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Biomedical subjects

J Aaseth

Publications and source records attributed to J Aaseth.

At least 19 recordsLinked to original sources
PubMed1992

Dental amalgam and mercury.

The mercury concentrations in blood (HgB) and urine (HgU) samples, and in exhaled air (HgAir) were measured in 147 individuals from an urban Norwegian population, using cold vapour atomic absorption spectrometry. The study aimed to estimate the mercury exposure from the dental restorations, by correlating the data to the presence of amalgam restorations. Mean values were HgB = 24.8 nmol/l, HgU = 17.5 nmol/l and HgAir = 0.8 micrograms/m3. HgU correlated with HgAir, and both HgU and HgAir with the number of amalgam restorations, amalgam restored surfaces and amalgam restored occlusal surfaces. HgB showed poor correlation to HgU and HgAir and the presence of amalgam restorations. A differentiation of the mercury absorption due to exposure from dental amalgams and from the dietary intake, necessitates measurements of both organic and inorganic mercury in the plasma, and in the erythrocytes. The results suggest that individuals with many amalgam restorations, i.e., more than 36 restored surfaces, absorb 10-12 micrograms Hg/day.

Adolescent↗
PubMed1991

High serum selenium concentrations in reindeer breeding Lappish men.

This study investigated the relationship of serum selenium to its dietary sources in a group of Lappish men and a control population. Lappish men had higher serum selenium concentrations than non-Lappish men (1.79 vs 1.58 mumol/1; p = 0.003). Serum selenium correlated positively with consumption of reindeer meat, age and cholesterol. In linear regression models, however, being Lappish was the most significant predictor of high serum selenium. Lappish men ate more reindeer meat (p = 0.001) and less fish (p = 0.013) than men in the control group. Consumption of reindeer meat was also correlated with higher serum cholesterol levels. We conclude that high serum selenium concentrations in Lappish men may be important since low mortality from cancer is reported in this group.

Adult↗
PubMed1990

Selenium concentrations in the human thyroid gland.

Recently, we found that prediagnostic serum selenium concentration was significantly lower for cases developing thyroid cancer (n = 43) than for controls. We assumed that redistribution of serum selenium into the affected tissue took place in the prediagnostic period. The present study was carried out to determine the physiological concentration of selenium in the thyroid, since very few data are available in the literature. The concentrations of selenium in the thyroid (n = 45) and liver samples from Norwegians who had died because of acute illness or accidents were determined by hydride generation atomic absorption spectrometry. The mean selenium concentration was found to be 0.72 +/- 0.44 microgram/g in the thyroid and 0.45 +/- 0.11 microgram/g in the liver tissue. The surprisingly high concentration of selenium in apparently normal thyroids indicates that selenium has important functions in this organ. The remarkably broad range, together with the observation that no significant correlation exists between thyroid and liver concentrations, suggest that factors other than the selenium status are important determinants for the selenium concentration in the thyroid gland. This observation is consistent with our hypothesis that in carcinogenesis, prediagnostic processes influence the serum-/thyroid-ratio of selenium.

Adult↗
PubMed1990

Mercaptodextran--a new copper chelator and scavenger of oxygen radicals.

The therapy of copper poisoning with mercaptodextran inhibits the copper-induced haemolysis, whereas 2,3- dimercaptopropanesulfonic acid (DMPS) may accelerate such haemolysis. Some aspects of the mechanisms of these effects were investigated. The possible generation of activated oxygen species during the interaction of Cu++ and chelating thiols was studied using a chemoluminiscent method detecting oxygen radicals. It was found that incubation of DMPS with copper ions or erythrocyte membranes was accompanied by generation of oxygen radicals. Mercaptodextran added to similar suspensions did not lead to oxygen radical production. And unlike DMPS, mercaptodextran acted as a scavenger of radicals generated by the xanthine oxidase/acetaldehyde system. The different ability of the chelating thiols to cope with free radicals may explain their different potentials to protect against copper-induced haemolysis. Our results also indicate that mercaptodextran may be a useful therapeutic agent in cases of haemolytic crisis in Wilson's disease.

Chelating Agents↗
PubMed1990

The determination of copper in human liver biopsy specimens by cup-in-tube ETAAS.

A method for the direct determination of copper in human liver biopsy specimens is described. The addition of a mixed Mg-Pd nitrate modifier is shown effectively to delay the volatilization of copper both from aqueous standards and the powered NISTBovine Liver to an appearance time comparable with the solid biopsy specimens. Calibration against solid liver reference materials is preferable compared with aqueous copper standard solutions. A number of copper absorption lines provide a wide range of sensitivities; the less sensitive Cu-line 222.6 nm was found optimal in the determination of copper concentrations in the range of 20-200 mg/kg in liver biopsy specimens. The copper concentrations measured in liver biopsy specimens from patients suffering from sclerosing cholangitis were considerably higher than those reported for a group of healthy persons.

Animals↗
PubMed1989

Prediagnostic serum selenium in a case-control study of thyroid cancer.

Sera from 43 persons who developed thyroid cancer on an average 4.8 years after blood sampling were compared with sera from controls. Three controls per case matched for sex, age, place of residence and year of blood sampling, with regard to serum selenium and serum copper. Cases were significantly lower in serum selenium than controls, and the estimated odds ratio of thyroid cancer increased from 1 for levels greater than or equal to 1.65 mumol/l, to 6.1 for levels 1.26-1.64 mumol/l, to 7.7 for levels less than or equal to 1.25 mumol/l. When time from blood sampling to diagnosis of the case was considered, it could be shown that the protective effect of high serum selenium concentrations was restricted to the last (less than 7) years prior to the diagnosis of thyroid cancer. The serum selenium concentration of cases tended to decrease relative to controls the shorter time was from blood sampling to the diagnosis. There was no difference between cases and controls with regard to serum copper.

Adenocarcinoma↗
PubMed1987

The interaction of copper (Cu++) with the erythrocyte membrane and 2,3-dimercaptopropanesulphonate in vitro: a source of activated oxygen species.

The therapy of copper poisoning and of Wilson's disease with 2,3-dimercaptopropane-1-sulphonate (DMPS) may increase the copper-induced haemolysis. Some aspects of the mechanism of this effect were investigated. The possible generation of activated oxygen species during the interaction of Cu++ and DMPS was studied using a chemiluminescent method detecting oxygen radicals. It was found that incubation of DMPS with copper ions (free or bond with erythrocyte membranes) is accompanied with generation of oxygen radicals. Activated oxygen species produced via O2- are able to increase the haemolytic effects of cupric salts. Hence DMPS treatment in cases of copper poisonings or Wilson's disease may involve risk of side effects on the basis of activated oxygen species generation.

Animals↗
PubMed1986

Diabetic control is improved by guar gum and wheat bran supplementation.

Twenty-eight insulin-dependent diabetics were treated with different dietary regimes for three periods of three months. Initially they used a white flour bread (run-in period), then their daily bread ration was enriched with guar gum (mean dose: 29 g), and then with wheat bran (mean dose: 33 g) in a randomized crossover pattern. Fasting and postprandial blood glucose levels were measured on filter paper spots collected once weekly at home, and other biochemical values were measured monthly. No improvement in diabetic control was seen during the run-in period. Mean postprandial blood glucose decreased from 12.0 +/- 3.8 mmol/l (mean +/- SD) in the run-in period to 9.7 +/- 2.8 mmol/l (p less than 0.01) in the guar period and to 9.7 +/- mmol/l (p less than 0.01) in the bran period. HbA1 decreased from 10.5 +/- 2.1% in the run-in period to 9.7 +/- 1.6% (less than 0.05) at the end of the guar period and 9.9 +/- 1.2% (not significant) at the end of the bran period. Only modest changes were seen in serum-lipids--total cholesterol decreased significantly in the guar period, but not in the bran period. In this study both guar gum and wheat bran were well tolerated and produced a substantial decrease in postprandial blood glucose.

Adolescent↗
PubMed1986

Trace elements and rheumatoid arthritis (RA)--pathogenetic and therapeutic aspects.

Rheumatoid arthritis is characterized by increased activity of macrophages which produce toxic forms of oxygen. Such oxygen has been suggested as mediator also of rheumatoid inflammation. Gold accumulates in lysosomes of the macrophages and stabilizes lysosomal and other cell membranes leading to reduced liberation of toxic oxygen. Intracellular production of metallothionein can be induced. Zinc in high doses parenterally can immobilize macrophages and also induce metallothionein-like proteins. Copper and zinc are components of SOD which detoxifies oxygen, and copper-thiolate complexes are reported to be anti-inflammatory. The therapeutic effect of penicillamine and other thiols like aurothiomalate may also be related to an anti-oxidative action. Therapeutic induction of increased intracellular levels of glutathione or administration of selenium in such a form that it incorporates into glutathione-peroxidase and increases the efficacy of the enzyme may lead to accelerated metabolism of toxic oxygen.

Arthritis, Rheumatoid↗