[1] NHLBI, Div Epidemiol & Clin Applicat, Rockville, MD USA
[2] Westat Corp, Rockville, MD 20850 USA
[3] Maryland Med Res Inst, Baltimore, MD USA
[4] Childrens Hosp, Med Ctr, Div Adolescent Med, Cincinnati, OH 45229 USA
[5] Univ Calif Berkeley, Dept Nutr Sci, Berkeley, CA 94720 USA