EXHIBIT 10.7
                                                                    ------------

                              AMENDED AND RESTATED
                                 PROMISSORY NOTE
$171,666.67                                                        JULY 31, 2001
                                  DALLAS, TEXAS


         FOR VALUE RECEIVED, the undersigned, MedSolutions, Inc., formerly known
as EnviroClean International, Inc. or Advanced EnviroTech Systems, Inc., a Texas
corporation  (the  "Maker"),  hereby  promises  to pay to the  order  of Mark M.
Altenau,  M. D.  ("Payee"),  at Dallas,  Texas,  or at such other address as the
holder of this Note may  designate  from time to time in writing  to Maker,  the
principal sum of ONE HUNDRED  SEVENTY ONE THOUSAND SIX HUNDRED SIXTY SIX DOLLARS
AND SIXTY-SEVEN CENTS ($171,666.67),  with said loan to bear interest at no more
than ten  percent  (10%) per  annum  and to be  payable  on July 31,  2002.  The
principal  amount  of this  Note  shall be due and  payable  July 31,  2002 (the
"Maturity Date"). No principal payments on this Note are allowed for a period of
twenty-four  (24) months  following  the original loan on July 31, 2000 or until
July 31,  2002.  The Payee has the  option to  convert  the loan  principal  and
accrued  interest  thereon  into shares of AES Common Stock par value $0.001 per
share at the rate of One dollar and Twenty Five cents ($1.25) per share.

         This Note is  collateralized  by the  so-called  "IMCO  Contract  being
negotiated  with the Kingdom of Saudi Arabia",  specifically  from the royalties
from the sale of an estimated  twenty (20)  EnviroClean  EC-500  Systems to said
customer  and by the  patented  technology  known  as  the  EnviroClean  Thermal
Oxidation  System and by all of the other tangible and  intangible  property and
assets of MedSolutions, Inc. and any subsidiary thereof.

         This Amended and  Restated  Promissory  Note and the  security  created
hereby shall  terminate as of the date on which the  obligations,  and any other
amounts  that the Maker may owe to the Payee as a result of this Note,  are paid
or renegotiated in writing.


         The makers, signers,  sureties,  guarantors, and endorsers of this Note
severally  waive  valuation  and  appraisal,  demand,  presentment,   notice  of
dishonor,  notice of intent to demand or accelerate  payment  hereof,  notice of
demand,  notice of acceleration,  diligence in collecting,  grace,  notice,  and
protest.  If this Note  shall be  collected  by legal  proceedings  or through a
probate or bankruptcy  court, or shall be placed in the hands of an attorney for
collection  after  default  or  maturity,  the Maker  agrees to pay all costs of
collection, including reasonable attorneys' fees and expenses and court costs.

         Interest on the indebtedness evidenced by this Note is hereby expressly
limited so that in no contingency or event  whatsoever,  whether by acceleration
of the maturity of this Note or otherwise,  shall the interest  contracted  for,
charged,  or received by the Payee  exceed the highest  lawful rate  permissible
under applicable law. If any circumstances whatsoever shall involve transcending
the limit of validity  prescribed by law, then, ipso facto, the obligation to be
fulfilled  shall be reduced to the limit of such validity,  and if from any such
circumstances  the Payee  shall ever  receive  anything  of value as interest or
deemed  interest  by  applicable  law  under  this  Note or any  other  document
evidencing,  securing, or pertaining to the indebtedness  evidenced hereby, such
amount that would be excessive interest shall be applied to the reduction of the
principal  amount owing under this Note or on account of any other  indebtedness
of the  Maker to the  Payee,  and not to the  payment  of  interest,  or if such
excessive interest exceeds the unpaid balance of principal of this Note and such
other  indebtedness,  such excess shall be refunded to the Maker. In determining
whether or not the interest paid or payable with respect to any  indebtedness of
the Maker to the Payee,  under any  specific  contingency,  exceeds  the highest
lawful rate, the Maker and the Payee shall,  to the maximum extent  permitted by

<PAGE>

applicable law, (a) characterize any non-principal  payment as an expense,  fee,
or premium rather than as interest;  (b) exclude  voluntary  prepayments and the
effects thereof; (c) amortize, prorate, allocate, and spread the total amount of
interest  throughout the full term of such  indebtedness so that the actual rate
of interest on account of such  indebtedness  does not exceed the highest lawful
rate permitted by applicable law; and/or (d) allocate  interest between portions
of such  indebtedness,  to the end that no such portion shall bear interest at a
rate greater than the highest lawful rate permitted by applicable law. The terms
and  provisions  of this  paragraph  shall  control  and  supersede  every other
conflicting provision of this Note.

         The term  "applicable  law" means the  applicable  laws of the State of
Texas or applicable laws of the United States,  whichever laws allow the greater
rate of  interest,  as such laws now exist or may be  changed or amended or come
into effect in the future.

         THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED AND ENFORCED IN ACCORDANCE
WITH  THE  LAWS  OF THE  STATE  OF  TEXAS  APPLICABLE  TO  AGREEMENTS  EXECUTED,
DELIVERED,  AND PERFORMED IN THE CITY OF DALLAS,  DALLAS COUNTY,  TEXAS, WITHOUT
GIVING EFFECT TO THE CONFLICT OF LAWS RULES OR CHOICE OF LAWS RULES THEREOF.

         EXECUTED effective as of the date first set forth above.

                                         MEDSOLUTIONS, INC.


                                         By:  /s/ MATTHEW FLEEGER
                                             -----------------------------------

                                         Name: Matthew Fleeger

                                         Title: President/CEO

/s/ MARK ALTENAU, M.D.
----------------------
Mark M. Altenau, M.D.