1. Department of Orthopedics, Tianjin Medical University General Hospital, Tianjin 300052, China
2. School of Medicine, Nankai University, Tianjin 300071, China
3. Tianjin Medical Universtiy, Tianjin 300070, China
4. Laboratory of Cerebrovascular Research, Department of Surgical Sciences, Anesthesiology and Intensive Care Medicine, University Hospital, Uppsala University, Frödingsgatan 12, 75421 Uppsala, Sweden