[1] Hannover Med Sch, Dept Gastroenterol Hepatol & Endocrinol, D-30625 Hannover, Germany
[2] Univ Dusseldorf, Dusseldorf, Germany
[3] Goethe Univ Frankfurt, Frankfurt, Germany
[4] Robert Koch Inst, D-1000 Berlin, Germany
[5] Univ Cologne, Cologne, Germany
[6] Ankara Univ, Sch Med, TR-06100 Ankara, Turkey
[7] Ufuk Univ, Sch Med, Ankara, Turkey
[8] Mem Hosp Istanbul, Istanbul, Turkey
[9] Uludag Univ, Sch Med, Bursa, Turkey
[10] Univ Larissa, Larisa, Greece