Biomedical subjects

O V Egorova

Publications and source records attributed to O V Egorova.

8 recordsLinked to original sources

PubMed2005

Localization of 17beta-hydroxysteroid dehydrogenase in Mycobacterium sp. VKM Ac-1815D mutant strain.

The localization of mycobacterial 17beta-hydroxysteroid dehydrogenase (17beta-OH SDH) was studied using cell fractionation and cytochemical investigation. Mycobacterium sp. Et1 mutant strain derived from Mycobacterium sp. VKM Ac-1815D and characterized by increased 17beta-OH SDH activity was used as a model organism. Subcellular distribution study showed both soluble and membrane-bound forms of mycobacterial 17beta-hydroxysteroid dehydrogenase. The cytochemical method based on a copper ferrocyanide procedure followed by electron microscopic visualization was applied in order to investigate the intracellular localization of bacterial 17beta-OH SDH in more detail. The enzyme was found to be located in the peripheral cytoplasmic zone adjoining the cytoplasmic membrane (CM). 17beta-OH SDH was loosely membrane bound and easily released into the environment under the cell integrity failure.

17-Hydroxysteroid Dehydrogenases↗

PubMed2004

Extracellular 3beta-hydroxysteroid oxidase of Mycobacterium vaccae VKM Ac-1815D.

Extracellular 3beta-hydroxysteroid oxidase (SO) has been isolated from cell-free cultivation broth at the growth of Mycobacterium vaccae VKM Ac-1815D on glycerol-mineral medium in the presence of sitosterol. The enzyme is responsible for the transformation of 3beta-hydroxy-5-ene- to 3-keto-4-ene-moiety of steroids including dehydrogenation of 3beta-hydroxy function followed by delta5-->delta4 isomerization. 6-Hydroxy-4-sitosten-3-one and 6-hydroxy-4-androsten-3,17-dione were revealed among the metabolites at the incubation of the enzyme preparations with sitosterol and dehydroepiandrosterone (DHEA), respectively. The enzyme was strongly NADH or NADPH dependent. SO has been purified over 300-fold using cultivation broth concentration on hollow fibers followed by fractionation by ammonium sulphate, column chromatography on DEAE-Toyopearl, hydroxyapatite Bio-Gel HTP and double gel-filtration on Bio-Gel A 0.5 M. SDS-electrophoresis gave a molecular mass estimate of 62 +/- 4 kDa. The purified SO obeyed Michaelis-Menten kinetics, double reciprocal plots kinetics revealed Km value towards DHEA 5 x 10(-4) M. Along with SO activity, 17-hydroxysteroid dehydrogenase (17-OH SDH) and 3-ketosteroid-1(2)-dehydrogenase (1(2)-SDH) activities were detected in cell-free cultivation broth. The extracellular steroid transforming activities of C-17-ketosteroid producing mycobacteria were hitherto unreported.

3-Hydroxysteroid Dehydrogenases↗

PubMed2003

Experimental analysis of the processes of systems genesis: expression of the c-fos gene in the chick brain during treatments inducing the development of the species-specific results-of-action acceptor.

The aim of the present work was to identify which parts of the chick brain are activated during treatments inducing the development of the preference to follow a species-specific object (a stuffed chick). Expression of the gene for the transcription factor c-fos was used as the molecular marker for neuron activation. Day-old chicks lacking visual experience were placed for 90 min in a freely rotating squirrel wheel or were subjected to stimulation with a loud noise for 180 min. The animals' preference was tested 24 h after stimulation ended. Both types of stimulation induced the formation of a marked preference to follow the "natural" object in the chicks. c-fos expression was analyzed in sections from the brains of chicks stimulated for 45 min. Increases in the quantity of c-fos mRNA were seen after each type of stimulation in the medial part of the caudal neostriatum. In addition, stimulation in the squirrel wheel was accompanied by high levels of c-fos expression in the paraolfactory lobes, while sound stimulation gave high levels of c-fos expression in the ventral and caudal parts of the archistriatum. These structures of the chick brain are of great interest for studies of the cellular and molecular mechanisms of the formation of the species-specific results-of-action acceptor in the mother-following functional system.

Acoustic Stimulation↗

PubMed2002

17-Hydroxysteroid dehydrogenases of Mycobacterium sp. VKM Ac-1815D mutant strain.

Whole cells and crude extract of Mycobacterium sp. VKM Ac-1815D mutant strain Et1 were shown to carry out 17beta-reduction, 17beta-dehydrogenation and 1(2)-reduction of 3-keto-C(19)-steroids. Two 17-hydroxy steroid dehydrogenases (17-OH SDH) were partially purified from the strain by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-sephacel and gel-filtration on Bio-Gel A. The enzymes differed in chromatographic properties and specific activities. One enzyme--17-OH SDH (2) (tetramer, M(r) approximately 210,000) was found to be responsible for bi-directional reduction-oxidation of steroids at C 17, whereas the other one--17-OH SDH (1) (monomer, M(r) approximately 68,000) specifically catalysed 17beta-dehydrogenation of 17-hydroxysteroids (testosterone and 1(2)-dehydro testosterone). The 17beta-reduction of 1-ene-17-ketosteroids was accompanied by 1(2)-reduction. A role of 1-ene-reductase as a steroid-binding protein associated with 17-OH SDH (2) in Mycobacterium sp. is discussed.

17-Hydroxysteroid Dehydrogenases↗

PubMed1968

[Solaritis].

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Celiac Plexus↗

PubMedDate not supplied

[Experimental analysis of systemogenesis process: c-fos gene expression in chicken brain during stimulation of development of a species-specific acceptor of action response].

The aim of this study was to localize the areas of the chick brain involved in the development of filial predisposition to follow conspecifics. Expression of the immediate early gene c-fos mRNA was used to map such structures. One-day-old chicks were stimulated (primed) by placing for 90 min into a running wheel in darkness or by exposure to a loud nonspecific sound for 180 min. Brains of a part of these chicks taken 45 min after the beginning of priming were used for c-fos expression study. The remaining chicks were tested 24 hours after priming by simultaneous presentation of a "natural" object (stuffed fowl) and an "artifical" object (rotating red cube). Primed chicks demonstrated significant preference for the natural object as compared to untreated control chicks. In the forebrain of chicks primed both in the running wheel and by acoustic stimulation a significant c-fos expression was found in the medial part of the caudal neostriatum. Priming in the running wheel additionally induced c-fos expression in the lobus parolfactorius, while priming by acoustic stimulation produced high c-fos expression in the archistriatum. Both these areas are known to be involved in filial imprinting. The results suggest that these structures can be also involved in the development of filial predisposition in chicks.

Animals↗

PubMedDate not supplied

[Enzymes involved in modification of the steroid nucleus of industrial mycobacterial strains: isolation, functions, and properties].

The key enzymes involved in modification of the steroid nucleus of sterol-transforming mycobacteria--3beta-hydroxysteroid oxidase (3-OH-SO, EC 1.13.1.2) and 17beta-hydroxysteroid dehydrogenase (17-OH-SDH, EC 1.1.1)--were isolated and characterized. It is shown that 3-OH-SO is a multifunctional enzyme catalyzing oxidation of the 3beta-OH group, delta5 --> delta4 isomerization, and 6-hydroxylation. Two forms of intracellular 17-OH-SDH that catalyze redox reactions at C17 were found, and their properties were determined. The presence of an extracellular 17-OH-SDH in Mycobacterium spp. (VKM Ac-1815 D and Et1) was demonstrated for the first time.

3-Hydroxysteroid Dehydrogenases↗

PubMedDate not supplied

[Diagnosis of cardiac rhythm disorders in pilots using 24-hour ECG monitoring].

As a result of comprehensive examinations of 57 pilots, aged 31 to 50 years, which included multi-step bicycle ergometry, specific tests simulating flight effects (e.g., positive pressure breathing, moderate hypoxia, radial acceleration) and 24-hour Holter monitoring, various cardiac arrhythmias were identified in 37 subjects (64.9%). They included supraventricular ectopic beats and ventricular ectopic beats of different grades. It was demonstrated that Holter monitoring was very reliable in comparison with conventional methods such as ECG at rest, bicycle ergometry or specific tests. In 5 cases, transient cardiac arrhythmias were associated with ischemic heart disease manifestations. The method of Holter monitoring is recommended to be used in medical expertise of the aircraft personnel.

Adult↗