97 research outputs found

    Observation of unidirectional backscattering-immune topological electromagnetic states

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    One of the most striking phenomena in condensed-matter physics is the quantum Hall effect, which arises in two-dimensional electron systems subject to a large magnetic field applied perpendicular to the plane in which the electrons reside. In such circumstances, current is carried by electrons along the edges of the system, in so-called chiral edge states (CESs). These are states that, as a consequence of nontrivial topological properties of the bulk electronic band structure, have a unique directionality and are robust against scattering from disorder. Recently, it was theoretically predicted that electromagnetic analogues of such electronic edge states could be observed in photonic crystals, which are materials having refractive-index variations with a periodicity comparable to the wavelength of the light passing through them. Here we report the experimental realization and observation of such electromagnetic CESs in a magneto-optical photonic crystal fabricated in the microwave regime. We demonstrate that, like their electronic counterparts, electromagnetic CESs can travel in only one direction and are very robust against scattering from disorder; we find that even large metallic scatterers placed in the path of the propagating edge modes do not induce reflections. These modes may enable the production of new classes of electromagnetic device and experiments that would be impossible using conventional reciprocal photonic states alone. Furthermore, our experimental demonstration and study of photonic CESs provides strong support for the generalization and application of topological band theories to classical and bosonic systems, and may lead to the realization and observation of topological phenomena in a generally much more controlled and customizable fashion than is typically possible with electronic systems

    The E1A-Associated p400 Protein Modulates Cell Fate Decisions by the Regulation of ROS Homeostasis

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    The p400 E1A-associated protein, which mediates H2A.Z incorporation at specific promoters, plays a major role in cell fate decisions: it promotes cell cycle progression and inhibits induction of apoptosis or senescence. Here, we show that p400 expression is required for the correct control of ROS metabolism. Depletion of p400 indeed increases intracellular ROS levels and causes the appearance of DNA damage, indicating that p400 maintains oxidative stress below a threshold at which DNA damages occur. Suppression of the DNA damage response using a siRNA against ATM inhibits the effects of p400 on cell cycle progression, apoptosis, or senescence, demonstrating the importance of ATM–dependent DDR pathways in cell fates control by p400. Finally, we show that these effects of p400 are dependent on direct transcriptional regulation of specific promoters and may also involve a positive feedback loop between oxidative stress and DNA breaks since we found that persistent DNA breaks are sufficient to increase ROS levels. Altogether, our results uncover an unexpected link between p400 and ROS metabolism and allow deciphering the molecular mechanisms largely responsible for cell proliferation control by p400

    Influenza burden, prevention and treatment in asthma – a scoping review by the EAACI Influenza in Asthma Task Force

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    To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma

    Eosinophils in glioblastoma biology

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    Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults. The development of this malignant glial lesion involves a multi-faceted process that results in a loss of genetic or epigenetic gene control, un-regulated cell growth, and immune tolerance. Of interest, atopic diseases are characterized by a lack of immune tolerance and are inversely associated with glioma risk. One cell type that is an established effector cell in the pathobiology of atopic disease is the eosinophil. In response to various stimuli, the eosinophil is able to produce cytotoxic granules, neuromediators, and pro-inflammatory cytokines as well as pro-fibrotic and angiogenic factors involved in pathogen clearance and tissue remodeling and repair. These various biological properties reveal that the eosinophil is a key immunoregulatory cell capable of influencing the activity of both innate and adaptive immune responses. Of central importance to this report is the observation that eosinophil migration to the brain occurs in response to traumatic brain injury and following certain immunotherapeutic treatments for GBM. Although eosinophils have been identified in various central nervous system pathologies, and are known to operate in wound/repair and tumorstatic models, the potential roles of eosinophils in GBM development and the tumor immunological response are only beginning to be recognized and are therefore the subject of the present review

    Pan-cancer analysis of whole genomes

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    Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

    T-cell identity and epigenetic memory

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    T-cell development endows cells with a flexible range of effector differentiation options, superimposed on a stable core of lineage-specific gene expression that is maintained while access to alternative hematopoietic lineages is permanently renounced. This combination of features could be explained by environmentally responsive transcription factor mobilization overlaying an epigenetically stabilized base gene expression state. For example, "poising" of promoters could offer preferential access to T-cell genes, while repressive histone modifications and DNA methylation of non-T regulatory genes could be responsible for keeping non-T developmental options closed. Here, we critically review the evidence for the actual deployment of epigenetic marking to support the stable aspects of T-cell identity. Much of epigenetic marking is dynamically maintained or subject to rapid modification by local action of transcription factors. Repressive histone marks are used in gene-specific ways that do not fit a simple, developmental lineage-exclusion hierarchy. We argue that epigenetic analysis may achieve its greatest impact for illuminating regulatory biology when it is used to locate cis-regulatory elements by catching them in the act of mediating regulatory change

    Dyslipidaemia in patients with lupus nephritis

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    Aim: There is little data on the prevalence and severity of dyslipidaemia in Asian patients with lupus nephritis (LN). Whether the dyslipidaemia in LN patients differs from subjects with comparable levels of renal impairment also remains undefined. Methods: Lipid profiles of 100 Chinese patients with quiescent LN (age 46.3 ± 9.3 years, 83% female, maintenance prednisolone dose 5.80 ± 2.43 mg/day) were studied and compared with 100 controls who had non-lupus non-diabetic chronic kidney diseases (CKD), matched for sex, age and renal function. Results: LN patients and CKD controls had similar renal function and proteinuria, while blood pressure was higher in controls. Twenty-five percent of LN patients and 17% of controls were receiving statin treatment. Despite this, 59% of LN patients and 46% CKD controls showed abnormal lipid parameters (P = 0.066). LN patients showed higher levels of total cholesterol (TC) and triglycerides (TG) than controls (5.28 ± 0.12 vs 4.86 ± 0.08 mmol/L, P = 0.004; and 1.62 ± 0.12 vs 1.20 ± 0.07 mmol/L, P = 0.002, respectively). More LN patients had abnormal TC, TG or low-density lipoprotein cholesterol (LDL-C) (54%, 16% and 38%; P = 0.016, = 0.005 and = 0.021, respectively). Hydroxychloroquine (HCQ) treatment was associated with lower TC, LDL-C and HDL-cholesterol. Conclusion: Dyslipidaemia is prevalent in LN patients and is more severe than controls with a similar degree of CKD despite disease quiescence, low steroid dose and low level of proteinuria. Concomitant corticosteroid and renal impairment are likely contributing factors. HCQ treatment is associated with reduced severity of dyslipidaemia in LN patients. Both systemic lupus erythematosus and chronic kidney disease are associated with excess vascular mortality. In this significant cohort of Asian patients with lupus nephritis, Chong et al. show that dyslipidaemia is common, even in inactive lupus nephritis, more common than in controls with a similar degree of chronic kidney disease. © 2011 Asian Pacific Society of Nephrology.link_to_subscribed_fulltex

    Measurement equivalence of the English, Chinese and Malay versions of the World Health Organization quality of life (WHOQOL-BREF) questionnaires

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    10.1186/s12955-019-1130-0Health and Quality of Life Outcomes1716
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