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PubMedDate not supplied

[The influence of oleic acid on the aminopeptidase activity in astrocytes of the rat].

INTRODUCTION: Changes in fatty acid composition of membrane lipids induce modifications on the activity of several enzymes and membrane transporters. Glial cells possess aminopeptidases which are located in the plasma membranes. Aminopeptidases are generally zinc-metalloenzymes which hydrolyze peptide bonds near the N-terminal end of peptides and polypeptides. The importance of these enzymes is based on their major role in protein metabolism and in the regulation of circulating hormones and biologically active peptides. OBJECTIVE: We study the effects of oleic acid on several aminopeptidase activities in primary cultures of rat astroglia, using aminoacyl-beta-naphthylamides as substrates. RESULTS: Oleic acid inhibits Ala-, Cys-, Leu- and Tyr-aminopeptidase activities, but not modifies Arg- and pGlu-aminopeptidase activities. CONCLUSIONS: Oleic acid modulates aminopeptidase activities in astrocytes. This could be related with intercellular communication and molecular transport processes, in which the astrocyte function has been involved. Furthermore, oleic acid might modulate the action of opioid peptides and steroid hormones on astroglial cells.

Aminopeptidases↗
PubMed1971

The uptake of oleic acid by rat small intestine: a comparison of methodologies.

The interaction between long-chain and medium-chain lipids during intestinal absorption was examined using several model systems. A decrease in steady-state triolein (LCT) output in thoracic duct lymph after addition of trioctanoin (MCT) to the duodenal infusion confirmed previous studies in unanesthetized rats which demonstrated inhibition of steady-state LCT uptake from the small intestinal lumen by MCT. In slices of everted rat jejunum octanoic acid reduced incorporation into triglyceride and initial uptake of (14)C-labeled oleic acid from micellar solutions. Inhibition of uptake did not occur at 0 degrees C, when triglyceride synthesis was blocked. Incubation of slices at low pH (5.8) or in the presence of dimethyl sulfoxide also reduced uptake of oleic acid and its incorporation into triglyceride. However, when everted sacs of jejunum were similarly incubated, octanoate, dimethyl sulfoxide, or low pH caused no inhibition of oleic acid uptake or esterification. The results indicate that the significance of kinetic data describing intestinal fatty acid absorption which were obtained from experiments conducted in vitro is highly questionable, and that suitable models for in vivo uptake kinetics have yet to be developed. However, analysis of the in vitro kinetic data suggests that the intestinal mucosal membrane does not function as a simple lipid interface with respect to fatty acid absorption.

Animals↗
PubMed2002

Vasculoprotective effects of oleic acid: epidemiological background and direct vascular antiatherogenic properties.

BACKGROUND AND AIMS: The use of the "Mediterranean diet" as a means of preventing atherosclerotic vascular disease is gaining increasing acceptance. As early as in the late 1950s, it was found that the inhabitants of Greece and Southern Italy had a very low incidence of coronary artery disease and that, among other components, their diets were very rich in oleic acid, the main constituent of the olive oil, making up about 29% of their daily caloric intake. It is now clear that, in addition to its relatively minor effects on cholesterol levels, oleic acid directly interferes with the inflammatory response characterising early atherogenesis due to the endothelial expression of adhesion molecules for circulating monocytes. RESULTS: In in vitro models of early atherogenesis based on cytokine-stimulated cultured endothelial cells, we have observed that the incorporation of oleic acid in total cell lipids is accompanied by decreased expression of a number of major pro-inflammatory proteins, such as endothelial leukocyte adhesion molecules. CONCLUSIONS: The results of our investigations indicate that oleic acid has a direct vascular atheroprotective effect, and suggest that it may be possible to prevent atherosclerosis by modulating the vascular response to classical triggers (high levels of cholesterol and the advanced glycation end-products of diabetes) using a strategy that is fundamentally different from, and therefore complementary to, drug-based therapy.

Arteriosclerosis↗
PubMed1977

Influence of contraceptive steroids on the turnover of plasma free arachidonic and oleic acids.

The turnover of plasma free oleic and arachidonic acids was determined in five healthy women before and after 3 months contraceptive treatment with a daily dose of 0.05 mg ethinyl estradiol and 0.25 mg d-norgestrel administered in a cyclic manner. The contraceptive steroids did not significantly influence the total plasma free fatty acid (FFA) concentration or the turnover of oleic acid. However, during hormone administration the fractional turnover of arachidonic acid increased by 40 per cent and its arterial concentration fell by 20 per cent. The portion of saturated fatty acids in the FFA fraction decreased during the contraceptive treatment. It is concluded that the treatment with contraceptive steroids (1) had no effect on the turnover of the main part of the FFA fraction, (2) increased the transport of the polyunsaturated arachidonic acid through the plasma pool, possibly as an effect of the estrogen component, and (3) stimulated the desaturation of saturated fatty acids to monoenes.

Adult↗
PubMed1995

A sensitive method to analyze in vitro secretion of lipoproteins: distribution of apolipoproteins is modulated by oleic acid in HepG2 cells.

Lipoprotein metabolism can be studied by the analysis of lipoprotein production in cell culture. An inherent problem in such an analysis is the low concentration of lipoproteins in culture supernatants. The difficulty comes from the fact that the samples must be concentrated prior to any analysis. The concentrating methods (e.g., dialysis or ultrafiltration) induce a heterogeneous loss of components. In order to minimize these losses, we have developed a sensitive three-step method to analyze the distribution and the amount of apolipoproteins in the different classes of lipoproteins secreted by the human hepatoma cell line HepG2. Cells were labeled with [14C]acetate and [35S]methionine for 4 h in the presence of 0.08 mM BSA, complexed or not, with 0.75 mM oleic acid. The 14C-radiolabeled cellular lipids were extracted and analyzed by thin-layer chromatography and the secreted lipoproteins were analyzed by the following three-step method. First, the lipoproteins were isolated by flotation ultracentrifugation. Second, total lipoproteins were directly applied to native agarose-acrylamide gel electrophoresis in order to separate lipoproteins with respect to their diameter. After migration, the gel was sliced and each fragment was eluted in a buffer containing sodium dodecyl sulfate and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. This allowed evaluation of the proportion of apolipoproteins in lipoproteins. Oleic acid (0.75 mM) increased the rate of triglyceride biosynthesis and apoB-100 secretion by 1.7-fold and 2.4-fold, respectively. Moreover, oleic acid treatment modified the profile of secreted lipoproteins. Oleic acid-treated cells secreted more apoB-100 within VLDL than control cells.

Apolipoproteins↗
PubMed1975

Turnover of plasma oleic acid measured by radio-gas chromatography.

Gas-liquid chromatography with radioactivity detection (Radio-GLC) was investigated as an analytical means of determining the fractional turnover rates of plasma free fatty acids. For this purpose normal dogs were infused with 1.838 muCi/min of [1-14C]oleic acid complexed with albumin and plasma samples were taken at 0 to 110 minutes. The plasma free fatty acids were isolated by a modified Dole extraction and the methyl esters, prepared by diazomethylation, were identified and quantitated by GLC and radio-GLC using radioactive methyl heptadecanoate as internal standard. The study demonstrates that physiologically feasible infusion rates and loads of radioactive acids can be found which permit accurate analyses of plasma free fatty acids by radio-GLC. During a 2-hour infusion no labeled acid other than oleic appeared in plasma indicating that the method could be used to study the turnover of a mixture of fatty acids simultaneously. These results also indicate that conventional methods of determination of radioactivity in purified extracts can be employed without concern for recycling of label among the fatty acids, at least over short periods of time. The radio-GLC technique described yields approximately 20% higher fractional turnover times for oleic acid than do standard methods.

Animals↗
PubMed2004

Comparative toxicity of oleic acid and linoleic acid on Jurkat cells.

BACKGROUND: Lipid emulsions for parenteral nutrition commercially available are mainly composed of long-chain triacylglycerol containing a high proportion of alpha-6 polyunsaturated fatty acids or alpha-9 monounsaturated fatty acids. The immunological impact of such therapy is particularly important because parenteral and enteral diets are often administered to critical ill patients. The comparative toxicity of oleic acid and linoleic acid on Jurkat cells, a human T lymphocyte cell line, and the type of cell death induced by these fatty acids were determined. METHODS: Cell death was investigated by cytometry: decrease in cell volume, increase of granularity, DNA fragmentation, phosphatidylserine externalization, mitochondrial depolarization, lipid accumulation; by fluorescence microscopy: chromatin condensation and acridine orange/ethidium bromide assay; and by RT-PCR: mRNA expression of apoptotic genes. RESULTS: Evidence is presented herein that oleic acid is much less toxic to Jurkat cells than linoleic acid. Both fatty acids promote apoptosis and necrosis of these cells. The mechanism of cell death induced by these fatty acids seem to involve with mitochondrial depolarization, lipid accumulation and the levels of C-MYC and P53 mRNA expression. CONCLUSION: Therefore, oleic acid may offer an immunological less harmful alternative to linoleic acid for parenteral and enteral diets preparation.

Apoptosis↗
PubMed1982

Pulmonary epithelial permeability is immediately increased after embolisation with oleic acid but not with neutral fat.

Pulmonary fat embolism occurs frequently after trauma but its functional significance is often unclear. To obtain direct evidence of lung damage caused by fat embolism we have measured changes in permeability of the alveolar-capillary interface. A permeability index was derived from the half time clearance from lung to blood (T1/2LB) of 99mTcDTPA introduced into the lung in a 1 ml bolus. Three groups of rabbits were studied. Baseline T1/2LB. did not differ significantly between groups. After intravenous injection of saline placebo in one group and of 300 mg/kg triolein in another group there was no change in permeability index. After intravenous injection of 100 mg/kg oleic acid in the third group there was an immediate change in T1/2LB from a monoexponential baseline 280 +/- 20 min (SEM) to a multiexponential curve which was resolved into two components, one with a T1/2LB of 3.2 +/- 0.6 min (SEM) and the other 39.5 +/- 7.6 min (SEM). Statistically significant changes in alveolar-arterial PO2 difference, dynamic compliance, chest radiography, and postmortem lung water accompanied the changes in T1/2LB in this group. There were no significant changes in these variables in the placebo or triolein group. Histological studies of the lung tissue of these animals using the osmic acid stain for fat showed no fat in the placebo group, extensive fat embolisation which was densely stained in the triolein group and much less densely stained fat in the oleic acid group. Measurement of the permeability of the alveolar-capillary interface provides direct evidence of lung damage after oleic acid embolisation. There were no functional changes in animals with extensive embolisation with triolein.

Animals↗
PubMed1984

Effect of intraluminal pH on cholesterol and oleic acid absorption from micellar solutions in the rat.

We have studied the effects of intraluminal pH on micellar solubilization and on absorption rate of oleic acid (OA) and cholesterol in proximal small bowel segments and the total small bowel in rats. In addition, pH effect on fecal excretion of [3H]cholesterol was studied over a period of 4 days after duodenal administration of cholesterol in solutions at different pH using beta-sitosterol as a nonabsorbable marker. Rates of absorption of OA and cholesterol were, respectively, 1.8 and 1.9 times higher at pH 5.5 in both proximal bowel segments as compared with pH 6.5 (P less than 0.001). Similar observations were made when the whole small bowel was perfused. At pH 5.5, 1.8 times more OA was absorbed and 1.5 times more cholesterol than at pH 6.5 (P less than 0.001). Also, fecal output of radioisotope following administration of pH 5.5 solution was only 47% of the excretion using the pH 6.5 solution. Excretion of beta-sitosterol, which serves as a nonabsorbable marker, was not affected by pH differences. In vitro measurements of micellar solubility at the two pH levels by ultracentrifugation showed that an increase of one pH unit resulted in a decreased number of particles in the oil phase (oleic acid and cholesterol in the emulsified particles in pH 6.5 solution is 37 and 34%, respectively, of that in the pH 5.5 solution) due to increased solubilization into the micellar phase. Measurements of monomer activities of OA and cholesterol using a polyethylene disk technique showed a significantly higher activity at the lower pH.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Cellular Fatty Acid profiles of lactobacillus and lactococcus strains in relation to the oleic Acid content of the cultivation medium.

Cellular fatty acids of 10 strains of lactic acid bacteria were analyzed. The purpose of this work was to find lactic acid bacteria with high lactobacillic acid contents. The bacteria studied were unable to synthesize oleic acid. Some strains did not synthesize lactobacillic acid, although all were able to form dihydrosterculic acid. Twenty-one to thirty-four percent of the fatty acid content of Lactobacillus fermentum and L. buchneri was lactobacillic acid, and these species were chosen for future studies of environmental factors affecting cyclopropane fatty acid synthesis.

Journal Article↗
PubMed1988

Effects of oleic acid on the biosynthesis of lipoprotein apoproteins and distribution into the very-low-density lipoprotein by the isolated perfused rat liver.

The effects of oleic acid on the biosynthesis and secretion of VLDL (very-low-density-lipoprotein) apoproteins and lipids were investigated in isolated perfused rat liver. Protein synthesis was measured by the incorporation of L-[4,5-3H]leucine into the VLDL apoproteins (d less than 1.006) and into apolipoproteins of the whole perfusate (d less than 1.21). Oleate did not affect incorporation of [3H]leucine into total-perfusate or hepatic protein. The infusion of oleate, however, increased the mass and radioactivity of the VLDL apoprotein in proportion to the concentration of oleate infused. Uptake of oleate was similar with livers from fed or fasted animals. Fasting itself (24 h) decreased the net secretion and incorporation of [3H]leucine into total VLDL apoprotein and decreased the output of VLDL protein by the liver. A linear relationship existed between the output of VLDL triacylglycerol (mumol/h per g of liver) and secretion and/or synthesis of VLDL protein. Net output of VLDL cholesterol and phospholipid also increased linearly with VLDL-triacylglycerol output. Oleate stimulated incorporation of [3H]leucine into VLDL apo (apolipoprotein) E and apo C by livers from fed animals, and into VLDL apo Bh, B1, E and C by livers from fasted rats. The incorporation of [3H]leucine into individual apolipoproteins of the total perfusate lipoprotein (d less than 1.210 ultracentrifugal fraction) was not changed significantly by oleate during perfusion of livers from fed rats, suggesting that the synthesis de novo of each apolipoprotein was not stimulated by oleate. This is in contrast with that observed with livers from fasted rats, in which the synthesis of the total-perfusate lipoprotein (d less than 1.210 fraction) apo B, E and C was apparently stimulated by oleate. The observations with livers from fed rats suggest redistribution of radioactive apolipoproteins to the VLDL during or after the process of secretion, rather than an increase of apoprotein synthesis de novo. It appears, however, that the biosynthesis of apo B1, Bh, E and C was stimulated by oleic acid in livers from fasted rats. Since the incorporations of [3H]leucine into the VLDL and total-perfusate apolipoproteins were increased in fasted-rat liver when the fatty acid was infused, part of the apparent stimulated synthesis of the VLDL apoprotein may be in response to the increased formation and secretion of VLDL lipid.

Animals↗
PubMed1987

13-week subchronic toxicity study with morpholine oleic acid salt administered to B6C3F1 mice.

The effect of subchronic administration of morpholine oleic acid salt (MOAS) was studied in B6C3F1 mice. The dose levels of MOAS used were 0%, 0.15%, 0.3%, 0.6%, 1.25%, and 2.5% in drinking water. Reduced weight gains were noted in both sexes in the 2.5% group as compared to controls, but reductions were not significant. Water consumption values showed a dose-related tendency for a decrease in both females and males. Urine analysis showed significant elevation of specific gravity in the males in the 0.6%, 1.25%, and 2.5% groups and the females in the 1.25% and 2.5% groups. Significant elevation of plasma urea nitrogen was observed in males of the 1.25% and 2.5% groups and in females of the 0.6%, 1.25%, and 2.5% groups. The relative weight of the kidneys showed a dose-dependent increase that was statistically significant for the 1.25% and 2.5% MOAS groups in both sexes. Except for cloudy swelling of the proximal tubules of the kidneys in mice on the 2.5% regimen, no treatment-related histopathological alterations were observed in organs of either sex.

Animals↗
PubMed1990

The effects of graded administration of positive end expiratory pressure on the fluid filtration rate in isolated rabbit lungs, using normal lungs, hydrostatic oedema lungs and oleic acid induced oedema.

The influence of positive end expiratory pressure (PEEP) on the fluid filtration rate (FFR) in the pulmonary circulation has been the subject of considerable investigation but data are conflicting. We studied twenty-nine isolated rabbit lung preparations, FFR was sensed by a force transducer. Autologous blood was used to prime the perfusion circuit. Hydrostatic oedema was achieved by increasing the left atrial pressure to 16 mmHg. In order to bring about increased membrane permeability oleic acid was injected through the pulmonary artery. Increasing and decreasing levels of PEEP at 0, 5, 10 and 15 cm H2O were each used for ten minutes in each of three experimental models. The FFR, pH, mean pulmonary arterial pressure (MPAP), mean left atrial pressure (MLAP), PaO2, PaCO2 and oncotic pressure were measured in each experiment. There was a significant correlation between PEEP and FFR (+0.94) in non-oedema lungs. With no PEEP the FFR was 0 g/min and with 15 cm of PEEP it increased to 0.07 g/min, on removing the PEEP the FFR returned to 0 g/min. In the hydrostatic lung oedema model the correlation was also significant but negative (r = -0.94). With no PEEP the FFR was 0.33 g/min, with PEEP of 15 cm H2O it decreased to 0.08 g/min. No correlation between PEEP and FFR was found in the oleic acid preparation. In the normal lung PEEP increases capillary hydrostatic pressure and total lung vascular area and decreases interstitial pressure. It is by these mechanisms that PEEP causes an increase in FFR. In the hydrostatic oedema model PEEP decreases FFR by increasing the interstitial pressure and by decreasing the total lung vascular area. In the oleic acid preparation the coefficient of filtration is so large that small changes in pressure or vascular area do not modify the FFR. We suggest that PEEP may be beneficial by decreasing FFR in hydrostatic lung oedema, but it may increase the FFR in the normal lung, while having no effect in oleic acid lung injury.

Airway Resistance↗
PubMed2006

Cyclic fatty acid monomer formation in domestic frying of frozen foods in sunflower oil and high oleic acid sunflower oil without oil replenishment.

During the frying process, oxidation, hydrolysis, polymerization, isomerization, and cyclization occur. Polymers and Cyclic fatty acid monomers (CFAM) are potentially toxic, and the latter are detected at relatively low levels (0.01-0.7%) in used frying oils. Twenty fryings of different frozen foods were carried out over 10 consecutive days in sunflower oil (SO) and in high oleic acid sunflower oil (HOSO). Fatty acid methyl ester derivates were hydrogenated with platinum oxide catalyst under hydrogen. Ethyl palmitate was added as an internal standard before hydrogenation. The CFAM obtained were isolated, concentrated and quantified by HPLC using a reverse-phase column followed by gas chromatography. Linear adjustments between total and individual CFAM content and the number of frying operations performed with both oils were established by analysis of variance. The comparison between linear equation adjustments of both oils was performed by a two-way analysis of covariance. After 20 fryings 15.4 +/- 0.06 g polar content/100 g oil, 7.15 +/- 0.08 g polymers/ oil, 11.52 +/- 0.08 g polymers/100g oil and 855 +/- 8.9 mg CFAM/kg oil were detected in SO. A 10 mg/100 mg oil of altered fatty acid content correspond to 700 mg/kg CFAM, while 25% polar material and 10% polymer content would correspond to about 850-1,000 mg CFAM/kg oil. Data suggest that frying with SO produces in each new frying 9 mg CFAM/kg more than frying with HOSO (p < 0.001). After frying cyclopentyl structures were more than twice as abundant as cyclohexyl fatty acids in both oils. Bicyclic compound formation was significantly higher in SO (p < 0.001). Because digestion and absorption of polar material, polymers and CFAM occur, data clearly show the advantageousness and advisability of frying with HOSO rather than SO.

Cooking↗
PubMed1996

l-Menthol, oleic acid and lauricidin in absorption enhancement of free and sodium salt of diclofenac using ethanol treated silicone membrane as model for skin.

The mechanism of l-menthol, oleic acid and lauricidin as enhancers on percutaneous absorption was examined using diclofenac (DH) as a hydrophobic drug and sodium diclofenac (DNa) as a hydrophilic drug in in vitro diffusion experiments with two kinds of membranes: ethanol-treated and untreated silicone membranes; these were models for the lipid and pore pathways of skin. A 20% w/w ethanol-aqueous solution decreased the flux of DH but increased the flux of DNa significantly across the treated membrane compared with those fluxes across the untreated membrane, suggesting that DH penetrated by the lipid pathway and DNa by the pore pathway. The permeability of DNa through the pore pathway decreased significantly across the treated membrane with the addition of oleic acid and lauricidin. l-Menthol increased the permeability coefficients of DH and DNa more in a treated membrane than in an untreated one, showing the same tendency as in rat skin. Thus, while oleic acid and lauricidin did not increase the permeation of DNa by the pore pathway, l-menthol appeared to enhance the permeation of the drug by both the lipid and pore pathways.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Stearoyl-ACP and oleoyl-PC desaturase genes cosegregate with quantitative trait loci underlying high stearic and high oleic acid mutant phenotypes in sunflower.

The genetic control of the synthesis of stearic acid (C18:0) and oleic acid (C18:1) in the seed oil of sunflower was studied through candidate-gene and QTL analysis. Two F(2) mapping populations were developed using the high C18:0 mutant CAS-3 crossed to either HA-89 (standard, high linoleic fatty acid profile), or HAOL-9 (high C18:1 version of HA-89). A stearoyl-ACP desaturase locus (SAD17A), and an oleoyl-PC de-saturase locus (OLD7) were found to cosegregate with the previously described Es1 and Ol genes controlling the high C18:0 and the high C18:1 traits, respectively. Using linkage maps constructed from AFLP and RFLP markers, these loci mapped to LG1 (SAD17A) and to LG14 (OLD7) and were found to underlie the major QTLs affecting the concentrations of C18:0 and C18:1, explaining around 80% and 56% of the phenotypic variance of these fatty acids, respectively. These QTLs pleiotropically affected the levels of other primary fatty acids in the seed storage lipids. A minor QTL affecting both C18:0 and C18:1 levels was identified on LG8 in the HAOL-9xCAS-3 F(2). This QTL showed a significant epistatic interaction for C18:1 with the QTL at the OLD7 locus, and was hypothesized to be a modifier of Ol. Two additional minor C18:0 QTLs were also detected on LG7 and LG3 in the HA-89xCAS-3 and the HAOL-9xCAS-3 F(2) populations, respectively. No association between a mapped FatB thioesterase locus and fatty acid concentration was found. These results provide strong support about the role of fatty acid desaturase genes in determining fatty acid composition in the seed oil of sunflower.

Journal Article↗