Protective effects of sirtuin 3 on titanium particle-induced osteogenic inhibition by regulating the NLRP3 inflammasome via the GSK-3β/β-catenin signalling pathway

Periprosthetic osteolysis(PPO)remains the key factor in implant failure and subsequent revision surgery and is mainly triggered by wear particles.Previous studies have shown that inhibition of osteoblastic differentiation is the most widespread incident affecting the interface of trabecular and loosening prostheses.Additionally,the NLRP3 inflammasome is activated by prosthetic particles.Sirtuin3,an NAD+-dependent deacetylase of mitochondria,regulates the function of mitochondria in diverse activities.However,whether SIRT3 can mitigate wear debris-induced osteolysis by inhibiting the NLRP3 inflammasome and enhancing osteogenesis has not been previously reported.Therefore,we investigated the role of SIRT3 during the process of titanium(Ti)particle-induced osteolysis.We revealed that upregulated SIRT3 dramatically attenuated Ti particle-induced osteogenic inhibition through suppression of the NLRP3 inflammasome and improvement of osteogenesis in vivo and in vitro.Moreover,we found that SIRT3 interference in the process of Ti particle-induced osteolysis relied on the GSK-3β/β-catenin signalling pathway.Collectively,these findings indicated that SIRT3 may serve as a rational new treatment against debris-induced PPO by deacetylase-dependent inflammasome attenuation.

The effects of icariine concentration on osteoclasts bone resorption induced by titanium particles in vitro

In artificial joint replacement,osteoclast bone resorption induced by wear debris of the implant is a main reason for aseptic loosening.To extend the life of the prosthesis,detailed mechanisms of aseptic loosening and the ways to prevent it should be explored.The aim of this study was to investigate the in vitro effect of icariine on the bone resorption of osteoclasts induced by titanium particles.Macrophage colony stimulating factor(M-CSF)and receptor activator of NF-kB ligand(RANKL)were used to generate osteoclasts from RAW264.7 precursors.The proliferation of RAW264.7 precursors in the presence of different doses of icariine was evaluated by MTT assay.The cells were treated with titanium particles,titanium particles with icariine and culture medium only(control),respectively.At 48 h after treatment,the expression level of receptor activator of NF-kB(RANK)was detected by ELISA,and messenger RNA(mRNA)levels of tartrate-resistant acid phosphatase(TRAP),matrix metalloproteinase 9(MMP-9),carbonic anhydrase II(CAII)and Cathepsin K(CtsK)were determined by real-time polymerase chain reaction.Western blot was applied to analyze the expression levels of TRAP,RANK and CtsK.In addition,bone chips were cultured in the above conditions,and Toluidine blue staining was then employed to calculate the number and area of resorption pits in the bone chips.After treatment with icariine,expression level of RANK was significantly decreased in the RAW264.7 cell that induced by titanium particle and its cultural medium,mRNA and protein levels of TRAP,CAII,MMP-9 and CtsK were reduced as well.In addition,the numbers of bone resorption pits and areas on bone slices were both reduced by icariine challenging.Icariine could inhibit bone resorption of osteoclast induced by titanium particle,and it might be used as a promising drug for treating of aseptic loosening.

Formation of Rutile Nanoparticles from the Condensed Disperse Phase at a Surface of High-Temperature Particles

The photos, which are done by electron microscope, of the condensed disperse phase, surrounding high-temperature metal particles are presented. The dependence of concentration of condensed dispersive phase which surrounds a high-temperature metal particle upon the temperature of the particle was obtained. The dependence of concentration of electrons in condensed dispersive phase upon the temperature of the particle was studied. The dependence of an equilibrium charge of a metal particle surrounded with condensed disperse phase on the temperature of a particle in a positive and negative region is presented. The dependence of a charge of a metal particle on time at the fixed temperature is obtained.

EFFECT OF INHALED NANO-TiO_2 ON LUNG AND SERUM BIOCHEMICAL INDEXES OF MICE

The effect of inhaled nano-TiO2 on lung histology and serum biochemical indexes is evaluated in healthy and adult Kunming mice（eight in each group）after exposure to TiO2 aerosols（1 500 mg/m3）in a sealed chamber.Another eight mice are exposed to indoor air to be served as a control group.Lung tissue and blood are collected after euthanizing the animals.The results show that lactate dehydrogenase（LDH）activity increases in all experimental groups.Alanine aminotransferase（ALT）activity and blood urea nitrogen（BUN）levels are increased in the group exposed to TiO2 aerosols for 28 d,and creatinine（Cr）levels are increased in 14 d and 28 d samples（P0.05）.No obvious changes are observed in other serum indexes.Lungs of mice exposed to 28 d exposure show significant but moderate increase in pulmonary inflammation,and many TiO2 particles are found in the interstitium of pulmonary alveoli.

INVESTIGATION OF MULTIPHASE-REINFORCED Si_3N_4 COMPOSITE MATERIAL

By means of whisker reinforce and paricle dispersion, the routes of property improvement on Si3N4 ceramic material have been studied. The medhaniacl properties of Siw/Si3N4 and Siw/Si3N4TiC material was compared, which proved that multiphase reinforce had overlap effect. Microstructure of the rnaterial was investigated by means of SEM and the mechanisms of SiC. and TiCP reinforces had been disussed.

Effect of Ti_(p) Content on the Work Hardening and Softening Behavior of Mg-Zn-Ca Alloy

The Ti_(p)/ZX60 composites with different Ti_(p) contents were prepared by semi-solid stirring casting.After extrusion,the microstructure,work hardening and softening behavior of the Ti_(p)/ZX60 composites were analyzed compared with the ZX60(Mg-6Zn-0.2Ca)alloy.The results showed that the addition of Ti_(p) could not only promote the nucleation of dynamic recrystallized(DRXed)grains,but also be propitious to the refinement of DRXed grains.With increasing Ti_(p) content,the size of DRXed grains decreased accompanied with increasing volume fraction of DRXed grains.As the Ti_(p) content increased to 15 vol.%,the average size and volume fraction of DRXed grains reached to~0.32μm and 93.2%,respectively.Besides,both the strength and elongation were improved by the addition of Ti_(p).With increasing content of Ti_(p),a substantial increase in the strength was achieved with little change in the elongation.However,the elongation decreased sharply when the Ti_(p) content further increased to 15 vol.%.The addition of Ti_(p) led to an increase in the work hardening rate,which gradually increased with increasing Ti_(p) content.However,the softening rate did not demonstrate the same tendency with increasing Ti_(p) content.Unlike the conventional ceramic particles,the Ti_(p) can be deformed in coordination with the matrix alloy,which imparted a higher softening rate to the matrix alloy.Even though the softening rate improved as the Ti_(p) content increased from 5 to 10 vol.%,it dropped deeply as the Ti_(p) content increased to 15 vol.%owing to the fracture of Ti_(p) during extrusion.

Grinding behavior and surface appearance of(TiC_p+ TiB_w)/Ti-6Al-4V titanium matrix composites

（TiCp＋ TiBw）/Ti-6Al-4V titanium matrix composites（PTMCs） have broad application prospects in the aviation and nuclear field. However, it is a typical difficult-to-cut material due to high hardness of the reinforcements, high strength and low thermal conductivity of Ti-6Al-4V alloy matrix. Grinding experiments with vitrified CBN wheels were conducted to analyze comparatively the grinding performance of PTMCs and Ti-6Al-4V alloy. Grinding force and force ratios, specific grinding energy, grinding temperature, surface roughness, ground surface appearance were discussed. The results show that the normal grinding force and the force ratios of PTMCs are much larger than that of Ti-6Al-4V alloy. Low depth of cut and high workpiece speed are generally beneficial to achieve the precision ground surface for PTMCs. The hard reinforcements of PTMCs are mainly removed in the ductile mode during grinding. However, the removal phenomenon of the reinforcements due to brittle fracture still exists, which contributes to the lower specific grinding energy and grinding temperature of PTMCs than Ti-6Al-4V alloy.

Effects of different concentrations of TiAl6V4 particles on MC3T3-E1 cells and bone in rats

Three-dimensional(3D)-printed porous Ti6Al4V implants have good mechanical properties and excellent biocompatibility.As such,these implants are widely used in orthopedics.Particles adhere between the sintered and nonsintered interfaces of the porous samples during 3D printing.These excess particles can be cleaned by blowing the particles and via ultrasound,but the excess internal particles of complex structural parts are difficult to remove.During long-term cyclic loading,stress and strain can cause residual Ti6Al4V particles in the pores of the implant to shed.These detached Ti6Al4V particles are in extensive contact with osteoblasts and scattered around the implant.In this study,we examined the effects of different concentrations of Ti6Al4V particles on osteoblasts and bones.MC3T3-E1 cells were used to evaluate the effects of different concentrations of Ti6Al4V particles on cells after 72 h on the basis of the expression levels of genes,involving osteopontin,alkaline phosphatase,bone morphogenetic protein-2 and runt-related transcription factor-2.Microtubule-associated protein 1 light chain 3 was used to detect the autophagy of MC3T3-E1 with different concentrations of Ti6Al4V particles.The distal femoral defects of rats were examined to examine bone growth with different concentrations of Ti6Al4V particles.All rats were accepted by micro-CT and biochemical analyses after 12 weeks.The results indicated that 10 and 100μg/ml of Ti6Al4V particles may improve osteogenic differentiation.Micro-CT revealed that low concentrations of Ti6Al4V particles may improve the osteogenesis of the rats.However,the(cortical and trabecular)BMD of middle and high dose groups was no significant change compared with control group.In conclusion,low-dose residual particles do not inhibit osteoblast differentiation and do not decrease the bone mineral density of rats.