1. From the Division of Cardiovascular Surgery, Department of Surgery, (W.H., P.A., N.A.M., J.R. Frederick, J.R. Fitzpatrick, R.C.M., J.R.M., E.C.Y., J.W.M., Y.J.W.), and Penn Cardiovascular Institute (L.-J.Y.), University of Pennsylvania School of Medicine, Philadelphia, PA; Department of Chemistry (J.M.P.-A., J.G.S.), University of Pennsylvania School of Arts and Sciences, Philadelphia, PA; and Division of Cardiology (R.D.L.), Department of Medicine, Emory University School of Medicine, Atlanta, GA.