Modular structure in C. elegans neural network and its response to external localized stimuli

Synchronization plays a key role in information processing in neuronal networks. Response of specific groups of neurons are triggered by external stimuli, such as visual, tactile or olfactory inputs. Neurons, however, can be divided into several categories, such as by physical location, functional role or topological clustering properties. Here we study the response of the electric junction C. elegans network to external stimuli using the partially forced Kuramoto model and applying the force to specific groups of neurons. Stimuli were applied to topological modules, obtained by the ModuLand procedure, to a ganglion, specified by its anatomical localization, and to the functional group composed of all sensory neurons. We found that topological modules do not contain purely anatomical groups or functional classes, corroborating previous results, and that stimulating different classes of neurons lead to very different responses, measured in terms of synchronization and phase velocity correlations. In all cases, however, the modular structure hindered full synchronization, protecting the system from seizures. More importantly, the responses to stimuli applied to topological and functional modules showed pronounced patterns of correlation or anti-correlation with other modules that were not observed when the stimulus was applied to ganglia.Comment: 23 pages, 6 figure

Binary Dynamics On Star Networks Under External Perturbations.

We study a binary dynamical process that is a representation of the voter model with two candidates and opinion makers. The voters are represented by nodes of a network of social contacts with internal states labeled 0 or 1 and nodes that are connected can influence each other. The network is also perturbed by opinion makers, a set of external nodes whose states are frozen in 0 or 1 and that can influence all nodes of the network. The quantity of interest is the probability of finding m nodes in state 1 at time t. Here we study this process on star networks, which are simple representations of hubs found in complex systems, and compare the results with those obtained for networks that are fully connected. In both cases a transition from disordered to ordered equilibrium states is observed as the number of external nodes becomes small. For fully connected networks the probability distribution becomes uniform at the critical point. For star networks, on the other hand, we show that the equilibrium distribution splits in two peaks, reflecting the two possible states of the central node. We obtain approximate analytical solutions for the equilibrium distribution that clarify the role of the central node in the process. We show that the network topology also affects the time scale of oscillations in single realizations of the dynamics, which are much faster for the star network. Finally, extending the analysis to two stars we compare our results with simulations in simple scale-free networks.9204281

Mesenchymal Stem Cell Therapy Modulates the Inflammatory Response in Experimental Traumatic Brain Injury

Therapy with mesenchymal stem cells (MSCs) has showed to be promising due to its immunomodulatory function. Traumatic brain injury (TBI) triggers immune response and release of inflammatory mediators, mainly cytokines, by glial cells creating a hostile microenvironment for endogenous neural stem cells (NSCs). We investigated the effects of factors secreted by MSCs on NSC in vitro and analyzed cytokines expression in vitro in a TBI model. Our in vitro results show that MSC-secreted factors increase NSC proliferation and induce higher expression of GFAP, indicating a tendency toward differentiation into astrocytes. In vivo experiments showed that MSC injection at an acute model of brain injury diminishes a broad profile of cytokines in the tissue, suggesting that MSC-secreted factors may modulate the inflammation at the injury site, which may be of interest to the development of a favorable microenvironment for endogenous NSC and consequently to repair the injured tissue

Brazilian cross-cultural adaptation and validation of the List of Threatening Events Questionnaire (LTE-Q)

Objective: To perform a construct validation of the List of Threatening Events Questionnaire (LTE-Q), as well as convergence validation by identifying its association with drug use in a sample of the Brazilian population. Methods: This is a secondary analysis of the Second Brazilian National Alcohol and Drugs Survey (II BNADS), which used a cross-cultural adaptation of the LTE-Q in a probabilistic sample of 4,607 participants aged 14 years and older. Latent class analysis was used to validate the latent trait adversity (which considered the number of events from the list of 12 item in the LTE experienced by the respondent in the previous year) and logistic regression was performed to find its association with binge drinking and cocaine use. Results: The confirmatory factor analysis returned a chi-square of 108.341, weighted root mean square residual (WRMR) of 1.240, confirmatory fit indices (CFI) of 0.970, Tucker-Lewis index (TLI) of 0.962, and root mean square error approximation (RMSEA) score of 1.000. LTE-Q convergence validation showed that the adversity latent trait increased the chances of binge drinking by 1.31 time and doubled the chances of previous year cocaine use (adjusted by sociodemographic variables). Conclusion: The use of the LTE-Q in Brazil should be encouraged in different research fields, including large epidemiological surveys, as it is also appropriate when time and budget are limited. The LTE-Q can be a useful tool in the development of targeted and more efficient prevention strategies.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Univ Fed Sao Paulo UNIFESP, Inst Nacl Pesquisa Alcool & Outras Drogas INCT IN, Sao Paulo, SP, BrazilUniv Fed Sao Paulo UNIFESP, Dept Psiquiatria, Sao Paulo, SP, BrazilUniv Municipal Sao Caetano USCS, Escola Saude, Sao Caetano do Sul, SP, BrazilPacific Inst Res & Evaluat, Oakland, CA USAUniv Fed Sao Paulo UNIFESP, Inst Nacl Pesquisa Alcool & Outras Drogas INCT IN, Sao Paulo, SP, BrazilUniv Fed Sao Paulo UNIFESP, Dept Psiquiatria, Sao Paulo, SP, BrazilWeb of Scienc

Prevalência de mastocitomas diagnosticados no Setor de Patologia Veterinária da FAVET-UFRGS de out/98 a jul/02

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Kombucha à base de Hibiscus sabdariffa L: avaliação tecnológica para produção de uma nova bebida / Kombucha based Hibiscus sabdariffa L: technological assessment for the production of a new beverage

O Kombucha é uma bebida resultante da fermentação de chá com açúcar por bactérias e leveduras presentes em uma membrana celulósica denominada de SCOBY. O objetivo do trabalho foi desenvolver e avaliar uma bebida Kombucha à base de chá de Hibisco. Os parâmetros de processo (tempo, temperatura e quantidade de SCOBY) foram determinados utilizando-se um planejamento experimental. Foi avaliada a capacidade antioxidante (DPPH, compostos fenólicos, flavonoides e antocianinas). Também, foram realizadas as análises (pH, acidez, sólidos solúveis totais e cor instrumental). Os resultados obtidos foram tratados estatisticamente por meio da Análise de Variância (ANOVA) e comparadas pelo teste de Tukey com nível de significância de 5% (p ? 0,05). A melhor formulação foi definida levando em consideração o teor antioxidante (DPPH), sendo esta a condição dos parâmetros mínimos para as três variáveis do planejamento: tempo de 2 dias; temperatura de 18 º C e quantidade de SCOBY de 10 g/L, tal formulação resultou em um produto mais ácido (0,203 % ac. Cítrico), em média com 14 ºBrix e avermelhado (a*=16). Assim, os parâmetros avaliados foram viáveis para obtenção uma bebida fermentada (Kombucha de hibisco) com alto teor antioxidante. 

Effect of Low-Input Organic and Conventional Farming Systems on Maize Rhizosphere in Two Portuguese Open-Pollinated Varieties (OPV), “Pigarro” (Improved Landrace) and “SinPre” (a Composite Cross Population)

Maize is one of the most important crops worldwide and is the number one arable crop in Portugal. A transition from the conventional farming system to organic agriculture requires optimization of cultivars and management, the interaction of plant–soil rhizosphere microbiota being pivotal. The objectives of this study were to unravel the effect of population genotype and farming system on microbial communities in the rhizosphere of maize. Rhizosphere soil samples of two open-pollinated maize populations (“SinPre” and “Pigarro”) cultivated under conventional and organic farming systems were taken during flowering and analyzed by next-generation sequencing (NGS). Phenological data were collected from the replicated field trial. A total of 266 fungi and 317 bacteria genera were identified in “SinPre” and “Pigarro” populations, of which 186 (69.9%) and 277 (87.4%) were shared among them. The microbiota of “Pigarro” showed a significant higher (P < 0.05) average abundance than the microbiota of “SinPre.” The farming system had a statistically significant impact (P < 0.05) on the soil rhizosphere microbiota, and several fungal and bacterial taxa were found to be farming system-specific. The rhizosphere microbiota diversity in the organic farming system was higher than that in the conventional system for both varieties. The presence of arbuscular mycorrhizae (Glomeromycota) was mainly detected in the microbiota of the “SinPre” population under the organic farming systems and very rare under conventional systems. A detailed metagenome function prediction was performed. At the fungal level, pathotroph–saprotroph and pathotroph–symbiotroph lifestyles were modified by the farming system. For bacterial microbiota, the main functions altered by the farming system were membrane transport, transcription, translation, cell motility, and signal transduction. This study allowed identifying groups of microorganisms known for their role as plant growth-promoting rhizobacteria (PGPR) and with the capacity to improve crop tolerance for stress conditions, allowing to minimize the use of synthetic fertilizers and pesticides. Arbuscular mycorrhizae (phyla Glomeromycota) were among the most important functional groups in the fungal microbiota and Achromobacter, Burkholderia, Erwinia, Lysinibacillus, Paenibacillus, Pseudomonas, and Stenotrophomonas in the bacterial microbiota. In this perspective, the potential role of these microorganisms will be explored in future research

Analyses Of The Rhizosphere Microbiota In Three Different Crop Systems (Conventional, Organic And Syntropic Agriculture), Using A Portuguese Maize Population And Ccp (‘Pigarro’ And ‘Sinpre’).

Maize is one of the most important crops in the world for feed and food, which makes its contribution to organic farming crucial. The adaptation to organic agriculture can depend on the interaction between the microbiota present in the rhizosphere, allowing a more efficient extraction of nutrients from the soil for growth and development.The aim of our study was to understand how different production systems (conventional, organic) and different open-pollinated maize populations (‘SinPre’ and ‘Pigarro’) can influence the rhizosphere microbiota.The data collected from the maize trial comprehends phenological data plus the structural diversity of the bacterial and fungal communities from the maize rhizosphere.Three replicates of three plants by two maize populations were collected for each cultivation system, at a depth of approximately 15 cm, forming a total of 15 composite samples. The bacterial microbiota was determined from DNA extracted from maize rhizosphere samples based on the V3-V4 region of the bacterial 16S rRNA and from ITS2 region of the fungal ITS gene using Illumina’s MiSeq sequencing.From our results, we can conclude that the farming system has an impact on fungal diversity since a higher diversity was found in organic farming systems when compared with the conventional. In addition, the fungal microbiota was more diverse in ‘Pigarro’ rhizosphere in comparison with ‘SinPre’.Comparing the diversity between ‘Pigarro and ‘SinPre’ bacterial populations, the first presented always the highest number of genera despite the farming system. Contrarily to what we observed for the fungal diversity, the number of shared bacteria was similar in both farming systems.The main conclusion was that the farming systems have significant impact in maize rhizosphere microbiota. In addition, the maize rhizosphere microbiota is population specific