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1.
Nature ; 603(7900): 271-275, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35038718

RESUMEN

In oxidation reactions catalysed by supported metal nanoparticles with oxygen as the terminal oxidant, the rate of the oxygen reduction can be a limiting factor. This is exemplified by the oxidative dehydrogenation of alcohols, an important class of reactions with modern commercial applications1-3. Supported gold nanoparticles are highly active for the dehydrogenation of the alcohol to an aldehyde4 but are less effective for oxygen reduction5,6. By contrast, supported palladium nanoparticles offer high efficacy for oxygen reduction5,6. This imbalance can be overcome by alloying gold with palladium, which gives enhanced activity to both reactions7,8,9; however, the electrochemical potential of the alloy is a compromise between that of the two metals, meaning that although the oxygen reduction can be improved in the alloy, the dehydrogenation activity is often limited. Here we show that by separating the gold and palladium components in bimetallic carbon-supported catalysts, we can almost double the reaction rate compared with that achieved with the corresponding alloy catalyst. We demonstrate this using physical mixtures of carbon-supported monometallic gold and palladium catalysts and a bimetallic catalyst comprising separated gold and palladium regions. Furthermore, we demonstrate electrochemically that this enhancement is attributable to the coupling of separate redox processes occurring at isolated gold and palladium sites. The discovery of this catalytic effect-a cooperative redox enhancement-offers an approach to the design of multicomponent heterogeneous catalysts.


Asunto(s)
Oro , Nanopartículas del Metal , Alcoholes , Aleaciones , Carbono , Catálisis , Oxidación-Reducción , Oxígeno , Paladio
2.
Nano Lett ; 24(15): 4602-4609, 2024 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-38567988

RESUMEN

Oxygen vacancy (OV) engineering has been widely applied in different types of metal oxide-based photocatalytic reactions. Our study has shown that the redistributed OVs resulting from voids in CeO2 rods lead to significant differences in the band structure in space. The flat energy band within the highly crystallized bulk region hinders the recombination of photogenerated carrier pairs during the transfer process. The downward curved energy band in the surface region enhances the activation of the absorbents. Therefore, the localization of the band structure through crystal structure regionalization renders V-CeO2 capable of achieving efficient utilization of photogenerated carriers. Practically, the V-CeO2 rod shows a remarkable turnover number of 190.58 µmol g-1 h-1 in CO2 photoreduction, which is ∼9.4 times higher than that of D-CeO2 (20.46 µmol g-1 h-1). The designed modularization structure in our work is expected to provide important inspiration and guidance in coordinating the kinetic behavior of carriers in OV defect-rich photocatalysts.

3.
Brain Cogn ; 177: 106167, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38704903

RESUMEN

Although previous research has shown that social power modulates individuals' sensitivity to rewards, it is currently unclear whether social power increases or decreases individuals' sensitivity to rewards. This study employed event-related potentials (ERPs) to investigate the effects of social power on individuals' neural responses to monetary and social rewards. Specifically, participants underwent an episodic priming task to manipulate social power (high-power vs. low-power) and then completed monetary and social delayed incentive tasks while their behavioral responses and electroencephalograms (EEG) were recorded. According to ERP analysis, during the anticipatory stage, low-power individuals exhibited a greater cue-P3 amplitude than high-power individuals in both monetary and social tasks. In the consummatory stage, though no impact of social power on the reward positivity (RewP) was found, low-power individuals showed a higher feedback-P3 (FB-P3) amplitude than high-power individuals, regardless of task types (the MID and SID tasks). In conclusion, these results provide evidence that social power might decrease one's sensitivity to monetary and social rewards in both the anticipatory and consummatory stages.


Asunto(s)
Electroencefalografía , Potenciales Evocados , Recompensa , Humanos , Masculino , Femenino , Electroencefalografía/métodos , Adulto Joven , Potenciales Evocados/fisiología , Adulto , Poder Psicológico , Encéfalo/fisiología , Motivación/fisiología , Anticipación Psicológica/fisiología , Conducta Social , Señales (Psicología) , Adolescente
4.
J Am Chem Soc ; 145(31): 17220-17231, 2023 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-37492900

RESUMEN

In electrochemical ethanol oxidation reactions (EOR) catalyzed by Pt metal nanoparticles through a C2 route, the dissociation of the C-C bond in the ethanol molecule can be a limiting factor. Complete EOR processes producing CO2 were always exemplified by the oxidative dehydrogenation of C1 intermediates, a reaction route with less energy utilization efficiency. Here, we report a Pt3Ga/C electrocatalyst with a uniform distribution of Ga over the nanoparticle surface for EOR that produces CO2 at medium potentials (>0.3 V vs SCE) efficiently through direct and sustainable oxidation of C2 intermediate species, i.e., acetaldehyde. We demonstrate the excellent performance of the Pt3Ga-200/C catalyst by using electrochemical in situ Fourier transform infrared reflection spectroscopy (FTIR) and an isotopic labeling method. The atomic interval structure between Pt and Ga makes the surface of nanoparticles nonensembled, avoiding the formation of poisonous *CHx and *CO species via bridge-type adsorption of ethanol molecules. Meanwhile, the electron redistribution from Ga to Pt diminishes the *O/*OH adsorption and CO poisoning on Pt atoms, exposing more available sites for interaction with the C2 intermediates. Furthermore, the dissociation of H2O into *OH is facilitated by the high hydrophilicity of Ga, which is supported by DFT calculations, promoting the deep oxidation of C2 intermediates. Our work represents an extremely rare EOR process that produces CO2 without observing kinetic limitations under medium potential conditions.

5.
Phys Rev Lett ; 131(14): 141601, 2023 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-37862633

RESUMEN

Using holographic duality, we present an analytically controlled theory of quantum critical points without quasiparticles, at finite disorder and finite charge density. These fixed points are obtained by perturbing a disorder-free quantum critical point with relevant disorder whose operator dimension is perturbatively close to Harris marginal. We analyze these fixed points both using field theoretic arguments, and by solving the bulk equations of motion in holography. We calculate the critical exponents of the IR theory, together with thermoelectric transport coefficients. Our predictions for the critical exponents of the disordered fixed point are consistent with previous work, both in holographic and nonholograpic models.

6.
Clin Exp Hypertens ; 45(1): 2272062, 2023 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-37899350

RESUMEN

BACKGROUND AND PURPOSE: Substitution of Cys674 (C674) in the sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 2 (SERCA2) causes SERCA2 dysfunction which leads to activated inositol requiring enzyme 1 alpha (IRE1α) and spliced X-box binding protein 1 (XBP1s) pathway accelerating cell proliferation of pulmonary artery smooth muscle cells (PASMCs) followed by significant pulmonary vascular remodeling resembling human pulmonary hypertension. Based on this knowledge, we intend to investigate other potential mechanisms involved in SERCA2 dysfunction-induced pulmonary vascular remodeling. EXPERIMENTAL APPROACH: Heterozygous SERCA2 C674S knock-in (SKI) mice of which half of cysteine in 674 was substituted by serine to mimic the partial irreversible oxidation of C674 were used. The lungs of SKI mice and their littermate wild-type mice were collected for PASMC culture, protein expression, and pulmonary vascular remodeling analysis. RESULTS: SERCA2 dysfunction increased intracellular Ca2+ levels, which activated Ca2+-dependent calcineurin (CaN) and promoted the nuclear translocation and protein expression of the nuclear factor of activated T-lymphocytes 4 (NFAT4) in an IRE1α/XBP1s pathway-independent manner. In SKI PASMCs, the scavenge of intracellular Ca2+ by BAPTA-AM or inhibition of CaN by cyclosporin A can prevent PASMC phenotypic transition. CDN1163, a SERCA2 agonist, suppressed the activation of CaN/NFAT4 and IRE1α/XBP1s pathways, reversed the protein expression of PASMC phenotypic transition markers and cell cycle-related proteins, and inhibited cell proliferation and migration when given to SKI PASMCs. Furthermore, CDN1163 ameliorated pulmonary vascular remodeling in SKI mice. CONCLUSIONS AND IMPLICATIONS: SERCA2 dysfunction promotes PASMC phenotypic transition and pulmonary vascular remodeling by multiple mechanisms, which could be improved by SERCA2 agonist CDN1163.


'What is already known' l The dysfunction of SERCA2 promotes PASMC hyperproliferation and pulmonary vascular remodeling through activation of the IRE1α/XBP1s pathway.'What this study adds' l The dysfunction of SERCA2 activates the Ca2+-dependent CaN-mediated NFAT4 pathway to promote the PASMC phenotypic transition.l Revitalization of SERCA2 suppresses PASMC phenotypic transition and pulmonary vascular remodeling caused by SERCA2 dysfunction.'Clinical significance' l SERCA2 dysfunction-induced pulmonary vascular remodeling involves more than one mechanism, implicating that more drugable targets are to be discovered.l SERCA2 is a potential therapeutic target for preventing pulmonary vascular remodeling.


Asunto(s)
Hipertensión Pulmonar , Hipertensión Arterial Pulmonar , Ratones , Humanos , Animales , Arteria Pulmonar , Endorribonucleasas/metabolismo , Remodelación Vascular , Proteínas Serina-Treonina Quinasas/metabolismo , Hipertensión Arterial Pulmonar/metabolismo , Proliferación Celular , Miocitos del Músculo Liso/metabolismo , Células Cultivadas
7.
Paediatr Perinat Epidemiol ; 36(3): 390-398, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-34431114

RESUMEN

BACKGROUND: For initial respiratory management, continuous positive airway pressure (CPAP) is increasingly used for preterm infants, especially for gestational age less than 32 weeks. However, neonatologists are concerned about the potential risks of CPAP support failure. OBJECTIVES: To examine the association between different initial respiratory support modalities and the outcomes of preterm infants at <32 weeks of gestation across multiple neonatal intensive care units (NICU) in China. METHODS: This study was carried out over a period of 12 months in 2018. Unadjusted relative risks (RR) for demographic and clinical characteristics were calculated for CPAP failure and CPAP success in the total cohort using log-linear model based on generalised estimating equations for clustered observations. RESULTS: Among 1560 preterm infants delivered at <32 weeks, the incidence of CPAP failure was 10.3%. After adjustment for demographic and clinical factors, the relative risk of mortality (RR 7.54, 95% CI 5.56, 10.44), pneumothorax (RR 9.85, 95% CI 2.89, 61.53), pulmonary haemorrhage (RR 7.78, 95% CI 4.51, 14.64) and BPD (RR 3.65, 95% CI 3.65, 4.51) were considerably higher for infants in the CPAP failure group than those in the CPAP-S group. However, the risk of poor outcomes in CPAP failure infants was similar to that of those in the initial mechanical ventilation (MV) group. CONCLUSIONS: Continuous positive airway pressure failure was associated with an increased risk of mortality and major morbidities, including BPD, pulmonary haemorrhage and pneumothorax, and was comparable to the risk associated with initial MV.


Asunto(s)
Neumotórax , Síndrome de Dificultad Respiratoria del Recién Nacido , Presión de las Vías Aéreas Positiva Contínua/efectos adversos , Femenino , Humanos , Lactante , Recién Nacido , Recien Nacido Prematuro , Neumotórax/etiología , Embarazo , Síndrome de Dificultad Respiratoria del Recién Nacido/complicaciones , Síndrome de Dificultad Respiratoria del Recién Nacido/epidemiología , Síndrome de Dificultad Respiratoria del Recién Nacido/terapia , Estudios Retrospectivos
8.
Reprod Biol Endocrinol ; 19(1): 187, 2021 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-34906165

RESUMEN

BACKGROUND: Recurrent implantation failure (RIF) is a major limitation of assisted reproductive technology, which is associated with impaired endometrial receptivity. Although N6-methyladenosine (m6A) has been demonstrated to be involved in various biological processes, its potential role in the endometrium of women with RIF has been poorly studied. METHODS: Global m6A levels and major m6A methyltransferases/demethylases mRNA levels in mid-secretory endometrium from normal and RIF women were examined by colorimetric m6A quantification strategy and quantitative real-time PCR, respectively. The effects of METTL3-mediated m6A modification on embryo attachment were evaluated by an vitro model of a confluent monolayer of Ishikawa cells co-cultured with BeWo spheroids, and the expression levels of homeo box A10 (HOXA10, a well-characterized marker of endometrial receptivity) and its downstream targets were evaluated by quantitative real-time PCR and Western blotting in METTL3-overexpressing Ishikawa cells. The molecular mechanism for METTL3 regulating HOXA10 expression was determined by methylated RNA immunoprecipitation assay and transcription inhibition assay. RESULTS: Global m6A methylation and METTL3 expression were significantly increased in the endometrial tissues from women with RIF compared with the controls. Overexpression of METTL3 in Ishikawa cells significantly decreased the ration of BeWo spheroid attachment, and inhibited HOXA10 expression with downstream decreased ß3-integrin and increased empty spiracles homeobox 2 expression. METTL3 catalyzed the m6A methylation of HOXA10 mRNA and contributed to its decay with shortened half-life. Enforced expression of HOXA10 in Ishikawa cells effectively rescued the impairment of METTL3 on the embryo attachment in vitro. CONCLUSION: Increased METTL3-mediated m6A modification represents an adverse impact on embryo implantation by inhibiting HOXA10 expression, contributing to the pathogenesis of RIF.


Asunto(s)
Implantación del Embrión/genética , Endometrio/metabolismo , Proteínas Homeobox A10/metabolismo , Infertilidad Femenina/metabolismo , Metiltransferasas/metabolismo , Adulto , Línea Celular Tumoral , Metilación de ADN , Femenino , Proteínas Homeobox A10/genética , Humanos , Infertilidad Femenina/genética , Metiltransferasas/genética
9.
Am J Hum Biol ; 33(2): e23459, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-32643228

RESUMEN

OBJECTIVES: In this study, we measured the hematologic and spirometric parameters of native Tajik and Kyrgyz highlanders in the Pamir Mountains to investigate adaptations to high altitude stressors. METHODS: Hematological parameters including arterial oxygen saturation (SaO2 ), red blood cell (RBC) counts, and hemoglobin (Hb) concentration were measured on Sarikoli Tajik (n = 80; 3100 m), Wakhi Tajik (n = 48; 3500 m), and Kyrgyz (n = 64; 3250 m) in comparison to lowland Uyghurs (n = 50; 1300 m). Spirometric parameters including forced vital capacity (FVC), the first second of forced expiration (FEV1), and forced expiratory flow between 25% and 75% (FEF25-75) were measured. We also reported mountain sickness symptoms in these highlanders and conducted a multivariate regression analysis to analyze the association between these symptoms and the measured parameters. RESULTS: SaO2 of Sarikoli Tajik, Wakhi Tajik, and Kyrgyz (91%-93.5%) are significantly lower than lowland Uyghurs, yet are comparable to other native highlanders at a similar altitude. RBC counts and Hb concentrations of all three highland populations are significantly increased compared to Uyghurs. FVC is lower in Sarikoli Tajik, Wakhi Tajik, and Kyrgyz (male: 3.48-3.86 L, female: 2.47-2.78 L) compared to Uyghurs. Combined with normal FEV1, elevated FEV1/FVC ratio, and FEF25-75, the spirometric patterns of these highlanders indicate restrictive lung disease. A high prevalence of mountain sickness symptoms such as headache and nausea was found in all three highland populations, and are attributed to low FVC and aging by regression analysis. CONCLUSION: Tajik and Kyrgyz highlanders showed adaptation in SaO2 , RBC, and Hb level, but poor performance in spirometry, which causes mountain sickness.


Asunto(s)
Mal de Altura/epidemiología , Análisis Químico de la Sangre/estadística & datos numéricos , Etnicidad/estadística & datos numéricos , Pruebas de Función Respiratoria/estadística & datos numéricos , Adolescente , Adulto , Anciano , China/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven
10.
Sensors (Basel) ; 21(2)2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33435533

RESUMEN

It is a challenge to transmit and store the massive visual data generated in the Visual Internet of Things (VIoT), so the compression of the visual data is of great significance to VIoT. Compressing bit-depth of images is very cost-effective to reduce the large volume of visual data. However, compressing the bit-depth will introduce false contour, and color distortion would occur in the reconstructed image. False contour and color distortion suppression become critical issues of the bit-depth enhancement in VIoT. To solve these problems, a Bit-depth Enhancement method with AUTO-encoder-like structure (BE-AUTO) is proposed in this paper. Based on the convolution-combined-with-deconvolution codec and global skip of BE-AUTO, this method can effectively suppress false contour and color distortion, thus achieving the state-of-the-art objective metric and visual quality in the reconstructed images, making it more suitable for bit-depth enhancement in VIoT.

11.
Sensors (Basel) ; 22(1)2021 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-35009793

RESUMEN

With the rise of deep learning, using deep learning to segment lesions and assist in diagnosis has become an effective means to promote clinical medical analysis. However, the partial volume effect of organ tissues leads to unclear and blurred edges of ROI in medical images, making it challenging to achieve high-accuracy segmentation of lesions or organs. In this paper, we assume that the distance map obtained by performing distance transformation on the ROI edge can be used as a weight map to make the network pay more attention to the learning of the ROI edge region. To this end, we design a novel framework to flexibly embed the distance map into the two-stage network to improve left atrium MRI segmentation performance. Furthermore, a series of distance map generation methods are proposed and studied to reasonably explore how to express the weight of assisting network learning. We conduct thorough experiments to verify the effectiveness of the proposed segmentation framework, and experimental results demonstrate that our hypothesis is feasible.


Asunto(s)
Fenómenos Biológicos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética
12.
Soft Matter ; 16(15): 3649-3656, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-32202268

RESUMEN

The deposition of colloidal particles can cause particulate fouling on solid walls and the formation of clogs during the transport of colloidal suspensions in microchannels. The particle deposition rate grows over time and blocks the microchannels eventually. The process of particle deposition is affected by various physicochemical parameters. In this paper, we investigate the effect of temperature gradient on the particle deposition of a pressure-driven suspension flow in a microchannel. We designed a microfluidic device which can allow direct observation of the real-time process of particle deposition with single-particle resolution along the direction of applied temperature gradient. The experimental results show that particle deposition rate is decreased by increasing the applied temperature gradients. Based on the framework of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, we then derive a mass transport model to describe the particle deposition under different temperature gradients. The model shows that the observed reduction of particle deposition rate with temperature gradient is due to the collective effect of the temperature gradient and the bulk solution temperature in the two steps of the particle deposition process, including the particle transport and the particle attachment. Our work illustrates the critical effects of temperature gradients on the particle deposition in microchannels, and is expected to provide a better understanding of thermally driven particulate fouling and clogging in microfluidic devices.

13.
BMC Pediatr ; 20(1): 321, 2020 06 29.
Artículo en Inglés | MEDLINE | ID: mdl-32600275

RESUMEN

BACKGROUND: The objective of this prospective, multicentre, observational cohort study was to evaluate the association between admission hypothermia and neonatal outcomes in very low-birth weight (VLBW) infants in multiple neonatal intensive care units (NICUs) in China. METHODS: Since January 1, 2018, a neonatal homogeneous cooperative research platform-Shandong Neonatal Network (SNN) has been established. The platform collects clinical data in a prospective manner on preterm infants with birth weights (BWs) < 1500 g and gestational ages (GAs) < 34 weeks born in 28 NICUs in Shandong Province. These infants were divided into normothermia, mild or moderate/severe hypothermia groups according to the World Health Organization (WHO) classifications of hypothermia. Associations between outcomes and hypothermia were tested in a bivariate analysis, followed by a logistic regression analysis. RESULTS: A total of 1247 VLBW infants were included in this analysis, of which 1100 infants (88.2%) were included in the hypothermia group, 554 infants (44.4%) in the mild hypothermia group and 546 infants (43.8%) in the moderate/severe hypothermia group. Small for gestational age (SGA), caesarean section, a low Apgar score at 5 min and intubation in the delivery room (DR) were related to admission hypothermia (AH). Mortality was the lowest when their admission temperature was 36.5 ~ 37.5 °C, and after adjustment for maternal and infant characteristics, mortality was significantly associated with AH. Compared with infants with normothermia (36.5 ~ 37.5 °C), the adjusted ORs of all deaths increased to 4.148 (95% CI 1.505-11.437) and 1.806 (95% CI 0.651-5.009) for infants with moderate/severe hypothermia and mild hypothermia, respectively. AH was also associated with a high likelihood of respiratory distress syndrome (RDS), intraventricular haemorrhage (IVH), and late-onset neonatal sepsis (LOS). CONCLUSIONS: AH is still very high in VLBW infants in NICUs in China. SGA, caesarean section, a low Apgar score at 5 min and intubation in the DR were associated with increased odds of hypothermia. Moderate/severe hypothermia was associated with mortality and poor outcomes, such as RDS, IVH, LOS.


Asunto(s)
Hipotermia , Cesárea , China/epidemiología , Femenino , Humanos , Hipotermia/epidemiología , Hipotermia/etiología , Lactante , Recién Nacido , Recien Nacido Prematuro , Recién Nacido de muy Bajo Peso , Unidades de Cuidado Intensivo Neonatal , Embarazo , Estudios Prospectivos
14.
J Gastroenterol Hepatol ; 34(12): 2144-2151, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31265738

RESUMEN

BACKGROUND AND AIM: Although various endoscopic technologies have been developed to increase the visual diagnostic accuracy of colorectal precancerosis and early carcinoma, the biopsy-dependent pathology still remains the golden standard. During routine endoscopy, real-time optical histological diagnosis is desired. Without fluorescent label, multiphoton microscopy (MPM) imaging directly reveals live cellular morphology and tissue microenvironment based on intrinsic two-photon excited fluorescence and second harmonic generation signals. Its high-imaging resolution and performance are comparable with the histopathology. We thus aimed to initially investigate the original features of colorectal diseases under MPM and evaluate its potential for real-time diagnosis. METHODS: Experimental and diagnostic cohorts were designed. Multiphoton images of 40 ex vivo fresh tissues confirmed pathologically of colorectal normal tissues, hyperplastic polyps, adenomas, and adenocarcinomas were collected. Features were recorded to establish diagnostic standards with MPM. For the second cohort with 92 fresh tissues, we distinguished the various colorectal diseases with conclusive MPM features. RESULTS: Through the investigation, the colorectal diseases were presented differences in the crypt opening, gland structure, epithelial cells, and collagen fibers. With the typical features, we preliminarily tested the diagnostic efficiency and found that its sensitivity for distinguishing normal, hyperplastic polyps, adenoma and adenocarcinoma was 88.89%, 76.47%, 83.33%, and 97.92%, while the specificity was 99.32%, 94.00%, 94.92%, and 94.12%, respectively. CONCLUSION: The real-time multiphoton microscopic imaging can be effective to identify the colorectal lesions with high resolution. Via integrating with the endoscopes in the future, it could promote precise optical diagnosis in clinics.


Asunto(s)
Neoplasias Colorrectales/diagnóstico , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , Adenocarcinoma/diagnóstico , Adenocarcinoma/patología , Adenoma/diagnóstico , Adenoma/patología , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Colorrectales/patología , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Sensibilidad y Especificidad , Método Simple Ciego , Manejo de Especímenes/métodos
15.
Chemistry ; 24(10): 2396-2402, 2018 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-29266447

RESUMEN

Mg(OH)2 - and Mg(OH)2 -containing materials can provide excellent performance as supports for AuPd nanoparticles for the oxidation of glycerol in the absence of base, which is considered to be a result of additional basic sites on the surface of the support. However, its influence on the reaction solution is not generally discussed. In this paper, we examine the relationship between the basic Mg(OH)2 support and AuPd nanoparticles in detail using four types of catalyst. For these reactions, the physical interaction between Mg(OH)2 and AuPd was adjusted. It was found that the activity of the AuPd nanoparticles increased with the amount of Mg(OH)2 added under base-free conditions, regardless of its interaction with the noble metals. In order to investigate how Mg(OH)2 affected the glycerol oxidation, detailed information about the performance of AuPd/Mg(OH)2 , physically mixed (AuPd/C+Mg(OH)2 ) and (AuPd/C+NaHCO3 ) was obtained and compared. Furthermore, NaOH and Mg(OH)2 were added during the reaction using AuPd/C. All these results indicate that the distinctive and outstanding performance of Mg(OH)2 supported catalysts in base-free condition is in fact directly related to its ability to affect the pH during the reaction and as such, assists with the initial activation of the primary alcohol, which is considered to be the rate determining step in the reaction.

16.
Lasers Med Sci ; 33(4): 871-882, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29411176

RESUMEN

Gastric cancer is one of the most common malignancies worldwide. The accurate diagnosis of tumor invasion depth is critical for therapeutic strategy and prognosis. Without fluorescent labelling, multiphoton microscopy (MPM) imaging could directly reveal tissue architecture based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). In this study, we aimed to explore the feasibility of MPM imaging to assess the gastric tumor morphology and infiltration. Unstained slides of 18 fresh gastric tissues with different T staging were examined by multiphoton microscopy. Morphological and quantitative analyses were both conducted. The nuclear area was defined as the area of nuclear boundary. Collagen content was defined as the ratio of SHG pixels to all pixels. Gastric normal and tumor tissues under different T stages visually presented with cellular and subcellular features on fluorescent imaging. The nuclear areas of normal and cancerous cells were 32.01 ± 2.89 and 58.41 ± 6.06 µm2 (P < 0.001), respectively. Collagen content was quantified as 0.087 ± 0.012 in normal mucosa but 0.020 ± 0.007 in cancerous mucosa (P < 0.001). All results were in accord with the paired H&E-stained slides. Our findings suggested the convincing potential of MPM for judging T staging of gastric cancer. Without staining intervention, TPEF and SHG of MPM imaging could objectively and quantitatively indicate the subcellular and molecular changes during carcinogenesis. With the advancement of deep penetration, self-focus imaging and three-dimensional (3D) visualization, label-free MPM imaging compacted with endoscopy could be further introduced to realize the real-time in vivo assessment of tumor invasion clinically.


Asunto(s)
Neoplasias Gástricas/diagnóstico por imagen , Anciano , Femenino , Mucosa Gástrica/diagnóstico por imagen , Mucosa Gástrica/patología , Humanos , Masculino , Microscopía de Fluorescencia por Excitación Multifotónica , Persona de Mediana Edad , Estadificación de Neoplasias , Neoplasias Gástricas/patología
17.
J Pharmacol Sci ; 132(1): 31-40, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27094368

RESUMEN

SIRT6 is a member of the sirtuin family of class III histone deacetylases. It plays important roles in regulating genomic stability, metabolism, stress response and aging. Our previous study has revealed that SIRT6 attenuates myocardial hypertrophy by inhibiting NF-κB activation, but the related molecular mechanisms remain to be clarified. In the present study, we showed that the p300 acetylase was involved in the protective effect of SIRT6 against phenylephrine (PE)-induced cardiomyocyte hypertrophy. In cultured neonatal rat cardiomyocytes, the expression and activity of SIRT6 declined following PE treatment, while the protein level of p300 was upregulated. PE triggered significant hypertrophic responses as manifested by increase in cellular surface area and expression of hypertrophy marker genes, which could be blocked by SIRT6 overexpression. Mechanistically, SIRT6 reduced p300 protein expression via promoting its degradation, which could be attributed to the suppression of PI3K/Akt signaling. The downregulation of p300 protein level by SIRT6 subsequently decreased the acetylation and transcriptional activity of NF-κB p65 subunit. These findings help to further understand mechanisms underlying the anti-hypertrophic role of SIRT6 and suggest the potential of SIRT6 as a therapeutic target for cardiac hypertrophy.


Asunto(s)
Cardiomegalia/metabolismo , Proteína p300 Asociada a E1A/metabolismo , Miocitos Cardíacos/metabolismo , Sirtuinas/metabolismo , Animales , Cardiomegalia/inducido químicamente , Células Cultivadas , Proteína p300 Asociada a E1A/genética , FN-kappa B/genética , Fenilefrina , ARN Interferente Pequeño/genética , Ratas Sprague-Dawley , Sirtuinas/genética
18.
J Mol Cell Cardiol ; 79: 92-103, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25446184

RESUMEN

BACKGROUND: α-Enolase is a glycolytic enzyme with "second jobs" beyond its catalytic activity. However, its possible contribution to cardiac dysfunction remains to be determined. The present study aimed to investigate the role of α-enolase in doxorubicin (Dox)-induced cardiomyopathy as well as the underlying mechanisms. EXPERIMENTAL APPROACHES: The expression of α-enolase was detected in rat hearts and primary cultured rat cardiomyocytes with or without Dox administration. An adenovirus carrying short-hairpin interfering RNA targeting α-enolase was constructed and transduced specifically into the heart by intramyocardial injection. Heart function, cell apoptosis and mitochondrial function were measured following Dox administration. In addition, by using gain- and loss-of-function approaches to regulate α-enolase expression in primary cultured rat cardiomyocytes, we investigated the role of endogenous, wide type and catalytically inactive mutant α-enolase in cardiomyocyte apoptosis and ATP generation. Furthermore, the involvement of α-enolase in AMPK phosphorylation was also studied. KEY RESULTS: The mRNA and protein expression of cardiac α-enolase was significantly upregulated by Dox. Genetic silencing of α-enolase in rat hearts and cultured cardiomyocytes attenuated Dox-induced apoptosis and mitochondrial dysfunction. In contrast, overexpression of wide-type or catalytically inactive α-enolase in cardiomyocytes mimicked the detrimental role of Dox in inducing apoptosis and ATP reduction. AMPK dephosphorylation was further demonstrated to be involved in the proapoptotic and ATP-depriving effects of α-enolase. CONCLUSION: Our findings provided the evidence that α-enolase has a catalytically independent role in inducing cardiomyocyte apoptosis and mitochondrial dysfunction, which could be at least partially contributed to the inhibition of AMPK phosphorylation.


Asunto(s)
Apoptosis/efectos de los fármacos , Doxorrubicina/farmacología , Mitocondrias/metabolismo , Miocitos Cardíacos/enzimología , Fosfopiruvato Hidratasa/metabolismo , Adenosina Trifosfato/metabolismo , Adenoviridae/metabolismo , Adenilato Quinasa/metabolismo , Animales , Biocatálisis/efectos de los fármacos , Respiración de la Célula/efectos de los fármacos , Células Cultivadas , Regulación hacia Abajo/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Silenciador del Gen/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Miocardio/enzimología , Miocitos Cardíacos/efectos de los fármacos , Fosforilación/efectos de los fármacos , Ratas Sprague-Dawley , Regulación hacia Arriba/efectos de los fármacos
19.
Arch Biochem Biophys ; 565: 76-88, 2015 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-25436917

RESUMEN

Adipose triglyceride lipase (ATGL), the rate-limiting enzyme of triglyceride (TG) hydrolysis, plays an important role in TG metabolism. ATGL knockout mice suffer from TG accumulation and die from heart failure. However, the mechanisms underlying cardiac hypertrophy caused by ATGL dysfunction remain unknown. In this study, we found that ATGL expression declined in pressure overload-induced cardiac hypertrophy in vivo and phenylephrine (PE)-induced cardiomyocyte hypertrophy in vitro. ATGL knockdown led to cardiomyocyte hypertrophy, while ATGL overexpression prevented PE-induced hypertrophy. In addition, ATGL downregulation increased but ATGL overexpression reduced the contents of ceramide, which has been proved to be closely associated with cardiac hypertrophy. Moreover, the accumulation of ceramide was due to elevation of free fatty acids in ATGL-knockdown cardiomyocytes, which could be explained by the reduced activity of peroxisome proliferator-activated receptor (PPAR) α leading to imbalance of fatty acid uptake and oxidation. These observations suggest that downregulation of ATGL causes the decreased PPARα activity which results in the imbalance of FA uptake and oxidation, elevating intracellular FFA contents to promote the accumulation of ceramides, and finally inducing cardiac hypertrophy. Upregulation of ATGL could be a strategy for ameliorating lipotoxic damage in cardiac hypertrophy.


Asunto(s)
Cardiomegalia/enzimología , Ceramidas/metabolismo , Regulación Enzimológica de la Expresión Génica , Lipasa/biosíntesis , Miocitos Cardíacos/enzimología , Animales , Cardiomegalia/genética , Cardiomegalia/patología , Ceramidas/genética , Técnicas de Silenciamiento del Gen , Lipasa/genética , Masculino , Ratones , Miocitos Cardíacos/patología , Oxidación-Reducción , PPAR alfa/genética , PPAR alfa/metabolismo , Ratas , Ratas Sprague-Dawley
20.
Biomed Eng Online ; 14: 57, 2015 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-26087652

RESUMEN

BACKGROUND: Fuzzy connectedness method has shown its effectiveness for fuzzy object extraction in recent years. However, two problems may occur when applying it to hepatic vessel segmentation task. One is the excessive computational cost, and the other is the difficulty of choosing a proper threshold value for final segmentation. METHODS: In this paper, an accelerated strategy based on a lookup table was presented first which can reduce the connectivity scene calculation time and achieve a speed-up factor of above 2. When the computing of the fuzzy connectedness relations is finished, a threshold is needed to generate the final result. Currently the threshold is preset by users. Since different thresholds may produce different outcomes, how to determine a proper threshold is crucial. According to our analysis of the hepatic vessel structure, a watershed-like method was used to find the optimal threshold. Meanwhile, by using Ostu algorithm to calculate the parameters for affinity relations and assigning the seed with the mean value, it is able to reduce the influence on the segmentation result caused by the location of the seed and enhance the robustness of fuzzy connectedness method. RESULTS: Experiments based on four different datasets demonstrate the efficiency of the lookup table strategy. These experiments also show that an adaptive threshold found by watershed-like method can always generate correct segmentation results of hepatic vessels. Comparing to a refined region-growing algorithm that has been widely used for hepatic vessel segmentation, fuzzy connectedness method has advantages in detecting vascular edge and generating more than one vessel system through the weak connectivity of the vessel ends. CONCLUSIONS: An improved algorithm based on fuzzy connectedness method is proposed. This algorithm has improved the performance of fuzzy connectedness method in hepatic vessel segmentation.


Asunto(s)
Algoritmos , Lógica Difusa , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/estadística & datos numéricos , Hígado/diagnóstico por imagen , Tomografía Computarizada por Rayos X/estadística & datos numéricos , Conjuntos de Datos como Asunto/estadística & datos numéricos , Humanos , Hígado/irrigación sanguínea , Tomografía Computarizada por Rayos X/instrumentación
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