bluuebunny/crossref_metadata_2025 huggingface dataset:
The differential effect of eicosapentaenoic acid and oleic acid on lipid synthesis and VLDL secretion in rabbit hepatocytes
Authors: Benner Kent G. , Sasaki Anna , Gowen Dale R. , Weaver Alice , Connor William E.
Published: November 2006

The suppression of plasma very low density lipoprotein (VLDL) triglyceride levels by dietary fish oils rich in polyunsaturated n−3 fatty acids has been attributed to decreased hepatic VLDL secretion. To investigate the effect of n−3 fatty acids on lipid metabolism and VLDL secretion in a tissue culture system, we incubated rabbit hepatocytes with oleic acid and eicosapentaenoic acid (EPA) and examined [3H]glycerol and [14C]fatty acid incorporation into hepatocyte triglyceride and phospholipid and into media VLDL. Glycerol incorporation studies showed that EPA failed to stimulate VLDL triglyceride secretion from hepatocytes as occurred with oleic acid (P<0.05). Oleic acid preferentially enhanced hepatocyte triglyceride synthesis while EPA stimulated significantly phospholipid synthesis (P<0.01). Varying the relative concentrations of oleic acid and EPA at a constant total fatty acid concentration corroborated preferential triglyceride synthesis from oleic acid. Synthesis shifted predominantly to phospholipids with increasing concentrations of EPA and lower levels of oleic acid. Incorporation of the [14C]fatty acids (800 μM) followed similar patterns: 87% of [14C]oleic acid was incorporated into hepatocyte triglyceride and 44% of [14C]EPA was assimilated in hepatocyte phospholipid (p<0.001). Fatty acids at trace concentrations (53 nM) showed a more divergent pattern of lipid incorporation: 60% of [14C]oleic acid was incorporated into triglyceride while 91% of [14CEPA was incorporated into phospholipid (p<0.001). We conclude that in primary rabbit hepatocyte culture, which appears to be a useful model to study lipid metabolism and VLDL secretion, EPA is avidly incorporated into phospholipid while oleic acid predominantly becomes esterified in triglyceride. In addition, EPA, unlike oleic acid, fails to stimulate hepatocyte VLDL secretion. These divergent effects on hepatocyte lipid metabolism are, at least in part, likely to be responsible for fish oil induced suppression of plasma triglycerides.
Reduction in microalbuminuria in diabetics by eicosapentaenoic acid ethyl ester
Authors: Hamazaki Tomohito , Takazakura Eisuke , Osawa Kenzo , Urakaze Masaharu , Yano Saburo
Published: November 2006

Eicosapentaenoic acid (EPA) ethyl ester (1.8 g/d) was administered to 16 diabetic patients (5 insulin‐dependent and 11 noninsulin‐dependent diabetics) for 6 mon. EPA in total plasma fatty acids increased from 4.0±2.4 mol% (mean±SD) to 7.5±3.1 mol% (p<0.001). Albumin excretion, measured with spot urine, was significantly reduced from 65 to 36 mg/g creatinine (geometric means, p<0.001). Fasting blood sugar levels, glycohemoglobin, body weight and blood pressure did not change significantly during the study. There were also no significant changes in serum levels of creatinine, urea nitrogen, total cholesterol and triglycerides. Although no overt hemorrhage was observed in the patients, hematocrit was reduced from 42.6±2.8% to 41.0±3.9% (p<0.02). Ten other similar diabetic patients (4 insulin‐dependent and 6 non‐insulin‐dependent diabetics) were followed as a reference group, not concomitantly, for 6 mon with neither EPA ethyl ester nor placebo. The parameters mentioned above were not changed significantly in this group during 6 mon. EPA administration might retard the appearance of overt diabetic nephropathy.
On the effect of peroxisomal β‐oxidation and carnitine palmitoyltransferase activity by eicosapentaenoic acid in liver and heart from rats
Authors: Aarsland Asle , Lundquist Morten , Børretsen Bernt , Berge Rolf K.
Published: November 2006

Repeated administration of highly purified eicosapentaenoic acid (as ethyl ester) resulted in a decrease in plasma triglycerides and high density lipoprotein (HDL) cholesterol. This was accompanied by a stimulation in the activities of carnitine palmitoyltransferase, fatty acyl‐CoA oxidase and peroxisomal β‐oxidation in the liver. The results suggest that the triglyceride‐lowering effect observed with eicosapentaenoic acid may be due to a reduced supply of fatty acids for hepatic triglyceride synthesis because of increased fatty acid oxidation. Eicosapentaenoic acid feeding marginally affected the triglyceride content of heart and mitochondrial and peroxisomal enzyme activities.
Intestinal absorption of retinol and retinyl palmitate in the rat. Effects of tetrahydrolipstatin
Authors: Fernandez Ester , Borgström Bengt
Published: November 2006

The aim of the present study was to characterize the intestinal absorption of retinol and retinyl palmitate in thoracic duct and bile duct fistulated rats and to investigate the effect of a simultaneously administered lipase inhibitor, tetrahydrolipstatin (THL). Absorption was determined as lymphatic recovery over a 24‐hr period, including an initial 12‐hr continuous intraduodenal infusion of either [11,12‐3H]retinol or [11,12‐3H]retinyl palmitate given in emulsified glyceryl trioleate or in mixed micellar solution of monoolein and oleic acid. From micellar dispersion, labeled retinol and retinyl palmitate were recovered in the lymph to 50–60% and both to the same extent. Administered in emulsified form, labeled retinol from fed retinyl palmitate was recovered to 47%, but retinol from fed retinol to only 18%. THL (10−4 M) in the infusate had no significant effect on the recovery of14C‐labeled oleic acid. The recovery of label from emulsified glyceryl tri[1‐14C]oleate was significantly decreased at this concentration of THL (76.5% vs 19.6% recovery). When administered in emulsified form, retinol absorption was not significantly affected by THL at 10−4 M, while retinyl palmitate absorption was very significantly decreased (5.0% compared to 47.8%). In the presence of THL, retinol absorption from retinyl palmitate in micellar solution was decreased (from 58% to 17%). Most of the retinol in the lymph extracts (72.2 to 91.3) was present as retinyl ester, regardless of the chemical and physical form of administration. Furthermore, THL did not induce any change in this pattern.
Liver phosphatidylcholine hydroperoxidation provoked by ethionine‐containing choline‐deficient diet in mice
Authors: Yoshida Lucia Satiko , Miyazawa Teruo , Fujimoto Kenshiro , Kaneda Takashi
Published: November 2006

It is shown that peroxidation of phosphatidylcholine (PC) is enhanced in liver of mice fed a hepatocarcinogenic choline‐deficient diet containing 0.1% w/w ethionine. Mice were divided into 4 groups and fed for 3 weeks one of the following diets: choline‐supplemented; choline‐supplemented containing ethionine; choline‐deficient; and choline‐deficient containing ethionine. Phosphatidylcholine hydroperoxide (PCOOH) of liver lipids was measured by high performance liquid chromatography using a chemiluminescence detector. Mice fed a choline‐deficient diet containing ethionine showed 6‐fold higher PCOOH levels than the choline‐supplemented control mice: the PCOOH/PC molar ratios of liver lipids were 32.3×10−5 and 5.6×10−5, respectively. In addition to this remarkable degree of lipid peroxidation in liver of mice fed the choline‐deficient diet containing ethionine, we also observed a significant liver fatty infiltration, a decrease in plasma and liver α‐tocopherol, and an increase in liver injury‐indicative enzyme activities. Also, marker enzymes for hepatocarcinogenesis, glucose‐6‐phosphatase and γ‐glutamyl transpeptidase were affected. These data suggest that enhanced hydroperoxidation of phosphatidylcholine may participate in hepatocarcinogenesis provoked by choline deficiency in the presence of ethionine.
Advantages of total lipid hydrogenation prior to lipid class determination on chromarods‐SIII
Authors: Shantha N. C. , Ackman R. G.
Published: November 2006

The changes in detector responses of lipid classes for standards and natural lipid samples after hydrogenation were investigated with the TLC/FID Iatroscan system using Chromarods‐SIII (Newman‐Howells Associates, Ltd., Midwales, U.K.). Samples included lipids of human plasma and erythrocytes, egg lipids, a fish oil concentrate and triacylglycerols of sea scallop, as well as standards (mono‐, di‐ and triacylglycerols, phosphatidylcholines, phosphatidylethanolamines, lysophosphatidylcholines, free fatty acid, and sterol). The duration of hydrogenation was increased from 45 min to 90 min for some samples to bring hydrogenation to completion. Since the detector response of a lipid class is known to depend on its relative position on the Chromarod, different solvent systems which would vary the migration rate were investigated. The increases in response after hydrogenation, given as relative percent increase (RI), were significant for all compounds examined (p<0.05), and ranged from 7 to 45%. Among the triacylglycerols, the fish oil and the sea scallop triacylglycerols with wide ranges of fatty acid composition had the highest RI while the other lipid classes did not differ from each other. Differences in the solvent systems did not affect the RI except for fish oil triacylglycerols. The precision of peak area measurements was usually better after hydrogenation. The combination of greater sample stability, greater response, improved resolution, and simpler choice of standards make hydrogenation a significant advance in TLC/FID quantification.
Serum apolipoproteins B and A‐I and naturally occurring fatty liver in dairy cows
Authors: Marcos Edgardo , Mazur Andrzej , Cardot Philippe , Rayssiguier Yves
Published: November 2006

Serum lipids and apolipoprotein (apo) B and A‐I concentrations were determined in 164 dairy cows which had undergone liver biopsy in early lactation. The animals were divided into groups according to fatty liver severity on the basis of hepatic triglyceride content. The serum free fatty acid (FFA) concentration was higher in cows that developed fatty livers than in normal cows, and it correlated highly with liver triglycerides. Serum total cholesterol and triglyceride levels did not correlate with hepatic triglycerides. Both apo B and apo A‐I levels were significantly decreased in fatty liver cows. In particular, apo B levels showed a strongly negative correlation with liver triglycerides. The present results suggest that hepatic apolipoprotein synthesis is impeded in fatty liver cows.
Inevitable generation of primary alcohols during reduction of oxidized lipids with sodium borohydride
Authors: Nakamura Takashi , Maeda Hiroyuki , Takahashi Yoshino , Hama Yoichiro
Published: November 2006

This report deals with the fluorometric determination of fatty alcohols generated by the reduction of the ester linkage of lipids with NaBH4, and with the limitations of the reduction method for assaying oxidized lipids. Optimum conditions for the fluorometric analysis of primary and secondary alcohols using 1‐anthroyl nitrile were obtained. After reduction with NaBH4 in MeOH or in MeOH/benzene (8∶2, v/v), the formation of 1‐hexadecanol from a variety of palmitic acid esters was measured fluorometrically by reverse‐phase high‐performance liquid chromatography (HPLC): From glycerides and methyl palmitate, 1–3% (w/w) 1‐hexadecanol was produced and a trace was produced from cholesteryl palmitate (10 min, 21°C). 1‐Hexadecanol was never generated from palmitic acid. Although considerable improvement occurred with the choice of the solvent for the NaBH4 reduction, the generation of primary alcohols from ester lipids usually seems inevitable.
Lipid composition of the pineal organ from rainbow trout (Oncorhynchus mykiss)
Authors: Henderson R. J. , Bell M. V. , Park M. T. , Sargent J. R. , Falcon J.
Published: November 2006

The lipid composition of the pineal organ from the rainbow trout (Oncorhynchus mykiss) was determined to establish whether the involvement of this organ in the control of circadian rhythms is reflected by specific adaptations of lipid composition. Lipid comprised 4.9% of the tissue wet weight and triacylglycerols were the major lipid class present (47% of total lipid). Phosphatidylcholine (PC) was the principal polar lipid, and smaller proportions of other phospholipids and cholesterol were also present. Plasmalogens contributed 11% of the ethanolamine glycerophospholipids (EGP). No cerebrosides were detected. The fatty acid composition of triacylglycerols was generally similar to that of total lipids in which saturated, monounsaturated and polyunsaturated fatty acids (PUFA) were present in almost equal proportions. Each of the polar lipid classes had a specific fatty acid composition. With the exception of phosphatidylinositol (PI), in which 20∶4n−6 comprised 27.4% of the total fatty acids, 22∶6n−3 was the principal PUFA in all lipid classes. The proportion of 20∶5n−3 never exceeded 6.0% of the fatty acids in any lipid class. The predominant molecular species of PC were 16∶0/22∶6n−3 and 16∶0/18∶1, which accounted for 33.2 and 28.5%, respectively, of the total molecular species of this phospholipid. Phosphatidylethanolamine (PE) contained the highest level of di‐22∶6n−3 (13.0%) of any phospholipid. There was also 4.9% of this molecular species in phosphatidylserine (PS) and 4.1% in PC. In PE, the species 16∶0/22∶6, 18∶1/22∶6 and 18∶0/22∶6 totalled 45.1%, while in PS 18∶0/22∶6 accounted for 43.9% of the total molecular species. The most abundant molecular species of PI was 18∶0/20∶4n−6 (37.8%). The lipid composition of the pineal organ of trout, and particularly the molecular species composition of PI, is more similar to the composition of the retina than that of the brain.
Comparison of body weight and adipose tissue in male C57BI/6J mice fed diets with and withouttrans fatty acids
Authors: Atal Subodh , Zamowski Mary Jane , Cushman Samuel W. , Sampugna Joseph
Published: November 2006

The effect of a diet containingtrans‐fatty acids (tFA) on the fatty acid composition and fat accumulation in adipose tissue was investigated in mice. Male C57BI/6J mice were fed Control or Trans Diets that were similar, except that 50% of the 18∶1, which was allcis in the Control Diet, was replaced bytFA in the Trans Diet. At selected ages, body weight, epididymal fat pad weight, perirenal fat yield, adipose tissue cellularity and fatty acid composition were examined. Over the time period studied (2–24 mon), the proportion of 18∶0 and 16∶0 tended to decrease whilecis‐18∶1 levels increased. Compared to the Control Diet, the Trans Diet resulted in adipose tissue lipids with higher percentages of 14∶0 and 18∶2n−6 and lower percentages ofcis‐18∶1 and 20∶4n−6. In polar lipids,tFA replaced saturated fatty acids, whereastFA replacedcis‐18∶1 in the nonpolar lipids. Body weights at 16 and 24 mon of age and epididymal fat pad weights at 8–24 mon of age were lower in mice fed the Trans Diet as compared to those fed the Control Diet. At the ages studied, the Trans Diet also resulted in lower values for perirenal fat weights, triacylglycerol to polar lipid ratios, and adipose cell size. The data suggest that chronic consumption oftFA affects lipid metabolism and results in decreased fat accumulation in murine adipose tissue.
Liver Δ5 and Δ6 desaturase activity differs among laboratory rat strains
Authors: de Antueno Roberto J. , Elliot Michele , Horrobin David F.
Published: November 2006

This study was designed to examine the variations among rat strains in hepatic fatty acid desaturase activities and to determine the correlations between the activities of these enzymes and the levels of each microsomal fatty acid. Wistar rats from two different sources as well as Long‐Evans and Sprague‐Dawley rats were selected to assess, under standard and identical experimental conditions, the liver Δ5 and Δ6 desaturase activities. Both desaturase activities were significantly reduced by 56% in Sprague‐Dawley rats when compared to BB‐Wistar control rats, whereas intermediate reduced values were detected in Wistar (CR) and Long‐Evans strains. The activities of Δ5 and Δ6 desaturases were significantly and positively correlated with each other. However, no significant correlations were detected between either Δ5 or Δ6 desaturase activities and levels of any of their fatty acid substrates or any other of the major microsomal fatty acids. Fatty acid composition of microsomal total lipids showed strain dependency. A positive correlation was detected between the microsomal levels of the two major final products of both desaturases, namely 20∶4n−6 and 22∶6n−3. In general, the sum of n−3 or n−6 fatty acids but not the ratio of one to the other, varied among rat strains. The study demonstrated that Δ6 and Δ5 desaturase activities are strain‐related. The data also suggested that (i) the desaturation activity should be measured and not predicted from the fatty acid composition and (ii) different rat strains should be used for lipid metabolic studies before conclusions are drawn for rats in general.
Diets rich in lean beef increase arachidonic acid and long‐chain ω3 polyunsaturated fatty acid levels in plasma phospholipids
Authors: Sinclair Andrew J. , Johnson Leeann , O'Dea Kerin , Holman Ralph T.
Published: November 2006

Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20∶4ω6) content in people in Westernized societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long‐chain polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long‐chain PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long‐chain PUFA in plasma phospholipids (PL). First, we examined the effect of grilling (5–15 min) and frying (10 min) different cuts of fat‐trimmed lean beef on the long‐chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight) for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very low‐fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20∶3ω6), 20∶4ω6, eicosapentaenoic acid (20∶5ω3), docosapentaenoic acid (22∶5ω3) and docosahexaenoic acid (22∶6ω3). Grilling for 10–15 min, but not frying, of the fat‐trimmed lean beef resulted in 20–30% losses of the 20 and 22 carbon PUFA. The consumption of the lean beef during the first two‐week period, when there was a very low level of dietary fat, was associated with significant increases in the proportion and concentration of 20∶3ω6, 20∶4ω6, 20∶5ω3 and 22∶5ω3 in the plasma PL and a significant decrease in the proportion and content of 18∶2ω6. The addition of beef fat or olive oil to the diets containing lean beef did not alter the plasma PL fatty acid profile compared with the very low‐fat diet, whereas the addition of safflower oil maintained the significant increases in 20∶4ω6 and 22∶5ω3 but led to decreases in 18∶3ω3 and 20∶5ω3 compared with the very lowfat diet. The results showed that diets rich in lean beef increased the 20∶3ω6, 20∶4ω6 and the long‐chain ω3 PUFA levels in the plasma PL. A high level of linoleic acid in diets rich in lean beef prevented the rise in the plasma level of 20∶3ω6 and 20∶5ω3, two fatty acids known to antagonize the effects of 20∶4ω6 on platelet aggregation.
Effects of dietary oils and methyl ethyl ketone peroxide onin vivo lipid peroxidation and antioxidants in rat heart and liver
Authors: Skúladóttir Gudrún V. , Shi‐Hua Du , Brodie Ann E. , Reed Donald J. , Wander Rosemary C.
Published: November 2006

Weanling male Sprague‐Dawley rats were fed diets for four weeks which differed in their content of n−6 (corn oil; CO) and n−3 fatty acids (fish oil; FO), but were similar in their content of saturated and monounsaturated fatty acids and vitamin E. At the end of the four‐week feeding period, each dietary group was subdivided into two groups. One group received a single placebo injection of α‐tocopherol‐stripped corn oil (TSCO); the other group received a single injection of the free radical generator, methyl ethyl ketone peroxide (MEKP), in TSCO. Twenty‐four hours after injection, the effect of dietary oil and MEKP treatment on endogenous lipid peroxide (LPO) production (measured as methylene blue formed by the “Determiner LPO” assay), glutathione (GSH) and vitamin E content, and fatty acid composition of phosphatidylcholine and phosphatidylethanolamine in heart and liver from unfasted animals were measured. FO‐fed rats had significantly heavier hearts and livers, increased levels of n−3 fatty acids in membrane phospholipids, and higher liver LPO levels than CO‐fed rats. MEKP treatment resulted in significantly lower body weights and liver GSH levels. The data indicate that dietary n−3 fatty acids increase lipid peroxidation in liver somewhat more than in heart. The study also demonstrates that the effect of induced oxidative stress due to a single dose of MEKP on lipid peroxide formation and antioxidant status in tissues from unfasted animals was independent of the dietary oils.
A rapid method for the preparation of ganglioside Glac2 (GD3)
Authors: Jennemann Richard , Wiegandt Herbert
Published: November 2006

A method is described for the preparation of ganglioside Glac2 [(II3(NeuAc)2‐LacCer, GD3] from cream of bovine milk using liquid‐phase extraction with methanol or ethanol followed by anion exchange chromatography. The method is rapid and inexpensive; 1 kg cream, centrifuged from 14–15 L of bovine milk, yields approximately 70 mg of pure ganglioside Glac2. The sialic acid constituent of ganglioside Glac2 isolated from bovine milk cream consists solely of theN‐acetylneuraminic acid derivative. The major components of its ceramide consist of octadecasphing‐4‐enine and the 22∶0 (behenic acid) and 23∶0 fatty acids.
Cytoprotective effect of tocopherols in hepatocytes cultured with polyunsaturated fatty acids
Authors: Mikkelsen Lone , Hansen Harald S. , Grunnet Niels , Dich John
Published: November 2006

When highly unsaturated fatty acids are added to cell cultures, it can become important to include antioxidants in the culture medium to prevent cytotoxic peroxidation. To find an optimal antioxidant for this purpose, the effect of 50 μM α‐tocopherol, γ‐tocopherol, α‐tocopheryl acetate, α‐tocopheryl acid succinate, or α‐tocopheryl phosphate, or of 1 μMN,N′‐diphenyl‐1,4‐phenylenediamine, was investigated with respect to the agent's ability to prevent lactate dehydrogenase leakage in long‐term rat hepatocyte cultures supplemented with 0.5 mM highly unsaturated fatty acids. Formation of thiobarbituric acid reactive substances in the cultures was also measured. α‐Tocopheryl acid succinate was found to be the most effective cytoprotective compound, followed byN,N′‐diphenyl‐1,4‐phenylenediamine, α‐tocopherol, γ‐tocopherol and α‐tocopheryl acetate, and α‐tocopheryl phosphate was without effect.
Thermal adaptation affects the fatty acid composition of plasma phospholipids in trout
Authors: Wallaert Chartotte , Babin Patrick J.
Published: November 2006

The adaptive changes in the fatty acid (FA) composition of plasma phospholipids (PL) in response to alterations in environmental water temperature were investigated in juvenile rainbow trout (Oncorhynchus mykiss). The changes observed during thermal adaptation from 22°C in summer to 8°C in winter were reproduced by laboratory cold acclimation (CA) at 6°C of 22°C‐summer‐acclimated animals. In cold‐acclimated and winter‐acclimated trout, the increase in the unsaturation of PL fatty acids was mainly due to an enrichment of approximately 7% in the total weight percentage of 22∶6n−3, while a concomitant significant decrease in the levels of 18∶0 and of the monoenoic n−9 FA was observed. A time course study revealed that the changes in PL fatty acids became significant after 10 d of CA and were complete after one month. These changes in the composition of the fatty acyl chains of plasma total PL indicate that the FA composition of plasma lipoprotein PL does not remain constant during thermal adaptation. This would suggest that plasma lipoproteins provide a rapid systemic supply of lipids containing more or less unsaturated FA during thermal adaptation of poikilothermic animals.
Plasma lipoproteins and liver lipids in two breeds of geese with different susceptibility to hepatic steatosis: Changes induced by development and force‐feeding
Authors: Hermier Dominique , Saadoun Ali , Salichon Marie‐Rose , Sellier Nadine , Rousselot‐Paillet Daniel , Chapman M. John
Published: November 2006

Susceptibility to fatty liver in the force‐fed goose is partly under genetic control. However, the mechanisms leading to liver steatosis in this avian model are poorly understood, but may involve perturbation in hepatic lipoprotein synthesis. Plasma lipoproteins were fractionated by density gradient ultracentrifugation from plasma of geese differing in their susceptibility to liver steatosis (Landes breed, highly susceptible; Rhine breed, partly resistant). The concentrations and chemical compositions of the major lipoprotein classes (VLDL, IDL, LDL and HDL) were characterized at 8, 22 and 27 wk of age and compared to the lipid composition of the corresponding liver. In non‐force‐fed geese, the lipoprotein profile was typical of birds, with high‐density lipoprotein (HDL) predominating (4–5 g/L). However, at 22 and 27 wk of age, very low‐density lipoprotein (VLDL) levels were significantly lower in Landes geese suggesting that this breed may possess a lower ability to export liver lipids, which would explain its susceptibility to liver steatosis when overfed. The livers of force‐fed geese were specifically enriched in triglyceride, and to a lesser extent, in cholesteryl esters and non‐esterified fatty acids as compared to those of control geese of the same age (27 wk). This accumulation of lipids was more pronounced in the Landes breed and was responsible for the higher liver weight in that breed. In both breeds, liver steatosis was accompanied by an increase in plasma levels of HDL (11 g/L), whereas low‐density lipoproteins were essentially absent. An increase in VLDL plasma levels occurred in the Landes breed only (2.51 g/Lvs 1.85 g/L in the Rhine breed), and was positively correlated with liver weight. However, VLDL in force‐fed geese in both breeds were deficient in triglyceride (28–29% by wt) but enriched in cholesterol (41% by wt). These results indicate that a defect in the incorporation of triglyceride into nascent hepatic VLDL may result in liver steatosis in this species.
Protective effect of vitamin E on linoleic acid hydroperoxide‐induced injury to human endothelial cells
Authors: Kaneko Takao , Nakano Shun‐ichiro , Matsuo Mitsuyoshi
Published: November 2006

The protective effects of vitamin E (α‐tocopherol) and its model compounds, which act as antioxidants, on linoleic acid hydroperoxide‐induced injury to human umbilical vein endothelial cells were examined. When incubated at 50 μM with endothelial cells at 37°C for 24 hr, α‐tocopherol protected the cells from injury, and 2,2,5,7,8‐pentamethylchroman‐6‐ol showed a similar protective effect. Trolox C, a water‐soluble vitamin E model compound, had no protective effect. Tocol, a poor antioxidant, proved toxic. During preincubation, α‐tocopherol was incorporated into the cells at 16.6 nmol/ mg protein, while the pentamethylchromanol was incorporated at 0.5 nmol/mg protein; Trolox C was not incorporated at all. The results suggest that agents having both high antioxidant activity and lipophilicity can protect endothelial cells from linoleic acid hydroperoxide‐induced injury.
Age‐related changes in the metabolism of cholesterol in rat liver microsomes
Authors: Stahlberg Dagny , Angelin Bo , Einarsson Kurt
Published: November 2006

The effects of aging on the hepatic metabolism of cholesterol were studied in 1‐, 6‐ and 24‐month‐old male Sprague‐Dawley rats. Microsomal 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activity, which regulates cholesterol biosynthesis, decreased from 835±144 (SEM) pmol/min/mg protein in the youngest group to 219±34 and 205±53 pmol/min/mg protein (p<0.001) in the 6‐ and 24‐month‐old groups, respectively. Cholesterol 7α‐hydroxylase activity, which governs bile acid synthesis, was gradually reduced from 70±14 pmol/min/mg protein in the 1‐month‐old group to 32±7 and 16±3 pmol/min/mg protein (p<0.05) in the 6‐ and 24‐month‐old groups, respectively. Acyl coenzyme A:cholesterol acyltransferase activity, which catalyzes the esterification of cholesterol, averaged 431±47 and 452 ±48 pmol/min/mg protein in the 1‐ and 6‐month‐old groups, respectively, and was increased to 585±55 pmol/min/mg protein (p<0.05) in the 24‐month‐old group. The level of total cholesterol showed an age‐related increase from 1.56±0.16 mg/g liver in the 1‐month‐old group to 1.70±0.15 and 2.20±0.19 mg/g liver (p<0.05) in the 6‐ and 24‐month‐old groups, respectively. The increase was mainly caused by an accumulation of esterified cholesterol. We conclude that a marked decrease in HMG‐CoA reductase occurs between 1 and 6 months of age; thereafter the enzyme activity stays unchanged. The activity of cholesterol 7α‐hydroxylase decreases progressively and drastically with age, whereas the capacity for esterifying cholesterol increases slightly. We speculate that the reduced conversion of cholesterol to bile acids may be one explanation of the age‐related increase of plasma cholesterol seen in rats.
ω3 Fatty acids increase spontaneous release of cytosolic components from tumor cells
Authors: Jenski Laura J. , Sturdevant Laura Kathleen , Ehringer William D. , Stillwell William
Published: November 2006

Mice fed menhaden (fish) oil or coconut oil‐rich diets were inoculated intraperitoneally with a rapidly growing leukemia, T27A. After one week, the tumor cells were harvested, and51Cr was used to label intracellular molecules. Spontaneous release of51Cr was used as a measure of plasma membrane permeability. Compared to cells from mice fed coconut oil (rich in saturated fatty acids), tumor cells from mice fed menhaden oil (rich in long chain polyunsaturated ω3 fatty acids) showed an increased level of spontaneous51Cr release, which was exacerbated by increased temperature and reduced by extracellular protein. At physiological salt concentrations, the releated51Cr was detected in particles of ∼2700 daltons. Enhanced permeability correlated with the incorporation of dietary (fish oil) ω3 polyunsaturated fatty acids docosahexaenoic and eicosapentaenoic acid into the tumor cells. The results demonstrate that ω3 fatty acids are incorporated into cellular constituents of tumor cells and change properties associated with the plasma membrane. This result suggests that dietary manipulation may be used to enhance tumor cell permeability and contribute to tumor eradication.
Do rat kidney cortex microsomes possess the enzymatic machinery to desaturate and chain elongate fatty acyl‐CoA derivatives?
Authors: Suneja Sanoj K. , Nagi Mahmoud N. , Cook Lynda , Osei Peter , Cinti Dominick L.
Published: November 2006

Rat kidney cortex microsomal preparations were unable to catalyze Δ9, Δ6, and Δ5 desaturation of stearoylcoenzyme A (CoA), linoleoyl‐CoA and dihomo‐γ‐linolenoyl‐CoA, respectively. The kidney cortex microsomal fraction, however, did catalyze the malonyl‐CoA dependent fatty acyl‐CoA elongation. The biochemical properties of palmitoyl‐CoA elongation were studied as a function of protein concentration, time, reduced nicotinamide adenine dinucleotide phosphate (NADPH), malonyl‐CoA and substrate concentrations; of the substrates investigated, Δ6.9.12–18∶3 was the most active. Unlike what was observed in the hepatic system, a high‐carbohydrate, fat‐free diet did not induced kidney fatty acid chain elongation. All intermediate kidney cortex microsomal reactions,i.e., β‐ketoacyl‐CoA reductase, β‐hydroxyacyl‐CoA dehydrase andtrans‐2‐enoyl‐CoA reductase activities, were significantly higher (greater than one order of magnitude) than the condensing enzyme activity, suggesting that the rate‐limiting step in total elongation is the initial condensation reaction. Contrary to other reports, the results suggest that the kidney cannot synthesize arachidonic acid needed for eicosanoid production.
Effect of 4,7,10,13,16,19‐docosahexaenoic acid on triglyceride accumulation and secretion in rat hepatocytes in culture
Authors: Martin L. J. , Reaidi G. B. , Gavino G. R. , Gavino V. C.
Published: November 2006

We have investigated the effect of oleic (18∶1) and 4,7,10,13,16,19‐docosahexaenoic (22∶6ω3) acids on triglyceride (TG) accumulation, secretion and reuptake in rat hepatocytes in culture. We also calculated the percentage of total TG, TG‐esterified 18∶1 and TG‐esterified 22∶6ω3 that were secreted relative to the total accumulation (intra+extracellular TG). Both fatty acids were incorporated mainly in the intracellular TG fraction. Treatment with 18∶1 but not with 22∶6ω3 increased the quantity of TG secreted into the culture medium relative to controls. Treatment with 22∶6ω3 caused a greater accumulation of intracellular TG than 18∶1. This arises in part from the preferential retention of 22∶6ω3‐enriched TG by the hepatocytes. At 24 hr, there was no longer any difference in the net secretion of TG by 18∶1 and 22∶6ω3‐treated cells, which may be a consequence of the reuptake of TG‐esterified 18∶1. There was no reuptake of TG‐esterified 22∶6ω3. We conclude that inhibition of hepatocyte TG synthesis is not obligatory for 22∶6ω3‐induced diminution of TG secretion.
Synthesis of 6‐phosphatidyl‐L‐ascorbic acid by phospholipase D
Authors: Nagao Akihiko , Ishida Nobuaki , Terao Junji
Published: November 2006

Phospholipase D (EC 3.1.4.4) ofStreptomyces species was found to catalyze transphosphatidylation to L‐ascorbic acid from phosphatidylcholine (PC) in a biphasic reaction system. The product was identified as 1,2‐diacyl‐sn‐glycero‐3‐phospho‐6′‐L‐ascorbic acid (PA‐AsA) by mass spectrometry and nuclear magnetic resonance spectroscopy. The optimal pH of transphosphatidylation was 4.5 and the rate of PA‐AsA formation increased as concentrations of L‐ascorbic acid increased. The conversion of PC to PA‐AsA was greater than 80%. PA‐AsA was found to be more resistant to hydrolysis by phospholipase D than was PC.
Effect of chitosan feeding on intestinal bile acid metabolism in rats
Authors: Fukada Yasuhiko , Kimura Koji , Ayaki Yoshikazu
Published: November 2006

The effect of chitosan feeding (for 21 days) on intestinal bile acids was studied in male rats. Serum cholesterol levels in rats fed a commercial diet low in cholesterol were decreased by chitosan supplementation. Chitosan inhibited the transformation of cholesterol to coprostanol without causing a qualitative change in fecal excretion of these neutral sterols. Increased fiber consumption did not increase fecal excretion of bile acids, but caused a marked change in fecal bile acid composition. Litcholic acid increased sigificantly, deoxycholic acid increased to a leasser extent, whereas hyodeoxycholic acid and the 6β‐isomer and 5‐epimeric 3α‐hydroxy‐6‐keto‐cholanoic acid(s) decreased. The pH in the cecum and colon became elevated by chitosan feeding which affected the conversion of primary bile acids to secondary bile acids in the large intestine. In the cecum, chitosan feeding increased the concentration of α‐,β‐, and ω‐muricholic acids, and lithocholic acid. However, the levels of hyodeoxycholic acid and its 6β‐isomer, of monohydroxy‐monoketo‐cholanoic acids, and of 3α, 6ξ, 7ξ‐trihydroxy‐cholanoic acid decreased. The data suggest that chitosan feeding affects the metabolism of intestinal bile acids in rats.
Digestion and absorption of free and esterified fish oil fatty acids in rats
Authors: De Schrijver Remi , Vermeulen Daniel , Backx Suzanne
Published: November 2006

This study was designed to test the hypotheses that digestibility and post‐absorption metabolism of fish oil are influenced by impaired lipolysis and by the stereospecific composition of its triacylglycerols. Male Wistar rats were fed nonpurified diets containing one of the following fat sources: 9% native fish oil (NFO), 9% autorandomized fish oil (RFO), 8.1% fish oil‐derived free fatty acids (FO‐FFA) plus 0.9% glycerol, or 9% soybean oil (SO) as a reference fat. In a 24‐day balance study, apparent digestibility of total dietary fat averaged 93.1% in the SO, NFO and RFO groups, and 90.9% in the FO‐FFA group. Randomization of fish oil had no effect on apparent digestibility of individual fatty acids. In rats fed FO‐FFA, apparent absorption of saturated and monounsaturated fatty acids was lower when compared to the NFO and RFO groups. Feeding the FO‐FFA diet tended to increase plasma triglyceride content. The hypocholesterolemic effect of polyunsaturated n−3 fatty acids was not influenced by the dietary source. Similar effects on fatty acid profiles of plasma and liver phospholipids were caused by the NFO, RFO and the FO‐FFA diets. We conclude that once polyunsaturated n−3 fatty acids are absorbed, their effect on lipid metabolism is not determined by the dietary source.
Separation of cholesterol, and fatty acylglycerols, acids and amides by thin‐layer chromatography
Authors: Bilyk Alexander , Piazza George J. , Bistline Raymond G. , Haas Michael J.
Published: November 2006

A rapid unidimensional thin‐layer chromatographic (TLC) method for the separation of neutral lipids is described, using two sequential solvent systems of different polarity. Excellent separations of mono‐, di‐ and triglycerides, fatty acids, fatty amides, and cholesterol are thereby achieved. Separation is accomplished at room temperature and requires 25 min.
Effect of clofibric acid on the molecular species composition of diacyl glycerophosphocholine of rat liver microsomes
Authors: Nakagawa Yasuhito , Waku Keizo , Hirose Akihiko , Kawashima Yoichi , Kozuka Hiroshi
Published: November 2006

The effect of administeringp‐chlorophenoxyisobutyric (clofibric) acid to rats on the molecular species composition of diacyl‐glycerophosphocholine (GPC) of rat liver microsomes was studied. Microsomal choline glycerophospholipids were converted to 1,2‐diradyl‐3‐acetylglycerol and were separated into molecular species by reverse‐phase high performance liquid chromatography. Diacyl‐GPC consisted of 17 different molecular species. The predominant species were arachidonoyl derivatives, such as 18∶0–20∶4 (22.2% of the total) and 16∶0–20∶4 (22.0%). Administration of clofibric acid to rats caused a marked increase in 16∶0–18∶1 species of diacyl‐GPC from 8% to 30%, making these the predominant species of diacyl‐GPC in clofibric acid‐fed rats. Also, a significant decrease (50% of controls) in 18∶0–18∶2 and 18∶0–20∶4 species was observed, whereas the decrease in molecular species containing 16∶0 at the 1‐position such as 16∶0–18∶2 and 16∶0–20∶4 was small (approximately 85% of control). The results show that clofibric acid caused marked changes in the molecular species composition of diacyl‐GPC. The participation of 1‐acyl‐GPC acyltransferase and stearoyl‐CoA desaturase in the regulation of the molecular species composition of diacyl‐GPC is discussed.
Altered metabolism and cell surface expression of glycosphingolipids caused by vitamin E in cultured murine (K3T3) reticulum sarcoma cells
Authors: Yogeeswaran Ganesa , Mbawuike Innocent N.
Published: November 2006

Vitamin E caused a generalized reduction in the metabolism and cell surface expression of glycosphingolipids (GSL) in cultured Kirsten murine sarcoma virustransformed nonproducer (K3T3) cells. Metabolism of gangliosides was decreased two‐ to fourfold in cells treated for 72 hr with 1 and 2 μg/ml but not with 12 μg/ml vitamin E compared to control cultures. This was demonstrated by a quantitative reduction in precursor3H‐galactose label incorporated in ganglioside fraction and further substantiated by thin layer chromatography of colorimetrically and radiochemically detected GSL homologues. The composition of neutral GSL homologues was only slightly changed. The cell surface expressions of sialoglycoconjugates, analyzed by selective periodateborotritide labeling, were also diminished quantitatively. These results are discussed in light of a previously demonstrated increase in antigenicity of K3T3 cells treated with vitamin E and the reduced tumorigenicity of these cells when transplanted into mice fed vitamin E‐supplemented diets.
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

To 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

The 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

The 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

The 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

Effects 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

Australian 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.