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Biomedical subjects

J R Benson

Publications and source records attributed to J R Benson.

51 records · Page 3Linked to original sources
PubMed1992

Time out for TNM.

Explore the source record for details and available documents.

Breast Neoplasms↗
PubMed1984

Polymeric columns for liquid chromatography.

Polymeric columns are becoming used more frequently in modern liquid chromatography applications as improvements in polymeric packing materials are realized and as more applications are developed for these materials. Modern polymers have overcome earlier problems associated with their use; higher rigidity now allows them to be used at normal eluent flow rates resulting in faster analyses, and improved synthesis techniques have resulted in efficiencies comparable to the best silica materials, sometimes exceeding 100,000 plates/m. In addition, polymers offer distinct advantages over silica packing for particular applications. Because silica packings are readily degraded by aqueous eluents, they are not always suitable for separations involving ionic species. Polymeric columns are particularly useful in determinations of amino acids, peptides, proteins, organic acids, carbohydrates, and inorganic cations and anions. Polymers are also characterized by exceptional lot-to-lot reproducibility. Reproducibility is often problematic with silica packings, particularly the bonded phases.

Acids↗
PubMed1980

Peptide separations on substituted polystyrene resins. Effect of cross-linkage.

The effect of copolymer cross-linkage on the resolution of soluble tryptic peptides of human globin (alpha- and beta-chains) separated in columns containing substituted polystyrene resin classified to 11 +/- 1 micrometer has been examined. With both the cation and anion exchange resins, polymers of lower cross-linkage provided better resolution; inferior resolution was obtained with 12% cross-linked resins. It was also observed that microparticle anion-exchange resins could be used in columns maintained at 55 degrees instead of 35 degrees as used traditionally. Resolution and yield with 20 x 1 cm resin beds were generally as good as or superior to much longer columns of crushed bead resin of the same chemical structure.

Anion Exchange Resins↗
PubMed1977

Interspecies homology of RNA tumor virus proteins.

We report the application of a highly sensitive column chromatographic technique to the comparison of tryptic peptide maps of some RNA tumor virus proteins. By combining microbore ion-exchange chromatography with a sensitive fluorescent assay using o-phthalaldehyde, we obtained high-resolution peptide maps starting with only microgram amounts of protein. Our discovery of coincident peptides from the 15,000 and 30,000 molecular weight proteins from murine and feline leukemia viruses supports serological evidence for interspecies antigenic determinants; coincident peptides were also found for the 10,000 molecular weight proteins from these viruses, although immunochemical data did not reveal interspecies determinants. The relatively large number of coeluting peptides found in the 15,000 and 10,000 molecular weight proteins is strong evidence for the existence of homology.

Avian Leukosis Virus↗
PubMed1974

Growth of T-strain mycoplasmas in medium without added urea: effect of trace amounts of urea and of a urease inhibitor.

Urea is currently considered to be a requirement for the propagation of T-strain mycoplasmas. We report here the replication of T-strain 960 (ATCC 25023) in media prepared from dialyzed components with added putrescine and allantoin but without added urea, or in dialyzed medium containing small amounts of added urea. The least amount of urea which allowed growth in the medium without allantoin was above 10 mug/ml. The amount of urea estimated to contaminate the added allantoin or putrescine was 5 mug/ml or less, which is insufficient to support T-strain replication. T-strain 960 was grown in the presence of urea and the urease inhibitor acetohydroxamic acid AHA where the organisms multiplied at a slower rate in the presence of AHA than in its absence. Urea hydrolysis occurred with concomitant ammonia accumulation and pH increase in cultures with AHA added.

Allantoin↗