52 research outputs found
The Lick AGN Monitoring Project: Alternate Routes to a Broad-line Region Radius
It is now possible to estimate black hole masses across cosmic time, using
broad emission lines in active galaxies. This technique informs our views of
how galaxies and their central black holes coevolve. Unfortunately, there are
many outstanding uncertainties associated with these "virial" mass estimates.
One of these comes from using the accretion luminosity to infer a size for the
broad-line region. Incorporating the new sample of low-luminosity active
galaxies from our recent monitoring campaign at Lick Observatory, we
recalibrate the radius-luminosity relation with tracers of the accretion
luminosity other than the optical continuum. We find that the radius of the
broad-line region scales as the square root of the X-ray and Hbeta
luminosities, in agreement with recent optical studies. On the other hand, the
scaling appears to be marginally steeper with narrow-line luminosities. This is
consistent with a previously observed decrease in the ratio of narrow-line to
X-ray luminosity with increasing total luminosity. The radius of the broad-line
region correlates most tightly with Hbeta luminosity, while the X-ray and
narrow-line relations both have comparable scatter of a factor of two. These
correlations provide useful alternative virial BH masses in objects with no
detectable optical/UV continuum emission, such as high-redshift galaxies with
broad emission lines, radio-loud objects, or local active galaxies with
galaxy-dominated continua.Comment: 8 pages, 1 figure, accepted for publication in Ap
The Lick AGN Monitoring Project: Broad-Line Region Radii and Black Hole Masses from Reverberation Mapping of Hbeta
We have recently completed a 64-night spectroscopic monitoring campaign at
the Lick Observatory 3-m Shane telescope with the aim of measuring the masses
of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected
masses in the range ~10^6-10^7 M_sun and also the well-studied nearby active
galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including
NGC 5548) showed optical variability of sufficient strength during the
monitoring campaign to allow for a time lag to be measured between the
continuum fluctuations and the response to these fluctuations in the broad
Hbeta emission. We present here the light curves for the objects in this sample
and the subsequent Hbeta time lags for the nine objects where these
measurements were possible. The Hbeta lag time is directly related to the size
of the broad-line region, and by combining the lag time with the measured width
of the Hbeta emission line in the variable part of the spectrum, we determine
the virial mass of the central supermassive black hole in these nine AGNs. The
absolute calibration of the black hole masses is based on the normalization
derived by Onken et al. We also examine the time lag response as a function of
velocity across the Hbeta line profile for six of the AGNs. The analysis of
four leads to ambiguous results with relatively flat time lags as a function of
velocity. However, SBS 1116+583A exhibits a symmetric time lag response around
the line center reminiscent of simple models for circularly orbiting broad-line
region (BLR) clouds, and Arp 151 shows an asymmetric profile that is most
easily explained by a simple gravitational infall model. Further investigation
will be necessary to fully understand the constraints placed on physical models
of the BLR by the velocity-resolved response in these objects.Comment: 24 pages, 16 figures and 13 tables, submitted to Ap
The predictive role of symptoms in COVID-19 diagnostic models : A longitudinal insight
Acknowledgements 2019nCoV-302 Study Group Members: The NVX-CoV2373-2019nCoV-302 clinical trial was a collective group effort across multiple institutions and locations. Below is a list of sites and staff that significantly contributed to the implementation and conduct of the NVX-CoV2373-2019nCoV-302 clinical trial.Peer reviewe
Safety and efficacy of the NVX-CoV2373 coronavirus disease 2019 vaccine at completion of the placebo-controlled phase of a randomized controlled trial
Background: The recombinant protein-based vaccine, NVX-CoV2373, demonstrated 89.7% efficacy against coronavirus disease 2019 (COVID-19) in a phase 3, randomized, observer-blinded, placebo-controlled trial in the United Kingdom. The protocol was amended to include a blinded crossover. Data to the end of the placebo-controlled phase are reported.
Methods: Adults aged 18–84 years received 2 doses of NVX-CoV2373 or placebo (1:1) and were monitored for virologically confirmed mild, moderate, or severe COVID-19 (onset from 7 days after second vaccination). Participants who developed immunoglobulin G (IgG) against nucleocapsid protein but did not show symptomatic COVID-19 were considered asymptomatic. Secondary outcomes included anti-spike (S) IgG responses, wild-type virus neutralization, and T-cell responses.
Results: Of 15 185 participants, 13 989 remained in the per-protocol efficacy population (6989 NVX-CoV2373, 7000 placebo). At a maximum of 7.5 months (median, 4.5) postvaccination, there were 24 cases of COVID-19 among NVX-CoV2373 recipients and 134 cases among placebo recipients, a vaccine efficacy of 82.7% (95% confidence interval [CI], 73.3%–88.8%). Vaccine efficacy was 100% (95% CI, 17.9%–100.0%) against severe disease and 76.3% (95% CI, 57.4%–86.8%) against asymptomatic disease. High anti-S and neutralization responses to vaccination were evident, together with S-protein–specific induction of interferon-γ secretion in peripheral blood T cells. Incidence of serious adverse events and adverse events of special interest were similar between groups.
Conclusions: A 2-dose regimen of NVX-CoV2373 conferred a high level of ongoing protection against asymptomatic, symptomatic, and severe COVID-19 through >6 months postvaccination. A gradual decrease of protection suggests that a booster may be indicated.
Clinical Trials Registration: EudraCT, 2020-004123-16
Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial
Background
Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy
Safety and Efficacy of the NVX-CoV2373 Coronavirus Disease 2019 Vaccine at Completion of the Placebo-Controlled Phase of a Randomized Controlled Trial
Acknowledgements The study and article were funded by Novavax. We would like to thank all the study participants for their commitment to this study. We also acknowledge the investigators and their study teams for their hard work and dedication. In addition, we would like to thank the National Institute for Health Research, representatives from the Department of Health and Social Care laboratories and NHS Digital and the members of the UK Vaccine Task Force. Editorial support was provided by Kelly Cameron of Ashfield MedComms, an Inizio company Funding This work was funded by Novavax, and the sponsor had primary responsibility for study design, study vaccines, protocol development, study monitoring, data management, and statistical analyses. All authors reviewed and approved the manuscript before submission. LF reports a position as a prior full-time employee, now contractor to Novavax re-imbursed hourly for work performed on this study and in analyses and drafting this report. IC reports providing medical writing support for this work as an employee of NovavaxPeer reviewedPublisher PD
Safety and efficacy of the NVX-CoV2373 coronavirus disease 2019 vaccine at completion of the placebo-controlled phase of a randomized controlled trial
Background:
The recombinant protein-based vaccine, NVX-CoV2373, demonstrated 89.7% efficacy against coronavirus disease 2019 (COVID-19) in a phase 3, randomized, observer-blinded, placebo-controlled trial in the United Kingdom. The protocol was amended to include a blinded crossover. Data to the end of the placebo-controlled phase are reported.
Methods:
Adults aged 18–84 years received 2 doses of NVX-CoV2373 or placebo (1:1) and were monitored for virologically confirmed mild, moderate, or severe COVID-19 (onset from 7 days after second vaccination). Participants who developed immunoglobulin G (IgG) against nucleocapsid protein but did not show symptomatic COVID-19 were considered asymptomatic. Secondary outcomes included anti-spike (S) IgG responses, wild-type virus neutralization, and T-cell responses.
Results:
Of 15 185 participants, 13 989 remained in the per-protocol efficacy population (6989 NVX-CoV2373, 7000 placebo). At a maximum of 7.5 months (median, 4.5) postvaccination, there were 24 cases of COVID-19 among NVX-CoV2373 recipients and 134 cases among placebo recipients, a vaccine efficacy of 82.7% (95% confidence interval [CI], 73.3%–88.8%). Vaccine efficacy was 100% (95% CI, 17.9%–100.0%) against severe disease and 76.3% (95% CI, 57.4%–86.8%) against asymptomatic disease. High anti-S and neutralization responses to vaccination were evident, together with S-protein–specific induction of interferon-γ secretion in peripheral blood T cells. Incidence of serious adverse events and adverse events of special interest were similar between groups.
Conclusions:
A 2-dose regimen of NVX-CoV2373 conferred a high level of ongoing protection against asymptomatic, symptomatic, and severe COVID-19 through >6 months postvaccination. A gradual decrease of protection suggests that a booster may be indicated
Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study
Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation
Impact of limited treadmill exercise on adenosine Tc-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging in coronary artery disease
Limited exercise combined with dipyridamole increases myocardial perfusion defect severity compared with dipyridamole alone. The impact of limited exercise combined with adenosine on myocardial perfusion defect severity is unknown. This study compares myocardial perfusion defect severity with adenosine alone and adenosine combined with limited exercise. Thirty-two patients with coronary artery disease underwent on separate days and in randomized order technetium-99m sestamibi (25 to 30 mCi) single-photon emission computed tomographic imaging at rest, after adenosine (140 μg/kg/min × 6 minutes), and after adenosine (140 μg/kg/min × 4 minutes) during 6 minutes of modified Bruce treadmill exercise (adenosine-exercise). Radiopharmaceutical was injected at 3 and 5 minutes during adenosine and adenosine-exercise, respectively. Images were interpreted by a consensus agreement of 3 nuclear cardiologists without knowledge of patient identity, stress protocol, or clinical data using a 17-segment model and 5-point scoring system. A summed stress score (SSS), summed rest score (SRS), and summed difference (SSS-SRS) score (SDS) were calculated for each image. Peak stress heart rate and rate-pressure product were higher for adenosine-exercise than adenosine (102 ± 19 vs 81 ± 11 beats/min and 13,972 ± 4,265 vs 10,623 ± 2,131, respectively; both p <0.001). Sensitivity for detection of ≥50% coronary stenosis was 75% and 72% for adenosine-exercise and adenosine, respectively (p = NS). There were no differences in SSS and SDS between adenosine-exercise and adenosine (8.2 ± 5.9 vs 8.1 ± 6.3 and 4.9 ± 4.1 vs 5.2 ± 4.6, respectively; both p = NS). Thus, in patients with coronary artery disease, limited treadmill exercise combined with adenosine does not increase myocardial perfusion defect severity compared with standard adenosine technetium-99m sestamibi single-photon emission computed tomographic myocardial perfusion imaging
Acute beta-blockade reduces the extent and severity of myocardial perfusion defects with dipyridamole Tc-99m sestamibi SPECT imaging
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