476 research outputs found
Linear growth in preschool children treated with mass azithromycin distributions for trachoma: A cluster-randomized trial.
BackgroundMass azithromycin distributions have been shown to reduce mortality among pre-school children in sub-Saharan Africa. It is unclear what mediates this mortality reduction, but one possibility is that antibiotics function as growth promoters for young children.Methods and findings24 rural Ethiopian communities that had received biannual mass azithromycin distributions over the previous four years were enrolled in a parallel-group, cluster-randomized trial. Communities were randomized in a 1:1 ratio to either continuation of biannual oral azithromycin (20mg/kg for children, 1 g for adults) or to no programmatic antibiotics over the 36 months of the study period. All community members 6 months and older were eligible for the intervention. The primary outcome was ocular chlamydia; height and weight were measured as secondary outcomes on children less than 60 months of age at months 12 and 36. Study participants were not masked; anthropometrists were not informed of the treatment allocation. Anthropometric measurements were collected for 282 children aged 0-36 months at the month 12 assessment and 455 children aged 0-59 months at the month 36 assessment, including 207 children who had measurements at both time points. After adjusting for age and sex, children were slightly but not significantly taller in the biannually treated communities (84.0 cm, 95%CI 83.2-84.8, in the azithromycin-treated communities vs. 83.7 cm, 95%CI 82.9-84.5, in the untreated communities; mean difference 0.31 cm, 95%CI -0.85 to 1.47, P = 0.60). No adverse events were reported.ConclusionsPeriodic mass azithromycin distributions for trachoma did not demonstrate a strong impact on childhood growth.Trial registrationThe TANA II trial was registered on clinicaltrials.gov #NCT01202331
N-terminal substitutions in HIV-1 gp41 reduce the expression of non-trimeric envelope glycoproteins on the virus
AbstractThe native, functional HIV-1 envelope glycoprotein (Env) complex is a trimer of two non-covalently associated subunits: the gp120 surface glycoprotein and the gp41 transmembrane glycoprotein. However, various non-functional forms of Env are present on virus particles and HIV-1-infected cells, some of which probably arise as the native complex decays. The aberrant forms include gp120–gp41 monomers and oligomers, as well as gp41 subunits from which gp120 has dissociated. The presence of non-functional Env creates binding sites for antibodies that do not recognize native Env complexes and that are, therefore, non-neutralizing. Non-native Env forms (monomers, dimers, tetramers and aggregates) can also arise when soluble gp140 proteins, lacking the cytoplasmic and transmembrane domains of gp41, are expressed for vaccine studies. We recently identified five amino acids in the gp41 N-terminal region (I535, Q543, S553, K567 and R588) that promote gp140 trimerization. We have now studied their influence on the function and antigenic properties of JR-FL Env expressed on the surfaces of pseudoviruses and Env-transfected cells. The 5 substitutions in gp41 reduce the expression of non-trimeric gp160s, without affecting trimer levels. Pseudovirions bearing the mutant Env are fully infectious with similar kinetics of Env-mediated fusion. Various non-neutralizing antibodies bind less strongly to the Env mutant, but neutralizing antibody binding is unaffected. Hence the gp41 substitutions do not adversely affect Env structure, supporting their use for making new Env-based vaccines. The mutant Env might also help in studies intended to correlate antibody binding to virus neutralization. Of note is that the 5 residues are much more frequent, individually or collectively, in viruses from subtypes other than B
The efficacy of oral azithromycin in clearing ocular chlamydia: mathematical modeling from a community-randomized trachoma trial.
Mass oral azithromycin distributions have dramatically reduced the prevalence of the ocular strains of chlamydia that cause trachoma. Assessing efficacy of the antibiotic in an individual is important in planning trachoma elimination. However, the efficacy is difficult to estimate, because post-treatment laboratory testing may be complicated by nonviable organisms or reinfection. Here, we monitored ocular chlamydial infection twice a year in pre-school children in 32 communities as part of a cluster-randomized clinical trial in Tanzania (prevalence in children was lowered from 22.0% to 4.7% after 3-year of annual treatment). We used a mathematical transmission model to estimate the prevalence of infection immediately after treatment, and found the effective field efficacy of antibiotic in an individual to be 67.6% (95% CI: 56.5-75.1%) in this setting. Sensitivity analyses suggested that these results were not dependent on specific assumptions about the duration of infection. We found no evidence of decreased efficacy during the course of the trial. We estimated an 89% chance of elimination after 10 years of annual treatment with 95% coverage
Investigating the effects of mobile bottom fishing on benthic biota:A systematic review protocol
Background Mobile bottom fishing, such as trawling and dredging, is the most widespread direct human impact on marine benthic systems. Knowledge of the impacts of different gear types on different habitats, the species most sensitive to impacts and the potential for habitats to recover are often needed to inform implementation of an ecosystem approach to fisheries and strategies for biodiversity conservation. This knowledge helps to identify management options that maximise fisheries yield whilst minimising negative impacts on benthic systems. Methods/design The methods are designed to identify and collate evidence from experimental studies (e.g. before/after, control/impact) and comparative studies (spanning a gradient of fishing intensity) to identify changes in state (numbers, biomass, diversity etc.) of benthic biota (flora and fauna), resulting from a variety of mobile bottom fishing scenarios. The primary research question that the outputs will be used to address is: “to what extent does a given intensity of bottom fishing affect the abundance and/or diversity of benthic biota?” Due to the variety of gear and habitat types studied, the primary question will be closely linked with secondary questions. These include: “how does the effect of bottom fishing on various benthic biota metrics (species, faunal type, trait, taxon etc.) vary with (1) gear type and (2) habitat, and (3) gear type-habitat interactions?” and (4) “how might properties of the community and environment affect the resilience (and recovery potential) of a community to bottom fishing?
Rac1 as a therapeutic target in ovarian cancer
Rac1 is a high value therapeutic target for cancer based on its tumor promoting activities, yet clinical applications targeting Rac1 are in their infancy. High expression and hyperactivation of Rac1 in ovarian cancer, along with our identification of R-ketorolac as a novel Rac1 and Cdc42 selective inhibitor with translational potential, prompt us to test the hypothesis that targeting Rac1 has therapeutic utility for ovarian cancer. Ascites tumor cell samples from ovarian cancer patients in a prospective study receiving racemic ketorolac for clinically indicated use in pain relief were previously reported to show time dependent reduction of Rac1 and Cdc42 activities post-treatment. New RNA seq data of these patient samples reveals significant changes of genes involved in cell adhesion, cytokine-mediated signaling and cytokine production pathways. Conversely, the identified downregulated genes were overexpressed and associated with worse survival in ovarian cancer patients analyzed through The Cancer Genome Atlas (TCGA). Among the downregulated genes in the NOD pathway are chemokines and pro-inflammatory cytokines. Follow-up cytokine panels from patients confirm that racemic ketorolac treatment reduces the levels of immunosuppressive cytokines IL-6, IL-10 and RANTES in ascites fluids. Together, these data indicate there may be a benefit to the anti-inflammatory activity of the S- enantiomer, as well as the GTPase inhibitory activity of the R- enantiomer of ketorolac for ovarian cancer treatment
Photonic crystal Microarray Nanoplatform for High Throughput Detection of Biomolecules
ABSTRACT We present preliminary designs and experimental results for creating a microarray nanoplatform based on twodimensional photonic crystal devices in silicon. Multiple photonic crystal microcavities are coupled along the length of a single photonic crystal waveguide that undergo resonance wavelength shifts when an antibody-antibody binding event occurs in the immediate vicinity of the corresponding photonic crystal microcavity. The microarray nanoplatform enables high throughput measurements of multiple antibody-antibody interactions via a single optical waveguide transmission measurement
Who participates in web-assisted tobacco interventions? The quit-primo and national dental practice-based research network hi-quit studies
INTRODUCTION: Smoking is the most preventable cause of death. Although effective, Web-assisted tobacco interventions are underutilized and recruitment is challenging. Understanding who participates in Web-assisted tobacco interventions may help in improving recruitment.
OBJECTIVES: To understand characteristics of smokers participating in a Web-assisted tobacco intervention (Decide2Quit.org).
METHODS: In addition to the typical Google advertisements, we expanded Decide2Quit.org recruitment to include referrals from medical and dental providers. We assessed how the expanded recruitment of smokers changed the users\u27 characteristics, including comparison with a population-based sample of smokers from the national Behavioral Risk Factors Surveillance Survey (BRFSS). Using a negative binomial regression, we compared demographic and smoking characteristics by recruitment source, in particular readiness to quit and association with subsequent Decide2Quit.org use.
RESULTS: The Decide2Quit.org cohort included 605 smokers; the 2010 BRFSS dataset included 69,992. Compared to BRFSS smokers, a higher proportion of Decide2Quit.org smokers were female (65.2% vs 45.7%, P=.001), over age 35 (80.8% vs 67.0%, P=.001), and had some college or were college graduates (65.7% vs 45.9%, P=.001). Demographic and smoking characteristics varied by recruitment; for example, a lower proportion of medical- (22.1%) and dental-referred (18.9%) smokers had set a quit date or had already quit than Google smokers (40.1%, P
CONCLUSIONS: Recruitment from clinical practices complimented Google recruitment attracting smokers less motivated to quit and less experienced with Web-assisted tobacco interventions.
TRIAL REGISTRATION: Clinicaltrials.gov NCT00797628; http://clinicaltrials.gov/ct2/show/NCT00797628 (Archived by WebCite at http://www.webcitation.org/6F3tqz0b3)
Estimating the sustainability of towed fishing-gear impacts on seabed habitats: a simple quantitative risk assessment method applicable to data-limited fisheries
1. Impacts of bottom fishing, particularly trawling and dredging, on seabed (benthic) habitats are commonly perceived to pose serious environmental risks. Quantitative ecological risk assessment can be used to evaluate actual risks and to help guide the choice of management measures needed to meet sustainability objectives. 2. We develop and apply a quantitative method for assessing the risks to benthic habitats by towed bottom-fishing gears. The method is based on a simple equation for relative benthic status (RBS), derived by solving the logistic population growth equation for the equilibrium state. Estimating RBS requires only maps of fishing intensity and habitat type — and parameters for impact and recovery rates, which may be taken from meta-analyses of multiple experimental studies of towed-gear impacts. The aggregate status of habitats in an assessed region is indicated by the distribution of RBS values for the region. The application of RBS is illustrated for a tropical shrimp-trawl fishery. 3. The status of trawled habitats and their RBS value depend on impact rate (depletion per trawl), recovery rate and exposure to trawling. In the shrimp-trawl fishery region, gravel habitat was most sensitive, and though less exposed than sand or muddy-sand, was most affected overall (regional RBS=91% relative to un-trawled RBS=100%). Muddy-sand was less sensitive, and though relatively most exposed, was less affected overall (RBS=95%). Sand was most heavily trawled but least sensitive and least affected overall (RBS=98%). Region-wide, >94% of habitat area had >80% RBS because most trawling and impacts were confined to small areas. RBS was also applied to the region's benthic invertebrate communities with similar results. 4. Conclusions. Unlike qualitative or categorical trait-based risk assessments, the RBS method provides a quantitative estimate of status relative to an unimpacted baseline, with minimal requirements for input data. It could be applied to bottom-contact fisheries worldwide, including situations where detailed data on characteristics of seabed habitats, or the abundance of seabed fauna are not available. The approach supports assessment against sustainability criteria and evaluation of alternative management strategies (e.g. closed areas, effort management, gear modifications)
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Impact of stratospheric air and surface emissions on tropospheric nitrous oxide during ATom
We measured the global distribution of tropospheric N2O mixing ratios during the NASA airborne Atmospheric Tomography (ATom) mission. ATom measured concentrations of ∼ 300 gas species and aerosol properties in 647 vertical profiles spanning the Pacific, Atlantic, Arctic, and much of the Southern Ocean basins, nearly from pole to pole, over four seasons (2016–2018). We measured N2O concentrations at 1 Hz using a quantum cascade laser spectrometer (QCLS). We introduced a new spectral retrieval method to account for the pressure and temperature sensitivity of the instrument when deployed on aircraft. This retrieval strategy improved the precision of our ATom QCLS N2O measurements by a factor of three (based on the standard deviation of calibration measurements). Our measurements show that most of the variance of N2O mixing ratios in the troposphere is driven by the influence of N2O-depleted stratospheric air, especially at mid- and high latitudes. We observe the downward propagation of lower N2O mixing ratios (compared to surface stations) that tracks the influence of stratosphere–troposphere exchange through the tropospheric column down to the surface. The highest N2O mixing ratios occur close to the Equator, extending through the boundary layer and free troposphere. We observed influences from a complex and diverse mixture of N2O sources, with emission source types identified using the rich suite of chemical species measured on ATom and the geographical origin calculated using an atmospheric transport model. Although ATom flights were mostly over the oceans, the most prominent N2O enhancements were associated with anthropogenic emissions, including from industry (e.g., oil and gas), urban sources, and biomass burning, especially in the tropical Atlantic outflow from Africa. Enhanced N2O mixing ratios are mostly associated with pollution-related tracers arriving from the coastal area of Nigeria. Peaks of N2O are often associated with indicators of photochemical processing, suggesting possible unexpected source processes. In most cases, the results show how difficult it is to separate the mixture of different sources in the atmosphere, which may contribute to uncertainties in the N2O global budget. The extensive data set from ATom will help improve the understanding of N2O emission processes and their representation in global models.
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Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set
When galaxies merge, the supermassive black holes in their centers may form
binaries and, during the process of merger, emit low-frequency gravitational
radiation in the process. In this paper we consider the galaxy 3C66B, which was
used as the target of the first multi-messenger search for gravitational waves.
Due to the observed periodicities present in the photometric and astrometric
data of the source of the source, it has been theorized to contain a
supermassive black hole binary. Its apparent 1.05-year orbital period would
place the gravitational wave emission directly in the pulsar timing band. Since
the first pulsar timing array study of 3C66B, revised models of the source have
been published, and timing array sensitivities and techniques have improved
dramatically. With these advances, we further constrain the chirp mass of the
potential supermassive black hole binary in 3C66B to less than using data from the NANOGrav 11-year data set. This
upper limit provides a factor of 1.6 improvement over previous limits, and a
factor of 4.3 over the first search done. Nevertheless, the most recent orbital
model for the source is still consistent with our limit from pulsar timing
array data. In addition, we are able to quantify the improvement made by the
inclusion of source properties gleaned from electromagnetic data to `blind'
pulsar timing array searches. With these methods, it is apparent that it is not
necessary to obtain exact a priori knowledge of the period of a binary to gain
meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap
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