Biomedical subjects
Publications and source records attributed to V G Kuznetsov.
Compared and contrasted were models of radiation shielding of habitable compartments of the basal Mir module that had been used to calculate crew absorbed doses from space radiation. Developed was a model of the ISS Service module radiation shielding. It was stated that there is a good agreement between experimental shielding function and the one calculated from this model.
A four-tube method with diagnostic nutrient media is proposed for differentiating between pathogenic and apathogenic Yersinia. Yersinia cultures are detected by inoculating typical or suspected colonies from solid media to media with lactose, glucose, urea, and indicators. Subsequent culturing in three other media (with sucrose and sorbitol, with esculin, rhamnose, and salicin, and with pyrasinamide) and the use of appropriate indicators help detect potentially pathogenous pseudotuberculous and enteric Yersinia of 1B, 2, 3, and 5 biovars from apathogenic species and variants. The method is simple, rapid, economic, reliable, and is recommended for clinical laboratory diagnosis.
A modified crystal violet method and common agarose medium are proposed for culturing Yersinia before staining. The dish variant is recommended for large quantities and the tube variant for individual strains. Up to 25-30 colonies (plaques) are inoculated into a petri dish and a "dash" inoculation is made into oblique agar in tubes. The cultures are incubated for 24 h at 37 degrees C. After 3-min staining (100 micrograms/ml) of the resultant cultures three phenomena are observed due to the presence of a virulence plasmid with molecular weight of 45-48 megadalton in the strain: violet staining (CV+ test), adhesion to substrate (adhesion+), and adhesion of Yersinia cells to each other (autoadhesion+). Strains with these phenotypical signs are virulent. The proposed method is simple, informative, and reliably detects virulent strains of Yersinia among apathogenic and pathogenic species (variants) isolated from clinical or epidemiologically significant materials.
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From 43 (35.8%) out of 120 samples of pasteurized milk used by volunteers 182 cultures of five Yersinia species--Y. enterocolitica, biovar 1 (70.3%), Y. intermedia (18.1%), Y. frederiksenii (7.7%), Y. kristensenii (3.3%) and Y. aldovae (0.5%)--were isolated in the course of bacteriological studies carried out in 1987-1990. The isolated Yersinia cultures belonged to nonpathogenic pyraminidaze-positive serovars. Yersinia pathogenic bio/serovars (4/O3, 2/O9, 1B/O8) were not detected. No deviations from the normal state were registered in the volunteers drinking pasteurized milk, and Yersinia could be isolated from their feces only during the first 3 days following milk consumption. In 390 patients examined for the presence of Yersinia infections the isolation rate of Yersinia of biovar 1 (99.6% of the cultures) varied between 4.4% and 21.3% and correlated with the increase of the isolation rate from milk (13.6% to 53.9%). The results of the study suggest that unboiled pasteurized milk contributes to the spread of Yersinia carriership among the population.
A modified nutrient medium, made of reagents and standard media manufactured in this country, tried in practice, is suggested for Yersinia pyrazinamidase test. Tisamid (Finland), a pyrazinamide antituberculosis agent was used as substrate. A positive test is characteristic of nonpathogenic and a negative one for pathogenic Yersinia. The test and the medium may be effectively used in laboratory diagnostic studies for identification of Yersinia.
For the first time Y. intermedia strains containing plasmids with a molecular weight of 82 MD have been detected in natural populations of urease-positive Yersinia. Such populations have been isolated from two species of birds and from the soil in the area where they have been killed (the Maritime Territory), as well as from washings from the surface of onions in a vegetable store (Chita Province). The strains, administered orally to white mice, proved to be nonpathogenic. Plasmids with a molecular weight of 82 MD are supposed to occur in natural populations of other Yersinia species.
A comparative analysis of changes in ultrastructure of neuro-muscular synapses of three types has been studied in the rat diaphragmal muscle at an acute poisoning with chlorophos. A high stability to the damaging action of chlorophos in white muscle fibers has been revealed in comparison with other types. The most essential changes of the ultrastructure have taken place in slow intermediate fibers. These differences are evidently connected with certain peculiarities in morphofunctional organization of calcium-sequestring ++ components of three types of muscle fibers (sarcotubular system, mitochondria) and presence of parvalbulin.
To study the ecology of Yersinia, culture media, the pool method and the algorithm for their isolation and identification are proposed. The correct selection of typical Yersinia colonies grown in special media is the major step. This permits the study of culture pools (their amount reaching 12 and more from each sample) and makes it expedient to use the economical dish method for obtaining pure cultures and identifying Yersinia by the minimal set of key signs. The use of these methods makes it possible to study a great number of cultures and to obtain valuable information on local Yersinia populations with the least expenditures.
For the first time the habitats of saprophytic and parasitic Yersinia populations have been analyzed on the basis of data obtained in the study of the sources of their isolation. Soil with underground and surface water, forming an integral dynamic habitat system, is considered to be the fundamental ecological niche for all Yersinia species. Within this niche, the saprophytic populations occupy individual natural and anthropogenic ecological niches, while the parasitic populations occupy individual selective ecological niches (animal and human bodies). The subdivision of niches occupied by infective agents into biological (universal), ecological and epidemiological is substantiated from the ecological standpoint.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The effect of acidin-pepsin solution at a concentration of 1 : 100 on newly isolated Yersinia cultures has been tested in three series of experiments. Acidin-pepsin has been found to exert a bactericidal effect on Yersinia and to induce the appearance of involutionary forms and large rod-shaped Yersinia cells with a better capacity for survival. The surviving Yersinia cells do not pass their resistance to acidin-pepsin on to their progeny and show low invasiveness and pathogenicity in white mice.
Ultrastructural changes of rat diaphragm muscle fibers were studied after administration of chlorophos, i. e. organophosphorus inhibitor. Observations were made 10-180 seconds after treatment (concentrations--18 and 24 mM). The swelling of mitochondria and the increase in the length of sarcomeres were observed simultaneously. These changes were phasic. The swelling of mitochondria is probably due to the increase in energetical activity of muscle fibres.
Ultrastructural changes of the rat diaphragm muscle fibers and electron histochemical distribution of calcium ions were studied following chlorophos administration in 5, 15 and 45 minutes (dose - 300 mg/kg, intraperitoneally). The local swelling of mitochondrial matrix and the appearance of contractures were found first in postsynaptical region. Then the postsynaptical alterations increased; the swelling and fragmentation of sarcoplasmic reticulum were observed in addition to desorganization of mitochondrial ultrastructure. Granules of the histochemical product were revealed in mitochondria, in the sarcoplasmic reticulum and in filaments. Changes in distribution of calcium ions in the rat diaphragm muscle fibres after chlorophos administration and the role of Ca++ the in the mechanism of muscle alteration discussed.