The mechanisms of neuropathic pain developed following peripheral nerve injury have not been fully elucidated. As to recent findings, the one of the pivotal mechanisms is thought to be glutamate toxicity of spinal cord neurons due to repetitive nerve stimulation originating from the injured region. Therefore, a possible way to clarify is a direct observation of spinal glutamate release evoked by peripheral nerve injury. In the present study, we examined whether enhanced cerebrospinal fluid glutamate (CSF-Glu) release leads to neuropathic pain in relation to neuronal damages after chronic constriction injury (CCI) in rats, by using spinal microdialysis technique. Regardingly, we confirmed a possibility that N-type Ca^<2+> channel blocker cilnidipine inhibits the CSF-Glu release accompanied with pain behaviour and cell damages. Male Sprague-Dawley rats were anesthetized with halothane and were intrathecally implanted with a loop-type microdialysis probe to detect CSF-aminoacids and PE 10 tube to inject cilnidipine, prior to following the experiments. Thereafter, the left sciatic nerve was loosely ligated according to the method by Bennett et.al (1988). Paw withdrawal latency (PWL) times of response to thermal stimulation were measured by planter testing before CCI followed by 3, 5, 7, and 10 days after CCI. Rats were separated into three groups. : 1) sham group 2) non-treated group (saline 10μl) 3) Cilnidipine group (cilnidipine 100ng/10μl). Each drug of 10μl was injected by PE10 tube everyday from 3 days after CCI. On day 5 and 10, microdialysis was conducted for measuring of CSF-Glu, taurine and serine by HPLC-ECD. After the microdialysis, perfusion fixation was performed under halothane anesthesia, and spinal cord tissue was removed following hematoxilin and eosin staining for assessment of neuronal necrosis with light microscope. The results showed that the responses to thermal stimulation to PWL in non-treated group were increased with time appearing from day 3 until day 10. On day 10, CSF-Glu release increased by 129% during the first 10 min and gradually declained to 116% during the next 10 min. Neuronal damage appeared specifically in Rexed III-IV with time. Cilnidipine ameliorated significantly the shortend PWL and the increased CSF-Glu release by thermal stimulation, and the neuronal damage in Rexed III-IV after CCI. Based on the present study, it is concluded that the increases in spinal glutamate release may initiate neuronal damage which leads neuropathic pain following nerve injury, in the dorsal horn of the spinal cord. In addition, it is suggested that beneficial effect of cilnidipine for developing neuropathic pain may be through mechanisms of inhibiting CSF-Glu release.

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On a case of distal extension removable partial prostheses with only six frontal teeth remaining, the wrought wire Akers clasp system has been usually used in expectation of the stress breaking action of flexible compornents because of an unfavorable prognosis. No plactical availability of this system, however, has been confirmed in vivo and in vitro too. The measurement device in six degree of freedom was utilized for revealing the effect of five types' lingual compornents of wrought wire Akers clasp system on the canine abutment movement, especially tipping movement. From this in vitro study the following conclusions could be drawn : 1) On comparing the tipping movement of each design with the design 1 as the control, no significant difference was found between any two designs regarding inclination of the abutment tooth. 2) The tipping direction of designs 2 and 4 with an ordinary lingual rest was mostly towards labial direction, but the inclination of designs 3 and 5 without an ordinary lingual rest, and design 1 considered as a specific type without an ordinary lingual rest and a reciprocal compornent such as a hook also was all towards lingual direction. 3) No significant difference was also recognized between the magnitude of inclination of the abutment tooth in crushing short type test food and that of the abutment tooth in crushing long type test food, although the latter inclination tended to be greater than the former one. 4) In comparing the magnitude of inclination of the working side abutment with that of the balancing side abutment tooth the former had a tendency to be greater excepting that of design 1, but there was no significant difference between the magnitude of inclination of either side. 5) Significant difference of ninety nine per cent confidence levels was recognized between tipping magnitude in unilateral loading and one in bilateral loading, and the latter was larger than the former. On the basis of the foregoing findings, the lingual compornent shapes of the wrought wire clasp systems has influence upon the canine abutment movement but the influence was found to be very small, especially on the magnitude of inclination. However, on tipping direction of the abutment tooth, the indicatioin was that it was influenced considerably in the same manner as that of cast Akers clasp systems.

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It has not yet been demonstrated as a conclusion whether or not the nerve fibers may play a role in developing a tumor. To clarify the relationship between DMBA-induced carcinoma of the gingiva and the nerve tissue, 42-day-old male Syrian golden hamsters (n=48) were used. After the left inferior alveolar nerve was cut at the mandibular foramen, the gingival surface at the lower first molar on both sides was scratched with a barbed broach. Subsequently, a 2.0% solution of DMBA in acetone was smeared with a small brush on the gingival surface three times a week until gross tumors were developed. At 0, 1, 4, 8, 12, 20, 22 and 24 weeks postoperatively, the animals were deeply anesthetized and perfused transcardially with isotonic saline followed by the modified Bouin solution for subsequent neurohistopathological examinations. The following results were obtained : 1. Tumor growth was observed in both the experimental and control groups. Macroscopically, the gingival surface with the nerve cut showed with time an elevation followed by ulceration, polyps, and exophytic type tumors with mixed features. Histologically, it indicated the nature of a carcinoma. 2. The tumors in the experimental group showed a faster development and a greater expansion than those in the control group. 3. As the mucous epithelium changed into carcinoma, nerve tissues were damaged by the tumor cells and the distibution of nerve fiber was decreased. However, regenerated nerve fibers were also found in the tumors of both groups. 4. The regenerated nerve fibers terminated in the intercellular space of the tumor cells and their stromal tissue in the experimental and control groups. 5. Endings of the regenerated nerve fibers in the tumor of the experimental and control groups were not of specific type, but free nerve endings. These results suggest that the gingival branch of the inferior alveolar nerve might exhibit some effects on the process of carcinogenesis, in addition to its original sensory function.

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p63はp53ファミリーの一員であり, 正常な胚発生に必須である.p63ノックアウトマウスでは, 四肢や上下顎の形成不全に加えて表皮や毛包, 乳腺, および歯など, 上皮間葉相互作用に依存する器官の発生が著しく阻害される.しかし, 正常な歯胚発生においてp63遺伝子産物の果たす役割については未だ十分に解明されていない.本研究の目的は, 免疫組織化学的手法を用いたp63タンパク検出の至適条件を求め, この条件を用いて歯胚の発生過程におけるp63タンパクの局在を解明することである.本研究では, 蕾状期(E13.5), 帽状期(E14.5)および鐘状期(E16.5)のマウス歯胚におけるp63タンパクの発現を, 免疫組織化学的手法を用いて検討した.ブアン固定, パラフィン包埋切片上での検出における前処理の必要性, および一次抗体の希釈濃度について検討した結果, クエン酸緩衝液を用いた熱処理を行い, 抗体を1 : 25に希釈した場合に最適な状態を得ることが分かった.また, 蕾状期歯胚では, 口腔上皮と歯胚上皮の基底膜に沿った細胞の核に, 帽状期では, 口腔上皮, 歯堤, 外エナメル上皮陽性反応が認められた.鐘状期では, 臼歯および切歯の口腔上皮, 歯堤, 外エナメル上皮に認められた.これらの結果は, p63タンパクが歯胚発生の開始期だけでなく, 蕾状期や帽状期, 鐘状期においても形態形成に関与していることを示唆する.

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