162 research outputs found
Atrial cardiomyopathy: An emerging cause of the embolic stroke of undetermined source
Nearly 30% of ischemic strokes have an unknown cause, which are referred to as cryptogenic strokes (CS). Imaging studies suggest that a large proportion of these patients show features that are consistent with embolism, and thus the term embolic stroke of undetermined source (ESUS) was proposed to describe these CS patients. Atrial cardiomyopathy predisposes to thrombus formation and thus embolic stroke even in the absence of atrial fibrillation (AF). This may provide a mechanistic link with ESUS, suggesting that anticoagulant therapy may be more beneficial than antiplatelet therapy in ESUS patients with atrial cardiomyopathy. The present review discusses the concept of atrial cardiomyopathy and ESUS and the relationship between them based on the mechanisms and clinical evidence, suggests that atrial cardiomyopathy may be a potential mechanism of ESUS, and highlights a theoretical basis that supports that anticoagulant therapy may be more applicable to ESUS patients with atrial cardiomyopathy and aims to help us better understand and identify the risk of ESUS, thereby improving the management of these patients in clinical practice
Motion-enhanced Holography
Holographic displays, which enable pixel-level depth control and aberration
correction, are considered the key technology for the next-generation virtual
reality (VR) and augmented reality (AR) applications. However, traditional
holographic systems suffer from limited spatial bandwidth product (SBP), which
makes them impossible to reproduce \textit{realistic} 3D displays.
Time-multiplexed holography creates different speckle patterns over time and
then averages them to achieve a speckle-free 3D display. However, this approach
requires spatial light modulators (SLMs) with ultra-fast refresh rates, and
current algorithms cannot update holograms at such speeds. To overcome the
aforementioned challenge, we proposed a novel architecture, motion-enhanced
holography, that achieves \textit{realistic} 3D holographic displays without
artifacts by continuously shifting a special hologram. We introduced an
iterative algorithm to synthesize motion-enhanced holograms and demonstrated
that our method achieved a 10 dB improvement in the peak signal-to-noise ratio
(PSNR) of 3D focal stacks in numerical simulations compared to traditional
holographic systems. Furthermore, we validated this idea in optical experiments
utilizing a high-speed and high-precision programmable three-axis displacement
stage to display full-color and high-quality 3D focal stacks.Comment: 10 pages, 5 figure
Photoelectrochemical and electrochemical ratiometric aptasensing: a case study of streptomycin
There has been much interest in constructing ratiometric sensors using different sensing techniques because of
their synergistic effect, although the simultaneous collection of the signals is challenging. Herein, we propose a
ratiometric aptasensing strategy based on the dual-detection model with a photoelectrochemical (PEC) “signalon” and an electrochemical (EC) “signal-off”. As a proof-of-concept study, CdTe quantum dots (CdTe QDs) and a
methylene blue-labeled aptamer (MB-Apt) were used to generate PEC and EC signals in the sensing system. The
target-induced conformational change of MB-Apt pushed MB away from the electrode, thereby decreasing the EC
signal; at the same time, the reduced steric hindrance favored the restoration of the PEC signal from the CdTe
QDs. Thus, this PEC-EC strategy can achieve the PEC “signal-on” and EC “signal-off” states simultaneously, as
well as allowing quantitative analysis of the target based on the ratio of the current intensities. As a model
application, an aptasensor fabricated for streptomycin detection showed a wide linear range from 0.03 to 100 μM
with a detection limit of 10 nM (S/N = 3). The proposed sensing platform displayed superior analytical properties compared with methods based on PEC or EC alone. Our work provides an efficient dual-detection modelbased ratiometric strategy for advanced analysis, and paves the way to the simultaneous acquisition of signals
Frequency-aware optical coherence tomography image super-resolution via conditional generative adversarial neural network
Optical coherence tomography (OCT) has stimulated a wide range of medical
image-based diagnosis and treatment in fields such as cardiology and
ophthalmology. Such applications can be further facilitated by deep
learning-based super-resolution technology, which improves the capability of
resolving morphological structures. However, existing deep learning-based
method only focuses on spatial distribution and disregard frequency fidelity in
image reconstruction, leading to a frequency bias. To overcome this limitation,
we propose a frequency-aware super-resolution framework that integrates three
critical frequency-based modules (i.e., frequency transformation, frequency
skip connection, and frequency alignment) and frequency-based loss function
into a conditional generative adversarial network (cGAN). We conducted a
large-scale quantitative study from an existing coronary OCT dataset to
demonstrate the superiority of our proposed framework over existing deep
learning frameworks. In addition, we confirmed the generalizability of our
framework by applying it to fish corneal images and rat retinal images,
demonstrating its capability to super-resolve morphological details in eye
imaging.Comment: 13 pages, 7 figures, submitted to Biomedical Optics Express special
issu
Atrial cardiomyopathy: from cell to bedside
Atrial cardiomyopathy refers to structural and electrical remodelling of the atria, which can lead to impaired mechanical function. While historical studies have implicated atrial fibrillation as the leading cause of cardioembolic stroke, atrial cardiomyopathy may be an important, underestimated contributor. To date, the relationship between atrial cardiomyopathy, atrial fibrillation, and cardioembolic stroke remains obscure. This review summarizes the pathogenesis of atrial cardiomyopathy, with a special focus on neurohormonal and inflammatory mechanisms, as well as the role of adipose tissue, especially epicardial fat in atrial remodelling. It reviews the current evidence implicating atrial cardiomyopathy as a cause of embolic stroke, with atrial fibrillation as a lagging marker of an increased thrombogenic atrial substrate. Finally, it discusses the potential of antithrombotic therapy in embolic stroke with undetermined source and appraises the available diagnostic techniques for atrial cardiomyopathy, including imaging techniques such as echocardiography, computed tomography, and magnetic resonance imaging as well as electroanatomic mapping, electrocardiogram, biomarkers, and genetic testing. More prospective studies are needed to define the relationship between atrial cardiomyopathy, atrial fibrillation, and embolic stroke and to establish a prompt diagnosis and specific treatment strategies in these patients with atrial cardiomyopathy for the secondary and even primary prevention of embolic stroke
Cardiovascular disease during the COVID-19 pandemic: Think ahead, protect hearts, reduce mortality
Coronavirus disease 2019 (COVID-19) is rapidly spreading globally. As of October 3, 2020, the number of confirmed cases has been nearly 34 million with more than 1 million fatalities. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is accountable for COVID-19. Newly diagnosed and worsening cardiovascular disease are common complications in COVID-19 patients, including acute cardiac injury, hypertension, arrhythmia, myocardial infarction, heart failure and sudden cardiac arrest. The mechanisms contributing to cardiac disease burden include hypoxemia, inflammatory factor storm, dysfunctional angiotensin converting enzyme 2 (ACE2), and drug-induced cardiac toxicity.Notably, the macrophages expressing ACE2 as direct host cells of SARS-CoV-2 secrete chemokine and inflammatory cytokines, as well as a decrease in cellular immune responses to SARS-CoV-2 infection due to elevated exhaustion levels and dysfunctional diversity of T cells, that may be accountable for the “hyperinflammation and cytokine storm syndrome” and subsequently acute cardiac injury and deterioratingcardiovascular disease in COVID-19 patients. However, no targeted medication or vaccines for COVID-19 are yet available. The management of cardiovascular disease in patients with COVID-19 include general supportive treatment, circulatory support, other symptomatic treatment, psychological assistance as well as online consultation. Further work should be concentrated on better understanding the pathogenesis of COVID-19 and accelerating the development of drugs and vaccines to reduce the cardiac disease burden and promote the management of COVID-19 patients, especially those with a severe disease course and cardiovascular complications
Penicillium marneffei-Stimulated Dendritic Cells Enhance HIV-1 Trans-Infection and Promote Viral Infection by Activating Primary CD4+ T Cells
Penicillium marneffei (P. marneffei) is considered an indicator pathogen of AIDS, and the endemicity and clinical features of P. marneffei have been described. While, how the co-infection of P. marneffei exacerbate deterioration of the immune response remains poorly understood. Here we isolated P. marneffei from the cutaneous lesions of AIDS patients and analyzed its effects on HIV-1-dendritic cells (DCs) interaction. We demonstrated that the monocyte-derived dendritic cells (MDDCs) could be activated by both thermally dimorphic forms of P. marneffei for significantly promoting HIV-1 trans-infection of CD4+ T cells, while these activated MDDCs were refractory to HIV-1 infection. Mechanistically, P. marneffei-activated MDDCs endocytosed large amounts of HIV-1 and sequestrated the internalized viruses into tetrapasnin CD81+ compartments potentially for proteolysis escaping. The activated MDDCs increased expression of intercellular adhesion molecule 1 and facilitated the formation of DC-T-cell conjunctions, where much more viruses were recruited. Moreover, we found that P. marneffei-stimulated MDDCs efficiently activated resting CD4+ T cells and induced more susceptible targets for viral infection. Our findings demonstrate that DC function and its interaction with HIV-1 have been modulated by opportunistic pathogens such as P. marneffei for viral dissemination and infection amplification, highlighting the importance of understanding DC-HIV-1 interaction for viral immunopathogenesis elucidation
Atrial cardiomyopathy: from cell to bedside.
Atrial cardiomyopathy refers to structural and electrical remodelling of the atria, which can lead to impaired mechanical function. While historical studies have implicated atrial fibrillation as the leading cause of cardioembolic stroke, atrial cardiomyopathy may be an important, underestimated contributor. To date, the relationship between atrial cardiomyopathy, atrial fibrillation, and cardioembolic stroke remains obscure. This review summarizes the pathogenesis of atrial cardiomyopathy, with a special focus on neurohormonal and inflammatory mechanisms, as well as the role of adipose tissue, especially epicardial fat in atrial remodelling. It reviews the current evidence implicating atrial cardiomyopathy as a cause of embolic stroke, with atrial fibrillation as a lagging marker of an increased thrombogenic atrial substrate. Finally, it discusses the potential of antithrombotic therapy in embolic stroke with undetermined source and appraises the available diagnostic techniques for atrial cardiomyopathy, including imaging techniques such as echocardiography, computed tomography, and magnetic resonance imaging as well as electroanatomic mapping, electrocardiogram, biomarkers, and genetic testing. More prospective studies are needed to define the relationship between atrial cardiomyopathy, atrial fibrillation, and embolic stroke and to establish a prompt diagnosis and specific treatment strategies in these patients with atrial cardiomyopathy for the secondary and even primary prevention of embolic stroke
Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation
We report fabrication method and THz characterization of composite films
containing either aligned metallic (tin alloy) microwires or chalcogenide
As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber
fabrication technique using multi-step co-drawing of low-melting-temperature
metals or semiconductor glasses together with polymers. Fibers are then stacked
together and pressed into composite films. Transmission through metamaterial
films is studied in the whole THz range (0.1-20 THz) using a combination of
FTIR and TDS. Metal containing metamaterials are found to have strong
polarizing properties, while semiconductor containing materials are
polarization independent and could have a designable high refractive index.
Using the transfer matrix theory, we show how to retrieve the complex
polarization dependent refractive index of the composite films. We then detail
the selfconsistent algorithm for retrieving the optical properties of the metal
alloy used in the fabrication of the metamaterial layers by using an effective
medium approximation. Finally, we study challenges in fabrication of
metamaterials with sub-micrometer metallic wires by repeated stack-and-draw
process by comparing samples made using 2, 3 and 4 consecutive drawings. When
using metallic alloys we observe phase separation effects and nano-grids
formation on small metallic wires
Mesoporous WO3 Nanofibers With Crystalline Framework for High-Performance Acetone Sensing
Semiconducting metal oxides with abundant active sites are regarded as promising candidates for environmental monitoring and breath analysis because of their excellent gas sensing performance and stability. Herein, mesoporous WO3 nanofibers with a crystalline framework and uniform pore size is successfully synthesized in an aqueous phase using an electrospinning method, with ammonium metatungstate as the tungsten sources, and SiO2 nanoparticles and polyvinylpyrrolidone as the sacrificial templates. The obtained mesoporous WO3 nanofibers exhibit a controllable pore size of 26.3–42.2 nm, specific surface area of 24.1–34.4 m2g−1, and a pore volume of 0.15–0.24 cm3g−1. This unique hierarchical structure, with uniform mesopores and interconnected channels, could facilitate the diffusion and transportation of gas molecules in the framework. Gas sensors, based on mesoporous WO3 nanofibers, exhibit an excellent performance in acetone sensing with a low limit of detection (<1 ppm), short response-recovery time (24 s/27 s), a linear relationship in a broad range, and good selectivity
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