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Biomedical subjects

Y Sakakura

Publications and source records attributed to Y Sakakura.

At least 181 records · Page 10Linked to original sources
PubMed1988

Influence of 1,25-dihydroxyvitamin D3 on cell proliferation during odontogenesis of the mouse embryonic molars in vitro.

Mandibular first molars from 17-day-old mouse embryos were cultured for 2 and 4 days in alpha-MEM supplemented with 10% newborn bovine serum containing 0.02% ethanol or 0.1, 1.0 or 10 ng/ml 1,25-(OH)2D3. After embedding, every 6th section was stained and mitotic features of inner dental epithelium (IDE) and dental papilla cells (DP) were counted under a light microscope. On the 2nd day, no significant differences were observed in the IDE and DP mitotic indexes among the control, ethanol, and the three vitamin D groups. On the 4th day, the indexes for all groups decreased. But the IDE indexes for all vitamin D groups were significantly different from those for the control (P less than 0.01) and ethanol (P less than 0.05) groups, whereas the DP index was significant (P less than 0.05) only in the 10 ng/ml vitamin D group. The present results suggest that vitamin D3 may have an influence on cell proliferation of IDE and DP in mouse embryonic molars in vitro.

Animals↗
PubMed1988

Bactericidal activity of middle ear effusion on a single isolate of non-typable Haemophilus influenzae.

Bactericidal activity of middle ear effusion (MEE) from children with otitis media with effusion (OME) on one strain of non-typable Haemophilus influenzae was measured and was compared with that of normal human serum. H. influenzae culture negative MEEs had a bactericidal activity on one strain of non-typable H. influenzae (P less than 0.01), and the activity of serous effusions was significantly stronger than that of mucoid ones (P less than 0.01). The bactericidal activity of 20% pooled MEE was almost equal to that of 4% normal human serum. Heat treatment (56 degrees C, 30 min) abolished this activity of both pooled MEE and normal human serum. Addition of fresh guinea pig serum (GPS) as a complement source to the heat-treated pooled MEE restored this activity, while its addition to the heat-treated normal human serum failed to do so. These results suggest that complement factor is important in the bactericidal activity of MEE.

Adolescent↗
PubMed1988

Interaction of bacteria with the immune system of Waldeyer's ring in otitis media with effusion.

An in vitro assay was used to study the adherence of Haemophilus influenzae (HI) to human nasal, nasopharyngeal, and buccal mucosal cells from patients with otitis media with effusion (OME). Adherence of unencapsulated HI was stronger than that of type b HI. HI adherence to both nasal and nasopharyngeal mucosal cells is stronger than that of buccal ones, indicating the presence of an important route of HI infection from the nose to the nasopharynx in OME. Specific antibodies against outer membrane vesicles (OMV) of HI were also examined using enzyme-linked immunosorbent assay. No significant correlation could be observed between specific secretory IgA or IgG titers and HI adherence to the nasopharyngeal mucosal cells, which suggests that HI adherence to the mucosal cells seems to depend on various factors including the local immunological defense system in OME patients. Anti-OMV IgA antibody producing cells were identified in the adenoid using the three-step immunoperoxidase method. These results suggest that non-typable strains of HI adhere more readily to epithelial cells and consequently are better suited to colonize the nasopharynx or to cause local infections.

Adolescent↗
PubMed1988

[Continuous superselective intra-arterial infusion with BUdR and 5 FU in combination with radiotherapy in the treatment of head and neck tumors].

Since 1984, a new method for intra-arterial administration of anti-cancer drug and radiosensitizer, named 'superselective continuous intra-arterial infusion therapy' has been used in combination with simultaneous irradiation, for the treatment of 67 patients with the head and neck tumors. Under fluoroscopy, a preshaped catheter was introduced retrogradely from the superficial temporal artery and inserted superselectively into the main feeding artery of the tumor. Through this catheter, continuous intra-arterial infusion chemotherapy was done. The primary therapeutic effects were appreciated as complete or partial response in all cases. It was considered that this method was more effective and with less adverse reactions for the treatment of the head and neck tumors compared with the conventional method.

Bromodeoxyuridine↗
PubMed1987

Distinct types of encapsulated sensory corpuscles in the oral mucosa of the dog: immunohistochemical and electron microscopic studies.

The types, structure, and distribution of encapsulated sensory endings that have lamellar investments in the oral mucosa and vermilion border of the lip of adult dogs were studied by light and electron microscopy. Immunohistochemistry for cholinesterase was used to identify the corpuscules by light microscopy. Two different types of corpuscular end-organs containing definite inner cores were distinguished. One was a typical, simple corpuscle, which contains only one, but sometimes two, inner cores composed of densely piled cytoplasmic lamellae surrounding a central axon terminal. The other type was characterized by the coexistence of convoluted inner cores, arborized free endings, and thin nerve bundles within a perineural capsule; we term this type "compound corpuscle." The ultrastructure of the inner cores in compound corpuscles was similar to that of mature, simple corpuscles. The arborized free endings in the compound corpuscles usually contained an accumulation of mitochondria and small clear vesicles. The compound corpuscles were frequently encountered in the vermilion border of the lip and in the labial and buccal mucosae but were rare in the masticatory mucosa of the gingiva and hard palate. From the results, it was concluded that the compound corpuscle is a distinct type of the sensory end-organ containing inner cores.

Animals↗
PubMed1987

Effects of parathyroid hormone on odontogenesis of the mouse embryonic molar tooth in vitro.

Mandibular first molars of 17-day-old mouse embryos were cultured in vitro to examine the histological effects of various concentrations of parathyroid hormone (PTH) on odontogenesis of the molars. PTH did not affect the cytodifferentiation of mesenchymal cells into preodontoblasts but inhibited that of preodontoblasts into odontoblasts. Consequently, the odontoblasts failed to undergo dentinogenesis. On the other hand, inner enamel epithelium achieved terminal cytodifferentiation into secretory ameloblasts and these cells partially formed enamel in spite of the absence of dentin. All treated molars showed the same histological disturbances and these effects were independent of PTH dose. The present study indicated that PTH had an influence on mesenchyme-derived cells, inhibiting both the differentiation of odontoblasts and the formation of predentin and dentin.

Ameloblasts↗
PubMed1987

The development of mandibular molar tooth germs isografted in the mouse spleen.

Tooth germs taken from 13-day-old embryonic mice and isografted in the spleen of adult mice were examined by light and electron microscopy. Well-organized tooth structures from the early cap stage to fully developed and mineralized mature teeth were obtained up to day 60 after transplantation. Germs on day 2 were similar to those prior to the onset of grafting but reached the late cap stage of development on day 4. On day 6, enamel and dentine formation were initiated and inner enamel epithelium and dental papilla cells were polarized. On days 10-15, enamel-matrix secretion was completed and almost all ameloblasts had become resorptive enamel epithelium. India ink injected from the recipient caudal vein accumulated to the capillaries within the pulp throughout the newly-formed vessels. On day 20, defined root formation had begun but occasionally irregular and cellular osteodentine was formed in root areas. On day 30, transplants were covered with reduced enamel epithelium and acellular cementum was formed at the root areas together with rudimentary periodontal ligament fibres. Cellular cementum became thicker up to day 40. There was little evidence of cellular infiltration from recipient tissue up to day 60. The spleen seems to be a suitable site for transplantation of tooth germs.

Animals↗
PubMed1987

Ultrastructural observations on the intraodontoblastic collagen fibrils of the mouse tooth germs.

We examined electron-microscopically and histochemically the ultrastructural features of the intraodontoblastic collagen fibrils of the mouse. These collagen fibrils were most common in secreting odontoblasts (pre-odontoblasts) of the maturating stages. In such cells they were most numerous at the peripheral zone of the Golgi apparatus, and were sometimes seen in odontoblastic processes. Intraodontoblastic collagen fibrils also had morphological variations including a banded structure enclosed by limiting membranes of vacuoles, fusion with primary lysosomes, and an electron-dense material covering with a structure that was not banded. Study of acid phosphatase activity showed that these structural changes were caused by the degradation of intraodontoblastic collagen fibrils by lysosomes. The results of studies of the permeation of lanthanum nitrate and the alkaline phosphatase reaction showed that these collagen fibrils were separate from the extracellular matrix and that there was no phagocytosis of the odontoblasts.

Acid Phosphatase↗
PubMed1987

Nerve endings in the vermilion border and mucosal areas of the rat lip.

Organized mechanoreceptors in mucosae and vermilion borders of rat lower lips were studied by light and electron microscopy. Cholinesterase histochemistry was applied to whole-mount preparations of mucosae for the light and electron microscopic identification of mechanoreceptors. Three types of lamellated corpuscles (a simple corpuscle; a coiled, simple corpuscle; and a Meissner-like corpuscle), and a unique, organized, bush-like assembly of free nerve terminals were identified. The simple corpuscles were found exclusively in the vestibular mucosa facing the incisor teeth. In contrast, bush-like endings were confined to the vestibular mucosa and to the lateral, eminent mucosa that faced the diastema. Furthermore, coiled simple corpuscles and Meissner-like corpuscles were localized in the boundary zone between the vestibular and lateral eminent mucosae and in the vermilion border. From a functional viewpoint, it is of interest that different areas of the rat lip contain different morphological patterns of mechanoreceptors.

Animals↗