Peripheral Blood Lymphocytes Of Workers Research Articles

Absolute telomere length in peripheral blood lymphocytes of workers exposed to construction environment

ABSTRACT Construction environment is composed of various substances classified as carcinogens. Thus, workers exposed in this environment can be susceptible to genomic instability that can be evaluated by absolute telomere length (TL). In this work, we evaluated TL in construction workers compared to a non-exposed group performed by qPCR assay. The TL was evaluated in 59 men exposed to the construction environment (10 years of exposure) and 49 men non-exposed. Our data showed that individuals exposed to the construction environment exhibited a significantly lower TL in relation to non-exposed group (p = 0.009). Also, on the multiple linear regression model, we observed that TL was significantly influenced by the construction environment exposure (p ≤ 0.001). Additionally, the arsenic exposure is associated to a shortening telomere (p ≤ 0.001), and the lead exposure caused an increase in TL (p ≤ 0.001). Thus, our findings suggest a modulation in TL by construction environment exposure, mainly by arsenic and lead exposure.

Influence of occupational aluminum exposure on cognitive function and glutamate receptor protein expression in workers

Objective: To investigate the influence of occupational aluminum exposure on cognitive function and glutamate receptor protein expression in peripheral blood lymphocytes in workers and the possibility of glutamate receptor being used as a biomarker for cognitive impairment in aluminum workers. Methods: From October to December, 2014, cluster sampling was performed to select 121 workers in aluminum electrolysis workshop as exposure group and 231 workers in thermoelectric workshop and logistics department as control group. Mini-Mental State Examination, clock drawing test, digit span test (DST) , verbal fluency test (VFT) , and Fuld Object-Memory (FOM) Evaluation were used to analyze cognitive function. Graphite furnace atomic absorption spectrophotometry was used to measure plasma aluminum level as an exposure indicator. Enzyme-linked immunosorbent assay was used to measure the content of glutamate receptor proteins in peripheral blood lymphocytes, including the subunits of N-methyl-D-aspartate receptor NR1, NR2A, and NR2B and metabotropic glutamate receptor 1 (mGluR1) . The correlation between cognitive function indices and the content of glutamate receptor proteins was analyzed. Results: There was no significant difference in plasma aluminum level between the control group and the exposure group (132.52±80.40 μg/L vs 182.88±72.32 μg/L, P>0.05) . According to the plasma aluminum level, the study subjects were divided into control group and low-, medium-, and high-level plasma aluminum groups, and there were significant differences in plasma aluminum level between these groups (all P<0.01) . The high-level plasma aluminum group had a significantly lower memory ability score than the control group and the low- and medium-level plasma aluminum groups (all P<0.05) . The high-level plasma aluminum group had lower DST and digital span forward (DSF) scores than the control group and the low-and medium-level plasma aluminum groups. The low-, medium-, and high-level plasma aluminum groups had lower digital span backward (DSB) scores than the control group. The medium-and high-level plasma aluminum groups had lower VFT scores than the control group and the low-level plasma aluminum group. The high-level plasma aluminum group had significantly lower expression of NR1 and NR2A proteins than the control group and the low-and medium-level plasma aluminum groups, and the medium- and high-level plasma aluminum groups had significantly higher expression of mGluR1 protein than the control group and the low-level plasma aluminum group (all P<0.05) . The expression of NR1 and NR2A proteins was negatively correlated with plasma aluminum level (r=-0.475 and -0.692, both P<0.05) , andthe expression of mGluR1 protein was positively correlated with plasma aluminum level (r=0.756, P<0.05) . The expression of NR1 protein was positively correlated with DSF, DSB, DST, and VFT scores (r(s)=0.213, 0.249, 0.271, and 0.228, all P<0.05) , and the expression of NR2A protein was positively correlated with VFT score (r(s)=0.206, P<0.05) . Conclusion: Occupational aluminum exposure may affect workers' memory function, and the expression of NR1 and NR2A in peripheral blood lymphocytes is correlated with cognitive function indices and can be used as biomarkers for cognitive impairment in aluminum workers.

Assessment of DNA/Chromosome Damage in the Peripheral Blood Lymphocytes of Workers Exposed to Indium Compounds.

This study was conducted to investigate possible genotoxic effects resulting from occupational exposure to indium compounds. We performed a cytogenetic analysis of peripheral blood lymphocytes gathered from 57 individuals exposed to indium at an indium ingot production plant in Guangxi, China, and compared the results with those obtained from 63 control subjects. The lymphocytes from both groups were examined in the chromosomal aberrations (CAs) assay, cytokinesis-block micronucleus (CBMN) assay, and single-cell gel electrophoresis (comet) assay. Samples of personal breathing zone air were collected throughout the work shift of each subject. Blood and urine samples were collected before and after each work shift on the same day as the air samples were collected. Our assay results showed that workers in the indium production plant were exposed to significantly higher levels of indium (median exposure, 8.00 μg/m3) than the control subjects. Also, higher concentrations of urinary indium (U-In) were found in the exposed workers than the control subjects. When compared with the control subjects, the exposed workers showed higher levels of DNA damage as detected by the comet assay (tail length and TDNA%), significantly higher frequencies of CAs/100 cells, and increased CBMN frequencies. Moreover, the mean CBMN frequency in the non-smokers exposed to indium was significantly higher than that in the non-smoker control subjects (3.14‰ vs 1.00‰, respectively; P < .01). U-In levels, comet assay, CBMN, and CA test proved to be the most sensitive biological markers for detecting occupational exposure to indium compounds and can also be used to assess the health risks of the exposed workers.

A association of genetic polymorphisms of XRCC1 and damage levels in workers exposed to coal tar pitch

Objective: To study the relationship between XRCC1 gene polymorphism and DNA damage in peripheral blood lymphocytes of workers exposed to coal tar pitch. Methods: 203 coal tar asphalt device operation area workers (exposure group) and 76 logistics management personnel (control group) as the research ob-ject, determination of 1-hydroxypyrene concentrations in the urine as polycyclic aromatic hydrocarbons expo-sure dose, using the alkaline comet assay evaluation a peripheral blood lymphocyte DNA damage degree, using TaqMan MGB real time PCR method to detect XRCC1 gene 3 loci (XRCC1-194, XRCC1-280 and XRCC1-399) single nucleotide polymorphism. Results: No significant differences was observed in age, sex, smoking and alco-hol consumption between the two groups (P>0.05). The level of 1-OHP in the exposed group was significantly higher than that in the control group (1.27±0.93 μg/g creatinine) (P<0.05). The comet Olive tail moment level (3.21±0.93) in the peripheral blood lymphocytes of the exposed group was significantly higher than that in the control group (0.94 ± 0.39) (P<0.05). There was no significant difference in genotype distribution of XRCC1-194, XRCC1-280 and XRCC1-399 between the two groups (P>0.05). There was a significant correlation be-tween the XRCC1-280 locus gene polymorphism and comet Olive tail moment in the exposure group (P<0.05) af-ter adjustment for sex, age, smoking rate, drinking rate, length of service and urinary 1-OHP concentration. The comet Olive tail moment level of GG individuals carrying wild homozygous genotype was significantly lower than that of individuals carrying heterozygous genotype GA and carrying mutant homozygous genotype AA (P< 0.05) , and the difference was statistically significant (P<0.05) The comet Olive tail moment level of heterozy-gous genotype GA was significantly lower than that of genotype AA with mutational homozygous genotype AA (P<0.05) , and the difference was statistically significant (P<0.05). Conclusion: Arg280His locus polymor-phism of XRCC1 gene may influence the DNA damage level of peripheral blood lymphocytes induced by occupational exposure to coal tar pitch.

Cytogenetic Analysis of Peripheral Blood Lymphocytes of Workers Occupationally Exposed to Benzene in A Fuel Station in Erbil City- Iraq

The objective of the present study was to evaluate genotoxic effects in petrol station workers, who were previously exposed occupationally to benzene in comparison with a selected control group, through inhalation and skin contamination, by using the cytokinesis- blocked micronucleus (CBMN) and chromosomal aberration tests carried on peripheral blood lymphocytes. The study included (35) male petrol station worker and 25 control subjects. Metaphase chromosome preparations were analyzed, chromosome aberrations in peripheral blood lymphocytes, were examined. The results showed that the frequency of cell with aberrations in exposed workers was significantly higher (P≤0.01) than that of control subjects. Most chromosome aberration found in exposed group was acentric fragment, chromosome break, dicentric. Furtheremore, also the frequency of micronucle( MN) was highly significant in benzyne exposed groups as compared with control person (P≤0.01). In conclusion significant excess of chromosomal aberrations in workers who exposed occupationally to benzene, where compare to the matched controls.

Chromosome aberration and micronucleus frequency in peripheral blood lymphocytes in radiation workers

To investigate chromosome aberration and micronucleus frequency in peripheral blood lymphocytes in workers engaged in radiation for a long time, to reduce occupational hazard caused by ionizing radiation, and to further strengthen health surveillance. A total of 366 members of medical staff engaged in radiation work who underwent physical examinations in Hangzhou Hospital of Prevention and Treatment of Occupation Diseases from 2014 to 2015 were enrolled as radiation group, consisting of staff engaged in X-ray diagnosis, diagnostic radiology, radiotherapy, and interventional radiology. Another 100 members of medical staff without exposure to radiation were enrolled as control group. Whole blood culture was used to measure chromosome aberration and micronucleus frequency in peripheral blood lymphocytes. The radiation group had a significantly higher rate of chromosome aberration than the control group (0.30% vs 0.09% , χ(2)= 13.43, P<0.01), as well as a significantly higher micronucleus frequency than the control group (2.09‰ vs 0.08‰, χ(2)=74.4, P<0.01). The abnormal rates of chromosome aberration and micronucleus showed no significant differences across radiation workers with different working years (P>0.05). The staff engaged in X-ray diagnosis, diagnostic radiology, radiotherapy, and interventional radiology had rates of chromosome aberration of 0.25%, 0.25%, 0.23%, and 0.41%, respectively, which showed a significant difference between the staff at these four posts (χ(2)=8.22, P<0.05); the micronucleus frequencies in the staff at these four posts were 1.36‰, 1.28‰, 1.14‰, and 3.79‰, respectively, and showed a significant difference between the staff at these four posts (χ(2)=251.09, P<0.01). Radiation workers are exposed to lowdose ionizing radiation for a long time, which may cause significant increases in the rate of chromosome aberration and micronucleus frequency in peripheral blood lymphocytes.

Chromosome aberrations determined by sFISH and G-banding in lymphocytes from workers with internal deposits of plutonium

Purpose: To examine the influence of α-particle radiation exposure from internally deposited plutonium on chromosome aberration frequencies in peripheral blood lymphocytes of workers from the Sellafield nuclear facility, UK. Materials and methods: Chromosome aberration data from historical single colour fluorescence in situ hybridization (sFISH) and Giemsa banding (G-banding) analyses, together with more recent sFISH results, were assessed using common aberration analysis criteria and revised radiation dosimetry. The combined sFISH group comprised 29 men with a mean internal red bone marrow dose of 21.0 mGy and a mean external γ-ray dose of 541 mGy. The G-banding group comprised 23 men with a mean internal red bone marrow dose of 23.0 mGy and a mean external γ-ray dose of 315 mGy. Results: Observed translocation frequencies corresponded to expectations based on age and external γ-ray dose with no need to postulate a contribution from α-particle irradiation of the red bone marrow by internally deposited plutonium. Frequencies of stable cells with complex aberrations, including insertions, were similar to those in a group of controls and a group of workers with external radiation exposure only, who were studied concurrently. In a similar comparison there is some suggestion of an increase in cells with unstable complex aberrations and this may reflect recent direct exposure to circulating lymphocytes. Conclusions: Reference to in vitro dose response data for the induction of stable aberrant cells by α-particle irradiation indicates that the low red bone marrow α-particle radiation doses received by the Sellafield workers would not result in a discernible increase in translocations, thus supporting the in vivo findings. Therefore, the greater risk from occupational radiation exposure of the bone marrow resulting in viable chromosomally aberrant cells comes from, in general, much larger γ-ray exposure in comparison to α-particle exposure from plutonium.

Changes in mRNA expression of p53 and related downstream genes in peripheral blood lymphocytes in workers occupationally exposed to arsenic

To investigate the changes in mRNA expression of p53 and related downstream genes in peripheral blood lymphocytes in workers occupationally exposed to arsenic as well as its influencing factors, and to analyze the mechanism of genetic toxicity of arsenic. With cluster random sampling, 79 workers from an arsenic smelting plant were selected as exposure group, and another 24 people without occupational exposure to arsenic were selected as control group. The relative mRNA expression of p53 and related downstream genes in the peripheral blood lymphocytes of the two groups was determined by quantitative realtime PCR. The levels of inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in urine were determined by hydride generation-atomic absorption spectrometry. The exposure group had significantly higher levels of iAs, MMA, and DMA than the control group (P<0.01); the exposure group had significantly higher relative mRNA expression (2(-ΔΔCt)) of p53 and four related downstream genes in peripheral blood lymphocytes than the control group (P<0.05); the relative mRNA expression of p53 and related downstream genes was positively correlated with each other (P<0.01), with a correlation coefficient greater than 0.4; the levels of arsenic compounds in urine were positively correlated with the relative mRNA expression of p53 and some of its downstream genes (P<0.05). The changes in mRNA expression of p53 and related downstream genes are closely related to the metabolic transformation of inorganic arsenic in workers occupationally exposed to arsenic, and it also plays an important role in genetic toxicity and carcinogenic effect in people exposed to arsenic.

The 3-OH Derivative of the Polychlorinated Biphenyl (PCB)-28 Inhibits Telomerase Expression and Accelerates Telomere Shortening in Vitro: A Rationale for the Significantly Shortened Telomere Length Found in Peripheral Blood Lymphocytes of Workers Exposed to High Doses of Lower Chlorinated PCBs

Polychlorinated biphenyls (PCBs) are technical mixtures with a varying three-dimensional structure, depending on the degree and the position of the chlorine atom on two benzene rings. The International Agency for Research on Cancer (IARC) classified PCBs as possible carcinogens. In Germany, the employees of a transformer recycling company were contaminated with high blood levels of PCBs. Within the HELPcB-program (Health Effects in High-level Exposure to PCB), the telomere lengths (TL) of peripheral blood granulocytes and lymphocytes of 208 exposed workers were measured using flow-cytometry-based in situ hybridization (flow-FISH). Whereas the mean age-adjusted TL within granulocytes was not affected, the TL within lymphocytes of PCB exposed individuals was significantly shortened, compared to normal individuals (µ = -0,77kb; p<0.0001). Significantly shortened TL in lymphocytes was associated with a high body burden of lower chlorinated PCBs but not of dioxin-like PCBs or higher chlorinated PCBs (PCB 28 (KK – 0.140, p=0.045), PCB 52 (KK – 0.184, p=0.008), PCB 101 (KK – 0.150, p=0.003)). As PCB28 represented the most sensitive indicator of additional PCB contamination within the group of PCB exposed workers, we chose PCB28 to directly test the effects of lower chlorinated PCBs on telomere shortening in vitro. We first applied a structure-based design approach to develop 3OH-PCB28, a potential bioactive derivative of PCB28. Biotransformation of PCB28 by HePG2 liver cells confirmed the formation of 3OH-PCB28, and 3OH-PCB28 showed dose-dependent, significant antiproliferative and proapoptotic effects on K562 cells as well as on stimulated T-cells from healthy blood donors. In addition, when T-cell proliferation was stimulated by phytohemagglutinin (PHA), tetanus toxoid (TT), or cytomegalovirus (CMV) antigen, the upregulation of telomerase expression was inhibited by 3OH-PCB28 at subtoxic concentrations. As telomerase expression levels determine the lifespan of T-cells, these results suggest that 3OH-PCB28 might affect T- cell capacity for cell division and clonal expansion. Furthermore, 3OH-PCB28 inhibited telomerase expression in K562 cells and led to significantly shorter telomeres, compared to controls, in long-term incubation experiments. We therefore provide mechanistic evidence for the shortened TL found in the lymphocytes of workers contaminated with lower chlorinated PCBs. As short TL in peripheral blood cells have been shown to be associated with increased risk for cancer, long-time monitoring of PCB exposed workers might provide further insights into the abovementioned functional correlations. DisclosuresBrümmendorf:Novartis: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Patents & Royalties, Research Funding.

Genetic and oxidative damage of peripheral blood lymphocytes in workers with occupational exposure to coal

Coal is an important fossil fuel used to generate energy. Coal dust is constituted primarily of hydrocarbons and metals. During coal extraction, large quantities of coal dust particles are emitted, contributing to environmental pollution. Coal miners are constantly exposed to coal dust and its derivatives. The goal of this study was to evaluate the potential genotoxic effects of coal and oxidative stress in individuals from Candiota who were exposed to coal as part of their occupation. The comet assay and micronucleus (MN) test were used to assess these effects. This study involved 128 male participants of whom 71 reported work that included exposure to coal (exposed group) and 57 reported working at different jobs (unexposed group). The exposed group had a significantly increased damage index and damage frequency, as assessed using the comet assay, and increased MN and nucleoplasmic bridge frequencies, as assessed using the MN assay, compared with unexposed individuals. Significant and positive correlations between MN frequencies in the lymphocytes and buccal cells of control and exposed individuals were observed. The exposed individuals presented lower average levels of thiobarbituric acid reactive substances (TBARS) and catalase activity (CAT), while the mean superoxide dismutase activity (SOD) levels were higher in this group. The exposed group also had higher hematocrit levels. No correlation between DNA damage and inorganic elements, as identified using PIXE, was found; however, there was a correlation between the damage index and zinc. The evidence that exposure to coal and its derivatives presents a genetic hazard demonstrates the need for protective measures and educational programs for coal miners.

A Comprehensive Analysis of Plausible Genotoxic Covariates Among Workers of a Polyvinyl Chloride Plant Exposed to Vinyl Chloride Monomer

The aim of this study was to assess the frequency of chromosomal aberrations-including chromatid type aberrations (CTAs), chromosomal type aberrations, micronucleus (MN) comet assay, and XRCC1 399 Arg/Gln polymorphism-in peripheral blood lymphocytes of workers occupationally exposed to vinyl chloride monomer (VCM). A total of 52 workers and an equal number of controls were recruited into the study to explore the potential cytogenetic risk of occupational exposure to VCM. Questionnaires were administered to obtain details of habitual cigarette-smoking, alcohol-consumption pattern, and occupation, etc. The exposed subjects and controls were classified into two groups based on age (group I <40 years; group II ≥40 years), and exposed subjects were further classified based on exposure duration (>8 and ≥8 years). CTA, MN, and comet assay frequency were significantly greater in polyvinyl chloride (PVC) factory workers (p < 0.05) with long-duration work. CTA, MN, and comet assay values were found to be increased with age in exposed subjects as well as in controls, with exposed subjects showing a statistically greater degree. An extensively greater MN frequency was observed in smokers exposed to VCM than in the control group (P < 0.05). The mean tail length of exposed subjects was greater compared with controls. The study on XRCC1 399 Arg/gln polymorphism in PVC factory workers showed less significant difference in allele frequency compared with controls. In conclusion, this results of work provides evidence for an apparent genotoxic effect associated with VCM exposure. Our results reinforce the greater sensitivity of cytogenetic assays for biomonitoring of occupationally exposed populations. Statistics indicate that workers exposed to VCM are at carcinogenic risk and should be monitored for long-term adverse effects from their exposure.

Biomonitoring of rural workers exposed to a complex mixture of pesticides in the municipalities of Tianguá and Ubajara (Ceará state, Brazil): Genotoxic and cytogenetic studies

In recent years, the use of pesticides in agriculture has been steadily increasing, and associations between exposure to agricultural chemicals and DNA damage and cancer have been reported. Brazil is one of the world leaders in pesticide use; however, studies that evaluate the impact of pesticide exposure on cancer incidence and mortality are very scarce in the Brazilian population. The alkaline comet assay and the chromosome aberration (CA) test were used to evaluate primary DNA damage in the peripheral blood lymphocytes of workers exposed to a complex mixture of pesticides in two small rural communities in the municipalities of Tianguá and Ubajara, located in the western part of Ceará State (Northeast Brazil), which are among the largest agricultural areas of the state. The comet assay showed that the damage index and damage frequency observed in the exposed groups were significantly higher in relation to the controls (P < 0.05). On the other hand, no differences were detected regarding structural and numerical CAs in the communities evaluated. Additionally, the observed levels of DNA strand breaks and frequencies of CAs, stratified for exposure time, were not statistically different for individuals of either rural community. Our results suggest that the damages caused by pesticides in our study area were not great enough to induce permanent mutations or to interfere with mitotic apparatus formation; minimal pesticide damages could have undergone cellular repair, explaining the absence of structural and numerical CAs.

Cytokinesis-blocked micronucleus cytome and comet assays in peripheral blood lymphocytes of workers exposed to lead considering folate and vitamin B12 status

In human biomonitoring, factors such as age, gender, smoking habit and alcohol consumption are usually considered and identified as agents that exert an impact on genotoxicity biomarkers. However, as a rule, factors like micronutrient status are not considered in biomonitoring studies. This paper reports on genotoxic damage in Pb-exposed workers using data obtained from the cytokinesis-block micronucleus (CBMN) cytome assay and alkaline comet assay with silver staining, considering folate and vitamin B12 nutritional status. Analysis of the results showed that the Pb-exposed group presented a 24-fold higher Pb content in the blood compared to controls. The Pb-exposed workers presented significantly greater micronuclei (MNi) counts (Z=7.9583; p<0.0001) and DNA damage, assessed by the comet assay (DF: Z=7.7056; p<0.0001 and DI: Z=7.4749; p<0.0001), but no correlation with Pb blood concentrations were detected. These two groups did not differ significantly concerning folate and vitamin B12 levels. Regarding folate, it is possible that this similarity is associated with folic acid flour-enrichment, introduced in Brazil in 2004 to prevent neural tube defects. The mean folate level obtained in the Pb-exposed group was 6.18ng/ml. The subgroup of individuals with serum folate levels equal to or higher than the mean presented significantly higher MNi (Z=2.3776; p=0.017) and nucleoplasmic bridge (NPB) frequencies (Z=1.9850; p=0.047) in peripheral blood lymphocytes. A significant positive correlation was observed between the age of Pb-exposed workers and MNi frequencies (Γ=0.3328; p<0.001), NPBs (Γ=0.1832; p<0.042) and DNA damage assessed by the comet assay (DF: Γ=0.1764; p=0.035 and DI: Γ=0.11852; p=0.028). These findings suggest that high folate levels alone do not guarantee protection against genotoxic damage. Moreover, folic acid supplementation should be studied using more efficient approaches to determine safe amounts and potential deleterious effects.

Shorter telomere length in peripheral blood lymphocytes of workers exposed to polycyclic aromatic hydrocarbons

Shorter telomere length (TL) in peripheral blood lymphocytes (PBLs) is predictive of lung cancer risk. Polycyclic aromatic hydrocarbons (PAHs) are established lung carcinogens that cause chromosome instability. Whether PAH exposure and its molecular effects are linked with shorter TL has never been evaluated. In the present study, we investigated the effect of chronic exposure to PAHs on TL measured in PBLs of Polish male non-current smoking cokeoven workers and matched controls. PAH exposure and molecular effects were characterized using measures of internal dose (urinary 1-pyrenol), effective dose [anti-benzo[a]pyrene diolepoxide (anti-BPDE)-DNA adduct], genetic instability (micronuclei, MN) and DNA methylation [p53 promoter and Alu and long interspersed nuclear element-1 (LINE-1) repetitive elements, as surrogate measures of global methylation] in PBLs. TL was measured by real-time polymerase chain reaction. Cokeoven workers were heavily exposed to PAHs (79% exceeded the urinary 1-pyrenol biological exposure index) and exhibited lower TL (P = 0.038) than controls, as well as higher levels of genetic and chromosomal alterations [i.e. anti-BPDE-DNA adduct and MN (P < 0.0001)] and epigenetic changes [i.e. p53 gene-specific promoter and global methylation (P <or= 0.001)]. TL decreased with longer duration of work as cokeoven worker (P = 0.039) and in all subjects with higher levels of anti-BPDE-DNA adduct (P = 0.042), p53 hypomethylation (P = 0.005) and MN (P = 0.009). In multivariate analysis, years of work in cokery (P = 0.008) and p53 hypomethylation (P = 0.001) were the principal determinants of shorter TL. Our results indicate that shorter TL is associated with chronic PAH exposure. The interrelations with other genetic and epigenetic mechanisms in our data suggest that shorter TL could be a central event in PAH carcinogenesis.

MRNA expression levels of p53 and DNA damage and repair genes in peripheral blood lymphocytes of benzene-exposed workers

To investigate the relationship between the mRNA expression levels of p53-mediating DNA damage and repair genes in the peripheral blood lymphocytes of workers and their exposures to benzene in their working environment. The mRNA expression levels of p53 and related genes were determined by SYBR Green I chimeric fluorescence quantitative real-time RT-PCR analysis in peripheral blood lymphocytes of 72 workers, who were classified into group A (46 direct exposure to benzene) and group B (26 indirect exposure to benzene) based on their positions, and 29 controls. The differences of gene expression levels were analyzed by software REST 2005. Meanwhile, the peripheral blood leukocytes, hemoglobin and platelet of workers and controls were counted. Benzene content was measured in the samples of toluene, used as raw material, and spraying agents and benzene, toluene and xylene concentrations in the air of workplaces were monitored. There were no significant differences in the mRNA expression levels of p53, Ku80, Ape1 and Mdm-2 between group A or group B and control group (P > 0.05). The expression up-regulation of p21 mRNA was found, but without significant difference (P > 0.05). However, the mRNA expression levels of Rad51, Bcl-2, Bax, Xpa and Xpc in group A and Rad51 in group B were downregulated significantly (P < 0.05 or P < 0.01). Moreover, both the counts of white blood cell, hemoglobin and platelet in group A were (4.93 +/- 1.27) x 10(9)/L, (123.97 +/- 11.80) g/L and (124.02 +/- 41.22) x 10(9)/L respectively and platelet in group B (135.80 +/- 39.44) x 10(9)/L were significantly lower than in control group (P < 0.05 or P < 0.01). The mRNA expression levels of some p53-mediating DNA damage and repair genes are downregulated in the workers chronically exposed to low benzene concentration. The working environment impacts on health of group A workers are greater than the ones of group B.

Micronuclei in peripheral blood lymphocytes of workers exposed to lead

Lead plays an important role in many industrial processes. Although highly useful to man, lead has various types of toxic effects. There is constantly growing evidence of a relationship between the induction of chromosome breaks and an increased risk of onset of cancer. However, available data about the possible genotoxic and carcinogenic action of lead are conflicting. In this report we present the results of studies on lead concentrations in blood and the respective micronucleus frequencies in peripheral blood lymphocytes from workers employed in the recycling of automotive batteries in the surroundings of Porto Alegre, Brazil. We observed that in the occupationally exposed group, both lead concentration in peripheral blood and micronucleus frequency in lymphocytes were significantly higher compared to control ( Z = 6.35, P < 0.0001 and Z = 4.47, P < 0.0001). The nuclear division index (NDI) values were significantly higher in the control group than in the exposed group ( Z = 2.13, P = 0.0330), indicating a possible effect of Pb on nuclear proliferation. We also detected a negative correlation between micronuclei and progression of nuclear division ( τ = −0.312, P = 0.0129). There were no changes in micronucleus frequency between smoking and non-smoking workers exposed to lead ( Z = 0.03, P = 0.9790). The only difference found between the groups of smokers and non-smokers was with respect to NDI, whose values were significantly higher among non-smokers ( Z = 1.98, P = 0.0481).

DNA–protein crosslinks and p53 protein expression in relation to occupational exposure to formaldehyde

Background: Formaldehyde (FA) is classified as a probable human carcinogen. Aims: To examine DNA protein crosslinks (DPC) and p53, which are generally known to be involved in carcinogenesis, in peripheral...

Relationship between HSP70 level and genotoxic damage in peripheral blood lymphocytes of workers exposed to coke oven emissions

Objective To explore the relationship between HSP70 level and the degree of DNA damage in lymphocytes of workers exposed to coke oven emissions. Methods Level of HSP70 in peripheral blood lymphocytes was measured by Western blot,and the degree of DNA damage was detected by micronucleus and Comet Assay. Results Compared with the control group,HSP70 levels in the exposed group increased(1?960±536 vs . 1?712 ±442, P 0.05),and micronucleus rate(5?162/10 6±2?205/10 6 vs .2?362/10 6±1?241/10 6) and DNA damage score(67?000/10 6±64?934/10 6 vs .28?936/10 6±30?874/10 6) also increased significantly.However,in the exposed group,the levels of HSP70 had strong negative correlation with micronucleus rates( r =-0.461, P 0.01) and DNA damage scores( r = -0.663, P 0.01). Conclusion The increase of HSP70 level may be involved in protection of DNA from genotoxic damage induced by carcinogen.

Evaluation of DNA damage in workers occupationally exposed to pesticides using single-cell gel electrophoresis (SCGE) assay: Pesticide genotoxicity revealed by comet assay

The comet assay, also called the single-cell gel electrophoresis (SCGE) assay, is a rapid and sensitive method for the detection of DNA damage (strand breaks and alkali-labile sites) in individual cells. The assay is based on the embedding of cells in agarose, their lysis in alkaline buffer and finally subjection to an electric current. In the present study, alkaline SCGE was used to evaluate the extent of primary DNA damage and DNA repair in peripheral blood lymphocytes of workers employed in pesticide production. After the period of high pesticide exposure, lymphocytes of the occupationally exposed workers manifested increased tail length and tail moment compared to the control group. After the workers spent 6 months out of the pesticide exposure zone, both endpoints were still above that of the control but significantly decreased as compared to the results of the first analysis.

Biological monitoring of bidi industry workers occupationally exposed to tobacco

Ambient and biological monitoring was undertaken among tobacco processors who are chronically exposed to tobacco particulates via nasopharyngeal and cutaneous routes. Ambient monitoring revealed that the inspirable dust concentration was 150-fold higher in the tobacco factory than in the control environment, and was associated with chronic bronchitis in workers. Increased systemic exposure to tobacco constituents was evident from the high levels of cotinine, thioethers, promutagens and direct acting mutagens in workers’ urine. The mean glutathione level and glutathione S-transferase activity were significantly lower in the peripheral blood lymphocytes of workers; however, the frequency of the GSTM1 null allele was similar to that in controls. A significant increase in chromosomal damage was noted in target and non-target cells of tobacco processors. In view of the association between tobacco use and several non-communicable diseases, the findings of the present study indicate an urgent need to minimize tobacco exposure among the processors.