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Biomedical subjects

W Fibiger

Publications and source records attributed to W Fibiger.

8 recordsLinked to original sources
PubMed1986

Hormonal responses to a graded mental workload.

Three mental arithmetic tests of graded difficulty were presented to eight young male volunteers on consecutive days. The effort compensation patterns were investigated using urinary catecholamines and salivary cortisol. A significant increase in adrenaline excretion was found in response to all three tests. Urinary adrenaline was partially graded according to the level of difficulty of the tests. The response patterns to mental workload also included a significantly lower noradrenaline/adrenaline ratio and a higher adrenaline/dopamine ratio after the tests. No significant increase was found after the tests for noradrenaline and dopamine. Changes in salivary cortisol concentration during the tests were graded with respect to test difficulty between the easiest and both of the more difficult tests. Salivary cortisol concentration changes are proposed as the basis for field observations involving mental workload. It is concluded that mental workload causes distinguishable effort compensation patterns and that under certain conditions urinary adrenaline and salivary cortisol allow one to distinguish different mental workload levels.

Adult↗
PubMed1984

Urinary dopamine in physical and mental effort.

Dopamine in urine was investigated during three levels of physical stress (at 35%, 50%, and 75% VO2 max.) and three kinds of mental stress (delayed auditory feedback, vigilance task and arithmetic task). A statistically significant increase in excretion of dopamine was found in response to physical exercise and the delayed auditory feedback test. The response patterns (ratios noradrenaline/dopamine and adrenaline/dopamine) after physical and mental stress differed. The data presented support the possibility of using dopamine excretion and the above ratios to differentiate between mental and physical effort.

Adult↗
PubMed1984

Cortisol and catecholamines changes as functions of time-of-day and self-reported mood.

Six male graduate students, unrestricted in their lifestyle, collected their own urine over a seven-day period: it was analysed for cortisol, noradrenaline, adrenaline and dopamine. At each urination subjects self-assessed their mood. On two separate days, blood samples were collected at 4-hourly intervals for plasma cortisol assay. Mean plasma cortisol levels showed the expected circadian variation, but two subjects had divergent patterns. Mean urine cortisol accumulation also showed circadian variation with a 2-4 hour lag behind plasma values. Mean urine catecholamine levels showed both time of day and considerable individual variation. A statistical procedure, involving comparison of two models, was developed to determine differences between subjects' excretion patterns. An underlying common pattern of cortisol and catecholamines excretion was found. Regression of hormone levels against self-assessed mood changes revealed correlations of (1) adrenaline accumulation with physical fatigue, (2) cortisol with alertness and (3) ratios of adrenaline, noradrenaline and dopamine with tenseness and irritability.

Adult↗
PubMed1984

Relationships between catecholamines in urine and physical and mental effort.

Excretion of noradrenaline and adrenaline was investigated in two experiments which included 3 physical test sessions and 3 mental test sessions (Experiment X) and a week of real-life situations (Experiment Y). An increased excretion of both catecholamines was found during each test in Experiment X. The noradrenaline excretion discriminated well between physical and mental tests, but one i.e. 35% VO2max. Adrenaline excretion discriminated the arithmetic test (AT) from the other mental tests. The noradrenaline/adrenaline ratio (NA/A) separated the AT from all other tests. The different adrenergic response patterns to physical and mental effort were confirmed in the real-life situations. The NA/A ratio reflected these differences. It was over 5 for physical activities and between 2 and 3 for mental activities. The different response patterns allow one to differentiate between physical and mental effort.

Adult↗
PubMed1979

[Thermographic functional test in the diagnosis of vascular changes in the vibration syndrome].

Contactant thermometry of fingers' skin in thermal functional test is a routine examination common now in vascular changes diagnosis. The sensitivity of this test is increased by the use of a linear thermograph, averaging the temperature of the skin area being examined. In order to ensure correct measurement results, conditions and principles of the test performance must be observed carefully, as indicated by the authors. Evaluation of time thermograms of fingers' skin should involve three types of thermoregulating reaction: homoiothermic, poikilothermic and amphithermic. The first type may be numbered among absolute, whereas the other two among relative physiological standards. Evaluation should include: fingers' skin temperature before cooling, the rate of temperature rise between the 1st and the 5th minute after cooling and the temperature taken at the 15th minute after cooling. Repeated measurements allow to differentiate changes in fingers' skin temperature, resulting from a damage to vessels due to vibration, as well as a relative physiological standard.

Fingers↗