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1.
Sci Rep ; 12(1): 5154, 2022 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-35338208

RESUMEN

This work presents a feasible design of an integrated photonic circuit performing as a device for single-qubit preparation and rotations through the third-order nonlinear process of difference frequency generation (DFG) and defined in the temporal mode basis. The first stage of our circuit includes the generation of heralded single photons by spontaneous four-wave mixing in a micro-ring cavity engineered for delivering a single-photon state in a unique temporal mode. The second stage comprises the implementation of DFG in a spiral waveguide with controlled dispersion properties for reaching color qubit preparation fidelity close to unity. We present the generalized rotation operator related to the DFG process, a methodology for the device design, and qubit preparation fidelity results as a function of user-accessible parameters.

2.
Neotrop Entomol ; 47(5): 698-708, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29484545

RESUMEN

The lesser mealworm, Alphitobius diaperinus (Panzer), is the main insect pest in the poultry industry, thus causing serious damage to production. In this work, the properties of midgut α-amylase from larvae of A. diaperinus were characterized, and its in vitro activity to proteinaceous preparations from different cultivars of common bean (Phaseolus vulgaris) was determined, as well as the amylolitic activity of insects reared on different types of poultry diet. In order to establish some assay conditions, time course and enzyme concentration upon the reaction rate were determined. Product proceeded linearly with time, and the activity was directly proportional to the enzyme concentration. Banding patterns in mildly denaturing electrophoresis showed a single band with apparent molecular weight of 42 kDa. α-Amylase reached optimal temperature at 45°C and pH 5.0 as the optimal one. It maintained 34.6% of the activity after being kept at 60°C for 5 min, and 23%, after 60 min. However, at 80°C, only 14 and 6% remained after 5 and 60 min, respectively. The presence of Ca2+ and Na+ ions decreased the enzyme activity at concentrations higher than 2 and 100 mM, respectively. The activity was significantly inhibited by some proteinaceous extracts from common bean cultivars, and it declined with increasing proteinaceous concentration. No significant difference was observed when the amylolytic activity was determined in A. diaperinus reared on different poultry diets, offered to broilers in the starter, grower, finisher, and layer phases.


Asunto(s)
Alimentación Animal/parasitología , Escarabajos/enzimología , Sistema Digestivo/enzimología , alfa-Amilasas/química , Animales , Inhibidores Enzimáticos/química , Estabilidad de Enzimas , Larva/enzimología , Phaseolus/química , Aves de Corral , alfa-Amilasas/antagonistas & inhibidores
3.
Medimay ; 26(1)ene. 2018. tab
Artículo en Español | CUMED | ID: cum-74706

RESUMEN

Introducción: la familia es la célula elemental de la sociedad, donde sus integrantes satisfacen sus intereses afectivos y sociales, pero a menudo se ve afectada por la presencia de violencia. Objetivo: evaluar los conocimientos que sobre violencia intrafamiliar y maltrato infantil tienen las familias disfuncionales antes y después de una estrategia de intervención. Métodos: se realizó una investigación tipo cuasi experimental antes y después sin grupo control de las familias disfuncionales pertenecientes al consultorio número 11 del Policlínico Docente Marta Martínez Figuera ubicado en Güines, Mayabeque, en el periodo comprendido entre el mes de febrero del año 2015 a mayo del año 2017. El universo de estudio estuvo conformado por 245 familias, la muestra fue de 178 familias disfuncionales. Resultados: antes de la intervención los resultados encontrados evidenciaron que la ingestión de alcohol fue la condición en el medio familiar más asociada a violencia, los golpes y/o castigos físicos fueron la principal manifestación de maltrato infantil, la persona del núcleo que más propició el maltrato fue la madre, los niños hipercinéticos fueron los más vulnerables y reconocieron el maltrato físico como forma más frecuente. Después de la intervención, se evidenciaron los gritos y/o amenazas verbales como principal manifestación de maltrato infantil, los niños rebeldes a la disciplina son los más afectados y la forma más relevante fue el maltrato psicológico y/o emocional. Conclusiones: antes de la intervención existían escasos conocimientos relacionados con la violencia intrafamiliar y el maltrato infantil, ganándose estos, después de la estrategia de intervención(AU)


Introduction: the family is the main cell of the society, where its members satisfy the affective and social interests, but sometimes it is affected by the presence of violence. Objective: to evaluate knowledge about intrafamily violence, and children abuse that dysfunctional families have before and after an intervention strategy.Methods: a cuasi experimental investigation before and after without control group of dysfunctional families from Doctor's Office # 11 at "Marta Martinez Figuera" teaching policlinic located in Güines, Mayabeque, was performed from February, 2015 to May, 2017. The universe was formed by 245 families; the sample was of 178 dysfunctional families. Results: before the intervention, the found results evidenced that alcohol ingestion was the most associated condition to violence within the families, bumps and physical punishments were the main manifestations of children abuse, the person from the household that most favored the abuse was their mothers, hyperactive children were the most vulnerable and recognized the physical abuse as the most frequent cause. After the intervention, shouts and verbal intimidations resulted as the main manifestations of children abuse, rebelled children to discipline are the most affected and the most relevant were the psychological and/or emotional abuse. Conclusions: before the interventions there were insufficient knowledge related to intrafamily violence and children abuse, and they were improved after the intervention strategy(AU)


Asunto(s)
Humanos , Masculino , Femenino , Lactante , Preescolar , Niño , Adolescente , Maltrato Conyugal , Familia , Violencia Doméstica , Conflicto Familiar , Relaciones Familiares , Maltrato a los Niños/ética , Violencia Doméstica/prevención & control , Estudios Controlados Antes y Después/métodos , Educación de la Población
4.
Neuroscience ; 317: 149-61, 2016 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-26791522

RESUMEN

Streptococcus pneumoniae is the causative agent of numerous diseases including severe invasive infections such as bacteremia and meningitis. It has been previously shown that strains of S. pneumoniae that are unable to survive in the bloodstream may colonize the CNS. However, information on cellular components and pathways involved in the neurotropism of these strains is still scarce. The olfactory system is a specialized tissue in which olfactory receptor neurons (ORNs) are interfacing with the external environment through several microvilli. Olfactory ensheathing cells (OECs) which also form the glial limiting membrane at the surface of the olfactory bulb (OB) are the only cells that ensheathe the ORNs axons. Since previous data from our group showed that OECs may harbor S. pneumoniae, we decided to test whether infection of the OB or OEC cultures modulates the expression levels of neurotrophic factor's mRNA and its putative effects on the activation and viability of microglia. We observed that neurotrophin-3 (NT-3) and glial cell-line-derived neurotrophic factor (GDNF) expression was significantly higher in the OB from uninfected mice than in infected mice. A similar result was observed when we infected OEC cultures. Brain-derived neurotrophic factor (BNDF) expression was significantly lower in the OB from infected mice than in uninfected mice. In contrast, in vitro infection of OECs resulted in a significant increase of BDNF mRNA expression. An upregulation of high-mobility group box 1 (HMGB1) expression was observed in both OB and OEC cultures infected with S. pneumoniae. Moreover, we found that conditioned medium from infected OEC cultures induced the expression of the pro-apoptotic protein cleaved-caspase-3 and an apparently continuous nuclear factor-kappa B (NF-κB) p65 activation in the N13 microglia. Altogether, our data suggest the possible existence of an OEC-pathogen molecular interface, through which the OECs could interfere on the activation and viability of microglia, favoring the access of non-hematogenous S. pneumoniae strains to the CNS in the absence of bacteremia.


Asunto(s)
Factores de Crecimiento Nervioso/metabolismo , Neuroglía/metabolismo , Bulbo Olfatorio/metabolismo , Bulbo Olfatorio/patología , Infecciones Neumocócicas/patología , 2',3'-Nucleótido Cíclico Fosfodiesterasas/metabolismo , Actinas/metabolismo , Animales , Caspasa 3/metabolismo , Células Cultivadas , Modelos Animales de Enfermedad , Regulación Bacteriana de la Expresión Génica/fisiología , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Modelos Biológicos , N-Acetil Muramoil-L-Alanina Amidasa/genética , N-Acetil Muramoil-L-Alanina Amidasa/metabolismo , FN-kappa B/metabolismo , Factores de Crecimiento Nervioso/genética , Neuroglía/microbiología , ARN Mensajero/metabolismo
5.
Metallomics ; 7(5): 743-7, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25860559

RESUMEN

Disruptions of biometal-Aß(1-40) interactions by an isoniazid-derived hydrazone, INHHQ, were demonstrated via in vitro NMR titrations. The compound has adequate theoretical BBB absorption properties, assessed by in silico studies. In vivo acute toxicity assays indicate that INHHQ is innocuous up to 300 mg kg(-1), showing potential as an anti-Alzheimer's drug.


Asunto(s)
Péptidos beta-Amiloides/metabolismo , Cobre/metabolismo , Hidrazonas/química , Hidrazonas/farmacología , Isoniazida/análogos & derivados , Isoniazida/farmacología , Fragmentos de Péptidos/metabolismo , Zinc/metabolismo , Enfermedad de Alzheimer/tratamiento farmacológico , Animales , Barrera Hematoencefálica/metabolismo , Homeostasis/efectos de los fármacos , Humanos , Hidrazonas/farmacocinética , Isoniazida/farmacocinética , Masculino , Ratas Wistar
6.
Photochem Photobiol Sci ; 14(3): 536-42, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25337907

RESUMEN

In this work, nitrogen-doped ZnO material was synthesized by the sol-gel method using zinc acetate as the precursor and urea as the nitrogen source (15, 20, 25 and 30% wt.). For comparative purposes, bare ZnO was also prepared. The influence of N doping on structural, morphological, optical and photocatalytic properties was investigated. The synthesized catalysts were characterized by XRD, SEM-EDS, diffuse reflectance UV-Vis spectroscopy, BET and XPS analysis. The photocatalytic activity of N-doped ZnO catalysts was evaluated during the degradation of a mixture of herbicides (2,4-D and picloram) under visible radiation ≥400 nm. The photo-absorption wavelength range of the N-doped ZnO samples was shifted to longer wavelength compared to those of the unmodified ZnO. Among different amounts of dopant agent, the 30% N-doped ZnO material showed higher visible-light activity compared with pure ZnO. Several degradation by-products were identified by using HPLC and ESI-MS/MS. The enhancement of visible photocatalytic activity of the N-doped ZnO semiconductor could be mainly due to their capability in reducing the electron-hole pair recombination.


Asunto(s)
Ácido 2,4-Diclorofenoxiacético/química , Herbicidas/química , Nitrógeno/química , Procesos Fotoquímicos , Picloram/química , Óxido de Zinc/química , Óxido de Zinc/síntesis química , Catálisis , Técnicas de Química Sintética
7.
J Sports Med Phys Fitness ; 54(4): 403-9, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25034544

RESUMEN

BACKGROUND: The aim of this study was to analyze the relationship between the isokinetic shoulder strength of the athletes and their performance on strength field tests. Data on the balance and functional strength ratios of the internal and external rotator muscles of shoulders of handball players was also investigated. METHODS: Twenty-seven female athletes (23±3.4 years, 71±10.6 kg and 173.3±7.1 cm) underwent an isokinetic assessment of the strength of the shoulder rotator muscles. Athletes also performed the following strength field tests: bench press test, lying bench barbell row test, handgrip test, and medicine ball throwing. RESULTS: The bench press test results and the lying bench barbell row test results were significantly correlated with the concentric internal and external rotator peak torques at 1.05 rad.s-1 and 5.23 rad.s-1, with total work at 1.05 rad.s-1 and with average power at 5.23 rad.s-1 (r=0.51 to 0.81). CONCLUSION: We suggested the use of field test to infer about internal and external rotator muscular strength, but not to infer about isokinetic muscular strength ratios. These findings could be useful to coaches and trainers.


Asunto(s)
Fuerza Muscular/fisiología , Manguito de los Rotadores/fisiología , Deportes/fisiología , Adulto , Prueba de Esfuerzo/métodos , Femenino , Fuerza de la Mano , Humanos , Levantamiento de Peso , Adulto Joven
8.
Science ; 344(6184): 620-3, 2014 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-24812399

RESUMEN

The regenerative power of tissues and organs in biology has no analog in synthetic materials. Although self-healing of microscopic defects has been demonstrated, the regrowth of material lost through catastrophic damage requires a regenerative-like approach. We demonstrate a vascular synthetic system that restores mechanical performance in response to large-scale damage. Gap-filling scaffolds are created through a two-stage polymer chemistry that initially forms a shape-conforming dynamic gel but later polymerizes to a solid structural polymer with robust mechanical properties. Through the control of reaction kinetics and vascular delivery rate, we filled impacted regions that exceed 35 mm in diameter within 20 min and restored mechanical function within 3 hours. After restoration of impact damage, 62% of the total absorbed energy was recovered in comparison with that in initial impact tests.


Asunto(s)
Polimerizacion , Polímeros/química , Regeneración , Geles/química , Cinética , Fenómenos Mecánicos , Modelos Químicos
10.
J Inherit Metab Dis ; 35(3): 425-30, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22076426

RESUMEN

INTRODUCTION: Individuals with phenylketonuria (PKU, OMIM 261600) have shown bone disease from childhood. Factors such as non-adherence to treatment, nutritional inadequacy, and high phenylalanine levels are associated with bone disease in several studies. This research aimed to describe the impact of dietary factors (consumption of energy, protein, calcium, phosphorus, and phenylalanine), and the control of plasma phenylalanine levels on bone age (BA) and bone mineral density (BMD). METHODOLOGY: Thirteen patients of both genders, from 8 to 16 years old participated in this study. Control data were collected of phenylalanine levels, food frequency and record, hand and fist X-rays, and spinal bone densitometry. RESULTS: In children group (CG), individuals non-adherent to diet (NAD) consumed lower amounts of calcium (472 ± 100 mg/day) and energy (1743 ± 486 Kcal); they had higher rates of phenylalanine (564 ± 94 µmol/L) in blood, intake phenylalanine (701 ± 334 mg/g), and higher protein intake from free foods (14 ± 6.67 g/day); bone age (BA) values higher than the chronological age (CA) and less BMD values (-0.7 ± 1.6 SD) also were verified. In adolescent group (AG, N = 8) of NAD, values were lower for energy intake (1379 ± 258 Kcal), calcium (801 ± 152 mg/day), phosphorus (657 ± 102 mg/day), food protein (25 ± 7.6 g/day), and intake phenylalanine (1067 ± 382 mg/day) than recommended. Higher levels of plasma phenylalanine (851 ± 244 µmol/L), bone age greater than chronological age and lower BMD values (-2.4 ± -2.5 SD) were observed. CONCLUSION: The results suggest effects on BA and on BMD, in both children and adolescent groups. The bone development is expressed differently in children and adolescents. The non-adherence to the diet verified in both groups and the consequent imbalance in the nutrients intake involved in bone metabolism suggest that these factors influence the failure to thrive in children and reduced bone mineralization in adolescents.


Asunto(s)
Desarrollo Óseo , Fenilcetonurias/genética , Adolescente , Densidad Ósea , Huesos/patología , Niño , Trastornos de la Nutrición del Niño/genética , Ciencias de la Nutrición del Niño , Densitometría/métodos , Dieta , Ingestión de Energía , Femenino , Humanos , Masculino , Cooperación del Paciente , Fenilalanina/análisis , Fenilalanina/sangre , Fenilcetonurias/fisiopatología , Rayos X
11.
J Nanosci Nanotechnol ; 11(6): 5574-9, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21770221

RESUMEN

ZnO nanoparticles ranging from 2 to 10 nm were grown on ZSM-5 and mordenite zeolite hosts with different SiO2/Al2O3 molar ratios (MR). Formation of ZnO nanoparticles in the samples was confirmed by TEM. XRD and nitrogen adsorption measurements revealed that the zeolite structure is not destroyed. Surface Zn concentration was calculated from XPS data. ZnO nanoparticles in the zeolite matrix were studied by UV-Vis, diffuse reflectance and cathodoluminescence (CL) spectroscopies. CL revealed three different emissions from ZnO nanoparticles, approximately 3.1, 2.8 and 2.5 eV. The ZnO band-edge emission was associated with blue defects-related and oxygen vacancies emissions. The generation of the point defects at the interface explains the presence of this blue band.

14.
Immunol Invest ; 36(4): 473-92, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17691027

RESUMEN

A technique developed in Trypanosoma cruzi biochemical studies was successfully used to fractionate Leishmania (Leishmania) amazonensis promastigotes. Ultrastructural analyses revealed a membrane fraction (MF) associated to subpellicular microtubules, a ribosomal-rich microsomal fraction (MicF), and a flagellar fraction (FF) free of associated membrane. All fractions proved to be immunogenic through delayed type hypersensitivity reaction assays. Therefore, a protocol was designed to test whether these fractions could elicit a protective response in mice infected by L. (L), amazonensis. The protocol consisted of a BCG injection (as cellular immunity inducer), followed by cyclophosphamide (once its cytotoxic effect is over, this immunosuppressor can increase the number of circulating leukocytes), then an injection with one of the fractions followed by a challenge. When compared to infected control animals, mice injected with any of the fractions presented a smaller footpad swelling, especially those injected with MicF or FF. Macroscopically, immunized mice under modulation by BCG presented no swelling. Histopathological studies performed on day 120 revealed fewer amastigotes and more intense inflammation in lesions of MicF and FF injected mice. Animals injected with MF presented an intermediate pattern. Parasite quantification corroborated these results. The results show that all fractions are potent immunostimulators, but MicF and FF have the strongest protective ability.


Asunto(s)
Antígenos de Protozoos/inmunología , Leishmania/inmunología , Leishmaniasis/inmunología , Vacunas Antiprotozoos/inmunología , Animales , Anticuerpos Antiprotozoarios/inmunología , Femenino , Leishmania/patogenicidad , Leishmaniasis/parasitología , Ratones , Fracciones Subcelulares/inmunología , Fracciones Subcelulares/ultraestructura
16.
Genet Mol Res ; 5(3): 553-63, 2006 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-17117371

RESUMEN

In a 17-kb genomic fragment of Trypanosoma cruzi chromosome XX, we identified three tandemly linked genes coding for CX(2)CX(4)HX(4)C zinc finger proteins. We also showed that similar genes are present in T. brucei and Leishmania major, sharing three monophyletic groups among these trypanosomatids. In T. cruzi, TcZFP8 corresponds to a novel gene coding for a protein containing eight zinc finger motifs. Molecular cloning of this gene and heterologous expression as a fusion with a His-tag were performed in Escherichia coli. The purified recombinant protein was used to produce antibody in rabbits. Using Western blot analysis, we observed the presence of this protein in all three forms of the parasite: amastigote, trypomastigote and epimastigote. An analysis of cytoplasmic and nuclear cell extracts showed that this protein is present in nuclear extracts, and indirect immunofluorescence microscopy confirmed the nuclear localization of TcZFP8. Homologues of TcZFP8 in T. brucei are apparently absent, while one candidate in L. major was identified.


Asunto(s)
Núcleo Celular/metabolismo , Código Genético/genética , Proteínas Protozoarias/genética , Trypanosoma cruzi/genética , Dedos de Zinc/genética , Animales , Secuencia de Bases , Western Blotting , Clonación Molecular , ADN Protozoario/genética , ADN Protozoario/metabolismo , Técnica del Anticuerpo Fluorescente Indirecta , Microscopía Fluorescente , Datos de Secuencia Molecular , Proteínas Protozoarias/metabolismo , ARN Protozoario/genética , ARN Protozoario/metabolismo , Conejos , Trypanosoma cruzi/metabolismo
17.
Genet. mol. res. (Online) ; 5(3): 553-563, 2006. ilus, graf
Artículo en Inglés | LILACS | ID: lil-441051

RESUMEN

In a 17-kb genomic fragment of Trypanosoma cruzi chromosome XX, we identified three tandemly linked genes coding for CX2CX4HX4C zinc finger proteins. We also showed that similar genes are present in T. brucei and Leishmania major, sharing three monophyletic groups among these trypanosomatids. In T. cruzi, TcZFP8 corresponds to a novel gene coding for a protein containing eight zinc finger motifs. Molecular cloning of this gene and heterologous expression as a fusion with a His-tag were performed in Escherichia coli. The purified recombinant protein was used to produce antibody in rabbits. Using Western blot analysis, we observed the presence of this protein in all three forms of the parasite: amastigote, trypomastigote and epimastigote. An analysis of cytoplasmic and nuclear cell extracts showed that this protein is present in nuclear extracts, and indirect immunofluorescence microscopy confirmed the nuclear localization of TcZFP8. Homologues of TcZFP8 in T. brucei are apparently absent, while one candidate in L. major was identified.


Asunto(s)
Animales , Conejos , Núcleo Celular/metabolismo , Código Genético/genética , Proteínas Protozoarias/genética , Trypanosoma cruzi/genética , Dedos de Zinc/genética , Secuencia de Bases , Western Blotting , Clonación Molecular , ADN Protozoario/genética , ADN Protozoario/metabolismo , Técnica del Anticuerpo Fluorescente Indirecta , Microscopía Fluorescente , Datos de Secuencia Molecular , Proteínas Protozoarias/metabolismo , ARN Protozoario/genética , ARN Protozoario/metabolismo , Trypanosoma cruzi/metabolismo
18.
J Nanosci Nanotechnol ; 2(1): 101-5, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-12908328

RESUMEN

We report the study of aurothiol nanoclusters using high-resolution electron microscopy, energy loss spectroscopy, X-ray photoelectron spectroscopy, Auger spectroscopy, and microscopy. It is concluded that the sulfur atoms are located on the surface of the gold nanoparticles in both (100) and (111) microfacets. The X-ray photoelectron spectroscopy data show that there is a Au-Au bond as well as a Au-S bond. Auger depth profile measurements made by sputtering of the nanoparticles corroborates that the sulfur is located on the surface of the nanoparticle. Quantitative Auger analysis indicates a ratio Au/S between approximately 1.79 and 1.98.


Asunto(s)
Nanotecnología/métodos , Compuestos de Sulfhidrilo/química , Azufre/química , Sitios de Unión , Cristalografía/métodos , Sustancias Macromoleculares , Ensayo de Materiales/métodos , Microscopía Electrónica , Modelos Moleculares , Conformación Molecular , Tamaño de la Partícula , Espectrometría por Rayos X , Compuestos de Sulfhidrilo/síntesis química , Propiedades de Superficie
19.
J Biol Chem ; 276(35): 32933-9, 2001 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-11402050

RESUMEN

Baculovirus P35 is a universal suppressor of apoptosis that stoichiometrically inhibits cellular caspases in a novel cleavage-dependent mechanism. Upon caspase cleavage at Asp-87, the 10- and 25-kDa cleavage products of P35 remain tightly associated with the inhibited caspase. Mutations in the alpha-helix of the reactive site loop preceding the cleavage site abrogate caspase inhibition and antiapoptotic activity. Substitution of Pro for Val-71, which is located in the middle of this alpha-helix, produces a protein that is cleaved at the requisite Asp-87 but does not remain bound to the caspase. This loss-of-function mutation provided the opportunity to structurally analyze the conformational changes of the P35 reactive site loop after caspase cleavage. We report here the 2.7 A resolution crystal structure of V71P-mutated P35 after cleavage by human caspase-3. The structure reveals a large movement in the carboxyl-terminal side of the reactive site loop that swings down and forms a new beta-strand that augments an existing beta-sheet. Additionally, the hydrophobic amino terminus releases and extends away from the protein core. Similar movements occur when P35 forms an inhibitory complex with human caspase-8. These findings suggest that the alpha-helix mutation may alter the sequential steps or kinetics of the conformational changes required for inhibition, thereby causing P35 loss of function.


Asunto(s)
Caspasas/metabolismo , Proteínas Virales/química , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Apoptosis/fisiología , Ácido Aspártico , Baculoviridae , Sitios de Unión , Cristalografía por Rayos X , Proteínas Inhibidoras de la Apoptosis , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Nucleopoliedrovirus , Conformación Proteica , Estructura Secundaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Virales/metabolismo
20.
Diabetes ; 50(2): 353-60, 2001 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11272147

RESUMEN

Recent findings have demonstrated that the branched-chain amino acid leucine can activate the translational regulators, phosphorylated heat- and acid-stable protein regulated by insulin (PHAS-I) and p70 S6 kinase (p70S6k), in an insulin-independent and rapamycin-sensitive manner through mammalian target of rapamycin (mTOR), although the mechanism for this activation is undefined. It has been previously established that leucine-induced insulin secretion by beta-cells involves increased mitochondrial metabolism by oxidative decarboxylation and allosteric activation of glutamate dehydrogenase (GDH). We now show that these same intramitochondrial events that generate signals for leucine-induced insulin exocytosis are required to activate the mTOR mitogenic signaling pathway by beta-cells. Thus, a minimal model consisting of leucine and glutamine as substrates for oxidative decarboxylation and an activator of GDH, respectively, confirmed the requirement for these two metabolic components and mimicked closely the synergistic interactions achieved by a complete complement of amino acids to activate p70s6k in a rapamycin-sensitive manner. Studies using various leucine analogs also confirmed the close association of mitochondrial metabolism and the ability of leucine analogs to activate p70s6k. Furthermore, selective inhibitors of mitochondrial function blocked this activation in a reversible manner, which was not associated with a global reduction in ATP levels. These findings indicate that leucine at physiological concentrations stimulates p70s6k phosphorylation via the mTOR pathway, in part, by serving both as a mitochondrial fuel and an allosteric activator of GDH. Leucine-mediated activation of protein translation through mTOR may contribute to enhanced beta-cell function by stimulating growth-related protein synthesis and proliferation associated with the maintenance of beta-cell mass.


Asunto(s)
Islotes Pancreáticos/fisiología , Leucina/fisiología , Fosfotransferasas (Aceptor de Grupo Alcohol)/fisiología , Biosíntesis de Proteínas/fisiología , Proteínas Quinasas , Regulación Alostérica , Aminoácidos Cíclicos/farmacología , Línea Celular , Descarboxilación , Activación Enzimática , Glutamato Deshidrogenasa/metabolismo , Ácido Glutámico/fisiología , Islotes Pancreáticos/citología , Isoleucina/farmacología , Leucina/metabolismo , Leucina/farmacología , Mitocondrias/fisiología , Modelos Biológicos , Oxidación-Reducción , Fosforilación , Proteínas Quinasas S6 Ribosómicas/metabolismo , Transducción de Señal/fisiología , Serina-Treonina Quinasas TOR , Valina/farmacología
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