Document:

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                                                                    EXHIBIT 10.4

                              EMPLOYMENT AGREEMENT

    This is an EMPLOYMENT AGREEMENT "Agreement" effective as of January 21,
1999 ("Effective Date"), between ELIZABETH HOUGEN, an individual ("Employee"),
and MOLECULAR BIOSYSTEMS, INC., a Delaware corporation ("the Company").

    1.   EMPLOYMENT.

         a. POSITION. The Company agrees to employ Employee as its CHIEF
FINANCIAL OFFICER AND EXECUTIVE DIRECTOR OF FINANCE.

         b. DUTIES. Employee shall diligently, and to the best of her ability,
perform all such duties incident to her position and use her best efforts to
promote the interests of the Company.

         c. TIME TO BE DEVOTED TO EMPLOYMENT. Employee shall devote her full
time and energy to the business of the Company and shall not be engaged in any
competitive business activity without the express written consent of the
Company. Employee hereby represents that she is not a party to any agreement
which would be an impediment to entering into this Employment Agreement and that
she is permitted to enter into this Employment Agreement and perform the
obligations hereunder.

         d. AT-WILL EMPLOYMENT. Employee shall be employed on an at-will basis
and may terminate her employment and may be terminated from her employment at
any time with or without cause, subject to the severance payment provisions set
forth in paragraphs 14 and 16 below.

    2.   COMPENSATION AND BENEFITS.

         a. ANNUAL SALARY. In consideration of and as compensation for the
services agreed to be performed by Employee hereunder, the Company agrees to pay
Employee, as of the Effective Date of this Agreement, an annual Base Salary of
$125,000, payable in accordance with the Company's regular payroll schedule,
less applicable withholdings and deductions. Employee `s annual Base Salary is
subject to being increased as part of the Company's annual salary review
process.. If Employee is an Officer of the Company, changes to Base Salary must
be approved by the Board of Directors of the Company (the "Board").

         b. PARTICIPATION IN BENEFIT PLANS. Employee shall be entitled to
participate in any vacation or other benefit plan, to the extent eligible, that
is generally available to the other employees of the Company at the same level
as Employee. The Company reserves the right to amend, modify or terminate any
employee benefits at any time for any reason.
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         c. REIMBURSEMENT OF EXPENSES. The Company shall reimburse Employee for
all reasonable business expenses incurred by Employee on behalf of the Company
provided that: (i) such reasonable expenses are ordinary and necessary business
expenses incurred on behalf of the Company, and (ii) Employee provides the
Company with itemized accounts, receipts and other documentation for such
reasonable expenses as are reasonably required by the Company.

    3.   DEFINITIONS. The following definitions shall apply with respect to this
agreement.

         a. BASE SALARY means the Employee's annual salary; it shall not include
overtime pay, commissions or any other benefits and special allowances for which
the Employee is eligible (e.g., bonuses). If Employee's annual salary is
adjusted following the Effective Date of this Agreement, the adjusted annual
salary would then represent Employee's Base Salary. "Weekly Salary" shall mean
the Base Salary divided by fifty-two. "Monthly Salary" shall mean Base Salary
divided by 12.

         b. CHANGE OF CONTROL shall mean a change in ownership or control of the
Company effected through any of the following transactions:

           (1) a merger, consolidation or reorganization approved by the
Company's stockholders, unless securities representing more than fifty percent
(50%) of the total combined voting power of the voting securities of the
successor corporation are immediately thereafter beneficially owned, directly or
indirectly and in substantially the same proportion, by the persons who
beneficially owned the Company's outstanding voting securities immediately prior
to such transaction, or

           (2) any stockholder-approved transfer or other disposition of all or
substantially all of the Company's assets, or

           (3) the acquisition, directly or indirectly by any person or related
group of persons (other than the Company or a person that directly or indirectly
controls, is controlled by, or is under common control with, the Company), of
beneficial ownership (within the meaning of Rule 13d3 of the 1934 Act) of
securities possessing more than fifty percent (50%) of the total combined voting
power of the Company's outstanding securities pursuant to a tender or exchange
offer made directly to the Company's stockholders, or

           (4) a change in the composition of the Board over a period of
thirty-six (36) consecutive months or less such that a majority of the Board
members ceases, by reason of one or more contested elections for Board
membership, to be comprised of individuals who either (A) have been Board
members continuously since the beginning of such period or (B) have been elected
or nominated for election as Board members during such period by at least a
majority of the Board members described in clause (A) who were still in office
at the time the Board approved such election or nomination.

         c. CONSTRUCTIVE TERMINATION means within two years after a Change of
Control during which two-year period any of the following events take place AND
Employee gives written notice of her intent to resign her employment with the
Company and said

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resignation is submitted within thirty (30) days of the event : (i) a reduction
in the Base Salary of the Employee of more than fifteen percent (15%); (ii) a
relocation (or demand for relocation) of Employee's place of employment to a
location more than fifty (50) miles from Employee's current place of employment;
(iii) a significant or material reduction in Employee's job duties or level of
responsibility.

         d. 1934 ACT means the Securities Exchange Act of 1934, as amended, and
the rules and regulations promulgated thereunder.

         e. TERMINATION FOR CAUSE means a termination of Employee's employment
by the Company due to the Employee's:

           (1) Misconduct that has a material adverse effect on the Company's
operations, prospects, reputation or business;

           (2) Conviction of a felony;

           (3) Act of fraud against, or theft of property belonging to, the
Company; or

           (4) Gross negligence or the repeated failure of Employee to perform
her duties and responsibilities to the reasonable satisfaction of the Board or
superior after written notice of such failure, or any breach by Employee of her
fiduciary duties to the Company or any breach by Employee of her confidentiality
or proprietary information agreement with the Company.

         f. TERMINATION WITHOUT CAUSE means a termination of Employee's
 employment by the Company for any reason other than those specified in
subparagraph 3.e.(1) through (4) above.

         g. DISABILITY means that as a result of any physical or mental injury
or disability, Employee is unable to perform the essential functions of her job,
with or without reasonable accommodation. A notice will be issued when the
Company has reasonably determined that Employee has become unable to perform
substantially her services and duties hereunder with or without reasonable
accommodation because of any physical or mental injury or disability, and that
it is reasonably likely that she will not be able to resume substantially
performing her services and duties on substantially the terms and conditions as
set forth in this Employment Agreement.

    4. EMPLOYMENT. The Company shall be entitled to all of the benefits and
profits arising from or incident to the work, services and advice rendered by
the Employee relating to the work performed for the Company. The Employee shall
make all information available to the Company that relates to the Company's
business of which she has any knowledge and shall not use any such information
or the benefits of any such information for her personal profit or that of any
third party. The Employee agrees to use her best efforts to promote the
interests of the Company including, where appropriate, the publication of
articles in medical and scientific journals and the participation in medical and
scientific seminars and symposiums

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relating to the business and affairs of the Company and/or her research efforts
performed for and on behalf of the Company.

    5. DISCLOSURES. Employee shall promptly disclose in writing to the officials
designated by the Company to receive such disclosures, complete information
concerning each and every invention, discovery, improvement, device, design,
apparatus, practice, process, method or product (hereinafter referred to as
"Inventions"), whether Employee considers them patentable or not, made,
developed, perfected, devised, conceived or reduced to practice by Employee,
either solely or in collaboration with others, during the period of Employee's
employment by the Company, and up to and including a period of twelve (12)
months after termination of employment, whether or not during regular working
hours, relating either directly or indirectly to the business, products,
practices or techniques of the Company or to the Company's actual or
demonstrably anticipated research or development, or resulting from any work
performed by Employee for the Company or with the equipment, supplies,
facilities or confidential information of the Company.

    6. CONFIDENTIALITY. Employee recognizes that her employment with the Company
will involve contact with information of substantial value to the Company, which
is not generally known in the trade and which gives the Company an advantage
over its competitors who do not know or use it, including but not limited to
techniques, designs, drawings, processes, inventions, developments, equipment,
prototypes, sales and customer information, and business and financial
information, relating to the business, products, practices or techniques of the
Company (hereinafter referred to as "Confidential Information"). Employee shall
at all times regard and preserve as confidential such Confidential Information
obtained by Employee from whatever source and shall not, either during
Employee's employment or thereafter, publish or disclose any part of such
Confidential Information in any manner, or use the same except on behalf of the
Company, without the prior written consent of the Company. Further, Employee
shall, during her employment and thereafter, refrain from any acts or omissions
that would reduce the value of such Confidential Information to the Company.

    7. ASSIGNMENT OF RIGHTS. Employee hereby agrees that any Inventions made,
developed, perfected, devised, conceived or reduced to practice by Employee
during the period of her employment by the Company, and any other Inventions
made, developed, perfected, devised, conceived or reduced to practice by
Employee during said period of twelve (12) months after termination of her
employment if based upon the Confidential Information of the Company, relating
either directly or indirectly to the business, products, practices or techniques
of the Company or to the Company's actual or demonstrably anticipated research
or development, or resulting from any work performed by Employee for the Company
or with the equipment, supplies, facilities or Confidential Information of the
Company, are the sole property of the Company, and hereby assigns and agrees to
assign to the Company, its successors and assigns, all of my right, title and
interest in and to said Inventions, and any patent applications or Letters
Patent thereon.

                                  NOTIFICATION

                  THIS AGREEMENT DOES NOT APPLY TO AN INVENTION FOR WHICH NO
EQUIPMENT, SUPPLIES, FACILITY, OR TRADE SECRET INFORMATION OF THE COMPANY WAS
USED AND WHICH WAS

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DEVELOPED ENTIRELY ON EMPLOYEE'S OWN TIME, AND (a) WHICH DOES NOT RELATE (1) TO
THE BUSINESS OF THE COMPANY OR (2) TO THE COMPANY'S ACTUAL OR DEMONSTRABLY
ANTICIPATED RESEARCH OR DEVELOPMENT, OR (b) WHICH DOES NOT RESULT FROM ANY WORK
PERFORMED BY EMPLOYEE FOR THE COMPANY, AS DEFINED AND PROVIDED BY SECTION 2870
OF THE CALIFORNIA LABOR CODE.

    8. COVENANT OF COOPERATION. Employee shall, at any time during employment or
thereafter, upon request and without further compensation therefor, but with all
reasonable expenses incurred by Employee to be reimbursed, do all lawful acts,
including but not limited to the execution of papers and oaths, the giving of
testimony, and the obtaining of evidence that in the opinion of the Company, its
successors or assigns, may be necessary or desirable for obtaining, sustaining,
reissuing or enforcing Letters Patent in the United States and throughout the
world for said Inventions, and for perfecting, recording or maintaining the
title of the Company, its successors and assigns, to said Inventions and to any
patent applications made and any Letters Patent granted for said Inventions in
the United States and throughout the world.

    9. PATENT ENFORCEMENT. The Company shall have the sole discretion whether to
obtain, maintain, modify or enforce any domestic or foreign patent for said
Inventions assigned to the Company pursuant to this Agreement. The Company is
free to enter into any licensing or assignment agreement with any third party or
to use whatever means it deems best to develop, promote or market said
Inventions assigned to the Company pursuant to this Agreement or any domestic or
foreign patent thereof.

    10. CLAIMS BY THIRD PARTY. As to any Inventions which were made, developed,
perfected, devised, conceived or reduced to practice by Employee during the
period of her employment by the Company, and up to and including a period of
twelve (12) months after termination of her employment, but which are claimed
for any reason to belong to an entity or person other than the Company, Employee
will promptly disclose the same in writing to the Company and shall not disclose
the same to others if the Company, within twenty (20) days thereafter, shall
claim ownership of such Inventions under the terms of this Agreement.

    11. RECORD KEEPING. Employee shall keep complete, accurate and authentic
accounts, notes, data and records of any and all of said Inventions in the
manner and form requested by the Company. Such accounts, notes, data and
records, including all copies thereof, shall be the property of the Company, and
upon its request, Employee will promptly surrender the same to it, or if not
previously surrendered, Employee will promptly surrender the same to the Company
at the conclusion of her employment.

    12. RECORDS PROPERTY OF COMPANY. Employee agrees that all accounts, notes,
data sketches, drawings and other documents and records, and all material and
physical items of any kind, including all reproductions and copies thereof,
which relate in any way to the business, products, practices or techniques of
the Company or contain Confidential Information, made by Employee or that come
into Employee's possession by reason of her employment are the property of the
Company and shall be promptly surrendered to the Company at the conclusion of
Employee's employment.

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    13. NON-SOLICITATION. During Employee's employment with the Company and for
one (1) year thereafter, Employee will not solicit any employee of the Company
to leave the Company for any reason or to accept employment with any other
company. As part of this restriction, Employee will not interview any employee
of the Company or provide any input to any third party regarding any such person
for the purpose of offering such person employment elsewhere during the period
in question. However, this obligation shall not affect any responsibility
Employee may have as an employee of the Company with respect to the bona fide
hiring and firing of Company personnel.

    14. SEVERANCE PAYMENTS AND OTHER BENEFITS IN THE EVENT OF TERMINATION OF
EMPLOYMENT FOLLOWING A CHANGE OF CONTROL.

          a. In the event that either of the following two events occur within
two years after a Change of Control, the Company will provide the following
payment and benefits to Employee: (i) Employee's employment is terminated by the
Company Without Cause, or (ii) Employee's employment terminates as a result of a
Constructive Termination:

             (1) The Company shall make the following payments to Employee:

                  (A) ACCRUED SALARY AND BENEFITS. The Company shall pay
Employee's Base Salary through the effective date of termination of Employee's
Employment. In addition to the Severance Payments payable to an eligible
employee as described below, such employee shall receive the following: (i)
payment for accrued but unused vacation time; and (ii) group health coverage,
including eligible medical, dental and vision insurance through the last day of
the calendar month during which the termination occurs (group health coverage
after such date being governed by COBRA.)

                  (B) SEVERANCE PAYMENTS. The Company shall pay to Employee an
amount equal to 1.5 times the sum of the following: (a) her Base Salary in
effect immediately prior to the Change of Control and (b) a payment equal to the
higher of (i) 100% of Employee's target bonus as determined under the Company's
incentive compensation plan or (ii) an average of the last three actual bonuses
awarded to Employee. If the Company has not implemented an annual incentive
compensation plan for the current year, as referred to in the foregoing
sentence, then the amount determined under (ii) shall govern.

                  (C) MANNER OF PAYMENT. Severance Payments may be paid in
accordance with regular payroll periods, in a single lump sum payment, or any
combination thereof, as deemed appropriate by the Company. Taxes and other
appropriate deductions will be withheld; however, 401k contributions will not be
allowed.

             (2) The Company shall provide the following benefits to Employee:

                  (A) COBRA. An eligible Employee's existing coverage under the
Company's group health plan (and, if applicable, the existing group health
coverage for eligible dependents) will end on the last day of the month in which
the eligible Employee's employment terminates. The eligible Employee and her
eligible dependents may then be eligible

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to elect temporary continuation coverage under the Company's group health plan
in accordance with the Consolidated Omnibus Budget Reconciliation Act of 1985,
as amended ("COBRA"). The eligible Employee (and, if applicable, her eligible
dependents) will be provided with a COBRA election form and notice which
describe her rights to continuation coverage under COBRA. If an eligible
Employee elects COBRA continuation coverage, then the Company will pay for COBRA
coverage (such payments shall not include COBRA coverage with respect to the
Company's Section 125 health care reimbursement plan) for eighteen (18) months.
After such period of Company-paid coverage, the eligible employee (and, if
applicable, her eligible dependents) may continue COBRA coverage at her own
expense in accordance with COBRA. No provision of this agreement will affect the
continuation coverage rules under COBRA. Therefore, the period during which the
eligible employee must elect to continue the Company's group health plan
coverage under COBRA, the length of time during which COBRA coverage will be
made available to the eligible employee, and all the eligible employee's other
rights and obligations under COBRA will be applied in the same manner that such
rules would apply in the absence of this Plan. In the event, however, an
Employee becomes eligible for benefits under another plan prior to the
expiration of the period in which the Company is paying benefit premiums, the
Company shall no longer be obligated to pay such benefit premiums. The Employee
is required to notify the Company of eligibility for benefits under another plan
and is expected to enroll in the new group plan at the first eligible
opportunity unless Employee chooses, at Employee's sole expense, to continue
COBRA benefits through the Company. If Employee fails to notify the Company of
Employee's eligibility for alternative benefits, the Company shall have the
right to discontinue payment of COBRA premiums upon thirty (30) days notice to
Employee. In no event shall a cash payment be made to Employee in lieu of the
payment of COBRA premiums. The payment of COBRA premiums by the Company shall
not extend the maximum eligible COBRA coverage period.

                  (B) OUTPLACEMENT SERVICES. The Company will make available to
Employee, upon her request, outplacement services provided by a reputable
outplacement counselor selected by the Company for a period of six months
following termination. The Company will assume the cost of all such outplacement
services. In no event will a cash payment be made in lieu of outplacement
benefits.

    15. ACCELERATION OF STOCK OPTIONS IN THE EVENT OF A CHANGE OF CONTROL. In
the event of a Change of Control (whether or not followed by termination of
Employee's employment), all stock options under any Company stock option plan
which Employee holds at the time of such Change of Control shall become fully
"vested" (i.e., immediately exercisable). The Company shall also extend the
period of exercisability of those stock options to the maximum of four years, or
the natural expiration of the stock options, whichever is earlier.

    16. SEVERANCE PAYMENTS AND OTHER BENEFITS IN THE EVENT OF TERMINATION OTHER
THAN FOLLOWING A CHANGE OF CONTROL.

         a. In the event Employee's employment is terminated Without Cause other
than within two (2) years following a Change in Control, the Company shall
provide the payments and other benefits specified below to Employee:

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   (1)   The Company shall make the following payments to Employee:

         (A) ACCRUED SALARY AND BENEFITS. The Company shall pay Employee's Base
Salary through the effective date of termination of Employee's Employment. In
addition, employee shall receive the following: (i) payment for accrued but
unused vacation time; and (ii) group health coverage, including eligible
medical, dental and vision insurance through the last day of the calendar month
during which the termination occurs (group health coverage after such date being
governed by COBRA.)

         (B) SEVERANCE PAYMENTS. The Company shall pay to Employee a severance
payment equal to twelve (12) months of Employee's Monthly Salary, in effect
immediately prior to termination. This twelve (12) month period will be referred
to as the "Severance Period."

         (C) MANNER OF PAYMENT. These Severance Payments may be paid in
accordance with regular payroll periods over the duration of the Severance
Period, in a single lump sum, or any combination thereof, as deemed appropriate
by the Company. Taxes and other appropriate deductions will be withheld however,
401(k) contributions will not be allowed.

   (2)   The Company shall provide the following benefits to Employee

         (A) COBRA. An eligible Employee's existing coverage under the Company's
group health plan (and, if applicable, the existing group health coverage for
eligible dependents) will end on the last day of the month in which the eligible
Employee's employment terminates. The eligible Employee and her eligible
dependents may then be eligible to elect temporary continuation coverage under
the Company's group health plan in accordance with the Consolidated Omnibus
Budget Reconciliation Act of 1985, as amended ("COBRA"). The eligible Employee
(and, if applicable, her eligible dependents) will be provided with a COBRA
election form and notice which describe her rights to continuation coverage
under COBRA. If an eligible Employee elects COBRA continuation coverage, then
the Company will pay for COBRA coverage (such payments shall not include COBRA
coverage with respect to the Company's Section 125 health care reimbursement
plan) for the Severance Period. After such period of Company-paid coverage, the
eligible employee (and, if applicable, her eligible dependents) may continue
COBRA coverage at her own expense in accordance with COBRA. No provision of this
agreement will affect the continuation coverage rules under COBRA. Therefore,
the period during which the eligible employee must elect to continue the
Company's group health plan coverage under COBRA, the length of time during
which COBRA coverage will be made available to the eligible employee, and all
the eligible employee's other rights and obligations under COBRA will be applied
in the same manner that such rules would apply in the absence of this Plan. In
the event, however, an Employee becomes eligible for benefits under another plan
prior to the expiration of the period in which the Company is paying benefit
premiums, the Company shall no longer be obligated to pay such benefit premiums.
The Employee is required to notify the Company of eligibility for benefits under
another plan and is expected to enroll in the new group plan at the first
eligible opportunity unless Employee

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chooses, at Employee's sole expense, to continue COBRA benefits through the
Company. If the Employee fails to notify the Company of Employee's eligibility
for alternative benefits, the Company shall have the right to discontinue
payment of COBRA premiums upon thirty (30) days notice to Employee. In no event
shall a cash payment be made to eligible employees in lieu of the payment of
COBRA premiums. The payment of COBRA premiums by the Company shall not extend
the maximum eligible COBRA coverage period.

                  (B) OUTPLACEMENT. The Company will make available to Employee,
upon her request, outplacement services provided by a reputable outplacement
counselor selected by the Company for a period of six months following
termination. The Company will assume the cost of all such outplacement services.
In no event will a cash payment be made in lieu of outplacement benefits.

IN NO EVENT SHALL EMPLOYEE BE ENTITLED TO OR RECEIVE SEVERANCE BENEFITS UNDER
BOTH THIS PARAGRAPH 16 AND PARAGRAPH 14. Similarly, if Employee is eligible to
receive severance benefits under any other severance plan created by the Company
then it will reduce dollar for dollar any benefit due under this Agreement.

    17. SECTION 280G LIMITATION ON SEVERANCE PAYMENTS. The Severance Payments as
described in Paragraph 14(1)(B) of this Agreement shall be reduced as necessary
so that the present value, as determined in accordance Section 280G(d)(4) of
the Internal Revenue Code, of the sum of (i) the Severance Payments and (ii) all
other payments, if any, that must be taken into account for purposes of
computation under Section 280G(b)(2)(A)(ii) of the Internal Revenue Code in
respect of Employee does not exceed 2.99 times Employee's base amount, as "base
amount" is defined in Section 280G(b)(3) of the Internal Revenue Code .

    18. RETENTION BONUS PROGRAM. Employee will continue to participate in the
Retention Package program as explained in the memorandum to Employee dated
December 3, 1998.

    19. RESIGNATION, DEATH OR DISABILITY. Employee will not be entitled to any
Severance Benefits or Severance Payments under Paragraphs 14 or 16, or under any
other plan, or any other provision of this Agreement, if her employment is
terminated by the Company for Cause or if her employment terminates due to
disability, death or resignation (other than a resignation which constitutes a
CONSTRUCTIVE TERMINATION).

    20. EXCLUSIVITY. Employee shall not, while employed by the Company engage in
any other employment or business venture for her account or on behalf of others
that relates, directly or indirectly, to the business and affairs of the Company
without the prior written consent of the Company.

    21. PROHIBITION AGAINST ASSIGNMENT. Employee agrees that this Agreement and
the rights, interests and benefits hereunder shall not be assigned, transferred,
pledged or hypothecated in any way by Employee or any executor, administrator,
heir, legatee, distributee or any other person claiming under Employee by virtue
of this Agreement and shall not be subject to execution, attachment or similar
process. Any attempt to assign, transfer, pledge or hypothecate or otherwise
dispose of this Agreement or of such rights, interests and benefits

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contrary to the foregoing provisions, or the levy of any attachment or similar
process thereon shall be null and void and without effect and shall relieve the
Company of any and all liability hereunder.

    22. NOTICE. Any and all notices, designations, consents, offers, acceptances
or any other communication provided for herein shall be given in writing by
registered or certified mail, return receipt requested, which shall be
addressed, in the case of the Company, to its office in San Diego, California,
and in Employee's case to her last known place of residence as reflected on the
Company's records.

    23. ENTIRE AGREEMENT. This Agreement, and any stock option or stock purchase
agreements between the Employee and the Company, constitute the entire agreement
between Employee and the Company and contains all of the agreements between the
parties with respect to the subject matter hereof; this Agreement supersedes any
and all other agreements, either oral or in writing, between the parties with
respect to the subject matter hereof.

    24. BINDING EFFECT. This Agreement shall be binding upon and inure to the
benefit of Employee and the Company and their respective heirs, legal
representatives, executors, administrators, and successors.

    25. NO OTHER AGREEMENTS. Employee affirms that Employee has no agreement
with any other party that would preclude her compliance with her obligations
under this Agreement as set forth above.

    26. GOVERNING LAW. This Agreement shall be subject to and governed by the
laws of the State of California.

    27. AMENDMENT OF AGREEMENT. No change or modification of this Agreement
shall be valid unless the same is in writing and signed by Employee and the
Company. No waiver of any provision of this Agreement shall be valid unless in
writing and signed by the person or party to be charged.

    28. SEVERABILITY. If any portion or portions of this Agreement shall be, for
any reason, deemed to be invalid or unenforceable, the remaining portion or
portions shall nevertheless be valid, enforceable and carried into effect,
unless to do so would clearly violate the present legal and valid intention of
the parties hereto.

    29. BREACH. In the event either party breaches this Agreement and the other
party prevails in an action to enforce the terms of this Agreement, the losing
party agrees to pay to the prevailing party all reasonable attorneys' fees and
costs incurred by the prevailing party in prosecuting such action, and all
damages suffered by the prevailing party.

    30. HEADINGS. The headings of this Agreement are inserted for convenience
only and are not to be considered in construction of the provisions hereof.

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    31. WAIVER OR BREACH. The waiver by either of the parties hereto of any
breach of any provision hereof shall not be construed to be a waiver of any
succeeding breach of that provision or a waiver of any other provision of this
Agreement.

    32. ARBITRATION OF DISPUTES. Any dispute arising under this Agreement shall
be resolved through final and binding arbitration conducted pursuant to the
rules of the American Arbitration Association. This shall be in lieu of any
right to a jury trial, which right is expressly waived.

    33. GENERIC DRUG ENFORCEMENT ACT CERTIFICATION. The undersigned, certifies
that she (1) has never been charged with or convicted of a federal felony for
conduct relating to the development, approval, or regulation of any drug product
or device regulated by the United States Food and Drug Administration, and (2)
has never been debarred or subject to a debarment proceeding under the Generic
Drug Enforcement Act of 1992.

    (THIS SECTION HAS BEEN INTENTIONALLY LEFT BLANK FOR FORMATTING REASONS.)

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            WHEREAS, the parties have executed this Agreement as of the date
first above written.

                                    MOLECULAR BIOSYSTEMS, INC.

                                    By:
                                       -----------------------------------------
                                          Officer of Molecular Biosystems, Inc.

                                    By:
                                       -----------------------------------------
                                          Elizabeth Hougen

                                       12<PAGE>

EXHIBIT 4.1

                                [Front of Certificate]
                   Not valid unless countersigned by transfer agent
                 Incorporated Under the Laws of the State of Delaware
                                             CUSIP NO. 629300 10 4
                                       NMXS.com
Number                                            Shares
                      Authorized common stock: 50,000,000 shares
                              Par Value: $.001 per share

THIS CERTIFIES THAT

IS THE RECORD HOLDER OF

                        Shares of NMXS.COM, INC. Common Stock
transferable on the books of the Corporation in person or by duly authorized
attorney upon surrender of this Certificate properly endorsed.  This Certificate
is not valid until countersigned by the Transfer Agent and registered by the
Registrar.

     Witness the facsimile seal of the Corporation and the facsimile signature
of its duly authorized officers.
Dated:

/s/ Teresa Dickey                            /s/ Richard Govatski
Secretary                                    President

                               NMXS.com, Inc.
                                 Corporate
                                    Seal
                                  Delaware

Interwest Transfer Co., Inc., P.O. Box 17136/Salt Lake City, Utah 84117
                                        Countersigned & Registered

                                [Back of Certificate]
NOTICE:   Signature must be guaranteed by a firm which is a member of a
          registered national stock exchange, or by a bank (other than a saving
          bank), or a trust company.  The following abbreviations, when used in
          the inscription on the face of this certificate, shall be construed as
          though they were written out in full according to applicable laws or
          regulations.

TEN COM   as tenants in common          UNI GIFT MIN ACT . . . Custodian . . .
TEN ENT   as tenants by the entireties                 (Cust)         (Minor)
JT TEN    as joint tenants with right of          under Uniform Gifts to Minors
          survivorship and not as                 Act . .  . . . . . . . . .
          tenants in common                                  (State)

<PAGE>

         Additional abbreviations may also be used though not in the above list.

     For Value Received, _____________________ hereby sell, assign and transfer
unto

Please insert social security or other
  identifying number of assignee

       _______________________________________________________________________
   (Please print or typewrite name and address, including zip code, of assignee)
       _______________________________________________________________________
       _______________________________________________________________________
       ______________________________________________________ Shares of the
capital stock represented by the within certificate, and do hereby irrevocably
constitute and appoint _________________ Attorney to transfer the said stock on
the books of the within named Corporation with full power of substitution in the
premises.

Dated

     Notice:   The signature of this assignment must correspond with the name as
               written upon the face of the certificate in every particular
               without alteration or enlargement or any change whatever

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