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Retinal oxygen extraction during systemic hypoxia assessed with laser-speckle flowgraphy and retinal oximetry

ACTA OPHTHALMOLOGICA 2025年第S284期103卷

作者： Pai, Viktoria Lindner, Theresa Janku, Patrick Schmetterer, Leopold Schmidl, Doreen Garhofer, Gerhard Department of Clinical Pharmacology Medical University of Vienna Vienna Austria Singapore National Eye Centre Singapore Eye Research Institute Singapore Singapore Duke-NUS Medical School Ophthalmology and Visual Sciences Academic Clinical Program Singapore Singapore SERI-NTU Advanced Ocular Engineering (STANCE) Nanyang Technological University Singapore Singapore Center for Medical Physics and Biomedical Engineering Medical University of Vienna Vienna Austria Institute of Molecular and Clinical Ophthalmology Basel Switzerland School of Chemistry Chemical Engineering and Biotechnology Nanyang Technological University Singapore Singapore

Aims/Purpose: Retinal oxygen extraction has been found to be altered in several ocular and systemic diseases, such as diabetic retinopathy, glaucoma or neurodegenerative diseases. However, measurement techniques for the assessment of retinal oxygen extraction are limited because most of them are based on time-consuming and custom-built devices. In the present pilot study, we assessed retinal oxygen extraction during systemic hypoxia with a combination of two commercially available devices: Laser-Speckle Flowgraphy (LSFG) and retinal oximetry. Methods: Retinal blood flow and retinal oxygen saturation were measured in each vessel around the optic nerve head at the same position. Arterial and venous oxygen content was estimated from the measured retinal oxygen saturation parameters and the difference between these two parameters was calculated (cO 2 , DIFF ). By using mean vessel flow rate (MV) for retinal blood flow and cO 2 , DIFF , retinal oxygen extraction was determined. For each healthy study participant, baseline measurement and measurement during inhalation of 88% nitrogen in 12% oxygen were performed. Results: Ten (10) healthy subjects (4 females, 6 males) with a mean age of 27 ± 3 years were included in this study. During systemic hypoxia, a significant decrease in arterial oxygen content occurred ( p = 0.046) while venous oxygen content did not change, leading to a decrease in cO 2 , DIFF . As expected, this was accompanied by a significant increase in MV ( p = 0.014). No change in retinal oxygen extraction was observed (46 ± 8 a.u. at baseline vs. 46 ± 5 a.u. during hypoxia, p = 0.997). Conclusions: Breathing of 88% nitrogen in 12% oxygen caused a significant decrease in retinal arterial oxygen content. This was compensated by an increase in retinal blood flow in order to keep retinal oxygen extraction constant. This was physiologically expected, and these findings are consistent with the literature. Therefore, the presented approach for measurement of reti

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Error Sampling and Synthesis for High-Order Node Movement

Error Sampling and Synthesis for High-Order Node Movement

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Sanjaya, Devina P. Rangarajan, Ajay Ollivier-Gooch, Carl F. Scientific Computing and Fluid Dynamics Lab Department of Mechanical Aerospace & Biomedical Engineering University of Tennessee KnoxvilleTN37996 United States Graduate School AICES RWTH Aachen University Aachen52062 Germany Advanced Numerical Simulation Laboratory Department of Mechanical Engineering University of British Columbia VancouverBCV6T1Z4 Canada

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The presented work focuses on the error sampling and synthesis procedure within an optimization framework for high-order, metric-based mesh adaptation in high-order, finiteelement (FEM) discretization. This mesh optimization framework is designed to handle arbitrary FEM discretization order, geometry order, and element types. In performing a metric-based adaptation, the framework uses a high-order Riemannian metric field to encode the curvature, anisotropy, and global coupling between vertices and high-order geometry nodes. An error model and a cost model are employed to iteratively construct the desired Riemannian metric field and guide a series of globally coupled vertex (r-adaptation) and high-order geometry (q-adaptation) node movements. The resulting mesh is an optimal high-order (curved) mesh that conforms to the specified metric field. The error model requires an error sampling and synthesis procedure, which involves several steps, including element splitting, random sampling of high-order geometry node movements, and estimating the metric-based error kernel on each mesh element. This paper aims to: 1) discuss the theoretical underpinnings of a robust, a posteriori, metric-based error model for qr-adaptation and 2) provide a status update on the 1D HOMES algorithm, which is a native extension of the Mesh Optimization via Error Sampling and Synthesis (MOESS) algorithm to a higher order. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Mesh generation

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IIWM (Integration ImageJ with MATLAB) program for Segmentation and Volume Estimation in Ultrasound Biomicroscopic Images of Mouse Colon Tumor

IIWM (Integration ImageJ with MATLAB) Program for Segmentati...

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Ultrasonics Symposium (LAUS), IEEE UFFC Latin America

作者： Igor Soares Colonna Yasmin Farias Romi de Sant'Anna Rodrigo Pereira de Oliveira João Carlos Machado Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil INFNET Institute Rio de Janeiro Brazil Department of Surgery Biomedical Engineering Program/COPPE and Post-Graduation Program in Surgical Sciences School of Medicine Federal University of Rio de Janeiro Rio de Janeiro Brazil

ISBN: (数字)9798350349085

ISBN: (纸本)9798350349092

This article proposes the creation, implementation and development of an integration plugin for ImageJ that makes calls in MATLAB functions for the segmentation UBM imagens, more specific endoluminal (eUBM) e transabdominal (tUBM), in the laboratory the images are generating with frequencies between 30-40 MHZ. These images allow view colon layer, identify tumors in colons, to calculate tumor volume and 3D visualization. This integration may to improve the time taken to perform the procedure and the user experience to reduce the number of tasks and change windows, making the experience more fluid and with less risk of errors.

关键词： Solid modeling Image segmentation Visualization Ultrasonic imaging Three-dimensional displays Biological system modeling Volume measurement

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A Survey of Camouflaged Object Detection and Beyond

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CAAI Artificial Intelligence Research 2024年第1期3卷 1-30页

作者： Fengyang Xiao Sujie Hu Yuqi Shen Chengyu Fang Jinfa Huang Longxiang Tang Ziyun Yang Xiu Li Chunming He Tsinghua Shenzhen International Graduate School Tsinghua UniversityShenzhen 518055China Department of Biomedical Engineering Duke UniversityDurhamNC 27708USA School of Electrical and Computer Engineering Peking UniversityShenzhen 518055China

Camouflaged object detection(COD)refers to the task of identifying and segmenting objects that blend seamlessly into their surroundings,posing a significant challenge for computer vision *** recent years,COD has garnered widespread attention due to its potential applications in surveillance,wildlife conservation,autonomous systems,and *** several surveys on COD exist,they often have limitations in terms of the number and scope of papers covered,particularly regarding the rapid advancements made in the field since *** address this void,we present the most comprehensive review of COD to date,encompassing both theoretical frameworks and practical contributions to the *** paper explores various COD methods across four domains,including both image-level and video-level solutions,from the perspectives of traditional and deep learning *** thoroughly investigate the correlations between COD and other camouflaged scenario methods,thereby laying the theoretical foundation for subsequent ***,we delve into novel tasks such as referring-based COD and collaborative COD,which have not been fully addressed in previous *** object-level detection,we also summarize extended methods for instance-level tasks,including camouflaged instance segmentation,counting,and ***,we provide an overview of commonly used benchmarks and evaluation metrics in COD tasks,conducting a comprehensive evaluation of deep learning-based techniques in both image and video domains,considering both qualitative and quantitative ***,we discuss the limitations of current COD models and propose 9 promising directions for future research,focusing on addressing inherent challenges and exploring novel,meaningful *** comprehensive examination aims to deepen the understanding of COD models and related methods in camouflaged *** those interested,a curated list of CODrelated techniques,datasets,and addit

关键词： camouflaged object detection camouflaged scenario understanding deep learning artificial intelligence

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Ultrasonic interfacial crosslinking of TiO2-based nanocomposite hydrogels through thiol-norbornene reactions for sonodynamic antibacterial treatment

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Biomaterials Science 2023年第12期11卷 4184-4199页

作者： Yang, Su-Rung Wang, Reuben Yan, Chen-Jie Lin, Yi-Yun Yeh, Yu-Jia Yeh, Ying-Yu Yeh, Yi-Cheun Institute of Polymer Science and Engineering National Taiwan University Taipei Taiwan Institute of Food Safety and Health National Taiwan University Taipei Taiwan Master of Public Health Program National Taiwan University Taipei Taiwan GIP-TRIAD Master's Degree in Agro-Biomedical Science National Taiwan University Taipei Taiwan

Nanocomposite (NC) hydrogels used for sonodynamic therapy (SDT) face challenges such as lacking interfacial interactions between the polymers and nanomaterials as well as presenting uneven dispersion of nanomaterials in the hydrogel network, reducing their mechanical properties and treatment efficiency. Here, we demonstrate a promising approach of co-engineering nanomaterials and interfacial crosslinking to expand the materials construction and biomedical applications of NC hydrogels in SDT. In this work, mesoporous silica-coated titanium dioxide nanoparticles with thiolated surface functionalization (TiO2@MS-SH) are utilized as crosslinkers to react with norbornene-functionalized dextran (Nor-Dex) through ultrasound-triggered thiol-norbornene reactions, forming TiO2@MS-SH/Nor-Dex NC hydrogels. The TiO2@MS-SH nanoparticles act not only as multivalent crosslinkers to improve the mechanical properties of hydrogels under ultrasound irradiation but also as reactive oxygen species (ROS) generators to allow the use of TiO2@MS-SH/Nor-Dex NC hydrogels in SDT applications. Particularly, the TiO2@MS-SH/Nor-Dex NC hydrogels present tailorable microstructures, properties, and sonodynamic killing of bacteria through the modulation of the ultrasound frequency. Taken together, a versatile TiO2-based NC hydrogel platform prepared under ultrasonic interfacial crosslinking reactions is developed for advancing the applications in SDT. © 2023 The Royal Society of Chemistry.

关键词： Titanium dioxide

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Optimization of the in vitro biodegradability,cytocompatibility,and wear resistance of the AZ31B alloy by micro-arc oxidation coatings doped with zinc phosphate

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Journal of Materials Science & Technology 2024年第12期179卷 224-239页

作者： Chao Yang Suihan Cui Ricky KYFu Liyuan Sheng Min Wen Daokui Xu Ying Zhao Yufeng Zheng Paul KChu Zhongzhen Wu School of Advanced Materials Peking University Shenzhen Graduate SchoolShenzhen 518055China Department of Physics Department of Materials Science&Engineeringand Department of Biomedical EngineeringCity University of Hong KongTat Chee AvenueKowloonHong Kong 999077China Shenzhen Institute Peking UniversityShenzhen 518057China PKU-HKUST Shenzhen–Hong Kong Institution Shenzhen 518057China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055China National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite Shanghai Jiao Tong UniversityShanghai 200240China

As implanted bone fixation materials,magnesium(Mg)alloys have significant advantages because the density and elastic modulus are closest to those of the human bone and they can bio-degrade in the physiological ***,Mg alloys degrade too rapidly and uncontrollably thus hampering clinical *** this study,a highly corrosion-resistant zinc-phosphate-doped micro-arc oxidation(MAO)coating is prepared on the AZ31B alloy,and the degradation process is assessed in *** increasing zinc phosphate concentrations,both the corrosion potentials and charge transfer resistance of the AZ31B alloy coated with MAO coatings increase gradually,while the corrosion current densities di-minish *** tests in the simulated body fluid(SBF)reveal that the increased zinc phos-phate concentration in MAO coating decreases the degradation rate,consequently reducing the release rates of Mg^(2+)and OH-in the physiological micro-environment,which obtains the lowest weight loss of only 5.22%after immersion for 56 *** regulation of degradation provides a weak alkaline environment that is suitable for long-term cell growth and subsequent promotion of bone proliferation,differentiation,mineralization,and *** addition,the zinc-phosphate-doped MAO coat-ings show an improved wear resistance as manifested by a wear rate of only 3.81 x 10^(-5) mm^(3) N^(-1) m^(-1).The results reveal a suitable strategy to improve the properties of biodegradable Mg alloys to balance tissue healing with mechanical degradation.

关键词： Mg alloys MAO coatings Degradation regulation Cytocompatibility Wear resistance

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Low-dose intrapulmonary drug delivery device for studies on next-generation therapeutics in mice

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Journal of Controlled Release 2023年 359卷 287-301页

作者： Gracioso Martins, Ana Maria Snider, Douglas B. Popowski, Kristen D. Schuchard, Karl G. Tenorio, Matias Akunuri, Sandip Wee, Junghyun Peters, Kara J. Jansson, Anton Shirwaiker, Rohan Cheng, Ke Freytes, Donald O. Cruse, Glenn P. Department of Molecular Biomedical Sciences College of Veterinary Medicine North Carolina State University RaleighNC United States Comparative Medicine and Translational Research Training Program North Carolina State University RaleighNC United States Comparative Medicine Institute North Carolina State University RaleighNC United States Joint Department of Biomedical Engineering College of Engineering North Carolina State University & University of North Carolina-Chapel Hill NC United States Edward P. Fitts Department of Industrial and Systems Engineering North Carolina State University RaleighNC United States Department of Mechanical and Aerospace Engineering North Carolina State University RaleighNC United States Analytical Instrumentation Facility Monteith Research Center North Carolina State University RaleighNC United States

Although nebulizers have been developed for delivery of small molecules in human patients, no tunable device has been purpose-built for targeted delivery of modern large molecule and temperature-sensitive therapeutics to mice. Mice are used most of all species in biomedical research and have the highest number of induced models for human-relevant diseases and transgene models. Regulatory approval of large molecule therapeutics, including antibody therapies and modified RNA highlight the need for quantifiable dose delivery in mice to model human delivery, proof-of-concept studies, efficacy, and dose-response. To this end, we developed and characterized a tunable nebulization system composed of an ultrasonic transducer equipped with a mesh nebulizer fitted with a silicone restrictor plate modification to control the nebulization rate. We have identified the elements of design that influence the most critical factors to targeted delivery to the deep lungs of BALB/c mice. By comparing an in silico model of the mouse lung with experimental data, we were able to optimize and confirm the targeted delivery of over 99% of the initial volume to the deep portions of the mouse lung. The resulting nebulizer system provides targeted lung delivery efficiency far exceeding conventional nebulizers preventing waste of expensive biologics and large molecules during proof-of-concept and pre-clinical experiments involving mice. (Word Count =207). © 2023 Elsevier B.V.

关键词： Molecules

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Hyperspectral Image Analysis Using Maximum Abundance Classification

Hyperspectral Image Analysis Using Maximum Abundance Classif...

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International Conference on Intelligent Control and Information Processing (ICICIP)

作者： Nian Zhang Sougre-Nonma Stephanie Rouamba Wagdy H. Mahmoud Lara A. Thompson Department of Electrical and Computer Engineering University of the District of Columbia Washington D.C. USA Department of Mechanical Engineering Biomedical Engineering Program University of the District of Columbia Washington D.C. USA

ISBN: (数字)9798331516147

ISBN: (纸本)9798331516154

This paper presents a satellite hyperspectral image processing method that utilizes a maximum abundance classifier to categorize different regions of hyperspectral images into ground truth classes. First, the class names for each endmember and their corresponding columns in the signature matrix are identified, followed by the visualization of their spectral profiles. Abundance maps for the endmembers are then generated using the fully constrained least squares (FCLS) method. Afterward, the maximum abundance classifier is applied, and the resulting classified image is displayed with color-coded pixels. The abundance maps illustrate the spatial distribution of endmembers across the hyperspectral image, where the abundance values of each pixel represent the proportion of each endmember present. By determining the highest abundance value for each pixel and assigning it to the corresponding endmember class, the pixels within the hyperspectral images are classified. Experimental results demonstrate that the proposed MAC method effectively handles mixed pixels. In addition, it can effectively deal with the mixed pixel problem in hyperspectral images because it identifies components by calculating the abundance values for each pixel rather than relying solely on single spectral features.

关键词： Visualization Image segmentation Satellites Graphical models Information processing Hyperspectral imaging Intelligent control Image classification Distribution functions

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Ultrasound Stimulation Potentiates Management of Diabetic Hyperglycemia

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Ultrasound in Medicine and Biology 2023年第5期49卷 1259-1267页

作者： Chang, Chia-Hsuan Fan, Kang-Chih Cheng, Yuan-Pin Chen, Jung-Chih Chen, Gin-Shin Graduate Degree Program of the College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu City Taiwan Institute of Biomedical Engineering and Nanomedicine National Health Research Institutes Miaoli County Taiwan Division of Endocrinology and Metabolism Department of Internal Medicine National Taiwan University Hospital Hsinchu Branch Hsinchu City Taiwan Graduate Institute of Clinical Medicine College of Medicine National Taiwan University Taipei City Taiwan Electronic Systems Research Division National Chung-Shan Institute of Technology Taoyuan City Taiwan Institute of Biomedical Engineering National Yang Ming Chiao Tung University Hsinchu City Taiwan Department of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu City Taiwan Catholic Mercy Hospital Catholic Mercy Medical Foundation Hsinchu County Taiwan Medical Device Innovation & Translation Center National Yang Ming Chiao Tung University Hsinchu City Taiwan

Objective: Glucose homeostasis is the only way to manage diabetic progression as all medications used do not cure diabetes. This study was aimed at verifying the feasibility of lowering glucose with non-invasive ultrasonic stimulation. Methods: The ultrasonic device was homemade and controlled via a mobile application on the smartphone. Diabetes was induced in Sprague–Dawley rats through high-fat diets followed by streptozotocin injection. The treated acupoint CV12 was at the middle of the xiphoid and umbilicus of the diabetic rats. Parameters of ultrasonic stimulation were an operating frequency of 1 MHz, pulse repetition frequency of 15 Hz, duty cycle of 10% and sonication time of 30 min for a single treatment. Discussion: The diabetic rats exhibited a significant decrease of 11.5% ± 3.6% in blood glucose in 5 min of ultrasonic stimulation (p © 2023 World Federation for Ultrasound in Medicine & Biology

关键词： Glucose

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RU-Net: skull stripping in rat brain MR images after ischemic stroke with rat U-Net

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BMC Medical Imaging 2023年第1期23卷 1-14页

作者： Chang, Herng-Hua Yeh, Shin-Joe Chiang, Ming-Chang Hsieh, Sung-Tsang Computational Biomedical Engineering Laboratory (CBEL) Department of Engineering Science and Ocean Engineering National Taiwan University No. 1 Sec. 4 Roosevelt Road Taipei Daan 10617 Taiwan Department of Neurology and Stroke Center National Taiwan University Hospital Taipei 10002 Taiwan Department of Biomedical Engineering National Yang Ming Chiao Tung University Taipei 11221 Taiwan Graduate Institute of Anatomy and Cell Biology College of Medicine National Taiwan University Taipei 10051 Taiwan Graduate Institute of Clinical Medicine College of Medicine National Taiwan University Taipei 10051 Taiwan Graduate Institute of Brain and Mind Sciences College of Medicine National Taiwan University Taipei 10051 Taiwan Center of Precision Medicine College of Medicine National Taiwan University Taipei 10051 Taiwan

Background: Experimental ischemic stroke models play a fundamental role in interpreting the mechanism of cerebral ischemia and appraising the development of pathological extent. An accurate and automatic skull stripping tool for rat brain image volumes with magnetic resonance imaging (MRI) are crucial in experimental stroke analysis. Due to the deficiency of reliable rat brain segmentation methods and motivated by the demand for preclinical studies, this paper develops a new skull stripping algorithm to extract the rat brain region in MR images after stroke, which is named Rat U-Net (RU-Net). Methods: Based on a U-shape like deep learning architecture, the proposed framework integrates batch normalization with the residual network to achieve efficient end-to-end segmentation. A pooling index transmission mechanism between the encoder and decoder is exploited to reinforce the spatial correlation. Two different modalities of diffusion-weighted imaging (DWI) and T2-weighted MRI (T2WI) corresponding to two in-house datasets with each consisting of 55 subjects were employed to evaluate the performance of the proposed RU-Net. Results: Extensive experiments indicated great segmentation accuracy across diversified rat brain MR images. It was suggested that our rat skull stripping network outperformed several state-of-the-art methods and achieved the highest average Dice scores of 98.04% (p < 0.001) and 97.67% (p < 0.001) in the DWI and T2WI image datasets, respectively. Conclusion: The proposed RU-Net is believed to be potential for advancing preclinical stroke investigation and providing an efficient tool for pathological rat brain image extraction, where accurate segmentation of the rat brain region is fundamental. © 2023, The Author(s).

关键词： Brain segmentation Deep learning Ischemic stroke MRI Skull stripping U-Net

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