Criterios para evaluar metodologías de ensamblaje de objetos de aprendizaje

[ES]—La selección y secuenciación del material educativo digital es un trabajo que requiere de un esfuerzo importante por parte de docentes, especialistas, e incluso de estudiantes. Actualmente, se busca acompañar estas tareas a partir de procesos de ensamblaje de materiales educativos digitales, y en particular de objetos de aprendizaje. Se han comenzado a desarrollar metodologías y herramientas que soportan e implementan este proceso. Este trabajo propone profundizar en el análisis de las metodologías de ensamblaje de objetos de aprendizaje, que constituyen un tema de investigación y debate en la comunidad científica y académica. Para ello se aporta un conjunto de criterios de análisis para este tipo de metodologías, y se los aplica a una selección de 33 metodologías recopiladas. Este análisis ha permitido obtener resultados de interés en relación al estado del arte de estas estrategias de ensamblaje. En particular, se visualiza una tendencia en el desarrollo de sistemas automáticos o semiautomáticos para apoyar a docentes y alumnos en la creación de itinerarios de aprendizaje, y una baja cantidad de herramientas disponibles que implementen las metodologías revisadas. Los resultados y conclusiones de este trabajo abren las puertas para profundizar la investigación en la temática

O-polysaccharide plays a major role on the virulence and immunostimulatory potential of aggregatibacter actinomycetemcomitans during periodontal infection

Aggregatibacter actinomycetemcomitans is a Gram-negative oral bacterium with high immunostimulatory and pathogenic potential involved in the onset and progression of periodontitis, a chronic disease characterized by aberrant immune responses followed by tooth-supporting bone resorption, which eventually leads to tooth loss. While several studies have provided evidence related to the virulence factors of A. actinomycetemcomitans involved in the host cell death and immune evasion, such as its most studied primate-specific virulence factor, leukotoxin, the role of specific lipopolysaccharide (LPS) domains remain poorly understood. Here, we analyzed the role of the immunodominant domain of the LPS of A. actinomycetemcomitans termed O-polysaccharide (O-PS), which differentiates the distinct bacterial serotypes based on its antigenicity. To determine the role of the O-PS in the immunogenicity and virulence of A. actinomycetemcomitans during periodontitis, we analyzed the in vivo and in vitro effect of an O-PS-defective transposon mutant serotype b strain, characterized by the deletion of the rmlC gene encoding the alpha-L-rhamnose sugar biosynthetic enzyme. Induction of experimental periodontitis using the O-PS-defective rmlC mutant strain resulted in lower tooth-supporting bone resorption, infiltration of Th1, Th17, and Th22 lymphocytes, and expression of Ahr, Il1b, Il17, Il23, Tlr4, and RANKL (Tnfsf11) in the periodontal lesions as compared with the wild-type A. actinomycetemcomitans strain. In addition, the O-PS-defective rmlC mutant strain led to impaired activation of antigen-presenting cells, with less expression of the co-stimulatory molecules CD40 and CD80 in B lymphocytes and dendritic cells, and downregulated expression of Tnfa and Il1b in splenocytes. In conclusion, these data demonstrate that the O-PS from the serotype b of A. actinomycetemcomitans plays a key role in the capacity of the bacterium to prime oral innate and adaptive immune responses, by triggering the Th1 and Th17-driven tooth-supporting bone resorption during periodontitis.Chilean Governmental, Agencia Nacional de Investigacion y Desarrollo (ANID) FONDECYT 1181780 ANID CONICYT 2117029

¿Por qué si el agua es transparente uno ve el mar azul? Lo que se preguntan los niños sobre ciencias contestado en breves relatos de expertos

Este libro, cuyo título es precisamente una de las preguntas de los niños, una de aquellas que quizás nos hicimos cuando teníamos esas edades, nos mostró lo cerca que está la ciencia de cada uno, todas las inquietudes que se tienen sobre la misma y la oportunidad que tenemos si enriquecemos la escuela con espacios que permitan aprovechar dichas preguntas para enseñarles a pensar a nuestros niños, a despertar su curiosidad y a seguir teniendo ideas maravillosas

Loss of 5hmC identifies a new type of aberrant DNA hypermethylation in glioma.

Aberrant DNA hypermethylation is a hallmark of cancer although the underlying molecular mechanisms are still poorly understood. To study the possible role of 5-hydroxymethylcytosine (5hmC) in this process we analyzed the global and locus-specific genome-wide levels of 5hmC and 5-methylcytosine (5mC) in human primary samples from 12 non-tumoral brains and 53 gliomas. We found that the levels of 5hmC identified in non-tumoral samples were significantly reduced in gliomas. Strikingly, hypo-hydroxymethylation at 4627 (9.3%) CpG sites was associated with aberrant DNA hypermethylation and was strongly enriched in CpG island shores. The DNA regions containing these CpG sites were enriched in H3K4me2 and presented a different genuine chromatin signature to that characteristic of the genes classically aberrantly hypermethylated in cancer. As this 5mC gain is inversely correlated with loss of 5hmC and has not been identified with classical sodium bisulfite-based technologies, we conclude that our data identifies a novel 5hmC-dependent type of aberrant DNA hypermethylation in glioma

Outcomes in Newly Diagnosed Atrial Fibrillation and History of Acute Coronary Syndromes: Insights from GARFIELD-AF

BACKGROUND: Many patients with atrial fibrillation have concomitant coronary artery disease with or without acute coronary syndromes and are in need of additional antithrombotic therapy. There are few data on the long-term clinical outcome of atrial fibrillation patients with a history of acute coronary syndrome. This is a 2-year study of atrial fibrillation patients with or without a history of acute coronary syndromes