[1] Olive View UCLA Med Ctr, Dept Med, Div Gastroenterol, 14445 Olive View Dr, Sylmar, CA 91342 USA
[2] Univ Penn, Div Gastroenterol, Philadelphia, PA 19104 USA
[3] Univ Calif Los Angeles, David Geffen Sch Med, Dept Med, Vatche & Tamar Manoukian Div Digest Dis, Los Angeles, CA 90095 USA
[4] Univ Penn, Dept Pathol & Lab Med, Philadelphia, PA USA
[5] Penn Presbyterian Med Ctr, 218 Wright Saunders Bldg,51 N 39th St, Philadelphia, PA 19104 USA