bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of fat‐free, saturated and polyunsaturated fat diets on rat liver and plasma lipids
Authors: Nelson Gary J. , Kelley Darshan S. , Schmidt Perla C. , Serrato Claire M.
Published: November 2006

The liver and plasma lipids and fatty acid composition of rats fed synthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a high carbohydrate, fat‐free diet for 48 hr. They were then divided into three groups and fed for an additional 48 hrs the following: group 1, the fat‐free diet; group 2, a diet containing 44% of calories from corn oil; and group 3, a diet containing 44% calories from completely hydrogenated soybean oil. The total lipid concentration of the liver in the animals on the fat‐free diet was elevated at 72 and 96 hr. The addition of either saturated or unsaturated fat in the diet at 48 hr prevented this accumulation. The total phospholipid and cholesterol concentrations of the liver were relatively uninfluenced by any diet in this study. Plasma total fatty acid concentration was elevated at 72 hr in the animals on a fat‐free diet compared to those fed the stock diet, starved for 48 hr or fed the fat‐containing diets. By 96 hr, however plasma fatty acid concentrations in all groups were similar to those in animals fed only the stock diet. The release of de novo synthesized fatty acids into plasma from the liver was strongly inhibited by dietary fat, either saturated or polyunsaturated. With the fat‐free diet there was a significant increase in the saturated and monounsaturated fatty acids in both liver and plasma. The addition of corn oil to the diet facilitated a reversion of the fatty acid composition in liver and plasma to that found in the animals fed the stock diet ad libitum, but saturated fat did not. No effect of diet on the fatty acid composition of the red cells was observed during the course of this study. Exogenous saturated fatty acids, although similar chemically to the fatty acids synthesized by the liver, may have physiological actions that differ from endogenously synthesized fat.
The effect of mengovirus infection on lipid synthesis in cultured ehrlich ascites tumor cells
Authors: Schimmel Helmut , Traub Peter
Published: November 2006

The concept of generally increased lipid synthesis during the initial 2/3 of picornaviral infectious cycles, held by several authors, needs differentiation. In mengovirus‐infected Ehrlich ascites tumor cells, an increase in the rate of synthesis of phosphatidylcholine could be confirmed, but for phosphatidylethanolamine constant to decreasing rates of synthesis were found. Moreover, phosphatidylinositol was increasingly synthesized in the midst of the infectious cycle. The changes observed might have their functional expression in the proliferation of smooth cytoplasmic membrane systems that provide the structural framework for the replication of picornaviral RNA and virus assembly. The alterations in the labeling patterns of phosphatidylinositol, phosphatidylglycerol and diphosphatidylglycerol late in virus infection point to increased turnover of these compounds, possibly mediated by phospholipase D. The formation of lysophosphatidylcholine (cytolytic effect) and bis(monoacylglyceryl)phosphate in the final phase of the infectious cycle might be correlated with the liberation of lysosomal enzymes and the development of the cytopathic effect.
Oleic acid modulates the partitioning of cholesterol from micellar bile salt solution
Authors: Chijiiwa Kazuo
Published: November 2006

The effects of monounsaturated fatty acid (oleic acid) on cholesterol monomer activity and on the rate of cholesterol influx were studied in vitro. A polyethylene disc method was employed to determine cholesterol monomer activity in constant sodium taurocholate‐cholesterol micellar solution containing different oleic acid concentration levels at pH 5.5, 6.5 and 7.2. In addition, the effect of oleic acid on the rates of cholesterol influx was determined using an everted rat jejunal sac technique.

At pH 5.5, increased oleic acid concentration from 5 to 10 mM resulted in significant decreased apparent cholesterol monomer activity (3.8±0.21 nmol/disc vs 1.0±0.08, P<0.001). At pH 6.5, apparent cholesterol monomer activity was 2.3±0.19 nmol/disc at 5 mM and 0.5±0.09 at 16 mM oleic acid level (P<0.001). Apparent monomer activity of cholesterol in micellar solutions at pH 7.2 used for the influx study at 5 and 15 mM oleic acid concentration level was 1.8±0.14 and 0.7±0.08 nmol/disc, respectively (P<0.001). Thus there was a significant decrease in cholesterol monomer activity by the addition of oleic acid at each pH. The rate of cholesterol influx across the brush border membrane of the rat jejunum at 5 and 15 mM oleic acid concentration level was 3.2±0.31 and 1.5±0.21 nmol/100 mg dry weight tissues/min, respectively (P<0.001).

It is concluded that the addition of oleic acid decreases both monomer activity and the rate of influx of cholesterol from micellar solution. This effect is primarily attributable to the inhibition of the release of cholesterol monomers from the mixed micelle.
Bile lipid secretion in isolated perfused rat liver. A model for metabolic studies
Authors: Henry J. C. , Domingo N. , Chanussot F. , Lafont H. , Hauton J. C. , Cano J. P.
Published: November 2006

Isolated perfused rat liver was used to study the effects of constant taurocholate perfusion, with or without the addition of phosphatidylcholine unilamellar vesicles, upon both the bile salt‐dependent and bile salt‐independent secretion of bile. Taurocholate introduction increased bile flow and normalized the bile lipid secretion by restoring the bile salt‐dependent secretion. At a flow rate of 30 ml/min, the liver was perfused by a single‐pass method. The perfusion medium contained 17.5 μM taurocholate with or without 5.83 μM phosphatidylcholine. In light of a recent quantitative dynamic concept on the interphase partition of lipids, it was calculated that more than99% of the taurocholate reaches the liver as monomers and/or dimers. It was also deduced that the lipids were secreted in bile as small discoidal lipoprotein structures rather than unilamellar lipoproteic vesicles. During the course of the experiments (2 hr), the excellent criteria of viability of this model make it highly suitable for the investigation of hepatic metabolism. Furthermore, the addition of phosphatidylcholine unilamellar vesicles to the perfusate consitutes a potential vector for various liposoluble molecular species.
Activities of liver mitochondrial and peroxisomal fatty acid oxidation enzymes in rats fedtrans fat
Authors: Ide Takashi , Watanabe Midori , Sugano Michihiro , Yamamoto Iwahiko
Published: November 2006

The effect oftrans fat on the activities of liver mitochondrial and peroxisomal fatty acid oxidation enzymes was examined in various strains of rats. When Wistar and Sprague‐Dawley rats were fed for 30 days diets containing either olive oil or partially hydrogenated corn oil as a source ofcis‐ortrans‐octadecenoate, respectively, the activities of various enzymes of mitochondrial and peroxisomal β‐oxidation measured withcis‐ andtrans‐9‐octadecenoic acid as substratese showed little dietary fatdependent change. In Fischer 344 rats, feedingtrans fat for 15 mo increased only moderately various enzymes of β‐oxidation except for carnitine acyltransferase. The rate of mitochondrial ketogenesis and the activity of carnitine acyltransferase measured withtrans‐9‐octadecenoic acid as a substrate were about half those with thecis‐counterpart. Peroxisomes oxidizedtrans‐9‐octadecenoyl‐CoA at a rate comparable to thecis‐counterpart. It was concluded from this study and previous ones that the difference in the geometry of dietary fatty acid had only a marginal effect in modulating the hepatic fatty acid oxidation system, in spite of marked differences in the metabolic behavior ofcis‐andtrans fatty acid in cell‐free preparations and perfused liver.
Effect of lecithin on the release of 5′‐nucleotidase from liver plasma membrane of rat by bile acids
Authors: Nokubo Munetaka
Published: November 2006

Bile acids solubilize proteins from liver plasma membrane both in vivo and in vitro. The ability to solubilize the proteins is dependent on the species of bile acid. In this paper, the effect of phospholipid on the solubilization of a membrane‐bound enzyme by bile acids was investigated in vitro. Taurocholate (TC) and tauroursodeoxycholate (TUDC) solubilized the enzyme, 5′‐nucleotidase, from the liver plasma membrane of the rat in a concentration‐dependent manner, although there was a great difference in their effect; at 40 mM, TC solubilized 55.4% of the original 5′‐nucleotidase activity of the membrane, but TUDC only 5.7%. While lecithin alone had no solubilizing effect, its addition to the bile acids provoked a 10‐fold increase in the solubilizing effect of TUDC, but virtually no change for TC, essentially equalizing the solubilizing effect of the two. Both TC‐rich and TUDC‐rich bile were obtained from rats infused with the respective bile acids via the jugular vein after their endogenous bile acid pool had been depleted. The solubilization effect of these biles was quite similar to the bile acid‐lecithin mixtures. These findings demonstrate that lecithin enhances the ability of the bile acids to solubilize the membrane protein and eliminates the difference in the two bile acid species in their solubilizing ability.
Asymmetric distribution of arachidonic and n−3 polyunsaturated fatty acids in rat liver microsomal membranes under a fat‐free diet
Authors: Iritani Nobuko , Mizoguchi Hisako , Kitaya Misao
Published: November 2006

Rats adapted to a corn oil or a fish oil diet were fed a fat‐free diet, and changes in phospholipid polyunsaturated fatty acids (PUFA) in the inner and outer leaflets of liver microsomal membranes were followed for 18 wk. In rats previously adapted to a corn oil diet, arachidonic acid in phosphatidylcholine and phosphatidylethanolamine in the inner and outer leaflets did not decrease quickly; rather, linoleic acid decreased more than arachidonic acid for the first three weeks of feeding the fat‐free diet. Even at 18 wk, 40–50% of the beginning arachidonic acid levels were still retained. In contrast, in rats previously adapted to a fish oil diet, the n−3 PUFA were quickly decreased by the fat‐free diet to only 10–30% at 18 wk. Due to the appearance and increase of n−9 eicosatrienoic acid in the replacement of the n−3 and n−6 PUFA, total PUFA did not decrease in the inner and outer phosphatidylcholine in either group, but decreased somewhat in the phosphatidylethanolamine due to the insufficient increase of the n−9. On the other hand, the overall degrees of unsaturation in phosphatidylcholine fatty acids were always higher in the outer than in the inner leaflets and were not altered by feeding the fat‐free diet even for 18 wk. Thus, the results appear to reveal the physiological importance of unsaturation ratio of fatty acids and the necessity of arachidonic acid in each membrane leaflet.
A micromethod for the estimation of blood dolichol
Authors: Morris George N. , Pullarkat Raju K.
Published: November 2006

A micromethod for the estimation of dolichol in blood was developed using high performance liquid chromatography. This method can be applied to whole blood or plasma. With detector sensitivity set at 0.005 Absorbance Unit Full Scale, samples as little as 50 μl are sufficient to carry out the determination. Blood samples from the tail vein of inbred strains of C57 BL/6 NNia‐1 mice 3,6, 12 and 24 mo of age were examined. Blood dolichol levels decreased with age from 163.3 ng/ml at 6 mo to 110.1 ng/ml at 24 mo. The major dolichol homologs were C‐85 (10.4%), C‐90 (41.6%), C‐95 (38.0%) and C‐100 (8.1%).
Lymphatic absorption of nonvolatile oxidation products of heated oils in the rat
Authors: Combe N. , Constantin M. J. , Entressangles B.
Published: November 2006

The lymphatic absorption of nonvolatile oxidation products (NVOP) formed during heating of fats was studied. Heated colza or soybean oils or synthetic triglycerides containing a definite aromatic or alicyclic fatty acid were fed to thoracic duct‐cannulated rats. Tritium‐labeled triolein was added to each dietary fat, as an internal standard, in order to calculate the percentage of lymphatic absorption of the ingested NVOP. Results show that 4% of the total polymeric acids, 53% of the total oxidized monomeric acids and 96% of the total cyclic monomeric acids were recovered in the lymphatic lipids. Gas liquid and quantitative thin layer chromatography of these 3 classes indicated that, within a NVOP class, the various constituents did not present the same absorption rate. The lymphatic absorptions of individual oxidized monomers were between 25 and 93%. Concerning the polymer fraction, the lymphatic recoveries were 1% (nonpolar dimers), 6.8% (polar dimers) and 12% (polar oligomers). Aromatic acids were absorbed to a lesser degree (50–60%) than cyclohexenic acids (91–98%).
Antilipidemic activity of 4‐oxo‐functionalized ethyl 6‐chlorochroman‐2‐carboxylate analogs and a related tricyclic lactone in three rat models
Authors: Cavestri R. C. , Minatelli J. A. , Baldwin J. R. , Loh W. , Feller D. R. , Newman H. A. I. , Sober C. L. , Witiak D. T.
Published: November 2006

The synthesis of ethylcis‐6‐chloro‐4‐hydroxychroman‐2‐carboxylate (IV) and 6‐chloro‐4‐hydroxychroman‐2‐carboxylic acid lactone (V) are reported. The antilipidemic properties of these compounds in 3 rat models were compared to the activity obtained for the previously synthesized related analogs ethyl 6‐chlorochroman‐2‐carboxylate (II), ethyl 6‐chlorochromanone‐2‐carboxylate (III) and clofibrate (I). The biologically most interesting analog, ethyl 6‐chlorochroman‐2‐carboxylate (II) like clofibrate (I), was an effective antitriglyceridemic and anticholesterolemic agent in Triton WR‐1339 hyperlipidemic rats, sucrose‐fed hyperlipidemic rats and chow‐fed normolipemic rats. Ethyl 6‐chlorochromanone‐2‐carboxylate (III) was found to be active only after 7 days of administration to sucrosefed rats. In sucrose‐fed, male Sprague‐Dawley rats, the comparative effects of these analogs on various hepatic drug parameters also were carried out. Consistent with previous findings, results obtained with these compounds provide evidence showing that changes in hepatic HMG‐CoA reductase activity bear no relationship to serum cholesterol lowering in the sucrose‐fed model.
The enzymic synthesis of GM1b: rat‐brain CMP‐N‐Acetylneuraminic acid: Asialo‐GM1 sialyltransferase
Authors: Yip M. C. M. , Nguyen N. T.
Published: November 2006

An enzyme which catalyzes the transfer of N‐acetylneuraminic acid (NeuNAc) to a tetrahexosylceramide (asialo‐GM1) in young rat brain is described. The enzymic product is a new monsialoganglioside containing a neuraminidase‐labile neuraminic acid, GM1b. The activity of this sialyltransferase is higher in fetal and young rat brains. The enzyme exhibits a pH optimum of 6.5 in cacodylate buffer. The incorporation of radioactivity into GM1b is stimulated in the presence of asialo‐GM1 and CMP‐NeuNAc and is dependent, on the quantity added. The detergent mixture, Tween 80 and CF54, is required for optimal activity. Recent demonstration of the natural occurrence of GM1b in the free cell types of rat ascites hepatoma cells suggests a functional importance of this CMP‐NeuNAc:asialo‐GM1 sialyltransferase in the in vivo formation of this novel monosialoganglioside.
Fatty acid composition of individual plasma steryl esters in phytosterolemia and xanthomatosis
Authors: Kuksis A. , Myher J. J. , Marai L. , Little J. A. , McArthur R. G. , Roncari D. A. K.
Published: November 2006

The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins. We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis. For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids. The saturated and unsaturated sterols esterified to saturated, monoenoic, dienoic and tetraenoic fatty acids were identified by GLC analysis of the sterol moieties of the corresponding AgNO3‐TLC fractions of the steryl esters. The GLC results were confirmed by reversed phase high performance liquid chromatography combined with mass spectrometry via direct liquid inlet interface. It was found that, in general, each fatty acid was esterified to the same complement of sterols, and that the esterified sterols possessed a composition comparable to that of the free plasma sterols, which was comprised of about 75% cholesterol, 6% campesterol, 4% 22,23‐dihydrobrassicasterol and 15% β‐sitosterol. The fatty acid composition of the steryl esters differed from that of the 2‐position of the plasma phosphatidylcholines, which contained significantly less palmitic and oleic and more linoleic acid. On the basis of these results and a review of the literature it is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin‐cholesterol acyltransferase and synthesis in tissues via the acylCoA‐cholesterol acyltransferase.
cis‐Vaccenic acid in mango pulp lipids
Authors: Shibahara Akira , Yamamoto Kohei , Nakayama Takao , Kajimoto Goro
Published: November 2006

A peak corresponding to a methyl octadecenoate other than oleate has been detected on the capillary gas chromatogram of the methyl esters of mango pulp fatty acids. This octadecenoate was isolated by silica gel and argentation column chromatography, high performance liquid chromatography and argentation thin layer chromatography, and then analyzed by infrared, nuclear magnetic resonance and gas chromatography‐mass spectrometry, chromatographic separations and oxidative degradation. These analytical data proved that the octadecenoic acid wascis‐vaccenic acid (cis‐11‐octadecenoic acid). The concentration of this acid in total octadecenoic acids ranged from 35% to 50% in the pulp of mangoes from Fiji, Mexico, the Philippines and Taiwan.cis‐Vaccenic acid was revealed to be one of the major component fatty acids of non‐polar lipids (mainly triacylglycerols), glycolipids and phospholipids in mango pulp. The glycolipids containedcis‐vaccenic acid (ca. 20%) in higher concentration than oleic acid (ca. 15%). A trace amount ofcis‐vaccenic acid (0.5%) was detected in the total lipids of mango seeds. Profile of fatty acid composition of mango pulp lipids (0.2–0.3 wt% of wet pulp) was characterized by the presence of n−7 acid isomers,cis‐vaccenic acid and palmitoleic acid, and unusual mono‐ and dienoic positional isomers.
Influence of dietary fat on metabolism of (14‐14C)erucic acid in the perfused rat liver. Distribution of metabolites in lipid classes
Authors: Hølmer Gunhild , Rønneberg Ragnhild
Published: November 2006

Two groups of rats were fed diets containing 20% by weight of either partially hydrogenated marine oil supplemented with sunflower seed oil (PHMO) or palm oil (PO) for 8 wk. Using a liver perfusion system, the effect of dietary long chain monoenoic fatty acids on the uptake and metabolism of [14‐14C]erucic acid was studied. The perfusion times were 15 and 60 min, respectively. The two groups showed equal ability for erucic acid uptake in the liver but differed in the channeling of the fatty acids into various metabolic pathways. A higher metabolic turnover of 22∶1 in the PHMO livers relative to the PO livers was demonstrated by an increased recovery of total [14C]labeling in the triglyceride (TG) and phospholipid (PL) fractions, already evident after 15 min of perfusion. The chainshortening capacity was highest in the PHMO group, reflected by a higher [14C]18∶1 incorporation in both TG and PL, and increasing from 15 to 60 min of perfusion. The amount of [14C]18∶1 found in PL and TG after 60 min of perfusion of livers from rats fed PO corresponded to that shown for the PHMO group after 15 min. The PL demonstrated a discrimination against 22∶1 compared to TG, and, when available, 18∶1 was highly preferred for PL‐synthesis.

The total fatty acid distribution in the TG, as determined by gas liquid chromatography (GLC), reflected the composition of the dietary fats. In the total liver PL, 22∶1 and 20∶1 were present in negligible amounts, although the PHMO diet contained 12–13% of both 22∶1 and 20∶1. In the free fatty acid fraction (FFA), the major part of the radioactivity (≈80%) was [14‐14C]erucic acid, and only small amounts of [14C]18∶1(<2%) were presents, even after 60 min of perfusion. The shortened‐chain 18∶1 was readily removed from the FFA pool and preferentially used for lipid esterification.
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

Delta‐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

High 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

Sterol 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

Soybean 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

The 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

Recently, 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

[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

A 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

Mouse 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

The 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

The 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

Fecal 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

Some 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

Paris 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

Weanling 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

The 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

α‐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

The 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.
The effect of dietary n−6 and n−3 polyunsaturated fatty acids on blood pressure and tissue fatty acid composition in spontaneously hypertensive rats
Authors: Watanabe Yoshiyasu , Huang Yung‐Sheng , Simmons Valerie A. , Horrobin D. F.
Published: November 2006

Effects of dietary n−6 and n−3 fatty acids (FAs) on blood pressure (BP) and tissue phospholipid (PL) FA composition in spontaneously hypertensive (SHR) and normotensive Wistar‐Kyoto (WKY) rats were compared. Male weanling SHR and WKY were fed a fat‐free semisynthetic diet supplemented with 10% (w/w) fats containing (a) 78% 18∶2n−6 (LA‐rich), (b) 20% LA and 55% 18∶3n−3 (LN‐rich), or (c) 11% LA and 3% LN (CON) for seven weeks. Dietary fats did not affect the BP elevation, but significantly altered the FA composition of brain, adrenal gland, renal medulla and cortex PL in SHR. The LA‐rich diet increased n−6 FA while it reduced n−3 FA levels. The levels of 20∶4n−6 were not significantly different between animals fed the LA‐rich and the CON diets. LN‐rich diet increased the levels of n−3 FAs, while it reduced those of n−6 FAs. However, the extent of change was significantly less in SHR than in WKY. In all dietary groups, SHR, as compared to WKY, had a relatively higher level of the 2 series prostaglandin (PG) precursor, 20∶4n−6, and a relatively lower level of the 1 and 3 series PG precursors, 20∶3n−6 and 20∶5n−3. The possibility that the unbalanced eicosanoid FA precursor levels might contribute to the development of hypertension in this animal model is discussed.
A modification of the thiobarbituric acid reaction
Authors: Bidder T. George , Sipka Bona M.
Published: November 2006

A simple modification of the thiobarbituric acid reaction, which removes nonspecific chromogenic reaction products, involves incubation at room temperature for 16–20 hr and a column chromatographic step. The chromogen‐concentrating capacity of the latter step is useful for determination of low concentrations of thiobarbituric acid‐reactive materials in biological preparations.
Antioxidant activity of β‐carotene‐related carotenoids in solution
Authors: Terao J.
Published: November 2006

The effect of the antioxidant activity of β‐carotene and related carotenoids on the free radical‐oxidation of methyl linoleate in solution was examined by measuring the production of methyl linoleate hydroperoxides. Canthaxanthin and astaxanthin which possess oxo groups at the 4 and 4′‐positions in the β‐inonone ring retarded the hydroperoxide formation more efficiently than β‐carotene and zeaxanthin which possess no oxo groups. The rates of autocatalytic oxidation of canthaxanthin and astaxanthin were also slower than those of β‐carotene and zeaxanthin. These results suggest that canthaxanthin and astaxanthin are more effective antioxidants than β‐carotene by stabilizing the trapped radicals.
On the isolation of the new fatty acid 6,11‐eicosadienoic (20∶2) and related 6,11‐dienoic acids from the spongeEuryspongia rosea
Authors: Carballeira Nestor M. , Maldonado Maria E.
Published: November 2006

The phospholipid fatty acids from the spongeEuryspongia rosea were studied revealing the presence of the new 6,11‐eicosadienoic (20∶2) acid and the rare 6,11‐octadecadienoic acid (18∶2). The isolation of these 6,11‐dienoic acids reveals the presence of new biosynthetic possibilities in sponges and suggests the presence of an active Δ6 desaturase inE. rosea. Other acids isolated fromE. rosea include 12‐eicosenoic (20∶1) and 17‐tetracosenoic acid (24∶1). The major phospholipids encountered in the sponge were phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylcholine (PC).