1. Department of Science and Gerontology, Medical Centre Hospital of President's Affairs Administration of the Republic of Kazakhstan, Astana, Republic of Kazakhstan.
2. Asfendiyarov Kazakh National Medical University, Almaty, Republic of Kazakhstan.
3. Department of Biology, Karaganda Medical University, Karaganda, Republic of Kazakhstan.
4. Medical Centre Hospital of President's Affairs Administration of the Republic of Kazakhstan, Astana, Republic of Kazakhstan.