Document:

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                                                                     Exhibit 4.3

                            OCTOBER 2000 AMENDMENT TO
                              HEALTHGATE DATA CORP.
                             1994 STOCK OPTION PLAN

         THIS OCTOBER 2000 AMENDMENT TO HEALTHGATE DATA CORP. 1994 STOCK OPTION
PLAN shall be effective as of October 5, 2000.

         WHEREAS, HealthGate Data Corp. (the "Company") maintains the HealthGate
Data Corp. 1994 Stock Option Plan (the "1994 Plan");

         WHEREAS, by previous amendments to the Plan, the number of shares of
the Company's Common Stock which may be issued and sold by the Company pursuant
to Stock Options under the 1994 Plan was increased to 3,599,997 shares;

         WHEREAS, by resolution approved by the Board of Directors of the
Company on May 15, 2000, and by vote of the stockholders of the Company on
October 5, 2000, the number of shares that may be sold pursuant to Stock Options
under the Plan was increased from 3,599,997 shares to 4,480,000 shares;

         NOW, THEREFORE, in consideration of the foregoing premises, the 1994
Plan is hereby amended as follows:

         1. NUMBER OF SHARES. The number of shares of the Company's Common Stock
that may be sold pursuant to Stock Options granted under the 1994 Plan shall be
increased from 3,599,997 shares to 4,480,000 shares.

         IN WITNESS WHEREOF, the undersigned has executed this October 2000
Amendment to be effective as of the date first above written.

                                        HEALTHGATE DATA CORP.

                                        By:      /s/ William S. Reece
                                           ----------------------------
                                            William S. Reece
                                            Chairman & Chief Executive Officer<PAGE>

                                SECOND AMENDMENT
                                       TO
                           SECOND AMENDED AND RESTATED
                          LIMITED PARTNERSHIP AGREEMENT
                                       OF
                        CORPORATE OFFICE PROPERTIES, L.P.

     THIS SECOND AMENDMENT (the "Amendment") to the Second Amended and Restated
Limited Partnership Agreement of Corporate Office Properties, L.P., a Delaware
limited partnership (the "Partnership") is made and entered into as of December
21, 1999, by and among the undersigned parties.

                                    RECITALS

     A. The Partnership is a limited partnership organized under the Delaware
Revised Uniform Limited Partnership Act and governed by that certain Seconded
Amended and Restated Limited Partnership Agreement dated as of December 7, 1999,
as amended by that certain First Amendment to Second Amended and Restated
Limited Partnership Agreement dated December 21, 1999 (as amended, the
"Partnership Agreement").

     B. The sole general partner of the Partnership is Corporate Office
Properties Trust, a real estate investment trust formed under the laws of the
State of Maryland (the "General Partner").

     C. COPT Acquisitions, Inc., a Delaware corporation and subsidiary of the
Partnership, has entered into a certain Contribution Agreement (the
"Contribution Agreement") dated as of December 3, 1999 with United Properties
Group, Incorporated, a New York Corporation ("UPG"), which Contribution
Agreement has been assigned to the Partnership in accordance with its terms.

     D. As required under Sections 2.2 and 3.1 of the Contribution Agreement,
UPG intends to transfer certain membership interests in certain limited
liability companies (the "Contributed Interests") to the Partnership in exchange
for partnership interests in the Partnership having designations, rights and
preferences as set forth in Sections 3 and 4 of the Contribution Agreement (the
"Series C Preferred Units").

     E. The parties desire to amend the Partnership Agreement to provide for the
contribution of the Contributed Interests by UPG to the Partnership in exchange
for the Series C Preferred Units in accordance with Section 3.1 of the
Contribution Agreement. Unless otherwise defined herein, all capitalized terms
used in this Amendment shall have the same meanings as set forth in the
Partnership Agreement.

     NOW THEREFORE, in consideration of the foregoing and of the mutual premises
set forth herein, the parties hereto, intending to be legally bound hereby,
hereby amend the Partnership Agreement as follows, effective as of the date set
forth above.

<PAGE>

     1. The foregoing recitals to this Amendment are hereby incorporated in and
made a part of this Amendment.

     2. (a) Upon closing of the Contribution Agreement, UPG shall contribute the
Contributed Interests to the Partnership.

        (b) Upon the contribution of the Contributed Interests to the
Partnership by UPG, and in accordance with Section 3.1 of the Contribution
Agreement, the Partnership shall issue to UPG 974,662 Series C Preferred Units,
which Preferred Units shall constitute Senior Preferred Units.

        (c) For purposes of the Partnership Agreement, including the maintenance
of Capital Accounts, UPG shall be treated as making a Capital Contribution of
$24,366,546.16, equal to the net asset value of the Contributed Interests.

        (d) The General Partner shall amend Exhibit 1 to the Partnership
Agreement by adding the Addendum to Exhibit 1 in the form attached hereto to
reflect the issuance of the Series C Preferred Units to UPG and the General
Partner hereby confirms certain rights attendant thereto, including, without
limitation, the rights to the Liquidation Preference and the Priority Return
Percentage set forth therein, and the right to convert such Preferred Units into
Partnership Units at the Conversion Factor set forth therein. The Conversion
Factor for the Series C Preferred Units shall be entitled to anti-dilution
protection to the same extent as that certain Warrant to Purchase Common Units
dated of even date herewith of the Partnership in favor of UPG, granting UPG the
right to purchase Partnership Units on the terms stated therein.

     3. This Amendment shall take effect upon the closing of the transactions
contemplated by the Contribution Agreement, including without limitation the
contribution of the Contributed Interests to the Partnership by UPG, and in the
event such closing does not occur, this Amendment shall be of no force or
effect.

                  (REMAINDER OF PAGE INTENTIONALLY LEFT BLANK)

                                       2
<PAGE>

     In witness whereof, the parties hereto have caused their duly authorized
representatives to execute this Amendment as of the day and year first above
written.

                                   UNITED PROPERTIES GROUP, INCORPORATED, a
                                   New York corporation

                                   By: /s/ JOSEPH S. THOMPSON
                                       --------------------------------
                                   Name:    Joseph S. Thompson
                                   Its:     Vice President

                                   CORPORATE OFFICE PROPERTIES TRUST, a
                                   Maryland Real Estate Investment Trust

                                   By: /s/ ROGER A. WAESCHE, JR.
                                       ---------------------------------
                                   Name:    Roger A. Waesche, Jr.
                                   Its:     Senior Vice President

                                       3
<PAGE>

                                                                       Exhibit 1
                              SCHEDULE OF PARTNERS
<TABLE>
<CAPTION>

                                                                                 Series A      Series B       Series C
                                                                                 Preferred     Preferred      Preferred
                                                                 Partnership    Partnership   Partnership    Partnership
                                                                    Units          Units         Units          Units
                                                                 ------------- -------------- ------------- --------------
<S>                                                              <C>           <C>            <C>           <C>
GENERAL PARTNER
---------------
Corporate Office Properties Trust                                15,503,088        984,308     1,250,000
LIMITED PARTNERS AND PREFERRED LIMITED PARTNERS
-----------------------------------------------
United Properties Group, Incorporated                                                                           974,662
Jay H. Shidler                                                      452,878
Shidler Equities, L.P.                                            2,217,182
Clay W. Hamlin, III                                                 417,138
LBCW Limited Partnership                                          3,246,007
CHLB Partnership                                                    212,316
Robert L. Denton                                                    434,910
James K. Davis                                                       51,589
John E. De B. Blockey, Trustee of the John E. de B. Blockey
  Living Trust dated 9/12/88                                        300,625
Henry  D. Bullock                                                   116,553
Frederick K. Ito Trust                                               29,140
June Y. I. Ito Trust                                                 29,135
Bernice Reger                                                       268,671
Tiger South Brunswick, L.L.C.                                         6,778
Westbrook Real Estate Fund I, L.P.                                  792,279
Westbrook Real Estate Co. Investment Partnership I, L.P.             78,488
Denise J. Liszewski                                                  34,333
Samuel Tang                                                          22,889
David P. Hartsfield                                                  30,519
Lawrence J. Taff                                                     13,733
Kimberly F. Acquino                                                   5,874
M.O.R. XXIX Associates Limited Partnership                          148,381
M.O.R. 44 Gateway Associates Limited Partnership                          1
Enterprise Nautical, Inc.                                           100,000
John Parsinen                                                        90,000
John D. Parsinen, Jr.                                                10,000
New Parkway Domain Group Enterprises, LLC                           326,768
M.O.R. Commons Limited Partnership                                        7
John Edward De Burgh Blockey and Sanda Juanita Blockey               50,476
                                                                 ----------        -------     ---------        -------
                                                                 24,989,758        984,308     1,250,000        974,662
                                                                 ==========        =======     =========        =======
</TABLE>

                                       4
<PAGE>

                                                              EXHIBIT 1 ADDENDUM

<TABLE>
<CAPTION>

                                                Liquidation
                                                Preference
  Series                            No. of         Per        Priority                                     Conversion
 Preferred      Preferred          Preferred     Preferred     Return                    Conversion       Commencement
   Units      Limited Partner        Units          Unit      Percentage*    Priority      Factor              Date
 ---------    ---------------      ---------    -----------   ----------     --------    ----------       ------------
<S>          <C>                   <C>          <C>           <C>            <C>         <C>              <C>
     A       General Partner         984,308        $25          1.375%        Senior       1.8748          8/28/2000
     B       General Partner       1,250,000        $25          2.50%         Senior        None              N/A
     C              UPG              974,662        $25            **          Senior        2.381          12/22/2000
</TABLE>

----------

*    Priority Return Percentage is expressed per Distribution Period.

**   Priority Percentage Return for the Series C Preferred Units shall be:
     2.25% from December 21, 1999 to December 20, 2009;
     2.625% from December 21, 2009 to December 20, 2014; and 3.00% thereafter.
     The Distribution Period for the Series C Preferred Units shall be each
     calendar quarter ending March 31, June 30, September 30 and December 31 of
     each year.

                                       5

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