ASSIGNMENT AND SECURITY AGREEMENT

     THIS  ASSIGNMENT  AND SECURITY  AGREEMENT  (this  "Agreement")  is made and
entered  into as of the 1st day of April,  2000,  by and between  Prime  Medical
Services,  Inc., a Delaware  corporation  (the "Secured  Party") and Ken Moadel,
M.D. ("Moadel").

                                    RECITALS:

         A. Moadel and Secured Party have  executed and  delivered  that certain
Contribution  Agreement dated effective April 1, 2000, between and among Moadel,
Ken Moadel, M.D., P.C., a New York professional corporation,  Secured Party, New
York  Laser  Management,  L.L.C.,  a Delaware  limited  liability  company  (the
"Debtor")  and  Prime  RVC,   Inc.,  a  Delaware   corporation   ("Prime")  (the
"Contribution  Agreement"),  and Debtor and  Secured  Party  have  executed  and
delivered  that  certain  Loan  Agreement,   dated  April  1,  2000  (the  "Loan
Agreement"),  pursuant to which  Secured  Party agrees to make certain  loans to
Debtor on the terms and subject to the conditions provided therein.

         B. Secured Party has requested  that Moadel pledge the  Collateral  (as
defined below) to secure certain obligations and liabilities that Debtor may now
or  hereafter  have  to  Secured  Party,  including,   without  limitation,  any
obligations arising under loans made pursuant to the Loan Agreement.

     C. Moadel desires to enter into this Agreement as a material  inducement to
Secured Party's extension of credit under the Loan Agreement.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which Moadel  acknowledges,  Moadel and Secured Party
agree as follows:

                                    ARTICLE I

                       COLLATERAL AND SECURED OBLIGATIONS

         1.1 Grant of Security Interest.  Moadel hereby assigns,  transfers, and
pledges to Secured  Party,  and Moadel hereby grants to Secured Party a security
interest   in,   the   following   described   collateral   (collectively,   the
"Collateral"):

     (a) Interest in  Subsidiary.  All ownership  interests of Moadel in Debtor,
whether now existing or hereafter  acquired and including,  without  limitation,
that certain thirty-five percent (35%) membership interest in Debtor;

                  (b)  Accounts.  All  accounts  and  rights  now  or  hereafter
attributable to any of the Collateral  described in (a) above, and all rights of
Moadel now or hereafter arising under any agreement pertaining to the Collateral
described  in  (a)  above,   including  without  limitation  all  distributions,
proceeds, fees, dividends,  preferences,  payments or other benefits of whatever
nature  which  Moadel is now or may  hereafter  become  entitled to receive with
respect to any Collateral described in (a) above;

                  (c) Additional  Property.  "Collateral" shall also include the
following  property  (collectively,  the  "Additional  Property")  which  Moadel
becomes entitled to receive or shall receive as a result of its ownership of any
other  Collateral:  (i) any  stock or  other  ownership  certificate,  including
without  limitation,  any  certificate  representing  a  stock  dividend  or any
certificate in connection with any recapitalization,  reclassification,  merger,
consolidation,  conversion,  sale of assets,  combination,  stock split, reverse
stock  split,  or spin-off;  (ii) any option,  warrant,  subscription  or right,
whether as an addition to or in substitution of any other Collateral;  (iii) any
dividends or  distributions  of any kind  whatsoever,  whether  distributable in
cash, stock or other property; (iv) any interest, premium or principal payments;
and (v) any conversion or redemption proceeds; and

                  (d) Proceeds.  All proceeds (cash and non-cash) arising out of
the sale, exchange, collection or other disposition of all or any portion of the
Collateral  described in (a),  (b) or (c) above,  including  without  limitation
proceeds in the form of stock, accounts, chattel paper, instruments,  documents,
goods, inventory and equipment.

The  security  interest in the  Collateral  hereby  granted by Moadel to Secured
Party may sometimes be referred to in this Agreement as the "Security Interest".

         1.2 Obligations.  This Agreement and the Security Interest shall secure
full and punctual payment and performance of the following indebtedness,  duties
and obligations (collectively, the "Obligations"):

                  (a) All liabilities and obligations of Debtor to Secured Party
(including, without limitation, any principal, interest, fees and other amounts,
and any other  obligations)  under and pursuant to the Loan  Agreement  and each
promissory  note  (collectively,   the  "Note")  issued  pursuant  to  the  Loan
Agreement; and

                  (b) All  liabilities  and  obligations  of Debtor  to  Secured
Party,  Prime, or any Prime  Indemnified  Party (as defined in the  Contribution
Agreement) under and pursuant to the Contribution Agreement or this Agreement.

                                   ARTICLE II

       MOADEL'S REPRESENTATIONS AND WARRANTIES WITH RESPECT TO COLLATERAL

         Moadel hereby represents and warrants to Secured Party as follows:

         2.1 Ownership of Collateral.  Moadel has good and  marketable  title to
the Collateral  free and clear of any liens,  security  interests,  shareholders
agreement, calls, charge, or encumbrance,  except for this Security Interest. No
financing  statement or other  instrument  similar in effect covering all or any
part of the  Collateral is on file in any recording  office,  except as may have
been filed in favor of Secured Party relating to this Agreement.

         2.2  Power  &  Authority.  Moadel  has the  lawful  right,  power,  and
authority  to grant the Security  Interest in the  Collateral.  This  Agreement,
together  with all filings and other  actions  necessary or desirable to perfect
and protect such security interest,  which have been duly taken,  create a valid
and perfected first priority  security  interest in the Collateral  securing the
payment and performance of the Obligations.

         2.3 No  Agreements.  The  Interests  are not  subject  to any  right of
redemption,  or any  call or put  options,  voting  trust,  proxy,  shareholders
agreement,  right of first  refusal,  or any other  document or agreement  which
would in any way impair or adversely affect this Security Interest or the rights
of Secured Party under this Agreement.

         2.4  Securities.  Any  certificates  evidencing  securities  pledged as
Collateral  are valid and  genuine  and have not been  altered.  All  securities
pledged as Collateral have been duly  authorized and validly  issued,  are fully
paid and  non-assessable,  and were not issued in  violation  of the  preemptive
rights of any party or of any agreement by which Moadel or the issuer thereof is
bound.  Except as expressly provided otherwise in the Contribution  Agreement or
any  Transaction  Document (as therein  defined),  no restrictions or conditions
exist  with  respect  to the  transfer  or voting of any  securities  pledged as
Collateral.

                                   ARTICLE III

                  MOADEL'S OTHER REPRESENTATIONS AND WARRANTIES

         3.1 Solvency of Moadel.  As of the date hereof,  (i) Moadel is solvent;
(ii) the fair saleable value of Moadel's  assets exceeds its  liabilities  (both
fixed and  contingent);  (iii) Moadel has  sufficient  capital to satisfy all of
Moadel's obligations as they become due; (iv) no receiver, trustee, or custodian
has been appointed for, or taken possession of, all or substantially  all of the
assets of Moadel,  either in a  proceeding  brought by Moadel or in a proceeding
brought against  Moadel;  (v) Moadel is not the subject of a petition for relief
under  the  United  States  Bankruptcy  Code or any  similar  federal  or  state
insolvency  law,  including  without  limitation a petition filed by Moadel or a
petition filed by a third party seeking relief against  Moadel;  and (vi) Moadel
has no  intention  of filing a  petition  for  relief  under the  United  States
Bankruptcy  Code or any similar  federal or state  insolvency law, or of seeking
any other form of creditor relief.

         3.2  Authority and  Compliance.  Moadel has full power and authority to
enter into this Agreement. Moadel has full power and authority to enter into and
perform  its  obligations  under each  Other  Agreement.  No further  consent or
approval is required as a condition  to the  validity of this  Agreement  or any
Other Agreement.  Moadel is in compliance with all applicable laws,  ordinances,
statutes, orders, regulations,  judgments, writs, or decrees of any governmental
entity to which it is subject.

         3.3  Binding  Agreement.   This  Agreement  and  each  Other  Agreement
constitute valid and legally binding  obligations of Moadel,  in accordance with
their terms, subject to the applicable bankruptcy,  insolvency,  reorganization,
moratorium, and similar laws affecting creditors' rights generally.

         3.4 Litigation.  There are no proceedings  pending or, to the knowledge
of Moadel,  threatened before any court or  administrative  agency which will or
may have a material adverse effect on the financial  condition of Moadel or upon
Moadel's  ability to perform its  obligations  under this Agreement or any Other
Agreement.

         3.5 No Conflicting Agreements.  There are no provisions of any existing
agreement,  mortgage,  indenture or contract  binding on Moadel or affecting its
property,  which  would  conflict  with or in any  way  prevent  the  execution,
delivery, or carrying out of the terms of this Agreement or any Other Agreement.

         3.6  Ownership  of  Assets.  Moadel  has  good  and  full  title to the
Collateral,  and the  Collateral  is owned  free and  clear of  liens,  charges,
claims, security interests, and other encumbrances.

     3.7 Taxes. Moadel has filed all tax returns required to be filed by Moadel.

                                   ARTICLE IV

                  MOADEL'S COVENANTS WITH RESPECT TO COLLATERAL

         Moadel  covenants  and agrees  that from the date  hereof and until the
payment  and  performance  in  full  of the  Obligations  unless  Secured  Party
otherwise consents in writing:

         4.1  Delivery of  Instruments  and/or  Certificates.  Contemporaneously
herewith,   Moadel  covenants  and  agrees  to  deliver  to  Secured  Party  any
certificates,   documents,   or  instruments   representing  or  evidencing  the
Collateral,  with Moadel's  endorsement  thereon  and/or  accompanied  by proper
instruments of transfer and assignment duly executed in blank.

         4.2  Further  Assurances.   Moadel  will   contemporaneously  with  the
execution  hereof  and from  time to time  thereafter  at its  expense  promptly
execute and deliver all further  instruments  and documents and take all further
action  necessary or  appropriate or that Secured Party may request in order (i)
to perfect and protect the security  interest created or purported to be created
hereby and the first priority of such security interest,  (ii) to enable Secured
Party to exercise  and enforce its rights and  remedies  hereunder in respect of
the  Collateral,  and (iii) to otherwise  effect the purposes of this Agreement,
including  without  limitation:  (A)  executing  and  filing  any  financing  or
continuation  statements,  or any  amendments  thereto;  (B)  obtaining  written
confirmation  from the issuer of any  securities  pledged as  Collateral  of the
pledge of such securities,  in form and substance satisfactory to Secured Party;
(C)  cooperating  with Secured Party in registering the pledge of any securities
pledged as Collateral with the issuer of such securities;  (D) delivering notice
of Secured Party's security interest in any securities  pledged as Collateral to
any securities or financial  intermediary,  clearing  corporation or other party
required by Secured Party, in form and substance  satisfactory to Secured Party;
and  (E)  obtaining  written  confirmation  of  the  pledge  of  any  securities
constituting Collateral from any securities or financial intermediary,  clearing
corporation  or other party  required by Secured  Party,  in form and  substance
satisfactory to Secured Party.

         4.3 Additional Property. All Additional Property, as defined in Section
1.1(c)  above,  received by Moadel shall be received in trust for the benefit of
Secured Party.  All Additional  Property and all  certificates  or other written
instruments or documents  evidencing and/or representing the Additional Property
that is  received  by Moadel,  together  with such  instruments  of  transfer as
Secured Party may request,  shall  immediately be delivered to or deposited with
Secured Party and held by Secured  Party as  Collateral  under the terms of this
Agreement.  If the  Additional  Property  received  by Moadel and  delivered  to
Secured  Party  pursuant  to this  Section  shall  be  shares  of stock or other
securities,  such shares of stock or other  securities shall be duly endorsed in
blank or  accompanied  by proper  instruments  of transfer and  assignment  duly
executed in blank with, if requested by Secured Party,  signatures guaranteed by
a member or member  organization  in good standing of an  authorized  Securities
Transfer Agents  Medallion  Program,  all in form and substance  satisfactory to
Secured  Party.  Secured  Party  shall  be  deemed  to  have  possession  of any
Collateral in transit to Secured Party or its agent.

         4.4  Sale,  Transfer,  Encumbrance.  Moadel  will not  sell,  transfer,
mortgage,  or otherwise  encumber any  Collateral or impair the value thereof in
any manner without  Secured  Party's prior written  consent,  including  without
limitation by purchase, lease, barter, trade, payment deferral, or the creation,
assumption  or guarantee of  indebtedness  or other  lending of credit.  Secured
Party's written consent to any sale,  mortgage,  transfer,  or encumbrance shall
not be construed to be a waiver of this  provision in respect to any  subsequent
proposed sale, mortgage, transfer, or encumbrance.

         4.5 Liens. Neither Moadel nor any person acting on Moadel's behalf has,
or shall have any right, power, or authority to and shall not create,  incur, or
permit to be placed or  imposed,  upon the  Collateral,  any lien of any type or
nature whatsoever, other than the liens in favor of Secured Party.

         4.6 Matters or  Occurrences  Affecting  Collateral  or this  Agreement.
Moadel will promptly  notify Secured Party of any and all matters or occurrences
that may have a material adverse effect on the status or value of the Collateral
or this Agreement,  including  without  limitation the occurrence of an Event of
Default,  or an event  which,  with giving of notice or lapse of time,  or both,
would constitute an Event of Default.

     4.7  Agreements  Pertaining  to  Collateral.  Moadel will not  transfer any
voting rights pertaining to the Collateral to any person or entity.

         4.8 Dilution of Ownership.  As to any securities pledged as Collateral,
Moadel  will not  consent to or approve of the  issuance  of (i) any  additional
interests  or  shares  of any  class  of  securities  of such  issuer,  (ii) any
instrument  convertible  voluntarily by the holder thereof or automatically upon
the occurrence or non-occurrence of any event or condition into, or exchangeable
for, any such  securities,  or (iii) any warrants,  options,  contracts or other
commitments  entitling any third party to purchase or otherwise acquire any such
securities.

         4.9  Restrictions  on  Securities.  Moadel  will  not  enter  into  any
agreement  creating,  or otherwise permit to exist, any restriction or condition
upon the transfer,  voting or control of any  securities  pledged as Collateral,
except as consented to in writing by Secured Party. As to any securities pledged
as collateral, Moadel will not consent to or approve of any stock split, reverse
stock  split,  stock  dividend,  reclassification,   or  other  similar  act  or
transaction  regarding the Interests  unless  consented to in writing by Secured
Party.

                                    ARTICLE V

                         MOADEL'S AFFIRMATIVE COVENANTS

         Until payment and performance of all Obligations,  Moadel covenants and
agrees that it shall promptly  advise Secured Party in writing of any litigation
filed  against  Moadel  and of any  condition,  event or act which  comes to its
attention  that  would or might  have a  material  adverse  effect  on  Moadel's
financial condition.

                                   ARTICLE VI

                               NEGATIVE COVENANTS

         Until payment and performance of all Obligations,  Moadel covenants and
agrees that Moadel will not,  without the prior written consent of Secured Party
grant, suffer, or permit liens on, or security interests in, the Collateral.

                                   ARTICLE VII

                              DEFAULT AND REMEDIES

     7.1 Events of Default.  An Event of Default  (herein so called) shall exist
if any one or more of the following events shall occur:

                  (a) The  failure  of Debtor to pay any amount  required  to be
paid  under  the Loan  Agreement  or any Note  (including,  without  limitation,
principal, interest and fees due thereunder) within ten (10) calendar days after
such amount is due;

                  (b) The failure of Debtor to pay any  Obligation  described in
Section  1.2(b)  within ten (10) calendar days after such amount is due (and, if
applicable  under the terms of any contractual  agreement  creating or governing
such Obligation, after the expiration of any cure period expressly required);

                  (c)      Moadel's breach of a covenant in this Agreement;

     (d) Any  representation  or warranty made by Moadel in this Agreement shall
be false or materially misleading, as determined in the reasonable discretion of
Secured Party;

                  (e) Any event of default  shall  occur  under the terms of the
Loan  Agreement  and shall not be cured within the time  expressly  provided for
with respect thereto in the Loan Agreement;

                  (f) If Debtor, or any other party obligated to pay any portion
of the  Obligations:  (i)  becomes  insolvent,  or makes a transfer  in fraud of
creditors,  or makes an assignment  for the benefit of  creditors,  or admits in
writing its inability to pay its debts as they become due; (ii) generally is not
paying its debts as such debts  become due and  Secured  Party,  in good  faith,
determines that such event or condition  could lead to a material  impairment of
the Collateral, or any part thereof, or of any other payment security for any of
the Obligations;  (iii) has a receiver,  trustee or custodian  appointed for, or
take possession of, all or substantially  all of the assets of such party or any
of the  Collateral,  either  in a  proceeding  brought  by  such  party  or in a
proceeding  brought against such party and such appointment is not discharged or
such  possession  is not  terminated  within sixty (60) days after the effective
date thereof or such party  consents to or  acquiesces  in such  appointment  or
possession;  (iv) files a petition for relief under the United States Bankruptcy
Code or any other present or future federal or state  insolvency,  bankruptcy or
similar laws (all of the foregoing  hereinafter  collectively called "Applicable
Bankruptcy  Law") or an  involuntary  petition for relief is filed  against such
party under any Applicable  Bankruptcy Law and such involuntary  petition is not
dismissed  within  sixty  (60) days after the  filing  thereof,  or an order for
relief naming such party is entered under any Applicable  Bankruptcy Law, or any
composition, rearrangement, extension, reorganization or other relief of debtors
now or hereafter  existing is requested or consented to by such party; (v) fails
to  have  discharged  within  a  period  of  sixty  (60)  days  any  attachment,
sequestration  or similar writ levied upon,  or any claim  against or affecting,
any  property  of such party;  or (vi) fails to pay within  ninety (90) days any
final money judgment against such party; or

                  (g) The issuer of any securities constituting Collateral files
a petition  for relief  under any  Applicable  Bankruptcy  Law,  an  involuntary
petition  for  relief is filed  against  any such  issuer  under any  Applicable
Bankruptcy Law and such involuntary petition is not dismissed within thirty (30)
days after the filing thereof,  or an order for relief naming any such issuer is
entered under any Applicable Bankruptcy Law.

     7.2 Secured Party's Remedies. Upon the occurrence of an Event of Default:

                  (a) Secured Party may declare the Obligations in whole or part
immediately due and may enforce payment and performance of the same and exercise
any rights under the Texas UCC,  rights and remedies of Secured Party under this
Agreement, or otherwise.

                  (b) Secured  Party may, at Secured  Party's  option and at the
expense of Moadel,  either in Secured Party's own right or in the name of Moadel
and in the same manner and to the same extent that Moadel  might  reasonably  so
act  if  this  Agreement  had  not  been  made:  (i) do  all  things  requisite,
convenient,  or  necessary  to enforce the  performance  and  observance  of all
rights,  remedies and privileges of Moadel arising from the  Collateral,  or any
part thereof,  including without limitation compromising,  waiving, excusing, or
in any manner releasing or discharging any obligation of any party to or arising
from the Collateral;  (ii) take possession of the books, papers,  chattel paper,
documents of title, and accounts of Moadel,  wherever  located,  relating to the
Collateral; (iii) sue or otherwise collect and receive money attributable to the
Collateral;  and (iv) exercise any other lawfully  available powers or remedies,
and do all other things  which  Secured  Party deems  requisite,  convenient  or
necessary  or which the  Secured  Party  deems  proper to protect  the  Security
Interest.

                  (b) Secured Party may foreclose  this  Agreement in the manner
now or  hereafter  provided  or  permitted  by law and may upon such  reasonable
notification  prior thereto as may be required by applicable  law (Moadel hereby
agreeing  that ten  days'  notice is  commercially  reasonable),  sell,  assign,
transfer,  or otherwise  dispose of the Collateral at public or private sale, in
whole  or in  part,  and  Secured  Party  may,  in its own  name or as  Moadel's
attorney-in-fact  effectively  assign and transfer the  Collateral,  or any part
thereof,   absolutely,  and  execute  and  deliver  all  necessary  assignments,
conveyances,  bills of sale, and other  instruments with power to substitute one
or more persons or  corporations  with like power.  Any such  foreclosure  sale,
assignment,  transfer,  or other  disposition  shall, to the extent permitted by
law,  be a  perpetual  bar,  both at law and in equity,  against  Moadel and all
persons and corporations  lawfully  claiming by or through or under Moadel.  Any
such foreclosure sale may be adjourned from time to time. Upon any sale, Secured
Party may bid for and purchase the  Collateral,  or any part  thereof,  and upon
compliance with the terms of sale may hold,  retain,  possess and dispose of the
Collateral, in its absolute right without further accountability.  Secured Party
shall have the right to be  credited  on the  amount of its bid a  corresponding
amount of the Obligations as of the date of such sale.

                  (c) If, in the opinion of Secured Party, there is any question
that a public sale or  distribution  of any Collateral will violate any state or
federal  securities  law,  Secured  Party  (i) may  offer  and  sell  securities
privately to purchasers who will agree to take them for investment  purposes and
not with a view to distribution  and who will agree to imposition of restrictive
legends on the  certificates  representing  the security,  or (ii) may sell such
securities in any type of offering  which  complies  with, or is exempt from the
registration requirements of, the Securities Act of 1933, and no sale so made in
good faith by Secured Party shall be deemed to be not "commercially  reasonable"
because so made.

                  (d)  Not  in  limitation  of  any  other   provision  of  this
Agreement,  Secured  Party shall have all rights and remedies of a secured party
under the Texas UCC.

         7.3  Application  of Proceeds.  Secured Party may apply the proceeds of
any foreclosure  sale hereunder or from any other  permitted  disposition of the
Collateral  or any part  thereof as  follows:  (a) first,  to the payment of all
reasonable  costs and expenses of any foreclosure  and collection  hereunder and
all proceedings in connection  therewith,  including reasonable attorneys' fees;
(b) then, to the  reimbursement of Secured Party for all  disbursements  made by
Secured Party for taxes,  assessments or liens superior to the Security Interest
and  which  Secured  Party  shall  deem  expedient  to  pay;  (c)  then,  to the
reimbursement of Secured Party of any other  disbursements made by Secured Party
in accordance  with the terms hereof or under the  Contribution  Agreement,  the
Loan Agreement or any Note; (d) then, to or among the amounts of fees,  interest
and  principal  then owing and unpaid in  respect  of the  Obligations,  in such
priority as Secured Party may determine in its discretion; and (e) the remainder
of such  proceeds,  if any,  shall be paid to Moadel.  If such proceeds shall be
insufficient to discharge the entire  Obligations,  Secured Party shall have any
other available legal recourse  against Moadel under, or for the performance of,
the Contribution Agreement, the Loan Agreement and any Note, for the deficiency,
together with interest  thereon at the maximum rate permitted  under  applicable
law.

         7.4  Enforcement  of  Obligations.  Nothing in this Agreement or in any
other  document  or  agreement  shall  affect or impair  the  unconditional  and
absolute right of Secured Party to enforce the  Obligations as and when the same
shall become due.

                                  ARTICLE VIII

                             RIGHTS OF SECURED PARTY

         8.1  Subrogation.  Upon the occurrence of an Event of Default,  Secured
Party,  at its  election,  may  subrogate  to all of the  interest,  rights  and
remedies of Moadel, in respect to any of the Collateral or agreements pertaining
thereto.

         8.2 Secured Party  Appointed  Attorney-in-Fact.  Moadel hereby appoints
Secured Party as  attorney-in-fact  of Moadel,  with full authority in the place
and stead of Moadel and in the name of Moadel, Secured Party or otherwise,  from
time to time on Secured  Party's  discretion and upon the occurrence of an Event
of Default, to take any action and to execute any instrument which Secured Party
may deem  necessary or advisable to accomplish  the purposes of this  Agreement,
including without  limitation:  (a) to ask, demand,  collect,  sue for, recover,
compound, receive and give acquittance and receipts for moneys due and to become
due under or in respect of any of the Collateral;  (b) to receive,  endorse, and
collect  any  drafts or other  instruments,  documents  and  chattel  paper,  in
connection  with clause (a) of this  Section 8.2; (c) to file any claims or take
any action or institute any proceeding which Secured Party may deem necessary or
desirable for the  collection  of any of the  Collateral or otherwise to enforce
the rights of Secured Party against any of the Collateral; and (d) to assign and
transfer the  Collateral,  or any part  thereof,  absolutely  and to execute and
deliver  endorsements,   assignments,  conveyances,  bills  of  sale  and  other
instruments  with power to substitute  one or more persons or  corporation  with
like power.

         8.3  Performance  by Secured  Party.  If Moadel  fails to  perform  any
agreement  contained  herein,  Secured  Party may itself  perform,  or cause the
performance  of, such  agreement,  and the reasonable  expenses of Secured Party
incurred in connection  therewith  shall be payable by Moadel under Section 8.8.
In no  event,  however,  shall  Secured  Party  have any  obligation  or  duties
whatsoever to perform any covenant or agreement of Moadel contained herein,  and
any such performance by Secured Party shall be wholly discretionary with Secured
Party.

         8.4 Duties of Secured  Party.  The powers  conferred upon Secured Party
hereunder  are solely to protect its  interest in the  Collateral  and shall not
impose any duty upon it to exercise any such powers. Except for the safe custody
of any  Collateral  in its  possession  and the  accounting  for money  actually
received by it hereunder,  Secured Party shall have no duty as to any Collateral
or as to the taking of any  necessary  steps to preserve  rights  against  prior
parties or any other rights pertaining to any Collateral.

         8.5 No  Liability  of Secured  Party.  Neither the  acceptance  of this
Agreement by Secured Party,  nor the exercise of any rights hereunder by Secured
Party,  shall be construed in any way as an  assumption  by Secured Party of any
obligations,  responsibilities,  or duties of Moadel arising in connection  with
the  Collateral  assigned  hereunder  or  otherwise  bind  Secured  Party to the
performance of any  obligations  respecting the  Collateral,  it being expressly
understood  that Secured  Party shall not be obligated to perform,  observe,  or
discharge  any  obligation,  responsibility,  duty,  or  liability  of Moadel in
respect of any of the Collateral,  including without limitation  appearing in or
defending any action, expending any money or incurring any expense in connection
therewith.  TO THE FULLEST EXTENT  PERMITTED BY APPLICABLE LAW, MOADEL SHALL AND
DOES AGREE TO INDEMNIFY, PROTECT, DEFEND AND HOLD HARMLESS SECURED PARTY AND ITS
SUBSIDIARIES,  AND EACH OF THEIR OFFICERS, DIRECTORS,  REPRESENTATIVES,  AGENTS,
EMPLOYEES,  LENDERS,  SUCCESSORS AND ASSIGNS,  FROM AND AGAINST ALL LIABILITIES,
CLAIMS, DAMAGES,  LOSSES, FINES, PENALTIES,  CAUSES OF ACTIONS, SUITS, JUDGMENTS
AND EXPENSES (INCLUDING COURT COSTS,  ATTORNEY'S FEES AND COST OF INVESTIGATION)
OF ANY  NATURE,  KIND OR  DESCRIPTION  OF ANY  PERSON  OR  ENTITY,  DIRECTLY  OR
INDIRECTLY,  ARISING OUT OF, CAUSED BY OR RESULTING  FROM (IN WHOLE OR IN PART),
ANY ACT OR  OMISSION  OF SECURED  PARTY,  OR ANYONE  ACTING ON BEHALF OF SECURED
PARTY,  IN CONNECTION  WITH THE  COLLATERAL,  INCLUDING  WITHOUT  LIMITATION ANY
MARKET FLUCTUATIONS IN THE COLLATERAL AS A RESULT OF SECURED PARTY'S SALE OF, OR
FAILURE TO SELL, THE INTERESTS AT ANY  PARTICULAR  TIME WHEN IT HAS THE RIGHT TO
DO  SO.  THE  FOREGOING  INDEMNITY  SHALL  SURVIVE  THE  EXPIRATION  OR  EARLIER
TERMINATION OF THIS AGREEMENT.

         8.6 Right of Secured Party to Defend Action Affecting Security. Secured
Party  may,  at the  expense  of  Moadel,  appear in and  defend  any  action or
proceeding at law or in equity  purporting to affect  Secured  Party's  Security
Interest under this Agreement.

         8.7 Right of  Secured  Party to Prevent  or Remedy  Default.  If Moadel
shall fail to perform any of the covenants,  conditions and agreements  required
to be performed and observed by Moadel under any Other Agreement,  or in respect
of the Collateral (subject to any applicable default cure period), Secured Party
(a) may but  shall not be  obligated  to take any  action  Secured  Party  deems
necessary  or  desirable  to  prevent  or remedy  any such  default by Moadel or
otherwise to protect the Security Interest,  and (b) shall have the absolute and
immediate right to take possession of the Collateral or any part thereof (to the
extent Secured Party has not previously taken  possession) to such extent and as
often as the Secured Party, in its sole discretion, deems necessary or desirable
in order to prevent  or to cure any such  default by  Moadel,  or  otherwise  to
protect the security of this Agreement. Secured Party may advance or expend such
sums of money for the account of Moadel as Secured Party in its sole  discretion
deems necessary for any such purpose.

         8.8 Secured Party's Expenses. All reasonable advances, costs, expenses,
charges and attorneys' fees which Secured Party may make, pay or incur under any
provision  of this  Agreement  for the  protection  of its  security  or for the
enforcement of any of its rights hereunder,  including,  without limitation,  in
foreclosure proceedings commenced and subsequently abandoned.

         8.9.  Remedies.  No right or remedy herein reserved to Secured Party is
intended to be exclusive  of any other right or remedy,  but each and every such
remedy shall be cumulative,  not in lieu of, but in addition to any other rights
or remedies given under this Agreement and all other security documents. Any and
all of Secured  Party's  rights and remedies may be exercised  from time to time
and as often as such exercise as deemed necessary or desirable by Secured Party.

         8.10 Moadel's Waivers.  Moadel waives notice of the creation,  advance,
increase,  existence,  extension,  or  renewal  of, and of any  indulgence  with
respect to, the  Obligations;  waives notice of intent to accelerate,  notice of
acceleration,  notice  of  intent  to  demand,  presentment,  demand,  notice of
dishonor,  and  protest;   waives  notice  of  the  amount  of  the  Obligations
outstanding  at any time,  notice of any change in  financial  condition  of any
person liable for the  Obligations  or any part thereof,  notice of any Event of
Default,  and all other  notices  respecting  the  Obligations;  and agrees that
maturity of the Obligations  and any part thereof may be accelerated,  extended,
or renewed one or more times by Secured Party in its discretion,  without notice
to Debtor.

         8.11 Other Parties and Other Collateral.  No renewal or extension of or
any other  indulgence  with respect to the  Obligations or any part thereof,  no
release  of any  security,  no  release  of any  person  (including  any  maker,
endorser,  guarantor,  or  surety)  liable  on  the  Obligations,  no  delay  in
enforcement  of payment,  and no delay or admission or lack of diligence or care
in exercising any right or power with respect to the Obligations or any security
therefor  or  guaranty  thereof or under this  Agreement  shall in other  manner
impair  or affect  the  rights  of  Secured  Party  under  the law,  under  this
Agreement,  or under any other  document or  agreement  pertaining  to the other
security for the  Obligations,  before  foreclosing  upon the Collateral for the
purpose of paying the Obligations.  Moadel waives any right to the benefit of or
to require or control application of any other security or proceeds thereof, and
Moadel  agrees that Secured  Party shall have no duty or obligation to Moadel to
apply to the Obligations any such other security or proceeds thereof.

                                   ARTICLE IX

                                  MISCELLANEOUS

     9.1 Terms  Commercially  Reasonable.  The terms of this Agreement  shall be
deemed commercially reasonable within the meaning of the Texas UCC.

         9.2 Notices.  Any notices or demands  required or permitted to be given
hereunder  shall be  deemed  sufficiently  given if in  writing  and  personally
delivered or mailed (with all postage and charges prepaid), addressed to Secured
Party or to Moadel their respective  addresses set forth below, or at such other
address as the above parties may from time to time  designate by written  notice
to the other given in  accordance  with this Section  9.2.  Any such notice,  if
personally  delivered or  transmitted  by telex or telegram,  shall be deemed to
have been given on the date so delivered or transmitted or, if mailed, be deemed
to have been given on the day after such  notice is placed in the United  States
mail in accordance with this Section 9.2.

                  Secured Party:       1301 Capital of Texas Hwy., Suite C-300
                                       Austin, Travis County, Texas 78746
                                       Attn: President

                  with copy to:        Timothy L. LaFrey, Esq.
                                       Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                       1900 Frost Bank Plaza
                                       816 Congress Avenue
                                       Austin, Texas 78701

                  Moadel:              Ken Moadel, M.D.
                                       16 East 53rd Street, 5th Floor
                                       New York, New York  10022


         9.3 Parties Bound.  Secured Party's rights under this Agreement and the
Security Interest shall inure to the benefits of its successors and assigns, and
in the event of any  assignment  or  transfer of any of the  Obligations  or the
Collateral,  Secured  Party  thereafter  shall  be  fully  discharged  from  any
responsibility  with respect to the Collateral so assigned or  transferred,  but
Secured  Party shall  retain all rights and powers  hereby given with respect to
any of the  Obligations  or  Collateral  not so  assigned  or  transferred.  All
representations, warranties, and agreements of Moadel if more than one are joint
and several, and all shall be binding upon the personal representatives,  heirs,
successors, and assigns of Moadel.

         9.4 Waiver.  No delay of Secured Party in exercising any power or right
shall operate as a waiver thereof;  nor shall any single or partial  exercise of
any power or right preclude other or further exercise thereof or the exercise of
any other power or right.  No waiver by Secured Party of any right  hereunder of
any default by Moadel shall be binding upon Secured Party unless in writing, and
no failure by Secured  Party to exercise any power or right  hereunder or waiver
of any  default  by Moadel  shall  operate  as a waiver of any other or  further
exercise of such right or power of any further default.

         9.5 Agreement Continuing.  This Agreement shall constitute a continuing
agreement,  applying to all future as well as existing transactions,  whether or
not of the  character  contemplated  at the date of this  Agreement,  and if all
transactions between Secured Party and Moadel shall be closed at any time, shall
be equally applicable to any new transactions thereafter.

         9.6 Definitions. Unless the context indicated otherwise, definitions in
the Texas Business and Commerce Code ("Texas UCC") apply to words and phrases in
this Agreement; if Texas UCC definitions conflict, Chapter 9 definitions apply.

         9.7 Miscellaneous. In this Agreement, whenever the context so requires,
the neuter gender  includes the masculine and feminine,  and the singular number
includes  the plural and vice  versa.  The  headings  of  paragraphs  herein are
inserted only for convenience and shall in no way define,  describe or limit the
scope of intent of any  provisions  of this  Agreement.  No  change,  amendment,
modification,  cancellation,  or  discharge of any  provision of this  Agreement
shall be valid unless consented to in writing by Secured Party.

         9.8 Assignment of Secured  Party's  Interest.  Secured Party shall have
the right to assign all or any portion of its rights in this  Agreement  without
approval or consent.  Moadel  acknowledges  that Secured Party intends to make a
collateral  assignment of its rights under this Agreement for the benefit of one
or more of its  lenders.  Moadel may not  assign  this  Agreement  or any of its
rights or  obligations  hereunder  without the express prior written  consent of
Secured Party in each instance.

     9.9 Applicable  Laws.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE  WITH THE LAWS OF THE STATE OF TEXAS AND THE  APPLICABLE  LAWS OF THE
UNITED STATES OF AMERICA.

         9.10 ENTIRE AGREEMENT. THIS AGREEMENT, THE LOAN AGREEMENT, THE NOTE AND
THE  CONTRIBUTION  AGREEMENT  (AND THE OTHER  AGREEMENTS  CONTEMPLATED  THEREIN)
REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY
EVIDENCE  OF  PRIOR,  CONTEMPORANEOUS,  OR  SUBSEQUENT  ORAL  AGREEMENTS  OF THE
PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

         9.11   Counterparts.   This   Agreement  may  be  executed  in  several
counterparts,  each of  which  shall  constitute  an  original  and all of which
together  shall  constitute  one and the same  instrument.  Any party hereto may
execute this Agreement by signing any one counterpart.

                            [Signature page follows]


<PAGE>


S-1

                                SIGNATURE PAGE TO

                        ASSIGNMENT AND SECURITY AGREEMENT

         IN WITNESS WHEREOF, the undersigned has executed this consent as of the
date first above written.

SECURED PARTY:                         Prime Medical Services, Inc.

                                       ------------------------------------
                                       Teena Belcik, Treasurer

MOADEL:

                                       --------------------------------
                                       Ken Moadel, M.D.