1. From the Cardiovascular Biology Laboratory, Harvard School of Public Health (N.E.S.S., L.C.F., C.-M.H., M.A.P., W.-S.L., W.O.E., M.-E.L., E.H.), the Department of Medicine, Harvard Medical School (N.E.S.S., M.A.P., M.-E.L., E.H.), and the Cardiovascular (N.E.S.S., M.-E.L.) and Pulmonary (M.A.P.) Divisions, Brigham and Women’s Hospital, Boston, Mass, and the Department of Biological Structure, University of Washington School of Medicine (E.H.S.), Seattle, Wash.