We reconstruct crustal structure along the Lesser Antilles island arc using an inversion approach combining constraints from petrology of magmatic crustal xenoliths and seismic receiver functions. ...Xenoliths show considerable island-to-island variation in xenolith petrology from plagioclase-free ultramafic lithologies to gabbros and gabbronorites with variable proportions of amphibole, indicative of changing magma differentiation depths. Xenoliths represent predominantly cumulate compositions with equilibration depths in the range 5 to 40 km. We use xenolith mineral modes and compositions to calculate seismic velocities (vP,vS) and density at the estimated equilibration depths. We create a five-layer model of crustal structure for testing against receiver functions (RF) from island seismic stations along the arc. Lowermost layer (5) comprises peridotite with physical characteristics of mantle xenoliths from Grenada. Uppermost layer (1) consists of 5 km of volcaniclastics and sediments, whose physical properties are determined via a grid inversion routine. The three middle layers (2) to (4) comprise igneous arc crust with compositions corresponding to the xenoliths sampled at each island. By inversion we obtain a petrological best-fit for the RF on each island to establish the nature and thicknesses of layers (2) to (4).
Along the arc we see variations in the depth and strength of both Moho and mid-crustal discontinuity (MCD) on length-scales of tens of km. Moho depths vary from 25 to 37 km; MCD from 11 and 32 km. The Moho is the dominant discontinuity beneath some islands (St. Kitts, Guadeloupe, Martinique, Grenada), whereas the MCD dominates beneath others (Saba, St. Eustatius). Along-arc variability in MCD depth and strength is consistent with variation in estimated magmatic H2O contents and differentiations depths that, in turn, influence xenolith lithologies. A striking feature is steep, along-arc gradients in vP similar to those observed at other oceanic arcs. These gradients reflect abrupt changes in rates and processes of magma generation in the underlying crust and mantle. We find no evidence for large, interconnected bodies of partial melt beneath the Lesser Antilles. Instead, the crustal velocity structure is consistent with magma differentiation in vertically-extensive, crystal mush-dominated reservoirs. Along-arc variation in crustal structure may reflect heterogeneous upwelling within the mantle wedge, itself driven by variation in slab-derived H2O fluxes.
•Arc crustal structure modelled by integrating petrology of 230 igneous xenoliths with seismic data from 23 islands.•Crust comprises four layers defined on basis of xenolith composition, calculated seismic properties and receiver functions.•Steep lateral velocity gradients and irregular along-arc variations in depth to Moho and mid-crustal discontinuity.•Lateral variation consistent with island-to-island variation in xenolith petrology.•Velocity structure reflects heterogeneous upwelling within the mantle wedge, driven by variation in slab-derived H2O fluxes.
Near-patient testing (NPT) allows clinical decisions to be made in a rapid and convenient manner and is often cost effective. In COPD the peripheral blood eosinophil count has been demonstrated to ...have utility in providing prognostic information and predicting response to treatment during an acute exacerbation. For this potential to be achieved having a reliable NPT of blood eosinophil count would be extremely useful. Therefore, we investigated the use of the HemoCue
WBC Diff System and evaluated its sensitivity and specificity in healthy, asthmatic and COPD subjects. This method requires a simple skin prick of blood and was compared to standard venepuncture laboratory analysis. The HemoCue
WBC Diff System measured the peripheral blood eosinophil count in healthy, asthma and COPD subjects with very close correlation to the eosinophil count as measured by standard venepuncture. The correlations were unaffected by disease status. This method for the measurement of the peripheral blood eosinophil count has the potential to provide rapid near-patient results and thus influence the speed of management decisions in the treatment of airway diseases.
Previous metagenomic studies in asthma have been limited by inadequate sequencing depth for species-level bacterial identification and by heterogeneity in clinical phenotyping. We hypothesize that ...chronic bacterial airways infection is a key "treatable trait" whose prevalence, clinical phenotype and reliable biomarkers need definition. In this study, we have applied a method for Oxford Nanopore sequencing for the unbiased metagenomic characterization of severe asthma. We optimized methods to compare performance of Illumina MiSeq, Nanopore sequencing, and RT-qPCR on total sputum DNA extracts against culture/MALDI-TOF for analysis of induced sputum samples from highly phenotyped severe asthma during clinical stability. In participants with severe asthma (
= 23) H. influenzae was commonly cultured (
= 8) and identified as the dominant bacterial species by metagenomic sequencing using an optimized method for Illumina MiSeq and Oxford Nanopore. Alongside superior operational characteristics, Oxford Nanopore achieved near complete genome coverage of H. influenzae and demonstrated a high level of agreement with Illumina MiSeq data. Clinically significant infection was confirmed with validated H. influenzae plasmid-based quantitative PCR assay. H. influenzae positive patients were found to have sputum neutrophilia and lower FeNO. In conclusion, using an optimized method of direct sequencing of induced sputum samples, H. influenzae was identified as a clinically relevant pathogen in severe asthma and was identified reliably using metagenomic sequencing. Application of these protocols in ongoing analysis of large patient cohorts will allow full characterization of this clinical phenotype.
The human airways were once thought sterile in health. Now metagenomic techniques suggest bacteria may be present, but their role in asthma is not understood. Traditional culture lacks sensitivity and current sequencing techniques are limited by operational problems and limited ability to identify pathogens at species level. We optimized a new sequencing technique-Oxford Nanopore technologies (ONT)-for use on human sputum samples and compared it with existing methods. We found ONT was effective for rapidly analyzing samples and could identify bacteria at the species level. We used this to show Haemophilus influenzae was a dominant bacterium in the airways in people with severe asthma. The presence of Haemophilus was associated with a "neutrophilic" form of asthma - a subgroup for which we currently lack specific treatments. Therefore, this technique could be used to target chronic antibiotic therapy and in research to characterize the full breadth of bacteria in the airways.
Purpose
The purpose of this study was to capture the experience of people after completing their period of COVID-19 14-day isolation in prison. This study used in-depth interviews to assess the ...impact of the restricted regime.
Design/methodology/approach
This was a cross-sectional qualitative study using an adapted regional survey to record people’s experiences of COVID-19 isolation on entry into prison. This study began in April 2020 and continued to run over eight months. A weekly capture of people’s stories was conducted using a convenience sample. A total of 168 people participated in the study, with in-depth interviews conducted by the health-care team. Content conceptual analysis was used to quantify and analyse the themes of impact of COVID-19 isolation. This information was then used to shape iterative health-care service development.
Findings
A number of key themes have emerged from the experiences of COVID-19 isolation, including connection, communication and support. Stories highlighted how isolation had exacerbated depression, anxiety or feelings of self-harm. This was amplified by the uncertainty of the pandemic and lack of information about accessing services in the altered prison regime. A priority for people in COVID-19 isolation was contact with family. Telephone calls and virtual visits were cited as mitigating the mental health impact of social isolation. People who felt supported by health-care or prison staff reported coping with their time in isolation better. Timely, accessible information was pivotal in support, leading to development of Engagement Lead check-ins on the isolation landings. It is crucial that a public health approach is core to the COVID-19 response in prisons. The thematic analysis of the experiences has enabled a focused understanding of the impact of COVID-19 isolation and an accountability of care provision through organisational collaboration and iterative improvements to service delivery.
Originality/value
There is a paucity of real-time evidence of the impact of restricted regimes in prison owing to COVID-19. This study gives an important insight.
Asthma in pregnancy: An update Couillard, Simon; Connolly, Clare; Borg, Catherine ...
Obstetric Medicine,
09/2021, Letnik:
14, Številka:
3
Book Review, Journal Article
Recenzirano
Odprti dostop
Aim
To update obstetric care providers about asthma management.
Summary
Asthma is the most frequent comorbid chronic illness in pregnancy. Convincing evidence shows that uncontrolled asthma magnifies ...the risk of maternal, fetal and neonate complications. Unfortunately, one in four women take no inhaler during pregnancy, and it is likely that decreased adherence, rather than changes in pathology, explains uncontrolled maternal asthma. Patient surveys reveal a need for information and reassurance. Although some molecules are preferred in pregnancy, there is currently no basis to withhold any asthma medication – old or new. Biomarkers such as blood eosinophils and fractional exhaled nitric oxide are an effective way to assess the risk of asthma attacks and the likelihood of responding to inhaled steroids. Furthermore, practice-changing trials in mild asthma show that switching reliever-only regimens to as-needed ‘controller-and-reliever’ therapy is effective. We suggest that applying these changes can alleviate women’s concerns and improve outcomes.
PDF
