1,720,958 research outputs found
Supravital exposure to propidium iodide identifies apoptotic cells in the absenceof nucleosomal DNA fragmentation
No full textBy flow cytometry, we have quantitatively evaluated HL-60, MOLT-4, and P815
apoptotic cells induced with camptothecin, staurosporine, and hyperthermia,
respectively. Apoptosis was measured by two different flow cytometry techniques,
using propidium iodide (PI) uptake in permeabilized and nonpermeabilized cells.
Apoptosis also has been analyzed by electron microscopy and DNA cleavage by in
situ nick translation and DNA gel electrophoresis. We demonstrate that supravital
exposure to propidium iodide without prior permeabilization identifies apoptotic
cells, and clearly distinguishes them from necrotic cells in all the cases
examined. This capability is independent of the nucleosomal (180-200 bp)
fragmentation of DNA (which does not take place in MOLT-4 cells), which is the
basis for detection of apoptosis both as a "ladder" by DNA gel electrophoresis
and as a hypodiploid peak by flow cytometry. Therefore, alterations in membrane
permeability, on which PI uptake in living cells is based, allow distinction of
apoptotic cells from necrotic and living cells independently of the heterogeneous
biochemical patterns involved in programmed cell death, which may or may not lead
to DNA oligonucleosomal fragmentation
Cancer of the esophagus - Endoscopic ultrasound: Selection for cure
No full textSeveral treatment options are available to treat esophageal cancer. Ideally, treatment should be individualized, based on the projected treatment outcome for that individual. Accurate staging of the extent of the disease at the time of diagnosis offers the most rational attempt at stratifying patients into categories that can be used to affect treatment choices. Endoscopic ultrasonography (EUS) is the most accurate nonoperative technique for determining the depth of tumour infiltration and thus is accurate in predicting which patients will be able to undergo complete resection. EUS is also being used for tumour staging in order to guide treatment decisions in patients with esophageal cancer
Anti-BrdUrd labeling of newly synthesized DNA in HL-60 cells triggered to apoptosis.
Full text linkApoptosis is an active process that takes place dur-
ing pre- and postnatal life. It can be viewed as the
essential counterpart to cell proliferation, both phe-
nomena being aimed at the maintenance of tissue
and organ homeostasis. Because apoptosis often
takes place during the S phase of the cell cycle, we
describe the spatial and temporal correlation be-
tween DNA synthesis and DNA cleavage taking place
in the same nucleus at the same time as a result of
the action of camptothecin on proliferating HL-60
cells in vitro. The relationship between DNA syn-
thesis and DNA fragmentation was studied at the
single-cell level by bromodeoxyuridine (BrdUrd)
incorporation revealed by flow cytometry, electron
microscopy, and confocal microscopy. Most HL-60
cells are triggered to apoptosis during the first hour
of treatment with camptothecin, and only cells in
early-middle S phase are sensitive to the drug effect,
whereas late S phase cells appear insensitive to
camptothecin-induced apoptosis. Our data, there-
fore, reinforce the hypothesis of a DNA strand break
threshold that may exist in the cell, beyond which
the apoptotic program is activated. Moreover, DNA
synthesis activity in the nucleus committed to apop-
tosis is gradually downregulated; after 6 h of camp-
tothecin treatment, virtually no residual DNA repli-
cation activity can be detected in micronuclei. DNA
repair does not appear to be involved in bromode-
oxyuridjne incorporation during the apoptotic pro-
CeSS
Anti-BrdUrd labeling of newly synthesized DNA in HL-60 cells triggered toapoptosis
No full textApoptosis is an active process that takes place during pre- and postnatal life.
It can be viewed as the essential counterpart to cell proliferation, both
phenomena being aimed at the maintenance of tissue and organ homeostasis. Because
apoptosis often takes place during the S phase of the cell cycle, we describe the
spatial and temporal correlation between DNA synthesis and DNA cleavage taking
place in the same nucleus at the same time as a result of the action of
camptothecin on proliferating HL-60 cells in vitro. The relationship between DNA
synthesis and DNA fragmentation was studied at the single-cell level by
bromodeoxyuridine (BrdUrd) incorporation revealed by flow cytometry, electron
microscopy, and confocal microscopy. Most HL-60 cells are triggered to apoptosis
during the first hour of treatment with camptothecin, and only cells in
early-middle S phase are sensitive to the drug effect, whereas late S phase cells
appear insensitive to camptothecin-induced apoptosis. Our data, therefore,
reinforce the hypothesis of a DNA strand break threshold that may exist in the
cell, beyond which the apoptotic program is activated. Moreover, DNA synthesis
activity in the nucleus committed to apoptosis is gradually downregulated; after
6 h of camptothecin treatment, virtually no residual DNA replication activity can
be detected in micronuclei. DNA repair does not appear to be involved in
bromode-oxyuridine incorporation during the apoptotic process
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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