bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of [U‐13C]eicosapentaenoic acid in rat liver lipids using13C nuclear magnetic resonance spectroscopy
Authors: Cunnane S. C. , McDonagh R. J. , Narayan S. , Kyle D. J. 
Published: November 2006

AbstractFatty acid carbons are well‐resolved in13C nuclear magnetic resonance (NMR) spectra of lipid extracts, but application of this methodology to the metabolism of13C‐labelled fatty acids has not yet been reported. In the present study,13C NMR was used to monitor the presence of 98% [U‐13C]eicosapentaenoic acid (EPA) in liver and carcass lipids 24 h after it had been injected into the stomach of a rat. Natural abundance13C NMR spectra of liver total fatty acid extracts were obtained from four control rats for comparison. At 24 h post‐injection, quantitative high resolution13C NMR showed13C enrichment in liver fatty acid extracts was present mainly at olefinic and at the n−1 to n−4 carbons, but13C signal intensities for C−1 to C−4 of [U‐13C]EPA were markedly reduced or absent. Small13C resonances, possibly indicative of some13C incorporation into docosahexaenoic acid and saturated or monounsaturated fatty acids, were present in spectra of liver fatty acids. Liver and carcass fatty acid composition was similar in both the controls and the EPA‐injected rat, suggesting little accumulation of the injected [U‐13C]EPA after 24 h. We conclude that the carbon‐specific data provided by13C NMR of lipid extracts may be useful in monitoring the fate of individual carbons during tracer studies using13C‐labelled fatty acids.
Positional distribution on n−3 fatty acids in triacylglycerols from rat adipose tissue during fish oil feeding
Authors: Leray Claude , Raclot Thierry , Groscolas René 
Published: November 2006

AbstractThe present study was designed to investigate the metabolism of the n−3 olyunsaturated fatty acids (PUFA) in adipose tissue and its dependence upon dietary factors. Changes in the positional distribution of the fatty acids in triacylglycerols from retroperitoneal adipose tissue were studied as a function of time on rats fed for 4 wk a diet enriched with fish oil. The stereospecific analysis of triacylglycerols was based on random formation ofrac‐1,2‐diacylglycerols by Grignard degradation. This was followed by synthesis ofrac‐phosphatidic acids and treatment with phospholipase A2. In the triacylglycerols of the fish oil diet, 57% of the total n−3 fatty acids were in position 3,i.e., two‐thirds of 22∶5n−3 and 22∶5n−3 were esterified insn‐3 position, whereas 22∶6n−3 was equally distributed in positions 2 and 3. After 4 wk of feeding fish oil, the fatty acid composition of adipose tissue triacylglycerols reached a steady state. Half of the n−3 fatty acids were found in position 3, namely 75% of 22∶5n−3, 50% of 20∶5n−3 and 18∶4n−3 and 45% of 22∶6n−3, the latter being equally distributed in positions 2 and 3. This pattern of distribution resembled that found in triacylglycerols of the fish oil diet, except for a higher proportion of 20∶5n−3 in adipose tissue in position 1 at the expense of position 3. Throughout the 4‐wk period of fish oil feeding, the distribution pattern of minor n−3 fatty acids (18∶4n−3 and 22∶5n−3) in adipose tissue triacylglycerols remained unchanged. On the other hand, at the onset of fish oil feeding, 20∶5n−3 and 22∶6n−3 became concentrated in position 3, but thereafter 20∶5n−3 was progressively incorporated into position 1 and 22∶6n−3 into position 2. We thus conclude that n−3 fatty acids are differentially esterified in triacylglycerols of white adipose tissue. Despite the complex sequence of hydrolysis and acylation steps involved, the positional distribution of n−3 fatty acids was found to be similar in both the fish oil diet and the stored fat, in contrast to what was observed for nonessential fatty acids.
Effect of Δ9‐tetrahydrocannabinol and merthiolate on acyltransferase activities in guinea pig liver microsomesand merthiolate on acyltransferase activities in guinea pig liver microsomes
Authors: Badiani Ketan , Lu Xiaoli , Arthur Gilbert 
Published: November 2006

AbstractΔ9‐tetrahydrocannabinol (THC) and merthiolate have been utilized as lysophospholipid acyltransferase inhibitors in metabolic studies. However, their effects on acyltransferases other than lysophosphatidylcholine:acyl‐CoA acyltransferase (LPCAT) are not known. We have therefore investigated the effectiveness of THC and merthiolate in inhibiting the acylation of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine, lysophosphatidylinositol (LPI) and lysophosphatidic acid (LPA) in guinea pig liver microsomes using oleoyl‐CoA and arachidonoyl‐CoA as acyl donors. THC inhibited LPCAT and lysophosphatidylethanolamine: acyl‐CoA acyltransferase (LPEAT) by 40–50%, but had no effect or only slightly increased the activities of the other acyltransferases when assayed with oleoyl‐CoA as the acyl donor. The results obtained with arachidonoyl‐CoA were similar to those with oleoyl‐CoA, with the exception of a 40% inhibition of lysophosphatidylserine:acyl‐CoA acyltransferase (LPSAT) at concentrations of 50 μM or higher. At similar concentrations, merthiolate was more effective than THC in inhibiting the acyltransferases examined. Selective effects on the acyltransferases were observed at low concentrations of merthiolate (20 μM or less). Thus, LPCAT was most susceptible, followed by LPI acyltransferases, LPSAT, LPEAT and lysophosphatidic acid:acyl‐CoA acyltransferases (LPAAT). The presence of LPA did not affect the inhibition of LPCAT by merthiolate. Thus the resilience of LPAAT to merthiolate inhibition was not due to chelation of the compound by the acidic lysolipid. Thiol reagents includingN‐ethylmaleiamide, 5,5′‐dithio‐bis‐nitrobenzoic acid, iodoacetate, β‐mercaptoethanol and dithiothreitol had little or no effect on the acyltransferases relative to equimolar concentrations of merthiolate. The above results indicate that merthiolate is a much more effective inhibitor of lysophospholipid:acyl‐CoA acyltransferases than is THC, and that the selectivity exhibited by merthiolate may be due to direct and specific interaction with the acyltransferases.
Cholesterol gallstone induction in hamsters reflects strain differences in plasma lipoproteins and bile acid profiles
Authors: Trautwein Eike A. , Liang Jinsheng , Hayes K. C. 
Published: November 2006

AbstractBecause different strains of hamsters vary in their susceptibility to gallstones, the relationship between plasma lipoproteins, hepatic cholesterol, bile lipids and bile acid profile was examined during gallstone induction in strains of male Syrian hamsters from Charles River Lakeview (CHR), Biobreeder F1B (BIO) and Harlan Sprague‐Dawley (HAR). Gallstones were induced by feeding a purified diet containing 0.4 or 0.8% cholesterol for 5 wk. Basal plasma total cholesterol was similar, but the hypercholesterolemia induced by dietary challenge was significantly lower in CHR than in HAR and BIO hamsters. Cholesterol‐fed CHR hamsters transported cholesterol mainly in HDL (47%), whereas VLDL‐C+IDL‐C predominated in BIO and HAR hamsters, and their HDL transported only 28 and 38%, respectively. HAR hamsters accumulated the most hepatic cholesterol, revealed the highest cholate/cheno ratio, the lowest glycine/taurine ratio and hydrophobicity index. HAR also developed the fewest cholesterol gallstones (23%), while 64% of CHR and 58% of BIO hamsters had cholesterol gallstones and 34% of BIO hamsters developed pigment stones. Doubling dietary cholesterol from 0.4 to 0.8% doubled the incidence of cholesterol gallstones but exerted minimal impact on other parameters compared to strain differences. Thus, different strains of hamsters vary considerably with respect to biliary cholesterol, bile acid profile and formation of cholesterol gallstones associated with differences in plasma lipoprotein profiles.
Hydrolysis of fish oils containing polymers of triacylglycerols by pancreatic lipasein vitro
Authors: Henderson R. James , Burkow Ivan C. , Millar Rose Mary 
Published: November 2006

AbstractFish oils containing different levels of polymers of triacylglycerols formed during autoxidation were incubated with pancreatic lipase to establish whether these polymers are substrates for lipase hydrolysis. With oils containing low amounts (less than 4%) of triacylglycerol polymers as substrates, both triacylglycerols and polymers of triacylglycerols were almost completely hydrolyzed, and fatty acid monomers and monoacylglycerols were the major lipid products. Under the same incubation conditions, some triacylglycerols remained intact when highly oxidized oils containing 20 or 30% triacylglycerol polymers were the substrate. The fatty acid composition of these residual triacylglycerols was almost identical to that of triacylglycerols present at the start of the assay. When fish oil containing 30% triacylglycerol polymers was incubated with the lipase, the component triacylglycerols and polymers of triacylglycerols were hydrolyzed at similar rates, and fatty acid dimers were detected as a product. It is concluded that the high molecular weight polymers of triacylglycerols present in oxidized fish oils can be hydrolyzed by pancreatic lipasein vitro.
Stearidonic acid, an inhibitor of the 5‐lipoxygenase pathway. A comparison with timnodonic and dihomogammalinolenic acid
Authors: Guichardant Michel , Traitler Helmut , Spielmann Danièle , Sprecher Howard , Finot Paul‐André 
Published: November 2006

AbstractLeukotrienes have been shown to play an important role as mediators in various disease processes, including asthma and inflammation; thus, their synthesis is tightly regulated. The major precursor of leukotrienes is arachidonic acid (20∶4n−6). Fatty acids which are structurally similar to 20∶4n−6, such as eicosatrienoic acid (20∶3n−6; dihomogammalinolenic acid) and eicosapentaenoic acid (20∶5n−3; timnodonic acid) have been found to inhibit leukotriene biosynthesis. Because of the structural similarity of octadecatetraenoic acid (18∶4n−3; stearidonic acid) with 20∶4n−6, the present study was undertaken to determine whether stearidonic acid also exerts an inhibitory effect on the 5‐lipoxygenase pathway. Human leukocytes were incubated with 18∶4n−3 (20 μM or 10 μM), 20∶5n−3 (20 μM) or 20∶3n−6 (20 μM) and subsequently stimulated with 1 μM ionophore A23187 and 20∶4n−6 (20 μM or 10 μM). The 5‐lipoxygenase products were then measured by high‐performance liquid chromatography. Leukotriene synthesis was reduced by 50% with 20 μM 18∶4n−3 and by 35% with 10 μM 18∶4n−3. Formation of 5S,12S‐di‐hydroxy‐eicosatetraenoic acid and of 5‐hydroxy‐eicosatetraenoic acid was decreased by 25% with 20 μM 18∶4n−3 and by 3% with 10 μM 18∶4n−3. The inhibition observed with 20 μM 18∶4n−3 appeared to be of the same order as that observed with 20 μM 20∶5n−3; the inhibition observed with 18∶4n−3 was shown to be dosedependent. The inhibition produced by 20 μM 20∶3n−6 was greater than that observed with either 20 μM 18∶4n−3 or with 20 μM 20∶5n−3. The results suggest that stearidonic acid, which is found, for example, in blackcurrant seed oil (which also contains the 20∶3n−6 precursor), may play a role in suppressing inflammation.
O‐alkyl diolO‐,S‐ andSe‐phosphoroamidates of DL‐α‐tocopherol and their dimethylaminoalkyl derivatives as diester and triester models of phospholipids
Authors: Stamatov Stephan D. , Gronowitz Salo 
Published: November 2006

AbstractHexamethyltriamide 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 1‐hexadecyloxyethyl‐2‐O‐, 1‐hexadecyloxypropyl‐3‐O‐, and 1‐hexadecyloxybutyl‐4‐O‐(DL‐α‐tocopheryl‐6‐O)‐(N,N‐dimethylamido)selenophosphate,‐thiophosphate and‐phosphate derivatives, and some of their 2‐dimethyl‐aminoethyl‐1‐O‐, and 3‐dimethylaminopropyl‐1‐O‐triester analogues in a “one‐pot procedure” in overall yields of 69–87%. Activation of the reaction with an equimolar mixture of imidazole and carbon disulfide at the triester formation step permits selective phosphorylation at room temperature. The compounds synthesized represent new diester and triester models containing alkyl ether diolphospholipid structures.
Use of acetyl chloride/methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids
Authors: Hallaq Youssef , Becker Thomas C. , Manno Catherine S. , Laposata Michael 
Published: November 2006

AbstractThe albumin‐bound nonesterified fatty acid pool in plasma, which represents a very small percentage of total plasma fatty acids, has previously been quantitated by a variety of methods. In the present study we determined that the nonesterified fatty acid concentrations in the plasma, quantitated by a popular method using acetyl chloride and methanol which is reported to be specific for methylation of nonesterified fatty acids in the presence of esterified fatty acids (i.e., without prior isolation of the plasma non‐esterified fatty acids), were significantly overestimated due to cleavage and methylation of esterified fatty acids. Quantitation of the contaminating fatty acid from the esterified pool demonstrated that the amount of fatty acid cleaved from the esterified pool was enough to exceed the entire mass of nonesterified fatty acids. As an established method for comparison, we isolated nonesterified fatty acids from the plasma by thin‐layer chromatography prior to methylation, using a number of simple precautions to limit oxidation. By performing all thin‐layer chromatography steps in an atmosphere of nitrogen and by including fatty acid standards in the plasma with 0,1, 2 or 4 double bounds, we were able to accurately and reproducibly determine the concentration of nonesterified fatty acids in the plasma, including arachidonate. We demonstrated that no oxidation occurred in the thin‐layer chromatographic isolation of homonesterified fatty acids and that the coefficients of variation for repeat measurements of the same sample were <11% using our reference method. Our data indicate that the use of acetyl chloride and methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids.
Profiling of arachidonic acid metabolites in rabbit platelets by radio gas chromatography
Authors: Akira Kazuki , Nakamura Tatsuji , Shinohara Yoshihiko , Baba Shigeo 
Published: November 2006

AbstractA method for profiling arachidonic acid metabolites by radio gas chromatography (GC) is described. The incubation mixture of rabbit platelets with [14C]arachidonic acid was purified on a Sep‐Pak C18 cartridge and derivatized with diazomethane,O‐methylhydroxylamine and dimethylisopropylsilylimidazole. The recovery of total14C‐radioactivity was 93.1±7.2%. Loss of radioactivity during derivatization was negligible. Baseline separations for [14C]arachidonic acid and its metabolites were obtained in a single run within 45 min by GC using a synchronized accumulating radioisotope detector (GC/SARD). The recovery of radioactivity from the GC column was virtually 100%. The chemical structures of the metabolites were confirmed by GC/mass spectrometry; peaks of arachidonic acid metabolites were assigned by comparison of the methylene unit values with those of radioactive peaks in GC/SARD analyses. The intra‐assay coefficients of variation in GC/SARD analyses were less than 10%. The method was used to map the profile of arachidonic acid metabolites formed by rabbit platelets in the presence of indomethacin, baicalein or glutathione.
Effect of nonionic detergents on lipoxygenase catalysis
Authors: Schilstra Maria J. , Veldink Gerrit A. , Vliegenthart Johannes F. G. 
Published: November 2006

AbstractIn many studies on lipoxygenase catalysis, nonionic detergents are used to obtain an optically transparent solution of the fatty acid substrate. In order to resolve some controversies that exist with regard to the interpretation of kinetic data obtained with solutions containing nonionic detergents, a systematic investigation was undertaken into the effects of Lubrol, Tween‐20 and Triton X‐100 (0–0.8 g/L) on the kinetics of linoleate (2.5–110 μM) dioxygenation, catalyzed by lipoxygenase‐1 or lipoxygenase‐2 from soybean, at pH 9 or 10, at 25°C. Under most conditions, it was found that the detergents slowed down the reaction. However, at high linoleate concentrations, where substrate inhibition of lipoxygenase is significant, small amounts of detergent increased the dioxygenation rate. In a quantitative analysis of the results, a kinetic model in which the incorporation of linoleate in the detergent micelles is formulated as a simple reversible equilibrium, and in which both lipoxygenase‐1 and‐2 interact with free linoleate, but not with linoleate incorporated in the micelles, appeared to be sufficient to predict experimental results over a wide range of experimental conditions. According to this model, the changes in the dioxygenation kinetics caused by the presence of nonionic detergents are similar (but not equal) to those caused by competitive inhibitors. The conclusions that monomeric, nonmicellar linoleate is the preferred substrate for lipoxygenase and that the observed inhibition and stimulation are solely due to changes in the effective linoleate concentration strongly corroborate the earlier observations by Galpin and Allen [Biochim. Biophys. Acta 488 (1977), 392–401].
Effect of n−3 fatty acid‐rich fish oil supplementation on the oxidation of low density lipoproteins
Authors: Frankel E. N. , Parks E. J. , Xu R. , Schneeman B. O. , Davis P. A. , German J. B. 
Published: November 2006

AbstractThis study was aimed at determining the effect of fish oil supplementation on copper‐catalyzed oxidation of low density lipoproteins (LDL) from nine hypertriglyceridemic human subjects. A rapid headspace gas chromatographic method was used to measure the volatile oxidation products from LDL. Propanal and hexanal were the major volatile products formed in the oxidation of n−3 and n−6 polyunsaturated fatty acids (PUFA), respectively. Fish oil supplementation resulted in a significant increase in propanal formation from 3.7 to 13.4 nmol/mL LDL (P<0.01); it also resulted in small decreases in pentanal formation from 14.7 to 11.4 nmol/mL LDL and in hexanal formation from 138 to 108 nmol/mL LDL (P<0.05). The changes in peroxidation products paralleled the changes in LDL composition, which showed a significant increase in n−3 PUFA from 3.2 to 14.6% (P<0.01) and a decrease in n−6 PUFA from 43.7 to 35.0% (P<0.05). Propanal formation was highly and significantly correlated with n−3 PUFA content (r=0.950,P<0.001). Since total volatiles remained unchanged, this indicated that the two groups of LDL samples did not differ in overall oxidative susceptibility. Although fish oil intake did not alter the oxidative susceptibility of LDL, the chemically modified LDL particles generated a distinct pattern of volatile oxidation products that reflected changes in their fatty acid composition.
Superoxide production by macrophages stimulatedin vivo with synthetic ether lipids
Authors: Schreiber Barbara M. , Layne Matthew D. , Modest Edward J. 
Published: November 2006

AbstractThe anticancer activity of synthetic ether lipids may depend in part upon their ability to activate cells of the monocyte/macrophage lineage. In the present study, we have sought to determine whether 1‐O‐octadecyl‐2‐O‐methyl‐rac‐glycero‐3‐phosphocholine (ET‐18‐OMe) and related ether lipids enhance superoxide production by mouse peritoneal macrophages. Ether lipids were administered intraperitoneally to C57BL/6 mice 4 d after injection with thioglycollate broth. Elicited peritoneal macrophages were harvested and purified one day later, and superoxide production was detected by measuring the superoxide dismutase inhibitable reduction of cytochrome c. Low levels of superoxide were secreted by macrophages in the absence of phorbol 12‐myristate 13‐acetate (PMA). When PMA was addedin vitro to macrophages from ET‐18‐OMe‐treated mice, these cells secreted 194.2 nmol superoxide/mg protein in comparison to 53.5 nmol superoxide/mg protein for PMA‐treated control cells. Thein vitro treatment of the macrophages with ET‐18‐OMe was not effective in stimulating superoxide secretion. Macrophages harvested from mice treated with a series of ether lipids (with and without phosphorus) were examined, and superoxide secretion was found to vary with structure. AM‐18‐OEt and CP‐7 were the most effective compounds, secreting 8.6 and 11.9 times more superoxide, respectively, than PMA‐stimulated control cells. Moreover, direct cytotoxicity of the compounds for HL60 human promyelocytic leukemic cells did not necessarily correlate with the ability of each drug to increase macrophage superoxide production.
Modification of lysine amino groups by the lipid peroxidation product 4,5(E)‐Epoxy‐2(E)‐hepteal
Authors: Zamora Rosario , Hidalgo Francisco J. 
Published: November 2006

AbstractThe reaction between 4,5(E)‐epoxy‐2(E)‐heptenal (EH) andl‐lysine was studied to characterize some of the compounds that may be produced when proteins react with peroxidizing lipids. A mixture of EH and lysine was incubated overnight at room temperature and then fractionated by high‐performance liquid chromatography (HPLC). Fractions were freeze‐dried and characterized by1H and13C nuclear magnetic resonance (NMR) and mass spectrometry. Four major pyrrole derivatives were obtained, namely 1‐(5′‐amino‐1′‐carboxypentyl)‐pyrrole (3), 1‐(5′‐amino‐1′‐carboxypentyl)‐2‐(1″‐hydroxypropyl)pyrrole (diastereomers 5 and 8), 1‐(5′‐amino‐5′‐carboxypentyl)pyrrole (7), and 1‐(5′‐amino‐5′‐carboxypentyl)‐2‐(1″‐hydroxypropyl)pyrrole (9). In addition, several lysine complexes were detected. A polymer (1b) that was responsible for the color and the fluorescence produced in the reaction was isolated by gel filtration chromatography from a fraction obtained by HPLC. Formation of pairs of analogs (5 and 3, 9 and 7) with and without a substituent in position 2 of the pyrrole ring suggested that the compounds were produced by the same mechanism, with the formation of the 2‐unsubstituted pyrroles corresponding to the loss of the 2‐substituent as propanal; propanal was detected by headspace capillary gas chromatography. A reaction mechanism is proposed based on the NMR data obtained when the reaction was monitored in real time in an NMR tube. The results suggest that pyrrolic amino acids 7 and 9 may be present in proteins that have been damaged by peroxidizing lipids.