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Biomedical subjects

G Reitz

Publications and source records attributed to G Reitz.

65 records · Page 4Linked to original sources
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↗
PubMed1983

Indomethacin improvement of septic acute respiratory failure in a porcine model.

The effects of indomethacin, a prostaglandin synthesis blocker, were tested in a porcine model of septic acute respiratory failure (ARF) produced by continuous infusion of live Ps. aeruginosa. Control groups received either indomethacin boluses (2 mg/kg) intravenously at 20 and 210 minutes or Ps. aeruginosa infusion (2 X 10(8) CFU/20 kg/min). The treatment group received both continuous Ps. aeruginosa infusion and indomethacin. Indomethacin alone transiently but significantly decreased cardiac indices, heart rate, and PaCO2. With Ps. aeruginosa infusion, significant pulmonary hypertension, hypoxemia, increased intrapulmonary shunt fraction, and systemic hypotension occurred. In this porcine model of septic ARF, indomethacin doubled the survival period and improved cardiopulmonary parameters.

Acute Disease↗
PubMed1979

Dosimetric and biological results from the Bacillus subtilis Biostack experiment with the Apollo-Soyuz Test Project.

The evaluation of the Bacillus subtilis experiment has been completed. The biological and the physical results for this part of the Apollo-Soyuz Test Project (ASTP) Biostack experiment are given. This comprises dosimetric data for the cosmic radiation at that orbit as well as biological findings from two types of plastic detectors. Further, the frequency distributions of the physical quantities atomic number, energy and energy loss of the heavy ions within the sample of spores hit are presented. The biological hazard presented by cosmic HZE-particles has been much underestimated.

Bacillus subtilis↗
PubMed1978

Radiobiological results from the Bacillus subtilis Biostack experiments within the Apollo and the ASTP space flights.

In order to check the results of earlier Biostack experiments, new experimental techniques were developed for the Biostack III experiment in the Apollo-Soyuz test project (ASTP). These techniques resulted in an increased accuracy of localization down to 0.2 micrometers for the determination of the impact parameter, accompanied by an increase in the sample size available for biological investigation. In addition, colony forming ability, metabolic mutations, and mutations affecting UV- and x-ray sensitivity were rendered observable by these methods. The biological and physical results obtained so far from the evaluation of the Bacillus subtilis experiment within Biostack III confirm and extend the findings of the previous Biostack experiments. They also add to the questions about the mechanisms of action of the radiation field under investigation, since the observed effects cannot be interpreted in terms of standard concepts.

Bacillus subtilis↗
PubMed1976

Effect of space factors on Escherichia coli B/r cells.

Stationary phase cells of Escherichia coli B/r were inactivated when they were exposed to high vacuum (10(-6) torr). About 5% of the cells were still able to form a colony after 45 min exposure. Vacuum dried cells (0.5 torr, 120 min) show colony forming ability of 30% or more. They were inactivated to about 5% by further vacuum treatment. Vacuum treated cells showed higher permeability for various cell components. UV irradiated E. coli B/r cells in vacuum showed increased UV sensitivity. DNA-protein cross-links were preferentially formed in a vacuum. To obtain 63% of DNA cross linked with protein required 852 erg mm-2 (D37) of UV irradiation in suspension and only 72 erg mm-2 of UV irradiation in vacuum. The protein components of DNA-protein cross-links were hydrolysed with pronase E and the amino acids directly bonding to DNA were determined. The most important amino acids concerned in DNA-protein cross-links seem to be glycine and alanine, followed by aspartic acid (asparagine), glutamic acid (glutamine) and histidine. The sensitivity to X-rays of stationary phase E. coli B/r cells seems to depend on the remaining gas atmospheric in the vacuum since it varies with different pumping systems.

Amino Acids↗
PubMed1976

Localization and track evaluation of HZE particles.

A new method of track-etching was developed called "individual etching", allowing increased accuracy of the localization whereby a latent track is developed under microscopic control. The influence of the humidity of the detectors at the beginning of the etch process was investigated. This influence consists in an increase of bulk and track etching rate. The scattering in experimental data, which is mostly attributed to the inhomogeneity of the material, can be partially explained by this effect, especially the difference in isotopic resolution between accelerator experiments and cosmic-ray flights.

Bacillus subtilis↗
PubMedDate not supplied

Dosimetric measurements in manned missions.

Detector packages consisting of thermoluminescence detectors (TLDs), nuclear emulsions and plastic nuclear track detectors were exposed in different sections of the MIR space station, inside the Spacelab during the IML1 mission, and inside Spacelab module and tunnel during the D2 mission. This report concentrates on total dose measurements with TLDs during these mission. The results are discussed and compared to results of former missions and to calculations. Finally, dose equivalents and mean quality factors for each mission are presented which are derived from the TLD results and results obtained from the other detector systems. Dose equivalents range between 200 microSvd-1 and 700 microSvd-1.

Aerospace Medicine↗
PubMedDate not supplied

Critical issues in connection with human planetary missions: protection of and from the environment.

Activities associated with human missions to the Moon or to Mars will interact with the environment in two reciprocal ways: (i) the mission needs to be protected from the natural environmental elements that can be harmful to human health, the equipment or to their operations: (ii) the specific natural environment of the Moon or Mars should be protected so that it retains its value for scientific and other purposes. The following environmental elements need to be considered in order to protect humans and the equipment on the planetary surface: (i) cosmic ionizing radiation, (ii) solar particle events; (iii) solar ultraviolet radiation; (iv) reduced gravity; (v) thin atmosphere; (vi) extremes in temperatures and their fluctuations; (vii) surface dust; (viii) impacts by meteorites and micrometeorites. In order to protect the planetary environment. the requirements for planetary protection as adopted by COSPAR for lander missions need to be revised in view of human presence on the planet. Landers carrying equipment for exobiological investigations require special consideration to reduce contamination by terrestrial microorganisms and organic matter to the Greatest feasible extent. Records of human activities on the planet's surface should be maintained in sufficient detail that future scientific experimenters can determine whether environmental modifications have resulted from explorations. Grant numbers: 14056/99/NL/PA.

Aerospace Medicine↗
PubMedDate not supplied

Measurements of radiation exposure in civil aircraft.

The radiation exposures on 12 flights of German airlines were measured with an active dosemeter based on two silicon semiconductors. The dependence on the date, altitude and route of the flights was studied. Measured dose rates and preliminary dose equivalent rates of the individual flights are given and compared with model calculations.

Aerospace Medicine↗