1 Division of Gastroenterology, Department of Medicine, Sepulveda Ambulatory Care Center, VAGLAHS and David Geffen School of Medicine at UCLA, North Hills and Los Angeles, California, USA.
2 Division of Gastroenterology, Department of Medicine, Sepulveda Ambulatory Care Center, VAGLAHS and David Geffen School of Medicine at UCLA, North Hills and Los Angeles, California, USA; Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shaanxi, China.