 15, 2002"

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3.   Paragraph 3 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "3.  Consideration. As consideration for entering into this Agreement, the
          Company shall issue the Holder 50,000 shares of the Company's common
          stock for each month that the obligations under this Agreement remain
          outstanding, up to an aggregate of 450,000 shares. Additionally, as
          consideration for entering into this Amendment, the Company shall
          deliver to the Holder a stock certificate representing 17,000 shares
          of the Company's common stock. The Holder acknowledges receipt of the
          stock certificates due to it for the months of January through May of
          2002, representing in the aggregate 250,000 shares of the Company's
          common stock. A certificate representing 17,000 shares of the
          Company's common stock will be delivered to the Holder upon due
          execution of this Agreement, and an additional certificate
          representing 50,000 shares of the Company's common stock will be
          issued to the Holder upon each monthly anniversary of the Original Due
          Date, until the earlier of (i) repayment in full of the obligations
          hereunder, or (ii) such time as the Company has issued the Holder an
          aggregate of 467,000 shares of the Company's common stock pursuant to
          this Agreement."

4.   Paragraph 3 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "3.  The Company will pay the remaining balance of principal and interest
          on or prior to October 1, 2002."

5.   No Other Changes. Except as explicitly amended by this Amendment, all of
     the terms and conditions of the Original Loan Extension shall remain in
     full force and effect.

                            [SIGNATURE PAGE FOLLOWS]

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     The undersigned have executed this Amendment to be effective as of the date
set forth herein.

COMPANY:

POLAR MOLECULAR CORPORATION

By: /s/ Mark L. Nelson
    ------------------------------------
        Mark L. Nelson, President and
        Chief Executive Officer

HOLDER:

AFFILIATED INVESTMENTS, L.L.C.
Address: 2750 Auburn Court
         Auburn Hills, MI 48236
Fax:     248-852-5174

By: /s/    Bruce Becker
    -----------------------------------
    Name:  Bruce Becker
    Title: President<PAGE>

                                                                   Exhibit 10.51

                             SECOND AMENDMENT TO THE
                           LOAN EXTENSION AND RELEASE
                              AND WAIVER AGREEMENT

     This Second Amendment to the Loan Extension and Release and Waiver
Agreement (this "Amendment") is entered into by and between Polar Molecular
Corporation, a Delaware corporation (the "Company"), and Affiliated Investments
L.L.C., a Michigan limited liability company (the "Holder"), to be effective as
of October 1, 2002.

                                    RECITALS

A.   The Company and the Holder have entered into a Loan Extension and Release
     and Waiver Agreement, as amended by the First Amendment thereto (the
     "Original Loan Extension"); and

B.   The Company and the Holder now wish to amend certain terms of the Original
     Loan Extension.

C.   The parties hereto acknowledge that the Company made a payment of principal
     and interest in the amount of $50,000 at the end of February of 2002 on the
     Note (as defined in the Original Loan Extension), and that the balance owed
     on the Note as of October 1, 2002 is $614,180 (consisting of $574,000 in
     principal and $40,180 in interest).

                                    AGREEMENT

     In consideration of the foregoing and the mutual promises contained herein,
the Holder and the Company hereby agree as follows:

1.   Paragraph 1 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "1.  Extension of Due Date. The final maturity date of December 26, 2001
          (the "Original Due Date") set forth in the Note is hereby extended to
          June 30, 2003, subject to the other repayment terms set forth herein."

2.   Paragraph 2 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "2.  Terms of Repayment. The Company shall repay principal and interest
          amounts outstanding under the Note in accordance with the payment
          schedule attached hereto as Exhibit A. Notwithstanding the terms of
          the payment schedule set forth in Exhibit A hereto, the Company may
          prepay principal and interest without premium or penalty."

3.   Paragraph 3 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

<PAGE>

     "3.  Consideration. Holder acknowledges receipt of the stock certificates
          and the shares of the common stock of the Company reflected on Exhibit
          B hereto as consideration for entering into the Original Loan
          Extension, as amended to date. As additional consideration for
          entering into the Original Loan Extension, as amended to date, the
          Company hereby agrees to pay Holder an additional sum of $50,000,
          which sum is to be paid within, and shall not be deemed to be in
          arrears until June 30, 2003. While the parties acknowledge that this
          additional consideration amount effectively increases the interest
          rate on the Note, in no case (including, without limitation
          calculation of default interest on the Note) shall such $50,000 be
          compounded as outstanding interest on the Note or shall interest
          accrue in any circumstance against such $50,000."

4.   Paragraph 5 of the Original Loan Extension is hereby amended in its
     entirety to read as follows:

     "5.  Effective Date. The Effective Date of this Agreement is February 28,
          2002. The Holder hereby agrees not to exercise any remedy that may be
          available to it for non-payment of the Note, including without
          limitation, exercising its remedies under the Note or the Security
          Agreement until June 30, 2003."

5.   The Original Loan Extension is hereby amended by adding a new Paragraph 9
     to the end thereof to read in its entirety as follows:

     "9.  Interest Compounding. Notwithstanding anything in the Note, on March
          1, 2003 all accrued interest remaining outstanding as of such date
          shall be compounded and added to the principal amount of the Note.
          Notwithstanding the face value of the Note, after March 1, 2003,
          interest shall accrue on the principal amount of the Note recalculated
          in accordance herewith at the rate and as prescribed by the terms of
          the Note."

6.   Receipt of Stock Certificate. Holder acknowledges receipt of stock
     certificate no.      reflecting an additional issuance of 50,000 shares of
                     ----
     the common stock of the Company in favor of Holder in connection with
     entering into this Amendment.

7.   No Other Changes. Except as explicitly amended by this Amendment, all of
     the terms and conditions of the Original Loan Extension shall remain in
     full force and effect.

                            [SIGNATURE PAGE FOLLOWS]

                                       2

<PAGE>

     The undersigned have executed this Amendment to be effective as of the date
set forth herein.

COMPANY:

POLAR MOLECULAR CORPORATION

By: /s/ Mark L. Nelson
    ------------------------------------
        Mark L. Nelson, President and
        Chief Executive Officer

HOLDER:

AFFILIATED INVESTMENTS, L.L.C.
Address: 2750 Auburn Ct
         Auburn Hills, MI 48236
Fax:     248-852-5174

By: /s/    Bruce Becker
    ------------------------------------
    Name:  Bruce Becker
    Title: President

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