The role of cellular Ca²⁺ and Mg²⁺ in signal transduction via P₂-purinoceptor was investigated using A-431 cells. Upon stimulation with ATP, cells incorporated ⁴⁵Ca²⁺ from their media. The rate of incorporation of ⁴⁵Ca²⁺ was rapid for the initial 5 min. ADP, UDP, GTP, UTP, AMP-PNP, and ATP-γ-S were also effective. The preincubation of cells in the medium depleted of both Ca²⁺ and Mg²⁺ abolished the ATP-dependent ⁴⁵Ca²⁺ influx irrespective of whether or not the subsequent incubation medium contained Mg²⁺ ion. On the other hand, the presence or absence of Mg²⁺ in the preincubation medium scarcely affected ATP-independent ⁴⁵Ca²⁺ uptake. ATPdependent ⁴⁵Ca²⁺ incorporation could be restored by the second preincubation in the medium containing Mg²⁺. The Mg²⁺ in the second preincubation medium could be replaced by either Ca²⁺, Co²⁺, or Cu²⁺ for restoration of such incorporation.
InsP₃ elevation stimulated by ATP was observed in the cells depleted of either Ca²⁺ or Mg²⁺ but not in the cells depleted of both ions. A parallel effect was observed in changes in intracellular Ca²⁺ concentration after exposure of cells to ATP. Therefore I conclude that amounts of Ca²⁺ and Mg²⁺ stored in cells which can be altered by extracellular environment, are responsible for ATPstimulated phospholipase C activation via P₂-purinoceptor, and that the activation of the enzyme may provoke ⁴⁵Ca²⁺ incorporation as well as intracellular Ca²⁺ mobilization induced by InsP₃ production in these cells.

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This study was undertaken to investigate the functional role of SI neurons which received input from intraoral structures and facial segments during mastication. A total of 582 single neurons were recorded in the SI cortex of 8cats awake. About 60% of 549 identified neurons showed neuronal activity change during mastication (mastication-related, MR, neurons). MR neurons received input from peripheral parts which were easy to stimulate during mastication. 94 % of MR neurons showed the rhythmical burst firing during mastication and 70 % of them received superficial input. Especially, some MR neurons which received superficial input from tongue showed a sustained burst of activities during ingestion. Some MR neurons which received input from the perioral parts showed the difference of activity patterns by directions which were stimulated.
These findings suggest that MR neurons that received superficial input are necessary for control of movements for performance of mastication.

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In the present study, the phagocytosis of latex particles and Staphyloco ccus aureus by Trichomonas tenax was examined, and production of short-chain fatty acids and induction of EB virus antigen were also investigated.
Larger latex particles (1.07μm in size) were enclosed sparsely by T. tenax and smaller size particles (0.15μm) were found to have accumulated within T. tenax cells. T. tenax began to enclose S. aureus into its cytoplasm after 10 minutes, and the action of phagocytosis of S. aureus by T. tenaxdeclined within 24 hours. Electron microscopic findings indicated that phagocytosis had initiated within 10 minutes, followed by the degradation of bacterial cells within 24 hours.
Acetic acid of 2.6 mM as a short-chain fatty acid in 5 ml of cultured fluids was producedby T. tenax and 2.0 mM by T. vavinalis, respectively. In addition, 1.0 mM acetic acid was produced by the isolated accompanying bacteria. These cultured fluids did not induce the EB viral antigens in terms of early antigen (EA).
The result obtained in the present study disclosed that S. aureus was enclosed and digested in the cytoplasm within 2 hours, besides, the cultured fluids of these trichomonad species did not induce EA because the inducers such as n-butyric acid could not be yielded.

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Salivary excretions of drugs in mice were investigated following the administration of antineoplastic agents such as 5-fluorouracil (5-FU), peplomycin (PEP), doxorubicin (DXR), and antibacterial agents such as tetracycline (TC), doxycycline (DOXY), minocycline (MINO), ofloxacin (OFLX), ciprofloxacin (CPFX), and tosufloxacin (TFLX), and sodium fluoride (NaF). In addition, concentrations of these drugs in whole saliva and in parotid saliva werecompared.There were significant correlations between plasma and saliva levels of 5-FU, OFLX and NaF. Therefore, the plasma levels could be estimated from the saliva levels in these drugs. The ratio of saliva AUC (area under concentration curve)/plasma AUC (S/P AUC ratio) was the highest in DXR, and it followed in the order of 5-FU, CPFX, NaF, OFLX, TFLX, PEP, MINO, TC and DOXY. A significant correlation between the S/P AUC ratio and plasma clearance was found in 9 drugs, excluding DXR. Accordingly, the saliva AUC could be estimated from the dose and plasma clearance. The flow rate of parotid saliva in submandibular and sublingual gland ablated mice, decreased to approximately one-third that of whole saliva in normal mice. Concentrations of 5-FU, PEP, doxorubicinol, OFLX and NaF in the parotid saliva were higher than those in whole saliva.

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Using serial focussing transmitted light through a differential interference contrast (DIC) and three-dimensional image analysis, the orientation and the structural changes of normal and abnormal prisms were observed in tangential ground sections of human enamel. The outer layer of permanent enamel consisted of a mild undulation of enamel prisms. The neonatal line of deciduous enamel showed a change in the prism arrangement. The alternation of a constriction and a varicosity with a periodicity of about 3-5 μm was identified as the cross-striations of prisms. Double bordered and spiral prisms in the inner layer of permanent enamel temporarily appeared on the way to the formation of normal arcade prisms. Stunted prisms in the outer layer, however, maintained the shape during a relatively long distance.

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Basic experiments were carried out to explore whether an organic phosphate, Calcium β-glycerophosphate (Ca-BGP), could be used as the medicament for direct pulp capping. Synthetic incu-bation medium nearly matched the exposed surface of the dental pulp. Crystal formation in this mediumby supplementation of serum and Ca-BGP was ultrastructually evaluated. After 3 hours of incubation, numerous globular structures, consisting of small granules were formed. These globular structures were identified as amorphous calcium phosphate (ACP) by electron diffraction and IR analyses. With time, globular structures decreased and needle-like crystals increased. Needle-like crystals were identified as hydroxyapatite (HAP) by electron diffraction. Alkaline phosphatase (ALP) activity in the medium with Ca-BGP decreased for up to 12 hours of incubation, and after that time, equilibrium occurred. These findings suggest that supplemented Ca-BGP is hydrolyzed by seru m ALP in the synthetic incu-b ation medium. Also the ACP is preferentially produced in high Ca X inorga nic phosphate (Pi) ion-product medium and finally ACP converts to thermodynamically stable HAP. Then, Ca-BGP could be used as new agent for direct pulp capping.

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