The effect of age, gender, diet and lifestyle on DNA damage measured using micronucleus frequency in human peripheral blood lymphocytes

Intervention with a combined physical exercise training to reduce oxidative stress of women over 40 years of age

Exercise training has been shown to be one of the most important lifestyle factor for improving functional performance and health status. Nevertheless, and although some evidence exists about the effects of aerobic training on oxidative stress, there is scarce information concerning the effects of combined exercise training (aerobic and strength training) in oxidative stress. Considering this, the aim of this study was to verify the effects of a combined exercise training in oxidative stress parameters of women over 40 years of age. At baseline, 67 women enrolled in the study and were divided into three groups: younger group (YG, n = 28: 40 to 49 years), middle-aged group (MAG, n = 21: 50 to 59 years) and oldest group (OG, n = 18: above 60 years). These women engaged in a combined exercise training program for 16 weeks, 3 sessions of 60 min per week. At the end of the program, only 31 women (YG: 15; MAG: 8 and OG: 8) were remained in the study and were considered for analysis. Physical assessments (weight, height, body mass index and waist circumference), health and functional parameters (systolic and diastolic blood pressure, fitness tests: supine, latissimus, squat jump, 8 foot up and go test, 30 second chair stand test, and 6 min walk test) and measures of DNA damage (DNA SBs, DNA netFPG), lipid peroxidation (MDA), total antioxidant capacity (TAC) and catalase activity (CAT) were performed before and after the 16-week intervention with combined exercise. The results showed an improvement of overall physical and functional performance as well as a significant decrease in waist perimeter and systolic blood pressure after the exercise program intervention. Regarding the biochemical measures, the exercise training induced a significant decrease in oxidative damage, and a significant increase in the TAC (p < 0.05). The results indicate that combined exercise training induces benefits in functional capacity and reduce damage caused by oxidative stress.

Association between DNA damage, dietary patterns, nutritional status, and non-communicable diseases in coal miners

Several negative health effects have been associated with environmental pollution. Coal mining activities are related to DNA damage. However, the impact of lifestyle as well as environmental exposure must be considered when evaluating the extent of DNA damage. The aim of this cross-sectional study was to analyze nutritional status, dietary patterns, and the prevalence of non-communicable diseases (CNCDs) among coal miners as well as to investigate the correlation of these variables with DNA damage. We used a questionnaire to assess demographics, health, and dietary habits. The nutritional status was measured in terms of BMI (body mass index) and DNA damage was assessed by the comet assay. The sample population was composed of 158 coal miners from the largest coal mining company in South of Brazil, and majority of them were classified as overweight (51.3%) or obese (28.5%). Hypertension was the most common CNCD (50.6%) and a majority of these workers consumed all groups of foods three or more times a week. There was a significant positive correlation between BMI and DNA damage (r = 0.1646, p = 0.04) and this association was stronger (r = 0.2556, p = 0.04) in coal miners with some CNCD. There was no significant correlation between dietary patterns and DNA damage in coal miners. These results suggest that the nutritional status and CNCD increase the extent of DNA damage in coal miners. Since this population is at high occupational risk, specific strategies should be designed to improve the health of these workers, aiming to achieve health equity.

Cytotoxic and genotoxic effects in mechanics occupationally exposed to diesel engine exhaust

Diesel engine exhaust (DEE), which is the product of diesel combustion, is considered carcinogenic in humans. It comprises toxic gases, polycyclic aromatic hydrocarbons (PAHs) and particulate matter which can reach the pulmonary parenchyma and trigger various diseases, including cancer. The aim of the present study was to evaluate the potential cytotoxic and genotoxic effects of DEE exposure on peripheral blood and buccal epithelial cells in mechanics occupationally exposed to DEE. We recruited 120 exposed mechanics and 100 non-exposed control individuals. Significant differences were observed between the two groups in terms of percentage of tail DNA and damage index (DI) in the alkaline comet assay; levels of biomarkers by cytokinesis-block micronucleus cytome (CBMN-Cyt) assay; frequency of micronucleus (MN), nucleoplasmic bridge (NPB), nuclear bud (NBUD) and apoptotic cells (APOP) and levels of biomarkers for micronucleus, karyorrhexis (KRX), karyolysis (KRL) and condensed chromatin (CC) by the buccal micronucleus cytome (BM-Cyt) assay. A significant and positive correlation was found between the frequency of MN in lymphocytes and buccal cells in the exposed group. Also, there was a significant correlation between age and percentage of tail DNA and DI in the comet assay, APOP and MN in the CBMN-Cyt assay and NBUD and MN in the BM-Cyt assay. Additionally, we found a positive and significant correlation of MN frequency in lymphocytes and buccal cells and age and MN frequency in lymphocytes with the time of service (years). Regarding lifestyle-related factors, a significant correlation was observed between meat and vitamin consumption and NBUD formation on CBMN-Cyt and between meat consumption and MN formation on CBMN-Cyt. Of the BM-Cyt biomarkers, there was a correlation between alcohol consumption and NBUD formation and between binucleated cell (BN), pyknosis (PYC), CC and KRL occurrence and family cancer history. These results are the first data in Colombia on the cytotoxic and genotoxic effects induced by continuous exposure to DEE and thus showed the usefulness of biomarkers of the comet, CBMN-Cyt and BM-Cyt assays for human biomonitoring and evaluation of cancer risk in the exposed populations.

The smokeless tobacco habit and DNA damage: A systematic review and meta-analysis

BACKGROUND

The aim of this systematic review was to evaluate the frequency of micronuclei or other DNA damage in the oral mucosa of adults that have smokeless tobacco habits compared to adults that not have these habits.

MATERIAL AND METHODS

We searched PubMed, Scopus, Web of Science, LILACS, BBO and Cochrane Library and SIGLE. We also surveyed gray literature. We included only clinical trials that compare the frequency of micronuclei or other DNA damage in the oral mucosa of adults that have smokeless tobacco habits compared to adults that not have these habits. Quality assessments of the selected trials were evaluated by two independent reviewers, using the Effective Public Health Practice Project - (EPHPP) with modifications.

RESULTS

After the database screening and removal of duplicates, 2574 studies were identified. After title screening, 172 studies remained, and this number was reduced to 25 after careful examination of the abstracts. The standardized mean difference of the frequency of micronuclei between groups was 1.88, with a 95% confidence interval of 1.40 to 2.36 (p < 0.00001). In all analyses heterogeneity was detected.

CONCLUSIONS

Despite the heterogeneity of studies, the frequency of micronuclei was significant bigger in adults who have the smokeless tobacco habit when compared to those not have this habit. The same occurred with the frequency of binucleated cells, karyolisis and karyorrhexis.

Overview of Human Intervention Studies Evaluating the Impact of the Mediterranean Diet on Markers of DNA Damage

The Mediterranean diet (MD) is characterized by high consumption of fruits, vegetables, cereals, potatoes, poultry, beans, nuts, lean fish, dairy products, small quantities of red meat, moderate alcohol consumption, and olive oil. Most of these foods are rich sources of bioactive compounds which may play a role in the protection of oxidative stress including DNA damage. The present review provides a summary of the evidence deriving from human intervention studies aimed at evaluating the impact of Mediterranean diet on markers of DNA damage, DNA repair, and telomere length. The few results available show a general protective effect of MD alone, or in combination with bioactive-rich foods, on DNA damage. In particular, the studies reported a reduction in the levels of 8-hydroxy-2'⁻deoxyguanosine and a modulation of DNA repair gene expression and telomere length. In conclusion, despite the limited literature available, the results obtained seem to support the beneficial effects of MD dietary pattern in the protection against DNA damage susceptibility. However, further well-controlled interventions are desirable in order to confirm the results obtained and provide evidence-based conclusions.

Genotoxicity of inhalational anesthetics and its relationship with the polymorphisms of GSTT1, GSTM1, and GSTP1 genes

Due to their wide applications, concern exists regarding possible genotoxic effects of inhalational anesthetics (IAs) among operating room personnel. This study was undertaken to examine genotoxic properties of co-exposure to nitrous oxide, sevoflurane, and isoflurane on induction of micronucleus (MN) and chromosomal aberrations (CAs) and to determine whether any associations exist between polymorphisms of GST genes and the level of genomic damage measured by MN and CAs assays. Sixty operating room personnel and 60 unexposed referent nurses were studied. The workers' exposure to the IAs was determined. DNA damage was evaluated by MN and CAs assays. Additionally, the GSTM1, GSTT1, and GSTP1 polymorphisms were detected. The mean concentrations of nitrous oxide, isoflurane, and sevoflurane were found to be 850.92 ± 919.78, 2.40 ± 0.86, and 0.18 ± 0.14 ppm, respectively. The frequency of MN and CAs in the exposed group was significantly higher than that of the non-exposed group. The frequency of MN was significantly higher in referent nurses with null GSTT1, compared to referent nurses with positive GSTT1. The frequency of MN was significantly higher in exposed individuals carrying the combined genotype of GSTT1 (-), GSTM1 (-), and GSTP1 AG as compared with subjects carrying a combination of GSTT1 (+), GSTM1 (+), and GSTP1 AA. Statistically significant associations were noted between exposure to the IAs, gender, and the combination of the three GSTs genotypes with MN frequency. These findings indicate that inhalation exposure to IAs induces genotoxic response and the polymorphisms of GSTs genes might modulate the effect of exposure to IAs on MN.

Effect of systemic treatment on the micronuclei frequency in the peripheral blood of patients with metastatic colorectal cancer

Colorectal cancer (CRC) is the third most diagnosed type of cancer affecting males, and the second most diagnosed type of cancer affecting females, and one of the leading causes of cancer-related mortality globally. The estimation of the micronuclei (MN) frequency in peripheral blood lymphocytes (PBLs) from patients with CRC is proposed as a prognostic/predictive easy-to-use biomarker. In this study, we aimed to investigate the effects of systemic treatment on the MN frequency in PBLs from patients with CRC in order to determine the effectiveness of the MN frequency as a biomarker. For this purpose, from 2016 to 2018, we quantified the MN frequency as a prognostic/predictive biomarker in serial samples from 25 patients with metastatic CRC (mCRC) using cytokinesis block micronucleus assay (CBMN assay). The MN frequency in the PBLs of the patients was evaluated before, during the middle and at the end of the therapy (approximately 0, 3 and 6 months). The results revealed a common pattern regarding the fluctuation in the MN frequency. Statistical analysis confirmed that when the disease response was estimated with radiological criteria, a good response was depicted at the MN frequency and vice versa. Consequently, the findings of this study suggest that the MN frequency may serve as a promising prognostic/predictive biomarker for the monitoring of the treatment response of patients with CRC.

Pros and cons of ultra-high-field MRI/MRS for human application

Magnetic resonance imaging and spectroscopic techniques are widely used in humans both for clinical diagnostic applications and in basic research areas such as cognitive neuroimaging. In recent years, new human MR systems have become available operating at static magnetic fields of 7 T or higher (≥300 MHz proton frequency). Imaging human-sized objects at such high frequencies presents several challenges including non-uniform radiofrequency fields, enhanced susceptibility artifacts, and higher radiofrequency energy deposition in the tissue. On the other side of the scale are gains in signal-to-noise or contrast-to-noise ratio that allow finer structures to be visualized and smaller physiological effects to be detected. This review presents an overview of some of the latest methodological developments in human ultra-high field MRI/MRS as well as associated clinical and scientific applications. Emphasis is given to techniques that particularly benefit from the changing physical characteristics at high magnetic fields, including susceptibility-weighted imaging and phase-contrast techniques, imaging with X-nuclei, MR spectroscopy, CEST imaging, as well as functional MRI. In addition, more general methodological developments such as parallel transmission and motion correction will be discussed that are required to leverage the full potential of higher magnetic fields, and an overview of relevant physiological considerations of human high magnetic field exposure is provided.

The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem

Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.

Micronucleus frequency is correlated with antioxidant enzyme levels in workers occupationally exposed to pesticides

Oxidative stress can cause DNA damage leading to nuclear anomalies such as micronuclei (MN). Antioxidant enzymes involved in protection against intracellular oxidative stress include glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT). Pesticide exposure induces oxidative stress and alters antioxidant defense mechanisms, including detoxification and scavenger enzymes. The aim of this study was to evaluate MN frequency in workers occupationally exposed to pesticides and their relationship with antioxidant enzyme activities. A cross-sectional study was conducted in 201 individuals, some of whom were dedicated to the spraying of pesticides. The cytokinesis-block micronucleus (CBMN) assay was conducted, and the activities of GPx, GR, SOD, and CAT were determined. The geometric mean (GM) of MN was 5.4 (1-26 MN). The GM for the antioxidant enzymes was 198.68 U/mL for GPx, 38.96 U/g Hb for GR, 94.78 U/mL for SOD, and 69.77 U/g Hb for CAT. There was a lower MN frequency in males than that in females, and a higher nuclear index. In addition, age affected MN frequency. There was a negative correlation between MN frequency and GPx activity, but a positive one between MN frequency and GR activity. These findings suggest the involvement of GPx in MN frequency.

Cytogenetic status of interventional radiology unit workers occupationally exposed to low-dose ionising radiation: A pilot study

Interventional radiology unit workers represent one of the occupationally most exposed populations to low-dose ionizing radiation. Since there are many uncertainties in research of doses below 100 mSv, this study attempted to evaluate DNA damage levels in chronically exposed personnel. The study group consisted of 24 subjects matched with a control population by the number of participants, age, gender ratio, active smoking status, the period of blood sampling, and residence. Based on regular dosimetry using thermoluminiscent dosimeters, our study group occupationally received a dose of 1.82 ± 3.60 mSv over the last year. The results of the cytokinesis-block micronucleus assay and the comet assay showed a higher nuclear buds frequency (4.09 ± 1.88) and tail length (15.46 ± 1.47 μm) than in the control group (2.96 ± 1.67, 14.05 ± 1.36 μm, respectively). Differences in other descriptors from both tests did not reach statistical significance. Further investigations are needed to develop algorithms for improving personal dosimetry and those that would engage larger biomonitoring study groups.

Cancer follows chromosome missegregation when all endogenous repair mechanisms fail

Almost all solid tumors consist of aneuploid cells with highly abnormal chromosome numbers. Such cancer cells could very well originate from chromosome missegregation which is a disturbingly common phenomenon, happening in 0.01 to 4 percent of cell divisions. Missegregated cells are aneuploid, typically lacking a chromosome or having one in surplus. Missegregated cells have mutation in the gene dose of the perhaps a thousand genes on a chromosome in one step. After missegregation cell division cannot be done right, as at least one daughter cell has a faulty chromosome number. At division in cells with surplus chromosomes the number will tend to increase due to mismatch in the division machinery. The organism has a number of repair mechanisms in place to prevent potential damage of accumulating aneuploidy. The first is the roll-back of the cell division itself, leading to tetraploidy or sometimes two nuclei in one cell; another is the prevention of further divisions. A very important one is induction of apoptosis, the cellular suicide. A special case is the elimination of the nucleus itself in the formation of red blood cells. Many aneuploid cells are probably eliminated by the immune system. A hypothetical mechanism would be the prevention of metastasis. Missegregation increases with age when the chromosomes lose their protective telomere ends at the Hayflick limit after about 50 divisions, and the unraveled chromosomes fuse and break. For cancer to develop all of these repair mechanisms must fail. The hypothesis offers a straightforward rationale for the multiple hit hypothesis of cancer development.

Cytogenotoxic effects of venlafaxine hydrochloride on cultured human peripheral blood lymphocytes

The potential genotoxic effect of venlafaxine hydrochloride (venlafaxine), an antidepressant drug-active ingredient, was investigated by using in vitro chromosome aberrations (CAs) and cytokinesis-block micronucleus (CBMN) assays in human peripheral blood lymphocytes (PBLs). Mitotic index (MI) and cytokinesis-block proliferation index (CBPI) were also calculated to determine the cytotoxicity of this active drug. For this aim, the human PBLs were treated with 25, 50, and 100 µg/ml venlafaxine for 24 h and 48 h. The results of this study showed that venlafaxine significantly induced the formation of structural CA and MN for all concentrations (25, 50, and 100 µg/ml) and treatment periods (24 h and 48 h) when compared with the negative and the solvent control (except 25 µg/ml at 48 h for MN). In addition, the increases in the percentage of structural CA and MN were concentration-dependent for both treatment times. With regard to cell cycle kinetics, venlafaxine significantly decreased the MI at all concentrations, and also CBPI at the higher concentrations for both treatment times as compared to the control groups. The present results indicate for the first time that venlafaxine had significant clastogenic and cytotoxic effects at the tested concentrations (25, 50, and 100 µg/ml) in the human PBLs, in vitro; therefore, its excessive and careless use may pose a potential risk to human health.

Baseline levels of environmental genotoxicity and potential confounding factors using common sole (Solea solea) as sentinel organism

Micronuclei (MN) and nuclear buds (NB) frequency was assessed monthly over a one-year period in erythrocytes of common soles (Solea solea) from the Basque continental shelf, a minor disturbed area, in order to determine baseline levels and potential biotic and abiotic confounding factors within biomonitoring purposes. Both genotoxic parameters presented seasonal variations, although only NB frequency was positively correlated with environmental variables (i.e. water temperature and salinity). On the contrary, MN and NB were not affected by age and gender. Therefore, samples of combined age and gender can be used for biomonitoring genotoxic effects, although sampling period together with water temperature and salinity should be thoroughly considered for NB. Overall, these findings are the first attempt to establish baseline MN (0.10-0.78‰) and NB (0.13-0.82‰) frequencies in common sole from Basque marine waters, which are useful for upcoming data comparisons and integration within genotoxicity evaluation procedures of similar marine environments under biomonitoring scopes.

Buccal micronucleus cytome assay in primary school children: A descriptive analysis of the MAPEC_LIFE multicenter cohort study

BACKGROUND

Recent data support the hypothesis that genetic damage occurring early in life during childhood can play an important role in the development of chronic diseases in adulthood, including cancer.

OBJECTIVES

The objective of this paper, part of the MAPEC_LIFE project, is to describe the frequency of micronuclei and meta-nuclear alterations in exfoliated buccal cells of 6-8year-old Italian children recruited in five Italian towns (i.e., Brescia, Torino, Pisa, Perugia and Lecce) with different air pollution levels.

METHODS

About 200 children per town were recruited from primary schools. Biological samples were collected twice from the same children, in two different seasons (winter 2014-15 and late spring 2015). Cytogenetic damage was evaluated by the buccal micronucleus cytome assay.

RESULTS

Overall,n = 1046 children represent the final cohort of the MAPEC_LIFE study. On the whole, the results showed a higher mean MN frequency in winter (0.42 ± 0.54‰) than late-spring (0.22 ± 0.34‰). MN frequency observed among the five Italian towns showed a trend that follows broadly the levels of air pollution in Italy: the highest MN frequency was observed in Brescia during both seasons, the lowest in Lecce (winter) and Perugia (late-spring).

CONCLUSIONS

To the best of our knowledge, the number of recruited children included in the analysis (n = 1046) is the highest compared to previous studies evaluating the frequency of MN in exfoliated buccal cells so far. MN frequency was associated with winter season and living in towns at various levels of air pollution, suggesting an important role of this exposure in determining early cytogenetic effects.

Persistent Increased Frequency of Genomic Instability in Women Diagnosed with Breast Cancer: Before, during, and after Treatments

This study aimed to evaluate DNA damage in patients with breast cancer before treatment (background) and after chemotherapy (QT) and radiotherapy (RT) treatment using the Comet assay in peripheral blood and the micronucleus test in buccal cells. We also evaluated repair of DNA damage after the end of RT, as well as the response of patient's cells before treatment with an oxidizing agent (H2O2; challenge assay). Fifty women with a mammographic diagnosis negative for cancer (control group) and 100 women with a diagnosis of breast cancer (followed up during the treatment) were involved in this study. The significant DNA damage was observed by increasing in the index and frequency of damage along with the increasing of the frequency of micronuclei in peripheral blood and cells of the buccal mucosa, respectively. Despite the variability of the responses of breast cancer patients, the individuals presented lesions on the DNA, detected by the Comet assay and micronucleus Test, from the diagnosis until the end of the oncological treatment and were more susceptible to oxidative stress. We can conclude that the damages were due to clastogenic and/or aneugenic effects related to the neoplasia itself and that they increased, especially after RT.

Occupational Exposure to Pesticides in Tobacco Fields: The Integrated Evaluation of Nutritional Intake and Susceptibility on Genomic and Epigenetic Instability

Pesticides used at tobacco fields are associated with genomic instability, which is proposed to be sensitive to nutritional intake and may also induce epigenetic changes. We evaluated the effect of dietary intake and genetic susceptibility polymorphisms in MTHFR (rs1801133) and TERT (rs2736100) genes on genomic and epigenetic instability in tobacco farmers. Farmers, when compared to a nonexposed group, showed increased levels of different parameters of DNA damage (micronuclei, nucleoplasmic bridges, and nuclear buds), evaluated by cytokinesis-block micronucleus cytome assay. Telomere length (TL) measured by quantitative PCR was shorter in exposed individuals. Global DNA methylation was significantly decreased in tobacco farmers. The exposed group had lower dietary intake of fiber, but an increase in cholesterol; vitamins such as B6, B12, and C; β-carotene; and α-retinol. Several trace and ultratrace elements were found higher in farmers than in nonfarmers. The MTHFR CT/TT genotype influenced nucleoplasmic bridges, nuclear buds, and TL in the exposed group, whereas TERT GT/TT only affected micronucleus frequency. We observed a positive correlation of TL and lipids and an inverse correlation of TL and fibers. The present data suggest an important role of dietary intake and subjects' genetic susceptibility to xenobiotics-induced damages and epigenetic alterations in tobacco farmers occupationally exposed to mixtures of pesticides.

An updated review of the genotoxicity of respirable crystalline silica

Human exposure to (certain forms of) crystalline silica (CS) potentially results in adverse effects on human health. Since 1997 IARC has classified CS as a Group 1 carcinogen [1], which was confirmed in a later review in 2012 [2]. The genotoxic potential and mode of genotoxic action of CS was not conclusive in either of the IARC reviews, although a proposal for mode of actions was made in an extensive review of the genotoxicity of CS by Borm, Tran and Donaldson in 2011 [3]. The present study identified 141 new papers from search strings related to genotoxicity of respirable CS (RCS) since 2011 and, of these, 17 relevant publications with genotoxicity data were included in this detailed review.

Studies on in vitro genotoxic endpoints primarily included micronucleus (MN) frequency and % fragmented DNA as measured in the comet assay, and were mostly negative, apart from two studies using primary or cultured macrophages. In vivo studies confirmed the role of persistent inflammation due to quartz surface toxicity leading to anti-oxidant responses in mice and rats, but DNA damage was only seen in rats. The role of surface characteristics was strengthened by in vitro and in vivo studies using aluminium or hydrophobic treatment to quench the silanol groups on the CS surface.

In conclusion, the different modes of action of RCS-induced genotoxicity have been evaluated in a series of independent, adequate studies since 2011. Earlier conclusions on the role of inflammation driven by quartz surface in genotoxic and carcinogenic effects after inhalation are confirmed and findings support a practical threshold. Whereas classic in vitro genotoxicity studies confirm an earlier no-observed effect level (NOEL) in cell cultures of 60-70 μg/cm², transformation frequency in SHE cells suggests a lower threshold around 5 μg/cm². Both levels are only achieved in vivo at doses (2–4 mg) beyond in vivo doses (> 200 μg) that cause persistent inflammation and tissue remodelling in the rat lung.

Correlations between Risk Factors for Breast Cancer and Genetic Instability in Cancer Patients-A Clinical Perspective Study

Molecular epidemiological studies have identified several risk factors linking to the genes and external factors in the pathogenesis of breast cancer. In this sense, genetic instability caused by DNA damage and DNA repair inefficiencies are important molecular events for the diagnosis and prognosis of therapies. Therefore, the objective of this study was to analyze correlation between sociocultural, occupational, and lifestyle risk factors with levels of genetic instability in non-neoplastic cells of breast cancer patients. Total 150 individuals were included in the study that included 50 breast cancer patients submitted to chemotherapy (QT), 50 breast cancer patients submitted to radiotherapy (RT), and 50 healthy women without any cancer. Cytogenetic biomarkers for apoptosis and DNA damage were evaluated in samples of buccal epithelial and peripheral blood cells through micronuclei and comet assay tests. Elder age patients (61-80 years) had higher levels of apoptosis (catriolysis by karyolysis) and DNA damage at the diagnosis (baseline damage) with increased cell damage during QT and especially during RT. We also reported the increased frequencies of cytogenetic biomarkers in patients who were exposed to ionizing radiation as well as for alcoholism and smoking. QT and RT induced high levels of fragmentation (karyorrhexis) and nuclear dissolution (karyolysis) and DNA damage. Correlations were observed between age and karyorrhexis at diagnosis; smoking and karyolysis during RT; and radiation and karyolysis during QT. These correlations indicate that risk factors may also influence the genetic instability in non-neoplastic cells caused to the patients during cancer therapies.

Markers of genotoxicity and oxidative stress in farmers exposed to pesticides

The effects of chronic exposure to pesticides can lead to the development of several diseases, including different types of cancer, since the genotoxic and mutagenic capacity of these substances can be observed. The objective of this study is to investigate the relation between the occupational exposure to various pesticides and the presence of DNA damage and oxidative stress. Blood samples from 50 rural workers (41 men and 9 women) exposed to pesticides, 46 controls (20 men and 26 women) from the same city (Antônio Carlos, Santa Catarina state, Brazil) and 29 controls (15 men and 14 women) from another city (Florianópolis, Santa Catarina state, Brazil), were evaluated using the comet assay and the cytokinesis-block micronucleus (CBMN) technique for genetic damage, and the test of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity for the oxidative stress. Cholinesterase activities were also determined, but there was no statistical difference among exposed workers and controls. Significant differences were found in DNA damage among groups. The comet assay performed on peripheral blood lymphocytes of these individuals had a significantly higher DNA damage index in the exposed group comparing to controls (p < 0.0001). MNi (p < 0.001), NBUDs (p < 0.005) and NPBs (p < 0.0001) were also found to be significantly higher in the exposed group. The TBARS values were significantly higher comparing to the Florianopolis control group (p < 0.0001). Even though CAT values were higher than controls, there was no statistical difference. Thus, it is concluded that the exposed individuals, participants of this study, are more subject to suffer genetic damage and, consequently, more susceptible to diseases resulting from such damages.

Assessment of the health status and risk of genotoxic and cytotoxic damage in Argentinian adolescents living near horticultural crops

In some rural areas in Argentina, adolescents may be considered as a group indirectly exposed to agrochemicals because their parents plant small crops near their homes. This could become a health risk to children and adolescents who may be more sensitive to exposure to chemicals than adults. The objective of this study was to evaluate the health status of two different groups of Argentinian adolescents using biochemical parameters, dietary information, and cytogenetic biomarkers of genotoxicity and cytotoxicity. The study groups included 32 adolescents from Montecarlo, who were indirectly exposed to agrochemicals, and 30 unexposed adolescents from Exaltación de la Cruz. The values of total cholesterol, LDL cholesterol, triglycerides, gamma glutamyltransferase, and butyrylcholinesterase (BuChE) were higher (p < 0.05) in males from Exaltación de la Cruz compared with those from Montecarlo. The BuChE activity was also higher (p < 0.05) in females from this region. Furthermore, the consumption of citrus, vegetable-like fruits, tubers, and red meat was more frequent (p < 0.05) in Montecarlo. On the other hand, differences in frequency of biomarkers of genetic damage in lymphocytes were not found (p > 0.05). However, the cytome assay in buccal cells showed that karyorrhectic and pyknotic cells were more frequent (p < 0.05) in the Montecarlo group; whereas, the frequencies of cells with nuclear buds, condensed chromatin and karyolysis were higher (p < 0.05) in the Exaltación de la Cruz group. Despite the differences between the parameters and biomarkers evaluated, the adolescents of Montecarlo did not present health impairment probably due to the type and level of exposure to agrochemicals.

Cytokinesis-block micronucleus cytome assay parameters in peripheral blood lymphocytes of the general population: Contribution of age, sex, seasonal variations and lifestyle factors

The cytokinesis-block micronucleus cytome (CBMN Cyt) assay was used to evaluate the baseline frequency of cytogenetic damage in peripheral blood lymphocytes of the general population (average age, 38.28 ± 12.83 years) in relation to age, sex, body mass index, seasonal variations (season of sampling, period of sampling and different meteorological parameters) and lifestyle factors (smoking habit, alcohol consumption, exposure to medications and diagnostic radiation, physical activity, and family history of cancer). The background frequency of micronuclei (MNi) for the 200 subjects assayed was 5.06 ± 3.11 per 1000 binucleated cells, while the mean frequency of nucleoplasmic bridges (NPBs) was 1.21 ± 1.46 and of nuclear buds (NBUDs) 3.48 ± 2.14. The background frequency of apoptosis and necrosis was 1.58 ± 1.50 and 1.39 ± 1.56, respectively, while the mean nuclear division index (NDI) was 1.99 ± 0.14. The cut-off value, which corresponds to the 95th percentile of the distribution of 200 individual values, was 11 MNi, 4 NPBs and 7 NBUDs. The study also confirmed an association of the above mentioned parameters with age, sex and several lifestyle factors. Moreover, significant confounders based on our results are also sampling season, sampling period and different meteorological parameters that were dependent on the CBMN Cyt assay parameters. In line with the above mentioned, several factors should be taken into account when it comes to the monitoring of exposed populations using cytogenetic biomarkers. Moreover, the normal and cut-off values obtained in this study present background data for the general population, and can later serve as baseline values for further biomonitoring studies.

Cytogenetic instability in populations with residential proximity to open-pit coal mine in Northern Colombia in relation to PM10 and PM2.5 levels

Epidemiological studies indicate that living in proximity to coal mines is correlated with numerous diseases including cancer, and that exposure to PM₁₀ and PM_2.5 components could be associated with this phenomenon. However, the understanding of the mechanisms by which PM exerts its adverse effects is still incomplete and comes mainly from studies in occupationally exposed populations. The aims of this study were to: (1) evaluate DNA damage in lymphocytes assessing the cytokinesis-block micronucleus cytome assay (CBMN-cyt) parameters; (2) identify aneugenic or clastogenic effects in lymphocytes of exposed populations using CREST immunostaining for micronuclei; (3) evaluate multi-elemental composition of atmospheric particulate matter; and (4) verify relation between the DNA damage and PM_2.5 and PM₁₀ levels around the mining area. Analysis revealed a significant increase in micronuclei frequency in binucleated (MNBN) and mononucleated (MNMONO) cells of individuals with residential proximity to open-pit coal mines compared to residents from non-mining areas. Correlation analysis demonstrated a highly significant association between PM_2.5 levels, MNBN frequencies and CREST+ micronuclei induction in exposed residents. These results suggest that PM_2.5 fraction generated in coal mining activities may induce whole chromosome loss (aneuploidy) preferentially, although there are also chromosome breaks. Analysis of the chemical composition of PM_2.5 by PIXE demonstrated that Si, S, K and Cr concentrations varied significantly between coal mining and reference areas. Enrichment factor values (EF) showed that S, Cr and Cu were highly enriched in the coal mining areas. Compared to reference area, mining regions had also higher concentrations of extractable organic matter (EOM) related to nonpolar and polar compounds. Our results demonstrate that PM_2.5 fraction represents the most important health risk for residents living near open-pit mines, underscoring the need for incorporation of ambient air standards based on PM_2.5 measures in coal mining areas.

Clinical and genomic safety of treatment with Ginkgo biloba L. leaf extract (IDN 5933/Ginkgoselect®Plus) in elderly: a randomised placebo-controlled clinical trial [GiBiEx]

BACKGROUND

Numerous health benefits have been attributed to the Ginkgo biloba leaf extract (GBLE), one of the most extensively used phytopharmaceutical drugs worldwide. Recently, concerns of the safety of the extract have been raised after a report from US National Toxicology Program (NTP) claimed high doses of GBLE increased liver and thyroid cancer incidence in mice and rats. A safety study has been designed to assess, in a population of elderly residents in nursing homes, clinical and genomic risks associated to GBLE treatment.

METHODS

GiBiEx is a multicentre randomized clinical trial, placebo controlled, double blinded, which compared subjects randomized to twice-daily doses of either 120-mg of IDN 5933 (also known as Ginkgoselect®Plus) or to placebo for a 6-months period. IDN 5933 is extracted from dried leaves and contains 24.3% flavone glycosides and 6.1% of terpene lactones (2.9% bilobalide, 1.38% ginkgolide A, 0.66% ginkgolide B, 1.12% ginkgolide C) as determined by HPLC. The study was completed by 47 subjects, 20 in the placebo group and 27 in the treatment group. Clinical (adverse clinical effect and liver injury) and genomic (micronucleus frequency, comet assay, c-myc, p53, and ctnnb1 expression profile in lymphocytes) endpoints were assessed at the start and at the end of the study.

RESULTS

No adverse clinical effects or increase of liver injury markers were reported in the treatment group. The frequency of micronuclei [Mean Ratio (MR) = 1.01, 95% Confidence Intervals (95% CI) 0.86-1.18), and DNA breaks (comet assay) (MR = 0.91; 95% CI 0.58-1.43), did not differ in the two study groups. No significant difference was found in the expression profile of the three genes investigated.

CONCLUSIONS

None of the markers investigated revealed a higher risk in the treatment group, supporting the safety of IDN 5933 at doses prescribed and for duration of six months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03004508 , December 20, 2016. Trial retrospectively registered.

In vivo Exposure Effects of 99mTc-methoxyisobutylisonitrile on the FDXR and XPA Genes Expression in Human Peripheral Blood Lymphocytes

Objective(s):

In recent years, the application of radiopharmaceuticals in nuclear medicine has increased substantially. Following the diagnostic procedures performed in nuclear medicine departments, such as myocardial perfusion imaging, patients generally receive considerable doses of radiation. Normally, radiation-induced DNA damages are expected following exposure to a low-dose ionizing radiation. In order to detect molecular changes, high-sensitivity techniques must be utilized. The aim of this study was to assess the effect of a low-dose (below 10 mSv) gamma ray on gene expression using quantitative real-time polymerase chain reaction (qRT-PCR).

Methods:

Blood samples were obtained from 20 volunteer patients who underwent myocardial perfusion imaging. They were given various doses of Technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI). After that, peripheral blood mononuclear cells (PBMNs) were derived, and then total RNA was extracted and reverse-transcribed to cDNA. Finally, the expression levels of xeroderma pigmentosum complementation group-A (XPA) and ferredoxin reductase (FDXR) genes were determinded through qRT-PCR technique using SYBR Green.

Results:

XPA and FDXR expression levels were obtained following a very low-dose ionizing radiation. A significant up-regulation of both genes was observed, and the gene expression level of each individual patient was different. If differences in the administered activity and radiosensitivity are taken into account, the observed differences could be justified. Furthermore, gender and age did not play a significant role in the expression levels of the genes under study.

Conclusion:

The up-regulation of FDXR after irradiation revealed the high-sensitivity level of this gene; therefore, it could be used as an appropriate biomarker for biological dosimetry. On the other hand, the up-regulation of XPA is an indication of DNA repair following radiation exposure. According to linear no-threshold model (LNT) and the results obtained from this study, a very low dose of ionizing radiation could bring about adverse biological effects at molecular level in the irradiated person.

Association Between Inherited Thrombophilia in Pregnancy and Micronucleus Frequency in Peripheral Blood Lymphocytes

The aim of this study was to determine possible predictors of an increased frequency of micronucleus (MN) and the impact of thrombophilia on the chromosomal instability in peripheral blood lymphocytes (PBL) of pregnant women in their first trimester. This study was designed as a case-control study on 74 pregnant women. It was performed in the gestational age of 11 to 14 weeks, when blood samples were collected and incubated for 72 hours. The individual MN frequency in PBL was measured by cytokinesis-block micronucleus (CBMN) assay. Women were grouped in control group [≤4 MN/1000 binucleated (BN) cells] and case group (>4 MN/1000 BN cells). Potential mutagenic effects of exogenous/endogenous factors in pregnant women were analyzed. By analyzing the given results, it can be concluded that pregnant women with thrombophilia have 26.69-times more chance of having a frequency of >4 MN/1000 BN than pregnant women with no thrombophilia. Our research was primarily aimed at showing that the presence of thrombophilia was a statistically important predictor of an increased MN frequency in pregnant women and it can predict about one-third of the total variance in MN frequency in the studied population.

Telomeres, Nutrition, and Longevity: Can We Really Navigate Our Aging?

Telomeres are dynamic chromosome-end structures that serve as guardians of genome stability. They are known to be one of the major determinants of aging and longevity in higher mammals. Studies have demonstrated a direct correlation between telomere length and life expectancy, stress, DNA damage, and onset of aging-related diseases. This review discusses the most important factors that influence our telomeres. Various genetic and environmental factors such as diet, physical activity, obesity, and stress are known to influence health and longevity as well as telomere dynamics. Individuals currently have the opportunity to modulate the dynamics of their aging and health span, monitor these processes, and even make future projections by following their telomere dynamics. As telomeres react to positive as well as negative health factors, we should be able to directly influence our telomere metabolism, slow their deterioration, and diminish our aging and perhaps extend our life and health span.

Influence of vitamin intake and MTHFR polymorphism on the levels of DNA damage in tobacco farmers

BACKGROUND

Genetic damage may occur spontaneously under normal metabolic circumstances, inadequate intake of nutrients, and excessive exposure to environmental mutagens.

OBJECTIVES

To evaluate the influence of the intake of micronutrients vitamin B12, vitamin B6, and folate and of the polymorphism methylenetetrahydrofolate reductase (MTHFR) C677T on the induction of DNA damage in tobacco farmers.

METHODS

The study involved 66 men and 44 women engaged in tobacco cultivation in the region of Venâncio Aires (Rio Grande do Sul state, Brazil). Peripheral blood samples were collected to analyze DNA damage using the Comet assay, the micronucleus (MN) test and MTHFR C677T polymorphism. Dietary intake was evaluated based on the mean values obtained from three 24-h diet recall questionnaires, and nutrient intake data were computerized and estimated in the Food Processor SQL 10.9 program. The statistical tests used to generate the stated results were Kruskal-Wallis test, Exact Fisher's test, and multivariate linear regression analysis.

RESULTS

DNA damage was significantly higher in individuals who had an inadequate intake of folate, vitamin B12, and vitamin B6 (P < 0.01) assessed by Comet assay. In relation to MN test results, buccal cells showed MN frequency higher in individuals with inadequate intake of vitamin B6 (P < 0.01). No difference was observed in MN lymphocytes frequency. No significant association was detected between MTHFR C677T polymorphism and DNA damage in tobacco farmers.

CONCLUSION

Our results suggest that folate, vitamin B12, and vitamin B6 deficiency may be associated with genotoxic effect in individuals exposed to pesticides.

Radio-adaptive response in peripheral blood lymphocytes of individuals residing in high-level natural radiation areas of Kerala in the southwest coast of India

The present study investigates whether the chronic low-dose radiation exposure induces an in vivo radio-adaptive response in individuals from high-level natural radiation areas (HLNRA) of the Kerala coast. Peripheral blood samples from 54 adult male individuals aged between 26 and 65 years were collected for the study with written informed consent. Each of the whole blood sample was divided into three, one was sham irradiated, second and third was exposed to challenging doses of 1.0 and 2.0 Gy gamma radiation, respectively. Cytokinesis-block micronucleus (CBMN) assay was employed to study the radio-adaptive response. Seventeen individuals were from normal-level natural radiation area (NLNRA ≤1.5 mGy/year) and 37 from HLNRA (> 1.5 mGy/year). Based on the annual dose received, individuals from HLNRA were further classified into low-dose group (LDG, 1.51-5.0 mGy/year, N = 19) and high-dose group (HDG >5.0 mGy/year, N = 18). Basal frequency of micronucleus (MN) was comparable across the three dose groups (NLNRA, LDG and HDG, P = 0.64). Age of the individuals showed a significant effect on the frequency of MN after challenging dose exposures. The mean frequency of MN was significantly lower in elder (>40 years) individuals from HDG of HLNRA as compared to the young (≤40 years) individuals after 1.0 Gy (P < 0.001) and 2.0 Gy (P = 0.002) of challenging doses. However, young and elder individuals within NLNRA and LDG of HLNRA showed similar frequency of MN after the challenging dose exposures. Thus, increased level of chronic low-dose radiation (>5.0 mGy/year) seems to act as a priming dose resulting in the induction of an in vivo radio-adaptive response in elder individuals of the Kerala coast.

Cytogenetic surveillance of persons occupationally exposed to genotoxic chemicals

Human genotoxic exposures can occur environmentally, occupationally, or medicinally. The aim of this study was to assess cytogenetic damage (chromosomal aberrations and micronuclei) in persons exposed to chemical agents in medical, agricultural, and industrial occupations. The results showed influences of age, gender, occurrence, and duration of exposure on the extent of cytogenetic damage, but no influence of smoking. Persons exposed to pesticides were allocated significantly higher values of most examined parameters. Among all tested parameters, logistic regression analysis marked tMN, CB, and iCB as the best predictors with high discrimination accuracy of separation between exposed and unexposed persons. The obtained data encourage us to consider certain cytogenetic parameters as valuable markers for preventive medical screening as the extent of cytogenetic damage reflects cumulative exposure events and possible health consequences related to chronic occupational genotoxic exposure.

Role of Macronutrients and Micronutrients in DNA Damage: Results From a Food Frequency Questionnaire

The links between diet and genomic instability have been under investigation for several decades, and evidence suggests a significant causal or preventive role for various dietary factors. This study investigates the influence of macronutrients (calories, protein, and glucides) and micronutrients, such as vitamins and minerals, as assessed by a food frequency questionnaire, on genotoxicity biomarkers measured by cytokinesis-blocked micronucleus assay and comet assay. The results found significant positive and negative correlations. Micronucleus frequency tends to increase with higher intake of caffeine, calcium, magnesium, zinc, and protein (P < .05, Spearman correlation). Calorie and omega-6 intakes are negatively correlated with DNA damage measured by the comet assay. These results are somewhat controversial because some of the correlations found are contrary to dominant views in the literature; however, we suggest that unraveling the association between diet and genetic instability requires a much better understanding of the modulating role of macronutrients and micronutrients.

Aerial pesticide application causes DNA damage in pilots from Sinaloa, Mexico

The use of pesticides in agricultural production originates residues in the environment where they are applied. Pesticide aerial application is a frequent source of exposure to pesticides by persons dedicated to agricultural practices and those living in neighboring communities of sprayed fields. The aim of the study was to assess the genotoxic effects of pesticides in workers occupationally exposed to these chemicals during their aerial application to agricultural fields of Sinaloa, Mexico. The study involved 30 pilots of airplanes used to apply pesticides via aerial application and 30 unexposed controls. Damage was evaluated through the micronucleus assay and by other nuclear abnormalities in epithelial cells of oral mucosa. The highest frequency ratios (FR) equal to 269.5 corresponded to binucleated cells followed by 54.2, corresponding to cells with pyknotic nuclei, 45.2 of cells with chromatin condensation, 3.7 of cells with broken-egg, 3.6 of cells with micronucleus, and 2.0 of karyolytic cells. Age, worked time, smoking, and alcohol consumption did not have significant influence on nuclear abnormalities in the pilots studied. Pesticide exposure was the main factor for nuclear abnormality results and DNA damage. Marked genotoxic damage was developed even in younger pilots with 2 years of short working period, caused by their daily occupational exposure to pesticides.

Epigenetic signatures of childhood abuse and neglect: Implications for psychiatric vulnerability

Childhood maltreatment is a key risk factor for poor mental and physical health. Recently, variation in epigenetic processes, such as DNA methylation, has emerged as a potential pathway mediating this association; yet, the extent to which different forms of maltreatment may be characterized by unique vs shared epigenetic signatures is currently unknown. In this study, we quantified DNA methylation across the genome in buccal epithelial cell samples from a high-risk sample of inner-city youth (n = 124; age = 16-24; 53% female), 68% of whom reported experiencing at least one form of maltreatment while growing up. Our analyses aimed to identify methylomic variation associated with exposure to five major types of childhood maltreatment. We found that: (i) maltreatment types differ in the extent to which they associate with methylomic variation, with physical exposures showing the strongest associations; (ii) many of the identified loci are annotated to genes previously implicated in stress-related outcomes, including psychiatric and physical disorders (e.g. GABBR1, GRIN2D, CACNA2D4, PSEN2); and (iii) based on gene ontology analyses, maltreatment types not only show unique methylation patterns enriched for specific biological processes (e.g. physical abuse and cardiovascular function), but also share a 'common' epigenetic signature enriched for biological processes related to neural development and organismal growth. A stringent set of sensitivity analyses were also run to identify high-confidence associations. Together, findings lend novel insights into epigenetic signatures of childhood abuse and neglect, point to novel potential biomarkers for future investigation and support a molecular link between maltreatment and poor health outcomes. Nevertheless, it will be important in future to replicate findings, as the use of cross-sectional data and high rates of polyvictimization in our study make it difficult to fully disentangle the shared vs unique epigenetic signatures of maltreatment types. Furthermore, studies will be needed to test the role of potential moderators in the identified associations, including age of onset and chronicity of maltreatment exposure.

Mapping the factors affecting the frequency and types of micronuclei in an elderly population from Southern Bohemia

The micronucleus assay is one of the most common methods used to assess chromosomal damage (losses or breaks) in human peripheral blood lymphocytes (PBL) in genetic toxicology. Most studies have focused on analyzing total micronuclei (MN), but identifying the content of MN can provide more detailed information. The main aim of this study was to map the factors affecting the frequency and types of micronuclei in binucleated cells (BNC) in elderly population. Fluorescence in situ hybridization using Human Pan Centromeric Chromosome Paint was used to identify centromere positive (CEN+) or centromere negative (CEN-) MN. A group of 95 men from Southern Bohemia, Czech Republic (average age 68.0±6.8 years) was followed repeatedly, in spring and fall 2014. The study participants were former workers of the uranium plant "MAPE Mydlovary" (processing uranium ore from 1962 to 1991), and controls. The general profile of individual types of MN, and the effect of the season, former uranium exposure, age, smoking status, weight, and X-ray examination on the level and type of MN were analyzed. The results of this study showed: (i) a stable profile of BNC with MN based on the number of MN during two seasons; (ii) an increase of the number of CEN+ MN from spring to fall; (iii) a lower frequency of the total MN in the exposed group than in controls with a significant difference in the percentage of aberrant cells (%AB.C.) in the fall; (iv) no clear effect of age, smoking and BMI on DNA damage in this group; (v) lower DNA damage levels in former uranium workers who received X-ray examination later in life. In summary, the results indicate a trend of seasonal changes of individual types of MN and suggest that former exposure can have a protective effect on the level of DNA damage in case of future exposure.

Cytogenetic biomarkers in detection of genotoxic effects of gestagens in peripheral blood lymphocytes in vitro and in vivo

Gestagens are the most frequently used steroid hormones in hormone-replacement therapy in the treatment of threatened miscarriage during the first trimester of pregnancy. This therapy has been applied in a large number of women with threatened abortion, despite various degrees of success of its efficacy. Genetic factors play a key role in miscarriages, especially in the initial stages. Cytogenetic biomarkers such as micronucleus (MN) test, chromosomal aberrations (CAs), and sister chromatid exchanges (SCEs) provide information on DNA damage. Cytogenetic markers detecting DNA damage have become very popular and useful in analysing genetic risk associated with hormone-replacement therapy. Cytogenetic studies presented heterogenous information. In many in vitro studies synthetic gestagens have been shown to induce genotoxic effects, and it was evaluated using three cytogenetic biomarkers. Genotoxic effects of gestagens have also been confirmed in in vivo studies that were conducted involving patients who received gestagen therapy during pregnancy and their newborns. However, some studies have shown that hormone-replacement therapy does not have genotoxic effects. In this paper, we summarize the results from previous studies. We also describe the usefulness of these biomarkers in the detection of genotoxic effects of hormone-replacement therapy.

A population study using the human erythrocyte PIG-A assay

Erythrocyte-based PIG-A assay is sensitive and reliable in detecting exposure to mutagenetic agents in animal studies, but there are few data from human populations. In this study, we employed a method for detecting CD59 phenotypic variants, resulting from mutation in the PIG-A gene, in human red blood cells (RBCs), and determined the CD59-deficient RBC (RBC^CD59- ) frequencies in 217 subjects from general population. The majority of subjects had a relatively low mutant frequencies (MFs) (average, 5.25 ± 3.6 × 10^-6 , median, 4.38 × 10^-6 , for all subjects), but with males having a significantly greater MFs (5.97 ± 4.0 × 10^-6 ) than females (4.19 ± 2.5 ×10^-6 ). There was no correlation between MFs and age. In addition, MFs showed no difference between smoker and nonsmoker, and also no association with smoke duration in male subjects. However, there was a significant correlation between cigarette-pack-years which indicated that the MF was only slightly elevated with the increase of cigarette-pack-years. Moreover, intraindividual variations were investigated in three volunteer subjects over 300 days, and the MFs were relatively stable and repeatable. Furthermore, a pilot study by using white blood cell (WBC) assay based on labeling with FLAER was performed in volunteer subjects. The MFs of FLAER-deficient WBC (WBC^FLAER- ) and RBC^CD59- were consistently elevated in two subjects. Our findings provide baseline data that will be helpful in designing further studies using the PIG-A assay to monitor the genotoxic effects of carcinogens in human populations. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.