The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
Abdelkarim Abousalham - One of the best experts on this subject based on the ideXlab platform.
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continuous monitoring of Cholesterol Oleate hydrolysis by hormone sensitive lipase and other Cholesterol esterases
Journal of Lipid Research, 2005Co-Authors: Frederic Carriere, Robert Verger, Stefan Petry, Gunter Muller, Abdelkarim AbousalhamAbstract:Hormone-sensitive lipase (HSL) contributes importantly to the hydrolysis of cholesteryl ester in steroidogenic tissues, releasing the Cholesterol required for adrenal steroidogenesis. HSL has broad substrate specificity, because it hydrolyzes triacylglycerols (TAGs), diacylglycerols, monoacylglycerols, and cholesteryl esters. In this study, we developed a specific Cholesterol esterase assay using Cholesterol Oleate (CO) dispersed in phosphatidylcholine and gum arabic by sonication. To continuously monitor the hydrolysis of CO by HSL, we used the pH-stat technique. For the sake of comparison, the hydrolysis of CO dispersion was also tested using other cholesteryl ester-hydrolyzing enzymes. The specific activities measured on CO were found to be 18, 100, 27, and 3 μmol/min/mg for HSL, Cholesterol esterase from Pseudomonas species, Candida rugosa lipase-3, and Cholesterol esterase from bovine pancreas, respectively. The activity of HSL on CO is ∼4- to 5-fold higher than on long-chain TAGs. In contrast, with all other enzymes tested, the rates of TAG hydrolysis were higher than those of CO hydrolysis. The relatively higher turnover of HSL on CO observed in vitro adds further molecular insight on the physiological importance of HSL in cholesteryl ester catabolism in vivo. Thus, HSL could be considered more as a cholesteryl ester hydrolase than as a TAG lipase.
Raul C. Maranhão - One of the best experts on this subject based on the ideXlab platform.
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Plasma kinetics of chylomicron-like emulsion and lipid transfers to high-density lipoprotein (HDL) in lacto-ovo vegetarian and in omnivorous subjects
European Journal of Nutrition, 2014Co-Authors: Juliana C. Vinagre, Carmen C. G. Vinagre, Fernanda S. Pozzi, Cristiane Z. Zácari, Raul C. MaranhãoAbstract:Purpose Previously, it was showed that vegan diet improves the metabolism of triglyceride-rich lipoproteins by increasing the plasma clearance of atherogenic remnants. The aim of the current study was to investigate this metabolism in lacto-ovo vegetarians whose diet is less strict, allowing the ingestion of eggs and milk. Transfer of lipids to HDL, an important step in HDL metabolism, was tested in vitro. Methods Eighteen lacto-ovo vegetarians and 29 omnivorous subjects, all eutrophic and normolipidemic, were intravenously injected with triglyceride-rich emulsions labeled with ^14C-Cholesterol Oleate and ^3H-triolein. Fractional clearance rates (FCR, in min^−1) were calculated from samples collected during 60 min. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids. Results LDL Cholesterol was lower in vegetarians than in omnivores (2.1 ± 0.8 and 2.7 ± 0.7 mmol/L, respectively, p
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Effects of isotretinoin on the metabolism of triglyceride-rich lipoproteins and on the lipid profile in patients with acne
Archives of Dermatological Research, 2006Co-Authors: Miguel Ângelo Marchi, Raul C. Maranhão, Laura Inês V. Brandizzi, Dorotéia R. S. SouzaAbstract:Isotretinoin treatment alters the plasma lipid levels but the mechanisms and the effects on the metabolism of triglyceride-rich lipoproteins such as chylomicrons and very-low-density lipoproteins remain unclear. We investigated the effect of isotretinoin on the plasma kinetics of emulsion models of triglyceride-rich lipoproteins and the lipid profile. Ten patients with acne were treated with 0.8 mg/kg of isotretinoin over 4 weeks for comparison with non-treated acne patients. In both groups the plasma kinetic study of a triglyceride-rich emulsion double-labeled with ^14C-Cholesterol Oleate and ^3H-triolein was performed after intravenous injection of the emulsion and radioactive counting in plasma samples collected over 60 min. Patients using isotretinoin showed decreased removal from the plasma of the ^3H-triglyceride (median 0.019 min^-1 TG) compared with controls (median 0.044 min^−1, P =0.007), and the removal of the emulsion ^14C-Cholesterol Oleate also tended to be decreased (treatment: 0.011 min^−1; controls: 0.024 min^−1, P =0.06). The values of total and LDL Cholesterol and triglycerides were increased post-treatment ( P
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Accumulation of chylomicron remnants and impaired vascular reactivity occur in subjects with isolated low HDL Cholesterol: Effects of niacin treatment
Atherosclerosis, 2006Co-Authors: Alexandre M. Benjo, Raul C. Maranhão, Silmara R. Coimbra, Ana C Andrade, Desiderio Favarato, Marcos S. Molina, Laura I. BrandizziAbstract:Abstract Fasting hypertriglyceridemia relates with high-density lipoprotein (HDL) Cholesterol, but it is not known whether low HDL Cholesterol is associated with disturbances of chylomicron metabolism. To clarify this issue this metabolism was studied in subjects with low HDL Cholesterol together with vascular reactivity and evaluation of no-flush niacin treatment. Thirty men with HDL 1.04mmol/L were studied. The plasma kinetics of a chylomicron-like emulsion labeled with 14 C-Cholesterol Oleate (CO) and 3 H-triolein (TG) was determined and the fractional clearance rate (FCR, min −1 ) was calculated. Vascular reactivity was evaluated using high-resolution ultrasonography. CO FCR was markedly reduced in the low HDL group compared to controls (3.6×10 −3 ±5.1×10 −3 min −1 versus 12.2×10 −3 ±8.4×10 −3 min −1 , p p p
Frederic Carriere - One of the best experts on this subject based on the ideXlab platform.
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continuous monitoring of Cholesterol Oleate hydrolysis by hormone sensitive lipase and other Cholesterol esterases
Journal of Lipid Research, 2005Co-Authors: Frederic Carriere, Robert Verger, Stefan Petry, Gunter Muller, Abdelkarim AbousalhamAbstract:Hormone-sensitive lipase (HSL) contributes importantly to the hydrolysis of cholesteryl ester in steroidogenic tissues, releasing the Cholesterol required for adrenal steroidogenesis. HSL has broad substrate specificity, because it hydrolyzes triacylglycerols (TAGs), diacylglycerols, monoacylglycerols, and cholesteryl esters. In this study, we developed a specific Cholesterol esterase assay using Cholesterol Oleate (CO) dispersed in phosphatidylcholine and gum arabic by sonication. To continuously monitor the hydrolysis of CO by HSL, we used the pH-stat technique. For the sake of comparison, the hydrolysis of CO dispersion was also tested using other cholesteryl ester-hydrolyzing enzymes. The specific activities measured on CO were found to be 18, 100, 27, and 3 μmol/min/mg for HSL, Cholesterol esterase from Pseudomonas species, Candida rugosa lipase-3, and Cholesterol esterase from bovine pancreas, respectively. The activity of HSL on CO is ∼4- to 5-fold higher than on long-chain TAGs. In contrast, with all other enzymes tested, the rates of TAG hydrolysis were higher than those of CO hydrolysis. The relatively higher turnover of HSL on CO observed in vitro adds further molecular insight on the physiological importance of HSL in cholesteryl ester catabolism in vivo. Thus, HSL could be considered more as a cholesteryl ester hydrolase than as a TAG lipase.
Louis Comeau - One of the best experts on this subject based on the ideXlab platform.
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application of immobilized lipase from candida rugosa to synthesis of Cholesterol Oleate
Journal of Chemical Technology & Biotechnology, 1997Co-Authors: Marie D Jonzo, Abel Hiol, Danielle Druet, Louis ComeauAbstract:Candida rugosa lipase (CRL) has been immobilized on two kinds of ion-exchange resins, Duolite A 568 and Amberlite IRC 50. These preparations were investigated as a tool for the production of Cholesterol Oleate in organic media. An increase in temperature up to 40°C increased the rate of reaction and improved the final ester yield. Under optimal conditions, the reaction yield was followed as a time function, for both lipase preparations with an initial water content of 20%. Then, it was observed that about 78% of the oleic acid was esterified after 10 h using CRL immobilized on Duolite, whereas 73% synthesis of Cholesterol Oleate was reached with CRL immobilized on Amberlite, for the same incubation time. Also, a difference in reaction yield was noticed for the preparations containing sorbitol. In fact, sorbitol treatment might improve the activity of immobilized lipase by preserving the watershell around the catalyst and by increasing the accessibility of the active site to the substrates. In this way, the reaction yield was enhanced, and an increase of 10% synthesis of Cholesterol Oleate was obtained in both cases. © 1997 SCI.
Jarl B Rosenholm - One of the best experts on this subject based on the ideXlab platform.
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lipase catalyzed synthesis and hydrolysis of Cholesterol Oleate in aot isooctane microemulsions
Biocatalysis, 1992Co-Authors: Gun Hedstrom, J P Slotte, M Backlund, Jarl B RosenholmAbstract:We have examined a lipase-catalyzed bidirectional ester synthesis/hydrolysis reaction in a water-in-oil microemulsion system. The reactants were Cholesterol (alcohol), oleic acid (acid) and Cholesterol Oleate (ester), and the solvent system consisted of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water. The reactions were assayed by using [3H]oleic acid, [3H]Cholesterol, or [3H]Cholesterol Oleate for the synthesis and hydrolysis reactions, respectively (separate incubations). The lipase that we used derived from Candida cylindracea, and was used at a concentration of 0.1mg/ml microemulsion. The reactions were performed at 22°C as the reactions proceeded more slowly at higher temperatures. With the initial reactant concentrations set to 10 mM Cholesterol, 1 min oleic acid, and 1 mM Cholesterol Oleate, it was observed that the optimal [H2O]/[AOT] ratio was at about 9 both for the esterification reaction and for the hydrolysis reaction (after 24 h). The hydrolysis reaction was slower than the synt...
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Lipase-Catalyzed Synthesis and Hydrolysis of Cholesterol Oleate in Aot/Isooctane Microemulsions
Biocatalysis, 1992Co-Authors: Gun Hedstrom, J P Slotte, M Backlund, O. Molander And, Jarl B RosenholmAbstract:We have examined a lipase-catalyzed bidirectional ester synthesis/hydrolysis reaction in a water-in-oil microemulsion system. The reactants were Cholesterol (alcohol), oleic acid (acid) and Cholesterol Oleate (ester), and the solvent system consisted of sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water. The reactions were assayed by using [3H]oleic acid, [3H]Cholesterol, or [3H]Cholesterol Oleate for the synthesis and hydrolysis reactions, respectively (separate incubations). The lipase that we used derived from Candida cylindracea, and was used at a concentration of 0.1mg/ml microemulsion. The reactions were performed at 22°C as the reactions proceeded more slowly at higher temperatures. With the initial reactant concentrations set to 10 mM Cholesterol, 1 min oleic acid, and 1 mM Cholesterol Oleate, it was observed that the optimal [H2O]/[AOT] ratio was at about 9 both for the esterification reaction and for the hydrolysis reaction (after 24 h). The hydrolysis reaction was slower than the synt...