102,621 research outputs found
Happy children! A network of psychological and environmental factors associated with the development of positive affect in 9–13 children
No full text: To deepen the development of positive affect during early adolescence and shed new light on its predictors, this study adopts an exploratory network approach to first identify the main domains that describe the variability of children's psychological, environmental, and behavioral characteristics, and then use these domains to longitudinally predict positive affect and its development within a latent growth framework. To this aim, we considered 10,904 US participants (9 years old at baseline; 13 years old 42 months later), six measurement occasions of positive affect, and 46 baseline indicators from the ABCD study. Our results not only confirm that positive affect declines between 9 and 13 years old, but also show that among the five domains identified (behavioral dysregulation, cognitive functioning, psychological problems, supportive social environment, and extracurricular activities), only a supportive social environment consistently predicts positive affect. This is crucial for practitioners and policymakers, as it can help them focus on the elements within our complex network of psychological, social, and environmental variability
Caracterização dos efeitos biológicos das lectinas de Canavalia brasiliensis (ConBr) e de Canavalia ensiformes (ConA) em preparações do sistema nervoso central e em células tumorais
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciencias Biológicas. Programa de Pós-Graduação em Neurociências.Lectinas são proteínas com especificidade de ligação à resíduos de carboidratos. ConBr e ConA são lectinas com especificidade para D-glicose/D-manose, extraídas de plantas, família Leguminosae, tribo Phaseolae, subtribo Diocleinae. Estas lectinas podem estimular a proliferação de linfócitos e produção de interferon , ativar macrófagos e produzir inflamação, além de induzirem apoptose em vários tipos celulares. Apesar destes efeitos, existem poucos estudos das ações destas lectinas sobre células tumorais e sobre preparações neurais, especialmente sobre os mecanismos de sinalização celular envolvidos na regulação da neurotransmisssão, diferenciação, proliferação e morte celular. O presente trabalho tem como objetivos: a) determinar as possíveis ações de ConBr e ConA sobre a viabilidade e modulação da liberação do neurotransmissor glutamato no terminal sináptico (sinaptossoma); b) determinar possíveis ações destas lectinas sobre a viabilidade celular em fatias hipocampais, em células de linhagens tumorais de glioma C6 e mieloleucêmicas U-937; c) determinar ações dessas lectinas sobre a via de sinalização de proteínas quinases ativadas por mitógenos (MAPKs) nestas preparações. ConBr e ConA (5-100 g/ml) foram incubadas (1-5min) com sinaptossomas ou fatias hipocampais obtidas de ratas adultas (60-70dias). Além disso, estas lectinas (0,5-100 g/ml) foram incubadas por 24-48h com linhagens tumorais de glioma C6 ou mieloleucêmicas U-937. Os testes de viabilidade foram realizados através de medidas da liberação de LDH ou da redução do MTT. A liberação de 3H-glutamato foi medida através de cintilação líquida. A modulação das vias de MAPKs foi avaliada através de Western blotting usando anticorpos contra as formas fosforiladas e totais de ERK1/2, JNK1/2 e p38MAPK. Os resultados mostraram que ConA e ConBr não alteraram a viabilidade e nem a liberação basal de L-[3H]glutamato em sinaptossomas. -Latrotoxina 1nM sozinha aumentou 43% da liberação de L-[3H]-glutamato em relação ao controle e ConBr provocou um incremento significativo de 20% no efeito de -latrotoxina. E em sinaptossomas, a ConBr mas não ConA estimulou ERK1/2. Estas lectinas não alteraram a viabilidade celular e nem a fosforilação de MAPKs em fatias hipocampais. ConA e ConBr diminuiram fortemente a viabilidade celular em linhagens de glioma C6, sendo este efeito acompanhado de redução da fosforilação de ERK1/2. Nas células mieloleucêmicas U-937, ConBr causou uma redução de viabilidade significativa. Apesar da alta homologia estrutural entre ConA e ConBr estas lectinas apresentaram variações em alguns efeitos biológicos. Os resultados descrevem de forma inédita a modulação, por ConBr, da liberação de glutamato e de MAPKs em sinaptossomas. Adicionalmente, demonstram uma ação de ConBr e ConA na morte celular e/ou inibição de proliferação celular em linhagens tumorais. Em conjunto os dados sugerem ConBr como uma possível ferramenta para estudo da transmissão sináptica e ConBr e ConA como potenciais ferramentas para estudo de processos relacionados a morte celular em células tumorais
Convergence on Kirk Iteration of Cesàro Means for Asymptotically Nonexpansive Mappings
No full textThis article addresses the convergence of iteration sequences in Cesàro means for asymptotically nonexpansive mappings. Specifically, this study explores the behavior of Kirk iteration in the Cesàro means in the context of uniformly convex and reflexive Banach spaces equipped with uniformly Gâteaux differentiable norms. The focus is to determine the conditions under which the Kirk iteration sequence converges strongly or weakly to a fixed point. Finally, some examples are given in this article to demonstrate the advantages of the preferred iteration method and to verify the results obtained
Tyrosine phosphorylation mediates ConA-induced membrane type 1-matrix metalloproteinase expression and matrix metalloproteinase-2 activation in MDA-MB-231 human breast carcinoma cells
No full textConA-induced cell surface activation of pro-matrix metalloproteinase-2 (pro-MMP-2) by MDA-MB-231 human breast cancer cells is apparently mediated by up-regulation of membrane type 1 MMP (MT1-MMP) through transcriptional and posttranscriptional mechanisms. Here, we have explored the respective roles of cell surface clustering and protein tyrosine phosphorylation in the ConA- induction effects. Treatment with succinyl-ConA, a variant lacking significant clusterability, partially stimulated MT1-MMP mRNA and protein levels but did not induce MMP-2 activation, suggesting that clustering contributes to the transcriptional regulation by ConA but appears to be critical for the nontranscriptional component. We further found that genistein, an inhibitor of tyrosine phosphorylation, blocked ConA-induced pro-MMP-2 activation and ConA-induced MT1-MMP mRNA level in a dose-dependent manner, implicating tyrosine phosphorylation in the transcriptional aspect. This was confirmed by the dose-dependent promotion of pro-MMP-2 activation by sodium orthovanadate in the presence of suboptimal concentrations of ConA (7.5 μg/ml), with optimal effects seen at 25 μg/g orthovanadate. Genistein did not inhibit the ConA potentiation of MMP-2 activation in MCF-7 cells, in which transfected MT1-MMP is driven by a heterologous promoter, supporting the major implication of phosphotyrosine in the transcriptional component of ConA regulation. These data describe a major signaling event upstream of MT1- MMP induction by ConA and set the stage for further analysis of the nontranscriptional component
Processes of response facilitation and inhibition in the Simon task. A single-pulse transcranial magnetic stimulation (TMS) study
No full textIs cognitive control automatic? New insights from transcranial magnetic stimulation
No full textCognitive control has been classically considered as a flexible process engaged to pursue intentional behaviors, as distinct from automatic processes, which are unintentional, inflexible, and triggered by unconscious mechanisms. Our study challenged this view, showing that such a distinction may not be so clear-cut. We analyzed motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation to investigate the neurocognitive mechanisms occurring in a conflict task during trials that either required or did not require a response. We observed a Simon effect on MEPs and sequential modulations of such effects on both kinds of trials. Sequential modulations are usually explained as resulting from the engagement of intentional control mechanisms. Our findings rule against this idea, suggesting that these effects are the result of a mechanism that detects and resolves conflict even when there is no intention to select any response. Accordingly, cognitive control also seems to operate without intention, acting in an automatic fashio
Transcranial random noise stimulation (tRNS): a wide range of frequencies is needed for increasing cortical excitability
No full textTranscranial random noise stimulation (tRNS) is a recent neuromodulation protocol. The high-frequency band (hf-tRNS) has shown to be the most effective in enhancing neural excitability. The frequency band of hf-tRNS typically spans from 100 to 640 Hz. Here we asked whether both the lower and the higher half of the high-frequency band are needed for increasing neural excitability. Three frequency ranges (100–400 Hz, 400–700 Hz, 100–700 Hz) and Sham conditions were delivered for 10 minutes at an intensity of 1.5 mA over the primary motor cortex (M1). Single-pulse transcranial magnetic stimulation (TMS) was delivered over the same area at baseline, 0, 10, 20, 30, 45 and 60 minutes after stimulation, while motor evoked potentials (MEPs) were recorded to evaluate changes in cortical excitability. Only the full-band condition (100–700 Hz) was able to modulate excitability by enhancing MEPs at 10 and 20 minutes after stimulation: neither the higher nor the lower sub-range of the high-frequency band significantly modulated cortical excitability. These results show that the efficacy of tRNS is strictly related to the width of the selected frequency range
Thinking about it: the impact of COVID-19-related stimuli on prospective memory
No full textBackground. Since 2020, information regarding COVID-19 has been a constant presence in the news, in our conversations and thoughts. Continuous exposure to this type of stimuli could have an impact on cognitive processes essential for our everyday activities, such as prospective memory (PM). PM is the ability to remember to perform an intention at a specific point in the future, like remembering to take prescribed medicines at a specific time or to turn off the stove after cooking. Do COVID-related stimuli affect our ability to perform a PM task? Methods. To answer this question, we proposed a novel version of the classical paradigm used to investigate PM. Namely, this paradigm includes a baseline condition, in which an ongoing task is presented alone, and a PM condition in which the same task is proposed again together with a second (prospective) task. In this study, a short video clip was presented between the baseline and the PM condition. The video clip displayed either neutral, negative, or COVID-related content. Additionally, participants were asked to respond to two questionnaires and a series of questions regarding their well-being and experience with the pandemic. Namely, the DASS-21 scale (evaluating depression, anxiety, and stress), and the COVID-19-PTSD questionnaire (a questionnaire evaluating post-traumatic stress disorder symptoms related to the pandemic experience) were administered. Participants’ performance and responses were analyzed using a linear mixed effect (LME) model approach, and correlation analyses were run to highlight possible correlations between participants’ scores in the DASS-21, the COVID-19-PTSD, and the additional questions on their personal experience with the pandemic. Results. The LME models revealed significant effects of the displayed video on performance: in line with previous studies, the clip displaying standard negative contents led to impaired accuracy in the ongoing task in the PM condition, compared to the Baseline. In contrast, participants who saw the COVID-related clip showed improved accuracy in the ongoing task compared to the other participants, selectively in the block performed after the video clip was displayed (PM condition). Furthermore, the explanatory power of the LME model calculated on accuracy to the ongoing trials was enhanced by the inclusion of the scores in the anxiety subscale of the DASS-21, suggesting a detrimental role of anxiety. Altogether, these results indicate a different effect of the exposure to classical negative contents (associated with a cost in terms of accuracy in the ongoing task between the baseline and the PM condition) and the pandemic-related one, which was instead characterized by a higher accuracy to ongoing trials compared to the other video clips. This counterintuitive finding seems to suggest that COVID-related stimuli are processed as ``acute stressors'' rather than negative stimuli, thus inducing a state of increased alertness and responsivity
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