Pathomechanics of posterior ankle impingement syndrome in female ballet dancers

A dança é uma actividade de grande exigência atlética, que pode conduzir a um elevado número de lesões, particularmente na região do tornozelo, possivelmente devido à amplitude extrema do movimento articular de flexão plantar do mesmo, que os bailarinos, especialmente do sexo feminino possuem, para realizar a ponta e meia ponta tão características do ballet clássico (Kadel, 2006; Motta-Valencia, 2006; Russel, Kruse, Koutedakis, McEwan, Wyon, 2010). Estas posições de flexão plantar extrema produzem força excessiva na região posterior do tornozelo, o que muitas vezes pode resultar em conflito, dor e incapacidade, representando na maioria das vezes um desafio de diagnóstico. O síndrome do conflito posterior do tornozelo refere-se a um grupo de entidades patológicas que resultam da flexão plantar forçada do tornozelo, de forma repetitiva ou traumática, causando um conflito das estruturas ósseas e/ou de tecidos moles (Hamilton, Geppert, Thompson, 1996; Hamilton, 2008) . Os objectivos deste projecto são compreender os quais os factores de risco, mecânicos e funcionais que contribuem para a mecânica patológica da lesão descritos na literatura, e proceder a uma avaliação biomecânica do movimento de flexão plantar do tornozelo. Método. Realizar uma revisão sistemática de literatura dirigida á mecânica patológica do síndrome do conflito posterior do tornozelo em bailarinas e conduzir um estudo caso-controlo, cujo objectivo é avaliar, comparar e descrever o movimento da flexão plantar do tornozelo realizado ao efectuar os movimentos de ponta e meia-ponta, em bailarinas pré-profissionais com e sem lesão recorrente resultante do conflito posterior do tornozelo. Resultados. Não foram encontrados estudos relacionados especificamente com a mecânica patológica do tornozelo, no entanto vários estudos foram encontrados considerando as características clínicas e anatómicas assim como os procedimentos de tratamento, indicando que os principais factores de risco relacionados com a lesão se dividem em factores mecânicos e funcionais que quando combinados entre si e associados ao sobre-uso podem resultar no conflito posterior do tornozelo. Na avaliação do movimento foram observadas diferenças na actividade muscular entre os sujeitos com lesão e controlos, tendo sido possível a observação de um padrão na sequência de activação para um dos movimentos testados. Na oscilação postural e na rigidez do tornozelo foram também observadas diferenças entre os sujeitos bem como entre as posições realizadas. Conclusão. Concluiu-se que não sendo possível alterar a anatomia do bailarino, por vezes é possível intervir a nível funcional melhorando a capacidade técnica de forma obter um melhor desempenho e a actuar preventivamente em relação às lesões, uma vez que estas podem apresentar padrões cinéticos próprios, relacionados com a função muscular, a estabilidade postural e a rigidez articular.

Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

The effort expended on reproduction may entail future costs, such as reduced survival or fecundity, and these costs can have an important influence on life-history optimization. For birds with precocial offspring, hypothesized costs of reproduction have typically emphasized nutritional and energetic investments in egg formation and incubation. We measured seasonal survival of 3856 radio-marked female Mallards (Anas platyrhynchos) from arrival on the breeding grounds through brood-rearing or cessation of breeding. There was a 2.5-fold direct increase in mortality risk associated with incubating nests in terrestrial habitats, whereas during brood-rearing when breeding females occupy aquatic habitats, mortality risk reached seasonal lows. Mortality risk also varied with calendar date and was highest during periods when large numbers of Mallards were nesting, suggesting that prey-switching behaviors by common predators may exacerbate risks to adults in all breeding stages. Although prior investments in egg laying and incubation affected mortality risk, most relationships were not consistent with the cost of reproduction hypothesis; birds with extensive prior investments in egg production or incubation typically survived better, suggesting that variation in individual quality drove both relationships. We conclude that for breeding female Mallards, the primary cost of reproduction is a fixed cost associated with placing oneself at risk to predators while incubating nests in terrestrial habitats.

Accumulated metal speciation in earthworm populations with multi-generational exposure to metalliferous soils: cell fractionation and high energy synchrotron analyses

Predicting metal bioaccumulation and toxicity in soil organisms is complicated by site-specific biotic and abiotic parameters. In this study we exploited tissue fractionation and digestion techniques, combined with X-ray absorption spectroscopy (XAS), to investigate the whole-body and subcellular distributions, ligand affinities, and coordination chemistry of accumulated Pb and Zn in field populations of the epigeic earthworm Lumbricus rubellus inhabiting three contrasting metalliferous and two unpolluted soils. Our main findings were (i) earthworms were resident in soils with concentrations of Pb and Zn ranging from 1200 to 27 000 mg kg(-1) and 200 to 34 000 mg kg(-1), respectively; (ii) Pb and Zn primarily accumulated in the posterior alimentary canal in nonsoluble subcellular fractions of earthworms; (iii) site-specific differences in the tissue and subcellular partitioning profiles of populations were observed, with earthworms from a calcareous site partitioning proportionally more Pb to their anterior body segments and Zn to the chloragosome-rich subcellular fraction than their acidic-soil inhabiting counterparts; (iv) XAS indicated that the interpopulation differences in metal partitioning between organs were not accompanied by qualitative differences in ligand-binding speciation, because crystalline phosphate-containing pyromorphite was a predominant chemical species in the whole-worm tissues of all mine soil residents. Differences in metal (Pb, Zn) partitioning at both organ and cellular levels displayed by field populations with protracted histories of metal exposures may reflect their innate ecophysiological responses to essential edaphic variables, such as Ca2+ status. These observations are highly significant in the challenging exercise of interpreting holistic biomarker data delivered by "omic" technologies.

Evidence of heavy metal movement down the profile of a heavily-sludged soil

Two sites in central England where sewage sludge has been deposited for decades were studied to measure the heavy metal distribution in the soil profiles. The first site (S 1) was a field receiving heavy loads sludge from a nearby wastewater treatment plant, and the second (S2) was a farm applying 'normal' sludge rates of 8 t ha(-1) y(-1) of the same sludge. Soil samples were also taken by a near-by untreated control site. In S I the movement of heavy metals was significant even down to 80 cm depth compared to the control. In S2, the concentrations of lead (Pb) and zinc (Zn) and the organic matter content were higher than the control down to 20 cm, while nickel (Ni) moved significantly down to 80 cm. This underlies. the possibility that the metals bound onto organic surfaces moved along with organic matter down to that depth. The movement of metals in S2 points out the potential risks of applying sewage sludge for a long time.