Biomedical subjects
Publications and source records attributed to P J Shaffer.
A solid phase radioimmunoassay (RIA) was used to detect Aspergillus antigenemia in three patients, two with autopsy proved disseminated aspergillosis and one with a suspected infection. These RIA studies suggest that screening for antigenemia may be a specific and sensitive diagnostic test for disseminated aspergillosis.
Antigens were detected in the blood of rabbits infected with Aspergillus fumigatus by a solid-phase (tube) radioimmunoassay (RIA). The radiolabel for the assay was a polysaccharide-rich alkali extract (APAE) from the mycelia of A. fumigatus. Before this extract could be suitable labeled with 125I, it had to be conjugated with tyramine. Rabbits immunized with heat-killed mycelia had titers of antibody in serum of as high as 1:38,000 against this radiolabeled antigen. With unlabeled and unconjugated APAE as the standard antigen, the sensitivity of the RIA was 12 ng per test, or 500 ng/ml. Antigenemia was detectable by RIA three days after infection of rabbits with A. fumigatus. Blood cultures taken concomitantly were uniformly negative. These results indicate that antigenemia occurs in invasive aspergillus infection and in such cases can be detected by RIA. These observations may be important in the diagnosis of invasive aspergillus infections in humans.
2,2-Dimethyl-4-imidazolidinone derivatives of the alpha-amino acids DL-phenylglycine (1), DL-phenylalanine (2), L-tyrosine (3), L-histidine (4), and L-tryptophan (5) were prepared in order to assess their specificity in inhibiting amino acid decarboxylases. Treatment of th alpha-aminonitriles with acetone in the presence of base and heat or treatment of the alpha-amino amides with acetone gave the title compounds in 48-85% yield. The compounds afforded moderate ability to inhibit the decarboxylation of L-phenylalanine, L-tyrosine, or L-histidine in vitro, using crude enzymes. 3 was a better inhibitor of tyrosine decarboxylase (S. faecalis) than 2. 4 and 5 were comparable to 3 in inhibiting tyrosine decarboxylase. 4 was more selective in inhibiting purified histidine decarboxylase (Cl. welchii) than 5, which was inactive. 4 was inactive against fetal rat histidine decarboxylase in vitro.
In a study of active site binding the inhibition of thymidylate synthetase derived from Escherichia coli, calf thymus, and Ehrlich ascites tumor was examined using eight inhibitors. 5-Substituted 2'-deoxyuridine 5'-phosphate analogues used in this study are the hydroxymethyl, methoxymethyl, benzyloxymethyl, formyl, acetyl, allyl, and two potential active site alkylating substituents: 2,3-oxypropyl and the azidomethyl analogues. All compounds were competitive with the substrate, 2'-deoxyuridine 5'-phosphate; the most potent inhibitor was 5-formyl-dUMP (Ki = 0.1, 0.09, and 0.08 muM for the respective enzyme). The 5-hydroxymethyl, 5-benzyloxymethyl, and 5-azidomethyl derivatives of dUMP showed some differential inhibition; these compounds were two to three times more active against the ascites tumor enzyme than against the thymus enzyme.
Explore the source record for details and available documents.
Explore the source record for details and available documents.