[The high level expression of CTLA-4/Ig fusion protein in CHO cell].

OBJECTIVE: To establish the basis in the function study and clinical application of the fusion protein of cytotoxic T lymphocyte antigen 4 CTLA-4 and IgG Crl (CTLA-4/Ig), by studying the expression of CTLA-4/Ig fusion protein in eukaryotic CHO cells and purifying CTLA-4/Ig fusion protein expressing in CHO cells. METHODS: The CHO/dhfr- cells were transfected with linearized plasmids of pMM-CTLA-4-IgG4/WG and pMMGR. The clones of CHO/pCTLA-4+/pMMGR+ were in suspension cultured in serum-free culture media. The expression level of CTLA-4/Ig fusion protein in cell culture media was detected through Western blot. The biological identification of relative molecular mass, purity and antigen specificity of the expressing CTLA-4/Ig fusion protein that have been purified with protein A affinity chromatography was studied by SDS-PAGE or Western blot respectively. RESULTS: The CHO cells that could steadily express at high level the CTLA-4/Ig fusion protein was selected for cloning. By SDS-PAGE for the CTLA-4/Ig fusion protein that have been purified with protein A affinity chromatography, a protein band was found to match well with the predicted relative molecular mass. This protein could specifically bind with human CTLA-4 monoclonal antibody. CONCLUSION: The CHO cells that can express steadily CTLA-4/Ig fusion protein that is of the bioactivity at high level are successfully obtained.

Effect of methylprednisolone on the activities of caspase-3, -6, -8 and -9 in rabbits with acute spinal cord injury.

The present study aimed to investigate the effect of methylprednisolone (MP) on the activities of caspase-3, -6, -8 and -9 in rabbits with acute spinal cord injury (ASCI) and to explore the mechanism underlying the antiapoptotic effect of MP on ASCI. Modified Allen's method was employed to establish the ASCI animal model. The animals were randomly divided into a sham (S; n=12), ASCI (C; n=36) and MP group (T; n=36). At 8, 24 and 72 h and 7, 14 and 28 days after ASCI, the animals were sacrificed and the spinal cord was collected. The absorbance (A) was measured with a microplate reader and the activities of caspase-3, -6, -8 and -9 were calculated followed by comparisons among the groups. In the S group, the activities of the four caspases were low. In the C and T groups, the caspase activities increased at 8 h after injury, peaked at 24 h and remained at a high level 3 days after injury. However, the caspase activities began to decrease at 7 days after injury and were significantly reduced at 14 and 28 days after ASCI. Furthermore, the caspase activities in the T group were markedly lower than those in the C group at 8 and 24 h and 3 and 7 days after surgery (P<0.05), but significant differences were not observed at 14 and 28 days after injury (P>0.05). In conclusion, MP exerted an antiapoptotic effect via inhibition of the activities of caspase-3, -6, -8 and -9 in an animal model of ASCI.

[Short-term therapeutic effect of posterior pedicle screw fixation for treatment of degenerative lumbar scoliosis].

OBJECTIVE: To evaluate the short-term outcomes of patients receiving orthopedic surgery with posterior pedicle screw fixation for degenerative lumbar scoliosis. METHODS: Between March, 2006 and August, 2009, 36 patients with degenerative lumbar scoliosis (19 males and 17 females) underwent procedures of decompression, bone implantation and pedicle screw fixation. Fifteen patients were also treated by PLIF and 21 cases received posterior-lateral fusion. The JOA scores, Oswestry disability index (ODI), and Cobb angle were recorded before and after the operation, and the surgical complications were also observed. RESULTS: The JOA scores increased significantly by 83.3% after the operation (P<0.05). The procedures resulted in significantly lowered ODI from (67.1∓11.4)% before the operation to (32.1∓10.8)% after the operation (P<0.01). A significant improvement of the coronal Cobb's angle was achieved after the operation (26.7° preoperatively vs 12.3° postoperatively, P<0.01), and the lordosis angle was improved from 10.7° to 36.6° after the operation (P<0.01). All the patients were followed up for 12 to 50 months (mean 38 months), and no implant loosening, displacement or fragmentation, or pseudarthrosis was found at the final follow-up. CONCLUSION: Posterior pedicle screw fixation shows good short-term therapeutic effect in treatment of degenerative lumbar scoliosis. Individualized surgical plans and adequate preoperative evaluation are keys to successful operations.