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Mellet (S.), Joffre (M.-D.) & Serbat (G.). Grammaire fondamentale du latin. Le signifié du verbe.
No full textMawet Francine. Mellet (S.), Joffre (M.-D.) & Serbat (G.). Grammaire fondamentale du latin. Le signifié du verbe.. In: Revue belge de philologie et d'histoire, tome 79, fasc. 1, 2001. Antiquité - Oudheid. pp. 241-242
Mellet (S.), Joffre (M.-D.) & Serbat (G.). Grammaire fondamentale du latin. Le signifié du verbe.
No full textMawet Francine. Mellet (S.), Joffre (M.-D.) & Serbat (G.). Grammaire fondamentale du latin. Le signifié du verbe.. In: Revue belge de philologie et d'histoire, tome 79, fasc. 1, 2001. Antiquité - Oudheid. pp. 241-242
Le calcium bloque une conductance potassique de repos et active des conductances potassiques sensibles à l'apamine et à l'ibériotoxine, dans la cellule de Leydig du testicule de rat mature.
No full textEffect of cyclic AMP on the calcium-dependent potassium conductances of rat Leydig cells
No full textTwo potassium conductances have been isolated in rat Leydig cells by their sensitivity to cytosolic calcium and to K+ channel blockers. We used the whole-cell configuration of the patch-clamp technique to investigate their sensitivity to cyclic AMP, the main messenger of luteinizing hormone, which stimulates Leydig cell steroidogenesis. The voltage-dependent potassium conductance is not modified by exposing the cell to 1 mM chlorophenylthio-cyclic AMP (CPT-cAMP), a membrane-permeant analogue of cAMP. By contrast, the large, calcium-activated potassium conductance is upregulated by CPT-cAMP. Furthermore, the latter is potentiated by the chloride channel blocker 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid, sodium salt (SITS)
Modulation of K+ conductances by Ca2+ and human chorionic gonadotrophin in Leydig cells from mature rat testis
No full text1. Although 12 the control of steroidogenic activity of the Leydig cell by the peptides luteinizing hormone (LK) and human chorionic gonadotrophin (hCG) is clearly mediated by cAMP, the extent to which Ca2+ controls the Leydig cell function is less well defined. In the present study, the whole-cell configuration of the patch-clamp technique was used to investigate the modulation of potassium conductances by calcium and hCG, in the Leydig cells from mature rat testis.
2. In symmetrical glutamate solutions, depolarizations elicited outwardly rectifying currents, which were mainly carried by potassium and were blocked by tetraethylammonium and 4-aminopyridine, for values of [Ca2+](i) below 10(-8) M, transient currents of low amplitudes, insensitive to charybdotoxin (CTX) and iberiotoxin (IBTX), mere activated above -40 mV. For [Ca2+](i) values of 10(-7) M and above, noisy currents with slow activation kinetics were activated above 0 mV. These currents were sustained and were sensitive to CTX and IBTX.
3. Both current types were modulated by intracellular calcium. Ionomycin and a [Ca2+](i) elevation in the range from 10(-9) to 10(-7) M, both inhibited the CTX-insensitive currents, whereas a rise in the calcium concentration above 10(-7) M increased the amplitude and shifted the threshold of activation of the CTX-sensitive currents to less positive levels.
4. hCG (1-50 in, ml(-1)), in conditions where the chloride currents were strongly inhibited by 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS), induced a partial inhibition of the CTX-insensitive currents but was unable to increase the CTX-sensitive currents
5. No voltage-sensitive calcium current was recorded in control or hCG-stimulated cells.
6. The results indicate that hCG inhibits one kind of Ca2+ modulated channel, perhaps as a result of a moderate [Ca2+](i) rise, but is unable to increase the intracellular Ca2+ concentration to the range in which large conductance Ca2+-dependent channels are activated
Inhibitory effect of internal sodium and Hepes on the voltage-dependent potassium conductance of rat Leydig cells
No full textWe used the whole-cell configuration of the patch-clamp technique to investigate modulation of the voltage-dependent K+ conductance of rat Leydig cells by intracellular pH, Hepes, and Na+. pH (range 6.8-7.4) has no effect on current. Removal of Na+ (from 10 to 0 mM) increases the amplitude of K+ current and abolishes the plateau effect on peak current. Reduction of Hepes (from 25 to 10 mM) increases the amplitude of K+ current and, simultaneously, shifts the threshold for current activation to the left, but the plateau of current is still present. Removal of Na+ cancels the potentiating effect of Hepes on frequency of occurrence of time-dependent inactivation of K+ current. We conclude that the blocking effect of Hepes and Na+ on K+ current may presumably involve two distinct mechanisms, but we can not exclude some cooperativity in their ability to inactivate the voltage-gated potassium conductance of rat Leydig cell
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
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