1. Medical Faculty, University of Nis; Department of Internal Medicine; Zorana Djindjica 81 Nis Serbia 18000
2. Copenhagen Trial Unit, Centre for Clinical Intervention Research, Department 3344, Rigshospitalet, Copenhagen University Hospital; The Cochrane Hepato-Biliary Group; Blegdamsvej 9 Copenhagen Denmark DK-2100
3. Gentofte University Hospital; Department of Internal Medicine; Niels Andersensvej 65 Hellerup Denmark 2900
4. Ospedale V.Cervello; Divisione di Medicina; Via Trabucco 180 Palermo Italy I-90146