The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Masae Tatematsu - One of the best experts on this subject based on the ideXlab platform.
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Development of carcinoid tumors of the Glandular Stomach and effects of eradication in Helicobacter pylori-infected Mongolian gerbils.
Asian Pacific journal of cancer prevention : APJCP, 2008Co-Authors: Liyu Cao, Tsutomu Mizoshita, Tetsuya Tsukamoto, Yoshiharu Takenaka, Takeshi Toyoda, Xueyuan Cao, Hisayo Ban, Koji Nozaki, Masae TatematsuAbstract:The relation between Helicobacter pylori (Hp) eradication and prevention of Stomach carcinoid development has hitherto remained unclear. We therefore examined this problem using an Hp-infected and Hp-eradicated Mongolian gerbil (MG) model. Enterochromaffin-like (ECL) lesions (hyperplasia/dysplasia and carcinoid) were histopathologically evaluated in the Glandular Stomachs of Hp-infected and Hp-eradicated MGs. In addition, serum gastrin levels were analyzed. Hp infection induced significant increase in the development of ECL lesions in the Glandular Stomach, as well as serum gastrin levels as compared with non-infected MGs, while Hp eradication was associated with significant alleviation. The development of ECL lesions in the Glandular Stomach strongly correlated with titers of anti-Hp antibodies and serum gastrin levels in MGs. In conclusion, Hp infection induces carcinoid development, and Hp eradication prevents its occurrence in the Glandular MG Stomach, this being strongly linked with reduction in serum gastrin levels.
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Development of Carcinoid Tumors of the Glandular Stomach and Effects of Eradication in Helicobacter Pylori-Infected
2007Co-Authors: Liyu Cao, Tsutomu Mizoshita, Tetsuya Tsukamoto, Yoshiharu Takenaka, Takeshi Toyoda, Xueyuan Cao, Hisayo Ban, Koji Nozaki, Masae TatematsuAbstract:The relation between Helicobacter pylori (Hp) eradication and prevention of Stomach carcinoid development has hitherto remained unclear. We therefore examined this problem using an Hp-infected and Hp-eradicated Mongolian gerbil (MG) model. Enterochromaffin-like (ECL) lesions (hyperplasia/dysplasia and carcinoid) were histopathologically evaluated in the Glandular Stomachs of Hp-infected and Hp-eradicated MGs. In addition, serum gastrin levels were analyzed. Hp infection induced significant increase in the development of ECL lesions in the Glandular Stomach, as well as serum gastrin levels as compared with non-infected MGs, while Hp eradication was associated with significant alleviation. The development of ECL lesions in the Glandular Stomach strongly correlated with titers of anti-Hp antibodies and serum gastrin levels in MGs. In conclusion, Hp infection induces carcinoid development, and Hp eradication prevents its occurrence in the Glandular MG Stomach, this being strongly linked with reduction in serum gastrin levels.
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Gastric and intestinal phenotypes and histogenesis of advanced Glandular Stomach cancers in carcinogen-treated, Helicobacter pylori-infected Mongolian gerbils.
Cancer science, 2006Co-Authors: Tsutomu Mizoshita, Tetsuya Tsukamoto, Yoshiharu Takenaka, Xueyuan Cao, Michio Kaminishi, Sosuke Kato, Masae TatematsuAbstract:The Helicobacter pylori-infected Mongolian gerbil (MG) has been established as an appropriate animal model for studies of Stomach cancer development. However, there have hitherto been no data on the phenotypic classification of Glandular Stomach cancers in H. pylori-infected and non-infected MG. We therefore examined the phenotypes of 50 and six advanced Glandular Stomach cancers in H. pylori-infected and non-infected MG, respectively, as well as adjacent non-neoplastic mucosa, using several gastrointestinal epithelial phenotypic markers. The lesions were divided phenotypically into 21 gastric, 24 gastric-and-intestinal mixed, four intestinal and one null types, with 90.0% of the lesions harboring gastric elements and 56.0% demonstrating intestinal phenotypic expression in H. pylori-infected MG. All six lesions were classified as gastric type in non-infected MG. There was no clear correlation with the presence of intestinal metaplasia in surrounding mucosa. In conclusion, our data suggest that most advanced adenocarcinomas retain a gastric cellular phenotype in the Glandular MG Stomach. Thus, it might be proposed that intestinal metaplasia is a paracancerous phenomenon rather than a premalignant condition. H. pylori infection may trigger intestinalization of both Stomach cancers and non-neoplastic mucosa.
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helicobacter pylori infection enhances Glandular Stomach carcinogenesis in mongolian gerbils treated with chemical carcinogens
Carcinogenesis, 1999Co-Authors: Nobuyuki Shimizu, Hayao Nakanishi, Tetsuya Tsukamoto, Ken Ichi Inada, Yuzuru Ikehara, Michio Kaminishi, Shu Kuramoto, Atsushi Sugiyama, Tsutomu Katsuyama, Masae TatematsuAbstract:Helicobacter pylori (Hp) is thought to be a Stomach carcinogen from epidemiological findings. To determine the effects of infection with the bacteria on experimental carcinogenesis, a study of the Glandular Stomach of Mongolian gerbils (MGs) was performed. Male MGs were treated with N-methyl-N'-nitro-N-nitrosoguanidine followed by inoculation with Hp or infected with Hp followed by N-methyl-N'-nitro-N-nitrosoguanidine administration. Animals were killed at week 50, and their excised Stomachs underwent microbiological and histopathological examinations. In addition, a serological investigation was performed. The incidences of adenocarcinomas were significantly higher in animals treated with 60 or 300 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 10 weeks followed by Hp inoculation or Hp followed by 20 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 30 weeks than in the respective controls. Moreover, tumour-bearing animals had higher titres of anti-Hp antibodies than tumour-free animals. Of interest was the finding that a dose of 100 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine given to infected gerbils eradicated the Hp in about half the animals, with a concomitant reduction in the promoting effect. No tumours were found in animals infected with Hp without N-methyl-N'-nitro-N-nitrosoguanidine or non-treated gerbils. Hp infection enhances Glandular Stomach carcinogenesis in MGs treated with N-methyl-N'-nitro-N-nitrosoguanidine. Animals with high titres of anti-Hp antibodies are at greatest risk of developing neoplasms.
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n methyl n nitrosourea concentration dependent rather than total intake dependent induction of adenocarcinomas in the Glandular Stomach of balb c mice
Japanese Journal of Cancer Research, 1998Co-Authors: Takasuke Yamachika, Shoji Fukushima, Hayao Nakanishi, Tetsuya Tsukamoto, Ken Ichi Inada, Nobuyuki Shimizu, Kiyoshi Kobayashi, Masae TatematsuAbstract:The influence of the level of carcinogen exposure on histopathological types and cellular differentiation of the induced tumors was examined in 100 male BALB/c mice given N-methyl-N-nitrosourea (MNU) in their drinking water at 240 ppm on alternate weeks (total exposure: five weeks) (group 1), at 120 ppm similarly (total exposure: ten weeks) (group 2), at 60 ppm for 20 weeks continuously (group 3), or at 30 ppm for 40 weeks continuously (group 4). Forty-three differentiated and 17 undifferentiated type adenocarcinomas were induced. Glandular Stomach carcinomas and undifferentiated type lesions were more common in mice treated with a high concentration of MNU for a short period than with a low concentration of MNU for a long period, even though total measured intake of MNU was smaller (P<0.01). All the induced Glandular Stomach carcinomas, independent of the treatment schedule, consisted entirely of gastric phenotype cells. In conclusion, the induction of Glandular Stomach cancers and the proportion of undifferentiated type lesions depend not on the total quantity, but rather on the concentration of the carcinogen, while the phenotypic expression of tumor cells is not affected by the differences in the administration protocol.
Wakako Ohyama - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of a 28-day repeated-dose micronucleus test in rat Glandular Stomach, colon, and liver using gastrointestinal tract-targeted genotoxic-carcinogens and non-carcinogens.
Mutation research, 2019Co-Authors: Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Shoichi Kado, Wakako OhyamaAbstract:The usefulness of the rat repeated-dose liver and gastrointestinal (GI) tract micronucleus (MN) tests to detect site-specific carcinogens has been shown previously using 22 chemicals in a study conducted by the Mammalian Mutagenicity Study group in the Japanese Environmental Mutagen Society. However, in the 6th International Workshop on Genotoxicity Testing, the need for further data to identify the sensitivity and specificity of the GI tract MN test and the specificity of the liver MN test, for the purpose of regulatory use, was mentioned. In the present study, we conducted additional studies to validate the performance of the 28-day repeated-dose GI tract and liver MN tests using genotoxic Stomach carcinogens, N-nitroso-N-methylurea (MNU) and N-methyl-N-nitrosourethane (NMUT); genotoxic colon carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine hydrochloride (PhIP), and non-carcinogens, sodium chloride, sucrose, and amaranth. Male Crl:CD (SD) rats were administered with each chemical by oral gavage for 28 days and the micronucleated cell frequencies in the Glandular Stomach, colon, and liver were monitored. MNU and NMUT showed positive results in the Glandular Stomach, and PhIP did so in the colon. These carcinogens showed negative results in the liver, which is not a target organ for these chemicals. Negative results were obtained for all three non-carcinogens in the Glandular Stomach, colon, and liver. Therefore, it was shown that the Glandular Stomach and colon MN tests with 28-day repeated-dose regimen have a good sensitivity for detecting genotoxic GI tract carcinogens as positive and have a good specificity to determined non-carcinogens as negative. The negative results with these six chemicals in the liver provide additional evidence supporting the good specificity of the 28-day repeated-dose liver MN test.
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A four-day oral treatment regimen for simultaneous micronucleus analyses in the Glandular Stomach, colon, and bone marrow of rats.
Mutation research, 2013Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Kazunori Narumi, Wakako OhyamaAbstract:Our aim was to develop a multi-tissue micronucleus (MN) test method for the simultaneous analysis of rat Glandular Stomach, colon, and bone marrow. We have evaluated the multi-tissue MN test method with a regimen in which rats were administered chemicals orally once per day for four days and the cells of each tissue were collected 24 h after the final dose. The following compounds were studied: N-nitroso-N-methylurea (MNU), 4-nitroquinoline-1-oxide (4NQO), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), N-methyl-N-nitrosourethane (NMUT), 1,2-dimethylhydrazine 2HCl (DMH), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine HCl (PhIP), KBrO(3), amaranth (AM), and quercetin (QN). The gastrointestinal tract carcinogens increased the frequencies of micronucleated (MNed) cells in target tissue in a dose-dependent manner: MNU in gastric- and colonic-cells; 4NQO, MNNG, and NMUT in gastric cells; DMH and PhIP in colonic cells. In immature erythrocytes, MNU, 4NQO, DMH, and PhIP increased the frequency of MNed cells but MNNG and NMUT did not. The food additive KBrO(3), which is known to be a renal carcinogen, increased the frequencies of MNed cells in the Glandular Stomach and bone marrow. The food additive AM and the plant flavonoid QN, which are non-carcinogenic in most studies, did not cause increased MNed cells in any of the three tissues. Our results indicate that this multi-tissue MN test method is useful for the comprehensive evaluation of the genotoxicity of orally administered compounds.
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In vivo rat Glandular Stomach and colon micronucleus tests: Kinetics of micronucleated cells, apoptosis, and cell proliferation in the target tissues after a single oral administration of Stomach- or colon-carcinogens
Mutation research, 2013Co-Authors: Wakako Ohyama, Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Nobuyoshi YasutakeAbstract:Abstract We have developed in vivo micronucleus (MN) tests by using an epithelial cell suspension isolated from the Glandular Stomach and colon of rodents. In the present study, our aim was to demonstrate the characteristics of the Glandular Stomach and colon MN tests by analyzing time-related changes in MN frequencies, apoptosis and cell proliferation in the target tissues of male CD (SD) rats that were orally administered a single dose of a Stomach- or colon-targeted carcinogen, i.e., N -nitroso- N -methylurea (MNU) or N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) for the Stomach and 1,2-dimethylhydrazine dihydrochloride (DMH) for the colon. After treatment, the MN frequencies significantly increased in the respective target tissues, peaking at 48–96 h and decreasing afterwards. The time-response pattern could be explained by the epithelial cell turnover confirmed with a labeling experiment using the thymidine analog, 5-ethynyl-2′-deoxyuridine (EdU). In the study with MNU and DMH, we also prepared paraffin sections of the respective target tissues for the immunohistochemical evaluation of apoptosis and cell proliferation. The incidence of apoptosis increased in the early phase (6 and/or 24 h) after treatment, and then decreased. Cell proliferation was depressed when a high incidence of apoptosis was observed, and then it recovered until 72 h. MN frequencies increased with the recovery of cell proliferation occurring later than the peak apoptosis response. These results indicated that micronuclei were induced in the Glandular Stomach and colon epithelial cells by administration of the model chemicals. On the other hand, MNU induced significant increases of MNed cells in both the Glandular Stomach and bone marrow in the same rats, while MNNG did only in the Glandular Stomach when administered orally up to 1/4 of the LD 50 . These results suggest that the Glandular Stomach- and colon-MN tests would be useful for evaluating the genotoxicity of agents in the gastrointestinal tract.
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Detection of micronucleated cells and gene expression changes in Glandular Stomach of mice treated with Stomach-targeted carcinogens.
Mutation research, 2008Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Wakako OhyamaAbstract:To assess the genotoxicity of chemicals on the Stomach, we developed in vivo assays that can detect micronucleus induction and gene expression changes in epithelial cells of the Glandular Stomach in mice. Male BALB/c mice were orally given a single dose (100 mg/kg) of N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as Stomach-targeted carcinogens. The Glandular Stomach was excised at 4h, 3 and 4 days after administration, and a single cell suspension of epithelial cells was prepared from the everted Glandular Stomach by EDTA treatment. For determination of micronucleus induction, gastric epithelial cells on days 3 and 4 after administration were fixed with 10% neutral-buffered formalin, stained with a combination of AO-DAPI, and analyzed under fluorescence microscopy. We also examined the induction of micronuclei in peripheral blood of these mice on days 2 and 3 after administration. Moreover, total RNA was extracted from gastric epithelial cells at 4h after administration, and p21 and plk2 expression was analyzed using a quantitative RT-PCR technique. 1) A significant increase of micronucleated cells was observed in the Glandular Stomach in mice treated with N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) compared to mice treated with vehicle. 2) In peripheral blood, induction of micronuclei was observed in mice treated with MNU but not with MNNG. 3) p21 and plk2, which related to cell cycle arrest, were up-regulated in the Glandular Stomach in mice treated with MNU or MNNG compared to mice treated with vehicle. The present study showed that these assays using Glandular Stomach may help to evaluate the genotoxicity of chemicals after oral administration.
Emiko Okada - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of a 28-day repeated-dose micronucleus test in rat Glandular Stomach, colon, and liver using gastrointestinal tract-targeted genotoxic-carcinogens and non-carcinogens.
Mutation research, 2019Co-Authors: Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Shoichi Kado, Wakako OhyamaAbstract:The usefulness of the rat repeated-dose liver and gastrointestinal (GI) tract micronucleus (MN) tests to detect site-specific carcinogens has been shown previously using 22 chemicals in a study conducted by the Mammalian Mutagenicity Study group in the Japanese Environmental Mutagen Society. However, in the 6th International Workshop on Genotoxicity Testing, the need for further data to identify the sensitivity and specificity of the GI tract MN test and the specificity of the liver MN test, for the purpose of regulatory use, was mentioned. In the present study, we conducted additional studies to validate the performance of the 28-day repeated-dose GI tract and liver MN tests using genotoxic Stomach carcinogens, N-nitroso-N-methylurea (MNU) and N-methyl-N-nitrosourethane (NMUT); genotoxic colon carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine hydrochloride (PhIP), and non-carcinogens, sodium chloride, sucrose, and amaranth. Male Crl:CD (SD) rats were administered with each chemical by oral gavage for 28 days and the micronucleated cell frequencies in the Glandular Stomach, colon, and liver were monitored. MNU and NMUT showed positive results in the Glandular Stomach, and PhIP did so in the colon. These carcinogens showed negative results in the liver, which is not a target organ for these chemicals. Negative results were obtained for all three non-carcinogens in the Glandular Stomach, colon, and liver. Therefore, it was shown that the Glandular Stomach and colon MN tests with 28-day repeated-dose regimen have a good sensitivity for detecting genotoxic GI tract carcinogens as positive and have a good specificity to determined non-carcinogens as negative. The negative results with these six chemicals in the liver provide additional evidence supporting the good specificity of the 28-day repeated-dose liver MN test.
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A four-day oral treatment regimen for simultaneous micronucleus analyses in the Glandular Stomach, colon, and bone marrow of rats.
Mutation research, 2013Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Kazunori Narumi, Wakako OhyamaAbstract:Our aim was to develop a multi-tissue micronucleus (MN) test method for the simultaneous analysis of rat Glandular Stomach, colon, and bone marrow. We have evaluated the multi-tissue MN test method with a regimen in which rats were administered chemicals orally once per day for four days and the cells of each tissue were collected 24 h after the final dose. The following compounds were studied: N-nitroso-N-methylurea (MNU), 4-nitroquinoline-1-oxide (4NQO), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), N-methyl-N-nitrosourethane (NMUT), 1,2-dimethylhydrazine 2HCl (DMH), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine HCl (PhIP), KBrO(3), amaranth (AM), and quercetin (QN). The gastrointestinal tract carcinogens increased the frequencies of micronucleated (MNed) cells in target tissue in a dose-dependent manner: MNU in gastric- and colonic-cells; 4NQO, MNNG, and NMUT in gastric cells; DMH and PhIP in colonic cells. In immature erythrocytes, MNU, 4NQO, DMH, and PhIP increased the frequency of MNed cells but MNNG and NMUT did not. The food additive KBrO(3), which is known to be a renal carcinogen, increased the frequencies of MNed cells in the Glandular Stomach and bone marrow. The food additive AM and the plant flavonoid QN, which are non-carcinogenic in most studies, did not cause increased MNed cells in any of the three tissues. Our results indicate that this multi-tissue MN test method is useful for the comprehensive evaluation of the genotoxicity of orally administered compounds.
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In vivo rat Glandular Stomach and colon micronucleus tests: Kinetics of micronucleated cells, apoptosis, and cell proliferation in the target tissues after a single oral administration of Stomach- or colon-carcinogens
Mutation research, 2013Co-Authors: Wakako Ohyama, Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Nobuyoshi YasutakeAbstract:Abstract We have developed in vivo micronucleus (MN) tests by using an epithelial cell suspension isolated from the Glandular Stomach and colon of rodents. In the present study, our aim was to demonstrate the characteristics of the Glandular Stomach and colon MN tests by analyzing time-related changes in MN frequencies, apoptosis and cell proliferation in the target tissues of male CD (SD) rats that were orally administered a single dose of a Stomach- or colon-targeted carcinogen, i.e., N -nitroso- N -methylurea (MNU) or N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) for the Stomach and 1,2-dimethylhydrazine dihydrochloride (DMH) for the colon. After treatment, the MN frequencies significantly increased in the respective target tissues, peaking at 48–96 h and decreasing afterwards. The time-response pattern could be explained by the epithelial cell turnover confirmed with a labeling experiment using the thymidine analog, 5-ethynyl-2′-deoxyuridine (EdU). In the study with MNU and DMH, we also prepared paraffin sections of the respective target tissues for the immunohistochemical evaluation of apoptosis and cell proliferation. The incidence of apoptosis increased in the early phase (6 and/or 24 h) after treatment, and then decreased. Cell proliferation was depressed when a high incidence of apoptosis was observed, and then it recovered until 72 h. MN frequencies increased with the recovery of cell proliferation occurring later than the peak apoptosis response. These results indicated that micronuclei were induced in the Glandular Stomach and colon epithelial cells by administration of the model chemicals. On the other hand, MNU induced significant increases of MNed cells in both the Glandular Stomach and bone marrow in the same rats, while MNNG did only in the Glandular Stomach when administered orally up to 1/4 of the LD 50 . These results suggest that the Glandular Stomach- and colon-MN tests would be useful for evaluating the genotoxicity of agents in the gastrointestinal tract.
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Detection of micronucleated cells and gene expression changes in Glandular Stomach of mice treated with Stomach-targeted carcinogens.
Mutation research, 2008Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Wakako OhyamaAbstract:To assess the genotoxicity of chemicals on the Stomach, we developed in vivo assays that can detect micronucleus induction and gene expression changes in epithelial cells of the Glandular Stomach in mice. Male BALB/c mice were orally given a single dose (100 mg/kg) of N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as Stomach-targeted carcinogens. The Glandular Stomach was excised at 4h, 3 and 4 days after administration, and a single cell suspension of epithelial cells was prepared from the everted Glandular Stomach by EDTA treatment. For determination of micronucleus induction, gastric epithelial cells on days 3 and 4 after administration were fixed with 10% neutral-buffered formalin, stained with a combination of AO-DAPI, and analyzed under fluorescence microscopy. We also examined the induction of micronuclei in peripheral blood of these mice on days 2 and 3 after administration. Moreover, total RNA was extracted from gastric epithelial cells at 4h after administration, and p21 and plk2 expression was analyzed using a quantitative RT-PCR technique. 1) A significant increase of micronucleated cells was observed in the Glandular Stomach in mice treated with N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) compared to mice treated with vehicle. 2) In peripheral blood, induction of micronuclei was observed in mice treated with MNU but not with MNNG. 3) p21 and plk2, which related to cell cycle arrest, were up-regulated in the Glandular Stomach in mice treated with MNU or MNNG compared to mice treated with vehicle. The present study showed that these assays using Glandular Stomach may help to evaluate the genotoxicity of chemicals after oral administration.
Nobuyoshi Yasutake - One of the best experts on this subject based on the ideXlab platform.
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A four-day oral treatment regimen for simultaneous micronucleus analyses in the Glandular Stomach, colon, and bone marrow of rats.
Mutation research, 2013Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Kazunori Narumi, Wakako OhyamaAbstract:Our aim was to develop a multi-tissue micronucleus (MN) test method for the simultaneous analysis of rat Glandular Stomach, colon, and bone marrow. We have evaluated the multi-tissue MN test method with a regimen in which rats were administered chemicals orally once per day for four days and the cells of each tissue were collected 24 h after the final dose. The following compounds were studied: N-nitroso-N-methylurea (MNU), 4-nitroquinoline-1-oxide (4NQO), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), N-methyl-N-nitrosourethane (NMUT), 1,2-dimethylhydrazine 2HCl (DMH), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine HCl (PhIP), KBrO(3), amaranth (AM), and quercetin (QN). The gastrointestinal tract carcinogens increased the frequencies of micronucleated (MNed) cells in target tissue in a dose-dependent manner: MNU in gastric- and colonic-cells; 4NQO, MNNG, and NMUT in gastric cells; DMH and PhIP in colonic cells. In immature erythrocytes, MNU, 4NQO, DMH, and PhIP increased the frequency of MNed cells but MNNG and NMUT did not. The food additive KBrO(3), which is known to be a renal carcinogen, increased the frequencies of MNed cells in the Glandular Stomach and bone marrow. The food additive AM and the plant flavonoid QN, which are non-carcinogenic in most studies, did not cause increased MNed cells in any of the three tissues. Our results indicate that this multi-tissue MN test method is useful for the comprehensive evaluation of the genotoxicity of orally administered compounds.
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In vivo rat Glandular Stomach and colon micronucleus tests: Kinetics of micronucleated cells, apoptosis, and cell proliferation in the target tissues after a single oral administration of Stomach- or colon-carcinogens
Mutation research, 2013Co-Authors: Wakako Ohyama, Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Nobuyoshi YasutakeAbstract:Abstract We have developed in vivo micronucleus (MN) tests by using an epithelial cell suspension isolated from the Glandular Stomach and colon of rodents. In the present study, our aim was to demonstrate the characteristics of the Glandular Stomach and colon MN tests by analyzing time-related changes in MN frequencies, apoptosis and cell proliferation in the target tissues of male CD (SD) rats that were orally administered a single dose of a Stomach- or colon-targeted carcinogen, i.e., N -nitroso- N -methylurea (MNU) or N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) for the Stomach and 1,2-dimethylhydrazine dihydrochloride (DMH) for the colon. After treatment, the MN frequencies significantly increased in the respective target tissues, peaking at 48–96 h and decreasing afterwards. The time-response pattern could be explained by the epithelial cell turnover confirmed with a labeling experiment using the thymidine analog, 5-ethynyl-2′-deoxyuridine (EdU). In the study with MNU and DMH, we also prepared paraffin sections of the respective target tissues for the immunohistochemical evaluation of apoptosis and cell proliferation. The incidence of apoptosis increased in the early phase (6 and/or 24 h) after treatment, and then decreased. Cell proliferation was depressed when a high incidence of apoptosis was observed, and then it recovered until 72 h. MN frequencies increased with the recovery of cell proliferation occurring later than the peak apoptosis response. These results indicated that micronuclei were induced in the Glandular Stomach and colon epithelial cells by administration of the model chemicals. On the other hand, MNU induced significant increases of MNed cells in both the Glandular Stomach and bone marrow in the same rats, while MNNG did only in the Glandular Stomach when administered orally up to 1/4 of the LD 50 . These results suggest that the Glandular Stomach- and colon-MN tests would be useful for evaluating the genotoxicity of agents in the gastrointestinal tract.
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Detection of micronucleated cells and gene expression changes in Glandular Stomach of mice treated with Stomach-targeted carcinogens.
Mutation research, 2008Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Wakako OhyamaAbstract:To assess the genotoxicity of chemicals on the Stomach, we developed in vivo assays that can detect micronucleus induction and gene expression changes in epithelial cells of the Glandular Stomach in mice. Male BALB/c mice were orally given a single dose (100 mg/kg) of N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as Stomach-targeted carcinogens. The Glandular Stomach was excised at 4h, 3 and 4 days after administration, and a single cell suspension of epithelial cells was prepared from the everted Glandular Stomach by EDTA treatment. For determination of micronucleus induction, gastric epithelial cells on days 3 and 4 after administration were fixed with 10% neutral-buffered formalin, stained with a combination of AO-DAPI, and analyzed under fluorescence microscopy. We also examined the induction of micronuclei in peripheral blood of these mice on days 2 and 3 after administration. Moreover, total RNA was extracted from gastric epithelial cells at 4h after administration, and p21 and plk2 expression was analyzed using a quantitative RT-PCR technique. 1) A significant increase of micronucleated cells was observed in the Glandular Stomach in mice treated with N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) compared to mice treated with vehicle. 2) In peripheral blood, induction of micronuclei was observed in mice treated with MNU but not with MNNG. 3) p21 and plk2, which related to cell cycle arrest, were up-regulated in the Glandular Stomach in mice treated with MNU or MNNG compared to mice treated with vehicle. The present study showed that these assays using Glandular Stomach may help to evaluate the genotoxicity of chemicals after oral administration.
Yohei Fujiishi - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of a 28-day repeated-dose micronucleus test in rat Glandular Stomach, colon, and liver using gastrointestinal tract-targeted genotoxic-carcinogens and non-carcinogens.
Mutation research, 2019Co-Authors: Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Shoichi Kado, Wakako OhyamaAbstract:The usefulness of the rat repeated-dose liver and gastrointestinal (GI) tract micronucleus (MN) tests to detect site-specific carcinogens has been shown previously using 22 chemicals in a study conducted by the Mammalian Mutagenicity Study group in the Japanese Environmental Mutagen Society. However, in the 6th International Workshop on Genotoxicity Testing, the need for further data to identify the sensitivity and specificity of the GI tract MN test and the specificity of the liver MN test, for the purpose of regulatory use, was mentioned. In the present study, we conducted additional studies to validate the performance of the 28-day repeated-dose GI tract and liver MN tests using genotoxic Stomach carcinogens, N-nitroso-N-methylurea (MNU) and N-methyl-N-nitrosourethane (NMUT); genotoxic colon carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine hydrochloride (PhIP), and non-carcinogens, sodium chloride, sucrose, and amaranth. Male Crl:CD (SD) rats were administered with each chemical by oral gavage for 28 days and the micronucleated cell frequencies in the Glandular Stomach, colon, and liver were monitored. MNU and NMUT showed positive results in the Glandular Stomach, and PhIP did so in the colon. These carcinogens showed negative results in the liver, which is not a target organ for these chemicals. Negative results were obtained for all three non-carcinogens in the Glandular Stomach, colon, and liver. Therefore, it was shown that the Glandular Stomach and colon MN tests with 28-day repeated-dose regimen have a good sensitivity for detecting genotoxic GI tract carcinogens as positive and have a good specificity to determined non-carcinogens as negative. The negative results with these six chemicals in the liver provide additional evidence supporting the good specificity of the 28-day repeated-dose liver MN test.
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A four-day oral treatment regimen for simultaneous micronucleus analyses in the Glandular Stomach, colon, and bone marrow of rats.
Mutation research, 2013Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Kazunori Narumi, Wakako OhyamaAbstract:Our aim was to develop a multi-tissue micronucleus (MN) test method for the simultaneous analysis of rat Glandular Stomach, colon, and bone marrow. We have evaluated the multi-tissue MN test method with a regimen in which rats were administered chemicals orally once per day for four days and the cells of each tissue were collected 24 h after the final dose. The following compounds were studied: N-nitroso-N-methylurea (MNU), 4-nitroquinoline-1-oxide (4NQO), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), N-methyl-N-nitrosourethane (NMUT), 1,2-dimethylhydrazine 2HCl (DMH), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine HCl (PhIP), KBrO(3), amaranth (AM), and quercetin (QN). The gastrointestinal tract carcinogens increased the frequencies of micronucleated (MNed) cells in target tissue in a dose-dependent manner: MNU in gastric- and colonic-cells; 4NQO, MNNG, and NMUT in gastric cells; DMH and PhIP in colonic cells. In immature erythrocytes, MNU, 4NQO, DMH, and PhIP increased the frequency of MNed cells but MNNG and NMUT did not. The food additive KBrO(3), which is known to be a renal carcinogen, increased the frequencies of MNed cells in the Glandular Stomach and bone marrow. The food additive AM and the plant flavonoid QN, which are non-carcinogenic in most studies, did not cause increased MNed cells in any of the three tissues. Our results indicate that this multi-tissue MN test method is useful for the comprehensive evaluation of the genotoxicity of orally administered compounds.
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In vivo rat Glandular Stomach and colon micronucleus tests: Kinetics of micronucleated cells, apoptosis, and cell proliferation in the target tissues after a single oral administration of Stomach- or colon-carcinogens
Mutation research, 2013Co-Authors: Wakako Ohyama, Emiko Okada, Yohei Fujiishi, Kazunori Narumi, Nobuyoshi YasutakeAbstract:Abstract We have developed in vivo micronucleus (MN) tests by using an epithelial cell suspension isolated from the Glandular Stomach and colon of rodents. In the present study, our aim was to demonstrate the characteristics of the Glandular Stomach and colon MN tests by analyzing time-related changes in MN frequencies, apoptosis and cell proliferation in the target tissues of male CD (SD) rats that were orally administered a single dose of a Stomach- or colon-targeted carcinogen, i.e., N -nitroso- N -methylurea (MNU) or N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) for the Stomach and 1,2-dimethylhydrazine dihydrochloride (DMH) for the colon. After treatment, the MN frequencies significantly increased in the respective target tissues, peaking at 48–96 h and decreasing afterwards. The time-response pattern could be explained by the epithelial cell turnover confirmed with a labeling experiment using the thymidine analog, 5-ethynyl-2′-deoxyuridine (EdU). In the study with MNU and DMH, we also prepared paraffin sections of the respective target tissues for the immunohistochemical evaluation of apoptosis and cell proliferation. The incidence of apoptosis increased in the early phase (6 and/or 24 h) after treatment, and then decreased. Cell proliferation was depressed when a high incidence of apoptosis was observed, and then it recovered until 72 h. MN frequencies increased with the recovery of cell proliferation occurring later than the peak apoptosis response. These results indicated that micronuclei were induced in the Glandular Stomach and colon epithelial cells by administration of the model chemicals. On the other hand, MNU induced significant increases of MNed cells in both the Glandular Stomach and bone marrow in the same rats, while MNNG did only in the Glandular Stomach when administered orally up to 1/4 of the LD 50 . These results suggest that the Glandular Stomach- and colon-MN tests would be useful for evaluating the genotoxicity of agents in the gastrointestinal tract.
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Detection of micronucleated cells and gene expression changes in Glandular Stomach of mice treated with Stomach-targeted carcinogens.
Mutation research, 2008Co-Authors: Emiko Okada, Yohei Fujiishi, Nobuyoshi Yasutake, Wakako OhyamaAbstract:To assess the genotoxicity of chemicals on the Stomach, we developed in vivo assays that can detect micronucleus induction and gene expression changes in epithelial cells of the Glandular Stomach in mice. Male BALB/c mice were orally given a single dose (100 mg/kg) of N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as Stomach-targeted carcinogens. The Glandular Stomach was excised at 4h, 3 and 4 days after administration, and a single cell suspension of epithelial cells was prepared from the everted Glandular Stomach by EDTA treatment. For determination of micronucleus induction, gastric epithelial cells on days 3 and 4 after administration were fixed with 10% neutral-buffered formalin, stained with a combination of AO-DAPI, and analyzed under fluorescence microscopy. We also examined the induction of micronuclei in peripheral blood of these mice on days 2 and 3 after administration. Moreover, total RNA was extracted from gastric epithelial cells at 4h after administration, and p21 and plk2 expression was analyzed using a quantitative RT-PCR technique. 1) A significant increase of micronucleated cells was observed in the Glandular Stomach in mice treated with N-nitroso-N-methylurea (MNU) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) compared to mice treated with vehicle. 2) In peripheral blood, induction of micronuclei was observed in mice treated with MNU but not with MNNG. 3) p21 and plk2, which related to cell cycle arrest, were up-regulated in the Glandular Stomach in mice treated with MNU or MNNG compared to mice treated with vehicle. The present study showed that these assays using Glandular Stomach may help to evaluate the genotoxicity of chemicals after oral administration.