[Effect of alkylresorcinols on thermal denaturation and refolding of bacterial luciferase and synthesis of heat shock proteins revealed in the luminescent molecular and cellular test systems].

Molecular and cellular luminescent biotests were used to reveal the effects of five alkylresorcinol homologues (C7-, C9-, C11-, C12-, and C18-AR) on the thermally induced denaturation and refolding ofbac- terial luciferases, as well as on the synthesis of heat shock proteins. The ARs activities were found to depend on their fine structure and concentration. Direct heat-protective effect of short-chain C7- and C9-AR on the chromatographically pure Photobactrium leiognathii luciferase/oxidoreductase was shown within broad range of concentration (10(-6)-10(-3) M). The long-chain ARs homologues exhibited a similar heat-protective effect at micromolar concentrations only, while their millimolarconcentrations have increased the sensitivity of the model proteins to thermal treatment. The recombinant strain Escherichia coli K12 MG1655 bearing constitutively expressed Vibrio fischieri luxAB genes was used to investigate theARs effect on the intracellular chaperone-independent refolding of bacterial luciferase. The functional activity of heat-inactivated enzyme was restored by micromolar concentrations of short-chain ARs, while long-chain homologues inhibited re- folding in the wide concentration range. The recombinant luminescent E. coli strain bearing the inducible ib- pA'::luxCDABE genetic construction was used to determine the effect of ARs on the synthesis of heat shock proteins (HSP). The preincubation mode of bacterial cells with long-chain alkylresorcinols led to dose-de- pendent stimulation of HSP synthesis (2.7 to 4 times) that confirmed some ARs function as "alarmones". Subsequent thermal treatment resulted in a 5-15-fold decrease of the following HSP induction compared to the control, while the number of viable cells opposite increased 1.5-4-fold. Thus, pretreatment of the bacte- rial cells with long-chain ARs resulted in their preadaptation to subsequent thermally induced stress. Short- chainARs caused less pronounced HSP suppression, although still was accompanied by increased heat resis- tance of the AR-pretreated bacterial cells.

[IR spectroscopic research on the impact of chemical analogues of autoregulatory d1 factors of microorganisms on structural changes in DNA].

Using IR spectroscopy, we investigated the impact of chemical analogues of autoregulatory d1 factors of microorganisms (methylresorcinol, hexylresorcinol, and tyrosol) on the conformational changes in DNA in films upon altering (decreasing) the relative humidity. We analyzed the appearance/disappearance of characteristic absorption bands of A and B DNA forms and determined D1080/D1224, the ratio between the band intensities of symmetrical and asymmetrical oscillations in their phosphate groups. The data obtained suggest the slowing down of the B-->A structural transition in DNA in the presence of methylresorcinol and its speeding up in the presence of tyrosol. We discuss the mechanisms of this phenomenon in relation to the chemical composition of d1 factors and their biological function.

[Long-term preservation of DNA in aqueous solutions in the presence of the chemical analogues of microbial autoregulators].

The fact of long-term preservation of the physicochemical properties of DNA molecules in aqueous solutions in complexes with methylresorcinol, hexylresorcinol, and tyrosol, the chemical analogues of microbial autoregulators (d1 factors) from the group of alkylhydroxybenzenes (AOB), was established. Compared to the control variants of storage of aqueous DNA solutions, the AOB influence consisted in the sum of correlating effects: the prevention of DNA degradation (according to spectrophotometric parameters) and the preservation of its viscous characteristics and electrophoretic mobility. The initial DNA properties were preserved to the greatest degree in the presence of hexylresorcinol, the compound with the longest alkyl radical. Possible mechanisms of the protective action of alkylhydroxybenzenes in relation to DNA are discussed, namely, the prevention of its hydrolysis due to isolation from the aqueous environment and maintaining DNA stability in the dormant forms of microorganisms.

[Influence of chemical analogues of microbial autoregulators on the sensitivity of DNA to UV radiation].

We established that chemical analogues of alkylhydroxybenzenes (AHB), belonging to alkylresorcinols and functioning as microbial autoregulatory d1 factors, enhance the UV resistance of various DNA molecules of different origin and conformation. These include the linear DNA of the lambda phage, bovine spleen DNA, and the DNA of the pUC19 plasmid that is composed of a number of annular (supercoiled and relaxed) and linearized molecules. Irradiating DNA with UV light (lambda = 254 nm) in the presence of methylresorcinol (MR) or hexylresorcinol (HR) results in comparatively insignificant DNA destruction as evidenced by our data on the electrophoretic mobility pattern in agarose gel. Using the linear Hind III restricts of the lambda phage DNA, we revealed that the protective effect of AHB varies depending on their chemical structure (it is more manifest with HR than MR) and concentration. Importantly, the effect of HR on bovine spleen DNA was based on its protective activity and manifested itself after a long incubation period. Studies using the pUC19 plasmid demonstrated that AHB, apart from increasing the resistance of linearized DNA molecules to UV irradiation, prevented both the supercoiled annular-supercoiled relaxed and the supercoiled relaxed-linearized transitions. The possible mechanisms of the UV-protective effect of AHB on DNA and their contributions to the resistance of dormant microbial forms to environmental factors are discussed.

[Mechanisms of interaction between DNA and chemical analogues of microbial anabiosis autoinducers].

The alkylhydroxybenzene (AHB) autoregulatory factors d1 (fd1) of microorganisms have been found to directly interact with highly polymeric DNA. This circumstance results in changes, related to alterations in the topology of this macromolecule, in DNA physicochemical properties. The physicochemical properties of DNA in the presence of chemical analogues of microbial AHBs (methylresorcinol; hexylresorcinol; and 2-(4-hydroxyphenyl)ethane-1-ol, also known as tyrosol) were investigated using adsorption spectrophotometry, fluorometry, heat denaturation, viscosimetry, and electrophoresis in agarose gel. A number of concordant effects pointing to DNA-AHB interactions were revealed that manifesed themselves in the hypochromic properties of the resulting complexes, an increase in their melting temperature and viscosity, a decrease in their electrophoretic mobility, and a change in the fluorescent properties of AHBs upon complexation with DNA. Such alterations were particularly significant in the presence of hexylresorcinol, which possessed the maximum alkyl radical length among the fd1 analogues tested. Using atomic force microscopy, we visualized the micelle-like DNA nanostructures forming in the presence of AHBs. The results obtained provided the basis for developing a hypothetical model of the interaction between the biopolymer macromolecule and low-molecular-weight AHBs that takes into account the differences in the hydrophobicity of individual AHB homologues functioning as ligands. In terms of our model, we discuss AHB involvement in the stabilization of DNA and alteration of its topology, i.e., in the process related to intragenomic rearrangements, which account for the intrapopulational variability of bacteria, including dissociation processes.

[The evaluation of the body response of experimental animals to exposure to the magnetic component of electromagnetic radiation for setting a hygiene standard]. / Otsenka otvetnoi reaktsii organizma podopytnykh zhivotnykh na vozdeistvie magnitnoi sostavliaiushchei élektromagnitnogo izlucheniia dlia gigienicheskogo normirovaniia.

Acute and subacute experiments were conducted to evaluate threshold response of white rats to variable magnetic intensity of magnetic section of electromagnetic irradiation with fixed frequency (3 MHz).

[Methodologic aspects of combined physiotherapeutic effect]. / Metodologicheskie aspekty problemy kombinirovannogo fizioterapevticheskogo vozdeistviia.

The paper describes a conceptually logic and mathematical model of the body's responses to the combined exposure to several physiotherapeutical factors. The model has been developed by transforming the basic differential equation of Volterra's survival theory and realizing as a computer program. The model enables one to find the optimal combinations of the parameters of the influencing factors which produce the maximum therapeutical effect without exhausting the compensatory abilities of the body's physiological systems.

[Changes in the myocardium of fetuses and newborn infants as a result of hypoxia]. / Izmeneniia miokarda u plodov i novorozhdennykh detei v usloviiakh gipoksii.

Myocardium has been investigated in 68 human fetuses and newborns suffered from intrauterine acute and prolonged hypoxia, occurred as a result of various maternal, fetal and placental diseases. Under acute hypoxia only reactive changes of the contractile myocardium appear. They are demonstrated as degeneration of muscle fibers and appearance of scattered foci of necrosis in cardiomyocytes. Under a prolonged hypoxia, besides analogous reactive changes, compensatory hypertrophy of some part of cardiomyocytes is noted; this is manifestation of a compensatory-adaptive reaction of the myocardium.