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At least 19 recordsLinked to original sources

PubMed1979

[Effect of weightlessness and artificial gravitation on thyroid gland morphology].

The investigation of the thyroid gland was carried out in Wistar rats, SPF colony 4.5--13 h and 25 days after a 18.5 days flight on board the space biosatellite "Cosmos-936". In animals subjected to weightlessness, moderate symptoms of the thyroid hypofunction were observed, statistically significant decrease in number and volume of the nuclei in calcitonin-secreting cells (C-cells) was especially pronounced during 4.5--9 h after landing. Similar but less pronounced changes were observed in C-cells of the rats subjected to artificial conditions of space flight, besides weightlessness. The similarity of the changes in the animals of both groups made it possible to connect the increasing amount of C-cells and the morphological symptoms of their functional inhibition with the effect of weightlessness and hypokinesia. During the space flight, the animals were kept under the conditions of artificial gravitation on board the biosatellite and therefore morphological peculiarities specific for the earth conditions were preserved in C-cells and the thyroid gland. Thus, it was concluded that artificial gravitation prevented the development of the thyroid changes which appeared under the influence of weightlessness.

Animals↗

PubMedDate not supplied

[Chief methods of modeling the biological effects of weightlessness].

The paper describes basic principles related to weightlessness simulation. In ground-based experiments zero-g is simulated with respect to the conceptual mechanisms of weightlessness effects on the body. The main components of the effects are considered to be elimination of deformations and fluid redistribution. The paper surveys and summarizes different methods of weightlessness simulation. It discusses advantages and disadvantages of water immersion, prolonged bed rest, hypokinesia, suspension in special devices with many degrees of freedom, walking on a treadmill at different angles, etc. The paper describes simulation of accentuated individual effects of zero-g during an exposure to longitudinal acceleration. It presents experimental physiological methods of simulation and symptoms of zero-g effects under normal laboratory conditions. The paper emphasizes inadequate use of some simulation techniques.

Bed Rest↗

PubMedDate not supplied

[Use of freeze-dried products in weightlessness].

The paper describes the manufacture of food products that can be eaten in weightlessness with the aid of regular table-ware. The consistence of products was altered as a result of an addition of water or modified starch. The resultant products were tested during short-term weightlessness aboard the aircraft-laboratory TU-104A. It was demonstrated that in weightlessness products having sufficient viscosity can be eaten with the help of regular table-ware. An addition of thickening agents, e. g. modified starch, helped to obtain products with necessary properties.

Cooking and Eating Utensils↗

PubMed1978

[Comparative study of the lymphoid organs of rats aboard a space flight under weightless and artificial gravity conditions].

A comparative histological investigation of the thymus, spleen and inguinal lymph nodes has been performed in the rats flown for 18.5 days on board the biosatellite "Cosmos-936" under the conditions of weightlessness and artificial gravitation (acceleration 1 g) imitating terrestrial magnetism. It has been stated that in the animals that were under the conditions of weightless ness during the flight and were sacrificed 4.5--13 h after they have landed the Earth, accidental involution of lymphoid organs is noted with morphological signs in them of an acute stress in the form of massive degeneration of the thymus lymphocytes and neutrophilic infiltration of the spleen. In rats that during the flight were subjected to the effect of artificial gravitation there was noted neither involution of the lymphoid organs nor morphological signs of acute stress in them. One of the main cause of acute stress in the rats subjected to weightlessness during the space flight is supposed to be transition to the terrestrial gravitation.

Animals↗

PubMed1977

Discussion of the combined effect of weightlessness and ionizing radiation on the mammalian body: morphological data.

The combined effect of weightlessness and ionizing radiation, from the Cs137 source at 800 rads for 24 h, on the animal body was studied. The morphological examination of organs and tissues of rats flown aboard the biosatellite Cosmos-690, kept in the ground-based simulation experiment, and kept in the vivarium, indicated prevalence of radiation-induced changes in both experimental groups of rats. An exposure of animals to space flight factors did not produce a substantial aggravation of radiation-induced effects. This is indicated by the lack of significant differences in the weight of testes, thymus, and spleen of flight and simulation rats. However, this exposure affected adversely the development of reparative processes in the hemopoietic tissue of bone marrow. Inflight irradiation aggravated weightlessness-induced changes. A combined effect of weightlessness and irradiation did not result in the summation of the effects exerted on skeletal muscles by either factor alone.

Animals↗

PubMed1976

Effect of penetrating radiation on skeletal muscles of rats in weightlessness.

The isoenzyme composition of lactate dehydrogenase of soleus and plantaris muscles of rats flown for 20.5 d aboard the biosatellite Cosmos-690 and irradiated with a dose of 800 rad was investigated. The muscles exposed to weightlessness per se and weightlessness combined with radiation showed similar changes in their carbohydrate metabolism. On return to 1 G, readaptation of irradiated rats developed less rapidly than of animals exposed to weightlessness alone.

Animals↗

PubMed1979

Radiographic comparison of human lung shape during normal gravity and weightlessness.

Human lung shape was measured during zero gravity (0 G) to decide whether the normal vertical regional differences in ventilation are due directly to distortion of the elastic lung by its own weight, or instead, due indirectly to the effect of gravity on the shape of the rib cage and diaphragm. This was important because we previously established that weightlessness virtually abolishes the normal topographical inequality of ventilation (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 45: 987-998, 1978). Chest radiographs were made after 10 s of a weightless flight trajectory aboard a NASA-Ames Research Center Learjet in both posterior-anterior and left lateral projections on five seated volunteers at residual volume, functional residual capacity, and total lung capacity. Lung shape was assessed by measuring lung heights and widths in upper, middle, and lower lung regions. We found no significant differences between any of the normal gravity (1 G) and o G measurements, although there was a slight tendency for the lung to become shorter and wider at o G (mean changes generally less than 3% or about 0.5 cm). By contrast, Grassino et al. (J. Appl. Physiol. 39: 997-1003, 1975) found no change in the vertical distribution of ventilation after voluntarily changing lung dimensions by more than 1 cm by moving the abdomen in or out. We conclude that gravity produces the topographical distribution of ventilation in the upright human lung by distorting the elastic lung tissue within the chest rather than by altering the shape of the rib cage and diaphragm.

Humans↗

PubMed1977

Weightlessness and gravitational physiology.

Physiologic responses to the weightless environment have been documented in Skylab astronauts. Significant changes in cardiovascular responses, calcium metabolism, fluid distribution, and red blood cell mass are described. Although the data are limited and the sample size small, several hypotheses can be formulated. Future studies in a space laboratory setting offer the potential for understanding the effects of weightlessness on human physiology and the implications to medicine.

Action Potentials↗

PubMedDate not supplied

[Combined action of weightlessness and ionizing radiation on the body of rats (based on data from morphological studies)].

The combined effect of weightlessness and ionizing radiation (24 hour exposure to Cs-137 at a total dose of 800 rad) was investigated morphologically in Cosmos-690 flight, synchronous and vivarium rats. Irradiation-induced lesions prevailed in both groups of rats. Comparative study of changes in flight and control rats showed that weightlessness and other space flight factors did not induce any new, previously unknown effects as compared with the exposure on the Earth; they did not exert a significantly aggravating effect on the development of radiation-induced lesions.

Adrenal Glands↗

PubMed1978

Distribution of pulmonary ventilation and perfusion during short periods of weightlessness.

Information on the distributions of pulmonary ventilation and perfusion was obtained from four subjects on board a Learjet during 112 weightless periods lasting up to 27 s each. Zero gravity (G) was obtained during all or part of each test by varying the aircraft flight profile. Single-breath N2 washouts were performed with the test inspiration containing an initial bolus of argon at residual volume (RV). When the test inspiration was at 0 G, and the washout at 0 G or greater, the terminal rises and the cardiogenic oscillations in both N2 and argon were small and often absent. If instead the test inspiration was at 1 G with the washout at 0 G, the terminal rises were again small or absent but the cardiogenic oscillations remained. The terminal rise and the cardiogenic oscillations for N2, but not argon, were also nearly eliminated by performing just the preliminary exhalation to RV at 0 G with the test inspiration and washout following at 1 G. Aleveolar plateaus for N2 sloped upward at 0 G apparently due to nontopographical inequalities of ventilation. In further tests during air breathing, recordings were made of expired partial pressure of oxygen PO2) and carbon dioxide (POO2) following a brief hyperventilation and a 15-s breath hold. These recordings revealed marked cardiogenic oscillations in PO2 and PCO2 at 1 G that were enhanced at 2 G but almost eliminated at 0 G. The results suggest that virtually all the topographical inequality of ventilation, blood flow, and lung volume seen under 1-G conditions are abolished during short periods of 0 G.

Adult↗

PubMedDate not supplied

The structural and functional organization of the vestibular apparatus of rats exposed to weightlessness for 20 days on board the Sputnik "Kosmos-782".

This investigation of the vestibular apparatus of rats exposed for 20 days to weightlessness on board an earth satellite and to acceleration during take-off and landing has revealed a set of changes in the structural and functional organization, such as adjoinment of the otolith to the utricle receptor surface and peripheral localization of the nucleoli inside the receptor cells' nuclei. Destruction of some receptor cells, apparently due to increased swelling of the vestibular apparatus tissue and alteration of the shape and structure of the otoconia were observed. In the horizontal crista, detachment of the cupula took place.

Acceleration↗

PubMed1978

[Structural and functional organization of the vestibular apparatus in rats maintained under weightless conditions for 19.5 days aboard the satellite "Cosmos-782"].

Vestibular apparatus was investigated in rats subjected to weightlessness for 19.5 days in the satelite "Cosmos-782" and experienced acceleration on launching and landing. Some structural and functional changes were noted. They were seen in otolith clinging to the utricular receptor surface and in the peripheral arrangement of the nucleolus in the nuclei of the receptor cells. It is also possible that increased edema of the vestibular tissue resulted in destruction of some receptor cells, and within the otolith--changes in the form and structure of otoconia. In the horizontal crista the cupula was separated.

Acceleration↗

PubMed1978

Effect of prehatching weightlessness on adult fish behavior in dynamic environments.

At 16-17 months of age, three groups of fish from the embryonated eggs in the ASTP killifish experiment were subjected to postflight tests consisting of rapidly changing environments. It was found that the group of fish with the least amount of development at orbital insertion (A-32) had a decreased rheotropism for both the moving background and the rotating water current tests when compared to ground control fish. Exposure to parabolic aircraft flight conditions revealed that the A-32 fish were less disoriented during zero gravity periods and were hypersensitive to high-gravity periods. These results suggested a modified vestibular competency due to a 9-d prehatching weightlessness exposure.

Adaptation, Physiological↗

PubMed1979

Ultrastructural development of the vestibular system under conditions of simulated weightlessness.

Electronmicroscopy was used to track the development of the gravity system of frog embryos and larvae which have bred for 5, 7, and 10 d after egg fertilization under conditions of simulated weightlessness on the fast-running horizontal clinostat. Although no differences in the morphologic structure of the organ between test and control animals could be found up to 7 d of development, there is a significant accumulation of vacuoles in sensory epithelia of frog larvae develpoping for 10 d (stage 17) in simulated zero G.

Animals↗

PubMedDate not supplied

[Current concepts concerning the genesis of vestibulo-vegetative disorders in weightlessness].

The up-to-date hypotheses of the genesis of vestibulo-vegetative disorders in weightlessness are taken under critical analysis. Preference is given to the concept which attaches greatest importance to the changes in stereotyped interactions of analyzers responsible for space perception. It is, however, emphasized that neither hypothesis can account for all the phenomena seen in crewmembers in orbital flight. It is, therefore, indicated that mechanisms of vestibulo-vegetative disorders need further study. It is believed that the most promising line of research is to study the role of endogenous factors determining individual variations of motion sickness susceptibility.

Autonomic Nervous System↗

PubMedDate not supplied

[Antiorthostatic hypokinesia as an approximate model of weightlessness].

Eight test subjects were exposed to a five-day bed rest experiment in the recumbent and head-down position (at an angle of 0 degrees,--4 degrees,--8 degrees, and--12 degrees) to study the physiological effects of the exposure. The head-down tilting at--4 degrees and--12 degrees was shown to simulate physiological effects of real space flight better than bed rest at 0 degrees. The results made it possible to model an acute stage of weightlessness adaptation and to assay the contribution of gravity-induced blood redistribution to the physiological reactions.

Adult↗

PubMed1978

[Characteristics of the microcirculatory bed of the gastrocnemius muscle of rats under conditions of weightlessness].

Quantitative histological investigations of capillaries in the gastrocnemius muscle of rats after 18.5 days on board the artificial satellite "Cosmos-936" have demonstrated that the number of functioning capillaries decrease by about 30% under conditions of weightlessness. Decrease in the number of functioning capillaries in the gastrocnemius muscle is also observed in animals subjected to artificial gravitation (acceleration 1 g) during the flight. The main role in lowered blood supply of the muscles is supposed to play the lack of kinetic but not static loading on the muscles.

Animals↗

PubMed1977

The urinary excretion of collagen degradation products by quadriplegic patients and during weightlessness.

Urinary total hydroxyproline, peptide-bound hydroxyproline, hydroxylysine glycosides, and calcium were measured in three healthy individuals subjected to weightlessness for eighty-four days and in three young quadriplegic patients. The former group had significant calciuria but no evidence of collagen degradation. The latter group, however, had conspicuous calciuria and also excreted large amounts of collagen breakdown products. This documented degradation of matrix may be related to the continuous calciuria, osteoporosis, and cutaneous dystrophic changes occurring in quadriplegics.

Calcium↗