The current work aimed to gain a better insight into the molecular states and functional significance of pyrophosphate ions (PPi) in media assimilated to human saliva. PPi exhibited complete inhibition of apatite crystal growth in a concentration range of 10-6M or higher. Experimental data also showed that PPi at corresponding concentrations could evoke precipitation of calcium pyrophosphate dihydrate (Ca₂P₂O₇·2H₂O) in the presence of 1mM Ca², giving rise to the loss of inhibitory activity. Fluoride at concentrations around 1ppm counteracted the inhibition of apatite precipitation by PPi. It is conceivable that increasing the driving force for apatite growth after fluoride addition allowed a growing step to squeeze between the adsorbed PPi molecules and then bury them in the lattice. On the basis of currently available information, we propose a delineated model to explain the behavior of PPi at the crystalsolution boundary in mineralizing milieus.

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The scar tissue that forms following palatoplasty in patients with cleft lip and palate causes numerous difficulties in orthodontic treatment. The most important function of collagen fibers in the body is to support the building of tissue. Although collagen fibers are the most ubiquitous fiber component, there are remarkable differences in their amount and structure, according to the functional demands of the tissue. Thus, in order to clarify changes in fiber structure that occur due to the contractile force of the tissue and to examine the role of collagen fibers in scar tissue of the palatal mucosa, we observed the differences in fiber structure in the lamina propria between the scar tissue present in the palatal mucosa of rats and the palatal mucosa of normal rats.
The fiber structure in the normal palatal mucosa had a mesh-like structure, consisting of collagen fiber bundles running antero-posteriorly and fiber bundles that intersected the above bundles and were observed to be in a relaxed state.
In the scar tissue of the palatal mucosa, thick fiber bundles were observed to be converging from the edge to the center of the wound, forming a bundle-like structure arranged in a radiating pattern. In addition, individual fibers were observed to be extended.
According to these observations, the fiber structure of palatal mucosa scar tissue is suggested to be such that, in addition to exhibiting characteristics of collagen fibers, it also fulfills the important role of serving as a source of physical resistance to external force.

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The minimal inhibitory concentrations (MICs) of 24 antimicrobial agents against two new species of the genus Capnocytophaga; C. haemolytica and C. granulosa, were determined by an agar dilution method, and were compared with those of other known species of the genus. All Capnocytophaga strains were susceptible to penicillin G, tetracycline, erythromycin, and ofloxacin, and were resistant to kanamycin, tobramycin, and polymyxin B. The activities of second- and third-generation cephalosporins varied among the species. Each Capnocytophaga species was highly susceptible to the following antimicrobial agents: C. haemolytica, penicillin G (MIC, 0.25-1μg/ml); C. granulosa, penicillin G and ofloxacin (MICs, 0.125μg/ml).

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Alkaline phosphatase (EC3.1.3.1) was purified from dental pulp tissues (4.5g) in rat incisors. The enzyme in dental pulps was initially extracted with n-butanol, followed by column chromatographies, such as DEAE-Sepharose CL-6B, Concanavalin A-Sepharose, Sephacryl S-300 HR and L-Histidyldiazobenzylphosphonic Acid Agarose. Finally, the enzyme was purified 95-fold higher than that found in the nbutanol extract and its recovery was 15% of the total. The final specific activity of the enzyme toward p-nitrophenylphosphate as the substrate was 1, 425U/mg protein.
Purified alkaline phosphatase was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing or non-reducing conditions with or without 5% β-mercaptoethanol and heating. Under non-reducing conditions, the purified enzyme had a molecular weight corresponding to 155k which was indicated on SDS-PAGE by both silver staining and enzyme activity staining with 5-bromo-3-indolylphosphate p-toluidine salt. However, the activity of crude enzyme in n-butanol extracts was found at 130k as well as 155k on the non-reduced type of SDS-PAGE. However, on the reduced type of SDS-PAGE, only one band corresponding to 77k was observed. Therefore, our findings showed that the alkaline phosphatase of rat dental pulp tissues is 155k and is composed of two subunits with identical molecular weights of 77k.
Furthermore, using this purification method, the molecular weights of alkaline phosphatase from pig dental pulp, rat bone marrow, kidney and mouse osteoblasts-like cells (MC3T3-E1) were found to be 185k, 155k, 158k, and 157k, respectively.

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We examined the fibrogenesis of elastic system fibers (oxytalan, elaunin and elastic fibers) and the effects of ascorbate on fibrogenesis in cultured human gingival fibroblasts ultrastructurally. The cultures accumulated an extensive extracellular matrix which contained collagen and elastic system fibers during a 6-week experimental period. Ascorbate (50μg/ml, α-MEM medium) increased collagen deposition, had no effect on microfibril deposition and completely inhibited elastin production. However, ascorbate at 1μg/ml (DM-170 medium) reduced collagen deposition and had no effect on microfibril or elastin production. The fibrogenesis of elastic system fibers was seen to proceed in two phases: the formation of parallel bundles of microfibrils (10-12nm in diameter) followed by the deposition within these bundles of amorphous elastin (elaunin fiber formation). Mature elastic fibers were not produced in cultures supplemented with a concentration of ascorbate during the experimental period.
Our observations suggest that microfibrils serve as sites for elastin deposition, and that ascorbate (50μg/ml) inhibits elastin production.

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