1. Institute of Clinical and Preventive Medicine, University of Latvia, LV-1586 Riga, Latvia
2. Riga East University Hospital, LV-1038 Riga, Latvia
3. Faculty of Residency, Riga Stradins University, LV-1007 Riga, Latvia
4. Institute of Chemistry, Jan Kochanowski University of Kielce, PL-25406 Kielce, Poland
5. Institute for Breath Research, University of Innsbruck, A-6850 Dornbirn, Austria
6. Laboratory of Medical Genomics, A.C.Camargo Cancer Center, Sao Paulo 01508-010, Brazil
7. Digestive Diseases Center GASTRO, LV-1079 Riga, Latvia
8. Faculty of Medicine, University of Latvia, LV-1586 Riga, Latvia