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At least 307 records · Page 17Linked to original sources
PubMed1997

[Observation of EGG parameters during -6 degrees head-down bedrest for 21 days].

Electrogastography (EGG) was recorded in 15 healthy volunteers before and after meal during 21 days head down tilt -6 degrees bed rest. The results showed that nausea, distension and pain in the abdomen and loss of appetite appeared at the beginning of bed rest and body weight decreased significantly (P < 0. 01) after bed rest; Low frequency (Bradygastria) proportion of EGG (<2.4cpm) increased apparently after 8 days of bedrest, and there was significant difference (P <0.05) between preprandial and postprandial bradygastria. The dynamic parameters of bradygastria declined significantly and the rhythm of bradygastria increased with duration of bedrest. It indicates that simulated weightlessness may cause decrease of gastric rhythm and gastric motility.

Aerospace Medicine↗
PubMed1997

[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↗
PubMed1995

Clinorotation inhibits chondrogenesis in micromass cultures of embryonic mouse limb cells.

Studies of the response of mammalian chondrocytes to gravitational changes in vivo, in organ culture, and in cell culture show that chondrogenesis is reduced in microgravity or by unloading, and increased by low levels of excess g. To investigate the cellular responses to microgravity using a ground based model, micromass cultures were exposed to simulated weightlessness on two clinostats. For rotation on the large clinostat, cultures were set up in Rose chambers, and cells were videotaped and photographed at several time periods after rotation began. For the smaller clinostat, cultures were set up in T-flasks, and two axes of rotation for clinostated cultures were used. Stationary controls [+1 g, -1 g (upside-down), and sideways] as well as rotation controls were employed. Rotation rate was 30 rpm for both clinostatted cultures and rotation controls. Chondrocyte differentiation was assessed by cartilage specific alcian blue staining. Significantly fewer alcian blue stained nodules were present in clinostatted cultures than in stationary controls or rotation controls. Nodules that did not stain with alcian blue, probably due to unsulfated matrix were present in all cultures. The number of nodules in sideways controls was greater than in any other culture (108% of +1 g controls), probably due to ongoing stimulus of the cell via cytoskeletal components. The results show that chondrocytes in culture respond to changes in the gravity vector in a predictable manner, and that carefully controlled clinostat studies can be useful adjuncts to and predictors for spaceflight experiments.

Animals↗
PubMed1989

Preparatory studies for the use of plant protoplasts in space research.

An experiment using plant protoplasts has been accepted for the IML-1 mission to be flown on a space shuttle in 1991. Preparatory experiments include studies of cell wall formation, cell division, the effect of simulated weightlessness using fast and slow rotating clinostats, and the development and testing of hardware for the IML-1 mission. After 24 h at 25 degrees C, protoplasts isolated from hypocotyls or leaves of rapeseed seedlings, or from carrot suspension cells, show 60, 20 and 15% cell wall formation, respectively. The time course of formation of the cell wall and cell division could be delayed by treatment at low temperatures or immobilization in alginate or agarose. This aspect is of importance in connection with problems of late access to the space shuttle before launch. At 4 degrees C only 18% of the rapeseed hypocotyl protoplasts had formed cell walls after 24 h. Protoplasts immobilised in agarose or alginate gradually regain their cell division capacity and after 72 h the frequencies are 51 and 26%, respectively, compared to non-immobilised control protoplasts. A significant decrease in cell division activity is observed after rotation for 6 h on the slow clinostat. A similar effect is not observed on the fast clinostat. Protoplasts, cultured in the specially designed plant chamber for up to 14 days established cell aggregates which have further developed into plants.

Alginates↗
PubMed1998

Temporal and spatial features of slow positive potential related to visual selective response during head-down-tilt.

The temporal and spatial features of visual ERP changes during 2 hour HDT (-10 degrees) were compared with that during HUT (+20 degrees) in 15 normal subjects. The stimuli consisted of two color LED flashes appeared randomly in left (LVF) or right (RVF) visual field with the same probability. The subjects were asked to make switch response to target signals (T) differentially: switching to left for T in LVF and to right for T in RVF, and making no response to non-target signals (N). Five sets of tests were made during HUT and HDT. ERPs were obtained from 9 locations on the scalp. Mean amplitude of the ERPs in the period 0.30-0.55 s were taken as the amplitude of slow positive potential (P400). The results obtained were: (1) The mean amplitude of P400 decreased during HDT which was more significant at the 2nd, 3rd and 5th set of tests; (2) spatially, the reduction of mean P400 amplitude during HDT was more significant for signals from RVF and were more significant at posterior and central brain regions than those from frontal locations. These data provide further evidence showing that the higher brain function was affected by the simulated weightlessness and that this effect was not only transient but also with interesting spatial characteristics.

Adult↗
PubMed1998

[Effects of extremity cuffs against physiological changes induced by head-down bedrest].

-6 degrees head down bedrest (HDBR) 10d was used to simulate weightlessness. 12 volunteers were randomed into control group and cuffs group, with 6 in each group. Inflated cuffs on the upper part of thighs and arms were performed 12 h/d in cuffs group during bedrest. No countermeasures were applied in the control group. During head up tilt (HUT) +75 degrees 20 min orthostatic tolerance test after HDBR, 5 in control group became presyncopal, while only one in cuffs group. The study indicates that the use of inflated cuffs provides a protective effect against the cardiovascular deconditioning after bedrest.

Adolescent↗
PubMed1991

Clinostatic rotation decreases crossover frequencies in the fungus Sordaria macrospora Auersw.

Two-factor crosses between the non-allelic spore colour mutants r2 and lu of the fungus Sordaria macrospora were used to investigate the effect of clinostatic rotation (= simulated weightlessness) on crossover frequencies. The experiment was carried out with different rotary directions at a rotary rate of 4 rpm. Second-division segregations of the gene lu, which result from crossover between the gene locus and centromere, are significantly smaller in the clinostat experiments than in the static controls. No differences were found between the two rotary directions. A similar influence of clinostatic rotation was not observed for the gene r2 which in contrast to the lu locus is located very close to the centromere. The suitability of this approach for the investigation of the effect of space flight conditions on cytogenetic processes is pointed out.

Chromosome Mapping↗
PubMed1999

[Variation of several volume regulating hormones during 21 d - 6 degrees head-down bed rest].

UNLABELLED: Objective To investigate variations of plasma renin activity, a prostaglandin I2 (PGI2) during 21 d -6 degrees head-down tilt (HDT) with and without lower body negative pressure (LBNP). METHOD: -6 degrees head-down tilt for 21 d were used to simulate weightlessness. 12 healthy male, aged 23.7 +/- 5.0, were equally and randomly divided into control group (CON) and LBNP group. The latter subjected to LBNP (-30 mm Hg, 1 h/d) in the last week of HDT. Samples of plasma were taken before HDT and on the 2nd, 4th, 11th and 22nd day during HDT. RESULT: Compare to control levels, Ald declined significantly on the 2nd (CON -30%, P < 0. 05; V. S. LBNP -38%, P < 0.01), and increased significantly on the 11th day (CON +30%, P < 0.05; LBNP +48%, P < 0.01). PRA reached peak value on the 4th day (P < 0.05), and declined to below the control level on the 22nd day. PGI2 increased constantly during HDT, and increased significantly on the 22nd day (CON P < 0.01), 11th, 22nd (LBNP P < 0.05). No apparent difference was found between groups after LBNP concerning PRA and Ald; and PGI2 didn't increase further in LBNP group. Conclusion HDT induced a timely increasing in PRA and Ald, constant increasing in PGI2.

Adaptation, Physiological↗
PubMed1999

[Protective effect of RenShen compound and DanHuang compound on muscle atrophy in suspended rats].

OBJECTIVE: To study the protective effect of RenShen compound and DanHuang compound on muscle atrophy caused by simulated weightlessness in rats. METHOD: Percentage and cross sectional area of fibers and ultrastructure of soleus (SOL) and gastrocnemius (GAS) were determined in 30 d tail suspended rats with or without administration of the medicine. RESULT: The percentage of type I fiber of SOL in RenShen (RS) group and DanHuang (DH) group increased by (13.5 +/- 0.96)% (P < 0.05) and (11.2 +/- 0.84)% (P < 0.05) respectively, and those of GAS showed only an increasing trend as compared with suspension control (SC). Cross sectional area of muscle fibers of SOL and GAS in both groups increased, especially in RS group (P < 0.05). The construction of SOL sarcomere in RS and DH groups was improved as compared with SC. CONCLUSION: RS and DH compounds can partially prevent muscle atrophy caused by tail suspension.

Animals↗
PubMed1999

LBNP-induced changes in plasma cGMP with and without head down tilt bed rest.

This investigation was conducted to test the following hypotheses: 1) If simulated orthostasis (LBNP) reduces plasma cGMP; 2) if simulated microgravity alters any such LBNP-induced effect; and 3) if simulated microgravity reduces resting plasma cGMP levels. In addition, we studied the time-course of thoracic impedance during, LBNP and asked if there is heart rate/blood pressure reduction after LBNP. During real and simulated spaceflight, blood is re-distributed throughout the vasculature along the body axis, vascular mechanoreceptor loads are altered, "excess" fluid is lost from the organism, and reflexly connected endocrine systems adapt with accompanying changes of hormone output. Altered steady-state plasma concentrations of volume sensitive hormones have been observed inflight as well as postflight. Hormones play a salient role in volume regulation but have barely been studied during microgravitational conditions in conjunction with lower body suction (LBNP). We used LBNP as an analogue to orthostatic stress since this model is useful to investigate, on quantitative grounds, hormone concentration changes as a function of cardiovascular stress in simulated weightless conditions. Earlier we reported consistently reduced plasma ANP and cGMP levels in a case study (14 mo spaceflight); transient hormonal changes after LBNP (as % of pre-LBNP values) were not different (p>0.05) from ground-control findings, and other hormone levels did not consistently deviate from ground control values. This is important since transmural central venous pressure which influences ANP output from the heart, and is elevated despite decreased CVP in parabolic flight, might be downregulated on a long-term basis. TCVP has not yet been measured inflight.

Bed Rest↗
PubMed1998

[Effect of tail suspension on mitochondrial Ca2+ and Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle].

Changes of mitochondrial Ca2+, mitochondrial Mg2+ and parameters of electron microscopic morphometry in rats' skeletal muscle after 15 or 30 d tail suspension were observed. The results showed that mitochondrial Ca2+ [correction of Ma2+] mitochondrial Mg2+ increased and morphometry of mitochondrial in skeletal muscle showed that volume density (Vv), surface density (Sv), numerical density (Nv) increased. Mean volume (V) decreased. Specific surface increased in soleus muscle, while that parameter remain unchanged in gastrocnemus musles. It suggests that these changes may be denoted to the decrease of muscular contractive function in simulated weightlessness.

Animals↗
PubMed2001

[Counteraction effect of intermittent -Gx on changes of responsiveness of basilar artery in tail-suspended rats].

OBJECTIVE: To investigate counteracting effects of intermittent -Gx exposure on changes of responsiveness of basilar artery in tall-suspended rats. METHOD: Rats tail-suspended for 3 wk were daily subjected to 1 h 1.5 G or 2.6 G centrifugation, simulating -Gx exposure of various G values. Responses of perfused isolated basilar arterial rings to KCl was examined. RESULT: Maximal isometric contractile response to KCl were significantly enhanced in arterial rings isolated from 3 wk tail-suspended rats as compared with that from simultaneous control rats (P < 0. 05). However, maximal isometric contractile responses to KCl of arterial rings isolated from 3 wk tail-suspended plus daily -Gx exposure rats were no difference as compared with that from simultaneous control rats, and were significantly decreased (P < 0.05) as compared with that from 3 wk tail-suspended rats. CONCLUSION: Daily intermittent -Gx exposure as a countermeasure to prevent the effects of simulated weightless on changes in responsiveness of basilar artery from tail-suspended rats was valid.

Animals↗
PubMed2001

[Changes of human recombination bone morphogenetic protein-2 in bone and marrow in tail suspended rats].

OBJECTIVE: To study human recombination bone morphogenetic protein-2 (rhBMP-2) change in bone and marrow under simulated weightlessness. METHOD: 5 SD rats were tail suspended for 14, 28 d with another 5 freely active rats as control. Histological samples were in situ hybridized. RESULT: rhBMP-2 expression of bone and marrow were lower in tail suspended rats than control levels (P < 0.05). rhBMP-2 expression tail suspended rats in 14 day were higher than that in 28 day suspended group (P < 0.05). CONCLUSION: rhBMP-2 levels in rats bone and marrow were lower after tail suspension.

Animals↗
PubMed1999

[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↗
PubMed2001

[Effect of head-down bed rest on human EEG].

Objective. To study the influences of short-term simulated weightlessness on human EEG. Method. EEG of 12 male subjects (aged 18-22) was recorded, pre-HDBR (-6 degrees head down bed rest), mid-HDBR (3rd, 4th, 6th day) and post-HDBR (3rd day). Then these EEG recordings were analyzed by power spectral analysis. Result. During HDBR, peak frequency of EEG gradually slowed down (6th day, P<0.05). Alpha-band activities were enhanced (alpha1: P<0.001. Alpha2: 3rd and 6th day, P<0.05; 4th day, P<0.001) and reached maximum on the 4th day. Alpha1/alpha2 ascended (6th day, C3 and C4: p<0.02; F4, P4, T3, T4, T5: P<0.05). Theta-band activities enhanced (P<0.001), and reached maximum on the 3rd day at frontal regions, on the 4th day at parieto-occipital regions. Theta/alpha ascended obviously (6th day, P3, O1: P<0.05). Meanwhile, beta1, activities also enhanced (P<0.001), and reached maximum on the 3rd day at frontal regions. After HDBR, the index that recovered to the pre-HDBR level first was EEG peak frequency. Conclusion. HDBR caused obvious changes of EEG power spectrum characteristic. There exists a potential influence on brain function.

Adolescent↗
PubMed2001

[Protective effects of Chinese herb-compound on cellular immunological function (correction of funcion) in tail-suspended rats].

Objective. To observe the protective effects of two kinds of Chinese herb-compounds (Dan-huang-ci compound and Shen-chuan-shu compound) on cellular immunology in tail-suspended rats. Method. The rats were divided into: 1) normal control group; 2) tail-suspended group; 3) tail-suspended + Dan-huang-ci compound; and 4) tail-suspended + Shen-chuan-shu compound. Ability of lymphocyte proliferation and production of IL-2 in rats in the four groups were compared after 21 d. Result. The immunological function of tail-suspended control group decreased significantly as compared with normal control group. Shen-chuan-shu compound could improve immunological function of tail-suspended rats obviously. Conclusion. Shen-chuan-shu compound could enhance cellular immunological function in rats under simulated weightlessness.

Animals↗
PubMed2000

[Effects of tail suspension on learning and memory function of mice].

Objective. To study the effects of simulated weightlessness on learning and memory capability of the brain. Method. Accuracy fraction, error frequency and pass rate were observed among control, restrained control, tail suspended (TS) control, restrained, and tail suspended mice in square water maze tests. And latent period and error time were observed in control and 30 degrees tail suspension mice in step down test. Result. The indices did not change significantly during learning period. Accuracy fraction of tail suspended group was reduced significantly in the tests as compared with pretest values. In step down test, latent period and error time showed no difference between TS 5 h and 2 d in untrained mice, but shortened evidently after TS 2 d and prolonged after TS 7 d in trained mice, which suggested the degradation of learning and memory ability after TS 5 h and 2 d respectively. Conclusion. Acute tail suspension depressed brain's learning ability and quality, while tail suspension of 7 d and 12 d impaired the spatial memory in mice.

Animals↗
PubMed2000

[Changes of femur minerals and serum BGP in hindlimb unloaded rats during convalescence].

Objective. To observe bone mass changes during convalescence after simulated weightlessness. Method. 7-week-old rats were tail-suspended for 21 d then reloaded for 7 d and 21 d to recover, and measured serum BGP. Result. Tail suspension of rats for 21 d caused significant decrease of serum BGP and phosphorus as well as femur minerals. Serum BGP and femur minerals were still lower than control levels, but serum contents of calcium, phosphorus and magnesium increased significantly after reloading for 7 d. Femur minerals and serum BGP, calcium, phosphorus and magnesium returned to control levels after reloading for 21 d. Conclusion. The deficit in femur mineral induced by hindlimb unloading in rats can be restored by return to normal weight bearing, BGP can be used to monitor the case of its recovery.

Animals↗