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Biomedical subjects

V L Popov

Publications and source records attributed to V L Popov.

At least 91 records · Page 5Linked to original sources
PubMed1983

[Intrasplenic xenotransplantation of human fetal pancreatic islet cell cultures in rats with experimental diabetes mellitus].

Islet cell cultures obtained from the pancreas of human embryos were transplanted to the spleen pulp of rats with alloxan diabetes mellitus. During 1-2 weeks after transplantation, 6 of the 8 recipients manifested a decrease in glycemia to normal or almost normal. The antidiabetic effect of xenotransplantation of islet cell cultures was well preserved throughout the entire observation period (up to 4 months). Two recipient rats with stable normoglycemia were subjected to splenectomy. One week after operation the animals manifested the recurrent grave diabetic status. Histological study of the removed spleen has shown the red pulp to contain the accumulations of implanted islet cells.

Animals↗
PubMed1983

[Isolation of the 1st strains of Legionella pneumophila in the USSR].

For the first time L. pneumophila strains were isolated from pneumonia patients in the USSR. To isolate these strains, the material obtained from the patients was inoculated into charcoal-yeast agar with antibiotics or into guinea pigs with the subsequent inoculation of chick embryos. Both isolated strains were classified with serogroup 1 of L. pneumophila on the basis of their cultural, morphological, biochemical and serological properties.

Acute Disease↗
PubMed1982

[Ultrastructural localization of type-specific antigen of legionella pneumophila].

Cell suspensions of Legionella pneumophila, a virulent Philadelphia I strain, were incubated with rabbit antiserum to type-specific heat-sensitive antigen III having toxic properties with the use of the indirect immunoferritin technique. Antigen III was localized in the outer fibrillar microcapsule-like layer 12-20 mm thick. In the direct immunoperoxidase test antigen III had globular localization on the cell wall surface. The layer described is unlikely to be a true microcapsule, since it does not contain acid mucopolysaccharides and is readily removed from the cell. It is more likely that it forms as a result of antigen III secretion (and, possibly, of other antigens) being more similar to a capsule-like or mucilagenous layer.

Antigens, Bacterial↗
PubMed1981

[Citrobacter freundii interaction with epithelial cells and macrophages in vitro].

Electron-microscopic study has revealed the capacity of enteropathogenic C. freundii strain to adhere to the glycocalyx of epithelial HeLa cells, to proliferate on their surface and to induce the toxic damage of their organelles. C. freundii, possessing a fibrillar microcapsule, have been shown to be capable of resisting the action of the lysosome enzymes of guinea-pig macrophages and disorganizing macrophage cultures. The latter fact should be taken into consideration in working with C. freundii strains isolated in the process of diagnostic examination.

Animals↗
PubMed1980

[Ultrastructure of the initial stages of interaction between halprowiae (Chlamydiae) and host cells].

The initial stages of the interaction of halprowiae (strain CP-1), isolated in Reiter's syndrome, with a monolayer culture of cells L-929 were studied. The electron-microscopic examination of the cells every 2 hours during the first 24 hours after the inoculation allowed to follow the processes of adsorption, endocytosis of elementary bodies and their transformation into reticulate bodies by the "decondensation" of nucleoid, which indicated the beginning of the vegetative (reproductive) stage of the developmental cycle. During all the periods of observation halprowiae were enclosed into the membranes of phagocytic vacuoles formed by host cells. Besides, in other vacuoles (probably, phagolysosomes) halprowiae at various stages of destruction could be observed. 8--10 hours after inoculation the phagosomes containing reticulate bodies began to merge, thus forming an inoculation the phagosomes containing reticulate bodies began to merge, thus forming an intracytoplasmic inclusion. In this inclusion a new generation of the agent was formed by binary-like fission. At the beginning of the vegetative stage halprowiae seem to be highly sensitive to the action of exo- and endogenic factors which may cause their L-transformation. Depending on the reaction of the host cell at the initial stages of interaction with halprowiae, 3 ways of such interaction are seemingly possible: developmental cycle, destruction in phagolysosomes. L-transformation.

Adsorption↗
PubMed1979

[Use of a cryoultramicrotomy method for the purpose of studying chlamydial ultrastructure].

The method of cryoultramicrotomy was adapted for the study of the ultrastructure of HeLa and McCoy cells in monolayer cultures infected with Chlamydia, obligatory intracellular procaryotic parasites, the causative agents of ornithosis (strain Loth) and paratrachoma (strain LB 1). The cryosections were obtained by the fixation of the monolayer with 2.5% glutaraldehyde, by the gradual infiltration of precipitated cells with sucrose (0.6--1.2--1.8--2.3 M) prior to freezing in liquid nitrogen, and by the treatment of sections with 1% aqueous methyl cellulose solution before drying. This method ensured good preservation of both Chlamydia, in intracytoplasmic inclusions and host cells, as well as regular reproducibility of the results. Ultrathin sections showed a considerable polymorphism in the vegetative forms of Chlamydia, which was probably due to the structure of their cell walls. Chlamydia, were found to form small vesicle-like structures in the cavities of inclusions. The cell walls and granules inside the elementary bodies of the causative agent of ornithosis were stained with the use of phosphotungstic acid--HCl, pH 0.5.

Chlamydia↗
PubMed1979

[Action of penicillin on the causative agent of paratrachoma in the dynamics of an in vitro infection].

Monolayer cultures of L-cells (mouse fibroblasts) were inoculated with the causative agent of paratrachoma (strain LB-I). Simultaneously penicillin in doses of 0.01, 0.1, 1, 10, 25, 50, 100, 150 and 200 microgram/ml was added and its effect on the causative agent in the infection dynamics (18, 24, 48 and 72 hours after the inoculation) was studied with the light and electron microscopes. Gradual changes in the ultrastructure of the vegetative forms were observed by the 24th hour with the use of penicillin in a dose of 0.01 microgram/ml: the size of the vegetative forms increased, the cell wall membranes separated and periplasmic space significantly enlarged, the protoplast fragments disjoined into it, large forms vacuolized and were fragment with membranes, sometimes multilayer ones. When the culture was exposed to large doses of penicillin, the rate of the changes in the structure was higher and they were simultaneously of several types. Various types of the changes and possible modes of their formation were analyzed. Morphologically they are similar to the processes observed in L-transformation of bacteria. However, these structures were not infectious.

Animals↗
PubMed1977

[Unusual small forms in the growth cycle of halprowia (chlamydia) and their possible relation to manifestations of L-transformation].

The authors carried out a comparative electron-microscopic study of the ultrastructure and the developmental cycle of 15 Halprowiae (chlamydiae) strains isolated in different pathology from man and animals. Halprowiae were cultivated in the yolk sac epithelium of the developing chick embryos and in the L-cell monolayer cultures without any special action of the antibiotics and medicines. Formation of minute round structures ("minute forms"), 50--120 nm in diameter, separating from the protoplast into the periplasmic space and surrounded with cytoplasmic membrane by the vegetative forms of a number of strains (MP, AP-23, 25-SM, LB-1, MyB), is described. Along with minute forms, Halprowiae formed polymorphous giant bodies with long protrusions into the inclusion cavity; there was also a separation of vesicles of the cell wall membrane. This apparently indicated a structural derangement of the cell wall in these vegetative forms of Halprowiae. On the basis of similarity of the mentioned structures detected in Halprowiae reproduction to the known morphological characteristics of the L-form bacteria a possibility of L-transformation in Halprowiae during the normal developmental cycle as a peculiar compensatory adaptation to the action of host cell is supposed.

Chlamydia↗
PubMed1976

[Morphology of Halprowia (Chlamydia) isolated in Reiter's syndrome].

Morphology and ultrastructure of Halprowia arthritidis, strain SR-1 (HSR), isolated from the synovial fluid of a patient with Reiter's syndrome, was studied in the membranes of the yolk sacs of the developing chick embryos and the L-cell culture. In acridine orange staining for light and fluorescent microscopy there was revealed intracellular cytoplasmic inclusions containing HSR structures at various stages of its reproduction characteristic of halprowia (chlamydia). The direct immunofluorescent method demonstrated the presence of a characteristic HSR antigen not only in the developed inclusions, but also at the early stages of infection, when the morphological HSR structures could not be found by light microscopy. The ultrastructure of the HSR inclusions and forms in the cycle of development (of the initial and elementary bodies) of the SR-1 strain was typical of other halprowia. A peculiar structure of a complex of cell wall and cytoplasmic membrane of the elementary body was described. Taking into consideration the biological characteristics of HSR revealed earlier it can be considered to be a typical representative of Halprowiales s. Chlamydiales. The data obtained on other halprowia, pointing out the fact that criteria of compactness and diffuseness of inclusions, the presence of absence of glycogen in the inclusions could not serve as taxonomic signs in classification of halrpowia, were confirmed on a model of the SR-1 studied.

Animals↗
PubMed1976

Electron microscopy of surface structures of Rickettsia prowazeki stained with ruthenium red.

In studying surface structures of Rickettsia prowazeki (E and Breinl strains) by ruthenium red staining, a microcapsular layer 125-165 A thick, composed of subunits 85--100 A in diameter with a periodicity of 100--120 A as well as the inner layer of the cell wall 40--60 A thick were clearly revealed. In tangential sections of cells, subunits of the microcapsular layer were found in parallel striation arrays. These structures presumably contain acid mucopolysaccharides detectable by ruthenium red staining. Besides, hitherto unreported intracytoplasmic membrane structures were detected in ruthenium red-stained rickettsiae.

Cell Membrane↗
PubMed1976

[Electron microscopic determination of the localization of the group-specific antigen of Halprowise (Chlamydiae) by the direct immunoperoxidase method].

The direct immunoperoxidase technique was applied to the study of the localization of a group-specific antigen of Halprowiae (Chlamydiae) in the causative agents of meningopneumonia (strain MP) and of paratrachoma (strain LB-I) at the individual stages of their developmental cycle in the L-cell (16, 24 and 48 hours after infection of the culture). The product of reaction to peroxidase pointing to the localization of the group-specific antigen was localized not only on the surface, but in the whole thickness of the cell wall of the initial bodies in the form of an even electron dense layer, 200--280 A in thickness. A weak positive reaction was also noted on the outer layer of the sytoplasmic membrane. The periplasmic space remained free of the reaction product. Localization of the reaction product in the intermediate and elementary bodies remained unchanged. At the initial stages of the developmental cycle (16 hours after the infection) the reaction) the reaction product was revealed not in the whole cell wall, butin some of its areas only. There were found no qualitative differences in the localization of the group-specific antigen in the Malprowiae strains under study.

3,3'-Diaminobenzidine↗
PubMed1976

[Indication of halprowia (chlamydia) antigens by the direct immunoperoxidase method].

The authors modified and approbated the direct immunoperoxidase method for the indication in the infected L cells of the halprowia (chlamydia) antigens--etiological agents of trachoma, ocular and urogenital forms of paratrachoma, arthritis, meningopneumonia and enzootic abortion of sheep. Different types of localization of the group-specific halprowia antigen were revealed in the cytoplasm of the affected cells by light microscopy; electron microscopy demonstrated localization of this antigen in the membrane of the cell wall of the elementary and initial bodies. Specificity of the test-system used, no lesser sensitivity than the sensitivity of direct immunofluorescent method of indication of the same microbies, with a possibility of detection of stably stained antigens by widely accessible light microscopy underly practical usefulness of direct immunoperoxidase method of the diagnosis of halprowiosis (chlamydiosis) of man and animals.

Antigens, Bacterial↗
PubMed1975

[Cultivation of F. tularensis in developing chick embryos].

In cultivation of the causative agent of tularemia in the organism of chick embryos (8-10 days of incubation) it was found that the virulent strains multiplied intensively in the yolk sacs causing the death of the embryos on the 3rd-4th day after the infection; as to the virulent strains-they were only preserved in the embryos. The period of death of the embryos and the accumulation of bacteria depended on the strain virulence. No differences in the anatomical structure of the cells belonging to the virulent and avirulent strains could be found.

Animals↗
PubMed1975

[Current data on the polymorphism of Rickettsia prowazekii and burneti in cultured cells].

In cultivation of Rickettsia prowazeki (strains Breinl and E) in the cell cultures of guinea pig kidneys (GPK) and chick embryo fibroblasts (CEF) ultrastructure of rickettsia of unusual shape (filamentous, irregularpleomorphic and spheroplast-like) were revealed along with rickettsia of the usual shape and size. The polymorphism was less pronounced in the GPK and the CEF cells of Rickettsia burneti (strain M-44). It is supposed that rickettsial polymorphism was not associated with their developmental cycle and served as a morphological expression of the changes in the microorganism under the effect of unfavourable ecological conditions. The appearance of filamentous forms could be associated with disturbed cell division process; changed rigidity of the cell wall could serve as the cause of appearance of pleomorphic rickettsia. In difference from polymorphism, the cycle of rickettsial development is considered to be (in the basis of modern electron microscopic data) as a biological replacement of the vegetative (rod-like, bacillary) forms by those more stable in the external environment, resting (coccoid).

Animals↗