bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dexamethasone‐induced alterations in the glycosphingolipids of rat kidney
Authors: Dahiya Rajvir , Brasitus Thomas A. 
Published: November 2006

AbstractTo determine whether glucocorticoids would influence the glycosphingolipid composition of the rat kidney, male albino rats of the Sherman strain were subcutaneously administered dexamethasone (100 μg/100 g body wt/day) or diluent for four days. The compositions of ceramide and of acidic and neutral glycosphingolipids of the kidneys of these animals were then examined and compared. The results demonstrated that dexamethasone administration: 1) increased the content of ceramide and of acidic and neutral glycosphingolipids in kidney; 2) increased the relative percentage of globotriaosyl‐ and globotetraosylceramide, but decreased the relative percentages of glucosylceramide; 3) decreased the relative percentages of GM3 and increased other gangliosides; 4) increased the relative percentages ofN‐glycolylneuraminic acid in GM3; 5) did not appear to influence significantly the long‐chain bases of the major glycosphingolipids; and 6) altered the relative percentages and chain length of the hydroxy and nonhydroxy fatty acids of the major acidic and neutral glycosphingolipids in this tissue. The data show that dexamethasone administration induces quantitative and qualitative changes in the glycosphingolipids of the rat kidney.
Accumulation of (n−9)‐eicosatrienoic and docosatrienoic acids in human fibroblast phospholipids
Authors: Karmiol Soverin , Bettger William J. 
Published: November 2006

AbstractAn essential fatty acid (EFA) deficiency‐like profile of fatty acids has been observed in HF‐1 human skin fibro‐blasts cultured at clonal densities in MCDB 110 and 0.4% fetal bovine serum (FBS). The profile was characterized by an accumulation of 16∶1n−7, 18∶1n−9, 20∶3n−9 and 22∶3n−9, a reduction of n−6 fatty acids and a reduction in total polyunsaturated fatty acids (PUFA). The fatty acid composition of sphingomyelin (SPH), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE) was determined and, except for SPH, each displayed an EFA deficiency‐like profile. The triene to tetraene ratio (20∶3n−9/20∶4n−6) ranged from 5.3 in PI to 0.9 in PE. In addition, the highest percentage of 20∶3n−9 was present in the PI and the highest percentage of 22∶3n−9, in PE. Other human fibroblasts (normal, transformed and at different population doubling number levels [PDL] were grown under the same conditions and were found to display triene to tetraene ratios (20∶3n−9/20∶4n−6) in total cellular lipids ranging from 0.7 to 4.5. The accumulation of 20∶3n−9 and 22∶3n−9 is due primarily to the existence of a basal nutrient medium (MCDB 110) that allows for the rapid clonal growth of human fibroblasts at reduced serum levels (0.4%). This culture procedure can be exploited to further elucidate various aspects of lipid metabolism in human fibroblasts.
Phospholipids from the free‐living nematodeCaenorhabditis elegans
Authors: Satouchi Kiyoshi , Hirano Kaoru , Sakaguchi Masamitsu , Takehara Hisaaki , Matsuura Fumito 
Published: November 2006

AbstractThe phospholipid and the fatty chain compositions of diacyl, alkylacyl and alkenylacyl glycerophospholipids of the free‐living nematode,Caenorhabditis elegans, were investigated. The phospholipids were comprised of 54.5% ethanolamine glycerophospholipid (EGP), 32.3% choline glycerophospholipid (CGP), 8.1% sphingomyelin and 5.1% others. The most abundant fatty acid in CGP was eicosapentaenoic acid (20∶5n−3). The fatty acids in CGP were more unsaturated than those in EGP. Alkenylacyl and alkylacyl subclasses accounted for 1.0 and 2.6%, respectively, of CGP and 14.0 and 19.6%, respectively, of EGP. At least 80% of the alkenyl and alkyl groups were 18∶0 chains and the remaining were odd numbered chains. The potential presence of platelet‐activating factor (PAF) was examined by bioassay, but PAF‐like activity was not detected in the extracts of this nematode.
Effect of some potassium selective crown ethers on the permeability and structure of a phospholipid membrane
Authors: Szögy M. , Cerhati T. , Tölgyesi F. 
Published: November 2006

AbstractThe effect of some new crown ethers on the cation efflux and phase transition parameters of dipalmitoyl phosphatidylcholine liposomes was studied. The effects were correlated with the lipophilicity of the crown ethers. The results indicate that the presence of two crown ring structures in one crown ether molecule is a prerequisite for the increase of ion permeability of liposomes. The effective crown ethers decrease the temperature, enthalpy and cooperativity of the gel‐to‐liquid crystalline phase transition. The crown ethers increase membrane permeability for potassium and, to a lesser extent, for rubidium and sodium. The ratio of permeability increase for potassium/rubidium significantly correlates with the lipophilicity of the crown ethers.
Continuous monitoring of lipid peroxidation by measuring conjugated diene formation in an aqueous liposome suspension
Authors: Vossen Renée C. R. M. , van Dam‐Mieras Maria C. E. , Hornstra Gerard , Zwaal Robert F. A. 
Published: November 2006

AbstractA method is described for the direct and continuous monitoring of lipid peroxidation in an aqueous suspension of sonicated liposomes. By means of ultraviolet difference spectroscopy using tandem cuvettes, the formation of conjugated dienes during liposome peroxidation can be followed. Using this technique, the effect of the fatty acid composition of liposomes on lipid peroxidation can be studied. The results show that both the extent and the time scale of lipid peroxidation are influenced by the fatty acid composition of the phospholipid liposomes. This was confirmed also by other methods, such as measurement of the formation of lipid hydroperoxides and measurement of the decrease in polyunsaturated fatty acids. The advantage of the method described is the direct and continuous monitoring of phospholipid peroxidation in an aqueous environment, without subsampling and extraction of peroxidation products into organic solvents. Using this experimental approach based on difference spectra the contributions from changes in liposome, CuSO4 and H2O2 concentrations are canceled, thus improving sensitivity. The method can be employed for measuring the susceptibility to peroxidation of membrane phospholipids from fatty acid modified endothelial cells.
Effects of non‐β‐oxidizable sulfur‐substituted fatty acid analogues on synthesis and secretion of triacylglycerol and cholesterol in cultured rat hapatocytes
Authors: Skorve Jon , Rustan Arild C. , Berge Rolf K. 
Published: November 2006

AbstractThe mechanisms behind the hypolipidemic effect of two sulfur‐substituted fatty acid analogues, 3‐thiadicarboxylic acid and tetradecylthioacetic acid, have been investigated in cultured hepatocytes. There was a dose‐dependent reduction in incorporation of [3H]water into triacylglycerol and diacylglycerol when tetradecylthioacetic acid was added to rat hepatocytes cultured in the presence of 200 μM oleic acid. Tetradecylthioacetic acid also increased the oxidation of [14C]palmitic acid compared to oleic acid, inhibited the incorporation of radiolabeled precursors into diacylglycerol to a greater extent than into triacylglycerol, and reduced the secretion of triacylglycerol more than its synthesis. A stimulation, rather than a reduction, in glycerolipid synthesis and secretion by tetradecylthioacetic acid was observed when oleic acid was omitted from the culture medium. When 3‐thiadicarboxylic acid was added to cultured hepatocytes, the effects on glycerolipid synthesis were generally similar to those observed with tetradecylthioacetic acid, but 3‐thiadicarboxylic acid did not increase the oxidation of [14C]palmitic acid. The two fatty acid analogues also had different effects on the synthesis and secretion of cholesterol and cholesteryl esters—3‐thiadicarboxylic acid reduced the incorporation of [3H]water into synthesized and secreted cholesterol and cholesteryl esters, whereas tetradecylthioacetic acid only reduced the secretion of cholesteryl esters without affecting its synthesis. It is concluded that tetradecylthioacetic acid increases the oxidation of fatty acids and reduces the synthesis and secretion of glycerolipids. 3‐Thiadicarboxylic acid reduces the synthesis and secretion of both glycerolipids and cholesterol to approximately the same extent without a concomitant increase in the oxidation of fatty acids.
The rare caribbean spongeLeucosolenia canariensis: Phospholipid fatty acids and sterols
Authors: Carballeira Néstor M. , Shalabi Fathi 
Published: November 2006

AbstractThe phospholipid fatty acid composition of the Calcarean spongeLeucosolenia canariensis was studied, and no Δ5,9 fatty acids were detected. These results are in contrast to the phospholipids from sponges belonging to the class Demospongiae where Δ5,9 fatty acids are predominant. Odd branched‐chain fatty acids between 17 and 19 carbons accounted for 26% of the total fatty acids ofL. canariensis, while straight‐chain fatty acids between 16 and 22 carbons accounted for 61% of the total fatty acid composition. The sterol composition ofL. canariensis is also reported, and only Δ5,7,22 sterols were observed.
Differential and interactive effects of calcium channel blockers and cholesterol content of the diet on jejunal uptake of lipids in rabbits
Authors: Hyson D. A. , Thomson A. B. R. , Kappagoda C. T. 
Published: November 2006

AbstractThe present study was undertaken to determine the effects of two classes of calcium channel blockers (CCB), nisoldipine (N) and verapamil (V), on the jejunal uptake of lipids in rabbits. The uptake of cholesterol and long‐chain fatty acids into rabbit jejunum was examined after 6 and 36 min of exposure to N or Vin vitro (“acute” studies), and after 3‐wk feeding of N or V (“chronic” studies). Animals were fed either a low (0.08%) cholesterol diet (LCD) or a high (2.8%) cholesterol diet (HCD), with or without N or V added. Acutein vitro exposure of the jejunum to N or V did not affect the uptake of cholesterol or palmitic acid in rabbits fed LCD or HCD. The effect of N or V feeding depended upon the cholesterol content of the diet; adding N or V to LCD increased cholesterol uptake while adding N or V to HCD enhanced or lowered cholesterol uptake, respectively. Both N and V increased the uptake of stearic acid in LCD. N in HCD had no effect on fatty acid uptake, whereas V lowered the uptake of stearic and linoleic acids and increased the uptake of oleic acid. These changes in lipid uptake were not due to variation in the animals' food intake, body weight gain, or intestinal mucosal surface area. The chronic administration of N or V results in an intestinal adaptive process that alters the jejunal uptake of lipids, the direction of which is influenced by the class of CCB, and by the cholesterol content of the diet. The serum lipid‐lowering effect of administering N to rabbits fed HCD demonstrated previously is unlikely to be the result of a decrease in intestinal lipid uptake.
Δ22‐β‐Muricholic acid in monoassociated rats and conventional ratsacid in monoassociated rats and conventional rats
Authors: Kayahara Takayuki , Tamura Toshihide , Amuro Yoshiki , Higashino Kazuya , Igimi Hirotsune , Uchida Kiyoshisa 
Published: November 2006

AbstractBile acids were analyzed in the bile, small and large intestines, and feces of germ‐free rats after a single inoculation with one of six intestinal bacteria that had been originally isolated from human feces.Bacteroides vulgatus andBifidobacterium longum preferentially deconjugated tauro‐β‐muricholic acid and taurocholic acid, respectively.Clostridium ramosum, Peptostreptococcus productus andLactobacillus gasseri deconjugated both bile acids, butEscherichia coli did not deconjugate either one. Rats inoculated with bacteria that deconjugated tauro‐β‐muricholic acid produced Δ22‐β‐Muricholic acid in the feces. In contrast, Δ22‐cholic acid could not be detected in rats inoculated with bacteria that deconjugated taurocholic acid.
Autoxidation of polyunsaturated triacylglycerols. IV. Volatile decomposition products from triacylglycerols containing linoleate and linolenate
Authors: Frankel E. N. , Selke E. , Neff W. E. , Miyashita K. 
Published: November 2006

AbstractTrilinoleoylglycerol (LLL), trilinolenoylglycerol (LnLnLn) and four synthetic triacylglycerols were autoxidized and the volatile products were investigated to determine the effect of fatty acid glyceride position on the mechanism of hydroperoxide decomposition. Capillary gas chromatography provided a sensitive method to follow the volatile oxidation products of mixtures of LLL and LnLnLn and of synthetic triacylglycerols containing linoleate and linolenate in different known positions. The relative amount of linoleate oxidation was determined by analyzing for hexanal, 2‐heptenal and 2,4‐decadienal, and the relative amount of linolenate oxidation by analyzing for 2,4‐heptadienal and 2,4,7‐decatrienal. The volatiles from pure monohydroperoxides of LLL and LnLnLn were compared with those of the corresponding triacylglycerols by capillary gas chromatography. Significant differences in the distribution of volatile products were observed depending on the triacylglycerols precursor. A 1∶1 mixture of LLL and LnLnLn autoxidized at 40°C showed an equal contribution of linolenate and linoleate volatiles at a peroxide value of 34. The synthetic triacylglycerols LLnL and LLLn (L, linoleic; Ln, linolenic acid) formed initially about the same total volatiles, whereas LnLnL formed more volatiles than LnLLn. The ratio Ln to L volatile products was the same for the diL triacylglycerols, and higher for LnLnL than for LnLLn. This new information should permit us to better understand the influence of triacylglycerol structure on the relative oxidative stability of unsaturated triacylglycerols.
Separation of underivatized gangliosides by ion exchange high performance liquid chromatography
Authors: Whalen Marge M. , Wild Gaynor C. , Spall W. Dale , Sebring Robert J. 
Published: November 2006

AbstractA procedure is described which separates neutral glycolipids from gangliosides, and which separates the gangliosides into classes, based on their number of sialic acid residues. In addition to separation into mono‐, di‐ and trisialoganglioside classes, there is purification of individual disialoganglioside species. The procedure uses a commercially available—NH2 high performance liquid chromatography (HPLC) column, which normally is used as an adsorption column. In this method the column is modified by protonation, to pH 5.4, so that it exhibits ion exchange as well as adsorption properties. Sensitive, nondestructive detection of eluent peaks is accomplished by monitoring continuously at 210 nm, a wavelength near which underivatized glycosphingolipids have absorbance maxima and which also will clearly detect most possible contaminants. An entire run, including re‐equilibration of the column, takes two hours.
Sterol pathway in yeast. Identification and properties of mutant strains defective in mevalonate diphosphate decarboxylase and farnesyl diphosphate synthetase
Authors: Chambon Christophe , Ladeveze Veronique , Servouse Madeleine , Blanchard Laurence , Javelof Catherine , Vladescu Barbu , Karst Francis 
Published: November 2006

AbstractYeast mutant strains auxotrophic for ergosterol and blocked in mevalonate diphosphate decarboxylase (erg19) and farnesyl diphosphate (FPP) synthetase (erg20) were isolated. The main feature of the mutants blocked in FPP synthetase is their ability to excrete prenyl alcohols, such as geraniol and farnesol. The isolation of the functionalERG20 gene allowed us to show that farnesyl diphosphate synthetase could be a rate limiting enzyme in ergosterol biosynthesis in yeast.
Effects ofbis homoallylic and homoallylic hydroxyl substitution on the olefinic13C resonance shifts in fatty acid methyl esters
Authors: Pfeffer Philip E. , Sonnet Philip E. , Schwartz Daniel P. , Osman Stanley F. , Weisleder David 
Published: November 2006

AbstractSubstitution of a hydroxyl group at thebis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73±0.05 ppm upfield and a 0.73±0.06 ppm downfield shift on the δ and ε olefinic13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of thebis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [|1.46+|Δδdbu‖] where Δδdbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the δ and ε shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [|1.46−|Δδdbu‖]. In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the γ and δ induced hydroxyl shifts for thecis double bond resonances are +3.08 and −4.63 ppm, respectively while thetrans double bond parameters are +4.06 and −4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [|7.71−|Δδdbu‖] forcis and [|8.24−|Δδdbu‖] for thetrans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations forcis andtrans isomers are [|7.71+|Δδdbu‖] and [|8.24+|Δδdbu‖], respectively. The derived shift parameters can verify the positions of both the double bond and hydroxyl substitution from the olefinic resonance separation in long‐chain fatty acid derivatives, obviating the need for destructive analytical methods.
Effect of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibition on human gut mucosa
Authors: Gebhard Roger L. , Ewing Stephen L. , Schlasner Linda A. , Hunninghake Donald B. , Prigge William F. 
Published: November 2006

AbstractMevalonic acid is an important biochemical intermediate in cholesterol synthesis and other processes involved in cell replication. 3‐Hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase is the enzyme which catalyzes mevalonic acid synthesis. To determine whether a potent competitive inhibitor of this enzyme, the drug simvastatin, may have an adverse effect on enterocyte cell replication and cholesterol metabolism, small intestinal biopsies from nine hypercholesterolemic subjects were obtained before and during treatment with simvastatin as a lipid‐lowering agent. Histologic review of biopsies in a blinded manner detected no change in ratio of villous length to crypt length or in mitotic index which might indicate altered cell replication. Similarly, no significant change in measured activity of HMG‐CoA reductase activity was observed. In spite of the high exposure of jejunal mucosal cells to this potent competitive inhibitor of a key enzyme, no adverse effect on growth could be detected.
The essential oil fromTagetes minuta L. modulates the binding of [3H]flunitrazepam to crude membranes from chick brain
Authors: García Daniel A. , Perillo María A. , Zygadlo Julio A. , Martijena Irene D. 
Published: November 2006

AbstractThe hypothesis that the essential oil fromTagetes minuta L. can interact with biological membranes was investigated by assessing its ability of perturbing the binding of a benzodiazepine [flunitrazepam (FNTZ)] to crude membranes from chick brains. The essential oil fromT. minuta L. inhibited [3H]FNTZ specific binding to chick brain membranes. These values were obtained from the analysis of the saturation curve for the kinetic parameters: dissociation equilibrium constant (Kd)=2.47±0.32 nM, maximal binding (Bmax)=556±5 fmoles/mg protein, and Hill coefficient (n)=1.00±0.07 in the absence, and Kd=6.73±1.4 nM, Bmax=583±69 fmoles/mg protein, and n=1.02±0.08 in the presence of 29 μg/mL of essential oil. The essential oil could self‐aggregate with a critical micellar concentration (CMC) of 60 μg/mL. The marked increase in [3H]FNTZ nonspecific binding starting at 60 μg of essence per mL was due to that phenomenon and revealed the ability of self‐aggregated structures to interact with membranes. [3H]FNTZ specific binding decrement as a function of essence concentration cannot be ascribed merely to oil's micelles ability of trapping the lipophilic radioligand molecules, because the discontinuous behavior that characterizes a monomer‐aggregate phase transition was not shown. Oil's components might behave as competitive inhibitors or allosteric modulators of FNTZ specific binding. However, their ability to increase FNTZ nonspecific binding at concentrations below oil's CMC suggests that this effect may be due to oil's partitioning into the lipid bilayer. This latter phenomenon would induce an increment in membrane fluidity and a change on FNTZ binding site toward a lower affinity conformation. Therefore, the essential oil components can interact with brain membranes either as monomers, by partitioning into the lipid bilayer, or as self‐aggregated structures, through an adsorption to the membrane surface.
Metabolism of long‐chain fatty acids, alcohols and alkylglycerols in the fish parasiteParatenuisentis ambiguus (Acanthocephala)
Authors: Filipponi Christin , Taraschewski Horst , Weber Nikolaus 
Published: November 2006

AbstractSpecific differences between the acyl composition of lipids on the helminthParatenuisentis ambiguus and its host eel, as shown previously, prompted us to study the lipid metabolism in this intestinal fish parasite. Adults and larvae ofP. ambiguus were fed various lipid precursors, e.g., fatty acids, long‐chain alcohols and 1‐O‐alkylglycerols, which may occur as common nutrients of intestinal parasites. Incorporation of [1‐14C]palmitic acid into neutral and polar lipids was found to be similar under aerobic and near‐anaerobic conditions. In adult parasites maintained in culture medium supplemented with glucose, [1‐14C]palmitic acid was incorporated mainly into triacylglycerols and phosphatidylcholines, whereas [1‐14C]oleic acid was incorporated preferentially into triacylglycerols. In fasted adults, as well as in larvae, [1‐14C]oleic acid was mainly transferred to phosphatidylcholines. Lipolytic activity was detected in adult parasites that had been incubated with radioactive trioleoylglycerol. [1‐14C]Hexadecan‐1‐ol was oxidized inP. ambiguus at a high rate to labeled palmitic acid, which was incorporated into various lipid classes ofP. ambiguus. Small but significant proportions of radioactivity from hexadecan‐1‐ol were incorporated into ether glycerolipids of the parasite. A more direct precursor in ether glycerolipid metabolism, i.e.,rac‐1‐O‐[1′‐14C] hexadecylglycerol, was incorporated into alkyl and 1′‐alkenyl moieties of choline and etha‐nolamine etherglycerophospholipids ofP. ambiguus in high yield. High proportions of labeled diacylglycerols, triacylglycerols and steryl esters were detected in surface lipids as well as lipid extracts of the culture media after incubation ofP. ambiguus with [1‐14C]palmitic or [1‐14C]oleic acids. The results suggest that palmitic acid and oleic acid are incorporated into neutral and polar lipids ofP. ambiguus maintained in glucose medium quite differently with oleic acid showing a strong preference for triacylglycerols. However, the incorporation of palmitic acid in glucose‐fed parasites was similar to that of oleic acid in fasted parasites, as well as in larvae. This may be explained by partial fatty acid depletion in fasted worms and rapid cell division in larvae, respectively.