1,720,988 research outputs found
The antihypertensive actions of statins: Modulation by salt intake
Full text linkHydroxy methyl glutaryl CoA inhibitors (statins) are the agents most frequently used to reduce elevated serum cholesterol. In addition to their cholesterol lowering effects, statins also have nonlipid lowering pleiotropic properties. These include reducing oxidative stress, reninangiotensin and endothelin synthesis and activity, and improving nitric oxide (NO) synthesis and availability. Thus, one would predict that statins might be able to exert an antihypertensive effect. Experimental models bear out the blood pressure lowering effects but the data from clinical trials have been inconsistent perhaps due to inappropriate experimental designs, sample size, blood pressure measurement techniques etc. Moreover, although experimental models strongly suggest a role for salt intake in the potential antihypertensive responses to statins, available clinical trials fail to report salt intake in the studied populations. The statins' antihypertensive effects remain an unsettled hypothesis and calls for a large clinical trial at a wide range of doses and a controlled salt intake. Statins meanwhile remain as a excellent option to control high cholesterol and in tissue injury prevention.Fil: Juncos, Luis I.. Fundacion J Robert Cade; ArgentinaFil: Juncos, Luis A.. University of Mississippi; Estados UnidosFil: Garcia, Nestor Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Causas vasculares de hipertensión arterial
No full textFil: García, Nestor Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ciencias de la Salud; Argentina.Fil: García, Nestor Horacio. Universidad Nacional de Córdoba. Facultad de Ciencias Médicas. Instituto de Biología Celuluar; Argentina.Fil: Juncos, Luis Isaías. Fundación Robert Cade; Argentina.La hipertensión renovascular (HTRV) es una forma de hipertensión arterial (HTA) secundaria potencialmente tratable que ocurre con una incidencia aproximada del 1% al 5% entre los pacientes con hipertensión moderada, y del 10% al 45% entre los pacientes con hipertensión severa1-3. Los mecanismos que conducen al desarrollo de hipertensión arterial en esta enfermedad se ponen en marcha cuando se obstruye el flujo de sangre a uno o ambos riñones. Sin embargo, la obstrucción (estenosis), aunque por definición es un requerimiento, no siempre es suficiente para elevar la presión arterial. En efecto, es preciso que la luz vascular se reduzca alrededor de un 60% para que se disparen los fenómenos fisiopatológicos que conducen a la activación del sistema renina-angiotensina-aldosterona, el actor central en la elevación de la presión arterial. Tradicionalmente, la confirmación del diagnóstico se certificaba cuando los valores elevados de presión arterial se corregían después de restablecer el flujo sanguíneo renal. Sin embargo, y en particular en la forma arteriosclerótica, cambios tisulares en el riñón afectado por la estenosis pueden impedir la remisión del cuadro hipertensivo, aun cuando el flujo renal haya sido totalmente restablecido. La interpretación clásica se complica más aún en estos pacientes con estenosis arterioesclerótica, en quienes puede ser muy difícil precisar si la hipertensión resulta de dicha estenosis o es anterior ella.Fil: García, Nestor Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ciencias de la Salud; Argentina.Fil: García, Nestor Horacio. Universidad Nacional de Córdoba. Facultad de Ciencias Médicas. Instituto de Biología Celuluar; Argentina.Fil: Juncos, Luis Isaías. Fundación Robert Cade; Argentina
The protective role of vitamin D on the heart and the kidney
Full text linkFor a long time, vitamin D was regarded as an essential component for the maintenance of appropriate calcium metabolism. Indeed, the calcium-related functions were broadly studied and validated in numerous clinical and epidemiologic studies. All of these vitamin D effects are mediated by a specific receptor. Remarkably, recent investigations show that the vitamin D receptor (VDR) also affects autoimmunity and by these means, the course of neoplasias and tissue inflammation. Moreover, the VDR regulates genes that affect cellular activity including cell differentiation and apoptosis and, by these means, angiogenesis. Actually, vitamin D deficiency has been associated with structural and functional cardiovascular changes that can be reversed by receptor stimulation. In this regard, some of the injurious effects of vitamin D deficiency such as myocardial hypertrophy and high blood pressure seem linked to increased renin-angiotensin activity. Interestingly, chronic renal disease, a condition often associated with greater cardiovascular risk, high blood pressure, myocardial hypertrophy and inappropriate stimulation of the renin angiotensin system, is also tied to inadequate vitamin D activity. In fact, studies in several animal models such as the rat ureteral obstruction model, the 5/6 nephrectomy model and others, clearly show that VDR stimulation prevents both structural and functional changes in the heart and the kidney. Clinical trials are needed to validate the vitamin D potential benefits in chronic kidney disease and its associated cardiovascular risk.Fil: Manucha, Walter Ariel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Juncos, Luis Isaias. Fundación Robert Cade; Argentin
Atorvastatin improves sodium handling and decreases blood pressure in salt-loaded rats with chronic renal insufficiency
Full text linkOxidative stress and inflammation seem to mediate the cardiovascular risks associated with salt sensitivity. Because hydroxymethyl glutaryl coenzyme A reductase inhibitors decrease oxidation and increase nitric oxide (NO) synthesis, we examined the effects of atorvastatin (ator) on tissue injury in rats with a reduced renal mass produced by 5/6 nephrectomy. This salt-sensitive hypertension model causes kidney and cardiovascular injuries. Methods: After undergoing 5/6 nephrectomy or sham surgery, male Sprague-Dawley rats were randomized into five groups: sham, reduced renal mass and a normal salt diet (NNaD), NNaD+ator (50 mg · kg-1 · d-1), reduced renal mass and a high salt diet (HNaD), and HNaD+ator. After assessing the sodium balance for 7 d, we measured blood pressure (BP), creatinemia, proteinuria, nitrites, and 12(S)-hydroxy 5,8,10-heptadecatrienoic acid, the renal cortical expression of endothelial NO synthase, and the ratio of left ventricular weight to body weight. Results: In NNaD rats, creatinine, proteinuria, and 12(S)-hydroxy 5,8,10-heptadecatrienoic acid increased, renal NO indices decreased, but the Na+ balance, BP, and the left ventricular weight/body weight ratio remained unchanged. In the NNaD group, atorvastatin normalized the NO indices and decreased BP and proteinuria, although the remaining parameters continued unchanged. In contrast, HNaD increased creatinemia, proteinuria, and 12(S)-hydroxy 5,8,10-heptadecatrienoic acid excretion rates and decreased renal endothelial NO synthase. Salt retention was accompanied by increased BP and ventricular weight. In this HNaD group, atorvastatin prevented a BP increase, partly decreased sodium retention, but failed to improve NO indices, proteinuria, oxidant stress, and the left ventricular weight/body weight ratio. Atorvastatin exerts beneficial effects on renal function, injury, and salt sensitivity in rats with a reduced renal mass on an NNaD. The HNaD hampers these beneficial effects.Fil: Juncos, Luis Isaias. Fundación J. Robert Cade; Argentina. Universidad Nacional de Córdoba; Facultad de Medicina.; ArgentinaFil: Martín, Fernando L. Mayo Clinic and Foundation; Estados UnidosFil: Baigorria, Sandra T.. Fundación J. Robert Cade; ArgentinaFil: Pasqualini, María Eugenia. Universidad Nacional de Córdoba; Facultad de Medicina.; ArgentinaFil: Fiore, María C.. Fundación J. Robert Cade; ArgentinaFil: Eynard, Aldo Renato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Ciencias de la Salud. Universidad Nacional de Córdoba. Instituto de Investigaciones en Ciencias de la Salud; ArgentinaFil: Juncos, Luis A.. University of Mississippi; Estados UnidosFil: Garcia, Nestor Horacio. Fundación J. Robert Cade; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Ciencias de la Salud. Universidad Nacional de Córdoba. Instituto de Investigaciones en Ciencias de la Salud; Argentin
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
Angiotensin II and Anti Diuretic Hormone exert synergistic effects on thick ascending limb transport in spontaneously hypertensive rats
Full text linkSodium reabsorption is increased in the thick ascending limb (TAL) of Henle in several hypertensive models. In this segment, while transport is increased by ADH via cAMP, sodium reabsorption results from Ang II-induced superoxide (O2-) production. Surprisingly, it is unknown whether these mechanisms overlap in hypertension. We hypothesized that Ang II and ADH have accumulative effects on TAL's transport during hypertension. Methods: The effect of ADH/Ang II in TALs from spontaneously hypertensive rats (SHR) on oxygen consumption (QO2), cAMP and O2- was measured. Results: Basal QO2 was 113.3 ± 14.2 nmol O2/min/mg protein. Addition of ADH (1 nM) increased QO2 by 198%. In the presence of ADH, Ang II (1 nM) elicited a QO2 transient response and then rose to 321.5 ± 28.3 (p = 0.003 vs. ADH). These accumulative effects could be due to nitric oxide synthase (NOS) uncoupling, lower Ang II ability to decrease cAMP or increased O2-. We first measured QO2 using a NOS inhibitor. Pretreatment with L-NAME did not block the observed interaction (p = 0.001 Ang II vs. ADH). Also, Ang II blocked the ADH-stimulated cAMP accumulation in TAL of SHRs. In the presence of ADH, Ang II increased O2- production in TALs from SHR by 309% (p = 0.015 vs. basal). The O2- scavenger tempol blocked the Ang II effects on QO2. In the presence of the NADPH oxidase inhibitor apocynin, the accumulative effects of ADH and Ang II were abolished. We conclude that (1) in SHR, Ang II has accumulative effects on ADH-stimulated transport; (2) this effect is mediated by AT1 receptors, and increased O2- production.Fil: Silva, Guillermo Benjamin. Universidad Nacional de San Juan. Facultad de Ingeniería. Departamento de Electrónica y Automática. Gabinete de Tecnología Médica; ArgentinaFil: Juncos, Luis Isaias. Fundacion J. Robert Cade; ArgentinaFil: Garcia, Nestor Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Ciencias de la Salud. Universidad Nacional de Córdoba. Instituto de Investigaciones en Ciencias de la Salud; Argentin
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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