RT Journal Article SR Electronic T1 Reply JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 484 OP 484 DO 10.1136/gut.31.4.484 VO 31 IS 4 A1 McMahon, R F T A1 Babbs, C A1 Warnes, T W YR 1990 UL http://gut.bmj.com/content/31/4/484.abstract AB