bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractDiets 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

AbstractWeanling 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

AbstractA 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

AbstractWhen 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

AbstractThe 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

AbstractSusceptibility 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

AbstractThe 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

AbstractThe 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

AbstractMice 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

AbstractRat 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

AbstractWe 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

AbstractPhospholipase 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractThe 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

AbstractVitamin 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.