For many years, the Tannenbaum lab has been interested in the formation, distribution, and metabolism of nitrate, nitrite, and N-nitroso compounds. This work led to their discovery of the endogenous synthesis of nitrogen oxides and eventually the discovery of nitric oxide as a biological molecule. At present the laboratory is conducting research on the pathophysiological consequences of nitric oxide and its oxidation products. This encompasses cell-mediated nitrosation, free-radical reactions, and oxidation. Of particular interest is the nature of chemical damage to DNA and its genotoxic consequences. From a health point of view this is important for the inflammatory state and for various infections and diseases that increase the risk of cancer. The Tannenbaum group is also interested in the inhibition of these reactions by antioxidants and other substances that offer protection from oxidative stress.