Exploring priming strategies to improve stress resilience of Posidonia oceanica seedlings.

Seagrasses' ability to store information after exposure to stress (i.e. stress memory) and to better respond to further stress (i.e. priming) have recently been observed, although the temporal persistence of the memory and the mechanisms for priming induction remain to be defined. Here, we explored three priming strategies in Posidonia oceanica seedlings, each inducing a different level of stress, for temperature and salinity. We investigated changes in morphometry, growth rate and biomass between primed and non-primed seedlings. The results showed similar behaviour of seedlings when exposed to an acute stress event, regardless of whether they had been primed or not and of the priming strategy received. This opens the debate on the level of stress necessary for inducing a priming status and the persistence of the stress memory in P. oceanica seedlings. Although no priming-induced stress resistance was observed, seedlings showed unexpectedly high resilience to extreme levels of both abiotic stressors.

Photo-acclimatory thresholds anticipate sudden shifts in seagrass ecosystem state under reduced light conditions.

Seagrass ecosystems usually respond in a nonlinear fashion to increasing pressures and environmental changes. Feedback mechanisms operating at the ecosystem level and involving multiple interactions among the seagrass meadow, its associated community and the physical environment are known to play a major role in such nonlinear responses. Phenotypic plasticity may also be important for buffering these ecological thresholds (i.e., regime shifts) as many physiological processes show nonlinear responses to gradual environmental changes, conferring the appearance of resistance before the effects at the organism and population levels are visible. However, the potential involvement of plant plasticity in driving catastrophic shifts in seagrass ecosystems has not yet been assessed. In this study, we conducted a manipulative 6-month light-gradient experiment in the field to capture nonlinearities of the physiological and population responses of the seagrass Cymodocea nodosa to gradual light reduction. The aim was to explore if and how the photo-acclimatory responses of shaded plants are translated to the population level and, hence, to the ecosystem level. Results showed that the seagrass population was rather stable under increasing shading levels through the activation of multilevel photo-acclimative responses, which are initiated with light reduction and modulated in proportion to shading intensity. The activation of photo-physiological and metabolic compensatory responses allowed shaded plants to sustain nearly constant plant productivity (metabolic carbon balance) along a range of shading levels before losing linearity and starting to decline. The species then activated plant- and meadow-scale photo-acclimative responses and drew on its energy reserves (rhizome carbohydrates) to confer additional population resilience. However, when the integration of all these buffering mechanisms failed to counterbalance the effects of extreme light limitation, the population collapsed, giving place to a phase shift from vegetated to bare sediments with catastrophic ecosystem outcomes. Our findings evidence that ecological thresholds in seagrass ecosystems under light limitation can be explained by the role of species' compensatory responses in modulating population-level responses. The thresholds of these plastic responses anticipate the sudden loss of seagrass meadows with the potential to be used as early warning indicators signalling the imminent collapse of the ecosystem, which is of great value for the real-world management of seagrass ecosystems.

A Preliminary Cost-Utility Analysis of the Prosthetic Care Innovations: Case of the Keep Walking Implant.

Several obstacles must be overcome before preliminary cost-utility analyses (CUA) of prosthetic care innovations can be routinely performed. The basic framework of preliminary CUAs and hands- on recommendations suggested previously might contribute to wider adoption. However, a practical application for an emerging intervention is needed to showcase the capacity of this proposed preliminary CUA framework. This study presented the outcomes of preliminary CUA of the distal weight bearing Keep Walking Implant (KWI), an emerging prosthetic care innovation that may reduce socket fittings for individuals with transfemoral amputation. The preliminary CUAs compared the provision of prosthetic care without (usual intervention) and with the KWI (new intervention) using a 15-step iterative process focused on feasibility, constructs, analysis, and interpretations of outcomes from an Australia government prosthetic care perspective over a six-year time horizon. Baseline and incremental costs were extracted from schedules of allowable expenses. Baseline utilities were extracted from a study and converted into quality-adjusted life-year (QALY). Incremental utilities were calculated based on sensible gains of QALY from baselines. The provision of the prosthetic care with the KWI could generate an indicative incremental cost-utility ratio (ICUR) of -$36,890 per QALY, which was $76,890 per QALY below willingness-to-pay threshold, provided that the KWI reduces costs by $17,910 while increasing utility by 0.485 QALY compared to usual interventions. This preliminary CUA provided administrators of healthcare organizations in Australia and elsewhere with prerequisite evidence justifying further access to market and clinical introduction of the KWI. Altogether, this work suggests that the basic framework of the preliminary CUA of a prosthetic care innovation proposed previously is feasible and informative when a series of assumptions are carefully considered. This study further confirms that preliminary CUAs prosthetic care interventions might be a relevant alternative to full CUA for other medical treatments.

Carbon economy of Mediterranean seagrasses in response to thermal stress.

Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebrates. To test this hypothesis, the carbon balance of Posidonia oceanica and Cymodocea nodosa plants from contrasting thermal environments was investigated during a simulated heatwave, by analyzing their photosynthetic performance, carbon balance (ratio photosynthesis:respiration), carbohydrates content, growth and mortality. Both species were able to overcome and recover from the thermal stress produced by the six-week exposure to temperatures 4 °C above mean summer levels, albeit plants from cold waters were more sensitive to warming than plants from warm waters as reflected by their inability to maintain their P:R ratio unaltered. The strategies through which plants tend to preserve their energetic status varied depending on the biology of the species and the thermal origin of plants. These included respiratory homeostasis (P. oceanica warm-plants), carbon diversion from growth to respiration (C. nodosa cold-plants) or storage (P. oceanica warm-plants) and changes in biomass allocation (C. nodosa warm-plants). Findings suggest an important geographic heterogeneity in the overall response of Mediterranean seagrasses to warming with potential negative impacts on the functions and services offered by seagrass meadows including among others their capacity for carbon sequestration and carbon export to adjacent ecosystems.

Experimental evidence of warming-induced flowering in the Mediterranean seagrass Posidonia oceanica.

Sexual reproduction in predominantly clonal marine plants increases recombination favoring adaptation and enhancing species resilience to environmental change. Recent studies of the seagrass Posidonia oceanica suggest that flowering intensity and frequency are correlated with warming events associated with global climate change, but these studies have been observational without direct experimental support. We used controlled experiments to test if warming can effectively trigger flowering in P. oceanica. A six-week heat wave was simulated under laboratory mesocosm conditions. Heating negatively impacted leaf growth rates, but by the end of the experiment most of the heated plants flowered, while controls plants did not. Heated and control plants were not genetically distinct and flowering intensity was significantly correlated with allelic richness and heterozygosity. This is an unprecedented finding, showing that the response of seagrasses to warming will be more plastic, more complex and potentially more resilient than previously imagined.

Antioxidant response to heat stress in seagrasses. A gene expression study.

Seawater warming associated to the ongoing climate change threatens functioning and survival of keystone coastal benthic species such as seagrasses. Under elevated temperatures, the production of reactive oxygen species (ROS) is increased and plants must activate their antioxidant defense mechanisms to protect themselves from oxidative damage. Here we explore from a molecular perspective the ability of Mediterranean seagrasses to activate heat stress response mechanisms, with particular focus on antioxidants. The level of expression of targeted genes was analyzed in shallow and deep plants of the species Posidonia oceanica and in shallow plants of Cymodocea nodosa along an acute heat exposure of several days and after recovery. The overall gene expression response of P. oceanica was more intense and complete than in C. nodosa and reflected a higher oxidative stress level during the experimental heat exposure. The strong activation of genes with chaperone activity (heat shock proteins and a luminal binding protein) just in P. oceanica plants, suggested the higher sensitivity of the species to increased temperatures. In spite of the interspecific differences, genes from the superoxide dismutase (SOD) family seem to play a pivotal role in the thermal stress response of Mediterranean seagrasses as previously reported for other marine plant species. Shallow and deep P. oceanica ecotypes showed a different timing of response to heat. Shallow plants early responded to heat and after a few days relaxed their response which suggests a successful early metabolic adjustment. The response of deep plants was delayed and their recovery incomplete evidencing a lower resilience to heat in respect to shallow ecotypes. Moreover, shallow ecotypes showed some degree of pre-adaptation to heat as most analyzed genes showed higher constitutive expression levels than in deep ecotypes. The recurrent exposure of shallow plants to elevated summer temperatures has likely endowed them with a higher basal level of antioxidant defense and a faster responsiveness to warming than deep plants. Our findings match with previous physiological studies and supported the idea that warming will differently impact Mediterranean seagrass meadows depending on the species as well as on the depth (i.e. thermal regimen) at which the meadow grows. The increase in the incidence of summer heat waves could therefore produce a significant change in the distribution and composition of Mediterranean seagrass meadows with considerable consequences for the functioning of the whole ecosystem and for the socio-economic services that these ecosystems offer to the riverine populations.

Osteointegración con el sistema Keep Walking Advanced® en una paciente amputada transfemoral / Osseointegration with the Keep Walking Advanced® system in a transfemoral patient

Aproximadamente una tercera parte de los pacientes con una amputación transfemoral van a padecer problemas crónicos relacionados con el encaje de su prótesis. El 72% de los pacientes amputados refieren sudoración o sensación de calor por culpa del encaje, el 62% reportan lesiones cutáneas o irritaciones de la piel del muñón, el 53% fatiga del muñón, el 51% dolor del muñón y el 38% acaban abandonando el uso de la prótesis. La osteointegración es una técnica que evita estos problemas generados en la piel del paciente, ya que permite un anclaje directo de la prótesis al implante intramedular colocado en el fémur del paciente. Presentamos el caso de una paciente amputada transfemoral de 38 años tratada mediante una cirugía de osteointegración con el implante Keep Walking Advanced® para mejorar el uso de la prótesis sin la necesidad de encaje (AU)

Approximately one third of patients with a transfemoral amputation will have chronic problems related to the fitting of the prosthesis. More than two thirds (72%) of amputees report sweating or feeling hot because of the socket, 62% report skin lesions or skin irritation of the stump, 53% stump fatigue, 51% stump pain and 38% do not use the prosthesis. Osseointegration is a technique that avoids these problems in the patient's skin, allowing direct anchoring of the prosthesis to the intramedullary implant placed in the patient's femur. We report the case of a 38-year-old transfemoral amputee who underwent implantation of the Keep Walking Advanced® implant to improve the use of the prosthesis without the need for socket fitting (AU)

Combined in situ effects of metals and nutrients on marine biofilms: Shifts in the diatom assemblage structure and biological traits.

The effects of multiple stressors on marine diatom assemblages are still poorly understood. The interactive effects of metals and nutrients were assessed in two coastal biofilms grown at a reference site and a historically contaminated site. The biofilms were exposed in situ to pulse exposures of metals (Zn and Pb) and nutrients (N and P) individually and in combination to mimic patterns of discharge in the study area. The reference community's structure (composition and abundance of taxa) was modified after metals and/or nutrients exposure, but each stressor acted in different way. Irrespective of the stressors or scenario, the abundance of the dominant species Opephora krumbeinii declined, and it is proposed as sensitive species. Nutrient supply favoured the proliferation of certain species with high nutrient tolerances (Fragilaria famelica, Tabularia ktenoeides), whereas metals promoted the colonisation of metal-tolerant species, e.g., Berkeleya fennica, Opephora marina. Simultaneous exposure induced an amplification of levels of accumulated metals, chlorophyll a and EPS contents and triggered the succession of species towards tolerant species with specific growth. Metals seemed to act as a selective factor of metal-tolerant species, and nutrients favoured the proliferation of those species forming zig-zag colonies (Neosynedra provincialis), mucous tubes (Berkeleya spp.) and motile diatoms (Navicula salinicola, Nitzschia incognita), resulting in biofilms with a more complex architecture. The diatom communities from the historically contaminated site were more resistant to pulse exposure, but metals or nutrients loads induced overproduction of mucilage. We propose that growth forms may complement taxonomic approaches and provide a quick and easy way to detect community changes related to metal and nutrient pollution.

Assessment of the abiotic and biotic effects of sodium metabisulphite pulses discharged from desalination plant chemical treatments on seagrass (Cymodocea nodosa) habitats in the Canary Islands.

Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatments with sodium metabisulphite, which have potentially toxic effects to the environment for marine life, although no empirical and experimental evidence for this is yet available. The aim of this study was to characterise for the first time, the physico-chemical modification of the marine environment and its biological effects, caused by hypersaline plumes during these membrane cleaning treatments. The case study was the Maspalomas II desalination plant, located in the south of Gran Canaria (Canary Islands, Spain). Toxicity bioassays were performed on marine species characteristic for the infralittoral soft bottoms influenced by the brine plume (Synodus synodus and Cymodocea nodosa), and revealed a high sensitivity to short-term exposure to low sodium metabisulphite concentrations. The corrective measure of incorporating a diffusion system with Venturi Eductors reduced nearly all the areas of influence, virtually eliminating the impact of the disinfectant.

Valoración de la movilidad en pacientes con amputación de miembro inferior / Evaluation of mobility in patients with a lower limb amputation

Objetivo. El objetivo principal es revisar las herramientas disponibles para valorar la movilidad del paciente amputado de miembro inferior con el fin de identificar las más útiles en cuanto a información clínica, sencillez técnica y tiempo de realización para poder aplicarlas en la práctica clínica diaria. Los individuos que sufren una amputación de miembro inferior presentan un deterioro funcional que afecta a múltiples facetas de la vida, como la movilidad. La movilidad es una necesidad básica física, vital y social y su recuperación óptima es uno de los principales objetivos de los programas de rehabilitación del paciente amputado. Método. Se realizó una búsqueda sistemática de los estudios relevantes publicados desde enero de 2003 hasta enero de 2010 en MEDLINE, EMBASE, Cochrane Database y PEDro, incluyendo ensayos clínicos aleatorizados, metaanálisis, revisiones sistemáticas y artículos de revisión; también se revisaron diversas guías de práctica clínica. Resultados y conclusiones. A pesar de encontrar referencias de múltiples escalas genéricas, específicas, cuestionarios y tests de ejecución, no se encuentra en la literatura evidencia de consenso respecto a cuáles son las herramientas más adecuadas para valorar la movilidad del paciente amputado de extremidad inferior. Los tests de marcha se han demostrado fiables y sensibles a los cambios producidos por la rehabilitación, y su resultado se correlaciona con medidas de función física y con el uso de la prótesis, son prácticos y simples, por lo que pueden ser incluidos en la práctica clínica habitual, dejando los cuestionarios y tests específicos para el ámbito de la investigación(AU)

Objective. The principal objective was to review the available tools to measure mobility in lower limb amputees and to identify the most useful tools in terms of clinical information, technical simplicity and time to performance so that it can be used in the daily clinical practice. Individuals who have suffered a lower limb amputation have a functional deterioration that affects many aspects of life, including mobility. Mobility is a basic physical, vital and social need and its optimal recovery is one of the main objectives of the Rehabilitation programs for amputee patients. Methods. We conducted a systematic search for relevant studies published from January 2003 to January 2010 in MEDLINE, EMBASE, Cochrane and PEDro Database, including randomized clinical trials, review articles, systematic reviews and meta-analysis. Several clinical practice guidelines were also reviewed. Results and conclusions. Despite finding references of many generic scales, specific questionnaires and performance tests, no evidence of consensus was found in literature for the most appropriate tools to assess lower limb amputee's mobility. The Walking Tests have been found to be reliable and sensitive to changes related to the rehabilitation treatment and their outcomes are correlated with measures of physical function and the use of the prosthesis. They are practical and easy-to-use tests so that they can be included in the routine clinical practice, reserving the questionnaires and specific tests for research(AU)