1,720,963 research outputs found
Altered blood-brain barrier permeability is associated with abnormal distant connectivity and regional homogeneity in covert hepatic encephalopathy-A cross-sectional study
No full textBackground: Covert hepatic encephalopathy (CHE) is clinically underrecognized. Using MRI, we explored the relationship between functional connectivity as a marker of executive dysfunction and the blood-brain barrier permeability marker KTRANS in a cross-sectional cohort of covert HE (CHE), no HE (NHE), and healthy controls (HC). Methods: This study was a single-center prospective cohort study conducted between 2018 and 2021. CHE was diagnosed using the Psychometric Hepatic Encephalopathy Score (PHES) with an abnormality threshold of <-4. Blood brain barrier permeability was determined using MRI KTRANS, based on cerebral efflux of gadolinium from blood plasma to the extravascular space. Resting-state fMRI determined the intrinsic dynamics of regions of the brain. Results: Three cohorts were recruited: cirrhosis and CHE (n=17); cirrhosis with no HE (NHE; n=13); and healthy controls (n=10). There was a significant negative correlation (r=-0.59, p=0.003) between KTRANS and components of the Default Mode Network (DMN). Group-level ANOVA (F-test) revealed a significant difference between groups in functional connectivity within the Salience Network (SN) (Cluster level significance, F(4,62)=8.45, pcorrected=0.000005) and the DMN (Cluster level significance, F(4,62)=6.20, pcorrected=0.0004). The analysis revealed significant differences in regional homogeneity between the CHE and Health Controls. Conclusion: There was a strong association between disrupted blood-brain barrier (BBB) integrity and attenuated functional connectivity, with reductions in functional connectivity within the DMN and Frontoparietal Network (FPN), circuits closely linked to executive control. This attenuation was evident both in local regional and in distant connectivity within these networks
HCC incidence after hepatitis C cure among patients with advanced fibrosis or cirrhosis: A meta-analysis
Get PDFBackground and aims: HCV cure reduces but does not eliminate the risk of HCC. HCC surveillance is recommended in populations where the incidence exceeds 1.5% per year. In cirrhosis, HCC surveillance should continue after HCV cure, although it is uncertain if this should be indefinite. For patients with advanced fibrosis (F3), guidelines are inconsistent in their recommendations. We evaluated the incidence of HCC after HCV cure among patients with F3 fibrosis or cirrhosis. Approach and results: This systematic review and meta-analysis identified 44 studies (107,548 person-years of follow-up) assessing the incidence of HCC after HCV cure among patients with F3 fibrosis or cirrhosis. The incidence of HCC was 2.1 per 100 person-years (95% CI, 1.9-2.4) among patients with cirrhosis and 0.5 per 100 person-years (95% CI, 0.3-0.7) among patients with F3 fibrosis. In a meta-regression analysis among patients with cirrhosis, older age (adjusted rate ratio [aRR] per 10-year increase in mean/median age, 1.32; 95% CI, 1.00-1.73) and prior decompensation (aRR per 10% increase in the proportion of patients with prior decompensation, 1.06; 95% CI, 1.01-1.12) were associated with an increased incidence of HCC. Longer follow-up after HCV cure was associated with a decreased incidence of HCC (aRR per year increase in mean/median follow-up, 0.87; 95% CI, 0.79-0.96). Conclusions: Among patients with cirrhosis, the incidence of HCC decreases over time after HCV cure and is lowest in patients with younger age and compensated cirrhosis. The substantially lower incidence in F3 fibrosis is below the recommended threshold for cost-effective screening. The results should encourage the development of validated predictive models that better identify at-risk individuals, especially among patients with F3 fibrosis
Novel magnetic resonance KTRANS measurement of blood-brain barrier permeability correlated with covert HE
Get PDFBackground: Using dynamic contrast-enhanced (DCE) MR perfusion and MR spectroscopy this study aimed to characterize the blood-brain barrier permeability and metabolite changes in patients with cirrhosis and without covert HE. Methods: Covert HE was defined using psychometric HE score (PHES). The participants were stratified into 3 groups: cirrhosis with covert HE (CHE) (PHES<-4); cirrhosis without HE (NHE) (PHES≥-4); and healthy controls (HC). Dynamic contrast-enhanced MRI and MRS were performed to assess KTRANS, a metric derivative of blood-brain barrier disruption, and metabolite parameters. Statistical analysis was performed using IBM SPSS (v25). Results: A total of 40 participants (mean age 63 y; male 71%) were recruited as follows: CHE (n=17); NHE (n=13); and HC (n=10). The KTRANS measurement in the frontoparietal cortex demonstrated increased blood-brain barrier permeability, where KTRANS was 0.01±0.02 versus 0.005±0.005 versus 0.004±0.002 in CHE, NHE, and HC patients, respectively (p = 0.032 comparing all 3 groups). Relative to HC with a value of 0.28, the parietal glutamine/creatine (Gln/Cr) ratio was significantly higher in both CHE 1.12 mmoL (p < 0.001); and NHE 0.49 (p = 0.04). Lower PHES scores correlated with higher glutamine/Cr (Gln/Cr) (r=-0.6; p < 0.001) and lower myo-inositol/Cr (mI/Cr) (r=0.6; p < 0.001) and lower choline/Cr (Cho/Cr) (r=0.47; p = 0.004). Conclusion: The dynamic contrast-enhanced MRI KTRANS measurement revealed increased blood-brain barrier permeability in the frontoparietal cortex. The MRS identified a specific metabolite signature with increased glutamine, reduced myo-inositol, and choline, which correlated with CHE in this region. The MRS changes were identifiable in the NHE cohort
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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