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Objectives: We review the studies that have evaluated intermittent short-radius centrifugation as a potential countermeasure for cardiovascular, musculoskeletal, and sensorimotor deconditioning in simulated weightlessness. Methods: The findings from 18 experimental protocols that have used bed rest and dry immersion for comparing the protective effects of centrifugation versus standing upright or walking, and the effects of continuous vs. periodic exposure to centrifugation are discussed. Results: Centrifugation for as little as 30 min per day was found to be effective in mitigating orthostatic intolerance and strength in postural muscle after 5 days of bed rest, but it was not effective in mitigating plasma volume loss. Conclusion: To determine the optimal prescription for centrifugation as a countermeasure, we recommend further studies using (a) bed rest of longer duration, (b) individualized prescriptions of centrifugation combined with exercise, and (c) functional performance tests.

Objectives: There is ample agreement that the specific shape of a bone is related to the loads it has to carry. It is also believed that bones mechano-adapt in order to ‘find’ this shape. The open question is which signals constitute the determinants of this adapation. Recent in vivo experiments show that torsion is a significant load component in human tibia, and a computational study of the mechanostat has indicated that torsion could play a role in the shaping of tubular long bones. Methods: An earlier computational approach is further progressed to systematically study the relative importance of axial compression, lateral bending and axial torsion. Results: Results demonstrate that shapedriving potential towards tubular shapes is greatest for torsion, followed by bending and least for axial compression. Multiple linear regression analysis confirmed the dominant role of torsion, in particular for the 2nd moment of intertia. The obtained results were largely unaffected by starting conditions, e.g. either from a grid or through reshaping under disuse. Conclusions: Strong support has been found for the hypothesis torsion could be more important than suggested in previous studies as a component of the mechanical environment of bones. This will apply to the shafts of long bones, and also to the femoral neck

Objectives: Spaceflight back pain and intervertebral disc (IVD) herniations cause problems in astronauts. Purpose of this study was to assess changes in T2-relaxation-time through MRI measurements before and after head-down tilt bed-rest, a spaceflight analog. Methods: 8 men participated in the bed-rest study. Subjects remained in 6° head down tilt bed-rest in two campaigns of 21 days, and received a nutritional intervention (potassium bicarbonate 90 mmol/d) in a cross-over design. MRI measurements were performed 2 days before bed-rest, as well as one and five days after getting up. Image Segmentation and data analysis were conducted for the IVDs Th12/L1 to L5/S1. Results: 7 subjects, average age of 27.6 (SD 3.3) years, completed the study. Results showed a significant increase in T2-time in all IVDs (p < 0.001), more pronounced in the nucleus pulposus than in the annulus fibrosus (p

Objectives: We hypothesized that progressive whole-body vibration (WBV) superimposed to progressive high intensity resistance training has greater effects on muscle cross-sectional area (CSA), muscle force of leg muscles, and jump performance than progressive high intensity resistance training alone. Methods: Two groups of healthy male subjects performed either 6 weeks of Resistive Vibration Exercise (RVE, squats and heel raises with WBV, n=13) or Resistive Exercise (RE, squats and heel raises without WBV, n=13). Squats under RVE required indispensable weight loading on the forefoot to damp harmful vibrations to the head. Time, intervention, and interaction effects were analyzed. Results: After 6 weeks of training, knee extensor CSA, isometric knee extension force, and counter movement jump height increased equally in both groups (time effect, P

The authors propose a new 3D interpolation algorithm for the generation of digital geometric 3D-models of bones from existing image stacks obtained by peripheral Quantitative Computed Tomography (pQCT) or Magnetic Resonance Imaging (MRI). The technique is based on the interpolation of radial gray value profiles of the pQCT cross sections. The method has been validated by using an ex-vivo human tibia and by comparing interpolated pQCT images with images from scans taken at the same position. A diversity index of

Einleitung: Seit etwa 10 Jahren ist bekannt, dass es nach Langzeitaufenthalten im Weltraum zu charakteristischen Veränderungen der Augen kommt, welche u.a. Hyperopie, Bulbus-Verkürzung und Aufweitung der Sehnervenscheide umfassen. Zusätzlich ist bei einer Reihe von Astronauten ein erhöhter Liquor-Eröffnungsdruck nach Rückkehr auf die Erde festgestellt worden. Insbesondere die letzten beiden Befunde legen nahe, dass den Augenveränderungen ein erhöhter intrakranieller Druck zugrunde liegt. Kopfschmerz, Übelkeit und Schlafstörungen, welche oft von Astronauten berichtet werden, könnten zumindest teilweise durch Hirndruck verursacht sein. Und auch die vermutete kognitive Leistungseinbuße in der Schwerelosigkeit wäre theoretisch durch erhöhten Hirndruck erklärbar. Es stellt sich deshalb die Frage, ob es in der Schwerelosigkeit in der Tat zu erhöhtem Hirndruck kommt, und welche physiologischen Mechanismen an der Erhöhung beteiligt sein könnten. Ergebnisse aus dem Weltraum: Bei Astronauten sind kopfwärts gerichtete Flüssigkeitsverschiebungen seit langem bekannt, die u.a. zum sogenannten ‚puffy face‘ führen. Allerdings sind die Ursachen hierfür nicht verstanden. Eine mögliche Erklärung wäre jugular-venöse Stauung, welche auch jüngst an Astronauten beobachtet worden ist. Diese könnte wiederum durch Verlust der Retraktionskräfte am Thorax, bedingt durch den ‚Gewichtsverlust‘ der Eingeweide, und damit durch eine Abflussbehinderung in den venae subclaviae verursacht sein. Erhöhter Druck im Sinus sagitalis führt nach dem gegenwärtigen Verständnis der Liquor-Zirkulation zur Verminderung der Liquor-Resorption, und damit zum erhöhten Hirndruck. An Ratten wurden nach Aufenthalt in der Schwerelosigkeit Veränderungen des plexus choroideus gemessen,welche gut zu erhöhtem Hirndruck passen würden. Demgegenüber sei aber auch erwähnt, dass invasive Messungen des Hirndrucks im Parabelflug ein Erniedrigung und keine Erhöhung gezeigt haben. Dieser Effekt ist wegen seines raschen Eintrittes (binnen Sekunden) aber wohl eher physikalischanatomisch als physiologisch zu erklären. Schließich sei noch erwähnt, dass die erhöhte CO2-Konzentration in ursächlichem Zusammenhang zum Auftreten von Kopfschmerzen auf der Raumstation steht. Ergebnisse aus bodengestützten Studien: In der Abteilung ‚Weltraumphysiologie‘ haben in den Vergangenen Jahren in einer Reihe von Studien das Modell der Kopftieflage genutzt, um für die Raumfahrt relevante Effekte der kranialen Flüssigkeitsregulation zu studieren. Die wichtigsten Ergebnisse aus diesen Arbeiten waren: 1) Kopftieflage führt zu venöser Stauung und Reduktion der arteriellen Durchblutung; 2) Kopftieflage führt zur vermehrten Ansammlung von Liquor im Kranium; 3) letzterer Effekt kann durch lower body negative pressure unterbunden werden. 4) Kopftieflage führt, vermutlich durch kraniale Minderdurchblutung, zur Reduktion der kognitiven Leistungsfähigkeit. Schlussfolgerungen: Das Thema Hirndruck ist für die Gesundheit und Leistungsfähigkeit von Astronauten vermutlich von größerer Bedeutung als bisher angenommen. Die Ergebnisse aus den bodengestützten Studien untermauern die mögliche Rolle von ugularvenöser Stauung.

Experiences in long-term flights on space stations have provided evidence that the longer the space mission, the more important become psychological factors, the required knowledge about these factors, and their changes. During the flight, when psychological monitoring is most important and needed, it becomes mostly difficult. The methods used should be objective, non-obtrusive, non-disrupting, mission related, useful for crew itself (immediate expert-system based feedback) as well as that they should be neither tedious nor artificial nor abstract, so that they will not be avoided but accepted by the crew. There is a heightened need for new measurements and methods which are objective, reliable, computerized, continuously, or at least repeatedly, applicable in order to achieve – in a perfect setting - monitoring of nearly all behavior and performances during a mission. Irrespective if and how psychological monitoring is to be fully understood, it must first be viewed as an essential support tool for the crew, parallel to the technical monitoring systems e.g. of fuel and water quality. Rigorous selection of the crew favors those who are tough, enduring, well-trained, performance-oriented, and unaccustomed to “needing” the help of psychologists. Although these participants are honest in subjective self-evaluation, they tend to exhibit repression. This requires re-thinking, and re-evaluation of psychological methodology. Presently, psychological monitoring focuses usually only on performance in special and common tasks, for example docking training, or have a scientific background. We still only have limited methods to objectively monitor all the indicators mentioned. Sensitive observation and private conversation based on a trusting personal relation between ground and crew remain the most important. Likewise, the monitoring of group cohesion and group conflict should focus on the group dynamics, cultural life, events, group activities, sub-group separation. For an autonomous decision making of the crew, an independent computerized support system on board could be a great assistance not only for technical problems. There are first successful and promising attempts in video face emotion analysis. Voice frequency analysis is a very promising approach for space psychology. Voice cross analysis could indicate the common and individual amounts of communication but also the emotional states and reactions of the speakers. A wireless group structure monitoring could provide information about the dynamics of the crew structure during the mission. Work sample analysis represents an already well established method and is used as a routine monitoring. Really mission relevant skills (e.g. the hand controlled docking of a space craft on a space station or catching a free flying object by means of a hand controlled robot arm) are refreshed and trained during the mission, thus, providing information about the proficiency of the operators and about their actual motivational state. If this professional monitoring is associated with a physiological strain assessment, an indirect monitoring of the psychophysiological state is provided. It seems possible to implement features of embedded testing of fundamental cognitive functions into these refreshment trainers. However, areas such as automated daily duty analysis, analysis of the cooperation quality during shared duties, analysis of readiness and progress in coping with expert-system feedback or learning new things (e.g. the language of crew mates or new skills) as well as a spare time use analysis are currently only at the proposal level.

Einleitung: Eine Otitis externa kommt gehäuft bei Personen vor, die sich in feucht-warmen Klima aufhalten, z. B. Schwimmer oder Taucher. Dass die Teilnahme an einer Langzeit-Bettruhestudie in -6° Kopftieflage (LBS) zu einer erhöhten Inzidenz der Otitis externa führt, ist bisher nicht beschrieben. Fragestellung: Inzidenz der Otitis externa im Kontext von LBS. Methodik: Fallserie Ergebnisse: 4 von 23 Probanden entwickelten innerhalb einer 60 tägigen Bettruhestudie eine akute Otitis externa, die durch eine antibiotische Therapie mit einem Fluorchinolon, antiphlogistischer Therapie und Reinigung des Gehörgangs während der Bettruhe erfolgreich therapiert werden konnte. Schlussfolgerungen: Eine Otitis externa kann zu einer deutlichen Einschränkung des Probanden führen und damit den wissenschaftlichen Erfolg einer LBS beeinträchtigen. In zukünftigen LBS sollte die Inzidenz für Infektionen des Kopfes systematisch erfasst und mögliche Vermeidungsstrategien gesucht werden.

INTRODUCTION: In former joint space studies of the IBMP, RSC Energia and the Institute of Aerospace medicine (DLR) on MIR and ISS cardiovascular measures were registered to assess the physiological cost of cosmonauts during their docking training. In parallel the fundamental frequency of voice was analyzed to obtain information about the unconscious subjective evaluation of the subject’s perception of situation control. The results of the studies onboard MIR and ISS provided evidence that the docking training did not increase “voice-stress” indicators or indicators of enhancement of the cardiovascular arousal. As far the performance of the cosmonauts was rather good this could be seen as an valid indication of cosmonaut’s proficiency and their expectable reliability in running a docking maneuver. As a next step a very classic but robust Event Related Potential (ERP) design was implemented. We tested the possibility to use the component P300 to assess and monitor the individual cognitive difficulty of operators in a certain docking task. The space study is still in preparation; a ground based study was run. It was expected that during difficult tasks the secondary task is performed worse and the P300 has smaller amplitude and longer latency. METHODS: The study was run within the complex “:envihab” of the DLR. The participants were volunteers. The test session consisted of 6 standard tasks (condition “easy”) and one really difficult task (condition “difficult”). A training model of the flight hardware in the Russian segment of the ISS was used. An EEG-electrode system with active dry electrodes was applied. RESULTS: The magnitude of the P300 was smaller and its latency was larger for the difficult task than for the easier task. We consider it important, that is was possible that for the P300 differences statistical significances could be assessed within single subjects using all evoked EEG-episodes for each channel. CONCLUSIONS: In a ground-bases study we demonstrated the possibility to assess the cognitive difficulty by means of the ERP component P300. This additional psychophysiological assessment could improve the performance and behavioral assessment during the docking training and thus enhancing mission safety.

INTRODUCTION We describe a case of recurrent urinary retention (UR) during 12 degree head down tilt (12° HDT) bed rest during the 2-campaign Space-COT study. CASE A 47 yr. healthy ♂ subject with no previous urological conditions developed recurrent, UR during 12° HDT. The first episode occurred 3 h after transition from upright to HDT. A bladder ultrasound scan confirmed a highly distended bladder. The subject was given further time to void but developed lower abdominal pain, and was still unable to void. A disposable straight catheterization was performed to empty the bladder, which returned > 1000 ml of urine with immediate relief of discomfort. During the next urinary collection, the subject was again not able to urinate in HDT position. Thus the decision was made to place an indwelling urinary catheter (Fig. 2). The catheter was placed uneventfully, but had to be removed the following night on request of the subject due to persistent urethral discomfort. On the following day, it was decided by the medical team to allow temporary interruption of the 12° HDT angle to facilitate urination. At 10° head up tilt (HUT) the subject easily urinated. Using this procedure, the subject had no further issues of urinary retention during the first campaign. In preparation for campaign 2, one week later, the subject was given a large 12° wedge (Fig. 1) and urinary bottles to practice micturition at home. He reported no voiding disturbances in HDT position at home. During campaign 2, the UR immediately reappeared during HDT, and resolved with body angle change to supine position. DISCUSSION UR has been reported for spaceflight [1, 2] but not for HDT bedrest. Given in our case that UR appeared only during 12° HDT during the study, but not in the same position at home suggests that situational anxiety played a role. Alternatively, it is possible that the subject had an undiagnosed urological condition that may have contributed to urinary dysfunction, along with psychological stress; however, no previous urological symptoms had ever been reported. CONCLUSION UR, particularly during 12° HDT bed rest, can compromise study success but may be excludable in advance by testing the 12° HDT urination procedure during the medical selection process of the subjects.