Entity

Time filter

Source Type


Liu M.,Nanjing Normal University | Xu L.,Nanjing Normal University | Ma X.,Nanjing Normal University | Xu J.,University of Western Australia | And 8 more authors.
American Journal of Pathology | Year: 2015

Melanoma antigen family D1 (MAGED1), an important adaptor protein, has been shown to ubiquitously express and play critical roles in many aspects of cellular events and physiological functions. However, its role in bone remodeling remains unknown. We, therefore, analyzed the bone phenotype of Maged1-deficient mice. Maged1-deficient mice displayed a significant osteoporotic phenotype with a marked decrease in bone density and deterioration of trabecular architecture. Histomorphometric analysis demonstrated an increased mineral apposition rate as well as increased osteoclast number and surface in Maged1 knockout mice. At the cellular level, Maged1-deficient osteoblasts exhibited an increased proliferation rate and accelerated differentiation. MAGED1 deficiency also caused a promotion in osteoclastogenesis, and that was attributed to the cell autonomous acceleration of differentiation in osteoclasts and an increased receptor activator of NF-κB ligand/osteoprotegerin ratio, a major index of osteoclastogenesis, in osteoblasts. Thus, we identified MAGED1 as a novel regulator of osteoblastogenesis, osteoclastogenesis, and bone remodeling in a mouse model. © 2015 American Society for Investigative Pathology. Source


Niu W.X.,Tongji University | Niu W.X.,Hong Kong Polytechnic University | Niu W.X.,Beihang University | Tang T.T.,Shanghai Key Laboratory of Orthopaedic Implants | And 3 more authors.
Science China Life Sciences | Year: 2014

A good knowledge of midfoot biomechanics is important in understanding the biomechanics of the entire foot, but it has never been investigated thoroughly in the literature. This study carried out in vitro experiments and finite element analysis to investigate the midfoot biomechanics. A foot-ankle finite element model simulating the mid-stance phase of the normal gait was developed and the model validated in in vitro experimental tests. Experiments used seven in vitro samples of fresh human cadavers. The simulation found that the first principal stress peaks of all midfoot bones occurred at the navicular bone and that the tensile force of the spring ligament was greater than that of any other ligament. The experiments showed that the longitudinal strain acting on the medial cuneiform bone was −26.2±10.8 μ-strain, and the navicular strain was −240.0±169.1 μ-strain along the longitudinal direction and 65.1±25.8 μ-strain along the transverse direction. The anatomical position and the spring ligament both result in higher shear stress in the navicular bone. The load from the ankle joint to five branches of the forefoot is redistributed among the cuneiforms and cuboid bones. Further studies on the mechanism of loading redistribution will be helpful in understanding the biomechanics of the entire foot. © 2014, The Author(s). Source


Niu W.,Tongji University | Niu W.,Hong Kong Polytechnic University | Niu W.,Shanghai Key Laboratory of Orthopaedic Implants | Feng T.,Tongji University | And 2 more authors.
BioMed Research International | Year: 2014

Objectives. (1) To systematically review peak vertical ground reaction force (PvGRF) during two-leg drop landing from specific drop height (DH), (2) to construct a mathematical model describing correlations between PvGRF and DH, and (3) to analyze the effects of some factors on the pooled PvGRF regardless of DH. Methods. A computerized bibliographical search was conducted to extract PvGRF data on a single foot when participants landed with both feet from various DHs. An innovative mathematical model was constructed to analyze effects of gender, landing type, shoes, ankle stabilizers, surface stiffness and sample frequency on PvGRF based on the pooled data. Results. Pooled PvGRF and DH data of 26 articles showed that the square root function fits their relationship well. An experimental validation was also done on the regression equation for the medicum frequency. The PvGRF was not significantly affected by surface stiffness, but was significantly higher in men than women, the platform than suspended landing, the barefoot than shod condition, and ankle stabilizer than control condition, and higher than lower frequencies. Conclusions. The PvGRF and root DH showed a linear relationship. The mathematical modeling method with systematic review is helpful to analyze the influence factors during landing movement without considering DH. Corrigendum to Corrigendum to "Peak Vertical Ground Reaction Force during Two-Leg Landing: A Systematic Review and Mathematical Modeling" dx.doi.org/10.1155/2015/941923 © 2014 Wenxin Niu et al. Source


Niu W.X.,Tongji University | Niu W.X.,Hong Kong Polytechnic University | Niu W.X.,Shanghai Key Laboratory of Orthopaedic Implants | Wang L.J.,Tongji University | And 5 more authors.
Applied Bionics and Biomechanics | Year: 2013

Finite element analysis (FEA) is a powerful tool in biomechanics. The mechanical properties of biological tissue used in FEA modeling are mainly from experimental data, which vary greatly and are sometimes uncertain. The purpose of this study was to research how Young's modulus affects the computations of a foot-ankle FEA model. A computer simulation and an in-vitro experiment were carried out to investigate the effects of incremental Young's modulus of bone on the stress and strain outcomes in the computational simulation. A precise 3-dimensional finite element model was constructed based on an in-vitro specimen of human foot and ankle. Young's moduli were assigned as four levels of 7.3, 14.6, 21.9 and 29.2 GPa respectively. The proximal tibia and fibula were completely limited to six degrees of freedom, and the ankle was loaded to inversion 10° and 20° through the calcaneus. Six cadaveric foot-ankle specimens were loaded as same as the finite element model, and strain was measured at two positions of the distal fibula. The bone stress was less affected by assignment of Young's modulus. With increasing of Young's modulus, the bone strain decreased linearly. Young's modulus of 29.2 GPa was advisable to get the satisfactory surface strain results. In the future study, more ideal model should be constructed to represent the nonlinearity, anisotropy and inhomogeneity, as the same time to provide reasonable outputs of the interested parameters. © 2013-IOS Press and the authors. All rights reserved. Source


Sun W.,Shanghai JiaoTong University | Sun W.,Shanghai Key Laboratory of Orthopaedic Implants | Sun W.,Xuzhou Medical College | Zhang K.,Shanghai JiaoTong University | And 18 more authors.
PLoS ONE | Year: 2014

Objective: The effect of Sox9 on the differentiation of bone marrow mesenchymal stem cells (BMSCs) to nucleus pulposus (NP)-like (chondrocyte-like) cells in vitro has been demonstrated. The objective of this study is to investigate the efficacy and feasibility of Sox9-transduced BMSCs to repair the degenerated intervertebral disc in a rabbit model. Materials and Methods: Fifty skeletally mature New Zealand white rabbits were used. In the treatment groups, NP tissue was aspirated from the L2-L3, L3-L4, and L4-L5 discs in accordance with a previously validated rabbit model of intervertebral disc degeneration and then treated with thermogelling chitosan (C/Gp), GFP-transduced autologous BMSCs with C/Gp or Sox9-transduced autologous BMSCs with C/Gp. The role of Sox9 in the chondrogenic differentiation of BMSCs embedded in C/Gp gels in vitro and the repair effect of Sox9-transduced BMSCs on degenerated discs were evaluated by real-time PCR, conventional and quantitative MRI, macroscopic appearance, histology and immunohistochemistry. Results: Sox9 could induce the chondrogenic differentiation of BMSCs in C/Gp gels and BMSCs could survive in vivo for at least 12 weeks. A higher T2-weighted signal intensity and T2 value, better preserved NP structure and greater amount of extracellular matrix were observed in discs treated with Sox9-transduced BMSCs compared with those without transduction. Conclusion: Sox9 gene transfer could significantly enhance the repair effect of BMSCs on the degenerated discs. © 2014 Sun et al. Source

Discover hidden collaborations