[1] Univ Verona, Div Gastroenterol, Azienda Osped Univ Integrata Verona, Valeggio S M Hosp, I-37067 Verona, Italy
[2] Univ N Carolina, Div Gastroenterol & Hepatol, Chapel Hill, NC 27516 USA
[3] Univ N Carolina, Ctr Funct Gastrointestinal & Motil Disorders, Chapel Hill, NC 27516 USA
[4] Asola Gen Hosp, Dept Surg & Orthoped, Gen Surg Unit, I-46041 Asola, Mantova, Italy