Micronuclei In Lymphocytes Research Articles

Celecoxib mitigates genotoxicity induced by ionizing radiation in human blood lymphocytes.

Ionizing radiation causes DNA damage and chromosome abbreviations on normal cells. The radioprotective effect of celecoxib (CLX) was investigated against genotoxicity induced by ionizing radiation in cultured human blood lymphocytes. Peripheral blood samples were collected from human volunteers and were incubated at different concentrations at 1, 5, 10 and 50 μM of CLX for two hours. At each dose point, the whole blood was exposed in vitro to 150 cGy of X-ray, and then the lymphocytes were cultured with mitogenic stimulation to determine the micronucleus frequency in cytokinesis blocked binucleated lymphocytes. Incubation of the whole blood with CLX exhibited a significant decrease in the incidence of micronuclei in lymphocytes induced by ionizing radiation, as compared with similarly irradiated lymphocytes without CLX treatment. The maximum reduction on the frequency of micronuclei was observed at 50 μM of CLX (65% decrease). This data may have an important possible application for the protection of human lymphocytes from the genetic damage induced by ionizing irradiation in human exposed to radiation.

The relationship of micronucleus frequency and nuclear division index with coronary artery disease SYNTAX and Gensini scores.

Objective:We aimed to evaluate the relationship of micronucleus (MN) frequency and nuclear division index (NDI) with SYNTAX and Gensini scores and thrombolysis in myocardial infarction (TIMI) frame counts of coronary arteries in patients undergoing coronary angiography.Methods:In a single-center prospective observational study, a total of 63 individuals, 48 consecutive patients with coronary artery disease (CAD) and 15 healthy people were included. Before coronary angiography (exposure to X-ray), blood samples were collected for lymphocyte cultures, MN and NDI measurements. According to the SYNTAX and Gensini scores, patients were allocated into two groups. Group 1 and 2 included the patients with SYNTAX scores <22 and ≥22 points, respectively. Similarly, groups according to Gensini scores included the ones <23 and ≥23 points. MN test was used for in vitro studies in human peripheral lymphocytes. Binucleated lymphocytes were calculated for each patient.Results:MN frequency was significantly higher in group 2 than group 1 and in group 1 than control group (p<0.001). NDI was significantly higher in control group than group 1 and in group 1 than group 2 (p=0.003). MN frequency had positive but moderate correlation with SYNTAX and Gensini scores and TFCs of left anterior descending (LAD), circumflex and right coronary arteries (r=0.394, p=0.003; r=0.458, p<0.001; r=0.425, p<0.001; r=0.469, p<0.001; and r=0.475, p<0.001, respectively).Conclusion:We can conclude that as the degree of atherosclerosis increases and coronary flow worsens, MN frequency increases and NDI decreases. Our results may help to elucidate the relationship of DNA damage in pathophysiology of atherosclerosis and endothelial dysfunction in patients with stable CAD.

Micronucleus, Nucleoplasmic Bridge, and Nuclear Budding in Peripheral Blood Cells of Workers Exposed to Low Level Benzene.

Background:Benzene is one of the important occupational pollutants. There are some reports about the leukemogenic effects related to low-level exposure to benzene.Objective:To study the frequency of micronucleus (MN), nucleoplasmic bridge (NB), and nuclear budding (NBUD) in the peripheral blood lymphocytes of petrochemical workers with low level exposure to benzene.Methods:We enrolled 50 workers exposed to low-level benzene and 31 unexposed workers of a petrochemical industry. After exclusion of 3 samples, peripheral blood lymphocytes of the remaining 47 exposed and 31 unexposed workers were analyzed for the frequency of MN, NB, and NBUD by cytochalasin-blocked MN technique.Results:MN was present in 28 (60%) exposed and 18 (58%) unexposed workers. NB was observed in 6 (13%), and 2 (7%) exposed and unexposed workers, respectively; the frequency for NBUD was 20 (43%), and 13 (42%), respectively. No significant difference was found in the observed frequencies of MN, NB, and NBUD in the peripheral blood lymphocytes between the exposed and unexposed group workers.Conclusion:Occupational exposure to low-level benzene does not increase the frequency of MN, NB, and NBUD in the peripheral blood lymphocytes, biomarkers for DNA damage.

Effect of CYP3A4 genetic polymorphisms on the genotoxicity of 4,4′-methylene-bis(2-chloroaniline)-exposed workers

ObjectivesWe investigated the relationship between 4,4’-methylene-bis(2-chloroaniline) (MBOCA) exposure and micronucleus (MN) frequency, and how this association was affected by genetic polymorphism of the cytochrome P450 enzyme (CYP3A4).MethodsWe divided the study...

Heavy metals: Results of a systematic review of human exposure studies using the lymphocytes micronucleus assay

The use of cooperative learning as a pedagogical framework in teacher-training colleges and universities has gained special relevance in the last decade. What do we know about the impact of cooperative learning-based interventions on future teachers so far? The purpose was to provide a contemporary picture on cooperative learning interventions in teacher education students conducting a systematic review. More specifically, this paper aimed to answer the following research questions: (1) What was the focus of studies investigating the benefits of cooperative learning in future teachers? (2) Which learning outcomes have been observed? (3) What were the main effects in student-teachers? Several electronic literature databases were involved in the process (Web of Science, EBSCO host, Scopus, ERIC, PsycINFO, SciELO). Quantitative, qualitative or mixed intervention studies were assessed. Nineteen eligible articles, involving 1944 teacher education students, were included to evaluate, organize and produce a high-level synthesis of evidence of this methodological approach. A comprehensive literature review is presented on its effects and learning outcomes. Findings showed that this teaching strategy can be useful for teacher education students’ global development: content knowledge, pedagogical content knowledge, personal, inter-personal and transversal skills, and professional skills and competencies. Unfortunately, these improvements are not linear and they need time and high-structured experiences. Cooperative learning has been found a positive framework in teacher education programs worldwide to train future teachers. Formative implications and future research are discussed.El uso del aprendizaje cooperativo como marco pedagógico en los centros universitarios de formación del profesorado ha cobrado especial relevancia en la última década. ¿Qué sabemos hasta ahora sobre el impacto de las intervenciones de aprendizaje cooperativo en los futuros docentes? El propósito de este estudio ha sido proporcionar una imagen contemporánea sobre la utilización del aprendizaje cooperativo en la formación del profesorado mediante una revisión sistemática. Más específicamente, este estudio ha tenido como objetivo responder a las siguientes preguntas de investigación: (1) ¿Cuál ha sido el enfoque de los estudios que investigaron los beneficios del aprendizaje cooperativo en la formación del profesorado? (2) ¿Qué resultados de aprendizaje se han observado? (3) ¿Cuáles han sido los principales efectos en los futuros docentes? Varias bases de datos electrónicas han sido empleadas en el proceso de búsqueda (Web of Science, EBSCO host, Scopus, ERIC, PsycINFO, SciELO). Estudios de intervención cuantitativos, cualitativos o mixtos han sido analizados. Un total de 19 artículos, involucrando a 1944 estudiantes, han sido incluidos para evaluar, organizar y producir una síntesis de calidad sobre la evidencia en el empleo de este enfoque metodológico. Se presenta una revisión exhaustiva de la literatura sobre sus efectos y resultados de aprendizaje. Los hallazgos muestran que esta estrategia de enseñanza puede ser útil para el desarrollo global de los futuros docentes: conocimiento del contenido, conocimiento del contenido pedagógico, habilidades personales, interpersonales y transversales, y habilidades y competencias profesionales. Desafortunadamente, estas mejoras no son lineales y necesitan tiempo y experiencias altamente estructuradas. El aprendizaje cooperativo se ha mostrado como un formato instructivo positivo en los programas de formación de docentes de todo el mundo. Se discuten las implicaciones formativas y la investigación futura.

Influence of exposure to pesticides on telomere length in tobacco farmers: A biology system approach

Various pesticides in the form of mixtures must be used to keep tobacco crops pest-free. Recent studies have shown a link between occupational exposure to pesticides in tobacco crops and increased damage to the DNA, mononuclei, nuclear buds and binucleated cells in buccal cells as well as micronuclei in lymphocytes. Furthermore, pesticides used specifically for tobacco crops shorten telomere length (TL) significantly. However, the molecular mechanism of pesticide action on telomere length is not fully understood. Our study evaluated the interaction between a complex mixture of chemical compounds (tobacco cultivation pesticides plus nicotine) and proteins associated with maintaining TL, as well as the biological processes involved in this exposure by System Biology tools to provide insight regarding the influence of pesticide exposure on TL maintenance in tobacco farmers. Our analysis showed that one cluster was associated with TL proteins that act in bioprocesses such as (i) telomere maintenance via telomere lengthening; (ii) senescence; (iii) age-dependent telomere shortening; (iv) DNA repair (v) cellular response to stress and (vi) regulation of proteasome ubiquitin-dependent protein catabolic process. We also describe how pesticides and nicotine regulate telomere length. In addition, pesticides inhibit the ubiquitin proteasome system (UPS) and consequently increase proteins of the shelterin complex, avoiding the access of telomerase in telomere and, nicotine activates UPS mechanisms and promotes the degradation of human telomerase reverse transcriptase (hTERT), decreasing telomerase activity.

Chromosomal aberrations, sister chromatid exchanges, and micronuclei in lymphocytes of oncology department personnel handling anti-neoplastic drugs

Objective: Concern exists regarding the possible hazards to the personnel handling anti-neoplastic drugs. The purpose of the present study was to assess the genotoxicity induced by anti-neoplastic agents in oncology department personnel. Materials and methods: To do this, the frequency of chromosomal aberrations (CAs) induced in peripheral blood lymphocytes was assessed at G0 phase of the cell cycle using metaphase analysis, cytokinesis block-micronucleus (MN) assay and sister chromatid exchange (SCE) assay. These cytogenetic end points were measured among 71 nurses in oncology department and 10 drugstore personnel handling and preparing anti-neoplastic drugs. The results were compared to those of 74 matched nurses for age and sex not exposed to any anti-neoplastic agents. Results: There was no significant difference between the age of study subjects and control group (p > 0.05). The results showed that the mean frequency of cytogenetic damages in terms of CAs [chromatid breaks (p = 0.01), chromosome breaks (p = 0.005), total CAs (p = 0.001)], MN formation (p = 0.001), and SCE (p = 0.004) in lymphocytes of personnel handling anti-neoplastic drugs were significantly higher than those in control unexposed group. Conclusion: Results of the present study demonstrate the cytogenetic damage in peripheral blood lymphocytes of oncology department personnel. Suitable training and proper knowledge when handling anti-neoplastic drugs are emphasized to avoid potential health hazards caused by cytostatic agents.

Reduced LINE-1 methylation is associated with arsenic-induced genotoxic stress in children.

Early life exposure to arsenic has profound effect towards development of arsenic induced toxic outcomes. Some districts in the state of West Bengal, India are highly affected by arsenic, mainly through ground water. In children, not much of the toxic outcomes like dermatological lesions are observed but it is thought that the exposure leads to transient alteration in their biological processes that leads to various deleterious health effects later on. We evaluated the global methylation status by analyzing the LINE-1 methylation profile in children from arsenic exposed region between the age group 5-15years along with the cytogenetic stress induced by arsenic as measured by lymphocyte micronucleus (MN) frequency. A total of 52 arsenic exposed and 32 unexposed children were analyzed. Whole blood DNA was used to measure the LINE-1 methylation by qRT-MSP. We found a significant association of MN-frequency in exposed individuals with highly depleted LINE-1 methylation compared to the exposed individuals with near baseline (which was comparable to unexposed control) methylation index as well as with those with the hypermethylated LINE-1 promoters. From our results, we interpret that LINE-1 methylation index may serve as a potent global epigenetic mark to detect the degree of arsenic genotoxicity at a very early age. We propose that this may be utilized to determine the extent of toxic influence exerted by arsenic, from a very early age.

The antioxidant, cytotoxic, and antigenotoxic effects of galangin, puerarin, and ursolic acid in mammalian cells

Phenolic compounds not only contribute to the sensory qualities of fruits and vegetables but also exhibit several health protective properties. Galangin, puerarin, and ursolic acid are commonly used plant phenolics in folk medicine. In this study, the antioxidant capacities of galangin, puerarin, and ursolic acid by the trolox equivalent antioxidant capacity (TEAC) assay and the cytotoxic effects by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in V79 cells were investigated. The genotoxic potentials of galangin, puerarin, and ursolic acid were evaluated by micronucleus (MN) and alkaline COMET assays in human lymphocytes and in V79 cells. Galangin, puerarin, and ursolic acid (10, 100, 500, 1000, 2000, 5000, 10 000, and 20 000 μM) were found to have antioxidant activities at the studied concentrations. IC50 values of galangin, puerarin, and ursolic acid in V79 cells were found to be 275.48 μM, 2503.712 μM, and 224.85 μM, respectively. Galangin, puerarin, and ursolic acid, at the all concentrations, have not exerted genotoxic effects and galangin, puerarin, and ursolic acid revealed a reduction in the frequency of MN and DNA damage induced by H2O2.

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.

Evaluation of cytological radiation damage to lymphocytes after I-131 metaiodobenzylguanidine therapy by the cytokinesis-blocked micronucleus assay.

The purpose of this study was to evaluate the degree of cytological radiation damage to lymphocytes occurring after I-131 metaiodobenzylguanidine (MIBG) therapy as determined by the cytokinesis-blocked micronucleus assay. The chromosomal damage to lymphocytes induced by I-131 in vivo should result in augmentation of the number of cells with micronuclei. We studied 15 patients with pheochromocytoma (14/15) or ganglioneuroma (1/15), who were treated initially with 7.4GBq of I-131-MIBG. Isolated lymphocytes collected from patients 10days after the therapy were harvested and treated according to the cytokinesis-blocked method of Fenech and Morley. Serial blood samples were obtained periodically only from two patients for 2years after therapy. Micronucleus number of micronuclei per 500 binucleated cells was scored by visual inspection. As controls, lymphocytes from the same patients before the therapy were also studied. In an in vitro study, lymphocytes from eight normal volunteers were exposed to doses varying from 0.5 to 2Gy and studied with the same method. The mean number (mean±SD) of micronuclei after treatment was significantly increased (p<0.001) as compared to control subjects (49.4±8.2 vs. 11.3±6.4). Internal radiation absorbed doses estimated for the 15 patients were 1.6±0.3Gy in this external irradiation study. The frequency of micronuclei post-administration of I-131-MIBG gradually decreased to near baseline (i.e., pre-therapy) levels by 2years. The relatively low frequency of lymphocyte micronuclei induced by I-131-MIBG in vivo and reversal of the increasing frequency of lymphocyte micronuclei after therapy suggest that the short-term non-stochastic damage induced by this therapy with 7.4GBq of I-131-MIBG in pheochromocytoma or ganglioneuroma patients is limited and reversible.

Association of elevated frequency of micronuclei in peripheral blood lymphocytes of type 2 diabetes patients with nephropathy complications.

The increasing incidence of type 2 diabetes mellitus globally has increased the incidence of diabetes-associated complications such as nephropathy. DNA damage induced by oxidative stress might be one of the important mechanisms in the pathogenesis of diabetic complications. Two hundred Iranian individuals with the conditions of type 2 diabetes, diabetic nephropathy and nephropathy patients with no sign of diabetes and normal unaffected sex- and age-matched controls (50 in each group) were enrolled in the study. The background and the net levels of micronucleus (MN) formation as well as other cellular damages induced after in vitro treatment with 25 µg/ml of bleomycin (BLM) were evaluated using cytokinesis block MNs cytome assay (CBMN cyt) in peripheral blood lymphocytes. The background and net BLM-induced levels of MNs were significantly higher in all patient groups compared with the control (P < 0.01, P < 0.001, respectively). The frequency of MNs was significantly higher in those patients with prior incidence of nephropathy than those without. A positive association was observed between basal and net MN frequency among study groups and also between net genetic damages and serum creatinine value and duration of diabetes. The rate of basal and net apoptosis was significantly higher in patients with hyperglycemia. Our results indicate that increased genomic instability expressed as MNs is associated with nephropathy in all pathological stages. Therefore, implementation of MN assay in clinical level may potentially enhance the quality of management of patients with diabetes and its complications such as nephropathy.

Cytogenetic damage of radiotherapy in long-term head and neck cancer survivors

Purpose: To evaluate cytogenetic damage of radiotherapy (RT) and chemoradiotherapy (CRT) in long-term head and neck cancer survivors.Materials and methods: This study included 20 patients treated with RT (10 patients) or CRT (10 patients) for head and neck cancer. Nine healthy volunteers were included as control subjects. Cytochalasin B-blocked micronucleus (CBMN) assay was used to evaluate cytogenetic damage. To evaluate micronucleus (MN) by CBMN, the venous blood samples were drawn median 68 months (range 60–239 months) after the completion of treatment (RT or CRT) for head and neck cancer.Results: Nuclear division index (NDI) and number of MN in mononuclear and binuclear lymphocytes were significantly higher in patients with head and neck cancer than in control subjects [1.19 (1.08–1.47) vs. 1.07 (1.04–1.14), p < 0.001; 11.0 (2.0–22.0) vs. 1.0 (0–3.0), p < 0.001 and 15.0 (5.0–45.0) vs. 9.0 (2.0–15.0), p = 0.020, respectively]. NDI and number of MN in mononuclear lymphocytes were significantly lower in control subjects compared patients received CRT and those received only RT, but there was no significant difference between patients received CRT and those received only RT. Number of MN in binuclear lymphocytes was significantly lower in control subjects compared to patients received CRT, but there was no significant difference between control subjects and those received only RT. Also there was no significant difference between patients received CRT and those received only RT in terms of number of MN in binuclear lymphocytes.Conclusions: MN frequency of mononuclear and binuclear lymphocytes in medical follow-up of patients with head and neck cancer after RT could be important in evaluating cytogenetic damage of RT. However, further investigations are needed to provide quantitative correlations between MN yields and the clinical features in post-radiotherapy period.

A systematic review of the association between occupational exposure to formaldehyde and effects on chromosomal DNA damage measured using the cytokinesis-block micronucleus assay in lymphocytes.

Formaldehyde (FAL) is classified as a Class I carcinogen by the WHO International Agency for Research on Cancer. Therefore, there is a need to validate appropriate methods for detecting its genotoxic effects in vivo in humans. One of the most commonly used methods to measure the genotoxic effects of exposure to environmental chemicals is the lymphocyte cytokinesis-block micronucleus (L-CBMN assay). We performed a systematic review and statistical analysis of the results from all of the published studies in which the L-CBMN assay was used to measure the genotoxic effects of human exposure to FAL. The results of this systematic review indicated that the majority (62%) of the 21 investigations in the 17 published studies we examined showed significant increases in lymphocyte micronucleus (MN) frequency (a biomarker of chromosome breakage or loss), in exposed subjects relative to controls. We used a novel quality score tool to determine if the investigations adequately addressed known variables that affect MN frequency in lymphocytes and found that MN frequency was not explained by quality because there was no significant correlation between quality score and fold-change in MN frequency (R=0.008, P=0.97). The results of all of the studies (positive or negative), when combined together, indicated a highly significant doubling in lymphocyte MN frequency in those exposed to FAL relative to controls (P<0.0001). These observations, together with a significant positive correlation between L-CBMN assay MN frequency and FAL air concentration (R=0.529, P=0.017) indicate the suitability of this method to measure in vivo genotoxicity of FAL. Furthermore, fold-increase in lymphocyte MN frequency in the exposed subjects relative to controls was strongly positively correlated with the duration of FAL exposure (R=0.779, P<0.0001) suggesting the need to better understand the potential for cumulative genomic instability induced by chronic exposures to FAL.

DOSE-RESPONSE STUDY USING MICRONUCLEUS CYTOME ASSAY: A TOOL FOR BIODOSIMETRY APPLICATION.

The present study is aimed at obtaining in vitro dose-response data for the induction of micronucleus (MN) and nucleoplasmic bridges (NPBs) in human lymphocytes using 60Co-gamma rays and 8 MeV pulsed electron beam. An attempt was made to validate the possibility of applying NPBs as new biodosimetry endpoint in the dose range of 0-6 Gy. A total of 1000 binucleated cells (BNCs) per dose point were evaluated for the frequency of MN and NPBs. From the study, it is clear that the dose-response increase of MN and NPBs is linear quadratic in nature. The study provides linear and quadratic parameter for biodosimetry application. The relative biological effectiveness value of the 8 MeV electron beam was estimated using slope values and is found to be 1.18 ± 0.01 for MN/BNCs, 1.27 ± 0.02 for the fraction of BNCs with MN, 1.16 ± 0.13 for MN/(BNCs with MN) and 1.09±0.01 for NPBs.

DNA double-strand breaks and micronuclei in human blood lymphocytes after repeated whole body exposures to 7T Magnetic Resonance Imaging

PurposeTo examine the extent of genetic damage, assessed from deoxyribonucleic acid (DNA) double-strand breaks (DSBs) and micronuclei (MN) in peripheral blood mononuclear cells obtained from individuals repeatedly exposed to 7T Magnetic Resonance Imaging (MRI). Materials and methodsThe study protocol was approved by the local ethics committee. Informed consent was obtained from 22 healthy, non-smoking, non-alcoholic male individuals, who had never undergone radio-/chemo-therapy, scintigraphy, and had not undergone X-ray examination one year prior blood withdrawal. Eleven participants were repeatedly exposed to 7T and 3T MRI while working with/around scanners or frequently participating as 7T and lower field MRI research subjects (mean age 34±7years). The other half was never exposed to 7T or lower field MRI and served as controls (mean age 33±9years).The damage in lymphocytes was assessed using anti-γH2AX immunofluorescence staining of DNA DSBs and by quantification of MN. Isolated cells were further exposed in vitro to 7T MRI either alone or in the presence of the DNA damaging drug etoposide, to determine if there is any additional combined effect. The kinetics of DNA damage repair were examined. ResultsThe mean base-level of γH2AX foci/cell and incidence of MN between repeatedly exposed and control group were not significantly different (P=0.618 and P=0.535, respectively). The additional in vitro exposure of cells to 7T MRI had no significant impact on MN frequencies and γH2AX foci at 1, 20 and 72h after exposure. ConclusionFrequently repeated 7T MRI exposure did not result in a detectable increase in genotoxicity indices and alterations of DNA repair kinetics.

Peripheral blood lymphocyte micronucleus frequencies in men from areas of Kerala, India, with high vs normal levels of natural background ionizing radiation

We have measured the frequencies of micronuclei (MN) in adult male individuals living in areas of the Kerala coast, southwest India, with either high (HLNRA, >1.5mGy/year) or normal levels of natural ionizing radiation (NLNRA, ≤1.5mGy/year). Blood samples were obtained from 141 individuals, 94 from HLNRA and 47 from NLNRA, aged 18–72, and were subjected to the cytokinesis-block micronucleus (CBMN) assay. An average of 1835 binucleated (BN) cells per individual were scored. The overall frequency of MN (mean±SD) was 11.7±6.7 per 1000 BN cells. The frequencies of MN in the HLNRA (11.7±6.6) and NLNRA (11.6±6.7) were not statistically significantly different (P=0.59). However, a statistically significant (P<0.001) age-dependent increase in MN frequency was observed among individuals from both HLNRA and NLNRA. No natural background radiation dose-dependent increase in MN frequency was seen. MN frequency was not influenced by tobacco smoking or chewing but it was increased among individuals consuming alcohol. Chronic low-dose radiation in the Kerala coast did not have a significant effect on MN frequency among adult men.

Size of silver nanoparticles determines proliferation ability of human circulating lymphocytes in vitro.

In this work we present biological effects of silver nanoparticles (AgNPs) synthesized by picosecond laser ablation of silver in deionized water. We examined induction of chromosomal aberrations, lymphocyte micronuclei, appearance and recovery of double strand breaks (DSBs) of DNA, cell proliferation potential, concentration of lipid peroxidation products and insulin-like growth factor 1 (ILGF-1). We found that AgNPs sized from 3 nm to 8 nm induce cell cytostasis, which is accompanied with its clastogenic action on DNA, while AgNPs, sized 2 nm behaves contrary stimulating cell proliferation by enhancing ILGF-1 concentration.

Biomonitoring of tunnel workers exposed to heavy air pollution in Rio de Janeiro, Brazil

Epidemiological studies found an increased risk of cancers in occupants exposed to traffic air pollution. Fine particulate matter is toxic, can enter into the respiratory tract and circulatory system, and can adsorb various substances, such as polycyclic aromatic hydrocarbons and its amino, alkyl, and nitro derivates. The study was carried out with Reboucas tunnel workers (exposed group) and 11 healthy men (control group). This tunnel is very representative of Brazilian cities and the biggest tunnel of the city of Rio de Janeiro. Samples of buccal mucosa cells and peripheral blood were evaluated using micronucleus assay. Urine samples were used to estimate the concentration of 1-hydroxyprene (1-HOP) and 2-naphthol (2-NAP). A significantly higher frequency of micronucleus in buccal cells and binucleated lymphocytes was observed for the exposed workers than for the control group. Higher concentrations of 1-HOP and 2-NAP were detected in the exposure group. In conclusion, damage to the genetic material and the high concentrations of metabolites of polycyclic aromatic hydrocarbons detected in the biological samples taken from control group can be related to daily exposure to pollutants.

In vitro RABiT measurement of dose rate effects on radiation induction of micronuclei in human peripheral blood lymphocytes.

Developing new methods for radiation biodosimetry has been identified as a high-priority need in case of a radiological accident or nuclear terrorist attacks. A large-scale radiological incident would result in an immediate critical need to assess the radiation doses received by thousands of individuals. Casualties will be exposed to different doses and dose rates due to their geographical position and sheltering conditions, and dose rate is one of the principal factors that determine the biological consequences of a given absorbed dose. In these scenarios, high-throughput platforms are required to identify the biological dose in a large number of exposed individuals for clinical monitoring and medical treatment. The Rapid Automated Biodosimetry Tool (RABiT) is designed to be completely automated from the input of blood sample into the machine to the output of a dose estimate. The primary goal of this paper was to quantify the dose rate effects for RABiT-measured micronuclei in vitro in human lymphocytes. Blood samples from healthy volunteers were exposed in vitro to different doses of X-rays to acute and protracted doses over a period up to 24 h. The acute dose was delivered at ~1.03 Gy/min and the low dose rate exposure at ~0.31 Gy/min. The results showed that the yield of micronuclei decreases with decreasing dose rate starting at 2 Gy, whereas response was indistinguishable from that of acute exposure in the low dose region, up to 0.5 Gy. The results showed a linear-quadratic dose-response relationship for the occurrence of micronuclei for the acute exposure and a linear dose-response relationship for the low dose rate exposure.