686 research outputs found

    A Microfluidic Chamber for Analysis of Neuron-to-Cell Spread and Axonal Transport of an Alpha-Herpesvirus

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    Alpha-herpesviruses, including herpes simplex virus and pseudorabies virus (PRV), infect the peripheral nervous system (PNS) of their hosts. Here, we describe an in vitro method for studying neuron-to-cell spread of infection as well as viral transport in axons. The method centers on a novel microfluidic chamber system that directs growth of axons into a fluidically isolated environment. The system uses substantially smaller amounts of virus inoculum and media than previous chamber systems and yet offers the flexibility of applying multiple virology and cell biology assays including live-cell optical imaging. Using PRV infection of cultured PNS neurons, we demonstrate that the microfluidic chamber recapitulates all known facets of neuron-to-cell spread demonstrated in animals and other compartmented cell systems

    Correlates of quality of life in overweight or obese breast cancer survivors at enrollment into a weight loss trial

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    OBJECTIVE: To examine the correlates of the physical and psychosocial domains of quality of life (QOL) in a cohort of breast cancer survivors participating in a weight loss intervention trial. Available data included information on weight and physical activity, as well as demographic and medical characteristics. METHODS: Correlates of QOL and psychosocial functioning were examined in 692 overweight/obese breast cancer survivors at entry into a weight loss trial. QOL was explored with three measures: Short-form 36 (SF-36); Impact of Cancer Scale (IOCv2); and the Breast Cancer Prevention Trial (BCPT) Symptom Scales. Bivariate and multivariate analyses were used to identify correlates and associations adjusted for other characteristics. RESULTS: In multivariate analysis, younger age was associated with higher negative impact scores (p<0.01). Hispanic, African-American and Asian women had higher IOC positive impact scores compared to white non-Hispanic women (p<0.01). Higher education was associated with lower scores on mental QOL and the IOC positive impact scale (p<0.01). BMI was not independently associated with QOL measures. Physical activity was directly associated with physical and mental QOL and IOC positive impact, and inversely related to IOC negative impact and BCPT symptom scales. CONCLUSIONS: QOL measures in breast cancer survivors are differentially associated with demographic and other characteristics. When adjusted for these characteristics, degree of adiposity among overweight/obese women does not appear to be independently associated with QOL. Among overweight/obese breast cancer survivors, higher level of physical activity is associated with higher QOL across various scales and dimensions

    Organic–inorganic interfaces and spiral growth in nacre

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    Nacre, the crown jewel of natural materials, has been extensively studied owing to its remarkable physical properties for over 160 years. Yet, the precise structural features governing its extraordinary strength and its growth mechanism remain elusive. In this paper, we present a series of observations pertaining to the red abalone (Haliotis rufescens) shell's organic–inorganic interface, organic interlayer morphology and properties, large-area crystal domain orientations and nacre growth. In particular, we describe unique lateral nano-growths and paired screw dislocations in the aragonite layers, and demonstrate that the organic material sandwiched between aragonite platelets consists of multiple organic layers of varying nano-mechanical resilience. Based on these novel observations and analysis, we propose a spiral growth model that accounts for both [001] vertical propagation via helices that surround numerous screw dislocation cores and simultaneous 〈010〉 lateral growth of aragonite sheet structure. These new findings may aid in creating novel organic–inorganic micro/nano composites through synthetic or biomineralization pathways

    Shaping electron wave functions in a carbon nanotube with a parallel magnetic field

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    A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.Comment: 5 figure

    Distinct Clinical and Pathological Features Are Associated with the BRAFT1799A(V600E) Mutation in Primary Melanoma

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    The BRAFT1799A mutation encodes BRAFV600E that leads to activation of the mitogen-activated protein kinase pathway. This study aimed to assess the clinico-pathological features of primary invasive melanomas containing the BRAFT1799A mutation. Patients (n=251) with invasive primary melanomas from Australia were interviewed and examined with respect to their melanoma characteristics and risk factors. Independent review of pathology, allele-specific PCR for the BRAFT1799A mutation, immunohistochemical staining with Ki67, and phospho-histone-H3 (PH3) were performed. The BRAFT1799A mutation was found in 112 (45%) of the primary melanomas. Associations with the BRAFT1799A mutation (P<0.05) were as follows: low tumor thickness (odds ratio (OR)=3.3); low mitotic rate (OR=2.0); low Ki67 score (OR=5.0); low PH3 score (OR=3.3); superficial spreading melanoma (OR=10.0); pigmented melanoma (OR=3.7); a lack of history of solar keratoses (OR=2.7); a location on the trunk (OR=3.4) or extremity (OR=2.0); a high level of self-reported childhood sun exposure (OR=2.0); ≤50 years of age (OR=2.5); and fewer freckles (OR=2.5). We conclude that the BRAFT1799A mutation has associations with host phenotype, tumor location, and pigmentation. Although implicated in the control of the cell cycle, the BRAFT1799A mutation is associated with a lower rate of tumor proliferation

    Role of Isoprenoid Lipids on the Heterotrimeric G Protein γ Subunit in Determining Effector Activation

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    Post-translational prenylation of heterotrimeric G protein gamma subunits is essential for high affinity alpha-beta gamma and alpha-beta gamma-receptor interactions, suggesting that the prenyl group is an important domain in the beta gamma dimer. To determine the role of the prenyl modification in the interaction of beta gamma dimers with effectors, the CAAX (where A indicates alipathic amino acid) motifs in the gamma1, gamma2, and gamma11 subunits were altered to direct modification with different prenyl groups. Six recombinant beta gamma dimers were overexpressed in baculovirus-infected Sf9 insect cells, purified, and examined for their ability to stimulate three phospholipase C-beta isozymes and type II adenylyl cyclase. The native beta1 gamma2 dimer (gamma subunit modified with geranylgeranyl) is more potent and effective in activating phospholipase C-beta than either the beta1 gamma1 (farnesyl) or the beta1 gamma11 (farnesyl) dimers. However, farnesyl modification of the gamma subunit in the beta1 gamma2 dimer (beta1 gamma2-L71S) caused a decrement in its ability to activate phospholipase C-beta. In contrast, both the beta1 gamma1-S74L (geranylgeranyl) and the beta1 gamma11-S73L (geranylgeranyl) dimers were more active than the native forms. The beta1 gamma2 dimer activates type II adenylyl cyclase about 12-fold; however, neither the beta1 gamma1 nor the beta1 gamma11 dimers activate the enzyme. As was the case with phospholipase C-beta, the beta1gamma2-L71S dimer was less able to activate adenylyl cyclase than the native beta1 gamma2 dimer. Interestingly, neither the beta1 gamma1-S74L nor the beta1 gamma11-S73L dimers stimulated adenylyl cyclase. The results suggest that both the amino acid sequence of the gamma subunit and its prenyl group play a role in determining the activity of the beta gamma-effector complex

    Dynamic jamming of iceberg-choked fjords

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    We investigate the dynamics of ice mélange by analyzing rapid motion recorded by a time-lapse camera and terrestrial radar during several calving events that occurred at Jakobshavn Isbræ, Greenland. During calving events (1) the kinetic energy of the ice mélange is 2 orders of magnitude smaller than the total energy released during the events, (2) a jamming front propagates through the ice mélange at a rate that is an order of magnitude faster than the motion of individual icebergs, (3) the ice mélange undergoes initial compaction followed by slow relaxation and extension, and (4) motion of the ice mélange gradually decays before coming to an abrupt halt. These observations indicate that the ice mélange experiences widespread jamming during calving events and is always close to being in a jammed state during periods of terminus quiescence. We therefore suspect that local jamming influences longer timescale ice mélange dynamics and stress transmission

    A comparative analysis of algorithms for somatic SNV detection in cancer

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    Motivation: With the advent of relatively affordable high-throughput technologies, DNA sequencing of cancers is now common practice in cancer research projects and will be increasingly used in clinical practice to inform diagnosis and treatment. Somatic (cancer-only) single nucleotide variants (SNVs) are the simplest class of mutation, yet their identification in DNA sequencing data is confounded by germline polymorphisms, tumour heterogeneity and sequencing and analysis errors. Four recently published algorithms for the detection of somatic SNV sites in matched cancer–normal sequencing datasets are VarScan, SomaticSniper, JointSNVMix and Strelka. In this analysis, we apply these four SNV calling algorithms to cancer–normal Illumina exome sequencing of a chronic myeloid leukaemia (CML) patient. The candidate SNV sites returned by each algorithm are filtered to remove likely false positives, then characterized and compared to investigate the strengths and weaknesses of each SNV calling algorithm. Results: Comparing the candidate SNV sets returned by VarScan, SomaticSniper, JointSNVMix2 and Strelka revealed substantial differences with respect to the number and character of sites returned; the somatic probability scores assigned to the same sites; their susceptibility to various sources of noise; and their sensitivities to low-allelic-fraction candidates.Nicola D. Roberts, R. Daniel Kortschak, Wendy T. Parker, Andreas W. Schreiber, Susan Branford, Hamish S. Scott, Garique Glonek and David L. Adelso

    The ESR1 (6q25) locus is associated with calcaneal ultrasound parameters and radial volumetric bone mineral density in European men

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    &lt;p&gt;&lt;b&gt;Purpose:&lt;/b&gt; Genome-wide association studies (GWAS) have identified 6q25, which incorporates the oestrogen receptor alpha gene (ESR1), as a quantitative trait locus for areal bone mineral density (BMD(a)) of the hip and lumbar spine. The aim of this study was to determine the influence of this locus on other bone health outcomes; calcaneal ultrasound (QUS) parameters, radial peripheral quantitative computed tomography (pQCT) parameters and markers of bone turnover in a population sample of European men.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methods:&lt;/b&gt; Eight single nucleotide polymorphisms (SNP) in the 6q25 locus were genotyped in men aged 40-79 years from 7 European countries, participating in the European Male Ageing Study (EMAS). The associations between SNPs and measured bone parameters were tested under an additive genetic model adjusting for centre using linear regression.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Results:&lt;/b&gt; 2468 men, mean (SD) aged 59.9 (11.1) years had QUS measurements performed and bone turnover marker levels measured. A subset of 628 men had DXA and pQCT measurements. Multiple independent SNPs showed significant associations with BMD using all three measurement techniques. Most notably, rs1999805 was associated with a 0.10 SD (95%CI 0.05, 0.16; p = 0.0001) lower estimated BMD at the calcaneus, a 0.14 SD (95%CI 0.05, 0.24; p = 0.004) lower total hip BMD(a), a 0.12 SD (95%CI 0.02, 0.23; p = 0.026) lower lumbar spine BMD(a) and a 0.18 SD (95%CI 0.06, 0.29; p = 0.003) lower trabecular BMD at the distal radius for each copy of the minor allele. There was no association with serum levels of bone turnover markers and a single SNP which was associated with cortical density was also associated with cortical BMC and thickness.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions:&lt;/b&gt; Our data replicate previous associations found between SNPs in the 6q25 locus and BMD(a) at the hip and extend these data to include associations with calcaneal ultrasound parameters and radial volumetric BMD.&lt;/p&gt
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