Browsing by Author "Quezada, C."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
- ItemAdenosine A(2B) receptor mediates an increase on VEGF-A production in rat kidney glomeruli(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2008) Valladares, D.; Quezada, C.; Montecinos, P.; Yanez, Aj.; Sobrevia, L.; Martin, R. SanUp-regulation of the glomerular expression and the activity of vascular endothelial growth factor-A (VEGF) have been identified as an early pathogenic event for the progression of diabetic nephropathy. Currently, however the mediators are not yet clearly recognized. In this study we identified all four adenosine receptor (AR) subtypes, i.e. A(1), A(2A), A(2B) and A(3) in isolated rat kidney glomeruli. We localized the expression of A(2B)AR in podocytes, the primary VEGF producing cells. The ex vivo treatment of kidney glomeruli with adenosine or a general AR agonist NECA, increases VEGF protein content. In addition, NECA treatment elicits VEGF release. These effects were blocked by the A(2B)AR selective antagonist MRS1754 supplementation. Furthermore, we showed that A(2B)AR activation was necessary to promote a higher expression of VEGF in kidney glomeruli upon exposure to high D-glucose concentration, a pathogenic condition like those observed in diabetic nephropathy. (c) 2007 Elsevier Inc. All rights reserved.
- ItemAdenosine mediates transforming growth factor-beta 1 release in kidney glomeruli of diabetic rats(WILEY, 2009) Roa, H.; Gajardo, C.; Troncoso, E.; Fuentealba, V.; Escudero, C.; Yanez, A.; Sobrevia, L.; Pastor Anglada, M.; Quezada, C.; San Martin, R.Up regulation of the transforming growth factor-beta 1 (TGF-beta 1) axis has been recognized as a pathogenic event for progression of glomerulosclerosis in diabetic nephropathy. We demonstrate that glomeruli isolated from diabetic rats accumulate up to sixfold more extracellular adenosine than normal rats. Both decreased nucleoside uptake activity by the equilibrative nucleoside transporter 1 and increased AMP hydrolysis contribute to raise extracellular adenosine. Ex vivo assays indicate that activation of the low affinity adenosine A(2B) receptor subtype (A(2B)AR) mediates TGF-beta 1 release from glomeruli of diabetic rats, a pathogenic event that could support progression of glomerulopathy when the bioavailability of adenosine is increased. (C) 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
- ItemAkt/mTOR Role in Human Foetoplacental Vascular Insulin Resistance in Diseases of Pregnancy(2017) Villalobos Labra, Roberto Esteban; Silva L; Subiabre Morales, Mario Enrique; Araos J; Salsoso Rodríguez, M. Rocío; Fuenzalida Saavedra, Bárbara; Sáez, Tamara; Toledo F; Leiva Mendoza, Andrea Alejandra; Sobrevía Luarte, Luis Alberto; Gonzalez, M.; Quezada, C.; Pardo, F.; Chiarello, Di
- ItemDesarrollo de la granulación durante la maduración de naranjas de ombligo tardías en la Zona Central de Chile(2000) Ortúzar, Juan E.; Barrales V., Luis; Peña Neira, Alvaro Iván; Carmona Morales, Patricia; Valdivieso Gatica, Gonzalo; Quezada, C.
- ItemHypoxia-reduced nitric oxide synthase activity is partially explained by higher arginase-2 activity and cellular redistribution in human umbilical vein endothelium(W B SAUNDERS CO LTD, 2011) Prieto, C. P.; Krause, B. J.; Quezada, C.; San Martin, R.; Sobrevia, L.; Casanello, P.Hypoxia relates with altered placental vasodilation, and in isolated endothelial cells, it reduces activity of the endothelial nitric oxide synthase (eNOS) and L-arginine transport. It has been reported that arginase-2 expression, an alternative pathway for L-arginine metabolism, is increased in adult endothelial cells exposed to hypoxia as well as in pre-eclamptic placentae. We studied in human umbilical vein endothelial cells (HUVEC) whether hypoxia-reduced NO synthesis results from increased arginase-mediated L-arginine metabolism and changes in subcellular localization of eNOS and arginase-2. In HUVEC exposed (24 h) to 5% (normoxia) or 2% (hypoxia) oxygen, L-arginine transport kinetics, arginase activity (urea assay), and NO synthase (NOS) activity (L-citrulline assay) were determined. Arginase-1, arginase-2 and eNOS expression were determined by RT-PCR and Western blot. Subcellular localization of arginase-2 and eNOS were studied using confocal microscopy and indirect immunofluorescence. Experiments were done in absence or presence of S-(2-boronoethyl)-L-cysteine-HCl (BEC, arginase inhibitor) or N-G-nitro-L-arginine methyl ester (L-NAME). Hypoxia-induced reduction in eNOS activity was associated with a reduction in eNOS phosphorylation at Serine-1177 and increased phosphorylation at Threonine-495. This was paralleled with an induction in arginase-2 expression and activity, and decreased L-arginine transport. In hypoxia the arginase inhibition, restored NO synthesis and L-arginine transport, without changes in the eNOS post-translational modification status. Hypoxia increased arginase-2/eNOS colocalization, and eNOS redistribution to the cell periphery. Altogether these data reinforce the thought that eNOS cell location, post-translational modification and substrate availability are important mechanisms regulating eNOS activity. If these mechanisms occur in pregnancy diseases where feto-placental oxygen levels are reduced remains to be clarified. (C) 2011 Elsevier Ltd. All rights reserved.
- ItemInterfacial behavior of PAMAM-PCL dendrimers and in situ spontaneous formation of gold nanoparticles at the toluene-water and air-water interfaces: Experimental and theoretical studies(2016) Saldías, César; Méndez Lesser, Manuel; Saavedra, M.; Pereira, A.; Rojas, M.; Avila, F.; Bonardd Salvador, Sebastián Ignacio; Pino, M.; Saldías, S.; Quezada, C.; Leiva, A.; Radić Foschino, Deodato D.
- ItemMultidrug resistance in glioblastoma stem-like cells: Role of the hypoxic microenvironment and adenosine signaling(2017) Uribe, D.; Torres, A.; Rocha, J.; Niechi, I.; Oyarzun, C.; Sobrevía Luarte, Luis Alberto; San Martin, R.; Quezada, C.
- ItemNueva normalidad, vieja precariedad : la crisis pandémica en Santiago de Chile(2020) Di Giminiani, Piergiorgio; Pérez, M.; Quezada, C.