352 research outputs found
Tree Fern Apical Temperatures at the Royal Botanic Garden Edinburgh
Tree ferns are difficult to maintain out of doors in the British Isles except in western localities, where winter temperatures are moderated by the North Atlantic Drift, or in places where buildings provide a clement microclimate. The present study of tree-fern apical temperatures during winter was carried out on five trunked specimens of Dicksonia antarctica that had been grown satisfactorily out of doors for several years, while planted in the ground of a courtyard at the Royal Botanic Garden Edinburgh (RBGE). The plants were never wrapped or otherwise protected with thermal insulation during the winter months. An electric thermometer was inserted into the apical cleft of each plant in November 2003, and weekly readings of minimum and maximum temperature taken until April 2004. The ambient temperature of the air in the courtyard was similarly recorded and compared with the screen and grass temperatures at the RBGE weather station in the main botanic garden.
The lowest grass and screen temperatures were respectively -11.2°C and -7.1°C, whereas the lowest courtyard and fern-apical temperatures were respectively -3.2°C and -0.8°C. Thus in the coldest period of that winter there was over 10°C difference in temperature between ground level in the main garden and a tree fern apical cleft in the sheltered courtyard.
The tree ferns were not noticeably damaged by exposure of the apical cleft region to just below freezing point on a few occasions and the fronds stayed green. The five individual plants differed considerably in trunk height, diameter and volume. Regression analysis revealed that there was a significantly increasing thermal-insulating effect in the apical cleft associated with larger trunk diameters and volumes.
The RBGE weather station temperatures during the winter of 2003-4 were unexceptional when compared with records from the previous 19 years. Thus the data from 2003-4 may be taken as representing a typical recent winter for this Edinburgh location.
This study highlights the benefits of having detailed temperature measurements when assessing the winter-protective capabilities of a particular micro—environment for a semi-hardy species such as D. antarctica
Immune response modifiers in the treatment of asthma: A PRACTALL document of the American Academy of Allergy, Asthma & Immunology and the European Academy of Allergy and Clinical Immunology
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Mechanical thrombectomy in patients with acute ischemic stroke: a cost-effectiveness and value of implementation analysis
Background:
Recent clinical trials have demonstrated the efficacy of mechanical thrombectomy in acute ischemic stroke.
Aims:
To determine the cost-effectiveness, value of future research, and value of implementation of mechanical thrombectomy.
Methods:
Using UK clinical and cost data from the Pragmatic Ischemic Stroke Thrombectomy Evaluation (PISTE) trial, we estimated the cost-effectiveness of mechanical thrombectomy over time horizons of 90-days and lifetime, based on a decision-analytic model, using all existing evidence. We performed a meta-analysis of seven clinical trials to estimate treatment effects. We used sensitivity analysis to address uncertainty. Value of implementation analysis was used to estimate the potential value of additional implementation activities to support routine delivery of mechanical thrombectomy.
Results:
Over the trial period (90 days), compared with best medical care alone, mechanical thrombectomy incurred an incremental cost of £5207 and 0.025 gain in QALY (incremental cost-effectiveness ratio (ICER) £205,279), which would not be considered cost-effective. However, mechanical thrombectomy was shown to be cost-effective over a lifetime horizon, with an ICER of £3466 per QALY gained. The expected value of perfect information per patient eligible for mechanical thrombectomy in the UK is estimated at £3178. The expected value of full implementation of mechanical thrombectomy is estimated at £1.3 billion over five years.
Conclusion:
Mechanical thrombectomy was cost-effective compared with best medical care alone over a patient’s lifetime. On the assumption of 30% implementation being achieved throughout the UK healthcare system, we estimate that the population health benefits obtained from this treatment are greater than the cost of implementation.
Trial registration:
NCT01745692
A Large Web-Based Observer Reliability Study of Early Ischaemic Signs on Computed Tomography. The Acute Cerebral CT Evaluation of Stroke Study (ACCESS)
BACKGROUND: Early signs of ischaemic stroke on computerised tomography (CT) scanning are subtle but CT is the most widely available diagnostic test for stroke. Scoring methods that code for the extent of brain ischaemia may improve stroke diagnosis and quantification of the impact of ischaemia. METHODOLOGY AND PRINCIPAL FINDINGS: We showed CT scans from patients with acute ischaemic stroke (n = 32, with different patient characteristics and ischaemia signs) to doctors in stroke-related specialties world-wide over the web. CT scans were shown twice, randomly and blindly. Observers entered their scan readings, including early ischaemic signs by three scoring methods, into the web database. We compared observers' scorings to a reference standard neuroradiologist using area under receiver operator characteristic curve (AUC) analysis, Cronbach's alpha and logistic regression to determine the effect of scales, patient, scan and observer variables on detection of early ischaemic changes. Amongst 258 readers representing 33 nationalities and six specialties, the AUCs comparing readers with the reference standard detection of ischaemic signs were similar for all scales and both occasions. Being a neuroradiologist, slower scan reading, more pronounced ischaemic signs and later time to CT all improved detection of early ischaemic signs and agreement on the rating scales. Scan quality, stroke severity and number of years of training did not affect agreement. CONCLUSIONS: Large-scale observer reliability studies are possible using web-based tools and inform routine practice. Slower scan reading and use of CT infarct rating scales improve detection of acute ischaemic signs and should be encouraged to improve stroke diagnosis
PLAUR polymorphisms and lung function in UK smokers
<p>Abstract</p> <p>Background</p> <p>We have previously identified Urokinase Plasminogen Activator Receptor (<it>PLAUR</it>) as an asthma susceptibility gene. In the current study we tested the hypothesis that <it>PLAUR </it>single nucleotide polymorphisms (SNPs) determine baseline lung function and contribute to the development of Chronic Obstructive Pulmonary Disease (COPD) in smokers.</p> <p>Methods</p> <p>25 <it>PLAUR </it>SNPs were genotyped in COPD subjects and individuals with smoking history (n = 992). Linear regression was used to determine the effects of polymorphism on baseline lung function (FEV<sub>1</sub>, FEV<sub>1</sub>/FVC) in all smokers. Genotype frequencies were compared in spirometry defined smoking controls (n = 176) versus COPD cases (n = 599) and COPD severity (GOLD stratification) using logistic regression.</p> <p>Results</p> <p>Five SNPs showed a significant association (p < 0.01) with baseline lung function; rs2302524(Lys220Arg) and rs2283628(intron 3) were associated with lower and higher FEV<sub>1 </sub>respectively. rs740587(-22346), rs11668247(-20040) and rs344779(-3666) in the 5'region were associated with increased FEV<sub>1</sub>/FVC ratio. rs740587 was also protective for COPD susceptibility and rs11668247 was protective for COPD severity although no allele dose relationship was apparent. Interestingly, several of these associations were driven by male smokers not females.</p> <p>Conclusion</p> <p>This study provides tentative evidence that the asthma associated gene <it>PLAUR </it>also influences baseline lung function in smokers. However the case-control analyses do not support the conclusion that <it>PLAUR </it>is a major COPD susceptibility gene in smokers. PLAUR is a key serine protease receptor involved in the generation of plasmin and has been implicated in airway remodelling.</p
Measuring axial length of the eye from magnetic resonance brain imaging
BACKGROUND: Metrics derived from the human eye are increasingly used as biomarkers and endpoints in studies of cardiovascular, cerebrovascular and neurological disease. In this context, it is important to account for potential confounding that can arise from differences in ocular dimensions between individuals, for example, differences in globe size. METHODS: We measured axial length, a geometric parameter describing eye size from T(2)-weighted brain MRI scans using three different image analysis software packages (Mango, ITK and Carestream) and compared results to biometry measurements from a specialized ophthalmic instrument (IOLMaster 500) as the reference standard. RESULTS: Ninety-three healthy research participants of mean age 51.0 ± SD 5.4 years were analyzed. The level of agreement between the MRI-derived measurements and the reference standard was described by mean differences as follows, Mango − 0.8 mm; ITK − 0.5 mm; and Carestream − 0.1 mm (upper/lower 95% limits of agreement across the three tools ranged from 0.9 mm to − 2.6 mm). Inter-rater reproducibility was between − 0.03 mm and 0.45 mm (ICC 0.65 to 0.93). Intra-rater repeatability was between 0.0 mm and − 0.2 mm (ICC 0.90 to 0.95). CONCLUSIONS: We demonstrate that axial measurements of the eye derived from brain MRI are within 3.5% of the reference standard globe length of 24.1 mm. However, the limits of agreement could be considered clinically significant. Axial length of the eye obtained from MRI is not a replacement for the precision of biometry, but in the absence of biometry it could provide sufficient accuracy to act as a proxy. We recommend measuring eye axial length from MRI in studies that do not have biometry but use retinal imaging to study neurodegenerative changes so as to control for differing eye size across individuals. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12886-022-02289-y
Quantitative analysis of high-resolution computed tomography scans in severe asthma subphenotypes
BACKGROUND: Severe asthma is a heterogeneous condition. Airway remodelling is a feature of severe asthma and can be determined by the assessment of high-resolution computed tomography (HRCT) scans. The aim of this study was to assess whether airway remodelling is restricted to specific subphenotypes of severe asthma. METHODS: A retrospective analysis was performed of HRCT scans from subjects who had attended a single-centre severe asthma clinic between 2003 and 2008. The right upper lobe apical segmental bronchus (RB1) dimensions were measured and the clinical and sputum inflammatory characteristics associated with RB1 geometry were assessed by univariate and multivariate regression analyses. Longitudinal sputum data were available and were described as area under the time curve (AUC). Comparisons were made in RB1 geometry across subjects in four subphenotypes determined by cluster analysis, smokers and non-smokers, and subjects with and without persistent airflow obstruction. RESULTS: Ninety-nine subjects with severe asthma and 16 healthy controls were recruited. In the subjects with severe asthma the RB1 percentage wall area (%WA) was increased (p=0.009) and lumen area (LA)/body surface area (BSA) was decreased (p=0.008) compared with controls but was not different across the four subphenotypes. Airway geometry was not different between smokers and non-smokers and RB1 %WA was increased in those with persistent airflow obstruction. RB1 %WA in severe asthma was best associated with airflow limitation and persistent neutrophilic airway inflammation (model R(2)=0.27, p=0.001). CONCLUSIONS: Airway remodelling of proximal airways occurs in severe asthma and is associated with impaired lung function and neutrophilic airway inflammation
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