1. Division of Gastroenterology, Department of Internal Medicine, East Carolina University, Greenville, NC, USA;
2. Gastroenterology and Hepatology Section, University of Pennsylvania, Philadelphia, PA, USA;
3. Division of Gastroenterology, Department of Internal Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA;
4. Gastroenterology and Hepatology Section, Baylor College of Medicine, Houston, TX, USA