1. Gastroklinik, Private Gastroenterological Practice, 8810 Horgen, Switzerland
2. Department of Gastroenterology, University Hospital Zurich, 8091 Zurich, Switzerland
3. Division of Gastroenterology and Hepatology, Medical University Department, Kantonsspital Aarau, 5001 Aarau, Switzerland
4. Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, 54642 Thessaloniki, Macedonia, Greece
5. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, 8091 Zurich, Switzerland
6. First Laboratory of Pharmacology, School of Medicine, Aristotle University of Thessaloniki, 54124 Thessaloniki, Macedonia, Greece
7. Pancreaticobiliary Medicine Unit, University College London Hospitals (UCLH), London NW1 2BU, UK
8. Gastrocentro Plus, Private Gastroenterological Practice, 6900 Lugano, Switzerland
9. Gastroenterologische Gruppenpraxis, Private Gastroenterological Practice, 3011 Bern, Switzerland
10. School of Healthcare Sciences, Midwifery Department, University of West Macedonia, 50100 Kozani, Macedonia, Greece
11. Department of Gastroenterology, 401 General Military Hospital of Athens, 11525 Athens, Attica, Greece