1,721,133 research outputs found
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
Impairment of tight junctions and glucose transport in endothelial cells of human cerebral cavernous malformations
Full text linkCerebral cavernous malformations (CCMs) often cause hemorrhages that can result in severe clinical manifestations, including hemiparesis and seizures. The underlying mechanisms of the aggressive behavior of CCMs are undetermined to date, but alterations of vascular matrix components may be involved. We compared the localization of the tight junction proteins (TJPs) in 12 CCM specimens and the expression of glucose transporter 1 (GLUT-1), which is sensitive to alterations in TJP levels, in 5 CCM specimens with those in 5 control temporal lobectomy specimens without CCM by immunofluorescence microscopy. The TJPs occludin, claudin-5, and zonula occludens ZO-1 were downregulated at intercellular contact sites and partly redistributed within the surrounding tissue in the CCM samples; there was also a marked reduction of GLUT-1 immunoreactivity compared with that in control specimens. Corresponding analysis using quantitative real-time reverse transcription polymerase chain reaction on 8 CCM and 8 control specimens revealed significant downregulation of mRNA expression of occludin, claudin-5, ZO-1, and GLUT-1. The altered expression and localization of the TJPs at interendothelial contact sites accompanied by a reduction of GLUT-1 expression in dilated CCM microvessels likely affect vascular matrix stability and may contribute to hemorrhages of CCMs
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
Different gene expressions of Wif1 and Rab34 in glioblastomas
No full textOnkologische Reaktionswege, bei denen unter anderem die Wnt-Protein-Familie
und die Ras-Gene eine bedeutende Rolle spielen, stehen im Interesse der derzeitigen medizinischen Forschung. Sowohl das Gen Wif1 als auch Rab34 könnten
möglicherweise auch als wichtige Schaltpunkte innerhalb der Gliomgenese dienen.
Wif1 ist ein extrazellulär lokalisierter Antagonist des Wnt und wirkt über eine
direkte Bindung an Wnt-Liganden. Über eine intrazelluläre Herunterregulation von
β-Catenin kommt es zu einer verminderten Ausbildung von Onkogenen. Im Gegensatz dazu geht eine Abnahme von Wif1 mit einem Expressionsanstieg von Wnt einher, so dass es über die β-Catenin-Kaskade zu einer gesteigerten Transkriptionsaktivität kommt.
Rab34 gehört zu der Gruppe der Ras-Gene und ist in verschiedenste Stufen der
Endo- und Exozytose involviert. Die Rab-Proteine regulieren Transportwege durch
die Membran, indem sie als molekulare Schalter zwischen der aktiven und der
inaktiven Form agieren. Im aktiven Status erfüllen Rab-Proteine ihre Funktion bei der Vesikelformation und bei der Bewegung von Organellen sowie Membranspaltung/-fusionen durch die Rekrutierung von Effektor-Proteinen.
Basierend auf vorausgegangenen Microarray-Analysen, in denen ein signifikanter
Unterschied in der Gen-Expression von Rab34 und Wif1 in Astrozytomen Grad III
und Glioblastomen nachgewiesen werden konnte, wurde in der vorliegenden Arbeit
mittels semiquantitativer Real-Time-PCR das unterschiedliche Expressionsmuster
von Rab34 und Wif1 in Astrozytomen Grad II, Grad III, in Glioblastomen und
Glioblastom-Rezidiven untersucht. Die Patienten mit Glioblastom-Rezidiven waren
mit gleicher Radio-Chemo-Therapie einmalig vorbehandelt worden. Die Gesamtzahl
von 51 Tumorproben wurde mittels eines ABI™ Sequence Detection Systems ABI
PRISM® 7700 and Qiagen™ QuantiTect® SYBR® Green PCR Kits experimentell
untersucht. Die statistische Überprüfung erfolgte mittels U-Test.
Für das Gen Wif1 konnten signifikante Expressionsunterschiede im Vergleich
zwischen Astrozytomen Grad III und der Gruppe der Rezidive sowie zwischen
Glioblastomen und den Rezidiven festgestellt werden Beim Vergleich der Expressionsstärke von Rab34 zwischen den Glioblastom-Gruppen zeigte sich eine Verdoppelung der Werte vom Glioblastom verglichen mit seinen Rezidiven. Im U-Test/Mann-Whitney-Test war dieser Expressionsunterschied statistisch signifikant.
Eine veränderte Aktivierung des Wnt-Reaktionsweges bzw. ein Ungleichgewicht der
Über- und Unterexpression von Wif1 scheint eine zentrale Rolle bei der
Tumorgenese von Astrozytomen zu spielen. Es scheint aber keine Korrelation
zwischen dem Malignitätsgrad des Tumors und der Expression von Wif1 zu geben.
In einigen Tumoren wie Blasen- oder Prostata-Karzinom korreliert die Wif1-
Expression mit dem Tumorgrad. In der vorliegenden Arbeit bestätigt sich dieser
Zusammenhang für Astrozytome nicht. Ein Expressionsanstieg kann sowohl eine
anti-apoptotische Aktivität als auch eine potenzierte Malignität bedeuten.
Für das zweite untersuchte Gen Rab34 konnte mit den vorliegenden Versuchen die
Vermutung einer Assoziation zwischen der Gen-Expression und dem Tumor-Grad
bestätigt werden. Aus den signifikanten Expressionsunterschieden zwischen
Glioblastomen und den mit Radio- und Chemo-Therapie behandelten Rezidiven
geht ferner hervor, dass hier möglicherweise ein sehr sensibler Schritt innerhalb des Rab34-Pathways (Reaktionsweges) zugrunde liegt. Hier sei auf die zentrale Rolle von Rab34 innerhalb des Organellen-Transportes im Axoplasma, auf Mikrotubulusabhängige Effekte und die Regulation der Antigen-Präsentation verwiesen.Major oncologic pathways, such as the Wnt protein family and the Ras genes belong to oncogenes that play a significant role in tumor genesis pathways. Wif1 and Rab34 have been implicated to be involved in glioma genesis.
Wif1 is a secreted antagonist of Wnt signalling and functions by direct binding to Wnt ligands in the extracellular space. There is evidence that intracellular downregulation of β-catenin correlates with reduced expression of oncogenes. On the other hand down-regulation of Wif1 results in a higher expression level of Wnt, which causes higher transcription activity through the β-catenin pathway.
Rab34 belongs to the group of Ras genes and is involved in various steps along the exocytic and endocytic pathways. By changing between the active and inactive
form, Rab-proteins are considered key regulatory factors for membrane traffic. This biological activity causes vesicular formation, movement of organelles and
membrane traffic by recruitment of effector proteins.
Previous microarray analysis showed a significant incidence of different gene
expressions of Rab34 and Wif1 in astrocytomas of WHO-grade III and glioblastomas. The current study analysed the incidence of Wif1 and Rab34
expression in a larger number of tissue samples from astrocytomas of WHO-grades
II, III, glioblastomas and first-time recurrent glioblastomas. Last-mentioned were treated by radiation and chemo-therapy.
To study possible differences in their expression, semiquantitative two-step RT
Real-Time PCR examinations on a total of 51 tissue samples of astrocytomas WHOgrade II, III, glioblastomas and first-time recurrent glioblastomas were performed.
Analysis were conducted using the ABI™ Sequence Detection System ABI PRISM® 7700 and Qiagen™ QuantiTect® SYBR® Green PCR Kits. According to the histological grading the arithmetic mean was calculated and compared by using the U-test.
There is an immense uptake of Wif1 in astrocytomas from grade II to grade III.
Strong reduction of Wif1 expression was present in glioblastomas compared to
astrocytomas grade III. The expression level of astrocytomas grade II was nearly
equivalent to the group of glioblastomas. Another up-regulation of Wif1-expression was seen in recurrent compared to primary glioblastomas. By using the U-test, there was a significant difference in expression level between astrocytomas grade III and recurrent glioblastomas as well as recurrent compared to primary glioblastomas.
Rab34 showed the highest expression in astrocytomas grade III and displayed a
strong reduction compared to the benign astrocytomas grade II. Moreover, Rab34-
expression showed a down-regulation of astrocytomas grade III compared to
primary glioblastomas. Expression level of Rab34 in glioblastomas showed a double increase from primary to recurrent glioblastomas. By using the U-test there was a significant difference in expression levels between recurrent when compared to primary glioblastomas.
Both pathways may be operative in early glioma tumor genesis. Aberrant activation of the Wnt pathway indicates that loss of Wif1 expression may be an early event in tumor genesis as demonstrated by other groups for higher tumor stages like urinary bladder or prostate cancer. The data indicates that there is no correlation between tumorgrade and expression level of Wif1, but this probably demonstrates tissuespecific or tumor-specific expression. There is evidence for anti-apoptotic activity and potentiated malignity.
Overexpression of Rab GTPases is detected in various kinds of cancer. The
increasing expression of Rab34 in all glioma grades supports the previously
suggested role of tumor genesis for astrocytomas. There is significant correlation between tumor stage and tumor-grade. Because of the uptake in expression level between recurrent when compared to primary glioblastomas, the Rab34 pathway might play an important role. On the basis of this result, membrane traffic in the axoplasma, microtubules- or actin-based motor complexes and regulation within the antigenic presentation may yield additional understanding
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
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