1. Department of Pathology, San Bo Brain Hospital, Capital Medical University, Haidian, Beijng, P. R. China
2. Department of Neurosurgery, San Bo Brain Hospital, Capital Medical University, Haidian, Beijng, P. R. China
3. The Second Hospital of Shanxi Medical University, Taiyuan, P. R. China
4. Beijing Health Vocational College, Xicheng, Beijing, P. R. China
5. Department of Pathology, Capital Medical University, Beijing, P.R. China