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The main goal of this work is to show results obtained from a software called "Access Control by Contingency COVID-19" which allows the institution control the access to facilities after returning from COVID pandemic in order to avoid crowds of people, this software will help avoid COVID-19 infections .The methodology used for this project was Scrum ,since the development of the project required mainly a constant testing and delivery follow-up, prioritizing activities and adapting changes for greater flexibility to modifications to achieve the main objective in a established time. Currently web applications are being used as a resource in order to put together different projects, in this case health control and University access, applying a survey to generate a QR code with which people will be able to enter the university facilities, this code is read by a mobile application that sends data via wifi to a desktop application that is in charge for validating and recording student`s data, employees and external personnel accessing the institution facilities.

Vinculin is a component of focal adhesions strengthening integrin receptors association to the actin cytoskeleton during mechanotransduction. While vinculin activation leading to its association with actin filaments has been particularly studied, the role and mechanism of vinculin oligomerization remain unclear. TheShigellaIpaA effector binds to vinculin to promote efficient bacterial invasion of host cells. Unlike canonical activating ligand, IpaA interacts with the vinculin subdomains D1 and D2 via its three Vinculin Binding Sites (VBSs), promoting major allosteric changes leading to D1D2 domain-mediated trimerization. Here, we built on structural models of allosteric conformers of D1D2:IpaA complexes to design mutations and analyzed their effects on IpaA-induced trimer formation using native gel shift assays. We show that charge inversions, mutations affecting polar interactions at residues in D1D2 interfacing IpaA VBS3 and targeting a distal putative coiled-coil motif in D2 reduced the rates of D1D2 trimer formation. Introduction of these mutations in full-length vinculin led to a decrease in the number and size of focal adhesions, with distinct elongated focal adhesions associated with the coiled-coil mutation. These findings suggest that IpaA hijacks a cell endogenous head-domain mediated vinculin oligomerization process involved in the maturation of focal adhesion.

Vinculin is a protein associated to linking adhesion receptors facing the outside of cells and reinforcing them by linking it’s intracellular domain of those receptors or, in the case of Cell-Matrix adhesions, to bind to a first level adaptor protein such as talin. The structural organization of vinculin allows it to bind on one part to specific amphipathic motifs collectively designated as vinculin binding sites (VBS), to a set of different vinculin coactivators or actin regulators, and finally a domain responsible to constantly bind to F-actin in a catch bond manner. However, the ability of vinculin to effectively bind all of those intracellular partners, is highly dependent on its structural organization. Which is critically dependent on its ability to respond to mechanical tension on the molecule itself and not necessarily to its binding capacity to VBSs and complementary activators. This is recognized as the combinatorial model of activation. Nonetheless, Shigella’s IpaA effector protein is able to mimic the conformational changes associated with the ones associated with the mechanical deformation of the molecule. This model of vinculin activation is designated as the non-combinatorial model, as the presence of a single activation-partner is enough to get the same effect. This work is devoted to dig in further to develop the previous work from this lab, as we have been able to characterize thein vitroandin vivoeffects of Shigella’s IpaA-Cterm region as the one responsible for both inducing conformational changes in solution, as well as the formation of super-stable adhesion, associated to maturity markers as VASP and alpha actinin. Additionally the IpaA-Cterm transfection renders those cells with the ability to maintain the adhesion structures stable and even resist the action of actomyosin relaxing molecules. Which renders them as mechanically-independent adhesions. We found that residue substitution at the surface of D1 and D2 interphase, (as well as residues maintaining the D2 domain helical bundles folded), might participate in the maintaining the structural integrity and interdomain interaction during force dependent as revealed by its ability to form protein complexes in vitro and under force-independent settings, as the morphology of cellular adhesions is altered in a way different from the previously reported targeting only the D1-D5 interaction.

Upon activation, vinculin reinforces cytoskeletal anchorage during cell adhesion. Activating ligands classically disrupt intramolecular interactions between the vinculin head and tail domain that binds to actin filaments. Here, we show thatShigellaIpaA triggers major allosteric changes in the head domain leading to vinculin homo-oligomerization. Through the cooperative binding of its three vinculin-binding sites (VBSs), IpaA induces a striking reorientation of the D1 and D2 head subdomains associated with vinculin oligomerization. IpaA thus acts as a catalyst producing vinculin clusters that bundle actin at a distance from the activation site and trigger the formation of highly stable adhesions resisting the action of actin relaxing drugs. Unlike canonical activation, vinculin homo-oligomers induced by IpaA appear to keep a persistent imprint of the activated state in addition to their bundling activity, accounting for stable cell adhesion independent of force transduction and relevant to bacterial invasion.

Tissue engineering is crucial, since its early adoption focused on designing biocompatible materials that stimulate cell adhesion and proliferation. In this sense, scaffolds made of biocompatible and resistant materials became the researchers’ focus on biomedical applications. Humans have used essential oils for a long time to take advantage of their antifungal, insecticide, antibacterial, and antioxidant properties. However, the literature demonstrating the use of essential oils for stimulating biocompatibility in new scaffold designs is scarce. For that reason, this work describes the synthesis of four different film composites of chitosan/polyvinyl alcohol/tea tree (Melaleuca alternifolia), essential oil (CS/PVA/TTEO), and the subdermal implantations after 90 days in Wistar rats. According to the Young modulus, DSC, TGA, mechanical studies, and thermal studies, there was a reinforcement effect with the addition of TTEO. Morphology and energy-dispersive (EDX) analysis after the immersion in simulated body fluid (SBF) exhibited a light layer of calcium chloride and sodium chloride generated on the material’s surface, which is generally related to a bioactive material. Finally, the biocompatibility of the films was comparable with porcine collagen, showing better signs of resorption as the amount of TTEO was increased. These results indicate the potential application of the films in long-term biomedical needs.

The Shigella effector IpaA co-opts the focal adhesion protein vinculin to promote bacterial invasion. Here, we show that IpaA triggers an unreported mode of vinculin activation through the cooperative binding of its three vinculin-binding sites (VBSs) leading to vinculin oligomerization via its D1 and D2 head subdomains and highly stable adhesions resisting actin relaxing drugs. Using cross-linking mass spectrometry, we found that while IpaA VBSs1-2 bound to D1, IpaA VBS3 interacted with D2, a subdomain masked to other known VBSs. Structural modeling indicated that as opposed to canonical activation linked to interaction with D1, these combined VBSs interactions triggered major allosteric changes leading to D1D2 oligomerization. A cysteine-clamp preventing these changes and D1D2 oligomerization impaired growth of vinculin microclusters and cell adhesion. We propose that D1D2-mediated vinculin oligomerization occurs during the maturation of adhesion structures to enable the scaffolding of high-order vinculin complexes, and is triggered by Shigella IpaA to promote bacterial invasion in the absence of mechanotransduction.SummaryThe Shigella IpaA effector binds to cryptic vinculin sites leading to oligomerization via its head domain. This vinculin oligomerization mode appears required for the maturation and strengthening of cell adhesion but is co-opted by invasive bacteria independent of actomyosin contractility.

Currently, many strategies have been proposed to control induction motors and their physical implementations are complex systems to put into practice beyond a computer simulation. However, there are different manufacturers that provide educational modules with open systems in order to implement the proposed strategies in a practical way. The control schemes present in this educational equipment are the Scalar Control (SC) and the Field Oriented Control (FOC) being the most accurate. Although the SC is simple compared to the implementation of the FOC and others. In this work, an IFOC strategy for induction motors was implemented in educational equipment from two different manufacturers based in rotor flux vector estimation (current model). The goal of this study is to identify the advantages and disadvantages of controllers in conditions such as load changes in closed loop in a speed profile. Each controller was implemented on the same motor. Each response is analyzed and explained by graphics considering the performance at different speeds and the response to compensate changes in load.

The problem is to test the weak hypothesis of efficient markets through three neural networks that can predict the trends of investment assets such as: The Dow Jones, gold and Euro dollar, according to theories of technical analysis to automate positions of both long and short investment in the Spot market. With regard to forecasting time series, multiple approaches have been tested, through statistical models such as [1, 2, 3], where forecasts are made from different information sources with characteristics differentiated (sasonality, tendency, periodicity), however, other actors have begun to gain strength by getting the first places in international competitions, this is the case of Neural Networks, in works published as [4, 5, 6] the results have shown that this type of model offers a real opportunity to work with time series of different characteristics.

In power transmission systems faults returning leaving them offline. This problem generates an economic impact on the interested parties, partly because in certain cases transmission lines protections act in a delayed manner or because the data processing generated by electrical protections tends to be a tedious. Artificial intelligence personnel have implemented a number of methods aimed to provide solutions for detection, classification and localization of said faults. In this work, a multilayer neural network capable of performing the process of classifying 11 types of faults in power transmission lines was implemented. As a result, a graphical interface allows users to intuitively visualize the faults.

Tissue paper is of high importance worldwide and, continuously, research is focused on improvements of the softening and durability properties of the paper which depend specifically on the production process. Polyamide-amine-epichlorohydrin (PAE) resins along with release agents are widely used to adhere the paper to the yankee dryer (creping cylinder) in paper manufacture. Nevertheless, these resins are highly cationic and they normally adhere in excess to the paper which negatively affects the creping process and the quality of the paper. For this reason, a low cationic polyamine-epichlorohydrin coating (Polycoat 38&reg, ) was synthesized from a diamine supplied by Disproquin S.A.S. and epichlorohydrin. The analysis of the synthesized polymer was carried out by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR). The molecular weight of the polymer was obtained by gel permeation chromatography (GPC), physical-chemical properties such as kinematic viscosity, percentage of solids, density, charge density were measured and compared with a commercial PAE resin (Dispro620&reg, ) Thermal stability of the Polycoat 38&reg, and glass transition temperature in presence of a release agent (Disprosol 17&reg, ) were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. Finally, a peel adhesion test and an absorption durability assessment were carried out together with the evaluation of the creeping efficiency of the paper by caliber and tensile measurements in a tissue (towel paper) production plant, demonstrating a superior performance in the paper creping process as compared to some commercially available products.

Red Tilapia is one of the most consumed but perishable fish in the world. As a result, it requires preservation methods for safe consumption without affecting its organoleptic characteristics. Chitosan encapsulating essential oils have shown to be an excellent food conservation method. For that reason, we carried out the study of the protective effect on red Tilapia fillets with chitosan beads (CB) incorporated with Thymus capitatus (TCEO) essential oil at 500, 1000, and 2000 mg/L to assess the conservation of the fillets. The TCEO composition was characterized by gas chromatography-mass spectrometry (CG-MS). For the other side, CB was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), and Scanning electron microscopy (SEM). The protective effect of the beads was tested against the Gram-positive and Gram-negative bacteria growth for four weeks. The results showed an inhibition effect in Gram-positive bacteria at higher TCEO concentration (1000 and 2000 mg/L). Besides that, the pH, total volatile basic nitrogen (T-BNV-N), color, and fillet texture were evaluated as quality attributes. The results suggested that the incorporation of the CB-TCEO allowed a higher contact of the active compounds with the food surface, which reflected more excellent stability. The quality attributes of the fillets were preserved for 26 days, suggesting its uses for the treatment for perishable food.

Several biomaterials, including natural polymers, are used to increase cellular interactions as an effective way to treat bone injuries. Chitosan (CS) is one of the most studied biocompatible natural polymers. Graphene oxide (GO) is a carbon-based nanomaterial capable of imparting desired properties to the scaffolds. In the present study, CS and GO were used for scaffold preparation. CS was extracted from the mycelium of the fungus Aspergillus niger. On the other hand, GO was synthesized using an improved Hummers-Offemann method and was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Subsequently, three formulations (GO 0%, 0.5%, and 1%) were used to prepare the scaffolds by the freeze-drying technique. The scaffolds were characterized by FTIR, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), to determine their thermal stability and pore size, demonstrating that their stability increased with the increase of GO amount. Finally, the scaffolds were implanted, recollected 30 days later, and studied with an optical microscope, which evidenced the recovery of the tissue architecture and excellent biocompatibility. Hence, these results strongly suggested the inherent nature of chitosan/graphene oxide (CS/GO) scaffolds for their application in bone tissue regeneration.

The Shigella type III effector IpaA contains three binding sites for the focal adhesion protein vinculin (VBSs), which are involved in bacterial invasion of host cells. Here, we report that IpaA VBS3 unexpectedly binds to talin. The 2.5 Å resolution crystal structure of IpaA VBS3 in complex with the talin H1-H4 helices shows a tightly folded α-helical bundle, which is in contrast to the bundle unraveling upon vinculin interaction. High-affinity binding to talin H1-H4 requires a core of hydrophobic residues and electrostatic interactions conserved in talin VBS H46. Remarkably, IpaA VBS3 localizes to filopodial distal adhesions enriched in talin, but not vinculin. In addition, IpaA VBS3 binding to talin was required for filopodial adhesions and efficient capture of Shigella. These results point to the functional diversity of VBSs and support a specific role for talin binding by a subset of VBSs in the formation of filopodial adhesions.

During Shigella cell invasion, the IpaA effector targets the focal adhesion protein vinculin through three vinculin-binding sites (VBSs). Here, we report that IpaA VBS3 also binds to talin. The 2.5 Å resolution crystal structure indicates that IpaA VBS3 forms a tightly folded α-helical bundle with talin H1-H4, contrasting with bundle unraveling upon vinculin interaction. High-affinity binding of Ipa VBS3 to talin H1-H4 requires a core of hydrophobic residues conserved in vinculin binding and a pair of electrostatic interactions accounting for talin binding specificity. IpaA VBS3 does not bind to talin H1-H5 suggesting the targeting of partially activated stretched talin but not inactive talin. Consistently, IpaA VBS3 labeled filopodial and nascent adhesions and regulated their formation through talin binding. In addition, talin-binding by IpaA VBS3 was required for bacterial capture by filopodia during Shigella invasion and for the stabilization of focal adhesions in infected cells. These findings point to the functional diversity of VBSs and a critical role for talin-binding by Shigella IpaA VBS3 and possibly talin VBSs in the regulation of adhesion structures.

The actin cytoskeleton is key to the barrier function of epithelial cells, by permitting the establishment and maintenance of cell-cell junctions and cell adhesion to the basal matrix. Actin exists under monomeric and polymerized filamentous form and its polymerization following activation of nucleation promoting factors generates pushing forces, required to propel intracellular microorganisms in the host cell cytosol or for the formation of cell extensions that engulf bacteria. Actin filaments can associate with adhesion receptors at the plasma membrane via cytoskeletal linkers. Membrane anchored to actin filaments are then subjected to the retrograde flow that may pull membrane-bound bacteria inside the cell. To induce its internalization by normally non-phagocytic cells, bacteria need to establish adhesive contacts and trick the cell into apply pulling forces, and/or to generate protrusive forces that deform the membrane surrounding its contact site. In this review, we will focus on recent findings on actin cytoskeleton reorganization within epithelial cells during invasion and cell-to-cell spreading by the enteroinvasive pathogen Shigella, the causative agent of bacillary dysentery.

The role of second messengers in the diversion of cellular processes by pathogens remains poorly studied despite their importance. Among these, Ca 2+ virtually regulates all known cell processes, including cytoskeletal reorganization, inflammation, or cell death pathways. Under physiological conditions, cytosolic Ca 2+ increases are transient and oscillatory, defining the so‐called Ca 2+ code that links cell responses to specific Ca 2+ oscillatory patterns. During cell invasion, Shigella induces atypical local and global Ca 2+ signals. Here, we show that by hydrolyzing phosphatidylinositol‐(4,5)bisphosphate, the Shigella type III effector IpgD dampens inositol‐(1,4,5)trisphosphate (InsP 3 ) levels. By modifying InsP 3 dynamics and diffusion, IpgD favors the elicitation of long‐lasting local Ca 2+ signals at Shigella invasion sites and converts Shigella ‐induced global oscillatory responses into erratic responses with atypical dynamics and amplitude. Furthermore, IpgD eventually inhibits InsP 3 ‐dependent responses during prolonged infection kinetics. IpgD thus acts as a pathogen regulator of the Ca 2+ code implicated in a versatility of cell functions. Consistent with this function, IpgD prevents the Ca 2+ ‐dependent activation of calpain, thereby preserving the integrity of cell adhesion structures during the early stages of infection.

Se conoce que la mejor manera de evitar la aparición de enfermedades crónicas no transmisibles, es a través de la práctica de estilos de vida saludables. Para los clínicos es importante buscar herramientas que ayuden a motivar y acompañar a los pacientes en este desafio al cambio, por esta razón debemos conocer los modelos teóricos de cambio de comportamiento, incluyendo la forma de valorar las diversas fases o estadios y las diferentes estrategias a desarrollar para poder acompañar a nuestros pacientes en estos cambios de estilos de vida It is well known that the best way to prevent the occurrence of chronic non-communicable diseases is through healthy lifestyles. It is important for clinicians to look for tools that may help to motivate and accompany patients in this challenge for change; so, for this reason we must know the theoretical models for behavioral change, including how to assess its various phases or stages and the different strategies to be developed, in order to be able to accompany our patients in their lifestyle changing process

In the last few years, graphene oxide (GO) has gained considerable importance in scaffold preparation for tissue engineering due to the presence of functional groups that allow the interaction between the extracellular matrix and the components of the cellular membrane. The interaction between GO and chitosan (CS) can not only improve the biomechanical properties of the scaffold but also generate a synergistic effect, facilitating tissue recovery. In vivo studies on GO are scarce, therefore, biocompatibility tests on CS-GO scaffolds and bone regeneration experiments on critical size defects were carried out on Wistar rats. Scaffolds made of CS, CS-GO 0.5%, and CS-GO 1% were prepared and implanted on Wistar rats cranial bones for three months. Scaffold samples were analyzed through histochemistry and scanning electron microscopy. The analysis performed showed reabsorption of the material by phagocytic activity and new bone formation. The CS-GO 0.5% formulation gave the best performance in bone regeneration, with excellent biocompatibility. These results show the potential of this compound for tissue regeneration opening and medical applications.

Se comunica un raro caso de carcinoma de cérvix neuroendocrino. Se presenta la sintomatología comunicada en la consulta inicial, el informe del estudio anatomopatológico de la biopsia, la revisión bibliográfica, así como algunos comentarios pertinentes.

Orientador: Lucas Catão de Freitas Ferreira Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica Resumo: Este trabalho tem por objetivo abordar geometricamente os conceitos do cálculo contextualizado no tempo, começando a partir do primeiro momento em que o conceito de limite torna-se necessário com a resolução dos paradoxos de Zeno, passando pelo método da Exaustão de Eudoxo, utilizado por Arquimedes para o cálculo da área do círculo e da área delimitada por um segmento de parábola. Após este estudo prévio, abordamos o método de Fermat para encontrar máximos e mínimos, a reta tangente a uma curva e a quadratura das parábolas supreriores de Fermat, uma generalização da quadratura da parábola feita por Arquimedes, e das hipérboles superiores. Generalizamos estes métodos às curvas representadas por séries de potências. Estudamos o desenvolvimento do cálculo, independentemente, por Newton e Leibniz, e uma breve abordagem do conceito de cálculo fracionário que surge com a notação de diferencial de Leibniz, e sua aplicação na resolução do problema da tautócrona. Por m, discutimos os conceitos de limite e continuidade de uma função que surgem com Cauchy, abordando os conceitos de derivada e integral a partir destas novas denições, que são, posteriormente, reescritas em termos de epsilon's e delta's por Weierstrass Abstract: The objective of this work is to address the concepts of calculus contextualized in time, starting from the rst moment the concept of limit becomes necessary to solve Zeno's paradoxes, passing by the Eudoxus' method of exhaustion, used by Archimedes to the calculation of the area of the circle and the area enclosed by a parabola. After this preliminary study, we discuss the Fermat's method to nd maximum and minimum, the tangent to a curve and the Fermat quadrature of the higher parables, a generalization of the quadrature of the parabola is made by Archimedes and higher hyperbole. We generalize these methods for curves represented by power series. We study the development of calculus, independently, by Newton and Leibniz, and a brief approach to the concept of fractional calculus that comes up with of Leibniz deferential notation, and their application in solving the tautochrone problem. Finally, we discuss the concepts of limit and continuity of a function that arise with Cauchy, addressing the derivative and integral concepts from these new denitions, which are subsequently rewritten in terms of epsilon's and delta's by Weierstrass Doutorado Matemática Doutor em Matemática CNPQ 140674/2014-4 CAPES

Esta investigación tuvo como objetivo diseñar estrategias pedagógicas, metodológicas, didácticas, evaluativas y de formación para la adopción de un modelo de aprendizaje por competencias. Para ello se identificó el estado actual de las estrategias implementadas en los programas de formación de pregrado. En dicho estudio se realizaron entrevistas semiestructuradas, conversatorios y panel a grupos focales de docentes y directivos; encuesta a estudiantes y análisis de los diferentes programas asignatura con el objetivo de caracterizar dichas prácticas. Las conclusiones del estudio reflejan el desarrollo de una didáctica tradicional, la cual se encuentra aislada de la concepción de formación integral asumida institucionalmente.Finalmente se plantean algunas recomendaciones para que mejorar la situación pedagógica actual de la universidad como condición básica para la adopción de un modelo por competencias.

Orientador: Lucas Catão de Freitas Ferreira Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica Resumo: Estudamos existência, unicidade, dependência contínua nos dados e comportamento assint ótico de soluções globais das equações de Navier-Stokes (com n >= 3), sob condições de pequenez no dado inicial e na força externa, em um espaço de distribuições (PMa) cuja construção é baseada na transformada de Fourier. Este espaço contém funções fortemente singulares e, em particular, funções homogêneas de um certo grau cuja correspondente solução (com tais dados) é auto-similar. Além disso, mostramos a existência de uma classe de soluções que são assintoticamente auto-similar. Estudamos também a existência de soluções estacionárias pequenas e analisamos a estabilidade assintótica delas. Finalmente, são dadas condições sob as quais a solução é uma função regular para t > 0 (mesmo com dado inicial singular) e satisfaz as equações de Navier-Stokes no sentido clássico para t > 0. Esta dissertação é baseada no artigo de M. Cannone and G. Karch, Journal of Diff. Equations 197 (2) (2004) Abstract: We study existence, uniqueness, continuous dependence upon the data and asymptotic behavior of solutions for the Navier-Stokes equations (with n _ 3), under smallness conditions on the initial data and external force, in a space of distributions (PMa), whose construction is based on Fourier transform. This space contains strongly singular functions and, in particular, homogeneous functions with a certain degree whose corresponding solution (with such data) is self-similar. Moreover, the existence of a class of asymptotically self-similar solutions is proved. We also study the existence of small stationary solutions and their asymptotic stability. Finally, conditions are given for the obtained solution to be regular for t > 0 (even with singular initial data) and to satisfy the Navier-Stokes equations in the classical sense for t > 0. This master dissertation is based on the paper by M. Cannone and G. Karch, Journal of Diff. Equations 197 (2) (2004) Mestrado Matemática Mestre em Matemática

Internalization of Shigella into host epithelial cells, where the bacteria replicates and spreads to neighboring cells, requires a type 3 secretion system (T3SS) effector coined IpaA. IpaA binds directly to and activates the cytoskeletal protein vinculin after injection in the host cell cytosol, and this was previously thought to be directed by two amphipathic α-helical vinculin-binding sites (VBS) found in the C-terminal tail domain of IpaA. Here, we report a third VBS, IpaA-VBS3, that is located N-terminal to the other two VBSs of IpaA and show that one IpaA molecule can bind up to three vinculin molecules. Biochemical in vitro Shigella invasion assays and the 1.6 A crystal structure of the vinculin·IpaA-VBS3 complex showed that IpaA-VBS3 is functionally redundant with the other two IpaA-VBSs in cell invasion and in activating the latent F-actin binding functions of vinculin. Multiple VBSs in IpaA are reminiscent of talin, which harbors 11 VBSs. However, most of the talin VBSs have low affinity and are buried in helix bundles, whereas all three of the VBSs of IpaA are high affinity, readily available, and in close proximity to each other in the IpaA structure. Although deletion of IpaA-VBS3 has no detectable effects on Shigella invasion of epithelial cells, deletion of all three VBSs impaired bacterial invasion to levels found in an ipaA null mutant strain. Thus, IpaA-directed mimicry of talin in activating vinculin occurs through three high affinity VBSs that are essential for Shigella pathogenesis.

Se estudiaron las variaciones del potasio sérico (K+) y las alteraciones electrocardiográficas al infundir diferentes velocidades de K+ endovenoso en perros. Se infundió soluciones de 20, 40, 60 y 80 mEq de K+ en una hora a perros con función renal y K+ sérico normal. Se estudiaron 9 perros: tres sin hidratación previa y seis con hidratación previa. Al infundir 20 mEq/hora de K+ los animales presentaron incremento de la frecuencia cardiaca sin alteraciones del electrocardiograma. Con 40 mEq/hora hubo alteraciones en las ondas "t" y "p", y con 60 y 80 mEq/hora, alteraciones compatibles con isquemia cardiaca y taquicardia ventricular. Los perros sin hidratación tuvieron alteraciones electrocardiográficas más notorias y fatales. Dosis de 20 mEq/hora de K+, no causaron morbilidad ni mortalidad en los animales estudiados. Dosis mayores mostraron complicaciones variables que dependieron del estado de hidratación del animal, su flujo urinario y su nivel de potasio Variations in serum potassium (K+) and electrocardiographic changes at different infusion speeds of intravenous K+ were studied in dogs. Solutions of 20, 40, 60 and 80 mEq of K+ were infused in one hour to dogs with normal renal function and normal serum K+. Nine dogs were studied: three without prior hydration and six with previous hydration. Infusing 20 mEq / hour of K+ produced an increase in heart rate without changes in the electrocardiogram. With 40 mEq / hour there were changes in the "t" and "p" waves, and with 60 and 80 mEq / hour, alterations consistent with cardiac ischemia and ventricular tachycardia. Dogs without hydration had more obvious and fatal electrocardiographic changes. Doses of 20 mEq / hour of K + caused no morbidity or mortality in the animals studied. Higher doses showed various complications which depended on the hydration status of the animal, its urinary flow and potassium level

International audience; Bacterial type 2 secretion systems (T2SS), type 4 pili, and archaeal flagella assemble fibres from initially membrane-embedded pseudopilin and pilin subunits. Fibre subunits are made as precursors with positively charged N-terminal anchors, whose cleavage via the prepilin peptidase, essential for pilin membrane extraction and assembly, is followed by N-methylation of the mature (pseudo)pilin N terminus. The conserved Glu residue at position 5 (E5) of mature (pseudo)pilins is essential for assembly. Unlike T4 pilins, where E5 residue substitutions also abolish N-methylation, the E5A variant of T2SS pseudopilin PulG remains N-methylated but is affected in interaction with the T2SS component PulM. Here, biochemical and functional analyses showed that the PulM interaction defect only partly accounts for the PulG(E5A) assembly defect. First, PulG(T2A) variant, equally defective in PulM interaction, remained partially functional. Furthermore, pseudopilus assembly defect of pulG(E5A) mutant was stronger than that of the pulM deletion mutant. To understand the dominant effect of E5A mutation, we used molecular dynamics simulations of PulG(E5A), methylated PulG(WT) (MePulG(WT)), and MePulG(E5A) variant in a model membrane. These simulations pointed to a key role for an intramolecular interaction between the pseudopilin N-terminal amine and E5 to limit polar interactions with membrane phospholipids. N-methylation of the N-terminal amine further limited its interactions with phospholipid head-groups to facilitate pseudopilin membrane escape. By binding to polar residues in the conserved N-terminal region of PulG, we propose that PulM acts as chaperone to promote pseudopilin recruitment and coordinate its membrane extraction with subsequent steps of the fibre assembly process.