1,720,958 research outputs found
PCNA immunostaining as a valid alternative to tritiated thymidine-autoradiography to detect proliferative cell fraction in transitional cell bladder carcinomas
No full textBACKGROUND: The thymidine labeling index (T-LI) evaluated with the autoradiographic technique on fresh specimens is the most objective and specific marker of tumor proliferative cell fraction. In this study we investigated T-LI and PCNA expression in 68 cases of transitional cell bladder carcinomas in order to evaluate whether PCNA immunostaining in paraffin sections could be a valid alternative to autoradiographic methods for cell kinetic detection. Immunohistochemistry was applied after different fixatives: usual formalin, neutral 4% buffered formalin and Bouin. The results revealed that only in buffered formalin-fixed tumor specimens, considering the most darkly stained cells, the PCNA-LI in all cases overlapped with T-LI. Higher values than those observed with autoradiography were detected in PCNA values obtained after usual formalin fixation whereas no or faint PCNA staining was seen in material fixed in Bouin. Thus, only cells with strong PCNA staining can be considered as significant in evaluating the proliferative activity in transitional cell bladder carcinoma. By using immunohistochemical methods it should thus be possible to overcome many of the inherent difficulties of autoradiography and likewise to obtain accurate and significant information on the biological aggressiveness of bladder tumors and consequently of patient prognosis
Involvement of the EN-2 gene in normal and abnormal development of the human arcuate nucleus
No full textIn this study, we wanted to evaluate whether the engrailed EN-2 gene, a homeobox gene with an essential role in the development of the rhombic lip derivatives in different species, is (1) expressed also in man in the differentiation process of the medullary arcuate nucleus (ArcN) and (2) involved in sudden unexplained perinatal and infant death, frequently related to developmental defects of the ArcN. We evaluated by means of the monoclonal antibody 4D9, exclusively recognizing engrailed-2 protein, the expression of the EN-2 gene in the ArcN on histological sections of the brainstems of 30 subjects aged from 17 gestational weeks to 10 postnatal months, who had died of known (17 cases) and unknown causes (13 cases). We observed in the greater number of the cases that the expression of the EN-2 gene is very high in the ArcN neurons from the 17th to the 22nd gestational week, then decreases up to the first days after birth and later disappears. Moreover, in eight of the 13 sudden deaths (61%), a hypoplasia of the ArcN was present. In almost all of these cases, EN-2 expression was negative. In conclusion, we support the role of the EN-2 gene in the normal neuronal development and in the anatomic organization of the human ArcN as well as the possible existence of EN-2 mutations related to hypoplasia of this nucleus
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
Histological and biological developmental characterization of the human cerebellar cortex
No full textThe aim of this study was to investigate the histological and biological features of the human cerebellar cortex development and differentiation. We analyzed 52 brains of fetal and infant death victims, aged from 17 gestational weeks to 12th postnatal month. In particular, in the cerebellar cortex at different ages we evaluated, besides the structural aspects, the expression of several biomarkers implicated in proliferative processes (c-fos, PCNA and apoptosis). We observed morphological patterns progressively evolving every month, from the indefinite structure of the second gestational trimester to the four-layered structure (external granular layer, molecular layer, Purkinje cell layer, internal granular layer) of the late fetal cortex and subsequently to the three-layered postnatal definitive morphology, due to involution of the external granular layer. The evaluation of the biological features of the cerebellar cortex showed high proliferative activity mainly confined to the transient external granular layer in prenatal life, and high apoptotic index after birth. Thus, the histological examination, better with the support of biomarker investigations, allows with accuracy to describe the dynamic sequence of steps that occur in human cerebellar cortex development and to establish in each case the age, namely the pre- or postnatal month of life. Consequently, we can diagnose delayed or altered processes of differentiation during the development of the human cerebellar cortex
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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