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Biomedical subjects

J Hotchin

Publications and source records attributed to J Hotchin.

47 records · Page 3Linked to original sources
PubMed1968

The biological effectiveness of solar electromagnetic radiation in space.

An attempt has been made to determine the solar ultraviolet action spectrum for dried coliphage T-1 exposed to space under various filters at sounding rocket altitudes between 80 to 150 km. The survival of these microorganisms was compared with the preliminary results of laboratory ultraviolet irradiation experiments using monochromatic light sources of wavelengths of 1633 angstroms, 2062 angstroms, 2537 angstroms and of 3064 angstroms to 3200 angstroms. The results indicate that ultraviolet light of wave-lengths between 2000 angstroms to 3000 angstroms was mainly responsible for the killing of the filter protected microorganisms. More studies of the biological action spectrum of the vacuum ultraviolet light including the Lyman alpha emission are needed to determine the cause of the more than 100 fold higher death rate of the microorganisms which were not protected during the space exposure by filters.

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PubMed1968

The survival of terrestrial microorganisms in space at orbital altitudes during Gemini satellite experiments.

In a previous series of rocket- and satellite-borne experiments, microorganisms were exposed to space between altitudes of 60 to 460 km for periods between 3 minutes and 4 months. The results showed that some of the unprotected microorganisms survived the direct exposure for up to 17 hours. Complete survival was found when the microorganisms were shielded from nonpenetrating radiation. These results made it desirable to systematically study the lethal influence of the space environment on a wider spectrum of unprotected microorganisms over various exposure periods. This communication presents the results of exposure experiments on board the Gemini XII satellite. The microorganisms were dried on plastic coated aluminum plates using techniques which will be described elsewhere. During the flight of the Gemini XII space capsule, the microorganisms were directly exposed to space for approximately 6 1/2 hours. After the successful completion of the Gemini XII mission the payload was returned to the laboratory for elution and titration of the microorganisms using techniques described elsewhere. The results showed that again survival of some microorganisms had occurred. An attempt is made to integrate these results with data obtained in previously published experiments.

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PubMed1967

Slow virus kidney disease of mice.

Preliminary observations based on organ weight differential, renal function, and glomerular lesions in mice infected neonatally with lymphocytic choriomeningitis indicate the presence of a slow virus-induced kidney disease of mice. This condition is accompanied by a marked decrease in the size of the kidneys, with progressive diminution of renal function, as shown by measurements of creatinine and urea clearance.

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PubMed1967

The survival of micro-organisms in space. Further rocket and balloon-borne exposure experiments.

This report describes the results of survival studies of terrestrial micro-organisms exposed directly to the space environment on two balloons and in two rocket flights. The work is part of a program to develop techniques for the collection of micro-organisms in the size range of micrometeorite particles in space or non-terrestrial atmospheres, and their return to earth in a viable state for further study. Previous survival studies were reported (J. Hotchin, P. Lorenz and C. Hemenway, Nature 206 (1965) 442) in which a few relatively large area samples of micro-organisms were exposed on millipore filter cemented to aluminum plates. In the present series of experiments, newly developed techniques have resulted in a 25-fold miniaturization resulting in a corresponding increase in the number of experiments performed. This has enabled a statistical evaluation of the results to be made. A total of 756 separate exposure units (each approximately 5 x 5 mm in size) were flown in four experiments, and organisms used were coliphage T1, penicillium roqueforti (THOM) mold spores, poliovirus type I (Pfizer attenuated Sabin vaccine strain), and bacillus subtilis spores. The organisms were deposited either by spraying directly upon the vinyl-coated metal units, or by droplet seeding into shallow depressions in the millipore filter membrane-coated units. Groups of units were prepared comprising fully exposed, inverted (screened by 2 mm of Al), and filter-protected organisms. All of these were included in the flight set, the back up set, and a laboratory control set. The altitude of the exposures varied from 35 km in the balloon experiments to 150 km in the rocket experiments. Times of exposures at altitude were approximately 6 hours for the balloon flights and about 3 minutes for the rocket experiments.

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