Effects of cadmium acetate and sodium selenite on mucociliary functions and adenosine triphosphate content in mouse trachea organ cultures.

The effects of cadmium acetate and sodium selenite in mouse trachea organ culture have been studied separately and in combination. Ciliary activity, morphology, rate of total protein and glycoconjugate (i.e. glycoprotein and proteoglycan) synthesis/secretion and ATP content were investigated. Exposure to 10 microM cadmium acetate or 2000 microM sodium selenite resulted in a complete cessation of ciliary activity within 5 h. With cadmium acetate also a swelling of epithelial cells was observed. Sodium selenite (250-2000 microM) delayed by 2-3 h the inhibitory effect of cadmium acetate (5-20 microM) on ciliary activity. The rate of protein synthesis, as determined by incorporation of [3H]proline, was reduced by 13% and 44% at exposure for 4 h at 37 degrees C to 250 microM and 500 microM sodium selenite respectively, the effect being partly abolished by cadmium acetate. With 5 microM and 10 microM cadmium acetate the rate of glycoconjugate synthesis, as measured by incorporation of [3H]glucosamine, increased by 50% and 69%, respectively, after incubation for 4 h. This increase was partly reduced by sodium selenite. Neither cadmium acetate nor sodium selenite had any effect on the rate of total protein or glycoconjugate secretion. The ATP content in trachea rings was reduced by 48% and 54% after incubation for 4 h with 250 microM and 500 microM sodium selenite, respectively. No significant effect of cadmium acetate was found on ATP content. An antagonistic effect of sodium selenite and cadmium acetate in mouse trachea organ culture is suggested from the present experiments.

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.

Concentrations of trace elements in human blood serum from different places in Norway determined by neutron activation analysis.

The concentrations of As, Fe, Hg, Sb, Se and Zn in 281 serum samples from people living in nine municipalities in Norway were determined by radiochemical neutron activation analysis. The concentrations of Br, Cl, Cs, Na, Rb, Se and Zn were determined in another set of 157 serum samples from four of the municipalities by instrumental neutron activation analysis. Higher arsenic concentrations were found in the coastal districts than in inland municipalities; otherwise no significant difference in mean values was observed between the districts. Except for Na-Cl and Rb-Cs, none of the elements was significantly correlated with any other element studied.

Effect of sodium selenite on the ciliary activity, adenosine triphosphate, and protein synthesis in mouse trachea organ cultures.

Trachea from albino mice were cut transversely into nearly identical rings and incubated in medium 199 with Hanks salts and HEPES buffer at 37 degrees C. Sodium selenite at 0.5-5 mM depressed the ciliary activity. With 1 and 5 mM sodium selenite, a 50% reduction in the activity index was observed after approximately 5 and 1.5 h, respectively. The ATP content in trachea rings was reduced with 0.05-5 mM sodium selenite, and increasing concentrations gave decreasing amount of ATP after incubation for 4 and 21 h. The rate of protein synthesis as determined by incorporation of radioactive leucine was reduced with 0.5 and 2 mM sodium selenite. The synthesis was reduced quickly by 2 mM sodium selenite, which gave a 30% reduction after incubation for 1 h. It seems that the ATP levels may be used as the most sensitive indication of sodium selenite toxicity in mouse trachea.

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.

Freezing of mouse embryos in the oviduct.

The survival of 2-cell and 4-8-cell mouse embryos after freezing and storage in liquid nitrogen, -196 degrees C, was examined. Both isolated embryos and embryo-containing oviducts were frozen to -40 degrees C at a cooling rate of 0.3 degrees C/min, and then transferred to -196 degrees C for one week. They were rapidly thawed in a 37 degrees C water bath at a rate of approximately 275 degrees C/min. Survival was assayed by in vitro cultivation of thawed embryos. The results indicated that freezing 8-cell mouse embryos directly or in the oviducts, is a reliable procedure for storing 8-cell embryos. By the procedure used, survival rates of 64% for the directly frozen embryos and 66% for the embryos frozen in the oviducts were obtained.

The use of frozen erythrocytes in macrophage studies. 2. Attachment and phagocytosis mediated by the two immunological receptors of the macrophages.

Sheep erythrocytes opsonized with IgG or C3b were frozen in various cryoprotective agents, thawed, and compared to corresponding unfrozen erythrocytes exposed to the cryoprotectants and to unfrozen erythrocytes not exposed to the cryoprotectants (controls) as test particles in macrophage attachment and phagocytosis assays. Fc-receptor-mediated attachment and phagocytosis were not influenced by the use of any cryoprotective agent tested or by freezing the erythrocytes. This was also the case with C3b-receptor-mediated attachment. Phagocytosis via this receptor was negligible in normal macrophages, but tended to be slightly more effective when the test particles had been treated with cryoprotective agents. In vitro stimulation of the macrophages with Escherichia coli endotoxin, however, triggered the capacity to internalize treated and untreated erythrocytes equally.

The use of frozen erythrocytes in macrophage studies. 1. Attachment to the foreign surface receptor of the macrophages.

The attachment of red cells to mouse peritoneal macrophages in vitro was tested with erythrocytes (from sheep and man) which had been subjected to different cryoprotective agents and freezing procedures. The experiments showed that with dimethylsulfoxide (DMSO) as the cryoprotective agent no difference in macrophage attachment was seen whether the erythrocytes were frozen or not. With the other cryoprotectants tested, macrophages were more efficient in attaching frozen than unfrozen erythrocytes. This was the case with erythrocytes from both sheep and man. Similar results were obtained with fresh (one week) and old (two weeks) erythrocytes.

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.

Whole-body autoradiography of 204Tl in embryos, fetuses and placentas of mice.

Whole-body autoradiography was used to study thallium uptake and retention in mice during gestation. Fifteen minutes after an intraperitoneal injection of 50 microCi 204Tl2SO4 into a 15-day pregnant mouse, thallium could be seen within the fetuses. Maximum fetal accumulation occurred 2-4 h after injection, and minimum at the last observation 4 days after injection. The fetal concentration of 204Tl was constantly lower than the placental. Uptake of 204Tl in embryos, fetuses and placentas of mice with gestation ages varying from 5 days to 16 days indicated that thallium crosses the placental barriers throughout gestation. Thallium was retained by the visceral yolk sac placenta during early gestation, by the visceral yolk sac, chorioallantoic placenta and amnion during late gestation. Over a period of time placental transfer and embryonic/fetal retention of small amounts of thallium may be hazardous to the offspring due to the high cumulative toxicity of this metal.

Manganese-nickel interaction in a tracheal ring model system.

The effects of NiCl2 and MnCl2 on the ciliary activity in mouse trachea were observed in an organ culture system. Following exposure for 2 hours to NiCl2 (0.5 or 2.0 mM) in Medium 199 40 respectively 0% of the ciliary activity remained. By simultaneous exposure to increasing concentrations of MnCl2 the toxic effect of NiCl2 was reduced and the ciliary activity following 2 hours incubation in the presence of 0.5 or 2.0 mM NiCl2 was 81 and 62%. At these nickel-concentrations optimal protection was obtained by about half the molar concentration of MnCl2. Preincubation in medium supplemented with NiCl2 followed by incubation in medium with MnCl2 added gave better protection than that obtained by changing to Medium 199 alone. Preincubation in 0.25 mM MnCl2 did not reduce nickel toxicity.

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

Salivary HBsAg in hepatitis B infection.

Hepatitis B surface antigen (HBsAg) was detected by solid phase radioimmunoassay (RIA) in mixed saliva of 15 out of 50 antigenemic patients. The salivary antigen was present in low titers for a short period of time in the acute stage of illness. Occult blood was detected in most mixed saliva samples. In parotid saliva neither HBsAg nor occult blood was found. Salivary HBsAg is probably due to admixture of blood or exudate.

Viral hepatitis in dentists in Norway.

Exceptions have occurred to the generally reported high prevalence of viral hepatitis in dentists. Thus a recent questionnaire survey (1) indicated a low risk of hepatitis in dental professionals in Norway. The present supplementary study was based on frequencies of serological markers of viral hepatitis and disclosed an exposure rate to hepatitis B insignificantly higher than that of the general population. The frequency of antibody to hepatitis A virus was equal to that of the general population.

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.

Secretion of nickel in rabbit saliva.

Secretion of nickel into unstimulated and stimulated saliva of rabbits was studied after a single intraperitoneal injection of nickel chloride labelled with 63Ni. Maximum 63Ni in unstimulated saliva was obtained in specimens collected one hr after maximum serum-63Ni was reached and two hrs after the nickel administration. Compared to serum-63Ni, the secretion of isotope into saliva was low whether or not stimulation was carried out. After 24 hrs, only traces of radioactivity were left in saliva. Forty to 60 percent of salivary-63Ni was ultrafiltrable. Most nickel associated with salivary proteins was weakly bound. Two acidic protein fractions obtained by gel filtration of saliva seemed to bind nickel firmly at neutral pH. No such binding of nickel to salivary proteins was observed after the in vitro addition of normal saliva to 63NiCl2.

Autoradiography of 90Sr in developing rats.

The distribution patterns of 90Sr in five littermate, 8-day-old Wistar rats were studied by whole body autoradiography. Rats were killed 15 min, 1, 4, 24, and 72 h after a single intraperitoneal injection of the isotope. Immediately after administration, 90Sr was distributed throughout most of the soft tissues of the body. The soft tissue deposits had practically disappeared after 4 h. In the hard tissues of the body 90Sr accumulated up to 24-72 h. Fifteen minutes after injection the uptake of 90Sr in the enamel of the teeth was highest in the occlusal and incisal regions. 90Sr gradually accumulated throughout the enamel and after 72 h its distribution in this layer was fairly uniform. Immediately after injection a narrow zone of radioactivity appeared in the dentin near the pulp. This zone broadened with time towards the dentinoenamel junction and included the entire dentin layer 72 h after injection. Initially, the uptake of 90Sr was higher in the dentin thatn in the enamel, particularly in the cervical areas of the crown. This difference became less apparent with time. There was good correlation between the uptake in teeth and bones, supporting the use of teeth as indicators of the 90Sr body burden.