1. Veterans Research and Education Foundation, Veterans Affairs Medical Center, Oklahoma City, Oklahoma
2. The First Affiliated Hospital of Xi’an Jiaotong University, Shannxi, China
3. Department of Physiology, University of Oklahoma, Oklahoma City, Oklahoma
4. Division of Gastroenterology and Hepatology, Johns Hopkins Center for Neurogastroenterology, Baltimore, Maryland
5. Department of Gastroenterology, Tianjin No. 254 Hospital, Tianjin, China