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Results 401 - 450 of 1218
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Stettner S - - 1995
After betamethasone treatment, a significant diminution of the monoenoic phosphatidylcholine 32 carbon species (palmitoyl-palmitoleyl phosphatidylcholine and palmitoleyl-palmitoylphosphatidylcholine) and the phosphatidylcholine 34 carbon species (primarily palmitoyl-oleoyl-phosphatidylcholine) could be demonstrated both in absolute and relative terms, while the palmitic acid portion in the phosphatidylcholine fatty acids was nearly unchanged. This is consistent ...
Ye H - - 1994
OBJECTIVE: The aim was to assess whether noradrenaline and endothelin-1 can stimulate endogenous production of phosphatidic acid in adult ventricular myocytes. METHODS: After stimulation of rabbit ventricular myocytes with noradrenaline and endothelin-1, total lipids were extracted using the Bligh and Dyer procedure and separated by thin layer chromatography, and phosphatidic ...
Konrad R J - - 1994
Arachidonic acid has been implicated as a second messenger in insulin secretion on the basis of (1) mobilization of intracellular Ca2+ from the endoplasmic reticulum of islets and (2) amplification of voltage-dependent Ca2+ entry. The insulin secretagogues D-glucose and the muscarinic agonist carbachol both increase unesterified arachidonic acid accumulation in ...
Ahmad T - - 1994
The addition of exogenous oleic acid to erythrocyte membranes induces a characteristic membrane crenation and sensitises the cells to the lytic action of phospholipase A2 enzymes. Both effects are extremely sensitive to inhibition by endogenous lysophosphatidyl choline (LPC), but the strength of inhibition depends of the order in which the ...
Doering T L - - 1994
New drugs are needed for treatment of diseases caused by African trypanosomes. One possible target for chemotherapy is the biosynthesis of the glycosyl phosphatidyl-inositol (GPI) of this parasite's variant surface glycoprotein (VSG). Unlike mammalian GPIs, the diacylglycerol moiety of the VSG anchor contains only myristate (tetradecanoate), added in unique remodeling ...
Satouchi K - - 1994
A fairly large amount of lysophosphatidylcholine (LPC) was detected in the fresh muscle of bonito Euthynnus pelamis (Linnaeus). The major fatty acid esterified in LPC were highly unsaturated fatty acids, such as docosahexaenoic and eicosapentaenoic acids, and the form was mainly composed of 1-lyso-2-acyl-sn-glycero-3-phosphocholine (1-LPC). The content of this species ...
Higgs H N - - 1994
Recent experiments in several laboratories have provided evidence that phosphatidic acid functions in cell signaling. However, the mechanisms that regulate cellular phosphatidic acid levels remain obscure. Here we describe a soluble phospholipase A1 from bovine testis that preferentially hydrolyzes phosphatidic acid when assayed in Triton X-100 micelles. Moreover, the enzyme ...
Roldan E R - - 1994
In ram spermatozoa, treatment with the ionophore A23187 and Ca2+ led to an increase in total diacylglycerol mass and to exocytosis of the acrosomal granule. If sperm cells were prelabeled with [3H]palmitic acid, stimulation with A23187/Ca2+ resulted in the generation of [3H]diacylglycerols with a mixture of saturated and unsaturated fatty ...
Schole J - - 1994
20 min after intraportal infusion of diethyl phosphate (DEP) in rats, the mitochondrial cardiolipin (CL; 1,3-bisphosphatidyl glycerol) fraction is labelled with DEP. The obtained mixture of CL and DEP-labelled CL, which up to now has not been separated, behaves chromatographically (fractogel; HPLC: TLC), in respect to release of DEP and ...
Gadelhak G G - - 1994
We examined the incorporation of four radioactive fatty acids, 18:1n-9, 18:2n-6, 20:4n-6 and 20:5n-3, into cellular lipids of hemocytes from tobacco hornworms, Manduca sexta. Most of the radioactivity associated with 18:1n-9 was recovered from triacylglycerols (TGs), and the radioactivity associated with 18:2n-6 was heavily incorporated into phospholipids (PLs) and TGs. ...
Oguchi A - - 1994
In bullfrog (Rana catesbeiana) tadpoles, the lung begins to function at an advanced stage of metamorphosis. As a preliminary step for investigation of the mechanisms involved in lung maturation, pulmonary surfactant was prepared from tadpoles at advanced stages of metamorphosis and its biochemical properties were analyzed. Surfactant phospholipid analysis revealed ...
Major C - - 1994
We describe a relatively simple and sensitive method to measure femtomole amounts of phosphatidic acid in cells. Phosphatidic acid was extracted from cells in the presence of 1-heptadecanoyl-2-heptadecanoyl-sn-glycero-3-phosphate as an internal standard, purified by two-dimensional thin-layer chromatography, and hydrolyzed to its constituent free fatty acids which were then derivatized to ...
Patton G M - - 1994
Studies were performed to compare the extent of fatty acid incorporation into liver phosphatidylcholines (PCs) by acyl remodeling and by de novo synthesis. To this end, isolated rat livers were first perfused with palmitoleic acid (16:1) and [2-3H]glycerol and then with 17:1 fatty acid and nonradiolabeled glycerol that resulted in ...
Ellingson J S - - 1994
In rat liver microsomes, [3H]serine was incorporated primarily into the two most abundant molecular species of microsomal phosphatidylserine (PS), 18:0/20:4 and 18:0/22:6, by Ca(2+)-dependent base exchange. The pattern of PS molecular species synthesized was very similar to the species composition of PS and markedly different from the species composition of ...
Christensen S - - 1994
Neutralized perchloric acid extracts of intra-abdominally proliferating Ehrlich mouse ascites-tumour cells harvested after 24 h exposure to [2-3H]inositol were analysed by Mono Q HR5/5 anion-exchange h.p.l.c. using an ammonium formate/phosphoric acid gradient or by ambient-pressure small-column anion-exchange chromatography (Bio-Rad AG 1-X8, 200-400 mesh). The results showed that cellular ATP contained ...
Lundqvist C - - 1994
Phospholipase D has been shown to be a key enzyme in the signal transduction systems involved in neutrophil activation. In the presence of ethanol, the enzyme catalyzes a transphosphatidylation reaction through which phosphatidylethanol is formed instead of the normal product phosphatidic acid. The effects of ethanol on the formation of ...
Taniguchi M - - 1994
The turtle olfactory epithelium was treated with suspensions of various lipids and their effects on the olfactory responses were examined by measuring the olfactory bulbar responses. The phosphatidylserine (PS)-treatment greatly lowered the threshold for n-valeric acid and enhanced its responses at all concentrations examined. The responses to isovaleric acid and ...
Bhat B G - - 1994
The lipid cofactor requirement of hepatic monoacylglycerol acyltransferase (MGAT) (EC 2.3.1.22) was studied in Triton X-100/lipid-mixed micelles. Anionic phospholipids and anionic lysophospholipids stimulated MGAT activity, whereas fatty acids and sphingosine inhibited enzyme activity. Phosphatidic acid was a potent activator, stimulating MGAT 11-fold at 4.2 mol %. Kinetic studies revealed that ...
Doering T L - - 1994
Glycolipid A, the precursor of the glycosyl-phosphatidylinositol (GPI) anchor of the trypanosome variant surface glycoprotein, is constructed in two phases. First, the glycan is assembled on phosphatidylinositol (PI), yielding a glycolipid termed A'. Second, glycolipid A' undergoes fatty acid remodelling, by deacylation and reacylation, to become the dimyristoyl species glycolipid ...
Salgo M G - - 1994
The activation of phospholipase A2 (PLA2) by lipid ozonation products is reported. The principal products from the ozonation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) are 1-palmitoyl-2-[8-[3(5-octyl-1,2,4-trioxolan-3-yl)octanoyl]--sn-gly cero-3- phosphocholine (PC-Criegee ozonide) and 1-palmitoyl-2-(9-oxononanoyl)-sn-glycero-3- phosphocholine (PC-aldehyde). (See Figure 1 for structures.) Here we test the hypothesis that these two compounds are mediators of ozone toxicity. ...
Fonlupt P - - 1994
The incorporation of [3H]arachidonic acid (20:4n-6) into rat brain membranes and its mobilization in response to norepinephrine, a relevant neuromediator were studied. The most efficient [3H]20:4n-6 incorporation was in inositol glycerophospholipids (PI) where it reached a plateau after 10 min incubation, while this incorporation was very weak in choline glycerophospholipids ...
Randazzo P A - - 1994
ADP-ribosylation factor (ARF) is a 21-kDa GTP binding protein that regulates eukaryotic membrane traffic. Both the binding and hydrolysis of GTP by ARF have been shown to be necessary for this function. However, purified mammalian ARF lacks intrinsic GTPase activity (< 0.0015 min-1). We document the presence, in bovine brain ...
Hashizume T - - 1994
The action of phosphatidic acid generated from membrane phospholipids on phospholipase A2 activation in rabbit platelets was investigated. When [3H]arachidonic acid-labelled platelets were treated with phorbol 12-myristate 13-acetate (PMA) and the membranes isolated from the cells incubated at 37 degrees C with 50 microM CaCl2 and 50 microM guanosine 5'-O-(3-thiotriphosphate) ...
Yang H C - - 1994
Two forms of Ca(2+)-independent cytosolic phospholipases A2 were separated by Sephadex G-75 column chromatography. N-Acetylneuraminic acid, gangliosides, and sialoglycoproteins inhibited both phospholipases A2 in a concentration dependent manner, but colominic acid, poly(2,8-N-acetylneuraminic acid), had no effect on enzymic activities. Interactions between phospholipases A2 and sialoglycoconjugates may be involved in the ...
Pinson A - - 1994
Incubation of cultured ventricular cardiomyocytes with high oligomycin concentrations (100 micrograms/ml), either alone or combined with 2-deoxyglucose (20 mM), led to the rapid depletion of cellular ATP. Inositol (poly)phosphate production decreased, and 6-keto PGF1 alpha production was increased. In cells depleted of ATP, either by low oligomycin concentrations or by ...
Bernhard W - - 1994
Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are the major phospholipids of the gastric mucosal surface barrier and chiefly originate from mucous cells. Among these phospholipids PC with palmitic acid as its hydrophobic moieties is believed to protect the gastric mucosa by its hydrophobic properties. We investigated the phospholipid synthesis of isolated ...
Cahoon E. B. - - 1994
Studies were conducted to characterize the metabolism of the unusual fatty acid petroselinic acid (18:1cis[delta]6) in developing endosperm of the Umbelliferae species coriander (Coriandrum sativum L.) and carrot (Daucus carota L.). Analyses of fatty acid compositions of glycerolipids of these tissues revealed a dissimilar distribution of petroselinic acid in triacylglycerols ...
Brett R - - 1994
Glycerophospholipids and sphingolipids typical of the myelin sheath have been examined for the formation of thiobarbituric acid reactive materials after attack by hydroxyl free radicals. Thiobarbituric acid (TBA) reactive materials are formed following exposure of phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE) to hydroxyl radical attack in the order PS ...
Wakabayashi S - - 1994
We examined effects of acute unilateral enucleation on incorporation from blood of intravenously injected unsaturated [1-14C]arachidonic acid ([14C]AA) and [1-14C]docosahexaenoic acid ([14C]DHA), and of saturated [9,10-3H]palmitic acid ([3H]PA), into visual and nonvisual brain areas of awake adult Long-Evans hooded rats. Regional cerebral metabolic rate for glucose (rCMRglc) values also were ...
Ford D A - - 1994
Although recent studies have demonstrated the existence of the requisite enzymic machinery necessary for the shuttling of vinyl ether linkages through polar head group remodeling, the relative rates of plasmalogen de novo synthesis and polar head group remodeling are unknown. Pulse-chase radiolabeling of perfused rabbit hearts with [1-3H]hexadecanol demonstrated the ...
Cho Y - - 1994
Ceramides and phospholipids constitute two important structural lipids of normal skin that are notably rich in polyunsaturated fatty acids. Although linoleic acid (LA) is high in the ceramides, the localization of its 15-lipoxygenase product, 13-hydroxyoctadecadienoic acid (13-HODE) in the epidermis is unknown. In this study, we investigated the relative incorporation ...
McNulty S - - 1994
The potential role of phospholipases in mediating melatonin-dependent inhibition of adenylyl cyclase was investigated in pars tuberalis (PT) cultures. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulated the release of choline metabolites and increased the transphosphatidylation reaction. The calcium ionophore A23187 stimulated the release of arachidonic acid from cultures. These observations ...
de Lederkremer R M - - 1994
Two glycoinositol phospholipids (GIPL A and GIPL B) have been purified from epimastigotes of Trypanosoma cruzi at the logarithmic phase of growth (2 days). The GIPLs differ mainly in the lipid moiety and are similar to the lipopeptidophosphoglycan (LPPG) previously isolated from epimastigotes at the stationary phase (4-5 days). [3H]-palmitic ...
Andersson L - - 1994
The 2-ester bond of 14C-2-arachidonyl phosphatidylethanolamine (PE) was hydrolyzed faster than that of 3H-2-arachidonyl phosphatidylcholine (PC) by human pancreatic phospholipase A2 (PLA2) with mixed PE-PC (1:9 w/w) liposomes of pure sonicated PE or PC as substrate. The PC portion of the mixed PE-PC liposomes was more readily attacked by PLA2 ...
Heise N - - 1994
Since glycosylphosphatidylinositol is the most common form of attachment of proteins to membranes in T. cruzi, and that this parasite depends on surface-mediated interactions for survival within the vector and mammalian host, it is probable that a drug which interfers with the metabolism of glycosylphosphatidylinositol (GPI) could be successfully employed ...
Rajasekharan R - - 1994
A photoreactive derivative of phosphatidylethanolamine, N-(4-azidobenzoyl)phosphatidylethanolamine (AB-PE), was synthesized by acylation of phosphatidylethanolamine with an N-hydroxysuccinimide ester of 4-azidobenzoic acid. The substantial photosensitivity exhibited by AB-PE correlated with a marked decrease in the absorption spectra of the compound. The compound proved sensitive to lipase and phospholipase A2 hydrolysis but resistant ...
Song J - - 1994
An early response to epidermal growth factor in A431 cells is the generation of diglyceride, a physiological activator of protein kinase C. By differentially prelabeling cellular phospholipids with [3H]arachidonate and [3H]myristate, which are incorporated primarily into phosphatidylinositol and phosphatidylcholine, respectively, we have found that epidermal growth factor induces an increase ...
Takino T - - 1994
With the aim of developing of emulsion carrier systems for lipophilic drugs with the potential for prolonged circulation in the blood or hepatic targeting, the in vivo disposition of four model compounds, i.e., [3H]prostaglandin E1, [3H]retinoic acid, [14C]cholesterol, and [14C]cholesteryl oleate with calculated log PC(oct) values of 2.15, 6.61, 9.46, ...
Hatch G M - - 1994
The pathway for the biosynthesis of new cardiolipin was investigated in the isolated perfused intact rat heart. Isolated rat hearts were perfused in the Langendorff mode for up to 60 min with Krebs-Henseleit buffer containing 0.1 microM [U-14C]glycerol. Analysis of radioactivity incorporated into phospholipids in the organic phase revealed an ...
Ide T - - 1994
Effects of various phospholipid preparations from soybean and egg yolk origins on various indices for lipid biosynthesis in the liver were compared in fasted-refed rats. Phospholipid preparations employed were soybean phospholipid mainly consisting of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidic acid (soybean PL), egg phospholipid mainly consisting of phosphatidylcholine and phosphatidylethanolamine ...
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 ...
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