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Biomedical subjects

R A Olsen

Publications and source records attributed to R A Olsen.

27 records · Page 2Linked to original sources
PubMed1987

Synthesis, absolute configuration, and antibacterial activity of 6,7-dihydro-5,8-dimethyl-9-fluoro-1-oxo-1H,5H- benzo[ij]quinolizine-2-carboxylic acid.

The tricyclic quinolone antibacterial agent 6,7-dihydro-5,8-dimethyl-9-fluoro-1-oxo-1H,5H-benzo[ij]quinolizine -2-carboxylic acid has an asymmetric center at position 5 of the molecule. The R and S isomers of the compound have been prepared from the corresponding (R)- and (S)-2,5-dimethyl-6-fluoro-1,2,3,4-tetrahydroquinolines, which were separated via their diastereomeric amides of N-tosyl-(S)-proline. The absolute configuration was established by X-ray analysis of one of the diastereomeric amides. The 5-desmethyl analogue was prepared for antibacterial comparison with the isomers and the racemic mixture. It has now been established that the S isomer is much more active than the R isomer. The 5-desmethyl analogue was found to be more active than the R isomer but not as active as the S isomer or the racemic mixture. The importance of stereochemistry at position 5 in this system has been established.

Bacteria↗
PubMed1986

A versatile and easily fabricated mouthstick.

More and more handicapped individuals may be seeking dental treatment. Treatment may include construction of special devices to help these patients lead more productive and fulfilling lives. A mouthstick has been designed that can be constructed from readily available parts. The versatility and decreased cost of the mouthstick make it readily available to these needy patients.

Equipment Design↗
PubMed1983

Buoyant densities and dry-matter contents of microorganisms: conversion of a measured biovolume into biomass.

Several isolates of bacteria and fungi from soil, together with cells released directly from soil, were studied with respect to buoyant density and dry weight. The specific volume (cubic centimeters per gram) of wet cells as measured in density gradients of colloidal silica was correlated with the percent dry weight of the cells and found to be in general agreement with calculations based on the partial specific volume of major cell components. The buoyant density of pure bacterial cultures ranged from 1.035 to 1.093 g/cm, and their dry-matter content ranged from 12 to 33% (wt/wt). Average values proposed for the conversion of bacterial biovolume into biomass dry weight are 1.09 g/cm and 30% dry matter. Fungal hyphae had buoyant densities ranging from 1.08 to 1.11 g/cm, and their dry-matter content ranged from 18 to 25% (wt/wt). Average values proposed for the conversion of hyphal biovolume into biomass dry weight are 1.09 g/cm and 21% dry matter. Three of the bacterial isolates were found to have cell capsules. The calculated buoyant density and percent dry weight of these capsules varied from 1.029 g/cm and 7% dry weight to 1.084 g/cm and 44% dry weight. The majority of the fungi were found to produce large amounts of extracellular material when grown in liquid cultures. This material was not produced when the fungi were grown on either sterile spruce needles or membrane filters on an agar surface. Fungal hyphae in litter were shown to be free from extracellular materials.

Journal Article↗
PubMed1972

Salmonella testing of pooled pre-enrichment broth cultures for screening multiple food samples.

A method has been described for testing multiple food samples for Salmonella without loss in sensitivity. The method pools multiple pre-enrichment broth cultures into single enrichment broths. The subsequent stages of the Salmonella analysis are not altered. The method was found applicable to several dry food materials including nonfat dry milk, dried egg albumin, cocoa, cottonseed flour, wheat flour, and shredded coconut. As many as 25 pre-enrichment broth cultures were pooled without apparent loss in the sensitivity of Salmonella detection as compared to individual sample analysis. The procedure offers a simple, yet effective, way to increase sample capacity in the Salmonella testing of foods, particularly where a large proportion of samples ordinarily is negative. It also permits small portions of pre-enrichment broth cultures to be retained for subsequent individual analysis if positive tests are found. Salmonella testing of pooled pre-enrichment broths provides increased consumer protection for a given amount of analytical effort as compared to individual sample analysis.

Animals↗