1,720,964 research outputs found
The renin-angiotensin-aldosterone system and blood pressure during oxprenolol treatment in hypertensive patients pretreated with diuretics.
No full textThe interrelationship between PRA, urinary aldosterone excretion, and blood pressure was studied in 11 patients with essential hypertension while receiving a diuretic (1st week) and subsequently a diuretic + oxprenolol (2nd week). The diuretic reduced blood pressure and body weight but increased PRA and aldosterone. Oxprenolol reduced PRA on the 1st day but to a lesser extent on the 7th day. Blood pressure was decreased 1 day after oxprenolol administration, but to a greater extent on the 7th day. Blood pressure decrements were independent of renin suppression, but directly correlated to aldosterone changes. These data suggest that the hypotensive effect of oxprenolol in patients receiving diuretic treatment is independent of its suppression of renin. Aldosterone suppression may instead contribute to the hypotensive effect of the drug
Female normoprolactinaemic infertility: a poorly defined clinical disturbance, a possible physiopathological mechanism, an effective regimen therapy.
No full textDopaminergic (DA2) receptors and renal circulation in normotensive subjects and in patients with essential hypertension.
No full textThe effect of clonidine on renin and aldosterone of hypertensive patients.
No full textThe behaviour of blood pressure, sodium balance, plasma potassium, urinary and plasma aldosterone, plasma cortisol, growth hormone, 17 OH ketogenic steroids were studied in 20 mild hypertensive in-patients (10 with low and 10 with normal PRA) before, 1 day and 5 days after clonidine. Blood pressure was significantly decreased by clonidine while PRA was as a mean unchanged. No correlation was found between blood pressure changes and either basal PRA or aldosterone values or PRA and aldosterone changes after clonidine. Urinary aldosterone was significantly decreased by clonidine and aldosterone changes were unrelated to those parameters (PRA, plasma potassium, sodium balance, ACTH) which are known to influence aldosterone secretion, while GH showed a small increment the first day but was unchanged the fifth day. Plasma aldosterone was not significantly changed by clonidine but its changes showed an inverse correlation to urinary aldosterone changes. Conclusions: In our normal and low renin patients the antihypertensive action of clonidine is neither predicted by basal PRA and urinary aldosterone values nor explained by their changes. The opposite effect of clonidine on urinary aldosterone and plasma aldosterone may point to a decrease of metabolic clearance rate of the hormone exerted by the drug
Vascular renin-angiotensin system and neurotransmission in hypertensive persons.
No full textThe existence of a vascular renin-angiotensin system and its role in modulating sympathetic activity were evaluated in forearm arterioles of hypertensive individuals. Isoproterenol (0.03, 0.01, 0.3 μg/100 ml/min for 5 minutes each; n=5) was infused into the brachial artery, and active and inactive renin, angiotensin II, and norepinephrine forearm balance (venous-arterial differences corrected for forearm blood flow by strain-gauge plethysmography) were measured. Isoproterenol caused vasodilation and a dose-dependent active and inactive renin, angiotensin II, and norepinephrine outflow, an effect blunted by propranolol (10 μg/100 ml/min). To evaluate the role of local angiotensin II on β-mediated norepinephrine overflow, the experiment was repeated with captopril (2.5 μg/100 ml/min for 10 minutes; n=5), which abolished angiotensin II release and significantly reduced norepinephrine overflow. To test whether angiotensin II facilitates both prejunctional norepinephrine release and its postjunctional action, we evaluated the effect of exogenous angiotensin II, infused into the brachial artery at low concentrations (0.001 μg/100 ml/min), on forearm vasoconstriction and norepinephrine release induced by endogenous sympathetic activation (application of a lower body negative pressure: -10 and -20 mm Hg for 5 minutes, n=10) and on the vasoconstrictor effect of local norepinephrine (0.0015, 0.005, 0.015, 0.05, 0.15 μg/100 ml/min for 3 minutes each; n=6). Although angiotensin II increased the vasoconstricting effect and the norepinephrine release induced by lower body negative pressure, it failed to affect norepinephrine-mediated vasoconstriction. Our data indicate the existence in hypertensive individuals of a vascular renin-angiotensin system that seems to modulate sympathetic activity through the presynaptic facilitation of norepinephrine release
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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