Modulation of plasma N-acylethanolamine levels and physiological parameters by dietary fatty acid composition in humans

N-acylethanolamines (NAEs) are endogenous lipid-signaling molecules involved in satiety and energetics; however, how diet impacts circulating NAE concentrations and their downstream metabolic actions in humans remains unknown. Objectives were to examine effects of diets enriched with high-oleic canola oil (HOCO) or HOCO blended with flaxseed oil (FXCO), compared with a Western diet (WD), on plasma NAE levels and the association with energy expenditure and substrate oxidation. Using a randomized controlled crossover design, 36 hypercholesterolemic participants consumed three isoenergetic diets for 28 days, each containing 36% energy from fat, of which 70% was HOCO, FXCO, or WD. Ultra-performance liquid chromatography-MS/MS was used to measure plasma NAE levels and indirect calorimetry to assess energy expenditure and substrate oxidation. After 28 days, compared with WD, plasma oleoylethanolamide (OEA) and alpha-linolenoyl ethanolamide (ALEA) levels were significantly increased in response to HOCO and FXCO (P = 0.002, P < 0.001), respectively. Correlation analysis demonstrated an inverse association between plasma OEA levels and percent body fat (r = −0.21, P = 0.04), and a positive association was observed between the plasma arachidonoyl ethanolamide (AEA)/OEA ratio and android:gynoid fat (r = 0.23, P = 0.02), respectively. Results suggest that plasma NAE levels are upregulated via their dietary lipid substrates and may modulate regional and total fat mass through lipid-signaling mechanisms.     

Effect of heat inactivation and freezing on fatty acid composition of plasma and red blood cells.

The effect of heat inactivation and freezing on fatty acid composition of plasma and red blood cells was investigated. Analysis was completed at baseline; after freezing; after incubation; after incubation and subsequent freezing; after incubation, freezing and a second incubation; and after freezing and subsequent incubation. There were changes in fatty acid levels observed in all groups with the phospholipid fractions showing the greatest changes. Those bloods that had been incubated, frozen and incubated again, and those which had been frozen initially followed by incubation showed the greatest change when compared to baseline samples. Even though there were changes in fatty acid levels seen in all groups, the changes were small except in those two groups. Treatment of blood with either of those two treatment regimens changes the fatty acid values so that they do not accurately reflect the composition of fatty acids in the blood.     

Changes in fatty acid composition of thymus cells, liver, blood plasma, and muscle tissue in mice with solid Ehrlich carcinoma

The fatty acid composition of thymus cells, liver, blood plasma, muscle tissue, and tumor focus has been studied in mice with solid Ehrlich carcinoma. The tumor growth in the mice was associated with an increase in the total content of monounsaturated fatty acids in all organs and tissues studied and with a decrease in the total amount of polyunsaturated fatty acids in all tissues except blood plasma. The tumor tissue was characterized by increased levels of monounsaturated fatty acids in comparison with their levels in organs and tissues of intact animals. In the thymus of tumor-bearing mice, the contents of myristic and palmitic saturated fatty acids, which are associated with activation of the T-cell immunity, were increased. The most expressed and considerable changes in the fatty acid composition during tumor growth were observed in the muscle tissue of the animals. A possible role of changes in the fatty acid composition in the investigated organs and tissues of tumor-bearing mice in the organism’s response to tumor growth is discussed.     

Fatty acid omega-oxidation as a rescue pathway for fatty acid oxidation disorders in humans

Fatty acids (FAs) can be degraded via different mechanisms including α-, β- and ω-oxidation. In humans, a range of different genetic diseases has been identified in which either mitochondrial FA β-oxidation, peroxisomal FA β-oxidation or FA α-oxidation is impaired. Treatment options for most of these disorders are limited. This has prompted us to study FA ω-oxidation as a rescue pathway for these disorders, based on the notion that if the ω-oxidation of specific FAs could be upregulated one could reduce the accumulation of these FAs and the subsequent detrimental effects in the different groups of disorders. In this minireview, we describe our current state of knowledge in this area with special emphasis on Refsum disease and X-linked adrenoleukodystrophy.     

Dietary fat,fatty acid composition in plasma and the metabolic syndrome

PURPOSE OF REVIEW: The metabolic syndrome, a cluster of disorders often including abdominal obesity, is associated with a high risk of cardiovascular disease and premature death. Insulin resistance is a key feature of the metabolic syndrome. Observational studies have indicated that the type of fat in the diet may be related to the development of insulin resistance and the metabolic syndrome, also independent of possible effects on body weight. Dietary surveys are often imprecise. One way to monitor the type of fat in the diet is to record the fatty acid composition in plasma. This review summarizes recent data on the relationships between fatty acid composition in plasma and insulin resistance, diabetes and other disorders related to the metabolic syndrome. RECENT FINDINGS: Insulin resistance and insulin resistant states are often associated with the fatty acid pattern in plasma, characterized by an increased proportion of palmitic (16 : 0) and a low proportion of linoleic (18 : 2 n-6) acids, with a distribution of other fatty acids indicating an increased activity of delta-9 and delta-6 desaturase. This shows that there may be a causal relationship between the type of fat in the diet and insulin action, an assumption supported by recent dietary intervention studies. SUMMARY: In a public health perspective these results, from both observational and intervention studies, underline the importance of fat quality in the diet for the development of a number of prevalent diseases. Taken together with several earlier studies and recent epidemiological findings, they give strong support to present dietary guidelines.     

Fatty acid composition and lipoxygenase metabolism in blood cells of the lesser spotted dogfish, Scyliorhinus canicula.

1. The fatty acid composition of erythrocytes and leucocytes of the elasmobranch, Scyliorhinus canicula, was determined so as to indicate substrate availability for eicosanoid formation. 2. Leucocytes showed a greater degree of fatty acid unsaturation than the erythrocytes, with particularly high levels of docosahexaenoic acid (22:6,n-3). 3. The major eicosanoid precursors, arachidonic acid (20:4,n-6) and eicosapentaenoic acid (20:5,n-3), represented 13.9% and 5.2% of the total fatty acid, respectively, in erythrocytes compared with 10.7% and 6% in leucocytes. 4. Whole blood and isolated leucocytes were stimulated with calcium ionophore, A23187 and the resulting lipoxygenase products separated by reverse phase high performance liquid chromatography. 5. The main lipoxygenase products formed were 6-trans-leukotriene B4, 6-trans-12-epi-leukotriene B4, 5(S),6(R) dihydroxyeicosatetraenoic acid and 5- and 15-hydroxyeicosatetraenoic acid. 6. No leukotriene B4, leukotriene B5, or lipoxins were detected.     

Fatty acid desaturation and microsomal lipid fatty acid composition in experimental hypothyroidism.

We have studied the influence of experimental hypothyroidism in the rat on the synthesis of unsaturated fatty acids and on liver microsomal lipid fatty acid composition. Hypothyroid rats demonstrated an 80% decrease in delta 9 (stearate) desaturation and a 43% decrease in delta 6 (linoleate) desaturation. Liver microsomal fatty acid composition was altered in the hypothyroid animals with a significantly decreased proportion of arachidonate and increased proportions of linoleate, eicosa-8,11,14-trienoate, eicosapentaenoate and docosahexaenoate. The bulk of these changes occurred in both of the two major phospholipid components, phosphatidylcholine and phosphatidylethanolamine. All of the changes were corrected by treatment of the hypothyroid rat with 25 micrograms of tri-iodothyronine/100 g body wt. twice daily. The diminished delta 9 desaturation did not lead to any changes in fatty acid composition. The increased linoleate and decreased arachidonate levels may be due to the diminished delta 6 desaturase activity, the rate-controlling step in the conversion of linoleate into arachidonate. The increases in the proportions of the other polyunsaturated fatty acid components cannot be explained by changes in the synthesis of unsaturated fatty acids, but are probably due to diminished utilization of these fatty acids.     

Comparative characteristics of the fatty acid composition of lipoproteins in human blood plasma and aortic wall]

A study was made of a fatty acid composition of individual lipid fractions in the lipoproteids of the blood serum of a very low, low and high density, and the wall of the aorta affected with atherosclerosis. There was a close similarity between a fatty acid composition of phospholipids, triglycerides, and cholesterol esters of all the lipoproteid classes of the vascular wall and blood plasma. The fatty acid compostion of individual fractions proved to be similar in all the lipoproteid fractions. The lipids of the vascular wall not included into the lipoproteid composition differed considerably by their fatty acid composition from the lipids isolated from lipoproteids; lipids of the wall of the aorta contained much less unsaturated fatty acids than lipoproteids.     

Training affects muscle phospholipid fatty acid composition in humans.

Training improves insulin sensitivity, which in turn may affect performance by modulation of fuel availability. Insulin action, in turn, has been linked to specific patterns of muscle structural lipids in skeletal muscle. This study investigated whether regular exercise training exerts an effect on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P < 0.05). The ratio between n-6 and n-3 fatty acids was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P < 0.05). In contrast, training did not affect muscle triacylglycerol fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P < 0.05). In this model, diet plays a minimal role, as the influence of dietary intake is similar on both legs. Regular exercise training per se influences the phospholipid fatty acid composition of muscle membranes but has no effect on the composition of fatty acids stored in triacylglycerols within the muscle.     

Fatty acid composition of adipose tissue and blood in humans and its use as a biomarker of dietary intake

Accurate assessment of fat intake is essential to examine the relationships between diet and disease risk but the process of estimating individual intakes of fat quality by dietary assessment is difficult. Tissue and blood fatty acids, because they are mainly derived from the diet, have been used as biomarkers of dietary intake for a number of years. We review evidence from a wide variety of cross-sectional and intervention studies and summarise typical values for fatty acid composition in adipose tissue and blood lipids and changes that can be expected in response to varying dietary intake. Studies in which dietary intake was strictly controlled confirm that fatty acid biomarkers can complement dietary assessment methodologies and have the potential to be used more quantitatively. Factors affecting adipose tissue and blood lipid composition are discussed, such as the physical properties of triacylglycerol, total dietary fat intake and endogenous fatty acid synthesis. The relationship between plasma lipoprotein concentrations and total plasma fatty acid composition, and the use of fatty acid ratios as indices of enzyme activity are also addressed.     

Fatty acid values in the plasma of neonates, umbilical cord and maternal blood

The proportion of a wide range of fatty acids was studied in the plasma of 15 healthy newborn infants following a physiological pregnancy and delivery. The same measurements were done in seven healthy mothers (immediately after parturition) and the proportion of fatty acids was analysed in mixed umbilical cord blood (n = 7). The fatty acids were identified by gas chromatography as their methyl esters (FAME). In newborn infants the proportion of saturated fatty acids was found to be 42.3%, of monoene fatty acids 31.3% and of polyene fatty acids 25.4%; type n-6 fatty acids formed 13.9% and n-3 11.1%. The proportion of the various fatty acids in healthy maternal plasma was 37.9% (saturated), 34.4% (monoene) and 25.0% (polyene) respectively; type n-6 fatty acids formed 21.6% and type n-3 only 3.6%. The values in mixed cord blood were 44% (saturated FA), 34.8% (monoene FA) and 20% (polyene FA); group n-6 FA accounted for 17.4% and n-3 for only 2.1%. In the above three series we also described the sequence of the fatty acids present in the largest amounts. This is part of an extensive study, in a large series, of the commonest perinatal risks. We particularly draw attention to the high proportion of long-chain fatty acids (C 22 - C 26) in the plasma of healthy newborn infants.     

Fatty acid composition of lipids in erythrocytes and blood plasma in cadmium intoxication and its correction with unitiol

The effect of cadmium chloride on the fatty acid composition of lipids of the erythrocytes and blood plasma has been studied. It has been established that in the process of cadmium intoxication the decrease of the level of unsaturated fatty acids takes place and the most considerable changes in the content of oleic and arachidonic acids. It makes possible to assume the disturbance of both the erythrocytes membrane structure and metabolism in the erythrocyte. Unitiol injection promotes the normalisation of the indices under investigation.     

Fatty acid composition of the plasma lipids of newborn and maternal ruminants

1. The fatty acid compositions of the plasma lipids of newborn unsuckled lambs, kids, calves and piglets have been determined and compared with those of maternal plasma lipids at parturition. 2. The predominating plasma fatty acids in the newborn of all species are palmitic acid, C(16:1) acid, stearic acid and C(18:1) acid. This finding is consistent with the synthesis of the major proportion of fatty acids from non-lipid sources within the foetus. 3. Very small amounts of C(18:2) acid and C(18:3) acid are present in the plasma lipids of newborn ruminants, although considerable amounts of these fatty acids are contained in maternal plasma. The plasma fatty acids of the newborn piglet contained 5.5% of C(18:2) acid, those of the calf 2.0%, and those of the lamb and kid less than 1.0%. This finding is discussed in relation to the higher content of C(18:2) acid in the plasma non-esterified fatty acid fraction of the sow (15%) compared with that of the ruminant (less than 4%). 4. In the lamb and kid, but not in the calf or piglet, a C(20:3) acid was detected in plasma lipids that was very similar to, if not identical with, the C(20:3) acid that accumulates in the plasma of animals given diets low in essential fatty acids. The possible significance of this finding is discussed. 5. The cholesteryl esters of cow plasma were found to contain a higher percentage (43%) of C(18:3) acid than those of goat and sheep plasma (5-10%). The possible reasons for this difference are discussed.     

Microalgal fatty acid composition: rapid assessment using near-infrared spectroscopy

The feasibility of assessing microalgal fatty acid composition using near-infrared spectroscopy (NIRS) is described. The chlamydomonad microalga, Rhopalosolen saccatus (previously known as Characium saccatum), was isolated from the Fitzroy River, Central Queensland, Australia. R. saccatus was grown in batch culture with varying phosphorus nutrition and assessed for dry matter, total lipid and fatty acid composition using gas chromatography (GC). Transmission spectra (1100–2500 nm) were acquired of liquid culture, and reflectance spectra were acquired of wet and dry filtrates of cultures and of methyl esters. Partial least square (PLS) regression models were built on biomass, total lipid and a number of fatty acids. All sample presentation models supported PLS regression model with a cross validation correlation coefficient (R _cv) >0.87 for biomass and R _cv >0.68 for total lipid; however, the use of dry filtrates of culture is recommended as the sample presentation mode of choice. Models for fatty acids based on culture transmission spectra, reflectance spectra of wet and dry culture filtrates, or reflectance spectra of methyl esters in solvent were not acceptable. Dry extracts of methyl esters supported adequate models for fatty acids from C8:0 to C22:0, with the exception of capric and behenic acids, with an R _cv of 0.89–0.94; however, in practice, samples processed to this stage can be easily analyzed by GC. Near-infrared spectroscopy can be a potential choice for rapid estimation of biomass (dry matter) and lipid content and composition in microalgae, with further work required to demonstrate oping robustness of the calibration model in prediction of unknown samples.     

Fatty acid composition of whole bodies, specific tissues and cell lines of two lepidopteran insects

We detail the fatty acid compositions of last larval instars of two lepidopterans, Spodoptera frugiperda and Trichoplusia ni, two tissues from T. ni, a cell line derived from each species and the respective larval and cell culture media. Larval whole-body and specific tissue fatty acid profiles exhibited the major features commonly found in previous lepidopteran analyses, whereas the cell-line fatty acid compositions were substantially different from the compositions of both their growth media and larvae of their respective species. It appears that these cell-line patterns result from increased monoene biosynthesis in response to low levels of exogenous polyunsaturated fatty acids, a commonly observed essential fatty acid deficiency symptom in whole animals.     

Lactate concentration differences in plasma, whole blood, capillary finger blood and erythrocytes during submaximal graded exercise in humans

The aim of the study was to investigate the distribution of lactate in plasma, whole blood, erythrocytes, and capillary finger blood, before and during submaximal exercise. Ten healthy male subjects performed submaximal graded cycle ergometer exercise for 20-25 min. Venous blood samples and capillary finger blood samples were taken before exercise and every 5th min during exercise for lactate determination. The plasma lactate concentration was significantly higher (P less than 0.001, approximately 50%) than in the erythrocytes. This difference was not altered by the venous blood lactate concentration or exercise intensity. A significant difference (P less than 0.01) in lactate concentration was also found between capillary whole blood and venous whole blood. It was concluded that direct comparisons between lactate in capillary finger blood, venous whole blood and plasma could not be made.     

Fatty acid composition in native and cultured human endothelial cells

Summary Endothelial cells from human umbilical veins were isolated by collagenase treatment. Cells were cultured in the presence of either 20% fetal bovine serum (FBS) or 20% human serum (HS). At confluency, endothelial cell lipids were labeled with tracer concentrations of tritiated arachidonic acid, then extracted and separated into lipid subclasses by thin layer chromatography. The fatty acid composition of each lipid class was determined by glass capillary gas-liquid chromatography analysis and compared to that of cells freshly isolated from the cord (NC cells). The fatty acid compositions differed only in phospholipids. Polyunsaturated fatty acids (PFAs), arachidonic, and linoleic acids were depleted in FBS cell phospholipids and replaced by both stearic and oleic acids. No significant difference could be observed between NC cell and HS cell phospholipids. We conclude that PFAs might be decreased in FBS cells because of the relative paucity of PFAs in FBS as compared to HS. It seems therefore more convenient to cultivate endothelial cells in the presence of HS, especially in respect to their phospholipid content of arachidonic acid, which is the physiological reservoir for prostacyclin synthesis. This work was supported by a grant from the Délégation Générale à la Recherche Scientifique et Technique, Paris, France (79.7.0091).     

Fatty acid composition in native and cultured human endothelial cells

Endothelial cells from human umbilical veins were isolated by collagenase treatment. Cells were cultured in the presence of either 20% fetal bovine serum (FBS) or 20% human serum (HS). At confluency, endothelial cell lipids were labeled with tracer concentrations of tritiated arachidonic acid, then extracted and separated into lipid subclasses by thin layer chromatography. The fatty acid composition of each lipid class was determined by glass capillary gas-liquid chromatography analysis and compared to that of cells freshly isolated from the cord (NC cells). The fatty acid compositions differed only in phospholipids. Polyunsaturated fatty acids (PFAs), arachidonic, and linoleic acids were depleted in FBS cell phospholipids and replaced by both stearic and oleic acids. No significant difference could be observed between NC cell and HS cell phospholipids. We conclude that PFAs might be decreased in FBS cells because of the relative paucity of PFAs in FBS as compared to HS. It seems therefore more convenient to cultivate endothelial cells in the presence of HS, especially in respect to their phospholipid content of arachidonic acid, which is the physiological reservoir for prostacyclin synthesis.