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1.
Phys Chem Chem Phys ; 18(24): 16237-44, 2016 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-27251452

RESUMEN

ZnO nanoparticles (NPs) synthesized by pulsed laser ablation (PLAL) of a zinc plate in deionized water were investigated by time-resolved photoluminescence (PL) and complementary techniques (TEM, AFM, µRaman). HRTEM images show that PLAL produces crystalline ZnO NPs in wurtzite structure with a slightly distorted lattice parameter a. Consistently, optical spectra show the typical absorption edge of wurtzite ZnO (Eg = 3.38 eV) and the related excitonic PL peaked at 3.32 eV with a subnanosecond lifetime. ZnO NPs display a further PL peaking at 2.2 eV related to defects, which shows a power law decay kinetics. Thermal annealing in O2 and in a He atmosphere produces a reduction of the A1(LO) Raman mode at 565 cm(-1) associated with oxygen vacancies, accompanied by a decrease of defect-related emission at 2.2 eV. Based on our experimental results the emission at 2.2 eV is proposed to originate from a photo-generated hole in the valence band recombining with an electron deeply trapped in a singly ionized oxygen vacancy. This investigation clarifies important aspects of the photophysics of ZnO NPs and indicates that ZnO emission can be controlled by thermal annealing, which is important in view of optoelectronic applications.

2.
Nat Chem Biol ; 11(5): 347-354, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25848931

RESUMEN

Huntington's disease (HD) is a currently incurable neurodegenerative condition caused by an abnormally expanded polyglutamine tract in huntingtin (HTT). We identified new modifiers of mutant HTT toxicity by performing a large-scale 'druggable genome' siRNA screen in human cultured cells, followed by hit validation in Drosophila. We focused on glutaminyl cyclase (QPCT), which had one of the strongest effects on mutant HTT-induced toxicity and aggregation in the cell-based siRNA screen and also rescued these phenotypes in Drosophila. We found that QPCT inhibition induced the levels of the molecular chaperone αB-crystallin and reduced the aggregation of diverse proteins. We generated new QPCT inhibitors using in silico methods followed by in vitro screening, which rescued the HD-related phenotypes in cell, Drosophila and zebrafish HD models. Our data reveal a new HD druggable target affecting mutant HTT aggregation and provide proof of principle for a discovery pipeline from druggable genome screen to drug development.


Asunto(s)
Aminoaciltransferasas/efectos de los fármacos , Aminoaciltransferasas/genética , Enfermedad de Huntington/tratamiento farmacológico , Enfermedad de Huntington/genética , ARN Interferente Pequeño , Aminoaciltransferasas/antagonistas & inhibidores , Animales , Células Cultivadas , Biología Computacional , Drosophila , Evaluación Preclínica de Medicamentos , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/uso terapéutico , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Proteína Huntingtina , Ratones , Ratones Endogámicos C57BL , Mutación/genética , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Pez Cebra , Cadena B de alfa-Cristalina/metabolismo
3.
Kidney Int ; 64(1): 216-25, 2003 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12787412

RESUMEN

BACKGROUND: In ischemic acute renal failure (ARF), nitric oxide-dependent regulation of renal hemodynamics and glomerular function is disturbed. Previous studies indicate that the nitric oxide precursor l-arginine (l-Arg) has beneficial effects on renal function. Here we further analyzed the impact of l-Arg on functional and biochemical parameters of nitric oxide signaling during the course of ischemic ARF. METHODS: Ischemic ARF was induced in rats by bilateral clamping of renal arteries for 45 minutes. l-Arg was applied intraperitoneally during clamping, and orally during 14 days of follow-up. Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured, and biochemical parameters analyzed by protein immunoblots. RESULTS: Clamping resulted in 70% to 90% reduction of GFR and RPF, with a gradual recovery by day 14. Using an in situ assay with the oxidative fluorescent dye hydroethidine, increased tubular generation of O2- was detected in the early course of ischemic ARF, indicating enhanced oxidative stress. These findings were accompanied by up-regulation of the nitric oxide receptor, soluble guanylate cyclase, and by significant regulatory changes of inducible nitric oxide synthase (iNOS) and endothelial NOS expression. l-Arg had a beneficial effect on GFR and RPF, decreased O2- production, diminished up-regulation of soluble guanylate cyclase, and prevented up-regulation of iNOS. CONCLUSION: Ischemic ARF is accompanied by marked alterations in the expression of key enzymes of the nitric oxide pathway, indicative for deficiency of constitutive NOS activity. l-Arg supplementation reduces O2- generation and significantly improves the expression of nitric oxide signaling proteins as well as the recovery phase of ischemic ARF.


Asunto(s)
Lesión Renal Aguda/etiología , Lesión Renal Aguda/fisiopatología , Arginina/farmacología , Isquemia/complicaciones , Óxido Nítrico/deficiencia , Circulación Renal , Lesión Renal Aguda/metabolismo , Animales , Arginina/sangre , Presión Sanguínea/efectos de los fármacos , Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Femenino , Tasa de Filtración Glomerular/efectos de los fármacos , Guanilato Ciclasa/metabolismo , Semivida , Óxido Nítrico Sintasa/metabolismo , Ratas , Ratas Sprague-Dawley , Recuperación de la Función , Circulación Renal/efectos de los fármacos , Solubilidad , Superóxidos/metabolismo
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