[1] Massachusetts Gen Hosp, Gastrointestinal Unit, Boston, MA 02114 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Harvard Univ, Sch Publ Hlth, Ctr Biostat AIDS Res, Boston, MA 02115 USA
[4] Univ N Carolina, Chapel Hill, NC USA
[5] Case Western Reserve Univ, Cleveland, OH 44106 USA
[6] Tulane Univ, New Orleans, LA 70118 USA
[7] Univ Hawaii, Honolulu, HI 96822 USA
[8] ACTG Operat Ctr, Rockville, MD USA
[9] Univ Cincinnati, Cincinnati, OH USA