Akira Kameda

Effect of cyclic GMP produced by natriuretic peptides on osteoblast-like MC3T3-E1 cells.

The C‐type natriuretic peptide (10‐7 M) and atrial natriuretic peptide (10‐7 M) enhanced cGMP accumulation by 418 and 83 times the control value, respectively, in osteoblast‐like MC3T3‐E1 cells. The natriuretic peptide B receptor was assumed to be the major natriuretic peptide receptor. 8‐Bromoguanosine 3′,5′‐cyclic monophosphate (8‐Br‐cGMP) activated alkaline phosphatase doubled the activity versus the control value on day 15. Phosphodiesterase activity was not stimulated by the addition of cGMP (1 μM). cGMP‐dependent protein kinase (G kinase) activity of the supernatant fraction was 25.5 pmol/min/mg protein. The 42 kDa protein band was detected to be phosphorylated by G kinase on SDS‐PAGE. These results supported the hypothesis that natriuretic peptides regulate the differentiation of MC3T3‐E1 cells through a cGMP‐dependent pathway.

Longitudinal changes in the permanent dentition of traditional aborigines: Movements of the first molar and the anterior dentition

AbstractChanges in the permanent dentition that occur with growth in traditional Australian Aborigines have been reported by J. M. Barrett et al. (1965) and T. Brown et al. (1983–92). We undertook research on the longitudinal changes in the size of the permanent dentition of Aborigines by using a different method from that of the aforementioned studies. By focusing on the first molars, we analyzed movements in the anterior permanent dentition.We collected intra-oral plaster models of 50 male Aborigines and 50 female Aborigines, and measured the lengths and widths of the upper and lower dental arch triangles connecting the central fossae of the right and left first molars and the contact points of both central incisors of the subjects at around the ages of 8, 11, 15 and 19 years.1)Longitudinally, the lengths of the upper and lower dental arches decreased anteroposteriorly. On average, the decrease in the upper arch was 1.78mm for males and 2.63mm for females, and the decrease in the lower arch was 3.24mm for males and 3.78mm for females (p<0.01).2)Longitudinally, the widths of the upper and lower dental arches increased outwards. On average, the increase in the upper arch was 2.98mm for males and 0.96mm for females, and the increase in the lower arch was 2.11mm for males and 0.81mm for females (p<0.01). These trends were clearly substantiated by the statistical data.

Ultrastructural study on the interface between the original enamel and fluorapatite formed upon the tooth surface

AbstractThere have been few reports addressing the state of bond between synthesized fluorapatite on the enamel by the gel method and the existing enamel. The purpose of the present study is to examine the ultrastructure of the interface between the existing enamel and synthesized fluorapatite. The results are as follows.1.Scanning electron microscopy revealed a distinct border between synthesized fluorapatite and the existing enamel surface. Observation after acid erosion showed the evidence of demineralization at the interface.2.Transmission electron microscopy identified two distinct patterns at the interface between large fluorapatite crystals and the enamel surface: one involving a gap and the other with a direct contact. Synthesized fluorapatite and the enamel were separated by an intercalated layer of small immature crystals.3.Most of synthesized fluorapatite crystals were positioned vertically to the enamel surface and some were oriented irrespective of the enamel surface. Form these results, the bond between synthesized fluorapatite and the existing enamel seems to be weak, because of the presence of an intercalated layer of small immature crystals.