Document:

<PAGE>
EXHIBIT 10.6

                           NATIONAL QUALITY CARE, INC.
                       NONQUALIFIED STOCK OPTION AGREEMENT

         THIS NONQUALIFIED STOCK OPTION AGREEMENT ("Agreement") is made as of
December 18, 2001 by and between NATIONAL QUALITY CARE, INC., a Delaware
corporation (the "Company"), and Victor Gura M.D. ("Optionee").

                                  R E C I T A L
                                  -------------

         WHEREAS, the Company and the Optionee have entered into a certain
Technology Purchase Agreement and certain other related agreements, each of even
date herewith; and

         WHEREAS, in connection with the execution of the Technology Purchase
Agreement, the Board of Directors of the Company (the "Board of Directors") has
authorized the granting to Optionee of a non-qualified stock option to purchase
the number of shares of Common Stock of the Company specified in Paragraph 1
hereof, at the price specified therein, such option to be for the term and upon
the terms and conditions hereinafter stated.

                                A G R E E M E N T
                                -----------------

         NOW, THEREFORE, in consideration of the premises and of the
undertakings of the parties hereto contained herein, it is hereby agreed:

         1. NUMBER OF SHARES; OPTION PRICE. Pursuant to said action of the Board
of Directors, the Company hereby grants to Optionee, the option ("Option") to
purchase up to 5,000,000 shares ("Option Shares") of Common Stock of the
Company, at the exercise price of $1.25 per share.

         2. TERM. The Options shall expire five (5) years from the date of
vesting of the respective Options, as described in Section 3 below, but in no
event later than ten (10) years from the date first written above.

         3. SHARES SUBJECT TO EXERCISE. The Options shall be exercisable as
follows:

                  (a) 1,000,000 Options shall vest upon the filing and execution
         of the Technology Purchase Agreement and the exhibits thereto effecting
         the assignment to the Company of each of the patent applications
         relating to the Renal Replacement Patent and the Peritoneal Patent, as
         such terms are defined in the Technology Purchase Agreement.

                  (b) 1,000,000 Options shall vest upon the completion by the
         Company of the first prototype of the Wearable Continuous Renal
         Replacement Therapy Device.

<PAGE>

                  (c) 1,000,000 Options shall vest upon the successful
         completion by the Company of animal studies in connection with an
         application for marketing approval with respect to a product related to
         the Wearable Continuous Renal Replacement Therapy Device, such that the
         United States Food and Drug Administration ("USFDA") allows initial
         human trials with respect to such product to commence.

                  (d) 1,000,000 Options shall vest upon the successful
         completion by the Company of human studies on at least ten (10)
         patients in connection with an application for marketing approval with
         respect to a product related to the Wearable Continuous Renal
         Replacement Therapy Device.

                  (e) 1,000,000 Options shall vest upon the granting by USFDA of
         pre-marketing approval or full marketing approval for a product related
         to the Wearable Continuous Renal Replacement Therapy Device; PROVIDED,
         HOWEVER, in the event such approval shall be granted, and the Options,
         which may vest under Sections 3(c) or (d) shall not have otherwise
         vested, then the Options referenced in Section 3(c) or (d) shall vest
         simultaneously with the vesting of the Options in the initial clause of
         this Section 3(e).

         4. METHOD AND TIME OF EXERCISE. The Option may be exercised by written
notice delivered to the Company stating the number of shares with respect to
which the Option is being exercised, together with a check made payable to the
Company in the amount of the purchase price of such shares plus the amount of
applicable federal, state and local withholding taxes, and the written statement
provided for in Paragraph 8 hereof, if required by such Paragraph 8. No fewer
than 100 shares may be purchased at any one time unless the number purchased is
the total number purchasable under such Option at the time. Only whole shares
may be purchased.

         5. TAX WITHHOLDING. As a condition to exercise of this Option, the
Company may require the Optionee to pay over to the Company all applicable
federal, state and local taxes which the Company is required to withhold with
respect to the exercise of this Option. At the discretion of the Company and
upon the request of the Optionee, the minimum statutory withholding tax
requirements may be satisfied by the withholding of shares of Common Stock
otherwise issuable to the Optionee upon the exercise of this Option.

         6. NONTRANSFERABILITY. This Option may not be assigned or transferred
except, if applicable, by will or by the laws of descent and distribution, and
may be exercised only by Optionee during Optionee's lifetime and after
Optionee's death, by Optionee's representative or by the person entitled thereto
under Optionee's will or the laws of intestate succession; PROVIDED, HOWEVER,
that, Optionee, with the approval of the Board of Directors, may transfer this
Option, for no consideration, to or for the benefit of Optionee's Immediate
Family (including, without limitation, to a trust for the benefit of members of
Optionee's Immediate Family or to a partnership or limited liability company for
one or more members of Optionee's Immediate Family), subject to such limits as
the Board of Directors may establish, and the transferee shall remain subject to
all terms and conditions applicable to the Option prior to such transfer. The

                                       2
<PAGE>

foregoing right to transfer the Option shall apply to the right to consent to
amendments to this Agreement and, in the discretion of the Board of Directors,
shall also apply to the right to transfer ancillary rights associated with the
Option. The term "Immediate Family" shall mean Optionee's spouse, parents,
children, stepchildren, adoptive relationships, sisters, brothers and
grandchildren (and for this purpose, shall also include Optionee). In no event
shall any purported transfer be effective until such time that the Optionee
shall deliver to the Company a duly completed and signed written Assignment,
substantially in the form attached to this Option. The Company shall have no
obligation whatever to give notice to any transferee of any matter, including
without limitation early termination of any Option in accordance with the terms
and conditions of this Agreement.

         7. OPTIONEE NOT A SHAREHOLDER. Optionee shall have no rights as a
shareholder with respect to the Common Stock of the Company covered by the
Option until the date of issuance of a stock certificate or stock certificates
to him upon exercise of the Option. No adjustment will be made for dividends or
other rights for which the record date is prior to the date such stock
certificate or certificates are issued.

         8. RESTRICTIONS ON SALE OF SHARES. Optionee represents and agrees that,
upon Optionee's exercise of the Option in whole or part, unless there is in
effect at that time under the Securities Act of 1933 a registration statement
relating to the shares issued to him, he will acquire the shares issuable upon
exercise of this Option for the purpose of investment and not with a view to
their resale or further distribution, and that upon each exercise thereof
Optionee will furnish to the Company a written statement to such effect,
satisfactory to the Company in form and substance. Optionee agrees that any
certificates issued upon exercise of this Option may bear a legend indicating
that their transferability is restricted in accordance with applicable state or
federal securities law. Any person or persons entitled to exercise this Option
under the provisions of Paragraph 5 hereof shall, upon each exercise of the
Option under circumstances in which Optionee would be required to furnish such a
written statement, also furnish to the Company a written statement to the same
effect, satisfactory to the Company in form and substance, PROVIDED HOWEVER,
that the Company shall use its best efforts to cause the shares underlying the
Option to be registered at the earliest practicable time.

         9. NOTICES. All notices to the Company and the Optionee shall be
delivered in the manner set forth in the Technology Purchase Agreement.

         10. ADJUSTMENTS. If there is any change in the capitalization of the
Company affecting in any manner the number or kind of outstanding shares of
Common Stock of the Company, whether by stock dividend, stock split,
reclassification or recapitalization of such stock, or because the Company has
merged or consolidated with one or more other corporations (and provided the
Option does not thereby terminate pursuant to Section 2 hereof), then the number
and kind of shares then subject to the Option and the price to be paid therefor
shall be appropriately adjusted by the Board of Directors; PROVIDED, HOWEVER,
that in no event shall any such adjustment result in the Company's being
required to sell or issue any fractional shares. Any such adjustment shall be
made without change in the aggregate purchase price applicable to the
unexercised portion of the Option, but with an appropriate adjustment to the
price of each Share or other unit of security covered by this Option.

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<PAGE>

         11. CESSATION OF CORPORATE EXISTENCE. Notwithstanding any other
provision of this Option, upon the dissolution or liquidation of the Company,
the reorganization, merger or consolidation of the Company with one or more
corporations as a result of which the Company is not the surviving corporation,
or the sale of substantially all the assets of the Company or of more than 50%
of the then outstanding stock of the Company to another corporation or other
entity, the Option granted hereunder shall terminate; provided, however, that:
(i) each Option for which no option has been tendered by the surviving
corporation in accordance with all of the terms of provision (ii) immediately
below shall, within five days before the effective date of such dissolution or
liquidation, merger or consolidation or sale of assets in which the Company is
not the surviving corporation or sale of stock, become fully exercisable; or
(ii) in its sole and absolute discretion, the surviving corporation may, but
shall not be so obligated to, tender to any Optionee, an option to purchase
shares of the surviving corporation, and such new option or options shall
contain such terms and provisions as shall be required substantially to preserve
the rights and benefits of this Option.

         12. INVALID PROVISIONS. In the event that any provision of this
Agreement is found to be invalid or otherwise unenforceable under any applicable
law, such invalidity or unenforceability shall not be construed as rendering any
other provisions contained herein invalid or unenforceable, and all such other
provisions shall be given full force and effect to the same extent as though the
invalid or unenforceable provision were not contained herein.

         13. APPLICABLE LAW. This Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware.

         14. COUNTERPARTS. This Agreement may be executed in counterparts, all
of which shall be considered one and the same agreement, and shall become
effective when one or more counterparts have been signed by each of the parties
hereto and delivered to the other.

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<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date and year first above written.

                                              NATIONAL QUALITY CARE, INC.

                                              ("Company")

                                              By: /S/ RONALD LANG, M.D.
                                                  ------------------------------
                                                  Ronald P. Lang
                                                  Secretary

Social Security Number
or Employer Identification
Number:                                       ("Optionee")

-----------------------

                                              /S/ VICTOR GURA, M.D.
                                              ----------------------------------
                                              Victor Gura M.D.

                                              Address:

                                              ----------------------------------
                                              ----------------------------------
                                              ----------------------------------
                                              ----------------------------------

                                       5<PAGE>
EXHIBIT 10.7

                           NATIONAL QUALITY CARE, INC.
                       NONQUALIFIED STOCK OPTION AGREEMENT

         THIS NONQUALIFIED STOCK OPTION AGREEMENT ("Agreement") is made as of
December 18, 2001 by and between NATIONAL QUALITY CARE, INC., a Delaware
corporation (the "Company"), with its principal office located at 1835 South La
Cienega Boulevard, Suite 235, Los Angeles, California 90035 and Ronald P. Lang,
M.D. ("Optionee"), with his office located at is 240 La Cienega Blvd., Suite
300, Beverly Hills, California 90212.

                                  R E C I T A L
                                  -------------

         WHEREAS, the Company and Victor Gura, M.D. have entered into a certain
Technology Purchase Agreement and certain other related agreements, each of even
date herewith;

         WHEREAS, the Company desires to recognize the contributions of the
Optionee with respect to the development of the transferred technology
underlying the Technology Purchase Agreement; and

         WHEREAS, in connection with the execution of the Technology Purchase
Agreement, the Board of Directors of the Company (the "Board of Directors") has
authorized the granting to Optionee of a non-qualified stock option to purchase
the number of shares of Common Stock of the Company specified in Paragraph 1
hereof, at the price specified therein, such option to be for the term and upon
the terms and conditions hereinafter stated.

                                A G R E E M E N T
                                -----------------

         NOW, THEREFORE, in consideration of the premises and of the
undertakings of the parties hereto contained herein, it is hereby agreed:

         1. NUMBER OF SHARES; OPTION PRICE. Pursuant to said action of the Board
of Directors, the Company hereby grants to Optionee, the option ("Option") to
purchase up to 1,500,000 shares ("Option Shares") of Common Stock of the
Company, at the exercise price of $1.25 per share.

         2. TERM. The Options shall expire five (5) years from the date of
vesting of the respective Options, as described in Section 3 below, but in no
event later than ten (10) years from the date first written above.

         3. SHARES SUBJECT TO EXERCISE. The Options shall be exercisable as
follows:

                  (a) 300,000 Options shall vest upon the filing and execution
         of the Technology Purchase Agreement and the exhibits thereto effecting
         the assignment to the Company of each of the patent applications
         relating to the Renal Replacement Patent and the Peritoneal Patent, as
         such terms are defined in the Technology Purchase Agreement.

<PAGE>

                  (b) 300,000 Options shall vest upon the completion by the
         Company of the first prototype of the Wearable Continuous Renal
         Replacement Therapy Device.

                  (c) 300,000 Options shall vest upon the successful completion
         by the Company of animal studies in connection with an application for
         marketing approval with respect to a product related to the Wearable
         Continuous Renal Replacement Therapy Device, such that the United
         States Food and Drug Administration ("USFDA") allows initial human
         trials with respect to such product to commence.

                  (d) 300,000 Options shall vest upon the successful completion
         by the Company of human studies on at least ten (10) patients in
         connection with an application for marketing approval with respect to a
         product related to the Wearable Continuous Renal Replacement Therapy
         Device.

                  (e) 300,000 Options shall vest upon the granting by USFDA of
         pre-marketing approval or full marketing approval for a product related
         to the Wearable Continuous Renal Replacement Therapy Device; PROVIDED,
         HOWEVER, in the event such approval shall be granted, and the Options,
         which may vest under Sections 3(c) or (d) shall not have otherwise
         vested, then the Options referenced in Section 3(c) or (d) shall vest
         simultaneously with the vesting of the Options in the initial clause of
         this Section 3(e).

         4. METHOD AND TIME OF EXERCISE. The Option may be exercised by written
notice delivered to the Company stating the number of shares with respect to
which the Option is being exercised, together with a check made payable to the
Company in the amount of the purchase price of such shares plus the amount of
applicable federal, state and local withholding taxes, and the written statement
provided for in Paragraph 8 hereof, if required by such Paragraph 8. No fewer
than 100 shares may be purchased at any one time unless the number purchased is
the total number purchasable under such Option at the time. Only whole shares
may be purchased.

         5. TAX WITHHOLDING. As a condition to exercise of this Option, the
Company may require the Optionee to pay over to the Company all applicable
federal, state and local taxes which the Company is required to withhold with
respect to the exercise of this Option. At the discretion of the Company and
upon the request of the Optionee, the minimum statutory withholding tax
requirements may be satisfied by the withholding of shares of Common Stock
otherwise issuable to the Optionee upon the exercise of this Option.

         6. NONTRANSFERABILITY. This Option may not be assigned or transferred
except, if applicable, by will or by the laws of descent and distribution, and
may be exercised only by Optionee during Optionee's lifetime and after
Optionee's death, by Optionee's representative or by the person entitled thereto
under Optionee's will or the laws of intestate succession; PROVIDED, HOWEVER,
that, Optionee, with the approval of the Board of Directors, may transfer this
Option, for no consideration, to or for the benefit of Optionee's Immediate
Family (including, without limitation, to a trust for the benefit of members of
Optionee's Immediate Family or to a partnership or limited liability company for
one or more members of Optionee's Immediate Family), subject to such limits as

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<PAGE>

the Board of Directors may establish, and the transferee shall remain subject to
all terms and conditions applicable to the Option prior to such transfer. The
foregoing right to transfer the Option shall apply to the right to consent to
amendments to this Agreement and, in the discretion of the Board of Directors,
shall also apply to the right to transfer ancillary rights associated with the
Option. The term "Immediate Family" shall mean Optionee's spouse, parents,
children, stepchildren, adoptive relationships, sisters, brothers and
grandchildren (and for this purpose, shall also include Optionee). In no event
shall any purported transfer be effective until such time that the Optionee
shall deliver to the Company a duly completed and signed written Assignment,
substantially in the form attached to this Option. The Company shall have no
obligation whatever to give notice to any transferee of any matter, including
without limitation early termination of any Option in accordance with the terms
and conditions of this Agreement.

         7. OPTIONEE NOT A SHAREHOLDER. Optionee shall have no rights as a
shareholder with respect to the Common Stock of the Company covered by the
Option until the date of issuance of a stock certificate or stock certificates
to him upon exercise of the Option. No adjustment will be made for dividends or
other rights for which the record date is prior to the date such stock
certificate or certificates are issued.

         8. RESTRICTIONS ON SALE OF SHARES. Optionee represents and agrees that,
upon Optionee's exercise of the Option in whole or part, unless there is in
effect at that time under the Securities Act of 1933 a registration statement
relating to the shares issued to him, he will acquire the shares issuable upon
exercise of this Option for the purpose of investment and not with a view to
their resale or further distribution, and that upon each exercise thereof
Optionee will furnish to the Company a written statement to such effect,
satisfactory to the Company in form and substance. Optionee agrees that any
certificates issued upon exercise of this Option may bear a legend indicating
that their transferability is restricted in accordance with applicable state or
federal securities law. Any person or persons entitled to exercise this Option
under the provisions of Paragraph 5 hereof shall, upon each exercise of the
Option under circumstances in which Optionee would be required to furnish such a
written statement, also furnish to the Company a written statement to the same
effect, satisfactory to the Company in form and substance, PROVIDED HOWEVER,
that the Company shall use its best efforts to cause the shares underlying the
Option to be registered at the earliest practicable time.

         9. NOTICES. All notices, requests or other communications under this
Agreement shall be in writing, and shall be sent to the Parties at their mailing
addresses listed in the first page of this Agreement, and shall be deemed to
have been duly given on the date of service if sent by facsimile (provided a
hard copy is sent in one of the manners specified below), or on the day
following service if sent by overnight air courier service with next day
delivery with written confirmation of delivery, or five (5) days after mailing
if sent by first class, registered or certified mail, return receipt requested.
Each Party is required to notify the other Parties in the above manner of any
change of address.

         10. ADJUSTMENTS. If there is any change in the capitalization of the
Company affecting in any manner the number or kind of outstanding shares of
Common Stock of the Company, whether by stock dividend, stock split,
reclassification or recapitalization of such stock, or because the Company has
merged or consolidated with one or more other corporations (and provided the
Option does not thereby terminate pursuant to Section 2 hereof), then the number
and kind of shares then subject to the Option and the price to be paid therefor
shall be appropriately adjusted by the Board of Directors; PROVIDED, HOWEVER,
that in no event shall any such adjustment result in the Company's being
required to sell or issue any fractional shares. Any such adjustment shall be
made without change in the aggregate purchase price applicable to the
unexercised portion of the Option, but with an appropriate adjustment to the
price of each Share or other unit of security covered by this Option.

                                       3
<PAGE>

         11. CESSATION OF CORPORATE EXISTENCE. Notwithstanding any other
provision of this Option, upon the dissolution or liquidation of the Company,
the reorganization, merger or consolidation of the Company with one or more
corporations as a result of which the Company is not the surviving corporation,
or the sale of substantially all the assets of the Company or of more than 50%
of the then outstanding stock of the Company to another corporation or other
entity, the Option granted hereunder shall terminate; provided, however, that:
(i) each Option for which no option has been tendered by the surviving
corporation in accordance with all of the terms of provision (ii) immediately
below shall, within five days before the effective date of such dissolution or
liquidation, merger or consolidation or sale of assets in which the Company is
not the surviving corporation or sale of stock, become fully exercisable; or
(ii) in its sole and absolute discretion, the surviving corporation may, but
shall not be so obligated to, tender to any Optionee, an option to purchase
shares of the surviving corporation, and such new option or options shall
contain such terms and provisions as shall be required substantially to preserve
the rights and benefits of this Option.

         12. INVALID PROVISIONS. In the event that any provision of this
Agreement is found to be invalid or otherwise unenforceable under any applicable
law, such invalidity or unenforceability shall not be construed as rendering any
other provisions contained herein invalid or unenforceable, and all such other
provisions shall be given full force and effect to the same extent as though the
invalid or unenforceable provision were not contained herein.

         13. APPLICABLE LAW. This Agreement shall be governed by and construed
in accordance with the laws of the State of Delaware.

         14. COUNTERPARTS. This Agreement may be executed in counterparts, all
of which shall be considered one and the same agreement, and shall become
effective when one or more counterparts have been signed by each of the parties
hereto and delivered to the other.

                                       4
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date and year first above written.

                                           NATIONAL QUALITY CARE, INC.

                                           ("Company")

                                           By: /S/ VICTOR GURA, M.D.
                                               ---------------------------------
                                               Victor Gura M.D.
                                               Chief Executive Officer

Social Security Number
or Employer Identification
Number:                                    ("Optionee")

-----------------------

                                           /S/ RONALD LANG, M.D.
                                           -------------------------------------
                                           Ronald P. Lang

                                           Address:

                                           -------------------------------------
                                           -------------------------------------
                                           -------------------------------------
                                           -------------------------------------

                                       5

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