Abnormalities of erythrocyte stromal lipids in atresia of the intrahepatic bile ducts

Detailed analysis of plasma and erythrocytes lipid composition of patient with intrahepatic biliary atresia is presented. Abnormalities have been outlined and are characterized as following: (1) an increase of total cholesterol compounds and total phospholipids in serum; (2) an increase of free cholesterol and lecithin up to 50 per cent of total phosphatides in red cells; (3) the fatty-acids pattern isolated from total phospholipids of red cells shows a rise of palmitic and palmitoleic acids and a decrease of stearic and longer-chain fatty acids; (4) in PC and PE of red cells, there is an overall tendency for the degree of unsaturation of long-chain fatty acids to increase. In addition to these lipid changes, it was demonstrated by polyacrylamide-gel electrophoresis that the composition of membrane proteins was normal. It is of particular interest to establish whether these abnormalities are either induced by complex metabolic pathways and exchange processes between the lipids of circulating erythrocytes and the altered lipids of serum environment or are the direct result of modified hepatic cellular or enzymatic function.     

Fatty acids of glycerophosphatides in developing chick embryonic brain and liver

Fatty acid compositions of glycerophosphatides of developing chick embryonic brain and liver were compared. In brain, ethanolamine and serine glycerophosphatides contained 30-40% polyunsaturated fatty acids, lecithin almost none (except for arachidonic). In the liver, these acids were equally distributed in the phospholipid fractions. The principal polyunsaturated fatty acids of the ethanolamine and serine glycerophosphatides in brain, liver, and yolk were 22:6, 20:4, and 18:2, respectively. During embryonic development of brain from the 8th day of incubation to hatching, the fatty acid composition of individual glycerophosphatide fractions remained constant. Because of the relative increase of ethanolamine glycerophosphatides and decrease of lecithin, total glycerophosphatides showed a decrease in 16:0 and an increase in 18:0. Substantial amounts of palmitaldehyde and stearaldehyde were present on the 8th day of incubation in the brain ethanolamine glycerophosphatide fraction. During the 3rd week of incubation, the liver showed a two-fold increase in the relative amount of 18:2 in all glycerophosphatide fractions. A decrease of 16:0 in the lecithin fraction and consequently in total glycerophosphatides was also observed during this period. No significant changes in glycerophosphatide fatty acids were observed in the yolk throughout incubation.     

Prostaglandin precursor fatty acids in serum and bile as influenced by oophorectomy, contraceptive steroids and pregnancy. An experimental study in the cat

Variations in the occurrence of prostaglandin precursor fatty acids might be of importance for the pathogenesis of gallstones. Pregnancy and use of contraceptive steroids increase the risk of gallstones. The present study reports the relative fatty acid composition in serum and biliary phospholipids studied by gas-liquid chromatography in four groups of female cats, which were on a standard diet: 1) oophorectomized animals, 2) animals on contraceptive steroids, 3) pregnant animals and 4) control animals. It was consistently found that the portions of palmitic and linoleic acid were higher and stearic and arachidonic acid were lower in biliary than in serum lecithin. In biliary lysolecithin, sphingomyelin and cephaline there were only small portions of linoleic and negligible amounts of arachidonic acid. Oophorectomy, contraceptive steroids or pregnancy did not induce any gross changes in the fatty acid pattern of lecithin in serum or bile. In animals treated with contraceptive steroids a reduced portion of linoleic acid was seen in the bile lecithin, and in pregnant animals there was a reduction of omega 3 and omega 6 fatty acids in biliary lecithin.     

Influence of dietary fat on the lipid composition of rat brain synaptosomal and microsomal membranes.

The modulation of rat brain microsomal and synaptosomal membrane lipid by diet fat was examined. Brain synaptosomal and microsomal membrane composition was compared for rats fed on diets containing either soya-bean oil (SBO), SBO plus choline, SBO lecithin, sunflower oil (SFO), chow or low-erucic acid rape-seed oil (LER) for 24 days. Cholesterol and phosphatidylcholine levels in both membranes were altered by diet. Diet fat also affected the microsomal content of sphingomyelin. Change in membrane phosphatidylcholine level was related to the relative balance of omega-6, omega-3 and monounsaturated fatty acids within the diets fed. The highest phosphatidylcholine levels appeared in membranes of animals fed on SBO lecithin and the lowest in those fed on LER. Microsomal membrane cholesterol and sphingomyelin content increased by feeding on SBO lecithin. In both synaptosomal and microsomal membranes a highly significant correlation was observed between membrane phosphatidylcholine and cholesterol content. The fatty acyl composition of phospholipids from both membranes also altered with diet and age. Alteration in fatty acid composition was observed in response to dietary levels of omega-6, omega-3 and monounsaturated fatty acids, but the unsaturation index of each phospholipid remained constant for all diet treatments. These changes in lipid composition suggest that dietary fat may be a significant modulator in vivo of the physicobiochemical properties of brain synaptosomal and microsomal membranes.     

Modification of the lipid composition of neuroblastoma C1300 cells using liposomes

An essential increase in the total cholesterol content with a significant growth in the level of its esters was observed in neuroblastoma C1300 cells differentiated by means of 5'-bromodesoxyuridine and incubated for 1 h with lecithin-cholesterol liposomes (1:1 mol/mol). These cells also displayed an increased amount of polyunsaturated fatty acids in the composition of lecithin molecules and the appearance of lysolicethin as well. Incubation of the cells with lecithin liposomes was accompanied by a decrease in the content of cholincholesterol in the cells. In this case the level of cholesterol esters decreased to a greater extent than the level of free cholesterol. In lecithin molecules of these cells there occurred a relative increase of saturated fatty acids. The cells can retain viability and compensate changes caused by cholesterol excess during their incubation with lecithin-cholesterol liposome for 60-90 min. A longer incubation with liposomes results in a sharp drop of cell viability.     

Fatty acid composition of serum lecithin and cholesterol ester in the normal menstrual cycle

Gonadal hormones and the relative fatty acid composition of serum lecithin and cholesterol ester were studied on four occasions during one cycle in twenty-two regularly menstruating women. The most evident change during the menstrual cycle was a decrease in the sum of polyunsaturated fatty acids of the linoleic series in the late luteal phase. Concomitantly an increase in oleic acid as well as palmitic acid was recorded. These changes were considered to be dietary influenced since a shift of the oleic/linoleic acid ratio is often seen when fat is replaced by sugar and some women are known to increase their intake of refined carbohydrates premenstrually. The only correlation found for fatty acids and hormone levels was a correlation of the ratio oleic/linoleic acids and 17-beta-estradiol. This pattern is not seen after administration of exogenous estrogens and obviously there is a discrepancy between endogenous and exogenous estrogens in this context. Whether physiological fluctuations of sex hormones during the menstrual cycle directly influence the fatty acid composition of serum lecithin and cholesterol ester is uncertain. No changes in dihomo-gamma-linolenic acid or arachidonic acid, the major precursors of prostaglandin synthesis were recorded.     

Composition of phospholipids and of phospholipid fatty acids of human plasma

The composition of the phospholipids and of the total phospholipid fatty acids was determined in the plasma of 10 normal subjects. In addition the fatty acid composition of the plasma phosphatidyl ethanolamine, phosphatidyl serine, lecithin, sphingomyelin, and lysolecithin of 6 of the subjects was measured. A wide array of fatty acids was found in the plasma total phospholipid similar to that found previously in red cell total phospholipid. The fatty acid composition in the plasma phospholipids of a given subject reflected that in his red cell phospholipids. Each individual phospholipid displayed a distinctive fatty acid pattern, which was generally similar to that of the corresponding phospholipid of red cells, although some marked differences in individual fatty acid levels between the corresponding phospholipids of plasma and red cells were evident. The high percentage of unsaturated fatty acids found in plasma lysolecithin suggests that this phospholipid did not arise entirely through the enzymatic cleavage of the -fatty acid of lecithin.     

Fatty acid composition of cholesterol esters in brains of patients with Schilder's disease, G M1 -gangliosidosis and Tay-Sachs disease, and its possible relationship to the -position fatty acids of lecithin

Abstract— Cholesterol esters were isolated from cerebral cortex and white matter of patients with Schilder's disease, G_M1-gangliosidosis and Tay-Sachs disease, and the fatty acid composition was determined by gas-liquid chromatography. The fatty acid composition was similar among the three pathological conditions, but it was entirely different from that reported for cholesterol esters of normal brain. Lecithin and ethanolamine phospholipids were isolated from the same brain specimens, treated with snake venom phospholipase A, and the fatty acids at the a’and β-positions of the glycerol moiety were determined separately. The fatty acid composition of cholesterol esters was similar to that of the β-position fatty acids of lecithin of white matter in all samples, and was quite different from those of the a'-position of lecithin, or of the a’or β-position of ethanolamine phospholipids. The results indicate that the source of fatty acids for cholesterol esterification in nonspecific sudanophilic demyelination is different from that in normal brain, and that the most likely source is the β-linked fatty acids of lecithin. There are two possible enzymic mechanisms; activation of phospholipase A and subsequent esterification of the liberated β-position fatty acids to cholesterol, or direct transacylation by lecithin-cholesterol acyl transferase.     

Alterations in erythrocyte membrane lipids in abetalipoproteinemia: phospholipid and fatty acyl composition

Scanning electron microscopic observation revealed that there were wide variations including typical acanthocytes in morphology of erythrocytes from a patient with abetalipoproteinemia. The erythrocyte membrane phospholipids and cholesterol contents from a patient was higher by 25% compared to an age-matched control subject. Analysis of phospholipid composition of red blood cells showed an increase of sphingomyelin (25.1----30.1%) with a concomitant decrease of lecithin (27.5----21.0%). Thus, the sphingomyelin/lecithin ratio was increased dramatically (0.91----1.43). As for fatty acyl chain composition of main phospholipids, an increased percentage of palmitic acid and docosahexaenoic acid and a decreased proportion of arachidonic acid and lignoceric acid were observed for sphingomyelin. There was an increment of palmitic acid which was accompanied with a decrease of linoleic acid in lecithin. On the other hand, no significant difference was shown in the fatty acid composition of phosphatidylethanolamine and phosphatidylserine plus phosphatidylinositol between a patient and control.     

Relationship between (Na + K)-ATPase activity, lipid peroxidation and fatty acid profile in erythrocytes of hypertensive and normotensive subjects

Oxidative stress may play a role in the pathogenic mechanism of essential hypertension. Lipid peroxidation can alter the cellular structure of membrane-bound enzymes by changing the membrane phospholipids fatty acids composition. We investigated the relationship between (Na + K)-ATPase activity, lipid peroxidation, and erythrocyte fatty acid composition in essential hypertension. The study included 40 essential hypertensive and 49 healthy normotensive men (ages 35–60 years). Exclusion criteria were obesity, dyslipidemia, diabetes mellitus, smoking, and any current medication. Patients underwent 24-h ambulatory blood pressure monitoring and blood sampling. Lipid peroxidation was measured in the plasma and erythrocytes as 8-isoprostane or malondialdehyde (MDA), respectively. Antioxidant capacity was measured as ferric reducing ability of plasma (FRAP) in the plasma and as reduced/oxidized glutathione (GSH/GSSG ratio) in erythrocytes. (Na + K)-ATPase activity and fatty acids were determined in erythrocyte membranes. Hypertensives had higher levels of plasma 8-isoprostane, erythrocyte MDA, and relative percentage of saturated membrane fatty acids, but lower plasma FRAP levels, erythrocyte GSH/GSSG ratio, (Na + K)-ATPase activity and relative percentage of unsaturated membrane fatty acids, compared with normotensives. Day-time systolic and diastolic blood pressures correlated positively with lipid peroxidation parameters, but negatively with (Na + K)-ATPase activity. These findings suggest that the modulation of (Na + K)-ATPase activity may be associated with changes in the fatty acid composition induced by oxidative stress and provide evidence of a role for this enzyme in the pathophysiology of essential hypertension.     

Incorporation of acetate into fatty acids and lecithin by lung slices from fetal and newborn lambs

Incorporation of acetate-1-(14)C into phospholipids and fatty acids by lung slices from fetal and newborn lambs and from ewes was studied in vitro. The distribution of radioactivity in the fatty acids of neutral lipids, phospholipids, and lecithin was determined. Acetate-1-(14)C was incorporated into myristic, palmitic, and C(18) fatty acids. Of the lecithin fatty acids, myristic and palmitic were the major radioactive fatty acids. The results indicate that the lung of fetal lambs is able to synthesize lecithin containing saturated fatty acids, a major constituent of pulmonary surfactant. A marked increase in the rate of acetate incorporation into lecithin was observed during maturation, and these rates were higher than those obtained in the ewes. A possible relationship between developmental changes in lecithin biosynthesis and pulmonary surfactant is discussed.     

Composition of phospholipids and of phospholipid fatty acids and aldehydes in human red cells

Improved methods for lipid analysis that have been developed recently were employed to reevaluate the phospholipid composition, the fatty acid and fatty aldehyde composition of the total phospholipid, and the fatty acid composition of the individual phospholipids of normal human red cells. Thirty-three fatty acids and five fatty aldehydes were estimated and tentatively identified in the total phospholipid of normal human red cells. Additional minor components were evident. The major individual phospholipids were isolated by silicic acid thin-layer chromatography and quantified. The fatty acid compositions of phosphatidyl ethanolamine, phosphatidyl serine, lecithin, and sphingomyelin were determined. Each of these phospholipids showed a distinctive and characteristic fatty acid pattern.     

Membrane polyunsaturated fatty acids and lithium-sodium countertransport in human erythrocytes

Two groups of individuals, 26 normotensive normolipemic and 37 normotensive hyperlipemic, all without family history of hypertension have been selected in attempt to demonstrate whether Li-Na countertransport of erythrocytes is influenced by plasma and membrane lipid composition. The maximal rate of Li-Na countertransport was elevated in hyperlipemics (0.344 +/- 0.168 vs 0.220 +/- 0.074 mmol/l erythrocytes/h). This difference is highly significant. Hyperlipemics had different composition of membrane lipids than normals. The most important variations were: increase of palmitic, palmitoleic and total saturated fatty acids (SFA) as well as increase of cholesterol/phospholipids ratio (C/PL); in contrast, hyperlipemics had a reduced amount of linoleic acid and total unsaturated fatty acids (UFA) as well as total polyunsaturated fatty acids (PUFA). Consequently, UFA/SFA and PUFA/SFA ratios were lower than in normals. Li-Na countertransport was negatively correlated with the amount of PUFA (P less than 0.02), whereas it was positively correlated with the following parameters: oleic/linoleic ratio (p less than 0.02), monounsaturated fatty acids/polyunsaturated fatty acids ratio (p less than 0.03) as well as with the SFA + monounsaturated fatty acid/PUFA ratio (p less than 0.03). These findings suggest that the V max of Li-Na countertransport in erythrocytes is influenced by the lipid composition of the membrane.     

Binding to mitochondrial proteins of lecithins containing known fatty acids

Lecithins from livers of normal rats and rats deficient in essential fatty acids were separated into fractions containing mainly 1, 2, 3 or 4 double bonds. The fractions thus produced were dispersed in aqueous buffer by ultrasonic irradiation and their rates of binding to mitochondria, whose lipids had been extracted with aqueous acetone, were measured. The kinetics of this reaction can be explained by an initial Brownian coagulation between lecithin and protein particles followed by a rate limiting interaction of lecithin molecules with the mitochondrial protein. A rate equation for these two steps was derived containing three parameters which represent respectively the rate constant for the coagulation step, the surface area of the mitochondria and the rate constant of the second step. The experimental data was fitted to this equation. The effect of variation in fatty acid composition was most marked on the value of the rate constant of the second step, the interaction of lecithin with mitochondrial protein. Lecithins containing arachidonic acid interacted significantly more slowly than those containing 5, 8, 11-eicosatrienoic acid or mixtures of oleic and linoleic acids. The significance of this difference is discussed in relation to the structural function of the essential fatty acids.     

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.     

THE COMPOSITION OF LIPIDS IN CEREBROSPINAL FLUID OF CHILDREN AND ADULTS

Abstract— The proportions of esterified cholesterol and phosphatidyl ethanolamine in lipids of cerebrospinal fluid (CSF) from children were found to be lower than the corresponcling values for adult CSF. The fatty acid patterns of the cholesterol ester, triglyceride + non-esterified fatty acids and phospholipid fractions all displayed low proportions of linoleate; palmitate and oleate were the principal acids present. The fatty acid composition of these lipid classes for CSF derived from children was similar to that from adult subjects. Degradation of CSF lecithin by snake-venom phospholipase A₂ revealed the saturated acids to be located predominantly in the 1-position with the unsaturated ones mainly in the 2-position.     

Lipid metabolism in fatty liver of lysine- and threonine-deficient rats

Rats were fed a low protein diet deficient in and supplemented with lysine and threonine. Liver lipids contained more lecithin, sphingomyelin, and free fatty acids, and less amino phospholipids in the deficient rats. No variations in fatty acid composition of choline- and ethanolamine-containing phospholipids were found; only palmitic acid was increased in the serine-containing phospholipids of the deficient animals. The incorporation of acetate-(14)C into phospholipids, but not into other liver lipids, was lower in deficient rats. In the plasma of deficient rats the concentration of esterified fatty acids and phospholipids was lower, of free fatty acids higher, than in the controls. The fatty acid composition of depot fat differed from that of liver neutral fat both in deficient and supplemented animals. The results presented establish that multiple metabolic defects resulting from lysine and threonine deficiency accompany the fatty liver. The design of the experiments does not permit conclusions to be drawn regarding the causal relationship between the various alterations in lipid metabolism and the fatty liver.     

Effects of Three Bacterial Infections on Serum Lipids of Rabbits

Alteration of the rabbit serum lipids as a result of three bacterial infections was studied by quantitative thin-layer and gas-liquid chromatography. Anthrax infection slightly changed the serum lipid. Cholesterol did not change, though free fatty acids, triglycerides, and cholesteryl esters doubled, and lecithin increased threefold. Tularemia infection produced drastic changes in the serum lipid content of rabbits, increasing levels of cholesterol over 4-fold, free fatty acids 17-fold, triglycerides 11-fold, cholesteryl esters 2.5-fold, and lecithin almost 3-fold. Pneumococcus infection increased cholesterol 2.5 times, free fatty acids were more than doubled, triglycerides were increased 9.5 times, and lecithin was increased almost 4 times. Gas-liquid chromatographic analysis of the methyl esters of free fatty acids showed only quantitative changes in these acids due to infection. Some possible mechanisms of alteration of serum lipid content are discussed.     

Oxygen-induced changes in pulmonary phospholipids in the rat.

The composition and synthesis of alveolar and lung tissue phospholipids were investigated in normal and oxygen-poisoned rat lungs. Sixty-hour exposure to oxygen increased the total amount of phospholipids in the endobronchial extracts and lung tissue. Phosphatidyl glycerol was identified in both endobronchial extracts and lung tissue. The amount of unsaturated fatty acids in surfactant lecithin and phosphatidyl glycerol was slightly increased in oxygen-poisoned lungs whereas the composition of phospholipids in the endobronchial extracts was not affected by oxygen. After intraperitoneal administration of [32P]phosphate the specific activities of surfactant lecithin and phosphatidyl glycerol were clearly lower in oxygen-treated animals whereas the specific activities of lung tissue lecithin and phosphatidyl glycerol remained unaffected. The synthesis of lecithin from [14C]methionine through N-methyltransferase pathway was markedly depressed in lung slices but increased in liver tissue taken from oxygen-poisoned rats and incubated under oxygen indicating a difference between lung and liver methyltransferase enzymes. In conclusion, the present work suggests impaired synthesis and removal of alveolar phospholipids in oxygen-poisoned rats.     

Molecular species of lecithins of rat heart, kidney, and plasma

The lecithins of the heart, kidney, and plasma of the rat were isolated, and the major molecular species identified and quantitatively estimated by combined thin-layer and gas-liquid chromatographic analyses and specific enzymic hydrolyses. The lecithins of the three tissues differed significantly in the composition, positional distribution, and pairing of the fatty acids. No preferential pairing of any one saturated with any other unsaturated fatty acids was observed. The three tissues contained qualitatively the same molecular species of lecithins. The lecithin profiles of the rat heart and kidney appeared to be unrelated to that of the plasma.