Finite element modelling of hybrid stabilization systems for the human lumbar spine

Intersomatic fusion is a very popular treatment for spinal diseases associated with intervertebral disc degeneration. The effects of three different hybrid stabilization systems on both range of motion and intradiscal pressure were investigated, as there is no consensus in the literature about the efficiency of these systems. Finite element simulations were designed to predict the variations of range of motion and intradiscal pressure from intact to implanted situations. After hybrid stabilization system implantation, L4-L5 level did not lose its motion completely, while L5-S1 had no mobility as a consequence of disc removal and fusion process. BalanC hybrid stabilization system represented higher mobility at the index level, reduced intradiscal pressure of adjacent level, but caused to increment in range of motion by 20% under axial rotation. Higher tendency by 93% to the failure was also detected under axial rotation. Dynesys hybrid stabilization system represented more restricted motion than BalanC, and negligible effects to the adjacent level. B-DYN hybrid stabilization system was the most rigid one among all three systems. It reduced intradiscal pressure and range of motion at the adjacent level except from motion under axial rotation being increased by 13%. Fracture risk of B-DYN and Dynesys Transition Optima components was low when compared with BalanC. Mobility of the adjacent level around axial direction should be taken into account in case of implantation with BalanC and B-DYN systems, as well as on the development of new designs. Having these findings in mind, it is clear that hybrid systems need to be further tested, both clinically and numerically, before being considered for common use

Finite element modelling of the developing infant femur using paired CT and MRI scans

Bone finite element (FE) studies based on infant post-mortem computed tomography (CT) examinations are being developed to provide quantitative information to assist the differentiation between accidental and inflicted injury, and unsuspected underlying disease. As the growing skeleton contains non-ossified cartilaginous regions at the epiphyses, which are not well characterised on CT examinations, it is difficult to evaluate the mechanical behaviour of the developing whole bone. This study made use of paired paediatric post mortem femoral CT and magnetic resonance imaging (MRI) examinations at two different stages of development (4 and 7 months) to provide anatomical and constitutive information for both hard and soft tissues. The work aimed to evaluate the effect of epiphyseal ossification on the propensity to shaft fractures in infants. The outcomes suggest that the failure load of the femoral diaphysis in the models incorporating the non-ossified epiphysis is within the range of bone-only FE models. There may however be an effect on the metaphysis. Confirmation of these findings is required in a larger cohort of children

Controle de larvas de Boophilus microplus por Metarhizium anisopliae em pastagens infestadas artificialmente Control of Boophilus microplus larvae by Metarhizium anisopliae in artificially infested pastures

O objetivo deste trabalho foi avaliar a eficiência do controle exercido por Metarhizium anisopliae na população de Boophilus microplus, em pastagens de Brachiaria brizantha, e do híbrido Tifton 85 (Cynodon spp.), artificialmente infestadas com fêmeas ingurgitadas do carrapato. Trinta canteiros com 1 m² de área cada foram distribuídos aleatoriamente. Quinze foram pulverizados com esporos do fungo e quinze controles em cada forrageira, constituindo cinco repetições de cada tratamento, foram infestados com número e peso padronizados de fêmeas ingurgitadas do ácaro. Aplicou-se o fungo, na concentração de 1,8x10(8) conídios mL-1, em três situações: pulverização antes da infestação com o carrapato, após a infestação e posterioriormente à emergência das primeiras larvas nos capins. A ação do fungo foi avaliada no 35º, 38º, 41º, 48º, 55º e 61º dia pós-infestação, por meio da contagem de larvas recuperadas. Obteve-se controle de larvas do ácaro, que, nas avaliações realizadas entre o 35º e o 48º dia pós-infestação, variou entre 87% e 94%. As médias das contagens de estágios larvares do carrapato foram menores em todas as amostragens realizadas no capim-Tifton 85, indicando que houve efeito da pastagem na ação do fungo. A situação de aplicação influencia a atividade do fungo, com melhor resultado nas coletas realizadas entre o 41º e 55º dia após infestação em B. brizantha, e aplicação dos conídios logo após a emergência das primeiras larvas.<br>The objective of this work was to evaluate the efficiency of Metarhizium anisopliae fungus against Boophilus microplus population in Brachiaria brizantha and Tifton 85 (Cynodon) pastures, artificially infested with tick engorged females. Thirty plots of 1 m² each were randomly distributed in fifteen treated and fifteen control groups per type of grass, establishing five repetitions for each treatment. Pastures were infested with engorged tick females standardized by number and weight. Metarhizium anisopliae suspension with 1.8x10(8) conidia mL-1 concentration was sprayed on the plot in three different assays, prior infested with tick females, immediately after tick inoculation and at first larvae emergency. The fungus action was evaluated at 35th, 38th, 41st, 48th, 55th and 61st day post infestation by counting recovered larvae. A significative reduction of larvae counts occurred in fungus treated groups during 35th to 48th day post infestation, ranging between 87% and 94% of efficacy on tick larvae control. The mean values for larvae counting in Tifton 85 pasture were lower than in B. brizantha plot in all analysis, suggesting the pasture effect on fungus action. Treatment strategy influenced on M. anisopliae activity, which demonstrated better results at 41st and 55th day post infestation in B. brizantha, submitted to conidia challenge after larvae emergency

Curvature in biological systems: its quantification, emergence and implications across the scales

Surface curvature both emerges from, and influences the behavior of, living objects at length scales ranging from cell membranes to single cells to tissues and organs. The relevance of surface curvature in biology has been supported by numerous recent experimental and theoretical investigations in recent years. In this review, we first give a brief introduction to the key ideas of surface curvature in the context of biological systems and discuss the challenges that arise when measuring surface curvature. Giving an overview of the emergence of curvature in biological systems, its significance at different length scales becomes apparent. On the other hand, summarizing current findings also shows that both single cells and entire cell sheets, tissues or organisms respond to curvature by modulating their shape and their migration behavior. Finally, we address the interplay between the distribution of morphogens or micro-organisms and the emergence of curvature across length scales with examples demonstrating these key mechanistic principles of morphogenesis. Overall, this review highlights that curved interfaces are not merely a passive by-product of the chemical, biological and mechanical processes but that curvature acts also as a signal that co-determines these processes. This article is protected by copyright. All rights reserved

Satellite-derived estimation of environmental suitability for malaria vector development in Portugal

Malaria was endemic in Europe for more than two millennia until its eradication in the 1970s. Recent autochthonous cases registered in Greece have increased the awareness regarding the threat of malaria re-emergence in Southern Europe. Currently, the presence of competent vectors, suitable environmental conditions and the evidences of a changing climate may increase the widespread re-emergence of malaria in Southern Europe.This work focused on determining the current relationships between environmental factors and the density of the former malaria vector Anopheles atroparvus in Portugal, a previously endemic country. Adult females were sampled and vector density was estimated in 22 sites in Southern Portugal between 2001 and 2010 and related with land cover and satellite-derived air temperature and vegetation indices. The relationship between vector density and local larval habitat, temperature and, in a broader sense, to environmental suitability, was assessed using a statistical modelling approach.Results showed that present environmental conditions are suitable for vector development at high densities and the spatial and temporal patterns closely resemble the ones registered in the past endemic period. The use of satellite-derived data, together with statistical models, allowed the extrapolation of suitable environmental conditions for vector development from site-level to the Portuguese mainland territory. This work also improved the baseline knowledge needed to understand the potential impacts of future environmental changes on vector density and, indirectly, on the risk of malaria re-emergence