292 research outputs found

    NADPH oxidase, NOX1, mediates vascular injury in ischemic retinopathy

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    <b>Aims:</b> Ischemic retinal diseases such as retinopathy of prematurity are major causes of blindness due to damage to the retinal microvasculature. Despite this clinical situation, retinopathy of prematurity is mechanistically poorly understood. Therefore, effective preventative therapies are not available. However, hypoxic-induced increases in reactive oxygen species (ROS) have been suggested to be involved with NADPH oxidases (NOX), the only known dedicated enzymatic source of ROS. Our major aim was to determine the contribution of NOX isoforms (1, 2, and 4) to a rodent model of retinopathy of prematurity. <b>Results:</b> Using a genetic approach, we determined that only mice with a deletion of NOX1, but not NOX2 or NOX4, were protected from retinal neovascularization and vaso-obliteration, adhesion of leukocytes, microglial accumulation, and the increased generation of proangiogenic and proinflammatory factors and ROS. We complemented these studies by showing that the specific NOX inhibitor, GKT137831, reduced vasculopathy and ROS levels in retina. The source of NOX isoforms was evaluated in retinal vascular cells and neuro-glial elements. Microglia, the immune cells of the retina, expressed NOX1, 2, and 4 and responded to hypoxia with increased ROS formation, which was reduced by GKT137831. <b>Innovation:</b> Our studies are the first to identify the NOX1 isoform as having an important role in the pathogenesis of retinopathy of prematurity. <b>Conclusions:</b> Our findings suggest that strategies targeting NOX1 have the potential to be effective treatments for a range of ischemic retinopathie

    Patterns of hepatitis B prevalence and seroconversion in hemodialysis units from three continents: The DOPPS

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    Patterns of hepatitis B prevalence and seroconversion in hemodialysis units from three continents: The DOPPS.BackgroundHepatitis B (HBV) historically has been a public health issue within hemodialysis units. This study estimates HBV prevalence and seroconversion rates across seven countries and investigates associations with facility level practice patterns.MethodsThe study sample was from the Dialysis Outcomes and Practice Patterns Study (DOPPS), a cross-sectional, prospective, observational study of adult hemodialysis patients randomly selected from 308 dialysis facilities in France, Germany, Italy, Spain, the United Kingdom, Japan, and the United States. Logistic regression was used to model the odds ratio (OR) of HBV prevalence, and Cox regression was used to model time from entry into the study to HBV seroconversion.ResultsIn this sample, mean HBV facility prevalence was 3.0% with a median of 1.9%. The percentage of facilities with an HBV prevalence 0% to 5% was 78.5%. Adjusted HBV prevalence was higher in France, Germany, and Italy and lower in Japan and the United Kingdom. The majority of facilities (78.1%) had a seroconversion rate of 0 conversions per 100 patient-years. Presence of a protocol for HBV-infected patients was significantly associated with HBV seroconversion in the separate practice pattern model [risk ratio (RR) = 0.52, P = 0.03] and in the combined practice pattern model (RR = 0.44, P = 0.01).ConclusionThere are differences in HBV prevalence and rate of seroconversion both at the country and the hemodialysis facility level. Presence of a protocol for HBV-infected patients was strongly and significantly associated with decreased risk for seroconversion. The observed variation suggests opportunities for improved HBV outcomes with further definition of optimal practice patterns at the facility level

    The Infrared Imaging Spectrograph (IRIS) for TMT: Instrument Overview

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    We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron) integral field spectrograph and imaging camera for the Thirty Meter Telescope (TMT). With extremely low wavefront error (<30 nm) and on-board wavefront sensors, IRIS will take advantage of the high angular resolution of the narrow field infrared adaptive optics system (NFIRAOS) to dissect the sky at the diffraction limit of the 30-meter aperture. With a primary spectral resolution of 4000 and spatial sampling starting at 4 milliarcseconds, the instrument will create an unparalleled ability to explore high redshift galaxies, the Galactic center, star forming regions and virtually any astrophysical object. This paper summarizes the entire design and basic capabilities. Among the design innovations is the combination of lenslet and slicer integral field units, new 4Kx4k detectors, extremely precise atmospheric dispersion correction, infrared wavefront sensors, and a very large vacuum cryogenic system.Comment: Proceedings of the SPIE, 9147-76 (2014

    Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

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    To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity and therefore probability to detect planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.Comment: 10 pages, 5 figures, 1 table; ApJ in pres

    Nonadherence in hemodialysis: Associations with mortality, hospitalization, and practice patterns in the DOPPS

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    Nonadherence in hemodialysis: Associations with mortality, hospitalization, and practice patterns in the DOPPS.BackgroundNonadherence among hemodialysis patients compromises dialysis delivery, which could influence patient morbidity and mortality. The Dialysis Outcomes and Practice Patterns Study (DOPPS) provides a unique opportunity to review this problem and its determinants on a global level.MethodsNonadherence was studied using data from the DOPPS, an international, observational, prospective hemodialysis study. Patients were considered nonadherent if they skipped one or more sessions per month, shortened one or more sessions by more than 10 minutes per month, had a serum potassium level openface>6.0mEq/L, a serum phosphate level openface>7.5mg/dL (>2.4mmol/L), or interdialytic weight gain (IDWG)>5.7% of body weight. Predictors of nonadherence were identified using logistic regression. Survival analysis used the Cox proportional hazards model adjusting for case-mix.ResultsSkipping treatment was associated with increased mortality [relative risk (RR) = 1.30, P = 0.01], as were excessive IDWG (RR = 1.12, P = 0.047) and high phosphate levels (RR = 1.17, P = 0.001). Skipping also was associated with increased hospitalization (RR = 1.13, P = 0.04), as were high phosphate levels (RR = 1.07, P = 0.05). Larger facility size (per 10 patients) was associated with higher odds ratios (OR) of skipping (OR = 1.03, P = 0.06), shortening (OR = 1.03, P = 0.05), and IDWG (OR = 1.02, P = 0.07). An increased percentage of highly trained staff hours was associated with lower OR of skipping (OR = 0.84 per 10%, P = 0.02); presence of a dietitian was associated with lower OR of excessive IDWG (OR = 0.75, P = 0.08).ConclusionNonadherence was associated with increased mortality risk (skipping treatment, excessive IDWG, and high phosphate) and with hospitalization risk (skipping, high phosphate). Certain patient/facility characteristics also were associated with nonadherence

    The infrared imaging spectrograph (IRIS) for TMT: status report for IRIS imager

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    The current status of IRIS imager at NAOJ is reported. IRIS (Infrared Imaging Spectrograph) is a first light instrument of TMT (Thirty Meter Telescope). IRIS has just passed the preliminary design review and moved forward to the final design phase. In this paper, optical and mechanical design of IRIS imager and prototyping activities conducted during the preliminary design phase are summarized

    Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction Curve

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    We combine VI photometry from OGLE-III with VVV and 2MASS measurements of E(J-K_{s}) to resolve the longstanding problem of the non-standard optical extinction toward the Galactic bulge. We show that the extinction is well-fit by the relation A_{I} = 0.7465*E(V-I) + 1.3700*E(J-K_{s}), or, equivalently, A_{I} = 1.217*E(V-I)(1+1.126*(E(J-K_{s})/E(V-I)-0.3433)). The optical and near-IR reddening law toward the inner Galaxy approximately follows an R_{V} \approx 2.5 extinction curve with a dispersion {\sigma}_{R_{V}} \approx 0.2, consistent with extragalactic investigations of the hosts of type Ia SNe. Differential reddening is shown to be significant on scales as small as as our mean field size of 6', with the 1{\sigma} dispersion in reddening averaging 9% of total reddening for our fields. The intrinsic luminosity parameters of the Galactic bulge red clump (RC) are derived to be (M_{I,RC}, \sigma_{I,RC,0}, (V-I)_{RC,0}, \sigma_{(V-I)_{RC}}, (J-K_{s})_{RC,0}) = (-0.12, 0.09, 1.06, 0.121, 0.66). Our measurements of the RC brightness, brightness dispersion and number counts allow us to estimate several Galactic bulge structural parameters. We estimate a distance to the Galactic center of 8.20 kpc, resolving previous discrepancies in distance determinations to the bulge based on I-band observations. We measure an upper bound on the tilt {\alpha} \approx 40{\deg}. between the bar's major axis and the Sun-Galactic center line of sight, though our brightness peaks are consistent with predictions of an N-body model oriented at {\alpha} \approx 25{\deg}. The number of RC stars suggests a total stellar mass for the Galactic bulge of 2.0*10^{10} M_{\odot}, if one assumes a Salpeter IMF.Comment: 61 Pages, 21 Figures, 4 Tables, Submitted to The Astrophysical Journal and modified as per a referee report. Includes reddening, reddening law, differential reddening, mean distance, dispersion in distance, surface density of stars and errors thereof for ~9,000 bulge sightlines. For a brief video explaining the key result of this paper, see http://www.youtube.com/user/OSUAstronom

    Specific Binding and Mineralization of Calcified Surfaces by Small Peptides

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    Several small (<25aa) peptides have been designed based on the sequence of the dentin phosphoprotein, one of the major noncollagenous proteins thought to be involved in the mineralization of the dentin extracellular matrix during tooth development. These peptides, consisting of multiple repeats of the tripeptide aspartate-serine-serine (DSS), bind with high affinity to calcium phosphate compounds and, when immobilized, can recruit calcium phosphate to peptide-derivatized polystyrene beads or to demineralized human dentin surfaces. The affinity of binding to hydroxyapatite surfaces increases with the number of (DSS)n repeats, and though similar repeated sequences—(NTT)n, (DTT)n, (ETT)n, (NSS)n, (ESS)n, (DAA)n, (ASS)n, and (NAA)n—also showed HA binding activity, it was generally not at the same level as the natural sequence. Binding of the (DSS)n peptides to sectioned human teeth was shown to be tissue-specific, with high levels of binding to the mantle dentin, lower levels of binding to the circumpulpal dentin, and little or no binding to healthy enamel. Phosphorylation of the serines of these peptides was found to affect the avidity, but not the affinity, of binding. The potential utility of these peptides in the detection of carious lesions, the delivery of therapeutic compounds to mineralized tissues, and the modulation of remineralization is discussed

    Toll-like receptor signaling adapter proteins govern spread of neuropathic pain and recovery following nerve injury in male mice.

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    BackgroundSpinal Toll-like receptors (TLRs) and signaling intermediaries have been implicated in persistent pain states. We examined the roles of two major TLR signaling pathways and selected TLRs in a mononeuropathic allodynia.MethodsL5 spinal nerve ligation (SNL) was performed in wild type (WT, C57BL/6) male and female mice and in male Tlr2-/-Tlr3-/-, Tlr4-/-, Tlr5-/-, Myd88-/-, Triflps2, Myd88/Triflps2, Tnf-/-, and Ifnar1-/- mice. We also examined L5 ligation in Tlr4-/- female mice. We examined tactile allodynia using von Frey hairs. Iba-1 (microglia) and GFAP (astrocytes) were assessed in spinal cords by immunostaining. Tactile thresholds were analyzed by 1- and 2-way ANOVA and the Bonferroni post hoc test was used.ResultsIn WT male and female mice, SNL lesions resulted in a persistent and robust ipsilateral, tactile allodynia. In males with TLR2, 3, 4, or 5 deficiencies, tactile allodynia was significantly, but incompletely, reversed (approximately 50%) as compared to WT. This effect was not seen in female Tlr4-/- mice. Increases in ipsilateral lumbar Iba-1 and GFAP were seen in mutant and WT mice. Mice deficient in MyD88, or MyD88 and TRIF, showed an approximately 50% reduction in withdrawal thresholds and reduced ipsilateral Iba-1. In contrast, TRIF and interferon receptor null mice developed a profound ipsilateral and contralateral tactile allodynia. In lumbar sections of the spinal cords, we observed a greater increase in Iba-1 immunoreactivity in the TRIF-signaling deficient mice as compared to WT, but no significant increase in GFAP. Removing MyD88 abrogated the contralateral allodynia in the TRIF signaling-deficient mice. Conversely, IFNβ, released downstream to TRIF signaling, administered intrathecally, temporarily reversed the tactile allodynia.ConclusionsThese observations suggest a critical role for the MyD88 pathway in initiating neuropathic pain, but a distinct role for the TRIF pathway and interferon in regulating neuropathic pain phenotypes in male mice
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