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S. M. Somani - One of the best experts on this subject based on the ideXlab platform.
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Dose response of ethanol ingestion on antioxidant defense system in rat brain Subcellular Fractions.
Neurotoxicology, 1999Co-Authors: K. Husain, E.c Schlorff, R.b. Scott, S. M. SomaniAbstract:This study investigated the response of the antioxidant defense system in brain Subcellular Fractions after oral graded doses of ethanol to rat. Four groups of male Fischer-344 rats were orally administered saline, ethanol 2 g, 4 g, and 6 g/kg, respectively, and sacrificed 1 hour post treatment. Brain cytosol, synaptosomes, microsomes and mitochondria were separated by density gradient differential centrifugation and assayed for antioxidant system. A significant and dose-dependent-decrease in superoxide dismutase (SOD) activity was observed in all brain Subcellular Fractions. Catalase (CAT) activity was significantly decreased in brain mitochondria (67% and 80% of control) at higher doses of ethanol; whereas, CAT activity was significantly increased in cytosol, synaptosomes and microsomes. Glutathione peroxidase (GSH-Px) activity was significantly increased in all brain Subcellular Fractions except in cytosol at higher dose of ethanol. Malondialdehyde (MDA) content was significantly increased in all brain Subcellular Fractions showing dose response of ethanol-induced oxidative stress. The increase in MDA levels in the brain synaptosomes and microsomes were higher at 6 g dose of ethanol (155% and 163% of control) when compared to mitochondria and cytosol. Glutathione (GSH) levels were significantly increased in brain cytosol and microsomes at higher dose of ethanol (164% and 159% of control); whereas, the GSH concentration was significantly decreased in brain synaptosomes and mitochondria. The antioxidant enzyme (AOE) activity ratios (GSH-Px/SOD and GSH-Px + CAT/SOD) were dose dependently increased in all brain Subcellular Fractions, particularly in synaptosomes. The GSH/GSSG ratio was dose dependently increased in brain microsomes. The perturbations in the antioxidant defense system and enhanced lipid peroxidation following graded doses of ethanol ingestion indicate a dose-dependent-oxidative 2133stress response in brain Subcellular compartments of rats.
Judith A. Kelleher - One of the best experts on this subject based on the ideXlab platform.
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Diacylglycerol kinase and lipase activities in rat brain Subcellular Fractions.
Neurochemistry International, 2003Co-Authors: Joanna Strosznajder, Hanna Wikiel, Judith A. KelleherAbstract:Abstract Phosphatidic acid synthesis via diacylglycerol kinase and free fatty acid release via diacylglycerol lipase were investigated in rat brain Subcellular Fractions using membrane-bound [I- 14 C]arachidonoyl-diacylglycerol as substrate. Labeled diacylglycerol was generated by incubating brain membranes containing [I- 14 C]arachidonoyl-phosphatidylinositols in the presence of deoxycholate and Ca 2+ . Incubation of the prelabeled synaptosomes enriched in [1- 14 C]arachidonoyl-diacylglycerols or incubation of brain Subcellular Fractions with heat-treated prelabeled membranes resulted in the release of free fatty acids from the diacylglycerols. When incubations were carried out in the presence of ATP, MgCl 2 and NaF, both free fatty acid release and conversion of diacylglycerols to phosphatidic acids were observed. The conversion of diacylglycerols to phosphatidate or their hydrolysis to free fatty acids were linear with time for at least 15 min. In three brain Subcellular Fractions examined, diacylglycerol kinase activity indicated a pH maximum of 7.4. The free fatty acid release was enhanced slightly by Ca 2+ (1 mM), but Ca 2+ (0.5–4 mM) in the presence of Mg 2+ (10 mM) was inhibitory to the diacylglycerol kinase reaction. Phosphatidate formation was also inhibited by an excessive amount of deoxycholate added to the incubation mixture. Among the brain Subcellular Fractions, diacylglycerol kinase was more active in synaptic vesicles and cytosol than in the microsomal fraction, whereas diacylglycerol lipase activity was higher in the cytosol fraction than in the membrane Fractions. Upon washing the membranes by centrifugation, a substantial portion of the diacylglycerol kinase activity was removed after the first washing, whereas the diacylglycerol lipase activity remained essentially unchanged. The metabolic role of arachidonoyl-diacylglycerols in brain membranes in relation to the biosynthesis of phosphatidate and the release of arachidomic acid is discussed.
Kai Zhong - One of the best experts on this subject based on the ideXlab platform.
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contribution of iron and protein contents from rat brain Subcellular Fractions to mr phase imaging
Magnetic Resonance in Medicine, 2017Co-Authors: Tobias Leutritz, Liane Hilfert, U Busse, K H Smalla, Oliver Speck, Kai ZhongAbstract:PURPOSE Investigation of magnetic susceptibility and chemical exchange as sources of MRI phase contrast between gray and white matter resulting from protein and iron content from Subcellular Fractions. METHODS This study analyzes the iron and macromolecule content of different Subcellular Fractions from rat brain and their relation to the water-resonance frequency by NMR spectroscopy. Additionally, the contributions of susceptibility and exchange were determined with different NMR reference substances. RESULTS Only weak correlations between iron (r = 0.4318, P = 0.76) or protein content (r = 0.4704, P = 0.70) and frequency shift were observed. After membrane depletion, the correlation for iron increased to r = -0.9006 (P = 0.0009), whereas the shift relative to protein content increased much less (r = -0.4982, P = 0.64). Exchange-driven frequency shifts were 1.283 ppb/(mg/ml) for myelin and 0.775 ppb/(mg/ml) for synaptosomes; susceptibility-driven shifts were -1.209 ppb/(mg/ml) for myelin and -0.368 ppb/(mg/ml) for synaptosomes. The ratios between susceptibility and exchange differ significantly from simple protein solutions. CONCLUSIONS As a result of counteracting susceptibility and exchange and increased relative shifts in membrane-depleted Fractions, we conclude that tissue microstructure accounts more for the in vivo phase contrast than in the situation of homogenized tissue. Thus, membranes may generate much of the in vivo MR phase contrast resulting from anisotropy. Magn Reson Med 77:2028-2039, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
K. Husain - One of the best experts on this subject based on the ideXlab platform.
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Dose response of ethanol ingestion on antioxidant defense system in rat brain Subcellular Fractions.
Neurotoxicology, 1999Co-Authors: K. Husain, E.c Schlorff, R.b. Scott, S. M. SomaniAbstract:This study investigated the response of the antioxidant defense system in brain Subcellular Fractions after oral graded doses of ethanol to rat. Four groups of male Fischer-344 rats were orally administered saline, ethanol 2 g, 4 g, and 6 g/kg, respectively, and sacrificed 1 hour post treatment. Brain cytosol, synaptosomes, microsomes and mitochondria were separated by density gradient differential centrifugation and assayed for antioxidant system. A significant and dose-dependent-decrease in superoxide dismutase (SOD) activity was observed in all brain Subcellular Fractions. Catalase (CAT) activity was significantly decreased in brain mitochondria (67% and 80% of control) at higher doses of ethanol; whereas, CAT activity was significantly increased in cytosol, synaptosomes and microsomes. Glutathione peroxidase (GSH-Px) activity was significantly increased in all brain Subcellular Fractions except in cytosol at higher dose of ethanol. Malondialdehyde (MDA) content was significantly increased in all brain Subcellular Fractions showing dose response of ethanol-induced oxidative stress. The increase in MDA levels in the brain synaptosomes and microsomes were higher at 6 g dose of ethanol (155% and 163% of control) when compared to mitochondria and cytosol. Glutathione (GSH) levels were significantly increased in brain cytosol and microsomes at higher dose of ethanol (164% and 159% of control); whereas, the GSH concentration was significantly decreased in brain synaptosomes and mitochondria. The antioxidant enzyme (AOE) activity ratios (GSH-Px/SOD and GSH-Px + CAT/SOD) were dose dependently increased in all brain Subcellular Fractions, particularly in synaptosomes. The GSH/GSSG ratio was dose dependently increased in brain microsomes. The perturbations in the antioxidant defense system and enhanced lipid peroxidation following graded doses of ethanol ingestion indicate a dose-dependent-oxidative 2133stress response in brain Subcellular compartments of rats.
Shixiang Gao - One of the best experts on this subject based on the ideXlab platform.
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Metabolism of polybrominated diphenyl ethers and tetrabromobisphenol A by fish liver Subcellular Fractions in vitro.
Aquatic Toxicology, 2012Co-Authors: Mengnan Shen, Jie Cheng, Shenghu Zhang, Liang Mao, Shixiang GaoAbstract:Abstract Polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA) are two major flame retardants that accumulate in fish tissues and are potentially toxic. Their debrominated and oxidated derivatives were also reported in fish tissues although the sources of theses derivatives were unidentified. Our study was to determine whether PBDEs and TBBPA could be metabolized by fish liver Subcellular Fractions in vitro and to identify what types of metabolites were formed. Liver microsomes and S9 Fractions of crucian carp (Carassius auratus) were exposed to 4,4′-dibromodiphenyl ether (BDE 15), 2,2′,4,4′-tetrabromodiphenyl ether (BDE 47) or TBBPA solutions for 4 h. Exposure of liver Subcellular Fractions to BDE 15 resulted in the formation of bromophenol and two monohydroxylated dibromodiphenyl ether metabolites. Neither in microsomes nor in S9 studies has revealed the presence of hydroxylated metabolites with BDE 47 exposure which indicated that the oxidation reactions in vitro were hindered by the increased number of bromine substituents on the PBDEs. TBBPA underwent an oxidative cleavage near the central carbon of the molecule, which led to the production of 2,6-dibromo-4-isopropyl-phenol and three unidentified metabolites. Another metabolite of TBBPA characterized as a hexa-brominated compound with three aromatic rings was also found in the liver Subcellular Fractions. These results suggest that the biotransformation of BDE 15 and TBBPA in fish liver is mediated by cytochrome P450 (CYP450) enzymes, as revealed by the formation of hydroxylated metabolites and oxidative bond cleavage products. Moreover, further studies on the identification of specific CYP450 isozymes involved in the biotransformation revealed that CYP1A was the major enzyme responsible for the biotransformation of BDE 15 and TBBPA in fish liver Subcellular Fractions and CYP3A4 also played a major role in metabolism of TBBPA.
