1 Department of Gastroenterology, The Shanghai Tenth People's Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, P. R. China.
2 Department of General Surgery (Colorectal Surgery), The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, P. R. China; Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Guangdong Institute of Gastroenterology, Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, P. R. China.