1. From the Division of Cardiology (R.R.S., L.B., H.C.C., M.K.L., J.M.H., E. Messina, M.R.A., E. Marbán), Johns Hopkins University, Baltimore, Md, and Department of Experimental Medicine, Pasteur Institute, Cenci Bolognetti Foundation, University La Sapienza, Rome, Italy (L.B., E. Messina, A.G.).