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PubMed1995

Effects of duodenal and distal ileal infusions of glucose and oleic acid on meal patterns in rats.

The mechanisms mediating the anorexic effects of nutrients in the proximal and distal small intestine are not clearly understood. We determined the dose-dependent effects of duodenal and distal ileal infusions of glucose and oleic acid on meal patterns in ad libitum feeding rats. Rats with cannulas in both the duodenum and ileum received a 2-h infusion of glucose (0, 800, 1,600, 3,200, 6,400, or 12,800 mumol/h) or oleic acid (0, 48, 240, 640, or 1,280 mumol/h) into the duodenum or ileum at the start of the dark period, and meal patterns were monitored for 4 h. Cumulative food intake was inhibited dose dependently by ileal as well as duodenal infusion of both glucose and oleic acid. Ileal glucose was more inhibitory than duodenal glucose, whereas duodenal oleic acid was more inhibitory than ileal oleic acid. Duodenal glucose and oleic acid inhibited feeding by decreasing meal frequency; ileal oleic acid decreased only meal size, whereas ileal glucose reduced both meal size and frequency. We interpret these results to suggest that ileal oleic acid and glucose suppress feeding by different mechanisms and that these mechanisms differ from those mediating the anorexic responses to oleic acid and glucose in the duodenum.

Animals↗
PubMed1996

Metabolic fate of oleic acid derived from lysosomal degradation of cholesteryl oleate in human fibroblasts.

Low density lipoprotein cholesteryl [14C]oleate (LDL-[14C]CO) was used as a tool to label lysosomes with cholesteryl [14C]oleate (CO) and to follow subsequently the metabolic processing of oleic acid released by acid lipase. Liberated [14C]oleate was incorporated into glycerolipids, mainly into phosphatidylcholine. Incubations in the presence of various concentrations of exogenously added oleic acid and double label experiments showed that oleic acid derived from lysosomal degradation of CO and exogenously added oleic acid distributed in a similar fashion among triacylglycerol and various phospholipids. To further study the metabolism of LDL-derived oleic acid, experiments were performed in which fibroblasts were prelabeled with LDL-[14C]CO. The subsequent processing of lysosome-derived oleic acid was followed with time without LDL-[14C]CO in the medium. From these experiments it became clear that apart from the esterification into glycerolipids a substantial part of lysosome-derived oleic acid was released into the medium. The efflux of oleic acid into the medium preceded the incorporation into glycerolipids, was dependent on the composition of the extracellular medium, and was energy-independent. Our data are compatible with a mechanism in which lysosome-derived fatty acids are transported to the plasma membrane prior to transport to endoplasmic reticulum for esterification. Intra- and extra-cellular factors influence the distribution of lysosome-derived oleic acid among cells and medium.

Cells, Cultured↗
PubMed2001

Interaction between the Gln-Arg 192 variants of the paraoxonase gene and oleic acid intake as a determinant of high-density lipoprotein cholesterol and paraoxonase activity.

Olive oil, rich in oleic acid, could play a particular beneficial role in the anti-atherogenic effects attributed to the Mediterranean diet. Paraoxonase (PON1) has emerged as the component of high-density lipoproteins (HDL) most likely to explain its ability to attenuate the oxidation of low-density lipoproteins. We hypothesised that oleic acid intake might be associated with changes in PON1-HDL associated particles, and investigated the impact, if any, on this association of the PON1-192 polymorphism, a common polymorphism that strongly modulates PON1 activity. Six hundred and fifty-four men randomly selected from the census were studied. Oleic acid intake was calculated from a 72-h recall questionnaire with specific software. Oleic acid intake groups (low vs. high) were created by stratifying the population according the median value as a cut-point. After adjusting for confounding variables, high oleic acid intake was associated with increased HDL cholesterol levels and PON1 activity only in subjects with the QR and the RR genotypes, respectively. Analyses of the variance showed a statistically significant interaction between PON1-192 genotypes and oleic acid intake for log PON1 activity (P=0.005) and a marginally significant interaction for HDL cholesterol (P=0.066). These results suggest that the beneficial effect of increasing oleic acid intake on HDL and PON1 activity at population level is especially observed in subjects carrying the R allele of the PON1-192 polymorphism.

Adult↗
PubMed1989

Is oleic acid the thyroxine binding inhibitor in the serum of ill patients?

The possibility that oleic acid is the thyroxine binding inhibitor in the serum of seriously ill patients was investigated. 3H-Oleic acid was shown to bind directly to human thyroxine-binding globulin (TBG) by the techniques of one and two-dimensional immunoelectrophoresis in combination with autoradiography. However, no correlation was seen between serum thyroxine concentration and oleic acid concentration in two groups of patients, one of which underwent routine cholecystectomy, whilst the other group was admitted to an intensive therapy unit (mortality 75%). No correlation was seen between serum total thyroxine concentration and either stearic, palmitic, linoleic or arachidonic acid concentrations in these groups. Therefore, it was concluded that oleic acid was unlikely to be the circulating inhibitor of thyroxine binding.

Blood Proteins↗
PubMed1996

A stable model of respiratory distress by small injections of oleic acid in pigs.

OBJECTIVE: Development of a stable model of respiratory distress in pigs with oleic acid, fulfilling clinical criteria of the adult respiratory distress syndrome (ARDS). DESIGN: Eight pigs (9.1 +/- 0.7 kg) were anesthetized with pentobarbital, paralyzed with tubocurarine and mechanically ventilated with an FIO2 of 0.6, an I:E ratio of 2:3 and a PEEP of 0.2 kPa. Oleic acid (dissolved 1:1 in 96% alcohol) was administered in a series of multiple injections of 0.1 ml until PaO2 was lower than 8 kPa. MEASUREMENTS AND RESULTS: Careful titration of the oleic acid injections on guidance of the PaO2 established a reproducible respiratory distress (PaO2 = 7.3 +/- 0.8 kPa), in which gas exchange and hemodynamic variables were stable for at least 4 h. The number of oleic acid injections (22 +/- 11, mean and SD) varied between the animals. CONCLUSIONS: With the use of multiple injections of oleic acid, a stable model of early respiratory distress in pigs can be achieved, in spite of individual differences in sensitivity. Such a stable model allows for a diversity of studies on early respiratory distress.

Animals↗
PubMed1976

Effect of bile salts on the absorption of glucose and oleic acid by the cestodes, Hymenolepis diminuta and H. microstoma.

The uptake of 2 mM 14C-glucose by H. diminuta during 1-min incubations was inhibited by addition of 10 mM sodium taurocholate (NaTC) to the incubation media. Preincubation in 10 mM NaTC for 30 min did not increase the inhibition, suggesting that the inhibition was competitive. This was confirmed with a standard Lineweaver-Burk experiment. Addition of 0.35 mM oleic acid to the NaTC micelles did not alter the level of inhibition. Sodium glycocholate (NaGC) did not inhibit the uptake of glucose by H. diminuta. The uptake of glucose by H. microstoma was also inhibited by NaTC, and was not affected by NaGC. H. diminuta absorbed 3.62 mumoles of oleic acid/g dry wt during 15-min incubations in mixed micelles of 10 mM NaTC and 0.35 mM oleic acid. The total uptake was determined as the sum of the ethanol extractable and nonextractable 3H-oleic acid. In 15 mM NaTC, the uptake of oleic acid was reduced by 50%; at 30 mM NaTC the uptake of oleic acid decreased by half again. Substituting NaGC for NaTC, the greatest uptake of oleic acid, 2.63 mumoles/g dry wt, was from mixed micelles of 15 mM NaGC and 0.35 mM oleic acid. Lesser amounts of oleic acid were absorbed from mixed micelles at 5 or 30 mM NaGC. H. microstoma exhibited a similar pattern of oleic acid uptake from mixed micelles with NaTC and NaGC. At all bile salt concentrations tested, H. microstoma absorbed more oleic acid than H. diminuta and incorporated more oleic acid into the nonextractable pool. The possible roles of bile salts in the absorption of oleic acid as indicated by the results herein are discussed.

Animals↗
PubMed2003

Ethanol tolerance in the yeast Saccharomyces cerevisiae is dependent on cellular oleic acid content.

In this investigation, we examined the effects of different unsaturated fatty acid compositions of Saccharomyces cerevisiae on the growth-inhibiting effects of ethanol. The unsaturated fatty acid (UFA) composition of S. cerevisiae is relatively simple, consisting almost exclusively of the mono-UFAs palmitoleic acid (Delta(9)Z-C(16:1)) and oleic acid (Delta(9)Z-C(18:1)), with the former predominating. Both UFAs are formed in S. cerevisiae by the oxygen- and NADH-dependent desaturation of palmitic acid (C(16:0)) and stearic acid (C(18:0)), respectively, catalyzed by a single integral membrane desaturase encoded by the OLE1 gene. We systematically altered the UFA composition of yeast cells in a uniform genetic background (i) by genetic complementation of a desaturase-deficient ole1 knockout strain with cDNA expression constructs encoding insect desaturases with distinct regioselectivities (i.e., Delta(9) and Delta(11)) and substrate chain-length preferences (i.e., C(16:0) and C(18:0)); and, (ii) by supplementation of the same strain with synthetic mono-UFAs. Both experimental approaches demonstrated that oleic acid is the most efficacious UFA in overcoming the toxic effects of ethanol in growing yeast cells. Furthermore, the only other UFA tested that conferred a nominal degree of ethanol tolerance is cis-vaccenic acid (Delta(11)Z-C(18:1)), whereas neither Delta(11)Z-C(16:1) nor palmitoleic acid (Delta(9)Z-C(16:1)) conferred any ethanol tolerance. We also showed that the most ethanol-tolerant transformant, which expresses the insect desaturase TniNPVE, produces twice as much oleic acid as palmitoleic acid in the absence of ethanol and undergoes a fourfold increase in the ratio of oleic acid to palmitoleic acid in response to exposure to 5% ethanol. These findings are consistent with the hypothesis that ethanol tolerance in yeast results from incorporation of oleic acid into lipid membranes, effecting a compensatory decrease in membrane fluidity that counteracts the fluidizing effects of ethanol.

Animals↗
PubMed2002

Effect of oleic acid on Oenococcus oeni strains and Malolactic fermentation in wine.

A different capability to assimilate oleic acid from the culture medium has been demonstrated among malolactic Oenococcus oeni strains. Strains possessing higher percentages of oleic acid and its methylated derivative, dihydrosterculic acid, in their fatty acid profile showed higher cell viability and carried out a complete malolactic fermentation after their transfer into a wine lacking oleic acid. Wine supplementation with Tween 80 (polyoxyethylene-sorbitan-mono-oleate) enhanced cell survival of strains with lower capability to assimilate oleic acid and caused cell growth of strains with higher assimilative capacity, suggesting that oleic acid may act in wine as a survival factor for the former strains and as a growth factor for the latter strains. Practical consequences of these findings are also discussed.

Animals↗
PubMed1992

Inhibition of pulmonary surfactant by oleic acid: mechanisms and characteristics.

The inhibitory effects of oleic acid (OA) on the surface activity of pulmonary surfactant were characterized by use of the oscillating bubble surfactometer, the Wilhelmy balance, and excised rat lungs. Oscillating bubble studies showed that OA prevented lavaged calf surfactant [0.5 mM phospholipid (PL)] from lowering surface tension below 15 mN/m at or above a molar ratio of OA/PL = 0.5. In contrast to inhibition of surfactant by plasma proteins, increasing the surfactant concentration did not eliminate inhibition by oleic acid, which occurred at OA/PL greater than 0.67 on the oscillating bubble even at surfactant concentrations of 1.5 and 12 mM PL. Studies of surfactant adsorption showed that preformed films of OA had little effect on the adsorption of pulmonary surfactant. Wilhelmy balance studies showed that OA did interfere with the ability of spread films of surfactant to reach low surface tensions during dynamic compression. Further balance experiments with binary films of OA and dipalmitoyl phosphatidylcholine showed that these compounds were miscible in surface films. Together these findings suggested that OA inhibited pulmonary surfactant activity by disrupting the rigid interfacial film responsible for the generation of very low surface tension during dynamic compression. Mechanical studies in excised rat lungs showed that instillation of OA gave altered deflation pressure-volume characteristics with decreased quasi-static compliance, indicating disruption of pulmonary surfactant function in situ. This alteration of mechanics occurred without major changes in the composition of lavaged PLs or in the tissue compliance of the lungs defined by mechanical measurements during inflation-deflation with saline.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Ca-mediated and independent effects of arachidonic acid on gap junctions and Ca-independent effects of oleic acid and halothane.

In Novikoff hepatoma cell pairs studied by double perforated patch clamp (DPPC), brief (20 s) exposure to 20 microM arachidonic acid (AA) induced a rapid and reversible uncoupling. In pairs studied by double whole-cell clamp (DWCC), uncoupling was completely prevented by effective buffering of Cai2+ with BAPTA. Similarly, AA (20 s) had no effect on coupling in cells perfused with solutions containing no added Ca2+ (SES-no-Ca) and studied by DPPC, suggesting that Ca2+ influx plays an important role. Parallel experiments monitoring [Ca2+]i with fura-2 showed that [Ca2+]i increases with AA to 0.7-1.5 microM in normal [Ca2+]o, and to approximately 400 nM in SES-no-Ca solutions. The rate of [Ca2+]i increase matched that of Gj decrease, but [Ca2+]i recovery was faster. In cells studied by DWCC with 2 mM BAPTA in the pipette solution and superfused with SES-no-Ca, long exposure (1 min) to 20 microM AA caused a slow and virtually irreversible uncoupling. This result suggests that AA has a dual mechanism of uncoupling: one dominant, fast, reversible, and Ca(2+)-dependent, the other slow, poorly reversible, and Ca(2+)-independent. In contrast, uncoupling by oleic acid (OA) or halothane was insensitive to internal buffering with BAPTA, suggesting a Ca(2+)-independent mechanism only.

Animals↗
PubMed1990

Oleic acid: its effects on stratum corneum in relation to (trans)dermal drug delivery.

Calorimetric studies with porcine stratum corneum (SC) have shown that the lipid phase transitions associated with the intercellular bilayers are markedly affected by treatment with oleic acid. Specifically, the transition temperatures (Tm) and cooperativity are reduced, whereas no effect was observed on the endotherm associated with keratin denaturation, suggesting that oleic acid primarily affects the SC lipids. The decrease in the lipid-associated Tm's was further correlated with the amount of oleic acid taken up by the SC. Parallel experiments with silastic implied that the uptake is dependent on the thermodynamic activity of oleic acid in the vehicle itself. The in vitro transport of Piroxicam across human and hairless mouse skin (HMS) was significantly enhanced by oleic acid, as a function of the extent of oleic acid uptake, with an attendant change in Tm. These results emphasize the role of SC lipids in percutaneous absorption. Transport also depended on the donor concentration of ionized drug suggesting that the enhanced transport mechanism cannot be accounted for solely on the principles of the classical pH-partition hypothesis. Accordingly, a model of skin permeability enhancement involving solid-fluid phase separation within the SC lipids is proposed for oleic acid, consistent with the existing phospholipid literature. In conjunction with the use of oleic acid as an enhancer, very soluble hydrophilic salts were recognized as key factors in attaining maximum delivery. Oleic acid uptake, lipid delta Tm, and enhanced drug flux were all found to correlate, exhibiting a bell-shaped curve as a function of the ethanol vehicle concentration. Therefore, uptake and/or DSC experiments are useful for formulating enhanced topical delivery systems.

Administration, Cutaneous↗
PubMedDate not supplied

Computational approach to solvent-free synthesis of ethyl oleate using Candida rugosa and Candida antarctica B Lipases. I. Interfacial activation and substrate (ethanol, oleic acid) adsorption.

This paper presents the results of a MM2 study of the adsorption of oleic acid and ethanol/water in the tunnel and active-site models of lipases from Candida rugosa and Candida antarctica B. The role of an interface polar/no polar in the opening of C. rugosa lipase's lid is also addressed, discussed and analyzed at the level of the conformational changes needed to achieve the lipase open form. The adsorption of oleic acid and alcohols considering C. antarctica B, a lipase not interfacially activated, is also presented. In this case, the tunnel is shorter than in case of C. rugosa lipase. Two different pockets can be visualized at the active site-tunnel model of C. antarctica B lipase: one for the acyl group and another for the alcohol. Wrong location of alcohol and oleic acid severely hinders reaction because it hinders the H-transfer to histidine, a key step in the reaction mechanism. Right location of alcohol decreases the possibility of alcohol inhibition. In the case of C. rugosa, no restrictions for ethanol/water location are found. For that lipase, a second adsorption site for oleic acid (outside the tunnel) is presented. This site is the exit tunnel of the ester product when oleic acid is adsorbed in the tunnel. Experimental results of our own that correlate with this study are presented.

Adsorption↗
PubMed1967

Cell permeability: a factor in the biotin-oleate relationship in Lactobacillus arabinosus. II. Effect of oleic acid and other surfactants on free biotin uptake.

Bound biotin-saturated cells were incubated in the presence of biotin and glucose (37 C, pH 7.5) with or without oleic acid, Tween 20, 40, 60, and 80, Aerosol OT, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide, Triton X-100, Non-Ion-Ox, and Haemo-Sol. With low concentrations (up to 5 mug/ml) and short reaction times (up to 10 min), oleic acid stimulated free biotin accumulation. Increased concentrations (10 to 50 mug/ml) or reaction times (10 to 30 min) caused progressive reductions in uptake or increased release of previously accumulated vitamin. Combination of Tween 40 (1 mg/ml) with oleic acid (up to 50 mug/ml) detoxified oleic acid and stimulated free biotin uptake. Oleic acid (5 mug/ml or more) reduced cell viability, an effect which was overcome by Tween 40. All other surfactants tested stimulated free biotin accumulation at sublethal concentrations. Aerosol OT and SDS exhibited the same degree of stimulatory activity as detoxified oleic acid; however, at concentrations higher than 200 mum, a rapid decrease in vitamin accumulation was observed which paralleled that caused by increased oleic acid concentrations. The results suggest that oleic acid and other surfactants affect the permeability of cells of Lactobacillus plantarum (formerly called L. arabinosus) in a similar manner.

Aerosols↗
PubMed1989

Effect of calcium and magnesium ions on the intestinal absorption of oleic acid in vitro.

The effect of Ca++ and Mg++ upon intestinal absorption of oleic acid was investigated using two in vitro models: rat isolated jejunal loops at 30 degrees C and 37 degrees C and mouse jejunal explants at 37 degrees C. At 30 degrees C or at 37 degrees C, Ca++ significantly increased 14C oleic acid uptake by rat isolated jejunal loops or mouse jejunal explants; at 37 degrees C, Ca++ significantly enhanced lipid exocytosis in rat intestinal loops but not in mouse jejunal explants; in both models, in the presence of Ca++ and at 37 degrees C, Mg++ significantly improved the esterification of oleic acid phospholipids and triacylglycerols, as shown by the increase in triacyglycerol synthesis in rat isolated intestinal loops or by the increase in triacylglycerols recovered from the incubation media of mouse jejunal explants; experiments carried out with rat isolated jejunal loops highlighted the determinant role of temperature in oleic acid absorption processes. The present work shows that the simultaneous presence of Ca++ and Mg++ did not impede oleic acid absorption processes but, on the contrary, enhanced them.

Animals↗