RT Journal Article SR Electronic T1 Early surgical intervention in ulcerative colitis JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 308 OP 309 DO 10.1136/gut.2003.001727 VO 53 IS 2 A1 M A Kamm YR 2004 UL http://gut.bmj.com/content/53/2/308.abstract AB