806 research outputs found

    Dense active matter model of motion patterns in confluent cell monolayers

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    Epithelial cell monolayers show remarkable displacement and velocity correlations over distances of ten or more cell sizes that are reminiscent of supercooled liquids and active nematics. We show that many observed features can be described within the framework of dense active matter, and argue that persistent uncoordinated cell motility coupled to the collective elastic modes of the cell sheet is sufficient to produce swirl-like correlations. We obtain this result using both continuum active linear elasticity and a normal modes formalism, and validate analytical predictions with numerical simulations of two agent-based cell models, soft elastic particles and the self-propelled Voronoi model together with in-vitro experiments of confluent corneal epithelial cell sheets. Simulations and normal mode analysis perfectly match when tissue-level reorganisation occurs on times longer than the persistence time of cell motility. Our analytical model quantitatively matches measured velocity correlation functions over more than a decade with a single fitting parameter.Comment: updated version accepted for publication in Nat. Com

    DEDICATE: proposal for a conceptual framework to develop dementia-friendly Integrated eCare support

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    Background: Evidence shows that the implementation of Information and Communication Technologies (ICT) enabled services supporting integrated dementia care represents an opportunity that faces multi-pronged challenges. First, the provision of dementia support is fragmented and often inappropriate. Second, available ICT solutions in this field do not address the full spectrum of support needs arising across an individual’s whole dementia journey. Current solutions fail to harness the potential of available validated e-health services, such as telehealth and telecare, for the purposes of dementia care. Third, there is a lack of understanding of how viable business models in this field can operate. The field comprises both professional and non-professional players that interact and have roles to play in ensuring that useful technologies are developed, implemented and used. Methods: Starting from a literature review, including relevant pilot projects for ICT-based dementia care, we define the major requirements of a system able to overcome the limitations evidenced in the literature, and how this system should be integrated in the socio-technical ecosystem characterizing this disease. From here, we define the DEDICATE architecture of such a system, and the conceptual framework mapping the architecture over the requirements. Results: We identified three macro-requirements, namely the need to overcome: deficient technology innovation, deficient service process innovation, and deficient business models innovation. The proposed architecture is a three level architecture in which the center (data layer) includes patients’ and informal caregivers’ preferences, memories, and other personal data relevant to sustain the dementia journey, is connected through a middleware (service layer), which guarantees core IT services and integration, to dedicated applications (application layer) to sustain dementia care (Formal Support Services, FSS), and to existing formal care infrastructures, in order to guarantee care coordination (Care Coordination Services, CCS). Conclusions: The proposed DEDICATE architecture and framework envisages a feasible means to overcome the present barriers by: (1) developing and integrating technologies that can follow the patient and the caregivers throughout the development of the condition, since the early stages in which the patient is able to build up preferences and memories will be used in the later stages to maximise personalization and thereby improve efficacy and usability (technology innovation); (2) guaranteeing the care coordination between formal and informal caregivers, and giving an active yet supported role to the latter (service innovation); and (3) integrating existing infrastructures and care models to decrease the cost of the overall care pathway, by improving system interoperability (business model innovation)

    Chronification of migraine: what clinical strategies to combat it?

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    Once migraine becomes chronic and has transformed into a form of headache that occurs daily or almost, the treatment options available are few and complex. This makes it important to take action before this point is reached, using all the measures that can be obtained from our current knowledge of chronic migraine (or transformed migraine) on the one hand, and on the potential factors of chronification (or transformation) on the other. Therefore, in order to reduce the risk of migraine chronification, it would appear important to: (a) administer suitable preventive treatments for subjects who have been suffering from migraines 654 days a month for 653 months; (b) take special care not to overuse symptomatic medications, particularly when they contain substances with a sedative effect; and (c) investigate the concomitant presence of depression, hypertension and excess weight and administer appropriate treatment when presen

    San Francisco Hep B Free: A Grassroots Community Coalition to Prevent Hepatitis B and Liver Cancer

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    Chronic hepatitis B is the leading cause of liver cancer and the largest health disparity between Asian/Pacific Islanders (APIs) and the general US population. The Hep B Free model was launched to eliminate hepatitis B infection by increasing hepatitis B awareness, testing, vaccination, and treatment among APIs by building a broad, community-wide coalition. The San Francisco Hep B Free campaign is a diverse public/private collaboration unifying the API community, health care system, policy makers, businesses, and the general public in San Francisco, California. Mass-media and grassroots messaging raised citywide awareness of hepatitis B and promoted use of the existing health care system for hepatitis B screening and follow-up. Coalition partners reported semi-annually on activities, resources utilized, and system changes instituted. From 2007 to 2009, over 150 organizations contributed approximately $1,000,000 in resources to the San Francisco Hep B Free campaign. 40 educational events reached 1,100 healthcare providers, and 50% of primary care physicians pledged to screen APIs routinely for hepatitis B. Community events and fairs reached over 200,000 members of the general public. Of 3,315 API clients tested at stand-alone screening sites created by the campaign, 6.5% were found to be chronically infected and referred to follow-up care. A grassroots coalition that develops strong partnerships with diverse organizations can use existing resources to successfully increase public and healthcare provider awareness about hepatitis B among APIs, promote routine hepatitis B testing and vaccination as part of standard primary care, and ensure access to treatment for chronically infected individuals

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Characterization of Changes in Serum Anti-Glycan Antibodies in Crohn's Disease – a Longitudinal Analysis

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    INTRODUCTION: Anti-glycan antibodies are a promising tool for differential diagnosis and disease stratification of patients with Crohn's disease (CD). We longitudinally assessed level and status changes of anti-glycan antibodies over time in individual CD patients as well as determinants of this phenomenon. METHODS: 859 serum samples derived from a cohort of 253 inflammatory bowel disease (IBD) patients (207 CD, 46 ulcerative colitis (UC)) were tested for the presence of anti-laminarin (Anti-L), anti-chitin (Anti-C), anti-chitobioside (ACCA), anti-laminaribioside (ALCA), anti-mannobioside (AMCA) and anti-Saccharomyces cerevisiae (gASCA) antibodies by ELISA. All patients had at least two and up to eleven serum samples taken during the disease course. RESULTS: Median follow-up time for CD was 17.4 months (Interquartile range (IQR) 8.0, 31.6 months) and for UC 10.9 months (IQR 4.9, 21.0 months). In a subgroup of CD subjects marked changes in the overall immune response (quartile sum score) and levels of individual markers were observed over time. The marker status (positive versus negative) remained widely stable. Neither clinical phenotype nor NOD2 genotype was associated with the observed fluctuations. In a longitudinal analysis neither changes in disease activity nor CD behavior led to alterations in the levels of the glycan markers. The ability of the panel to discriminate CD from UC or its association with CD phenotypes remained stable during follow-up. In the serum of UC patients neither significant level nor status changes were observed. CONCLUSIONS: While the levels of anti-glycan antibodies fluctuate in a subgroup of CD patients the antibody status is widely stable over time

    Curcumin-induced HDAC inhibition and attenuation of medulloblastoma growth in vitro and in vivo

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    <p>Abstract</p> <p>Background</p> <p>Medulloblastoma is the most common brain tumor in children, and its prognosis is worse than for many other common pediatric cancers. Survivors undergoing treatment suffer from serious therapy-related side effects. Thus, it is imperative to identify safer, effective treatments for medulloblastoma. In this study we evaluated the anti-cancer potential of curcumin in medulloblastoma by testing its ability to induce apoptosis and inhibit tumor growth <it>in vitro </it>and <it>in vivo </it>using established medulloblastoma models.</p> <p>Methods</p> <p>Using cultured medulloblastoma cells, tumor xenografts, and the Smo/Smo transgenic medulloblastoma mouse model, the antitumor effects of curcumin were tested <it>in vitro </it>and <it>in vivo</it>.</p> <p>Results</p> <p>Curcumin induced apoptosis and cell cycle arrest at the G2/M phase in medulloblastoma cells. These effects were accompanied by reduced histone deacetylase (HDAC) 4 expression and activity and increased tubulin acetylation, ultimately leading to mitotic catastrophe. In <it>in vivo </it>medulloblastoma xenografts, curcumin reduced tumor growth and significantly increased survival in the Smo/Smo transgenic medulloblastoma mouse model.</p> <p>Conclusions</p> <p>The <it>in vitro </it>and <it>in vivo </it>data suggest that curcumin has the potential to be developed as a therapeutic agent for medulloblastoma.</p

    An analysis of waves underlying grid cell firing in the medial enthorinal cortex

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    Layer II stellate cells in the medial enthorinal cortex (MEC) express hyperpolarisation-activated cyclic-nucleotide-gated (HCN) channels that allow for rebound spiking via an I_h current in response to hyperpolarising synaptic input. A computational modelling study by Hasselmo [2013 Neuronal rebound spiking, resonance frequency and theta cycle skipping may contribute to grid cell firing in medial entorhinal cortex. Phil. Trans. R. Soc. B 369: 20120523] showed that an inhibitory network of such cells can support periodic travelling waves with a period that is controlled by the dynamics of the I_h current. Hasselmo has suggested that these waves can underlie the generation of grid cells, and that the known difference in I_h resonance frequency along the dorsal to ventral axis can explain the observed size and spacing between grid cell firing fields. Here we develop a biophysical spiking model within a framework that allows for analytical tractability. We combine the simplicity of integrate-and-fire neurons with a piecewise linear caricature of the gating dynamics for HCN channels to develop a spiking neural field model of MEC. Using techniques primarily drawn from the field of nonsmooth dynamical systems we show how to construct periodic travelling waves, and in particular the dispersion curve that determines how wave speed varies as a function of period. This exhibits a wide range of long wavelength solutions, reinforcing the idea that rebound spiking is a candidate mechanism for generating grid cell firing patterns. Importantly we develop a wave stability analysis to show how the maximum allowed period is controlled by the dynamical properties of the I_h current. Our theoretical work is validated by numerical simulations of the spiking model in both one and two dimensions
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