[1] Univ Bern, Clin Rheumatol & Clin Immunol Allergol, CH-3010 Bern, Switzerland
[2] Harvard Univ, Sch Med, Massachusetts Gen Hosp, Gastrointestinal Unit, Boston, MA 02114 USA
[3] Harvard Univ, Sch Med, Massachusetts Gen Hosp, Dept Med, Boston, MA 02114 USA
[4] Harvard Univ, Sch Med, Partners AIDS Res Ctr, Boston, MA 02114 USA
[5] Osped Reg Lugano, Dept Med, CH-6903 Lugano, Switzerland