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At least 793 records · Page 44Linked to original sources
PubMed1995

Farnesyl thiotriazole, a potent neutrophil agonist and structurally novel activator of protein kinase C.

Farnesylcysteine derivatives can initiate or inhibit superoxide (O2-) release in neutrophils. The mechanism by which one of these derivatives, farnesyl thiotriazole (FTT), initiates O2- release in neutrophils is the subject of this paper. Treatment of guinea pig neutrophils with FTT results in the rapid release of O2- by a route shown to be independent of the chemotactic peptide N-formyl-Met-Leu-Phe (fMLP) receptor. The signal transduction pathway utilized by the chemoattractant fMLP is generally accepted as the paradigm for receptor-mediated stimulation of O2- production. Antagonists of fMLP had no effect on FTT-induced O2- release, and pretreatment of neutrophils with fMLP had no effect on the ability of FTT to trigger further O2- generation. In fact, FTT behaves like a typical protein kinase C (PKC) activator. It promotes phosphorylation of the 47-kDa subunit of the NADH oxidase complex (p47-phox) in neutrophils, and this phosphorylation is specifically blocked by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an antagonist of PKC. FTT is also shown to activate PKC in vitro in a specific and saturable fashion. FTT is approximately equipotent with (S)-diolein, a physiologically relevant activator of this kinase. FTT represents a new, and quite novel, structure for a PKC activator. PKC activators include diglycerides and the structurally diverse tumor promoters.

Animals↗
PubMed1992

Stereochemical and positional specificity of the lipase/acyltransferase produced by Aeromonas hydrophila.

Aeromonas species secrete a glycerophospholipid-cholesterol acyltransferase (GCAT) which shares many properties with mammalian plasma lecithin-cholesterol acetyltransferase (LCAT). We have studied the stereochemical and positional specificity of GCAT against a variety of lipid substrates using NMR spectroscopy as well as other assay methods. The results show that both the primary and secondary acyl ester bonds of L-phosphatidylcholine can be hydrolyzed but only the sn-2 fatty acid can be transferred to cholesterol. The enzyme has an absolute requirement for the L configuration at the sn-2 position of phosphatidylcholine. The secondary ester bond of D-phosphatidylcholine cannot be hydrolyzed, and this lipid is not a substrate for acyl transfer. In contrast to the phospholipases, but similar to LCAT, the enzyme does not interact stereochemically with the phosphorus of phosphatidylcholine. In fact, the phosphorus is not required for enzyme activity, as GCAT will also hydrolyze monolayers of diglyceride, although at much lower rates.

Acyltransferases↗
PubMed1987

Analysis of a specific oxygenation reaction of soybean lipoxygenase-1 with fatty acids esterified in phospholipids.

Soybean lipoxygenase was reacted with phosphatidylcholine (at pH 9, with 10 mM deoxycholate), and the oxygenation products were analyzed by high-pressure liquid chromatography, UV, gas chromatography-mass spectrometry (GC-MS), and NMR. The structures of the intact glycerolipid products were established by GC-MS of diglycerides recovered by phospholipase C hydrolysis and by proton NMR of the intact phosphatidylcholine. These analyses, together with analyses of the transesterified fatty acids, indicated that arachidonyl and linoleoyl moieties in the phosphatidylcholine were converted exclusively to the 15(S)-hydroperoxy-5(Z),8(Z),11(Z),13(E)-eicosatetraenoate and 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoate analogues, respectively. Control experiments proved that the intact phospholipid (and not hydrolyzed/reesterified fatty acid) was the true substrate of the oxygenation reaction. Phosphatidylethanolamine and phosphatidylinositol lipids were also substrates for specific oxygenation by the soybean lipoxygenase. The results provide concrete evidence that fatty acids esterified in phospholipid can be subject to highly specific oxygenation by a lipoxygenase enzyme.

Chromatography, High Pressure Liquid↗
PubMed1977

Characterization of two major neutral glyceroglucolipids of the human gastric content.

Two major neutral glyceroglucolipids (A and B) have been isolated from lipid extract of human gastric content by the procedure involving column fractionation on DEAE-Sephadex, silicic acid, and thin-layer chromatography. Both glycolipids contained glucose, glyceryl ethers, and fatty acids. The structures of these glycolipids were identified by mild alkaline methanolysis, oxidation with periodate and chromium trioxide, and permethylation studies. Based on the obtained data, we propose that glycolipid A is a monoalkylmonoacylglyceryl hexaglucoside and glycolipid B is a monoalkylmonoacylglyceryl octaglucoside. The diglyceride portion of these glycolipids consists mostly of 1-O-alkyl-2-O-acylglycerol.

Diglycerides↗
PubMed2003

Improving virgin olive oil quality by means of innovative extracting biotechnologies.

Three major virgin olive oil varieties (Dritta, Leccino, and Coratina) extracted by a modern centrifugation system aided with a new plant enzyme preparation (having prevalently pectolytic activity) were characterized. These oils showed a clearly enhanced quality standard, owing to higher levels of some important minor components (phenolics, volatiles, tocopherols, carotenes, and chlorophylls) and to frequently lower concentrations of oxidized triglycerides and diglycerides. The oils were therefore characterized by lower susceptibility to oxidation and longer shelf life, and their flavor, aroma, and color features appeared to be significantly improved. The saponifiable fraction was practically not affected as the enzymatic effects involved only the membranes of the oil droplets, where the nonglyceridic compounds are essentially located.

Biotechnology↗
PubMed1993

Immunotargeting of liposomes containing lipophilic antitumor prodrugs.

Potential therapeutic applications of recently developed liposomes with a reduced affinity to the reticuloendothelial systems and a prolonged circulation time as targeting systems for lipophilic prodrugs were examined. In these studies, liposomes composed of phosphatidylcholine and cholesterol, additionally containing monosialoganglioside (GM1) or polyethylene glycol conjugated to phosphatidylethanolamine (PEG-PE), were used. Three antitumor lipophilic prodrugs, N-trifluoroacetyl-adriamycin-14-valerate (AD32), araC-diphosphate-diglyceride (araCdPdG), and 3',5'-o-dipalmitoyl-5-fluoro-2'-deoxyuridine (dpFUdR), were used to examine the effect of lipophilic prodrug incorporation into long-circulating liposomes and immunoliposomes on their biodistribution in mouse. Biodistribution studies with antibody-free liposomes containing lipophilic prodrugs showed that the activities of GM1 or PEG2000-PE in prolonging the circulation time of liposomes appeared to be preserved in the presence of each of the three lipophilic prodrugs at a drug/lipid molar ratio of 3:97. The effect of lipophilic prodrug incorporation on target binding of immunoliposomes was then examined using a mouse model. Incorporation of AD232 or dpFUdR into immunoliposomes, directed to the normal endothelium, did not affect the targetability of immunoliposomes, suggesting a potential effectiveness of these lipophilic prodrug-containing immunoliposomes in therapy for lung tumors. On the contrary, incorporation of araCdPdG resulted in significantly reduced target binding of immunoliposomes by yet unknown mechanism(s).

Animals↗
PubMed1996

Synthesis of non-hydroxy-galactosylceramides and galactosyldiglycerides by hydroxy-ceramide galactosyltransferase.

Galactosylceramide (GalCer) is the major glycolipid in brain. In order to characterize the activity of brain UDPgalactose: ceramide galactosyltransferase (CGalT), it has been stably expressed in CGalT-negative Chinese hamster ovary (CHO) cells. After fractionation of transfected cells, CHO-CGT, on sucrose gradients, the activity resides at the density of endoplasmic reticulum and not of Golgi. A lipid chromatogram from CHO-CGT cells revealed two new iodine-staining spots identified as GalCer, since they comigrate with GalCer standards, can be metabolically labelled with [3H]galactose, are recognized by anti-GalCer antibodies, and are resistant to alkaline hydrolysis. A third [3H]galactose lipid was identified as galactosyldiglyceride. In the homogenate CGalT displays a 25-fold preference for hydroxy fatty acid-containing ceramides. Remarkably, endogenous GalCer of transfected cells contains exclusively non-hydroxy fatty acids: fast atom bombardment and collision-induced dissociation mass spectrometric analysis revealed mainly C16:0 in the lower GalCer band on TLC and mainly C22:0 and C24:0 in the upper band. Our results suggest that CGalT galactosylates both hydroxy- and non-hydroxy fatty acid-containing ceramides and diglycerides, depending on their local availability. Thus, CGalT alone may be responsible for the synthesis of hydroxy- and non-hydroxy-GalCer, and galactosyldiglyceride in myelin.

Animals↗
PubMed1976

The esterification of exogenous fatty acids by adipose tissue of hypertriglyceridaemic subjects with or without diabetes mellitus.

1. The esterification of exogenous palmitate to diglyceride and triglyceride in adipocytes was studied in obese and diabetic patients with and without hypertriglyceridaemia. The rate of esterification correlated significantly with the triglyceride content of adipocytes. 2. In diabetic patients with hypertriglyceridaemia, the rate of esterification to triglyceride was significantly greater than in diabetic patients with normotriglyceridaemia. This difference could not be attributed to differences in glucose tolerance or to the degree of obesity. 3. Fasting plasma insulin levels were greater in the hypertriglyceridaemic group than in the normotriglyceridaemic group. The difference in esterification rates could have been due to differences in adipocyte size. 4. The esterification of fatty acid in adipose tissue of diabetic patients was lower than in non-diabetic subjects and this difference could not be accounted for by differences in adipocyte size or differences in the intracellular pools of fatty acid in adipose tissue. 5. The role of esterification of exogenous fatty acids in adipose tissue as a possible determinant of the uptake of glyceride fatty acids from plasma is discussed.

Adipose Tissue↗
PubMed2002

The antilipolytic agent 3,5-dimethylpyrazole inhibits insulin release in response to both nutrient secretagogues and cyclic adenosine monophosphate agonists in isolated rat islets.

This study intended to test the hypothesis that intracellular lipolysis in the pancreatic beta cells is implicated in the regulation of insulin secretion stimulated by nutrient secretagogues or cyclic adenosine monophosphate (cAMP) agonists. Indeed, although lipid signaling molecules were repeatedly reported to influence beta-cell function, the contribution of intracellular triglycerides to the generation of these molecules has remained elusive. Thus, we have studied insulin secretion of isolated rat pancreatic islets in response to various secretagogues in the presence or absence of 3,5-dimethylpyrazole (DMP), a water-soluble and highly effective antilipolytic agent, as previously shown in vivo. In vitro exposure of islets to DMP resulted in an inhibition (by approximately 50%) of the insulin release stimulated not only by high glucose, but also by another nutrient secretagogue, 2-ketoisocaproate, as well as the cAMP agonists 3-isobutyl-1-methylxanthine and glucagon. The inhibitory effect of DMP, which was not due to alteration of islet glucose oxidation, could be reversed upon addition of sn-1,2-dioctanoylglycerol, a synthetic diglyceride, which activates protein kinase C. The results provide direct pharmacologic evidence supporting the concept that endogenous beta-cell lipolysis plays an important role in the generation of lipid signaling molecules involved in the control of insulin secretion in response to both fuel stimuli and cAMP agonists.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Induction of apoptosis and potentiation of ceramide-mediated cytotoxicity by sphingoid bases in human myeloid leukemia cells.

Prior studies demonstrated that ceramide promotes apoptotic cell death in the human myeloid leukemia cell lines HL-60 and U937 (Jarvis, W. D., Kolesnick, R. N., Fornari, F. A., Jr., Traylor, R. S., Gewirtz, D. A., and Grant, S. (1994) Proc. Natl. Acad. Sci. U. S. A. 91, 73-77), and that this lethal process is potently suppressed by diglyceride (Jarvis, W. D., Fornari, F. A., Jr., Browning, J. L., Gewirtz, D. A., Kolesnick, R. N., and Grant, S. (1994) J. Biol. Chem. 269, 31685-31692). The present findings document the intrinsic ability of sphingoid bases to induce apoptosis in HL-60 and U937 cells. Exposure to either sphingosine or sphinganine (0. 001 10 microM) for 6 h promoted apoptotic degradation of genomic DNA as indicated by (a) electrophoretic resolution of 50-kilobase pair DNA loop fragments and 0.2-1.2-kilobase pair DNA fragment ladders on agarose gels, and (b) spectrofluorophotometric determination of the formation and release of double-stranded fragments and corresponding loss of integrity of bulk DNA. DNA damage correlated directly with reduced cloning efficiency and was associated with the appearance of apoptotic cytoarchitectural traits. At sublethal concentrations (</=750 nM), however, sphingoid bases synergistically augmented the apoptotic capacity of ceramide (10 microM), producing both a leftward shift in the ceramide concentration-response profile and a pronounced increase in the response to maximally effective levels of ceramide. Thus, sphingosine and sphinganine increased both the potency and efficacy of ceramide. The apoptotic capacity of bacterial sphingomyelinase (50 milliunits/ml) was similarly enhanced by either (a) acute co-exposure to highly selective pharmacological inhibitors of protein kinase C such as calphostin C and chelerythrine or (b) chronic pre-exposure to the non-tumor-promoting protein kinase C activator bryostatin 1, which completely down-modulated total assayable protein kinase C activity. These findings demonstrate that inhibition of protein kinase C by physiological or pharmacological agents potentiates the lethal actions of ceramide in human leukemia cells, providing further support for the emerging concept of a cytoprotective function of the protein kinase C isoenzyme family in the regulation of leukemic cell survival.

Apoptosis↗
PubMed1996

Phospholipase D-derived products in the regulation of 12-O-tetradecanoylphorbol-13-acetate-stimulated prostaglandin synthesis in madin-darby canine kidney cells.

Madin-Darby canine kidney (MDCK) cells stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA) in the presence of ethanol synthesize phosphatidylethanol (PEt) instead of phosphatidic acid (PA) and diglyceride (DG). We have used ethanol to block the production of phospholipase D (PLD)-derived PA and DG (from PA hydrolysis) to study their role in signal transduction. In MDCK cells, TPA-stimulated prostaglandin E2 (PGE2) synthesis was inhibited by ethanol at concentrations which inhibit PA and DG formation. In addition, TPA elicited a prolonged increase in PGE2 synthesis that is dependent upon continuous activation of PLD. The TPA-stimulated translocation of protein kinase Calpha (PKCalpha) from cytosol to membrane was unaffected by ethanol. This suggests that PLD-derived products act downstream of PKC in TPA-stimulated prostaglandin synthesis. The calcium ionophore, A23187, did not activate PLD, and PGE2 synthesis in response to A23187 was unaffected by ethanol. TPA increased prostaglandin endoperoxide H synthase (PGHS) activity and increased the amount of immunodetectable prostaglandin endoperoxide H synthase 2 (PGHS-2). A23187 did not induce PGHS-2 and A23187-stimulated PGE2 synthesis appears to be due to the constitutively expressed PGHS-1. Blocking the formation of PLD-derived products, PA and DG, inhibited the induction of PGHS-2 by TPA. These results indicate that prolonged PGE2 synthesis in response to TPA is due to the continuous induction of PGHS-2, which is dependent upon PLD activation. In contrast, induction of PGHS-2 by epidermal growth factor was not affected by ethanol. Epidermal growth factor did not induce PKCalpha translocation nor activate PLD. Taken together, these data suggest that PLD-derived PA or DG act as second messengers in the induction of PGHS-2 by PKC-dependent pathways. The demonstration that inhibition of TPA-induced PA formation inhibits Raf-1 translocation in MDCK cells (Ghosh, S., Strum, J. C., Sciorra, V. A., Daniel, L. W. , and Bell, R. M. (1996) J. Biol. Chem. 271, 8472-8480) suggests that PA is the active PLD metabolite in TPA-stimulated signaling.

Animals↗
PubMed1997

Opioid peptide gene expression in the primary hereditary cardiomyopathy of the Syrian hamster. I. Regulation of prodynorphin gene expression by nuclear protein kinase C.

Prodynorphin gene expression was investigated in adult ventricular myocytes isolated from normal (F1B) or cardiomyopathic (BIO 14.6) hamsters. Prodynorphin mRNA levels were higher in cardiomyopathic than in control myocytes and were stimulated by treatment of control cells with the protein kinase C (PKC) activator 1, 2-dioctanoyl-sn-glycerol. Both chelerythrine and calphostin C, two PKC inhibitors, abolished the stimulatory effect of the diglyceride and significantly reduced prodynorphin gene expression in cardiomyopathic myocytes. Nuclear run-off experiments indicated that the prodynorphin gene was regulated at the transcriptional level and that treatment of nuclei isolated from control cells with 1, 2-dioctanoyl-sn-glycerol increased prodynorphin gene transcription, whereas chelerythrine or calphostin C abolished this transcriptional effect. Direct exposure of nuclei isolated from cardiomyopathic myocytes to these inhibitors markedly down-regulated the rate of gene transcription. The expression of PKC-alpha, -delta, and -epsilon, as well as PKC activity, were increased in nuclei of cardiomyopathic myocytes compared with nuclei from control cells. The levels of both intracellular and secreted dynorphin B, a biologically active product of the gene, were higher in cardiomyopathic than in control cells and were stimulated or inhibited by cell treatment with 1,2-dioctanoyl-sn-glycerol or PKC inhibitors, respectively.

Animals↗
PubMed2002

Accumulation of the lipid A precursor UDP-2,3-diacylglucosamine in an Escherichia coli mutant lacking the lpxH gene.

The lpxH gene encodes the UDP-2,3-diacylglucosamine-specific pyrophosphatase that catalyzes the fourth step of lipid A biosynthesis in Escherichia coli. To confirm the function of lpxH, we constructed KB21/pKJB5. This strain contains a kanamycin insertion element in the chromosomal copy of lpxH, complemented by plasmid pKJB5, which is temperature-sensitive for replication and harbors lpxH(+). KB21/pKJB5 grows at 30 degrees C but loses viability at 44 degrees C, demonstrating that lpxH is essential. CDP-diglyceride hydrolase (Cdh) catalyzes the same reaction as LpxH in vitro but is non-essential and cannot compensate for the absence of LpxH. The presence of Cdh in cell extracts interferes with the LpxH assay. We therefore constructed KB25/pKJB5, which contains both an in-frame deletion of cdh and a kanamycin insertion mutation in lpxH, covered by pKJB5. When KB25/pKJB5 cells are grown at 44 degrees C, viability is lost, and all in vitro LpxH activity is eliminated. A lipid migrating with synthetic UDP-2,3-diacylglucosamine accumulates in KB25/pKJB5 following loss of the covering plasmid at 44 degrees C. This material was converted to the expected products, 2,3-diacylglucosamine 1-phosphate and UMP, by LpxH. Pseudomonas aeruginosa contains two proteins with sequence similarity to E. coli LpxH. The more homologous protein catalyzes UDP-2,3-diacylglucosamine hydrolysis in vitro. The corresponding gene complements KB25/pKJB5 at 44 degrees C, but the less homologous gene does not. The accumulation of UDP-2,3-diacylglucosamine in our lpxH mutant is consistent with the observation that the lipid A disaccharide synthase LpxB, the next enzyme in the pathway, cannot condense two UDP-2,3-diacylglucosamine molecules, but instead utilizes UDP-2,3-diacylglucosamine as its donor and 2,3-diacylglucosamine 1-phosphate as its acceptor.

Amino Acid Sequence↗
PubMed2003

Ceramide selectively displaces cholesterol from ordered lipid domains (rafts): implications for lipid raft structure and function.

Ceramide is a membrane lipid involved in a number of crucial biological processes. Recent evidence suggests that ceramide is likely to reside and function within lipid rafts; ordered sphingolipid and cholesterol-rich lipid domains believed to exist within many eukaryotic cell membranes. Using lipid vesicles containing co-existing raft domains and disordered fluid domains, we find that natural and saturated synthetic ceramides displace sterols from rafts. Other raft lipids remain raft-associated in the presence of ceramide, showing displacement is relatively specific for sterols. Like cholesterol-containing rafts, ceramide-rich "rafts" remain in a highly ordered state. Comparison of the sterol-displacing abilities of natural ceramides with those of saturated diglycerides and an unsaturated ceramide demonstrates that tight lipid packing is critical for sterol displacement by ceramide. Based on these results, and the fact that cholesterol and ceramides both have small polar headgroups, we propose that ceramides and cholesterol compete for association with rafts because of a limited capacity of raft lipids with large headgroups to accommodate small headgroup lipids in a manner that prevents unfavorable contact between the hydrocarbon groups of the small headgroup lipids and the surrounding aqueous environment. Minimizing the exposure of cholesterol and ceramide to water may be a strong driving force for the association of other molecules with rafts. Furthermore, displacement of sterol from rafts by ceramide is very likely to have marked effects upon raft structure and function, altering liquid ordered properties as well as molecular composition. In this regard, certain previously observed physiological processes may be a result of displacement. In particular, a direct connection to the previously observed sphingomyelinase-induced displacement of cholesterol from plasma membranes in cells is proposed.

Cell Membrane↗
PubMed1991

Cytoplasmic lipid bodies of neutrophils: formation induced by cis-unsaturated fatty acids and mediated by protein kinase C.

Lipid bodies, nonmembrane-bound cytoplasmic inclusions, serve as repositories of esterified arachidonate and are increased in cells associated with inflammatory reactions. We have evaluated stimuli and mechanisms responsible for lipid body formation within human polymorphonuclear leukocytes (PMNs). Arachidonic acid and oleic acid stimulated dose-dependent formation of lipid bodies over 0.5-1 h. Other C20 and C18 fatty acids were less active and demonstrated rank orders as follows: cis-unsaturated fatty acids were much more active than trans-fatty acids, and activity diminished with decreasing numbers of double bonds. Lipid bodies elicited in vitro with cis-fatty acids were ultrastructurally identical to lipid bodies present in PMNs in vivo. Lipid body induction was not because of fatty acid-elicited oxidants or fatty acid-induced ATP depletion. Cis-fatty acid-induced activation of protein kinase C (PKC) was involved in lipid body formation as evidenced by the capacity of other PKC activators, 1-oleoyl-2-acetyl-glycerol and two active phorbol esters, phorbol myristate acetate, and phorbol 12,13 dibutyrate, but not an inactive phorbol, to induce lipid body formation. The PKC inhibitor, 1-O-hexadecyl-2-O-methyl-glycerol, inhibited PMN lipid body formation induced by oleic and arachidonic acids and by 1-oleoyl-2-acetyl-glycerol and phorbol myristate acetate. Other PKC inhibitors (staurosporine, H-7) also inhibited lipid body formation. Formation of lipid bodies in PMNs is a specific cellular response, stimulated by cis-fatty acids and diglycerides and apparently mediated by PKC, which results in the mobilization and deposition of lipids within discrete, ultrastructurally defined cytoplasmic domains.

Adenosine Triphosphate↗
PubMed1991

Carbachol stimulates a different phospholipid metabolism than nerve growth factor and basic fibroblast growth factor in PC12 cells.

We have examined 1,2-diglycerides (DGs) generated in PC12 cells in response to the muscarinic agonist carbachol and compared them with those generated in response to the differentiation factors nerve growth factor and basic fibroblast growth factor. Whereas carbachol stimulates a greater release of inositol phosphates, all three agonists generate similar levels of DGs. In this report, we have analyzed the molecular species of PC12 DGs generated in response to these three agonists. Additionally, we have analyzed the molecular species of PC12 phospholipids. The data indicate that 1) after 1 min of either nerve growth factor or basic fibroblast growth factor stimulation, DGs arise primarily from phosphoinositide hydrolysis; 2) in contrast, after 1 min of carbachol stimulation, DG are generated equally by both phosphoinositide and phosphatidylcholine hydrolysis; and 3) after 15 min of stimulation by any of these agonists, DGs are generated largely by phosphatidylcholine hydrolysis, with a smaller component arising from the phosphoinositides. These results suggest that at least part of the mechanism by which PC12 cells distinguish between different agonists is via alterations in phospholipid sources and kinetics of DG generation.

Animals↗
PubMed1975

High-speed liquid chromatograhic separation of glycerides, fatty acids and sterols.

The high-speed liquid chromatographic separation and detection of triglycerides, diglycerides, fatty acid and sterols was carried out to permit the analyses of total lipids from soybeans and soybean food. The study was conducted with a Varian Aerograph LC 1200 liquid chromatograph equipped with a hydrogen flame ionization detector. Linear-gradient, solvent-flow programming was used. Separation of the total lipids by the gradient was achieved in 30 minutes and the column prepared for the next analysis by washing with solvents. The detector response curves for authentic compounds were linear and equivalent to within 2.3% error, based on the response to 1-monopalmitin. The minimum detectable amounts of the authentic substances were between 0.1 and 1.4mug. When a three-stranded wire was used instead of single filament wire, the sensitivity was increased by 37%.

Chromatography, High Pressure Liquid↗
PubMed2005

Dietary ganglioside decreases cholesterol content, caveolin expression and inflammatory mediators in rat intestinal microdomains.

Membrane microdomains rich in cholesterol and sphingolipids, including gangliosides (GGs), are known to be important regions for cell signaling and binding sites for various pathogens. Cholesterol depletion inhibits the cellular entry of pathogens and also reduces inflammatory signals by disrupting microdomain structure. Our previous study showed that dietary gangliosides increased total ganglioside incorporation while decreasing cholesterol in the intestinal mucosa. We hypothesized that diet-induced reduction in cholesterol content in the intestinal mucosa disrupts microdomain structure resulting in reduced pro-inflammatory signals. Male weanling Sprague-Dawley rats were fed semipurified diets for 2 weeks. Experimental diets were formulated to include either ganglioside-enriched lipid (GG diet, 0.02% gangliosides [w/w of diet] ) or polyunsaturated fatty acid (PUFA diet, 1% arachidonic acid and 0.5% docosahexaenoic acid, w/w of total fat), in a control diet containing 20% fat. Levels of cholesterol, GG, caveolin, platelet activating factor (PAF), and diglyceride (DG) were measured in the microdomain isolated from the intestinal brush border. The GG diet increased total gangliosides by 50% with a relative increase in GD3 and a relative decrease in GM3. Cholesterol content was also reduced by 23% in the intestinal microdomain. These changes resulted in a significant decrease in the ratio of cholesterol to ganglioside. The GG diet and the PUFA diet were both associated with reduction in caveolin, PAF, and DG content in microdomains, whereas no change occurred in the ganglioside profile of animals fed the PUFA diet. Dietary gangliosides decrease the cholesterol/ganglioside ratio, caveolin, PAF and DG content in microdomains thus exerting a potential anti-inflammatory effect during gut development.

Animals↗