Document:

<PAGE>

                                                                    Exhibit 4.14
                                                                    ------------

                               AMENDMENT NO. 1 TO
                          REGISTRATION RIGHTS AGREEMENT

            AMENDMENT NO. 1 TO REGISTRATION RIGHTS AGREEMENT (this "Amendment")
                                                                    ---------
dated as of November 1, 2001 by and among Concentra Inc., a Delaware corporation
formerly known as Concentra Managed Care, Inc. (the "Company"), the several
                                                     -------
persons signatory hereto and named on Schedule I hereto under the heading
"Schedule I Purchasers" and the several persons signatory hereto and named on
Schedule II hereto under the heading "FFT Purchasers". Capitalized terms used in
this Amendment which are not otherwise defined herein shall have the meanings
ascribed to them in the Registration Rights Agreement referred to below.

                              W I T N E S S E T H:
                              --------------------

            WHEREAS, the Company, the several persons named on Schedule I hereto
under the heading "Schedule I Purchasers" (the "Schedule I Purchasers") and the
                   ---------------------        ---------------------
several persons named on Schedule II hereto under the heading "FFT Purchasers"
(the "FFT Purchasers" and, together with the Schedule I Purchasers,
      --------------
collectively, the "Purchasers") are parties to a Registration Rights Agreement
                   ----------
dated as of August 17, 1999 (the "Registration Rights Agreement");
                                  -----------------------------

            WHEREAS, the Company proposes to issue (1) an aggregate 2,266,546
shares of Company Common Stock (the "New Common Shares") and (2) warrants to
                                     -----------------
acquire an aggregate 771,277 shares of Company Common Stock (the "New Warrants"
                                                                  ------------
and, together with the New Common Shares, the "New Securities") pursuant to the
                                               --------------
terms and conditions of a Securities Purchase Agreement (the "Securities
                                                              ----------
Purchase Agreement") dated as of the date hereof among the Company and the
------------------
purchasers named therein (the "Purchasing Stockholders");
                               -----------------------

            WHEREAS, upon the issuance of the New Securities, each Purchaser
will own the number of shares of Company Common Stock, Company Class A Common
Stock and/or New Warrants, as the case may be, appearing opposite the name of
such Purchaser on Schedule I or Schedule II hereto, as the case may be;

            WHEREAS, it is a condition to the respective obligations of the
Company and the Purchasing Stockholders under the Securities Purchase Agreement
that this Amendment be executed and delivered by the Company and each of the
Purchasing Stockholders, including (i) the holders of a majority in interest of
the Restricted Stock currently held by the Schedule I Purchasers and (ii) the
holders of a majority in interest of the Restricted Stock currently held by the
FFT Purchasers;

            WHEREAS, the parties hereto desire to execute and deliver this
Amendment in order to fulfill such condition and to provide for certain
registration matters relating to the New

<PAGE>

Common Shares and the shares of Company Common Stock issuable upon exercise of
the New Warrants (the "Warrant Shares");
                       --------------

            NOW, THEREFORE, in consideration of the premises and of the mutual
covenants and agreements herein contained, the parties hereto hereby agree as
follows:

            SECTION 1. Amendments to Registration Rights Agreement. The
                       -------------------------------------------
Registration Rights Agreement is amended as follows:

            (a) Section 1 of the Registration Rights Agreement is amended to
      insert in the appropriate alphabetical order the following new
      definitions:

            " 'New Common Shares' shall have the meaning provided in Amendment
               --------------
            No. 1 to this Agreement dated as of November 1, 2001."

            " 'Warrant Shares' shall have the meaning provided in Amendment No.
               --------------
            1 to this Agreement dated as of November 1, 2001."

            (b) The definition of Restricted Stock appearing in Section 1 of the
      Registration Rights Agreement is deleted in its entirety and replaced with
      the following new definition:

            " 'Restricted Stock' shall mean any shares of Company Capital Stock,
               ----------------
            the certificates for which are required to bear the legend set forth
            in Section 2 hereof (including, without limitation, all of the New
            Common Shares and any and all Warrant Shares from time to time
            outstanding) held by any party to this Agreement."

            (c) Section 3 of the Registration Rights Agreement is amended to
insert the text "as amended," immediately after the text "Stockholders
Agreement, dated as of the date hereof among the Company and the Purchasers,"
appearing in the first sentence thereof.

            (d) Schedule I to the Registration Rights Agreement is deleted in
its entirety and replaced by Schedule I to this Amendment.

            (e) Schedule II to the Registration Rights Agreement is deleted in
its entirety and replaced by Schedule II to this Amendment.

            SECTION 2. Miscellaneous.
                       -------------

            (a) This Amendment shall be governed by and construed in accordance
      with the laws of the State of New York.

                                       2

<PAGE>

            (b) This Amendment may be executed in two or more counterparts, each
      of which shall be deemed an original, but all of which together shall
      constitute one and the same instrument.

            (c) Headings and section reference numbers in this Amendment are for
      reference purposes only and shall not in any way affect the meaning or
      interpretation of this Amendment.

            (d) This Amendment is limited precisely as written and shall not be
      deemed to be a modification, acceptance or waiver of any other term,
      condition or provision of the Registration Rights Agreement.

                            [signature pages follow]

                                       3

<PAGE>

            IN WITNESS WHEREOF, each of the parties hereto has executed this
Amendment No. 1 to Registration Rights Agreement, all as of the day and year
first above written.

                                     CONCENTRA INC.

                                     By_______________________________________
                                       Name:  Richard A. Parr II
                                       Title: Executive Vice President,
                                              General Counsel and Secretary

                                       _________________________________________
                                       Name:

                                        4

<PAGE>

                                WELSH, CARSON, ANDERSON & STOWE
                                       VIII, L.P.
                                     By:  WCAS VIII Associates, L.L.C.,
                                          General Partner

                                     By:________________________________________
                                          Managing Member

                                     WCAS HEALTHCARE PARTNERS, L.P.
                                     By:  WCAS HC Partners, General Partner

                                     By:________________________________________
                                          General Partner

                                     Patrick J. Welsh
                                     Russell L. Carson
                                     Bruce K. Anderson
                                     Andrew M. Paul
                                     Thomas E. McInerney
                                     Robert A. Minicucci
                                     Anthony J. deNicola
                                     Paul B. Queally
                                     Lawrence B. Sorrel
                                     D. Scott Mackesy
                                     Priscilla A. Newman
                                     Laura M. VanBuren
                                     Sean M. Traynor
                                     John Almedia, Jr.
                                     Jonathan M. Rather

                                     By:________________________________________
                                          Jonathan M. Rather, Individually and
                                          as Attorney-in-Fact

                                       5

<PAGE>

                                          WCAS MANAGEMENT CORP.

                                          By:___________________________________
                                                Name:
                                                Title:

                                          J.P. MORGAN DIRECT CORPORATE FINANCE
                                            INSTITUTIONAL INVESTORS LLC

                                               By:______________________________
                                                    Name:
                                                    Title:

                                          J.P. MORGAN DIRECT CORPORATE FINANCE
                                                 PRIVATE INVESTORS LLC

                                               By:______________________________
                                                    Name:
                                                    Title:

                                          522 FIFTH AVENUE FUND, L.P.

                                               By:______________________________
                                                    Name:
                                                    Title:

                                         CALIFORNIA PUBLIC EMPLOYEES' RETIREMENT
                                           SYSTEM

                                         By:____________________________________
                                              Name:
                                              Title:

                                         CALIFORNIA STATE TEACHERS' RETIREMENT
                                         SYSTEM

                                         By:____________________________________
                                              Name:
                                              Title:

                                        6

<PAGE>

                           CMS CO-INVESTMENT SUBPARTNERSHIP II
                           By: CMS CO-INVESTMENT SUBPARTNERSHIP,
                               a Delaware general partnership
                               By: CMS Co-Investment Partners, L.P.,
                                   a Delaware limited partnership
                                   By: CMS/Co-Investment Associates, L.P.,
                                       a Delaware limited partnership
                                       By: MSPS/Co-Investment, Inc.,
                                           a Delaware corporation

                                       By:_____________________
                                       Its:

                                       By: CMS 1997 Investment Partners, L.P.,
                                           a Delaware limited partnership
                                           By: CMS 1997, Inc., a Delaware
                                               corporation

                                              By:__________________
                                                    Its:

                               By: CMS Co-Investment Partners I-Q, L.P.,
                                  a Delaware limited partnership
                                  By: CMS/Co-Investment Associates,
                                      L.P., a Delaware limited partnership
                                      By: MSPS/Co-Investment, Inc.
                                         a Delaware corporation

                                       By:____________________
                                       Its:

                               By: CMS 1997 Investment Partners, L.P.,
                                   a Delaware limited partnership
                                   By: CMS 1997, Inc., a Delaware corporation

                                   By:________________________
                                          Its:

                           By:_____________________________________
                                      Ira Brind

                           By:_____________________________________
                                      Bruce Lindsay

                                       7

<PAGE>

                                  CMS DIVERSIFIED PARTNERS, L.P.
                                  By: CMS/DP Associates, L.P, a general partner
                                  By: MSPS/DP, Inc., its general partner

                                  By:______________________
                                      (Vice) President

                                  By: CMS 1995 Investment Partners, L.P, a
                                      general partner
                                      By: CMS 1995, Inc., its general
                                          partner

                                          By:____________________________
                                                 (Vice) President

                                        CMS PEP XIV CO-INVESTMENT SUBPARTNERSHIP

                                        By:_____________________________________
                                                  Richard Mitchell
                                                  Authorized Representative

                                          EURAZEO

                                          By:___________________________________
                                             Name:
                                             Title:

                                          DB CAPITAL INVESTORS, L.P.

                                          By:  DB Capital Partners, L.P.,
                                               its General Partner

                                          By:  DB Capital Partners, Inc.,
                                               its General Partner

                                          By:________________________________
                                               Name:
                                               Title:

                                        8

<PAGE>

                        GS PRIVATE EQUITY PARTNERS II, L.P.

                        By:  GS PEP II Advisors, L.L.C., its General Partner

                        By:  GSAM Gen-Par, L.L.C., its Managing Member

                        By:___________________________________________________
                             Name:
                             Title:

                        GS PRIVATE EQUITY PARTNERS II OFFSHORE, L.P.

                        By:  GS PEP II Offshore Advisors, Inc., its General
                             Partner

                        By:___________________________________________________
                             Name:
                             Title:

                        GS PRIVATE EQUITY PARTNERS II - DIRECT
                        INVESTMENT FUND, L.P.

                        By:   GS PEP II Direct Investment Advisors, L.L.C., its
                              General Partner

                        By:   GSAM Gen-Par, L.L.C., its Managing Member

                        By:___________________________________________________
                              Name:
                              Title:

                                       9

<PAGE>

                            GS PRIVATE EQUITY PARTNERS III, L.P.

                            By: GS PEP III Advisors, L.L.C., its General Partner

                            By: GSAM Gen-Par, L.L.C., its Managing Partner

                            By:____________________________________________
                                Name:
                                Title:

                            GS PRIVATE EQUITY PARTNERS III OFFSHORE, L.P.

                            By: GS PEP III Offshore Advisors, Inc., its General
                                Partner

                            By:____________________________________________
                                Name:
                                Title:

                            NBK/GS PRIVATE EQUITY PARTNERS, L.P.

                            By: GS PEP Offshore Advisors (NBK), Inc. General
                                Partner

                            By:____________________________________________
                                Name:

                                Title:

                                       10

<PAGE>

                                       HAMILTON LANE PRIVATE EQUITY PARTNERS,
                                         L.P.

                                       By: HLSP Investment Management, LLC,
                                           its General Partner

                                       By: _____________________________________
                                              Mario L. Giannini
                                              Managing Member

                                       HAMILTON LANE PRIVATE EQUITY FUND, PLC

                                       By: _____________________________________
                                              Mario L. Giannini, Director

                                       By: _____________________________________
                                              Leslie Brun, Director

                                       11

<PAGE>

                                          NASSAU CAPITAL PARTNERS III L.P.

                                          By:___________________________________
                                              Name:
                                              Title:

                                          NASSAU CAPITAL PARTNERS IV L.P.

                                          By:___________________________________
                                              Name:
                                              Title:

                                          NAS PARTNERS LLC

                                          By:___________________________________
                                              Name:
                                              Title:

                                    A.S.F. CO-INVESTMENT PARTNERS, L.P.
                                    By: PAF 10/98, LLC
                                        By: Old Kings I, LLC, as Managing Member

                                    By:_________________________________________
                                        Name:
                                        Title:

                                 NEW YORK LIFE CAPITAL PARTNERS, L.P.

                                 By: NYLCAP Manager LLC, its Investment Manager

                                 By:___________________________________________
                                     Name:
                                     Title:

                                       12

<PAGE>

                                   FERRER FREEMAN THOMPSON & CO., LLC

                                   on behalf of FFT PARTNERS I, L.P.
                                        and as its General Partner

                                        By:_____________________________________
                                               Name:
                                               Title:

                                        and

                                   on behalf of FFT EXECUTIVE PARTNERS I,
                                        L.P. and as its General Partner

                                        By:_____________________________________
                                               Name:
                                               Title:

                                        and

                                   on behalf of FFT PARTNERS II, L.P.
                                        and as its General Partner

                                        By:_____________________________________
                                               Name:
                                               Title:

                                       13

<PAGE>

                                                                      SCHEDULE I
                                                                      ----------

                              Schedule I Purchasers
                              ---------------------

                                  See attached.

Address for Schedule I Purchasers:
----------------------------------

c/o     Welsh, Carson, Anderson & Stowe
        320 Park Avenue, Suite 2500
        New York, New York 10022
        Attention: Paul B. Queally
        Telecopy: (212) 893-9566

<PAGE>

                                                                     SCHEDULE II
                                                                     -----------

                                 FFT Purchasers
                                 --------------

                                  See attached.

Address for FFT Purchasers:
---------------------------

c/o   Ferrer Freeman Thompson & Co.
       The Mill
       10 Glenville Street
       Greenwich, Connecticut  06831
       Attention:  Carlos Ferrer
       Telecopy:  (203) 532-8016

       with a copy to:

       Fried, Frank, Harris, Shriver & Jacobson
       One New York Plaza
       New York, New York 10004
       Attention:  David Golay
       Telecopy:  (212) 859-8164<PAGE>

                                                                    EXHIBIT 4.15

                               AMENDMENT NO. 2 TO
                          REGISTRATION RIGHTS AGREEMENT

         AMENDMENT NO. 2 TO REGISTRATION RIGHTS AGREEMENT (this "Amendment")
                                                                 ---------
dated as of November 5, 2001 by and among Concentra Inc., a Delaware corporation
formerly known as Concentra Managed Care, Inc. (the "Company"), the several
                                                     -------
Schedule I Purchasers signatory hereto and the several FFT Purchasers signatory
hereto. Capitalized terms used in this Amendment which are not otherwise defined
herein shall have the meanings ascribed to them in the Registration Rights
Agreement referred to below.

                              W I T N E S S E T H:
                              - - - - - - - - - -

         WHEREAS, the Company, the Schedule I Purchasers and the FFT Purchasers
are parties to a Registration Rights Agreement dated as of August 17, 1999 (as
amended, the "Registration Rights Agreement");
              -----------------------------

         WHEREAS, the Company, NHR Acquisition Company, Inc., a Delaware
corporation and wholly-owned subsidiary of the Company ("Merger Corp"), and
                                                         -----------
National Health Resources, Inc., a Delaware corporation ("NHR") are parties to a
                                                          ---
Merger Agreement dated as of the date hereof (the "Merger Agreement"), pursuant
                                                   ----------------
to which, at the Effective Time (such term being used in this Agreement as
defined in the Merger Agreement), Merger Corp will be merged (the "Merger") with
                                                                   ------
and into NHR with NHR surviving the Merger as a wholly-owned subsidiary of the
Company;

         WHEREAS, pursuant to and in accordance with the Merger Agreement, at
the Effective Time, all shares of capital stock of NHR held by the stockholders
of NHR (other than those which are Schedule I Purchasers or Affiliates thereof)
(the "NHR Holders") shall be converted into the right to receive cash and/or
 ----------------
shares of Company Common Stock (such shares, the "NHR Shares");
                                                  ----------

         WHEREAS, it is a condition to the obligation of NHR to consummate the
Merger that the Company shall have executed and delivered a Stockolders
Agreement in the form of Exhibit A hereto (the "NHR Stockholders Agreement")
                         ---------              --------------------------
pursuant to which the NHR Holders shall be granted certain registration rights
relating to the NHR Shares; and

         WHEREAS, the parties hereto desire to execute and deliver this
Amendment in order to fulfill such condition and permit the Company to grant
such registration rights contemplated by the NHR Stockholders Agreement;

         NOW, THEREFORE, in consideration of the premises and of the mutual
covenants and agreements herein contained, the parties hereto hereby agree as
follows:

<PAGE>

         SECTION 1.   Operative Provisions.
                      --------------------

         (a)   Section 4(c) of the Registration Rights Agreement is amended by
deleting the text "sold by the Company for its own account" appearing in the
first sentence thereof and inserting the text "sold by the Company or its own
account or for the account of others stockholders of the Company" in lieu
thereof.

         (b)   Notwithstanding anything to the contrary contained in Section
13(d) of the Registration Rights Agreement, the holders of a majority in
interest of the Restricted Stock held by the Schedule I Purchasers and the
holders of a majority in interest of the Restricted Stock held by the FFT
Purchasers consent to the Company's execution, delivery and performance of the
NHR Stockholders Agreement.

         SECTION 2.   Miscellaneous.
                      -------------

         (a)   This Amendment shall be governed by and construed in accordance
with the laws of the State of New York.

         (b)   This Amendment may be executed in two or more counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

         (c)   Headings and section reference numbers in this Amendment are for
reference purposes only and shall not in any way affect the meaning or
interpretation of this Amendment.

         (d)   This Amendment is limited precisely as written and shall not be
deemed to be a modification, acceptance or waiver of any other term, condition
or provision of the Registration Rights Agreement.

<PAGE>

         IN WITNESS WHEREOF, each of the parties hereto has executed this
Amendment No. 2 to Registration Rights Agreement, all as of the day and year
first above written.

                                       CONCENTRA INC.

                                       By: /s/ RICHARD A. PARR II
                                           -------------------------------------
                                           Name:  Richard A. Parr II
                                           Title: Executive Vice President,
                                                  General Counsel and Secretary

<PAGE>

                                       WELSH, CARSON, ANDERSON & STOWE
                                       VIII, L.P.

                                       By:  WCAS VIII Associates, L.L.C.,
                                            General Partner

                                       By:______________________________________
                                          Managing Member

                                       WCAS HEALTHCARE PARTNERS, L.P.
                                       By: WCAS HC Partners, General Partner

                                       By:______________________________________
                                          General Partner

                                       Patrick J. Welsh
                                       Russell L. Carson
                                       Bruce K. Anderson
                                       Andrew M. Paul
                                       Thomas E. McInerney
                                       Robert A. Minicucci
                                       Anthony J. deNicola
                                       Paul B. Queally
                                       Lawrence B. Sorrel
                                       D. Scott Mackesy
                                       Priscilla A. Newman
                                       Laura M. VanBuren
                                       Sean M. Traynor
                                       John Almedia, Jr.
                                       Jonathan M. Rather

                                       By: /s/ JONATHAN M. RATHER
                                           -------------------------------------
                                           Jonathan M. Rather, Individually and
                                           as Attorney-in-Fact

                                       WCAS MANAGEMENT CORP

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       J.P. MORGAN DIRECT CORPORATE FINANCE
                                       INSTITUTIONAL INVESTORS LLC

                                       By:______________________________________
                                          Name:
                                          Title:

                                       J.P. MORGAN DIRECT CORPORATE FINANCE
                                       PRIVATE INVESTORS LLC

                                       By:______________________________________
                                          Name:
                                          Title:

                                       522 FIFTH AVENUE FUND, L.P.

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       CALIFORNIA PUBLIC EMPLOYEES' RETIREMENT
                                       SYSTEM

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       CALIFORNIA STATE TEACHERS' RETIREMENT
                                       SYSTEM

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       CMS CO-INVESTMENT SUBPARTNERSHIP II
                                       By: CMS CO-INVESTMENT SUBPARTNERSHIP,
                                           a Delaware general partnership
                                           By: CMS Co-Investment Partners, L.P.,
                                               a Delaware limited partnership
                                               By: CMS/Co-Investment Associates,
                                                   L.P., a Delaware limited
                                                   partnership
                                                   By: MSPS/Co-Investment, Inc.,
                                                       a Delaware corporation

                                               By:______________________________
                                               Its:

                                               By: CMS 1997 Investment Partners,
                                                   L.P., a Delaware limited
                                                   partnership

                                                   By: CMS 1997, Inc., a
                                                       Delaware corporation

                                                       By:______________________
                                                       Its:

                                           By: CMS Co-Investment Partners I-Q,
                                               L.P., a Delaware limited
                                               partnership

                                               By: CMS/Co-Investment Associates,
                                                   L.P., a Delaware limited
                                                   partnership

                                                   By: MSPS/Co-Investment, Inc.
                                                       a Delaware corporation

                                                       By:______________________
                                                       Its:

                                           By: CMS 1997 Investment Partners,
                                               L.P., a Delaware limited
                                               partnership

                                               By: CMS 1997, Inc., a Delaware
                                                   corporation

                                                   By:__________________________
                                                   Its:

                                       By: /s/ IRA BRIND
                                           -------------------------------------
                                           Ira Brind

                                       By: /s/ BRUCE LINDSAY
                                           -------------------------------------
                                           Bruce Lindsay

<PAGE>

                                       CMS DIVERSIFIED PARTNERS, L.P.
                                       By: CMS/DP Associates, L.P, a general
                                           partner
                                       By: MSPS/DP, Inc., its general partner

                                       By:______________________________________
                                          (Vice) President

                                       By: CMS 1995 Investment Partners, L.P, a
                                           general partner

                                           By: CMS 1995, Inc., its general
                                               partner

                                               By:______________________________
                                                  (Vice) President

<PAGE>

                                       CMS PEP XIV CO-INVESTMENT SUBPARTNERSHIP

                                       By: /s/ RICHARD MITCHELL
                                           -------------------------------------
                                           Richard Mitchell
                                           Authorized Representative

<PAGE>

                                       EURAZEO

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       DB CAPITAL INVESTORS, L.P.

                                       By: DB Capital Partners, L.P.,
                                           its General Partner

                                       By: DB Capital Partners, Inc.,
                                           its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       GS PRIVATE EQUITY PARTNERS II, L.P.

                                       By: GS PEP II Advisors, L.L.C., its
                                           General Partner

                                       By: GSAM Gen-Par, L.L.C., its Managing
                                           Member

                                       By:______________________________________
                                          Name:
                                          Title:

                                       GS PRIVATE EQUITY PARTNERS II OFFSHORE,
                                       L.P.

                                       By: GS PEP II Offshore Advisors, Inc.,
                                       its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

                                       GS PRIVATE EQUITY PARTNERS II - DIRECT
                                       INVESTMENT FUND, L.P.

                                       By: GS PEP II Direct Investment Advisors,
                                       L.L.C., its General Partner

                                       By: GSAM Gen-Par, L.L.C., its Managing
                                       Member

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       GS PRIVATE EQUITY PARTNERS III, L.P.

                                       By: GS PEP III Advisors, L.L.C., its
                                       General Partner

                                       By: GSAM Gen-Par, L.L.C., its Managing
                                       Partner

                                       By:______________________________________
                                          Name:
                                          Title:

                                       GS PRIVATE EQUITY PARTNERS III OFFSHORE,
                                       L.P.

                                       By: GS PEP III Offshore Advisors, Inc.,
                                       its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

                                       NBK/GS PRIVATE EQUITY PARTNERS, L.P.

                                       By: GS PEP Offshore Advisors (NBK), Inc.
                                       General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       HAMILTON LANE PRIVATE EQUITY PARTNERS,
                                       L.P.

                                       By: HLSP Investment Management, LLC,
                                       its General Partner

                                       By: /s/ MARIO L. GIANNINI
                                           -------------------------------------
                                           Mario L. Giannini
                                           Managing Member

                                       HAMILTON LANE PRIVATE EQUITY FUND, PLC

                                       By: /s/ MARIO L. GIANNINI
                                           -------------------------------------
                                           Mario L. Giannini, Director

                                       By: /s/ LESLIE BRUN
                                           -------------------------------------
                                           Leslie Brun, Director

<PAGE>

                                       NASSAU CAPITAL PARTNERS III L.P.

                                       By:______________________________________
                                          Name:
                                          Title:

                                       NASSAU CAPITAL PARTNERS IV L.P.

                                       By:______________________________________
                                          Name:
                                          Title:

                                       NAS PARTNERS LLC

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       A.S.F. CO-INVESTMENT PARTNERS, L.P.
                                       By: PAF 10/98, LLC
                                           By: Old Kings I, LLC, as Managing
                                           Member

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       NEW YORK LIFE CAPITAL PARTNERS, L.P.

                                       By: NYLCAP Manager LLC, its Investment
                                       Manager

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                       FERRER FREEMAN THOMPSON & CO., LLC

                                       on behalf of FFT PARTNERS I, L.P. and as
                                         its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

                                       and

                                       on behalf of FFT EXECUTIVE PARTNERS I,
                                         L.P. and as its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

                                       and

                                       on behalf of FFT PARTNERS II, L.P. and as
                                         its General Partner

                                       By:______________________________________
                                          Name:
                                          Title:

<PAGE>

                                                                       EXHIBIT A
                                                                       ---------

                       Form of NHR Stockholders Agreement
                       ----------------------------------

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