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Currently, in science teaching and in particular, natural science teaching there are concepts in the school that have a high level of abstraction. Concepts, such as atom, gene, mole and energy, among others are difficult to explain in an understanding manner to students. This situation requires the teacher to design alternative strategies to promote meaningful learning. Give priority to teaching concepts in science promotes the conception of science as a finished, infallible construct outside the context and does not evolve; turning science learning into something monotonous and uninteresting for students. According to some researches in the line of history and epistemology of sciences, its importance and advantages are recognized to promote not only a conceptual and formal education, but also to broaden the spectrum of possibilities that allow the students to transform conceptions of science into a more dynamic and participatory paradigm. Recognizing the benefits of the use of history in science teaching, a proposal is made for the DNA structure teaching in secondary school students within the framework of the Master in Teaching of Sciences of the Fundación Universidad Autónoma de Colombia, under this perspective.

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Prion diseases are fatal neurodegenerative diseases in mammals with the unique characteristics of misfolding and aggregation of the cellular prion protein (PrPC) to the scrapie prion (PrPSc). Although neuroinflammation and neuronal loss feature within the disease process, the details of PrPC/PrPSc molecular transition to generate different aggregated species, and the correlation between each species and sequence of cellular events in disease pathogenesis are not fully understood. In this study, using mice inoculated with the RML isolate of mouse-adapted scrapie as a model, we applied asymmetric flow field-flow fractionation to monitor PrPC and PrPSc particle sizes and we also measured seeding activity and resistance to proteases. For cellular analysis in brain tissue, we measured inflammatory markers and synaptic damage, and used the isotropic fractionator to measure neuronal loss; these techniques were applied at different timepoints in a cross-sectional study of disease progression. Our analyses align with previous reports defining significant decreases in PrPC levels at pre-clinical stages of the disease and demonstrate that these decreases become significant before neuronal loss. We also identified the earliest PrPSc assemblies at a timepoint equivalent to 40% elapsed time for the disease incubation period; we propose that these assemblies, mostly composed of proteinase K (PK)–sensitive species, play an important role in triggering disease pathogenesis. Lastly, we show that the PK-resistant assemblies of PrPSc that appear at timepoints close to the terminal stage have similar biophysical characteristics, and hence that preparative use of PK-digestion selects for this specific subpopulation. In sum, our data argue that qualitative, as well as quantitative, changes in PrP conformers occur at the midpoint of subclinical phase; these changes affect quaternary structure and may occur at the threshold where adaptive responses become inadequate to deal with pathogenic processes. [ABSTRACT FROM AUTHOR]

Nowadays there is an emerging interest on health system resilience capacity during emergencies as the one created by the COVID-19 Pandemic. This article contributes to this emerging field of studies by analysing the impact of the state´s policy responses COVID-19 (as lockdowns) on the Peruvian health system, specifically on the delivery of non-covid services, sexual and reproductive health services, and describe the strategies deployed by health workers to adapt to the COVID-19 crisis in Peru, a country that have been dramatically impacted by the pandemic. The article, based on the analysis of depth interviews with 11 health workers and one health supervisor working at sexual and reproductive health services at public health services Lima during 2020 and 2021, describe how pre-existing conditions of the health system (as poor infrastructure and deficit of human resources) magnified the negative effects of the measures taken to control de pandemic, undermining the "resilience" of the health system., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Gianella et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)