A discrete approach for modeling cell-matrix adhesions

During recent years the interaction between the extracellular matrix and the cytoskeleton of the cell has been object of numerous studies due to its importance in cell migration processes. These interactions are performed through protein clutches, known as focal adhesions. For migratory cells these focal adhesions along with force gener- ating processes in the cytoskeleton are responsible for the for- mation of protrusion structures like lamellipodia or filopodia. Much is known about these structures: the different proteins that conform them, the players involved in their formation or their role in cell migration. Concretely, growth-cone filopo- dia structures have attracted significant attention because of their role as cell sensors of their surrounding environment and its complex behavior. On this matter, a vast myriad of math- ematical models has been presented to explain its mechan- ical behavior. In this work, we aim to study the mechani- cal behavior of these structures through a discrete approach. This numerical model provides an individual analysis of the proteins involved including spatial distribution, interaction between them, and study of different phenomena, such as clutches unbinding or protein unfolding

Molecular dynamics simulations of iron- and aluminum-loaded serum transferrin: Protonation of tyr188 is necessary to prompt metal release

Serum transferrin (sTf) carries iron in blood serum and delivers it into cells by receptor-mediated endocytosis. The protein can also bind other metals, including aluminum. The crystal structures of the metal-free and metal-loaded protein indicate that the metal release process involves an opening of the protein. In this process, Lys206 and Lys296 lying in the proximity of each other form the dilysine pair or, so-called, dilysine trigger. It was suggested that the conformational change takes place due to variations of the protonation state of the dilysine trigger at the acidic endosomal pH. In 2003, Rinaldo and Field (Biophys. J. 85, 3485-3501) proposed that the dilysine trigger alone can not explain the opening and that the protonation of Tyr188 is required to prompt the conformational change. However, no evidence was supplied to support this hypothesis. Here, we present several 60 ns molecular dynamics simulations considering various protonation states to investigate the complexes formed by sTf with Fe(III) and Al(III). The calculations demonstrate that only in those systems where Tyr188 has been protonated does the protein undergo the conformational change and that the dilysine trigger alone does not lead to the opening. The simulations also indicate that the metal release process is a stepwise mechanism, where the hinge-bending motion is followed by the hinge-twisting step. Therefore, the study demonstrates for the first time that the protonation of Tyr188 is required for the release of metal from the metal loaded sTf and provides valuable information about the whole process

A hybrid computational model for collective cell durotaxis

Collective cell migration is regulated by a complex set of mechanical interactions and cellular mechanisms. Collective migration emerges from mechanisms occurring at single cell level, involving processes like contraction, polymerization and depolymerization, of cell–cell interactions and of cell–substrate adhesion. Here, we present a computational framework which simulates the dynamics of this emergent behavior conditioned by substrates with stiffness gradients. The computational model reproduces the cell’s ability to move toward the stiffer part of the substrate, process known as durotaxis. It combines the continuous formulation of truss elements and a particle-based approach to simulate the dynamics of cell–matrix adhesions and cell–cell interactions. Using this hybrid approach, researchers can quickly create a quantitative model to understand the regulatory role of different mechanical conditions on the dynamics of collective cell migration. Our model shows that durotaxis occurs due to the ability of cells to deform the substrate more in the part of lower stiffness than in the stiffer part. This effect explains why cell collective movement is more effective than single cell movement in stiffness gradient conditions. In addition, we numerically evaluate how gradient stiffness properties, cell monolayer size and force transmission between cells and extracellular matrix are crucial in regulating durotaxis

VARIABILIDAD EN EL REGISTRO DE ALERGIAS POR PROFESIONALES SANITARIOS EN UN HOSPITAL DE TERCER NIVEL.

Introducción: El objetivo del estudio es cuantificar el grado de coincidencia en las alergias registradas en las distintas aplicaciones informáticas disponibles para cada profesional sanitario (médicos, personal de enfermería y farmacéuticos). Métodos: Estudio observacional descriptivo retrospectivo de 3 meses de duración en el que participaron todas las Unidades Clínicas con Sistema de Distribución de Medicamentos en Dosis Unitarias. Se incluyeron a todos los pacientes ingresados con al menos una alergia registrada en cualquiera de las tres aplicaciones informáticas utilizadas por los distintos profesionales sanitarios. Se cuantificaron el porcentaje de alergias registradas en una, dos o tres aplicaciones disponibles. Resultados: Se incluyeron 767 pacientes en los que se registraron 1257 alergias. La mediana de edad fue 59 años y el 60,76% eran mujeres. El 70,09% de las alergias registradas fueron farmacológicas. El registro de alergias únicamente a través de la aplicación de enfermería fue el más frecuente (36,67%). El porcentaje de alergias registradas por los tres profesionales sanitarios fue el 7,88%. Haciendo distinción en el tipo de alergia, solamente el 0,80% de las alergias no farmacológicas fueron registradas simultáneamente por los tres profesionales sanitarios frente al 10,90% de las farmacológicas. El personal médico contribuyó al registro del 59,29% de las alergias farmacológicas y del 10,65% de las no farmacológicas. Discusión: Existe una gran variabilidad en el registro de alergias por parte del personal sanitario y escasa concordancia en las registradas por cada  tipo de profesionales. El personal médico únicamente registró una décima parte de las alergias no farmacológicas

VARIABILIDAD EN EL REGISTRO DE ALERGIAS POR PROFESIONALES SANITARIOS EN UN HOSPITAL DE TERCER NIVEL.

Introducción: El objetivo del estudio es cuantificar el grado de coincidencia en las alergias registradas en las distintas aplicaciones informáticas disponibles para cada profesional sanitario (médicos, personal de enfermería y farmacéuticos). Métodos: Estudio observacional descriptivo retrospectivo de 3 meses de duración en el que participaron todas las Unidades Clínicas con Sistema de Distribución de Medicamentos en Dosis Unitarias. Se incluyeron a todos los pacientes ingresados con al menos una alergia registrada en cualquiera de las tres aplicaciones informáticas utilizadas por los distintos profesionales sanitarios. Se cuantificaron el porcentaje de alergias registradas en una, dos o tres aplicaciones disponibles. Resultados: Se incluyeron 767 pacientes en los que se registraron 1257 alergias. La mediana de edad fue 59 años y el 60,76% eran mujeres. El 70,09% de las alergias registradas fueron farmacológicas. El registro de alergias únicamente a través de la aplicación de enfermería fue el más frecuente (36,67%). El porcentaje de alergias registradas por los tres profesionales sanitarios fue el 7,88%. Haciendo distinción en el tipo de alergia, solamente el 0,80% de las alergias no farmacológicas fueron registradas simultáneamente por los tres profesionales sanitarios frente al 10,90% de las farmacológicas. El personal médico contribuyó al registro del 59,29% de las alergias farmacológicas y del 10,65% de las no farmacológicas. Discusión: Existe una gran variabilidad en el registro de alergias por parte del personal sanitario y escasa concordancia en las registradas por cada  tipo de profesionales. El personal médico únicamente registró una décima parte de las alergias no farmacológicas

Weak Magnetic Dipole Moments in the MSSM

We calculate the weak magnetic dipole moment of different fermions in the MSSM. In particular, we consider in detail the predictions for the WMDM of the tau lepton and bottom quark. We compare the purely SUSY contributions with two Higss doublet models and SM predictions. For the tau lepton, we show that chargino diagrams give the main SUSY contribution, which for tan beta=50 can be one order of magnitude bigger than the SM prediction. For the b quark, gluino diagrams provide the main SUSY contribution to its weak anomalous dipole moment, which is still dominated by gluon contributions. We also study how the universality assumption in the slepton sector induces correlations between the SUSY contributions to the tau WMDM and to (g-2) of the muon.Comment: 17 pages, LaTex, uses psfig.sty with 6 figure

Influence of the U(1)_A Anomaly on the QCD Phase Transition

The SU(3)_{r} \times SU(3)_{\ell} linear sigma model is used to study the chiral symmetry restoring phase transition of QCD at nonzero temperature. The line of second order phase transitions separating the first order and smooth crossover regions is located in the plane of the strange and nonstrange quark masses. It is found that if the U(1)_{A} symmetry is explicitly broken by the U(1)_{A} anomaly then there is a smooth crossover to the chirally symmetric phase for physical values of the quark masses. If the U(1)_{A} anomaly is absent, then there is a phase transition provided that the \sigma meson mass is at least 600 MeV. In both cases, the region of first order phase transitions in the quark mass plane is enlarged as the mass of the \sigma meson is increased.Comment: 5 pages, 3 figures, Revtex, discussion extended and references added. To appear in PR

Highly N2-Selective Activated Carbon-Supported Pt-In Catalysts for the Reduction of Nitrites in Water

The catalytic reduction of nitrites over Pt-In catalysts supported on activated carbon has been studied in a semi-batch reactor, at room temperature and atmospheric pressure, and using hydrogen as the reducing agent. The influence of the indium content on the activity and selectivity was evaluated. Monometallic Pt catalysts are very active for nitrite reduction, but the addition of up to 1 wt% of indium significantly increases the nitrogen selectivity from 0 to 96%. The decrease in the accessible noble metal surface area reduces the amount of hydrogen available at the catalyst surface, this favoring the combination of nitrogen-containing intermediate molecules to promote the formation of N2 instead of being deeply hydrogenated into NH4+. Several activated carbon-supported Pt-In catalysts, activated under different calcination and reduction temperatures, have been also evaluated in nitrite reduction. The catalyst calcined and reduced at 400°C showed the best performance considering both the activity and the selectivity to nitrogen. This enhanced selectivity is ascribed to the formation of Pt-In alloy. The electronic properties of Pt change upon alloy formation, as it is demonstrated by XPS.This work was financially supported by Base-UIDB/50020/2020 and Programmatic-UIDP/50020/2020 Funding of LSRE-LCM, funded by natiunal funds through FCT/MCTES (PIDDAC). Financial support from Ministerio de Ciencia e Innovación (Spain, Project PID 2019-108453GB-C21 and PID 2020-116998RB-I00) is gratefully acknowledged

Determinación de la permitividad y conductividad eléctricas a la frecuencia de microondas de varios tejidos de rata tratadas con cadmio

and conductivity (s) in several rat tissue, control and treated with cadmio (Cd), applying electromagnetic fields of radiofrequency and to check if these parameters can be used as indicators of cadmium toxicity and presence in the environment in certain organs. There are used two groups of male Wistar rats, a control group and the one treated with cadmium (CdClz), with twelve single intraperitoneal increasing doses from 0,1 to 1 mg Cd/Kg rat/day. After blood extraction under ether anesthesia the animals died and several biochemical and haematological parameteres are analyzed. The dissected organs are: brain cortex, testes, kidney, liver, pancreas, Iungseand muscle, which are submitted to determine the e and o, measuring the reflection and transmission, complex coefficients of these biological samples at the industrial frequency of 2.45 GHz. This frequency is included in the range of microwave frequencies. The reflection and transmission coefficients are measured with a network analyzer. We use a HP HFSS simulator that determines the permittivity of a tissue that would produce the same values for reflection and transmission coefficients obtained experimentally. Results show that in liver and kidney there is a decrease in the e and (J compared to the controls. The changes in the kidney can be explained because the renal cortex is the major target tissue for cadmium toxicity, prqvoking proximal tubular disfunction. In liver, cadmium also accumulates inducing hepatic damage, with an increase of both transaminases in serum and the decrease of the structural integrity of hepatocytes. Blood analysis show that cadmium induces an anaemic state, with a de crease in hemoglobin and hematocrite values in comparison to thecontrols.Los campos electromagnéticos ambientales cada vez más presentes en el entorno, pueden afectar a los propios seres humanos y, según su intensidad (magnetoterapia), activar o modular procesos fisiológicos o inducir a posibles patologías. En este trabajo se pretende determinar las características fisicoquímicas (los parámetros permitividad (e) y conductividad eléctrica

Bounds on the dipole moments of the tau-neutrino via the process e+e−→ννˉγe^{+}e^{-}\rightarrow \nu \bar \nu \gamma in a 331 model

We obtain limits on the anomalous magnetic and electric dipole moments of the $\nu_{\tau}$ through the reaction $e^{+}e^{-}\rightarrow \nu \bar \nu \gamma$ and in the framework of a 331 model. We consider initial-state radiation, and neglect $W$ and photon exchange diagrams. The results are based on the data reported by the L3 Collaboration at LEP, and compare favorably with the limits obtained in other models, complementing previous studies on the dipole moments.Comment: 13 pages, 4 figures, to be published in The European Physical J C. arXiv admin note: substantial text overlap with arXiv:hep-ph/060527