C. P. Miller

Effect of bacterial endotoxins on carbohydrate metabolism of rabbits.

Summary The intravenous injection of meningococcal or Salmonella endotoxin into rabbits produced increase in blood glucose, lactic acid and inorganic phosphorus. This was followed by hypoglycemia which could be observed before the death of the animal. Liver and muscle glycogen decreased while lactic acid content of the tissues increased. The pyruvic acid content of blood and tissues showed a significant decrease. Succinic dehydrogenase in both muscle and liver was markedly inhibited. Cytochrome oxidase activity was not affected.

Clearance of bacteria from the blood of irradiated rabbits.

Summary Normal and irradiated rabbits were inoculated intravenously with approximately 106 Klebsiella pneumoniae, Type A. At intervals thereafter plate counts were made on peripheral blood. During the first 4 hours after inoculation the rate of clearance of microorganisms from the blood stream was as rapid and almost as complete in rabbits which had been exposed 1-8 days before with 800 r total body x-irradiation (LD50/30) as in unirradiated controls. From the 8th hour on, in most of the rabbits 3-8 days post-irradiation, the colony counts increased steadily until the animals died. These findings indicate that in the irradiated rabbit the reticulo-endo-thelial system was able for a few hours to remove the bacteria from the circulating blood but was unable to retain and destroy them.

Studies on the Action of Penicillin. IV. Development of Penicillin Resistance by Gonococcus.

Summary Penicillin-fastness developed most rapidly in gonococci under conditions which permitted the greatest number of viable microorganisms to be transferred to a higher concentration of penicillin at each transfer. One strain of gonococcus acquired the ability to prow on media containing 21 units per ml. So appreciable increase in penicillin tolerance resulted from repeated exposure to bacteriostatic concentrations of penicillin.

Studies on Action of Penicillin. V. Virulence of Penicillin Resistant Strains of Meningococcus.

Summary The antibody response of swine to formolized swine influenza virus adsorbed on alum is essentially the same as that to the vaccine dispersed in saline solution. The chief influence of the alum is a brief delay in the peak response. The higher concentrations of alum lessen the primary antibody response, but the subsequent antibody levels and the rates of diminution in titers are nearly identical with the two sorts of vaccine.

Transient increase in resistance of mice to experimental infection following a small dose of x-radiation.

Summary CF-1 female mice, 9-10 weeks old, were exposed to a small dose of whole body X-radiation (50, 75, or 100 r) and together with unirradiated controls were challenged at various intervals by intraperitoneal injection of graded inocula of Pseudomonas aeruginosa. Comparison of the LD50s (30 days) of irradiated and control mice in each challenge showed a small but significant increase in resistance to the experimental infection during the 4th week following irradiation with 75 or 100 r. Exposure to 75 r was more effective than 100 r. The results suggest a possible explanation of “acquired radio-resistance.”

EFFECT OF DAILY EXPOSURE TO 15 r

Summary 1) CF-1 female mice were exposed to approximately 15 a day radiation for 9-15 weeks and challenged at intervals by intraperitoneal inoculation with graded doses of Pseudomonas aeruginosa. Comparison of LD50 of irradiated and control mice in each challenge showed that between 9th and 15th weeks a slight but demonstrable increase in susceptibility to experimental infection had occurred. 2) The increase caused by accumulation of 1350 r during 15 weeks exposure was, however, very much less than that resulting from a single acute exposure to 300 r X-radiation.

gamma

The culture medium described below has been found to yield a more plentiful growth of gonococcus than any we have employed. Additional advantages are transparency, low content of protein, and ease of preparation. Dissolve 40 gm. of powdered egg white†in a liter of 0.45% NaCl solution and adjust the reaction to pH = 7.0–7.4. Rub into a paste and add to the solution 4 gm. of a special high-test trypsin;‡ plug the mouth of the flask with cotton and incubate on a water bath at 48° C.—with occasional agitation—for 10-12 hours. This temperature prevents spoilage by inhibiting the growth of most micro-organisms. By the end of 10-12 hours, a sample of the digest should give an amino acid titration of 130-180 (i. e., cc. of N/10 NaOH per 100 cc. of digest) by Sörensens method. This determination is not essential, except as proof that digestion has proceeded satisfactorily, for we have found that a digest with a Sörensen titer of 80 supported growth as effectively as one with a titer of 180. Now add sufficient HCl to bring the reaction down to pH = 5.0, the isoelectric point of most of the proteins, and autoclave for 15 minutes. Add sufficient distilled water to bring the volume up to its original quantity. Then separate the precipitated proteins by filtration through paper or by centrifugation, and then by filtration through a Berkefeld candle. This sterile filtrate can be stored in the ice-box until needed. To this clear, straw-colored filtrate add 6 cc. of 0.04% phenol red solution per 100 cc. and readjust the reaction to pH = 7.0-7.2 with NaOH. The indicator in this concentration exerts no bacteriostatic action on the gonococcus, and its addition directly to the digest simplifies the adjustment of pH.

RADIATION ON SUSCEPTIBILITY OF MICE TO EXPERIMENTAL INFECTION

Summary Intraperitoneal or intravenous injection of RNA or yeast autolysate before or after irradiation with 475 r reduced the mortality of mice from experimental infection with Pseudomonas aeruginosa initiated by intraperitoneal inoculation on the fifth day post-irradiation. Mortality was also reduced in unirradiated mice treated with RNA or yeast autolysate before inoculation with Ps. aeruginosa.

An Egg White Digest Medium for the Gonococcus.

Summary CF-1 female mice 4 weeks of age were exposed 6 days a week to 0.5, 1 or 2 r γ radiation/day. After 4 to 39 weeks exposure they were challenged by intraperitoneal inoculation of graded doses of Pseudomonas aeruginosa. No detectable effect on host resistance to this experimental bacterial infection was demonstrated. The authors express their grateful appreciation to the following members of Depts. of Medicine and Radiology, Univ. of Chicago: Dr. Leon O. Jacobson for use of the cobalt-60 room in Argonne Cancer Research Hosp. USAEC: Lawrence H. Lanzl for assistance in planning arrangements and for the dosimetric determinations; and George A. Sacher, Argonne Nat. Lab., Lemont, Ill. for many helpful suggestions.

Effect of RNA and Yeast Autolysate on Experimental Infection in Irradiated and Unirradiated Mice.

Summary X-irradiated CF-1 mice lacking normal serum bactericidal activity for Escherichia coli were injected intravenously with highly bactericidal mouse serum. Passively transferred bactericidins were lost so rapidly from the circulating blood as to be undetectable 20-30 minutes later. Following 2 intravenous injections 30 minutes apart, bactericidins disappeared almost as quickly as after a single injection. The disappearance rates of normal bactericidins and immune hemagglutinins were compared under identical experimental conditions by injecting a mouse antiserum to sheep cells which was also bactericidal. The half-disappearance time of sheep cell agglutinins in mice was approximately 2 days, that of normal bactericides, only a few minutes. The authors are indebted to Dr. William H. Taliaferro for his interest in this work, and for many valuable suggestion.