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Neutron induced prompt gamma-ray activation analysis (PGAA) is applied for determining boron contents in volcanic rocks, which is an important element in the discussion of material circulation in volcanic arc systems. To evaluate the recycling of oceanic crust in Kyushu, we analyzed boron and other trace element contents in basaltic rocks from the area. The basalts from volcanic front have high B/Nb (2.9–3.7), B/Zr (0.1–0.2) and B/Sm (2.8–6.0) ratios, whereas those ratios in the basalts from backarc are extremely low (

Although heat stress can cause irritation in the dentin/pulp complex, little is known about the thermotolerance of pulp cells and their response to heat stress. We investigated cultured rat pulp cell responses to heat stress. Cells were subjected to a temperature of 42°C for 30 minutes, and HSPs, alkaline phosphatase activity, and gap-junctional communication were determined at various time points. Although only low levels of HSP70 expression were detected before heat treatment, heat shock markedly induced HSP70 expression, with it gradually increasing at 1 hour after being heated. HSP25, however, showed no dramatic change. Gap junction protein connexin43 rapidly degraded after heat treatment, recovering to normal levels within the following 6 hours. Alkaline phosphatase activity decreased immediately after heat stress, recovering after 1 hour. These results indicate that dental pulp possesses protective factors, including HSPs, and that it can recover viability of intercellular communication and alkaline phosphatase activity after heat stress.

We analysed the N1 latency and amplitude for non-target event-related potential (ERP) and the N1 and P3 latencies and amplitudes for the target ERP in a continuous 40-min auditory oddball task. The N1 amplitude at Fz of non-target ERP was significantly less in the 3rd session than in the 1st session. The N1 amplitude to the target ERP was not different among the three sessions. The P3 amplitudes at Fz and Cz of target ERP was significantly less in the 3rd session than in the 1st session. These results suggest that a number of intracranial neural generators of P3 might change in prolonged extension of an auditory oddball task.

In this paper, a nonequilibrium network which works as a dynamical associative memory is designed. The design is based on a new similarity measure between any stored pattern and a state of the network. Although conventional similarity measures, such as Hamming distance, direction cosine, and so on, are not detectable in a cross-coupled network, the similarity measure proposed in this paper is. The new similarity measure is employed in our design. The network should include the following properties in its output pattern sequence, so that the dynamics of cross-coupled network may be designed: 1) Stored patterns are frequently associated in the dynamical association. 2) The dynamical association is very robust against variation of distributed parameters. Property 1) is achieved by introducing the next two operation modes with inverse N-shaped function into the dynamics of the proposed network. 1) When the state of the network is close enough to a stored pattern at a time step, the state is forced to evolve at the next time step. 2) The state of the network converges to a stored one while it is not close to any stored patterns. By considering these two operation modes, the frequency of associating stored patterns is increased. The authors emphasize the property 2) which is very important for a silicon implementation of the proposed network. In the silicon implementation, parameters of the network must be represented by transistors, resistors, capacitors, and other electric components which exhibit variation in their characteristics. Thus the second property guarantees the easy silicon implementation of the nonequilibrium network proposed in this paper.

The purpose of this study was to investigate cellular responses of periodontal ligaments during tooth movement. Twenty-eight male Sprague-Dawley rats, weighing 200-250 g each, were used. To create the orthodontic force, elastic rubber blocks (0.65 mm thick) were inserted between the maxillary first and second molars on both sides. On days 3, 7, 10, 14, 21 and 28 after rubber block insertion, histopathological changes in both the tension and the pressure sides were examined by immunohistochemistry using proliferating cell nuclear antigen (PCNA) and by the TUNEL method. The ratios of PCNA-positive cells on the tension side 3 and 7 days after rubber block insertion were higher than those on the pressure side. The ratios of PCNA-positive cells on the tension side were highest at day 3 after insertion and then decreased during the remainder of the experimental period. On the pressure side, the ratios of PCNA-positive cells increased up to day 10 post insertion, then decreased from 14 to 28 days. The ratios of TUNEL-positive cells on both the tension and the pressure sides increased throughout the entire experimental period. These results indicate that the periodontal ligaments on the tension side are able to respond more promptly to orthodontic forces than those on the pressure side. The data also suggest that the ratios of cell proliferation and of cell death are closely related to the regeneration and reconstruction of periodontal ligaments which reflect the orthodontic force.

Kimura's disease, eosinophilic granuloma of soft tissues, is a chronic inflammatory condition and appears as subcutaneous tumor-like nodules in the head and neck regions. Histopathologically, it is characterized by the presence of lymphoid follicles, marked infiltration of eosinophils, fibrosis and vascular proliferation. This disease occurring in the orofacial region is relatively rare, only 14 cases having been previously reported. We describe 3 additional cases of Kimura's disease and discuss these in relation to angiolymphoid hyperplasia with eosinophilia.

Long-term repeated administration of isoproterenol (lPR) 2 mg/100 g bw, once daily for ten days, resulted in morphological changes in the intercellular junctions of rat submandibular glands, which were investigated by means of the freeze fracture technique. A significantly increased number of tight-junctional strands was present. These junctional strands extended much deeper toward the basal membrane than those in normal acinar cells. The basal frontier strands that branched from the networks of tight junctions were elongated and had either free-endings or terminal loops, which were more frequently observed in the IPR-treated acinar cells than in untreated acinar cells. Some of the strands of tight junctions were connected to small gap junctions. The diameters of gap junctions were not significantly different from those of control acinar cells. However, smooth areas devoid of particles were found intermingling with the usual packed particles in irregularly shaped small gap junctions. There was no significant difference between the desmosomes of IPR-treated and untreated acinar cells, in terms of either morphology or distribution. These changes in junctional morphology in the IPR-treated acinar cells resemble those seen in salivary glands during development, and in some experimental conditions including tumorous changes.

To elucidate the regenerative capability of the periodontal tissues, we carried out two experiments: (1) Regeneration of the gingival tissue following gingivectomy in rats. Ultrastructurally, regenerating junctional epithelium was similar in morphology to that of untreated animals and appeared to attach to the enamel after five days. Basal lamina and hemidesmosomes were produced faster at the enamel interface than at the connective tissue interface. Gingival tissue was completely regenerated seven days after the gingivectomy. (2) Regeneration of the cementum, periodontal ligament, and alveolar bone following intradentinal cavity preparation in dogs. In the early stages, the cavity was filled with an exudate and granulation tissue. Seven days after the operation, osteoblasts and cementoblasts were arranged regularly on the cut surface of the alveolar bone and dentin, respectively. Newly formed bone and cementum, and periodontal ligament grew to resemble pre-existing bone and cementum after 28-42 days. From these results, it is suggested that the periodontal tissues have an extremely high capability of regeneration.