forced oscillations
Dotaz
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European respiratory review, ISSN 0905-9180 vol. 4, rev. no. 19, February 1994
116-237 s. : il., tab. ; 28 cm
- MeSH
- fyziologie dýchací soustavy MeSH
- mechanika dýchání MeSH
- pletyzmografie impedanční MeSH
- plicní ventilace MeSH
- respirační funkční testy využití MeSH
- Publikační typ
- sborníky MeSH
- Konspekt
- Patologie. Klinická medicína
- NLK Obory
- pneumologie a ftizeologie
The cardiac excitation-contraction coupling is the cellular process through which the heart absolves its blood pumping function, and it is directly affected when cardiac pathologies occur. Cardiomyocytes are the functional units in which this complex biomolecular process takes place: they can be represented as a two-stage electro-chemo and chemo-mechanical transducer, along which each stage can be probed and monitored via appropriate micro/nanotechnology-based tools. Atomic force microscopy (AFM), with its unique nanoresolved force sensitivity and versatile modes of extracting sample properties, can represent a key instrument to study time-dependent heart mechanics and topography at the single cell level. In this work, we show how the integrative possibilities of AFM allowed us to implement an in vitro system which can monitor cardiac electrophysiology, intracellular calcium dynamics, and single cell mechanics. We believe this single cell-sensitive and integrated system will unlock improved, fast, and reliable cardiac in vitro tests in the future.
- MeSH
- analýza dat MeSH
- elektrofyziologické jevy * MeSH
- kardiomyocyty cytologie fyziologie MeSH
- mechanické jevy * MeSH
- mikroskopie atomárních sil * přístrojové vybavení metody MeSH
- molekulární zobrazování MeSH
- spřažení excitace a kontrakce * MeSH
- vápníková signalizace MeSH
- Publikační typ
- časopisecké články MeSH
Higher harmonic contributions in the movement of an oscillating atomic force microscopy (AFM) cantilever are generated by nonlinear tip-sample interactions, yielding additional information on structure and physical properties such as sample stiffness. Higher harmonic amplitudes are strongly enhanced in liquid compared to the operation in air, and were previously reported to result in better structural resolution in highly organized lattices of proteins in bacterial S-layers and viral capsids [J. Preiner, J. Tang, V. Pastushenko, P. Hinterdorfer, Phys. Rev. Lett. 99 (2007) 046102]. We compared first and second harmonics AFM imaging of live and fixed human lung epithelial cells, and microvascular endothelial cells from mouse myocardium (MyEnd). Phase-distance cycles revealed that the second harmonic phase is 8 times more sensitive than the first harmonic phase with respect to variations in the distance between cantilever and sample surface. Frequency spectra were acquired at different positions on living and fixed cells with second harmonic amplitude values correlating with the sample stiffness. We conclude that variations in sample stiffness and corresponding changes in the cantilever-sample distance, latter effect caused by the finite feedback response, result in second harmonic images with improved contrast and information that is not attainable in the fundamental frequency of an oscillating cantilever.
- MeSH
- endoteliální buňky ultrastruktura MeSH
- epitelové buňky MeSH
- eukaryotické buňky MeSH
- lidé MeSH
- mikroskopie atomárních sil metody MeSH
- myokard cytologie MeSH
- myši MeSH
- plíce cytologie MeSH
- pružnost MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Impulzní oscilometrie (IOS) je citlivá a neinvazivní metoda pro měření plicních funkcí. Patří mezi tzv. FOT metody - metody nucených oscilací (FOT- forced oscillation technique). FOT využívá nízkoamplitudové kmity překrývající normální dýchání (3). Proti konvenčním metodám funkčního vyšetřování má tu výhodu, že nevyžaduje provádění usilovných dechových manévrů.
Impulse oscillometry (IOS) is a sensitive and noninvasive method for the measurement of lung function. It is one of the so-called forced oscillation techniques (FOTs). FOTs use low amplitude oscillations superimposed on normal breathing. Unlike the conventional lung function tests, they have the advantage of not requiring strenuous respiratory memeuvers.
- MeSH
- bronchiální astma diagnóza MeSH
- chronická obstrukční plicní nemoc diagnóza MeSH
- dechové testy přístrojové vybavení MeSH
- diagnostické techniky dýchacího ústrojí * MeSH
- lidé MeSH
- nemoci dýchací soustavy diagnóza MeSH
- oscilometrie * metody MeSH
- plicní nemoci diagnóza MeSH
- respirační funkční testy * metody MeSH
- Check Tag
- lidé MeSH
Calcium ions act like ubiquitous second messengers in a wide amount of cellular processes. In cardiac myocytes, Ca2+ handling regulates the mechanical contraction necessary to the heart pump function. The field of intracellular and intercellular Ca2+ handling, employing in vitro models of cardiomyocytes, has become a cornerstone to understand the role and adaptation of calcium signalling in healthy and diseased hearts. Comprehensive in vitro systems and cell-based biosensors are powerful tools to enrich and speed up cardiac phenotypic and drug response evaluation. We have implemented a combined setup to measure contractility and calcium waves in human embryonic stem cells-derived cardiomyocyte 3D clusters, obtained from embryoid body differentiation. A combination of atomic force microscopy to monitor cardiac contractility, and sensitive fast scientific complementary metal-oxide-semiconductor camera for epifluorescence video recording, provided correlated signals in real time. To speed up the integrated data processing, we tested several post-processing algorithms, to improve the automatic detection of relevant functional parameters. The validation of our proposed method was assessed by caffeine stimulation (10mM) and detection/characterization of the induced cardiac response. We successfully report the first simultaneous recording of cardiac contractility and calcium waves on the described cardiac 3D models. The drug stimulation confirmed the automatic detection capabilities of the used algorithms, measuring expected physiological response, such as elongation of contraction time and Ca2+ cytosolic persistence, increased calcium basal fluorescence, and transient peaks. These results contribute to the implementation of novel, integrated, high-information, and reliable experimental systems for cardiac models and drug evaluation.
- MeSH
- biofyzika metody MeSH
- kardiomyocyty metabolismus MeSH
- lidé MeSH
- vápník metabolismus MeSH
- vápníková signalizace fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Understanding interactions of calcium with lipid membranes at the molecular level is of great importance in light of their involvement in calcium signaling, association of proteins with cellular membranes, and membrane fusion. We quantify these interactions in detail by employing a combination of spectroscopic methods with atomistic molecular dynamics simulations. Namely, time-resolved fluorescent spectroscopy of lipid vesicles and vibrational sum frequency spectroscopy of lipid monolayers are used to characterize local binding sites of calcium in zwitterionic and anionic model lipid assemblies, while dynamic light scattering and zeta potential measurements are employed for macroscopic characterization of lipid vesicles in calcium-containing environments. To gain additional atomic-level information, the experiments are complemented by molecular simulations that utilize an accurate force field for calcium ions with scaled charges effectively accounting for electronic polarization effects. We demonstrate that lipid membranes have substantial calcium-binding capacity, with several types of binding sites present. Significantly, the binding mode depends on calcium concentration with important implications for calcium buffering, synaptic plasticity, and protein-membrane association.
- MeSH
- buněčná membrána metabolismus MeSH
- fosfolipidy chemie metabolismus MeSH
- lipidové dvojvrstvy chemie metabolismus MeSH
- liposomy chemie metabolismus MeSH
- molekulární modely MeSH
- simulace molekulární dynamiky MeSH
- vápník metabolismus MeSH
- vápníková signalizace MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Explaining why fluctuations in abundances of spatially disjunct populations often are correlated through time is a major goal of population ecologists. We address two hypotheses receiving little to no testing in wild populations: (i) that population cycling facilitates synchronization given weak coupling among populations, and (ii) that the ability of periodic external forces to synchronize oscillating populations is a function of the mismatch in timescales (detuning) between the force and the population. Here, we apply new analytical methods to field survey data on gypsy moth outbreaks. We report that at timescales associated with gypsy moth outbreaks, spatial synchrony increased with population periodicity via phase locking. The extent to which synchrony in temperature and precipitation influenced population synchrony was associated with the degree of mismatch in dominant timescales of oscillation. Our study provides new empirical methods and rare empirical evidence that population cycling and low detuning can promote population spatial synchrony.
- MeSH
- biologické modely MeSH
- časové faktory MeSH
- déšť * MeSH
- larva růst a vývoj fyziologie MeSH
- můry růst a vývoj fyziologie MeSH
- populační dynamika MeSH
- teplota * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Geografické názvy
- Spojené státy americké MeSH
Impulzní oscilometrie (IOS) patří mezi novější metody vyšetřování plicních funkcí. Princip je znám již 20 let, ale zavedení do medicínské praxe umožnil až vývoj počítačové techniky. V rámci klasifikace metod funkčního plicního vyšetřování je IOS zařazována mezi tzv. FOT (forced oscillation technique) (1, 2) a v poslední době se dostává i do povědomí světové (3 - 8) i naší odborné veřejnosti (9, 10). IOS je neinvazivní, senzitivní a rychlá metoda měření rezistence, respektive impedance v dýchacích cestách. Zásadní rozdíl od konvenčních metod vyšetření plicních funkcí (spirometrie a body test) spočívá v rychlosti vyšetření, minimálních nárocích na spolupráci, a zejména v měření za podmínek klidového dýchání (odpadá nefyziologický manévr usilovného výdechu).
The Impulse Oscillometry (IOS) is regarded as quite recent method of lung functions measurement, despite its principle well known over 20 years, but available for clinical use due to the advanced computer technology. Framed in a classification of methods of measurements, the IOS is regarded as FOT (Forced Oscillation Technique) (1, 2) and recently recognized as a noninvasive, sensitive and quick method for measurement of impedance, including resistance, worldwide (3-8) and local (9, 10) specialists. The basic difference (and advantage) between IOS on one hand and conventional methods (spirometry, bodyplethysmography) on the other hand is a short duration of measurement, minimum of patients cooperation, and last but not least use of only tidal breathing, with no need for unnatural forced exspiration during measurement.
