Biomedical subjects

Y Thomassen

Publications and source records attributed to Y Thomassen.

77 records · Page 5Linked to original sources

PubMedDate not supplied

Effects of low mercury vapour exposure on the thyroid function in chloralkali workers.

Forty-seven chloralkali workers exposed to mercury vapour for an average of 13.3 years were compared with 47 referents matched for age in a cross-sectional study of thyroid function. The mean urinary mercury concentration in the exposed workers was low compared with other studies of chloralkali workers: 5.9 nmol mmol-1 creatinine (range 1.1-16.8) vs 1.3 nmol mmol-1 creatinine (range 0.2-5.0) in the reference group. The median serum concentration of reverse triiodothyronine (rT3) was statistically significantly higher in the exposed subjects compared with the referents (268 pmol l (-1) and range 161-422 vs 240 pmol l(-1) and range 129-352; P = 0.009). The difference between the exposed subjects and the referents was most pronounced in the highest exposed sub-groups. The free thyroxine (T4)/free T3 ratio was also higher in the highest exposed subgroups compared with the referents. The median serum concentration of tumour necrosis factor alpha (TNF-alpha) was lower in the exposed subjects (7.3 pg ml(-1) and range 4.4-69.7 vs 8.0 pg ml(-1) and range 6.0-34.6; P = 0.004). Exposed subjects with the lowest urinary iodine (<67.8 nmol mmol(-1) Cr) had higher serum concentrations of reverse T 3 and a higher free T4/free T3 ratio than the other subjects, suggesting that a low concentration of iodine in urine may be a risk factor for increased serum concentrations of reverse T3 and the free T4/free T3 ratio in subjects exposed occupationally to mercury vapour. The study could indicate a slight effect of low mercury vapour exposure on the function of the enzyme type I iodothyronine deiodinase, possibly modified by comparatively low urinary iodine concentrations.

Adult↗

PubMedDate not supplied

Accessory sex gland function in normal young (20-25 years) and middle-aged (50-55 years) men.

A comparison of various parameters of prostatic and vesicular secretory function was made between the seminal plasma of young (20-25 years; n = 23) and middle-aged (50-55 years; n = 19) male volunteers. These parameters included prostatic acid phosphatase, zinc, citric acid, spermine, spermidine, putrescine (prostatic origin), fructose, and prostaglandin E (vesicular origin), in addition to protein and testosterone. Spermatozoa were counted and monitored for abnormalities. The concentration in the ejaculate of the majority of the parameters investigated did not change with age, although the total contribution to the ejaculate from the prostate and seminal vesicles was reduced significantly in the older men. The concentration of three constituents was significantly altered in the older age group: putrescine (P less than 0.001) and prostaglandin E (P less than 0.01) were reduced, while zinc levels were elevated (P less than 0.05). These changes are discussed in relation to possible disturbances of prostate function and pathology in the middle-aged man.

Acid Phosphatase↗

PubMedDate not supplied

Urinary selenium excretion in workers with low exposure to mercury vapour.

Urinary selenium excretion was studied in 21 mercury vapour (Hgo)-exposed workers involved in the demolition of a chloralkali plant. The subjects had no known previous occupational exposure to mercury. Their mean pre-exposure urinary mercury concentration, determined on average 1.2 days prior to the exposure, was 0.8 nmol mmol-1 creatinine (range 0.3-1.9). Their last mean urinary mercury concentration, determined on average after 51.4 days (range 19-103) of exposure, was 4.8 nmol mmol-1 creatinine (range 1.2-10.0). The exposure ceased on average 4.1 days after the last determined urinary mercury concentration. The corresponding concentrations of urinary selenium decreased from an average of 39.1 nmol mmol-1 creatinine (range 13.9-89.5) to 29.0 nmol mmol-1 creatinine (range 10.1-52.9) (P = 0.002). This finding may indicate that even a low to moderate work-related exposure to Hgo may reduce the urinary selenium concentration in humans in a manner that is not yet fully known.

Chemical Industry↗

PubMedDate not supplied

Human nickel exposure in an area polluted by nickel refining: the Sør-Varanger study.

Sør-Varanger municipality in northern Norway is located close to two Russian nickel refineries that cause nickel and sulfur dioxide pollution. To investigate individual nickel exposure and possible health effects from the pollution, the authors invited all adults who were 18-69 y of age to a health survey in 1994. Urine samples were collected from 3671 participants (participation rate = 59.4%), and nickel concentrations were determined for 902 of them. Mean and median nickel concentrations were 0.9 microg/l and 0.6 microg/l, respectively. Individuals who lived in the rural areas closest to the refineries had lower nickel concentrations than individuals who lived in the more urban areas. Independent risk factors for nickel concentrations in urine were (a) being an urban dweller and (b) living close to areas with high-density traffic. The authors concluded that nickel exposure attributable to air pollution from Russian refineries was of minor importance for people who lived in Sør-Varanger.

Adolescent↗

PubMedDate not supplied

Effects of oestrogen-induced hyperprolactinemia on the rat prostate.

Exposure of intact rats to increasing doses of oestradiol-17 beta in the presence of a constant amount of exogenous androgen caused a dose-related increase in the concentration of zinc in the lateral lobes and a decrease in the levels of ventral lobe prolactin binding. These changes occurred concomitantly with a dose-dependent increase in plasma prolactin levels, and could not be obtained in hypophysectomized rats given the same steroid treatment. In the intact animals a dose-dependent decrease in the responsiveness of the prostaglandin E1-dependent adenylyl cyclase in the ventral lobe was observed, an effect which has earlier been shown to be prolactin mediated. The results indicate that oestrogen has indirect effects on specific parameters of prostate function by inducing a relative hyperprolactinemia. This model may be useful in studying effects of chronically and physiologically elevated levels of endogenous prolactin on the rat prostate.

Adenylyl Cyclases↗