aBoston University Chobanian & Avedisian School of Medicine

bVA Boston Healthcare System, Section of Gastroenterology and Hepatology, Boston, Massachusetts, USA

Correspondence to H. Christian Weber, MD, AGAF, FACG, Boston University Chobanian & Avedisian School of Medicine, Section of Gastroenterology & Hepatology, 650 Albany Street, EBRC, Room 810, Boston, MA 02118-2518, USA. Tel: +1 617 638 8329; fax: +1 617 638 7785; e-mail: [email protected]