Fibrillar organization in tendons: a pattern revealed by percolation characteristics of the respective geometric network

Since the tendon is composed by collagen fibrils of various sizes connected between them through molecular cross-links, it sounds logical to model it via a heterogeneous network of fibrils. Using cross sectional images, that network is operatively inferred from the respective Gabriel graph of the fibril mass centers. We focus on network percolation characteristics under an ordered activation of fibrils (progressive recruitment going from the smallest to the largest fibril). Analyses of percolation were carried out on a repository of images of digital flexor tendons obtained from samples of lizards and frogs. Observed percolation thresholds were compared against values derived from hypothetical scenarios of random activation of nodes. Strikingly, we found a significant delay for the occurrence of percolation in actual data. We interpret this finding as the consequence of some non-random packing of fibrillar units into a size-constrained geometric pattern. We erect an ideal geometric model of balanced interspersion of polymorphic units that accounts for the delayed percolating instance. We also address the circumstance of being percolation curves mirrored by the empirical curves of stress-strain obtained from the same studied tendons. By virtue of this isomorphism, we hypothesize that the inflection points of both curves are different quantitative manifestations of a common transitional process during mechanical load transference.Fil: Dos Santos, Daniel Andrés. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Ponssa, María Laura. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tulli, María José. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto de Biodiversidad Neotropical; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Fundación Miguel Lillo. Dirección de Zoología. Instituto de Herpetología; Argentin

Chemoreception and neuroplasticity in respiratory circuits

The respiratory central pattern generator must respond to chemosensory cues to maintain oxygen (O2) and carbon dioxide (CO2) homeostasis in the blood and tissues. To do this, sensorial cells located in the periphery and central nervous system monitor the arterial partial pressure of O2 and CO2 and initiate respiratory and autonomic reflex adjustments in conditions of hypoxia and hypercapnia. In conditions of chronic intermittent hypoxia (CIH), repeated peripheral chemoreceptor input mediated by the nucleus of the solitary tract induces plastic changes in respiratory circuits that alter baseline respiratory and sympathetic motor outputs and result in chemoreflex sensitization, active expiration, and arterial hypertension. Herein, we explored the hypothesis that the CIH-induced neuroplasticity primarily consists of increased excitability of pre-inspiratory/inspiratory neurons in the pre-Bötzinger complex. To evaluate this hypothesis and elucidate neural mechanisms for the emergence of active expiration and sympathetic overactivity in CIH-treated animals, we extended a previously developed computational model of the brainstem respiratory-sympathetic network to reproduce experimental data on peripheral and central chemoreflexes post-CIH. The model incorporated neuronal connections between the 2nd-order NTS neurons and peripheral chemoreceptors afferents, the respiratory pattern generator, and sympathetic neurons in the rostral ventrolateral medulla in order to capture key features of sympathetic and respiratory responses to peripheral chemoreflex stimulation. Our model identifies the potential neuronal groups recruited during peripheral chemoreflex stimulation that may be required for the development of inspiratory, expiratory and sympathetic reflex responses. Moreover, our model predicts that pre-inspiratory neurons in the pre-Bötzinger complex experience plasticity of channel expression due to excessive excitation during peripheral chemoreflex. Simulations also show that, due to positive interactions between pre-inspiratory neurons in the pre-Bötzinger complex and expiratory neurons in the retrotrapezoid nucleus, increased excitability of the former may lead to the emergence of the active expiratory pattern at normal CO2 levels found after CIH exposure. We conclude that neuronal type specific neuroplasticity in the pre-Bötzinger complex induced by repetitive episodes of peripheral chemoreceptor activation by hypoxia may contribute to the development of sympathetic over-activity and hypertension

Uma metodologia para criação de cérebros médios e mensuração da atrofia relativa do córtex

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.Devido à grande variabilidade anatômica relativa ao cérebro do ser humano, o seu estudo implica uma área incerta da ciência, e esforços direcionados ao objetivo de gerar um mapeamento dessa complexa estrutura obtêm constantes sucessos, mas também fracassos. Atualmente, com a crescente capacidade computacional e com a disponibilidade de metodologias para alinhamento de imagens, novos passos direcionados ao esforço de mapear o cérebro humano estão sendo dados. A existência de um "cérebro médio", que seja estatisticamente representativo em relação às características de uma dada população, pode vir a auxiliar o acompanhamento da evolução de doenças degenerativas cerebrais, ao fornecer uma base sólida para identificação de anomalias, assim como para servir de base para a tomada de decisão clínica. Este trabalho apresenta o resultado de dois anos de pesquisa e desenvolvimento junto ao projeto Cyclops, no intuito da elaboração de uma metodologia de registro volumétrico de imagens médicas e conseqüente geração de mapas médios do cérebro humano. Como fator motivador deste trabalho desenvolveu-se uma metodologia para a avaliação do grau de atrofia global e local do córtex cerebral, com o intuito de auxiliar os médicos neurorradiologistas no processo de diagnóstico precoce da doença de Alzheimer, assim como no acompanhamento e predição da evolução estatisticamente representativa do estado de MCI- Mild Cognitive Inparment para a doença de Alzheimer. Ao final da pesquisa obteve-se: a) descrição metodológica de geração de cérebros médios. b) uma ferramenta para registro de imagens mono-modais/multi-subject; c) ferramenta para geração de cérebros médios; d) ferramenta de geração de mapas de cores para salientar regiões atrofiadas do córtex; e) todas as funcionalidades discutidas neste trabalho sob a forma de um framework extensível

Ensemble and constrained clustering with applications

Diese Arbeit stellt neue Entwicklungen in Ensemble und Constrained Clustering vor und enthält die folgenden wesentlichen Beiträge: 1) Eine Vereinigung von Constrained und Ensemble Clustering in einem einheitlichen Framework. 2) Eine neue Methode zur Messung und Visualisierung der Variabilität von Ensembles. 3) Ein neues, Random Walker basiertes Verfahren für Ensemble Clustering. 4) Anwendung von Ensemble Clustering für Bildsegmentierung. 5) Eine neue Consensus-Funktion für das Ensemble Clustering Problem. Schließlich 6) Anwendung von Constrained Clustering zur Segmentierung von Nervenfasern in der Diffusions-Tensor-Bildgebung. In umfangreichen Experimenten wurden diese Verfahren getestet und ihre Überlegenheit gegenüber existierenden Methoden aus der Literatur demonstriert

Geographical Information System Applied to a Biological System: Pelvic Girdle Ontogeny as a Morphoscape

Geographic Information System (GIS) is a system that captures, stores, manipulates, analyzes, manages, and presents spatial or geographical data. As this technological environment has been created to deal with space problems, it is perfectly adaptable to solve these type of issues in the context of vertebrate comparative morphology. The pectoral and pelvic girdles are key structures that relate the axial skeleton with the limbs in tetrapods. Owed to their importance in locomotion, the morphology, development, and morphogenesis of these structures have been widely studied. The complexity of the structures and tissues implied in the development of the girdles make quantitative approaches extremely difficult. The use of GIS technology provides a visual interpretation of the histological data, a general quantitative assessment of the processes taking place during the ontogeny of any structure, and would allow collecting information about the changes in the surface occupied by the different tissues across the ontogenetic processes of any vertebrate taxa. GIS technology applied to map morphological structures would be a main contribution to the construction of the vertebrate ontologies, as it would facilitate the identification and location of the structures. GIS technology would allow also us to construct a shared database of histological quantitative changes across the ontogeny in any vertebrate. The main objective of this study is to use GIS technology for spatial analysis of histological samples such as these of the pelvic girdle using histological cuts of anurans and chicken, allowing thus to construct a morphoscape, analogous to a landscape. This is the first attempt to apply GIS tools to ontogenetic series to infer biological properties of the spatial analysis in the context of comparative biology. More frequent use of this technology would contribute to obtaining more profitable and biologically informative results.Fil: Abdala, Virginia Sara Luz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Cristobal, Luciana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Soliz, Monica Carina. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dos Santos, Daniel Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentin

Fast two-step segmentation of natural color scenes using hierarchical region-growing and a Color-Gradient Network

Abstract We present evaluation results with focus on combined image and efficiency performance of the Gradient Network Method to segment color images, especially images showing outdoor scenes. A brief review of the techniques, Gradient Network Method and Color Structure Code, is also presented. Different region-growing segmentation results are compared against ground truth images using segmentation evaluation indices Rand and Bipartite Graph Matching. These results are also confronted with other well established segmentation methods (EDISON and JSEG). Our preliminary results show reasonable performance in comparison to several state-of-art segmentation techniques, while also showing very promising results comparatively in the terms of efficiency, indicating the applicability of our solution to real time problems.</jats:p

Endophytic Bacteria Improve Seedling Growth of Sunflower Under Water Stress, Produce Salicylic Acid, and Inhibit Growth of Pathogenic Fungi

Endophytic bacterial strains SF2 (99.9% homology with Achromobacter xylosoxidans), and SF3 and SF4 (99.9% homology with Bacillus pumilus) isolated from sunflower grown under irrigation or drought were selected on the basis of plant growth-promoting bacteria (PGPB) characteristics. Aims of the study were to examine effects of inoculation with SF2, SF3, and SF4 on sunflower cultivated under water stress, to evaluate salicylic acid (SA) production by these strains in control medium or at Ψa = -2.03 MPa, and to analyze effects of exogenously applied SA, jasmonic acid (JA), bacterial pellets, and bacterial supernatants on growth of pathogenic fungi Alternaria sp., Sclerotinia sp., and Verticillum sp. Growth response to bacterial inoculation was studied in two inbred lines (water stress-sensitive B59 and water stress-tolerant B71) and commercial hybrid Paraiso 24. Under both water stress and normal conditions, plant growth following inoculation was more strongly enhanced for Paraiso 24 and B71 than for B59. All three strains produced SA in control medium; levels for SF3 and SF4 were higher than for SF2. SA production was dramatically higher at Ψa = -2.03 MPa. Exogenously applied SA or JA caused a significant reduction of growth for Sclerotinia and a lesser reduction for Alternaria and Verticillum. Fungal growth was more strongly inhibited by bacterial pellets than by bacterial supernatants. Our findings indicate that these endophytic bacteria enhance growth of sunflower seedlings under water stress, produce SA, and inhibit growth of pathogenic fungi. These characteristics are useful for formulation of inoculants to improve growth and yield of sunflower crops. © 2010 Springer Science+Business Media, LLC.Fil: Forchetti, Gabriela Noemi. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Cátedra de Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Masciarelli, Oscar Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Cátedra de Fisiología Vegetal; ArgentinaFil: Izaguirre, Maria J.. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Cátedra de Fisiología Vegetal; ArgentinaFil: Alemano, Sergio Gabriel. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Cátedra de Fisiología Vegetal; ArgentinaFil: Alvarez, Daniel. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Manfredi. Departamento de Producción Vegetal; ArgentinaFil: Abdala, Guillermina Irene. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Cátedra de Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Infecção por Vírus Monkeypox: Avaliação do Doador e do Candidato ao Transplante de Órgãos Sólidos

Contextualização: Desde maio de 2022, casos de monkeypox (varíola dos macacos ou mpox) foram relatados em vários países, com evidências de transmissão comunitária. No cenário atual, temos transmissão identificada em diferentes continentes, relacionada com disseminação local do vírus por contato íntimo inter-humano. Objetivo: O objetivo desse artigo é informar a comunidade transplantadora sobre as eventuais implicações da doença para a população de receptores de transplantes e seus doadores. Método: Nesse artigo apresenta-se as orientações para adequar a avaliação de doadores e de candidatos a transplantes de órgãos, tendo em vista os riscos potenciais decorrentes da emergência de mpox em nosso meio. É importante considerar que este documento reflete a opinião de especialistas diante das escassas evidências atualmente disponíveis. Resultados e Conclusões: As recomendações de manejo e avaliação do doador baseiam-se no risco potencial da transmissão do vírux MPXV. Estima-se que o risco de transmissão pelo transplante seja baixo, levando-se em conta a incerteza sobre a duração da viremia em pacientes com mpox e a presença de vírusviável em células e tecidos. Recomenda-se, no entanto, que os médicos responsáveis pelo paciente estejam alerta para as evidências de infecção e que acionem ou notifiquem as instituições caso haja indícios de transmissão pelo transplante

Infecção por vírus monkeypox: avaliação do doador e do candidato ao transplante de órgãos sólidos

Contextualization: Since May 2022, cases of monkeypox (mpox) have been reported in several countries, with evidence of community transmission. In the current scenario, transmission has been identified in diferent continents, related to the local spread of the virus by intimate inter-human contact. Objective: The purpose of this article is to inform the transplant community about the possible implications of the disease for the population of transplant recipients and their donors. Method: This article presents guidelines for adapting the evaluation of donors and candidates for organ transplants, bearing in mind the potential risks resulting from the emergence of mpox in our midst. It is important to consider that this document reflects the opinion of specialists given the scarce evidence currently available. Results and Conclusions: Donor assessment and management recommendations are based on the potential risk of monkeypox virus (MPXV) transmission. The risk of transmission by transplantation is estimated to be low, taking into account the uncertainty about the duration of viremia in patients with mpox and the presence of viable virus in cells and tissues. It is recommended, however, that the physicians responsible for the patient are alert to evidence of infection and that they activate or notify the institutions in case there are indications of transmission through the transplant.Contextualização: Desde maio de 2022, casos de monkeypox (varíola dos macacos ou mpox) foram relatados em vários países, com evidências de transmissão comunitária. No cenário atual, temos transmissão identi cada em diferentes continentes, relacionada com disseminação local do vírus por contato íntimo inter-humano. Objetivo: O objetivo desse artigo é informar a comunidade transplantadora sobre as eventuais implicações da doença para a população de receptores de transplantes e seus doadores. Método: Nesse artigo apresenta-se as orientações para adequar a avaliação de doadores e de candidatos a transplantes de órgãos, tendo em vista os riscos potenciais decorrentes da emergência de mpox em nosso meio. É importante considerar que este documento re ete a opinião de especialistas diante das escassas evidências atualmente disponíveis. Resultados e Conclusões: As recomendações de manejo e avaliação do doador baseiam-se no risco potencial da transmissão do vírux MPXV. Estima-se que o risco de transmissão pelo transplante seja baixo, levando-se em conta a incerteza sobre a duração da viremia em pacientes com mpox e a presença de vírus viável em células e tecidos. Recomenda-se, no entanto, que os médicos responsáveis pelo paciente estejam alerta para as evidências de infecção e que acionem ou notifiquem as instituições caso haja indícios de transmissão pelo transplante