1 Department of Gastroenterology, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, P. R. China.
2 Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, P. R. China.
3 Department of Small Bowel Endoscopy, the Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, P. R. China.
4 Center for Inflammatory Bowel Diseases, Columbia University Irving Medical Center-New York Presbyterian Hospital, New York, USA.