Dr. Zheng Yong, Department of Gastroenterology, First Affiliated Hospital, Shihezi School of Medicine, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region 832008, China (Tel: 86-13579748283. Fax: 86- 993-2859284. Email: xueli 2006@163.com) Correspondenceto: Dr. Tian Dean, Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China (Tel: 86- 15927368783. Email: datian@tjh.tjmu.edu.cn);