Sim Sai Tin1, Viroj Wiwanitkit2. 1. Medical Center, Shantou, China. Electronic address: simsaitin@hotmail.com. 2. Visiting Professor, Hainan Medical University, China; Visiting Professor, Faculty of Medicine, University of Nis, Serbia; Adjunct Professor, Joseph Ayo Babalola University, Nigeria; Honorary Professor, Dr DY Patil Medical University, India; Professor, Senior Expert, Surin Rajabhat University, Thailand.