1. Department of Medicine; Liver Center and Gastroenterology Division; Beth Israel Deaconess Medical Center; Harvard Medical School and Harvard Digestive Diseases Center; Boston MA USA
2. Department of Internal Medicine; Division of Gastroenterology and Hepatology; Saint Louis University School of Medicine; St. Louis MO USA
3. Clinica Medica “A. Murri”; Department of Biomedical Sciences and Human Oncology; University of Bari Medical School; Bari Italy