Kazuyoshi Higashi

Reactive oxygen species production in mitochondria of human gingival fibroblast induced by blue light irradiation

In recent years, it has become well known that the production of reactive oxygen species (ROS) induced by blue-light irradiation causes adverse effects of photo-aging, such as age-related macular degeneration of the retina. Thus, orange-tinted glasses are used to protect the retina during dental treatment involving blue-light irradiation (e.g., dental resin restorations or tooth bleaching treatments). However, there are few studies examining the effects of blue-light irradiation on oral tissue. For the first time, we report that blue-light irradiation by quartz tungsten halogen lamp (QTH) or light-emitting diode (LED) decreased cell proliferation activity of human gingival fibroblasts (HGFs) in a time-dependent manner (<5 min). Additionally, in a morphological study, the cytotoxic effect was observed in the cell organelles, especially the mitochondria. Furthermore, ROS generation induced by the blue-light irradiation was detected in mitochondria of HGFs using fluorimetry. In all analyses, the cytotoxicity was significantly higher after LED irradiation compared with cytotoxicity after QTH irradiation. These results suggest that blue light irradiation, especially by LED light sources used in dental aesthetic treatment, might have adverse effects on human gingival tissue. Hence, this necessitates the development of new dental aesthetic treatment methods and/or techniques to protect HGFs from blue light irradiation during dental therapy.

Electron-Microscopic Observations of the Alveolar Brush Cell of the Rat

The alveolar brush cells in the rat lung were observed by transmission electron microscopy. The general structural features of the brush cells in this report were basically in agreement with earlier descriptions. However, this report is the first to detect long, thick microvilli with a unique form protruding into the alveolar lumen in parallel with the basement membrane, not vertically to the basement membrane. Moreover, intranuclear inclusions in the nucleus were observed for the first time in the alveolar brush cells in this study.

S100-immunoreactive cells contacting with rat mesencephalic trigeminal neurons

reduced by administration of the intracellular Ca2+ store depletor, thapsigargin or IP3 receptor antagonist, 2-APB. Therefore, these Ca2+ rhythms were not induced by action potential, and mainly due to Ca2+ release from an intracellular Ca2+ store (i.e. endoplasmic reticulum) via IP3 receptor.Activation of some kind of metabotropic receptors induces the Ca2+ release from an intracellular Ca2+ store. It was reported that metabotropic glutamate receptor type 5 (mGluR5) was one of therapeutic targets for Parkinson’s disease. Thus, we investigated effects of mGluR5 on the spontaneous Ca2+ rhythms. Antagonist of mGluR5, MPEP, suppressed the spontaneous Ca2+ rhythms. Thus, mGluR5PLC-IP3 signal cascade might be concerned with the Ca2+ rhythms. This result suggested that mGluR5 might contribute to the information processing in striatum by means of regulating intracellular Ca2+ concentration. Research fund: JST, CREST.

Glial cells with S100-like immunoreactivity in the rat trigeminal motor nucleus

Cilia are evolutionary conserved organelles that are classified into either conventional (motile) or primary (nonmotile). Compared with the conventional cilia whose functions are well known, the physiological function and significance of primary cilia are largely unknown, except for its pivotal role in early vertebrate development. Recent studies have shown that primary cilia brought together receptors and signal transduction components, such as Wnt and Hedgehog (Hh) signaling pathway. Although previous studies have shown that molecules for Hh signaling cascade are active in various cells during development, their physiological functions in the nervous system, especially in glial cells, are still enigmatic. In this study, we identified primary cilia in several types of glial cells. Moreover, Hh signaling molecules were accumulated on the primary cilia. Our studies indicate that Hh signaling via primary cilia playa an important role in proliferation and survival of glial cells under stressed condition of the cell.

Serotonin-immunoreactive Epithelial Cells in the Main Excretory Ducts of Rat Submandibular Glands

Although several morphological studies of main excretory duct of the submandibular gland have been performed, few reports present immunohistochemical data. Some epithelial cells or basal cells contain dense granules of an array shape by electron microscopic observation. However, the details of granulated cells have not been clarified immunohistochemically. In this study, both protein gene product 9.5 (PGP 9.5) and chromogranin or serotonin immunoreactive cells in the main excretory duct (MED) of the rat submandibular gland were observed. Some nerve endings were also observed among the epithelium of the MED. Therefore, the modifying mechanism of primary saliva in the MED may be regulated by both serotonergic nerve and endocrine cells with serotonin.

Ultrastructural Changes of Single Cilia in the Junctional Epithelium Following Application of Protease.

付着上皮は外的要因に対して生体防御機構を示すことが知られているが, 炎症の初期段階における細胞応答に関して不明な点が多い。そこで従来より他の器官・組織でその存在が報告され, 感覚もしくは化学受容器と類推されている孤立線毛に着目し, 健康な付着上皮と炎症初期における付着上皮中の孤立線毛の動態を形態学的に観察し, 付着上皮の機能解明を試みた。ラットの上頸右側第1臼歯口蓋側歯肉溝に細菌性プロテアーゼを塗布し, 初期炎症を惹起させたものを実験群として用いた。対照群として, 上頸左側第1臼歯口蓋側歯肉溝に生理食塩水を塗布したものを用いた。実験期間は, 塗布1, 3, 5日間とし, それぞれ電子顕微鏡にて観察した。観察対照部位は付着上皮及び歯肉溝上皮とした。その結果, 付着上皮において対照群では孤立線毛の分布は全層にわたって認められたが, 実験群では漸次消失した。また歯肉溝上皮では対照群と実験群では差異は認められなかった。以上の結果より対照群と実験群では, 孤立線毛の分布に差異が認められた。これらのことから孤立線毛が感覚受容器もしくは化学受容器として初期炎症に何らかの関係を有していることが示唆された。