[Changes in the rate of sinoatrial node after high-frequency stimulation of the heart atrium].

Variations in the sinus node rate of the frog heart isolated together with the atria were studied during suprathreshold atrial stimulation at a frequency exceeding the intrinsic sinus node rate. If the stimulation frequency surpassed the intrinsic sinus node rate by 20%, the sinus node rate became equal to the pacing rate. Provided the pacing rate was increased, the sinus node rhythm became irregular.

[Interactions of subunits of DNA gyrase].

Interaction of DNA gyrase A- and B-subunits during the process of DNA supercoiling was studied. For this purpose a E. coli Cour-1 mutant resistant to coumermycin and containing a mutation in the B-subunit of DNA gyrase was isolated and the influence of the DNA gyrase A-subunit specific inhibitor-nalidixic acid-on DNA supercoiling by wild-type and mutant enzymes was investigated.

Preparation and study of composite insecticido-repellent aerosols.

Insecticido-repellent mixtures sprayed on clothes, nets etc. are useful as a means of protection against attack by bloodsucking arthropods. These sprays provide repellence of insects sensitive to the repellent and kill those that are only weakly repellent sensitive.

Changed properties of the A subunit in DNA gyrase with a B subunit mutation.

To investigate the interaction of subunits A and B of DNA gyrase during DNA supercoiling, a Cour mutant of Escherichia coli was obtained and the effect of nalidixic acid on the supercoiling of DNA by wild-type and mutant enzymes was assayed. The enzyme of the Cour strain proved to be more sensitive to nalidixic acid than the wild-type DNA gyrase. Hence the mutation affecting the B subunit can also change the properties of the A subunit, which fact suggests that the two subunits of DNA gyrase are in contact during DNA supercoiling.

[Binding of 3H-serotonin, 3H-diazepam and lipid peroxidation in brain membranes].

It was demonstrated that the processes of lipid peroxidation in brain tissues of rats induced by hyperoxia and Fe-ascorbate system in vivo and in vitro significantly influence specific binding of serotonin and diazepam. Lipid peroxidation caused various changes in the ability to bind utilized ligands: 3H-serotonin binding decreased by 53%, while that of 3H-diazepam increased by 30%. Preliminary administration of the synthetic antioxidant 4-methyl-2,6-ditretbutylphenol prevented these changes.

[Sinoatrial block with Wenckebach's period: diagnosis by means of automatic analysis of the cardial rhythm structure and clinical evaluation].

Computer served to study by automatic analysis the structure of the cardiac rhythm in 190 patients: 123 patients after removal of the persistent form of atrial fibrillation, 24 with neuro-circulatory dystonia and 43 healthy individuals. Sino-atrial block with Samoilov-Wenkebach periods was recorded in 26 individuals. The characteristic changes of the cardiointervalogram in the given disorder of intracardiac conduction are described, which facilitates diagnosis considerably.

[Follow-up of patients with neurosis-like stuttering].

Clinico-catamnestic and logopedic examinations were carried out in 125 patients who had been suffering from grave neurosis-like spasmophemia since the speech mastering. By the time of the examination the patients' average age was 20 years. The examinations have shown that in 59%, of the patients the spasmophemia has ceased; 22% have had a considerable improvement; in 10% there was a slight improvement, and 9% showed no improvement at all.

[Atrial fibrillation process studied in clinical practice by using statistical analysis methods].

The results of studying the electrical activity of the atria in 53 patients with cardiac fibrillation by means of a special digital computer system are discussed. On the strength of the aggregate of amplitude, rate, and morphological characteristics, three varieties of fibrillation waves are distinguished. It is shown that in the absence of cardiotropic therapy, the principal regular features in the distribution of the ff waves according to the frequency ranges are preserved in one and the same patients for a long period of time.

[Effect of DNA supercoiling on transcription performed by normal and mutant Escherichia coli RNA-polymerases].

A specific DNA-gyrase, inhibitor, coumermycin A1, causes differential changes in the spectrum of proteins synthesized in E. coli wild types cells, while protein spectrum in the mutant cells with coumermycin-resistant DNA-gyrase is left unaffected. The mutation of RNA-polymerase RpoB265 lowers the sensitivity of bacteria to coumermycin A1, whereas the RpoC3 enhances it.