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  • 1
    ISSN: 1432-1440
    Keywords: Tobacco-specific nitrosamines ; Toxicokinetics ; Genotoxicity ; Systemic effects ; Primary cells ; Detection of DNA damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion. Genotoxicity was determined by alkaline elution, in situ nick translation or microgel electrophoresis. We found that oral application of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces genotoxic effects in the liver (3.125–50 mg/kg), whereas N-nitrosonornicotine (NNN) is only moderately active (50–100 mg/kg). Furthermore, oral administration of NNK, NNN, and of N-nitrosodimethylamine (NDMA), induces DNA damage in the nasal cavity. In peripheral blood lymphocytes genotoxicity of NDMA (〈 2 mg/kg), but not of NNK (50 mg/kg), was observed. NDMA and NNK are just as genotoxic in the liver when administered by inhalation as orally (effective doses: 0.1–1 and 50 mg/kg, respectively). For human cancer, these results indicate that in addition to the susceptibilities in local organs (oral cavity after snuff dipping and lung after tobacco smoke inhalation), these nitrosamines also pose a risk systemically for more remote organs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 111 (1986), S. 108-109 
    ISSN: 1432-1335
    Keywords: N-nitroso-N-acetoxymethyl-N-methylamine ; Syrian golden hamster ; Inhalation ; Tumors of the nasal cavities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Male Syrian golden hamsters inhaled 0.5–1 ppm (=2.7–5.5 mg/m3) of N-nitroso-N-acetoxymethyl-N-methylamine 1 h/week, for 14 weeks. The total dose per animal was calculated as 150–400 μg or 1–3 mg/kg. Four squamous cell carcinomas and one mucoepidermoid carcinoma of the nasal mucosa were observed. No such tumors occurred in the control group.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1335
    Keywords: Benzamidine ; Benzamidoxime ; Mutagenicity ; Salmonella typhimurium ; DNA single-strand breaks ; DNA amplification ; Metabolic conjugates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The genotoxic potentials of benzamidine and benzamidoxime were determined to study the toxicological relevance of the metabolicN-oxygenation (N-hydroxylation) of benzamidines to benzamidoximes. Benzamidoxime induced DNA single-strand breaks (in rat hepatocytes) and DNA amplification in SV40-transformed hamster cells. In the experiments performed, benzamidine itself was only marginally positive in the hepatocyte/DNA single-strand break assay. Since these cells possess an intact metabolization apparatus, the biological activities may be attributed to toxic and genotoxic metabolites formed by biotransformation. In theSalmonella typhimurium mutagenicity test (TA 98 and TA 100) benzamidoxime alone exhibited a low mutagenicity in the TA 98 strain in the presence of rabbit liver S-9 fractions. These results permit recognition of the metabolicN-hydroxylation of benzamidines to benzamidoximes as a process to toxication. Indirect evidence for the formation of a glucuronide of benzamidoxime has been obtained from in vitro experiments, but it could not be established that this process was a decisive factor in the genotoxicity of benzamidoxime.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1335
    Keywords: Nitroalkylamines ; Hepatocytes ; Metabolizing enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary N-nitrodimethylamine is metabolized oxidatively to N-nitrohydroxymethylmethylamine, which decomposes to yield formaldehyde and N-nitromethylamine. All four compounds and N-nitroethylamine were tested for their ability to induce DNA single strand breaks in hepatocytes and in SV 40-transformed Chinese hamster embryo cell lines. Only the two monoalkylnitramines were positive. They induced single strand breaks in hepatocytes, but were not effective in the other cells. Formaldehyde and N-nitrohydroxymethylmethylamine were toxic to the cells. None of the compounds tested was able to induce selective DNA amplification in the two transformed cell lines. Enzymes involved in drug metabolism were assayed in the hamster cell lines. The activity of UDP-glucuronosyltransferase and cytosolic epoxide hydrolase were not detectable. N-nitrodimethylamine demethylation was low. The content of reduced glutathione and the activities of glutathione transferase and membrane bound epoxide hydrolase were comparable to values obtained in the rat liver.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1335
    Keywords: Agaricus bisporus ; Histidine artefacts ; Genotoxic effects ; Salmonella typhimurium ; Primary rat hepatocytes ; DNA amplification ; Short-term in vivo tests ; micronuclei ; DNA single-strand breaks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A. bisporus has been reported to be carcinogenic to mice [Toth et al. (1986) Cancer Res 38:177–180] and mutagenic inSalmonella typhimurium [Sterner et al. (1982) Mutat Res 101:269–281]. The effects of different heat treatments on the mutagenicity of raw, cooked (boiled) and friedA. bisporus extracts in theS. typhimurium test is reported. The spectrum of potential mutagenic activity ofA. bisporus extracts was tested in vitro in Syrian hamster embryo cells for selective DNA amplification and in primary rat hepatocytes for DNA singlestrand breaks. DNA single-strand breaks were also determined in liver cells of rats and micronuclei were measured in bone marrow cells of mice in vivo following oral application ofA. bisporus extracts. It was shown that the complexA. bisporus extracts per se are not detectably mutagenic inS. typhimurium and that the previously observed increase in number of colonies per plate is probably due to a histidine artefact. No indication of genotoxicity was seen in the two in vitro assays with primary mammalian cells with two different end points. No evidence of in vivo genotoxic effects was observed in the rat liver cells. Finally,A. bisporus was not genotoxic in the micronucleus assay of mouse bone marrow cells in contrast to its previously reported carcinogenicity in mice.
    Type of Medium: Electronic Resource
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