972 research outputs found

    The Role of Purinergic Signaling in the Pathophysiology of Perinatal Hypoxic-Ischemic Encephalopathy

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    Perinatal hypoxic-ischemic encephalopathy (HIE), known as birth asphyxia, remains a major contributor to poor neurodevelopmental outcomes including cerebral palsy and seizures. One striking feature of HIE injury is a delayed progression of neuronal degeneration that spreads over time from the most severely damaged areas outward into neighboring undamaged regions. There is increasing evidence that these lesions act as sites of origin for waves of spreading depression (SD), a wave of neuronal and glial depolarization, that progressively enlarge the brain lesions. While the pathophysiology of SD is still under debate, there is increasing evidence that purinergic receptors in conjunction with connexin and pannexin 1 channels are necessary for sustained propagation of the waves and neuroinflammation. This review intends to discuss the relative contribution of purinergic signaling and connexin and pannexin 1 channels to trigger and spread SD waves leading to the development of progressive brain lesions under conditions of perinatal HIE

    Functional recovery of tropical forests: The role of restoration methods and environmental conditions

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    Forest and landscape restoration strategies influence the recovery of plant functional traits, which in turn shape ecosystem processes. To understand how traits respond to restoration and environmental conditions, we assessed the functional recovery of three forest restoration types in Brazil's Atlantic Forest: natural regeneration, high-diversity restoration plantations (20–60 species), and unmanaged tree monocultures. Across 285 plots aged 1–76 years, we quantified seven leaf and stem traits for over 500 species. For each plot, we calculated community mean trait values and three functional diversity indices. The three restoration types showed contrasting successional patterns. Natural regeneration and restoration plantations shifted from acquisitive to conservative resource-use strategies with site age, while monocultures moved in the opposite direction. Restoration plantations exhibited the highest functional richness. Soil conditions (sand content and sum of bases) influenced trait composition and diversity, whereas climate and landscape context had smaller effects. In 20-year old sites, most traits in natural regeneration and restoration plantations approached 90 % of forest remnants values. In contrast, unmanaged monocultures recovered slowly, with only half of the traits reaching this threshold in 40-year old sites. Our findings show that restoration methods and site conditions jointly shape functional recovery. Natural regeneration tends to align with forest remnant traits, restoration plantations speed up early recovery but may diverge over time, and monocultures require active interventions to enhance outcomes. Recognizing these functional trajectories is key to improving biodiversity conservation and ecosystem resilience in tropical forest restoration

    Distribution of hepatitis B virus subgenotype F2a in São Paulo, Brazil

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    Abstract\ud \ud \ud \ud Background\ud HBV genotype F is primarily found in indigenous populations from South America and is classified in four subgenotypes (F1 to F4). Subgenotype F2a is the most common in Brazil among genotype F cases. The aim of this study was to characterize HBV genotype F2a circulating in 16 patients from São Paulo, Brazil. Samples were collected between 2006 and 2012 and sent to Hospital Israelita Albert Einstein. A fragment of 1306 bp partially comprising HBsAg and DNA polymerase coding regions was amplified and sequenced. Viral sequences were genotyped by phylogenetic analysis using reference sequences from GenBank (n=198), including 80 classified as subgenotype F2a. Bayesian Markov chain Monte Carlo simulation implemented in BEAST v.1.5.4 was applied to obtain the best possible estimates using the model of nucleotide substitutions GTR+G+I.\ud \ud \ud \ud Findings\ud It were identified three groups of sequences of subgenotype F2a: 1) 10 sequences from São Paulo state; 2) 3 sequences from Rio de Janeiro and one from São Paulo states; 3) 8 sequences from the West Amazon Basin.\ud \ud \ud \ud Conclusions\ud These results showing for the first time the distribution of F2a subgenotype in Brazil. The spreading and the dynamic of subgenotype F2a in Brazil requires the study of a higher number of samples from different regions as it is unfold in almost all Brazilian populations studied so far. We cannot infer with certainty the origin of these different groups due to the lack of available sequences. Nevertheless, our data suggest that the common origin of these groups probably occurred a long time ago.This work has been supported by CNPq and by Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP 2011/50562-0 and 2008/50461-6, HCFMUSP, FFM, Alves de Queiroz Family Fund for Research and IIRS-SBIBAE. These supported institutions provided the found to development the DNA amplification, sequencing and phylogenetic analysis

    De que contexto se fala? Análise de livros didáticos de Química para o ensino médio

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    Esta comunicação apresenta a análise de livros didáticos de Química para o ensino médio, indicados no PNLD 2012 (Brasil, 2011), em relação a contextualização dos conteúdos químicos, como resultado de atividade desenvolvida com bolsistas do Programa Institucional de Bolsa de Iniciação a Docência do curso de Licenciatura em Química da Universidade Federal da Bahia (PIBID/UFBA), contando com a participação dos estudantes matriculados na disciplina Ensino de Química no Contexto, no semestre 2011.2. Foram consideradas três categorias de análise, baseadas em Silva (2007) e os resultados apontaram que dos livros analisados, três apresentam a contextualização como exemplificação e/ou informação do cotidiano, um apresenta contextualização relacionada ao movimento CTS e um outro aproxima-se também desse tipo de contextualização, embora tenha como foco a construção do conhecimento

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Distribution of hepatitis B virus subgenotype F2a in São Paulo, Brazil

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    Abstract\ud \ud \ud \ud Background\ud HBV genotype F is primarily found in indigenous populations from South America and is classified in four subgenotypes (F1 to F4). Subgenotype F2a is the most common in Brazil among genotype F cases. The aim of this study was to characterize HBV genotype F2a circulating in 16 patients from São Paulo, Brazil. Samples were collected between 2006 and 2012 and sent to Hospital Israelita Albert Einstein. A fragment of 1306 bp partially comprising HBsAg and DNA polymerase coding regions was amplified and sequenced. Viral sequences were genotyped by phylogenetic analysis using reference sequences from GenBank (n=198), including 80 classified as subgenotype F2a. Bayesian Markov chain Monte Carlo simulation implemented in BEAST v.1.5.4 was applied to obtain the best possible estimates using the model of nucleotide substitutions GTR+G+I.\ud \ud \ud \ud Findings\ud It were identified three groups of sequences of subgenotype F2a: 1) 10 sequences from São Paulo state; 2) 3 sequences from Rio de Janeiro and one from São Paulo states; 3) 8 sequences from the West Amazon Basin.\ud \ud \ud \ud Conclusions\ud These results showing for the first time the distribution of F2a subgenotype in Brazil. The spreading and the dynamic of subgenotype F2a in Brazil requires the study of a higher number of samples from different regions as it is unfold in almost all Brazilian populations studied so far. We cannot infer with certainty the origin of these different groups due to the lack of available sequences. Nevertheless, our data suggest that the common origin of these groups probably occurred a long time ago.This work has been supported by CNPq and by Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP 2011/50562-0 and 2008/50461-6, HCFMUSP, FFM, Alves de Queiroz Family Fund for Research and IIRS-SBIBAE. These supported institutions provided the found to development the DNA amplification, sequencing and phylogenetic analysis

    Learning curve for in-hospital mortality of transcatheter aortic valve replacement: insights from the brazilian national registry

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    Background: Robust data on the learning curve (LC) of transcatheter aortic valve replacement (TAVR) are lacking in developing countries. Objective: To assess TAVR’s LC in Brazil over time. Methods: We analyzed data from the Brazilian TAVR registry from 2008 to 2023. Patients from each center were numbered chronologically in case sequence numbers (CSNs). LC was performed using restricted cubic splines adjusted for EuroSCORE-II and the use of new-generation prostheses. Also, in-hospital outcomes were compared between groups defined according to the level of experience based on the CSN: 1st to 40th (initial-experience), 41st to 80th (early-experience), 81st to 120th (intermediate-experience), and over 121st (high-experience). Additional analysis was performed grouping hospitals according to the number of cases treated before 2014 (>40 and ≤40 procedures). The level of significance adopted was <0.05. Results: A total of 3,194 patients from 25 centers were included. Mean age and EuroSCORE II were 80.7±8.1 years and 7±7.1, respectively. LC analysis demonstrated a drop in adjusted in-hospital mortality after treating 40 patients. A leveling off of the curve was observed after case #118. In-hospital mortality across the groups was 8.6%, 7.7%, 5.9%, and 3.7% for initial-, early-, intermediate-, and high-experience, respectively (p<0.001). High experience independently predicted lower mortality (OR 0.57, p=0.013 vs. initial experience). Low-volume centers before 2014 showed no significant decrease in the likelihood of death with gained experience, whereas high-volume centers had a continuous improvement after case #10. Conclusion: A TAVR LC phenomenon was observed for in-hospital mortality in Brazil. This effect was more pronounced in centers that treated their first 40 cases before 2014 than those that reached this milestone after 2014

    Use and misuse of trait imputation in ecology: the problem of using out‐of‐context imputed values

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    Despite the progress in the measurement and accessibility of plant trait information, acquiring sufficiently complete data from enough species to answer broad‐scale questions in plant functional ecology and biogeography remains challenging. A common way to overcome this challenge is by imputation, or ‘gap‐filling' of trait values. This has proven appropriate when focusing on the overall patterns emerging from the database being imputed. However, some applications force the imputation procedure out of its original scope, using imputed values independently from the imputation context, and specific trait values for a given species are used as input for computing new variables. We tested the performance of three widely used imputation methods (Bayesian hierarchical probabilistic matrix factorization, multiple imputation by chained equations with predictive mean matching, and Rphylopars) on a database of tropical tree and shrub traits. By applying a leave‐one‐out procedure, we assessed the accuracy and precision of the imputed values and found that out‐of‐context use of imputed values may bias the estimation of different variables. We also found that low redundancy (i.e. low predictability of a new value on the basis of existing values) in the dataset, not uncommon for empirical datasets, is likely the main cause of low accuracy and precision in the imputed values. We therefore suggest the use of a leave‐one‐out procedure to test the quality of the imputed values before any out‐of‐context application of the imputed values, and make practical recommendations to avoid the misuse of imputation procedures. Furthermore, we recommend not publishing gap‐filled datasets, publishing instead only the empirical data, together with the imputation method applied and the corresponding script to reproduce the imputation. This will help avoid the spread of imputed data, whose accuracy, precision, and source are difficult to assess and track, into the public domain
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