1. Department of Gastroenterology, The Second Affiliated Hospital of Xi'an Jiaotong University, No. 157, Xiwu Road, Xi'an, Shaanxi, 710004, China
2. Department of Occupational and Environmental Health, Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi, 710061, China