Browsing by Author "Rey, Sergio"

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    Expression and immunolocalization of endothelin peptides and its receptors, ETA and ETB, in the carotid body exposed to chronic intermittent hypoxia
    (2007) Rey, Sergio; Corthorn, Jenny; Chacon, Cecilia; Iturriaga, Rodrigo
    Increased levels of endothelin-1 (ET-1) in the carotid body (CB) contribute to the enhancement of chemosensory responses to acute hypoxia in cats exposed to chronic intermittent hypoxia (CIH). However, it is not known if the ET receptor types A (ETA-R) and B (ETB-R) are upregulated. Thus, we studied the expression and localization of ETA-R and ETB-R using Western blot and immunohistochemistry (IHC) in CBs from cats exposed to cyclic hypoxic episodes, repeated during 8 hr for 4 days. In addition, we determined if ET-1 is expressed in the chemoreceptor cells using double immunofluorescence for ET-1 ancityrosine hydroxylase (TH). We found that ET-1 expression was ubiquitous in the blood vessels and CB parenchyma, although double ET-1 and TH-positive chemoreceptor cells were mostly found in the parenchyma. ETA-R was expressed in most chemoreceptor cells and blood vessels of the CB vascular pole. ETB-R was expressed in chemoreceptor cells, parenchymal capillaries, and blood vessels of the vascular pole. CIH upregulated ETB-R expression by similar to 2.1 (Western blot) and 1.6-fold (IHC) but did not change ETA-R expression. Present results suggest that ET-1, ETA-R, and ETB-R are involved in the enhanced CB chemosensory responses to acute hypoxia induced by CIH.
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    Expression of kallikrein, bradykinin B2 receptor, and endothelial nitric oxide synthase in placenta in normal gestation, preeclampsia, and placenta accreta
    (2006) Corthorn, Jenny; Germain, Alfredo A.; Chacon, Cecilia; Rey, Sergio; Soto, Gloria X.; Figueroa, Carlos D.; Mueller-Esterl, Werner; Duarte, Ignacio; Valdes, Gloria
    In an effort to define the varied expression of three vasoactive markers in the clinical models of normal placenta/normal invasion (n = 11), preeclampsia/restricted trophoblast invasion (n = 15), and placenta accreta/exaggerated invasion (n = 6), we performed semiquantitative immunohistochemistry for kallikrein, bradykinin 132 receptor, and endothelial nitric oxide synthase (eNOS). In the floating villi, the syncytiotrophoblast expressed more kallikrein in placenta accreta (p < 0.05), than in normal and preeclamptic placentas, while the bradykinin B2 receptor and eNOS were similarly expressed in all groups; in the fetal endothelium, the bradykinin B2 receptor was enhanced in placenta accreta (p < 0.005), but kallikrein and eNOS were similarly expressed in the other two groups. in the extravillous trophoblast, both kallikrein and eNOS expression were higher in placenta accreta (p < 0.001), while the bradykinin B2 receptor signal was only enhanced in preeclampsia (p < 0.05). The presence and localization of kallikrein, the bradykinin B2 receptor, and eNOS in the fetomaternal interface in the three study conditions supports a local role for interrelated vasodilatory/antiaggregating systems. This first report of the variations observed in kallikrein and eNOS in a condition of exaggerated trophoblast invasion supports the participation of vasodilatation in trophoblast migration.
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    Lipopolysaccharide-induced carotid body inflammation in cats: functional manifestations, histopathology and involvement of tumour necrosis factor-alpha
    (WILEY-BLACKWELL, 2008) Fernandez, Ricardo; Gonzalez, Sergio; Rey, Sergio; Cortes, Paula P.; Maisey, Kevin R.; Reyes, Edison Pablo; Larrain, Carolina; Zapata, Patricio
    In the absence of information on functional manifestations of carotid body (CB) inflammation, we studied an experimental model in which lipopolysaccharide (LPS) administration to pentobarbitone-anaesthetized cats was performed by topical application upon the CB surface or by intravenous infusion (endotoxaemia). The latter caused: (i) disorganization of CB glomoids, increased connective tissue, and rapid recruitment of polymorphonuclear cells into the vascular bed and parenchyma within 4 h; (ii) increased respiratory frequency and diminished ventilatory chemoreflex responses to brief hypoxia (breathing 100% N-2 for 10 s) and diminished ventilatory chemosensory drive (assessed by 100% O-2 tests) during normoxia and hypoxia; (iii) tachycardia, increased haematocrit and systemic hypotension in response to LPS I.V.; and (iv) increased basal frequency of carotid chemosensory discharges during normoxia, but no change in maximal chemoreceptor responses to brief hypoxic exposures. Lipopolysaccharide-induced tachypnoea was prevented by prior bilateral carotid neurotomy. Apoptosis was not observed in CBs from cats subjected to endotoxaemia. Searching for pro-inflammatory mediators, tumour necrosis factor-alpha (TNF-alpha) was localized by immunohistochemistry in glomus and endothelial cells; reverse transcriptase-polymerase chain reaction revealed that the CB expresses the mRNAs for both type-1 (TNF-R1) and type-2 TNF-alpha receptors (TNF-R2); Western blot confirmed a band of the size expected for TNF-R1; and histochemistry showed the presence of TNF-R1 in glomus cells and of TNF-R2 in endothelial cells. Experiments in vitro showed that the frequency of carotid nerve discharges recorded from CBs perfused and superfused under normoxic conditions was not significantly modified by TNF-alpha, but that the enhanced frequency of chemosensory discharges recorded along responses to hypoxic stimulation was transiently diminished in a dose-dependent manner by TNF-alpha injections. The results suggest that the CB may operate as a sensor for immune signals, that the CB exhibits histological features of acute inflammation induced by LPS, that TNF-alpha may participate in LPS-induced changes in chemosensory activity and that some pathophysiological reactions to high levels of LPS in the bloodstream may originate from changes in CB function.
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    Proinflammatory stimuli are needed for induction of microglial cell-mediated A beta PP244-C and A beta-neurotoxicity in hippocampal cultures
    (IOS PRESS, 2008) Ramirez, Gigliola; Rey, Sergio; von Bernhardi, Rommy
    Amyloid-beta plaques and neurodegeneration are hallmarks of Alzheimer's disease, where glial cells are responsible for sustained neuroinflammation. Here we show that hippocampal-microglia co-cultures exposed to proinflammatory mediators, amyloid-beta- and amyloid-beta protein precursor construct-conjugated beads increased their production of nitrites. In contrast, inflammation was unable to significantly induce cell death by itself, whereas inflammation plus amyloid-beta or amyloid-beta protein precursor induced a significant increment of cell death and a 6-fold increase of production of Interleukin 1 beta. Those effects were not observed in the absence of microglia or when hippocampal cells were co-cultured with microglia for one day. In contrast, a 2-fold increase of transforming growth factor beta 1 was observed in hippocampal cultures exposed to inflammatory stimuli for 4 days, whereas induction of transforming growth factor beta 1 by inflammation plus amyloid-beta and amyloid-beta protein precursor was nearly abolished by microglia. Our results indicate that neurotoxicity induced by amyloid-beta or amyloid-beta protein precursor was a slow process depending on activated microglia and additional stimuli. The observed cytotoxicity could be consequence of a vicious cycle in which elevated concentrations of Interleukin 1 beta and radical species along with decreased secretion of neuroprotective cytokines such as transforming growth factor beta 1 support persistent activation of glial cells and cell damage.