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At least 163 records · Page 9Linked to original sources

[Human tolerance to Coriolis acceleration during exertion of different muscle groups].

The effect of an arbitrary loading of different muscle groups (shoulder, back, legs) and motor acts on the tolerance to Coriolis accelerations was investigated in 140 experiments in which 40 test subjects participated. The accelerations were cumulated and simulated by the Bryanov scheme. Muscle tension was accompanied by a less expressed vestibulo-vegetative reaction and shortening of the recovery period after the development of motion sickness symptoms. The greatest changes were observed during the performance of complex motor acts and tension of shoulder muscles. Possible mechanisms of these effects are discussed.

Adult↗

[EGG and nausea under vestibular stimulus].

81 pilots were exposed to vestibular stimulus with Coriolis acceleration. They were divided into two groups, the first group consisted of 38 pilots with nausea symptoms, the second group 43 pilots without nausea symptom. Dominant frequency instability coefficient (DFIC), dominant power instability coefficient (DPIC), Tachygastria, Bradygastria and normal slow wave components (NSW) of the electrogastrogram (EGG) were analyzed. The results showed that Bradygastria and NSW of EGG were related to nausea symptom of pilots under Coriolis stimulation.

Aerospace Medicine↗

Biomedical aspects of artificial gravity.

Artificial gravity (AG) is the basic challenge for space biology and medicine. The importance of this problem is associated with the fact that duration of the space missions will become progressively longer, but the presently available countermeasures do not provide reason enough to predict the human health safety during space missions of any duration. The creation of AG could be an efficient method for removing the negative effects of microgravity. Two principle methods of generating AG, rotation of space system (SS) and building of short arm centrifuge (SAC), have been proposed. The purpose of the present work is to review the biomedical aspects of AG in the context of its use in long-term space missions.

Aerospace Medicine↗

[Observation of electronystagmogram in pilots under vestibular stimulation].

The relationship between electronystagmogram(ENG) and intensity of vestibular stimulation was observed in 62 pilots. 31 pilots received low intensity vestibular stimulation and the other 31 pilots received higher intensity vestibular stimulation. Electronystagmogram were recorded and analysed. The results showed that there was no relationship between the ENG parameters and stimulation intensity, but both slow phase and fast phase velocities and amplitudes were lower under Coriolis acceleration stimulus, while all of them were higher under angular acceleration and angular stimulations. It was also found that the fast phase amplitude of ENG was related to motion sickness symptoms of the subjects.

Acceleration↗

Effects of angular speed in responses of Paramecium tetraurelia to hypergravity.

The paper shows the results of investigations carried out in a single cell organism. Paramecium tetraurelia exposed to different gravitational levels. Hypergravity resulted in a decrease in cell growth rate. The responses depend on g level and angular speed of the centrifuge; furthermore they depend also on small short fluctuations in g levels, delta g, due to the swimming of the cells inside the culture tubes. Delta g depends on angular speed and size of the holding device. The inhibitory effect of hypergravity, for the same angular speed, increases with respect of the diameter of the culture tubes.

Animals↗

Is there a role for nonsedating antihistamines in motion sickness? Fallout from space research may soon benefit your patients.

The rotating chair test, a novel research technique for simulating motion sickness, is used to study the effect of nonsedating oral antihistamines in preventing or forestalling motion sickness. After receiving terfenadine, astemizole, doxepin, or placebo, four groups of male volunteers were rotated at accelerating speed, and they made head movements out of the axis of rotation until they perceived that vomiting would occur if additional head movements were made. Those pretreated with doxepin or terfenadine experienced a statistically significant prophylactic effect, as measured by increased tolerance to Coriolis stimulation. This suggests that selective peripheral H1 antihistamine action may protect against motion sickness.

Aerospace Medicine↗

[Changes of plasma endocrine hormone in pilots under Coriolis acceleration].

Plasma endocrine hormones were studied in both 24 motion sickness (orthostatic intolerance) and healthy pilots. Coriolis acceleration of 3.75, 5.00 and 6.25 pi 2 cm/s2 were given with intervals of 3-4 min AT-II, insulin, cortisol, Aldosterone and gastrin were determined by radioimmunoassay. It was found that aldosterone, AT-II, gastrin increased with increase of coriolis acceleration in all pilots. (P < 0.05), but cortisol and insulin only increased in healthy pilots (P < 0.05). It suggests excitation of the autonomic nervous system might be insufficient in orthostatic intolerant pilots and that determination of endocrine hormones may be useful in the evaluation of autonomic nervous activities.

Acceleration↗

The menstrual cycle and susceptibility to coriolis-induced sickness.

Survey studies on motion sickness susceptibility suggest that females tend to report greater severity in illness and higher incidence of vomiting than males. Menstruation is said to be a contributing factor. A recent study suggested that females were least susceptible to seasickness during ovulation in a "round the world" yacht race. Sixteen subjects (18-36 years old) were exposed to Coriolis cross-coupling stimulation in the laboratory. They were tested once during permenstruation (Day 1-5), ovulation (Day 12-15) and premenstruation (Day 24-28), based on a normalized 28-day cycle, in a randomised design. Physiological measurements of motion sickness included forearm and calf cutaneous blood flow. Subjective evaluation of sickness symptoms was based on Graybiel's diagnostic criteria and Golding's rating method. Our results indicated that under controlled laboratory conditions, different phases of the menstrual cycle appear to have no influence on subjective symptoms of motion sickness or on cutaneous blood flow increase in the forearm and calf. The lack of commonality between the types and levels of hormones that are released during motion sickness and those that are involved in different menstrual phases appears to support our findings.

Adult↗

[Physiological evaluation of vestibular training load].

Objective. To evaluate the effects of vestibular training by observing the variations of the physiological indices. It is helpful in grasping the training load, setting down and implementing the training plan. Method. 10 healthy subjects received linear acceleration, continuous Coriolis acceleration and discontinuous Coriolis acceleration stimuli on different dates. The stimulus was stopped when there were slight autonomic nervous symptoms, ECG, EGG and BP were recorded before during and after the stimuli. Computerized Dynamic Posturography (correction of Postrograph) (CDP) was tested before and after experiment. Result. One subject finished the training of the three stimuli with only slight autonomic nervous symptoms. The CDP tests pre- and post-experiment indicated that for most subjects the contribution of vestibular function in maintaining dynamic posture equilibrium increased after the linear acceleration stimuli, but decreased after continuous Coriolis acceleration stimuli, and there was great individual difference after discontinuous Coriolis acceleration stimuli because the stimulation was relatively heavy. The equilibrium score in SOT2 decreased significantly after linear acceleration stimuli, and increased significantly after discontinuous Coriolis acceleration stimuli. Conclusion. The training methods we designed and used in this experiment are feasible, and the required training load can be reached. EGG, BP and the percentage of LF (low frequency) in ECG R-R power spectrum can reflect the subject's condition when the period stimuli stopped. It provided important reference in the determination of training stimulation load.

Acceleration↗

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↗

[Variations of EGG in subjects under vestibular stimulation].

Objective. To investigate the patterns of electrogastrogram [correction of electrogastrogragm] (EGG) before, during and after vestibular stimulation. Method. 25 subjects were stimulated by Coriolis acceleration and 28 by Coriolis [correction of corolis] stimulation. Result. Dysrythmia of EGG and increase of tachygastria were recorded in all subjects during the stimulation. The period dominant frequency (PDF) of EGG shifted from 2.40-3.70 cpm to 3.70-10.00 cpm during Coriolis stimulus in subjects with nausea. Conclusion. It suggests that PDF could be a parameter in reflecting the level of motion sickness.

Acceleration↗