Human teeth fluoresce as a result of illumination by UV-light. The fluorescence characteristics of human teeth were investigated with respect to aging and the presence of caries. The nanosecond decay features of a tooth's fluorescence were measured using a time-resolved fluorescence microspectrometer. The fluorescence intensity and fluorescence decay curve were founded to be age dependent in dentin tissue; the fluorescence intensity increased and the fluorescence decay time decreased with increasing human age. This may result from a gradual maturation of the fluorescent cross-linked collagen, such as pyridinoline, which increases markedly with age. The fluorescence intensity, anisotropy and fluorescence decay curves of carieous enamel were similar to that of hydroxyapatite than to the sound enamel. The data suggest that both quantitative and qualitative changes in the organic matrix of enamel may affect the fluorescence of caries tissue.

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Effects of testosterone propionate (TP) and/or insulin (Ins) on the proliferation and differentiation in the osteoblastic cell line: MC3T3-E1 were studied. MC3T3-E1 cells were incubated in a serum-free α-MEM medium containing 0.1% BSA with or without 10^-9-10^-6M TP and/or 10^-9-10^-6M Ins, and[³H]thymidine incorporation into the cell was assayed for assessment of DNA synthesis, and the ALPase activity of the cell was also assayed. Results were obtained as follow: 1. The time related decrease of DNA synthesis of MC3T3-E1 cells in serum-free medium was strongly inhibited by Ins. TP showed weaker effect than Ins. Combination of Ins and TP showed a weak synergistic effect. 2. TP significantly inhibited ALPase activity in dose-dependent manner. Ins also showed a tendency to inhibit ALPase activity. And the effects were strengthened by the combination of both, hormones. The effects of the Ins and TP on MC3T3-E1 cells will be expressed through the acceleration of proliferation ability of the cell, and the effect of Ins is stronger than TP.

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Dentine dysplasia has been known as exceedingly rare, congenital disease which cause the specific disformation of dentine. A son and a daughter, whose mother was already diagnosed as having this disease, were studied pathologically and biochemically in detail. Patients with teeth showing all of the clinical, radiographic, and pathological features of radicular dentine dysplasia (type I) have been found to have dense sclerotic bone. Biochemical analyses of the inorganic and organic components of dentine gave the following results: The inorganic component was preferred-oriented hydroxyapatite polycrystal. The Ca/P atomic ratio of 1.67, estimated by XRD, was not deficient in Ca, and agreed well with the theoretical value of stoichiometric hydroxyapatite. Most of the organic component could not be digested by pepsin and the collagen phenotype of the dentine was found to be type I. Examination of their general condition showed the patients to be suffering from osteosclerosis, which suggests the existence of a different type of dentine dysplasia, related to some general disorder.

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The purpcse of the present study was to clarify the mechanism of bone metabolism in diabetes mellitus. Morphological studies of fracture healing was focused mainly on bone formation and bone resorption in diabetic rats induced by the injection of streptozotocin.
196 Wistar rats of about 100 gram body weight were used.
In the diabetic group, the process of fracture healing was remarkably retarded. Microscorpically, new periosteal bone formation was disrupted. Ultrastructural findings of the osteoblasts disclosed irregularly dilated RER and other cytoplasmic organelle which were poorly developed, these contributed to the marked reduction of osteoid formation.
On the other hand, in the callus of the calcified cartilage, there was degeneration of the chondrocytes and at the same time, malformations of the cartilage matrix and disruption of the cartilage calcification. In addition, relatively many small osteoclasts were observed. The cytoplasmic organelle and the ruffled border were poorly developed and the uptake of bone crystals was minimal in the osteoclasts of diabetic rats.
These findings suggest that the retardation of fracture healing process in the diabetic rats is caused by a series of obstructions to the bone metabolism, such as obstruction of matrix formation, abnormal calcification and obstruction of bone regeneration. This observation is based on the cellular changes ultrastructurally and are thought to have a direct and indirect effect in case of diabetes mellitus.

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In order to clarify the membrane retrieval process after exocytotic secretion of submandibular gland acinar cells, the ultrastructure of membrane retrieval around acinar lumen and acinar canaliculi of normal adult male Wistar rats after exocytotic secretion of submandibular gland were investigated using freeze substitution fixation. The results showed that both luminal plasma membranes and intercellular canaliculi membranes had been coated on the inner leaf and the coated membranes subsided into the cytoplasm. The morphological details were as follows. The contents of granules were excreted into the lumen and intercellular canaliculi. The fused membranes made of both luminal plasma membranes and granular membranes had coated pits on its neck, side and lower bottom towards the basal cytoplasm. Several of the coated vesicles were observed toward fused membranes in the cytoplasm. The coated vesicles made of the fused membrances were observed as pentagons, hexagons and/or spheroids. Filamentous structures were seen as a belt-like structure around fused granule membranes, similar to the structure observed around the luminal plasma membranes.
From these findings, it was confirmed that (1) the granular membranes, which can not form coated vesicles, develop into a new form having the same ability as luminal plasma membranes and intercellular canaliculi after exocytotic secretion. (2) The fused membranes gain the ability to make coated vesicles. (3) The residual fused membranes are removed by endocytotic retrieval as coated vesicles. (4) Although the filamentous structures were not conspicuous immediately after exocytotic secretion, the slim and short filamentous structures appeared around vacuoles and fused granule membranes. (5) Also the filamentous structures showed belt-like structure surrounding them.
Furthermore, the present findings showed that the accumulated plasma membranes as the fused membranes are retrieved by the synergism of the filamentous structures and the coated vesicles.

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To investigate aging changes of mechanoreceptors in the oral mucosae, labial mucosae of 2, 12 and 18-month-old ddY strain mice were examined by light and electron microscopy. Whole-mount preparations of mice labial mucosae were stained using cholinesterase (ChE) -enzyme histochemistry, and observed by light microscopy. Two groups of ChE-positive corpuscles were identified: one was classified into lamellated corpuscles and the other bush-like non-lamellated corpuscles. The density of the lamellated corpuscles did not change with age but became more complex externally with aging. However, the bush-like corpuscles significantly decreased with aging. Simple, coiled simple, Meissner and Ruffini corpuscles were identified by electron microscopy. Ruffini corpuscles corresponded to the bush-like corpuscles seen by light microscopy, and the remainder corresponded with the lamellated corpuscles. Increased complexities of external and internal structures, and the elongation of mitochondria were observed in the coiled simple corpuscles of aged mice. Ruffini corpuscles in aged mice were charactarized by lamellar processes of terminal Schwann cells which covered empty axon terminals. Furthermore, multiple layered basal laminae were seen around the terminal Schwann cells which covered the axon terminals containing increased sizes of mitochondria. There were no submicroscopical differences in simple corpuscles between young and aged mice. However, the proportion of simple corpuscles against all lamellated corpuscles decreased with aging, and that of coiled simple corpuscles vice versa. The results suggest that simple corpuscles gradually change into coiled simple corpuscles.

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Histidine-rich polypeptides with histamine-releasing activity from rat peritoneal mast cells were isolated from human saliva by heparin-Ultrogel affinity chromatography and reverse-phase high performance liquid chromatography (HPLC). The amino acid composition of these peptides showed high proportions of histidine, lysine and arginine. The amino acid sequences determined by automated Edman degradation revealed that these peptides were completely identical to histatins 1, 3 and 5, respectively. Histatins 3 and 5 induced the histamine release from isolated rat mast cells accompanied with degranulation in a dose-dependent manner over the concentration range 5-40 μM, while histatin 1 was weakly active. The histamine release by histatin 5 was completed within 10 sec at 37°C. The temperature optimum for histatin 5-induced histamine release was in the range of 25-37°C, and the release was suppressed at temperature below 15°C and above 45°C. This activity was observed at acid to neutral pH's in the medium, but decreased at alkaline pH's. Their actions did not require extracellular calcium. This histamine release was not accompanied by leakage of lactate dehydrogenase. These results indicate that histatins 1, 3 and 5 can be isolated rapidly from human saliva by using a heparin column and HPLC, and that histatin 5 induces histamine release by means of calcium-independent exocytosis from the mast cells. It is suggested that histatins may possibly play a role in an early stage of inflammation in the oral cavity as naturally occurring host-defensive substances.

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BMP-induced heterotopic bone formation in mice was studied by light and electron microscopy. A BMP-preparation from bovine bone was enclosed in a gelatin capsule and implanted into the thigh muscles of AKR-strain mice. Tissues from implanted areas were examined on 5, 7, 10, 14, 21, and 28 days after implantation. By 7 days of implantation, undifferentiated spindle-shaped cells migrated into the BMP, proliferated by mitosis, and differentiated into chondrocytes, their cell membranes adhering to the fine granular BMP material; a homogenous cartilage was thus formed. Endochondral as well as perichondral ossification occurred in the BMP-induced cartilage following 14 days of implantation. The process of endochondral ossification was similar to that observed in the embryonic bone rudiments. In the perichondral ossification, the cells in the transitional region between the capsular tissue and the periphery of the cartilage became osteoblast-like cells. The extracellular matrix of these cells became calcified, and contributed to the formation of the cortical part of the new bone. A spongy bone with trabeculae lined by osteoblasts and osteoclasts was formed after 21 days of implantation containing actively proliferating bone marrow, which was mostly replaced by adipose tissue after 28 days.

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