1. Department of Digestive Diseases, IRCCS Azienda Ospedaliero, Universitaria di Bologna, 40138 Bologna, Italy
2. Department of Medical and Surgical Sciences, University of Bologna, 40138 Bologna, Italy
3. Division of Gastroenterology and Digestive Endoscopy, Department of Medical Sciences, Central Hospital, Azienda Ospedaliera, 74100 Taranto, Italy