bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of epinephrine on the oxidative desaturation of fatty acids in the rat adrenal gland
Authors: Mandon Elisabet C. , de Gomez Dumm Irma N. T. , Brenner Rodolfo R. 
Published: November 2006

AbstractDelta‐6 and Δ5 desaturation activity of rat adrenal gland microsomes was studied to determine the effect of microsomal protein and the substrate saturation curves. This tissue has a very active Δ6 desaturase for linoleic and α‐linoleic acids and a Δ5 desaturase for eicosa‐8,11,14‐trienoic acid. The administration of epinephrine (1 mg/kg body weight) 12 hr before killing, produced approximately a 50% decrease in desaturation of [1‐14C]linoleic acid to γ‐linolenic acid, [1‐14C]α‐linolenic acid to octadeca‐6,9,12,15‐tetraenoic acid and [1‐14C]eicosa‐8,11,14‐trienoic acid to arachidonic acid. A 30% decrease in Δ5 desaturation activity was also shown after 7 hr of epinephrine treatment. The changes on the oxidative desaturation of the same fatty acids in liver microsomes were similar. No changes were observed in the total fatty acid composition of adrenal microsomes 12 hr after epinephrine treatment. Mechanisms of action of the hormone on the biosynthesis of polyunsaturated fatty acids in the adrenal gland are discussed.
High performance liquid chromatographic separation of monoacylglycerol enantiomers on a chiral stationary phase
Authors: Itabashi Yutaka , Takagi Toru 
Published: November 2006

AbstractHigh performance liquid chromatographic separation of monoacylglycerol enantiomers as di‐3,5‐dinitrophenylurethane derivatives was carried out on a chiral stationary phase, N‐(S)‐2‐(4‐chlorophenyl)isovaleroyl‐D‐phenylglycine chemically bonded tov‐aminopropyl silanized silica. Complete separation of the urethane derivatives of racemic monoacylglycerols with saturated acyl groups of C12−C18 was achieved using a stainless steel column (25 cm long) packed with the 5μ particles, an isocratic elution at ambient temperature with a mixture of hexane/ethylene dichloride/ethanol as a mobile phase, and a UV detector. Thesn‐1 enantiomers were eluted ahead of the correspondingsn‐3 enantiomers. Complete separation of thesn‐2 isomers from the corresponding enantiomers and partial separation of the enantiomer homologues differing by two acyl carbons also were observed.
Effect of candicidin on cholesterol and bile acid metabolism in the rat
Authors: Singhal Anil K. , Mosbach Erwin H. , Schaffner Carl P. 
Published: November 2006

AbstractSterol metabolism studies were carried out in rats maintained on a diet containing a polyene antibiotic, candicidin, (30 mg/kg/day) for 2‐1/2 months. Compared to the controls, the candicidintreated animals had a smaller food intake and weight gain during this period. There was no difference between the 2 groups in serum cholesterol levels, biliary cholesterol or bile acid concentrations. However, in the experimental group, liver cholesterol content decreased by 27% and hepatic HMG‐CoA reductase increased by 36%. Candicidin administration produced an 84% increase in neutral sterol output without change in bile acid output. Cholesterol absorption was reduced 80% by candicidin feeding. The weight of ventral prostate was reduced 33% by candicidin administration. Prostatic HMG‐CoA reductase levels were 3 times higher than those of the liver, but enzyme activity was unchanged by candicidin treatment.
Structural analysis of hydroperoxides formed by oxidation of phosphatidylcholine with singlet oxygen
Authors: Terao J. , Hirota Y. , Kawakatsu M. , Matsushita S. 
Published: November 2006

AbstractSoybean phosphatidylcholine (PC) and dilinoleoyl PC (di‐18∶2 PC) were oxidized with singlet molecular oxygen using methylene blue as the photosensitizer. The oxidation products, PC monohydroperoxides (PC‐MHP) and PC dihydroperoxides (PC‐DHP), were isolated by reverse phase liquid chromatography, and their structures were analyzed by nuclear magnetic resonance (NMR) and gas chromatography‐mass spectrometry (GC‐MS). Signals for the hydroperoxy proton appeared downfield in NMR spectra of PC‐MHP and PC‐DHP. Soybean PC‐MHP and di‐18∶2 PC‐MHP were converted to trimethylsilyl (TMS) derivatives of hydrogenated diglycerides when treated with phospholipase C and hydrogenated. Thetert‐butyldimethylsilyl (TBDMS) derivatives of hydrogenated diglycerides were also prepared from di‐18∶2 PC‐MHP. Fragmentation of the TMS and TBDMS derivatives was obtained in electron impact mass spectra. The isomeric composition of hydroperoxylinoleate component in di‐18∶2 PC‐MHP was determined by methanolysis of the hydrogenated diglyceride and mass chromatographic analysis of the resulting isomeric hydroxy octadecanoates.
Effect of polyestradiol on lecithin:cholesterol acyltransferase in male and female rats
Authors: Gandarias J. M. , Lacort M. , Ochoa B. , Quiroga M. 
Published: November 2006

AbstractThe effects of two doses of polyestradiol phosphate on lecithin:cholesterol acyltransferase activity and on liver and plasma cholesterol levels have been studied on female and male rats. Both treatments increased the hepatic content of esterified cholesterol, but the LCAT activity expressed as a percentage of cholesterol esterification was unaltered. The progress of esterification was not affected by the administration of the hormone. The LCAT activity in terms of the initial rate of esterification was decreased by the high dose of estradiol. This decrease was associated with a reduction of free plasma cholesterol level, as there is a significant positive correlation between these two parameters. The findings suggest that the increased esterified cholesterol in liver of estradiol‐treated rats is not mediated by an alteration in the LCAT activity.
Effect of water mobility on lateral diffusion of phospholipids in liposomes
Authors: Wu Wen‐Guey , Huang Ching‐Hsien 
Published: November 2006

AbstractRecently, several studies have shown that the rate of lateral diffusion of liquid‐crystalline phospholipids in various phospholipid/water lamellar systems depends markedly on the hydration over the water content of 15–40 w/w%. In this paper, we calculated the change in lipid lateral diffusion as a function of water content according to the theory of Brownian motion in thin sheets developed by Saffman and Delbrück. These calculations, based on experimental data of lipid dimensions and bulk water diffusion coefficients obtained for the egg phosphatidylcholine/water system at various water contents, clearly indicate that the dependence of lipid lateral diffusion on the hydration can be attributed primarily to the change in bulk water mobility in the multilamellar phospholipid/water system.
Glycerolipid biosynthesis in rat adipose tissue: VIII. Effect of obesity and cell size on [14C]acetate incorporation into lipids
Authors: Jamdar Subhash C. , Osborne Linda J. 
Published: November 2006

Abstract[14C]Acetate incorporation into different lipid fractions was measured as a function of adipocyte size by using the larger and smaller adipocytes derived from Sprague‐Dawley rats. In both the larger and smaller adipocytes, [14C]acetate was incorporated into phospholipid, diacylglycerol, free fatty acid and triacylglycerol fractions. Although the rates of lipid formation were significantly higher in the larger adipocytes compared to the smaller ones, the proportions of the various lipids formed from [14C]acetate did not change significantly as a function of cell size. In some experiments, isolated adipocytes derived from obese Zucker rats were fractionated further to isolate an adipocyte preparation which was similar in size to those obtained from lean animals. The matching adipocytes derived from lean and obese animals did not differ significantly with respect to lipid formation from [14C]‐acetate. These studies suggest that the larger adipocytes are more active in lipogenesis from [14C]‐acetate than the smaller ones and that the increased capacity of lipogenesis in obese adipose tissue noted proviously (Biochem. J., 170, 153–160, 1978) is not an intrinsic property of all the obese adipocytes, but is limited mainly to the larger adipocytes.
Potential bile acid metabolites: IV. Inversion of 7α‐hydroxyl; ursodeoxycholic acid
Authors: Iida Takashi , Taneja Hans R. , Chang Frederic C. 
Published: November 2006

AbstractA new method for inversion of chenodeoxycholic to ursodeoxycholic acid which does not involve an intermediary ketone is described. Methyl chenodeoxycholate‐3‐cathylate‐7‐mesylate undergoes a mild reaction with potassium superoxide‐18‐crown ether‐6 in DMSO to give ursodeoxycholic acid in good yield.
Transformation of arachidonic acid into monohydroxy‐eicosatetraenoic acids by mouse peritoneal macrophages
Authors: Rabinovitch Hélène , Durand Jacqueline , Rigaud Michel , Mendy Francois , Breton Jean‐Christian 
Published: November 2006

AbstractMouse peritoneal macrophages synthesize 6 monohydroxylated eicosatetraenoic acids when incubated with exogenous arachidonic acid. These compounds were identified by chromatographic techniques (high pressure liquid chromatography and high efficiency glass capillary column gas chromatography and mass spectrometry. The chromatographic and spectrometric data are presented. These results show that peritoneal macrophages constitute one of the best systems to study in evaluating the metabolism of oxygenated products of arachidonic acid.
Different thermal behavior of neonatal hepatic and cerebral 3‐hydroxy‐3‐methylglutaryl‐CoA reductase
Authors: Ramirez H. , Alejandre M. J. , Segovia J. L. , Garcia‐Peregrin E. 
Published: November 2006

AbstractThe Arrhenius plots of hepatic and cerebral 3‐hydroxy‐3‐methylglutaryl‐CoA reductase activity were studied in neonatal chicks fed with a standard diet. Supplementation of the diet with 2% cholesterol from hatching has no effect on the thermal characteristics of the brain enzyme. The Arrhenius plot of brain reductase was practically similar to that found in control chicks. However, hepatic reductase was inhibited by cholesterol feeding. Dietary cholesterol increased the cholesterol/lipidic phosphorus molar ratio in liver microsomes, whereas no significant differences were observed in brain microsomes. These results are in agreement with the hypothesis that activity of hepatic reductase is regulated by the fluidity of microsomal membrane and show that cholesterol feeding does not alter the fluidity of microsomal membranes in neonatal chick brain having, thus, no effect on the thermal behavior of cerebral reductase.
Incorporation into lipid classes of products from microsomal desaturation of isomerictrans‐octadecenoic acids
Authors: Riisom T. , Holman R. T. 
Published: November 2006

AbstractThe microsomal desaturation of positional isomers oftrans‐octadecenoic acids is effected by the Δ9‐desaturase and, with concomitant geometric isomerization,cis,trans‐ andcis,cis‐octadecadienoic acids of unusual structure are formed. Incorporation of the substrates and their products into lipids varied from 50.5% for incubations with 14–18∶1 to 81.0% for 6–18∶1. A detailed study of the composition of each of the major lipid classes, i.e., phospholipids, triacylglycerol and cholesteryl esters, as well as the composition of the free fatty acid fraction, revealed a complex picture. Generally, thec,c‐18∶2 products were enriched in the phospholipid fraction, whereas thec,t‐18∶2 appeared preferentially in cholesteryl esters. The 18∶1 substrates themselves did not show marked preferences for any of the lipid classes. Phospholipase A2 action on phosphatidylcholine and phosphatidylethanolamine demonstrated enrichment of thec,c‐ and thec,t‐18∶2 products in the 2‐position, whereas the 18∶1 substrates were preferentially inserted into the 1‐positions. Thec,c‐ andc,t‐18∶2 formed by desaturation oft11–18∶1 varied from this pattern, probably due to their conjugated double bond structures. Linoleic acid,c9,c12–18∶2, formed during desaturation oft12–18∶1, surprisingly showed enrichment in the 1‐position of phosphatidylcholine. Incubation experiments witht5‐ andt6‐isomers using liver microsomes from rats fed a corn‐oil‐supplemented diet showed conversion and incorporation rates similar to the rates obtained with microsomes from EFA‐deficient rats. The fatty acid composition of lipid classes and the distributions of products and substrate between the 1‐ and 2‐positions of phosphatidylcholine also agreed with results obtained using microsomes from EFA‐deficient rats.
Biohydrogenation of cholesterol as an index of bacterial 7α‐dehydroxylase activity
Authors: Huang Charles T. L. , Levine M. M. , Woodward W. E. , Gopalakrishna G. S. , Nalin D. R. , Hornick R. B. , Nichols B. L. 
Published: November 2006

AbstractFecal steroid compositions of 82 human subjects of various ages and diets and gastrointestinal status were examined by gas liquid chromatography. Progressive increases in bacterial activities on both bile acids and neutral sterols were observed with the advance of age in infants and children. The patterns in the 4‐year‐olds approached those observed in adults. Bacterial activites on fecal steroids were found to be decreased in adult subjects with acute shigellosis and in those challenged by castor oil. In contrast, no significant changes in fecal steroid profiles were observed in the subjects with traveller's diarrhea assoicated with toxigenicEscherichia coli. The effects of diarrhea on fecal steroids of infants under 11/2 years were less consistent than those of adults. However, a close relationship was observed between the degree of 7α‐dehydroxylation of cholic acid (expressed as the ratio of deoxycholic to the sum of deoxycholic and cholic acids) and the percentage of cholesterol in the feces (r= 0.921, p<0.001). The correlation between the production of lithocholic acid and the percentage cholesterol was also good (r=−0.739, p<0.001). Analysis of neutral steroids may be a good index of intraluminal bile acid metabolism.
Effect of the environment and fasting on the lipid and fatty acid composition ofDiplodom patagonicus
Authors: Pollero Ricardo J. , Brenner Rodolfo R. 
Published: November 2006

AbstractSome effects of food, habitat and temperature on the lipid composition of a freshwater mollusk,Diplodom patagonicus, were studied. Animals kept and fasted up to 60 days in an aquarium at 9 C and 20 C showed a decrease of the total lipid content that corresponded to a decrease of triacylglycerols and diacylglycerol ethers. This decrease evoked an increase of polar‐to‐nonpolar lipid ratio. However, no significant change in the total fatty acid composition was shown. Moreover, a decrease of temperature from 20 C to 9 C decreased the incorporation of labeled linoleic and α‐linolenic acid into the lipids, but did not modify the unsaturated: saturated acid ratio of the mollusk lipids during this period. A change of habitat from lake to estuary changed very significantly the fatty acid composition of the animal. The ω6 acids, linoleic and arachidonic, typical ofD. patagonicus living in the lake, were partially replaced by ω3 acids. That this change was due to a change of food composition was indicated by the fatty acids of corresponding sediments. Therefore, the fatty acid composition ofD. patagonicus is highly sensitive to food composition and varies little with temperature and seasonal changes.
Separation of pairs of C‐24 epimeric sterols by glass capillary gas liquid chromatography
Authors: Thompson Raymond H. , Patterson Glenn , Thompson Malcolm J. , Slover Hal T. 
Published: November 2006

AbstractParis of C‐24 epimeric sterols have been very difficult to separate by physical emthods. We report here the partial or complete separation of the trimethylsilyl ethers of nine pairs of C‐24 epimeric sterols by gas liquid chromatography on a glass capillary column coated with SP‐2340. The trimethylsilyl ethers of the epimeric pairs of sterols with saturated side chains and a pair with two double bonds in the side chain were completely separated from each other by GLC. The epimeric pairs with a double bond at C‐22 showed partial separation. The 24β‐epimer with a saturated side chain eluted before the corresponding 24α‐epimer. This order was reversed for pairs of C‐24 epimeric sterol trimethylsilyl ethers containing a double bond in the side chain at C‐22.
Effect of essential fatty acid depletion on tissue phospholipid fatty acids in spontaneously hypertensive and normotensive rats
Authors: Huang Yung‐Sheng , Mills Dave E. , Ward Ron P. , Horrobin David F. , Simmons Valerie A. 
Published: November 2006

AbstractWeanling male spontaneously hypertensive (SHR) and normotensive (WKY) rats were maintained on a fat‐free semisynthetic diet and killed at various intervals. The effects of fat‐depletion on the appearance of essential fatty acid (EFA) deficiency symptoms, the progressive changes of major fatty acids in plasma, liver, heart, and kidney phospholipids (PL), and in skin total lipids were compared between these two strains. After five weeks on the diet, the slower growth and the appearance of EFA deficiency symptoms became evident in SHR. In general, fat‐depletion reduced the levels of n−6 fatty acids, whereas it increased those of 20∶3n−9. However, the fat‐depletion induced reduction of 18∶2n−6 in heart PL and 20∶4n−6 in kidney, while the elevation of 20∶3n−9 in plasma, heart, and kidney PL were greater in WKY than in SHR. As a result, the elevation of biochemical EFA deficiency index—20∶3n−9/20∶4n−6 ratio—was greater in WKY than in SHR. In comparison with WKY, the concentrations of liver triacylglycerols and the weights of adipose tissues in SHR were reduced to a greater extent, indicating an active catabolism of triacylglycerols in SHR. This study suggests that the earlier appearance of morphological symptoms of EFA deficiency in SHR was not associated with the reducing n−6 EFA levels or with an elevation of triene/tetraene ratio, but possibly to a reduced supply of n−6 EFA for skin prostaglandin synthesis.
Increased biliary calcium in cholesterol and pigment gallstone disease: The role of altered bile acid composition
Authors: Abedin Mohammad Z. , Strichartz Seth D. , Festekdjian Sarkis , Roslyn Joel J. 
Published: November 2006

AbstractThe present study was undertaken to define the relationship between calcium metabolism and bile acid composition in animal models of diet induced cholesterol and pigment gallstones. Groups of prairie dogs were fed either a control non‐lithogenic chow (N=12), a 1.2% cholesterol enriched chow (N=6, XOL) for two weeks, or a high carbohydrate diet deficient in iron (N=6, CHO‐FeD), or a high carbohydrate diet with normal iron levels (N=6, CHO) for eight weeks. Hepatic (HB) and gallbladder (GB) bile samples were analyzed for total calcium, cholesterol, phospholipids, total bile acids (TBA), and individual bile acid composition.In each of the four groups, TBA concentrations were essentially similar and taurine conjugates accounted for approximately 90% of TBA in HB bile and about 98% in GB bile. In the control group, cholic acid (CA) was the predominant bile acid and comprised 76% of TBA and chenodeoxycholic (CDCA) accounted for about 13% of the total. Feeding a diet rich in cholesterol caused a significant change in the relative concentrations of individual bile acids of hepatic bile—such that CA decreased significantly (p<0.001) while CDCA increased by 300% (p<0.001). The changes in secondary bile acids were insignificant. An identical shift in individual bile acid composition was noted in animals maintained on high carbohydrate diet, irrespective of iron content. Similar changes were observed in the GB in the experimental groups.Calcium concentrations of GB bile with or without gallstone formation showed a positive linear relationship with TBA (y=4.35+0.14X, p<0.001) and taurochenodoxycholic acid (TCDCA) (y=15.04+0.46X, p<0.001), but an inverse relationship with taurocholic acid (TCA) (Y=55.16−0.41X, p<0.008). However, such relationships were absent in hepatic bile. These data indicate that diet‐induced alterations in bile acid composition may modify calcium solubility or GB function, thereby contributing to the increased GB calcium observed during cholesterol and pigment gallstone formation.
Effect of α‐tocopherol on the volatile thermal decomposition products of methyl linoleate hydroperoxides
Authors: Frankel E. N. , Gardner H. W. 
Published: November 2006

Abstractα‐Tocopherol and 1,4‐cyclohexadiene were tested for their effect on the thermal decomposition of methyl linoleate hydroperoxide isomers. The volatiles generated by thermolysis in the injector port of a gas chromatograph at 180°C were analyzed by capillary gas chromatography. In the presence of either α‐tocopherol or 1,4‐cyclohexadiene, which are effective donors of hydrogen by radical abstraction, volatile formation decreased in all tests, and significant shifts were observed in the relative distribution of products in certain hydroperoxide samples. When an isomeric mixture of methyl linoleate hydroperoxides (cis, trans andtrans, trans 9‐ and 13‐hydroperoxides) was decomposed by heat, the presence of α‐tocopherol and 1,4‐cyclohexadiene caused the relative amounts of pentane and methyl octanoate to decrease and hexanal and methyl 9‐oxononanoate to increase. A similar effect of α‐tocopherol was observed on the distribution of volatiles formed from a mixture of thetrans,trans 9‐ and 13‐hydroperoxides. This effect of α‐tocopherol was, however, insignificant with purecis,trans 13‐hydroperoxide of methyl linoleate. The decrease in total volatiles with the hydrogen donor compounds, α‐tocopherol and 1,4‐cyclohexadiene, indicates a suppression of homolytic β‐scission of the hydroperoxides, resulting in a change in relative distribution of volatiles. The increase in hexanal and methyl 9‐oxononanoate at the expense of pentane and methyl octanoate in the presence of hydrogen donor compounds supports the presence of a heat‐catalyzed heterolytic cleavage (also known as Hock cleavage), which seems to mainly affect thetrans,trans isomers of linoleate hydroperoxides.
Trans fatty acids. 3. Fatty acid composition of the brain and other organs in the newborn piglet
Authors: Pettersen Jan , Opstvedt Johannes 
Published: November 2006

AbstractThe effects of dietarytrans fatty acids on tissue fatty acid composition were studied in newborn piglets delivered from sows fed partially hydrogenated fish oil (PHFO) (28%trans) or partially hydrogenated soybean oil (PHSBO) (36%trans) in comparison with lard (0%trans) from 3 wk of age and through gestation in Experiment 1, or fed PHFO or “fully” hydrogenated fish oil (HFO) (19%trans) in comparison with coconut oil (CF) (0%trans) with two levels, 1 and 2.7%, of dietary linoleic acid from conception through gestation in Experiment 2. The piglets were sampled immediately after delivery, without having access to mothers' milk.Incorporation oftrans fatty acids into brain PE (phosphatidylethanolamine) were non‐detectable or very low (less than 0.1%). The incorporation of 18∶1trans into heart‐PE, liver mitochondria‐PE, total plasma lipids and adipose tissue was low, and 20∶1trans was not detected. Dietarytrans fatty acids had no consistent effects on the overall fatty acid composition of the different tissue lipids. It is conclude thattrans fatty acids from PHFO, HFO and PHSBO have no significant effects on the fatty acid accretion in the fetal piglet.