1. From the Division of Cardiology, Department of Medicine, Johns Hopkins Medical Institutions, Baltimore (K.C., S.K.D., T.A., R.S.T., V.L.D., T.P.A., K.J., G.F.T., D.A.K.); Reproductive Biology and Medicine Branch, Section on Medical Neuroendocrinology, National Institute of Child Health and Human Development, Bethesda (E.W.L., K.P.); and Laboratory of Cardiovascular Science, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore (W.-Z.Z., R.-p.X.), Md.