The data from the R3DE instrument of ESA’s EXPOSE-E mission outside the ISS at the European Technological Expose Facility (EuTEF) on the ESA Columbus module shows that the docking of the Space Shuttle with the International Space Station (ISS) decreased the South-Atlantic Anomaly (SAA) maxima dose rates from about 1500 Gy h-1 down to 600-700 Gy h-1 or by factor of 2. The dose rate data at the same time from another Bulgarian built instrument (R3DR) of the EXPOSE-R mission outside the Russian “Zvezda” module showed that: 1) before the Space Shuttle docking, the SAA dose rates measured with R3DR were higher (2500 Gy h-1) than the R3DE data; 2) The relative decrease of the SAA dose rates after the shuttle docking was only by a factor of 1.25. These differences are explained by the smaller shielding of R3DR from the body of ISS and by the larger distance of it from the body of Space Shuttle. Very similar data, but with smaller dose rates were obtained with a third Bulgarian built instrument (Liulin-5) inside Russian “Pirs” module. The analysis of the ascending/descending SAA dose rate maxima of the three instruments shows that the effect can be simply explained by the additional shielding against the 30 to 150 MeV protons of the SAA, provided by the 78 tons Shuttle to the instruments and by changing of the ISS 3D mass distribution when the ISS rotates.
Research Containing: Electron
The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the per- iod February 20 – April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°–60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 lGy h 1 behind 1.75 g cm 2 shielding at Foton M2, 2314 lGy h 1 behind 0.71 g cm 2 shielding at Foton M3 and 19,195 lGy h 1 (Flux is 8363 cm 2 s 1) behind les than 0.4 g cm 2 shielding at ISS.
Operational radiation protection for astronauts and cosmonauts and correlated activities of ESA Medical Operations
Since the early times of human spaceflight radiation has been, besides the influence of microgravity on the human body, recognized as a main health concern to astronauts and cosmonauts. The radiation environment that the crew experiences during spaceflight differs significantly to that found on earth due to particles of greater potential for biological damage. Highly energetic charged particles, such as protons, helium nuclei (“alpha particles”) and heavier ions up to iron, originating from several sources, as well as protons and electrons trapped in the Earth's radiation belts, are the main contributors. The exposure that the crew receives during a spaceflight significantly exceeds exposures routinely received by terrestrial radiation workers. The European Space Agency's (ESA) Astronaut Center (EAC) in Cologne, Germany, is home of the European Astronaut Corps. Part of the EAC is the Crew Medical Support Office (CMSO or HSF-AM) responsible for ensuring the health and well-being of the European Astronauts. A sequence of activities is conducted to protect astronauts and cosmonauts health, including those aiming to mitigate adverse effects of space radiation. All health related activities are part of a multinational Medical Operations (MedOps) concept, which is executed by the different Space Agencies participating in the human spaceflight program of the International Space Station (ISS). This article will give an introduction to the current measures used for radiation monitoring and protection of astronauts and cosmonauts. The operational guidelines that shall ensure proper implementation and execution of those radiation protection measures will be addressed. Operational hardware for passive and active radiation monitoring and for personal dosimetry, as well as the operational procedures that are applied, are described.
We studied the growth of metal-ion silicate chemical gardens under Earth gravity (1 g) and microgravity (mug) conditions. Identical sets of reaction chambers from an automated system (the Silicate Garden Habitat or SGHab) were used in both cases. The mug experiment was performed on board the International Space Station (ISS) within a temperature-controlled setup that provided still and video images of the experiment downlinked to the ground. Calcium chloride, manganese chloride, cobalt chloride, and nickel sulfate were used as seed salts in sodium silicate solutions of several concentrations. The formation and growth of osmotic envelopes and microtubes was much slower under mug conditions. In 1 g, buoyancy forces caused tubes to grow upward, whereas a random orientation for tube growth was found under mug conditions.
A biaxial rotating bioreactor for the culture of fetal mesenchymal stem cells for bone tissue engineering
The generation of effective tissue engineered bone grafts requires efficient exchange of nutrients and mechanical stimulus. Bioreactors provide a manner in which this can be achieved. We have recently developed a biaxial rotating bioreactor with efficient fluidics through in-silico modeling. Here we investigated its performance for generation of highly osteogenic bone graft using polycaprolactone-tricalcium phosphate (PCL-TCP) scaffolds seeded with human fetal mesenchymal stem cell (hfMSC). hfMSC scaffolds were cultured in either bioreactor or static cultures, with assessment of cellular viability, proliferation and osteogenic differentiation it) vitro and also after transplantation into immunodeficient mice. Compared to static culture, bioreactor-cultured hfMSC scaffolds reached cellular confluence earlier (day 7 vs. day 28), with greater cellularity (2x, p < 0.01), and maintained high cellular viability in the core, which was 2000 Inn from the surface. In addition, bioreactor culture was associated with greater osteogenic induction, ALP expression (1.5x P < 0.01), calcium deposition (5.5x, p < 0.001) and bony nodule formation on SEM, and in-vivo ectopic bone formation in immunodeficient mice (3.2x, p < 0.001) compared with static-cultured scaffolds. The use of biaxial bioreactor here allowed the maintenance of cellular viability beyond the limits of conventional diffusion, with increased proliferation and osteogenic differentiation both in vitro and in vivo, suggesting its utility for bone tissue engineering applications. (C) 2009 Elsevier Ltd. All rights reserved.
<Go to ISI>://WOS:000264953900005
Utilization of the aquatic research facility and fertilization syringe unit to study sea urchin development in space
Methods were developed for the investigation of the effects of microgravity on early development in sea urchins within the Canadian Space Agency's Aquatic Research Facility (ARF). The ARF payload provided light, temperature control, automated fixation capability, and a 1 G on-orbit centrifuge control. Eggs and embryos of either the sea urchin species Lytechinus pictus or Strongylocentrotus purpuratus were loaded into Standard Container Assemblies (SCAs) which comprised the experimental aquaria (33 mL volume) contained within the ARF. A newly developed Fertilization Syringe Unit (FSU) was used to achieve "in-flight" fertilization capability. Fixative solutions were preloaded into fixation blocks maintained adjacent to the SCAs and injected at pre-selected time points, resulting in final (diluted) concentrations of either 0.5% or 2% glutaraldehyde (depending upon embryonic stage). Light, scanning, and transmission electron microscopy determined that all desired embryonic and cell division stages (16-cell stage, blastula, gastrula, and pluteus) were preserved using the experimental protocols and fixation capability provided by the ARF/FSU system.
Formation and differentiation of three-dimensional rat marrow stromal cell culture on microcarriers in a rotating-wall vessel
Using a high aspect ratio vessel (HARV), this study investigated the formation of 3-D rat marrow stromal cell culture on microcarriers and the expression of bone-related biochemical markers under conditions of simulated microgravity. In addition, it calculated the shear stresses imparted on the surface of microcarriers of different densities by the medium fluid in an HARV. Secondary rat marrow stromal cells were cultured on two types of microcarriers, Cytodex-3 beads and modified bioactive glass particles. Examination of cellular morphology by scanning electron microscopy revealed the presence of three-dimensional multicellular aggregates consisting of multiple cell-covered Cytodex-3 microcarriers bridged together. Mineralization was observed in the aggregates. Spherical cell-bead aggregates were observed in an HARV, while cell-bead assemblies were mostly loosely packed in a chainlike or branched structure in a cell bag. The expressions of alkaline phosphatase activity, collagen type I, and osteopontin were shown via the use of histochemical staining, immunolabeling, and confocal scanning electron microscopy. Using a numerical approach, it was found that at a given rotational speed and for a given culture medium, a larger density difference between the microcarrier and the culture medium (e.g., a modified bioactive glass particle) imparted a higher maximum shear stress on the microcarrier.
<Go to ISI>://WOS:000072925300005
A possible involvement of autophagy in amyloplast degradation in columella cells during hydrotropic response of Arabidopsis roots
Seedling roots display not only gravitropism but also hydrotropism, and the two tropisms interfere with one another. In Arabidopsis (Arabidopsis thaliana) roots, amyloplasts in columella cells are rapidly degraded during the hydrotropic response. Degradation of amyloplasts involved in gravisensing enhances the hydrotropic response by reducing the gravitropic response. However, the mechanism by which amyloplasts are degraded in hydrotropically responding roots remains unknown. In this study, the mechanistic aspects of the degradation of amyloplasts in columella cells during hydrotropic response were investigated by analyzing organellar morphology, cell polarity and changes in gene expression. The results showed that hydrotropic stimulation or systemic water stress caused dramatic changes in organellar form and positioning in columella cells. Specifically, the columella cells of hydrotropically responding or water-stressed roots lost polarity in the distribution of the endoplasmic reticulum (ER), and showed accelerated vacuolization and nuclear movement. Analysis of ER-localized GFP showed that ER redistributed around the developed vacuoles. Cells often showed decomposing amyloplasts in autophagosome-like structures. Both hydrotropic stimulation and water stress upregulated the expression of AtATG18a, which is required for autophagosome formation. Furthermore, analysis with GFP-AtATG8a revealed that both hydrotropic stimulation and water stress induced the formation of autophagosomes in the columella cells. In addition, expression of plastid marker, pt-GFP, in the columella cells dramatically decreased in response to both hydrotropic stimulation and water stress, but its decrease was much less in the autophagy mutant atg5. These results suggest that hydrotropic stimulation confers water stress in the roots, which triggers an autophagic response responsible for the degradation of amyloplasts in columella cells of Arabidopsis roots.
We have analyzed the biology of embryonic, epidermal growth factor-responsive murine neural precursor cells cultured in the high-aspect ratio vessel (HARV). Within 2-3 d of rotary-cell culture, such cells formed multiple, macroscopic, three-dimensional structures that were orders of magnitude larger than the cellular clusters ("neurospheres") formed by these cells in conventional stationary-flask cultures. Each HARV structure was composed of a multilayered cellular shell surrounding one or more central cavities that were bordered by pyknotic cell nuclei. Although the cells in the HARV structures were more pleomorphic than those in neurospheres, the structures did not appear to represent primitive neural tumors: the formation of HARV structures by precursor cells was not an irreversible phenotypic change, and the structures dill not originate front the clonal expansion of single-progenitor cells; the growth rate and invasiveness of the cells in HARVs were less than those in flasks; and HARV-cultured cells did not form tumors after subcutaneous inoculation into the Hanks of NOD-scid/scid mice. Immunohistochemical analysis suggested that HARV structures might be novel "proto-tissues" characterized by a crude. but organized, architecture, with a surface laver of immature proliferating cells (nestin- and proliferating cell nuclear antigen-positive) that enclosed strata of more differentiated cells (beta -tubulin III- and glial fibrillary acidic protein-positive) within. Rotary-cell culture may have significant implications for the eventual utility. of neural precursors for clinical neurotransplantation.
<Go to ISI>://WOS:000168690900004
Enhanced neurotrophin synthesis and molecular differentiation in non-transformed human retinal progenitor cells cultured in a rotating bioreactor
One approach to the treatment of retinal diseases, such as retinitis pigmentosa, is to replace diseased or degenerating cells with healthy cells. Even if all of the problems associated with tissue transplant were to be resolved, the availability of tissue would remain an ongoing problem. We have previously shown that transformed human retinal cells can be grown in a NASA-developed horizontally rotating culture vessel (bioreactor) to form three-dimensional-like structures with the expression of several retinal specific proteins. In this study, we have investigated growth of non-transformed human retinal progenitors (retinal stem cells) in a rotating bioreactor. This rotating culture vessel promotes cell-cell interaction between similar and dissimilar cells. We cultured retinal progenitors (Ret 1-4) alone or as a co-culture with human retinal pigment epithelial cells (RPE, D407) in this system to determine if 3D structures can be generated from non-transformed progenitors. Our second goal was to determine if the formation of 3D structures correlates with the upregulation of neurotrophins, basic fibroblast growth factor (bFGF), transforming growth factor alpha (TGFa), ciliary neurotrophic factor (CNTF), and brain-delivered neurotrophic factor (BDNF). These factors have been implicated in progenitor cell proliferation, commitment, differentiation, and survival. We also investigated the expression of the following retinal specific proteins in this system: neuron specific enolase (NSE); tyrosine hydroxylase (TH); D2D3, D-4 receptors; protein kinase-C alpha (PKC alpha), and calbindin. The 3D structures generated were characterized by phase and scanning transmission electron microscopy. Retinal progenitors, cultured alone or as a co-culture in the rotating bioreactor, formed 3D structures with some degree of differentiation, accompanied by the upregulation of bFGF, CNTF, and TGFa. Brain-derived neurotrophic factor, which is expressed ill vivo in RPE (D407), was not expressed in monolayer cultures of RPE but expressed in the rotating bioreactor-cultured RPE and retinal progenitors (Ret 1-4). Upregulation of neurotrophins was noted in all rotating bioreactor-cultured cells. Also, upregulation of D-4 receptor, calbindin, and PKC alpha was noted in the rotating bioreactor-cultured cells. We conclude that non-transformed retinal progenitors can be grown in the rotating bioreactor to form 3D structures with some degree of differentiation. We relied on molecular and biochemical analysis to characterize differentiation in cells grown in the rotating bioreactor.
<Go to ISI>://WOS:000235844900015