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Biomedical subjects

G R Smith

Publications and source records attributed to G R Smith.

At least 343 records · Page 19Linked to original sources
PubMed1975

Human volunteer and anthropomorphic dummy tests of driver air cushion system.

The dynamic impact tests at Southwest Research Institute for the first time exposed human volunteers to production-like driver air cushion system depolyments at impact levels equivalent to a 30 mph barrier crash (48 kph). No significant injury was produced. At no time was it necessary for the secondary restraint systems to be utilized and the entire program schedule was carried out as planned. All tests were conducted under the most safe and controlled conditions possible, and typify only what the air cushions might accomplish in direct, head-on impacts up to 30 mph (48 kph). In comparing the test results, the anthropomorphic dummies' response to impact was conservative compared to the human volunteers. These and other human volunteer tests were run to help understand what might be expected in real world driving conditions. To further understand the value of this new safety system, 1000 1973 Chevrolets were built and places in a high mileage fleet across the couhtry. They now have accumulated 41 millions miles of experience and have had 15 accidents of sufficient severity that the air cushion depolyed. This fleet was followed with 1974 vehicles with air cushions sold to the general public as an option. These cars, combined with the test fleet, have accumulated approximately 60 million miles and have a total of 25 depolyments with 34 occupants in the front seat. There has been one fatality in accidents involving these vehicles, a seven week old baby boy. The child was not restrained in any protective carrier. All other injuries have been classified AIS-1 except for three AIS-2. Facial injuries have been very minimal and there have been no known hearing impairments as a result of these accident situations. To date, the results have been encouraging but caution must be taken in their interpretation. The population of drivers is not to be considered normal. The 60 million miles may appear to be a large number, but only represents 25 minutes of driving time of the total U.S. car population in 1 year.

Accidents, Traffic↗
PubMed1975

The virulence of vaccine strains of Mycoplasma mycoides var. mycoides recovered from inoculated cattle.

The T1 and KH3J attenuated strains of M mycoides, well-known in Africa for immunisation against contagious bovine pleuropneumonia, were recovered from the lymph nodes of cattle at intervals up to three months after vaccination. Virulence titrations in mice indicated that the organisms recovered from cattle were of no greater virulence than the strains used for inoculation. There was, therefore, no suggestion that the use of attenuated vaccines in the field might be associated with reversion to virulence after inoculation.

Animals↗
PubMed1975

Contagious bovine pleuropneumonia: mouse-protective antibody in the sera of infected and vaccinated cattle.

Cattle produced humoral mouse-protective antibody (MPA) to Mycoplasma mycoides var mycoides as a result of natural infection, hyperimmunisation, vaccination with well-known strains of living vaccines or vaccination with killed cultures. Bovine MPA was distinct from complement-fixing and precipitating antibodies and was frequently detected in their absence, particularly in the sera of vaccinated--as opposed to naturally infected--cattle. In view of its defensive role in artificially-infected mice, it seems likely that such antibody plays a part in resistance to the disease in cattle. High levels of MPA followed inoculation of cattle with killed concentrated culture containing adjuvant; this finding merits further investigation, as it may lead to improved methods of vaccination.

Animals↗
PubMed1974

Construction of phi80 dhis carrying Salmonella typhimurium histidine operon mutations.

Starting with a previously isolated F'his episome and phi80 dhis imm(lambda) cI857 transducing phage, we have constructed recombinant elements bearing previously isolated his mutations from Salmonella typhimurium. These phages were constructed as sources of deoxyribonucleic acid for in vitro biochemical experiments on gene regulation. The manipulation of genes between S. typhimurium and Escherichia coli described here may be useful in studying other S. typhimurium operons.

Alleles↗
PubMed1973

Effect of sub-lethal treatment with formalin on the germination of Aspergillus fumigatus spores.

Sub-lethal exposure of Aspergillus fumigatus spore suspensions to formalin resulted in prolongation by 1-22 days of the period of less than one day normally needed by spores to produce visible growth in Sabouraud's liquid medium at 37 degrees C.; the degree of delay depended on the concentration of formalin and the duration of exposure, and was due to an increase in the germination-time of spores. The formalin concentration could be adjusted so as to affect the germination-time of almost all spores in a suspension without reducing viability. The effect on germination was not abolished by thorough washing or treatment with sodium sulphite. The spores of four different strains of A. fumigatus and of cultures aged 3 to 14 days reacted similarly to formalin treatment. Although of greatly reduced virulence for mice, affected viable spores were still capable of producing infection and death following intravenous inoculation, provided they were not eliminated by the host before germination occurred.

Animals↗
PubMed1972

Tetraploid origin of the karyotype of catostomid fishes.

Catostomid fishes appear to have 2n(-->4n?) approximately 100 chromosomes. The Cyprinidae, from which catostomids probably diverged before the Eocene, usually have 2n = 48 or 50 chromosomes. Preliminary cytophotometric measurements indicate an approximate doubling of DNA content of cells among catostomids.

Animals↗
PubMed1972

Experimental aspergillosis in mice: aspects of resistance.

Intravenous inoculation of Aspergillus fumigatus spores was used to study experimentally induced and natural resistance. Slight resistance resulted in increased survival time and higher resistance produced in addition a decreased infection rate.Sublethal doses of living spores gave significant protection against challenge 3 weeks later, but large doses of heat-killed spores had no demonstrable effect.Mice from one source showed a single, dramatic decrease in dose response to a deep-frozen strain of the organism over a period of 34 months. The dose response initially resembled that described by Scholer (1959) in which one million spores killed the majority of mice. The change was almost certainly due to an increase in resistance of the mice due to environmental factors, and the resistance was probably also effective against other strains of the organism. Although not proved, it seemed likely that the resistance was due to increased natural contact with A. fumigatus or related fungi. Possibly for a similar reason, mice of the same stock bred on different premises differed in their susceptibility to infection. The results indicated that environmental resistance-producing factors may have been operating simultaneously on a number of premises housing laboratory animals in south-east England. These findings may have significance in relation to the occurrence of natural aspergillosis of mammals and birds.Of five A. fumigatus strains, four were of closely similar virulence; the fifth strain grew more slowly in vitro and was somewhat less virulent. Isolates from mice which died sporadically after small doses of spores were of no greater virulence than the inoculated strain. Although the susceptibility of mice aged 3 weeks was not uniform under all conditions, such animals were less resistant than young adult mice. Mice from six different sources showed only slight differences in susceptibility between each other, or from mice known to have developed a natural resistance.

Age Factors↗