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Biomedical subjects

C Couwenbergs

Publications and source records attributed to C Couwenbergs.

7 recordsLinked to original sources
PubMed1986

Relations between sex hormone levels and sexual behavior in men.

Using a sample of 33 healthy young men, 6 blood samples were obtained in the course of 2 weeks, and testosterone, dihydrotestosterone, and estradiol levels determined. The amount of free testosterone in the saliva was also ascertained for 23 of the subjects. All participants kept a daily record of their sexual activity during the investigational period. An interindividual comparison revealed a significant positive correlation between serum testosterone levels and the frequency of orgasms as well as a significant negative correlation between estradiol concentrations and the frequency of sexual activity without orgasm. The comparison of hormone levels to sexual behavior, prior to and after the individual sampling, reveals significant positive correlations between the serum testosterone and the extent of the free testosterone on the one hand and both the preceding and subsequent frequency of orgasms on the other. The estradiol levels showed a significant negative correlation with both the preceding and the subsequent frequencies of sexual activity without orgasm.

Adult↗
PubMed1985

Sex hormones and stress in the human male.

Six blood samples were obtained from each of a group of 33 healthy males between the ages of 19 and 31, following which radioimmunoassays were used to determine the serum concentrations of testosterone (Tser), 5 alpha-dihydrotestosterone (DHT), and estradiol (E2). In addition, the free testosterone (Tsal) was also measured using saliva samples provided by 23 of the subjects. A questionnaire of our own design was administered together with the Sixteen Personality Factor Questionnaire (16 PF-Test) at the time of the first blood sample in order to check the long-term stress loads of our subjects as well as their abilities to deal with stress. During the investigational period, subjects kept daily records of their sleeping and working hours and noted the appearance of stressful situations. Weather data for Hamburg was also included as a variable in this study. A number of significant relationships between sex hormones and stress could be ascertained; however, it should be kept in mind that the correlation coefficients are low and explain only a small percentage of the variance between the variables. The stress variables "weather condition" and the "Q4" factor of the 16 PF-Test are significantly related to E2 (intersubject correlations). For all samples of all subjects, psychic stress correlates positively with the ratio of Tsal/Tser. There is a significant positive intersubject relationship between Tsal and long-term plus concurrent somatic stress, while somatic stressors on the day preceding a blood and saliva sample (acute somatic stress) correlate positively with Tsal and Tser.

Adult↗
PubMed1976

Fluorogenic substrate turnover in single living cells.

Intracellular diffusion properties and enzyme activities in single living cells can be analysed by means of fluorogenic substrates that diffuse into the cells where they are converted into a fluorescent product by an enzymic reaction. The reaction-kinetic analysis of this process as a system of consecutive reactions provides information on the diffusion of the substrate into the cells, on intracellular enzyme activities and on the efflux of the fluorescent product. Separation of diffusion and enzyme-mediated processes is obtained by inducing specific changes of the cellular membrane using gramicidin D. A model for the functional interpretation of the experimental findings is proposed. Application of this method as a viability test for freshly prepared and frozen platelets is discussed.

Blood Platelets↗
PubMed1976

[Effect of cromoglicinic acid on the degranulation of mast cells (author's transl)].

An interference microscopic method is described which allows quantitative measurements of the inhibiting effect of the di-sodium salt of 1,3-bis(3-carboxy-chroman-5-yl-oxy)-2-hydroxypropand (cromoglicinic acid; Intal; DSCG) on the degranulation of mast cells in vitro induced by polymixin B and Compound 48/80. The specific degranulation inhibiting effect of DSCG is increased in the presence of Ca++ and Mg++ ions.

Animals↗
PubMedDate not supplied

Comparisons of the intra- and inter-individual variability in sex hormone levels of men.

Six blood samples were taken from each of 33 healthy young men during the course of 2 weeks. From these, the testosterone, dihydrotestosterone, and oestradiol levels were determined. In addition, free testosterone was measured using saliva samples obtained from 23 of the subjects. Both coefficients of variation and variance analyses showed that the inter-individual variability is greater than the intra-individual for all of the hormones. No influence of the day of the week could be ascertained. However, it was discovered that the serum hormone levels dropped with age (weakly significant for oestradiol, insignificant for the androgens) in spite of the subjects being in or near their third decade. The pooled intra-individual correlations between the hormones all fell within the moderate to middle-high positive domain, whereas the inter-individual correlations ranged between highly positive (testosterone to dihydrotestosterone), middle highly positive (free testosterone to total testosterone), and slightly negative (free testosterone to oestradiol).

Adult↗