1. From the Division of Clinical Pharmacology (J.W., S.R.T., A.K., D.W.T., M.A.S., L.X., M.S.M., W.C., D.G.H), and Departments of Medicine and Pharmacology (J.W., D.G.H.), Vanderbilt University, Nashville, TN; and Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Egypt (M.A.S.).