1,721,010 research outputs found
Transcription of AML1 in hematopoietic subfractions of normal adults
No full textThe transcription factor AML1 (CBFA2) is indispensable for early fetal hematopoiesis, but also transactivates target genes which are important for further downstream hematopoiesis. However, little is known about the impact of AML1 on lineage-committed stages. We investigated the transcription of AML1 in subfractions of four normal adult bone marrow aspirates isolated by fluorescence-activated cell sorting. AML1 is transcribed in early (CD34+/CD38-) and late (CD34+/CD38+) hematopoietic progenitors, B-cell precursors (CD10+/CD19+) as well as in immature monocytes (CD14-/CD11c+), myeloid (CD15+/CD33+ and CD15+/CD33-) and erythroid (GPA+/CD3-/CD45-) cells, but not in T lymphocytes (GPA-/CD3+/CD45+). These data suggest that in adult hematopoiesis AML1 may be critically involved in differentiation of early hematopoietic progenitors, erythroid cells, and lymphoid precursors. These subfractions are interesting targets to study the importance of AML1 in definitive hematopoiesis
TGF-beta and its receptor complex in leukemic B-cell precursors
No full textTransforming growth factor beta (TGF-beta) is a highly conserved peptide with growth-inhibitory activity in multiple normal and transformed cell types. Signal transduction is mediated through the receptor complex, consisting of two active seronine or threonine kinases (TGF-beta-receptor I and II) and the receptor-associated proteins betaglycan (TGF-beta-receptor III) and endoglin. In this study, we assessed the analysis of the role of TGF-beta and the transcription of the genes for TGF-beta and its receptor in highly purified leukemic B-cell precursors (BCPs) of patients with common acute lymphoblastic leukemia (cALL). Leukemic BCPs were positive for gene transcription of TGF-beta (9/9), the TGF-beta-receptor I (9/9), the TGF-beta-receptor II (6/6), betaglycan (5/6), and endoglin (6/6). Incubation with TGF-beta significantly reduced the cell viability of leukemic BCPs by a mean of 45% (p = 0.0009). The reduction of cell viability was associated with the induction of apoptosis by a mean of 31%. TGF-beta caused significant suppression of the S phase (p = 0.002) and accumulation in the G0/G1 phase (p = 0.0005). It also reduced expression of the adhesion surface receptor CD18 and the Fas antigen CD95 from 58% to 40% and from 48% to 27%, respectively. The data indicate that TGF-beta is a negative growth signal in leukemic BCPs and point to an additional role of TGF-beta as an immunomodulatory cytokine, suggesting a complex role of TGF-beta in the leukemogenesis of cALL
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
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