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At least 271 records · Page 15Linked to original sources
PubMed2000

Combined effect of oleic acid and polyethylene glycol 200 on buccal permeation of [D-ala2, D-leu5]enkephalin from a cubic phase of glyceryl monooleate.

The combined use of the lipophilic permeation enhancer, oleic acid together with polyethylene glycol 200 (PEG 200) as a co-enhancer and incorporated into the cubic liquid crystalline phase of glyceryl monooleate was investigated in the ex vivo buccal permeation of [D-Ala2, D-Leu5]enkephalin (DADLE) through porcine buccal mucosa mounted in a Franz cell. The addition of oleic acid (1%) and PEG 200 (1-10%) did not change the intact appearance of the cubic phase. PEG 200 increased the aqueous solubility of oleic acid incorporated into the cubic phase and hence promoted the transport of oleic acid into the porcine buccal mucosa. The solubilising effect of PEG 200 on oleic acid incorporated into the cubic phase was dependent on the PEG 200 concentration but was non-linear. The buccal permeation flux of DADLE significantly increased when 5% (P<0.01) or 10% (P<0.001) of PEG 200 was co-administered with 1% oleic acid compared with the cubic phase containing 1% oleic acid alone. The present results suggest that PEG 200 enhances the action of the lipophilic permeation enhancer oleic acid and that the combination of oleic acid and PEG 200 as a co-enhancer can be a useful tool to improve the membrane permeability in the buccal delivery of peptide drugs using a cubic liquid crystalline phase of glyceryl monooleate and water.

Animals↗
PubMed2006

Structural analysis of oligomeric molecules formed from the reaction products of oleic acid ozonolysis.

The products arising from the ozonolysis of oleic acid (cis-9-octadecenoic acid) in solution have been studied using negative ion mode electrospray ionization ion trap mass spectrometry. Oleic acid is an important component of atmospheric organic aerosol and is a key model species in predicting aerosol physical and chemical characteristics. The four predicted reaction products, 1-nonanal, nonanoic acid, 9-oxononanoic acid, and azelaic acid, were all observed in roughly equal yields. In addition to these products a large number of higher molecular weight compounds were detected with m/z ratios of up to 1000 Daltons. Tandem mass spectrometry of these larger ions revealed thatthey represented a complex mixture of linear alpha-acyloxyalkyl hydroperoxides, secondary ozonides, and cyclic diperoxides, formed by reactions between ozonolysis products and Criegee intermediates. These comprise the first directly elucidated structures of large oligomeric species from oleic acid ozonolysis. The degree of oligomerization and hence molecular weight distribution was observed to increase with reaction time in solution.

Aldehydes↗
PubMed1988

The influence of oleic acid on cAMP accumulation of thyroid plasma membrane activated by thyrotropin.

Several thyroid hormone binding inhibitors have been described in nonthyroid illness. One of the major inhibitors, oleic acid, is present in excess amounts in sera of patients with nonthyroid illness. In this study, we demonstrated that oleic acid inhibited the cAMP accumulation of thyroid plasma membrane activated by thyrotropin at 50 mumol/l and higher concentrations. In the presence of albumin, oleic acid significantly inhibited the cAMP accumulation of plasma membrane activated by thyrotropin at 2.4 mmol/l (P less than 0.01 when the albumin concentration was 40 g/l and pH was 7.4; P less than 0.001 when the albumin concentration was 20 g/l and pH was 7.2). These findings suggest that in nonthyroid illness, especially at a low albumin concentration and low blood pH, a high oleic acid concentration may influence the thyroid function directly in addition to inhibiting the thyroid hormone binding to serum protein. Oleic acid also could inhibit 5'-guanylylimidodiphosphate- and forskolin-induced cAMP production in thyroid plasma membranes. Therefore, the inhibiting effect of oleic acid may be through the action of oleic acid on the catalytic unit of the hormone-sensitive adenylate cyclase system.

Cell Membrane↗
PubMed1990

Oleic acid stimulation of apolipoprotein B secretion from HepG2 and Caco-2 cells occurs post-transcriptionally.

HepG2 and Caco-2 cells were studied to compare the regulation of liver and intestinal apolipoprotein (apo) biosynthesis and secretion by fatty acids. Incubation with fatty acid consistently stimulated apoB production by both HepG2 and Caco-2 cells. Media concentrations of apoB, determined by radioimmunoassay, were approx. 3-fold greater for cells incubated for 24 h in serum-free medium containing oleic acid bound to albumin than for cells incubated with albumin alone. Oleic acid also resulted in a 2-3-fold accumulation of cellular triacylglycerol for HepG2 cells and Caco-2 cells. Cellular apoB and media and cellular apoA-I concentrations were not affected by oleic acid. Immunoblotting with a monoclonal antibody against human apoB confirmed a greater mass of apoB in media from HepG2 and Caco-2 cells incubated with oleic acid. Radiolabeled apoB-100 was also increased in media from HepG2 and Caco-2 cells incubated with [35S]methionine for 24 h in the presence of oleic acid, suggesting enhanced apoB synthesis. However, apoB mRNA concentrations were unchanged in response to oleic acid. Gel filtration of media by fast protein liquid chromatography (FPLC) revealed a redistribution of apoB from LDL-sized particles to VLDL or chylomicrons in media from Caco-2 cells incubated with oleic acid, whereas apoB remained in LDL for HepG2 cells. ApoA-I in media from HepG2 and Caco-2 cells eluted as free or lipid-poor apoA-I, and the apoA-I distribution was unaltered by incubation with oleic acid. These data demonstrate that HepG2 and Caco-2 cells maintained in supplemented serum-free medium respond to oleic acid by a similar post-transcriptional increase in apoB synthesis, but different packaging of apoB into triacylglycerol-rich lipoproteins.

Apolipoproteins B↗
PubMed2003

Oleic acid induces GAP-43 expression through a protein kinase C-mediated mechanism that is independent of NGF but synergistic with NT-3 and NT-4/5.

We have recently shown that the presence of albumin in astrocytes triggers the synthesis and release of oleic acid, which behaves as a neurotrophic factor for neurons. Thus, oleic acid promotes axonal growth, neuronal clustering, and the expression of the axonal growth-associated protein, GAP-43. In this work we show that oleic acid upregulates GAP-43 expression by a protein kinase C (PKC)-dependent mechanism. Since GAP-43 expression has been shown to be upregulated by several neurotrophins, we investigated the relationship between the effect of oleic acid and that of NGF, neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5) on GAP-43 expression. Our results indicate that NGF is not involved in the neurotrophic effect of oleic acid because the addition of NGF did not modify the effect of oleic acid on GAP-43 expression. Neither NT-3 nor NT-4/5 alone modified GAP-43 expression. However, NT-3 and NT-4/5 acted synergistically with oleic acid to increase GAP-43 expression. The lack of effect of NGF as compared to other neurotrophins is not unexpected since we have not found TrkA expression under our experimental conditions. The effect of oleic acid on GAP-43 expression must be independent of autocrine factors synthesized by neurons because this effect was also observed at low cellular densities. In conclusion, our results indicate that oleic acid behaves as a neurotrophic factor, inducing GAP-43 expression through a PKC-mediated mechanism that is not mediated by other neurotrophic factors but that is strongly synergized by NT-3 and NT-4/5.

Animals↗
PubMed1991

NADPH-dependent reductive metabolism of cis-5 unsaturated fatty acids. A revised pathway for the beta-oxidation of oleic acid.

Cis-5 double bond in a fatty acid or when encountered through the beta-oxidation of an odd-numbered double-bond unsaturated fatty acid presents as a metabolic block to the further beta-oxidation. Cis-5-fatty acyl-CoA cannot be beta-oxidized to cis-3-enoyl-CoA as suggested by the conventional pathway. Instead, this metabolic block can only be removed through an NADPH-dependent reduction of 5-enoyl-CoA, possibly mediated by a 5-enoyl-CoA reductase. In the case of oleic acid two cycles of beta-oxidation yield cis-5-tetradecenoyl-CoA. This intermediate is then reduced to tetradecanoyl-CoA, which is metabolized further via normal beta-oxidation cycles. The conventional pathway through cis-3-dodecenoyl-CoA does not operate in rat liver.

Adenosine Triphosphate↗
PubMed2005

[Therapeutic effect of qingkailing and shengmai injection alone or combined on the acute lung injury induced by oleic acid in rabbits].

OBJECTIVE: To investigate the effect of Qingikailing and Shengmai injection alone or combined on the acute lung injury (AL) induced by oleic acid in rabbits. METHOD: The rabbits were randomly divided into 11 groups: oleic acid group; control group; treatment groups including low, middle and high dosage groups of Qingkailing and Shengmai injection alone and combined, respectively. ALI model was established by iv oleic acid (0.05 mL x kg(-1)) in these groups, and then iv above drugs respectively,while in control group, the same volume of normal saline was given. The respiratory amplitude and rate were observed, and blood samples were taken from cervical artery for blood-gas analysis before and at 30, 60, 120 min after oleic acid or normal saline administration. At the end of experiment, the concentration of LDH, CAT and MDA in the lung tissue were measured and pathologic changes of lung tissue were observed microscopically. RESULT: Compared with oleic acid group, the respiratory amplitude markedly enhanced (P < 0.05) in the low and high dose groups of Qingkailing and Shengmai injection. PaO2 increased significantly (P < 0.05) in the low dose group of combined Qingkailing and Shengmai injection, PaCO2 decreased markedly (P < 0.05) in the low dose groups of Qingkailing and Shengmai injection alone and combined. The level of MDA significantly decreased (P < 0.05) in the each group of Qingkailing and Shengmai injection alone, the level of MDA significantly decreased (P < 0.05) and CAT increased (P < 0.05) in the low dose group of combined Qingkailing with Shengmai injection. The low dose group of combined Qingkailing and Shengmai injection can alleviate the pathological changes induced by oleic acid. CONCLUSION: The curative effect of the low dose group of combined Qingkailing with Shengmai injection for the ALI induced by oleic acid was better than Qingkailing and Shengmai injection alone at the same dosage.

Animals↗
PubMed1996

Acute growth hormone injection reduced gastrointestinal and increased hepatic oleic acid oxidation in swine.

Gastrointestinal, hepatic, and hindleg oxidation of 3H-labelled oleic acid and 14C-labelled glucose based on arterial-venous differences in 3H2O and 14CO2 were studied before and after an intravenous injection of 24 IU of growth hormone in 10 piglets. Hepatic oleic acid oxidation increased transiently while gastrointestinal oleic acid oxidation decreased correspondingly, maintaining a constant splanchnic oleic acid oxidation. Administration of a growth hormone led to a transient, parallel decrease in both hepatic and gastrointestinal glucose oxidation. We conclude that, in contrast to the growth hormone effect on splanchnic glucose oxidation, growth hormone effect on splanchnic fat oxidation appears to be organ specific.

Animals↗
PubMed1989

Oleic acid allows more apoprotein A-1 to bind with higher affinity to large emulsion particles saturated with cholesterol.

Apoprotein (apo) A-1 binding to large triolein-rich emulsion particles saturated with cholesterol has been examined as a function of the oleic acid content. Six emulsion systems were formed containing 0.3-1.0% (by weight) oleic acid, 82.9-86.3% triolein, 10.6-7.2% egg yolk phosphatidylcholine, and 6.7-5.5% cholesterol. The average emulsion particle diameters calculated from these lipid compositions ranged between 84 and 116 nm. Negative stain electron microscopy of an emulsion containing 1% oleic acid showed a polydisperse population of only large spherical particles with a mean diameter of 116 +/- 54 nm. The calculated cholesterol concentrations of the particles surface and core for the six emulsions were 43.3 +/- 1.1 and 5.6 +/- 0.2 mol%, respectively, and were rather constant. Therefore, when the surface oleic acid concentrations increased from 2.6 to 10.1 mol%, the phospholipid concentration decreased from 55.1 to 45.9 mol%. In the core, oleic acid increased at the expense of triolein. In the range studied a nearly 4-fold increase in the surface oleic acid content produces a similar increase in the binding capacity (N) and reduces the dissociation constant (Kd). The changes in the Kd and N values were linearly dependent on the surface oleic acid concentration. These data show that oleic acid allows more apoA-1 to bind with higher affinity to large emulsion particles saturated with cholesterol.

Apolipoprotein A-I↗
PubMed1999

Effects of dietary fats (fish, olive and high-oleic-acid sunflower oils) on lipid composition and antioxidant enzymes in rat liver.

The effects of two oleic-acid-rich diets (containing olive oil, OO, and high-oleic-acid sunflower oil, HOSO) on plasma and liver lipid composition detoxification enzyme activities, were compared with those of a fish-oil (FO) diet and a control diet. Compared with the control diet, plasma and hepatic total triacylglycerol concentrations were increased in the animals fed on the HOSO and OO diets and decreased in those fed on the FO diet. The animals fed on FO showed the highest level of cholesterol in the liver and had lower plasma cholesterol concentrations when compared with those fed on the two oleic-acid-rich diets. In comparison with the animals fed on the diets enriched in oleic acid, the FO group showed higher hepatic levels of polyunsaturated fatty acids of the n-3 series and lower levels of fatty acids of the n-6 series. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (1) significantly higher activities of catalase (EC 1.11.1.6) glutathione peroxidase (EC 1.11.1.9) and Cu/Zn superoxide dismutase (EC 1.15.1.1); (2) no differences in the NADPH-cytochrome c reductase (EC 1.6.99.3) activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the efficiency of the antioxidant defence system. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid but different contents of natural antioxidants, had similar effects on the antioxidant enzyme activities measured.

Analysis of Variance↗
PubMedDate not supplied

[The role of oleic acid in the process of induced destruction of Escherichia coli M-17].

The influence of oleic acid on the process of the destruction of E. coli, induced by the transfer of the bacteria from the growth medium into solution without nutrient substances and their treatment with oleic acid at a temperature of 45 degrees C, was studied. Oleic acid at a concentration of 200 nmol/ml accelerated the destruction of E. coli in comparison with the control organisms, but did not lead to the significant increase of the final degree of the destruction of biomass. The dynamics of the inclusion of labeled oleic acid into E. coli cell fractions after the induction of autolysis was analyzed. The radioactive label was most actively included into the lipid (chloroform) fraction of bacterial biopolymers. Simultaneously with the destruction of some cells in the population the inclusion of labeled oleic acid into intact cells was found to occur.

Bacteriolysis↗
PubMed2005

[Therapeutic effect of Qingkailing and methylprednisolone injection alone or combined on the acute lung injury induced by oleic acid in rabbits].

OBJECTIVE: To investigate the effect of Qingkailing and Methylprednisolone (MP) injection alone or combined on the acute lung injury (ALI) induced by oleic acid in rabbits. METHOD: The rabbits were randomly divided into 11 groups: oleic acid group; control group; treatment groups including low, middle and high dosage groups of Qingkailing and MP alone and combined, respectively. ALI model was established by i.v. oleic acid (0.05 mL x kg(-1)) in these groups, and then i.v. above drugs respectively, while in control group, the same volume of normal saline was given. The respiratory amplitude and rate were observed, and blood samples were taken from cervical artery for blood-gas analysis before and at 30, 60, 120 min after oleic acid or normal saline administration. At the end of experiment, the concentration of LDH, CAT and MDA in the lung tissue were measured and pathologic changes of lung tissue were observed microscopically. RESULT: Compared with oleic acid group, the respiratory amplitude markedly enhanced (P < 0.05) and respiratory rate lowered (P < 0.05) in the low, middle and high dose groups of Qingkailing and MP injection. On the 30 min of treatment, PaO2 increased significantly (P < 0.05) in the low and middle dose groups of combined Qingkailing and MP injection; PaCO2 decreased markedly (P < 0.05) on the 120 min of treatment in each treatment group. The level of LDH significantly increased (P < 0.05), CAT and MDA decreased (P < 0.05) in the middle and high groups of Qingkailing and MP injection. The low and middle dose groups of combined Qingkailing and MP injection can alleviate the pathological changes induced by oleic acid. CONCLUSION: The curative effect of the low dose group of combined Qingkailing and MP for the ALI induced by oleic acid was better than Qingkailing and MP alone, while the big dose groups of Qingkailing and MP alone better than the combination at the same dosage.

Animals↗
PubMed2003

Oleic acid induces endothelin-1 expression through activation of protein kinase C and NF-kappa B.

This study investigated the effect of oleic acid on the expression levels of endothelin-1 (ET-1) and on the signaling pathways mediating it in human aortic endothelial cells (HAECs). ET-1 mRNA expression was significantly increased by oleic acid in a dose- and time-dependent manner. Elevation of ET-1 expression in response to oleic acid was inhibited by the protein kinase C (PKC) inhibitor, GF109203X, or the NF-kappa B inhibitor, pyrrolidine dithiocarbamate. In addition, both PKC and NF-kappa B activities were significantly increased by oleic acid. Immunoblot analysis revealed that conventional PKCs (PKC-alpha and -beta II isoforms) were significantly increased in the membranous fractions of HAECs treated with oleic acid. PKC inhibitor completely abolished oleic acid-induced NF-kappa B activation, suggesting that PKC activation is upstream of NF-kappa B activation in oleic acid-induced ET-1 expression. These data suggest that elevated plasma oleic acid levels observed in obese, insulin-resistant subjects result in endothelial dysfunction, at least in part, through an increase in ET-1 expression.

Cells, Cultured↗
PubMed1975

Turnover of plasma free stearic and oleic acids in resting and exercising human subjects.

Turnover rates and metabolism in the legs and the splanchnic region of free stearic and oleic acid have been studied in five healthy male volunteers at rest and during bicycle exercise. A continuous infusion of 14C-labeled stearic acid and tritiated oleic acid was given intravenously. At rest, the fractional turnover was the same for the two acids; the fractional leg uptakes were also similar, while fractional uptake in the splanchnic region was 80% higher for oleic than for stearic acid. The response to exercise differed between the two acids: the arterial concentration of stearic acid fell, its fractional turnover and fractional leg uptake became higher than for oleic acid, and its fractional uptake in the splanchnic region increased, while that of oleic acid remained unchanged. It is concluded (1) that stearic acid turnover in the postabsorptive state is similar to that of the main part of the FFA fraction and (2) that the decrease in stearic acid concentration during exercise can be explained by an increased removal in excess of that for other FFA.

Adult↗
PubMed1992

Biphasic effect of oleic acid on hepatic cholesterogenesis.

Livers isolated from adult male rats were perfused in vitro with oleic acid (0.6 mM) as a complex with bovine serum albumin. Albumin alone was infused in control experiments. Oleic acid exerted a biphasic effect on incorporation of 3H2O into cholesterol, which was inhibitory during the first hour of perfusion, but exhibited a net stimulatory effect over a four hour period. No differences were observed in total activity or apparent phosphorylation state of HMG-CoA reductase after one hour of perfusion, with or without addition of oleic acid, implying that some other step limits the rate of cholesterol synthesis during this interval. After four hours of perfusion, HMG-CoA reductase activity was higher in livers perfused with oleic acid than in those perfused in its absence, in agreement with the observed differences in rates of cholesterol synthesis.

Animals↗
PubMed2001

Effect of a low-fat diet enriched with oleic acid on postprandial lipemia in patients with type 2 diabetes mellitus.

The aim of the present study was to compare the effects of a low-fat diet enriched with oleic acid to those of a low-fat diet enriched with linoleic acid on fasting lipids, postprandial lipemia, and oxidative susceptibility of low-density lipoprotein (LDL) in patients with type 2 diabetes mellitus (DM). In a 3-wk randomized crossover study, eight patients with type 2 DM were given an experimental low-fat diet enriched with either oleic acid or linoleic acid. The oleic-acid-enriched diet contained 5, 15, and 5%, energy from saturated, monounsaturated, and polyunsaturated fatty acids, and the linoleic-acid-enriched diet contained 5, 5, and 15% energy from saturated, monounsaturated, and polyunsaturated fatty acids, respectively. In addition to evaluating the fasting lipids and oxidative susceptibility of LDL, we evaluated postprandial lipemia using an oral fat load at the end of each 3-wk dietary phase. There were no significant differences in fasting lipid profile or lag time of LDL oxidation between the two experimental dietary phases. The average and maximal increments of remnant-like particle (RLP) cholesterol levels during oral fat load were significantly higher after the oleic-acid-enriched dietary phase than after the linoleic-acid-enriched dietary phase. The area under the curve of RLP cholesterol was also significantly larger after the oleic-acid-enriched dietary phase than after the linoleic-acid-enriched dietary phase. These results suggest that the oleic-acid-enriched diet was associated with increased formation of postprandial chylomicron remnants compared with the linoleic-acid-enriched diet.

Aged↗
PubMed1999

A yeast strain defective in oleic acid utilization has a mutation in the RML2 gene.

The molecular mechanisms of cellular long-chain fatty acid assimilation and its regulation remain unclear. In an attempt to identify essential mediators of these processes, we have isolated mutant strains of the yeast Saccharomyces cerevisiae unable to utilize oleic acid as sole carbon source, while retaining the ability to utilize acetate. These strains are then subjected to several secondary screening assays to identify mutants of interest. Here we describe a mutant (denoted fat21) that, despite a temperature-sensitive inability to utilize oleic acid as sole carbon source, displays no general defect in oleic acid uptake or incorporation of oleic acid into glycerolipids. Oxidation of acetate after growth in acetate medium is increased similarly in the mutant and parent strains. Oleic acid beta-oxidation in acetate grown cells is also comparable between strains. Induction of oleic acid oxidation following exposure to oleic acid is, however, defective in the fat21 mutant. The fat21 mutant allele displays conditional synthetic lethality in combination with a null allele of the OLE1 gene, which encodes Delta9-desaturase and is required for proper mitochondrial segregation. Clones capable of complementing the fat21 defect contained the RML2 gene, encoding a yeast mitochondria ribosomal protein. Segregation analysis and gene replacement experiments demonstrate that RML2 is the gene defective in the fat21 mutant. These observations of a defect in a mitochondrial protein differentially affecting the adaptation to oleic acid and acetate as carbon sources suggest that the phenotype of fat21 is associated with a novel pathway of mitochondrial-nuclear-peroxisomal communication.

Alleles↗