581 research outputs found

    The Plight of the Lucluc: Examining the Deadly Mystery of Nodding Syndrome

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    Nodding syndrome (NS) is an emerging epidemic neurological disease that is shrouded in mystery. It is currently only found in the post-conflict regions of South Sudan, northern Uganda, and Tanzania. NS occurs in children from the ages of five to fifteen and is characterized by a loss of motor control in the neck muscles. Seizure episodes can range in intensity from atonic to tonic-clonic, and the onset of the first episode generally marks the beginning of a decline in the child’s physical and mental health. NS is a progressive disease that generally results in physical wasting, stunted growth, behavioral difficulties, and a decline in cognitive and motor skills. The underlying cause of the disease has yet to be soundly established, but several closely correlated factors have been discovered and effective treatment methods are currently being developed. Children with NS are also susceptible to detrimental social factors such as negative perception and stigmatization. Additionally, socioeconomic conditions greatly influence the ability of healthcare workers to identify and treat the disease

    The Effects of a Prescribed Burn on Streambed Sediments, Macroinvertebrate Assemblages, and Water Quality in the Valle Toledo, Valles Caldera National Preserve, New Mexico

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    Lotic ecosystems of the southwestern U.S. can be severely affected by wildfires causing alterations in water chemistry, sedimentation from runoff events, and changes in macro invertebrate community structure. In these same systems, the use of prescribed burns as forest and/or grassland management tools also may cause changes. The severity of these changes in comparison to wildfires is of primary importance to the effectiveness of these management tools, as any degradation of aquatic habitats is of serious concern in a semi-arid region. This study evaluates the effects of a recent prescribed burn in the Valle Toledo section of the Valles Caldera National Preserve, November 2005. Factors affecting the outcome of the burn, including a marked lack of winter precipitation, are discussed and data are presented on changes in water chemistry, sedimentation, and macro invertebrate assemblages, or the lack thereof, from pre-burn to post-burn and post-snowmelt conditions. Results of the study show no major overall degradation of the aquatic habitats in this area, although some localized changes did occur. Elevation of stream nitrate/nitrite concentrations were observed in the burn stream immediately post-burn, which did not decline until late spring. Carbon/nitrogen analysis of stream sediments revealed a localized effect of C:N ratio increase at snowmelt at two of the burn sampling sites. Macroinvertebrate assemblages were mostly unaltered immediately after the burn, though some decline in taxa richness and Jaccard\u27s similarity within the burn stream were observed at snowmelt. Continued monitoring will be needed to determine if these effects are mitigated and how quickly

    Validation and reproducibility of computerised cell-viability analysis of tissue slices

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    BACKGROUND: The identification of live cells using membrane integrity dyes has become a frequently used technique, especially with articular cartilage and chondrocytes in situ where tissue slices are used to assess cell recovery as a function of location. The development of a reproducible computerised method of cell evaluation would eliminate many variables associated with manual counting and significantly reduce the amount of time required to evaluate experimental results. METHODS: To validate a custom computerised counting program, intra-person and inter-person cell counts of nine human evaluators (three groups – unskilled, novice, and experienced) were compared with repeated pixel counts of the custom program on 15 digitised images (in triplicate) of chondrocytes in situ stained with fluorescent dyes. RESULTS: Results indicated increased reproducibility with increased experience within evaluators [Intraclass Correlation Coefficient (ICC) range = 0.67 (unskilled) to 0.99 (experienced)] and between evaluators [ICC = 0.47 (unskilled), 0.85 (novice), 0.93 (experienced)]. The computer program had perfect reproducibility (ICC = 1.0). There was a significant relationship between the average of the experienced evaluators results and the custom program results (ICC = 0.77). CONCLUSIONS: This study demonstrated that increased experience in cell counting resulted in increased reproducibility both within and between human evaluators but confirmed that the computer program was the most reproducible. There was a good correlation between the intact cell recovery determined by the computer program and the experienced human evaluators. The results of this study showed that the computer counting program was a reproducible tool to evaluate intact cell recovery after use of membrane integrity dyes on chondrocytes in situ. This and the significant decrease in the time used to count the cells by the computer program advocate its use in future studies because it has significant advantages

    Ectopic models for endochondral ossification: comparing pellet and alginate bead culture methods

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    Key aspects of native endochondral bone development and fracture healing can be mimicked in mesenchymal stem cells (MSCs) through standard in vitro chondrogenic induction. Exploiting this phenomenon has recently emerged as an attractive technique to engineer bone tissue, however, relatively little is known about the best conditions for doing so. The objective of the present study was to compare the bone-forming capacity and angiogenic induction of hypertrophic cell constructs containing human adipose-derived stem cells (hASCs) primed for chondrogenesis in two different culture systems: high-density pellets and alginate bead hydrogels. The hASC constructs were subjected to 4 weeks of identical chondrogenic induction in vitro, encapsulated in an agarose carrier, and then implanted subcutaneously in immune-compromised mice for 8 weeks to evaluate their endochondral potential. At the time of implantation, both pellets and beads expressed aggrecan and type II collagen, as well as alkaline phosphatase (ALP) and type X collagen. Interestingly, ASCs in pellets formed a matrix containing higher glycosaminoglycan and collagen contents than that in beads, and ALP activity per cell was higher in pellets. However, after 8 weeks in vivo, pellets and beads induced an equivalent volume of mineralized tissue and a comparable level of vascularization. Although osteocalcin and osteopontin-positive osteogenic tissue and new vascular growth was found within both types of constructs, all appeared to be better distributed throughout the hydrogel beads. The results of this ectopic model indicate that hydrogel culture may be an attractive alternative to cell pellets for bone tissue engineering via the endochondral pathway

    Cryoprotectant kinetic analysis of a human articular cartilage vitrification protocol

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    AbstractWe recently published a protocol to vitrify human articular cartilage and a method of cryoprotectant removal in preparation for transplantation. The current study’s goal was to perform a cryoprotectant kinetic analysis and theoretically shorten the procedure used to vitrify human articular cartilage. First, the loading of the cryoprotectants was modeled using Fick’s law of diffusion, and this information was used to predict the kinetics of cryoprotectant efflux after the cartilage sample had been warmed. We hypothesized that diffusion coefficients obtained from the permeation of individual cryoprotectants into porcine articular cartilage could be used to provide a reasonable prediction of the cryoprotectant loading and of the combined cryoprotectant efflux from vitrified human articular cartilage. We tested this hypothesis with experimental efflux measurements. Osteochondral dowels from three patients were vitrified, and after warming, the articular cartilage was immersed in 3 mL X-VIVO at 4 °C in two consecutive solutions, each for 24 h, with the solution osmolality recorded at various times. Measured equilibrium values agreed with theoretical values within a maximum of 15% for all three samples. The results showed that diffusion coefficients for individual cryoprotectants determined from experiments with 2-mm thick porcine cartilage can be used to approximate the rate of efflux of the combined cryoprotectants from vitrified human articular cartilage of similar thickness. Finally, Fick’s law of diffusion was used in a computational optimization to shorten the protocol with the constraint of maintaining the theoretical minimum cryoprotectant concentration needed to achieve vitrification. The learning provided by this study will enable future improvements in tissue vitrification

    Contemporary medical television and crisis in the NHS

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    This article maps the terrain of contemporary UK medical television, paying particular attention to Call the Midwife as its centrepiece, and situating it in contextual relation to the current crisis in the NHS. It provides a historical overview of UK and US medical television, illustrating how medical television today has been shaped by noteworthy antecedents. It argues that crisis rhetoric surrounding healthcare leading up to the passing of the Health and Social Care Act 2012 has been accompanied by a renaissance in medical television. And that issues, strands and clusters have emerged in forms, registers and modes with noticeable regularity, especially around the value of affective labour, the cultural politics of nostalgia and the neoliberalisation of healthcare

    Using knowledge: the dilemmas of 'bridging research and policy'

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    The 'knowledge agenda' has become a central part of development discourse. This paper addresses one aspect of this discourse - the use of policy research in the social sciences - and the dilemmas that have been encountered by both development agencies and researchers in communicating and making use of that research. Development agencies as well as NGOs have initiated work to evaluate and document the effectiveness of research partnerships, knowledge capacity building and (social) science policy impact. As a multilateral initiative, the Global Development Network (GDN), and especially its 'Bridging Research and Policy' project, provides a vehicle to address issues related to research impact. Twelve perspectives on improving research and policy linkages are outlined to reveal that how the problem is defined shapes policy responses. Taken together, these explanations provide a multifaceted picture of the research-policy nexus indicating that there are many possible routes to 'bridging' research and policy. These diverse perspectives will be categorised into three broad categories of explanation: (i) supply-side; (ii) demand-led; and (iii) policy currents. However, knowledge is part of the solution to many development problems but not of itself a panacea

    No Pixel Left Behind: Interactively Visualizing ''Everything'' from NASA's Earth Observations

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    The problem: satellite swath overlaps. Polar orbiting satellites like Terra, Aqua, and the joint NASA/NOAA Suomi-NPP satellite circle the globe from pole to pole, collecting data daily, swath by swath. Having this density of data is great for building a comprehensive mosaic of the planet, but sometimes there is something interesting occurring in one swath but is covered by a subsequent swath when the satellite passes over 90 minutes later. With our new prototype based on Worldview and the Global Imagery Browse Services (GIBS), we combine the best of both worlds to interactively visualize the entire globe as a mosaic and allow the user to _peel away the overlaps_ to see every pixel that was observed by the satellite. This ability to look at every pixel - and to know when they were captured - is especially important near the poles where swath overlaps are most common

    Rapid automatic segmentation of abnormal tissue in late gadolinium enhancement cardiovascular magnetic resonance images for improved management of long-standing persistent atrial fibrillation

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    Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In order for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to ameliorate the AF management, the ready availability of the accurate enhancement segmentation is required. However, the computer-aided segmentation of enhancement in LGE CMR of AF is still an open question. Additionally, the number of centres that have reported successful application of LGE CMR to guide clinical AF strategies remains low, while the debate on LGE CMR’s diagnostic ability for AF still holds. The aim of this study is to propose a method that reliably distinguishes enhanced (abnormal) from non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and 3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients studied at our centre. Methods: Enhancement segmentation was achieved by employing thresholds benchmarked against the statistics of the whole left atrial blood-pool (LABP). The test-set cross-validation mechanism was applied to determine the input feature representation and algorithm that best predict enhancement threshold levels. Results: Global normalized intensity threshold levels T PRE = 1 1/4 and T POST = 1 5/8 were found to segment enhancement in data-sets acquired pre-ablation and at 3 months post-ablation, respectively. The segmentation results were corroborated by using visual inspection of LGE CMR brightness levels and one endocardial bipolar voltage map. The measured extent of pre-ablation fibrosis fell within the normal range for the specific arrhythmia phenotype. 3D volume renderings of segmented post-ablation enhancement emulated the expected ablation lesion patterns. By comparing our technique with other related approaches that proposed different threshold levels (although they also relied on reference regions from within the LABP) for segmenting enhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels employed by other centres may not be usable for clinical studies performed in our centre. Conclusions: The proposed technique has great potential for successful employment in the AF management within our centre. It provides a highly desirable validation of the LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition protocol and image analysis strategy inevitably impede the selection of a universally optimal algorithm for segmentation of enhancement in AF studies
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