1. Department of Chemistry and Biochemistry & Physics and Biophysics, University of Medicine-Pleven, 1 Kliment Ohridski Street, 5800 Pleven, Bulgaria
2. Department of Pediatrics, University of Medicine-Pleven, 1 Kliment Ohridski Street, 5800 Pleven, Bulgaria
3. Department of Hygiene and Ecology, Sumy State University, Medical Institute, 31 Sanatornaya Street, Sumy 40007, Ukraine
4. Department of Pediatrics with Medical Genetics, Sumy State University, Medical Institute, 31 Sanatornaya Street, Sumy 40007, Ukraine