Proportion Of Arachidonic Acid Research Articles

α-Linolenic, Eicosapentaenoic and Docosahexaenoic Acids Affect Lipid Metabolism Differently in Rats

Rats were fed purified diets containing 10% fat with constant (n-6):(n-3) polyunsaturated fatty acids [(n-6):(n-3); 2.3-2.6] and polyunsaturated:saturated fatty acids (1) ratios. This was obtained with alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid added at 1 g/100 g diet. Eicosapentaenoic acid and docosahexaenoic acid were added as the ethyl esters. The concentration of plasma cholesterol in rats fed docosahexaenoic acid was significantly lower than in those fed alpha-linolenic acid. The concentration of plasma triglyceride was significantly lower in rats fed eicosapentaenoic acid than in those fed docosahexaenoic acid. Docosahexaenoic acid significantly reduced hepatic cholesterol compared with alpha-linolenic acid and eicosapentaenoic acid. Both eicosapentaenoic acid and docosahexaenoic acid decreased hepatic triglyceride compared with alpha-linolenic acid, but this effect was more pronounced in the docosahexaenoic acid group. There was no significant difference in fecal excretion of neutral and acidic steroids and apparent fat absorption. In rats fed docosahexaenoic acid, the proportion of arachidonic acid in liver microsomal phosphatidylcholine was lower than in those fed eicosapentaenoic acid. The same tendency was observed in plasma, platelet and aortic phosphatidylcholine and liver microsomal phosphatidylethanolamine and phosphatidylinositol. Dietary docosahexaenoic acid, but not eicosapentaenoic acid, significantly decreased aortic production of prostacyclin compared to alpha-linolenic acid, whereas platelet aggregation by collagen was not affected by the difference in dietary (n-3) polyunsaturated fatty acids.

Differential Changes in Relative Levels of Arachidonic Acid in Major Phospholipids from Rat Tissues during the Progression of Diabetes1

Changes in the fatty acid composition of choline glycerophospholipid (CGP) and ethanolamine glycerophospholipid (EGP) in the liver, heart, kidney, testis, spleen, and brain of rats were examined at various stages of streptozotocin-induced diabetes. Diabetes of prolonged duration (8 weeks) caused profound alterations in the fatty acid composition of phospholipids in these tissues, the most consistent of which were a decrease in the relative level of arachidonic acid and an increase in that of linoleic acid. Although a decrease in the relative proportion of arachidonic acid in CGP was a common feature seen in all tissues after long-term diabetes, the profile of the reduction during the progress of diabetes differed among the tissues. A rapid decrease was found in the liver and plasma at an early stage of diabetes (7 days), while the reductions level of arachidonic acid in CGP of the heart, kidney, and testis appeared at a later stage of diabetes (3 weeks). CGP from the brain retained the normal amount of arachidonic acid over the first 4 weeks of diabetes and no consistent changes in the fatty acid composition of phospholipids were found during this time. A slight change in the level of arachidonic acid composition in CGP from the brain was found after 8 weeks of diabetes. The present study indicates that the extent of reduction in the levels of arachidonic acid of CGP in the tissues examined was dependent on the duration of diabetes in every case.

The effect of oral administration of eicosapentaenoic and docosahexaenoic acids on acute inflammation and fatty acid composition in rats.

To investigate effects of eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) on acute inflammation, we fed rats either of the following four diets: an EPA-rich diet for 5 or 15 days, a DHA-rich diet for 5 or 15 days, a control diet for 5 or 15 days, and standard chow for 15 days. At the end of diets, the carrageenan-induced swelling of footpads was measured. Peritoneal cells were analyzed for their fatty acids in the phospholipid fraction. The swelling was similarly reduced in the EPA and DHA groups (p < 0.05, if fed for 15 days) compared with rats fed the control diet for 15 days. The mean proportion of arachidonic acid (AA) to the sum of highly unsaturated fatty acids was correlated (r = 0.87) to the mean degree of swelling among all dietary groups (n = 7). Effects of EPA and DHA might be explained by the reduced availability of AA for eicosanoid formation represented by the proportion of AA.

Essential polyunsaturated fatty acids from 14 species of diatom (Bacillariophyceae)

The lipid class and total fatty acid compositions of 14 species of diatom (class Bacillariophyceae) were examined. The major lipid class in these microalgae was polar lipid (50.1-90.8%), although in some species, triacylglycerols (0.3-47.7%) and free fatty acids (0-29.2%) were also abundant in the logarithmic phase cultures. The major fatty acids in most species were 14:0, 16:0, 16:1 ( n-7) and 20:5( n-3). The polyunsaturated fatty acids 16:2( n-4), 16:3( n-4), 16:4( n-1), 18:4( n-3) and 22:6( n-3) also comprised a significant proportion (>4% each) of the total fatty acids in some species. The characteristic fatty acid composition of diatoms is readily distinguishable from those of other classes of microalgae. The mean proportion of 22:6( n-3) was significantly higher in representatives from the order Centrales (4.9%) than the Pennales (1.6%), but there was no consistent difference in the proportions of the other fatty acids. Four of the pennate diatoms contained significant proportions of arachidonic acid, 20:4( n-6) (3.5-5.6%), but most species examined contained very low proportions of ( n-6) polyunsaturated fatty acids. Based on the lipid compositions, all of the diatom species studied are potentially suitable sources of some of the longer chain polyunsaturated fatty acids.

Alterations by clofibric acid of glycerolipid metabolism in rat-kidney

Alterations induced by p-chlorophenoxyisobutyric acid (clofibric acid) in glycerolipid metabolism in rat-kidney were studied. (1) The treatment of rats with clofibric acid markedly decreased renal level of triacylglycerol, which seemed to be due to a reduced formation of triacylglycerol, since the in vivo incorporation of [ 14C]oleic acid (18:1), [ 14C]linoleic acid (18:2) and [ 3H]glycerol into triacylglycerol was decreased in clofibric acid-fed rats. (2) The administration of clofibric acid to rats increased proportions of 18:1 and 18:2 and decreased a proportion of arachidonic acid (20:4) in phosphatidylcholine; the contents of two major molecular species of renal diacylglycerophosphocholine (diacyl-GPC), palmitoyl-arachidonoyl (16:0–20:4) and stearoyl-arachidonoyl (18:0–20:4), were both decreased markedly. The treatment did not alter renal content of phosphatidylcholine. (3) By contrast, clofibric acid changed, to a lesser extent, the composition of molecular species of diacylphosphatidylethanolamine. (4) The decrease in the level of diacyl-GPC that contains 20:4 seemed to be due to the clofibric acid-caused reduction in the concentration of free 20:4 in kidney. The reduction in renal concentration of free 20:4 seemed to be caused by a decrease in serum concentration of lipids that contain 20:4, but not by a decrease in the activities of desaturation and chain elongation that participate in biosynthesis of 20:4. (5) The reduction by clofibric acid in the renal content of diacyl-GPC containing 20:4 resulted in the decrease in the formation of prostaglandin E 2 in kidney.

Influence of cyclopropene fatty acids (Baobab seed oil) feeding on the in vitro Δ9 desaturation of stearic acid in rat liver microsomes

Δ9 desaturation of [1− 14 C] stearic acid to oleic acid was studied in liver microsomes of rats fed either fresh Baobab seed oil, containing cyclopropene fatty acids (malvalic acid and sterculic acids), or heated Baobab oil, containing only minor amounts of these acids. This was compared with rats fed a control oil mixture or a fat-free diet. Up to 50 nmol of substrate, Δ9 desaturation rate was the same in rats fed the three fat diets. From 50 to 150 nmol, the desaturation rates were practically constant in rats fed fresh Baobab seed oil. It increased in heated oil-fed rats at the same rate as in the control group, but more slowly than in the fat-free diet group. Fatty acid composition of liver microsomal lipids did not reflect the in vitro observed desanturation rate because monounsaturated fatty acids were in the same percentages in fresh and heated Baobab seed oil-fed rats. Moreover, the proportion of arachidonic acid was lower, and that of linoleic acid higher for both diets, in comparison with controls, suggesting a decreased Δ6 and/or Δ5 desaturation rate.

The Colostrum-Deprived Piglet as a Model for Study of Infant Lipid Nutrition

The large proportions of arachidonic acid (20:4 omega-6) and docosahexaenoic acid (22:6 omega-3) in brain and retina structural lipids are important for normal central nervous system function. Study of dietary requirements for omega-6 and omega-3 fatty acids for brain growth is difficult in the human infant because of variabilities in human milk fatty acids, lack of correspondence between blood lipids and central nervous system (CNS) lipids and ethical limits of tissue analyses. Comparison of nutrient requirements, lipid digestion, absorption and transport and milk and brain lipids and the timing of intestinal maturation and the brain growth spurt during fetal-infant development show the piglet to be an excellent choice for studies relevant to lipid nutrition of term gestation infants. Of practical relevance, piglets are easily hand-fed and, with a relatively large body size and rapid growth, provide ample tissue for analyses of the effects of diet fat on specific CNS cell membranes. Use of the piglet to define omega-6 and omega-3 fatty acid requirements and the effects of addition of marine oils to formulas and the lactating mother's diet on the developing CNS are described.

Combined effects of dietary protein and fat on lipid metabolism in rats.

The combined effects of dietary protein (casein, whey protein, or soy protein) and fat (safflower oil, perilla seed oil, or their mixed oil; linoleic acid/alpha-linolenic acid = 5.0) on several lipid parameters were studied in rats. Serum cholesterol and triglyceride levels were lower in perilla seed oil groups irrespective of the protein sources. Liver triglyceride level, and fecal excretion of steroids were influenced mainly by protein sources, particularly isolated soy protein lowered liver triglyceride level, and increased the fecal steroid excretion. The fatty acid composition of liver phosphatidylcholine was influenced by dietary fat sources. The proportion of arachidonic acid was significantly lower in rats fed perilla seed oil than in those fed safflower oil or mixed oil, while the proportion of eicosapentaenoic acid was higher in rats fed perilla seed oil than in those fed safflower oil. Arachidonic acid/linoleic acid ratio was significantly lower in perilla seed oil groups, and tended to be higher in casein groups. Eicosapentaenoic acid/arachidonic acid ratio was influenced by both dietary protein and fat, and protein-fat interaction was observed. Eicosapentaenoic acid/arachidonic acid ratio was higher in perilla seed oil groups, and isolated soy protein in perilla seed oil groups lowered the ratio in comparison with other protein sources in perilla seed oil groups.

Effects of Different Triglyceride Saturated Fatty Acids on Tissue Lipid Level, Fatty Acid Composition, Fecal Steroid Excretion, Prostacyclin Production, and Platelet Aggregation in Rats.

Male Sprague-Dawley rats were fed for 3 weeks cholesterol-enriched diets containing 7% interesterified fats in which saturated fatty acids, lauric, myristic, palmitic, and stearic acids, were the sole variable. The dietary fat was composed of 50% saturated fatty acid, 30% oleic acid, 14% linoleic acid, and 6% α-Iinolenic acid (P/S =0.4, n-6/n-3 =2.3). There was no difference in food intake, body weight gain, or liver and epididymal adipose tissue weight among the groups, although the apparent fatty acid absorption decreased with increasing chain-length of dietary saturated fatty acids. Plasma lipid levels were comparable among the groups, but the concentration of liver cholesterol was significantly lower, and fecal excretion of neutral but not acidic steroids was significantly higher in the stearic acid group even compared with the palmitic acid group. The liver triglyceride decreased upon feeding palmitic or stearic acid fats. The fatty acid composition of adipose tissue but not liver triglyceride apparently reflected the source of dietary fats, but a considerable portion of stearic acid appeared to be desaturated to oleic acid. The proportion of arachidonic acid in plasma cholesterol ester and that of linoleic acid in liver phosphatidylethanolamine decreased with the chain-length of saturated fatty acids. The stearic acid-fat significantly reduced platelet aggegation by ADP and aortic production of prostacyclin, and there was a similar but to a less marked response pattern in the palmitic acid-fat. These observations suggest that the different saturated fatty acids exert differential effects on various lipid parameters.

Effect of intravenous polyunsaturated phosphatidylcholine infusion on insulin receptor processing and lipid composition of erythrocytes in patients with liver cirrhosis.

The aim of this study was to determine whether insulin receptor processing capabilities of human erythrocytes could be improved by changing the cell membrane lipid composition using an intravenous infusion of polyunsaturated phosphatidylcholine. Thirteen cirrhotics were submitted to the i.v. infusion of phosphatidylcholine (2 g day-1 for 3 days). Both erythrocyte lipid composition and insulin receptor processing ability were examined at the beginning of the study and at 0, 3 and 11 days after the end of the treatment. This treatment decreased the erythrocyte cholesterol to phospholipid molar ratio and increased the proportion of polyunsaturated fatty acids (mainly linoleic acid) immediately after the end of the treatment. The proportion of arachidonic acid increased immediately in the phosphatidylserine class and, a few days later, also in phosphatidylethanolamine. The phospholipid class distribution did not show any relevant modification in the course of the study. Surface insulin receptors, which generally were up-regulated in the untreated subject (-7.1 +/- 20.4%), showed an improvement in down regulation capabilities that appeared to be well correlated with the changes in lipid composition of cell membranes induced by i.v. infusion of polyunsaturated phosphatidylcholine. The confirmation of these findings also in target cells for insulin may open new perspectives in the treatment of diabetes mellitus.

The effect of different dietary lipid supplements on the nonesterified fatty acid composition of normoxic rat hearts: A link between nutrition and cardiac arrhythmia

In addition to changes in the fatty acid composition of cardiac membrane phospholipids, alterations in the dietary lipid intake of rats influence the composition but not the amount of myocardial nonesterified fatty acids (NEFA's). These changes are apparent in the relative proportions of arachidonic acid (AA) and those other polyunsaturated fatty acids (PUFA's) such as linoleic acid (LA) or docosahexaenoic acid (DHA) which are either substrates for or competitive inhibitors of the conversion of AA to the 2-series eicosanoids. In particular changes in the relative proportions of AA, LA and DHA in myocardial NEFA are associated with alterations in the production of myocardial thromboxane (TXA 2) and the vulnerability of the heart to develop arrhythmia during partial ischaemia. These results suggest a link between the type of dietary fat intake, the composition of myocardial NEFA and the development of the lethal arrhythmias which are responsible for Sudden Cardiac Death.

Dietary modulation of lipid metabolism and mechanical performance of the heart.

Sudden Cardiac Death resulting from sustained ventricular fibrillation or malignant cardiac arrhythmia has been linked to the type of dietary fat intake in several economically well developed countries where high levels of saturated fatty acids are common. Experimental studies with the small non-human primate marmoset monkey have clearly demonstrated the health benefit of substituting polyunsaturated fatty acids (PUFA's) for dietary saturated fatty acids. Heart rate and blood pressure are lowered, while the left ventricular ejection fraction and the electrical threshold for the induction of ventricular fibrillation are both increased after prolonged feeding of PUFA enriched diets. All these changes in heart function reduce the risk of developing malignant cardiac arrhythmias. The fatty acid composition of cardiac membrane phospholipids is profoundly altered by these changes in dietary lipid intake. In particular the proportions of arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are altered in such a way that the production of myocardial eicosanoids is affected. Although the changes in proportion of these long-chain PUFA's in cardiac phosphatidyl ethanolamine and phosphatidyl inositol are not identical, the shift in balance between these substrates or inhibitors of cyclo-oxygenase activity leads to relatively greater production of prostacyclin (PGI2) than thromboxane (TXA2).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of vasopressin-induced formation of diradylglycerols in vascular smooth muscle cells by incorporation of eicosapentaenoic acid in membrane phospholipids.

Eicosapentaenoic acid and linoleic acid exert antihypertensive effects by an unknown mechanism unrelated to prostanoids, a property which is not shared by arachidonic acid. This study investigated the influence of these three acids on the formation of diradylglycerols and phosphatidic acid, key intracellular messengers involved in the mediation of agonist-induced vascular smooth muscle cell contraction. Rat mesenteric artery vascular smooth muscle cells in culture were pre-incubated for 24 h with eicosapentaenoic acid, linoleic acid or arachidonic acid. After thorough washing the cells were then incubated for 20 min in the presence of arginine vasopressin or vehicle, either immediately or following cell labelling with 32P-orthophosphate. The fatty acid composition of cell lipids was determined by gas chromatography after transesterification in the presence of boron trifluoride and methanol. Diradylglycerols and 32P-phosphatidic acid were purified from cell lipid extracts by thin-layer chromatography and diradylglycerols were analysed. Incubation of vascular smooth muscle cells with eicosapentaenoic acid, linoleic acid or arachidonic acid resulted in the incorporation of these fatty acids at the sn-2 position of membrane phospholipids, mainly phosphatidylcholine and phosphatidylethanolamine. Eicosapentaenoic acid treatment was associated with a reduction, and linoleic acid treatment with an increase in the relative proportions of arachidonic acid found in cell phospholipids. Arginine vasopressin stimulated the formation of both diradylglycerols and 32P-phosphatidic acid. The arginine vasopressin-induced stimulation of diradylglycerols accumulation was almost completely abolished in eicosapentaenoic acid-treated cells, whereas it was not modified by linoleic acid or by arachidonic acid treatment. The arginine vasopressin-stimulated formation of 32P-phosphatidic acid was significantly inhibited by linoleic acid treatment but was not influenced by eicosapentaenoic acid or arachidonic acid treatment. The incorporation of eicosapentaenoic acid or linoleic acid at the sn-2 position of membrane phospholipids leads to an inhibition of arginine vasopressin-induced formation of diradylglycerols or phosphatidic acid, respectively, in rat mesenteric artery vascular smooth muscle cells in culture. These properties may contribute to the antihypertensive effects in these fatty acids in vitro.

Administration Modalities and Intestinal Lymph Absorption of Arachidonic Acid in Rats

We investigated the effects of the proportion of arachidonic acid on lymph lipoprotein synthesis in rats, when infused in the presence of lipids with varying degrees of saturation. A single dose of 90 μmol of lipid was administered intraduodenally and intestinal lymph was collected. Emulsion lipid constituents were 90 μmol of [14C]arachidonic acid alone, or either 30 μmol of [14C]arachidonic acid or 5 μmol of [14C]arachidonic acid and 25 μmol of linoleic acid, with 30 μmol of a free fatty acid and 30 μmol of a monoglyceride (the more saturated: oleic acid + monopalmitin; the more unsaturated: linoleic acid + monoolein). Radioactive lymph recovery of [14C]arachidonic acid infused alone reached 32.6 ° 1.3% of the radioactivity administered and the presence of another fatty acid and a monoglyceride increased it from 38.7 ° 2.6 to 51.9 ° 1.1%. For 30 μmol of arachidonic acid, integration into lymph phospholipids was higher when arachidonic acid was infused with oleic acid and monopalmitin than with linoleic acid and monoolein (7.3 ° 2.7 and 2.8 ° 0.2% at the absorption peaks, respectively), and it was 4.8 ° 0.5% when arachidonic acid was infused alone. For 5 μmol of arachidonic acid, the degree of unsaturation of the added lipid did not modify phospholipid incorporation, which was maintained at 6.9 to 7.2%. The proportion and size of chylomicrons increased with the degree of lipid emulsion unsaturation. Percentages of [14C]phospholipids and of chylomicrons were highly correlated. The proportion of arachidonic acid and degree of lipid emulsion unsaturation affected lymphatic arachidonic acid absorption modalities.

5c,11c,14c-eicosatrienoic acid and 5c,11c,14c,17c-eicosatetraenoic acid of Biota orientalis seed oil affect lipid metabolism in the rat.

The effects of 5c,11c,14c-eicosatrienoic acid (20:3BSO) and 5c,11c,14c,17c-eicosatetraenoic acid (20:4BSO), polyunsaturated fatty acids (PUFA) contained in Biota orientalis seed oil (BSO), on lipid metabolism in rats were compared to the effects of fats rich in linoleic acid (LA) or alpha-linolenic acid (ALA) under similar conditions. The potential effect of ethyl 20:4BSO as an essential fatty acid also was examined in comparison with the ethyl esters of LA, ALA and gamma-linolenic acid (GLA). BSO- and ALA-rich fat decreased the concentration of plasma total cholesterol, high density lipoprotein cholesterol, triglyceride and phospholipid as compared to LA-rich fat. BSO was more effective in reducing plasma cholesterol concentrations than was the ALA-rich fat. Dietary BSO markedly decreased the hepatic triglyceride concentration as compared to the LA-rich or ALA-rich fats. Aortic production of prostaglandin I2 tended to decrease in rats fed BSO or ALA-rich fat compared to those fed the LA-rich fat. Adenosine diphosphate-induced platelet aggregation was similar in the three groups. The proportion of arachidonic acid (AA) in liver phosphatidylcholine (PC) of rats fed BSO was lowest compared to that of rats fed ALA-rich or LA-rich fats. Administration of 20:4BSO, ALA or GLA to essential fatty acid-deficient rats decreased the ratio of 20:3n-9 to AA in liver PC to the same extent; administration of LA was more effective. The results indicate that the effects of specific PUFA contained in BSO on lipid metabolism are different from those of LA and ALA. It is also suggested that 20:4BSO may exhibit some essential fatty acid effects.

Dietary (n-3) Fatty Acid and Vitamin E Interactions in Rats: Effects on Vitamin E Status, Immune Cell Prostaglandin E Production and Primary Antibody Response

To examine the interaction between dietary fat and vitamin E at the level of the rat immune system, a 2 × 3 factorial study was designed. Weanling female Sprague Dawley rats were fed for 8–9 wk diets that contained either corn oil (CO diet) or fish oil (FO diet) and one of three levels (30, 300, 900 mg/kg) of all-rac-α-tocopheryl acetate. At the lowest level of dietary vitamin E, α-tocopherol content of splenocytes from FO-fed rats was ∼40% lower (P < 0.05) than in those from CO-fed rats. Supplementation with all-rac-α-tocopheryl acetate elevated α-tocopherol in splenocytes from FO-fed rats but not in those from CO-fed rats, and reduced the relative proportion of arachidonic acid and eicosapentaenoic acid in the serum of CO-fed and FO-fed rats, respectively. Prostaglandin E production by isolated immune cells was not affected by all-rac-α-tocopheryl acetate supplementation. However, feeding the FO diet consistently reduced prostaglandin E synthesis by 70–80% as compared with the CO diet. Antibody production against sheep RBC was highest in rats fed the FO diet supplemented with 900 mg all-rac-α-tocopheryl acetate/kg of diet. However, antibody response was not directly correlated to diet-induced changes in immune cell prostaglandin E production or α-tocopherol content. Our data suggest that there are significant interactions between vitamin E and (n-3) fatty acids that affect the immune system and that further research in this area is warranted.

Effect of cadmium on lipid components: relation of cadmium to thyroid hormone and growth hormone

To clarify the relationship of cadmium (Cd), thyroid hormone (TH) and growth hormone (GH) to lipid components, 4-week-old SD rats were dosed orally with Cd (CdCl2) at a dose of 2.0 mg/kg body weight five times a week, orally with TH at a dose of 2.5 mg/kg body weight five times a week and subcutaneously with GH (somatotropin) at a dose of 1.0 IU/kg body weight three times a week, all for 4 weeks. As lipid components, the serum concentrations of triglycerides, free fatty acids, lipid peroxides and long-chain fatty acids were determined. We have devised a new method for determining the fatty acid composition in the femur using gas chromatography-mass spectrometry and made a simultaneous analysis of fatty acids, from myristic acid (C14:0) to cholesterol. The results of the present study led to the following conclusions. 1. Cd may inhibit lipogenesis by binding with SH of coenzyme A, thereby reducing the serum levels of free fatty acids and lipid peroxides. 2. When TH and Cd were administered in combination, the addition of Cd produced an inhibitory effect on lipid components, although TH given alone stimulated the lipid metabolism. Therefore, Cd and TH may have an interaction in lipid components. 3. When GH and Cd were administered in combination, Cd modulated the action of GH, which enhanced the effect of somatomedin on the lipid metabolism. The inhibitory effect of Cd on somatomedin activity via Zn was suggested. 4. A sex difference was found in the composition of fatty acids in blood. The males had higher proportions of palmitic acid (C16:0) and linoleic acid (C18:2), while the females had a higher proportion of arachidonic acid (C20:4). There was no sex difference in fatty acid composition in the femur. 5. It was confirmed that TH produced a peroxide of dehydrocholesterol, a precursor of vitamin D3, in the diaphysis of the femur in the increased metabolic state.

Changes in Lipid Composition of Human Peripheral Blood Lymphocytes Infected by HIV

The possible differences in lipid composition between human immunodeficiency virus- (HIV) infected and uninfected PHA-activated human peripheral blood mononuclear cells (PBMC) have been studied. The total fatty acid composition was similar, except for the proportion of arachidonic acid, that was slightly higher in infected than in noninfected cells. No significant differences were obtained in the incorporation of radiolabeled stearic or oleic acids in the different lipid classes. The staining of cells with Nile Red showed similar amounts of intracytoplasmic lipid droplets. On the contrary, the CH/PL ratio, the major factor in determining cell membrane fluidity, was clearly higher in infected than in uninfected cells (0.60 and 0.36, respectively). This fact is discussed in relation with the known high CH/PL ratio (0.95) of the lipid envelope of HIV.

Effect of palm oil on lipid and lipoprotein metabolism and eicosanoid production in rats

Palm oil (PA), which is very rich in palmitic acid, influenced the serum cholesterol concentration and tissue eicosanoid profile of rats characteristically. It increased the serum cholesterol concentration compared with safflower oil (SA), but the degree of the elevation was moderate compared with that of olive oil (OL). The proportion of arachidonic acid in tissue lipids was by no means lower on a PA diet than on an SA diet. The ratio of prostacyclin produced by the aorta to thromboxane A2 in plasma was not simply predicted by the dietary level of saturated fatty acid. PA tended to facilitate the utilization of arachidonate for prostacyclin in vitro in peritoneal macrophages compared with SA. Fatty acid profiles of PA rather than the glyceride structure or the tocotrienol appeared to be the major determinant for the specific features of lipid metabolism observed in rats fed PA.

Effect of monensin on the lipid composition of Achlya bisexualis

Addition of various concentrations of monensin (1, 5 and 10 μg/ml) to the culture medium induced changes in the lipid composition of Achlya bisexualis . The total amount of lipids and sterols was reduced, whereas phospholipids were increased. In the phospholipid fraction, the proportion of arachidonic acid (C 20–4 ) was markedly increased in a dose-dependent manner.