Document:

<PAGE>   1

                                                                   EXHIBIT 10.55

                 AMENDMENT NO. 1 TO CERTAIN OPERATIVE AGREEMENTS

       THIS AMENDMENT NO. 1 (this "Amendment") dated as of March 14, 2000, is by
and among SUNRISE MIDWEST LEASING, L.L.C., a Virginia limited liability company
(the "Lessee" or the "Construction Agent"); SUNRISE ASSISTED LIVING, INC., a
Delaware corporation (the "Guarantor"); FIRST SECURITY BANK, NATIONAL
ASSOCIATION, a national banking association, not individually but solely as the
Owner Trustee under the Sunrise Trust 1998-1 (the "Owner Trustee" or the
"Lessor"); the various banks and other lending institutions listed on the
signature pages hereto (subject to the definition of Lenders in Appendix A to
the Participation Agreement referenced below, individually, a "Lender" and
collectively, the "Lenders"); BANK OF AMERICA, N.A., a national banking
association, which is the successor to NationsBank, N.A., as the agent for the
Lenders and respecting the Security Documents, as the agent for the Lenders and
the Holders, to the extent of their interests (in such capacity, the "Agent");
and the various banks and other lending institutions listed on the signature
pages hereto as holders of certificates issued with respect to the Sunrise Trust
1998-1 (subject to the definition of Holders in Appendix A to the Participation
Agreement referenced below, individually, a "Holder" and collectively, the
"Holders"). Capitalized terms used in this Amendment but not otherwise defined
herein shall have the meanings set forth in Appendix A to the Participation
Agreement (hereinafter defined).

                               W I T N E S S E T H

       WHEREAS, the parties to this Amendment are parties to that certain
Participation Agreement dated as of December 2, 1998 (the "Participation
Agreement") and certain of the parties to this Amendment are parties to the
other Operative Agreements relating to a $47 million tax retention operating
lease facility that has been established in favor of the Lessee;

       WHEREAS, the Lessee has requested certain modifications to the
Participation Agreement and the other Operative Agreements;

       WHEREAS, the Financing Parties have agreed to the requested modifications
on the terms and conditions set forth herein;

       NOW, THEREFORE, IN CONSIDERATION of the premises and other good and
valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, the parties agree as follows:

<PAGE>   2

                             PARTICIPATION AGREEMENT

       1. Appendix A to the Participation Agreement is hereby amended to add or
modify the following defined terms:

       "Adjusted Properties EBITDAR" means, for the Properties and each property
comprising the Residual Payment Collateral for any period, earnings before
interest, federal and state income taxes, depreciation, amortization and rent,
but after an imputed replacement reserve of $250 per year per bed in each
facility that is open for operation and a management fee equal to the greater of
5% for gross revenues or the actual management fee paid to the Management
Company.

       "Assets Held for Sale" shall mean each of the properties listed on
Schedule I attached hereto, which are currently being held by SALI (or an
Affiliate of SALI) for resale.

       "Convertible Debt" shall mean the $150 million convertible subordinated
notes of SALI due 2002.

       "EBITDAR" means earnings before interest, federal and state income taxes,
depreciation, amortization, and any other non-cash and one-time, non-recurring
charges consented to by the Agent in its sole discretion (provided that the
consent of the Majority Secured Parties shall be required for adding back
charges in excess of $5,000,000 in the aggregate in any one year, but after an
imputed Replacement Reserve and a Management Fee equal to the greater of 5% of
the gross revenues or the actual Management Fee paid to the Management Company,
plus Rent Expense. Earnings shall include income from "Assets Held for Sale"
through the date on which any such asset is actually sold and shall include the
gain from any sale of an open operating Facility owned by SALI or an Affiliate
of SALI up to but not exceeding an aggregate of twenty (20) of such sales in any
twelve (12) month period; provided, however, that other one-time non-recurring
gains including those from sales of Assets Held for Sale will not be included in
EBITDAR.

       "Facility" shall mean, individually or collectively, an assisted living
facility or independent living facility owned by the Lessee, SALI or any
Affiliate of the Lessee or SALI.

       "Funded Debt" of SALI at any time means the sum at such time of (a)
indebtedness for borrowed money (including specifically but without limiting the
generality of the foregoing, the Convertible Debt), (b) any obligations in
respect of letters of credit, banker's or other acceptances or similar
obligations issued or created for the account of SALI, (c) lease obligations
which have been or should be, in accordance with GAAP, capitalized on the books
of SALI, (d) all liabilities secured by any property owned by SALI to the extent
attached to SALI's interest in such property, even though SALI has not assumed
or become liable for the payment thereof, and in the case of SALI, (e) (i)
amounts payable by SALI under any terminated or defaulted interest rate
protection products or which remain outstanding or (ii) take-out commitments
(excluding a refinancing or a commitment of a third party) or purchase contracts
including the deferred purchase price of property or services in each instance
if SALI does not control the incurring obligation, (f) (i) the amount of any
guaranty of indebtedness for borrowed money or (ii) other

                                       2
<PAGE>   3

debt owed by Persons other than SALI which is in default and for which the
creditor is pursuing payment by SALI, (g) any obligation of SALI or a Commonly
Controlled Entity to a Multiemployer Plan, (h) any synthetic lease obligations,
(i) any other lease expenses for rented real property will be accounted for as
debt based on eight times annualized lease payments (provided, however, that so
long as SALI or any Affiliate of SALI shall continue to own a 50% interest in
the Facility located in Severna Park, Maryland known as "Sunrise of Severna
Park," lease expenses for Sunrise of Severna Park will be accounted for as debt
based on four times the annualized lease payments rather than eight times the
annualized lease payments and (j) other amounts considered to be debt by the
Agent in a dollar amount to be mutually agreed upon by the Agent and SALI, but
excluding trade and other accounts payable in the ordinary course of business in
accordance with customary trade terms and which are not overdue (as determined
in accordance with customary trade practices) or which are being disputed in
good faith by SALI and for which adequate reserves are being provided on the
books of SALI in accordance with GAAP, all of the above whether recourse or
non-recourse, secured or unsecured.

       "Management Fees" shall mean any and all management fees under, or in
connection with the Management Agreement.

       "Rent Expense" shall mean the actual rent expense incurred by the Lessee,
SALI or any Affiliate of the Lessee or SALI as a tenant under leases with
respect to any Facility.

       "Replacement Reserves" shall mean $250 per year per bed in each Facility
(whether or not such Facility is stabilized).

       "Tangible Net Worth" means, at any time, the sum at such time of Net
Worth (as defined by GAAP) plus the dollar amount of the leasehold value
associated with the Properties (which leasehold value would otherwise be
categorized as an intangible asset on the financial statements of SALI) less the
total of (i) all assets which would be classified as intangible assets under
GAAP, including goodwill (except for the goodwill purchased in connection with
the acquisition of Karrington Health, Inc. in the approximate amount of
$32,000,000 (subject to adjustment for final audited calculations as of December
31, 1999 and as may be further adjusted as reported in future Form 10Q Reports
of SALI), which shall be included in Tangible Net Worth and except for deferred
taxes recorded as goodwill), trademarks, trademark applications, trade names,
service marks, patent applications and licenses, and deferred charges, (ii) any
revaluation or other write-up in book value of assets subsequent to the date of
the most recent financial statements delivered to the Agent, (iii) the amount of
all loans and advances to, or investments in, any person of entity, excluding
cash equivalents and deposit accounts maintained by SALI with any financial
institution, (iv) advances or loans made to or receivables from any
unconsolidated affiliates (excluding subordinated debt or loans of
unconsolidated subsidiaries and affiliates of SALI which are parties to
development and management contracts with Sunrise Development, Inc. and Sunrise
Assisted Living Management, Inc.) of which SALI owns less than fifty percent
(50%) or any stockholder of SALI or any affiliate and (v) the amount of all
loans and advances to, or investments in, any person or entity, excluding loans
to Karrington and its affiliates, cash equivalents and deposit accounts
maintained by SALI with any financial institutions, certain mortgage revenue
bonds issued by the Bucks County, Pennsylvania Industrial Development

                                       3
<PAGE>   4

Authority and investments of less than $2,500,000 individually (not to exceed
$10,000,000 in the aggregate).

       2. Section 8.3B.2(a) of the Participation Agreement is hereby amended to
read as follows:

          (a) Minimum Tangible Net Worth. SALI shall maintain, on a consolidated
basis with all Subsidiaries, at all times measured quarterly beginning with the
quarter ending September 30, 1999, a minimum Tangible Net Worth of not less than
the sum of a $258,003,069 plus 75% of SALI's net income (if positive) for each
subsequent quarter, plus 85% of the net proceeds to SALI of any equity capital
transaction received during any subsequent quarter.

       3. Section 8.3B.2(c) of the Participation Agreement is hereby amended to
read as follows:

          (c) Funded Debt to EBITDAR. SALI shall maintain as of the end of each
fiscal quarter (beginning with the fiscal quarter ending December 31, 1999) a
ratio of Funded Debt as of such date to EBITDAR for SALI on a consolidated basis
for the period of four consecutive fiscal quarters listed below (each, a
"Period"), of not more than:

 <TABLE>
 <CAPTION>

<S>     <C>                                                                             <C>
          Period 1     From December 31, 1999 to and including September 30, 2000           8.75:1.00

          Period 2     From December 31, 2000 to and including September 30, 2001           7.75:1.00

          Period 3     From December 31, 2001 and thereafter                                7.00:1.00
</TABLE>

Notwithstanding the foregoing, in the event that SALI or any of its Affiliates
sells more than ten (10) Facilities (other than Assets Held for Sale) during
fiscal year 2000, the foregoing maximum ratio will be reduced to 7.75 to 1.00
effective as of the end of the fiscal quarter in which the closing of the sale
of the tenth Facility occurred.

       4. Section 8.3B.2(e) of the Participation Agreement is hereby amended to
read as follows:

          (e) Aggregate Adjusted EBITDAR to Debt Service for the Properties.
Maintain as of the end of the fiscal quarters shown below a ratio (for all
Properties and all properties comprising the Residual Payment Collateral in the
aggregate) of (i) Adjusted Properties EBITDAR for the period of two (2)
consecutive fiscal quarters then ended multiplied by two to (ii) Annual
Properties Debt Service, of not less than:

<TABLE>
<CAPTION>
      Fiscal Quarter Ending
      ---------------------
<S>                                                                   <C>
      December 31, 1999                                                   1.0:1.0
      March 31, 2000                                                      1.2:1.0
      June 30, 2000 and each fiscal quarter thereafter                   1.35:1:0
</TABLE>

                                       4
<PAGE>   5

       5. Section 8.3B.2(f) of the Participation Agreement is hereby deleted.

       6. Section 8.9 of the Participation Agreement is hereby amended to read
as follows:

8.9    RELEASE OF RESIDUAL PAYMENT COLLATERAL.

       The Residual Payment Collateral located in Raleigh, North Carolina
identified on Exhibit N hereto (the "Raleigh Property") will be promptly
released, at the request and expense of SALI, at any time after the ratio of
Adjusted Properties EBITDAR (exclusive of the Adjusted Properties EBITDAR
generated by the Raleigh Property) to Annual Properties Debt Service shall be
equal to or greater than 1.60:1.0 as of the last day of at least two (2)
consecutive fiscal quarters (such calculation to be made, for purposes of this
section, by annualizing the results for the two quarter period ending of the
last day of each such fiscal quarter), provided that no Default or Event of
Default shall then exist and be continuing. The Agent is specifically authorized
and directed by the Lenders and the Holders to take such action as is necessary
or appropriate to give effect to such release.

       7. The following sentence is hereby added at the end of Section 8.3B.3(b)
of the Participation Agreement:

       "Without limiting the generality of the foregoing, SALI and its
       Subsidiaries will not sell more than twenty (20) Facilities (excluding
       Facilities now classified as Assets Held for Sale) during any twelve (12)
       month period without the prior written consent of the Majority Secured
       Parties."

       8. The schedule of Residual Payment Collateral attached as Exhibit N to
the Participation Agreement is hereby deleted and replaced with the following
page:

                  [Remainder of Page Intentionally Left Blank]

                                       5
<PAGE>   6

                                    EXHIBIT N
                           Residual Payment Collateral

Montgomery County (Blue Bell), Pennsylvania
Wake County (Raleigh), North Carolina

                  [Remainder of Page Intentionally Left Blank]

                                       6
<PAGE>   7

                                  MISCELLANEOUS

       9. This Amendment shall be effective upon satisfaction of the following
conditions:

          (a) execution and delivery of this Amendment by the parties hereto and
       execution and delivery of such other documents, agreements or instruments
       deemed necessary or advisable by the Agent; and

          (b) (i) receipt by the Agent of an officer's certificate of the Lessee
       and the Construction Agent (in form and in substance reasonably
       satisfactory to the Agent) certifying that a resolution has been adopted
       by Lessee's Board of Directors approving and authorizing the execution,
       delivery, and performance of this Amendment, specifying that no Default
       or Event of Default shall have occurred and be continuing, specifying
       that the representations and warranties of Lessee and the Guarantor set
       forth in the Participation Agreement are true and correct (except for any
       such representations and warranties which relate solely to an earlier
       time) and certifying as to the incumbency of the officer of Lessee
       executing this Amendment and (ii) receipt by the Agent of an officer's
       certificate of the Guarantor (in form and in substance reasonably
       satisfactory to the Agent) certifying that a resolution has been adopted
       by such Credit Party's Board of Directors approving and authorizing the
       execution, delivery and performance of this Amendment and certifying as
       to the incumbency of the officer of the Guarantor executing this
       Amendment; and

          (c) receipt by the Agent of legal opinions of counsel to the Lessee
       relating to this Amendment in form and substance reasonably satisfactory
       to the Agent; and

          (d) receipt by the Agent, on behalf of each Lender and each Holder, of
       an amendment fee equal to the product of one eighth of one percent
       (0.125%) multiplied by the sum of the aggregate Commitments and the
       aggregate Holder Commitments (after giving effect to the reduction in the
       aggregate Commitments and the aggregate Holder Commitments as a result of
       the purchase by Lessee of the Properties more particularly identified on
       Schedule II attached hereto pursuant to subsection (e) of this Section);
       and

          (e) receipt by the Agent of the Termination Value for each of the
       Properties more particularly identified on Schedule II attached hereto
       and conveyance by Lessor to Lessee (or Lessee's designee) of each such
       Property upon receipt of the Termination Value therefore, in accordance
       with Section 20.2 of the Lease.

       10. Except as modified hereby, all of the terms and provisions of the
Operative Agreements (including Schedules and Exhibits) shall remain in full
force and effect.

       11. The Lessee agrees to pay all reasonable costs and expenses of the
Agent in connection with the preparation, execution and delivery of this
Amendment, including without limitation the reasonable fees and expenses of
Moore & Van Allen, PLLC.

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<PAGE>   8

       12. This Amendment may be executed in any number of counterparts, each of
which when so executed and delivered shall be deemed an original and it shall
not be necessary in making proof of this Amendment to produce or account for
more than one such counterpart.

       13. This Amendment shall be deemed to be a contract made under, and for
all purposes shall be construed in accordance with the laws of the State of
Virginia.

                            [signature pages follow]

                                       8
<PAGE>   9

       IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed by their respective officers thereunto duly authorized as of the
day and year first above written.

CONSTRUCTION AGENT
AND LESSEE:                        SUNRISE MIDWEST LEASING, L.L.C., as the
                                   Construction Agent and as the Lessee
                                   by Sunrise Assisted Living Investments,
                                   Inc., as Sole Member

                                   By: /s/ James S. Pope
                                      -------------------------------------
                                   Name: James S. Pope
                                         ----------------------------------
                                   Title: Vice President
                                         ----------------------------------

GUARANTOR:                         SUNRISE ASSISTED LIVING, INC., as Guarantor

                                   By: /s/ Thomas B. Newell
                                      -------------------------------------
                                   Name:   Thomas B. Newell
                                      -------------------------------------
                                   Title:  Executive Vice President
                                      -------------------------------------

                                   By: /s/ David W. Faeder
                                      -------------------------------------
                                   Name:   David W. Faeder
                                      -------------------------------------
                                   Title:  President
                                      -------------------------------------

OWNER TRUSTEE AND
LESSOR:                            FIRST SECURITY BANK, NATIONAL
                                   ASSOCIATION, not individually, except as
                                   expressly stated herein, but solely as
                                   the Owner Trustee under the Sunrise
                                   Trust 1998-1

                                   By: /s/ Val T. Orton
                                      ------------------------------------------
                                   Name: Val T. Orton
                                        ----------------------------------------
                                   Title: Vice President
                                         ---------------------------------------

                           [signature pages continued]

<PAGE>   10

AGENT, LENDERS AND HOLDERS:       BANK OF AMERICA, N.A., as successor to
                                  NationsBank, N.A., as a Lender, as a Holder
                                  and as the Agent

                                  By: /s/ Leslie M . Zuga
                                     -------------------------------------------
                                  Name:    Leslie M. Zuga
                                      ------------------------------------------
                                  Title:   Senior Vice President
                                       -----------------------------------------

                                  FLEET NATIONAL BANK, as a Lender and as a
                                  Holder

                                  By: /s/ Patricia Marinilli
                                     -------------------------------------------
                                  Name:   Patricia Marinilli
                                       -----------------------------------------
                                  Title: Vice President
                                        ----------------------------------------

                                  PROVIDENT BANK OF MARYLAND, as a Lender and as
                                  a Holder

                                  By: /s/  Thomas C. Myers
                                     -------------------------------------------
                                  Name:    Thomas C. Myers
                                       -----------------------------------------
                                  Title:   Vice President
                                        ----------------------------------------

<PAGE>   11

                                   SCHEDULE I
             [LIST OF ASSETS HELD FOR SALE AS OF FEBRUARY 22, 2000]

Sunrise of Fremont, OH
Sunrise of Shahawn (Tiffen), OH
Sunrise of Rochester, MN
Sunrise of Bismark Commons, ND
Sunrise of Bismark Cottages, ND
Sunrise of Buffalo Cottages, MN
Sunrise of Waterloo, IA
Sunrise of Mankato, MN
Sunrise of Park Ridge, IL
Sunrise Regional Office Building, Columbus, OH

<PAGE>   12

                                   SCHEDULE II

               [Identify Charlotte, NC and Poland, OH Properties]<PAGE>   1
                          NOTE MODIFICATION AGREEMENT

                      BY AND BETWEEN BANK OF AMERICA, N.A.
                             ("BANK"/"LENDER") AND

                                 PROXICOM, INC.
                                  ("BORROWER")

                                              EFFECTIVE AS OF: NOVEMBER 29, 1999

On or about October 30, 1998, (Note Date), Borrower executed a Promissory Note
315 ("Note") in favor of Bank/Lender. This note was in the original principal
face amount of $10,000,000.00 bearing interest at Libor plus 1.50% per annum
with a stated final maturity date (including all prior renewals, if any) of
August 31, 2000. Bank/Lender remains the owner and holder of the Note and has
agreed with Borrower to modify certain provisions of the Note. Now, therefore,
in consideration of these promises and the exchange of other good and valuable
consideration, the receipt of which is hereby acknowledged, Bank/Lender and
Borrower agree to modify the Note as follows:

     The interest rate is changed to:

     EURODOLLAR DAILY FLOATING RATE. The Rate shall be the Eurodollar Daily
Floating Rate plus 1.25 percent, per annum. The "Eurodollar Daily Floating
Rate" is a fluctuating rate of interest equal to the one month rate of interest
(rounded upwards, if necessary to the nearest 1/100 of 1%) appearing on Telerate
Page 3750 (or any successor page) as the one month London interbank offered
rate for deposits in Dollars at approximately 11:00 a.m. (London time) on the
second preceding business day, as adjusted from time to time in Bank's sole
discretion for then-applicable reserve requirements, deposits insurance
assessment rates and other regulatory costs. If for any reason such rate is not
available, the term "Eurodollar Daily Floating Rate" shall mean the fluctuating
rate of interest equal to the one month rate of interest (rounded upwards, if
necessary to the nearest 1/100 of 1%) appearing on Reuters Screen LIBO Page as
the one month London interbank offered rate for deposits in Dollars at
approximately 11:00 a.m. (London time) on the second preceding business day, as
adjusted from time to time in Bank's sole discretion for then-applicable
reserve requirements, deposits insurance assessment rates and other regulatory
costs; provided, however, if more than one rate is specified on Reuters Screen
LIBO page, the applicable rate shall be the arithmetic mean of all such rates.

     The payment terms are changed to: SINGLE PRINCIPAL PAYMENT. Principal shall
be paid in full in a single payment on August 31, 2000. Interest thereon shall
be paid monthly, commencing on January 15, 2000, and continuing on the same day
of each successive month thereafter, with a final payment of all unpaid
interest at the stated maturity of this Note.

The term Borrower as used in this Agreement shall be construed as singular or
plural to correspond with the number of persons executing this Agreement as
Borrower.

All other terms, conditions and covenants in the Note shall be and remain in
full force and effect. When executed by Bank/Lender and Borrower, this
Agreement shall be attached to and become a part of the Note.

NOTICE OF FINAL AGREEMENT.

THIS WRITTEN AGREEMENT REPRESENTS THE FINAL AGREEMENT BETWEEN BORROWER AND
BANK/LENDER AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS
OR SUBSEQUENT ORAL AGREEMENTS BETWEEN BORROWER AND BANK/LENDER. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN BORROWER AND BANK/LENDER.
<PAGE>   2
IN WITNESS WHEREOF, the undersigned has caused this Note Modification Agreement
to be executed under seal by Borrower on this 15th day of December 1999.

Bank of America, N.A.

By /s/  JEAN REAVIS CROSS
  --------------------------------
Name: Jean Reavis Cross
Title: Vice President

Corporate or Partnership Borrower:            Proxicom, Inc.
                                              --------------

                                              By: /s/ CHRISTOPHER CAPUANO (Seal)
----------------------------------               -------------------------
Attest (if Applicable)
                                              Name: Christopher Capuano

(Corporate Seal)                              Title: Vice President
<PAGE>   3
BANK OF AMERICA, N.A.

                     SECOND MODIFICATION OF LOAN AGREEMENT

                                                                     S1-657824RC

THIS SECOND MODIFICATION OF LOAN AGREEMENT (this "Agreement") is made as of
December   , 1999, but is in all respects effective November 29, 1999, by and
between Proxicom, Inc. (the "Borrower") and Bank of America, N.A. (the "Bank"),
witnesseth:

WHEREAS, the Borrower executed a loan agreement (the "Loan Agreement")
outlining specific terms and conditions governing the Loan, and

WHEREAS, the Borrower has requested and the Bank has agreed to renew the Loan
provided that the Borrower executed this Agreement.

NOW, THEREFORE, in consideration of the premises, the sum of $1.00 and other
good and valuable consideration, the receipt of which is hereby acknowledged,
the parties hereto agree as follows:

1)   The statement set forth above are true and accurate in every respect and
     are incorporated herein by reference.

2)   The Loan Agreement is hereby amended as follows:

     Paragraph 6.1.(ix) is hereby deleted in its entirety.

3)   Except as expressly amended herein, all of the provisions of the Loan
     Agreement shall remain in full force and effect.  This Agreement shall in
     no way operate as a novation, release, or discharge of any of the
     provisions of the Loan Agreement (except as amended herein), or any
     indebtedness thereby evidenced.

IN WITNESS WHEREOF, and intending to create an instrument executed under seal,
the Borrower and the Bank have duly executed this Agreement under seal as of
the day and year first written above.

                                             BORROWER,
                                             Proxicom, Inc.

                                             BY: /s/ CHRISTOPHER CAPUANO (SEAL)
                                                --------------------------------
                                             Christopher Capuano, Vice President

                                             BANK:
                                             BANK OF AMERICA, N.A.

                                             BY: /s/ Jean Reavis Cross    (SEAL)
                                                --------------------------------
                                             Jean Reavis Cross, Vice President

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