[1] Einstein Med Ctr, Div Gastroenterol, Philadelphia, PA USA
[2] Stanford Univ, Sch Med, Div Gastroenterol & Hepatol, Stanford, CA 94305 USA
[3] Baylor Coll Med, Div Gastroenterol, Houston, TX 77030 USA
[4] Michael E DeBakey VA Med Ctr, Houston, TX USA