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Biomedical subjects

V G Seliverstova

Publications and source records attributed to V G Seliverstova.

At least 19 recordsLinked to original sources
PubMed2005

Myocardial tissue damage in rabbits injected with group A streptococci, types M1 and M22. Role of bacterial immunoglobulin G-binding surface proteins.

Acute rheumatic fever (ARF) and acute poststreptococcal glomerulonephritis (APSGN), two important sequelae of streptococcal throat or skin infections, according to current concepts may be elicited by autoimmune mechanisms due to molecular mimicry between group A streptococci (GAS) and human tissue. In the case of APSGN, however, our experimental data have indicated that GAS immunoglobulin-binding surface proteins (IgG BPs) might be of pathogenic significance by triggering anti-IgG production and immune complex formation leading to renal damage. Thus, rabbits injected with IgG-binding, as opposed to non-binding, GAS strains were found to develop renal deposition of IgG and complement factor C3 and inflammatory and degenerative glomerular changes resembling the picture seen in APSGN. In the present study, cardiac tissue material from rabbits injected with GAS was investigated. After 8 or more weeks of intravenous (i.v.) injections, minimal changes were seen in those animals receiving an IgG non-binding GAS strain, type T27, whereas those animals receiving either of two IgG-binding GAS strains, types M1 or M22, developed strong inflammatory and degenerative myocardial changes accompanied by deposition of IgG and C3. Furthermore, on injecting rabbits with defined mutants of a type M22 strain, the development of myocardial tissue damage proved to be dependent on the presence of streptococcal IgG-binding activity. Our results demonstrate that myocardial tissue changes may be induced in the rabbit by i.v. injection of whole heat-killed GAS of at least two M serotypes. Conceivably, induction of immune complexes by bacterial IgG BPs may lead to myocardial deposition of IgG, in turn triggering a series of events, involving the complement system and proinflammatory cytokines, with resulting tissue damage. Though many virulence factors may be involved in the development of ARF and APSGN, and a given GAS strain will never cause both, our results may suggest a new pathogenetic mechanism common to these two major non-suppurative complications.

Animals↗
PubMed2005

[The immune system, atherosclerosis and persisting infection].

The paper demonstrates that lymph nodes situated in the vicinity of magistral blood vessels are the source of immune and inflammatory response to LDL as the main pathogenetic factor in atherosclerosis. The activation of T-cell-mediated immunity takes place in them at the very early stages of the disease, resulting in forming of CD4+T-lymphocytes, activated mononuclear cells and immunostabilizing B-lymphocytes. The cell changes in lymph nodes correlate with the severity of atherosclerotic lesions in the vessel intima and closely reflect the peculiarities of immune inflammation development in fatty streaks and atherosclerotic plaques in human atherogenesis. A paradoxical reaction was observed in cases with Chlamydia pneumoniae found in the wall of aorta and paraaortal lymph nodes. No evident immune response on the part of immunocompetent cells took place, but, on the contrary, the function of mononuclear cells, including T-lymphocytes, was suppressed. This phenomenon may be explained by the fact that intracellular localization of Chlamydia pneumoniae hides it from immune system control or by the possible microorganism capability of direct immunosuppressive influence on lymphoid cells both in the blood vessel wall and in regional lymph nodes.

Aorta↗
PubMed2003

[Development of adrenal chromaffin tissue].

The purpose of the present investigation was to study the morphological peculiarities of chromaffinoblasts and to determine their interrelations with the surrounding cellular elements of the fetal cortex at the early stages (embryonic weeks 4-7) of their migration into the developing adrenal gland of a pig. At week 5 neuro-cellular cords, consisting of so-called "naked" axons, neuroblasts, lemmoblasts, undifferentiated cells, chromaffinoblast clusters and chromaffinocytes, grow into the fetal cortex from side of abdominal aorta. In fetal cortex parenchyma chromaffin elements form cords, lobes, "medullary globes", which are enveloped by a basal membrane, which is a derivative of satellitocytes. Chromaffinocytes are stained with Wood's stain, potassium bichromate and, judging by the presence of secretory granules in their cytoplasm, are capable to synthesize summary catecholamines and to release them into the blood at the early stages of development. "Medullary globes" are the centers of proliferation and differentiation of the chromaffin cells in the adrenal medulla. The problem of chromaffin tissue stem cells is discussed.

Adrenal Glands↗
PubMed1998

Triggering of renal tissue damage in the rabbit by IgG Fc-receptor-positive group A streptococci.

Our previous studies have shown that streptococcal IgG Fc receptors (FcR) act to elicit circulating anti-IgG as well as renal glomerular deposition of IgG in rabbits immunized with group A streptococci (GAS). In order to study if other FcR-positive bacteria might have similar effects, rabbits were immunized with either group G streptococci (GGS; strain G148) or Staphylococcus aureus (strain Cowan I) for two periods of 8 and 6 weeks, respectively. At the end of immunization, circulating anti-IgG was found in 6 of 20 (30%) and 4 of 19 (21%) animals receiving G148 and Cowan I, respectively, compared to all 28 receiving FcR-positive GAS strains of types M1, M4, M15 or M22 (p < 0.05 for both comparisons); furthermore, anti-IgG appeared earlier and at higher levels in the GAS groups. Weak glomerular IgG deposits occurred in 5 out of 10 (50%) and 2 out of 8 (25%) animals immunized with G148 and Cowan I, respectively. In contrast, all 11 rabbits examined, given GAS of types M1 or M15, displayed heavy deposits. None of four control animals immunized with either of two FcR-negative strains, GAS type T27 or group B streptococci (GBS) type Ia, exhibited any renal IgG deposits or circulating anti-IgG. Renal tissue materials from rabbits immunized with any of the four FcR-positive GAS strains showed strong inflammatory and degenerative glomerular changes, compatible with the picture seen in acute poststreptococcal glomerulonephritis (APSGN). Only transient renal changes were found in those rabbits immunized with G148 or Cowan I, or the controls injected with the FcR-negative strains, GAS type T27 or GBS. Thus, only the FcR-positive GAS strains showed capacity to induce high levels of anti-IgG, pronounced tissue deposition of IgG as well as irreversible glomerular changes. Our experimental data suggest that streptococcal IgG FcR activity might play an important role in triggering APSGN.

Animals↗
PubMed1990

Haematological reactions of rabbits infected intravenously with Listeria strains of different virulence.

Listeria strains of different virulence were injected intravenously into rabbits of both sexes (2-4 kg). The infectious dose was 10(8) cells/kg. Blood samples were taken from the ear wein one day and immediately before the infection, then 3 h, 1, 2, 3, 6 and 10 days after it. Total white blood cell counts and their changes were determined and the number of lysosomal granules in neutrophils were counted. A marked monocytic reaction was observed after the injection of virulent Listeria monocytogenes 18 and 87/5467, partly virulent Listeria ivanovii, non-pathogenic Listeria seeligeri 87/5626 and 87/5575, and Listeria murrayi G44 strains. A late slow growth was provoked by Listeria innocua C644 and a very slight reaction by Listeria welshimeri 1830 strains. There was no change after injection of L. innocua strain 10. The number of lysosomal granules decreased significantly and remained at a low level for 6 days after the infection of L. monocytogenes strain 18 and for 3 days after the injection of L. innocua strain 10.

Animals↗
PubMed1986

[Method of staining for lysosomal cationic proteins in histological paraffin sections of biopsies].

A method is suggested for a histochemical and immunofluorescent detection of lysosome cation proteins in the histologic paraffin sections of biopsies. The method is based on the staining of histologic sections obtained from the material fixed in glutaraldehyde buffered with an alcohol solution of a fast green (pH 8.1-8.2) and on the detection myeloperoxidase and lactoferrine by means immune serum by Coons's method. 0.25% solution of azur A (B, C) is used for staining the cell nuclei and viable bacteria.

Biopsy↗
PubMed1986

[Detection of cationic proteins and peroxidase in semithin sections].

A method of histochemical identification of cationic proteins, peroxidase, viable and killed bacteria in semithin sections of biopsy samples is suggested. The method is based on dying of araldite-embedded semithin sections with a buffered alcohol solution of fast green (pH 8.15) and on peroxidase identification with O-dianisidine. The method suggested can be used for distinguishing occult forms of infectious gastritis, evaluation of secretory and barrier function of gastric epithelium, selective dying of leucocytes in tissues, revealing of viable and non-viable bacteria in the infective foci.

Adult↗
PubMed1981

[Study of enteric dysentery vaccines and their efficacy on a rabbit intestinal loop model. II. Changes in the mucosa of rabbit small intestine after oral immunization with live and chemical vaccines].

Ten days after oral immunization of 3 groups of rabbits with live vaccine prepared from the mixture of streptomycin-dependent mutants of Sh. flexneri 2a and Sh. sonnei, with Sh. flexneri and Sh. sonnei tryptic lysate, or with Boivin's extract of 6 Sh. flexneri and Sh. sonnei serotypes, a pronounced activation of the secretory and lysosomal apparatus was observed in ileac enterocytes. Deteriorating bacteria or their antigenic material was observed in ileac enterocytes. Deteriorating bacteria of their antigenic material was detected in phagolysosomas. An increased number of interepithelial lymphocytes, and mucous membrane lymphocytes (plasmoblasts and plasmocytes) was observed. The surface of the contact of lymphocytic cell membranes with enterocytes was also increased. It is suggested that special enterocytes with high pinocytic activity play an important role in the uptake and transport of antigenic material. The importance of the fact, previously unknown, that attenuated Shigella organisms are destroyed in enterocytic phagolysosomas is emphasized.

Administration, Oral↗
PubMed1981

[Oral intestinal vaccines and their effectiveness in the rabbit intestinal loop model. III. Effectiveness of oral immunization with live and chemical vaccines].

The effectiveness of the oral immunization of rabbits was manifested by a decrease in the number of virulent Shigella penetrating enterocytes, by the limited proliferation of bacteria in the epithelium and by the less pronounced ulcerous inflammation of the mucous membrane in the intestinal loops even after infection with large doses (10(9) bacteria). In electron microscopy this was manifested by the destruction of Shigella cells in heterophagosomes formed in enterocytes. The degree of fluid accumulation in the injected intestinal loops of immunized animals did not correlate either with the manifest morphological changes, or with the level of serum antibodies. The effectiveness of immunization was more pronounced after the introduction of smaller doses of virulent Shigella (10(7)-10(8) bacteria), when even Boivin's vaccine, though less effective, led to a decrease in the number of Shigella cells penetrating enterocytes, prevented their proliferation in the epithelium, its destruction and the development of inflammation.

Administration, Oral↗
PubMed1981

[Evaluation of the adhesion, colonization and enterotoxigenicity of Vibrio cholerae in the enteral infection of intact and passively immunized newborn animals].

V. eltor were introduced into 323 suckling rabbits through a gastro-duodenal tube and into 629 suckling mice either by the same method, or per annum by a new specially developed technique. Passive immunization was achieved in suckling mice by the preliminary introduction of antibacterial sera into the small intestine or by feeding them with the milk of female mice immunized at the end of pregnancy, and in suckling rabbits by feeding them with the milk of goats immunized by introducing vibrios through the tests of the udder. To evaluate the results, the accumulation of liquid in the intestine and the development of diarrhea were taken into account, quantitative inoculation of homogenized intestinal matter was made; vibrios on the epithelium of the villi in the small intestine were counted and the changes of enterocytes and the lamina propria, observed in light and electron microscopy, were considered. The results of the complex quantitative evaluation in intact suckling animals revealed that the enterotoxigenicity of vibrios was manifested after their adhesion to and later colonization on the intestinal epithelium. Passive antibacterial immunization suppressed their adhesion and colonization, which resulted in protection from the enterotoxigenic effect of vibrios and their elimination from the intestine.

Animals↗
PubMed1980

[Enteric dysentery vaccines and their effectiveness in a rabbit intestinal loop model. I. The residual virulence of attenuated vaccinal strains of Shigella administered into the intestinal loops].

Virulent Sh. flexneri strain 2a, Sh. sonnei strain, attenuated Sh. flexneri vaccine strain 2a 516M, and Sh. sonnei vaccine strain 6S (isolated by Yu. A. Belaya), as well as streptomycin-dependent Sh. flexneri strain 2a 1605/3 (isolated by V. V. Sergeev) were introduced into the ligated loops of the rabbit ileum. The use of light and immunofluorescent microscopy, the measurement of the volume of the fluid in the intestinal loops and the quantitative inoculation of their contents resulted in revealing the differences in the properties of the virulent and vaccine strains. The vaccine strains, in contrast to the virulent strains, did not proliferate in the lumen and did not cause the accumulation of fluid in the intestinal loops. They retained sharply limited, especially in the streptomycin-dependent bacteria, ability to penetrate into enterocytes and, via their cytoplasm, into the basement membrane, but lost their ability to proliferate in the cytoplasm of enterocytes (and probably even deteriorated there) and to cause plurulent ulcerous inflammation. This indicates that vaccine strains have insignificant residual virulence and suggests that the intestinal loop models, together with other models, may be used for testing the safety of vaccines prepared from Shigella strains.

Animals↗
PubMed1980

[Shigella interaction with immune enterocytes].

The immunity induced in rabbits by oral immunization with Boivin Shigella polyantigen results in activation of enterocytes: hypertrophy and dilatation of the Golgi apparatus and endoplasmic reticulum, increase in the number of sizes of primary and secondary lysosomes. Resistance of the immune enterocytes to Shigella is manifested in a decreased number of bacteria able to penetrate the cytoplasm, the absence of lysis of heterophagosome membrane surrounding the organisms, and the lack of fusion of the heterophagosomes with primary and secondary lysosomes. The bacteria are even destroyed in the immune enterocyte phagolysosomes. At the same time after the challenge of the rabbit gut loops with 10(9) Shigella some bacteria overcome the immunity, lyse the heterophagosome membranes and multiply directly in the enterocyte cytoplasm, as occurs in nonimmune control rabbits. As a result, ulcerative inflammation develops as in the controls, sometimes even accompanied by hypersensitivity reaction. Fluid accumulation in rabbit gut loops challenged seems to be associated with the effect of Shigella enterotoxin(s), both cytotoxic and cytotonic, as suggested by the peculiar manifestations of enterocyte hypersecretion and damage.

Animals↗
PubMed1977

[Interaction of cholera vibrios and escherichiae with the intestinal epithelium (histologic and electron microscopic study)].

Histological and electron-microscopic investigations were carried out of ligated small intestinal loops of 147 rabbits within 24 hours after challenge with cholera vibrios El Tor, different enterotoxigenic E. coli, choleragen and E. coli enterotoxins. These ogranisms attached themselves to enterocytes and multiplied on the surface of the unaltered intestinal epithelium. Thereafter, a greatly pronounced secretion of enterocytes, rather than inflammation, developed, like after the exposure to sterile enterotoxins of E. coli and choleragen, the lumen of isolated rabbit gut loops was overfilled with great amount of fluid discharged. At later period dystrophic alterations in enterocytes also appeared. They were partly associated with excessive secretion, but the severest of them (including even necrotic foci) were caused by the compression of the isolated gut loops epithelium with fluid. The first and obligatory stage of pathogenesis of cholera and cholera-like escherichioses was apparently the attachment of the causative agent to enterocytes and its multiplication on the intestinal epithelium surface, followed by hypersecretion induced by enterotoxin effect.

Animals↗
PubMed1977

Pathogenic effect of enterotoxigenic Escherichia coli and Escherichia coli causing infantile diarrhoea.

Macroscopic, light and electron microscopic alterations in ligated rabbit intestinal loops challenged with five standard enterotoxigenic Escherichia coli (ETEC) and twenty-three enteropathogenic E. coli (EEC-I) strains, freshly isolated from infantile enteritis cases, were investigated. Only two O26 : K60 : H11 strains produced enterotoxin. Their living cultures, sterile filtrates of the fluid medium and ultrasonic lysates of the bacteria resulted in pronounced hypersecretion of the intestinal epithelium followed by fluid accumulation and loop dilatation. These two E. coli strains, similarly as the other loop-negative EEC-I strains, were able to penetrate into the intestinal epithelium. In contrast to the standard ETEC strains, the EEC-I bacteria, adhering to the brush border, intruded into the microvilli, multiplied on the outer epithelial cell membrane making close contact with it and, causing, shedding of microvilli, penetrated into enterocytes becoming enclosed in membrane-bound phagosome-like vacuoles, appeared in the lamina propria and elicited mild focal polymorphonuclear infiltration.

Animals↗
PubMed1977

Interaction of vibrio cholerae El Tor and gut mucosa in ligated rabbit ileal loop experiment.

Light and electron microscope studies in ligated rabbit gut loops showed that cholera vibrios El Tor attached themselves to the enterocytes and multiplied, most probably on the intestinal epithelium surface. But they did not penetrate deeper and were unable to cause destruction of the epithelium or marked inflammation. Ultrastructural manifestations of both apocrine and merocrine secretion of the enterocytes were observed. In addition, the enterocytes showed signs of generally enhanced activity. Some other changes and alterations in the lamina propria, presumably induced by excessive transport of water, are also described. The enterotoxin-induced epithelial hypersecretion with fluid accumulation in the gut loops resulted in the attached vibrios being cleared off the epithelium lining into the gut lumen. NAG vibrios were mostly incapable of inducing the above changes. We discuss the importance of cholera vibrio attachment to and its multiplication on the intestinal epithelium in the pathogenesis of cholera.

Animals↗