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                                                                    EXHIBIT 3.18

                                     BY-LAWS
                                       OF
                            CHARLES SPRINGFIELD, M.D.
                           A PROFESSIONAL CORPORATION,

                            A CALIFORNIA CORPORATION

                                    ARTICLE I

                                     OFFICES

         Section 1. PRINCIPAL OFFICE. The principal office for the transaction
of business of the corporation is hereby fixed and located at 5389 Sagebrush
Trail, Redding, CA 96003. The location may be changed by approval of a majority
of the authorized Directors, and additional offices may be established and
maintained at such other place or places, either within or without California,
as the Board of Directors may from, time to time designate.

         Section 2. OTHER OFFICES. Branch or subordinate offices may at any tine
be established by the Board of Directors at any place or places where the
corporation is qualified to do business.

                                   ARTICLE II
                             DIRECTORS - MANAGEMENT

         Section 1. RESPONSIBILITY OF BOARD OF DIRECTORS. Subject to the
provisions of the General Corporation Law and to any limitations in the Articles
of Incorporation of the corporation relating to action required to be approved
by the Shareholders, as that term is defined in Section 153 of the California
Code, or by the outstanding shares, as that term is defined in Section 152 of
the Code, the business and affairs of the corporation shall be managed and all
corporate powers shall be exercised by or under the direction of the Board of
Directors.

         Section 2. STANDARD OF CARE. Each Director shall perform the duties of
a Director, including the duties as a member of any committee of the Board upon
which the Director may serve, in good faith, in a manner such Director believes
to be in the best interests of the corporation, and with such care, including
reasonable inquiry, as an ordinary prudent person in a like position would use
under similar circumstances. (Sec. 309)

         Section 3. EXCEPTION FOR CLOSE CORPORATION. Notwithstanding the
provisions of Section 1, in the event that this corporation shall elect to
become a close corporation


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as defined in Sec. 186, its Shareholders may enter into a Shareholders'
Agreement as provided in Sec. 300(b). Said agreement may provide for the
exercise of corporate powers and the management of the business and affairs of
this corporation by the Shareholders, provided, however, such agreement shall,
to the extent and so long as the discretion or the powers of the Board in its
management of corporate affairs is controlled by such agreement, impose upon
each Shareholder who is a party thereof, liability for managerial acts performed
or omitted by such person pursuant thereto otherwise imposed upon Directors as
provided in Section 300(d).

         Section 4. NUMBER AND QUALIFICATION OF DIRECTORS. The authorized number
of Directors shall be one (1) until changed by a duly adopted amendment to the
Articles of Incorporation or by an amendment to this by-law adopted by the vote
or written consent of holders of a majority of the outstanding shares entitled
to vote, as provided in Sec. 212.

         Each Director shall be a licensed person as defined in Section 13401(c)
of the California Corporations Code.

         Section 5. ELECTION AND TERM OF OFFICE OF DIRECTORS. Directors shall be
elected at each annual meeting of the Shareholders to hold office until the next
annual meeting. Each Director, including a Director elected to fill a vacancy,
shall hold office until the expiration of the term for which elected and until a
successor has been elected and qualified.

         Section 6. VACANCIES. Vacancies in the Board of Directors may be filled
by a majority of the remaining Directors, though less than a quorum, or by a
sole remaining Director, except that a vacancy created by the removal of a
Director by the vote or written consent of the Shareholders or by court order
may be filled only by the vote of a majority of the shares entitled to vote
represented at a duly held meeting at which a quorum is present, or by the
written consent of holders of a majority of the outstanding shares entitled to
vote. Each Director so elected shall hold office until the next annual meeting
of the Shareholders and until a successor has been elected and qualified.

         A vacancy or vacancies in the Board of Directors shall be deemed to
exist in the event of the death, resignation, or removal of any Director, or if
the Board of Directors by resolution declares vacant the office of a Director
who has been declared of unsound mind by an order of court or convicted of a
felony, or if the authorized number of Directors is increased, or if the
shareholders fail, at any meeting of shareholders at which any Director or
Directors are elected, to elect the number of Directors to be voted for at that
meeting.


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         The Shareholders may elect a Director or Directors at any time to fill
any vacancy or vacancies not filled by the Directors, but any such election by
written consent shall require the consent of a majority of the outstanding
shares entitled to vote.

         Any Director may resign effective on giving written notice to the
Chairman of the Board, the President, the Secretary, or the Board of Directors,
unless the notice specifies a later time for that resignation to become
effective. If the resignation of a Director is effective at a future time, the
Board of Directors may elect a successor to take office when the resignation
becomes effective.

         No reduction of the authorized number of Directors shall have the
effect of removing any Director before that Director's term of office expires.

         Section 7. REMOVAL OF DIRECTORS. The entire Board of Directors or any
individual Director may be removed from office as provided by Secs. 302, 303 and
304 of the Corporations Code of the State of California. In such case, the
remaining Board members may elect a successor Director to fill such vacancy for
the remaining unexpired term of the Director so removed.

         Section 8. NOTICE, PLACE AND MANNER OF MEETINGS. Meetings of the Board
of Directors may be called by the Chairman of the Board, or the President, or
any Vice President, or any one (1) Director and shall be held at the principal
executive office of the corporation, unless some other place is designated in
the notice of the meeting. Members of the Board may participate in a meeting
through use of a conference telephone or similar communications equipment so
long as all members participating in such a meeting can hear one another.
Accurate minutes of any meeting of the Board or any committee thereof, shall be
maintained as required by Sec. 312 of the Code by the Secretary or other Officer
designated for that purpose.

         Section 9. ORGANIZATION MEETINGS. The organization meetings of the
Board of Directors shall be held immediately following the adjournment of the
annual meetings of the Shareholders.

         Section 10. OTHER REGULAR MEETINGS. Regular meetings of the Board of
Directors shall be held at the corporate offices, or such other place as may be
designated by the Board of Directors, as fellows:

         Time of Regular Meeting: 8:00 P.M.
         Date of Regular Meeting: March 1 of every year


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         If said day shall fall upon a holiday, such meetings shall be held on
the next succeeding business day thereafter. No notice need be given of such
regular meetings.

         Section 11. SPECIAL MEETINGS - NOTICES - WAIVERS. Special meetings of
the Board may be called at any time by the President or by one (1) Director if
only one is provided. At least forty-eight (48) hours notice of the time and
place of special meetings shall be delivered personally to the Directors or
personally communicated to them by a corporate Officer by telephone or
telegraph. If the notice is sent to a Director by letter, it shall be addressed
to him or her at his or her address as it is shown upon the records of the
corporation, or if it is not so shown on such records or is not readily
ascertainable, at the place in which the meetings of the Directors are regularly
held. In case such notice is mailed, it shall be deposited in the United States
mail, postage prepaid, in the place in which the principal executive office of
the corporation is located at least four (4) days prior to the time of the
holding of the meeting. Such mailing, telegraphing, telephoning or delivery as
above provided shall be due, legal and personal notice to such Director.

         When all of the Directors are present at any Directors' meeting,
however called or noticed, and either (i) sign a written consent thereto on the
records of such meeting, or, (ii) if a majority of the Directors are present and
if those not present sign a waiver of notice of such meeting or a consent to
holding the meeting or an approval of the minutes thereof, whether prior to or
after the holding of such meeting, which said waiver, consent or approval shall
be filed with the Secretary of the corporation, or, (iii) if a Director attends
a meeting without notice but without protesting, prior thereto or at its
commencement, the lack of notice, then the transactions thereof are as valid as
if had at a meeting regularly called and noticed.

         Section 12. SOLE DIRECTOR PROVIDED BY ARTICLES OF INCORPORATION OR
BY-LAWS. In the event only one (1) Director is required by the By-Laws or
Articles of Incorporation, then any reference herein to notices, waivers,
consents, meetings or other actions by a majority or quorum of the Directors
shall be deemed to refer to such notice, waiver, etc., by such sole Director,
who shall have all the rights and duties and shall be entitled to exercise all
of the powers and shall assume all the responsibilities otherwise herein
described as given to a Board of Directors.

         Section 13. DIRECTORS ACTIONS BY UNANIMOUS WRITTEN CONSENT. Any action
required or permitted to be taken by the Board of Directors may be taken without
a meeting and with the same force and effect as if taken by a unanimous vote of
Directors, if authorized by a


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writing signed individually or collectively by all members of the Board. Such
consent shall be filed with the regular minutes of the Board.

         Section 14. QUORUM. A majority of the number of Directors as fixed by
the Articles of Incorporation or By-Laws shall be necessary to constitute a
quorum for the transaction of business, and the action of a majority of the
Directors present at any meeting at which there is a quorum, when duly
assembled, is valid as a corporate act; provided that a minority of the
Directors, in the absence of a quorum, may adjourn from time to time, but may
not transact any business. A meeting at which a quorum is initially present may
continue to transact business, notwithstanding the withdrawal of Directors, if
any action taken is approved by a majority of the required quorum for such
meeting.

         Section 15. NOTICE OF ADJOURNMENT. Notice of the time and place of
holding an adjourned meeting need not be given to absent Directors if the time
and place be fixed at the meeting adjourned and held within twenty-four (24)
hours, but if adjourned more than twenty-four (24) hours, notice shall be given
to all Directors not present at the time of the adjournment.

         Section 16. COMPENSATION OF DIRECTORS. Directors, as such, shall not
receive any stated salary for their services, but by resolution of the Board a
fixed sum and expense of attendance, if any, may be allowed for attendance at
each regular and special meeting of the Board; provided that nothing herein
contained shall be construed to preclude any Director from serving the
corporation in any other capacity and receiving compensation therefor.

         Section 17. COMMITTEES. Committees of the Board may be appointed by
resolution passed by a majority of the whole Board. Committees shall be composed
of two (2) or more members of the Board, and shall have such powers of the Board
as may be expressly delegated to it by resolution of the Board of Directors,
except those powers expressly made nondelegable by Sec. 311.

         Section 18. ADVISORY DIRECTORS. The Board of Directors from time to
time may elect one or more persons to be Advisory Directors who shall not by
such appointment be members of the Board of Directors. Advisory Directors shall
be available from time to time to perform special assignments specified by the
President, to attend meetings of the Board of Directors upon invitation and to
furnish consultation to the Board. The period during which the title shall be
held may be prescribed by the Board of Directors. If no period is prescribed,
the title shall be held at the pleasure of the Board.


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         Section 19. RESIGNATIONS. Any Director may resign effective upon giving
written notice to the Chairman of the Board, the President, the Secretary or the
Board of Directors of the corporation, unless the notice specifies a later time
for the effectiveness of such resignation. If the resignation is effective at a
future time, a successor may be elected to take office when the resignation
becomes effective.

                                   ARTICLE III

                                    OFFICERS

         Section 1. OFFICERS. The Officers of the corporation shall be a
President, a Secretary and a Chief Financial Officer. The corporation may also
have, at the discretion of the Board of Directors, a Chairman of the Board, one
or more Vice Presidents, one or more Assistant Secretaries, one or more
Assistant Treasurers, and such other Officers as may be appointed in accordance
with the provisions of Section 3 of this Article III. Any number of offices may
be held by the same person. So long as the corporation has two (2) or more
Shareholders, each Officer shall be a licensed person, as defined in the
California Corporation Code Section 13401(c).

         Section 2. ELECTION. The Officers of the corporation, except such
Officers as may be appointed in accordance with the provisions of Section 3 or
Section 5 of this Article, shall be chosen annually by the Board of Directors,
and each shall hold office until he or she shall resign or shall be removed or
otherwise disqualified to serve, or a successor shall be elected and qualified.

         Section 3. SUBORDINATE OFFICERS, ETC. The Board of Directors may
appoint such other Officers as the business of the corporation may require, each
of whom shall hold office for such period, have such authority and perform such
duties as are provided in the By-Laws or as the Board of Directors may from time
to time determine.

         Section 4. REMOVAL AND RESIGNATION OF OFFICERS. Subject to the rights,
if any, of an Officer under any contract of employment, any Officer may be
removed, either with or without cause, by the Board of Directors, at any regular
or special meeting of the Board, or, except in case of an Officer chosen by the
Board of Directors, by any Officer upon whom such power of removal may be
conferred by the Board of Directors.

         Any Officer may resign at any time by giving written notice to the
corporation. Any resignation shall take effect at the date of the receipt of
that notice or at any later time specified in that notice; and, unless otherwise
specified in that notice, the acceptance of the resignation shall not be
necessary to make it effective. Any resignation is without prejudice to the
rights, if any, of the corporation under any contract to which the Officer is a
party.


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         Section 5. VACANCIES. A vacancy in any office because of death,
resignation, removal, disqualification or any other cause shall be filled in the
manner prescribed in the By-Laws for regular appointments to that office.

         Section 6. CHAIRMAN OF THE BOARD. The Chairman of the Board, if such an
officer be elected, shall, if present, preside at meetings of the Board of
Directors and exercise and perform such other powers and duties as may be from
time to time assigned by the Board of Directors or prescribed by the By-Laws. If
there is no President, the Chairman of the Board shall in addition be the Chief
Executive Officer of the corporation and shall have the powers and duties
prescribed in Section 7 of this Article III.

         Section 7. PRESIDENT. Subject to such supervisory powers, if any, as
may be given by the Board of Directors to the Chairman of the Board, if there be
such an Officer, the President shall be the Chief Executive Officer of the
corporation and shall, subject to the control of the Board of Directors, have
general supervision, direction and control of the business and Officers of the
corporation. He or she shall preside at all meetings of the Shareholders and in
the absence of the Chairman of the Board, or if there be none, at all meetings
of the Board of Directors. The President shall be ex officio a member of all the
standing committees, including the Executive Committee, if any, and shall have
the general powers and duties of management usually vested in the office of
President of a corporation, and shall have such other powers and duties as may
be prescribed by the Board of Directors or the By-Laws.

         Section 8. VICE PRESIDENT. In the absence or disability of the
President, the Vice Presidents, if any, in order of their rank as fixed by the
Board of Directors, or if not ranked, the Vice President designated by the Board
of Directors, shall perform all the duties of the President, and when so acting
shall have all the powers of, and be subject to, all the restrictions upon, the
President. The Vice Presidents shall have such other powers and perform such
other duties as from time to time may be prescribed for them respectively by the
Board of Directors or the By-Laws.

         Section 9. SECRETARY. The Secretary shall keep, or cause to be kept, a
book of minutes at the principal office or such other place as the Board of
Directors may order, of all meetings of Directors and Shareholders, with the
time and place of holding, whether regular or special, and if special, how
authorized, the notice thereof given, the names of those present at Directors'
meetings, the number of shares present or represented at Shareholders' meetings
and the proceedings thereof.


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         The Secretary shall keep, or cause to be kept, at the principal office
or at the Office of the corporation's transfer agent, a share register, or
duplicate share register, showing the names of the Shareholders and their
addresses; the number and classes of shares held by each; the number and date of
certificates issued for the same: and the number and date of cancellation of
every certificate surrendered for cancellation.

         The Secretary shall give, or cause to be given, notice of all the
meetings of the Shareholders and of the Board of Directors required by the
By-Laws or by law to be given. He or she shall keep the seal of the corporation
in safe custody and shall have such other powers and perform such other duties
as may be prescribed by the Board of Directors or by the By-Laws.

         Section 10. CHIEF FINANCIAL OFFICER. The Chief Financial Officer shall
keep and maintain, or cause to be kept and maintained in accordance with
generally accepted accounting Principles, adequate and correct accounts of the
properties and business transactions of the corporation, including accounts of
its assets, liabilities, receipts, disbursements, gains, losses, capital,
earnings (or surplus) and shares. The books of account shall at all reasonable
times be open to inspection by any Director. The Chief Financial Officer shall
be the Treasurer and as long as this corporation has one shareholder that
shareholder shall also be Treasurer of the corporation.

         This Officer shall deposit all moneys and other valuables in the name
and to the credit of the corporation with such depositaries as may be designated
by the Board of Directors. He or she shall disburse the funds of the corporation
as may be ordered by the Board of Directors, shall render to the President and
Directors, whenever they request it, an account of all of his or her
transactions and of the financial condition of the corporation, and shall have
such other powers and perform such other duties as may be prescribed by the
Board of Directors or the By-Laws.

                                   ARTICLE IV
                             SHAREHOLDERS' MEETINGS

         Section 1. PLACE OF MEETINGS. All meetings of the Shareholders shall be
held at the principal executive office of the corporation unless some other
appropriate and convenient location be designated for that purpose from time to
time by the Board of Directors.

         Section 2. ANNUAL MEETINGS. The annual meetings of the Shareholders
shall be held, each year, at the time and on the day following:

         Time of Meeting:  7:00 P.M.
         Date of Meeting:  March 1 of every year


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         If this day shall be a legal holiday, then the meeting shall be held on
the next succeeding business day, at the same hour. At the annual meeting, the
Shareholders shall elect a Board of Directors, consider reports of the affairs
of the corporation and transact such other business as may be property brought
before the meeting.

         Section 3. SPECIAL MEETINGS. Special meetings of the Shareholders may
be called at any time by the Board of Directors, the Chairman of the Board, the
President, a Vice President, the Secretary, or by one or more Shareholders
holding not less than one-tenth (1/10) of the voting power of the corporation.
Except as next provided, notice shall be given as for the annual meeting.

         Upon receipt of a written request addressed to the Chairman, President,
Vice President, or Secretary, mailed or delivered personally to such Officer by
any person (other than the Board) entitled to call a special meeting of
Shareholders, such Officer shall cause notice to be given, to the Shareholders
entitled to vote, that a meeting will be held at a time requested by the person
or persons calling the meeting, not less than thirty-five (35) nor more than
sixty (60) days after the receipt of such request. If such notice is not given
within twenty (20) days after receipt of such request, the persons calling the
meeting may give notice thereof in the manner provided by these By-Laws or apply
to the Superior Court as provided in Sec. 305(c).

         Section 4. NOTICE OF MEETINGS - REPORTS. Notice of meetings, annual or
special, shall be given in writing not less than ten (10) nor more than sixty
(60) days before the date of the meeting to Shareholders entitled to vote
thereat. Such notice shall be given by the Secretary or the Assistant Secretary,
or if there be no such Officer, or in the case of his or her neglect or refusal,
by any Director or Shareholder.

         Such notices or any reports shall be given personally or by mail or by
other means of written communication as provided in Sec. 601 of the Code and
shall be sent to the Shareholder's address appearing on the books of the
corporation, or supplied by him or her to the corporation for the purpose of
notice, and in the absence thereof, as provided in Sec. 601 of the Code.

         Notice of any meeting of Shareholders shall specify the place, the day
and the hour of meeting, and (1) in case of a special meeting, the general
nature of the business to be transacted and no other business may be transacted,
or (2) in the case of an annual meeting, those matters which the Board at date
of mailing, intends to present for action by the Shareholders. At any meetings
where Directors are to be elected, notice shall include the names of the
nominees, if any, intended at date of notice to be presented by management for
election.


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         If a Shareholder supplies no address, notice shall be deemed to have
been given if mailed to the place where the principal executive office of the
corporation, in California, is situated, or published at least once in some
newspaper of general circulation in the County of said principal office.

         Notice shall be deemed given at the time it is delivered personally or
deposited in the mail or sent by other means of written communication. The
Officer giving such notice or report shall prepare and file an affidavit or
declaration thereof.

         When a meeting is adjourned for forty-five (45) days or more, notice of
the adjourned meeting shall be given as in case of an original meeting. Save, as
aforesaid, it shall not be necessary to give any notice of adjournment or of the
business to be transacted at an adjourned meeting other than by announcement at
the meeting at which such adjournment is taken.

         Section 5. WAIVER OF NOTICE OR CONSENT BY ABSENT SHAREHOLDERS. The
transactions of any meeting of Shareholders, however called and noticed, shall
be valid as though had at a meeting duly held after regular call and notice, if
a quorum be present either in person or by proxy, and if, either before or after
the meeting, each of the Shareholders entitled to vote, not present in person or
by proxy, sign a written waiver of notice, or a consent to the holding of such
meeting or an approval of the minutes thereof. All such waivers, consents or
approvals shall be filed with the corporate records or made a part of the
minutes of the meeting. Attendance shall constitute a waiver of notice, unless
objection shall be made as provided in See. 601(e).

         Section 6. SHAREHOLDERS ACTING WITHOUT A MEETING - DIRECTORS. Any
action which may be taken at a meeting of the Shareholders, may be taken without
a meeting or notice of meeting if authorized by a writing signed by all of the
Shareholders entitled to vote at a meeting for such purpose, and filed with the
Secretary of the corporation, provided, further, that while ordinarily Directors
can only be elected by unanimous written consent under Sec. 603(d), if the
Directors fail to fill a vacancy, then a Director to fill that vacancy may be
elected by the written consent of persons holding a majority of shares entitled
to vote for the election of Directors.

         Section 7. OTHER ACTIONS WITHOUT A MEETING. Unless otherwise provided
in the GCL or the Articles, any action which may be taken at any annual or
special meeting of Shareholders may be taken without a meeting and without prior
notice, if a consent in writing, setting forth the action so taken, signed by
the holders of outstanding shares having not less than the


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minimum number of votes that would be necessary to authorize or take such action
at a meeting at which all shares entitled to vote thereon were present and
voted.

         Unless the consents of all Shareholders entitled to vote have been
solicited in writing,
                  (1) Notice of any Shareholder approval pursuant to Secs. 310,
                  317, 1201 or 2007 without a meeting by less than unanimous
                  written consent shall be given at least ten (10) days before
                  the consummation of the action authorized by such approval,
                  and (2) Prompt notice shall be given of the taking of any
                  other corporate action approved by Shareholders without a
                  meeting by less than unanimous written consent, to each of
                  those Shareholders entitled to vote who have not consented in
                  writing.

         Any Shareholder giving a written consent, or the Shareholder's
proxyholders, or a transferee of the shares of a personal representative of the
Shareholder or their respective proxyholders, may revoke the consent by a
writing received by the corporation prior to the time that written consents of
the number of shares required to authorize the proposed action have been filed
with the Secretary of the corporation, but may not do so thereafter. Such
revocation is effective upon its receipt by the Secretary of the corporation.

         Section 8. QUORUM. The holders of a majority of the shares entitled to
vote thereat, present in person, or represented by proxy, shall constitute a
quorum at all meetings of the Shareholders for the transaction of business
except as otherwise provided by law, by the Articles of Incorporation, or by
these By-Laws. If, however, such majority shall not be present or represented
at any meeting of the Shareholders, the Shareholders entitled to vote thereat,
present in person, or by proxy, shall have the power to adjourn the meeting from
time to time, until the requisite amount of voting shares shall be present. At
such adjourned meeting at which the requisite amount of voting shares shall be
represented, any business may be transacted which might have been transacted at
a meeting as originally notified.

         If a quorum be initially present, the Shareholders may continue to
transact business until adjournment, notwithstanding the withdrawal of enough
Shareholders to leave less than a quorum, if any action taken is approved by a
majority of the Shareholders required to initially constitute a quorum.

         Section 9. VOTING. Only persons in whose names shares entitled to vote
stand on the stock records of the corporation on the day of any meeting of
Shareholders, unless some other day


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be fixed by the Board of Directors for the determination of shareholders of
record, and then on such other day, shall be entitled to vote at such meeting.

         A "disqualified person" within the meaning of California Corporations
Code Section 13401(d) shall have no power to vote.

         Provided the candidate's name has been placed in nomination prior to
the voting and one or more Shareholder has given notice at the meeting prior to
the voting of the Shareholder's intent to cumulate the Shareholder's votes,
every Shareholder entitled to vote at any election for Directors of any
corporation for profit may cumulate their votes and give one candidate a number
of votes equal to the number of Directors to be elected multiplied by the number
of votes to which his or her shares are entitled, or distribute his or her votes
on the same principle among as many candidates as he or she thinks fit.

         The candidates receiving the highest number of votes up to the number
of Directors to be elected are elected.

         The Board of Directors may fix a time in the future not exceeding
thirty (30) days preceding the date of any meeting of Shareholders or the date
fixed for the payment of any dividend or distribution, or for the allotment of
rights, or when any change or conversion or exchange of shares shall go into
effect, as a record date for the determination of the Shareholders entitled to
notice of and to vote at any such meeting, or entitled to receive any such
dividend or distribution, or any allotment of rights, or to exercise the rights
in respect to any such change, conversion or exchange of shares. In such case
only Shareholders of record on the date so fixed shall be entitled to notice of
and to vote at such meeting, or to receive such dividends, distribution or
allotment of rights, or to exercise such rights, as the case may be
notwithstanding any transfer of any share on the books of the corporation after
any record date fixed as aforesaid. The Board of Directors may close the books
of the corporation against transfers of shares during the whole or any part of
such period.

         Section 10. PROXIES, VOTING TRUSTS, ETC. No Shareholder of a
professional corporation shall enter into a voting trust, proxy, or any other
arrangement vesting another person (other than another licensed person who is a
Shareholder of the same corporation) with the authority to exercise the voting
power of any or all of his or her shares, and any such purported voting trust,
proxy, or other arrangement shall be void.

         Section 11. ORGANIZATION. The President, or in the absence of the
President, any Vice President, shall call the meeting of the Shareholders to
order, and shall act as chairman of the


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meeting. In the absence of the President and all of the Vice Presidents,
Shareholders shall appoint a chairman for such meeting. The Secretary of the
corporation shall act as secretary of all meetings of the Shareholders, but in
the absence of the Secretary at any meeting of the Shareholders, the presiding
Officer may appoint any person to act as Secretary of the meeting.

         Section 12. INSPECTORS OF ELECTION. In advance of any meeting of
Shareholders the Board of Directors may, if they so elect, appoint inspectors of
election to act at such meeting or any adjournment thereof. If inspectors of
election be not so appointed, or if any persons so appointed fail to appear or
refuse to act, the chairman of any such meeting may, and on the request of any
Shareholder or his or her proxy shall, make such appointment at the meeting in
which case the number of inspectors shall be either one (1) or three (3) as
determined by a majority of the Shareholders represented at the meeting.

         Section 13. (A) SHAREHOLDERS' AGREEMENTS. Notwithstanding the above
provisions, in the event this corporation elects to become a close corporation,
an agreement between two (2) or more Shareholders thereof, if in writing and
signed by the parties thereof, may provide that in exercising any voting rights
the shares held by them shall be voted as provided therein or in Sec. 706, and
may otherwise modify these provisions as to Shareholders' meetings and actions.

                  (B) EFFECT OF SHAREHOLDERS' AGREEMENTS. Any Shareholders'
Agreement authorized by Sec. 300(b), shall only be effective to modify the terms
of these By-Laws if this corporation elects to become a close corporation with
appropriate filing of or amendment to its Articles as required by Sec. 202 and
shall terminate when this corporation ceases to be a close corporation. Such an
agreement cannot waive or alter Secs. 158, (defining close corporations), 202
(requirements of Articles of Incorporation), 500 and 501 relative to
distributions, 111 (merger), 1201(e) (reorganization) or Chapters 15 (Records
and Reports), 16 (Rights of Inspection), 18 (Involuntary Dissolution) or 22
(Crimes and Penalties). Any other provisions of the Code or these By-Laws may be
altered or waived thereby, but to the extent they are not so altered or waived,
these By-Laws shall be applicable.

                                    ARTICLE V
                       CERTIFICATES AND TRANSFER OF SHARES

         Section 1. CERTIFICATES FOR SHARES. Certificates for shares shall be-of
such form and device as the Board of Directors may designate and shall state the
name of the record holder of the shares represented thereby; its number; date of
issuance; the number of shares for



                                      -13-
   14
which it is issued; a statement of the rights, privileges, preferences and
restrictions, if any; a statement as to the redemption or conversion, if any; a
statement of liens or restrictions upon transfer or voting, if any; if the
shares be assessable or, if assessments are collectible by personal action, a
plain statement of such facts.

         All certificates shall be signed in the name of the corporation by the
Chairman of the Board or Vice Chairman of the Board or the President or Vice
President and by the Chief Financial Officer or an Assistant Treasurer or the
Secretary or any Assistant Secretary, certifying the number of shares and the
class or series of shares owned by the Shareholder.

         Any or all of the signatures on the certificate may be facsimile. In
case any Officer, transfer agent, or registrar who has signed or whose facsimile
signature has been placed on a certificate shall have ceased to be that Officer,
transfer agent, or registrar before that certificate is issued, it may be issued
by the Corporation with the same effect as if that person were an Officer,
transfer agent, or registrar at the date of issue.

         Section 2. TRANSFER ON THE BOOKS. Upon surrender to the Secretary or
transfer agent of the corporation of a certificate for shares duly endorsed or
accompanied by proper evidence of succession, assignment or authority to
transfer, it shall be the duty of the corporation to issue a new certificate to
the person entitled thereto, cancel the old certificate and record the
transaction upon its books.

         Section 3. LOST OR DESTROYED CERTIFICATES. Any person claiming a
certificate of stock to be lost or destroyed shall make an affidavit or
affirmation of that fact and shall, if the Directors so require, give the
corporation a bond of indemnity, in form and with one or more sureties
satisfactory to the Board, in at least double the value of the stock represented
by said certificate, whereupon a new certificate may be issued in the same tenor
and for the same number of shares as the one alleged to be lost or destroyed.

         Section 4. TRANSFER AGENTS AND REGISTRARS. The Board of Directors may
appoint one or more transfer agents or transfer clerks, and one or more
registrars, which shall be an incorporated bank or trust company, either
domestic or foreign, who shall be appointed at such times and places as the
requirements of the corporation may necessitate and the Board of Directors may
designate.

         Section 5. CLOSING STOCK TRANSFER BOOKS - RECORD DATE. In order that
the corporation may determine the Shareholders entitled to notice of any meeting
or to vote or entitled to receive payment of any dividend or other distribution
or allotment of any rights or


                                      -14-
   15
entitled to exercise any rights in respect of any other lawful action, the Board
may fix, in advance, a record date, which shall not be more than sixty (60) nor
less than ten (10) days prior to the date of such meeting nor more than sixty
(60) days prior to any other action.

         If no record date is fixed, the record date for determining
Shareholders entitled to notice of or to vote at a meeting of Shareholders shall
be at the close of business on the business day next preceding the day on which
notice is given, or, if notice is waived, at the close of business on the
business day next preceding the day on which the meeting is held. The record
date for determining Shareholders entitled to give consent to corporate action
in writing without a meeting, when no prior action by the Board is necessary,
shall be the day on which the first written consent is given.

         The record date for determining Shareholders for any other purpose
shall be at the close of business on the day on which the Board adopts the
resolution relating thereto, or the sixtieth (60th) day prior to the date of
such other action, whichever is later.

         Section 6. LEGEND CONDITION. The share certificates of this corporation
shall contain an appropriate legend setting forth the restrictions of Section 8
of this Article V. The person or persons issuing or transferring said shares
shall make sure said legend appears on the certificate and shall not be required
to transfer any shares free of such legend.

         Section 7. CLOSE CORPORATION CERTIFICATES. All certificates
representing shares of this corporation, in the event it shall. elect to become
a close corporation, shall contain the legend required by Sec. 418(c).

         Section 8. RESTRICTIONS ON OWNERSHIP AND TRANSFER OF SHARES. The shares
of a medical corporation may be owned only by a licensed person and may be
transferred only to a licensed person or to the issuing corporation.

         Where there are two (2) or more Shareholders in this corporation and
one of the Shareholders:

         (a) Dies;

         (b) Ceases to be an eligible Shareholder; or

         (c) Becomes a disqualified person as defined in Section 13401(d) of the
Corporations Code of the State of California for a period exceeding ninety (90)
days, his or her shares shall be sold and transferred to the corporation, its
Shareholders, or other eligible persons, on such terms as are agreed upon. Such
sale or transfer shall not be later than six (6) months after any such death and
not later than ninety (90) days after the date he or she ceases to be an
eligible Shareholder, or ninety (90) days after the date he or she becomes a
disqualified person.


                                      -15-
   16
         The share certificates of this corporation shall contain an appropriate
legend setting forth the foregoing restrictions.

         So long as the corporation has one (1) Shareholder, the foregoing
requirements of this section shall be set forth in the corporation's ByLaws. If
the corporation has two (2) or more Shareholders, the foregoing requirements of
this section shall be set forth in the corporation's ByLaws except that the
terms of the sale or transfer may be set forth in a written stock purchase
agreement entered into by and between this corporation and its Shareholders.

         A corporation and its Shareholders may, but need not, agree that shares
sold to it by a person who becomes a disqualified person may be resold to such
person if and when he or she again becomes an eligible Shareholder.

         The income of this corporation attributable to professional services
rendered while a Shareholder is a disqualified person shall not in any manner
accrue to the benefit of such Shareholder or his or her shares.

                                   ARTICLE VI
                         RECORDS - REPORTS - INSPECTION

         Section 1. RECORDS. The corporation shall maintain, in accordance with
generally accepted accounting principles, adequate and correct accounts, books
and records of its business and properties. All of such books, records and
accounts shall be kept at its principal executive office in the State of
California, as fixed by the Board of Directors from time to time.

         Section 2. INSPECTION OF BOOKS AND RECORDS. All books and records
provided for in Sec. 1500 shall be open to inspection of the Directors and
Shareholders from time to time and in the manner provided in said Sec. 1600 -
1602.

         Section 3. CERTIFICATION AND INSPECTION OF BY-LAWS. The original or a
copy of these By-Laws, as amended or otherwise altered to date, certified by the
Secretary, shall be kept at the corporation's principal executive office and
shall be open to inspection by the Shareholders of the corporation at all
reasonable times during office hours, as provided in Sec. 213 of the
Corporations Code.

         Section 4. CHECKS, DRAFTS, ETC. All checks, drafts, or other orders for
payment of money, notes or other evidences of indebtedness, issued in the name
of or payable to the corporation, shall be signed or endorsed by such person or
persons and in such manner as shall be determined from time to time by
resolution of the Board of Directors.


                                      -16-
   17
         Section 5. CONTRACTS, ETC. -- HOW EXECUTED. The Board of Directors,
except as in the By-Laws otherwise provided, may authorize any Officer or
Officers, agent or agents, to enter into any contract or execute any instrument
in the name of and on behalf of the corporation. Such authority may be general
or confined to specific instances. Unless so authorized by the Board of
Directors, no Officer, agent or employee shall have any power or authority to
bind the corporation by any contract or agreement, or to pledge its credit, or
to render it liable for any purpose or to any amount, except as provided in Sec.
313 of the Corporations Code.

                                   ARTICLE VII
                                 ANNUAL REPORTS

         Section 1. REPORT TO SHAREHOLDERS, DUE DATE. The Board of Directors
shall cause an annual report to be sent to the Shareholders not later than one
hundred twenty (120) days after the close of the fiscal or calendar year adopted
by the corporation. This report shall be sent at least fifteen (15) days before
the annual meeting of Shareholders to be held during the next fiscal year and in
the manner specified in Section 4 of Article IV of these ByLaws for giving
notice to Shareholders of the corporation. The annual report shall contain a
balance sheet as of the end of the fiscal year and an income statement and
statement of changes in financial position for the fiscal year, accompanied by
any report of independent accountants or, if there is no such report, the
certificate of an authorized Officer of the corporation that the statements were
prepared without audit from the books and records of the corporation.

         Section 2. WAIVER. The annual report to Shareholders referred to in
Section 1501 of the California General Corporation Law is expressly dispensed
with so long as this corporation shall have less than one hundred (100)
Shareholders. However, nothing herein shall be interpreted as prohibiting the
Board of Directors from issuing annual or other periodic reports to the
Shareholders of the corporation as they consider appropriate.

                                  ARTICLE VIII
                              AMENDMENTS TO BY-LAWS

         Section 1. AMENDMENT BY SHAREHOLDERS. New By-Laws may be adopted or
these By-Laws may be amended or repealed by the vote or written consent of
holders of a majority of the outstanding shares entitled to vote; provided,
however, that if the Articles of Incorporation of the corporation set forth the
number of authorized Directors of the corporation, the authorized number of
Directors may be changed only by an amendment of the Articles of Incorporation.


                                      -17-
   18
         Section 2. POWERS OF DIRECTORS. Subject to the right of the
Shareholders to adopt, amend, or repeal By-Laws, as provided in Section 1 of
this Article VIII, and the limitations of Sec. 204(a) (5) and Sec. 212, the
Board of Directors may adopt, amend or repeal any of these By-Laws other than a
By-Law or amendment thereof changing the authorized number of Directors.

         Section 3. RECORD OF AMENDMENTS. Whenever an amendment or new By-Law is
adopted, it shall be copied in the book of By-Laws with the original By-Laws, in
the appropriate place. If any By-Law is repealed, the fact of repeal with the
date of the meeting at which the repeal was enacted or written assent was filed
shall be stated in said book.

                                   ARTICLE IX
                                 CORPORATE SEAL

         The corporate seal shall be circular in form, and shall have inscribed
thereon the name of the corporation, the date of its incorporation, and the word
"California."

                                    ARTICLE X
                                  MISCELLANEOUS

         Section 1. REFERENCES TO CODE SECTIONS. "Sec." references herein refer
to the equivalent Sections of the General Corporation Law effective January 1,
1977, as amended.

         Section 2. REPRESENTATION OF SHARES IN OTHER CORPORATIONS. Shares of
other corporations standing in the name of this corporation may be voted or
represented and all incidents thereto may be exercised on behalf of the
corporation by the Chairman of the Board, the President or any Vice President
and the Secretary or an Assistant Secretary.

         Section 3. SUBSIDIARY CORPORATIONS. Shares of this corporation owned by
a subsidiary shall not be entitled to vote on any matter. A subsidiary for these
purposes is defined as a corporation, the shares of which possessing more than
25% of the total combined voting power of all classes of shares entitled to
vote, are owned directly or indirectly through one (1) or more subsidiaries.

         Section 4. INDEMNITY. The corporation may indemnify any Director,
Officer, agent or employee as to those liabilities and on those terms and
conditions as are specified in Sec. 317 of the Code. In any event, the
corporation shall have the right to purchase and maintain insurance on behalf of
any such persons whether or not the corporation would have the power to
indemnify such person against the liability insured against.

         Section 5. ACCOUNTING YEAR. The accounting year of the corporation
shall be fixed by resolution of the Board of Directors.


                                      -18-
   19
                       CERTIFICATE OF ADOPTION OF BY-LAWS

ADOPTION BY INCORPORATOR(S) OR FIRST DIRECTOR(S).

         The undersigned person(s) appointed in the Articles of Incorporation to
act as the Incorporator(s) or First Director(s) of the above named corporation
hereby adopt the same as the By-Laws of said corporation.

         Executed this 16 day of March, 1981.

                                             /s/ Charles Springfield
                                             _________________________
                                             CHARLES SPRINGFIELD, M.D.

CERTIFICATE BY SECRETARY.

         I DO HEREBY CERTIFY AS FOLLOWS:

         That I am the duly elected, qualified and acting Secretary of the above
named corporation, that the foregoing By-Laws were adopted as the By-Laws of
said corporation on the date set forth above by the person(s) appointed in the
Articles of Incorporation to act as the Incorporator(s) or First Director(s) of
said corporation.

         IN WITNESS WHEREOF, I have hereunto set my hand and affixed the
corporate seal this 16TH day of March, 1981

                                             /s/ Susan A. Springfield
                                             _____________________________
                                             Secretary


                                      -19-
   20
CERTIFICATE BY SECRETARY OF ADOPTION BY SHAREHOLDERS' VOTE.

         THIS IS TO CERTIFY:

         That I am the duly elected, qualified and acting Secretary of the above
named corporation and that the above and foregoing Code of By-Laws was submitted
to the Shareholders at their first meeting and recorded in the minutes thereof,
was ratified by the vote of Shareholders entitled to exercise the majority of
the voting power of said corporation.

         IN WITNESS WHEREOF, I have hereunto set my hand this 16 day of March,
1981.


                                             /s/ Susan Springfield
                                             _____________________________
                                             Secretary


                                      -20-
   21
                                    EXHIBIT A

                             AMENDMENT TO BYLAWS OF
           CHARLES LARRY SPRINGFIELD, M.D., A PROFESSIONAL CORPORATION

Article V, Section 6 and Article V, Section 8 of the Bylaws of this corporation
are hereby deleted in their entirety,

Except as provided herein, the Bylaws shall remain unchanged and in full force
and effect.

                                         (adopted 11/20/97 by shareholder)