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Biomedical subjects

T A Smirnova

Publications and source records attributed to T A Smirnova.

At least 55 records · Page 3Linked to original sources
PubMed1982

[Changes in the myocardium in the early stages of chronic kidney failure].

The functional state of the myocardium was studied in 45 white Wistar rats in the early stages of chronic renal insufficiency. After resection of 4/6 of the renal parenchyma the initial stage of chronic renal insufficiency was created with the urea level in blood serum 7.0-10.0 mmol/l with normal content of electrolytes (duration of observation lasting 1.3 to 6 months). Towards the 3rd month myocardial hypertrophy developed in animals with statistically significant increase of the cardiac mass by 18-20%, not related to enhancement of haemodynamic load on the heart. Arterial pressure remains normal. Hypertrophy of the myocardium as shown by histochemistry was accompanied by increase of energy and protein metabolism, carbohydrates decreased simultaneously due to the decrease of myocardium tolerance to glucose.

Animals↗
PubMed1981

[Nucleomeric organization of chromatin].

Chromatin in the nuclei fixed in tissue and in the nuclei isolated by low ionic strength solutions in the presence of Mg2+ is represented by globular (nucleomeric) fibrils, 20-25 nm in diameter. The staphylococcal or endogenous nuclear nuclease splits the chromatin fibrils resulting in fragments corresponding to nucleomers and their multimers. Upon removal of firmly bound Mg2+ the nucleomers unfold to form chains consisting of 4-6-8 nucleosomes. Mild hydrolysis of nuclear chromatin by staphylococcal nuclease results in a split-off of mono-, di- and trimers of nucleomers sedimenting in a sucrose density gradient in the presence of EDTA as particles with the sedimentation coefficients of 37, 47 and 55S, respectively. The sedimentation coefficient for the mononucleomer in a sucrose density gradient with MgCl2 is 45S. Determination of the length of DNA fragments of chromatin split-off by staphylococcal nuclease showed that the nucleomer consists of 8 nucleosomes, while the dimer and trimer of the nucleomer consists of 14-16 and 21-24 nucleosomes, respectively. The nucleomeric monomer undergoes structural transition from the compact (45S) to the "loose" state (37S) after removal of Mg2+. This transition is completely reversible, when the nucleomer contains histone H1. The removal of the latter or dialysis of the nucleomer against EDTA in low ionic strength solutions results in a complete unfolding of the nucleomer into a nucleosomal chain fragment. A model for the nucleomer fibril structure in which the helical organization of the nucleosomal chain in the nucleomer (2 turns with 4 nucleosomes in each) is alternated with the impaired helical bonds between the nucleomers is discussed. The functional significance of the nucleomeric organization of chromatin may be an additional restriction of the site-specific recognition of DNA in chromatin with the possibility of local (at the level of one nucleomer) changes in chromatin conformation excluding this restriction.

Animals↗
PubMed1981

[Limited accessibility of DNA methylation sites for bacterial methylases M. Eco RII and M.Eco dam in chromatin at different levels of organization].

The bacterial methylases M. Eco RII and M. Eco dam can methylate DNA in rat liver chromatin to form the 5-methylcytosine (m5C) and N6-methyladenine (m6A) residues, respectively. The CH3-accepting capacity of DNA in chromatin (mono- and dinucleosomes, mono- and dinucleomers) is 15 - 30 times less than that of free total DNA in rat liver. Such a low level of DNA methylation in chromatin in vitro suggests that the accessibility and recognition of methylation sites by DNA-methylases are decreased in comparison with free DNA both in the core-particle DNA and in the internucleosomal DNA. The degree of DNA methylation in chromatin particles depends on the ionic strength and Mg2+; when the former is decreased from 0.515 down to 0.176, the DNA methylation by both enzymes is increased 2-fold. An addition of Mg2+ (1 - 2 mM) decreases the CH3-accepting capacity of nucleomeric DNA, that of nucleosomal DNA remains unchanged. Thus, the accessibility of DNA for methylases is variable depending on the conformational changes of chromatin. The values of the m6A to m5C ratio for free and nucleosomal DNAs formed by methylation with a methylation of nucleomeric DNA, i. e. 1.01, 0.92 and 0.51, respectively. As Mg/4 concentration rises, the m6A/m5C ratio for nucleosomal and nucleomeric DNA is increased. It seems therefore that at different levels of organization and upon certain conformation changes the number and, probably, the nature of exposed DNA methylation sites in chromatin are different. Bacterial DNA-methylases can be used as an effective probe for a fine analysis of chromatin ultrastructure, in particular at its different functional states.

Animals↗
PubMed1979

[Participation of glucocorticoids in development and provisions for work capacity].

Physical working capacity of the adrenalectomized Wistar rats can be augmented to some extent by training. This is not accompanied by increased unspecific resistance or augmented content of liver glycogen. The trained adrenalectomized rats revealed heart hypertrophy and increased activity of Mg2+-activated actomyosine ATPase in myocardium. After the training the physical worcing capacity was lower in adrenalectomized rats than in thyroidectomized ones. The 5-day administration of hydrocortisone failed to increase swimming time in adrenalectomized rats provided a high dose of progesterone was injected simultaneously. This can be due to the competition between progesterone and glucocorticoids for the glucocorticoid cytoplasmic receptor sites. The data obtained suggest that the effect of glucocorticoids on the physical working capacity is associated with their action on the adaptive protein synthesis.

Adrenal Glands↗
PubMed1978

[Morphological characteristics of Nocardia asteroides].

Morphology--by growth phases-- was studied in the N. asteroides strain isolated from cows suffering from mastitis in Cuba. During the growth N. asteroides culture underwent a number of morphological cyclic changes; definite morphology was typical for each growth phase. There was a similarity between the structure of the surface N. asteroides and mycobacteria; cyclic changes in the structure of the membranes in nocardia were also shown.

Culture Media↗
PubMed1978

[Antibacterial activity and bacteriophages of Bacillus pumilus].

Inducable defective phages analogous to those in Bac. subtilis were found in 5 strains of Bac. pumilus, 3 of which possessed antibacterial activity. A moderate bacteriophage was also induced in addition to the defective phage in strain ATCC 12140 not producing the antibiotic. It was found that the antibacterial activity was not associated with the presence of phages in the cultures. The data on the electron microscopic investigations are presented.

Anti-Bacterial Agents↗
PubMed1977

[Vitamin C and B1 allowance in various diseases of the gastrointestinal tract].

In 92 patients with various chronic affections of the gastro-intestinal tract vitamins C and B1 content in the blood and urine was measured. As controls 17 healthy persons were examined. Patients with gastro-intestinal affections were found to show a statistically significant fall of the vitamins C and B1 level in the blood and urine at all seasons of the year (winter, spring, summer and fall). But their decline is most intensive with exacerbation of the ailment and then the presence of the pain syndrome is attended by a steeper drop in the level of these vitamins. A course-wise parenteral administration of the vitamins C and B1 results in their statistically significant rise in the blood and urine, their level, however, remaining below that in healthy persons.

Adolescent↗