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Optogenetic stimulation of Gs-signaling in the heart with high spatio-temporal precision
摘要： The standard technique for investigating adrenergic effects on heart function is perfusion with pharmaceutical agonists, which does not provide high temporal or spatial precision. Herein we demonstrate that the light sensitive Gs-protein coupled receptor JellyOp enables optogenetic stimulation of Gs-signaling in cardiomyocytes and the whole heart. Illumination of transgenic embryonic stem cell-derived cardiomyocytes or of the right atrium of mice expressing JellyOp elevates cAMP levels and instantaneously accelerates spontaneous beating rates similar to pharmacological β-adrenergic stimulation. Light application to the dorsal left atrium instead leads to supraventricular extrabeats, indicating adverse effects of localized Gs-signaling. In isolated ventricular cardiomyocytes from JellyOp mice, we find increased Ca2+ currents, fractional cell shortening and relaxation rates after illumination enabling the analysis of differential Gs-signaling with high temporal precision. Thus, JellyOp expression allows localized and time-restricted Gs stimulation and will provide mechanistic insights into different effects of site-specific, long-lasting and pulsatile Gs activation.
关键词： β-adrenergic stimulation,Optogenetic stimulation,spatio-temporal precision,JellyOp,Gs-signaling,cAMP,cardiomyocytes,heart
更新于2025-11-21 11:24:58
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High tension electrocution death: New histopathological cardiac tools by Confocal Laser Scanning Microscope
摘要： In deaths due to electrocution intraepidermal separation, vacuolation of epidermal cells, “swiss cheese” aspect of the superficial part of epidermis (swollen and with multiple vescicles), metallization, necrosis of collagenous fibers, cardiomyocytes alterations are microscopically described. No cardiac nerve damage due to electricity is actually reported in literature. In this work we tried to find new morphological signs in the hearts of deaths due to electrocution. In three cases of deaths due to electrocution, in which forensic autopsies were performed within 36 h of the death, heart specimens were taken at the level of common trunk of the left coronary artery. The myocardium histological examination at optical microscope and Confocal Laser Scanning Microscope (CLSM) revealed fragmentation of cardiomyocytes, nerve trunks damage with hydropic swelling of the nerve fibers, interstitial and sub-nerve-sheath edema, very dishomogenous distribution of the natural fluorescence of the neurofilaments, coarctation of epicardial gangliar cells with cytoplasmic cleft and irregular fluorescence pattern. Identification of S-100 protein by immunohistochemistry can help to better observe the hydropic swelling of the nerve fibers and the central cytoplasmic clefts. These alterations could be used in future as specific signs of the passage of the electrical current through the heart. We recommend heart specimens at the level of common trunk of the left coronary artery in all the cases of suspected electrocution, to better evaluate cardiac nerve trunks damages and alterations.
关键词： Confocal laser scanning microscope (CLSM),Histology,Cardiac nerves,Electrocution,Fluorescence,Heart
更新于2025-11-21 11:20:42
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Real-time signal processing of photoplethysmographic signals to estimate the on-demand and continuous heart rate by spectral analysis
摘要： In healthcare applications, heart rate is one of the vital signs which give the health informatics of a person. Nowadays, the evolution of PPG sensors help to develop low cost heart rate monitoring devices with minimal hardware resources compared to ECG. In this paper, an efficient algorithm is proposed to find the heart rate using frequency spectrum analysis on PPG signals. Using the proposed algorithm, the heart rate is calculated with a pass percentage of 99.2, mean absolute percentage error (MAPE) of 1.59%, mean absolute error (MAE) of 1.20 BPM and reference closeness factor (RCF) of 0.989. The first reliable heart rate output comes in 6.5th second, which is the minimum possible time. The algorithm operates with a speed of 2 MIPS and with a memory of 18 KB. So the proposed method can be integrated to any low cost real-time embedded platforms to accurately measure the heart rate.
关键词： PPG,fast Fourier transform,heart rate,smoothing,frequency domain,FFT,photoplethysmography,decimation
更新于2025-09-23 15:23:52
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Influence of Heart Rate and Innovative Motion-Correction Algorithm on Coronary Artery Image Quality and Measurement Accuracy Using 256-Detector Row Computed Tomography Scanner: Phantom Study
摘要： Objective: To investigate the efficacy of motion-correction algorithm (MCA) in improving coronary artery image quality and measurement accuracy using an anthropomorphic dynamic heart phantom and 256-detector row computed tomography (CT) scanner. Materials and Methods: An anthropomorphic dynamic heart phantom was scanned under a static condition and under heart rate (HR) simulation of 50–120 beats per minute (bpm), and the obtained images were reconstructed using conventional algorithm (CA) and MCA. We compared the subjective image quality of coronary arteries using a four-point scale (1, excellent; 2, good; 3, fair; 4, poor) and measurement accuracy using measurement errors of the minimal luminal diameter (MLD) and minimal luminal area (MLA). Results: Compared with CA, MCA significantly improved the subjective image quality at HRs of 110 bpm (1.3 ± 0.3 vs. 1.9 ± 0.8, p = 0.003) and 120 bpm (1.7 ± 0.7 vs. 2.3 ± 0.6, p = 0.006). The measurement error of MLD significantly decreased on using MCA at 110 bpm (11.7 ± 5.9% vs. 18.4 ± 9.4%, p = 0.013) and 120 bpm (10.0 ± 7.3% vs. 25.0 ± 16.5%, p = 0.013). The measurement error of the MLA was also reduced using MCA at 110 bpm (19.2 ± 28.1% vs. 26.4 ± 21.6%, p = 0.028) and 120 bpm (17.9 ± 17.7% vs. 34.8 ± 19.6%, p = 0.018). Conclusion: Motion-correction algorithm can improve the coronary artery image quality and measurement accuracy at a high HR using an anthropomorphic dynamic heart phantom and 256-detector row CT scanner.
关键词： Heart rate,Tomography,X-ray computed,Coronary vessels,Phantoms,Imaging,Motion-correction algorithm
更新于2025-09-23 15:23:52
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Second-generation motion correction algorithm improves diagnostic accuracy of single-beat coronary CT angiography in patients with increased heart rate
摘要： Objective To assess the effect of a second-generation motion correction algorithm on the diagnostic accuracy of coronary computed tomography angiography (CCTA) using a 256-detector row CT in patients with increased heart rates. Methods Eighty-one consecutive symptomatic cardiac patients with increased heart rates (≥ 75 beats per min) were enrolled. All patients underwent CCTA and invasive coronary angiography (ICA). CCTA was performed with a 256-detector row CT using prospectively ECG-triggered single-beat protocol. Images were reconstructed using standard (STD) algorithm, first-generation intra-cycle motion correction (MC1) algorithm, and second-generation intra-cycle motion correction (MC2) algorithm. The image quality of coronary artery segments was assessed by two experienced radiologists using a 4-point scale (1: non-diagnostic and 4: excellent), according to the 18-segment model. Diagnostic performance for segments with significant lumen stenosis (≥ 50%) was compared between STD, MC1, and MC2 by using ICA as the reference standard. Results The mean effective dose of CCTA was 1.0 mSv. On per-segment level, the overall image quality score and interpretability were improved to 3.56 ± 0.63 and 99.2% due to the use of MC2, as compared to 2.81 ± 0.85 and 92.5% with STD and 3.21 ± 0.79 and 97.2% with MC1. On per-segment level, compared to STD and MC1, MC2 improved the sensitivity (92.2% vs. 79.2%, 80.7%), specificity (97.8% vs. 82.1%, 90.8%), positive predictive value (89.9% vs. 48.4%, 65.1%), negative predictive value (98.3% vs. 94.9%, 95.7%), and diagnostic accuracy (96.8% vs. 81.5%, 89.0%). Conclusion A second-generation intra-cycle motion correction algorithm for single-beat CCTA significantly improves image quality and diagnostic accuracy in patients with increased heart rate.
关键词： Coronary angiography,Heart rate,Tomography, X-ray computed,Coronary vessels,Motion
更新于2025-09-23 15:23:52
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Remote Heart Rate Measurement from RGB-NIR Video Based on Spatial and Spectral Face Patch Selection
摘要： In this paper, we propose a novel heart rate (HR) estimation method using simultaneously recorded RGB and near-infrared (NIR) face videos. The key idea of our method is to automatically select suitable face patches for HR estimation in both spatial and spectral domains. The spatial and spectral face patch selection enables us to robustly estimate HR under various situations, including scenes under which existing RGB camera-based methods fail to accurately estimate HR. For a challenging scene in low light and with light fluctuations, our method can successfully estimate HR for all 20 subjects (±3 beats per minute), while the RGB camera-based methods succeed only for 25% of the subjects.
关键词： spectral domain,remote sensing,spatial domain,face patch selection,heart rate estimation,RGB-NIR video
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE XXV International Conference on Electronics, Electrical Engineering and Computing (INTERCON) - Lima (2018.8.8-2018.8.10)] 2018 IEEE XXV International Conference on Electronics, Electrical Engineering and Computing (INTERCON) - An Algorithm for The Quantification of Lipids, Collagen and Muscle Cells in Coronary Arteries Based on Digital Image Processing
摘要： The present study presents a method to quantify lipids, collagen and muscle cells, to help diagnose atherosclerosis using digital image processing techniques. The relative concentrations of these three indicators are crucial in diagnosing atherosclerosis in patients. Digital image processing techniques such as object detection, color enhancement, and shape and texture analysis were used to quantify cells. The objective of the algorithm is to analyze high definition images of coronary arteries and to provide an objective outcome on the atherosclerotic tissue stage. The algorithm presented outstanding results and an innovative method to diagnose atherosclerosis when compared to existing procedures in the literature.
关键词： coronary heart tissue,lipids,quantification,muscle cells,Digital Image Processing,collagen
更新于2025-09-23 15:23:52
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[IEEE 2018 Innovations in Intelligent Systems and Applications (INISTA) - Thessaloniki (2018.7.3-2018.7.5)] 2018 Innovations in Intelligent Systems and Applications (INISTA) - Piezologist: A Novel Wearable Piezoelectric-based Cardiorespiratory Monitoring System
摘要： In this paper, the design, prototyping and software development of a novel wearable cardiorespiratory parameters monitoring sensor and software applications illustrated. Piezologist is an unobtrusive chest worn device. It comprises a patch-type sensor and a mobile application. The sensor utilizes piezoelectric material as the cardiorespiratory signal sensing component and MetaWearC board as the signal acquisition unit. The board also comes with Bluetooth Low Energy (BLE) support which is utilized for the raw signal transmission. The novelty aspect of the system rests on the fact that not only using a single cheap piezoelectric sheet common cardiorespiratory parameters (such as heart rate, respiration rate, and cycles) were obtained similar to previous studies but ECG waveform and blood pressure data were also extracted successfully using the same sensor. In addition, sensor packaging design and prototyping and their effect on the acquired signal strength on one hand and the package size (volume and weight) on the other hand were studied and reported. For performance validation purpose, the developed cardiorespiratory monitoring system results were validated against two commercial sensor devices namely 3-lead ECG sensor from eHealth sensor kit and Zephyr belt-type BioHarness sensor, and the results were reported herein. The validation process outcomes confirmed that the cardiorespiratory signals extracted using Piezologist conform with a heartbeat, respiratory cycle and ECG waveform obtained using the commercial sensors. Furthermore, a usability study was conducted to compare the user experience offered by Piezologist for measuring cardiorespiratory parameters against the commercially available sensors. The study highlighted the potential that Piezologist will take over the commercial available belt-type, watch-type and 3-lead ECG sensors.
关键词： biomedical signal processing,heart rate extraction,wearable sensors,Sensors,Vital signs,ECG waveform,Home healthcare,cardiorespiratory,Heartbeats,mobile healthcare,Respiration rate
更新于2025-09-23 15:22:29
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The Role of Exercise-Induced Arousal and Exposure to Blue-Enriched Lighting on Vigilance
摘要： It is currently assumed that exposure to an artificial blue-enriched light enhances human alertness and task performance, but recent research has suggested that behavioral effects are influenced by the basal state of arousal. Here, we tested whether the effect of blue-enriched lighting on vigilance performance depends on participants’ arousal level. Twenty-four participants completed four sessions (blue-enriched vs. dim light × low vs. high arousal) at 10 pm on four consecutive days, following a repeated-measures design. Participants’ arousal was manipulated parametrically through the execution of a cycling task at two intensities (low vs. moderate), and was checked by monitoring their heart rate. On each session, distal and proximal skin temperatures were recorded as a neuroergonomic index of vigilance, while participants performed a 20-min psychomotor vigilance task (PVT) under either blue-enriched light or dim light conditions. The Positive and Negative Affect Schedule (PANAS), Karolinska Sleepiness Scale (KSS), and Borg Rating of Perceived Exertion Scale (RPE) were used to measure subjective psychological state. The results showed that the exercise-induced manipulation of arousal produced robust alerting effects in most measures, while the lighting manipulation only attenuated subjective sleepiness and enhanced positive affect, but it did not influence behavior or physiology. Acute exposure to a blue-enriched light was practically ineffective when the arousal level was over baseline. The present research favored the use of acute physical exercise over acute exposure to blue-enriched lighting in order to boost humans’ levels of alertness when necessary, as in work settings where maintaining optimal attention is difficult (shift work, night-work, vigilance tasks) and necessary to prevent human error and accidents.
关键词： circadian,light,attention,heart rate,temperature,ergonomics,alertness,physical activity
更新于2025-09-23 15:22:29
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Cardiac Electrophysiological Effects of Light-Activated Chloride Channels
摘要： During the last decade, optogenetics has emerged as a paradigm-shifting technique to monitor and steer the behavior of specific cell types in excitable tissues, including the heart. Activation of cation-conducting channelrhodopsins (ChR) leads to membrane depolarization, allowing one to effectively trigger action potentials (AP) in cardiomyocytes. In contrast, the quest for optogenetic tools for hyperpolarization-induced inhibition of AP generation has remained challenging. The green-light activated ChR from Guillardia theta (GtACR1) mediates Cl?-driven photocurrents that have been shown to silence AP generation in different types of neurons. It has been suggested, therefore, to be a suitable tool for inhibition of cardiomyocyte activity. Using single-cell electrophysiological recordings and contraction tracking, as well as intracellular microelectrode recordings and in vivo optical recordings of whole hearts, we find that GtACR1 activation by prolonged illumination arrests cardiac cells in a depolarized state, thus inhibiting re-excitation. In line with this, GtACR1 activation by transient light pulses elicits AP in rabbit isolated cardiomyocytes and in spontaneously beating intact hearts of zebrafish. Our results show that GtACR1 inhibition of AP generation is caused by cell depolarization. While this does not address the need for optogenetic silencing through physiological means (i.e., hyperpolarization), GtACR1 is a potentially attractive tool for activating cardiomyocytes by transient light-induced depolarization.
关键词： heart,action potential,zebrafish,optogenetics,GtACR1,natural anion channelrhodopsin
更新于2025-09-23 15:22:29