[The Effect of the Disease Duration on the Changes of the Visual Evoked Potentials and Contrast Sensitivity in Multiple Sclerosis].

The most sensitive methods to detect pathological changes in the visual system are the method of recording visual evoked potentials and the psychophysical method of measuring contrast sensitivity. Described in the literature features of functional disorders of the visual system in patients with multiple sclerosis are controversial. The results of the study allowed us to make an assumption about the depen-dence of the nature and severity of changes of the evoked potentials and contrast sensitivity and the duration of disease in patients with multiple sclerosis.

The human magno and parvo systems and selective impairments of their functions.

The magno and parvo systems, consisting of large and small cells respectively and showing the greatest differences in temporospatial characteristics, are two of the most interesting channels in the organization of retinotopic input pathways of the human visual system. We tested the hypothesis that selective lesions of fibers of a specified diameter occurring in pathology of the conducting pathways, i.e.

[Human magno- and parvo-systems and selective disruptions in their function].

In psychophysical and electrophysiological investigations, we tested the hypothesis that in patients with multiple sclerosis at its early stage either phasic cells of the magnocellular pathway or tonic cells of the parvocellular pathway are disturbed. Healthy humans and patients with early stage of diseases have a contrast spatial-frequency sensitivity measure. The decrease in sensitivity at low, medium and high spatial frequency indicates changes in parvo- and magno-system activity.

[Visual evoked potentials in response to dichoptic presentation of sinusoidal grating and noise background].

Dichoptic stimulation was used in comparison of visual evoked potentials (VEPs) with those obtained with monocular stimulation (recordings made from the occipital area). 16 subjects viewed sinusoidal gratings with the right eye while a visual noise was added via a mirror for the left eye. In presence of the noise, amplitude of the early VEP components' N1, P1b, and the late component P2 decreased, P1a is not changed in presence of the noise, and the late negative wave N2 increased for all spatial frequencies.

[Individualization of the amikacin administration regimen on the basis of the relationship between its pharmacokinetics and the patient's status].

Dosage individualization based on quantitative relationships between pharmacokinetic parameters and anatomophysiological and/or pathological factors, patient's factors (PFs) is of importance in designing optimal regimens. Unfortunately, the attempts to correlate aminoglycoside pharmacokinetic parameters and PFs often failed perhaps due to insufficient numbers of PFs under investigation. That is why we sought to involve more PFs, especially nontraditional ones, for explaining intersubject variability of the amikacin model-independent parameter in 20 patients with purulent inflammatory processes.

Results and perspectives of collaboration of CMEA member countries in the field of developing sanitary-chemical methods of determining toxic compounds in the air and biomedia.

Some theoretical and practical problems of controlling industrial environment and biological substrates in the CMEA countries are discussed. Particular attention has been paid to the unification of methodological instructions concerning common requirements and methods of supervision, as also to the coordination and unification of the methods of determining some chemical compounds in the air of the working zone and in biological materials.

[Elimination of admixtures from antibiotic sediments during their treatment with solvents].

A model for determination of the admixture concentration in the secondary mother solution was developed. The concentration was determined depending on the solvent volume used for repulping the precipitate and on the impurity level of the initial antibiotic paste. When the values of X1 and X2 are known it is possible to estimate the amount of the admixtures remaining in the paste layer after separation of the secondary mother solution with regard to the volume of the latter in the precipitate pores.

[Prognosing the viability of lyophilized Actinomyces parvullus spores based on the "accelerated storage" method].

A technique of "accelerated storage" was used to evaluate promptly the effectiveness of protective (suspension) media for lyophilization and further storage of spores of Actinomyces parvullus 99. The number of survived spores can be predicted using the Arrhenius diagram and the van't Hoff rule. Equine serum without a conserving agent was found to be the most effective protective medium for lyophilizing spores of Act.

[Development of an automated information retrieval system for the identification of antibiotics].

The basic points in the development of a specialized computer information search system providing ientification of new antibiotics at early stages of their investigation are described. The system of coding the physico-chemical properties of the agents and the spectra of their antimicrobial activity presenting the substance in the information bank is developed. The task of identification is to find in the reference bank according to some specially organized keys such antibiotics which are identical or close by their properties to the substance being identified.

[Mathematical analysis of the n-cholinolytic effects in experiments with the isolated frog rectus abdominis muscle].

An inquiry into the nature of antagonism of alpha-tubocurarine and gentamycin to acetylcholine based on a mathematical analysis of cumulative curves obtained in experiments with an isolated musculus rectus abdominalis of the frog showed that the character of changes in the parameters of cumulative curves occuring under the effect of alpha-tubocurarine cannot be explained from the standpoint of Clark's (1929) "employment theory", but accords with deductions drawn from a more general theory of allosteric interaction of substances and receptors (Karlin--1967) in competitive antagonism. Variations in the parameters of cumulation curves occurring under the action of gentamycin may be regarded as a manifestation of non-competative to acetylcholine in conformity with both theories.

[Use of a 2-part model of i pharmacokinetics of gentaniycin for maintaining a constant blood concentration in infusion intravenous (an experimental study)].

Maintenance of constant antibiotic blood levels within the required ranges may be accomplished with mathematical modelling of the antibiotic pharmacokinetics. The problem solvation was illustrated on gentamicin. The kinetic analysis of the curves of the drug excretion from the blood after a one-moment intravenous administration of the antibiotic to cats provided estimation of the constants for a two-compartment model of its pharmacokinetics.