SIRT1 Inhibits High Shear Stress-Induced Apoptosis in Rat Cortical Neurons.

INTRODUCTION: Sirtuin1 (SIRT1), one of NAD+-dependent protein deacetylases, is proved to be neuroprotective in aging diseases, but its effect on neuronal apoptosis has not been clarified. To investigate the role of SIRT1 in inhibiting neuronal apoptosis, SIRT1 was interfered or overexpressed in cortical neurons. METHODS: We exerted overloading laminar shear stress with 10 dyn/cm2 for 4, 8, and 12 h on neurons to cause cortical neuronal apoptosis, and the apoptosis percentage was tested by TUNEL assay. The adenovirus plasmids containing SIRT1 RNA interference or SIRT1 wild type gene were transfected into neurons before shear stress loading. SIRT1 mRNA and protein level were tested by Real-time PCR, immunofluorescence and western blots assay. RESULTS: SIRT1 was primarily expressed in nucleus of cortical neurons, and its mRNA level was significantly increased after 4 h stimulation. SIRT1 RNAi cortical neurons had higher TUNEL positive cells, while SIRT1 overexpression significantly decreased the percentage of died cells induced by shear stress compared to control group. CONCLUSIONS: SIRT1 plays a neuroprotective role in shear stress induced apoptosis and could be as potential pharmacological targets against neuronal degeneration in future.

Spontaneous cellular vibratory motions of osteocytes are regulated by ATP and spectrin network.

Vibration at high frequency has been demonstrated to be anabolic for bone and embedded osteocytes. The response of osteocytes to vibration is frequency-dependent, but the mechanism remains unclear. Our previous computational study using an osteocyte finite element model has predicted a resonance effect involving in the frequency-dependent response of osteocytes to vibration. However, the cellular spontaneous vibratory motion of osteocytes has not been confirmed. In the present study, the cellular vibratory motions (CVM) of osteocytes were recorded by a custom-built digital holographic microscopy and quantitatively analyzed. The roles of ATP and spectrin network in the CVM of osteocytes were studied. Results showed the MLO-Y4 osteocytes displayed dynamic vibratory motions with an amplitude of ~80 nm, which is relied both on the ATP content and spectrin network. Spectrum analysis showed several frequency peaks in CVM of MLO-Y4 osteocytes at 30 Hz, 39 Hz, 83 Hz and 89 Hz. These peak frequencies are close to the commonly used effective frequencies in animal training and in-vitro cell experiments, and show a correlation with the computational predictions of the osteocyte finite element model. These results implicate that osteocytes are dynamic and the cellular dynamic motion is involved in the cellular mechanotransduction of vibration.

Percutaneous Sacroiliac Screw Placement: A Prospective Randomized Comparison of Robot-assisted Navigation Procedures with a Conventional Technique.

BACKGROUND: Sacroiliac (SI) screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot™ is an orthopedic surgery robot which can be used for SI screw fixation. This study aimed to evaluate the accuracy of robot-assisted placement of SI screws compared with a freehand technique. METHODS: Thirty patients requiring posterior pelvic ring stabilization were randomized to receive freehand or robot-assisted SI screw fixation, between January 2016 and June 2016 at Beijing Jishuitan Hospital. Forty-five screws were placed at levels S1 and S2. In both methods, the primary end point screw position was assessed and classified using postoperative computed tomography. Fisher's exact probability test was used to analyze the screws' positions. Secondary end points, such as duration of trajectory planning, surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction, were also assessed. RESULTS: Twenty-three screws were placed in the robot-assisted group and 22 screws in the freehand group; no postoperative complications or revisions were reported. The excellent and good rate of screw placement was 100% in the robot-assisted group and 95% in the freehand group. The P value (0.009) showed the same superiority in screw distribution. The fluoroscopy time after pelvic reduction in the robot-assisted group was significantly shorter than that in the freehand group (median [Q1, Q3]: 6.0 [6.0, 9.0] s vs. median [Q1, Q3]: 36.0 [21.5, 48.0] s; χ2 = 13.590, respectively, P < 0.001); no difference in operation time after reduction of the pelvis was noted (χ2 = 1.990, P = 0.158). Time for guide wire insertion was significantly shorter for the robot-assisted group than that for the freehand group (median [Q1, Q3]: 2.0 [2.0, 2.7] min vs. median [Q1, Q3]: 19.0 [15.5, 45.0] min; χ2 = 20.952, respectively, P < 0.001). The number of guide wire attempts in the robot-assisted group was significantly less than that in the freehand group (median [Q1, Q3]: 1.0 [1.0,1.0] time vs. median [Q1, Q3]: 7.0 [1.0, 9.0] times; χ2 = 15.771, respectively, P < 0.001). The instrumented SI levels did not differ between both groups (from S1 to S2, χ2 = 4.760, P = 0.093). CONCLUSIONS: Accuracy of the robot-assisted technique was superior to that of the freehand technique. Robot-assisted navigation is safe for unstable posterior pelvic ring stabilization, especially in S1, but also in S2. SI screw insertion with robot-assisted navigation is clinically feasible.

Biomechanical analysis of suture locations of the distal plantar fascia in partial foot.

PURPOSE: The aim of this study was to evaluate the rationality of the suture locations of distal plantar fascia (DPF) after foot amputation to avoid the risk factors of re-amputation or plantar fasciitis. METHODS: The tensile strain of plantar fascia (PF) in the different regions was measured by uni-axial tensile experiment. A three-dimensional (3D) finite element model was also developed to simulate tensile behaviour of PF in weight bearing conditions. The model includes 12 bones, ligaments, PF, cartilage and soft tissues. Four suture location models for the DPF were considered: the fourth and fifth DPF were sutured on the third metatarsal, the cuboid, and both the third metatarsal and the cuboid, and one un-sutured model. RESULTS: The peak tensile strain of the first, second and third PF was 0.134, 0.128 and 0.138 based on the mechanical test, respectively. The fourth and fifth DPF sutured at the cuboid and the third metatarsal could offer more favourable outcomes. The peak strain of 4.859 × 10(-2), 2.347 × 10(-2) and 1.364 × 10(-2) in the first, second and third PF showed the least outcomes in stance phase. Also, peak strain and stress of the residual PF reduced to 4.859 × 10(-2) and 1.834 MPa, respectively. The stress region was redistributed on the mid-shaft of the first and third PF and the peak stress of medial cuneiform bone evidently decreased. CONCLUSIONS: The fourth and fifth DPF suture at the third metatarsal and cuboid was appropriate for the partial foot. The findings are expected to suggest optimal surgical plan of the DPF suture and guide further therapeutic planning of partial foot patients.

[The Biomechanics Influence of unilateral laminectomy and discectomy surgery on the adjacent different grades of Disc Degeneration].

OBJECTIVES: To study the stress distribution of the adjacent different grades of disc degeneration underwenting unilateral laminectomy and discectomy surgery using non-linear finite element analysis. METHODS: Based on the lumbar CT scans, the finite element model (FEM) of lumbar spinal segment (L3-L5) was established. According to L3-L4 intervertebral disc degeneration, different grades of disc degeneration (healthy, mild, moderate and severe) models were established and unilateral laminectomy and discectomy surgery were also established. Physiological action such as flexion, extension, lateral bending and lateral rotation was simulated and the von Mises stress in the nucleus pulposus and annulus fibrosus matrix of L3-L4 disc was investigated. RESULTS: After unilateral laminectomy and discectomy surgery, the extremum value of von Mises stress of nucleus pulposus and annulus fibrosus matrix was maximum during extension and minimus left bending in the healthy intervertebral disc. Compared with healthy disc, the increment of extremum value was found during left bending in the mildly degenerated disc. When the value decreased in the moderately degenerated disc, but still higher than that in the healthy disc. When the adjacent disc is severely degenerated, the extremum value of nucleus pulposus decreased, in addition to axial rotation, and even lower than that of healthy disc. The value of annulus matrix decreased and still higher than that of healthy disc, especially during left bending. CONCLUSIONS: After unilateral laminectomy and discectomy surgery, avoiding lateral bending will reduce the abnormal stress in the degenerated disc and decreased the risk of accelerating disc degeneration.

Potential protection of green tea polyphenols against 1800 MHz electromagnetic radiation-induced injury on rat cortical neurons.

Radiofrequency electromagnetic fields (EMF) are harmful to public health, but the certain anti-irradiation mechanism is not clear yet. The present study was performed to investigate the possible protective effects of green tea polyphenols against electromagnetic radiation-induced injury in the cultured rat cortical neurons. In this study, green tea polyphenols were used in the cultured cortical neurons exposed to 1800 MHz EMFs by the mobile phone. We found that the mobile phone irradiation for 24 h induced marked neuronal cell death in the MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide) and TUNEL (TdT mediated biotin-dUTP nicked-end labeling) assay, and protective effects of green tea polyphenols on the injured cortical neurons were demonstrated by testing the content of Bcl-2 Assaciated X protein (Bax) in the immunoprecipitation assay and Western blot assay. In our study results, the mobile phone irradiation-induced increases in the content of active Bax were inhibited significantly by green tea polyphenols, while the contents of total Bax had no marked changes after the treatment of green tea polyphenols. Our results suggested a neuroprotective effect of green tea polyphenols against the mobile phone irradiation-induced injury on the cultured rat cortical neurons.

TiO2 nanoparticles translocation and potential toxicological effect in rats after intraarticular injection.

Recently, nanomaterials coating gained much concern in orthopedic implants such as bone, cartilage, joint, etc. The wear particles would generate from coating in living organism due to corrosion. In this study, we demonstrated that the intraarticular injected anatase TiO2 nanoparticles had a potential toxicological effect on major organs and knee joints of rats. The histopathological changes of heart, lung and liver indicated the dissemination of intraarticular TiO2 nanoparticles from joint cavity to system. In the knee joint, the aggregated TiO2 nanoparticles deposited and resulted in the synovium hypotrophy and lymphocytes and plasma cells infiltration, but had no effects on cartilage. In the TiO2-exposed synovium, the oxidative damage was induced because the glutathione peroxidase (GSH-Px), reduced glutathione (GSH), oxidized glutathione (GSSG), and superoxide dismutase (SOD) levels were highly regulated to counteract over-produced free radicals, i.e. hydrogen peroxide (H2O2). Further, the lipid peroxidation was detected in the synovium though the expression of proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) and interleukin (IL-1beta) was not much interfered. This research suggested that the amounts of nanocoating in the surface of implants should be controlled and standardized.

Biomechanical evaluation of Le Fort I maxillary fracture plating techniques.

PURPOSE: This study used a biomechanical model to examine fundamental questions about rigid plate fixation treatment for maxillary Le Fort I fractures. Specifically, we sought to elucidate the principal strain patterns generated in miniplates and bite force transducers secondary to all masticatory forces, as well as the amount of permanent deformations incurred due to these loading forces. MATERIALS AND METHODS: Forty polyurethane synthetic maxillary and mandibular replicas were used to simulate the mandible and maxilla. Ten replicas were controls (group A). The other 30 were divided into 3 groups (10 each), according to the fixation techniques of 3, 2, and 1 miniplates each side (groups B-D), that were osteotomized in the Le Fort I fracture line on the maxilla. Different forces of masseter medial pterygoid, temporalis, and lateral pterygoid muscles were loaded onto the replicas to simulate different functional conditions (anterior incisor, premolar, and molar clenching). Rosette strain gauges were attached at predefined points on the plates and the bite force transducer to compare the stability and bite force of the different fixation methods for maxillary Le Fort I fractures. RESULTS: Statistically significant differences were found for the deformation of the plates among fixation techniques. The order of stability for each technique was: group B greater than group C greater than group D. In regard to bite force, no difference was found between those found with group A and group B (P > .05), whereas the bite forces of groups C and D were less than those of group A (P < .05). CONCLUSIONS: The fixation of 3 miniplates on each side provides sufficient stability and restores the bite force to the level of the intact maxilla. "The ideal fixation" with 2 miniplates on each side restores 90% of the bite force, and there were more deformations of the miniplates with the "ideal fixation" compared to those found with group B. Group D fixation produced the worst effects for the treatment of maxillary Le Fort I fractures with a weak bite force and insufficient stability.

[Experimental study on the proliferation and function of osteoblast cell induced by pBLAST49-mVEGF gene transfection].

OBJECTIVE: To assess the effects of extra VEGF gene expression on the proliferation of osteoblast cell. METHODS: The extra VEGF gene was induced into osteoblast cell. Then the expression of extra VEGF gene was detected, and its effects on the cell proliferation curve, cell cycle, on the synthesis of type I collagen and on the secretion of osteocalcium of osteoblast cell were investigated. RESULTS: At the first two days of culture, the cell number of pBLAST49-mVEGF gene transfer group was larger than that of the control group, yet no statistically significant difference was seen between the two groups (P > 0.05); however, significant difference was observed from the 3rd day of culture (P < 0.05). The (G2/M+S)% of the 1-5 generation osteoblast cell in pBLAST49-mVEGF gene transfer group was higher than that of the control group, there was significant difference between them (P < 0.05). The concentration of osteocalcium and expression of type I collagen of the 1-5 generation osteoblast cell in pBLAST49-mVEGF gene transfer group were significantly higher than those of the control group (P < 0.05). CONCLUSION: pBLAST49-mVEGF gene transfer can improve the proliferation and function of osteoblast cell.

Tellimagrandin I enhances gap junctional communication and attenuates the tumor phenotype of human cervical carcinoma HeLa cells in vitro.

Tellimagrandin I and chebulinic acid, two hydrolysable tannins, have been shown to exert anti-tumor properties. Dysfunctional gap junctional communication (GJIC) has been recognized as being involved in carcinogenesis. The human cervical carcinoma HeLa cells have been reported to be deficient in functional GJIC. In present study, we investigated whether tellimagrandin I and chebulinic acid might restore functional GJIC in HeLa cells. Both compounds could inhibit the growth of HeLa cells. Either Lucifer yellow transfer assay or calcein transfer assay demonstrated that tellimagrandin I improved GJIC in HeLa cells while chebulinic acid showed no effect on GJIC. The GJIC enhancement by tellimagrandin I occurred along with an increase of Cx43 gene expression at mRNA and protein levels. Exposure to tellimagrandin I also led to inhibition of proliferation and anchorage-independent growth of HeLa cells. In addition, tellimagrandin I decreased the percentage of cells in the G0/G1 and G2/M phases coinciding with an increase in the percentage of cells in the S phase. The accumulation of cells in S phase was coupled with a decreased expression of cyclin A that was critical to the progression of S phase. These results suggested that restoring GJIC might be one explanation for tellimagrandin I antitumor effects, whereas chebulinic acid exerted antitumor action through other pathways.

[Expression of osteoclast differentiation factor and intercellular adhesion molecule-1 of bone marrow mesenchymal stem cells enhanced with osteogenic differentiation].

OBJECTIVE: To investgate whether the expression of osteoclast differentiation factor (ODF), intercellular adhesion molecule-1 (ICAM-1) depended on the stage of osteoblastic differentiation from rat bone marrow mesenchymal stem cells (BMSC). METHODS: BMSC (4 passage) were selected for osteogenic differentiation by treated with osteogenic supplements (OS). Cells were harvested by day 0, 3, 6, 9, 12, 18 respectively after osteogenic inducement. In each experiment, control and OS-treated cells were processed in parallel. ODF and ICAM-1 mRNA were analyzed by semiquantitave RT-PCR assay. RESULTS: Expression of ODF was enhanced with osteogenic differentiation guadully. whereas, expression of ICAM-1 was activated at OS-treated day 6, then keeping at a stable level. CONCLUSION: This study indicated that BMSC undergoing osteogenic inducement was an ideal model for studying the differentiation and maturation of osteoblasts. During the early stage of differentiation along osteoblasts from stem cells to osteocytes, BMSC or osteoprogenitor react somewhat differently from osteoblasts, suggesting the ability of osteoblasts to regulating differentiation and maturation of osteoclasts have been improved with osteogenic culture.