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PubMed1991

Unique fatty acid composition of normal cartilage: discovery of high levels of n-9 eicosatrienoic acid and low levels of n-6 polyunsaturated fatty acids.

We report here the finding that normal, young cartilages, in distinction from all other tissues examined, have unusually high levels of n-9 eicosatrienoic (20:3 cis-delta 5,8,11) acid and low levels of n-6 polyunsaturated fatty acids (n-6 PUFA). This pattern is identical to that found in tissues of animals subjected to prolonged depletion of nutritionally essential n-6 polyunsaturated fatty acids (EFA). This apparent deficiency is consistently observed in cartilage of all species so far studied (young chicken, fetal calf, newborn pig, rabbit, and human), even though levels of n-6 PUFA in blood and all other tissues is normal. The n-9 20:3 acid is particularly abundant in phosphatidylethanolamine, phosphatidylinositol, and the free fatty acid fractions from the young cartilage. Several factors appear to contribute to the reduction in n-6 PUFA and the appearance of high levels of the n-9 20:3 acid in cartilage: 1) limited access to nutritional sources of EFA due to the impermeability and avascularity of cartilage, 2) rapid metabolism of n-6 PUFA to prostanoids by chondrocytes, and 3) a unique fatty acid metabolism by cartilage. Evidence is presented that each of these factors contributes. Previously, EFA deficiency has been shown to greatly suppress the inflammatory response of leukocytes and rejection of tissues transplanted into allogeneic recipients. Because eicosanoids, which are derived from EFA, have been implicated in the inflammatory responses associated with arthritic disease, reduction of n-6 PUFA and accumulation of the n-9 20:3 acid in cartilage may be important for maintaining normal cartilage structure.

8,11,14-Eicosatrienoic Acid↗
PubMed2005

Exogenous isoleucine and fatty acid shortening ensure the high content of anteiso-C15:0 fatty acid required for low-temperature growth of Listeria monocytogenes.

Previous studies have demonstrated that the branched-chain fatty acid anteiso-C15:0 plays a critical role in the growth of Listeria monocytogenes at low temperatures by ensuring sufficient membrane fluidity. Studies utilizing a chemically defined minimal medium revealed that the anteiso fatty acid precursor isoleucine largely determined the fatty acid profile and fatty acid response of the organism to lowered growth temperature. When isoleucine was sufficient, the fatty acid profile was very uniform, with anteiso fatty acids comprising up to 95% of total fatty acid, and the major fatty acid adjustment to low temperature was fatty acid chain shortening, which resulted in an increase of anteiso-C15:0 solely at the expense of anteiso-C17:0. When isoleucine was not supplied, the fatty acid profile became more complex and was readily modified by leucine, which resulted in a significant increase of corresponding iso fatty acids and an inability to grow at 10 degrees C. Under this condition, the increase of anteiso-C15:0 at low temperature resulted from the combined effect of increasing the anteiso:iso ratio and chain shortening. A branched-chain alpha-keto acid dehydrogenase-defective strain largely lost the ability to increase the anteiso:iso ratio. Cerulenin, an inhibitor of beta-ketoacyl-acyl carrier protein synthase (FabF), induced a similar fatty acid chain shortening as low temperature did. We propose that the anteiso precursor preferences of enzymes in the branched-chain fatty acid biosynthesis pathway ensure a high production of anteiso fatty acids, and cold-regulated chain shortening results in a further increase of anteiso-C15:0 at the expense of anteiso-C17:0.

Base Sequence↗
PubMed1988

Fat pad triacylglycerol fatty acid loss and oxidation as indices of total body triacylglycerol fatty acid mobilization and oxidation in starving mice.

We tested our hypothesis that, kinetically, triacylglycerol fatty acids in heterogeneously labeled adipocytes behave similarly to the whole fat pad triacylglycerol fatty acid during starvation in mice. Adipose triacylglycerol fatty acids were labeled with [1-14C]palmitate (complexed to albumin) by injection of a small bolus (2-5 microliter) into either epididymal or inguinal fat pads. Both 14C-labeled triacylglycerol fatty acid spec. act. and breath 14CO2 spec. act. were monitored 30 min after tracer injection and after 24-72 h starvation. Adipose triacylglycerol fatty acid spec. act. remained approximately constant during fasting, i.e., tracer and mass disappeared at similar rates. Negligible translocation of labeled triacylglycerol fatty acid from the injection site to other parts of the same fat pad or to distant fat pads occurred. Triacylglycerol fatty acid was mobilized more slowly from epididymal than from inguinal fat pads in two of three studies. Triacylglycerol fatty acid disappearance (loss) from inguinal fat pads was more replicable than from epididymal fat pads and more closely reflected the fall in whole body total lipid during starvation. The estimated percent of breath CO2-carbon derived from adipose triacylglycerol fatty acid increased from an average of approx. 32% in the postabsorptive state to about 77% after 48 h starvation. The data help to validate the direct tracer injection technique as a means of studying adipose triacylglycerol fatty acid turnover and oxidation. This approach should be particularly useful for studying the fate of adipose triacylglycerol fatty acid when it is mobilized. e.g., during states of inanition and starvation and in response to hormones and cancer-induced cachexia.

Adipose Tissue↗
PubMedDate not supplied

Regulation of gene expression by fatty acids: special reference to fatty acid-binding protein (FABP).

During the last years, the direct involvement of lipidic nutrients in the regulation of genes has been established. Fatty acids may induce or repress the transcription rate of several genes involved in both lipid and carbohydrate metabolisms. Gene up-regulation has been found in various tissues including liver, adipose tissue and small intestine. It is only triggered by saturated and unsaturated long-chain fatty acids or their CoA-derivatives. In contrast, gene down-regulation appears to be restricted to the liver. This negative effect is exerted only by polyunsaturated fatty acids. Long-chain fatty acids are able to regulate the expression of two different genes oppositely in the same cell type. The molecular mechanism of these fatty acid-mediated effects remains unclear. The involvement of members of the peroxisome proliferator-activated receptor is discussed.

Adipocytes↗
PubMed1984

Effect of dietary depletion and repletion of linoleic acid on renal fatty acid composition and urinary prostaglandin excretion.

To study the effect of dietary modification on urinary prostaglandin E (UPGE) excretion and on renal fatty acid compositions, weanling male rats were raised on a fat-free diet for 6 weeks and were switched to a diet containing 2 energy % of linoleic acid (LA) for 8 days. During fat deprivation, UPGE excretion increased in the first week (6.9 ng/24 hours urine), fell to a minimum of 1.1 ng/24 hours at 3rd week and thereafter remained at a level lower than that in the controls (3.1 ng/24 hours). UPGE excretion returned rapidly to normal (2.7 ng/hr) only 24 hours after LA supplementation. During LA treatment, arachidonic acid (AA) concentrations in renal cholesteryl esters rapidly increased from 19% to 27% (33% in the controls), while concentrations in renal phospholipids (PL) and renal free fatty acids (FFA) did not change during the first four days but reached the normal range at the 8th day. The present studies demonstrate that chronically fat deficient animals excreted significantly less UPGE than that in the controls. However, this deficiency could be rapidly reversed by LA supplementation despite the fact that AA levels in renal lipid fractions remained well below normal. This suggests that dietary LA may be rapidly converted to AA and subsequently to PGE without AA levels rising in the lipid fractions usually thought of as being PG precursors.

Animals↗
PubMed1986

Influence of different dietary fatty acid sources on erythrocyte lipids and plasma and liver essential fatty acids in hamsters fed ethanol.

Hamsters fed ethanol were given three different dietary sources of essential fatty acids; safflower oil, evening primrose oil (both mainly n-6 fatty acids) or linseed oil (mainly n-3 fatty acids). After 7 weeks, plasma, erythrocyte and liver lipids and fatty acids were analyzed. Plasma and liver lipids were not significantly different in the ethanol-fed hamsters compared to the controls. Erythrocyte total phospholipid was increased only in the ethanol-fed groups given n-6 but not n-3 fatty acids. Some fatty acid changes induced by ethanol were predictable, e.g. lower 20:4 n-6 in hamsters fed n-6 fatty acids, but others were not predictable, e.g. higher 22:6 n-3 in all the ethanol-fed groups. The effect of ethanol on hamster lipids and fatty acid composition appears dependent on the predominant class of dietary fatty acids.

Alcohol Drinking↗
PubMed2002

The same rat Delta6-desaturase not only acts on 18- but also on 24-carbon fatty acids in very-long-chain polyunsaturated fatty acid biosynthesis.

The recently cloned Delta6-desaturase is known to catalyse the first step in very-long-chain polyunsaturated fatty acid biosynthesis, i.e. the desaturation of linoleic and alpha-linolenic acids. The hypothesis that this enzyme could also catalyse the terminal desaturation step, i.e. the desaturation of 24-carbon highly unsaturated fatty acids, has never been elucidated. To test this hypothesis, the activity of rat Delta6-desaturase expressed in COS-7 cells was investigated. Recombinant Delta6-desaturase expression was analysed by Western blot, revealing a single band at 45 kDa. The putative involvement of this enzyme in the Delta6-desaturation of C(24:5) n-3 to C(24:6) n-3 was measured by incubating transfected cells with C(22:5) n-3. Whereas both transfected and non-transfected COS-7 cells were able to synthesize C(24:5) n-3 by elongation of C(22:5) n-3, only cells expressing Delta6-desaturase were also able to produce C(24:6) n-3. In addition, Delta6-desaturation of [1-(14)C]C(24:5) n-3 was assayed in vitro in homogenates from COS-7 cells expressing Delta6-desaturase or not, showing that Delta6-desaturase catalyses the conversion of C(24:5) n-3 to C(24:6) n-3. Evidence is therefore presented that the same rat Delta6-desaturase catalyses not only the conversion of C(18:3) n-3 to C(18:4) n-3, but also the conversion of C(24:5) n-3 to C(24:6) n-3. A similar mechanism in the n-6 series is strongly suggested.

Animals↗
PubMed1997

Fatty acid binding proteins reduce 15-lipoxygenase-induced oxygenation of linoleic acid and arachidonic acid.

Free fatty acids in plasma and cells are mainly bound to membranes and proteins such as albumin and fatty acid binding proteins (FABP), which can regulate their biological activities and metabolic transformations. We have investigated the effect of FABP and albumin on the peroxidation of linoleic acid (18:2) and arachidonic acid (20:4) by 15-lipoxygenase (15-LO). Rabbit reticulocyte 15-LO produced a rapid conversion of [1-14C]18:2 to 13-hydroxyoctadecadienoic acid (13-HODE) and [3H]20:4 to 15-hydroxyeicosatetraenoic acid (15-HETE). 13-HODE formation was reduced when intestinal FABP (I-FABP). liver FABP (L-FABP) or albumin was added. The relative ability of these proteins to reduce 15-LO induced formation of 13-HODE and 15-HETE was BSA > L-FABP > I-FABP. Smaller reductions in activity were observed with 20:4 as compared to 18:2. The IC50-values of I-FABP and L-FABP, using either 18:2 (3.4 microM) or 20:4 (3.4 microM), were 4.6 +/- 0.6 and 1.9 +/- 0.2 microM, respectively, for reduction of 13-HODE and 6.8 +/- 0.3 and 3.1 +/- 0.2 microM, respectively, for reduction of 15-HETE formation. The smaller 15-HETE reduction correlated with decreased binding of 20:4 to the FABP. Titration calorimetry also showed that the I-FABP IC50 for 18:2, 0.25 microM, was lower then for 20:4, 0.6 microM. Thus the reduction in fatty acid lipid peroxidation relates to the binding capacity of each FABP. We also demonstrated that 18:2 rapidly diffuses (flip-flops) across the phospholipid bilayer of small unilamellar vesicles (SUV) and measured partitioning of 18:2 between proteins and SUV by the pyranin fluorescence method [Kamp, F. and Hamilton, J.A. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 11367-11370]. Addition of proteins to SUV in buffer resulted in a complete desorption of 18:2 from SUV with a relative effect of BSA > L-FABP > I-FABP. This suggests that the relative effects of these proteins on 18:2 peroxidation will not be altered by the presence of membranes. Our results indicate that FAPBs protect intracellular polyunsaturated fatty acids against peroxidation and, through differential binding of 18:2 and 20:4, they may modulate the availability of these polyunsaturated fatty acids to intracellular oxidative pathways.

Animals↗
PubMed2003

Fatty acid content of margarines in the Greek market (including trans-fatty acids): a contribution to improving consumers' information.

The fatty acid composition, including trans-fatty acids, of 15 margarine samples from the Greek market was determined by gas-liquid chromatography. Saturated, cis-monounsaturated and polyunsaturated fatty acids have been found in the ranges of 24.1-53.3%, 15.5-50.3%, and 14.3-50.2% of total fatty acids, respectively. The trans-fatty acid content of Greek margarines varied from 0.1 to 19% and was, on the average, lower than previously reported. The high content in saturated fatty acids of the samples examined is criticized. There is significant discrepancy between fatty acid composition and the description of the product on the label. A concise index to describe fatty acid composition is proposed. This index can appear on the label and would give the consumers a much more accurate picture of the fatty acid composition.

Chromatography, Gas↗
PubMed2001

Effect of fatty acids on phase behavior of hydrated dipalmitoylphosphatidylcholine bilayer: saturated versus unsaturated fatty acids.

The effect of some fatty acids on the phase behavior of hydrated dipalmitoylphosphatidylcholine (DPPC) bilayer was investigated with special interest in possible difference between saturated and unsaturated fatty acids. The phase behavior of hydrated DPPC bilayer was followed by a differential scanning calorimetry and a Fourier transform infrared spectroscopy. The addition of palmitic acid (PA) increased the bilayer phase transition temperature with the increase of the PA content in the mixture. In addition, DPPC molecules in gel phase bilayer became more rigid in the presence of PA compared with those in the absence of PA. This effect of PA on the phase behavior of hydrated DPPC bilayer is common to other saturated fatty acids, stearic acid, myristic acid, and also to unsaturated fatty acid with trans double bond, elaidic acid. Contrary to these fatty acids, oleic acid (OA), the unsaturated fatty acid with cis double bond in the acyl chain, exhibited quite different behavior. The effect of OA on the bilayer phase transition temperature was rather small, although a slight decrease in the temperature was appreciable. Furthermore, the IR spectral results demonstrated that the perturbing effect of OA on the gel phase bilayer of DPPC was quite small. These results mean that OA does not disturb the hydrated DPPC bilayer significantly.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1992

Effects of essential fatty acid contents of lipid emulsions on erythrocyte polyunsaturated fatty acid composition in patients on long-term parenteral nutrition.

The effect of the long-term intravenous infusion of 2 lipid emulsions, differing in essential fatty acid (EFA) content, on fatty acid pattern of red blood cell (RBC) was investigated in 5 patients with inflammatory bowel disease. They were randomly assigned to receive daily intravenous infusion of either a soybean emulsion or a mixed medium-chain triacyl-glycerols (MCT): soybean emulsion, followed by the other, each for a period of 3 months. The soybean emulsion contained exclusively long-chain triacylglycerols (LCT) with 54% of C18:2n-6 and 6% of C18:3n-3. The mixed emulsion consisted of a 50:50 (w:w) mixture of soybean LCT and MCT, providing half the amount of the same EFA compared to LCT emulsion. The same phospholipid emulsifier was used in both preparations. Infusion of LCT for a 3 month period modified RBC fatty acid pattern as follows: 18:2n-6 increased, 20:4n-6 decreased as well as n-6:n-3 ratio. By contrast, infusion of MCT/LCT did not alter RBC fatty acids, and even tended to correct a pattern altered by the previous LCT infusion. The study demonstrates that soybean LCT provides an excess of C18: 2n-6 which affects the balance between RBC fatty acids in adult patients. Decreasing the intake of C18:2n-6 and C18: 3n-3, by using a mixed MCT/LCT emulsion, appears more appropriate for keeping a balanced pattern.

Journal Article↗
PubMed1992

Dietary fatty acids temporarily alter liver very long-chain fatty acid composition in mice.

To determine the influence of dietary fatty acids on tissue very long-chain fatty acid (VLFA) composition, mice were fed four diets containing 15 g fat/100 g diet derived largely from either safflower oil, peanut oil, olive oil or glycerol trioleate oil. The diets varied widely in the composition of VLFA and other fatty acids. Digestibility of total dietary VLFA ranged from 84.6% in mice fed the glycerol trioleate diet to 96.7% in those fed the safflower oil diet. After 3 mo, the saturated VLFA composition of liver total lipids and sphingomyelin was lower in animals fed the glycerol trioleate oil diet than in mice fed most other diets. Although the saturated VLFA content of the peanut oil diet was more than 15-fold greater than that of the other diets, animals fed the peanut oil diet showed little or no selective increase in liver saturated VLFA. The VLFA composition of brain was comparable in all dietary groups. After 8 mo of feeding, the liver saturated VLFA composition tended to increase and differences between groups disappeared. Liver peroxisomal beta-oxidation of lignocerate (24:0) was similar among all dietary groups. These results demonstrate that dietary fatty acids shorter than VLFA temporarily influence the saturated VLFA composition of liver.

Animals↗
PubMed1997

Prediagnostic level of fatty acids in serum phospholipids: omega-3 and omega-6 fatty acids and the risk of prostate cancer.

Ecological and case-control studies have demonstrated a positive correlation between consumption of fat and the risk of prostate cancer. Two recent human studies have focused on alpha-linolenic acid as a risk factor for prostate cancer. Animal experiments have shown that dietary omega-6 polyunsaturated fatty acids have generally stimulated tumour development, whereas omega-3 polyunsaturated fatty acids have diminished it. The aim of our study was to investigate the association between these fatty acids and the subsequent risk of prostate cancer. Blood donors to the Janus serum data bank in Norway, who later developed prostate cancer, were matched to blood donors without prostate cancer (141 matched sets); the proportional level of fatty acids measured before diagnosis in the donors' serum was examined. The risk of later prostate cancer was analysed by conditional logistic regression. Increasing risk for prostate cancer was found with increasing quartiles of palmitoleic, palmitic and alpha-linolenic acid. An inverse risk association was found with increasing levels of tetracosanoic acid, for the ratios of linoleic to alpha-linolenic acid and arachidonic to eicosapentaenoic acid. There was no clear association between the risk effect of total omega-3 and total omega-6 fatty acids. There were no indications of a relationship between fatty acids and more aggressive cancers. Our results verify recent findings of a positive association between alpha-linolenic acid and a negative association between the ratio of linoleic to alpha-linolenic acid and the risk of prostate cancer.

Case-Control Studies↗
PubMed1988

Fatty acid components of larval Ostrea edulis (L.): importance of triacylglycerols as a fatty acid reserve.

1. The fatty acid profiles of all of the acyl-lipid classes of 1- and 10-day-old European oyster Ostrea edulis (L.) larvae were studied in detail by capillary gas-liquid chromatography. 2. No significant changes in the fatty acids were detected between the different larval stages. 3. Total lipid fatty acids showed a higher degree of unsaturation than previously reported. This may be a consequence of the extraction of lipids from the living tissues without sample storage. 4. One-third of the triacylglycerol fatty acids were polyunsaturated. In agreement with the importance of triacylglycerols in lipids of bivalve larvae, it is suggested that this lipid fraction may act as a temporary reservoir of physiologically-important polyunsaturated fatty acids. 5. Free fatty acids and fatty acids from the minor lipid classes are discussed in terms of their possible origin and physiological significances.

Animals↗
PubMed1990

Purification of the multienzyme complex for fatty acid oxidation from Pseudomonas fragi and reconstitution of the fatty acid oxidation system.

The multienzyme complex for fatty acid oxidation was purified from Pseudomonas fragi, which was grown on oleic acid as the sole carbon source. This complex exhibited enoyl-CoA hydratase [EC 4.2.1.17], 3-hydroxyacyl-CoA dehydrogenase [EC 1.1.1.35], 3-oxoacyl-CoA thiolase [EC 2.3.1.16], cis-3,trans-2-enoyl-CoA isomerase [EC 5.3.3.3], and 3-hydroxyacyl-CoA epimerase [EC 5.1.2.3] activities. The molecular weight of the native complex was estimated to be 240,000. Two types of subunits, with molecular weights of 73,000 and 42,000, were identified. The complex was composed of two copies each of the 73,000- and 42,000-Da subunits. The beta-oxidation system was reconstituted in vitro using the multienzyme complex, acyl-CoA synthetase and acyl-CoA oxidase. This reconstituted system completely oxidized saturated fatty acids with acyl chains of from 4 to 18 carbon atoms as well as unsaturated fatty acids having cis double bonds extending from odd-numbered carbon atoms. However, unsaturated fatty acids having cis double bonds extending from even-numbered carbon atoms were not completely oxidized to acetyl-CoA: about 5 mol of acetyl-CoA was produced from 1 mol of linoleic or alpha-linolenic acid, and about 2 mol of acetyl-CoA from 1 mol of gamma-linolenic acid. These results suggested that the 3-hydroxyacyl-CoA epimerase in the complex was not operative. When the epimerase was by-passed by the addition of 2,4-dienoyl-CoA reductase to the reconstituted system, unsaturated fatty acids with cis double bonds extending from even-numbered carbon atoms were also completely degraded to acetyl-CoA.

Animals↗