Inhibition of virus growth by ouabain: effect of ouabain on the growth of HVJ in chick embryo cells

The effect of ouabain (g-strophanthin), a cardiac glycoside, on the growth of several enveloped viruses was examined. It was found that the growth of HVJ (Sendai virus) in chick embryo cells was markedly inhibited by the drug at a concentration as low as 5 x 10(-5)m. A virus-inhibitory concentration of ouabain did not cause morphological changes in uninfected cells, nor did it have the capacity to inactivate virus infectivity. Ouabain interfered with the intracellular synthesis of viral macromolecules. Although viral ribonucleic acid and viral antigens were synthesized by the ouabain-treated cells, the rate of synthesis was slower, and the total amounts of these macromolecules were smaller than those in the untreated control cells. It is suggested that ouabain inhibits the function of membrane-bound Na, K-adenosine triphosphatase of the chick embryo cells and thus prevents accumulation of K ion in them. Accumulation of intracellular K ion to a certain level would be needed for events of exponential growth of virus to proceed, and ouabain might inhibit this step by preventing such accumulation of K ion. This view was supported by the finding that the concentration of K ion in the HVJ-infected cells was rapidly reduced by the treatment with ouabain, and that, when the ouabain-treated culture was shifted to a medium containing a higher concentration of K ion than normal medium, virus production started in parallel with the increase of intracellular K ion. The fact that the concentration of K ion in BHK-21 cells, which support virus growth in the presence of ouabain, is not reduced by the treatment with the drug also suggested this possibility.

New type of R factors incapable of inactivating chloramphenicol

Four R factors conferring chloramphenicol (CM) resistance were isolated from Escherichia coli strains of clinical origin. Strains carrying the factors were found to be incapable of inactivating the drug in the presence of acetyl coenzyme A. E. coli W3630 carrying R(70), one of these factors, became sensitive to CM after treatment with glycine, indicating that the spheroplasts of W3630 R(70) (+) were sensitive to the drug and suggesting that the cell membrane is important for CM resistance. The observation that cell-free protein synthesis in W3630 R(70) (+) was inhibited by CM is also compatible with a decrease in permeability. CM resistance in W3630 R(70) (+) appeared to be inducible, because (i) preincubation with subinhibitory concentrations of CM prevented the prolonged lag noted for growth in the presence of 25 mug of CM per ml, and (ii) the preincubation effect was lost after overnight growth in CM-free medium. By contrast, E. coli W3630 cml(+), in which the resistance determinant is integrated into the chromosome, was capable of rapid inactivation of CM. E. coli W3630 cml(+) R(70) (+), which contains the proposed permeability determinant (episomal) as well as levels of the inactivating enzyme (chromosomal) that are comparable with W3630 cml(+), was capable of brief inactivation of CM when inoculated into drug-containing medium. The absence of continued inactivation on more prolonged incubation favors the hypothesis that the R(70) factor inhibited further penetration of CM and that this property possesses the characteristics of induction.

Epsilon-(gamma glutamyl) lysine in fibrin: lack of crosslink formation in Factor 13 deficiency

Fibrin clots formed in normal plasma contained about 6 mol of epsilon-(gamma-glutamyl)lysine per mol of fibrin, whereas those formed in plasma from individuals with Factor XIII deficiency contained little or none of this crosslink (0.02-0.64 mol/mol of fibrin). Partial supplementation of the plasma with Factor XIII, at a single concentration tested, commensurately increased the number of crosslinks.

Composition of human cerebrospinal fluid cerebroside

A technique was developed to isolate sufficient material for compositional analysis of cerebroside from pooled human cerebrospinal fluid. The carbohydrate moiety was principally galactose. The sphingosine base and fatty acid compositions were found to be similar to that of brain cerebroside. The presence of a contaminant in commercial silica gel which chromatographed like the trimethylsilyl derivative of glucose is described.

Isolation of hemagglutinin and neuraminidase subunits of hemagglutinating virus of Japan

When purified hemagglutinating virus of Japan (HVJ) was treated with trypsin, two major surface antigens were released from the virus. The "hemagglutinin" subunits obtained by this method were reactive with homologous hemagglutination-inhibition antibody and could be detected by an antibody-blocking test. They adsorbed to but did not agglutinate red cells and thus appeared to be "monovalent." The neuraminidase subunits were obtained in fully active form and did not adsorb to red cells. This finding suggests that these two activities of HVJ are associated with different subunits of the virus particle. The hemagglutinin and neuraminidase subunits could be partially separated by zonal rate centrifugation or gel filtration on Sephadex G-200. The molecular weights estimated for these subunits were approximately 124,000 and 114,000, respectively. After treatment with trypsin, virus-associated hemagglutinin and neuraminidase activities were both reduced significantly. The electron micrographs of such trypsinized virus particles showed complete or partial loss of surface projections. These results suggested that the subunits obtained by this method seemed to be those projections liberated from the virus by the action of trypsin.

Drug resistance of enteric bacteria. IX. Distribution of R factors in gram-negative bacteria from clinical sources

Many isolates belonging to the Enterobacteriaceae were collected in 1965 from the inpatients at geographically scattered hospitals in Japan. Among 2,650 Shigella strains examined, 58.4% were found to be drug-resistant; 95.0% of these resistant strains were multiply resistant. Among 434 resistant strains examined, 81% carried R factors that were transferable by cell-to-cell contact. Of 160 isolates of other enteric bacteria, drug-resistant strains included 84.2% of the Escherichia coli, 93.0% of the Klebsiella, and 90.0% of the Proteus cultures. Among these resistant strains, 70.3% of the E. coli, 66.7% of the Klebsiella, and 52.0% of the Proteus were multiply resistant. Of these resistant strains, 84.0% of the E. coli, 88.0% of the Klebsiella, and 50.0% of the Proteus strains carried R factors. These results indicate that R factors are widespread among gram-negative bacteria of clinical significance.