605 research outputs found

    Measurement of species flux from a bubble using an acousto-electrochemical technique

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    An acousto-electrochemical technique is presented which, for the first time, offers the potential for measuring the flux of dissolved species in a liquid resulting from bubbles of a specific chosen size in the population. Laboratory trials are presented, but the device itself was damaged in the surf zone and no data was obtained from the ocean deployment. Nevertheless, the preceding laboratory tests demonstrate the viability of the technique. The device responds to perturbations of the fluid around a small electrode. Three such sources of motion must be characterised if it is to achieve the objective stated above. First, the perturbations resulting form the translatory motions of bubbles in the liquid. To obtain bubble radius resolution in the measurement of mass flux, however, it is necessary to apply to driving (‘pump’) sound field. Bubbles close to resonance will, in addition to a translatory motion, impart to the liquid a component of mass flux at the pump frequency. This is detected. However to show that this is the result of bubble wall pulsation, and not someother coupling, the amplitude of the pump field is increased until the electrochemical sensor detects Faraday waves on the bubble wall. Not only does this prove the relation between mass flux to bubble wall motion, it provides a second route by which the radius-resolved component of mass flux might be identified. In these preliminary laboratory tests, electrochemical detection of these motions was achieved through the observation of current produced by the reduction of a suitable redox agent present within the liquid phase of the solution employed. Preparations were made to obtain preliminary data from the Hurst Spit 2000 surf zone trial, but the device was damaged by the environment

    Expression microdissection isolation of enriched cell populations from archival brain tissue

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    BACKGROUND: Laser capture microdissection (LCM) is an established technique for the procurement of enriched cell populations that can undergo further downstream analysis, although it does have limitations. Expression microdissection (xMD) is a new technique that begins to address these pitfalls, such as operator dependence and contamination. NEW METHOD: xMD utilises immunohistochemistry in conjunction with a chromogen to isolate specific cell types by extending the fundamental principles of LCM to create an operator-independent method for the procurement of specific CNS cell types. RESULTS: We report how xMD enables the isolation of specific cell populations, namely neurones and astrocytes, from rat formalin fixed-paraffin embedded (FFPE) tissue. Subsequent reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirms the enrichment of these specific populations. RIN values after xMD indicate samples are sufficient to carry out further analysis. COMPARISON WITH EXISTING METHOD: xMD offers a rapid method of isolating specific CNS cell types without the need for identification by an operator, reducing the amount of unintentional contamination caused by operator error, whilst also significantly reducing the time required by the current basic LCM technique. CONCLUSIONS: xMD is a superior method for the procurement of enriched cell populations from post-mortem tissue, which can be utilised to create transcriptome profiles, aiding our understanding of the contribution of these cells to a range of neurological diseases. xMD also addresses the issues associated with LCM, such as reliance on an operator to identify target cells, which can cause contamination, as well as addressing the time consuming nature of LCM

    Electrospun Fibrinogen-Polydioxanone Composite Matrix: Potential for In Situ Urologic Tissue Engineering

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    Our objective is to demonstrate an electrospun fibrinogen-PDO (polydioxanone) composite scaffold will retain the superior cellular interaction of fibrinogen while producing a product with the functional strength needed for direct implantation. Fibrinogen-PDO composite scaffolds were electrospun with PDO ratios of 0% (pure fibrinogen), 10%, 20%, 30%, 40%, 50% and 100% (pure PDO) and disinfected using standard methods. Scaffolds were seeded with human BSM (bladder smooth muscle cells) and incubated with twice weekly media changes. Samples were removed at 7, 14 and 21 days for evaluation by collagen assay, scanning electron microscopy and histology. Cell seeding and culture demonstrated human BSM readily migrate throughout and remodel electrospun fibrinogen-PDO composite scaffolds with deposition of native collagen. Cell migration and collagen deposition increased with increasing fibrinogen concentration while scaffold integrity increased with increasing PDO concentration. Electrospun fibrinogen-PDO composite structures promote rapid cellular in-growth by human BSM while maintaining structural integrity. The fibrinogen to PDO ratio can be adjusted to achieve the desired properties required for a specific tissue engineering application. Our ultimate objective is to utilize this innovative biomaterial technology to produce an acellular, bioresorbable product that enables in situ tissue regeneration. While there is still much work to be done, these initial findings indicate fibrinogen-PDO composite scaffolds deserve further investigation

    The transfusion threshold for upper gastrointestinal bleeding is a hemoglobin of 7.0 g/dl or less

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    A critical appraisal and clinical application of Villanueva C, Colomo A, Bosch A, Concepcion M, Hernandez-Gea V, Aracil C. Transfusion strategies for acute upper gastrointestinal bleeding. New Eng J Med. 2013;368(1):11-21. doi: 10.1056/NEJMoa121180

    [Epidemiology of oral cavity cancers in France].

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    INTRODUCTION: We had for objective to describe the updated epidemiology of oral cancers in France. MATERIAL AND METHODS: Estimates made from data collected from various French cancer institutions. The distribution by topography, histology, regions, mean age, and specific incidence rates were calculated from the collected data. The survival data was taken from the Francim network studies. RESULTS: Approximately 7000 oral cavity cancers were diagnosed in France in 2005. In 2007, 1746 people died of that cancer. Standardized (world population) incidence rates are respectively, in men and women, 12.3 and 3.0 cases per 100,000 person-years. These cancers have significantly decreased in men: the standardized incidence rate decreased by 43.2% between 1980 and 2005. Among women, the trend is reversed with an increased incidence of 51.7% over the same period. CONCLUSION: In France, the incidence of oral cavity cancers has been strongly decreasing in men and strongly increasing in women. This trend should be compared to the frequency of the main risk factors: alcohol and tobacco

    Assessment of pollen rewards by foraging bees

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The removal of pollen by flower-visiting insects is costly to plants, not only in terms of production, but also via lost reproductive potential. Modern angiosperms have evolved various reward strategies to limit these costs, yet many plant species still offer pollen as a sole or major reward for pollinating insects. 2. The benefits plants gain by offering pollen as a reward for pollinating are defined by the behaviour of their pollinators, some of which feed on the pollen at the flower, while others collect pollen to provision offspring. 3. We explore how pollen impacts on the behaviour and foraging decisions of pollen-collecting bees, drawing comparisons with what is known for nectar rewards. This question is of particular interest since foraging bees typically do not ingest pollen during collection, meaning the sensory pathways involved in evaluating this resource are not immediately obvious. 4. Previous research focussed on whether foraging bees can determine the quality of pollen sources offered by different plant species, and attempted to infer the mechanisms underpinning such evaluations, mainly through observations of collection preferences in the field 5. More recent experimental research has started to focus on if pollen itself can mediate the detection of, and learning about, pollen sources and associated floral cues. 6. We review advancements in the understanding of how bees forage for pollen and respond to variation in pollen quality, and discuss future directions for studying how this ancestral floral food reward shapes the behaviour of pollinating insects
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