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Biomedical subjects

V V Kravchenko

Publications and source records attributed to V V Kravchenko.

70 records · Page 4Linked to original sources
PubMedDate not supplied

[How does environment modify the spatial structure of Dictyostelium discoideum population].

The transformation of the spatial structure of a Dictyostelium discoideum population in response to environmental changes induced by this population was investigated. A comparative analysis of the spatial and temporal characteristics of the D. discoideum colony is given for two cases: (a) when the colony is cultivated on a bacterial lawn, i.e. under conditions close to natural, and (b) in the absence of the bacterial lawn when the colony grows on the nutrient substrate enriched with folic acid. It is shown that the environmental changes induced by cell metabolism modify the spatial structure of the D. discoideum population first, the rate of population propagation falls drastically, which correlates with a decrease in the substrate pH; second, the spatial redistribution of the D. discoideum cell density correlates with the redistribution of folic acid in the substrate. The mechanism of the environment impact on the D. discoideum colony transformation is discussed.

Agar↗
PubMedDate not supplied

[The mechanism of formation of Liesegang structures around Dictyostelium discoideum].

A theoretical study of the phenomenon of Liesegang structure formation induced by the Dictyostelium discoideum population in a medium containing folic acid was carried out. Using a "reaction-diffusion" model proposed in this work, it was shown that the formation of Liesegang structures around the Dictyostelium discoideum population depends on two competing processes: (a) inactivation of folic acid by vegetative amoebae and (b) the chemical reaction of folic acid with the products of amoeba metabolism, which results in the formation of insoluble sediment. The dependence of the model solutions on the geometric and functional parameters was studied. The results are in good agreement with experimental data.

Animals↗
PubMedDate not supplied

[Chemoattractants of Distyostelium discoideum (Protozoa: Sarcomastigophora, Eumycetozoa)].

The authors summarize data on interaction of protozoan Dictyostelium discoideum with folia acid and cyclic adenozinmonophosphate as chemoattractants. These substances play role of antagonists in the life cycle of Dictyostelium discoideum: one disperses cells in space and another gathers them into groups forming and organism. Analysis of interaction between Dictyostelium discoideum and environment allows to reveal that Deictyosteliceae has unique mechanism of adaptation of shortage of feeding resource--forming of multicellular organism with functional differentiation of cells. This mechanism could be found at different hierarchical levels of living organisms.

Adaptation, Physiological↗
PubMedDate not supplied

[Using AELTIS-synchro-02 device in the therapy of chronic bacterial prostatitis].

The treatment of chronic bacterial prostatitis combined antibacterial drugs and physiotherapy (low-energy laser radiation, electrostimulation of the prostate). Treatment of chronic bacterial prostatitis with medication and complex two-channel bio-synchronized electrolaser therapy with application of the unit AELTIS-synchro-02 raises efficacy of treatment with chronic bacterial prostatitis due to combined effect of antibacterial drugs and bacteriostatic and immunomodulating actions of the physical factors applied. These normalize microcirculation in the region of the prostatic gland, improve a draining function of the prostatic ducts, allows achievement of good results in 88.2% patients.

Bacterial Infections↗
PubMedDate not supplied

[The evaluation of the possibility of using a perfluorocarbon emulsion for the normothermic perfusion of the isolated heart].

Complex study of isolated heart preparations according to some electromechanical, biochemical, gas transport, and morphofunctional criteria showed that a perfusion medium based on an emulsion of perfluorocarbons ensures an essentially better survival of a heart perfused in a recirculation regimen than with the traditionally used Krebs-Henseleite solution. The analysis shows that the use of perfluorocarbon emulsions as a perfusion medium for prolonged storage of isolated organs is promising.

Animals↗
PubMedDate not supplied

[Identification in vivo of promoter activity in the left site of the att region of bacteriophage lambda DNA].

The promoter-probing vector (pSK plasmid) was explored for cloning of the fragments from lambda cI857 and lambda b2 DNAs containing different regions of the att site. We have constructed all-tet fusions where the fusions are: 1) HindIII/BamHI-491 base pairs (b. p.) fragment of lambda cI857 DNA containing POP' site (plasmid pSK-PP'); 2) AluI-242 b. p. fragment of lambda cI857 DNA containing the left arm of the POP' site (plasmid pSK-P); 3) AluI-242 b. p. fragment of lambda cI857 DNA with opposite orientation (plasmid pSK-P); 4) EcoRI/BamHI-750 b. p. fragment of lambda b2 DNA containing the right arm of the POP' site (plasmid pSK-P'). These fusions permit us to analyse the effect of various pieces of the attachment site on the expression tet gene as the result of reparation of this gene promoter. We find that expression of tet (tetracycline resistant phenotype) takes place in the pSK-PP' and pSK-P but not in the pSK-P' and pSK-P. These facts permit us to conclude that the left arm of the att site contains a rightward promoter functioning in vivo. We postulate that this promoter activity might correspond to the promoter patt, which was described in previous experiments in vitro.

Bacteriophage lambda↗
PubMedDate not supplied

[Plasmid vector for cloning, determination of nucleotide sequence and directed assembly of DNA fragments].

A plasmid vector pNIMB has been constructed (starting) from the pUR222 plasmid as a result of substitution of the polylinker containing restriction sites: PstI, SalGI, AccI, HindII, BamHI EcoRI and by other synthetic linkers with additional sites for HindIII and HgaI. Plasmid pNIMB does not differ from the parent one phenotypically. Compared to pUR222 the vector contains an additional site for cloning HindIII fragments of DNA and allows to clone SalGI/BamHI- and PstI/SalGI-fragments. Cloning of DNA fragments in all seven unique sites of pNiMB gives the possibility for sequencing the fragments avoiding their isolation from the gel. Moreover, this vector may be useful for cloning and directed assembly of chemically synthesised DNA fragments when the endonuclease HgaI sites are used.

Base Sequence↗
PubMedDate not supplied

[Integrase of lambda phage inhibits the activity of promotor Patt under in vivo and in vitro conditions].

In vitro and in vitro transcription of the region of lambda phage DNA containing promoter Patt has been studied. Active transcription was observed in the vicinity of the att site and at the promoter Patt in vivo during the first minutes after infection. This transcription considerably decreases at the 1th minute, and stops completely at the 15th minute after infection. Maximum synthesis of integrase also takes place at the 15th minute after infection. In vitro the partially purified int protein (integrase) completely inhibited transcription from the promoter Patt. Hence, integrase is most probably a repressor of Patt in vivo and in vitro.

Adenosine Triphosphate↗
PubMedDate not supplied

[Isolation and characterization of a phage T7 DNA fragment containing promoter B active in vivo and in vitro].

The fragment of 124 base pairs (Alu-124) has been isolated from the phage T7 DNA and cloned in the plasmid pSK. The sequence of the fragment was determined and position of this fragment on the physical map of phage DNA was found. It has been found that Alu-124 fragment contained an active in vivo and in vitro promoter for E. coli RNA-polymerase. In vitro transcription from this promoter was initiated with GTP. The start of the transcription was localised at about 104 or 105 nucleotide. The data obtained indicate that the Alu-124 fragment of the phage T7 promoter B, may be involved in the control of the transcription of the phage T7 early stage development.

Base Composition↗
PubMedDate not supplied

[Effect of the length of the loop segment of local mRNA secondary structure in the region of lacZ gene translation initiation on its expression].

A number of p50FNL plasmids with a polycistronic operon IX-VIII-IFN-LacZ have been constructed. These plasmids provide the synthesis of polycistronic mRNA translational terminator of gene IFN situated in the coding region of lacZ gene at 41 nucleotide downstreams from its initiation codon. The coding region of IFN gene has been altered by insertions, substitutions, and deletions which provided the formation in the region of local secondary structures differing only by the loop size. The effect of this characteristic of mRNA secondary structure on lacZ translation efficiency has been assessed by measuring the levels of beta-Gal synthesis in E. coli harboring the corresponding plasmids. The level of lacZ expression increased with increase of the loop size. These data confirm that the rate of formation of mRNA secondary structure in the region of translation initiation has a crucial effect on the translation efficacy.

Base Sequence↗