Objective To construct eukaryotic expression bicistron plasmid vector pcDNA3.1-hOPG,and to detect the expression of the plasmid in vitro.Methods hOPG cDNA fragment was extracted from plasmid MGC:29565,amplified by PCR,and inserted into pcDNA3.1(-)vector,then identified by restriction endonuclease digestion and nucleotide sequencing.C2C12 cells were transfected with the plasmid using Lipofectamine 2000.The expression of OPG protein was detected by immunohistochemistry techniques and bone wafer pit assay.Results The constructed recombinant plasmid contained the sequence of hOPG gene.After transfection with the plasmid,active OPG protein could be expressed in C2C12 cells.Conclusion The constructed eukaryotic expression bicistron plasmid vector pcDNA3.1-hOPG can express OPG in vitro,which is the basis for further study on the treatment of bone absorption caused by abnormal activity of osteoclasts.

OBJECTIVESr-HA, a new type of hydroxyapatite biomaterial, was implanted into animals to study the bioreaction and character, which would be helpful for the further clinical applications in the future.

METHODSTotally 24 rabbits were divided into 3 groups. The bone defect of 6 mm x 12 mm x 4 mm was made at both mandibular angles of rabbits and Sr-HA of different proportion (10%, 5%, 0) was applied to reform the defects. One group of animals were killed randomly at 1, 3 and 6 months after operation to evaluate the material biological compatibility using anatomic, X-ray examination, histological and ECT methods.

RESULTSThe histological photographs showed that Sr-HA caused little infection around implanted area and, almost was not repulsed by hosts. With the degradation of biomaterial, there was more apparent new bone growth in the area around Sr-HA than that around HA and some ossification can be found in soft tissue nearby. Also a tight osteointegrity was gradually got after the operation, according to the results of X-ray and, the border between Sr-HA and bone was hardly discovered at the 6th month after the operation. A more obvious nuclide assembling was observed at the side of Sr-HA by ECT images. With the biodegradation of Sr-HA, more new bone was intruded into the spare space of the biomaterial.

CONCLUSIONSr-HA has better biocompatibility and higher biodegradation than that of pure HA. It holds an excellent osteoinductivity and fair osteoconductivity to some degree too. So a more satisfying effect of bone defect rehabilitation was gained with the increasing new bone depositing in the free space of the material, when it degraded gradually.

Animals ; Biocompatible Materials ; Biodegradation, Environmental ; Bone Substitutes ; Hydroxyapatites ; chemistry ; pharmacology ; Implants, Experimental ; Mandible ; surgery ; Osteogenesis ; physiology ; Rabbits ; Strontium ; chemistry ; pharmacology