Sample records for DESPOLARIZACION (depolarization)
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1

Manejo e interpretación polarimétrica de las matrices de Mueller

Espinosa-Luna, R; Hinojosa-Ruíz, S; Atondo-Rubio, G
2009-06-01

Resumen en español Se aplican la métrica de despolarización escalar Q(M) y un análisis polarimétrico gráfico a varias matrices de Mueller reportadas. Se presenta un breve repaso de los principales conceptos polarimetricos y las métricas de despolarización escalares existentes. Se demuestra que la métrica escalar Q(M) genera resultados consistentes con las métricas reportadas y que brinda una mayor información sobre la naturaleza interna de las matrices de Mueller. Resumen en inglés The Q(M) depolarization scalar metric and a graphical polarimetric analysis are applied to several reported Mueller matrices. A brief review of the main polarimetric concepts and the depolarizations scalar metrics is presented. It is shown the depolarization scalar metric Q(M) provides consistent results with the reported scalar metrics and offers more information about the internal nature of the Mueller matrix.

Scientific Electronic Library Online (Spanish)

2

Bases fisiológicas para una interacción entre las células cromafines y las endoteliales de la glándula adrenal/ Physiological bases for an interaction between chromaffin and endothelial cells from the adrenal gland

LUXORO, MARIO; VINET, RAUL
2001-03-01

Resumen en español En este trabajo tratamos de investigar las posibles interacciones entre las células endoteliales de la glándula adrenal y aquellas sustancias relacionadas con la secreción de las células cromafines. Para lo anterior, estudiamos el efecto de acetilcolina (ACh), o de catecolaminas (CA) tanto en el nivel de Ca2+ citoplasmático ([Ca2+]i), como en el potencial de membrana de las células endoteliales. Nuestros resultados muestran que tanto la ACh como la nicotina, pero no (mas) la muscarina, son capaces de inducir un aumento del [Ca2+]i y una despolarización de la membrana plasmática de las células endoteliales. El antagonista nicotínico, hexametonium, bloquea tanto el efecto de la ACh como de la nicotina lo que sugiere la presencia de receptores nicotínicos. Por otra parte, las CA (tanto adrenalina como noradrenalina o agonistas a1-adrenérgicos) también producen un aumento del [Ca2+]i en las células endoteliales aunque no despolarización evidente. En este caso, el aumento es bifásico siendo la primera fase de un pico rápido e independiente del Ca2+ extracelular en tanto que la segunda se presenta con oscilaciones y depende tanto de que los canales de Ca2+ no estén bloqueados como de la presencia de ese ión en el medio externo. Dado que se ha demostrado que el aumento del [Ca2+]i en las células endoteliales desencadena la secreción de sustancias vasodilatadoras (prostaciclina y óxido nítrico), proponemos que éste sería un mecanismo compensatorio del sistema para contrarestar el enorme efecto vasoconstrictor de las CA secretadas por las células cromafines Resumen en inglés In this work we investigated the possible interactions between the endothelial cells from the adrenal gland and the substances related with the secretion from the chromaffin cells. In order to do so, we studied the effect of acetyl-choline (ACh) or of catecholamines (CA) on the level of the membrane potential and the cytoplasmic concentration of free calcium ([Ca2+]i) in the endothelial cells. Our results show that ACh as well as nicotine, but not muscarine, are able to i (mas) nduce an increase in [Ca2+]i and membrane depolarization of the endothelial cells. The nicotinic antagonist, hexamethonium, inhibits both the action of nicotine and of ACh, which suggests the presence of nicotinic receptors. On the other hand, CA (adrenaline as much as noradrenaline or a1-adrenergic agonists) also produce a rise in [Ca2+]i in endothelial cells but not a clear depolarization. In this case, the increase is biphasic, being the first phase a very rapid peak, independent of the external Ca2+ while the second phase shows oscillations and depends on the extracellular Ca2+. This phase is diminished if the calcium channels are blocked. Since it has been demonstrated that an increment of [Ca2+]i in endothelial cells triggers the secretion of vasodilator substances such as prostacyclin and nitric oxide, we propose that this might be a compensatory mechanism in order to compensate the enormous vasoconstrictor effect that the secreted CA should have

Scientific Electronic Library Online (Spanish)

3

Manifestaciones eléctricas de alteraciones miocárdicas asociadas a preexcitación ventricular/ On the electrical manifestations of some heart diseases associated with ventricular preexcitation

de Micheli, A; Iturralde, P; Medrano, Gustavo A
2006-12-01

Resumen en español En presencia de un síndrome de WPW asociado a cardiopatía, las curvas eléctricas deben analizarse con apego a la sucesión del proceso de activación ventricular y a la posición y rotación cardíacas. Un intervalo de más de 30 mseg entre el fin del empastamiento inicial (delta) y el vértice de la onda R en las derivaciones izquierdas unipolares, que ven acercarse los frentes de la despolarización, o el eje mayor de las curvas vectocardiográficas ventriculares cor (mas) respondientes, permite inferir la coexistencia de crecimiento del ventrículo izquierdo. Por su lado, irregularidades o distorsiones aisladas de las curvas eléctricas hacen sospechar la existencia de una zona inactivable circunscrita. Deformaciones extensas o múltiples de dichas curvas hacen pensar en daño miocárdico difuso. Aveces, pueden presentarse signos de preexcitación debida a la acción de fármacos. Resumen en inglés Electro-Vectorcardiographic curves, corresponding some heart diseases, must be analyzed in the light of the ventricular depolarization sequence, as well as on the heart's position and rotation. A more than 30-msec interval between the end of the initial slurring (delta) and the vertex of the R wave in the left unipolar leads or the main axis of the vectorcardiographic ventricular curves, allows us to infer the coexistence of left ventricular hypertrophy. On the other hand (mas) , segmental irregularities or distorsions of the electric curves suggest the presence of a limited myocardial zone unable to be activated. Extensive or multiple deformations of these curves are more suggestive of a diffuse myocardial damage. Sometimes signs of preexcitation, due to a pharmacological action, can also appear.

Scientific Electronic Library Online (Spanish)

4

Acerca del valor diagnóstico de los hallazgos ECG indirectos de infarto miocárdico posterolateral basal izquierdo/ On the diagnostic value of indirect electrocardiograhic signs of left posterolateral basal infarction

de Micheli, Alfredo; Aranda, Alberto; Medrano, Gustavo A.
2007-06-01

Resumen en español El infarto posterolateral basal izquierdo no da ondas Q patológicas ni complejos ventriculares QS en las derivaciones laterales bajas V5 y V6. Por eso, el aumento de voltaje de las ondas R en las derivaciones V2 y/o transicionales (V3 y V4) constituye el único signo indirecto, sospechoso de la existencia de dicha zona inactivable, en el electrocardiograma convencional. En tales casos, se impone evidentemente el diagnóstico diferencial con una hipertrofia ventricular iz (mas) quierda o de ambos ventrículos. Por eso, conviene registrar derivaciones torácicas posteriores izquierdas o un círculo torácico completo. Presentamos tres ejemplos, dos experimentales y otro clínico, en los que los registros electrocardiográficos obtenidos correspondían a los hallazgos anatómicos de infarto posterolateral basal de la pared libre del ventrículo izquierdo. Esto aboga a favor del valor diagnóstico -no absoluto, sino relativo- de los signos electrocardiográficos indirectos de los trastornos de la despolarización y la repolarización ventriculares, originados en las regiones posterolaterales basales de la pared libre del ventrículo izquierdo. Resumen en inglés The left basal posterolateral infarct does not give pathological Q waves nor ventricular QS complexes in the low lateral leads V5 and V6. For that, the increased voltage of R waves in the lead V2 and or transitional leads V3 and V4, constitutes only an indirect sign of the presence of dead myocardium in the left posterolateral basal regions. Naturally, in these cases, a differential diagnosis with left ventricular or biventricular hypertrophy is mandatory. Therefore it is (mas) suitable to register left posterior thoracic leads V7-V9 or, preferably, a complete thoracic circle. We present here three examples: two experimental and another clinical, in which the electrocardiographic findings corresponded to anatomical data of a left posterolateral basal infarction. This fact speaks for a no absolute but relative diagnostic value of the indirect electrocardiographic signs of altered ventricular depolarization and repolarization in the left posterolateral basal regions of the left ventricle.

Scientific Electronic Library Online (Spanish)

5

Aspectos eléctricos de la asociación de miocardio inactivable y bloqueos tronculares de grado intermedio/ Electrical manifestations of dead myocardium associated to proximal blocks of intermediate degree

de Micheli, A; Aranda, A; Medrano, Gustavo A
2007-03-01

Resumen en español Se exponen las manifestaciones electrocardiográficas del miocardio inactivable, septal y parietal, asociado a bloqueos de rama de grado intermedio, es decir con un fenómeno de > parcial. Dicha exposición se realiza con base en estudios experimentales previos y se valida con cotejos electro-anatómicos en casos clínicos. En las investigaciones experimentales previas, se habían registrado asimismo los cambios eléctricos producidos al variar el grado de (mas) l bloqueo coexistente con el infarto. En el caso de un bloqueo troncular izquierdo de grado intermedio, se observan pequeñas ondas Q en derivaciones unipolares izquierdas correspondientes a la zona del miocardio afectado, en donde se acentúan los signos de lesión subepicárdica o transmural. Cuando coexiste un bloqueo troncular derecho, las modificaciones más importantes son las de las morfologías registradas en las derivaciones epicárdicas y precordiales derechas. Los cambios eléctricos se deben a la orientación espacial de las fuerzas electromotrices de la activación ventricular. Las modificaciones descritas pueden comprenderse de manera satisfactoria a la luz de los conocimientos actuales acerca de los procesos de despolarización y repolarización ventriculares. Resumen en inglés The electrical manifestation of dead myocardium associated to incomplete bundle branch block, i.e., with a limited > phenomenon, are exposed. Our description is based on previous experimental studies and validated by electro-anatomical comparisons. In previous experimental reports, the electrical manifestations of dead myocardium in the presence of varying degrees of associated block have also been described. The main electrocardiographic changes are relate (mas) d to the location and extent of damaged region and to degree of bundle branch block. If a left bundle branch block coexists with dead myocardium, small Q waves are registered in left unipolar leads exploring the damaged area. In these leads, the signs of subepicardial or transmural injury are increased. When a right proximal block coexists, the main changes concern the morphologies registered in the unipolar right epicardial and precordial leads. The electrical changes are due to the spatial orientation of the electromotive forces of ventricular depolarization and repolarization. The electrocardiographic changes described here can be satisfactorily understood in the light of the present knowledge on the ventricular electrical phenomenon.

Scientific Electronic Library Online (Spanish)

6

Acerca de la denominación actual de infartos miocárdicos/ On the actual nomenclature of myocardial infarcts

Medrano, Gustavo A.; Aranda, Alberto; Meléndez, Gabriela; Micheli, Alfredo de
2010-06-01

Resumen en español Se examinan algunos criterios acerca de los infartos definidos en la literatura actual como inferiores e inferolaterales. Con este fin, se describen los aspectos anatómicos del corazón aislado e in situ. Se analizan también las relaciones de este último con otros órganos torácicos circunvecinos. Se representa, de manera esquemática, el corazón como una pirámide con base triangular y sus lados y bordes en relación con las paredes de la caja torácica. Se resume, (mas) además, la orientación espacial de los principales vectores resultantes de los procesos de despolarización y repolarización ventriculares. Se subraya la utilidad del registro de las derivaciones unipolares torácicas posteriores V7, V8, V9 y del círculo torácico electrocardiográfico. Esto permite detectar la existencia de un infarto miocárdico agudo en regiones medias y básales de la pared inferolateral del corazón y su verdadera extensión. Con base en cotejos electroanatómicos previos, se concluye que las derivaciones V7 - V9 exploran los segmentos inferior e inferolateral en su tercio basal y medio, anteriormente denominados regiones cardiacas posterolaterales. Los registros electrocardiográficos proporcionan datos esencialmente funcionales y las imágenes obtenidas por resonancia magnética dan una información sobre todo estructural. Por lo tanto, ambos procedimientos de exploración cardiaca no deben contraponerse, sino integrarse. Resumen en inglés Certain criteria are examined for infarctions currents defined as inferior or inferolateral. To do this, certain considerations on the anatomical aspects of isolated and in situ heart are laid out. The topographical relationship of the in situ heart with other adjacent thoracic organs is described. The heart is schematically represented as a pyramid with a triangular base and its walls and borders are related to walls of the thorax. The spatial orientation of the main res (mas) ulting vectors from ventricular depolarization and repolarization are summarized also. Usefulness of registering the unipolar thoracic leads V7, V8, V9 or a complete electrocardiographic thoracic circle, is underlined. This method allows to detect for of the existence of an acute myocardial infarction in the inferior and inferolateral segments in as third basal and mid cardiac regions previously denominated posterolateral. On the base of previous electro-anatomical comparisons, it is concluded that the thoracic posterior leads V7 - V9, as well as the magnetic resonance images, explore the same heart regions. Therefore, these two methods: electrocardiography which is an essentially functional method and magnetic resonance that especially focus on structural changes are not contradictory but rather complementary tests.

Scientific Electronic Library Online (Spanish)

7

EFECTO DEL ION CITRATO EN EL COMPORTAMIENTO ELECTROQUÍMICO DEL ESTAÑO Y EL ACERO/ EFFECT OF THE CITRATE ION ON THE ELECTROCHEMICAL BEHAVIOR OF TIN AND STEEL/ EFEITO DO ÍON CITRATO NO COMPORTAMENTO ELETROQUÍMICO DO ESTANHO E DO AÇO

Calderón, Jorge A.; Paula M., Montoya
2007-12-01

Resumen en portugués O presente trabalho tem como objetivo contribuir com o conhecimento do comportamento eletroquímico da folha de flandes em meios contendo íons citrato, bem como o papel que a concentração de íon citrato desempenha na estabilidade dos recipientes. Os estudos eletroquímicos foram conduzidos a partir dos materiais individuais que constituem o ferro estanhado, ou seja, o aço e o estanho. Os experimentos foram realizados utilizando- se técnicas de polarização potencio (mas) dinâmica e de impedância eletroquímica em eletrodos formados, separadamente, por aço e estanho que permaneceram imersos em soluções de citrato, a pH 3,0 com diferentes concentrações. Foi evidenciado que o íon citrato apresenta um efeito notável de depolarização anódica no estanho pela formação de complexos estáveis e solúveis. Consequentemente, o estanho se torna anódico em relação ao aço e oferece uma proteção anticorrosiva aos substratos de aço que constituem os recipientes de ferro estanhado. Resumen en español El presente trabajo pretende hacer un aporte al conocimiento del comportamiento electroquímico de recipientes de hojalata en medio del ion citrato, y al papel que juega la concentración de dicho ion en la estabilidad de los recipientes. Todo ello, a través del estudio electroquímico individual de los materiales con los cuales son fabricados los recipientes de hojalata, acero y estaño. El estudio se llevó acabo mediante medidas de polarización potenciodinámica e im (mas) pedancia electroquímica sobre electrodos fabricados con ambos materiales e inmersos en soluciones de diferentes concentraciones de citrato a un valor de pH de 3,0. Se evidencia que a este valor de pH, el ion citrato ejerce un notable efecto de despolarización anódica sobre el estaño, por la formación de complejos solubles y estables. Esto hace que el estaño se torne anódico respecto al acero pudiendo otorgar una protección anticorrosiva al sustrato de acero de los recipientes de hojalata. Resumen en inglés The present work tries to do a contribution to the knowledge of the electrochemical behavior of tinplate containers in citrate ion medium and the role that citrate ion concentration plays on the stability of the containers; all that, through the individual electrochemical study of the materials of which the tinplate is made, steel and tin. The study was done by potentiodynamic polarization and electrochemical impedance on electrodes made with both materials, immersed in s (mas) olutions of different citrate concentrations at pH 3,0. It was evidenced that the citrate ion has a remarkable effect of anodic depolarization on tin with the formation of soluble and stable complexes. This causes that tin becomes anodic with respect to the steel being able to grant an anticorrosive protection to the steel substrate of the tinplate containers.

Scientific Electronic Library Online (Spanish)

8

Alteraciones hidroelectrolíticas y ácido-base más frecuentes en el paciente con diarrea/ Diarrhea and vomiting cause dehydration and electrolyte imbalance

Pizarro-Torres, Daniel
2005-02-01

Resumen en español Como consecuencia de la pérdida de agua y electrolitos por heces y por vómitos en la enfermedad diarreica aguda se produce deshidratación. Las alteraciones iónicas principales son: hipernatremia (cuando se ofrecen líquidos hiperosmolares o con alta concentración de sodio) y la hiponatremia (si se ofrecen líquidos hipoosmolares y faltos o pobres en sodio). La deshidratación normonatrémica es la más frecuente. La deshidratación produce una reacción de vasoconstr (mas) icción. La contracción de espacio vascular priva de oxígeno a muchos tejidos, cuyas células recurren a la mayor producción de ATP por la vía de la glucólisis y su utilización da por resultado gran producción de hidrogeniones y lactato, los que no pueden ser convertidos a ATP por la mitocondria por falta de oxígeno. La hipoxia aumenta la producción de radicales o especies activadas de oxígeno (EAO) en las arteriolas periféricas. La acidemia y el aumento de las EAO abren los canales de potasio K ATP en los vasos periféricos y la salida de este ion produce hiperpotasemia y vasodilatación. Si el paciente tuvo déficit previo de este elemento puede presentar normo o hipopotasemia. Lo opuesto sucede en las arteriolas pulmonares. La acidemia y la disminución de EAO en las arteriolas pulmonares cierran los Kv y se produce despolarización de la membrana celular de los miocitos y vasoconstricción pulmonar. También la acidemia abre los canales de cloro ClC-2 con lo que se produce una salida de este ion hacia el espacio extracelular. Las alteraciones de calcio, fosfato y magnesio son mínimas. La administración de soluciones polielectrolíticas balanceadas, sea por vía oral, o endovenosa cuando fuera necesario, logran corregir en poco tiempo todas estas alteraciones revertiendo la hipertensión pulmonar y normalizando la presión arterial periférica. Resumen en inglés Normonatremic dehydration is by far the most common electrolyte imbalance. Hyponatremic and hypernatremic dehydration are less frequent and are caused by offering the patient hypotonic fluid in cases presenting hyponatremic dehydration or hypertonic and/or fluid containing high sodium concentration in cases presenting hypernatremic dehydration. Dehydration promotes vasoconstriction. Intravascular space contraction causes tissue hypoxia. The aerobic ATP production in mitoc (mas) hondria diminishes, the glycolytic ATP production is enhanced and its consumption yields high hydrogen and lactate concentration, causing acidemia. The production of activated oxygen species (AOS) increases in systemic arteries and diminishes in pulmonary arterioles. Acidemia and AOS open K ATP in systemic arteries. Potassium extrusion causes hyperpotassemia, hyperpolarization of miocytes and vasodilatation. In pulmonary arterioles acidemia and diminishing in AOS release cause closure of Kv, membrane depolarization and pulmonary vasoconstriction. Acidemia causes opening of Cl-C2 chloride channels and outward rectification. Imbalance in calcium, phosphate and magnesium is minimum. Oral or intravenous rehydration with balanced polyelectrolytic rehydration solution rehydrates successfully the diarrheic dehydrated patients presenting electrolyte and acid-base imbalance.

Scientific Electronic Library Online (Spanish)

9

Two populations of kainate receptors with separate signaling mechanisms in hippocampal interneurons

Rodríguez-Moreno, Antonio; López-García, Juan C.; Lerma Gómez, Juan
2000-02-01

Digital.CSIC (Spain)

10

Thromboxane A2-Induced Inhibition of Voltage-Gated K+ Channels and Pulmonary Vasoconstriction

Cogolludo, Angel; Moreno, Laura; Boscá, Lisardo; Tamargo, Juan; Perez-Vizcaino, Francisco
2003-10-03

Digital.CSIC (Spain)

11

The transcription factor early growth response factor-1 (EGR-1) promotes apoptosis of neuroblastoma cells

Pignatelli, Miguel; Luna Medina, Rosario de; Pérez-rendón, Arturo; Santos, Ángel; Pérez Castillo, Ana
2003-08-01

Digital.CSIC (Spain)

12

The location and properties of the Taxol binding center in microtubules: a picosecond laser study with fluorescent taxoids

Lillo, M. Pilar; Cañadas, Olga; Dale, Robert. E.; Acuña Fernandez, Alberto Ulises
2000-01-01

Digital.CSIC (Spain)

14

The Conformation of Serum Albumin in Solution: A Combined Phosphorescence Depolarization-Hydrodynamic Modeling Study

Ferrer, M. Luisa; Duchowicz, Ricardo; Carrasco, Beatriz; García de la Torre, José; Acuña Fernandez, Alberto Ulises

There is a striking disparity between the heart-shaped structure of human serum albumin (HSA) observed in single crystals and the elongated ellipsoid model used for decades to interpret the protein solution hydrodynamics at neutral pH. These two contrasting views could be reconciled if the protein w...

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15

The Conformation of Serum Albumin in Solution: A Combined Phosphorescence Depolarization-Hydrodynamic Modeling Study

Ferrer, M. Luisa; Duchowicz, Ricardo; Carrasco, Beatriz; García de la Torre, José; Acuña Fernandez, Alberto Ulises
2001-05-01

Digital.CSIC (Spain)

16

Sugammadex: presente y futuro/ Sugammadex: present and future

Gómez Hernández, Ariel; Bello Frías, Roberto; Lister Pérez, Annet
2010-08-01

Resumen en español Introducción: Uno de los principales problemas en anestesiología es que el despertar del paciente y la recuperación de su actividad neuromuscular no se producen al unísono. La nueva ciclodextrina llamada Sugammadex, supone un nuevo enfoque farmacológico, revolucionario y totalmente distinto al procedimiento actual en la reversión del efecto de los bloqueadores neuromusculares no despolarizantes. Objetivos: Realizar una puesta al día en cuanto a lo que este fármaco (mas) representa para la farmacología neuromuscular y su aplicación. Desarrollo: Se consultó una amplia y actualizada literatura sobre este novedoso agente reversor de la relajación muscular. Conclusiones: Sin tentaciones apresuradas, todo indica que se abre un camino espectacular que puede cambiar la forma de utilizar los relajantes musculares en un futuro próximo. Resumen en inglés Introduction: One of the major problems in anesthesiology is that the patient's wake and recovery of her neuromuscular activity are not produced at the same time. The new Cyclodextrin called Sugammadex, entails a new pharmacologic approach , revolutionary and completely different to present procedure in reversion of the non-depolarization neuromuscular blockers effect. Objectives: To update on the representation of this drug for the neuromuscular pharmacology and its appl (mas) ication. Development: Authors made an extensive and updated review of the literature on this novel reversion agent of muscular relaxation. Conclusions: Without hurried temptations, all indicates that a new route is appearing that may to change the way of utilization of the muscular relaxing agents in a near future.

Scientific Electronic Library Online (Spanish)

17

Stress-induced depolarization of (Pb, La)TiO3 ferroelectric thin films by nanoindentation

Algueró Giménez, Miguel; Bushby, A. J.; Reece, M. J.; Poyato, Rosalia; Ricote Santamaría, Jesús; Calzada Coco, María Lourdes; Pardo Mata, Lorena
2001-12-03

Digital.CSIC (Spain)

18

Relaxation behavior, at very low frequencies, of glassy polymers containing aliphatic-aromatic side groups in their structures

Saez Torres, P.; Sanchis, M. J.; Díaz Calleja, Ricardo; Guzmán Perote, Julio; Riande, Evaristo
2000-08-01

Digital.CSIC (Spain)

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20

Receptores Sur y Sulfonilureas en el tratamiento de la Diabetes Mellitus Tipo 2

Contreras, F; Romero, B; Suárez, N; González, M; Fouillioux, C; Guevara, E; Betancourt, MC; Torres, D; Velasco, M
2002-07-01

Resumen en español Las Sulfonilureas son hipoglicemiantes orales usados en el tratamiento de la Diabetes Mellitus tipo 2, que actúan estimulando la secreción de insulina por parte de las células b del páncreas. Estudios recientes revelaron que estos fármacos se unen a receptores específicos en la membrana celular de los islotes pancreáticos induciéndose el cierre de los canales de potasio sensibles a ATP, lo que provoca aumento en el contenido intracelular de potasio y despolarizaci (mas) ón de la célula conduciendo a la apertura de los canales de calcio voltaje dependiente entrando este al intracelular y liberándose insulina a partir de los gránulos maduros. Los canales de potasio sensibles a ATP están formados por la subunidad KIR6, 2 la cual forma el poro del canal y la subunidad receptora de sulfonilureas (SUR) que actúa como reguladora. Tres subtipos de receptores SUR han sido reconocidos hasta ahora: el tipo pancreático SUR1, cuya inhibición facilita la secreción de insulina; el tipo cardiaco SUR2A el cual suministra protección miocárdica y un tercer tipo en el músculo liso vascular SUR2B el cual juega un rol en la tonicidad vascular. Resumen en inglés The sulfonylureas are well-known insulin secretagogues widely used as oral hypoglycemic agents in the treatment of type 2 diabetes mellitus. Recent studies have revealed that their principle target is the sulfonylurea receptor, a component of the ATP-sensitive potassium channel (K-ATP). Closure of the K+-ATP channel causes membrane depolarization which, in turn, triggers calcium influx through voltage-gated Ca2+ channels, and thereby stimulates the exocytosis of insulin-c (mas) ontaining secretory granules. K+ - ATP channels are formed from KIR6, 2 and sulfonylurea receptor (SUR) subunits. KIR6, 2 forms the channel pore, while the sulfonylurea receptor acts as a regulatory subunit. Three subtypes of SURs have been recognized to date: pancreatic type (SUR1), the inhibition of which facilitates insulin secretion; cardiac type (SUR2A), which provides myocardial protection; and vascular smooth muscle type (SUR2B), which plays a role in vasorelaxation.

Scientific Electronic Library Online (Spanish)

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22

Nature of the magnetic ordering for small mean-size and large-size mismatch of A-site cations in CMR manganites.

Yusuf, S. M.; Teresa, José María de; Algarabel, Pedro A.; Blasco, Javier; Ibarra, M. Ricardo; Kumar, Amit; Ritter, C.
2006-11-15

Digital.CSIC (Spain)

23

Natural Triterpenic Diols Promote Apoptosis in Astrocytoma Cells through ROS-Mediated Mitochondrial Depolarization and JNK Activation

Martín, Rubén; Ibeas, Elvira; Carvalho-Tavares, Juliana; Hernández, Marita; Ruiz-Gutierrez, Valentina

14 pages, 8 figures and Figures S1 found at: doi:10.1371/journal.pone.0005975.s001 (0.93 MB TIF) | [Background]Triterpene alcohols and acids are multifunctional compounds widely distributed throughout the plant kingdom that exhibit a variety of beneficial health properties, being synthetic analogs...

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24

Natural Triterpenic Diols Promote Apoptosis in Astrocytoma Cells through ROS-Mediated Mitochondrial Depolarization and JNK Activation

Martín, Rubén; Ibeas, Elvira; Carvalho-Tavares, Juliana; Hernández, Marita; Ruiz-Gutierrez, Valentina; Nieto, María Luisa
2009-06-22

Digital.CSIC (Spain)

25

Mueller-Stokes characterization and optimization of a liquid crystal on silicon display showing depolarization

Márquez Ruiz, Andrés; Moreno Soriano, Ignacio; Iemmi, Claudio; Lizana Tutusaus, Ángel; Campos Coloma, Juan; Yzuel Giménez, María Josefa

In this paper we characterize the polarimetric properties of a liquid crystal on silicon display (LCoS), including depolarization and diattenuation which are usually not considered when applying the LCoS in diffractive or adaptive optics. On one hand, we have found that the LCoS generates a certain ...

DRIVER (Spanish)

26

Modulation of mitochondrial Ca2+ uptake by estrogen receptor agonists and antagonists

Lobatón, C. D.; Vay, Laura; Hernández-SanMiguel, Esther; Santo-Domingo, Jaime; Moreno, Alfredo; Montero Zoccola, Mayte; Álvarez, Javier
2005-08-01

Digital.CSIC (Spain)

28

Interaction of Mg2+ and phencyclidine in use-dependent block of NMDA channels

Lerma Gómez, Juan; Zukin, R. Suzanne; Bennet, Michael V.
1991-02-25

Digital.CSIC (Spain)

29

Estimulación magnética transcraneal para síntomas negativos en la esquizofrenia: una revisión/ The transcraneal magnetic stimulation for the negative symptoms in schizofrenia: a review

Zelaya Vásquez, Rina María; Saracco-Álvarez, Ricardo A.; González Olvera, Jorge
2010-04-01

Resumen en español La estimulación magnética transcraneal (EMT) es un método no invasivo que utiliza campos magnéticos alternantes para inducir corrientes eléctricas en el tejido cortical en diferentes áreas cerebrales. Se considera una forma de tratamiento para diferentes trastornos psiquiátricos, especialmente en la depresión, adicciones y esquizofrenia. Está técnica terapéutica ofrece una vía innovadora para estudiar la excitabilidad de la corteza, la conectividad regional co (mas) rtical, la plasticidad de las respuestas cerebrales y las funciones cognitivas en el estado del enfermo. Aunque se han documentado resultados positivos en la estimulación de la CPF izquierda y en la CPF derecha, se sugiere que puede ejercer su acción beneficiosa a través de diversos mecanismos de acción aún no comprendidos en su totalidad. La corteza prefrontal humana es esencial en el control e integración de las emociones, la cognición y la regulación del Sistema Nervioso Autónomo. Numerosas conexiones neuronales bidireccionales se originan en la CPF y se extienden al resto de las áreas de asociación cortical, región insular, sistema límbico y los ganglios basales. La CPF modula la actividad dopaminérgica mesencefálica mediante una vía activadora y otra inhibidora, lo que permite una regulación sumamente fina de la actividad dopaminérgica. La vía activadora funciona por medio de proyecciones glutamatérgicas directas e indirectas a las células dopaminérgicas. La vía inhibitoria hace lo propio mediante eferencias glutamatérgicas prefrontales a las interneuronas GABAérgicas mesencefálicas y a las neuronas GABAérgicas estriatomesencefálicas. El modelo de la doble modulación del sistema dopaminérgico mesolímbico demuestra que la concentración dopaminérgica extracelular en el núcleo accumbens disminuye o aumenta después de la estimulación de la corteza prefrontal a baja o alta frecuencia, respectivamente. Dentro de los estudios que utilizan la EMT en la esquizofrenia, se ha encontrado que, tras una EMT de alta frecuencia (>1Hz) o repetititiva (EMTr), hay un aumento de la excitabilidad en varias áreas cerebrales, mientras que la excitabilidad cortical disminuye tras una EMT de baja frecuencia ( Resumen en inglés Schizophrenia is one of the most studied diseases in psychiatry and different dysfunctions of thinking, emotions, perception, movement, and behavior converge in it. These dysfunctions affect the quality of life of the patients in different ways. It is a disease that has been observed in the whole world, with a 0.5 to 1.5% prevalence among adults. Although the biological basis of schizophrenia is not clear enough, the dopaminergic hypothesis is preponderant in our understa (mas) nding of the symptoms of the disease. A mesolimbic pathway hyperactivity is related to a positive symptomathology, while a prefrontal dopaminergic hypofunction relates to negative symptoms. It has been observed that using serotoninergic antagonists, which promote dopaminergic activity in the prefrontal cortex, translates in to a reduction of the intensity of negative symptoms. This negative syndrome includes a difficulty to initiate new activities (apathy), speech and creativity impoverishment (alogia), alterations in emotional expression, and a lack of capacity to experiment joy. Patients with negative symptoms present gray and white matter loss in left-sided cerebral structures, including temporal lobe, anterior cingulated, and medial frontal cortex. Such a loss seems to be more evident in prefrontal regions, such as the dorsolateral prefrontal region, which connects with anterior temporal structures. Persistent negative symptomathology is a concept proposed by Buchanan, which must fulfill the following criteria: symptoms are primary to the disease or secondary but have not responded to current treatment; interfere with the patient's capacity to accomplish normal functioning; persist during periods of clinical stability, and represent an unresolved therapeutic need. They must be measurable by clinical scales and persist, at least, six months. The Food and Drug Administration has recently considered negative symptoms as an investigation target or new treatments due to their prevalence and high negative impact in the life of the schizophrenic population. Nowadays, the current treatments available for such an entity are second generation antipshycotics and glutamatergic agents -such as d-cycloserine and glicine-, amisulpiride and seleginine, even though their efficacy is limited. Dysfunction of the human prefrontal cortex is considered to be implicated in the pathophisiology of negative symptoms. This cerebral region is essential in the regulation of emotions and cognition. Multiple neural networks begin in the prefrontal cortex and go towards other cortical association areas, to insular region, thalamic structures, basal ganglia and limbic system. It regulates dopaminergic mesencephalic activity through activating and inhibitory pathways, allowing a precise regulation of dopaminergic activity. This double modulation model of dopaminergic pathways has been recently sustained by studies which prove that extracellular dopaminergic concentration in nucleus accumbens increases or reduces after a high or low frequency stimulation of the prefrontal cortex, respectively. A prefrontal cortex lesion causes a syndrome similar to the negative symptomathology in schizophrenia. Transcraneal magnetic stimulation (TMS) could be effective in the treatment of negative symptoms by activating the prefrontal cortex, maybe by stimulating the liberation of dopamine in the mesolimbic and mesoestriatal pathways which have a crucial role in the pathogenesis of negative symptoms such as apathy and anhedonia. TMS was introduced in 1985 and since the early 90's its potential as a treatment has been tested in numerous neurological and psychiatric conditions. It is a noninvasive means of stimulating nervous cells in superficial areas of the brain. During a TMS procedure, an electrical current passes through a wire coil placed over the scalp. This induces a magnetic field that can produce a substantive electrical field in the brain. This electrical field produces in turn a depolarization of nervous cells resulting in the stimulation or disruption of brain activity. TMS may be applied as a single stimulus or repeated many times per second (repetitive TMS), with variations in the intensity, site, and orientation of the magnetic field. Most research and interest has focused on the potential application of repetitive TMS (rTMS) in the treatment of depression. In addition, in recent years an increasing number of open and double-blinded studies of rTMS were conducted in patients with schizophrenia. Most investigators have chosen to focus on the treatment of specific refractory symptoms or syndromes within the disorder such as refractory auditory hallucinations or persistent negative symptoms. TMS has become widely used in research, especially as a method to probe normal and abnormal brain function, motor cortical physiology, and cognition. Regarding negative symptoms in schizophrenia, eleven studies using TMS were carried out until 2006, with a total of 172 patients studied. These studies are difficult to compare because they used different stimulation parameters and the symptoms described were heterogenic. Six studies were blind and five were open, using high frequency TMS in all of them (frequencies above 1 Hz), which is the type of stimulation most commonly used in treatment studies. Six of these studies found a reduction in the severity of the symptoms, but the reduction was not significant in two of them. Ten were the maximum number of sessions included in every study, except for one, in which 20 sessions of TMS were given. In this study, the score of negative subscale of the PANSS was reduced in 33%, which is considered a significant response, and this result was sustained within the next month. In one of these studies, researchers compared 3- and 20-Hz stimulation with sham stimulation and stimulation provided at the patient's individual alpha frequency. Alpha-frequency stimulation was calculated as the patient's peak alpha frequency from five frontal EEG leads. Stimulation of alpha frequency resulted in a significantly greater reduction in negative symptoms than the other conditions. This finding could suggest that negative symptoms may specifically relate to alpha EEG oscillations, which is interesting and requires further exploration and confirmation. Another two studies were conducted in 2007; in the first one, no improvement in negative, positive of affective symptoms was found. The second one, which was a double-blinded clinical trial, found a significant reduction in the intensity of negative, positive, and general symptoms with the active TMS. We should remark that TMS produces changes in the cortical activity in ventral and dorsoestratial regions, but other cerebral regions could be stimulated too, since some activation abnormalities in the left globus palidus, bilateral caudate nucleus, prefrontal, and temporal right cortex have been found and are associated with the etiology of the negative syndrome. In addition, it will be interesting to see whether changes in subcortical dopamine release, which were shown with rTMS in normal volunteers, can be demonstrated in clinical populations, such as patients with schizophrenia, and how this may relate to response to treatment. There is still a need for a larger number of controlled studies, with larger samples, longer periods of evaluation, and constant stimulation parameters, so they can be compared between them and the exact efficacy of TMS as a treatment for negative symptoms can be established.

Scientific Electronic Library Online (Spanish)

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Electrophysiological and behavioral responses of a Cuban population of the sweet potato weevil to its sex pheromone

Sureda, Tania; Quero, Carmen; Bosch, María Pilar; Avilés, Rubén; Coll, Francisco; Renou, Michel; Guerrero, Ángel
2006-09-15

Digital.CSIC (Spain)

31

Detailed neutron study of the crossover from long-range to short-range magnetic ordering in (Nd1−xTbx)0.55Sr0.45MnO3 manganites

Teresa, José María de; Ritter, C.; Algarabel, Pedro A.; Yusuf, S. M.; Blasco, Javier; Kumar, Amit; Marquina, Clara; Ibarra, M. Ricardo
2006-12-01

Digital.CSIC (Spain)

32

Defective TNF-α–mediated hepatocellular apoptosis and liver damage in acidic sphingomyelinase knockout mice

García Ruiz, Carmen; Colell, Anna; Marí, Montserrat; Morales, Albert; Calvo, María; Enrich, Carlos; Fernández Checa, José C.
2003-01-15

Digital.CSIC (Spain)

33

Combined Mueller and Jones matrix method for the evaluation of the complex modulation in a liquid-crystal-on-silicon display

Moreno Soriano, Ignacio; Lizana Tutusaus, Ángel; Campos Coloma, Juan; Márquez Ruiz, Andrés; Iemmi, Claudio; Yzuel Giménez, María Josefa

We apply the polar decomposition of the Mueller matrix describing a liquid-crystal-on-silicon display to identify the diattenuator, depolarizer, and retarder contributions as a function of the gray level. The retarder contribution is expressed in terms of the equivalent Jones matrix to apply previou...

DRIVER (Spanish)

34

Cell proliferation depends on mitochondrial Ca2+ uptake: inhibition by salicylate

Núñez Llorente, Lucía; Senovilla, Laura; Sanz-Blasco, Sara Isabel; García-Sancho, Javier; Villalobos Jorge, Carlos; Valero, Ruth A .
2006-02-15

Digital.CSIC (Spain)

35

Calcineurin-independent inhibition of mitochondrial Ca2+ uptake by cyclosporin A

Montero Zoccola, Mayte; Lobatón, C. D.; Gutiérrez-Fernández, S.; Moreno, Alfredo; Álvarez, Javier
2004-01-01

Digital.CSIC (Spain)

36

Aspectos electrocardiográfícos de la hipertrofia ventricular derecha en el cor pulmonale crónico/ Electrocardiographs features of right ventricular hypertrophy in chronic cor pulmonale

de Micheli, Alfredo; Aranda, Alberto; Medrano, Gustavo A
2006-03-01

Resumen en español Se exponen los criterios electrofisiológicos para el diagnóstico electrocardiográfico de los crecimientos ventriculares derechos, a la luz de la sucesión del proceso de activación del miocardio ventricular. La hipertrofia ventricular derecha por sobrecarga sistólica sostenida puede ser global o segmentaria. En el primer caso, p. ej. cardiopatía hipertensiva pulmonar crónica de origen vascular, aumentan la magnitud y la manifestación de todos los principales vecto (mas) res resultantes de la activación de dicho ventrículo: IIs, IId y IIId. Si la hipertrofia ventricular derecha es de tipo segmentario, p. ej. neumopatía crónica por obstrucción bronquial, aumentan la magnitud y la manifestación sólo de algunos de los vectores resultantes de la activación del ventrículo derecho. En el caso mencionado, aumenta la manifestación del vector basal derecho: IIId. Cuando coexiste isquemia subepicárdica o transmural del ventrículo derecho, la onda T negativa en las derivaciones precordiales derechas y transicionales tiene características de tipo primario y se asocia a prolongación del intervalo Q-Tc en ausencia de acción digitálica. Se presentan dos ejemplos demostrativos de las correlaciones existentes entre datos electrocardiográficos y datos anatómicos en la hipertrofia global y en la segmentaria del ventrículo derecho, respectivamente. Resumen en inglés The electrophysiological criteria for diagnosing right ventricular hypertrophy, characteristic of chronic cor pulmonale, are described. Right ventricular hypertrophy due to a sustained systolic overload can be global or regional. In the first situation, as for example, an idiopathic pulmonary hypertension, the magnitude and manifestation of all the main vectors resulting from the depolarization of this ventricle are increased: IIs (septal), IIr (parietal), and IIIr (basal (mas) ). When the right ventricular hypertrophy is of the segmental (regional) type, as for example, that due to a chronic bronchial obstruction, the magnitude and manifestation of only some right vectors are increased. In this condition, only the magnitude of the right basal vector (IIIr) is augmented. In the presence of subepicardial or transmural ischemia of the right ventricle, negative T waves of primary type are recorded in right precordial and transitional leads, where the Q-Tc interval is prolonged in the absence of digitalis effect. Two demonstrative examples of the correlations existing between the electrocardiographic and anatomical findings in global and regional hypertrophies, respectively, of the right ventricle are presented.

Scientific Electronic Library Online (Spanish)