bluuebunny/crossref_metadata_2025_split huggingface dataset:
Action of cobra venom phospholipase A2 on large unilamellar vesicles: Comparison with small unilamellar vesicles and multibilayers
Authors: Kensil Charlotte Read , Dennis Edward A. 
Published: November 2006

AbstractPhospholipase A2 (Naja naja naja) catalyzes the hydrolysis of dipalmitoyl phosphatidylcholine in small unilamellar vesicles (SUVs) with a faster initial rate than in large unilamellar vesicles (LUVs) and multilamellar vesicles (MLVs). For the SUVs, the hydrolysis was initially faster for gel phase than liquid crystalline phase phospholipid. For both LUVs and MLVs, hydrolysis was low except in a small temperature range around the thermotropic phase transition of the phospholipid. In this temperature range, the reaction time course of phospholipase action on dipalmitoyl phosphatidylcholine in LUVs and MLVs included a lag period. With SUVs, a lag period also was observed above the phase transition temperature, but it was not observed below it.
Dealkylation of various 14‐alkylsterols by the nematodeCaenorhabditis elegans
Authors: Lozano Ruben , Lusby William R. , Chitwood David J. , Svoboda James A. 
Published: November 2006

AbstractThe metabolism of 4 dietary 24‐alkylsterols was investigated in the free‐living nematodeCaenorhabditis elegans. The major unesterified sterols ofC. elegans in media supplemented with either campesterol, 22‐dihydrobrassicasterol or stigmasterol included cholesta‐5,7‐dienol, cholesterol, cholest‐7‐enol, and 4α‐methylcholest‐8(14)‐enol. Dietary stigmastanol yielded cholest‐7‐enol, cholestanol, cholest‐8(14)‐enol, and 4α‐methylcholest‐8(14)‐enol as major unesterified sterols. Esterified sterols comprised less than 22% of the total sterol. Removal of a C‐24 ethyl substituent of sterols was neither hindered by the presence of a Δ22‐bond in the sterol side chain nor was it depedent on unsaturation in ring B of the steroid nucleus.C. elegans reduced a Δ22‐bond during its metabolism of stigmasterol; it did not introduce a Δ22‐bond during stigmastanol metabolism.C. elegans was capable of removing a C‐24 methyl substituent regardless of its stereochemical orientation. Metabolic processes involving the steroid ring system of cholesterol (C‐7 dehydrogenation, Δ5‐bond, 4α‐methylation, Δ8(14)‐isomerization inC. elegans were not hindered by the presence of a 24‐methyl group; various 24‐methylsterol metabolites from campesterol were detected, mostly 24‐methylcholesta‐5,7‐dienol. In contrast, no 24‐ethylsterol metabolites from the dietary ethylsterols were found. More dietary 24‐methylsterol remained unmetabolized than did dietary 24‐ethylsterol. A 24α‐ethyl group and a 24β‐methyl group were dealkylated to a greater extent byC. elegans than was a 24α‐methyl group, perhaps reflecting the substrate specificity of the dealkylation enzyme system, or suggesting different enzymes altogether.
Mass spectra of TMS esters of deuterated decanoic acids and of TMS ethers of deuterated decanols
Authors: Tulloch A. P. 
Published: November 2006

AbstractMass spectra of trimethylsilyl esters of nine specifically deuterated decanoic acids and of trimethylsilyl ethers of the corresponding deuterated decanols and of tri[2H3] methylsilyl derivatives of most of the acids and of decanol have been measured. The fragmentation patterns have been used to examine the formation of ions m/z 117, 129, 131, 132, 145, 159, 171, 185 and 201 in the spectrum of the TMS ester of decanoic acid. Mechanisms of breakdown of one ion to another have been proposed. Similarities and differences in ion formation between spectra of TMS esters and methyl esters have been examined. It has been shown that ion m/z 132 is produced by the McLafferty rearrangement and that ion m/z 117 is formed from it by loss of a silyl methyl group. Ion m/z 145 is formed by hydrogen transfer from C‐5, C‐6 or C‐7 to the carbonyl oxygen and γ‐cleavage. Ion m/z 129 is formed from ion m/z 145 by loss of the previously transferred hydrogen and a silyl methyl group. A mechanism of formation of ions m/z 115, 129, 143 and 157, which contained only one silyl methyl group, observed in the mass spectrum of the TMS ether of decanol, has been proposed. Ions in spectra of the derivatives can be used to locate the position of deuterium, or other substituents, at a number of the carbons of decanoic acid or decanol.
Effect of brominated vegetable oils on heart lipid metabolism
Authors: Lombardo Yolanda B. , Chicco Adriana , Basílico María Z. , Bernal Claudio , Gutman Raul 
Published: November 2006

AbstractNormal rats fed for 105 days on an experimental diet made up of standard laboratory chow supplemented with 0.5% of a mixture of brominated sunflower‐olive oil (BVO) developed a significant increase in the triacylglycerol content of the heart, liver and soleus muscle compared to controls. In addition, BVO‐treated rats had a decrease in plasma levels of triacylglycerol and total and HDL cholesterol. Plasma fatty acid levels and plasma post‐heparin lipolytic activities, such as H‐TGL, LPL, T‐TGL and MGH were similar to those of control animals fed the standard chow alone.Heart PDHa (active portion of pyruvate dehydrogenase) was dramatically decreased in the BVO‐fed rats. A faster rate of spontaneous lipolysis was recorded in the isolated perfused preparation of hearts from the experimental animals. The addition of 10−7 M of glucagon to the perfusate, however, revealed a lipolytic effect comparable to the one observed in the control rats. In summary, our findings of normal fatty acids and low triacylglycerol plasma levels associated with normal activities of the various PHLA (post‐heparin lipolytic activity) enzymes suggest that accumulation of triacylglycerol in heart muscle may not be explained essentially in terms of an elevated uptake and/or increased delivery of plasma fatty acids or plasma triacylglycerol. A decreased in situ catabolism of tissue triacylglycerol also appears unlikely because the spontaneous as well as the glucagon induced lipolysis in the heart both were found to be unimpaired.Our results suggest that the mechanisms involved in the toxicologic effects of a BVO diet on heart lipid metabolism could be exerted mainly at the level of triacylglycerol biosynthesis rather than a derangement in some known step of their catabolic pathway. Additional studies are necessary to clarify this matter.
Fatty acids of sphingomyelin from amniotic fluid of normal and diabetic pregnancies
Authors: Kokatnur Mohan , Brooks Vicki , Plauche Warren C. 
Published: November 2006

AbstractAmniotic fluid collected from 14 normal and 11 diabetic patients was analyzed for phospholipids, and separated sphingomyelin and lecithin fractions were further studied for their fatty acid composition by gas liquid chromatography. Notable differences in percent fatty acid composition of sphingomyelin were observed for palmitic (16∶0; diabetic < normal), oleic (18∶1; diabetic > normal), behenic (22∶0; diabetic < normal) and arachidic acid (20∶0; absent in diabetics) in the specimens studied. Notable differences were not observed in fatty acids from lecithin fraction. Fatty acid composition of sphingomyelin from amniotic fluid is similar to fatty acid distribution in sphingomyelin from serum and erythrocyte and suggests maternal origin of the lipid.
Inhibition of C28 and C29 phytosterol metabolism by N, N‐dimethyldodecanamine in the nematodecaenorhabditis elegans
Authors: Lozano Ruben , Lusby William R. , Chitwood David J. , Thompson Malcolm J. , Svoboda James A. 
Published: November 2006

AbstractEffects on the metabolism of campesterol and stigmasterol inCaenorhabditis elegans were investigated using N,N‐dimethyldodecanamine, a known inhibitor of growth, reproduction and the Δ24‐sterol reductase of this nematode. 7‐Dehydrocholesterol was the predominant sterol (51%) ofC. elegans grown in stigmasterol‐supplemented media, whereas addition of 25 ppm amine resulted in a large decrease in the relative percentage of 7‐dehydrocholesterol (23%) and the accumulation of a substantial proportion (33%) of Δ24‐sterols (e.g., cholesta‐5,7,24‐trienol) and Δ22,24‐sterols (e.g., cholesta‐5,7,22, 24‐tetraenol) but yielded no Δ22‐sterols. Dealkylation of stigmasterol byC. elegans proceeded in the presence of the Δ22‐bond; reduction of the Δ22‐bond occurred prior to Δ24‐reduction. Addition of 25 ppm amine to campesterol‐supplemented media altered the sterol composition ofC. elegans by increasing the percentage of unmetabolized dietary campesterol from 39 to 60%, decreasing the percentage of 7‐dehydrocholesterol from 26 to 12%, and causing the accumulation of several Δ24‐sterols (6%).C. elegans also was shown to be capable of dealkylating a Δ24(28)‐sterol as it converted 24‐methyl‐enecholesterol to mostly 7‐dehydrocholesterol. The proposed role of 24‐methylenecholesterol as an intermediate between campesterol and 7‐dehydrocholesterol was supported by the results.
High performance liquid chromatographic separation of stereoisomeric bile acids as their UV‐sensitive esters
Authors: Iida Takashi , Ohnuki Yasuo , Chang Frederic C. , Goto Junichi , Nambara Toshio 
Published: November 2006

AbstractHigh performance liquid chromatographic separation of a series of mono‐, di‐ and trihydroxylated 5β‐cholanic acids which differ only in position and configuration of hydroxyl groups at positions C‐3, C‐7 and/or C‐12, is reported. The C‐24 free acids were derivatized to four different classes of UV‐sensitive esters, i.e.,p‐bromophenacyl (BP),m‐methoxyphenacyl (MP), 4‐nitrophthalimidemethyl (NPM) and 9‐anthrylmethyl (AM) esters, and chromatographed on two, variants of C18 reversed‐phase columns (Nova‐Pak C18 and Zorbax ODS) with methanol‐water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs were influenced by both the structure of the C‐24 ester groups and the nature of the columns used. Excellent chromatographic properties were found for those derivatives, particularly for the NPM esters.
Lipid composition of different areas of murine brain: Effects of lipid extraction procedures
Authors: Katyal S. L. , Barilaro Linda , Hanin Israel 
Published: November 2006

AbstractThe effects of various chemical extraction procedures on the determination of lipid composition of rat and mouse brain have been investigated. Tissue extractions with formic acid/acetone or perchloric acid both resulted in significant losses of total phospholipids and cholesterol. Perchloric acid extraction also degraded, almost quantitatively, ethanolamine plasmalogens to lysophosphatidylethanolamine. Our findings have thus demonstrated that conventional procedures used for extraction of brain tissue for analysis of choline and acetylcholine content cannot also be used for concurrent/simultaneous extraction of phospholipids and cholesterol from the same tissue.
Dietary fats containing concentrates ofcis ortrans octadecenoates and the patterns of polyunsaturated fatty acids of liver phosphatidylcholine and phosphatidylethanolamine
Authors: Lawson Larry D. , Hill Eldon G. , Holman Ralph T. 
Published: November 2006

AbstractThe effects of the mixedcis‐ 18∶1 isomers and mixedtrans‐18∶1 isomers present in partially hydrogenated soybean oil (PHSO) upon the patterns of polyunsaturated fatty acids (PUFA) in liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were studied in rats fed concentrates ofcis‐ 18∶1 ortrans‐ 18∶1 isomers isolated as triacylglycerides from PHSO. Thecis‐ 18∶1 andtrans‐ 18∶1 concentrates were fed at levels equal to those present in PHSO fed at 17.9% of the diet. All diets contained the required amounts of both linoleic and linolenic acids. Thetrans‐ 18∶1 concentrate was found to suppress the levels of 20∶4ω6 and 20∶3ω9, and to increase the levels of 18∶2ω6 and 20∶5ω3 in PC and PE. Thecis‐ 18∶1 concentrate suppressed 20∶4ω6 in PC, 20∶5ω3 in PC and PE, and 18∶2ω6 was more effective than thetrans concentrate in suppressing 22∶6ω3. Thetrans‐ 18∶1 concentrate was more effective in suppressing 20∶4ω6. Thetrans‐18∶ isomers appear to modify PUFA metabolism by inhibition of PUFA synthesis, whereas thecis‐ 18∶1isomers appear to compete with 2‐position fatty acyl transfer and to inhibit ω3 PUFA acylation.
The effect of a non‐absorbable fat on the turnover of plasma cholesterol in the rat
Authors: Mattson Fred H. , Jandacek Ronald J. 
Published: November 2006

AbstractRats were injected with [4‐14C]‐cholesterol and then fed diets that contained sucrose polyester (SPE) at levels of 0 and 8% of the diet.14C was measured in neutral and acidic steroid fractions of the feces collected during days 35–39 post i.v. injection. Periodic blood samples were used to measure the specific activity of the plasma cholesterol. The plasma data were consistent with a two‐pool model for the decay of the plasma specific activity. The slow component of the decay curve decreased more rapidly in animals that received SPE. The half‐life corresponding to this component was approximately 20% shorter in the SPE‐fed animals compared to the control group. The mass of cholesterol calculated for the first pool was similar for all groups of animals. The14C found in the feces was consistent with the more rapid removal of cholesterol from the body in the SPE‐fed animals. The mass of excreted steroid was equal to the calculated rate of cholesterol production in each group of animals.
Unsaturated fatty acids compositional changes and desaturation during the embryonic development of the chicken (Gallus domesticus)
Authors: Noble R. C. , Shand J. H. 
Published: November 2006

AbstractAn investigation has been made to correlate the activities of the Δ9‐ and Δ6‐long chain fatty acid desaturation systems with the increased levels of oleic and arachidonic acids in the liver relative to the yolk sac membrane of the chick embryo during the last week of development. The membrane exhibited high levels of both stearic and linoleic acid desaturation in the early stages of yolk lipid mobilization, the activities of both enzyme systems decreasing with the approach of hatching. Stearic acid desaturation in the liver also decreased with the approach of hatching, but linoleic acid desaturation increased. The observed levels of desaturation in the yolk sac membrane are capable of making a conbryonic liver, the requirement for which does not appear to be satisfied by the yolk lipids. With the approach of hatching and the functional regression of the yolk sac membrane, the role is taken over by the embryonic tissues.
Preparation of hydroperoxy and hydroxy derivatives of rat liver phosphatidylcholine and phosphatidylethanolamine
Authors: Terao J. , Asano I. , Matsushita S. 
Published: November 2006

AbstractA convenient method for the preparation of hydroperoxy and hydroxy derivatives of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is described. PC and PE obtained from rat liver were oxidized with singlet oxygen by using methylene blue as the photosensitizer, and their hydroperoxides were isolated with the aid of reverse phase liquid chromatography. The hydroxy derivatives were obtained by reducing the hydroperoxides with sodium borohydride. The results of gas chromatography mass spectrometry revealed that hydroxy fatty acid components of the hydroxy derivatives were derived from isomeric hydroperoxides of oleic acid, linoleic acid, arachidonic acid and docosahexanoic acid. Normal phase high performance liquid chromatography did not separate the hydroperoxy and hydroxy derivatives from the respective unoxidized phospholipids, although unoxidized PC and PE were separated from each other. However, the hydroperoxy and hydroxy derivatives could be distinguished from unoxidized phospholipid species on reversed phase thin layer chromatography.
Stimulation by lipoxygenase products of superoxide anion production in FMLP‐treated neutrophils
Authors: Beckman Jeffrey K. , Gay James C. , Brash Alan R. , Lukens John N. , Oates John A. 
Published: November 2006

AbstractOur recent observation that leukotriene B4 (10−9M) is a potent enhancer of FMLP‐initiated neutrophil superoxide anion formation prompted an evaluation of the ability of other lipoxygenase products and related compounds to modulate this response. The results indicate that FMLP‐evoked O2− may be enhanced by 10−8–10−7 M levels of a number of lipids, in addition to LTB4, including 5‐HPETE, 5‐HETE, 5,15‐DiHPETE and by higher levels of other 15‐series lipoxygenase products and arachidonic acid. It is of interest that the relative potency of these agents in potentiating the superoxide response to FMLP approximately parallels their reported ability to induce chemotactic activity in leukocytes.
Oral polyunsaturated phosphatidylcholine reduces platelet lipid and cholesterol contents in healthy volunteers
Authors: Galli C. , Tremoli E. , Giani E. , Maderna P. , Gianfranceschi G. , Sirtori C. R. 
Published: November 2006

AbstractThe effects of orally administered polyunsaturated phosphatidylcholine (PPC) on plasma lipids, lipoproteins and platelet function and composition were studied in seven healthy male volunteers. PPC (Nattermann & Cie, GmbH, Cologne, Federal Republic of Germany), 10 g/day, was given for a 6‐week period after a 4‐week wash out; laboratory tests were repeated after a further 4‐week period after the end of treatment. PPC did not appear, during treatment, to modify the levels of plasma total cholesterol and triglycerides. High density lipoprotein (HDL) cholesterol levels were, however, increased after six weeks of PPC. The most dramatic changes occurred in platelet membrane composition: the total lipid/total protein and the cholesterol/protein ratios were reduced significantly, whereas increases of the phospholipid/total lipid ratio and of the linoleic acid membrane content were observed. Platelet function tests, both in whole blood and in platelet rich plasma, were not modified. Similarly, the thromboxane B2 formation after standard stimuli and the sensitivity to exogenous prostaglandin I2 also were unchanged. During the final wash out period following treatment, a reduction of plasma total and low density lipoprotein (LDL) cholesterol levels also was recorded. PPC appears to be capable of modulating lipid exchanges between cell membranes and the plasma compartment.
Foraging strategies involved in habitat use of shorebirds at the intertidal area of Chongming Dongtan, China
Authors: Jing Kai , Ma Zhijun , Li Bo , Li Jinhua , Chen Jiakuan 
Published: November 2006

AbstractDense flocks of migratory shorebirds from diverse species often concentrate in the intertidal areas for stopover. Trophic structure, food partition, prey availability and selectivity, predation risk, and abiotic factors are often used to explain the differences in habitat use of coexisting shorebirds. We sampled the macrobenthos and surveyed the distribution of shorebird populations to study the effects of foraging strategies on the habitat use of shorebirds at Chongming Dongtan, an important stopover site for shorebirds on the East Asian–Australasian Flyway. Results show that the relative abundance of epifaunal macrobenthos in salt marshes was much higher than that in the bare flats, whereas the relative abundance of infaunal macrobenthos in salt marshes was much lower than that in bare flats. The relative abundance of two life forms of macrobenthos was similar in the transitional zones between the salt marshes and the bare flats. Shorebirds with different foraging strategies exhibited different habitat uses. Pause‐travel shorebirds mainly utilized the salt‐marsh fringes, while tactile continuous shorebirds relied heavily on the bare flats. There was no significant difference in habitat use for visual continuous shorebirds. The density of tactile continuous shorebirds was positively correlated with bivalve density, and that of visual continuous shorebirds positively with crustacean density. Meanwhile, the relative abundance of pause‐travel foraging shorebirds was positively correlated with the relative abundance of epifaunal, but negatively with infaunal macrobenthos. In contrast, the relative abundance of tactile foraging shorebirds had a positive correlation with infaunal but a negative one with epifaunal life form. Therefore, foraging strategies may play important roles in shorebirds’ habitat use in intertidal areas.
Protein‐precipitating capacity of crude condensed tannins of canola and rapeseed hulls
Authors: Naczk M. , Amarowicz R. , Zadernowski R. , Shahidi F. 
Published: November 2006

AbstractThe protein‐precipitating potentials (PPP) of soluble condensed tannins (SCT) were determined in hulls from several samples of canola and rapeseed varieties. The PPP were expressed as slopes of lines (titration curves) reflecting the amount of SCT‐protein precipitated vs. the amount of SCT added to the reaction mixture. The slopes (Sp) of titration curves obtained using the protein‐precipitation assay ranged from 2.96 to 10.91 (absorbance units at 510 nm per mg SCT), and those of titration curves, obtained using the dye‐labeled bovine serum albumin (BSA) assay (Sd), ranged from 28.1 to 267 (% precipitated BSA per mg SCT). For both assays, a statistically significant (P≤0.001) semilogarithmic linear correlation existed between the slopes and the SCT contents in the canola and rapeseed hulls. Higher amounts of SCT‐protein complexes were precipitated at 40°C than at room temperature. Determination of titration curves under standardized conditions (type and concentration of protein, pH and temperature) afforded meaningful differences in the slopes among the range of SCT extracts from canola and rapeseed hulls used in this study.
Adaptation of the AOCS official method for measuring hydroperoxides from small‐scale oil samples
Authors: Crowe Tammy D. , White Pamela J. 
Published: November 2006

AbstractAn adaptation of the American Oil Chemists' Society Official Method Cd 8–53 for determining peroxides in fats and oils using a 0.5‐g sample is described. Comparisons of the Official Method and the small‐scale method were performed by analyzing soybean oil samples spiked with t‐butyl hydroperoxide and autoxidized soybean oil samples. A linear relationship between the Official Method and the small‐scale method was obtained with an R2 of 0.998. The small‐scale method is sensitive, precise, and suitable for small sample sizes and uses only about 10% of the chemicals necessary for the Official Method.