PubMed Health⌕ Search

Biomedical subjects

T N Platonova

Publications and source records attributed to T N Platonova.

17 recordsLinked to original sources
PubMed1988

The cleavage of beta-chain in bovine fibrinogen DH fragment (95 kDa) leads to a significant increase in its anticlotting activity.

It is shown that in the presence of Ca2+ plasmin converts bovine fibrinogen fragment DH (95 kDa) into DLA fragment by the cleavage of its beta-chain Arg372-Thr373 bond. DLA fragment consists of two components (82 and 12 kDa) held together by non-covalent bonds and has 3.5-fold higher anticlotting activity than DH fragment. The DH to DLA fragment conversion leads to the destabilization of thermolabile domains of the latter without the loss of their compact structure. The results obtained show that the activation of DH fragment by the cleavage of its Arg372-Thr373 bond bears some resemblance to the general activation of proenzyme into enzyme.

Amino Acid Sequence↗
PubMed1983

[Differences between the complexes formed by monomeric fibrin with fragment D and dimer D].

The paper is concerned with studies in formation of monomeric fibrin (fm) complexes with fragment D (D) of fibrinogen and dimer D (DD) of stabilized fibrin. The complexes are shown to be essentially different. The fm-D complexes are unstable, their composition is a function of D concentration in the mixture, the ultimate molar D/fm ratio is equal to 3. The fm-DD complexes are quite stable, their composition is constant: the molar DD/fm ratio is equal to 1. In mixtures containing fm, DD and different amounts of D complexes of different composition are formed but the total number of D-units in them approaches 3. A model is suggested showing interaction of fm molecules in protofibril formation with allowance for the retention of binding centres which provide the lateral link between protofibrils.

Animals↗
PubMed1982

[Use of affinity chromatography for the purification of specific endonuclease Eco RI and Bg1 II].

The highly active preparations of specific endonucleases Eco RI and Bgl II were purified by affinity chromatography from E. coli and Bacillus globiggii cells, respectively. The isolation and purification procedures included cell disruption by ultrasonication, ultracentrifugation and chromatography. Blue dextrane-Sepharose, folate-Sepharose and phenyl-Sepharose were used as affinity adsorbents. The optimal conditions for the adsorption and elution of the endonucleases excluding intermediate steps of dialysis and concentration were selected. A high degree of purification was achieved by a consecutive use of adsorbents with different ligands. The purified enzyme does not contain non-specific nucleases or phosphatases, is sufficiently concentrated and can be used for specific hydrolysis of DNA.

Bacillus↗
PubMed1980

[Inhibition of fibrin assembly by fragment D and its dimer derived from fibrinogen and stabilized fibrin. Evidence for the two-step type of inhibition].

The influence of purified fragments D and DD on fibrin monomer polymerization has been studied. When applied separately, DD is less strong an inhibitor than D. An addition of small amounts of DD to the reaction mixtures containing D does not change the inhibitory effect, when the concentration of the latter fragment is low. At high concentrations of D the contribution of DD becomes more pronounced. Small amounts of D added to DD-containing systems strongly enhances the inhibition. These properties of the D--DD mixtures are unpredictable and puzzling; they contradict the generally accepted view that the specific inhibitors of fibrin polymerization, to which D and DD belong, act in a simple competitive way. The whole incomprehensible situation may be clarified in terms of a hypothesis on a two-step mechanism of inhibition. It is assumed that at the first (preliminary) step of the inhibitor effect DD is less competent than D, whereas at the second step DD possessing a high affinity for the fibrin monomer, functions as the most effective competitive inhibitor.

Animals↗
PubMedDate not supplied

[The prevention of HIV infection in the army and navy].

In the course of 5 years 121 foreign and 13 Soviet military servicemen showed HIV infection; seven of them (officers and warrant officers) are still in service. As distinct from WHO requirements symptomless virus carriers are also registered. Infected servicemen constitute 1.5% from the total number of infected in the country.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

[Antithrombin III. Functional role and methods of determination (review)].

Antithrombin III (AT III) is the most important inhibitor of thrombin and other serine proteinases in the system of blood coagulation. AT III not only removes the excess of thrombin from blood but it inhibits the enzyme synthesis. AT III became functionally active in presence of heparin, which operates as a catalyst and accelerates significantly the formation of inactive complexes between AT III and proteinases, which usually developed slowly in absence of the activator. AT III and heparin cofactor are synonyms and designate the same substance. Modern procedures for estimation of AT III in blood plasma are reviewed.

Antithrombin III↗
PubMedDate not supplied

[An analysis of a disorder in the fibrin-forming phase in virtually healthy middle-aged and elderly subjects by using the ancistron test].

Damages in the fibrin-formation phase initiated by activation of the blood coagulation system and fibrinolysis and promoted by interaction between fibrinogen and its derivatives (dissolved fibrinogen, products of fibrin and fibrinogen lysis) and by the presence of various blood coagulation inhibitors were found in 34% of practically sound old people and in 47% of people of senile age. It is shown very significant to apply the "ancistrone time" test developed on the basis of enzyme ancistrone-H isolated from the venom of snake Agkistrodon halys halys for estimating the fibrin-formation phase both on the model system and in practically sound people of old and senile age. The ancistrone test permits rapidly (for 30-60s) obtaining qualitative and quantitative characteristic of the fibrinogen level in the blood plasma, of the products of fibrin and fibrinogen lysis, of the blood coagulation inhibitors.

Aged↗
PubMedDate not supplied

[The determination of fibrinogen in the blood plasma during heparin therapy].

A new method is suggested for blood plasma fibrinogen measurements, making use of ancystron-N thrombin-like enzyme, isolated from common viper venom. Comparative studies have demonstrated the possibility of using the new test for plasma fibrinogen determination in heparin-containing or intact blood.

Agkistrodon↗
PubMedDate not supplied

[Determination of fibrinogen content in human blood plasma using thrombin-like enzyme of ancistron N and analysis of hemostasis under presence of blood coagulation inhibitors].

The cases of non-coagulation or only partial coagulation of blood plasma fibrinogen under the effect of thrombin have been revealed while examining the homeostasis-state in practically healthy elderly and old people and those with hypertonic disease. These cases have been analyzed. It is shown that the suggested method of fibrinogen determination in blood plasma using thrombin-like enzyme ancistrone-H extracted from venom of snakes (Agkistrodon halys halys) permits determining the fibrinogen content in blood plasma even in the cases connected with the presence of circulating coagulation inhibitors in plasma. The determination is not hindered by the introduction of exogenous heparin, including low-molecular heparins of the fraxiparin type.

Aged↗
PubMedDate not supplied

[Determination of the general prothrombin level and detection of its functionally inactive forms using the enzyme ecamulin purified from Echis multisquamatus venom].

The method for determination of the general prothrombin level and detection of its inactive forms (prothrombin-1, decarboxylated prothrombin, etc.) has been worked out. Enzyme ecamulin was purified from the venom of Echis multisquamatus. Ecamulin test was used for plasma of practically healthy people and patients with hypertension. The results obtained proved that this test is informative and precise. Comparison of two tests, prothrombin and ecamulin ones, permits characterizing the state of blood coagulation and finding functionally inactive prothrombin forms which are the markers of some pathological states.

Adult↗
PubMedDate not supplied

[Comprehensive laboratory diagnosis of intravascular blood coagulation syndrome in late gestosis].

A chronic form of intravascular blood coagulation (the DIC syndrome) is an obligatory pathogenetic mechanism in the organism of pregnant women with late gestoses. In order to find the DIC-syndrome and to provide urgent protective measures comprehensive laboratory diagnostics of the hemostatic pathologies is necessary. Analysis of clinician data has shown an optimal quantity and sequence of tests, among which some are traditional and several have been worked out by the authors. This approach can be recommended for corresponding medical institutions as such that provides obtaining exact and informative data about the state of blood coagulation with minimal amounts of human plasma.

Adult↗