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1

A simple procedure for isolation of microsomes from human placenta

100%
Gniot-Szulzycka J., Januszewska B.
Folia Histochemica et Cytobiologica
|
1986
|
tom 24
|
nr 3
2

10-undecynoic acid, an inhibitor of cytochrome P450 4A1, inhibits ethanolamine-specific phospholipid base exchange reaction in rat liver microsomes

75%
Lenart J., Pikula S.
Acta Biochimica Polonica
|
1999
|
tom 46
|
nr 1
1,12-Dodecanedioic acid, the end-product of w-hydroxylation of lauric acid, stimulates in a concentration dependent manner, phosphatidylethanolamine synthesis via ethanolamine-specific phospholipid base exchange reaction in rat liver endoplasmic reticulum. On the other hand, administration to rats of 10-undecynoic acid, a specific inhibitor of w-hydroxylation reaction catalyzed by cytochrome P450 4A1, inhibits the ethanolamine-specific phospholipid base exchange activity by 30%. This is accompanied by a small but significant decrease in phosphatidylethanolamine content in the endoplasmic reticulum and inhibition of cytochrome P450 4A1. On the basis of these results it can be proposed that a functional relationship between cytochrome P450 4A1 and phosphatidylethanolamine synthesis exists in rat liver. Cytochrome P450 4A1 modulates the cellular level of lauric acid, an inhibitor of phospholipid synthesis. In turn, ethanolamine-specific phospholipid base exchange reaction provides molecular species of phospholipids, containing mainly long-chain polyunsaturated fatty acid moieties, required for the optimal activity of cytochrome P450 4A1.
3

Effect of mesitylene on ethanol metabolism in rat liver microsomes

75%
Zajworoniuk H., Rzeczycki W.
Acta Biochimica Polonica
|
1992
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tom 39
|
nr 4
Increased catalase activity was observed in the liver microsomal fraction of ethanol-treated rats (10% v/v aqueous ethanol solution per os for 5 weeks). In contrast, cytochrome P-450 concentration and specific activity of NADPH-cytochrome c reductase remained at the same level as in the liver of control rate (drinking water). The ratio of microsomal H202-generation to catalase activity was lower In the "ethanol" group than in the control one. This phenomenon seems to be related to the increased contribution of the "peroxidatic" reaction (increased rate of ethanot oxidation). Administration of mesitylene (1,3,5-trimethylbenzene) by gastric tube for 3 days (5 mmoles per kg daily) increased cytochrome P-450 concentration» specific activity of NADPH-cytochrome c reductase and ethanol metabolism.
4

Metabolic transformations of antitumor imidazoacridinone, C-1311, with microsomal fractions of rat and human liver

63%
Wisniewska A., Chrapkowska A., Kot-Wasik A., Konopa J., Mazerska Z.
Acta Biochimica Polonica
|
2007
|
tom 54
|
nr 4
831-838
 The imidazoacridinone derivative C-1311 is an antitumor agent in Phase II clinical trials. The molecular mechanism of enzymatic oxidation of this compound in a peroxidase model system was reported earlier. The present studies were performed to elucidate the role of rat and human liver enzymes in metabolic transformations of this drug. C-1311 was incubated with different fractions of liver cells and the reaction mixtures were analyzed by RP-HPLC. We showed that the drug was more sensitive to metabolism with microsomes than with cytosol or S9 fraction of rat liver cells. Incubation of C-1311 with microsomes revealed the presence of four metabolites. Their structures were identified as dealkylation product, M0, as well as a dimer-like molecule, M1. Furthermore, we speculate that the hydroxyl group was most likely substituted in metabolite M3. It is of note that a higher rate of transformation was observed for rat than for human microsomes. However, the differences in metabolite amounts were specific for each metabolite. The reactivity of C-1311 with rat microsomes overexpressing P450 isoenzymes, of CYP3A and CYP4A families was higher than that with CYP1A and CYP2B. Moreover, the M1 metabolite was selectively formed with CYP3A, whereas M3 with CYP4A. In conclusion, this study revealed that C-1311 varied in susceptibility to metabolic transformation in rat and human cells and showed selectivity in the metabolism with P450 isoenzymes. The obtained results could be useful for preparing the schedule of individual directed therapy with C-1311 in future patients.
5

The influence of resveratrol and quercetin on prooxidative effects of metabolic activation of benzo[a]pyrene in vitro

63%
Gawlik M., Gawlik M. B., Brandys J.
Acta Toxicologica
|
2007
|
tom 15
|
nr 2
157-163
6

The induction of cytochrome P450 isoform, CYP4A1, by clofibrate coincides with activation of ethanolamine-specific phospholipid base exchange reaction in rat liver microsomes

63%
Lenart J., Komanska I., Jasinska R., Pikula S.
Acta Biochimica Polonica
|
1998
|
tom 45
|
nr 1
Administration of a hypolipidaemic drug, clofibrate, to rats resulted, 24 h after a single intraperitoneal injection (250 mg/kg body weight), in pronounced enhancement of the rate of phosphatidylethanolamine (PE) synthesis via the PE-specific base exchange (PEBE) reaction in liver microsomes. This was accompanied by 3.4-fold activation of microsomal ω-hydroxylation of lauric acid by cytochrome P450 4A1 isoform (CYP4A1) and an increase in the protein content of this isoform in endoplasmic reticulum (ER) membranes. Since PE represents a class of phospholipids (PL) prerequisite for proper functioning of CYP4A1, and the PEBE reaction is an inducible pathway of PL synthesis in hepatocytes under metabolic stress, one may speculate that this reaction is switched on when extensive remodelling of PL molecular species or/and massive synthesis of lipid bilayer components for membrane assembly is required.
7

Inhibitory and activatory effects of various compounds on cholesterol sulphate sulphohydrolase of human placenta microsomes

51%
Gniot-Szulzycka J., Wieczorek B., Tronowska B.
Bulletin of the Polish Academy of Sciences. Biological Sciences
|
1999
|
tom 47
|
nr 1
8

Dolichyl sulphate and H-phosphonate: Enzymatic reactions with activated sugars

51%
Sizova O. V., Maltsev S. D., Shibaev V. N., Jankowski W. J., Chojnacki T.
Acta Biochimica Polonica
|
1998
|
tom 45
|
nr 4
Two phosphate-modified analogues of dolichyl phosphate were evaluated as substrates or inhibitors of the reactions catalyzed by mammalian microsomal enzymes. Dolichyl H-phosphonate could serve as an efficient acceptor for mannosyl and glucosyl transfer. The reaction products were chromatographically different from those formed from dolichyl phosphate. Lower activity of the H-phosphonate was observed for the reaction of N-acetylglucosaminyl phosphate transfer from UDP-GlcNAc. Dolichyl sulphate was shown not to serve as a substrate for the transfer of mannosyl (from GDP-Man), glucosyl (from UDP-Glc) or N-acetylglucosaminyl phosphate (from UDP-GlcNAc) residues in the presence of rat liver microsomes. Weak inhibitory properties of this analogue were demonstrated.
9
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Effect of diet on lipid peroxidation in liver microsomes, intestine brush border membrane and in blood serum of rats

51%
Tokarz A., Oledzka R., Sulinski A.
Polish Journal of Food and Nutrition Sciences
|
1992
|
tom 01
|
nr 1
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