1. From the Critical Care Medicine Department (M.T.G.), Warren G. Magnuson Clinical Center, National Institutes of Health; Cardiovascular Branch (M.T.G.), National Heart, Lung, and Blood Institute, National Institutes of Health; Laboratory of Chemical Biology (M.T.G., A.N.S.), National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md.