Richtigkeit und Genauigkeit der Catecholamin-Analyse: Ein Intra-Laboratorium-Methodenvergleich

Determination of urinary 3-methoxy-4-hydroxyphenylethylene glycol and its conjugates by high-performance liquid chromatography with electrochemical and ultraviolet absorbance detection

A simple method for the determination in urine of the norepinephrine metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) and its conjugated derivatives is described. After an extraction procedure similar to that described by Gaertner and Wiatr [J. Clin. Chem. Clin. Biochem., 18 (1980) 579] isocratic high-performance liquid chromatographic separation is performed. MHPG can be detected by either electrochemical or absorbance detection (278 nm). Free MHPG is determined directly, whereas MHPG sulphate and MHPG glucuronide are determined after enzymic hydrolysis. Since total MHPG, which represents the sum of these substances, is determined separately, a comparison of the results allows the effectiveness of the hydrolysis of the MHPG derivatives for each urine sample to be determined. For quantitation, the method of adding standard amounts of MHPG is used.

Comparison of two analytical procedures for the determination of free urinary catecholamines under the demands of shiftwork experiments

A typical shiftwork experiment was chosen to prove the validity of an automated procedure for the analysis of free noradrenaline and adrenaline in urine. The method consists of a column switching technique with an adsorption/elution clean-up and a reversed phase high performance liquid chromatography followed by chemical reaction detection based on the trihydroxyindole method. The analysis of variance was performed using a second data set obtained by a semi-automated procedure for which the accuracy had already been confirmed. The analysis of covariance showed that for field studies, as well as for laboratory experiments in which the variances contributed by the experiments themselves are greater than 10% rel., the data sets of the two methods provide the same information.

Work at sea: a study of sleep, and of circadian rhythms in physiological and psychological functions, in watchkeepers on merchant vessels. I. Watchkeeping on board ships: a methodological approach

The safety of a ship depends substantially on its bridge watchkeepers, whose alertness and efficiency must be maintained at all hours of the day and night. Fatigue, circadian rhythms, and sleep disruption occasioned by the unusual working hours of these personnel may all affect their performance. A methodology for assessing the magnitude of this problem is proposed. The application of this methodology in a large-scale shipboard study of merchant mariners on extended voyages is then described, and details given of the techniques used to measure sleep and activity, and temporal variations in a range of physiological und psychological parameters. A summary of the data collected in the study is provided as a reference point for the reports on the different aspects of the results that follow in subsequent articles.

Influence of coffee on the excretion of noradrenaline and adrenaline in urine. A pilot study for the comparison of two methodical models

In field studies, the excretion rate of urinary catecholamines is very often used as an indicator of strain. Interfering effects which are due to caffeine, for example, can only be quantified if the influence of coffee consumption on the excretion of catecholamines is known quantitatively. This was the aim of our study with five subjects, on five consecutive working days, and with a strict standardization of nutrition. The urine samples were specified with respect to the following parameters: sampling period, volume, urine status, density, creatinine, noradrenaline, and adrenaline. Adrenaline showed a significant correlation with coffee consumption, whereas noradrenaline did not. Moreover, it could be demonstrated that relating the concentration of catecholamines to the creatinine excretion is insufficient for work physiology studies, especially if the urine sampling periods are as short as 2h.