Mobilization of xanthine oxidase from the gastrointestinal tract in acute pancreatitis

BACKGROUND: Xanthine oxidoreductase has been proposed to play a role in the development of local and systemic effects of acute pancreatitis. Under physiologic conditions, the enzyme exists mainly as xanthine dehydrogenase (XDH) but can be converted by proteolytic cleavage to its superoxide-generating form xanthine oxidase (XOD). In addition to its intracellular location XDH/XOD is also associated to the polysaccharide chains of proteoglycans on the external endothelial cell membrane. In the early stages of acute pancreatitis, this enzyme seems to be arising from its mobilization from the gastrointestinal endothelial cell surface. Taking into account the ability of α-amylase to hydrolyze the internal α-1,4 linkages of polysaccharides, we wanted to elucidate the involvement of α-amylase in XDH/XOD mobilization from the gastrointestinal endothelial cell surface and the relevance of the ascitic fluid (AF) as the source of α-amylase in experimental acute pancreatitis. METHODS: Acute pancreatitis was induced in male Wistar rats by intraductal administration of 5% sodium taurocholate. In another experimental group 3000 U/Kg α-amylase was i.v. administered. The concentrations of XDH, XOD and α-amylase in plasma and AF and myeloperoxidase (MPO) in lung have been evaluated. In additional experiments, the effect of peritoneal lavage and the absorption of α-amylase present in the AF by an isolated intestine have been determined. RESULTS: Similar increase in XDH+XOD activity in plasma was observed after induction of acute pancreatitis and after i.v. administration of α-amylase. Nevertheless, the conversion from XDH to XOD was only observed in the pancreatitis group. Lung inflammation measured as MPO activity was observed only in the pancreatitis group. In addition peritoneal lavage prevented the increase in α-amylase and XDH+XOD in plasma after induction of pancreatitis. Finally, it was observed that α-amylase is absorbed from the AF by the intestine. CONCLUSIONS: During the early stages of acute pancreatitis, α-amylase absorbed from AF through the gastrointestinal tract could interfere with the binding of XDH/XOD attached to glycoproteins of the endothelial cells. Proteolytic enzymes convert XDH into its oxidase form promoting an increase in circulating XOD that has been reported to be one of the mechanisms involved in the triggering of the systemic inflammatory process

Common variants in Alzheimer’s disease and risk stratification by polygenic risk scores

Funder: Funder: Fundación bancaria ‘La Caixa’ Number: LCF/PR/PR16/51110003 Funder: Grifols SA Number: LCF/PR/PR16/51110003 Funder: European Union/EFPIA Innovative Medicines Initiative Joint Number: 115975 Funder: JPco-fuND FP-829-029 Number: 733051061Genetic discoveries of Alzheimer's disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer's disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer's disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer's disease

Common variants in Alzheimer's disease and risk stratification by polygenic risk scores.

Funder: Funder: Fundación bancaria ‘La Caixa’ Number: LCF/PR/PR16/51110003 Funder: Grifols SA Number: LCF/PR/PR16/51110003 Funder: European Union/EFPIA Innovative Medicines Initiative Joint Number: 115975 Funder: JPco-fuND FP-829-029 Number: 733051061Genetic discoveries of Alzheimer's disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer's disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer's disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer's disease

Application of combined gas chromatography-mass spectrometry to the analysis of organic products of biogeochemical significance

A large number of organic products of diverse origins have been studied by gas chromatography and by combined gas chromatography-mass spectrometry. This combination technique allows the rigorous structural characterization of the individual compounds present in multicomponent mixtures. Its application to the determination of bioorganic lipids provides data on the biological order at the molecular level. Thus important correlations, relevant to the distributions, origins and biosynthetic pathways of the compounds, can be established. Among the lipids, the hydrocarbons and fatty acids have been the most extensively studied but in general the interest has been centered around the isoprenoid hydrocarbons because of their structural specificity and diagenetic stability. Also the characteristic bimodal distribution of the isoprenoids in natural products was found to be in line with their presumed biological origin. The correlations and distributional criteria established as a result of this investigation are based on the following observations: Microorganisms contain significant amounts of aliphatic hydrocarbons and fatty acids. Branched paraffins belonging to the iso and anteiso series have been identified in a few cases. In general, isoprenoids are absent. All of the microscopic algae analyzed contain high amounts of n-C[lowered 17] and in two instances, high molecular weight olefins (C[lowered 17]-C[lowered 33]) were found to be present in relatively high proportions. Several isomeric unsaturated isoprenoids were found in higher plants although their saturated counterparts are absent. High amounts of isoprenoids (pristane and squalene) were found in shark liver oil. The saponifiable fraction contains mainly normal unsaturated fatty acids. In general the hydrocarbons and fatty acids of all these products are unrelated in their distributions. Relatively large amounts of isoprenoids from the C[lowered 14] to C[lowered 21] as well as of n-alkanes were identified in a crude oil. The sample contains too, iso and anteiso alkanes and cycloalkanes. Paraffins, olefins, and methyl alkanes ranging from C[lowered 10] to C[lowered 33] were identified in a concentrate of tobacco smoke. The isoprenoids in this sample are mainly unsaturated. Terrestrial graphites contain n-alkanes, small amounts of methyl alkanes and isoprenoids from C[lowered 14] to C[lowered 22]. The outside parts of the graphite contain more hydrocarbons than the inner parts. The possibility of abiotic synthesis of isoprenoids has been investigated using the Fischer-Tropsch reaction between hydrogen and carbon monoxide. Although n-alkanes and methyl branched isomers have been obtained in the products of more than 50 synthesis experiments, no traces of isoprenoids are present. A detailed study of a number of hydrocarbons observed in gas chromatographic analyses of six carbonaceous chondrites has resulted in the identification of nine homologous series of isomeric alkanes in addition to the n-alkane series. Two of them show isoprenoid structures corresponding to 2,6,10-trimethyl and 2,6,10,14-tetramethyl alkanes, with members in the C[lowered 14]-C[lowered 19] and C[lowered 19]-C[lowered 21] ranges, respectively. The rest is made up of five series of monomethyl alkanes (6-,5-,4-,3-,2-methyl alkanes) and two of monocycloalkanes (cyclohexyl and cyclopentyl). An identical study of the graphite-troilite nodules of three iron meteorites yielded results qualitatively very similar to the carbonaceous chondrites. Nine homologous series have been identified mass spectrometrically: the n-alkane series (C[lowered 13] to C[lowered 26]); the 2-,3-,4-,6-methyl alkane series; the two isoprenoid series, 2,6,10-trimethyl and 2,6,10,14-tetramethyl alkanes (C[lowered 16] to C[lowered 19] and C[lowered 19] to C[lowered 21] respectively), and two series of monocycloalkanes (cyclohexyl and cyclopentyl). The internal parts of the nodules show (1) smaller amounts of hydrocarbons (from three to seven times less than the surface), and (2) an increase in the ratio of isoprenoids to normal alkanes. Isoprenoids are present in all meteoritic samples analyzed. Usually they show a major maximum at C[lowered 19] (pristane) and a secondary maximum at C[lowered 16] (methyl farnesane) with a minimum at C[lowered 17] Comparative studies of isoprenoid distributions typical of meteorites show a much greater degree of correlation with their distributions in sediments and petroleum crudes than with those produced by continuous flow Fischer-Tropsch processes.Chemistry, Department o

Thermospray and electrospray mass spectrometry of flavocoenzymes. Analysis of riboflavin sulphates from sugar beet

Thermospray (TSP) liquid chromatography mass spectrometry and electrospray (ESP) mass spectrometry were applied to the analysis of the flavocoenzymes riboflavin (Rfv), riboflavin 5'-monophosphate (FMN) and flavin adenine dinucleotide (FAD). Positive and negative ion spectra are presented. TSP spectra of Rfv and FMN were characterized by the presence of intense and characteristic fragment ions containing the flavin ring whereas in those from FAD, ions containing the adenine moiety predominate. ESP affords mainly molecular weight information as well as some indication of the number of acidic places in these molecules. Application of these techniques to the analysis of root extracts from iron-depleted sugar beet (Beta vulgaris) was instrumental in the characterization of two novel riboflavin compounds, riboflavin 3'-monosulphate (3-FMS) and riboflavin 5'-monosulphate (5-FMS), as the major flavins in roots.Peer Reviewe

Mobilization of xanthine oxidase from the gastrointestinal tract in acute pancreatitis

<p>Abstract</p> <p>Background</p> <p>Xanthine oxidoreductase has been proposed to play a role in the development of local and systemic effects of acute pancreatitis. Under physiologic conditions, the enzyme exists mainly as xanthine dehydrogenase (XDH) but can be converted by proteolytic cleavage to its superoxide-generating form xanthine oxidase (XOD). In addition to its intracellular location XDH/XOD is also associated to the polysaccharide chains of proteoglycans on the external endothelial cell membrane.</p> <p>In the early stages of acute pancreatitis, this enzyme seems to be arising from its mobilization from the gastrointestinal endothelial cell surface. Taking into account the ability of α-amylase to hydrolyze the internal α-1,4 linkages of polysaccharides, we wanted to elucidate the involvement of α-amylase in XDH/XOD mobilization from the gastrointestinal endothelial cell surface and the relevance of the ascitic fluid (AF) as the source of α-amylase in experimental acute pancreatitis.</p> <p>Methods</p> <p>Acute pancreatitis was induced in male Wistar rats by intraductal administration of 5% sodium taurocholate. In another experimental group 3000 U/Kg α-amylase was i.v. administered. The concentrations of XDH, XOD and α-amylase in plasma and AF and myeloperoxidase (MPO) in lung have been evaluated. In additional experiments, the effect of peritoneal lavage and the absorption of α-amylase present in the AF by an isolated intestine have been determined.</p> <p>Results</p> <p>Similar increase in XDH+XOD activity in plasma was observed after induction of acute pancreatitis and after i.v. administration of α-amylase. Nevertheless, the conversion from XDH to XOD was only observed in the pancreatitis group. Lung inflammation measured as MPO activity was observed only in the pancreatitis group. In addition peritoneal lavage prevented the increase in α-amylase and XDH+XOD in plasma after induction of pancreatitis. Finally, it was observed that α-amylase is absorbed from the AF by the intestine.</p> <p>Conclusions</p> <p>During the early stages of acute pancreatitis, α-amylase absorbed from AF through the gastrointestinal tract could interfere with the binding of XDH/XOD attached to glycoproteins of the endothelial cells. Proteolytic enzymes convert XDH into its oxidase form promoting an increase in circulating XOD that has been reported to be one of the mechanisms involved in the triggering of the systemic inflammatory process.</p