Oxidative stress and immunologic responses following a dietary exposure to PAHs in Mya arenaria

<p>Abstract</p> <p>Background</p> <p>The aim of this research was to investigate oxidative stress and immune responses following a dietary polycyclic aromatic hydrocarbon (PAH) exposure in a marine bioindicator organism, the soft shell clam, <it>Mya arenaria</it>. Immune parameters in hemolymph (haemocyte number, efficiency of phagocytosis and haemocyte activity) and assessment of oxidative stress using catalase (CAT) activity and levels of malondialdehyde (MDA) performed on the digestive gland were estimated as biomarkers in clams fed in mesocosm with PAH contaminated phytoplankton. MDA levels and CAT activities were also measured <it>in situ </it>in organisms sampled in a control site (Metis Beach, Québec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-Père, Québec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters.</p> <p>Results</p> <p>Results on immune parameters suggest that the PAHs may interfere with the maturation and/or differentiation processes of haemocytes. MDA results showed that lipid peroxidation did not occur following the exposure. The levels of CAT activity corresponded to weak antioxidant activity (no significant differences). Recovery was noted for all the immune endpoints at the end of the experiment.</p> <p>Conclusion</p> <p>Results suggest that immune parameters are early biomarkers that can efficiently detect a physiological change during a short term exposure to low concentrations of PAHs. The <it>in situ </it>survey (in the natural environment) suggested that clams from the Pointe-au-Père site did not show any oxidative stress as well as the clams contaminated in mesocosm, probably due to the low concentrations of PAHs used for this study. MDA levels increased however in organisms from Metis Beach, a response probably related to domestic effluents or parasitism.</p

Efeito da atividade física no osso normal e na prevenção e tratamento da osteoporose Efectos de la actividad física en huesos normales y en la prevención y tratamiento de osteoporosis Effect of the physical activity on normal bone and on the osteoporosis prevention and treatment

A osteoporose é uma doença cada vez mais diagnosticada em mulheres e homens de todo o mundo. Embora os esteróides sexuais sejam importantes na gênese da osteoporose, a inatividade física constitui um fator de risco. O exercício físico atua no osso por efeito direto, via força mecânica, ou indireto, mediado por fatores hormonais. Mas os mecanismos pelos quais a atividade física melhora a massa óssea ainda não são totalmente conhecidos. Baseando-se nos resultados que demonstram os efeitos benéficos da atividade física no tecido ósseo, a prática de esportes vem sendo cada vez mais indicada na prevenção e até mesmo no tratamento da osteoporose. O objetivo desta revisão é descrever os efeitos da atividade física no tecido ósseo normal e na prevenção e tratamento da osteoporose.<br>La osteoporosis es una enfermedad que cada vez más se diagnostica en mujeres y hombres de todo el mundo. Aunque los esteroides sexuales sean importantes en la génesis de la osteoporosis, la inactividad física constituye un factor de riesgo. El ejercicio físico actúa en el hueso de forma directa, vía fuerza mecánica, o indirecta, mediado por factores hormonales. Sin embargo la patogénesis por la que la actividad física mejora la masa ósea todavía no es totalmente conocida. Con base en los resultados que demuestran los efectos benéficos de la actividad física en el tejido óseo, la práctica de deportes viene siendo indicada cada vez más como medio de prevención y hasta incluso como tratamiento de la osteoporosis. El objetivo de esta revisión es describir los efectos de la actividad física en el tejido óseo normal y en la prevención y tratamiento de la osteoporosis.<br>Osteoporosis has been increasingly diagnosed in women and men worldwide. Although the sexual steroids are important in the genesis of human osteoporosis, it is believed that the lack of physical activity constitutes a risk factor. Physical activity acts on the bone by direct effect via mechanical force, or indirect effect through hormonal factors. However, the mechanism through which physical activity improves the bone mass is not completely known. Sports practice has been increasingly recommended for prevention and even treatment of osteoporosis based on the results that have demonstrated the beneficial effects of physical activity on the bone tissue. The goal of this review is to describe the effects of physical activity in the normal bone tissue and on the osteoporosis prevention and treatment