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Objective To investigate the effects of cyclic stretch on migration of MC3T3-E1 cells and its related mechanism. Methods The strain loading system was used to stretch MC3T3-E1 cells cultured in vitro with 15% amplitude, to simulate the mechanical condition in vivo. The wound healing assay was used to detect the migration of MC3T3-E1 cells. Western blotting was used to test Runx2 expression. RNA interfering was used to decrease Runx2 expression. Results Cyclic mechanical stretch with 15% amplitude, 1.25 Hz frequency and lasting for 24 hours could promote the migration of MC3T3-E1 cells and increase the expression level of Runx2. Runx2 interference inhibited the migration of MC3T3-E1 cells in static culture condition. Interference with Runx2 expression in MC3T3-E1 cells could partially reduce the positive effect of cyclic mechanical stretch on cell migration. Conclusions Cyclic stretch can promote the migration of MC3T3-E1 cells, and Runx2 may play an important role in this process. This study provides experimental basis for finding innovative clinical treatment method to promote fracture healing.
ABSTRACT
Objective@#ICMM occupational health risk assessment model was be used to evaluate the risk of a lead-acid battery enterprise. @*Methods@#In November 2016, a lead-acid battery company in Jiangsu Province was selected as the research object. Based on the occupational health survey data and occupational hazard assessment reports, the ICMM risk assessment model was used to conduct occupational health risks in eight key positions of a lead-acid battery enterprise. The risk assessment results was verified by actual test results. @*Results@#In the quantitative assessment model, the occupational health risk assessment results for the castings and welding positions exposed to lead smoke, and the occupational health risk assessment results for the grinding and dividing positions exposed to lead dust existed unacceptable risks. The occupational health risk assessment results for the ball-milled and plated positions exposed to lead dust existed tolerable risks. The occupational health risk assessment results for the lead-plated and soldered positions exposed to sulphuric acid pastes and acids existed potential risks. In qualitative evaluation matrix method, the occupational health risk assessment results for the castings and welding positions exposed to lead smoke, and the occupational health risk assessment results for the grinding and dividing positions exposed to lead dust existed high risks, the occupational health risk assessment results for other four key positions were considered to be with low risks. @*Conclusion@#The key control points for lead smoke in this enterprise were castings and welding positions; The key control points for lead dust were the grinding and separating brush positions. The quantitative assessment model and the qualitative assessment matrix method in the ICMM model were consistent with the actual test results in the eight health risk assessments of occupational hazards in key positions. Therefore, the method could be applied to the assessment of occupational health risks of the lead-acid battery enterprise. According to the results of the assessment, improvements could be made to high-risk positions and the concentration of occupational hazards in high-risk posts could be reduced to better protect the health of workers.
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Objective To explore the mechanism of cell apoptosis of immortalized human keratinocytes (HaCaT cells) and protein expression related to this process after long term exposure to sodium arsenite (NaAsO2,1.0 μmol/L).Methods Malignant transformation model was set up through long-term exposure of HaCaT cells to 1.0 μmol/L NaAsO2.Cell passage for 0,1,7,14,21,28 and 35 generations in the process of malignant transformation were collected for measurement of cell apoptosis rate by flow cytometry,and apoptosis related proteins by Western blotting,including activation of cysteine protease 3,8 (cleaved-caspase-3,8),C/EBP homologous protein (CHOP),B-cell leukemia/lymphoma 2 (Bcl-2),and Bcl-2 associated X protein (Bax).Results Along with the arsenite treatment,the apoptosis levels were significantly decreased (F =26.770,all P ＜ 0.05),the apoptosis levels (0.307 ± 0.049,0.213 ± 0.055,0.163 ± 0.057,0.147 ± 0.035,0.053 ± 0.012) of the 7th,14th,21st,28th and 35thgenerations of cells after arsenite treatment were lower than that of control group of the 0th generation (0.393 ±0.021,all P ＜ 0.05).Compared between generations,there were statistical differences of the protein expression levels of cleaved-caspase-3,Chop,Bax and Bcl-2 in arsenite group (cleaved-caspase-3:1.000 ± 0.000,1.030 ± 0.027,1.104 ± 0.069,1.016 ± 0.087,0.838 ± 0.075,0.753 ± 0.082,0.677 ± 0.073;Chop:1.000 ± 0.000,1.059 ± 0.018,0.934 ± 0.095,0.976 ± 0.216,0.793 ± 0.136,0.651 ± 0.042,0.564 ± 0.056;Bax:1.000 ± 0.000,1.069 ± 0.037,1.028 ± 0.042,0.954 ± 0.118,0.641 ± 0.135,0.531 ± 0.132,0.429 ± 0.085;Bcl-2:1.000 ± 0.000,1.072 ± 0.023,1.249 ± 0.134,1.334 ± 0.143,1.633 ± 0.221,1.507 ± 0.152,1.461 ± 0.145,F =7.730,7.355,27.802,12.438,all P ＜ 0.05),compared with control group of the 0th generation (1.000 ± 0.000) and the same generation control group (1.000 ± 0.000),after the 21st generation,the differences were statistically significant (all P ＜ 0.05),while there was no difference of the protein expression levels of cleaved-caspase-8 (F =0.832,P ＞ 0.05).Conclusion In the process of malignant transformation,the apoptosis levels of HaCaT cells are inhibited after long term sodium arsenite exposure through mitochondria and endoplasmic reticulum (ER) stress signaling pathways.