Objective　To investigate morphological changes of endothelial cells after nordihydroguaiaretic acid (NDGA) treatment in vitro. Methods　The morphological changes of human umbilical vein endothelial cells (HUVEC) cell line ECV-304 and the cell apoptosis rate in sub-G0 phase were observed with invert, light and electron microscope and flow cytometry after NDGA treatment at different concentrations or with PBS (0.01 mol/L) as control. Results　①After the treatment of NDGA at 50～200 μmol/L for 1～3 d or up to 8 d at 100 μmol/L, ECV-304 cells tended to elongate into a shuttle-like sparse appearance and those in mitosis were decreased, indicating the suppression of cell proliferation. All these alteration was in a time-and dose-dependent manner. ②NDGA-treated ECV-304 cells displayed morphological features of apoptosis, especially at the 48th h after the treatment. With flow cytometry, the cells in sub-G0 phase were significantly increased, and reached its peak at hour 12 (20.42%) after NDGA treatment. In addition, the degeneration and necrosis of ECV-304 cells were related to the concentrations of NDGA. Conclusion　NDGA can inhibit the proliferation and growth of endothhelial cells, and induce apopotosis, which might also inhibit angiogenesis.

Objective　 To investigate the profile of telomerase and telomerase RNA expression in nasopharyngeal carcinogenesis (NPC) induced by N,N'dinitrosopi perazine (DNP) and examined histolofically. Methods Nasopharyngeal carcinomas o f rats were induced by DNP and examined histologically. PCR-ELISA and nested R T -PCR were used to assay telomerase and telomerase RNA expression at different s tages in the nasopharyngeal tissues of rats. Results　 During the carcinogenesis p rocess, telomerase activity increased along with the formation of a nasopharynge al carcinoma. Telomerase expression was positively related with nasopharyngeal c arcinogenesis. Telomerase RNA expression was present and did not change during t he NPC process. Expression of telomease RNA was earlier than telomerase activat ion. Telomerase activation and telomerase RNA expressin were also detected in th e pre-cancerous nasopharyngeal lesions. Conclusion　 Telomerase activation may p articipate in the onset and progression of NPC, and is an early step in NPC.

Objective:To report our experience in diagnosis and treatment of posterior atlantoaxial dislocation with odontoid retrolisthesis.Methods:A retrospective study was conducted of the 5 patients who had been treated from July 2012 to August 2018 at Department of Orthopaedics, General Hospital of Southern Theater Command for posterior atlantoaxial dislocation. They were 4 men and one woman, aged from 34 to 67 years (average, 47 years). All of them had a history of trauma. Of them, 4 were complicated with odontoid fracture and one with congenital free os odontoideum. Their posterior atlantoaxial dislocation ranged from 3 to 9 mm (average, 6 mm). By the American Spinal Injury Association (ASIA) grading system, their preoperative spinal injury was rated as grade B in one, as grade C in 3 cases and as grade D in one. All the 5 patients underwent skull traction at 10° flexion. Surgical trans-oralpharyngeal atlantoaxial reduction and internal fixation was performed for the one patient whose reduction had not been achieved by traction while posterior atlantoaxial screw-rod fixation or anterior odontoid screwing was conducted for the 4 patients whose reduction had been achieved by traction. The distance of posterior atlantoaxial dislocation was measured to evaluate their reduction and ASIA grade system was used to assess their spinal function after operation.Results:The postoperative distance of posterior atlantoaxial dislocation was 0 mm, showing a reduction rate of 100%. The 5 patients were followed up for 6 to 36 months (average, 15 months). By the ASIA grade system, the postoperative functional recovery of the spine was grade D in 4 cases and grade C in one. No implant loosening or breakage occurred.Conclusion:As a kind of high-energy hyperextension injury, posterior atlantoaxial dislocation is rare in clinic, but an appropriate treatment can be adopted to deal with its different clinical types to achieve good outcomes.