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Biomedical subjects

K Helgeland

Publications and source records attributed to K Helgeland.

At least 55 records · Page 3Linked to original sources
PubMed1982

Copper and zinc in human serum in Norway. Relationship to geography, sex and age.

Serum samples were collected from the adult population, age groups from 20 to 54 years, in 11 different Norwegian municipalities and analysed for zinc and copper by atomic absorption spectroscopy. Significant differences were found between several of the municipalities when the mean concentration of zinc in serum in 200 randomized samples were compared, with only two municipalities being different for copper. The values for zinc ranged from 13.8 to 18.3 mumol/l and copper varied between 16.3 and 19.2 mumol/l. An age related increase in the copper concentration was evident in the male population, and age-adjusted means showed a slight, but significantly higher serum copper concentration in females (18.4 mumol/l) than in males (16.5 mumol/l). For zinc the opposite sex-relationship was indicated with the highest values in males, 15.8 compared to 15.1 mumol/l in serum from females. No significant correlations were found between the concentrations of zinc and copper in serum. In all age groups of women, however, a small negative correlation was found giving a significant tendency.

Adult↗
PubMed1981

Sensitivity of different human cell line in the biologic evaluation of dental resin-based restorative materials.

Three different cell lines of human origin, i.e. human epithelial cells (NCTC 2544), and epithelial- and fibroblast-like cells from human gingiva, were tested for their sensitivity to three different dental resin-based restorative materials using four different assay techniques. The techniques applied were cell growth measurements by cell number, 51Cr-release, agar overlay with neutral red staining and colony formation. The ranking of the cells according to their sensitivity to the materials varied with the assay technique applied, with no cell line being consistently more sensitive than the others. It is also suggested that the type of medium applied could be important for the results obtained.

Cell Count↗
PubMed1981

NH4Cl and protein metabolism in human gingival fibroblasts.

The biologic effect of ammonia was studied in cultures of fibroblasts isolated from human gingiva, NH4Cl in the range 2-20 mM was found to exhibit a concentration dependent growth inhibitory effect, with a delayed action which was most pronounced at low concentrations. Concomitant with the growth inhibitory effect a significant cellular accumulation of protein was evident. No effects on protein synthesis in general, as measured by 14C-proline incorporation, was found, whereas some inhibitory effect on collagen biosynthesis was indicated. Secretion of 14C-collagen and other labeled proteins was not affected. The only pronounced effect of ammonia on metabolism of the 14C-labeled proteins was an inhibition of the intracellular degradation of newly synthesized collagen, the lysosomes being suggested as the site for this degradation.

Ammonia↗
PubMed1977

Effect of some heavy metals on protein and collagen biosynthesis in rabbit dental pulp in vitro.

Cadmium, zinc, copper, and mercury, being components of dental alloys, have been tests at concentrations from 20 to 120 micronM for their effect on the incorporation of 14C-proline into various fractions of rabbit dental pulp incubated in vitro. With cadmium and zinc and increased amount of 14C-activity was recovered from the TCA-soluble pool, whereas the further incorporation into total protein and collagen, i.e. 14C-hydroxyproline, was markedly inhivited. Copper and mercury, however, reduced the amount of label in the TCA-soluble fraction. Both metals exhibited a dose-dependent inhibitory effect on the hydroxylation step in collagen synthesis, whereas for mercury only, an inhibition of the general protein synthesis was indicated. With all four metals the proportion of 14C-labeled protein and hydroxyproline recovered from the medium was reduced, the effect being most prominent with cadmium and zinc.

Animals↗
PubMed1977

Evaluation of biologic effects of dental materials using four different cell culture techniques.

The cytotoxicity of fresh and 1-day-old silicate cement, composite restorative material and zinc oxide-eugenol cement (ZOE) was tested using human epithelial cells (NCTC 2544) in four different cell culture systems: (1) 51Cr-release from prelabeled cells after incubation for 4 and 24 h in the presence of the materials. (2) Implanting the materials on an agar everlay and visualizing any cytotoxic effects after 24 h by neutral red vital stain. (3) Cell growth during 5 d in the presence of the materials. (4) Colony-forming ability after exposure of the cells for 30 min to medium previously incubated with the materials for 24 h. Freshly prepared and 1-day-old ZOE exhibited a prominent cytotoxic effect in all four systems. A less marked effect was found for the composite material in systems 2, 3, and 4, while silicate cement appeared to be the least toxic material in these three systems. Neither silicate cement nor composite showed any cytotoxic effect in system 1 based on 51Cr-release. It is concluded that the effects obtained by the cell culture techniques did not mimic the reactions obtained when the materials are tested under conditions which reflect their clinical use.

Cell Division↗
PubMed1977

PH and the effect of fluoride and zinc on protein and collagen biosynthesis in rabbit dental pulp in vitro.

The effect of pH in the range 6.6-8.2 on the incorporation of 14C-proline into the rabbit dental pulp incubated in vitro has been studied. The amount of label in the cold TCA-soluble pool, total protein, and hydroxyproline (i.e. collagen) of the pulp tissue increased linearly with pH in all three fractions. A similar increase was found in the amount of labeled total protein and collagen recovered from the incubation medium. The results indicated that the uptake of 14C-proline into the TCA-soluble pool was the pH-sensitive step, whereas the incorporation into protein, formation of hydroxyproline, and the release of labeled macromolecules into the medium were not affected to any measurable degree by the ambient pH. In this system, zinc (60 micrometer) had less effect on the incorporation of 14C-proline into the different fractions of the pulp tissue at pH 6.6 as compared with pH 7.4, whereas with fluoride (1.3 mM) an increased inhibition of the uptake of 14C-proline into the TCA-soluble pool and the incorporation into total protein was found upon lowering the pH to 6.8. The inhibitory effect of zinc and fluoride on the release of labeled total protein and collagen into the incubation medium was not affected when the pH was lowered.

Animals↗
PubMed1977

Toxicity of some dental cements in a cell culture system.

A cell culture method has been used to study the effect of zinc phosphate cement (De Trey's Zinc Zement Improved), zinc silicophosphate cement (Fluoro-Thin) and polycarboxylate cement (Durelon) on animal cells. Disks (20 x 1 mm) of the materials were placed in the center of plastic Petri dishes and subsequently incubated with human epithelial cells. Cell multiplication, medium pH and the release of cement constituents were measured. All three cements exhibited a cytotoxic effect, which was most pronounced in the cultures with zinc silicophosphate cement and polycarboxylate cement. The results also indicated that cell growth on the surface of the disks is a more sensitive indicator of cytotoxicity than cell growth around the disks. pH of the medium was only slightly affected in cultures with polycarboxylate cement, whereas a decrease was found in cultures with zinc phosphate cement and especially with zinc silicophosphate cement. A rapid release of phosphate was found in cultures with zinc silicophosphate cement. Zinc was released into the medium from disks of zinc phosphate cement, zinc silicophosphate cement and polycarboxylate cement--exceeding the toxicity level for the present cell line after 24 h. In cultures with zinc silicophosphate cement and polycarboxylate cement the release of fluoride reached toxic levels within the same time interval.

Cell Division↗
PubMed1976

pH and the cytotoxicity of fluoride in an animal cell culture system.

To investigate the mechanism for the toxicity of silicate cement as observed in a cell culture system, the effects of pH and fluoride were tested on human epithelial cells (NCTC 2544). At pH 7.3, fluoride concentrations from 15 to 25 mug/ml (0.79 to 1.3 mM) had a growth inhibitory effect. When pH of the incubation medium was lowered in the range 7.0 to 6.4, an enhanced cytoxic effect of fluoride was found, and even at 5 to 10 mug/ml growth inhibition occurred. Concomitant with the enhanced cytotoxicity of fluoride at low pH, there was an increased utilization of glucose and formation of lactate. Upon lowering the pH of the incubation medium from 7.4 to 6.7 a twofold increase in the intracellular concentration of fluoride was found.

Animals↗
PubMed1976

Effect of fluoride on protein and collagen biosynthesis in rabbit dental pulp in vitro.

The time course for incorporation of KC-proline into various fractions of rabbit dental pulp in vitro has been measured. In the TCA-soluble precursor pool a steady state level of activity was indicated upon incubation after 3 h, whereas incorporation into protein and 14C-hydroxyproline, i.e. collagen formation, increased linearly for 9 h, leveling off upon further incubation. A lag period of about 3 h was indicated for the appearance of high molecular weight 14C-activity, including 14C-hydroxyproline, in the medium, increasing linearly from 3 h to the end of the incubation period (22 h). In this system, fluoride exhibited a dose-dependent inhibitory effect. At 5.3 mM fluoride the uptake of 14C-proline into the TCA-soluble pool was inhibited by about 50%, and the incorporation into protein and the subsequent conversion to hydroxyproline by about 90 and 60%, respectively. Release of collagen, i.e. 14C-hydroxyproline-containing material, seemed to be the process most sensitive to fluoride; it was inhibited by about 50% at the lowest concentration (1.3 mM) tested.

Animals↗