Exhibit 10.5

                            FOURTH AMENDMENT TO LEASE

      THIS FOURTH AMENDMENT TO LEASE (this "Amendment") is made and entered into
as of the 11th day of July,  2005 by and  between  BROOKHAVEN  (NASHUA),  LLC, a
Delaware limited  liability company  ("Landlord")  through its Agent CORNERSTONE
REAL ESTATE ADVISERS LLC, having an address at 180 Glastonbury Boulevard,  Suite
401, Glastonbury, Connecticut 06033, and CRITICAL CARE SYSTEMS, INC., a Delaware
corporation  with an address at 61 Spit Brook Road,  Nashua,  New Hampshire (the
"Tenant").

                                    RECITALS

      WHEREAS,  Tenant and  Landlord's  predecessor-in-interest  entered  into a
certain  Lease  effective  August 4, 1996 (the "1996  Lease") of 4,574  rentable
square  feet of office  space  located  on the fifth  (5th)  floor of the office
building located at 61 Spit Brook Road,  Nashua, New Hampshire (the "Building");
and

      WHEREAS, the 1996 Lease was amended by an Amendment to Lease dated June 4,
2001 (the "First  Amendment"),  whereby  Landlord leased to Tenant an additional
3,008  square  feet of office  space  located  on the fifth  (5th)  floor of the
Building  and  commonly  known as Suite 502 and was further  amended by a Second
Amendment  to Lease  dated  June 25,  2001  (the  "Second  Amendment"),  whereby
Landlord  leased to Tenant an additional 785 square feet of office space located
on the fifth (5th) floor of the Building and commonly known as Suite 500 and was
further amended by a Third Amendment to Lease dated November 7, 2003 (the "Third
Amendment"),  whereby  Landlord leased to Tenant an additional 4,466 square feet
of office  space  located on the fifth (5th) floor of the  Building and commonly
known as Suites  503-504.  The 1996  Lease,  the  First  Amendment,  the  Second
Amendment and the Third  Amendment are hereinafter  collectively  referred to as
the "Original  Lease" and the Original Lease,  as amended by this Amendment,  is
hereinafter referred to as the "Lease";

      WHEREAS,  pursuant to the Original  Lease,  the Tenant occupies a total of
12,833 square feet of office space consisting of the entire fifth (5th) floor of
the Building (the "Original Premises").

      WHEREAS,  Landlord and Tenant have agreed:  (i) that Tenant shall lease an
additional  13,408  square feet of office  space on the third (3rd) floor of the
Building (the "Additional Premises") as shown on Exhibit A attached hereto; (ii)
to extend the term of the Original Lease with respect to the Original  Premises;
and (iii) amend  certain  provisions  of the  Original  Lease,  all as set forth
herein.

                                    AGREEMENT

      NOW THEREFORE, for the consideration provided for below and for other good
and  valuable  consideration,  the receipt and  sufficiency  of which are hereby
acknowledged, Landlord and Tenant hereby agree as follows:

<PAGE>

      1. Defined Terms.  Unless otherwise defined herein, all terms with initial
capital letters shall have the same meaning ascribed to such terms in the Lease.

      2. Continuing Effect of Lease.  Except as expressly  modified hereby,  all
other terms and conditions of the Lease shall continue in full force and effect.

      3. Section 1 of the Lease,  Landlord's Name and Type of Entity,  is hereby
restated as follows:  Brookhaven  (Nashua),  LLC, a Delaware  limited  liability
company.

      4.  Section 1 of the Lease,  Landlord's  Address  for  Notices,  is hereby
restated as follows:  c/o Cornerstone  Real Estate Advisers LLC, 180 Glastonbury
Boulevard,  Suite 401, Glastonbury,  Connecticut 06033, with a copy to Cushman &
Wakefield,  125 Summer Street,  Boston,  Massachusetts 02110,  Attention:  Julia
Arsenault.

      5. Section 1 of the Lease,  Landlord's Payment Address, is hereby restated
as follows: Cushman & Wakefield, 125 Summer Street, Boston, Massachusetts 02110,
Attention: Julia Arsenault.

      6.  Section  2(b) of the  Lease is  hereby  amended  to  provide  that the
Premises  demised by the Lease shall include both the Original  Premises and the
Additional  Premises  (collectively,  the "Premises"),  and are hereby agreed to
contain  26,241  square  feet in the  aggregate,  as shown on Exhibit B attached
hereto.

      7. Exhibit B of the Lease is hereby  deleted and  replaced  with Exhibit B
attached hereto.

      8.  Section 2(d) of the Lease is hereby  amended to provide that  Tenant's
Rentable Square Feet are hereby agreed to contain 26,241 rentable square feet of
floor area.

      9.  Section 2(f) of the Lease is hereby  amended to provide that  Tenant's
Proportionate Share shall be 44.7%.

      10.  Section  2(h) of the  Lease is hereby  amended  to  provide  that the
Commencement Date for Suite numbers 301 and 304 of the Additional Premises shall
be three (3) business days after the full  execution of this  Amendment as shown
in the signature block below,  and the  Commencement  Date for Suite numbers 302
and 303 of the Additional  Premises shall be October 1, 2005, as the same may be
extended pursuant to Section 9 of the Lease, as amended herein.  The "Additional
Premises  Rent  Commencement   Date"  shall  be  January  1,  2006,  unless  the
Commencement  Date for Suite  numbers  302 and 303 shall be extended as provided
herein in which case the  Additional  Premises Rent  Commencement  Date shall be
delayed by the number of days equal to the difference  between  October 1, 2005,
and the actual date of delivery of Suites 302 and 303 to Tenant.


                                       2
<PAGE>

      11.  Section 2(i) of the Lease is hereby  amended to provide that the Term
for the Premises  shall expire on February 29, 2012, as the same may be extended
pursuant to Section 9 of the Lease, as amended herein.

      12. Section 2(j) of the Lease is hereby amended as follows:

            Base Rent for Original Premises:

--------------------------------------------------------------------------------
      Dates               Base Rent           Annual Base           Monthly Base
                             psf                 Rent                   Rent
--------------------------------------------------------------------------------
  6/1/05 - the
day prior to the
   Additional
  Premises Rent
  Commencement
      Date                  $18.00            $230,994.00            $19,249.50
--------------------------------------------------------------------------------

            Base Rent for the Premises:

--------------------------------------------------------------------------------
      Dates               Base Rent           Annual Base           Monthly Base
                             psf                 Rent                   Rent
--------------------------------------------------------------------------------
  Additional
 Premises Rent
 Commencement
 Date - Lease
    Month 20                $18.00            $472,338.00            $39,361.50
--------------------------------------------------------------------------------
Lease Month 21
- Lease Month
      32                    $19.00            $498,579.00            $41,548.25
--------------------------------------------------------------------------------
Lease Month 33
- Lease Month
      56                    $20.00            $524,820.00            $43,735.00
--------------------------------------------------------------------------------
Lease Month 57
- Lease Month
      74                    $21.00            $551,061.00            $45,921.75
--------------------------------------------------------------------------------

      Notwithstanding the foregoing, in the event Tenant occupies any portion of
the  Additional  Premises for the conduct of business  prior to January 1, 2006,
Tenant shall pay Base Rent equal to $7.80 per rentable  square foot per annum of
Additional  Premises (the  "Interim  Rent"),  pro-rated on a daily basis,  until
January 1, 2006.  Landlord  and Tenant shall  mutually  agree upon the number of
square feet that is subject to the Interim Rent.

      13.  Section  2(n)  of the  Lease  is  hereby  amended  to  provide  that,
commencing on June 1, 2005, the Base Year for the Premises shall be the calendar
year 2006.


                                       3
<PAGE>

      14.  Section  2(p) of the  Lease is hereby  amended  to  provide  that the
Property Management  Company/Address is: Cushman & Wakefield, 125 Summer Street,
Boston, Massachusetts 02110, Attention: Julia Arsenault.

      15. Section 2(q) of the Lease is hereby amended to provide that Landlord's
Broker is Cushman & Wakefield, 125 Summer Street, Boston, Massachusetts 02110.

      16.  Section 2(r) of the Lease is hereby  amended to provide that Tenant's
Broker is Bayshore  Partners,  469 South  Glassell  Street,  Orange,  California
92866.

      17. Section 2(s) of the Lease is hereby amended to add the following:

      "Lease Month" shall mean each  consecutive  calendar  month period thereof
      during the Term,  with the first Lease Month  commencing on the Additional
      Premises Rent Commencement Date;  however, if the Additional Premises Rent
      Commencement  Date  falls on a day other  than the first day of a calendar
      month,  the first Lease Month shall commence on the first day of the month
      following the Additional  Premises Rent Commencement Date and Tenant shall
      pay  Landlord  Rent on a per diem basis on the  Additional  Premises  Rent
      Commencement  Date for the period  between the  Additional  Premises  Rent
      Commencement Date and the first Lease Month."

      18.  Section  2(t) of the  Lease is hereby  deleted  in its  entirety  and
replaced with the following:

      Tenant's  Electricity  Share:  100%,  which is the percentage  obtained by
      dividing  (i) the  total  square  feet of the  Premises  by (ii) the total
      rentable  square  feet of floor  area on the third  (3rd) and fifth  (5th)
      floors of the Building.

      19.  Section  2(u) of the  Lease is hereby  deleted  in its  entirety  and
replaced with the following:

      Extension Period: Two (2) additional periods of five (5) years each.

      20. The following is hereby added as Section 2(w) to the Lease:

      Parking:  Tenant, at no cost to Tenant, shall have the non-exclusive right
      to use up to 3.5 parking  spaces for every 1,000  rentable  square feet of
      Premises in the parking  facilities,  at no cost to Tenant. All parking is
      available on a first come-first serve basis provided, however, that in the
      event  Landlord  offers  reserve  parking to any  tenant in the  Building,
      Tenant shall also be entitled to a proportional number of reserved parking
      spaces based upon rentable square feet of premises.


                                       4
<PAGE>

      21.  Section  6(d) of the Lease is hereby  deleted in its  entirety and is
replaced with the following:

      Electricity Charge. Tenant, promptly upon being billed therefor, shall pay
      to Landlord,  as Additional Rent, Tenant's  Electricity Share of the total
      electricity  charge  for the third  (3rd) and  fifth  (5th)  floors of the
      Building  in  accordance  with the  terms of such  bill.  All  electricity
      supplied to the third (3rd) and fifth (5th) floors is separately metered.

      22.  Section  7 of the  Lease is  hereby  deleted  and  replaced  with the
following:


                                       5
<PAGE>

            7.    SECURITY DEPOSIT.

      To  secure  the full and  faithful  performance  by  Tenant  of all of the
covenants,  conditions and agreements set forth in this Lease to be performed by
it, including, without limitation, the foregoing such covenants,  conditions and
agreements  in this  Lease  which  become  applicable  upon its  termination  by
re-entry or otherwise, Tenant has deposited with Landlord the sum of Two Hundred
Twenty-Five  Thousand Dollars  ($225,000.00),  subject to adjustment as provided
herein (the "Security Deposit") on the understanding:

            (a) that the Security  Deposit or any portion thereof may be applied
            to the  curing of any  default  that may  exist,  including  but not
            limited to a breach for failure to pay Rent,  without  prejudice  to
            any other  remedy or  remedies  which  Landlord  may have on account
            thereof,  and upon such  application  Tenant  shall pay  Landlord on
            demand the amount so applied  which  shall be added to the  Security
            Deposit so the same will be restored to its original amount;

            (b) that should the Premises be conveyed by  Landlord,  the Security
            Deposit  or  any  balance  thereof  shall  be  turned  over  to  the
            Landlord's  grantee,  and if the Security  Deposit is turned over to
            such  grantee,  Tenant  hereby  releases  Landlord  from any and all
            liability with respect to the Security  Deposit and its  application
            or return, and Tenant agrees to look solely to such grantee for such
            application or return;

            (c) that  Landlord may  commingle  the  Security  Deposit with other
            funds,  shall not be required to keep the Security Deposit in trust,
            and shall not be obligated to pay Tenant any interest;

            (d) that the Security  Deposit  shall not be  considered  an advance
            payment of Rent or a measure of damages  for any  default by Tenant,
            nor shall it be a bar or defense to any actions by Landlord  against
            Tenant;

            (e) that if Tenant shall faithfully perform all of the covenants and
            agreements  contained  in this Lease on the part of the Tenant to be
            performed, and provided there exists no default by Tenant hereunder,
            the Security Deposit or any then remaining balance thereof, shall be
            returned to Tenant, without interest,  within thirty (30) days after
            the  expiration  of  the  Term,  provided  that  subsequent  to  the
            expiration  of this Lease,  Landlord  may retain  from the  Security
            Deposit  (i) an amount  reasonably  estimated  by  Landlord to cover
            potential Operating Expense reconciliation payments due with respect
            to the calendar year in which this Lease terminates or expires (such
            amount so retained


                                       6
<PAGE>

            shall not,  in any  event,  exceed ten  percent  (10%) of  estimated
            Operating  Expense  payments due from Tenant for such  calendar year
            through the date of expiration or earlier  termination of this Lease
            and any amounts so retained  and not applied to such  reconciliation
            shall be returned to Tenant within thirty (30) days after Landlord's
            delivery of the Statement for such calendar year), (ii) in the event
            Tenant fails to remove any signage  required to be removed by Tenant
            pursuant to this Lease, any and all amounts reasonably  estimated by
            Landlord to cover the  anticipated  costs to be incurred by Landlord
            to remove any  signage  provided  to Tenant  under this Lease and to
            repair any damage  caused by such  removal (in which case any excess
            amount so retained by  Landlord  shall be returned to Tenant  within
            thirty (30) days after such removal and  repair),  and (iii) any and
            all amounts permitted by law or this Article 7. Tenant hereby waives
            any and all  provisions  of law,  now or  hereafter in effect in the
            State in which the  Building  is  located  or any  local  government
            authority or agency or any political subdivision thereof, that limit
            the types of  defaults  for which a  landlord  may claim sums from a
            security deposit,  it being agreed that Landlord,  in addition,  may
            claim those sums  specified in this Article7 above and/or those sums
            reasonably  necessary to  compensate  Landlord for any other loss or
            damage  caused by the acts or  omissions  of Tenant or any  officer,
            employee,  agent,  contractor or invitee of Tenant.  Tenant  further
            covenants  that it will not assign or encumber  the money  deposited
            herein as a  Security  Deposit  and that  neither  Landlord  nor its
            successors  or  assigns  shall  be  bound  by any  such  assignment,
            encumbrance, attempted assignment or attempted encumbrance.

            (f) the  Security  Deposit may be in the form of a letter of credit.
            In such event,  Tenant,  simultaneously  with the  execution of this
            Lease,  shall  deliver to Landlord (as  beneficiary),  and a copy to
            Landlord's   attorney,  a  standby  letter  of  credit  ("Letter  of
            Credit"),  in form and content satisfactory to Landlord.  The Letter
            of Credit shall be, among other things:

                  (1)   subject  to   International   Standby   Practices  1998,
                        International Chamber of Commerce Publication No. 590;

                  (2)   irrevocable and unconditional;

                  (3)   in the amount of the required Security Deposit;

                  (4)   conditioned for payment solely upon  presentation of the
                        Letter of Credit  and a sight  draft  certifying  to the
                        issuer of the  Letter of Credit  the  existence  of such
                        grounds  or   circumstances   upon  which   Landlord  is
                        permitted to make such draw, and


                                       7
<PAGE>

                  (5)   transferable  one or more times by Landlord  without the
                        consent of Tenant.

                  Tenant   acknowledges  and  agrees  that  it  shall  pay  upon
      Landlord's  demand,  as Additional Rent, any and all costs or fees charged
      in connection  with the Letter of Credit that arise due to: (i) Landlord's
      sale  or  transfer  of all or a  portion  of the  Property,  or  (ii)  the
      addition,  deletion, or modification of any beneficiaries under the Letter
      of  Credit.  The  Letter of Credit  shall be issued by a member of the New
      York  Clearing  House  Association  or a commercial  bank or trust company
      satisfactory  to Landlord,  having banking  offices at which the Letter of
      Credit may be drawn upon in New  Hampshire,  Massachusetts  or Connecticut
      and a net worth  reasonably  acceptable to Landlord.  The Letter of Credit
      shall expire not earlier than 12 months after the date of delivery thereof
      to Landlord and shall provide that same shall be automatically renewed for
      successive  12 month  periods  through a date which is not earlier than 60
      days after the  expiration  date,  or any  renewal or  extension  thereof,
      unless written notice of non-renewal has been given by the issuing bank to
      Landlord and Landlord's  attorney by registered or certified mail,  return
      receipt  requested,  not less than 60 days prior to the  expiration of the
      current  period.  If the issuing bank does not renew the Letter of Credit,
      and if Tenant  does not deliver a  substitute  Letter of Credit or cash in
      lieu  thereof  at least 30 days  prior to the  expiration  of the  current
      period, then in addition to its rights granted under this Lease,  Landlord
      shall have the right to draw on the existing Letter of Credit and maintain
      such funds as a cash security deposit. With respect to draws on the Letter
      of Credit:

                  (x)   Landlord may use,  apply,  or retain the proceeds of the
                        Letter of Credit to the same  extent that  Landlord  may
                        use, apply, or retain the cash Security Deposit,  as set
                        forth above in this Section or elsewhere in this Lease;

                  (y)   Landlord  may draw on the Letter of Credit,  in whole or
                        in part, from time to time, at Landlord's  election,  to
                        the  same  extent  that  Landlord  may  draw on the cash
                        Security Deposit,  as set forth above in this Section or
                        elsewhere in this Lease; and

                  (z)   If Landlord  partially  draws down the Letter of Credit,
                        Tenant shall within ten (10) days after  Landlord  gives
                        Tenant  notice  thereof,  restore all  amounts  drawn by
                        Landlord, or substitute cash security instead.

                  Tenant  hereby  agrees  to  cooperate,  at  its  expense  with
      Landlord  to  promptly  execute  and  deliver  to  Landlord  any  and  all
      modifications, amendments and replacements of the Letter of Credit,


                                       8
<PAGE>

      as Landlord may  reasonably  request to carry out the terms and conditions
      of this Section.

                  Notwithstanding  anything  set  forth  in  this  Lease  to the
      contrary,  provided  that no more  than one (1)  monetary  default  beyond
      applicable  cure  periods has  occurred in any Lease Year and  provided no
      Event of Default has occurred and is continuing, Landlord shall (a) refund
      $75,000.00  of the  Security  Deposit if the same is  provided  in cash to
      Tenant or allow  Tenant to replace  the Letter of Credit  with a Letter of
      Credit in the amount of  $150,000.00  on or about July 1, 2007, (b) refund
      an additional  $50,000.00 of the Security  Deposit if the same is provided
      in cash to Tenant or allow  Tenant to replace  the Letter of Credit with a
      Letter of Credit in the amount of $100,000.00 on or about July 1, 2008 and
      (c) refund an additional $50,000.00 of the Security Deposit if the same is
      provided in cash to Tenant or allow Tenant to replace the Letter of Credit
      with a Letter of Credit in the amount of  $50,000.00  on or about March 1,
      2011. The remainder of such security deposit or such replacement Letter of
      Credit,  from time to time,  shall be  subject to the  provisions  of this
      Article 7.

      23.  Section 9 of the  Lease is  hereby  deleted  in its  entirety  and is
replaced with the following:

            9. DELIVERY OF ADDITIONAL PREMISES TO TENANT;  TENANT  IMPROVEMENTS.
            Landlord  shall  deliver  the  Additional   Premises  to  Tenant  in
            accordance with the following schedule:

            Suites 301 (5,102 square feet) and 304 (2,249  square  feet):  three
            (3) business days after the full  execution of the Fourth  Amendment
            to Lease.

            Suites 302 (3,349 square feet) and 303 (2,708 square feet):  October
            1, 2005, subject to extension as provided below.

            On  and  after  the  dates  specified  above  for  delivery  of  the
            Additional  Premises to Tenant,  Tenant agrees to commence  Tenant's
            Work (as  hereinafter  defined)  and shall  perform and complete all
            improvements to the Additional Premises and to the Original Premises
            (herein called "Tenant's Work")  including,  but not limited to, all
            improvements,  work and  requirements  required of Tenant  under the
            work letter  attached hereto as Exhibit E. Tenant shall complete all
            of Tenant's Work in good and workmanlike manner,  fully paid for and
            free from liens,  in  accordance  with the plans and  specifications
            approved  by  Landlord  and Tenant as  provided  in Exhibit E, on or
            prior to January 1, 2006.  Tenant  shall also have the right  during
            this  period to come onto the  Additional  Premises  to install  its
            fixtures and prepare the  Additional  Premises for the  operation of
            Tenant's business. Notwithstanding the fact that the


                                       9
<PAGE>

            foregoing  activities may occur prior to the Rent Commencement Date,
            Tenant agrees that all of Tenant's  obligations provided for in this
            Lease shall apply during any such period,  with the exception of any
            obligation  to pay Rent for the  Additional  Premises.  In the event
            that  Suites 302 or 303 are not  delivered  on or before  October 1,
            2005,  Landlord  shall have an  additional  ninety  (90) days within
            which to deliver said premises and (i) the date upon which Base Rent
            shall  commence and (ii) the expiration  date of the term,  shall be
            delayed  by the  number  of days  equal  to the  difference  between
            October 1, 2005 and the actual date of delivery of said  premises to
            Tenant. In the event that Suites 302 or 303 are not delivered within
            ninety (90) days of October 1, 2005 (the "Outside  Delivery  Date"),
            Tenant  shall  receive  one day of  free  Monthly  Base  Rent on the
            undelivered  suite(s) for each day between the Outside Delivery Date
            and the date of actual delivery.

      24. The Lease is hereby  amended to substitute  Exhibit C attached  hereto
for Exhibit E to the Lease.

      25. The  following  paragraphs  are  hereby  added to and made part of the
Lease:

            29.   Options to Extend Term

                  (a)  Tenant  shall  have and is hereby  granted  the option to
            extend the Term  hereof for two (2)  additional  periods of five (5)
            years (the  "Extension  Period"),  provided (i) Tenant gives written
            notice to Landlord of Tenant's election of interest to exercise such
            extension  option no earlier  than fifteen  (15),  and no later than
            twelve (12) months,  prior to the  expiration of the last Lease Year
            of the  Term;  and (ii) no  event of  default  has  occurred  and is
            continuing  at the time of the  exercise  of such  option  or arises
            subsequent thereto, which event by notice and/or the passage of time
            would  constitute  a  default  by Tenant  if not  cured  within  the
            applicable cure period.

                  (b) All terms and conditions of this Lease,  including without
            limitation all provisions  governing the payment of Additional Rent,
            shall remain in full force and effect during the  Extension  Period,
            except that no Construction  Allowance shall be provided and Monthly
            Base  Rent  payable  during  the  Extension  Period(s)  shall be the
            then-current  fair  market  rental  rate for  renewal  tenants  with
            respect to  comparable  office  space at the time of the exercise of
            the option granted  herein,  taking into account market  concessions
            for renewals of existing  leases in office  buildings  comparable to
            the Building,  but in no event less than the fully escalated Monthly
            Base Rent, Operating Expenses


                                       10
<PAGE>

            and Taxes in effect for the last Lease Year of the Term (the "Option
            Rental  Rate")  and the Base Year for Taxes and  Operating  Expenses
            shall be the calendar year in which the Extension Period commences.

                  (c) Landlord shall provide Tenant notice of its  determination
            of the Option  Rental Rate  within  fifteen  (15) days after  Tenant
            provides its written notice of interest to extend. Tenant shall have
            thirty (30) days from receipt of Landlord's  determination to either
            (1) extend the Term of this Lease,  (2) elect not to extend the Term
            of this  Lease or (3)  elect  to  extend  the Term of this  Lease in
            accordance  with the provisions of  subparagraph  (d) below.  In the
            event  Tenant  fails to elect  any of the  aforementioned  three (3)
            options  within said 30-day  period,  Tenant shall be deemed to have
            elected option (2).

                  (d) In the event Tenant  shall elect option 3 in  subparagraph
            (c) above,  Landlord  and Tenant  shall  negotiate  in good faith to
            arrive at a  mutually-agreeable  Monthly Base Rent for the Extension
            Period,  for a period  of thirty  (30) days  after the date on which
            Landlord  receives  Tenant's  written  notice of  Tenant's  election
            pursuant to the preceding sentence. In the event Landlord and Tenant
            are unable to agree upon the  Monthly  Base Rent for such  Extension
            Period within said thirty (30)-day period, then within five (5) days
            thereafter,  Landlord and Tenant shall each simultaneously submit to
            the other in a sealed envelope its good faith estimate of the Option
            Rental  Rate.  If the higher of such  estimates is not more than one
            hundred five percent (105%) of the lower of such estimates, then the
            Option Rental Rate shall be the average of the two estimates. If the
            matter is not resolved by the exchange of estimates, then the Option
            Rental Rate shall be  determined  as follows:  each of Landlord  and
            Tenant shall select a licensed real estate  broker,  and the two (2)
            brokers so selected shall jointly select a third (3rd) broker.  Each
            broker so selected  shall be licensed in the State of New  Hampshire
            as a real  estate  broker  specializing  in the field of  commercial
            office  leasing in the Nashua,  New Hampshire  area,  having no less
            than ten (10) years'  experience in such field.  Landlord and Tenant
            agree to make their appointments promptly within ten (10) days after
            the expiration of the thirty  (30)-day  period or sooner if mutually
            agreed  upon.  The two (2) brokers  selected by Landlord  and Tenant
            shall  promptly  select the third (3rd) broker  within ten (10) days
            after they both have been appointed.  Once the third broker has been
            selected  as  provided  for  above,  then,  as  soon  thereafter  as
            practicable,  but in any case within fourteen (14) days after his or
            her appointment,  said broker shall determine the Option Rental Rate
            by selecting either the Landlord's estimate of Option Rental Rate or
            the  Tenant's  estimate  of Option  Rental  Rate.  There shall be no
            discovery or similar proceedings. The broker's decision as


                                       11
<PAGE>

            to which  estimate of Option  Rental Rate shall be the Option Rental
            Rate for the  Extended  Term  shall be  rendered  in writing to both
            Landlord  and  Tenant and shall be final and  binding  upon them and
            shall be the Base Rent for the  Extension  Period.  The costs of the
            broker will be equally divided between Landlord and Tenant. Any fees
            of any  counsel  engaged by Landlord  or Tenant,  however,  shall be
            borne by the party that retained such counsel.

                  (e) The parties  shall  execute an  amendment  modifying  this
            Lease to set forth the Monthly Base Rent for the Premises during the
            Extension Period within ten (10) days of the parties'  agreement or,
            in  the   alternative,   within  ten  (10)  days  of  the   brokers'
            determination, of the Monthly Base Rent for the Extension Period.

            30.   Right of First Offer

                  A.  During  the  period  commencing  on the  date  hereof  and
            continuing  until the  expiration of the initial Term of this Lease,
            provided  that this  Lease is in full  force and  effect and that no
            default  shall  exist  under  this  Lease  (both  at the time of the
            exercise of the right(s)  described  herein and on the date of entry
            into the  agreement  incorporating  the Offer Space (as  hereinafter
            defined),  Tenant shall have the right at the expiration of the term
            of any lease in respect  of the Offer  Space,  (the  "Right of First
            Offer")  to lease all or any  portion of the  Building  on the first
            occasion  that such area "becomes  available".  For purposes of this
            Section,  Offer Space shall be deemed to "become available" when the
            lease or other occupancy  agreement for the current  occupant of the
            space expires or is otherwise terminated.

                  B.  Notwithstanding  anything set forth in this Section to the
            contrary,  Offer Space shall not be deemed to "become  available" if
            the space is:

            (i) Assigned or subleased by the current tenant of the space; or

            (ii)  Re-leased  by the  current  tenant  of the  space by  renewal,
            extension,  or  renegotiation  (whether  or not an  express  renewal
            option is afforded to such tenant under the terms of its lease); or

            (iii) Not  leased to a tenant  as of the date of this  Lease  (until
            that space is leased, and then subsequently "becomes available"); or


                                       12
<PAGE>

            (iv) Subject to an existing  right of first offer of another  tenant
            in the Building.

                  Subject to the  foregoing,  at such time as all or any portion
            of the Building  becomes  available  (the "Offer  Space"),  Landlord
            shall  furnish  to Tenant a notice  (the  "First  Offer  Proposal").
            Tenant  shall have the option,  exercisable  by notice  delivered to
            Landlord  within ten (10)  business days after  Tenant's  receipt or
            refusal of receipt of Landlord's First Offer Proposal, TIME BEING OF
            THE ESSENCE,  to notify  Landlord that it is interested in the Offer
            Space.  If Tenant  timely  delivers  to Landlord  written  notice of
            Tenant's  exercise of the Right of First Offer for the Offer  Space,
            then  Landlord  and tenant shall have twenty (20)  business  days to
            negotiate and agree upon a letter of intent for said Offer Space and
            an  additional  ten  (10)  business  days to  enter  into a  binding
            amendment  memorializing  the same  (said 20 - and 10 - day  periods
            hereinafter  collectively referred to as the "Negotiation  Period").
            If Tenant  declines or fails to timely  exercise  its Right of First
            Offer or if either the letter of intent or the amendment referred to
            in the  immediately  preceding  sentence  is not  timely  completed,
            Landlord  shall  thereafter be free to lease the Offer Space without
            regard to the  restrictions  contained  herein and on such terms and
            conditions as Landlord may decide in its sole  discretion  provided,
            however, that Landlord shall not lease the Offer Space for less than
            90  percent  of the  rent  specified  in  Landlord's  final  written
            proposal during the Negotiation  Period. The Right of First Offer is
            only available to Tenant upon the occasion that Offer Space "becomes
            available"  and Tenant  recognizes  and agrees that it shall have no
            further  right to lease such Offer Space until it once again becomes
            available, subject to the terms hereof.

                  C. This Right of First  Offer is  personal to Tenant and shall
            become null and void upon the  occurrence  of an  assignment  of the
            Lease  or  subletting  of all  or any  portion  of the  Premises  in
            accordance  with the terms of this  Lease  other than  transfers  to
            companies affiliated with Tenant, its parent corporation, successors
            by merger or  purchasers  of all or  substantially  all of  Tenant's
            assets.

                  D. Notwithstanding  anything contained to the contrary herein,
            in the event  Tenant  elects to exercise the Right of First Offer at
            any time during the last three (3) years of the initial term of this
            Lease,  such exercise  shall also  constitute  Tenant's  election to
            exercise its first  Extension  option  pursuant to Section 29 herein
            without any  further  action  required.  In the event that the First
            Offer  Proposal  is  furnished  to Tenant  during the last three (3)
            years of the initial term of this Lease,  said First Offer  Proposal
            shall contain the following statement: "PLEASE BE


                                       13
<PAGE>

            ADVISED THAT  TENANT'S  EXERCISE OF THIS RIGHT OF FIRST OFFER SHALL,
            WITHOUT ANY FURTHER ACTION, CONSTITUTE TENANT'S ELECTION TO EXERCISE
            ITS FIRST EXTENSION OPTION PURSUANT TO SECTION 29 OF THE LEASE."

                  31.  Parking.  (a) Landlord hereby grants to Tenant the right,
            in common with others  authorized  by  Landlord,  to use the parking
            facilities  appurtenant to the Building,  if any, and to use no more
            than the number of parking  spaces made  available  to Tenant as set
            forth  in  Section  2(w)  notwithstanding  the  number  of  Tenant's
            employees,  customers or invitees. Landlord shall have the right, at
            Landlord's   sole   election,   to   change   said   types,   sizes,
            configuration,  and locations from time to time; provided,  however,
            such designation  shall be uniformly  applied and shall not unfairly
            favor any tenant in the Building.

                  (b) If requested by Landlord,  Tenant shall notify Landlord of
            the license plate number,  year,  make and model of the  automobiles
            entitled to use the parking facilities and if requested by Landlord,
            such automobiles  shall be identified by automobile  window stickers
            provided by Landlord,  and only such designated automobiles shall be
            permitted  to  use  the  parking  facilities.   At  Landlord's  sole
            election,  Landlord may make validation stickers available to Tenant
            for any  such  additional  parking  spaces,  provided,  however,  if
            Landlord makes validation  stickers available to any other tenant in
            the Building, Landlord shall make such validation stickers available
            to  Tenant.  In the event  Tenant  exceeds  the  number of  allotted
            parking  spaces  set  forth  in  Section  2(w)  or if  Landlord  has
            instituted a window sticker or other parking  procedure and Tenant's
            employees,  customers  or  invitees  do not  comply  with  any  such
            procedure,  then in any of such events,  Landlord  shall be entitled
            to,  without any liability to Tenant,  its  employees,  customers or
            invitees,   remove  any  vehicles  not  complying  with   Landlord's
            procedures or parking in excess of such  allotted  number of spaces.
            Tenant  acknowledges and agrees that Landlord may, without incurring
            any liability to Tenant and without any abatement of Rent under this
            Lease,  from  time to time,  close-off  or  restrict  access  to the
            parking   facility  for  purposes  of  permitting  or   facilitating
            construction,  alteration or improvement  provided Landlord provides
            reasonably  adequate  substitute  parking in the event said  actions
            unreasonably  interfere  with Tenant's  parking  privileges  granted
            herein.  Landlord may delegate its  responsibilities  hereunder to a
            parking  operator or a lessee of the parking  facility in which case
            such parking operator or lessee shall have all the rights of control
            attributed hereby to the Landlord.


                                       14
<PAGE>

                  (c) Tenant may not assign,  transfer,  sublease  or  otherwise
            alienate the use of the parking  facilities without Landlord's prior
            written consent.

                  32.   Anti-Terrorism Representation.

                  (1)   Tenant certifies that:

                        (a) It is not acting, directly or indirectly,  for or on
behalf of any person,  group,  entity, or nation named by any Executive Order or
the United  States  Treasury  Department as a terrorist,  "Specially  Designated
National and Blocked Person," or other banned or blocked person, entity, nation,
or transaction  pursuant to any law, order, rule, or regulation that is enforced
or administered by the Office of Foreign Assets Control; and

                        (b) It is not engaged in this  transaction,  directly or
indirectly  on behalf  of, or  instigating  or  facilitating  this  transaction,
directly or indirectly on behalf of, any such person, group, entity, or nation.

                  (2)  Tenant  hereby  agrees  to  defend,  indemnify,  and hold
harmless Landlord from and against any and all claims,  damages,  losses, risks,
liabilities,  and expenses (including attorney's fees and costs) arising from or
related to any breach of the foregoing certification.

                  33.   ERISA Representation.

      Tenant will not use the assets of an employee  benefit  plan as defined in
Section 3(3) of the Employee  Retirement Income Security Act of 1974, as amended
("ERISA")  and  covered  under  Title I, Part 4 of ERISA or Section  4975 of the
Internal  Revenue Code of 1986,  as amended,  in the  performance,  discharge or
satisfaction  of any of its  obligations  under  this  Lease  such that it would
constitute a "prohibited  transaction" under ERISA.  Tenant shall not assign its
interest  hereunder to any person or entity which does not  expressly  make this
covenant and warranty for the benefit of Landlord.

      26.  Relocation  of  Ameriquest  Mortgage  Company,   Key  Commerce,   and
Hewlett-Packard. Landlord and Tenant hereby acknowledge that Ameriquest Mortgage
Company,  Key  Commerce  and  Hewlett-Packard  (collectively,   the  "Relocation
Tenants")  currently occupy the Additional  Premises and need to be relocated to
other  premises  within  the  Building.   Landlord  and  Tenant  hereby  further
acknowledge  that Landlord will be solely  responsible for, and Tenant will have
no obligation to contribute to, the cost of such relocations.  In the event that
Landlord has not procured agreements with the Relocation  Tenants,  satisfactory
to Landlord, in its sole and absolute discretion, to accomplish the foregoing on
or before  October 1, 2005,  Landlord or Tenant  shall have the right to declare
this  Amendment  terminated and of no further force or effect upon notice to the
other.


                                       15
<PAGE>

      27. Lease Guaranty.  Tenant  acknowledges that as a material inducement to
Landlord  to enter  into this  Amendment,  Tenant  shall  deliver  to  Landlord,
simultaneously with execution of this Amendment by Tenant, the unconditional and
unlimited guaranty by Curative Health Services, Inc. ("Guarantor") of all of the
obligations  of Tenant under the Lease,  the form of which  guaranty is attached
hereto as  Exhibit D and made a part  hereof  (the  "Guaranty").  It shall be an
Event of Default by Tenant under the Lease,  if the Guaranty  does not remain in
full  force  and  effect  throughout  the Term of the Lease or in the event of a
breach of any of the  obligations of Guarantor  under the Guaranty,  without the
necessity of notice by Landlord to Tenant or any other action by Landlord.

      IN WITNESS  WHEREOF,  the parties have executed  this Fourth  Amendment to
Lease as of the day and year first above written.

                                       LANDLORD:

                                       BROOKHAVEN (NASHUA), LLC,
                                       a Delaware limited liability company

                                       By: CORNERSTONE REAL ESTATE
                                           ADVISERS LLC,
                                           its authorized agent

                                       By:   /s/ David M. Romano
                                             ------------------------------

                                       Name:  David M. Romano
                                              -----------------------------

                                       Title: Vice President
                                              -----------------------------

                                       Date:  8/26/05
                                              -----------------------------


                                       16
<PAGE>

                                       TENANT:

                                       CRITICAL CARE SYSTEMS, INC.,
                                       a Delaware corporation

                                       By:    /s/ John C. Prior
                                              -----------------------------

                                       Name:  John C. Prior
                                              -----------------------------

                                       Title: C.O.O.
                                              -----------------------------

                                       Date:  7/18/05
                                              -----------------------------


                                       17
<PAGE>

                                    EXHIBIT A

                               Additional Premises


                                      A-1
<PAGE>

                                    EXHIBIT B

                                  The Premises


                                      B-1
<PAGE>

                                    EXHIBIT C

                              Tenant's Work Letter

This Tenant Work Letter shall set forth the terms and conditions relating to the
renovation of the tenant  improvements in the Premises.  This Tenant Work Letter
is  essentially  organized  chronologically  and  addresses  the  issues  of the
renovation of the Premises, in sequence, as such issues will arise.

                                    SECTION 1

                 LANDLORD'S INITIAL CONSTRUCTION IN THE PREMISES

Landlord has constructed, at its sole cost and expense, the base, shell and core
(i) of the Premises, and (ii) of the floor of the Building on which the Premises
is located (collectively,  the "Base, Shell and Core"). Tenant has inspected and
hereby  approves the condition of the Base,  Shell and Core, and agrees that the
Base,  Shell  and Core  shall be  delivered  to Tenant  in its  current  "as-is"
condition.  The improvements to be initially  installed in the Premises shall be
designed  and  constructed  pursuant to this Tenant  Work  Letter.  Any costs of
initial design and  construction of any  improvements to the Premises shall be a
"Construction  Allowance  Item",  as that term is defined in Section 2.2 of this
Tenant Work Letter.

                                    SECTION 2

                                  IMPROVEMENTS

      2.1  Construction  Allowance.  Tenant  shall  be  entitled  to a  one-time
improvement  allowance  (the  "Construction  Allowance")  in the  amount of FOUR
HUNDRED FIFTY THOUSAND AND 00/100  ($450,000.00)  DOLLARS for the costs relating
to the  initial  design and  construction  of  Tenant's  improvements  which are
permanently  affixed to the Premises  (the "Tenant  Improvements").  In no event
shall Landlord be obligated to make  disbursements  pursuant to this Tenant Work
Letter in a total  amount which  exceeds the  Construction  Allowance  and in no
event  shall  Tenant be  entitled  to any credit  for any unused  portion of the
Construction  Allowance not used by Tenant within ninety (90) days following the
Additional Premises Rent Commencement Date.

      2.2 Disbursement of the Improvement  Allowance.  Subject to the conditions
of Section 6.4 and except as otherwise set forth in this Tenant Work Letter, the
Construction   Allowance   shall  be  disbursed  by  Landlord   (each  of  which
disbursements  shall be made within  fifteen [15]  business days after a written
request for such  disbursement  has been submitted by Tenant to Landlord in form
and  substance  reasonably  satisfactory  to Landlord)  for costs related to the
construction  of  the  Improvements  and  for  the  following  items  and  costs
(collectively,  the "Construction  Allowance Items"): (i) payment of the fees of
the "Architect"  and the  "Engineers," as those terms are defined in Section 3.1
of this Tenant Work Letter, and payment of the reasonable fees incurred by, and


                                      C-1
<PAGE>

the  reasonable  cost of  documents  and  materials  supplied  by,  Landlord and
Landlord's  consultants  in connection  with the  preparation  and review of the
"Construction  Drawings,"  as that term is defined in Section 3.1 of this Tenant
Work Letter;  (ii) the cost of permits,  construction  supervision  fees and the
cost of installing  data and voice cabling  throughout  the Premises;  (iii) the
cost of any changes in the Base,  Shell and Core  required  by the  Construction
Drawings;  and (iv) the cost of any  changes  to the  Construction  Drawings  or
Tenant Improvements required by applicable building codes (the "Code"). However,
in no event shall more than Three and 00/100  Dollars  ($3.00) per usable square
foot of the  Construction  Allowance be used for the items  described in (i) and
(ii) above;  any  additional  amount  incurred as a result of (i) and (ii) above
shall be deemed to constitute an Over-Allowance Amount.

2.3 Standard Improvement Package.  Landlord has established  specifications (the
"Specifications")  for  the  Building  standard  components  to be  used  in the
construction  of the Tenant  Improvements  in the  Premises  (collectively,  the
"Standard  Improvement  Package"),   which  Specifications  are  available  upon
request.  The  quality  of Tenant  Improvements  shall be equal to or of greater
quality than the quality of the  Specifications,  provided that Landlord may, at
Landlord's  option,  require  the Tenant  Improvements  to comply  with  certain
Specifications.

                                    SECTION 3

                              CONSTRUCTION DRAWINGS

3.1  Selection  of  Architect/Construction  Drawings.  Tenant  shall  retain  an
architect/space  planner designated by Landlord (the "Architect") to prepare the
"Construction  Drawings,"  as that term is defined in this Section  3.1.  Tenant
shall also  retain the  engineering  consultants  designated  by  Landlord  (the
"Engineers") to prepare all plans and engineering  working drawings  relating to
the structural,  mechanical,  electrical,  plumbing, HVAC and lifesafety work of
the Tenant Improvements.  The plans and drawings to be prepared by Architect and
the  Engineers  hereunder  shall  be  known  collectively  as the  "Construction
Drawings."  All  Construction  Drawings shall comply with the drawing format and
specifications  as reasonably  determined  by Landlord,  and shall be subject to
Landlord's reasonable approval. Tenant and Architect shall verify, in the field,
the  dimensions  and  conditions  as shown on the relevant  portions of the base
building  plans,  and Tenant and Architect  shall be solely  responsible for the
same,  and  Landlord  shall  have no  responsibility  in  connection  therewith.
Landlord's  review of the Construction  Drawings as set forth in this Section 3,
shall be for its sole purpose and shall not imply Landlord's review of the same,
or obligate Landlord to review the same, for quality, design, Code compliance or
other like matters. Accordingly,  notwithstanding that any Construction Drawings
are  reviewed  by  Landlord  or its  space  planner,  architect,  engineers  and
consultants,  and notwithstanding any advice or assistance which may be rendered
to Tenant by Landlord or Landlord's  space planner,  architect,  engineers,  and
consultants, Landlord shall have no liability whatsoever in connection therewith
and shall not be  responsible  for any  omissions  or  errors  contained  in the
Construction Drawings.


                                      C-2
<PAGE>

3.2 Final  Space Plan.  On or before the date set forth in Schedule 1,  attached
hereto,  Tenant and the  Architect  shall  prepare  the final space plan for the
Tenant  Improvements  in the Premises  (collectively,  the "Final Space  Plan"),
which Final Space Plan shall  include a layout and  designation  of all offices,
rooms and other partitioning,  their intended use, and equipment to be contained
therein,  and shall  deliver  the Final Space Plan to  Landlord  for  Landlord's
reasonable approval.

3.3 Final  Working  Drawings.  On or before  the date set forth in  Schedule  1,
Tenant,  the Architect and the Engineers  shall complete the  architectural  and
engineering  drawings  for the  Premises,  and the final  architectural  working
drawings in a form which is complete to allow  subcontractors to bid on the work
and  to  obtain  all  applicable  permits  (collectively,   the  "Final  Working
Drawings")  and shall  submit the same to  Landlord  for  Landlord's  reasonable
approval.

3.4  Permits.  The Final  Working  Drawings  shall be approved by Landlord  (the
"Approved  Working  Drawings")  prior to the commencement of the construction of
the Tenant Improvements.  Tenant shall cause the Architect to immediately submit
the Approved Working Drawings to the appropriate  municipal  authorities for all
applicable  building  permits  necessary to allow  "Contractor," as that term is
defined in Section 4.1, below,  to commence and fully complete the  construction
of the  Tenant  Improvements  (the  "Permits").  No  changes,  modifications  or
alterations  in the  Approved  Working  Drawings  may be made  without the prior
written consent of Landlord, which consent shall not be unreasonably withheld.

3.5 Time Deadlines.  Tenant and Landlord shall use their  respective  best, good
faith  efforts and all due  diligence to cooperate  with the  Architect  and the
Engineers to complete all phases of the Construction Drawings and the permitting
process and to receive the  permits,  and with  Contractor  for  approval of the
"Cost  Proposal,"  as that term is defined in Section  4.2 of this  Tenant  Work
Letter,  as soon as  possible  after the  execution  of the Lease,  and, in that
regard,  Landlord  and Tenant  shall  meet on a  scheduled  basis as  reasonably
necessary to discuss  their  respective  obligations  and progress in connection
with the same. The applicable dates for approval of items, plans and drawings as
described in this Section 3, Section 4 below, and in this Tenant Work Letter are
set forth and  further  elaborated  upon in  Schedule 1 (the "Time  Deadlines"),
attached hereto. Tenant and Landlord agree to comply with the Time Deadlines.

                                    SECTION 4

                        CONSTRUCTION OF THE IMPROVEMENTS

4.1 Contractor.  The contractor  which shall  construct the Tenant  Improvements
shall be a  contractor  designated  by Tenant  and  agreed to by  Landlord.  The
contractor selected may be referred to herein as the "Contractor".

4.2 Cost Proposal.  After the Approved  Working  Drawings are signed by Landlord
and Tenant,  Tenant shall  provide  Landlord  with a cost proposal in accordance
with the Approved Working Drawings, which cost proposal shall include, as nearly
as  possible,  the cost of all  Construction  Allowance  Items to be incurred by
Tenant in connection with the construction of the Tenant


                                      C-3
<PAGE>

Improvements (the "Cost  Proposal").  Landlord shall approve and return the Cost
Proposal to Tenant  within three (3)  business  days of the receipt of the same,
and upon  receipt of the same by  Tenant,  Tenant  and the  Contractor  shall be
released by Landlord to purchase the items set forth in the Cost Proposal and to
commence the  construction  relating to such items.  The date by which  Landlord
must approve and deliver the Cost Proposal to Tenant shall be known hereafter as
the "Cost Proposal Delivery Date".

4.3  Construction of Tenant  Improvements by Contractor under the Supervision of
Landlord.

                  4.3.1  Over-Allowance  Amount.  On the Cost Proposal  Delivery
Date, Tenant shall deliver to Landlord an amount (the  "Over-Allowance  Amount")
equal to the difference between (i) the amount of the Cost Proposal and (ii) the
amount of the Construction Allowance (less any portion thereof already disbursed
by Landlord,  or in the process of being disbursed by Landlord, on or before the
Cost Proposal Delivery Date). The Over-Allowance  Amount shall be held in escrow
by Landlord and shall be disbursed by Landlord subsequent to the disbursement of
the entire  Construction  Allowance.  Such disbursement shall be pursuant to the
same procedure as the Construction  Allowance. In the event that, after the Cost
Proposal Delivery Date, any revisions,  changes,  or substitutions shall be made
to the  Construction  Drawings or the Tenant  Improvements,  Tenant will deposit
with  Landlord  an amount  equal to any  estimated  additional  costs  which are
anticipated to arise in connection with such revisions, changes or substitutions
immediately  upon  acceptance of such  revisions,  changes or  substitutions  by
Landlord. Such additional  Over-Allowance Amount shall be held by Landlord as an
addition to the  Over-Allowance  Amount and  disbursed by Landlord in accordance
with this section 4.3. Within ten (10) days after Substantial  Completion of the
Tenant  Improvements,  satisfaction  of all punch list items,  and delivery of a
final  Mechanics Lien Waiver from the Contractor to the Landlord,  Landlord will
return to Tenant any portion of the Over-Allowance Amount remaining undisbursed.

                  4.3.2   Tenant's   Retention  of   Contractor.   Tenant  shall
independently   retain  Contractor  to  construct  the  Tenant  Improvements  in
accordance with the Approved  Working  Drawings and the Cost Proposal subject to
Landlord's prior approval of such Contractor.

                                    SECTION 5

                         COMPLETION OF THE IMPROVEMENTS

5.1 Substantial Completion. For purposes of this Lease, "Substantial Completion"
of the Tenant  Improvements  in the Premises  shall occur upon the completion of
construction of the Tenant Improvements in the Premises pursuant to the Approved
Working  Drawings,  with the  exception  of any punch  list items and any tenant
fixtures,  work-stations,  built-in  furniture,  or equipment to be installed by
Tenant.

5.2 Delay of the Substantial Completion of the Premises caused by Tenant. Except
as provided in this Section 5, the Commencement Date and Tenant's


                                      C-4
<PAGE>

obligation  to pay rent for the Premises  shall occur as set forth in the Lease.
However,  if  there  shall be a delay or there  are  delays  in the  Substantial
Completion  of the  Tenant  Improvements  in the  Premises  as a  result  of the
following (collectively, "Tenant Delays"):

                  5.2.1 Tenant's failure to comply with the Time Deadlines;

                  5.2.2 Tenant's  failure to timely approve any matter requiring
Tenant's approval;

                  5.2.3 A breach  by Tenant  of the  terms of this  Tenant  Work
Letter or the Lease;

                  5.2.4  Changes  in  any  of the  Construction  Drawings  after
disapproval of the same by Landlord  because the same do not comply with Code or
other applicable laws;

                  5.2.5  Tenant's  request for changes in the  Approved  Working
Drawings;

                  5.2.6  Tenant's  requirement  for  extra  ordinary  or  highly
specialized  materials,  components,  finishes  or  improvements,  which are not
available  in a  commercially  reasonable  time  given the  anticipated  date of
Substantial  Completion of the Tenant Improvements in the Premises and which are
different from, or not included in, the Standard Improvement Package; or

                  5.2.7 Any grossly  negligent or unreasonable acts or omissions
of Tenant, or its agents, or employees;

then,  notwithstanding  anything to the  contrary set forth in the Lease or this
Tenant  Work  Letter  and  regardless  of the  actual  date  of the  Substantial
Completion  of Tenant  Improvements  in the  Premises,  the date of  Substantial
Completion  thereof shall be deemed to be the date that  Substantial  Completion
would have  occurred  if no Tenant  Delay or  Delays,  as set forth  above,  had
occurred.

5.3 Delay of the  Substantial  Completion  of the  Premises  caused by Landlord.
Except as provided in this Section 5, the Additional  Premises Rent Commencement
Date and Tenant's  obligation  to pay rent for the  Premises  shall occur as set
forth in the Lease.  However,  if there  shall be a delay or there are delays in
the Substantial  Completion of the Tenant  Improvements in the Premises actually
and to the extent caused as a result of the following  (collectively,  "Landlord
Delays"):

                  5.3.1 Landlord's failure to comply with the Time Deadlines;

                  5.3.2 A breach by  Landlord  of the terms of this  Tenant Work
Letter or the Lease;

                  5.3.3 Any grossly negligent acts or omissions of Landlord,  or
its agents or employees;

then  notwithstanding  anything to the  contrary  set forth in the Lease or this
Tenant Work Letter and regardless of the actual date of the Substantial


                                      C-5
<PAGE>

Completion of Tenant Improvements in Premises,  (i) the Additional Premises Rent
Commencement  Date and (ii) the  Expiration  Date of the  initial  Term shall be
delayed  by the  number of days  equal to the  difference  between  the later of
October 1, 2005 or actual date of  Substantial  Completion and the date on which
Substantial  Completion  would have  occurred had there been no Landlord  Delays
(the "Landlord Delay Period"). In the event that the Tenant Improvements are not
completed by January 1, 2006, as a result of Landlord  Delays  exceeding 90 days
in the  aggregate,  then  Tenant  shall have the right to  terminate  the Fourth
Amendment  to Lease  upon  notice to  Landlord  within  ten (10)  business  days
thereafter and, in the event Tenant timely  exercises its termination  right, as
aforesaid,  the Fourth  Amendment  shall become null and void and the rights and
obligations of Landlord and Tenant shall  thereafter be governed  exclusively by
the  Original  Lease (as  defined  in the Fourth  Amendment  to Lease) as if the
Fourth Amendment had never existed including, without limitation, the payment of
Rent.  In  furtherance  of the  foregoing,  in the event  Tenant  exercises  its
termination  right,  Tenant  agrees to remit to Landlord all payments that would
have been due  pursuant to the  Original  Lease but were not paid as a result of
Tenant's entering into the Fourth Amendment.

                                    SECTION 6

                                  MISCELLANEOUS

6.1  Tenant's  Representative.  Tenant has  designated  Eric  Krause as its sole
representative with respect to the matters set forth in this Tenant Work Letter,
who,  until  further   notice  to  Landlord,   shall  have  full  authority  and
responsibility  to act on behalf of the Tenant as  required  in this Tenant Work
Letter.

6.2 Landlord's  Representative.  Prior to  commencement  of  construction of the
Tenant  Improvements,  Landlord shall designate a representative with respect to
the matters set forth in this Tenant Work Letter,  who,  until further notice to
Tenant,  shall have full  authority and  responsibility  to act on behalf of the
Landlord as required in this Tenant Work Letter.

6.3 Time of the Essence in This Tenant Work Letter.  Unless otherwise indicated,
all  references  herein to a "number of days"  shall mean and refer to  calendar
days.

6.4 Conditions to the  Disbursement of the  Construction  Allowance.  So long as
this  lease is in full force and  affect  and an Event of  Default  pursuant  to
Section 2.1 does not exist, landlord will disburse the Construction Allowance in
accordance with the following:

      (i)   up to a maximum  of four  hundred  thousand  dollars  ($400,000)  in
            accordance with section 2.2 of this tenant's work letter, and

      (ii)  the balance of fifty thousand dollars ($50,000) in five annual equal
            installments of ten thousand dollars ($10,000) each, due and payable
            within 15 business days after the 12th,  24th,  36th,  48th and 60th
            lease month after the Additional Premises Rent Commencement Date.


                                      C-6
<PAGE>

                                   SCHEDULE 1

                                 TIME DEADLINES

Dates                         Actions to be Performed
-----                         -----------------------

A.    July 22, 2005           Tenant to deliver Final Space Plan for the third
                              (3rd) floor to Landlord.

B.    Completed               Tenant to deliver Final Space Plan for the fifth
                              (5th) floor to Landlord.

C.    August 1, 2005          Tenant to deliver Final Working Drawings for the
                              third (3rd) floor to Landlord.

D.    Completed               Tenant to deliver Final Working Drawings for the
                              fifth (5th) floor to Landlord.

E.    Three (3) business days Landlord to approve Cost Proposal and return after
      the receipt of the Cost Proposal to Tenant. Cost Proposal by Landlord.


                                      C-7
<PAGE>

                                    EXHIBIT D

                                GUARANTY OF LEASE

      As  consideration   for  the  agreement  of  BROOKHAVEN   (NAUSHUA),   LLC
("Landlord")  to enter into that  certain  lease dated as of August 4, 1996,  as
amended as more  particularly  set forth in a certain Fourth  Amendment to Lease
dated as of July 11, 2005  (collectively,  the  "Lease")  between  Landlord  and
Critical Care Systems, Inc. ("Tenant), the undersigned ("Guarantor") does hereby
covenant and agree as follows:

A. The  undersigned  does hereby  absolutely,  unconditionally  and  irrevocably
guarantee the full, faithful and timely payment and performance by Tenant of all
of the payments,  covenants and other obligations of Tenant under or pursuant to
the Lease. If Tenant shall default at any time in the payment of any rent or any
other sums,  costs or charges  whatsoever,  or in the  performance of any of the
other covenants and obligations of Tenant,  under or pursuant to the Lease, then
the  undersigned,  at its expense,  shall on demand of said  Landlord  fully and
promptly,  and well and truly,  pay all rent, sums, costs and charges to be paid
by Tenant,  and perform all the other  covenants and obligations to be performed
by Tenant,  under or pursuant to the Lease,  and in addition shall on Landlord's
demand pay to  Landlord  any and all sums due to  Landlord,  including  (without
limitation)  all interest on past due  obligations of Tenant,  costs advanced by
Landlord, and damages and all expenses (including attorneys' fees and litigation
costs),  that may arise in  consequence  of Tenant's  default.  The  undersigned
hereby waives all  requirements of notice of the acceptance of this Guaranty and
all requirements of notice of breach or non-performance by Tenant.

B. The  obligations of the  undersigned  hereunder are  independent  of, and may
exceed,  the  obligations  of Tenant.  A  separate  action or  actions  may,  at
Landlord's option, be brought and prosecuted against the undersigned, whether or
not any action is first or subsequently  brought  against Tenant,  or whether or
not Tenant is joined in any such action,  and the  undersigned  may be joined in
any action or proceeding commenced by Landlord against Tenant arising out of, in
connection  with or based upon the Lease.  The  undersigned  waives any right to
require  Landlord  to  proceed  against  Tenant  to pursue  any other  remedy in
Landlord's power  whatsoever,  any right to complain of delay in the enforcement
of Landlord's  rights under the Lease,  and any demand by Landlord  and/or prior
action by Landlord of any nature whatsoever against Tenant, or otherwise.

C. This  Guaranty  shall  remain and continue in full force and effect and shall
not be  discharged  in  whole  or in  part  notwithstanding  (whether  prior  or
subsequent  to  the  execution  hereof)  any  alteration,   renewal,  extension,
modification,   amendment  or   assignment   of,  or   subletting,   concession,
franchising,  licensing  or  permitting  under the Lease.  Without  limiting the
foregoing,  this  Guaranty  shall be  applicable  to any  obligations  of Tenant
arising in connection with a termination of the Lease, whether voluntary or


                                      D-1
<PAGE>

otherwise.  The undersigned  hereby waives notices of any of the foregoing,  and
agrees that the liability of the  undersigned  hereunder shall be based upon the
obligations  of  Tenant  set  forth in the  Lease  as the  same may be  altered,
renewed,  extended,  modified,  amended  or  assigned.  For the  purpose of this
Guaranty and the  obligations  and  liabilities  of the  undersigned  hereunder,
"Tenant"  shall be deemed to  include  any and all  concessionaires,  licensees,
franchisees,  department operators, assignees, subtenants,  permittees or others
directly  or  indirectly  operating  or  conducting  a  business  in or from the
Premises, as fully as if any of the same were the named Tenant under the Lease.

D. The undersigned's  obligations  hereunder shall remain fully binding although
Landlord  may have waived one or more  defaults by Tenant,  extended the time of
performance by Tenant, released,  returned or misapplied under collateral at any
time given as security for Tenant's  obligations  (including  other  guaranties)
and/or released  Tenant from the performance of its obligations  under the Lease
or terminated the Lease.

E. This  Guaranty  shall  remain in full  force and effect  notwithstanding  the
institution by or against Tenant, of bankruptcy,  reorganization,  readjustment,
receivership or insolvency  proceedings of any nature,  or the  disaffirmance of
the Lease in any such proceedings or otherwise.

F. If this  Guaranty  is  signed  by more  than one  party,  or if more than one
Guaranty shall be given as security for the performance of Tenant's  obligations
under the Lease,  then the obligations of such parties and any other  guarantors
shall be joint and several,  and the release of one of such guarantors shall not
release any other of such guarantors.

G. This Guaranty  shall be applicable to and binding upon the heirs,  executors,
administrators,  representatives, successors and assigns of Landlord, Tenant and
the undersigned.  Landlord may, without notice, assign this Guaranty in whole or
in part.

H. In the event that Landlord should  institute any suit against the undersigned
for  violation  of or to enforce  any of the  covenants  or  conditions  of this
Guaranty  or  to  enforce  any  right  of  Landlord  hereunder,  or  should  the
undersigned  institute any suit against Landlord arising out of or in connection
with this  Guaranty,  or should either party  institute a suit against the other
for a declaration of rights  hereunder,  or should either party intervene in any
suit in which the other is a party to enforce or protect the intervening party's
interest or rights  hereunder,  Landlord shall receive from the  undersigned all
costs and  expenses  paid or  incurred  by  Landlord  in  connection  therewith,
including, without limitation, the fees of its attorney(s).

I. THE  UNDERSIGNED  HEREBY  WAIVES TRIAL BY JURY IN ANY ACTION,  PROCEEDING  OR
COUNTERCLAIM  BROUGHT  BY ANY  PERSON  OR  ENTITY  WITH  RESPECT  TO ANY  MATTER
WHATSOEVER  ARISING OUT OF OR IN ANY WAY  CONNECTED  WITH:  THIS  GUARANTY,  THE
LEASE; ANY LIABILITY OR


                                      D-2
<PAGE>

OBLIGATION OF TENANT IN ANY MANNER RELATED TO THE PREMISES;  ANY CLAIM OF INJURY
OR  DAMAGE  IN ANY WAY  RELATED  TO THE  LEASE OR THE  PREMISES;  ANY  ACTION OR
OMISSION OF TENANT, ITS AGENTS,  EMPLOYEES,  CONTRACTORS,  SUPPLIERS,  SERVANTS,
CUSTOMERS OR LICENSEES; OR ANY ASPECT OF THE USE OR OCCUPANCY OF, OR THE CONDUCT
OF BUSINESS IN, ON OR FROM THE PREMISES.  The  undersigned  shall not impose any
counterclaim or counterclaims or claims for set-off,  recoupment or deduction of
rent in any action  brought  by  Landlord  against  the  undersigned  under this
Guaranty.  The undersigned hereby waives both with respect to the Lease and with
respect to this  Guaranty,  any and all rights  which are waived by Tenant under
the Lease, in the same manner as if all such waivers were fully restated herein.
The   liability  of  the   undersigned   under  this  Guaranty  is  primary  and
unconditional.

J. The undersigned shall not be subrogated, and hereby waives any and all rights
of  subrogation  (if any),  to any of the rights of Landlord  under the Lease or
otherwise, or to or in the Premises thereunder, which may arise by reason of any
of the  provisions  of this  Guaranty  or by  reason of the  performance  by the
undersigned of any of its  obligations  hereunder.  The  undersigned  shall look
solely to Tenant for any  recoupment  of any payments  made or costs or expenses
incurred by the undersigned pursuant to this Guaranty.

K. Any default or failure by the  undersigned to perform any of its  obligations
under this Guaranty  shall be deemed to be an immediate  default by Tenant under
the Lease.

L. The  execution  of this  Guaranty  prior to  execution of the Lease shall not
invalidate this Guaranty or lessen the obligations of Guarantor(s) hereunder.

M. This  Guaranty  shall be governed  by the laws of the State of New  Hampshire
(without giving effect to its rules governing conflicts of laws).

N. All notices or other  communications to be provided pursuant to this Guaranty
shall be in  writing  and  shall be  deemed  to be  properly  served  if sent by
registered or certified mail or Federal  Express or similar courier service with
overnight delivery or via professional messenger service (with receipt therefor)
or by certified or registered mail, return receipt requested.

      IN WITNESS WHEREOF,  the undersigned has executed this Guaranty as of July
11, 2005.


WITNESS:                                    GUARANTOR:

                                            CURATIVE HEALTH SERVICES, INC.
                                            A Minnesota corporation

By:   /s/ Robin J. Flynn                    By:   /s/ John C. Prior
      ---------------------------                 ------------------------------
Name: Robin J. Flynn                        Name: John C. Prior
      ---------------------------                 ------------------------------
                                            Title:     C.O.O.
                                                  ------------------------------

                                      D-3