1,721,260 research outputs found
Occurrence of Olepupuane In Two Mediterranean Nudibranchs - A Protected Form of Polygodial
No full textTumor cells fail to trans-induce telomerase in human umbilical vein endothelial cell cultures
No full textThe shortening of the telomeres that occurs in most somatic cells and untransformed cell cultures is considered a hallmark of cellular senescence. Re-activation of telomerase, which is usually present in immortal cells, avoids telomere shortening and considerably extends the culture life span. Normal human endothelial cells are characterized by an accelerated rate of telomere shortening and reach replicative senescence after a limited number of cell divisions. It has recently been reported that human telomerase reverse transcriptase expression may be strongly up-regulated in human endothelial cells cocultivated with tumor cells. Due to the important implications of this finding on tumor progression, we have extensively analyzed for the presence of telomerase in primary human endothelial cells either cocultivated with tumor cells or grown with tumorconditioned medium. We found modest, but readily detectable, amounts of telomerase in all human endothelial cell cultures analyzed that disappeared as the cultures approached senescence. Quantitative reverse transcription-PCR also showed a direct correlation between human telomerase reverse transcriptase expression and the proliferative index of the cultures. Nevertheless, we did not find any evidence of induction of telomerase activity by tumor cells in any of the tested conditions. All data indicate that telomerase in human endothelial cells follows an activation program that is strictly associated to the culture growth rate
New Propionate-derived Metabolites From Aglaja-depicta and From Its Prey Bulla-striata (opisthobranch, Mollusks)
No full textTwo new polypropionate metabolites aglajne-2 (14) and -3 (2) and the previously known aglajne-1 (1) have been isolated from the opisthobranch mollusc Bulla striata, a prey of the opistobranch Aglaja depicta in which
these compounds were first detected. This finding establishes the dietary origin of these metabolites in A. depicta.
The structures were determined by extensive use of 'H and 13C NMR techniques on the compounds and on their
derivatives and by chemical proofs. Two additional compounds (12 and 13), isolated as racemic diastereoisomers,
are artifacts originating from aglajne-2 (14) during the extraction and purification procedures. The relative and
absolute stereochemistry at C-3 and C-6 of aglajne-1 (1) and -3 (2) has been also determined
Potential Alarm Pheromones From the Mediterranean Opisthobranch Scaphander lignarius
No full textTwo new w-phenyl conjugated trienones, lignarenone-A (2) and lignarenone-B (3), are the main
metabolites isolated from the dorsum acetone extract of Scaphander lignarius. Their structures, closely related
to 3-methyl navenone-B (1) a minor component of the alarm pheromone mixture of the opisthobranch Navonax
inermis, were characterized by spectral methods
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
Two Ichthyotoxic Diacylglycerols From the Opisthobranch Mollusk Umbraculum mediterraneum
No full textTwo ichthyotoxic diacylglycerols, umbraculumin-A (1 ) and -C (2). have been isolated
fron the skin of the opisthobranch mollusc Umbraculum mediterraneum and their
structures determined by spectroscopic means
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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