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Biomedical subjects

N K Tokarevich

Publications and source records attributed to N K Tokarevich.

At least 19 recordsLinked to original sources
PubMed2006

Anthropogenic effects on changing Q fever epidemiology in Russia.

In the northwestern region of Russia (Leningrad province) cattle is proved to be the main source of C. burnetii infection in humans, both in menaced professionals and in formally nonmenaced groups. Liquidation of specialized cattle-breeding complexes (with their well-organized veterinary surveillance) and broadening of the circle of non-professionals that contact with agriculture or domestic animals infected with C. burnetii provide the prerequisites to Q fever spreading among various groups of population.

Animal Feed↗
PubMed1994

Immunochemical and antigenic characterization of Coxiella burnetii strains isolated in Europe and Mongolia.

SDS-PAGE, immunoblotting and serological methods such as microimmunofluorescence (MIF) test and ELISA were used to compare protein and lipopolysaccharide (LPS) profiles and antigenicity of 12 Coxiella burnetii strains isolated mostly from ticks in Europe and Mongolia with three reference C. burnetii strains originating from USA, namely Nine Mile from tick, Priscilla from goat placenta and S from human heart valve. Among strains from Europe and Mongolia, no significant differences in protein and LPS profiles were observed, irrespective of their origin, i.e. the country and source of isolation. The LPS profiles of these strains appeared to be more related to those of Nine Mile strain associated with acute Q fever, than to those of strains S and Priscilla associated with chronic Q fever. In immunoblots all strains isolated from Slovakia and Poland reacted more expressively with rabbit serum against Nine Mile than with serum against Priscilla strain. In the MIF test and ELISA there were no substantial differences in antibody-binding capacity between the reference and newly isolated C. burnetii strains, except for strain Priscilla reacting with homologous serum in lower antigenic concentration than other strains under study. However, in the MIF test much higher antigenic concentrations of each C. burnetii strain was required to detect antibodies in the Priscilla serum than in the Nine Mile, Luga and S sera.

Animals↗
PubMed1994

[The comparative characteristics of the immunogenic and immunomodulating activity of different antigenic preparations of the causative agent of Q fever Coxiella burnetii].

The immunogenicity of the Coxiella burnetii corpuscle antigen and two its components, obtained after the treatment with chloroform-methanol or extraction by trichloroacetic acid, was investigated. All the studied antigens were highly immunogenic. A strong correlation was discovered between the immunogenic and immunomodulating properties of the C. burnetii antigens. Cells of the mononuclear phagocytic system are the targets for stimulating action of the studied antigens. A cyclic increase of antibacterial activity and oxygen-dependent metabolism of the peritoneal cells was noted, in addition to the increase of the natural splenocyte cytotoxicity caused by the action of these antigens. The role of cytokines in rising the activity of peritoneal cells and splenocytes, caused by immunization of mice with the above antigenic substances, is discussed.

Adjuvants, Immunologic↗
PubMed1993

[The dynamics of the metabolic and functional activities of the immunocompetent cells in mice following immunization with different vaccines against Q fever].

It was shown that the immunization of mice by the chemical Q fever vaccine prepared with the use of the strain "Coxiella burnetii, Nine Mile", phase I did not markedly activate the oxidative metabolism of the peritoneal exudate cells and did not induce the non-specific cytotoxicity in them. However, it resulted in a significant suppression of the mitogen-induced proliferation of splenocytes on days 3-5. The immunization of mice by the combined (corpuscular/chemical) vaccine prepared with the use of the strain "Apodemus flavicollis-Luga", phase I induced a significant activation of the oxidative metabolism of the peritoneal exudate cells and the development of the nonspecific cytotoxicity in them, whereas no suppression of the mitogen-induced proliferation of splenocytes was observed. The differences are likely associated with the presence of the corpuscular component in the combined vaccine and the strain antigenic specificity.

Animals↗
PubMed1993

Biological properties of chloroform/methanol extracts of Coxiella Burnetii.

Biological properties of antigens of whole cells of C. burnetii in phase I (WCI), their residue (CMR) and extract (CME) obtained by extraction of C. burnetti with chloroform/methanol mixture were subjected to a comparative study. It was shown that CME is able to react specifically with sera containing antibodies against WCI. The inoculation of animals with CME, but not with WCI and CMR does not cause changes of humoral and cell immunity to Coxiella and does not strengthen nonspecific antibacterial activity, but it can stimulate the formation of antibodies. Morphological changes of internal organs of mice were most expressed after the CMR inoculation and were practically absent after the CME inoculation.

Animals↗
PubMed1992

[The antimicrobial cationic proteins of the neutrophilic granulocytes in experimental Q rickettsiosis].

Blood of 56 guinea pigs with experimental Q rickettsiosis was studied cytochemically (lysosomal cationic test) to measure the level of cationic proteins in neutrophil granulocytes. Development of Q rickettsiosis resulted in a decrease in the killing ability of neutrophils, depending on infection dose introduced. However, by day 7 of the disease, the level of cationic proteins in blood neutrophil granulocytes returned to the initial range. Similar situation was noted after subcutaneous injection of Coxiella burnetti corpuscular antigen. Subcutaneous infection with the living culture stimulus induced the wave-like decrease of the cationic proteins content. Infection of pre-immunized animals led to smaller decrease in the cationic proteins levels and to their more rapid recovery. Aspects of antimicrobial activity of neutrophil granulocyte cationic proteins in experimental Q rickettsiosis is discussed.

Animals↗
PubMed1992

Dynamics of non-specific antibacterial activity of the peritoneal cells of mice induced with Coxiella burnetii antigen.

It was found that primary immunization with Coxiella burnetii antigen increased mouse resistance to Salmonella typhimurium infection as evidenced by acceleration of bacterial elimination from the peritoneal cavity and a decrease in lethality of experimental animals. The existence of two rises of bactericidal activity of mouse peritoneal cells was ascertained: the "early" on days 1 and 2, and the "late" on day 14 after C. burnetii administration. The first rise was accompanied by some increase in the number of peritoneal cells as well as by some change of their qualitative representation. The second increase of antibacterial activity was detected during the pronounced cellular and humoral immune responses to C. burnetii.

Animals↗
PubMed1992

Ultrastructure of viable and inactivated Coxiella burnetii after inoculation of mice.

C3HA mice were inoculated intraperitoneally (i.p.) with viable Coxiella burnetii (C.b.) (strain Apodemus flavicollis-Luga, phase I) or C.b. antigen (formalin-inactivated C.b.); pieces of spleen, liver, omentum, kidney, and suspension of peritoneal macrophages were examined by electron microscopy at 1, 7, 14, 21, 28, and 42 days post-infection (p.i.). Two main types of viable C.b. cells--small dense (DC) and bacteria-like (BC)--were found in omentum, spleen, and peritoneal exudate cells beginning from the 1st day p.i. but maximal amount they reached in spleen at day 14. Some parasitophorous vacuoles contained damaged BC or lysing C.b. cells. C.b. corpuscular antigen was found in phagosomes in ultrathin sections of spleen macrophages until 28 days p.i. By 7 days p.i. in omentum 3 types of parasitophorous phagosomes were described which were supposed to be the sites of the antigen utilization. It is assumed that most BC are destroyed in omentum macrophages during the 1st week after i.p. injection of the antigen, and DC can persist in spleen at least for one month.

Animals↗
PubMed1991

[The host reaction to the administration of different components of Coxiella burnetii].

After the intraperitoneal injection of corpuscles of C. burnetii antigen (Ag), phospholipid (PL), and sediment obtained after the extraction of PL from Ag with chloroform-methanol (CM) slight leukocytic reaction developed in the peritoneum on day 1, and on day 2 it could be observed in the liver and in the spleen. Ag induced the most pronounced morphological changes. In the spleen they were manifested by the activation of T- and B-dependent zones of white pulp from day 2 and by the pronounced hyperplasia of reticular cells and macrophages, leading to splenomegaly, by days 7-14. Simultaneously lymphoid-macrophagal granulomas and hepatomegaly developed in the liver. By days 7-14 the foci of necrosis in the liver were caused by the thrombosis of portal veins and were not registered after the injection of PL and CM (and earlier also in experiments with Ag in doses of 0.1-0.3 mg).

Animals↗
PubMed1991

[An immunoenzyme method for demonstrating Coxiella burnetii antigens].

Materials on the development of an enzyme immunoassay (EIA) system for the detection of the antigens of C. burnetii, the causative agent of Q rickettsiosis, are presented. The system is highly specific and effective with respect to both corpuscular antigens of phases 1 and 2 and soluble antigen (lipopolysaccharide). The sensitivity of this method varies within the range 5-100 ng/ml. The effectiveness of EIA as a quantitative (semiquantitative) control test used in the process of the production of Coxiella preparations has been demonstrated.

Animals↗
PubMed1990

Coxiella burnetii antigens may induce resistance to tumour growth.

Coxiella burnetii antigens stimulate the defence against growth of hepatoma 22a cells. The antigen-stimulated mice survived longer, they considerably later developed palpable tumours and showed a retarded tumour growth. The enhanced resistance to tumour growth may be explained by at least 2 interrelated phenomena; namely by the induction of interferon-like activity and an increased NK cell activity.

Adjuvants, Immunologic↗
PubMed1990

Indirect haemolysis test in Q-fever.

Sheep erythrocytes sensibilized with the lipopolysaccharide (LPS) extracted from Coxiella burnetii phase 1 cells were used in indirect haemolysis test (IHT). The test was highly sensitive and specific. Its use seemed reasonable when following the chronic course of Q-fever by serologic methods.

Animals↗
PubMed1989

[Immunogenic and immunomodulating properties of phospholipids from Coxiella burnetii].

It is proved that the challenging of the extract isolated from Coxiella (as a result of treatment with the mixture of chloroform and methanol) to animals doesn't provoke the appearance of antibodies to these microorganisms. It also doesn't cause the sensibilization of lymphocytes to Coxiella, but the extract can interact specifically with a serum containing antibodies to Coxiella. It permits to characterise the tested extract of Coxiella as a hapten with properties of adjuvant because it stimulates antibody-appearance.

Adjuvants, Immunologic↗
PubMed1989

[Detection of antibodies to Coxiella burnetii antigens using immunoenzyme analysis].

In trials the optimal conditions of immuno-enzyme analysis for detection of antibodies to Coxiella burnetii were revealed. It was proved that the sensitivity of ELISA exceeds the sensitivity of reaction of complement binding not less than in 100 times. The effectiveness of ELISA was shown to be higher than that of reaction of complement binding both at early terms of disease (up to 14th day) and in persons having the disease rather long ago (1-2 years ago).

Antibodies, Bacterial↗
PubMed1989

[Relapse of Q fever in childbirth and transmission of the pathogen to the child].

A case was described when a newborn was inoculated with Coxiella Burnetti as a result of infection relapse (in 8 months after acute disease) in his mother. Coxiella Burnetii were isolated from blood of both patients. Dynamics of humoral immunity indices in mother was observed both at the primary disease and during the period of infection relapse.

Antibodies, Bacterial↗