[1] Stanford Univ, Sch Med, Div Gastroenterol & Hepatol, 300 Pasteur Dr, Stanford, CA 94304 USA
[2] St Christophers Hosp Children, Dept Pediat, Philadelphia, PA USA
[3] Texas Tech Univ, Hlth Sci Ctr, Dept Internal Med, Lubbock, TX USA
[4] Univ Arizona, Coll Med, Dept Med, Div Gastroenterol & Hepatol, Phoenix, AZ USA
[5] Banner Univ, Dept Internal Med, Div Gastroenterol & Hepatol, Med Ctr, Phoenix, AZ USA