Level Of Chromosome Damage Research Articles

Risks for human health related to the presence of grayanotoxins in certain honey.

The European Commission asked EFSA for a scientific opinion on the risks for human health of the presence of grayanotoxins (GTXs) in 'certain honey' from Ericaceae plants. The risk assessment included all structurally related grayananes occurring with GTXs in 'certain' honey. Oral exposure is associated with acute intoxication in humans. Acute symptoms affect the muscles, nervous and cardiovascular systems. These may lead to complete atrioventricular block, convulsions, mental confusion, agitation, syncope and respiratory depression. For acute effects, the CONTAM Panel derived a reference point (RP) of 15.3μg/kg body weight for the sum of GTX I and III based on a BMDL10 for reduced heart rate in rats. A similar relative potency was considered for GTX I. Without chronic toxicity studies, an RP for long-term effects could not be derived. There is evidence for genotoxicity in mice exposed to GTX III or honey containing GTX I and III, showing increased levels of chromosomal damage. The mechanism of genotoxicity is unknown. Without representative occurrence data for the sum of GTX I and III and consumption data from Ericaceae honey, acute dietary exposure was estimated based on selected concentrations for GTX I and III reflecting concentrations measured in 'certain' honeys. Applying a margin of exposure (MOE) approach, the estimated MOEs raised health concerns for acute toxicity. The Panel calculated the highest concentrations for GTX I and III below which no acute effects would be expected following 'certain honey' consumption. The Panel is 75% or more certain that the calculated highest concentration of 0.05mg for the sum of GTX I and III per kg honey is protective for all age groups regarding acute intoxications. This value does not consider other grayananes in 'certain honey' and does not cover the identified genotoxicity.

HBM4EU Chromates Study-Genotoxicity and Oxidative Stress Biomarkers in Workers Exposed to Hexavalent Chromium.

A study was conducted within the European Human Biomonitoring Initiative (HBM4EU) to characterize occupational exposure to Cr(VI). Herein we present the results of biomarkers of genotoxicity and oxidative stress, including micronucleus analysis in lymphocytes and reticulocytes, the comet assay in whole blood, and malondialdehyde and 8-oxo-2′-deoxyguanosine in urine. Workers from several Cr(VI)-related industrial activities and controls from industrial (within company) and non-industrial (outwith company) environments were included. The significantly increased genotoxicity (p = 0.03 for MN in lymphocytes and reticulocytes; p < 0.001 for comet assay data) and oxidative stress levels (p = 0.007 and p < 0.001 for MDA and 8-OHdG levels in pre-shift urine samples, respectively) that were detected in the exposed workers over the outwith company controls suggest that Cr(VI) exposure might still represent a health risk, particularly, for chrome painters and electrolytic bath platers, despite the low Cr exposure. The within-company controls displayed DNA and chromosomal damage levels that were comparable to those of the exposed group, highlighting the relevance of considering all industry workers as potentially exposed. The use of effect biomarkers proved their capacity to detect the early biological effects from low Cr(VI) exposure, and to contribute to identifying subgroups that are at higher risk. Overall, this study reinforces the need for further re-evaluation of the occupational exposure limit and better application of protection measures. However, it also raised some additional questions and unexplained inconsistencies that need follow-up studies to be clarified.

Features of cytogenetic effects in oncological patients during radiotherapy with prior radiation exposure

Background. Radiotherapy can be used numerous times for treating oncological patients as one of the most effective ways of fighting against cancer. However, there is limited data on the effect of prior radiation exposure on the further development of cytogenetic alterations under the influence of radiological factors. Primary radiation treatment, as well as the second one, is an example of a complex scenario of fractionated irradiation, examination of which is of fundamental and practical importance for understanding complex processes of formation and elimination of cytogenetic markers of radiation exposure for further improvement of biodosimetry system and development of personalised radiotherapy. Purpose. To determine the nature of changes of radiation-induced cytogenetic alterations and genomic disorders in patients with lung, head and neck cancer during radiotherapy on the background of prior radiation exposure. during radiotherapy with prior radiation exposure. Materials and methods. 29 oncological patients with lung, head and neck cancer were examined. 16 of them received radiotherapy for the first time, and 13 – for the second. We studied chromosome aberration frequency and genomic disorders during external beam radiation therapy by cytogenetic test. Results. In the patients pre-irradiation level of cytogenetic injuries exceeded spontaneous level. In addition, chromosome aberration frequency in the patients, who had received prior radiation exposure, was significantly higher than those who had not been treated with radiotherapy. It depended on the period between radiotherapy treatment courses. The increase in level of radiation-induced cytogenetic injuries during the whole radiotherapy treatment course of patients was observed, regardless of prior therapeutic exposure. Under quite a high level of chromosome damage in the group of secondary patients at the beginning of the treatment, chromosome aberration increase rates were higher than in the group of the primary patients. The distribution of markers of radiation exposure over cells during radiotherapy was overdispersed according to Poisson statistics in both of the groups. The changes in the frequency of genomic disorders were mostly of fluctuating nature. Conclusions. In the secondary patients, the level of cytogenetic indexes before radiotherapy exceeded the indexes of the primary patients. The level of chromosome damage increased during the radiotherapy treatment course in both primary and secondary patients, but at different rates. The additional genotoxic effect of reirradiation manifested itself only in a greater maximum quantity of aberrations per aberrant cell in the secondary patients. In terms of increased rates of cytogenetic injuries, a more significant genotoxic effect from the second radiotherapy on the background of prior radiation exposure was not detected.

The Effects of Combined Physical Exercise on Serum Redox Biomarkers and Leukocyte DNA Damage of Obese Women.

Obesity is usually linked to oxidative stress, which can lead to damage to biomolecules. The combination of aerobic and strength exercises seems to induce health benefits in obese individuals, but little is known about the effects of combined physical exercise on redox homeostasis and DNA damage in this population. Thus, the aim of the current study was to determine the effects of 16 weeks of combined physical exercise on biomarkers of oxidative stress and DNA damage in obese women. 17 obese women underwent 16 weeks of a combined physical training program, 3 times per week. Anthropometric and biochemical parameters, serum superoxide dismutase (SOD) and glutathione peroxidase activity, plasma 8-isoprostane levels, and DNA and chromosomal damage were evaluated before and after physical training. Combined physical exercise training decreased body weight (83.2 ± 9.6 vs. 80.2 ± 9.6 kg), body mass index (33.8 ± 3.6 vs. 32.6 ± 3.7 kg·m−2), body fat (40.2 ± 2.6 vs. 39.0 ± 3.2%), and waist circumference (99.3 ± 9.4 vs. 94.1 ± 8.8 cm), while the fat-free mass was augmented (59.9 ± 2.9 vs. 60.7 ± 3.1 kg). Moreover, blood glucose reduced (113.5 ± 29.6 vs. 107.3 ± 28.9 mg/dL) along with high-density lipoprotein (54.6 ± 18.1 vs. 59.0 ± 18.8 mg/dL), TSH (2.1 ± 1.1 vs. 2.6 ± 1.2 mIU/mL), and free T4 (0.9 ± 0.1 vs. 1.12 ± 0.2 ng/dL) increase after physical exercise training. Plasma 8-isoprostane levels (17.24 ± 7.9 vs. 29.11 ± 17.44 pg/mL) and DNA damage (34.16 ± 7.1 vs. 45.96 ± 5.8% DNA in tail) were also higher after physical training. No changes were observed in chromosomal damage levels. These results suggest that 16 weeks of combined exercise training 3 times per week is effective in reducing body fat but also increases oxidative stress and DNA damage in obese women.

Genomic Instability in Exfoliated Buccal Cells among Cement Warehouse Workers.

Background: Workers in cement warehouses of Kerala are enduring long-standing exposure to cement dust, which is considered genotoxic. Objective: To evaluate the extent of genotoxicity and cytotoxicity caused due to exposure of cement dust among those working in cement warehouses. Methods: The study included 82 cement warehouse workers and 82 age-matched individuals with no exposure to cement dust. Exfoliated buccal micronucleus cytome assay (BMCyt) was performed to analyze the genotoxic and cytotoxic effects caused by inhalation of cement dust. Results: The frequency of various genotoxic and cytotoxic end markers (micronucleated cells [2-fold increase, p<0.001], nuclear buds [4-fold increase, p<0.001], binucleated cells [4-fold increase, p<0.001], karyorrhectic cells [2-fold increase, p<0.001], pyknotic cells [3- fold increase, p<0.001], and karyolytic cells [2-fold increase, p<0.001]) were higher in the exposed workers compared with unexposed group. Increase of these parameters represented an increased level of chromosomal damage, nuclear disintegration and increased cell death among exposed group compared with unexposed group. Conclusion: Continuous exposure to cement dust results in increased frequency of nuclear aberrations and cellular apoptosis. This may lead to defects in genome maintenance, accelerated ageing, increased chance of oral cancer and neurodegenerative disorders in those occupationally exposed to cement dust.

Different chromosome damage in lymphocytes of newly diagnosed gastrointestinal and breast cancer patients.

Structural chromosome aberrations are a predictive biomarker of cancer risk. Conventional chromosome analysis widely used for these purposes detects unstable chromosome aberrations that are eliminated during cell division. Stable aberrations that may persist in the body and tend to accumulate during a lifetime can be detected by fluorescence in situ hybridization (FISH). The aim of the study was to investigate the level of chromosome damage in newly diagnosed cancer patients and control subjects by FISH. Both groups of untreated cancer patients had increased frequency of aberrant cells. However, chromosome damage affected different cytogenetic endpoints. Stable translocations and cells with complex rearrangements were elevated in breast cancer patients whereas unstable chromosome aberrations (dicentric chromosomes and acentric fragments) were elevated in gastrointestinal cancer patients. These associations observed in nonsmokers were typically not pronounced in smokers (with the exception of dicentric chromosomes in gastrointestinal patients). Exposure to tobacco smoke increased aberrations in healthy controls but not in the cancer patients. Our study suggests an association between cancer and stable chromosomal rearrangements in breast cancer patients. Unstable aberrations elevated in gastrointestinal cancer patients may be at least partly ascribed to the exposure to diagnostic X-rays.

Production of mouse fetuses using spermatozoa exposed temporarily to high temperature or continuously to room temperature after freeze-drying in Na+-free/K+-rich EGTA buffer

Present study aimed to determine to what extent freeze-dried spermatozoa were able to withstand high-temperature conditions: transient increase in storage temperature and long-term exposure to room temperature. Mouse spermatozoa were freeze-dried in EGTA/Tris-HCl buffered solution alkalinized using KOH (K-ETBS, pH 7.7), and then stored for up to 7 months at 4 °C or 25 °C. After 2 months’ storage, some of the 4°C-stored spermatozoa were exposed to 40 °C for 1 week or 1 month, then again stored at 4 °C for the remaining storage period. Following storage, rehydrated spermatozoa were injected into mouse oocytes. The resulting zygotes were assessed for chromosome damage, in vitro development up to the blastocyst stage, and post-implantation development to normal fetuses on day 18 of gestation. In storage at 4 °C, one-week exposure to 40 °C had no adverse effect on the chromosome integrity and developmental competence compared to non-exposure to 40 °C (continuous storage at 4 °C). In contrast, one-month exposure to 40 °C caused an increasing level of chromosome damage (36%, P < 0.05) and reduced frequencies of blastocysts (54%, P < 0.05) and normal fetuses (36%, P < 0.05) compared to the frequencies obtained by continuous storage at 4 °C (15%, 82% and 52%, respectively). Storage at 25 °C resulted in accumulation of chromosome damage (27%, P < 0.05), leading to decreased blastocyst formation (63%, P < 0.05). But, the frequency of normal fetus (44%) was not significantly different from that obtained by continuous storage at 4 °C. Consequently, mouse spermatozoa freeze-dried in K-ETBS withstood temporary exposure to 40 °C for 1 week. Chromosome damage accumulated in spermatozoa during storage at 25 °C.

Association of BER and NER pathway polymorphism haplotypes and micronucleus frequencies with global DNA methylation in benzene-exposed workers of China: Effects of DNA repair genes polymorphisms on genetic damage

ObjectiveThe base excision repair (BER) pathway and nucleotide excision repair (NER) pathway play important roles in the repair of benzene-induced genetic damage, and the effects of polymorphisms in these pathways on genetic damage and global DNA methylation are of great interest. MethodsTen single nucleotide polymorphisms (SNPs) in the BER (XRCC1: rs25489, rs25487; APE1: rs1130409) and NER pathways (XPA: rs1800975; XPC: rs2228000, rs2228002; XPD: rs13181, rs1799793; XPG: rs17655; ERCC1: rs3212986) were analyzed by a Kompetitive allele-specific PCR (KASP) assay to find associations with cytokinesis-block micronucleus (MN) frequency and global DNA methylation in 294 shoe factory workers and 102 control participants. ResultsWorkers who possessed the following genotypes were associated with high MN frequency: rs25487 AA (FR (95% CI): 1.50 (1.16,1.9), p = 0.002, reference GG); rs1130409 GG (FR (95% CI): 1.28 (1.05,1.55), p = 0.010, reference TT); rs17655 GC (FR (95% CI): 1.18 (1.02,1.38), p = 0.038, reference GG); and rs3212986 TT (FR (95% CI): 1.55 (1.31,1.83), p < 0.001, reference GG). Workers with four and three mutant alleles showed 3.72-fold (OR (95% CI): 3.72 (1.34, 10.03), p = 0.009) and 2.48-fold (OR (95% CI): 2.48 (1.27, 4.88), p = 0.008) increased risk of genetic damage compared with workers with no or one mutant allele, and a dose-response relationship was found by the trend test (p = 0.006). The rs1130409 variant allele (GG+GT) was associated with low global DNA methylation (β=-0.20, 95% CI: −0.42, 0.03, p = 0.045). ConclusionIn benzene-exposed workers, BER and NER pathway polymorphism haplotypes are associated with different levels of chromosome damage and had little effect on global DNA methylation.

Decreased Chromosomal Damage in Lymphocytes of Obese Patients After Bariatric Surgery

The number of bariatric surgeries being performed worldwide has markedly risen. While the improvement in obesity-associated comorbidities after bariatric surgery is well-established, very little is known about its impact on cancer risk. The peripheral lymphocyte micronucleus test is a widely used method for the monitoring of chromosomal damage levels in vivo, and micronucleus frequency positively correlates with cancer risk. Therefore, the aim of this study was to compare the micronucleus frequency before and after bariatric surgery in obese subjects. Peripheral blood mononuclear cells were collected from 45 obese subjects before and at two time-points after bariatric surgery (6 and 12 months) to assess spontaneous micronucleus frequency. Consistent with the increased cancer risk previously shown, bariatric surgery-induced weight loss led to a significant reduction in lymphocyte micronucleus frequency after 12 months. Interestingly, comorbidities such as type 2 diabetes mellitus and metabolic syndrome further seemed to have an impact on the lymphocyte micronucleus frequency. Our findings may indicate a successful reduction of cancer risk in patients following weight loss caused by bariatric surgery.

Chemically dispersed oil is cytotoxic and genotoxic to sperm whale skin cells

Two major oil crises in United States history, the 1989 Exxon-Valdez oil spill in Alaska and the 2010 Deepwater Horizon Oil Rig explosion in the Gulf of Mexico, drew attention to the need for toxicological experiments on oil and chemically dispersed oil. We are still learning the effects these spills had on wildlife. However, little data is known about the toxicity of these substances in marine mammals. The objective of this study is to determine the toxicity of Alaskan oil, as well as chemically dispersed oil. Oil experiments were performed using the water accommodated fraction of Alaskan oil (WAF) and the chemically enhanced water accommodated fraction of Alaskan oil (CEWAF). The Alaskan WAF is not cytotoxic to sperm whale skin cells though it did induce chromosome damage; S9-mediated metabolism did not affect the cytotoxicity of WAF but did increase the levels of chromosome damage. Alaskan CEWAF is more cytotoxic and genotoxic than the WAF; S9 mediated metabolism increased both cytotoxicity and genotoxicity of CEWAF. Analysis of the PAH content of Alaskan WAF and CEWAF revealed a forty-fold increase in the total levels of PAHs in CEWAF compared to WAF. These findings show that chemically dispersed oil leads to higher levels of PAH exposure which are more toxic and likely to lead to longer and more persistent health effects.

The Spindle Assembly Checkpoint Is Required for Hematopoietic Progenitor Cell Engraftment.

SummaryThe spindle assembly checkpoint plays a pivotal role in preventing aneuploidy and transformation. Many studies demonstrate impairment of this checkpoint in cancer cells. While leukemia is frequently driven by transformed hematopoietic stem and progenitor cells (HSPCs), the biology of the spindle assembly checkpoint in such primary cells is not very well understood. Here, we reveal that the checkpoint is fully functional in murine progenitor cells and, to a lesser extent, in hematopoietic stem cells. We show that HSPCs arrest at prometaphase and induce p53-dependent apoptosis upon prolonged treatment with anti-mitotic drugs. Moreover, the checkpoint can be chemically and genetically abrogated, leading to premature exit from mitosis, subsequent enforced G1 arrest, and enhanced levels of chromosomal damage. We finally demonstrate that, upon checkpoint abrogation in HSPCs, hematopoiesis is impaired, manifested by loss of differentiation potential and engraftment ability, indicating a critical role of this checkpoint in HSPCs and hematopoiesis.

Prevention of high-temperature-induced chromosome damage in mouse spermatozoa freeze-dried using Ca2+ chelator-containing buffer alkalinized with NaOH or KOH

In order to protect sperm chromosomes against degradation when they are being stored for relatively high temperatures, we investigated the optimal pH of the freeze-drying solution, EGTA/Tris-HCl buffered solution alkalinized by NaOH (Na-ETBS) or KOH (K-ETBS). Mouse spermatozoa suspended in Na-ETBS or K-ETBS were freeze-dried at pH 5.0–8.4 and stored at 4 °C or 50 °C for 3 days. Some freeze-dried samples were stored at 25 °C for 3 days or 1 month. After storage, samples injected into oocytes using intracytoplasmic sperm injection were assessed for chromosome damage in resulting zygotes. Irrespective of freeze-drying solutions and storage temperatures, almost all the zygotes (97–100%) produced using the spermatozoa freeze-dried at pH 5.0 had structural chromosome aberrations of sperm origin. When freeze-drying was conducted at pH 8.0–8.4 using Na-ETBS, the incidence of chromosome damage decreased to 14–17% in 4 °C storage and 24–26% in 50 °C storage. When freeze-dried in K-ETBS, the lowest level of chromosome damage occurred at pH levels of 7.7–8.4 at 4 °C storage (13–15%) and at pH 7.7–8.0 at 50 °C storage (16–23%). Spermatozoa freeze-dried in Na-ETBS at pH 8.2 and K-ETBS at pH 7.7 showed no significant increase in chromosome damage during 25 °C storage from 3 days to 1 month (11%–20% in Na-ETBS; 13%–18% in K-ETBS). Thus, use of the solutions optimized for short-term storage at high temperature (50 °C, 3 days) permits prolonged storage (1 month) of freeze-dried spermatozoa at room temperature.

GENETIC EFFECTS IN CHILDREN EXPOSED IN PRENATAL PERIOD TO IONIZING RADIATION AFTER THE CHORNOBYL NUCLEAR POWER PLANT ACCIDENT

To study the genetic effects in children exposed to radiation in utero as a result of the Chornobyl nuclear power plant accident accounting the total radiation doses and equivalent radiation doses to the red bone marrow. Incidence of minor developmental anomalies was studied in children exposed to radiation in utero (study group) and in the control group (1144 subjects surveyed in total). Cytogenetic tests using the method of differential G-banding of chromosomes were conducted in 60 children of both study and control groups (10-12-year-olds) and repeatedly in 39 adolescents (15-17-year-olds). A direct correlation was found between the number of minor developmental anomalies and fetal dose of radiation, and a reverse one with fetal gestational age at the time of radiation exposure. Incidence of chromosomal damage in somatic cells of 10-12-year-old children exposed prenatally was associated with radiation dose to the red bone marrow. The repeated testing has revealed that an increased level of chromosomal aberrations was preserved in a third of adolescents. The persons exposed to ionizing radiation at prenatal period should be attributed to the group of carcinogenic risk due to persisting increased levels of chromosome damage. This article is a part of a Special Issue entitled "The Chornobyl Nuclear Accident: Thirty Years After".

Antimutagenic Effect of Afobazole on Blood Leukocytes in Individuals with Reproductive Dysfunction under Conditions of Anthropogenic Load.

Increased frequency of cells with chromosomal aberrations was revealed in 48-h cultures of peripheral blood lymphocytes isolated North Ossetia residents with impaired reproductive function. After 2-week treatment with antimutagenic drug Afobazole, the percentage of cells with chromosomal aberrations significantly decreased from 3.77±0.20 to 2.48±0.24% (p<0.001). Significant differences between chromosome damage levels before and after administration of the drug suggest that Afobazole could be recommended for protective purposes to this group of patients.

Association and interaction of heat shock proteins B1 gene and tumor-suppressor protein p53 gene with chromosome damage levels among coke oven workers

Objective: To investigate the association and interaction of heat shock proteins B1(HSPB1)gene rs2868371 and tumor-suppressor protein p53(TP53)gene rs1042522 polymorphisms with chromosome damage levels among coke oven workers. Methods: We recruited 1 333 male workers from a state-run coke oven plant in Wuhan in September-October 2010. Among them, 949 who had worked in coke oven workplaces, including auxiliary facilities and bottom, side, and top ovens, were nominated as coke oven workers(i.e., exposed), and 384 administrative or medical staff whose workplaces were offices were used as controls. General characteristics and 5 ml of venous blood were collected from each participant. The plasma concentrations of benzo[a]pyrene-diolepoxide(BPDE)-albumin adducts and the lymphocytic micronucleus(MN)frequencies for each individual were detected by ELISA and cytokinesis-block micronucleus assay, respectively. Gene polymorphisms were genotyped using TaqMan assays via quantitative PCR(ABI Prism 7900HT), and the corresponding frequency ratios(FR)with 95% confidence intervals(CI)were computed for all assays. Results: In the exposed group, the MN frequencies were higher in HSPB1 rs2868371 GC, CC, and GC+ CC genotype carriers((3.88 ± 2.88)‰,(4.00 ± 2.66)‰, and(3.91 ± 2.83)‰, respectively)than in rs2868371 GG genotype carriers((3.52±2.67)‰; FR=1.10, 1.13, and 1.11; 95% CI: 1.02-1.19, 1.02-1.25, and 1.03-1.19, respectively), and the HSPB1 rs2868371C allele was associated with increased MN frequency(Ptrend=0.006). Further, in the exposed group, the MN frequencies were lower in TP53 rs1042522 CG and CG+GG genotype carriers((3.63±2.61)‰ and(3.66±2.61)‰, respectively)than in TP53 rs1042522 CC genotype carriers(3.95±3.06)‰(FR=0.87 and 0.90; 95% CI: 0.83-0.96 and 0.84-0.97, respectively). The effect of gene-gene interaction between HSPB1, rs2868371, and TP53 rs1042522 on MN frequency was significant among coke oven workers(P=0.001). Further stratified analyses showed that the effects of the HSPB1 rs2868371C allele in increasing MN frequencies were robust in subjects aged >40 years(FR=1.07, 95% CI: 1.01-1.12), those working >20 years(FR=1.08, 95% CI: 1.02-1.14), those with BMI ≤24 kg/m2(FR=1.07, 95% CI: 1.01-1.13), drinkers(FR=1.09, 95% CI: 1.02-1.16), and workers with higher BPDE-albumin adduct levels(FR=1.07, 95% CI: 1.01-1.13)(Ptrend=0.023, 0.013, 0.029, and 0.020, respectively). The decreasing effect of the TP53 rs1042522 G allele on MN frequencies was robust in subjects aged >40 years(FR=0.94, 95% CI: 0.89-0.99), those with BMI ≤24 kg/m2(FR=0.94, 95% CI: 0.88-0.99), and drinkers(FR=0.94, 95% CI: 0.88-1.00)(Ptrend=0.031, 0.023, and 0.038, respectively). In addition, there were interactions between HSPB1 rs2868371 and age and between HSPB1 rs2868371 and working years in terms of MN frequency(P=0.030 and 0.013, respectively). Conclusion: In coke oven workers, the HSPB1 rs2868371 C and TP53 rs1042522 G alleles were associated with increased and decreased chromosome damage levels, respectively, and their interaction effect on chromosome damage levels was significant.

Assessment of DNA damage in underground coal miners using the cytokinesis-block micronucleus assay in peripheral blood lymphocytes.

Coal miners are exposed to coal dust, containing mineral particles, inorganic compounds and polycyclic aromatic hydrocarbons, and to ionizing radiation. These factors can induce oxidative stress and promote inflammation that leads to DNA damage. The aim of this investigation is to analyse the degree of DNA damage in miners working in underground coal mines in Kemerovo Region (Russian Federation) using the cytokinesis-block micronucleus assay (CBMN) in peripheral blood lymphocytes. The exposed group included 143 coal miners (mean age = 50.11±7.36 years; mean length of service in coal mining conditions = 23.26±9.66 years). As a control group, we have used venous blood extracted from 127 healthy non-exposed men. The mean age in this group was 47.67±8.45 years. We have discovered that coal miners are characterized by a significant increase in the frequency of binucleated lymphocytes with micronuclei (MN), nucleoplasmic bridges (NPBs) and protrusions (NBUDs) compared to non-exposed donors. In addition, we report, for the first time, a reduction of cell proliferation in a cohort of coal miners. These data are evidence of the genotoxic and cytostatic effects of occupational harmful factors of the coal mining industry. No correlation between the level of chromosome damage and age, smoking status or length of service in coal mining conditions were discovered. We suggest that the CBMN assay would be useful in biomonitoring studies to monitor hygiene and prevention strategies in occupational settings in coal mining countries.

Association between exposure to nitric oxide and changes in select molecular markers of health among men in the gold jewelry manufacturing industry

Gold jewelry workers are occupationally exposed to nitric oxide (NO) during the purification of gold. The present study involves the evaluations of chromosome aberrations (CA), micronucleus (MN) and comet assay in lymphocytes and identifies the influence of polymorphisms in DNA repair genes (XRCC1280Arg/His, XRCC1399Arg/Gln) among the gold jewelry workers occupationally exposed to nitric oxide (NO). Among the 84 samples undertaken for study, the non-exposed (categorized based only on age being group I <35years; group II ≥35 years) and exposed subjects (categorized based on age and work duration) constituted 42 subjects each. With increase duration of years of exposure, an increased level of chromosomal damage was observed. Likewise, a higher degree of chromosomal damage and MN was observed in exposed subjects of group II with a total CA of 8.07 ± 3.29 and MN of 10.61 ± 2.25 when compared to group I. Significant increases were also indicated with the overall CA frequency for the exposed subjects for chromatid, chromosome type aberrations and the MN/1000 binucleated cells in peripheral lymphocytes (p < 0.05) in comparison with non-exposed. The analysis of mean tail length of comet assay shows the DNA damage among the group II exposed subjects exhibits higher degree of chromosomal damage, indicating chronic exposure of NO causes the genetic modification, largely influenced by the polymorphic genotypes XRCC1280Arg/His (p < 0.001) and XRCC1399Arg/Gln (0.524). In conclusion, this result of work provides evidence for an apparent genotoxic effect associated with NO exposure. Our result reinforces the higher sensitivity of cytogenetic assays for the biomonitoring of occupationally exposed populations. So there is a strong need to educate those who work with potentially hazardous heavy metals about their adverse effects and highlight the importance of using protective measures.

Association between XRCC1 polymorphisms and chromosome damage in workers exposed to benzene in jewelcrafting industry

To investigate the association between the gene polymorphisms of the DNA damage repair gene X-ray repair cross-complementing gene 1 (XRCC1) and susceptibility to chromosome damage in workers exposed to low-concentration benzene in the jewelcrafting industry. A total of 286 workers exposed to benzene in jewelcrafting enterprises were enrolled as study subjects from January 2013 to December 2014. Gas chromatography was used to measure benzene concentration in workplace, cytokinesis-block micronucleus test was used to analyze the level of chromosome damage in peripheral blood, and the Sequenom technique was used to determine the single nucleotide polymorphisms of XRCC1. The time-weighted average concentration of benzene in workplace was <0.6~1.8 mg/m(3), lower than the national occupational exposure limit (6 mg/m(3)). The distribution of allele frequencies met the Hardy-Weinberg equilibrium in genetics (P>0.05). Increase in age (RR=1.38, 95%CI 1.06~3.75) and increase in working years (RR=1.45, 95%CI 1.18~2.58) were risk factors for the increase in micronucleus frequency. Compared with those with the wild-type homozygous genotype, the individuals with XRCC1 rs25487 CT genotype showed a significantly higher risk of increase in micronucleus frequency (RR=1.51, 95% CI 1.28~3.87, P<0.05) , and the individuals with XRCC1 rs1799782 AA genotype also showed a significantly higher risk of increase in micronucleus frequency (RR=1.65, 95% CI 1.30~3.12, P<0.05). There was no clear association between XRCC1 rs25489 polymorphisms and micronucleus frequency (P>0.05). Exposure to low-concentration benzene may cause chromosome damage in workers exposed to benzene, and the XRCC1 polymorphisms rs 25487 and rs1799782 may be associated with chromosome damage induced by benzene.

Genotoxic and cell-transformation effects of multi-walled carbon nanotubes (MWCNT) following in vitro sub-chronic exposures

BEAS-2B cells were sub-chronically exposed (up to 4 weeks) to low doses of multi-walled carbon nanotubes (MWCNT, NM403). Genotoxic effects were evaluated using the comet and the micronucleus (MN) assays at three different time-points. The expression of different interleukins (IL) such as IL-1B, IL-6 and IL-8, as well as HO-1 as stress marker, was assessed after 3 weeks treatments. As a hallmark biomarker of cell-transforming ability we used the soft-agar assay, which detects anchorage-independent cell growth. Our results show high levels of intracellular reactive oxygen species (ROS) associated to MWCNT exposure. Nevertheless, an important proportion of these ROS levels seems to be associated to solubilized metals contaminants present in NM403, more than to the internalized MWCNT. No primary DNA damage was obtained in the Comet assay although significant levels of chromosome damage were detected using the micronucleus assay. A significant decrease in the expression of the studied cytokines was observed and significant increases in the number of induced colonies were obtained when the ability of induce anchorage-independent growth was determined. These results show that chromosome damage and reducing inflammatory signalling correlated with an increase in attachment-independent growth associated with sub-chronic MWCNT exposure.

Modifying influence of occupational inflammatory diseases on the level of chromosome aberrations in coal miners.

Coal miners are exposed to a wide range of genotoxic agents that can induce genome damage. In addition, miners are characterised by a high risk of the initiation of different occupational inflammatory as well as non-inflammatory diseases. The aim of this investigation is to analyse the modifying influence of occupational pulmonary inflammatory diseases on the level of chromosome aberrations (CAs) in miners working in underground coal mines in Kemerovo Region (Russian Federation). The study group included 90 coal miners with the following pulmonary diseases: chronic dust-induced bronchitis (CDB) and coal-workers' pneumoconiosis (CWP) (mean age = 53.52±2.95 years; mean work experience in coal-mining conditions = 27.70±3.61 years). As a population control (control 1), we have used venous blood extracted from 124 healthy unexposed men. The mean age in this group was 50.92±4.56 years. Control 2 was the venous blood extracted from 42 healthy coal miners (mean age = 51.56±6.38 years; mean work experience in coal-mining conditions = 25.43±8.14 years). We have discovered that coal miners are characterised by an increased general level of CAs as well as an increased frequency of several types of CAs. The significant increase in the frequency of aberration per 100 cells and aberration of chromosome type was discovered in the group of pulmonary disease patients (study group). No correlations of the level of chromosome damage with age, smoking status and work experience in coal-mining conditions were discovered.