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PubMed2006

Kinetic studies of the interaction of fatty acids with phosphatidylcholine vesicles (liposomes).

The kinetics of addition of fatty acids (as alkaline solutions of the fatty acid anions) to pre-existing unilamellar phospholipid vesicles (mean diameter 100 nm) has been studied. The phospholipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) has been mainly used, together with three fatty acids, oleic acid (cis-9-octadecenoic acid), linoleic acid (cis,cis-9,12-octadecadienoic acid) and capric acid (decanoic acid). Experiments were performed above as well as below the main phase transition temperature (Tm) of DMPC vesicles. The pH chosen to study the fatty acid vesicle interaction (after fatty acid and vesicle mixing) was 8.5 in the case of oleic acid and linoleic acid and 7.4 for capric acid. In the absence of any pre-existing phospholipid vesicles, the addition of alkaline solutions of the fatty acid anions to corresponding buffer solutions of pH 8.5 or 7.4 leads to a partial protonation of the fatty acid anions again resulting in the formation of fatty acid vesicles. This process is rather slow, taking place over a period of hours/days, and the vesicles formed are very polydisperse and include a range of vesicle sizes/shapes. However, in the presence of pre-existing phospholipid vesicles the added fatty acids equilibrate readily within a few minutes and the size of the vesicles that form are then closely related to the size of the originally present phospholipid vesicles; the vesicles formed being generally somewhat larger than the pre-existing vesicles. In the case of the phospholipid DMPC, the mixed fatty acid/phospholipid vesicle system is often formed rather rapidly (particularly above Tm), so that stopped-flow methods have been applied to follow the kinetics of the process. It is proposed that most of the fatty acid molecules are initially rapidly incorporated into the bilayers of the pre-exisiting phospholipid vesicles as monomers, rather than that the added fatty acids form separate fatty acid vesicles. The mean vesicle sizes formed in the systems investigated have been analysed by using dynamic light scattering measurements. The behaviour of the DMPC system was found to be slightly different from the POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) system studied before, but the results are consistent with a model that involves growth and subsequent fission of the mixed vesicles. The study provides further support of the "matrix effect" in this type of system [S. Lonchin, P.L. Luisi, P. Walde, B.H. Robinson, J. Phys. Chem. B 103 (1999) 10910-10916]. The pre-existing DMPC vesicles act as a kind of seed to control the behavior of the system in the presence of added fatty acid anions.

Buffers↗
PubMed1977

Morphological differentiation of neuroblastoma cells in medium supplemented with delipidated serum.

Neuroblastoma cells have been found to extend neurites when grown in a medium supplemented with delipidated fetal calf serum. Fetal calf sera from different commercial sources give rise to marked differences in the degree of this spontaneous morphological differentiation. The phenomenon can be prevented by the addition of certain fatty acids; oleic acid is especially effective. The serum-free conditioned medium from glial cells can quantitatively antagonize the effect of oleic acid, suggesting that glial factor activity could be due to components [lipids and/or macromolecular factors(s)] that are able to modify the properties of the neuroblastoma cell membrane.

Blood↗
PubMed1976

The effects of long chain free fatty acids on human neutrophil function and structure.

Neutrophils from healthy volunteers were isolated and incubated with varying concentrations of albumin-bound long chain free fatty acids. Standard in vitro function tests including phagocytosis, bactericidal activity, and chemotaxis were performed after the incubation. It was found that unsaturated fatty acid (oleic acid) caused no changes in bactericidal activity and only moderate decreases in phagocytosis and chemotaxis at very high concentrations. Saturated fatty acid (palmitic acid) produced, at high concentrations, virtually complete inhibition of chemotaxis and moderate depression of phagocytosis and bactericidal ability. Most significantly, lower concentrations of saturated free fatty acids, within the range reported clinically in various diseases, caused a marked inhibition of chemotaxis. These functional disturbances were associated with ultrastructural alterations. Neutrophils treated with oleic acid contained numerous cytoplasmic neutral lipid droplets. Neutrophils incubated with palmitic acid showed elongated cleftlike dilations of the endoplasmic reticulum and degenerative degranulated cytoplasmic areas. It is postulated that these represent crystallization of excess saturated free fatty acids or triglyceride which interfere with chemotaxis, either mechanically or by causing cell injury.

Blood Bactericidal Activity↗
PubMed2005

Fatty acid-induced changes in vascular reactivity in healthy adult rats.

Dietary fatty acids (FAs) are known to modulate endothelial dysfunction, which is the first stage of atherosclerosis. However, their exact role in this initial phase is still unclear. The effects of isolated or combined (by 2) purified FAs from the main FA families were studied on the vascular response of isolated thoracic aorta in healthy rats to get a better understanding of the mechanisms of action of dietary FAs in regulating vascular endothelial function. Cumulative contraction curves to phenylephrine and relaxation curves to carbachol and then to sodium nitroprusside were obtained in the absence or presence of the FAs studied allowing endothelium-dependent and endothelium-independent ability of the smooth muscle to relax to be assessed in each experimental group. The endothelium-dependent vasodilator response to carbachol was lowered by eicosapentaenoic acid, whereas it was not altered either by docosahexaenoic acid alone or by combined eicosapentaenoic acid-docosahexaenoic acid, oleic acid, or stearic acid, and it was increased by linoleic acid (LA). A decreased phenylephrine-induced contraction was observed after incubation with arachidonic acid and with stearic acid. On the other hand, the endothelium-dependent relaxation was reduced by the addition of combined LA-arachidonic acid and LA-oleic acid. In conclusion, these data point out the differential effects of different types of FAs and of FAs alone vs combined on vascular reactivity. The complex nature of these effects could be partially linked to metabolic specificities of endothelial cells and to interactions between some FAs.

Animals↗
PubMed1985

Metabolic fate of liposomal phosphatidylinositol in murine tumor cells: implications for the mechanism of tumor cell cytotoxicity.

The mechanism of the previously reported cytotoxicity of liposomes containing plant phosphatidylinositol (PI) against numerous tumor cell lines was examined in detail by using liposomes containing synthetic PI specifically labeled either with radioactive myo-inositol, or in the sn-2 position with radioactive linoleic acid, oleic acid, or arachidonic acid. The uptake of liposomal PI by N4TG1 neuroblastoma cells increased with time and was dependent on the nature of the fatty acids. Uptake was highest with liposomal PI containing linoleic acid followed by arachidonic acid and then by oleic acid. The cellular fate of liposomal PI was determined by analysis of radioactive metabolites present in extracts of tumor cell lipids. Appearance of liposomal PI metabolic products in the tumor cells was correlated with thymidine uptake as a measure of viability. After 3 h incubation of cells with PI liposomes it was found that the release of both radioactive liposomal fatty acids (and probably also lyso-Pl) and radioactive diglycerides was correlated inversely with the cellular uptake of [methyl-3H]thymidine and uptake of [3H]myoinositol. An experiment in which liposomes were prepared both from animal Pl which contained predominantly saturated fatty acids in the sn-2 position and an increasing mole fraction of a synthetic Pl containing radioactive linoleic acid in the sn-2 position established that the amount of Pl containing linoleic acid in the sn-2 position could be correlated with a decrease in the amount of thymidine uptake by tumor cells. The above results clearly established that phospholipases A2 and C in the tumor cells were responsible for the formation of metabolites of liposomal Pl, and these metabolic products might have been responsible for cytotoxicity and cell death.

Animals↗
PubMed1999

Tetradecylthioacetic acid (a 3-thia fatty acid) impairs secretion of oleic acid-induced triacylglycerol-rich lipoproteins in CaCo-2 cells.

The fatty acid analogue tetradecylthioacetic acid (TTA) has previously been shown to decrease triacylglycerol secretion in CaCo-2 cells (Gedde-Dahl et al., J. Lipid Res. 36 (1995) 535-543). The present study was designed to further elucidate the effect of TTA on lipoprotein production in CaCo-2 cells. TTA did not affect oleic acid-induced triacylglycerol synthesis, but it significantly decreased secretion of newly synthesized triacylglycerol when compared to cells incubated with oleic acid alone or oleic acid in combination with palmitic acid. In contrast, pulse-chase experiments showed no difference in the amount of labeled triacylglycerol secreted from cells exposed to either fatty acid combination during the chase period, indicating that TTA did not affect the secretory process in general. Cells incubated with TTA alone secreted triacylglycerol present at 1.025<rho<1.073 g/ml, corresponding to the low density lipoprotein/intermediate density lipoprotein density range. In contrast, cells supplemented with oleic acid or oleic acid in combination with TTA secreted triacylglycerol mainly in the very low density lipoprotein/chylomicron density range (rho<1.006 g/ml). Despite a marked decrease in triacylglycerol secretion, TTA treatment did not change secretion of apolipoprotein B nor the activity of microsomal triacylglycerol transfer protein (MTP) in the cells. Furthermore, the presence of TTA in cellular triacylglycerol had no effect on the ability of purified MTP to transfer triacylglycerol from donor to acceptor vesicles. Together, the above observations suggest that TTA interferes with other MTP-independent factors that regulate the intestinal lipoprotein secretion.

Acyltransferases↗
PubMed1988

Modification of the fatty acid composition of L1210 leukemia subcellular organelles.

We have examined the extent to which it is possible to modify the fatty acid composition of subcellular organelles of L1210 leukemia cells. A polyunsaturated fatty acid, docosahexaenoic acid, or a monounsaturated fatty acid, oleic acid, were added to the culture media. After 48 hr, the cells were ruptured and the subcellular fractions isolated. Fatty acid analysis revealed that nuclei, mitochondria, plasma membranes and microsomes of the cells grown in media supplemented with docosahexaenoic acid contained increased amounts of polyenoic fatty acids compared with cells grown in oleic acid. We conclude that it is possible to experimentally modify the lipids of multiple intracellular structures of L1210 cells by the addition of fatty acids to the growth media.

Animals↗
PubMed2004

Differential regulation by fatty acids of protein histidine phosphorylation in rat pancreatic islets.

Long-chain fatty acids (e.g. arachidonic acid) have been implicated in physiological control of insulin secretion. We previously reported histidine phosphorylation of at least two islet proteins (e.g., NDP kinase and the beta subunit of trimeric G-proteins), and suggested that such a signalling step may have regulatory roles in beta cell signal transduction, specifically at the level of G-protein activation. Since our earlier findings also indicated potential regulation by long-chain fatty acids of islet G-proteins, we undertook the current study to verify putative regulation, by fatty acids, of protein histidine phosphorylation of NDP kinase and Gbeta subunit in normal rat islets. The phosphoenzyme formation of NDP kinase was stimulated by various fatty acids in the following rank order: linoleic acid > arachidonic acid > oleic acid > palmitic acid = stearic acid = control. Furthermore, the catalytic activity of NDP kinase was stimulated by these fatty acids in the rank order of: oleic acid > arachidonic acid > linoleic acid > palmitic acid = stearic acid = control. Arachidonic acid methyl ester, an inactive analog of arachidonic acid, did not significantly affect either the phosphoenzyme formation or the catalytic activity of NDP kinase. Interestingly, arachidonic acid exerted dual effects on the histidine phosphorylation of beta subunit; it significantly stimulated the phosphorylation at 33 microM beyond which it was inhibitory. Together, these findings identify additional loci (e.g., NDP kinase and Gbeta subunit) at which unsaturated, but not saturated, fatty acids could exert their intracellular effects leading to exocytotic secretion of insulin.

Animals↗
PubMed1982

Fatty acid effects on calcium influx and efflux in sarcoplasmic reticulum vesicles from rabbit skeletal muscle.

Low concentrations of fatty acids inhibited initial Ca uptake by sarcoplasmic reticulum vesicles, the extent of inhibition varying with chain length and unsaturation in a series of C14-C20 fatty acids. Oleic acid was a more potent inhibitor of initial Ca uptake than stearic acid at 25 degrees C, whereas at 5 degrees C there was less difference between the inhibitory effects of low concentrations of these fatty acids. When the fatty acids were added later, during the phase of spontaneous Ca release that follow Ca uptake in reactions carried out at 25 degrees C 1-4 microM oleic and stearic acids caused Ca content to increase. This effect was due to marked inhibition of Ca efflux and slight stimulation of Ca influx. At concentrations of greater than 4 microM, both fatty acids inhibited the Ca influx that occurs during spontaneous Ca release; in the case of oleic acid, this inhibition resembled that of initial Ca uptake at 5 degrees C. The different effects of fatty acids at various times during Ca uptake reactions may be explained in part if alterations in the physical state of the membranes occur during the transition from the phase of initial Ca uptake to that of spontaneous Ca release.

Animals↗
PubMed1984

The dynamics of lipid motion in sarcoplasmic reticulum membranes determined by steady-state and time-resolved fluorescence measurements on 1,6-diphenyl-1,3,5-hexatriene and related molecules.

Steady-state and time-resolved fluorescence anisotropy measurements were made on 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 1-acyl-2-(DPH)-phosphatidylcholine (DPH-PC) incorporated into sarcoplasmic reticulum membranes. The results were analysed in terms of the 'wobbling-in-cone' model. Considerable differences in the fluorescence parameters were found. In particular TMA-DPH and DPH-PC showed a smaller cone angle, relating to the range of acyl chain motion, compared to DPH, taken to be a reflection of a difference in probe locations. The influence of the protein component was also found to restrict DPH motion more than TMA-DPH and DPH-PC. Effectiveness in assessment of perturbation of the membrane by the non-esterified fatty acid, oleic acid again revealed differences. The steady-state anisotropy decreased on addition of oleic acid; a recovery to control values was observed with DPH but not with the other probes. Time-resolved parameters followed the same pattern. The results of this work demonstrated the effectiveness of these three probes in revealing differences in membrane properties, such as protein and fatty acid perturbation of membrane lipid structure and dynamics.

Animals↗
PubMed1993

[The effect of palmitic, oleic and linoleic acids on thermogenesis in the model experiment in sows].

An animal model experiment was conducted with nine adult sows to study the effects of long-chain fatty acids on thermogenesis when different fatty acids were replaced for 30% of the energy of a basal diet based on cereals and soybean meal. The acids were fed as commercial products containing as main constituent either palmitic acid, oleic acid, or linoleic acid, according to a latin square design in experimental periods 2 to 4. In periods 1 and 5 the sows were submitted to basal diet alone. Digestibility of palmitic acid was only 36%, whereas the unsaturated fatty acids were highly absorbed (90%). Interaction effects of the undigested proportion of the long-chain fatty acids with the basal diet in hindgut fermentation could be ruled out since a supplementary experiment on three sows showed no influence of infusion of oleic or linoleic acid into the caecum on the energy utilization of the basal diet. There was no significant differences in thermogenesis among the fatty acids. Heat production in the treatment periods averaged -1.2% as compared to the basal diet periods. This result was in accordance with the value -1.0% calculated theoretically for the reduction in heat production in the treatment periods. Thus, the data did not indicate any stimulating effect of long-chain fatty acids on heat production, and utilization of energy of fatty acids occurred within the obligatory thermogenesis.

Absorption↗
PubMed2002

Effect of eicosapentaenoic acid ethyl ester v. oleic acid-rich safflower oil on insulin resistance in type 2 diabetic model rats with hypertriacylglycerolaemia.

The purpose of the present study was to test whether hyperlipidaemia and insulin resistance in type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats can be improved by dietary supplementation with purified eicosapentaenoic acid (EPA) or oleic acid (OA). Male OLETF rats were fed powdered chow (510 g fat/kg) alone (n 8) or chow supplemented with 10 g EPA- (n 8) or OA- (n 8) rich oil/kg per d from 5 weeks until 30 weeks of age. An oral glucose tolerance test and hyperinsulinaemic euglycaemic clamp was performed at 25 and 30 weeks of age. EPA supplementation resulted in significantly (P<0.05) reduced plasma lipids, hepatic triacylglycerols, and abdominal fat deposits, and more efficient in vivo glucose disposal compared with OA supplementation and no supplementation. OA supplementation was associated with significantly increased insulin response to oral glucose compared with EPA supplementation and no supplementation. Inverse correlation was noted between glucose uptake and plasma triacylglycerol levels (r -086, P<0.001) and abdominal fat volume (r -0.80, P<0.001). The result of oral glucose tolerance test study showed that the rats fed EPA tended to improve glucose intolerance, although this was not statistically significant. Levels of plasma insulin at 60 min after glucose was significantly increased in rats fed OA compared with the other two groups. The results indicate that long-term feeding of EPA might be effective in preventing insulin resistance in diabetes-prone rats, at least in part, due to improving hypertriacylglycerolaemia.

Abdomen↗
PubMed2000

Structured lipids improve fat absorption in normal and malabsorbing rats.

The presence of medium-chain fatty acids in dietary fatty acid as well as the triacylglycerol structure may influence the absorption and lymphatic transport of fatty acids. We compared the lymphatic transport and recovery of fatty acids from four intragastrically administered fats based on rapeseed oil and decanoic acid in two rat models of normal absorption and malabsorption, respectively. The fats were: 1) a fat with a regiospecific structure, 2) a similar fat but with a random distribution of fatty acids in the triacylglycerol molecule, 3) a physical mixture of tridecanoin and rapeseed oil and 4) rapeseed oil as control. Lymph samples were collected for 24 h. Significantly higher recoveries were observed of total fatty acids, oleic acid, linoleic acid and linolenic acid from the specific oil in malabsorbing rats and of linoleic acid in normal rats fed specific oil compared with those fed rapeseed oil. Furthermore, the recoveries of oleic acid and linolenic acid from the specific oil in normal rats were higher than those from the other oils. In malabsorbing rats, the transport of all fats was approximately 90% less than that of normal rats. The present study demonstrates improved hydrolysis and absorption of the specific oil compared with the other oils examined both in rats with normal absorption and in rats with malabsorption.

Analysis of Variance↗
PubMed2005

Effects of fatty acids on growth and poly-3-hydroxybutyrate production in bacteria.

The effects of saturated and unsaturated fatty acids (lauric acid, palmitic acid, steric acid, oleic acid, linoleic acid, soybean oil) on Sphaerotilus natans, 0B17 (Pseudomonas sp.), and recombinant Escherichia coli DH5(/pUC19/CAB were studied. Oleic acid enhances Poly-3-hydroxybutyrate (PHB) production in these three bacterial strains, suggesting that the single double bond of the acid activates the polyhydroxylkanoate accumulation enzymatic reaction. Under the effect of lauric acid and linoleic acid, the growth of S. natans and 0B17 were totally inhibited. However, the enhanced PHB accumulation in recombinant E. coli was observed.

Bioreactors↗
PubMed1994

Synthesis of trans unsaturated fatty acids in Pseudomonas putida P8 by direct isomerization of the double bond of lipids.

The phospholipids of Pseudomonas putida P8 contain monounsaturated fatty acids in the cis and trans configuration. Cells of this phenol-degrading bacterium change the proportions of these isomers in response to the addition or elimination of a membrane active compound such as 4-chlorophenol. This study undoubtedly reveals that the cis unsaturated fatty acids are directly converted into trans isomers without involvement of de novo synthesis of fatty acids. Oleic acid, which cannot be synthesized by this bacterium, was incorporated as a cis unsaturated fatty acid marker in the membrane lipids of growing cells. The conversion of this fatty acid into the corresponding trans isomer was demonstrated by gas chromatographic-mass spectrometric analysis and use of 14C-labeled oleic acid. Separation and isolation of the cellular membranes showed that the fatty acid isomerase is located in the cytoplasmic membrane of P. putida P8.

Carbohydrate Sequence↗
PubMed1994

Effect of essential fatty acid deficiency on the fatty acid composition and arachidonic acid levels in rat maxillae and mandibles.

The fatty acid composition of total lipids and total phospholipids of maxillae and mandibles of rats fed an essential fatty acid-deficient (EFAD), marginally FAD (MEFAD), and a control diet was determined. Patterns typical of an EFA deficiency such as a decrease in the levels of linoleic acid and archidonic acid along with concomitant increase in the levels of palmitoleic acid, oleic acid, and 5,8,11-eicosatrienoic acid were observed in the EFAD groups. Concentrations of arachidonic acid were significantly lower in total lipids of mandibles and maxillae of rats in the EFAD, but not in the MEFAD rats, than those of the controls.

Animals↗
PubMed1991

New substrates of the multispecific bile acid transporter in liver cells: interference of some linear renin inhibiting peptides with transport protein(s) for bile acids.

Interactions between some stable linear peptides with renin inhibitory activity and a multispecific transport system in the basolateral plasma membrane of liver cells was studied on cell suspensions. The peptides used in our experiments were taken up by liver cells and subsequently eliminated without any biotransformation (e.g., proteolysis). No degradation products could be detected in the extracellular medium by thin-layer chromatography. All peptides tested inhibited the uptake of physiological and of some foreign substrates of the multispecific bile acid transporter (MT). The phalloidin response of liver cells was also inhibited to a similar degree in a concentration-dependent manner. The potency of inhibition did not correlate with the lipophilic properties of the peptides. On the other hand a tight correlation could be documented between the inhibition of cholate transport and that of the phalloidin response. Transport inhibition of typical substrates of the MT by the above renin inhibitors was competitive. In contrast, the transport of a typical substrate of the bilirubin carrier (rifampicin), of amino acids (alpha-aminoisobutyric acid), long chain fatty acids (oleic acid) and cationic compounds (thiamin hydrochloride) was not inhibited by the same renin inhibitors. These results indicate that linear renin inhibiting peptides are taken up into liver cells by carrier proteins related to the MT.

Aminoisobutyric Acids↗
PubMed2005

Measuring rates of reaction in supercooled organic particles with implications for atmospheric aerosol.

The kinetics of heterogeneous reactions involving supercooled organic droplets is reported for the first time. Reactions between ozone and internally-mixed sub-micrometre particles containing an unsaturated alkenoic acid, oleic acid, and an n-alkanoic acid, myristic acid, were studied as a simple model for the oxidation of meat-cooking aerosol. The reactions were followed by monitoring the rate of oleic acid loss using an Aerosol CIMS (chemical ionization mass spectrometry) instrument for real-time particle analysis. Evidence of as much as 32 degrees C supercooling at room temperature was observed depending on particle composition. FTIR spectra of the aerosol also demonstrate features indicative of supercooling. Particles in which crystallization was induced by cooling below room temperature demonstrated decreased reactivity by a factor of 12 compared to supercooled particles of the same composition. This drastic difference in reactivity could have significant implications for the lifetimes of reactive species in ambient aerosol as well as for the accurate source apportionment of particulate matter.

Aerosols↗