1. From the Division of General Internal Medicine (G.E.M.) and the Cardiovascular Division (C.W.B., D.J.M., C.M.A., J.N.C.), Department of Medicine, University of Minnesota Medical School, Minneapolis, Minn; the Department of Epidemiology (S.P.G.) and the Department of Laboratory Medicine and Pathology (S.M.F.), University of Minnesota, Minneapolis.