Prevalência de Doença Carotídea na Patologia Cérebro-Vascular Isquémica. O Papel do Eco-Doppler

BACKGROUND: Atherosclerotic carotid disease represents approximately 20% of the causes of ischemic stroke. Effective treatment options, such as endovascular or surgical revascularization procedures, are available. Doppler Ultrasound (DUS) is a non-invasive, inexpensive, routine exam used to evaluate the presence of internal carotid artery (ICA) stenosis. We retrospectively analysed the prevalence of severe atherosclerotic carotid disease in a population of patients with acute ischemic stroke/transitory ischemic attacks (TIAs), and the role of DUS in the detection of ICA stenosis and treatment decisions in these patients. METHODS: A total of 318 patients with ischemic stroke or TIAs was admitted to our stroke unit, and 260 patients were studied by DUS. ICA stenosis was evaluated by DUS according to peak systolic velocity. All DUS exams were performed by the same operator. ICA stenosis was further assessed in 43 patients by digital subtraction angiography (DSA) using NASCET criteria. RESULTS: Of the total 318 patients, 260 (82%) had DUS evaluation. Of the total 520 ICAs studied by DUS, degrees of ICA stenosis were: 0-29% n= 438 (84%); 30-49% n= 8 (2%); 50-69% n= 27 (5%); 70-89% n= 15 (3%); 90-99% n= 20 (4%); oclusão n= 14 (2%). Of the total 260 patients studied, 43 (16.5%) underwent DSA. Sensibility and specificity of DUS in the diagnosis of carotid stenosis over 70% were, respectively, 91% e 84%. Of the total 31 patients with significant carotid stenosis (70-99%), 23 (74%) underwent subsequent carotid revascularization procedures. DISCUSSION: DUS is an important screening test in our stroke unit, justifying its use as a routine exam for all patients with ischemic stroke/TIAs. Moreover, our results show the relevance of severe carotid disease in a population with acute ischemic stroke/TIAs (16.5%), with a total of 9% of patients being submitted to carotid revascularization procedures

The term structure of interest rates in a heterogeneous monetary union

Es difícil cuadrar la reacción asimétrica de las curvas de tipos en el área del euro tras el anuncio del programa de compras de emergencia frente a la pandemia (PEPP, por sus siglas en inglés) del Banco Central Europeo (BCE) con la interpretación ortodoxa de los efectos de las compras de bonos por parte de los bancos centrales, que enfatiza un mecanismo de «extracción de riesgo de duración». Motivados por esta observación, construimos un modelo de curvas de tipos soberanas en una unión monetaria de dos países, uno de los cuales emite bonos sin riesgo de impago, mientras que los bonos del otro pueden sufrir un impago. Obtenemos una solución analítica afín para la estructura temporal de los tipos soberanos, y descomponemos los rendimientos en componentes relacionados con la prima de plazo y con el riesgo de crédito. A continuación, extendemos el modelo básico para endogenizar la probabilidad de impago por parte del país periférico. Debido a la posibilidad de no poder refinanciar la deuda durante una crisis de liquidez, la probabilidad de impago soberano es una función creciente de la oferta de bonos soberanos neta de las tenencias del banco central. Calibramos el modelo para Alemania e Italia, y mostramos que el modelo replica bien la reacción de las curvas de tipos de estos países al anuncio del PEPP. Un mecanismo que llamamos «extracción de riesgo de impago» explica la mayor parte del impacto sobre los tipos italianos. La flexibilidad del diseño del PEPP aumentó de manera material el impacto de las compras.The highly asymmetric reaction of euro area yield curves to the announcement of the ECB’s pandemic emergency purchase programme (PEPP) is hard to reconcile with the standard “duration risk extraction” view of the transmission of central banks’ asset purchase policies. This observation motivates us to build a no-arbitrage model of the term structure of sovereign interest rates in a two-country monetary union, in which one country issues default-free bonds and the other issues defaultable bonds. We derive an affine term structure solution, and we decompose yields into term premium and credit risk components. In an extension, we endogenise the peripheral default probability, showing that the possibility of rollover crises makes it an increasing function of bond supply net of central bank holdings. We calibrate the model to Germany and Italy, showing that it matches well the reaction of these countries’ yield curves to the PEPP announcement. A channel we call “default risk extraction” accounts for most of the impact on Italian yields. The programme’s flexible design substantially enhanced this impact

Molecular dynamics simulations of the conformational changes of the glutamate receptor ligand-binding core in the presence of glutamate and kainate.

ABSTRACT Excitatory synaptic transmission is mediated by ionotropic glutamate receptors (iGluR

Molecular dynamics simulations of the conformational changes of the glutamate receptor ligand-binding core in the presence of glutamate and kainate.

ABSTRACT Excitatory synaptic transmission is mediated by ionotropic glutamate receptors (iGluR

Gold recycling at laboratory scale: from nanowaste to nanospheres

The market for products based on nanotechnology, and with it the use of nanomaterials and the generation of nanowaste, increases day by day. Among the vast variety of nanomaterials available, gold nanoparticles (AuNPs) are among the most studied and applied in commercial products. This current situation requires both the development of recovery methods to reduce the amount of nanowaste produced, and new synthetic methods that allow the reuse of recovered gold for new nanomaterial production, keeping in mind both economical and ecological considerations. In this work, a methodology to recover gold from aqueous laboratory nanowaste and transform it into an aqueous HAuCl4 solution was developed, using extremely simple procedures and readily available chemical reagents (NaCl, HCl, H2O2) and allowing the recovery of more than 99 % of the original gold. The experiments were performed by using both simulated and real laboratory nanowastes, and practically the same results were obtained. Moreover, the subsequent use of the obtained aqueous HAuCl4 solution from the recovered gold to produce spherical AuNPs through a seed-mediated approach was demonstrated. Thus, this work presents for the first time a complete recycling cycle from nanowaste to the reagent and back to the nanomaterial.Fil: Oestreicher, Víctor Santiago Jesús. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; ArgentinaFil: García, Carolina S.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martin. Instituto de Nanosistemas; ArgentinaFil: Angelome, Paula Cecilia. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; Argentin

Burnt areas semantic segmentation from Sentinel data using the U-Net network trained with semi-automated annotations

The Pantanal biome is one of the most important wetlands on the planet, harboring a rich biodiversity whilst being critical in maintaining hydrological cycles and climate regulation. However, the occurrence of fires in the biome has represented a significant threat to this unique ecosystem and its multiple functions. Understanding the extent, intensity and environmental impacts caused by fires in the Pantanal, is of unique importance for the preservation of the biome's biodiversity. Remote sensing techniques have played an important role in detecting and mapping burnt areas, especially SAR (Synthetic Aperture Radar) orbital systems, that are able to collect data in regions with frequent cloud cover or during extreme fire events. In this context, the objective of this study was to evaluate the potential of the U-Net semantic segmentation network applied to SAR data in the detection of burnt areas in the Brazilian Pantanal. For this, a semi-automatic annotated dataset was generated and considered as ground truth to evaluate the result obtained by the network. Two input datasets were evaluated in the detection of burnt areas, one containing optical and SAR data whereas the other containing only SAR data. The predictions of the two datasets were consistent with the semi-automatically generated annotation, showing similar spatial distribution but presenting a greater number of burnt areas. The model using both optical and SAR data achieved IoU (Intersection of Union) of 0.69 whereas the SAR only model had 0.60. Considering the amount of available data and the complexity of burnt area detection, the predictions achieved were adequate

Kainate-Triggered Currents in Xenopus Oocytes Injected with Chick Retinal Membrane Fragments: Effect of Guanine Nucleotides

PURPOSE. To electrophysiologically characterize ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/kainate receptors in chick retinal membrane fragments, incorporated into Xenopus oocytes by direct microinjection. METHODS. A 6-day retinal membrane suspension was injected into Xenopus oocytes by use of an electronic nanoliter injector. Fifteen to 40 hours after injection, the oocytes were assayed for kainate-elicited inward currents, under voltage-clamp conditions (membrane potential held at Ϫ70 mV). The structural incorporation of the retinal membrane fragments into the oocyte membrane was verified by specific immunofluorescent staining. RESULTS. Chick retinal membrane fragments were efficiently grafted onto Xenopus oocytes after microinjection, with 22.9% Ϯ 7.6% of the oocyte membrane being stained with anti-chick retina antibody. Part of the retinal material was seen as patches of relatively uniform size (292.1 Ϯ 72.3 m 2 ). Bath-applied kainate induced dose-dependent (EC 50 : 64 Ϯ 7 M), nondesensitizing inward currents (15-90 nA) in the chimeric Xenopus oocytes. Sham-injected oocytes did not respond to kainate. Kainate-driven currents were blocked by 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 1-(4-aminopropyl)-4-methyl-7,8-methylenedioxy-5H-2,3-benzodiazepine hydrochloride (GYKI 52466), but not by ␥-D-glutamylaminomethyl sulfonic acid (GAMS) or aminophosphonoheptanoate (AP7), suggesting the involvement of AMPA receptors in the observed responses. Guanine nucleotides (GNs) also blocked kainate currents in a concentration-dependent manner. CONCLUSIONS. An alternative oocyte microinjection technique to analyze the electrophysiological properties of glutamate receptors in chick retinal membranes is described. The results show the functional activity of putative AMPA-preferring receptors from chick retina and confirm, in the chick retinal model, the antagonistic behavior of guanine nucleotides toward glutamate receptors and their potential role as neuropro- These results add to the accumulated evidence on the antagonistic behavior of guanine nucleotides (GNs) at ionotropic glutamate receptors, in very diverse experimental setups, including agonist displacement, electrophysiological recording and neuroprotection paradigms. 21,22 MATERIALS AND METHODS Chick Retinal Membrane Preparation All experiments with animals (chicks, Xenopus, and rabbits) followed our institutional guidelines for care and handling of laboratory animals, in full agreement with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. Six-day-old white leghorn chicks were used as the source of retinal membrane fragments. Lysed membranes, prepared as described, 7 were resuspended in 10 mM HEPES (pH 7.4), containing 140 mM KCl and 20 mM NaCl, at a protein concentration of 2 mg/mL, stored in liquid nitrogen, and thawed and sonicated for 10 seconds in an ice water bath just before injection. A control solution without membranes was similarly processed and used for sham-injected control chicks. Oocyte Preparation and Injection Mature female Xenopus laevis were obtained from the Centre d'Elevage des Xénopes, CRBM (Montpellier, France), and kept in chlorine-free fresh water, at 22°C. Discrete ovary portions were removed from anesthetized frogs 23 and stage-V/VI oocytes 24 were individually dissected and kept, at 15°C to 17°C, in sterile modified Barth's solution (10 mM HEPES [pH 7.4], 88 mM NaCl, 1 mM KCl, 0.33 mM Ca(NO 3 ) 2 , 0.41 mM CaCl 2 , 0.82 mM MgSO 4 , and 2.4 mM NaHCO 3 ) supplemented with penicillin (100 IU/mL) and streptomycin (0.1 mg/mL). Oocytes were further treated with collagenase (clostridiopeptidase A: EC3.4.24.3; type IA, 0.5 mg/mL; Sigma-Aldrich, St. Louis, MO), for 50 minutes at room temperature, to remove enveloping cells. 25 From th

Epidemiological characterization of ischemic heart disease at different altitudes: a nationwide population-based analysis from 2011 to 2021 in Ecuador

Background Cardiovascular diseases, including ischemic heart disease, are the leading cause of prema- ture death and disability worldwide. While traditional risk factors such as smoking, obesity, and diabetes have been thoroughly investigated, non-traditional risk factors like high-alti- tude exposure remain underexplored. This study aims to examine the incidence and mortal- ity rates of ischemic heart disease over the past decade in Ecuador, a country with a diverse altitude profile spanning from 0 to 4,300 meters. Methods We conducted a geographic distribution analysis of ischemic heart disease in Ecuador, uti- lizing hospital discharge and mortality data from the National Institute of Census and Statis- tics for the years 2011–2021. Altitude exposure was categorized according to two distinct classifications: the traditional division into low ( 2,500 m) altitudes, as well as the classification proposed by the International Society of Mountain Medicine, which delineates low (2500 m. Men had more pronounced rates across altitudes, exhibiting 138.7% and 150.0% higher incidence at low and high altitudes respectively, and mortality rates increased by 48.3% at low altitudes and 23.2% at high altitudes relative to women. Conclusion Ecuador bears a significant burden of ischemic heart disease (IHD), with men being more affected than women in terms of incidence. However, women have a higher percentage of mortality post-hospital admission. Regarding elevation, our analysis, using two different alti- tude cutoff points, reveals higher mortality rates in low-altitude regions compared to high- altitude areas, suggesting a potential protective effect of high elevation on IHD risk. Never- theless, a definitive dose-response relationship between high altitude and reduced IHD risk could not be conclusively established