bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatty acid and cholesterol synthesis from specifically labeled leucine by isolated rat hepatocytes
Authors: Mathias Melvin M. , Sullivan Ann C. , Hamilton James G. 
Published: December 2006

AbstractHepatocytes isolated from female rats meal‐fed a high‐glucose diet were incubated in Krebs‐Henseleit bicarbonate medium containing 16.5 mM glucose,3H2O, and14C‐labeled amino acids (−)‐Hydroxycitrate depressed the incorporation of3H2O and [14C] alanine into fatty acids and cholesterol. Incorporation of [U‐14C] leucine into lipids was not affected but incorporation of3H2O into lipids was decreased significantly by (−)‐hydroxycitrate. (−)‐Hydroxycitrate depressed the incorporation of radioactivity from [2‐14C]leucine into fatty acids and cholesterol by 61 and 38%, respectively, and stimulated the incorporation of radioactivity from [4,5‐3H]leucine 35 and 28%. As [2‐14C]leucine labels the acetyl‐CoA pool and [4,5‐3H]leucine labels the acetoacetate pool, it was concluded that mitochondrial 3‐hydroxy‐3‐methylglutaryl‐CoA is not incorporated intact into cholesterol, and that acetoacetate can be activated effectively in the liver cytosol for support of cholesterol and fatty acid synthesis.
Metabolic discrimination between cholesterol and β‐amyrin byPhytophthora cactorum
Authors: Nes W. David , Saunders Gary A. , Heftmann Erich 
Published: December 2006

AbstractWhen cultures ofPhytophthora cactorum were incubated on solid medium for 3 weeks in the dark at 20 C with [14C] cholesterol or [14C]β‐amyrin, the [14C] cholesterol was assimilated into the advancing mycelium to a greater extent than the [14C]β‐amyrin. Examination of the mycelium and medium for radioactive metabolites showed significant differences in the metabolism of the 2 labeled compounds. Cholesterol was converted mainly to esters and to some extent to glycosides, whereas β‐amyrin was only slightly converted to esters and not at all to glycosides.
Aqueous lipid phases of relevance to intestinal fat digestion and absorption
Authors: Lindström Mats , Ljusberg‐Wahren Helena , Larsson Kåre , Borgström Bengt 
Published: December 2006

AbstractThe phase behavior of monoglyceride/water systems, with oleic and linoleic acid as the dominating fatty acid residues, was investigated. Increased solubilization of triglycerides (oil) or oleic acid in the cubic liquid‐crystalline phase formed by monoglyceride and water resulted in the formation of a reversed hexagonal liquid‐crystalline phase followed by an L2‐phase. The liquid‐crystalline phases have different dispersion properties compared to each other in dilute micellar bile salt solutions. The cubic phase is found to be easily dispersed. The relevance of aqueous lipid phases other thah micellar is discussed in relation to intestinal lipid digestion and absorption.
A nondestructive spray reagent for the detection of prostaglandins and other lipids on thin layer chromatograms
Authors: Goswami S. K. , Kinsella J. E. 
Published: December 2006

AbstractThe spray reagent 8‐hydroxy‐1,3,6‐pyrenetrisulfonic acid trisodium salt (10 mg/100 ml methanol) is extremely sensitive for locating prostaglandins on thin layer chromatograms. This reagent does not alter the PG, nor interfere with liquid scintillation counting.
A 2‐phase liquid scintillation assay for glycolipid synthetases
Authors: Hospattankar Ashok V. , Radin Norman S. 
Published: December 2006

AbstractGlycolipid synthetases can be assayed conveniently by incubating the lipid substrate with the radiosugar‐labeled nucleotide in a small plastic scintillation vial. At the end of the incubation period, water and perchloric acid are added, thenn‐butanol, then a toluene‐based scintillation cocktail. The radioactive lipid partitions into the scintillation fluid, leaving excess sugar nucleotide in the aqueous phase. Only a small fraction of the total radioactivity in the aqueous layer is detectable. This method is illustrated for ceramide: UDP‐glucose glucosyltransferase. The approach should be applicable to other lipid synthetases that can be assayed with a radioactive hydrophilic substrate.
On the occurrence of α‐tocopherolquinone in rat tissue
Authors: Bieri John G. , Tolliver Teresa J. 
Published: December 2006

AbstractThe amount of α‐tocopherolquinone in rat liver has been reinvestigated comparing (a) a conventional procedure including saponification and thin layer chromatography followed by high peformance liquid chromatography (HPLC), with (b) the direct HPLC analysis of a total lipid extract. Recovery of added α‐tocopherolquinone was quantitative with both procedures. In contrast to a recent report of 124 nmol/g in rat liver, we found no more than 1–4 nmol/g by procedure a and less than 1 nmol/g by procedure b.
Effect of eicosatetraynoic acid on liver and plasma lipids
Authors: Wood Randall 
Published: December 2006

AbstractGroups of rats were fed a fat‐free diet supplemented with 0.5% safflower oil (control) or the control diet containing 0.5% of 5,8,11,14‐eicosatetraynoic acid (TYA). Blood was collected weekly and plasma lipids analyzed. After 4 weeks, the animals were killed and the liver lipids were analyzed in detail. The acetylenic fatty acid perturbed plasma neutral lipid and phospholipid class concentrations and reduced growth rates. Liver triglyceride concentrations were reduced dramatically in the TYA fed animals, suggesting interference with complex lipid synthesis. Plasma and liver triglycerides were shifted to higher molecular weight species suggesting that TYA affected fatty acid metabolism. The phospholipids showed an accumulation of 18∶2 and a fall in 20∶4 percentages indicating an inhibition in the conversion of linoleate to arachidonate. All major lipid classes exhibited an increase in 18∶1 levels. Analysis of the octadecenoate positional isomers indicated the proportion of oleate increased substantually in all lipid classes whereas vaccenate proportions had fallen dramatically. All of the data collectively suggest that TYA inhibits the elongation of unsaturated fatty acids. A group of rats bearing hepatoma 7288CTC were also fed the TYA diet. Host liver lipids were affected by TYA similar to normal TYA fed animals, but the effects on hepatoma lipids were marginal.
Effect of hepatoma on host liver, heart and lung lipids as tumor growth progresses
Authors: Wood Randall , Zoeller A. , Matocha M. 
Published: December 2006

AbstractA large group of rats was transplanted with hepatoma 7288CTC and 4 animals were sacrificed at 3‐day intervals for four weeks. Lipid class concentrations, fatty acid class compositions, and the distribution ofcis octadecenoate positional isomers in the major lipid classes were determined for heart, liver and lung at each time period. The hearts of host animals decreased in dry weight as hepatoma growth progressed. At day 30, heart weights were less than two‐thirds of initial weights. Lipid class concentrations changed in all three tissues: cholesterol and free fatty acids increased in liver; triglycerides and cholesterol decreased and then increased in heart; and cholesterol, triglycerides and PC decreased in lung as tumor growth progressed. Hexadecenoate percentages exhibited a progressive decrease in all the lipid classes of heart and liver. Although total octadecenoate percentages showed only minor changes, oleate concentrations generally increased and vaccenate levels decreased in heart and liver lipids as tumor growth progressed. Palmitoleate, precursor of vaccenate, exhibited decreased concentrations early that resulted in decreased vaccenate levels. Decreased palmitoleate concentrations suggest inhibition of the Δ9 desaturase system, but normal oleate concentrations complicate this interpretation. Most of the changes in the lipids were detectable 3–6 days after transplantation, indicating the hepatoma affects the lipid metabolism of the host animal early and well in advance of nutritional stresses.
Photosensitized oxidation of methyl linolenate. Secondary products
Authors: Neff W. E. , Frankel E. N. , Weisleder D. 
Published: December 2006

AbstractPrevious studies of secondary oxidation products by high‐pressure liquid chromatography (HPLC) of autoxidized methyl oleate, linoleate and linolenate and photosensitized‐oxidized linoleate are extended to photosensitized‐oxidized linolenate. Photosensitized‐oxidized linolenate was fractionated by silicic acid chromatography with diethyl ether/hexane mixtures. Selected silicic acid chromatographic fractions were separated by polar phase HPLC and characterized by thin layer and gas liquid chromatography and by ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Secondary products from the photosensitized oxidation mixtures (containing 8.2 to 29.0% monohydroperoxides) included keto‐ and epoxy‐dienes (0.4–1.6%), hydroperoxy epidioxides (0.8–4.9%), hydroperoxy bicyclic monoenes (0.1–0.3%), dihydroperoxides (1.0–5.6%), and hydroperoxy bisepidioxides (0.7–1.6%). Some of these secondary products are new and unique to photosensitized oxidation. Cyclization of the 10‐, 12‐, 13‐ and 15‐hydroperoxides of linolenate would account for their lower relative concentration than that found for the 9‐ and 16‐hydroperoxides. Dihydroperoxides may be derived from monohydroperoxides by singlet oxygenation or free radical oxidation. The hydroperoxy bis‐epidioxides may be formed by further serial cyclization of the hydroperoxy epidioxides from 10‐ and 15‐monohydroperoxides. Dihydroperoxides, hydroperoxy epidioxides and hydroperoxy bis‐epidioxides are suggested as important flavor precursors in oxidized fats.
Cholesterol metabolism in gnotobiotic gerbils
Authors: Bartizal Kenneth F. , Beaver Margaret H. , Wostmann Bernard S. 
Published: December 2006

AbstractGermfree gerbils were associated with a murine‐derived hexaflora which produced only minor changes in the primary bile acid pattern of rats. These hexaflora‐associated gerbils had relatively small ceca (4% of body weight) and reproduced well. Although serum cholesterol levels of both conventional and hexaflora‐associated gerbils increased in response to dietary cholesterol, the hexaflora‐associated gerbil showed a greater elevation in serum cholesterol than the conventional gerbil when maintained on a diet containing 0.1% cholesterol. This increase in serum cholesterol manifested itself almost totally in the very low density lipoprotein and low density lipoprotein fractions. The fecal bile acids of the hexaflora‐associated gerbil were largely deconjugated, but very little further modification of either cholic or chenodeoxycholic acid had taken place. The data suggest that in the absence of elements of the intestinal microflora that can express a bile acid‐modifying potential, and particularly a 7‐α‐dehydroxylating capacity, catabolism of cholesterol to bile acids is reduced, and cholesterol accumulates in the very low density and low density serum lipoprotein fractions.
Synthesis and identification of bis (diacylglycero) phosphoric acid and bis (monoacylglycero) phosphoric acid
Authors: Dang Quoc Quan , Rogalle Pierre , Salvayre Robert , Dousteblazy Louis 
Published: December 2006

AbstractSynthesis of bis‐(diacylglycero)phosphoric acid fromsn‐1,2‐dipalmitoylglycerol and phenylphosphoryl dichloride according to Baer (1) was revised. New data are reported about identification of the intermediate and final products: (a) bis‐phosphatidic acid phenyl ester is very slowly visualized by the Zinzade reagent and can escape notice; (b) large amounts of phosphatidic acid chloride phenyl ester are also formed; and (c) very little transacylation fromsn‐1,2‐dipalmitoyl‐glycerol to the 1,3‐isomer is observed. Hydrolysis of bis‐phosphatidic acid to bis‐lysophosphatidic acid is much easier using phospholipase A2 from pig pancreas than from snake or bee venom.
Increased thromboxane B2 biosynthesis in platelets
Authors: Kawaguchi H. , Ishibashi T. , Imai Y. 
Published: December 2006

AbstractThe synthesis of thromboxane B2 is increased in platelets from rabbits with experimental hypercholesterolemia, but the increase is not due to increased phospholipids hydrolysis. We have clarified the mechanism for the increased thromboxane synthesis. The biosyntheses of prostaglandin H2 and thromboxane B2 were unaffected by supperoxide dismutase, xanthine oxidase, mannitol, or benzoate in other experiments designed to study the possible involvement of reactive oxygen species. These results suggest that O2.− and OH. were not likely to be involved as intermediates in the synthesis of prostaglandin H2 and thromboxane B2 in platelets. The rate of prostaglandin H2 biosynthesis was promoted in deuterium oxide, and this deuterium oxide enhancement effect was reversed by 2,5‐diphenylfuran, suggesting that singlet oxygen may be involved in prostaglandin H2 biosynthesis. The biosynthesis of prostaglandin H2 was promoted by ADP‐Fe3+ but inhibited by EDTA and EDTA‐Fe3+. The effect of ADP‐Fe3+ could not be replaced by EDTA‐Fe3+. The effects of glutathione, glutathione peroxidase and H2O2 on cyclooxygenase and thromboxane synthetase were studied by using partially purified enzymes and platelet microsomes. Glutathione and glutathione peroxidase inhibited the activity of cyclooxygenase but did not inhibit that of thromboxane synthetase. H2O2 caused the inactivation of cyclooxygenase, but the addition of H2O2 did not inhibit the formation of thromboxane B2 from prostaglandin H2. An examination of glutathione concentration and glutathione peroxidase activity in platelets from normal and experimentally hypercholesterolemic rabbits demonstrated that both were decreased in platelets from later group. The observed alterations in glutathione levels and glutathione peroxidase activity are large enough to cause increased thromboxane B2 synthesis in platelets but the possibility that other unidentified factors may also contribute cannot be excluded.
Morphology and fatty acid composition of reticulocytes from phenylhydrazine‐treated rats
Authors: Goheen S. C. , Larkin E. C. , Rao G. Ananda 
Published: December 2006

AbstractReticulocytosis was induced in rats by injecting phenylhydrazine, a potent oxidizing agent. Red cell morphology was analyzed by scanning electron microscopy. The majority of red cells from rats given injections of phenylhydrazine were types 2 and 3 echinocytes. Stomatocytes were also observed, but pitted lobular reticulocytes were not detected. Echinocytes have not previously been observed in reticulocyte populations. In the reticulocytes, the relative levels of 16∶1 and 18∶1 were significantly greater than in erythrocytes. These differences in monoenoic acids may be due to the presence of endoplasmic reticulum, the site of desaturase activity in reticulocytes. Of all the fatty acids, the polyunsaturates are the most susceptible to attack during peroxidation. However, the polyunsaturated fatty acid composition of reticulocytes was similar both to that of erythrocytes and to reported values of young erythrocytes isolated by density. Therefore, it is unlikely that lipid peroxidation caused the formation of echinocytes.
Rat adipocyte utilization of different substrates: Effects of cell size and the control of lipogenesis
Authors: May James M. 
Published: December 2006

AbstractThe metabolism of labeled glucose, pyruvate and acetate was compared in adipocytes isolated from old, obese rats (>500 g) and young, lean rats (130–150 g). The larger cells from old, obese rats had markedly reduced rates of glucose, pyruvate and acetate conversion to glyceride‐fatty acids, indicating that large cell fatty acid formation is reduced at some point beyond the entry of pyruvate and acetate into glucose metabolism. No evidence of a primary block in the pentose phosphate cycle of cells from old, obese rats was found. In spite of diminished glucose metabolism to several products in the large cells, both basal and insulin‐stimulated rates of glyceride‐glycerol synthesis from glucose and pyruvate were similar in each cell type. This indicates a relative diversion of carbon flow to α‐glycerophosphate and reesterification in the large cells. Addition of low concentrations of glucose increased glyceride‐fatty acid synthesis from acetate (both cell types) or pyruvate carbon (small cells), but decreased glyceride‐glycerol synthesis from pyruvate carbon (both cell types). The acceleration of small cell fatty acid synthesis from pyruvate carbon by glucose and insulin was shown to be related to provision of NADPH from glucose metabolism in the pentose cycle. These studies indicate that, although the block in lipogenesis in adipocytes from old, obese rats appears to reside in the pathway of fatty acid synthesis itself, provision of additional α‐glycerophosphate or NADPH from glucose metabolism may, under certain conditions, increase lipogenesis in cells from old, obese and young, lean rats.
Cholesteryl ester hydrolase activity in adrenal homogenates from normal and essential fatty acid‐deficient female rats
Authors: Young Angela K. , Walker Brian L. 
Published: December 2006

AbstractCholesteryl ester hydrolase was assayed in adrenal homogenates from mature female rats fed a control (corn oil‐containing) or essential fatty acid (EFA)‐deficient diet. Cholesteryl ester of 16∶0, 18∶0, 18∶1, 18∶2(n−6), 20∶4(n−6) and 22∶4(n−6) were used as substrates. In control rats, the unsaturated esters were hydrolyzed more rapidly than the saturated esters and cholesteryl arachidonate was the preferred substrate of the six investigated; cholesteryl oleate elicited the highest activity in the deficient group. Polyunsaturated esters were hydrolyzed at a significantly lower rate by homogenates from EFA‐deficient rats than by those from control animals. The esters of 18∶1, 18∶2(n−6) and 20∶4(n−6) were hydrolyzed more extenstively in relation to their concentrations in adrenal tissue than were cholesteryl esters of 16∶0, 18∶0 and 22∶4(n−6). This difference was more pronounced in control than in EFA‐deficient rats. No simple relationship of adrenal cholesteryl ester hydrolase activity to ester fatty acid structure or to nutritional essentiality was evident.
Effect of detergents on in vitro 7α‐hydroxycholesterol formation by rat liver microsomes
Authors: Sanghvi Ajit , Grassi Enrico , Bartman Candace , Diven Warren F. 
Published: December 2006

AbstractFormation of 7α‐hydroxycholesterol by rat liver microsomes was quantitated using a gas chromatograph‐mass spectrometer (GC/MS) operated in selected ion monitoring (SIM) mode. Microsomes from normal rat livers incubated for different periods were found to yield increased 7α‐hydroxycholesterol with time. This was also true when incubations contained Tween‐80, but in this instance, the rate of 7α‐hydroxycholesterol production was lower and dependent on the concentration of Tween used. Similarly, Triton X‐100, Renex‐30, Kyro EOB, Cutscum, and Emulgen 911 all lowered the formation of 7α‐hydroxycholesterol by rat liver microsomes, whereas Triton WR‐1339 stimulated its production. Analysis of data obtained from following the enzyme reaction over an extended period using an integrated Michaelis‐Menten equation indicated the enzyme possesses a very significant affinity for the product (Ks>Kp). Similar analysis shows that Tween‐80 is a noncompetitive inhibitor of the enzyme.
The quantitative determination of plasmalogen by its reaction with mercuric chloride
Authors: Carey Eric M. 
Published: December 2006

AbstractThe alk‐1‐enyl group of 1‐alk‐11‐enyl‐2‐acyl‐glycerophospholipids (plasmalogens) rapidly combines with mercuric chloride. At 0 C, there was a 1∶1 stoichiometry for Hg binding to the reactive enol group of plasmalogens. Aldehydes were not released, indicating that the alkenyl ether bond was not cleaved. Hg binding to less reactive double bonds in unsaturated fatty acids was not significant. Quantitative estimation of bound Hg afforded a rapid and sensitive assay for alkenylacyl lipids and gave values similar to those obtained with other methods of analysis. The proportion of plasmalogens in bovine myelin glycerophosphatides and in ethanolamine glycerophosphatide was 35 and 75%, respectively. Plasmalogens account for 23.3% of the total glycerophospholipid of rat erythrocytes.
Effect of altered sterol composition on the osmotic behavior of sphaeroplasts and mitochondria ofSaccharomyces cerevisiae
Authors: McLean‐Bowen Colleen A. , Parks Leo W. 
Published: December 2006

AbstractThe effect of sterols on the osmotic stability of mitochondrial and plasma membranes of yeast wild‐types and mutants that are defective in ergosterol biosynthesis has been studied. Incorporation of the nonfungal sterol, cholesterol, into yeast membranes reduces membrane elasticity which is observed as an increased susceptibility to osmotic lysis. However, the wild‐type and nystatin‐resistant strains which were examined indicate that qualitative alterations in endogenously generated sterols do not affect resistance to swelling. Although these strains exhibit differences in membrane fluidity, which is influenced by the sterol accumulated by the organisms, the membrane stretching capacity shows no distinct dependence on sterol structure or bilayer fluidity.
Uptake and oxidation of malonaldehyde by cultured mammalian cells
Authors: Bird R. P. , Draper H. H. 
Published: December 2006

AbstractPrimary cultures of rat skin fibroblasts were used as a model system to investigate the cellular uptake and oxidation of malonaldehyde (MA). The cells were grown in a medium containing 10−5 M, 10−4 M or 10−3 M concentrations of [1,3‐14C]MA. There was a limited, concentration‐dependent uptake of MA by 24 hr (∼4% at all concentrations). The uptake of [1,2‐14C]acetate by 24 hr was ∼24%; 83–89% of the14C in the MA taken up was oxidized to14CO2 by 24 hr and ∼5% was recovered in the major lipids. Despite its low uptake and rapid oxidation to CO2, pretreatment of the cells with 10−3 M MA for 24 hr produced a latent inhibition of [14C]glucose oxidation. Limited cellular uptake of MA may explain the tolerance of cells grown in culture to relatively high MA concentrations.
Selective deposition oftrans‐8‐ andcis‐9‐octadecenoates in egg and tissue lipids of the laying hen
Authors: Lanser A. C. 
Published: December 2006

AbstractThe deposition oftrans‐8‐octadecenoate‐8(9)‐3H (8t‐18∶1‐3H) was compared tocis‐9‐octadecenoate‐10‐14C (9c‐18∶1‐14C) in the major egg yolk neutral lipids and phospholipids and in organ lipids from the laying hen.trans‐8‐Octadecenoate was preferentially incorporated into only the phosphatidylethanolamines (PE), whereas discrimination against 8t‐18∶1‐3H occurred in the phosphatidylcholines (PC), triglycerides (TG) and cholesteryl esters (CE). The 1‐acyl position of both PE and PC contained three times more 8t‐18∶1‐3H than 9c‐18∶1‐14C. Almost total exclusion of the 8t‐18∶1‐3H from the 2‐acyl position of these phospholipids was found. Preferential incorporation of 9c‐18∶1‐14C occurred at the combined 1‐ and 3‐acyl positions and at the 2‐acyl position of yolk TG. Tissue lipid analyses indicated that there was preferential deposition of 9c‐18∶1‐14C into all organs. Individual liver lipid classes displayed the same relative order of discrimination against 8t‐18∶1‐3H as did egg yolk lipids (CE>TG>PC>PE).