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1.
Proc Natl Acad Sci U S A ; 118(14)2021 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-33785600

RESUMO

The contraction of heart cells is controlled by the intermolecular signaling between L-type Ca2+ channels (LCCs) and ryanodine receptors (RyRs), and the nanodistance between them depends on the interaction between junctophilin-2 (JPH2) in the sarcoplasmic reticulum (SR) and caveolin-3 (CAV3) in the transversal tubule (TT). In heart failure, decreased expression of JPH2 compromises LCC-RyR communication leading to deficient blood-pumping power. In the present study, we found that JPH2 and CAV3 transcription was concurrently regulated by serum response factor (SRF) and myocardin. In cardiomyocytes from torpid ground squirrels, compared with those from euthermic counterparts, myocardin expression was up-regulated, which boosted both JPH2 and CAV3 expression. Transmission electron microscopic imaging showed that the physical coupling between TTs and SRs was tightened during hibernation and after myocardin overexpression. Confocal Ca2+ imaging under the whole-cell patch clamp condition revealed that these changes enhanced the efficiency of LCC-RyR intermolecular signaling and fully compensated the adaptive down-regulation of LCCs, maintaining the power of heart contraction while avoiding the risk of calcium overload during hibernation. Our finding not only revealed an essential molecular mechanism underlying the survival of hibernating mammals, but also demonstrated a "reverse model of heart failure" at the molecular level, suggesting a strategy for treating heart diseases.


Assuntos
Sinalização do Cálcio , Hibernação , Miócitos Cardíacos/metabolismo , Animais , Caveolinas/genética , Caveolinas/metabolismo , Células Cultivadas , Acoplamento Excitação-Contração , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Nucleares/sangue , Proteínas Nucleares/metabolismo , Sciuridae , Transativadores/sangue , Transativadores/metabolismo
2.
Bioorg Med Chem Lett ; 30(1): 126662, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31784322

RESUMO

Starting from easy accessible pyrazoletetrahydropyran acetals, a series of new pyrazolone spirocyclohexadienone derivatives were synthesized and assayed for antitumor activity. Compound 10s was identified to possess good antitumor activity. It could induce MDA-MB-231 cancer cell apoptosis in a concentration dependent manner and arrest the cell cycle progression mainly at the G1 phase.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias/tratamento farmacológico , Pirazolonas/uso terapêutico , Antineoplásicos/farmacologia , Humanos , Estrutura Molecular , Pirazolonas/farmacologia , Relação Estrutura-Atividade
3.
Stem Cells ; 33(2): 615-21, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25263397

RESUMO

Mesenchymal stem cells (MSCs) are multipotential stem cells residing in the bone marrow. Several studies have shown that mechanical stimulation modulates MSC differentiation through mobilization of second messengers, but the mechanism of mechanotransduction remains poorly understood. In this study, using fluorescence and laser confocal microcopy as well as patch-clamp techniques, we identified the transient receptor potential melastatin type 7 (TRPM7) channel as the key channel involved in mechanotransduction in bone marrow MSCs. TRPM7 knockdown completely abolished the pressure-induced cytosolic Ca(2+) increase and pressure-induced osteogenesis. TRPM7 directly sensed membrane tension, independent of the cytoplasm and the integrity of cytoskeleton. Ca(2+) influx through TRPM7 further triggered Ca(2+) release from the inositol trisphosphate receptor type 2 on the endoplasmic reticulum and promoted NFATc1 nuclear localization and osteogenesis. These results identified a central role of TRPM7 in MSC mechanical stimulation-induced osteogenesis.


Assuntos
Células da Medula Óssea/metabolismo , Mecanotransdução Celular/fisiologia , Células-Tronco Mesenquimais/metabolismo , Osteogênese , Pressão , Proteínas Serina-Treonina Quinases/metabolismo , Canais de Cátion TRPM/metabolismo , Células da Medula Óssea/citologia , Células Cultivadas , Humanos , Células-Tronco Mesenquimais/citologia
4.
Circ Res ; 112(4): 601-5, 2013 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-23307820

RESUMO

RATIONALE: During the transition from compensated hypertrophy to heart failure, the signaling between L-type Ca(2+) channels in the cell membrane/T-tubules and ryanodine receptors in the sarcoplasmic reticulum becomes defective, partially because of the decreased expression of a T-tubule-sarcoplasmic reticulum anchoring protein, junctophilin-2. MicroRNA (miR)-24, a junctophilin-2 suppressing miR, is upregulated in hypertrophied and failing cardiomyocytes. OBJECTIVE: To test whether miR-24 suppression can protect the structural and functional integrity of L-type Ca(2+) channel-ryanodine receptor signaling in hypertrophied cardiomyocytes. METHODS AND RESULTS: In vivo silencing of miR-24 by a specific antagomir in an aorta-constricted mouse model effectively prevented the degradation of heart contraction, but not ventricular hypertrophy. Electrophysiology and confocal imaging studies showed that antagomir treatment prevented the decreases in L-type Ca(2+) channel-ryanodine receptor signaling fidelity/efficiency and whole-cell Ca(2+) transients. Further studies showed that antagomir treatment stabilized junctophilin-2 expression and protected the ultrastructure of T-tubule-sarcoplasmic reticulum junctions from disruption. CONCLUSIONS: MiR-24 suppression prevented the transition from compensated hypertrophy to decompensated hypertrophy, providing a potential strategy for early treatment against heart failure.


Assuntos
Sinalização do Cálcio/efeitos dos fármacos , Acoplamento Excitação-Contração/efeitos dos fármacos , Insuficiência Cardíaca/prevenção & controle , Hipertrofia Ventricular Esquerda/tratamento farmacológico , MicroRNAs/antagonistas & inibidores , Miócitos Cardíacos/efeitos dos fármacos , Oligonucleotídeos Antissenso/uso terapêutico , Animais , Estenose Aórtica Subvalvar/complicações , Canais de Cálcio Tipo L/fisiologia , Sinalização do Cálcio/fisiologia , Progressão da Doença , Avaliação Pré-Clínica de Medicamentos , Regulação da Expressão Gênica , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/metabolismo , Hipertrofia Ventricular Esquerda/complicações , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Proteínas de Membrana/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , MicroRNAs/fisiologia , Modelos Cardiovasculares , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/ultraestrutura , Oligonucleotídeos Antissenso/farmacologia , Canal de Liberação de Cálcio do Receptor de Rianodina/fisiologia , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/fisiologia , Retículo Sarcoplasmático/ultraestrutura
5.
Circ Res ; 111(7): 837-41, 2012 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-22891046

RESUMO

RATIONALE: Failing cardiomyocytes exhibit decreased efficiency of excitation-contraction (E-C) coupling. The downregulation of junctophilin-2 (JP2), a protein anchoring the sarcoplasmic reticulum to T-tubules, has been identified as a major mechanism underlying the defective E-C coupling. However, the regulatory mechanism of JP2 remains unknown. OBJECTIVE: To determine whether microRNAs regulate JP2 expression. METHODS AND RESULTS: Bioinformatic analysis predicted 2 potential binding sites of miR-24 in the 3'-untranslated regions of JP2 mRNA. Luciferase assays confirmed that miR-24 suppressed JP2 expression by binding to either of these sites. In the aortic stenosis model, miR-24 was upregulated in failing cardiomyocytes. Adenovirus-directed overexpression of miR-24 in cardiomyocytes decreased JP2 expression and reduced Ca(2+) transient amplitude and E-C coupling gain. CONCLUSIONS: MiR-24-mediated suppression of JP2 expression provides a novel molecular mechanism for E-C coupling regulation in heart cells and suggests a new target against heart failure.


Assuntos
Estenose da Valva Aórtica/metabolismo , Insuficiência Cardíaca/metabolismo , Proteínas de Membrana/metabolismo , MicroRNAs/metabolismo , Miócitos Cardíacos/metabolismo , Regulação para Cima , Animais , Estenose da Valva Aórtica/patologia , Cálcio/metabolismo , Células Cultivadas , Biologia Computacional , Acoplamento Excitação-Contração/fisiologia , Insuficiência Cardíaca/patologia , Proteínas de Membrana/genética , MicroRNAs/genética , Modelos Animais , Miócitos Cardíacos/patologia , RNA Mensageiro/metabolismo , Ratos , Retículo Sarcoplasmático/fisiologia
6.
Int J Cancer ; 131(2): 488-96, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-21866550

RESUMO

XPA, a zinc-finger DNA-binding protein, play an important role in both global genome and transcription-coupled repair pathways. XPA -4G>A polymorphism was identified in the 5' noncoding region, located four nucleotides upstream of the ATG start codon. Previous studies have shown that this polymorphism may affect mRNA tertiary structure and stability and play a role in susceptibility to cancer. However, the results remained controversial. To derive a more precise estimation of association between this polymorphism and risk of different types of cancer, we performed a meta-analysis based on 36 case-control or case-cohort studies, including a total of 11,700 cases and 15,033 controls. We used odds ratios with 95% confidence intervals to assess the strength of the association. Overall, no significantly elevated cancer risk was found in all genetic models when eligible studies were pooled into the meta-analysis. In the stratified analyses, we found that individuals with A-allele had a higher risk of lung cancer (AA versus GG: OR = 1.25, 95% CI = 1.09-1.43; recessive model: OR = 1.31, 95% CI = 1.16-1.48). When stratified by ethnicity, significantly elevated risks were observed among Asian populations (AA versus GG: OR = 1.31, 95% CI = 1.01-1.70; dominant model: OR = 1.14, 95% CI = 1.00-1.30). This meta-analysis suggests that XPA -4G>A polymorphism is associated with increased lung cancer risk and may be a low-penetrant risk factor in Asian ethnicity for cancer development.


Assuntos
Predisposição Genética para Doença , Neoplasias Pulmonares/genética , Neoplasias/genética , Polimorfismo de Nucleotídeo Único , Proteína de Xeroderma Pigmentoso Grupo A/genética , Povo Asiático/genética , Estudos de Casos e Controles , Variação Genética , Humanos , Neoplasias Pulmonares/etnologia , Neoplasias/etnologia , Razão de Chances
7.
Anal Chem ; 84(7): 3376-81, 2012 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-22413933

RESUMO

We developed novel flow-through surface-enhanced Raman scattering (SERS) platforms using gold nanoparticle (Au-NP) immobilized multihole capillaries for rapid and sensitive vapor detection. The multihole capillaries consisting of thousands of micrometer-sized flow-through channels provide many unique characteristics for vapor detection. Most importantly, its three-dimensional SERS-active micro-/nanostructures make available multilayered assembly of Au-NPs, which greatly increase SERS-active surface area within a focal volume of excitation and collection, thus improving the detection sensitivity. In addition, the multihole capillary's inherent longitudinal channels offer rapid and convenient vapor delivery, yet its micrometer-sized holes increase the interaction between vapor molecules and SERS-active substrate. Experimentally, rapid pyridine vapor detection (within 1 s of exposure) and ultrasensitive 4-nitrophenol vapor detection (at a sub-ppb level) were successfully achieved in open air at room temperature. Such an ultrasensitive SERS platform enabled, for the first time, the investigation of both pyridine and 4-nitrophenol vapor adsorption isotherms at very low concentrations. Type I and type V behaviors of the International Union of Pure and Applied Chemistry isotherm were well observed, respectively.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Análise Espectral Raman/métodos , Nitrofenóis/química , Piridinas/química , Propriedades de Superfície , Volatilização
8.
J Theor Biol ; 309: 29-33, 2012 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-22659040

RESUMO

TH17 is a subset of CD4+T cells. Comparing to common asthma patients, there are more TH17 cells in the respiratory systems of the patients with severe asthma. TH17 cells are mainly adjusted by IL23 to produce IL17A and IL17F, which act on the epithelial cells and cause severe asthma. However, the TH17 function in severe asthma as a driving mechanism of neutrophilic inflammation is not yet fully understood and deserves further study. However, it is very difficult to describe the interactions between TH17 and other cells using mathematics equations due to the high complexity of immunity system. In order to explore the TH17 function in severe asthma, we used BIS (Basic Immune Simulator) platform to simulate TH17 models, and compared DC (Dendritic Cell) models with TH17 models. We studied the interaction between innate immune and adaptive immune cells, which was resulted from TH17 cells. The simulation results for the TH17 models are consistent with clinical data, which suggests that DC-IL23-TH17 axis might be the path of causing severe asthma. Our simulation studies support a role for TH17 in severe asthma, and hence it could be taken as a new target candidate for clinical treatment of severe asthma.


Assuntos
Asma/imunologia , Modelos Imunológicos , Transdução de Sinais/imunologia , Células Th17/imunologia , Simulação por Computador , Humanos , Contagem de Linfócitos
9.
Proc Natl Acad Sci U S A ; 106(42): 18028-33, 2009 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-19815510

RESUMO

As the most prototypical G protein-coupled receptor, beta-adrenergic receptor (betaAR) regulates the pace and strength of heart beating by enhancing and synchronizing L-type channel (LCC) Ca(2+) influx, which in turn elicits greater sarcoplasmic reticulum (SR) Ca(2+) release flux via ryanodine receptors (RyRs). However, whether and how betaAR-protein kinase A (PKA) signaling directly modulates RyR function remains elusive and highly controversial. By using unique single-channel Ca(2+) imaging technology, we measured the response of a single RyR Ca(2+) release unit, in the form of a Ca(2+) spark, to its native trigger, the Ca(2+) sparklet from a single LCC. We found that acute application of the selective betaAR agonist isoproterenol (1 microM, < or = 20 min) increased triggered spark amplitude in an LCC unitary current-independent manner. The increased ratio of Ca(2+) release flux underlying a Ca(2+) spark to SR Ca(2+) content indicated that betaAR stimulation helps to recruit additional RyRs in synchrony. Quantification of sparklet-spark kinetics showed that betaAR stimulation synchronized the stochastic latency and increased the fidelity (i.e., chance of hit) of LCC-RyR intermolecular signaling. The RyR modulation was independent of the increased SR Ca(2+) content. The PKA antagonists Rp-8-CPT-cAMP (100 microM) and H89 (10 microM) both eliminated these effects, indicating that betaAR acutely modulates RyR activation via the PKA pathway. These results demonstrate unequivocally that RyR activation by a single LCC is accelerated and synchronized during betaAR stimulation. This molecular mechanism of sympathetic regulation will permit more fundamental studies of altered betaAR effects in cardiovascular diseases.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Miócitos Cardíacos/metabolismo , Receptores Adrenérgicos beta/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Agonistas Adrenérgicos beta/farmacologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Técnicas In Vitro , Isoproterenol/farmacologia , Microscopia Confocal , Contração Miocárdica/fisiologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Retículo Sarcoplasmático/metabolismo , Transdução de Sinais/fisiologia
10.
Physiol Meas ; 43(10)2022 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-35705072

RESUMO

Objective.Automatic detection of arrhythmia based on electrocardiogram (ECG) plays a critical role in early prevention and diagnosis of cardiovascular diseases. With the increase in widely available digital ECG data and the development of deep learning, multi-class arrhythmia classification based on automatic feature extraction of ECG has become increasingly attractive. However, the majority of studies cannot accept varied-length ECG signals and have limited performance in detecting multi-class arrhythmias.Approach.In this study, we propose a multi-branch signal fusion network (MBSF-Net) for multi-label classification of arrhythmia in 12-lead varied-length ECG. Our model utilizes the complementary power between different structures, which include Inception with depthwise separable convolution (DWS-Inception), spatial pyramid pooling (SPP) Layer, and multi-scale fusion Resnet (MSF-Resnet). The proposed method can extract features from each lead of 12-lead ECG recordings separately and then effectively fuse the features of each lead by integrating multiple convolution kernels with different receptive fields, which can achieve the information of complementation between different angles of the ECG signal. In particular, our model can accept 12-lead ECG signals of arbitrary length.Main results.The experimental results show that our model achieved an overall classification F1 score of 83.8% in the 12-lead ECG data of CPSC-2018. In addition, the F1 score of the MBSF-Net performed best among the MBF-Nets which are removed the SPP layer from MBSF-Net. In comparison with the latest ECG classification algorithms, the proposed model can be applied in varied-length signals and has an excellent performance, which not only can fully retain the integrity of the original signals, but also eliminates the cropping/padding signal beforehand when dealing with varied-length signal database.Significance.MBSF-Net provides an end-to-end multi-label classification model with outperfom performance, which allows detection of disease in varied-length signals without any additional cropping/padding. Moreover, our research is beneficial to the development of computer-aided diagnosis.


Assuntos
Eletrocardiografia , Redes Neurais de Computação , Humanos , Arritmias Cardíacas/diagnóstico , Algoritmos , Diagnóstico por Computador , Processamento de Sinais Assistido por Computador
11.
Anal Chem ; 82(12): 5211-8, 2010 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-20486666

RESUMO

Real-time measurement of specific biomolecular interactions is critical to many areas of biological research. A number of label-free techniques for directly monitoring biomolecular binding have been developed, but it is still challenging to measure the binding kinetics of very small molecules, to detect low concentrations of analyte molecules, or to detect low affinity interactions. In this study, we report the development of a highly sensitive photonic crystal biosensor for label-free, real-time biomolecular binding analysis. We characterize the performance of this biosensor using a standard streptavidin-biotin binding system. Optimization of the surface functionalization methods for streptavidin immobilization on the silica sensing surface is presented, and the specific binding of biotinylated analyte molecules ranging over 3 orders of magnitude in molecular weight, including very small molecules (<250 Da), DNA oligonucleotides, proteins, and antibodies (>150 000 Da), are detected in real time with a high signal-to-noise ratio. Finally, we document the sensor efficiency for low mass adsorption, as well as multilayered molecular interactions. By all important metrics for sensitivity, we anticipate this photonic crystal biosensor will provide new capabilities for highly sensitive measurements of biomolecular binding.


Assuntos
Técnicas Biossensoriais/métodos , Biotina/metabolismo , Estreptavidina/metabolismo , Anticorpos/metabolismo , Sítios de Ligação , Biotinilação , Oligonucleotídeos/metabolismo , Fótons , Ligação Proteica , Proteínas/metabolismo , Sensibilidade e Especificidade
12.
Opt Express ; 18(24): 25081-8, 2010 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-21164854

RESUMO

We theoretically analyze the ability of 3-dimensionally confined optofluidic ring resonators (OFRRs) for detection of a single nanoparticle in water and in air. The OFRR is based on a glass capillary, on which bottle-shaped and bubble-shaped ring resonators can form. The spectral position of the whispering gallery mode in the OFRR shifts when a nanoparticle is attached to the OFRR inner surface. For both ring resonator structures, the electric field at the inner surface can be optimized by choosing the right wall thickness. Meanwhile, different electric field confinement along the capillary longitudinal axis can be achieved with different curvatures. Both effects significantly increase the sensitivity of the ring resonator for single nanoparticle detection. It is found that the sensitivity is enhanced about 10 times, as compared to that of a solid microsphere biosensor recently reported, and that the smallest detectable nanoparticle is estimated to be less than 20 nm in radius for a Δλ/λ resolution of 10(-8). The high sensitivity and the naturally integrated capillary based microfluidics make the OFRR a very promising sensing platform for detection of various nano-sized bio/chemical species in liquid as well as in air.

13.
J Imaging ; 6(7)2020 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34460662

RESUMO

Analysis of colonoscopy images plays a significant role in early detection of colorectal cancer. Automated tissue segmentation can be useful for two of the most relevant clinical target applications-lesion detection and classification, thereby providing important means to make both processes more accurate and robust. To automate video colonoscopy analysis, computer vision and machine learning methods have been utilized and shown to enhance polyp detectability and segmentation objectivity. This paper describes a polyp segmentation algorithm, developed based on fully convolutional network models, that was originally developed for the Endoscopic Vision Gastrointestinal Image Analysis (GIANA) polyp segmentation challenges. The key contribution of the paper is an extended evaluation of the proposed architecture, by comparing it against established image segmentation benchmarks utilizing several metrics with cross-validation on the GIANA training dataset. Different experiments are described, including examination of various network configurations, values of design parameters, data augmentation approaches, and polyp characteristics. The reported results demonstrate the significance of the data augmentation, and careful selection of the method's design parameters. The proposed method delivers state-of-the-art results with near real-time performance. The described solution was instrumental in securing the top spot for the polyp segmentation sub-challenge at the 2017 GIANA challenge and second place for the standard image resolution segmentation task at the 2018 GIANA challenge.

14.
Cardiovasc Res ; 116(13): 2069-2080, 2020 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-32031586

RESUMO

AIMS: ß-adrenergic receptors (ßARs) play pivotal roles in regulating cardiac excitation-contraction (E-C) coupling. Global signalling of ß1ARs up-regulates both the influx of Ca2+ through sarcolemmal L-type Ca2+ channels (LCCs) and the release of Ca2+ from the sarcoplasmic reticulum (SR) through the ryanodine receptors (RyRs). However, we recently found that ß2AR stimulation meditates 'offside compartmentalization', confining ß1AR signalling into subsarcolemmal nanodomains without reaching SR proteins. In the present study, we aim to investigate the new question, whether and how compartmentalized ß1AR signalling regulates cardiac E-C coupling. METHODS AND RESULTS: By combining confocal Ca2+ imaging and patch-clamp techniques, we investigated the effects of compartmentalized ßAR signalling on E-C coupling at both cellular and molecular levels. We found that simultaneous activation of ß2 and ß1ARs, in contrast to global signalling of ß1ARs, modulated neither the amplitude and spatiotemporal properties of Ca2+ sparks nor the kinetics of the RyR response to LCC Ca2+ sparklets. Nevertheless, by up-regulating LCC current, compartmentalized ß1AR signalling synchronized RyR Ca2+ release and increased the functional reserve (stability margin) of E-C coupling. In circumstances of briefer excitation durations or lower RyR responsivity, compartmentalized ßAR signalling, by increasing the intensity of Ca2+ triggers, helped stabilize the performance of E-C coupling and enhanced the Ca2+ transient amplitude in failing heart cells. CONCLUSION: Given that compartmentalized ßAR signalling can be induced by stress-associated levels of catecholamines, our results revealed an important, yet unappreciated, heart regulation mechanism that is autoadaptive to varied stress conditions.


Assuntos
Canais de Cálcio Tipo L/metabolismo , Sinalização do Cálcio , Cardiomegalia/metabolismo , Acoplamento Excitação-Contração , Contração Miocárdica , Miócitos Cardíacos/metabolismo , Receptores Adrenérgicos beta 1/metabolismo , Potenciais de Ação , Agonistas Adrenérgicos/farmacologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Cardiomegalia/fisiopatologia , Simulação por Computador , Modelos Animais de Doenças , Acoplamento Excitação-Contração/efeitos dos fármacos , Cinética , Masculino , Microscopia Confocal , Modelos Cardiovasculares , Contração Miocárdica/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Ratos Sprague-Dawley , Receptores Adrenérgicos beta 1/efeitos dos fármacos , Receptores Adrenérgicos beta 2/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo
15.
Opt Express ; 16(16): 11741-9, 2008 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-18679444

RESUMO

A novel optical sensor for label-free biomolecular binding assay using a one-dimensional photonic crystal in a total-internal-reflection geometry is proposed and demonstrated. The simple configuration provides a narrow optical resonance to enable sensitive measurements of molecular binding, and at the same time employs an open interface to enable real-time measurements of binding dynamics. Ultrathin aminopropyltriethoxysilane/ glutaraldehyde films adsorbed on the interface were detected by measuring the spectral shift of the photonic crystal resonance and the intensity ratio change in a differential reflectance measurement. A detection limit of 6 x 10(-5) nm for molecular layer thickness was obtained, which corresponds to a detection limit for analyte adsorption of 0.06 pg/mm(2) or a refractive index resolution of 3 x 10(-8) RIU; this represents a significant improvement relative to state-of-the-art surface-plasmon-resonance-based systems.


Assuntos
Biopolímeros/química , Técnicas Biossensoriais/instrumentação , Óptica e Fotônica/instrumentação , Fotometria/instrumentação , Mapeamento de Interação de Proteínas/métodos , Refratometria/instrumentação , Técnicas Biossensoriais/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Fotometria/métodos , Fótons , Ligação Proteica , Refratometria/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Circ Arrhythm Electrophysiol ; 11(8): e005913, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30354313

RESUMO

Background Papillary muscles are an important source of ventricular tachycardia (VT). Yet little is known about the role of the right ventricular (RV) endocavity structure, the moderator band (MB). The aim of this study was to determine the characteristics of the MB that may predispose to arrhythmia substrates. Methods Ventricular wedge preparations with intact MBs were studied from humans (n=2) and sheep (n=15; 40-50 kg). RV endocardium was optically mapped, and electrical recordings were measured along the MB and septum. S1S2 pacing of the RV free wall, MB, or combined S1-RV S2-MB sites were assessed. Human (n=2) and sheep (n=4) MB tissue constituents were assessed histologically. Results The MB structure was remarkably organized as 2 excitable, yet uncoupled compartments of myocardium and Purkinje. In humans, action potential duration heterogeneity between MB and RV myocardium was found (324.6±12.0 versus 364.0±8.4 ms; P<0.0001). S1S2-MB pacing induced unidirectional propagation via MB myocardium, permitting sustained macroreentrant VT. In sheep, the incidence of VT for RV, MB, and S1-RV S2-MB pacing was 1.3%, 5.1%, and 10.3%. Severing the MB led to VT termination, confirming a primary arrhythmic role. Inducible preparations had shorter action potential duration in the MB than RV (259.3±45.2 versus 300.7±38.5 ms; P<0.05), whereas noninducible preparations showed no difference (312.0±30.3 versus 310.0±24.6 ms, respectively). Conclusions The MB presents anatomic and electrical compartmentalization between myocardium and Purkinje fibers, providing a substrate for macroreentry. The vulnerability to sustain VT via this mechanism is dependent on MB structure and action potential duration gradients between the RV free wall and MB.


Assuntos
Potenciais de Ação , Frequência Cardíaca , Músculos Papilares/fisiopatologia , Taquicardia Ventricular/etiologia , Animais , Estimulação Cardíaca Artificial , Simulação por Computador , Técnicas Eletrofisiológicas Cardíacas , Humanos , Técnicas In Vitro , Modelos Cardiovasculares , Miocárdio/patologia , Músculos Papilares/patologia , Ramos Subendocárdicos/fisiopatologia , Carneiro Doméstico , Taquicardia Ventricular/diagnóstico , Taquicardia Ventricular/fisiopatologia , Fatores de Tempo , Imagens com Corantes Sensíveis à Voltagem
17.
Sci Bull (Beijing) ; 62(19): 1295-1303, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36659291

RESUMO

The elementary Ca2+ release events, Ca2+ sparks, has been found for a quarter of century. However, the molecular regulation of the spark generator, the ryanodine receptor (RyR) on the sarcoplasmic reticulum, remains obscure. Although each subunit of the RyR homotetramer has a site for FK506-binding protein (FKBP), the role of FKBPs in modifying RyR Ca2+ sparks has been debated for long. One of the reasons behind the controversy is that most previous studies detect spontaneous sparks, where the mixture with out-of-focus events and local wavelets prevents an accurate characterization of Ca2+ sparks. In the present study, we detected Ca2+ sparks triggered by single L-type Ca2+ channels (LCCs) under loose-seal patch clamp conditions in FK506-treated or FKBP12.6 knockout cardiomyocytes. We found that FKBP dissociation both by FK506 and by rapamycin decreased the Ca2+ spark amplitude in ventricular cardiomyocytes. This change was neither due to decreased releasable Ca2+ in the sarcoplasmic reticulum, nor explained by changed RyR sensitivity. Actually FK506 increased the LCC-RyR coupling probability and curtailed the latency for an LCC to trigger a RyR Ca2+ spark. FKBP12.6 knockout had similar effects as FK506/rapamycin treatment, indicating that the decreased spark amplitude was attributable to the dissociation of FKBP12.6 rather than FKBP12. We also explained how decreased amplitude of spontaneous sparks after FKBP dissociation sometimes appears to be increased or unchanged due to inappropriate data processing. Our results provided firm evidence that without the inter-RyR coordination by functional FKBP12.6, the RyR recruitment during a Ca2+ spark would be compromised despite the sensitization of individual RyRs.

18.
Cardiovasc Res ; 113(3): 332-342, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28077437

RESUMO

Aims: The heart contraction is controlled by the Ca2+-induced Ca2+ release (CICR) between L-type Ca2+ channels and ryanodine receptors (RyRs). The FK506-binding protein FKBP12.6 binds to RyR subunits, but its role in stabilizing RyR function has been debated for long. Recent reports of high-resolution RyR structure show that the HD2 domain that binds to the SPRY2 domain of neighbouring subunit in FKBP-bound RyR1 is detached and invisible in FKBP-null RyR2. The present study was to test the consequence of FKBP12.6 absence on the in situ activation of RyR2. Methods and results: Using whole-cell patch-clamp combined with confocal imaging, we applied a near threshold depolarization to activate a very small fraction of LCCs, which in turn activated RyR Ca2+ sparks stochastically. FKBP12.6-knockout and FK506/rapamycin treatments increased spark frequency and LCC-RyR coupling fidelity without altering LCC open probability. Neither FK506 nor rapamycin further altered LCC-RyR coupling fidelity in FKBP12.6-knockout cells. In loose-seal patch-clamp experiments, the LCC-RyR signalling kinetics, indexed by the delay for a LCC sparklet to trigger a RyR spark, was accelerated after FKBP12.6 knockout and FK506/rapamycin treatments. These results demonstrated that RyRs became more sensitive to Ca2+ triggers without FKBP12.6. Isoproterenol (1 µM) further accelerated the LCC-RyR signalling in FKBP12.6-knockout cells. The synergistic sensitization of RyRs by catecholaminergic signalling and FKBP12.6 dysfunction destabilized the CICR system, leading to chaotic Ca2+ waves and ventricular arrhythmias. Conclusion: FKBP12.6 keeps the RyRs from over-sensitization, stabilizes the potentially regenerative CICR system, and thus may suppress the life-threatening arrhythmogenesis.


Assuntos
Arritmias Cardíacas/metabolismo , Canais de Cálcio Tipo L/metabolismo , Sinalização do Cálcio , Miócitos Cardíacos/metabolismo , Receptor Cross-Talk , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Proteínas de Ligação a Tacrolimo/deficiência , Animais , Arritmias Cardíacas/genética , Arritmias Cardíacas/fisiopatologia , Arritmias Cardíacas/prevenção & controle , Canais de Cálcio Tipo L/química , Canais de Cálcio Tipo L/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Genótipo , Isoproterenol/farmacologia , Cinética , Masculino , Potenciais da Membrana , Camundongos Knockout , Microscopia Confocal , Modelos Moleculares , Miócitos Cardíacos/efeitos dos fármacos , Técnicas de Patch-Clamp , Fenótipo , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Receptor Cross-Talk/efeitos dos fármacos , Canal de Liberação de Cálcio do Receptor de Rianodina/química , Canal de Liberação de Cálcio do Receptor de Rianodina/efeitos dos fármacos , Sirolimo/farmacologia , Processos Estocásticos , Tacrolimo/farmacologia , Proteínas de Ligação a Tacrolimo/antagonistas & inibidores , Proteínas de Ligação a Tacrolimo/química , Proteínas de Ligação a Tacrolimo/genética
19.
Di Yi Jun Yi Da Xue Xue Bao ; 25(4): 413-5, 2005 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-15837641

RESUMO

OBJECTIVE: To establish a method by high-performance liquid chromatography (HPLC) for determining the concentration of magnetic mitomycin C-polybutylcyanoacrylate nanoparticles in mouse plasma. METHODS: Chromatography was performed on a LiChroCART C18 (250 mm x 4 mm, 5 microm) column with the mobile phase consisting of acetonitrile-NaAC (15:85), the flow rate of 1.0 ml/min, and the detection wavelength of 365 nm. Sample extraction was carried out with ethylacetate. RESULTS: The linear range of mouse plasma mitomycin C concentration was 0.04-1.00 microg/ml, and the linear equation of Y=16 388X-17.17 (r=0.999 8) was derived. CONCLUSION: This method is very easy to operate and suits the need of perclinical pharmacokinetic studies of mitomycin-magnetic nanoparticles and yields accurate and precise results.


Assuntos
Sistemas de Liberação de Medicamentos , Embucrilato , Mitomicina/sangue , Nanopartículas , Animais , Cromatografia Líquida de Alta Pressão , Portadores de Fármacos , Magnetismo , Camundongos , Mitomicina/administração & dosagem
20.
Opt Express ; 12(17): 4047-52, 2004 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-19483945

RESUMO

In this paper, the experiment on parallel correlated recognition of 2030 human faces in Fe:LiNbO(3) crystal is detailedly presented, a very clear correlation spots array was achieved and the recognition accuracy is better than 95%. According to the experiment, it is proved that speckle modulation on the object beam of volume holographic correlators can well suppress the crosstalk, so that the multiplexing spacing is markedly reduced and the channel density is increased 10 times compared with the traditional holographic correlators without speckle modulation.

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