Ichiroh Katsuumi

Differential expression and localization of WNTs in an animal model of skin wound healing

Wound healing is a dynamic process, and a variety of growth factors have a significant impact on the process. Although the WNT family has a multitude of effects on the state of various physiological pathways, the expression and role of WNT in wounded tissue have remained an enigma. The aim of this study was to assess the expression and localization of WNTs in a murine model of wound healing. RNA isolated from full‐thickness cutaneous wounds from day 1 to day 21 postwounding were subjected to reverse transcription‐polymerase chain reaction, and expression of WNT3, 4, 5a, and 10b were observed. Immunohistochemistry localized WNT10b to regenerating epithelial cells on day 1 and 3, and WNT4 on day 3 and 5. WNT4 also reacted with fibroblast‐like cells beneath the epithelium. The cytoplasmic staining of β‐catenin, a WNT signaling molecule, in the epithelial cells indicates an activation of the WNT signaling pathway. Among target genes downstream of the pathway, matrix metalloproteinases (MMPs) degrade and remodel the extracellular matrix during wound healing. Gelatin zymography showed that MMP9 was expressed from day 1 to day 5. MMP‐2 was continuously expressed, but maximally up‐regulated at day 5. Activation of MMP‐2 coincided with expression of membrane‐type 1 MMP, suggesting an involvement of WNTs in this proteolytic cascade. Therefore, WNTs may contribute to the process of wound healing in a spatiotemporal manner.

Clinical Investigation of Patients Who Develop Neuropathic Tooth Pain After Endodontic Procedures

INTRODUCTION This study aimed to determine the characteristics of patients with neuropathic tooth pain (NTP) who were selected from a group of patients who developed persistent pain after undergoing endodontic procedures. METHODS Of 271 patients who had chronic persistent pain that did not respond to previous endodontic procedures and were referred to the Endodontic Team of the Nippon Dental University Hospital, 16 patients (5.9%; mean age, 46.8 years; 13 women) who fulfilled the diagnostic criteria for NTP were recruited. The inclusion criteria for the patients were the presence of chronic persistent pain and other pain-related symptoms, despite the absence of major pathology. RESULTS Pain predominantly occurred in the maxilla (14 patients). In 10 patients (62.5%), NTP developed after retreatment. Daily application of tricyclic antidepressants produced pain relief in 11 patients (68.8%). CONCLUSIONS These results indicated that NTP is a rare type of chronic intractable endodontic pain and that careful diagnosis of NTP is important.

Tooth-pulp-evoked rostral spinal trigeminal nucleus neuron activity is inhibited by conditioning sciatic nerve stimulation in the rat: possible role of 5-HT3 receptor mediated GABAergic inhibition.

The purpose of the present study was to determine whether modulation of the trigeminal spinal nucleus oralis (TSNO) neurons related to tooth-pulp (TP)-evoked jaw-opening reflex (JOR) after electrical stimulation of the sciatic nerve (SN) is mediated by the descending serotonergic (5-HT(3)) inhibitory system activated by inhibitory GABAergic interneurons. In 30 anesthetized rats, the activity of TSNO neurons (87.5%, 35/40) and all digastric muscle electromyograms (dEMG, n=30) in response to TP stimulation (at an intensity of 3.5 times the threshold for JOR) were inhibited by conditioning stimulation of the SN (5.0 mA x 0.5 ms, 1 Hz, conditioning-test intervals; 50 ms). The inhibitory effects were significantly attenuated after intravenous administration of the 5-HT(3) receptor antagonist ICS 205-930 (n=6). Using multibarrel electrodes, iontophoretic application of ICS 205-930 into the TSNO significantly reduced the SN stimulation-induced inhibition of TP-evoked TSNO neuronal excitation (n=6), and in the same neurons, iontophoretic application of the GABA(A) receptor antagonist bicuculline into the TSNO greatly inhibited their effect. On the other hand, we found the expression of 5-HT(3) receptor immunoreactive neurons in the TSNO. These results suggest that SN stimulation may activate the descending serotonergic (5-HT(3)) inhibitory system through activation of inhibitory GABAergic interneurons, which inhibit excitatory responses of the TSNO neurons to TP stimulation.

Tooth-pulp-evoked rostral spinal trigeminal neuronal excitation is attenuated by the activation of 5-HT3 receptors via GABAergic interneurons in the rat

The effect of iontophoretic application of the 5-HT3 receptor agonist, phenylbiguanide (PBG), on the excitation of the trigeminal spinal nucleus oralis (TSNO) neurons to tooth-pulp (TP) stimulation was examined. The PBG application inhibited the TP-evoked TSNO neuronal excitation, and this inhibition was completely blocked by co-application of a GABAA receptor antagonist, bicuculline. The results suggest that the activation of 5-HT3 receptors elicits GABA release in the TSNO.

Comparison of the bond strength of composite resin to Er:YAG laser-irradiated enamel/dentin pre-treated with various methods

Abstract The purpose of this study was to compare the effects of pre-treatment on bond strength between composite resin and Er:YAG laser-irradiated enamel/dentin. The Er:YAG laser was irradiated on 60 extracted human teeth at following conditions; for enamel: 200 mJ/4 Hz, total energy 30 J, for dentin: 100 mJ, total energy 15 J. The irradiated 60 teeth were divided into six groups (n=5); Gr.1: ground with silicon carbide paper; Gr.2: laser was irradiated at foregoing condition; Gr.3: 37% phosphoric acid was applied to irradiated surface; Gr.4: ultrasonic scaler was applied to irradiated surface; Gr.5: air scaler was applied to irradiated surface; Gr.6; air-powder polisher applied to irradiated surface. SE bond and AP-X (Kuraray) were applied and cured. Tensile bond strengths (TBS) were measured after 24 h. The data were analyzed using ANOVA and Sheffes-tests. TBS of dentin was significantly higher than that of enamel. Significant differences among Gr.1 and 2, 3, 4, 5, Gr.2 and 3,4,5,6, Gr.3 and 6, Gr.4 and 6, Gr.5 and 6 were observed. The application of air-powder polisher for Er:YAG laser-irradiated enamel/dentin was effective to obtain high TBS.