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At least 919 records · Page 51Linked to original sources
PubMed1994

Coenzyme A-independent transacylation in amnion-derived (WISH) cells.

Total membranes or microsomal fractions prepared from the amnion-derived WISH cell line posses a coenzyme A-independent transacylase activity. The transacylase utilizes 1-alkenyl- and 1-alkyl-2-lysoglycerophospholipids as preferred acceptors. Marginal transacylation was observed with 1-acyl-2-lysoglycerophospholipids. The reaction occurred in the presence of ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid and was not affected by phospholipase A2 inhibitors. Both 1-acyl- or 1-alkyl-glycerophosphocholines containing an arachidonoyl residue in the sn-2 position were effective as donors, while 2-oleoyl- or 2-palmitoyl-glycerophosphocholines were ineffective. The presence of the transacylase, the specificity of the substrates, and the stability of the 1-alkenyl bond provide a biochemical model that may explain the increased proportion of a highly enriched arachidonate-containing phosphatidyl-ethanolamine-plasmalogens fraction that is found in amnion at term.

Acylation↗
PubMed1996

Biogenesis and metabolic fate of docosahexaenoic and arachidonic acids in rat uterine stromal cells in culture.

To gain some insight into the mechanisms involved in the opposing effects of arachidonic acid and docosahexaenoic acid on the growth of rat uterine stromal cells (UIII cells), the dynamics of the uptake, conversion, and incorporation of labeled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3), and 22:6(n-3) into lipid pools and phospholipid subclasses were examined. A very active and time-dependent conversion of [14C]18:3(n-3) to higher homologs was observed; 64.7 +/- 0.7 and 11.5 +/- 0.4% of the [14C] radioactivity incorporated in cellular lipids was recovered as 22:5(n-3) and 22:6(n-3) after 72 h incubation, respectively. The distribution of labeled fatty acids obtained after 72 h incubation with [3H]20:5(n-3) was not significantly different from that observed with 18:3(n-3). Arachidonic acid was the major fatty acid formed from [14C]18:2(n-6) and only trace amounts of 22:5(n-6) were detected. When cells were incubated for 72 h with 20:4(n-6), more than 75% of the radioactivity was recovered as arachidonate and slightly higher amounts of 22:4(n-6) and 22:5(n-6) were formed compared to those obtained after incubation with 18:2(n-6). Using both [14C]- and [3H]22:6(n-3), no significant retroconversion of labeled 22:6(n-3) occurred in the cells. More than 90% of labeled 20:4(n-6) and 22:6(n-3) taken up by the cells were esterified into phospholipids, but significant differences in their distribution among phospholipid classes and subclasses were observed. Docosahexaenoic acid was more rapidly and efficiently incorporated into phosphatidylethanolamine than 20:4(n-6) and was principally recovered in plasmalogens. Arachidonic acid was mainly incorporated in the diacyl subclasses of phosphatidylcholine and phosphatidylethanolamine and in phosphatidylinositol. The divergent profiles of these two fatty acids within the phospholipid compartments provide some information for the mechanisms of their opposite effects on UIII cell growth.

Animals↗
PubMed1995

Evidence for indirect utilization of glycine for production of N-bases of glycerophospholipids and sphingolipids in mouse neuroblastoma cells by using 15N-labeled glycine.

After mouse neuroblastoma cells were cultured with [15N]glycine in Dulbecco's modified Eagle's medium for total four days, they gave significant amounts of 15N-atom% excess in phosphatidylserine, phosphatidylethanolamine, ethanolamine plasmalogen, phosphatidylcholine, sphingomyelin and ceramide. These results were compared with those of [15N]choline, [15N]ethanolamine and [15N]DL-serine used in place of [15N]glycine for the experiments. It was suggested that [15N]glycine is taken into the cells and metabolically converted to [15N]L-serine, which is well known to be used for the production of polar head groups of glycerophospholipids and sphingosine.

Animals↗
PubMed1993

Complementation analysis of patients with intact peroxisomes and impaired peroxisomal beta-oxidation.

Complementation analysis, using peroxisomal beta-oxidation of very long chain fatty acids (VLCFA) as the criterion for complementation, is useful in the study of patients who are suspected of having a single enzyme defect in the peroxisomal beta-oxidation pathway. Laboratory findings for these patients include elevated plasma VLCFA and impaired VLCFA oxidation in fibroblasts. Some of these patients have slightly abnormal phytanic acid oxidation in fibroblasts. In addition, elevated levels of bile acid intermediates have been reported in some cases. Plasmalogen synthesis, pipecolic acid levels, and subcellular distribution of catalase are normal. Using complementation analysis, we show that six patients, who were suspected of having a single enzyme defect in the peroxisomal beta-oxidation pathway, are deficient in peroxisomal bifunctional enzyme [enoyl-CoA hydratase (EC 4.2.1.17)/3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35)] activity. This group of six patients, deficient in bifunctional enzyme activity, may be subdivided into two complementation groups. It would appear that patients in each of these two groups are deficient in only one of the bifunctional enzyme activities.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1993

Interferon-gamma-stimulated uptake and turnover of linoleate and arachidonate in macrophages: a possible pathway for hypersensitivity to endotoxin.

When P388D macrophage cells were exposed to [14C]linoleic acid, phosphatidylcholine (PC) phosphatidylethanolamine (PE), phosphatidylinositol (PI), and triacylglycerol (TAG) were major labelled lipid classes. PC was the major labelled phospholipid class at shorter incubation times with PE and PI becoming proportionally better labelled with time. Interferon-gamma (IFN-gamma) stimulated the labelling of all phospholipid classes at the expense of triacylglycerol (TAG) labelling whether it was added coincidently to the [14C]linoleic acid or after a prelabelling period. A similar pattern of labelling of all major phospholipid classes by interferon-gamma in J774.2 macrophage cells was also observed. Interferon-gamma also exerted a stimulatory effect on incorporation of [14C]arachidonic acid into the phosphatidylinositol fraction of the membrane phospholipids. However, uptake of [14C]stearic acid was not different in control compared with IFN-gamma-activated cells. Uptake of linoleic acid into the plasmalogen fraction of PE was also considerably enhanced in IFN-gamma-treated cells. The results suggest that IFN-gamma has a direct effect on the activity of enzymes controlling fatty acid turnover in phospholipids. This altered uptake and turnover of unsaturated fatty acids may have important consequences for the subsequent activation of macrophages by endotoxin.

Animals↗
PubMed1997

Isolation and characterization of peroxisome-deficient Chinese hamster ovary cell mutants representing human complementation group III.

We made use of the 9-(1'-pyrene)nonanol/ultraviolet (P9OH/UV) method and isolated peroxisome-deficient mutant cells. TKa cells, the wild-type Chinese hamster ovary (CHO) cells, CHO-K1, that had been stably transfected with cDNA encoding Pex2p (formerly peroxisome assembly factor-1, PAF-1) were used to avoid frequent isolation of the Z65-type, PEX2-defective mutants. P9OH/UV-resistant cell colonies were examined for the intracellular location of catalase, a peroxisomal matrix enzyme, by immunofluorescence microscopy and using anti-catalase antibody. As six mutant cell clones showed cytosolic catalase, there was likely to be a deficiency in peroxisome assembly. These mutants also showed the typical peroxisome assembly-defective phenotype, including significant decrease of dihydroxyacetonephosphate acyltransferase, the first step key enzyme in plasmalogen synthesis, and loss of resistance to 12-(1'-pyrene)dodecanoic acid/UV treatment. By transfection of Pex2p and Pex6p (formerly PAF-2) cDNAs and cell fusion analysis between the CHO cell mutants, two mutants, ZP104 and ZP109, were found to belong to a novel complementation group. Further complementation analysis using fibroblasts from patients with peroxisome biogenesis disorders revealed that the mutants belonged to human complementation group III. Taken together, ZP104 and ZP109 are in a newly identified fifth complementation group in CHO mutants reported to date and represent the human complementation group III.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1999

Genotype-phenotype correlations in disorders of peroxisome biogenesis.

Genetically determined human peroxisomal disorders are subdivided into two major categories: disorders of peroxisome biogenesis (PBD), in which the organelle is not formed normally, and those that involve a single peroxisomal enzyme. Twelve PBD have been identified, and the molecular defects have been defined in 10. All involve defects in the import of proteins into the organelle. Factors required for this import are now referred to as peroxins (PEX) and form the basis of a new and preferred classification system. The PBD are associated with four clinical phenotypes, named before their association with the organelle was recognized: Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), infantile Refsum disease (IRD), and rhizomelic chondrodysplasia punctata (RCDP). The first three are associated with 9 of the 10 PEX defects that have been defined so far, and represent a clinical continuum with variant severity, with ZS the most severe, NALD intermediate, and IRD the least severe. RCDP is associated with PEX7. Genotype-phenotype correlations are complicated by the fact that the clinical manifestations of the ZS-NALD-IRD continuum can be mimicked by disorders that affect single enzymes of peroxisomal fatty acid oxidation, and PEX7 by disorders of plasmalogen synthesis enzymes. Furthermore, clinical manifestations of each of the PEX disorders may vary. Phenotypic expression varies with the nature of the mutation, the milder phenotypes being associated with mutations that do not abolish function completely, or with mosaicism. Definition of the molecular defects is of great value for genetic counseling and may be of aid in establishing prognosis.

Genotype↗
PubMed1978

The release of free ethanolamine in rat brain homogenates incubated in Krebs ringer.

Ethanolamine in mammalian brain is found chiefly in a lipid-bound form either as the diacyl phospholipid, phosphatidylethanolamine or as the plasmalogen, I-alk-11-enyl-2-acyl glycerophosphoethanolamine and to a lesser extent as the saturated ether analogue. The level of free ethanolamine in brain is very low, probably less than 40 nmol/g brain (Spanner & Ansell, 1977b) while that of phosphoethanolamine is about 1.0 mumol/g brain. Some time ago we found that if brain tissue was incubated in Krebs Ringer bicarbonate (pH 7.4) at 37 degrees, there was a steady release of free ethanolamine by the tissue. The following account is a summary of the findings from experiments designed to determine the source of the ethanolamine liberated.

Animals↗
PubMed1978

The effect of intoxication with alkylnitrosourea derivatives on cerebral myelin.

Adult BD IX rats were injected with methylnitrosourea and pregnant mice on the 15th day of gestation with a single intravenous dose of ethylnitrosourea and pregnant mice on the 15th day of gestation with a single intravenous dose of ethylnitrosourea. The cerebral myelin fraction of adult BD IX rats and of the mice offsprings was studied. It was found that a part of the rats intoxicated with methylnitrosourea developed spongious changes in the cerebral and cerebellar white matter. The myelin fraction of intoxicated rats also showed severe losses of sphingomyelin with a steady increase in the cholesterol ester content. The myelin fraction from mice intoxicated during the foetal development appeared deficient with respect to galactolipids and plasmalogen. It is concluded that, besides the carcinogenic effect, alkylnitrosourea derivatives effectively disturb the lipid metabolism of membrane structures of the central nervous system.

Animals↗
PubMed1989

Phytanic acid alpha-oxidation and complementation analysis of classical Refsum and peroxisomal disorders.

We have measured the production of 14CO2 from exogenous [1-14C] phytanic acid in fibroblast monolayers from patients with classical Refsum's disease and peroxisomal disorders. Activities in the different disorders were (percentage of control): classical Refsum's disease (5%), isolated peroxisomal acyl-CoA oxidase deficiency (75%), Zellweger syndrome (4%), neonatal adrenoleukodystrophy (5%), and rhizomelic chondrodysplasia punctate (3%). Absence of complementation was demonstrated between Zellweger syndrome and infantile Refsum's disease lines after polyethylene glycol fusion, with decreases of average activity of 11% relative to unfused cell mixtures. Classical Refsum's disease, rhizomelic chondrodysplasia punctata, and neonatal adrenoleukodystrophy lines all complemented one another, and Zellweger syndrome or infantile Refsum's disease lines, with average activity increases of 522%-772%. No intragenic complementation was observed within either group. Four complementation groups were detected suggesting that at least four genes are involved in phytanic acid alpha-oxidation: one gene for the enzyme phytanic acid alpha-hydroxylase (probably mitochondrial); one gene for a regulatory factor for the expression of phytanic acid alpha-decarboxylation activity and two membrane-bound peroxisomal enzymes involved in the synthesis of plasmalogens; two genes for the assembly of functional peroxisomes and/or import of proteins into peroxisomes.

Adrenoleukodystrophy↗
PubMed1976

Lipid composition of myelin in multiple sclerosis.

Myelin was isolated from histologically normal white matter and plaques from MS patients and from white matter of neurologically normal controls. No difference was found in the total lipid content. There were no detectable deficits in MS myelin of phosphoglycerides, plasmalogens or sphingolipids. Gangliosides and lysolecithin were not detected. Analysis of the fatty aldehyde composition of the phosphoglycerides and the fatty acid composition of the cholesteryl esters, phosphoglycerides and sphingolipids did not show any differences between the normal and MS myelin.

Cerebrosides↗
PubMed1995

Polyunsaturated fatty acids in the developing human brain, erythrocytes and plasma in peroxisomal disease: therapeutic implications.

Patients with Zellweger syndrome and related peroxisomal disorders have profound changes in the polyunsaturated fatty acid (PUFA) patterns in brain and other tissues, with a constant decrease in docosahexaenoic acid (DHA, 22: 6omega3) concentration. Arachidonic acid (AA, 20: 4omega6) concentration is normal or increased and linoleic acid (LA, 18: 2omega6) is increased in the brain of Zellweger patients. In the retina of these patients, the levels of DHA are extremely low. Since these alterations are reflected elsewhere, they can be detected in vivo in patients with generalized peroxisomal disorders by measuring the PUFA content of plasma and erythrocytes, which show very low concentrations of DHA. The concentration of AA is low in plasma in generalized peroxisomal patients, although it is within normal limits in erythrocytes. Patients with X-linked adrenoleukodystrophy (X-ALD) or adrenomyeloneuropathy (AMN) have a normal DHA and AA content in both plasma and erythrocytes, unless they receive extremely low-PUFA diets. Given the probable role of DHA deficiency in the pathogenesis of Zellweger syndrome (ZS), it is important to normalize concentrations of DHA, at least in blood, in an attempt to correct the DHA deficiency in brain. DHA ethyl ester was given orally to two infants with a peroxisome deficiency disorder for a year, and some favourable biochemical changes were produced in erythrocytes and plasma. Normalization of the DHA concentrations in erythrocytes was obtained in about 2 months, and the ratios 26: 0/22: 0 and 26: 1/22: 0 decreased markedly in plasma in the two patients. The plasmalogen ratio 18: 0 dimethyl acetal/18: 0 in erythrocytes increased to virtually normal values in both patients. There was a clear clinical improvement in the two patients, which paralleled the increase in blood DHA. The concentrations of AA and other PUFAs were closely monitored and, when necessary, AA was added to the diet. Such a DHA therapy, given under close biochemical and clinical control, and accompanied by a diet rich in other long-chain PUFA, is strongly recommended in all patients with peroxisomal disorders in whom a DHA deficiency is detected in blood.

Brain↗
PubMed1994

Isolated dihydroxyacetonephosphate acyltransferase deficiency presenting with developmental delay.

A boy aged 21 months who was being investigated for developmental delay and failure to thrive was found to have punctate epiphyseal calcification. He had no evidence of rhizomelic shortening of the limbs or cataracts. Investigation revealed defective plasmalogen synthesis due to isolated deficiency of dihydroxyacetonephosphate acyltransferase (DHAP-AT). The parents were consanguineous and a sister was similarly affected, suggesting autosomal recessive inheritance. Hitherto, recessively inherited isolated DHAP-AT deficiency has only been described in patients with a phenotype similar to that of rhizomelic chondrodysplasia punctata. This report indicates that the same biochemical disorder can be associated with a less severe phenotype.

Acyltransferases↗
PubMed1994

Phytanic acid alpha-oxidase deficiency (Refsum disease) presenting in infancy.

This report describes a patient with high serum phytanic acid concentration due to phytanic acid alpha-oxidase deficiency (classical Refsum disease). He presented unusually early, hypotonia and developmental delay being apparent by 7 months. A generalized peroxisomal disorder (so-called 'infantile Refsum disease') was excluded by analyses of pristanic acid, very long-chain fatty acids, bile acids and plasmalogen synthesis. The early presentation raises the possibility of in utero exposure to phytanate.

Gas Chromatography-Mass Spectrometry↗
PubMed1981

The organization of gangliosides and other lipid components in synaptosomal plasma membranes and modifying effects of calcium ion.

Synaptosomes were prepared from bovine brain by zonal rotor sucrose density centrifugation. While a major fraction of lipid-bound sialic acid is included uniformly within the synaptosomal distribution profile, the sialoglycoproteins and some gangliosides do not follow this pattern. Exposure to extrasynaptosomal calcium results in alterations in the surface labeling properties of some gangliosides and membrane plasmalogens, suggesting that extrasynaptic Ca2+ may influence the conformation of complex lipids in synaptic plasma membranes. The level of intrinsic membrane-associated sialidase activity that liberates sialic acid from these sialoglycoconjugates parallels the synaptosomal buoyant density distribution profile, supporting a view that this enzyme resides in synaptosomal membranes in close association with a sialolipid substrate.

Animals↗
PubMed1981

Action of phospholipase A2 of rabbit neuronal and glial cells on 1,2-diacyl-, 2-acyl-1-alk-1'-enyl-, and 2-acyl-1-alkyl-glycerophosphatides.

Pronounced differences in the phospholipase A2 activities were found in neurons and glia, the enzyme activity being two- to threefold higher in neurons than in glial cells. Both phospholipases A2 hydrolyzed the 1,2-diacylglycerophosphatides more rapidly than the acylalkyl and acylalkenyl compounds. Choline plasmalogen and the corresponding alkyl derivative were cleaved at similar rates by the phospholipase A2 from both glia and neurons. There was a tendency by the neuronal phospholipase A2 to release arachidonic acid faster than linolenic acid from both phosphatidylcholine and -ethanolamine, while arachidonic acid was removed less actively from phosphatidylethanolamine by the glial enzyme. The glial phospholipase A2 showed a lag period of 10 or 20 min. Norepinephrine, injection into the lateral ventricle of the rabbit brain, stimulated the hydrolysis of the various 1,2-diacyl-, acylalkyl, and and acylalkenyl-glycerophosphatides by the phospholipase A2 from both glia and neurons.

Animals↗
PubMed1985

The effects of temperature- and oxygen-acclimation on phospholipids of goldfish (Carassius auratus L.) brain microsomes.

Brain microsome phospholipids and their acyl groups, from temperature and oxygen acclimated goldfish, were investigated. At the lower acclimation temperature (5C) the proportion of ethanolamine- to choline-glycerophosphatides (GPE/GPC) was increased, and the proportion of phosphatidal ethanolamine value decreased. A rise in the n-6/n-3 fatty acyl group also occurred in cold acclimation. Irrespective of acclimation temperature, 25 degrees C or 5 degrees C, a partial replacement of GPC by GPE occurred when the concentration of oxygen was increased; conversely the GPE/GPC ratio decreased at the hypoxic level. The plasmalogen GPE content increased as the oxygen concentration was raised. A rise in the n-6/n-3 ratio, for ethanolamine glycerophosphatides and phosphatidyl choline, occurred when the oxygen concentration was increased (hypoxia to hyperoxia). It is concluded that the lipid alterations associated with thermal acclimation are, in part, attributable to the concomitant change in oxygen concentration.

Acclimatization↗
PubMed1979

Activity and subcellular distribution of phospholipase A1 from neuronal cell-enriched fractions of the rabbit cerebral cortex.

Glycerophosphatides, specifically labeled either in the 1 or in the 2 position, were used to measure the activity of neuronal phospholipase A1 and to investigate the subcellular distribution of the enzyme. The microsomes were found to possess the highest phospholipase activity, with a threefold increase as compared to the cell homogenate. A considerable enzymatic activity could still be observed in the plasma membranes isolated from the neuronal-enriched cell fraction. Microsomal phospholipase possessed the highest activity with phosphatidylcholine, whereas phosphatidylserine was cleaved at a much lower rate. The rate of release of labeled fatty acids from the substrates by the microsomal phospholipase decreased with increasing degree of unsaturation of the fatty acids at the 1 position. The presence of plasmalogens and of alkylacyl analogues in the incubation mixture caused an appreciable inhibition of the hydrolysis of the diacyl glycerophosphatides.

Animals↗