Harold E. Pearson

Increasing Bacterial Resistance to the Antibiotics A Study of 46 Cases of Streptococcus Endocarditis and 18 Cases of Staphylococcus Endocarditis

Observations on bacterial resistance to antibiotics in 64 patients with bacterial endocarditis are reported. Streptococcus endocarditis is contrasted with staphylococcus endocarditis as regards course, bacterial resistance to antibiotics, and mortality. The management of bacterial resistant patients is stressed and particular emphasis is placed upon the role of the newer antibiotics such as aureomycin.

Effects of Certain Amino Acids and Related Compounds on Propagation of Mouse Encephalomyelitis Virus.

Summary 1. Various amino acids and analogues in concentrations of 1-3 mg/ml inhibit the propagation of Theilers GDVII strain of mouse encephalomyelitis virus in tissue cultures of one-day-old mouse brain. The most active amino acid was L-lysine which was inhibitory at 0.5 mg/ml. The most effective analogues tested were the ortho-, meta-, or para-fluorophenylalanines, active at 0.1 mg/ml. 2. Partial reversal of lysine inhibition of virus growth was obtained with methionine, leucine, or tyrosine.

Production of Meningoceles and Cranioschisis in Chick Embryos with Lead Nitrate.

Conclusion (1) Injection of lead into the albumen of fertile eggs may result in the production of meningoceles in chick embryos. (2) Copper and mercury ions were noted to be as toxic as similar quantities of the lead ion, but meningoceles were not seen in the embryos surviving 13 days incubation. (3) Sodium salts of anion used in the metal experiments failed to produce meningoceles.

Inhibition of Mouse Encephalomyelitis Virus, in vitro, by Certain Nucleoprotein Derivatives.∗

Summary Adenine, adenosine, cytidine, guanosine and thymine inhibit the propagation of Theilers GDVII strain of murine encephalomyelitis virus in tissue cultures of one-day mouse brain. Guanine, uridine, uracil, guanylic or cytidylic acids did not inhibit. Various substituted nucleosides including amino-, chloro-, diazo-, formamido-, hydroxy- and methyluridine were inhibitory. Uridine partially reversed this inhibition. 5-Chlorouracil, ribosylthymine and glucosylthymine did not inhibit; 2,6-diaminopurine did. 5-Chlorouridine was not effective against this viral infection in mice.

In vitro conversion of radioglucose to free and protein-bound amino acids by virus-infected mouse brain☆

Abstract The amounts and specific activities of the free amino acids of minced 1-day-old mouse brain incubated 24 hr. with glucose-C14 in the presence and absence of Theilers GD VII virus were determined and compared with the corresponding values for the protein-bound amino acids. Virus propagation stimulated the incorporation of radioactive carbon from glucose into most of the free amino acids as well as the protein-bound amino acids. The specific activities of the labeled, free amino acids were higher than those of their protein-bound counterparts, suggesting that free amino acids were intermediates in the conversion of metabolites derived from glucose into protein-bound amino acids. The data suggest that the effect of the virus was primarily on the reactions leading to the formation of labeled amino acids rather than on the subsequent incorporation of the labeled amino acids.

Chemical Inhibitors of Theiler's Virus.

Summary Certain pyrimidine-related-com-pounds inhibit Theilers virus, in vitro. Inhibition by 5-hydroxyuridine is partially reversed by uridine-5′-phosphate. Of various other chemicals found to inhibit virus, in vitro, chlorpromazine and polymyxin did not protect mice from viral infection.

Propagation of Theiler's Virus in Murine Ascitic Tumors.

Summary Ascitic forms of murine astro-cytoma and ependymoma have been developed. These support growth of Theilers GD VII virus, in vitro, and under suitable conditions, in vivo. A variant strain of ependymoma, not susceptible to virus was obtained by passage of tumor in a partially tumor-resistant strain of mice. Ehrlich, Bashford 63 and Krebs 2 carcinomas and S3 7 sarcoma were not susceptible to Theilers GD VII virus, in vitro, or in mice.

In vitro inhibition of radiophosphate uptake and growth of a neurotropic virus by 5-chlorouridine.

Summary 5-Chlorouridine inhibits the propagation of Theilers GD VII virus and the uptake of P3204 by the ribonucleic acid fraction of minced, 1-day-old mouse brain but had no effects on other tissue fractions studied. Uridine partially reverses the inhibiting effects of 5-chlorouridine on virus propagation and on the uptake of P3204 by the ribonucleic acid fraction. Virus propagation has been shown to be associated both with an increased turnover and increased net amount of ribonucleic acid phosphorus.