Biomedical subjects

E Schopper

Publications and source records attributed to E Schopper.

15 recordsLinked to original sources

PubMed1994

Recent results of the joint ESA-DARA/IBMP experiments Biokosmos "Seeds".

Comparison of experimental data obtained from short (SDEF) and long duration exposure flights (LDEF) have recently led to results which will be significant for longer and/or repeated sojourn of man in space. Under orbital conditions biological stress and damage are induced in test subjects by cosmic radiation, especially the high energetic, densely ionizing component of heavy ions. Plant seeds were successful model systems for a biotest in studying the physiological damages and mutagenic effect caused by ionizing cosmic radiation in particular stem cells. Dosimetrically, the subdivision into charge- and Let-groups reveals the contribution of the intermediate group (LET = 350-1000 MeV/cm) due to the medium heavy ions (Z = 6-10). Their relative contribution increases with the lower inclination of the orbit of LDEF-1; on the other hand, the total fluence becomes higher with longer duration of the flight. The observed endpoints of the biological radiation damage hint at a correlation with particle dose rate rather than with the dose; additionally, data on shielding effects inside and outside the space craft and its exposure were gained from the different SDEF- and LDEF-missions.

Arabidopsis↗

PubMed1994

Biophysical effect of cosmic heavy ions of distinct LET-classes in a plant model system.

Results presented from recent space flight BION 9 show biological effects of different LET-classes of HZE-particles in different target regions of the seed (meristem and the whole embryo) of Arabidopsis thaliana (L.) Heyhn. HZE-one hit events and non-hit events, i.e. only hit by the low-LET background radiation, and their combined effects on the biological damage endpoint lethality are distinguished. This procedure is opening the opportunity of an approach to comparative studies of the biological effects induced by cosmic HZE-particles of different LET-ranges interacting in the complex cosmic radiation spectrum and with other space flight conditions.

Arabidopsis↗

PubMed1992

Structure of heavy ion tracks in Ag-Cl detectors.

The microdosimetric lateral structure of tracks of charged nuclear particles in monocrystalline layers of AgCl-detectors has been measured by means of a videoelectronic computer-controlled image analysing system. The lateral optical density profiles, recorded along the track in sequential steps of 0.2 micrometer show compact tracks with a density maximum around the track axis as well as "coreless" tracks with a density minimum towards the axis. This minimum is more pronounced for particles of high effective charge mean q exceeding approximately 25. The effect of fading of the core depends on the charge state mean q of the particle rather than on its (high) LET. This finding points towards an increased atomic displacement by Coulomb-repulsion into the lattice of the detector of Ag(+)-atoms which are needed for the formation of the track. Examples of measurements and of tracks are presented.

Crystallization↗

PubMed1992

Experiment "Seeds" on Biokosmos 9. Dosimetric part.

The aim of the experiment "Seeds" on the Sowjetic satellite Biokosmos 9 was the observation of mutagenic effects caused at special loci of seeds of Arabidopsis thaliana and assigned to particles of the Cosmic radiation. Two types of exposure units were flown: A low-shielding unit Type I, mounted at the surface of the satellite (1.4 g/cm2 shielding) and, for comparison, an identical item inside (16 g/cm2 shielding), using nuclear emulsion as track detectors. A Type II unit, flown inside (18g/cm2 shielding) was mounted with AgCl track detectors. The layout will be briefly described. A first set of dosimetric data from the physical evaluation of the experiment will be presented. The subdivision into charge- and LET-groups shows a rather high contribution of the intermediate LET-group (350-1000 MeV/cm) due to medium heavy particles (Z = 6-10) and to enders of light (p, alpha) particles.

Arabidopsis↗

PubMed1992

Cosmic ray LET spectra and doses on board Cosmos-2044 biosatellite.

Results of the experiments on board Cosmos-2044 (Biosatellite 9) are presented. Various nuclear track detectors (NTD) (dielectric, AgCl-based, nuclear emulsions) were used to obtain the LET spectra inside and outside the satellite. The spectra from the different NTDs have proved to be in general agreement. The results of LET spectra calculations using two different models are also presented. The resultant LET distributions are used to calculate the absorbed and equivalent doses and the orbit-averaged quality factors (QF) of the cosmic rays (CR). Absorbed dose rates inside (approximately 20 g cm-2 shielding) and outside (1 g cm-2) the spacecraft, omitting electrons, were found to be 4.8 and 8.6 mrad d-1, respectively, while the corresponding equivalent doses were 8.8 and 19.7 mrem d-1. The effects of the flight parameters on the total fluence of, and on the dose from, the CR particles are analyzed. Integral dose distributions of the detected particles are also determined. The LET values which separate absorbed and equivalent doses into 50% intervals are estimated. The CR-39 dielectric NTD is shown to detect 20-30% of the absorbed dose and 60-70% of the equivalent dose in the Cosmos-2044 orbit. The influence of solar activity phase on the magnitude of CR flux is discussed.

Cosmic Radiation↗

PubMed1990

Biokosmos 8 experiment: dosimetric measurements with AgCl track detectors behind low shielding.

Monocrystalline sheets of AgCl nuclear track detectors, mounted on top of a detector package, covered by a thin light-filter of 15 micrometers-thick Kapton-foil, were flown in the outside facilities of the Biokosmos 8 Mission. The aim of this lay-out was to record low energy protons and heavy ions, including SAA particles, from the unshielded cosmic radiation. The tracks recorded turned out to be strongly faded. The possible reasons, high temperature (>60 degrees C at the detector surface indicated by temperature markers) or too high temporary intensities of the filtered sunlight, are discussed on the basis of simulation experiments. The report briefly describes: (1) Characteristics of the AgCl-detectors. (2) The lay-out of the experiment, postflight handling and results. (3) Simulation experiments on the ground with respect to the observed fading. (4) A new lay-out proposed for a future analogous experiment with AgCl-detectors.

Atlantic Ocean↗

PubMed1986

Dosimetric mapping inside BIORACK.

The experiment was flown in different locations inside BIORACK on the D1 mission. It contained different plastic detectors (cellulose nitrate, Lexan, and CR 39) and emulsions to measure the high LET components of the radiation environment. For low LET measurements thermoluminescence dosimeters (LiF) were used. The paper gives data about total dose, charge, energy, and LET spectra so far obtained. These data are compared with data of previous spaceflights.

Cosmic Radiation↗

PubMed1986

Microscopic track structure of heavy ions videoelectronically measured.

The track of an ionizing particle in a track detector, such as silver-chloride or nuclear emulsion, contains two measurable parameters, the "track width"--which corresponds to the integrated lateral energy deposition dE/dtau(x,r) over r along dx (dE/dx or LET)--and the lateral distribution of the track density along r, the radial structure of the track. A videoelectronic device consisting of a computer-controlled microscope, developed in Frankfurt, automatically reads out consecutive lateral profiles of the optical density of a preset track, following it through the depth of the detector. For a given track length (100 microns, 400 profiles for instance) the system evaluates the mean track width MTW and the variance sigma 2 . Both quantities are correlated so that a given MTW (LET) belongs to different values of sigma 2 depending on the charge of the particle. Videosystem and results are presented.

Heavy Ions↗

PubMed1984

Radiation measurements aboard Spacelab 1.

The radiation environment inside Spacelab 1 was measured by a set of passive radiation detectors distributed throughout the volume inside the module, in the access tunnel, and outside on the pallet. Measurements of the low-LET (linear energy transfer) component obtained from the thermoluminescence detectors ranged from 102 to 190 millirads, yielding an average low-LET dose rate of 11.2 millirads per day inside the module, about twice the low-LET dose rate measured on previous flights of the space shuttle. Because of the higher inclination of the orbit (57 degrees versus 28.5 degrees for previous shuttle flights), substantial fluxes of highly ionizing HZE particles (high charge and energy galactic cosmic rays were observed, yielding an overall average mission dose-equivalent of about 150 millirems, more than three times higher than measured on previous shuttle missions.

Cosmic Radiation↗

PubMed1984

Advanced biostack: experiment 1 ES 027 on Spacelab-1.

The radiobiological properties of the heavy ions of cosmic radiation were investigated on Spacelab 1 by use of biostacks, monolayers of biological test organisms sandwiched between thin foils of different types of nuclear track detectors. Biostacks were exposed to cosmic radiation at several locations with different shielding environments in the module and on the pallet. Evaluations of the physical and biological components of the experiment to date indicate that in general they survived the spaceflight in good condition. Dosimetric data are presented for the different shielding environments.

Animals↗

PubMed1977

Assignment of particle tracks to spores of Bacillus subtilis on silver chloride detectors.

In Biostack III B, flown in the Apollo-Soyuz Test Project, AgCl detectors were used to study ionizing effects of HZE particles on spores of Bacillus subtilis or eggs of Artemia salina. The tracks of these particles inside the detectors are used to extrapolate the path of the particle near the biological objects which are fixed at the detector surface. The closest distance to the geometric centre of the object, the so-called impact parameter, is determined with a mean accuracy of 0.3 micrometers for 1 micrometers spores. From knowledge of the lateral distribution of the energy transferred by primary and secondary ionization effects of the particle, the energy deposit and its localization at the objects can be determined. We describe some technical aspects of a video-electronic scanning system, Quantimet 720, which has been adjusted to the particular requirements of these experiments. The main improvements achieved are increased precision of coordinate measurements, objective focusing of the microscopic image combined with measurements of the density profile of particle tracks, and finally speeding up of the measurements by automatic data transfer.

Animals↗

PubMed1975

Radiobiological results of the Biostack experiment on board Apollo 16 and 17.

After penetrating the Biostack capsule, some of the HZE particles hit the biological objects carried: bacterial spores (Bacillus subtilis), seeds (Arabidopsis thaliana and Vicia faba), and shrimp eggs (Artemia salina). The different biological objects were affected by heavy ions in widely varying ways. A broad range of radiobiological investigations has been carried out in regard to the objects' response to HZE particles. The most sensitive biological objects in the Biostack experiments proved to be the shrimp eggs. The development of 500 eggs hit by heavy cosmic ions was investigated. This differed significantly from the flight controls (eggs flown in the Biostack but not hit by heavy ions) and from the ground controls. From this it has been concluded that penetration on the part of a single heavy ion may injure the encysted blastula. This damage was found to influence gastrula formation and even the hatching process of the nauplius. Abnormalities (increased by a factor of 10) in the orthonauplius were observed during the development of the hit eggs; they consisted, for example, of shortened extremities or an abnormal thorax or abdomen. In addition, eggs of Tribolium confusum and Carausius morosus, which were included in Biostack 2 (Apollo 17), have been investigated, and the influence of single heavy ions on the development process of these highly organized insects has been studied.

Abnormalities, Radiation-Induced↗

PubMed1974

AgCl detectors in the Biostack II experiment aboard Apollo 17.

Two layers of AgCl detectors with a total surface of 90 cm2 were flown. Tracks of nuclei, from light (Z>4) up to the heaviest were recorded and could be distinguished by their geometrical trackwidths. The tracks were divided into five groups of atomic numbers, and their abundance was measured. Also the number of surviving nuclear stars was counted. 22.5 cm2 of the detector surface were covered with eggs of Artemia salina. The detectors could be developed without removing the eggs, so that the spots hit could be determined directly. The radiation effect on these eggs is being investigated.

Animals↗

PubMed1973

The Biostack experiment on Apollo 16.

The object of the Biostack experiment is to study the biological effects of high ZE particles of cosmic radiation in order to obtain information on the mechanism of these particles in biological matter. For this purpose individual local evaluation methods have been developed which allow one to identify each biologically effective particle and to correlate the individual hitting particle with the biological effect produced. The Biostack experimental package contains a series of monolayers of selected biological objects (Bacillus subtilis spores, Arabidopsis thaliana seeds, Vicia faba radiculae, Artemia salina eggs) with each layer sandwiched between several different cosmic ion track detectors (nuclear emulsions, cellulose nitrate, polycarbonate). By this arrangement a variety of biological effects due to a single penetrating particle can be analysed. Influence on cellular and tissue development, nuclear damages, and mutation induction are the main investigated effects. These space flight findings will be completed by results of balloon flight and accelerator experiments.

Animals↗

PubMed1973

Solid state AgCl detectors for nuclear tracks with on- and off-response at choice: applications to life sciences.

A new concept of trackforming solid state detectors is presented. These detectors record and accumulate tracks of ionizing particles which can be revealed if they are irradiated with yellow light during the passage of the particle through the detector; otherwise the tracks are dropped by fading. Tracks stabilized by yellow light are stable for months. The detectors consist of thin layers of 200-300 micrometers of Cd-doped AgCl crystals, supported by a thin plate of quartz glass. The invisible latent tracks in these detectors are revealed at microscopically visible size by ultraviolet light. The sensitivity of the crystals against particles of different specific energy transfer depends upon the concentration of Cd; these have rather good thresholds, which permit selective recording in a well-known manner. These AgCl(Cd) crystals have a unique property amongst trackforming detectors; their response can be switched on and off at choice, for instance by electronic triggering of the stabilizing accompanying yellow light. This allows a time assignment of particle tracks, or restriction to tracks of desired particles. Examples of tracks and of applications in cosmic ray research, heavy ion physics, radiobiology and dosimetry are given.

Bacillus subtilis↗