Ação da atividade física sobre as propriedades mecânicas dos fêmures e tíbias de ratas osteopênicas Effects of physical activity on the mechanical properties of osteopenic female rats' femurs and tibiae

Avaliamos as propriedades mecânicas, obtidas através de ensaios de flexo-compressão de fêmures e de flexão em 3 pontos de tíbias, de ratas adultas, ovariectomizadas e submetidas à atividade física. Foram utilizadas 30 ratas divididas em 3 grupos: G1: Controle. G2: Animais ovariectomizados e não submetidos a exercícios. G3: Foram treinados em uma gaiola giratória por cinco dias consecutivos, em seguida submetidos à ovariectomia, permanecendo em repouso por 24 horas. Exercitaram por 30 minutos, 5 dias por semana durante 9 semanas com velocidade de aproximadamente 0,31 m/s. Os valores obtidos de carga e de deformação evidenciaram que os fêmures das ratas ovariectomizadas apresentaram redução estatisticamente significativa nas propriedades mecânicas de carga e de deformação no limite máximo. Os fêmures do grupo ovariectomizado e submetido à prática de exercícios apresentaram valores de carga e de deformação no limite máximo superiores aos do grupo apenas ovariectomizado, no entanto, sem significância estatística. As tíbias não apresentaram alterações significativas em nenhuma das propriedades mecânicas estudadas. A atividade física aplicada por 30 minutos, 5 dias por semana durante 9 semanas a 0,31 m/s não foi suficiente para corrigir as alterações biomecânicas do tecido ósseo provocadas pela ovariectomia.<br>We evaluated the mechanical properties, obtained by means of flexion-compression assays in femurs and flexion assays on three tibial sites of ovariectomized adult female rats submitted to physical activity. Thirty rats were employed and divided into 3 groups: G1: Control. G2: Ovariectomized animals and not submitted to physical activity. G3: Animals trained in a spinning cage for five consecutive days, subsequently submitted to ovariectomy, and allowed to rest during 24 hours. The animals were submitted to physical activity for 30 minutes, 5 days a week, for a period of 9 weeks, at a speed of approximately 0.31 m/s. The values achieved for load and deformation evidenced that ovariectomized rats’ femurs presented with a statistically significant reduction on load and deformation mechanical properties, at the maximum limit. Femurs in the group submitted to ovariectomy and physical activity presented with load and deformation values at maximum limit superior to those for the group submitted only to ovariectomy, however, with no statistical significance. The tibiae didn’t present significant changes in any of the mechanical properties studied. Physical activity applied for 30 minutes, 5 days a week, during 9 weeks at 0.31 m/s was not enough to correct the biomechanical changes of bone tissue yielded by ovariectomy

Environmental assessment of organic juice imported to Denmark: a case study on oranges (Citrus sinensis) from Brazil

Growing global trade with organic products has given rise to a debate on the environmental impacts during both production and transport. Environmental hotspots of organic orange juice produced by smallholders in Brazil, processed and imported to Denmark were identified in a case study using a life cycle approach. Furthermore, small-scale organic orange production was compared with small-scale conventional and large-scale organic orange production in the case study area in Brazil. Transport was the main contributor (57%) to the global warming potential of organic orange juice from small-scale farmers imported to Denmark, followed by the processing stage (29%), especially the truck transport of fresh oranges in Brazil and of reconstituted orange juice in Europe. Non-renewable energy use per hectare was significantly lower on the organic small-scale farms than on the conventional, with a similar, although not significantly lower, pattern for global warming potential and eutrophication. Including soil carbon sequestration in organic plantations widened the difference in global warming potential between organic and conventional. Organic small-scale farms had a higher crop diversity than conventional, which may have a positive effect on biodiversity along with the spontaneous vegetation between the organic orange trees and the absence of toxic pesticides. Comparing small-scale with large-scale organic orange production, crop diversity was higher on the small-scale farms, while global warming potential, eutrophication potential and the use of copper per hectare were significantly lower, indicating that environmental impacts from small-scale differ from large-scale organic farms