VDmax. A new method for substantiating 25 kGy.

Neither of the standards for the validation and routine control of sterilization of medical devices by ionizing radiation provides detailed guidance on how to substantiate a 25 kGy sterilizing dose. This article describes the basis of a new method for substantiating this dose and how the resulting procedure has been applied in practice.

Genetic mapping of a bacteriophage resistance mutation, pha-1, and the thi-1 mutation in Bacillus licheniformis.

A mutation, designated pha-1, resulting in resistance to bacteriophage LP-52, mapped between gly-3 and pepA1 in Bacillus licheniformis by transduction with phage SP-15. The thi-1 mutation was also found to be linked to gly-3. The map order was thi-1--gly-3--pha-1--pepA1--his-9.

Production and some properties of catalase and superoxide dismutase from the anaerobe Bacteroides distasonis.

The catalase level of Bacteroides distasonis (ATCC 8503, type strain) varied with the amount of hemin supplied to the medium when the cells were grown in either a prereduced medium containing 0.5% peptone, 0.5% yeast extract, and 1% glucose or in a prereduced, defined heme-deficient medium. The effect of hemin on catalase production could not be duplicated by ferrous sulfate or ferrous ammonium citrate. Catalase activity reached peak values in late log phase, whereas superoxide dismutase specific activity remained constant throughout the culture growth cycle. The catalase was a nondialyzable, cyanide and azide-sensitive, heat-labile protein that coeluted with bovine erythrocyte catalase from Sepharose 6 B. Analysis of polyacrylamide gels stained for catalase activity and for heme showed a correspondence between the single catalytic activity band and one of three heme-protein bands. These data suggest a heme-protein of approximately 250,000 molecular weight. The superoxide dismutase was a cyanide-insensitive protein of approximately 40,000 molecular weight that migrated electrophoretically on acrylamide gels as a single band of activity.

Surgical ligation clip artifacts on CT scans.

Surgical ligation clips of various materials were scanned in a water-filled phantom to determine what artifacts would be produced. Tantalum clips produced severe image degradation, while stainless steel clips produced less severe degradation. Minimal artifacts were observed with titanium clips. Clips molded from an absorbable polymeric material, polydioxanone, were visible on computed tomography (CT) scans and had the least effect on the CT image.

Amantadine hydrochloride inhibition of early and late stages of lymphocytic choriomeningitis virus-cell interactions.

Amantadine hydrochloride inhibits the CA1371, UBC, and WE strains of LCM in both BHK21/13S and L-929 cells. The compound has no direct inactivating effect on virus infectivity nor does it affect the adsorption of virus to cells. By observing the susceptibility of cell-adsorbed virus to neutralizing antibody, amantadine was shown to delay virion penetration. Furthermore, addition of the drug at any time during ongoing viral replication, with all cells scoring as infective centers, inhibits virus synthesis and release.