1. From the Division of Cardiovascular Diseases (E.H.Y., G.W.B., G.P., C.S.R., A.L.), Department of Laboratory Medicine and Pathology (J.P.M., S.J.H.), Division of Biostatistics (R.J.L.), and Division of Nephrology and Hypertension (L.O.L.), Mayo College of Medicine, Rochester, Minn.