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BACKGROUND: Porous silicon carbide has excellent physical and chemical properties and can be used to repair complex shapes and long weight-bearing bone defects, but it has no biological activity and cannot promote bone remodeling and integration. OBJECTIVE: A tantalum (Ta) coating was deposited on the surface of the porous silicon carbide scaffold to evaluate its biological activity. METHODS: The chemical vapor deposition method was used to deposit a Ta coating on the surface of the porous silicon carbide scaffold. The optimal experimental parameters were explored by setting different gas reaction flow rates and temperatures. The Ta coating was prepared with the best experimental parameters to test the mechanical properties of porous Ta. Human osteoblasts were co-cultured with the Ta coating specimens, and were observed by scanning electron microscopy after 3 and 7 days of cultivation. RESULTS AND CONCLUSION: (1) After the optimization of experimental parameters, the best experimental conditions were controlled as follows: deposition temperature of 1 050 °C, hydrogen flow rate of 180 mL/min and chlorine flow rate of 100 mL/min. (2) The compressive strength of the Ta coated specimen was (61.4±3.2) MPa; the yield strength was (45.8±2.9) MPa; and the elastic modulus was 4.8 GPa. (3) Scanning electron microscopy demonstrated that after 3 days of co-cultivation, a large number of cells adhered to the surface of the porous silicon carbide scaffold that is coated with Ta and the porous structure. Some of the cells protruded from the pseudopod and were connected to each other. After 7 days of co-cultivation, the cell protrusions fused to form a sheet covering the surface of the porous Ta. In the porous structure, the cells protruded from the pseudopods, cross-linked to each other across the pores, secreted in the matrix, and coated the microparticle structure, gradually spreading in the pores. (4) The results show that the Ta coating on the surface of porous silicon carbide scaffold has good mechanical properties and biological activity.
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OBJECTIVE: To explore the effect of cadmium on bone formation and its mechanism in male mice. METHODS: i) The specific pathogen-free C57 BL/6 J wild-type male mice were divided into control group and cadmium exposure group, with 10 mice in each group. Mice in the cadmium exposure group were intraperitoneally injected with 2 mg/kg body weight cadmium chloride twice a week for eight weeks, and mice in the control group were intraperitoneally injected with the same amount of 0.9% sodium chloride solution. After that, the bone mineral density and bone microstructure of the femur of mice were detected by a high-resolution microcomputed tomography scanner. ii) Human SV40-transfected osteoblast cells(hFOB1.19) were divided into control group and cadmium exposure group. The cadmium exposure group was treated with 0.5 μmol/L cadmium chloride solution, cells in the control group were given an equal volume of α-low-limit minimal medium. After culture, the differentiation and mineralization ability of hFOB1.19 cells were analyzed by alkaline phosphatase(ALP) and alizarin red staining, respectively. Cell viability was examined by CCK-8 assay. The protein expression of Janus kinase 2(JAK2), total signal of transducers and activator of transcription 3(tSTAT3) and phosphorylated signal transducers and activator of transcription 3(pSTAT3) was detected by Western blotting. The expression of osteoblastic marker genes ALP, Runt-related transcription factor 2(RUNX2) and osteocalcin(OCN) was detected by real-time quantitative polymerase chain reaction.RESULTS: Compared with the control group, the average bone mineral density decreased(P<0.01), bone volume fraction decreased(P<0.05), the bone trabecula thickness became thinner(P<0.01), the number of bone trabecula decreased(P<0.05), trabecular bone spacing increased(P<0.05) in the femur of mice in cadmium exposure group. The viability of hFOB1.19 cells was decreased [(100.0±10.8)% vs(49.1±8.2)%, P<0.01]. The differentiation ability of osteoblasts was reduced and the mineralization was inhibited. The relative expression levels of JAK2 and pSTAT3 in cells decreased(all P<0.05) and the relative expression levels of osteoblast marker genes ALP, RUNX2 and OCN decreased(all P<0.01).CONCLUSION: Cadmium can induce mice bone loss, which may be due to its inhibition of osteoblastic function by reducing the expression of JAK2 and STAT3 proteins.
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BACKGROUND: At present, related finite element models have been used to simulate the femoral fracture, and the effects of loading rate, loading angle and cancellous bone on the fracture of hip have been discussed. However, the fracture simulation of trabecula is still lack of relevant research. OBJECTIVE: To simulate the biomechanical process of osteoporotic trabecular compression fracture in ovariectomized rats. METHODS: The right femur of ovariectomized rats was scanned at the distal end of femur by Micro-CT. The microstructure parameters and three-dimensional model of the region of interest of the rat femur were obtained. After geometric optimization in Geomagic Studio, they were pretreated in HyperMesh 14.0, including volume mesh division, setting material property parameters, boundary conditions, setting load of 1 200 N, acting time of 2 ms, and they were calculated in LS-DYNA software. RESULTS AND CONCLUSION: (1) The bone trabeculae in the region of interest showed uneven spatial distribution. (2) The bone trabeculae with small volume and small number first presented deformation fracture, and the plate shape and bone trabeculae with large volume finally demonstrated fracture collapse. (3) The change trend of von Mises stress was roughly the same as that of bone trabeculae fracture collapse. The fracture collapse process of bone trabeculae in the region of interest included vertical collapse and horizontal torsion, in which the degree and rate of horizontal torsion were lower than that of vertical collapse, making the size and rate of cross-section torsion angle less than that of coronal plane angle. (5) The increase and peak value of shear stress of failure unit were smaller than Von-mises stress. (6) These results indicate that fracture collapse of bone trabecula is a complex process, including deformation and angle of different planes.
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Aim To study the influence of Sodium fer-ulate ( SF) on bone metabolism in glucocorticoid–in-duced osteoporosis rats. Methods Thirty cases of fe-male Wistar Rats(3-month-old) were divided into con-trol group, model group and SF group ( low-dose group, middle-dose group, high-dose group ) by ran-domized block design. Double fluorochrome labeling with calcein was performed before necropsy. The left tibia was taken for bone histomorphometry. Results In static parameters, the proximal tibia cancellous bone trabecular thickness, trabecular quantity and area ratio were significantly reduced in model group compared with control group;while compared with model group, those were increased in middle and high-dose SF group. Trabecular separation degree was increased in model group compared with control group, while it was decreased in middle and high-dose SF group compared with model group. In dynamic parameters, the calcula-tion parameters of cancellous bone mark perimeter rate and the bone formation rate were increased in model group compared with control group, in middle and high-dose SF group the bone formation rate was in-creased compared with model group. In bone cells, os-teoclast number per mm, osteoblast number per mm, percent osteoblast surface perimeter and percent osteo-clast surface perimeter were increased in model group compared with control group. In growth-plate, the thickness of growth-plate was increased in model group compared with control group. In bone cells and growth-plate there was no statistical significance between treat-ment group and model group. Conclusion This study demonstrates that SF can increase bone mass and im-prove bone structure,which may be related to the im-provement of bone formation. SF is effective for GIOP in rats.
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0.05).[Conclusion]The values of three-dimensional parameters in old femoral neck fracture patient are different with that of normal persons in the loading region of the femoral head although there is no difference in BMD values between them.This may provide new evidence to predict osteoporotic femoral neck fracture.