Evaluation of a new urease reagent strip for detection of Helicobacter pylori in gastric biopsy specimens.

Objectives: Determine sensitivity and specificity of a new urease reagent strip (URS) test for detection of Helicobacter pylori in gastric biopsy specimens.

Methods: Six paired biopsy specimens were obtained from the greater curvature of the distal antrum, the lesser curvature near the incisura, and the corpus along the greater curvature during 66 procedures on 59 patients with endoscopic findings of gastric antral mucosal erythema or erosions, or gastric or duodenal ulcers. One biopsy from each site was tested with the URS.

Solid-phase analytical elements for clinical analysis.

The technology of dry reagent chemistries is sufficiently advanced so that analytical elements can be developed for almost any clinical analyte. Each element contains all the reagents and separation steps necessary to conduct an analysis. This provides the user with several advantages.

Analytical methods for therapeutic drug monitoring.

The availability of new immunoassay and chromatographic methods has led to the revolution in therapeutic drug monitoring. The immunochemical and chromatographic methods both meet the analytical requirements of sensitivity, precision, and accuracy needed for most TDM applications. The technique chosen for any laboratory will depend upon numerous factors such as the availability of personnel and equipment, the time required to perform the assay, the speed with which the clinician needs the results, and the cost and medical benefit to the patient.

A colorimetric immunoassay based on an enzyme inhibitor method.

A competitive binding immunoassay was developed using an enzyme inhibitor for labeling the analyte. Thyroxine was labeled by covalent coupling of the alpha-amino group to the gamma-carboxyl of the glutamyl residue of methotrexate. This thyroxine-methotrexate conjugate was a potent inhibitor of dihydrofolate reductase.

Homogeneous substrate-labeled fluorescent immunoassay for IgG in human serum.

A homogeneous substrate-labeled fluorescent immunoassay for IgG has been developed. Purified IgG was covalently labeled with 6-(7-beta-galactosylcoumarin-3-carboxamido)-hexylamine to form a stable conjugate, GU-IgG. The galactosyl residue was hydrolyzed from GU-IgG by beta-galactosidase and the progress of the hydrolysis was monitored by the increase in fluorescence emission at 450 nm with excitation at 400 nm.

The combined radioimmunoassay of triiodothyronine and thyroxine.

An RIA method for the concurrent determination of serum triiodothyronine (T3) and thyroxine (T4) is described. The extraction of the hormones from serum and competitive binding reactions using specific T3 and T4 antisera were conducted in sequence in a single Sephadex column. Precision studies resulted in average interassay relative standard deviations for T3 and T4 of 17 and 9.

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.

Immunoassay for serum thyroxine monitored by chemiluminescence.

An immunoassay for thyroxine (T4) monitored by chemiluminescence was evaluated with clinical serums. A thyroxine-label conjugate (T4-L) and serum samples were applied sequentially to alkaline Sephadex G-25 columns which adsorbed the thyroxine species. Other serum components and potential interferents were washed from the column with barbital buffer.

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.

Isolation of substances from urine by affinity chromatography.

The applications of affinity chromatography for the isolation and purification of physiological substances from urine have been reviewed. The use of affinity supports for the detection and measurement of various urinary components has also been briefly examined. These examples illustrate the usefulness of urine as a source of fine reagents and the versatility, simplicity and practicality of affinity isolation procedures.

Maternal serum unconjugated estriol and urine estriol concentrations in normal and high-risk pregnancy.

Serum unconjugated estriol levels and urinary estriol levels of concurrent specimens were compared for 6 normal and 6 high-risk subjects throughout the last trimester of pregnancy. Free estriol values in serum exhibited a close correlation with urinary estriol values for both the normal (r = 0.91) and high-risk (r = 0.

Direct radioimmunoassay for unconjugated estriol in pregnancy serum, with use of a radioiodinated derivative of estriol.

We describe a rapid and direct 125I-based radioimmunoassay for quantification of unconjugated (free) estriol in pregnancy serum. Estriol in serum is adsorbed onto a small column of Sephadex, thereby allowing its separation from proteins and interfering materials. A radioiodinated derivative of estriol (6-ketoestriol-6(o-carboxymethyl)oxime-[125I]tyrosine methyl ester) is added to the column, followed by a limiting amount of antiserum.