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排序方式: 共有506条查询结果,搜索用时 15 毫秒
1.
Cadmium ions introduced at concentration of 30 ppm to the cultivation medium of synchronously growing Chlorella vulgaris decreased concentration of chlorophylls a and b, carotenes alpha and beta and lutein at various stages of the cell cycle, while at concentration of 1 ppm synthesis of the photosynthetic pigments was stimulated. The pigment content in the cadmium treated cells was related to the morphometrically determined changes in the size and shape of the cells. 相似文献
2.
C S Aaron L F Stankowski P R Harbach R Valencia J K Mayo J Mirsalis J H Mazurek K L Steinmetz S K Wiser D M Zimmer 《Mutation research》1989,223(2):111-120
U-48753E is a potential human drug which was subjected to a battery of short-term assays for genetic activity. The compound was negative in the Salmonella (Ames) test, the in vitro UDS assay, the mouse bone-marrow micronucleus test and the Drosophila sex-linked recessive lethal assay. However, it was weakly positive in the CHO/HPRT assay in the presence of metabolic activation (S9). The weak positive response might easily have been labeled artifactual since there was no dose response and the dose level producing positive findings varied from experiment to experiment. In addition, the weak positive response was not confirmed in V79 cells. However, a reproducible dose-related increase in mutants was observed in the AS52/XPRT assay in the presence of S9. Metabolism of this drug proceeds through conversion of aliphatic N-methyl groups to formaldehyde. Addition of formaldehyde dehydrogenase to the S9 resulted in elimination of the mutagenicity of the compound in AS52 cells. Thus, the mutants were probably induced by formaldehyde. From the endogenous levels of formaldehyde in human blood, and the limiting potential therapeutic dose levels, the genotoxic hazard associated with U-48753E is marginal. This assessment of risk and its quantitation depend upon an understanding metabolism and exposure limits imposed by known side effects of the drug. This study can serve as a model for quantitative genetic risk assessment when mutagenicity is due to N-demethylation and formation of formaldehyde in situ. 相似文献
3.
Galanin-Like Immunoreactivity Is Unchanged in Alzheimer''s Disease and Parkinson''s Disease Dementia Cerebral Cortex 总被引:1,自引:1,他引:0
M. Flint Beal Ross A. Clevens Geetinder K. Chattha Usha M. MacGarvey Michael F. Mazurek Steven M. Gabriel 《Journal of neurochemistry》1988,51(6):1935-1941
Galanin is a recently isolated neuropeptide that is of particular interest in dementing disorders because of its known colocalization with choline acetyltransferase in magnocellular neurons of the basal nucleus of Meynert. These neurons degenerate in Alzheimer's disease, and there is a corresponding deficiency of cortical choline acetyltransferase activity. In the present study, galanin-like immunoreactivity was measured in the postmortem cerebral cortex and hippocampus of 10 controls and 14 patients who had had Alzheimer's disease. Significant reductions of choline acetyltransferase activity (50-60%) were found in all regions examined; however, there was no significant effect on concentrations of galanin-like immunoreactivity. Similar measurements were made in postmortem tissues of 12 control and 13 demented Parkinsonian patients who had had Alzheimer-type cortical pathology. Choline acetyltransferase activity was again significantly decreased in all regions examined but there were no significant reductions in galanin-like immunoreactivity. Experimental lesions of the fornix in rats produced parallel significantly correlated reductions of both choline acetyltransferase activity and galanin-like immunoreactivity in the hippocampus. Galanin-like immunoreactivity in the human hypothalamus consisted of two molecular-weight species on gel-permeation chromatography, and two forms were resolved by reverse-phase HPLC. The paradoxical preservation of galanin-like immunoreactivity, despite depletion of the activity of choline acetyltransferase, with which it is colocalized, is as yet unexplained. Recent studies have shown that galanin inhibits both acetylcholine release in the hippocampus and memory acquisition; therefore, preserved galanin may exacerbate the cholinergic and cognitive deficits that accompany dementia. 相似文献
4.
Cypka Mazurek Claude Stiffel Huguette Chalvet Guido Biozzi 《Cancer immunology, immunotherapy : CII》1979,7(2):85-91
Summary The antitumour activity of C. parvum against two different tumours, a lymphosarcoma grafted in XVII mice and a mammary carcinoma grafted in C3H mice, was a radiosensitive phenomenon. A dose of X-rays as low as 100 rads was sufficient to abrogate the C. parvum-induced protection. The duration of this inhibition increased with augmentation of the X-ray dose. The stimulation of macrophage-phagocytic activity induced by C. parvum was not inhibited by a dose of 500 rads. A chronological parallelism has been demonstrated in the recovery of the C. parvum antitumour effect and the restoration of antibody responsiveness after the suppression of these two activities by 500 rads of X-rays in the case of the C3H mice grafted with mammary carcinoma cells. No such concomitant recovery has been observed in XVII mice. In these mice, the recovery of C. parvum antitumour activity took place before the restoration of antibody responsiveness. 相似文献
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Abdullah Mohib Sliwinska Elwira Góralski Grzegorz Latocha Piotr Tuleja Monika Widyna Patrycja Popielarska-Konieczna Marzena 《Plant Cell, Tissue and Organ Culture》2021,147(3):569-582
Plant Cell, Tissue and Organ Culture (PCTOC) - Endosperm, an ephemeral and storage tissue, serves as a source of nutrition and protection during embryo development and germination. It can be used... 相似文献
8.
Anna Juras Edvard Ehler Maciej Chyleński Łukasz Pospieszny Anna Elżbieta Spinek Helena Malmström Maja Krzewińska Krzysztof Szostek Wojciech Pasterkiewicz Marek Florek Stanisław Wilk Barbara Mnich Janusz Kruk Marzena Szmyt Sławomir Kozieł Anders Götherström Mattias Jakobsson Miroslawa Dabert 《American journal of physical anthropology》2021,176(2):223-236
9.
Marzena Wieczorkowska Jacek Zielonka Joanna Celińska Jan Adamus Ewa Ciesielska Andrzej Marcinek 《Free radical research》2013,47(11):1157-1162
It is shown that NADH can be effectively oxidized by 1-methyl-3-nitropyridine in non-enzymatic and enzyme-mediated processes. Mechanistic issues of these reactions are discussed. These processes seem to contribute to the observed cytotoxicity of 1-methyl-3-nitropyridine. A key role of 1-methyl-3-nitropyridinyl radical formed in the enzyme-mediated processes is emphasized. 相似文献
10.
Aleksandra Markiewicz Marzena We?nicka-Ja?kiewicz Jaros?aw Skokowski Janusz Ja?kiewicz Jolanta Szade Jacek Jassem Anna J. ?aczek 《PloS one》2013,8(8)