Reaping rewards from space life sciences.
Explore the source record for details and available documents.
Aerospace Medicine↗
SEARCH · Search PubMed
Results for “Weightlessness Countermeasures”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[A study on the counteracting effect of hypoxia and Qigong on simulated weightlessness and orthostatic tolerance after bedrest].
-6 degrees head down bed rest (-6 degrees HDBR) 21d were used to simulate weightlessness. 15 healthy males, aged 19-22, were divided into 3 groups with 5 people in each group: control group (-6 degrees HDBR), hypoxia group (-6 degrees HDBR + Low Oxygen), Qigong group (-6 degrees HDBR + Qigong). The results showed that the reduction of weight, perimeter of shank, daily average cardic output, basal cardic output and the pulse pressure of the Qigong group were lower than those of the control group (P<0.05). The basal cardic output and the perimeter of shank of the Hypoxia group reduced significantly than those of the control group (P<0.05). However, the reduction of the other physiological functions of the Hypoxia group were not significantly lower than that of the control group (P>0.05). During HUT +75 degrees 20 min orthostatic tolerance test after HDBR, the parameters in the Hypoxia group were better than those in the other groups. The average standing time was also longer, and no presyncopal symptom occured.
Adaptation, Physiological↗
Effects of Chinese herb medicine on improving the circulation of rabbits under simulated weightlessness.
In order to find out the effects of Chinese herb medicine on improving the functional state of blood circulation under weightlessness (WL) or simulated weightlessness (SWL), five experiments (building the SWL animal model and determining the treatment based on the differentiation of symptoms and signs, selecting herb medicine, determining the dosage of Chinese herb medicine, pharmacological text and toxicological experiment of (DH) were accomplished. Two kinds of Chinese herb medicine(CQ and DH) having the effects of improving the circulatory conditions of rabbits in SWL were selected. SWL animal model, space blood stasis and mechanism and effects of Chinese herb medicine were discussed.
Animals↗
[Effects of octacosanol in food physiological parameters in tail-suspended rats].
The purposes of the experiment were to observe the physiological effects of octacosanol in food on tail-suspended rats and to investigate the possibility of using octacosanol in health food for astronauts. 24 male Wistar rats were randomly divided into free action control, tail-suspension and tail suspension plus octacosanol (TSO) groups. Octacosanol was emulsified into water by supersound and given to TSO rats with a dosage of 25 mg/kg wt d. The results showed that octacosanol elevated the weight of thymus, improved biomechanical properties of the femur and improved membrane fluidity of red blood cell. It suggests that octacosanol can counteract some effects of simulated weightlessness on rats. Therefore, octacosanol may be added to natural foods to benefit the health of cosmonauts.
Aerospace Medicine↗
Influence of bisphosphonates on calcium metabolism and bone tissue during simulation of the physiological effects of microgravity.
At present a significant experience has been gathered in experimental and clinical use of synthetic derivatives of bisphosphonic acid. Purpose of our study was to investigate the effects of bisphosphonates on calcium metabolism and bone tissue in humans and animals under the conditions simulating the physiological effects of microgravity. In a series of experiments with animals the effectiveness of various preparations and treatment plans was compared Action of 1-hydroxyethyliden-1, 1-bisphosphonic acid (EHBP, xydiphon) on calcium metabolism and bone tissue in human was the subject of experiments with long-term head-down tilt (HDT).
Animals↗
[Effect of extremely low frequency magnetic field on brain response to selective mental arithmetic under simulated weightlessness].
Objective. To study effects of extremely low frequency magnetic field (ELMF) on brain function state during weightlessness. Method. The brain event-related potentials (ERPs) during a selective mental arithmetic task were compared in 40 normal subjects (20-25 yrs) before and after ELMF (5 Hz) stimulation during simulated weightlessness (head down tilt -10 degrees, HDT). Result. The amplitude of slow positive potentials which were supposed to be related to the mental arithmetic activity decreased significantly especially in 100 min after HDT, but it did not decrease significantly after ELMF stimulation. Conclusion. ELMF stimulation may improve the brain function state during simulated weightlessness.
Adult↗
[Counteracting effect of Chinese herbs-compounds on "blood stasis" induced by bed rest].
Objective. To observe the improved effect of syndromes of blood stasis by taking Chinese medicine during bed-rest simulated weightlessness. Method. Ten subjects were randomly divided into two groups: Chinese medicine group and control group. Both of them were exposed to HDBR -6 degrees for a week. The Chinese medicine group took Chinese medicine during the bed rest, and the control group took sugar water. Result. Syndromes of blood stasis of Chinese medicine group had a significant relief. And some physiological parameters, such as blood pressure, pulse graph, and amount of urine, maintained the level of pre-bed rest. While the control group was more severe than the Chinese medicine group in syndromes of blood stasis. Conclusion. Chinese medicine can be a measure in preventing the effect of weightlessness.
Adolescent↗
[Counteracting effect of Chinese herbs on "insufficiency of spleen qi" induced by simulated weightlessness].
Objective. To observe the counteracting effect of a Chinese herb-compound on "insufficiency of spleen qi" induced by simulated weightlessness. Methods. Animal and human experiment were carried out to the Chinese herb-compound (Dangshen, Baizhu, Fuling etc). Result. This compound protected the tail suspended rats from atrophy of spleen, thymus, soleus and gastrocnemius muscles, prevented excessive decrease of body weight effectively; at the same time it relieved the symptoms of the subjects greatly. Conclusion. It demonstrated that the compound decreased the "insufficiency of spleen qi" of both animals and human subjects.
Aerospace Medicine↗
[Changes of cerebral blood flow during 21 d head-down tilt bed rest and the effect of lower body negative pressure during the last week].
Objective. To investigate the changes of cerebral blood flow (CBF) during 21 d head-down tilt (HDT) bed rest and the effect of lower body negative pressure (LBNP) in the last week. Method. Twelve healthy male subjects were randomly divided into control and LBNP groups, with 6 in each group. All of them were exposed to -6 degrees HDT for 21 d. The LBNP group received -4.0 kPa LBNP training 1 h/d in the last week of HDT while the control group did not. CBF and cerebral vascular resistance were measured by rheoencephalogram in pre-HDT, day 3, 10 and 21 of HDT. Result. In control group, left cerebral I quadrant area and inrush velocity decreased significantly during HDT, and left cerebral delta Gy wave crest height decreased significantly, whereas left cerebral resistance index increased significantly on day 3 and 21 of HDT as compared to those of pre-HDT. In LBNP group, left cerebral I quadrant area decreased significantly, and left cerebral delta Gy wave crest height and inrush velocity tended to decrease on day 3 and 21 of HDT, whereas left cerebral resistance index increased significantly during HDT as compared to those of pre-HDT. There were no significant differences between above indexes in control group and LBNP group. Conclusion. It is suggested that 21 d HDT may increase cerebral vascular resistance and decrease CBF, which can not be prevented by LBNP training in the last week of 21 d HDT.
Adult↗
[Effects of vitamin K on bone metabolism in tail-suspended rats].
Objective. To study the effects of vitamin K on bone metabolize in simulated weightlessness rats. Method. Male SD rats were divided into three groups (n = 9): the free active control (FAC), the tail-suspended control (SC), and the tail-suspended group treated with vitamin K (SVK) (50 mg/kg weight/d). The experiment lasted for 3 weeks. Bone biomechanical properties, bone mineral contents (BMC) and bone biochemical markers of bone metabolism were determined. Result. Compared with SC, total and bound bone gla protein (BGP) of serum, BMC of the femur and tibia, femoral mechanical properties, ALP activity of tibia all increased significantly; while NO content of femoral trunk decreased significantly. Conclusion. Vitamin K improved the bone metabolism and bone structure, decreased bone loss, increased bone biomechanical properties, decreased catagmatic fatalness. It proved that vitamin K prevented bone loss of simulated weightlessness rats.
Alkaline Phosphatase↗
[Daily 1 h standing can prevent depression of myocardial contractility in simulated weightless rats].
Objective. To observe and compare the effect of daily standing of rats for different durations in alleviating the depression of myocardial contractility induced by simulated weightlessness. Method. Fifty male Sprague-Dawley rats were randomly assigned to five groups: simultaneous control (CON), four-week tail-suspension (SUS), SUS plus daily 1 h standing (STD1), SUS plus daily 2 h standing (STD2) and SUS plus daily 4 h standing (STD4). Four weeks later, wet weights of the left soleus, testis and adrenal gland were measured, and the isometric contractile tension and its time parameters of isolated perfused papillary muscles from rats of various groups were examined. Result. Compared with CON, the wet weights of testis in different treatment groups decreased significantly (P<0.05). The wet weight of soleus in SUS decreased by 58.9% (P<0.01); but in STD1, STD2 and STD4, decreased by 38.5%, 24.0% and 11.0% (P<0.01, or P<0.05) respectively. The relative protections were 34.7%, 59.2% and 81.4% (P<0.01) respectively. In SUS group, developed tension (DT), peak rate of tension rise (+dT/dtmax) and peak rate of tension fall (-dT/dtmax) decreased by 32.2%, 29.2% and 30.7% (P<0.05), and time to peak rate of tension rise (TPP) and time to peak tension (TPT) prolonged by 21.2% and 11.0% (P<0.05), respectively. Whereas in STD1, STD2 and STD4, all the parameters reflecting myocardial contractility (like DT, + dT/dtmax, -dT/dtmax and TPP), did not show any significant change as compared with those of CON. However, being an exception, TPT still showed obvious prolongation (P<0.05) in STD1. Conclusion. Daily 1 h standing could prevent depression of myocardial contractility in rat induced by medium-term simulated weightlessness. However, with respect to prevention of atrophic changes in soleus muscle and testis, daily standing for 1 h, 2 h, or 4 h was only partially effective and even totally devoid of any effect, respectively.
Animals↗
Prevention of human deconditioning during prolonged immersion in water.
A 56-day immersion experiment in which two subjects participated was carried out. During the experiment the preventive effect of periodic acceleration combined with exercise and water-salt intake was assessed. Simulating an increased gravitational field, exposure to acceleration increased the static component of the load upon the musculo-skeletal system, increased the gradient of the blood hydrostatic pressure, activated mechanisms responsible for the venous return to the heart, stimulated systems regulating antidiuretic and antisodiumdiuretic reflexes. Involvement of these mechanisms restored haemodynamic parameters, fluid-electrolyte balance and blood coagulability. The prophylactic effect of acceleration was enhanced if combined with exercise and supplemented water-salt intake.
Acceleration↗
Cardiovascular studies during and following simulation and weightlessness.
Two major characteristics of space flight may be simulated to some degree by bed rest and by water immersion. These are inactivity and the lack of the hydrostatic stress on the systematic circulation. Studies prior to the advent of space flight led to the prediction of orthostatic intolerance, muscular weakness, and calcium loss. Prolonged space flight has heightened the interest in these simulations to provide information concerning the temporal cause of the "deconditioning" or disuse syndrome and the value of simulation for testing the effectiveness of remedial measures. This report will evaluate the extent to which the simulation appears valid. In its gross effects, orthostatic intolerance can be studied with respect to its temporal course, etiology and effectiveness of remedial measures. The intolerance develops more rapidly during water immersion with respect to cause as well as effect. The short term of immersion studies does not allow study of the secondary change in blood volume due to red cell mass changes, Remedial measures seem clearly defined in water immersion simulation and less clear in bed rest. Measures of venous pooling following water immersion appear different than those obtained following weightlessness. There also appear to be differences in the results of evaluation of protective devices and measures and in the time course of development and recovery of orthostatic intolerance. Correlates of the cardiovascular responses such as muscle tone, skeletal strength, and endocrine change (catecholamines, vasopressin and aldosterone) suggest a marked alteration in physiology during hypodynamic status. To date, work on exposure to increased G force has provided only extrapolated data concerning metabolic requirements.
Bed Rest↗
[Effects of lower body negative pressure in the first and last week during 21 d head-down bed rest on orthostatic tolerance and cardiac function].
OBJECTIVE: To investigate the changes of orthostatic tolerance and cardiac function during 21 d head-down tilt (HDT) bed rest and effect of lower body negative pressure (LBNP) in the first and the last weeks in humans. METHOD: Twelve healthy male volunteers were exposed to -6 degrees HDT bed rest for 21 d. Six subjects received -30 mmHg LBNP sessions for 1 h/d from the 1st to the 7th day and from the 15th to the 21st day of the HDT, and the other six who did not receive LBNP served as control. Orthostatic tolerance was assessed by means of standard tilt test. The cardiac pumping function and cardiac systolic function were measured before and during HDT. RESULT: Before HDT, all the subjects in the two groups completed the tilt tests. After 10 d and 21 d of HDT, all the subjects of the control group and one subject of the LBNP group could not complete the tilt test due to presyncopal or syncopal symptoms. The mean time of upright standing in the control group (15.0 +/- 3.2 min) was significantly shorter than those in the LBNP group (19.7 +/- 0.9 min). The stroke volume and cardiac output decreased significantly in the control group on days 3 and 10 of HDT, but remained unchanged throughout HDT in the LBNP group. A significant increase in preejection period (PEP)/left ventricular ejection time (LVET) was observed on days 3 and 14 of HDT in both groups. The PEP/LVET in the LBNP group was significantly lower than those in the control group on days 3 of HDT, while LVET in LBNP group was significantly higher than those in the control group on days 3, 7 and 14 of HDT. CONCLUSION: It is suggested that the brief daily LBNP sessions in the first and the last weeks were effective in preventing orthostatic intolerance and the reduction of cardiac pumping function and cardiac systole function induced by 21 d HDT bed rest.
Adult↗
Salt-loading and simulated microgravity on baroreflex responsiveness in rats.
Cardiovascular adaptations observed during exposure to microgravity results in impairment of baroreflex activity partially as a result of fluid and electrolyte shifts. The head-down tilt rat model mimics some of the physiological observations that have been made in astronauts. We examined the effects of salt-loading on baroreflex activity after 7 day simulated microgravity (30 degrees tail-suspension) and the subsequent 6 hr post-suspension in Sprague-Dawley (SD) rats, using low salt (0.3% NaCl) and high salt (8% NaCl) diets. In suspended animals on a low salt diet, the baroreflex response curve was shifted to the left, while the heart rate (HR) range and MAP50 values were reduced compared to their parallel tethered, non-suspended controls. For non-suspended animals, salt-loading shifted the curve to the right with a reduced HR range. In salt-loaded, suspended animals, the curve and its parameters resemble those of non-suspended animals on a low salt diet. In summary, these data have demonstrated that a short-term (seven days) simulated weightlessness may elicit cardiovascular deconditioning in rats after release from the simulation manifested as an altered responsiveness in baroreceptor-heart rate reflex and a lowered blood pressure while the rats are tethered and horizontal. Our results also suggest the counteracting effect of salt loading on cardiovascular deconditioning.
Animals↗
Locomotion in simulated microgravity: gravity replacement loads.
BACKGROUND: When an astronaut walks or runs on a treadmill in microgravity, a subject load device (SLD) is used to return him or her back to the treadmill belt. The gravity replacement load (GRL) in the SLD is transferred, via a harness, to the pelvis and/or the shoulders. This research compared comfort and ground reaction forces during treadmill running in a microgravity locomotion simulator at GRLs of 60%, 80%, and 100% of body weight (BW). Two harness designs (shoulder springs only (SSO) and waist and shoulder springs (WSS)) were used. HYPOTHESES: 1) The 100% BW gravity replacement load conditions would be comfortably tolerated and would result in larger ground reaction forces and loading rates than the lower load conditions, and 2) the WSS harness would be more comfortable than the SSO harness. METHODS: Using the Penn State Zero Gravity Locomotion Simulator (ZLS), 8 subjects ran at 2.0 m x s(-1) (4.5 mph) for 3 min at each GRL setting in each harness. Subjective ratings of harness comfort, ground reaction forces, and GRL data were collected during the final minute of exercise. RESULTS: The 100% BW loading conditions were comfortably tolerated (2.3 on a scale of 0-10), although discomfort increased as the GRL increased. There were no overall differences in perceived comfort between the two harnesses. The loading rates (27.1, 33.8, 39.1 BW x s(-1)) and the magnitudes of the first (1.0, 1.4, 1.6 BW) and second (1.3, 1.7, 1.9 BW) peaks of the ground reaction force increased with increasing levels (60, 80, 100% BW respectively) of GRL. CONCLUSIONS: Subjects were able to tolerate a GRL of 100% BW well. The magnitude of the ground reaction force peaks and the loading rate is directly related to the magnitude of the GRL.
Adult↗
Changes in urinary excretion of deoxypyridinoline in tail-suspended rats: effects of a bisphosphonate, YH529.
Urinary excretion of deoxypyridinoline (D-Pyr) has been shown to be a useful marker for bone resorption. In this study, we investigated whether D-Pyr could be used to monitor the changes in bone resorption of the hind limb induced by tail-suspension. Male Wistar rats 5-weeks old were tail-suspended in a metabolic cage to unload the hind limbs. The control rats were not suspended. YH529 (YH), an inhibitor of bone resorption, or a vehicle (phosphate buffered saline=PBS) was administered daily starting 3 days before the commencement of tail-suspension. In the non-suspended rats receiving PBS, urinary excretion of D-Pyr did not show any significant change during the one-week experimental period. In the non-suspended rats receiving YH, D-Pyr excretion significantly decreased on day 5 and 7 when compared with that observed on day 0, in accordance with the systemic inhibition of bone resorption by YH. In the tail-suspended rats receiving PBS, D-Pyr excretion showed a tendency to increase on day 1, which is in agreement with our previous report that tail-suspension causes an early (on day 1 of suspension) and transient increase in bone-resorption of the hind limbs. In the tail-suspended rats treated with YH, the increase in D-Pyr excretion on day 1 was not observed, and a significantly lower excretion was noted from day 3 to 7 during the tail-suspension. It was suggested that D-Pyr excretion might reflect the transient increase in hind limb bone resorption induced by tail-suspension. As observed in-YH treated rats, D-Pyr excretion could serve as a good marker for the inhibition of systemic bone resorption.
Amino Acids↗
[Effects of simulated microgravity on cardiovascular function and counter effect of lower body negative pressure].
Studies on effect of simulated microgravity on cardiovascular function and counter effect of lower body negative pressure (LBNP) in recent years were summarized. The mechanism of simulated microgravity induced orthostatic intolerance may involve the reduction of cardiovascular function and cerebral blood flow, and endocrine changes. The significance of mathematical model in the study of mechanism of microgravity induced orthostatic intolerance was also discussed. The counter effect of LBNP was emphasized.
Bed Rest↗