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Sizuyo Sutou - One of the best experts on this subject based on the ideXlab platform.
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achievements by csgmt jems mms the collaborative study group for the Micronucleus Test in the mammalian mutagenesis study group of the environmental mutagen society of japan
Mutation Research\ reviews in Genetic Toxicology, 1996Co-Authors: Sizuyo SutouAbstract:The Collaborative Study Group for the Micronucleus Test (CSGMT) is one of the task groups in the Mammalian Mutagenesis Study Group (MMS) of the Environmental Mutagen Society of Japan (JEMS). It was established in 1982 and has made efforts to understand what the Micronucleus Test is, what are the advantages and disadvantages of the Test as an in vivo detection system for mutagens/carcinogens, and to establish a standard protocol applicable to numerous chemicals. Members of the CSGMT have published more than 75 papers as part of collaborative studies and have contributed to the understanding of the nature of the Micronucleus Test and to setting guidelines for Testing of medicinal and other chemicals. The CSGMT held some workshops to share up-to-date knowledge and techniques on the Micronucleus Test. Through workshops and collaborative studies, the CSGMT contributed to the maintaining of a high standard of knowledge and techniques among Japanese researchers of the Micronucleus Test. This paper reviews achievements made by the CSGMT until now.
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Achievements by CSGMT/JEMS·MMS: the Collaborative Study Group for the Micronucleus Test in the Mammalian Mutagenesis Study Group of the Environmental Mutagen Society of Japan
Mutation research, 1996Co-Authors: Sizuyo SutouAbstract:The Collaborative Study Group for the Micronucleus Test (CSGMT) is one of the task groups in the Mammalian Mutagenesis Study Group (MMS) of the Environmental Mutagen Society of Japan (JEMS). It was established in 1982 and has made efforts to understand what the Micronucleus Test is, what are the advantages and disadvantages of the Test as an in vivo detection system for mutagens/carcinogens, and to establish a standard protocol applicable to numerous chemicals. Members of the CSGMT have published more than 75 papers as part of collaborative studies and have contributed to the understanding of the nature of the Micronucleus Test and to setting guidelines for Testing of medicinal and other chemicals. The CSGMT held some workshops to share up-to-date knowledge and techniques on the Micronucleus Test. Through workshops and collaborative studies, the CSGMT contributed to the maintaining of a high standard of knowledge and techniques among Japanese researchers of the Micronucleus Test. This paper reviews achievements made by the CSGMT until now.
Bernard Ducommun - One of the best experts on this subject based on the ideXlab platform.
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A new in vitro Micronucleus Test in living cells associating biological tracers and high-content imaging
Toxicology Letters, 2016Co-Authors: Vanessa Graillot, Odile Mondesert, Thibault Metenier, Julien Vignard, Valerie Lobjois, Emmanuelle Bazin, Valery Shevchenko, Christiane Guillouzo, Christophe Chesne, Bernard DucommunAbstract:A new in vitro Micronucleus Test in living cells associating biological tracers and high-content imaging
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A new in vitro Micronucleus Test in living cells associating biological tracers and high-content imaging
Toxicology Letters, 2016Co-Authors: Vanessa Graillot, Odile Mondesert, Thibault Metenier, Julien Vignard, Valerie Lobjois, Emmanuelle Bazin, Valery Shevchenko, Christiane Guillouzo, Christophe Chesne, Bernard DucommunAbstract:A new in vitro Micronucleus Test in living cells associating biological tracers and high-content imaging. 47. Annual Meeting of the Environmental Mutagenesis and Genomics Society
Satoru Itoh - One of the best experts on this subject based on the ideXlab platform.
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Recommended protocols for the liver Micronucleus Test: Report of the IWGT working group.
Mutation research. Genetic toxicology and environmental mutagenesis, 2014Co-Authors: Yoshifumi Uno, Satoru Itoh, Takeshi Morita, Mirjam Luijten, Carol Beevers, Shuichi Hamada, Wakako Ohyama, Hironao TakasawaAbstract:At the 6th International Workshop on Genotoxicity Testing (IWGT), the liver Micronucleus Test working group discussed practical aspects of the in vivo rodent liver Micronucleus Test (LMNT). The group members focused on the three methodologies currently used, i.e., a partial hepatectomy (PH) method, a juvenile/young rat (JR) method, and a repeated-dose (RD) method in adult rodents. Since the liver is the main organ that metabolizes chemicals, the LMNT is expected to detect clastogens, especially those that need metabolic activation in the liver, and aneugens. Based on current data the three methods seem to have a high sensitivity and specificity, but more data, especially on non-genotoxic but toxic substances, would be needed to fully evaluate the Test performance. The three methods can be combined with the Micronucleus Test (MNT) using bone marrow (BM) and/or peripheral blood (PB). The ability of the PH method to detect both clastogens and aneugens has already been established, but the methodology is technically challenging. The JR method is relatively straightforward, but animal metabolism might not be fully comparable to adult animals, and data on aneugens are limited. These two methods also have the advantage of a short Testing period. The RD method is also straightforward and can be integrated into repeated-dose (e.g. 2 or 4 weeks) toxicity studies, but again data on aneugens are limited. The working group concluded that the LMNT could be used as a second in vivo Test when a relevant positive result in in vitro mammalian cell genotoxicity Tests is noted (especially under the condition of metabolic activation), and a negative result is observed in the in vivo BM/PB-MNT. The group members discussed LMNT protocols and reached consensus about many aspects of Test procedures. However, data gaps as mentioned above remain, and further data are needed to fully establish the LMNT protocol.
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Gender differences in the liver Micronucleus Test in rats with partial hepatectomy.
Toxicology Letters, 2012Co-Authors: Satoru Itoh, Mayumi Nagata, Chiharu Hattori, Wataru TakasakiAbstract:The liver Micronucleus Test in rats with partial hepatectomy is a useful method to detect pro-clastogens such as diethylnitrosamine, the active metabolites of which do not reach the bone marrow due to their short lifespan. We have already reported that structural or numerical chromosome aberration inducers should be given before or after partial hepatectomy, respectively, to detect genotoxicity in the liver of rats. In the present study, we found that the percentage of binucleated cells in the liver from naive male rats is approximately 60% of that in female rats, which suggests a gender difference in the response to chromosome aberration inducers. Therefore, we investigated the responses to structural chromosome aberration inducers (diethylnitrosamine and 1,2-dimethylhydrazine) and numerical chromosome aberration inducers (colchicine and carbendazim) in male and female rats. The chemicals were given to 8-week-old male and female F344 rats a day before or after partial hepatectomy and hepatocytes were isolated 4 days after the partial hepatectomy. As the results, diethylnitrosamine and 1,2-dimethylhydrazine produced a significant increase in the frequency of micronucleated hepatocytes in both genders and the responses were comparable. In the case of colchicine and carbendazim, higher frequencies in the micronucleated hepatocytes were obtained in males than in females. Taken together, the response to chromosome aberration inducers in male rats was equal to or stronger than that in female rats. It seems that the use of only male rats in the liver Micronucleus Test is sufficient, unless existing data indicate a toxicologically meaningful gender difference in rats.
Toshihiro Ohta - One of the best experts on this subject based on the ideXlab platform.
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Species-specificity of pyrimethamine in the rodent bone marrow Micronucleus Test
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 1997Co-Authors: Tomoko Ono, Tatsuro Sekiya, Yoshiyuki Takahashi, Yu F. Sasaki, Toshihiro OhtaAbstract:An antiprotozoal agent pyrimethamine is a potent clastogen that induces structural chromosome aberrations and micronuclei in cultured Chinese hamster (CHL) cells in vitro. Our previous study on the compound, however, demonstrated no significant induction of micronuclei in the mouse bone marrow Micronucleus Test, even with dosings on 4 consecutive days. In the present study, we investigated the clastogenicity of pyrimethamine in the rat bone marrow Micronucleus Test. An obvious dose-dependent increase in the frequency of micronucleated polychromatic erythrocytes (MNPCEs) was observed when the compound was given 3 times by oral gavage at 20-120 mg/kg/day. The MNPCE frequency at the highest dose was 80 times that of the control group. Single dose of pyrimethamine at 80 and 160 mg/kg also significantly induced MNPCEs. Thus, pyrimethamine showed species-specific effects in rodent bone marrow Micronucleus assays. Our finding implies that Micronucleus Tests using not only mouse, but also rat, may be necessary for the evaluation of clastogens detected in in vitro cytogenetic studies.
Hironao Takasawa - One of the best experts on this subject based on the ideXlab platform.
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Recommended protocols for the liver Micronucleus Test: Report of the IWGT working group.
Mutation research. Genetic toxicology and environmental mutagenesis, 2014Co-Authors: Yoshifumi Uno, Satoru Itoh, Takeshi Morita, Mirjam Luijten, Carol Beevers, Shuichi Hamada, Wakako Ohyama, Hironao TakasawaAbstract:At the 6th International Workshop on Genotoxicity Testing (IWGT), the liver Micronucleus Test working group discussed practical aspects of the in vivo rodent liver Micronucleus Test (LMNT). The group members focused on the three methodologies currently used, i.e., a partial hepatectomy (PH) method, a juvenile/young rat (JR) method, and a repeated-dose (RD) method in adult rodents. Since the liver is the main organ that metabolizes chemicals, the LMNT is expected to detect clastogens, especially those that need metabolic activation in the liver, and aneugens. Based on current data the three methods seem to have a high sensitivity and specificity, but more data, especially on non-genotoxic but toxic substances, would be needed to fully evaluate the Test performance. The three methods can be combined with the Micronucleus Test (MNT) using bone marrow (BM) and/or peripheral blood (PB). The ability of the PH method to detect both clastogens and aneugens has already been established, but the methodology is technically challenging. The JR method is relatively straightforward, but animal metabolism might not be fully comparable to adult animals, and data on aneugens are limited. These two methods also have the advantage of a short Testing period. The RD method is also straightforward and can be integrated into repeated-dose (e.g. 2 or 4 weeks) toxicity studies, but again data on aneugens are limited. The working group concluded that the LMNT could be used as a second in vivo Test when a relevant positive result in in vitro mammalian cell genotoxicity Tests is noted (especially under the condition of metabolic activation), and a negative result is observed in the in vivo BM/PB-MNT. The group members discussed LMNT protocols and reached consensus about many aspects of Test procedures. However, data gaps as mentioned above remain, and further data are needed to fully establish the LMNT protocol.