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PubMedDate not supplied

[Differences in growth and ontogenetic development of plants grown in the Earth gravitational field in the natural and inverse orientation].

Wheat plants Triticum aestivum L., Apogee cultivar, were grown in the natural and inverse orientation of the Earth gravitational field. Special vegetation containers with double bottom were used for the cultivation. The upper bottom made of porous titanium served as a hydrophilic porous membrane stabilizing aquatic potential in the root-inhabited zone at a given level. Normal plants yielding viable seeds were obtained for both natural and inverse orientation. In our experiments, the inverse orientation induced dry weight accumulation by the plants as well as development of productive tillering shoots and increased the shoot-root dry weight ratio.

Earth, Planet↗
PubMed2003

A critical period for gravitational effects on otolith formation.

The otoliths of adult animals do not change significantly during space flight. However, during the period when otoliths are first developing, rearing in space produces significantly larger otoliths. Conversely, animals reared on a centrifuge have smaller than normal otoliths. To identify a critical period during development for gravitational effects on otolith growth, fertilized zebrafish (Danio rerio) eggs were reared on a centrifuge for 1 week. The fine structure of their inner ear during development was studied by both light- and transmission electron microscopy. By 16 hours after fertilization (1-g, at 28.5 degrees C), precursors of the otoliths are seen but no sign of a sensory epithelium is present. Mature hair cells, appearing capable of mechanotransduction, are not seen until between 48 and 72 hours after fertilization. Zebrafish reared at 3-g from 1 to 7 days after fertilization exhibit significantly slower otolith growth than did 1-g controls. Fish exposed to 3-g only from 12-36 h after fertilization had slightly smaller otoliths than 1-g controls, but this difference was not significant. Animals exposed to 3-g from 36 h to 7d after fertilization did have significantly smaller otoliths. If the fish use their hair cells to assess otolith weight in a regulatory role, the hair cells would have to be functional. Thus the earliest stage zebrafish, which were not significantly affected by centrifugation, probably did not have an adequate means of sensing otolith weight to "correct" for the excess weight.

Animals↗
PubMed1978

Gravitational lumbar traction.

Low back and extremity pain is often secondary to inflammation of the nerve root or sinuvertebral nerve. Gravitational lumbar reduction therapy may relieve such pain. The results in a series of 121 cases are presented.

Back Pain↗
PubMed2004

Mechanisms of the gravitational sensitivity of cells.

It is well known that specialized gravireceptory cells have been formed in the course of evolution in the majority of multicellular organisms. These are statosytes (statenchyme cells) in higher plants and otolith apparatus cells in animals. The mechanisms of gravity reception and the generation of gravitational stimuli in these cells are well understood. Therefore, our attention was focused on cells devoid of special gravireceptory mechanisms, namely cell cultures grown in vitro (fibroblasts and osteoblasts) and unicellular free-swimming (i.e. possessing a locomotor apparatus) organisms. These were mainly representatives of two classes: Ciliata and Flagellata. The choice of the objects of study was mainly determined by their ecological and physiological characteristics with the main goals of this work.

Animals↗
PubMed1991

[Effect of blood gravitation surgery on lipid metabolism in patients with ischemic heart disease].

Gravitation plasmapheresis (GP) used in coronary heart disease patients with unstable angina pectoris of the III-IV functional class, in the presence of dyslipoproteinemia, leads to a significant decrease of high levels of cholesterol (Ch), triglycerides (TG), cholesterol in low-density lipoproteins (Ch-LDLP) and an increase of cholesterol in high-density lipoproteins (Ch-HDLP) followed by gradual recovery of these parameters up to the initial level in the whole group of patients during 6 months of observation. In patients with dyslipoproteinemia (DLP), types IV and II A, the initial level was recovered earlier (during one month), in those with type II B--after 6 months, although the levels of Ch and TG were high, that does not exclude the presence of progressing coronarosclerosis. The duration of clinical remission comprised on the average 7.4 months, in patients with type II A it was 5 months, with type IV--6.5 months. It has been suggested that pathogenetic features of DLP types formation are responsible for varying effects of GP on different types of DLP.

Coronary Disease↗
PubMed1991

[The use of gravitational plasmapheresis in hepatology].

The experience with the use of gravitation plasmapheresis in treatment of patients with jaundice of different genesis is summarized. A technique for performance of plasmapheresis in patients with parenchymatous and obstructive jaundice, number of the manipulations performed, volume of plasma removed, dynamics of normalization of the biochemical indices of the blood of the patients are presented.

Gravitation↗
PubMedDate not supplied

[Gravitational sensitivity of eukaryotic unicellular organisms].

Unicellular organisms are viewed as the best suitable objects for studying environmental effects, including the field of gravity, on living beings at the cellular level. Investigations of unicellular free-living eukaryotic organisms in gravitational and space biology help resolve both theoretical problems and practical problems associated with the design and development of biological life support systems. This paper presents experimental data about the effect of hypergravity on the structure, function and behavior of unicellular organisms--Tetrahymena pyriformis and Euglena gracilis. They were centrifuged at a rate of 87, 108 or 142 rpm to produce acceleration of 2, 3 or 5 G. The following parameters were measured: time course variations in the culture growth, rate of biomass accumulation, cell shape and size. It was found that as the gravity level grew from 2 to 5 G the culture growth was first stimulated and then inhibited. Biomass accumulation as well as the cell size and volume of Tetrahymena pyriformis and Euglena gracilis also decreased. It was demonstrated that the functional activity of cells was inversely proportional to the gravity magnitude. Potential mechanisms of the effect of hypergravity on the cell structure and function are discussed.

Animals↗
PubMedDate not supplied

[Effect of position with respect to gravitational force on the hydrodynamics of an experimental model of saccular aneurysm].

We wish to confirm the hypothesis that the hydrodynamics of brain aneurysms depend partially on their position, with respect to the force of gravitation, and so developed an experimental model of latex aneurysms, which was subjected to a pulsatile flow. Four different registers were made with an injection of ink and radioisotopes. A physical model was designed which allowed a quantitative analysis of the results and which allows a mathematical analysis of the aneurysm's hydrodynamics. The results suggest that when an aneurysm is oriented against the force of gravity, it has a very low risk of thrombosis, and the scarce turbulence of the flow condition a lower risk of growth and rupture, in comparison with other conditions. The greatest flow turbulence against the wall is found in the aneurysm oriented downwards, that is parallel to the force of gravity. Due to its hydrodynamics, the downwards aneurysm has the highest probability of complication, since it has; a) higher risk of rupture due to the impact of the stream upon the wall and to the turbulence this impact produces, b) a higher risk of thrombosis produced by the circulatory stasis which has a dome. This combination of factors (rupture and thrombosis) allows these aneurysms to grow more than others.

Gravitation↗
PubMedDate not supplied

[A computer-assisted study of the effect of gravitation on the functional state of the lungs].

Gravitation influence on lung function was investigated in 115 patients and 21 healthy persons. Changing of an examinee's position from vertical into a horizontal one causes changes in lung function in health and disease. Characteristic features of lung function were determined for each group of examinees in order to improve the diagnosis and differential diagnosis of bronchial cancer and nonspecific chronic pulmonary diseases with a similar x-ray picture. A study of pulmonary ventilation and blood supply of the lungs in vertical and horizontal postures in Hodgkin's disease patients led to a conclusion that irradiation of patients seemed more effective in a phase of deep breath. It made it possible to reduce radiation exposure of healthy parts in a zone to be irradiated.

Adolescent↗
PubMedDate not supplied

[Effect of weightlessness on the functions of perception and the reproduction of gravitational vertical in response to optokinetic stimulation].

In weightlessness spatial orientation largely depends on coordinated interaction of sensory systems involved in static orientation. The purpose of the present study was to quantify perception of spatial coordinates in response to optokinetic stimulation. Effects of weightlessness were simulated by dry water immersion hypokinesia. A custom-made optokinetic stimulator equipped with a device to measure perception of the gravitational vertical in response to optokinetic stimulation was used. A special platform with rubber bungee cords was employed to determine the role of the proprioceptive afferent input. It was demonstrated that during immersion day 1 the angle of erroneous perception of the vertical line consistently increased. By immersion day 3 the angle diminished suggesting adaptive developments. Additional proprioceptive inflow during immersion reduced significantly the error of perception. These findings indicate that the proprioceptive afferent input plays an important role in the mechanisms of spatial orientation at an early stage of exposure to weightlessness.

Adult↗
PubMed1987

[Effect of gravitation plasmapheresis on central hemodynamics and indices of myocardial metabolism in patients with acute complicated myocardial infarct].

A study of 32 patients with complicated acute myocardial infarction, treated with gravitation plasmapheresis during the acute phase of the disease, demonstrated a significant drop in blood concentrations of compounds with high molecular weights (fibrinogen, cholesterol, triglycerides, total protein) as well as a significant activation of the heart's pumping function, while total peripheral resistance declined, as did the degree of myocardial ischemia. This is interpreted as an evidence of positive effect of plasmapheresis on central hemodynamics, myocardial metabolism and clinical course of myocardial infarction in such patients.

Aged↗
PubMedDate not supplied

[Use of gravitational loads as a screening method in research on new biologically active substances].

The application of longitudinal gravitational overloads in white rats in craniocaudal and caudo-cranial directions modelled on a centrifuge is suggested for the screening of bioactive agents. The time and value of the overload are selected in such a way, as to kill 50% of animals in the control experiments. The same overload is given to animals that have previously received the tested agents. The difference in the survival rate of these animals and the control ones serves as the indicator of activity of the new compounds. This method reflects mainly the functional stability of the system of cerebral circulation.

Acceleration↗
PubMedDate not supplied

[Effect of dibasol and several of its imidazo-analogs on the resistance of animals to gravitational overloading and the dynamics of the development of post-ischemic cerebrovascular phenomena].

Anesthetized and nonanesthetized animals (white rats and cats) were used to study the effect of dibasol and its new imidazo analogs (designated AKS-67 and AKS-87) on animal tolerance to gravitational effects and cerebral ischemia (ligation of both carotid arteries) as well as on systemic arterial pressure and tone of cerebral and peripheral vessels (resistographically) in the postischemic period. The drugs were administered 30-90 min before exposure. It was found that in nonanesthetized rats dibasol and AKS-87 increased tolerance to cranio-caudal acceleration and decreased it to caudo-cranial acceleration, whereas AKS-67 produced a distinct protective effect regardless of the vector. In anesthetized rats (bilateral carotid ligation) AKS-67 and AKS-87 increased acceleration tolerance and dibasol produced no protective effect. Dibasol enhanced postischemic hypotension while AKS-67 and AKS-87 delayed or completely arrested it. For aerospace medicine the drug AKS-67 is of particular importance because it increases significantly animal tolerance to acceleration and stabilizes arterial pressure in the postischemic period.

Animals↗
PubMed1979

[Several morphologic changes in the blood vessels of the rabbit medulla oblongata arising under the influence successive exposure to gravitational overloading and hypokinesia].

Morphological changes in blood vessels of the rabbit medulla oblongata were studied after successive effects of maximum-bearing gravitational overloadings of 10 units applied at different directions and hypokinesia of various duration. Blood system of 35 rabbits was injected with Gerota's mass, cleared horizontal sections of the medulla oblongata 120 mkm thick were stained with hematoxylin--eosin and after Van Gieson. The experiments demonstrated various, quantitative and qualitative, changes in the vessel structure of the medulla oblongata, prevalence of one of the factors applied--in one combination and successive application; total resulting effect of overloading and hypokinesia--in the other combination; peculiar morphological changes unusual to any of the two factors--in the third combination. It was also demonstrated that readaptation for 12 weeks resulted in a significant restoration of the blood vessel structure in the rabbit brains preliminarily subjected to a successive effect of hypokinesia for 4 weeks and overloading in cranio-caudal directions.

Adaptation, Physiological↗
PubMedDate not supplied

[Effect of small gravitational loads on human water-salt metabolism and kidney function during prolonged immersion].

It was demonstrated that renal excretion of fluid, osmotically active substances and electrolytes could be reduced, using low gravitational exposures (+GZ). The degree and duration of water and electrolyte retention were different with respect to the experimental time. The major physiological mechanisms of the changes in fluid-electrolyte metabolism were: a decrease in the glomerular filtration rate and a change in water and ion transport in renal tubules.

Adult↗
PubMed1977

[Nervous apparatus of the 8th pair of cranial nerves after exposure to gravitation loading].

Neural apparatus of epineurium, perineurium and endoneurium of the cat vestibulocochlear nerve was studied by methods of Rasskazova, Bielshowsky--Gross, Kampos, Kuprianov, Gomori, Falck in modification of Chilingarian, Koelle--Gomori, Falck--Hillarp--Govyrin. A single gravitation loading effect was stated to produce reactive, and sometimes destructive changes in the sensitive nervous structures of the intraorganic apparatus of the neural sheaths. The greatest and earliest changes (the first day) were noted in the neural apparatus of epineurium of the vestibulocochlear nerve, the least and latest (the third day) -- in endoneurium.

Adaptation, Physiological↗