[Baseline survey of psychosocial factors levels and their health effects in a cohort study of natural gas field workers]

Objective: To investigate the level of psychosocial factors in workplace and their health effects among workers in a natural gas field. Methods: A prospective and open cohort of natural gas field workers was established to study the level of workplace psychosocial factors and their health effects, with a follow-up every 5 years. In October 2018, a cluster sampling method was used to conduct a baseline survey of 1737 workers in a natural gas field, including a questionnaire survey on demographic characteristics, workplace psychosocial factors and mental health outcomes, physiological indicators such as height and weight, and biochemical indicators such as blood routine, urine routine, liver function and kidney function. The baseline data of the workers were statistically described and analyzed. The psychosocial factors and mental health outcomes were divided into high and low groups according to the mean score, and the physiological and biochemical indicators were divided into normal and abnormal groups according to the reference range of normal values. Results: The age of 1737 natural gas field workers was (41.8±8.0) years old, and the length of service was (21.0±9.7) years. There were 1470 male workers (84.6%). There were 773 (44.5%) high school (technical secondary school) and 827 (47.6%) college (junior college) graduates, 1490 (85.8%) married (including remarriage after divorce), 641 (36.9%) smokers and 835 (48.1%) drinkers. Among the psychosocial factors, the detection rates of high levels of resilience, self-efficacy, colleague support and positive emotion were all higher than 50%. Among the mental health outcomes evaluation indexes, the detection rates of high levels of sleep disorder, job satisfaction and daily stress were 41.82% (716/1712), 57.25% (960/1677) and 45.87% (794/1731), respectively. The detection rate of depressive symptoms was 22.77% (383/1682). The abnormal rates of body mass index (BMI), triglyceride and low density lipoprotein were 46.74% (810/1733), 36.50% (634/1737) and 27.98% (486/1737), respectively. The abnormal rates of systolic blood pressure, diastolic blood pressure, uric acid, total cholesterol and blood glucose were 21.64% (375/1733), 21.41% (371/1733), 20.67% (359/1737), 20.55% (357/1737) and 19.17% (333/1737), respectively. The prevalence rates of hypertension and diabetes were 11.23% (195/1737) and 3.45% (60/1737), respectively. Conclusion: The detection rates of high level psychosocial factors in natural gas field workers are high, and their effects on physical and mental health remain to be verified. The establishment of a cohort study of the levels and health effects of psychosocial factors provides an important resource for confirming the causal relationship between workplace psychosocial factors and health.

[A case-control study on the relationship between DNA methylation and occupational noise hearing loss]

Objective: To explore the relationship between DNA methylation and occupational noise-induced hearing loss. Methods: A case-control study was conducted. People with hearing loss induced by occupational noise were recruited as the case group and those with normal hearing but still exposed to occupational noise were recruited as the control group. A total of 60 participants were included, of which 30 participants were in the case group and 30 in the control group. The methylation level was detected by 850k genome-wide DNA methylation chip technology. The significance of differential methylated position (DMP) was tested by R-packet 'Champ'. The differential methylated region (DMR) was analyzed by using Champ's Bumphunter algorithm. Cluster profiler was used to analyze the gene list for GO and KEGG pathway enrichment. Results: There was significant difference between two groups in binaural high-frequency average hearing threshold (P<0.05), but there was no significant difference in age, smoking, drinking, hypertension, physical exercise and cumulative noise exposure. The results of DMP and DMR analysis showed that 713875 sites were detected in the case group and the control group, and 439 methylation sites with significant difference, accounting for 0.06%; 650 regions were detected, and 72 methylation regions with significant differences, accounting for 11.08%. Compared with the control group, the results of GO enrichment analysis showed that the case group had statistically significant differences in four pathways: axogenesis of projection neurons in the central nervous system, neuronal development in the central nervous system, axogenesis of neurons in the central nervous system and neuronal differentiation in the central nervous system. KEGG enrichment analysis showed that there were significant differences in sphingolipid metabolism, aldosterone synthesis and secretion, primary bile acid biosynthesis pathway between the case group and the control group. Conclusion: The occurrence of occupational noise-induced hearing loss may be related to the regulation of gene expression related to axogenesis of projection neurons in the central nervous system, development of neurons in the central nervous system, axogenesis of neurons in the central nervous system, differentiation of neurons in the central nervous system, sphingolipid metabolism, aldosterone synthesis and secretion, primary bile acid biosynthesis and gene methylation related to metabolism.

[Effect of occupational stress on depression in gas field workers]

Objective: To explore the occurrence level of depressive symptoms and it's influencing factors among gas field workers. Methods: In October 2018, a cross-sectional study was conducted in 1726 gas field workers from a gas field by using cluster sampling method. Questionaire was used to evaluate the individual factors, depressive symptoms, occupational stress factors and stress regulatory factors. The correlation between depressive symptoms and occupational stress was analyzed. Multivariate logistic regression was used to analyze the influencing factors of depressive symptoms. Results: The depressive symptoms score of gas field workers was 12.00 (7.00, 19.00) point. Correlation analysis revealed that depressive symptoms score was positively related to sleep disorders (r=0.598) , effort (r=0.186) , daily tension (r=0.478) , negative affectivity (r=0.565) , social support (r=0.446) and monotony of work (r=0.484) (P<0.01) . And it was negatively related to reward (r=-0.386) , work stability (r=-0.294) , promotion opportunities (r=-0.258) , positive affectivity (r= -0.310) , self-efficacy (r=-0.312) , contral strategy (r=-0.268) , support strategy (r=-0.209) and job satisfaction (r=-0.398) (P<0.01) . Multivariate logistic regression analysis revealed that sleep disorder, high negative affectivity, low support from colleagues, low support from family, high monotony of work and high daily tension were the risk factors for depressive symptoms of gas field worker (OR=3.423, 95%CI: 2.644-4.397; OR=2.847, 95%CI: 2.200-3.683; OR=1.646, 95%CI: 1.215-2.116; OR=1.496, 95%CI: 1.164-1.923; OR=1.578, 95%CI: 1.227-2.303; OR=1.903, 95%CI: 1.480-2.440; P<0.01) . High work stability, high self-efficacy and high job satisfaction were protective factors for depressive symptoms of gas field workers (OR=0.752, 95%CI: 0.591-0.958; OR=0.590, 95%CI: 0.465-0.749; OR=0.718, 95%CI: 0.516-0.999; P<0.05) . Conclusion: Occupational stress factors have a great influence on the depressive symptoms of gas field workers. Increased work stability, self-efficacy and job satisfaction could reduce the risk of depressive symptoms.

[Correlation between social support and occupational stress among gas production workers in the field]

Objective: To investigate the level of social support and its correlation with occupational stress among gas production workers in the field. Methods: In October 2018, the cluster sampling method was used to perform a cross-sectional survey for 1726 gas production workers in the field, and related data of these workers were collected, including age, education level, marital status, level of social support, and related factors for occupational stress. A Spearman's rank correlation analysis was used to investigate the correlation between social support and occupational stress, and the levels of occupational stress-related factors were compared between the groups with different social support scores. Results: The gas production workers in the field had a median (25th percentile, 75th percentile) social support score of 24.00 (19.00, 28.00) , and there was a significant difference in social support score between the workers with different posts or work shifts (P<0.01) . Social support score was positively correlated with effort, daily stress, negative emotion, and job routinization (P<0.05) and was negatively correlated with job satisfaction, reward, working stability, and promotion opportunity (P<0.05) . The group with a high social support score had significantly higher scores of effort, job routinization, sleep disorders, and daily stress than the other two groups (P<0.01) , and the group with a low social support score had significantly higher scores of reward, self-efficacy, positive affection, and job satisfaction than the other two groups (P<0.01) . Conclusion: High-level social support plays an important role in alleviating occupational stress and protecting mental health among gas production workers in the field.

[Interaction of shift work and psychological capital on abnormal glucose and lipid metabolism among natural gas field workers]

Objective: To explore the interaction between shift work and psychological capital on abnormal glucose and lipid metabolism. Methods: A convenient sampling survey of demographics characteristics, shift work and psychological capital was conducted on 1 415 natural gas field workers by questionnaire in October 2018,and their physiological and biochemical indexes were measured according to standard norms. Multivariate logistic regression model was used to analyze the interaction between shift work and psychological capital on abnormal glucose and lipid metabolism. Results: For 1 415 subjectsthe prevalence of abnormal blood glucose was 21.2%, the prevalence of diabetes was 8.3%.The prevalence of abnormal total cholesterol was 40.4%, the prevalence of hypercholesterolemia was 11.3%.The prevalence of abnormal triglyceride was 41.6%, the prevalence of hypertriglyceridemia was 24.7%.The detection rate of Low-density Lipoprotein was 17.3%, the detection rate of Low-density Lipoprotein was 4.0%, and the detection rate of high-density Lipoprotein was 1.3%. Multiple logistic regression model analysis showed that shift work, the low level of self-efficacy and the low level of optimism was positively associated with abnormal blood glucose, respectively (P<0.05). Shift work was positively associated with abnormal triglyceride (P<0.05). However, there was no interaction between shift work, low self-efficacy, low hope, low resilience, and low optimism on abnormal glucose and lipid metabolism. Conclusion: Shift work was a risk factor of abnormal blood glucose and triglyceride, self-efficacy and optimism were protective factors of abnormal blood glucose. There was no multiplicative interaction between shift work and psychological capital on abnormal glucose and lipid metabolism in the study population.

[Correlation of job monotony and social support on daily hassle: a cross-sectional study based on natural gas field workers]

Objective: To explore the correlation of job monotony and social support on daily hassle. Methods: A convenient sampling survey of demographics characteristics, job monotony, social support and daily hassle was conducted on 1 466 natural gas field workers by questionnaire in October; 2018. Multivariate logistic regression model was used to analyze the correlation of job monotony and social support on daily hassle. Results: The age of 1 466 subjects was (44.47±8.0) years and the length of service was (20.46±5.77) years. There were 258(17.6%), 173(11.8%), 799(54.5%), 120(8.2%) and 116(7.9%) subjects from production and marketing department, processing plant, branch, maintenance department and emergency center respectively. There were 374(25.5%) and 1 092(74.5%) subjects with high and low level of job monotony, and 398(27.1%), 648(44.2%) and 420(28.6%) subjects with high, middle and low level of social support. There were 464(31.7%) and 1 002(68.3%) subjects with high and low daily tension respectively. Compared with the low level of job monotony, the high level of job monotony had a higher risk of daily hassle(OR=4.83,P<0.001), and compared with the high level of social support, the middle and low level of social support had a higher risk of daily hassle(OR=1.25, 2.24,P<0.05). Conclusion: Job monotony and social support were associated with daily hassle.

[Analysis on the effect of sound insulation reconstruction in operation room of steel rolling production line in a steel plant]

Objective: To investigate the effect of sound insulation improvement on the noise exposure of workers in the operation room of hot rolling line for wide and heavy plate. Methods: From September 2019 to September 2017, based on the occupational health Survey, the data of 25 fixed operation rooms and workers in operation rooms of a steel rolling production line were collected retrospectively, the noise exposure levels before and after the improvement of sound insulation were statistically analyzed. Results: The noise exposure value of the workers, the qualified rate of 0 Grade 8 hours equivalent noise (L(EX, 8 h)) ≤85 dB (A) and the qualified rate of the design limit value of the operation room were all higher than those before the modification, the difference was statistically significant (P<0.01) , after the renovation, the Class II and above noise hazards were eliminated, the equivalent continuous a sound level (L(Aeq, 8 h)) >75 dB (A) of the workers in the operation room was 8h, and the noise level in the operation room still did not meet the Ergonomics limit standard. Conclusion: The improvement of sound insulation can effectively improve the working environment of noise workplace operating room and reduce the workers'noise exposure level.

[Prediction of KCNQ4gene polymorphism varies with CNE or noise exposure duration on the Risk of NIHL-Cox model analysis based on cohort study]

Objective: The purpose of this study was to explore the association between gene in the potassium recycling pathway 4 (KCNQ4) polymorphisms and the susceptibility to noise-induced hearing loss (NIHL) , and analysis the effect of cumulative noise exposure (CNE) and noise exposure duration on this association. Methods: A nested case-control study with 1∶1 matched was used based on the cohort of noise exposure in a steel factory. A total of 286 cases were selected as the group of hearing loss and 286 controls were chosen according to the matching standards of same gender, same type of work, age difference ≤ 5 years, noise exposure duration ≤ 2 years. The single nucleotide polymorphisms (SNPs) of rs4660468, rs4660470, rs34287852 in KCNQ4 were genotyped by SNPscan(TM) method. The codominant, dominant and recessive models were established to study KCNQ4 polymorphisms and the susceptibility to NIHL by single-factor conditional logistic regression analysis. The COX regression analysis was used to analyze the risk of developing NIHL in individuals with different genotypes along with the extending of noise exposure duration or CNE. Results: In the case of CNE≤96 dB (A) ·year, the risk of developing NIHL in individuals with TA genotype of rs4660470 was 2.197 times than individuals with TT genotypes (95%CI: 1.032~4.677) , and those with TA+AA and TT genotypes (HR=2.467, 95%CI: 1.025~5.934) With the increase of noise exposure duration, in rs4660470, individuals with TA genotype had a higher risk of suffering NIHL than those with TT genotype (HR=1.461, 95%CI: 1.061~2.011) , individuals with TA and/or AA genotype had a earlier risk of suffering NIHL than those with TT genotype. Conclusion: The mutant allele A of rs4660470 in KCNQ4 may be a risk factor for developing NIHL, CNE≤100 dB (A) ·year or the increase of noise exposure duration may further increase the risk of NIHL.

[Association between GSTP1 gene polymorphisms and susceptibility to noise-induced hearing loss]

Objective: To investigate the association between the single nucleotide polymorphisms (SNPS) at rs1695 and rs6591256 in glutathione S-transferase P1 (GSTP1) gene and susceptibility to noise-induced hearing loss in Chinese Han workers exposed to noise. Methods: Using the 1: 1 nested case-control study and taking 6297 workers exposed to noise in a steel plant in Henan province as the cohort study population in July 2019, we screened those who have been exposed to noise for ≥3 years and whose binaural high frequency (3000, 4000, 6000 Hz) average hearing threshold is ≥40 dB (A) into the case group. The control group was selected according to the matching criteria of the same sex, same type of work, and the age difference was not more than 5 years old, and the working age difference was not more than 2 years. 276 subjects were selected into the case group and the control group respectively. The medium and high throughout single nucleotide polymorphism typing technology (SNPscanTM technology) was used to detect the polymorphism of three nucleotide sites of GSR gene, and conditional logistic regression was used to analyze the relationship between single nucleotide polymorphism (SNP) and NIHL, and the relationship between different polymorphic sites and the risk of NIHL after adjusting covariates. After stratification with different cumulative noise exposure (CNE) , Conditional logistic regression analysis was used to analysis the risk of NIHL at different loci. Results: The mean and standard deviation of age of the selected subjects was (40.28±8.00) , the mean and standard deviation of noise-exposed working years was (18.7±8.92) years. The range of noise exposure levels and comulative noise exposure were 80.05-93.35dB (A) and 86.83-107.92 dB (A) ·year, respectively. Compared with the control group, there were no statistically significant differences in age, noise-exposured working years, intensity of noise exposure, CNE, gender, drinking, hypertension prevalence and noise exposure level in the hearing loss group (P>0.05) , while there were statistically difference in smoking, binaural high-frequency average hearing threshold and binaural speech frequency (P<0.05) . After adjusting for smoking, drinking, hypertension and other factors, in the co-dominant model, compared with GGgenotype, the risk of NIHL was higher in rs1002149 GT genotype and rs2251780 GA genotype (OR=1.558, 95%CI: 1.028-2.361; OR=1.550, 95%CI: 1.020-2.355, P<0.05) ; compared with TT/GT genotype, the rs1002149 TT genotype has a higher risk of developing NIHL (OR=1.494, 95%CI: 1.002-2.228, P<0.05) , while rs3779647 genotype had no relationship with the risk of NIHL (P>0.05) . In the equivalent sound level (L(Aeq)) of noise >85 dB (A) stratification, compared with GG genotype, carrying rs1002149 GT genotype and rs2251780 GT genotype has higher risk of nihl (OR=1.801, 95%CI: 1.093-2.967; OR=1.720, 95%CI: 1.050-2.817, P<0.05) . Haplotype analysis of two sites, rs1002149 and rs2251780, was not found to be related to NIIHL susceptibility. Conclusion: The allele G of rs1695 and rs6591256 may be risk factors of NIHL.

[Relationship research among CDH23 gene and the risk of noise-induced hearing loss]

Objective: To explore the relationship among CDH23 gene variation and the risk of noise-induced hearing loss (NIHL) . Methods: The nested case-control study was performed and this study followed a cohort of 6297 noise-exposed workers in a steel factory of Henan province in China from January 1, 2006 to December 31, 2015. In July 2019, subjects whose average hearing threshold were more than 40 dB in high frequency were defined as the case group, and subjects whose average hearing threshold were less than 35 dB in high frequency and less than 25 dB in speech frequency were defined as the control group. A nested case-control study which included 572 subjects was carried out, in which subjects consisted of 286 cases and 286 controls. 18 single nucleotide polymorphisms (SNPs) in CDH23 were selected and genotyped, then we analyzed the association among SNPs in CDH23, haplotypes in CDH23 and NIHL risk. Logistic regression was performed to analyze the main effects of SNPs and the interactions between CNE and SNPs adjusting cumulative noise exposure (CNE) , smoking, drinking, physical exercise and hypertension. Moreover, the association between haplotypes in CDH23 and NIHL risk were also analyzed. We ananlyzed the relationship amongst different SNP groups and NIHL risk using the generalized multifactor dimensionality reduction (GMDR) method. Results: The results suggested that significant associations were observed for rs3802711, rs3752751, rs3752752, rs11592462, rs10762480, rs3747867 for NIHL overall and/or various CNE strata by adjusting CNE, smoking, drinking, physical exercise and blood pressure. For rs3802711, workers exposure to noise carrying the AA/GA genotype of rs3802711 increased risk of NIHL than those carrying GG genotype (OR=3.121; 95%CI:1.054-9.239, P=0.035) in overall; In the stratified analysis of CNE (>97 dB (A) ·year at rs3802711 locus, workers exposure to noise carrying GA genotype (OR=2.056; 95%CI:1.226~3.448, P=0.006) and GA+AA/GA genotype (OR=2.221; 95%CI:1.340~3.681, P=0.002) increased NIHL risk. For rs11592462, workers exposure to noise carrying the GG genotype of rs11592462 increased risk of NIHL than those carrying CC genotype in overall (OR=3.951; 95%CI:1.104-14.137, P=0.04) ; workers exposure to noise carrying the GG genotype of rs11592462 increased risk of NIHL than those carrying CG+CC genotype in overall (OR=4.06; 95%CI:1.145-14.391, P=0.03) . After adjusting CNE, smoking, drinking, physical exercise and blood pressure, the haplotypes of CDH23 rs1227049, rs10999947, rs3752752, rs3752751, rs10762480, rs3802711, rs11592462, rs10466026, rs4747194, rs4747195 were not associated with the risk of NIHL. GMDR analysis showed no association between SNP combination and NIHL risk after adjusting CNE, smoking, drinking, physical exercise and blood pressure. Conclusion: Gene polymorphisms in CDH23 might associate significantly with the risk of NIHL.

[Association between GPX1 gene polymorphisms and noise-induced hearing loss]

Objective: To identify association between genetic polymorphism in the Glutathione peroxidase 1 gene (GPX1) and noise-induced hearing loss (NIHL) . Methods: A nested case control study was conducted based on a cohort of noise-exposed subjects. 392 cases were selected from the steel factory in Henan Province, 392 matched control subjects for each case were designated on the basis of the matched criterion including same gender, age (±5years) and duration of exposure to noise (±2years) . Two single nucleotide polymorphisms (SNPs) of GPX1 were genotyped by SNPscanTM multiplex SNP genotyping kit. Hardy-Weinberg equilibrium (HWE) tests were performed using Pearson's χ(2) for each SNP among control group, effects of genotypes of GPX1 on NIHL were analyzed by logistic regression. Results: All two SNPs were in HWE. After adjustment for covariates including smoking status, rs1987628 polymorphism was statistically significantly associated with the NIHL risk under codominant and Dominant inheritance models; In the subjects carrying rs1987628 GA genotype had a higher NIHL risk than those carrying the GG genotype, the adjusted OR value was 1.803 (95%CI 1.215-2.676, P=0.003) . And meanwhile, rs1987628 GA+AA genotype had a higher NIHL risk than those carrying the GG genotype, the adjusted OR value was 1.762 (95%CI 1.197-2.593, P=0.004) . Conclusion: It was suggested that genetic polymorphism in the GPX1 gene might be the genetic susceptible factor for NIHL.

[Association between GSTP1 gave polymorphisms and susceptibility to noise-induced hearing loss]

Objective: To investigate the association between the single nucleotide polymorphisms (SNPS) at rs1695 and rs6591256 in glutathione S-transferase P1 (GSTP1) gene and susceptibility to noise-induced hearing loss in Chinese Han workers exposed to noise. Methods: A 1: 2 matched nested case-control study was performed, which based on the cohort of 6297 workers exposed to noise in an iron and steel plant in Henan, China, who were followed up from January 1, 2006 to December 31, 2015. According to the criteria of binaural average high-frequency hearing threshold ≥40 dB, a total of 292 workers were enrolled as hearing loss group; after the adjustment for sex, type of work, age (difference≤5 years) , and working years of noise exposure (difference≤2 years) , according to the criteria of binaural average high-frequency hearing threshold <35 dB, and the speech frequency hearing threshold of any ear at any frequency band ≤25 dB, a total of 584 workers were enrolled as control group. The single nucleotide polymorphisms (SNPs) of rs1695 and rs6591256 in GSTP1 were genotyped by high throughput SNP genotyping assay. Hardy-Weinberg equilibrium of control group was checked. The association between the SNPs at the two loci and susceptibility to NIHL was analyzed. Results: The L(Aeq, 8 h) range of workers exposed to noise was 80.2-98.8 dB (A) . The risk of NIHL in individuals with allele G of rs1695 was 1.291 times of those with allele A (95%CI: 1.042-1.598, P<0.05) . The risk of NIHL in individuals with allele G of rs6591256 was 1.390 times of those with allele A (95%CI: 1.119-1.728, P<0.05) . The risk of NIHL in individuals with AG and GG genotypes of rs6591256 was 1.437 times of those with AA genotype (95%CI: 1.057-1.952, P<0.05) . With the increase of noise exposure duration, individuals with AG and GG genotypes of rs6591256 had a higher risk of NIHL than those with AA genotype (HR=1.273, 95%CI: 1.002-1.616, P<0.05) . Conclusion: The allele G of rs1695 and rs6591256 may be risk factors of NIHL.

[Self-esteem and Occupational Stress Relationship Analysis of 1413 Train Drivers in a Railway Bureau]

Objective: To investigate self-esteem status of train drivers. Methods: By using cluster sampling method, a cross-sectional study was conducted in 1 413 train drivers (including passenger train drivers 301, freight train drivers683, passenger shunting train drivers350, and high speed train drivers79) from a railway bureau. The occupational stressors, strains, self-esteem and personalities were measured using occupational stress instruments and effort-reward imbalance questionnaire. Results: The level of self-esteem is medium ofthe train drivers. Sself-esteem scores among different among different job category (job title) , marry status, age, length of service groups were statistical significance (P<0.01) . Differences of self-esteem among different educational level, exercise, smoking and drinking groups weren't statistical significance (P>0.05) . Correlation analysis revealed that self-esteem score was related positively to job satisfaction (r=0.300) , reward (r=0.842) , working stability (r=0.243) , promotion opportunities (r=0.493) , positive affectivity (r=0.216) , responsibility for human beings (r=0.112) and responsibility for things scores (r=0.108) (P<0.01) , negatively to sleep quality (r=-0.103) , social support (r=-0.212) , role conflict (r=-0.007) , role ambiguity (r=-0.169) , physiological needs (r=-0.115) , daily stress (r=-0.150) , negative affectivity (r=-0.252) , depressive symptoms scores (r=-0.215) (P<0.01) . Nonparametric test found that train drivers of group with low self-esteem score reported higher scores for physiological need, role conflict, role ambiguity, social sleep quality, depressive symptoms, negative affectivity, social support and daily stress scores than the medium and higher groups (P<0.01 or<0.05) . But reword, job satisfaction, positive affectivity, copping stratgy, working stability and promotion opportunities scores were lower than the group of medium and higher groups (P<0.01) . Inter-group conflict scores were insignificance (P>0.05) . Multivariate logistic regression analysis revealed that low low self-esteem for drivers occured the risk of job dissatisfaction about 1.5 times as high as that of drivers with higher self-esteem (OR=1.476) Conclusion: Different types of locomotive drivers get different level of self-esteem. Self-esteem was affected by occupational stress largely.

[Sleep quality and occupational stress relationship analysis of 1413 train drivers in a railway bureau]

Objective: To investigate sleep quality status of train drivers. Methods: By using cluster sampling method, a cross-sectional study was conducted in 1413 train drivers (including passenger train drivers 301, freight train drivers 683, passenger shunting train drivers 350, and high speed train drivers 79) from a railway bureau. The occupational stressors, strains, personalities and sleep quality were measured using occupational stress instruments and effort-reward imbalance questionnaire. Results: The train drivers of poor sleep quality was 48.34%. Sleep quality scores among different among different job category (job title) , exercise, smoking and drinking were statistical significance (P<0.01) . Differences of sleep quality among different educational level, marry status, age, length of service groups weren't statistical significance (P>0.05) . Correlation: analysis revealed that sleep quality score was related negatively to job satisfaction, reward, working stability, promotion opportunities, positive affectivity, esteem and self-esteem scores (r: -0.454, -0.207, -0.329,-0.170, -0.291, -0.103, -0.139, P<0.01 or P<0.05) , positively to social support, effort, role conflict, conflict between groups, conflict in groups, responsibility for person, responsibility for thing, psychological needs, physiological needs, daily stress, negative affectivity, depressive symptoms scores (r: 0.338, 0.524, 0.226, 0.094, 0.182, 0.210, 0.247, 0.190, 0.615, 0.550, 0.345, 0.570, P<0.01) . Nonparametric test found that train drivers of group with high sleep quality score reported higher scores for physiological need, psychological need, effort, role conflict, conflict between groups, social support, daily stress, depressive symptoms, responsibility for person, responsibility for thing, negative affectivity and coping scores than the group of lower sleep quality score (P<0.01) . But reword, job satisfaction, positive affectivity, self-esteem working stability and Promotion opportunities scores were lower than the group of lower sleep quality score (P<0.01) . Multivariate logistic regression analysis revealed the risk for more physiological needs, more effort, more depressive symptoms and more daily stress for drivers occured the risk of poor sleep quality were more than two times as high as that of drivers with less physiological needs, less effort, less depressive symptoms and less daily stress (OR=2.905~2.005) . Conclusions Different types of locomotive drivers get different level of sleep quality. Sleep quality was affected by occupational stress largely. Reducing the occupational stress may contribute to improve the sleep quality of train drivers.

[Change of occupational stress from 1996 to 2012 among train engine drivers]

Objective: To analyze the change of level of occupational stress between 1996 and 2012 among train engine drivers. Methods: the cross-section investigation was conducted by using cluster sampling method, subjects included 1 116 and 1 002 passenger train engine drivers and freight train engine drivers respectively in 1996 and in 2012;occupational stressors, strains, personalities, buffering factors and individual factors were investigated by using Occupational Stress Instruments. Unconditional logistic regression analyses were performed to estimate the associations between job stressors, personalities, buffering factors and individual factors and strains. Multivariate OR(95%CI) were derived from the logistic regression models. Results: From 1996 to 2012, for the passenger train engine drivers the scores of role ambiguity (17.67±5.30 vs.14.11±4.66) increased 25.32%, mental load (10.41±3.56 vs. 16.29±2.08) and physical environment (3.61±2.18 vs. 7.03±1.65) scores decreased 36.10% and 48.64% respectively, sleep disorders (18.04±9.20 vs. 13.35±4.00) and negative affectivity (2.76±1.86 vs. 2.14±1.86) scores increased 33.14% and 28.97% respectively, the differences were statistical significant (P<0.001) . For the freight train engine drivers the scores of sleep disorders (20.33±8.17 vs. 12.47±4.12) and negative affectivity (2.95±1.70 vs. 1.87±1.81) scores increased 57.75% and 60.03% respectively, positive affectivity (2.17±1.60 vs. 2.91±1.50) score decreased 25.43%, the differences were statistical significant (P<0.001) . In general, scores varies in factors related to occupational stress among freight train engine drivers were larger than those among passenger train engine drivers. The risk factor of job dissatisfaction among passenger train drivers in 1996 was insufficient superior support (OR=3.77, 95%CI: 2.23-6.37) , the risk factors in 2012 were insufficient superior support (OR=3.35, 95%CI:1.56-7.17) , poor physical environment (OR=3.61, 95%CI: 1.91-6.80), and fewer positive affectivity (OR=3.47, 95%CI: 1.75-6.82). The risk factor of job dissatisfaction among freight train drivers in 1996 and in 2012 were insufficient superior support (OR (95%CI) were 3.11 (2.31-4.19), 2.59 (1.84-3.65) , respectively). Conclusion: The level of occupational stress among train engine drivers in 2012 was larger than that in 1996, the level of occupational stress among freight train drivers was larger than passenger train drivers, the interventions aimed at reducing occupational stress in the Chinese train engine drivers should take into account promotion for design of job organization and contents and organization management style.

[Association between single nucleotide polymorphismsin human heat shock protein 70 gene and susceptibility to noise-induced hearing loss]

Objective: To investigate the association between the single nucleotide polymorphisms (SNPs) at rs1043618, rs2075800, and rs2763979 in human heat shock protein 70 (HSP70) gene and susceptibility to noise-induced hearing loss (NIHL) . Methods: A case-control study was performed, and 5 934 workers exposed to noise in an iron and steel plant in Henan, China, who underwent physical examination from 2006 to 2015, were enrolled as study subjects. According to the criteria of binaural average high - frequency (3000, 4000, and 6000 Hz) hearing threshold≥40 dB (HL) and monauralaverage speech-frequency (500, 1000, 2000 Hz) hearing threshold≥26 dB (HL) on the basis of binauralhigh frequency loss measured by pure tone audiometry, as well as the exclusion of NIHL, a total of 286 workers were enrolled as hearing loss group; after the adjustment for sex, type of work, age (difference≤5 years) , and working years of noise exposure (difference ≤2 years) , 286 workers were enrolled as control group. A 2 ml blood genomic DNA extraction kit was used to perform DNA extraction for the peripheral blood samples, and a multiple SNP typing kit was used to determine the genotypes at the three loci in 572 samples. The association between the SNPs at the three loci and susceptibility to NIHL was analyzed. Results: In all workers, the equivalent sound level (L(Aeq)) of noise was 75.0~96.8 dB (A) . The hearing loss group had a significantly higher binauralhigh - frequencyhearing threshold than the control group (t=56.908, P<0.05) . With CC+TC genotype as control, TT genotype at rs2763979 in HSP70 gene was associated with the susceptibility to NIHL (OR=1.731, 95%CI 1.021-2.935) . In the group with cumulative noise exposure of 96 dB (A) ·year, TT genotype at rs2763979was associated with the susceptibility to NIHL (OR=5.694, 95%CI 1.256-25.817) . The rs1043618 and rs2075800 loci of HSP70 were not associated with the susceptibility to NIHL (both P>0.05) . After the adjustment for confounding factors including smoking and drinking, haplotype CCT was associated with the susceptibility to NIHL (OR=1.425, 95%CI 1.035-1.961) . Conclusion: TT genotype at rs2763979 of HSP70 gene and haplotype CCT are risk factors for NIHL.

[A cohort study on occupational noise induced hearing loss in workers at an iron and steel plant]

Objective: To analyze the incidence rate of occupational noise-induced hearing loss in noise-exposed workers in an iron and steel plant from 2006 to 2015. Methods: Using a cohort study method, workers exposed to occupational noise from Jan 1, 2006 to Dec 12, 2015 were followed up and the pure tone hearing test was conducted. In total, 6 297 subjects completed two or more physical checks and the pure tone hearing test and were included in the analysis. The noise exposure level at the workplace and the equivalent continuous A-weighted sound pressure level for workers was monitored and the cumulative noise exposure dose was evaluated. The subjects were divided into low, middle and high exposure groups according to the noise exposure level, and the equivalent continuous A-weighted sound pressure level for 8 hours for each group was 80.6-85.0, 85.1-90.0 and 90.1-103.4 dB (A), respectively. While the RR and 95% CI were derived from unconditional logistic regression models. In logistic regression analysis, confounding factors such as age, gender, smoking habit, drinking habit, high temperature exposure and chemical hazards exposure level were controlled. Results: During the follow-up period, 392 cases of occupational noise-induced hearing loss were diagnosed among the 6 297 subjects, with an incidence rate of 6.23%; 318 cases of high-frequency hearing loss were diagnosed, with an incidence rate of 5.05%; and 74 cases of occupational noise-induced deafness were diagnosed, with an incidence rate of 1.18% . The incidence rates of hearing loss among the high, medium and low exposure groups were 9.22% (158/1 737), 6.49% (204/3 142) and 2.08% (30/1 442), respectively; the rates of high-frequency hearing loss were 7.41% (127/1 737), 5.25% (165/3 142) and 1.80% (26/1 442), respectively; and the rates of occupational noise-induced deafness were 1.81% (31/1 737), 1.24% (39/3 142) and 0.28% (4/1 442), respectively. For the groups corresponding to cumulative noise exposure doses of ≤84.99, 85.00- 87.99, 88.00- 90.99, 91.00- 93.99, 94.00- 96.99, 97.00- 100.99, 101.00- 102.99 and ≥103.00 dB (A) · year, the incidence rates of hearing loss were 0 (0/185), 1.22% (2/164), 2.52% (17/674), 3.83% (35/913), 5.80% (106/1 827), 6.02% (67/1 113), 9.20% (95/1 003) and 18.04% (70/388), respectively. Compared with the low exposure group, the RR of hearing loss, high-frequency hearing loss and occupational noise-induced deafness for the high exposure group were 4.78 (95% CI: 3.22- 7.11), 4.36 (95% CI: 2.84- 6.69) and 6.63 (95% CI: 2.33- 18.82), respectively; and for the medium exposure group were 3.27 (95% CI: 2.22-4.82), 3.02 (95% CI: 1.99-4.59) and 4.52 (95% CI: 1.61-12.67), respectively. Conclusion: The incidence rate of hearing loss for workers exposed to noise in an iron and steel plant was related to the cumulative noise exposure dose, gender, age, educational level, smoking habits, drinking habits and exposure to high temperature.

[Social support and occupational stress relationship analysis of 1 413 train drivers in a railway bureau]

Objective: To investigate the social support status of train drivers. Methods: Using cluster sampling, a cross-sectional study was conducted in 1 413 male train drivers (including 301 passenger train drivers, 683 freight train drivers, 85 guest scheduling train drivers, 265 cargo adjustable drivers, and 79 high-speed train drivers) from a railway bureau depot. The survey included individual factors, social support, occupational stressors, strains, personalities, and coping strategy using occupational stress instruments and effort-reward imbalance questionnaire. We compared the difference in social support scores between different drivers, who were divided according to job type and age. Additionally, the correlation between social support score and job strain-related factors was analyzed. The influence of depressive symptoms and job satisfaction were analyzed using a non-conditional logistic multivariate model. Results: The overall average age P(50) (P(25),P(75)) of 1 413 train drivers was 33.92 (27.83,43.58) years. The overall average length of service 12.25 (5.25,22.75) years. A significant difference in social support scores was observed according to job type (H=23.23, P<0.001). The specific scores were passenger driver(27 (23,32)), freight train driver (26 (22,30)), guest scheduling driver (27 (24,30)), cargo adjustable driver (26 (22,31)), and high-speed train driver (30 (26,36)) (P(50)(P(25),P(75))). Additionally, social support scores among different age groups were significantly different (H=6.64, P=0.036). The specific scores were ≤30 years (26 (22,31)), 30-40 years (27 (23,33)), and >40 years (27 (22,31)). Correlation analysis revealed that the social support score was negatively associated with job satisfaction (r=-0.43), reward (r=-0.22), working stability (r=-0.23), promotion opportunities (r=-0.12), positive affectivity (r=-0.31), esteem (r=-0.21), and self-esteem (r=-0.20) scores (P<0.001). The social support score was positively associated with sleep disorders (r=0.33), external effort (r=0.21), pay within (r=0.12), role conflict (r=0.20), conflict between groups (r=0.17), conflict in groups (r=0.06), responsibility for the others (r=0.06), responsibility for things (r=0.08), physiological needs (r=0.39), psychological needs (r=0.19), daily stress (r=0.29), negative affectivity (r=0.23), and depressive symptoms (r=0.44) scores (P<0.05). Multivariate logistic regression analysis revealed social support had a great influence on depressive symptoms and low job satisfaction. Compared with high social support, low social support resulted in depressive symptoms (OR=4.12, 95% CI:3.19-5.33) and low job satisfaction (OR=2.18, 95%CI:1.65-2.88). Conclusion: Train drivers obtained various levels of social support. Social support greatly affected occupational stress. High social support was related to reduction in the occurrence of occupational stress, depressive symptoms, and low job satisfaction. Social support is related to mental health of train drivers.

[Influencing factors for job satisfaction in train drivers in a railway bureau: an analysis of 1413 cases]

Objective: To investigate the influencing factors for job satisfaction in train drivers. Methods: In March 2012, cluster sampling was used to conduct a cross-sectional survey in 1413 male train drivers (including 301 passenger train drivers, 683 freight train drivers, 350 passenger shunting train drivers, and 79 high-speed train drivers) from a locomotive depot of a railway bureau. The occupational stress instruments, job content questionnaire, and effort-reward imbalance questionnaire were used to analyze job satisfaction, occupational stress factors, stress reaction, individual characteristics, coping strategies, and social support. Results: There were significant differences in job satisfaction score between the drivers with different posts, working years, ages, smoking status, and drinking status (P<0.01). The correlation analysis revealed that job satisfaction score was positively correlated with reward, working stability, promotion opportunity, positive emotion, social support, self-esteem, and coping strategy scores (P<0.01) and negatively correlated with sleep disorders, effort, role conflict, intergroup conflict, responsibility for persons, responsibility for things, psychological needs, physiological needs, daily stress, negative emotion, and depressive symptom scores (P< 0.01). The analysis of variance showed that compared with the moderate and low job satisfaction groups, the high job satisfaction group had significantly higher reward, positive emotion, promotion opportunity, and role ambiguity scores (P<0.01) , as well as significantly lower scores of responsibility for persons and responsibility for things (P<0.01). Compared with the moderate and high job satisfaction groups the low job satisfaction group had significantly higher scores of psychological needs, effort, role conflict, sleep disorders, daily stress, depressive symptom, negative emotion, drug use, intragroup conflict, and social support (P<0.01) , and the moderate job satisfaction group had a significantly higher score of self-esteem than the other two groups (P<0.05). The logistic regression analysis showed that the risk of job dissatisfaction in the drivers with low so-cial support and high daily stress was more than 2 times that in those with high social support and low daily stress (OR=2.176 and 2.171) , and sleep disorders, effort, depressive symptom, low self-esteem, and role conflict were risk factors for job dissatisfaction (OR=1.48-1.625). Conclusion: Occupational stress, stress re-sponse, emotion, individual characteristics, and social support have great influence on job satisfaction. Im-proving social support, increasing positive emotion, and reducing occupational stress are main measures for increasing job satisfaction in train drivers.

[Investigation into the relationship between mitochondrial 12 S rRNA gene, tRNA gene and cytochrome oxidase Ⅱ gene variations and the risk of noise-induced hearing loss]

Objective: To explore the relationship between mitochondrial 12 S rRNA gene variation, tRNA gene variation and cytochrome oxidase Ⅱ gene point mutations and the risk of noise-induced hearing loss (NIHL). Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory in Henan province, China, from January 1, 2006 to December 31, 2015. Subjects whose average hearing threshold was more than 40 dB(A) in high frequency were defined as the case group, and subjects whose average hearing threshold was less than 35 dB(A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. Subjects was recruited into the case group (n=286) and the control group (n=286) according to gender, age, job category and time of exposure to noise, and a 1∶1 case-control study was carried out. We genotyped eight single nucleotide polymorphisms in the mitochondrial 12 S rRNA gene, the mitochondrial tRNA gene and the mitochondrial cytochrome oxidase Ⅱ gene using SNPscan high-throughput genotyping technology from the recruited subjects. The relationship between polymorphic sites and NIHL, adjusted for covariates, was analyzed using conditional logistic regression analysis, as were the subgroup data. Results: The average age of the recruited subjects was (40.3±8.1) years and the length of service exposure to noise was (18.6±8.9) years. The range of noise exposed levels and cumulative noise exposure (CNE) was 80.1- 93.4 dB (A) and 86.8- 107.9 dB (A) · year, respectively. For workers exposed to noise at a CNE level<98 dB (A) · year, smokers showed an increased risk of NIHL of 1.88 (1.16-3.05) compared with non-smokers; for workers exposed to noise at a CNE level ≥98 dB(A) · year, smokers showed an increased risk of NIHL of 2.53 (1.49- 4.30) compared with non-smokers. For workers exposed to noise at a CNE level<98 dB (A) · year, the results of univariate analysis and multifactor analysis, adjusted by smoking and CNE, suggested that the risk of NIHL in workers exposed to noise carrying the GG genotype (G827A) was lower than that of NIHL workers exposed to noise carrying the AA genotype (G827A) [OR (95% CI) were 0.18 (0.04- 0.82) and 0.19 (0.04- 0.88), respectively]. Conclusion: Smoking increased the risk of NIHL in the present study. For workers subjected to a CNE<98 dB(A)·year, the mitochondrial genetic variant G827A was found to be significantly associated with the risk of NIHL.

[Influence of occupational stress and 5-hydroxytryptamine 2A receptor gene polymorphisms on depression in workers in a thermal power plant]

Objective: To investigate the association of occupational stress and 5-hydroxytryptamine 2A (5-HT2A) receptor gene polymorphisms with depression. Methods: In November 2010, cluster sampling was used to select 589 workers in a thermal power plant as study subjects. Questionnaires were used to investigate demographic features and occupational stressors. Polymerase chain reaction-restriction fragment length polymorphism was used to detect the genotypes of T102C and A-1438G in 5-HT2A receptor gene in 589 workers. Results: High-level daily hassles (OR=3.013, 95%CI 1.642~5.530) , more negative emotion (OR=4.808, 95% CI 2.662~8.681) , more body needs (OR=1.890, 95% CI 1.034~3.453) , and severe role conflict (OR=1.815, 95% CI 1.002~3.288) were risk factors for depression, while high rewards (OR=0.424, 95% CI 0.226~0.796) was the protective factor against depression (all P<0.05). There were no significant differences in T102C genotype and allele distributions between the groups with and without depression (P>0.05) ; there was a significant difference in A-1438G genotype distribution between the groups with and without depression (χ²= 9.573, P<0.05) , while there was no significant difference in A-1438G allele distribution between these groups (P>0.05). The risk of depression in the workers with high-level daily hassles who carried TC genotype (OR= 4.473, 95% CI 1.161~17.238) or CC genotype (OR=5.176, 95% CI 1.367~19.593) of T102C was 4.473 and 5.176 times that in those with low-level daily hassles who carried TT genotype, and the risk of depression in the workers with more negative emotions who carried TC genotype (OR=5.667, 95%CI 1.204~26.673) or CC genotype (OR=8.114, 95% CI 1.747~37.677) of T102C was 5.667 and 8.114 times that in those with less negative emotion who carried TT genotype. The risk of depression in the workers with high-level daily hassles who carried AG genotype (OR=4.505, 95% CI 2.215~9.162) or GG genotype (OR=6.484, 95% CI 2.562~ 16.414) of A-1438G was 4.505 and 6.484 times that in those with low-level daily hassles who carried AA genotype, and the risk of depression in the workers with more negative emotion who carried AG genotype (OR= 4.877, 95%CI 2.326~10.223) or GG genotype (OR=9.090, 95%CI 3.491~23.673) of A-1438G was 4.877 and 9.090 times that in those with less negative emotion who carried AA genotype. The risk of depression in the workers with higher rewards who carried AG genotype (OR=0.152, 95%CI 0.074~0.310) or GG genotype (OR= 0.384, 95% CI 0.153~0.964) of A-1438G was 0.152 and 0.384 times that in those with lower rewards who carried AA genotype. Conclusion: Occupational stress is associated with the development of depression and interacts with 5-HT2A receptor gene polymorphisms.

[Association between grainyhead-like 2 gene polymorphisms and noise-induced hearing loss]

OBJECTIVE

To investigate association between genetic polymorphism in the grainyhead-like 2 gene (GRHL2) and noise-induced hearing loss (NIHL) in the Chinese population.

METHODS

A matched case-control association study was employed, In which, 3 790 workers exposed to continuous and steady-state occupational noise in a steel factory participated. The questionnaires were adopted to collect individual features and audiometry tests performed. In the sstudy, 286 subjects were diagnosed as cases, Which were each designated on the basis of the matched criterion, and 286 paired samples were selected finally. Noise intensity was measured according to the standards given in 'Measurement of Noise in the Workplace'(Occupational Health Standard of the People's Republic of China, GBZ/T189.8-2007). Cumulative noise exposure (CNE) was calculated, according to monitoring data on A-weighed sound pressure level and employment time. Genomic DNA was obtained from peripheral blood samples using 2 mL DNA extraction Kit following the manufacturer's protocol. Five single nucleotide polymorphisms (SNPs) of GRHL2 were genotyped by multiplex SNP genotyping kit. The continuous variables and categorical variables were analyzed by t-test and chi-square test respectively. Multivariate Logistic regression was used to test the association between genetic frequency and disease status, with adjustments for the possible confounding variables. The haplotypes were established and their frequencies in the two groups were assessed by haploview and phase softwares.

RESULTS

All the five SNPs (rs3735713, rs3824090, rs3735714, rs3735715 and rs611419) were in Hardy-Weinberg equilibrium (HWE) (P>0.05). The subjects carrying rs3735715 GG genotype had a higher NIHL risk than those carrying the GA genotype under the co-dominant model (OR=0.644, 95% CI: 0.442-0.939, P=0.022) after adjustment for height, blood pressure, drinking status and smoking status. After being stratified by CNE, in the CNE ≥ 98 dB (A) group, rs3735715 polymorphism was associated with the NIHL under the co-dominant model (OR=0.509, 95% CI: 0.281-0.923, P=0.026) after adjustment for height, blood pressure, drinking status and smoking status as well. However, no statistical significant difference was found in variant genotypes of the other SNPs between the case and control subjects. Four-locus (rs3735713, rs3824090, rs3735714 and rs3735715) haplotypes were constructed, and no risk or protective haplotypes was identified.

CONCLUSION

It is suggested that GRHL2 polymorphisms may be associated with development of NIHL.

[Factors influencing electrocardiogram results in workers exposed to noise in steel-making and steel-rolling workshops of an iron and steel plant]

OBJECTIVE

To investigate the factors influencing the electrocardiogram results in the workers exposed to noise in steel-making and steel rolling workshops of an iron and steel plant.

METHODS

From September to December, 2013, cluster sampling was used to select 3 150 workers exposed to noise in the steel-making and steel-rolling workshops of an iron and steel plant, and a questionnaire survey and physical examinations were performed. The number of valid workers was 2 915, consisting of 1 606 workers in the steel-rolling workshop and 1 309 in the steel-making workshop. The electrocardiogram results of the workers in steel-making and steel-rolling workshops were analyzed.

RESULTS

The overall abnormal rate of electrocardiogram was 26.35%, and the workers in the steel-making workshop had a significantly higher abnormal rate of electrocardiogram than those in the steel-rolling workshop(32.24% vs 21.54%, P<0.05). Male workers had a significantly higher abnormal rate of electrocardiogram than female workers(27.59% vs 18.61%, P<0.05). The workers with a drinking habit had a significantly higher abnormal rate of electrocardiogram than those who did not drink(28.17% vs 23.75%, P<0.05). The workers exposed to high temperature had a significantly higher abnormal rate of electrocardiogram than those who were not exposed to high temperature(29.43% vs 20.14%, P<0.05). The abnormal rates of electrocardiogram in the workers with cumulative noise exposure levels of <90, 90~94, 95~99, 100~104, and 105~113 dB(A)·year were 21.21%, 21.76%, 26.50%, 27.27%, and 32.16%, respectively, with significant differences between any two groups(P<0.05). The multivariate logistic regression analysis showed that a cumulative noise exposure of 105-113 dB(A)·year(OR=1.36, 95% CI: 1.03~1.80), a drinking habit(OR=1.20, 95% CI: 1.01~1.43), and high temperature(OR=1.60, 95% CI: 1.32~1.92) were the risk factors for abnormal electrocardiogram results.

CONCLUSION

High cumulative noise exposure, alcohol consumption, and high temperature may affect the abnormal rate of electrocardiogram in the workers exposed to noise in steel-making and steel-rolling workshops.

[Correlation of occupational stress with serum levels of immunoglobulins and complement in police]

OBJECTIVE

To investigate the correlation of occupational stress with the serum levels of immunoglobulins(IgG, IgM, and IgA) and complement(C3 and C4).

METHODS

In May 2011, convenience sampling and cluster sampling were used to select 225 policemen from a local police station as study subjects. A questionnaire was used to investigate demographic features and occupational stress, and the immunoturbidimetric assay was applied to measure the serum levels of IgG, IgM, IgA, and complement C3 and C4.

RESULTS

Positive affectivity was positively correlated with the concentration of IgG(r=0.084, P<0.01); positive affectivity, coping strategy, and sleep quality were positively correlated with the concentration of IgM(r= 0.146, 0.155, and 0.203, all P<0.05); negative affectivity was negatively correlated with the concentration of IgM(r=-0.185, P<0.05). Reward and sleep quality were positively correlated with the concentration of C3(r= 0.172 and 0.285, both P<0.05), and negative affectivity was negatively correlated with the concentration of C3 (r=-0.174, P<0.05); sleep quality was positively correlated with the concentration of C4(r= 0.173, P<0.05), and negative affectivity was negatively correlated with the concentration of C4(r=-0.164, P<0.05). The logistic regression analysis revealed that the risks for a reduced concentration of IgG in the groups with high scores of social support and positive affectivity were 0.460 and 0.495 times those in the groups with low scores, while the risk for a reduced concentration of IgM in the group with a high score of coping strategy was 0.482 times that in the group with a low score.

CONCLUSION

Occupational stress is correlated with the serum levels of immunoglobulins and complement.

Protective effect of bifemelane on c-Fos-like immunoreactivity in rat cerebral ischemia

Cytoprotection by bifemelane hydrochloride was investigated immunohistochemically in the cerebral cortex of rats during ischemia. The middle cerebral artery was occluded for 30 min and then reperfused for 6 h. c-Fos-like immunoreactive neurons were found in layers II to VI of the cerebral cortex and were especially abundant in the parietal cortex and the piriform cortex on the side of the occlusion. In sham-operated control rats, a few c-Fos-like immunoreactive neurons were seen in the ipsilateral side of the cerebral cortex. In animals that had been injected with bifemelane hydrochloride (20 mg/kg, IP) 30 min before the onset of ischemia and 90 min after reperfusion, the number of c-Fos-like immunoreactive neurons was significantly reduced in the cerebral cortex. The results suggest that bifemelane hydrochloride can inhibit the ischemia-induced increase in c-Fos-like immunoreactivity in cerebral cortex neurons.