1. a College of Public Health and College of Chemistry & Chemical Engineering, University of South China , Hengyang , Hunan , P.R. China
2. b School of Public Health, Guangdong Medical College , Dongguan , Guangdong , P.R. China
3. c School of Public Health and Tropical Medicine, Southern Medical University , Guangzhou , Guangdong , P.R. China
4. d Departments of Physiology and Functional Genomics , Shands Cancer Center, UF Genetics Institute and McKnight Brain Institute, University of Florida , Gainesville , FL , USA