Although influence of magnetic field on live organisms has been studied for many decades, many questions, including process of polysaccharide deposition in plant cell, remain open. The study of the influence of weak, combined magnetic field (CMF), which was adjusted to the cyclotron frequency of Mg2+, Ca2+ and K+ ions, on the cell wall regeneration by plant protoplasts was carried out using the apparatus with sinusoidal frequency of 32 Hz inside a g-metal shield. Protoplasts were isolated from: 1) soybean (Glycine max) and Nicotiana tabacum callus and 2) Nicotiana plumbaginifolia and N. sylvestris leaf mesophyll. The next combinations of parents protoplasts have been realized for the fusion: N. sylvestris + N. sylvestris; N. plumbaginifolia + N. tabacum and N. plumbaginifolia + G. max. Petri dishes with control samples were situated near the apparatus with CMF. For light microscope observation, the native cells of callus and leaf mesophyll, and the protoplasts that had been allowed to regenerate cell walls for 3-6 h were fixed in 1 % paraformaldehyde, washed and stained with 0.001% Calcofluor White M2R, and then studied under laser confocal microscope (LSM5 Pascal). It is revealed that the relative content of cellulose in cell walls of callus and mesophyll cells was more than that in regenerated walls of protoplasts. It is established that the rate of cell wall regeneration is dependent on the combination of parents’ pairs as in the control, so in CMF. The regeneration of cell wall by protoplasts isolated with callus is occurred faster than by protoplasts isolated with mesophyll. The action of CMF with the cyclotron frequency for Mg2+ was more effective for the regeneration of cell wall in comparison with the control samples. The number of experimental protoplasts (in CMF) with regenerated cell wall was in two times more than in the control. It is possible; this phenomenon was consequence of the activation of cellulose-synthase under influence of CMP, which was adjusted to the cyclotron frequency of Mg2+.

Objective Exposure to microgravity during space flight may lead to a state of structural and functional alteration in crewmembers skeleton system, which is manifested most clearly by the loss of bone mass and bone mineral, declines in bone mechanical function and negative calcium balance. These alterations were described as osteopenia induced by microgravity (OM) in the field of space life science. Even after several decades of extensive researches on OM, the basic mechanisms of the alterations in skeleton system have not been fully elucidated up to now. The key point of the countermeasures to OM is to promote the modeling of bone and slow the bone remodeling. Recently, findings indicate that mechanotransduction in bone cells is very important in the processes of bone reinforcement and resorption. We have confirmed the adverse effects of simulated microgravity on mechanotransduction in osteoblasts. The remain problems are how to understand the relationship of gravity and mechanical stress on the regulation process of osteoblasts. In this study, we purpose to clone the gravity and shear stress related genes from osteoblast-like human osteosarcoma MG-63 cells by subtractive hybridization.

Method MG-63 cells were divided into two groups (1G group and simulated microgravity group). After cultured for 60 h in two different gravitational environments, i.e. 1G terrestrial gravitational condition and simulated microgravity condition by using clinostat, two groups of MG-63 cells were treated with 1.5 Pa fluid shear stress (FSS) in a flow chamber for 60 min, respectively. The total RNA in cells was isolated and then was reversely transcripted into cDNA by BD SNART PCR cDNA synthesis kit. PCR-select cDNA subtraction was performed to establish the subtracted cDNA library. The gravity and shear stress related genes were cloned by subtractive hybridization. Result 200 clones were gained. 30 postive clones were selected using PCR method based on the primers of vector and sequenced. The obtained sequences were analyzed by blast. 17 sequences were confirmed by RT-PCR and these genes relate to cell proliferation and differentiation, protein synthesis, energy metabolism, and Ca2+ signaling. 5 unknown gravity and shear stress related genes were found and submitted to Genebank.

Conclusion In this part of our study, 17 known genes and 5 unknown genes were found to be the gravity and shear stress related genes. This result indicate that simulated microgravity may change the activities of MG-63 cells by inducing the functional alterations of specific genes. (Supported by NSFC: 30300398, 30570456, 30600132, 30700141)

Space biology involves wide range of studies on influence of different factors on the cell and molecular levels of biological systems, namely on genetic stability of growth and cell reproduction. Present work goes into problems on influence of clinorotation as one of tree factors of gravitation load.

Effect of microgravitation on viability and functional state of Namalwa human lymphoid cells infected by Epstein-Barr virus (EBV) was analyzed. Horizontal clinorotation of cells was carried out at 37 Celsius degree with speed 4 rpm (device «Clin - 1", "«Respirator", Donetsk) for modeling of microgravitation in ground conditions.

It was shown that microgravitation during 72 hours made no affect proliferative activity of lymphoid cells. When virus-cell system was constructed levels of EBV capsid protein uptake increased on influence of microgravitation. It is evidence of EBV reproduction enlarge in Namalwa cells.

Studies of clinorotation effect on spontaneous apoptosis phenomenon in Namalwa lymphoid cells were carried out. Apoptosis (programmed death) is characteristic peculiarity of organism development and life. It was determined that apoptosis increased sharply during acute infection of Namalwa lymphoid cells and after 72 hours it was 36% of apoptotic cells in comparison with control.

Thus present study effect of microgravitation on the apoptosis processes of EBV infected Namalwa cells demonstrates activation of cell DNA specific disintegration.

It is well documented that circadian rhythms in mammals are controlled by a central oscillator located in the hypothalamus. Studies have shown that the suprachiasmatic nucleus (SCN) serves as "master clock" in mammalian bodies controlling these circadian rhythms. SCN generated rhythms are based on the expression pattern of clock genes and their protein products. Theses clock genes are not only expressed in the SCN, but also in many extra-SCN brain regions and peripheral tissues. Numerous space studies carried out on rodents, monkeys, and humans have elucidated that space travel disturbs circadian rhythms, suggesting that changes in the gravitational environment can affect the circadian timing system in mammals.

The present study was focused on the effect of altered gravity on the expression pattern of clock genes in cultured rat-1 fibroblasts, a model cell system of the peripheral mammalian clock. These cells exhibit a circadian oscillation of the clock gene expression for several days after a transient serum shock. In the study, cells were exposed to normal gravity (1g), hyper-gravity (4g) created by a centrifuge and hypo-gravity (µg) simulated by a Random Positioning Machine (RPM). The expression profiles of the clock gene members Per2 and Bmal1 mRNAs in rat-1 fibroblast were investigated by using real-time PCR. Furthermore, immunocytochemical studies were carried out in order to additionally document morphological changes of the cells under the different gravitational conditions. Our results indicate that the clock genes of rat-1 fibroblast respond differently to hypo- and hyper-gravity, respectively. Although hyper-gravity did not change period and amplitude of the expression pattern in comparison to the 1g ground control, simulated microgravity caused a remarkable attenuation of the amplitude and an alteration of the period. Thus, our data clearly illustrate the sensitivity of peripheral clock genes to simulated microgravity. Further investigations need to be carried out in order define the underlying cellular mechanisms causing the observed effects.

The innate immune system plays a key role in defending the organism in early phases of infections and diseases. A defective immune response will increase the risk of diseases, cancer and can disturb the self regeneration of the body. The major task of the innate immunity, the removal of bacteria as well as infected, apoptotic and cancer cells, is realized by specialised cells - the phagocytes. They absorbed and digest intercellular pathogens and cell debris in intercellular phagolysosoms during phagocytosis. Decomposition is subsidized by the production of relative oxygen species (ROS) during the so called oxidative burst. To avoid collateral damage by excessive ROS-production but to ensure sufficient degradation of the ingested particles this immune reaction has to be controlled carefully and precisely. Past experience showed that microgravity has numerous effects on the immune reaction of whole organisms as well as on single cells. In earlier experiments we investigated macrophage phagocytosis behaviour during an initiated immune reaction. We found that microgravity significantly decreases the phagocytosis rate of the macrophage cell line NR8383 in the early phase, but cells adapt to their original rate in the late phagocytosis phase. Additionally, we examined the production of ROS in functional weightlessness conditions on a fast-rotating 2D clinostat. We could demonstrate that phagocytosis mediated oxidative burst is reduced up to half the normal rate, whereas the stress related oxidative burst in non- activated cells is increased up to the double amount. Until now, all these effects could only be documented in endpoint measurements. More detailed information on the process of phagocytosis and oxidative burst can only be gained by kinetic measurements. For this reason, we are currently adopting an existing clinostat microscope for real time monitoring of the described mechanisms. The aim is to gain kinetic data about the process of phagocytosis and oxidative burst reaction and changes of this reaction during due to functional weightlessness. Therefore 2D clinostat will be remodeled to accommodate cells and to monitor their behavior during clinorotation with a video device as well as with photomultiplier technique. Firstly, the phagocytosis of macrophages will be investigated in real time with fluorescence measurements during clinorotation. Secondly, we will monitor the progress of the phagocytosis-induced as well as stress-related oxidative burst reaction during clinorotation with chemi-luminescence measurements in real time. These new technical approaches enables us to adopt ground control measurements for the TRIPLE LUX flight experiment, which is planned to be carried out on the BIOLAB on the ISS in 2009. In this project the influences of microgravity and cosmic radiation on different model organisms are investigated by chemi-luminescence approaches. Application of the flight identical hardware allows us to compare data from the actual flight experiment with the kinetics of ground-based clinostat-measurements.

Cancer stem cells (CSCs) are considered a subset of the bulk tumor responsible for initiating and maintaining the disease. Saos-2 is a human sarcoma cell line that is used as a model for osteoblastic cells, which we have found to contain 10% of CD133(+) cells. CD133 is a transmembrane pentameric glycoprotein. It is a cell surface marker expressed by hematopoietic stem cells but not mature blood cells. It has also been found to be a marker for other stem and progenitor cells including neural and embryonic stem cells, and it is expressed in cancers, including some leukemias and brain tumors.

We isolated CD133(+) CSCs from the Saos-2 cell line by using a MACsorting system which consists of magnetic beads conjugated to an antibody against CD133 (Miltenyi, Auburn, CA). Saos-2 positivity to CD133 was assessed by Facs analysis using the BD FacsAria (Franklin Lakes, NJ). One million Saos-2 CD133(+) MACsorted cells were cultured using DMEM with 10% fetal bovine serum (FBS), in an Hydrodynamic Focusing Bioreactor (HFB) (Celdyne, Houston, TX) which was developed by NASA at the Johnson Space Center, and a 14-fold proliferation was observed in a seven-day run. In comparison, one million unsorted Saos-2 cells, which were by Facs analysis 90% CD133(-) and 10% CD133(+), were also cultured in the same conditions in the HFB for a seven-day run. We observed a 14-fold proliferation of the CD133(+) cellular fraction. Additionally, 100% of the harvested cells were found to be CD133(+), indicating that the HFB had selected for the Saos-2 undifferentiated cellular fraction. As a control, we also cultured CD133(-) Saos-2 cells in the HFB for a 7-days run and found that we were unable to recover any viable cell.

The HFB selected and proliferated CD133(+) Saos-2 cells were also grown in soft agarose plate media, and as a 1G control suspension culture using low-attaching Petri dishes. The CD133(+) Saos-2 cells grew as sarco-spheres which is a typical stem cell growth feature. Additionally, the expression levels of more stem cell markers other than CD133 were tested before and after a seven-day run in the HFB. Sparc, Sox-9, RunX-2, Stro-1, CD117, and Integrin-ß1 showed an increase of expression after a seven-day run when compared to the static growth control. The HFB provides a unique hydrofocusing capability that simultaneously enables a low-shear culture environment and a hydrofocusing-based suspension of cells which allows the CD133(+) cells to selectively grow undisturbed.

It has been reported that microgravity leads to some kind of deficiency of the biological function in clinical use and suppresses the differentiation of various types of cells in vitro. In spite of recent advances in medical science, glioblastoma is still refractory to treatment. Therefore, we hypothesized that culture of glioblastoma cells under the simulated microgravity may inhibit its proliferation.

A 3D-clinostat is a multi-directional gravity device used for simulating microgravity. By controlled rotation of two axes, a 3D-clinostat minimizes the cumulative gravity vector in cells cultured at the center of the device and makes 10-3 G average over time. We examined the effect of simulated microgravity on proliferation of three types of glioblastoma cell lines (D54MG, U251MG, and T98G) using a 3D-clinostat.

Initially glioblastoma cells were harvested in normal 1G condition. Proliferated cells were, then, cultured in a 3D-clinostat and normal 1G environment for 3 days, respectively. The cells were examined for their growth pattern, mitochondrial activity and the cell cycle difference. Additionally we investigated whether exposure to simulated microgravity influence the chemosensitivity to cisplatin using MTT assay.

The growing rate was significantly inhibited in a 3D-clinostat, without cell cycle change. Moreover, mitochondrial activity was inhibited in a 3D-clinostat. Thus, proliferation of glioblastoma was inhibited probably due to its decelerated mitotic rate when cultured in a 3D-clinostat. Chemosensitivity to cisplatin in microgravity exposure group was significantly enhanced compared to 1G environment group. Glioblastoma are still seriously difficult to treat and control. We suggest that the effect of microgravity may be of assistance to control glioblastoma.

Near-infrared light (NIR) has been used widely in laser form to treat a variety of injuries, especially infected, ischemic, and hypoxic wounds. More recently, NIR light-emitting diode arrays that were developed for NASA to promote plant growth in space were tested for their therapeutic effect on animal tissues. We hypothesized that the mechanism of biological action of NIR is via the endogenous mitochondrial enzyme, cytochrome c oxidase (COX), a known photoacceptor in the near-infrared range. Postnatal cortical neurons in primary cultures were functionally inactivated by tetrodotoxin (TTX), a voltage-dependent sodium channel blocker. A brief 80 sec exposure to NIR-LED (at 4 J/cm2 energy density and 50 mW/cm2 power intensity) each day for 5 days recovered neuronal COX activity and ATP content, suppressed by TTX, to control levels. However, increasing concentrations of potassium cyanide, an irreversible inhibitor of COX, yielded progressively less benefit by the NIR-LED treatment and increasing numbers of apoptotic cell death. On the other hand, NIR-LED pretreatment for 10 min (30 J/cm2) before KCN exposure (28 hours) reduced the number of apoptotic neurons by ~50%. When various wavelengths of LED were tested, the most effective ones (830 nm; 670 nm) paralleled the NIR absorption spectrum of oxidized COX, whereas the least effective one (728 nm) did not. These results are consistent with our hypothesis that the mechanism of photobiomodulation involves the up-regulation of cytochrome c oxidase, leading to increased energy metabolism in neurons functionally inactivated by toxins.

The generation of high-energy free radicals from radiations or changes in oxygen/intermediary metabolism produces an increase in oxidative stress during spaceflight. This oxidative damage seems to be due to the decreased synthesis or depletion of antioxidant defences, particularly of glutathione, an important endogenous antioxidant. In the frame of FOTON M3 mission, supported by ASI (Italian Space Agency) we were present with the experiment SCORE (Saccharomyces Cerevisiae Oxidative-stress Response Evaluation). In collaboration with Thales Alenia Space a suitable automated device was developed and produced.

This flight opportunity allowed us to examine the effects of spaceflight on cellular response of yeast, a simplified and well-built model in which metabolic adjustment to oxygen/substrate modulations is very efficient. Aim of the experiment was to evaluate differences in oxygen/intermediary metabolism of yeast grown in microgravity under normoxic or hyperoxic culture conditions. SCORE experiment was completely successful, from the engineering and biochemical points of view. All the critical features of a spaceflight payload were doing well and worked properly. Medium analyses definitely validate our microgravity simulation results. Preliminary results indicate changes in the distribution of buds, activation of MAP Kinase pathways and enhancement in protein carbonylation.

In the frames of Russian-American Foton M3 experiment 15 female geckos were studied: in flight, basal and synchronous control groups of 5 animals. Brain was fixed in 10% formaldehyde, embedded in paraffin and 10 mcm serial sections were prepared. They were stained according to Mallory and Nissl and with hematoxylin-eosin and also the immunohistochemical methods with antibodies to the nerve growth factor receptor (NGF-r), glial fibrillary acid protein (GFAP), S-100 protein. Attention was paid to vestibular nuclei of rhombencephalon, for in weightlessness changes and damage in the centers of linear acceleration could be expected. Behavior was studied by comparison of flight group to the delayed synchronous control.

Examination of the sections of rhombencephalon revealed cytological changes in the neuron bodies of vestibular nuclei inside the flight group. In the peripheral cytoplasm of the bodies of vestibular neurons there was noted intensive vacuolization (up to a third of the cell section) - evidence of extreme metabolic loading of the cells. These changes are mostly expressed in the large neurons of the ventrolateral nucleus (nucleus vestibularis ventrolateralis), but are also seen in other nuclei of vestibular area (n. vestibularis descendens, n. vestibularis dorsolateralis). The study of the neurons of acoustic area, reticular formation of brainstem and other nuclei of the rhombencephalon failed to reveal strong cytological changes, while single neurons of the medial nucleus of reticular formation of rhombencephalon displayed traces of metabolic loading. Geckos of both groups remained motionless more then 95% of time, while attached by finger pads to the walls of the container (either rest or one of two poses of attention). In the flight group there was single observation of attachment by means of one leg and twice the long-lasting flotation. In all cases the animals remained calm and made no attempts to contact with the container surface. Also no aggressive interactions were noted in any of the groups and no cases of offensive posture were recoded. The stress level may be estimated as low for both groups and adaptation to the spaceflight considered successful. So most of flight time the animals remained attached to the walls receiving normal motor information.

In conclusion, combination of histological and ethological methods allowed to reveal the misscoordination of motor and vestibular apparatus under influence of space flight.

In terrestrial gastropod snail Helix lucorum L. we studied the changes in behavior after a 16-day (Foton M-2) and 12-day (Foton M-3) exposure to microgravity. For investigation of behavioral changes we choose a natural "negative gravitaxis" responses that consisted in rapid movement of the snails from the head down position to head up position. It was found that the latency of body position change to sudden orientation change (flip from horizontal to downwards position - "head down") was significantly reduced in the postflight snails. Comparison of averaged latencies of the behavioral responses at the separate 2 phases for the negative gravitaxis response for the flight and control snails showed significant differences in performance. Flight snails were significantly faster in their response to "head down" stimulation at each phase (p <0.05; nonparametric, two-tailed, unpaired Mann-Whitney test).

These results suggest the existence of changes in the statocyst of the postflight snails. In addition to this general test for locomotion we tested the changes in latency in similar context with added vibration that was associated with food presentation to the hungry snails. After a period of learning the snails showed significantly faster locomotion in the positively reinforced context (vibration+). Comparison of changes in postflight and control snails trained in different contexts showed only tendency for difference, possibly due to small number of animals tested. Obtained results suggest a possibility to analyze changes in behavior and memory due to microgravity exposure using this simple model animal.

Skin deterioration is one of the major detrimental effects experienced by astronauts in space. The skin being the largest organ of the human body and serving as its protective shield is highly susceptible to harmful environmental influences. In order to understand the effects of space conditions on the human skin, it is important to unravel the underlying cellular mechanisms altered. For this purpose, the Foton M3 RADCELLS experiment focussed on the damaging effects of space radiation and microgravity on human dermal fibroblasts. The Foton M3 is a robotic spacecraft that flew at low orbit around the Earth for 12 days in September 2007. Within the Foton M3, samples were mounted into a biobox which was devised so that part of the samples experienced 0g whereas the other part resided in a 1g centrifuge as internal control. 3 cell types of human dermal fibroblast origin were tested: one wildtype (the human normal fibroblast cells (NHDFc)) and two human mutant fibroblast cells with impaired nuclear architecture (lamin knock-out and Hutchinson-Gilford Progeria patient).

By the use of the multiplex array assay, culture supernatants of space and ground cultures were submitted to a thorough study of 89 proteins (chemokines, cytokines, interleukins, metalloproteinases, tumor markers) involved in inflammation, cancer development, metabolism and various cardiovascular processes.

The results show variations in the chemokine concentrations in comparison with the ground control for pro-inflammatory cytokines, like IL-1 beta, TNF-beta and RANTES; for metalloproteinases associated with inflammation, like MMP-2, MMP-9 and TIMP-1; for a few tumoral agents (like CA 19-9) as well as for some hormones involved in metabolism like insuline.

In conclusion, we show that cosmic radiations and microgravity differently affect the inflammation and tumorigenicity pathways. Furthermore, the three fibroblast cell types showed a different response to space conditions underlining the importance of nuclear organization in damage control and stress response. The current results therefore indicate that the individual and combined effects of cosmic radiation and microgravity involve complex interdependent biological mechanisms, particularly involved in the inflammation and in cancer development. This research is financially supported by a PRODEX/ESA contract (C90-303).

Basing on the results of investigations made in the interests of space medicine, IBMP has developed several means and methods to improve the mechanisms known as primarily affected during such neurological diseases as children's cerebral palsy, ischemic stroke and secondarily - during the reduction of motor activity followed by immobilization associated with certain pathologies. The mechanical support stimulator (MSS) or "Medical boots" was one of the first "space" developments adopted by neurological clinics to create mechanical stimulation of the foot support zones the same way as during slow or fast walk. Theoretical basis for the method was laid in the investigations of mechanisms of the motor disorders in microgravity. It was shown that consequent reduction of afferentation from the support receptors are responsible for a dramatic drop in the activity of tonic motor units at the initial (immediate) phase of exposure and the resulting decline in muscular tone which, further on, bring about structural atrophic changes in slow muscular fibers.

The MSS imitates the feet afferentation, obtained by natural walking with their physical action on the feet receptors. During mechanical support stimulation there were stimulated the calcaneum and instep support zones of feet at patients and healthy subjects. The distribution and temporary characteristics of the pressure were imitating the natural walking. The mode of slow walking was used (75 steps/min).

20 patients with acute stroke were included in this study. The control group consisted of 10 patients which received only traditional rehabilitation. The basic group consisted of 10 patients which additionally received 10 sessions of mechanical support stimulation (for 20 minutes). The electromyographic activity of leg muscles, muscle transverse stiffness was analyzed.

We have used the functional MRI to assess the afferent input obtained by mechanical support stimulation at 6 healthy subjects. Functional MRI was made in a block-design at 1.5T tomograph (Symphony, Sciemens) with alternation of the feet stimulation (30 sec) and the rest period (30 sec) during 3 min for the left, then the right foot, then for both feet in the treatment regimen imitating walking. The data were analyzed using SPM5.

The studies performed at a neurological clinic evidenced that shortly after the ischemic stroke a distinct asymmetric changes in the electromyographic activity and muscle tone dominated in flexor and extensor muscles were registered. Mechanical stimulation of the foot support zones on the pattern of natural locomotion cancelled out this muscle tone asymmetry.

The functional MRI analysis demonstrated the activation of the contralateral sensorimotor area while the one foot stimulation. The stimulation of both feet leaded to bilateral activation of the superior parietal lobes besides the activation of the corresponding sensorimotor cortex. So the walking imitating with MS SFZ obtained another activation pattern than the stimulation of only one foot.

May be for the better recovery of movement we need in another approach than just physical exercises. The walking imitating with mechanical support stimulation supply the qualitative another afferentation than just stimulation of one foot, which demonstrates the involvement of the another pathways obtaining better recovery

Navigation is an everyday occupational activity for human when we, for example, drive from home to work. Navigating movements evoke sensations in the visual, vestibular and proprioceptive systems, giving us the perception of motion. Evolution and a lifetime of experience on Earth seem to have imposed a gravitational 'priming' of the internal reference frames used by the brain to organise spatial memory. The electroencephalogram (EEG) study of navigation on Earth and in space may provide new understanding of how gravity-related information is processed and how our perceptions are built. In humans, real and apparent motions in the depth direction elicit specific negative visual evoked potentials (VEP) occurring with latencies of 150-200 ms (N200) and recorded over the right lateral occipital and posterior parietal cortex. Theta oscillations (4-8 Hz) have also been shown to be involved in navigation tasks both in rodents and virtual maze learning in humans. We investigated on Earth and in weightlessness the evoked potentials and the related spectral perturbations of EEG oscillations during a task of virtual navigation. Seven cosmonauts participated in this investigation during missions to the International Space Station (ISS) of 10 days (4 subjects) to 6 months (3 subjects). Each cosmonaut was tested on the ground before and after flight and aboard the ISS. Subjects looked straight ahead through a form-fitting face-mask at a computer screen where a 3D tunnel was presented as a virtual navigation stimulus. The EEG was measured using an electro-cap with 14 Ag-AgCl electrodes (Halley system). The EEGs were filtered (0.01-100 Hz) and sampled at 256 Hz. EEG analyses were performed off-line with the EEGLAB software. Four control subjects were also analyzed on Earth. All cosmonauts exhibited the motion VEP (N200) with an identifiable negative component in response to movement onset when tested on the ground.

Inter-trial coherence analysis revealed the presence of a significant synchronization in theta-alpha band (3-13 Hz), time-locked with the stimulation and occurring with latency around N200. In the ISS, during the first week of flight and for the majority of the cosmonauts, the N200 decreased for tests performed while free-floating. This effect was accompanied by suppression of theta-alpha phase-locking. In contrast, when strapped in a seated position, N200 and phase-locking of the theta-alpha rhythm remained unchanged. It is interesting to see that after 3 months of flight the N200 and the synchronization of the EEG rhythms reappeared even during free-floating. Another major effect of weightlessness was a strong increase in the gamma oscillation (35Hz-50Hz) that appeared for the movement-in-depth event and that remained stable during 2 seconds, until the appearance of the subsequent visual stimulus. These results suggest that theta waves in humans are involved in spatial processing of sensory information relative to a frame of reference. On the other hand, the increase in the power of gamma rhythms in 0G could confirm the thought that this rhythm emerges from somatosensory areas enhancing perception acuity, and in cognitive processing. As in previous works in the literature, our results suggest that gamma oscillations are superimposed on theta oscillations during exploration of a new environment.

The objective of this study is to measure the impact of vertigo due to vestibular dysfunction on space missions:

KEYWORDS: µg body adaptation, ergonomics, design, visual orientation, bed rest, parabolic flight

ABSTRACT: Taking into account the difficulties of orientation reported by astronauts in microgravity, in the chair of Human-Machine Systems of the Technische Universität Berlin it is studied an experiment named WIUD. Considering that in microgravity the orientation becomes achievable only visually since the vestibular system becomes silent, the WIUD experiment is focused on visual stimuli.

WIUD acronym means "Where is Up and Down". It is born as a phase of a European team project called µgOrienting for the investigation of orientation and motion perception in microgravity.

This experiment studies instinctual reaction towards colors and symbols for up and down orientation. In a "bed rest" posture (1) facing a monitor positioned in the ceiling on a sample of subjects is asked to indicate the up and down in relation to different visual context. In particular those subjects will have to up and down orient a human icon in a context of different colors and symbols configuration proposed in the monitor.

The color and symbol configuration that will be selected during this phase will be applied for the orientation in free floating conditions in the second phase of the European project called ZEROgYMN.

The application of the µgOrienting project are related ergonomic research for space habitability (2).

The goal of the participation in the "Life in Space for Life on Earth" conference is to approach an international committee of experts in the field of gravitational physiology in order to improve the project methodology. Nonetheless human adaptation to outer space life is still an unknown and complicated challenge that needs the consultation of not easy to find experts.

(1) The subject lies in a bed inclined -6 degree feet up, that is normally used to study the physiological reaction at microgravity condition.
(2) Visual stimuli like color and sign may be the key factor not only for the orientation but also to increase the overall habitability for long duration missions under floating condition. In the ISS, Russians and Americans have different standard for the design of labels as for the labels of up and down orientation, the consequential visual pollution increase the orientations problems of the astronauts.

During exposure to linear acceleration of the body in the dark, visual objects are seen shifted from their true physical locations. This oculogravic illusion is directly associated with a misperception of body pitch and is generally thought to be generated primarily by otolithic signals. The otolithic system cannot discriminate gravity from other non-gravity dependent linear accelerations. Patients with vestibular loss also experience oculogravic illusions but of lesser magnitude.

Somaesthetic mechanoreceptors, proprioceptors, receptors in internal organs, and cardiovascular blood distribution all influence the perception of body orientation. The present study further explored the potential role of such non-vestibular factors in the oculogravic illusion. In two experiments, we adjusted the position of subjects on a centrifuge and its velocity of rotation to generate a gravitoinertial force (GIF) to the otolithic system differing in magnitude from the GIF applied to the rest of the body. In the first experiment, the subjects were positioned on their back in a chair like apparatus mounted on a turntable. Their upper legs were vertical and their lower legs horizontal.

The body was positioned to generate a 1.2 GIF resultant vector either at the otolith organs or closer to the body center of mass. In the second experiment, a 1.2 GIF resultant at the otolith organs was achieved with the body in different configurations, the entire body supine or the trunk supine with the legs elevated, and with head positioned toward or away from the axis of rotation. Subjects remotely positioned a visual target to the zenith, the apparent visual vertical. Our findings indicate that the oculogravic illusion is systematically modified by GIF dependent somaesthetic stimulation when otolithical stimulation is held constant.

KEYWORDS: µg body adaptation, visual orientation, ergonomics, design, bed rest, parabolic flight.................................................................................................................................................................... ABSTRACT: In microgravity under floating condition, where up and down have no meaning, orientation is a primary prerequisite. In this conditions of physical adaptation, the sense of orientation and motion become achievable only through the visual perception, since the vestibular signal after 3 days becomes silent (Mallove, 1991). In a newly born project called µgOrienting, a european team of expert from France, Germany and Italy are carrying out a research on visual orientation for human space missions( ).

As sequential phases of the project tree experiments have been considered: CROMOS, WIUD and ZEROgYMN.
- The CROMOS experiment was successfully accomplished in 2007 during the ESA Student Parabolic Flight Campaign. This experiment analyzed the modification of visual perception in 0g condition. The result of this experiment will be used as basis for the next phases of the projects now at the proposal stage.
- The WIUD research is carried out, on a bed rest facility, to study instinctual reaction towards color and symbol for up and down orientation. The color and symbol configuration that will be selected during this phase will be applied to the orientation in free floating conditions in the third phase of the project: ZEROgYMN.
- In ZEROgYMN project, made on parabolic flight facility, a group of rhythmic gymnastics students will perform expressive movement and examine visual input for the improvement of orientation and movement perception.

The overall goal of the µg Orienting project is to study visual stimuli potentials for the orientation and movement perception in microgravity condition. The project combines research on microgravity visual perception with rhythmic gymnastics during free floating movement.

(1) Visual orientation for human space mission: Such knowledge is aimed at ergonomically-oriented spacecraft design, taking into account the bio-mechanics of the middle and inner ear and the function of the equilibrium organ's architecture in relationship to gravity. The consequent field of study becomes the development of an interest for human factors in technological environment design and in the adaptation of man in his challenge to live in outer space.

It is now well established that the adult sensorimotor cortex is a highly plastic structure. In particular, a 14-day period of simulated microgravity, obtained by hindlimb suspension in rats, produces a reorganisation of cortical maps: a shrinkage of the foot representation area and an enlargement of receptive fields are observed. In addition, the response of cortical cells to peripheral stimulation is higher. We have also previously shown that the expression of neurotrophins (NGF and BDNF) is increased following 14 days of simulated microgravity. However, our comprehension concerning the cellular and molecular mechanisms of this reorganization is still limited.

Recently, the interest was turned towards intracellular signalling pathways. Among these pathways, one major is implied in controlling neuronal survival, differentiation, growth and neuronal plasticity: the MAPKinase (Mitogen-Activated Protein Kinase) cascade. This cascade is activated in response to many neurotransmitters and growth factors and more specifically following binding of NGF to TrkA receptors. In addition, the downstream effectors of the MAPK pathway include activation of fos immediate early gene, which expression is increased after 14 days of microgravity.

Thus, the aim of the present work was to study key-markers of the MAPK cascade (ERK, JNK and p38) after different periods of simulated microgravity (0, 7, 14 and 28 days). The expression levels of total and phosphorylated (activated) forms of these proteins were evaluated by western blots using antibodies. In parallel, we determined the cortical area of the foot representation and the extent of receptive fields. Our results indicate that the activation levels of MAPK markers were increased from 0 to 14 days of simulated microgravity, and then returned to control values after 28 days. Interestingly, the foot cortical area evolves in parallel to the MAPK: a first step of shrinkage (from 0 to 14 days) is followed by a second step of extension (from 14 to 28 days), where the foot area returns to control values.

These results indicate that MAPK cascade members could be implied in the cortical plasticity induced by simulated microgravity. They may help to develop strategies aimed to attenuating the effects of disuse on the central nervous system.

This work was supported by grants from the Centre National d'Etudes Spatiales and the Nord-Pas de Calais regional council.

We show for the first time how rat hypothalamic neurons respond to the moderate-low gravity environments such as those encountered on the surface of the Moon and Mars. The unit activities of rat hypothalamic arcuate nuclei (ARC) were measured by telemetry through chronically implanted microelectrodes in freely moving rats during parabolic flights. The flight was operated for four continuous days, using 4 rats each. Rats were renewed for each day of flight. Rats experienced four different levels of low gravity from 0.4G through 0.01G. Each parabolic trajectory was repeated three times with enough intervals aboard the same flight. Rat behavior was monitored throughout the flight by digital video cameras. Rats were calm throughout the flights.

The rat hind limbs were slightly floated only upon entry into 0.01G. The firing frequencies of ARC neurons were analyzed statistically on each low gravity level (paired and unpaired t-test). The rat ARC significantly responded to the moderate-low gravity of 0.15G and lower, suggesting the low-gravity responsive threshold of rat ARC. The rat ARC did not respond at all to the high gravity conditions that were generated during the nose up and recovery processes of each parabola. The Moon surface might be a quite delicate gravitational environment to regulate switch on and off the neuronal activity in rat hypothalamus. We found previously that the hypothalamus responded most sensitively in rat limbic system against low gravity environment during parabolic flights. Our data suggest the mechanisms underlying the stress response in the hypothalamus to low gravity, and predict a potential neuronal response on the Moon surface. Supported by grants from the Japan Space Forum Foundation FY2006-2007, and the Ministry of Science, Sports, Education, and Culture of Japan FY2006-2007, to Y. Kumei.

Exposure to altered gravitational environment, especially during critical ontogenetic phases, may affect neurobehavioural development in mammals. Data from life science missions clearly indicate that rodents are able to provide parental care to their offspring while in the space, and that dam and neonates can interact successfully under conditions of microgravity. However, improvements are needed in the nest-area in order to facilitate mother-offspring interactions and guarantee a proper pups development.

In the present work, CD-1 dams with their litters were exposed to 1 hr rotational induced hypergravity (1 or 2 g) and maternal behaviour before, during and after the rotation was observed. Moreover, somatic and behavioural profile of developing pups were assessed recording the ultrasonic vocalization pattern, exploratory performance in an open-field test and social interactions.

Several items of the maternal repertoire were selectively affected by hypergravity exposure, and the somatic growth of rotated pups as well as ultrasonic vocalization profile appeared clearly compromised by exposure to rotational stimuli.

Alteration in exploratory and social behaviour were also observed confirming a subtle but consistent effects of early exposure to changes in gravitational environment on mouse neurobehavioural profile as a whole. Data will be discussed in term of habitat development, appropriate experimental paradigms and systematic ground-based testing prerequisites to future research with young postnatal rodents in space.

It has been shown that the available information about the relationship of gravity to the different body parts would augment the information about their mutual relationship. In weightlessness, the absence of gravity-determined cues like otoliths cues about head orientation and, tactile and visceral cues about trunk orientation requires the substitution of other sensory information. The aim of the present study was to investigate the ability of human's subject to accurately locate the head relative to the trunk in microgravity. Experiments were conducted during two separated sessions: 1) on earth and, 2) during parabolic flights. Subjects were asked to adjust a visual rod until it looked parallel to their head or trunk axis in two different segmental configurations: head and trunk aligned or head tilted. These results suggested that, in microgravity, the visual egocentric perception depends on the segmental configuration. Although the proprioceptive signals from neck muscles seem sufficient to provide accurate head on trunk information, the visual egocentric co-ordinates were deviated toward the head tilt. This experiment provides evidence for the role of gravity on the visual perception of head- and trunk-based egocentric coordinates.

Long duration space flights have provided a considerable amount of scientific research on human ability to function in extreme environments. Findings indicate that long duration missions take a toll on the individual, both physiologically and psychologically, as entry into a gravitationless environment and living in it is a novel situation for humans which the body may perceive as stress. Medical interest in exercise as an adjunct treatment in depression has recently re-emerged. Special attention was given to alterations in the serotonergic (5-HT) system which has complex neuromodulatory functions and is known to act as a multifunctional generator for the adaptation of e.g. mood, vigilance and performance.

The aim of the present study is to investigate in healthy but confined subjects the influence of exercise with/without increased carbohydrate, competitive branched-chain amino acids (BCAA) or Tryptophan (TRP) intake, on the 5-HT system and its implications on mood and mental and perceptual motor performance. Responses of the 5-HT system will be evaluated by measuring the peripheral markers TRP and the density/affinity of 5-HT transporters and 5-HT2A receptors at blood platelets before and after the training programs. Post-stimulation prolactin concentrations will also be assessed as the secretion of this hormone is affected by brain 5-HT activity. Effects of exercise with/without supplementation on mood, motivation and psychological strain will be monitored using physiological markers (e.g. EEG, HR-variability) as well as psychological markers (MoodMeter®, a tool for the assessment of physical and psychological states). Effects of exercise and confinement on performance will be assessed using the Vienna Test System.

We hypothesize that impairments in mood due to the isolated and confined environment together with a lack of physical exercise lead to decreases in mental and perceptual motor performance whereas physical exercise linked with an activation of the serotonergic system will improve mood and therefore performance irrespectively of the environmental restrictions.

Exposure to microgravity is a well-known stressor to both animals and humans. However, the precise level of low gravity capable of evoking emotional change has not been clearly defined. Analysis of behavior can provide clues to an animalâ™s emotional status. In this study, we examined in rats the behavioral response to different levels of low gravity, from 0.4 G to 0.05 G. Wistar albino rats weighing about 230 g were exposed to low gravity during parabolic flights. Each flight consisted of 12 parabolas, and each parabola had a specific low gravity target. The rats were placed in individual acrylic cages and had their behavior monitored by video cameras. As part of a larger protocol, the rats had been implanted brain electrodes 5 to 7 days before the flights, and had wires and transmitters attached to their backs during the flights. The rats were startled by the changes in gravity from 0.2 G and lower. At 0.15 G and lower, the rats showed signs of distress such as spreading the legs and stretching the tail, and micturition. The level of 0.15 G seemed like a threshold for stressful behaviors in rats. The data suggest that although the Martian gravity level was undisruptive, the Lunar gravity level may be around the critical threshold that induces behavioral changes in rats. Supported by grants from the Japan Space Forum Foundation FY2006-2007, the Ministry of Science, Sports, Education, and Culture of Japan FY2006-2007, to Y. Kumei, and the Japan Society for the Promotion of Science FY2007-2008 to J. L. Zeredo.

We previously reported that gravity stimulation induced emotional disturbance in rats. Behavioral nociceptive responses were strongly modified after gravity stimulation in freely moving rats. This suggests that gravity stressful stimulation may modify various sensory systems closely related to emotion including chemical sensation. In the present study, effects of high-gravity loading on the feeding pattern and chemical sensation were investigated.

Methods;EXP.1: Adult rats (39-69d) received gravity stress (1.6, 2.0, 2.4G) every 10 min/day during 30 days. EXP.2: Rats (24-68d) loaded 3G or restraint every 10 min/day during 44 days. Tastant tests were started at 45d after birth. Sucrose, saccharin, NaCl, caffeine, quinine, citric acid, MSG, capsaicin were used as chemical solutions. MF powder diet balanced for rats (Oriental Yeast, Tokyo, Japan) were used to investigate feeding behavior.

Results:EXP.1: The increasing pattern of body weight was significantly suppressed in relation to magnitudes of the loaded gravity. Food intake and food intake/100g body weight were decreased during 10 days in case of 2.0 and 2.4G loading. Food efficiencies were also significantly decreased in 1.6, 2.0 and 2.4G loaded groups. The intake volume of caffeine and capsaicin was increased after gravity loading. EXP2: The increasing pattern of body weight was suppressed at maximum by 3G loading. Food intake/100g body weight was decreased by 3G loading. In addition, food efficiencies were decreased by restraint and 3G loading. The 3G loading significantly modified the chemical sensation of saccharin, NaCl, caffeine, quinine and capsaicin. Data suggest that the long-term high gravity loading is critical for modification of chemical sensation.

The adult organisms chronically exposed to a change in the gravity levels on either side of the homeostatic 1 g they undergo on earth, show physiological modifications in relation with the increasing variations across the spectrum of gravity. Early investigators considered the alterations of the gravitational field as a continuum, on the basis of consistent observations in various organisms at increasing gravity levels. This principle of continuity was never rigorously tested in a careful evaluation of the reactions of a single species to increased gravity levels. The present study evaluated the reactions of mice to increasing levels of gravity, with the aim to verify the existence of a continuum in the reactions, and to determine the type of responses that are gravity specific and the responses that depend on an overall reaction the environmental change. The present study analysed the behavioural changes of adult male mice C57bl6/j subjected to a chronic exposition at various gravity levels. Series of 12 mice were continuously centrifuged at 2, 3 and 4 g level for three weeks. 4 mice were sacrificed at leaving the centrifuge for tissue analysis, 8 mice returned to 1g for two weeks to avoid any short term reaction to the ambient change. After that period, they were subjected to a thorough evaluation of their behavioural performance, in a large set of tests. The present study reports the behavioural responses of mice measured in vivo in the tests of motor and vestibular performance, and in a series of tests to evaluate their level of stress, cognitive and memory performance. A comparative analysis of the behavioural reactions of mice centrifuged at increasing g level is discussed in relation with the hypothesis of a continuum in the reaction to hypergravity as hypothesized by the principle of continuity.

In this project a cage design is being proposed in which mice can be housed in a microgravity environment. The cages are refered to as MIS cages (Mice In Space). The objective of this paper is to describe and evaluate the proposed cage design, by investigating the micro-environment within such a MIS cage, and to quantify the difference in activity between single and double housed mice by using integrated cameras in the top covers of the cages and quantifying the differences in stress levels by fecal hormone extraction. By assessing the gradients in air circulation in the cage, it can be visualized that high air flow gradients exist within the MIS cage. Measuring the 3D temperature distribution showed small temperature gradients, being maximum 0.1° C. The effect of individual or double housing on activity was quantified with images recorded during 25 day trials. There was a significantly difference observed as single housed show 40% more activity compared to double housed mice. No significant difference was found in stress levels between MIS housed mice and control mice, suggesting the proposed design is acceptable for housing mice. The technical description in this paper should allow researchers to be informed about the possibilities that will come available to do mice experimentations in space. THIS IS AN ESA-FUNDED PROJECT

Low extracellular concentration of glutamate in brain is normally maintained between times of exocytotic transmission in order to prevent desensitization of receptors and to avoid exitotoxisity. The tonic (unstimulated) release of glutamate may be functionally important and include spontaneous exocytosis of glutamate, the release of glutamate via swelling-activated anion channels and possibly by reversal of high-affinity Na+-dependent glutamate transporters. The tonic release of glutamate from rat brain synaptosomes decreased insignificantly after hypergravity loading of animals and consisted of 4.0 ± 0.5 % of total label in control and 3.8 ± 0.5 % in hypergravity. In the next set of experiments to stimulate the glutamate release we used the protonophore FCCP, which dissipated the proton gradient across synaptic vesicle and thus synaptic vesicles were not able to keep glutamate inside and the neurotransmitter was released into cytosol. 1 microM FCCP induced the release of 4.8 ±1.0 % and 8.0±1.0 % of total accumulated synaptosomal label in control and G-loaded animals, respectively. To investigate further the FCCP-evoked L-[14C]glutamate release the ability of the transporter inhibitor DL-TBOA to reduce the L-[14C]glutamate release was evaluated under control and hypergravity conditions. DL-TBOA inhibited FCCP-evoked L-[14C]glutamate release that was expected to result from the inhibition of glutamate transport mediated by reversal of glutamate transporters. Application of 10 microM DL-TBOA reduced 58.0 ± 4.0 % of L-[14C]glutamate release induced by FCCP for 2 min in control and 73.0 ±4.0 % after centrifuge-induced hypergravity. Thus, it is reasonable to conclude that the release of glutamate stimulated by FCCP was transporter-mediated release, which increased in hypergravity, and DL-TBOA inhibited this release more effectively under hypergravity conditions than in control.

BACKGROUND: The vestibular labyrinth organ probably is the most important gravisensor for adequate postural and performance control body stability as well as head movements including vesitibulo-ocular reflex mechanisms on Earth (1G). In microgravity conditions (µG) such as in spaceflight, however, afferent and efferent vestibular informations such as tonic skeletal muscle control are clearly suppressed which may result in perturbed muscular structural and functional properties that need to be determined in more detail. AIM OF STUDY: Two months after bilateral labyrinthectomy (LBx) in rats (n=6) we investigated if chronic lack of vestibular efferent muscular reflexive control would significantly alter cross-sectional area (CSA) and distribution of slow vs. fast fiber type patterns in hindlimb postural m. soleus. Sham-operated animals (n=6) served as controls. RESULTS: Our major findings were that (i) LBx rats showed significantly increased numbers of slow fibers identified by high-resolution confocal analysis in 8µm thick cryosections using ALEXA-coupled slow vs. fast myosin-heavy chain immunostaining (slow vs. fast MyHC) as compared to sham-OP control animals (p<0.01). (ii) Digitized morphometry of dystrophin / slow-fast MyHC double-immunostained myofiber cross-sectioned profiles (250 fibers per animal) combined with slow/fast myofiber distribution confirmed that fast>slow fiber transition must have occurred resulting in much slower m. soleus following LBx vs. Sham-OP (p<0.05). CONCLUSIONS: We conclude that bilateral LBx affected both myofiber size and type distribution pattern in m. soleus significantly. PERSPECTIVE: Further analysis e.g. impaired autonomic control mechanisms that may link the labyrinth and its target skeletal muscles are in progress.

The utricular organ senses the sum of inertial force due to head translation and head tilt relative to the gravitational vertical. A change in force has a profound effect on how an organism maintains equilibrium, and the neural response might involve the peripheral otolith receptors, the brain or both. If the influence of µG leads to adaptation and subsequent re-adaptation in otolith function upon return to 1G, then: does the transfer from 1G to 3G impart the opposite effects on changes of structure and function response seen following µG exposure? Do the effects accompanying transfer from 3G to 1G conditions resemble in part (as an analog) the transfer from 1G to µG?

Here we record the impulse response of utricular afferents to servo-controlled linear accelerations and tilt profiles in the anesthetized oyster toadfish, Opsanus tau, after 1-, 2-, 3-, 4-, 5-, 8- and 16-day exposure to 3G centrifugation, and following 1-8 days recovery to study re-adaptation to 1G. Typically >60 afferents are well characterized in each animal. Afferents were also examined during electric shocks applied to the efferent vestibular pathway at rest and during motion tests. In each fish 45-60 horizontal canal afferents are also studied to yaw. Synaptic body counts in striolar and extrastriolar hair cells are performed on serial sections of the macula using transmission electron microscopy. Results to date show a biphasic pattern: an initial sensitivity up-regulation (3- and 4-day) followed by a significant decrease after 16-day exposures. Return to control values following 16-day exposure is on the order of 4 days. A significant decrease by 50% in hair cell synaptic bodies is observed between control and 16-day exposure fish. The otolith sensitivity to acceleration is clearly regulated by altered gravity exposure, and indicates that this paradigm might be used to study the neural and behavioral responses, including the response to countermeasure intervention, to altered gravity in a ground-based model. (Supported by NASA: 03-OBPR-04.)

Previous studies have shown that both snails and fish develop larger statoliths and otoliths in microgravity. Similarly, we have found that zebrafish reared for 4 d in a rotating wall vessel (RWV; the NASA-designed ‘bioreactor’) also develop larger saccular and utricular otoliths when compared to control zebrafish reared in stationary vessels. When the RWV was rotated at 18.5 rpm around a horizontal axis, the zebrafish eggs were suspended in nearly circular orbits, thereby averaging the directional vector of gravity to simulate conditions of microgravity. However, zebrafish also developed larger otoliths when reared in the RWV spun at 26.5 rpm, when the eggs were forced against the outer wall, and at 8.5 rpm, when the eggs tumbled along the bottom of the vessel. In contrast, otoliths were not significantly larger in zebrafish which had been reared in the RWV spun at 18.5 rpm, but around a vertical axis, when compared to zebrafish reared in stationary vessels. These results thus suggest that enlarged otoliths develop under several conditions, in addition to microgravity, when randomized or continuous otolith movements occur within the otic vesicle. Our results emphasize the need for multiple controls when interpreting the effects of simulated microgravity.
(Supported by Canadian Space Agency Contract 9F007-046016.)

An experimental study on the relationship between the inner-ear fluid pressure and the semicircular canal afferent nerve discharge in toadfish (Yamauchi et al, 2002, Rabbitt et al, 2001) showed that afferents are very sensitive to the transcupular endolymphatic pressure (Pt) and to the dilational labyrinthine pressure (Pd). The corresponding threshold sensitivities were about 0.001 Pa for Pt and 0.05 Pa (by 1 imp/s for 2 Hz pressure stimuli) for Pd. Experimental results were supported by structural modeling of the ampulla structure, assuming that the shear moduli of a cupula and a membranous labyrinth wall are 0.36 Pa and 300 Pa respectively , and Poisson ratio=0.5. It was found that the Pd sensitivity of afferents is determined by the nonuniform cupular deformation caused by the pressure-induced distension of the ampulla. Cupula deformation resulted in the deformation of underlying hair cells.

The perilymphatic space was opened in this experiment. Thus a modulation of the ambient pressure in an experimental chamber induced the direct modulation of the perilymphatic pressure (PP). Meanwhile: i) the labyrinthine pressure in the vertebrates is mainly constrained by the bony walls of an otic capsule, and ii) its relationship with the ambient pressure is very complex and not clearly understood. The present work focuses on the following two questions. 1) A simple mathematical model of the influence of inner-ear pressures on the behavior of a "cupula-endolymph" system in the horizontal canal duct immersed in a bony labyrinth is analyzed. Estimates based on the theory of elasticity show that for the mentioned values of Pd and shear moduli, and for Poisson ratio that is insignificantly < 0.5, the threshold deformations of a cupula are comparable with those in the case of an open perilymphatic space. However their spatial distributions are different. Furthermore, an assumed difference of cupula and endolymph compressibilities will result in a specific gravity difference between a cupula and endolymph, i.e. a canal sensitivity to linear acceleration. It can occur if the Poisson ratio of cupula < 0.499999. 2) Endolymphatic and perilymphatic pressures are known to be closely correlated in normal conditions. PP changes should directly influence endolymph pressure. At the same time the PP is influenced by the cerebrospinal fluid pressure (CFP). CFP fluctuations are transmitted to the ear via the cochlear aqueduct and endolymphatic duct, and can occur with the change of ambient pressure, respiration, posture changes, coughing, sneezing, etc. A qualitative model of the CFP pressure regulation in response to the change of ambient pressure is discussed. (Partially supported by NASA: 03-OBPR-04)

Space Motion Sickness (SMS) is the most clinically significant phenomenon occurring during the first few days of space flight. The usual symptoms include nausea and vertigo. Little is known about the cellular mechanisms that underlie this sickness. Endolymph in the inner ear fills the sensory vestibular organs. It's an unusual extracellular fluid in that its composition is reminiscent of cerebrospinal fluid. K+ provides the major charge carrier for sensory transduction and is ideal in this function, since it is by far the most abundant ion in the endolymph. We hypothesized that endolymphatic K+ variations may have a role in SMS. To investigate this question, we first placed adult rats under hypergravity conditions (2g) during 20 days in a centrifuge. Animals exposed to hypergravity develop a transient syndrome of vestibular behaviour abnormalities. Using a behavioural test battery, we studied occurrence and disappearance of this abnormal behaviour. We then developed experimental models in vitro (three-dimensional culture of mice utricle) and in vivo (selective K+ microelectrode chirurgical implantation in the rat vestibule) to evaluate the effects of gravity modification on the endolymphatic K+ concentration and potential. In vitro, preliminary results show a small decrease of K+ concentration in the utricular culture placed under hypergravity conditions (2g) for 3 days. We also investigated the effect of microgravity on utricular culture using Rotary Cell Culture System (RCCS). The first results show a large decrease of K+ concentration in this culture placed in RCCS from 2 to 7 days in vitro. Preliminary results will be presented at the meeting.

This work was supported by the Centre National des Etudes Spatiales and Ministčre de la Recherche et des Nouvelles Technologies. MC was supported by a PhD grant from CNES. The terrestrial centrifuge is in collaboration with GSBSM Toulouse.

Introduction: Space Motion Sickness (SMS) is commonly experienced by astronauts and often requires treatment with medications during early flight days of space missions. Orally administered scopolamine is commonly used by astronauts to prevent SMS. Bioavailability of oral (PO) SMS medications is often low and highly variable. Intranasal (IN) administration of medications achieves higher and more reliable bioavailability than from an equivalent PO dose.

Methods: In this study, pharmacokinetics of three escalating doses of intranasal scopolamine (0.1, 0.2, 0.4 mg) were examined in twelve healthy volunteer subjects in a completely randomized, double blind, crossover clinical study design. Scheduled plasma samples were collected for 24 hours post dose and analyzed by mass spectrometry (LCMSMS).

Results: Maximum concentrations, Cmax, and the area under the plasma concentration versus time curve, AUC, increased linearly with dose in all subjects. Clearance, volume of distribution, and tmax were similar for all doses. Males had lower plasma concentrations and resultant AUC; volume of distribution was higher in males than females. Higher bioavailability and linear pharmacokinetics coupled with a low incidence of side effects makes INSCOP a desirable formulation for prophylactic and rescue treatment of astronauts in space and military personnel on duty.