bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation of ethyl hexadec‐1‐enyl ether, a plasmalogen model, in the presence of unsaturated esters
Authors: Marmer William N. , Nungesser Edwin , Foglia Thomas A. 
Published: November 2006

AbstractTo test the susceptibility of plasmalogen lipids to oxidation, a series of experiments was run on the model compound ethyl hexadec‐1‐enyl ether, which was prepared from hexadecanol by a multistep synthesis. Oxidation experiments were carried out on neat mixtures of the model ether with a variety of fatty esters in sealed vials under air. Disappearance of the ether, the fatty esters and, in one set of experiments, oxygen, was followed by gas chromatography. Ethyl stearate, which was inert to oxidation under the experimental conditions, served as internal standard. In the absence of polyunsaturate (linoleate or linolenate), alk‐1‐enyl ether underwent slow but measurable oxidation. In the presence of polyunsaturate, however, disappearance of the ether was greatly accelerated and proceeded at a rate comparable to that of the polyunsaturate. Reactions did not proceed in the absence of oxygen and were inhibited by antioxidant. The results suggest that oxidation of the alk‐1‐enyl ether functionality of plasmalogens should not be ignored as a factor that contributes to the oxidative instability of animal tissue or the development of rancidity in meat products.
The influence of dietary manipulation with n−3 and n−6 fatty acids on liver and plasma phospholipid fatty acids in rats
Authors: Nassar B. A. , Huang Y. S. , Manku M. S. , Das U. N. , Morse N. , Horrobin D. F. 
Published: November 2006

AbstractThe interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague‐Dawley rats (200–220 g) were fed a fat‐free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose oil (EPO), a rich source of LA and γ‐linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% EPO‐1% POL, 8% EPO‐2% POL, 7% EPO‐3% POL, 6% EPO‐4% POL and 5% EPO‐5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo‐γ‐linolenic acid (DGLA) (p<0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid (AA) (p<0.01), a metabolite of DGLA through Δ‐5‐desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA levels was found to exist (r=−0.765 in plasma and −0.792 in liver). However, there was no such relationship between AA/DGLA ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.
A comparison of pyrrolidide and picolinyl ester derivatives for the identification of fatty acids in natural samples by gas chromatography‐mass spectrometry
Authors: Christie William W. , Brechany Elizabeth Y. , Johnson Susan B. , Holman Ralph T. 
Published: November 2006

AbstractThe pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary phases of varying polarity. The picolinyl esters, in particular, when subjected to gas chromatography‐mass spectrometry on a column containing a cross‐linked methyl silicone, gave distinctive mass spectra, which could be interpreted in terms of both the numbers and positions of the double bonds.
Pyrophosphatidic acid in mushrooms
Authors: Sugai Akihiko , Itoh Toshihiro , Kaneko Hiroshi , Kinjo Noriko , Muramatsu Toshio 
Published: November 2006

AbstractThe distribution of pyrophosphatidic acid in mushrooms was investigated. Total lipids of mushrooms were extracted from their fruit body, and the pyrophosphatidic acid fraction was isolated by DEAE‐silica gel column and silicic acid column chromatography. The presence of pyrophosphatidic acid was tested by thin layer chromatography. Of the 43 species of mushrooms examined, the acid was found in 30. The pyrophosphatidic acid was identified by chromatography, IR spectroscopy and quantitative degradation with aqueous pyridine to produce phosphatidic acid. Chemically synthesized pyrophosphatidic acid was used as standard.
Growth hormone and liver mitochondria: Effects on phospholipid composition and fatty acyl distribution
Authors: Clejan Sanda , Maddaiah Vaddanahally T. 
Published: November 2006

AbstractEffects of growth hormone on phospholipid composition and fatty acyl distribution were studied in liver mitochondria of hypophysectomized rats. After hypophysectomy, only cardiolipin showed a 25% decrease. Its fatty acyl distribution, which consisted mainly of linoleic acid (55–60%) and oleic acid (20%), was unchanged. In phosphatidylcholine and phosphatidylethanolamine fractions the contents of docosahexaenoic and arachidonic acids were decreased with a concomitant increase in linoleic acid content. These changes could be accounted for by small but significant decreases in the activities of Δ9‐desaturase (sucrose‐induced), Δ5‐desaturase and mitochondrial elongation enzymes. The activities of Δ6‐desaturase NADH cytochrome b5 ferri‐reductase, cytochrome b5, NADH cytochrome c reductase and microsomal elongation enzymes remained virtually unchanged. Injection of bovine growth hormone daily for seven days restored cardiolipin and fatty acyl distribution and the enzyme activities. From these and other results, we conclude that growth hormone‐dependent increase of respiratory activity of liver mitochondria may be partly mediated by the hormonal effects on membrane lipid distribution.
Animal foods in traditional Australian aboriginal diets: Polyunsaturated and low in fat
Authors: Naughton Joan M. , O'Dea Kerin , Sinclair Andrew J. 
Published: November 2006

AbstractAustralian Aborigines develop high frequencies of diabetes and cardiovascular diseases when they make the transition to an urban lifestyle. The composition of the traditional diet, particularly its lipid components, is a most important aspect of the hunter‐gatherer lifestyle that would bear on the risk of these diseases. We have examined the fat content and fatty acid composition of a variety of animal foods eaten traditionally by Aborigines from different regions of Australia. The muscle samples of the wild animals from all over Australia were uniformly low in fat (<2.6% wet weight) with a high proportion of polyunsaturated fatty acids (≥20% PUFA). Liver samples had a higher range of fat content (5–10% wet weight) but were also rich in PUFA (33–42%). Depot fat samples varied widely in their PUFA content (5–40%). In terms of their PUFA composition the foods tended to fall into three groups: (i) those rich in both n−3 and n−6 PUFA, which included land‐based, coastal and freshwater animals; (ii) those rich in n−3 PUFA, i.e., marine species; (iii) those rich in n−6 PUFA, mainly land‐based species. The results of these analyses suggest that even when the traditional Aboriginal diet contained a high proportion of animal foods it would have been low in fat with a high proportion of PUFA and thereby could have protected Aborigines against cardiovascular diseases and related conditions through a combination of factors: low energy density, low saturated fat and relatively high PUFA content.
Correlation of side chain mobility with cholesterol retention by phospholipid vesicles
Authors: Jacobsohn Myra K. , Estahani Mojtaba , Jacobsohn Gert M. 
Published: November 2006

AbstractMultilamellar vesicles were prepared from choline phospholipids with various fatty acyl chains, singly and in mixtures, with and without cholesterol. Mobility of acyl side chains for each type of vesicle was measured by fluorescence polarization with diphenylhexatriene, and the amounts of cholesterol and phospholipid retained by them after extraction with a nonpolar solvent were determined. The data suggest that structures of acyl chains determine the extractability of cholesterol. Phosphatidylcholines with unsaturated or short saturated side chains above transition temperature retain less cholesterol upon extraction with petroleum ether than phosphatidylcholines with saturated side chains below transition temperature. Correlation of cholesterol retention with side chain mobility showed that cholesterol is more easily removed from vesicles with mobile acyl side chains than from vesicles with rigid side chains. The presence of cholesterol also alters extractability of phospholipids from vesicles and suggests that sterol affects the polarity rather than spacing of headgroups on vesicle surfaces.
Effects of dietary linolenate on the fatty acid composition of brain lipids in rats
Authors: Anding Roberta H. , Hwang Daniel H. 
Published: November 2006

AbstractWeanling male rats were fed hydrogenated coconut oil to induce essential fatty acid (EFA) deficiency. After 15 weeks, the rats were divided into six groups. Five groups were fed graded amounts of purified linolenate (18∶3ω3) with a constant amount of linoleate (18∶2ω6) for six weeks. Fatty acid composition was determined in brain lipids. Increasing dietary 18∶3ω3 resulted in a decrease in arachidonic acid (20∶4ω6), docosatetraenoic acid (22∶4ω6) and docosapentaenoic acid (22∶5ω6), whereas 18∶2ω6 and eicosatrienoic acid (20∶3ω6) were increased both in total lipids and phospholipids. These results suggest that dietary 18∶3ω3 exerts its inhibitory effect mainly on the desaturation of 20∶ω6 to 20∶4ω6 in brain lipids. Linolenate was undetectable in brain lipids from any dietary treatments. The levels of eicosapentaenoic acid (20∶5ω3) in groups receiving dietary 18∶3ω3 were not different from that of the group receiving no 18∶3ω3. These results indicate that, in the brain, 18∶3ω3 is rapidly converted mainly to 22∶6ω3 without being accumulated and imply that dietary 18∶3ω3 can modulate the level of precursor of diene prostaglandins (PG) but not that of triene PG in the rat brain.
Glucosylceramide and the level of the glucosidase‐stimulating proteins
Authors: Datta Subhash C. , Radin Norman S. 
Published: November 2006

AbstractThe concentration of β‐glucosidase‐stimulating proteins (called cohydrolase here) was measured in mouse liver and brain by immunoassay. Factors that might influence the levels of cohydrolase were examined. Injecting mice with an inactivator of glucosidase (conduritol B epoxide) rapidly produced elevations in liver glucosylceramide (the enzyme's substrate) and in liver and brain cohydrolase. Injection of glucosylceramide emulsified with Myrj 52 produced the same two effects in liver but not in brain. The increases in cohydrolase level induced by the enzyme inhibitor persisted in both organs for at least seven days, reaching 61–70% above the normal level. Injection of emulsified galactocerebroside, sphingomyelin and mixed glucosphingolipids but not of ceramide also produced rises in cohydrolase level. An increase in cohydrolase level resulted from injection of phenylhydrazine, which produces hemolysis and consequently an increased workload for the glucosidase of liver. When the enzyme inhibitor and/or larger amounts of glucosylceramide emulsion were injected (750 mg/kg body weight), increases in liver weight of 13 to 37% appeared within one day. The increased weight was characterized by increases in the weights of protein, total lipid and DNA and a very high increase in glucosylceramide level. These procedures have produced a rapidly developing model version of Gaucher disease in mice. Injected glucocerebroside also induced an elevated level of glucosidase activity.
An improved method for the separation of molecular species of cerebrosides
Authors: Hirabayashi Yoshio , Hamaoka Akira , Matsumoto Makoto , Nishimura Kenji 
Published: November 2006

AbstractA method employing reversed‐phase high performance liquid chromatography (HPLC) has been developed for the analysis of molecular species of underivatized cerebrosides. By using a high carbon (20%) C18‐silica bead column, monohexosylceramides isolated from bovine brain and Japanese quail intestine could each be separated into 42 and 56 peaks, respectively, and could subsequently be recovered. Under our analytical conditions, underivatized cerebrosides with 24∶1 and 22∶0 fatty acids were completely separated by single step HPLC. Each of the molecular species was then analyzed by high performance thin layer chromatography and gas chromatography‐mass spectrometry (or fast atom bombardment mass spectrometry). This analytical method permits the complete identification of molecular species of glycosphingo‐lipids.
Desaturation of fatty acids inTrypanosoma cruzi
Authors: de Lema Mirta G. , Aeberhard Ernesto E. 
Published: November 2006

AbstractUptake and metabolism of saturated (16∶0, 18∶0) and unsaturated [18∶1(n−9), 18∶2(n−6), 18∶3(n−3)] fatty acids by cultured epimastigotes ofTrypanosoma cruzi were studied. Between 17.5 and 33.5% of the total radioactivity of [1‐14C]labeled fatty acids initially added to the culture medium was incorporated into the lipids ofT. cruzi and mostly choline and ethanolamine phospholipids. As demonstrated by argentation thin layer chromatography, gas liquid chromatography and ozonolysis of the fatty acids synthesized, exogenous palmitic acid was elongated to stearic acid, and the latter was desaturated to oleic acid and 18∶2 fatty acid. The 18∶2 fatty acid was tentatively identified as linoleic acid with the first bond in the Δ9 position and the second bond toward the terminal methyl end. Exogenous stearic acid was also desaturated to oleic and 18∶2 fatty acid, while oleic acid was only converted into 18∶2. All of the saturated and unsaturated fatty acids investigated were also converted to a small extent (2–4%) into polyunsaturated fatty acids. No radioactive aldehyde methyl ester fragments of less than nine carbon atoms were detected after ozonolysis of any of the fatty acids studied. These results demonstrate the existence of Δ9 and either Δ12 or Δ15 desaturases, or both, inT. cruzi and suggest that Δ6 desaturase or other desaturases of the animal type are likely absent in cultured forms of this organism.
Effect of malonyl‐CoA on Δ6 desaturation activity of rat liver microsomes
Authors: de Gomez Dumm Irma N. T. , de Alaniz Maria J. T. , Brenner Rodolfo R. 
Published: November 2006

AbstractThe effect of malonyl‐CoA on linoleic acid desaturation and elongation reactions of rat liver microsomes was studied. Under strict desaturation conditions, the in vitro microsomal conversion of linoleic acid to γ‐linolenic acid is time‐dependent. When malonyl‐CoA was added to the aforementioned incubation medium, linoleic acid was desaturated to γ‐linolenic acid and elongated to its higher homologues. Under these conditions, Δ6 desaturation activity, calculated by adding γ‐18∶3, 20∶3 and 20∶4 acids, was neither inhibited nor activated by malonyl‐CoA. These results indicate that the elongation of γ‐linolenyl‐CoA coupled to the desaturation of linoleic acid did not modify Δ6 desaturase activity.
Growth support and metabolism of phytosterols inParamecium tetraurelia
Authors: Whitaker Bruce D. , Nelson David L. 
Published: November 2006

AbstractThe basis of the growth requirement ofParamecium for one of several structurally similar phytosterols is not known. Previous research has indicated that selective esterification of only growth‐promoting sterols may be a key. In this study, it was found that under certain conditions sterols that fail to support growth (e.g., cholesterol) can be esterified in large amounts inParamecium. We found no compelling evidence to support the hypothesis that steryl esters serve a specialized role in the fatty acid metabolism of the cell. Octadecenoic acid, essential for cell growth, was the major fatty acid in both steryl esters and triglycerides. It was also shown thatP. tetraurelia can dehydrogenate Δ0 and Δ7, as well as Δ5‐3β‐hydroxy sterols, to yield the conjugated 5,7‐diene derivative. These results indicate the presence of a Δ5, in addition to a Δ7, desaturase of the sterol nucleus in this ciliate. Two C24 α‐ethyl sterols, Δ22‐stigmasterol (Δ22) and stigmastanol (Δ0), were shown for the first time to promote growth. Finally, we found that non‐growth‐promoting sterols may compose a high percentage of the free sterols of the surface membrane without adversely affecting cell growth or viability. These data support the conclusion that the growth requirement for select phytosterols inParamecium does not involve the structural or functional role of “bulk” sterols in cell membranes.
Lipid peroxidation in erythrocyte membranes: Cholesterol product analysis in photosensitized and xanthine oxidase‐catalyzed reactions
Authors: Girotti Albert W. , Bachowski Gary J. , Jordan John E. 
Published: November 2006

AbstractThe effects of singlet oxygen‐ and oxygen radical‐induced lipid peroxidation on cell membrane integrity were compared, using the human erythrocyte ghost as a model system. Resealed ghosts underwent lipid peroxidation and lysis (release of trapped glucose‐6‐P) when irradiated in the presence of uroporphyrin (UP) or when incubated with xanthine (X), xanthine oxidase (XO) and iron. The UP‐sensitized process was inhibited by azide but not by phenolic antioxidants, consistent with singlet oxygen (nonradical) involvement. This was confirmed by showing that the predominant photoproduct of membrane cholesterol was the 5α‐hydroperoxide. Total hydroperoxide (LOOH) content in UP‐photooxidized ghosts increased linearly during the prelytic lag and throughout the period of rapid lysis. Unlike the photoreaction, X/XO/iron‐dependent peroxidation and lysis was inhibited by catalase, superoxide dismutase and phenolic antioxidants, indicating O2−/H2O2 intermediacy and a free radical mechanism. Correspondingly, only radical reactions products of cholesterol were formed, notably the 7α‐, 7β‐hydroperoxide pair. Membranes lysis had a distinct lag as in photooxidation; however, the LOOH profile was more complex, with an initial lag followed by a sharp increase and then slow decline. X/XO/iron‐induced lysis commenced when LOOH levels were 2–3 times higher than in photosensitized lysis, suggesting that the pathways of membrane lesion formation are different in the two systems. In low concentrations, ascorbate exacerbated the damaging effects of photoperoxidation, switching the reaction from primarily singled oxygen‐ to oxygen radical‐dependence, as indicated by cholesterol product analysis.
Effects of fatty acids on gap junctional communication: Possible role in tumor promotion by dietary fat
Authors: Aylsworth Charles F. , Welsch Clifford W. , Kabara Jon J. , Trosko James E. 
Published: November 2006

AbstractDietary lipids, in particular unsaturated fat, promote the development of many experimental tumors. However, no mechanisms to fully explain these effects have been elucidated. Recent reports, which we summarize here, suggest a role for gap junction‐mediated intercellular communication in the process of tumor promotion. We also review tumor‐promoting effects of dietary fat on experimental, particularly mammary, carcinogenesis. Our main focus is to review recent data examining the inhibitory effects of unsaturated fatty acids on metabolic cooperation in Chinese hamster V79 cells. These data suggest that inhibition of junctional communication may be involved mechanistically in the promotion of tumors by high levels of dietary unsaturated fat. Finally, potential mechanisms by which unsaturated fatty acids inhibit metabolic cooperation are examined.
The influence of dietary medium chain triglycerides on rat mammary tumor development
Authors: Cohen L. A. , Thompson D. O. 
Published: November 2006

AbstractThe N‐nitrosomethylurea rat mammary tumor model was used to compare the tumor‐promoting effects of a highfat (HF) diet containing a 3:1 mixture of medium chain triglycerides (MCT) and corn oil with that of a HF and a low‐fat (LF) corn oil diet. The serum and tumor lipid content and fatty acid (FA) composition were also determined in the three dietary groups. It was found that the MCT‐containing diet failed to promote tumor development compared with the HF corn oil group. Tumor incidence in the HF‐MCT group was similar to that of the LF corn oil group (5% fat, w/w), but significantly decreased compared to the HF corn oil group. Total serum cholesterol levels were significantly depressed in the HF corn oil group compared to the HF‐MCT and LF corn oil groups. Analysis of serum and tumor FA profiles indicated that the HF corn oil group exhibited approximately twice the amount of linoleic acid (LA) as the other two treatment groups. Differences among the three groups in the major FA metabolite of LA, arachidonic acid, were minimal. These results are consistent with the hypothesis that tumor promotion by dietary fat is more a function of the type than the amount of fat ingested. In addition, they indicate that MCT, due at least in part to their unique structural and physiological properties, exert markedly different effects on mammary tumor development than conventional long chain unsaturated fatty acids.
In vivo incorporation of labeled fatty acids in rat liver lipids after oral administration
Authors: Leyton J. , Drury P. J. , Crawford M. A. 
Published: November 2006

AbstractStriking differences were found in the compartmentalization of fatty acids into liver lipid fractions. The saturated fatty acids—lauric, myristic, palmitic and stearic—were incorporated into phosphoglycerides at faster rates with increasing chain lengths, while triglyceride incorporation was almost uniform. The degree of incorporation of the unsaturated fatty acids into phosphoglycerides (structural) compared to triglyceride (storage and energy) was the converse of their oxidation rates. The incorporation of oleic, linoleic and α‐linolenic acids was mainly into triglyceride, whereas dihomo‐γ‐linolenic acid and arachidonic acid were preferentially incorporated into phosphoglycerides. The data suggest that distribution of each fatty acid is different depending on its destination for structural or energy function.
Partial purification and characterization of free and immobilized lipases from Mucor miehei
Authors: Huge‐Jensen Birgitte , Galluzzo Donna Rubano , Jensen Robert G. 
Published: November 2006

AbstractAn extracellular lipase, a glycoprotein, produced by fermentation with a selected strain ofMucor miehei has been partially purified in two forms, A and B. The two forms have a high degree of antigenic identity and have similar pH‐activity profiles with tributyroylglycerol as a substrate with optima at pH 7. They differ as follows: A, in contrast to B, requires activation at alkaline pH before analysis; A binds with concanavalin‐A more completely than B; the net charges are slightly different at pH 8; and the isoelectric points are different. Our results indicate that the B lipase is formed by partial deglycosylation of the A lipase and that this influences the activity toward emulsions.In addition, the two enzymes have been immobilized by adsorption. These preparations and the soluble forms were highly specific for primary esters of triacylglycerols (TG); they usually hydrolyzed TG of 12∶0, 14∶0, 16∶0, and 18∶1 more rapidly than those of 4∶0, 6∶0, and 8∶0 and 10∶0 in mixtures of monoacid TG (4∶0 to 18∶1); and they were not stereospecific for TG. Immobilization altered the specificity of the preparations somewhat, in that slightly more 14∶0 and 16∶0 were released.