[1] UCL, Gastroenterol, Welwyn Garden City, Herts, England
[2] Kings Coll London, London, England
[3] Univ Hosp Nantes, Nantes, France
[4] Glasgow Royal Infirm, Glasgow, Lanark, Scotland
[5] AMC Netherlands, Amsterdam, Netherlands
[6] Tubingen Univ Hosp, Tubingen, Germany
[7] Horst Schmidt Kliniken, Wiesbaden, Germany