Fractional diffusion models of cardiac electrical propagation: role of structural heterogeneity in dispersion of repolarization

Structural heterogeneity constitutes one of the main substrates influencing impulse propagation in living tissues. In cardiac muscle, improved understanding on its role is key to advancing our interpretation of cell-to-cell coupling, and how tissue structure modulates electrical propagation and arrhythmogenesis in the intact and diseased heart. We propose fractional diffusion models as a novel mathematical description of structurally heterogeneous excitable media, as a mean of representing the modulation of the total electric field by the secondary electrical sources associated with tissue inhomogeneities. Our results, validated against in-vivo human recordings and experimental data of different animal species, indicate that structural heterogeneity underlies many relevant characteristics of cardiac propagation, including the shortening of action potential duration along the activation pathway, and the progressive modulation by premature beats of spatial patterns of dispersion of repolarization. The proposed approach may also have important implications in other research fields involving excitable complex media

Evergreen windbreaks for Iowa farmsteads

A windbreak, as we generally think of it in Iowa, is a narrow belt of trees planted to give the farmstead protection against winter winds. Much of Iowa’s land is relatively level to gently rolling. There is little native timber except along rivers and streams. This combination permits northwesterly winter winds to make a clean sweep across the land. Something is needed to break their force

LogMap family participation in the OAEI2018

We present the participation of LogMap and its variants in the OAEI 2018 campaign. The LogMap project started in January 2011 with the objective of developing a scalable and logic-based ontology matching system. This is our eight participation in the OAEI and the experience has so far been very positive. LogMap is one of the few systems that participates in (almost) all OAEI tracks

An ontology for the conceptualization of an intelligent environment and its operation

International audienceNowadays sensors and actuators are increasingly used in different spaces, creating an intelligent environment. This article aims to describe a conceptualization of an intelligent environment and its operation, in order to check its consistency and its conformity. This conceptualization is done through an ontology representing the domain knowledge, whose elements will be instantiated from natural language texts describing the physical configuration of an intelligent environment and a scenario describing the operation desired by the user of the environment. We chose OWL to represent formally our environment augmented with SWRL rules to represent the dynamic aspect of the operation system and SQWRL to query our conceptual model. We show how consistency and conformity are checked thanks to this formalism

COA6 facilitates cytochrome c oxidase biogenesis as thiol-reductase for copper metallochaperones in mitochondria.

The mitochondrial cytochrome c oxidase, the terminal enzyme of the respiratory chain, contains heme and copper centers for electron transfer. The conserved COX2 subunit contains the CuA site, a binuclear copper center. The copper chaperones SCO1, SCO2, and COA6 are required for CuA center formation. Loss of function of these chaperones and the concomitant cytochrome c oxidase deficiency cause severe human disorders. Here we analyzed the molecular function of COA6 and the consequences of COA6 deficiency for mitochondria. Our analyses show that loss of COA6 causes combined complex I and complex IV deficiency and impacts membrane potential driven protein transport across the inner membrane. We demonstrate that COA6 acts as a thiol-reductase to reduce disulphide bridges of critical cysteine residues in SCO1 and SCO2. Cysteines within the CX3CXNH domain of SCO2 mediate its interaction with COA6 but are dispensable for SCO2-SCO1 interaction. Our analyses define COA6 as thiol-reductase, which is essential for CuA biogenesis

DIANNEXIN DOWN-MODULATES TNF-INDUCED ENDOTHELIAL MICROPARTICLE RELEASE BY BLOCKING MEMBRANE BUDDING PROCESS.

BACKGROUND: Microparticles are now recognised as true biological effectors with a role in immunopathology through their ability to disseminate functional properties. Diannexin, a homodimer of annexin V, binds to PS with a higher affinity and longer blood half-life than the monomer, inhibits prothrombinase complex activity thereby diminishing coagulation and reperfusion injury mediators and prevent microvesicle-mediated material transfer. Our aim was to determine if Diannexin could modulate microparticle production by endothelial cells by interacting with the phosphatidylserine exposure occurring during the release of these vesicles. RESULTS: In this study we showed that fluorescently labelled Diannexin binds to calcimycin-activated endothelial cells but not to resting cells. After overnight incubation, Diannexin enters cells and their released MP carry Diannexin. Some Diannexin seems to be processed via early endosomes and later is found in lysosomes. Both unlabelled Diannexin and fluorescent Diannexin inhibit MP release from TNF-activated endothelial cells. However, Diannexin treatment does not prevent endothelial activation by TNF. In addition, the inhibitory effect of Diannexin on MP release could be observed when cells were pre-, concomitantly or post-treated with cytokines. Scanning electron microscopy showed differences in the numbers and types of protuberances at the cell surface when cells were treated or not with Diannexin. Finally, there is no apparent congruency between fluorescent Diannexin labelling and surface protuberances as shown by correlative microscopy. CONCLUSIONS: Altogether these data suggest that Diannexin can inhibit endothelial vesiculation by binding PS present either at the cell surface or at the level of the inner leaflet of the plasma membrane

Un nuevo enfoque para el mejoramiento de arroz en América Latina

La crisis ocasionada por la deuda externa ha debilitado los programas nacionales de investigación de arroz en América Latina, y ha aumentado su dependencia de los programas regionales y mundiales del CIAT y del IRRI.Si bien el germoplasma mejorado producido por los IARC ha traído consigo cierto grado de uniformidad genética, también ha brindado inmensos beneficios a los programas nacionales de investigación agrícola y a los productores de arroz de la región. Estos beneficios se ven hoy en día amenazados, ya que tanto el IRRI como el CIAT, en respuesta a las presiones ejercidas por sus donantes, han comenzado a "avanzar" hacia la biotecnología, y están tratando de extrapolar el éxito que han tenido en sus programas de mejoramiento de cultivos a la compleja labor del manejo de los recursos. Una nueva estrategia para el mejoramiento del arroz en América Latina debe tener en cuenta los puntos siguientes: 1) desde el punto de vista de la diversidad genética, es conveniente abandonar el método de mejoramiento centralizado empleado por el IRRI y el CIAT; 2) el CIAT reducirá los recursos destinados al mejoramiento convencional del arroz, yse ocupará más de las biotecnologías que apoyen el mejoramiento del arroz; y 3) un plan factible (con posibilidades de éxito) debe utilizar, de manera más eficaz, los recursos humanos de los programas nacionales de investigación que hoy languidecen a causa de las restricciones económicas. Una estrategia semejante debe incluir: 1) la identificación y el establecimiento de sitios experimentales esenciales para el mejoramiento; 2) la evolución de INGER hacia una entidad cooperativa de contratación; y 3) el CIAT considerado como fuente de tecnología avanzada