RESUMO
Given the recently proposed three-filament theory of muscle contraction, we present a low-cost physical sarcomere model aimed at illustrating the role of titin in the production of active force in skeletal muscle. With inexpensive materials, it is possible to illustrate actin-myosin cross-bridge interactions between the thick and thin filaments and demonstrate the two different mechanisms by which titin is thought to contribute to active and passive muscle force. Specifically, the model illustrates how titin, a molecule with springlike properties, may increase its stiffness by binding free calcium upon muscle activation and reducing its extensible length by attaching itself to actin, resulting in the greater force-generating capacity after an active than a passive elongation that has been observed experimentally. The model is simple to build and manipulate, and demonstration to high school students was shown to result in positive perception and improved understanding of the otherwise complex titin-related mechanisms of force production in skeletal and cardiac muscles.NEW & NOTEWORTHY Our physical sarcomere model illustrates not only the classic view of muscle contraction, the sliding filament and cross-bridge theories, but also the newly discovered role of titin in force regulation, called the three-filament theory. The model allows for easy visualization of the role of titin in muscle contraction and aids in explaining complex muscle properties that are not captured by the traditional cross-bridge theory.
Assuntos
Actinas , Sarcômeros , Humanos , Sarcômeros/fisiologia , Conectina/metabolismo , Contração Muscular/fisiologia , Músculo EsqueléticoRESUMO
BACKGROUND: In the global effort to discover biomarkers for cancer prognosis, prediction tools have become essential resources. TCR (T cell receptor) repertoires contain important features that differentiate healthy controls from cancer patients or differentiate outcomes for patients being treated with different drugs. Considering, tools that can easily and quickly generate and identify important features out of TCR repertoire data and build accurate classifiers to predict future outcomes are essential. RESULTS: This paper introduces GENTLE (GENerator of T cell receptor repertoire features for machine LEarning): an open-source, user-friendly web-application tool that allows TCR repertoire researchers to discover important features; to create classifier models and evaluate them with metrics; and to quickly generate visualizations for data interpretations. We performed a case study with repertoires of TRegs (regulatory T cells) and TConvs (conventional T cells) from healthy controls versus patients with breast cancer. We showed that diversity features were able to distinguish between the groups. Moreover, the classifiers built with these features could correctly classify samples ('Healthy' or 'Breast Cancer')from the TRegs repertoire when trained with the TConvs repertoire, and from the TConvs repertoire when trained with the TRegs repertoire. CONCLUSION: The paper walks through installing and using GENTLE and presents a case study and results to demonstrate the application's utility. GENTLE is geared towards any researcher working with TCR repertoire data and aims to discover predictive features from these data and build accurate classifiers. GENTLE is available on https://github.com/dhiego22/gentle and https://share.streamlit.io/dhiego22/gentle/main/gentle.py .
Assuntos
Neoplasias da Mama , Linfócitos T , Humanos , Feminino , Receptores de Antígenos de Linfócitos T/genética , Software , Aprendizado de MáquinaRESUMO
Neste estudo almejou-se traduzir, adaptar e buscar evidências de validade baseadas na estrutura interna e na relação com uma variável externa convergente para a Escala de Autoeficácia para Autorregulação da Escrita (EAARE) no contexto brasileiro. Trata-se de uma escala que avalia a percepção de capacidade do estudante em executar habilidades específicas de escrita. Participaram da pesquisa 430 universitários, que responderam à EAARE e a outra medida de aferição da crença de autoeficácia na escrita. A análise fatorial indicou a presença de uma única dimensão, cujo índice de consistência interna foi de 0,95. Em convergência com a literatura e com as expectativas formuladas, os resultados também apontaram uma relação estatisticamente significativa, forte e positiva entre os escores das duas escalas utilizadas. Desse modo, pode-se afirmar que a EAARE se constitui como um instrumento com evidências de validade e de fidedignidade apropriados para o uso no contexto brasileiro. (AU)
This validation study aimed at the translation, adaptation, and presentation of the Self-Efficacy Scale for Self-Regulated Writing (EAARE) in the Brazilian context based on its internal structure and relation with a convergent external variable. This scale assesses students' perception of their ability to perform specific writing skills. A total of 430 undergraduates participated in the study answering the EAARE and another writing self-efficacy assessment. The factor analysis indicated the presence of only one dimension with internal consistency of 0.95 and also a strong and positive relationship between the scores of the 2 scales applied in the study. These results are consistent with the literature and with the posited expectation; therefore it can be affirmed that EAARE is an instrument with proper evidence of validity and reliability to be used in the Brazilian context. (AU)
Se anheló en este estudio traducir, adaptar y buscar evidencias de validez, basadas en la estructura interior y en la relación con una variable exterior convergente, de la Escala de Autoeficacia para Autorregulación de la Escritura (EAARE) en el contexto brasileño. Se trata de una escala que evalúa la percepción de la capacidad del estudiante en ejecutar habilidades específicas de escritura. Participaron de la investigación 430 universitarios, que respondieron a la EAARE y la otra medida de evaluación de la creencia de autoeficacia en la escritura. El análisis factorial indicó la presencia de una sola dimensión, cuyo índice de consistencia interna fue 0,95. En convergencia con la literatura y con las expectativas formuladas, los resultados también señalaron una relación estadísticamente significativa, fuerte y positiva entre las puntuaciones de las dos escalas utilizadas. De este modo, se puede afirmar que la EAARE se constituye como un instrumento con evidencias de validez y de fiabilidad apropiadas para el uso en el contexto brasileño. (AU)
Assuntos
Humanos , Feminino , Adulto , Estudantes/psicologia , Autoeficácia , Escrita Manual , Tradução , Reprodutibilidade dos Testes , Análise FatorialRESUMO
El cambio educativo hacia un modelo acorde con el Espacio Europeo de Educación Superior y la aparición de nuevos entornos virtuales de aprendizaje han propiciado el desarrollo de herramientas de transmisión del conocimiento denominadas objetos de aprendizaje. El presente artículo pretende establecer una panorámica de la definición y naturaleza de estos, los repositorios existentes y los programas informáticos disponibles para su creación.
The educational change to a model in agreement with the European Space of the Higher Education (ESHE) and the appearance of new virtual learning environments allowed the development of tools of knowledge transmission called learning tools. The aim of resent paper is to establish a panorama of the definition and origin of such tools, the available repositories and the information program also available for its creation.