Atsushige Sato

Synthesis of procollagen by odontogenic cells of rabbit tooth germ.

Studies were performed to determine whether cultured odontogenic cells from rabbit tooth germ (RP cell) could synthesize dentine-like collagen. When cells were cultured with [14C]proline, 33% of the total incorporated proteins present were collagenous. Cultured RP cells were labeled with [14C]proline in the presence of beta-aminopropionitrile. The resulting fractions, on analysis by CM-cellulose chromatography, contained three radioactive protein peaks, alpha 1(I), [alpha 1(III)]3, alpha 2. From the radioactive measurements, RP cells synthesized a significant amount of type III collagen, comparable to type I collagen. DEAE-cellulose chromatography was used to separate collagen molecules from collagen precursors. The results showed that 60% of total collagen precursor was type III precursor and the remainder was type I precursor. CM-cellulose chromatography of CNBr peptides of collagen from culture medium and cell extract revealed the presence of type I and type III collagen. Thus, the RP cell, which is a diploid cell, is unique in the predominance of type III collagen in culture, differing thereby from the character of collagen in vivo.

Effects of sodium selenite on the cytotoxicity of dental amalgam

The antagonistic action of sodium selenite against dental amalgam-induced cytolysis in the L cells was studied using the 51Cr-release assay and photomicroscopic observations. Three pieces of dental amalgams (2.12 ± 0.04 cm2) were immersed in 1 ml of culture medium composed of Eagles minimum essential medium, 10% (vv) calf serum, and 10 mm Hepes buffer (pH 7.4), at 37°C for 96 hr. 51Cr-labeled L cells were incubated in culture medium containing 39.4% (vv) amalgam-dissolved solution (ADS) obtained above, at 37°C for 24 hr. Compared to the release of 29.1 ± 0.7% of 51Cr in the control, ADS-treated cells released 73.1 ± 1.5% of 51Cr which corresponded to the lysis of all cells. Morphologically, the ADS-treated cells underwent lytic changes. A simultaneous administration of 25, 50, and 100 μm sodium selenite produced a marked decrease in the 51Cr release of ADS-treated cells. Sodium selenite (50 μm) suppressed the elevated 51Cr release caused by ADS and prevented all of the morphological changes induced by ADS.

Evaluation of a new selenium-containing amalgam on mice.

Abstract The effects of a selenium-containing amalgam on mice were studied in comparison with the amalgam without selenium. The amalgam specimens were immersed in culture medium, and the amalgam-immersed medium was injected ip daily into mice for 7 days. In mice receiving the amalgam without selenium, the body weight of the mice did not increase and the proximal tubules of the outer medulla of the kidneys were disrupted. Whereas with the selenium-containing amalgam, the body weight increased and the renal tissues of the mice were not damaged. These findings suggest that there is a marked decrease in amalgam toxicity in mice when selenium is added to the amalgam alloy.