Note 7 - Notes Payable

3 Months Ended

Mar. 31, 2019

Notes to Financial Statements

Debt Disclosure [Text Block]

7.

     Notes Payable

On

February 28, 2018,

we entered into a Senior Note Purchase Agreement with Georgia Research Alliance, Inc. (GRA) pursuant to which we issued a

five

-year Senior Promissory Note (the “GRA Note”) to GRA in exchange for

$50,000.

The GRA Note bears an annual interest rate of

5%,

payable monthly, with principal repayments beginning in the

second

year. Principal repayments are expected to be

$8,333

for the remainder of

2019,

$12,500

in

2020,

2021

and

2022,

and

$2,083

in

2023.

In connection with the GRA Note, we also issued to GRA a

five

-year warrant to purchase

358

shares of our common stock. Interest expense related to the GRA Note for the

three

-month periods ended

March 31, 2019

and

2018

was

$621

and

$208,

respectively.

On

December 27, 2018,

we issued short-term non-interest-bearing Term Promissory Notes (the “Term Notes”) to

two

current investors in exchange for an aggregate of

$250,000.

In connection with the Term Notes, we also issued to the investors

three

-year warrants to purchase an aggregate of

20,000

shares of our common stock. In

February 2019,

the Term Notes were cancelled in exchange for shares of our convertible preferred stock (see Note

9

).