1,720,962 research outputs found
Heterogeneous transmural gene expression of calcium-handling proteins and natriuretic peptides in the failing human heart
No full textObjective: Human heart failure is associated with a disturbed intracellular calcium (Ca2+) homeostasis. In this regard, ventricular wall stress is considered to be a determinant for expression of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a). In the present study, we analyzed the transmural protein and/or mRNA levels of SERCA2a, other Ca2+-handling proteins, and of atrial and brain natriuretic peptides (ANP and BNP) in the human heart. Methods: Subepicardial (epi), midmyocardial (mid), and subendocardial (endo) sections of the left ventricular free wall from end-stage failing (n=17) and nonfailing (n=5) human hearts were analyzed by Western blot for immunoreactive protein levels of SERCA2a, phospholamban (PLN), and calsequestrin (CS). Subepi- and subendocardial sections were analyzed by Northern blot for steady-state mRNA levels of SERCA2a, Na+-Ca2+ exchanger (NCX1), ANP, and BNP. Results: SERCA2a protein and mRNA levels were reduced by 40±5% (P<0.01) and 25±7% (P<0.05) in endo compared to epi in the failing heart and by 27±14% and 16±12% (non-significant) in the nonfailing heart, respectively. PLN protein levels were reduced by 23±6% (P<0.05) in endo compared to epi in the failing heart and by 17±25% (non-significant) in the nonfailing heart, whereas CS protein levels and NCX1 mRNA levels were similar across the left ventricular wall. Strikingly, in the failing heart, both BNP and ANP mRNA levels were upregulated predominantly in endo. Conclusions: In the failing human heart, SERCA2a and PLN, as well as natriuretic peptides but not CS and NCX1 are differentially expressed across the left ventricular wall, implicating (1) different susceptibility of subendocardium and subepicardium to factors affecting expression of these proteins and (2) differences in regulation of the distinct calcium-cycling proteins
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
Downregulation of the Na(+)-creatine cotransporter in failing human myocardium and in experimental heart failure.
No full textBACKGROUND:The failing myocardium is characterized by depletion of phosphocreatine and of total creatine content. We hypothesized that this is due to loss of creatine transporter protein. METHODS AND RESULTS:Creatine transporter protein was quantified in nonfailing and failing human myocardium (explanted hearts with dilated cardiomyopathy [DCM; n=8] and healthy donor hearts [n=8]) as well as in experimental heart failure (residual intact left ventricular tissue, rats 2 months after left anterior descending coronary artery ligation [MI; n=8] or sham operation [sham; n=6]) by Western blotting. Total creatine content was determined by high-performance liquid chromatography. Donor and DCM hearts had total creatine contents of 136.4+/-6.1 and 68.7+/-4.6 nmol/mg protein, respectively (*P<0.05); creatine transporter protein was 25.4+/-2.2 optical density units in donor and 17.7+/-2.5 in DCM (*P<0.05). Total creatine was 87.5+/-4.2 nmol/mg protein in sham and 65.7+/-4.2 in MI rats (*P<0.05); creatine transporter protein was 139.0+/-8.7 optical density units in sham and 82.1+/-4.0 in MI (*P<0.05). CONCLUSIONS:Both in human and in experimental heart failure, creatine transporter protein content is reduced. This mechanism may contribute to the depletion of creatine compounds and thus to the reduced energy reserve in failing myocardium. This finding may have therapeutic implications, suggesting a search for treatment strategies targeted toward creatine transport
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
Impaired Contractile Performance of Cultured Rabbit Ventricular Myocytes After Adenoviral Gene Transfer of Na+-Ca2+ Exchanger
No full textNa+-Ca2+ exchanger (NCX) gene expression is increased in the failing human heart. We investigated the hypothesis that upregulation of NCX can induce depressed contractile performance, Overexpression of NCX was achieved in isolated rabbit ventricular myocytes through adenoviral gene transfer (Ad-NCX). After 48 hours, immunoblots revealed a virus dose-dependent increase in NCX protein. Adenoviral beta-galactosidase transfection served as a control. The fractional shortening (FS) of electrically stimulated myocytes was analyzed. At 60 min(-1), FS was depressed by 15.6% in the Ad-NCX group (n=143) versus the control group (n=163, P<0.05). Analysis of the shortening-frequency relationship showed a steady increase in FS in the control myocytes (n=26) from 0.027+/-0.002 at 30 min(-1) to 0.037+/-0.002 at 120 min(-1) (P<0.05 versus 30 min(-1)) and to 0.040+/-0.002 at 180 min(-1) (P<0.05 versus 30 min(-1)). Frequency potentiation of shortening was blunted in NCX-transfected myocytes (n=27). The FS was 0.024+/-0.002 at 30 min(-1), 0.029+/-0.002 at 120 min(-1) (P<0.05 versus 30 min(-1), P<0.05 versus control), and 0.026+/-0.002 at 180 min(-1) (NS versus 30 min(-1), P<0.05 versus control). Caffeine contractures, which indicate sarcoplasmic reticulum Ca2+ load, were significantly reduced at 120 min(-1) in NCX-transfected cells. An analysis of postrest behavior showed a decay of FS with longer rest intervals in control cells. Rest decay was significantly higher in the Ad-NCX group; after 120 seconds of rest, FS was 78+/-4% in control and 65+/-3% in the Ad-NCX group (P<0.05) relative to steady-state FS before rest (100%). In conclusion, the overexpression of NCX in rabbit cardiomyocytes results in the depression of contractile function. This supports the hypothesis that upregulation of NCX can result in systolic myocardial failure
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