Studies of visible oscillating chemiluminescence in luminol–H2O2–KSCN–CuSO4 system using (2‐hydroxyethyl) trimethylammonium hydroxide

Visible oscillating chemiluminescence (CL) of luminol–H₂O₂–KSCN–CuSO₄ was studied using the organic base (2‐hydroxyethyl)trimethylammonium hydroxide. The effect of concentrations of luminol, H₂O₂, KSCN, CuSO₄ and the base were investigated in a batch reactor. This report shows how the concentration of components involved in the oscillating CL system influenced the oscillation period, light amplitude and total time of light emission. The oscillating CL with different bases was also investigated. Results indicated that using 2‐HETMAOH causes regular oscillating CL with nearly the same oscillating period. Copyright © 2008 John Wiley & Sons, Ltd.     

Oscillating viscometer--evaluation of a new bedside test

A viscometer for bedside blood measurements was developed, consisting of an oscillating resonator probe mounted directly into a disposable vacutainer tube for blood withdrawal. It was tested in vitro on blood samples with variable hematocrits (20-60%), increasing fibrinogen concentrations (0-20 g/l), increasing concentrations of an admixed radiographic contrast medium and erythrocyte suspensions in dextran 40 and dextran 70. Results were compared with those obtained with a conventional Couette viscometer. Oscillating viscometry yielded generally higher values than Couette viscometry, and had a good sensitivity for changes in hematocrit with a good correlation between the two methods (r=0.96, p<0.0001). Oscillating viscosity depended on the resonator frequency, it was higher at 3900 Hz than at 215 Hz, suggesting a viscoelastic behavior of blood. Erythrocyte aggregation, induced by increasing fibrinogen concentrations or dextran 70, affected oscillating viscometry. At a high frequency, i.e. a smaller penetration depth of the shear wave, oscillating viscosity tended to decrease, which suggests a depletion of the boundary layer from erythrocytes when they aggregate. At low frequency with a deeper shear wave penetration (about 50 microm), erythrocyte aggregation increased oscillating viscosity. Bedside tests in 17 patients with coronary heart disease and 10 controls confirmed the easy practicability of the test and showed lower oscillating viscosity in these patients despite higher fibrinogen concentrations presumably due to increased erythrocyte aggregation. We conclude that oscillating viscometry is an interesting bedside test, which is capable of providing new information on the biorheology of the erythrocyte-poor boundary layer near the vessel wall.     

细胞离子在振荡电磁场作用下的受力模型分析

本文通过生物细胞模型,研究振荡电场、振荡磁场以及振荡磁场产生的感应电场对细胞离子的作用机理。模型分析结果表明,电场力和罗仑兹力对细胞膜两侧的自由离子将产生加速度,振荡离子将产生周期性电位移。该模型同时也解释了脉冲电磁场比同参教的连续场产生更多的生物效应,以及连续场在开始施加和切除时的效应最大。     

A mechanism for action of oscillating electric fields on cells

The biological effects of electromagnetic fields have seriously concerned the scientific community and the public as well in the past decades as more and more evidence has accumulated about the hazardous consequences of so-called "electromagnetic pollution." This theoretical model is based on the simple hypothesis that an oscillating external electric field will exert an oscillating force to each of the free ions that exist on both sides of all plasma membranes and that can move across the membranes through transmembrane proteins. This external oscillating force will cause a forced vibration of each free ion. When the amplitude of the ions' forced vibration transcends some critical value, the oscillating ions can give a false signal for opening or closing channels that are voltage gated (or even mechanically gated), in this way disordering the electrochemical balance of the plasma membrane and consequently the whole cell function.     

Studies of visible oscillating chemiluminescence with a luminol–H2O2–KSCN–CuSO4–NaOH system in batch reactor

Oscillating chemical reactions are complex systems involving a large number of chemical species. In oscillating chemical reactions some species, usually reaction intermediates, exhibit fluctuation in concentration. Visible oscillating chemiluminescence, produced by the addition of luminol (3‐aminophthalhydrazide) to the oscillating system H₂O₂–KSCN–CuSO₄–NaOH, was investigated. In this study the effect of varying the concentration of H₂O₂, KSCN, CuSO₄, NaOH and luminol was investigated in a batch reactor. We showed that the concentration of all components involved in the oscillating chemilumenscent reaction influenced the light intensity and the oscillation period. Copyright © 2002 John Wiley & Sons, Ltd.     

Oscillating contractions in protoplasmic strands of Physarum: effects of externally applied ouabain, sodium-, potassium- and calcium-ions.

1. Concentrations of 0.1-10 mM Ouabain do not affect oscillating contractions, when applied externally in physiological solutions. 2. Ouabain has no effect, when applied in solutions of increased sodium- (100 mM) and lowered potassium-concentration (0.1 or zero mM). 3. De novo generation of oscillating contractions in protoplasmic drops is not suppressed in Ouabain-solutions. 4. Biochemical studies of Na-K-ATPase did not show any Ouabain sensitive ATPase-activity. 5. Reaction of veins on high concentrations (300 mosm) is discussed as to be a physical effect. 6. It is concluded that no Na-K-ATPase is engaged in triggering oscillating contraction automaticity.     

Spreading Speeds in Slowly Oscillating Environments

In this paper, we derive exact asymptotic estimates of the spreading speeds of solutions of some reaction-diffusion models in periodic environments with very large periods. Contrarily to the other limiting case of rapidly oscillating environments, there was previously no explicit formula in the case of slowly oscillating environments. The knowledge of these two extremes permits to quantify the effect of environmental fragmentation on the spreading speeds. On the one hand, our analytical estimates and numerical simulations reveal speeds which are higher than expected for Shigesada–Kawasaki–Teramoto models with Fisher-KPP reaction terms in slowly oscillating environments. On the other hand, spreading speeds in very slowly oscillating environments are proved to be 0 in the case of models with strong Allee effects; such an unfavorable effect of aggregation is merely seen in reaction-diffusion models.     

Angular acceleration,compensatory head movements and the halteres of flies (Lucilia serricata)

Summary Tethered flies were subjected to accelerations about their vertical axes while flying or walking. These accelerations were applied either suddenly to stationary animals or continuously by oscillating the animal from side to side. Head and wing movements resulting from the imposed angular accelerations were photographed with a camera and a stroboscopic flash.Analysis of the photographs shows that the wing movements act to counter the imposed angular accelerations and that during sinusoidal oscillations about the vertical axis, head turns are in antiphase with angular acceleration.Head turns do not occur when the halteres are absent or present and not oscillating. When oscillating, the halteres detect high values of angular acceleration, outside the known capabilities of the visual movement detection system.     

Effects of diurnally oscillating pCO2 on the calcification and survival of coral recruits

Manipulative studies have demonstrated that ocean acidification (OA) is a threat to coral reefs, yet no experiments have employed diurnal variations in pCO(2) that are ecologically relevant to many shallow reefs. Two experiments were conducted to test the response of coral recruits (less than 6 days old) to diurnally oscillating pCO(2); one exposing recruits for 3 days to ambient (440 μatm), high (663 μatm) and diurnally oscillating pCO(2) on a natural phase (420-596 μatm), and another exposing recruits for 6 days to ambient (456 μatm), high (837 μatm) and diurnally oscillating pCO(2) on either a natural or a reverse phase (448-845 μatm). In experiment I, recruits exposed to natural-phased diurnally oscillating pCO(2) grew 6-19% larger than those in ambient or high pCO(2). In experiment II, recruits in both high and natural-phased diurnally oscillating pCO(2) grew 16 per cent larger than those at ambient pCO(2), and this was accompanied by 13-18% higher survivorship; the stimulatory effect on growth of oscillatory pCO(2) was diminished by administering high pCO(2) during the day (i.e. reverse-phased). These results demonstrate that coral recruits can benefit from ecologically relevant fluctuations in pCO(2) and we hypothesize that the mechanism underlying this response is highly pCO(2)-mediated, night-time storage of dissolved inorganic carbon that fuels daytime calcification.     

Metastable balancing oscillators

The problem of an oscillator performing oscillations at the top of an oscillating potential barrier is solved exactly. The conditions under which the motion is finite, quasi-finite (metastable), or infinite are determined. Examples are presented from mechanics (a Kapitsa pendulum on a solid support that oscillates in the horizontal direction), plasma physics (Bernstein-Green-Kruskal waves), and microwave electronics (metastable electrons near an oscillating virtual cathode).     

Oscillating fluid flow regulates cytosolic calcium concentration in bovine articular chondrocytes.

Mechanical loading is a well-known regulator of cartilage metabolism. This suggests that a loading-induced physical signal regulates chondrocyte behavior. Previous studies have focused on the effects of steady fluid flow on chondrocytes. In contrast to steady flow, loading induced fluid flow occurs in an oscillatory pattern and includes a reversal of flow direction with each loading event. In this study we examined the hypothesis that oscillating fluid flow increases cytosolic Ca2+ concentration ([Ca2+]i) in bovine articular chondrocytes (BAC) in a frequency-dependent manner and that the presence of serum affects this response. The aims of our study were to examine (1) whether BAC respond to physiologic oscillating fluid flow in vitro and compare these results to steady fluid flow, (2) the effect of fetal bovine serum on fluid flow responsiveness of BAC and (3) whether the response of BAC to fluid flow is flow rate and/or frequency dependent. [Ca2+]i was quantified using the fluorescent dye fura-2. BAC were exposed to steady, 0.5, 1, or 5 Hz sinusoidal oscillating fluid flow at five different flow rates in a parallel plate flow chamber. Our findings demonstrate that BAC respond to oscillating fluid flow with an increase in [Ca2+]i (p > 0.05), and furthermore, chondrocyte responsiveness to fluid flow increases with peak flow rate (p < 0.0001) and decreases with increasing frequencies (p < 0.0001). Finally, the presence of serum in the media potentiated the responsiveness of BAC to fluid flow (p < 0.0001). Our results suggest an important role for mechanical load-induced oscillating fluid flow in chondrocyte mechanotransduction.     

Oscillating chemiluminescence with thiosemicarbazide in a batch reactor

Oscillating chemical reactions are complex systems involving a large number of chemical species. In oscillating chemical reactions, some species, usually reaction intermediates, exhibit fluctuations in their concentration. In this report, a novel slowly‐damped oscillating chemiluminescence produced by the addition of thiosemicarbazide (TSC) to the oscillating system H₂O₂–KSCN–CuSO₄–NaOH was investigated. Narrow and slightly asymmetric light pulses of 1.5 s half‐width are emitted at 440 nm, with an oscillation period of 22–363 s, an induction period of 9–397 s and an emitted light time of 700–1500 s, depending on reagent concentrations. In this study the dependence of the induction period and the oscillation period on the reagent concentrations was investigated and both parameters were plotted with respect to reagent concentrations. Copper concentration showed a significant effect on the oscillation period. A possible mechanism for the oscillating chemiluminescence reaction is discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

The “mechanostat” principle in cell differentiation. The osteochondroprogenitor paradigm

The “mechanostat” principle may be depicted as an oscillating signal of a signaling molecule, in which the amplitude, frequency, cumulative level, delay, and duration of the curve encode the information for concrete cellular responses and biological activities. When the oscillating signal is kept sustained (present delay), cell exit may be performed, whereas when the oscillating signal remains robust, cell proliferation may take place. B-catenin–Wnt signaling pathway has a key role in the differentiation of osteochondroprogenitor cells. Sustained downregulation of the β-catenin–Wnt pathway forces osteochondroprogenitors to a chondrogenic fate instead of an osteoblastic one. Other signaling, for example, bone morphogenetic protein and Notch signaling pathways interact with the Wnt pathway. The crosstalk between biochemical and mechanical stimuli produces the final information that leads to the final cell fate decisions, through the “mechanostat” principle.     

Impedance characterization of a piezoelectric immunosensor. Part I: antibody coating and buffer solution

This study investigated the impedance characteristics of a 5 MHz quartz crystal resonator oscillating in a thickness-shear mode for utilization as a biosensor. An impedance analyzer measured the impedance of the quartz crystal, which determined all mechanical properties of the oscillating quartz and its immediate environment. In this study, the impedance behavior of the oscillating crystal was characterized in air, in potassium phosphate buffer solution, and with immobilization of antibodies using protein-A. The potassium phosphate buffer behaved like a Newtonian liquid. The series resonance frequency shifted down about 900 Hz on contact with the buffer. An immobilized-antibody layer on the quartz surface behaved like a rigid mass when immersed in the buffer solution. The impedance curve following immobilization of antibodies was shifted down in frequency by about 200 Hz compared with its value when the bare crystal was immersed in the buffer solution.     

Perturbation of the tris(2,2′‐bipyridine) ruthenium(II)‐catalyzed Belousov–Zhabotinsky oscillating chemiluminescence reaction by l‐cysteine and its application

Perturbation of the tris(2,2′‐bipyridine)ruthenium(II) [Ru(bpy)₃²⁺]‐catalyzed Belousov–Zhabotinsky (BZ) oscillating chemiluminescence (CL) reaction induced by l ‐cysteine was observed in the closed system. It was found that the CL intensity was decreased in the presence of l ‐cysteine. Meanwhile, oscillation period and oscillating induction period were prolonged. The sufficient reproducible induction period was used as parameter for the analytical application of oscillating CL reaction. Under the optimum conditions, the changes in the oscillating CL induction period were linearly proportional to the concentration of l ‐cysteine in the range from 8.0 × 10^?7 to 5.0 × 10^?5 mol L^?1 (r = 0.997) with a detection limit of 4.3 × 10^?7 mol L^?1. The possible mechanism of l ‐cysteine perturbation on the oscillating CL reaction was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Computer simulation of synchronization of Na/K pump molecules

The behavior of Na/K pump currents when exposed to an oscillating electric field is studied by computer simulation. The pump current from a single pump molecule was sketched based on previous experimental results. The oscillating electric field is designed as a symmetric, dichotomous waveform varying the membrane potential from −30 to −150 mV around the membrane resting potential of −90 mV. Based on experimental results from skeletal muscle fibers, the energy needed to overcome the electrochemical potentials for the Na and K-transports are calculated in response to the field’s two half-cycles. We found that a specially designed oscillating electric field can eventually synchronize the pump molecules so that all the individual pumps run at the same pumping rate and phase as the field oscillation. They extrude Na ions during the positive half-cycle and pump in K ions during the negative half-cycle. The field can force the two ion-transports into the corresponding half-cycles, respectively, but cannot determine their detailed positions. In other words, the oscillating electric field can synchronize pumps in terms of their pumping loops but not at a specific step in the loop. These results are consistent with our experimental results in measurement of the pump currents.     

Physiological performance of juvenile southern flounder, Paralichthys lethostigma (Jordan and Gilbert, 1884), in chronic and episodic hypoxia

Dissolved oxygen (DO) is proving to be one of the most important abiotic factors determining growth and survival of juvenile estuarine fish. In shallow, throughout estuarine systems, low DO can occur in two broad categories: a diel oscillating pattern resulting in repeated nocturnal hypoxia due to the photosynthesis-respiration cycle of algal populations, or as prolonged bottom water hypoxia or anoxia caused by stratification. A series of laboratory experiments was conducted to characterize the physiological performance of juvenile southern flounder, Paralichthys lethostigma, (55-65 mm TL) exposed to four treatments of DO: (1) constant normoxia (6.50+/-0.50 mg O(2) l(-1)), (2) constant hypoxia (2.79+/-0.19 mg O(2) l(-1)), (3) constant intermediate hypoxia (4.74+/-0.18 mg O(2) l(-1)), and (4) an oscillating oxygen environment cycling dielly between the normoxic and hypoxic levels (2.8-6.2 mg O(2) l(-1), daily mean=4.40 mg O(2) l(-1)). Routine respiration was positively correlated with DO level and increased significantly during the day in the oscillating treatment in response to increasing DO. Ventilation rates were negatively correlated with the DO level in the constant treatments and increased significantly at night in the oscillating treatment in response to nocturnal hypoxia. Similarly, hematocrit levels were negatively related to DO levels in the constant treatments after 5 and 26 days of exposure to the treatments. Hematocrit levels also increased significantly the oscillating treatment, apparently in response to the episodic nocturnal hypoxia. Growth was significantly reduced in the 2.8 mg O(2) l(-1) treatment and the oscillating treatment but not in the 4.7 mg O(2) l(-1) treatment. Acclimation was evident by an increase in growth rates from week 2 to week 3 and a decrease in hematocrit levels between 5 and 26 days of exposure in the 2.7 and 4.5 mg O(2) l(-1) treatments but was not evident in the normoxic or oscillating treatments. These results suggest that a juvenile fish must remain in even moderately low DO in order for acclimation to occur. The research presented demonstrates that correctly assessing habitat quality in terms of DO requires knowledge of a fish's physiological and environmental history.     

Effect of oscillating fluid flow stimulation on osteocyte mRNA expression

Structural adaptation of the bone tissue is mediated by loading-induced interstitial fluid flow within the bone microstructure. Within this framework, osteocytes fulfill the central mechanotransductive role in the bone remodeling process. While osteocytes have been demonstrated to be exquisitely sensitive to various forms of fluid flow stimulus in vitro, the effect of different oscillating fluid flow (OFF) parameters on osteocyte activity has yet to be systematically characterized. In this study, we investigate the effect of three OFF parameters on osteocyte activity in vitro and hypothesize that COX-2, RANKL, and OPG mRNA expression in osteocytes are sensitive to the OFF parameters: peak shear stress amplitude (0.5 Pa, 1 Pa, 2 Pa, and 5 Pa), oscillating frequency (0.5 Hz, 1 Hz, and 2 Hz), and total flow duration (1 h, 2 h, and 4 h). Our findings demonstrate that COX-2 mRNA levels are elevated in osteocytes subjected to higher peak shear stress amplitudes and longer flow durations, while RANKL/OPG mRNA levels decreased to a minimum threshold in response to higher peak shear stress amplitudes, faster oscillating frequencies, and longer flow durations. These findings suggest that dynamic fluid flow with higher peak shear stress amplitudes, faster oscillating frequencies, and longer loading durations provide the best conditions for promoting bone formation.     

Mathematical description of the stimuli to the lateral line system of fish,derived from a three-dimensional flow field analysis. III. The case of an oscillating sphere near the fish

The three-dimensional potential flow field of an oscillating sphere near a fish with an axially symmetric body was investigated mathematically. The spatial distributions of the stimuli to the lateral line system are derived from the flow-field analysis, taking into consideration the hydrodynamical interaction between the fish body and the flow of the oscillating sphere. This was done dependent on the location and the direction of oscillation of the sphere relative to the fish. The theoretical results are compared with measurements of the flow on the surface of a fish model.     

Evidence for Two Separate Purinergic Responses in Paramecium tetraurelia: XTP Inhibits Only the Oscillatory Responses to GTP

The purine nucleotide GTP causes a complex behavioral response and two distinct electrophysiological responses in the ciliated protozoan Paramecium tetraurelia. One of the two electrophysiological responses is an oscillating current that is responsible for the repeated backward swimming episodes that constitute the behavioral response to GTP. The second electrophysiological response is a sustained current whose relationship to the first is unknown. Here we show that the purine nucleotide XTP can completely block both the behavioral response to GTP and its associated oscillating current, but not the sustained current induced by GTP. Notably, XTP alone causes a sustained current similar to that induced by GTP. We believe the data support the notion that P. tetraurelia possesses two distinct signal transduction pathways sensitive to purine nucleotides: one specific for GTP that leads to oscillating currents and behavior, and a second pathway activated by GTP and other purine nucleotides that leads to a sustained current. Received: 22 August 1997/Revised: 20 January 1998