1,720,955 research outputs found
Phosphodiesterase inhibitors correct resistance to natriuretic peptides in rats with Heymann nephritis
No full textExperimental nephrotic syndrome is characterized by abnormal sodium metabolism, reflected in a blunted natriuretic response both to volume expansion and to infused atrial natriuretic peptide (ANP), The studies presented here examined the relationships among plasma ANP concentration and urinary sodium (UNaV) and cyclic GMP excretion (UcGMPV) in vivo, and the responsiveness of isolated glomeruli and inner medullary collecting duct (IMCD) cells to ANP and urodilatin (renal natriuretic peptide; RNP) in vitro in rats with Heymann nephritis, an immunologically mediated model of nephrotic syndrome, Nine to 14 days after ip injection of anti-Fx1A antiserum, rats were proteinuric and had a blunted natriuretic response to intravenous infusion of isotonic saline (2% body weight, given over 5 min). Thirty min after the onset of the infusion, plasma ANP concentration was increased to the same extent in both normal and nephritic rats, compared with their respective hydropenic controls, Despite this increase, UcGMPV was significantly less in nephritic rats after the saline infusion, Accumulation of cGMP by isolated glomeruli and IMCD cells from nephritic rats after incubation with ANP and RNP was also significantly reduced, compared with normal rats. This difference was not related to differences in either density or affinity of renal ANP receptors, but was abolished when accumulation of cGMP was measured in the presence of 10(-3) M isobutylmethylxanthine or Zaprinast, two different inhibitors of cyclic nucleotide phosphodiesterases (PDE), Infusion of Zaprinast into one renal artery in nephritic rats normalized both the natriuretic response to volume expansion and the increase in UcGMPV from the infused, but not the contralateral, kidney. Furthermore, cGMP-PDE activity was increased in IMCD cell homogenates from nephritic compared with normal rats (388 +/- 32 versus 198 +/- 93 pmol/min per mg protein, P < 0.03). These results indicate that blunted volume expansion natriuresis accompanied by cellular resistance to ANP in vitro occurs in an immunologic model of renal injury, The resistance is not related to an alteration in ANP release or binding to its renal receptors, but is suppressed by PDE inhibitors and is associated with increased renal cGMP PDE activity, thus suggesting that enhanced cGMP-PDE activity may account for resistance to the natriuretic actions of ANP observed in vivo. This defect may represent the intrinsic sodium transport abnormality linked to sodium retention in nephrotic syndrome
URODILATIN BINDS TO AND ACTIVATES RENAL RECEPTORS FOR ATRIAL-NATRIURETIC-PEPTIDE
No full textUrodilatin is a recently described member of the atrial natriuretic peptide family, thought possibly to be synthesized in the kidney. To determine if urodilatin binding sites are present in rat and human kidney, we evaluated the effect of urodilatin on iodine-125-labeled atrial natriuretic peptide (ANP) (100 pM) binding to tissue sections using an in situ autoradiographic technique. I-125-ANP binding occurred primarily in glomeruli and medullary structures of both rat and human kidney. Increasing concentrations of urodilatin yielded a monophasic displacement of I-125-ANP binding with an IC50 of 4.2 nM, a value nearly identical to that achieved with unlabeled ANP (7.2 nM). In additional experiments, rat glomeruli and inner medullary collecting duct cells were isolated and incubated in vitro with either ANP or urodilatin (10(-11) to 10(-6) M) and cyclic guanosine-3',5'-monophosphate accumulation measured by radioimmunoassay. Dose-response curves for the two peptides were superimposable in each tissue; at 10(-6) M, ANP generated 613+/-41 and urodilatin 603+/-55 fmol cyclic guanosine monophosphate per 10 minutes per milligram protein in inner medullary collecting duct cells (p = NS). Thus, urodilatin is as effective as ANP in displacing I-125-ANP binding to both rat and human renal tissue and in generating cyclic guanosine monophosphate in renal target cells in the rat, suggesting that its physiological effects may occur through the same receptors and signaling pathways that mediate the actions of ANP
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
