Nuclear Division Index Research Articles

Anticlastogenic Effect in Human Lymphocytes by the Sodium Salt of 3,4-Secoisopimar-4(18),7,15-trien-3-oic Acid

The ability of the sodium salt of 3,4-secoisopimar-4(18),7,15-trien-3-oic acid (1), a diterpenoid obtained from Salvia cinnabarina, to inhibit the genotoxic effect of ethyl methanesulfonate (a clastogenic agent) and colcemid (an aneugenic agent), was studied using a micronucleus assay on cultured human lymphocytes. Cells were treated with 1 before (pretreatment), during (co-treatment), and after (post-treatment) treatment with the mutagens, in order to investigate the type of antimutagenic activity (desmutagenic or bioantimutagenic) manifested. In the range of concentrations tested (0.3-330 μM) 1 reduced significantly the frequency of micronuclei induced by ethyl methanesulfonate, in both pre- and co-treatment protocols (up to 74% and 70% of reduction, respectively), showing an anticlastogenic activity. Conversely, 1 did not inhibit the effect of colcemid in all treatments. The nuclear division index value of lymphocytes was not affected by treatment with 1, thus demonstrating that the anticlastogenic effect of 1 was not due to a cytotoxic effect. On the basis of the results obtained, it can be hypothesized that 1 exerts its anticlastogenic activity against ethyl methanesulfonate by a desmutagenic mechanism, possibly by chemical inactivation of the mutagen.

Evaluation of the genotoxicity and cytotoxicity in the general population in Turkey by use of the cytokinesis-block micronucleus cytome assay

The cytokinesis-block micronucleus cytome (CBMN-Cyt) assay was originally developed as an ideal system for measuring DNA damage, cytostasis and cytotoxicity. The objective of the present study is to simultaneously evaluate the background levels of micronuclei (MN), nucleoplasmic bridges (NPBs), nuclear buds (NBUDs), cell death (necrosis or apoptosis) and nuclear division index (NDI) in the peripheral blood lymphocytes of non-occupationally exposed, healthy subjects living in the city of Kayseri in Turkey. We used the CBMN-Cyt assay, taking into account factors – age, gender, and smoking habits – that might affect MN frequency and also other CBMN-Cyt assay parameters. Ninety-six healthy subjects (48 female and 48 male) were selected with ages varying between 21 and 60 years. The parameters, except for the number of binucleated (BN) cells with NPBs, showed no statistically significant difference between smokers and non-smokers. There were significant differences between female and male groups in MN frequency (higher in females) and in the number of NPBs (lower in females), while the other parameters were not significantly different between genders. The correlations between years of age and MN frequency, number of NPBs and the frequency of necrotic cells were statistically significant, while the correlations between the years of age and the other parameters were not. The results of the correlation analysis between years of smoking and MN frequency were positive, although no statistically significant correlation was found between the years of smoking and the other parameters. Among the smokers, no correlation was found either between the pack-years of smoking and the parameters assessed in this group. The results of the present study provide evidence of increasing MN frequency, number of NPBs and frequency of necrotic cells with increasing age in the peripheral blood lymphocytes of healthy individuals and influencing MN frequency and number of NPBs by gender.

Sunlight and vitamin D affect DNA damage, cell division and cell death in human lymphocytes: a cross-sectional study in South Australia

The ultraviolet (UV)-B spectrum in solar UV radiation is essential for stimulating the epidermal production of vitamin D but also damages DNA and causes cancer in exposed cells. We examined the role of solar UV in inducing DNA damage in blood lymphocytes and the possible modulation of this damage by serum 25-hydroxy vitamin D (25(OH)D) in 207 male and female participants from South Australia. Personal solar UV exposure was estimated from hours of outdoor exposure recalled at the time of blood collection for analysis of DNA damage in lymphocytes, using the cytokinesis-block micronucleus cytome (CBMN-cyt) assay and of serum 25(OH)D. We examined the association between solar UV exposure, serum 25(OH)D and DNA damage using multiple linear regression, with age, sex, body mass index and alcohol consumption as covariates. The frequency of cells with micronuclei (a biomarker of chromosome breakage or loss) increased with increasing sun exposure [% increase = 5.24; 95% confidence interval (CI): 0.35 to 10.37 P-value = 0.04] but cells with nucleoplasmic bridges (a biomarker of misrepair of DNA strand breaks or telomere end fusions) decreased (% increase = -8.38; 95% CI: -14.32 to -2.03 P-value = 0.01). There was also a fall in the nuclear division index (NDI) (% increase = -1.01; 95% CI: -2.00 to 0.00 P-value = 0.05), suggesting diminished mitogenic response and, possibly, immune suppression. There was no overall relationship between 25(OH)D and DNA damage. There were, however, weak modulating effects of 25(OH)D on the associations of solar UV exposure with micronucleus formation and with NDI (P-interaction = 0.03 and 0.05, respectively), where the increase in micronuclei and fall in NDI with increasing solar UV were greater at serum 25(OH)D levels <50 nmol/l. Thus, the influence of solar UV exposure in causing DNA damage or immune suppression in internal tissues may be stronger when vitamin D levels are low.

Choline and/or Folic Acid Deficiency is Associated with Genomic Damage and Cell Death in Human Lymphocytes In Vitro

Choline and folate are interrelated methyl donors. Previous studies showed that folate prevents genomic damage in human lymphocytes in vitro; however, the association between choline and human genomic stability is uncertain. To explore the genotoxicity, cytotoxicity, and cytostatic effects and possible interactions of choline and/or folate deficiency on the human genome, lymphocytes from 6 volunteers were cultured in 18 combinations of choline (CC) and folic acid (FA) media for 9 days. The genotoxicity was evaluated by micronuclei, nucleoplasmic bridges, and nuclear buds in the binucleated cell; the cytotoxicity indices included apoptosis and necrosis, and the cytostatic effects were indicated by nuclear division index (NDI). Across all choline concentrations, the frequencies of all biomarkers except NDI were diminished when FA concentration was more than or equal to 120 nmol/L. The frequencies of micronuclei, buds, and necrosis were significantly higher at lower levels of CC (0–6 μmol/L) compared with higher concentrations of CC (12–21.5 μmol/L) while maintaining the same FA concentration. We concluded that both choline and folate significantly impact genomic stability and cell death, although effects of folate were 2.5- to 6.2-fold greater, depending on the biomarker and dose. A combination of 12 μmol/L CC and 120 nmol/L FA appears to be optimal for genomic integrity in vitro.

In vitro evaluation of the protective effects of 4-thujanol against mitomycin-C and cyclophosphamide-induced genotoxic damage in human peripheral lymphocytes

4-Thujanol (sabinene hydrate), a bicyclic monoterpene alcohol, is found in the essential oils of many aromatic and medicinal plants and is widely used as a fragrance and flavouring agent in many different products. The aim of this study was to evaluate the protective effects of 4-thujanol against the genotoxic effects induced by mitomycin C (MMC) and cyclophosphamide (CP) in human lymphocytes, using the chromosome aberrations, sister chromatid exchanges, and micronucleus tests, in the absence and in the presence of S9 mix, respectively. The cells were treated with 0.25 µg/mL MMC and 28 µg/mL CP as alone and cotreated with 13 + 0.25, 26 + 0.25, and 52 + 0.25 µg/mL 4-thujanol + MMC and with 13 + 28, 26 + 28, and 52 + 28 µg/mL 4-thujanol + CP as a mixture. The present study showed that 4-thujanol was unable to reduce the genetic damage induced by MMC, in the absence of S9 mix. On the other hand, probably the metabolites of 4-thujanol act as an antagonist and markedly antagonize CP-induced genotoxicity, in the presence of S9 mix. In general, 4-thujanol + MMC and 4-thujanol + CP decreased the mitotic index, proliferation index and nuclear division index to the same extent or more than those of individual exposure of MMC or CP. In conclusion, 4-thujanol significantly reduced (p < 0.001) the genotoxic damage induced by CP but not MMC when compared with the respective positive control alone. We can suggest that 4-thujanol may improve the chemopreventive effects and may also reduce the harmful side effects of CP, which is widely used in chemotherapy against cancer, without reducing its antiproliferative activities.

Genotoxic and cytotoxic effects of doxycycline in cultured human peripheral blood lymphocytes

Doxycycline (DOX) is a broad-spectrum tetracycline antibiotic used in the treatment of many infections. In this study, the genotoxic and cytotoxic effects of DOX in cultured human peripheral blood lymphocytes were investigated by measuring chromosome aberrations (CAs), cytokinesis-block micronucleus (CBMN) assay, mitotic index (MI), and nuclear division index (NDI). Cultures were treated with DOX at three concentrations (2, 4, and 6 µg/mL) for 48 hours. Mitomycin C (MMC) was used as a positive control. All the tested concentrations of DOX for MI and the higher concentrations (4 and 6 µg/mL) for NDI significantly decreased mitotic activity. However, there are no significant differences between negative control and all the tested concentrations of DOX for CA and MN frequencies. In conclusion, our results indicate that DOX has a cytotoxic effect, but not a genotoxic effect, on human peripheral blood lymphocyte cultures. Further detailed studies, especially about the cell-cycle kinetics of DOX, are required to elucidate the decreases in dividing cells and make a possible risk assessment on cells of patients receiving therapy with this drug. Further, if the specific cytostatic and cytotoxic potential of DOX to different types of cancer cells is investigated in detail, it may also have been used as an antitumoral drug.

In vitro genotoxic perspective of Tamiflu

The aim of this study was to investigate the genotoxic and/or cytotoxic effects of Tamiflu, commercial form of the oseltamivir antiviral and most frequently prescribed for the treatment of influenza infections, on cultured human peripheral lymphocytes by using sister chromatid exchange (SCE), chromosomal aberration (CA), and cytokinesis-blocked micronucleus (CBMN) assays. Cells were treated with 0.5, 1, 2μg/mL oseltamivir, the Tamiflu capsule ingredient, for 24 or 48h in the absence or presence of an exogenous metabolic activation system (S9 mix). The test chemical did not demonstrate any genotoxic effect dose-dependently but it showed a weak cytotoxicity on cells in this study. On the other hand, some concentrations of Tamiflu (2μg/mL without S9 mix for 48h and 1μg/mL with S9 mix) induced SCE and also decreased significantly the proliferation index (PI) (48 h period) and the nuclear division index (NDI) (24h period) (P<0.05) in the absence of S9 mix. Considering the results, Tamiflu did not induce significant increases of CA or micronucleated cells in vitro in cultured peripheral blood lymphocytes under the treatment conditions used but weak SCE induction was observed. On the other hand, the weak cytotoxic effects observed disappeared in the cultures treated in presence of the S9 mix.

Chromosomal damage and polymorphisms of metabolic genes among 1, 3-butadiene-exposed workers in a matched study in China

1, 3-Butadiene (BD) is a high-efficiency carcinogen in rodents and was classified as a human carcinogen in 2008 by the International Agency for Research on Cancer. However, its ability to induce genetic damage and the influence of metabolic polymorphisms to such damage in humans are both controversial claims. This study was conducted to investigate the relationships between exposure to BD, the polymorphisms of metabolic genes and the chromosomal damage in 45 pairs of occupationally exposed workers in a BD product workshop and matched control workers in an administrative office and circulatory water workshop in China. Exposure to BD was evaluated by personal sampling and stationary sampling. Different chromosomal damage endpoints in peripheral blood lymphocytes were determined using the cytokinesis-blocked micronucleus (CBMN) cytome assay; polymorphisms of metabolic genes [cytochrome P450 2E1 (CYP2E1), glutathione S-transferases (GST) and microsomal epoxide hydrolase (mEH)] in BD-exposed group were detected by polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism analysis. The results show that the average BD measurements of the exposed group were significantly higher than those for the control group (a personal sampling and stationary sampling, respectively). The BD-exposed workers exhibited increased frequencies of micronuclei (MNi) (8.00 ± 3.78‰ versus 5.62 ± 2.41‰) and nucleoplasmic bridges (NPBs) (2.58 ± 2.79‰ versus 1.13 ± 1.34‰) and a decreased nuclear division index (2.20 ± 0.14 versus 2.35 ± 0.27) when compared subjects in the control group. Meanwhile, BD-exposed workers carrying CYP2E1 c1c2/c2c2 or mEH intermediate (I)/high (H) group had a significantly higher NPB frequency than those carrying CYP2E1 c1c1 [frequency ratio (FR) = 2.60, 95% confidence interval (CI) 1.72-3.93; P < 0.0001) or the mEH low(S) group (FR = 2.06, 95% CI% 1.17-3.62; P < 0.05), respectively. Our study suggests that MNi and NPB frequency in CBMN cytome assay could be potential genotoxic biomarkers for BD exposure in humans. The polymorphism of CYP2E1 and mEH could also affect the chromosomal instability of BD workers.

Micronucleus evaluation for determining the chromosomal breakages after radionuclide synovectomy in patients with hemophilia

To investigate the genotoxic effects of (90)Y and (186)Re in patients with hemophilia who were undergoing radionuclide synovectomy (RS) procedure in the last 3years. Nineteen patients were enrolled in the study. Most of the patients (n=17) were hemophilia-A (mean age 20.6±10.5years) and 18 patients (mean age 22.6±10.6years) with hemophilia who were not exposed to RS procedure were included in the study as control group. Most cases in the control group (n=13) were hemophilia-A. (90)Y for knee joints and (186)Re for elbow or ankle joints were used to perform RS in hemophilic patients. We studied the micronucleus (MN) test on peripheral blood lymphocytes as an indicator of radiation-induced cytogenetic damage and calculated nuclear division index. There was no significant difference between the patients with and without RS with respect to MN values. However, both values obtained in RS-exposed patients and control group were much elevated than values reported in literature from healthy controls. The mean MN values of patients below 20years old were much lower but not significant than those above 20years old. MN frequencies between (186)Re and (90)Y groups were also analyzed, and no significant difference was observed. Hemophilia patients who were treated with (186)Re showed higher levels of MN compared to patients treated with (90)Y although the difference was not significant. Radioisotope synovectomy (RS) seems to be a safe procedure not causing a significant genotoxic effect on hemophilic patients, however, further studies including larger series of patients are needed to better understand the effects of RS on patients' health.

The genotoxic and anti-genotoxic effects of Stachys petrokosmos leaf extract in human lymphocytes using microsomal fractions

The genotoxic and anti-genotoxic effects of Stachys petrokosmos leaf extracts (Sp) were investigated in human lymphocytes. The cells were treated with 1.5, 3.0 and 6.0μL/mL concentrations of Sp leaf extracts for 24 and 48h treatment periods in the absence and presence of metabolic activator (S9mix). In the absence of S9mix, Sp alone did not induce chromosome aberrations and formation of micronucleus while inducing the mean sister chromatid exchange at the highest concentration. In addition, Sp decreased the mutagenic effect of mitomycin-c. Sp alone showed a cytotoxic effect determined by a decrease in the proliferation index, mitotic index and nuclear division index. On the other hand a mixture of Sp and mitomycin-c resulted in a higher cytotoxic effect especially for 48h treatment period. In the presence of S9mix, Sp was not genotoxic and cytotoxic however, it showed an anti-genotoxic effect by decreasing the effects of cyclophosphamide.

A combination of the cytokinesis-block micronucleus cytome assay and centromeric identification for evaluation of the genotoxicity of dicamba

The purpose of this study was to further investigate the cytotoxic and genotoxic effects of dicamba and Banvel® employing the cytokinesis-block micronucleus cytome (CBMN-cyt) assay estimated by the analysis of the nuclear division index (NDI), the frequency of micronucleus (MN), nucleoplasmic bridges (NPBs), and nuclear buds (NBUDs). Besides, for mechanism of MN induction CREST anti-kinetochore antibody analysis was performed. The activities of both compounds were tested within the range of 50–500μg/ml on Chinese hamster ovary (CHO-K1) cells. Overall, dicamba and Banvel® produced a NDI dose-dependent decrease but the response was statistically significant only in cultures treated with Banvel® at a 100–500μg/ml concentration range. A dose-dependent induction of MN was observed after dicamba- and Banvel®-treatments within the 50–400μg/ml and 50–500μg/ml concentration-ranges, respectively. Induction of NPBs and NBUDs was significantly enhanced by both test compounds. The NPBs/MN ratio values found for dicamba and Banvel® were 0.04–0.11 and 0.05–0.18, respectively. Results clearly demonstrated that dicamba and Banvel® exerted both cyto- and genotoxic damage on CHO-K1 cells. Furthermore, the CBMN-cyt assay employed confirmed our previous investigations concerning the cellular and DNA damaging capabilities of dicamba and highlights that both clastogenic and aneugenic mechanisms are implicated in the MN induction.

The effects of 4-thujanol on chromosome aberrations, sister chromatid exchanges and micronucleus in human peripheral blood lymphocytes

4-Thujanol, a bicyclic monoterpene alcohol, is present in the essential oils of many medicinal and aromatic plants. It is commonly used as a fragrance and flavouring ingredient in a lot of different products. The potential genotoxic effects of 4-thujanol on human peripheral blood lymphocytes (PBLs) were investigated in vitro by the chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and micronucleus (MN) tests. The cells were treated with 13, 26 and 52μg/mL 4-thujanol in the presence and absence of a metabolic activator (S9 mix). 4-Thujanol induced CA (P<0.001) and MN formation (P<0.05) at all concentrations (13, 26 and 52μg/mL) in the presence and absence of the S9 mix without a concentration-dependent manner. However, the treatment of peripheral lymphocytes with 4-thujanol did not produce a statistical difference in the frequency of SCEs when compared with control group. Furthermore, this monoterpene did not significantly decrease the mitotic index (MI), proliferation index (PI), and nuclear division index (NDI). In conclusion, 4-thujanol had a significant clastogenic effect at the tested concentrations (13, 26 and 52μg/mL) for human PBLs. In addition, no cytotoxic and/or cytostatic effects were observed regardless of the concentrations used. This work presents the first report on genotoxic properties of 4-thujanol.

Micronucleus frequencies in peripheral blood lymphocytes of children with chronic kidney disease

One of the crucial adverse effects of chronic kidney disease (CKD) and its treatment is an elevated cancer risk. There are no data on cytogenetic effects in children with CKD or children undergoing dialysis or those who have received a transplant. In this study, cytogenetic effects in children with CKD in pre-dialysis (PreD) stage, on regular haemodialysis (HD) and transplanted (Tx) compared with a control group of healthy children has been investigated using the cytokinesis-blocked micronucleus (CBMN) assay and fluorescence in situ hybridisation (FISH) combined with CBMN (CBMN-FISH) in peripheral blood lymphocytes. The results revealed a significant increase (P < 0.001) in micronucleus (MN) frequencies [mean ± SD (n)] in the PreD, HD and Tx groups versus the control group [CBMN assay; 9.19 ± 2.61 (16), 9.07 ± 4.86 (15), 6.12 ± 5.33 (17) versus 1.60 ± 0.99 (20), respectively]. Moreover, centromere negative micronucleus (C- MN) and centromere positive micronucleus (C+ MN) frequencies were significantly higher in each subgroup children (PreD, HD and Tx) than in the control group (P < 0.01) although children in Tx group had lower C- MN frequencies than PreD and lower C+ MN frequencies than PreD and HD groups (P < 0.05). Additionally, MN frequencies in mononuclear cells, nucleoplasmic bridges and nuclear buds in binucleated cells were increased in children with CKD (P < 0.001, P < 0.001, P > 0.05, respectively). The nuclear division index significantly decreased in Tx group relative to the control, PreD and HD groups (P < 0.001). Associations between cytogenetic parameters and creatinine or blood urea nitrogen were found (P < 0.05). To provide longer and better life expectancy of children with CKD and treatment modes, further research is needed to better understand and avoid these effects.

The evaluation of the genotoxic and oxidative damage potentials ofUlothrix tenuissima(Kütz.)in vitro

Several alga species are known to produce a variety of toxic metabolites that pose a threat to aquatic organisms, animals and humans. Moreover, these metabolites have been thought to cause serious diseases including certain cancers and neurodegenerative disorders. On the other hand, Ulothrix is a genus of filamentous green algae, generally found in fresh water and marine and abundantly available in some lakes and rivers of Turkey. To our best knowledge, no study has been performed to assess the genotoxic and biochemical effects of U. tenuissima on cultured human blood cells. Therefore, in order to determine clastogenic or aneugenic effects of aqueous alga extracts the micronucleus assay was carried out. Nuclear division index (NDI) in peripheral lymphocytes was also analyzed for cytotoxicity evaluations. In addition, biochemical parameters (total antioxidant capacity (TAC) and total oxidative stress (TOS)) were examined to determine oxidative effects. For this aim, we obtained heparinized blood samples from three healthy persons. The alga samples were collected from Porsuk Pond in Hasankale (Erzurum, Turkey) in summer period of the year 2010. The aqueous extracts of this species were added to cultures at different concentrations (0 to 5000 ppm) for 72 h. Our results showed that this alga did not cause any statistically important changes in the rates of studied genotoxicity endpoint. But dose-dependent alterations were observed in TAC and TOS levels and NDI rates. In conclusion, U. tenuissima was found to be non-genotoxic but caused sterility at higher concentrations due to oxidative stress.

Evaluation of the genotoxicity and cytotoxicity of fexofenadine in cultured human peripheral blood lymphocytes

Fexofenadine (FXF) is a new non-sedating antihistamine used in the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria. Studies on FXF genotoxicity and cytotoxicity in cultured human peripheral blood lymphocytes have not been reported so far. Therefore, the present study is the first report investigating the genotoxic and cytotoxic effects of FXF in cultured human peripheral blood lymphocytes in vitro. Cultures were treated with FXF at three concentrations (50, 100 and 150μg/ml) for 24 and 48h. Endpoints analyzed included: mitotic index (MI), nuclear division index (NDI), chromosomal aberrations (CA) and micronucleus (MN) assay. Mitomycin C (MMC) was used as a positive control. The results of CA and MN assays showed that FXF was not genotoxic at all the concentrations tested, meanwhile MI and NDI results showed dose-dependent decrease and significant differences were found for at least one concentration. In conclusion, the results of this study suggest that FXF has a cytotoxic effect but not genotoxic effect on human peripheral blood lymphocyte cultures. Further cytogenetic studies, especially about the cell cycle kinetics of FXF are required to elucidate the decreases in dividing cells, and biomonitoring studies should also be conducted with patients receiving therapy with this drug.

Age-related changes in genomic stability of horses

Recently, the old horse has been proposed as a model to study telomere-dependent senescence, immunosenescence and inflamm-aging. In the present paper, we used 80 Hucul and Anglo-Arabian horses divided into 3 age groups (juvenile, adult, old) to evaluate age-dependent changes at the genomic and DNA level and in cell proliferative potential. The level of positive TUNEL cells (both apoptotic and with DNA fragmentation), oxidative DNA damage (8-oxoG immunostaining), sister chromatid exchange and bleomycin-induced chromatid breaks were significantly increased in the combined old group compared to the combined adult group. We observed a negative correlation between micronuclei formation and age, which may be associated with damaged cells undergoing apoptosis, rather than expressing micronuclei. We were unable to show any significant changes in the nuclear division index value, which reflects the proliferative status of the viable cell fraction during aging. Here, we show that breed-independent and age-associated changes in genomic stability may contribute, at least in part, to the aging process in the horse.

CYTOKINESIS-BLOCK MICRONUCLEUS (CBMN) ASSAY/CBMN CYTOME ASSAY IN HUMAN LYMPHOCYTES AFTER IN VITRO IRRADIATION AND ITS USE IN BIODOSIMETRY

Summary Aim: Cytokinesis-block micronucleus (CBMN) assay and its comprehensive variant CBMN cytome assay are cytogenetic methods. CBMN is based on assessment of micronuclei in nucleated cells that have completed only one nuclear division. Besides micronuclei, CBMN cytome assay analyzes additional genotoxic (nucleoplasmic bridges and nuclear buds), cytostatic (nuclear division index), and cytotoxic (amount of necrotic and apoptotic cells) parameters. The aim of this study is to evaluate these parameters in human blood lymphocytes after in vitro irradiation and to assess its contribution to biodosimetry. Material and methods: Human blood from 6 donors was in vitro irradiated by 0, 1, 2, 3, 4, or 5 Gy and cultivated for 72 hours. Blood lymphocytes were stimulated with phytohemagglutinin and their cytokinesis was blocked by cytochalasin B. After cultivation, cultures were hypotonically treated, dropped onto glass slides and stained with Giemsa. Slides were evaluated by microscope. Results: We observed significantly increased amount of micronuclei, nucleoplasmic bridges, and nuclear buds measured in binucleated cells, significantly increased amount of micronuclei measured in mononucleated cells and significantly decreased nuclear division index after irradiation by 1, 2, 3, 4, and 5 Gy. Amount of death cells (apoptotic and necrotic) significantly increased after irradiation by 4 and 5 Gy. Conclusion: Although all parameters assessed by CBMN cytome assay have biodosimetric potential, practically feasible is only evaluation of micronuclei in binucleated cells. This parameter was used to construct in vitro linear-quadratic dose-response calibration curve which could be used as a biodosimetric tool for triage of radiation casualties.

In vitro genotoxicity of rocuronium bromide in human peripheral lymphocytes

Rocuronium bromide (RB), an aminosteroid type neuromuscular blocking agent, acts by reducing or inhibiting the depolarising effect of acetylcholine on the terminal disc of the muscle cell. To our knowledge, there is no adequate information on the genotoxic effects of RB, up to now. In the present study, possible genotoxic effects of RB have been determined by means of sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) analyses in human peripheral blood lymphocytes. The human peripheral blood lymphocytes were exposed to three different concentrations of RB (60, 80 and 100μg/mL) for 24- and 48-h. In this study, RB increased the frequency of CAs, however, did not increase the frequency of SCEs. RB did not decrease the proliferation index (PI) and mitotic index (MI). Accordingly, RB increased the frequency of micronucleus (MN) but did not decrease the nuclear division index (NDI). Findings from this study suggest that rocuronium bromide is clastogenic but not cytotoxic to cultured human peripheral blood lymphocytes.

Occupational risk assessment of oxidative stress and genotoxicity in workers exposed to paints during a working week

Paints are complex mixtures of solvents and metals that can induce health damages in workers exposed to them. The aim of the present work was to evaluate possible oxidative and genotoxic effects in workers exposed to paints. Peripheral blood and buccal cell samples were collected from 33 workers exposed to paints and 29 non-exposed workers (controls) during an ordinary working week (Monday morning and Friday evening). Oxidative markers were assessed using thiobarbituric acid assay, carbonylated proteins, superoxide dismutase and catalase activities. Hippuric acid and delta-aminolevulinic acid were determined as biomarkers of toluene and lead exposure, respectively. Genotoxicity was measured through comet assay and micronucleus (MN) frequencies. The exposed group showed higher hippuric acid and delta-aminolevulinic acid levels (Friday samples) and lower superoxide dismutase activity (Monday samples) in relation to control group. DNA damage index (comet assay) was higher in the exposed group, both in Monday and Friday samples, compared to the control group. No differences were observed in frequency of micronuclei (MN) between the groups, either in lymphocytes or buccal cells. However, the exposed group presented an increase (Monday samples) in nuclear buds frequency in lymphocytes - a marker of gene amplification - as well as an increase in condensed chromatin in the buccal cells (Monday and Friday samples), suggesting induction of apoptosis. Furthermore, a decrease in the nuclear division index (Friday samples) was observed in the exposed group, indicating that paint exposure induces cytostatic effects in lymphocytes. The results suggest that individuals exposed to paints have increased levels of DNA damage.

Micronucleus test for determining genotoxic damage

Micronuclei (MN) are formed during mitosis and do not integrate in the main nucleus. They may arise from a whole lagging chromosome or an acentric chromosome fragment. An increase of MN frequency indicates genomic instability. The MN test is commonly used to determine the genotoxic effects of chemical and physical agents on somatic cells. It is applied to all types of cells reproducing by mitosis in vitro and in vivo, and it is easier and faster to perform than the chromosome aberration assay. With the development of the in vitro cytochalasin-B block method for detecting MN frequency in binuclear cells, its reliability and validity has been increased. At the same time, the test enables an estimation of cytotoxicity using the frequency of nuclear division index in in vitro studies, and the ratio between polychromatic erythrocytes and normochromatic erythrocytes in in vivo studies. Human beings and other species are exposed to a large number of chemical and physical factors in their environment. Therefore, the genotoxic studies about the adverse effects and potential risks of those factors gain importance exponentially. The MN test is a practical bio-monitoring test that provides an investigation tool on genotoxic and carcinogenic potentials and reliability of physical agents, drugs and all types of other chemical such as pollutants, food additives to which people are exposed daily, and it helps to predict and monitor the cancer risk. The MN technique, OZET Mikronukleus (MN)’lar hucrenin mitoz bolunmesi