303 research outputs found

    An objective method to associate local weather extremes with characteristic circulation structures

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    In this paper we give methods to find characteristic circulation patterns which are connected to local extreme temperature anomalies. Two data reduction techniques are applied: Legendre polynomial fitting and watershedding. For polynomial fitting a clear trend is found with respect to local temperatures. However, the trend is not distinctive enough to give clear answers on the type of circulation patterns belonging to local extremes. The main advantage of watershedding is that the physical properties of the circulation patterns are retained while the dimension of the data is largely reduced. Expert knowledge, however, is needed to model these main features as predictors

    Use of virtual reality-based training in different fields of rehabilitation: A systematic review and meta-analysis

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    Objectives: To analyse the effectiveness of virtual reality-based interventions within several fields of rehabilitation, and to investigate whether the outcomes of virtual realitybased interventions, in terms of upper or lower limb function, gait and balance, differ with respect to the virtual reality system used. Methods: A search of PubMed database resulted in an initial total of 481 records. Of these, 27 articles were included in the study. A final total of 20 articles, with neurological, orthoapedic, geriatric or paediatric patients, published between 2012 and 2019, were included in the study. Two independent reviewers selected potentially relevant articles based on the inclusion criteria for fulltext reading. They extracted data, and evaluated the methodological quality of each study. Results: Seventeen studies were included in the metaanalysis. Eight studies analysed upper limb function, with no significant evidence that specialized VR is superior to conventional treatment. Regarding Fugl-Meyer scale results, the effect of specialized virtual reality therapy was found to be significantly better than conventional treatment. No significant differences between specialized VR and conventional treatment were observed in effects on hand dexterity and gait. There was a significant difference in effects on balance in favour of specialized virtual reality as compared to conventional treatment. Gaming virtual reality was significantly better than conventional treatment for upper limb function, but not for hand dexterity, gait and balance. Conclusion: Use of specialized virtual reality and gaming virtual reality can be advantageous for treatment of the upper extremity, but not for hand dexterity and gait in all pathologies considered. Specialized virtual reality can improve balance in neurological patients

    Gluon scattering in N=4{\cal N}=4 Super Yang-Mills at finite temperature

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    We extend the AdS/CFT prescription of Alday and Maldacena to finite temperature TT, defining the amplitude for gluon scattering in N=4{\cal N}=4 Super Yang-Mills at strong coupling from string theory. It is defined by a lightlike ''Wilson loop'' living at the horizon of the T-dual to the black hole in AdS space. Unlike the zero temperature case, this is different from the Wilson loop contour defined at the boundary of the AdS black hole metric, thus at finite TT there is no relation between gluon scattering amplitudes and the Wilson loop. We calculate the amplitude at strong coupling for forward scattering of a low energy gluon (E<TE<T) off a high energy gluon (ETE\gg T) in both cut-off and generalized dimensional regularization. The generalized dimensional regularization is defined in string theory as an IR modified dimensional reduction. For this calculation, the corresponding usual Wilson loop is related to the jet quenching parameter of the finite temperature N=4{\cal N}=4 SYM plasma, while the gluon scattering amplitude is related to the viscosity coefficient.Comment: 33 pages, 9 figures; clarifications of some points added, reference adde

    Co-localization and regulation of basic fibroblast growth factor and arginine vasopressin in neuroendocrine cells of the rat and human brain

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    <p>Abstract</p> <p>Background</p> <p>Adult rat hypothalamo-pituitary axis and choroid plexus are rich in basic fibroblast growth factor (FGF2) which likely has a role in fluid homeostasis. Towards this end, we characterized the distribution and modulation of FGF2 in the human and rat central nervous system. To ascertain a functional link between arginine vasopressin (AVP) and FGF2, a rat model of chronic dehydration was used to test the hypothesis that FGF2 expression, like that of AVP, is altered by perturbed fluid balance.</p> <p>Methods</p> <p>Immunohistochemistry and confocal microscopy were used to examine the distribution of FGF2 and AVP neuropeptides in the normal human brain. In order to assess effects of chronic dehydration, Sprague-Dawley rats were water deprived for 3 days. AVP neuropeptide expression and changes in FGF2 distribution in the brain, neural lobe of the pituitary and kidney were assessed by immunohistochemistry, and western blotting (FGF2 isoforms).</p> <p>Results</p> <p>In human hypothalamus, FGF2 and AVP were co-localized in the cytoplasm of supraoptic and paraventricular magnocellular neurons and axonal processes. Immunoreactive FGF2 was associated with small granular structures distributed throughout neuronal cytoplasm. Neurohypophysial FGF2 immunostaining was found in axonal processes, pituicytes and Herring bodies. Following chronic dehydration in rats, there was substantially-enhanced FGF2 staining in basement membranes underlying blood vessels, pituicytes and other glia. This accompanied remodeling of extracellular matrix. Western blot data revealed that dehydration increased expression of the hypothalamic FGF2 isoforms of ca. 18, 23 and 24 kDa. In lateral ventricle choroid plexus of dehydrated rats, FGF2 expression was augmented in the epithelium (Ab773 as immunomarker) but reduced interstitially (Ab106 immunostaining).</p> <p>Conclusions</p> <p>Dehydration altered FGF2 expression patterns in AVP-containing magnocellular neurons and neurohypophysis, as well as in choroid plexus epithelium. This supports the involvement of centrally-synthesized FGF2, putatively coupled to that of AVP, in homeostatic mechanisms that regulate fluid balance.</p

    Genetic drivers of kidney defects in the digeorge syndrome

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    BACKGROUND The DiGeorge syndrome, the most common of the microdeletion syndromes, affects multiple organs, including the heart, the nervous system, and the kidney. It is caused by deletions on chromosome 22q11.2; the genetic driver of the kidney defects is unknown. METHODS We conducted a genomewide search for structural variants in two cohorts: 2080 patients with congenital kidney and urinary tract anomalies and 22,094 controls. We performed exome and targeted resequencing in samples obtained from 586 additional patients with congenital kidney anomalies. We also carried out functional studies using zebrafish and mice. RESULTS We identified heterozygous deletions of 22q11.2 in 1.1% of the patients with congenital kidney anomalies and in 0.01% of population controls (odds ratio, 81.5; P = 4.5×1014). We localized the main drivers of renal disease in the DiGeorge syndrome to a 370-kb region containing nine genes. In zebrafish embryos, an induced loss of function in snap29, aifm3, and crkl resulted in renal defects; the loss of crkl alone was sufficient to induce defects. Five of 586 patients with congenital urinary anomalies had newly identified, heterozygous protein-Altering variants, including a premature termination codon, in CRKL. The inactivation of Crkl in the mouse model induced developmental defects similar to those observed in patients with congenital urinary anomalies. CONCLUSIONS We identified a recurrent 370-kb deletion at the 22q11.2 locus as a driver of kidney defects in the DiGeorge syndrome and in sporadic congenital kidney and urinary tract anomalies. Of the nine genes at this locus, SNAP29, AIFM3, and CRKL appear to be critical to the phenotype, with haploinsufficiency of CRKL emerging as the main genetic driver

    A systematic review of clinical trials of pharmacological interventions for acute ischaemic stroke (1955-2008) that were completed, but not published in full

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    <p>Abstract</p> <p>Background</p> <p>We assessed the prevalence, and potential impact of, trials of pharmacological agents for acute stroke that were completed but not published in full. Failure to publish trial data is to be deprecated as it sets aside the altruism of participants' consent to be exposed to the risks of experimental interventions, potentially biases the assessment of the effects of therapies, and may lead to premature discontinuation of research into promising treatments.</p> <p>Methods</p> <p>We searched the Cochrane Stroke Group's Specialised Register of Trials in June 2008 for completed trials of pharmacological interventions for acute ischaemic stroke, and searched MEDLINE and EMBASE (January 2007 - March 2009) for references to recent full publications. We assessed trial completion status from trial reports, online trials registers and correspondence with experts.</p> <p>Results</p> <p>We identified 940 trials. Of these, 125 (19.6%, 95% confidence interval 16.5-22.6) were completed but not published in full by the point prevalence date. They included 16,058 participants (16 trials had over 300 participants each) and tested 89 different interventions. Twenty-two trials with a total of 4,251 participants reported the number of deaths. In these trials, 636/4251 (15.0%) died.</p> <p>Conclusions</p> <p>Our data suggest that, at the point prevalence date, a substantial body of evidence that was of relevance both to clinical practice in acute stroke and future research in the field was not published in full. Over 16,000 patients had given informed consent and were exposed to the risks of therapy. Responsibility for non-publication lies with investigators, but pharmaceutical companies, research ethics committees, journals and governments can all encourage the timely publication of trial data.</p

    2-Hydroxylethyl methacrylate (HEMA), a tooth restoration component, exerts its genotoxic effects in human gingival fibroblasts trough methacrylic acid, an immediate product of its degradation

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    HEMA (2-hydroxyethyl methacrylate), a methacrylate commonly used in dentistry, was reported to induce genotoxic effects, but their mechanism is not fully understood. HEMA may be degraded by the oral cavity esterases or through mechanical stress following the chewing process. Methacrylic acid (MAA) is the primary product of HEMA degradation. In the present work we compared cytotoxic and genotoxic effects induced by HEMA and MAA in human gingival fibroblasts (HGFs). A 6-h exposure to HEMA or MAA induced a weak decrease in the viability of HGFs. Neither HEMA nor MAA induced strand breaks in the isolated plasmid DNA, but both compounds evoked DNA damage in HGFs, as evaluated by the alkaline comet assay. Oxidative modifications to the DNA bases were monitored by the DNA repair enzymes Endo III and Fpg. DNA damage induced by HEMA and MAA was not persistent and was removed during a 120 min repair incubation. Results from the neutral comet assay indicated that both compounds induced DNA double strand breaks (DSBs) and they were confirmed by the γ-H2AX assay. Both compounds induced apoptosis and perturbed the cell cycle. Therefore, methacrylic acid, a product of HEMA degradation, may be involved in its cytotoxic and genotoxic action

    Hemodialysis Removes Uremic Toxins That Alter the Biological Actions of Endothelial Cells

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    Chronic kidney disease is linked to systemic inflammation and to an increased risk of ischemic heart disease and atherosclerosis. Endothelial dysfunction associates with hypertension and vascular disease in the presence of chronic kidney disease but the mechanisms that regulate the activation of the endothelium at the early stages of the disease, before systemic inflammation is established remain obscure. In the present study we investigated the effect of serum derived from patients with chronic kidney disease either before or after hemodialysis on the activation of human endothelial cells in vitro, as an attempt to define the overall effect of uremic toxins at the early stages of endothelial dysfunction. Our results argue that uremic toxins alter the biological actions of endothelial cells and the remodelling of the extracellular matrix before signs of systemic inflammatory responses are observed. This study further elucidates the early events of endothelial dysfunction during toxic uremia conditions allowing more complete understanding of the molecular events as well as their sequence during progressive renal failure
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