1. Department of Internal Medicine, Gyeongsang National University Changwon Hospital, Gyeongsang National University College of Medicine, Changwon, Gyeongsangnam-do, Korea
2. Division of Gastroenterology, Department of Internal Medicine, Chonnam National University Medical School, Gwangju, Korea
3. Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, MN, USA