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At least 1,279 records · Page 71Linked to original sources
PubMed1988

Biosynthesis of branched-chain fatty acids in Bacillus subtilis. A decarboxylase is essential for branched-chain fatty acid synthetase.

Branched long-chain fatty acids of the iso and anteiso series are synthesized in many bacteria from the branched-chain alpha-keto acids of valine, leucine, and isoleucine after their decarboxylation followed by chain elongation. Two distinct branched-chain alpha-keto acid (BCKA) and pyruvate decarboxylases, which are considered to be responsible for primer synthesis, were detected in, and purified in homogenous form from Bacillus subtilis 168 strain by procedures including ammonium sulfate fractionation and chromatography on ion exchange, reversed-phase, and gel absorption columns. The chemical and catalytic properties of the two decarboxylases were studied in detail. The removal of BCKA decarboxylase, using chromatographic fractionation, from the fatty acid synthetase significantly reduced its activity. The synthetase activity was completely lost upon immunoprecipitation of the decarboxylase. The removal of pyruvate decarboxylase by the above two methods, however, did not affect any activity of the fatty acid synthetase. Thus, BCKA decarboxylase, but not pyruvate decarboxylase, is essential for the synthesis of branched-chain fatty acids. The very high affinity of BCKA decarboxylase toward branched-chain alpha-keto acids is responsible for its function in fatty acid synthesis.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMedDate not supplied

Microsomal oxidation of dodecylthioacetic acid (a 3-thia fatty acid) in rat liver.

[1-14C]Dodecylthioacetic acid (DTA), a 3-thia fatty acid, is omega (omega-1)-hydroxylated and sulfur oxygenated at about equal rates in rat liver microsomes. In prolonged incubations DTA is converted to omega-hydroxydodecylsulfoxyacetic acid. omega-Hydroxylation of DTA is catalysed by cytochrome P450IVA1 (or a very closely related isoenzyme in the same gene family), the fatty acid omega-hydroxylating enzyme. It is absolutely dependent on NADPH and inhibited by CO, and lauric acid is a competing substrate. omega-Hydroxylation of DTA is increased by feeding tetradecylthioacetic acid (TTA), a 3-thia fatty acid, for 4 days to rats. omega-Hydroxylation of [1-14C]lauric acid is also induced by TTA and other 3-thia carboxylic acids. A close relationship was observed between induction of microsomal omega-hydroxylation of fatty acid and palmitoyl-CoA hydrolase activity. DTA is omega-hydroxylated at about the same rate as the physiological substrate lauric acid. The sulfur oxygenation of DTA is catalysed by liver microsomal flavin-containing monooxygenase (FMO) (EC 1.14.13.8). It is dependent on either NADH or NADPH. The Km value for NADH was approx. five times larger than the Km value for NADPH. It is inhibited by methimazole and not affected by CO. It is not induced by TTA.

Animals↗
PubMedDate not supplied

Differential influence of pre- and post-delta-6-desaturation n6 polyunsaturated fatty acids on fibroblasts in culture, compared to n9 monounsaturated and n3 polyunsaturated fatty acids.

There is now considerable evidence that polyunsaturated fatty acids (PUFA) are effective in vitro at limiting the growth of cancer cells while not affecting normal cells to the same extent. Twenty carbon PUFA, especially of the n3 series, have been shown to be particularly potent; while the eighteen carbon n6 fatty acid, linoleic acid has been implicated in growth stimulation of breast cancer. We report here on the comparative effects of a range of eighteen and twenty carbon fatty acids of varying degrees of unsaturation on normal and transformed fibroblasts in culture. All moieties of the n3 series showed high potency in limiting transformed cell growth, while cis and trans monounsaturates and pre-delta-6-desaturation n6 polyunsaturates induced a mixed response, even inducing comparative growth stimulation with some fatty acid concentrations.

Cell Line, Transformed↗
PubMed1999

Inhibition of plasminogen activator inhibitor-1 by 11-keto-9(E),12(E)-octadecadienoic acid, a novel fatty acid produced by Trichoderma sp.

We have recently found a novel fatty acid, 11-keto-9(E),12(E)-octadecadienoic acid (KOD), that enhances fibrinolytic activity of endothelial cells. The mechanism of action of KOD has been investigated. KOD increased 2-fold the plasmin activity of bovine aortic endothelial cells at 250 microM. The stimulation was dependent on plasminogen and was inhibited by anti-urokinase, whereas KOD did not enhance the urokinase-catalyzed plasminogen activation and the resulting plasmin activity in a cell-free system. Neither the production of urokinase nor the conversion of pro-urokinase to the active, two-chain form was elevated by KOD, but it decreased plasminogen activator inhibitor-1 (PAI-1) activity of cells and inactivated PAI-1 irreversibly in a purified system. These results demonstrated that the KOD enhancement of endothelial fibrinolytic activity was mediated, at least in part, by inactivation of PAI-1.

Animals↗
PubMed2006

Validity of protein, retinol, folic acid and n-3 fatty acid intakes estimated from the food-frequency questionnaire used in the Danish National Birth Cohort.

OBJECTIVE: To validate intakes of protein, folic acid, retinol and n-3 fatty acids estimated from a food-frequency questionnaire in week 25 of pregnancy (FFQ-25). DESIGN: Validation was done against a 7-day weighed food diary (FD) and biomarkers of the nutrients in gestation week 32-38. SUBJECTS AND SETTING: The FFQ-25 to be validated was used in the Danish National Birth Cohort comprising 101 042 pregnant Danish women, of whom 88 participated in the present validation study. RESULTS: Estimated intakes of protein, retinol and folic acid did not differ significantly between the two dietary methods, but intake of n-3 fatty acids was one third larger when estimated from the FFQ-25. The intakes estimated from the two dietary methods were all significantly correlated, ranging from 0.20 for retinol intake to 0.57 for folic acid intake. Sensitivities of being correctly classified into low and high quintiles were between 0.22 and 0.77, and specificities were between 0.62 and 0.89. Urinary protein content did not correlate significantly with protein estimated from the FFQ (r = 0.17, P > 0.05), but did with intake estimated from the FD (r = 0.56, P < 0.0001). Erythrocyte folate correlated significantly with the estimated total intake from the FFQ (r = 0.55, P < 0.0001) and the FD (r = 0.52, P < 0.0001). No correlations with plasma retinol were found. Erythrocyte eicosapentaenoic acid (C20:5n-3) correlated significantly with n-3 fatty acids intake estimated from both the FFQ-25 (r = 0.37, P < 0.001) and the FD (r = 0.62, P < 0.0001). CONCLUSION: The FFQ-25 gives reasonable valid estimates of protein, retinol and folic acid intakes, but seems to overestimate intake of n-3 fatty acids.

Adult↗
PubMed1998

Comparison of the fatty acid compositions in intraepithelial and infiltrating lesions of the cervix: part I, total fatty acid profiles.

In the first part of this study, the possible role of essential total fatty acids and their metabolites during cervical carcinogenesis was investigated. Since membrane lipids play a key role in cell proliferation and differentiation, disturbances in the fatty acid compositions of cell membranes and the modulation of membrane fatty acid compositions received attention in several in vitro studies. There are, however, no reported studies where the actual total and free (unesterified) fatty acid compositions have been determined during the different stages of cervical carcinogenesis. In part I of this ex vivo study, the total fatty acid compositions of normal tissue, intraepithelial and infiltrating lesions of the cervix were compared. The fatty acid profiles that were determined make it possible to speculate about the metabolic pathways followed during cervical carcinogenesis. Lipids were extracted from biopsies of normal tissue (n=36), cervical intraepithelial lesions (n=47) and infiltrating lesions (n=47). Samples, from which the total fatty acid compositions were determined, were saponified, methylated and analysed by gas liquid chromatography (GLC). Essential fatty acid deficiency (EFAD) in the intraepithelial lesions, compared with normal tissue (linoleic acid, P< 0.01), and infiltrating lesions, compared with intraepithelial lesions (linoleic acid and arachidonic acid, P< 0.01) were observed. High levels of oleic acid were also observed when infiltrating lesions were compared with normal tissue (P< 0.01). This EFAD in cancer cells may result in many defective cell mechanisms. Although there are many risk factors for cervical cancer, the human papilloma virus has emerged over the past decade as the leading candidate to be an aetiological factor. There is ample evidence that human viral infections are associated with reduced levels of linoleic acid and thus participate in the depletion of essential fatty acids in cancer cells.

Arachidonic Acid↗
PubMed1993

Comparison of the effects of diets rich in stearic acid versus myristic acid and lauric acid on platelet fatty acids and excretion of thromboxane A2 and PGI2 metabolites in healthy young men.

The present study compared the effects of diets rich in stearic acid (C18:0) versus one high in lauric and myristic acid (C12:0, C14:0) on platelet phospholipid fatty acid levels and concentrations of urinary thromboxane B2 (TXB2) and 6-keto-PGF1 alpha, which are stable metabolites of thromboxane A2 (TXA2) and PGI2 and indicators of cardiovascular hemostasis. A diet high in dairy butter (B) was the source of C12:0 and C14:0; C18:0 was provided by diets high in cocoa butter (CB), milk chocolate (CHOC) or CB+B in a 4:1 ratio (MIX). A randomized, crossover double-blind experimental design was used. Experimental subjects (n = 15) consumed each diet for 26 days, with a 1-month washout period between each experimental period. Urine and blood were collected from each subject at the beginning and end of each dietary period. Urinary TXB2 and 6-keto-PGF1 alpha were analyzed by radioimmunoassay (RIA). There were no effects of diet on the 24-hour excretion of either metabolite or on the ratio of 6-keto-PGF1 alpha/TXB2, even though there were significant changes in the eicosanoid precursor, arachidonic acid (C20:4n-6), in platelet phospholipids. C20:4n-6 levels increased (44.8% +/- 1.0% to 47.1% +/- 1.3%; P < .05) in the phosphatidylethanolamine phospholipid subclass in subjects on the B diet and decreased in the phosphatidylcholine subclass on the CB diet (16.5% +/- 1.0% to 14.2% +/- 1.1%; P < .05) compared with baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1979

Temperature-induced changes in fatty acid unsaturation of Tetrahymena membranes do not require induced fatty acid desaturase synthesis.

The usual rise in phospholipid-bound palmitoleic acid of Tetrahymena pyriformis cells slowly acclimating to low temperature exposure can be prevented by cycloheximide. This reduction in fatty acid desaturation is not caused by specific inhibition of a temperature-induced synthesis of a fatty acid desaturase but rather by a general effect equally conspicuous in isothermal cells. Cycloheximide-inhibited cells chilled and analyzed quickly, before long term ill effects of the drug are expressed, exhibit the rise in unsaturated fatty acids typical of temperature-acclimating cells.

Animals↗
PubMed1980

[Dynamic study of the changes in the composition of fatty acids in serum lipid fractions under a diet rich in polyunsaturated fatty acids].

Appropriate adjustment of diet and specially reduction of the saturated fatty acids content is the cornerstone of correcting many hyperlipidemias. What we have tried in our study was first to show the evolution of the changes in the serum's fatty acids composition under a rich polyunsaturated fatty acids diet, second to find an index proving that the diet had correctly been taken. Chromatographic analysis were performed after ultracentrifugal separation of the lipoprotein fractions. Seven volunteers, non fat, and normolipemics were selected. Samples were collected every three or five days before and during the diet. The whole test lasted twenty days. What had been shown is that the linoleic acid content increased but the one of the oleic acid decreased in all lipoprotein fractions. Those changes are bestly illustrated by using the (formula: see text) ratio as a kinetic index. The triglycerid fraction modifications are faster than the phospholipid's one. Concerning the other fatty acids, the modifications are less spectacular : the palmitic acid decrease in every lipids fractions and the palmitoleic acid has a significant decrease only in the esterified cholesterol. And the stearic acid has no variation at least significatively.

Adult↗
PubMed1996

Effects of chain length and sulphur position of thia fatty acids on their incorporation into phospholipids in 7800 C1 hepatoma cells and isolated rat hepatocytes, and their effects on fatty acid composition of phospholipids.

Incorporation of thia fatty acids and their effects on the fatty acid composition in phospholipids has been investigated in 7800 C1 hepatoma cells and cultured hepatocytes. 3-Thia fatty acids of chain lengths from dodecyl-to hexadecyl-thioacetic acid were incorporated into phospholipids during a 3-day incubation. Longer and shorter 3-thia fatty acids were barely detectable. Tetradecylthioacetic acid, 3-thia stearate, and their delta9- desaturated derivatives were maximally incorporated into whole-cell phospholipids. The amount of tetradecylthioacetic acid incorporated into phospholipids of hepatoma cells remained almost identical in cells cultured for 3 days or adapted over a period of 1 year. Delta9-desaturated metabolites of long chain thia fatty acids (C13-to C16-S-acetic acid) were identified by GC-MS in phospholipids. 3-Thia stearate appeared to be the best substrated for delta9 desaturase. Incubation of hepatoma cells with thia fatty acids led to alterations in the amount of normal fatty acids in total phospholipids. The amounts of 16:0 and 18:1 decreased and 18:2 (n-6) and 20:5 (n-3) increased. Changes in the normal fatty acid composition of phospholipids were seen both with thia acids incorporated into phospholipids and those not incorporated. These effects, therefore, may be only partially dependent on displacement of normal fatty acids by thia fatty acids. Morris 7800 C1 hepatoma cell acyl-CoA synthetase (ACS) and peroxisomal acyl-CpA oxidase (ACO) were induced by thia fatty acids of all chain lengths, and with the sulphur atom(s) in different positions. Control experiments with hepatocytes revealed a similar incorporation of thia fatty acids in these physiologically more normal cells.

Acyl-CoA Oxidase↗
PubMed2001

Differential involvement of peroxisome-proliferator-activated receptors alpha and delta in fibrate and fatty-acid-mediated inductions of the gene encoding liver fatty-acid-binding protein in the liver and the small intestine.

Liver fatty-acid-binding protein (L-FABP) is a cytoplasmic polypeptide that binds with strong affinity especially to long-chain fatty acids (LCFAs). It is highly expressed in both the liver and small intestine, where it is thought to have an essential role in the control of the cellular fatty acid (FA) flux. Because expression of the gene encoding L-FABP is increased by both fibrate hypolipidaemic drugs and LCFAs, it seems to be under the control of transcription factors, termed peroxisome-proliferator-activated receptors (PPARs), activated by fibrate or FAs. However, the precise molecular mechanism by which these regulations take place remain to be fully substantiated. Using transfection assays, we found that the different PPAR subtypes (alpha, gamma and delta) are able to mediate the up-regulation by FAs of the gene encoding L-FABP in vitro. Through analysis of LCFA- and fibrate-mediated effects on L-FABP mRNA levels in wild-type and PPARalpha-null mice, we have found that PPARalpha in the intestine does not constitute a dominant regulator of L-FABP gene expression, in contrast with what is known in the liver. Only the PPARdelta/alpha agonist GW2433 is able to up-regulate the gene encoding L-FABP in the intestine of PPARalpha-null mice. These findings demonstrate that PPARdelta can act as a fibrate/FA-activated receptor in tissues in which it is highly expressed and that L-FABP is a PPARdelta target gene in the small intestine. We propose that PPARdelta contributes to metabolic adaptation of the small intestine to changes in the lipid content of the diet.

Animals↗
PubMed1982

Fatty acid accretion during perinatal brain growth in the pig. A model for fatty acid accretion in human brain.

1. Brain fatty acid composition in the fetal, full term and postnatal piglet was analyzed. 2. Changes in fatty acid content of developing pig brain parallel those found in the human. 3. Total fatty acids per gram of brain increase with post conceptional age. 4. Brain concentration of long chain derivatives of essential fatty acids, c18:2omega6 and c18:3omega3 increase during gestation while levels of shorter chain precursors (c18:2omega6 and c18:3omega3) remain low. 5. The results indicate that the developing piglet is an appropriate model, analogous to the human, for studies of changes in brain fatty acid content during neural development throughout the perinatal period.

Aging↗
PubMedDate not supplied

Collision-mediated transfer of long-chain fatty acids by neural tissue fatty acid-binding proteins (FABP): studies with fluorescent analogs.

Mammalian fatty acid-binding proteins (FABP) are a family of intracellular proteins (approx 15 kDa) that bind long-chain fatty acids (FA) with high affinity. They are believed to serve as cytoplasmic transporters of FA and to target FA to specific cellular sites of utilization. Several different FABPs are expressed in neural tissue, including brain FABP (B-FABP), myelin FABP (M-FABP), and heart FABP (H-FABP). We have previously shown that H-FABP transfers FAvia direct collisional interactions with acceptor model membranes. In the present studies, we use a fluorescence resonance energy transfer (FRET) assay to examine the rate and mechanism of transfer of a fluorescent long-chain fatty acid from B-FABP to phospholipid vesicles. The rate of transfer is shown to be independent of buffer ionic strength and dramatically enhanced by the presence of specific anionic phospholipids. These results are consistent with a mechanism by which FA are transferred from B-FABP to phospholipid membranes by a transient collision-based mechanism.

Animals↗
PubMed1992

Effect of dietary polyunsaturated fatty acid concentration on performance, fat deposition, and carcass fatty acid composition in broiler chickens.

The effect of dietary polyunsaturated fatty acid (PUFA) concentration on body fat deposition and composition in broiler chickens was studied. Twenty-day-old birds were fed five isocaloric diets supplemented with different combinations of tallow and vegetable oils. Contents of abdominal adipose tissue (AAT) as well as body fat were determined at 40 days of age. A significant linear effect was observed between dietary PUFA and feed utilization. Fatty acid (FA) profiles in AAT and total body fat were correlated to dietary PUFA content, with the main effect of higher dietary PUFA being a reduction in monoenoic FA (C16:1 and C18:1) and an increase in C18:2. The effect of dietary PUFA on the saturated FA (C16:0 and C18:0) was small and not statistically significant. Increased dietary PUFA modified FA composition such that C18:2, rather than C18:1 became the dominant FA in AAT. In that respect, greater changes were observed in FA composition of AAT, as compared with that on the whole carcass. The deposition of saturated and monoenoic FA in the whole carcass during the experimental period was related to dietary PUFA content in a quadratic manner. However, deposition of C18:2 and C18:3 was not affected by intake and their utilization (deposition:intake ratio) was reduced in a manner parallel to their dietary levels.

Adipose Tissue↗
PubMed1988

Myocardial metabolism of radioiodinated methyl-branched fatty acids.

Methylated fatty acids labeled with radioactive iodine have been proposed as a means of studying regional myocardial uptake of fatty acids in man. To investigate the methylated fatty acid that is best adapted for an assessment of uptake, we have studied the influence of the number and the position of the methyl groups of IFA intracellular metabolism; 16-iodo-2-methyl-hexadecanoic (mono-alpha), 16-iodo-2,2-methyl hexadecanoic (di-alpha), 16-iodo-3-methyl-hexadecanoic (mono-beta), and 16-iodo-3,3-methyl-hexadecanoic (di-beta) acids were injected into the coronary arteries of isolated rat hearts. Intracellular analysis shows that the degradation of mono-alpha was always lower than that of IHA and the storage was always much higher. The differences between mono-beta and IHA were similar to those observed with mono-alpha, but were much more pronounced. With the two dimethylated IFAs there was an inhibition of both oxidation and esterification which led to an accumulation of free FAs in myocardial cells. In conclusion, mono-beta, di-alpha, and di-beta are potentially suitable for studying the cellular uptake of IFA since all of them, and particularly the dimethylated IFAs, have a low oxidation rate.

Animals↗
PubMed2004

Mono-unsaturated fatty acids protect against beta-cell apoptosis induced by saturated fatty acids, serum withdrawal or cytokine exposure.

Long-chain saturated fatty acids are cytotoxic to pancreatic beta-cells while shorter-chain saturated and long-chain unsaturated molecules are better tolerated. Mono-unsaturated fatty acids are not, however, inert since they inhibit the pro-apoptotic effects of saturated molecules. In the present work we show that the mono-unsaturates palmitoleate (C16:1) or oleate (C18:1) also cause marked inhibition of apoptosis induced by exposure of clonal BRIN-BD11 beta-cells to serum withdrawal or a combination of interleukin-1beta plus interferon-gamma. This response was dose-dependent and not accompanied by changes in NO formation. Taken together, the results suggest that mono-unsaturated fatty acids regulate a distal step common to several apoptotic pathways in pancreatic beta-cells.

Animals↗