Showing papers in "Mutation Research\/genetic Toxicology in 1995"
TL;DR: The literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts is reviewed, directing laboratories in the development of fish genotoxicity assays for water quality monitoring.
Abstract: Micronucleus assays with fish have been shown to be useful in vivo techniques for genotoxicity testing, and show potential for in situ monitoring of water quality In this paper, we review the literature on the clastogenic effects of chemical and physical agents on fish cells, with emphasis on the induction of micronuclei in teleosts Included in the review is a description of the mechanisms for formation of micronuclei in cells, and a summary of the various techniques that have been used for micronucleus analysis in fish This review is directed to assisting laboratories in the development of fish genotoxicity assays for water quality monitoring
701 citations
TL;DR: Results indicate that nicotine and its major metabolites are not genotoxic in the assays conducted.
Abstract: Nicotine is a naturally occurring alkaloid found primarily in members of the solanaceous plant family, which includes tobacco. Nicotine is rapidly absorbed by humans and then metabolized, primarily by cytochrome P450's. Studies on the genotoxic potential of these metabolites are limited. Nicotine and four of its major metabolites: cotinine, nicotine-N'-oxide, cotinine-N-oxide, and trans-3'-hydroxycotinine were evaluated for genotoxic potential in the Salmonella mutagenicity assay (strains TA98, TA100, TA1535, TA1537, and TA1538) at concentrations ranging from 0 to 1000 micrograms/plate and in the Chinese hamster ovary sister-chromatid exchange (SCE) assay at concentrations ranging from 0 to 1000 micrograms/ml. All assays were conducted with and without S9 metabolic activation. None of the five compounds increased the frequency of mutations or the frequency of SCEs. These results indicate that nicotine and its major metabolites are not genotoxic in the assays conducted.
103 citations
TL;DR: The results showed that the combination of ARA-C and HU substantially increased the level of MN in whole blood lymphocyte cultures, but it provided an excess of toxicity when further treatments, such as MNU, were performed.
Abstract: The cytokinesis blocked micronucleus assay is relatively insensitive to detect agents that predominantly induce excision repairable DNA lesions. However, it has been recently proposed that excision-repairable DNA lesions induced in G0/G1 phase can be converted to micronuclei by using inhibitors of the gap filling step of excision repair so that unfilled gaps are converted to double stranded breaks after S phase and micronuclei (MN) at completion of mitosis. As it has been recently demonstrated this process could be improved by combining cytosine arabinoside (ARA-C) and hydroxyurea (HU). In the present work, we have investigated the suitability of this new approach by studying its ability to detect excision repairable DNA lesions induced by 10 pesticides (alachlor, atrazine, cypermethrin, deltamethrin, fenpropathrin, fenvalerate, maleic hydrazide, paraquat, permethrin and trifluralin) and 3 well-known mutagenic agents (ethyl methane sulphonate, EMS; methylnitrosourea, MNU; and mytomicin C, MMC). Our results showed that the combination of ARA-C and HU substantially increased the level of MN in whole blood lymphocyte cultures, but it provided an excess of toxicity when further treatments, such as MNU, were performed. When ARA-C alone was used, the ARA/CBMN assay appeared to be highly sensitive and specific in detecting agents known to induce excision repairable DNA lesions. Thus, EMS and MNU but not MMC greatly induced DNA excision repair. On the other hand, alachlor, permethrin and, to a lesser extent, trifluralin and fenpropathrin also increased the ratio of excision repairable DNA lesions converted to MN. On the contrary, atrazine, cypermethrin, deltamethrin, fenvalerate, maleic hydrazide and paraquat did not induce excision repair.
98 citations
TL;DR: Both in the presence and absence of S9, quercetin appears to behave as a clastogenic agent in human lymphocytes inducing a significant majority of kinetochore-negative MN.
Abstract: Quercetin, a mutagenic flavonoid widely distributed in edible plants, was studied for the induction of micronuclei (MN). We have carried out the MN assay in bone marrow polychromatic erythrocytes in mice, in cytokinesis-blocked human lymphocytes and in cytokinesis-blocked V79 cells. MN assay in vitro was performed in the presence and in the absence of S9. To further extend the study, an antikinetochore antibody (CREST staining) was used to distinguish MN containing whole chromosomes (kinetochore positive) from those containing acentric fragments (kinetochore negative). When tested in vivo quercetin failed to induce micronuclei, a result which is in agreement with other published reports. When tested in vitro in V79 cells quercetin clearly induces micronuclei in the absence of S9 and also in the presence of S9 for the highest dose used. When tested in vitro in human lymphocytes quercetin shows a significant induction of micronuclei in the absence and in the presence of S9. The presence of S9 compared to its absence is not significant for any of the systems used. Both in the presence and absence of S9, quercetin appears to behave as a clastogenic agent in human lymphocytes inducing a significant majority of kinetochore-negative MN.
96 citations
TL;DR: The absence of precise criteria for MN identification in mollusks and the identification of highly basophilic spherical inclusions in the cytoplasm of gill tissue hemocytes in oysters during viral infection are handicap for application of the micronuclei assay in the marine environment.
Abstract: The micronucleus (MN) test was performed in vivo and in vitro on the oyster Crassostrea gigas to evaluate the genotoxic effect of the marine environment. In vitro tests were carried out on adult and young (spat) specimens exposed to benzo[a]pyrene (BaP: 0.5, 5, 500 and 1000 μg.1−1) and an effluent (5, 50, 75 and 100%) of Seine Bay, one of the most highly contaminated sites in France. MN frequency observed after 48 h exposure to the two pollutants was much greater in adults than spats. A preliminary test of the genotoxic effect of BaP (0.05, 0.5, 1 and 500 μg·1−1,, cupric sulfate (10, 25, 50 and 100 μg·1−1) and a paper mill effluent (1, 3, 10 and 30 mg·1−1) was performed in C. gigas heart cells cultured for 6 days. Comparison of the MN assay with the C. gigas larva test showed the clastogenic action of BaP and the toxic effect of cupric sulfate on culture cells as well as the slighter toxic effect of paper mill effluent on spats. An in vivo study was conducted in an oyster-farming area contaminated by cadmium and copper. MN frequency was not very sensitive to a pollution gradient but showed high interindividual variability. The absence of precise criteria for MN identification in mollusks and the identification of highly basophilic spherical inclusions in the cytoplasm of gill tissue hemocytes in oysters during viral infection are handicap for application of the micronuclei assay in the marine environment. Another limitation of the assay is the particularly onerous requirement for manual observation. Optimization of the assay by automated analysis is necessary but can only be achieved if cytologic preparations are of good quality.
95 citations
TL;DR: It is concluded that, whenever possible, samples should be treated by the direct method in different volumes to prevent the loss of genotoxic substances.
Abstract: The genotoxicity of river water samples was evaluated by the Salmonella mutagenicity assay and by the microscreen phage-induction assay. Different processes of sample treatment were compared using the following assays: different volumes of a non-concentrated sample (direct method); concentrated sample fractionated into portions with acid, basic and neutral activity (liquid-liquid extraction method); sample submitted to extraction of volatile substances (volatile extraction method). Samples that were positive to the Salmonella assay by the direct concentration method lost this activity after liquid-liquid extraction. This difference was related to the loss of substances that volatilize during the extraction process. The study of volatile product concentrates confirmed the role of these compounds in inducing activity present in some samples. The microscreen phage-induction assay proved to be a good screening assay for genotoxic compounds present in small concentration in environmental samples. We conclude that, whenever possible, samples should be treated by the direct method in different volumes to prevent the loss of genotoxic substances.
83 citations
TL;DR: It is found that during the period of major exposure, the group of agricultural workers showed a significant increase in the frequency of CA, mainly of chromatid-type, when compared to the unexposed control group, which could indicate that the frequency is related to the intensity of the pesticide exposure, and that CA have a relatively short life, recovering the control value a few months later.
Abstract: The induction of chromosomal aberrations (CA) was studied in the peripheral lymphocytes of 29 male agricultural workers occupationally exposed to several pesticides. To investigate possible exposure-related changes in the frequency of CA, a longitudinal study has been conducted. Two blood samples were taken from each individual: one in a period of high exposure (spring-summer) and the other in a period of lower exposure (autumn-winter). Simultaneously, two matched control groups constituted by 29 and 24 healthy men, without indication of exposure to pesticides, were analysed. During the period of major exposure, the group of agricultural workers showed a significant increase in the frequency of CA, mainly of chromatid-type, when compared to the unexposed control group; nevertheless, this increase in the expression of CA was not found in the period of minor exposure. This finding could indicate that the frequency of CA is related to the intensity of the pesticide exposure, and that CA have a relatively short-life, recovering the control value a few months later. In addition to the cytogenetic analysis, biochemical and haemotological blood parameters were also analysed and no significant variations were detected.
81 citations
TL;DR: Data indicate that the clam C. fluminea is provided with a P-glycoprotein-like element of the MDR-mechanism, that this system can be poisoned by chemosensitizers such as verapamil and STP, and the importance of the MXR modulators for the assessment of ecotoxicological effects of pollutants.
Abstract: The presence of a 'multixenobiotic resistance' [MXR] mechanism in gills of the freshwater clam Corbicula fluminea was investigated. Western blot analyses of membrane vesicles from gills, applying antibodies to vertebrate P170 multidrug resistance (MDR) protein, revealed a 135 kDa immunoreactive protein. Verapamil caused a reduction of 3H-vincristine (3H-VCR) binding onto vesicles from clam. Exposure of clams to 3H-VCR in the presence of verapamil or staurosporine (STP) enhanced the accumulation of 3H-VCR over control values. Furthermore, clams were exposed instead to VCR, to a model carcinogen, 2-acetylaminofluorene (AAF), to determine the verapamil- and STP-dependent increase of single-strand breaks (SSBs) in DNA from gills of this organism. Verapamil caused no or little increase of SSBs induced by exposure to 0.01 or 0.10 microM AAF, respectively, as measured by the alkaline elution technique. In contrast, in the presence of STP a highly significant and dose-dependent enhancement of AAF-mediated SSBs was measured already at exposure to 0.01 microM AAF. These data indicate (i) that the clam C. fluminea is provided with a P-glycoprotein-like element of the MDR-mechanism, (ii) that this system can be poisoned by chemosensitizers such as verapamil and STP, (iii) the role of protein kinase C in the regulation of MXR function and (iv) the importance of the MXR modulators for the assessment of ecotoxicological effects of pollutants.
74 citations
TL;DR: DB[al]P and B[a]P, both potent animal carcinogens, were the most mutagenic substances in both assays and there was only a corresponding four-fold difference if the nonmutagenic DB[ah]P was excluded.
Abstract: The mutagenicity of benzo[a]pyrene (B[a]P), dibenzo[ae]pyrene (DB[ae]P), dibenzo[ah]pyrene (DB[ah]P), dibenzo[ai]pyrene (DB[ai]P), and dibenzo[al]pyrene (DB[al]P) was measured in quantitative forward mutation assays with bacteria (Salmonella typhimurium TM677) and a metabolically competent cell line derived from human B-lymphoblastoid cells (MCL-5) that contained activity for five cytochrome P450s and microsomal epoxide hydrolase found in human liver. DB[al]P and B[a]P, both potent animal carcinogens, were the most mutagenic substances in both assays. DB[al]P was nearly 50-fold more potent than B[a]P in human cells, but only 60% more mutagenic in Salmonella. The carcinogenic isomer DB[ah]P, though nonmutagenic in bacteria, was active in human cells. The following mutagenic potency series, expressed as the minimum detectable mutagen concentration (MDMC) in nmol/ml, was obtained with Salmonella in the presence of rat liver postmitochondrial supernatant (PMS): DB[al]P (3.7), B[a]P (5.8), DB[ae]P (6.9), DB[ai]P (14.9), DB[ah]P (> 100). None of the compounds were mutagenic in the absence of PMS. In human MCL-5 cells the potency series was: DB[al]P (3.1 x 10(-4)), B[a]P (1.5 x 10(-2)), DB[ae]P (2.5 x 10(-2)), DB[ah]P (0.5), DB[ai]P (3.2). The human cell assay thus exhibited over a 10,000-fold range between the most mutagenic and least mutagenic compound, whereas in the bacterial assay there was only a corresponding four-fold difference if the nonmutagenic DB[ah]P was excluded. The results were discussed in terms of their concordance with animal carcinogenicity studies.
71 citations
TL;DR: The alkaline microgel electrophoresis assay demonstrated the ability to detect DNA damage coinciding with the induction of DNA damage detected in in vitro structural chromosomal aberration and mutation assays for genotoxicity.
Abstract: Genotoxic agents can be detected by measuring DNA damage which result in the migration of DNA from single cells in agarose, using an electrophoretic field under alkaline conditions. The alkaline microgel electrophoresis technique was compared with in vitro structural chromosomal aberration (SCA) and mutation assays using V79 Chinese hamster lung cells and in vivo assays such as the bone marrow micronucleus assay in mice and a hepatocyte DNA repair assay in rats. Genotoxicants tested were those routinely used as positive control compounds in the various assays. In vitro assays included liver S9 for metabolic activation of cyclophosphamide (CP) for the SCA assay and benzo[a]pyrene (BP) for the mutation assay. A highly significant increase in DNA migration was induced by these agents under circumstances where a significant increase in DNA damage was detected using other endpoints. The alkaline microgel electrophoresis assay thus demonstrated the ability to detect DNA damage coinciding with the induction of DNA damage detected in these other assays for genotoxicity.
66 citations
TL;DR: The edible parts of 13 fruits and vegetables and of 12 vegetables--asparagus, green beans, broccoli, brussels sprouts, red and white cabbage, carrots, cauliflower, onions, green peppers, spinach, and tomatoes--were squeezed in order to separate juices and residues to find antimutagenic activities, and mutagenicity induced by IQ was strongly reduced by lignin, weakly by alginic acid and pectin A.
Abstract: The edible parts of 13 fruits - apples, apricots, bananas, blackberries, sweet cherries, red currants, white grapes, oranges, peaches, pears, plums, raspberries, and strawberries - and of 12 vegetables - asparagus, green beans, broccoli, brussels sprouts, red and white cabbage, carrots, cauliflower, onions, green peppers, spinach, and tomatoes - were squeezed in order to separate juices and residues. The residues were washed, lyophilized, and extracted sequentially with n-hexane, dichloromethane, acetone, and 2-propanol. Solvent extracted materials were tested in Salmonella typhymurium TA 98 for antimutagenicity against IQ and MeIQx. We found antimutagenic activities in 96% of the n-hexane extracts, 64% of the dichloromethane extracts, 44% of the acetone extracts, and 36% of the 2-propanol extracts. Since no or only minor differences were seen between the mutagens IQ and MeIQx investigations were continued with IQ only. Additional antimutagenic activities were detected in a total of 29.6% of extracts tested when an enzyme preparation with glycosidase-activities (fecalase) was included in the assay. These activities were found in originally inactive or less active dichloromethane, acetone, and 2-propanol extracts, and are therefore strongly suggestive for the liberation of antimutagenic aglycones from inactive glycosides. The existence of possibly a multitude of antimutagenic factors in fruits and vegetables was1further substantiated by: (1) solvent partitioning of the n-hexane extracts of cauliflower, peaches, and spinach; (2) separation of the n-hexane and dichloromethane extracts of cauliflower, peaches, and spinach into acidid, neutral, and basic compounds; (3) chromatographic analysis of the n-hexane and dichloromethane extracts of spinach. Taken together, antimutagenic activities were present in 32 of 36 subfractions, corresponding to 88.9% In the green vegetables beans, broccoli, and spinach the known antimutagen chlorophyll was proven to contribute considerably to antimutagenic potency. Other important contributions may be caused by various fibers: (I) antimutagenicity of fruit and vegetable solvent extracts was extensively heat stable; (II) heating surprisingly caused an increase of antimutagenic potencies or generated new antimutagenic activities in several solvent fractions, especially of broccoli, white and red cabbage. Indeed, mutagenicity induced by IQ was strongly reduced by lignin, weakly by alginic acid and pectin A, while cellulose, gum arabic, gum guar, and xylan were ineffective. With respect to the mechanisms of antimutagenicity binding of IQ by various fibers and inhibition of cytochrome P-450-dependent monoxygenases might be of major importance since no solvent fraction of any fruit or vegetable was able to reduce mutagenic activity induced by N-OH-IQ in S. typhimurium TA 98NR.
TL;DR: No significant correlation between the level of DNA strand breaks and the weekly contact frequency, the life-time exposure to antineoplastic agents, or the time elapsed since the last handling of the drugs was found in this study.
Abstract: In 91 nurses from several divisions of four hospitals in Germany the genotoxic effect caused by the occupational exposure presumably due to mixing of antineeplastic agents was investigated. The amount of DNA single strand breaks and alkali labile sites in the peripheral mononuclear blood cells of the nurses was measured using the alkaline elution method. In ten nurses handling antineoplastic agents not using recommnded safety precautions such as safety hoods, gloves or surgical masks a 50% higher level of DNA strand breaks and alakali-labile sites (p
TL;DR: The genetic toxicity of chlorpyrifos was examined by employing several end points such as gene mutations in bacteria and mammalian cell cultures, cytogenetic abnormalities in mammalian cells both in vitro and in vivo and induction of DNA damage and repair in rat hepatocytes in vitro.
Abstract: The genetic toxicity of chlorpyrifos [O,O,-diethyl-O-(3,5,6-trichloro-2- pyridinyl)phosphorothioate, C.A.S. Number: 2921-88-2)], an organophosphate insecticide, was examined by employing several end points such as gene mutations in bacteria (Ames test) and mammalian cell cultures (CHO/HGPRT assay), cytogenetic abnormalities in mammalian cells both in vitro (rat lymphocyte chromosomal aberration test, RLCAT) and in vivo (mouse bone marrow micronucleus test) and induction of DNA damage and repair in rat hepatocytes in vitro. There was no indication of genotoxic activity for chlorpyrifos in any of these assays. These results are consistent with the reported lack of carcinogenic potential for chlorpyrifos in both mice and rats.
TL;DR: Investigation of DNA adduct formation after exposure to PCBs found inter-species differences probably reflect metabolic differences leading to different ultimate carcinogens, suggesting that pre-treated cells are required to magnify Aroclor 1254 metabolism.
Abstract: Polychlorinated biphenyls (PCBs) are industrial chemicals which have been detected in fish, birds and humans. They are known to exert marked effects on the liver. They induce hepatocellular carcinoma in rats and birds, and are suspected of being carcinogenic to humans. To better understand the genotoxic effects of PCBs, we used 32P-postlabelling to investigate DNA adduct formation, after exposure to PCBs (Aroclor 1254 and 3,3',4,4'-tetrachlorobiphenyl), in primary cultures of fetal hepatocytes from two animal species and in a human cell line (Hep G2). We also studied the induction of 7-ethoxyresorufin-O-deethylase (EROD) in these PCB-treated cells. The three cell types used are known to express different cytochrome P450 families. The aim was to see whether a correlation could be established between EROD activity (a CYP1A1-related activity) and DNA adduct formation. DNA adducts were found in all three models after exposure to 50 microM 3,3',4,4'-tetrachlorobiphenyl. The number of adducts was higher in quail hepatocytes (37 adducts per 10(9) nucleotides) than in rat hepatocytes or Hep G2 cells (20 adducts per 10(9) nucleotides in both cases). The major adduct was the same in all three cell types, but some adducts were found in only one or two species. These inter-species differences probably reflect metabolic differences leading to different ultimate carcinogens. Exposure to Aroclor 1254 failed to produce significant levels of DNA adducts, suggesting that pre-treated cells are required to magnify Aroclor 1254 metabolism. No correlation was found between adduct formation and the level of EROD induction.
TL;DR: Results showed a significant increase in single-strand DNA breaks in brain cells that peaked at approx.
Abstract: Male Sprague-Dawley rats were intubated with 4 g/kg body weight of ethanol (in a 20%, v/v, water solution). Brain cells were analyzed for single-strand DNA breaks at various post-ethanol administration time points using an alkaline microgel electrophoresis assay. Results showed a significant increase in single-strand DNA breaks in brain cells that peaked at approx. 4 h and returned to control level within 6 h after ethanol administration.
TL;DR: Two structure-activity relationships were noted: (1) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitRiles and (2) the clastogenic activity of the chlorination acetonItriles increased with the number of chlorine substituENTS.
Abstract: Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of six halogenated acetonitriles identified in chlorinated waters (monochloro-, dichloro-, trichloro-, monobromo-, dibromo- and bromochloroacetonitrile). With the SOS chromotest, three of the chemicals studied (dichloro-, dibromo- and bromochloroacetonitrile) were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, all the compounds except dibromoacetonitrile showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for all the six haloacetonitriles studied. Moreover, two structure-activity relationships were noted: (1) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitriles and (2) the clastogenic activity of the chlorinated acetonitriles increased with the number of chlorine substituents.
TL;DR: Results demonstrate that the K1R4F is a representative model for the U.S. cigarette market in comparative Salmonella mutagenicity studies using mainstream smoke condensates.
Abstract: The Salmonella mutagenicity assay has been used to investigate the mutagenicity of cigarette smoke and cigarette smoke condensate. The Kentucky reference (K1R4F) cigarette is designed to be representative of full-flavor, low-tar cigarettes sold in the U.S. and to serve as a reference standard for comparative studies on the chemistry and biological activities of cigarette smoke and condensate. The objective of this study was to determine if the mutagenicity of mainstream smoke condensate from the K1R4F, as measured by the Salmonella mutagenicity assay, is representative of the mutagenic activity of U.S. cigarettes. Mainstream smoke condensates prepared in dimethyl sulfoxide from the K1R4F and 73 brand styles (representing greater than 70% of the total U.S. cigarette market) were assayed using Salmonella typhimurium TA98 and TA100 (+S9) at concentrations of 0, 25, 50, 75, 100, 125 and 250 μg/plate. Revertants/mg condensate were determined by calculating the slopes of the dose-response curves using linear and nonlinear regression models. Revertants/cigarette were determined by multiplying the revertants/mg condensate by the mg condensate/cigarette. No significant differences ( p > 0.05) were observed between the mean mutagenicity of U.S. market and K1R4F mainstream smoke condensates in terms of revertants/mg condensate or revertants/cigarette. Increased variability in mutagenicity was observed among the U.S. brands versus that of the K1R4F. This is not surprising since variability among the U.S. brands would be expected to have both measurement error and brand style variability while the K1R4F variability contains only the measurement error portion. These results demonstrate that the K1R4F is a representative model for the U.S. cigarette market in comparative Salmonella mutagenicity studies using mainstream smoke condensates.
TL;DR: Inhibitory effects of eugenol, a compound present in many spices such as cloves, cardamom etc. and the extracts of Anacyclus pyrethrum and Spilanthes calva, on tobacco-induced mutagenesis were evaluated using Ames Salmonella/microsome assay.
Abstract: Inhibitory effects of eugenol, a compound present in many spices such as cloves, cardamom etc. and the extracts of Anacyclus pyrethrum and Spilanthes calva which are traditionally used in India during the preparation of chewable tobacco, on tobacco-induced mutagenesis were evaluated using Ames Salmonella/microsome assay. Eugenol significantly inhibited (P < 0.001) tobacco-induced mutagenicity at concentrations of 0.5 and 1 mg/plate. Anacyclus pyrethrum extract (1 mg/plate) produced 74.33% inhibition while the extract of Spilanthes calva at 2 mg/plate inhibited tobacco-induced mutagenesis by 86.4%. Eugenol and the plant extracts also inhibited the nitrosation of methylurea in a dose-dependent manner.
TL;DR: It is demonstrated that pre-treatment with garlic extract can lead to significant dose-related reductions in the frequencies of gamma-radiation-induced micronucleated polychromatic erythrocytes and the anticlastogenic effect of garlic extract was observed against lower radiation doses.
Abstract: Garlic extract was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against gamma-radiation-induced chromosomal damage. Together with this, biochemical assays were carried out to determine the changes in sulfhydryl content and glutathione S-transferase activities. Three doses of freshly prepared garlic extract (125, 250 and 500 mg/kg b.w.) were orally administered for 5 consecutive days, and the animals were irradiated 2 h after the final feeding. The results of the micronucleus test demonstrated that pre-treatment with garlic extract can lead to significant dose-related reductions in the frequencies of gamma-radiation-induced (2 Gy) micronucleated polychromatic erythrocytes. The anticlastogenic effect of garlic extract was observed against lower radiation doses of 0.5 and 1 Gy, but not 0.25 Gy. Significant increases in the sulfhydryl content and glutathione S-transferase activity were observed after either pre-treatment with garlic extract or irradiation. However, the irradiated garlic-extract pre-treated animals showed a significant reduction in sulfhydryl content and glutathione S-transferase activities.
TL;DR: The number of CAs/cell and percent aberrant cells increased with an increase in the concentration and period of treatment and the effect was maximum when the cells were analysed 12 h after treatment, as compared to 6 and 24 h.
Abstract: Clastogenic properties of two lanthanide elements praseodymium (Pr) and neodymium (Nd) were evaluated by employing mouse in vivo chromosomal aberrations (CAs) assay. Praseodymium oxide (Pr6O11) and neodymium oxide (Nd2O3) administered intraperitoneally to Swiss albino mice in vivo induced significant increase in the frequency of CAs in bone marrow cells, when compared to negative control. The number of CAs/cell and percent aberrant cells increased with an increase in the concentration and period of treatment. The effect was maximum when the cells were analysed 12 h after treatment, as compared to 6 and 24 h. This is the first report on the clastogenicity of these elements in mouse in vivo.
TL;DR: It is demonstrated that the genotoxic activity of these PAHs and their nitro derivatives can be detected with the somatic cells of the wing imaginal discs of larvae with high bioactivation capacity.
Abstract: The genotoxicity of three polycyclic aromatic hydrocarbons (PAHs) and of three of their nitro derivatives was evaluated in the wing Somatic Mutation And Recombination Test (SMART) in Drosophila melanogaster. Two crosses were used, i.e. the standard cross (ST) and the improved high bioactivation cross (HB) which is characterised by an increased sensitivity to the genotoxic effects of promutagens and procarcinogens. Larvae trans-heterozygous for the two recessive wing cell markers multiple wing hairs (mwh) and flare (flr3) were fed with the test compounds for 48 h. The wings of the surviving flies were analysed for the occurrence of single and twin spots. Naphthalene, 1-nitronaphthalene and 1,5-dinitronaphthalene proved to be more genotoxic in the HB cross than in the ST cross. Anthracene showed a clear genotoxic activity only in the HB cross whereas it was negative in the ST cross. 9-Nitroanthracene gave inconsistent results in both crosses. Phenanthrene was negative in the ST cross, but weakly positive in the HB cross. These results demonstrate that the genotoxic activity of these PAHs and their nitro derivatives can be detected with the somatic cells of the wing imaginal discs of larvae with high bioactivation capacity.
TL;DR: The positive results obtained by nCA analysis support the finding of a significant presence of types of micronuclei that are probably aneuploidy-related in bone marrow of mice following intragastric treatment.
Abstract: Three vanadium salts, vanadyl sulfate (SVO5), sodium orthovanadate (Na3VO4) and ammonium metavanadate (NH4VO3), were tested for induction of genotoxic effects in bone marrow of mice following intragastric treatment. Micronucleus (MN) induction in polychromatic erythrocytes (PCEs), structural (sCA) and numerical (nCA) chromosome aberrations in bone marrow cells were evaluated.
The micronucleus test, performed at different harvesting times (0–72 h), was found to be positive for all compounds tested. In contrast, except for vanadyl sulfate, no difference was found between controls and treated animals in the sCA test performed 24 and 36 h after treatment. At the same sampling intervals, second metaphases (M II) were positively scored for nCA induction for all three vanadium salts. In addition, the frequency of hypoploid and hyperploid cells was shown to be statistically different from the control value. Polyploid cells were also induced by all compounds, but their frequency was not statistically significant. The positive results obtained by nCA analysis support the finding of a significant presence of types of micronuclei that are probably aneuploidy-related. This finding was further supported by the successful classification of such micronuclei on the basis of shape and size according to Tinwell and Ashby (1991) during microscope analysis.
TL;DR: Chromosome aberration test was applied for an organophosphorus insecticide, dichlorvos, using fish as model and proved its efficacy in the fish model without the administration of the chemical by injection.
Abstract: Chromosome aberration test was applied for an organophosphorus insecticide, dichlorvos, using fish as model. Channa punctatus, an ophiocephalid, having a small number (2n = 32) and a rather large size of chromosomes, was used for the purpose. Dichlorvos, with O,O-dimethyl-2,2-dichlorovinyl phosphate as the active component, was dissolved in the aquarium water at concentration level equal to that found in drainage from agricultural fields (0.01 ppm). The chromosomal preparations were made from the kidney cells of the fish after 24, 48, 72 and 96 h intervals. Controls were kept in ordinary water. The aberrations observed were chromatid gaps, sub-chromatid gaps, centromeric gaps, precocious separation of chromatids and polyploidy. These were found to be significantly higher as compared to that of the controls. This test proved its efficacy in the fish model without the administration of the chemical by injection.
TL;DR: The present data indicate that par acetamol interferes with nucleotide excision repair in several mammalian cell types and constitutes a mechanism by which paracetamol may contribute to genotoxicity in humans.
Abstract: Paracetamol blocks DNA replication by inhibiting deoxyribonucleotide (dNTP) synthesis and may therefore also interfere with DNA repair. In the present work various mammalian cell types were treated with genotoxic agents and allowed to repair in the presence or absence of paracetamol. Alkaline elution was used to assay DNA single-strand breaks plus alkali-labile sites (= SSBs). Resting human mononuclear blood cells (MNC) exposed to 4-nitroquinoline N-oxide (NQO, 3 μM) plus 0.3 mM paracetamol contained twice as many DNA SSBs compared to MNC exposed to NQO alone, and the level of SSBs decreased more slowly during repair in the presence of paracetamol. Deoxyribonucleosides reversed the effects of paracetamol. SSBs induced by MMS or X-rays (2.6 Gy) were not increased by paracetamol. Resting and growth-stimulated MNC, HL-60 cells, rat hepatocytes and human fibroblasts exposed to UV-C (3–13 J/m2) showed varying levels of transient SSBs formed during repair but these were consistently higher in the presence of paracetamol (0.3–1 mM). In rat testicular cells SSBs were induced by NQO and the levels were further increased in the presence of paracetamol, whereas after UV almost no SSBs were detected during repair. The cell-type specific levels of transient SSBs after UV did not correlate with the rate of incision of DNA lesions, measured as the rate of SSB accumulation in the presence of repair inhibitors Ara C plus hydroxyurea. Transient SSBs were present in resting MNC for at least 24 h after UV and paracetamol increased these breaks 4-fold however the overall rate of removal of excisable photodamage during repair did not appear to be reduced by the presence of paracetamol. The present data indicate that paracetamol interferes with nucleotide excision repair in several mammalian cell types. This constitutes a mechanism by which paracetamol may contribute to genotoxicity in humans.
TL;DR: The validation of a method for evaluating micronuclei in the bone marrow polychromatic erythrocytes of animals from this test is described to obtain additional information about the genotoxic potential of these compounds without incurring the cost of additional animals or the use of additional test article, which is often in limited supply.
Abstract: A 14-day subchronic toxicity study is routinely conducted in Fischer 344 rats at the Lilly Research Laboratories. This study is done to gather preliminary toxicological information about chemical entities showing efficacy in various pharmacological screens. This manuscript describes the validation of a method for evaluating micronuclei in the bone marrow polychromatic erythrocytes of animals from this test in order to obtain additional information about the genotoxic potential of these compounds without incurring the cost of additional animals or the use of additional test article, which is often in limited supply. Compounds selected for evaluation were acetylsalicylic acid, mitomycin C, cyclophosphamide, colchicine, 6-mercaptopurine, and etoposide. With the exception of colchicine, the results obtained were as expected with acetylsalicylic acid yielding negative results and the other compounds yielding positive results. These findings are consistent with those published for mice (MacGregor et al., Fund. Appl. Toxicol., 14, 513-522, 1990) and show that a bone marrow micronucleus test can be successfully integrated into a routine subchronic rat toxicology study.
TL;DR: The results indicate no discernable relationship between small-for-gestational age (SGA) and related endpoints and the increase in increase of mutations that accompany advanced paternal age.
Abstract: Czeizel recently suggested that intrauterine growth retardation might be of value as a phenotypic endpoint in mutation epidemiology. We hypothesized that if some fraction of small-for-gestational age (SGA) births are due to new germinal mutations, then an association with advanced paternal age should be present. We evaluated the relation between paternal age and SGA, low birthweight, and preterm births using a large sample of births (n = 254,892) from North Carolina. The analyses were restricted to births of mothers aged 20-34 years and adjusted for maternal age, race, education, marital status, gravidity, and smoking. No material increase in the risk of SGA, low birthweight, and preterm delivery was found for fathers in any age category. For example, odds ratios for SGA ranged from 0.87 (fathers aged 50 years or greater) to 1.13 (fathers aged 45-49 years). The results indicate no discernable relationship between SGA and related endpoints and the increase in increase of mutations that accompany advanced paternal age.
TL;DR: Both chlorambucil and melphalan were found to have reproductive effects attributable to cytotoxicity in specific male germ cell stages and to induce dominant lethal mutations and heritable translocations in postmeiotic germ cells, particularly in mid to early stage spermatids.
Abstract: Chemicals used in the treatment of cancer include several that are potent mutagens in a range of in vitro and in vivo assays. For some, genetic effects have also been demonstrated in humans, detected as chromosomal aberrations in peripheral lymphocytes. Because (1) many of these agents are confirmed mutagens, (2) humans are exposed to them in relatively high doses, and (3) an increasing number of early cancer victims are surviving to reproductive age, it is important that information be available on the genetic and reproductive hazards associated with exposure to these agents. Chlorambucil and melphalan are structurally related chemicals that are included in our efforts to identify and assess such hazards among cancer chemotherapy agents. To date, both have been reported to induced specific locus mutations in germ cells of male mice (Russell et al., 1989; Russell et al., 1992b) and melphalan is one of very few chemicals shown to induced such mutations in spermatogonial stem cells. More recently, both chemicals were found to have strong reproductive effects in female mice (Bishop and Generoso, 1995, in preparation). In the present studies, these chemicals were tested for the induction of dominant lethal mutations and heritable translocations in male mice. Both chemicals were found to have reproductive effects attributable to cytotoxicity in specific male germ cell stages and to induce dominant lethal mutations and heritable translocations in postmeiotic germ cells, particularly in mid to early stage spermatids. Thus, relatively extensive data are now available for assessing the genetic and reproductive hazards that may result from therapeutic exposures to these chemicals.
TL;DR: Ethylene glycol ethers, their aldehyde and their acid metabolites were evaluated for their mutagenicity with the Ames test and displayed mutagenic potency in strain TA 97a with and without S9 mix at high concentrations.
Abstract: Ethylene glycol ethers, their aldehyde and their acid metabolites were evaluated for their mutagenicity with the Ames test. The Salmonella typhimurium his- tester strains TA 97a, TA 98, TA 100 and TA 102 were used with and without rat S9 mix. Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol n-butyl ether and their corresponding aldehyde and acid derivatives were tested up to 10(-4) mol/plate (around 10 mg/plate) or up to cytotoxic concentrations. All tested substances gave negative results with TA 98, TA 100 and TA 102 either with or without S9 mix. In contrast, ethylene glycol n-butyl ether (EGBE) and the aldehyde metabolite of ethylene glycol monomethyl ether, methoxyacetaldehyde (MALD), displayed mutagenic potency in strain TA 97a with and without S9 mix at high concentrations. A significant number of revertants was obtained from 19 mumol/plate EGBE (2.2 mg/plate) and from 34 mumol/plate MALD (2.5 mg/plate). At these concentrations the level of revertants reached up to 7-fold and 3-fold the control values for EGBE and MALD respectively.
TL;DR: It is speculated that a complex formation between hemin and benzo[a]pyrene-7,8-diol-9,10-epoxide takes place and that this complexing is the cause of the accelerated degradation.
Abstract: Hemin and chlorophyllin are known to inhibit strongly the mutagenicity of benzo[a]pyrene in the Salmonella assay. To further investigate this phenomenon, a series of these pyrrole pigments including pure samples of Cu- and Fe-chlorins were tested for their potency to inhibit the mutagenicity of benzo[a]pyrene and its metabolites, benzo[a]pyrene-7,8-diol, benzo[a]pyrene4,5-epoxide, and benzo[a]pyrene-7,8-diol-9,10-epoxide. Hemin was the most potent amongthe pigments tested for these inhibitions. Both hemin and Cu-chlorin accelerated efficiently the degradation of benzo[a]pyrene-7,8-diol-9,10-epoxide, and this acceleration seemed to be the predominant mechanism by which these pigments inhibit the overall mutagenicity of benzo[a]pyrene in Salmonella. Based on spectroscopic evidence, we speculate that a complex formation between hemin and benzo[a]pyrene-7,8-diol-9,10-epoxide takes place and that this complexing is the cause of the accelerated degradation.
TL;DR: The toxicity of water samples and extracts was tested with Microtox assay, and acid fractions of the extracts were more toxic than the neutral fractions, which indicates that components responsible for toxic and mutagenic response were at least partly separated between acid and neutral fraction respectively.
Abstract: The present study was conducted on the waters of the Sora river and effluents entering the river. The samples were extracted with XAD-2 resin at different pH and tested for mutagenicity with the modified Ames test using strains S. typhimurium TA98 and TA100. The majority of the mutagenic activity of the samples was found in the neutral pH fraction of the extracts. Strain TA98 in the presence of metabolic activation was the most sensitive condition of mutagenicity. Of the eleven sample extracts, six were positive; neutral fractions of the effluent from wastewater treatment plant, the water leaching from the municipal dump, the water from the lake lying beneath the dump and the untreated effluent, and acid fractions of two samples taken directly from the river. The water leaching from the municipal dump was also mutagenic and toxic without previous extraction. Mutagenic responses before and after extraction of this sample indicate that components responsible for mutagenicity were partly extracted in the neutral fraction. The toxicity of water samples and extracts was tested with Microtox assay, and acid fractions of the extracts were more toxic than the neutral fractions. Comparing the toxicity to the mutagenicity data indicates that components responsible for toxic and mutagenic response were at least partly separated between acid and neutral fraction respectively.