Abstract
BackgroundThe aim of this study was to compare beat frequency measurements of ependymal cilia made by digital high speed imaging to those obtained using the photomultiplier and modified photodiode techniques. Using high speed video analysis the relationship of the power and recover strokes was also determined.MethodsCiliated strips of ependyma attached to slices from the brain of Wistar rats were incubated at 30°C and observed using a ×50 water immersion lens. Ciliary beat frequency was measured using each of the three techniques: the high speed video, photodiode and photomultiplier. Readings were repeated after 30 minutes incubation at 37°C. Ependymal cilia were observed in slow motion and the precise movement of cilia during the recovery stroke relative to the path travelled during the power stroke was measured.ResultsThe mean (95% confidence intervals) beat frequencies determined by the high speed video, photomultiplier and photodiode at 30°C were 27.7 (26.6 to 28.8), 25.5 (24.4 to 26.6) and 20.8 (20.4 to 21.3) Hz, respectively. The mean (95% confidence intervals) beat frequencies determined by the high speed video, photomultiplier and photodiode at 37°C were 36.4 (34 to 39.5), 38.4 (36.8 to 39.9) and 18.8 (16.9 to 20.5) Hz. The inter and intra observer reliability for measurement of ciliary beat frequency was 3.8% and 1%, respectively. Ependymal cilia were observed to move in a planar fashion during the power and recovery strokes with a maximum deviation to the right of the midline of 12.1(11.8 to 13.0)° during the power stroke and 12.6(11.6 to 13.6)° to the left of the midline during the recovery stroke.ConclusionThe photodiode technique greatly underestimates ciliary beat frequency and should not be used to measure ependymal ciliary beat frequency at the temperatures studied. Ciliary beat frequency from the high speed video and photomultiplier techniques cannot be used interchangeably. Ependymal cilia had minimal deviation to the right side during their power stroke and to the left during the recovery stroke.
Highlights
The aim of this study was to compare beat frequency measurements of ependymal cilia made by digital high speed imaging to those obtained using the photomultiplier and modified photodiode techniques
Abnormalities of ependymal ciliary function due to genetic defects seen in primary ciliary dyskinesia or secondary to infection or toxic insults may result in hydrocephalus [5,6,7,8,9,10,11,12]
The primary aim of this study was to compare the measurement of ependymal ciliary beat frequency made by the photodiode, photomultiplier and digital high speed video methods
Summary
The aim of this study was to compare beat frequency measurements of ependymal cilia made by digital high speed imaging to those obtained using the photomultiplier and modified photodiode techniques. Ependymal cells have approximately forty rapidly beating cilia that Their precise role is unclear but it has been suggested that they may have a role in host defence keeping pathogens and debris away from the surface of the brain and by rapidly moving CSF immediately adjacent to the ependymal surface to facilitate diffusion of toxins from the brain into the CSF. Recent data support their role in creating concentration gradients to facilitate neuroblast migration [4]. Abnormalities of ependymal ciliary function due to genetic defects seen in primary ciliary dyskinesia or secondary to infection or toxic insults may result in hydrocephalus [5,6,7,8,9,10,11,12].
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