The Free Radical Core (FRC) will make state-of-the-art radical detection methodologies available to all of the investigators associated with the PPG. Multiple assays will be performed, wherever feasible, to provide rigorous identification and characterization of reactive oxygen and nitrogen species, their reactions and products. Following extensive discussions between Project Leaders and FRC research personnel, experimental protocols will be designed. In some instances, particularly in Electron Spin Resonance (ESR)-based protocols, the FRC staff will initially carry out the proposed work and subsequently train other research personnel in ESR. For other routine free radical analysis (i.e., TBARS_, the FRC personnel will advise the investigator on how to perform the experiments. The Free Radical Corre will provide the necessary technical facilities, custom- made free radical traps, and provide scientific expertise to pursue experiments in the following general areas: 1) Direct ESR detection of less reactive free radicals (e.g., ascorbate radical) and detection of more reactive and unstable free radicals (e.g., superoxide anion and hydroxyl radicals( by ESR spin- trapping using a variety of nitrone-based spin traps. 2) Detection of NO and NO-derived products (NO2-, NO3-, RSNO). 3) Detection of marker products of oxidation and nitration (e.g., dityrosine and nitrotyrosine) and lipid hydroperoxide/TBARS in peroxynitrite-mediated reactions. 4) HPLC detection of antioxidants (e.g., alpha-tocopherol) and their radical reaction products (e.g., alpha-tocopherylquinone). 5) Determination of cellular antioxidants (e.g., GSH) and anti-oxidant enzymes (GPx, SOD, catalase). In addition, the FRC will continue to refine and develop new assays for detection of ROS and RNS and synthesize novel radical traps that will enable project leads to pursue new research directions. The ultimate goal of Core B will be to ensure completions of the proposed aims in Projects 1-5 that require that above-mentioned facilities.