Aptamer RA36 inhibits of human, rabbit, and rat plasma coagulation activated with thrombin or snake venom coagulases.

RA36 DNA aptamer is a direct anticoagulant prolonging clotting time of human, rabbit, and rat plasma in the thrombin time test. Anticoagulant activity of RA36 is lower than that of recombinant hirudin. During inhibition of human plasma clotting activated with echitox (coagulase from Echis multisquamatus venom), the aptamer presumably binds to meisothrombin exosite I. The sensitivity of human plasma to the aptamer 5-fold surpasses that of rat plasma. Analysis of RA36 binding to coagulase of Agkistrodon halys venom (ancistron) is required for proving the effect of aptamer on polymerization of human fibrinogen.

[Comparative in vitro study of anticoagulant activity of RA36 DNA aptamer in human, rabbit, and rat blood plasma].

DNA aptamer RA36 with a molecular weight of 10000 is direct-acting anticoagulant whose efficacy is lower than that of recombinant hirudin and unfractionated heparin (UFH) in blood clotting time (BCT), activated blood recalcification time (ABRT), recalcification time (RT), prothrombin time (PT), and activated partial thromboplastin time (APTT) tests. The anticoagulant effect of RA36 is comparable with that of UFH in the thrombin time (TT) test, but is lower than the effect of recombinant hirudin. Analysis of the blood and plasma anticoagulant activity during intravenous bolus administration of aptamer RA36 in rabbits and rats is based on the use ABRT (in blood case) and APTT/RT (in plasma case) tests. The range of doses for evaluation of pharmacodynamic parameters of RA36 during intravenous bolus administration in rabbits and rats is 3 - 34 mg/kg and 1 - 27 mg/kg, respectively. Accordingly, designed dose range for humans is 1 -29 mg/kg.

[Identification of the amino acid residues responsible for the reversible photoconversion of the monomeric red fluorescent protein TagRFP protein].

The site-directed mutagenesis of the monomeric red fluorescent protein TagRFP and its variants was performed with the goal of generating reversibly photoactivatable fluorescent proteins. Amino acids at positions 69, 148, 165, 179, and 181 (enumeration according to the green fluorescent protein GFP) were shown to play a key role in the manifestation of the photoactivatable properties. A reversibly photoactivatable red fluorescent protein KFP-HC with excitation and emission maxima at 585 and 615 nm, respectively, was generated. The KFP-HC fluorescent intensity was decreased by 5-10 times under green light (530-560 nm) irradiation (due to the fall of the fluorescence quantum yield) and restored under irradiation with blue light (450-490 nm) or after incubation in the dark (time of half reconstruction of 30 min).

[Signaling function of phagocytic NADPH oxidase: activation of MAP kinase cascades in phagocytosis].

Until recently, the production of reactive oxygen species by NADPH oxidase has been considered only in the context of the oxidative damage to pathogens inside the phagosome. However, homologues of phagocytic NADPH oxidase have been found in almost all cell types, where they produce hydrogen peroxide and thereby regulate the initial intracellular stages of MAP kinase cascades. In the present work, the activation of two MAP kinase cascades, p38 and Erk1/2, during phagocytosis has been studied. It was found that phagocytosis activates both cascades. The activation of Erkl/2 is dependent, and the activation of p38 is not dependent, on the activity of NADPH oxidase. Thus, it can be stated that the activation of MAP kinases in phagocytes during phagocytosis occurs by a mechanism similar to that operating in nonphagocytizing cells, indicating the universality of the function of NADPH oxidases in different cell types.

[Application of the duplex-specific nuclease preference method to the analysis of point mutations in human genes].

A new modification of the single nucleotide polymorphism (SNP) analysis (DSNP, duplex-specific nuclease preference) method using the duplex-specific nuclease from the king crab was proposed. The method was used to study SNPs in the following human genes: kRAS, nRAS, hRAS, and p53, the genes of blood coagulation factor V, methyltetrahydrofolate reductase, prothrombin, and apolipoprotein E and a deletion in the BRCA1 gene. DSNP was shown to be useful for the estimation of the mutant allele content in DNA samples. A system for the simultaneous identification of several adjacent single-nucleotide polymorphisms in the kRAS gene was proposed. The approaches could be used to develop test systems for the detection of SNPs in human genes. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2005, vol. 31, no. 6; see also http://www.maik.ru.

[Biological effect of human erythropoietin in transgenic mice]. / Biologicheskii éffekt éritropoétina cheloveka u transgennykh myshei.

Transgenic mice were obtained inheriting the human erythropoietin gene under the control of viral regulatory elements. The reliable difference in haematocrit, the content of haemoglobin and percentage of reticulocytes in peripheral blood were not revealed. The level of serum erythropoietin in transgenic mice is several fold higher than in control mice. The increased pool of erythroid cells was observed in the bone marrow of transgenic mice, especially of normoblasts (3-fold) and reticulocytes (4,5-fold).