1. From the Cardiorenal Research Laboratory (P.M.M., A.C., F.L.M., M.M.R., J.C.B.), Division of Cardiovascular Diseases (R.J.R., A.C., M.M.R., J.C.B.), and Department of Biostatistics (L.H.U., D.W.M., S.J.J.), Mayo Clinic and Foundation, Rochester, Minn; and Stanley J. Sarnoff Endowment for Cardiovascular Science (P.M.M.), Great Falls, Va.