bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monoenoic fatty acids in human brain lipids: Isomer identification and distribution
Authors: Johnson D. W. , Beckman K. , Fellenberg A. J. , Robinson B. S. , Poulos A. 
Published: November 2006

AbstractThe carbon chain length distribution and the double bond positional isomer composition of the monoenoic fatty acids of the lipids of total human brain tissue have been determined using gas chromatography and gas chromatography/mass spectrometry of the fatty acid methyl and picolinyl esters. The even chain length monoenoic C16 to C28 fatty acids contain predominantly two positional isomer series, the n−7 and n−9cis homologues, whose relative proportion varies significantly with chain length. The odd chain length long‐chain fatty acids consist of n−8 and n−10 isomers, whereas the odd chain length very long‐chain (more than 22 carbon) fatty acids are n−7 and n−9 isomers.
Effects of polyphenolic natural products on the lipid profiles of rats fed high fat diets
Authors: Yugarani T. , Tan B. K. H. , Teh M. , Das N. P. 
Published: November 2006

AbstractMale Wistar rats were fed a high fat diet (HFD) containing 2.5% cholesterol and 16% lard supplemented with polyphenolic natural products namely quercetin, morin or tannic acid (100 mg/rat/day) for 4, 7 and 10 wk. Rats fed HFD without the supplements served as control. The effects of these compounds on blood lipid profiles, enzymes, liver fat and aorta of the rat were studied. In rats fed HFD containing tannic acid, plasma total cholesterol (TC), low density lipoprotein cholesterol (LDLC) and triglyceride (TG) were reduced by 33.3%, 29.6% and 65.1%, respectively, at week 10. High density lipoprotein cholesterol (HDLC) concentration was not altered. Fat deposition was also decreased in the liver of these rats. Morin significantly reduced plasma TG (65.1%) and liver fat only at week 7 while at week 10 it reduced plasma TC and LDLC by 30.9% and 29.3% respectively. The plasma HDLC concentration was increased by 47.3% at week 4 but no effect was seen at weeks 7 and 10. In the rats fed HFD containing quercetin, plasma HDLC was increased by 28.6% at week 7 but at week 10, plasma LDLC was increased by 21.2%. Quercetin did not cause any significant changes on the plasma TC, TG and liver fat at weeks 4, 7 and 10. Plasma alanine aminotransferase, alkaline phosphatase and bilirubin in control and treated groups were not significantly different. However, hepatic lipase activity in rats fed tannic acid was significantly lower. Aortae of all groups of rats showed no abnormalities. The present report indicates that tannic acid and morin are effective in reducing plasma and liver lipids when supplemented with a high fat diet in rats.
Subterminal hydroxylation of lauric acid by microsomes from a marine fish
Authors: Lemaire Philippe , Lafaurie Marc , Weissbart Daniel , Durst Francis , Pflieger Philippe , Mioskowski Charles , Salaün Jean‐Pierre 
Published: November 2006

AbstractMicrosomes from the liver of sea bass (Dicentrarchus labrax) were shown to hydroxylate lauric acid at subterminal positions. The cytochrome P‐450 system converted lauric acid to several mono‐hydroxylated metabolites including ω‐1 hydroxylaurate, which was the major metabolite (44% of total products). In addition, ω‐2, ω‐3, ω‐4 and a small amount (2.3%) of ω hydroxylaurates were found. Reaction products were identified using thin‐layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS). Oxidation reactions were dependent upon O2 and NADPH, and did not occur with boiled microsomes or in the presence of a mixture of CO/O2. Hydroxylation proceeded linearly up to 20 min at 28°C for protein concentrations below 380 μg. Treatment of fish with benzo(α)pyrene (BP) (20 mg/kg) drastically increased xenobiotic metabolism (ECOD, EROD and BPMO activities), but no difference in laurate hydroxylase activity was observed between untreated and treated fish. Starvation strongly enhanced laurate hydroxylase activity, and resumption of feeding reduced by half this increase of activity. In all of the experiments we did not observe any modification of the regioselectivity of lauric acid hydroxylation by this microsomal in‐chain hydroxylating system. We suggest that cytochrome P‐450 enzymes involved in lauric acid and xenobiotics metabolism are regulated independently.
A sensitive and specific radioimmunoassay for platelet‐activating factor
Authors: Wang Chang‐jin , Tai Hsin‐Hsiung 
Published: November 2006

AbstractA platelet‐activating factor (PAF) analog with a reactive ω‐aldehyde group at thesn‐1 position was synthesized. The hapten‐thyroglobulin conjugate was used to immunize rabbits to produce specific antibodies to PAF. The purified immunoglobulin G (IgG) fraction was found to bind stereo‐specifically to tritiated PAF and to crossreact minimally with lysoPAF, plasmalogens, and other phospholipids. The radioimmunoassay detected as little as 20 pg of PAF per assay tube and was used to explore agonist‐induced synthesis of PAF in rabbit neutrophils. Calcium ionophore A23187 at 1 μM induced PAF synthesis peaking at 2 min and reaching basal levels after 5 min.N‐Formyl‐Met‐Leu‐Phe (FMLP) at 0.1 μM also stimulated rapid synthesis and degradation of PAF with a peak at 5 min. Both A23187 and FMLP stimulated PAF synthesis in a dose‐dependent manner. The radioimmunoassay should be applicable to the quantitation of PAF in biological samples.
Metals and lipid oxidation. Contemporary issues
Authors: Schaich K. M. 
Published: November 2006

AbstractLipid oxidation is now recognized to be a critically important reaction in physiological and toxicological processes as well as in food products. This provides compelling reasons to understand what causes lipid oxidation in order to be able to prevent or control the reactions. Redox‐active metals are major factors catalyzing lipid oxidation in biological systems. Classical mechanisms of direct electron transfer to double bonds by higher valence metals and of reduction of hydroperoxides by lower valence metals do not always account for patterns of metal catalysis of lipid oxidation in multiphasic or compartmentalized biological systems. To explain why oxidation kinetics, mechanisms, and products in molecular environments which are both chemically and physically complex often do not follow classical patterns predicted by model system studies, increased consideration must be given to five contemporary issues regarding metal catalysis of lipid oxidation: hypervalent non‐heme iron or iron‐oxygen complexes, heme catalysis mechanism(s), compartmentalization of reactions and lipid phase reactions of metals, effects of metals on product mixes, and factors affecting the mode of metal catalytic action.
Redox cycling of iron and lipid peroxidation
Authors: Minotti Giorgio , Aust Steven D. 
Published: November 2006

AbstractMechanisms of iron‐catalyzed lipid peroxidation depend on the presence or absence of preformed lipid hydroperoxides (LOOH). Preformed LOOH are decomposed by Fe(II) to highly reactive lipid alkoxyl radicals, which in turn promote the formation of new LOOH. However, in the absence of LOOH, both Fe2+ and Fe3+ must be available to initiate lipid peroxidation, with optimum activity occurring as the Fe2+/Fe3+ ratio approaches unity. The simultaneous availability of Fe2+ and Fe3+ can be achieved by oxidizing some Fe2+ with hydrogen peroxide or with chelators that favor autoxidation of Fe2+ by molecular oxygen. Alternatively, one can use Fe3+ and reductants like superoxide, ascorbate or thiols. In either case excess Fe2+ oxidation or Fe3+ reduction will inhibit lipid peroxidation by converting all the iron to the Fe3+ or Fe2+ form, respectively. Superoxide dismutase and catalase can affect lipid peroxidation by affecting iron reduction/oxidation and the formation of a (1∶1) Fe2+/Fe3+ ratio. Hydroxyl radical scavengers can also increase or decrease lipid peroxidation by affecting the redox cycling of iron.
Peroxide dependent and independent lipid peroxidation: Site‐specific mechanisms of initiation by chelated iron and inhibition by α‐tocopherol
Authors: Fukuzawa Kenji , Fujii Tomohito 
Published: November 2006

AbstractPeroxidation of linoleic acid (LA) was catalyzed by Fenton reagent (H2O2, and Fe2+) in positively charged tetradecyltrimethylammonium bromide (TTAB) micelles, but not in negatively charged sodium dodecylsulfate (SDS) micelles. However, more hydroxyl radicals formedvia the Fenton reaction were trapped byN‐t‐butyl‐α‐phenylnitrone (PBN) in SDS micelles than in TTAB micelles. Generation of linoleic acid alkoxy (LO) radicals by Fe2+via reductive cleavage of linoleic acid hydroperoxide (LOOH) resulted in peroxidation of LA and formation of PBN‐LO· adducts in SDS micelles, but not in TTAB micelles. This LOOH dependent lipid peroxidation could be catalyzed in TTAB micelles in the presence of a negatively charged iron chelator, nitrilotriacetic acid (NTA). LO radicals formed by the LOOH dependent Fenton reaction were also trapped by PBN at the surface of TTAB micelles in the presence of NTA, but not in its absence. The consumption of a spin probe, 16‐(N‐oxyl‐4,4′‐dimethyloxazolidin‐2‐yl)stearic acid (16‐NS) during the LOOH dependent Fenton reaction in the presence of NTA was higher in TTAB micelles of LA than in those of lauric acid (LauA), although the rates and amounts of LO radicals formed in the two types of fatty acid micelles were similar. The rates of 5‐NS consumption in LA and LauA micelles were almost the same, and were lower than the rate of 16‐NS in LA micelles. NTA‐Fe2+ initiated peroxidation of LA in TTAB micelles without a lag time in the presence of LOOH, but after a lag period, peroxidation occurred without LOOH. α‐Tocopherol inhibited peroxidation of LA catalyzed by Fenton reagent by scavenging OH radicals in TTAB micelles. In contrast, α‐tocopherol enhanced free Fe2+ induced LOOH dependent lipid peroxidation through the regeneration of Fe2+ in SDS micelles. However, it inhibited NTA‐Fe2+ induced LOOH dependent lipid peroxidation in TTAB micelles. The rate and amount of α‐tocopherol oxidized by the Fe2+ induced, H2O2 dependent Fenton reaction were almost the same in TTAB micelles of LA and LauA. The oxidation of α‐tocopherol by the NTA‐Fe2+ induced, LOOH dependent Fenton reaction was greater and faster in LA micelles than in LauA micelles, although the rates of LO radical production in the two types of micelles were the same. During NTA‐Fe2+ induced, LOOH dependent lipid peroxidation, α‐tocopherol inhibited more effectively the consumption of 16‐NS than 5‐NS. The results are discussed in relation to the location of iron, the unsaturated bonding region of LA, the OOH group of LOOH, the radical trapping site of PBN, the spin sites of 5‐NS and 16‐NS, and the phenolic hydroxyl group of α‐tocopherol in micelles with different charges.
Dietary fat ratios and liver plasma membrane lipid composition
Authors: Hamm Michael W. , Sekowski Anna , Ephrat Roni 
Published: November 2006

AbstractMale Sprague‐Dawley weanling rats were fed isocaloric diets consisting of 10% (by wt) fat. The six groups differed in the ratio of corn oil and butter fat present in the diets such that: 10C, 10% corn oil (C); 8C2B, 8% C/2% butter fat (B); 6C4B, 6% C/4% B; 4C6B, 4% C/6% B; 2C8B, 2% C/8% B; and 10B, 10% B. Liver plasma membranes were analyzed for fatty acid composition and cholesterol/phospholipid molar ratio. The 18∶2n−6 content was constant in the 10C and 8C2B diets and then decreased linearly through the 2C8B diet. The 20∶4n−6 and 18∶1n−9 contents were constant except in the 10B diet, in which a significant decrease and increase, respectively, were observed. The cholesterol/phospholipid molar ratio increased between the 10C and 6C4B diets and subsequently (4C6B and 10B diets) remained constant. This data indicates that changes in n−6 fatty acid content in the liver plasma membrane are directly related to dietary intake only for 18∶2n−6. Arachidonic acid content in the membrane is maintained at a constant level until the linoleic acid content of the diet is reduced to 0.5% of calories. It also indicates that the cholesterol content of the membrane becomes saturated and does not increase with increasing concentrations of saturated fat in the diet.
Influence of dietary fats on pancreatic phospholipids of chronically ethanol‐treated rats
Authors: Cronholm Tomas , Neri Aldo , Karpe Fredrik , Curstedt Tore 
Published: November 2006

AbstractMale rats were given liquid diets by pair‐feeding for 24–30 days, and phosphatidylinositols in pancreas were analyzed as derivatives of diacylglycerols and fatty acids. Addition of arachidonic acid or changing the fat component (35 energy%) in the liquid diet from olive oil/corn oil to oil fromBorago officinalis, which contains 22% γ‐linolenic acid, increased the fraction of arachidonoyl‐containing species. This fraction was decreased by more than 50% by substituting ethanol for 36 of the 47 energy% provided by carbohydrate. A smaller difference between ethanol‐fed and control rats was seen in the composition of phosphatidylcholines and phosphatidylethanolamines. There was no difference in the composition of phosphatidylinositols when fat, instead of ethanol, was used to substitute the 36 energy% in the diet containing olive oil/corn oil. Substituting ethanol for 28 of 35 energy% provided by fat as corn oil in a liquid diet had no effect on the fraction of arachidonoyl‐containing species. The results indicate that the effect of ethanol on phosphatidylinositols in pancreas is not due to a deficiency of arachidonic acid, and that the effect of the ethanol‐containing diet is not due to the lowered carbohydrate content. However, high contents of fat or of ethanol appear to be necessary for the effect.
Effects of estrogen‐induced hyperlipidemia on the erythrocyte membrane in chicks
Authors: Simon Cho B. H. , Smith Terrance L. , Park Jeong R. , Kummerow Fred A. 
Published: November 2006

AbstractThe effects of estrogen‐induced hyperlipidemia on plasma lipid peroxidation, fatty acid composition and osmotic fragility of erythrocytes in chickens were studied. Young male chickens implanted with estrogen for three wk developed a marked hyperlipidemia. Plasma levels of triglyceride, cholesterol and phospholipid were elevated 68‐, four‐ and 24‐fold, respectively, over controls. There was also a two‐fold increase in plasma lipid peroxidation measured by the thiobarbituric acid test. Vitamin E supplement (1,000 IU/kg diet) reduced the plasma lipid peroxidation to the control level, but had no effect on the plasma lipid content. Estrogen‐induced hyperlipidemia resulted in changes in the fatty acid composition of membrane lipids of erythrocytes. The major changes were an increase in oleic acid from 10.0% to 14.2% and a decrease in linoleic acid from 31.3% to 26.0%. The erytrocytes with an altered membrane fatty acid composition were found to have an increased osmotic fragility. It was apparent that there was a direct correlation between the oleic acid content and the osmotic fragility of erythrocytes.
Characterization of skin‐surface lipids from the monkey (Macaca fascicularis)
Authors: Nishimaki‐Mogami Tomoko , Minegishi Ken‐ichiro , Takahashi Atushi , Kawasaki Yasushi , Kurokawa Yuji , Uchiyama Mitsuru 
Published: November 2006

AbstractSkin‐surface lipids from the monkeyMacaca fascicularis are composed of sterol esters (38%), cholesterol (4%) and two types of wax diesters, identified as Type II (IIa and IIb, 17% and 40%, respectively). Type IIa contained diesters of 1,2‐alkanediols esterified with two molecules of long‐chain (C14−C34) fatty acids having straight and branched chains. In the diesters IIa, fatty acids shorter than C19 predominated in position 1, and fatty acids longer than C20 predominated in position 2. Type IIb contained diesters of 1,2‐alkanediols esterified with C4 and C5 branched‐chain fatty acids (predominantly isovaleric acid) at position 1 and long‐chain (C14−C27) acids, having straight and branched chains, at position 2. The shortchain acids were converted to 2‐nitrophenylhydrazides and analyzed by high‐performance liquid chromatography (HPLC). Ammonia chemical ionization (CI)‐gas chromatography (GC)‐mass spectrometry (MS) resolved the intact diesters IIb into 12 peaks corresponding to molecular weights ranging from 597 to 748, and showed that the molecular species, such as C21−C16−C5 (diol, fatty acid in position 2, fatty acid in position 1), C22−C16−C5 and C23−C16−C5, were prevalent. The fatty acids from both diesters were mostly (>98%) saturated. The 1,2‐alkanediols from both diesters consisted of C16−C26 saturated straight‐ and branched‐chain components. The acyl groups of sterol esters contained 86% C14−C34 branched‐chain acids. The unsaturated fatty acids (5.4%) belonged to a straight‐chain monoenoic series having extremely long chains (C18−C34). The branched‐chain structures in the fatty acids and diols were iso and anteiso. These results show the species‐specific profile for the skin‐surface lipid synthesis.
Integral lipids of human hair
Authors: Wertz Philip W. , Downing Donald T. 
Published: November 2006

AbstractIt has long been recognized that hair is coated with nonpolar lipids originating in the sebaceous glands, and recently it has been shown that hair also contains cholesterol sulfate and small amounts of ceramides, similar to those found in the keratinized portion of the epidermis. In the present study, it is demonstrated that significant amounts of several additional lipids are tightly associated with hair in such a way as to be highly resistant to solvent extraction.These integral hair lipids included cholesterol sulfate (3.3 mg/g of extracted hair), cholesterol (0.6 mg/g), fatty alcohols (0.2 mg/g) and free fatty acids (4.3 mg/g). The principal fatty acid, comprising 40% of the total fatty acids, was identified as 18‐methyl‐eicosanoic acid by cochromatography with authentic standard on gas‐liquid chromatography (GLC) and by mass spectrometry (MS).
Linoleic acid‐induced fatty acid changes in platelet and aorta of the rat: Effect of age and cholesterol
Authors: Takahashi R. , Horrobin D. F. 
Published: November 2006

AbstractThe influence of age and cholesterol on polyunsaturated fatty acids (PUFa) levels was studied in young and old male Sprague‐Dawley rats. Animals were fed a fat‐free diet supplemented with 10% (by wt) safflower oil with or without 1% cholesterol for 8 wk. As a result of cholesterol feeding, proportions of linoleic acid (18∶2n−6) and dihomo‐γ‐linolenic acid (30∶3n−6) were increased and and that of arachidonic acid (20∶4n−6) was decreased in the liver and platelet phospholipids in 64‐wk‐old rats, suggesting inhibitory effects of cholesterol on 20∶4n−6 synthesis from 18∶2n−6. The prominent age‐dependent effect on the levels of PUFA was a retention of C−22 n−3 PUFA, accompanied by decreased C−22 n−6 PUFA and increased 20∶3n−6 in the liver and platelet phospholipids. Ratio of 20∶3n−6/20∶4n−6 increased in 64‐wk‐old rats regardless of dietary cholesterol, suggesting depressed Δ5‐desaturase with age. In aorta phospholipids, 20∶3n−6 content and 20∶3n−6/20∶4n−6 ratio increased with cholesterol supplementation, but not with age. These results suggest that changes of PUFA composition of platelet phospholipids with age are closely linked with changes in liver phospholipids. The 20∶4n−6 content in both platelet and aorta phospholipids is kept constant, despite other n−6 and n−3 PUFA being affected by age.
Effects of aurothioglucose on iron‐induced rat liver microsomal lipid peroxidation
Authors: Beckman Jeffrey K. , Greene Harry L. 
Published: November 2006

AbstractAurothioglucose (ATG), an inhibitor of selenium‐dependent glutathione peroxidase activity, at a concentration of 100 μM, strongly increases lipid peroxidation of rat liver microsomes exposed to either ferrous ion (10 μM) or the combination of ferric ion (10 μM) and ascorbic acid (500 μM), in the presence of reduced glutathione (GSH, 800 μM). This effect was not achieved using heat‐inactivated microsomes and was dependent on the presence of GSH. ATG did not affect the lag period associated with ascorbic acid/ferric ion‐induced microsomal lipid peroxidation (previously attributed to an undefined GSH‐dependent microsomal agent), but did increase the rate of peroxidation subsequent to the lag period. The potent GSH‐dependent inhibition of microsomal lipid peroxidation by cytosol (10% of total volume) was completely reversed by ATG (100 μM). ATG similarly reversed an inhibition of phosphatidyl‐choline hydroperoxide‐dependent liposomal peroxidation that has been attributed to phospholipid hydroperoxide glutathione peroxidase (PHGPX), an enzyme distinct from the classical glutathione that cannot utilize intact phospholipids.ATG inhibited, in addition to the classifical selenium‐dependent glutathione peroxidase, both cytosolic and microsomal (basal and N‐ethyl maleimide‐stimulated) glutathione S‐transferase activities with greater than 80% inhibition achieved at 100 μM ATG. ATG, at concentrations up to 250 μM, did not inhibit PHGPX activity measured by the coupled‐enzyme method in the presence of Triton X‐100 (0.1%). These data demonstrate the potential of ATG to increase toxicity of lipid peroxidative stimuli by inhibition of microsomal and cytosolic defense mechanisms. Although ATG did not inhibit Triton‐enhanced PHGPX activity, overall evidence points toward inhibition of this enzyme as the mechanism for ATG‐augmented lipid peroxidation and supports the conclusion that PHGPX plays a major role in the cellular defense mechanism.
Cell membrane localization of long chain C24−C30 fatty acids in two marine demosponges
Authors: Lawson Mishelle P. , Thompson Janice E. , Djerassi Carl 
Published: November 2006

AbstractSubcellular fractionation by differential centrifugation was performed on two previously unstudied marine sponges (Reniera sp. andPseudaxinyssa sp.) that represent both major subclasses of the Demospongiae. Long chain fatty acids (LCFA) with 24–30 carbon units were found as major constituents of cell membrane isolates of both sponges. Most LCFA were polyunsaturated and were constituents of the phospholipids, which are typical membrane lipids, and in particular the amino‐phospholipids. The LCFA composition of phospholipids from whole sponge tissue was shown to provide a reliable indication of the LCFA composition of cell membrane phospholipids in the sponges studied. An unusual triply branched C16 isoprenoid fatty acid, 4,8,12‐trimethyltridecanoic acid, also was identified as a cell membrane acid in the spongePseudaxinyssa sp.
Cell membrane localization of sterols with conventional and unusual side chains in two marine demonsponges
Authors: Lawson Mishelle P. , Stoilov Ivan L. , Thompson Janice E. , Djerassi Carl 
Published: November 2006

AbstractSubcellular fractionation by differential centrifugation was performed on two previously unstudied marine sponges that predominantly contain either conventional (Reniera sp.) or unconventional (Pseudaxinyssa sp.) sterols. Direct evidence for the presence of unconventional sterols with C24 alkylated side chains in the cellular membranes ofPseudaxinyssa sp. is provided, but the presence of unconventional sterols in sponge membranes is shown not to be a universal feature of the Porifera. Possible structural and functional roles of unconventional lipid molecules in sponge cell membranes are discussed.