Massimo Bellini1, Dario Gambaccini2, Gabrio Bassotti3. 1. Gastrointestinal Unit, Department of Gastroenterology, University of Pisa, Pisa, Italy. Electronic address: mbellini@med.unipi.it. 2. Gastrointestinal Unit, Department of Gastroenterology, University of Pisa, Pisa, Italy. 3. Gastroenterology & Hepatology Section, Department of Medicine, University of Perugia Medical School, Perugia, Italy.