1. Gastroenterology Department, Centro Hospitalar São João, Porto, Portugal
2. Faculty of Medicine of the University of Porto, Porto, Portugal
3. Digestive Health Institute, Swedish Medical Center, Seattle, Washington, USA
4. Division of Gastroenterology, Stanford University, California, USA
5. Division of Gastroenterology, Department of Medicine, Olive View-UCLA Medical Center, Sylmar, CA, USA
6. UCLA Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA