Jon Jonsen

Carnitine uptake into human heart cells in culture.

The uptake of radiolabeled carnitine and butyrobetaine has been studied in human heart cells (CCL 27). The uptake of carinitine is 3-10-fold higher in heart cells than in fibroblasts (pmol - mug DNA-1). The uptake of carnitine increases with temperature coefficient KT of 1.6 in the interval 10-20 degrees C and with a negligible uptake at 4 and 10 degrees C. The uptake of carnitine follows Michaelis-Menten kinetics with a KM of 4.8 +/- 2.2 muM and V = 8.7 +/- 3.2 pmol - mug DNA-1 - H-1. Carnitine uptake is suppressed 90% by NaF (24MM). Butyrobetaine is taken up into heart cells to the same extent as carnitine with a KM of 5.7-17.3 muM and V = 8.7-9.3 pmol - mug DNA-1 - h-1. Butyrobetaine inhibits competitively the uptake of carnitine and carnitine inhibits the uptake of butyrobetaine to the same extent. No conversion of radiolabeled butyrobetaine to carnitine, or carnitine to methyl choline was observed intra- or extracellulary during incubation. These data are compatible with a selective transport mechanism for carnitine which is also responsible for the uptake of butyrobetaine.

The content of lead, cadmium, zinc and copper in deciduous and permanent human teeth

The aim of the study was to compare the uptake of the trace metals lead, cadmium, zinc and copper, in deciduous and permanent teeth. The material consisted of teeth extracted in the Oslo area. The teeth were digested in hydrochloric acid, and analyses were made by differential pulse stripping voltammetry. Similar levels of cadmium and zinc were found in deciduous and permanent teeth. The copper content varied little in deciduous teeth, but in permanent teeth a wide variation in the copper levels was found. The content of lead in deciduous teeth was found to be higher than in permanent teeth.

Effect of sodium fluoride on LS cells.

The fluoride sensitivity and the lethal concentration of LS cells were determined. The cells were adapted to grow in the presence of lethal concentrations of fluoride. The adaptation persisted after removal of fluoride. Any possible binding of the fluoride to medium components was excluded.

Effect of nickel chloride and cadmium acetate on the development of preimplantation mouse embryos in vitro

Preimplantation mouse embryos were used to investigate the toxic effect of nickel chloride and cadmium acetate on early embryo development in vitro. Embryos at the 2- and 4-8 cell stage were cultured in approximately 0.05 ml of mouse embryo culture medium (No. 16), overlaid with paraffin oil and incubated in a humidified atmosphere of 5% CO2 in air for 48 h. NiCl2 . 6H2O was added to the culture medium at concentrations of 10-1000 microM, Cd(CH3COO)2 . 2H2O at concentrations of 10-50 microM. Morphological criteria were used to check embryonic development. Ten micromolars of nickel chloride affected adversely the development of Day 2 embryos (2-cell stage), whereas 300 microM was needed to affect Day 3 embryos (8-cell stage). Toxic effect of cadmium acetate on Day 2 embryos was observed at a concentration of 10 microM.

Whole-body autoradiography of 63Ni in mice throughout gestation.

Whole-body autoradiography was used to study nickel uptake and retention in mice throughout gestation. After an intraperitoneal injection of 50 muCi 63NiCl2 into a 16-day-pregnant mouse, nickel appeared rapidly in connective tissues. Prominent sites of radioactivity 72 h after injection included the visceral yolk sac, lung, gastrointestinal tract and kidney. Nickel crossed the placental barriers throughout gestation, i.e. the visceral yolk sac during early gestation, the visceral yolk sac and chorioallantoic placenta during late gestation. A marked uptake of nickel was seen already in the 5- and 6-day embryo. Fetal accumulation of nickel took place up to 16 days gestation. Whereas nickel was distributed throughout the early embryo, distribution became more differentiated with increasing gestation, imitating that in the mother. Penetration of nickel into the mouse conceptus makes possible a similar ability in the human conceptus.

Copper and zinc in human serum in Norway

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 μmol/1 and copper varied between 16.3 and 19.2 μmol/1. 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 (18.4μmol/l) than in males (16.5 μmol/1). For zinc the opposite sex-relationship was indicated with the highest values in males, 15.8 compared to 15.1 μmol/1 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 s...

Nickel toxicity in early embryogenesis in mice

The development of mouse embryos was studied after intraperitoneal injection of nickel chloride in the preimplantation period. A single intraperitoneal injection of NiCl2 . 6H2O in 0.154 M NaCl corresponding to 20 mg/kg body wt was given to groups of female mice on days 1, 2, 3, 4, 5 or 6 of gestation. Control groups were injected with 0.154 M NaCl. Caesarean section was performed on day 19 of gestation and the following parameters were recorded: implantation frequency, frequency of early and late resorptions, frequency of liver normal fetuses, abnormal fetuses and stillborns, and the weight of each fetus. The implantation frequency of females treated with nickel chloride on the first day of gestation was significantly lower than that of the controls. The size of the litters in the control groups was larger than that of the nickel treated dams, significant difference being observed on days 1, 3 and 5. NiCl2 . 6H2O injection also resulted in diminished body weights of fetuses on day 19 of gestation. The groups of nickel treated mice had a larger frequency of both early and late resorptions and the frequency of stillborn and abnormal fetuses exceeded that of the control groups. This study shows that, by the procedure used, nickel chloride may influence mouse embryos during the passage through the oviduct with subsequent effect on the development after implantation.U

Frequency of hepatitis in dental health personnel in Norway.

Hepatitis B infection is considered a risk to dentists and their ancillary staff. To evaluate the magnitude of the risk for personnel in dental practice in Norway a questionnaire survey and a serologic investigation was performed, both disclosing frequencies of hepatitis B insignificantly higher than those in the general Norwegian population. The occurrence of anti-HBs in the general population, represented by 800 sera, appeared to be lower than the corresponding values found in Sweden and Denmark.

Inhibitory effect of ricin on the development of preimplantation mouse embryos.

Preimplantation mouse embryos were exposed to ricin, a plant toxin, in vitro and in vivo. The effect was evaluated by morphological observations of the exposed embryos as well as by means of protein synthesis. Ricin was highly toxic to the preimplantation mouse embryo in vitro, the effect being greater on the 2-cell than on the 4-8 cell stage. Intraperitoneal injection of ricin induced a small number of fetuses with exencephaly.

Recovery of mouse embryos after short-term in vitro exposure to toxic nickel chloride

The development of preimplantation mouse embryos in vitro was adversely affected by the addition of nickel chloride (NiCl2 X 6H2O) to the culture medium. For day 3 (4-8 cell) embryos developmental cessation occurred after 48 h in culture, in NiCl2 X 6H2O-containing medium. However, transfer to NiCl2 X 6H2O-free medium after 5 min, 1 h, and 3 h exposure, resulted in regaining of the developmental capacity for a proportion of the exposed embryos. The in vivo development, in pseudopregnant recipients, of in vitro nickel-exposed embryos was not significantly different from that in control embryos. The results indicated that the effect of NiCl2 X 6H2O on the development of day 3 mouse embryos in vitro was reversible after a short exposure period.