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Biomedical subjects

J C Hansen

Publications and source records attributed to J C Hansen.

At least 109 records · Page 6Linked to original sources
PubMed1989

Cadmium exposure in Denmark. Based on analyses of liver and kidney tissues.

To determine the cadmium exposure level in the Danish population, tissue samples of kidney and liver were collected over the period 1981 to 1987 at the Institutes of Forensic Medicine in Copenhagen, Odense and Aarhus. A total of 795 samples were collected, of which 143 were selected for analysis using, the criteria sudden violent death (accident, homicide or suicide). Cadmium concentrations in kidney cortex increased by age to a maximum of approximately 22 micrograms/g/g (w/w) in the age group 45-55 years and decreased in the older age group, while liver concentrations tended to increase throughout the entire lifespan. Cadmium concentrations in kidney cortex and liver were found significantly correlated. The findings are in good agreement with internationally published data, but lower than previously reported Danish concentration levels. The reason for this difference is discussed.

Adolescent↗
PubMed1988

Has selenium a beneficial role in human exposure to inorganic mercury?

Laboratory experiments have indicated that selenium acts as a powerful antagonist to mercury intoxication. The literature is reviewed and from this it is concluded that mercury and selenium react in various ways. 1) The mercuric ion binds to selenium to form a biologically inert complex leading to increased body burden of both elements. This reaction seems to take place only when a threshold of mercury exposure is exceeded. 2) Selenium influences the oxidation rate of elemental mercury and as such the distribution pattern. This reaction is influenced by the nature of the antioxidative system. In species with low glutathione peroxidase activity, mercury oxidation seems decreased which can lead to an increased brain uptake. In this process there is no threshold. 3) Selenium can, as part of the antioxidative defence system, counteract mercury induced lipid peroxidation. Other antioxidants e.g. vitamin E might be just as effective. Based upon the literature it is hypothesised that to man selenium is of no benefit in cases of exposure to mercury either as mercuric mercury or as vapours. The only protection against mercury will still be a low exposure level.

Free Radicals↗
PubMed1988

Mercury concentrations in blood from Danish dentists.

Blood samples from a group of 130 dentists and a control group of 40 blood-donors were analyzed by cold vapor atomic absorption spectrophotometry in order to evaluate the extent of mercury exposure. The median blood concentration of mercury was 4.0 (range: 1.2-19.2) micrograms/l for dentists and 2.0 (1.1-4.6) micrograms/l for controls (2P less than 0.01). Practice characteristics obtained in a questionnaire showed no statistically significant relationship to blood mercury, but 49 dentists having one or more fish meals per wk, had a median concentration of mercury, which was 47% higher than dentists seldomly consuming fish (2P less than 0.01). It was concluded that none of the examined dentists had blood concentrations above the level (35 micrograms Hg/l) associated with the hygienic threshold limit.

Adult↗
PubMed1988

Serum concentrations and accumulation of silver in skin during three months treatment with an anti-smoking chewing gum containing silver acetate.

Silver acetate chewing gum was used for 12 weeks as a smoking deterrent in 21 adults. The effect of silver on serum concentrations, its accumulation in the skin and the risk of developing clinically evident argyria were investigated. Serum concentrations of silver clearly rose after chewing gum use had started, and concentrations quickly returned to normal after use had ceased. In most cases the number of silver granules in skin biopsies, observed by autometallography, increased after the gum had been used for 12 weeks. No one developed clinical signs of argyria. Silver acetate containing remedies can be used as an aid to stop smoking, but the consumption must be monitored to avoid accumulation of larger amounts of silver in the body.

Acetates↗
PubMed1987

Glutathione peroxidase activity in patients with rheumatoid arthritis and in normal subjects: effects of long-term selenium supplementation.

The effects of dietary supplementation with selenium were studied in 6 patients with severe, active rheumatoid arthritis (RA) and in 6 healthy control subjects. Initial concentrations of Se in red blood cells and in serum, and the activity of the Se-dependent enzyme glutathione peroxidase (GSH-Px) in red blood cells, serum, and granulocytes were significantly lower in RA patients compared with controls. During Se supplementation, however, the differences in Se levels and in GSH-Px activity between the 2 groups disappeared, except that, in RA patients, GSH-Px activity in granulocytes increased but remained significantly lower than in controls.

Adult↗
PubMed1987

Postmortem Menkes diagnosis from carrier testing of female relatives.

A boy who died at 6 months of age was noted to have sparse, stubby and light hair, pili torti were observed microscopically, and his skin was dry and redundant. As a suspicion of Menkes disease was first raised after his death, serum copper and ceruloplasmin in serum were not measured. Unfortunately, no fibroblasts were available - only fixed and paraffin-embedded samples of brain, spleen and liver. The copper contents of the brain and the liver were lower than in an age-matched control. Fibroblast cultures from the mother, the maternal grandmother, and a maternal aunt of the index patient were analysed for 64Cu-uptake. All these females showed the uptake values expected for Menkes carriers, thus supporting the clinical suspicion of Menkes disease in the index patient. From the above-mentioned results it was highly likely that the index patient had suffered from Menkes disease. Adequate genetic counseling could thus be offered to the family, and in the next pregnancy a first trimester prenatal diagnosis was performed.

Brain Chemistry↗
PubMed1987

Self-concept changes during youth-home placement of adolescents.

Youth status offenders typically present both mental health and behavior problems. This study describes a youth placement program and demonstrates self-concept enhancement through the program. Specific changes for boys and girls and different family structures are discussed.

Adaptation, Psychological↗
PubMed1986

Conformational transitions of the estrogen receptor monomer. Effects of estrogens, antiestrogen, and temperature.

The technique of aqueous two-phase partitioning has been used to study changes in estrogen receptor (ER) structure that occur upon ligand binding and/or heating in vitro. Studies with steroidal and nonsteroidal ligands indicate that the difference in partitioning properties between unoccupied and nontransformed ER is due to a ligand-induced change in this conformation of the protein. Furthermore, this conformational change is only partially induced by binding of 4-OH-tamoxifen. Although nontransformed 4-OH-tamoxifen complexes can be transformed by heat, there are significant differences in the transformation process for receptors bound to 4-OH-tamoxifen versus estrogenic ligands. A kinetic analysis of estrogen receptor transformation indicates that the process follows apparent first order kinetics, but is 2.5-fold slower for the 4-OH-tamoxifen-receptor complex. Direct heating of the unoccupied ER causes a significant change in receptor structure. Ligand binding to the heat-altered unoccupied receptor results in a further alteration of receptor structure. Experiments using polyethylene glycol palmitate indicate that the ligand-binding transition is associated with a reduction of the hydrophobic characteristics of the receptor. These results demonstrate that there are a number of independent conformational changes that occur within the monomeric ER steroid-binding subunit upon ligand binding and exposure to elevated temperature in vitro.

Animals↗