1. Department of Doctoral Studies, Riga Stradins University, Riga, LV 1007, Latvia
2. Zemgale Health Centre, Jelgava, LV 3001, Latvia
3. Faculty of Medicine, Department of Human Physiology and Biochemistry, Riga Stradins University, Riga, LV 1007, Latvia
4. Faculty of Medicine, Department of Internal Diseases, Riga Stradins University, Riga, LV 1002, Latvia
5. Department of Clinical and Experimental Medicine, Occupational Medicine, University Hospital ‘Policlinico-Vittorio Emanuele’, University of Catania, I-95123 Catania, Italy
6. Newton Lewis Institute-ISR - Life Science Park, San Gwann 3000, Malta