[1] Mayo Clin, Div Gastroenterol & Hepatol, Rochester, MN USA
[2] Imelda GI Clin Res Ctr, Bonheiden, Belgium
[3] Cleveland Clin Fdn, Cleveland, OH 44195 USA
[4] Manchester Royal Infirm, Manchester M13 9WL, Lancs, England
[5] Univ Bologna, Bologna, Italy