Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 30
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
J Cell Physiol ; 234(12): 22921-22934, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31148189

RESUMEN

Bax triggers cell apoptosis by permeabilizing the outer mitochondrial membrane, leading to membrane potential loss and cytochrome c release. However, it is unclear if proteasomal degradation of Bax is involved in the apoptotic process, especially in heart ischemia-reperfusion (I/R)-induced injury. In the present study, KPC1 expression was heightened in left ventricular cardiomyocytes of patients with coronary heart disease (CHD), in I/R-myocardium in vivo and in hypoxia and reoxygenation (H/R)-induced cardiomyocytes in vitro. Overexpression of KPC1 reduced infarction size and cell apoptosis in I/R rat hearts. Similarly, the forced expression of KPC1 restored mitochondrial membrane potential (MMP) and cytochrome c release driven by H/R in H9c2 cells, whereas reducing cell apoptosis, and knockdown of KPC1 by short-hairpin RNA (shRNA) deteriorated cell apoptosis induced by H/R. Mechanistically, forced expression of KPC1 promoted Bax protein degradation, which was abolished by proteasome inhibitor MG132, suggesting that KPC1 promoted proteasomal degradation of Bax. Furthermore, KPC1 prevented basal and apoptotic stress-induced Bax translocation to mitochondria. Bax can be a novel target for the antiapoptotic effects of KPC1 on I/R-induced cardiomyocyte apoptosis and render mechanistic penetration into at least a subset of the mitochondrial effects of KPC1.


Asunto(s)
Enfermedad Coronaria/genética , Mitocondrias/genética , Complejos de Ubiquitina-Proteína Ligasa/genética , Proteína X Asociada a bcl-2/genética , Animales , Apoptosis/genética , Hipoxia de la Célula/genética , Supervivencia Celular/genética , Enfermedad Coronaria/patología , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Humanos , Potencial de la Membrana Mitocondrial/genética , Mitocondrias/metabolismo , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Proteolisis , Ratas , Transducción de Señal/genética
2.
Cell Physiol Biochem ; 48(2): 433-449, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30016789

RESUMEN

BACKGROUND/AIMS: Vagus nerve stimulation (VNS) suppresses arrhythmic activity and minimizes cardiomyocyte injury. However, how VNS affects angiogenesis/arteriogenesis in infarcted hearts, is poorly understood. METHODS: Myocardial infarction (MI) was achieved by ligation of the left anterior descending coronary artery (LAD) in rats. 7 days after LAD, stainless-steel wires were looped around the left and right vagal nerve in the neck for vagus nerve stimulation (VNS). The vagal nerve was stimulated with regular pulses of 0.2ms duration at 20 Hz for 10 seconds every minute for 4 hours, and then ACh levels by ELISA in cardiac tissue and serum were evaluated for its release after VNS. Three and 14 days after VNS, Real-time PCR, immunostaining and western blot were respectively used to determine VEGF-A/B expressions and α-SMA- and CD31-postive vessels in VNS-hearts with pretreatment of α7-nAChR blocker mecamylamine (10 mg/kg, ip) or mACh-R blocker atropine (10 mg/kg, ip) for 1 hour. The coronary function and left ventricular performance were analyzed by Langendorff system and hemodynamic parameters in VNS-hearts with pretreatment of VEGF-A/B-knockdown or VEGFR blocker AMG706. Coronary arterial endothelial cells proliferation, migration and tube formation were evaluated for angiogenesis following the stimulation of VNS in coronary arterial smooth muscle cells (VSMCs). RESULTS: VNS has been shown to stimulate VEGF-A and VEGF-B expressions in coronary arterial smooth muscle cells (VSMCs) and endothelial cells (ECs) with an increase of α-SMA- and CD31-postive vessel number in infarcted hearts. The VNS-induced VEGF-A/B expressions and angiogenesis were abolished by m-AChR inhibitor atropine and α7-nAChR blocker mecamylamine in vivo. Interestingly, knockdown of VEGF-A by shRNA mainly reduced VNS-mediated formation of CD31+ microvessels. In contrast, knockdown of VEGF-B powerfully abrogated VNS-induced formation of α-SMA+ vessels. Consistently, VNS-induced VEGF-A showed a greater effect on EC tube formation as compared to VNS-induced VEGF-B. Moreover, VEGF-A promoted EC proliferation and VSMC migration while VEGF-B induced VSMC proliferation and EC migration in vitro. Mechanistically, vagal neurotransmitter acetylcholine stimulated VEGF-A/B expressions through m/nACh-R/PI3K/Akt/Sp1 pathway in EC. Functionally, VNS improved the coronary function and left ventricular performance. However, blockade of VEGF receptor by antagonist AMG706 or knockdown of VEGF-A or VEGF-B by shRNA significantly diminished the beneficial effects of VNS on ventricular performance. CONCLUSION: VNS promoted angiogenesis/arteriogenesis to repair the infracted heart through the synergistic effects of VEGF-A and VEGF-B.


Asunto(s)
Infarto del Miocardio/terapia , Estimulación del Nervio Vago , Factor A de Crecimiento Endotelial Vascular/metabolismo , Factor B de Crecimiento Endotelial Vascular/metabolismo , Acetilcolina/análisis , Acetilcolina/sangre , Animales , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Indoles/farmacología , Masculino , Microvasos/citología , Microvasos/efectos de los fármacos , Microvasos/metabolismo , Músculo Liso Vascular/citología , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/metabolismo , Infarto del Miocardio/patología , Miocardio/metabolismo , Niacinamida/administración & dosificación , Niacinamida/farmacología , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Interferencia de ARN , ARN Interferente Pequeño/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Muscarínicos/química , Receptores Muscarínicos/metabolismo , Factor A de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Factor A de Crecimiento Endotelial Vascular/genética , Factor B de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Factor B de Crecimiento Endotelial Vascular/genética , Receptor Nicotínico de Acetilcolina alfa 7/antagonistas & inhibidores , Receptor Nicotínico de Acetilcolina alfa 7/metabolismo
3.
Biochim Biophys Acta Mol Basis Dis ; 1863(11): 2772-2782, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28693920

RESUMEN

S100B is a biomarker of nervous system injury, but it is unknown if it is also involved in vascular injury. In the present study, we investigated S100B function in vascular remodeling following injury. Balloon injury in rat carotid artery progressively induced neointima formation while increasing S100B expression in both neointimal vascular smooth muscle (VSMC) and serum along with an induction of proliferating cell nuclear antigen (PCNA). Knockdown of S100B by its shRNA delivered by adenoviral transduction attenuated the PCNA expression and neointimal hyperplasia in vivo and suppressed PDGF-BB-induced VSMC proliferation and migration in vitro. Conversely, overexpression of S100B promoted VSMC proliferation and migration. Mechanistically, S100B altered VSMC phenotype by decreasing the contractile protein expression, which appeared to be mediated by NF-κB activity. S100B induced NF-κB-p65 gene transcription, protein expression and nuclear translocation. Blockade of NF-κB activity by its inhibitor reversed S100B-mediated downregulation of VSMC contractile protein and increase in VSMC proliferation and migration. It appeared that S100B regulated NF-κB expression through, at least partially, the Receptor for Advanced Glycation End products (RAGE) because RAGE inhibitor attenuated S100B-mediated NF-κB promoter activity as well as VSMC proliferation. Most importantly, S100B secreted from VSMC impaired endothelial tube formation in vitro, and knockdown of S100B promoted re-endothelialization of injury-denuded arteries in vivo. These data indicated that S100B is a novel regulator for vascular remodeling following injury and may serve as a potential biomarker for vascular damage or drug target for treating proliferative vascular diseases.


Asunto(s)
Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/metabolismo , Neointima/metabolismo , Subunidad beta de la Proteína de Unión al Calcio S100/biosíntesis , Remodelación Vascular , Animales , Regulación de la Expresión Génica , Músculo Liso Vascular/lesiones , Músculo Liso Vascular/patología , Miocitos del Músculo Liso/patología , Neointima/patología , Ratas , Ratas Sprague-Dawley , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Factor de Transcripción ReIA/metabolismo
4.
Mol Cell Biochem ; 413(1-2): 9-23, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26769665

RESUMEN

VEGF-C is a newly identified proangiogenic protein playing an important role in vascular disease and angiogenesis. However, its role in myocardial ischemia/reperfusion (I/R) injury remains unknown. The objective of this study was to determine the role and mechanism of VEGF-C in myocardial ischemia-reperfusion injury. Rat left ventricle myocardium was injected with recombinant human VEGF-C protein (0.1 or 1.0 µg/kg b.w.) 1 h prior to myocardial ischemia-reperfusion (I/R) injury. 24 h later, the myocardial infarction size, the number of TUNEL-positive cardiomyocytes, the levels of creatine kinase (CK), CK-MB, cardiac troponin, malondialdehyde (MDA) content, and apoptosis protein Bax expression were decreased, while Bcl2 and pAkt expression were increased in VEGF-C-treated myocardium as compared to the saline-treated I/R hearts. VEGF-C also improved the function of I/R-injured hearts. In the H2O2-induced H9c2 cardiomyocytes, which mimicked the I/R injury in vivo, VEGF-C pre-treatment decreased the LDH release and MDA content, blocked H2O2-induced apoptosis by inhibiting the pro-apoptotic protein Bax expression and its translocation to the mitochondrial membrane, and consequently attenuated H2O2-induced decrease of mitochondrial membrane potential and increase of cytochrome c release from mitochondria. Mechanistically, VEGF-C activated Akt signaling pathway via VEGF receptor 2, leading to a blockade of Bax expression and mitochondrial membrane translocation and thus protected cardiomyocyte from H2O2-induced activation of intrinsic apoptotic pathway. VEGF-C exerts its cardiac protection following I/R injury via its anti-apoptotic effect.


Asunto(s)
Cardiotónicos/administración & dosificación , Daño por Reperfusión Miocárdica/prevención & control , Miocitos Cardíacos/citología , Factor C de Crecimiento Endotelial Vascular/administración & dosificación , Animales , Apoptosis/efectos de los fármacos , Cardiotónicos/farmacología , Línea Celular , Modelos Animales de Enfermedad , Humanos , Peróxido de Hidrógeno/farmacología , L-Lactato Deshidrogenasa/metabolismo , Malondialdehído/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacología , Transducción de Señal/efectos de los fármacos , Factor C de Crecimiento Endotelial Vascular/farmacología
5.
BMC Cardiovasc Disord ; 15: 116, 2015 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-26446519

RESUMEN

BACKGROUND: Oxidative stress is closely associated with cardiac fibrosis. However, the effect of copper, zinc-superoxide dismutase (SOD1) as a therapeutic agent is limited due to the insufficient transduction. This study was aimed to investigate the effect of PEP-1-SOD1 fusion protein on angiotensin II (ANG II)-induced collagen metabolism in rat cardiac myofibroblasts (MCFs). METHODS: MCFs were pretreated with SOD1 or PEP-1-SOD1 fusion protein for 2 h followed by incubation with ANG II for 24 h. Cell proliferation was measured by Cell Counting Kit-8. Superoxide anion productions were detected by both fluorescent microscopy and Flow Cytometry. MMP-1 and TIMP-1 were determined by ELISA. Intracellular MDA content and SOD activity were examined by commercial assay kits. Protein expression was analyzed by western blotting. RESULTS: PEP-1-SOD1 fusion protein efficiently transduced into MCF, scavenged intracellular O2 (-), decreased intracellular MDA content, increased SOD activity, suppressed ANG II-induced proliferation, reduced expression of TGF-ß1, α-SMA, collagen type I and III, restored MMP-1 secretion, and attenuated TIMP-1 secretion. CONCLUSION: PEP-1-SOD1 suppressed MCF proliferation and differentiation and reduced production of collagen type I and III. Therefore, PEP-1-SOD1 fusion protein may be a potential novel therapeutic agent for cardiac fibrosis.


Asunto(s)
Colágeno Tipo III/metabolismo , Colágeno Tipo I/metabolismo , Cisteamina/análogos & derivados , Miofibroblastos/metabolismo , Péptidos/farmacología , Superóxido Dismutasa/farmacología , Angiotensina II , Animales , Proliferación Celular/efectos de los fármacos , Cisteamina/farmacología , Masculino , Malondialdehído/metabolismo , Metaloproteinasa 1 de la Matriz/metabolismo , Estrés Oxidativo/efectos de los fármacos , Ratas Sprague-Dawley , Superóxido Dismutasa-1 , Superóxidos/metabolismo , Inhibidor Tisular de Metaloproteinasa-1/metabolismo
6.
Carcinogenesis ; 34(8): 1806-14, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23563091

RESUMEN

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox- sensitive transcription factor regulating expression of a number of cytoprotective genes. Recently, Nrf2 has emerged as an important contributor to chemoresistance in cancer therapy. In the present study, we found that non-toxic dose of apigenin (APG) significantly sensitizes doxorubicin-resistant BEL-7402 (BEL-7402/ADM) cells to doxorubicin (ADM) and increases intracellular concentration of ADM. Mechanistically, APG dramatically reduced Nrf2 expression at both the messenger RNA and protein levels through downregulation of PI3K/Akt pathway, leading to a reduction of Nrf2-downstream genes. In BEL-7402 xenografts, APG and ADM cotreatment inhibited tumor growth, reduced cell proliferation and induced apoptosis more substantially when compared with ADM treatment alone. These results clearly demonstrate that APG can be used as an effective adjuvant sensitizer to prevent chemoresistance by downregulating Nrf2 signaling pathway.


Asunto(s)
Apigenina/farmacología , Carcinoma Hepatocelular/tratamiento farmacológico , Doxorrubicina/farmacología , Resistencia a Antineoplásicos/efectos de los fármacos , Neoplasias Hepáticas/tratamiento farmacológico , Factor 2 Relacionado con NF-E2/antagonistas & inhibidores , Inhibidores de las Quinasa Fosfoinosítidos-3 , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Animales , Apoptosis/efectos de los fármacos , Apoptosis/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Regulación hacia Abajo/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/genética , Distribución Aleatoria , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Ensayos Antitumor por Modelo de Xenoinjerto
7.
J Transl Med ; 11: 113, 2013 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-23642335

RESUMEN

BACKGROUND: Catalase (CAT) breaks down H2O2 into H2O and O2 to protects cells from oxidative damage. However, its translational potential is limited because exogenous CAT cannot enter living cells automatically. This study is aimed to investigate if PEP-1-CAT fusion protein can effectively protect cardiomyocytes from oxidative stress due to hypoxia/reoxygenation (H/R)-induced injury. METHODS: H9c2 cardomyocytes were pretreated with catalase (CAT) or PEP-1-CAT fusion protein followed by culturing in a hypoxia and re-oxygenation condition. Cell apoptosis were measured by Annexin V and PI double staining and Flow cytometry. Intracellular superoxide anion level was determined, and mitochondrial membrane potential was measured. Expression of apoptosis-related proteins including Bcl-2, Bax, Caspase-3, PARP, p38 and phospho-p38 was analyzed by western blotting. RESULTS: PEP-1-CAT protected H9c2 from H/R-induced morphological alteration and reduced the release of lactate dehydrogenase (LDH) and malondialdehyde content. Superoxide anion production was also decreased. In addition, PEP-1-CAT inhibited H9c2 apoptosis and blocked the expression of apoptosis stimulator Bax while increased the expression of Bcl-2, leading to an increased mitochondrial membrane potential. Mechanistically, PEP-1-CAT inhibited p38 MAPK while activating PI3K/Akt and Erk1/2 signaling pathways, resulting in blockade of Bcl2/Bax/mitochondrial apoptotic pathway. CONCLUSION: Our study has revealed a novel mechanism by which PEP-1-CAT protects cardiomyocyte from H/R-induced injury. PEP-1-CAT blocks Bcl2/Bax/mitochondrial apoptotic pathway by inhibiting p38 MAPK while activating PI3K/Akt and Erk1/2 signaling pathways.


Asunto(s)
Apoptosis , Catalasa/metabolismo , Miocitos Cardíacos/patología , Oxígeno/metabolismo , Péptidos/metabolismo , Transducción de Señal , Aniones/metabolismo , Hipoxia de la Célula , Línea Celular , Citometría de Flujo , Humanos , Peróxido de Hidrógeno/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Malondialdehído/metabolismo , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , Estrés Oxidativo , Proteínas Recombinantes de Fusión/metabolismo , Superóxidos/metabolismo
8.
J Cell Biochem ; 113(8): 2704-13, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22441978

RESUMEN

Acetylcholine (ACh) plays an important role in neural and non-neural function, but its role in mesenchymal stem cell (MSC) migration remains to be determined. In the present study, we have found that ACh induces MSC migration via muscarinic acetylcholine receptors (mAChRs). Among several mAChRs, MSCs express mAChR subtype 1 (m1AChR). ACh induces MSC migration via interaction with mAChR1. MEK1/2 inhibitor PD98059 blocks ERK1/2 phosphorylation while partially inhibiting the ACh-induced MSC migration. InsP3Rs inhibitor 2-APB that inhibits MAPK/ERK phosphorylation completely blocks ACh-mediated MSC migration. Interestingly, intracellular Ca(2+) ATPase-specific inhibitor thapsigargin also completely blocks ACh-induced MSC migration through the depletion of intracellular Ca(2+) storage. PKCα or PKCß inhibitor or their siRNAs only partially inhibit ACh-induced MSC migration, but PKC-ζ siRNA completely inhibits ACh-induced MSC migration via blocking ERK1/2 phosphorylation. These results indicate that ACh induces MSC migration via Ca(2+), PKC, and ERK1/2 signal pathways.


Asunto(s)
Acetilcolina/farmacología , Calcio/metabolismo , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Células Madre Mesenquimatosas/citología , Proteína Quinasa C/metabolismo , Animales , Western Blotting , Movimiento Celular/fisiología , Proliferación Celular/efectos de los fármacos , Masculino , Células Madre Mesenquimatosas/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Receptores Muscarínicos/metabolismo , Transducción de Señal/efectos de los fármacos
9.
Mol Biol Rep ; 39(5): 5085-93, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22161247

RESUMEN

Vascular endothelial growth factor (VEGF) plays a crucial role in tumor angiogenesis. VEGF induces new vessel formation and tumor growth by inducing mitogenesis and chemotaxis of normal endothelial cells and increasing vascular permeability. However, little is known about VEGF function in the proliferation, survival or migration of hepatocellular carcinoma cells (HCC). In the present study, we have found that VEGF receptors are expressed in HCC line BEL7402 and human HCC specimens. Importantly, VEGF receptor expression correlates with the development of the carcinoma. By using a comprehensive approaches including TUNEL assay, transwell and wound healing assays, migration and invasion assays, adhesion assay, western blot and quantitative RT-PCR, we have shown that knockdown of VEGF165 expression by shRNA inhibits the proliferation, migration, survival and adhesion ability of BEL7402. Knockdown of VEGF165 decreased the expression of NF-κB p65 and PKCα while increased the expression of p53 signaling molecules, suggesting that VEGF functions in HCC proliferation and migration are mediated by P65, PKCα and/or p53.


Asunto(s)
Carcinoma Hepatocelular/patología , Movimiento Celular , Neoplasias Hepáticas/patología , Factor A de Crecimiento Endotelial Vascular/metabolismo , Carcinoma Hepatocelular/enzimología , Adhesión Celular , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular , Humanos , Neoplasias Hepáticas/enzimología , Invasividad Neoplásica , Proteína Quinasa C-alfa/metabolismo , ARN Interferente Pequeño/metabolismo , Receptores de Factores de Crecimiento Endotelial Vascular/metabolismo , Proteína p53 Supresora de Tumor/metabolismo
10.
J Transl Med ; 9: 73, 2011 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-21600015

RESUMEN

BACKGROUND: Our previous studies indicate that either PEP-1-superoxide dismutase 1 (SOD1) or PEP-1-catalase (CAT) fusion proteins protects myocardium from ischemia-reperfusion-induced injury in rats. The aim of this study is to explore whether combined use of PEP-1-SOD1 and PEP-1-CAT enhances their protective effects. METHODS: SOD1, PEP-1-SOD1, CAT or PEP-1-CAT fusion proteins were prepared and purified by genetic engineering. In vitro and in vivo effects of these proteins on cell apoptosis and the protection of myocardium after ischemia-reperfusion injury were measured. Embryo cardiac myocyte H9c2 cells were used for the in vitro studies. In vitro cellular injury was determined by the expression of lactate dehydrogenase (LDH). Cell apoptosis was quantitatively assessed with Annexin V and PI double staining by Flow cytometry. In vivo, rat left anterior descending coronary artery (LAD) was ligated for one hour followed by two hours of reperfusion. Hemodynamics was then measured. Myocardial infarct size was evaluated by TTC staining. Serum levels of myocardial markers, creatine kinase-MB (CK-MB) and cTnT were quantified by ELISA. Bcl-2 and Bax expression in left ventricle myocardium were analyzed by western blot. RESULTS: In vitro, PEP-1-SOD1 or PEP-1-CAT inhibited LDH release and apoptosis rate of H9c2 cells. Combined transduction of PEP-1-SOD1 and PEP-1-CAT, however, further reduced the LDH level and apoptosis rate. In vivo, combined usage of PEP-1-SOD1 and PEP-1-CAT produced a greater effect than individual proteins on the reduction of CK-MB, cTnT, apoptosis rate, lipoxidation end product malondialdehyde, and the infarct size of myocardium. Functionally, the combination of these two proteins further increased left ventricle systolic pressure, but decreased left ventricle end-diastolic pressure. CONCLUSION: This study provided a basis for the treatment or prevention of myocardial ischemia-reperfusion injury with the combined usage of PEP-1-SOD1 and PEP-1-CAT fusion proteins.


Asunto(s)
Cardiotónicos/metabolismo , Catalasa/genética , Péptidos de Penetración Celular/metabolismo , Daño por Reperfusión Miocárdica/prevención & control , Miocardio/patología , Superóxido Dismutasa/genética , Transducción Genética , Animales , Apoptosis , Catalasa/metabolismo , Creatina Quinasa/sangre , Hemodinámica/fisiología , L-Lactato Deshidrogenasa/metabolismo , Malondialdehído/metabolismo , Infarto del Miocardio/complicaciones , Infarto del Miocardio/patología , Infarto del Miocardio/fisiopatología , Daño por Reperfusión Miocárdica/complicaciones , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Miocardio/enzimología , Ratas , Proteínas Recombinantes de Fusión/aislamiento & purificación , Superóxido Dismutasa/metabolismo , Troponina T/sangre , Función Ventricular Izquierda/fisiología , Proteína X Asociada a bcl-2/metabolismo
11.
JAMA Netw Open ; 4(10): e2127587, 2021 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-34596673

RESUMEN

Importance: Angiotensin II is significantly associated with the pathogenesis of acute aortic dissection. Angiotensin II type 1 receptor agonistic autoantibodies (AT1-AAs) can mimic the effect of angiotensin II. Objective: To investigate the association between AT1-AAs and all-cause and cause-specific mortality risk in patients with acute aortic dissection. Design, Setting, and Participants: A total of 662 patients with clinically suspected aortic dissection from 3 medical centers in Wuhan, China, were enrolled in this cohort study from August 1, 2014, to July 31, 2016. Of these, 315 patients were included in the 3-year follow-up study. Follow-up was mainly performed via telephone interviews and outpatient clinic visits. Data analysis was conducted from March 1 to May 31, 2020. Main Outcomes and Measures: The primary outcomes of interest were all-cause mortality, death due to aortic dissection, and late aortic-related adverse events. Results: The full study cohort included 315 patients with AAD (mean [SD] age, 56.2 [12.7] years; 230 men [73.0%]). Ninety-two patients (29.2%) were positive for AT1-AAs. The mortality of AT1-AA-positive patients was significantly higher than that of AT1-AA-negative patients (40 [43.5%] vs 37 [16.6%]; P < .001). The mortality risk in AT1-AA-positive patients was always significantly higher than that in AT1-AA-negative patients in patients with both type A and type B dissection. Multivariable analysis showed that the risk of AT1-AA-positive patients for type A dissection was significantly higher than that of AT1-AA-negative patients (odds ratio [OR], 1.88; 95% CI, 1.12-3.13; P = .02). The Cox proportional hazards regression model showed a significant increase of all-cause mortality risk (OR, 2.27; 95% CI, 1.44-3.57; P < .001) and late aortic-related adverse events (OR, 1.58; 95% CI, 1.06-2.36; P = .03) among AT1-AA-positive patients during the follow-up period compared with AT1-AA-negative patients. Conclusions and Relevance: This cohort study first detected AT1-AAs in patients with acute aortic dissection. The presence of AT1-AAs was associated with significantly higher all-cause and cause-specific mortality during a follow-up period of 3 years. The antibodies may be a risk factor for aortic dissection.


Asunto(s)
Bloqueadores del Receptor Tipo 1 de Angiotensina II/administración & dosificación , Disección Aórtica/complicaciones , Evaluación de Resultado en la Atención de Salud/estadística & datos numéricos , Anciano , Disección Aórtica/epidemiología , Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Autoanticuerpos/análisis , Autoanticuerpos/sangre , China/epidemiología , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Evaluación de Resultado en la Atención de Salud/métodos , Modelos de Riesgos Proporcionales
12.
Zhongguo Gu Shang ; 33(3): 261-4, 2020 Mar 25.
Artículo en Zh | MEDLINE | ID: mdl-32233256

RESUMEN

OBJECTIVE: To explore clinical effects of platelet rich plasma (PRP) injection in treating atrophic fracture nonunion. METHODS: From March 2015 to March 2017, 15 patients with atrophic fracture nonunion were treated with PRP injection, including 10 males and 5 females, aged from 23 to 56 years old with an average age of (40.0±9.1) years old, the time of fracture nonunion ranged from 6 to 14 months with an average of (8.87±2.45) months. Preparing PRP by extracting 60 to 100 ml peripheral blood. PRP platelet count ranged from 587 to 1 246 with an average of (947.13±158.58) ×10 9 /L. Under the perspective, 13 to 20 ml PRP were injected into the fracture end, and each injection was performed once on the first and the second week of the treatment. Complications such as whether the limb was shortened, angulation, and rotational deformity and radiological examination were observed. RESULTS: All patients were followed up from 6 to 12 months with an average of (6.8± 2.1) months. No shortening, angulation, and rotational deformity occurred. Thirteen patients had fracture healing, the time ranged from 4 to 6 months with an average of (4.8±0.7) months. Two patients had no completely porosis at 12 months during following up, and 1 patient occurred bolt loose. Other patients had no complications. CONCLUSION: The stability of fracture ends of atrophic fracture nonunion after internal fixation is an indication for local PRP injection. PRP treatment for atrophic fractures could completed under local anesthesia, and it has advantages of safe operation and reliable efficacy.


Asunto(s)
Fracturas no Consolidadas , Adulto , Femenino , Fijación Interna de Fracturas , Curación de Fractura , Fracturas no Consolidadas/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Plasma Rico en Plaquetas , Resultado del Tratamiento , Adulto Joven
13.
Mol Cells ; 27(2): 159-66, 2009 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-19277497

RESUMEN

Myocardial ischemia-reperfusion injury is a medical problem occurring as damage to the myocardium following blood flow restoration after a critical period of coronary occlusion. Oxygen free radicals (OFR) are implicated in reperfusion injury after myocardial ischemia. The antioxidant enzyme, Cu, Zn-superoxide dismutase (Cu, Zn-SOD, also called SOD1) is one of the major means by which cells counteract the deleterious effects of OFR after ischemia. Recently, we reported that a PEP-1-SOD1 fusion protein was efficiently delivered into cultured cells and isolated rat hearts with ischemia-reperfusion injury. In the present study, we investigated the protective effects of the PEP-1-SOD1 fusion protein after ischemic insult. Immunofluorescecnce analysis revealed that the expressed and purified PEP-1-SOD1 fusion protein injected into rat tail veins was efficiently transduced into the myocardium with its native protein structure intact. When injected into Sprague-Dawley rat tail veins, the PEP-1- SOD1 fusion protein significantly attenuated myocardial ischemia-reperfusion damage; characterized by improving cardiac function of the left ventricle, decreasing infarct size, reducing the level of malondialdehyde (MDA), decreasing the release of creatine kinase (CK) and lactate dehydrogenase (LDH), and relieving cardiomyocyte apoptosis. These results suggest that the biologically active intact forms of PEP-1-SOD1 fusion protein will provide an efficient strategy for therapeutic delivery in various diseases related to SOD1 or to OFR.


Asunto(s)
Cisteamina/análogos & derivados , Daño por Reperfusión Miocárdica/prevención & control , Miocardio/enzimología , Péptidos/metabolismo , Proteínas Recombinantes de Fusión/administración & dosificación , Superóxido Dismutasa/metabolismo , Animales , Apoptosis , Creatina Quinasa/metabolismo , Cisteamina/metabolismo , Técnica del Anticuerpo Fluorescente , L-Lactato Deshidrogenasa/metabolismo , Masculino , Malondialdehído/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Miocardio/patología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Estrés Oxidativo , Ratas , Ratas Sprague-Dawley , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa-1
14.
Zhonghua Xin Xue Guan Bing Za Zhi ; 37(3): 268-74, 2009 Mar.
Artículo en Zh | MEDLINE | ID: mdl-19781155

RESUMEN

OBJECTIVE: The transduction efficiency of the purified PEP-1-SOD1 fusion protein and the effects of PEP-1-SOD1 fusion protein on ischemia reperfusion injury in the isolated perfused rat hearts were investigated. METHODS: The constructed pET15b-SOD1 and pET15b-PEP-1-SOD1 were transformed into BL21 (DE3) for expression and purification of SOD1 and PEP-1-SOD1, respectively. Isolated perfused rat hearts were subjected to 60 min of global ischemia and 30 min of reperfusion and treated with vehicle, 100 micromol/L SOD1 and 25, 50, 100 micromol/L PEP-1-SOD1, respectively. The transduction efficiency was evaluated with immunofluorescent microscopy and Western blot. The enzyme activity of the transduced PEP-1-SOD1 was measured with commercial SOD detection kit. The MDA content in myocardial tissue and the CK activity in coronary exudate at 15 min after reperfusion were also measured. Cardiomyocyte apoptosis was detected with TUNEL. The infarct size was determined in isolated hearts 60 min after reperfusion with TTC staining. RESULTS: Immunofluorescent microscopy and Western blot demonstrated PEP-1-SOD1 was transduced into myocardial tissue in a dose-dependent manner, whereas SOD1 could not be detected in SOD1 group. SOD activity in control, SOD1 group, 25, 50, 100 micromol/L PEP-1-SOD1 groups was (10.06 +/- 0.77) U/mg prot, (10.59 +/- 0.71) U/mg prot, (32.29 +/- 1.42) U/mg prot, (43.16 +/- 1.16) U/mg prot, (55.14 +/- 1.59) U/mg prot, respectively. MDA content in corresponding groups was (1.48 +/- 0.19) nmol/mg prot, (1.39 +/- 0.11) nmol/mg prot, (1.01 +/- 0.14) nmol/mg prot, (0.73 +/- 0.13) nmol/mg prot, (0.50 +/- 0.06) nmol/mg prot, respectively. CK activity in corresponding groups was (1.73 +/- 0.58) U/mg prot,(1.68 +/- 0.14) U/mg prot,(1.40 +/- 0.28) U/mg prot,(0.97 +/- 0.39) U/mg prot, (0.61 +/- 0.56) U/mg prot, respectively. Cardiomyocyte apoptotic index in corresponding groups was (17.25 +/- 0.75)%, (16.63 +/- 1.07)%, (11.50 +/- 0.57) U/mg prot, (6.50 +/- 0.63) U/mg prot, (4.13 +/- 0.52)%, repectively. The percentage of myocardial infarction area was (55.13 +/- 2.18)%, (52.13 +/- 2.59)%, (33.88 +/- 2.06)%, (25.50 +/- 2.16)%, (15.38 +/- 1.14)%, respectively. Compared with control group and SOD1 group, all P < 0.01 These results demonstrated the enzyme activity of the transduced PEP-1-SOD1 was significantly increased in a dose-dependent manner and the MDA content, CK activity, the cardiomyocyte apoptotic index and the infarct size was decreased siginificantly in PEP-1-SOD1 pretreatment groups compared with SOD1 group. CONCLUSION: The native, biologically active form of PEP-SOD1 fusion protein could be effectively transduced into the isolated rat hearts subjecting ischemia reperfusion injury in a dose-dependent manner. The transduced PEP-1-SOD1 has protective effects on ischemia reperfusion injury in the isolated rat hearts.


Asunto(s)
Miocardio , Daño por Reperfusión , Animales , Apoptosis/efectos de los fármacos , Corazón , Infarto del Miocardio , Daño por Reperfusión Miocárdica/metabolismo , Miocardio/metabolismo , Ratas , Ratas Sprague-Dawley
15.
Math Biosci Eng ; 16(5): 5687-5696, 2019 06 19.
Artículo en Inglés | MEDLINE | ID: mdl-31499732

RESUMEN

Background: The current standard approach to the treatment of patients with non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI)-sensitizing mutations has been the treatment with a first-generation EGFR-TKIs. While, with resistance developed against first-generation EGFR-TKIs, second/third-generation TKIs have attracted all the attention, and replaced first-generation EGFR- TKIs upon disease progression due to the greater efficacy and more favorable tolerability. In the past few years, this strategy has been challenged by clinical evidence when next-generation EGFR-TKIs are used in patients with advanced NSCLC. Objective: In this study, we performed a meta- analysis to investigate the efficacy of next-generation TKIs comparison with first-generation TKIs in the treatment of NSCLC. Methods: The multiple databases including Pubmed, Embase, Cochrane library databases were adopted to search for the relevant studies, and full-text articles involving to comparison of next-generation TKIs and first-generation TKIs were reviewed. After rigorous reviewing on quality, the data was extracted from eligible randomized controlled trial (RCT). Meta-analysis Revman 5.3 software was used to analyze the combined pooled ORs with the corresponding 95% confidence interval using fixed- or random-effects models according to the heterogeneity. Results: A total of 5 randomized controlled trials were included in this analysis. The group of next-generation TKIs did achieved benefit in progression-free survival (PFS) (OR = 0.58, 95%CI = 0.45-0.75, P<0.0001), overall survival (OS) (OR = 0.76, 95%CI = 0.65-0.90, P = 0.001) as well with the objective response rate (ORR) (OR = 1.27, 95%CI = 1.01-1.61, P = 0.04), respectively. In the results of subgroup analysis of PFS with EGFR mutations, there is also significant differences with exon 19 deletion (OR = 0.56, 95%CI = 0.41-0.77, P = 0.0003) and exon 21 (L858R) mutation (OR = 0.60, 95%CI = 0.49-0.75, P<=0.00001). While, the treatment-related severe adverse event (SAE) between the next-generation TKIs and first-generation TKIs did not have statistical significance (OR = 1.48, 95%CI = 0.62-3.55, P = 0.38). Conclusion: The next-generation TKIs significantly improved efficacy outcomes in the treatment of EGFR mutation-positive advanced NSCLC compared with the first-generation TKIs, with a manageable safety profile. These results are potentially important for clinical decision making for these patients.


Asunto(s)
Antineoplásicos/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Supervivencia sin Enfermedad , Diseño de Fármacos , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/genética , Exones , Humanos , Neoplasias Pulmonares/mortalidad , Mutación , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento
16.
Data Brief ; 16: 266-270, 2018 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-29204471

RESUMEN

In the previous report, Meox1 was found to promote SMCs phenotypic modulation and injury-induced vascular remodeling by regulating the FAK-ERK1/2-autophagy signaling cascade (Wu et al., 2017) [1]. Here, we presented new original data on the involvement of Mesoderm/mesenchyme homeobox gene l (Meox1) in balloon-injury-induced neointima formation of rat. In rat carotid artery balloon injury model to induce vascular remodeling, Meox1 was induced in vascular smooth muscle cell (SMCs) of rat carotid arteries. Most proliferating cell nuclear antigen (PCNA)-positive cells also expressed Meox1. These data suggested that Meox1 may be involved in SMCs proliferation during injury-induced neointima formation. Furthermore, knocked down its expression in injured arteries by adenoviral delivery of Meox1 short hairpin RNA (shRNA) (shMeox1), neointima formation was significantly inhibited. Elastin staining also confirmed the reduction of neointima in Meox1 shRNA-transduced arteries. Moreover, knockdown of Meox1 decreased the collagen production/deposition that was significantly increased in neointima induced by balloon injury.

17.
Int J Cardiol ; 251: 82-89, 2018 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-29113690

RESUMEN

AIMS: To investigate the role of mesoderm/mesenchyme homeobox gene l (Meox1) in vascular smooth muscle cells (SMCs) phenotypic modulation during vascular remodeling. METHODS AND RESULTS: By using immunostaining, Western blot, and histological analyses, we found that Meox1 was up-regulated in PDGF-BB-treated SMCs in vitro and balloon injury-induced arterial SMCs in vivo. Meox1 knockdown by shRNA restored the expression of contractile SMCs phenotype markers including smooth muscle α-actin (α-SMA) and calponin. In contrast, overexpression of Moex1 inhibited α-SMA and calponin expressions while inducing the expressions of synthetic SMCs phenotype markers such as matrix gla protein, osteopontin, and proliferating cell nuclear antigen. Mechanistically, Meox1 mediated the SMCs phenotypic modulation through FAK-ERK1/2 signaling, which appears to induce autophagy in SMCs. In vivo, knockdown of Meox1 attenuated injury-induced neointima formation and promoted SMCs contractile proteins expressions. Meox1 knockdown also reduced the number of proliferating SMCs, suggesting that Meox1 was important for SMCs proliferation in vivo. Moreover, knockdown of Meox1 attenuated ERK1/2 signaling and autophagy markers expressions, suggesting that Meox1 may promote SMCs phenotypic modulation via ERK1/2 signaling-autophagy in vivo. CONCLUSION: Our data indicated that Meox1 promotes SMCs phenotypic modulation and injury-induced vascular remodeling by regulating the FAK-ERK1/2-autophagy signaling cascade. Thus, targeting Meox1 may be an attractive approach for treating proliferating vascular diseases.


Asunto(s)
Músculo Liso Vascular/citología , Músculo Liso Vascular/fisiología , Fenotipo , Factores de Transcripción/deficiencia , Remodelación Vascular/fisiología , Animales , Movimiento Celular/efectos de los fármacos , Movimiento Celular/fisiología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Técnicas de Silenciamiento del Gen/métodos , Proteínas de Homeodominio , Masculino , Músculo Liso Vascular/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Factores de Transcripción/biosíntesis , Factores de Transcripción/farmacología , Remodelación Vascular/efectos de los fármacos
18.
Environ Pollut ; 220(Pt B): 990-996, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27876227

RESUMEN

Although previous studies showed that children are widely exposed to phthalates, the sources of phthalate exposure for school-aged children in China are not well understood. This study aimed to assess phthalate metabolite levels and explore the factors influencing exposure in children. We collected demographic data and biological samples from 336 children aged 6-12 years. We calculated urinary concentrations of 14 mono-phthalate metabolites and conducted chi-square (χ2) tests and logistic regression analysis to determine the variables associated with phthalate levels. Mono-n-butyl phthalate (MnBP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) were the most abundant urinary phthalate metabolites. In addition, housing type, decorating materials in the home, and frequency of canned food consumption were associated with exposure to low molecular weight phthalates. Water source, duration of time spent playing with toys, residential area, and frequency of canned food consumption were associated with exposure to high molecular weight phthalates. Based on these results, potential strategies to reduce exposure to phthalates include avoiding plastic food containers and chemical fragrances as well as eating fewer processed foods, especially canned foods, and foods in plastic packaging.


Asunto(s)
Exposición a Riesgos Ambientales/análisis , Ácidos Ftálicos/orina , Niño , China , Ingestión de Alimentos , Femenino , Humanos , Masculino , Peso Molecular , Ácidos Ftálicos/metabolismo , Plásticos
19.
Sci Total Environ ; 579: 950-956, 2017 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-27884522

RESUMEN

This study aimed to evaluate the associations between phthalate concentrations and thyroid function in preschool children. We collected demographic data and biological samples from 216 children aged 5-7years. We calculated urinary concentrations of eight mono-phthalate metabolites (mPAEs) separately for children from urban and rural areas and investigated their associations with thyroid function and growth hormones. mPAE concentrations were higher in children from the urban area than in those from the rural area, and most mPAEs were positively associated with free triiodothyronine and free thyroxine. The insulin-like growth factor 1 (IGF-1) concentration decreased 0.082ng/mL (95% confidence interval [CI]: -1.34, -0.113) with each 1ng/mL increase in monomethyl phthalate (MMP) and 0.132ng/mL (95% CI: -0.209, -0.055) with each 1ng/mL increase in mono-n-butyl phthalate. The insulin-like growth factor binding protein 3 concentration decreased by 0.01mg/L (95% CI: -0.001, -0.000) or 0.01mg/L (95% CI: -0.003, -0.000) with each 1ng/mL increase in MMP or monoethyl phthalate, respectively. Exposure to some phthalates at 5-7years of age might interfere with thyroid hormones and growth.


Asunto(s)
Exposición a Riesgos Ambientales/estadística & datos numéricos , Contaminantes Ambientales/metabolismo , Ácidos Ftálicos/metabolismo , Glándula Tiroides/fisiología , Niño , Preescolar , Femenino , Humanos , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Masculino , Ácidos Ftálicos/toxicidad , Glándula Tiroides/metabolismo , Hormonas Tiroideas/metabolismo
20.
Int J Cardiol ; 183: 221-31, 2015 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-25679991

RESUMEN

BACKGROUND: The objective of this study was to determine whether vascular endothelial growth factor (VEGF)-A subtypes improve cardiac stem cell (CSC) engraftment and promote CSC-mediated myocardial repair in the infarcted heart. METHODS: CSCs were treated with VEGF receptor (VEGFR) inhibitors, VCAM-1 antibody (VCAM-1-Ab), or PKC-α inhibitor followed by the treatment with VEGF-A. CSC adhesion assays were performed in vitro. In vivo, the PKH26-labeled and VCAM-1-Ab or PKC-α inhibitor pre-treated CSCs were treated with VEGF-A followed by implantation into infarcted rat hearts. The hearts were then collected for measuring CSC engraftment and evaluating cardiac fibrosis and function 3 or 28days after the CSC transplantation. RESULTS: All three VEGF-A subtypes promoted CSC adhesion to extracellular matrix and endothelial cells. VEGF-A-mediated CSC adhesion required VEGFR and PKCα signaling. Importantly, VEGF-A induced VCAM-1, but not ICAM-1 expression in CSCs through PKCα signaling. In vivo, VEGF-A promoted the engraftment of CSCs in infarcted hearts, which was attenuated by PKCα inhibitor or VCAM-1-Ab. Moreover, VEGF-A-mediated CSC engraftment resulted in a reduction in infarct size and fibrosis. Functional studies showed that the transplantation of the VEGF-A-treated CSCs stimulated extensive angiomyogenesis in infarcted hearts as indicated by the expression of cardiac troponin T and von Willebrand factor, leading to an improved performance of left ventricle. Blockade of PKCα signaling or VCAM-1 significantly diminished the beneficial effects of CSCs treated with VEGF-A. CONCLUSION: VEGF-A promotes myocardial repair through, at least in part, enhancing the engraftment of CSCs mediated by PKCα/VCAM-1 pathway.


Asunto(s)
Infarto del Miocardio/terapia , Trasplante de Células Madre/métodos , Células Madre/citología , Factor A de Crecimiento Endotelial Vascular/metabolismo , Animales , Modelos Animales de Enfermedad , Citometría de Flujo/métodos , Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Proteína Quinasa C-alfa/metabolismo , Proteínas Proto-Oncogénicas c-kit/genética , Proteínas Proto-Oncogénicas c-kit/metabolismo , Ratas , Ratas Sprague-Dawley , Regeneración/fisiología , Células Madre/metabolismo , Molécula 1 de Adhesión Celular Vascular/metabolismo , Factor A de Crecimiento Endotelial Vascular/uso terapéutico
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA