1 Department of Gastroenterology, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, PR China.
2 Division of General Internal Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA.
3 Department of Infectious Diseases, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, PR China; National & Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, PR China; Key Laboratory of Environment and Genes Related to Diseases, Xi'an Jiaotong University, Ministry of Education of China, Xi'an, PR China. Electronic address: jifanpu1979@163.com.