Dynamic surface tension of micellar solutions in the millisecond and submillisecond time range.

The analysis of the available bubble life times and dead times for the bubble pressure tensiometer BPA-1S shows that dynamic surface tensions can be measured also for surfactant solutions at concentrations many times higher than the corresponding CMC. For the three nonionic surfactants Triton X-100, Triton X-45, and C14EO8 experiments are performed for solutions with a concentration of up to 200 times the CMC (C14EO8). Comparison of the experimental data with micelle kinetics models yields rate constants for the fast micelle dissolution process, which are in a good agreement with values obtained by other experimental methodologies.

Reversibility and irreversibility of adsorption of surfactants and proteins at liquid interfaces.

It is shown experimentally that the desorption of sodium decyl sulphate from the liquid/air interface is purely diffusion controlled, while the desorption of higher surface active surfactants such as the non-ionic surfactants Triton X-100 and tridecyl dimethyl phosphine oxide obeys a mixed mechanism. The desorption kinetics of beta-lactoglobulin (BLG) and beta-casein is, however, determined by a barrier mechanism. From the analysis of the BLG and beta-casein desorption kinetics at different temperatures the activation energy of desorption is calculated.

Surface pressure isotherm for the fluid state of Langmuir monolayers.

The equation of state for the monolayer comprised of the molecules of different sizes (water and biopolymers) is modified to describe the fluid (liquid-expanded and gaseous) state of the insoluble molecules monolayer. In contrast to the equation of state derived previously in ref 1, this equation does not involve either the Gibbs' adsorption equation or the differential equation for the chemical potential of the insoluble component, but it is based only on the equations for the chemical potential of the solvent in the bulk and in the surface layer. The results calculated from the proposed equations are in perfect agreement with the experimental Pi-A isotherms of the liquid-expanded state obtained for Langmuir monolayers of various types of amphiphilic compounds.

Dysfunctional uterine bleeding in adolescents: concepts of pathophysiology and management.

DUB is extremely common in young adolescents, and can be regarded asa part of normal physiologic development. It is essential to have a firm grasp on normal physiologic development of the menstrual cycle to recognize the normal menstrual patterns of adolescents and to manage abnormal patterns that may develop. Specific management depends on the underlying cause, presence and extent of any existing anemia, and duration of the irregular menstrual pattern.

Surface-pressure isotherms of monolayers formed by microsize and nanosize particles.

The thermodynamic model of a 2D solution developed earlier for protein monolayers at liquid interfaces is generalized for monolayers composed of micro- and nanoparticles. Surface pressure isotherms of particle monolayers published in the literature for a wide range of particles sizes (between 75 microm and 7.5 nm) are described by the theoretical model with one modification.

[Analysis of heart rate variability in assessment of baroreflex sensitivity in anesthetized rats].

Spectral analysis of the heart rate variability can be used as a measure of baroreflex sensitivity in ketamine anesthetized rats. Stimulation of delta1-receptors with phenylephrine (0.01 mg/kg, i.

Interfacial tensiometry as a novel methodology for the determination of surfactant adsorption at a liquid surface.

At low surfactant concentration the loss of molecules in the bulk phase due to adsorption can be significant if the surface-area-to-bulk-volume ratio is large. This loss of molecules, however, can be used to determine the adsorption of a surfactant if the experiments are performed under well-controlled conditions. Experiments are performed with the model surfactant tridecyldimethylphosphine oxide (C13DMPO) using drop profile analysis and ring tensiometry.

Competitive adsorption from mixed nonionic surfactant/protein solutions.

A thermodynamic model is derived which is suitable to describe adsorption from a mixed protein/surfactant solution. The comparison with experimental data for HSA mixed with the nonionic surfactant decyl dimethyl phosphine oxide shows good agreement. Some model calculations are discussed in terms of the competitive character of the process of adsorption from mixed protein/surfactant solutions.

Maximum bubble pressure tensiometry--an analysis of experimental constraints.

The maximum bubble pressure tensiometry is the only technique that allows measurements of dynamic surface tensions of surfactant solutions in the short time range down to milliseconds and even below. To reach such extremely short adsorption times, many hydrodynamic and aerodynamic effects have to be taken into consideration in order to measure physical values or to correct for the respective influences. In particular, the design of the instruments, and essentially the geometry of the measuring cell and capillary, are of key importance for accurate experiments.

Description of the adsorption behaviour of proteins at water/fluid interfaces in the framework of a two-dimensional solution model.

In the framework of the two-dimensional non-ideal solution model, surface layer equations of state, adsorption isotherms and functions of the distribution of protein molecules in respect to different molar area were derived. The thermodynamic analysis was based on Butler's equation for the chemical potentials of the components and a first-order model for the non-ideality of surface layer enthalpy and entropy. For concentrated solutions, aggregation of protein molecules in the surface layer was assumed.

[Effect of modulator of the signal transmission from opioid receptor to sodium channels on hypothalamus self-stimulation].

We investigated effects of different doses of a new preparation comenic acid as a modulator of the transmission of signals from an opioid receptor to slow sodium channels on the hypothalamic rewarding system in male Wistar rats. Comenic acid has been shown to inhibit the reaction of the hypothalamic self-stimulation (SS) in a dose-dependent fashion with the strongest effect at doses of 28.8-30 mg/kg.

[Pneumo-automatic apparatus for the artificial ventilation of the lungs for small laboratory animals].

We have designed apparatus of artificial ventilation of the lungs (AAV) for small laboratory animals on pneumoelements, examined static and dynamic characteristics of a generator of impulse signals and chose rational parametres of the apparatus. Some advantages of that model as compared with its analogues have been proved. The apparatus was approved at electrophysiological experiments on rats, 200-250 g.

Comparison of various models describing the adsorption of surfactant molecules capable of interfacial reorientation.

The thermodynamic model for describing the adsorption of surfactant molecules in different adsorption states, the reorientation model, is reconsidered on a more rigorous level. The resulting model equations are used to describe experimental surface pressure data published in the literature. The new model proposed contains three physical parameters and describes the experimental dependencies Pi(c) for oxethylated alcohols very accurately.

Simple model for prediction of surface tension of mixed surfactant solutions.

A rigorous theoretical model is presented which describes the equilibrium behaviour of a surfactant mixtures at liquid/fluid interfaces. The theory describes mixtures of surfactants with different molar areas and accounts for the non-ideality of the surface layer. The theoretical results are in good agreement with experimental data and support the idea of additivity of the interaction parameters in the surface layer.

[Functional heterogenicity of human blood neutrophils: generation of oxygen active species].

Kinetics of neutrophil inactivation was investigated in vitro by Nitroblue tetrazolium (NBT) test in the process of their contact with the substrate. It has been shown that the previous thermostatation results in an exclusive inactivation of neutrophils with high reaction ability leading to their complete inactivation. Such an inactivation is a consequence of cell contacts with the substrate, whose chemical structure and physicochemical properties define the process regularities.

[Effects of ionol, alpha-tocopherol and lipin on the processes of peroxidation in the syndrome of prolonged crush].

Experimental investigations of the influence of ionol and alpha-tokoferol in combined usage and liposomes on the processes of lipids peroxidation in the heart and blood at the cellular and subcellular level during crunch syndrome were made. The injection of ionol and alfa-tokoferol combined and lipid decreases the production of lipids peroxidation and increase antioxidation organism status and as a result the survival abilities of animals. These data, refected antioxidation provision of the heart and blood under crunh syndrome at the cellular and subcellular levers are given.

Effect of surfactant interfacial orientation/aggregation on adsorption dynamics.

The application of new thermodynamic adsorption isotherms allow to improve the description of surfactant adsorption kinetics based on a diffusional transport. While the consideration of interfacial reorientation corrects apparently too high diffusion coefficients, interfacial aggregation avoids too small diffusion coefficients or the assumption of adsorption barriers. The adsorption kinetics of alkyl dimethyl phosphine oxides is influenced by interfacial reorientation.

Studies on the application of dynamic surface tensiometry of serum and cerebrospinal liquid for diagnostics and monitoring of treatment in patients who have rheumatic, neurological or oncological diseases.

Human biological liquids comprise various surfactants, which adsorb at liquid interfaces and lead to a variation in surface tension. The adsorption processes involving low molecular weight surfactants, proteins and phospholipids play a vital role in the physiological functions of the human organism, especially if large surfaces are involved (e.g.

[The neurochemical profile of the caudate nucleus in the anxiolytic action of benzodiazepine and nonbenzodiazepine tranquilizers on different models of anxiety].

In the experiments on rats in avoidance response to "eliminated area" and "threatening situation" it is found that the microinjection of monoamines and amino-acids of mediator action, adreno- and dophaminemimetics, their antagonists, and blocker of GABAA receptors picrotoxine into dorsal and ventral sections of caudate nucleus elucidates different functional value and neurochemical special features of examined neostriatum specimens in realization of anxiety states of different origin. Local injection of chlordiazepoxide, phenibutum, indoterum, campirone and campironine into aforementioned sections of the caudate nucleus reduces the state of anxiety in "eliminated area" and/or "threatening situation" response tests thus revealing the similarity with well-known effects of GABA and serotonin and substantial difference in the effects of catecholamines and glutamine acid. It is found that anti-anxious effect of benzodiazepine and nonbenzodiazepine anxiolytics can be mediated through participation of neuron matrices of dorsal and ventral sections of the caudate nucleus having functionally ambiguous neurochemical profile.

[Kinetics of the reaction of nitroblue tetrazolium reduction by human blood neutrophils].

Kinetics of Nitro blue tetrazolium (NBT) reduction to diformasan by neutrophils was investigated using 27 samples of human blood. Analysis of alteration in the share of activated neutrophils (ANP) and activated neutrophil index (ANI) was done in relation to the reaction time. The former reaction is an irreversible reaction of zero (pseudozero) order, while the latter is an irreversible reaction of the first (pseudofirst) order.

[The abdominal cavity microflora of children with appendicular peritonitis].

Specific features and variability of microflora have been investigated in 75 patients with appendicular peritonitis. The patients' age was from 2 to 15. Forty-five (45) children had local peritonitis, 17, diffuse and 13 children had total peritonitis.

[Convergence studies of hypothalamic neurons].

In this study has been reveibed the peculiarities of convergence of afferent cortical inputs to the hypothalamic neurons. Single and the serial stimulation of phylogenetically distinct cortical areas (proreal cortex (field 8), cingular cortex (field 24), pyriform lobule (periamygdala cortex), and hippocampus (CA3) were used. We have established two main focuses of expressed convergence of signals from the above mentioned cortical areas.

[The central mechanisms regulating the blood circulation in hyperuricemia].

In experiments conducted on male Wistar rats for elucidation the role of central mechanisms in development alterations of heart electric stability was studied activity of 5(1)-nucleotidase and adenosine desaminase in sensomotor cortex, hypothalamus and hippocamp. Were shown that changes of heart function were in case increased adenosine content in neurons of sensomotor cortex, hypothalamus and hippocamp. Introduction to animals with hyperuricemia DOCA, with activate 5(1)-nucleotidase and adenosine desaminase, was accompanied by changes of cAMP and cGMP content in neurons.