bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereospecificity of monoacylglycerol and diacylglycerol acyltransferases from rat intestine as determined by chiral phase high‐performance liquid chromatography
Authors: Lehner Richard , Kuksis Arnis , Itabashi Yataka 
Published: November 2006

AbstractUsing chiral phase high‐performance liquid chromatography of diacylglycerols, we have redetermined the ratios of 1,2‐/2,3‐diacyl‐sn‐glycerols resulting from acylation of 2‐monoacylglycerols by membrane bound and solubilized triacylglycerol systhetase of rat intestinal mucosa. With 2‐oleoyl[‐3H]glycerol as the acyl acceptor and oleoyl‐CoA as the acyl donor, 97–98% of the diacylglycerol product was 1,2(2,3)‐dioleoyl‐sn‐glycerol, 90% of which was thesn‐1,2‐and 10% thesn‐2,3‐enantiomer. The remaining diacylglycerol (less than 3%) was thesn‐1,3‐isomer. The overall yield of acylation products was 70%, of which 60% were diacylglycerols and 40% triacylglycerols. With 2‐oleylglycerol ether as the acyl acceptor and [1‐14C]oleoyl‐CoA as the acyl donor, 90% of the diradylglycerol was 1‐oleoyl‐2‐oleyl‐sn‐glycerol and 10% was the 2‐oleyl‐3‐oleoyl‐sn‐glycerol. The diradylglycerols made up 96% and the triradylglycerols 4% of the radioactive product. With 1‐palmitoyl‐sn‐glycerol as the acyl acceptor and [1‐14C]oleoyl‐CoA as the acyl donor, the predominant reaction product was 1‐palmitoyl‐3‐oleoyl‐sn‐glycerol. The 3‐palmitoyl‐sn‐glycerol was not a suitable acyl acceptor. Both 1,2‐ and 2,3‐diacyl‐sn‐glycerols were substrates for diacylglycerol acyltransferase as neither isomer was favored when 1,2‐dioleoyl‐rac‐[2‐3H]glycerol was used as the acyl acceptor. There was a marked decrease in the acylation of the 1(3)‐oleoyl‐2‐oleyl‐sn‐glycerol to the 1,3‐dioleoyl‐2‐oleyl‐sn‐glycerol. It is concluded that neither monoacylglycerol nor diacylglycerol acyltransferase exhibit absolute stereospecificity for acylglycerols as fatty acid acceptors.
Structural analysis of oxidation products of urofuran acid by hypochlorous acid
Authors: Ohki Toyokazu , Maeda Kenji , Sakakibara Jinsaku , Suzuki Eiji , Yamanaka Naoki 
Published: November 2006

AbstractThe oxidation of urofuran acid derivatives (1–2) by hypochlorous acid (HOCl) was investigated with the goal to possibly simplify the detection of their metabolites in biological materials. The oxidation products of 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furanpropionic acid (1) were obtained as an isomeric mixture and confirmed to exist ascis (3a) andtrans (3b) isomers, based on their13C nuclear magnetic resonance (NMR) spectra. Similarly, the products of 5‐H substituted acid 2 obtained by oxidation with HOCl were identified as 4a and 4b by13C and1H NMR which indicated the presence ofcis andtrans hemiacetal hydrogens at C‐5 in a ratio of 2.11∶1. The oxidation was found to proceed in a manner different from that of the F‐acid, because of the presence of the electron withdrawing COOCH3 group at C‐3 which favored the nucleophilic attack on the carbonyl group to affordcis‐ andtrans‐2,5‐dihydroxy‐2,5‐dihydrofurans (3a−b, 4a−b).
Synthesis of phenyl substituted C18 furanoid fatty esters
Authors: Lie Ken Jie Marcel S. F. , Wong K. P. 
Published: November 2006

AbstractMethyl 9,12‐epoxy‐10‐phenyl‐9,11‐octadecadienoate was prepared by acid catalyzed cyclization of methyl 9,12‐dioxo‐10‐phenyloctadecanoate, which was derived from the oxidation of methyl 9‐hydroxy‐12‐oxo‐10‐phenyloctadecanoate. The latter was exclusively obtained from methylcis‐9,10‐epoxy‐12‐oxooctadecanoate with phenyllithium in the presence of copper (I) bromide. A mixture of positional isomers, methyl 9,12‐epoxy‐10(11)‐phenyl‐9,11‐octadecadienoates, was also prepared by another route. The spectroscopic properties of the various intermediates and products were studied. The positional isomers of the phenyl substituted furanoid fatty esters were characterized by13C nuclear magnetic resonance spectrometry.
The enrichment of n−3 polyunsaturated fatty acids using aminopropyl solid phase extraction columns
Authors: Wilson Robert , James Henderson R. , Burkow Ivan C. , Sargent John R. 
Published: November 2006

AbstractA rapid, simple and reliable method is described for the preparation of concentrates of methyl or ethyl esters of n−3 polyunsaturated fatty acids by solid phase extraction using aminopropyl bonded silica columns. After applying mixtures of fatty acid esters in hexane, saturated and monounsaturated fatty acid esters are preferentially eluted with hexane whereas polyunsaturated fatty acids (PUFA) can subsequently be eluted with dichloromethane. Concentrates containing 80–90% n−3 PUFA can thus be obtained using fish oil fatty acids esters as a starting material.
Release of lipoprotein lipase from cardiac myocytes by low‐molecular weight heparin
Authors: Braun J. E. A. , Severson D. L. 
Published: November 2006

AbstractIncubation of cardiac myocytes from rat heart with low‐molecular weight heparin (LMWH; Mr approx. 3 kDa) for 30 min resulted in a concentration‐dependent release of lipoprotein lipase (LPL) activity into the incubation medium. The release of lipoprotein lipase from cardiac myocytes isolated from both control and diabetic rat hearts induced by LMWH (10 μg/mL) following incubation times of 10 or 30 min was significantly greater than that produced by unfractionated heparin (10 and 30 μg/mL) or decavanadate (1 mM). Since LMWH released more LPL activity into the incubation medium than unfractionated heparin following a short (10 min) incubation time, LMWH is probably more effective in displacing LPL bound to heparan sulfate proteoglycan binding sites on the cell surface of cardiac myocytes.
Effect of simvastatin on desaturase activities in liver from lean and obese zucker rats
Authors: Georges B. , Blond J. P. , Maniongui C. , Bézard J. 
Published: November 2006

AbstractThe effect of simvastatin, a hypocholesterolemic drug, on the biosynthesis of arachidonic acid was studied in obese and lean Zucker rats. After administration of 2 mg/kg body weight/d for 13 d, Δ6 and Δ5 desaturase activities were measured in liver microsomes at two substrate concentrations. In untreated rats, the Δ6 desaturation rate was similar in the obese and lean rats when measured at saturating substrate levels, whereas Δ5 desaturation was lower in the obese animals. Treatment with simvastatin did not change Δ6 desaturation in either phenotype but increased Δ5 desaturation in obese rats to reach the unchanged rate observed in lean animals. The changes were not reflected in the fatty acid composition of liver microsomal phospholipids when expressed as μg fatty acid/g of liver.
A simple and efficient synthesis of fatty thioacids
Authors: Shin Hyeon‐Cheol , Quinn Daniel M. 
Published: November 2006

AbstractA rapid and high‐yielding two‐step synthesis of fatty thioacids from readily available staring materials has been devised. In the first step, an acid chloride is reacted with thioacetic acid at room temperature to produce a mixed thioanhydride, which in the second step is nucleophilically deacetylated with propylamine or butylamine at 5°C. Each step is complete in five minutes and proceeds in quantitative yield. The versatility of the procedure is demonstrated by the synthesis of fatty thioacids from six to sixteen carbons in length.
Characterization of a cytosolic protein in rat liver inhibiting neutral cholesteryl ester hydrolase
Authors: Shand J. H. , West D. W. 
Published: November 2006

AbstractNeutral cholesteryl ester hydrolase activity (EC 3.1.1.13) present in microsomes isolated from lactating rat mammary glands was found to be inhibited by a factor (or factors) occurring in the cytosolic fraction of male rat liver. The inhibitor was heat‐labile, non‐dialyzable, destroyed by proteolysis, and was stable following preparation of an acetone/diethyl ether powder of the cytosolic fraction. The protein also inhibited the activity of hormone‐sensitive lipase (HSL) (from bovine adipose tissue) and esterase fromCandida cylindracea, but seemed to be more active against the neutral hydrolase found in rat liver microsomes. For the mammary gland microsomal cholesteryl ester hydrolase, the extent of the inhibitory effect was dependent on the concentration of the cytosolic protein, 50% inhibition being achieved by about 100 μg of cytosolic protein, and on the method of initiating the enzyme assay. Kinetic analysis indicated that, under circumstances where the reaction was initiated by the addition of substrate, the inhibition was characterized as “uncompetitive”. When an inhibitor/substrate complex was allowed to form in the absence of enzyme, an element of “competitive” inhibition was introduced into the reaction. Food withdrawal reducted the activity of the inhibitor in live by 56%, but activity was fully restored by short‐term re‐feeding. In contrast, feeding a diet high in fat led to a 34% increase in activity. The present findings suggest that the inhibitory factor(s) may be involved in the regulation of the hydrolysis of cholesteryl esters in the liver and also in other cell types.
The inhibition of neutral cholesteryl ester hydrolase by a cytosolic protein factor in female rat liver: The influence of varying hormonal and nutritional conditions on the inhibitory activity
Authors: Shand J. H. , West D. W. 
Published: November 2006

AbstractA cytosolic protein, that is inhibitory to neutral cholesteryl ester hydrolase, has been investigated in the livers of female rats using microsomes isolated from the mammary gland of lactating rats as an enzyme source. To facilitate comparisons, inhibitory activity is expressed in terms of the amount (μg) of cytosolic protein required to reduce esterase activity by 50% and is compared to the hepatic content of both cholesterol and cholesteryl esters. The experiments revealed a sexual difference in the level of inhibitory activity, with the livers of both suckling and mature male animals containing less of the material than the corresponding females. Alterations in the physiological status of the females, such as pregnancy and lactation, led to a decrease in the activity of the protein. This was reversed by blocking lactation with a combination of an antiserum to rat growth hormone and the anti‐prolactin drug, bromcoriptine, but not by premature weaning of the animals. Food withdrawal for 24 hr also had the effect of increasing inhibitory activity. In general the cholesteryl ester content of the livers correlated with the level of inhibitory activity. Thus the activity of the cytosolic inhibitor of neutral cholesteryl ester hydrolase responded to changes in both the hormonal and the nutritional status of the female animal. It is suggested that the presence of the greater cholesteryl ester hydrolase inhibitory activity in the female liver may help to explain the lower risk of coronary heart disease in premenopausal females by facilitating increased hepatic storage of the sterol in the form of the ester.
Cholestane as a digestibility marker in the absorption of polyunsaturated fatty acid ethyl esters in Atlantic salmon
Authors: Sigurgisladottir Sjofn , Lall Santosh P. , Parrish Christopher C. , Ackman Robert G. 
Published: November 2006

AbstractSalmonid fish require long‐chain n−3 fatty acids in their diet. The digestibility of different chemical forms of fish oil fatty acids, fed as triacylglycerols, free fatty acids or ethyl esters, was examined in 300 g farmed Atlantic salmon (Salmo salar) using cholestane as an indicator of fat absorptionin lieu of the chromium oxide (Cr2O3) which is commonly used as a marker in digestibility studies. It was established that the two digestibility markers gave similar results. Conveniently, cholestane does not require a separate analysis if fatty acids are to be determined by appropriate gas‐liquid chromatography. The long‐chain polyunsaturated fatty acids were particularly well absorbed, the apparent digestibility being 90–98% when feeding triacylglycerols or free fatty acids. However, the digestibility of monounsaturated fatty acids (75–94%) was lower, and lower still for saturated fatty acids (50–80%). Ethyl esters of fatty acids were significantly less well absorbed (P<0.05) than were the corresponding fatty acids in free acid or triacylglycerol form. Irrespective of dietary fat type, only free fatty acids were identified in feces, indicating total hydrolysis of triacylglycerols and ethyl esters.
Comparison of the effects of dietary fish oils with different n−3 polyunsaturated fatty acid compositions on plasma and liver lipids in rats
Authors: Banerjee I. , Saha S. , Dutta J. 
Published: November 2006

AbstractThe effects of dietary fish oils with different n−3 polyunsaturated fatty acid compositions on plasma lipid profiles in rats have been studied. Forty‐eight male rats, previously maintained on a cholesterol‐free diet for 15 days, were fed for 60 days with diets supplemented with 10% fat of either marine hilsa fish (Hilsa ilisa, family clupeidae) or fresh‐water chital fish (Notopterus chitala, family notopteridae). The diets had similar levels of total saturated (35–41%), monounsaturated (43–47%) and n−3 polyunsaturated (9–10%) fatty acids. Cholesterol contents of the diets were adjusted to 0.85%; γ‐linolenic acid (3.3%) in chital oil and eicosapentaenoic acid (4.9%) in hilsa oil diets were the major n−3 contributors. The percentage of eicosapentaenoic acid in the chital oil diet was 0.57 times that of the hilsa oil diet, but the eicosapentaenoic (EPA) to arachidonic acid (AA) ratio in the latter (4.08) was 3.2 times that of the former (1.27). Sixty days of hilsa oil diet feeding decreased the levels of cholesterol (53.3±2.9 to 50.0±1.1 mg/dL), triacylglycerol (75.7±3.8 to 64.3±2.6 mg/dL) and phospholipid (55.8±1.5 to 51.7±3.1 mg/dL) in rat plasma. Similar treatment with chital oil diet elevated the plasma cholesterol level (53.3±2.9 to 62.3±7.6 mg/dL) while triacylglycerol and phospholipid contents remained unaltered. Both the dietary treatments decreased the levels of linoleic and arachidonic acids in liver but only under the hilsa oil diet did the eicosapentaenoic acid percentage increase markedly (0.8±0.06% to 5.5±0.06%) at the expense of arachidonic acid. This study strongly suggests that the hypolipidemic effect depends on the composition of the n−3 polyunsaturated fatty acids rather than on the total n−3 polyunsaturated fatty acid content of the dietary fish oil.
Characterization of triacylglycerols in the seeds ofAquilegia vulgaris by chromatographic and mass spectrometric methods
Authors: Demirbüker Mustafa , Blomberg Lars G. , Olsson N. Urban , Bergqvist Magnus , Herslöf Bengt G. , Alvarado Jacobs Fernando 
Published: November 2006

AbstractA combination of analytical techniques is generally necessary to properly characterize complex lipid materials. Chromatographic separation in conjunction with spectroscopic characterization was utilized for the analysis of the triacylglycerols in the seeds ofAquilegia vulgaris. Reversed‐phase high‐performance liquid chromatography (HPLC), micropacked argentation supercritical fluid chromatography (SFC), and combinations of the two techniques were used. The fatty acid profile was determined by gas chromatography/mass spectrometry of the picolinyl esters and by gas chromatography/flame‐ionization detection of the methyl esters. The major components were also identified by direct inlet mass spectrometry. The excellent selectivity of packed fused silica argentation SFC for the separation of triacylglycerols was demonstrated.
Triester glycerothiophosphates of cholecalciferol (vitamin D3)
Authors: Stamatov Stephan D. , Gronowitz Salo 
Published: November 2006

AbstractTris(N,N‐dimethyl)amide of phosphorous acid activated by addition of iodine at an optimal molar ratio of 1.05∶0.05 was used as a phosphorylating reagent to synthesize cholecalciferyl‐3‐O‐(1‐2‐isopropylidene‐rac‐glycero‐3‐O‐)‐thiophosphate and cholecalciferyl‐3‐O‐(1,2‐dipalmitoyl‐rac‐glycero‐3‐O‐)thiophosphate of methyl alcohol, 2‐dimethylaminoethanol, 3‐dimethylamino‐1‐propanol and 1,2‐isopropylidene‐rac‐glycerol in a “one‐pot procedure” in overall yields of 60–80%. Activation of the reaction with an equimolar mixture of imidazoeland carbon disulfide at the triester formation step permits selective phosphorylation at room temperature. The compounds synthesized represent new triester phospholipid model compounds in which (in addition to glycerol and another requisite alcohol) a steroid and an element other than oxygen are bond to phosphorus.
A colorimetric assay for measuring cell‐free and cell‐bound cholesterol oxidase
Authors: Kreit Joseph , Lefebvre Gérard , Elhichami Abdelhak , Germain Pierre , Saghi Mohamed 
Published: November 2006

AbstractCholesterol oxidase (cholesterol:oxygen oxidoreductase, EC 1.1.3.6) catalyzes the conversion of sterol Δ5‐3β‐alcohol to the corresponding Δ4‐3‐ketone with the reduction of oxygen to hydrogen peroxide.Rhodococcus species GK 1, a soil isolated microbe, produces an extracellular and a membrane‐bound cholesterol oxidase; the latter is bound to the outer surface of the microbial cell membrane. A simple and sensitive assay is described to measure the two enzyme types; no enzyme extraction is needed for measuring the membrane‐bound cholesterol oxidase. In this assay, hydrogen peroxide is reduced by the chromogen 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS) in the presence of horseradish peroxidase, and the increased absorbance is followed continuously at 600 nm (εm = 1.82×104 M−1·cm−1 at pH 7.0 and 30°C). The standardized assay medium contained 46.9 mM sodium‐potassium phosphate buffer pH 7.0, 0.16% Triton X‐100, 312.5 μM ABTS, 50 μg peroxidase (12.5 units at 25°C), 6.25% isopropanol, 306.3 μM cholesterol or other sterols (kept in solution with isopropanol), and cholesterol oxidase. Oxidation of one molecule of cholesterol by cholesterol oxidase gives one molecule of hydrogen peroxide which reacts with two molecules of ABTS. The method is reproducible and the results correlate well with those obtained by measuring the absorbance of Δ4‐cholest‐3‐one at 240 nm (εm = 1.40×104 M−1·cm−1 at pH 7.0 and 30°C) and by the method of Allainet al. (Clin. Chem. 20, 470–475, 1974). In terms of efficiency, simplicity, and time saved, this coupled assay is expected to be a useful method for monitoring microbial production of cholesterol oxidase on an industrial scale, and for determining cholesterol or other sterols in biological fluids.
The effect of amino acids on choline uptake and phosphatidylcholine biosynthesis in mammalian hearts
Authors: Chan Monroe , Karmin O , Man Adrian S. , Choy Patrick C. 
Published: November 2006

AbstractThe uptake of choline in mammalian hearts in the presence of amino acids was examined. Isolated hamster, guinea pig, rat and rabbit hearts were perfused with labeled choline in the presence and absence of amino acids. Neutral amino acids enhanced choline uptake in the hamster heart, but not in the guinea pig, rat and rabbit hearts. Phosphatidylcholine biosynthesis in these hearts was not affected by the presence of amino acids. Choline uptake in the hamster myocytes was also enhanced by neutral amino acid. The enhancement of choline uptake suggests a direct interaction between the amino acid and the transport of choline into the myocardiac cells. The different responses in choline uptake to neutral amino acids indicate that the regulation of choline uptake in the hearts may be different between mammalian species.
Changes in lipid content, fatty acid composition and lipoprotein lipase activity in dry goat omental adipose tissue according to tissue site
Authors: Bas P. , Gallouin F. , Morand‐Fehr P. 
Published: November 2006

AbstractWater and lipid contents, fatty acid distribution, and lipoprotein lipase activity were determined in 11 samples taken from theOmentum Majus of five dry Alpine goats. Samples were chosen to standardize sampling sites using geometric guide marks representative of different adipose tissue sites. Sample location explained between 20% and 30% of the total variance in water and lipid contents and in lipoprotein lipase activity, and from 5.5% to 45.4% of the total variance in fatty acid distribution. Increased sample thickness was associated with an increase in lipid content and in saturated fatty acid percentages. Samples taken in proximity of the omentum tissue attached to the rumen and abomasum had the highest content. We furthermore found that the levels of 18∶2n−6, 18∶1n−7, and of branched chain fatty acids were high close to a pila of the rumen which also corresponded to high lipoprotein lipase activity. Concomitant high levels of 16∶1n−7, 17∶1n−8, and 18∶1n−9 may reflect high levels of Δ9 desaturase activity.
Effect of 25‐hydroxycholesterol on cholesteryl ester formation in Caco‐2 cells
Authors: Kusuhara Hidenobu , Shimada Osafumi , Inui Jun 
Published: November 2006

AbstractIncubation of Caco‐2 cells, a human intestinal cell line, with 25‐hydroxycholesterol (25‐HOC) markedly enhanced cellular cholesteryl ester formation determined by incorporation of [14C]oleic acid into intracellular cholesteryl [14C]oleate. The stimulation by 25‐HOC of cholesteryl ester formation was suppressed by staurosporine, a kinase inhibitor, but not by cycloheximide or actinomycin D. The specific activity of microsomal acyl‐coenzyme A:cholesterol acyltransferase (ACAT) increased two‐fold in cells treated with 10 μM 25‐HOC for 5 h. ACAT activity decreased when microsomes were incubated without sodium fluoride, a phosphatase inhibitor, but the decrease in ACAT activity in cells stimulated with 25‐HOC was more pronounced. The results suggest that protein phosphorylation may be involved in the stimulation of cholesteryl ester formation by 25‐HOC in Caco‐2 cells.
Analysis of exoskeleton triglycerides ofLeptinotarsa decemlineata say
Authors: Dubis Eligiusz , Poplawski Janusz , Wróbel Jerzy T. , Kúsmierz Józef , Maliński Edmund , Szafranek Janusz 
Published: November 2006

AbstractThe exoskeleton triglyceride fraction isolated from the Colorado beetle,Leptinotarsa decemlineata Say, was studied. Analysis of the hydrolysis products and direct capillary column gas chromatography showed that, apart from triglycerides, the fraction contained no diol lipids. The composition of the natural triacylglccerol mixture was assessed by gas chromatography and by field desorption and electron impact mass spectrometry. Triglycerides isolated from the Colorado beetle are typical glycerol triesters, with long chain (mainly oleic or palmitic) fatty acids. The structures of two major components (91%), i.e., trioleoyl glycerol and 1,2‐dioleoyl‐3‐palmitoyl glycerol, were determined.
A liquid crystalline phase in human intestinal contents during fat digestion
Authors: Holt Peter R. , Fairchild Beatrice M. , Weiss Jordan 
Published: November 2006

AbstractA viscous, gel‐like phase was found in ultracentrifuged human upper intestinal contents collected during rapid fat lipolysis. This “gel” phase was layered in the ultracentrifuge tube between the micellar and oil phase. The gel contained lipids typical of the micellar and not the oil phase. The concentration of these lipids was higher and the ratio of total bile salts to lipids was lower in the gel than in the micellar phase. The gel, unlike the micellar phase, was birefringent between crossed polarizers. These data demonstrate that lipids in this gel phase can form liquid crystals in the gut during fat digestion.