Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FATTY ACIDS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,531 records · Page 85Linked to original sources
PubMed1997

Ethyl palmitate and ethyl oleate are the predominant fatty acid ethyl esters in the blood after ethanol ingestion and their synthesis is differentially influenced by the extracellular concentrations of their corresponding fatty acids.

The possibility that fatty acid ethyl esters (FAEEs), esterification products of fatty acids and ethanol, are mediators of ethanol-induced organ damage was suggested by an autopsy study in which individuals who died while acutely intoxicated were found to have FAEEs predominantly in the organs damaged by ethanol abuse. We initially observed in human subjects after ethanol consumption that there is a marked preference for the synthesis of ethyl palmitate and ethyl oleate over other FAEEs. To investigate the basis for this relative fatty acid specificity for FAEE synthesis, we used an in vitro system of Hep G2 cells incubated with ethanol. The cells were capable of synthesizing FAEEs upon exposure to ethanol and they showed a preference for synthesis of ethyl palmitate and ethyl oleate, as was found in human plasma after ethanol ingestion. This finding allowed us to explore the metabolic preference for palmitate and oleate for FAEE synthesis at the biochemical level using intact cells. We demonstrated that the preferential selection of palmitate and oleate for FAEE synthesis was not likely to be the result of specificity for palmitate and oleate by FAEE synthase or preferential uptake of palmitate and oleate by Hep G2 cells. In studies to determine whether the preference for ethyl palmitate and ethyl oleate synthesis was a result of higher concentrations of palmitate and oleate in the extracellular medium, we observed that the synthesis of ethyl oleate, ethyl linoleate, and ethyl arachidonate, but not ethyl palmitate, is influenced by the extracellular concentration of its corresponding fatty acid. The results of our studies indicate that ethyl palmitate and ethyl oleate are the predominant ethyl esters synthesized, that there is no preferential uptake or enzyme affinity for their fatty acid precursors to explain the predominance, and that ethyl palmitate synthesis is uniquely unaffected by the concentration of palmitate in the extracellular medium.

Acyltransferases↗
PubMed1995

Tetradecylthioacetic acid (a 3-thia fatty acid) decreases triacylglycerol secretion in CaCo-2 cells.

The effects of the hypolipidemic fatty acid analogue tetradecylthioacetic acid (TTA) on synthesis and secretion of lipoproteins in CaCo-2 cells were studied. Radiolabeled tetradecylthioacetic acid was absorbed and metabolized as efficiently as oleic acid, although a discrepancy in the metabolic fate was evident. Whereas tetradecylthioacetic acid was incorporated into cell-associated triacylglycerol to the same extent as normal fatty acids (e.g., oleic acid and palmitic acid), the amount of triacylglycerol secreted from cells incubated with tetradecylthioacetic acid was 8 to 10 times lower than the amount secreted from cells incubated with palmitic acid and oleic acid, respectively. On the other hand, there was an enhanced incorporation of tetradecylthioacetic acid into cell-associated and secreted phospholipids. Despite incorporation of tetradecylthioacetic acid into cellular triacylglycerol, unlike oleic acid, tetradecylthioacetic acid did not stimulate production of triacylglycerol-rich particles. Ultracentrifugation of basolateral media from cells incubated with tetradecylthioacetic acid revealed low amounts of triacylglycerol in the triacylglycerol-rich fraction (p < 1.006 g/ml), suggesting secretion of lipoproteins with a higher density than chylomicrons. However, the present study shows that the stimulated triacylglycerol secretion caused by oleic acid was inhibited in the presence of TTA. The decreased rate of triacylglycerol secretion from these cells was not accompanied by a stimulation of fatty acid oxidation. Based on these findings, we therefore suggest that tetradecylthioacetic acid mainly affects secretion of lipoproteins in CaCo-2 cells.

Cell Line↗
PubMed1972

Effect of unsaturated fatty acids on the development of respiration and on protein synthesis in an unsaturated fatty acid mutant of Saccharomyces cerevisiae.

The extent of development of respiratory function induced by aeration of an anaerobically grown unsaturated fatty acid auxotroph of Saccharomyces cerevisiae is determined by the availability, endogenous or externally supplied, of unsaturated fatty acid. The synthesis of mitochondrial and cytoplasmic enzymes during aeration appears to have a similar basis of regulation by available unsaturated fatty acid. Levels of unsaturated fatty acid that permit the synthesis of mitochondrial enzymes also result in a substantial stimulation of cellular protein synthesis.

Anaerobiosis↗
PubMed2005

Yeast adaptation to 2,4-dichlorophenoxyacetic acid involves increased membrane fatty acid saturation degree and decreased OLE1 transcription.

Yeast cells adapted to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) exhibit a plasma membrane less susceptible to 2,4-D-induced disruption and are more tolerant than unadapted cells to lethal concentrations of the herbicide. These cells, adapted to grow in the presence of increasing concentrations of 2,4-D, were found to exhibit a dose-dependent increase of the saturation degree of membrane fatty acids, associated to the higher percentage of stearic (C(18:0)) and palmitic (C(16:0)) acids, and to the decreased percentage of palmitoleic (Delta9-cisC(16:1)) and oleic (Delta9-cisC(18:1)) acids. The decreased transcription of the OLE1 gene (encoding the Delta9 fatty acid desaturase that catalyses the conversion of palmitic and stearic acids to palmitoleic and oleic acids, respectively) registered in 2,4-D adapted cells suggests that yeast adaptation to the herbicide involves the enhancement of the ratio of saturated (C(16:0) and C(18:0)) to monounsaturated (C(16:1) and C(18:1)) membrane fatty acids through a reduced OLE1 expression.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Determination of docosahexaenoic acid and n-3 fatty acids in refined fish oils by 1H-NMR spectroscopy: IUPAC interlaboratory study.

A high-resolution proton nuclear magnetic resonance (NMR) method for determining the concentration (mg/g) of docosahexaenoic acid (DHA), the molar proportion (mol%) of DHA, and the molar proportion of total n-3 fatty acids in fish oils was validated by an IUPAC interlaboratory study (the Commission VI-6 on Oils, Fats, and Derivatives WG 3/98). Thirteen laboratories from 5 countries tested 6 pairs of blind duplicate fish oils: a refined tuna oil, 2 extracted tuna oils, an extracted bonito oil, an extracted salmon oil, and an extracted sardine oil ranging from 9 to 30 mol% DHA and from 20 to 35 mol% n-3 fatty acids. Before 1 D-proton NMR measurements with 300-500 MHz instruments, oil samples were weighed and diluted with deuterochloroform solution containing ethylene glycol dimethyl ether as internal standard. To achieve precise performance, a detailed procedure for signal area measurement was described in the protocol, and all participants were instructed about the critical importance of following the protocol. Statistical performances with invalid and outlier data removed were as follows: repeatability relative standard deviations (RSDr) ranged from 0.91 to 2.62% and reproducibility relative standard deviation (RSDR) ranged from 1.73 to 4.27% for DHA concentration (mg/g); RSDr ranged from 0.39 to 2.06%, and RSDR ranged from 0.59 to 3.46% for mol% DHA; RSDr ranged from 0.23 to 0.90% and RSDR ranged from 0.85 to 2.01 % for mol% total n-3 fatty acids. The method is expected to be recommended by IUPAC.

Docosahexaenoic Acids↗
PubMed1985

Onset of changes in phospholipid fatty acid composition and prostaglandin synthesis following dietary manipulation with n-6 and n-3 fatty acids in the rat.

A synthetic diet preparation supplemented with 10% by weight of either safflower oil, hydrogenated coconut oil containing 3% safflower oil, or 'max EPA' fish oil was fed to rats over a 8-week period. Serial measurements of serum fatty acids, serum thromboxane B2 and urinary prostaglandin excretion were taken during the treatment period to assess the rate of change in fatty acid composition and prostaglandin synthesis following dietary manipulation. There was no significant change in weight gain between the dietary groups during the treatment period. Significant changes in serum fatty acids occurred within 48 h of treatment, with the 'max EPA' oil group having arachidonic acid levels reduced by 23% (P less than 0.01) compared to the coconut oil group. Conversely, rats fed safflower oil had an 18% enhancement of arachidonic acid during the same time period. Whole blood synthesis of thromboxane B2 was significantly depressed (P less than 0.01) after 48 h in rats fed 'max EPA' oil compared to the safflower oil or coconut oil groups. This suppression reached a maximum of 65% (P less than 0.001) after 7 days of dietary 'max EPA' oil treatment. The safflower oil and coconut oil-fed groups showed the same levels of serum thromboxane B2 production over the treatment period. Urinary excretion of both 6-ketoprostaglandin F1 alpha and prostaglandin E2 varied significantly (P less than 0.01) between the groups after 7 days of dietary treatment. Rats fed 'max EPA' oil had depressed urinary prostanoid excretion compared to the safflower and coconut oil groups which remained very similar to each other. After the 8-week treatment period rats were killed and the phospholipid fatty acid composition and prostaglandin-generating capacity of platelets, aorta and renal tissue was examined. Prostanoid production by kidney cortex and medulla and segments of aorta was consistently suppressed in rats fed 'max EPA' oil. These observations correlated well with changes in the phospholipid fatty acid profiles in these tissues. This study shows rapid changes in serum fatty acids and thromboxane B2 generation following dietary manipulation, while changes in urinary excretion or prostanoid metabolites occur only after a longer time period.

Animals↗
PubMed1996

The effect of intracellular pH on long-chain fatty acid uptake in 3T3-L1 adipocytes: evidence that uptake involves the passive diffusion of protonated long-chain fatty acids across the plasma membrane.

To understand the mechanism of long-chain fatty acid permeation of the plasma membrane in mammalian cells, the effects of changes in the cytoplasmic pH on the internalization of physiologically relevant, submicromolar concentrations of uncomplexed long-chain fatty acids were investigated in 3T3-L1 adipocytes. The acidification of the cytoplasm upon NH4Cl prepulsing of intact cells was accompanied by a rapid reduction of cellular long-chain fatty acid uptake (measured as the total accumulation of [9,10-3H]oleate). This was followed by a slow recovery to normal levels of uptake as the cytoplasmic pH recovered. Conventional filtration assays do not distinguish between fatty acid movement across the plasma membrane and intracellular steps, such as binding to cytoplasmic fatty acid-binding proteins or metabolism. While the in vitro binding of a photoreactive fatty acid, 11-m-diazirinophenoxy[11-3H]undecanoate, to a cytoplasmic fatty acid-binding protein was insensitive to changes in pH from pH 7.5 to 5.5, the in vitro conversion of oleate into oleoyl-CoA by cellular acyl-CoA synthetase decreased dramatically. Therefore, the labelling of the 15 kDa cytoplasmic fatty acid-binding protein in intact cells by the photoreactive fatty acid was used as a more direct measure of the permeation of the probe across the plasma membrane. Acidification of the cytoplasm resulted in an immediate reduction in the labelling of this protein in intact adipocytes. Its photolabelling recovered, however, upon the recovery of the cytoplasmic pH to normal levels. This was due to effects of the cytoplasmic pH on the permeation of the photoreactive fatty acid across the plasma membrane rather than its binding to the 15 kDa protein or metabolism in vivo. This is the first demonstration that the movement of physiologically relevant, submicromolar concentrations of uncomplexed long-chain fatty acids across the plasma membrane of intact cells is coupled to the cytoplasmic pH and suggests that it occurs by the diffusion of the protonated long-chain fatty acid through the lipid bilayer.

3T3 Cells↗
PubMed1990

Fatty acid metabolism in human lymphocytes. I. Time-course changes in fatty acid composition and membrane fluidity during blastic transformation of peripheral blood lymphocytes.

The time-course changes in fatty acid composition of human T-lymphocytes during blastic transformation were analysed, as well as the variations in membrane fluidity determined by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), using a fluorescence-activated cell sorter. The more important changes observed, in activated relative to quiescent cells, started after 24 h and consisted in an increase in the proportion of oleic (18:1(n - 9)), docosapentaenoic (22:5(n - 3)) and docosahexaenoic (22:6(n - 3)) acids and a decrease in that of linoleic (18:2(n - 6)) and arachidonic (20:4(n - 6)) acids. This represented a relative increase of 26% for 18:1, 56% for 22:5 and 84% for 22:6 in peripheral blood mononuclear cells (PBMC) and 35%, 182% and 94%, respectively, in purified T-lymphocytes, both activated for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and 19%, respectively, for 72 h. The decrease in n - 6 fatty acids was of 42% for 18:2 and 14% for 20:4 in PBMC and 30% and phosphatidylethanolamine) rather than neutral lipids. The 18:1/18:0 ratio increased greatly in major cell phospholipids. The proportion of 20:4, 22:5 and 22:6 in phosphatidylinositol was not significantly altered after 72 h of activation. The molar ratio cholesterol/phospholipids was reduced in 72-h-activated lymphocytes (0.29) compared to quiescent cells (0.5). On the other hand, the stimulation of human T-lymphocytes caused a significant decrease in the order parameter (S) of DPH, according to the observed changes in lipid composition. After 72 h in culture, the S value for quiescent and stimulated T-lymphocytes was 0.530 and 0.326, respectively. In conclusion, the blastic transformation of human T-lymphocytes is associated with changes in lipid composition which modify the physical properties of their membranes. These modifications could modulate, in turn, the activity of membrane proteins implicated in the process of blastic transformation.

Cells, Cultured↗
PubMed1979

Fatty-acid synthesis in lactating-goat mammary gland. 1. Medium-chain fatty-acid synthesis.

Tissue slices from lactating goat-mammary gland synthesized short (C4:0 and C6:0), medium (C8:0 and C10:0) and long-chain (C12:0 to C16:0) fatty acids in proportions similar to that found in goat milk fat. In contrast, the particle-free supernatant fraction and the purified fatty acid synthetase from this tissue synthesized predominantly short-chain and long-chain fatty acids. Terminating acyl-thioesterases of low molecular weight could not be detected in the particle-free supernatant. Addition of the microsomal fraction to the particle-free supernatant induced the synthesis of medium-chain fatty acids in proportions which were similar to those found in goat milk fat.

Acetyl Coenzyme A↗
PubMed1961

FATTY ACID METABOLISM IN SERRATIA MARCESCENS I. : Oxidation of Saturated Fatty Acids by Whole Cells.

Bishop, D. G. (University of Sydney, Sydney, Australia), and J. L. Still. Fatty acid metabolism in Serratia marcescens. J. Bacteriol. 82:370-375. 1961.-A study has been made of the oxidation of saturated fatty acids containing between two and 18 carbon atoms by whole cells of the bacterium, Serratia marcescens. This organism was found to be capable of oxidizing all of the acids tested, but variations in the rate and total oxygen uptake were found. These variations were dependent on the length of the carbon chain in the substrate molecule and the pH of the reaction mixture. The concept that these variations are due to a cellular permeability barrier to the substrate is discussed.

Journal Article↗
PubMed1990

Reversal of the arrhythmogenic effects of long-term saturated fatty acid intake by dietary n-3 and n-6 polyunsaturated fatty acids.

This study investigated whether the adverse influences of dietary saturated animal fatty acids (SF) on vulnerability to cardiac arrhythmias in rats could be modified by crossover in maturity to diets rich in polyunsaturated fatty acids (PUFAs). The arrhythmia model was coronary artery occlusion and reperfusion under anesthesia. Animals were fed commercial stock diet (4% fat wt:wt) supplemented (12% wt:wt) with fat (final diets, 35% energy as fat). Of rats fed the SF diet for 9 and 18 mo, ventricular fibrillation (VF) occurred in 71% during occlusion and in 86% on reperfusion. Mortality from VF was 0% after 9 mo on the SF diet but 67% after 18 mo. Dietary crossover to n-3 (tuna-fish oil) or n-6 (sunflower-seed oil) PUFA-supplemented diets at 9 mo reduced arrhythmias (VF incidence less than 30% in occlusion and reperfusion) and mortality (0%). The n-3 PUFAs were most effective. Dietary interventions can be effective even when introduced in mature, high-risk animals and may be of benefit in reducing risk of sudden cardiac death.

Age Factors↗
PubMed1997

Fatty acid unsaturation in the red alga Porphyridium cruentum. Is the methylene interrupted nature of polyunsaturated fatty acids an intrinsic property of the desaturases?

Polyunsaturated fatty acids (PUFAs) exogenously supplied to the red microalga Porphyridium cruentum were incorporated into cellular lipids. All the C18 PUFAs studied were desaturated by a delta 6-desaturase and all the C20 PUFAs by a delta 5-desaturase. The latter enzyme desaturated even 20:2(11, 14) to 20:3(5, 11, 14) and 20:3(11, 14, 17) to 20:4(5, 11, 14, 17). We infer the existence of several fatty acid desaturases, with different chain length specificities. Furthermore, the introduction of double bonds in a methylene interrupted pattern, at least for alpha-type desaturase such as the delta 5- and delta 6-desaturases, is not an intrinsic property of the enzyme but a consequence of the arrangement of the pre-existing double bonds in the fatty acid substrate.

Eukaryota↗