HEMATOPOIETIC PROGENITORS CELLS IN PERIPHERAL BLOOD OF BALB/C MICE UNDER IONIZING RADIATION ACTION IN SUBLETHAL DOSE.

Objective: determination of the content of hematopoietic progenitor cells circulating in peripheral blood of Balb/Cmice, under ionizing radiation action in sublethal dose, at different periods after the irradiation, using cell culturein diffusion chambers in vivo.

Methods: Peripheral blood smears of Balb/C mice were prepared and studied, its cellular composition was determined, as well as by cultivation of peripheral blood cells in diffusion chambers in vivo their colony-forming efficien-cy was determined on the 0th, 5th, and 30th day after external irradiation in sublethal dose 5.85 Gy.

ANALYSIS OF THE INFLUENCE OF PROLONGED IRRADIATION ON HEMATOPOIETIC PROGENITOR CELLS IN GEL DIFFUSION CHAMBERS USING MATHEMATICAL MODELLING.

Objective: determining of the functional activity of mice bone marrow hematopoietic progenitor cells, cultivated in gel diffusion chambers, on the stages of hematopoiesis recovery after their prolonged irradiation in the lethal dose in a comparative aspect with the method of colony forming in spleen using mathematical model.

Materials And Methods: The method of cell cultivation in gel diffusion chambers, cytological methods, mathematical modeling, and statistical methods of research were used. Bone marrow samples extracted from the femur of mice irradiated with a total dose of 8 Gy with a power 0.

HUMANIZED MODEL OF ISOLATED SUSPENSION CULTIVATION OF HEMATOPOIETIC PROGENITOR CELLS FOR THE INVESTIGATION OF IONIZING RADIATION INFLUENCE IN VIVO.

Objective: development of the humanized system for cells cultivation outside the human organism (human-mouse)and investigation of the influence of ionizing radiation in increasing doses on the colony-forming ability ofhematopoietic progenitor cells.

Materials And Methods: Bone marrow samples of individuals without blood system diseases were cultivated in geldiffusion chambers with semi-solid agar in the abdominal cavity of CBA mice exposed to ionizing radiation action.Cell aggregates, which were obtained in the culture of diffusion chambers in vivo, were counted and colony-formingefficiency of bone marrow cells was determined.

COMPARATIVE MATHEMATICAL ANALYSIS OF COLONY-FORMING ABILITYOF THE BONE MARROW OF MICE LETHALLY AND NON-LETHALLY IRRADIATED WITH EQUAL DOSE RATE INTENSITY.

Objective: To perform comparative analysis of the characteristics of population functioning process of mice bonemarrow colony-forming units after their prolonged irradiation in lethal and non-lethal doses with equal dose rateintensity with the aid of mathematical model.

Materials And Methods: Assigned task is solved by means of mathematical model of alterations in the number ofbone marrow colony-forming units after continuous irradiation, described in previous works, with the use of experimental results of K. S.

ASSESSMENT OF RADIOPROTECTIVE ACTION OF BASIDIOMYCOTIC MELANIN PIGMENTS ON THE HEMATOPOIETIC SYSTEM OF Balb/C MICE UNDER EXPOSURE TO IONIZING RADIATION IN SUBLETHAL DOSE.

Objective: Assessment of radioprotective action of basidiomycotic melanin pigments on hematopoietic stem and progenitor bone marrow cells of Balb/C mice in case of exposure to ionizing radiation in sublethal dose.

Materials And Methods: Using original method of cultivation in gel diffusion chambers in vivo of bone marrow cells of Balb/C mice we investigated the colony-forming efficiency of hematopoietic progenitor cells of the ani- mals, which were exposed to ionizing radiation action in sublethal dose, in case of treatment with melanin pig- ments solution of basidiomycotic fungi as radioprotector.

Results And Conclusions: Investigation of functional activity of bone marrow progenitor cells of Balb/C mice allowed assessing their hematopoiesis state in case of ionizing radiation action, as well as in case of previous treat- ment of the animals with the solution of melanin pigments as radioprotector.

MATHEMATICAL ANALYSIS OF FUNCTIONAL PROPERTIES OF MICE BONE MARROW IN THE INITIAL PHASE OF ACUTE FRACTIONATED IRRADIATION.

Objective: to determine the quantitative characteristics of population functioning of mice bone marrow colony-forming units during seven days of acute fractionated irradiation.

Materials And Methods: Assigned task is solved by means of described in works R. V.

Mesenchymal stem and progenitor cells of rats' bone marrow under chronic action of ionizing radiation.

Unlabelled: Under the influence of ionizing radiation on hematopoietic system, the level of its injury is determined not only by the radiosensitivity of hematopoietic stem cells, but also by radiation induced changes in microenvironment func tioning, in particular, mesenchymal stem cells as its components.

Objective: to define functioning characteristics of mesenchymal stem and progenitor cells of rats' bone marrow under prolonged action of ionizing radiation as a result of 90Sr incorporation.

Materials And Methods: We applied the model of Wistar rats' internal irradiation with 90Sr radionuclide and per formed the in vitro cultivation of their bone marrow mesenchymal cells.

Dynamic and Energetic Signatures of Adenine Tracts in a rA-dT RNA-DNA Hybrid and in Homologous RNA-DNA, RNA-RNA, and DNA-DNA Double Helices.

Nuclear magnetic resonance spectroscopy and proton exchange are being used to characterize the opening reactions of individual base pairs in the RNA-DNA hybrid 5'-rGCGAUAAAAAGGCC-3'/5'-dGGCCTTTTTATCGC-3'. The hybrid contains a central tract of five rA-dT base pairs. The rates and the equilibrium constant of the opening reaction for each base pair are determined from the dependence of the exchange rates of imino protons on ammonia concentration, at 10 °C.

Circulating hematopoietic progenitor cells in patients affected by Chornobyl accident.

Unlabelled: High radiation sensitivity of stem cells and their ability to accumulate sublethal radiation damage provides the basis for investigation of hematopoietic progenitors using in vivo culture methodology. Unique samples of peripheral blood and bone marrow were derived from the patients affected by Chornobyl accident during liquidation campaign.

Aim: To investigate functional activity of circulating hematopoietic progenitor cells from peripheral blood and bone marrow of cleanup workers in early and remote periods after the accident at Chornobyl nuclear power plant (CNPP).

Pattern changes in quantitative and qualitative markers of hematopoietic stem cells during acute and chronic exposure to 90Sr isotope in cell culture.

Objective: The objective of our research was investigation of the hematopoietic system of laboratory rats under the influence of acute and chronic internal exposure to 90Sr isotope.

Materials And Methods: To study the condition of stem cells and their immediate progenitors we implemented cell culture methodology in vivo in gel diffusion capsules with subsequent analysis of the colonies and clusters.

Results: On the basis of experiments it was established that long-term effects of incorporated 90Sr isotope leads to significant disturbances in the hematopoietic system and in particular, revealing changes in hematological parameters of irradiated animals such as the appearance of circulating progenitor cells in peripheral blood, reducing the colony-forming efficiency of the bone marrow derived progenitor cells, as well as quantitative and qualitative changes in the clones.

Character of interaction between irradiated and non-irradiated cells in culture in diffusion chambers in vivo.

Objective: Current investigation is devoted to determination of interaction type between the non-irradiated murine bone-marrow cells and irradiated microenvironment in cell culture in diffusion chambers in vivo.

Materials And Methods: To study the characteristics of interaction between the cells we implemented an original cultivation model with bone-marrow cells of intact Balb/c mice inserted in the diffusion chambers in peritoneum of irradiated animals (it provided the access of nutrients and signaling molecules from outside).

Results: As a result of investigations performed, we have determined the direct influence of microenvironment factors of irradiated mice organism on the non-irradiated bone-marrow cells.

Site-resolved structural energetics of the T7 concatemer junction.

The concatemer junction is a conserved sequence of 8 bp, which is strategically located at the junction between the head-to-tail repeats of genomic DNA in T7 and related bacteriophages. The RNA polymerase pauses at this site to recruit the machinery necessary for cleavage of the concatemer into single genome DNA. During pausing, the transcription bubble collapses and the transcription RNA-DNA hybrid is shortened to only 3 bp.

Opening dynamics of 8-oxoguanine in DNA.

8-oxoguanine is a major lesion of genomic DNA that results from oxidation of guanine by reactive oxygen species. The repair of this lesion is initiated by 8-oxoguanine glycosylases, which excise the damaged base by "flipping" it outside the DNA double helix. The molecular mechanisms involved in the specific recognition of the damaged base by the enzyme are not yet fully understood.

Enhanced base-pair opening in the adenine tract of a RNA double helix.

Proton exchange and nuclear magnetic resonance spectroscopy are being used to characterize the kinetics and energetics of base-pair opening in two nucleic acid double helices. One is the RNA duplex 5'-r(GCGAUAAAAAGGCC)-3'/5'-r(GGCCUUUUUAUCGC)-3', which contains a central tract of five AU base pairs. The other is the homologous DNA duplex with a central tract of five AT base pairs.

Structural energetics of the adenine tract from an intrinsic transcription terminator.

Intrinsic transcription termination sites generally contain a tract of adenines in the DNA template that yields a tract of uracils at the 3' end of the nascent RNA. To understand how this base sequence contributes to termination of transcription, we have investigated two nucleic acid structures. The first is the RNA-DNA hybrid that contains the uracil tract 5'-rUUUUUAU-3' from the tR2 intrinsic terminator of bacteriophage lambda.

Dynamics and stability of individual base pairs in two homologous RNA-DNA hybrids.

Nuclear magnetic resonance spectroscopy and proton exchange have been used to characterize two RNA-DNA hybrids from the tR2 intrinsic transcription terminator site of phage lambda. The hybrids have the same base sequence [5'-GGCGCAGGCC(T/U)(T/U)CC-3'/5'-GGAAGGCC(T/U)GCGCC-3'] but differ from each other by an interchange of DNA and RNA strands. The opening of single base pairs in the two hybrids is characterized by measuring the rates of exchange of imino protons with solvent protons as a function of the concentration of a proton acceptor (ammonia base) at 10 degrees C.

Influence of magnesium ions on spontaneous opening of DNA base pairs.

A large amount of experimental evidence is available for the effects of magnesium ions on the structure and the stability of the DNA double helix. Less is known, however, on how these ions affect the dynamics of the molecule and the stability of each individual base pair. The present work addresses these questions by a study of the DNA duplex [dCGCAGATCTGCG]2, and its interactions with magnesium ions using nuclear magnetic resonance (NMR) spectroscopy and proton exchange.

Probing the role of hydrogen bonds in the stability of base pairs in double-helical DNA.

Aromatic stacking and hydrogen bonding between nucleobases are two of the key interactions responsible for stabilization of DNA double-helical structures. The present work aims at defining the specific contributions of these interactions to the stability of individual base pairs in DNA. The two DNA double helices investigated are formed, respectively, by the palindromic base sequences 5'-dCCAACGTTGG-3' and 5'-dCGCAGATCTGCG-3'.

Structural energetics and base-pair opening dynamics in sarcin-ricin domain RNA.

The sarcin-ricin domain is a universal element of the RNA from the large ribosomal subunit. The domain is part of the binding site for elongation factors and is specifically cleaved by the toxins alpha-sarcin and ricin. In this work, we have mapped the energetics and dynamics of individual structural motifs in a 29-mer RNA oligomer containing the sarcin-ricin domain.

Specific interactions of divalent metal ions with a DNA duplex containing the d(CA)n/(GT)n tandem repeat.

Divalent metal ions are essential for maintaining functional states of the DNA molecule. Their participation in DNA structure is modulated by the base sequence and varies depending on the nature of the ion. The present investigation addresses the interaction of Ca2+ ions with a tandem repeat of two CA dinucleotides, (CA)2/(TG)2.

A nuclear magnetic resonance investigation of the energetics of basepair opening pathways in DNA.

The opening of basepairs plays a key role in DNA replication and transcription, and in the action of DNA repair and modification enzymes. In this article, we have used proton exchange to define the energetics of the pathways for basepair opening in two DNA 17-mer duplexes. The rates of exchange of imino protons with solvent protons were measured by NMR spectroscopy for each DNA duplex, as a function of the concentration of exchange catalyst and of temperature.

Base pair opening in three DNA-unwinding elements.

DNA-unwinding elements are specific base sequences that are located in the origin of DNA replication where they provide the start point for strand separation and unwinding of the DNA double helix. In the present work we have obtained the first characterization of the opening of individual base pairs in DNA-unwinding elements. The three DNA molecules investigated reproduce the 13-mer DNA-unwinding elements present in the Escherichia coli chromosome.

Sequence-dependence of the energetics of opening of at basepairs in DNA.

Proton exchange and nuclear magnetic resonance spectroscopy are being used to characterize the energetics of opening of AT/TA basepairs in the DNA dodecamer 5'-d(GCTATAAAAGGG)-3'/5'-d(CCCTTTTATAGC)-3'. The dodecamer contains the TATA box of the adenovirus major late promoter. The equilibrium constants for opening of each basepair are measured from the dependence of the exchange rates of imino protons on ammonia concentration.

Site-resolved stabilization of a DNA triple helix by magnesium ions.

Proton exchange and NMR spectroscopy have been used to define the effects of Mg2+ ions upon the stability of individual base pairs in the intramolecular parallel triple helix formed by the DNA oligonucleotide d(GAAGAGGTTTTTCCTCTTCTTTTTCTTCTCC). The rates of exchange of individual Watson-Crick and Hoogsteen imino protons in the DNA triple helix were measured in the absence and in the presence of Mg2+ ions. The results reveal that Mg2+ lowers the exchange rates of most imino protons in the structure by stabilizing the corresponding base pairs in their native closed conformation.