OBJECTIVE: To evaluate the curative effect and clinical significance of bone cement on coagulation functions during percutaneous vertebroplasty in patients with osteoporotic spinal compression fractures.METHODS: A total of 24 patients, comprising 18 females and 6 males, aged 69 years averagely (range 48-83 years), with 44 osteoporotic vertebral compression fractures underwent percutaneous vertebroplasty in Department of Spinal Surgery, Third Hospital of Hebei Medical University between December 2006 and December 2007. The fracture segment was within T_5-L_3 (20 thoracic vertebrae and 24 lumbar vertebrae). Under the guidance of C-arm fluoroscopy, bone marrow biopsy needle was inserted percutaneously via transpedicular way into the fractured vertebrae. Polymethylmethacrylate (PMMA, bone cement) was injected into the fractured vertebrae. The relative parameters were observed in all patients 10 minutes before, 10 minutes, 30 minutes, 1 hour, 2 hours and 3 hours after bone cement implantation, including prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB), plasma protamine paracoagulation test (3P test), and D-dipolymer (D-D). RESULTS: PT was decreased, and FIB, 3P test, D-D were increased 10 minutes after bone cement implantation in percutaneous vertebroplasty peaked at 1 hour and gradually decreased afterward; moreover, there were significant difference between bone cement preimplantation and 10 minutes, 30 minutes, 1 hour, 2 hours and 3 hours after bone cement implantation (P < 0.05), but no difference was observed in APTT and TT (P > 0.05). The influence of bone cement on the parameters was vanished in 3 hours after bone cement implantation, and all indexes were similar to pre-implantation (P > 0.05).CONCLUSION: Bone cement implantation causes temporal hypercoagulabale state in percutaneous vertebroplasty. It is important to monitor blood clotting state in 3 hours after bone cement implantation in order to avoid thrombus disease.

Objective To establish an efficient baculovirus-insect cell expression system for the production of human immunodeficiency virus-1 ( HIV-1 ) envelope glycoprotein gp120 and to evaluate the physiochemical properties, antigenicity and immunogenicity of the recombinant protein. Methods The gene encoding HIV-1 NL4-3 gp120 was cloned into the downstream of pH promoter of the baculovirus transfer vec-tor pAcgp67B to construct the recombinant transfer vector pAc-gp120. Expression of the protein of interest was induced in baculovirus-infected High FiveTM insect cells. ELISA, analytical ultracentrifugation and size-exclusion chromatography were carried out to characterize physicochemical properties of the expressed gp120 protein. Immunogenicity of the recombinant gp120 protein was analyzed by HIV neutralization assay after im-munizing BALB/c mice with it. Results The recombinant HIV-1 gp120 protein was successfully obtained from the established insect cell expression system with a purity of more than 90％ and a mean yield of 13 mg/L in four batches. That recombinant HIV-1 gp120 protein was characterized by homogeneity in solution and possessed a good immunoreactivity to neutralizing antibodies and antisera against HIV. Immunogenicity analysis in BALB/c mice demonstrated that the recombinant gp120 protein could induce effective immune re-sponses against HIV-1 NL4-3. Conclusion A simple and scalable approach to obtain homogeneous and im-munogenic HIV-1 gp120 antigen is successfully established, which will promote further investigation of HIV vaccine candidates.