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At least 379 records · Page 21Linked to original sources
PubMed1982

Simultaneous fluorometry of urinary dopamine, norepinephrine, and epinephrine compared with liquid chromatography with electrochemical detection.

A simple fluorometric method is described for simultaneous assay of urinary norepinephrine, epinephrine, and dopamine. The catecholamines are separated by boric acid gel chromatography and subsequently determined by use of a modified trihydroxyindole reaction. By the separation with boric acid gel, dopa can be eliminated, which interferes with dopamine measurement; consequently, the reaction is specific for catecholamines. This simple, rapid method was applied to urine specimens from normal adults. Values for urinary dopamine, norepinephrine, and epinephrine agreed with those obtained by "high-performance" liquid chromatography with electrochemical detection.

Adolescent↗
PubMed1982

Simplified fluorometry of total metanephrines in urine.

We describe a simplified fluorometric method for quantitatively determining metanephrines in urine. The method is based on the elution of metanephrines from an ion-exchange column followed by production of a fluorescent derivative that has excitation and emission maxima of 405 nm and 505 nm, respectively. Metanephrine concentrations as great as 7.0 mg/L were within the linear range of the assay. Analytical recovery of metanephrines was 82-87%. Cross contamination by catecholamines was insignificant. The upper range of normal was 520 micrograms/24 h. Within-run and between-run CV's were 5% and about 9%, respectively. Twenty-four-hour urine specimens from five patients with pheochromocytoma showed above-normal amounts of the metanephrines by this method.

Adrenal Gland Neoplasms↗
PubMed1981

Urinary free catecholamines determined by liquid chromatography--fluorometry.

Free norepinephrine, epinephrine, and dopamine are determined in urine after purification on a small ion-exchange column and concentration on alumina. The catecholamines are separated by reversed-phase ion-pair chromatography and are quantitated by measuring their native fluorescence (lambda ex 285 nm, lambda em 305 nm). The internal standard is dihydroxybenzylamine. Within-day CVs for the compounds ranged from 1.6 to 5.6%; between-day CVs were 6.6 to 9.8%.

Chromatography, High Pressure Liquid↗
PubMed1980

Semi-automated fluorometry of total estrogens in plasma during late pregnancy.

We describe a mechanized method for determining total estrogens in plasma during the last trimester of pregnancy. This method involves rapid enzymic hydrolysis, automatic extraction (in a tube) with cyclohexane/ethyl acetate, purification of the extracted material by anion-exchange chromatography on a disposable "mini-column" of Dowex AG1 X 2 (acetate form), and continuous-flow fluorometric quantification. Conditions of hydrolysis and extraction were studied. The mean within-day imprecision (CV) was 7% and between-day imprecision was 8.1%. Sensitivity was 75 nmol/L of plasma. Results are obtained in 4 h. The technique is quite suitable for routine determinations: 90 assays can be done by a team of three technicians in one working day.

Estrogens↗
PubMed1980

Continuous-flow fluorometry of low galactose concentrations in blood or plasma.

Clearance of 0-100 mg/L concentrations of galactose from the blood depends on nutrient hepatic blood flow. We can measure such concentrations, which was not previously possible, by a continuous-flow method involving the use of galactose oxidase and peroxidase, the latter being coupled to a fluorogenic substrate, p-hydroxyphenylacetic acid. Interfering substances in the peroxidase reaction are removed by zinc/alkali precipitation. Sensitivity is maximized by using saturating concentrations of the enzymes and substrate. In prepared plasma test samples with galactose concentrations of 10, 40, 70, and 100 mg/L, the within-run CV's ranged from 2.1 to 8.6%, and day-to-day CV's from 2.2 to 17.2%, the largest CV's being for the 10 mg/L concentration. Normal subjects are shown to clear galactose more efficiently than subjects with moderate cirrhosis.

Anticoagulants↗
PubMed1995

[Comparison of 2 techniques for measuring lymphocyte proliferation: tritiated methyl-thymidine incorporation and propidium iodide fluorometry].

In vitro lymphocyte mitogenic stimulation by phytohemagglutinin A was determined in 20 subjects, comparing tritiated thymidine incorporation and nuclear propidium iodide fluorescence. Unexpectedly, no correlation could be found between the two measures. The pitfalls of both methods are reviewed and discussed. The inability to validate one test by the other restricts the interpretation of the results obtained with one method and prevents their generalization. Without another gold-standard at the present time, specific and limited method-dependent norms should be defined.

Fluorometry↗
PubMed1978

[Cell cycle phases: determination of G1, S e G2 by fluorometry (author's transl)].

The G1, S and G2 phases of the cell cycle in Allium cepa root tips were determined in Acriflavin--Feulgen--stained material. Pigeon erythrocyte nuclei were employed as standard for DNA dry mass determinations. Micro-interferometric and fluorometric measurements gave the average of 77,1. 10(-12) g for the G1 nuclei from the root tips.

Cell Cycle↗