In this work, the mechanical propertied of calcification in diseased coronary artery was evaluated with atomic force microscope (AFM). The heavily calcified coronary artery was harvest from a cadaver’s heart. The artery slices with thickness of 10 um were prepared with cryosectioning. Staining with Alizarin Red has been performed to highlight the calcification region. Results have shown that the calcified areas have a significant larger stiffness compared with the surrounding plaque and the media layer of a healthy artery. The calcification showed a heterogeneous property with larger deviation in stiffness distribution. The staining process affected the mechanical properties. Results will enhance the mechanical property database in the literature.

Introdução: A aprendizagem interpares é uma ferramenta educacional diferenciada, incluindo o modelo tradicional de tutoria e a interação de indivíduos com o mesmo grau de formação. O programa de formação especializada em medicina geral e familiar (MGF) introduziu, em 2019, a aprendizagem relacional no horário semanal dos médicos internos. Na Administração Região de Saúde de Lisboa e Vale do Tejo (ARSLVT) foi adotado o modelo das Sessões de Aprendizagem Relacional (SAR). O presente estudo procurou perceber como está a ser implementada esta prática em Portugal continental, de forma a promover adaptações que permitam alcançar todo o seu potencial. Métodos: Foram incluídos os internos do 54º grupo da formação especializada em MGF. Os dados foram recolhidos entre 12/nov e 12/dez de 2020, através de um questionário online divulgado por correio eletrónico pelas coordenações do Internato Médico de MGF (CIMGF). Resultados: De um total de 416 internos obtiveram-se 86 respostas, 60 das quais da ARSLVT. À data da recolha dos dados verificou‑se que na ARS Norte não tinha sido implementado qualquer modelo formal de aprendizagem relacional. Na ARSLVT apenas um ACeS não realizava SAR. Nas ARS Centro, Alentejo e Algarve, esta prática não era uniforme. Nas SAR implementadas parecem desenvolver-se diversas atividades, o planeamento é maioritariamente feito de acordo com as orientações publicadas e a maioria dos internos reconhece a sua utilidade. São apontadas como principais dificuldades o impacto na atividade assistencial, a distância entre unidades e a ausência de apoio da direção de internato. A adoção de um horário rotativo, a implementação de sessões online e a existência de documentos orientadores são possíveis soluções. Conclusão: Tendo em vista a harmonização do percurso e a igualdade de oportunidades formativas devem ser procuradas estratégias locais efetivas para que a aprendizagem relacional seja uma realidade profícua para todos os internos.

In this work, we provide a correction factor for quantifying the mechanical properties of soft biomaterials at the microscale with indentation test. Finite element (FE) models were developed to analyze the indentation test on the thin collagen layer. Based on the experiment setup, the indenter was simulated as a rigid flat-ended square indenter, the sample was simulated as a thin layer. The square indenter has a size of 2 × 2 mm and 3 × 3 mm, separately. For each indenter, the transverse dimension of the sample increased from smaller than the indenter size to 10 times the indenter size to quantify the relationship between the true stiffness and the nominal stiffness. Results have shown as the transverse dimension of the sample increased the correction factor increased from 1 when sample size less than indenter size, to 2.1 when sample size reaches 2.5 times of indenter size. For the sample thickness less than the indenter size, and transverse dimension larger than 2.5 times of the indenter size, a correction factor of 2.1 is suggested to determine the stiffness of the sample based on the force-displacement curve. These findings are independent of the material stiffness, allowing this approach to be generalized to test any soft sample.

This study was designed to connect aortic stiffness to vascular contraction in young male and female Wistar rats. We hypothesized that female animals display reduced intrinsic media-layer stiffness, which associates with improved vascular function. Atomic force microscopy (AFM)-based nanoindentation analysis was used to derive stiffness (Young’s modulus) in biaxially (i.e., longitudinal and circumferential) unloaded aortic rings. Reactivity studies compatible with uniaxial loading (i.e., circumferential) were used to assess vascular responses to a selective α1 adrenergic receptor agonist in the presence or absence of extracellular calcium. Elastin and collagen levels were indirectly evaluated with fluorescence microscopy and a picrosirius red staining kit, respectively. We report that male and female Wistar rats display similar AFM-derived aortic media-layer stiffness, even though female animals withstand higher aortic intima-media thickness-to-diameter ratio than males. Female animals also present reduced phenylephrine-induced aortic force development in concentration-response and time-force curves. Specifically, we observed impaired force displacement in both parts of the contraction curve (Aphasic and Atonic) in experiments conducted with and without extracellular calcium. Additionally, collagen levels were lower in female animals without significant elastin content and fragmentation changes. In summary, sex-related functional differences in isolated aortas appear to be related to dissimilarities in the dynamics of vascular reactivity and extracellular matrix composition rather than a direct response to a shift in intrinsic media-layer stiffness.