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Thierry Levade - One of the best experts on this subject based on the ideXlab platform.
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Method to Measure Sphingomyelin Synthase Activity Changes in Response to CD95L.
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Fatima Bilal, Thierry Levade, Michaël Pérès, Nathalie Andrieu-abadie, Bassam Badran, Ahmad Daher, Bruno SéguiAbstract:Sphingomyelin synthases 1 and 2 convert the anti-oncometabolite ceramide to Sphingomyelin, the most abundant sphingolipid in plasma membrane. CD95L-induced ceramide increase is associated with the caspase-dependent inhibition of Sphingomyelin synthesis, which enhances the mitochondrial route to apoptosis. Knocking down Sphingomyelin synthase 1 or inhibiting Sphingomyelin synthesis facilitates ceramide accumulation, cytochrome c release from mitochondria, and caspase-9 activation in cancer cell upon CD95L treatment. Here, we describe a method to monitor in situ Sphingomyelin synthase activity changes triggered by CD95L.
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On-Tissue Localization of Ceramides and Other Sphingolipids by MALDI Mass Spectrometry Imaging
2015Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other sphingolipids. Increasingly, altered or elevated levels of sphingolipids, sphingolipid metabolites, and sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other sphingolipid metabolites accumulate in tissues, specific ceramides and Sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or Sphingomyelinase. Multiple glycosphingolipid species were also detected. The newly generated library of sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and Sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and Sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and Sphingomyelin in tissues
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on tissue localization of ceramides and other sphingolipids by maldi mass spectrometry imaging
Analytical Chemistry, 2014Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other sphingolipids. Increasingly, altered or elevated levels of sphingolipids, sphingolipid metabolites, and sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other sphingolipid metabolites accumulate in tissues, specific ceramides and Sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or Sphingomyelinase. Multiple glycosphingolipid species were also detected. The newly generated library of sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and Sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and Sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and Sphingomyelin in tissues.
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degradation of fluorescent and radiolabelled Sphingomyelins in intact cells by a non lysosomal pathway
Biochimica et Biophysica Acta, 1995Co-Authors: Thierry Levade, Shimon Gatt, Fabienne Vidal, Stephane Vermeersch, Nathalie Andrieu, Robert SalvayreAbstract:Abstract The aim of the present study was to investigate the role of the entitled neutral, Sphingomyelinase in the non-lysosomal pathway of Sphingomyelin degradation by intact cells (Spence et al. (1983) J. Biol. Chem. 258, 8595–8600; Levade et al. (1991) J. Biol. Chem. 266, 13519–13529). The uptake and degradation of Sphingomyelin by intact living cells was studied using cell lines exhibiting a wide range of activity levels of acid, lysosomal and neutral Sphingomyelinases as determined in vitro on cell homogenates by their respective standard assays. For this purpose, neuroblastoma, skin fibroblasts, lymphoid and leukemic cell lines, some of them derived from patients with Niemann-Pick disease (deficient in the acid, lysosomal Sphingomyelinase) were incubated with radioactive, [ oleoyl - 3 H]Sphingomyelin or fluorescent, pyrene-sulfonylaminoundecanoyl-Sphingomyelin. Either compound was taken up by a pathway which was not receptor-mediated and hydrolyzed by all intact cells, including those derived from Niemann-Pick disease patients. Moreover, their degradation by the intact cells was not inhibited by treatment with chloroquine, indicating hydrolysis by a non-lysosomal Sphingomyelinase. The intracellular Sphingomyelin degradation rates showed no correlation with the activity of the ‘classical’ neutral Sphingomyelinase as determined in vitro. In particular, fibroblasts derived from Niemann-Pick patients lacking the lysosomal Sphingomyelinase, and having no detectable in vitro activity of the ‘classical’ neutral Sphingomyelinase, were able to degrade the exogenously supplied Sphingomyelins. Indeed, in vitro these cells were shown to exhibit neutral, magnesium- and dithiothreitol-dependent Sphingomyelinase activities, that might contribute to the non-lysosomal pathway for Sphingomyelin degradation to ceramide in intact cells.
J. Peter Slotte - One of the best experts on this subject based on the ideXlab platform.
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The importance of hydrogen bonding in Sphingomyelin's membrane interactions with co-lipids.
Biochimica et biophysica acta, 2015Co-Authors: J. Peter SlotteAbstract:Sphingomyelin is an important constituent of mammalian cell membranes. Its molecular structure is N-acyl-D-erythro-sphingosylphosphorylcholine. The N-acyls in Sphingomyelin often contain 16-24 carbons that are mostly saturated chains; however, the monounsaturated 24:1(Δ15c) acyl chain is also common. In addition to the more saturated nature of Sphingomyelins, compared to physiologically relevant glycerophospholipids, also their hydrogen bonding properties are very different from the glycerophospholipids. Sphingomyelins form extensive intramolecular hydrogen bonds (from the 3OH of the long-chain base to phosphate oxygens of the head group), but also intermolecular hydrogen bonding involving the NH of the long-chain base are important for Sphingomyelin (and sphingolipid) properties in membrane environments. Hydrogen bonding involving Sphingomyelin has been shown to markedly stabilize interactions with both cholesterol and ceramide in fully hydrated bilayers. Such interactions contribute to the propensity of saturated Sphingomyelin to form a liquid-ordered phase together with cholesterol, or a gel phase with saturated ceramides. The purpose of this review is to present recent experimental and computational evidence in support of the importance of hydrogen bonding for the interaction of Sphingomyelin with other membrane lipids.
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N-cholesteryl Sphingomyelin—A synthetic sphingolipid with unique membrane properties
Biochimica et biophysica acta, 2010Co-Authors: Christian Sergelius, J. Peter Slotte, Shou Yamaguchi, Yamamoto Tetsuya, Shigeo KatsumuraAbstract:Abstract A Sphingomyelin chimera in which the amide-linked acyl chain was replaced with cholesterol carbamate was prepared and its properties examined. The Sphingomyelin/cholesterol chimera (N-cholesterol-D-erythro-Sphingomyelin) was able to form unilamellar vesicles of defined size when extruded through 200 nm pore size membranes. These N-cholesteryl Sphingomyelin bilayers were resistant to solubilization by Triton X-100. When N-cholesteryl Sphingomyelin was added to N-palmitoyl Sphingomyelin (N-palmitoyl- d -erythro-Sphingomyelin) bilayers, it increased acyl chain order as determined by 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy. N-cholesteryl Sphingomyelin was, however, not as good an inducer of membrane order compared to cholesterol on a molar basis. Differential scanning calorimetry studies further showed that the miscibility of N-cholesteryl Sphingomyelin with N-palmitoyl- d -erythro-Sphingomyelin bilayers was non-ideal, and the effect of N-cholesteryl Sphingomyelin on the N-palmitoyl- d -erythro-Sphingomyelin gel–fluid transition enthalpy differed from that seen with cholesterol. Together with N-palmitoyl- d -erythro-Sphingomyelin, the N-cholesteryl Sphingomyelin chimera was able to form sterol-enriched ordered domains in a fluid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer. N-cholesteryl Sphingomyelin in the absence of N-palmitoyl- d -erythro-Sphingomyelin was unable to form such sterol-enriched ordered domains in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer. However, N-cholesteryl Sphingomyelin markedly increased the affinity of cholestatrienol for N-cholesteryl Sphingomyelin containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers, suggesting that N-cholesteryl Sphingomyelin was able to somehow stabilize sterol interaction in fluid bilayers. Based on our results, we conclude that N-cholesteryl Sphingomyelin behaved more like a cholesterol than a sphingolipid in fluid bilayer membranes. Because N-cholesteryl Sphingomyelin increased bilayer order, conferred resistance against detergent solubilization, and is not degradable by phospholipases A2, it could constitute a good lipocomplex matrix for drug delivery vehicles.
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Membrane properties of Sphingomyelins.
FEBS letters, 2002Co-Authors: Bodil Ramstedt, J. Peter SlotteAbstract:Sphingomyelin and phosphatidylcholine are important components in the external leaflet of cellular plasma membranes. In this review we compare the structure of these lipid molecules, with emphasis on the differences in hydrogen bonding capacity and membrane properties that arise from the small but significant differences in molecular structure. The membrane properties of Sphingomyelins and the implications that these have, or might have, in biological membranes and for raft function are further discussed.
Mutsumi Sugita - One of the best experts on this subject based on the ideXlab platform.
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Biochemical studies on sphingolipid of Artemia franciscana (I) isolation and characterization of Sphingomyelin.
Lipids, 2010Co-Authors: Hisao Kojima, Saki Itonori, Mutsumi Sugita, Takashi Inoue, Masahiro ItoAbstract:Sphingomyelin was isolated from cysts of the brine shrimp Artemia franciscana using QAE-Sephadex A25, Florisil and Iatrobeads column chromatographies. The chemical structure was identified using thin-layer chromatography, gas-liquid chromatography, infrared spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The ceramide moiety of Sphingomyelin consisted of stearic, arachidic, and behenic acids as fatty acids, and hexadeca-4- and heptadeca-4-sphingenines as sphingoids. By comparative analysis, the ceramide component of Artemia Sphingomyelin appears unique in invertebrates and vertebrates. Biological functions of Sphingomyelin have largely been investigated using mammalian-derived Sphingomyelin. In mammals, a wide variety of molecular species of Sphingomyelins have been reported, especially derived from nerve tissue, while the lower animal Artemia contains this unusual Sphingomyelin perhaps because of having a much simpler nervous system. The purified unusual Sphingomyelin derived from Artemia franciscana might be a very useful tool in elucidating the functions and mechanisms of action of this mediator.
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Sphingomyelins in four ascidians ciona intestinalis halocynthia roretzi halocynthia aurantium and styela clava
Journal of Oleo Science, 2009Co-Authors: Kazuhito Yokoi, Shogo Asano, Rei Hatano, Ryota Shinohara, Saki Itonori, Takashi Inoue, Mutsumi SugitaAbstract:Sphingomyelin is rarely found in lower animals, while sphingophospholipid is a characteristic of higher animals. In this study, Sphingomyelin was first isolated and characterized from ascidian Ciona intestinalis. Ascidian Sphingomyelin was prepared using ion exchange (QAE-Sphadex-A25) and silicic acid (Florisil and Iatrobeads) column chromatographies. The chemical structure was characterized by fatty acid analysis, sphingoid analysis, hydrogen fluoride degradation, acid hydrolysis, enzymatic hydrolysis, infrared analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The ceramide moieties of C. intestinalis Sphingomyelin consisted primarily of C16:0, C18:0, and C18:1 fatty acids and d18:2 sphingadiene. Furthermore, Sphingomyelins were isolated and characterized from 3 other ascidians, Halocynthia roretzi, Halocynthia aurantium, and Styela clava using the same methods. Comparative analysis of the Sphingomyelin structures in 4 ascidian species-C. intestinalis (Enterogona) and H. roretzi, H. aurantium, and S. clava (Pleurogona)-revealed that the major fatty acid composition of the ceramides was similar, and that they differed in minor components.
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Sphingomyelins in four ascidians ciona intestinalis halocynthia roretzi halocynthia aurantium and styela clava
Journal of Oleo Science, 2009Co-Authors: Kazuhito Yokoi, Shogo Asano, Rei Hatano, Ryota Shinohara, Saki Itonori, Takashi Inoue, Mutsumi SugitaAbstract:Sphingomyelin is rarely found in lower animals, while sphingophospholipid is a characteristic of higher animals. In this study, Sphingomyelin was first isolated and characterized from ascidian Ciona intestinalis. Ascidian Sphingomyelin was prepared using ion exchange (QAE-Sphadex-A25) and silicic acid (Florisil and Iatrobeads) column chromatographies. The chemical structure was characterized by fatty acid analysis, sphingoid analysis, hydrogen fluoride degradation, acid hydrolysis, enzymatic hydrolysis, infrared analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The ceramide moieties of C. intestinalis Sphingomyelin consisted primarily of C16:0, C18:0, and C18:1 fatty acids and d18:2 sphingadiene. Furthermore, Sphingomyelins were isolated and characterized from 3 other ascidians, Halocynthia roretzi, Halocynthia aurantium, and Styela clava using the same methods. Comparative analysis of the Sphingomyelin structures in 4 ascidian species-C. intestinalis (Enterogona) and H. roretzi, H. aurantium, and S. clava (Pleurogona)-revealed that the major fatty acid composition of the ceramides was similar, and that they differed in minor components.
Jeffrey A. Medin - One of the best experts on this subject based on the ideXlab platform.
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On-Tissue Localization of Ceramides and Other Sphingolipids by MALDI Mass Spectrometry Imaging
2015Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other sphingolipids. Increasingly, altered or elevated levels of sphingolipids, sphingolipid metabolites, and sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other sphingolipid metabolites accumulate in tissues, specific ceramides and Sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or Sphingomyelinase. Multiple glycosphingolipid species were also detected. The newly generated library of sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and Sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and Sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and Sphingomyelin in tissues
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on tissue localization of ceramides and other sphingolipids by maldi mass spectrometry imaging
Analytical Chemistry, 2014Co-Authors: Ellen E. Jones, Thierry Levade, Shaalee Dworski, Gemma Fabriàs, Daniel Canals, Josefina Casas, Drew Schoenling, Chadrick Denlinger, Yusuf A. Hannun, Jeffrey A. MedinAbstract:A novel MALDI-FTICR imaging mass spectrometry (MALDI-IMS) workflow is described for on-tissue detection, spatial localization, and structural confirmation of low abundance bioactive ceramides and other sphingolipids. Increasingly, altered or elevated levels of sphingolipids, sphingolipid metabolites, and sphingolipid metabolizing enzymes have been associated with a variety of disorders such as diabetes, obesity, lysosomal storage disorders, and cancer. Ceramide, which serves as a metabolic hub in sphingolipid metabolism, has been linked to cancer signaling pathways and to metabolic regulation with involvement in autophagy, cell-cycle arrest, senescence, and apoptosis. Using kidney tissues from a new Farber disease mouse model in which ceramides of all acyl chain lengths and other sphingolipid metabolites accumulate in tissues, specific ceramides and Sphingomyelins were identified by on-tissue isolation and fragmentation, coupled with an on-tissue digestion by ceramidase or Sphingomyelinase. Multiple glycosphingolipid species were also detected. The newly generated library of sphingolipid ions was then applied to MALDI-IMS of human lung cancer tissues. Multiple tumor specific ceramide and Sphingomyelin species were detected and confirmed by on-tissue enzyme digests and structural confirmation. High-resolution MALDI-IMS in combination with novel on-tissue ceramidase and Sphingomyelinase enzyme digestions makes it now possible to rapidly visualize the distribution of bioactive ceramides and Sphingomyelin in tissues.
Claude Wolf - One of the best experts on this subject based on the ideXlab platform.
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Thermotropic and structural evaluation of the interaction of natural Sphingomyelins with cholesterol.
Biochimica et Biophysica Acta, 2009Co-Authors: Peter J Quinn, Claude WolfAbstract:Abstract The structural transitions in aqueous dispersions of egg-Sphingomyelin and bovine brain-Sphingomyelin and Sphingomyelin co-dispersed with different proportions of cholesterol were compared during temperature scans between 20° and 50 °C using small-angle and wide-angle X-ray scattering techniques. The Bragg reflections observed in the small-angle scattering region from pure phospholipids and codispersions of Sphingomyelin:cholesterol in molar ratios 80:20 and 50:50 could all be deconvolved using peak fitting methods into two coexisting lamellar structures. Electron density profiles through the unit cell normal to the bilayer plane were calculated to derive bilayer and water layer thicknesses of coexisting structures at 20° and 50 °C. Codispersions of Sphingomyelin:cholesterol in a molar ratio 60:40 consisted of an apparently homogeneous bilayer structure designated as liquid-ordered phase. Curve fitting analysis of the wide-angle scattering bands were applied to correlate changes in packing arrangements of hydrocarbon in the hydrophobic domain of the bilayer with changes in enthalpy recorded by differential scanning calorimetry. At 20 °C the wide-angle scattering bands of both pure Sphingomyelins and codispersions of Sphingomyelin and cholesterol could be deconvolved into two symmetric components. A sharp component located at a d-spacing of 0.42 nm was assigned to a gel phase in which the hydrocarbon chains are oriented perpendicular to the bilayer plane. A broader symmetric band centered at d-spacings in the region of 0.44 nm was assigned as disordered hydrocarbon in dispersions of pure Sphingomyelin and as liquid-ordered phase in codispersions of Sphingomyelin and cholesterol. It is concluded from the peak fitting analysis that cholesterol is excluded from gel phases of egg and brain Sphingomyelins at 20 °C. The gel phases coexist with liquid-ordered phase comprised of egg-Sphingomyelin and 27 mol% cholesterol and brain-Sphingomyelin and 33 mol% cholesterol, respectively. Correlation of the disappearance of gel phase during heating scans and the enthalpy change recorded by calorimetry in codispersions of Sphingomyelin and cholesterol leads to the conclusion that a major contribution to the broadened phase transition endotherm originates from dilution of the cholesterol-rich liquid-ordered phase by mobilization of Sphingomyelin from the melting gel phase.
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hydrocarbon chains dominate coupling and phase coexistence in bilayers of natural phosphatidylcholines and Sphingomyelins
Biochimica et Biophysica Acta, 2009Co-Authors: Peter J Quinn, Claude WolfAbstract:The structure and thermotropic phase behaviour of aqueous dispersions of egg phosphatidylcholine, egg Sphingomyelin, bovine brain Sphingomyelin and binary mixtures of phosphatidylcholine and Sphingomyelins have been examined by synchrotron X-ray diffraction methods. Small-angle lamellar Bragg peaks and wide-angle X-ray scattering bands have been subjected to peak fitting procedures to identify coexisting gel and fluid as well as fluid–fluid bilayer structures. Molecular species of egg phosphatidylcholine exhibit fluid–fluid immiscibility throughout heating scans from 20 ° to 50 °C. Egg and brain Sphingomyelins exhibit gel–fluid bilayer coexistence at temperatures below the main phase transition temperature and fluid–fluid phase coexistence at higher temperatures. Binary mixtures of equimolar proportions of egg phosphatidylcholine and either of the Sphingomyelins show gel–fluid phase coexistence at temperatures below the gel phase transition temperature of the respective Sphingomyelin. Binary mixtures containing egg Sphingomyelin show fluid–fluid immiscibility at all temperatures of the heating scans whereas the fluid phase of mixtures comprising brain Sphingomyelin are apparently miscible at all temperatures. An analysis of binary mixtures containing egg Sphingomyelin and egg phosphatidylcholine in molar ratios 50:50, 67:33 and 83:17 at 50 °C to identify the composition of the lamellar phases indicated that the two phospholipids are immiscible in bilayers in the fluid phase. The results are discussed in terms of the role of intermolecular hydrogen bonds and hydrocarbon chain composition of Sphingomyelins in maintaining coupling across fluid bilayers.
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blood Sphingomyelins from two european countries
Biochimica et Biophysica Acta, 1995Co-Authors: Haralambos Katsikas, Claude WolfAbstract:The objectives of this study were to isolate and analyse human blood Sphingomyelins from two European populations which have significant differences in both the composition of dietary fat source and the rate of mortality from coronary heart disease. Blood samples have been taken from healthy adult volunteers from a Greek (Thessaloniki) and a French (Paris) region. The Sphingomyelin fraction from red blood cells and plasma, separately, have been isolated by thin-layer chromatography and analysed by mass spectrometry after soft chemical ionisation with gas ammonia. The conditions used gave spectra with three discrete areas which correspond to ions coming from sphingoid bases, fatty acids and ceramides. Eight sphingoid bases have been detected in both red blood cells and plasma. Sphingosine was the major contributor. The rest of the sphingoid bases have 16 to 19 carbon atoms and 0 to 2 double bonds. Fourteen fatty acids, the same for red blood cells and plasma, have been detected with 16 to 26 carbon atoms and 0 to 2 double bonds. Palmitic acid was the most abundant fatty acid. Thirty eight ceramides have been detected in red blood cells and forty in plasma. Thirty six ceramides were common in red blood cells and plasma. Statistically significant differences (P < 0.01) have been detected between the two populations for some sphingoid bases, fatty acids and ceramides. Differences have also been found between the two populations in the degree of saturation of these Sphingomyelin parts. These differences are attributed to (a) high monounsaturated fat, olive oil, consumption by Greeks and (b) other environmental and genetic factors. It is suggested that the detected differences between the two populations contribute to the different coronary heart disease rates observed among Greeks and French.
