Direct measurement of directional disorder for ciliary metachronal wave

Abstract

Abstract-The interrelationship of cilia and the directional disorder of ciliary metachronal wave were analyzed using digital microscopic images. The degree of synchronization between ciliary beats was determined by the correlation factor between two different spots. Principal axes of inertia were applied to find out the uniphase directions of beating cilia. The standard deviation of wave directions in an ROI was defined as a measure of ciliary wave disorder (CWD). The pooled mean of CWD was 22.9+/-8.73° in ROIs of 8 µ m× 8µ m and 25.4+/-6.46° in 32µ m× 24µ m from the sphenoid sinus mucosa of 5 normal subjects. Our result shows that there is a considerable variation in metachronal wave directions of cilia beating on the epithelium.Keywords -Digital microscopic images, correlation map, uniphase directions of cilia, principal axis of inertia, ciliary wave disorder (CWD). I. INTRODUCTIONThe main task of mucociliary systems in the respiratory tract is to eliminate inhaled particles by the propulsion of mucus. The o verall propulsive effect depends upon the arrangement of the cilia, their metachronal relationships, as well as on the ciliary beat frequency (CBF) [1]. Some methods based on image analysis allow the determination of the CBF of a single cell or multiple ciliated cells simultaneously [2]-[4]. Disorientation of cilia leads to an impairment of mucociliary transport. To determine the coordination of ciliary beating, variations in the orientation of cilia have been previously measured by examining crosssections of the epithelium using an electron microscope [5]. It has been found that ciliary disorientation may occur secondary to inflammation caused by infection [6] and that the measured orientation of cilia may vary in normal subjects [6]-[8]. Ciliary disorientation alone can lead to the clinical syndrome of primary ciliary dyskinesia (PCD) [9]. The directions based on observations of ciliary cross-sections may differ from the metachronal wave directions of cilia beating in media. We have applied principal axis of inertia to the 2-dimensional correlation map calculated from sequential ciliary images. This method directly measures the phase relations and wave directions of multiple cilia beating in culture media. II. MATERIALS AND METHODSThe mucosa in the sphenoid sinus were collected from subjects of no respiratory diseases with informed consent. The ciliary movements were recorded using a CCD camera from an inverted microscope. A personal computer equipped with an image-grabber [IC-Comp ; Imaging Technology , Inc.] converted VCR signals into digital images with a depth of 8 bits. Under the magnification used, one pixel size equated to 0.1µm. The digitized images for each processing were acquired at 30Hz for about 4.27 seconds (128 frames). The whole field of 640 by 480 pixels was divided into equal sized blocks (spots) of 2 by 2 pixels. Gray-level values of all pixels in each spot were summed sequentially from the first frame to the last.Movements of cilia are coordinated in time and space by phase differen...

An operative framework to model mucus clearance in silico by coupling cilia motion with the liquid environment

“…It emerges from fluid mediated interactions between neighbouring cilia and increases the efficiency of mucus transport 8,9 . The wavelength for this wave has been estimated using different experimental approaches, with values ranging from 6 µm obtained from video transmission microscopy of human sphenoid sinus mucosa 10 , up to 20 µm found by DIC imaging of human bronchial mucosa 7 , and 50 µm using video reflection microscopy on several mammals 11 . Finally, the velocity of tracheal mucus transport was measured by scintigraphy and found to be 5 − 10 mm/min for healthy subjects 12,13 .…”