A Method for Markerless Tracking of the Strain Distribution of Actively Contracting Cardiac Muscle Preparations

Cheuk, Ming L.; Tang, Emily J. Lam Po; HajiRassouliha, Amir; Han, June‐Chiew; Nielsen, Poul M. F.; Taberner, Andrew J.

doi:10.1007/s11340-020-00646-w

Cited by 6 publications

(5 citation statements)

References 29 publications

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“…Isometric force control in this study was achieved by maintaining muscle length rather than sarcomere length. We did not measure internal shortening explicitly during this study, though a previous study indicates that sarcomere length may not be homogenous during fixed-end contraction at L 100 ( 28 ). To control the muscle length such that the sarcomere length in the central region is fixed would require stretching the sarcomeres at each end of the trabecula.…”

Section: Discussionmentioning

confidence: 99%

“…Following the experiment, the bright-field and fluorescence images were analyzed using a weighted averaging technique. First, the bright-field images from each window were stitched together and a central point in the most upstream imaging window was tracked using a subpixel registration algorithm ( 28 ). A measured Gaussian function of the regional fluorescence signal intensity was aligned with each bright-field imaging window.…”

Section: Methodsmentioning

confidence: 99%

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Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload

Dowrick

Tran

Garrett

et al. 2022

Journal of Applied Physiology

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Preload and afterload dictate the dynamics of the cyclical work-loop contraction that the heart undergoes in vivo. Cellular Ca2+ dynamics drive contraction, but the effects of afterload alone on the Ca2+ transient are inconclusive. No study has investigated whether the putative afterload dependence of the Ca2+ transient is preload dependent. This study is designed to provide the first insight into the Ca2+ handling of cardiac trabeculae undergoing work-loop contractions, with the aim to examine whether the conflicting afterload dependency of the Ca2+ transient can be accounted for by considering preload under isometric and physiological work‑loop contractions. Thus, we subjected ex vivo rat right-ventricular trabeculae, loaded with the fluorescent dye Fura‑2, to work‑loop contractions over a wide range of afterloads at two preloads while measuring stress, length changes, and Ca2+ transients. Work‑loop control was implemented with a real-time Windkessel model to mimic the contraction patterns of the heart in vivo. We extracted a range of metrics from the measured steady‑state twitch stress and Ca2+ transients, including the amplitudes, time courses, rates of rise, and integrals. Results show that parameters of stress were afterload and preload dependent. In contrast, the parameters associated with Ca2+ transients displayed a mixed dependence on afterload and preload. Most notably, its time course was afterload-dependent - an effect augmented at the greater preload. This study reveals that the afterload dependence of cardiac Ca2+ transients is modulated by preload, which brings the study of Ca2+ transients during isometric contractions into question when aiming to understand physiological Ca2+ handling.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload

Dowrick

Tran

Garrett

et al. 2022

Journal of Applied Physiology

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“…One way to monitor deformation in native tissue is based on the implantation of high-density beads that can be tracked echocardiographically (Ashikaga et al 2004). Other techniques allow strain tracking on and within cardiac tissue by imaging intrinsic tissue features, using modalities such as brightfield microscopy, confocal imaging, speckle tracking ultrasound, magnetic resonance imaging (MRI, Odening et al 2013;Brado et al 2017;Cheuk et al 2021) or optical coherence tomography (Cheuk et al 2017).…”

Section: Shear Rheometrymentioning

confidence: 99%

Passive myocardial mechanical properties: meaning, measurement, models

et al. 2021

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Passive mechanical tissue properties are major determinants of myocardial contraction and relaxation and, thus, shape cardiac function. Tightly regulated, dynamically adapting throughout life, and affecting a host of cellular functions, passive tissue mechanics also contribute to cardiac dysfunction. Development of treatments and early identification of diseases requires better spatio-temporal characterisation of tissue mechanical properties and their underlying mechanisms. With this understanding, key regulators may be identified, providing pathways with potential to control and limit pathological development. Methodologies and models used to assess and mimic tissue mechanical properties are diverse, and available data are in part mutually contradictory. In this review, we define important concepts useful for characterising passive mechanical tissue properties, and compare a variety of in vitro and in vivo techniques that allow one to assess tissue mechanics. We give definitions of key terms, and summarise insight into determinants of myocardial stiffness in situ. We then provide an overview of common experimental models utilised to assess the role of environmental stiffness and composition, and its effects on cardiac cell and tissue function. Finally, promising future directions are outlined.

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“…Similarly, the SEI is also a relationship with the capita gross domestic product (GDP), and it increased to 8.6% between 1979 and 2014. The improvement in ordinary people’s living conditions remains modest, and the wealth gap between the affluent and the poor is expanding ( Cheuk et al, 2021 ). Only one percent of Chinese families had more than one-third of total household wealth and education in 2014, while the poorest one-fourth owned less than 2% ( Xie and Jin, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Exploring socioeconomic inequality in educational management information system: An ethnographic study of China rural area students

2022

Front. Psychol.

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There is currently enough systematic literature presents about socioeconomic inequalities across different disciplines. However, this study relates socioeconomic inequality (SEI) to rural students educational management information systems (EMIS) in different schools in China. The dynamic force of information technology could not be constrained in the modern techno-based world. Similarly, the study was qualitative and ethnographic. Data were collected through an interview guide and analyzed with thematic scientific analysis. Ten male and ten female students were interviewed based on data saturation point. The purposive sampling technique was used for the rural school and students’ selection. This study summarizes the findings and brings together in-depth emic and etic findings based on new Marxist conflict theory, exploitation, and domination power lens. The study found that SEI creates disparities among EMIS. Household income inequality has influenced on educational achievements of rural areas’ students. Gender-based SEI was not present among students. Family wealth and SES-based exploitation are present regarding EMIS among male and female students. Household wealth is significant for the EMIS. The study put forward a recommendation to the policymakers that exploitation could be overcome among students if the government provides equal opportunities for access to the EMIS.

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A Method for Markerless Tracking of the Strain Distribution of Actively Contracting Cardiac Muscle Preparations

Cited by 6 publications

References 29 publications

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload

Passive myocardial mechanical properties: meaning, measurement, models

Exploring socioeconomic inequality in educational management information system: An ethnographic study of China rural area students

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A Method for Markerless Tracking of the Strain Distribution of Actively Contracting Cardiac Muscle Preparations

Cited by 6 publications

References 29 publications

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca2+ transients is modulated by preload

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca2+ transients is modulated by preload

Passive myocardial mechanical properties: meaning, measurement, models

Exploring socioeconomic inequality in educational management information system: An ethnographic study of China rural area students

Contact Info

Product

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Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload

Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca²⁺ transients is modulated by preload