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At least 937 records · Page 52Linked to original sources
PubMed1985

Mature and immature synaptosomal membranes have a different lipid composition.

Subfractionation of the optic tectum in chick embryos results in the isolation of two fractions enriched in synaptosomes (fraction A and fraction B). In chicks after hatching, this fractionation results in the isolation of a single synaptosomal fraction (fraction B) and of a fraction enriched in myelin membranes devoid of synaptosomes (fraction A). The lipid composition of synaptosomal fractions (A and B) and corresponding synaptosomal plasma membranes has been analyzed and compared to the lipid composition of similar fractions isolated from 2-3 day-old chicks. The phospholipid composition of fraction A in embryos was mainly represented by phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The PE content was significantly lower than that of PC, which accounted for by approximately 50%. Sphingomyelin (SP) and phosphatidylinositol (PI) accounted for by only 6% of the total membrane phospholipids. Fraction A isolated from the young chicks showed many significant changes. PC accounted for by approximately 40% and PE made up 35%. The amount of phosphatidylserine (PS) and SP increased. These data parallel our previous morphological observations, which showed that fraction A contains immature synaptosomes in embryos but myelin membranes and no synaptosomes in the young chicks. Fraction B has been shown to contain synaptosomes at all stages considered. It possessed in embryos a lipid composition similar to fraction A, except that PC content was higher in young embryos. The analyses on membrane fractions confirmed these results. On the contrary, this fraction showed many significant changes after hatching. The content of PC was significantly reduced, PE/PC ratio was significantly increased as well as ethanolamine plasmalogen (PLE) content. The percentage of PS, PI and SP were increased. The composition of fatty acids of the total fraction of phospholipids was also examined. The results parallel the observations on phospholipid classes.

Age Factors↗
PubMed1981

Neonatal hypothyroidism and early undernutrition in the rat: defective maturation of structural membrane components in the central nervous system.

The action of neonatal hypothyroidism and early undernutrition on the lipid and protein composition, as well as, on the activity of 2'3' cyclic nucleotide 3' phosphohydrolase was studied in different subcellular fractions isolated from 20 day old hypothyroid and undernourished rats. Based on protein content, a marked decrease (70%) in the recovery of myelin was observed in both experimental conditions. The lipid composition of myelin in both groups was, however, different; while cholesterol, total phospholipids, and total galactolipids decreased in a similar fashion in the two situations; sulfatides and plasmalogens were much more affected in hypothyroid rats.

Animals↗
PubMed1988

Studies on the submicrosomal fractions of bovine oligodendroglia: lipid composition and glycolipid biosynthesis.

Oligodendroglia were isolated from bovine brain, and a "crude" microsomal fraction obtained from cell homogenates was subfractionated into myelin (MP), plasma membranes (PM), Golgi (GF), smooth (SER) and rough (RER) endoplasmic membranes using discontinuous-sucrose gradient centrifugation. The submicrosomal fractions were characterized by ultrastructural examination and analysis of the specific organelle markers. The myelin and plasma membrane rich fractions contained characteristically the highest amounts of the lipid with lower mole percentages of total phospholipids and phosphatidylcholine, and higher concentrations of phosphatidylethanolamine (+ plasmalogens), cholesterol and galactolipids. Considerable amounts of the typical myelin galactolipids (galacto-cerebrosides, sulfatides and monogalactosyl diglycerides) were also found in the Golgi fraction (GF). The GF fraction had the greatest enrichment of glycolipid-forming galactosyltransferases, and the distribution of these enzymes correlated well with that of the Golgi marker enzymes. The results give evidence that intracellular Golgi apparatus of oligodendroglia is rich in the myelin-specific lipids, and suggest its involvement in the synthesis and processing of myelin lipids.

Animals↗
PubMed1987

Day-night cycle of lipidic composition in rat cerebral cortex.

A study of the lipidic pattern of the cerebral cortex of the normal adult rat during the day-night cycle was carried out. The changes observed were the following: phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine plus phosphatidic acid showed a peak at 16:00 hr possibly due to a general increase in phospholipid biosynthesis. During the nocturnal period the variations of phosphatidylcholine and phosphatidylethanolamine were not clearly observed, they might be due to an increase in the interconversion or exchange reaction, since the ratio phosphatidylcholine/phosphatidylethanolamine showed a significative change at 04:00 hr. This occurred because small but opposite changes in both phospholipids were observed, suggesting an increase in the methylation reactions of phospholipids. Cardiolipin showed a significant peak at 04:00 hr. Plasmalogens exhibited significative changes, an important diminution at 16:00 hr and a prominent peak at 24:00 hr. Cholesterol levels were high during the light period and low in the dark one. Cerebrosides and gangliosides showed no day-night variations. The changes observed indicate a phenomenon of biological rhythmicity synchronized by the photoperiod, suggesting that these fluctuations could act as physiological modulators of the properties and functions of the nerve cell membrane.

Animals↗
PubMed1991

Peroxisomal localization of the immunoreactive beta-oxidation enzymes in a neonate with a beta-oxidation defect. Pathological observations in liver, adrenal cortex and kidney.

A boy born to healthy, unrelated parents, presented at birth with hypotonia and seizures. Very long chain fatty acids in the plasma were strongly elevated; bile acid intermediates and plasmalogen biosynthesis were normal. Acyl-CoA oxidase activity was normal. The patient died at the age of 3 months. The cerebellum and medulla oblongata showed neuronal migration defects. The specific biochemical basis for the impaired peroxisomal beta-oxidation has not been found. The three immunoreactive peroxisomal beta-oxidation enzymes and catalase were localized in the hepatocellular peroxisomes. Aberrant features of the peroxisomes included: a subpopulation of organelles larger than 1 micron, an amorphous nucleoid in many organelles, and invaginations of the peroxisomal membrane into the matrix. Peroxisomes in the proximal renal tubules also contained the three immunoreactive beta-oxidation enzymes. Regularly spaced trilamellar inclusions were seen in hepatic macrophages; they were much more abundant in adrenocortical macrophages. The inclusions were birefringent and resistant to acetone extraction. Distinct hepatic fibrosis had developed over a period of 2.5 months. We speculate that the impaired beta-oxidation is due to a defect at the level of the peroxisomal carnitine octanoyl or -acetyl transferase, responsible for the export of beta-oxidation products.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Effect of endothelin-1 induced ischemia on peroxidative damage and membrane properties in rat striatum synaptosomes.

Synaptosomes obtained from rat striata lesioned by central injection of endothelin-1 (ET-1) were analyzed for the levels of lipid peroxidation products, the susceptibility to lipid peroxidation, the phospholipid and free fatty acid composition and the activity of Na+,K(+)-ATPase one hour after ET-1 treatment. The intrastriatal injection of ET-1 promoted an increase of endogenous thiobarbituric reactive substances (TBARS), as index of free radical mediated lipid damage, and a greater susceptibility to iron/ascorbate-induced lipid peroxidation. The pattern of free fatty acids showed a significant decrease of arachidonic and docosahexaenoic acid consequent to ET-1 treatment. The analysis of lipid composition showed a significant loss of phospholipids: among phospholipid species, sphingomyelin and phosphatidylethanolamine plasmalogen were particularly reduced by ET-1 treatment. The activity of membrane-bound Na+,K(+)-ATPase was also significantly reduced in synaptosomes obtained from ET-1 lesioned striata. Taken together these results indicate a significant modification of synaptosomal membrane of ET-1 treated rat striata, possibly due to a free radical mediated damage.

Animals↗
PubMed1985

Renal cortical brush-border and basolateral membranes: cholesterol and phospholipid composition and relative turnover.

A new procedure for the rapid isolation of renal cortical brush-border and basolateral membranes from the same homogenate is described. Brush-border membranes isolated using Mg2+-EGTA precipitation were enriched 18-fold for leucine aminopeptidase and had a recovery of 32.5%. Basolateral membrane fractions were isolated using a discontinuous sucrose gradient and showed an enrichment of 10.7-fold and recovery of 12.8% using (Na+,K+)-ATPase as a marker enzyme. Lipid analysis using two-dimensional TLC separation of phospholipids and gas liquid chromatography for cholesterol showed marked differences in the lipid composition of the brush-border and basolateral membranes. The brush-border membrane had increased sphingomyelin, phosphatidylserine, ethanolamine plasmalogens, and an increased cholesterol-to-phospholipid and sphingomyelin-to-phosphatidylcholine ratio compared to the basolateral membrane. The relative turnover of total membrane and individual phospholipid species using a double isotope ratio method was carried out. Phospholipids were labeled with either phosphorus 32 and 33 or acetate (3H, 1-14C). The relative turnover of phospholipid species and cholesterol differed strikingly. Phosphatidylcholine showed a high turnover, phosphatidylethanolamine and phosphatidylinositol had intermediate values and sphingomyelin, phosphatidylserine and cholesterol had low relative turnover rates. The order of phospholipid class relative turnover was independent of the labeled precursor used. The brush-border membrane had a significantly reduced relative turnover rate for total membrane phospholipids, sphingomyelin and cholesterol compared to the basolateral membrane. These data show marked differences in the lipid composition and relative turnover rates of the phospholipid species of the brush-border and basolateral membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

[Xanthine oxidase in homogenized cow's milk and Oster's hypothesis: a review].

Oster has postulated that the enzyme xanthine oxidase in homogenized cow's milk is the cause of myocardial infarction and angina pectoris. This enzyme may be absorbed by ingestion, especially of the small particles of the fat globules, and then carried by lymph streams to the arterial vascular system, where it is deposited into the myocardium. Then it destroys the aldehydes liberated from the cell membrane-based plasmalogens. This results in the intimal damage to the cell membranes of the arterial intima and the myocardium and ultimately in the development of typical atherosclerotic lesions in the arteries. The presented review is a critical approach to this hypothesis. The following factors are discussed: - the influence of conditions prevailing in the intestine and the stomach on the activity of the xanthine oxidase in milk, - the possibility of this enzyme being absorbed in the intestine, - the formation of antibodies against absorbed xanthine oxidase and - the behaviour of xanthine oxidase administered intravenously. Compared with present knowledge, this theory gives little evidence only.

Absorption↗
PubMed1996

Effects of clofibrate on lipids and fatty acids of mouse liver.

Clofibrate administration significantly altered the amount and fatty acid composition of lipids in mouse liver. The net content of phospholipids (PL) increased and that of triacylglycerols (TG) decreased concomitantly with liver enlargement in mice treated for two weeks with this drug (0.5% w/w in the food). The highest increase among PL was in phosphatidylcholine; other components either showed lower increases or, as in the case of sphingomyelin and the plasmalogens, decreased. In all lipid classes the treatment resulted in altered ratios between major saturates, between saturates and monoenes, and between major polyenes. Among these, 20:3n-6 and 22:5n-3 increased several-fold, and the 20:3n-6/20:4n-6 and 22:5n-3/22:6n-3 ratios increased due to a more active formation of the precursors than of the corresponding products. This change affected all glycerolipid classes. Liver sphingomyelin showed a relative enrichment in monoenoic fatty acids like 22:1 and 24:1, caused by a net decrease in the amount of saturates, particularly 22:0 and 24:0. The stimulated membrane proliferation imposed by clofibrate must increase phospholipid synthesis and, hence, the need for fatty acids. The results suggest that these demands are met mostly by TG acyl groups, either directly or after oxidation/desaturation processes. This was apparently the case for the polyenoic fatty acids of the n-6 and n-3 series. The longer chain (C22 and C24) components decreased, suggesting that their oxidation was stimulated to provide part of the required (C20 and C22) polyenes.

Animals↗
PubMed1996

Quantitative 31P nuclear magnetic resonance analysis of the phospholipids of erythrocyte membranes using detergent.

31P Nuclear magnetic resonance (NMR) spectra of human erythrocyte lysates dissolved in sodium cholate were acquired. The narrow resonances of phospholipids were mostly well resolved, allowing identification and accurate quantitative analysis of phospholipid classes of the erythrocyte membranes. The ether-linked phosphatidylethanolamine components of the erythrocyte membranes were identified, based on the removal of plasmalogens by acidolysis and of diacyl phospholipid species by degradation using phospholipase A1. It was also shown that the introduction of double bonds on the acyl chains of phosphatidylcholine shifted the 31P NMR resonances to lower frequencies. Quantitative analyses of phospholipids from the spectra were based on their apparent molar concentrations. The recoveries of phospholipids from erythrocytes were significantly higher than those using conventional extraction procedures.

Cell Extracts↗
PubMed1996

Isolated dihydroxyacetonephosphate-acyl-transferase deficiency in rhizomelic chondrodysplasia punctata: clinical presentation, metabolic and histological findings.

UNLABELLED: Rhizomelic chondrodysplasia punctata (RCDP) is clinically characterized by symmetrical shortening of the proximal limbs, contractures of joints, a characteristic dysmorphic face, and cataracts. In the classical form an impairment of several peroxisomal functions and enzymes (plasmalogen synthesis, phytanic acid oxidation, 3-oxoacyl-CoA thiolase) has been repeatedly shown. Recently a variant involving only the peroxisomal dihydroxyacetonephosphate acyltransferase (DHAP-AT) has been described. We present a patient with isolated DHAP-AT deficiency and all clinical, radiological and pathological features of classical RCDP. For the first time, microscopy and immunocytochemistry of hepatocytes could be performed. CONCLUSION: In contrast to studies on classical rhizomelic chondrodysplasia punctata which have shown enlarged peroxisomes in numbers varying from hepatocyte to hepatocyte, the peroxisomes in our patient seem to be normal in size, number and shape.

Acyltransferases↗
PubMed1975

Fatty acid and aldehyde composition of major phospholipids in salt gland of marine birds and spiny dogfish.

The lipophilic components of choline phosphoglycerides and ethanolamine phosphoglycerides obtained from the salt gland of herring gull and eider duck and from the rectal gland of spiny dogfish were investigated by means of thin-layer chromatography, gas chromatography, and gas chromatography-mass spectrometry. All phospholipids analyzed were shown to contain small amounts of plasmalogens, and mainly C16, C18, and C18:1 aldehyde was detected. The fatty acids were composed of saturated, unsaturated, straight chain, and branched chain types, ranging between 14-22 carbon atoms. The lipophilic composition of the rectal gland phospholipids showed a higher degree of unsaturation and the presence of more branched chain fatty acids than that of the birds, possibly related to body temperature.

Aldehydes↗
PubMed1976

Lipid composition of rat sciatic nerve.

In the course of our study on the lipids of the rat sciatic nerve, the analysis of the neutral lipids allowed us to detect and characterize cholesteryl esters present at a relatively high level (5%). Among the phospholipids, ethanolamine phosphoglyceride is the most abundant fraction and contains neraly all the plasmalogens (20% of total lipid phosphorus). The glycolipids consist of five different fractions; the cerebrosides with hydroxy fatty acids account for 38% of total glycolipids. Monogalactosyl diglyceride represents 7% of total glycolipids.

Animals↗
PubMed1977

Ether-linked glycerolipids in human brain tumors.

In this investigation, the lipid composition of a number of human brain tumors was determined and compared to that of normal adult brain. Glioblastomas (11 samples), astrocytomas (4 samples), an acoustic neurinoma, an oligodendroglioma, and a meningioma were analyzed. All of the tumors had substantial levels (0.8-3.4% of total phospholipids) of choline plasmalogen which was present in only trace amounts in normal brain. With the exceptions of the acoustic neurinoma and the meningioma, the concentration of alkylacylglycerophosphorylcholine was also higher in the tumors than in normal brain. Neutral lipids of brain tumors also contained high concentrations of both alkyl (1.6-4.8% of total neutral gsults from this investigation indicate that increases in ether-linked glycerolipids may be characteristic of human brain tumors.

Astrocytoma↗
PubMed1979

Effects of diets high in saturated fat and cholesterol on the lipid composition of canine platelets.

The phospholipid composition of platelets from dogs on various experimental diets was determined. Thyroidectomized foxhounds were fed a control diet or the control diet supplemented with (1) beef tallow, (2) beef tallow and cholesterol, or (3) beef tallow, cholesterol, and safflower oil for 23 weeks prior to isolation of platelets. Platelets from animals fed the control diet contained 36.7% phosphatidylcholine (PC), 22.8% phosphatidylethanolamine (PE), 18.4% sphingomyelin (Sph), 11.8% phosphatidylserine (PS), 6.3% phosphatidylinositol (PI), and 2.2% lysophosphatidylcholine. The PE was 77.6% in the plasmalogen form. No highly significant changes in the phospholipid class composition resulted from the experimental diets. Cholesterol supplementation of the diets, however, caused consistent alterations in the fatty acid compositions of the platelet phospholipids including increases in the percentages of 18:1 omega 9 (oleic acid), 18:2 omega 6 (linoleic acid), and 20:3 omega 6 (homo-gamma linolenic acid) and a decrease in the percentage of 20:4 omega 6 (arachidonic acid). Addition of safflower oil to the tallow-cholesterol diet partially reversed these effects. These cholesterol-induced alterations in fatty acid composition could be due to exchange with plasma lipids, de novo synthesis, or altered platelet metabolism. The mechanism remains to be determined.

Animals↗
PubMed1979

Lipid composition of SV40-induced transplantable hamster tumor.

The analysis of the lipid composition of the SV40-induced transplantable hamster tumor has shown that: (a) the total phospholipid content in the tumor is lower than that usually found in normal tissues and similar to that reported for other neoplasms; (b) except for a lower percentage of diphosphatidylglycerol, the phospholipid composition is comparable with that reported for normal tissues; (c) the fatty acid profiles of the various glycerophospholipid classes are characterized by high proportions of oleic acid; and (d) phosphatidylethanolamine contains proportions of alkenyl side chains which are consistent with the amounts of plasmalogenic phospholipids found in other neoplasms.

Animals↗
PubMed1985

Lipid composition of different areas of murine brain: effects of lipid extraction procedures.

The effects of various chemical extraction procedures on the determination of lipid composition of rat and mouse brain have been investigated. Tissue extractions with formic acid/acetone or perchloric acid both resulted in significant losses of total phospholipids and cholesterol. Perchloric acid extraction also degraded, almost quantitatively, ethanolamine plasmalogens to lysophosphatidylethanolamine. Our findings have thus demonstrated that conventional procedures used for extraction of brain tissue for analysis of choline and acetylcholine content cannot also be used for concurrent/simultaneous extraction of phospholipids and cholesterol from the same tissue.

Animals↗
PubMed1983

Systematic protocol for the accumulation of fatty acid data from multiple tissue samples: tissue handling, lipid extraction and class separation, and capillary gas chromatographic analysis.

A systematic procedure was developed for detailed fatty acid profiling of both neutral and polar lipid fractions isolated from hundreds of related bovine muscle and adipose tissue samples. A regimen was established for a nonbiased handling of tissue samples, which included their handling in a predetermined random order. Lipid class separation was accomplished concomitantly during the extraction of the tissues by a selective dry column method, which allowed a detailed analysis of minor but important polyunsaturated fatty acids associated with the polar fraction. Neutral lipids were derivatized to fatty acid methyl esters (FAME) by a literature procedure. However, to protect against lysis of plasmalogens in the polar fraction, a modified nonacidic esterification procedure was developed. FAME profiles were obtained on a programmable high resolution capillary gas chromatograph (GC). Run programs for unattended GC operation and data storage are described. By this overall procedure, the quantitation and peak identification were obtained for major and minor fatty acid constituents from bovine tissue in a manner that prepares for valid statistical interpretation of the resulting data.

Adipose Tissue↗