993 resultados para Función ventricular


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Con la entrada en vigencia de la Constitución del 2008 en lo concerniente a la organización de la administración de justicia. se dio un giro radical, pues se impuso el nacimiento de una nueva Función Judicial acorde a la nueva concepción del Estado. Este cambio radical daría lugar para que el legislativo dicte una ley que establece los principios, sienta las bases de la organización de los diferentes organismos que integran la Función Judicial, concebida como una unidad, y determina las normas a las cuales han de someter su actuación quienes intervienen en el proceso judicial. El ejercicio de la potestad sancionadora reconocida constitucionalmente y el reconocimiento del poder para el establecimiento de sanciones a determinadas conductas consideradas como lesivas al ordenamiento jurídico, son unos de los asuntos que también se desarrollan en el Código Orgánico de la Función Judicial. Y es a partir del análisis de esas normas, de la doctrina y la jurisprudencia que pretendo determinar con mi estudio los rasgos esenciales que definen el ejercicio de la potestad sancionatoria disciplinaria del órgano de control de la Función Judicial y establecer si el procedimiento administrativo sancionador previsto en el Código Orgánico funciona en estricta observancia de los derechos y garantías previstos en la Constitución de la República, particularmente en lo concerniente al principio de proporcionalidad, en cuanto se trata de un principio que permite evitar los excesos o abusos de poder que podrían provenir del empleo indiscriminado de la facultad discrecional atribuida al órgano de control y garantizar que exista una debida proporcionalidad entre la gravedad de la falta y la sanción impuesta. En otras palabras, el objetivo de esta tesis es realizar un análisis dogmático y normativo del ejercicio de la potestad sancionadora disciplinaria del órgano de control de la Función Judicial y su sujeción al principio de proporcionalidad. Para tal efecto, he realizado una tarea de recopilación y análisis de algunos textos doctrinarios en materia administrativa, entre los que juegan un rol preponderante las elaboraciones de Carlos Bernal Pulido, Juan Carlos Casaggne, Javier Vidal Perdomo, los mismos que por su precisión técnica, me han proporcionado una clara orientación para mi estudio.

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Este trabajo investigativo denominado la función del fiduciario, su responsabilidad y alcance en la figura del fideicomiso mercantil de garantía presenta una visión real respecto al verdadero papel que debe cumplir el fiduciario durante todo el proceso de constitución y ejecución de un fideicomiso mercantil de garantía; dicha función incluye el análisis de la responsabilidad del fiduciario y su alcance dentro de esta modalidad de fideicomiso. El objetivo principal de esta tesis es brindar a sus lectores ciertos parámetros generales y específicos respecto a las consecuencias del actuar del fiduciario en el fideicomiso mercantil de garantía. El alcance de esta investigación consiste en un estudio del fideicomiso mercantil de garantía que va desde una orientación teórica (antecedentes del fideicomiso, conceptos básicos y análisis legal del fideicomiso) hasta el estudio de un caso práctico (análisis de la estructuración legal de un contrato de fideicomiso mercantil de garantía) para llegar a plantear criterios que permitan establecer cuál es la responsabilidad del fiduciario y el alcance de la misma en este tipo de fideicomisos. Sin duda, dentro de esta investigación se utilizan métodos deductivos e inductivos, así como herramientas normativas, ya que; dentro de esta investigación fue necesario analizar las nuevas reformas legales establecidas en el año 2014 para el fideicomiso mercantil de garantía, las cuales delimitaron en cierta forma la aplicación de esta figura en el Ecuador. Con el análisis de las reformas legales, se concluye como se puede utilizar esta figura legal en Ecuador y cuáles son las desventajas que se generaron en esta modalidad de fideicomiso a partir de dichas reformas. Finalmente, la tesis brinda un aporte para los sujetos intervinientes del contrato de fideicomiso mercantil de garantía en lo que respecta a: las obligaciones; su responsabilidad; alcance y; función que como sujeto activo tiene el fiduciario en este tipo de contratos y que en ciertos casos constituye una responsabilidad de medio pero en otros casos es una responsabilidad de resultados.

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Previous studies have shown that "Mudanpi", a Chinese herbal medicine, has a significant cardioprotective effect against myocardial ischaemia. Based on these findings we hypothesised that paeonol, the main component of Mudanpi, might have an effect on the cellular electrophysiology of cardiac ventricular myocytes. The effects of paeonol on the action potential and ion channels of cardiac ventricular myocytes were studied using the standard whole-cell configuration of the patch-clamp technique. Ventricular myocytes were isolated from the hearts of adult guinea-pig by enzymic dispersion. The myocytes were continuously perfused with various experimental solutions at room temperature and paeonol applied in the perfusate. Action potentials and membrane currents were recorded using both current and voltage clamp modes of the patch-clamp technique. Paeonol, at concentrations 160 mu M and 640 mu M, decreased the action potential upstroke phase, an action associated with the blockade of the voltage-gated, fast sodium channel. The effects of paeonol on both action potential and Na+ current were concentration dependent. Paeonol had a high affinity for inactivated sodium channels. Paeonol also shortened the action potential duration, in a manner not associated with the blockade of the calcium current, or the enhancement of potassium currents. These findings suggest that paeonol, and therefore Mudanpi, may possess antiarrhythmic activity, which may confer its cardioprotective effects. (c) 2006 Elsevier B.V All rights reserved.

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We have identified and characterised a cDNA encoding a novel gene, designated myocyte stress 1 (ms1), that is up-regulated within 1 h in the left ventricle following the application of pressure overload by aortic banding in the rat. The deduced ms1 protein of 317 amino acids contains several putative functional motifs, including a region that is evolutionarily conserved. Distribution analysis indicates that rat ms1 mRNA expression is predominantly expressed in striated muscle and progressively increases in the left ventricle from embryo to adulthood. These findings suggest that rust may be important in striated muscle biology and the development of pressure-induced left ventricular hypertrophy. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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The molecular mechanisms responsible for the alterations in proliferative capacity of cardiac myocytes during development remain unknown; however, cell cycle dependent molecules may be involved. We have determined the expression of cyclins A, D1–3and E, and cyclin-dependent kinases (CDKs) 2, 4, 5 and 6 and cdc2 in freshly isolated rat cardiac myocytes from fetal (18 days gestation), neonatal (2 days post-natal) and adult animals by immunoblotting. Our results show a dramatic decrease in expression of these proteins during normal cardiac development, such that levels are highest in fetal myocytes but are significantly down-regulated in adult cells (P<0.05, in each case). We also have determined thein vitrokinase activities of cdc2, CDK2, CDK4, CDK5 and CDK6 immunocomplexes in fetal, neonatal and adult myocytes. There was a consistent and significant loss of cdc2, CDK2, CDK4 and CDK6 kinase activities in adult cardiac cell lysates (5.3-, 10.6-, 1.5- and 1.9-fold decreases, respectively) when compared to neonatal samples (P<0.05); CDK5 activity showed a similar trend but failed to reach significance. In conclusion, our results show that the expression and activities of various positive regulators of the cell cycle are down-regulated significantly during development of the cardiac myocyte, concomitant with the loss of proliferative capacity in adult myocytes. Down-regulation of these proteins may be pivotal in the withdrawal of the cardiac myocyte from the cell cycle.

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The translocation of protein kinase C (PKC) isoforms PKC-alpha, PKC-delta, PKC-epsilon, and PKC-zeta from soluble to particulate fractions was studied in ventricular cardiomyocytes cultured from neonatal rats. Endothelin-1 (ET-1) caused a rapid ETA receptor-mediated translocation of PKC-delta and PKC-epsilon (complete in 0.5-1 min). By 3-5 min, both isoforms were returning to the soluble fraction, but a greater proportion of PKC-epsilon remained associated with the particulate fraction. The EC50 of translocation for PKC-delta was 11-15 nM ET-1 whereas that for PKC-epsilon was 1.4-1.7 nM. Phenylephrine caused a rapid translocation of PKC-epsilon (EC50 = 0.9 microM) but the proportion lost from the soluble fraction was less than with ET-1. Translocation of PKC-delta was barely detectable with phenylephrine. Neither agonist caused any consistent translocation of PKC-alpha or PKC-zeta. Activation of p42 and p44 mitogen-activated protein kinase (MAPK) by ET-1 or phenylephrine followed more slowly (complete in 3-5 min). Phosphorylation of p42-MAPK occurred simultaneously with its activation. The proportion of the total p42-MAPK pool phosphorylated in response to ET-1 (50%) was greater than with phenylephrine (20%). In addition to activation of MAPK, an unidentified p85 protein kinase was activated by ET-1 in the soluble fraction whereas an unidentified p58 protein kinase was activated in the particulate fraction.

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The involvement of pertussis toxin (PTX)-sensitive and -insensitive pathways in the activation of the mitogen-activated protein kinase (MAPK) cascade was examined in ventricular cardiomyocytes cultured from neonatal rats. A number of agonists that activate heterotrimeric G-protein-coupled receptors stimulated MAPK activity after exposure for 5 min. These included foetal calf serum (FCS), endothelin-1 (these two being the most effective of the agonists examined), phenylephrine, endothelin-3, lysophosphatidic acid, carbachol, isoprenaline and angiotensin II. Activation of MAPK and MAPK kinase (MEK) by carbachol returned to control levels within 30-60 min, whereas activation by FCS was more sustained. FPLC on Mono Q showed that carbachol and FCS activated two peaks of MEK and two peaks of MAPK (p42MAPK and p44MAPK). Pretreatment of cells with PTX for 24 h inhibited the activation of MAPK by carbachol, FCS and lysophosphatidic acid, but not that by endothelin-1, phenylephrine or isoprenaline. Involvement of G-proteins in the activation of the cardiac MAPK cascade was demonstrated by the sustained (PTX-insensitive) activation of MAPK (and MEK) after exposure of cells to AlF4-. AlF4- activated PtdIns hydrolysis, as did endothelin-1, endothelin-3, phenylephrine and FCS. In contrast, the effect of lysophosphatidic acid on PtdIns hydrolysis was small and carbachol was without significant effect even after prolonged exposure. We conclude that PTX-sensitive (i.e. Gi/G(o)-linked) and PTX-insensitive (i.e. Gq/Gs-linked) pathways of MAPK activation exist in neonatal ventricular myocytes. FCS may stimulate the MAPK cascade through both pathways.

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The expression of protein kinase C (PKC) isoforms (PKC-alpha, PKC-beta 1, PKC-delta, PKC-epsilon, and PKC-zeta) was studied by immunoblotting in whole ventricles of rat hearts during postnatal development (1-26 days) and in the adult. PKC-alpha, PKC-beta 1, PKC-delta, PKC-epsilon, and PKC-zeta were detected in ventricles of 1-day-old rats, although PKC-alpha and PKC-beta 1 were only barely detectable. All isoforms were rapidly downregulated during development, with abundances relative to total protein declining in the adult to < 25% of 1-day-old values. PKC-beta 1 was not detectable in adult ventricles. The specific activity of PKC was also downregulated. The rat ventricular myocyte becomes amitotic soon after birth but continues to grow, increasing its protein content 40- to 50-fold between the neonate and the 300-g adult. An important question is thus whether the amount of PKC per myocyte is downregulated. With the use of isolated cells, immunoblotting showed that the contents per myocyte of PKC-alpha and PKC-epsilon increased approximately 10-fold between the neonatal and adult stages. In rat ventricles, the rank of association with the particulate fraction was PKC-delta > PKC-epsilon > PKC-zeta. Association of these isoforms with the particulate fraction was less in the adult than in the neonate. In primary cultures of ventricular myocytes prepared from neonatal rat hearts, 1 microM 12-O-tetradecanoylphorbol-13-acetate (TPA) elicited translocation of PKC-alpha, PKC-delta, and PKC-epsilon from the soluble to the particulate fraction in < 1 min, after which time no further translocation was observed. Prolonged exposure (16 h) of myocytes to 1 microM TPA caused essentially complete downregulation of these isoforms, although downregulation of PKC-epsilon was slower than for PKC-delta. In contrast, PKC-zeta was neither translocated nor downregulated by 1 microM TPA. Immunoblotting of human ventricular samples also revealed downregulation of PKC relative to total protein during fetal/postnatal development.

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In ventricular myocytes cultured from neonatal rat hearts, bradykinin (BK), kallidin or BK(1-8) [(Des-Arg9)BK] stimulated PtdinsP2 hydrolysis by 3-4-fold. EC50 values were 6 nM (BK), 2 nM (kallidin), and 14 microM [BK(1-8)]. BK or kallidin stimulated the rapid (less than 30 s) translocation of more than 80% of the novel protein kinase C (PKC) isoforms nPKC-delta and nPKC-epsilon from the soluble to the particulate fraction. EC50 values for nPKC-delta translocation by BK or kallidin were 10 and 2 nM respectively. EC50 values for nPKC-epsilon translocation by BK or kallidin were 2 and 0.6 nM respectively. EC50 values for the translocation of nPKC-delta and nPKC-epsilon by BK(1-8) were more than 5 microM. The classical PKC, cPKC-alpha, and the atypical PKC, nPKC-zeta, did not translocate. BK caused activation and phosphorylation of p42-mitogen-activated protein kinase (MAPK) (maximal at 3-5 min, 30-35% of p42-MAPK phosphorylated). p44-MAPK was similarly activated. EC50 values for p42/p44-MAPK activation by BK were less than 1 nM whereas values for BK(1-8) were more than 10 microM. The order of potency [BK approximately equal to kallidin > BK (1-8)] for the stimulation of PtdInsP2 hydrolysis, nPKC-delta and nPKC-epsilon translocation, and p42/p44-MAPK activities suggests involvement of the B2 BK receptor subtype. In addition, stimulation of all three processes by BK was inhibited by the B2BK receptor-selective antagonist HOE140 but not by the B1-selective antagonist Leu8BK(1-8). Exposure of cells to phorbol 12-myristate 13-acetate for 24 h inhibited subsequent activation of p42/p44-MAPK by BK suggesting participation of nPKC (and possibly cPKC) isoforms in the activation process. Thus, like hypertrophic agents such as endothelin-1 (ET-1) and phenylephrine (PE), BK activates PtdInsP2 hydrolysis, translocates nPKC-delta, and nPKC-epsilon, and activates p42/p44-MAPK. However, in comparison with ET-1 and PE, BK was only weakly hypertrophic as assessed by cell morphology and patterns of gene expression. This difference could not be attributed to dissimilarities between the duration of activation of p42/p44-MAPK by BK or ET-1. Thus activation of these signalling pathways alone may be insufficient to induce a powerful hypertrophic response.

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The p21-activated protein kinases (PAKs) may participate in signalling from Cdc42/Rac1 to the stress-regulated MAPKs (SAPKs/JNKs and p38-/HOG-1-related-MAPKs). We characterized the expression and regulation of alpha PAK in cultured ventricular myocytes. alpha PAK was specifically immunoprecipitated from myocyte extracts. High basal alpha PAK activity was detected in unstimulated myocytes. Its activity was increased rapidly (<30 s) by hyperosmotic shock in the presence of okadaic acid, and was maximal by 3 min (187 +/- 7% relative to unstimulated cells). Endothelin-1 and interleukin-1beta, which also activate SAPKs/JNKs, did not increase alpha PAK activity and presumably act through different PAK isoforms or other mechanisms.

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The physiological activator of protein kinase C (PKC), diacylglycerol, is formed by hydrolysis of phosphoinositides (PI) by phospholipase C (PLC) or phosphatidylcholine by phospholipase D (PLD). We have measured activation of these phospholipases by endothelin-1 (ET-1), bradykinin (BK), or phenylephrine (PE) in ventricular myocytes cultured from neonatal rat. The stimulation of PI hydrolysis after 10 min by 0.1 microM ET-1 (about 12-fold) was much greater than for BK or PE (each about four-fold), and did not correlate with translocation of nPKC delta or nPKC epsilon (Clerk A. Bogoyevitch MA. Andersson MB. Sugden PH, 1994. J Biol Chem 269: 32848-32857: Clerk A, Gillespie-Brown J, Fuller SJ, Sugden PH, 1996. Biochem J 317: 109-118). However, ET-1 and BK stimulated a similar rapid increase in [3H]InsP, formation (< 30 s), which was much greater than that seen with PE. This early phase correlated with PKC translocation. Acute or chronic exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA) or treatment with Ro-31-8220 showed that the stimulation of PI hydrolysis by PE, but not ET-1 or BK, was inhibited by activation of PKC. Furthermore, ET-1 and BK heterologously desensitized the stimulation of PI hydrolysis by PE, ET-1 or BK homologously uncoupled their own receptors from [3H]InsP3 formation, but there was no evidence of heterologous desensitization with these two agonists. Anomalously, chronic exposure to TPA increased the stimulation of PI hydrolysis by BK, but this probably resulted from an increase in BK receptor density. PLD was also rapidly activated by TPA. ET-1, BK or PE. Experiments with Ro-31-8220 showed that the stimulation of PLD by ET-1 and BK was mediated through activation of PKC. We discuss the characteristics of the activation of PI hydrolysis and PLD by ET-1, BK, and PE with respect to the translocation of PKC.

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Ventricular myocytes are exposed to various pathologically important cell stresses in vivo. In vitro, extreme stresses (sorbitol-induced hyperosmotic shock in the presence or absence of okadaic acid, and anisomycin) were applied to ventricular myocytes cultured from neonatal rat hearts to induce a robust activation of the 46 and 54 kDa stress-activated protein kinases (SAPKs). These activities were increased in nuclear extracts of cells in the absence of any net import of SAPK protein. Phosphorylation of ATF2 and c-Jun was increased as shown by the appearance of reduced-mobility species on SDS/PAGE, which were sensitive to treatment with protein phosphatase 2A. Hyperosmotic shock and anisomycin had no effect on the abundance of ATF2. In contrast, cell stresses induced a greater than 10-fold increase in total c-Jun immunoreactivity detected on Western blots with antibody to c-Jun (KM-1). Cycloheximide did not inhibit this increase, which we conclude represents phosphorylation of c-Jun. This conclusion was supported by use of a c-Jun(phospho-Ser-73) antibody. Immunostaining of cells also showed increases in nuclear phospho-c-Jun in response to hyperosmotic stress. Severe stress (hyperosmotic shock+okadaic acid for 2 h) induced proteins (migrating at approx. 51 and 57 kDa) that cross-reacted strongly with KM-1 antibodies in both the nucleus and the cytosol. These may represent forms of c-Jun that had undergone further modification. These studies show that stresses induce phosphorylation of transcription factors in ventricular myocytes and we suggest that this response may be pathologically relevant.