Tetsuo Shirakawa - Academia.edu (original) (raw)
Papers by Tetsuo Shirakawa
Oral Diseases, 2010
Injection of complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) caus... more Injection of complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) causes acute swelling around the joint and subsequent morphological alterations in the condyle. We aimed to evaluate changes in the three-dimensional architecture of the condyle induced with CFA. The CFA was injected into the unilateral TMJ of rats and morphological changes in the condyle were assessed repeatedly for 14 days by in vivo micro-CT. Osseous abnormalities of condyle were first observed at 3-5 days after CFA injection on the tomographic images, and the condylar deformation became more obvious thereafter. Among 12 condyles examined at 14 days postinjection, osteophytosis was observed in all of the specimens and bone erosion coexisted in five condyles. None of the saline-treated condyles showed architectural changes. Significant changes were detected in the mesiolateral and rostrocaudal widths of the CFA-treated condyles at 10-14 days postinjection (P < 0.01). The extent of both condylar bone formation and resorption was greater in the CFA-injected TMJs than in saline-injected TMJs (P < 0.05). These results indicate that CFA causes dynamic morphological changes in the condyle and that our experimental approach will provide new insights into the subacute inflammatory processes in the TMJ.
Dentomaxillofacial Radiology, 2009
Our aim was to investigate the diagnostic accuracy of in vivo micro-CT for osseous abnormalities ... more Our aim was to investigate the diagnostic accuracy of in vivo micro-CT for osseous abnormalities of the rat temporomandibular joint (TMJ) condyle, using macroscopic observations as the "gold standard". A 30 TMJ arthritis model was prepared by injecting inflammatory complete Freund's adjuvant (CFA) into one side of the TMJ cavities of rats. The TMJ condyles were then imaged using micro-CT. The samples were macroscopically evaluated for osseous abnormalities, including erosions, osteophytes, flattening and concavity. The micro-CT images were independently assessed for abnormalities using the same criteria. Images in three planes were produced using the micro-XYZ technique with the micro-CT equipment. According to the macroscopic observations, 26 of the 60 rat condyles showed osseous abnormalities. The micro-XYZ images detected abnormalities in 25 of the condyles. The condyle diagnostic accuracy of micro-CT was 0.98, the sensitivity was 0.96 and the specificity was 1.0. Good diagnostic results were obtained using micro-CT. It is therefore an effective technique for the evaluation of osseous abnormalities in the rat TMJ condyle.
International Journal of Dentistry, Apr 15, 2022
Background. Denosumab, a human monoclonal antibody against receptor activator of nuclear factor-k... more Background. Denosumab, a human monoclonal antibody against receptor activator of nuclear factor-kappa B ligand (RANKL), is a novel bone antiresorptive agent used in patients with osteoporosis or metastatic bone cancer. Denosumab-related osteonecrosis of the jaw (DRONJ) has been recently reported in patients using denosumab. However, the mechanisms of DRONJ are not fully understood. Appropriate pathogenic mechanisms of DRONJ have yet to be established. erefore, we investigated the pathogenesis of DRONJ in mice. Methods. Anti-mouse RANKL monoclonal antibody and melphalan were performed to create a mouse model of DRONJ-like lesions in female C57BL/6J mice. We examined the development of DRONJ-like lesions and immune function. Results. We showed that administration of anti-mouse RANKL monoclonal antibody and melphalan caused DRONJ-like lesions that recapitulated major clinical manifestations of the human disease, including the characteristic features of an open alveolar socket and exposed necrotic bone. In the analysis using a mouse model of DRONJ-like lesion, it was revealed that anti-mouse RANKL monoclonal antibody and melphalan suppress autoimmune regulator (AIRE) expression in the thymus and imbalanced Tcell populations. Conclusion. is study suggests evidence of an immunity-based mechanism of DRONJ-like disease. is work may contribute to a better understanding of the pathogenesis of human DRONJ.
Clinical advances in periodontics, Jun 1, 2018
BackgroundOral inflammatory lesions assist in the diagnosis of certain systemic diseases that pri... more BackgroundOral inflammatory lesions assist in the diagnosis of certain systemic diseases that primarily affect other organs.MethodsA young girl, 3 years and 3 months old, presented with aphthous stomatitis, upper lip cheilitis, and swelling and bleeding of the upper gingiva. She had a medical history of repeated fever, skin tag of the anus, and constipation. Thus, it was suspected that her disease is a systemic disease with digestive symptoms. From clinical manifestation and endoscopy findings containing aphthoid ulcers in the bowel, she was diagnosed with very early‐onset Crohn's disease (CD). Immediately, mesalazine was started.ResultsAfter 1 month, the oral symptoms were dramatically improved, and her general condition stabilized.ConclusionsOral symptoms often precede the appearance of gastrointestinal lesions in young CD patients, and oral conditions worsen if the disease remains untreated. Thus, assessment of patients with intractable stomatitis from the viewpoint of CD may aid in rapid diagnosis and better prognosis.
PubMed, Dec 1, 1987
Post-natal manifestation of circadian rhythms was examined in individual rats in order to clarify... more Post-natal manifestation of circadian rhythms was examined in individual rats in order to clarify the manner in which pups' circadian oscillation entrained to the maternal circadian system. Ablation of the hypothalamic suprachiasmatic nucleus (SCN), a putative circadian pacemaker, completely eliminated the circadian rhythms of spontaneous locomotor activity and plasma corticosterone level in pregnant rats. However, all pups born to mothers whose SCN were lesioned at day 10 of gestation showed free-running circadian rhythms of plasma corticosterone level with similar phase angles after the 4th week of postnatal life. Strong positive correlations between the phases of circadian locomotor rhythm at the day of weaning and each free-running period (tau) were observed in blinded pups nursed under identical lighting schedule (LD). The fact suggests that the individual circadian oscillation was in phase on a certain day before the weaning. Mother-pups exchange under reversed lighting schedule (LD and DL) and nursing under 4-hourly restricted daily feeding (RF) indicated that nursing mother rat could essentially phase-set the circadian locomotor rhythm of blinded pups when the conditions during nursing were artificially modified. The weight of neonatal rats was measured every 4 hours from day 1 to day 3 and day 9 to day 10 after birth, and 4-hourly weight gains showed apparent circadian periodicity from day 2 of age. Under ad-lib feeding of mother rats, pups' weight mainly increased during daytime but the phase of weight rhythm shifted under RF corresponding to the feeding time of the mother. These findings suggest that the circadian oscillation underlying the spontaneous locomotor activity and plasma corticosterone level in rats has entrained to the maternal circadian system during fetal life, and nursing mother is capable of phase-setting the circadian oscillation of blinded pups probably through the rhythmicity of the lactation.
Biomedical research, 2015
The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human pr... more The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human primary/deciduous teeth. In this study, we examined dental pulp cells from root portion (root cells) of primary teeth without discernible root resorption and compared them with pulp cells from the crown portion (crown cells). Root cells and crown cells were characterized and compared to each other based on progenitor/MSC characteristics and on their generation efficiency of induced pluripotent stem (iPS) cells. Root cells and crown cells included cells manifesting typical progenitor/MSC properties such as osteogenic and adipogenic differentiation potential and clonogenicity. Interestingly, root cells showed a higher expression level of embryonic stem cell marker, KLF4, than crown cells. Moreover, the number of colony-forming unit-fibroblast and cell proliferation rate were higher for root cells than crown cells, and the efficiency of generating iPS cells from root cells was approximately four times higher than that from crown cells. Taken together, these results suggest that root cells from primary teeth show the MSC-like properties and thus could be a potent alternative source for iPS cell generation and the subsequent transplantation therapy.
Neuroscience Letters, Aug 1, 1994
The effect of glutamate (GLU) on the phase of the circadian neuronal firing rhythm of the rat sup... more The effect of glutamate (GLU) on the phase of the circadian neuronal firing rhythm of the rat suprachiasmatic nucleus (SCN) was examined in vitro. GLU application in late subjective night produces phase-advances whereas GLU applied in early subjective night produces either phase-delays or a bimodal peak in the firing rhythm that appears to be a combination of phase-advances and phase-delays. Optic chiasm (OC) stimulation, or exposure of animals to light just prior to sacrifice, produces phase-delays in early subjective night, and phase-advances in late subjective night. None of GLU, light and OC stimulation produces significant phasechanges during subjective day. The results indicate that GLU is the neurotransmitter of the retinohypothalamic tract.
Journal of Dental Research, Oct 12, 2015
Somatosensory information from the dental pulp is processed in the primary (S1) and secondary som... more Somatosensory information from the dental pulp is processed in the primary (S1) and secondary somatosensory cortex (S2) and in the insular oral region (IOR). Stimulation of maxillary incisor and molar initially induces excitation in S2/IOR, rostrodorsal to the mandibular incisor and molar pulp-responding regions. Although S1 and S2/IOR play their own roles in nociceptive information processing, the anatomical and physiological differences in the temporal activation kinetics, dependency on stimulation intensity, and additive or summative effects of simultaneous pulpal stimulation are still unknown. This information contributes not only to understanding topographical organization but also to speculating about the roles of S1 and S2/IOR in clinical aspects of pain regulation. In vivo optical imaging enables investigation of the spatiotemporal profiles of cortical excitation with high resolution. We determined the distinct features of optical responses to nociceptive stimulation of dental pulps between S1 and S2/IOR. In comparison to S1, optical signals in S2/IOR showed a larger amplitude with a shorter rise time and a longer decay time responding to maxillary molar pulp stimulation. The latency of excitation in S2/IOR was shorter than in S1. S2/IOR exhibited a lower threshold to evoke optical responses than S1, and the peak amplitude was larger in S2/IOR than in S1. Unexpectedly, the topography of S1 that responded to maxillary and mandibular incisor and molar pulps overlapped with the most ventral sites in S1 that was densely stained with cytochrome oxidase. An additive effect was observed in both S1 and S2/IOR after simultaneous stimulation of bilateral maxillary molar pulps but not after contralateral maxillary and mandibular molar pulp stimulation. These findings suggest that S2/IOR is more sensitive for detecting dental pulp sensation and codes stimulation intensity more precisely than S1. In addition, contra- and ipsilateral dental pulp nociception converges onto spatially closed sites in S1 and S2/IOR.
Oral Diseases, Apr 8, 2014
The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human pr... more The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human primary/deciduous teeth. In this study, we examined dental pulp cells from root portion (root cells) of primary teeth without discernible root resorption and compared them with pulp cells from the crown portion (crown cells). Root cells and crown cells were characterized and compared to each other based on progenitor/MSC characteristics and on their generation efficiency of induced pluripotent stem (iPS) cells. Root cells and crown cells included cells manifesting typical progenitor/MSC properties such as osteogenic and adipogenic differentiation potential and clonogenicity. Interestingly, root cells showed a higher expression level of embryonic stem cell marker, KLF4, than crown cells. Moreover, the number of colony-forming unit-fibroblast and cell proliferation rate were higher for root cells than crown cells, and the efficiency of generating iPS cells from root cells was approximately four times higher than that from crown cells. Taken together, these results suggest that root cells from primary teeth show the MSC-like properties and thus could be a potent alternative source for iPS cell generation and the subsequent transplantation therapy.
Neuroscience Research, Sep 1, 2011
Journal of Japanese Society for Laser Dentistry, 2012
YAG laser is useful in endodontic treatment compared with conventional methods, resulting in disi... more YAG laser is useful in endodontic treatment compared with conventional methods, resulting in disinfection of the root canal and elimination of smear layers including bacteria and debris. An irradiation tip for root canal treatment has been developed; it can be used to perform lateral ablation using 20％ power in the forward direction and 80％ power in the lateral direction. However, the relationship between energy loss and distance of the endodontic irradiation tip was unclear. The aim of this study was to evaluate irradiation energy loss with change in distance, using an Er:YAG laser apparatus (Erwin Ad-vErL, J. Morita, Kyoto) and irradiation tip (R200T, J. Morita, Kyoto). The laser sensor (LMP10LP, COHERENT Inc., Portland) was placed vertically or horizontally at the irradiation tip. The irradiation energy was measured three times using a laser power meter (Field Master-GS, COHERENT Inc., Portland). The distance between the irradiation tip and sensor was varied from 1.0 to 10.0 mm. Irradiation energy was found to be inversely proportional to distance. An energy change was not clearly observed with low energy irradiation (30 mJ) , however, a high energy (50 mJ and 70 mJ) setting has decrease of energy for influence distance. The lateral position was more greatly affected by the change in distance than the vertical position.
Journal of Japanese Society for Laser Dentistry, 2010
Laser treatment of tissue is likely to be more effective than conventional treatment if a suitabl... more Laser treatment of tissue is likely to be more effective than conventional treatment if a suitable wavelength for the treatment is chosen. However, it is not easy to confirm the effects because a laser' s effects are fine and not easy to evaluate, so some innovation is necessary. Additionally, if we compare laser treatment with the conventional method, we can confirm the features and problems of the conventional method, which may result in ideas for overcoming the problems. This laser study enabled us to not only identify the effects of the laser, but also to clarify the problems of conventional methods, thus yielding valuable data as evidence. Synergistic effects may also have a big impact for dental evolution. When deciding on treatment options, it is more important for patients to be able to see, compare and understand data rather than to receive merely an oral explanation. This will strengthen the relationship between doctor and patient. After over 10 years of basic study on how the clinical application of Er:YAG laser affects hard tissues, we have obtained interesting results on tooth vibration and the characteristics of the surface after Er:YAG laser ablation. This paper outlines the data and possibilities Er:YAG laser for dental support of children and patients with developmental disorders, and shows how the laser can create a better future for pediatric dental support.
Tissue & Cell, Feb 1, 2002
The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG)... more The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins involved in osteoclastogenesis. In this study, we investigated the expressions of RANKL and OPG in cultured human periodontal ligament cells derived from deciduous teeth (DPDL cells) and their roles in osteoclastogenesis. Northern blotting revealed that the OPG mRNA was down-regulated by application of 10 À8 M 1 alpha, 25(OH) 2 vitamin D 3 [1,25-(OH) 2 D 3 ] and 10 À7 M dexamethasone (Dex). In contrast, RANKL mRNA was up-regulated by the same treatment. Western blotting demonstrated a decrease in OPG following application of 1, 25-(OH) 2 D 3 and Dex. Tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNCs) were induced when DPDL cells were co-cultured with mouse bone marrow cells in the presence of 1,25-(OH) 2 D 3 and Dex. TRAP-positive MNCs increased significantly when the DPDL cells were co-cultured with bone marrow cells in the presence of anti-human OPG antibody together with 1, 25-(OH) 2 D 3 and Dex. These results indicate that PDL cells derived from deciduous teeth synthesize both RANKL and OPG and could regulate the differentiation of osteoclasts.
The Japanese Journal of Pediatric Dentistry, Sep 25, 1998
BMC Oral Health, Jun 28, 2022
Background: A brain abscess is a focal infection in which abscesses form in the brain. A brain ab... more Background: A brain abscess is a focal infection in which abscesses form in the brain. A brain abscess is a rare but fatal disease when rupture occurs into the ventricles. We report a case of multiple brain abscesses caused by a hematogenous infection from the apical periodontitis of deciduous teeth. Case presentation: The patient was a 7-years and 8-months-old male with congenital heart disease. The patient sought medical attention due to fever and headache, for which he was started on three antibiotics with a diagnosis of multiple brain abscesses. Given that apical periodontitis of deciduous teeth was strongly suspected as the source of the brain abscess, the deciduous teeth were extracted. Immediately after deciduous teeth extraction, the patient's headache and neurological symptoms disappeared. Conclusions: After teeth extraction, a clear shrinkage of the brain abscess was observed, and the patient was discharged from the hospital.
Pediatric Dental Journal, Dec 1, 2022
The Japanese Journal of Pediatric Dentistry, Dec 25, 2010
How does a disability affect oral health? Kids with disabilities need help with daily activities;... more How does a disability affect oral health? Kids with disabilities need help with daily activities; maintaining oral health is one of them. Children with disabilities are at a higher risk of oral health problems including:
American Journal of Physiology-regulatory Integrative and Comparative Physiology, Feb 1, 1987
Postnatal phase setting of pup circadian rhythm by nursing mother was examined in rats by mother-... more Postnatal phase setting of pup circadian rhythm by nursing mother was examined in rats by mother-pup exchange experiments. To know the effect of phase reversal of the nursing mother, pups were exchanged after birth so that a mother rat raised pups, half of which were born to her and the other half which came from a reversed mother, and activity onset and offset of pup locomotor rhythm were measured at weaning. Effects of litter size were also examined. Direct entrainment to light-dark cycles was excluded by blinding pups. In the unexchanged group, a strong positive correlation was detected between the phase of the circadian rhythm at weaning and the free-running period measured after weaning. The area covered by the 99% confidence interval of the regression line was used for the phase reference zone, and the circadian rhythm of an exchanged pup whose phase at weaning was located outside the reference zone was regarded as having been influenced by the nursing mother. The complete phase reversal occurred in two out of seven exchanged pups when litter size was relatively large (n = 5-7) and in 9 out of 11 when litter size was small (n = 2). It is concluded that the nursing mother rat is capable of phase setting the circadian locomotor rhythm of blinded pups. This maternal effect seems to be related to litter size.
Dentomaxillofacial Radiology, Jul 1, 2012
In general, no consensus has been reached regarding the diagnostic criteria for obstructive sleep... more In general, no consensus has been reached regarding the diagnostic criteria for obstructive sleep apnoea syndrome (OSAS) in children and the criteria for selecting treatment are inconsistent. Therefore, the craniofacial and pharyngeal airway morphology of OSAS in children who had undergone drug therapy (non-op group) and OSAS in children who had undergone both drug therapy and surgical therapy (adenotonsillectomy) (op group) were compared. The purpose of this study was to examine the effectiveness of craniofacial morphology and pharyngeal airway morphology analysis in the treatment of children with OSAS. Methods: The craniofacial and pharyngeal airway morphology of the control group, the non-op group and the op group were compared to examine the differences of each group. The comparison used Mann-Whitney's U test. Results: A comparison between the non-op and the op groups showed significant differences in the facial axis, mandibular plane angle, ramus plane to the SN (porion and orbit) point, point Pog (pogonion) to the McNamara line, anteroposterior dysplasia indicator (APDI), D-AD1 [the distance between the posterior nasal spine (PNS) point and the nearest adenoid tissue, measured along the PNS-Ba (basion) point plane], D-AD2 (the distance between the PNS point and the nearest adenoid tissue, measured along a line from the PNS point perpendicular to the S (sella turcica)-Ba point plane), upper pharynx and soft palatal length. The op group showed significantly lower values of APDI than the non-op group, indicating that the op group showed a significant occlusion of class II, and that the mandibular bone was positioned posteriorly relative to the maxillary bone. Conclusions: The op group showed a significant posterior position and backward rotation of the mandibular bone, stenosis of the nasopharyngeal airway and an elongated soft palate compared with the non-op group, and it was speculated that there was a high probability of the necessity of surgical therapy (adenotonsillectomy) when a morphological factor played a major role as a cause of obstructive sleep apnoea. We recommend craniofacial morphology analysis and pharyngeal airway morphology analysis in the diagnosis and treatment planning of OSAS children.
Oral Diseases, 2010
Injection of complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) caus... more Injection of complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) causes acute swelling around the joint and subsequent morphological alterations in the condyle. We aimed to evaluate changes in the three-dimensional architecture of the condyle induced with CFA. The CFA was injected into the unilateral TMJ of rats and morphological changes in the condyle were assessed repeatedly for 14 days by in vivo micro-CT. Osseous abnormalities of condyle were first observed at 3-5 days after CFA injection on the tomographic images, and the condylar deformation became more obvious thereafter. Among 12 condyles examined at 14 days postinjection, osteophytosis was observed in all of the specimens and bone erosion coexisted in five condyles. None of the saline-treated condyles showed architectural changes. Significant changes were detected in the mesiolateral and rostrocaudal widths of the CFA-treated condyles at 10-14 days postinjection (P < 0.01). The extent of both condylar bone formation and resorption was greater in the CFA-injected TMJs than in saline-injected TMJs (P < 0.05). These results indicate that CFA causes dynamic morphological changes in the condyle and that our experimental approach will provide new insights into the subacute inflammatory processes in the TMJ.
Dentomaxillofacial Radiology, 2009
Our aim was to investigate the diagnostic accuracy of in vivo micro-CT for osseous abnormalities ... more Our aim was to investigate the diagnostic accuracy of in vivo micro-CT for osseous abnormalities of the rat temporomandibular joint (TMJ) condyle, using macroscopic observations as the "gold standard". A 30 TMJ arthritis model was prepared by injecting inflammatory complete Freund's adjuvant (CFA) into one side of the TMJ cavities of rats. The TMJ condyles were then imaged using micro-CT. The samples were macroscopically evaluated for osseous abnormalities, including erosions, osteophytes, flattening and concavity. The micro-CT images were independently assessed for abnormalities using the same criteria. Images in three planes were produced using the micro-XYZ technique with the micro-CT equipment. According to the macroscopic observations, 26 of the 60 rat condyles showed osseous abnormalities. The micro-XYZ images detected abnormalities in 25 of the condyles. The condyle diagnostic accuracy of micro-CT was 0.98, the sensitivity was 0.96 and the specificity was 1.0. Good diagnostic results were obtained using micro-CT. It is therefore an effective technique for the evaluation of osseous abnormalities in the rat TMJ condyle.
International Journal of Dentistry, Apr 15, 2022
Background. Denosumab, a human monoclonal antibody against receptor activator of nuclear factor-k... more Background. Denosumab, a human monoclonal antibody against receptor activator of nuclear factor-kappa B ligand (RANKL), is a novel bone antiresorptive agent used in patients with osteoporosis or metastatic bone cancer. Denosumab-related osteonecrosis of the jaw (DRONJ) has been recently reported in patients using denosumab. However, the mechanisms of DRONJ are not fully understood. Appropriate pathogenic mechanisms of DRONJ have yet to be established. erefore, we investigated the pathogenesis of DRONJ in mice. Methods. Anti-mouse RANKL monoclonal antibody and melphalan were performed to create a mouse model of DRONJ-like lesions in female C57BL/6J mice. We examined the development of DRONJ-like lesions and immune function. Results. We showed that administration of anti-mouse RANKL monoclonal antibody and melphalan caused DRONJ-like lesions that recapitulated major clinical manifestations of the human disease, including the characteristic features of an open alveolar socket and exposed necrotic bone. In the analysis using a mouse model of DRONJ-like lesion, it was revealed that anti-mouse RANKL monoclonal antibody and melphalan suppress autoimmune regulator (AIRE) expression in the thymus and imbalanced Tcell populations. Conclusion. is study suggests evidence of an immunity-based mechanism of DRONJ-like disease. is work may contribute to a better understanding of the pathogenesis of human DRONJ.
Clinical advances in periodontics, Jun 1, 2018
BackgroundOral inflammatory lesions assist in the diagnosis of certain systemic diseases that pri... more BackgroundOral inflammatory lesions assist in the diagnosis of certain systemic diseases that primarily affect other organs.MethodsA young girl, 3 years and 3 months old, presented with aphthous stomatitis, upper lip cheilitis, and swelling and bleeding of the upper gingiva. She had a medical history of repeated fever, skin tag of the anus, and constipation. Thus, it was suspected that her disease is a systemic disease with digestive symptoms. From clinical manifestation and endoscopy findings containing aphthoid ulcers in the bowel, she was diagnosed with very early‐onset Crohn's disease (CD). Immediately, mesalazine was started.ResultsAfter 1 month, the oral symptoms were dramatically improved, and her general condition stabilized.ConclusionsOral symptoms often precede the appearance of gastrointestinal lesions in young CD patients, and oral conditions worsen if the disease remains untreated. Thus, assessment of patients with intractable stomatitis from the viewpoint of CD may aid in rapid diagnosis and better prognosis.
PubMed, Dec 1, 1987
Post-natal manifestation of circadian rhythms was examined in individual rats in order to clarify... more Post-natal manifestation of circadian rhythms was examined in individual rats in order to clarify the manner in which pups' circadian oscillation entrained to the maternal circadian system. Ablation of the hypothalamic suprachiasmatic nucleus (SCN), a putative circadian pacemaker, completely eliminated the circadian rhythms of spontaneous locomotor activity and plasma corticosterone level in pregnant rats. However, all pups born to mothers whose SCN were lesioned at day 10 of gestation showed free-running circadian rhythms of plasma corticosterone level with similar phase angles after the 4th week of postnatal life. Strong positive correlations between the phases of circadian locomotor rhythm at the day of weaning and each free-running period (tau) were observed in blinded pups nursed under identical lighting schedule (LD). The fact suggests that the individual circadian oscillation was in phase on a certain day before the weaning. Mother-pups exchange under reversed lighting schedule (LD and DL) and nursing under 4-hourly restricted daily feeding (RF) indicated that nursing mother rat could essentially phase-set the circadian locomotor rhythm of blinded pups when the conditions during nursing were artificially modified. The weight of neonatal rats was measured every 4 hours from day 1 to day 3 and day 9 to day 10 after birth, and 4-hourly weight gains showed apparent circadian periodicity from day 2 of age. Under ad-lib feeding of mother rats, pups' weight mainly increased during daytime but the phase of weight rhythm shifted under RF corresponding to the feeding time of the mother. These findings suggest that the circadian oscillation underlying the spontaneous locomotor activity and plasma corticosterone level in rats has entrained to the maternal circadian system during fetal life, and nursing mother is capable of phase-setting the circadian oscillation of blinded pups probably through the rhythmicity of the lactation.
Biomedical research, 2015
The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human pr... more The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human primary/deciduous teeth. In this study, we examined dental pulp cells from root portion (root cells) of primary teeth without discernible root resorption and compared them with pulp cells from the crown portion (crown cells). Root cells and crown cells were characterized and compared to each other based on progenitor/MSC characteristics and on their generation efficiency of induced pluripotent stem (iPS) cells. Root cells and crown cells included cells manifesting typical progenitor/MSC properties such as osteogenic and adipogenic differentiation potential and clonogenicity. Interestingly, root cells showed a higher expression level of embryonic stem cell marker, KLF4, than crown cells. Moreover, the number of colony-forming unit-fibroblast and cell proliferation rate were higher for root cells than crown cells, and the efficiency of generating iPS cells from root cells was approximately four times higher than that from crown cells. Taken together, these results suggest that root cells from primary teeth show the MSC-like properties and thus could be a potent alternative source for iPS cell generation and the subsequent transplantation therapy.
Neuroscience Letters, Aug 1, 1994
The effect of glutamate (GLU) on the phase of the circadian neuronal firing rhythm of the rat sup... more The effect of glutamate (GLU) on the phase of the circadian neuronal firing rhythm of the rat suprachiasmatic nucleus (SCN) was examined in vitro. GLU application in late subjective night produces phase-advances whereas GLU applied in early subjective night produces either phase-delays or a bimodal peak in the firing rhythm that appears to be a combination of phase-advances and phase-delays. Optic chiasm (OC) stimulation, or exposure of animals to light just prior to sacrifice, produces phase-delays in early subjective night, and phase-advances in late subjective night. None of GLU, light and OC stimulation produces significant phasechanges during subjective day. The results indicate that GLU is the neurotransmitter of the retinohypothalamic tract.
Journal of Dental Research, Oct 12, 2015
Somatosensory information from the dental pulp is processed in the primary (S1) and secondary som... more Somatosensory information from the dental pulp is processed in the primary (S1) and secondary somatosensory cortex (S2) and in the insular oral region (IOR). Stimulation of maxillary incisor and molar initially induces excitation in S2/IOR, rostrodorsal to the mandibular incisor and molar pulp-responding regions. Although S1 and S2/IOR play their own roles in nociceptive information processing, the anatomical and physiological differences in the temporal activation kinetics, dependency on stimulation intensity, and additive or summative effects of simultaneous pulpal stimulation are still unknown. This information contributes not only to understanding topographical organization but also to speculating about the roles of S1 and S2/IOR in clinical aspects of pain regulation. In vivo optical imaging enables investigation of the spatiotemporal profiles of cortical excitation with high resolution. We determined the distinct features of optical responses to nociceptive stimulation of dental pulps between S1 and S2/IOR. In comparison to S1, optical signals in S2/IOR showed a larger amplitude with a shorter rise time and a longer decay time responding to maxillary molar pulp stimulation. The latency of excitation in S2/IOR was shorter than in S1. S2/IOR exhibited a lower threshold to evoke optical responses than S1, and the peak amplitude was larger in S2/IOR than in S1. Unexpectedly, the topography of S1 that responded to maxillary and mandibular incisor and molar pulps overlapped with the most ventral sites in S1 that was densely stained with cytochrome oxidase. An additive effect was observed in both S1 and S2/IOR after simultaneous stimulation of bilateral maxillary molar pulps but not after contralateral maxillary and mandibular molar pulp stimulation. These findings suggest that S2/IOR is more sensitive for detecting dental pulp sensation and codes stimulation intensity more precisely than S1. In addition, contra- and ipsilateral dental pulp nociception converges onto spatially closed sites in S1 and S2/IOR.
Oral Diseases, Apr 8, 2014
The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human pr... more The existence of progenitor/mesenchymal stem cells (MSCs) was demonstrated previously in human primary/deciduous teeth. In this study, we examined dental pulp cells from root portion (root cells) of primary teeth without discernible root resorption and compared them with pulp cells from the crown portion (crown cells). Root cells and crown cells were characterized and compared to each other based on progenitor/MSC characteristics and on their generation efficiency of induced pluripotent stem (iPS) cells. Root cells and crown cells included cells manifesting typical progenitor/MSC properties such as osteogenic and adipogenic differentiation potential and clonogenicity. Interestingly, root cells showed a higher expression level of embryonic stem cell marker, KLF4, than crown cells. Moreover, the number of colony-forming unit-fibroblast and cell proliferation rate were higher for root cells than crown cells, and the efficiency of generating iPS cells from root cells was approximately four times higher than that from crown cells. Taken together, these results suggest that root cells from primary teeth show the MSC-like properties and thus could be a potent alternative source for iPS cell generation and the subsequent transplantation therapy.
Neuroscience Research, Sep 1, 2011
Journal of Japanese Society for Laser Dentistry, 2012
YAG laser is useful in endodontic treatment compared with conventional methods, resulting in disi... more YAG laser is useful in endodontic treatment compared with conventional methods, resulting in disinfection of the root canal and elimination of smear layers including bacteria and debris. An irradiation tip for root canal treatment has been developed; it can be used to perform lateral ablation using 20％ power in the forward direction and 80％ power in the lateral direction. However, the relationship between energy loss and distance of the endodontic irradiation tip was unclear. The aim of this study was to evaluate irradiation energy loss with change in distance, using an Er:YAG laser apparatus (Erwin Ad-vErL, J. Morita, Kyoto) and irradiation tip (R200T, J. Morita, Kyoto). The laser sensor (LMP10LP, COHERENT Inc., Portland) was placed vertically or horizontally at the irradiation tip. The irradiation energy was measured three times using a laser power meter (Field Master-GS, COHERENT Inc., Portland). The distance between the irradiation tip and sensor was varied from 1.0 to 10.0 mm. Irradiation energy was found to be inversely proportional to distance. An energy change was not clearly observed with low energy irradiation (30 mJ) , however, a high energy (50 mJ and 70 mJ) setting has decrease of energy for influence distance. The lateral position was more greatly affected by the change in distance than the vertical position.
Journal of Japanese Society for Laser Dentistry, 2010
Laser treatment of tissue is likely to be more effective than conventional treatment if a suitabl... more Laser treatment of tissue is likely to be more effective than conventional treatment if a suitable wavelength for the treatment is chosen. However, it is not easy to confirm the effects because a laser' s effects are fine and not easy to evaluate, so some innovation is necessary. Additionally, if we compare laser treatment with the conventional method, we can confirm the features and problems of the conventional method, which may result in ideas for overcoming the problems. This laser study enabled us to not only identify the effects of the laser, but also to clarify the problems of conventional methods, thus yielding valuable data as evidence. Synergistic effects may also have a big impact for dental evolution. When deciding on treatment options, it is more important for patients to be able to see, compare and understand data rather than to receive merely an oral explanation. This will strengthen the relationship between doctor and patient. After over 10 years of basic study on how the clinical application of Er:YAG laser affects hard tissues, we have obtained interesting results on tooth vibration and the characteristics of the surface after Er:YAG laser ablation. This paper outlines the data and possibilities Er:YAG laser for dental support of children and patients with developmental disorders, and shows how the laser can create a better future for pediatric dental support.
Tissue & Cell, Feb 1, 2002
The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG)... more The receptor activator of NF-kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG), are the important proteins involved in osteoclastogenesis. In this study, we investigated the expressions of RANKL and OPG in cultured human periodontal ligament cells derived from deciduous teeth (DPDL cells) and their roles in osteoclastogenesis. Northern blotting revealed that the OPG mRNA was down-regulated by application of 10 À8 M 1 alpha, 25(OH) 2 vitamin D 3 [1,25-(OH) 2 D 3 ] and 10 À7 M dexamethasone (Dex). In contrast, RANKL mRNA was up-regulated by the same treatment. Western blotting demonstrated a decrease in OPG following application of 1, 25-(OH) 2 D 3 and Dex. Tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (MNCs) were induced when DPDL cells were co-cultured with mouse bone marrow cells in the presence of 1,25-(OH) 2 D 3 and Dex. TRAP-positive MNCs increased significantly when the DPDL cells were co-cultured with bone marrow cells in the presence of anti-human OPG antibody together with 1, 25-(OH) 2 D 3 and Dex. These results indicate that PDL cells derived from deciduous teeth synthesize both RANKL and OPG and could regulate the differentiation of osteoclasts.
The Japanese Journal of Pediatric Dentistry, Sep 25, 1998
BMC Oral Health, Jun 28, 2022
Background: A brain abscess is a focal infection in which abscesses form in the brain. A brain ab... more Background: A brain abscess is a focal infection in which abscesses form in the brain. A brain abscess is a rare but fatal disease when rupture occurs into the ventricles. We report a case of multiple brain abscesses caused by a hematogenous infection from the apical periodontitis of deciduous teeth. Case presentation: The patient was a 7-years and 8-months-old male with congenital heart disease. The patient sought medical attention due to fever and headache, for which he was started on three antibiotics with a diagnosis of multiple brain abscesses. Given that apical periodontitis of deciduous teeth was strongly suspected as the source of the brain abscess, the deciduous teeth were extracted. Immediately after deciduous teeth extraction, the patient's headache and neurological symptoms disappeared. Conclusions: After teeth extraction, a clear shrinkage of the brain abscess was observed, and the patient was discharged from the hospital.
Pediatric Dental Journal, Dec 1, 2022
The Japanese Journal of Pediatric Dentistry, Dec 25, 2010
How does a disability affect oral health? Kids with disabilities need help with daily activities;... more How does a disability affect oral health? Kids with disabilities need help with daily activities; maintaining oral health is one of them. Children with disabilities are at a higher risk of oral health problems including:
American Journal of Physiology-regulatory Integrative and Comparative Physiology, Feb 1, 1987
Postnatal phase setting of pup circadian rhythm by nursing mother was examined in rats by mother-... more Postnatal phase setting of pup circadian rhythm by nursing mother was examined in rats by mother-pup exchange experiments. To know the effect of phase reversal of the nursing mother, pups were exchanged after birth so that a mother rat raised pups, half of which were born to her and the other half which came from a reversed mother, and activity onset and offset of pup locomotor rhythm were measured at weaning. Effects of litter size were also examined. Direct entrainment to light-dark cycles was excluded by blinding pups. In the unexchanged group, a strong positive correlation was detected between the phase of the circadian rhythm at weaning and the free-running period measured after weaning. The area covered by the 99% confidence interval of the regression line was used for the phase reference zone, and the circadian rhythm of an exchanged pup whose phase at weaning was located outside the reference zone was regarded as having been influenced by the nursing mother. The complete phase reversal occurred in two out of seven exchanged pups when litter size was relatively large (n = 5-7) and in 9 out of 11 when litter size was small (n = 2). It is concluded that the nursing mother rat is capable of phase setting the circadian locomotor rhythm of blinded pups. This maternal effect seems to be related to litter size.
Dentomaxillofacial Radiology, Jul 1, 2012
In general, no consensus has been reached regarding the diagnostic criteria for obstructive sleep... more In general, no consensus has been reached regarding the diagnostic criteria for obstructive sleep apnoea syndrome (OSAS) in children and the criteria for selecting treatment are inconsistent. Therefore, the craniofacial and pharyngeal airway morphology of OSAS in children who had undergone drug therapy (non-op group) and OSAS in children who had undergone both drug therapy and surgical therapy (adenotonsillectomy) (op group) were compared. The purpose of this study was to examine the effectiveness of craniofacial morphology and pharyngeal airway morphology analysis in the treatment of children with OSAS. Methods: The craniofacial and pharyngeal airway morphology of the control group, the non-op group and the op group were compared to examine the differences of each group. The comparison used Mann-Whitney's U test. Results: A comparison between the non-op and the op groups showed significant differences in the facial axis, mandibular plane angle, ramus plane to the SN (porion and orbit) point, point Pog (pogonion) to the McNamara line, anteroposterior dysplasia indicator (APDI), D-AD1 [the distance between the posterior nasal spine (PNS) point and the nearest adenoid tissue, measured along the PNS-Ba (basion) point plane], D-AD2 (the distance between the PNS point and the nearest adenoid tissue, measured along a line from the PNS point perpendicular to the S (sella turcica)-Ba point plane), upper pharynx and soft palatal length. The op group showed significantly lower values of APDI than the non-op group, indicating that the op group showed a significant occlusion of class II, and that the mandibular bone was positioned posteriorly relative to the maxillary bone. Conclusions: The op group showed a significant posterior position and backward rotation of the mandibular bone, stenosis of the nasopharyngeal airway and an elongated soft palate compared with the non-op group, and it was speculated that there was a high probability of the necessity of surgical therapy (adenotonsillectomy) when a morphological factor played a major role as a cause of obstructive sleep apnoea. We recommend craniofacial morphology analysis and pharyngeal airway morphology analysis in the diagnosis and treatment planning of OSAS children.