1. From the Department of Medicine (N.I.S., T.I.P., J.R.O., B.D.M., A.R.S.), University of Maryland School of Medicine, Baltimore, Md; the Department of Medicine (R.K.), Rush Medical College, Chicago, Ill; the Department of Biology (I.G.I.), Valdosta State University, Georgia; the Department of Medicine (W.-C.H.), University of California, San Francisco; and the Geriatric Research and Education Clinical Center (A.R.S.), Veterans Administration Medical Center, Baltimore, Md.