THIS INSTRUMENT IS SECURED BY A DEED OF TRUST, ASSIGNMENT OF PERMITS,
     RENTS AND BENEFITS, SECURITY AGREEMENT AND FIXTURE FILING, DATED AS OF
     JUNE 5, 1991.


                      FOURTH AMENDMENT TO CREDIT AGREEMENT


          FOURTH AMENDMENT dated as of September 23, 1994 TO CREDIT AGREEMENT
dated as of March 20, 1991 among RHEOX, INC., a Delaware corporation (the
"Company"); RHEOX INTERNATIONAL, INC., a Delaware corporation (the "Subsidiary
Guarantor"); each of the lenders that is a signatory hereto (individually, a
"Bank" and, collectively, the "Banks"); THE CHASE MANHATTAN BANK (NATIONAL
ASSOCIATION), a national banking association, and THE NIPPON CREDIT BANK, LTD.,
a Japanese banking corporation acting through its New York branch, as co-agents
for the Banks (each in such capacity, a "Co-Agent" and, collectively, the "Co-
Agents"); and THE CHASE MANHATTAN BANK (NATIONAL ASSOCIATION), as administrative
agent for the Banks (in such capacity, together with its successors in such
capacity, the "Administrative Agent"). 

          WHEREAS, the parties hereto are parties to a Credit Agreement dated as
of March 20, 1991 among the Company, the Subsidiary Guarantor, the Banks, the
Co-Agents and the Administrative Agent (as at any time amended or otherwise
modified, the "Credit Agreement"; terms defined therein having their respective
defined meanings when used herein unless otherwise defined herein);

          WHEREAS, the Company has requested that the Credit Agreement be
amended, and the Banks are willing to consent to such amendment upon the terms
and conditions contained herein.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

          SECTION 1.  AMENDMENTS.  The Credit Agreement is hereby amended
(effective as provided in Section 3 hereof) as follows:

          A.  The first sentence of the definition of "Revolving Credit
     Termination Date" in Section 1.01 of the Credit Agreement is amended
     to read as follows:

               "Revolving Credit Termination Date" shall mean
          September 23, 1995.

     In that connection, each Revolving Credit Bank confirms its
     participation in the Letter of Credit issued by Chase pursuant to the
     Credit Agreement outstanding on March 20,1994 (which Letter of Credit
     remains outstanding on the date hereof) and its obligations under
     Section 2.10 of the Credit Agreement (and the Company confirms its
     obligations under said Section 2.10) with respect to such Letter of
     Credit as if such Letter of Credit had been (and all parties hereto
     agree that such Letter of Credit shall be deemed, for all purposes of
     the Credit Agreement and the other Credit Documents to have been) out-
     standing under the Credit Agreement at all times during the period
     commencing on March 20, 1994 through the date upon which this Section
     1 becomes effective as provided in Section 3 hereof (the "Effective
     Date") and at all times thereafter; provided that the commitment fee
     provided for by Section 2.04(b) of the Credit Agreement, and the
     letter of credit fee of 21/4% per annum provided for by
     Section 2.10(g) of the Credit Agreement, shall not be payable for the
     period commencing on March 20, 1994 and ending on the day preceding
     the Effective Date.

          B.  Section 12.04 of the Credit Agreement is amended by inserting
     the following immediately before the comma at the end of clause (i)(a)
     thereof:

          (except for extensions of the Revolving Credit Termination
          Date as provided in the definition of such term in Section
          1.01 hereof).

          C.  Anything in the Credit Agreement to the contrary
     notwithstanding:

               (i)  Any Bank (x) that is not a citizen or resident of the
          United States of America, a corporation, partnership or other
          entity created or organized in or under any laws of the United
          States of America, or any estate or trust that is subject to
          Federal income taxation regardless of the source of its income,
          (y) that is not a "bank" within the meaning of section
          881(c)(3)(A) of the U.S. Internal Revenue Code and (z) that could
          become completely exempt from withholding of any tax, assessment
          or other charge or levy imposed by or on behalf of the United
          States of America or any taxing authority thereof ("U.S. Taxes")
          in respect of payment of any obligations due to such Bank under
          the Credit Agreement ("Obligations") if the Obligations were in
          registered form for U.S. Federal income tax purposes (a "Non-U.S.
          Bank") may request the Company (through the Administrative
          Agent), and the Company agrees thereupon, to record on the
          Register referred to in paragraph (d) below any Obligations held
          by such Non-U.S. Bank.   

              (ii)  Obligations recorded on the Register ("Registered
          Obligations") may not be evidenced by promissory notes other than
          Registered Notes (as defined below) and, upon the registration of
          any Obligation, any Note or Notes (other than a Registered Note)
          evidencing the same shall be null and void and shall be returned
          to the Company.  The Company agrees, at the request of any Non-
          U.S. Bank holding any Registered Obligation(s) (a copy of which
          shall be sent to the Administrative Agent), to issue promissory
          note(s) registered as provided in paragraph (d) below (each, a
          "Registered Note") to evidence such Registered Obligation(s);
          each such note shall be in the form of Exhibit A-2 to the Credit
          Agreement appropriately modified to reflect the provisions of
          this paragraph C (and each such note shall be deemed to be a
          "Term Loan Note" for all purposes of the Credit Agreement and the
          other Credit Documents).  An Obligation once recorded on the
          Register may not be removed from the Register as long as it
          remains outstanding and a Registered Note may not be exchanged
          for a promissory note that is not a Registered Note.  Registered
          Notes may be surrendered to the Company for cancellation so that
          the Registered Obligations that were evidenced thereby are no
          longer evidenced by any promissory notes.

             (iii)  Each Non-U.S. Bank holding Registered Obligations (a
          "Registered Holder") (or, if such Registered Holder is not the
          beneficial owner thereof, such beneficial owner) shall, if
          legally entitled to do so, deliver to the Company prior to or at
          the time such Non-U.S. Bank becomes a Registered Holder a Form W-
          8 (Certificate of Foreign Status of the U.S. Department of
          Treasury) (or any successor or related form adopted by the U.S.
          taxing authorities), together with an annual certificate stating
          that (x) such Registered Holder (or beneficial owner, as the case
          may be) is not a "bank" within the meaning of section
          881(c)(3)(A) of the U.S. Internal Revenue Code and (y) such
          Registered Holder (or beneficial owner, as the case may be) shall
          promptly notify the Company if at any time such Registered Holder
          (or beneficial owner, as the case may be) determines that it is
          no longer in a position to provide such certification to the

          Company (or any other form of certification adopted by the U.S.
          taxing authorities for such purposes).

              (iv)  At the request of any Non-U.S. Bank the Company shall
          maintain, or cause to be maintained, a register (the "Register")
          (which, at the request of the Company, shall be kept by the
          Administrative Agent on behalf of the Company at no extra charge
          to the Company at the address to which notices to the
          Administrative Agent are to be sent under the Credit Agreement)
          on which it enters the name of the Registered Holder of
          Registered Obligation(s) (and any Registered Note evidencing the
          same).  A Registered Obligation (and any Registered Note
          evidencing the same) may be assigned or otherwise transferred in
          whole or in part only by registration of the assignment or
          transfer of such Registered Obligation (and any Registered Note
          evidencing the same) on the Register (and each Registered Note
          shall expressly so provide).  Any assignment or transfer of all
          or part of such Registered Obligation (and any Registered Note
          evidencing the same) shall be registered on the Register only
          upon presentment for registration of a written instrument of
          assignment or transfer of such Registered Obligation duly
          executed by the Registered Holder (together with surrender of any
          Registered Note evidencing such Registered Obligation, duly
          endorsed by (or accompanied by a written instrument of assignment
          or transfer duly executed by) the Registered Holder thereof, and
          thereupon one or more new Registered Note(s) in the same
          aggregate principal amount shall be issued to the designated
          assignee(s) or transferee(s)).  Prior to such due presentment for
          registration of assignment or transfer, the Company and the
          Administrative Agent shall treat the Person in whose name such
          Registered Obligation (and any Registered Note evidencing the
          same) is registered as the owner thereof for the purpose of
          receiving all payments thereon and for all other purposes,
          notwithstanding any notice to the contrary.

               (v)  The Register shall be available for inspection by the
          Company and any Bank at any reasonable time upon reasonable prior
          notice.

          D.  Each reference in the Credit Agreement and the other Credit
     Documents to the Credit Agreement shall be deemed to be a reference to
     the Credit Agreement as amended hereby.  Except as expressly provided
     in this Section 1, the Credit Agreement shall remain unchanged and in
     full force and effect.

          SECTION 2.  REPRESENTATIONS AND WARRANTIES.  Each of the Company and
the Subsidiary Guarantor represents and warrants that:

          A.  The execution and delivery of this Amendment by it has been duly
authorized by all necessary corporate action on its part.

          B.  This Amendment has been duly executed and delivered by it, and
each of this Amendment and the Credit Agreement as modified hereby constitutes
its legal, valid and binding obligation enforceable in accordance with its
respective terms subject, however, to the application by a court of general
principles of equity and to the effect of any applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' rights
generally.

          SECTION 3.  EFFECTIVENESS.  The provisions of Section 1 hereof shall
become effective on the date by which counterparts hereof have been duly
executed by the Company, the Subsidiary Guarantor, the Banks and the
Administrative Agent and delivered to the Administrative Agent and the
Administrative Agent has received evidence reasonably satisfactory to it as to
the truth of the representation contained in Section 2.A hereof.

          SECTION 4.  COUNTERPARTS.  This Amendment may be executed in any
number of counterparts, each of which may be deemed an original but all of which
together shall constitute one and the same instrument.

          SECTION 5.  GOVERNING LAW.  This Amendment shall be governed and
construed in accordance with the laws of the State of New York.

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed by their respective officers duly authorized as of the date first
above written.

RHEOX, INC.


By                            
  Name:
  Title:

RHEOX INTERNATIONAL, INC.


By______________________________
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION), as
   Co-Agent and
   Administrative Agent 


By_____________________________
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.,
  as Co-Agent


By_____________________________
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION)


By_____________________________
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.


By_____________________________
  Name:
  Title:

VAN KAMPEN MERRITT PRIME
  RATE INCOME TRUST


By_____________________________
  Name:
  Title:

CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., as Investment
  Advisor to:

RESTRUCTURED OBLIGATIONS BACKED
  BY SENIOR ASSETS B.V.


By_____________________________
  Name:
  Title:

GIROCREDIT BANK,
  NEW YORK BRANCH


By_____________________________
  Name:
  Title:

BANQUE PARIBAS


By_____________________________
  Name:
  Title:


     THIS INSTRUMENT IS SECURED BY A DEED OF TRUST, ASSIGNMENT OF PERMITS,
     RENTS AND BENEFITS, SECURITY AGREEMENT AND FIXTURE FILING, DATED AS OF
     JUNE 5, 1991.


                       FIFTH AMENDMENT TO CREDIT AGREEMENT


          FIFTH AMENDMENT dated as of December 15, 1994 TO CREDIT AGREEMENT
dated as of March 20, 1991 among RHEOX, INC., a Delaware corporation (the
"Company"); RHEOX INTERNATIONAL, INC., a Delaware corporation (the "Subsidiary
Guarantor"); each of the lenders that is a signatory hereto (individually, a
"Bank" and, collectively, the "Banks"); THE CHASE MANHATTAN BANK (NATIONAL
ASSOCIATION), a national banking association, and THE NIPPON CREDIT BANK, LTD.,
a Japanese banking corporation acting through its New York branch, as co-agents
for the Banks (each in such capacity, a "Co-Agent" and, collectively, the "Co-
Agents"); and THE CHASE MANHATTAN BANK (NATIONAL ASSOCIATION), as administrative
agent for the Banks (in such capacity, together with its successors in such
capacity, the "Administrative Agent"). 

          WHEREAS, the parties hereto are parties to a Credit Agreement dated as
of March 20, 1991 among the Company, the Subsidiary Guarantor, the Banks, the
Co-Agents and the Administrative Agent (as at any time amended or otherwise
modified, the "Credit Agreement"; terms defined therein having their respective
defined meanings when used herein unless otherwise defined herein);

          WHEREAS, the Company has requested that the Credit Agreement be
amended, and the Banks are willing to consent to such amendment upon the terms
and conditions contained herein.

          NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

          SECTION 6.  AMENDMENTS.  The Credit Agreement is hereby amended
(effective as provided in Section 3 hereof) as follows:

          A.  Section 9.11 of the Credit Agreement is amended by changing
     the references to "($10,000,000")", "$20,000,000" and "$50,000,000" at
     the end of the table in said Section 9.11 to read "($12,500,000"),
     "$5,000,000" and "$20,000,000", respectively.

          B.  Section 9.13 of the Credit Agreement is amended to read as
     follows:

               9.13  Fixed Charges Ratio.  The Company will not permit
          the Fixed Charges Ratio to be less than 1 to 1 on the last
          day of any fiscal quarter of the Company.

          C.  Each reference in the Credit Agreement and the other Credit
     Documents to the Credit Agreement shall be deemed to be a reference to
     the Credit Agreement as amended hereby.

Except as expressly provided in this Section 1, the Credit Agreement shall
remain unchanged and in full force and effect.

          SECTION 7.  REPRESENTATIONS AND WARRANTIES.  Each of the Company and
the Subsidiary Guarantor represents and warrants that:

          A.  The execution and delivery of this Amendment by it has been duly
authorized by all necessary corporate action on its part.

          B.  This Amendment has been duly executed and delivered by it, and
each of this Amendment and the Credit Agreement as modified hereby constitutes
its legal, valid and binding obligation enforceable in accordance with its
respective terms subject, however, to the application by a court of general
principles of equity and to the effect of any applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' rights
generally.

          SECTION 8.  EFFECTIVENESS.  The provisions of Section 1 hereof shall
become effective on the date on which counterparts hereof have been duly
executed by the Company, the Subsidiary Guarantor, the Banks and the
Administrative Agent and delivered to the Administrative Agent.

          SECTION 9.  COUNTERPARTS.  This Amendment may be executed in any
number of counterparts, each of which may be deemed an original but all of which
together shall constitute one and the same instrument.

          SECTION 10.  GOVERNING LAW.  This Amendment shall be governed and
construed in accordance with the laws of the State of New York.

          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed by their respective officers duly authorized as of the date first
above written.

RHEOX, INC.


By                            
  Name:
  Title:

RHEOX INTERNATIONAL, INC.


By______________________________
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION), as
   Co-Agent and

   Administrative Agent 


By_____________________________
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.,
  as Co-Agent


By_____________________________
  Name:
  Title:

THE CHASE MANHATTAN BANK
  (NATIONAL ASSOCIATION)


By_____________________________
  Name:
  Title:

THE NIPPON CREDIT BANK, LTD.


By_____________________________
  Name:
  Title:

VAN KAMPEN MERRITT PRIME
  RATE INCOME TRUST


By_____________________________
  Name:
  Title:

CHANCELLOR SENIOR SECURED
  MANAGEMENT, INC., as Investment
  Advisor to:

RESTRUCTURED OBLIGATIONS BACKED
  BY SENIOR ASSETS B.V.


By_____________________________
  Name:
  Title:

GIROCREDIT BANK,
  NEW YORK BRANCH


By_____________________________
  Name:
  Title:

BANQUE PARIBAS


By_____________________________
  Name:
  Title: