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At least 883 records · Page 49Linked to original sources
PubMed2002

Differential effects of n-3 fatty acid deficiency on phospholipid molecular species composition in the rat hippocampus.

In this study, we have examined the effects of n-3 fatty acid deficient diets on the phospholipids (PL) molecular species composition in the hippocampus. Female rats were raised for two generations on diets containing linoleic acid (18:2n-6), with or without supplementation of alpha-linolenic acid (18:3n-3) or 18:3n-3 plus docosahexaenoic acid (22:6n-3). At 84 days of age, the hippocampal phospholipids were analyzed by reversed phase HPLC-electrospray ionization mass spectrometry. Depleting n-3 fatty acids from the diet led to a reduction of 22:6n-3 molecular species in phosphatidylcholine (PC), phosphatidylethanolamine (PE), PE-plasmalogens (PLE), and phosphatidylserine (PS) by 70-80%. In general, 22:6n-3 was replaced with 22:5n-6 but the replacement at the molecular species level did not always occur in a reciprocal manner, especially in PC and PLE. In PC, the 16:0,22:6n-3 species was replaced by 16:0,22:5n-6 and 18:0,22:5n-6. In PLE, substantial increases of both 22:5n-6 and 22:4n-6 species compensated for the decreases in 22:6n-3 species in n-3 fatty acid deficient groups. While the total PL content was not affected by n-3 deficiency, the relative distribution of PS decreased by 28% with a concomitant increase in PC. The observed decrease of 22:6n-3 species along with PS reduction may represent key biochemical changes underlying losses in brain-hippocampal function associated with n-3 deficiency.

Analysis of Variance↗
PubMed1979

[Semi-synthesis and proposed structure of platelet-activating factor (P.A.F.): PAF-acether an alkyl ether analog of lysophosphatidylcholine].

We have studied the molecular structure of platelet-activating factor" (P.A.F.), a mediator of inflammation obtained from blood leukocytes, macrophages, and platelets themselves. We have semi-synthetized a substance that possesses all the known physicochemical and biological characteristics of P.A.F. from hog leukocytes. This was performed by successive methylation, hydrogenation, and acetylation of lysophosphatidylethanolamine plasmalogen. We therefore propose the following structure for P.A.F.: 1-0-alkyl-2-acetyl-glyceryl-3-phosphorylcholine. This molecular structure is not yet described among the numerous substances capable of inducing platelet aggregation and release.

Acetylation↗
PubMed1975

Effect of denervation on the phospholipid content in subcellular fractions of tonic and tetanic muscles.

Four weeks after denervation, various changes were observed in the phospholipid composition of the sarcolemmal and sarcoplasmic fractions of skeletal muscles with different functions. Neurotomy also affected the innervated contralateral muscles and produced opposite changes in the phospholipid content of subcellular fractions. The increase in the amount of phospholipids in the sarcolemmal fractions of the denervated muscles was only apparent. The difference between the denervated and contralateral muscles was also due to the decrease of phospholipids in the contralateral muscles. These changes were more pronounced in the tetanic (fast-twitch) than in the tonic (slow-twitch) muscles. In the sarcoplasmic fraction of the denervated tetanic muscle an increase, while in that of the tonic one a slight decrease of phospholipids appeared. In contrast, the phospholipid content in the sarcoplasmic fractions of contralateral muscles did not decrease, while it increased slightly in the tonic muscle. The amount of plasmalogens (fatty aldehyde: lipid phosphorus ratio) decreased only in the subcellular fractions of the denervated muscles while there was no change in those of the contralateral muscles.

Aldehydes↗
PubMed1992

[Biochemical and molecular aspects of peroxisomes].

Peroxisomes contain hydrogen peroxide-forming oxidase(s) and catalase. Mammalian peroxisomes had been considered as a fossil organelle, since other important metabolism was not found. The discovery of a new fatty acid beta-oxidation system in rat liver peroxisomes in 1976 revived a great deal of interest of this organelle. Biochemical features and molecular aspects of individual enzymes of this system are summarized. It has also been elucidated that peroxisomes have important roles in biosynthesis of cholesterol, bile acids, and plasmalogens. These metabolisms together with some oxidases are summarized briefly.

Animals↗
PubMed1992

The primary determinant of rabbit myocardial ethanolamine phosphotransferase substrate selectivity is the covalent nature of the sn-1 aliphatic group of diradyl glycerol acceptors.

Plasmenylethanolamines represent the major endogenous phospholipid storage depot of arachidonic acid in many mammalian cells. To elucidate the biochemical mechanisms contributing to the high plasmalogen content and arachidonic acid enrichment present in myocardial ethanolamine glycerophospholipids, the substrate specificity of rabbit myocardial ethanolamine phosphotransferase (EPT) was quantified utilizing multiple molecular species of each subclass of diradyl glycerol substrate. Myocardial EPT demonstrated over a 16-fold selectivity for 1-O-alk-1'-enyl-2-acyl-sn-glycerol (AAG) compared to 1,2-diacyl-sn-glycerol (DAG) substrate utilizing individual molecular species of each subclass dispersed in Tween 20. The selective utilization of AAG by EPT was substantiated utilizing two independent assay systems which employed either the presentation of substrate to enzyme as a substitutional impurity in Triton X-100 mixed micelles or the obligatory utilization of endogenously generated diradyl glycerol substrates. Although rabbit myocardial microsomes contained over a 20-fold molar excess of endogenous DAG to AAG mass, incubation of rabbit myocardial microsomes with CDP-ethanolamine resulted in the highly selective synthesis of plasmenylethanolamines which were predominantly comprised of molecular species containing arachidonic acid at the sn-2 position (greater than 75%). Endogenous AAG molecular species in rabbit myocardial microsomes were similarly enriched in arachidonic acid, and the distribution of AAG molecular species closely paralleled the distribution of plasmenylethanolamine (but not plasmenylcholine) molecular species. Thus, the subclass and molecular species distribution of the ethanolamine glycerophospholipids synthesized by rabbit myocardial EPT reflects independent contributions from the subclass selectivity of EPT for AAG substrate in conjunction with the enrichment of arachidonic acid in microsomal AAG molecular species.

Animals↗
PubMed2005

31P MRS analysis of the phospholipid composition of normal human peripheral blood mononuclear cells (PBMC).

The aim of this investigation was to characterize the phospholipid composition of normal human blood mononuclear cells using 31P NMR spectroscopy. Mononuclear cells of peripheral blood were obtained from 10 volunteers. Phospholipid extracts were prepared from 60x10(6) cells according to modified Folch's method. An AMX 300 Bruker spectrometer 7.05 T was used. The 31P spectrum of phospholipid extracts from normal human PBMC consisted of 9 peaks, with one each for phosphatidylcholine (PC), plasmalogen of phosphatidylcholine (CPLAS), lysophosphatidylcholine (LPC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL), and another one due to the external reference substance, methylenediphosphonic acid (MDPA). The concentrations of these phospholipids (PL), based on the integral intensities, were as follows: 0.398 +/- 0.078 mmole/l for PC; 0.033 +/- 0.019 mmole/l for CPLAS; 0.155 +/- 0.043 mmole/l for SM; 0.266 +/- 0.104 mmole/l for PI+PE; 0.101 +/- 0.040 mmole/l for PS, and 0.026 +/- 0.033 mmole/l for CL. The results of this study confirmed that 31P MRS is a convenient tool for measuring the phospholipid concentrations of biological samples.

Adult↗
PubMed1991

Rhizomelic chondrodysplasia punctata: 16-year follow-up of a child from birth.

A boy with rhizomelic chondrodysplasia punctata, diagnosed on the laboratory evidence of a high plasma concentration of phytanic acid and a low erythrocyte concentration of plasmalogens, has been followed from birth to the age of 16 years. The clinical pattern (somatic, skeletal and neurological) tallies with published findings in this disease. Unusual findings are the associated epilepsy, confirmed by EEG, and the long survival. CT brain scan and MRI showed cortical and subcortical atrophy but not gyral abnormalities or demyelination.

Brain↗
PubMed1988

Icosanoid production can be decreased without alterations in cellular arachidonate content or enzyme activities required for arachidonate release and icosanoid synthesis.

We have demonstrated that icosanoid production can be inhibited by altering the distribution of arachidonate within the cell, so that it is not released from phospholipids for icosanoid synthesis. This effect was observed in a prostaglandin E2-producing cell line (HSDM1C1) by deprivation of exogenous arachidonate for 24-48 h. Icosanoid production by the cells upon bradykinin stimulation was impaired despite no change in the concentration of arachidonate within the cell and no change in the activity of cyclooxygenase, phospholipases, acyltransferases, or fatty acyl-CoA hydrolase. Associated with the decline in prostaglandin E2 production was an increase in arachidonate incorporation into ethanolamine plasmalogens and a decrease in the activity of the enzyme arachidonoyl-CoA synthetase, which may play a role in compartmentation of arachidonate within the cell. Thus, we have found that a decrease in icosanoid production can be achieved without pharmacologic intervention by a short-term restriction of exogenous arachidonate which leads to redistribution of arachidonate within phospholipids and/or subcellular membranes in the cell.

Acyltransferases↗
PubMed1988

Aberration in de novo ether lipid biosynthesis in peroxisomal disorders.

The Zellweger syndrome is a rare inborn error of metabolism characterized by the absence of morphologically distinguishable peroxisomes. As a consequence tissues and cells from Zellweger patients contain severely reduced levels of ether phospholipids. These are replaced by diacylphospholipids while keeping the polar headgroup composition of the cellular phospholipids constant. Both peroxisomal enzymes involved in glycero-ether lipid bond formation appear to be deficient. The experiments clearly establish that peroxisomes are indispensible for ether lipid biosynthesis. The peroxisomal deficiency in de novo ether lipid biosynthesis in fibroblasts and amniotic fluid cells can be applied in diagnostic assays. The mutation can be by-passed by feeding the cells with alkylglycerol. Similar characteristics as found for plasmalogen biosynthesis in Zellweger syndrome were assessed in other diseases with a general impairment of peroxisomal functions such as infantile Refsum disease and neonatal adrenoleukodystrophy as well as in rhizomelic chondrodysplasia punctata, a disease characterized by the absence of some, but not all, peroxisomal functions. Complementation analysis after somatic cell fusion has revealed that at least three genes must be involved in the biogenesis of fully functional peroxisomes.

Glyceryl Ethers↗
PubMed1985

Semi-synthetic approach for the preparation of homogeneous plasmenylethanolamine utilizing phospholipase D from Streptomyces chromofuscus.

A simple method for the preparation of homogeneous molecular species of plasmenylcholine and plasmenylethanolamine was developed. The method utilized reverse phase high performance liquid chromatography to isolate homogeneous molecular species of plasmenylcholine prepared by acylation of lysoplasmenylcholine. Plasmenylcholine was directly converted to plasmenylethanolamine by transphosphatidylation utilizing phospholipase D from Streptomyces chromofuscus. This method permits the facile labeling of homogeneous molecular species of plasmalogens in the polar head group, the sn-2 acyl chain, or both, for the first time.

Chemical Phenomena↗
PubMed1985

[Synthesis of a fluorescently-labeled platelet activating factor].

The synthesis of fluorescently labelled PAF-acether, 1-alkyl-2-acetyl-sn-glycero-3-phospho-[N-(9-anthrylmethyl)-N, N-dimethylethanolamine] with the label in the choline moiety is described, plasmalogen lysophosphatidylcholine of bovine heart being used as starting material.

Chemical Phenomena↗
PubMed1969

Isolation and identification of phospholipids of bovine rhodopsin.

Phospholipids present in digitonin solutions of bovine rhodopsin have been identified and assayed. Digitonin interferes with extraction of lipids by the usual methods; digitonin was therefore removed from the preparation as an ergosterol digitonide, soluble in absolute ethanol but precipitated in 80% ethanol. The supernatant 80% ethanol contained one portion of the phospholipid, mainly choline and ethanolamine phosphoglycerides with traces of serine phosphoglyceride and sphingomyelin. The rhodopsin residue (free from digitonin) was extracted with chloroform-methanol 2:1; this extract contained the rest of the phospholipid, which consisted only of choline and ethanolamine phosphoglycerides. Plasmalogens were not found, but could have decomposed during the procedures.

Animals↗
PubMed1968

The alk-1-enyl group content of mammalian myelin phosphoglycerides by quantitative two-dimensional thin-layer chromatography.

Myelin phospholipids have been examined by a separation-reaction-separation procedure for two-dimensional thin-layer chromatography on silica gel. After separation in one dimension, alk-1-enyl groups are cleaved by exposure of the plates to HCl fumes. Development in the second dimension quantitatively separates acid-labile and acid-stable phosphoglycerides as well as the aldehydes released from the acid-labile phosphoglycerides. Myelin phospholipids from the central nervous systems of the rhesus monkey, squirrel monkey, ox, and mouse contain 32-36% acid-labile ethanolamine phosphoglycerides (ethanolamine plasmalogens) and 8-14% acid-stable ethanolamine phosphoglycerides. Acid-labile choline and serine phosphoglycerides account for less than 1% of the myelin phospholipids.

Alkenes↗
PubMed1983

Arachidonoyl transacylase in human platelets. Coenzyme A-independent transfer of arachidonate from phosphatidylcholine to lysoplasmenylethanolamine.

Human platelets contain an enzyme that catalyzes CoA-independent release of arachidonic acid from phosphatidylcholine with concomitant incorporation into plasmenylethanolamine. Addition of lysoplasmenylethanolamine (10-80 microM) to a crude membrane preparation of prelabeled platelets (0.24 mg of protein/ml) induces transfer of [3H]arachidonate from endogenous phosphatidylcholine to lysoplasmenylethanolamine (0.8 nmol of arachidonic acid/min/mg of protein). The transacylation reaction occurs in the absence of Ca2+, has a broad pH optimum from 7 to 8, is not affected by excess unlabeled arachidonic acid, and is inhibited by N-ethylmaleimide (0.2 mM) and Triton X-100 (0.1 mg/ml). The enzyme shows a high specificity toward the acyl donor (phosphatidylcholine), transfers fatty acids in the order: arachidonic greater than eicosatrienoic greater than oleic, and preferentially acylates lysoplasmenylethanolamine but also other lysophosphatides (lysophosphatidylethanolamine greater than lysophosphatidylserine greater than lysophosphatidylinositol = 0). Platelet acyltransferase, on the other hand, acylates ethanolamine lysophosphatides with free arachidonic acid in the order: lysophosphatidyl-ethanolamine greater than lysoplasmenylethanolamine. These results suggest that a distinct acylation mechanism exists for introduction of arachidonic acid into plasmalogen phosphatides. In stimulated platelets, the transacylase may play an additional role in the controlled release of esterified arachidonic acid for synthesis of the biologically active oxygenated metabolites.

Acyltransferases↗
PubMed1994

Genetic evidence supporting the role of peroxisome assembly factor (PAF)-1 in peroxisome biogenesis. Polymerase chain reaction detection of a missense mutation in PAF-1 of Chinese hamster ovary cells.

The peroxisome/plasmalogen-deficient Chinese hamster ovary (CHO) mutant cell line ZR-78.1 contains a missense mutation in its cDNA-encoding peroxisome assembly factor-1 (PAF-1). Using a rapid polymerase chain reaction assay, we now demonstrate that the genome of ZR-78.1 contains only the mutant allele. When mutant ZR-78.1 is fused with wild-type karyoplasts, occasional "negative nuclear hybrids" are observed that lack peroxisomes (Allen, L.-A. H., Morand, O. H., and Raetz, C. R. H. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 7012-7016). Despite the fact that negative nuclear hybrids are tetraploid, they do not contain the wild-type PAF-1 gene, suggesting that a chromosome fragment bearing the wild-type copy of PAF-1 was lost. Negative nuclear hybrids reconstituted with wild-type cytoplasts do contain a wild-type PAF-1 gene, indicating that the cytoplasts somehow reintroduced the wild-type PAF-1 allele without increasing ploidy. These findings support the role of PAF-1 and exclude the hypothesis of an additional cytoplasmic requirement for reinitiation of peroxisome biogenesis in peroxisome-deficient CHO cells. The plasmalogen deficiency and some other biochemical properties of ZR-78.1 are partially corrected in 5-azacytidine-treated subclones. However, such pseudo-revertants do not contain peroxisomes, consistent with the fact that there is no wild-type PAF-1 gene to reactivate by demethylation.

Acyltransferases↗
PubMed1993

[Zellweger syndrome, neonatal adrenoleukodystrophy or infantile Refsum's disease in a case with generalized peroxisome defect?].

An eleven month-old boy presented clinically with craniofacial dysmorphia, severe psychomotor retardation, neurological deterioration, no response to visual and acoustic stimuli, failure to thrive, hepatomegaly and adrenal insufficiency. Specific biochemical markers for a peroxisomal deficiency disorder (Zellweger's syndrome, neonatal adrenoleukodystrophy, infantile Refsum's disease) revealed pathological results for very long chain fatty acids, phytanic acid, pristanic acid, plasmalogen biosynthesis and catalase, thus confirming the clinical diagnosis. Comparison of clinical and biochemical findings in the patient with the characteristics of the three peroxisomal deficiency disorders showed overlapping with each of these disorders, which corresponds to the current view that these three peroxisomal disorders differ only with respect to onset and severity of the clinical manifestations, but not with regard to the biochemical defects.

Adrenoleukodystrophy↗
PubMed1998

Metabolic fate of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) and lyso-PAF (1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine) in FRTL5 cells.

The metabolism of platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) and lyso-PAF (1-O-alkyl-2-lyso-sn-glycero-3-phosphocholine) was investigated in FRTL5 cells, a normal rat thyroid cell line. FRTL5 cells incorporated [3H]PAF and deacetylated this compound to the corresponding [3H]lyso-PAF which was not accumulated or secreted but converted mainly to alkyl-acyl-phosphocholine indicating that this acylation process was particularly active in these cells. Among metabolic products of both [3H]PAF and [3H]lyso-PAF were alkylglycerol as well as its mono- and diacyl derivatives. [3H]alkylglycerol could be the intermediate compound for the production of [3H]alkyl- and [3H]alkenyl-phosphoethanolamine (plasmalogen) which were also metabolic products. FRTL5 cells were able to convert lyso-PAF to PAF especially when they were stimulated by ionophore A23187 in the presence of [3H]Iyso-PAF and phenylmethylsulfonyl fluoride. The amount of PAF increased for the first 30 min and declined thereafter. PAF resting levels were found low in the same cells. Furthermore, PAF-acetylhydrolase activity was determined in cell homogenates. The presence of metabolic products such as alkyl-phosphatidylcholine, alkyl- and alkenyl-phosphatidylethanolamine and alkyl-glycerol, as well as, its mono- and diacyl derivatives, indicates that FRTL5 cells and probably other thyroid cells, are very active in metabolizing PAF and lyso-PAF and suggests the co-operation of the corresponding metabolic pathways in these cells.

Acetylation↗