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R C JOHNSON

Publications and source records attributed to R C JOHNSON.

At least 19 recordsLinked to original sources
PubMed1964

5-FLUOROURACIL AS A SELECTIVE AGENT FOR GROWTH OF LEPTOSPIRAE.

Johnson, Russell C. (University of Minnesota, Minneapolis), and Palmer Rogers. 5-Fluorouracil as a selective agent for growth of leptospirae. J. Bacteriol. 87:422-426. 1964.-The use of 5-fluorouracil (FU) as a selective agent for the growth of leptospirae was investigated. Both the growth rate and the final cell yield of Leptospira pomona were unaltered with FU added to the medium at concentrations varying from 50 to 1,000 mug/ml. Growth of this organism was initiated with as few as five organisms per ml in the FU medium. With C(14)-FU, it was demonstrated that FU was not incorporated into L. pomona nucleic acids. Other leptospirae tested grew normally in the presence of FU. By use of the FU medium, L. canicola was successfully isolated from contaminated urine of experimentally infected dogs. Also, contaminated cultures of leptospirae were purified by passage through the FU medium.

Animals↗
PubMed1964

DIFFERENTIATION OF PATHOGENIC AND SAPROPHYTIC LEPTOSPIRES WITH 8-AZAGUANINE.

Johnson, Russell C. (University of Minnesota, Minneapolis), and Palmer Rogers. Differentiation of pathogenic and saprophytic leptospires with 8-azaguanine. J. Bacteriol. 88:1618-1623. 1964.-The use of the purine analogue, 8-azaguanine, as a differential agent for the separation of pathogenic and saprophytic leptospires was investigated. Growth of strains of the saprophyte Leptospira biflexa was almost insensitive to the bacteriostatic action of 8-azaguanine at concentrations varying from 25 to 600 mug/ml; these saprophytic leptospires were serially transferred five times in media containing 225 mug without any change in growth rate or cell yield. In contrast, decreased growth rate and cell yield of the pathogenic serotypes were observed with 25 to 50 mug/ml of 8-azaguanine. Complete inhibition of growth occurred at concentrations of 100 mug/ml and above. A medium containing 225 mug/ml of 8-azaguanine was successfully used to differentiate 20 serotypes of pathogenic leptospires and 10 saprophytic strains. L. andaman CH11, L. semarang Veldrat S1 73, and L. andaman Correa, were classified with the L. biflexa strains on the basis of their growth response to 8-azaguanine.

Antimetabolites↗
PubMed1963

NUTRITION OF LEPTOSPIRA POMONA. II. FATTY ACID REQUIREMENTS.

Johnson, R. C. (Fort Detrick, Frederick, Md.) and N. D. Gary. Nutrition of Leptospira pomona. II. Fatty acid requirements. J. Bacteriol. 85:976-982. 1963.-The albumin fraction of rabbit serum, obtained by (NH(4))(2)SO(4) fractionation, supported good growth of Leptospira pomona Wickard when added to a medium containing phosphate buffer, NH(4)Cl, and thiamine. Extraction of the albumin fraction with ethanol and ether (3:1) resulted in a loss of its growth-supporting activity, which could be restored upon the addition of the extract or various fatty acids. The growth-supporting activity of fatty acids containing 2 to 18 carbon atoms was investigated with the extracted albumin medium. The activity of the fatty acid was found to be related to the number of carbon atoms in the molecule. Maximal growth was obtained with palmitic, heptadecanoic, stearic, and oleic acids. The amount of growth of L. pomona increased at a fixed concentration of albumin as the molecular ratio of extracted albumin to the long-chain fatty acids increased from 1:1 to 1:6. At higher ratios, growth decreased sharply. Direct utilization of fatty acids during growth of L. pomona was shown by the incorporation of palmitic acid-1-C(14) or -2-C(14) into cellular material. A medium composed of 0.02 m Na(2)HPO(4)-KH(2)PO(4) buffer (pH 7.4), 0.8% extracted albumin, 4 x 10(-4)m palmitic acid, 10(-3)m NH(4)Cl, and 5 mug/ml of thiamine supported good growth. L. pomona was transferred ten times, and seven other serotypes were transferred five times, in this medium without any decrease in the amount of growth. Growth of L. pomona was initiated with approximately four organisms per ml.

Ammonium Chloride↗
PubMed1963

NUTRITION OF LEPTOSPIRA POMONA. III. CALCIUM, MAGNESIUM, AND POTASSIUM REQUIREMENTS.

Johnson, R. C. (Fort Detrick, Frederick, Md.) and N. D. Gary. Nutrition of Leptospira pomona. III. Calcium, magnesium, and potassium requirements. J. Bacteriol. 85:983-985. 1963.-The cation requirements for Leptospira pomona Wickard were investigated employing a basal medium prepared with 10% deionized rabbit serum and containing 10(-3)m NH(4)Cl, 5 mug/ml thiamine, and 0.01 m Na(2)HPO(4) buffer (pH 7.4). Rabbit serum was deionized by passage through a column of Amberlite IRC-50 resin. This basal medium did not support growth when either Ca(++) or Mg(++) was added to it. However, when both Ca(++) (3 x 10(-5)m) and Mg(++) (5 x 10(-6)m) were present, growth was obtained. Although an absolute requirement for K(+) could not be demonstrated, an increase in the amount of growth did occur if K(+) (5 x 10(-5)m) was incorporated in addition to Ca(++) and Mg(++). When adequate concentrations of Ca(++) and K(+) were present with a limiting concentration of Mg(++) (less than 5 x 10(-7)m), filamentous cells were observed.

Animals↗