1. From the Center for Systems Biology (J.L.F., M.N., R.W.), Massachusetts General Hospital and Harvard Medical School, Simches Research Building, Boston, Mass; Center for Molecular Imaging Research (J.L.F., M.N., D.E.S., R.W.), Massachusetts General Hospital and Harvard Medical School, Charlestown, Mass; and Cardiology Division (D.E.S.), Massachusetts General Hospital, Harvard Medical School, Boston, Mass.