Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

Platinum/ceria/alumina catalysts have been prepared by a sol–gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400°C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N2 adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86 kJ/mol has been found and at 260 °C the TOF corresponds to 0.6 ± 0.1 s−1 for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization

Unsupervised dense crowd detection by multiscale texture analysis

International audienceThis study introduces a totally unsupervised method for the detection and location of dense crowds in images without context-awareness. With the perspective of setting up fully autonomous video-surveillance systems, automatic detection and location of crowds is a crucial step that is going to point which areas of the image have to be analyzed. After retrieving multiscale texture-related feature vectors from the image, a binary classification is conducted to determine which parts of the image belong to the crowd and which to the background. The algorithm presented can be operated on images without any prior knowledge of any kind and is totally unsupervised

Kallikrein-related peptidase 5 contributes to H3N2 influenza virus infection in human lungs

Hemagglutinin (HA) of influenza virus must be activated by proteolysis before the virus can become infectious. Previous studies indicated that HA cleavage is driven by membrane-bound or extracellular serine proteases in the respiratory tract. However, there is still uncertainty as to which proteases are critical for activating HAs of seasonal influenza A viruses (IAVs) in humans. This study focuses on human KLK1 and KLK5, 2 of the 15 serine proteases known as the kallikrein-related peptidases (KLKs). We find that their mRNA expression in primary human bronchial cells is stimulated by IAV infection. Both enzymes cleaved recombinant HA from several strains of the H1 and/or H3 virus subtype in vitro, but only KLK5 promoted the infectivity of A/Puerto Rico/8/34 (H1N1) and A/Scotland/20/74 (H3N2) virions in MDCK cells. We assessed the ability of treated viruses to initiate influenza in mice. The nasal instillation of only the KLK5-treated virus resulted in weight loss and lethal outcomes. The secretion of this protease in the human lower respiratory tract is enhanced during influenza. Moreover, we show that pretreatment of airway secretions with a KLK5-selective inhibitor significantly reduced the activation of influenza A/Scotland/20/74 virions, providing further evidence of its importance. Differently, increased KLK1 secretion appeared to be associated with the recruitment of inflammatory cells in human airways regardless of the origin of inflammation. Thus, our findings point to the involvement of KLK5 in the proteolytic activation and spread of seasonal influenza viruses in humans

Expression de kallicreines tissulaires humaines dans les cancers broncho-pulmonaires non à petites cellules

Evaluation of 8 human tissue kallikrein gene expression (15 genes) in lung cancer showed that, except for KLK8, all kallikrein gene transcription resulted in synthesis of a major mRNA encoding kallikrein protein. Altogether, we identified 24 KLK transcripts in lung tissue and 11 mRNA were never described yet. We also quantified using real-time RT-PCR those KLK gene expression in normal and tumoral lung tissues Our results revealed that KLK10 and KLK11 displayed similar expression in normal and tumor lung tissues, whereas KLK5 and KLK7 differential expression was correlated with tumor histotype. KLK13 and KLK14 expression was altered in patients with or without lymph nodes metastasis. The KLK6 and KLK8 genes were highly over-expressed in NSCLC compared to normal lung tissue. Moreover, increased expression of KLK6 and KLK8 genes correlated with negative patient prognosis suggesting that proteins encoded by those genes may be involved in neo-plastic progression.L étude du transcriptome de la famille des kallicréines tissulaires (15 gènes) dans le cancer du poumon a révélé que le transcrit majoritaire produit par chacun des 8 gènes étudiés correspond à l ARNm codant la kallicréine considérée, à l exception du gène K8. Au total, 24 transcrits pulmonaires ont été identifiés dont 11 n ont jamais été décrits. Leur expression a ensuite été quantifiée par RT-PCR quantitative dans des échantillons de tissu pulmonaire tumoraux et non tumoraux adjacents. Les résultats ont révélé que l expression de K10 et K11 était peu altérée dans le poumon alors que K5 et K7 étaient différentiellement exprimés selon le type histologique de cancer et, K13 et K14 selon le degré d envahissement ganglionnaire. Enfin, les forts niveaux d expression de K6 et K8, fortement sur-exprimés dans les tissus tumoraux, constitueraient un facteur pronostique défavorable en terme de survie des patients, suggérant que hK6 et hK8 pourraient favoriser le développement tumoral.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Développement et caractérisation d'outils pour l'étude des kallicréines tissulaires humaines (application en recherche fondamentale et clinique)

TOURS-BU Médecine (372612103) / SudocSudocFranceF

Etude de l'expression du gène hKLK3 codant le PSA (Prostate-Specific Antigen), marqueur du cancer de la prostate

Le PSA codé par le gène hLK3 constitue actuellement le meilleur marqueur sanguin pour le dépistage et le suivi des tumeurs prostatiques. Des anticorps développés contre cette protéase révèlent la présence dans le sang de molécules non-engagées dans des complexes avec les inhibiteurs circulants, pourtant présents en très large excès. La nature des molécules libres étant inconnue, l'objectif de ma thèse était de vérifier si certaines de celles-ci ne correspondent pas à des produits alternatifs du gène hLK3. Après avoir montré que ce gène présente un profil d'expression complexe dans la prostate, 6 transcrits minoritaires ont été clonés et séquencés complètement. D'après l'analyse de leur séquence, ils résultent de l'utilisation de sites d'épissage et/ou de polyadénylation alternatifs et code 4 variants protéiques du PSA. Des techniques de génie génétique ont été utilisées pour produire deux de ces variants dénommés respectivement, PSA-RP1 et PSA-RP2 (PSA-Related Protein 1 et 2). Ces variants sont des protéines de sécrétion dépourvues de la sérine essentielle à liaison avec les inhibiteurs des protéases à sérine. Ils possèdent des déterminants antigéniques communs avec le PSA comme l'a démontré l'analyse immunologique effectuée avec différents anticorps anti-PSA. L'ensemble de ces observations plaide en faveur de l'appartenance de ces variants à la fraction des molécules libres circulantes. L'utilisation prochaine d'outils immunologiques spécifiques de PSA-RP1 et PSA-RP2 permettra de savoir si leur dosage pourrait améliorer le diagnostic sanguin du cancer de la prostate.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Tissue kallikrein regulates alveolar macrophage apoptosis early in influenza virus infection

International audienceHost cell proteases are involved in influenza pathogenesis. We examined the role of tissue kallikrein 1 (KLK1) by comparing wild-type (WT) and KLK1-deficient mice infected with influenza H3N2 virus. The levels of KLK1 in lung tissue and in bronchoalveolar lavage (BAL) fluid increased substantially during infection. KLK1 did not promote virus infectivity despite its trypsin-like activity, but it did decrease the initial virus load. We examined two cell types involved in the early control of pathogen infections, alveolar macrophages (AMs) and natural killer (NK) cells to learn more about the antiviral action of KLK1. Inactivating the Klk1 gene or treating WT mice with an anti-KLK1 monoclonal antibody to remove KLK1 activity accelerated the initial virus-induced apoptotic depletion of AMs. Intranasal instillation of deficient mice with recombinant KLK1 (rKLK1) reversed the phenotype. The levels of granulocyte-macrophage colony-stimulating factor in infected BAL fluid were significantly lower in KLK1-deficient mice than in WT mice. Treating lung epithelial cells with rKLK1 increased secretion of this factor known to enhance AM resistance to pathogen-induced apoptosis. The recruitment of NK cells to the air spaces peaked 3 days after infection in WT mice but not in KLK1-deficient mice, as did increases in several NK-attracting chemokines (CCL2, CCL3, CCL5, and CXCL10) in BAL. Chronic obstructive pulmonary disease (COPD) patients are highly susceptible to viral infection, and we observed that the KLK1 mRNA levels decreased with increasing COPD severity. Our findings indicate that KLK1 intervenes early in the antiviral defense modulating the severity of influenza infection. Decreased KLK1 expression in COPD patients could contribute to the worsening of influenza

Unsupervised dense crowd detection by multiscale texture analysis

International audienceThis study introduces a totally unsupervised method for the detection and location of dense crowds in images without context-awareness. With the perspective of setting up fully autonomous video-surveillance systems, automatic detection and location of crowds is a crucial step that is going to point which areas of the image have to be analyzed. After retrieving multiscale texture-related feature vectors from the image, a binary classification is conducted to determine which parts of the image belong to the crowd and which to the background. The algorithm presented can be operated on images without any prior knowledge of any kind and is totally unsupervised