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At least 19 recordsLinked to original sources
PubMed1998

Immune responses in space flight.

Space flight has been shown to have profound effects on immunological parameters of humans, monkeys and rodents. These studies have been carried out by a number of different laboratories. Among the parameters affected are leukocyte blastogenesis, natural killer cell activity, leukocyte subset distribution, cytokine production - including interferons and interleukins, and macrophage maturation and activity. These changes start to occur only after a few days space flight, and some changes continue throughout long-term space flight. Antibody responses have received only very limited study, and total antibody levels have been shown to be increased after long-term space flight. Several factors could be involved in inducing these changes. These factors could include microgravity, lack of load-bearing, stress, acceleration forces, and radiation. The mechanism(s) for space flight-induced changes in immune responses remain(s) to be established. Certainly, there can be direct effects of microgravity, or other factors, on cells that play a fundamental role in immune responses. However, it is now clear that there are interactions between the immune system and other physiological systems that could play a major role. For example, changes occurring in calcium use in the musculoskeletal system induced by microgravity or lack of use could have great impact on the immune system. Most of the changes in immune responses have been observed using samples taken immediately after return from space flight. However, there have been two recent studies that have used in-flight testing. Delayed-type hypersensitivity responses to common recall antigens of astronauts and cosmonauts have been shown to be decreased when tested during space flights. Additionally, natural killer cell and blastogenic activities are inhibited in samples taken from rats during space flight. Therefore, it is now clear that events occurring during space flight itself can affect immune responses. The biological significance of space flight-induced changes in immune parameters remains to be established; however, as duration of flights increases, the potential for difficulties due to impaired immune responses also increases.

Animals↗
PubMedDate not supplied

[Enzyme activity of carbohydrate metabolism in rat skeletal muscle after space flight].

Space flight factors did not influence activity of glycogen phosphorylase and adenylate cyclase in skeletal muscles of rats. Activity of glucose-6-phosphate and 6-phosphogluconate dehydrogenases increased noticeably in the most active muscles (gastrocnemius and tibialis anterior muscles). Activation of enzymes involved in the pentosephosphate pathway of glucose conversion may be associated with compensatory processes induced by muscle changes due to diminished motor activity of animals in space flight.

Animals↗
PubMed2002

Red blood cell and iron metabolism during space flight.

Space flight anemia is a widely recognized phenomenon in astronauts. Reduction in circulating red blood cells and plasma volume results in a 10% to 15% decrement in circulatory volume. This effect appears to be a normal physiologic adaptation to weightlessness and results from the removal of newly released blood cells from the circulation. Iron availability increases, and (in the few subjects studied) iron stores increase during long-duration space flight. The consequences of these changes are not fully understood.

Adaptation, Physiological↗
PubMed1998

Nutrition, endocrinology, and body composition during space flight.

Space flight induces endocrine changes that perturb metabolism. This altered metabolism affects both the astronauts' body composition and the nutritional requirements necessary to maintain their health. During the last 25 years, a combination of studies conducted on Skylab (the first U.S. space laboratory), U.S. Shuttle flights, and Soviet and Russian flights provides a range of data from which general conclusions about energy and protein requirements can be drawn. We have reviewed the endocrine data from those studies and related it to changes in body composition. From these data it appears that protein and energy intake of astronauts are similar to those on Earth. However, a combination of measures, including exercise, appropriate diet, and, potentially, drugs, is required to provide the muscle health needed for long duration space flight.

Body Composition↗
PubMed2002

Gene expression in rat vestibular and reticular structures during and after space flight.

Space flight produces profound changes of neuronal activity in the mammalian vestibular and reticular systems, affecting postural and motor functions. These changes are compensated over time by plastic alterations in the brain. Immediate early genes (IEGs) are useful indicators of both activity changes and neuronal plasticity. We studied the expression of two IEG protein products [Fos and Fos-related antigens (FRAs)] with different cell persistence times (hours and days, respectively) to identify brainstem vestibular and reticular structures involved in adaptation to microgravity and readaptation to 1 G (gravity) during the NASA Neurolab Mission (STS-90). IEG protein expression in flight animals was compared to that of ground controls using Fisher 344 rats killed 1 and 12 days after launch and 1 and 14 days after landing. An increase in the number of Fos-protein-positive cells in vestibular (especially medial and spinal) regions was observed 1 day after launch and 1 day after landing. Fos-positive cell numbers were no different from controls 12 days after launch or 14 days after landing. No G-related changes in IEG expression were observed in the lateral vestibular nucleus. The pattern of FRA protein expression was generally similar to that of Fos, except at 1 day after landing, when FRA-expressing cells were observed throughout the whole spinal vestibular nucleus, but only in the caudal part of the medial vestibular nucleus. Fos expression was found throughout the entire medial vestibular nucleus at this time. While both Fos and FRA expression patterns may reflect the increased G force experienced during take-off and landing, the Fos pattern may additionally reflect recent rebound episodes of rapid eye movement (REM) sleep following forced wakefulness, especially after landing. Pontine activity sources producing rhythmic discharges of vestibulo-oculomotor neurons during REM sleep could substitute for labyrinthine signals after exposure to microgravity, contributing to activity-related plastic changes leading to G readaptation. Reticular structures exhibited a contrasting pattern of changes in the numbers of Fos- and FRA-positive cells suggestive of a major influence from proprioceptive inputs, and plastic re-weighting of inputs after landing. Asymmetric induction of Fos and FRAs observed in some vestibular nuclei 1 day after landing suggests that activity asymmetries between bilateral otolith organs, their primary labyrinthine afferents, and vestibular nuclei may become unmasked during flight.

Adaptation, Physiological↗
PubMedDate not supplied

Radiation: risk and protection in manned space flight.

Space radiation is the primary source of hazard for orbital and interplanetary space flight. Radiation levels for different space mission durations, have been established in order to determine the level of hazard. The risk of exceeding the established levels should not be more than 1%. Radiation environment models have been developed to estimate these values. It is possible to build spacecraft shielding based on the calculation of doses and the risk of exceeding these. By reviewing various calculated estimates of the risk, the radiation hazard and the efficiency of protective measures can be established for specific flights.

Aerospace Medicine↗
PubMed1993

Nutrition and human physiological adaptations to space flight.

Space flight provides a model for the study of healthy individuals undergoing unique stresses. This review focuses on how physiological adaptations to weightlessness may affect nutrient and food requirements in space. These adaptations include reductions in body water and plasma volume, which affect the renal and cardiovascular systems and thereby fluid and electrolyte requirements. Changes in muscle mass and function may affect requirements for energy, protein and amino acids. Changes in bone mass lead to increased urinary calcium concentrations, which may increase the risk of forming renal stones. Space motion sickness may influence putative changes in gastro-intestinal-hepatic function; neurosensory alterations may affect smell and taste. Some or all of these effects may be ameliorated through the use of specially designed dietary countermeasures.

Adaptation, Physiological↗
PubMed1996

Destruction of newly released red blood cells in space flight.

Space flight results in a rapid change in total blood volume, plasma volume, and red blood cell mass because the space to contain blood is decreased. The plasma volume and total blood volume decreases during the first hours in space and remain at a decreased level for the remainder of the flight. During the first several hours following return to earth, plasma volume and total blood volume increase to preflight levels. During the first few days in space recently produced red blood cells disappear from the blood resulting in a decrease in red blood cell mass of 10-15%. Red cells 12 d old or older survive normally and production of new cells continues at near preflight levels. After the first few days in space, the red cell mass is stable at the decreased level. Following return to earth the hemoglobin and red blood cell mass concentrations decrease reflecting the increase in plasma volume. The erythropoietin levels increase responding to "postflight anemia"; red cell production increases, and the red cell mass is restored to preflight levels after several weeks.

Adaptation, Physiological↗
PubMed2001

The biomedical challenges of space flight.

Space medicine has evolved considerably through past U.S. missions. It has been proven that humans can live and work in space for long durations and that humans are integral to mission success. The space medicine program of the National Aeronautics and Space Administration (NASA) looks toward future long-duration missions. Its goal is to overcome the biomedical challenges associated with maintaining the safety, health, and optimum performance of astronauts and cosmonauts. This program investigates the health effects of adaptation to microgravity: the nature of their pathologies, the effects of microgravity on pathophysiology, and the alterations in pharmacodynamics and treatment. A critical capability in performing research is the monitoring of the health of all astronauts and of the spacecraft environment. These data support the evidence-based approach to space medicine, incorporating past studies of microgravity-related conditions and their terrestrial counterparts. This comprehensive approach will enable safe and effective exploration beyond low Earth orbit.

Adaptation, Physiological↗
PubMedDate not supplied

[Lipid peroxidation and antioxidant defense system in rats after a 14-day space flight in the "Space-2044" spacecraft].

After 14-day space flight of rats onboard Cosmos 2044 in their blood plasma, homogenates of liver, skeletal muscles and myocardium there were determined the parameters of peroxide oxidation of lipids (POL) and system of antioxidant defense: content of dienic conjugates (DC), malonic dialdehyde (MDA), schiff bases (SB), tocopherol (TF), total antioxidative activity (AOA, only in plasma), activity of antioxidative enzymes (only in tissues) superoxide (SOD), catalase, glutathione-peroxidase (GP), glutathione-reductase (GR). In the animal liver there was a decrease in SB content and an increase of SOD, catalase and GP activities. Skeletal muscles exhibited a reduced SB concentration. In myocardium there was a reduction of DC and SB levels, activity of GR with an increase of TF concentration, activity of SOD and catalase. In the blood plasma there occurred a decline of SB and TF contents and an elevation of MDA and total AOA concentrations. The authors drew a conclusion about a compensated process of POL in the tested animals and about the relation of the observed changes with body response to the final phase of the space mission and acute gravitational stress during a readaptation to the Earth environments. On the basis of the analysis of similar data from shorter-duration space experiments, the noted changes in the parameters of the system of POL and antioxidant defense are considered a universal response which does not directly depend on duration of the orbital phase of a space mission.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of space flight factors on health of cosmonauts in the near and late term after space flights].

Cytogenetical studies of cosmonauts' peripheral blood lymphocytes after space flights on MIR orbital station showed a statistically significant increase in the yields of radiation-induced chromosomal aberrations. However, similar studies with in vitro irradiation of biological objects with accelerated charged particles are of great importance for elucidation of the nature of cytogenetical damage induced in vivo. It is also important to investigate the structure of cosmonatus' diseases over their life, in particular, lens opacities and oncological diseases. Thus, the purpose of the investigations planned is to study cytogenetical damage in blood lymphocytes from cosmonauts after space flights on the ISS in vivo, as well as in donor blood lymphocytes after in vitro exposure to accelerated charged particles. The tasks of the project are as follows: determination of the yields and types of chromosomal aberrations in cosmonauts' blood lymphocytes before and after space flights, comparative studies of biological effects induced in vitro by different types of ionizing radiation in human blood lymphocytes in ground experiments, assessment of cytogenetical risks, analysis of the structure of cosmonatus' diseases comparing with that of whole population, study of the mortality and frequency of cataracts and oncological diseases in cosmonauts. The results to be obtained will be used for setting of health norms applied to the influence of radiations of different types, and for elaboration of measures to reduce health risks from space flight factors.

Astronauts↗
PubMed1969

Vestibular analyzer as a critical organ in the evaluation of radiation hazards during space flights.

During space flights the vestibular analyzer functions under conditions which are not usual for Earth environments. The vestibular analyzer periodically or constantly experiences the action of angular, linear or Coriolis acceleration combined with ionizing radiation. The quantitative evaluation of the functional state of the vestibular analyzer made it possible to obtain material on semicircular canal activity disturbances at different periods of radiation sickness and responses of the irradiated body, given various doses of gamma radiation, to angular and Coriolis acceleration. Experiments were performed on 250 rabbits and 22 dogs. Rabbits were exposed to the total gamma radiation at doses of 50, 100, 500, 800, 5000, 10000 rad; dogs experienced single and fractional radiation exposures at doses of 200 rad (gamma-rays) and at doses of 500 and 350 rad (protons of 510 MeV). Specific conditions under which the astronaut's vestibular analyzer is functioning during space missions and our own experimental results make it possible to state that the vestibular analyzer serves as the critical organ in evaluation of radiation hazards during space flights.

Acceleration↗
PubMedDate not supplied

Autonomic regulation of circulation and cardiac contractility during a 14-month space flight.

The space flight of physician cosmonaut V.V. Polyakov, the longest to date (438 days), has yielded new data about human adaptation to long-term weightlessness. Autonomic regulation of circulation and cardiac contractility were evaluated in three experiments entitled Pulstrans, Night, and Holter. In the Pulstrans experiment electrocardiographic (ECG), ballistocardiographic (BCG), seismocardiographic (SCG), and some other parameters were recorded. In the Night experiment, only the ballistocardiogram was recorded, but a special feature of this experiment is that the BCG records were obtained with a contactless method. This method has several advantages, the most important of which are the possibility of studying slow-wave variations in physiologic parameters (ultradian rhythms) on the basis of recordings made under standard conditions over a prolonged period. The Holter experiment (24-hour electrocardiographic monitoring) used a portable cardiorecorder (Spacelab, USA). The obtained electrocardiographic data were used to analyze heart rate variability. In the first 6 months of the 14-month flight, the dynamics of cardiovascular parameters in V.V. Polyakov was virtually the same as in the other cosmonauts. The data obtained after the first 6 months of Polyakov's sojourn in space are unique and mention should be made of at least three important aspects: (1) activation of a new, additional adaptive mechanism in the 8th-9th months of flight, as is evidenced by alterations in the periodicity and power of superslow wave oscillations (ultradian rhythms) reflecting the activity of the subcortical cardiovascular centers and of the higher levels of autonomic regulation; (2) growth of cardiac contractility accompanied by a decrease in heart rate during the last few months of flight; (3) a considerable increase in the daily average values of absolute power of heart rate's variability MF component, which reflects the activity of the vasomotor center. Specific mechanisms of adaptation to weightless conditions appear to be associated with activation of higher autonomic centers. The hypothesis that central levels of circulation regulation are activated in a long-term space flight was investigated by analyzing of ultradian rhythms in nighttime. The data, received during the flight of V. V. Polyakov, show, that the process of human adaptation to long influence of weightlessness consists of a number of consecutive stages, during which the activation of more and more high levels of control system of physiological functions occurs.

Adaptation, Physiological↗