Axial tooth movements and arterial blood pressure were measured following intravenous injection of adrenaline, 1hr before, and 1 and 2hr after the injection of tolazoline (an α-adrenergic blocking agent) or propranolol (a β-adrenergic blocking agent). The initial increase in blood pressure induced by adrenaline was significantly suppressed and the successive decrease in blood pressure was markedly enhanced by pretreatment with tolazoline. In contrast to blood pressure changes, the initial extrusive tooth movement induced by adrenaline was not suppressed, and successive intrusive tooth movements induced by adrenaline were not potentiated, but suppressed. The initial increase in blood pressure induced by adrenaline was enhanced and the successive decrease in blood pressure was suppressed by pretreatment with propranolol. On the other hand, the initial extrusive tooth movement induced by adrenaline was not significantly potentiated, but successive intnsive tooth movements induced by adrenaline were markedly suppressed. Pressure within the socket that may induce axial tooth movements might be regulated by various factors, such as resistance of the blood vessels, blood flow in the socket, and systemic arterial blood pressure, all of which are liable to change following an injection of adrenaline under the influence of α-or β-adrenergic blockers.

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Integration vectors have been used as genetic tools for mutagenesis in a number of organisms. We introduced random mutation into Streptococcus mutans with one of the vectors pVA891, and screened the mutants for the glucan-dependent aggregation-negative phenotype to isolate the genes involved in this property. Insertion of pVA891 containing a Sau3AI-digested host DNA fragment into the chromosome occurs following homologous recombination via a Campbell-like mechanism. This type of integration should generate a direct repeat of the homologous region at both ends of inserted pVA891. However, most mutants that we obtained do not have such a duplication and appear to have resulted from chromosomal rearrangements. For instance, the gbpC gene encoding the cell-bound glucan-binding protein was identified in the region deleted from the chromosome in one mutant. Several dozen other mutants exhibiting the nonaggregation phenotype harbored the intact gbpC gene and were shown to be diploid for large chromosomal regions. Based on the analysis of the chromosome from the duplication mutants, we propose that these deletions and duplications were generated by an unequal cross-over between two pVA891 sequences following multiple integrations of the vectors by a Campbell-like mechanism.

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The appearance and distribution of anti-cytokeratin 18 (CK18) immunoreactive cells in rat palatine rugae during fetal and postnatal development were investigated by immunohistochemistry and transmission electron microscopy. At the 17-day embryonic stage, most cells in the top area of palatine rugae displayed a positive immunoreaction for anti-CK18 antibody. These cells rapidly decreased in number during prenatal and postnatal development and became clusters of CK18 immunoreactive cells of various sizes. The cluster of CK18 immunoreactive cells in the top area of palatine rugae remained at least until the 14th postnatal day. Electron microscopy revealed that the CK18 immunoreactive cells in the top area of palatine rugae possessed characteristics of taste-bud cells. On the other hand, CK18 immunoreactive, elliptical cells which were smaller than the former cells appeared de novo in the hillside epithelium of the palatine rugae at 4 days after birth. As these cells possessed a large number of dense cored granules 120 nm in diameter and digital like cytoplasmic projections, and, in addition, were in close contact to the nerve terminal, they were categorized as Merkel cells. These Merkel cells drastically increased in number until the 14th postnatal day. The present findings indicate that palatine rugae of the rat in the fetal and infant stages possess taste buds, and that Merkel cells in the rat palatine rugae begin differentiation postnatally.

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The 90-kDa heat shock protein (HSP 90) is one of the major stress proteins in eukaryotic cells. There are at least two HSP 90 genes; and two HSP 90 isoform proteins, HSP 90 α and HSP 90 β, are expressed by them, The third member of HSP 90 family proteins, the 94-kDa glucose-regulated protein (GRP 94), is expressed in the endoplasmic reticulum, The purpose of the present study was to investigate the structures of HSP 90-family proteins and their expression in osteoblastic cells (MC 3 T 3-E 1) and in mammalian tissues. All three HSP 90-family proteins of human origin were expressed in a bacterial expression system and were purified to near homogeneity. Two kinds of polyclonal antibodies against human GRP 94 (hGRP 94) were obtained by immunization of recombinant protein and a synthetic peptide (residues 336-349) of hGRP 94 as antigens. The results of limited proteolysis of recombinant hGRP 94 with trypsin suggested three domain structures, similar to those of HSP 90 α. The expression level of HSP 90 isoforms in various rat tissues and in MC 3 T 3-E 1 cells under nonstress conditions revealed the predominance of HSP 90 β in most tissues (including oral tissues) except for the brain, testis, and reticulocytes. The expression of HSP 90 α in MC 3 T 3-E 1 cells was induced under stress conditions such as exposure to arsenate, whereas HSP 90 β and GRP 94 were not significantly increased.
These findings suggest that the three HSP 90 family proteins possess similar domain structures and that HSP 90 β is the major HSP 90 isoform expressed constitutively in the cell, whereas HSP 90 α is an inducible form.

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An extracellular protease was purified to homogeneity from a clinical isolate of Staphylococcus epidermidis from subgingival plaque of a periodontitis patient and its biochemical characteristics were determined. An apparent molecular mass of the protease, 27kDa, was estimated by SDS-polyacrylamide gel electrophoresis. The N-terminal 26 amino acids showed 69% identity to those of the mature form of Staphylococcus aures V8 proteinase. The pH optimum of the caseinolytic activity was about 8.0. The enzyme specifically catalyzed the hydrolysis of a carbonyl end of glutamic acid, and slightly hydrolyzed that of aspartic acid. Diisopropyl fluorophosphate potently inhibited the protease activity, followed by iodoacetic acid, whereas other inhibitors including EDTA and phenylmethanesulfonyl fluoride had little effect and dithiothreitol did not activate. The protease was predominantly observed in a bacterial culture obtained by the dialysis membrane technique, but was scarcely expressed in liquid culture either with or without shaking, nor in a culture on an agar plate without a dialysis membrane. Taken together, these findings indicate that the S. epidermidis 27-kDa protease is a novel inducible glutamic acid-specific serine protease related to V8 proteinase (EC 3. 4. 21. 9).

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This study set out to examine in vitro the action of dexamethasone (Dex), a synthetic glucocorticoid on the pulp cells of human teeth, particularly in the cell-rich zone of the pulp where cell density is especially high. The present experiment was performed on 10 third molars extracted from patients aged between 16 to 20 years for orthodontic reasons under local anesthesia. The teeth were otherwise found to be sound and free of dental caries. Upon extraction, each tooth was divided into two parts mesio-distally. Each part was then cultured separately in Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum for a period of 7 days. 100nM Dex, 1mM sodium-β-glycerophosphate and 0.2mM ascorbic acid were added to one half of the total cultures which served as the experimental group. Four areas of the pulp tissue, the roof, the root, the lateral wall and the base were then each divided into three layers of equal thickness measuring 150×33.0±8.26 (mean±S.D.) μm to correspond to the average thickness of the cell-rich zone and observed histological examinations of the cells were performed by hematoxylin-eosin (H.E.) staining and silver-binding nucleolar organizer region (AgNOR) staining. Results obtained from the test group cells showed a significant increase in the mean number of AgNOR in the roof and root areas in the cell-rich zone in addition to a slightly larger mean cell size in almost every zone. This shows that culture of 7 days in dexamethasone-added medium can lead to a heightened level of cell activity in the roof and root areas of the cell-rich zone.

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The present studies have been designed to clarify the influence of laser irradiation to the interface structure between existing enamel and synthesized fluorapatite by the gel method. Laser irradiation of a low energy density was carried out. Morphological investigations were perfomed focusing on the interface. The concentrations of Ca, P, and F in the surface layer did not decrease. A band layer was formed at the border line between synthesized fluorapatite and enamel after irradiation. Under transmission electron microscopy, it was observed that the crystals from the gel method had fused with enamel crytals in the uneven borderline.
In conclusion, synthesized fluorapatite was inclined to fuse strongly with existing enamel after irradiation. This suggests that the discontinuity of the interface between these two areas can be improved by this method.

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