<PAGE>

                                                                     EXHIBIT 4.3

================================================================================


                           THIRD AMENDED AND RESTATED


                             SHAREHOLDERS AGREEMENT


                                  BY AND AMONG


                         WESTPORT RESOURCES CORPORATION

                              ERI INVESTMENTS, INC.

                               WESTPORT ENERGY LLC

                               MEDICOR FOUNDATION

                                       AND

                        CERTAIN STOCKHOLDERS NAMED HEREIN



                          DATED AS OF FEBRUARY 14, 2003


================================================================================




<PAGE>




                                TABLE OF CONTENTS

<Table>
<Caption>
                                                                                                                PAGE
                                                                                                                ----
<S>                                                                                                             <C>
ARTICLE I DEFINITIONS.............................................................................................2

         Section 1.1.      Definitions............................................................................2

ARTICLE II REPRESENTATIONS AND WARRANTIES.........................................................................6

         Section 2.1.      Representations and Warranties of the Company..........................................6
         Section 2.2.      Representations and Warranties of Medicor..............................................7
         Section 2.3.      Representations and Warranties of ERI..................................................7
         Section 2.4.      Representations and Warranties of the Belfer Group.....................................8

ARTICLE III CORPORATE GOVERNANCE; CERTAIN CORPORATE ACTIONS.......................................................8

         Section 3.1.      Voting of Shares.......................................................................8
         Section 3.2.      Composition of the Board of Directors..................................................9
         Section 3.3.      Approval of Major Actions.............................................................10
         Section 3.4.      Amendments to Articles of Incorporation and Bylaws....................................11
         Section 3.5.      Self-Interested Transactions..........................................................11

ARTICLE IV STANDSTILL............................................................................................12

         Section 4.1.      Standstill............................................................................12

ARTICLE V REGISTRATION RIGHTS....................................................................................13

         Section 5.1.      Demand Registrations..................................................................13
         Section 5.2.      Piggyback Registrations...............................................................15
         Section 5.3.      Holdback Agreements...................................................................16
         Section 5.4.      Registration Procedures...............................................................17
         Section 5.5.      Registration Expenses.................................................................19
         Section 5.6.      Indemnification.......................................................................20
         Section 5.7.      Participation in Underwritten Registrations...........................................22
         Section 5.8.      Current Public Information............................................................22
         Section 5.9.      Cooperation...........................................................................22

ARTICLE VI GENERAL PROVISIONS....................................................................................23

         Section 6.1.      Notices...............................................................................23
         Section 6.2.      Assignment; Binding Effect; Benefit...................................................25
         Section 6.3.      Entire Agreement......................................................................26
</Table>



                                      -i-

<PAGE>

<Table>
<S>                                                                                                             <C>
         Section 6.4.      Amendment.............................................................................26
         Section 6.5.      Governing Law; Jurisdiction...........................................................26
         Section 6.6.      Counterparts..........................................................................26
         Section 6.7.      Headings..............................................................................26
         Section 6.8.      Interpretation........................................................................26
         Section 6.9.      Incorporation of Exhibits and Schedules...............................................26
         Section 6.10.     Severability..........................................................................26
         Section 6.11.     Enforcement of Agreement..............................................................27
         Section 6.12.     Confidentiality.......................................................................27
         Section 6.13.     Termination...........................................................................27
         Section 6.14.     Belfer Group Representative...........................................................27
         Section 6.15.     Medicor Group Representative..........................................................28
         Section 6.16.     Effective Time........................................................................28
</Table>



                                      -ii-


<PAGE>
                           THIRD AMENDED AND RESTATED
                             SHAREHOLDERS AGREEMENT

         This THIRD AMENDED AND RESTATED SHAREHOLDERS AGREEMENT, dated as of
February 14, 2003 (this "Agreement"), is entered into by and among Westport
Resources Corporation, a Nevada corporation ("Westport" or the "Company"),
Westport Energy LLC, a Delaware limited liability company ("WELLC"), ERI
Investments, Inc., a Delaware corporation ("ERI"), Medicor Foundation, a
Liechtenstein foundation, formed pursuant to the Liechtenstein Persons and
Companies Act ("Medicor," and together with WELLC, the "Medicor Group") and the
persons and entities named on Exhibit A (each such person or entity, a "Belfer
Person," and collectively, the "Belfer Group").

         WHEREAS, Westport Oil and Gas Company, Inc. ("WOGC"), Equitable
Production Company ("EPC"), Equitable Production (Gulf) Company ("EPGC"),
Westport Energy Corporation ("WEC") and EPGC Merger Sub Corporation ("Merger
Sub") entered into a Merger Agreement dated as of March 9, 2000 (the "EPGC
Merger Agreement") providing for the merger of Merger Sub with and into WOGC and
for the conversion of the WOGC capital stock held by WEC into shares of EPGC
capital stock, such that immediately after the merger, EPC owned approximately
49% of the capital stock of EPGC and WEC owned approximately 51% of the capital
stock of EPGC (the "EPGC Merger"); and

         WHEREAS, as a condition to the consummation of the transactions
contemplated by the EPGC Merger Agreement, WEC, EPC and EPGC entered into that
certain Shareholders Agreement dated as of March 9, 2000 (the "Original
Shareholders Agreement"); and

         WHEREAS, subsequent to the EPGC Merger, EPC assigned its interest in
EPGC to ERI, WEC became WELLC by statutory conversion, and EPGC changed its name
to Westport Resources Corporation; and

         WHEREAS, Westport Resources Corporation, a Delaware corporation ("Old
Westport") and Belco Oil & Gas Corp., a Nevada corporation ("Belco") entered
into an Agreement and Plan of Merger dated as of June 8, 2001 (the "Merger
Agreement") providing for, among other things, the merger (the "Merger") of Old
Westport with and into Belco, with Belco as the surviving corporation, and for
the conversion of 100% of the issued and outstanding shares of Old Westport
Common Stock, par value $.01 per share ("Old Westport Common Stock") into Common
Stock (as hereinafter defined) and the automatic cancellation and retirement of
the Old Westport Common Stock; and

         WHEREAS, concurrently with the execution and delivery of the Merger
Agreement, Belco, Old Westport, WELLC, ERI and the Belfer Group (as then
comprised, the "Original Belfer Group") entered into an Amended and Restated
Shareholders Agreement (the "Amended Shareholders Agreement"), the purpose of
which was to amend and restate the Original Shareholders Agreement to reflect
the effects of the Merger by, among other things, (i) having it apply to the
shares of Common Stock issued to WELLC and ERI in connection with the Merger in
exchange for their Old Westport Common Stock and (ii) adding Belco and the
Original Belfer Group as parties; and


<PAGE>

         WHEREAS, Belco, Westport, WELLC, ERI and the Original Belfer Group
entered into a Second Amended and Restated Shareholders Agreement dated as of
July 20, 2001 (the "Second Amended and Restated Shareholders Agreement") to
effect certain modifications to the Amended Shareholders Agreement; and

         WHEREAS, subsequent to the Merger, Belco changed its name to Westport
Resources Corporation; and

         WHEREAS, WELLC has transferred certain of its shares of Common Stock to
Medicor; and

         WHEREAS, certain Persons in the Original Belfer Group have made various
Transfers to Permitted Transferees, changing the composition of the Original
Belfer Group; and

         WHEREAS, the purpose of this Agreement is to effect certain
modifications relating to the transfer of Common Stock by WELLC to Medicor,
certain Transfers to Permitted Transferees made by Persons in the Original
Belfer Group and to amend and restate such Second Amended and Restated
Shareholders Agreement, as so modified, in its entirety;

         NOW, THEREFORE, in consideration of the foregoing, and of the
representations, warranties, covenants and agreements contained herein, and for
other good and valuable consideration, the receipt and sufficiency of which is
hereby acknowledged, the parties hereto, intending to be legally bound, hereby
agree as follows:

                                   ARTICLE I
                                   DEFINITIONS

         Section 1.1. Definitions.

         "Affiliate" shall have the meaning set forth in Rule 12b-2 of the
regulations promulgated under the Exchange Act.

         "Agreement" shall have the meaning set forth in the preamble to this
Agreement.

         "Amended Shareholders Agreement" shall have the meaning set forth in
the preamble to this Agreement.

         "Belco" shall have the meaning set forth in the preamble to this
Agreement.

         "Belfer Group" shall have the meaning set forth in the preamble to this
Agreement.

         "Belfer Group Representative" shall have the meaning set forth in
Section 6.14.

         "Belfer Parties" shall mean the Belfer Group and their Permitted
Transferees.

         "Belfer Person" shall mean any Person included in the Belfer Group.

         "Board of Directors" shall mean the board of directors of the Company.



                                      -2-
<PAGE>

         "Commission" shall mean the Securities and Exchange Commission or any
other Federal agency at the time administering the Securities Act.

         "Common Stock" shall mean the common stock of the Company, par value
$.01 per share, now or hereafter authorized to be issued.

         "Company" shall have the meaning set forth in the preamble to this
Agreement.

         "Consolidated Net Worth" shall mean, at any particular time, all
amounts which, in conformity with GAAP, would be included as common
stockholders' equity on a consolidated balance sheet of the Company and its
Subsidiaries.

         "Debt" shall mean (a) Funded Debt, plus (b) at any particular time, all
amounts which, in conformity with GAAP, would be included as preferred
stockholders' equity on a consolidated balance sheet of the Company and its
Subsidiaries less (c) cash of the Company and its Subsidiaries.

         "Demand Registrations" shall have the meaning set forth in Section
5.l(a).

         "Director" shall mean a member of the Board of Directors.

         "Disinterested Director" shall have the meaning set forth in Section
3.5.

         "Effective Time" shall have the meaning set forth in Section 6.16.

         "EPC" shall have the meaning set forth in the preamble to this
Agreement.

         "EPGC" shall have the meaning set forth in the preamble to this
Agreement.

         "EPGC Merger" shall have the meaning set forth in the preamble to this
Agreement.

         "EPGC Merger Agreement" shall have the meaning set forth in the
preamble to this Agreement.

         "ERI" shall have the meaning set forth in the preamble to this
Agreement.

         "ERI Parties" shall mean ERI and its Permitted Transferees.

         "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder, all as the
same shall be in effect at the time.

         "Funded Debt" shall mean at any time (without duplication): (a) all
obligations of the Company and its Subsidiaries, or any of them, for borrowed
money and all obligations of the Company and its Subsidiaries, or any of them,
evidenced by bonds, notes, debentures, or other similar instruments, (b) all
capital lease obligations of the Company and its Subsidiaries, or any of them,
(c) all debt or other obligations of others guaranteed by the Company and its
Subsidiaries, or any of them to the extent of such guarantee, (d) all
reimbursement obligations of the Company and its Subsidiaries, or any of them
(whether contingent or otherwise) in respect of



                                      -3-
<PAGE>

letters of credit, bankers' acceptances, surety or other bonds and similar
instruments, (e) all obligations of the Company and its Subsidiaries, or any of
them, to pay the deferred purchase price of property or services, except trade
accounts payable of the Company and its Subsidiaries, or any of them, arising in
the ordinary course of business that are not past due by more than ninety (90)
days, (f) all obligations secured by a lien existing on property owned by the
Company and its Subsidiaries, or any of them, whether or not the obligations
secured thereby have been assumed by the Company and its Subsidiaries, or any of
them, or are non-recourse to the credit of the Company and its Subsidiaries, or
any of them, and (g) all other debt of the Company and its Subsidiaries, or any
of them.

         "GAAP" shall mean generally accepted accounting principles in the
United States.

         "Independent Director" shall mean an individual (i) who is not a
director, officer, employee or Affiliate of the Company, WELLC, Medicor, the
Belfer Group or ERI, or any of their respective Affiliates, (ii) who is not a
former director, officer or employee of the Company, Old Westport, WELLC,
Medicor, the Belfer Group or ERI, or any of their respective Affiliates, (iii)
who has not had and who is not a director, officer, 10% or more equity owner or
Affiliate of any Person that has had a direct or indirect interest in any
transaction in the preceding 24 months with the Company, Old Westport, WELLC,
Medicor, the Belfer Group or ERI, or any of their respective Affiliates, and
(iv) who does not represent the Company, WELLC, Medicor, the Belfer Group or
ERI, or any of their respective Affiliates, and any Independent Director
appointed shall be required to certify in writing to this effect upon request.

         "Major Actions" shall mean those actions described in Sections 3.3.

         "Medicor" shall have the meaning set forth in the preamble to this
Agreement.

         "Medicor Group" shall have the meaning set forth in the preamble to
this Agreement.

         "Medicor Group Representative" shall have the meaning set forth in
Section 6.15.

         "Medicor Parties" shall mean the Medicor Group and their Permitted
Transferees.

         "Medicor Person" shall mean any Person included in the Medicor Group.

         "Merger" shall have the meaning set forth in the preamble to this
Agreement.

         "Merger Agreement" shall have the meaning set forth in the preamble to
this Agreement.

         "Merger Sub" shall have the meaning set forth in the preamble to this
Agreement.

         "Old Westport" shall have the meaning set forth in the preamble to this
Agreement.

         "Old Westport Common Stock" shall have the meaning set forth in the
preamble to this Agreement.



                                      -4-
<PAGE>

         "Original Belfer Group" shall have the meaning set forth in the
preamble to this Agreement.

         "Original Shareholders Agreement" shall have the meaning set forth in
the preamble to this Agreement.

         "Party" or "Parties" shall mean ERI, the Medicor Group and/or the
Belfer Group.

         "Permitted Transferees" shall mean in the case of the Medicor Parties:
(A) a Medicor Person, any spouse, issue, parent or relatives of the Medicor
Parties, or (i) trusts for the benefit of any of such Persons, (ii) entities
controlling or controlled by any of such Persons and (iii) in the event of the
death of any such individual person, heirs or testamentary legatees of such
person, in each case to whom a Medicor Party has transferred its Shares and who
has agreed in writing to be bound by the terms of this Agreement, and (B) any
Subsidiary or Affiliate of the Medicor Group to which a Medicor Party has
transferred its Shares and which has agreed in writing to be bound by the terms
of this Agreement; in the case of the ERI Parties: (A) ERI, any spouse, issue,
parent or relatives of the ERI Parties, or (i) trusts for the benefit of any of
such Persons, (ii) entities controlling or controlled by any of such Persons and
(iii) in the event of the death of any such individual person, heirs or
testamentary legatees of such person, in each case to whom an ERI Party has
transferred its Shares and who has agreed in writing to be bound by the terms of
this Agreement, and (B) any Subsidiary or Affiliate of ERI to which an ERI Party
has transferred its Shares and which has agreed in writing to be bound by the
terms of this Agreement; and in the case of the Belfer Parties: a Belfer Person,
any spouse, issue, parent or relatives of the Belfer Parties, or (i) trusts for
the benefit of any of such Persons, (ii) entities controlling or controlled by
any of such Persons and (iii) in the event of the death of any such individual
person, heirs or testamentary legatees of such person, in each case to whom a
Belfer Party has transferred its Shares and who has agreed in writing to be
bound by the terms of this Agreement;

         "Person" shall mean any natural person, corporation, partnership,
limited liability company, firm, association, trust, government, governmental
agency or other entity, whether acting in an individual, fiduciary or other
capacity.

         "Piggyback Registration" shall have the meaning set forth in Section
5.2(a).

         "Registrable Securities" shall mean (i) any shares of Common Stock
owned by, or otherwise hereafter acquired by, the Medicor Parties, the ERI
Parties or the Belfer Parties, and (ii) any securities issued as a dividend on
or other distribution with respect to or in exchange, replacement or in
subdivision of, any such Common Stock. As to any particular Registrable
Securities, such securities shall cease to be Registrable Securities when (A) a
registration statement (other than the Form S-4 pursuant to which the issuance
of Common Stock in connection with the Merger is registered under the Securities
Act) with respect to the sale of such securities shall have been declared
effective under the Securities Act and such securities shall have been disposed
of in accordance with such registration statement, or (B) such securities shall
have been sold (other than in a privately negotiated sale) pursuant to Rule 144
(or any successor provision) under the Securities Act.



                                      -5-
<PAGE>

         "Registration Expenses" shall have the meaning set forth in Section
5.5(a).

         "Second Amended and Restated Shareholders Agreement" shall have the
meaning set forth in the preamble to this Agreement.

         "Securities Act" shall mean the Securities Act of 1933, as amended, and
the rules and regulations of the Commission thereunder, as the same shall be in
effect at the time.

         "Self-Interested Transaction" shall have the meaning set forth in
Section 3.5.

         "Shares" shall mean shares of Common Stock.

         "Short-Form Registrations" shall have the meaning set forth in Section
5.l(a).

         "Subsidiary" of any Person shall mean any corporation or other legal
entity of which such Person (either alone or through or together with any other
Subsidiary) owns, directly or indirectly, 50% or more of the stock or other
equity interests, the holders of which are generally entitled to vote for the
election of the board of directors or other governing body of such corporation
or other legal entity.

         "Supermajority Approval" shall mean approval by action of at least a
majority of all of the members of the Board of Directors which shall include not
less than one less than all of the Directors whom the Parties then have the
right to nominate pursuant to Section 3.2.

         "Total Capitalization" shall mean the sum of (i) Consolidated Net Worth
and (ii) Debt.

         "Transfer" shall mean to sell, transfer, assign, pledge or otherwise
dispose.

         "underwriter" shall mean nationally recognized investment banking firm
with experience serving as lead managing underwriter for public offerings of the
stock of companies engaged in the exploration, development and production of oil
and natural gas.

         "WEC" shall have the meaning set forth in the preamble to this
Agreement.

         "WELLC" shall have the meaning set forth in the preamble to this
Agreement.

         "Westport" shall have the meaning set forth in the preamble to this
Agreement.

         "WOGC" shall have the meaning set forth in the preamble to this
Agreement.

                                   ARTICLE II
                         REPRESENTATIONS AND WARRANTIES

         Section 2.1. Representations and Warranties of the Company. The Company
hereby represents and warrants to the other Parties hereto as follows: The
Company has all requisite corporate power and authority to enter into this
Agreement and to consummate the transactions contemplated hereby. The execution
and delivery by the Company of this Agreement, and the consummation by the
Company of the transactions contemplated hereby, have been duly



                                      -6-
<PAGE>

authorized by all necessary corporate action on the part of the Company. This
Agreement has been duly executed and delivered by the Company and constitutes a
valid and binding obligation of the Company enforceable against the Company in
accordance with its terms. No consent, approval, order or authorization of, or
registration, declaration or filing with, any court, administrative agency or
commission or other governmental authority or instrumentality, domestic or
foreign, is required by, or with respect to, the Company in connection with the
execution and delivery of this Agreement by the Company or the consummation by
the Company of the transactions contemplated hereby. The execution and delivery
of this Agreement by the Company and the consummation of the transactions
contemplated hereby by the Company does not conflict with, or result in a breach
of, any law or regulation of any governmental authority applicable to the
Company or any material agreement to which the Company is a party.

         Section 2.2. Representations and Warranties of Medicor. Each Medicor
Person hereby severally and not jointly represents and warrants to the other
Parties hereto as follows:

                  (a) Authority. Each Medicor Person has all requisite corporate
or other power and authority to enter into this Agreement and to consummate the
transactions contemplated hereby. The execution and delivery by such Medicor
Person of this Agreement, and the consummation by such Medicor Person of the
transactions contemplated hereby, have been duly authorized by all necessary
corporate or other action on the part of such Medicor Person. This Agreement has
been duly executed and delivered by such Medicor Person and constitutes a valid
and binding obligation of such Medicor Person enforceable against such Medicor
Person in accordance with its terms. No consent, approval, order or
authorization of, or registration, declaration or filing with, any court,
administrative agency or commission or other governmental authority or
instrumentality, domestic or foreign, is required by, or with respect to, such
Medicor Person in connection with the execution and delivery of this Agreement
by such Medicor Person or the consummation by such Medicor Person of the
transactions contemplated hereby. The execution and delivery of this Agreement
by such Medicor Person and the consummation by such Medicor Person of the
transactions contemplated hereby by it do not conflict with, or result in a
breach of, any law or regulation of any governmental authority applicable to
such Medicor Person or any material agreement to which such Medicor Person is a
party.

                  (b) Shares. Schedule 2.2 sets forth the ownership of the
Shares held by each Medicor Person as of the date hereof.

         Section 2.3. Representations and Warranties of ERI. ERI hereby
represents and warrants to the other Parties hereto as follows:

                  (a) Authority. Each of the ERI Parties has all requisite
corporate or other power and authority to enter into this Agreement and to
consummate the transactions contemplated hereby. The execution and delivery by
the ERI Parties of this Agreement and the consummation by the ERI Parties of the
transactions contemplated hereby have been duly authorized by all necessary
corporate or other action on the part of each of the ERI Parties. This Agreement
has been duly executed and delivered by each of the ERI Parties and constitutes
a valid and binding obligation of each of the ERI Parties enforceable against
each of the ERI Parties in accordance with its terms. No consent, approval,
order or authorization of, or



                                      -7-
<PAGE>

registration, declaration or filing with, any court, administrative agency or
commission or other governmental authority or instrumentality, domestic or
foreign, is required by, or with respect to, any of the ERI Parties in
connection with the execution and delivery of this Agreement by the ERI Parties
or the consummation by each of the ERI Parties of the transactions contemplated
hereby. The execution and delivery by the ERI Parties of this Agreement and the
consummation by the ERI Parties of the transactions contemplated hereby do not
conflict with, or result in a breach of, any law or regulation of any
governmental authority applicable to any of the ERI Parties or any material
agreement to which any of the ERI Parties is a party.

                  (b) Shares. Schedule 2.3 sets forth the ownership of the
Shares held by the ERI Parties as of the date hereof.

         Section 2.4. Representations and Warranties of the Belfer Group. Each
Belfer Person hereby severally and not jointly represents and warrants to the
other Parties hereto as follows:

                  (a) Authority. Such Belfer Person has all requisite corporate
or other power and authority to enter into this Agreement and to consummate the
transactions contemplated hereby. The execution and delivery by such Belfer
Person of this Agreement, and the consummation by such Belfer Person of the
transactions contemplated hereby, have been duly authorized by all necessary
corporate or other action on the part of such Belfer Person. This Agreement has
been duly executed and delivered by such Belfer Person and constitutes a valid
and binding obligation of such Belfer Person enforceable against such Belfer
Person in accordance with its terms. No consent, approval, order or
authorization of, or registration, declaration or filing with, any court,
administrative agency or commission or other governmental authority or
instrumentality, domestic or foreign, is required by, or with respect to, such
Belfer Person in connection with the execution and delivery of this Agreement by
such Belfer Person or the consummation by such Belfer Person of the transactions
contemplated hereby. The execution and delivery of this Agreement by such Belfer
Person and the consummation by such Belfer Person of the transactions
contemplated hereby by it do not conflict with, or result in a breach of, any
law or regulation of any governmental authority applicable to such Belfer Person
or any material agreement to which such Belfer Person is a party.

                  (b) Shares. Schedule 2.4 sets forth the ownership of the
Shares held by each Belfer Person as of the date hereof.

                                  ARTICLE III
                 CORPORATE GOVERNANCE; CERTAIN CORPORATE ACTIONS

         Section 3.1. Voting of Shares.

                  (a) The Medicor Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
actions within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.



                                      -8-
<PAGE>

                  (b) The ERI Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
action within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.

                  (c) The Belfer Parties shall vote all shares of Common Stock
owned or controlled by them, and shall take all other necessary or desirable
action within their control (including, without limitation, attendance at
meetings in person or by proxy for purposes of obtaining a quorum and execution
of written consents in lieu of meetings), to effectuate the provisions of this
Agreement.

                  (d) The Company shall take all necessary or desirable actions
within its control (including, without limitation, calling special board and
stockholder meetings) to effectuate the provisions of this Agreement.

         Section 3.2. Composition of the Board of Directors. (i) The Medicor
Parties shall vote all shares of Common Stock owned or controlled by them, and
shall take all necessary action within their control, (ii) the ERI Parties shall
vote all shares of Common Stock owned or controlled by them, and shall take all
necessary actions within their control and (iii) the Belfer Parties shall vote
all shares of Common Stock owned or controlled by them, and shall take all
necessary action within their control, in each case, so that the composition of
the Board of Directors and the manner of selecting members thereof shall be as
follows:

                  (a) The Board of Directors shall be comprised of eleven (11)
Directors (two of whom shall be Independent Directors) divided into three
classes, with Directors in each class having a three-year term following a
transition period in which the initial Class 1 Directors serve a one-year term,
the initial Class 2 Directors serve a two-year term and the initial Class 3
Directors serve a three-year term. Medicor and ERI shall each have the right to
nominate one (1) Director to Class 3, one (1) Director to Class 2 and one (1)
Director to Class 1 and the Belfer Group shall have the right to nominate one
(1) Director to Class 3 and one (1) Director to Class 1; provided, that the
existing membership of the Board of Directors and the class to which each
director nominee belongs shall not be affected by the execution of this
Agreement. Each of Medicor, ERI and the Belfer Group, respectively, shall have
the right: (i) subject to applicable law, including Nevada Revised Statutes
78.335(1) requiring a vote of not less than two-thirds of the issued and
outstanding voting power to remove an incumbent director, to remove, with or
without cause, any Director nominated in accordance with this Section 3.2 by
Medicor, ERI or the Belfer Group, respectively, and each of the Medicor Parties,
the ERI Parties and the Belfer Parties shall vote their Shares in furtherance of
this provision; and (ii) to nominate any replacement for a Director nominated in
accordance with this Section 3.2 by Medicor, ERI or the Belfer Group,
respectively, upon the death, resignation, retirement, disqualification or
removal from office of such Director. The Board of Directors shall duly appoint
as a Director each person so nominated to fill a vacancy on the Board of
Directors. Notwithstanding the foregoing:

                           (i) if either the Medicor Parties or the ERI Parties
own less than 18% of the Company's then outstanding Common Stock, then Medicor
or ERI, as the case may be,



                                      -9-
<PAGE>

shall have the right to nominate only: (x) one (1) Director to the class of
Directors having the then longest remaining term; and (y) one (1) Director to
the class of Directors having the next longest remaining term; provided that in
either case, if necessary to put one or more of a Party's Director nominees into
such classes, the Company and the other Parties shall cooperate as necessary to
effect such nomination; provided, further, that the right to change such classes
may only be exercised in connection with the reduction in the number of the
Party's Director nominees;

                           (ii) if either the Medicor Parties, the ERI Parties
or the Belfer Parties own less than 8% of the Company's then outstanding Common
Stock, then Medicor, ERI or the Belfer Group, as the case may be, shall have the
right to nominate only one (1) Director to the class of Directors having the
then longest remaining term; provided that if necessary to put a Party's
Director nominee into such class, the Company and the other Parties shall
cooperate as necessary to effect such nomination; provided, further, that the
right to change such classes may only be exercised in connection with the
reduction in the number of the Party's Director nominees; and

                           (iii) if either the Medicor Parties, the ERI Parties
or the Belfer Parties own less than 5% of the Company's then outstanding Common
Stock, then Medicor, ERI or the Belfer Group, as the case may be, shall not have
the right to nominate any Directors.

                  (b) For so long as any Party has the right to nominate a
Director under this Agreement, the Company will give such Party written notice
of each regularly scheduled meeting of its Board of Directors as far in advance
as such notice is required to be delivered to the Directors (and at least three
business days prior to the date of each special meeting of the Board of
Directors), and the Board of Directors will permit up to two (2) representatives
of each such Party to attend as observers of all meetings of the Board of
Directors (including any meetings of committees thereof); provided that in the
case of telephonic meetings conducted in accordance with the Company's bylaws
and applicable law, each such Party's representatives will be given the
opportunity to listen to such telephonic meetings. Each representative will be
entitled to receive all written materials and other information (including,
without limitation, copies of meeting minutes and press releases) given to
Directors in connection with such meetings at the same time such materials and
information are given to the Directors. If the Board of Directors proposes to
take any action by written consent in lieu of a meeting of the Board of
Directors or of any committee thereof, the Company will give written notice
thereof to each such Party who has the right to nominate a director under this
Agreement prior to the effective date of such consent describing in reasonable
detail the nature and substance of such action. The Company will reimburse each
Party that has observer rights under this Section 3.2(b) for all reasonable
expenses incurred by such Party's representatives in connection with attending
meetings of the Board of Directors and committees thereof.

         Section 3.3. Approval of Major Actions. The Company may take and may
permit its Subsidiaries to take and engage in the following Major Actions only
upon receiving Supermajority Approval:



                                      -10-
<PAGE>

                  (a) Issuance of Capital Stock. Any issuance, sale, grant or
award or entering into any agreement to issue, sell, grant or award any capital
stock of the Company other than (i) pursuant to agreements or obligations in
existence prior to the date hereof and permitted under the terms of the Second
Amended and Restated Shareholders Agreement, (ii) the issuance of capital stock
of the Company pursuant to any rights or agreements including without limitation
any security convertible or exchangeable into or exercisable for, with or
without consideration, capital stock of the Company so long as such rights or
agreements received Supermajority Approval and (iii) the grant of options and
the issuance of restricted stock under Company stock incentive plans for the
benefit of the Company's employees and directors and the issuance of Common
Stock upon the exercise of such options.

                  (b) Debt to Total Capitalization. Incur Funded Debt of the
Company and its Subsidiaries so that the ratio of Debt of the Company and its
Subsidiaries to Total Capitalization is greater than 0.4 to 1.0.

                  (c) Sale Transactions. Any merger or consolidation of the
Company, the sale of all or substantially all of the assets of the Company or
the sale of assets or transfer to a third party by sale of assets, merger or
otherwise by the Company or any of its Subsidiaries (in one transaction or a
series of related transactions) of any Subsidiary of the Company or the assets
or business of the Company or a Subsidiary thereof which involves more than $150
million (or such other amount, established by resolution of the Board of
Directors (approved by Supermajority Approval) from time to time), of the total
assets of the Company and its Subsidiaries taken as a whole, including a sale of
the Company effected by means of a sale of Common Stock, but excluding, however,
dispositions of assets in the ordinary course of business (including, but not
limited to, oil and gas production).

         Section 3.4. Amendments to Articles of Incorporation and Bylaws. The
Company, the Medicor Parties, the ERI Parties and the Belfer Parties shall take
or cause to be taken all lawful action necessary to ensure at all times that the
Company's Articles of Incorporation and Bylaws are at all times consistent with
the provisions of this Agreement.

         Section 3.5. Self-Interested Transactions. The consummation, amendment,
restatement, substitution or modification of any contract, agreement,
transaction or other arrangement between the Company or any Subsidiary of the
Company and any Medicor Person, ERI, any Belfer Person or any Affiliate of any
Medicor Person, ERI or any Belfer Person (a "Self-Interested Transaction") shall
require, except when the economic effect to the Company of any such action (or
set of related actions) is $50,000 or less, the affirmative vote of a majority
of the Disinterested Directors present at a duly called and noticed meeting at
which a quorum is present. "Disinterested Directors" shall include all Directors
not nominated by the Medicor Group, ERI or the Belfer Group which is or whose
Affiliate is a party to the Self-Interested Transaction (other than any
Independent Directors).



                                      -11-
<PAGE>

                                   ARTICLE IV
                                   STANDSTILL

         Section 4.1. Standstill.

                  (a) The Medicor Group agrees that from and after the date
hereof it will not, and will not act in concert with any Person so as to form a
group (as such term is defined in Regulation 13D promulgated under the Exchange
Act) to, in any manner, acquire, agree to acquire or make any proposal to
acquire, directly or indirectly, beneficial ownership (as such term is defined
in Regulation 13D promulgated under the Exchange Act) of any additional
securities or debt instruments of the Company or any Subsidiary of the Company
without the consent of ERI, so long as the ERI Parties hold at least 5% of the
then outstanding Common Stock, and the Belfer Group, so long as the Belfer
Parties hold at least 5% of the then outstanding Common Stock. The restrictions
set forth in this Section 4.1(a) shall not apply (i) so long as (A) the Medicor
Parties do not beneficially own more than 30% of the then outstanding Common
Stock or (B) the Medicor Parties, make an offer in writing to the Company's
Board of Directors to acquire for cash all of the outstanding Common Stock not
then held by it and the Board of Directors (including a majority of the
Disinterested Directors) approves the offer after receipt of a written fairness
opinion from a nationally recognized investment banking firm to the effect that
the consideration to be paid in the transaction is fair from a financial point
of view to all shareholders of the Company (other than the offering shareholder)
or (ii) if each of the ERI Parties and the Belfer Parties hold less than 5% of
the then outstanding Common Stock.

                  (b) ERI agrees that from and after the date hereof it will
not, and that it will cause its Subsidiaries not to, and will not act in concert
with any Person so as to form a group (as such term is defined in Regulation 13D
promulgated under the Exchange Act) to, in any manner, acquire, agree to acquire
or make any proposal to acquire, directly or indirectly, beneficial ownership
(as such term is defined in Regulation 13D promulgated under the Exchange Act)
of any additional securities or debt instruments of the Company or any
Subsidiary of the Company without the consent of the Medicor Group, so long as
the Medicor Parties hold at least 5% of the then outstanding Common Stock, and
the Belfer Group, so long as the Belfer Parties hold at least 5% of the then
outstanding Common Stock. The restrictions set forth in this Section 4.1(b)
shall not apply (i) so long as (A) ERI does not beneficially own more than 30%
of the then outstanding Common Stock or (B) ERI makes an offer in writing to the
Company's Board of Directors to acquire for cash all of the outstanding Common
Stock not then held by it and the Board of Directors (including a majority of
the Disinterested Directors) approves the offer after receipt of a written
fairness opinion from a nationally recognized investment banking firm to the
effect that the consideration to be paid in the transaction is fair from a
financial point of view to all shareholders of the Company (other than the
offering shareholder) or (ii) if each of the Medicor Parties and the Belfer
Parties hold less than 5% of the then outstanding Common Stock.

                  (c) The Belfer Group agrees that from and after the date
hereof they will not, and will not act in concert with any Person so as to form
a group (as such term is defined in Regulation 13D promulgated under the
Exchange Act) to, in any manner, acquire, agree to acquire or make any proposal
to acquire, directly or indirectly, beneficial ownership (as such term is
defined in Regulation 13D promulgated under the Exchange Act) of any additional



                                      -12-
<PAGE>

securities or debt instruments of the Company or any Subsidiary of the Company
without the consent of the Medicor Group, so long as the Medicor Parties hold at
least 5% of the then outstanding Common Stock, and ERI, so long as the ERI
Parties hold at least 5% of the then outstanding Common Stock. The restrictions
set forth in this Section 4.1(c) shall not apply (i) so long as (A) the Belfer
Parties do not beneficially own more than 20% of the then outstanding Common
Stock or (B) the Belfer Parties make an offer in writing to the Company's Board
of Directors to acquire for cash all of the outstanding Common Stock not then
held by it and the Board of Directors (including a majority of the Disinterested
Directors) approves the offer after receipt of a written fairness opinion from a
nationally recognized investment banking firm to the effect that the
consideration to be paid in the transaction is fair from a financial point of
view to all shareholders of the Company (other than the offering shareholder) or
(ii) if each of the Medicor Parties and the ERI Parties hold less than 5% of the
then outstanding Common Stock.

                                   ARTICLE V
                               REGISTRATION RIGHTS

         Section 5.1. Demand Registrations.

                  (a) Requests for Registration. Each of the Medicor Group, on
behalf of the Medicor Parties, ERI, on behalf of the ERI Parties, and the Belfer
Group, on behalf of the Belfer Parties, shall have the right to request
registration under the Securities Act of all or part of their Registrable
Securities on Form S-1 or any similar long-form registration or, if available,
on Form S-2 or S-3 or any similar short-form registration ("Short-Form
Registrations") in accordance with this Article V. All registrations requested
pursuant to this Section 5.l(a) are referred to herein as "Demand
Registrations."

                  (b) Short-Form Registrations. Demand Registrations will be
Short-Form Registrations whenever the Company is permitted to use any applicable
short form. The Company will use its best efforts to make Short-Form
Registrations available for the sale of Registrable Securities. Demand
Registration requests may be for shelf registrations if the Company is then
eligible to effect shelf registrations.

                  (c) Restrictions on Demand Registrations. The registration
rights granted under this Section 5.1 are expressly subject to the following
terms and conditions:

                           1. The Company will not be obligated to effect any
Demand Registration within six (6) months after the effective date of a previous
Demand Registration.

                           2. The Company may postpone for up to ninety (90)
days the filing or the effectiveness of a registration statement for a Demand
Registration if the Company notifies the Party initiating the Demand
Registration within fifteen (15) days after receipt of request for such
registration (i) that the Company is at such time conducting or about to conduct
an underwritten public offering of its securities for its own account and the
Board of Directors has determined in its good faith judgment that such offering
would be materially adversely effected by such registration requested by such
Party or (ii) that the Board of Directors has determined, in its good faith
judgment, that such Demand Registration would reasonably be expected to have an



                                      -13-
<PAGE>

adverse effect on any proposal or plan by the Company or any of its Subsidiaries
to engage in any acquisition of assets (other than in the ordinary course of
business) or any merger, consolidation, tender offer or similar transaction;
provided, that, in such event, the holders of Registrable Securities initially
requesting such Demand Registration will be entitled to withdraw such request
and, if such request is withdrawn, such Demand Registration will not count as a
Demand Registration hereunder and the Company will pay all Registration Expenses
in connection with such request.

                           3. Any request for a Demand Registration shall not be
otherwise deemed to be effective unless such request includes the lesser of (i)
at least ten percent (10%) of the Company's outstanding Common Stock or (ii) all
of the Common Stock owned by the Parties making the request. Each request for a
Demand Registration shall specify the approximate number of Registrable
Securities requested to be registered and the anticipated per share price range
for such offering.

                           4. The Medicor Parties and the ERI Parties shall each
be entitled to initiate only three (3) Demand Registrations and the Belfer
Parties shall be entitled to initiate only two (2) Demand Registrations to
register Registrable Securities under the terms of this Section 5.1; provided,
if one of such Parties joins in the Demand Registration initiated by the other
in accordance with Section 5.1(c)(5), the initiating Party shall not be deemed
to have initiated the Demand Registration for purposes (and solely for the
purposes) of the limitation contained in this sentence.

                           5. If at any time or from time to time any of the
Parties shall request registration of any Registrable Securities in accordance
with this Section 5.1, the Company shall give the other Parties prompt written
notice of the proposed registration. The other Parties shall have the right to
join in such registration by giving notice to the Company within five (5)
business days after such Party receives notice of the proposed registration from
the Company and the Company shall include in such registration the number of
Registrable Securities requested by such other Parties on the same terms and
conditions as the Registrable Securities of the Party initiating the request. If
the managing underwriter or underwriters of a proposed offering for which
securities of more than one of the Parties are included pursuant to this Section
5.1(c)(5) advise the Company in writing that in its or their good faith judgment
the total amount of securities to be included in such offering exceeds the
number which can be sold in such offering within a price range reasonably
acceptable to the Parties, then in such event the securities to be included in
such offering shall be allocated pro rata among each such Parties and their
Permitted Transferees participating in the offering based upon the number of
Shares owned by each such Party and its Permitted Transferees.

                           6. Any registration statement filed on Form S-3
pursuant to Rule 415 of the Securities Act covering Registrable Securities shall
be restricted for use pursuant to a firmly underwritten offering of Common
Stock; provided, however, that a shelf registration statement filed under Rule
415 will not require a firm commitment underwritten offering for (i) sales of
Common Stock constituting block sales of less than five percent (5%) of the
Common Stock outstanding to institutional investors in solicited transactions,
or (ii) sales into the market in unsolicited brokers transactions if the total
amount of shares registered for sale in this manner



                                      -14-
<PAGE>

involves less than ten percent (10%) of the shares of Common Stock then
outstanding. Each offering of Registrable Securities under this Section 5.1
pursuant to a shelf registration statement under Rule 415, other than offers and
sales of Common Stock pursuant to subsections (i) and (ii) of the preceding
sentence, shall be treated as a Demand Registration (other than for purposes of
Section 5.1(c)(1)) and must satisfy all requirements for a Demand Registration.

                  (d) Other Registration Rights. The Company will not grant to
any Person the right to request the Company to register any equity securities of
the Company with terms more favorable to such Person than those granted in this
Agreement without the prior written consent of the Medicor Group, ERI and the
Belfer Group.

         Section 5.2. Piggyback Registrations.

                  (a) Right to Piggyback. Whenever the Company proposes to
register any of its equity securities under the Securities Act (other than a
registration on Form S-4 or Form S-8 or any successor or similar forms and other
than a Demand Registration pursuant to Section 5.1) and the registration form to
be used may be used for the registration of Registrable Securities (a "Piggyback
Registration"), whether or not for sale for its own account, the Company will
give prompt written notice to the Medicor Group, on behalf of the Medicor
Parties, ERI, on behalf of the ERI Parties, and the Belfer Group, on behalf of
the Belfer Parties, of its intention to effect such a registration and will
include in such registration all Registrable Securities with respect to which
the Company has received written requests for inclusion therein within twenty
(20) days after the receipt of the Company's notice. The Company will use its
reasonable best efforts to include, and to cause the managing underwriters, if
applicable, to include in the proposed offering such Registrable Securities on
the same terms and conditions as the securities of the Company included in such
registration.

                  (b) Priority on Primary Registrations. If a Piggyback
Registration is an underwritten primary registration on behalf of the Company,
and the managing underwriters advise the Company in writing that in their
opinion the number of securities requested to be included in such registration
exceeds the number which can be sold in such offering within a price range
reasonably acceptable to the Company, the Company will include in such
registration (i) first, the securities the Company proposes to sell, to the
extent of availability and, (ii) second, all other securities (including the
Registrable Securities) requested to be included in such registration, pro rata
among the respective holders thereof on the basis of the number of securities
owned by each such holder.

                  (c) Priority on Secondary Registrations. If a Piggyback
Registration is an underwritten secondary registration on behalf of holders of
the Company's securities, and the managing underwriters advise the Company in
writing that in their opinion the number of securities requested to be included
in such registration exceeds the number which can be sold in such offering
within a price range reasonably acceptable to such holders, the securities which
can be included in such registration shall be allocated as follows: (i) first,
the securities (including the Registrable Securities) requested to be included
in such registration by the Persons exercising the Demand Registration, (ii)
then, to the extent of availability, securities to be registered for the account
of the Company and (iii) thereafter, to the extent of availability, to other
security holders



                                      -15-
<PAGE>

exercising piggyback registration rights, pro rata based upon the number of
Shares owned by each such holder.

                  (d) Limited Purpose Shelf Registration Statement. In order to
facilitate the exercise by the Medicor Group, ERI and the Belfer Group of their
Piggyback Registration rights, upon request of either the Medicor Group, ERI or
the Belfer Group (any such request shall not constitute a Demand Registration
for purposes of Section 5.1), the Company shall prepare and file with the
Commission one or more registration statements on Form S-3 under Rule 415 of the
Securities Act providing for the resale of Registrable Securities in an amount
of shares to be mutually agreed by Company and the Medicor Group, ERI and the
Belfer Group from time to time, provided, that such registration statement on
Form S-3 shall be restricted for use by the holders of the securities subject to
such registration statement only for participation pursuant to Section 5.2 in a
firmly underwritten public offering of Common Stock proposed by the Company for
the account of the Company or the account of any other security holder.

         Section 5.3. Holdback Agreements.

                  (a) If requested in writing by the Company or the managing
underwriters, if any, of any registration effected pursuant to Sections 5.1 or
5.2, the Medicor Group agrees not to and will cause the other Medicor Parties
not to, ERI agrees not to and will cause the other ERI Parties not to, and the
Belfer Group agrees not to and will cause the other Belfer Parties not to effect
any public sale or distribution (including sales pursuant to Rule 144) of equity
securities of the Company, or any securities convertible into or exchangeable or
exercisable for such securities, during the time period reasonably requested by
the managing underwriters, not to exceed seven (7) days prior to and the 180-day
period beginning on the effective date of any underwritten Demand Registration,
any underwritten Piggyback Registration or other underwritten registration by
the Company of its securities (except as part of such underwritten
registration).

                  (b) If requested in writing by the managing underwriters of
any registration effected pursuant to Section 5.1 or 5.2, the Company agrees (i)
not to effect any public sale or distribution of its equity securities, or any
securities convertible into or exchangeable or exercisable for such securities,
during the time period reasonably requested by the managing underwriters, not to
exceed seven days prior to and during the 180-day period beginning on the
effective date of any underwritten Demand Registration or any underwritten
Piggyback Registration (except as part of such underwritten registration or
pursuant to registrations on Form S-4 or Form S-8 or any successor forms), and
(ii) to cause each holder of its Common Stock, or any securities convertible
into or exchangeable or exercisable for Common Stock, purchased from the Company
at any time after the date of this Agreement (other than in a registered public
offering), to so agree.

                  (c) If the Company has previously filed a registration
statement with respect to Registrable Securities pursuant to Sections 5.1 or
5.2, and if such previous registration has not been withdrawn or abandoned, the
Company will not file or cause to be effected any other registration of any of
its equity securities or securities convertible or exchangeable into or
exercisable for its equity securities under the Securities Act (except on Form
S-4 or Form S-8 or



                                      -16-
<PAGE>

any successor forms), whether on its own behalf or at the request of any holder
or holders of such securities, until a period of at least ninety (90) days has
elapsed from the effective date of such previous registration.

         Section 5.4. Registration Procedures. Whenever the Medicor Group, on
behalf of the Medicor Parties, ERI, on behalf of the ERI Parties, or the Belfer
Group on behalf of the Belfer Parties has requested that any Registrable
Securities be registered pursuant to this Agreement, the Company will use its
best efforts to effect the registration and the sale of such Registrable
Securities in accordance with the intended method of disposition thereof, and
pursuant thereto the Company will as expeditiously as possible:

                  (a) prepare and file with the Commission a registration
statement with respect to such Registrable Securities and thereafter use its
reasonable best efforts to cause such registration statement to become effective
(provided that, before filing a registration statement or prospectus or any
amendments or supplements thereto, the Company will furnish to the counsel
selected by the holders of the Registrable Securities covered by such
registration statement copies of all such documents proposed to be filed, which
documents will be subject to reasonable review of such counsel);

                  (b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
a period of either (i) not less than six months (subject to extension pursuant
to Section 5.7(b)) or, if such registration statement relates to an underwritten
offering, such longer period as in the opinion of counsel for the underwriters a
prospectus is required by law to be delivered in connection with sales of
Registrable Securities by an underwriter or dealer or (ii) such shorter period
as will terminate when all of the securities covered by such registration
statement have been disposed of in accordance with the intended methods of
disposition by the seller or sellers thereof set forth in such registration
statement (but in any event not before the expiration of any longer period
required under the Securities Act), and to comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such
registration statement until such time as all of such securities have been
disposed of in accordance with the intended methods of disposition by the seller
or sellers thereof set forth in such registration statement;

                  (c) furnish to each seller of Registrable Securities such
number of copies of such registration statement, each amendment and supplement
thereto, the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller;

                  (d) use its best efforts to register or qualify such
Registrable Securities under such other securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this



                                      -17-
<PAGE>

subparagraph, (ii) subject itself to taxation in any such jurisdiction or (iii)
consent to general service of process in any such jurisdiction);

                  (e) notify each seller of such Registrable Securities, at any
time when a prospectus relating thereto is required to be delivered under the
Securities Act, upon discovery that, or upon the discovery of the happening of
any event as a result of which, the prospectus included in such registration
statement contains an untrue statement of a material fact or omits any fact
necessary to make the statements therein not misleading in the light of the
circumstances under which they were made, and, at the request of any such
seller, the Company will prepare and furnish to such seller a reasonable number
of copies of a supplement or amendment to such prospectus so that, as thereafter
delivered to the purchasers of such Registrable Securities, such prospectus will
not contain an untrue statement of a material fact or omit to state any fact
necessary to make the statements therein not misleading in the light of the
circumstances under which they were made;

                  (f) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed and, if not so listed, to be listed on the Nasdaq National Market or the
New York Stock Exchange;

                  (g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

                  (h) enter into such customary agreements (including
underwriting agreements in customary form for similar offerings) and take all
such other actions as the holders of a majority of the Registrable Securities
being sold or the underwriters, if any, reasonably request in order to expedite
or facilitate the disposition of such Registrable Securities (including, without
limitation, effecting a stock split or a combination of shares);

                  (i) make available for inspection by any seller of Registrable
Securities, any underwriter participating in any disposition pursuant to such
registration statement, and any attorney, accountant or other agent retained by
any such seller or underwriter, all financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers, Directors, employees and independent accountants to supply all
information reasonably requested by any such seller, underwriter, attorney,
accountant or agent in connection with such registration statement;

                  (j) otherwise use its reasonable best efforts to comply with
all applicable rules and regulations of the Commission, and make available to
its security holders, as soon as reasonably practicable, an earnings statement
covering the period of at least twelve months beginning with the first day of
the Company's first full calendar quarter after the effective date of the
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 thereunder;

                  (k) in the event of the issuance of any stop order, injunction
or other order or requirement suspending the effectiveness of a registration
statement, or of any order suspending or preventing the use of any related
prospectus or suspending the qualification of any securities



                                      -18-
<PAGE>

included in such registration statement for sale in any jurisdiction, the
Company will use its reasonable best efforts promptly to obtain the withdrawal
of such order and to notify the holders of all of the Registrable Securities
covered by the registration statement of such order;

                  (l) obtain a cold comfort letter, dated the effective date of
such registration statement (and, if such registration includes an underwritten
public offering, dated the date of the closing under the underwriting
agreement), signed by the Company's independent public accountants in customary
form and covering such matters of the type customarily covered by cold comfort
letters as the holders of a majority of the Registrable Securities being sold
reasonably request (provided that such Registrable Securities constitute at
least 10% of the securities covered by such registration statement);

                  (m) provide a legal opinion of the Company's outside counsel,
dated the effective date of such registration statement (and, if such
registration includes an underwritten public offering, dated the date of the
closing under the underwriting agreement), with respect to the registration
statement, each amendment and supplement thereto, the prospectus included herein
(including the preliminary prospectus) and such other documents relating thereto
in customary form and covering such matters of the type customarily covered by
legal opinions of such nature;

                  (n) promptly furnish to the managing underwriter, if any, and
each seller of Registrable Securities copies of any written request by the
Commission or any state securities authority for amendments or supplements to a
registration statement or prospectus or for additional information; and

                  (o) make reasonably available its employees and personnel and
otherwise provide reasonable assistance to any underwriters in the marketing of
Registrable Securities in any underwritten offering.

         The Company may require each seller of Registrable Securities as to
which any registration is being effected to furnish the Company such information
regarding such seller and the distribution of such securities as the Company may
from time to time reasonably request in writing.

         Section 5.5. Registration Expenses.

                  (a) The Company shall pay all Registration Expenses relating
to any registration of Registrable Securities hereunder. "Registration Expenses"
shall mean any and all fees and expenses incident to the Company's performance
of or compliance with this Article V, including, without limitation: (i)
Commission, stock exchange or National Association of Securities Dealers, Inc.
registration and filing fees and all listing fees and fees with respect to the
inclusion of securities on the Nasdaq National Market, (ii) fees and expenses of
compliance with state securities or "blue sky" laws and in connection with the
preparation of a "blue sky" survey, including, without limitation, reasonable
fees and expenses of blue sky counsel, (iii) printing expenses, (iv) messenger
and delivery expenses, (v) fees and disbursements of counsel for the Company,
(vi) with respect to each registration, reasonable fees and disbursements of one



                                      -19-
<PAGE>

counsel for the selling holders of Shares (selected by the holders making the
Demand Registration request, in the case of a registration pursuant to Section
5.1, and selected by the holders of a majority of the Registrable Securities
included in such registration, in the case of a registration pursuant to Section
5.2) as well as of one local counsel, (vii) fees and disbursements of all
independent public accountants (including the expenses of any audit and/or "cold
comfort" letter) and fees and expenses of other persons, including special
experts, retained by the Company, and (viii) any other fees and disbursements of
underwriters, if any, customarily paid by issuers or sellers of securities.

                  (b) Notwithstanding the foregoing, (i) the provisions of this
Section 5.5 shall be deemed amended to the extent necessary to cause these
expense provisions to comply with "blue sky" laws of each state in which the
offering is made and (ii) in connection with any registration hereunder, each
holder of Registrable Securities being registered shall pay all underwriting
discounts and commissions and transfer taxes, if any, attributable to the
Registrable Securities included in the offering by such holder.

         Section 5.6. Indemnification.

                  (a) The Company agrees to indemnify and hold harmless, to the
extent permitted by law, each holder of Registrable Securities, its officers and
Directors and each Person who controls such holder (within the meaning of the
Securities Act) against any losses, claims, damages, liabilities, joint or
several, to which such holder or any such Director or officer or controlling
person may become subject under the Securities Act or otherwise, insofar as such
losses, claims, damages or liabilities (or actions or proceedings, whether
commenced or threatened, in respect thereof) arise out of or are based upon (i)
any untrue or alleged untrue statement of a material fact contained (A) in any
registration statement, prospectus or preliminary prospectus or any amendment
thereof or supplement thereto or (B) in any application or other document or
communication (in this Section 5.6 collectively called an "application")
executed by or on behalf of the Company or based upon written information
furnished by or on behalf of the Company filed in any jurisdiction in order to
qualify any securities covered by such registration statement under the "blue
sky" or securities laws thereof, or (ii) any omission or alleged omission of a
material fact required to be stated therein or necessary to make the statements
therein not misleading, and the Company will reimburse such holder and each such
Director, officer and controlling person for any legal or any other expenses
incurred by them in connection with investigating or defending any such loss,
claim, liability, action or proceeding; provided that the Company shall not be
liable in any such case to the extent that any such loss, claim, damage,
liability (or action or proceeding in respect thereof) or expense arises out of
or is based upon an untrue statement or alleged untrue statement, or omission or
alleged omission, made in such registration statement, any such prospectus or
preliminary prospectus or any amendment or supplement thereto, or in any
application, in reliance upon and in conformity with written information
prepared and furnished to the Company by such holder expressly for use therein
or by such holder's failure to deliver a copy of the registration statement or
prospectus or any amendments or supplements thereto after the Company has
furnished such holder with a sufficient number of copies of the same. In
connection with an underwritten offering, the Company will indemnify such
underwriters, their officers and Directors and each Person who



                                      -20-
<PAGE>

controls such underwriters (within the meaning of the Securities Act) to the
same extent as provided above with respect to the indemnification of the holders
of Registrable Securities.

                  (b) In connection with any registration statement in which a
holder of Registrable Securities is participating, each such holder will furnish
to the Company in writing such information and documents as the Company
reasonably requests for use in connection with any such registration statement
or prospectus and, to the extent permitted by law, will indemnify and hold
harmless the Company, its Directors and officers and each other Person who
controls the Company (within the meaning of the Securities Act) against any
losses, claims, damages, liabilities, joint or several, to which the Company or
any such Director or officer or controlling person may become subject under the
Securities Act or otherwise, insofar as such losses, claims, damages or
liabilities (or actions or proceedings, whether commenced or threatened, in
respect thereof) arise out of or are based upon (i) any untrue or alleged untrue
statement of a material fact contained in the registration statement, prospectus
or preliminary prospectus or any amendment thereof or supplement thereto or in
any application or (ii) any omission or alleged omission of a material fact
required to be stated therein or necessary to make the statements therein not
misleading, but only to the extent that such untrue statement or omission is
made in such registration statement, any such prospectus or preliminary
prospectus or any amendment or supplement thereto, or in any application, in
reliance upon and in conformity with written information prepared and furnished
to the Company by such holder expressly for use therein, and such holder will
reimburse the Company and each such Director, officer and controlling person for
any legal or any other expenses incurred by them in connection with
investigating or defending any such loss, claim, liability, action or
proceeding; provided that the obligation to indemnify will be individual to each
holder and will be limited to the net amount of proceeds received by such holder
from the sale of Registrable Securities pursuant to such registration statement.

                  (c) Any Person entitled to indemnification hereunder will (i)
give prompt written notice to the indemnifying party of any claim with respect
to which it seeks indemnification and (ii) unless in such indemnified party's
reasonable judgment a conflict of interest between such indemnified and
indemnifying parties may exist with respect to such claim, permit such
indemnifying party to assume the defense of such claim with counsel reasonably
satisfactory to the indemnified party. If such defense is assumed, the
indemnifying party will not be subject to any liability for any settlement made
by the indemnified party without its consent (but such consent will not be
unreasonably withheld). An indemnifying party who is not entitled to, or elects
not to, assume the defense of a claim will not be obligated to pay the fees and
expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the reasonable judgment
of any indemnified party a conflict of interest may exist between such
indemnified party and any other of such indemnified parties with respect to such
claim.

                  (d) The indemnification provided for under this Agreement will
remain in full force and effect regardless of any investigation made by or on
behalf of the indemnified party or any officer, Director or controlling Person
of such indemnified party and will survive the transfer of securities by any
holder thereof. The Company also agrees to make such provisions, as are



                                      -21-
<PAGE>

reasonably requested by any indemnified party, for contribution to such party in
the event the Company's indemnification is unavailable for any reason.

         Section 5.7. Participation in Underwritten Registrations.

                  (a) If requested by the underwriters for any underwritten
offering pursuant to a Demand Registration requested under Section 5.1, the
Company shall enter into a customary underwriting agreement with the
underwriters. Such underwriting agreement shall be satisfactory in form and
substance to the Person who requested such registration and shall contain such
representations and warranties by, and such other agreements on the part of, the
Company and such other terms as are generally prevailing in agreements of that
type, including, without limitation, indemnities and contribution agreements.
Such underwriting agreement shall also contain such representations, warranties,
indemnities and contributions by the participating holders as are customary in
agreements of that type. In the case of a registration pursuant to Section 5.2
hereof, if the Company shall have determined to enter into any underwriting
agreements in connection therewith, all of the holders' Registrable Securities
to be included in such registration shall be subject to such underwriting
agreement. Such underwriting agreement shall also contain such representations,
warranties, indemnities and contributions by the participating holders as are
customary in agreements of that type.

                  (b) Each Person that is participating in any registration
hereunder agrees that, upon receipt of any notice from the Company of the
happening of any event of the kind described in Section 5.4(e) above, such
Person will forthwith discontinue the disposition of its Registrable Securities
pursuant to the registration statement until such Person's receipt of the copies
of a supplemented or amended prospectus as contemplated by such Section 5.4(e).
In the event the Company shall give any such notice, the applicable time period
mentioned in Section 5.4(b) during which a registration statement is to remain
effective shall be extended by the number of days during the period from and
including the date of the giving of such notice pursuant to this paragraph to
and including the date when each seller of a Registrable Security covered by
such registration statement shall have received the copies of the supplemented
or amended prospectus contemplated by Section 5.4(e).

         Section 5.8. Current Public Information. At all times after the Company
has filed a registration statement with the Commission pursuant to the
requirements of either the Securities Act or the Exchange Act, the Company will
file all reports required to be filed by it under the Act and the Exchange Act
and the rules and regulations adopted by the Commission thereunder, and will
take such further action as any holder or holders of Registrable Securities may
reasonably request, all to the extent required to enable such holders to sell
Registrable Securities pursuant to Rule 144.

         Section 5.9. Cooperation. If the Company determines to authorize and/or
issue any capital stock or other debt or equity securities in a public offering,
each of the Parties and their Permitted Transferees agrees to cooperate with the
Company and to take all action necessary to assist the Company in consummating
such transaction.



                                      -22-
<PAGE>

                                   ARTICLE VI
                               GENERAL PROVISIONS

         Section 6.1. Notices. Any notice required to be given hereunder shall
be sufficient if in writing, and sent by facsimile transmission and by courier
service (with proof of service), hand delivery or certified or registered mail
(return receipt requested and first-class postage prepaid), addressed as
follows:

                  If to the Belfer Group:

                           Robert A. Belfer
                           767 Fifth Avenue, 46th Floor
                           New York, New York 10153
                           Fax Number:  (212) 644-2300
                           Phone Number: (212) 644-2200

                  With a copy to:

                           Vinson & Elkins L.L.P.
                           666 Fifth Avenue, 26th Floor
                           New York, New York  10103-0400
                           Attention:  Alan P. Baden
                           Fax Number:  (917) 206-8100
                           Phone Number: (917) 206-8001

                  If to Westport or the Company:

                           Donald D. Wolf,
                           Chairman and Chief Executive Officer
                           1670 Broadway, Suite 2800
                           Denver, CO.  80202
                           Fax Number:  (303) 573-5609
                           Phone Number: (303) 573-5404



                                      -23-
<PAGE>

                  If to Westport Energy LLC:

                           Westport Energy LLC
                           c/o Westport Investments Limited
                           Lyford Manor
                           Lyford Cay
                           P.O. Box N-7776
                           Nassau, Bahamas
                           Fax Number: (242) 362-5788

                  With a copy to:

                           Akin Gump Strauss Hauer & Feld LLP
                           1700 Pacific Avenue, Suite 4100
                           Dallas, Texas  75201-4675
                           Attention:  Michael E. Dillard, P.C.
                           Fax Number:  (214) 969-4343
                           Phone Number: (214)  969-2800

                  And to:

                           Michael Russell
                           Dr. Richard J. Haas Partners
                           Dukes Court
                           32 Duke Street, St. James's
                           London, SW1Y 6DF
                           Fax Number:  020.7.321.5242
                           Phone Number: 020.7.321.5200

                  If to ERI Investments, Inc.:

                           Johanna G. O'Loughlin
                           Vice President, General Counsel and Secretary
                           ERI Investments, Inc.
                           One Oxford Centre, Suite 3300
                           Pittsburgh, PA  15219
                           Telephone: (412) 553-7760
                           Telecopy: (412) 553-5970



                                      -24-
<PAGE>

                  With a copy to:

                           Stephen W. Johnson, Esquire
                           Reed Smith LLP
                           435 Sixth Avenue
                           Pittsburgh, PA  15219-1886
                           Telephone: (412) 288-3131
                           Telecopy: (412) 288-3053

                  If to the Medicor Group:

                           Medicor Foundation
                           c/o Jura Trust AG
                           Mitteldorf 1
                           Postfach 838
                           FL-9490 Vaduz, Liechtenstein

                  With a copy to:

                           Kenneth S. Witt
                           Greenberg Traurig, LLP
                           1200 17th Street, Suite 2400
                           Denver, CO  80202
                           Telephone: (303) 572-6510
                           Telecopy: (303) 572-6540

or to such other address as any party shall specify by written notice so given,
and such notice shall be deemed to have been delivered as of the date so
telecommunicated, personally delivered or mailed.

         Section 6.2. Assignment; Binding Effect; Benefit. Any Party that
Transfers to a Permitted Transferee shall promptly give written notice of such
Transfer to the Parties pursuant to Section 6.1 and shall deliver to such
Parties a copy of the written agreement pursuant to which the Permitted
Transferee has agreed to be bound by the terms of this Agreement. Other than
Transfers to Permitted Transferees, neither this Agreement nor any of the
rights, interests or obligations hereunder shall be assigned by any of the
Parties or their Permitted Transferees without the prior written consent of the
other Parties; provided, that the Medicor Parties, the ERI Parties and the
Belfer Parties may assign all or a portion of their rights under Article V in
connection with any Transfer of Registrable Securities made in accordance with
this Agreement if immediately after the Transfer, the transferee beneficially
owns at least ten percent (10%) of the Common Stock of the Company then
outstanding, in which event each transferee will have rights and obligations
under Article V as if it was a party to this Agreement to the extent of such
assignment. Subject to the preceding sentence, this Agreement shall be binding
upon and shall inure to the benefit of the parties hereto and their respective
successors and assigns. Notwithstanding anything contained in this Agreement to
the contrary, nothing in this Agreement, express or implied, is intended to
confer on any person other than the parties hereto



                                      -25-
<PAGE>

or their respective heirs, successors, executors, administrators and assigns any
rights, remedies, obligations or liabilities under or by reason of this
Agreement.

         Section 6.3. Entire Agreement. The Merger Agreement, this Agreement,
the exhibits and schedules hereto and any certificate delivered by the parties
in connection herewith constitute the entire agreement among the parties with
respect to the subject matter hereof and supersede all prior agreements and
understandings (oral and written) among the parties with respect thereto.

         Section 6.4. Amendment. No amendment, modification or waiver of this
Agreement shall be effective against any Party unless it shall be in writing and
signed by such Party. Notwithstanding the foregoing, Exhibit A shall be amended
or modified from time to time to reflect Transfers to Permitted Transferees by
giving written notice of such Transfers to the Parties pursuant to Section 6.1.

         Section 6.5. Governing Law; Jurisdiction. This Agreement shall be
governed by and construed in accordance with the laws of the State of Nevada
without regard to its rules of conflict of laws. The Parties agree that any
suit, action or proceeding arising out of, or with respect to, this Agreement or
any judgment entered by any court in respect thereof may be brought only in the
courts of the State of Nevada or the federal district courts located within the
State of Nevada and the Parties hereby accept the exclusive jurisdiction of
those courts for the purpose of any suit, action or proceeding.

         Section 6.6. Counterparts. This Agreement may be executed by the
parties hereto in separate counterparts, each of which when so executed and
delivered shall be an original, but all such counterparts shall together
constitute one and the same instrument. Each counterpart may consist of a number
of copies of this Agreement, each of which may be signed by less than all of the
parties hereto, but together all such copies are signed by all of the parties
hereto.

         Section 6.7. Headings. Headings of the Articles and Sections of this
Agreement are for the convenience of the parties only and shall be given no
substantive or interpretive effect whatsoever.

         Section 6.8. Interpretation. In this Agreement, unless the context
otherwise requires: (i) words describing the singular number shall include the
plural and vice versa; (ii) "including" shall mean including, without
limitation; (iii) words denoting any gender shall include all genders; and (iv)
words denoting natural persons shall include corporations and partnerships and
vice versa.

         Section 6.9. Incorporation of Exhibits and Schedules. All exhibits and
schedules hereto are hereby incorporated herein and made a part hereof for all
purposes as if fully set forth herein.

         Section 6.10. Severability. Any term or provision of this Agreement
which is invalid or unenforceable in any jurisdiction shall, as to that
jurisdiction, be ineffective to the extent of such invalidity or
unenforceability without rendering invalid or unenforceable the remaining terms
and provisions of this Agreement or otherwise affecting the validity or
enforceability of any of the



                                      -26-
<PAGE>

terms or provisions of this Agreement in any other jurisdiction. If any
provision of this Agreement is so broad as to be unenforceable, the provision
shall be interpreted to be only so broad as is enforceable.

         Section 6.11. Enforcement of Agreement. The Parties hereto agree that
irreparable damage would occur in the event that any of the provisions of this
Agreement were not performed in accordance with its specific terms or was
otherwise breached. It is accordingly agreed that the Parties and their
Permitted Transferees shall be entitled to an injunction or injunctions to
prevent breaches of this Agreement and to enforce specifically the terms and
provisions hereof in any court, this being in addition to any other remedy to
which they may be entitled at law or in equity.

         Section 6.12. Confidentiality. None of the Medicor Group, their
Affiliates, employees, agents or representatives, ERI, its Affiliates,
employees, agents or representatives nor the Belfer Group, their Affiliates,
agents or representatives shall disclose to any third party any information
obtained about the Company or its operations or business which it may have
acquired pursuant to this Agreement, the Original Shareholders Agreement, the
Amended Shareholders Agreement or the Second Amended and Restated Shareholders
Agreement without the prior written consent of the Company; provided, that any
information that is otherwise publicly available, without breach of this
provision, or has been obtained from a third party without a breach of such
third party's duties, shall not be deemed confidential information.

         Section 6.13. Termination. This Agreement shall terminate and shall
cease to be binding on the Parties upon the earliest to occur of:

                  (a) with respect to any Party and its Permitted Transferees,
the date on which such Party and its Permitted Transferees cease to own at least
5.0% of the outstanding Common Stock; and

                  (b) with respect to any Party and its Permitted Transferees,
the date on which such Party and its Permitted Transferees cease to own at least
25% of the Common Stock owned by them as of the Effective Time; and

                  (c) the date on which all of the Parties who are then bound
hereby mutually consent to terminate this Agreement in writing;

provided, however, notwithstanding the provisions of Section 6.13 (a), (b) and
(c) above, the provisions of Article V shall continue in effect with respect to
a Party and its Permitted Transferees as long as it holds Registrable Securities
and the provisions of Section 6.12 shall not terminate.

         Section 6.14. Belfer Group Representative. Robert A. Belfer shall be
the initial Belfer Group representative (the "Belfer Group Representative"). The
Belfer Group Representative may be changed by delivery of a written notification
delivered to the parties hereto and executed by all of the members of the Belfer
Group. Each member of the Belfer Group hereby appoints the person or entity who
is, from time to time, duly appointed under this Section 6.14 as the



                                      -27-
<PAGE>

Belfer Group Representative to give any consent or approval, exercise any right
or take any action contemplated under this Agreement on behalf of the Belfer
Group. The members of the Belfer Group shall be so bound by the Belfer Group
Representative and the parties to this Agreement shall be entitled to rely on
the actions taken by the Belfer Group Representative contemplated by this
Agreement.

         Section 6.15. Medicor Group Representative. Michael Russell shall be
the initial Medicor Group representative (the "Medicor Group Representative").
The Medicor Group Representative may be changed by delivery of a written
notification delivered to the parties hereto and executed by all of the members
of the Medicor Group. Each member of the Medicor Group hereby appoints the
person or entity who is, from time to time, duly appointed under this Section
6.15 as the Medicor Group Representative to give any consent or approval,
exercise any right or take any action contemplated under this Agreement on
behalf of the Medicor Group. The members of the Medicor Group shall be so bound
by the Medicor Group Representative and the parties to this Agreement shall be
entitled to rely on the actions taken by the Medicor Group Representative
contemplated by this Agreement. The inclusion of WELLC and Medicor in a group,
referenced in this Agreement as the Medicor Group, and the appointment by WELLC
and Medicor of a Medicor Group Representative, as set forth above in this
Section 6.15, are merely for administrative convenience. Each of Medicor and
WELLC is a distinct legal entity, and neither Medicor nor WELLC controls the
other or is under the common control of a third party.

         Section 6.16. Effective Time. Notwithstanding anything herein to the
contrary, this Agreement shall become effective upon the transfer by WELLC of
not less than nine million of its shares of Common Stock to Medicor (the
"Effective Time"). The representations and warranties contained herein shall be
deemed to have been made as of the Effective Time. If the above mentioned
transfer by WELLC to Medicor does not occur on or before April 15, 2003 for any
reason, this Agreement shall terminate and the Second Amended and Restated
Shareholders Agreement shall remain in effect.



                                      -28-

<PAGE>


         IN WITNESS WHEREOF, the parties have executed this Third Amended and
Restated Shareholders Agreement and caused the same to be duly delivered on
their behalf as of the day and year first written above, to be effective as of
the Effective Date.

                             WESTPORT RESOURCES CORPORATION:


                             By:    /s/ BARTH E. WHITHAM
                             Name:  Barth E. Whitham
                             Title: President and Chief Operating Officer



                             WESTPORT ENERGY LLC:

                             By: WESTPORT INVESTMENTS LIMITED, its
                             Managing Member

                                 By:    /s/ ROBERT A. HAAS
                                 Name:  Robert A. Haas
                                 Title: Vice President



                             ERI INVESTMENTS, INC.:


                             By:    /s/ KENNETH J. KUBACKI
                             Name:  Kenneth J. Kubacki
                             Title: Vice President



                             MEDICOR FOUNDATION:


                             By:    /s/ MICHAEL RUSSELL
                             Name:  Michael Russell
                             Title: Member of Counsel

                             By:    /s/ URSULA HAAS
                             Name:  Ursula Haas
                             Title: President


                             /s/ ROBERT A. BELFER
                             ------------------------------------------------
                             ROBERT A. BELFER




<PAGE>

                             /s/ JACK SALTZ
                             ------------------------------------------------
                             JACK SALTZ


                             SALTZ INVESTMENT GROUP, LLC:


                             By:    /s/ JACK SALTZ
                                --------------------------------------------
                             Name:  Jack Saltz
                             Title: Manager and Member


                             JACK & ANITA SALTZ FOUNDATION:


                             By:    /s/ JACK SALTZ
                                --------------------------------------------
                             Name:  Jack Saltz
                             Title: President


                             THE ROBERT A. AND RENEE E. BELFER FAMILY
                             FOUNDATION:


                             By:    /s/ ROBERT A. BELFER
                                --------------------------------------------
                             Name:  Robert A. Belfer
                             Title: Trustee and Donor


                             BELFER CORP.:


                             By:    /s/ ROBERT A. BELFER
                                --------------------------------------------
                             Name:  Robert A. Belfer
                             Title: President




<PAGE>


                             BELWEST PETROLEUM, INC.:


                             By:    /s/ ROBERT A. BELFER
                                --------------------------------------------
                             Name:  Robert A. Belfer
                             Title: President


                             A&B INVESTORS, INC.:


                             By:    /s/ ROBERT A. BELFER
                                --------------------------------------------
                             Name:  Robert A. Belfer
                             Title:


                             RENEE HOLDINGS PARTNERSHIP, L.P.:


                             By:    /s/ ROBERT A. BELFER
                                --------------------------------------------
                             Name:  Robert A. Belfer
                             Title: General Partner


                             THE LAURENCE D. BELFER FAMILY FOUNDATION:


                             By:    /s/ LAURENCE D. BELFER
                                --------------------------------------------
                             Name:  Laurence D. Belfer
                             Title: Trustee and Donor




<PAGE>

                             LDB CORP.:


                             By:    /s/ LAURENCE D. BELFER
                                --------------------------------------------
                             Name:  Laurence D. Belfer
                             Title: President


                             ROBERT A. BELFER 1990 FAMILY TRUST:


                             By:    /s/ LAURENCE D. BELFER
                                --------------------------------------------
                             Name:  Laurence D. Belfer
                             Title: Trustee


                             VANTZ LIMITED PARTNERSHIP:

                             By: VANTZ LLC
                                 Its General Partner

                                 By:    /s/ LAURENCE D. BELFER
                                    ---------------------------------------
                                 Name:  Laurence D. Belfer
                                 Title:


                             LDB TWO CORP.:


                             By:    /s/ LAURENCE D. BELFER
                             Name:  Laurence D. Belfer
                             Title: President



<PAGE>


                             BELFER TWO CORP.:


                             By:    /s/ ROBERT A. BELFER
                             Name:  Robert A. Belfer
                             Title: President


                             LIZ PARTNERS, L.P.

                             By: Liz Associates LLC,
                                 Its General Partner

                                 By:    /s/ ROBERT A. BELFER
                                 Name:  Robert A. Belfer
                                 Title: Managing Member of Liz Associates LLC




<PAGE>


                                    EXHIBIT A

                              CERTAIN STOCKHOLDERS


Jack Saltz
Saltz Investment Group, LLC
Jack & Anita Saltz Foundation
The Robert A. and Renee E. Belfer Family Foundation,
Robert A. Belfer
Belfer Corp.
Belwest Petroleum, Inc.
A&B Investors, Inc.
Renee Holdings Partnership, L.P.
The Laurence D. Belfer Family Foundation
LDB Corp.
Robert A. Belfer 1990 Family Trust
Vantz Limited Partnership
LDB Two Corp. (a Permitted Transferee of the Shares previously held by Laurence
  D. Belfer)
Belfer Two Corp. (a Permitted Transferee of the Shares previously held by Renee
  E. Belfer)
Liz Partners, L.P. (a Permitted Transferee of the Shares previously held by
  Elizabeth K. Belfer, which includes Shares distributed pursuant to the
  expiration of the two trusts for the benefit of Elizabeth K. Belfer (T6 and
  T7))



<PAGE>


                                  SCHEDULE 2.2

                         OWNERSHIP - EACH MEDICOR PERSON


<Table>
<Caption>
                                                         Ownership of Common Stock
                      Stockholder                          as of the date hereof
                 ------------------------                -------------------------
<S>                                                      <C>
                   Medicor Foundation                             11,000,000
                   Westport Energy LLC                             3,238,001
</Table>




<PAGE>


                                  SCHEDULE 2.3

                            OWNERSHIP -- ERI PARTIES



<Table>
<Caption>
                                                         Ownership of Common Stock
                       Stockholder                        as of the date hereof
                 ------------------------                -------------------------
<S>                                                      <C>
                  ERI Investments, Inc.                           13,911,152
</Table>




<PAGE>


                                  SCHEDULE 2.4

                         OWNERSHIP - EACH BELFER PERSON


<Table>
<Caption>
                        Stockholder                                      Shares held as of the date hereof
                        -----------                                      ---------------------------------
<S>                                                                      <C>
Jack Saltz                                                                             6,187
Saltz Investment Group, LLC(1)                                                        776,829
Jack & Anita Saltz Foundation(1)                                                      62,039
The Robert A. and Renee E. Belfer Family Foundation(2)                                263,793
Robert A. Belfer                                                                        --
Belfer Corp. (2)                                                                     2,753,270
Belwest Petroleum, Inc. (2)                                                             136
A&B Investors, Inc. (2)                                                                 --
Renee Holdings Partnership, L.P. (2)                                                  492,283
The Laurence D. Belfer Family Foundation(3)                                            5,077
LDB Corp. (3)                                                                         112,552
Robert A. Belfer 1990 Family Trust(3)                                                 230,040
Vantz Limited Partnership (3)                                                         261,610
LDB Two Corp. (3)                                                                     823,031
Belfer Two Corp. (2)                                                                 1,157,309
Liz Partners, L.P. (2)                                                                495,899
</Table>

-----------

(1)      c/o Jack Saltz, 767 Fifth Floor Avenue, 46th Floor, New York, New York
         10153

(2)      c/o Robert A. Belfer, 767 Fifth Avenue, 46th Floor, New York, New York
         10153

(3)      c/o Laurence D. Belfer, 767 Fifth Avenue, 46th Floor, New York, New
         York 10153