1,720,972 research outputs found
Effect of normobaric hyperoxia on leukemic cell lines in vitro
No full textAims and Objectives: The objective of this study was to evaluate the molecular mechanisms following normobaric hyperoxia on acute lymphoblastic leukemic cell lines in vitro through assessment of oxidative stress, DNA-fragmentation, mitochondrial function and apoptosis induction. The study was aiming for a more detailed understanding of the basic molecular alterations in leukemic cells induced by reactive oxygen species. Methods: Acute lymphoblastic leukemic cell lines Jurkat and CCRF-SB were cultured according to standard operating procedures and exposed to a single bout of 65% oxygen for 2 or 18 hours respectively. The oxygen exposure protocol included a control sample before exposure, measurements immediately after exposure and after recovery intervals of 6 hours and 24 hours in normoxic conditions. DNA-fragmentation was assessed using single cell gel electrophoresis (comet assay), protein expression of oxidative stress markers, induction of nitric oxide Synthases and expression of pro- and anti-apoptotic proteins were assessed using western blot, electrophoretic mobility shift assay, or enzyme-linked immunosorbent assay. High-resolution respirometry was applied for measurement of mitochondrial respiratory capacity and complex activity within the electron transfer system. Results: The level of oxidative stress in both cell lines was increased after normobaric hyperoxia, the B-cell with a an immediate response after exposure but fast recovery and the T-cell with a delayed response up to 24 hours after the stimulus. Mitochondrial impairment of the intact cells could not be found, however, changes in the activities of complexes I and II were discovered after hyperoxia compared to normoxic conditions. Apoptosis induction and regulation of nitric oxide synthase expression was solely found in the T-cell. Discussion: Oxidative stress was induced with 65% oxygen in both cell lines and with both exposure schemes. However, molecular and metabolic reactions to reactive oxygen species in B- and T-cells varied greatly. While the B-cell was affected immediately but recovered within 24 hours and only showed a transient activation of apoptotic pathways, the T-cell responded later with DNA-fragmentation, apoptosis induction after long-term exposure, and regulation of nitric oxide synthase expression. Conclusion: Looking at the very different effects of normobaric oxygen on molecular and metabolic alterations in the two cell lines examined, it does seem inadequate to propose a general oxygen exposure scheme for acute lymphocytic leukemia. Sensitisation of each cell line will have to be considered individually. Additional research is needed to separately identify suitable intervals for each cell line before ex vivo or animal experiments can be initiated
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Hyperoxia Alters Ultrastructure and Induces Apoptosis in Leukemia Cell Lines.
No full textOxygenation conditions are crucial for growth and tumor progression. Recent data suggests a decrease in cancer cell proliferation occurring after exposure to normobaric hyperoxia. Those changes are associated with fractal dimension. The purpose of this research was to study the impact of hyperoxia on apoptosis and morphology of leukemia cell lines. Two hematopoietic lymphoid cancer cell lines (a T-lymphoblastoid line, JURKAT and a B lymphoid line, CCRF-SB) were tested under conditions of normobaric hyperoxia (FiO2 > 60%, ± 18h) and compared to a standard group (FiO2 = 21%). We tested for apoptosis using a caspase-3 assay. Cell morphology was evaluated by cytospin, microphotography after coloration, and analysis by a fractal dimension calculation software. Our results showed that exposure of cell cultures to transient normobaric hyperoxia induced apoptosis (elevated caspase-3) as well as significant and precocious modifications in cell complexity, as highlighted by increased fractal dimensions in both cell lines. These features are associated with changes in structure (pycnotic nucleus and apoptosis) recorded by microscopic analysis. Such morphological alterations could be due to several molecular mechanisms and rearrangements in the cancer cell, leading to cell cycle inhibition and apoptosis as shown by caspase-3 activity. T cells seem less resistant to hyperoxia than B cells.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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