Biomedical subjects
Publications and source records attributed to O Sova.
The autofocusing separation of nine antibiotics was investigated: tetracycline and chloramphenicol in large-scale batches, and seven others in gram preparation amounts. All except one were found to be heterogeneous in autofocusing, and 2-4 well-characterized fractions emerged. These heterogeneities are described and the industrial utilization of the procedure is suggested.
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The authors studied the effect of a protein-free diet on 14C-thymidine incorporation into rat liver DNA in vivo and found, after 2-3 weeks, a marked decrease in uptake of the radioactive base into the liver DNA, followed by a decrease in the proportion of DNA in liver cell homogenates. The total nuclear count/mg liver tissue displayed an increase during protein depletion, except for the 5th week, when a decrease was recorded. The incorporation of 14C thymidine into the brain DNA likewise displayed no great differences, although a significant drop was observed during the 2nd to 4th week of depletion. In the 5th week we recorded an increase in uptake of the radioactive base by brain DNA, exceeding the incorporation values in the controls.
The authors attempted to determine whether repeated protein depletion would produce changes in the organism's response to this unfavourable situation indicative of the preservation of information on past depletion and of its inclusion in the formation of the organism's defences against repetition of this unphysiological state. It can be concluded from the results that the anticipated trend was demonstrated. The question of the site of origin, storage and action of this information was not resolved.
The authors studied the response of the regulation of proteosynthesis in the rat organism at the level of a model protein--haemoglobin--during developing protein depletion, comparing the response of rats encountering this situation for the first time with the response of animals specially prepared for it by a multiple depletion-repletion cycle. The changes in the response of both groups of animals to the same stimulus indicate that the data acquired in experience of these states are stored in the organism and form the basis of its changed response to a fresh load. The authors did not study the mechanism and site of storage of the information in question, or the mechanism of coordinated regulation, but they expressed the hypothesis that central regulation of protein biosynthesis could be involved.
The authors submit the results of a study of the effect of rhytmic alternation of protein depletion and repletion on the quantitative and qualitative proportion of haemoglobin in the rat. The results show that four weeks' depletion caused significant changes in the studied parameters, but that two weeks' repletion restored them to normal. The organism's responses to repeated depletion-repletion states were heterogeneous as regards the size, quality and trend of the changes, indicating that the organism's defences against depletion can be influenced by repeated administration in the form of a kind of "training". The mechanism of action of the above changes is at present still unknown.
Comparison of the dynamics of changes in the proportion of the serum protein during progressive protein depletion in rats specially adapted to this situation and animals exposed to it for the first time, led the authors to conclude that the regulation of proteosynthesis is largely adaptable, that it can be influenced by nutritional leads and that the organism probably stores information on past nutritional loads and makes use of it to help to overcome fresh insults.
Study of the quantitative distribution of cystinaminopeptidase activity in the serum of pregnant and control animals (cow, sheep and rat) by the isoelectric focusing method showed heterogeneity of the cystinaminopeptidase activity of the animals' serum enzymatic system, which was well pronounced in the cow and rat and less pronounced in the sheep. The authors assume from their results that the principal difference between the pregnant and control animals is not the total increase in the level of activity of the enzyme in question, but the shift in its incidence, or the increase in activity at a given pH. It is possible that pregnancy, in man and animals, produces in the serum cystinaminopeptidase system (which is evidently heterogeneous even under normal, physiological conditions) given changes, i.e. the formation of new fractions with a different pI from the controls; other fractions disappear, or their activity diminishes.
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The functional state of the rat liver, brain and muscle proteosynthetic apparatus during developing protein depletion was studied, with special reference to the effect of brain cytosols on the synthetic capacity of liver and muscle ribosomes. The results indicate that both stimulant and inhibitory agents (so far unidentified) may be present in brain cytosols during protein depletion.
The authors studied the effect of protein depletion on the RNA content of rat liver and brain and on the incorporation of 14C-leucine into the microsomal and soluble liver and brain fractions. They failed to find a direct relationship between the amount of RNA and the rate of proteosynthesis in the organs in question. The changes found in 14-C-leucine incorporation are discussed in relation to previous studies.
The authors studied the dynamics of natural substrates of neurohumoral origin (oxytocin and lysine-vasopressin) by the serum of pregnant and nonpregnant women in relation to the pH in the medium, within pH limits of 2.5 to 8. The values obtained in a polarographic study of depression of the complex oxytocin and lysine-vasopressin polarographic wave by pregnancy and non-pregnancy sera and the results of a parallel analysis of free amino acids of the inactivated substrates under the same conditions showed that, apart from deep degradation of the studied substrates at the optimum pH (5.5 minus 8), less pronounced degradation of the molecule at low pH values (3 minus 4,5), i.e. in a non-physiological blood medium, also occurred. On the basis of their results, the authors submit the hypothesis of the existence of oxytocinase isoenzymes and of the probable presence of several peptidases with overlapping specificity.
The authors studied the splitting dynamics of the synthetic chromogenic substrate (S-benzyl-L-cysteine-p-nitroanilide) specific of serum cystine aminopeptidase, depending on a wide range of pH (from 2.5 to 8.0) by means of an enzymatic serum system of pregnant women and selected animals (sheep, cows, sewer-rats), compared with non-pregnant controls. Examining the form of the enzymatic activity curves of the enzymatic system of women's and animal serum in dependence on pH, the authors revealed a characteristic bell-shaped course of the curve in the serum of pregnant women, as distinct from the sera of animals; the activity of cystine aminopeptidase in cows shows a two-peak course at pH from 3.5 to 4.0 and at pH from 6.5 to 7.0 while other animal species show irregularities with signs of the second peak. It follows from the results of the experiment that the main difference between pregnant and control animals is not the general increase of cystine aminopeptidase but a shift of the occurrence, or an increase of enzymatic activity at the given pH. The highest levels of cystine aminopeptidase were found in the blood sera of sewer-rats and lower in sheep and cows.
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