15,714 research outputs found
White matter lesions characterise brain involvement in moderate to severe chronic obstructive pulmonary disease, but cerebral atrophy does not.
BACKGROUND: Brain pathology is relatively unexplored in chronic obstructive pulmonary disease (COPD). This study is a comprehensive investigation of grey matter (GM) and white matter (WM) changes and how these relate to disease severity and cognitive function. METHODS: T1-weighted and fluid-attenuated inversion recovery images were acquired for 31 stable COPD patients (FEV1 52.1% pred., PaO2 10.1 kPa) and 24 age, gender-matched controls. T1-weighted images were segmented into GM, WM and cerebrospinal fluid (CSF) tissue classes using a semi-automated procedure optimised for use with this cohort. This procedure allows, cohort-specific anatomical features to be captured, white matter lesions (WMLs) to be identified and includes a tissue repair step to correct for misclassification caused by WMLs. Tissue volumes and cortical thickness were calculated from the resulting segmentations. Additionally, a fully-automated pipeline was used to calculate localised cortical surface and gyrification. WM and GM tissue volumes, the tissue volume ratio (indicator of atrophy), average cortical thickness, and the number, size, and volume of white matter lesions (WMLs) were analysed across the whole-brain and regionally - for each anatomical lobe and the deep-GM. The hippocampus was investigated as a region-of-interest. Localised (voxel-wise and vertex-wise) variations in cortical gyrification, GM density and cortical thickness, were also investigated. Statistical models controlling for age and gender were used to test for between-group differences and within-group correlations. Robust statistical approaches ensured the family-wise error rate was controlled in regional and local analyses. RESULTS: There were no significant differences in global, regional, or local measures of GM between patients and controls, however, patients had an increased volume (p = 0.02) and size (p = 0.04) of WMLs. In patients, greater normalised hippocampal volume positively correlated with exacerbation frequency (p = 0.04), and greater WML volume was associated with worse episodic memory (p = 0.05). A negative relationship between WML and FEV1 % pred. approached significance (p = 0.06). CONCLUSIONS: There was no evidence of cerebral atrophy within this cohort of stable COPD patients, with moderate airflow obstruction. However, there were indications of WM damage consistent with an ischaemic pathology. It cannot be concluded whether this represents a specific COPD, or smoking-related, effect
Recommended from our members
Trump-induced anxiety among Latina/os
During the 2016 election, Donald Trump castigated unauthorized immigrants as “murderers and rapists.” During his presidency, he continued the use of this rhetoric, explicitly linking unauthorized migrants to threatening narratives. Here, we consider three questions: Did Donald Trump and his immigration positions serve as an “anxiety trigger” for Latina/os? Are individuals with contextually stigmatized attributes especially sensitive to Trump and his policy proposals? Is Spanish language itself, an attribute negatively stigmatized in the context of the immigration issue, sufficient to increase deportation anxiety? Utilizing survey experiments of Latina/os, we demonstrate that exposure to a Trump immigration cue is sufficient to increase anxiety about deportation. We also demonstrate that stigmatized attributes predict anxiety, but do not moderate the effect of the Trump cue. Lastly, we provide evidence that survey language affects anxiety among Latina/os. In Studies 1 (n = 736) and 2 (n = 1,040), we show that exposure to information about Trump’s immigration agenda significantly increases reports about deportation anxiety. In Study 3 (n = 1,734), we show that the Trump exposure condition induces heightened anxiety but that Latina/o attributes (language proficiency and use, immigration status, assessed phenotype) and identity strength have an independent effect on deportation anxiety. In Study 4 (n = 775), we randomized bilingual respondents into Spanish or English language survey protocols and found that comparable bilinguals exposed to Spanish language report higher levels of anxiety compared to English-language survey takers
Recommended from our members
Disruption of white matter connectivity in chronic obstructive pulmonary disease.
BACKGROUND: Mild cognitive impairment is a common systemic manifestation of chronic obstructive pulmonary disease (COPD). However, its pathophysiological origins are not understood. Since, cognitive function relies on efficient communication between distributed cortical and subcortical regions, we investigated whether people with COPD have disruption in white matter connectivity. METHODS: Structural networks were constructed for 30 COPD patients (aged 54-84 years, 57% male, FEV1 52.5% pred.) and 23 controls (aged 51-81 years, 48% Male). Networks comprised 90 grey matter regions (nodes) interconnected by white mater fibre tracts traced using deterministic tractography (edges). Edges were weighted by the number of streamlines adjusted for a) streamline length and b) end-node volume. White matter connectivity was quantified using global and nodal graph metrics which characterised the networks connection density, connection strength, segregation, integration, nodal influence and small-worldness. Between-group differences in white matter connectivity and within-group associations with cognitive function and disease severity were tested. RESULTS: COPD patients' brain networks had significantly lower global connection strength (p = 0.03) and connection density (p = 0.04). There was a trend towards COPD patients having a reduction in nodal connection density and connection strength across the majority of network nodes but this only reached significance for connection density in the right superior temporal gyrus (p = 0.02) and did not survive correction for end-node volume. There were no other significant global or nodal network differences or within-group associations with disease severity or cognitive function. CONCLUSION: COPD brain networks show evidence of damage compared to controls with a reduced number and strength of connections. This loss of connectivity was not sufficient to disrupt the overall efficiency of network organisation, suggesting that it has redundant capacity that makes it resilient to damage, which may explain why cognitive dysfunction is not severe. This might also explain why no direct relationships could be found with cognitive measures. Smoking and hypertension are known to have deleterious effects on the brain. These confounding effects could not be excluded
Simple non-mydriatic retinal photography is feasible and demonstrates retinal microvascular dilation in Chronic Obstructive Pulmonary Disease (COPD).
BACKGROUND: Chronic Obstructive Pulmonary Disease (COPD) is associated with an increased risk of myocardial infarction and stroke but it remains unclear how to identify microvascular changes in this population. OBJECTIVES: We hypothesized that simple non-mydriatic retinal photography is feasible and can be used to assess microvascular damage in COPD. METHODS: Novel Vascular Manifestations of COPD was a prospective study comparing smokers with and without COPD, matched for age. Non-mydriatic, retinal fundus photographs were assessed using semi-automated software. RESULTS: Retinal images from 24 COPD and 22 control participants were compared. Cases were of similar age to controls (65.2 vs. 63.1 years, p = 0.38), had significantly lower Forced Expiratory Volume in one second (FEV1) (53.4 vs 100.1% predicted; p < 0.001) and smoked more than controls (41.7 vs. 29.6 pack years; p = 0.04). COPD participants had wider mean arteriolar (155.6 ±15 uM vs. controls [142.2 ± 12 uM]; p = 0.002) and venular diameters (216.8 ±20.7 uM vs. [201.3± 19.1 uM]; p = 0.012). Differences in retinal vessel caliber were independent of confounders, odds ratios (OR) = 1.08 (95% confidence intervals [CI] = 1.02, 1.13; p = 0.007) and OR = 1.05 (CI = 1.01, 1.09; p = 0.011) per uM increase in arteriolar and venular diameter respectively. FEV1 remained significantly associated with retinal vessel dilatation r = -0.39 (p = 0.02). CONCLUSIONS: Non-mydriatic retinal imaging is easily facilitated. We found significant arteriole and venous dilation in COPD compared to age-matched smokers without COPD associated with lung function independent of standard cardiovascular risk factors. Retinal microvascular changes are known to be strongly associated with future vascular events and retinal photography offers potential to identify this risk. TRIAL REGISTRATION: clinicaltrials.gov NCT02060292
Recommended from our members
On the entropic stabilisation of an Al<inf>0.5</inf>CrFeCoNiCu high entropy alloy
The extent to which configurational entropy can stabilise a single solid solution in an Al0.5CrFeCoNiCu high entropy alloy has been assessed through characteristion of samples following casting and heat treatment at 1000 C. At temperatures between 1000 C and the onset of melting, the alloy was shown to be within a two phase field and these phases were stable following prolonged exposure at elevated temperature. X-ray and transmission electron diffraction indicated that both constituent phases had an fcc structure. Therefore, these phases share a Gibbs energy curve that must contain two local minima at the solidus temperature, rather than the single minimum required for a continuous solid solution. These
observations indicate that there is no temperature at which this material is in a stable, solid state single phase field and that therefore, the configurational complexity is insufficient to stabilise a solid solution phase against enthalpic effects.EPSRC/Rolls-Royce Strategic partnership for funding (NGJ, AB and HJS under EP/H500375/1, JWA and BDC under EP/H022309/1).This is the final published manuscript distributed under a Creative Commons Attribution License 2.0 UK. This article can also be viewed on the publisher's website at: http://www.sciencedirect.com/science/article/pii/S0966979514001848
Quantifying interspecific variation in dispersal ability of noctuid moths using an advanced tethered flight technique
This is the final version. Available on open access from Wiley via the DOI in this recordDispersal plays a crucial role in many aspects of species' life histories, yet is often difficult to measure directly. This is particularly true for many insects, especially nocturnal species (e.g. moths) that cannot be easily observed under natural field conditions. Consequently, over the past five decades, laboratory tethered flight techniques have been developed as a means of measuring insect flight duration and speed. However, these previous designs have tended to focus on single species (typically migrant pests), and here we describe an improved apparatus that allows the study of flight ability in a wide range of insect body sizes and types. Obtaining dispersal information from a range of species is crucial for understanding insect population dynamics and range shifts. Our new laboratory tethered flight apparatus automatically records flight duration, speed, and distance of individual insects. The rotational tethered flight mill has very low friction and the arm to which flying insects are attached is extremely lightweight while remaining rigid and strong, permitting both small and large insects to be studied. The apparatus is compact and thus allows many individuals to be studied simultaneously under controlled laboratory conditions. We demonstrate the performance of the apparatus by using the mills to assess the flight capability of 24 species of British noctuid moths, ranging in size from 12-27 mm forewing length (~40-660 mg body mass). We validate the new technique by comparing our tethered flight data with existing information on dispersal ability of noctuids from the published literature and expert opinion. Values for tethered flight variables were in agreement with existing knowledge of dispersal ability in these species, supporting the use of this method to quantify dispersal in insects. Importantly, this new technology opens up the potential to investigate genetic and environmental factors affecting insect dispersal among a wide range of species.Rothamsted Research receives grant aided support from the Biotechnology and Biological Sciences Research Council. H.B.C.J. was funded by a BBSRC Quota studentship awarded to J.W.C. and J.K.H
Proof Relevant Corecursive Resolution
Resolution lies at the foundation of both logic programming and type class
context reduction in functional languages. Terminating derivations by
resolution have well-defined inductive meaning, whereas some non-terminating
derivations can be understood coinductively. Cycle detection is a popular
method to capture a small subset of such derivations. We show that in fact
cycle detection is a restricted form of coinductive proof, in which the atomic
formula forming the cycle plays the role of coinductive hypothesis.
This paper introduces a heuristic method for obtaining richer coinductive
hypotheses in the form of Horn formulas. Our approach subsumes cycle detection
and gives coinductive meaning to a larger class of derivations. For this
purpose we extend resolution with Horn formula resolvents and corecursive
evidence generation. We illustrate our method on non-terminating type class
resolution problems.Comment: 23 pages, with appendices in FLOPS 201
Recommended from our members
COPD patients hospitalized with exacerbations have greater cognitive impairment than patients hospitalized with decompensated heart failure
Purpose: People with COPD have cognitive dysfunction, which is greater in those hospitalized for exacerbations than in stable outpatients. We tested the hypothesis that cognitive dysfunction at exacerbation is a disease-specific feature of COPD, rather than a nonspecific feature of hospitalization for acute illness, by comparing cognition between patients hospitalized for acute COPD exacerbations and those with worsening heart failure (HF).
Patients and methods: A total of 40 hospital inpatients were recruited, 20 patients with COPD exacerbations and 20 patients with congestive or left-sided HF. Exclusion criteria included previous stroke, known neurological disease, and marked alcohol excess. Participants completed the Montreal cognitive assessment (MoCA) and Hospital Anxiety and Depression Scale (HADS) and underwent spirometry and review of clinical records.
Results: Age (mean±SD, COPD 73±10; HF 76±11 years), acute illness severity (Acute Physiology and Chronic Health Evaluation [APACHE]-II, COPD 15.4±3.5; HF 15.9±3.0), comorbidities (Charlson index, COPD 1.3±1.9; HF 1.6±1.5), and educational background were similar between COPD and HF groups. MoCA total was significantly lower in COPD than in HF (COPD 20.6±5.6; HF 24.8±3.5, P=0.007); however, significance was lost after correction for age, sex, and pack year smoking history. When compared with HF patients, the COPD cohort performed worse on the following domains of the MoCA: visuospatial function (median [IQR], COPD 0 [1]; HF 2 [1], P=0.003), executive function (COPD 2 [1]; HF 3 [1], P=0.035), and attention (COPD 4 [3]; HF 6 [2], P=0.020). Age (P=0.012) and random glucose concentration (P=0.041) were associated with cognitive function in whole group analysis, with pack year smoking history reaching borderline significance (P=0.050).
Conclusion: Total MoCA score for COPD and HF indicated that both groups had mild cognitive impairment, although this was greater in people with COPD. Mechanisms underlying the observed cognitive dysfunction in COPD remain unclear but appear related to blood glucose concentrations and greater lifetime smoking load
Preliminary development of a questionnaire to measure the extra-pulmonary symptoms of severe asthma.
BACKGROUND: Research into the effects of asthma treatments on the extra-pulmonary symptoms of severe asthma is limited by the absence of a suitable questionnaire. The aim was to create a questionnaire suitable for intervention studies by selecting symptoms that are statistically associated with asthma pathology and therefore may improve when pathology is reduced. METHODS: Patients attending a specialist asthma clinic completed the 65-item General Symptom Questionnaire (GSQ-65), a questionnaire validated for assessing symptoms of people with multiple medically unexplained symptoms. Lung function (FEV1%) and cumulative oral corticosteroids (OCS) calculated from maintenance dose plus exacerbations were obtained from clinic records. Pathology was represented by the two components of a principal component analysis (PCA) of FEV1% and OCS. LASSO regression was used to select symptoms that had high coefficients with these two principal components and occurred frequently in severe asthma. RESULTS: 100 patients provided data. PCA revealed two components, one where FEV1% and OCS were inversely related and another where they were directly related. LASSO regression revealed 39 symptoms with non-zero coefficients on one or more of the two principal components from which 16 symptoms were selected for the GSQ-A on the basis of magnitude of coefficient and frequency. Asthma symptoms measured by asthma control questionnaires were excluded. The GSQ-A correlated 0.33 and - 0.34 (p = 0.001) with the two principal components. CONCLUSION: The GSQ-A assesses the frequency of 16 heterogenous non-respiratory symptoms that are associated with asthma severity using the statistical combination of FEV1% and OCS
Long-term survival rates of laryngeal cancer patients treated by radiation and surgery, radiation alone, and surgery alone : studied by lognormal and Kaplan-Meier survival methods
BACKGROUND: Validation of the use of the lognormal model for predicting long-term survival rates using short-term follow-up data. METHODS: 907 cases of laryngeal cancer were treated from 1973–1977 by radiation and surgery (248), radiation alone (345), and surgery alone (314), in registries of Connecticut and Metropolitan Detroit of the SEER database, with known survival status up to 1999. Phase 1 of this study used the minimum chi-square test to assess the goodness of fit of the survival times of those who died with disease to a lognormal distribution. Phase 2 used the maximum likelihood method to estimate long-term survival rates using short-term follow-up data. In order to validate the lognormal model, the estimated long-term cancer-specific survival rates (CSSR) were compared with the values calculated by the Kaplan-Meier (KM) method using long-term data. RESULTS: The 25-year CSSR were predicted to be 72%, 68% and 65% for treatments by radiation and surgery, by radiation alone, and by surgery alone respectively, using short-term follow-up data by the lognormal model. Corresponding results calculated by the KM method were: 72+/-3%, 68+/-3% and 66+/-4% respectively. CONCLUSIONS: The lognormal model was validated for the prediction of the long-term survival rates of laryngeal cancer patients treated by these different methods. The lognormal model may become a useful tool in research on outcomes
- …