Hidehiro Kaya

Regulation of substance P release mediated via prejunctional histamine H3 receptors.

The involvement of the histamine H3 receptor in the regulation of substance P release in neurogenic inflammation was studied by using rat hindpaw skin. R-(-)-alpha-Methylhistamine, a specific histamine H3 receptor agonist, significantly inhibited the increased vascular permeability induced by antidromic electrical stimulation of the sciatic nerve in a dose-dependent manner at doses of 0.5-3 mg/kg (i.v.), and thioperamide (2 mg/kg i.p.), a specific histamine H3 receptor antagonist, prevented the inhibitory effect of R-(-)-alpha-methylhistamine. The antidromic stimulation also caused a significant increase in immunoreactive substance P release in the subcutaneous (s.c.) perfusate in the rat hindpaw. R-(-)-alpha-Methylhistamine (0.25-2 mg/kg) dose dependently inhibited the increase in release of immunoreactive substance P, and thioperamide (2 mg/mg i.p.) antagonized it. Perfusion of histamine (10(-3) M) elicited a significant increase of immunoreactive substance P release in the perfusate, which was reduced by R-(-)-alpha-methylhistamine and the antagonism of thioperamide was also observed. Histamine (in the presence of histamine H1 and H2 receptor antagonists) had an inhibitory effect on the electrically evoked release of immunoreactive substance P. These results strongly support the hypothesis that histamine regulates substance P release via prejunctional histamine H3 receptors that are located on peripheral endings of sensory nerves.

Role of substance P in neurogenic inflammation in the rat incisor pulp and the lower lip

Vascular permeability was significantly increased in the incisor pulp and skin of the lower lip in the rat after antidromic electrical stimulation of the inferior alveolar nerve, and this response was significantly inhibited by a substance-P antagonist. The content of substance P in the pulp and lip was also increased after stimulation. The permeability response was reduced by aspirin and bradykinin antagonists (both B1- and B2-receptor types) in the pulp and lip, indicating that prostaglandins and bradykinin may be involved. Mepyramine and methysergide inhibited the vascular response in the lip but not the pulp; the roles of histamine and serotonin differ in the two tissues. Injection of substance P into the incisor pulp and the lip skin caused dye leakage. This response was inhibited by pretreatment with compound 48/80 in the lip but not the pulp. Lip histamine content was decreased significantly after antidromic stimulation of the inferior alveolar nerve and pretreatment with compound 48/80, but was not changed in the pulp. The results suggest that substance P in the lip, after being released from the peripheral sensory-nerve endings, may act on the vascular system via histamine release from mast cells; but in the pulp may cause vascular response directly because of the scarcity of mast cells.

Preparation of Rat Gingival Mitochondria with an Improved Isolation Method

In order to establish a method of obtaining rat gingival mitochondria (Mt), Mt fractions were prepared in various combinations of homogenizing time with collagenase concentration. Rat gingival tissues were excised, minced, treated with collagenase, homogenized, and subjected to differential centrifugation rates. Both the respiratory control ratio (RCR) and adenosine diphosphate/oxygen (ADP/O) ratio of the Mt fraction prepared in a combination of 40, 50, or 60 sec homogenization with collagenase in a concentration range of 0.115%–0.130% (w/v) were measured. The values for the RCR and ADP/O ratio of the Mt fraction obtained in an optimal condition was 1.80 ± 0.05 and 1.65 ± 0.03, respectively. These results suggest that Mt of fairly high quality can be obtained through this refined combination of the homogenizing time and collagenase concentration.

Curing Furcation Involvement Caused by Bilateral Enamel Projections.

根分岐部病変は, 複根歯の根分岐部の歯周組織が崩壊している病的な状態を言う。複根歯は, 単根歯と比較すると形態が複雑であり, 歯周治療が困難となっている。これら根分岐部病変の原因は, 慢性辺縁性歯周炎の進行に伴うポケット形成, エナメル突起などの歯冠形態の異常, 歯髄疾患に起因する髄床底孔および側枝,不完全な歯内治療, 二次的な原因とされる咬合性外傷などが挙げられ, これらが単独あるいは複合することによって発症するとされている。根分岐部病変の原因の一つとされるエナメル突起は, 結合組織性付着を阻害し, そのためプラークが蓄積し歯周炎の進行によりアタッチメント・ロスが生じやすくなることから, Master & Hoskinsが3段階に分類した。また, 様々な原因によって引き起こされた根分岐部病変は, その進行状態をLindhe & Nymanが3段階にGrickmanが4段階に分類を提唱した。そこで, 今回臨床30%の高頻度に出現するエナメル突起が原因によって発症した両側下顎第一大臼歯の根分岐部病変に対して, モチベーション・初期治療を行い, 下顎左側第一大臼歯の根分岐部病変については, Lindhe & Nymanの分類2度であったため, Lindhe & Nymanの分類2～3度に基づいた処置を行った。一方, 下顎右側第一大臼歯の根分岐部病変については, Lindhe & Nymanの分類3度ではあるが, Lindhe & Nymanの分類1度を中心とした処置を行った結果, 良好な治癒経過が得られたので報告する。

Clinical Evaluation of Desensitizing Agent Containing Aluminum Chloride and Zinc Sulfate for Dentin Hypersensitivity.

塩化アルミニウムと硫酸亜鉛を主成分とする象牙質知覚過敏症治療剤 (BMD) の臨床応用を行い, その臨床的効果を市販の塩化亜鉛を主成分とする象牙質知覚過敏症治療剤と比較検討した。試験群および対照群の群内比較からは, 冷水痛, 冷気痛, 擦過痛のいずれの症状に関しても, ともに有意の改善が認められた。しかし, 群間比較では両群間で著明な差は観察されなかった。各症状の平均スコアーからの検討では, いずれの症状に関してもBMD塗布の試験群で塗布直後からより改善傾向が強いことが示唆された。薬剤塗布1週後に症状が消失した症例としなかった症例にわけて行った検討からも, 試験群でより改善傾向が強いことが示唆された。さらに臨床的有効性の検討から, 対照薬と比較してBMDでは冷水痛および冷気痛に対してより効果の高いことが示唆された。以上の成績より, BMDは象牙質知覚過敏症治療剤として臨床的に有効であることが強く示唆された。