1. Laboratory of Clinical Investigation (C.W.C., J.O.O., O.D.C., J.M.E.), Maryland 21225
2. Department of Molecular Science and Technology (W.K.), Ajou University, Suwon 443–749, South Korea
3. Translational Gerontology Branch (L.F.), National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21225