Biomedical subjects

S Wakisaka

Publications and source records attributed to S Wakisaka.

At least 19 recordsLinked to original sources

PubMed2006

Early CT signs in patients with acute middle cerebral artery occlusion: incidence of contrast staining and haemorrhagic transformations after intra-arterial reperfusion therapy.

AIM: To investigate how often early computed tomography (CT) signs are associated with blood-brain barrier (BBB) disruption and result in haemorrhagic transformations. MATERIALS AND METHODS: Serial CT findings were prospectively evaluated in 61 patients with acute middle cerebral artery (MCA) occlusion who underwent initial CT examination within 3h of stroke onset and who were treated with intra-arterial reperfusion therapy within 6h of stroke onset. Obscuration of the margin of the lentiform nucleus and loss of the insular ribbon were evaluated as early CT signs in the deep MCA territories. Cortical effacement was also evaluated. BBB disruption was defined as contrast medium staining in post-therapeutic CT just after reperfusion therapy. The relationship between pre-therapeutic early CT signs and post-therapeutic contrast staining or haemorrhagic transformations was investigated. RESULTS: The frequency of early CT signs in the deep MCA territories was significantly higher than that of cortical effacement (68.9 versus 27.9%). There were significant correlations between pre-therapeutic early CT signs and post-therapeutic contrast staining in both the deep and superficial MCA territories. Compared with early CT signs in the deep MCA territories, cortical effacement had a significantly higher incidence of post-therapeutic contrast staining (54.8 versus 82.4%). Although not statistically significant, cortical effacement tended to develop into haemorrhagic transformations. There was no correlation between early CT signs in the deep MCA territories and haemorrhagic transformations. CONCLUSION: Cortical effacement may be an advanced CT sign with BBB disruption and potential risk for haemorrhagic transformations. The presence of early CT signs in the deep MCA territories may not be a contraindication of reperfusion therapy.

Acute Disease↗

PubMed2004

Spontaneous regeneration of the corticospinal tract after transection in young rats: a key role of reactive astrocytes in making favorable and unfavorable conditions for regeneration.

We demonstrated the occurrence of marked regeneration of the corticospinal tract (CST) after a single transection and failure of regeneration after a repeated transection in young rats. To provide convincing evidence for the complete transection and regeneration we used retrograde neuronal double labeling. Double-labeled neurons that took up the first tracer from the transection site and the second tracer from the injection site caudal to the transection site were observed in the sensorimotor cortex. The anterograde tracing method revealed various patterns of regeneration. In the most successful cases the vast majority of regenerated fibers descended in the normal tract and terminated normally whereas a trace amount of fibers coursed aberrantly. In the less successful cases fibers descended partly normally and partly aberrantly or totally aberrantly. To clarify the role of astrocytes in determining the success or failure of regeneration we compared expression of glial fibrillary acidic protein (GFAP), vimentin and neurofilament (NF) immunoreactivity (IR) in the lesion between single and repeated transections. In either transection, astrocytes disappeared from the CST near the lesion site as early as 3 h after lesioning. However, by 24 h after a single transection, immature astrocytes coexpressing GFAP- and vimentin-IR appeared in the former astrocyte-free area and NF-positive axons crossed the lesion. By contrast, after a repeated transection the astrocyte-free area spread and NF-positive axons never crossed the lesion. It appears likely that the major sign, and possibly cause of failure of regeneration is the prolonged disappearance of astrocytes in the lesioned tract area.

Animals↗

PubMed2001

Temporal and spatial distribution of Fos protein in the lumbar spinal dorsal horn neurons in the rat with chronic constriction injury to the sciatic nerve.

The temporal and spatial expression pattern of Fos protein in spinal dorsal horn neurons was examined by immunohistochemistry in rats with chronic constriction injury (CCI) to the sciatic nerve. In normal animals, a few Fos-immunoreactive (-IR) neurons were detected in the dorsal horn of the lumbar spinal cord. Following induction of CCI, a very large number of Fos-IR neurons appeared in the spinal dorsal horn, but a significant number of Fos-IR neurons were also observed in the contralateral dorsal horn where primary afferents of the injured sciatic nerve rarely project. Sham-operated animals also had a significant number of Fos-IR neurons in the dorsal horn bilaterally. The number of Fos-IR neurons reached its maximal level 1 day following placement of the ligatures (PO 1d). The ratio of the number of Fos-IR neurons in the ipsilateral dorsal horn to the contralateral dorsal horn, however, had its peak level 3 days following CCI (3.1-fold increase compared to the contralateral dorsal horn). The number of Fos-IR neurons in the dorsal horn gradually decreased, but increased again around PO 15d. On PO 30d, the number of Fos-IR neurons decreased and became comparable to that in normal animals. The present results indicate that the induction of Fos-IR neurons in the dorsal horn caused by CCI is biphasic and reaches its maximal level on PO 3d, near the time of hyperalgesia onset.

Animals↗

PubMed2001

Reduced expression of hepatocyte growth factor activator inhibitor type-2/placental bikunin (HAI-2/PB) in human glioblastomas: implication for anti-invasive role of HAI-2/PB in glioblastoma cells.

Hepatocyte growth factor activator inhibitor type-2/placental bikunin (HAI-2/PB) is a serine proteinase inhibitor that contains 2 Kunitz-domains and a presumed transmembrane domain. It has broad inhibitory spectra against various serine proteinases showing potent inhibitory activities not only to hepatocyte growth factor activator but also to plasmin, trypsin and kallikreins. In this study, we investigated the expression of HAI-2/PB in human gliomas in vivo and the effects of HAI-2/PB on the fibrinolytic and invasive capabilities of human glioblastoma cells in vitro. With RNA blot analysis, HAI-2/PB mRNA was expressed in normal brain and in low-grade astrocytomas, but was hardly detectable in anaplastic astrocytomas and glioblastomas, indicating that its expression levels were inversely correlated with the histological grade of human gliomas. To further explore the possible role of HAI-2/PB in glioma progression, cultured human glioblastoma cell lines (U251 and YKG-1) were transiently transfected with an expression vector harboring human HAI-2/PB cDNA. Subsequent analysis indicated that the expression of HAI-2/PB suppressed the fibrinolytic activities of both glioblastoma cell lines. Moreover, HAI-2/PB inhibited Matrigel invasion of U251 and YKG-1 cells by 30% and 64%, respectively. This anti-invasive effect appeared to be mediated primarily by the inhibitory activity of HAI-2/PB against the serine proteinase-dependent matrix degradation. These findings suggest that the reduced expression of HAI-2/PB is possibly involved in the progression of human gliomas.

Astrocytoma↗

PubMed2001

Temporal and spatial distribution of Fos protein in the parabrachial nucleus neurons during experimental tooth movement of the rat molar.

The present study was undertaken to reveal spatio-temporal changes in the distribution of Fos-like immunoreactive (-IR) neurons in the parabrachial nucleus (PBN), one of the important relay nuclei for processing autonomic and somatosensory information from the oro-facial regions, following the induction of experimental tooth movement in rat upper molars. The experimental tooth movement was induced by the insertion of elastic rubber between the first and second upper molars. In normal animals, the PBN contained a smaller number of Fos-IR neurons. Following experimental tooth movement, the Fos-IR neurons increased in number significantly on both the ipsilateral and contralateral PBN, reaching a maximum at 4 h (about 10 times that of normal animals), and then decreased gradually. However, a significant number of Fos-IR neurons remained at 24 h post-operation. Remarkable side-by-side differences in the number of Fos-IR neurons were recognized at 1 to 4 h following the experimental tooth movement. Their number returned to normal (basal) levels at 5 days post. All subnuclei of PBN showed similar temporal changes in the number of Fos-IR neurons, this being particularly apparent in lateral PBN. Administrations of morphine (3 and 10 mg/kg, i.p.) drastically reduced the induction of Fos-IR neurons in all subnuclei of both the ipsilateral and contralateral PBN in a dose-dependent manner, and its effect was antagonized by pretreatment with naloxone (2 mg/kg, i.p.). The reduction of Fos-IR neurons by morphine pretreatment suggests that the appearance of Fos-IR neurons in the PBN may be partly due to the noxious stimulation and/or stress arising from tooth movement. The bilateral expression of Fos-IR neurons in the PBN indicates that the experimental tooth movement causes the activation of PBN neurons for the processing of somatosensory as well as autonomic information. The prolonged expression of Fos-IR neurons in all the subnuclei of bilateral PBN reflects clinical features of the transient discomfort and/or abnormal sensations, which many patients often complain about during orthodontic treatment.

Afferent Pathways↗

PubMed2001

Development and maturation of taste buds of the palatal epithelium of the rat: histological and immunohistochemical study.

Palatal taste buds are intriguing partners in the mediation of taste behavior and their spatial distribution is functionally important for suckling behavior, especially in the neonatal life. Their prenatal development has not been previously elucidated in the rat, and the onset of their maturation remains rather controversial. We delineated the development and frequency distribution of the taste buds as well as the immunohistochemical expression of alpha-gustducin, a G protein closely related to the transduction of taste stimuli, in the nasoincisor papilla (NIP) and soft palate (SP) from the embryonic day 17 (E17) till the postnatal day 70 (PN70). The main findings in the present study were the development of a substantial number of taste pores in the SP of fetal rats (60.3 +/- 1.7 out of 122.8 +/- 5.5; mean +/- SD/animal at E19) and NIP of neonatal rats (9.8 +/- 1.0 out of 44.8 +/- 2.2 at PN4). alpha-gustducin-like immunoreactivity (-LI) was not expressed in the pored taste buds of either prenatal or newborn rats. The earliest expression of alpha-gustducin-LI was demonstrated at PN1 in the SP (1.5 +/- 0.5 cells/taste bud; mean +/- SD) and at PN4 in the NIP (1.4 +/- 0.5). By age the total counts of pored taste buds continuously increased and their morphological features became quite discernible. They became pear in shape, characterized by distinct pores, long subporal space, and longitudinally oriented cells. Around the second week, a remarkable transient decrease in the total number of taste buds was recorded in the oral epithelium of NIP and SP, which might be correlated with the changes of ingestive behaviors. The total counts of cells showing alpha-gustducin-LI per taste bud gradually increased till the end of our investigation (14.1 +/- 2.7 in NIP and 12.4 +/- 2.5 in SP at PN70). We conclude that substantial development of taste buds began prenatally in the SP, whereas most developed entirely postnatal in the NIP. The present study provides evidence that the existence of a taste pore which is considered an important criterion for the morphological maturation of taste buds is not enough for the onset of the taste transduction, which necessitates also mature taste cells. Moreover, the earlier maturation of palatal taste buds compared with the contiguous populations in the oral cavity evokes an evidence of their significant role in the transmission of gustatory information, especially in the early life of rat.

Animals↗

PubMed2001

The correlation between 99mTc-MIBI uptake and MIB-1 as a nuclear proliferation marker in glioma--a comparative study with 201Tl.

Technetium-99m methoxy-isobutylisonitrile (MIBI), like thallium-201 (201Tl), is a highly efficient agent for the diagnosis and monitoring of glioma tumors. Although 201Tl uptake is known to be partly associated with proliferative activity, little is known about the correlation between MIBI uptake and proliferation activity in gliomas. The current study was performed to assess the correlation between MIBI uptake and proliferative activities in gliomas, estimated by the monoclonal antibody to Ki-67 antigen (MIB-1) staining method. By comparing the results with those of 201Tl, we determined which tracer would be suitable for estimating proliferative activities. Twenty-four presurgical glioma patients (six with low-grade gliomas, five with anaplastic astrocytomas, and 13 with glioblastomas) were given MIBI and 201Tl SPECT. Early (10 min after injection) and delayed images (3 h after injection) were obtained for both MIBI and 201Tl scintigraphy. SPECT parameters, early ratio (ER), delayed ratio (DR), and retention index (RI) were obtained in both radiopharmaceuticals. All patients underwent subsequent surgical excision, and the specimens were immunostained for MIB-1. The proliferative activity was measured as a percentage positive nuclear area for MIB-1 (MI; MIB-1 index). To evaluate the relationship between the proliferative activity and SPECT parameters, we performed a correlation analysis. MI correlated with the MIBI uptake ratio (r = 0.75 for ER, and r = 0.7 for DR). Both DR and RI of 201Tl also correlated with MI, but weakly (r = 0.6 for DR, and. r = 0.59 for RI). There was no significant correlation between the MIB-1 index and the other parameters. MIBI-uptake parameters demonstrated a stronger positive correlation with the MIB-1 index than that of 201Tl. With the use of MIBI SPECT, we can estimate the proliferative activity of glioma noninvasively.

Adolescent↗

PubMed2001

Serial changes in signal intensities of the adjacent discs on T2-weighted sagittal images after surgical treatment of cervical spondylosis: anterior interbody fusion versus expansive laminoplasty.

BACKGROUND: There have been many reports about newly developed degenerative changes in the adjacent segments after anterior interbody fusion. It is a controversial issue whether the adjacent-segment disease in patients treated by anterior interbody fusion is the result of progressive cervical spondylosis at the adjacent levels or is caused by the arthrodesis. The aim of this study is to clarify the difference in postoperative effect on the adjacent segments between anterior interbody fusion and expansive laminoplasty. METHOD: This study included 14 patients who underwent pre- and postoperative MR images at 6 and 12 months. Seven patients underwent cervical interbody fusion and the other 7 patients underwent expansive laminoplasty. Disc degeneration was evaluated semiquantitatively by calculating the degenerative index (DI) that is a ratio of the intensity in the disc to that in the upper cervical cord. FINDINGS: In the anterior interbody fusion group, the adjacent disc intensities decreased within 12 months (F = 20.42; P < 0.01). The pre-operative mean DI was 0.59 +/- 0.16. The post-operative mean DIs were 0.56 +/- 0.16 at 6 months and 0.47 +/- 0.16 at 12 months. In the expansive laminoplasty group, the signal intensities of both the adjacent discs and the discs within the range of laminoplasty had no serial changes during the same period (F = 2.67; P = 0.09 and F = 0.15; P = 0.87 respectively). INTERPRETATION: Anterior interbody fusion had a significant influence on the adjacent discs even as soon as 12 months after surgery, but laminoplasty had no influence on them during the same period.

Adult↗

PubMed2001

Long-term enhancement of synaptic transmission induced by veratridine in rat CA3 hippocampal neurons.

Veratridine is a neurotoxin that induces persistent activation of sodium channels in excitable cells. We investigated the effects of this toxin on excitatory synaptic transmission in CA3 neurons of juvenile rat hippocampus using whole-cell patch-clamp and field-potential recordings. The population spikes evoked by electrical stimulation of the mossy fiber were gradually enhanced after washout of veratridine (0.3 microM), but they were not enhanced by the co-application of veratridine and an N-methyl-D-aspartate (NMDA) receptor antagonist (D-APV, 30 microM). When a pipette solution contained QX-314 that antagonized the effect of veratridine in the recorded neuron, oscillatory membrane depolarization appeared in the early stage during bath-application of veratridine and gradually decreased in the late stage. After washout of veratridine, however, the oscillatory depolarization was gradually restored and maintained for at least 3 h. This oscillatory depolarization was also abolished by D-APV. We suggest that the activation of NMDA receptors is involved in the veratridine-induced long-lasting enhancement in the excitatory synaptic transmission in rat CA3 hippocampal neurons.

2-Amino-5-phosphonovalerate↗

PubMed2001

Parenchymal hyperdensity on computed tomography after intra-arterial reperfusion therapy for acute middle cerebral artery occlusion: incidence and clinical significance.

BACKGROUND AND PURPOSE: The purpose of the present study was to assess the incidence and clinical significance of the intraparenchymal hyperdense areas on the posttherapeutic CT scan just after intra-arterial reperfusion therapy. METHODS: Seventy-seven patients with acute middle cerebral artery occlusion were studied prospectively with post-therapeutic CT. Hyperdense areas were classified into three groups: those in the lentiform nucleus, insular cortex and cerebral cortex. We investigated the incidence of hyperdense areas and hemorrhagic transformations and assessed whether location of hyperdense areas may play a role in the incidence of hemorrhagic transformations. We also evaluated correlation between early CT signs and hyperdense areas. RESULTS: Forty-five hyperdense areas were seen in 37 of the 77 patients (48.1%): 19 of the 45 (42.2%) were confirmed to be hematomas themselves, 6 (13.4%) showed later conversion to petechial hemorrhages, and 20 (44.4%) showed rapid disappearance without hemorrhagic transformations. Eleven of the 37 patients (29.7%) had neurological worsening due to massive hematoma (symptomatic hemorrhage), whereas none of the 40 patients without hyperdense areas had symptomatic hemorrhage. The incidence of hemorrhage among hyperdense areas was significantly lower in the insular cortex than in the other 2 regions (P<0.01). On the other hand, hyperdense areas in the lentiform nucleus had a significantly higher incidence of neurological worsening (P<0.05). There was a significant correlation between early CT signs and hyperdense areas (P<0.0001). CONCLUSIONS: The presence of hyperdense areas was a significant risk factor for severe hemorrhagic transformations, although only 29.7% of patients with hyperdense areas had symptomatic hemorrhage. On the contrary, the absence of hyperdense areas was a reliable negative predictor for symptomatic hemorrhage.

Acute Disease↗

PubMed2001

Differentiation of the lingual and palatal gustatory epithelium of the rat as revealed by immunohistochemistry of alpha-gustducin.

We used alpha-gustducin, a taste-cell-specific G protein to investigate the onset of taste transduction and its relation to the development of the palatal and lingual taste buds. Frozen cryostat and paraffin sections were prepared from the palatal and lingual gustatory epithelium of the rat from birth till postnatal day 21 (PN 21d). At PN 1-7d, alpha-gustducin-immunoreactive solitary ovoid or bipolar cells were scattered among the oral epithelium either horizontally along the oral surface or vertically oriented between the basal lamina and oral surface. In the circumvallate and foliate papillae, these cells became wrapped in alpha-gustducin-immunonegative cells surrounded by an extracellular space forming a bud-like structure. Simultaneously, different stages of typical taste buds were recognized, but alpha-gustducin was only expressed in some neonatally developed pored buds. At PN 1d, alpha-gustducin was expressed in pored taste buds with a relatively higher frequency recorded in the soft palate as compared with the nasoincisor, circumvallate, and foliate papillae. The immunoreactive cells were spindle shaped with elongated processes extending from the base to the pore of the taste buds. During the second week, the solitary cells could no longer be recognized while the total counts of immunoreactive cells within the taste buds gradually increased. We argue that taste transduction is essentially required from the time of birth and can be fulfilled by both of the solitary chemosensory cells, which are immunoreactive for alpha-gustducin and scattered in the oral epithelium, and the taste cells within the mature taste buds. Moreover, the onset of taste transduction accomplished by the palatal taste buds developed earlier than that achieved by taste buds in the circumvallate and foliate papillae.

Animals↗

PubMed2001

Large cholesterol granuloma arising from the frontal sinus--case report.

A 59-year-old male presented with a large cholesterol granuloma arising from the frontal sinus manifesting as a large, fluctuated, soft mass in his brow, compressing left eye. Skull radiography showed dilation of the frontal sinus. Computed tomography and magnetic resonance imaging revealed a cystic mass extending into the left orbit and anterior cranial fossa. Gross inspection at the frontal craniotomy showed mucinous, dark green fluid intermingled with shining material. The histological diagnosis was cholesterol granuloma with epithelial lining. Large cholesterol granuloma with facial deformity is always associated with bone and cosmetic problems. Wide opening of the frontal sinus followed by cyst wall removal and plastic repair of the skull is necessary.

Cholesterol↗

PubMed2001

Correlation of early CT signs in the deep middle cerebral artery territories with angiographically confirmed site of arterial occlusion.

BACKGROUND AND PURPOSE: Early CT signs in the deep middle cerebral artery (MCA) territories have been reported to be seen at the initial period of ischemia. We attempted to investigate the incidence of parenchymal hypodensity within 3 hours after ischemic onset among patients with angiographically proved embolic MCA occlusion and to assess the correlation of subtle hypodensity in the deep MCA territories with involvement of the lenticulostriate arteries in the presence of ischemia. METHODS: Fifty CT images obtained within 3 hours after onset of embolic MCA occlusion were retrospectively reviewed by three neurosurgeons who were aware of clinical features. Early CT signs in the deep MCA territories were divided into three grades according to their anatomic location: grade I, normal basal ganglia with hypodensity localized to the insula; grade II, partial obscuration of the posterolateral part of the putamen; and grade III, hypodensity of the entire lentiform nucleus. A grade I CT sign was considered to be a negative finding for lenticulostriate artery involvement, whereas grade II and III CT signs were considered to be positive findings. Site of occlusion and involvement of the lenticulostriate arteries were confirmed by angiography. RESULTS: Thirty-eight (76%) of 50 patients had early CT signs in the deep MCA territories. Sensitivity and specificity of a grade I CT sign indicating absence of lenticulostriate artery involvement in ischemia were 65% and 87%, respectively. On the other hand, sensitivity and specificity of grade II and grade III CT signs for presence of lenticulostriate artery involvement in ischemia were 77% and 100%, respectively. Grade II CT signs resulted from various sites of occlusion, whereas grade III was unequivocally predictive of proximal occlusion to all of the lenticulostriate arteries. CONCLUSION: Involvement of the lenticulostriate arteries may be presumed by precise evaluation of subtle, CT-revealed hypodensity in the deep MCA territories, even within 3 hours of ischemic onset.

Aged↗

PubMed2000

Expression of emmprin (CD147), a cell surface inducer of matrix metalloproteinases, in normal human brain and gliomas.

EMMPRIN (extracellular matrix metalloproteinase inducer), also called CD147, basigin or M6 in the human, is a member of the immunoglobulin superfamily that is present on the surface of tumor cells and stimulates adjacent fibroblasts to produce matrix metalloproteinases (MMPs). In our study, we investigated expression of EMMPRIN in human normal brain and gliomas, since mouse basigin and chicken HT7, the species homologues of human EMMPRIN, are associated with neuronal interactions and normal blood-brain barrier function, respectively. EMMPRIN expression was detected in all samples of non-neoplastic brain and glioma tissues examined. However, expression levels of EMMPRIN mRNA and protein were significantly higher in gliomas than in non-neoplastic brain. Moreover, levels of mRNA expression and immunohistochemical staining correlated with tumor progression in gliomas: They were highest in the most malignant form of glioma, glioblastoma multiforme, followed by anaplastic astrocytoma and then low-grade astrocytoma. Also, immunolocalization revealed quite different distributions in non-neoplastic brain and glioma: EMMPRIN was demonstrated only in vascular endothelium in non-neoplastic regions of the brain, whereas it was present in tumor cells but not in proliferating blood vessels in malignant gliomas. These data indicate that an MMP inducer molecule EMMPRIN is differently expressed in human normal brain and gliomas and could be associated with astrocytoma progression. Possible mechanisms whereby glioma cell EMMPRIN could influence tumor progression will be discussed.

Antigens, CD↗

PubMed2000

Glioma cell extracellular matrix metalloproteinase inducer (EMMPRIN) (CD147) stimulates production of membrane-type matrix metalloproteinases and activated gelatinase A in co-cultures with brain-derived fibroblasts.

Extracellular matrix metalloproteinase inducer (EMMPRIN) also called CD147, basigin or M6 in the human is a member of the immunoglobulin superfamily that is enriched on the surface of tumor cells and stimulates adjacent stromal cells to produce several matrix metalloproteinases (MMPs). In this study, we have demonstrated that coculturing of EMMPRIN-expressing human glioblastoma multiforme cells (U251) with brain-derived human fibroblasts not only stimulates production, but also activation of pro-gelatinase A (proMMP-2), an enzyme that is enriched in malignant gliomas and most likely crucial to tumor progression. Production of membrane types 1 and 2-MMPs (MT1-MMP and MT2-MMP), which are activators of proMMP-2, was also stimulated in these cocultures. Stimulation of MMP-2, MT1-MMP and MT2-MMP production was inhibited by anti-EMMPRIN monoclonal antibody in a dose-dependent manner. Thus, we have shown, for the first time, that EMMPRIN causes increased expression of MT1-MMP and MT2-MMP, as well as increased production and activation of MMP-2.

Antibodies, Monoclonal↗

PubMed2000

Effects of neonatal injury of the inferior alveolar nerve on the development and regeneration of periodontal nerve fibers in the rat incisor.

Our previous study showed that the migration of terminal Schwann cells occurred in the periodontal ligament of the rat lower incisor following transection of the inferior alveolar nerve (IAN) in the adult animals [Y. Atsumi, K. Matsumoto, M. Sakuda, T. Maeda, K. Kurisu, S. Wakisaka, Altered distribution of Schwann cells in the periodontal ligament of the rat incisor following resection of the inferior alveolar nerve: An immunohistochemical study on S-100 proteins, Brain Res. 849 (1999) 187-195]. The aim of the present study was to investigate the effects of neonatal transection of the IAN on the regeneration of axon elements and Schwann cells in the periodontal ligament of the rat lower incisor. Following transection of IAN at post-natal day 5 (PN 5d), when the numbers of both axon elements and the terminal Schwann cells were very small, regenerating nerve fibers appeared between post-injured days 7 (PO 7d) and PO 14d, and increased in number thereafter gradually. Although the terminal morphologies of regenerated Ruffini endings became identical to those of the adult animals by PO 54d, the number of regenerated PGP 9.5-IR nerve fibers did not recover the adult levels even by PO 56d. A small number of Schwann cells migrated into the shear zone, the border between the alveolus-related part (ARP) and the tooth-related part (TRP), but did not enter into the TRP. Following transection of the IAN at PN 14d or PN 28d, when clusters of apparent terminal Schwann cells could be recognized, axon regeneration started around PO 5d. Individual axon terminals of the regenerating Ruffini endings ramified and became identical to those of the adult animals around PO 28d, but the number of regenerated Ruffini endings was smaller than that of the adult animals. Similar to the adult animals, the migration of Schwann cells into the shear zone and TRP occurred, and disappeared prior to the completion of the axonal regeneration. The present results indicate that the migration of the Schwann cells into TRP during the regeneration of the periodontal nerve fibers following nerve injury to the IAN depends on the maturation of the terminal Schwann cells of the periodontal Ruffini endings, not on post-operative time.

Age Factors↗

PubMed2000

Calbindin D28k-like immunoreactivity during the formation of the enamel-free area in the rat molar teeth.

Previous studies have demonstrated the presence of calbindin D28k in the ameloblasts derived from the inner enamel epithelium. The occlusal surfaces of the rodent molars partly lack the enamel covering, which is referred to as enamel-free area (EFA). In the present study, we compared the immunohistochemical localization of calbindin D28k-like immunoreactivity (CB-LI) in the cells at the EFA (EFA cells) and ameloblasts of the rat molar teeth at the light microscopic level. CB-LI was strong in the ameloblasts of the presecretory through the protective stages, while it was faint at the late secretory to transitional stages. However, some mature ameloblasts lacked the immunoreactivity. On the other hand, the majority of EFA cells showed distinct polarization and elongation that were absent in few cells at the early stage of EFA formation. At all stages, the EFA cells adjacent to the ameloblasts showed CB-LI, however, some cells adjacent to the mature ameloblasts lacked the reaction. Intensive CB-LI was demonstrated in EFA cells at the reduced enamel epithelium. These immunohistochemical findings suggest EFA cells have cytochemical properties similar to those of ameloblasts.

Ameloblasts↗

PubMed2000

The development of terminal Schwann cells associated with periodontal Ruffini endings in the rat incisor ligament.

The postnatal development of the terminal Schwann cell, an analogue of the lamellar cell in cutaneous sensory receptors, was examined by histochemistry for non-specific cholinesterase and immunohistochemistry for S-100 protein in the periodontal Ruffini endings of the rat incisor. Double immunohistochemistry for S-100 protein and protein gene product 9.5 (PGP 9.5) was also performed to examine the relationship between terminal Schwann cells and axons. Histochemistry for non-specific cholinesterase was able to demonstrate the age-related development of the terminal Schwann cells; the morphology and distribution of the developing terminal Schwann cells became almost identical to those in adults during postnatal days 15-18. Axons showing PGP 9.5-like immunoreactivity elongated and expanded after arrangement of terminal Schwann cells in the alveolus-related part. This suggests that the terminal Schwann cell is important in the development and maturation of the periodontal Ruffini endings.

Animals↗