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Biomedical subjects

A V Timofeeva

Publications and source records attributed to A V Timofeeva.

9 recordsLinked to original sources
PubMed2000

Size distribution of the urokinase mRNA decay intermediates in different tissues and cell lines.

Many genes, particularly those encoding the products participating in the regulation of transcription, replication and tissue remodeling, produce short-lived mRNA. It has been commonly accepted that once mRNA is disintegrated, the degradation process is so rapid that the decay intermediates cannot be detected. In the present study we verified this postulate and focused our attention on the quantification of the decay products of the urokinase-type plasminogen activator (uPA) mRNA that belongs to short-lived mRNAs. Using a previously described modified quantitative RT-PCR method, we have shown that intact uPA mRNA coexists in normal human tissues, Jurkat and 5637 cells with a great abundance of its degradation products. The uPA mRNA decay products were not detected in T24P cells. The content of intact uPA mRNA in normal tissues was as low as 5% of the total amount of its poly(A)(+) fraction. The size distribution of the mRNA decay products suggests that the mRNA is digested by exonucleases or/and non-specific endonuclease with cut sites evenly distributed along the mRNA chain. Different decay degrees were demonstrated for subpopulation of the uPA mRNA molecules with intact 3' and 5' ends.

Blotting, Northern↗
PubMed1993

[The effect of fraxiparin on thrombocytic-vascular hemostasis in patients with unstable stenocardia].

Clinical examination of 25 males with new-onset and progressive angina pectoris resistant to inpatient combined antianginal treatment versus 15 healthy males established hyperfunction of the platelets in low antithrombogenic activity of the vascular walls in patients with unstable angina pectoris. A 5-day course of fraxiparin resulted in a trend to a decrease in ADP-induced platelet aggregation and in the level of platelet factor IV. The endothelium recovered normal antiaggregation and fibrinolytic properties. This may underlie the drug efficacy against unstable angina pectoris.

Adult↗
PubMed1990

[Willebrand's factor, functional activity of blood platelets and antiaggregation activity of the vascular wall in ischemic heart disease].

Fifty coronary male patients aged 34 to 63 (the mean age 46) and 32 normal male subjects aged 18 to 32 (mean age 23) were examined for the levels of Willebrand's factor, induced platelet aggregation, beta-thromboglobulin, thromboxane, prostacyclin levels, and vascular wall antiaggregation activity (by the cuff test). Basing on literature data and their own findings the authors come to a conclusion that elevated plasma concentration of Willebrand's factor combined with increased functional activity of platelets and reduced vascular wall antiaggregation activity is the key factor in the pathogenesis of atherosclerosis development and progress.

Adult↗
PubMedDate not supplied

[A kinetic model of the cleavage of permutational variants of the antigenomic HDV-ribozyme].

The kinetic characteristics have been studied for noncircularly permuted variants of the human hepatitis delta virus (HDV) antigenomic ribozyme to find out the cause of the two-phase kinetics of the self-cleavage reaction. Different ways of reaction initiation, suboptimal conditions, and jumpwise changes of reaction conditions have been used, and the temperature dependences have been studied. A correlation has been shown between the apparent kinetic constant of the first reaction phase and the portion of the ribozyme molecules that self-cleaved during the first phase. Partial restoration of the initial reaction characteristics has been shown by the reinitiation of reaction being stopped after completing the first phase. On the basis of all the data obtained, a scheme of the self-cleavage reaction has been proposed including: (i) activation of the ribozyme with energy of 40-50 kcal/mol and a characteristic time of several deciminutes under optimal reaction conditions; (ii) fast and reversible reaction of the phosphodiester bond cleavage; (iii) reaction leading to isomerization of the 3',5'-phosphodiester bond to the 2',5' bond in the self-cleavage site with a characteristic activation time of tens of minutes; and (iv) practically irreversible conformational change leading to fixation of the cleavage by immobilization of the 5'-terminal nucleotide of the product in the center of the formed structure and displacement of the 3'-terminal nucleotide to the periphery. The latter process has a characteristic time of tens of minutes and a low activation energy.

Base Sequence↗