1,721,041 research outputs found
Renal bioengineering with scaffolds generated from rat and pig kidneys
No full textBackground: Chronic kidney disease (CKD) is a global public health issue with an estimated prevalence of 8-16% worldwide. End-stage renal disease eventually develops every year in 0.15-0.2% of patients with overt CKD, and renal replacement therapy (RRT) with dialysis or transplantation is required. Although approximately 2 million people worldwide are currently on RRT to sustain life, this likely represents less than 10% of those who need it. The kidney transplant approach is also seriously impaired by limited graft survival and by the scarce availability of donors. Innovative tissue-engineering strategies have been recently proposed to overcome these challenges. It is anticipated that these novel approaches will also be cost-effective in the long term. Although the initial setup of these innovative technologies could be quite expensive, there would be a single application for each patient, with no additional costs thereafter, compared to the lifelong costs of dialysis or immunosuppressive medications required for transplantation. One of the most innovative tools currently being investigated in experimental models is based on the idea of using decellularized kidneys to engineer a new functional organ as a potential future treatment option for end-stage renal disease. Summary: In the last 5 years, several interesting observations have been reported regarding the possibility of using an acellular matrix from the whole kidney and the attempt to recellularize this scaffold using stem or differentiated cells. This review provides an overview of the decellularization methods tested so far and their effects on the resulting extracellular matrix structure and composition. In addition, we also discuss methods recently described by us and others for the perfusion of kidney scaffolds for recellularization. Key Messages: Despite difficulties in achieving the import goal of kidney engineering in the laboratory, we discuss the problems with and limits of the experimental results obtained so far and point out the strategies that need to be adopted in order for this line of research to advance
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Effect of anastomosis angle on the localization of disturbed flow in ‘side-to-end’ fistulae for haemodialysis access.
No full textBackground - Early failure of vascular access (VA) for haemodialysis (HD) after the surgery of radial-cephalic arteriovenous fistula (AVF) occurs mainly due to a juxta-anastomotic stenosis. Even if the elevated blood flow induces high wall shear stresses (WSS), we have recently shown that disturbed flow, characterized by low and reciprocating flow, may develop in zones of the AVF that locate well the sites of future stenosis. The present study was aimed at investigating whether the anastomosis angle influences disturbed flow in radial-cephalic end-to-side AVF.
Methods - By means of a parametric AVF model we created four equivalent meshes having the anastomotic angle of 30°, 45°, 60° and 90°, respectively. We then performed transient, non-Newtonian computational fluid dynamics (CFD) simulations using as boundary conditions previously measured blood volume flow and division ratio in subjects requiring primary access. The relative residence time (RRT), a robust indicator of disturbed flow, was calculated for the overall wall surface and disturbed flow was localized by areas having RRT > 1. Quantitative characterization and statistical tests were employed to assess the difference in RRT medians between the four anastomosis angle cases.
Results - Disturbed flow was located in all AVF models in the same areas where flow recirculation and stagnation occurs, on the inner wall of the swing segment (SS) and on the arterial wall at the anastomosis floor (AF). Smaller angle AVF had smaller disturbed flow areas with lower RRT peak values, either on the vein or the arterial limb. There were significant differences in the RRT medians on the SS and on the AF between sharper (30° and 45°) and wider (60° or 90°) angles.
Conclusions - We have found that in end-to-side radial-cephalic AVF for HD the anastomosis angle does impact on the local disturbed flow patterns. Among the four geometries we considered in this study, the smaller angle (30°) would be the preferred choice that minimizes development of neointima. Clinicians should consider this at the time of AVF creation because anastomosis angle is in part amenable to surgical manipulation
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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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