[1] Yale Univ, Sch Med, Dept Surg Gastroenterol, New Haven, CT 06520 USA
[2] Brown Univ, Rhode Isl Hosp, Providence, RI 02912 USA
[3] Harvard Univ, Massachusetts Gen Hosp, Dept Med, Gastrointestinal Unit, Boston, MA 02115 USA
[4] NIDDK, Digest Dis Branch, Bethesda, MD USA
[5] NCI, NIH, Bethesda, MD 20892 USA