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Results 451 - 500 of 1228
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Tóth M - - 1993
Metabolic conversion of the synthetic DAG, dioctanoylglycerol (DOCG) into the dioctanoyl species of phosphatidic acid (PADOCG) and phosphatidylcholine (PCDOCG) in minced human primordial placenta incubated with [32P]phosphate was studied. Time-course experiments performed with 0.25 mM DOCG revealed a much higher capacity of the placenta to synthetize PCDOCG than PADOCG and ...
Duclos R I RI - - 1993
A general method for the chirospecific synthesis of 1-acyl-2-alkyl-sn-glycero-3-phosphocholines is described. 1-Palmitoyl-2-hexadecyl-sn-glycero-3-phosphocholine (PHPC) was synthesized in 18% overall yield in ten steps via five new synthetic intermediates, and 1-acetyl-2-hexadecyl-sn-glycero-3- phosphocholine (AHPC) was also synthesized. 1-Acyl-2-alkyl-sn-glycero-3-phosphocholines, which have not been found to exist in nature, are ether lipid analogs of 1,2-diacyl-sn-glycero-3-phosphocholines, ...
Nevalainen T J - - 1993
Phospholipase A2 (EC 3.1.1.4; PLA2) is detected in serum by determination of either the catalytic activity of the enzyme or the concentration of the enzyme protein by immunoassays. The most sensitive methods for determining PLA2 catalytic activity are radiometric assays, with a substrate of synthetic phospholipid (e.g., phosphatidylcholine or phosphatidylethanolamine) ...
Jacob G - - 1993
1. Phospholipase C activity present in the membranes of Xenopus laevis oocytes has been studied. 2. These membranes contain an activity capable of hydrolyzing phosphatidylinositol, phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate. 3. Hydrolysis of PtdIns 4,5-P2 is absolutely dependent on the presence of Ca2+, however, the hydrolysis of PtdIns occurs in ...
Green P - - 1993
Tracer amounts of either [1-14C]linolenic (18:3n-3, LNA), or [1-14C]linoleic (18:2n-6, LA) acids were intracranially injected into 19- to 20-day-old rat fetuses, and the time course of the in vivo formation and esterification of their long chain polyenoic metabolites was determined for up to 20 h. A rapid disappearance of free ...
Qualliotine-Mann D - - 1993
NADPH oxidase, the respiratory burst enzyme of human neutrophils, is a multi-component complex that is assembled and activated during stimulation of the cells by inflammatory or phagocytic stimuli. The signal mechanisms leading to activation of the enzyme are unclear, but it is likely that phospholipases are involved. Recent work has ...
McPhail L C - - 1993
The signal transductional mechanisms regulating the activation of NADPH oxidase, the respiratory burst enzyme in phagocytic cells, are not completely understood. Receptors for most physiologic stimuli trigger the activation of various phospholipases, including phospholipases A2, C, and D. The lipid mediators formed (arachidonic acid, 1,2-diacylglycerol, and phosphatidic acid) have been ...
Katsura K - - 1993
The objective of the present experiments was to correlate changes in cellular energy metabolism, dissipative ion fluxes, and lipolysis during the first 90 s of ischemia and, hence, to establish whether phospholipase A2 or phospholipase C is responsible for the early accumulation of phospholipid hydrolysis products. Ischemia was induced for ...
Aufenanger J - - 1993
Phospholipase A2 activity in human sera was determined of the basis of the E. coli assay and compared to a photometric micelle assay. The E. coli assay is based on the hydrolysis of phospholipids from [1-14C]oleic acid-labelled E. coli biomembranes. In the photometric assay the phospholipase A2 acts on mixed ...
Kreps D M - - 1993
Pretreatment of 1321N1 human astrocytoma cells with serum induces a pronounced increase in subsequent stimulation by forskolin and other agents of intracellular cyclic AMP accumulation, a phenomenon referred to as sensitization (Mol. Pharmacol. 39, 399-406, 1991). Pretreatment of these cells with lysophosphatidic acid induced sensitization to a similar extent as ...
Endresen M J - - 1993
Sera from pre-eclamptic women exhibit an increased lipolytic activity compared to sera of women with normal pregnancies. The null hypothesis of this study was that the increased release of free fatty acids (FFA) was due to hydrolysis of circulating triglycerides. The nature of the increased lipolytic activity was investigated by ...
Jones G A - - 1993
A survey of lipids revealed that the anionic phospholipid phosphatidic acid activates both control and tyrosine-phosphorylated PLC-gamma 1. The mechanism by which phosphatidic acid activates both forms of PLC-gamma 1 was investigated using kinetic analysis. In the presence of phosphatidic acid, the substrate concentration response for control PLC-gamma 1 changes ...
Tamura M - - 1993
The ability of phosphatidic acid to induce O2- generation was examined in intact and electropermeabilized neutrophils. In intact cells, after a long lag (approximately 11 min), 1,2-didecanoylphosphatidic acid (PA10, 10 microM) elicited O2- generation (30-40 nmol/min/10(7) cells at maximum) which lasted for 8-9 min. Electropermeabilization facilitated the response by shortening ...
Skorve J - - 1993
The modulation of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) biosynthesis by sulfur-substituted fatty acid analogues has been investigated in rats. We have compared the effects of two non-beta-oxidizable fatty acid analogues, 3-thiadicarboxylic acid and tetradecylthioacetic acid, which induce proliferation of peroxisomes, with those of the analogue tetradecylthiopropionic acid, which is a ...
Miller R R RR - - 1993
When administered in the diet to third instar Drosophila melanogaster larvae, short chain primary alcohols reduce phosphatidylcholine (PC) levels. The ethanol-induced reductions in larval PC may be in part due to an increase in the activity of PC-specific phospholipase D (PC-specific PLD, EC 3.1.4.4). PC-specific PLD not only hydrolyzes PC, ...
Ohishi H - - 1993
To improve our understanding of why phospholipase A2 (PLA2) specifically catalyzes the hydrolysis of the fatty acid ester bond at position 2, not at position 1, of 1,2-diacyl-3-sn-phosphoglycerides, the binding of each fatty acid chain of 1,2-dilauroyl-L-phosphatidyl-ethanolamine (DLPE), a natural substrate, to bovine pancreas PLA2 was examined by molecular dynamics ...
Tronchère H - - 1993
The effect of phorbol 12-myristate 13-acetate (PMA) on [3H]choline incorporation into phosphatidylcholine (PtdCho) and on the 'de novo' pathway of PtdCho synthesis has been investigated, compared with that of oleic acid, in ascitic-strain Krebs-II cells. Both compounds stimulated [3H]choline incorporation into PtdCho, but the PMA-induced incorporation was saturable at concentrations ...
Budnik L T - - 1993
LH-stimulated adenylate cyclase activity in membrane preparations of bovine luteal cells could be enhanced by treating the cells with either phospholipase D or its hydrolysis product, phosphatidic acid. Similar augmentary effects were also produced following treatment of the cells with EGF. Moreover, EGF could stimulate the formation of [3H]phosphatidic acid ...
van Blitterswijk W J - - 1993
Generation and attenuation of lipid second messengers are key processes in cellular signalling. Receptor-mediated increase in 1,2-diacylglycerol (DG) levels is attenuated by DG kinase and DG lipase. We here report a novel mechanism of DG attenuation by phospholipase D (PLD), which also precludes the production of another (putative) second messenger, ...
Kikuchi-Yanoshita R - - 1993
Phospholipid-hydrolyzing activities were examined in rat hearts with ischemia induced by occlusion of the left main coronary artery. When homogenates of ischemic heart were incubated in vitro at 37 degrees C, a significant amount of phosphatidylethanolamine (PE) was degraded, whereas the contents of other phospholipids did not change significantly. During ...
Sunderland J E - - 1993
The transfer of long-chain anthroyloxy-labeled-free fatty acids (AOffa) between small unilamellar vesicles (SUV) was studied using a fluorescence energy transfer assay. Donor SUV were labeled with AOffa, and acceptor SUV contained the nonexchangeable quencher NBD-phosphatidylethanolamine. Donor and acceptor membranes were mixed using a stopped-flow apparatus, and intermembrane transfer was monitored ...
Merida I - - 1993
The biological effects of interleukin-2 (IL-2) were examined in T lymphocytes. IL-2 binding induced the rapid activation of diacylglycerol kinase in both cytosolic and membrane subfractions. This enzyme utilized diacylglycerol from multiple endogenous and exogenous sources for the synthesis of phosphatidic acid. Phosphatidic acid was, in turn, shown to stimulate ...
Lakin-Thomas P L - - 1993
An inositol-requiring strain of Neurospora crassa was labelled during growth in liquid medium with [3H]inositol, and the levels of inositol phosphates and phosphoinositides were determined under inositol-sufficient and inositol-starved conditions. Because the mutant has an absolute requirement for inositol, the total mass of inositol-containing compounds could be determined. Inositol-containing lipids ...
Portal I - - 1993
The purpose of this work was to evaluate biliary phosphatidylcholine (PC) secretion after intravenous infusion of high density lipoprotein (HDL)-[3H]phosphatidylcholine (HDL-[3H]PC) in rats and to study the effect of infusion of dehydrocholic and cholic acids, which, respectively, inhibit and stimulate biliary secretion of PC. The data obtained in this study ...
Fukuzawa K - - 1993
Peroxidation of egg yolk phosphatidylcholine (egg PC) liposomes was induced by addition of ascorbic acid (AsA) and Fe(II) in the presence of a trace of autoxidized egg PC (PC-OOH), but not in the absence of PC-OOH. PC-OOH was degraded upon addition of AsA and Fe(II) but not of either one ...
Mustonen P - - 1993
As revealed by resonance energy transfer utilizing pyrene-labeled phosphatidylcholine donor, the mainly electrostatically controlled binding of adriamycin (Adr) and cytochrome c (cyt c) to mixed egg yolk phosphatidic acid/phosphatidylcholine (eggPA/eggPC, 15:85 molar ratio) liposomes was reversed upon the inclusion of increasing contents of sphingosine. At a [sphingosine]/[eggPA] molar ratio of ...
Trotter P J - - 1993
The Caco-2 human intestinal cell line was used to examine fatty acid esterification during development of the enterocytic phenotype. Acyl-CoA synthetase activity increased approximately 40%, and the incorporation of palmitic acid into triacylglycerol relative to phosphatidylcholine increased nearly 2-fold during Caco-2 differentiation. A rate-limiting enzyme activity in the glycerol 3-phosphate ...
van den Berg J J - - 1993
Cleavage of oxidized fatty acids by phospholipase A2 has been implicated as the first step in the repair mechanism for oxidative damage to membrane phospholipids. However, the mechanism by which this enzyme preferentially hydrolyzes oxidized fatty acyl chains is poorly understood. Using a lipid monolayer technique, we found that the ...
Doering T L - - 1993
The trypanosome variant surface glycoprotein (VSG) is anchored to the outer leaflet of the parasite plasma membrane by a glycosyl phosphatidylinositol (GPI). The VSG anchor is unique among GPIs in containing exclusively dimyristoylglycerol as its lipid moiety. Myristate is incorporated into the anchor precursor by sequential deacylation and specific reacylation ...
Fanjul L F - - 1993
In the present investigation, a hCG sensitive glycosyl-phosphatidylinositol (GPI) was isolated from cultured rat granulosa cells obtained from the ovaries of diethylstilbestrol (DES) implanted immature rats. The inositol-phosphoglycan (IPG) moiety of the GPI-lipid contains galactose, glucosamine, and myoinositol as demonstrated by metabolic labelling of granulosa cells for different time periods ...
Püttmann M - - 1993
Phospholipase A (PLA) activities were measured by high-performance liquid chromatography in two enzyme preparations purified from human duodenal juice and a serum pool as well as in 52 sera from 31 intensive-care patients with various diseases. On the basis of a position-specific fatty acid analysis of the natural substrate ("soybean ...
Tojo H - - 1993
This paper appraises an HPLC method for assaying phospholipase A2 (PLA2). The procedure is based on heptane-isopropanol-H2SO4 extraction of fatty acids released by the enzyme in the presence of margaric acid as an internal standard, and precolumn derivatization with 9-anthryldiazomethane. The derivatives of naturally occurring long-chain fatty acids were accurately ...
Blokland A - - 1993
In the present study we evaluated a new method to assess the behavioural and biochemical effects of a brief period of acute hypoxia in the brain. In this method, cyanide is injected into the lateral ventricles. Spatial navigation performance in a Morris task was found to be impaired 1 and ...
Low M G - - 1993
Previous work has suggested that the glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) purified from bovine serum is inhibited by phosphatidic acid (PA). In this study we report on the specificity and mechanism of this phenomenon using [3H]myristate-labeled variant surface glycoprotein dispersed in Nonidet P-40 as substrate. Inhibition of GPI-PLD by PAs (IC50 ...
Pidgeon C - - 1993
Heteroatom fatty acid analogs of myristic acid containing oxygen or sulfur substituted for the alkyl methylene groups inhibit replication of the human immunodeficiency virus (HIV) in infected cells by acting as alternative substrates during the viral protein myristoylation event. In this class of compounds, 12-methoxydodecanoic acid is the most potent ...
Huterer S J - - 1993
Positional specificities in donor and acceptor phospholipids of the lysosomal phosphatidylcholine: bis(monoacylglycero)phosphate acyltransferase have been determined. Comparison of the transfer of labelled fatty acid from sn-1 [14C]acyl and sn-2 [14C]acylphosphatidylcholines by extracts of rat liver lysosomes revealed that fatty acids in the sn-1 position were exclusively transferred. Degradation of the ...
Vandenburgh H H - - 1993
Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E2 and F2 alpha which regulate protein turnover rates and muscle cell growth. These stretch-induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of ...
Bütikofer P - - 1993
We have studied the mechanism by which calcium-loading of human erythrocytes stimulates phospholipid turnover and generates diacylglycerol and phosphatidic acid. Using quantitative measurement of individual phospholipid classes, we have demonstrated that the amount of phosphatidic acid generated during calcium-loading of intact red cells exceeds the amount of diacylglycerol formed by ...
Marcoz P - - 1993
The role of phospholipid metabolites in the modulation of cyclic AMP degradation during the early response of rat thymic lymphocytes to mitogenic stimulation was investigated by measuring their in vitro effect on the activity of five different cyclic nucleotide phosphodiesterase forms separated from thymocyte cytosol by means of an HPLC ...
Negre-Aminou P - - 1993
We analyzed de novo synthesis and local turnover of phospholipids in the growing neuron and the isolated nerve growth cone. The metabolism of phosphatidylinositol (PI) was studied with regard to the incorporation of saturated and unsaturated fatty acids and inositol. A comparison of de novo phospholipid synthesis in the intact ...
Liepkalns V A - - 1993
Total lipid extracts were obtained from SH-SY5Y human neuroblastoma cells grown to confluency in mycoplasma-free 10% fetal calf serum. The major glycerophospholipid classes and free diacylglycerols (DAG) were isolated and quantitated by silicic acid and DEAE-cellulose column and thin-layer chromatography. The choline (CGPL), ethanolamine (EGPL), serine (SGPL), and inositol (IGPL) ...
Kurz T - - 1993
The cellular content of phosphatidic acid can increase in response to several agonists either by phosphorylation of diacylglycerol after phospholipase C-catalyzed hydrolysis of phospholipids or directly through activation of phospholipase D. Although previous findings indicated that the generation of phosphatidic acid was exclusively a means of regulation of the cellular ...
Bonventre J V - - 1993
Phospholipases A2 comprise a family of enzymes that hydrolyze the acyl bond at the sn-2 position of phospholipids to generate free fatty acids and lysophospholipids. In the central nervous system products of PLA2 regulate neurotransmission. In addition, the lysophospholipids, free fatty acids, eicosanoids, platelet activating factor and reactive oxygen species, ...
Raines D E - - 1993
The effect of salt and pH titration on the selectivity of spin-labeled analogues of phosphatidic acid, phosphatidylserine, phosphatidylcholine, and stearic acid for the nicotinic acetylcholine receptor (nAcChoR) reconstituted into dioleoylphosphatidylcholine was examined at 0 degrees C using electron spin resonance spectroscopy. The order of selectivity at pH 7.4 and 0 ...
Chiu T H - - 1993
A membrane enzyme preparation from Streptococcus sanguis was shown to convert sn-[14C]glycerol 3-phosphate and CDP-diacylglycerol (or deoxyCDP-diacylglycerol) into a series of progressively higher-molecular-weight [14C]oligophosphoglycerophospholipids in vitro. The first oligophosphoglycerophospholipid to accumulate (termed lipid-1) was purified to homogeneity; chemical analysis, gas-liquid chromatography and chemical degradation studies indicated the most likely structure ...
Burdge G C - - 1993
Hepatic phosphatidylcholine (PC) from the immature fetal guinea pig at day 55 of gestation comprised mainly unsaturated molecular species containing C18:2(n-6) and C22:6(n-3) at the sn-2 position, reflecting placental permeability to essential fatty acids. At both day 55 and term (day 68), [Me-14C]choline was incorporated in utero over 3 h ...
Carabaza A - - 1993
The effect on human herniated intervertebral disc phospholipase A2 (HD-PLA2) of a number of retinoids, antirheumatic drugs and reported PLA2 inhibitors was evaluated using autoclaved [1-14C]-oleate-labeled Escherichia coli membranes as the substrate. Dexamethasone, non-steroidal antiinflammatory drugs, aristolochic acid and retinol were inactive, whereas a marked inhibition was found for manoalide, ...
Zhang Y - - 1993
It is well established that production of prostaglandins by ocular tissues is dependent upon the species. The rabbit iris-ciliary body produces greater amounts of prostaglandins than that of the bovine. To throw more light on the biochemical basis underlying these differences we have compared the fatty acid composition and phospholipases ...
Senisterra G A - - 1993
Phosphatidic acid in the form of small unilamellar vesicles has a dissociation constant of about 8.3 as determined by 31P nuclear magnetic resonance (NMR) spectroscopy. The activation of protein kinase C (PKC) by monovalent phosphatidic acid or phosphatidylserine occurs only in the presence of Ca2+. However, PKC activity on membranes ...
Schödel F - - 1993
The hepatitis B virus core gene codes for two polypeptides: the core protein, which assembles to form particles (HBcAg), and the secreted precore protein (HBeAg). Expression vectors directing the synthesis in Escherichia coli of a recombinant HBeAg corresponding in sequence to serum-derived HBeAg encompassing the 10 precore amino acids remaining ...
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