El naufragi del bergantí L'Assomption: Blanes, 13 i 14 de gener de 1787

El naufragi de L’Assomption, un bergantí francès, a la platja de Blanes, el gener de 1787, és una il·lustrativa mostra d’un dilema: el rescat de la càrrega o l’adopció de mesures sanitàries per evitar epidèmies. Dues administracions diferents regien aquests afers: la jurisdicció de Marina i la Junta de Sanitat. La corrupció del poder local portà a què fos la Junta de Sanitat la competent en l’afer. La solució final explica l’origen del viceconsolat francès de Blanes

Large Diameter of Palytoxin-induced Na/K Pump Channels and Modulation of Palytoxin Interaction by Na/K Pump Ligands

Palytoxin binds to Na/K pumps to generate nonselective cation channels whose pore likely comprises at least part of the pump's ion translocation pathway. We systematically analyzed palytoxin's interactions with native human Na/K pumps in outside-out patches from HEK293 cells over a broad range of ionic and nucleotide conditions, and with or without cardiotonic steroids. With 5 mM internal (pipette) [MgATP], palytoxin activated the conductance with an apparent affinity that was highest for Na+-containing (K+-free) external and internal solutions, lowest for K+-containing (Na+-free) external and internal solutions, and intermediate for the mixed external Na+/internal K+, and external K+/internal Na+ conditions; with Na+ solutions and MgATP, the mean dwell time of palytoxin on the Na/K pump was about one day. With Na+ solutions, the apparent affinity for palytoxin action was low after equilibration of patches with nucleotide-free pipette solution. That apparent affinity was increased in two phases as the equilibrating [MgATP] was raised over the submicromolar, and submillimolar, ranges, but was increased by pipette MgAMPPNP in a single phase, over the submillimolar range; the apparent affinity at saturating [MgAMPPNP] remained ∼30-fold lower than at saturating [MgATP]. After palytoxin washout, the conductance decay that reflects palytoxin unbinding was accelerated by cardiotonic steroid. When Na/K pumps were preincubated with cardiotonic steroid, subsequent activation of palytoxin-induced conductance was greatly slowed, even after washout of the cardiotonic steroid, but activation could still be accelerated by increasing palytoxin concentration. These results indicate that palytoxin and a cardiotonic steroid can simultaneously occupy the same Na/K pump, each destabilizing the other. The palytoxin-induced channels were permeable to several large organic cations, including N-methyl-d-glucamine+, suggesting that the narrowest section of the pore must be ∼7.5 Å wide. Enhanced understanding of palytoxin action now allows its use for examining the structures and mechanisms of the gates that occlude/deocclude transported ions during the normal Na/K pump cycle

STED imaging performance estimation by means of Fourier transform analysis

Due to relatively high powers used in STED, biological samples may be affected by the illumination in the process of image acquisition. Similarly, the performance of the system may be limited by the sample itself. Optimization of the STED parameters taking into account the sample itself is therefore a complex task as there is no clear methodology that can determine the image improvement in an objective and quantitative manner. In this work, a method based on Fourier transform formalism is presented to analyze the performance of a STED system. The spatial frequency distribution of pairs of confocal and STED images are compared to obtain an objective parameter, the Azimuth Averaged Spectral Content Spread (AASCS), that is related to the performance of the system in which the sample is also considered. The method has been first tested on samples of beads, and then applied to cell samples labeled with multiple fluorescent dyes. The results show that a single parameter, the AASCS, can be used to determine the optimal settings for STED image acquisition in an objective way, only by using the information provided by the images from the sample themselves. The AASCS also helps minimize the depletion power, for better preservation of the samples.Peer ReviewedPostprint (published version

Contribución a la marca país a través de la sostenibilidad de los procesos productivos en Chile: Empresas B Corp

this article aims to demonstrate the existence of companies that contribute to the country brand by incorporating sustainable mechanismsinto their processes, while generating profits and social value. The research was carried out using a mixed methodology and naturalisticmethod in five phases. 425 companies in Chile were analyzed, using the Corp B directory in Latin America and the Caribbean. The main findingsreveal that the global pandemic and economic situation has prompted the adoption of the B Corporation model, focusing on social welfare,economic growth, and preservation of natural resources. This study highlights the contribution of B Corps to the country brand in Chile. Theseorganizations are recognized for their commitment to sustainability, their social impact, and their ability to project the country’s image globally.Their innovative and responsible business practices make them key agents for sustainable development. The scope has been limited to the Chileancontext, which could restrict extrapolation to other geographical areas, with the existence of 4,000 companies with B Corp certification internationally.The results contribute knowledge to the administrative and social sciences, providing an understanding of how they generate value to thesustainability trilogy and in turn contribute to the country brand, which can serve as the basis for future studies and business strategies.el objetivo de este artículo es evidenciar la existencia de empresas que contribuyen a la marca país mediante la incorporación de mecanismos sostenibles en sus procesos, a la vez que generan utilidades y valor social. La investigación se realizó mediante una metodología mixta y método naturalista en cinco fases. Se analizaron 425 empresas en Chile, utilizando el directorio de la Corp B en América Latina y el Caribe. Los principales hallazgos revelan que la pandemia mundial y la situación económica han impulsado la adopción del modelo de Corporación B, enfocando en el bienestar social, crecimiento económico y preservación de recursos naturales. Este estudio destaca la contribución de las empresas B a la marca país en Chile. Estas organizaciones son reconocidas por su compromiso con la sustentabilidad, su impacto social y su capacidad para proyectar la imagen país a nivel global. Sus prácticas empresariales innovadoras y responsables las convierten en agentes clave para el desarrollo sostenible. El alcance se ha limitado al contexto chileno, lo que podría restringir la extrapolación a otras áreas geográficas, con la existencia de 4000 empresas con certificación B Corp a nivel internacional. Los resultados aportan conocimiento a las ciencias administrativas y sociales, proporcionando una comprensión de cómo estas generan valor a la trilogía de sostenibilidad y su vez contribuir a la marca país, lo que puede servir de base para futuros estudios y estrategias empresariales

Sub-diffraction discrimination with polarization-resolved two-photon excited fluorescence microscopy

Imaging molecular structures separated by distances of a few nanometers still represents a complex challenge. Moreover, it is normally restricted to observations on thin (few micrometers) samples. In this work, we rotate the polarization of the excitation beam of two-photon excited fluorescence (TPEF) images to show that fluorescent structures at the molecular scale can be discriminated in a living organism. The polarization rotation generates a modulation of the signal intensity in each pixel of the TPEF images that carry information related to the fluorophore orientation. We analyze the signal modulation in every pixel of the polarization-resolved (PR) TPEF images through a Fourier analysis and generate images for the different Fourier components. Doing that, we show that two fluorophores oriented in different directions can be distinguished. Although by imaging the Fourier components the resolution of the optical system restricts the exact localization of two close molecules, discrimination is still possible even when the molecules are located at sub-diffraction distances. We propose a model that predicts this behavior, and demonstrate it experimentally in the neurons of a living Caenorhabditis elegans nematode, where we distinguish the walls of an axon with a diameter below the objective resolution. Since the technique is based in TPEF, the method can be extended to deep tissue imaging and has potential applications in single molecule detection, biological sensors, or super-resolution imaging techniques.Peer ReviewedPostprint (published version

West Nile virus in Spain: Forecasting the geographical distribution of risky areas with an ecological niche modelling approach

West Nile virus (WNV), a well-known emerging vector-borne arbovirus with a zoonotic life cycle, represents a threat to both public and animal health. Transmitted by ornithophilic mosquitoes, its transmission is difficult to predict and even more difficult to prevent. The massive and unprecedented number of human cases and equid outbreaks in Spain during 2020 interpellates for new approaches. For the first time, we present an integrate analysis from a niche perspective to provide an insight to the situation of West Nile disease (WND) in Spain. Our modelling approach benefits from the combined use of global occurrence records of outbreaks of WND in equids and of its two alleged main vectors in Spain, Culex pipiens and Cx. perexiguus. Maps of the climatic suitability for the presence of the two vectors species and for the circulation of WNV are provided. The main outcome of our study is a map delineating the areas under certain climatic risk of transmission. Our analyses indicate that the climatic risk of transmission of WND is medium in areas nearby the south Atlantic coastal area of the Cadiz Gulf and the Mediterranean coast, and high in southwestern Spain. The higher risk of transmission in the basins of the rivers Guadiana and Guadalquivir cannot be attributed exclusively to the local abundance of Cx. pipiens, but could be ascribed to the presence and abundance of Cx. perexiguus. Furthermore, this integrated analysis suggests that the WNV presents an ecological niche of its own, not fully overlapping the ones of its hosts or vector, and thus requiring particular environmental conditions to succeed in its infection cycle.Fil: Cuervo Bustamante, Pablo Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentina. Universidad de Valencia; EspañaFil: Artigas, Patricio. Universidad de Valencia; EspañaFil: Mas-Coma, Santiago. Universidad de Valencia; EspañaFil: Bargues, María Dolores. Universidad de Valencia; Españ

Control digital con FPGA de un convertidor de potencia Buck síncrono

En el presente trabajo fin de grado se busca desarrollar un diseño el cual pueda ser utilizado los próximos años en las prácticas impartidas en la rama de la Electrónica Digital y de Potencia. Se va a realizar un reductor síncrono de potencia, Buck, siendo este controlado mediante una FPGA, el proyecto aborda desde el diseño de la placa de circuito impreso, hasta todo el diseño del control digital con el fin de ser capaces de controlar la tensión de salida de este convertidor.<br /

Sodium flux ratio in Na/K pump-channels opened by palytoxin

© 2007 Rakowski et al. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License. The definitive version was published in Journal of General Physiology 130 (2007): 41-54, doi:10.1085/jgp.200709770.Palytoxin binds to Na+/K+ pumps in the plasma membrane of animal cells and opens an electrodiffusive cation pathway through the pumps. We investigated properties of the palytoxin-opened channels by recording macroscopic and microscopic currents in cell bodies of neurons from the giant fiber lobe, and by simultaneously measuring net current and 22Na+ efflux in voltage-clamped, internally dialyzed giant axons of the squid Loligo pealei. The conductance of single palytoxin-bound "pump-channels" in outside-out patches was ~7 pS in symmetrical 500 mM [Na+], comparable to findings in other cells. In these high-[Na+], K+-free solutions, with 5 mM cytoplasmic [ATP], the K0.5 for palytoxin action was ~70 pM. The pump-channels were ~40–50 times less permeable to N-methyl-D-glucamine (NMG+) than to Na+. The reversal potential of palytoxin-elicited current under biionic conditions, with the same concentration of a different permeant cation on each side of the membrane, was independent of the concentration of those ions over the range 55–550 mM. In giant axons, the Ussing flux ratio exponent (n') for Na+ movements through palytoxin-bound pump-channels, over a 100–400 mM range of external [Na+] and 0 to –40 mV range of membrane potentials, averaged 1.05 ± 0.02 (n = 28). These findings are consistent with occupancy of palytoxin-bound Na+/K+ pump-channels either by a single Na+ ion or by two Na+ ions as might be anticipated from other work; idiosyncratic constraints are needed if the two Na+ ions occupy a single-file pore, but not if they occupy side-by-side binding sites, as observed in related structures, and if only one of the sites is readily accessible from both sides of the membrane.This work was supported by NIH grants NS22979, NS11223, and HL36783, and National Science Foundation grant CCF- 0622158. This research was also partially funded by the Intra mural Research Program of the NIH, National Institute of Neurological Disorders and Stroke

Importance of the Voltage Dependence of Cardiac Na/K ATPase Isozymes

AbstractCardiac cells express more than one isoform of the Na, K-ATPase (NKA), the heteromeric enzyme that creates the Na+ and K+ gradients across the plasmalemma. Cardiac isozymes contain one catalytic α-subunit isoform (α1, α2, or α3) associated with an auxiliary β-subunit isoform (β1 or β2). Past studies using biochemical approaches have revealed minor kinetic differences between isozymes formed by different α-β isoform combinations; these results make it difficult to understand the physiological requirement for multiple isoforms. In intact cells, however, NKA enzymes operate in a more complex environment, which includes a substantial transmembrane potential. We evaluated the voltage dependence of human cardiac NKA isozymes expressed in Xenopus oocytes, and of native NKA isozymes in rat ventricular myocytes, using normal mammalian physiological concentrations of Na+o and K+o. We demonstrate that although α1 and α3 pumps are functional at all physiologically relevant voltages, α2β1 pumps and α2β2 pumps are inhibited by ∼75% and ∼95%, respectively, at resting membrane potentials, and only activate appreciably upon depolarization. Furthermore, phospholemman (FXYD1) inhibits pump function without significantly altering the pump’s voltage dependence. Our observations provide a simple explanation for the physiological relevance of the α2 subunit (∼20% of total α subunits in rat ventricle): they act as a reserve and are recruited into action for extra pumping during the long-lasting cardiac action potential, where most of the Na+ entry occurs. This strong voltage dependence of α2 pumps also helps explain how cardiotonic steroids, which block NKA pumps, can be a beneficial treatment for heart failure: by only inhibiting the α2 pumps, they selectively reduce NKA activity during the cardiac action potential, leading to an increase in systolic Ca2+, due to reduced extrusion through the Na/Ca exchanger, without affecting resting Na+ and Ca2+ concentrations

Role of color doppler imaging in early diagnosis and prediction of progression in glaucoma

This longitudinal and prospective study analyzes the ability of orbital blood flow measured by color Doppler imaging (CDI) to predict glaucoma progression in patients with glaucoma risk factors. Patients with normal perimetry but having glaucoma risk factors and patients in the initial phase of glaucoma were prospectively included in the study and divided, after a five-year follow-up, into two groups: “Progression” and “No Progression” based on the changes in the Moorfields regression analysis (MRA) classification of Heidelberg retina tomograph (HRT). An orbital CDI was performed in all patients and the parameters obtained were correlated with changes in HRT. A logistic discrimination function (LDF) was calculated for ophthalmic artery (OA) and central retinal artery (CRA) parameters. Receiver operating characteristics curves (ROC) were used to assess the usefulness of LDFs to predict glaucomatous progression. A total of 71 eyes were included. End-diastolic velocity, time-averaged velocity, and resistive index in the OA and CRA were significantly different ( ) between the Progression and No Progression groups. The area under the ROC curves calculated for both LDFs was of 0.695 (OA) and 0.624 (CRA). More studies are needed to evaluate the ability of CDI to perform early diagnosis and to predict progression in glaucoma in eyes