[1] Brown Univ, Warren Alpert Med Sch, Div Pediat, Brown Ctr Study Children Risk, Providence, RI 02905 USA
[2] Brown Univ, Women & Infants Hosp, Providence, RI 02905 USA
[3] Univ Maryland, Ctr Substance Abuse Res, College Pk, MD 20742 USA
[4] Univ Hawaii, John A Burns Sch Med, Honolulu, HI 96822 USA
[5] Univ Oklahoma, Coll Med, Oklahoma City, OK 73190 USA
[6] Univ Calif Los Angeles, David Geffen Sch Med, Los Angeles Biomed Inst Harbor, Los Angeles, CA 90095 USA
[7] Blank Childrens Hosp Iowa Hlth Syst, Des Moines, IA USA
[8] Natl Inst Drug Abuse, Intramural Res Program, Baltimore, MD USA