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                                                                     Exhibit 3.1

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                              AMENDED AND RESTATED

                                     BY-LAWS

                                       OF

                         CONCENTRA OPERATING CORPORATION

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                       Incorporated under the Laws of the

                                 State of Nevada

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                                  Adopted as of
                                September 8, 1999

                  As further Amended and Restated June 20, 2002

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                              AMENDED AND RESTATED

                                     BY-LAWS

                                       OF

                         CONCENTRA OPERATING CORPORATION

                             (a Nevada corporation)

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                                    ARTICLE I
                                     OFFICES

         The registered office of the Corporation in the State of Nevada shall
be located in the City of Reno, Nevada. The Corporation may establish or
discontinue, from time to time, such other offices within or without the State
of Nevada as may be deemed proper for the conduct of the Corporation's business.

                                   ARTICLE II
                            MEETINGS OF STOCKHOLDERS

         Section 1. Place of Meetings. All meetings of stockholders shall be
held at such place or places, within or without the State of Nevada, as may from
time to time be fixed by the Board of Directors, or as shall be specified in the
respective notices, or waivers of notice, thereof.

         Section 2. Annual Meeting. The annual meeting of stockholders for the
election of Directors and the transaction of other business shall be held on
such date and at such place as may be designated by the Board of Directors. At
each annual meeting the stockholders entitled to vote shall elect a Board of
Directors and may transact such other proper business as may come before the
meeting.

         Section 3. Special Meetings. A special meeting of the stockholders, or
of any class thereof entitled to vote, for any purpose or purposes, may be
called at any time by the Chairman of the Board, if any, or the President or by
order of the Board of Directors and shall be called by the Secretary upon the
written request of stockholders holding of record at least 50% of the
outstanding shares of stock of the Corporation entitled to vote at such meeting.
Such written request shall state the purpose or purposes for which such meeting
is to be called.

         Section 4. Notice of Meetings. Except as otherwise provided by law,
written notice of each meeting of stockholders, whether annual or special,
stating the place, date and hour of the meeting shall be given not less than ten
days or more than sixty days before the date on which the meeting is to be held
to each stockholder of record entitled to vote thereat by delivering a

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notice thereof to him personally or by mailing such notice in a postage prepaid
envelope directed to him at his address as it appears on the records of the
Corporation, unless he shall have filed with the Secretary of the Corporation a
written request that notices intended for him be directed to another address, in
which case such notice shall be directed to him at the address designated in
such request. Notice shall not be required to be given to any stockholder who
shall waive such notice in writing, whether prior to or after such meeting, or
who shall attend such meeting in person or by proxy unless such attendance is
for the express purpose of objecting, at the beginning of such meeting, to the
transactions of any business because the meeting is not lawfully called or
convened. Every notice of a special meeting of the stockholders, besides the
time and place of the meeting, shall state briefly the objects or purposes
thereof.

         Section 5. List of Stockholders. It shall be the duty of the Secretary
or other officer of the Corporation who shall have charge of the stock ledger to
prepare and make, at least ten days before every meeting of the stockholders, a
complete list of the stockholders entitled to vote thereat, arranged in
alphabetical order, and showing the address of each stockholder and the number
of shares registered in his name. Such list shall be open to the examination of
any stockholder, for any purpose germane to the meeting, during ordinary
business hours, for a period of at least ten days prior to the meeting, either
at a place within the city where the meeting is to be held, which place shall be
specified in the notice of the meeting, or, if not so specified, at the place
where the meeting is to be held. The list shall be kept and produced at the time
and place of the meeting during the whole time thereof and subject to the
inspection of any stockholder who may be present. The original or duplicate
ledger shall be the only evidence as to who are the stockholders entitled to
examine such list or the books of the Corporation or to vote in person or by
proxy at such meeting.

         Section 6. Quorum. At each meeting of the stockholders, the holders of
record of a majority of the issued and outstanding stock of the Corporation
entitled to vote at such meeting, present in person or by proxy, shall
constitute a quorum for the transaction of business, except where otherwise
provided by law, the Certificate of Incorporation or these By-laws. In the
absence of a quorum, any officer entitled to preside at, or act as Secretary of,
such meeting shall have the power to adjourn the meeting from time to time until
a quorum shall be constituted.

         Section 7. Voting. Every stockholder of record who is entitled to vote
shall at every meeting of the stockholders be entitled to one vote for each
share of stock held by him on the record date; except, however, that shares of
its own stock belonging to the Corporation or to another corporation, if a
majority of the shares entitled to vote in the election of directors of such
other corporation is held by the Corporation, shall neither be entitled to vote
nor counted for quorum purposes. Nothing in this Section shall be construed as
limiting the right of the Corporation to vote its own stock held by it in a
fiduciary capacity. At all meetings of the stockholders, a quorum being present,
all matters shall be decided by majority vote of the shares of stock entitled to
vote held by stockholders present in person or by proxy, except as otherwise
required by law or the Certificate of Incorporation. Unless demanded by a
stockholder of the Corporation present in person or by proxy at any meeting of
the stockholders and entitled to vote thereat or so directed by the chairman of
the meeting or required by law, the vote thereat on any question need not be by
written ballot. On a vote by written ballot, each ballot shall be signed by

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the stockholder voting, or in his name by his proxy, if there be such proxy, and
shall state the number of shares voted by him and the number of votes to which
each share is entitled.

         Section 8. Proxies. Each stockholder entitled to vote at a meeting of
stockholders or to express consent to corporate action in writing without a
meeting may authorize another person or persons to act for him by proxy. A proxy
acting for any stockholder shall be duly appointed by an instrument in writing
subscribed by such stockholder. No proxy shall be valid after the expiration of
three years from the date thereof unless the proxy provides for a longer period.

         Section 9. Action Without a Meeting. Any action required to be taken at
any annual or special meeting of stockholders or any action which may be taken
at any annual or special meeting of stockholders may be taken without a meeting,
without prior notice and without a vote, if a consent in writing setting forth
the action so taken shall be signed by the holders of outstanding stock having
not less than the 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. Prompt notice of the taking of the corporate action
without a meeting by less than unanimous written consent shall be given to those
stockholders who have not consented in writing.

                                   ARTICLE III
                               BOARD OF DIRECTORS

         Section 1. Powers.  The business and affairs of the Corporation shall
be managed  under the direction of the Board of Directors.

         Section 2. Election and Term. Except as otherwise provided by law,
Directors shall be elected at the annual meeting of stockholders and shall hold
office until the next annual meeting of stockholders and until their successors
are elected and qualify, or until they sooner die, resign or are removed. At
each annual meeting of stockholders, at which a quorum is present, the persons
receiving a plurality of the votes cast shall be the Directors. Acceptance of
the office of Director may be expressed orally or in writing, and attendance at
the organization meeting shall constitute such acceptance.

         Section 3. Number. The number of Directors shall be such number as
shall be determined from time to time by the Board of Directors and initially
shall be three.

         Section 4. Quorum and Manner of Acting. Unless otherwise provided by
law, the presence of 50% of the whole Board of Directors shall be necessary to
constitute a quorum for the transaction of business. In the absence of a quorum,
a majority of the Directors present may adjourn the meeting from time to time
until a quorum shall be present. Notice of any adjourned meeting need not be
given. At all meetings of Directors, a quorum being present, all matters shall
be decided by the affirmative vote of a majority of the Directors present,
except as otherwise required by law. The Board of Directors may hold its
meetings at such place or places within or without the State of Nevada as the
Board of Directors may from time to time determine or as shall be specified in
the respective notices, or waivers of notice, thereof.

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         Section 5.  Organization Meeting. Immediately after each annual meeting
of stockholders for the election of Directors the Board of Directors shall meet
at the place of the annual meeting of stockholders for the purpose of
organization, the election of officers and the transaction of other business.
Notice of such meeting need not be given. If such meeting is held at any other
time or place, notice thereof must be given as hereinafter provided for special
meetings of the Board of Directors, subject to the execution of a waiver of the
notice thereof signed by, or the attendance at such meeting of, all Directors
who may not have received such notice.

         Section 6.  Regular Meetings. Regular meetings of the Board of
Directors may be held at such place, within or without the State of Nevada, as
shall from time to time be determined by the Board of Directors. After there has
been such determination, and notice thereof has been once given to each member
of the Board of Directors as hereinafter provided for special meetings, regular
meetings may be held without further notice being given.

         Section 7.  Special Meetings; Notice. Special meetings of the Board of
Directors shall be held whenever called by the Chairman of the Board, if any,
the President or by a majority of the Directors. Notice of each such meeting
shall be mailed to each Director, addressed to him at his residence or usual
place of business, at least five days before the date on which the meeting is to
be held, or shall be sent to him at such place by telex or facsimile, or be
delivered personally or by telephone, not later than the day before the day on
which such meeting is to be held. Each such notice shall state the time and
place of the meeting and, as may be required, the purposes thereof. Notice of
any meeting of the Board of Directors need not be given to any Director if he
shall sign a written waiver thereof either before or after the time stated
therein for such meeting, or if he shall be present at the meeting. Unless
limited by law, the Certificate of Incorporation, these By-laws or the terms of
the notice thereof, any and all business may be transacted at any meeting
without the notice thereof having specifically identified the matters to be
acted upon.

         Section 8.  Removal of Directors. Any Director or the entire Board of
Directors may be removed, with or without cause, at any time, by action of the
holders of record of the majority of the issued and outstanding stock of the
Corporation (a) present in person or by proxy at a meeting of holders of such
stock and entitled to vote thereon or (b) by a consent in writing in the manner
contemplated in Section 9 of Article II, and the vacancy or vacancies in the
Board of Directors caused by any such removal may be filled by action of such a
majority at such meeting or at any subsequent meeting or by consent.

         Section 9.  Resignations. Any Director of the Corporation may resign at
any time by giving written notice to the Chairman of the Board, if any, the
President, the Vice President or the Secretary of the Corporation. The
resignation of any Director shall take effect upon receipt of notice thereof or
at such later time as shall be specified in such notice; and, unless otherwise
specified therein, the acceptance of such resignation shall not be necessary to
make it effective.

         Section 10. Vacancies. Any newly created directorships and vacancies
occurring in the Board by reason of death, resignation, retirement,
disqualification or removal, with or without cause, may be filled by the action
of the holders of record of the majority of the issued and outstanding stock of
the Corporation (a) present in person or by proxy at a meeting of holders of

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such stock and entitled to vote thereon or (b) by a consent in writing in the
manner contemplated in Section 9 of Article II. The Director so chosen, whether
selected to fill a vacancy or elected to a new directorship, shall hold office
until the next meeting of stockholders at which the election of Directors is in
the regular order of business, and until his successor has been elected and
qualifies, or until he sooner dies, resigns or is removed.

         Section 11. Compensation of Directors. Directors, as such, shall not
receive any stated salary for their services, but, by resolution of the Board, a
specific sum fixed by the Board plus expenses may be allowed for attendance at
each regular or special meeting of the Board; provided, however, that nothing
herein contained shall be construed to preclude any Director from serving the
Corporation or any parent or subsidiary corporation thereof in any other
capacity and receiving compensation therefor.

         Section 12. Action Without a Meeting. Any action required or permitted
to be taken at any meeting of the Board of Directors may be taken without a
meeting if a written consent thereto is signed by all members of the Board, and
such written consent is filed with the minutes or proceedings of the Board.

         Section 13. Telephonic Participation in Meetings. Members of the Board
of Directors may participate in a meeting of the Board by means of conference
telephone or similar communications equipment by means of which all persons
participating in the meeting can hear each other, and such participation shall
constitute presence in person at such meeting.

                                   ARTICLE IV
                                    OFFICERS

         Section 1.  Principal Officers. The Board of Directors shall elect a
Chief Executive Officer, a President, a Secretary and a Treasurer, and may in
addition elect a Chairman of the Board, one or more Vice Presidents and such
other officers as it deems fit; the Chief Executive Officer, the President, the
Secretary, the Treasurer, the Chairman of the Board (if any) and the Vice
Presidents (if any) being the principal officers of the Corporation. One person
may hold, and perform the duties of, any two or more of said offices.

         Section 2.  Election and Term of Office. The principal officers of the
Corporation shall be elected annually by the Board of Directors at the
organization meeting thereof. Each such officer shall hold office until his
successor shall have been elected and shall qualify, or until his earlier death,
resignation or removal.

         Section 3.  Other Officers. In addition, the Board may elect, or the
Chairman of the Board, if any, or the President may appoint, such other officers
as they deem fit. Any such other officers chosen by the Board of Directors shall
be subordinate officers and shall hold office for such period, have such
authority and perform such duties as the Board of Directors, the Chairman of the
Board, if any, or the President may from time to time determine.

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         Section 4.  Removal. Any officer may be removed, either with or without
cause, at any time, by resolution adopted by the Board of Directors at any
regular meeting of the Board, or at any special meeting of the Board called for
that purpose, at which a quorum is present.

         Section 5.  Resignations. Any officer may resign at any time by giving
written notice to the Chairman of the Board, if any, the President, the
Secretary or the Board of Directors. Any such resignation shall take effect upon
receipt of such notice or at any later time specified therein; and, unless
otherwise specified therein, the acceptance of such resignation shall not be
necessary to make it effective.

         Section 6.  Vacancies. A vacancy in any office may be filled for the
unexpired portion of the term in the manner prescribed in these By-laws for
election or appointment to such office for such term.

         Section 7.  Chairman of the Board. The Chairman of the Board of
Directors, if one be elected, shall preside if present at all meetings of the
Board of Directors, and he shall have and perform such other duties as from time
to time may be assigned to him by the Board of Directors.

         Section 8.  Chief Executive Officer. The Chief Executive Officer shall
be the chief executive officer of the Corporation and shall have the general
powers and duties of supervision and management usually vested in the office of
president of a corporation. He shall preside at all meetings of the stockholders
if present thereat, and in the absence or non-election of the Chairman of the
Board of Directors, at all meetings of the Board of Directors, and shall have
general supervision, direction and control of the business of the Corporation.
Except as the Board of Directors shall authorize the execution thereof in some
other manner, he shall execute bonds, mortgages, and other contracts on behalf
of the Corporation, and shall cause the seal to be affixed to any instrument
requiring it and when so affixed the seal shall be attested by the signature of
the Secretary or the Treasurer.

         Section 9.  President and Vice President. The President and each Vice
President, if such be elected, shall have such powers and shall perform such
duties as shall be assigned to him by the Chief Executive Officer or the Board
of Directors.

         Section 10. Treasurer. The Treasurer shall have charge and custody of,
and be responsible for, all funds and securities of the Corporation. He shall
exhibit at all reasonable times his books of account and records to any of the
Directors of the Corporation upon application during business hours at the
office of the Corporation where such books and records shall be kept; when
requested by the Board of Directors, he shall render a statement of the
condition of the finances of the Corporation at any meeting of the Board or at
the annual meeting of stockholders; he shall receive, and give receipt for,
moneys due and payable to the Corporation from any source whatsoever; in
general, he shall perform all the duties incident to the office of Treasurer and
such other duties as from time to time may be assigned to him by the Chairman of
the Board of Directors, the Chief Executive Officer or the Board of Directors.
The Treasurer shall give such bond, if any, for the faithful discharge of his
duties as the Board of Directors may require.

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         Section 11. Secretary. The Secretary, if present, shall act as
secretary at all meetings of the Board of Directors and of the stockholders and
keep the minutes thereof in a book or books to be provided for that purpose; he
shall see that all notices required to be given by the Corporation are duly
given and served; he shall have charge of the stock records of the Corporation;
he shall see that all reports, statements and other documents required by law
are properly kept and filed; and in general he shall perform all the duties
incident to the office of Secretary and such other duties as from time to time
may be assigned to him by the Chief Executive Officer or the Board of Directors.

         Section 12. Salaries. The salaries of the principal officers shall be
fixed from time to time by the Board of Directors, and the salaries of any other
officers may be fixed by the Chief Executive Officer.

                                    ARTICLE V
                    INDEMNIFICATION OF OFFICERS AND DIRECTORS

         Section 1.  Right of Indemnification. Every person now or hereafter
serving as a Director or officer of the Corporation and every such Director or
officer serving at the request of the Corporation as a director, officer,
employee or agent of another corporation, partnership, joint venture, trust or
other enterprise, shall be indemnified by the Corporation in accordance with and
to the fullest extent permitted by law for the defense of, or in connection
with, any threatened, pending or completed action, suit or proceeding, whether
civil, criminal, administrative or investigative.

         Section 2.  Expenses. Expenses incurred in defending a civil or
criminal action, suit or proceeding may be paid by the Corporation in advance of
the final disposition of such action, suit or proceeding as authorized by the
Board of Directors in the specific case upon receipt of an undertaking by or on
behalf of such Director or officer to repay such amount unless it shall
ultimately be determined that he is entitled to be indemnified by the
Corporation as authorized in this Article V.

         Section 3.  Other Rights of Indemnification. The right of
indemnification herein provided shall not be deemed exclusive of any other
rights to which any such Director or officer may now or hereafter be entitled
under any by-law, agreement, vote of stockholders or disinterested directors or
otherwise, both as to action in his official capacity and as to action in
another capacity while holding such office, and shall continue as to a person
who has ceased to be a Director or officer and shall inure to the benefit of the
heirs, executors and administrators of such person.

                                   ARTICLE VI
                            SHARES AND THEIR TRANSFER

         Section 1.  Certificate for Stock. Every stockholder of the Corporation
shall be entitled to a certificate or certificates, to be in such form as the
Board of Directors shall prescribe, certifying

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the number of shares of the capital stock of the Corporation owned by him. No
certificate shall be issued for partly paid shares.

         Section 2. Stock Certificate Signature. The certificates for such stock
shall be numbered in the order in which they shall be issued and shall be signed
by the Chairman of the Board, if any, or the President or any Vice President and
by the Secretary or an Assistant Secretary or the Treasurer of the Corporation,
and its seal shall be affixed thereto. If such certificate is countersigned (1)
by a transfer agent other than the Corporation or its employee, or, (2) by a
registrar other than the Corporation or its employee, the signatures of such
officers of the Corporation may be facsimiles. In case any officer of the
Corporation who has signed, or whose facsimile signature has been placed upon,
any such certificate shall have ceased to be such officer before such
certificate is issued, it may be issued by the Corporation with the same effect
as if he were such officer at the date of issue.

         Section 3. Stock Ledger. A record shall be kept by the Secretary or by
any other officer, employee or agent designated by the Board of Directors of the
name of each person, firm or corporation holding capital stock of the
Corporation, the number of shares represented by, and the respective dates of,
each certificate for such capital stock, and in case of cancellation of any such
certificate, the respective dates of cancellation.

         Section 4. Cancellation. Every certificate surrendered to the
Corporation for exchange or registration of transfer shall be canceled, and no
new certificate or certificates shall be issued in exchange for any existing
certificate until such existing certificate shall have been so canceled, except,
subject to Section 7 of this Article VI, in cases provided for by applicable
law.

         Section 5. Registrations of Transfers of Stock. Registrations of
transfers of shares of the capital stock of the Corporation shall be made on the
books of the Corporation by the registered holder thereof, or by his attorney
thereunto authorized by power of attorney duly executed and filed with the
Secretary of the Corporation or with a transfer clerk or a transfer agent
appointed as in Section 6 of this Article VI provided, and on surrender of the
certificate or certificates for such shares properly endorsed and the payment of
all taxes thereon. The person in whose name shares of stock stand on the books
of the Corporation shall be deemed the owner thereof for all purposes as regards
the Corporation; provided, however, that whenever any transfer of shares shall
be made for collateral security, and not absolutely, it shall be so expressed in
the entry of the transfer if, when the certificates are presented to the
Corporation for transfer, both the transferor and the transferee request the
Corporation to do so.

         Section 6. Regulations. The Board of Directors may make such rules and
regulations as it may deem expedient, not inconsistent with the Certificate of
Incorporation or these By- laws, concerning the issue, transfer and registration
of certificates for shares of the stock of the Corporation. It may appoint, or
authorize any principal officer or officers to appoint, one or more transfer
clerks or one or more transfer agents and one or more registrars, and may
require all certificates of stock to bear the signature or signatures of any of
them.

         Section 7. Lost, Stolen, Destroyed or Mutilated Certificates. Before
any certificates for stock of the Corporation shall be issued in exchange for
certificates which shall become

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mutilated or shall be lost, stolen or destroyed, proper evidence of such loss,
theft, mutilation or destruction shall be procured for the Board of Directors,
if it so requires.

         Section 8. Record Dates. For the purpose of determining the
stockholders entitled to notice of or to vote at any meeting of stockholders or
any adjournment thereof, or entitled to receive payment of any dividend or other
distribution or allotment of any rights, or entitled to exercise any rights in
respect of any change, conversion or exchange of stock or for the purpose of any
other lawful action, the Board of Directors may fix, in advance, a date as a
record date for any such determination of stockholders. Such record date shall
not be more than sixty or less than ten days before the date of such meeting, or
more than sixty days prior to any other action.

                                   ARTICLE VII
                            MISCELLANEOUS PROVISIONS

         Section 1. Corporate Seal. The Board of Directors shall provide a
corporate seal, which shall be in such form as the Board of Directors may
decide. The Secretary shall be the custodian of the seal. The Board of Directors
may authorize a duplicate seal to be kept and used by any other officer.

         Section 2. Voting of Stocks Owned by the Corporation. The Board of
Directors may authorize any person on behalf of the Corporation to attend, vote
and grant proxies to be used at any meeting of stockholders of any corporation
(except the Corporation) in which the Corporation may hold stock.

         Section 3. Dividends. Subject to the provisions of the Certificate of
Incorporation, the Board of Directors may, out of funds legally available
therefor, at any regular or special meeting declare dividends upon the capital
stock of the Corporation as and when they deem expedient. Before declaring any
dividend there may be set apart out of any funds of the Corporation available
for dividends such sum or sums as the Directors from time to time in their
discretion deem proper for working capital or as a reserve fund to meet
contingencies or for equalizing dividends or for such other purposes as the
Board of Directors shall deem conducive to the interests of the Corporation.

                                  ARTICLE VIII
                                   AMENDMENTS

         These By-laws of the Corporation may be altered, amended or repealed by
the Board of Directors at any regular or special meeting of the Board of
Directors or by the affirmative vote of the holders of record of a majority of
the issued and outstanding stock of the Corporation (i) present in person or by
proxy at a meeting of holders of such stock and entitled to vote thereon or (ii)
by a consent in writing in the manner contemplated in Section 9 of Article II,
provided, however, that notice of the proposed alteration, amendment or repeal
is contained in the notice of such meeting. By-laws, whether made or altered by
the stockholders or by the Board of Directors, shall be subject to alteration or
repeal by the stockholders as in this Article VIII above provided.

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