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Results for “PALMITIC ACID”

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PubMed1993

Changes in membrane fluidity modulate heat shock gene expression and produced attenuated strains in the dimorphic fungus Histoplasma capsulatum.

In the dimorphic fungus Histoplasma capsulatum the expression of heat shock genes is modulated by addition of fatty acids. Addition at 25 degrees C of saturated fatty acid (palmitic acid) to mycelia of H. capsulatum induced a significant increase in heat shock mRNAs transcription when cells were heat shocked. Conversely, treatments with unsaturated fatty acid (oleic acid) drastically reduced the level of heat shock gene transcription at 37 degrees C, and no detectable levels were measurable with 2 mM. Addition of saturated fatty acid induced a thermotolerant state and mitochondria retained ATPase activity coupled to electron transport under severe heat shock conditions and shortened the time required for mycelium-to-yeast phase transition. Conversely, addition of unsaturated fatty acids uncoupled mitochondrial electron transport and prolonged considerably the time required for phase transition at the same temperatures. A virulent strain, if treated with unsaturated fatty acid under condition in which no heat shock was detectable, lost its virulence probably as a consequence of decreased ability to adapt to the new living condition present in the host.

Cell Membrane↗

PubMed2001

Studies on effects of dietary fatty acids as related to their position on triglycerides.

This article reviews published literature on how the stereospecific structure of dietary triglycerides may affect lipid metabolism in humans. Animal studies have shown enhanced absorption of fatty acids in the sn-2 position of dietary triglycerides. Increasing the level of the saturated fatty acid palmitic acid in the sn-2 position (e.g., by interesterification of the fat to randomize the positions of the fatty acids along the glycerol backbone) has been shown in rabbits to increase the atherogenic potential of the fat without impacting levels of blood lipids and lipoproteins. In contrast, enhancing the level of stearic acid in the sn-2 position has not been found to affect either atherogenic potential or levels of blood lipids and lipoproteins in rabbits. Fatty acids other than palmitic and stearic have not been studied systematically with respect to possible positional effects. A limited number of human studies have shown no significant effects of interesterified fats on blood lipid parameters. However, it is unknown whether modifying the stereospecific structure of dietary triglycerides would affect atherogenicity or other long-term health conditions in humans. It is possible that incorporation of palmitic acid into the sn-2 position of milk fat is beneficial to the human infant (as a source of energy for growth and development) but not to human adults. Additional research is needed to determine whether processes like interesterification, which can be used to alter physical parameters of dietary fats (e.g., melting characteristics), may result in favorable or unfavorable long-term effects in humans.

Absorption↗

PubMed1981

Phospholipids in the developing rat liver: fatty acid content and composition.

Fatty acid content and composition of hepatic phospholipids was studied in rats during the fetal and postnatal period of development. Total phospholipid fatty acid content showed increases related to age including an elevation of saturated fatty acids such as myristic, stearic arachidic and lignoceric acids. Palmitic acid was unchanged in females and only slightly altered in males. Unsaturated fatty acids from total phospholipids were discretely increased, including linoleic, linolenic, arachidonic, eicosapentaenoic, docosapentaenoic and docosahexaenoic acids. Total fatty acid content of phosphatidylcholine and phosphatidylethanolamine fractions were also increased in relation to age in both sexes. The unsaturated components, however, showed a larger proportional increase. Major acyl components involved in these age-related changes were significantly increased, including linolenic and arachidonic acids; palmitic and docosahexaenoic acids were decreased. These data indicate that in rat hepatic phospholipids a selective increase in unsaturated fatty acids predominated during development with profound influences in the subcellular distribution of these moieties.

Aging↗

PubMed2005

Concerning the origin of 19F-19F NMR COSY and NOESY connections in the spectra of perfluorooctanoic acid, R(F)-palmitic acid-F13 and diethyl perfluorosuberate.

A combination of 19F nuclear Overhauser effects (NOE) and molecular mechanics calculations are presented for delineating the spatial origin of the well-known four-bond 19F-19F COSY connections which are generally observed in the 19F NMR spectra of compounds containing perfluorinated chains. Perfluorooctanoic acid (PFOA), R(F)-palmitic acid-F13 and diethyl perfluorosuberate were used as test cases. Spin-lattice relaxation times (T1) are included and NOESY correlations through three and four bonds occur.

Algorithms↗

PubMed2005

Conjugated linoleic acid suppresses the secretion of atherogenic lipoproteins from human HepG2 liver cells.

Studies in healthy humans have shown that consumption of conjugated linoleic acid (CLA) significantly reduced very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) blood concentrations. We propose that decreased concentrations are due to the inhibition of VLDL production and secretion [measured by apolipoprotein B100 (apoB100)] from the liver. To investigate the effects of a mixture of CLA isomers on VLDL metabolism, HepG2 liver cells were incubated for 24 h with 50 micromol/L of the different fatty acids. Effects of CLA were compared to a saturated fatty acid (palmitic acid), an n-6 fatty acid (linoleic acid) and no treatment (control). HepG2-cell apoB100 levels were measured using Western blotting. ApoB100 secretion was significantly decreased in cells treated with CLA (44%, p<0.005) compared to control cells and those enriched with palmitic acid. Treatment of cells with CLA also decreased intracellular cholesterol levels. Collectively, these results demonstrate that CLA reduces apoB100 production and secretion compared to saturated and polyunsaturated fatty acids, possibly by limiting the availability of free cholesterol (required for apoB100 production). A reduction in apoB100 production in the body would decrease the levels of VLDL and atherogenic LDL and thus reduce the risk of developing cardiovascular disease.

Apolipoprotein B-100↗

PubMed2006

Saturated fatty acids inhibit induction of insulin gene transcription by JNK-mediated phosphorylation of insulin-receptor substrates.

JNKs are attractive targets for treatment of obesity and type-2 diabetes. A sustained increase in JNK activity was observed in dietary and genetic models of obesity in mice, whereas JNK deficiency prevented obesity-induced insulin resistance. A similar insulin-sensitizing effect was seen upon treatment of obese mice with JNK inhibitors. We now demonstrate that treatment with the saturated fatty acid palmitic acid results in sustained JNK activation and insulin resistance in primary mouse hepatocytes and pancreatic beta-cells. In the latter, palmitic acid treatment inhibits glucose-induced insulin gene transcription, in part, by interfering with autocrine insulin signaling through phosphorylation of insulin-receptor substrates 1 and 2 at sites that interfere with binding to activated insulin receptors. This mechanism may account for the induction of central insulin resistance by free fatty acids.

Amino Acid Sequence↗

PubMed2003

Activity and mRNA levels of enzymes involved in hepatic fatty acid synthesis and oxidation in mice fed conjugated linoleic acid.

The effects of dietary conjugated linoleic acid (CLA) on the activity and mRNA levels of hepatic enzymes involved in fatty acid synthesis and oxidation were examined in mice. In the first experiment, male ICR and C57BL/6J mice were fed diets containing either a 1.5% fatty acid preparation rich in CLA or a preparation rich in linoleic acid. In the second experiment, male ICR mice were fed diets containing either 1.5% linoleic acid, palmitic acid or the CLA preparation. After 21 days, CLA relative to linoleic acid greatly decreased white adipose tissue mass but caused hepatomegaly accompanying an approximate 10-fold increase in the tissue triacylglycerol content irrespective of mouse strain. CLA compared to linoleic acid greatly increased the activity and mRNA levels of various lipogenic enzymes in both experiments. Moreover, CLA increased the mRNA expression of Delta6- and Delta5-desaturases, and sterol regulatory element binding protein-1 (SREBP-1). The mitochondrial and peroxisomal palmitoyl-CoA oxidation rate was about 2.5-fold higher in mice fed CLA than in those fed linoleic acid in both experiments. The increase was associated with the up-regulation of the activity and mRNA expression of various fatty acid oxidation enzymes. The palmitic acid diet compared to the linoleic acid diet was rather ineffective in modulating the hepatic lipid levels or activity and mRNA levels of enzymes in fatty acid metabolism. It is apparent that dietary CLA concomitantly increases the activity and mRNA levels of enzymes involved in fatty acid synthesis and oxidation, and desaturation of polyunsaturated fatty acid in the mouse liver. Both the activation of peroxisomal proliferator alpha and up-regulation of SREBP-1 may be responsible for this.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1987

Fatty Acid Specificity and Selectivity of the Chloroplast sn-Glycerol 3-Phosphate Acyltransferase of the Chilling Sensitive Plant, Amaranthus lividus.

Chilling sensitivity of plants is strongly correlated with the presence of high levels of a species of chloroplast phosphatidylglycerol that contains two saturated fatty acids. The most straightforward synthetic pathway for this lipid would require the primary acylation of sn-glycerol 3-phosphate (G3P) with a saturated fatty acid (palmitic acid) rather than with oleic acid, an unsaturated acid. This selective incorporation would differ markedly from the reported properties of the chloroplast G3P acyltransferases of pea and spinach, two chilling resistant plants and thus we have studied the chloroplast G3P acyltransferase of Amaranthus lividus, a chilling sensitive plant. In contrast to our results and those of others (M. Frentzen et al. 1983 Eur J Biochem 129: 629-636 and previous work) with the pea and spinach enzymes, the amaranthus chloroplast G3P acyltranferase did not select oleic acid donors from a mixture of oleic and palmitic acid donors (either coenzyme A or acyl carrier protein thioesters). Instead the fatty acid composition of the synthesized 1-acyl G3P faithfully reflected the composition of the acyl donor mixture. However, the amaranthus enzyme did strongly select against incorporation of stearic acid. The properties of the amaranthus G3P acyltransferase are consistent with this enzyme having the major role in synthesis of the disaturated phosphatidylglycerol species.

Journal Article↗

PubMed1993

Expression of rabbit cytochromes P4504A which catalyze the omega-hydroxylation of arachidonic acid, fatty acids, and prostaglandins.

The omega-hydroxylation product of arachidonic acid is thought to be a potent vasoconstrictor or a precursor thereof in kidney. In this report, we have measured the capacity of four rabbit CYP4A enzymes, each expressed in COS-1 cells, to catalyze the omega-hydroxylation of arachidonic acid. These rates were compared to those obtained for other substrates such as lauric acid, palmitic acid, and prostaglandins PGE1 and PGA1. With the exception of P4504A5, all of the enzymes tested exhibited relatively high rates for the omega-hydroxylation of arachidonic acid. P4504A5 showed very little activity toward arachidonic or palmitic acids as compared to that toward lauric acid (< 10%). In contrast, P4504A6 and P4504A7 catalyzed the omega-hydroxylation of arachidonic acid at rates that were roughly 50% of that observed for lauric acid. P4504A4 was not active toward lauric acid, but it also catalyzed the omega-hydroxylation of arachidonic acid at a rate that was roughly 20% of that exhibited for PGE1. Thus, each enzyme exhibits a distinct substrate specificity profile across this panel of substrates. A sensitive RNase protection assay was used to provide a more quantitative estimate of the relative abundance of mRNAs encoding P4504A5, P4504A6, and P4504A7 in liver and kidney from control, pregnant, and clofibrate-treated animals. CYP4A5 is the most abundant of the mRNAs, but it was not induced in kidney and only moderately (2-fold) in liver by clofibric acid. CYP4A7 exhibits a similar pattern of induction by clofibrate. In contrast, CYP4A6 is induced 12-fold in liver and 6-fold in kidney. The higher induction ratio largely reflects a lower basal level of expression for CYP4A6 than for CYP4A7 and CYP4A5. Following treatment with clofibrate, the amount of CYP4A6 mRNA is similar to those of CYP4A5 and CYP4A7. Pregnancy did not affect the expression of CYP4A5, CYP4A6, or CYP4A7, although it induced the expression of CYP4A4 to detectable levels in the liver and kidney, where it is not normally found in nonpregnant animals. Our results indicate that the enzyme whose mRNA is most highly induced by clofibric acid (P4504A6) and the enzyme selectively elevated during pregnancy (P4504A4) both exhibit relatively high rates for the omega-hydroxylation of arachidonic acid.

Animals↗

PubMed1992

[Differentiation of fattening and slaughtering performance and carcass quality of broiler genotypes with and without the dwarf factor and fast or slow feathering under heat stress].

In a comparative study the influences were tested of the origins NWR (normal-growth White Rocks) and ZWR (dwarf-growth White Rocks) with a speed for slow (K) and fast (k) feathering as well as the effect of a high environmental temperature (UT, 32 +/- 2.5 degrees C) on the fattening and slaughtering performance of male broilers and their meat quality. Also investigated were effects of these factors on the fatty acid pattern of the two valuable parts--breast and leg. Dwarf broilers kept under high UT had a lower liveweight (LM8) in their 8th week as compared with NWR and animals kept under the usual UT. No influence was found of the feathering on the fattening and slaughtering performance. The effect of heat stress (high UT) and of the dwarfing gene on the breast and leg parts was statistically highly significant (P < 0.001). Dwarfed broilers and animals under normal UT exhibited a smaller slaughtering proportion as compared with normal animals and animals under a higher UT. The abdominal fat content was significantly higher under heat stress. Meat quality showed no dependence on the origin or the climatic conditions. In the fatty acid analysis no dependence could be detected of the FS pattern on the origins (genotypes), whereas an effect was found of the UT on some unsaturated and saturated fatty acids. Palmitic acid and stearic acid formed the largest part of all saturated FS investigated. Among the unsaturated FS the oil, linoleic, and palmitic acids reached the highest share. The effect of higher UT was not uniform in the FS pattern. The sum of saturated FT was increased under heat stress, thus suggesting a more favourable fat quality of the meat.

Adipose Tissue↗

PubMed1986

Mitochondrial Ca2+ fluxes: role of free fatty acids, acyl-CoA and acylcarnitine.

It has been suggested that accumulation of lipid metabolites, such as fatty acids, fatty acyl-CoA and acylcarnitine, in the ischaemic myocardium, may be responsible for disturbances in mitochondrial Ca2+ fluxes. In view of the presence of an intracellular fatty acid binding protein, the question arose whether these intermediates affect mitochondrial Ca2+ uptake and release similarly in vivo. In this study the effects of linoleic acid, palmitic acid, palmitoyl-CoA and palmitoylcarnitine were studied on mitochondrial Ca2+ fluxes in the absence and presence of albumin, an avid binder of fatty acid derivatives. Albumin reversed the effects of the above compounds on mitochondrial Ca2+ uptake and release, suggesting that the presence of an intracellular fatty acid binding protein may protect the ischaemic myocardial cell against the deleterious effects of accumulated fatty acid derivatives.

Acyl Coenzyme A↗

PubMed1986

Effect of monensin and nocodazole on the intestinal lipid esterification in mouse jejunal organ culture.

The ability of mouse jejunal explants to esterify a lipid emulsion containing oleic acid, palmitic acid and monopalmitin has been studied in different in vitro experimental conditions. The incubating lipid solution must have a minimum volume for obtaining optimal triglyceride esterification by the cultured intestinal mucosa. In our incubating conditions the exchange of oleic for palmitic acid does not significantly modify the amount of lipids esterified by the explants in 15 min. Monensin or nocodazole, added to the culture medium of intestinal explants for 3 hr, significantly change the amount of lipids esterified and secreted. The inhibition observed after nocodazole treatment disappears, however, when the explants are rinsed and the culture is allowed to continue for an additional 3 hr in a drug-free medium. These results suggest that the regulation of lipid metabolism can be studied in organ culture.

Animals↗

PubMed1981

Suppression of IgE antibody response by the fatty acid-modified antigen.

Ovalbumin (OA) of hens was chemically coupled with fatty acids (lauric acid, myristic acid, palmitic acid and stearic acid). These hydrophobically modified antigens were unable to react with mouse antiserum against native OA and were incapable of eliciting primary and secondary anti-OA antibody responses in BALB/c mice. Preadministration of these modified antigens, especially of palmitoyl OA (OA-pal), suppressed both primary and secondary anti-OA IgE antibody responses without affecting IgG antibody production. Administration of OA-pal after the primary immunization resulted in a rapid decrease of the ongoing anti-OA IgE antibody production and inhibited the anamnestic anti-OA IgE antibody response upon subsequent immunization with OA. The passive transfer of spleen cells from OA-pal-treated animals with OA-primed spleen cells suppressed the adoptive secondary anti-OA IgE antibody response in irradiated recipients. The suppressive effect was abrogated by treatment with an anti-T-cell antiserum indicating that suppressor T cells were primed by administration of hydrophobically modified antigens.

Animals↗

PubMed1996

Influence of lipid chain unsaturation on melittin-induced micellization.

It is well known that melittin, an amphipathic helical peptide, causes the micellization of phosphatidylcholine vesicles. In the present work, we conclude that the extent of micellization is dependent on the level of unsaturation of the lipid acyl chains. We report the results obtained on two systems: dipalmitoylphosphatidylcholine (DPPC), containing 10(mol)% saturated or unsaturated fatty acid (palmitic, oleic, or linoleic), and DPPC, containing 10(mol)% positively charged diacyloxy-3-(trimethylammonio)propane bearing palmitic or oleic acyl chains. For both systems, the presence of unsaturation in the lipid acyl chains inhibits melittin-induced micellization. Conversely, the addition of saturated palmitic acid to the DPPC matrix enhances the micellization. This modulation is proposed to be associated with the cohesion of the hydrophobic core. When the lipid chain packing of the gel-phase bilayer is already perturbed by the presence of unsaturation, it seems easier for the membrane to accommodate melittin at the interface, and the distribution of the peptide in the bilayer could be the origin of the inhibition of the micellization. The cohesion of the apolar core is shown to play an unquestionable role in melittin-induced micellization; however, this contribution does not appear to be as important as the electrostatic interactions between melittin and positively or negatively charged lipids.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2006

Effects of fatty acids on skeletal muscle cell differentiation in vitro.

Previous studies have shown stimulatory effects of linoleic acid (LA, C18:2) on differentiation of rat muscle cells in culture (Allen et al. 1985), but there appears to be little investigation of the effects of other fatty acids. The present study therefore compared the effects of different fatty acids on muscle cell differentiation in vitro. L6 myoblasts were cultured (Dulbecco's Modified Eagles Medium + 10 % fetal calf serum) in six-well plates until 80 % confluent (day 0). Cells were then either harvested or the medium switched to differentiation medium (Dulbecco's Modified Eagles Medium+2 % horse serum), supplemented with fatty acid or drug treatments. Cells were harvested on days 0-5 and assayed for creatine kinase (CK), protein and DNA contents, to give a measure of differentiation (CK/DNA). Initial studies indicated a stimulatory effect of the cis9,trans11 (c9,t11) isomer of conjugated linoleic acid (CLA) relative to control. By contrast, the trans10,cis12 (t10,c12) isomer of CLA inhibited differentiation. Further experiments indicated that inhibition of differentiation by the t10,c12 CLA isomer was dose-dependent (up to 200 microm) and may be via increased cell proliferation. LA and c9,t11 CLA stimulated differentiation at low concentrations (up to 50 microm), but inhibited differentiation at high concentrations (200 microm). In contrast, oleic acid stimulated differentiation at all concentrations, whereas the saturated fatty acid, palmitic acid, had no effect. The mechanism appeared not to involve either peroxisome proliferator-activated receptors alpha or gamma. The data suggest that only unsaturated fatty acids have an effect and the presence or absence of a cis-9 double bond may be important.

Animals↗

PubMed1972

Composition of fatty acids and carbohydrates in Leptospira.

The fatty acid and monosaccharide composition of four pathogenic and two saprophytic strains of Leptospira was analyzed by gas chromatography (GC) and GC-mass spectrometry. Among the fatty acids, palmitic acid was most abundant and constituted 30 to 50% of the total fatty acids. Even-numbered unsaturated acids including octadecenoic, hexadecenoic, octadecadienoic, and tetradecadienoic acids comprised 40 to 60% of the total fatty acids. Tetradecanoic acid was about 5% in saprophytic strains, but 1% or less in pathogenic strains. The amount of chloroform-methanol extract of L. biflexa strain Ancona was 14 to 20% of the dry weight of the cell. Tetradecadienoic acid was found in the chloroform-methanol insoluble fraction, suggesting the presence of the acid in a bound form. GC analysis of monosaccharides revealed the existence of arabinose, xylose, rhamnose, mannose, galactose, glucose, glucosamine, and muramic acid in the cells. Among the neutral sugars, glucose was a minor component and was especially low in pathogenic strains. Total pentose content was about two to three times greater than total hexose.

Amino Sugars↗

PubMed1979

Circadian rhythms in Neurospora crassa: effects of unsaturated fatty acids.

Employing a fatty acid-requiring strain (bd csp cel) of Neurospora crassa, the 21.5-h period of the circadian spore-forming rhythm was manipulated by fatty acid supplementation. The addition to the medium of an unsaturated fatty acid (oleic, linoleic, or linolenic acid) lengthened the period to 26, 40, or 33 h, respectively. Ther period-lengthening effect of linoleic acid was proportional to its concentration up to 1.3 X 10(-4) M, and also was reversed by the addition to the medium of a saturated fatty acid, palmitic acid. None of these period-lengthening effects was observed in the prototrophic strain (bd csp cel+).

Circadian Rhythm↗

PubMed2006

Characteristic long-chain fatty acid of Pleurocybella porrigens.

As part of an investigation on the chemical constituents and contaminants of the basidiomycete Pleurocybella porrigens (Japanese name: Sugihiratake), we analyzed the UV-detected constituents of this mushroom using HPLC. One of the major UV peaks detected was isolated and identified as a-eleostearic acid, a long-chain fatty acid with a conjugated triene moiety, based on the results of spectroscopic methods. alpha-Eleostearic acid was concluded to be a characteristic fatty acid of P. porrigens, because it was not detected in eight other edible mushrooms examined. Free long-chain fatty acids in P. porrigens and other edible mushrooms were analyzed by HPLC after derivatization with acidic 2-nitrophenylhydrazine hydrochloride. Oleic acid was the main fatty acid in P. porrigens, and saturated long-chain fatty acids such as linoleic acid, palmitic acid, and stearic acid, together with a-eleostearic acid, were also detected.

Agaricales↗