Yo, Chung-Il, Faculty of Life Science, Kim Il Sung University, Pyongyang, Democratic People’s Republic of Korea. Yo, Chung-Il, Kim Il Sung University , Pyongyang, Democratic People’s Republic of Korea. Yu, Hyang Suk , Department of Apparatus Diagnostics. Hospital of Pyongyang University of Medical Sciences, Pyongyang, Democratic People’s Republic of Korea. Yu, Kang , Department of Endocrinology & Metabolism, Pyongyang University of Medical Sciences, Ryonhwa-dong, Central District, Pyongyang, Democratic People’s Republic of Korea. Yu, Kang , Pyongyang University of Medical Sciences, Ryonhwa-dong, Central District, Pyongyang, Democratic People’s Republic of Korea. Yu, Nam, Department of Gastroenterology, Hospital of Pyongyang University of Medical Science, Democratic People’s Republic of Korea. Yu, Nam, Department of Gastroenterology, Pyongyang University of Medical Science, Democratic People’s Republic of Korea. Yun, Hyon Il, Pyongyang University of Medical Sciences Yun, Yong Gun, Department of Pathology, Oncology Institute, Academy of Medical Sciences, DPR Korea.