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Z Priel

Publications and source records attributed to Z Priel.

18 recordsLinked to original sources
PubMed1992

Possible mechanism of ciliary stimulation by extracellular ATP: involvement of calcium-dependent potassium channels and exogenous Ca2+.

Ciliary motility was examined optically in tissue cultures from frog palate epithelium and frog's esophagus as a function of extracellular concentration of adenosine 5'-triphosphate (ATP) and related compounds. The addition of micromolar concentration of ATP caused a strong enhancement of frequency and wave velocity in the direction of the effective stroke. Since adenosine 5'-[beta,gamma imido]-triphosphate (AMP-PNP), a nonhydrolyzable analog of ATP, produces the same effects, ATP hydrolysis is not required. The overall potency is ATP approximately equal to AMP-PNP greater than ADP much greater than adenosine greater than AMP. It is suggested that both the phosphate and the base moieties are involved in ATP binding. The enhancement of ciliary activity by extracellular ATP is dependent on the presence of extracellular Ca2+, which can be replaced by extracellular Mg2+. The effect of a number of potent inhibitors of the voltage-gated calcium channels on the stimulation of ciliary activity by ATP were examined. No effect was detected in the concentration range within which these agents are specific. On the other hand, quinidine, a potent inhibitor of K+ (calcium-dependent) channels, inhibits the effect of ATP. The following model is suggested: exogenous ATP interacts with a membrane receptor in the presence of Ca2+, a cascade of events occurs which mobilizes intracellular calcium, thereby increasing the cytosolic free Ca2+ concentration which consequently opens the calcium-activated K+ channels, which then leads to a change in membrane potential. The ciliary response to these changes is the enhancement of ciliary activity.

Adenosine Triphosphate↗
PubMed1991

Human in vitro nasal and tracheal ciliary beat frequencies: comparison of sampling sites, combined effect of medication, and demographic relationships.

In vitro nasal and tracheal ciliary beat frequencies (CBFs) were measured photometrically in brush samples of 15 patients undergoing bronchoscopy. Tracheal and nasal CBF values in these patients were found to be significantly correlated (r = .74, p less than .01), and the latter did not differ significantly from the nasal CBF of 80 subjects serving as controls. Premedication with morphine and atropine and local anesthesia with lidocaine hydrochloride significantly decreased the CBF. Among the control subjects, a significantly higher CBF (13.6 +/- 1.5 Hz) was found in the young age group (10 to 19 years) as compared to other groups (12.2 +/- 1.7 Hz). Gender and ethnic origin did not influence CBF in any age group. These data support the possible use of the in vitro study of nasal epithelium to reflect the CBF in the lower respiratory tract.

Adult↗
PubMed1990

On metachronism in ciliary systems: a model describing the dependence of the metachronal wave properties on the intrinsic ciliary parameters.

A mathematical model is proposed to explain the dependence of the direction and the length of the metachronal wave on parameters that characterize the ciliary beat, the dimensions of the cilia, and the geometry of their arrangement on the ciliated surface. The metachronal wave is decomposed into two mutually perpendicular components, which are chosen in such a way that the direction of one of them is in the direction of the effective stroke. The magnitudes of the two components are determined by using the concept of the time of delay between adjacent cilia. The properties of the metachronal wave are then calculated as a function of the ciliary parameters. The results obtained with the present model predict that the direction of the wave propagation is strongly dependent on the type of metachronism in the direction of the effective stoke and the polarization in time and in space of the ciliary beat. The metachronal wavelength is found to depend on four parameters: the ciliary length, the angle of the arc projected on the cell surface by the ciliary tip during the recovery stroke, the degree of asymmetry of ciliary beat, and the portion of the cycle occupied by the pause. The metachronal wavelength is also found to be only weakly dependent on the ciliary frequency. At this stage there exists relatively little experimental information with which to characterize fully the metachronal properties of ciliary systems. Even when only partial information exists, the model allows prediction, to within a certain range, of the direction of the wave propagation. It also suggests a possible mechanism for the influence of changes in environmental conditions on wave direction and wavelength. In several cases in which full information does exist, good agreement between the experimental findings and the predictions of the model is found. According to this model it will be worthwhile to invest more effort in measuring the time and space polarization of ciliary beating and times of delay between cilia.

Animals↗
PubMed1990

On self synchronization--aspects of flagellar and ciliary beating.

Mathematical models involving hydrodynamically coupled oscillators are proposed to explain some self-synchronization phenomena observed in flagella and cilia. It is shown using elementary mathematical analysis and computer simulations that the behaviors of the models proposed are similar to those observed in experiment.

Animals↗
PubMed1990

Ciliary activity under normal conditions and under viscous load.

Ciliary metachronism and motility were examined optically in muco-ciliary tissue cultures from three different systems: a) frog's palate epithelium, b) frog's oesophagus, and c) human nasal polyps. In addition, lateral cilia of Mytilus edulis (water transporting cilia) were examined. It was revealed that the degree of synchronization between muco-ciliary systems is lower than that of water transporting cilia. There are no significant differences between different muco-ciliary systems, within the accuracy of our measurement although relatively large statistical ensembles were used. In addition the wavelength and wave direction of the metachronal wave was examined. All four systems exhibit similar wavelength. The metachronal parameters of muco-ciliary systems exhibit fluctuations (as was demonstrated by the degree of synchronization), however, the magnitude and repetitivity of these fluctuations, is dependent on the loading of the ciliary system. We have loaded the system by increasing the viscosity of the medium. Under viscous load the frequency of the beating decreased. The metachronal wavelength became longer and the metachronal coordination type more orthoplectic.

Animals↗
PubMed1989

Interaction of calcium and vanadate with fluorescein isothiocyanate labeled Ca2+-ATPase from sarcoplasmic reticulum: kinetics and equilibria.

The interaction of Ca2+ and vanadate with fluorescein isothiocyanate (FITC) labeled sarcoplasmic reticulum (SR) Ca2+-ATPase has been studied by following the kinetics of changes in the reporter group fluorescence and equilibrium fluorescence levels. The vanadate species bound to the enzyme is clearly monomeric orthovanadate, probably H2VO4-. Vanadate binding is noncooperative, suggesting an absence of interactions between the Ca2+-ATPase subunits. The fluorescence experiments confirm the existence of a calcium-enzyme-vanadate complex (in the presence of magnesium). On the basis of the fluorescence properties of this complex, it is similar in its conformation to the calcium-enzyme complex, i.e., "E1-like" rather than "E2-like". However, Ca2+ binds to the enzyme-vanadate complex via sites that are only accessible from the interior of the SR vesicles. The complex Ca2E*Van, which is rapidly formed, isomerizes very slowly (t1/2 approximately 1 min) to the stable ternary complex. The mutual destabilization between bound vanadate and two bound Ca2+ ions is only 1.6 kcal/mol, much smaller than that produced by the interaction of calcium and phosphate.

Animals↗
PubMed1989

Synchronization between beating cilia.

A novel quantitative parameter is proposed to define and measure the degree of synchronization between two small ciliary areas. These areas can be close to or far from one another. The Pearson correlation factor is used to define the degree of synchronization by a single number. This approach is based on a computerized, dual photoelectric method which simulataneously measures the scattered light from two small areas on the ciliary epithelium or its tissue culture. The measurements were performed on tissue culture from frog's palate epithelium. It was found that: (a) the degree of synchronization decreases, as a function of distance; (b) the correlation is fairly high even at relatively large separations, when measured on the same patch; (c) on a given patch the synchronization factor is independent of the direction of the metachronal wave; (d) close disconnected ciliary cells exhibit fairly high correlation; (e) disconnected randomly choosen ciliary cells at relatively large separation distances exhibit relatively low correlation, smaller by a factor of 2 than the correlation factor at the same distances when measured along the metachronal wave; (f) the average frequencies' ratio and the metachronal wavelength can be used as first-order indicators of ciliary synchronization; (g) there is a spread of metachronal wavelengths even over a single well-organized patch.

Animals↗
PubMed1989

Effect of Chlamydia trachomatis infection on ciliary activity in single cells from cultures of human nasal polyps.

We have tested the hypothesis that the ciliary activity of epithelial cells from human nasal polyps is altered after infection with Chlamydia trachomatis. Ciliated epithelial cells from human nasal polyps were cultured and infected with C. trachomatis. The measurement of ciliary beating was based on a technique which enables one to monitor a fraction of a single ciliated cell. A marked decrease of ciliary beating frequency versus time was observed 24 h after infection with C. trachomatis. About 50% of the cilia of infected cells were paralysed 48 h post-infection. The potential effect of C. trachomatis infection on the physiological functions dependent on cilia is discussed.

Cell Movement↗
PubMed1989

Characterization of metachronal wave in beating cilia: distribution of phases in space.

We have examined phase differences between beating cilia measured in different directions on the surface. The measurements were performed on tissue cultures taken from frog palate epithelium. This experiment was based on a method developed earlier, which measures simultaneously scattered light from two different and relatively small areas. Moreover, the distance between the two small areas can be accurately defined and varied. Rotating the stage around the optical axis permits us to repat these measurements at different space angles. It was found that: a) the phase gradient is a periodic function of the angle of rotation; b) the periodicity can be described quantitatively by a cosine function; c) good agreement exists between Machemer's findings in protozoa and our results, despite the differences between the two systems and techniques used.

Animals↗
PubMed1988

Intensification of ciliary motility by extracellular ATP.

Ciliary metachronism and motility were examined optically in tissue cultures from frog palate epithelium as a function of extracellular ATP concentration in the range of 10(-7)-10(-3) M. The main findings were: a) upon addition of ATP the metachronal wavelength increased by a factor of up to 2. b) the velocity of the metachronal wave increased by a factor of up to 5. c) the frequency of ciliary beating increased by a factor of up to 2-3, the increase being temperature insensitive in the range of 15 degrees C-25 degrees C. d) the area under the 1-second FFT spectrum decreased by a factor of up to 2.5. e) the energy of the metachronal wave is increased by a factor of up to 9.5. f) all the spectrum parameters are subject to influence by ATP, as also by ADP and AMP. However, there are pronounced differences in the various responses to them. Based on these findings, physical aspects of the rate increase of particle transport caused by addition of extracellular ATP are explained. A plausible overall chemical mechanism causing pronounced changes in ciliary motility is discussed.

Adenosine Triphosphate↗
PubMed1987

Characterization of metachronal wave of beating cilia on frog's palate epithelium in tissue culture.

1. A method is suggested to measure phase versus distance between beating cilia by means of a photoelectric device. A statistical method interpreting the results thus obtained is discussed. 2. It was found that: (a) an average phase exists between beating cilia, (b) despite strong fluctuations in phase on a short time scale, the average phase was kept constant over periods of 8 h, (c) the ciliary frequency and the length of the metachronal wave can be measured simultaneously. 3. The average phase differences are linearly dependent on distance. 4. The effective range of synchronization between cilia is of the order of 10 micron indicating that it occurs within one cell. 5. During the cycle of ciliary beating there are periods where coupling is stronger.

Animals↗
PubMed1987

Direct measurement of the velocity of the metachronal wave in beating cilia.

Recently a computerized electro-optical method was developed which enables one to simultaneously measure the frequency and the wavelength of the metachronal waves in beating cilia. The method is based on measurement of scattered light from two areas at a given distance apart. The distance between measured areas can be varied from zero to hundreds of microns. The relative ease of the measurement and data analysis of this method enable one to create large statistical ensembles in order to obtain reliable averages. In this work we show that in addition to the previously mentioned parameters this system can measure directly the velocity of the metachronal wave. It was found that the average velocity in the tissue culture from frog's palate epithelium at room temperature is approximately 270 micron/sec, about twice the average particle velocity at the frog's palate.

Animals↗
PubMed1986

Spectral characterization of ciliary beating. Temperature dependence on spectral parameters.

Ciliary beating was optically examined in tissue cultures from frog palate epithelium. Consecutive segments of the analog signal were Fast-Fourier transformed. The three main parameters which define the spectrum, position of the peak maximum (f), width of the spectral line (S.D.), and area (A) under the spectrum, were all measured as a function of temperature. These measurements were also examined as a function of the number of cilia by varying the examined area from 1.2 to 122 microns2. It was found that: all the parameters were exponentially temperature dependent; and the average frequency was independent of the number of cilia examined, while S.D. was dependent on it. On a physiological level, we demonstrated that the ciliary fluctuation in frequency is temperature dependent, increasing with increase in temperature. Moreover, it was shown that where a relatively small number of cilia were measured (d = 1.24 micron), the area A under the observed spectrum was directly proportional to the amplitude of ciliary beating. Increasing the temperature decreases the amplitude and vice versa. According to our suggested model the dependence of A on f was predicted and verified experimentally. A mathematical model which simulates the S.D. as a function of examined area and temperature is suggested. The calculated results from the model are in a good agreement with our experimental findings.

Animals↗
PubMed1986

Simultaneous binding of calcium and vanadate to the Ca2+-ATPase of sarcoplasmic reticulum.

The interaction of vanadate with the Ca2+-ATPase of sarcoplasmic reticulum vesicles has been studied by making use of the ATPase activity as a measure of uncomplexed enzyme. The binding/dissociation is slow, so that initial rates can be used to study the equilibrium binding. The results indicate that in addition to a Ca2+-free complex E.Van (KV = 0.4 microM), there must also be a Ca2+-enzyme-vanadate complex (K'V = 7 microM). This observation is confirmed by the difference between the kinetics of decay of activity on vanadate addition, and on addition of ATP to enzyme preincubated with vanadate and Ca2+, which requires two enzyme-vanadate complexes. ATP increases the apparent affinity of the enzyme for vanadate by inducing calcium release. Upper limits for the kinetic parameters for vanadate binding and dissociation are estimated.

Adenosine Triphosphate↗
PubMed1986

Spectral characterization of ciliary beating. Biological meaning of the spectral linewidth.

The ciliary beating frequency in tissue culture from frog palate and lung was examined optically. Consecutive segments of the analog signal were then fast-Fourier transformed (FFT). The optical signals were measured as a function of the number of cilia by varying the examined area from 1.2 to 122 micron 2. The frequency of the maximum power of the spectra was independent of the measured area, while the line shape of the spectra and distribution of the main frequencies were strongly dependent on the dimensions of the area examined. The possibility that the width of the measured spectral peak reflects both the distribution of the beating frequencies and the distribution of the phases within the examined area is discussed.

Animals↗
PubMed1985

Ciliary motility in brain ventricular system and trachea of hamsters.

Ciliary beat frequency (CBF) in various parts of brain ventricular system, as well as in trachea of hamsters, was examined. Coronal sections of brain and tracheal rings were maintained in a thermostatically controlled perfusion chamber and CBF measured by a photoelectric system equipped with a fiber-optic probe. CBF (Hz) values of lateral ventricle, aqueduct and fourth ventricle were 27.9 +/- 4.6; 30.7 +/- 7.7 and 31.9 +/- 7.8 Hz, respectively. CBF in the third ventricle--19.8 +/- 7.1 Hz--was significantly lower than in other segments of ventricular system. CBF in choroid plexus cilia was very slow, 5-10 Hz, whereas in tracheal rings amounted to 13.7 +/- 3.1 Hz. Bovine cervical mucus and mucus stimulant reversibly inhibited CBF in brain but not in trachea. Brain cilia in contrast to those in trachea were not capable of transporting particles. In addition to demonstrating differences between tracheal and ependymal cilia, this work suggests that cilial motility plays a functional role in local mixing of cerebrospinal fluid, but does not relate to the bulk flow within the ventricular system.

Animals↗
PubMed1985

Spectral characterization of ciliary beating: variations of frequency with time.

Ciliary beating frequency in tissue culture from frog palate and isolated lung was optically examined using instrumentation that was adjusted to measure a fraction of the surface area of a single ciliary cell. Consecutive 1-s segments of the analogue signal were fast Fourier transformed (FFT) to obtain a power spectrum. At room temperature, these power spectra changed over time from 1 s to the next. Each spectrum contained several dominant frequencies of similar intensities. Cooling the preparation resulted in a single-peak spectrum that was constant over time. A mathematical model is proposed to simulate these findings. The results and the mathematical model support the hypothesis that ciliary beating frequency fluctuates over short periods of time.

Animals↗