Robust estimation of the motile cilia beating frequency (original) (raw)
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Journal of Cerebral Blood Flow & Metabolism, 1999
To test the hypothesis that brain oxidative metabo lism is significantly increased upon adequate stimulation, we varied the presentation of a visual stimulus to determine the frequency at which the metabolic response would be at maxi mum, The authors measured regional CMRo in 12 healthy normal volunteers with the ECAT EXACT HR� (CTIISiemens, Knoxville, TN, U,S,A,) three-dimensional whole-body positron emission tomograph (PET). In seven successive activating con ditions, subjects viewed a yellow-blue annular checkerboard reversing its contrast at frequencies of 0, 1,4,8, 16,32, and 50
A Novel Approach for the Automatic Estimation of the Ciliated Cell Beating Frequency
Electronics, 2020
The qualitative and quantitative evaluation of nasal epithelial cells is interesting in chronic infectious and inflammatory pathologies of the nose and sinuses. Among the cells of the population of the nasal mucosa, ciliated cells are particularly important. In fact, the observation of these cells is essential to investigate primary ciliary dyskinesia, a rare and severe disease associated with other serious diseases such as respiratory diseases, situs inversus, heart disease, and male infertility. Biopsy or brushing of the ciliary mucosa and assessment of ciliary function through measurements of the Ciliary Beating Frequency (CBF) are usually required to facilitate diagnosis. Therefore, low-cost and easy-to-use technologies devoted to measuring the ciliary beating frequency are desirable. We have considered related works in this field and noticed that up to date an actually usable system is not available to measure and monitor CBF. Moreover, performing this operation manually is pra...
The use of biophysical approaches to understand ciliary beating
Biochemical Society Transactions, 2020
Motile cilia are a striking example of the functional cellular organelle, conserved across all the eukaryotic species. Motile cilia allow the swimming of cells and small organisms and transport of liquids across epithelial tissues. Whilst the molecular structure is now very well understood, the dynamics of cilia is not well established either at the single cilium level nor at the level of collective beating. Indeed, a full understanding of this requires connecting together behaviour across various lengthscales, from the molecular to the organelle, then at the cellular level and up to the tissue scale. Aside from the fundamental interest in this system, understanding beating is important to elucidate aspects of embryonic development and a variety of health conditions from fertility to genetic and infectious diseases of the airways.
The Journal of comparative neurology, 2015
The discovery of the 'glymphatic' pathway has shed new light on the cerebrospinal (CSF)brain interstitial fluid (ISF) exchange process (Iliff et al., 2012). In new anatomically defined terms, the glymphatic pathway now represents a brain-wide pathway where CSF flows through the brain and spinal cord parenchyma and exchanges with ISF from periarterial to perivenous spaces in a route interconnected by aquaporin 4 water channels present on glial cells (Iliff et al., 2012). The new concept of the glymphatic pathway has evolved from the older concept of bulk flow of ISF from brain parenchyma to the ventricular CSF referred to as the "ependymal pathway" (Brightman, 1965a,b). The glymphatic pathway is important for detoxification of the brain (and spinal cord), a cleaning process that appears to be driven by adrenergic tone (Xie et al., 2013), arterial pulsatility (Iliff et al., 2013b), level of arousal (Xie et al., 2013), and aging (Kress et al., 2014). For decades, brain pulsations have been observed directly during neurosurgical procedures. Pulsation of the CSF was first qualitatively described in vivo using fluoroscopy (Du Boulay, 1966) and then validated using non-invasively using magnetic resonance imaging (MRI) (Sherman and Citrin, 1986; Sherman et al., 1986). A comprehensive review of this topic by Wagshul and coworkers was recently published (Wagshul et al., 2011). Phase-contrast MRI was later used to quantify CSF pulsation in selected parts of the ventricular CSF spaces, followed by quantitative flow visualization in the entire subarachnoid and ventricular spaces through computational flow reconstruction from phase-contrast MRI data (
American Journal of Physiology - Renal Physiology
Primary cilia have been called “the forgotten organelle” for over 20 yr. As cilia now have their own journal and several books devoted to their study, perhaps it is time to reconsider the moniker “forgotten organelle.” In fact, during the drafting of this review, 12 relevant publications have been issued; we therefore apologize in advance for any relevant work we inadvertently omitted. What purpose is yet another ciliary review? The primary goal of this review is to specifically examine the evidence for and against the hypothesized flow-sensing function of primary cilia expressed by differentiated epithelia within a kidney tubule, bringing together differing disciplines and their respective conceptual and experimental approaches. We will show that understanding the biophysics/biomechanics of primary cilia provides essential information for understanding any potential role of ciliary function in disease. We will summarize experimental and mathematical models used to characterize rena...
Cooling of Cilia Allows Functional Analysis of the Beat Pattern for Diagnostic Testing
CHEST Journal, 2011
T he human nasopharynx is frequently exposed to changing temperatures that can affect a major component of innate host defense, mucociliary clearance, which is reduced by the inhalation of cold air. 1 A reduction in ciliary beat frequency (CBF) as temperature decreases contributes to the slowing of mucociliary clearance. 2 -4 Previous research suggests that cilia stop beating at 4°C 5-7 and then do not start beating again until the temperature increases . 10°C. 5 Most of these investigators have cooled the ciliated sample and measured frequency during warming, thus overlooking important biologic processes that could occur during cooling. Furthermore, the effect of temperature on ciliary beat pattern has not been studied. Evaluation of ciliary beat pattern in addition to beat frequency is essential because it has recently been shown that cilia may maintain a normal CBF despite having a grossly abnormal beat pattern. Additionally, in certain phenotypes of primary ciliary dyskinesia (PCD), where mucociliary clearance is grossly reduced, all the patient's cilia beat in a dyskinetic fashion despite CBF being maintained at a normal level. Recent research has shown that screening with CBF measurements to determine which patients require electron microscopy to confi rm the diagnosis Background: Reports of the effect of low temperatures on ciliary beat frequency (CBF) are confl icting, and the effect on ciliary beat pattern has not been reported. We aimed to clarify this association and determine whether cooling of cilia may allow ciliary function to be assessed without the need of expensive high-speed video microscopy. Methods: Fourteen nasal brush biopsy samples were collected, and the CBF and beat pattern of undisrupted ciliated edges were evaluated. Two methods were used to strictly control changes in temperature: One enabled rapid transitory measurements during cooling and warming, and the other was used to maintain accurate low temperatures over longer periods of time. Results: A sigmoid relationship between CBF and temperature was observed. CBF decreased with cooling and increased with warming. Ciliary function was unaffected by the direction of temperature change and was maintained down to 2°C. The percentage of dyskinetic cilia observed at 2°C or 4°C was unchanged from that at 37°C. Conclusions: Contrary to previous research, our data show that cilia continue to beat with a normal pattern at temperatures as low as 2°C. Slowing of cilia by cooling may allow detailed analysis of ciliary beat pattern without the need of expensive high-speed video microscopy.
Acta Physiologica Scandinavica, 1997
In brain cortex all capillaries are perfused with plasma at anyone time while the flow of blood cells is heterogenous. Increased blood flow is associated with increased number of moving erythrocytes in the microcirculation, while capillary recruitment in its classical anatomical sense appears not to exist in the brain. Modulation of the concentration of flowing erythrocytes may influence the oxygen supply to the tissue. Therefore, we examined the possibility that laser-Doppler flowmetry (LDF) could be used to quantify changes in the microvascular concentration of moving blood cells (CMBC) and blood cell velocity (< v >) by comparing LDF measurements with electromagnetic flow measurements in vitro, and confocal laser-scanning microscopy in vivo in the brain of anaesthetized male Wistar rats. In vitro measurements showed that CMBC was affected by changes in haematocrit, while < v > correlated almost linearly with blood cell velocity measured electromagnetically within a relevant physiological range. In vivo studies during hypercapnia (PaCO 2 from 39 4 to 66 5 mmHg) with confocal laser scanning microscopy disclosed a 39 10% increase of cortical capillary erythrocytes, while CMBC measured with LDF increased by 37 5%. Erythrocyte¯ow velocity in brain cortex capillaries increased by 65 17% with confocal microscopy as compared to 72 8% with LDF. Local electrical stimulation of cerebellar cortex, and application of adenosine or sodium-nitroprusside, increased CMBC and < v > simultaneously, while during hypercapnia the < v > increase preceded the CMBC increase by 30 s. The CMBC rise rapidly reached a steady state in response to all types of stimulation, while < v > continued to increase during the major part, or the entire stimulation period. In conclusion, our data support the hypothesis that LDF may be useful for haemodynamic studies of brain microcirculation.
Frequency encoding in renal blood flow regulation
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2005
With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation of the myogenic oscillation by TGF. Analysis by wavelet transforms of single-nephron blood flow confirms that both amplitude and frequency of the myogenic oscillation are modulated by TGF. We developed a double-wavelet transform technique to estimate modulation frequency. Median value of the ratio of modulation frequency to TGF frequency in measurements from 10 rats was 0.95 for amplitude modulation and 0.97 for frequency modulation, a result consistent with TGF as the modulating signal. The simulation predicted that the modulation was regular, while the experimental data showed much greater variability from one TGF cycle to the next. We used a blood pressure signal recorded by telemetry from a...