Analysis of sister chromatid exchange, micronucleus and chromosomal aberration frequencies in rodents exposed to mosquito coil smoke by inhalation route

Mosquito coil smoke emitting from a mosquito repellent, was tested for its mutagenic effect in bone marrow cells from mouse and rat after 4 h acute inhalation exposure. Coil smoke with suspended particulate concentrations of 99–129 mg/m³, significantly elevated the frequencies of sister chromatid exchanges in bone marrow cells and micronuclei in polychromatic erythrocytes. Analysis of chromosomal aberrations in metaphases also revealed a significantly higher incidence of chromosomal aberration frequency in exposed rats and mice.     

Sister chromatid exchanges and micronuclei formations induced by sorbic acid and sorbic acid-nitrite in vivo in mice

The in vivo induction of sister chromatid exchanges and micronuclei formations by acute treatment with different concentrations of sorbic acid and by nitrite, individually and in combination, was studied in bone marrow cells of mice. A significant increase in the frequency of sister chromatid exchanges was only observed with the three higher concentrations of sorbic acid when compared to a distilled water control. Sodium nitrite produced a significant increase at all doses tested. A combination of half the concentration of sorbic acid and of sodium nitrite gave an additive effect over that of sorbic acid or sodium nitrite alone. In the micronucleus assay, the highest dose of sorbic acid (150 mg/kg body weight) produced a significant increase in micronuclei formations compared to the distilled water control. Sodium nitrite alone induced significant numbers of micronuclei at all concentrations tested when compared to the negative control. However, a combination of half the concentration of sorbic acid and of sodium nitrite gave synergistic effects which could possibly be ascribed to the formation of certain genotoxic compounds in vivo.     

Mutagenicity testing of doxylamine succinate, an antinauseant drug

Doxylamine succinate (DA), a compound which was formerly used as an antinauseant during pregnancy, showed no substantial mutagenicity in mouse embryos following transplacental exposure. A small dose-dependent induction of chromosomal aberrations was found in mouse embryos on day 11 of gestation. No induction of sister chromatid exchanges (SCE) was found in embryos on day 11 of gestation. A micronucleus test with fetal blood on day 17 of gestation was negative. Additionally, DA was negative in Chinese hamster bone marrow in vivo (micronuclei) and in human lymphocyte cultures in vitro (SCE).     

Genotoxicity study in lymphocytes of offset printing workers

The potential cytogenetic damage in offset printing workers was evaluated using sister chromatid exchanges (SCEs), chromosome aberrations (CAs) and micronuclei (MN) as biomarkers in peripheral lymphocytes of 26 volunteers (14 workers, 12 controls). The CA, SCE and MN frequency of offset printing workers was significantly higher than in their controls. The replication index (RI) was not affected while the mitotic index (MI) was affected most in the workers. It can be concluded from this study that chronic occupational exposure to printing dyes and thinner may lead to a slightly increased risk of genetic damage among offset printing workers.     

In vivo genotoxic effects of smoking and occupational lead exposure in printing press workers

The objective of the present study was to evaluate the genotoxicity of a combination exposure to lead and smoking in workers from the printing industry and also to examine the possible interaction between the two agents. Individuals were classified into 4 different groups: control group, lead-exposed group, smokers and the double-exposure group. Chromosomal analysis was carried out according to conventional methods. Our preliminary study shows that lead-exposed individuals had a significantly increased frequency of sister chromatid exchanges. Further, double exposure to smoking and lead inhibits mitosis.     

Effects on mouse embryos of in utero exposure to saccharin: teratogenic and chromosome effects

For teratogenesis studies, pregnant ICR albino mice were administered saccharin by three routes and at three different doses by each route as follows: Intraperitoneal injection of 500, 1,000, or 2,000 mg/kg saccharin on day 10 of gestation; intragastric tube delivery of 5,10, or 25 mg/kg/day of saccharin on days 5–15 of gestation; and as drinking water containing a 5, 10, or 20% solution of saccharin from day 0 through day 17. Appropriate controls were used for each set. No increase in either resorptions or malformations was found in mouse embryos whose dams had received saccharin by any of the three routes.For chromosome studies, saccharin was administered IP to pregnant ICR albino mice on day 10 of gestation as either a 1,000 mg/kg or 2,000 mg/kg dose. To demonstrate sister chromatid exchanges (SCE), bromodeoxyuridine was administered as 16 consecutive half-hourly doses of 25 mg/kg during the 8 h prior to saccharin injection. In addition, one group received two doses of BrdU and 2,000 mg/kg saccharin 8 h apart to demonstrate SCE frequency following exposure to saccharin for two cell cycles. The mice were given colchicine (4 mg/kg) 6 h after the final injection and killed 2 h later. Embryonic cell suspensions and metaphase spreads were prepared by routine methods. Metaphase spreads were examined for breaks or gaps (after Giemsa staining), for G-banding (using the ASG technique), for C-banding (using Giemsa staining after exposure to 0.07 N NaOH and incubation in 2x SSC at 60° C), and for SCE by the Hoechst-Giemsa method. Fifty metaphase spreads were counted for each experimental condition. There were no increases in gaps or breaks, in sister chromatid exchanges, or in either G-band or C-band lateral asymmetries in the cells of mouse embryos exposed to saccharin in utero. The chromosomes of the 10-day mouse embryo have been shown to be a very sensitive system for evaluation of mutagenic and putative teratogenic agents. The absence of a mutagenic effect of saccharin in this system is consistent with the absence of any teratogenic effect.     

Investigation of coffee in sister chromatid exchange and micronucleus tests in vivo

Administration of a single oral dose of instant coffee to Chinese hamsters at levels up to 2.5 g/kg body weight did not increase the frequency of sister chromatid exchanges. Furthermore, five consecutive daily oral doses of instant coffee given to Swiss OF-1 mice up to 3 g/kg/day did not induce increases in micronuclei above spontaneous levels. Similarly, no effect was observed in the micronucleus test after mice received two oral doses of coffee aroma of up to 50 ml/kg.     

Cytogenetic monitoring of cardiology unit hospital workers exposed to Doppler ultrasound

We studied the effects of ultrasound on the peripheral blood lymphocytes of medical personnel from a cardiology unit working with colour Doppler ultrasonic equipment. Cytogenetic risks from ultrasound exposure were assessed by analysis of chromosome aberrations, sister chromatid exchanges (SCE), study of cell-cycle kinetics and micronucleus assay. We found significant increases (P < 0.001) in the total number of chromosome aberrations, mainly due to chromatid breaks and acentric fragments, increases in the total number of micronuclei and SCE and disturbances in cell-cycle kinetics in the exposed group compared to the control. In spite of their limitations, the results of the present investigation indicate that individuals occupationally exposed to ultrasound may experience an increased genotoxic risk and strongly emphasize the need for more research into the nature and extent of the biological consequences to medical personnel working with Doppler ultrasound.     

Analysis of sister chromatid exchange and micronuclei in peripheral blood lymphocytes of nurses handling cytostatic drugs.

The genotoxic effect of occupational exposure of 20 nurses who handled cytostatic drugs in medical oncology and haematology units was evaluated by micronucleus and sister chromatid exchange test. The duration of employment in the units and of exposure to cytostatics ranged from 1 to 31 years. The exposed nurses manifested an increase in cells with micronuclei as compared to the control group (P < 0.05). Nurses exposed to cytostatic drugs for 20-31 years showed a higher frequency of micronuclei (P < 0.05), whereas there was no difference in frequencies between the control group and the group exposed for 1-14 years (P > 0.05). The influence of the exposure period proved to be a significant parameter for the micronucleus test. No statistically significant differences were observed in sister chromatid exchange (P > 0.05).     

Effects of orally administered antioxidants on micronuclei and sister chromatid exchange frequency in workers professionally exposed to antineoplastic agents

The widespread use of antineoplastic drugs in cancer treatment increased concern about possible hazard to workers involved in the preparation and administration of these drugs. In the present study, the effects of commercial antioxidative drug Oligogal Se® on genome protection were analyzed in 15 nurses handling the antineoplastic drugs at the Oncology Department in comparison to twenty healthy volunteers. The nurses took antioxidant mixture Oligogal Se®, consisting of vitamins C, E, A and selenium, one capsule per day, over a period of 6 months. Genome damage was measured in peripheral blood lymphocytes by usage of sister chromatid exchange test and the cytokinesis-block micronuclei test. The frequency of sister chromatid exchange (SCE) and micronuclei (MN) in the exposed group was significantly higher when compared to the control group (SCE, p < 0.05; MN, p < 0.01 respectively). After antioxidant supplementation, the frequency of sister chromatid exchange and micronuclei decreased (p < 0.05) when compared with the values from the beginning of the study, but were still above the values of the control group. The effects of confounding factors such as cigarette smoking and cytostatics exposure time were also evaluated. The data indicated that Oligogal Se® contributed to the decreasing of genome damages in workers handling the cytostatics.     

Different effects on hemesynthesis in male and female rabbits treated with lead acetate

The feasibility of an animal model was investigated to study the mechanisms underlying the difference in response to inorganic lead exposure between males and females, as shown in the different increase of zincprotoporphyrin (ZPP) in blood concentrations. Groups of rabbits of both sexes received s.c. injections of 0.25 (L) or 0.50 (H) mg lead acetate/kg b.w. or a control solution three times a week during 14 weeks. A steep increase of blood lead (PbB) was found in the first 4 weeks of exposure; in subsequent weeks PbB leveled off. In the L-group PbB increased to 775–1387 /1 rbc and in the H-group to 892–1522 g/l rbc. In female rabbits ZPP increased earlier than in males; the relative increase of ZPP was stronger in female rabbits, particularly in the H-group. No effect on Hb, Ht and body weight was observed. The response to lead in female and male rabbits is very similar to that observed in humans.     

Evaluation of genotoxic risk of handling cytostatic drugs in clinical pharmacy practice

The genotoxic risk of handling antineoplastic drugs was evaluated in fifteen women preparing chemotherapeutics in the Pharmacy Department of the University Hospital Maastricht. Twenty nurses of the same hospital, who were not exposed to cytostatics, acted as controls. Endogenous exposure to antineoplastic drugs was assessed by determination of urine mutagenicity, as well as by analysis of urinary methotrexate levels. As genotoxicological end-points, sister chromatid exchanges and hypoxanthine guanine phosphoribosyl transferase locus point mutations were studied in peripheral lymphocytes obtained via venous puncture. No differences in urine mutagenic activity, in sister chromatid exchange frequencies and in hypoxanthine guanine phosphoribosyl transferase point mutation frequencies between exposed and non-exposed groups were detected. Higher sister chromatid exchange frequency was observed in smokers as compared to non-smokers.     

Chromosome damage in workers in cigarette manufacturing industry

To investigate whether occupational exposure to tobacco dust is genotoxic, a group of employees in a tobacco factory was tested for structural chromosome aberrations (CA), cytokinesis-block micronucleus assay (CBMN) and sister chromatid exchanges (SCE) that are well established as indicators of early biological effects. The study group consisted of 40 tobacco workers and an equal number of matched controls. The results obtained in the exposed group showed a significant increase in chromosome aberrations (R=0.26), micronucleus frequency (R=0.56) and in sister chromatid exchanges (R=0.75), which was additionally influenced by smoking. A significant increase in high frequency cells (HFC) in the exposed group was also observed. Like the SCE frequency, the HFC frequency increased significantly in smokers of the control and exposed smokers. The study indicates that occupational exposure to tobacco dust induces genome damage. A higher risk was observed in women. The micronucleus frequency and sister chromatid exchange tests seem to be more reliable indicators of genome damage than chromosome aberrations in monitoring chronically exposed subjects.     

Chromosomal damage and atherosclerosis. A protective effect from simvastatin

In uremic patients, the frequency of sister chromatid exchanges appears markedly higher than in the general population. Statins are well known for their pleiotropic effects, which are independent of any reduction in cholesterol circulating levels. The aim of the present study was to determine the effects of exposure to escalating doses of simvastatin on the sister chromatid exchange rate in cultured lymphocytes in order to identify the influence of statin on genomic damage. Peripheral lymphocytic samples for culture were obtained from 25 healthy volunteers, 20 patients with documented carotid atherosclerosis and 30 atherosclerotic patients on maintenance regular acetate-free biofiltration. Hemodialyzed patients had a greater percentage of high frequency cells (50%) than healthy controls (3%) and a significantly higher average number of sister chromatid (9.82+/-2.1 vs. 4.65+/-2.18). The subgroup of hemodialyzed patients with high plaque score values was characterized by significantly greater values for both sister chromatid exchanges rate and high frequency cells percentage. Our findings demonstrate that there is an association between sister chromatid exchanges and high frequency cells rate and atherosclerosis in acetate-free biofiltration patients. In cultures with added simvastatin, high frequency cells percentages and mean sister chromatid exchanges levels were significantly lower than in cultures with an added vehicle alone, the reduction occurring in a dose-dependent fashion, above all in cultures from end stage renal disease patients. The findings, moreover, demonstrate new effects of simvastatin, which appeared to mitigate the expression of genomic damage in our model. However, it is not yet clear whether this effect is due to the prevention of genomic damage or to the potentiation of the DNA repair capacity. Statins may therefore have an anti-atherogenic action partly ascribable to their ability to provide protection against the development of atherosclerotic plaque.     

Assessment of genome damage in a population of Croatian workers employed in pesticide production by chromosomal aberration analysis,micronucleus assay and Comet assay

The widespread use of pesticides suggests that the evaluation of their genotoxicity should be extended using the different assays available. In the present study we used two standard cytogenetic methods (chromosomal aberration analysis and micronucleus assay) and the Comet assay as a relatively new and powerful technique. The study included 10 workers occupationally exposed to a complex mixture of pesticides (atrazine, alachlor, cyanazine, 2,4-dichlorophenoxyacetic acid, malathion) during their production and 20 control subjects with no history of exposure to any physical or chemical agents. For the chromosomal aberration analysis, whole blood was cultivated for 48 h, whereas for the micronucleus assay, whole blood was cultivated for 72 h. For the comet assay whole blood was embedded in agarose on a microscope slide, lysed with detergent, denaturated and subjected to alkaline electrophoresis. Damage to DNA was evaluated by measuring tail length and calculating the tail moment. A significantly increased number of chromatid and chromosome breaks, as well as the presence of dicentric chromosomes and chromatid exchanges in exposed subjects compared with control subjects (P < 0.05), was found. There was also a statistically significant difference in frequency and distribution of micronuclei between the two groups examined. In the exposed subjects the Comet assay showed a statistically significant (P < 0.001) increase in DNA migration. Results suggest that long-term occupational exposure to pesticides could cause genome damage in somatic cells and therefore may represent a potential hazard to human health.     

Polymorphism of glutathione conjugation of methyl bromide,ethylene oxide and dichloromethane in human blood: Influence on the induction of sister chromatid exchanges (SCE) in lymphocytes

A hitherto unknown glutathione-S-transferase in human erythrocytes displays polymorphism: three quarters of the population (conjugators) possess, whereas one quarter (non-conjugators) lack this specific activity. A standard method for the identification of conjugators and non-conjugators with the use of methyl bromide and gas chromatography (head space technique) is described. Three substrates of the polymorphic enzyme, methyl bromide, ethylene oxide and dichloromethane (methylene chloride), were incubated in vitro with individual whole blood samples of conjugators and non-conjugators. All three substances led to a marked increase of sister chromatid exchanges (SCE) in the lymphocytes of the non-conjugators but not in those of conjugators. A protective effect of the glutathione-S-transferase activity in human erythrocytes for the cytogenetic toxicity of these chemicals in vitro is thus confirmed. Since the enzyme activity is not found in erythrocytes of laboratory animals, species extrapolations for risk assessment of methyl bromide, ethylene oxide and dichloromethane should be reconsidered.     

EFFECTS OF SUBCHRONIC INHALATION EXPOSURE OF RATS TO EMISSIONS FROM A DIESEL ENGINE BURNING SOYBEAN OIL-DERIVED BIODIESEL FUEL

There is increasing interest in diesel fuels derived from plant oils or animal fats ("biodiesel"), but little information on the toxicity of biodiesel emissions other than bacterial mutagenicity. F344 rats were exposed by inhalation 6 h/day, 5 days/wk for 13 wk to 1 of 3 dilutions of emissions from a diesel engine burning 100% soybean oil-derived fuel, or to clean air as controls. Whole emissions were diluted to nominal NO x concentrations of 5, 25, or 50 ppm, corresponding to approximately 0.04, 0.2, and 0.5 mg particles/m 3, respectively. Biologically significant, exposure-related effects were limited to the lung, were greater in females than in males, and were observed primarily at the highest exposure level. There was a dose-related increase in the numbers of alveolar macrophages and the numbers of particles in the macrophages, as expected from repeated exposure, but no neutrophil response even at the highest exposure level. The macrophage response was reduced 28 days after cessation of the exposure. Among the high-level females, the group mean lung weight/body weight ratio was increased, and minimal, multifocal bronchiolar metaplasia of alveolar ducts was observed in 4 of 30 rats. Lung weights were not significantly increased, and metaplasia of the alveolar ducts was not observed in males. An increase in particle-laden macrophages was the only exposure-related finding in lungs at the intermediate and low levels, with fewer macrophages and fewer particles per macrophage at the low level. Alveolar histiocytosis was observed in a few rats in both exposed and control groups. There were statistically significant, but minor and not consistently exposure-related, differences in body weight, nonpulmonary organ weights, serum chemistry, and glial fibrillary acidic protein in the brain. There were no significant exposure-related effects on survival, clinical signs, feed consumption, ocular toxicity, hematology, neurohistology, micronuclei in bone marrow, sister chromatid exchanges in peripheral blood lymphocytes, fertility, reproductive toxicity, or teratology. This study demonstrated modest adverse effects at the highest exposure level, and none other than the expected physiological macrophage response to repeated particle exposure at the intermediate level.     

Cytogenetic Observations After Meglumine Antimoniate Therapy for Visceral Leishmaniasis

Few data are available concerning the genotoxic effects of antimonial salts therapy in humans. A patient suffering from visceral leishmaniasis was treated for 15 days with a cumulative dose meglumine antimoniate 42.5 g. Peripheral blood lymphocytes sampled before treatment, 7 days later, and at the end of therapy (day 15) were examined for the presence of structural chromosome aberrations, sister chromatid exchanges (SCEs), and micronuclei in binucleated cells. The treatment resulted in an increase of binucleated cells carrying micronuclei, with no changes in chromosome structural aberrations or in mean SCE frequency. On the basis of these observations and of experimental results reported in the literature, we conclude that therapy with meglumine antimoniate apparently does not represent a mutagenic or carcinogenic risk to humans.     

Antigenotoxic effect of apigenin against mitomycin C induced genotoxic damage in mice bone marrow cells

The antigenotoxic effect of apigenin was studied against the genotoxic damage induced by mitomycin C on mouse bone marrow cells using sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs) as parameters. Apigenin was studied at three different doses i.e. 10, 20 and 40 mg/kg b.w. and was found to be non-genotoxic at all the above three doses. Mitomycin C at 2 mg/kg b.w. was given along with the 10, 20 and 40 mg/kg bw of apigenin. A significant decrease in SCEs and CAs was observed, suggesting a protective role of apigenin against the genotoxicity of mitomycin C on mice bone marrow cells.