Exhibit 10.6

                    REVISED AND RESTATED EMPLOYMENT CONTRACT
                    ----------------------------------------

     THIS REVISED AND RESTATED EMPLOYMENT CONTRACT (the "Contract") is made as
of November 1, 1996, between VIVRA INCORPORATED, a Delaware corporation
                             ------------------
("VIVRA") and KENT J. THIRY, an individual ("Thiry").
              -------------

     RECITALS:

     A. VIVRA has employed Thiry in an executive capacity pursuant to a Contract
dated as of December 1, 1992.

     B. VIVRA desires to revise the terms of Thiry's employment and restate his
contract, and Thiry desires to continue in VIVRA's employment.

     NOW, THEREFORE, Thiry and VIVRA agree:

     1. Definitions. As used in this Contract, the following terms have the
        -----------
following meanings:

     1.1 Beneficiary. "Beneficiary" means any Person or Persons designated from
         -----------
time to time by Thiry as beneficiary pursuant to paragraph 6.5.1.

     1.2 Board. "Board" means the Board of Directors of VIVRA.
         -----

     1.3 Change of Control. "Change of Control" means a change of control that
         -----------------
would be required to be reported pursuant to Item 6(e) of Schedule 14A of Rule
14 under the Exchange Act. Without limitation of the foregoing sentence, such a
change of control shall be deemed to have occurred if (i) any Person is or
becomes the beneficial owner (as defined in Rule 13d-3 of the Exchange Act),
directly or indirectly, of securities of VIVRA representing 30% or more of the
combined voting power of VIVRA's then outstanding securities, or (ii) during any
period of two (2) consecutive years during the term of this Contract,
individuals who at the beginning of such period constitute the Board cease for
any reason to constitute at least a majority thereof, unless the election of
each director who was not a director at the beginning of such period has been
approved in advance by directors representing at least two-thirds of the
directors then in office who were directors at the beginning of such period,
(iii) substantially all (80% or more) of Vivra's assets are sold or (iv) if
Vivra merges or consolidates with or into another entity where the stockholders
of Vivra immediately before such event own less than 50% of the surviving entity
immediately 

                                      -1-


<PAGE>

after such event. For purposes of this Agreement, a Change of Control does
not include a distribution to VIVRA's shareholders of stock of any subsidiary or
a purchase of securities or assets by a management-led purchasing group, which
includes Thiry.

     1.4 Code. "Code" means the Internal Revenue Code of 1986, as amended.
         ----

     1.5 Commission. "Commission" means the Securities and Exchange Commission.
         ----------

     1.6 Compete. "Compete" means either directly or indirectly to own,
         -------
initiate, manage, operate, join, control, advise, or participate in the
ownership, operation, management or control (other than as a shareholder owning
less than five percent (5%) of the capital stock of any entity, the shares of
which are traded on a national exchange) of any business in the U.S. similar to
the Existing or Other Businesses or to lease or sell real or personal property
to any such business.

     1.7 Confidential Information. "Confidential Information" means all company
         ------------------------
information which would constitute proprietary information or protectable trade
secrets under the laws of the State of California, including without limitation,
(i) market surveys, studies and analyses (ii) medical and personnel records,
(iii) statistical, financial, cost and accounting data, (iv) existing and
prospective patient and customer lists; and (v) other written materials
proprietary to VIVRA.

     1.8 Contingent Bonus. A bonus described in paragraph 3.1.3.
         ----------------

     1.9 Discretionary Bonus. A bonus described in paragraph 3.1.2.
         -------------------

     1.10 Employment Term. "Employment Term" means the period commencing
          ---------------
November 1, 1996 and continuing for the shorter of (i) a period of four (4)
years ending October 31, 2000, or (ii) a period ending on the date of any
termination pursuant to paragraph 5 or any wrongful termination by either VIVRA
or Thiry.

     1.11 Exchange Act. "Exchange Act" means the Securities Exchange Act of
          ------------
1934, as amended.

     1.12 Existing or Other Businesses. "Existing or Other Businesses" means
          ----------------------------
dialysis services, diabetes management, and any other business (a) in which
VIVRA is actively engaged during or at the end of the Employment Term and (b)
which, during the preceding twelve (12) months, represented at least ten percent
(10%) of Vivra's consolidated revenue.

                                      -2-

<PAGE>

     1.13 Fiscal Year. "Fiscal Year" means VIVRA's annual accounting period for
          -----------
financial accounting and reporting purposes, which currently is the period from
each December 1 to and including the next following November 30.

     1.14 GAAP. "GAAP" means generally accepted accounting principles in the
          ----
United States as in effect from time to time.

     1.15 Permanent Disability. "Permanent Disability" means any mental or
          --------------------
physical illness, disease or condition which results in Thiry's inability to
perform his duties during normal working hours for a period of not less than six
(6) consecutive months.

     1.16 Person. "Person" means any individual, corporation, partnership,
          ------
business trust, joint venture, association, joint stock company, trust,
unincorporated organization, government or agency, or political subdivision
thereof.

     1.17 Prior Contract. "Prior Contract" means the Employment Agreement
          --------------
between Thiry and VIVRA dated as of December 1, 1992.

     1.18 Salary. "Salary" means Thiry's annual base compensation of a minimum
          ------
of $275,000 per Fiscal Year, except when "Salary" is used in paragraphs 5.2.2,
5.2.3. and 5.2.4, in which contexts "Salary" means annual base compensation to
Thiry of a minimum of $300,000 per Fiscal Year.

     2. Employment and Duties.
        ---------------------

     2.1 Position. During the Employment Term, VIVRA shall employ Thiry and
         --------
Thiry shall serve VIVRA as its President and Chief Executive Officer.

     2.1.1 Directorship. Thiry is a Director of VIVRA for a term ending at the
           ------------
annual meeting of VIVRA's shareholders in 1998. VIVRA shall use its best efforts
to cause Thiry to be re-elected to the Board for further terms as long as he
serves as VIVRA's Chief Executive Officer. If he ceases to be employed by VIVRA
at any time Thiry agrees to offer to resign from the Board as of the date of his
termination of employment.

     2.2 Time and Effort. During the Employment Term, Thiry shall devote his
         ---------------
full productive business time, efforts, energies and abilities to VIVRA and
shall not render services to any other person or entity without the written
consent of the Board. Thiry, however, shall not be precluded from engaging in
civic, charitable or religious activities.

                                      -3-

<PAGE>

     2.3 Place of Business. During the Employment Term, Thiry's principal place
         -----------------
of business shall be in San Mateo County, California, and VIVRA shall not
require him to maintain his principal place of business elsewhere.

     3. Compensation, Reimbursement and Benefits.
        ----------------------------------------

     3.1 Compensation.
         ------------

     3.1.1 Salary. During the Employment Term, VIVRA shall pay the Salary to
           ------
Thiry, in equal monthly or more frequent installments, in accordance with
VIVRA's general practice and subject to legally required withholdings.

     3.1.2 Discretionary Bonuses. VIVRA may award Discretion-ary Bonuses to
           ---------------------
Thiry in the future as determined by the Board in its sole discretion, but VIVRA
shall be under no obligation, express or implied, to grant any future
Discretionary Bonuses.

     3.1.3 Contingent Bonus. If VIVRA's earnings per share are $1.25 or more for
           ----------------
the fiscal year ended November 30, 1996 and if he is employed as its Chief
Executive Officer throughout the period ending November 30, 1996, VIVRA shall
then pay Thiry a bonus of $300,000 which was granted and accrued in previous
years.

     3.2 Expense Reimbursement and Benefits.
         ----------------------------------

     3.2.1 Expense Reimbursement. During the Employment Term, VIVRA shall
           ---------------------
promptly reimburse Thiry, upon submission to VIVRA by Thiry of adequate
documentation, for all reasonable out-of-pocket expenses respecting
entertainment, travel, meals, hotel accommodations and other like-kind expenses,
in each case incurred by Thiry in the interest of VIVRA's business.

     3.2.2 Insurance. During the Employment Term, VIVRA shall provide life,
           ---------
medical, dental and hospital insurance to Thiry in the amount and on the terms
such insurance is provided from time to time to other executive officers of
VIVRA.

     3.2.3 Automobile Allowance. VIVRA shall provide Thiry with an automobile
           --------------------
allowance of Five Hundred Dollars ($500) per month, and shall reimburse him for
all reasonable parking and cellular phone expenses incurred in connection with
his duties hereunder.

     3.2.4 Vacation and Sick Leave. Thiry shall be entitled to paid vacation and
           -----------------------
sick leave each year of the same duration and under the same conditions as other
executive officers of VIVRA.

                                      -4-

<PAGE>

     3.2.5 YPO. During the Employment Term, VIVRA shall pay for, or promptly
           ---
reimburse Thiry for, all reasonable out of pocket expenses related to monthly
meetings and Chapter and Forum events of the Young Presidents Organization.

     3.3 Other Benefits. During the Employment Term, Thiry may participate in
         --------------
employment benefit plans and fringe benefit programs made available to other
executive officers of VIVRA subject to the generally applicable terms and
conditions of each such plan or program.

     3.4 Vesting on Change of Control. Whether or not Thiry terminates this
         ----------------------------
Contract pursuant to paragraph 5.1.2(b), all stock options and related stock
appreciation rights held by Thiry shall vest and become exercisable immediately
upon a Change of Control, and any plan or company restrictions on shares of
stock of VIVRA or on stock units that were awarded to Thiry under any plan or
arrangement maintained by VIVRA for the benefit of Thiry shall lapse upon the
occurrence of such an event.

     4. Protection of Business Information; Noncompetition; Nonsolicitation.
        -------------------------------------------------------------------

     4.1 Nondisclosure.
         -------------

     4.1.1 Confidential Information. In the operation, planning development and
           ------------------------
expansion of the Existing or Other Businesses, VIVRA has generated and will
generate Confidential Information which is and will be proprietary and
confidential and the disclosure of which would be extremely detrimental to VIVRA
and of great assistance to its competitors.

     4.1.2 Information Held as a Fiduciary. All of the Confidential Information
           -------------------------------
which is acquired by, communicated to or in any way comes into the possession or
control of Thiry shall be held by Thiry in a fiduciary capacity for the
exclusive benefit of VIVRA.

     4.1.3 Nondisclosure Covenant. During the employment term and for a period
           ----------------------
of two (2) years thereafter, Thiry shall not disclose any Confidential
Information to any person, without the consent of VIVRA.

     4.1.4 Exemptions. The restrictions set forth in this paragraph 4.1 shall
           ----------
not apply to any part of the Confidential Information which: (i) is or becomes
generally available to the public or publicly known other than as a result of
disclosure in breach of any obligation of confidentiality; (ii) becomes
available to Thiry on a nonconfidential basis from a source other than VIVRA or
its agents or affiliates; (iii) is disclosed 

                                      -5-

<PAGE>

pursuant to the requirement of a governmental agency or court of competent
jurisdiction or as otherwise required under applicable law; or (iv) was
otherwise known or available to Thiry without any obligation of confidentiality.

     4.1.5 Following Employment. Upon termination of this Agreement, Thiry shall
           --------------------
promptly relinquish and return to VIVRA all Confidential Information and all
files, correspondence, memoranda, diaries and other records, minutes, notes,
manuals, papers and other documents and data, however prepared or memorialized,
and all copies thereof, belonging to or relating to the business of VIVRA, that
are in Thiry's custody or control and that contain Confidential Information.

     4.2 Noncompetition Covenant. Except as provided in paragraphs 5.2.3 and
         -----------------------
5.2.4, during the Employment Term and for a period of two (2) years thereafter,
Thiry shall not Compete or plan or prepare to Compete with VIVRA.

     4.3 Nonsolicitation Covenant. Except as provided in paragraphs 5.2.3 and
         ------------------------
5.2.4, for a period of two (2) years after the Employment Term, Thiry shall not
solicit employees of VIVRA for employment.

     4.4 Scope and Duration; Severability. VIVRA and Thiry understand and agree
         --------------------------------
that the scope and duration of the covenants contained in this paragraph 4 are
reasonable both in time and area and are fairly necessary to protect the
business of VIVRA. Nevertheless, it is further agreed that such covenants shall
be regarded as divisible and shall be operative as to time and area to the
extent that they may be made so operative and, if any part of them is declared
invalid or unenforceable, the validity and enforceability of the remainder shall
not be affected.

     4.5 Injunction. Thiry understands and agrees that, due to the highly
         ----------
competitive nature of the health care industry, the breach of any of the
covenants set out in paragraphs 4.1.3, 4.1.5, 4.2 and 4.3 will cause irreparable
injury to VIVRA for which it will have no adequate monetary or other remedy at
law. Therefore, VIVRA shall be entitled, in addition to such other remedies as
it may have hereunder, to a temporary restraining order and to preliminary and
permanent injunctive relief for any breach or threatened breach of the covenants
without proof of actual damages that have been or may be caused hereby. In
addition, VIVRA shall have available all remedies provided under state and
federal statutes, rules and regulations as well as any and all other remedies as
may otherwise be contractually or equitably available.

                                      -6-

<PAGE>

     4.6 Assignment. Except as provided in paragraphs 5.2.3 and 5.2.4, Thiry
         ----------
agrees that the covenants contained in paragraph 4 shall inure to the benefit of
any successor or assign of VIVRA with the same force and effect as if such
covenants had been made by Thiry directly to such successor or assign.

     5. Termination. This Contrast may be terminated for any of the reasons set
        -----------
forth in paragraph 5.1, in each case with the consequences set out in paragraph
5.2.

     5.1 Grounds for Termination.
         -----------------------

     5.1.1 By VIVRA. This Contract may be terminated by VIVRA at any time, upon
           --------
thirty (30) days written notice to Thiry, for any of the following reasons;
provided, however, that VIVRA shall have the burden of proving the causes
described in subparagraphs (a) and (b) by clear and convincing evidence:

     (a) Breach or Neglect. Breach of any material provision of this Contract by
         -----------------
Thiry, which is not remedied within 30 days after written notice specifying such
breaches in reasonable detail, or breach or habitual neglect by Thiry of his
duties as director, officer or employee of VIVRA; or

     (b) Cause. For cause which shall consist of defalcation, fraud, breach of
         -----
trust, gross negligence, willful misconduct, chronic substance abuse which
interferes with essential functions of his duties, or conviction of a felony
involving moral turpitude, in each case in connection with performance of his
duties as director, officer or employee of VIVRA or which materially and
adversely affects VIVRA.

     5.1.2 By Thiry. This Contract may be terminated by Thiry at any time, upon
           --------
thirty (30) days written notice to VIVRA, for any of the following reasons:

     (a) Breach. Breach of any material provision of this Contract by VIVRA
         ------
which is not remedied within thirty (30) days after written notice specifying
such breach in reasonable detail; or

     (b) Change of Control. A Change of Control; provided, however, that
         -----------------
termination pursuant to this paragraph 5.1.2(b) shall be effective if and only
if Thiry gives VIVRA written notice of such termination within one (1) year
after a Change of Control.

     5.1.3 Permanent Disability. Either VIVRA or Thiry may terminate this
           --------------------
Contract upon thirty (30) days written notice upon Thiry's Permanent Disability.

                                      -7-

<PAGE>

     5.1.4 Death. This Contract shall terminate immediately upon the death of
           -----
Thiry.

     5.2 Effect of Termination. If this Contract is terminated pursuant to
         ---------------------
paragraph 5.1, the parties shall have the following rights and obligations:

     5.2.1 By VIVRA for Breach. If this Contract is terminated by VIVRA pursuant
           -------------------
to paragraph 5.1.1 or wrongfully terminated by Thiry, Thiry shall not have the
right or obligation to perform the services described in paragraph 2, he shall
resign as a Director of VIVRA and he shall not have any right to receive the
Salary or any other compensation, bonuses or benefits described in paragraph 3
after the date of termination, but Thiry shall be obligated to VIVRA as provided
in paragraph 4, and VIVRA shall have all remedies available at law or in equity.

     5.2.2 By VIVRA or Thiry upon Permanent Disability; Death. If this Contract
           --------------------------------------------------
is terminated by VIVRA or Thiry pursuant to paragraph 5.1.3 or if it terminates
pursuant to paragraph 5.1.4:

     (a) Permanent Disability. After his Permanent Disability, Thiry shall have
         --------------------
the obligations described in paragraph 4; and

     (b) Payments. Upon termination of this Contract pursuant to paragraph 5.1.3
         --------
or 5.1.4, VIVRA shall pay to Thiry or his Beneficiary, within seven (7) days
after the date of termination, (i) an amount equal to one (1) year's Salary plus
(ii) the Contingent Bonus whether or not, in this instance, the contingency
shall have occurred by the date of such termination.

     5.2.3 By Thiry for Breach. If this Contract is terminated by Thiry pursuant
           -------------------
to paragraph 5.1.2(a) or wrongfully terminated by VIVRA, he shall not have any
further obligation to VIVRA under paragraph 2 and under paragraph 4 (except as
to the Confidential Information provisions of paragraphs 4.1.2, 4.1.3, and
4.1.5) and VIVRA shall pay him within thirty (30) days after termination, an
amount equal to (i) one and one-half (1(OMEGA)) times the sum of his yearly
Salary plus the Discretionary Bonus actually paid to Thiry for the prior Fiscal
Year and (ii) the Contingent Bonus whether or not, in this instance, the
contin-gencies shall have occurred by the date of such termination. This
paragraph does not apply in the event of a Change of Control.

     5.2.4 Change of Control. If this Contract is terminated by Thiry pursuant
           -----------------
to paragraph 5.1.2(b) or is terminated by VIVRA or any successor entity within
one (1) year after a Change of Control and paragraph 5.1.1 does not apply, Thiry
shall not have any duty to mitigate his damage or any further obligation to
VIVRA under paragraphs 2 and under paragraph 4 (except as to 

                                      -8-

<PAGE>

the Confidential Information provisions of paragraphs 4.1.2, 4.1.3 and
4.1.5) and he shall be entitled to receive the follow- ing payments and benefits
from VIVRA or the successor entity:

     (a) Termination Payments. A cash payment to be made within thirty (30) days
         --------------------
after termination equal to the sum of: (i) 2.99 times the Salary plus any
Discretionary Bonus actually paid to Thiry for the Fiscal Year ended immediately
prior to the Change of Control termination and (ii) the Contingent Bonus whether
or not, in this instance, the contingencies shall have occurred by the date of
such termination.

     (b) Insurance Coverage. During the period commencing on the date of a
         ------------------
Change of Control termination and ending on the third anniversary thereof, Thiry
(and, where applicable, his dependents) shall be entitled to participate in any
insurance or similar plans maintained by VIVRA. Where applicable, Thiry's Salary
for purposes of such plans shall be deemed to be equal to the Salary he was
receiving at the time of the Change of Control termination. To the extent that
VIVRA finds it impractical to cover Thiry under its group insurance policies
during such three (3) year period, VIVRA shall provide him with the same level
of coverage under individual policies. The entire cost of insurance coverage
under this paragraph 5.2.4(b) shall be borne by VIVRA.

     (c) Outplacement Services. VIVRA shall provide Thiry with the use of a
         ---------------------
furnished office, secretary and telephone and access to facsimile and
photocopying machines for a one (1) year period following the Change of Control
termination. The cost of these services and facilities shall be borne entirely
by VIVRA.

     5.2.5 Payment and Computation of Salary upon Termination. Upon any
           --------------------------------------------------
termination of this Contract pursuant to paragraph 5.1:

     (a) Salary to Date of Termination. VIVRA shall pay Thiry the Salary to the
         -----------------------------
date of termination, and

     (b) Computation. As to terminations pursuant to subparagraphs 5.1.1, the
         -----------
Salary shall be that in effect on the day before the date of termination. As to
all other terminations, the Salary shall be that in effect on the day before the
date of termination calculated with a minimum annual base compensation of
$300,000.

     5.3 Withholding. Anything in this Contract to the contrary notwithstanding,
         -----------
all payments required to be made to Thiry or the Beneficiary under this Contract
shall be subject to the withholding of such amounts, if any, for income and
other payroll taxes and deductions as VIVRA may reasonably determine 

                                      -9-

<PAGE>

should be withheld pursuant to any applicable law or regulation.

     5.4 Examples. The following are examples of the payments to be made to
         --------
Thiry pursuant to paragraph 5.2 based on the assumptions that (i) Thiry's
employment terminates on April 30, 1997 and (ii) the Salary is $275,000 for
Fiscal Year 1997 and (iii) Thiry has received a Discretionary Bonus of $200,000
for Fiscal Year 1996. Under the foregoing assumptions, if:

     5.4.1 Paragraph 5.1.1. VIVRA terminates this Contract pursuant to paragraph
           ---------------
5.1.1, Thiry shall be paid only through April 30, 1997 at the Salary rate of
$275,000 per year (plus an amount equal to the Contingent Bonus but only if the
Contingent Bonus has been earned but not yet paid).

     5.4.2 Permanent Disability; Death. Thiry dies or if this Contract is
           ---------------------------
terminated pursuant to paragraph 5.1.3, VIVRA shall pay Thiry or his beneficiary
one (1) year's Salary at the rate of $300,000 plus an amount equal to the
Contingent Bonus ($300,000) (if the Contingent Bonus has been earned but not yet
paid), a total of either $300,000 or $600,000.

     5.4.3 Paragraph 5.1.2(a). Thiry terminates this Contract pursuant to
           ------------------
paragraph 5.1.2(a), VIVRA shall pay Thiry (i) one and one-half (1(OMEGA)) times
the sum of the Salary plus the Discretionary Bonus given to him for Fiscal Year
1996 (1.5 x ($300,000 + $200,000)) which totals $750,000, and (ii) the
Contingent Bonus ($300,000) (if the Contingent Bonus has been earned but not yet
paid), all of which would total $1,050,000.

     5.4.4 Paragraph 5.1.2(b). Thiry terminates this Contract pursuant to
           ------------------
paragraph 5.1.2(b), VIVRA or the successor entity shall pay Thiry (i) 2.99 times
the sum of the Salary plus the Discretionary Bonus given to him for Fiscal Year
1996 (2.99 x ($300,000 + $200,000)) which totals $1,495,000, and (ii) the
Contingent Bonus ($300,000) (if the Contingent Bonus has been earned but not yet
paid), all of which would total $1,795,000.

     6. Miscellaneous.
        -------------

     6.1 Prior Contracts Null and Void. VIVRA and Thiry agree that upon
         -----------------------------
execution and delivery of this Contract by each of them, the Prior Contract
shall terminate and be deemed null and void, and shall have no further force or
effect.

     6.2 Assignment by VIVRA. This Contract shall be binding upon and shall
         -------------------
inure to the benefit of any successors or assigns of VIVRA. As used in this
Contract, the term "successor" includes any Person or combination of Persons
acting in concert which at any time in any form or manner acquires all or

                                      -10-

<PAGE>

substantially all of the assets or business or more than thirty percent (30%) of
the voting stock of VIVRA.

     6.3 Nonassignability by Thiry. Neither Thiry nor any Beneficiary shall
         -------------------------
assign, transfer, pledge or hypothecate any rights, interests or benefits
created hereunder or hereby. Any attempt to do so contrary to the provisions of
this Contract, and any levy of any attachment, execution or similar process
created thereby, shall be null and void and without effect.

     6.4 Spendthrift Provision. Prior to actual receipt by Thiry or the
         ---------------------
Beneficiary, as the case may be, no right or benefit under this Contract and,
without limitation, no interest in any payment hereunder shall be:

     6.4.1 Anticipation. Anticipated, assigned or encumbered or subject to any
           ------------
creditor's claim or subject to execution, attachment or similar legal process,
or

     6.4.2 Liability for Debts: Claims. Applied on behalf of or subject to the
           ---------------------------
debts, contracts, liabilities or torts of the Person entitled or who might
become entitled to such benefits, or subject to the claims of any creditor of
any such Person.

     6.5 Beneficiary; Recipients of Payments; Designation of Beneficiary. The
         ---------------------------------------------------------------
Salary and other compensation and benefits payable by VIVRA pursuant to this
Contract shall be made only to Thiry during his lifetime or, in the event of his
death, to the Thiry-O'Leary Living Trust ("Beneficiary").

     6.5.1 Designation of Beneficiary. Thiry may from time to time change the
           --------------------------
Beneficiary by filing a new designation in writing with VIVRA's Corporate
Secretary. If no designation is in effect, any sums payable under this Contract
shall be paid to Thiry's estate.

     6.5.2 Elections. Whenever this Contract provides for any option or election
           ---------
by Thiry or the Beneficiary, the option shall be exercised or the election made
solely by the person or persons receiving payments pursuant to this Contract at
that time, and shall be made in that Person's sole discretion and without regard
to the effect of the decision on subsequent recipients of payments. Such
decision by such Person shall be final and binding on all subsequent recipients
of payments.

     6.6 Limitation on Payments. In the event that it is determined by counsel
         ----------------------
(or any other tax advisor) approved by Thiry and VIVRA that any compensation
payable hereunder, alone or when aggregated with other compensation payable to
Thiry, would constitute an "excess parachute payment" within the meaning of
Section 280G of the Internal Revenue Code of 1986, as 

                                      -11-

<PAGE>

amended, and the net, after-tax amount that Thiry would realize from the
compensation hereunder and from all other sources, considering Thiry's federal
and state income tax brackets and the effect of any nondeductible excise tax,
would be greater if the compensation payable hereunder were reduced, then the
compensation payable hereunder shall be reduced until Thiry's after-tax
compensation (taking into account state and federal income taxes, excise taxes
and all other applicable taxes) is maximized.

     6.7 Arbitration. If any controversy, question or dispute arises out of or
         -----------
relating to the construction, application or enforcement of this Contract, it
shall be settled by arbitration as follows:

     6.7.1 Appointment of Arbitrators. Within fifteen (15) days after the
           --------------------------
delivery of written notice of any such dispute from one to the other, VIVRA and
Thiry shall each appoint one person to hear and determine the dispute, and, if
the two (2) persons so selected are unable to agree on its resolution within ten
(10) days after their appointment, they shall select a third impartial
arbitrator, and the three arbitrators so selected shall hear and determine the
dispute within sixty (60) days thereafter.

     6.7.2 Finality. The determination of a majority of the arbitrators shall be
           --------
final and conclusive on Thiry and VIVRA.

     6.7.3 Rules. The arbitration shall be conducted in accordance with the
           -----
rules of the American Arbitration Association, and judgment on any award
rendered by the arbitrators may be entered in any court having jurisdiction.

     6.7.4 Discovery. The parties shall be entitled to avail themselves of all
           ---------
discovery procedures available in civil actions in the State of California, and,
without limitation, Thiry and VIVRA hereby incorporate section 1283.05 of the
California Code of Civil Procedure into this Contract pursuant to section 1283.1
of that Code.

     6.8 Notices. Any notice provided for by this Contract and any other notice,
         -------
demand or communication which either party may wish to send to the other (the
"Notices") shall be in writing and shall be deemed to have been properly given
if served by (a) personal delivery, or (b) registered or certified mail, return
receipt requested, in a sealed envelope, postage prepaid, addressed to the party
for which such notice is intended as follows:

                                      -12-

<PAGE>

            If to VIVRA:            VIVRA Incorporated
                                    Board of Directors
                                    400 Primrose, Suite 200
                                    Burlingame, CA 94010

            If to Thiry:            Kent J. Thiry
                                    124 Warren Avenue
                                    San Mateo, CA 94401

     6.8.1 Change of Address. Any address or name specified in this paragraph
           -----------------
6.8 may be changed by a Notice given by one party to the other party in
accordance with paragraph 6.8.

     6.8.2 Effective Date of Notice. All notices shall be given and effective as
           ------------------------
of the date of Personal delivery thereof or the date of receipt set forth on the
return receipt. The inability to deliver because of a changed address of which
no Notice was given, or rejection or other refusal to accept any Notice shall be
deemed to be the receipt of the Notice as of the date of Such inability to
deliver or rejection or refusal to accept.

     6.9 Governing Law: Jurisdiction. This Contract shall be construed in
         ---------------------------
accordance with and governed by the laws of the State of California. VIVRA
hereby consents and submits to the jurisdiction of the state and federal courts
in California in any suit for the enforcement or construction of or otherwise
arising out of this Contract.

                                      -13-

<PAGE>

     6.10 Counterparts. This Contract may be executed in any number of
          ------------
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

     IN WITNESS WHEREOF, this Contract has been executed and delivered by the
parties on the date set forth opposite their names.

     Dated: December 15, 1996

                                                /s/ Kent J. Thiry
                                        ----------------------------------
                                                  Kent J. Thiry


     Dated: December 11, 1996

                                        VIVRA INCORPORATED



                                        By      /s/ LeAnne M. Zumwalt
                                           -------------------------------
                                                  LeAnne M. Zumwalt

                                        Its    Chief Financial Officer
                                           -------------------------------