ABSTRACT
Coal miners are a high-risk occupational group of work-related musculoskeletal disorders(WMSDs). This disease not only causes a reduction in the quality of life of workers, loss work ability, and decline in work efficiency, but also becomes an important factor leading to increase social medical burden. At present, most of the evaluation of WMSDs of coal miners at home and abroad adopts the international general scale. Chinese scholars have developed a WMSDs questionnaire that meets the occupational characteristics of Chinese population based on the international general scale—the Chinese Musculoskeletal Disorders Questionnaire. The questionnaire has good reliability and validity, and is a reliable and effective tool for evaluating WMSDs. The prevalence of WMSDs in coal miners is relatively high. The occupational factors that affect WMSDs in coal miners are mainly physical load, postural load, mental load, work organization, and work environment. The individual factors are mainly age, working experience, and education level. It′s recommended to prevent and control the occurrence of coal miners′ WMSDs through multi-level intervention measures such as strengthening education, changing the working posture, and improving the working conditions of coal miners, and rationally arranging labor organizations.
ABSTRACT
Objective:Astragalus polysaccharide (APS) was used in combination with ionizing radiation (IR) to investigate the mechanism of APS on the radiosensitivity of human nasopharyngeal narcinoma CNE-1 cells and the epithelial-mesenchymal transition (EMT). Method:Cell counting kit-8 (CCK-8) was used to detect the cytotoxicity of different concentrations of APS (0，6.25，12.5，25，50，100，200 g·L-1) on CNE-1 cells. Colony formation assay was used to calculate the survival fraction (survival fraction, SF) of CNE-1 cells treated with 12.5 g·L-1 APS combined with different radiation doses (0，2，4，6 Gy). The linear quadratic equation mathematical model (LQ) was used to draw the radiosensitivity curve according to SF value. Cell scratch and transwell chamber test were used to detect the migration and invasion ability of cells in each group. The apoptosis of cells in each group was detected by flow cytometry, Western blot was used to detect the expressions of EMT markers, apoptosis markers and protein kinase B/extracellular regulated protein kinases (Akt/ERK) pathway proteins in each group. Result:The results of colony formation assay and radiosensitivity curve showed that the combination of non-toxic dose of 12.5 g·L-1 APS and radiation dose of 4 Gy could significantly increase the radiosensitivity of CNE-1 cells. Compared with blank group and IR group, APS combined with IR could significantly inhibit the migration and invasion of CNE-1 cells (P<0.05), and increase the rate of apoptosis (P<0.05). In addition, compared with the blank group and the IR group, APS combined with IR could significantly down-regulate the expressions of N-cadherin, p-Akt and p-ERK, and significantly up-regulate the expressions of E-cadherin, Bax and Caspase-3 (P<0.05). Conclusion:APS combined with IR can inhibit the migration and invasion of CNE-1 cells, and increase the apoptosis induced by radiotherapy, which may be related to the inhibition of EMT and Akt/ERK pathway.
ABSTRACT
<p><b>OBJECTIVE</b>To find a suitable method for detecting SiO2 in quartz sand and to analyze the influencing factors on infrared spectroscopic determination of the content of free silica in quartz sand.</p><p><b>METHODS</b>The infrared spectroscopy was used to detect the free silica content of quartz sand, the various factors of influencing the results were analyzed and the control scheme was proposed.</p><p><b>RESULTS</b>The number of particles less than 5 um and the proportion of free silica content increased with the grinding time. When the grinding time was 10-20 min, the results of detecting the free silica content tended to be stable. When the ashing temperature was below 550 degrees C, there was no effect on the free silica content. Although the silica content decreased slightly at ashing temperature 600 degrees C as compared to ashing temperature 550 degrees C, the difference of the free silica content between 550 degrees C and 600 degrees C was not significant (P > 0.05). When the ashing temperature was 600 degrees C, the free silica content in quartz sand samples did not change obviously in 1 h (F = 4.231, P > 0.05). The free silica content in quartz sand samples decreased significantly at 2 h of ashing time, as compared with 2 h of ashing time (F = 10.231, P < 0.05). The average content of free silica was 88.56% +/- 5.75% by pyrophosphate determination, which was significantly higher than that (21.23% +/- 11.25%) by infrared determination (P < 0.05). There was no significant correlation of the average content of free silica between pyrophosphate determination and infrared determination (r = 0.411, P > 0.05).</p><p><b>CONCLUSION</b>The free silica contents detected by pyrophosphate determination were significantly higher than those detected by infrared determination for the same quartz sand samples. It is suggested that the method of detecting the free silica contents in quartz sand samples prefers the pyrophosphate determination to infrared determination.</p>