This page provides
a list of poster presentations in the field of of gravitational life sciences
(biology / physiology), astrobiology, physical sciences or closely related disciplines
that were presented by or in collaboration with Dutch investigators.
Please note that this page has to be updated to provide a complete overview
of research undertaken from within Dutch universities and other research institutes.
Input from you as a scientist / participant in the various studies is very much
appreciated.
Some of the papers
presented here are in PDF format and may be downloaded and printed. When you
do not have a PDF reader please click PDF icon
2004
• Andreescu CE*, De Zeeuw CI, De Jeu MTG. Department of Neuroscience, Erasmus MC, Rotterdam. Keeping balanced in space. 3rd Endo-Neuro-Phycho meeting and 8th Endo-Neuro meeting, June 1-4, 2004, Doorwerth, The Netherlands
Abstract:
On earth the sensory information from the vestibular system, the optokinetic system and the proprioceptors is necessary to maintain balance and a stable retinal image. In space the sensory information provided by the otolith organs is absent or very small due to the lack of gravity (microgravity). Here, on earth, we studied the influence of gravity and the consequences of gravity perception loss on eye movements using a mutant mouse lacking the otoconia, which serve as the gravito-inertial loading of the otolith organs (the tilted mouse, tlt). The horizontal and vertical vestibulo-ocular reflex (VOR), optokinetic reflex (OKR) and visually enhanced vestibulo-ocular reflex (VVOR) were recorded in tlt and control littermate mice, using a video eye-tracking technique. Furthermore, otolith sensitivity was studied by positioning the mouse in different roll angles. The otolith-ocular responsiveness to various gravitational forces was significantly attenuated in the mutant mice, indicating that these mice do not have functional otolith organs. VOR gains were lower and VOR phases were higher in tlt mice compared to littermates, regardless of the head position with respect to gravity. In all tested conditions the OKR gain in tlt mice was significantly higher than in the control mice, with no phase difference between the two groups. Despite the higher OKR gain in the tlt mice, the mutant mice couldn’t reach the VVOR gain of the control mice. The increased OKR gain is a frequency dependent compensatory mechanism, which is not influenced either by the position of the mouse or by the eye movement plane. This study clearly reveals that there is a functional synergy in the processing of otolith and optokinetic signals regarding the gravito-inertial acceleration. This mechanism might also be important for maintaining balance and stable retinal images in space.
*Corina E Andreescu, Department of Neuroscience, Erasmus MC, 3000 DR Rotterdam, PO Box 1738, The Netherlands, t 0630003170, e-mail c.andreescu@erasmusmc.nl. See the poster for this abstract.
2001
• Veldhuijzen J. Paul , Jolanda M.A. de Blieck-Hogervorst and Jack J.W.A. van Loon. Response of cultured fetal mouse long bones to random positioning.Dept. of Oral Cell Biology, ACTA-Vrije University, Amsterdam, The Netherlands. ASGSB seventh annual meeting, Alexandria, VA, USA, November 7-10, 2001.
Abstract:
Recently a Random Positioning Machine (RPM) has been developed (Dutch Space (former Fokker Space), The Netherlands) which should provide simulated microgravity conditions. Effectiveness of the RPM to duplicate the results of our real microgravity experiments where bones showed a clear reduction in mineralization, was tested in cultures of 17-day old fetal mouse bones. The bones were cultured “free floating” in double layered polyethylene culture bags (0.7 ml medium); 8 of these bags were placed in standard flight hardware in Biorack type I containers. Containers with control cultures were placed on the non-moving frame of the RPM. Initially no effects of the RPM were found. However, the “free floating “ bones went through uncontrolled movements during RPM-operation. Immobilizing the bones in small pieces of agarose gel prevented these movements of the bones and agarose did only marginally affected growth and mineralization of these bones. Experiments with these immobili-zed bones showed that overall growth of the bones on the RPM did not change. In most experiments again no differences were found in the mineralization. However in the RPM-groups in many cases the standard deviation was higher then in the controls. In some experiments we found indeed a decrease in mineralization; in another experiment we found an increase. This leads to the conclusion that the RPM did not provide simulated microgravity to the cultured long bones. However in the culture bags always air bubbles were present. Under real microgravity these bubbles do not move and do not affect the culture but on the RPM these bubbles revealed to be very mobile. This will have changed culture conditions on the RPM, which could have obscured possible effect of the RPM. Further experiments are needed to clarify this issue. (Supported by the Space Organization of the Netherlands (SRON): MG-045/3).
• Veldhuijzen J. P., J. M.A. de Blieck-Hogervorst and J.W.A. van Loon. Effectiveness of the Random Positioning Machine (RPM) to provide simulated microgravity for cultured fetal mouse long bones Dept. of Oral Cell Biology, ACTA - Vrije University, Amsterdam, The Netherlands. ELGRA Biennial Meeting and General Assembly Banyuls sur mer (France), September 25-28, 2001.
Having the possibility to perform experiments in the laboratory under simulated microgravity conditions would be a great advantage in microgravity research. Recently a Random Positioning Machine has been developed (Dutch Space (former Fokker Space), The Netherlands) which should offer simulated microgravity conditions. Previous experiments with cultured fetal mouse long bones under space flight conditions (IML-1, IML2 and BION-10) revealed that 4 days of real microgravity did not change overall growth but reduced the mineralization of the diaphysis. Effectiveness of the RPM to duplicate the results of our flight experiments was tested in 4-day cultures of 17-day old fetal mouse long bones in real flight hardware. The long bones were individually cultured in double-layered culture bags with 0.7 ml medium (alfa-MEM including 5% FCS and 2-3 mM Na-ß-glycerophosphate). Experiments were performed in Biorack type I/0 containers, each with 8 culture bags. The content of the container was flushed with air/5% CO2 at the beginning of the experiment and, in a number of experiments, again after 2 days. Prior to the experiment and at the end, photomicrographs were taken of each individual long bone. These photographs were used for measurements to calculate the increase in overall length and length of the mineralized diaphysis. In space flight experiments the isolated long bones are not attached inside the culture bag but in the RPM this resulted in movements of the long bones that should be avoided in true random positioning. Experiments with these "mobile" long bones did not show any difference in growth and mineralization between the RPM and control cultures. We were able to prevent these movements by immobilizing the long bones in a small piece of agarose gel. Overall growth was never changed under RPM-conditions. In most of the experiments also no differences in the mean values for mineralization on the RPM and under control conditions were found. However in the RPM-groups in many cases the standard deviation was higher then in the controls. In some experiments comparable results were found as under real microgravity conditions (decreased mineralization), whereas in another experiment the mineralization seemed to have increased on the RPM. The inability to reproduce the results of our flight experiment on the RPM leads to the conclusion that the RPM did not provide simulated microgravity to our fetal mouse long bones. However during the introduction of the agarose-immobilized long bones into the culture bags it was in most cases impossible to avoid also the inclusion of air bubbles. These air bubbles do not affect culture conditions under real microgravity or in the controls of the RPM-experiments. In the culture bags on the RPM however, these bubbles are very motile during RPM-operation and may have mixed the medium, resulting in different culture conditions, which may have obscured possible differences between the RPM-groups and the controls. Further experiments are needed to clarify this issue. This project was supported by the Space Research Organization of the Netherlands (SRON grant MG-045)
2000
• Hypergravity modulates body composition. N. Bravenboer1, H. de Jong, R. Wubbels, A.M. Tromp, H.W. van Essen, J.W.A. van Loon, A. van Lingen, P. Lips. 22nd Annual Meeting of the American Sociaty for Bone and Mineral Research (ASBMR). Toronto, Ontario, Canada, Sept. 22-26 2000. (PDF file, 34kB)
Abstract:
Mechanical stress is a major determinant of bone mass and bone architecture. Subjecting animals to sustained acceleration in a centrifuge, leading to an increased gravitational force (hypergravity or HG) results in changes of various parts of the organism 1 . HG decreases body weight in the long term while food intake is only decreased in the first few days of HG. Anatomical examination of HG animals shows a pronounced decrease in body fat, particularly in the abdominal fat depots and the lipid content of internal organs 2 . Concerning bone mass the literature is equivocal. Some studies show shorter femur length, indicating that hypergravity inhibits the longitudinal growth 3 . Jaekel et al 4 show a higher bone mineral density resulting in a better capability to withstand mechanical stress.
1999
• van Loon J..J.W.A, Mastenbroek O., Lemcke C. The Biopack Facility. 'Life Odyssey' 7th European Symposium on Life Sciences Research in Space, 29 May to 2 June 1999. Maastricht, The Netherlands. (PDF file, 856kB)
• van Loon J..J.W.A, van Hulst N.F. Atomic Force Microscopy as Tool in Cell Biological research for Ground Based and In-Flight Studies. 'Life Odyssey' 7th European Symposium on Life Sciences Research in Space, 29 May to 2 June 1999. Maastricht, The Netherlands. (PDF file, 705 kB)
• Wubbels R.J. and H. A. A. de
Jong. Vestibular induced behaviour of rats born and raised under hypergravity
conditions. 'Life Odyssey' 7th European Symposium on Life Sciences Research
in Space, 29 May to 2 June 1999. Maastricht, The Netherlands. ESA-SRON publication
Introduction:
Rats were bred in a centrifuge, simulating a hypergravity (HG) environment of 2.5 times normal gravity (NG), to investigate how the vestibular system is affected by long-term HG conditions. There is no acute distress among centrifuge-bred rats when the centrifuge is stopped, because all animals immediately become very active.
The airrighting reflex (turning from a supine to prone position during fall) and the reappearance at the surface after falling into a water basin were observed (IR illumination). Both types of behaviour depend on the capability to orientate relative to the direction of gravity. The question is: Is this behaviour affected by the ontogenetic development of the vestibular system under HG conditions? (full paper)