Platelet Phospholipid Fatty Acids Research Articles

Research on the relationship between non-alcoholic fatty liver disease and platelet phospholipid fatty acids

Research on the relationship between non-alcoholic fatty liver disease and platelet phospholipid fatty acids

Erythrocyte and Platelet Phospholipid Fatty Acids as Markers of Advanced Non-Small Cell Lung Cancer: Comparison with Serum Levels of Sialic Acid, TPS and Cyfra 21-1

The phospholipid fatty acid profiles of erythrocytes and platelets from fifty patients with advanced non-small cell lung cancer were investigated using gas chromatography/mass spectrometry, followed by “ROC” curves analysis to gain novel biomarker information. Sialic acid and cytokeratins were also examined. Potentially useful fatty acid markers: Erythrocytes: phosphatidylcholine, 18:2n6 and 20:4n6; phosphatidylethanolamine, 22:4n6 and 22:6n3 + 24:1n9. Platelets: phosphatidylcholine, 22.0; phosphatidylethanolamine, 22:5n3 + 24:0. At the cut-off value to obtain maximum accuracy, the best biomarkers were found in platelets: phosphatidylserine + phosphatidylinositol (PS + PI), 21:0; sphyngomyelin: 20:1n9 and 22:1n9. All these fatty acids showed similar/higher diagnostic yields than the commonly used markers sialic acid or cytokeratins.

The effects of purified eicosapentaenoic and docosahexaenoic acids on arterial thrombosis tendency and platelet function in rats

Dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were compared for their effects on arterial thrombus formation in vivo using a well validated rat model. Platelet aggregation (triggered by collagen or adenosine diphosphate in whole hirudinized blood), thromboxane formation (TxB 2) and platelet phospholipid fatty acid composition were measured also. Animals fed diets containing hydrogenated coconut oil or sunflower seed oil served as prothrombotic and antithrombotic controls, respectively. In a first study, rats were fed a mixture of EPA and DHA ethyl esters (MIX) in increasing amounts and results indicated that 4% of n−3 fatty acids had an optimum reducing effect on thrombosis tendency. Dietary administration of MIX further resulted in a dose-dependent promotion of disaggregation after collagen-induced aggregation, which significantly correlated with the reduction in platelet TxB 2 formation. In a subsequent comparative study, both EPA and DHA ethyl esters affected thrombosis tendency, platelet aggregation and TxB 2 formation to a similar extent. In addition, both polyenes increased the apparent thromboxane A 2-sensitivity of platelets, which appeared negatively related to arterial thrombosis tendency. We conclude that EPA and DHA have similar reducing effects on arterial thrombogenesis in vivo in rats and have comparable effects on the selected platelet functions in vitro.

Relationship between plasma and platelet phospholipid fatty acid composition in healthy subjects

In order to furtherly clarify the mechanisms regulating the fatty acid composition of platelet phospholipids the relationships between the fatty acid composition of major phospholipid fractions from plasma and platelets were investigated in 30 healthy male subjects. Strict correlations between all but two plasma and platelet fatty acids were observed for phosphatidylcholine (PC) (r = 0.51-0.95, at least P < 0.01), whereas only poor correlations were found for the other fractions. These results suggest that the direct transfer of PC molecules from plasma to platelet membrane is a pivotal mechanism for renovation of platelet PC fatty acids, while other mechanisms appear to play a major role for renovation of other phospholipid fractions of the platelet membrane.

Palmolein and groundnut oil have comparable effects on blood lipids and platelet aggregation in healthy Indian subjects

Substitution of palmolein (POL) for groundnut oil (GNO) doubles saturated fatty acids and decreases by half the linoleic acid (18:2n-6) content of Indian diets. The effects of this substitution on selected parameters of cardiovascular risk and membrane functions were studied in middle-aged subjects. Both metabolic (short-term) and "in-home" (long-term) studies were conducted, and the subjects were crossed over from GNO to POL or vice versa. During both studies and in both sexes, blood pressure, plasma levels of total cholesterol and triglycerides and their distributions in various lipoprotein fractions were not altered. The lower 18:2n-6 and higher 16:0 intakes were reflected in fatty acid compositions of cholesteryl esters and triglycerides. However, the plasma and platelet phospholipid fatty acid patterns did not shift toward saturation. The observation that the levels of long-chain polyunsaturated fatty acids in phospholipids were similar at the end of GNO and POL regimens indicates that 18:2n-6 furnished during POL regimen may be sufficient to maintain the levels of arachidonic acid in cell membranes. Platelet aggregation, erythrocyte membrane fluidity, and activity of Na+, K+ ATPase, a membrane-bound enzyme, were essentially similar at the end of the two oil regimens. These results indicate that POL is comparable to GNO and may not induce hypercholesterolemia in Indian subjects consuming cereal-based diets containing 30% total fat calories and low cholesterol.

Alpha-Linolenic acid- and docosahexaenoic acid-enriched eggs from hens fed flaxseed: influence on blood lipids and platelet phospholipid fatty acids in humans

This study was undertaken to examine the effects that consumption of eggs from hens fed diets containing flaxseed would have on plasma and platelet lipids of male volunteers. Feeding diets containing 0%, 10%, and 20% ground flaxseed to Leghorn pullets provided a marked progressive increase in n-3 fatty acid content as alpha-linolenic acid (alpha-LNA) (28, 261, and 527 mg/egg) and docosahexaenoic acid (DHA) (51, 81, and 87 mg/egg) but no alteration in the cholesterol concentration of the egg yolk. Twenty-eight male volunteers, divided into three groups, were fed four eggs per day for 2 wk according to a cyclic Latin-square design. No statistically significant changes were observed in total cholesterol, high-density-lipoprotein cholesterol, or plasma triglyceride concentrations. Significant increases in total n-3 fatty acids and in DHA content (which rose from 1.5 to 2.0% by wt or 33% overall), and a significant decrease in ratio of n-6 to n-3 fatty acids were found in platelet phospholipids of subjects consuming eggs from flaxseed-fed hens. Health and Welfare Canada in 1990 set recommended intakes for dietary n-3 fatty acids and for the ratio of n-6 to n-3 fatty acids, which are not being met currently by the overall population. Eggs modified by the inclusion of flaxseed in the laying hens' diet could provide an important nutritional source of n-3 fatty acid.

Effects on blood pressure of omega 3 fats in subjects at increased risk of cardiovascular disease.

This study was conducted to compare the effects of omega 3 fatty acids, taken as fish or fish-oil supplements in the setting of a high- or low-fat dietary background, on blood pressure and heart rate in men with moderate cardiovascular risks. One hundred twenty men were randomly allocated to five high-fat (40% of daily energy) and two low-fat (30% of energy) groups to undertaken a 12-week dietary intervention period involving fish, fish oil, or a combination of these. Sodium intake was restricted to less than 90 mmol/d. The five high-fat groups were assigned to take either 6 or 12 fish-oil capsules daily, fish or a combination of fish oil and fish, or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals were devised to provide 1.3 g of eicosapentaenoic acid daily, equivalent to that contained in 6 fish-oil capsules. Subjects were instructed to eat a selection of fish that provided an average of 3.65 g/d (range, 3.2 to 4.1 g/d) of total omega 3 fatty acids. Subjects were seen at regular intervals during the baseline and dietary intervention periods for measurement of weight, blood pressure, heart rate, dietary compliance, urinary electrolyte excretion, platelet phospholipid fatty acids, blood glucose, and insulin concentration. There was a greater fall in both systolic and diastolic blood pressures in subjects allocated fish or fish oil, particularly in the low-fat groups, compared with control subjects. However, there was no significant group effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the effects of diets rich in stearic acid versus myristic acid and lauric acid on platelet fatty acids and excretion of thromboxane A 2 and PGI 2 metabolites in healthy young men

The present study compared the effects of diets rich in stearic acid (C18:0) versus one high in lauric and myristic acid (C12:0, C14:0) on platelet phospholipid fatty acid levels and concentrations of urinary thromboxane B 2 (TXB 2) and 6-keto-PGF 1α, which are stable metabolites of thromboxane A 2 (TXA 2) and PGI 2 and indicators of cardiovascular hemostasis. A diet high in dairy butter (B) was the source of C12:0 and C14:0; C18:0 was provided by diets high in cocoa butter (CB), milk chocolate (CHOC) or CB + B in a 4:1 ratio (MIX). A randomized, crossover double-blind experimental design was used. Experimental subjects (n = 15) consumed each diet for 26 days, with a 1-month washout period between each experimental period. Urine and blood were collected from each subject at the beginning and end of each dietary period. Urinary TXB 2 and 6-keto-PGF 1α were analyzed by radioimmunoassay (RIA). There were no effects of diet on the 24-hour excretion of either metabolite or on the ratio of 6-keto-PGF 1α TXB 2 , even though there were significant changes in the eicosanoid precursor, arachidonic acid (C20:4n-6), in platelet phospholipids. C20:4n-6 levels increased (44.8% ± 1.0% to 47.1% ± 1.3%; P < .05) in the phosphatidylethanolamine phospholipid subclass in subjects on the B diet and decreased in the phosphatidylcholine subclass on the CB diet (16.5% ± 1.0% to 14.2% ± 1.1%; P < .05) compared with baseline values. Although there were modest effects of diets high in C12:0 and C14:0 versus C18:0 on the fatty acid precursor of TXA 2 in platelet phospholipids, these were not associated with any differences in urinary eicosanoid excretion. Thus, our results demonstrate that diets high in these respective fatty acids do not affect hemostasis compared with baseline values, as measured by eicosanoid excretion.

Modifications of platelet phospholipid fatty acid composition in streptozocin-induced diabetic rats

Increased thromboxane A 2 (TXA 2) generation by platelets has been reported both in diabetic patients and streptozocin-induced diabetic rats. This increase is in contrast to the decreased prostacyclin (PGI 2) synthesis by endothelial cells in diabetes. An imbalance in the ratio of TXA 2/PGI 2 has been implicated in increased platelet aggregation and a high incidence of vascular disease in human diabetes. The mechanism for this imbalance, however, remains elusive. In a previous study from our laboratory, we reported unchanged arachidonic acid levels in platelet membrane phospholipids of 3-week diabetic rats, but a decreased arachidonic acid level in platelet membrane phospholipids of 6-week diabetic rats. In the present communication, we report the role of enzymes that are involved in remodeling arachidonic acid levels of platelet membrane phospholipids in both 3- and 6-week diabetic rats. No alterations were observed in the activities of arachidonoyl-CoA synthetase, acyl-CoA: lysophosphatidylcholine acyltransferase, or phospholipase A 2 in platelets from both 3- and 6-week diabetic rats. However, both increased uptake and incorporation of [ 14C]arachidonic acid into platelets were observed in the diabetic platelet-rich plasma. In conclusion, increased TXA 2 formation in diabetic platelets is not due to alterations in the activities of enzymes involved in the incorporation into or release of arachidonate from the diabetic platelet membrane phospholipid, but may be due to increased efficiency of uptake, incorporation or possibly redistribution of this fatty acid among phospholipid classes in diabetic platelets.

Parenteral nutrition using MCT/LCT or LCT: Effect on the fatty acid composition of plasma triglycerides and platelet phospholipids

Plasma triglyceride fatty acids and platelet phospholipid fatty acids were compared in 20 malnourished patients before and after 8–10 days of total parenteral nutrition which included either a conventional lipid emulsion (LCT) or a new emulsion containing medium chain triglyercides (MCT/LCT). The use of both lipid emulsions altered the fatty acid profiles. The percentage of linoleic acid in the plasma triglycerides increased with both lipid emulsions, but more markedly with LCT. The median percentage after LCT was 25.9 (range 16.9–31.5) which was significantly higher (p < 0.01) than after MCT/LCT — 14.8 (range 6.1–20.2), or in healthy volunteers. After 8–10 days on MCT/LCT the fatty acid profile retained some features of the malnourished state, despite correction of the linoleic acid content. The percentage of linolenic and arachidonic acid in the platelet phospholipids tended to be lower than after LCT use, and the percentage of linoleic acid was significantly less (p < 0.01), the median (range) being 8.2 (4.5–23.8) after MCT/LCT and 11.7 (4.8–16.0) on LCT. Short term use of MCT/LCT emulsion may correct the fatty acid changes of malnutrition rather more slowly and results in a different fatty acid profile to that seen after LCT use. Whether this has any clinical effects is unclear.

Effect of catfish and salmon diet on platelet phospholipid and blood clotting in healthy men

The effect of diets containing either catfish or salmon fish on blood clotting and platelet phospholipid fatty acid composition was studied in 17 healthy, young men. The subjects received a control diet for 21 days followed by either catfish diets ( n = 9) or salmon diets ( n = 8) for an additional 19 days. Catfish and salmon diets prolonged the subjects' bleeding times (by 66% and 57%, respectively) and clotting times (by 25% and 31%, respectively), P < 0.05. The platelet count in catfish and salmon groups decreased by 7% and 9%, respectively. There were no differences in the prothrombin time (PT) and activated partial thromboplastin time (APTT). A small but significant increase ( P < 0.05) in fibrinogen concentration was observed in catfish (243.7 mg/dL) and salmon diet groups (246.5 mg/dL) compared to the control group (223.9 mg/dL). Diets containing catfish and salmon led to significant incorporation of total n-3 polyunsaturated fatty acids, PUFAs (from 5.04% on the control to 6.14% and 10.26%, respectively) and total EPA + DHA (from 3.77% on the control to 4.84% and 8.83%, respectively). The n-3/ n-6 ratio increased in both groups while the ratio of 20:5/20:4 increased only in the salmon group from 0.05 on the control diet to 0.14. The reduction in arachidonic acid (20:4 n-6) and total n-6 PUFAs was not statistically significant in the catfish group but was significant in the salmon group. The findings suggest that there were minor differences between hemostatic parameters in men fed catfish and salmon. The consumption of either diet led to incorporation of dietary n-3 PUFAs into platelet phospholipids, and may result in alteration in platelet and hemostatic function in men.

Platelet fatty acids and function in two distinct regions of Belgium: relationship to age and dietary habits

We compared the dietary habits, fatty acid composition of plasma and platelet phospholipids, and platelet function in two groups of healthy Belgian male subjects, known to differ in their mortality rate from coronary heart disease (CHD). In the Walloon subjects, there was a larger intake of saturated and a lower intake of (n-6) polyunsaturated fats, confirmed by the fatty acid composition of plasma and platelet phospholipids. While plasma HDL and total cholesterol were similar in the present samples of the two communities, platelet aggregation to epinephrine was significantly higher in the Walloon subjects. When the two populations were divided into younger (28-54 years) and older (55-73 years) age groups, the older Walloon subjects exhibited platelet hyper-aggregability to most of the agonists, compared to the other three groups. In addition to dietary fats, alcohol and smoking habits, age was an important determinant of platelet phospholipid fatty acids and platelet reactivity. The present results reinforce those of previous studies, indicating that platelet behaviour is significantly affected by the main risk factors for CHD.

Sex related differences in platelet TXA 2 generation

Platelet lipid composition, 1–14C arachidonic acid (AA) metabolism by platelets (stimulated with thrombin), serum thromboxane (Tx)B 2 production and plasma lipid composition were investigated in 53 healthy females (18–45 years) and 65 males (19–45 years) with similar dietary habits. In males, serum TxB 2 production and cholesterol platelet membrane levels were found significantly higher (p<0.001 and p<0.05) than in females. No differences were observed between the two groups in the AA conversion through cyclo-oxygenase and lipoxygenase pathways or in the platelet phospholipid fatty acid composition. These findings indicate that in males the platelet proaggregatory capacity is greater than in females and the higher platelet TxB 2 production does not depend on a larger AA availability or on enzyme activation for its conversion. The increased TxB 2 production may be, at least in part, induced by functional differences such as a different membrane cholesterol content inducing, in its turn, an increased microviscosity and/or higher number of platelet receptors for thrombin.

Platelet fatty acid composition in relation to fatty acid composition in plasma and to serum lipoprotein lipids in healthy subjects with special reference to the linoleic acid pathway.

The fatty acid composition in platelet phospholipids and in the plasma lipid esters as well as the serum lipoprotein lipid concentrations were determined in 67 healthy male subjects in order to establish the relationships between blood lipids and platelets. A positive correlation was found between the concentrations of the triglyceride rich serum lipoprotein lipids and the relative percentage of saturated and monounsaturated fatty acids in plasma. The correlations were also positive between the serum high density lipoprotein-cholesterol concentration and the relative content of linoleic acid in the plasma cholesterol esters and phospholipids. Negative correlations were found between the relative percentage of saturated and monounsaturated fatty acids in the plasma lipid esters versus linoleic acid in plasma and in the platelets. On the other hand there were positive correlations between linoleic acid in the plasma lipid esters and in the platelet phospholipids. These results indicate a direct dietary influence on the platelet phospholipid fatty acid composition. The correlations between the fatty acids of the n-6 series within plasma and platelets as well as between plasma and platelets indicate that a high linoleic acid content is not associated with an increased arachidonic acid concentration. The results also indicate that the limiting metabolic step in the conversion of linoleic acid into arachidonic acid may be located at different levels in plasma and in the platelets.

“Ex Vivo” Influence of Fatty Acids from Plasma Cholesterol and Triglycerides on the Fatty Acid Pattern of Platelets

We have studied "ex vivo", in 92 normal subjects, the influence of fatty acids (FA) that esterify plasma cholesterol and triglycerides on the fatty acid composition of phospholipids, triglycerides and free fatty acid fractions in platelets. High and significant correlations (p less than 0.001) were found for some of the platelet phospholipid FA and the same FA that esterify plasma cholesterol [18:1 (r = 0.56); 18:2 (r = 0.71) and 20:5 (r = 0.42)] and plasma triglycerides [18:1 (r = 0.57) and 18:2 (r = 0.66)]. Some significant correlations were also found between some of the platelet triglyceride FA and the same FA that esterify plasma phospholipids [18:1 (r = 0.58)], triglycerides [18:1 (r = 0.51), 18:2 (r = 0.52)] cholesterol [18:1 (r = 0.44)] and plasma free fatty acids [18:1 (r = 0.39); 18:2 (r = 0.40)]. By evaluating these results in conjunction with those of an earlier study, it can be concluded that "in vivo" the FA from different plasma lipid fractions and especially those esterifying the plasma cholesterol and phospholipid fractions, can influence the FA composition of platelet phospholipids in normal subjects. In trying to interpret the role played by plasma lipids in platelet lipids, it may be of interest to take into account the interrelationships found in this study.

Platelet membrane fluidity and aggregation of rabbit platelets

Aggregation of rabbit platelets from citrated plasma in response to ADP was directly correlated with platelet plasma membrane fluidity as determined by fluorescence depolarization measurements with the probe diphenylhexatriene. Rabbits were maintained for periods of 200 and 400 days on potentially hyperlipidemic diets (20% fat by weight) with varying levels of saturated and polyunsaturated fatty acids. Dietary variations were effective in modulating the mole percentage distribution patterns of the platelet phospholipid fatty acids. The major chemical control of membrane fluidity was the actual mass of unsaturated lipid in the cells and not simply the relative percentage distributions of such unsaturated fatty acids. Substantially higher phospholipid/protein ratios were observed upon analysis of platelets and platelet membranes from rabbits after 200- than after 400-day diet periods. Accordingly lipid structures were significantly more fluid in either whole platelets or membrane isolates at the end of the shorter diet period. The observations pertaining to the extent of aggregation and membrane fluidity are in consonance with the general role of membrane fluidity in controlling biological activity and support the concept that platelet aggregation is a membrane-associated phenomenon.

Influence of Some Plasma Fatty Acids on the Phospholipid Fatty Acid Pattern of Human Platelets – An “Ex Vivo” Experience

Some correlations between plasma and platelet fatty acids (FA) were evaluated "ex vivo" in 94 normal subjects. The highest relationships between total FA from plasma and platelets were found for 18:1 (r = 0.74) and 18:2 (r = 0.67). Low correlations were obtained for free fatty acids (FFA). The most significant correlations between fatty acids esterifying plasma and platelet phospholipids were found for the 18:1 (r = 0.66); 18:2 (r = 0.74) and 20:5 (r = 0.66). Our results suggest that the platelet phospholipid FA could be more easily modified by plasma variation in the FA composition of phospholipids than by variations in the plasma FA composition of the FFA fraction. In addition, the incorporation of FA from plasma into the platelet phospholipids "in vivo" may take place through an acylation-deacylation process and also by the incorporation of whole plasma phospholipid molecules into the platelets, probably through an exchange of plasma lipoproteins and platelets. Finally, arachidonic acid seems to have a different and selective way of incorporation into platelet phospholipids.

EFFECTS OF 11-WEEK INCREASE IN DIETARY EICOSAPENTAENOIC ACID ON BLEEDING TIME, LIPIDS, AND PLATELET AGGREGATION

The effect of a diet rich in eicosapentaenoic acid (EPA) on platelet phospholipid fatty acid composition, platelet aggregation, and bleeding time was studied in 10 healthy men, whose usual diet was partly replaced by fish for 11 weeks. This diet provided 2-3 g EPA per day. Two doses (3. 5 and 10 mg/kg body-weight) of acetylsalicylic acid (ASA) were given before and during the diet. The fish diet prolonged bleeding time (by 42%) and decreased platelet aggregability. The changes in platelet phospholipid fatty acid composition consisted of increases in the ω-3 series (C20:5 and C22:6) and decreases in the ω-6 series (C18:2 and C20:3). The reduction in platelet aggregation induced by collagen and ADP did not parallel the changes in platelet membrane phospholipids and bleeding times. Diminished platelet aggregation induced by collagen lasted only 3 weeks (while subject was still on the diet), whereas the decreased sensitivity to ADP persisted for at least 11 weeks after the volunteers had resumed their normal diet. ASA taken before the diet prolonged bleeding time by as much as did the diet itself. ASA taken during the diet prolonged bleeding time by more than the sum of the increases in bleeding time caused by ASA and by the EPA diet separately, but the synergism was not significantly more than additive. The findings suggest that a diet rich in ω-3 polyunsatured fatty acids reduces the interaction between platelets and the vessel wall by mechanisms which are more complex than just a reduction in susceptibility of platelets to the naturally occurring agents collagen and ADP, or an imbalance between proaggregatory and anti-aggregatory prostaglandin derivatives.

Rat Platelet Prostaglandin, Cyclic AMP and Lipid Response to Variations in Dietary Fat

Diets supplying 20 or 40% of the calories as fat with linoleate to saturated fatty acid ratios of 0.4, 0.8 and 5.5 were fed to male weanling rats for 8 and 11 weeks. Recalcification clotting time was not affected by dietary treatment. Concentration of cAMP in the platelets was significantly elevated at the highest level of dietary linoleate. Cyclic AMP was negatively correlated with concentration of dihomo-γ-linolenic acid in platelet phospholipids and positively correlated with prostaglandin E1, suggesting that dihomo-γ-linolenic acid is rapidly converted to prostaglandin E1 causing a rise of cAMP due to stimulation of adenylate cyclase. Dietary treatment did not markedly change the composition of the platelet phospholipid fatty acids and, therefore, resulted in no change in synthesis of the proaggregatory prostaglandin by platelets during clotting. Although the fatty acid composition of the platelet phospholipids remained constant, dietary treatment did affect the total amount of phospholipid fatty acid present in the platelet. Serum concentrations of cholesterol were significantly higher in rats fed the 20% fat diet than in rats fed the 40% fat diet. Platelet cholesterol followed the same trend as serum cholesterol indicating that the cholesterol content of platelets appears to reflect the lipid environment of the plasma.platelet prostaglandin fat cholesterol phospholipid

Effect of dietary linoleic acid on platelet function in the rat.

<h2>Abstract</h2> The effect of different concentrations of dietary linoleic acid (from 0 to 6 %) in the form of corn oil, at the expense of hydrogenated coconut oil (HCO) (saturated fat) on platelet functions, was studied in male rats fed purified diets. Increased amounts of linoleic acid were associated with decreased susceptibility of platelets to thrombin-induced aggregation and prolongation of the platelet-rich plasma clotting time. Platelet functions of rats fed HCO (38 %) were also compared to those of rats fed diets lower (24–28%) in HCO, but high in either linoleic acid, oleic acid or glucose. Solely the group fed high amounts of linoleic acid presented a lower platelet aggregation than the group fed 38 % HCO. An increase in 18:1, 20:3ω9 and in the ratio 20:4/18:2 seems to be, in both studies, in the platelet phospholipid fatty acids, the change the most closely associated with the platelet enhanced activities. In rat, dietary linoleic acid is apparently responsible for a specific protective effect on platelet functions which cannot be observed by merely decreasing the level of saturated fat.