[1] Harvard Univ, Brigham & Womens Hosp, Div Prevent Med, Sch Med, Boston, MA 02215 USA
[2] Brown Univ, Sch Med, Providence, RI 02912 USA
[3] George Washington Univ, Sch Med, Washington, DC USA
[4] Univ Iowa, Iowa City, IA USA
[5] NHLBI, NIH, Bethesda, MD 20892 USA
[6] Albert Einstein Coll Med, Bronx, NY 10467 USA