1. From Tufts University School of Medicine, Boston, MA (I.R.P., K.E.R., N.S.H.); ICON Clinical Research, San Francisco, CA (D.P.M., G.P.S.); Actelion Pharmaceuticals US Inc., South San Francisco, CA (M.S., W.W.B.); and Boston University School of Medicine, Boston, MA (H.W.F.).