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Crystalline as well as amorphous polymers and a thermosetting resin were hydrostatically extruded with pressures up to 4 kilobars. A linear relation was obtained between the extrusion pressure and extrusion ratio. Temperature of the billets during the extrusion process was determined, along with the flow pattern of the deformation. Tension tests at the temperature, to which the billet was exposed during the extrusion, was carried out at atmospheric pressure on the high-density polyethylene specimen to supply a theoretical basis to the experimental formula. Effects of temperature and strain rate on the extrusion process are discussed in the light of the temperature-time superposition principle.

Though Erythroplakia is said to be one of the precancerous lesions with a high malignant transformation rate, very few reports have so far concerned this disease in Japan. We recently experienced a case of Erythroplakia occurring on the lateral side of the tongu of a 36-year-old female. The lesion was surgically resected with a favourable result as described in this article.Histopathologically, the isolated lesion consisted of laminated squamous propria and muscular tissue, the corneum of the epithelial tissue was fragible and the intercellular space markedly enlarged. Dysplasia was observed in the granular layer, spinal layer and basal layer, however, the basal layer was distinct with no evidence of cancer cell or infiltration. In the lamina propria, dilated capillary vessels and severe infiltration of small round cells mainly including plasma cells were found. The basal membrane was maintained normally and no lesion was noticed around the resected site. No recurrence tendency is now observed 3 years and 5 months after operation.

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.

The morphology and distribution of various types of intercellular junctions were investigated in young odontoblasts. Gap junctions were found between odontoblasts as well as between odontoblasts and fibroblasts in the dental pulp. The junctions between odontoblasts were larger and more numerous than those between odontoblast and fibroblast, suggesting that the former may play an important role in regulating cellular activity and the latter may provide a pathway of low electrical resistance between odontoblast and nerve fibres. Irregularly-shaped gap junctions appeared as small aggregations of particles associated with a particle-free area and may indicate that the junction might not yet have been completely assembled. Tight junctions were observed at the distal ends of the young odontoblasts, arranged to form small maculae or faciae occludentes rather than belt-like zonulae. It is therefore not likely that the junction contributes to barrier function in the young odontoblasts. Although structures resembling typical desmosome were recognizable, this type of junction in odontoblasts is properly termed a desmosome-like junction from its morphological peculiarities.

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.

A new method for obtaining statically admissible states of stress in plane strain in the mathematical theory of plasticity is presented. After deriving a general solution, the proposed procedure is exemplified by a known solution of a thick circular cylinder subjected to internal pressure. The method is applied to a thick circular cylinder subjected to internal pressure and shear, and a lower-bound solution is given.

This report contains a statistical study of 874 cases of epulis diagnosed by the Department of Pathology of Tokyo Dental College from 1966 to 1986. 1. Of the 874 cases, 344 were epulis fibrosa, 217 were epulis granulomatosa, 78 were epulis fibromatosa, 74 were epulis fibrosaosteoplastica, 51 were epulis hemangiomatosa, 43 were epulis fibrosa teleangiectaticum, 15 were epulis cementoplastica, 14 were epulis osteomatosa, 3 were congenital epulis, 2 were giant cell epulis, and 1 was epulis cementomatosa. 2. As has been reported in other literature, there is a marked tendency for this condition to occur in females (331 male cases and 539 female cases). 3. Our data indicate a higher occurrence rate in people in their fifties, although the occurrence rates were similar in people in their twenties and in people in their sixties. 4. The epulis was observed most frequently in the maxillary incisor region.

As reported in a companion paper [1], quite a variety of crystalline and amorphous polymers were hydrostatically extruded with extrusion ratios ranging from 1.2 to 10, and a linear relation was obtained between the extrusion pressure p and extrusion ratio R. Buckley and Long have hydrostatically extruded polyethylene, polypropylene, and some other polymers and have also obtained a linear relation between p and R [2]. The linear relation between p and R was also established by Davis for polyethylene [3], and by Yoon et al. for polypropylene [4]. Nakayama and Kanetsuna [5], on the other hand, hydrostatically extruded polyethylene at various levels of temperature and obtained an exponential relation between p and R. Recently, Nakayama et al. [6] also established a nonlinear relation for polypropylene.

A new synthetic pyrethroid, permethrin, has recently been granted a registration by the United States Environmental Protection Agency. Permethrin and a large number of other chemicals of its type are expected to receive widespread use in the environment in the near future. Since the mechanism by which these compounds exert their toxic effect in insects (and at higher doses in mammals) is by disruption of the normal function of nervous tissue, a detailed morphologic evaluation of the nervous system was performed on rats from two long-term feeding studies conducted on permethrin. In this evaluation, examination of central and peripheral nervous plus examination of extensive morphometric data and teased myelinated fibers of distal sural and tibial nerves and of the maxillary division of cranial nerve V did not reveal any changes which could be attributed to the feeding of the pesticide.

Ten engineering polymers, crystalline or amorphous, were hydrostatically extruded in castor oil at pressures up to 4 kbars without heating the pressure vessel [1]. The polymers studied included polyethylene, polypropylene, nylon 6, polyoxymethylene, polyvinyl chloride, acryronitrile-butadiene-styrene copolymer, polymethyl methacrylate, polycarbonate, polystyrene, and epoxy. The extrusion ratios studied ranged from 1.2 to 10.0. A linear relationship was experimentally established between the extrusion pressure and extrusion ratio within a certain limit of the latter. In addition, it was experimentally proved that the cross-sectional planes remained planes during the extrusion process when the reduction ratio was not very large [2].

Through X-ray and endoscopic examination of stomach, a 77 year-old man, who complained of epigastralgia, he was diagnosed to have Borrmann III type gastric carcinoma on the antrum. The gastric biopsy specimen obtained from the tumor revealed to be well differentiated adenocarcinoma. Since the patient refused receiving surgical treatment, a combined administration of futraful and uracil (UFT therapy) was performed. 4 weeks after receiving UFT therapy, the patient became less aware of subjective symptom and the gastrofiberscopic picture showed smaller mass lesion compared to that of prior to the treatment. 8 weeks later, the tumor was remarkable reducing its size. When compared 14 cases of gastric carcinoma receiving UFT therapy with 26 cases receiving Futraful therapy (FT therapy), the UFT group responded more effectively than the FT group. In the UFT therapy, complete (CR) and partial response (PR) were obtained in 4 of 13 cases of gastric carcinoma with an effective rate of 30.8% according to the response criteria proposed by the Koyama-Saitoh group and with a Karnofsky scale of IA or better in 6 (42.8%) of 14 cases. On the other hand, in the FT therapy CR and PR were obtained in 5 of 26 cases with that of 19.2%, while a Karnofsky scale of IA or better was achieved in 6 (23.1%). As for 3 cases of PR in the UFT therapy the microscopic view of the biopsy specimen from gastric carcinoma showed well differentiated adenocarcinoma, which responded to the UFT therapy remarkably 4-5 weeks after receiving UFT therapy.

Cells of dental pulp, periodontal ligament, bone marrow and muscle derived from the same rat were cultured in vitro. Outgrowth of cells from these four explants were examined using phase-contrast microscope, light microscope and scanning electron microscope. Furthermore, cell lengths were measured randomly from SEM photographs and growth curves were plotted by calculating cell numbers. These cells had different morphology in both shape and length. The bone marrow cells showed the most rapid proliferation rate followed by muscle, periodontal ligament and most slowly in dental pulp cells.

The purpose of the present study is to elucidate influences of diet on periodontal regeneration following experimental periodontitis in rats. S-D rats were divided into two groups, which were fed either a conventional diet (group A) or a sucrose-rich diet (group B). Experimental periodontitis was produced by placement of elastic bands between maxillary molar teeth. After one week, the elastic bands were removed and the animals were sacrified by perfusion fixation with formalin immediately, 1, 3, or 5 days, or 1, 2, 3, 4, 6, or 8 weeks after the removal. Sections of the teeth and surrounding tissue were examined by light microscopy. Three days after the removal, in both groups, granulation tissues with many inflammatory cells were covered by epithelial cells; the attachment site to the root surface was located more apically than the cemento-enamel junction. Distinct periodontal pockets were formed by five days after the removal in group A. In group B, the infiltrations of inflammatory cells were more prominent than in group A. Six weeks after the removal in both groups, an epithelium which resembled long junctional epithelium rather than pocket epithelium became thicker. Eight weeks after the removal, the findings were similar to those of six weeks in group A. However, a severe inflammatory cell concentration was found in group B. These results suggest that periodontal wound healing is markedly influenced by diet, and that this experimental system is useful for studying dynamic changes in both pocket and long junctional epithelia.