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Mechanisms of action of methyl methanesulfonate on Escherichia coli: mutagenesis. DNA damage and repair

100%

Janion C.

Postępy Biochemii

1995

tom 41

nr 5

Helicobacter pylori infection can modulate the susceptibility of gastric mucosa cells to MNNG

70%

Arabski M. , Kazmierczak P. , Wisniewska-Jarosinska M. , Morawiec Z. , Morawiec-Bajda A. , Klupinska G. , Drzewoski J. , Chojnacki J. , Blasiak J.

Cellular and Molecular Biology Letters

2006

tom 11

nr 4

The pathogenesis of stomach cells can be associated with their susceptibility to exogenous dietary irritants, like nitrosamines such as dimethylnitrosamines (DMNA), and to the effects of non-dietary factors, including Helicobacter pylori infection. We used N-methyl-N'-nitro N-nitrosoguanidyne (MNNG) as a surrogate agent that induces a spectrum of DNA damage similar to DMNA. Using the alkaline comet assay, we showed that antioxidants--vitamins C and E, quercetin, and melatonin--reduced the genotoxic effect of MNNG in H. pylori-infected and non-infected human gastric mucosa cells (GMCs). To compare the sensitivity of the stomach and the blood, the experiment was also carried out in peripheral blood. We observed a higher level of DNA damage induced by MNNG in H. pylori-infected than in noninfected GMCs. We did not note any difference in the efficacy of the repair of the damage in either type of GMC. H. pylori infection may play an important role in the pathogenesis of GMCs, as it can modulate their susceptibility to dietary mutagens/carcinogens, thus contributing to gastric cancer.

Wplyw zwiazkow alkilujacych na indukcje zaberrowanych krypt w jelicie grubym szczurow rasy Wistar i myszy rasy Swiss

61%

Czeczot H. , Tudek B.

Bromatologia i Chemia Toksykologiczna

1995

tom 28

nr 1

79-86

Badano wpływ związków alkilujących (DMH, MNU, MNNG, MMS) na indukcję zaberrowanych krypt w jelicie grubym samic szczurów rasy Wistar i myszy rasy Swiss w zależności od dawki, drogi podawania i wieku.

The aim of this work was to study the effect of 4 alkylating agents: 1,2-dimethylhydrazine (DMH), N-nitrosomethylurea (MNU); N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and methyl-methane sulphonate (MMS) on the induction of aberrant crypts (AC) in the colon of female Wistar rats and Swiss mice. It was shown that the standard colon carcinogens (DMH and MNU), when administered intragastrically (per os) to the rats and mice, induced aberrant crypts in the dose-dependent manner. It was also found that 9—10 week rats were more sensitive to abberant crypts induction than the younger 3—4 week animals. The aberrant crypts induced by DMH in the colons of 3—4 week female Wistar rats and 3-week female Swiss mice were more frequent in the middle colon and rectum. MNNG and MMS, administrered in our experiment per os and per rectum only to the 3—4 week-old female rats, also induced AC in the colon. The aberrant crypts were evidently more frequent in the animals receiving MNNG per rectum. Among the studied chemicals, MMS induced relatively few aberrant crypts in the colon of the female rats, and only at higher concentrations. The results of our study confirm the hypothesis that aberrant crypts are biomarkers of colonic preneoplastic lesions and demonstrate that the method is useful as a short-term assay for carinogenicity; it may be also used for studying the carcinogenic process in the colon.