1. Department of Gastroenterology, The Third Xiangya Hospital, Central South University, Changsha 410078, China
2. Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang 421001, China
3. Xiangya School of Medicine, Central South University, 172 Tongzipo Road, Changsha 410078, China
4. Hengyang Medical School, The First Affiliated Hospital, University of South China, Hengyang 421001, China