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Micronucleus Test (micronucleu + test)
Selected AbstractsFlow cytometry peripheral blood micronucleus test in vivo: Determination of potential thresholds for aneuploidy induced by spindle poisonsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 4 2010Zoryana Cammerer Abstract Non-DNA binding genotoxins (e.g., aneugens), unlike DNA-binding genotoxins, are theoretically expected to show thresholded concentration-effect response curves. This is a major issue in genetic toxicology testing because the identification of thresholds in vivo can provide a safety margin for exposure to a particular compound. In the current study we measured micronucleus induction by flow cytometry to determine the dose-response curves for tubulin interacting agents, a specific class of aneugens. All experiments with aneugens, which include colchicine, vinblastine, vincristine, as well as the clastogen cyclophosphamide (CP) were performed in mice to avoid the splenic elimination of micronucleated reticulocytes, which has been described in rats. Flow cytometry analysis revealed a non-linear dose-dependent increase in micronuclei frequencies for all tested aneugens, and a linear dose response curve for the clastogen, CP. To determine whether micronucleus induction at higher doses was due to chromosome loss (aneuploidy) or chromosome breakage (clastogenicity), flow sorting of the micronucleated reticulocytes and fluorescent in situ hybridization (FISH) with a mouse pan centromeric probe were performed for vinblastine, vincristine, and colchicine. Statistical evaluation of the flow cytometry and FISH data was performed to determine the threshold levels for chromosome loss in vivo. The threshold concentrations for vinblastine, vincristine, and colchicine were found at 0.35, 0.017, and 0.49 mg kg,1, respectively. Environ. Mol. Mutagen., 2010. © 2009 Wiley-Liss, Inc. [source] Protective effect of the cruciferous vegetable mustard leaf (Brassica campestris) against in vivo chromosomal damage and oxidative stress induced by ,-radiation and genotoxic chemicalsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2008Ashu B. Tiku Abstract We evaluated the possible protective effect of the popular Indian cruciferous vegetable mustard leaf (Brassica campestris) against chromosomal damage and oxidative stress induced by ,-radiation, cyclophosphamide (CPH) and urethane (URE), in mice. In vivo bone marrow micronucleus test was performed to assess chromosomal damage, and oxidative stress was monitored by estimating the changes in lipid peroxidation and the status of glutathione (GSH) as well as redox cycle antioxidants. Pretreatment with 50,250 mg/kg body wt of mustard leaf extract (MLE) for seven days significantly reduced the frequencies of micronuclei induced by ,-radiation, CPH and URE. The protective effect against chromosomal damage was associated with modulation of lipid peroxidation as well as an increase in GSH and the GSH-dependent enzyme glutathione S -transferase (GST). Mass spectral analysis showed the presence of glucosinolates in MLE used for the pretreatment of mice. These findings indicate that intake of the green leafy cruciferous vegetable mustard leaf can lead to protection against in vivo genotoxicity and oxidative stress. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source] Feasibility of conducting the micronucleus test in circulating erythrocytes from different mammalian species: An anatomical perspectiveENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 9 2006Ion Udroiu Abstract The in vivo mammalian micronucleus test can be conducted easily on peripheral blood samples since the maturation of erythrocytes involves the loss of the major nucleus. In addition, mature erythrocytes are relatively long-lived, so that the test potentially can detect genotoxic damage caused by chronic exposures. However, some species have spleens that remove micronuclei from the peripheral circulation, making such measurements problematical. This report summarises haematological and mutagenesis studies dealing with this subject and provides an anatomical interpretation of the phenomenon. Anatomical features can be used to identify those species in which micronuclei are removed by the spleen. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source] Detection of clastogenic and aneugenic damage in newborn ratsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2006Ion Udroiu Abstract The last 25 years have seen an ever-growing use of the erythrocyte micronucleus test for measuring damage to mammalian chromosomes in vivo. In addition, staining micronuclei with antikinetochore antibodies from CREST serum discriminates aneugenic from clastogenic damage. The use of the micronucleus test in rats, however, has been problematic because the spleen of adult rats efficiently removes micronucleated erythrocytes from the blood. In the present study, we have treated 5-day-old rats with either X-rays (a clastogen) or vinblastine (an aneugen) and measured micronuclei in erythrocytes from the blood and liver. Each treatment increased the frequency of micronuclei in both tissues, with the percentages of CREST-staining micronuclei reflecting the mechanism of micronucleus induction by the two agents. The results indicate that performing the micronucleus assay in the liver and peripheral blood of 5-day-old rats may be a useful approach for detecting the in vivo genotoxicity of chemical and physical agents. Environ. Mol. Mutagen., 2006. © 2006 Wiley-Liss, Inc. [source] Etoposide and merbarone are clastogenic and aneugenic in the mouse bone marrow micronucleus test complemented by fluorescence in situ hybridization with the mouse minor satellite DNA probeENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2003S.M. Attia Abstract The topoisomerase II (topo II) inhibitors etoposide (VP-16) and merbarone (MER) were investigated with the in vivo micronucleus test (MN test) combined with fluorescence in situ hybridization (FISH) using the mouse minor satellite DNA probe to discriminate MN of clastogenic and aneugenic origin. All experiments were performed with male (102/ElxC3H/El) F1 mice bred in the mouse colony of the GSF Research Center. The sample size per experimental group was five animals and 2,000 polychromatic erythrocytes (PCE) were scored per animal from coded slides in the conventional MN test. A separate set of coded slides was used for the FISH analysis. All treatments consisted of single intraperitoneal injections. Colchicine (COL, 3 mg/kg) and mitomycin (MMC, 1 mg/kg) were used as a positive control aneugen and clastogen, respectively, and these compounds produced the expected responses. A dose of 1 mg/kg VP-16 induced 3.44% MNPCE (compared to the concurrent solvent control of 0.37%, P < 0.001) and of these 39.9% (1.4% MNPCE) showed one or more fluorescent signals. MER (7.5,60 mg/kg) increased the MNPCE frequencies in a dose-dependent manner, with 15 mg/kg being the lowest positive dose. At the highest dose of 60 mg/kg of MER, a total of 4.26% MNPCE were found (compared to 0.31% in the concurrent solvent control, P < 0.001) and of these 46.2% (2.0% MNPCE) contained one or more fluorescent signals. The data demonstrate that VP-16 and MER induced both clastogenic and aneugenic events despite their different modes of topo II inhibition. Environ. Mol. Mutagen. 41:99,103, 2003. © 2003 Wiley-Liss, Inc. [source] Examination of cytotoxicity and mutagenicity of AH26 and AH Plus sealersINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2003I. Mileti Abstract Aim ,To study in vitro the cytotoxic and mutagenic effects of AH26 and AH Plus. Methodology ,Cytotoxic effects on Chinese hamster V79 cells were determined by counting viable cells following incubation with eluations of AH26 and AH Plus. In one set of experiments, the materials were mixed, set for 1 h and then eluted with dimethyl sulphoxide (DMSO) for 1 h, 24 h and 7 days. In the other set, AH26 and AH Plus were mixed and set for 1 h, 24 h and 7 days in physiological saline then crushed and eluted in DMSO for 24 h. The cytotoxic effects of these eluates were evaluated. Three concentrations were chosen to examine the mutagenic effects of AH26 and AH Plus: 5.57, 16.7 and 55.7 ,g mL,1. The structural chromosomal aberration analysis and micronucleus test were performed on human lymphocytes according to standard procedures. Results ,Dose,response curves of cell survival were obtained. Both materials were shown to be cytotoxic in doses larger than 55.7 ,g mL,1, except for AH26, after 7 days setting time. AH Plus was also shown to be toxic in concentrations of 16.7 ,g mL,1, except after 7 days setting time. Neither AH26 nor AH Plus induced a significant increase of chromosomal aberrations or micronuclei induction at any setting time or concentration. Conclusion ,There was no mutagenicity found for AH26 and AH Plus on human lymphocytes in highly controlled conditions in vitro. [source] Bioactivity studies on ,-sitosterol and its glucosidePHYTOTHERAPY RESEARCH, Issue 5 2002Irene M. Villaseñor Abstract ,-Sitosterol and ,-sitosteryl-,- D -glucoside were isolated as analgesic constituents from the leaves of Mentha cordifolia Opiz. The acetic acid-induced writhing test showed that ,-sitosterol and ,-sitosteryl-,- D -glucoside decreased the number of squirms induced by acetic acid by 70.0% and 73.0%, respectively, at a dose of 100,mg /,kg mouse. Statistical analysis using the Kruskall Wallis one-way analysis of variance by ranks showed that these isolates approximate the analgesic activity of mefenamic acid at a 0.001 level of significance. The hot plate method confirmed their analgesic activities, as ,-sitosterol and ,-sitosteryl-,- D -glucoside exhibited a 300% and 157% increase in pain tolerance, respectively, while mefenamic acid, a known analgesic, showed a 171% increase. Neither isolate exhibited antiinflammatory activity using the carrageenan-induced mouse paw oedema assay. ,-Sitosterol also exhibited anthelminthic and antimutagenic activities. In vitro tests using live Ascaris suum as test animals showed that the behaviour of worms treated with ,-sitosterol approximated that of the positive controls, Combantrin and Antiox. An in vivo micronucleus test showed that ,-sitosterol inhibited the mutagenicity of tetracycline by 65.3% at a dose of 0.5,mg /kg mouse. At the same dose, it did not exhibit chromosome-breaking activity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Evaluation of the rodent micronucleus assay by a 28-day treatment protocol: Summary of the 13th Collaborative Study by the Collaborative Study Group for the Micronucleus Test (CSGMT)/Environmental Mutagen Society of Japan (JEMS),Mammalian Mutagenicity Study Group (MMS)ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2001Shuichi Hamada Abstract To examine whether micronucleus tests can be incorporated into general toxicology assays, we performed micronucleus tests applying the treatment protocols typically used in such assays. In this 13th Collaborative Study of the CSGMT, both rats and mice were tested, although rats were used in the majority of the studies. Fifteen mutagens were tested in rats, mainly by oral (p.o.) administration. Micronucleus induction was evaluated 2, 3, and 4 days, and 1, 2, 3, and 28 days after the beginning of the treatment in the peripheral blood, and at 28 days in the bone marrow. Of the 15 chemicals that induced micronuclei in rats in short-term assays, two chemicals (1,2-dimethylhydrazine·2HCl and mitomycin C) were negative in all our experiments, possibly because of insufficient dose levels. The remaining 13 were positive within the estimated dose range of a general toxicology assay, suggesting the possibility of integrating the micronucleus assay into general toxicology assays. Three patterns were observed in micronucleus induction during the period of repeated treatment: (1) gradual increases in micronucleus frequency with sequential doses, (2) a peak at 3,5 days followed by gradual decreases in micronucleus frequency with sequential doses, and (3) a rapid increase in micronucleus frequency followed by a plateau. We evaluated factors that might have been involved in those patterns, such as the spleen function, target organ exposure, extramedullary hematopoiesis, hypothermia, and hypoxia. Another factor we considered was dosage. Because the dosages employed in a general toxicity assay are usually lower than those used in short-term micronucleus assays, this discrepancy was considered the greatest potential problem for integrating the micronucleus assay into general toxicology assays. Our results indicate that the integration of the micronucleus assay into a 28-day toxicological assay is feasible. To serve this purpose, blood samples collected 4 days after the beginning of treatment and blood and bone marrow samples collected at autopsy should be examined. Furthermore, although it is recognized that mice may be suitable for performing independent micronucleus assays, we propose that rats can provide biologically important and relevant information regarding potential chemical mutagens that can be evaluated under conditions used in the conduct of general toxicology studies. Environ. Mol. Mutagen. 37:93,110, 2001 © 2001 Wiley-Liss, Inc. [source] | ||||||||||