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Objective@#To investigate the effect of ribosomal DNA (rDNA) copy number variation caused by hexavalent chromium exposure on DNA damage response in different cell lines, so as to provide insights into the involvement of hexavalent chromium-induced rDNA copy number variation in DNA damage responses. @*@#Methods Human lung epithelial BEAS-2B cells and human embryonic lung MRC-5 cells were treated with 2 μmol/L potassium dichromate for 24 hours, and then cells were transferred to fresh media for further incubation, while cells treated with the same volume of phosphate buffer solution served as controls. Cells treated with potassium dichromate for 24 hours, and 3 and 7 days post-detoxification, were harvested, and rDNA copy number was quantified in cells using a quantitative fluorescent real-time PCR assay. Cell cycle, apoptosis and DNA damage were detected using a Muse cell analyzer, and the DNA damage was evaluated with the proportion of ataxia telangiectasia-mutated (ATM) gene activation, proportion of double-strand DNA breaks and the percentage of the H2A.X variant histone phosphorylatio.@*@# Results The 45S and 5S rDNA copy numbers of were significantly higher in MRC-5 cells than in BEAS-2B cells [(1.54±0.26) vs. (1.02±0.18), P<0.05; (6.97±1.07) vs. (3.00±0.15), P<0.05]. The 45S rDNA copy number was lower in MRC-5 cells 3 days post-detoxification (0.80±0.04) than in controls (P<0.05), and was higher in BEAS-2B cells 3 days post-detoxification (1.43±0.07) than in controls (P<0.05) . G0/G1 phase arrest was found in MRC-5 cells 24 hours post-treatment, and the apoptotic rates were significantly higher in MRC-5 cells 3 and 7 days post-detoxification than in controls [(11.53±1.53)%, (18.33±0.70)% vs. (3.53±0.93)%, P<0.05]. The overall apoptotic rates 24 hours post-treatment and 3 days post-detoxification [(2.80±0.17)%, (3.33±0.57)% vs. (1.53±0.61)%, P<0.05], proportion of ATM gene activation 3 days post-detoxification [(3.37±0.67%) vs. (1.18±0.22)%, P<0.05], proportion of double-strand DNA breaks 3 days post-detoxification [(4.45±0.85)% vs. (0.97±0.21)%, P<0.05] and percentage of the H2A.X variant histone phosphorylation 3 days post-detoxification [(1.68±0.56)% vs. (0.29±0.06)%, P<0.05] in BEAS-2B cells were higher than in controls. @*Conclusions@#Hexavalent chromium-induced rDNA copy number variation affects DNA damage response in different cell lines. A stronger DNA damage response is found in BEAS-2B cells with a low rDNA copy number, and a relative stable response is observed in MRC-5 cells with a high rDNA copy number.
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Objective @#To investigate the status of occupational stress and analyze its influencing factors among frontline employees working in a chemical fiber manufacturing enterprise, so as to provide insights into the development of occupational stress interventions. @*Methods @#The frontline employees working in a chemical fiber manufacturing enterprise were selected as the study subjects using a cluster sampling method in October 2018. The status of occupational stress was investigated using the Chinese version of the effort-reward imbalance ( ERI ) questionnaire. The influencing factors for occupational stress were identified using a multivariable logistic regression model. @*Results @#A total of 1 780 questionnaires were sent out, and 1 115 valid ones ( 62.64% ) were recovered. Among the 1 115 respondents, there were 427 men ( 38.30% ) and 688 women ( 61.70% ), and 71.22% were at ages of 21 to 39 years. There were 561 respondents with < 1 year of service ( 50.31% ), and the longest length of service was 11 years. In addition, there were 1 069 respondents ( 95.87% ) exposed to high noise, and 346 respondents ( 31.03% ) were diagnosed at a high occupational-stress state and 769 ( 68.97% ) at a low state. Multivariable logistic regression analysis identified 5 years or longer of service ( OR=1.540, 95%CI: 1.057-2.245 ) and exposure to high noise ( OR=1.917, 95%CI: 1.004-3.659 ) as risk factors for occupational stress among frontline employees in the chemical fiber manufacturing enterprise. @*Conclusions @#There are 31.03% of frontline employees at a high occupational-stress state in the chemical fiber manufacturing enterprise, and a high occupational-stress state is associated with exposure to high noise and 5 years or longer of service.
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Objective @#To examine the effect of asbestos exposure on oxidative stress, so as to provide insights into the elucidation of pathogenesis and management of asbestos-related diseases. @*Methods @#Totally 245 subjects were recruited from an asbestos manufacturing area in Zhejiang Province, and their gender, age and history of asbestos exposure were collected through a questionnaire survey. The serum levels of 8-hydroxy-2'deoxyguanosine ( 8-OHdG ), glutathione ( GSH ), malondialdehyde ( MDA ), superoxide dismutase ( SOD ) and total antioxidative capacity ( TAOC ) were measured using an enzyme-linked immunosorbent assay ( ELISA ), and the levels of catalase ( CAT ), peroxiredoxin 2 ( PRX2 ), SOD1, SOD2 and thioredoxin-1 ( TRX1 ) were detected in peripheral white blood cells ( WBCs ) using a liquid-chip assay. Multivariable linear regression analysis was performed to identify the association between asbestos exposure and oxidative stress parameters. @*Results @#There were 50 subjects without a history of asbestos exposure (unexposed group), 102 subjects with asbestos exposure for less than 10 years ( AE<10-year group ) and 93 subjects with asbestos exposure for 10 years and more ( AE≥10-year group ). No significant differences were found among the three groups in terms of age, gender, proportion of smokers or proportion of alcohol consumers ( P>0.05 ). Significantly higher 8-OHdG and MDA in serum, and higher PRX2 in peripheral WBCs were detected in the AE≥10-year group than in the unexposed group ( P<0.05 ); lower GSH and TAOC in serum, and lower CAT in peripheral WBCs were detected in the AE≥10-year group than in the unexposed group ( P<0.05 ); higher 8-OHdG and MDA in serum, and higher PRX2 in peripheral WBCs were detected in the AE≥10-year group than in the AE<10-year group ( P<0.05 ). Multivariable linear regression analysis showed that asbestos exposure significantly correlated with 8-OHdG, MDA and TAOC in serum, and CAT and PRX2 in peripheral WBCs ( P<0.05 ). @*Conclusion @#Asbestos exposure may induce the oxidative stress damage, suggesting that oxidative stress may be involved in asbestos-related diseases.
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Objective@#To analyze the influencing factors for hospitalization of pneumoconiosis patients, so as to provide reference for improving the timeliness of treatment and quality of life in these patients. @*Methods@#The pneumoconiosis patients in Changshan, Wenling and Changxing ( having mining industry ) of Zhejiang Province were selected by stratified and typical sampling methods. Their demographic features, prevalence of pneumoconiosis and hospitalization status were collected by a questionnaire survey. Logistic regression analysis was conducted to analyze the influencing factors for hospitalization. @*Results@#Among 166 pneumoconiosis patients, 122 ( 73.49% ) chose to be hospitalized. The multivariate logistic regression analysis revealed that the patients who scored higher in ED-5Q ( OR=65.821, 95%CI: 3.831-1130.781 )and who would communicate with other pneumoconiosis patients ( OR=3.744, 95%CI: 1.261-11.115 ) were more likely to be hospitalized; the patients who were under the medical insurance for urban employees were more likely to be hospitalized than those who were under the new rural cooperative medical care system ( OR=0.033, 95%CI: 0.007-0.154 ) and others ( OR=0.038, 95%CI: 0.002-0.960 ) . @*Conclusion@#The quality of life, communication with other pneumoconiosis patients and type of medical insurance were the influencing factors for hospitalization of pneumoconiosis patients.