1,720,960 research outputs found
The sequential hypothesis on sleep function. II. A correlative study between sleep variables and newly synthesized brain DNA
No full textThe sequential hypothesis on sleep function. I. Evidence that the structure of sleep depends on the nature of the previous waking experience
No full textRole of inwardly-rectifying potassium channels Kir5.1 in learning and memory processes in a mouse knock-out model
No full textA simple method for the DNA content assay of culture maintained pancreatic islets of Langerhans
No full textA simple method for assaying DNA content of in vitro culture maintained pancreatic islets is described. By employing lyophilization of the islets and subsequent fluorometric analysis, we have been able to measure DNA from relatively small cell samples. The method may result advantageous, over others, previously reported, since it is less subject to experiment-related interfering conditions. This procedure, which is easy and reliable, even for very low DNA concentrations, seems to be very useful for culture maintained pancreatic islets, since in vitro work conducted with this endocrine tissue is usually associated with small size cell samples. The method may help for a simple assessment of the viable islet cell mass in in vitro studies
Brain hsp70 expression and DNA damage in mice exposed to extremely low frequency magnetic fields: A dose-response study
No full textPurpose : To determine whether a dose-response relationship
exists among exposure to extremely low frequency magnetic
fi elds (ELF-MF) at diff erent densities and 70-kDa heat shock
protein (hsp70) expression and DNA damage in mouse brain.
Materials and methods : Male CD1 mice were exposed to ELF-MF (50 Hz; 0.1, 0.2, 1 or 2 mT) for 7 days (15 h/day) and sacrificed either at the end of exposure or after 24 h. Hsp70 expression was determined in cerebral cortex-striatum, hippocampus and cerebellum by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot analysis. Primary DNA damage was evaluated in the same tissues by comet assay. Sham-exposed mice were used as controls.
Results : No changes in both hsp70 mRNA and corresponding
protein occurred following exposure to ELF-MF, except for a weak increase in the mRNA in hippocampus of exposed mice to 0.1 mT ELF-MF. Only mice exposed to 1 or 2 mT and sacrifi ced immediately after exposure presented DNA strand breaks higher than controls in all the cerebral areas; such DNA breakage reverted to baseline in the mice sacrifi ced 24 h after exposure.
Conclusions : These data show that high density ELF-MF only
induce reversible brain DNA damage while they do not aff ect
hsp70 expression
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
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