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Biomedical subjects

O V Kazakova

Publications and source records attributed to O V Kazakova.

At least 19 recordsLinked to original sources
PubMed1986

Comparative studies on protein turnover regulations in tumor cells and host tissues: development and analysis of an experimental model.

The protein mass of cells and tissues is determined by the relative rates of protein synthesis (PS) and degradation (PD). A convergent modulation of both PS and PD is operated by many cell types to regulate protein accumulation and thus growth. Transformed and neoplastic cells may show markedly defective PD regulations. Yet even highly-deviated cells such as those of the transplantable Yoshida ascites hepatoma AH-130 cease growth when attaining a conspicuous population size, by operating a combined reduction of PS and acceleration of PD. As in normal cells, PD acceleration is effected through an activation of the acidic-vacuolar (lysosomal) mechanism. AH-130 tumor-bearing rats develop a markedly negative nitrogen balance early after transplantation. Tumor growth involves pronounced perturbations in host body and tissue protein metabolism. Apparently, these changes occur mostly at the level of PD rather than PS, at least in liver and skeletal muscle (gastrocnemius). These observations indicate that either tumor and host cells sense different signals for PD regulations or their thresholds for the same signals are poised differently. This model seems most suitable for further studies to elucidate which signals and mechanisms are involved in these protein metabolic perturbations and possibly, to develop the rationale for adequate corrective strategies.

Animals↗
PubMed1985

Changes in rat liver immunoreactive cathepsin D after cycloheximide.

A rocket immunoelectrophoretic procedure has been developed for the assay of cathepsin D (EC 3.4.23.5) immunoreactive protein, in a 10-100 ng range, directly on crude soluble liver homogenate extracts. By this method, the drop in activity of rat liver cathepsin D effected by repeated doses of cycloheximide, a protein synthesis inhibitor, reflects a parallel change in total enzyme protein content, the specific activity being stable in the course of the treatment. These observations are compatible with the hypothesis that ongoing enzyme degradation, coupled with impaired synthesis, accounts for such a decline of cathepsin D.

Animals↗
PubMed1983

Biosynthesis of amino acids from sucrose and Krebs cycle metabolites by Rhizobium lupini bacteroids.

The possibility of amino acids biosynthesis from sucrose, metabolites of Krebs cycle or glyoxylate and ammonium by intact bacteroids has been studied. The suspension of intact Rhizobium lupini bacteroids in phosphate buffer solution pH 7.8 was shown to catalyse the biosynthesis from sucrose and ammonium of some amino acids, such as alanine, aspartic and glutamic acids, glycine and serine. The yield of alanine and aspartic acid was 2.5-3 times higher than that of other amino acids, which were formed in almost equal quantities. Intact bacteroids were also found to catalyse the biosynthesis of aspartic and glutamic acids, alanine and glycine from ammonium and Krebs cycle metabolites such as fumaric acid (FA), oxaloacetic acid (OAA), pyruvic acid (PA), alpha-ketoglutaric acid (alpha-KGA), malic acid (MA), as well as from glyoxylic acid (GOA). The biosynthesis of aspartic acid from fumaric acid was dominant. Besides that, the suspension of intact bacteroids catalysed transamination of aspartic and glutamic acids, the transamination of aspartic acid being especially intense with alpha-KGA and GOA. Aspartic acid was synthesized most efficiently through the amination of fumaric acid, while glutamic acid was better synthesized through the transamination of aspartic acid with alpha-KGA than through reductive amination of alpha-KGA. The experimental data proved that intact bacteroids possess Krebs cycle enzymes and primary ammonia assimilation enzymes. This enzyme complex permits bacteroids to detoxify ammonia, which they produce using sucrose and metabolites of Krebs cycle as the sources of carbon. The data obtained are of great interest as they prove the importance of bacteroids in the synthesis of amino acids from ammonium which is formed in the course of N2-fixation, and sucrose available from leaves.

Amino Acids↗
PubMed1982

[Hydrolysis of synthetic peptides by group D cathepsins].

The effects of highly purified preparations of cathepsine D from human liver, spleen and some tumours on synthetic hexa- and heptapeptides were studied. The cathepsins were obtained by repeated chromatography on pepstatin-Sepharose with subsequent gel filtration through Sephadex G-100. The peptides tested were structural analogs of pepstatin, a natural inhibitor of carboxylic proteinases. In these analogs the amino acid statin essential for the inhibitory action was substituted for the residues of natural amino acids serine, threonine and glycine. It was shown that the peptides Ac-Val-Leu-Ser-Leu-Thr, Ac-Val-Val-Ser-Leu-Leu-Ser and Ac-Val-Val-Gly-Leu-Leu-Ser are appropriate substrates for cathepsins D. When leucine was substituted for isoleucine, the peptides were virtually resistant to the action of cathepsins D. The cathepsins from normal liver and spleen hydrolyzed only the peptide bonds formed by leucine. Cathepsins from malignant tumours exhibited a broader specificity in comparison with those from normal tissues, producing slight hydrolysis of other bonds.

Amino Acid Sequence↗
PubMed1981

[Inhibition of kininogenase activity of cathepsins D by acid-resistant proteinase inhibitor from rabbit serum].

The inhibitory effect of thermo- and acid-resistant inhibitor of trypsin, chymotrypsin and leukocyte proteinases (TASPI) from rabbit serum on the kininogenase activity of cathepsins D from different organs and tissues (human spleen and liver, chicken liver, spleen leukemic infiltrate from patients with myeloid leukemia) was revealed. The progressive mechanism of TASPI and cathepsins D complexation dependent on time and temperature was revealed. The rate constant of inhibition (ki) of chicken liver cathepsin D by TASPI at 37 degrees was 4,25.10(3)M-1 min-1. It was shown that the kininogenase activity of chicken liver cathepsin D was slightly inhibited by the basic pancreatic trypsin and kallikrein inhibitor from bovine organs (Kunitz type) and by soya bean trypsin inhibitor. The role of TASPI as regulator of cathepsins D activity under pathological conditions accompanied by lysosomal disintegration is discussed.

Animals↗
PubMed1980

[Kininogenase activity of cathepsins D].

The kininogenase activity of highly purified preparations of cathepsins D from human liver and spleen, leukemic infiltrate obtained from patients with myeloic leukemia, and from chicken liver was studied. It was found that pepstatin, a specific inhibitor of carboxylic proteinases, inhibits this activity of cathepsins D. Interaction of chicken liver cathepsin D with human plasma substrate, which is possibly a low molecular weight kininogen (Ks = 1.3.10(-7) M) results in a production of the bradikinin analog methionyl-lysyl-bradikinin. The role of cathepsins D as potent inflammatory agents responsible for the generation of biologically active peptides--mediators of inflammation from the protein substrates including kininogens under desintegration of lysosomes is discussed.

Animals↗
PubMed1979

[Cathepsins D from normal and some human neoplasms].

Cathepsins D were isolated from human liver and spleen, from three malignant tumours (kidney cancer, sarcoma, spleen tumour caused by chronic myeloleucosis) and from one non-malignant tumour (uterine myoma). The isolation procedure involved adsorption on pepstatin-Sepharose and gel-filtration on Sephadex G-100. A comparative study of the properties of these enzymes was carried out. The molecular weights, specific proteolytic activity toward hemoglobin and the synthetic hexapeptide Acetyl-Val-Val-Leu-Ser-Leu-Thr, carbohydrate content and type of dissociation of the molecules into polypeptide fragments during electrophoresis in the presence of DS-Na were determined. All the enzymes under study had molecular weights of about 45 000 except uterine myoma cathepsins (mol. weight 95 000). The latter cathepsin also differed from the other enzymes in its higher carbohydrate content.

Cathepsins↗
PubMed1977

[Study of the carbohydrate component of cathepsin D].

A content of neutral sugars and N-acetyl-glucosamine in homogeneous cathepsin D preparations from a variety of vertebrate organs was determined. A more detailed study of the carbohydrate component was carried out with chicken liver cathepsin D preparation. It was shown that carbohydrates constitute 20% of the molecule of this cathepsin and contain glucosamine (11.6%) and mannose (10%). Removal of the major portion of the carbohydrates by treatment with mixture of glycosidases did not lead to any significant decrease of biological activity. This finding suggests that the carbohydrate component is not essential for the biological activity of the enzyme. Analysis of distribution of carbohydrates in the peptides of the trypsin hydrolyzate of cathepsin D allows conclusion that the enzyme molecule has several carbohydrate chains attached to different sites of the molecule.

Animals↗
PubMed1975

Some properties of cathepsins chemically fixed to carriers.

An insoluble preparation of rat liver cathepsin D was obtained by coupling the enzyme to Enzacryl Polyacetal (EPA-cathepsin) and to CNBr-activated Sepharose 4B. EPA-cathepsin was active toward the synthetic hexapeptides (Gly-Phe-Leu)2 and did not split hemoglobin. The optimum pH of splitting was displaced upward by 1.5 units to pH 5.0. The enzyme exhibited maximum activity at 60 degrees C. No appreciable loss of activity was seen on storage of the enzyme for 4 months or after repeated use of the preparations. Coupling of rat liver cathepsin D to activated Sepharose gave preparations active towards both protein and synthetic substrates. The preparations were totally inactive in acid media and exhibited maximum activity at pH 7.0, that is, under physiological conditions. Optimum temperature was 65 degrees. The specific activity of the preparations (pH 7.0, 65 degrees) was 60-110 percent that of the free enzyme in acid media. Proteolytic activity of the Sepharose-coupled cathepsin D was not inhibited by pepstatin, whereas that of the free enzyme was fully inhibited by this reagent. A sarcoma cathepsin, similar in some of its properties to the rat liver enzyme, was also coupled to CNBr-activated Sepharose 4B. The preparation split protein substrates at pH 7.0 and possessed enhanced thermostability. The enzymes fixed on Sepharose showed increased stability.

Acetals↗
PubMedDate not supplied

[Isolation of cathepsins D by affinity chromatography].

The paper deals with the isolation of cathepsin D from rat liver, chicken liver and bovine spleen by affinity chromatography. The synthesis of the adsorbent was performed using the competitive inhibitor of cathepsins D and pepsin pepstatin and activated Sepharose. Application of a pepstatin-Sepharose column allows obtaining a highly active and purified enzyme in a short period of time.

Animals↗
PubMedDate not supplied

[Assessment of autonomic nervous system function in patients with generalized periodontitis].

The 56 patients with different stages of generalized periodontitis were investigated using a simplified A. M. Veĭn (1971) routine. The clear preponderance of sympathetic autonomic responses over the parasympathetic ones was evident. Besides, a compensatory activation of parasympathetic nervous system was reflected in inversion responses to clinostatic and Ashner tests.

Adult↗