616 research outputs found

    Labile glycated haemoglobin and carbamylated haemoglobin are still critical points for HbA1c measurement

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    IntroductionHaemoglobin A1c (HbA1c) is a key analyte for the monitoring of glycemic balance in diabetic patients and is used for diabetes diagnosis in many countries. The potential interference of carbamylated haemoglobin (cHb) and labile glycated haemoglobin (LA1c) on HbA1c assays must remain a matter of vigilance. Such a situation has occurred in our laboratory with a kit replacement on the Bio-Rad Variantℱ II testing system, a cation-exchange high performance liquid chromatography (HPLC) system. With this method, LA1c and cHb coeluted in a same peak which may have different consequences on HbA1c values. Materials and methodsThe influence of increasing LA1c and cHb values on HbA1c results was studied with in vitro glycation and carbamylation of samples. Samples from patients with high and normal blood urea concentrations were assayed by HPLC and immunological assay. ResultsWe observed that the degree of interference greatly varied depending on the nature of the interfering Hb fractions found under the so-called “LA1c peak”. Thus, we have decided to apply a decision tree using “LA1c” thresholds depending on: (i) the retention time, (ii) the shape of the peak, (iii) other analytes, like urea. If the peak recognized as “LA1c” is mainly formed by LA1c, we consider that there is no interference until 4%. If the peak is mainly formed by cHb, we consider an interference threshold equal to 2%. ConclusionsThis situation reminds that cHb and LA1c remain critical issues in chromatography-based HbA1c assays and that adapted criteria must be set up for result interpretation

    Modulation of drug sensitivity in yeast cells by the ATP‐binding domain of human DNA topoisomerase IIα

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    Epipodophyllotoxins are effective antitumour drugs that trap eukaryotic DNA topoisomerase II in a covalent complex with DNA. Based on DNA cleavage assays, the mode of interaction of these drugs was proposed to involve amino acid residues of the catalytic site. An in vitro binding study, however, revealed two potential binding sites for etoposide within human DNA topoisomerase IIα (htopoIIα), one in the catalytic core of the enzyme and one in the ATP‐binding N‐terminal domain. Here we have tested how N‐terminal mutations that reduce the affinity of the site for etoposide or ATP affect the sensitivity of yeast cells to etoposide. Surprisingly, when introduced into full‐length enzymes, mutations that lower the drug binding capacity of the N‐terminal domain in vitro render yeast more sensitive to epipodophyllotoxins. Consistently, when the htopoIIα N‐terminal domain alone is overexpressed in the presence of yeast topoII, cells become more resistant to etoposide. Point mutations that weaken etoposide binding eliminate this resistance phenotype. We argue that the N‐terminal ATP‐binding pocket competes with the active site of the holoenzyme for binding etoposide both in cis and in trans with different outcomes, suggesting that each topoisomerase II monomer has two non‐equivalent drug‐binding site

    Apprentissage incrémental et reconnaissance d'écriture manuscrite à la volée

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    International audienceSoumission: Jeune-chercheur Mots-clés: Reconnaissance de gestes manuscrites, Evolving Fuzzy System (EFS), concept drifts, clustering incrémental, apprentissage incrémental en-ligne. Avec la multiplication des appareils intégrant des interfaces tactiles, l'interaction homme-machine tactile ou stylet s'est démocratisée. Malgré cela, aujourd'hui encore, l'interaction repose le plus souvent sur un jeu de gestes imposés par le systÚme, facilitant la reconnaissance au détriment de la flexibilité pour l'utilisateur. Il a cependant été montré par [1] qu'un utilisateur s'approprie plus facilement les gestes de commandes s'il peut les personnaliser. De nombreuses applications pourraient tirer profit d'une telle personnalisation pour offrir un interaction personnalisée plus intuitive. Dans ce contexte, l'utilisateur peut ajouter de nouveaux gestes à chaque instant de l'utilisation du systÚme il peut aussi progressivement modifier la forme de ses gestes. Pour concevoir ce type d'interaction, il est nécessaire d'utiliser un systÚme d'apprentissage évolutif capable notamment de changer sa structure à partir de trÚs peu de données pour réagir au changement de concepts (ajout de classes, modification de gestes). Les systÚmes de reconnaisse évolutif (evolving fuzzy system (EFS)) tel que les ANYA-type fuzzy system [2] ou Evolve [3] sont des approches offrant une grande capacité d'évolution de par la flexibilité de leur structure modélisée par des rÚgles d'inférences floues. Pour autant la modélisation de la détection et de la dérive des concepts n'est pas suffisamment stable dans ces systÚmes pouvant conduire à une sur ou sous création de rÚgles. Nos travaux de recherche se focalisent sur ce dernier point pour améliorer l'adaptation du systÚme aux concepts par la modification et la création des rÚgles d'inférences floues. Actuellement le systÚme Evolve s'adapte aux dérives graduelles grùce à une mise a jour des rÚgles à l'arrivée de chaque nouveau geste, mais échoue lorsqu'il doit faire face à une dérive brutale. De maniÚre générale, il est compliqué pour un systÚme de s'adapter efficacement à la fois aux dérives brutales et au dérives graduelles. Pour amorcer ce travail, nous explorons ici une nouvelle approche permettant de remettre à jour les anciennes rÚgles en symbiose avec la création de nouvelles. Nous avons dans un premier temps exploré cette piste en conservant les données d'apprentissage pour simplifier la mise en oeuvre. De meilleurs résultats sur l'adaptation aux données sont déjà observés sur des données artificielles. Une étude comparative avec d'autres approches comme [4] a été menée sur des benchmarks de référence. Dans un second temps, on souhaite s'affranchir du stockage des données d'apprentissages. Nous proposons actuellement de faire du clustering incrémental sur deux couches en parallÚle pour chacune des rÚgles. La premiÚre couche est constituée d'un cluster qui évolue au fil de l'eau comme utilisé actuellement dans Evolve (pour suivre les changement de concepts graduels) tandis que la seconde couche travail directement sur deux clusters qui évoluent incrémentalement pour anticiper au plus tÎt la détection et la modélisation d'une dérive de concept brutale (ajout d'un nouveau geste, forte déformation des gestes existants. .. .). Nous présenterons donc les problématiques sous-tendus par ce challenge ainsi que les premiers résultats obtenus

    Is the typicality of “Provence RosĂ© wines” only a matter of color?

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    Aims: Given the diversity of French dry RosĂ© wines, Provence RosĂ© producers (France) wish to evaluate the typicality of their wines in order to better identify their typical characteristics. A clear pink color is one of them but they would also like to identify some specific odors and aromas. Here, we address these issues by: (i) assessing whether the identity of Provence RosĂ© wines is perceptible by tasting and shared by professionals based on specific odors and aromas (disregarding color as indicator using black glasses), and (ii) evaluating the impact of color on Provence RosĂ© wine typicality. Methods and results: Complementary methods were used: exemplarity measurements by a panel of wine professionals, sensory evaluation by a trained expert panel, and color assessment. It was confirmed that Provence RosĂ© wine typicality is based on color because the clearest wines were found to be more typical. However, typicality in odors and aromas was also demonstrated. Using black glasses, wine professionals from Provence agreed on ‘citrus fruit’, ‘exotic fruit’ and ‘fresh floral’ odors and aromas being typical attributes of Provence RosĂ© wines. Next, when using transparent glasses, the color of the wines clearly modified the perception of exemplarity. Conclusion: There is no single sensory profile of typical Provence RosĂ© wines. Variability within the sensory profiles of this specific RosĂ© wine area was observed, but some common aromatic and visual characteristics were identified. Significance and impact of the study: These results could be used as a marketing tool to better highlight the specific intrinsic characteristics of Provence RosĂ© wines. It will now be interesting to investigate the Provence area further in order to evaluate potential sub-area specificities linked to “terroir” factors

    Features and distribution of CD8 T cells with human leukocyte antigen class I-specific receptor expression in chronic hepatitis C.: NKRs+ CD8 T cells in chronic Hepatitis C.

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    CD8(+) T cells represent a sizable component of the liver inflammatory infiltrate in chronic hepatitis C and are thought to contribute to immune-mediated tissue injury. Because chronic stimulation may promote the expression by CD8(+) T cells of distinct human leukocyte antigen class I-specific natural killer cell receptors (NKRs) susceptible to both inhibiting effector functions and promoting cell survival, we examined the distribution and characteristics of CD8(+) T cells with such receptors in chronic hepatitis C patients. NKR CD8(+) T cells were detectable in liver and peripheral blood from hepatitis C virus (HCV)-infected patients but were not major subsets. However, the frequency of NKG2A(+) CD8(+) in the liver and in a lesser extent in the peripheral blood was positively correlated to histological activity in HCV-infected patients. No such correlation was found with KIR(+) T cells in liver in HCV-infected patients and with the both NKR CD8(+) T cells in hepatitis B virus (HBV) infected patients. Circulating CD8(+) T cells expressing KIRs exhibited phenotypic features of memory T cells with exacerbated expression of the senescence marker CD57 in patients. NKG2A(+)CD8(+) T cells were committed T cells that appeared less differentiated than KIR(+)CD8(+) T cells. In HCV-infected patients, their content in perforin was low and similar to that observed in NKG2A(-)CD8(+) T cells; this scenario was not observed in healthy subjects and HBV-infected patients. Both NKG2A and KIRs could inhibit the response of HCV-specific CD8(+) T cells ex vivo. CONCLUSION: These results support the concept that an accumulation in the liver parenchyma of NKR(+)CD8(+) T cells that have functional alterations could be responsible for liver lesions. They provide novel insights into the complexity of liver-infiltrating CD8(+) T cells in chronic hepatitis C and reveal that distinct subsets of antigen-experienced CD8(+) T cells are differentially sensitive to the pervasive influence of HCV

    Dynamique paysagÚre tardiglaciaire et holocÚne dans la vallée du Loir à Pezou (Loir-et-Cher) : développements méthodologiques et premiers résultats

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    Dans la vallĂ©e du Loir, une recherche a Ă©tĂ© initiĂ©e dans le cadre d’une thĂšse de doctorat Ă  l’universitĂ© d’Angers (J. Piana, en cours). L’objectif de l’étude est de reconstituer la trajectoire paysagĂšre de la vallĂ©e du Loir au cours des derniers 15 000 ans (sous le contrĂŽle des facteurs climatiques et anthropiques qui se sont exercĂ©s Ă  l’échelle du bassin-versant) Ă  partir d’un diagnostic des formes paysagĂšres (construction et Ă©volution des lits fluviaux et de la plaine alluviale, vĂ©gĂ©tation, parcellaire, pratiques culturales
) et de l’identification des processus dynamiques qui les ont transformĂ©es et transmises (crise, rupture, hĂ©ritage, rĂ©silience
). Dans le bassin-versant moyen du Loir (secteur de Pezou), les premiers rĂ©sultats rĂ©vĂšlent un enregistrement sĂ©dimentaire fin et permettent d’entrevoir l’évolution des paysages de la vallĂ©e en relation avec les changements climatiques et les occupations humaines au cours du Tardiglaciaire et de l’HolocĂšne. Au dĂ©but de l’HolocĂšne, les paysages fluviaux hĂ©ritent de morphologies Ă  chenaux multiples mises en place durant le dernier glaciaire (WeichsĂ©lien). La transition Tardiglaciaire-HolocĂšne est marquĂ©e par une mĂ©tamorphose vers un systĂšme Ă  chenal unique et un comblement argilo-tourbeux des bras secondaires. Ce comblement se poursuit jusqu’au NĂ©olithique, pĂ©riode durant laquelle le changement de l’activitĂ© fluviale conduit Ă  une nouvelle phase d’incision et vraisemblablement Ă  une rĂ©activation des bras latĂ©raux. À l’Âge du Fer, une importante dĂ©forestation, associĂ©e Ă  la pratique de l’élevage et de l’agriculture est mise en Ă©vidence. À partir de la pĂ©riode gallo-romaine, le contrĂŽle anthropique des processus hydro-sĂ©dimentaires est croissant et conduit Ă  l’augmentation de l’érosion des versants et Ă  une forte aggradation verticale de la plaine alluviale de la vallĂ©e du Loir. Des travaux en cours visent Ă  affiner la rĂ©solution temporelle de cette variabilitĂ© paysagĂšre et Ă  spatialiser cette derniĂšre au sein de la vallĂ©e et du bassin-versant du Loir.In the Loir River valley, a research was started within a PhD thesis at Angers University (J. Piana, in progress). The study’s goal is to reconstitute the landscape trajectory of the Loir River fluvial space over the last 15.000 years (taking into account climate and anthropogenic driving factors at the level of the watershed) on the basis of the landscape forms analysis (building and evolution of river beds and alluvial plain, vegetation, cadastre, cultural practices) and identifying dynamical processes which transform and transmit those forms (crisis, rupture, heritage, resiliency
). First results, in the Middle Loir River watershed (sector of Pezou) show high-resolution fluvial records and lead to an overview of the landscape evolution of the valley in relation to climatic change and human settlements during the Lateglacial and the Holocene. At the beginning of the Holocene, fluvial landscapes inherite from a Weichselian multi-channel pattern. The Lateglacial-Holocene transition is marked by a metamorphosis to a meandering pattern and a clayey-peaty infilling of the abandoned channels. This filling runs until the Neolithic period. Then, an increased fluvial activity leads to a new incision period and probably to a reactivation of the lateral channels. From Iron Age, we observe an important deforestation, the opening of the vegetal landscape and the practice of cattle raising activity. From the Gallo-roman period, anthropogenic control on sedimentary processes is increasing and leads to slope wearing and aggradation in the alluvial plain

    Evaluation of the analytical performances of the Cobas c513 analyser for HbA1c assay

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    Introduction: Haemoglobin A1c (HbA1c) is considered to be the gold standard for the follow-up of glycaemic control in patients with diabetes mellitus and is also a diagnostic tool. Accordingly, reliable and efficient methods must be used for its quantification. Roche Diagnostics have recently adapted the Tina-quantÂź HbA1c Third Generation immunoassay on a fully dedicated analyser, the Cobas c513, which allows a high throughput of up to 400 samples per hour. The present article deals with the evaluation of the analytical performances of this system which has been recently introduced to the market. Materials and methods: Precision, comparison with two ion-exchange high-performance liquid chromatography (HPLC) methods (Variant II and D-100 systems, BioRad Laboratories) using Passing Bablok and Bland-Altman analyses, accuracy and interference of the most frequent haemoglobin (Hb) variants on HbA1c measurement were evaluated. Results: Precision was high, with coefficients of variation lower than 1.1% (HbA1c values expressed in National Glycohemoglobin Standardization Program units, 1.7% for values expressed in International Federation of Clinical Chemistry and Laboratory Medicine [IFCC] units). The comparison study showed similar results with the two HPLC systems. The analysis of samples with IFCC-assigned values showed high methodological accuracy. Finally, no interference of bilirubin, triglycerides and common Hb variants (Hb AC, AD, AE, AS) was observed. Conclusions: This evaluation showed that the analytical performance of the Cobas c513 analyser for HbA1c assay makes it suitable for a routine use in clinical chemistry laboratories

    Complete Genome Sequence of the Piezophilic, Mesophilic, Sulfate-Reducing Bacterium Desulfovibrio hydrothermalis AM13(T.).

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    International audienceDesulfovibrio hydrothermalis AM13(T) is a piezophilic, mesophilic, hydrogenotrophic sulfate-reducing bacterium collected from a deep-sea hydrothermal chimney on the East Pacific Rise (2,600 m depth, 13°N). We report the genome sequence of this bacterium, which includes a 3,702,934-bp chromosome and a circular plasmid of 5,328 bp
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