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Optical investigations of mucociliary transport: Synchronisation of ciliary beat

English title Optical investigations of mucociliary transport: Synchronisation of ciliary beat
Applicant Ricka Jaroslav
Number 109350
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Other disciplines of Physics
Start/End 01.01.2006 - 31.08.2008
Approved amount 143'566.00
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Keywords (4)

biomedical photonics; ciliary beat; synchronisation; mucociliary transport

Lay Summary (English)

Lead
Lay summary
Mucociliary transport is the primary defense mechanism of the lung:Inhaled particles and bacteria are entrapped in the visco-elastic mucus layer covering the epithelial surfaces, and the mucus carpet is continuously propelled towards pharynx by coordinated action of beating cilia. Cilia are about 10 micrometer long and 250 nanometer thin extracellular organelles that cover the upper airways as a dense lawn (about 5 cilia per square micrometer). Driven by molecular motors fueled by ATP, the cilia oscillate with a frequency of 15-30Hz. It is obvious that in order to achieve efficient directed transport, the ciliary motion must be, at least locally, coordinated. Indeed, ciliated surfaces exhibit coordinated beat patterns resulting from a well defined shift in the beat phase between individual cilia, the so-called "metachronal waves". The principles of this coordination and its relation to the function of the mucociliary escalator are still purely understood, chiefly because of the difficulty of the observation in situ, under the mucus-air interface.

The present project is a part of our research aimed at improved understanding of the mucociliary coordination and function, focusing thereby on optical functional imaging and advanced image processing methods. One branch of our research is application oriented, responding to demands for new diagnostic techniques: In collaboration with Storz Endokope GmbH we are developing an endoscopic probe for the determination of the ciliary oscillation frequency in vivo, in the nose or trachea of patients suffering from respiratory diseases. The second branch of our research is oriented towards fundamental understanding. Recently we completed a comprehensive study of mucociliary phenomena in excised tracheae of mammals and birds by high-speed digital reflection contrast microscopy. The simultaneously extracted data include not only ciliary beat frequency and its surface distribution, but also space-time structure of the mucociliary wave field, wave velocity and mucus transport velocity.Furthermore we analyze the space and time evolution of the phase of the mucociliary oscillations; this is the most direct way to visualize the coordination of the cilia. In particular this analysis indicates that the synchronization is restricted to patches with varying directions of wave propagation, but the transport direction is strongly correlated with the mean direction of waves. Thus, our findings suggest that current textbook model of the relation between the transport and the space-time structure of the metachronal waves may need revision (antiplectic versus symplectic metachronism). The present sub-project is aimed at the metachronal phenomena on small scale, i.e. within groups of beating cilia on individual ciliated epithelial cells. Currently we are implementing a new epi-dark-field illumination scheme based on high power LED light source.The technique should allow simultaneous observation of the modulation of the mucus-air interface, tracking of nano-particles embedded in the mucus and the detection of the ciliary motions on cells beneath the mucus layer.
Direct link to Lay Summary Last update: 21.02.2013

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