Our total revenues, net income and fully diluted earnings per share in the first six months of 2009 included $8.2 million of one-time revenue associated with the renegotiation of our collaboration agreement with Novartis, as well as Tepnel's results of operations which were not included in the comparable prior year period. In contrast, the first six months of 2008 included $16.4 million of royalty and license revenue associated with the settlement payment received from Bayer (now Siemens Healthcare Diagnostics) which was recorded in the first quarter of 2008.
Acquisition of Tepnel Life Sciences plc In April 2009, we completed our acquisition of Tepnel. The acquisition was consummated pursuant to a court-sanctioned scheme of arrangement under Part 26 of the UK Companies Act 2006. As a result of the acquisition, Tepnel became a wholly owned subsidiary of Gen-Probe Incorporated.
Upon consummation of the acquisition, each issued ordinary share of Tepnel was cancelled and converted into the right to receive 27.1 pence in cash, or approximately $0.40 based on the exchange rate of £1 to $1.48 as of the closing date. In connection with the acquisition, the holders of issued and outstanding Tepnel capital stock, options and warrants received total net cash of approximately £92.8 million, or approximately $137.1 million based on the exchange rate of £1 to $1.48 as of the closing date. The acquisition was financed through amounts borrowed under a senior secured revolving credit facility established with Bank of America, N.A., or Bank of America.` Amended Collaboration Agreement with DiagnoCure Inc. In April 2009, we and DiagnoCure, Inc., or DiagnoCure, entered into an amendment to the License, Development and Cooperation Agreement originally signed by the parties on November 19, 2003.
Pursuant to the amendment, we agreed to use our commercially reasonable efforts to obtain United States Food and Drug Administration, or FDA, approval of specified PCA3 assays and to file an application with the FDA for regulatory approval of a PCA3 assay in the United States by a specified date. In addition, we agreed to make annual payments of $0.5 million to DiagnoCure until specific milestones are met. After our cumulative net sales of licensed products exceed $50.0 million, half of the annual payments may be applied against future royalties due and payable to DiagnoCure under our agreement with DiagnoCure.
In addition, pursuant to the terms of the amendment, in April 2009 we paid $5.0 million to purchase 4.9 million shares of newly issued DiagnoCure preferred stock, which is convertible, in whole or in part at our election, into DiagnoCure common stock.
Credit Agreement
In February 2009, we entered into a credit agreement with Bank of America, which provided for a one-year senior secured revolving credit facility in an amount of up to $180.0 million that is subject to a borrowing base formula. The revolving credit facility has a sub-limit for the issuance of letters of credit in a face amount of up to $10.0 million. Advances under the revolving credit facility are intended to be used to consummate our acquisition of Tepnel and for other general corporate purposes. At our option, loans accrue interest at a per annum rate based on, either: the base rate (the base rate is defined as the greatest of (i) the federal funds rate plus a margin equal to 0.50%, (ii) Bank of America's prime rate and (iii) the London Interbank Offered Rate, or LIBOR, plus a margin equal to 1.00%); or LIBOR plus a margin equal to 0.60%, in each case for interest periods of 1, 2, 3 or 6 months as selected by us. In connection with the credit agreement, we also entered into a security agreement, pursuant to which we secured our obligations under the credit agreement with a first priority security interest in the securities, cash and other investment property held in specified accounts maintained by Merrill Lynch, Pierce, Fenner & Smith Incorporated, an affiliate of Bank of America.
In March 2009, we borrowed $170.0 million under the revolving credit facility in anticipation of funding the acquisition of Tepnel. Also in March 2009, we amended the credit agreement with Bank of America to increase the amount that we may borrow from time to time under the credit agreement from $180.0 million to $250.0 million.
In April 2009, we borrowed an additional $70.0 million under the revolving credit facility with Bank of America and used approximately $137.1 million of such borrowings (based on the then applicable exchange rate) to fund our acquisition of Tepnel. As of June 30, 2009, the total principal amount outstanding under the revolving credit facility was $240.0 million.
In connection with the execution of the credit agreement with Bank of America, we terminated the commitments under our unsecured bank line of credit with Wells Fargo Bank, N.A., effective as of February 27, 2009. There were no amounts outstanding under this line of credit as of the termination date.

Corporate Collaboration with Novartis In January 2009, we entered into an agreement, referred to herein as Amendment No. 11, with Novartis to amend the June 11, 1998 collaboration agreement, or the 1998 Agreement, between the parties. The effective date of Amendment No. 11 is January 1, 2009. Amendment No. 11 extends to June 30, 2025 the term of our blood screening collaboration with Novartis under the 1998 Agreement. The 1998 Agreement was scheduled to expire by its terms in 2013.
The 1998 Agreement provided that we were solely responsible for manufacturing costs incurred in connection with the collaboration, while Novartis was responsible for sales and marketing expenses associated with the collaboration. Amendment No. 11 provides that, effective January 1, 2009, we will recover 50% of our cost of product sales incurred in connection with the collaboration, which is recorded in the form of revenue. In addition, we will receive a percentage of the blood screening assay revenue generated under the collaboration, as described below.
The 1998 Agreement provided that we share revenue from the sale of blood screening assays under the collaboration with Novartis. Under the terms of the 1998 Agreement, as previously amended, our share of revenue from any assay that included a test for HCV was 45.75%. Amendment No. 11 modifies our share of such revenues, initially reducing it to 44% in 2009. Our share of blood screening assay revenue increases in subsequent years as follows: 2010-2011, 46%; 2012-2013, 47%; 2014, 48%; and 2015, 50%. Our share of blood screening assay revenue is fixed at 50% from January 1, 2015 though the remainder of the amended term of the agreement. Under Amendment No. 11, our share of blood screening assay revenue from any assay that does not test for HCV remains at 50%. Amendment No. 11 also provides that Novartis will reduce the amount of time between product sales and payment of our share of blood screening assay revenue from 45 days to 30 days. This reduction in reporting time allowed us to eliminate one month of the reporting lag for net revenues resulting in an $8.2 million one-time benefit in the first quarter of 2009.
As part of Amendment No. 11, Novartis has agreed to provide certain funding to customize our Panther instrument, a fully automated molecular testing platform now in development, for use in the blood screening market. Novartis has also agreed to pay us a milestone payment upon the first commercial sale of the Panther instrument. The parties will equally share any profit attributable to Novartis' sale or lease of Panther instruments under the collaboration. The parties have also agreed to evaluate, using our technologies, the development of companion diagnostics for current or future Novartis medicines. Novartis has agreed to provide us with certain funding in support of initial research and development.
Stock Repurchase Program
In August 2008, our Board of Directors authorized the repurchase of up to $250.0 million of our common stock over the two years following adoption of the program, through negotiated or open market transactions. There is no minimum or maximum number of shares to be repurchased under the program. During the three months ended June 30, 2009, we repurchased and retired approximately 1,602,000 shares under this program at an average price of $43.66, or approximately $70.0 million in total. From its inception through June 30, 2009, we have repurchased and retired approximately 4,182,000 shares under this program at an average price of $43.17, or approximately $180.5 million in total. Critical accounting policies and estimates Our discussion and analysis of our financial condition and results of operations is based on our consolidated financial statements, which have been prepared in accordance with United States generally accepted accounting principles, or U.S. GAAP. The preparation of these consolidated financial statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses and the related disclosure of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, the collectability of accounts receivable, and the valuation of the following: stock-based compensation; marketable securities; equity investments in publicly and privately held companies; income tax; liabilities associated with employee benefit costs; inventories; goodwill and long-lived assets, including patent costs, capitalized software, purchased intangibles and licenses and manufacturing access fees. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, which form the basis for making judgments about the carrying values of assets and liabilities. Senior management has discussed the development, selection and disclosure of these estimates with the Audit Committee of our Board of Directors. Actual results may differ from these estimates.
We believe there have been no significant changes during the second quarter of 2009 to the items that we disclosed as our critical accounting policies and estimates in "Management's Discussion and Analysis of Financial Condition and Results of Operations" in our Annual Report on Form 10-K for the year ended December 31, 2008, except for the items discussed below.

Marketable securities
The primary objectives of our marketable security investment portfolio are liquidity and safety of principal. Investments are made with the goal of achieving the highest rate of return consistent with these two objectives. Our investment policy limits investments to certain types of debt and money market instruments issued by institutions primarily with investment grade credit ratings and places restrictions on maturities and concentration by type and issuer.
We periodically review our available-for-sale securities for other-than-temporary declines in fair value below the cost basis, or whenever events or circumstances indicate that the carrying amount of an asset may not be recoverable. When assessing marketable securities for other-than-temporary declines in value, we consider factors including: the significance of the decline in value compared to the cost basis; the underlying factors contributing to a decline in the prices of securities in a single asset class; how long the market value of the investment has been less than its cost basis; any market conditions that impact liquidity; the views of external investment managers; any news or financial information that has been released specific to the investee; and the outlook for the overall industry in which the investee operates.
We do not consider our investments in municipal securities with a current unrealized loss position to be other-than-temporarily impaired at June 30, 2009 since we do not intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost. However, investments in an unrealized loss position deemed to be temporary at June 30, 2009 that have a contractual maturity of greater than 12 months have been classified as non-current marketable securities under the caption "Marketable securities, net of current portion," reflecting our current intent and ability to hold such investments to maturity.
Adoption of recent accounting pronouncements EITF Issue No. 07-1
Effective January 1, 2009, we adopted Emerging Issues Task Force, or EITF, Issue No. 07-1, "Accounting for Collaborative Agreements Related to the Development and Commercialization of Intellectual Property." EITF Issue No. 07-1 defines collaborative agreements as a contractual arrangement in which the parties are active participants to the arrangement and are exposed to the significant risks and rewards that are dependent on the ultimate commercial success of the endeavor. Additionally, it requires that revenue generated and costs incurred on sales to third parties as it relates to a collaborative agreement be recognized as gross or net based on EITF Issue No. 99-19, "Reporting Revenue Gross as a Principal versus Net as an Agent." Essentially, this requires the party that is identified as the principal participant in a transaction to record the transaction on a gross basis in its financial statements. It also requires payments between participants to be accounted for in accordance with already existing generally accepted accounting principles, unless none exist, in which case a reasonable, rational, consistent method should be used. The adoption of this statement did not have an impact on our consolidated financial statements, as all agreements were in compliance with this standard prior to its adoption.
SFAS No. 160
Effective January 1, 2009, we adopted Statement of Financial Accounting Standards, or SFAS, No. 160, "Non-controlling Interests in Consolidated Financial Statements (an amendment of Accounting Research Bulletin No. 51)." SFAS No. 160 requires that non-controlling (minority) interests be reported as a component of equity, that net income attributable to the parent and to the non-controlling interest be separately identified in the income statement, that changes in a parent's ownership interest while the parent retains its controlling interest be accounted for as equity transactions, and that any retained non-controlling equity investment upon the deconsolidation of a subsidiary be initially measured at fair value. As of June 30, 2009, we did not have any consolidated subsidiaries in which we had a non-controlling interest, and therefore adoption of this statement did not have an impact on our consolidated financial statements.
SFAS No. 141(R)
Effective January 1, 2009, we adopted SFAS No. 141(R), "Business Combinations." SFAS No. 141(R) changes the requirements for an acquirer's recognition and measurement of the assets acquired and liabilities assumed in a business combination, including the treatment of contingent consideration, pre-acquisition contingencies, transaction costs, in-process research and development and restructuring costs. In addition, under SFAS No. 141(R), changes in an acquired entity's deferred tax assets and uncertain tax positions after the measurement period will impact income tax expense. See Note 2 - Business combination, of the Notes to the Consolidated Financial Statements included in Item 1 of Part I of this report for the impact of the adoption of SFAS No. 141(R) on our financial results as of June 30, 2009.

Results of Operations
Product Sales

(Dollars in millions)                Three Months Ended June 30,                                Six Months Ended June 30,
                          2009         2008         $ Change       % Change         2009         2008         $ Change       % Change
Clinical diagnostics     $  67.8      $  57.2      $     10.6             19 %     $ 127.4      $ 109.7      $     17.7             16 %
Blood screening             45.8         56.5           (10.7 )          (19 )%       98.7        105.5            (6.8 )           (6 )%
Research products and
services                     3.2            -             3.2            N/M           3.2            -             3.2            N/M

Product Sales            $ 116.8      $ 113.7      $      3.1              3 %     $ 229.3      $ 215.2      $     14.1              7 %

As a percent of total
revenues                      97 %         95 %                                         97 %         89 %

Our primary source of revenue comes from product sales, which consist primarily of the sale of clinical diagnostic and blood screening products in the United States and throughout the world. Our clinical diagnostic product sales consist primarily of our APTIMA, PACE, AccuProbe and Amplified Mycobacterium Tuberculosis Direct Test product lines, as well as sales of transplant diagnostics and genetic testing products acquired as part of our recent acquisition of Tepnel, which are primarily sold under the LIFEMATCH and Elucigene trademarks. The principal customers for our clinical diagnostics products include reference laboratories, public health institutions and hospitals. The blood screening assays and instruments we manufacture are marketed and distributed worldwide through our collaboration with Novartis under the Procleix and Ultrio trademarks.
We recognize product sales from the manufacture and shipment of tests for screening donated blood at the contractual transfer prices specified in our collaboration agreement with Novartis for sales to end-user blood bank facilities located in countries where our products have obtained governmental approvals. Blood screening product sales are then adjusted monthly corresponding to Novartis' payment to us of amounts reflecting our ultimate share of net revenue from sales by Novartis to the end user, less the transfer price revenues previously recorded. Net sales are ultimately equal to the sales of the assays by Novartis to third parties, less freight, duty and certain other adjustments specified in our collaboration agreement with Novartis multiplied by our share of the net revenue.
Product sales increased by 3% and 7% in the three and six months ended June 30, 2009, respectively, as compared to the same periods of 2008. In each case, the increase was primarily attributed to additional product sales as a . . .