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Biomedical subjects

R J Ball

Publications and source records attributed to R J Ball.

At least 37 records · Page 2Linked to original sources
PubMed1968

Mortality of altitude-exposed mice infected with Pasteurella tularensis.

The influence of reduced barometric pressure equivalent to an altitude of 18,000 ft (5,486 m) on the susceptibility of mice to tularemia was investigated by exposing groups of animals to the test environment before, after, or before and after intraperitoneal inoculation of 225 colony-forming units of Pasteurella tularensis. Similarly infected control animals were not exposed to the experimental environment. Two measurements of mortality were employed: (i) the day on which 50% of the mice were dead; and (ii) the number of dead mice on the 8th day. Continuous altitude exposure for 14 days prior to infection had no effect on host susceptibility but exposure after infection significantly increased mortality (P < 0.001).

Altitude↗
PubMed1967

Effect of high oxygen concentration on virulence of Staphylococcus aureus.

Cultures of Staphylococcus aureus were agitated and treated with oxygen or air for a period of 29 days. At intervals of 1, 3, 9, 15, and 29 days, samples of washed cells were tested for coagulase activity and for abscess-producing ability. It was found that aeration with agitation initially increased abscess formation and that the increase was of the same magnitude for oxygen and air. Continued treatment beyond 1 day resulted in a progressive decrease in this activity which was more pronounced in the oxygenated cultures. Throughout the treatment, the bound coagulase activity remained constant. Thus, there appeared to be no quantitative relationship of coagulase titer with virulence as expressed by lesion formation.

Bacteriological Techniques↗
PubMed1967

Effect of environment on staphylococcal lesions in mice.

The influence of reduced barometric pressure on the development and healing of staphylococcal skin lesions in mice was investigated by exposing groups of animals to the test environment before, after, or before and after subcutaneous inoculation with 3.5 x 10 colony-forming units of a phage type 80 strain of Staphylococcus aureus. Similarly infected control animals were not exposed to the experimental environment. The results indicate that the lesions which developed in mice exposed to the test environment prior to infectious challenge were larger and healed at a slower rate than those in mice maintained at ground level before infection. Exposure after inoculation produced no demonstrable effect in the size or healing rate of the experimental lesions.

Journal Article↗
PubMed1966

Improved motility medium.

An improved motility medium which permits additional cultural characterization is described. Advantages include maximal motility due to a change in the physical state of the medium from solid to liquid at incubation temperatures, a definitive stab line, preservation of the stab line with nonmotile organisms, and visual delineation of culture motility. In addition, nitrate reduction, nitrogen gas production, and gelatin liquefaction may be demonstrated.

Culture Media↗
PubMed1966

Comparison of acetate differential agar with sellers citrate-mannitol-agar.

A total of 245 isolates of Escherichia coli (paracolons) were employed in comparing the use of acetate differential agar (ADA) with the simple test described by Sellers to eliminate these organisms from consideration as enteric pathogens. At 18 hr after the media were inoculated, 83% of the isolates produced a positive citrate reaction on Sellers citrate-mannitol-agar (SCM) and 7% gave a positive reaction on ADA. At 24 hr, 92% of the cultures were positive on SCM versus 42% on ADA. At 48 hr, 244 (99.6%) of the isolates were positive on SCM, whereas a 72-hr incubation period was required for equal results with ADA. One isolate failed to grow on either medium.

Journal Article↗