In March 2002, we completed a follow-on offering of our common stock for approximately $21.3 million. At June 30, 2003, we had borrowings of approximately $3.6 million outstanding related to a loan which was entered into primarily for equipment financing. If we do not maintain minimum unrestricted cash, as defined in the loan agreement, equal to the greater of $35.0 million or twelve months’ cash needs (calculated by taking the trailing three months net cash used in operations multiplied by four), we are required to provide a cash security deposit or letter of credit equal to an amount defined in the loan agreement, not to exceed 50% of outstanding amounts on draws made in or subsequent to December 2000. As of December 31, 2001, and just prior to our March 2002 equity offering we did not maintain the minimum unrestricted cash defined in the loan agreement. We received a waiver from our lender regarding our noncompliance with this covenant for this period. Subsequent to March 31, 2002, we did not maintain the minimum cash defined in the loan agreement. We have also received written notice from the lender stating that the lender waived the financial covenant violation as a result of not maintaining a pledge of cash security deposit or letter or credit under this loan agreement for the period of noncompliance through June 19, 2002. On June 19, 2002, we obtained a letter of credit in the amount of approximately $2.7 million as required by the loan agreement, which was supported by a cash restriction on certain securities held by us. In June 2003, our letter of credit expired and the cash was converted to a security deposit held by the lender. As such, this cash restriction, in addition to cash restricted under two of our operating leases is reflected as restricted cash in the condensed consolidated balance sheet as of June 30, 2003 of $3.4 million, of which approximately $1.5 million is classified as a long term asset.
On May 10, 2001, we filed a Registration Statement on Form S-3 with the Securities and Exchange Commission. Subject to our ongoing obligations under the Securities Act of 1933, as amended, and the Securities Exchange Act of 1934, as amended, the Registration Statement permits us to offer and sell various types of securities, up to an aggregate value of approximately $75.0 million, of which approximately $16.8 million remains available for future use. The sale of common stock in June 2001 for gross proceeds of approximately $35.7 million was registered under this Registration Statement. The subsequent sale of common stock in February and March 2002 for gross proceeds of approximately $22.5 million was also registered under a Prospectus Supplement to this Registration Statement. The availability to offer and sell various types of securities under the shelf registration statement expired in May 2003.
As of June 30, 2003, we had approximately $15.7 million in cash and cash equivalents as compared to approximately $10.0 million as of December 31, 2002. Working capital increased to approximately $14.0 million at June 30, 2003 from approximately $9.5 million at December 31, 2002. This increase in working capital is due to the $16 million in financing which was completed on March 31, 2003.
Net cash used in operations for the six months ended June 30, 2003 was approximately $3.0 million compared with cash used in operations of approximately $20.8 million for the comparable period of the prior year. This significant decline in cash used in operations demonstrates the magnitude of cost savings we have achieved over the past year resulting from our divestitures and cost cutting efforts. Investing activities during the six months ended June 30, 2003 included capital expenditures of approximately $0.8 million. Financing activities during the six months ended June 30, 2003 primarily consisted of approximately $16.0 million of net proceeds from our offering of redeemable convertible preferred stock in March of 2003 and repayment of debt of approximately $7.0 million, which includes $5.2 million which was repaid on our $10 million credit facility.
We expect our restructuring efforts taken in 2002 and 2003 will continue to reduce future cash expenditures. We believe that the result of these efforts coupled with anticipated divestitures of certain non-core assets, expected increases in both revenues and gross margins in our remaining core business units and our financing in 2003 will enable us to operate our ongoing business activities until we reach operating profitability and positive cashflows, expected by the end of 2003.
We believe that our existing cash on hand, with the inclusion of the 2003 financing, the availability of our line of credit as described above, and proceeds from the expected sale of our Diagnostics business will be sufficient to fund our operations through at least December 31, 2003. We may need to access the capital markets for additional financing to operate our ongoing business activities after that time if our future results of operations fall below our expectations. We may be unable to raise additional funds or raise funds on terms that are acceptable to us. If future financing is not available to us, or is not available on terms acceptable to us, we may not be able to fund our future needs. If we raise funds through equity or convertible securities, our stockholders may experience dilution and our stock price may decline.