1. Division of Gastroenterology, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States
2. Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States
3. Department of Medicine, University of California Los Angeles, Los Angeles, California, United States
4. Division of Gastroenterology, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, United States
5. Division of Gastroenterology, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, United States