PubMed Health⌕ Search

Biomedical subjects

J F Burd

Publications and source records attributed to J F Burd.

7 recordsLinked to original sources
PubMed1979

Substrate-labeled fluorescent immunoassay for phenytoin in human serum.

A homogeneous substrate-labeled fluorescent immunoassay has been applied to the measurement of phenytoin concentrations in human serum. We coupled a fluorogenic enzyme substrate, galactosyl-umbelliferone, covalently to a derivative of phenytoin. Under assay conditions, this drug-substrate conjugate was nonfluorescent but became fluorescent upon hydrolysis catalyzed by bacterial beta-galactosidase. When antibody to phenytoin is bound to the drug-substrate conjugate, it is inactive as an enzyme substrate. Addition of phenytoin to competitive-binding reactions relieves the inactivation, and the resulting fluorescence is proportional to the phenytoin concentration. We validated the fluorescent immunoassay by comparing values for phenytoin obtained with this technique to those obtained by gas chromatography and by enzyme immunoassay (EMIT). All three methods correlated well. The major metabolite of phenytoin, 5-(p-hydroxyphenyl)-5-phenylhydantoin, and other drugs at concentrations expected in serum had no effect on the assay. The fluorescent immunoassay is rapid and simple to perform and requires only 2 microL of serum sample per test.

Chromatography, Gas↗
PubMed1977

Homogeneous reactant-labeled fluorescent immunoassay for therapeutic drugs exemplified by gentamicin determination in human serum.

We applied a homogeneous reactant-labeled fluorescent immunoassay to the measurement of therapeutic drug concentrations in human serum, exemplified here by gentamicin. A derivative of umbelliferyl-beta-galactoside was coupled covalently to the drug and this conjugate was found to be nonfluorescent under assay conditions. The drug/dye conjugate was a substrate for bacterial beta-galactosidase and yielded a fluorescent product. When the drug/dye conjugate was bound to anti-gentamicin antibody it was inactive as an enzymatic substrate. This inactivation was relieved by the presence of gentamicin in competitive binding reactions. Hence, the rate of production of fluorescence was proportional to the gentamicin concentration. The fluorescent assay yielded values which compared favorably to a radioimmunoassay for gentamicin in clinical serum samples (r=0.94, standard error of estimate=0.66 mg/liter). The fluorescent assay requires only 1 microliter of serum and offers several advantages over existing techniques: sensitivity, specificity, simplicity, and the obviation of radioisotopes.

Cross Reactions↗
PubMed1975

Further studies on telestability in DNA. The synthesis and characterization of the duplex block polymers d(C20A10) - d(T10G20) and d(C20A15) - d(T15G20).

The synthesis and characterization of the duplex block polymers d(C20A10) - d(T10G20) and d(C20A15) - d(T15G20) are described. Thermal denaturation studies on these DNAs in the absence and presence of actinomycin, which binds only to the GC portions of these molecules, have confirmed and extended our previous observation that the properties of one region of a DNA can be influenced (telestabilized) by a remote region. In addition, the large scale synthesis of d(C15A15) - d(T15G15) is described.

Animals↗
PubMed1975

Transmission of stability (telestability) in deoxyribonucleic acid. Physical and enzymatic studies on the duplex block polymer d(C15A15) - d(T15G15).

The properties of the duplex block polymer d(C15A15) - d(T15G15) were examined by thermal denaturation and nuclease susceptibility studies in the absence and presence of drugs (actinomycin and netropsin) which bind specifically to only one end of the block polymer. The nucleotide composition of one region of this synthetic double-helical DNA affected the properties of a contiguous but remote region. Furthermore, the binding of actinomycin influenced the properties of both the binding and nonbinding regions. These findings suggest a mechanism for gene regulation at a distance.

Adenosine Monophosphate↗