The present study was aimed at the optimal solution of the main muscular force distribution in the lower extremity during standing balance of human. The movement musculoskeletal system of lower extremity was simplified to a physical model with 3 joints and 9 muscles. Then on the basis of this model, an optimum mathematical model was built up to solve the problem of redundant muscle forces. Particle swarm optimization (PSO) algorithm is used to calculate the single objective and multi-objective problem respectively. The numerical results indicated that the multi-objective optimization could be more reasonable to obtain the distribution and variation of the 9 muscular forces. Finally, the coordination of each muscle group during maintaining standing balance under the passive movement was qualitatively analyzed using the simulation results obtained.
ObjectiveTo explore the effect of expression of miRNA-21 on bone marrow mesenchymal stem cells (BMSCs).MethodsIn this study, flow cytometry was used to identify the surface-associated antigens of BMSCs. The 10 μmol/L 5-azacytidine was used to induce BMSCs to differentiate to cardiomyocyte-like cells. Immunofluorescence was used to detect the expression of troponin I (cTnI). The samples were assigned to 3 groups: a blank group, a miRNA-21 mimic group, and a negative control (NC) group. The proliferation of BMSCs was detected by methyl thiazolylte-trazolium (MTT), the apoptosis of BMSCs was analyzed by flow cytometry. Western-blotting was used to identify the expression of cTnI and myod in the BMSCs.ResultsThe proliferation of BMSCs was increased, because of the over expression of miRNA-21. But the apoptotic rate of the BMSCs was slower in the miRNA-21 group, on account of the expression of miRNA-21 was higher than that in the NC group and the CK group. The expression of cTnI in the miRNA-21 group was higher than that in the NC group or the CK group.ConclusionThe results suggest that the up-regulation of miRNA-21 enhances proliferation of BMSCs, reduces the apoptosis of BMSCs. miRNA-21 promotes the differentiation of BMSCs, which may pave the way for the treatment directed toward restoring miRNA-21 function for myocardial ischemia.
Objective To explore the effect of short-term low-frequency electrical stimulation (SLES) during operation on nerve regeneration in delayed peripheral nerve injury with long gap. Methods Thirty female adult Sprague Dawley rats, weighing 160-180 g, were used to prepare 13-mm defect model by trimming the nerve stumps. Then all rats were randomly divided into 2 groups, 15 rats in each group. After nerve defect was bridged by the contralateral normal sciatic nerve, SLES was applied in the experimental group, but was not in the control group. The spinal cords and dorsal root ganglions (DRGs) were harvested to carry out immunofluorescence histochemistry double staining for growth-associated proteins 43 (GAP-43) and brain-derived neurotrophic factor (BDNF) at 1, 2, and 7 days after repair. Fluorogold (FG) retrograde tracing was performed at 3 months after repair. The mid-portion regenerated segments were harvested to perform Meyer’s trichrome staining, immunofluorescence double staining for neurofilament (NF) and soluble protein 100 (S-100) on the transversely or longitudinal sections at 3 months after repair. The segment of the distal sciatic nerve trunk was harvested for electron microscopy and morphometric analyses to measure the diameter of the myelinated axons, thickness of myelin sheaths, the G ratio, and the density of the myelinated nerve fibers. The gastrocnemius muscles of the operated sides were harvested to measure the relative wet weight ratios. Karnovsky-Root cholinesterase staining of the motor endplate was carried out. Results In the experimental group, the expressions of GAP-43 and BDNF were higher than those in the control group at 1 and 2 days after repair. The number of labeled neurons in the anterior horn of gray matter in the spinal cord and DRGs at the operated side from the experimental group was more than that from the control group. Meyer’s trichrome staining, immunofluorescence double staining, and the electron microscopy observation showed that the regenerated nerves were observed to develop better in the experimental group than the control group. The relative wet weight ratio of experimental group was significantly higher than that of the control group (t=4.633,P=0.000). The size and the shape of the motor endplates in the experimental group were better than those in the control group. Conclusion SLES can promote the regeneration ability of the short-term (1 month) delayed nerve injury with long gap to a certain extent.