1,720,965 research outputs found
Inhibitors of ADP-ribosyl transferase suppress the mitogenic actions exerted by tumour promoters, but not those evoked by peptide mitogens, in primary neonatal rat hepatocytes
No full textA significant stimulation of the 24-h (between day 4 and 5 in vitro) new DNA synthetic activity was elicited in primary neonatal rat hepatocytes kept in low-calcium (0.01 mmol/l) HiWoBa2000 synthetic medium by the addition of a single dose (10(-10) mol/l) of each of several tumour promoters [i.e. 12-O-tetradecanoylphorbol-13-acetate (TPA), phenobarbital, nafenopin, saccharin, teleocidin, benzoyl peroxide butylhydroxytoluene (BHT), dichlorodiphenyltrichloroethane (DDT), lindane, clofibrate and melittin]. Even hormones [e.g. epidermal growth factor (EGF), glucagon and insulin at 10(-10) mol/l] and EGF-like acting drugs (i.e. imidazole and indomethacin, at 10(-11) mol/l) similarly enhanced with respect to untreated controls the 24-h flow into S phase of the primary hepatocytes on condition, however, that the cells were incubated in a high- (i.e. 1.8 mmol/l) and not a low-calcium HiWoBa2000 medium. Xenobiotics, peptide mitogens and EGF-like acting drugs also enhanced the in vitro hepatocellular mitotic activity. The growth-stimulatory effects of the aforementioned eleven tumour promoters were entirely suppressed by the simultaneous addition to the growth medium of a fully effective dose (10(-4) - 10(-3) mol/l) of agents, such as 3-aminobenzamide (3-ABA), 3-methoxybenzamide (3-MBA) or nicotinamide (NA), that are known to inhibit the activity of ADP-ribosyl transferase (ADPRT). However, under the same conditions these inhibitors hampered neither the basal DNA synthetic and mitotic activities of spontaneously cycling hepatocytes nor the stimulation of the hepatocellular growth processes evoked by peptide mitogens and EGF-like acting drugs. Quantitative autoradiographic investigations showed that the incorporation of the ADP-ribose precursor and ADPRT substrate [3H]NAD into nuclear macromolecules of gently digitonin-permeabilized hepatocytes was negligible in the untreated cultures, whereas it was strikingly and nearly steadily increased by a 2-, 8- and 24-h exposure to a fully mitogenic dose (10(-10) mol/l) of TPA, thereby revealing that an early, significant and roughly steady activation of the nuclear ADPRT had taken place in the phorbol ester-treated liver parenchymal cells. The simultaneous addition of 3-ABA (10(-4) mol/l) not only fully checked the mitogenic effects of TPA, but even suppressed about two-thirds of the TPA-elicited nuclear incorporation of [3H]NAD by the permeabilized hepatocytes, thus showing that a significant curtailment of the TPA-activated ADPRT did occur is association with the abatement of the mitogenic effects of TPA by this inhibitor.(ABSTRACT TRUNCATED AT 400 WORDS
Host blood monocytes play an important role, both by themselves and interacting with allo-Langerhans cells, in presenting allo-epidermal cell antigens in vitro.
No full textHost blood monocytes play an important role, both by themselves and interacting with allo-Langerhans cells, in presenting allo-epidermal cell antigens in vitro
PTH1-34 induces the differentiation program in adult human keratinocytes cultured in MCDB 153 medium.
No full textPTH1-34 induces the differentiation program in adult human keratinocytes cultured in MCDB 153 medium
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
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
Lead ammonium citrate acetate (LACA) greatly enhances the mitogenic effects exerted by hormones in primary adult rat hepatocytes kept in synthetic medium.
No full textLead ammonium citrate acetate (LACA) greatly enhances the mitogenic effects exerted by hormones in primary adult rat hepatocytes kept in synthetic medium
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