[1] Univ Bologna, Dept Med & Surg Sci, I-40126 Bologna, Italy
[2] Gen Hosp, Dept Internal Med 2, Lecce, Italy
[3] Univ Milan, Dept Biomed & Clin Sci L Sacco, I-20122 Milan, Italy
[4] Univ Bologna, Dept Expt Diagnost & Specialist Med, I-40126 Bologna, Italy
[5] Univ Modena, Dept Pediat, I-41100 Modena, Italy
[6] Royal Free Hosp, UCL Inst Liver & Digest Hlth, London NW3 2QG, England