What can EMU countries' sovereign bond spreads tell us about market perceptions of default probabilities during the recent financial crisis?

This paper presents a new approach to analysing recent movements of EMU sovereign bond spreads. Based on a GARCH-in-mean model originally used in the exchange rate target zone literature, spreads are decomposed into a risk premium, an expected loss component and a liquidity premium. Time-varying probabilities of default are derived. The results suggest that the rise in sovereign spreads during the recent financial crisis mainly reflects an increased expected loss component. In addition, the rescue of Bear Stearns in March 2008 seems to mark a change in market perceptions of sovereign bond risk. The government bonds of some countries lost their former role as a safe haven. While price competitiveness always helps to explain sovereign spreads, it increasingly moved into investors’ focus as financial sector soundness weakened.Liquidity (Economics) ; Default (Finance) ; Bonds - Prices

Milk sugars beyond lactose : metabolic fate of neutral milk oligosaccharides in infants

Free oligosaccharides in human milk (HMO) are complex carbohydrates structurally based on lactose and present at concentrations of 5–20 g/L. They are considered to be resistant to digestion in the breastfed infant’s stomach and small intestine, and to serve as energy source selectively for beneficial microbiota in the bowel. Apart from this prebiotic effect, HMO have been found to exert various biological activities in numerous in vitro studies, that indicate not only local functionality in the gut, but also, e.g. immunomodulatory or anti-infective, effects within the body. However, a direct link between structure and function in vivo has not yet been provided. This, in turn, is due to the enormous structural diversity of HMO: More than 150 different structures have been characterized to date. In this work, the metabolic pathways and excretion profiles of HMO were investigated in vivo to extend our knowledge on the sites of HMO utilization or modification and thereby to provide hints on the structure-function relationship of HMO in the infant. Therefore, a platform based on solid phase extraction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for a high throughput-profiling of oligosaccharides from human milk, infants’ urine and feces was established, complemented by isomer separation via liquid chromatography. It was used to follow the time course and possible metabolites of 13C-enriched and non-enriched oligosaccharides in milk and infant urine from ten mother-infant pairs during 36 hours after the application of 13C-galactose to the mothers. Intestinal absorption and subsequent renal excretion of intact structures, in particular (fucosylated) hexaoses, could be deduced for all infants. However, in some infants, excretion was delayed, pointing at a longer gut passage or systemic circulation of those certain structures. Moreover, structure-specific modifications and utilization in the upper parts of the gut, where absorption is thought to take place, were hypothesized. The overall oligosaccharide profiles in the feces of breastfed infants could be categorized into three groups, i.e. i) high diversity with many HMO-like structures, ii) only one or a few oligosaccharides with rather low signal intensity, and iii) no HMO. The patterns showed some association with the infants’ age. However, further research is needed to investigate the underlying causes, e.g. gut maturity or stool frequency. Novel metabolites were identified in both, infant urine and feces. They could be characterized as acetylated HMO or HMO degradation/modification products, generated by the infants or by their gut microbiota, such as secretor- or Lewis-specific HMO in the feces/urine of infants fed nonsecretor or Lewis-negative milk. Lacto-N-tetraose as a major oligosaccharide in milk was significantly reduced especially in fecal samples. Moreover, the secretor-specific structure lacto-N-fucopentaose I, which is highly abundant in secretor milk, was not detected in the urine of the infants fed Lewis b secretor milk, which indicates a selective utilization of this specific structure.Humanmilch enthält eine Vielzahl an komplexen Kohlenhydraten, die sich biosynthetisch von dem Milchzucker Laktose ableiten. Ihre Konzentrationen betragen mit ca. 5–20 Gramm pro Liter etwa ein Zehntel des Gehalts von Laktose. Bisher wurden zahlreiche biologische Effekte von Humanmilcholigosacchariden (HMO) anhand von Ergebnissen aus in vitro Studien beschrieben. Sie sollen u.a. präbiotisch und antiinfektiös im Darm des gestillten Säuglings wirken. Darüber hinaus könnten sie auch immunmodulierende und andere positive Eigenschaften im Körper haben, sofern die aktiven Substanzen im Dünndarm absorbiert werden. Um den endgültigen Beweis für die Wirksamkeit der einzelnen Substanzen beim Säugling in vivo zu erbringen, wären Interventionsstudien mit Einzelsubstanzen notwendig. Diese sind aufgrund mangelnder Verfügbarkeit synthetischer HMO bislang nicht möglich. Daher wurden in der vorliegenden Arbeit der Metabolismus und die möglichen Ausscheidungswege von HMO direkt beim gestillten Säugling untersucht, um so Hinweise auf deren Struktur-Funktionsbeziehungen in vivo zu erhalten. Dafür wurde eine analytische Plattform entwickelt, die eine effiziente und zuverlässige Identifizierung von Oligosacchariden aus Muttermilch, Säuglingsurin und –fäzes ermöglicht. In Kapitel 1 der vorliegenden Arbeit werden die aktuellen Kenntnisse zum Metabolismus und der Funktion von HMO sowie die gängigsten Methoden der Glykananalytik anhand von Literatur vorgestellt. Kapitel 2 verdeutlicht die große Relevanz der modernen Glykananalytik für die Erforschung der Struktur-Funktionsbeziehungen von HMO mit Fokus auf spezifische HMO-Strukturen mit Lewis- oder Sekretorepitopen (genetisch determinierte Blutgruppenantigene in Humanmilch). Kapitel 3 beschreibt die praktischen Studien zum Zeitverlauf der HMO-Ausscheidung im Säuglingsurin 36 Stunden nach Einzelgabe von 13C-Galaktose an die Mütter. Mittels Matrix-unterstützter Laser Desorption/Ionizations-Massenspektrometrie mit Flugzeitanalysator (MALDI-TOF-MS) wurden bei allen zehn Säuglingen intakte, auch sehr komplexe HMO detektiert. Allerdings war die Exkretion bestimmter Strukturen bei manchen Kindern verzögert, was auf eine individuell längere Darmpassage oder Blutzirkulation dieser hinweist. Des Weiteren gab es Hinweise auf eine unerwartet frühe Metabolisierung bestimmter Strukturen in oberen Darmabschnitten. Die möglichen Metaboliten nach ihrem Abbau oder Modifikation und/oder Aufnahme im Darm wurden bei derselben Probandengruppe mittels MALDI-TOF-MS und Flüssigchromatographie untersucht (Kapitel 4). Diese konnten mittels Tandem-MS als acetylierte HMO oder verschiedene HMO-Abbauprodukte charakterisiert werden, zusätzlich zu HMO-Strukturen, die offenbar erst nach der Aufnahme von den Enzymen des Kindes mit Lewis- und/oder Sekretorepitopen versehen worden waren. Einige Hinweise auf strukturspezifische Utilisation im Darm oder Organismus des Säuglings wurden darüber hinaus erlangt, beispielsweise aufgrund stark verminderter Ausscheidung von Lakto-N-tetraose im Stuhl oder Lacto-N-fukopentaose I im Urin. Die Oligosaccharidmuster von weiteren 24 Säuglingen wurden ebenfalls mittels MALDI-TOF-MS untersucht (Kapitel 5). Dabei wurden drei Untergruppen anhand der HMO-Muster im Stuhl der gestillten Säuglinge im Alter von sechs Wochen beobachtet: i) hohe Diversität an Oligosaccharidstrukturen mit Dominanz von intakten HMO, ii) wenige Oligosaccharide mit eher niedriger Signalintensität und iii) keine HMO oder HMO-Metaboliten. Im Alter von sechs Monaten wurden bei den gestillten Säuglingen keine oder sehr wenige HMO(Metaboliten) detektiert. Des Weiteren konnten bei den formelernährten und bei zwei von drei gemischt ernährten Säuglingen keine Oligosaccharide im Stuhl detektiert werden. In Kapitel 6 werden die neuen Erkenntnisse auf der Basis vorhandener Literatur abschließend diskutiert und es werden Perspektiven für künftige Humanstudien über HMO aufgezeigt

Histo-blood group glycans in the context of personalized medicine

General significance: Histo-blood group glycans have a unique linking position in the complex network of genes, oncodevelopmental biological processes, and disease mechanisms. Thus, they are highly promising targets for novel approaches in the field of personalized medicine. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc. (C) 2015 Elsevier B.V. All rights reserved.Proteomic

O- and N-glycosylation of serum immunoglobulin A is associated with IgA nephropathy and glomerular function.

BACKGROUND: IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and is a leading cause of renal failure. The disease mechanisms are not completely understood, but a higher abundance of galactose-deficient IgA is recognized to play a crucial role in IgAN pathogenesis. Although both types of human IgA (IgA1 and IgA2) have several N-glycans as post-translational modification, only IgA1 features extensive hinge-region O-glycosylation. IgA1 galactose deficiency on the O-glycans is commonly detected by a lectin-based method. To date, limited detail is known about IgA O- and N-glycosylation in IgAN. METHODS: To gain insights into the complex O- and N-glycosylation of serum IgA1 and IgA2 in IgAN, we used liquid chromatography-mass spectrometry (LC-MS) for the analysis of tryptic glycopeptides of serum IgA from 83 patients with IgAN and 244 age- and sex-matched healthy controls. RESULTS: Multiple structural features of N-glycosylation of IgA1 and IgA2 were associated with IgAN and glomerular function in our cross-sectional study. These features included differences in galactosylation, sialylation, bisection, fucosylation, and N-glycan complexity. Moreover, IgA1 O-glycan sialylation was associated with both the disease and glomerular function. Finally, glycopeptides were a better predictor of IgAN and glomerular function than galactose-deficient IgA1 levels measured by lectin-based ELISA. CONCLUSIONS: Our high-resolution data suggest that IgA O- and N-glycopeptides are promising targets for future investigations on the pathophysiology of IgAN and as potential noninvasive biomarkers for disease prediction and deteriorating kidney function

Comparative Glycomics of Immunoglobulin A and G From Saliva and Plasma Reveals Biomarker Potential

Proteomic

Comparative Glycomics of Immunoglobulin A and G From Saliva and Plasma Reveals Biomarker Potential

The N-glycosylation of immunoglobulin (Ig) G, the major antibody in the circulation of human adults, is well known for its influence on antibody effector functions and its alterations with various diseases. In contrast, knowledge on the role of glycans attached to IgA, which is a key immune defense agent in secretions, is very scarce. In this study we aimed to characterize the glycosylation of salivary (secretory) IgA, including the IgA joining chain (JC), and secretory component (SC) and to compare IgA and IgG glycosylation between human plasma and saliva samples to gain a first insight into oral cavity-specific antibody glycosylation. Plasma and whole saliva were collected from 19 healthy volunteers within a 2-h time window. IgG and IgA were affinity-purified from the two biofluids, followed by tryptic digestion and nanoLC-ESI-QTOF-MS(/MS) analysis. Saliva-derived IgG exhibited a slightly lower galactosylation and sialylation as compared to plasma-derived IgG. Glycosylation of IgA1, IgA2, and the JC showed substantial differences between the biofluids, with salivary proteins exhibiting a higher bisection, and lower galactosylation and sialylation as compared to plasma-derived IgA and JC. Additionally, all seven N-glycosylation sites, characterized on the SC of secretory IgA in saliva, carried highly fucosylated and fully galactosylated diantennary N-glycans. This study lays the basis for future research into the functional role of salivary Ig glycosylation as well as its biomarker potential

Glycan and protein analysis of glycoengineered bacterial E. coli vaccines by MALDI-in-source decay FT-ICR mass spectrometry

Bacterial glycoconjugate vaccines have a major role in preventing microbial infections. Immunogenic bacterial glycans, suchas O-antigen polysaccharides, can be recombinantly expressed and combined with specific carrier proteins to produce effective vaccines. O-Antigen polysaccharides are typically polydisperse, and carrier proteins can have multiple glycosylation sites. Consequently, recombinant glycoconjugate vaccines have a high structural heterogeneity, making their characterization challenging. Sincedevelopment and quality control processes rely on such character-ization, novel strategies are needed for faster and informative analysis.Here, we present a novel approach employing minimal samplepreparation and ultrahigh-resolution mass spectrometry analysis forprotein terminal sequencing and characterization of the oligosaccharide repeat units of bacterial glycoconjugate vaccines. Threeglycoconjugate vaccine candidates, obtained from the bioconjugation of the O-antigen polysaccharides fromE. coliserotypes O2,O6A, and O25B with the genetically detoxified exotoxin A fromPseudomonas aeruginosa, were analyzed by MALDI-in-source decay(ISD) FT-ICR MS. Protein and glycan ISD fragment ions were selectively detected using 1,5-diaminonaphtalene and a 2,5-dihydroxybenzoic acid/2-hydroxy-5-methoxybenzoic acid mixture (super-DHB) as a MALDI matrix, respectively. The analysis of protein fragments required the absence of salts in the samples, while the presence of salt was key for the detection of sodiated glycanfragments. MS/MS analysis of O-antigen ISD fragments allowed for the detection of specific repeat unit signatures. The developed strategy requires minute sample amounts, avoids the use of chemical derivatizations, and comes with minimal hands-on time allowing for fast corroboration of key structural features of bacterial glycoconjugate vaccines during early- and late-stage developmentProteomic

IgG N-glycans are associated with prevalent and incident complications of type 2 diabetes

Aims/Hypothesis:Inflammation is important in the development of type 2 diabetes complications. The N-glycosylation of IgG influences its role in inflammation. To date, the association of plasma IgG N-glycosylation with type 2 diabetes complications has not been extensively investigated. We hypothesised that N-glycosylation of IgG may be related to the development of complications of type 2 diabetes. Methods: In three independent type 2 diabetes cohorts, plasma IgG N-glycosylation was measured using ultra performance liquid chromatography (DiaGene n = 1815, GenodiabMar n = 640) and mass spectrometry (Hoorn Diabetes Care Study n = 1266). We investigated the associations of IgG N-glycosylation (fucosylation, galactosylation, sialylation and bisection) with incident and prevalent nephropathy, retinopathy and macrovascular disease using Cox- and logistic regression, followed by meta-analyses. The models were adjusted for age and sex and additionally for clinical risk factors. Results: IgG galactosylation was negatively associated with prevalent and incident nephropathy and macrovascular disease after adjustment for clinical risk factors. Sialylation was negatively associated with incident diabetic nephropathy after adjustment for clinical risk factors. For incident retinopathy, similar associations were found for galactosylation, adjusted for age and sex. Conclusions: We showed that IgG N-glycosylation, particularly galactosylation and to a lesser extent sialylation, is associated with a higher prevalence and future development of macro- and microvascular complications of diabetes. These findings indicate the predictive potential of IgG N-glycosylation in diabetes complications and should be analysed further in additional large cohorts to obtain the power to solidify these conclusions.</p

Large-scale analysis of apolipoprotein CIII glycosylation by ultrahigh resolution mass spectrometry

Apolipoprotein-CIII (apo-CIII) is a glycoprotein involved in lipid metabolism and its levels are associated with cardiovascular disease risk. Apo-CIII sialylation is associated with improved plasma triglyceride levels and its glycosylation may have an effect on the clearance of triglyceride-rich lipoproteins by directing these particles to different metabolic pathways. Large-scale sample cohort studies are required to fully elucidate the role of apo-CIII glycosylation in lipid metabolism and associated cardiovascular disease. In this study, we revisited a high-throughput workflow for the analysis of intact apo-CIII by ultrahigh-resolution MALDI FT-ICR MS. The workflow includes a chemical oxidation step to reduce methionine oxidation heterogeneity and spectrum complexity. Sinapinic acid matrix was used to minimize the loss of sialic acids upon MALDI. MassyTools software was used to standardize and automate MS data processing and quality control. This method was applied on 771 plasma samples from individuals without diabetes allowing for an evaluation of the expression levels of apo-CIII glycoforms against a panel of lipid biomarkers demonstrating the validity of the method. Our study supports the hypothesis that triglyceride clearance may be regulated, or at least strongly influenced by apo-CIII sialylation. Interestingly, the association of apo-CIII glycoforms with triglyceride levels was found to be largely independent of body mass index. Due to its precision and throughput, the new workflow will allow studying the role of apo-CIII in the regulation of lipid metabolism in various disease settings.Proteomic