[Effect of hOGG1 expression level on oxidative DNA damage among workers exposed to nickel in stainless steel production environment].

OBJECTIVE: To study the excision repair capacity of human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) for 8-OH-dG and the oxidative DNA damage among workers exposed to nickel in stainless steel production environment. METHODS: A total of 231 workers exposed to nickel in a stainless steel production enterprise were recruited as nickel exposure group, and another 75 water pump workers in that enterprise were recruited as control group. The workplace occupational hazard factors were determined. Double-antigen sandwich ELISA was used to determine urinary 8-OH-dG level; RT-PCR was used to determine hOGG1 mRNA level. Pearson correlation was used to analyze the correlation between urinary 8-OH-dG level and hOGG1 mRNA level. RESULTS: Level of 8-OH-dG was compared between different types of nickel-exposed workers and control workers; rolling mill workers showed no significant difference from the control group (P > 0.05), while steel making workers and steel slag disposing workers showed significant differences from the control group (P < 0.05). Level of 8-OH-dG was also compared between nickel-exposed workers with different working years and control workers; nickel-exposed workers with 0∼5 and 6∼10 working years showed no significant differences from the control group (P > 0.05), while other exposed workers showed significant differences from the control group (P < 0.05). Different types of nickel-exposed workers all showed significant differences from the control group in hOGG1 mRNA level (P < 0.05). Nickel-exposed workers with 0∼5 working years showed no significant difference from the control group in hOGG1 mRNA level (P > 0.05), while other exposed workers showed significant differences from the control group (P < 0.05). Pearson correlation analysis showed that urinary 8-OH-dG level was positively correlated with hOGG1 mRNA level (r = 0.993) in different types of nickel-exposed workers, and the correlation was significant at α = 0.01 (P < 0.05); urinary 8-OH-dG level also showed a positive correlation with hOGG1 mRNA level in nickel-exposed workers with different working years (r = 0.968), and the correlation was significant at α = 0.01 (P < 0.05). CONCLUSION: Exposure to nickel increases oxidative DNA damage among steel workers, and hOGG1 shows active excision repair capacity for 8-OH-dG.

Relationship between urinary nickel and methylation of p15, p16 in workers exposed to nickel.

OBJECTIVE: The purpose of this study was to investigate the relationship between urinary nickel and methylation of p15, p16 in workers exposed to nickel. METHODS: In this study, 165 nickel-exposed workers and 67 workers without exposure were recruited. The levels of urinary nickel were analyzed using dimethylglyoxime spectrophotometric method. Methylation-specific polymerase chain reaction was used to detect the methylation of p15 and p16. RESULTS: The median concentration of urinary nickel in the exposed group (4.58 µg/L) was significantly higher than that in the control group (1.78 µg/L; P < 0.01). The rate of methylation of p15 in the exposed group was significantly higher than that in the control group (P = 0.023). The multiple logistic analysis showed that workers having higher urinary nickel were at the higher risk of methylation of p15 (P = 0.024). CONCLUSIONS: The levels of urinary nickel were significantly associated with the methylation of p15.

[The relationship between single nucleotide polymorphisms of JWA gene and susceptibility to hypertension in workers exposed to heat stress].

OBJECTIVE: To study the relationship between JWA polymorphisms and the susceptibility to hypertension in workers exposed to heat stress. METHODS: The exposure group included 158 steelworkers and rollers and 76 workers unexposed to heat stress served as control group. The general information was collected according to a questionnaire and the blood pressure was examined for all subjects. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to analyze the site 76 in promoter and site 723 in the 3rd exon of JWA gene in the peripheral lymphocytes. PHASE 2.0 software was utilized to calculate the haploid type. RESULTS: In the exposure group, JWA76 G/G genotype frequencies of sub-group with normal blood pressure, sub-group with higher blood pressure and sub-group with hypertension were 82.35%, 69.70% and 65.00%, respectively, there were significant differences among 3 sub-groups (P < 0.05). JWA 76 G/G genotype frequencies decreased with blood pressure (χ² = 4.86, P = 0.027). The multiple logistic regression analysis showed that the subjects with G/C genotype were compared to the subjects with G/G genotype in the exposure group, the adjusted OR value was 3.67 (95%CI: 1.21 approximately 11.05) for the risk of hypertension and higher blood pressure. the subjects with GG/CT haploid type were compared to the subjects with non-GG/CT haploid type in the exposure group, the adjusted OR values for the risks of hypertension and higher blood pressure were 8.30 (1.39 approximately 49.44) and 8.55 (1.53 approximately 47.48), respectively. CONCLUSION: The gene polymorphisms at site 76 and GG/CT haploid type of JWA gene were associated with hypertension in workers exposed to high temperature.

[Relationship between CYP1A1 gene polymorphisms and urinary 1-hydroxypyrene levels in coke oven workers].

OBJECTIVE: To study the associations of CYP1A1 gene polymorphisms with levels of urinary 1-hydroxypyrene among coke oven workers. METHODS: 223 male workers from a coke plant (76, 82 and 65 workers in oven top group, oven-side group and oven-bottom group respectively) and 119 controls without occupational polycyclic aromatic hydrocarbons exposure were selected. The MspI gene polymorphism in CYP1A1 3' flanking region and the genotypes at I462V site in exon 7 of CYP1A1 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele specific amplification (ASA). RESULTS: The urinary 1-hydroxypyrene of coke oven workers in oven-top, oven-side and oven-bottom (3.77+/-0.64, 3.57+/-0.49, 3.26+/-0.80 micromol/mol Cr) were significantly higher than controls (2.80+/-1.02 micromol/mol Cr) (P<0.01). The urinary 1-hydroxypyrene was not significantly different among MspI genotypes in CYP1A1 3' flanking region (P>0.05). In oven-top group and oven-side group, the subjects with Val/Val genotype in exon 7 of CYP1A1 had significantly higher urinary 1-hydroxypyrene levels than those with Ile/Val or Ile/Ile genotype, and urinary 1-hydroxypyrene of Ile-Val genotype were also significantly higher than Ile/Ile genotype (P<0.01). Multivariate logistic regression analysis showed that the coke oven workers (OR in oven top group, oven-side group and oven-bottom group was 24.926, 4.226 and 6.729 respectively) and subjects with m2/m2 genotype in CYP1A1 3' flanking region (OR=4.031) or with Val/Val or Ile/Val genotype in exon 7 of CYP1A1 (OR were 5.524 and 3.811) had elevated urinary 1-hydroxypyrene (greater than 95 percentile of control group, 3.876 micromol/mol Cr). CONCLUSION: BAP concentration of work environment contributes to the elevated urinary 1-hydroxypyrene levels, and the exposed BAP levels were regulated by the CYP1A1 MspI and I462V genotypes. Genetic polymorphism of CYP1A1 gene could be a susceptible biomarker in coke oven workers which was involved in the individual susceptibility on metabolism of PAHs.

[Characteristic of the neurobehavioral functional changes in coke oven workers].

OBJECTIVE: To explore the effect of polycyclic aromatic hydrocarbons on the neurobehavioral function of coke oven workers. METHODS: 200 healthy adult male coke oven workers were selected from a coke plant of a state-owned steel enterprise in Taiyuan City. 88 controls occupationally unexposed to polycyclic aromatic hydrocarbons (PAHs) were selected from the same enterprise. All the subjects participated in this investigation voluntarily in their consent. Concentration of B(a)P in the working environment was monitored by High Performance Liquid Chromatography (HPLC). Urine samples were sampled immediately after working shifts. The level of urinary 1-hydroxypyrene was determined by HPLC. General information of workers correlated with the investigation was collected in a questionnaire according to the same criteria by well-trained investigators. Neurobehavioral core test battery (NCTB) recommended WHO was performed on coke oven workers and controls to test the neurobehavioral changes and the mood state. RESULTS: the concentration of B(a)P at oven bottom,oven side and oven top were 0.0195 microg/m3, 0.186 microg/m3 and 1.624 microg/m3 respectively, that at oven side and oven top being higher than the one stipulated by the occupational hygiene criterion. Urinary 1-hydroxypyrene was significantly different between the exposure group (3.42 +/- 0.98 micromol/mol creatinine) and control group (2.75 +/- 1.09 micromol/mol creatinine). No significant differences were found between exposure group and control group of age, working years, smoking, drinking and unhealthy food consumption; however, compared to the controls, the scores of total digital span, the forward digital span, and right dotting in the coke oven workers were lower, but that of total dotting was higher, with a statistical significance. According to urinary 1-hydroxypyrene concentration, all the subjects were divided into three groups. (<3.10 micromol/mol creatinine, 3.10 micromol/mol creatinine, >3.87 micromol/mol creatinine). Significant differences of the total digital span, the forward digital span, backward digital span, digit symbol and Benton visual retentions existed in different urinary 1-hydroxypyrene concentration groups and showed a dose-response tendency. Results of multiple stepwise regression analysis and correlation analysis showed that the level of urinary 1-hydroxypyrene affected memory and perception of coke oven workers and negative correlations between the level of urinary 1-hydroxypyrene and changes in neurobehavioral function were found. CONCLUSION: PAHs mainly causes decrease of memory and perception in coke oven workers.

[Relationship between the expression of heat shock protein and genetic damage in peripheral blood of workers exposed to coke oven emissions].

OBJECTIVE: To explore the relationship between the expression of heat shock protein 90, 60 and 27 (HSP90, HSP60 and HSP27) and genetic damage in peripheral blood of workers exposed to coke oven emissions. METHODS: 288 coke oven workers in a steel factory were divided into the high-dose group and the low-dose group on the basis of environment monitoring result and work place. There were 172 men in high-dose group (workers who worked at the oven top and oven side) and 116 men in low-dose group (workers who worked at the oven bottom and others who were engaged to aided work). 38 workers unexposed occupationally to carcinogenic substances were selected as the control group, who were employed in medical therapy unit nearby 2 kilometers from the steel factory. Their general information, history of personal and occupational exposure, and the work environment were investigated. Blood samples were collected immediately after a shift at the end of a working day from 288 coke oven workers and 38 control workers. Levels of HSP90, HSP60 and HSP27 in peripheral blood lymphocytes were measured by Western blot, and the degree of DNA damage was detected by the comet assay. RESULTS: Levels of HSP90 in peripheral blood lymphocytes in three groups were 0.24 +/- 0.32, 0.12 +/- 0.30 and 0.06 +/- 0.33 respectively. They increased significantly compared with that of the control. But levels of HSP60 and HSP27 were not significantly different among those groups. Compared with the control group, there was significant difference in tail length, olive tail moment et al of SCGE (G +/- s(G)) of occupational exposure workers. High-dose group > low-dose group > control group (P < 0.05). The degree of DNA damage increased with the rise of exposure BaP dose (Spearman r = -0.345, P < 0.01). CONCLUSION: Levels of HSP90 in peripheral blood lymphocytes and the degree of DNA damage increase with the rise of exposure polycyclic aromatic hydrocarbons (PAHs) dose.

[Relationship between aryl hydrocarbon receptor G1661A gene polymorphism and level of urinary 1-hydroxypyrene of coke oven workers].

OBJECTIVE: To study the relationship between polymorphism of aryl hydrocarbon receptor (AhR) gene in G1661A and the level of urinary 1-hydroxypyrene among coke oven workers. METHODS: 295 male subjects were studied, including 214 workers working in coke oven plant and 81 controls working in raw material plant who were not generally exposed to polycyclic aromatic hydrocarbons occupationally. General in-formation of subjects were collected in a specific questionnaire including age, smoking and drinking habits, the history of occupation and so on. The AhR genotypes were detected by allele specific amplification (ASA), and the levels of urinary 1-hydroxypyrene were measured by high performance liquid chromatography with a fluorescence detector. RESULTS: The frequencies of G/G, G/A and A/A genotype were 52.8% (113/214), 27.6% (59/214) and 19.6% (42/214) in exposed group and 67.9% (55/81), 19.8% (16/81) and 12.3% (10/81) in control group, respectively. No significant difference was found in three genotypes between the exposed and control group. Allele frequencies of G and A were 66.6% (285/428) and 33.4% (143/428) in exposed group and 77.8% (126/162) and 22.2% (36/162) in control group, and no statistical differences were found in allele frequency between exposed and control group. After the length of service and external exposure orders in general linear model were adjusted, results of covariance analysis showed that logarithmic transformed urinary 1-hydroxypyrene levels were (3.62 +/- 0.12), (3.43 +/- 0.12) and (3.44 +/- 0.08) micromol/mol Cr in individuals with A/A, G/A and G/G, respectively. The logarithmic transformed urinary 1-hydroxypyrene levels were (3.24 +/- 0.09) and (3.43 +/- 0.10) micromol/mol Cr in individuals with allele of G and A. No statistical differences were found in level of 1-hydroxypyrene among A/A, G/A and G/G genotype individuals, and between allele G and allele A after external exposure orders and length of service were adjusted. CONCLUSION: The polymorphism of aryl hydrocarbon receptor G1661A has no significant impact on levels of urinary 1-hydroxypyrene.

PAH-DNA adducts in a Chinese population: relationship to PAH exposure, smoking and polymorphisms of metabolic and DNA repair genes.

The present study was conducted in a Chinese population to evaluate the usefulness and sensitivity of PAH-DNA adduct as a biomarker of PAH exposure, and to examine the potential effects of smoking and polymorphisms of responsive genes on DNA adduct formation induced by PAH exposure. The polymorphisms of genes examined include GSTM1, GSTT1, CYP1A1, microsomal epoxide hydrolase (mEH) and excision repair cross-complementary group 2 (ERCC2). A total of 194 subjects with a broad range of PAH exposures were recruited, including 116 occupationally exposed workers, 49 metropolitan residents and 29 suburban gardeners. A significant exposure-response relationship was observed between PAH exposure and DNA adducts in leukocytes across the entire group of subjects (p < 0.0001). The levels of PAH-DNA adducts in the subgroup with lowest occupational exposure to PAHs (< 0.1 microg BaP m(-3)) was significantly higher than that in metropolitan residents and suburban gardeners. However, no significant difference was detected between residents and gardeners, with mean BaP concentrations of 0.028 and 0.011 microg m(-3), respectively. The polymorphisms of genes examined failed to show significant effects on PAH-induced adduct formation except ERCC2 Lys751Gln genotypes. A significantly higher level of PAH-DNA adduct was found in subjects with wild-type ERCC2 than those who have either heterozygous or homozygous variant alleles (p < 0.01). Smoking, age and gender did not substantially contribute to PAH-induced DNA adduct formation in this study. The study suggests that PAH-DNA adducts may serve as a reliable biomarker of PAH exposure in occupational settings but may not be sensitive enough to be used in populations with environmental exposures to PAHs.

Using lymphocyte and plasma Hsp70 as biomarkers for assessing coke oven exposure among steel workers.

BACKGROUND: Hsp70, an early-response protein induced when organisms are confronted with simple or complicated environmental stresses, can act as either a cellular protector or a danger signal. OBJECTIVES: The goal of this study was to evaluate levels of lymphocyte and/or plasma Hsp70 as biomarkers for assessing exposure response to complex coke oven emissions (COEs). METHODS: We recruited 101 coke oven workers and determined levels of polycyclic aromatic hydrocarbon (PAH) exposure, urinary 1-hydroxypyrene (1-OHP), genotoxic damage by comet assay and micronuclei test, and other markers of damage, including plasma malondialdehyde (MDA) and lactate dehydrogenase (LDH). These were compared to levels of lymphocyte (intra-cellular) and plasma (extracellular) Hsp70 using Western blots and enzyme-linked immunosorbent assays (ELISA), respectively. RESULTS: We observed a COEs-related dose-dependent increase in levels of DNA damage, micronuclei rate, MDA concentration, and LDH activity. Lymphocyte Hsp70 levels increased in the intermediate-exposure group (1.39 +/- 0.88) but decreased in the high-exposure group (1.10 +/- 0.55), compared with the low-exposure group. In contrast, plasma Hsp70 levels progressively increased as the dose of exposure increased. Negative correlations were seen between lymphocyte Hsp70 levels and olive tail moment and LDH activity in the intermediate- and high-exposure groups. However, we observed positive correlations between plasma Hsp70 levels and LDH activity in the low and intermediate groups. CONCLUSIONS: In workers exposed to COEs, high lymphocyte Hsp70 levels may provide protection and high plasma Hsp70 levels may serve as a danger marker. Larger validation studies are needed to establish the utility of Hsp70 as a response marker.

[Relationship between heat shock protein 72 and DNA genetic damage in peripheral blood lymphocytes of coke oven workers].

OBJECTIVE: To investigate the relationship between heat shock protein 72 (Hsp72) and DNA genetic damage in peripheral blood lymphocytes of coke oven workers and the role of Hsp72 in protection of cells from genetic damage induced by coke oven emissions. METHODS: Two hundred and sixty-seven coke oven workers and thirty controls without occupational PAHs exposure were investigated. Benzo[a]pyrene concentrations in the ambient air individually collected were assayed by high performance liquid chromatography (HPLC). Western Blot was used to measure Hsp72 levels and Comet assay was used to evaluate DNA damage degree. Personal information was collected by questionnaire. RESULTS: The Hsp72 level (G+/-S(G)) and olive comet tail moment (G+/-S(G) of peripheral blood lymphocytes in high-exposure workers (1.24 +/- 0.42 and 4.49 +/- 1.24) were significantly higher than those in low-exposure workers (1.01 +/- 0.35 and 2.99 +/- 1.10, P < 0.05) and control (0.85 +/- 0.34 and 2.40 +/- 1.00, P < 0.05) respectively. The Hsp72 median level of all subjects was used as the limit to divide subjects into high Hsp72 level group and low Hsp72 level group. The rate with high Hsp72 level was 36.7%, 43.1% and 58.3% in control, low exposure and high exposure workers respectively and had a rising tendency following exposure level (P = 0.003). In high Hsp72 level group Hsp72 level in high exposure workers was significantly higher than that in control (P < 0.05), and there was a rising tendency along with the increase of exposed levels. But the olive comet tail moment had no significant difference among three exposed groups (P > 0.05). In low Hsp72 level group there no difference among three exposed groups about Hsp72 levels. The olive comet tail moment in high exposure workers was significantly higher than that in low exposure workers and control (P < 0.01) and high exposure workers in Hsp72 positive group and there was a rising tendency along with the increase of exposed levels. Hsp72 levels had strong negative correlation with the olive comet tail moment (r = -0.503, P < 0.01) in high exposure workers. CONCLUSION: The coke oven emissions can induce hsp72 expression. Hsp72 play a role of protecting cells from DNA damage induced by coke oven emissions.

Association between plasma BPDE-Alb adduct concentrations and DNA damage of peripheral blood lymphocytes among coke oven workers.

OBJECTIVES: Coke oven emissions (COE) containing polycyclic aromatic hydrocarbons (PAHs) can induce both benzo[a]pyrene-r-7, t-8, t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts and DNA damage. However, the relation between these biomarkers for early biological effects is not well documented in coke oven workers. METHODS: In this study, the authors recruited 207 male workers exposed to COE and 102 controls not exposed to COE in the same steel plant in northern China. They measured BPDE-Alb adduct concentrations in plasma with reverse-phase high performance liquid chromatography and DNA damage in peripheral blood lymphocytes with alkaline comet assay. RESULTS: The results showed that the median concentration of BPDE-Alb adducts in the exposed group (34.36 fmol/mg albumin) was significantly higher than that in the control group (21.90 fmol/mg albumin, p = 0.012). The mean Olive tail moment (Olive TM) of DNA damage in the exposed and control groups were 1.20 and 0.63, respectively (p = 0.000). Multivariate logistic regression analysis revealed that the odds ratio (OR) for BPDE-Alb adduct and Olive TM associated with the exposure were 1.72 (95% CI 1.06 to 2.81) and 1.96 (95% CI 1.20 to 3.19), respectively. These results show significant correlations between the concentrations of BPDE-Alb adduct and Olive TM levels in exposed group (r = 0.235, p = 0.001) but not in control group (r = 0.093, p = 0.353). CONCLUSION: The results suggest that occupational exposure to COE may induce both BPDE-Alb adducts and DNA damage in the lymphocytes of coke oven workers and that these two markers are useful for monitoring exposure to COE in the workplace.

Association of polymorphisms in AhR, CYP1A1, GSTM1, and GSTT1 genes with levels of DNA damage in peripheral blood lymphocytes among coke-oven workers.

Accumulating evidence has shown that both DNA damage caused by the metabolites of polycyclic aromatic hydrocarbons (PAH) and genetic polymorphisms in PAH-metabolic genes contribute to individual susceptibility to PAH-induced carcinogenesis. However, the functional relevance of genetic polymorphisms in PAH-metabolic genes in exposed individuals is still unclear. In this study of 240 coke-oven workers (the exposed group) and 123 non-coke-oven workers (the control group), we genotyped for polymorphisms in the AhR, CYP1A1, GSTM1, and GSTT1 genes by PCR methods, and determined the levels of DNA damage in peripheral blood lymphocytes using the alkaline comet assay. We found that the ln-transformed Olive tail moment (Olive TM) values in the exposed group were significantly higher than those in the control group (P < 0.001). Furthermore, in the exposed group, the Olive TM values in subjects with the AhR Lys(554) variant genotype were higher than those with the AhR Arg(554)/Arg(554) genotype (P = 0.021). Similarly, the Olive TM values in the non-coke-oven workers with the CYP1A1 MspI CC + CT genotype were lower than the values of those with the CYP1A1 MspI TT genotype (P = 0.005). However, these differences were not evident for GSTM1 and GSTT1. These results suggested that the polymorphism of AhR might modulate the effects of PAHs in the exposed group; however, the underlying molecular mechanisms by which this polymorphism may have affected the levels of PAH-induced DNA damage warrant further investigation.

Elevated levels of urinary 8-hydroxy-2 -deoxyguanosine, lymphocytic micronuclei, and serum glutathione S-transferase in workers exposed to coke oven emissions.

To investigate associations among occupational exposure to coke oven emissions (COEs), oxidative stress, cytogenotoxic effects, change in the metabolizing enzyme glutathione S-transferase (GST), and internal levels of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers, we recruited 47 male coke oven workers and 31 male control subjects from a coke oven plant in northern China. We measured the levels of 1-hydroxypyrene (1-OHP) and 8-hydroxy-2 -deoxyguanosine (8-OHdG) in urine, micronucleated binucleated cells (BNMNs) in peripheral blood lymphocyte, and GST in serum. Our results showed that the group exposed to COEs had significantly increased levels of 1-OHP [median 5.7; interquartile range (IQR), 1.4-12.0 micromol/mol creatinine] compared with the control group (3; 0.5-6.4 micromol/mol creatinine). In addition, the median levels (IQR) of 8-OHdG, BNMNs, and GST were markedly increased in the exposed [1.9 (1.4-15.4) micromol/mol creatinine; 6 (2-8) per thousand ; 22.1 (14.9-31.2) U/L, respectively] compared with controls [1.3 (1.0-4.0) micromol/mol creatinine, 2 (0-4) per thousand; and 13.1 (9.5-16.7) U/L, respectively]. These results appeared to be modified by smoking. However, multivariate logistic regression analysis revealed that exposure to COEs had the highest odds ratio among variables analyzed and that smoking was not a significant confounder of the levels of studied biomarkers. Overall, the present findings suggest that COE exposure led to increased internal PAH burden, genetic damage, oxidative stress, and GST activity. The consequences of the changes in these biomarkers, such as risk of cancer, warrant further investigations.