Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PLASMALOGEN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources

Effect of the antiprotozoal agent metronidazole (Flagyl) on absorptive and digestive functions of the rat intestine.

Metronidazole (Flagyl), an antibiotic commonly used in treating intestinal infections, when administered orally at a dose level of 100 mg/kg body weight daily for 7 days to rats brought about a significant elevation of the uptake of end-product nutrients like D-glucose, L-alanine, L-aspartic acid and L-leucine in the intestinal segments. Brush border membrane-bound hydrolytic enzymes, i.e. sucrase, lactase, maltase, alkaline phosphatase and leucine aminopeptidase levels, were also elevated. Substrate kinetic analysis of the uptake of nutrients as well as the enzymes indicated that the drug increased the maximum of apparent initial velocity, while the substrate affinity constants did not change. Studies of the temperature-dependent parameters of the nutrient uptake and the enzyme activity revealed that metronidazole did not induce any shift in the transition temperature (T(o)) for the uptake but the energy of activation (Ea) was reduced in all the cases except those of maltase and leucine aminopeptidase, which registered an increase in Ea and a marginal shift in T(o), respectively. A significant elevation was seen in the levels of membrane cholesterol, phospholipid, ganglioside and plasmalogen in metronidazole-treated animals, while triglycerides and the non-esterified fatty acids remained unaffected. The effects produced by metronidazole treatment persisted in the animals, which were allowed a recovery period of 7 days after the drug regimen.

Administration, Oral↗

X-linked dominant chondrodysplasia punctata with decreased dihydroxyacetone phosphate acyltransferase activity.

BACKGROUND: We examined an 18-month-old girl with typical clinical features of X-linked dominant chondrodysplasia punctata (CDPX2) with decreased activity of dihydroxyacetone phosphate acyltransferase (DHAP-AT), previously reported in CDPX2. On the other hand, steroid sulfatase, whose activity is deficient or decreased in X-linked ichthyosis and X-linked recessive chondrodysplasia punctata, has been reported to be normal in CDPX2, although all of these diseases have ichthyotic skin changes. OBJECTIVE: We measured the activity of DHAP-AT and steroid sulfatase of the patients fibroblasts to confirm the DHAP-AT abnormality in CDPX2. RESULTS: The DHAP-AT activity was remarkably reduced, but steroid sulfatase activity was within normal levels when compared with those of 2 healthy controls. CONCLUSION: The abnormal metabolism in plasmalogen synthesis in CDPX2 was confirmed. It is, however, unknown how the decreased DHAP-AT activity is related to the skin changes.

Acyltransferases↗

Phospholipids in meibomian gland secretion.

The bulk of the lipid layer overlying the aqueous portion of the precorneal tear film is composed of polar and nonpolar components. The nonpolar lipids have been the subject of numerous studies; however, the polar lipids have remained relatively uncharacterized. The polar lipids are thought to contain surfactant phospholipids that are critical to the spreading of a lipid film over the aqueous layer, by providing an interface between this layer and the nonpolar lipids. The purpose of the present study is to identify and quantitate the phospholipid complement of meibomian gland secretion which provides the tear film with phospholipids. Meibomian gland secretion was collected from rabbits and phospholipids identified and quantitated by 31P nuclear magnetic resonance spectroscopy. Ten phospholipids were detected from meibomian gland secretion: diphosphatidylglycerol, dihydrosphingomyelin, ethanolamine plasmalogen, phosphatidylethanolamine (PE), phosphatidylserine, sphingomyelin, lysophosphatidylcholine, phosphatidylinositol, alkylacylphosphatidylcholine, and phosphatidylcholine (PC). The two major phospholipids were PC and PE, together comprising nearly 60% of the total phospholipid profile. The nature and relative concentrations of the meibomian gland secretion phospholipids are congruous with a surfactant role at the aqueous-lipid interface and, considering the physical chemistry of the tear film, suggest that the phospholipids should be organized in a very flat or planar configuration.

Animals↗

The mobilization of arachidonic acid in platelets exposed to thrombin or ionophore A23187. Effects of adenosine triphosphate deprivation.

In studies conducted with human gel-filtered platelets, we have found: (a) that the release of serotonin and transfer of [3H]arachidonic acid from phosphatidylcholine and phosphatidylinositol to plasmalogen phosphatidylethanolamine which are associated with the activation of platelets by thrombin are both strongly dependent upon the presence of metabolic ATP; (b) that serotonin release and arachidonic acid mobilization in labeled phosphatides are promoted by the calcium ionophore A-23187 in media free of calcium ions; (c) that inhibitors of ATP synthesis, while leading to impairment of the release reaction induced by ionophore, do not inhibit ionophore-stimulated mobilization of arachidonic acid. We conclude that the activation of phospholipase A2 responsible for freeing arachidonic acid from platelet phosphatides is solely dependent upon the increased cytoplasmic levels of calcium ions promoted by either ionophore or, in an energy-dependent fashion by thrombin. Phospholipase activation is not a function of latent hydrolytic activity made available by the release reaction.

Adenosine Triphosphate↗

Platelet-activating factor: mediator of the third pathway of platelet aggregation? A study in three patients with deficient platelet-activating factor synthesis.

Thrombin, collagen, and Ca2+-ionophore A23187 aggregate platelets in the presence of inhibitors of the first (ADP-mediated) and second (cyclooxygenase-dependent) pathway of platelet activation. This aggregation, via a third pathway, was hypothesized to be mediated by the alkoxyether lipid platelet-activating factor (PAF). We recently demonstrated virtual absence of plasmalogen-type alkoxyether lipids and deficiency in key enzymes of their biosynthesis in Zellweger patients. We hypothesized that PAF synthesis might also be impaired. We report two Zellweger patients with an undetectable A23187-induced PAF synthesis of leukocytes (patients, less than 3 pmol PAF/10(8) granulocytes (PMN); four age-matched controls, 249-2,757 pmol PAF/10(8) PMN; five adult controls, 291-5,433 pmol PAF/10(8) PMN). In a third patient, residual PAF synthesis was detected. However in all patients the thrombin-induced third mechanism of platelet aggregation was present. We therefore conclude that PAF may not be the mediator of the third pathway.

Abnormalities, Multiple↗

Peroxisomal bifunctional enzyme deficiency.

Peroxisomal function was evaluated in a male infant with clinical features of neonatal adrenoleukodystrophy. Very long chain fatty acid levels were elevated in both plasma and fibroblasts, and beta-oxidation of very long chain fatty acids in cultured fibroblasts was significantly impaired. Although the level of the bile acid intermediate trihydroxycoprostanoic acid was slightly elevated in plasma, phytanic acid and L-pipecolic acid levels were normal, as was plasmalogen synthesis in cultured fibroblasts. The latter three parameters distinguish this case from classical neonatal adrenoleukodystrophy. In addition, electron microscopy and catalase subcellular distribution studies revealed that, in contrast to neonatal adrenoleukodystrophy, peroxisomes were present in the patient's tissues. Immunoblot studies of peroxisomal beta-oxidation enzymes revealed that the bifunctional enzyme (enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase) was deficient in postmortem liver samples, whereas acyl-CoA oxidase and the mature form of beta-ketothiolase were present. Density gradient centrifugation of fibroblast homogenates confirmed that intact peroxisomes were present. Immunoblots of fibroblasts peroxisomal fractions showed that they contained acyl-CoA oxidase and beta-ketothiolase, but bifunctional enzyme was not detected. Northern analysis, however, revealed that mRNA coding for the bifunctional enzyme was present in the patient's fibroblasts. These results indicate that the primary biochemical defect in this patient is a deficiency of peroxisomal bifunctional enzyme. It is of interest that the phenotype of this patient resembled neonatal adrenoleukodystrophy and would not have been distinguished from this disorder by clinical study alone.

3-Hydroxyacyl CoA Dehydrogenases↗

Diagnosis and follow-up of a case of peroxisomal disorder with peroxisomal mosaicism.

Peroxisomal disorder phenotypes are the result of mutations that cause defective peroxisomal assembly or alterations in the import mechanism of peroxisomal proteins that lead to multiple peroxisomal dysfunctions, or the result of a peroxisomal enzymatic deficiency with a single peroxisomal dysfunction. With complementation analysis, 16 groups have been found. Assignment of the genetic defect has been described for some of the complementation groups. We describe the clinical evolution and follow-up over 10 years of a patient who belongs to complementation group 4, although he showed a milder clinical course. It has been found in fibroblasts different peroxisome populations, normal processing and expression of beta-oxidation PTS1 and PTS2 proteins, abnormal ALD protein distribution and normal plasmalogen biosynthesis; abnormal beta-oxidation metabolites have also been detected in serum. Ultrastructural studies in liver showed peroxisomal mosaicism as in fibroblasts. It has been taken into account that peroxisomal mosaicism may lead to variability in peroxisomal diagnostic parameters, making difficult the final diagnosis in these patients.

Adolescent↗

Formation of multilamellar vesicles by addition of tannic acid to phosphatidylcholine-containing small unilamellar vesicles.

Tannic acid induces aggregation and formation of multilamellar vesicles when added to preparations of small unilamellar vesicles, specifically those containing phosphatidylcholine. Aggregation and clustering of vesicles was demonstrated by cryo-electron microscopy of thin films and by freeze-fracture technique. Turbidity measurements revealed an approximately one-to-one molar ratio between tannic acid and phosphatidylcholine necessary for a fast and massive aggregation of the small unilamellar vesicles. When tannic acid-induced aggregates were dehydrated and embedded for conventional thin-section electron microscopy, multilamellar vesicles were retrieved in thin sections. It is concluded from morphological studies, as well as previous tracer studies, that tannic acid, at least to a great extent, prevents the extraction of phosphatidylcholine. Multilamellar vesicles were also observed in tannic acid-treated vesicles prepared from total lipid extracts from either rabbit or rat hearts. Substantially more multilamellar vesicles were retrieved in the rabbit vesicle preparation. This difference can probably be explained by the difference in the proportion of the plasmalogen phosphatidylcholine, and possibly the content of sphingomyelin, in lipid extracts of rabbit and rat hearts. It is concluded that the dual effect (reduced extraction and aggregation) of tannic acid on phosphatidylcholines should be taken into consideration when tannic acid is used in tissue preparation.

Animals↗

Analysis of cell membrane aminophospholipids as isotope-tagged derivatives.

Glycerophosphoethanolamine (GPEtn) and glycerophosphoserine (GPSer) lipids were reacted with a multiplexed set of differentially isotopically enriched N-methylpiperazine acetic acid N-hydroxysuccinimide ester reagents, which place isobaric mass labels at a primary amino group. The resulting derivatized aminophospholipids were isobaric and chromatographically indistinguishable but yielded positive reporter ions (m/z 114 or 117) after collisional activation that could be used to identify and quantify individual members of the multiplex set. The chromatographic and mass spectrometric response of N-methylpiperazine amide-tagged aminophospholipids was probed using glycerophosphoethanolamine and glycerophosphoserine lipid standards. The [M+H]+ of each tagged aminophospholipid shifted 144 Da, and during collision-induced dissociation the major fragmentation ion was either m/z 114 or 117. This mode of detecting aminophospholipids was useful for an unbiased analysis of plasmalogen GPEtn lipids. Molecular species information on the esterified fatty acyl substituents was obtained by collisional activation of the [M-H]- ions. The isotope-tagged reagents were used to assess changes in the distribution of GPEtn lipids after exposure of liposomes made from phospholipids extracted from RAW 264.7 cells to Cu2+/H2O2 to illustrate the ability of these reagents to aid in the mass spectrometric identification of aminophospholipid changes that occur during biological stimuli.

Animals↗

Synthesis and biological properties of the fluorescent ether lipid precursor 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol.

The synthesis of an omega-pyrene-labeled 1-O-alkyl-sn-glycerol was performed using a chirospecific method starting from R-(-)-2,3-O-isopropylidene-sn-glycerol. The product, 1-O-[9'-(1''-pyrenyl)]nonyl-sn-glycerol (pAG), is a fluorescent ether lipid that has a pyrene moiety covalently attached at the alkyl chain terminus. pAG was taken into CHO-K1 cells and a plasmalogen-deficient variant of CHO-K1, NRel-4. This variant is defective in dihydroxyacetonephosphate acyltransferase, which catalyzes the first step in plasmenylethanolamine (PlsEtn) biosynthesis. pAG was incorporated primarily into ethanolamine and choline phospholipids as well as a neutral lipid fraction tentatively identified as alkyldiacylglycerol. NRel-4 accumulated more fluorescence in the phospholipid fraction than CHO-K1, specifically in the ethanolamine phospholipids. Analysis of the fluorescent lipids showed that 93% of the pAG was incorporated into glycerolipids with the ether bond intact. Although the addition of 20 microM 1-O-hexadecyl-sn-glycerol to the medium fully restored PlsEtn biosynthesis in NRel-4 cells, pAG only partially restored PlsEtn synthesis. Incubation of cells with pAG followed by irradiation with long-wavelength (>300 nm) ultraviolet light resulted in cytotoxicity. NRel-4 cells displayed an increased sensitivity to this treatment compared with CHO-K1 cells. This photodynamic cytotoxicity approach could be used to select for mutants that are defective in downstream steps in ether lipid biosynthesis.

Animals↗

Zellweger syndrome: biochemical and morphological studies on two patients treated with clofibrate.

Two infants with Zellweger syndrome (cerebro-hepato-renal syndrome) have been studied biochemically and morphologically. Peroxisomal enzymes involved in respiration, fatty acid beta-oxidation, and plasmalogen biosynthesis were assessed. In liver, catalase was present in normal amounts but was located in the cell cytosol. Dihydroxyacetone phosphate acyltransferase activity was less than one-tenth of normal. The amount of the bifunctional protein catalyzing two beta-oxidation reactions was found by immunoblotting to be greatly reduced. Catalase activity was normal in intestine. D-Amino acid oxidase was subnormal in kidney. The observed enzyme deficiencies may plausibly explain many of the metabolite imbalances observed clinically. Morphologically, peroxisomes were absent from liver. In intestine, normal peroxisomes were also missing, but some rare, smaller (0.04-0.13 micrometer) bodies were seen with a slight positive cytochemical reaction for catalase. These results, together with current concepts of peroxisome biogenesis, suggest but do not prove, that the primary defect in Zellweger syndrome may be in peroxisome assembly. The infants were treated with clofibrate, but it was ineffectual as assessed biochemically, morphologically, and clinically.

Abnormalities, Multiple↗

Genetic and phenotypic heterogeneity in disorders of peroxisome biogenesis--a complementation study involving cell lines from 19 patients.

Disorders of peroxisomal biogenesis include the Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum syndrome, and hyperpipecolic acidemia. These names were assigned before the recognition of the peroxisomal defect and the distinction between phenotypes is uncertain. Recent studies have identified at least four complementation groups, and indicate the presence of at least that number of distinct genotypes. The purpose of the present study was to examine the relationship between genotype and phenotype. We studied cultured skin fibroblasts from 19 patients in whom deficiency of peroxisomes had been established. Complementation analysis was performed with the criterion of complementation being the restoration of the capacity to synthesize plasmalogens when fibroblasts from two patients were fused. Six complementation groups were identified, and consisted of one 13 member group, one two member group, and four groups comprising single cases. The phenotype of each group was examined with respect to age of survival, clinical manifestations, and biochemical alterations. The 13 member group included patients with all of the four currently designated phenotypic entities, while the most common phenotype (Zellweger syndrome) was distributed among five of the six groups. We conclude that the currently used clinical categories do not represent distinct genotypes. Apparently different genes code for a similar phenotype and one defective gene may lead to variant phenotypes. Definitive classification and understanding of these disorders await definition of the specific biochemical defect in each of the genotypes.

Adrenoleukodystrophy↗

Aberrant subcellular localization of peroxisomal 3-ketoacyl-CoA thiolase in the Zellweger syndrome and rhizomelic chondrodysplasia punctata.

Fibroblasts from patients with the inherited disorder Zellweger syndrome have few or no peroxisomes; multiple biochemical processes that normally occur in this organelle are defective. Rhizomelic chondrodysplasia punctata (RCDP) is another inherited disorder in which two unrelated peroxisomal metabolic processes, plasmalogen synthesis and phytanic acid oxidation, are impaired despite the normal appearance of peroxisomal structure. It was previously reported that one of the enzymes of peroxisomal fatty acid beta-oxidation, 3-ketoacyl-CoA thiolase (beta-keto-thiolase), was present in precursor rather than mature form in both of these diseases. Immunofluorescent staining for peroxisomal beta-ketothiolase showed the immunoreactivity to be localized in subcellular particles in fibroblasts from both Zellweger syndrome and RCDP patients, even though the former lack normal peroxisomes. Immunoblot studies were performed to determine the subcellular location of the thiolase precursor in fractionated fibroblasts from Zellweger and RCDP patients. In both disorders, thiolase immunoreactivity was detected in subcellular fractions having a lower density than normal peroxisomes and mitochondria, and was resistant to digestion by proteinase K. The density of the thiolase precursor-containing fractions was similar to that of peroxisomal membrane "ghost" fractions recently described by Santos et al. (J Biol Chem 263:10502-10509, 1988). Our results suggest that these are not empty membrane vesicles but contain at least one peroxisomal matrix protein. Furthermore, they exist not only in cells in which normal peroxisomes fail to form (Zellweger syndrome), but also in some cells which have catalase-containing peroxisomes (RCDP).

Acetyl-CoA C-Acyltransferase↗

Correction by gene expression of biochemical abnormalities in fibroblasts from Zellweger patients.

Zellweger syndrome is a prototype of peroxisomal biogenesis disorders and a fatal autosomal recessive disease with no effective therapy. We identified nine genetic complementation groups of these disorders, and mutations in peroxisome assembly factor-1 (PAF-1) and the 70-kD peroxisomal membrane protein (PMP70) genes have been detected by our group F and Roscher's group 1, respectively. We now describe permanent recovery from generalized peroxisomal abnormalities in fibroblasts of a Zellweger patient from group F, such as biochemical defects of peroxisomal beta-oxidation, plasmalogen biosynthesis, and morphologic absence of peroxisomes, by stable transfection of human cDNA encoding PAF-1. In the light of these observations, we designed a gene expression system using fibroblasts from patients with peroxisomal biogenesis disorders. In Zellweger fibroblasts obtained from Roscher's group 1 and transfected with human cDNA encoding PMP70, peroxisomes were not morphologically identifiable, and peroxisomal function did not normalize.

ATP-Binding Cassette Transporters↗

Natural alkylglycerols restrain growth and metastasis of grafted tumors in mice.

Alkylglycerols are natural etherlipids abundant in shark liver oil (SLO) in a diacylated form. SLO is known to have antitumor properties and was recently described as an inhibitor of tumor neovascularization. However, most studies did not discriminate between the respective activities of alkylglycerols and of fatty acids, which both have potent biological properties. In this work, a mouse model was used to investigate the antitumor effects of SLO and of alkylglycerols purified from the same source, both administered orally. We demonstrated that either pure alkylglycerols or SLO reduced the tumor growth in a similar manner, suggesting that alkylglycerols were involved in this effect. In alkylglycerol-treated mice, metastasis dissemination was reduced by 64 +/- 8%, whereas SLO effect was 30 +/- 9% below control. Purified alkylglycerols also decreased significantly plasmalogen content in tumors, whereas SLO had no such effect. Finally, we demonstrated that a 5-day treatment with alkylglycerols curtailed the presence in tumors of von Willebrand factor, a marker of endothelial cells. This result suggested an anti-angiogenic effect of alkylglycerols. In summary, alkylglycerols were shown to decrease the growth, vascularization, and dissemination of Lewis lung carcinoma tumors in mice. These findings suggest that the antitumor activity of SLO is likely mediated by the presence of alkylglycerols.

Angiogenesis Inhibitors↗

Glucocorticoid effects on lipid metabolism in HeLa cells: inhibition of cholesterol synthesis and increased sphingomyelin synthesis.

Glucocorticoid treatment had a variety of effects on lipid composition of HeLa S3G (HeLa 65) cells. Total cellular cholesterol levels were lower in treated cultures than in controls within 6 h of the addition of glucocorticoids and remained lower for up to 48 h. Total cell protein and total lipid phosphorus levels were also decreased, but only after more prolonged exposure. The major phospholipid components, viz. phosphatidylcholine and phosphatidylethanolamine, representing, respectively, 48% and 29% of the total phospholipids, were not affected by glucocorticoid treatment. Sphingomyelin, however, increased from 4.8 to 8.3% of the total phospholipid content after 48 h of exposure, whereas lysolecithin increased from 0.1 to 1.9%. The incorporation of labeled precursors was also measured after glucocorticoid addition. As related to cellular protein content, only slight increases were found for all major phospholipids. In contrast, sphingomyelin synthesis increased up to 200% after treatment with glucocorticoids. The fatty acid and plasmalogen compositions were unchanged by glucocorticoids.

Cholesterol↗

Gonadotropin-releasing hormone stimulates phospholipid labeling in cultured granulosa cells.

Cultured ovarian granulosa cells from preantral and preovulatory follicles were incubated with [32P]Pi to label endogenous phospholipids. Labeled cells were then incubated with FSH, GnRH, or a GnRH agonist analog [D-Ala6]GnRH (GnRHa), cellular phospholipids were separated by two-dimensional thin layer chromatography, and the radioactivity was determined. Phosphatidylcholine was the major labeled phospholipid accounting for 64% of the total radioactivity. The remaining labeling was distributed among choline plasmalogen (8.4%), phosphatidylinositol (6.3%), lyso phosphatidylcholine (3.7%), phosphatidylethanolamine (3.4%), phosphatidic acid (1.75%), phosphatidylserine (1.65%), and cardiolipin (1.3%). GnRH and its agonist analog GnRHa, but not FSH, increased 32P incorporation into phospholipids by 2-fold. Analysis of the several phospholipids revealed that GnRHa (10(-7) M) increased 32P labeling of phosphatidylcholine and lyso phosphatidylcholine by 1.5- and 2.5-fold respectively, and that of phosphatidic acid and phosphatidylinositol by 5- and 7-fold, respectively, during 60 min of incubation. The natural decapeptide GnRH was 30 times less potent than its agonist analog. Labeling of other phospholipids was not affected by GnRHa treatment, and FSH had no effect on 32P incorporation under similar conditions. The stimulatory effect of GnRHa was blocked by the potent GnRH antagonist [D-pGlu1,pClPhe2, D-Trp3,6]GnRH. The minimal stimulating dose of GnRHa was 10(-12) M, and increased phospholipid labeling could be detected after 10 min of incubation with the analog. These results indicate that phospholipids, in particular phosphatidylinositol and phosphatidic acid, might be involved in the mechanism by which GnRH exerts its gonadal effects.

Animals↗

MRI evidence that docosahexaenoic acid ethyl ester improves myelination in generalized peroxisomal disorders.

OBJECTIVE: We have found that docosahexaenoic acid (DHA; 22:6n-3), an important constituent of the CNS and retina, is dramatically decreased in patients with generalized peroxisomal disorders. Such a DHA deficiency could be pathogenic. Our aim was to test the possible beneficial effects of normalizing the DHA levels in these patients. The current report focuses on MRI changes during the treatment and reports follow-up evidence of myelin improvement in five peroxisomal disorder patients treated with DHA. METHODS: DHA ethyl ester (DHA-EE), about 90% pure, was used at daily oral doses of 100 to 600 mg. The treatment was monitored both clinically and biochemically, with periodic neurophysiologic and MRI examinations and repeated controls of liver tests and blood fatty acids by capillary column gas chromatography. RESULTS: DHA-EE normalized the blood levels of DHA in a few weeks. The levels of very-long-chain fatty acids decreased in plasma and those of plasmalogens increased in erythrocytes. Visual and liver function improved. On MRI, a virtual normalization of the brain myelin images was found in the three youngest patients. A clear improvement was noticed in the other two. CONCLUSIONS: The beneficial effects obtained indicate that DHA deficiency plays an important role in the pathogenesis of peroxisomal disease, probably in relation to myelinogenesis. Early initiation of DHA therapy is thus strongly recommended in patients with generalized peroxisomal disorders.

Brain Diseases↗