Browsing by Author "Echevarria, Ghislaine"

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    Dexmedetomidine preconditioning activates pro-survival kinases and attenuates regional ischemia/reperfusion injury in rat heart
    (ELSEVIER, 2012) Ibacache, Mauricio; Sanchez, Gina; Pedrozo, Zully; Galvez, Felipe; Humeres, Claudio; Echevarria, Ghislaine; Duaso, Juan; Hassi, Mario; Garcia, Lorena; Diaz Araya, Guillermo; Lavandero, Sergio
    Pharmacological preconditioning limits myocardial infarct size after ischemia/reperfusion. Dexmedetomidine is an alpha(2)-adrenergic receptor agonist used in anesthesia that may have cardioprotective properties against ischemia/reperfusion injury. We investigate whether dexmedetomidine administration activates cardiac survival kinases and induces cardioprotection against regional ischemia/reperfusion injury. In in vivo and ex vivo models, rat hearts were subjected to 30 min of regional ischemia followed by 120 min of reperfusion with dexmedetomidine before ischemia. The alpha(2)-adrenergic receptor antagonist yohimbine was also given before ischemia, alone or with dexmedetomidine. Erk1/2, Akt and eNOS phosphorylations were determined before ischemia/reperfusion. Cardioprotection after regional ischemia/reperfusion was assessed from infarct size measurement and ventricular function recovery. Localization of alpha(2)-adrenergic receptors in cardiac tissue was also assessed. Dexmedetomidine preconditioning increased levels of phosphorylated Erk1/2, Akt and eNOS forms before ischemia/reperfusion; being significantly reversed by yohimbine in both models. Dexmedetomidine preconditioning (in vivo model) and pen-insult protection (ex vivo model) significantly reduced myocardial infarction size, improved functional recovery and yohimbine abolished dexmedetomidine-induced cardioprotection in both models. The phosphatidylinositol 3-kinase inhibitor LY-294002 reversed myocardial infarction size reduction induced by dexmedetomidine preconditioning. The three isotypes of alpha(2)-adrenergic receptors were detected in the whole cardiac tissue whereas only the subtypes 2A and 2C were observed in isolated rat adult cardiomyocytes. These results show that dexmedetomidine preconditioning and dexmedetomidine pen-insult administration produce cardioprotection against regional ischemia/reperfusion injury, which is mediated by the activation of pro-survival kinases after cardiac alpha(2)-adrenergic receptor stimulation. (C) 2011 Elsevier B.V. All rights reserved.
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    Obesity Does Not Influence the Onset and Offset of Sevoflurane Effect as Measured by the Hysteresis Between Sevoflurane Concentration and Bispectral Index
    (LIPPINCOTT WILLIAMS & WILKINS, 2011) Cortinez, Luis I.; Gambus, Pedro; Troconiz, Inaki F.; Echevarria, Ghislaine; Munoz, Hernan R.
    BACKGROUND: The onset and offset of action of anesthetic gases might be delayed by respiratory changes and gas exchange alterations present in obese patients. In this study, we assessed the influence of obesity on the hysteresis between sevoflurane and its effect as measured by the bispectral index (BIS). Because the use of positive end-expiratory pressure (PEEP) in obese patients has improved gas exchange, we also assessed the influence of PEEP on hysteresis.
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    The effect of birthweight on childhood cognitive development in a middle-income country
    (2011) Torche, Florencia; Echevarria, Ghislaine
    Methods We merge birth registry information on birthweight with standardized Math and Spanish test scores for all fourth graders in Chile to create a prospective data set. Twin fixed-effects models are used to estimate the causal effect of intra-uterine growth on test scores. Fixed-effect estimates are compared with traditional regression results in a cross-section of births to gauge the omitted variable bias emerging from unobserved genetic, maternal and pregnancy-related factors in cross-sectional models.