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Biomedical subjects

K A Lebedev

Publications and source records attributed to K A Lebedev.

At least 55 records · Page 3Linked to original sources
PubMed1979

[Suppressing action of splenic cells on macrophage phagocytic activity].

The culture media withdrawn from 18-hour cultures of live spleen cells suppressed the phagocytic activity of peritoneal macrophages in mice. The level of suppression, as estimated for an equal number of spleen cells, varied in individual animals, which seemed to be connected with the level of normal infection in the animals. In the process of development of Ehrlich's carcinoma in mice suppressors were produced in the spleen in an increased amount, but only in connection with the total increase in the number of spleen cells, and not due to the selective accumulation of suppressor cells.

Animals↗
PubMed1978

[Action of embryonic thymus and liver cells on the development of the ascitic form of Ehrlich's carcinoma].

The influence of the cells of embryonic thymus and liver on the development of Ehrlich carcinoma was studied. The intraperitoneal injection of the embryonic cells in the adult mice infested by the Ehrlich carcinoma resulted in a marked lengthening of the life time of animals and an increase of the survival percentage. The embryonic cells of thymus and liver inhibited sharply the growth of carcinoma cells in the diffusion chambers as well. In contrast to this, the thymus and bone marrow cells of adult animals, taken in the same concentrations as the embryonic cells, exhibited only a slight inhibiting effect on the growth of tumour cells. On the basis of these data a suggestion is put forward to the effect that the embryonic immunocompetent cells determine the stronger inhibition of tumour growth in the embryos as compared with the adult animals.

Animals↗
PubMed1978

[Change in the density of surface lymphocyte receptors and in the level of serum immunoglobulins in chronic lympholeukosis].

Using the complex of methods for recognition of surface lymphocyte receptors the authors examined 42 patients with chronic lymphatic leukemia and 30 healthy individuals. The reduced density of receptors on lymphocyte surface or their total absence is characteristic of the whole group of patients with chronic lymphatic leukemia. This atypism of leukemia lymphocytes is augmented in greater rate of neoplastic cells growth. Total synthesis of serum immunoglobulins in chronic lymphatic leukemia is found to be lowered, the fall being more sharp in increased amount of lymphocytes in peripheral blood.

Adult↗
PubMed1977

[Quantitative characteristics of the T- and B-systems of immunity in healthy persons of different age groups].

The authors carried out a complex immunomorphological study of the peripheral blood lymphocytes in 160 healthy persons of different age groups. The tests of spontaneous and complementary rosette formation of lymphocyte blasttransformation with PHA were used, assessing it by the H3-thymidine incorporation, lymphocyte straining by Coon's direct and indirect methods for detection of surface immunoglobulin receptors; G, A, and M immunoglobulins blood serum content was studied by Mancini's method. Mean indices characterizing the T- and B-populations of lymphocytes in persons of different age were calculated on the basis of these studies.

Adolescent↗
PubMed1977

[Migration capacity of tumor cells treated with immune sera].

The action of antitumour sera on the adhesive properties of the L-cells and the cells of Ehrlich's ascitic carcinoma. It was shown that after the treatment with immune sera the tumour cells lost their capacity to form rosettes with sheep red blood cells, to adhere to plastics and glass; when administered into the mouse organism these cells were worse retained in the lungs, spleen and the liver. The data obtained indicated that the antibodies could play a significant role in the tumour cell metastasis.

Animals↗
PubMed1976

[Immunological indices in the digestive tract secretions in subcutaneous and oral vaccination against typhoid fever].

Volunteers were vaccinated subcutaneously and orally against typhoid fever; a determination was made of immunological reactions in the digestive tract secretions. Oral vaccination caused a much greater production of the secretory IgA than the subcutaneous one. Immunoglobulins of classes G and M were revealed in the intestinal contents only in a few volunteers. In studying the coprofiltrates obtained before the vaccination there was shown for the first time the presence of normal coproantibodies to typhoid fever, dysentery, tetanus, diphteria, botulism and gas gangrene; in the majority of the cases there was found a correlation between the presence of normal serum and secretory antibodies. Subcutaneous and oral vaccination caused an increase of coproantibodies specific for the vaccines used. Besides, the same vaccines stimulated the nonspecific response expressed in a rise of the level of other species of antibodies. Specificity of coproantibodies in the inhibitary passive hemagglutination reaction was demonstrated in the majority of the coprofiltrates examined.

Administration, Oral↗
PubMed1976

[Assessment of the quantity of T-lymphocytes and other rosette-forming cells in the blood of patients and healthy subjects].

In using the reaction of spontaneous rosette formation to assess the immunity T-system one should not limit one-self to determination of the percentage content of the rosette-forming cells alone. Immune status can be properly judged by determination of the content of immunocompetent cells per one cubic mm of the blood of the given donor. When the reaction is staged on the leukocyte suspension not only lymphocytes, but also other cell forms with the capacity of binding sheep erythrocytes can be determined.

Anemia, Aplastic↗
PubMed1976

[Repeated immune response in gnotobiotic rats].

Repeated immune response to diphtheria toxoid was investigated in monocontaminated rats. It was shown that repeated immunization of these animals led to a sufficiently intensive immune response by the secondary type, but it ended much earlier than in the usual animals (by the 12th day). A supposition is put forward that earlier termination of the secondary response in gnotobionts is caused by the absence in their lymph nodes of an additional differentiation of cell-precursors at the late periods of secondary immune response.

Animals↗
PubMed1976

[Globulin producing cells in cultures of blast-transformed lymphocytes in vitro].

Globulin-producing cells -- lymphocytes, transitional transformed forms, blasts and plasmocyte-like cells were revealed with the aid of Coon's method in the culture of the human peripheral blood following stimulation with staphylococcus filtrate and phytohemagglutinin. Analysis of dynamics of the appearance of these cells suggests that they originate from a special B-lymphocyte subpopulation -- the immunological memory cells. Some of the globulin-producing cells arose from precursors without any division, in others differentiation was combined with proliferation.

Adult↗
PubMed1975

[Characteristics of the immunomorphological substrate in secondary immunization as dependent on the functional state of the hypothalamic nuclei].

The authors traced the morphological and serological shifts occurring in secondary immunological response against the background of destruction of the posterior hypothalamic nuclei. It was revealed in experiments on rabbits that in primary and secondary immunization carried out against the background of bilateral coagulation of the posterior hypothalamic nucleus the secondary immunological response was reduced in comparison with control. Depression occurred both on account of reduction of the number of cells-precursors, and in connection with disturbances of differentiation of the antibody-forming cells. When the primary immunization was conducted against the background of the intact brain, and destruction of the posterior hyfothalamic nuclei preceded the secondary immunization there occurred a change in the number of cells-precursors involved in differentiation, without disturbance of the differentiation itself.

Animals↗
PubMed1971

Specific immune responses in changed gaseous environments.

The capacity of lymphoid cells to participate in immunity reactions was evaluated by blast transformation of lymphocytes under the influence of phytohemagglutinin. Blast transformation was measured by cytologic analysis and autoradiographic investigation of the rate of RNA synthesis in cells (tritiated uridin used as label). An analysis of the material taken from the three test subjects during the year-long experiment showed that various situations affected significantly the blast transformation level of lymphocytes. The reaction was substantially reduced 10 days after a simulated emergency situation which involved a change in the atmosphere, increase of physical load, etc. The level of blast transformation increased 1.5 to 2 months after the simulation, exceeding the average value, then to be normalized. Atmospheric variations appear to be one of the factors that may change the activity of lymphoid cells. A parallel experiment was performed in which three subjects lived 10 days in a hyperoxic enclosed environment (53% O2). They showed a considerable intensification of blast transformation (by 2.2-2.6 times) and pronounced activation of the RNA synthesis. Investigations give evidence that a long-term enclosure exerts an effect on the reactivity of the systems involved in the development of basic immune reactions.

Air Conditioning↗
PubMed1971

Shifts in the immunocompetence of lymphoid tissue in guinea pigs containing a limited microflora.

Many authors have demonstrated simplification of the species composition of the normal microflora in animals long kept in a closed environment. The purpose of the present work is to reveal the effect of such simplification (without reduction of the total number of bacteria) on the immunocompetent system of the animals. Three months old germ-free, monocontaminated (Staph. albus) and conventional guinea pigs with reduced fecal microflora were used in this study. Guinea pigs of the second group were fed a sterile diet but were kept in an ordinary vivarium. Two groups of control animals were: 1) conventionals fed regular diets; 2) conventionals fed the diet contaminated with fecal microflora of guinea pigs after sterilization. The fecal microflora was examined. The total number of bacteria in faeces of monocontaminated and microflora-reduced conventional animals was approximately the same as in conventional controls. Various lymphoid organs were examined. Their weight, size, number and activity of germinal centres, amount of globulin-producing cells, their differentiation and amount of globulins in single cells were determined. The lymphoid tissue in microflora-reduced animals and especially in monocontaminated guinea pigs was found to be underdeveloped. These changes were, however, less pronounced than in germ-free animals. It is suggested that simplification of the microflora in a macro-organism during long-term enclosure reduces the lymphoid tissue; such a macro-organism may develop severe reactions of the microbial shock, when occurring in a normal microbial environment.

Animals↗