Ciliary Flow Research Articles

Heat transfer analysis of tangent hyperbolic nanofluid in a ciliated tube with entropy generation

In this paper, we analyze the effect of heat transfer on the flow of tangent hyperbolic nanofluid in a ciliated tube (fallopian tube where embryo in blood make the development). This study will be beneficial for the researchers and medical experts in the field of embryology. The nanoparticles are beneficial to remove the cysts from the fallopian tube where development of embryo takes place. To resolves the ciliary flow problems, medical doctors use nanoparticles (drug delivery) that may create a temperature gradient. The heat transfer helps to optimize the energy for which the entropy generation is reduced. Therefore, in this research we discuss the heat transfer effect on tangent hyperbolic nanofluid and entropy generation due to ciliary movement. The governing partial differential equations are solved by HPM and software MATHEMATICA™. Effect of viscoelastic parameter, nanoparticles, cilia length and Brinkman number on the velocity, temperature and entropy generation has been illustrated with the help of graphs. Graphical results show that thermal conductivity of fluid increases by adding nanoparticles. The entropy generation due to nanoparticles will decrease the viscosity near the tube wall and blood through tube will flow with normal pressure.

Residual time of sinusoidal metachronal ciliary flow of non-Newtonian fluid through ciliated walls: fertilization and implantation.

The monitoring of the ciliated walls in the uterine tube has supreme importance in enhancing the sperm to reach the egg (capacitation processes), and at peristaltic ciliary flow has a more favorable residual time along the canal when compared to the peristaltic flow. Based on the importance of this study, a mathematical simulation of this process has been carried out by studying the behavior of a non-Newtonian magnetized fluid with a Darcy flow model with an oscillating wall having an internal ciliated surface. The governing equation is formed with Eyring-Powell fluid (tubal fallopian fluid) without using any approximations and solved using the Adomian analysis method. Using the vorticity formula, the components of the velocity function, pressure gradient, and stream function are obtained. The influence of relevant parameters is explained through diagramming and discussion. We also analyzed the residue time effects on the flow parameters. The results indicate that peristaltic ciliary flow has a more favorable residual time along the canal when compared to peristaltic flow.

In Xenopus ependymal cilia drive embryonic CSF circulation and brain development independently of cardiac pulsatile forces

BackgroundHydrocephalus, the pathological expansion of the cerebrospinal fluid (CSF)-filled cerebral ventricles, is a common, deadly disease. In the adult, cardiac and respiratory forces are the main drivers of CSF flow within the brain ventricular system to remove waste and deliver nutrients. In contrast, the mechanics and functions of CSF circulation in the embryonic brain are poorly understood. This is primarily due to the lack of model systems and imaging technology to study these early time points. Here, we studied embryos of the vertebrate Xenopus with optical coherence tomography (OCT) imaging to investigate in vivo ventricular and neural development during the onset of CSF circulation.MethodsOptical coherence tomography (OCT), a cross-sectional imaging modality, was used to study developing Xenopus tadpole brains and to dynamically detect in vivo ventricular morphology and CSF circulation in real-time, at micrometer resolution. The effects of immobilizing cilia and cardiac ablation were investigated.ResultsIn Xenopus, using OCT imaging, we demonstrated that ventriculogenesis can be tracked throughout development until the beginning of metamorphosis. We found that during Xenopus embryogenesis, initially, CSF fills the primitive ventricular space and remains static, followed by the initiation of the cilia driven CSF circulation where ependymal cilia create a polarized CSF flow. No pulsatile flow was detected throughout these tailbud and early tadpole stages. As development progressed, despite the emergence of the choroid plexus in Xenopus, cardiac forces did not contribute to the CSF circulation, and ciliary flow remained the driver of the intercompartmental bidirectional flow as well as the near-wall flow. We finally showed that cilia driven flow is crucial for proper rostral development and regulated the spatial neural cell organization.ConclusionsOur data support a paradigm in which Xenopus embryonic ventriculogenesis and rostral brain development are critically dependent on ependymal cilia-driven CSF flow currents that are generated independently of cardiac pulsatile forces. Our work suggests that the Xenopus ventricular system forms a complex cilia-driven CSF flow network which regulates neural cell organization. This work will redirect efforts to understand the molecular regulators of embryonic CSF flow by focusing attention on motile cilia rather than other forces relevant only to the adult.

Swimming microorganisms acquire optimal efficiency with multiple cilia

Planktonic microorganisms are ubiquitous in water, and their population dynamics are essential for forecasting the behavior of global aquatic ecosystems. Their population dynamics are strongly affected by these organisms' motility, which is generated by their hair-like organelles, called cilia or flagella. However, because of the complexity of ciliary dynamics, the precise role of ciliary flow in microbial life remains unclear. Here, we have used ciliary hydrodynamics to show that ciliates acquire the optimal propulsion efficiency. We found that ciliary flow highly resists an organism's propulsion and that the swimming velocity rapidly decreases with body size, proportional to the power of minus two. Accordingly, the propulsion efficiency decreases as the cube of body length. By increasing the number of cilia, however, efficiency can be significantly improved, up to 100-fold. We found that there exists an optimal number density of cilia, which provides the maximum propulsion efficiency for all ciliates. The propulsion efficiency in this case decreases inversely proportionally to body length. Our estimated optimal density of cilia corresponds to those of actual microorganisms, including species of ciliates and microalgae, which suggests that now-existing motile ciliates and microalgae have survived by acquiring the optimal propulsion efficiency. These conclusions are helpful for better understanding the ecology of microorganisms, such as the energetic costs and benefits of multicellularity in Volvocaceae, as well as for the optimal design of artificial microswimmers.

Simulating cilia-driven mixing and transport in complex geometries

An efficient hybrid numerical method for ciliary flow is proposed, combining the boundary integral method and the method of regularized stokeslets. It is capable of simulating ciliary flows and particle transport in complex 2D confined geometries. The effects of metachronal waves and geometries on ciliary transport as well as fluid mixing are analyzed. Size effect of submerged rigid particles inside the confined geometries is also studied.

Ciliary vortex flows and oxygen dynamics in the coral boundary layer

The exchange of metabolites between environment and coral tissue depends on the flux across the diffusive boundary layer (DBL) surrounding the tissue. Cilia covering the coral tissue have been shown to create vortices that enhance mixing in the DBL in stagnant water. To study the role of cilia under simulated ambient currents, we designed a new light-sheet microscopy based flow chamber setup. Microparticle velocimetry was combined with high-resolution oxygen profiling in the coral Porites lutea under varying current and light conditions with natural and arrested cilia beating. Cilia-generated vortices in the lower DBL mitigated extreme oxygen concentrations close to the tissue surface. Under light and arrested cilia, oxygen surplus at the tissue surface increased to 350 µM above ambient, in contrast to 25 µM under ciliary beating. Oxygen shortage in darkness decreased from 120 µM (cilia arrested) to 86 µM (cilia active) below ambient. Ciliary redistribution of oxygen had no effect on the photosynthetic efficiency of the photosymbionts and overall oxygen flux across the DBL indicating that oxygen production and consumption was not affected. We found that corals actively change their environment and suggest that ciliary flows serve predominantly as a homeostatic control mechanism which may play a crucial role in coral stress response and resilience.

Effect of Endometriosis to fallopian tube of the peristaltic-ciliary flow of third grade fluid in a finite narrow tube

The present prospective theoretical investigation deals with analysis of the peristaltic-ciliary transport of a developing embryo within the fallopian tubal fluid in the human fallopian tube under the effect6 of Endometriosis. This disease make the peristalsis ciliary flow become to peristalsis flow. A mathematical model induced flow of viscoelastic fluid characterized by the third grade fluid in a finite two dimensional narrow tube. That research is study the effect of couple stress to peristaltic –ciliary flow to Non-Newtonian fluids. Non-linear partial differential equations are solved by perturbation method. Flow variables like axial and radial velocities, appropriate residue time over tube length, pressure difference over have been derived under the assumption of long wavelength and low Reynolds number approximation and the expression for pressure rise is obtained by using wavelength and stream function are analysed for embedded parameter. This study is done through by the “MATHEMATICA”

Thermal analysis of electroosmotic flow in a vertical ciliated tube with viscous dissipation and heat source effects

Thermal analysis of electroosmotic flow of Newtonian fluid in the presence of viscous dissipation and heat source in a vertical ciliated tube is discussed. Three different cases of electroosmotic flow with heat source, viscous dissipation and buoyancy effects are presented, and their solutions are calculated analytically. Exact solutions for velocity and temperature field are calculated for the first case (presence of heat source and buoyancy force) and second case (presence of viscous dissipation), but the approximate solution is calculated by the Adomian decomposition method for the third case (presence of buoyancy force and viscous dissipation). The modeled equations of electroosmotic flow are reduced into simple equations by the long wavelength and low Reynolds number approximation. Influences of physical parameters are graphically computed for axial velocity, temperature profile, pressure gradient and stream function. It is observed that electroosmosis shows the significant effect on velocity and temperature profile in the presence of viscous dissipation and buoyancy force. This mathematical model gives a deep understanding to describe the thermal analysis in biomimetic ciliary flow and for the efficient flow of highly viscous fluid due to artificial cilia on glass tube used in laboratory.

Finely tuned ciliary alignment and coordinated beating generate continuous water flow across the external gills in Pleurodeles waltl larvae

Urodelan amphibian larvae develop three pairs of branching external gills on both sides of the pharyngeal region, and this study focuses on motile cilia on the gill surface. High-speed camera was used to observe ciliary strokes on the surface of the external gills of Pleurodeles waltl larvae. We found that the directionality of ciliary beating is position-dependent on the gill surface, and this rule is applicable to all the samples examined. For visualizing water flow around the external gills, we used bead suspensions. We revealed continuous anterior-to-posterior water flow generated by coordinated ciliary beating. Around the frontal surface of the gill stem (gill rachis), water flows countercurrent to the bloodstream beneath the gill epidermis. These results suggest that ciliary beating in each ciliated cell is coordinated, which cooperatively generates continuous and directional ciliary flow. We next visualized the overall distribution of ciliated cells on the gill surface by immunostaining of acetylated alpha-tubulin. Our results showed that the fine branches of external gills (fimbriae) have a circumferential distribution of cilia aligned orthogonal to the longitudinal axes of fimbriae, which facilitates water flow from proximal to the distal part of the fimbriae through the gills. This ciliary distribution pattern and directionality of cilia-driven flow are shared among five urodelan and two anuran species. Taken together, our findings suggest that the distribution and motility of ciliated cells on the surface of external gills is finely controlled, and this might support efficient respiration by the gills in urodeles.

5 Transport and cholinergic innervation in the bovine oviduct are dysregulated in cystic ovary disease

Cystic ovary disease (COD) is one of the most common causes of bovine infertility and affects 7-14% of cows in European herds. The morphological and molecular causes of this disease are largely unknown. Because the oviduct is pivotal to gamete transport, fertilization, and early embryonic development, the aim of this study was to analyse the effects of COD on the function of the oviduct. Oviducts were excised from cows affected by COD (n=29) as well as from healthy cows in mid diestrus (n=20) immediately after slaughter. A unique digital live cell imaging system established in our laboratory was used to capture real-time videos of ciliary beat and tubal fluid flow under near invivo conditions. For ciliary beat frequency, the differences in grayscale of beating cilia were transformed into frequencies using ImageJ (National Institutes for Health) and AutoSignal (SyStat Software Inc.). For particle transport speed (PTS), polystyrene beads were added to the buffer media and were automatically tracked using ImagePro (Media Cybernetics). Additionally, smooth muscle contraction and epithelial ion transport were investigated using organ baths and Ussing chambers. Our results showed that PTS was significantly decreased in oviducts from cows affected by COD as compared with controls (P=0.01, unpaired t-test). Further, in healthy control cows, PTS was consistently increased in the oviduct ipsilateral to ovulation as compared with the contralateral oviduct (P=0.03, paired t-test). This was not the case in cows affected by COD (P=0.47, paired t-test). Reduced PTS in oviducts from cows with COD was not due to changes in ciliary beat frequency. Although smooth muscle contraction was similar in oviducts from healthy and COD cows, the contractile response (mN) to the cholinomimetic drug carbachol (10−7-10−4 M) was significantly reduced in COD as compared with the controls (P<0.0001, nonlinear regression best fit analysis). Active epithelial ion transport, as measured by the change in short circuit current (μA cm−2), was stimulated by carbachol. Carbachol-induced active ion transport in the oviducal epithelium of COD cows was significantly decreased as compared with controls (P=0.03, unpaired t-test of area under the curve). These results suggest, for the first time, that the transport of the gametes and the early embryo might be impaired in COD. Further, inadequate or insufficient cholinergic innervation may result in dysregulated fluid flow, which might be associated with alterations in oviducal metabolism and gamete or embryo nutrition. This knowledge is pivotal to establish novel therapeutic concepts for successful treatment of infertility in individuals affected by COD.

Is the Zero Reynolds Number Approximation Valid for Ciliary Flows?

Stokes equations are commonly used to model the hydrodynamic flow around cilia on the micron scale. The validity of the zero Reynolds number approximation is investigated experimentally with a flow velocimetry approach based on optical tweezers, which allows the measurement of periodic flows with high spatial and temporal resolution. We find that beating cilia generate a flow, which fundamentally differs from the stokeslet field predicted by Stokes equations. In particular, the flow velocity spatially decays at a faster rate and is gradually phase delayed at increasing distances from the cilia. This indicates that the quasisteady approximation and use of Stokes equations for unsteady ciliary flow are not always justified and the finite timescale for vorticity diffusion cannot be neglected. Our results have significant implications in studies of synchronization and collective dynamics of microswimmers.

Simulation of the nodal flow of mutant embryos with a small number of cilia: comparison of mechanosensing and vesicle transport hypotheses.

Left–right (L-R) asymmetry in the body plan is determined by nodal flow in vertebrate embryos. Shinohara et al. (Shinohara K et al. 2012 Nat. Commun. 3, 622 (doi:10.1038/ncomms1624)) used Dpcd and Rfx3 mutant mouse embryos and showed that only a few cilia were sufficient to achieve L-R asymmetry. However, the mechanism underlying the breaking of symmetry by such weak ciliary flow is unclear. Flow-mediated signals associated with the L-R asymmetric organogenesis have not been clarified, and two different hypotheses—vesicle transport and mechanosensing—are now debated in the research field of developmental biology. In this study, we developed a computational model of the node system reported by Shinohara et al. and examined the feasibilities of the two hypotheses with a small number of cilia. With the small number of rotating cilia, flow was induced locally and global strong flow was not observed in the node. Particles were then effectively transported only when they were close to the cilia, and particle transport was strongly dependent on the ciliary positions. Although the maximum wall shear rate was also influenced by ciliary position, the mean wall shear rate at the perinodal wall increased monotonically with the number of cilia. We also investigated the membrane tension of immotile cilia, which is relevant to the regulation of mechanotransduction. The results indicated that tension of about 0.1 μN m−1 was exerted at the base even when the fluid shear rate was applied at about 0.1 s−1. The area of high tension was also localized at the upstream side, and negative tension appeared at the downstream side. Such localization may be useful to sense the flow direction at the periphery, as time-averaged anticlockwise circulation was induced in the node by rotation of a few cilia. Our numerical results support the mechanosensing hypothesis, and we expect that our study will stimulate further experimental investigations of mechanotransduction in the near future.

Mathematical analysis of flow of non-Newtonian fluid due to metachronal beating of cilia in a tube and its physiological applications

In the present paper, the ciliary flow of seminal fluid (non-Newtonian fluid) in the vas deferens (ductus efferentes) of the male reproductive tract is examined through a mathematical model. The rheological behavior of seminal fluid is described as a Hershel–Bulkley fluid. The momentum equations governing the flow of Herschel–Bulkley model are simplified by considering long wave-length and low Reynolds number approximations. The analytical solutions are obtained for velocity profile, flow rate, pressure gradient and flow impedance. The variation of plug core radius with respect to the cilia length (ε), the measure of the eccentricity of the elliptical motion (α), the wave number (β) and the time-mean flow rate (Qav) is reported for the first time. The time-mean flow rates obtained from the present study are compared with their experimental values of the transport of seminal fluid through the rhesus monkey reproductive track and the ductus efferentes of the male reproductive tract, respectively. It is observed that the theoretical values of time-mean flow rates for seminal fluid (Herschel–Bulkley fluid) have been found to be in good agreement with the experimental results.

Mechanical Strain Determines Cilia Length, Motility, and Planar Position in the Left-Right Organizer

The Xenopus left-right organizer (LRO) breaks symmetry along the left-right axis of the early embryo by producing and sensing directed ciliary flow as a patterning cue. To carry out this process, the LRO contains different ciliated cell types that vary in cilia length, whether they are motile or sensory, and how they position their cilia along the anterior-posterior (A-P) planar axis. Here, we show that these different cilia features are specified in the prospective LRO during gastrulation, based on anisotropic mechanical strain that is oriented along the A-P axis, and graded in levels along the medial-lateral axis. Strain instructs ciliated cell differentiation by acting on a mesodermal prepattern present at blastula stages, involving foxj1. We propose that differential strain is a graded, developmental cue, linking the establishment of an A-P planar axis to cilia length, motility, and planar location during formation of the Xenopus LRO.

Visualization and quantification of injury to the ciliated epithelium using quantitative flow imaging and speckle variance optical coherence tomography

Mucociliary flow is an important defense mechanism in the lung to remove inhaled pathogens and pollutants. Disruption of ciliary flow can lead to respiratory infections. Multiple factors, from drugs to disease can cause an alteration in ciliary flow. However, less attention has been given to injury of the ciliated epithelium. In this study, we show how optical coherence tomography (OCT) can be used to investigate injury to the ciliated epithelium in a multi-contrast setting. We used particle tracking velocimetry (PTV-OCT) to investigate the cilia-driven flow field and 3D speckle variance imaging to investigate size and extent of injury caused to the skin of Xenopus embryos. Two types of injuries are investigated, focal injury caused by mechanical damage and diffuse injury by a calcium chloride shock. We additionally investigate injury and regeneration of cilia to calcium chloride on ex vivo mouse trachea. This work describes how OCT can be used as a tool to investigate injury and regeneration in ciliated epithelium.

Vorticella: A Protozoan for Bio-Inspired Engineering

In this review, we introduce Vorticella as a model biological micromachine for microscale engineering systems. Vorticella has two motile organelles: the oral cilia of the zooid and the contractile spasmoneme in the stalk. The oral cilia beat periodically, generating a water flow that translates food particles toward the animal at speeds in the order of 0.1–1 mm/s. The ciliary flow of Vorticella has been characterized by experimental measurement and theoretical modeling, and tested for flow control and mixing in microfluidic systems. The spasmoneme contracts in a few milliseconds, coiling the stalk and moving the zooid at 15–90 mm/s. Because the spasmoneme generates tension in the order of 10–100 nN, powered by calcium ion binding, it serves as a model system for biomimetic actuators in microscale engineering systems. The spasmonemal contraction of Vorticella has been characterized by experimental measurement of its dynamics and energetics, and both live and extracted Vorticellae have been tested for moving microscale objects. We describe past work to elucidate the contraction mechanism of the spasmoneme, recognizing that past and continuing efforts will increase the possibilities of using the spasmoneme as a microscale actuator as well as leading towards bioinspired actuators mimicking the spasmoneme.

Effect of Fluid Viscosity on the Cilia-Generated Flow on a Mouse Tracheal Lumen.

Mucous flow in a tracheal lumen is generated by the beat motion of ciliated cells to provide a clearance function by discharging harmful dust particles and viruses. Due to its physiological importance, the cilia-generated flow and the rheological properties of mucus have been investigated intensively. The effects of viscosity on the cilia-generated flow, however, have not been fully clarified. In this study, we measured bulk background velocity of ciliary flow using a micro particle tracking velocimetry method under various viscosity conditions in mice. The results showed that the flow velocity decreased as the increase with viscosity of ambient fluid. Moreover, no previous study has clarified the pump power generated by cilia, which provides important information with regard to understanding the molecular motor properties of cilia. Measurements of both the ciliary flow and the ciliary motion were conducted to determine the cilia pump power. Our results indicated that the cilia pump during the effective stroke did not drive the ciliary flow efficiently under high viscosity conditions; these findings are necessary to resolve the clearance function.

Ciliary motion phenomenon of viscous nanofluid in a curved channel with wall properties

The present investigation is carried out to examine the ciliary flow of viscous nanofluid in a curved channel with wall properties. The governing equations are simplified under the well-known assumptions of long wavelength and low Reynolds number. Closed-form solutions for the nanoparticle temperature, velocity and streamlines are calculated and discussed. Numerical results for the velocity profile are also available in a table, for increasing values of the cilia length parameter.

Mechanical Strain Determines the Axis of Planar Polarity in Ciliated Epithelia

Epithelia containing multiciliated cells align beating cilia along a common planar axis specified by the conserved planar cell polarity (PCP) pathway. Specification of the planar axis is also thought to require along-range cue to align the axis globally, but the nature of this cue in ciliated and other epithelia remains poorly understood. We examined this issue using theXenopus larval skin, where ciliary flow aligns to the anterior-posterior (A-P) axis. We first show that a planar axis initially arises in the developing skin during gastrulation, based on the appearance of polarized apical microtubules and cell junctions with increased levels of stable PCP components. This axis also arises in severely ventralized embryos,despite their deficient embryonic patterning. Because ventralized embryos still gastrulate, producing a mechanical force that strains the developing skin along the A-P axis, we asked whether this strain alone drives global planar patterning. Isolated skin explanted before gastrulation lacks strain and fails to acquire a global planar axis but responds to exogenous strain by undergoing cell elongation, forming polarized apical microtubules, and aligning stable components of the PCP pathway orthogonal to the axis of strain. The planar axis in embryos can be redirected by applying exogenous strain during a critical period around gastrulation. Finally, we provide evidence that apical microtubules and the PCP pathway interact to align the planar axis. These results indicate that oriented tissue strain generated by the gastrulating mesoderm plays a major role in determining the global axis of planar polarity of the developing skin.

2B41 気道上皮の繊毛運動と流れに及ぼす粘液粘度の影響(OS1-3:自然界のバイオメカニクス・バイオミメティクス(3))

2B41 気道上皮の繊毛運動と流れに及ぼす粘液粘度の影響(OS1-3:自然界のバイオメカニクス・バイオミメティクス(3))