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Biomedical subjects

D O Meshkov

Publications and source records attributed to D O Meshkov.

17 recordsLinked to original sources
PubMed2004

[Outcome of the long-term isolation on the development of allergic reactions in humans].

Studied were consequences of long-term isolation in airtight environment for development of the type-I (IgE-antibodies production) and type-IV (involvement of sensibilized T-lymphocytes) allergic reactions in humans. No significant changes in total IgE, specific IgE-antibodies for domestic, epidermal, fungal, grass pollen and food-borne allergens or serum IL-4 level were found in the period of the 240-d isolation with the microclimate and atmospheric parameters within their normal variations, and on completion of the experiment. Yet, after 3 mos. in isolation all subjects exhibited inhibited leukocyte migration in the presence of tuberculin. These findings bear witness to an activation of sensibilized lymphocytes known as effectors of delayed hypersensitivity.

Adult↗
PubMed2001

[Effects of the spaceflight factors on the immune system].

The paper summarizes the main trends and milestones of space immunology starting with initial ground-based investigations with animals to recent experiments in piloted and automatic space vehicles data of which have been highlighted in numerous publications. There is a brief description of lines and results of investigations with participation of cosmonauts, and using laboratory animals and cell cultures. The author dwells upon the present-day notion of immune responses to extreme conditions and future topics of investigations.

Antigens, Bacterial↗
PubMed2000

[Immunologic reactivity and status of the intestinal viral flora of humans in pressurized chambers].

Immunity status and intestinal viral flora were studied in 5 experiments with long-term exposure of 26 male subjects in pressurized chamber. In two experiments with congenital microclimate and gaseous environment cellular and humoral indices of immunity did not deviate from the physiological norm. None of 14 subjects in these experiments was identified as a virus-carrier. In three experiments with hard environmental conditions (elevated concentrations of ammonia and carbon dioxide) viruses were isolated from 8 out of 12 subjects. Activation of viral flora mainly occurred on a background of impaired immunologic reactivity. In two experiments carriage of virus was asymptomatic; in the third experiment with the rise of ammonia up to 7 mg/m3 two subjects developed clinic signs that could have been engendered by enteric viruses, the Coxsackie B strain specifically.

Adult↗
PubMed1999

[The diagnosis of disorders of the T-cell immunity component in space flight].

The investigation yielded two modifications of the procedure FOR determination of T-lymphocytes' functional activity in microsamples of the finger capillary blood and PHA-assisted cultivation of cells in syringe for subsequent morphological analysis by cosmonauts in flight. Testing of the proposed modifications in 14 healthy donors with unconstrained work/rest schedule, 4 volunteers in 60- and 6 volunteers in 120-day HDT showed a rather high comparability of data obtained with the modified and genuine procedures for determination of the T-lymphocytes proliferative activity in cosmonauts before and after orbital flights. Thus, the modified procedures can be successfully used for monitoring the immune status of cosmonauts on missions, and individuals exposed to extreme environments.

Cell Culture Techniques↗
PubMed1999

[Tuberculin-dependent and nonspecific migration activity of leukocytes in astronauts].

There have been presented the results of studying the reactivity of leucocytes with respect to tuberculin and monspecific migration activity of leukocytes in the cosmonatus pre flight and after completion of orbital expeditions of various duration are presented. In some cosmonauts tuberculin rearranged migration of leukocytes. This may bear witness to activisation of the immunity system in response to the antigens which had been already familiar to test-subjects. Experimental data pointed to significant changes in leukocyte mobility in 12 out of 28 cosmonauts examined on days 1 and 7-14 of recovery after the first or repeated long-duration space missions indicating some functional disorders in the phagocytic link which may lead to a typical decline in human resistance to infections.

Aerospace Medicine↗
PubMed1999

[Endogenous regulatory peptides, interferons and cytokines as adaptogens in exposure of the body to adverse environmental factors].

The authors summarize data on the efficacy of various prefabricated recombinant interferons against virus, bacterial, and chlamydial infections, and in unfavorable environments. The spaceflight factors were shown to have a negative influence on natural killers in the human body providing the immunological resistance and defence not only from foreign microorganisms but also the body cells transformed because of a virus infection or malignancy. Entalferon awakes a particular interest for its convenience in extreme conditions, space flight included. It is still an open issue whether the interferon sensitivity of natural killers is compromised by space flight. This trend of investigation seems to be of paramount importance and promise in the context of enhancing the antiviral, antimicrobic and antineoplastic immunity of cosmonauts.

Adaptation, Physiological↗
PubMed1998

Immune responses in extreme environments.

In order to identify some of these interactions and regulation between the immune system and other physiological variables we have investigated the immune status in extreme conditions such as long term isolation and confinement, strict antiorthostatic bed rest and spaceflight.

Allergy and Immunology↗
PubMed1998

[Human cellular immunity and space flights].

Results of studying cellular immunity of crew members of long-term space missions, data of an experiment with extended head-down tilting of human subjects (HDT), and data obtained in the course of adapting immunologic test methods for the use in microgravity are summarized. Disorders in immunologic reactivity were shown to occur under the conditions of space flight. They included decreases in both quantitative and functional indices of cellular immunity, and emergence of signs of sensibilization to different allergens. The modified tests were evaluated by efficacy of determination of the proliferative activity of lymphocytes in minimal volumes of capillary blood inside one-piece syringes with a medium containing PHA and the Cytodex-1 suspension, evaluation of natural cytotoxicity on the level of an effector cell (number of peripheral blood lymphocytes capable of producing conjugates with fixed target cells). Sensibilization to allergens of normal human microflora was tested in analogs of routine hematocrit capillaries used for examination of healthy donors under ordinary rest-work regimen. No significant differences between the standard and modified tests were revealed. The proposed test modifications are quite simple in use and require minimum of equipment.

Adult↗
PubMed1998

[Lipid peroxidation and antioxidative system in imitation diving].

Plasma lipid oxidation (LPO) and antioxidative system were examined in test divers who made imitation diving in the pressure chamber to the depth of 250 meters. Imitation diving showed higher iron levels, followed by a rise in the concentration of primary LPO products. There were no increases in the levels of secondary LPO products probably due to the fact that the ceruloplasmin-transferrin system released active iron from the reaction and that peroxy radicals were inactivated by SH groups.

Antioxidants↗
PubMed1998

[Carbohydrate adaptive substance for prophylaxis of immune disorders and correction of dysbacterioses].

Effects of a new preparation, adaptokhit, on the intestinal microbiocenosis and some parameters of immune resistance were studied in Macaque rhesus during 13-day hypokinesia. Experimental animals were given adaptokhit as an alimentary supplement preventing dysbiotic consequences of the microecologic unbalance due to motor restraint. Results of the investigation showed certain distinctions in the intestinal microflora in the experimental and control animals as early as on day three of the experiment. Intestinal microflora of the experimental primates who daily consumed adaptokhit at 50 mg/kg of the body remained stable throughout the period of observation. In contrast, in their controls lactoflora was found to decrease in parallel to the growth of opportunistically pathogenic endobacteria including representatives of Proteus and Clostridia sp., and development of dysbacteriosis of categories II and III. Besides, in the experimental animals adaptokhit prevented decline in the proliferative activity of lymphocytes further into adaptation. Also, at the final stage of observation following canceling the preparation there were signs of normalization of the allergologic status of primates in the experimental group. Therefore, adaptokhit can be used as an alimentary supplement to strengthen the colony resistance of animals in extreme conditions.

Animals↗
PubMed1998

[Migration capacity of phagocytes during simulation of some spaceflight factors under the terrestrial conditions].

Migration activity of the leukocytes featuring the functional state and metabolic activity of immunocompetent cells was studied. Migration of phagocyting cells was explored in 8 female test-subjects in the course of 120-day head-down bed rest and 3 male volunteers isolated in a hermetically sealed room over a similar period. Bed rest without use of preventive measures decreased significantly the migration activity of leukocytes; on the opposite, administration of the preventive measures by the bedrested subjects doubled the parameter. In the experiment with the long-term isolation the activity of leukocytes decreased significantly.

Bed Rest↗
PubMed1997

[Immune resistance of humans during extended isolation].

Analyzed were parameters of the immune reactivity and allergological status of participants in the 135-day chamber experiment with periods of induced psychoemotional strain. Stressful situations gave rise to shifts in the antibody system, i.e. decreased blood levels of ImgA, ImgM, and ImgG, decline in the functional activity of T-lymphocytes, suppression of the cytokinetic activity of lymphocytes-natural killers, and sensibilization to various allergens. Totality of these shifts resembles the ones which are typically seen during initial readaptation to the Earth's conditions on after long-term space mission.

Humans↗
PubMed1995

[Effects of space flight factors on production of oxygen radicals by phagocytes in cosmonauts].

In cosmonauts participated in space missions of various duration there changed one of the most important functions of phagocytes--the capacity to produce the active forms of oxygen during effect of corpuscular activator of zymosan. These changes depending on flight duration and individual peculiarities of cosmonauts manifested both as increase and decrease of the parameters studied. Family analysis of chemiluminescence of phagocytosing cells of the blood has revealed much importance of genotype in genesis of the variability of this function which points to the utility of an individual approach to evaluation of the immunity in cosmonauts.

Humans↗
PubMed1993

Immune changes in test animals during spaceflight.

Over the past two decades, it has become apparent that changes in immune parameters occur in cosmonauts and astronauts after spaceflight. Therefore, interest has been generated in the use of animal surrogates to better understand the nature and extent of these changes, the mechanism of these changes, and to allow the possible development of countermeasures. Among the changes noted in animals after spaceflight are alterations in lymphocytic blastogenesis, cytokine function, natural killer cell activity, and colony-stimulating factors. The nature and significance of spaceflight-induced changes in immune responses will be the focus of this review.

Animals↗
PubMed1992

Effect of spaceflight on natural killer cell activity.

The effects of spaceflight on immune cell function were determined in rats flown on COSMOS 2044. Control groups included vivarium, synchronous, and antiorthostatically suspended rats. The ability of natural killer cells to lyse two different target cell lines was determined. Spleen and bone marrow cells obtained from flight rats showed significantly inhibited cytotoxicity for YAC-1 target cells compared with cells from synchronous control rats. This could have been due to exposure of the rats to microgravity. Antiorthostatic suspension did not affect the level of cytotoxicity from spleen cells of suspended rats for YAC-1 cells. On the other hand, cells from rats flown in space showed no significant differences from vivarium and synchronous control rats in cytotoxicity for K-562 target cells. Binding of natural killer cells to K-562 target cells was unaffected by spaceflight. Antiorthostatic suspension resulted in higher levels of cytotoxicity from spleen cells for 51Cr-labeled K-562 cells. The results indicate differential effects of spaceflight on function of natural killer cells. This shows that spaceflight has selective effects on the immune response.

Animals↗