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Biochemistry Feb 1966
Topics: Animals; Cattle; In Vitro Techniques; Microsomes; Surface-Active Agents; Thymus Gland; Ultracentrifugation
PubMed: 5940958
DOI: 10.1021/bi00866a049 -
Cancer Letters Jan 1981The effects of modulation of microsomal epoxide hydrolase activity on the binding of calf thymus DNA of benzo[alpha]pyrene metabolically activated by rat liver...
The effects of modulation of microsomal epoxide hydrolase activity on the binding of calf thymus DNA of benzo[alpha]pyrene metabolically activated by rat liver microsomes were investigated. In systems where microsomal epoxide hydrolase levels were not manipulated, 2 major bound species, one derived from 9-hydroxybenzo[alpha]pyrene and the other derived from benzo[alpha]pyrene 7,8-dihydrodiol, were found in approximately equivalent amounts. When epoxide hydrolase levels were increased, either by addition in vitro of purified enzyme or by induction in vivo by trans-stilbene oxide, the binding of the benzo[alpha]pyrene 7,8-dihydrodiol product was increased, while the binding of the 9-hydroxybenzo[alpha]pyrene product was practically eliminated. When microsomal epoxide hydrolase activity was decreased by selective inhibition with low concentrations of 1,1,1-trichloropropene 2,3-oxide, the binding of the species derived from 9-hydroxybenzo[alpha]pyrene was increased several-fold, while that of the species derived from benzo[alpha]pyrene 7,8-dihydrodiol was greatly decreased. The results indicate that the binding species derived from 9-hydroxybenzo[alpha]pyrene is formed through a metabolic pathway leading to an epoxide which is a substrate of microsomal epoxide hydrolase and that microsomal epoxide hydrolase is important in regulating the pattern of binding of individual microsomally-formed benzo[alpha]pyrene metabolites to DNA.
Topics: Animals; Benzopyrenes; Biotransformation; DNA; Enzyme Induction; Epoxide Hydrolases; Male; Methylcholanthrene; Microsomes, Liver; Rats
PubMed: 7248922
DOI: 10.1016/0304-3835(81)90105-1 -
Biochemical Medicine and Metabolic... Apr 1991This study indicates for the first time the presence of cytochrome P450 in the microsomes of Euglena grown in lactate medium and substantiates the use of Euglena as a...
This study indicates for the first time the presence of cytochrome P450 in the microsomes of Euglena grown in lactate medium and substantiates the use of Euglena as a hepatic cell model. Similar effects of ethanol on Euglena and on rat hepatic microsomes were demonstrated: (i) decrements in the quantities of FA per milligram of proteins; (ii) increases in the proportions of PE; (iii) decreases in the proportions of PC; and (iv) production of cytochrome P450, degraded in P420. The citrulline-malate reestablishes in the microsomes the phospholipid environment and the cytochrome P450 concentration. These findings illustrate that the complex acts on the lipid peroxidation via the changes in cytochrome P450 activity.
Topics: Animals; Citrulline; Cytochrome P-450 Enzyme System; Ethanol; Euglena gracilis; Fatty Acids; Kinetics; Malates; Microsomes; Phospholipids
PubMed: 1909150
DOI: 10.1016/0885-4505(91)90030-o -
The Journal of Biophysical and... Mar 1956Rat liver, liver homogenates, and microsome fractions separated therefrom were examined systematically in the electron microscope in sections of OsO(4)-fixed,...
Rat liver, liver homogenates, and microsome fractions separated therefrom were examined systematically in the electron microscope in sections of OsO(4)-fixed, methacrylate-embedded tissue and pellets. It was found that most microsomes are morphologically identical with the rough surfaced elements of the endoplasmic reticula of hepatic cells. They appear as isolated, membrane-bound vesicles, tubules, and cisternae which contain an apparently homogeneous material of noticeable density, and bear small, dense particles (100 to 150 A) attached to their outer aspect. In solutions of various osmolar concentrations they behave like osmometers. The findings suggest that they derive from the endoplasmic reticulum by a generalized pinching-off process rather than by mechanical fragmentation. The microsome fractions contain in addition relatively few vesicles free of attached particles, probably derived from the smooth surfaced parts of the endoplasmic reticula. Dense, peribiliary bodies represent a minor component of the same fractions. The microsomes derived from 1 gm. wet weight liver pulp contained (averages of 10 experiments) 3.09 mg. protein N, 3.46 mg. RNA (RNA/protein N = 1.12), and 487 microg. phospholipide P. They displayed DPNH-cytochrome c reductase activity and contained an alcohol-soluble hemochromogen. The microsome preparations proved resistant to washing and "aging." Treatment with versene and incubation with ribonuclease (30 minutes at 37 degrees C.) resulted in appreciable losses of RNA and in partial or total disappearance of attached particles. Treatment with deoxycholate (0.3 to 0.5 per cent, pH = 7.5) induced a partial clarification of the microsome suspensions which, upon centrifugation, yielded a small pellet of conglomerated small, dense particles (100 to 150 A) with only occasionally interspersed vesicles. The pellet contained approximately 80 to 90 per cent of the RNA and approximately 20 per cent of the protein N of the original microsomes. The supernatant accounted satisfactorily for the materials lost during deoxycholate treatment. The findings suggest that the microsomal RNA is associated with the small particles whereas most of the protein and nearly all of the phospholipide, hemochromogen, and DPNH-cytochrome c reductase activity are associated with the membrane or content of the microsomes.
Topics: Animals; Centrifugation; Endoplasmic Reticulum; Liver; Membranes; Microsomes, Liver; Phospholipids; Proteins; RNA; Rats
PubMed: 13319380
DOI: 10.1083/jcb.2.2.171 -
Biochimica Et Biophysica Acta Feb 1975Microsome/cytosol preparations from adipose tissue of the mouse, pig, rat and chicken and from pig liver synthesize triacylglycerols containing a fatty acid distribution...
Microsome/cytosol preparations from adipose tissue of the mouse, pig, rat and chicken and from pig liver synthesize triacylglycerols containing a fatty acid distribution consistent with that in their respective fats. Since the incorporation of fatty acids depends on the presence of glycerol phospahte and no loss of tritium occurs during the incorporation of sn-[2-3 H]glycerol 3-phosphate into triacylglycerols, it would appear that the specific distribution is a property of the transacylases of the glycerophosphate pathway. The apparent Michaelis constant for sn-glycerol 3-phosphate, measured either by sn-glycerol 3-phosphate or palmitate incorporation, averaged 1.4-10-4 M both the mouse and pig adipose tissue enzyme systems.
Topics: Adipose Tissue; Animals; Chickens; Cytosol; Fatty Acids; Liver; Mice; Microsomes; Microsomes, Liver; Organ Specificity; Rats; Species Specificity; Swine; Triglycerides
PubMed: 1120143
DOI: 10.1016/0005-2760(75)90010-7 -
Cancer Research Feb 1978We have used high-pressure liquid chromatography and the Salmonella/microsome mutagenicity test to look for mutagenic impurities in 11 carcinogens and noncarcinogens....
We have used high-pressure liquid chromatography and the Salmonella/microsome mutagenicity test to look for mutagenic impurities in 11 carcinogens and noncarcinogens. Because of the million-fold range in mutagenic potency observed in the Salmonella test, even trace amounts of potent mutagenic impurities in a nonmutagenic compound could be detected. The mutagenicity of 7-hydroxy-2-acetylaminofluorene, a noncarcinogen in the standard animal carcinogenicity tests, is shown to be due to a small amount of impurity, which is probably the potent carcinogen 2-acetylaminofluorene. This is discussed in relation to the statistical limitations of animal carcinogenicity tests. We also discuss the role of mitogenic impurities in assessing the mutagenicity of environmental (and industrial) chemicals with high-sensitivity mutagenicity assays, such as the Salmonella/microsome test.
Topics: Biological Assay; Carcinogens; Chromatography, Liquid; Drug Contamination; Evaluation Studies as Topic; Microsomes; Mutagens; Salmonella typhimurium
PubMed: 340030
DOI: No ID Found -
Hepatology (Baltimore, Md.) 1985
Topics: Autoantibodies; Hepatitis; Humans; Kidney; Liver; Microsomes
PubMed: 4029901
DOI: 10.1002/hep.1840050540 -
FEBS Letters Nov 1991We have determined the effect of prolonged ethanol treatment on several enzyme activities related to lipid metabolism in chick-brain and liver microsomes. Ethanol... (Comparative Study)
Comparative Study
We have determined the effect of prolonged ethanol treatment on several enzyme activities related to lipid metabolism in chick-brain and liver microsomes. Ethanol increased microsome cholesterol levels in both organs. The treatment caused a marked increase in the hepatic HMG-CoA reductase and ACAT activities while in the brain a clear decrease was found in these enzyme activities. At the same time the activity of reacylation of phospholipids, was clearly modified in both brain and liver. Thus, while in the liver the turnover of acyl moieties of phosphatidylethanolamine, sphingomyelin and phosphatidylinositol was enhanced by ethanol consumption, in the brain only the reacylation of phosphatidylserine increased to any significant extent. These results indicate that ethanol exerts a differential action in brain and liver, namely cholesterol synthesis and esterification decreased in brain and increased in chick liver. Ethanol also induces faster phospholipid metabolism in both brain and liver microsomes.
Topics: Animals; Brain; Chickens; Drug Administration Schedule; Ethanol; Hydroxymethylglutaryl CoA Reductases; Lipid Metabolism; Male; Microsomes; Microsomes, Liver; Sterol O-Acyltransferase
PubMed: 1959666
DOI: 10.1016/0014-5793(91)81190-j -
Journal of Chromatography. A Jan 2011
Editorial on "Stereoselective determination of drugs and metabolites in body fluids, tissues and microsomal preparations by capillary electrophoresis (2000-2010)" by Jitka Caslavska and Wolfgang Thormann.
Topics: Body Fluids; Electrophoresis, Capillary; Microsomes; Pharmaceutical Preparations; Stereoisomerism
PubMed: 20933236
DOI: 10.1016/j.chroma.2010.09.039 -
Experimental and Molecular Pathology Oct 1972
Topics: Amidohydrolases; Analysis of Variance; Animals; Cholera; Cholesterol; Disease Models, Animal; Epithelial Cells; Epithelium; Glycolipids; Ileum; Intestinal Mucosa; Microsomes; Neuraminic Acids; Neuraminidase; Phospholipids; Proteins; Rabbits; Sucrase; Toxins, Biological; Trehalase; Vibrio cholerae
PubMed: 5073840
DOI: 10.1016/0014-4800(72)90068-8