OBJECTIVES: We aimed to study the role of vestibular input on spatial memory performance in mice that had undergone bilateral surgical labyrinthectomy, semicircular canal (SCC) occlusion and 4G hypergravity exposure. METHODS: Twelve to 16 weeks old ICR mice (n=30) were used for the experiment. The experimental group divided into 3 groups. One group had undergone bilateral chemical labyrinthectomy, and the other group had performed SCC occlusion surgery, and the last group was exposed to 4G hypergravity for 2 weeks. The movement of mice was recorded using camera in Y maze which had 3 radial arms (35 cm long, 7 cm high, 10 cm wide). We counted the number of visiting arms and analyzed the information of arm selection using program we developed before and after procedure. RESULTS: The bilateral labyrinthectomy group which semicircular canal and otolithic function was impaired showed low behavioral performance and spacial memory. The semicircular canal occlusion with CO₂ laser group which only semicircular canal function was impaired showed no difference in performance activity and spatial memory. However the hypergravity exposure group in which only otolithic function impaired showed spatial memory function was affected but the behavioral performance was spared. The impairment of spatial memory recovered after a few days after exposure in hypergravity group. CONCLUSIONS: This spatial memory function was affected by bilateral vestibular loss. Space-related information processing seems to be determined by otolithic organ information rather than semicircular canals. Due to otolithic function impairment, spatial learning was impaired after exposure to gravity changes in animals and this impaired performance was compensated after normal gravity exposure.
Animals ; Arm ; Automatic Data Processing ; Gravitation ; Hypergravity ; Memory ; Mice ; Mice, Inbred ICR ; Otolithic Membrane ; Semicircular Canals ; Spatial Learning ; Spatial Memory

Rotating wall vessels (RWVS), an ingenious apparatus for three-dimensional suspension culture, is widely used to build a simulated microgravity-effect on cell. Independent researchers have proposed hypotheses to illustrate why RWVS can simulate certain aspects of microgravity. Many of the hypotheses stated that the culture condition in RWVS is determined by the cellular mechanical environment which is a result of low fluid shear and microcarrier's motion. The microcarrier's motions consist of primary and secondary motions. In the light of the analysis of forces loaded by the microcarriers, some conclusions are drawn from the data on microcarriers' primary and secondary motions about which many simulations and observations have already been conducted.
Cell Culture Techniques ; instrumentation ; methods ; Gravitation ; Models, Theoretical ; Motion ; Rotation ; Stress, Mechanical ; Weightlessness Simulation

Although it is clear that changes of gravity can alter dramatically the functions and structures of cells, little is known about how living cells sense these signals and convert them into a biochemical response. Recent studies estimated that the changes of gravity might influence the single cell directly and indirectly. So far, the molecular mechanism of gravisensing remains unknown, however, according to a great deal of researches focusing on this point, several pathways could be considered: (1) Pre-stress perception pathway; (2) Cytoskeleton-perception pathway; (3) Stress-sensitive ion channel pathway; (4) Indirect effects of gravitational change.
Cell Physiological Phenomena ; Cytoskeleton ; physiology ; Gravitation ; Gravity Sensing ; physiology ; Signal Transduction ; Space Flight ; Weightlessness

BACKGROUND: Current studies have focused mainly on the push-pull effect (PPE), the reduction of +Gz tolerance when hypergravity (>+1 Gz) preceded by hypogravity (<+1 Gz). However, the reduced G tolerance could be induced by any G-transition. The frequency and extent of maneuvers to cause G-transition effect (GTEM) have not been studied previously in fighter aircraft. METHODS: 26 HUD (head-up display) videotapes from F-16 aerial combat training missions were reviewed for the presence of GTEM. The frequency and magnitude of the +Gz profiles were analyzed. RESULTS: GTEMs were found in 34 (29.6%) of 115 engagements reviewed. PPEMs (maneuvers found to cause push-pull effect) and rPPEMs (maneuvers found to cause reversed PPE) were found in 7.8%, 11.3% respectively. Combined maneuver that rPPEM followed by PPEM consecutively was found in 10.4% of engagements. There was no difference the frequency of GTEMs between BFM and ACM engagements (28.8% vs. 30.9%). CONCLUSION: GTEMs including PPEMs and rPPEMs are present in aerial combat training missions of F-16 aircraft and represent a significant source for accidents. These findings support the necessity of continued research into the physiologic response to GTE.
Aircraft* ; Humans ; Hypergravity ; Hypogravity ; Missions and Missionaries* ; Videotape Recording

Altered environmental gravity, including both hypo- and hypergravity, may result in space adaptation syndrome. To explore the characteristics of this adaptive plasticity, the expression of immediate early gene c-fos mRNA in the vestibular related tissues following an exposure to hypergravity stimulus was determined in rats. The animals were subjected to a force of 2 g (twice earth's gravity) for 1, 3, or 12 h, and were examined poststimulus at 0, 2, 6, 12, and 24 h. RT-PCR (reverse transcription polymerase chain reaction) and real-time quantitative RT-PCR were adopted to analyze temporal changes in the expression of c-fos mRNA. The hypergravity stimulus increased the expression of c-fos mRNA in the vestibular ganglion, medial vestibular nucleus, inferior vestibular nucleus, hippocampus, cerebellum, and cortex. The peak expression occurred at 0 h poststimulation in animals stimulated with hypergravity for 1 h, and at 6 h poststimulus in those stimulated for 3 h. In contrast, those stimulated for 12 h exhibited dual peaks at 0 and 12 h poststimulus. Bilateral labyrinthectomy markedly attenuated the degree of c-fos mRNA expression. Glutamate receptor antagonist also dramatically attenuated the degree of c-fos mRNA expression. These results indicate that expression of c-fos mRNA in response to hypergravity occurs in the vestibular related tissues of the central nervous system, in which peripheral vestibular receptors and glutamate receptors play an important role. The temporal pattern of c-fos mRNA expression depended on the duration of the hypergravity stimulus.
Animals ; Central Nervous System ; Cerebellum ; Ganglion Cysts ; Gravitation ; Hippocampus ; Hypergravity* ; Plastics ; Rats* ; Receptors, Glutamate ; RNA, Messenger* ; Space Motion Sickness ; Vestibular Nuclei

In the unusual manifestation of right upper lobe collapse confusing with mediastinal or parenchymal mass, both alteration of the pulmonary vessels and shifting pattern of the collapsed lobe to the periphery on supine positionare the key to the diagnosis of it rather than mediastinal or parenchymal mass. The mechanisms of these unusual manifestation s are obscure, however lobar torsion and gravity factor are considered to be a main process. Authors have experienced 2 cases of unusual manifestations of right upper lobe collapse due to bronchogenic carcinomaduring resent 2 years in Kyung Hee University hospital, and prsent radiologic findings.
Carcinoma, Bronchogenic ; Diagnosis ; Gravitation

BACKGROUND AND OBJECTIVES: Altered environmental gravity, including both hypo- and hypergravity, may result in space adaptation syndrome. To explore the characteristics of this adaptive plasticity, the expression of immediate early gene c-fos mRNA in the vestibular system following an exposure to hypergravity stimulus was determined in rats. MATERIALS AND METHOD: The animals were subjected to 2 G force (two-fold earth's gravity) stimulus for 3 hours, and were examined at post-stimulus hours 0, 2, 6, 12, and 24. Real time reverse transcription-polymerase chain reaction (RT-PCR) was adopted to analyze temporal changes in the expression of c-fos mRNA. RESULTS: The hypergravity stimulation produced the expression of c-fos mRNA in the vestibular ganglion, medial vestibular nucleus, inferior vestibular nucleus, hippocampus, vestibulocerebellum, and vestibular cortex. The peak expression occurred at hour 6 in the animals hypergravity-stimulated for 3 hours. Bilateral labyrinthectomy significantly attenuated the degree of up-regulation in c-fos mRNA expression. MK-801, an NMDA receptor antagonist, also significantly attenuated the degree of up-regulation in c-fos mRNA expression. CONCLUSION: These results indicate that the adaptive neuroplasticity in response to an altered gravity occurs in the vestibular-related organs in the central nervous system, in which peripheral vestibular receptors and NMDA receptors play an important role.
Animals ; Central Nervous System ; Dizocilpine Maleate ; Ganglion Cysts ; Genes, fos ; Gravitation ; Hippocampus ; Hypergravity* ; N-Methylaspartate ; Neuronal Plasticity* ; Plastics ; Rats ; Receptors, N-Methyl-D-Aspartate ; RNA, Messenger ; Space Motion Sickness ; Up-Regulation ; Vestibular Nuclei

Colorectal endoscopic submucosal dissection (ESD) still remains a technically difficult procedure. The maintenance of tissue tension and good submucosal exposure during dissection is one of the most important factors for an effective and safe dissection. Although various traction methods have been developed, traction by gravity is one of the most useful method for colorectal ESD. Traction using adjunctive devices can thus be reserved for extremely difficult cases or for endoscopists in their learning periods for colorectal ESD.
Colorectal Neoplasms ; Gravitation ; Learning ; Traction

It has been shown that the minimum gravity exposure requirements vary greatly among different physiological systems. A preliminary comparison between two extremes, vessels vs. bones, shows that not only the mechanostat at the tissue level differs greatly, but also the bone loss during weightlessness may also involve calcium deposition-resorption changes. It seems that the surprising efficacy of intermittent artificial gravity (IAG) is due to the vascular tissues possessing a strong resilience or "memory" function toward restoring their original pre-stress and tensegrity state at the 1 G environment. It appears that the bone tissue is related to a more complex tensegrity paradigm involving both osteoblasts and osteoclasts, and a longer half time for calcium deposition-absorption. Cell-level models (CellML) for calcium dynamics is currently available. We hope that the Physiome Project can use this modeling framework to help interpret the resistance of bones to IAG and to evaluate whether the "intermittent" or "continuous" AG scheme should be adopted eventually for future exploration-class spaceflight.
Animals ; Bone and Bones ; Calcium ; Gravity, Altered ; Osteoblasts ; Osteoclasts ; Rats ; Weightlessness ; Weightlessness Simulation

A variety of technique of dynamic pharmacocavernosometry have been described to evaluate cavernous veno-occlusive function: however, there is no uniquely reliable and standard method so far After intracavernous (IC) injection of 45 mg papaverine and 2.5 mg phenblamine, we performed gravity cavernosometry(GC) and pump cavernosometry(PC), ie, measurement of saline infusion rate needed to obtain and to maintain an erection and measurement of pressure decay for 30 seconds and pressure drop time to 75 mmHg when pump was turned off at 150 mmHg IC pressure. Final diagnosis of venous leakage was made by cavernosoeraphy done at 90 mmHg IC pressure. The parametric values measured by each method to diagnose venous leakage and correlation among these methods were analyzed. The etiology of impotence in 45 patients studied was psychogenic in 8, venogenic in 21, combined arteriogenic and venogenic in 16. The measurement of induction flow rate was less reliable(p<0.05) for the diagnosis of venous leak than the other methods of PC and GC (p<0.01). The standard deviations of the induction and maintenance flow rate and pressure drop time were similar to or even higher than mean values. There was correlation among all these methods. Therefore, GC and PC, particularly measurement of the intracorporeal pressure decay are believed to be valuable methods for diagnosis of the corporal-venous leakage.
Diagnosis ; Erectile Dysfunction ; Gravitation ; Humans ; Male ; Papaverine