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An Insight into Advanced Nanoparticles as Multifunctional Biomimetic Systems in Tissue Engineering
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Kusha Sharma, Abhay Tharmatt, Pooja A Chawla, Kamal Shah, Viney Chawla, Bharti Sapra, Neena Bedi
Currently, both synthetic and natural hydrogels are being used widely in cardiac TE, including poly (N-isopropyl acrylamide, poly-L-lactide, alginate, gelatine, and poly (ethylene glycol) (PEG). The native myocardium achieves heart contraction, allowing conductivity between cardiomyocytes, promoting the dissemination of the action potential. However, in traditional scaffolding materials, conductivity is limited due to the many large pores within the structures (Kamaleddin and Medicine, 2017). Different scaffolding materials have been integrated into NPs to improve the electrical conductivity and imitate the nanofibrous structures of the native myocardium ECM (Kitsara et al., 2017).
Diabetes Mellitus and Ischemic Heart Disease
Published in E.I. Sokolov, Obesity and Diabetes Mellitus, 2020
Physiological studies of cardiac activities (both under conditions of rest and under a physical load) revealed that the increase in the amplitude and force of heart contraction at any frequency thereof occurs on the background of the complete diastolic relaxation of the myocardium [12, 109]. Under conditions of a physical load, when the amplitude, force, and frequency of heart contractions increase simultaneously, this result can be achieved only by increasing the rate of the relaxation process. Experiments with animals did show this relation [388, 434]. It was proved that the rate of relaxation increases not only with a growth in the frequency, but also with a growth in the amplitude or force of contraction within the physiological range. It is this clear-cut physiological relation between the contraction and relaxation of the cardiac myocytes that preserve the diastolic pause and the stability of the contractive function of the heart under any physiological loads.
Bioelectric and Biomagnetic Signal Analysis
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
Heart-related diseases are caused due to three types of disorders: 1) electrical; 2) blood circulation and 3) structural. Often these three defects are related. For example, electrical signal problem in a heart can cause the heart-contraction problem. The heart contraction problem can result into the blood circulation problem. Electrical problem causes different types of irregular heartbeats. Irregular beats in atria can cause blood clots that can lead to brain strokes and blockages. Irregular beats in ventricles can cause sudden cardiac death (SCD). Irregular beat can also be caused due to the lack or excess of different cells, minerals and oxygen carried by blood. Low oxygen from lung can cause heart to beat faster because an adequate amount of oxygen needs to be supplied to the cells. The blood-circulation problem is also caused when cholesterol or blood-clot blocks the blood flow.
On Terms within Organizational Behavior Management
Published in Journal of Organizational Behavior Management, 2023
Douglas A. Johnson, Rachael Ferguson
Another important nuance of stimuli relates to sources of change – changes in the environment can be internal or external to the person. Put differently, the stimulation that occurs within our bodies also count as stimuli, even if these cannot be perceived by anyone outside of the person experiencing the sensation. These include covert events such as pain, a racing heart, contraction of stomach muscles, and other physiological events. Covert verbal events (e.g., sound of one’s private dialogue, physiological sensations) also serve as stimuli and are critical to understanding many complex forms of behavior. This understanding of the private world is particularly important when interacting with verbally sophisticated individuals, which is routine within organizational settings. A willingness to include covert events is a defining feature of modern behavior analysis (Skinner, 1945), a fact often missed by critics who erroneously suggest the field excludes thoughts and feelings. However, internal events are still conceptualized as physical events; the field eschews mentalistic constructs and states (such as drives to succeed, expectancies, laziness, mental storage devices, schemas, etc.). Behavior analysis, and by extension OBM, is successful by exploring both simple and complex relationships between stimuli and responses without adding unnecessary and misleading elements.
Solanaceae glycoalkaloids: α-solanine and α-chaconine modify the cardioinhibitory activity of verapamil
Published in Pharmaceutical Biology, 2022
Szymon Chowański, Magdalena Winkiel, Monika Szymczak-Cendlak, Paweł Marciniak, Dominika Mańczak, Karolina Walkowiak-Nowicka, Marta Spochacz, Sabino A. Bufo, Laura Scrano, Zbigniew Adamski
A microdensitometric method, described previously (Marciniak et al. 2008; Chowański and Rosiński 2017; Chowański et al. 2017; Pacholska-Bogalska et al. 2018), was used to analyse the cardiotropic effects of the compounds tested. It allows the measurement of the heart contraction frequency of a semi-isolated heart in insects. Briefly, this method uses a light beam that passes through the myocardium. The density of the tissue changes temporally during the heart cycle, increasing during contraction and decreasing during relaxation. Thus, the amount of light that passes through the myocardium also changes. The intensity of the light beam transmitted through the myocardium is recorded by photodiodes and converted into an electrical signal presented as a cardiomyogram. The signal is registered and converted with LARWA software designed in our department. The experiments were conducted on a semi-isolated heart, the preparation of which is described above. A semi-isolated heart was placed in an incubation chamber and perfused with saline at a flow rate of 300 μL/min. After 5 min of preincubation, registration was started, and the signal was recorded for 22 min. During that time, the preparation was perfused with saline or various solutions of the tested compounds.
Leaflet stress quantification of porcine vs bovine surgical bioprostheses: an in vitro study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Viktória Stanová, Yves Godio Raboutet, Paul Barragan, Lionel Thollon, Philippe Pibarot, Régis Rieu
For the purpose of this study, a double activation left heart duplicator system (Tanné et al. 2010) was used. This system is able to accurately simulate the human blood circulation from the pulmonary veins to the peripheral systemic capillaries by reproducing physiological pressure and flow waveforms. A saline glycerol solution fixed at 3.8 cP at 37 °C was used to mimic blood viscosity. The simulation system includes: i) anatomically shaped, deformable silicon molds of left heart cavities, which are compressed or stretched in order to mimic left heart contraction and relaxation and ii) a glass model of the aorta that enables optimal visualization of valve leaflets. Contraction of the left ventricle and left atrium were obtained using two ViVitro piston pumps (ViVitro Inc., Victoria, Canada). Pressures in both the left ventricle and the aortic root were recorded by micro-tip pressure catheters (Millar catheter and signal conditioning unit, Millar Instruments, Houston, TX, accuracy ±0.5% maximum full scale). Transvalvular flow was measured with an electromagnetic flowmeter (Model 501, Carolina Medical Electronics Inc., East Bend, USA, accuracy ±1% maximum full scale) positioned immediately below the bioprosthesis and averaged over 100 cycles. Both pump activation and signal acquisition (Figure 2) were controlled with LabVIEW8.2 (National Instruments, TX, USA) to achieve physiological flow as recommended in the ISO standards for heart valve testing in normal flow conditions (ISO 5840-part 3).