Y Maezawa

Fukui University, Hukui, Fukui, Japan

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Publications (40)91.57 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: The purpose of the present study was to identify any compensatory changes at the site of chronic compression of the spinal cord and neighboring segments. For this purpose, serial immunohistochemical and immunoblot analyses were performed for the expression levels of endogenous brain-derived neurotrophic factor (BDNF), neurotrophin (NT)-3, and their receptors, trkB and trkC in 24 tip-toe walking Yoshimura mice (twy/twy) aged 12-24 weeks. The twy mouse exhibits spontaneous calcified deposits posteriorly at the C1-C2 level, compressing the spinal cord. Immunoreactivities for BDNF, NT-3, trkB and trkC were preferentially localized in the gray matter, particularly in the anterior horn cells. In 24-week-old twy mice with severe compression, expression levels of these neurotrophins at the site of maximal compression were significantly lower than at the less- or non-compressed sites. In contrast, the expression levels of BDNF, NT-3, trkB and trkC were significantly higher at the rostral and caudal sites immediately adjacent to the maximal compression site. No such changes were noted in 12-week-old twy mice or in control Institute of Cancer Research mice. Our results suggest that overexpression of BDNF, NT-3, trkB and trkC in motoneuron areas neighboring the site of mechanical compression may represent compensatory changes in response to the compromised neuronal function at the level of compression, and that these proteins possibly contribute to neuronal survival and plasticity.
    Acta Neuropathologica 08/2003; 106(1):29-36. · 9.73 Impact Factor
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    ABSTRACT: Immunohistochemical examination of the expression and localization of neurofilament (NF) proteins and growth-associated protein (GAP)-43 in spinal hyperostotic (twy/twy) mice with progressive compression of the cervical spinal cord. To determine the biologic functions of NF proteins and GAP-43 in the mouse cervical spinal cord during chronic mechanical compression. The pathologic and repair process in the chronically compressed spinal cord are understood poorly. The present authors hypothesized that there existed an increased expression of NF proteins and GAP-43 in twy/twy mice during the lengthy period of spinal cord compression, which resembles compressive myelopathy. The cervical spinal cords of 54 twy mice (aged 8 weeks [n = 18], 14 weeks [n = 18], and 20 weeks [n = 18]) and 18 control animals were examined histologically. Using appropriate antibodies, sections were also stained immunohistochemically for NF proteins and GAP-43. Separation of the myelin sheath from the axon and axonal swelling with deformation were detected in the anterior and lateral funiculi of the spinalcords of 20-week-old twy/twy mice. No such changes were noted in 8-week-old twy mice. In twy/twy mice aged 8 and 14 weeks with mild-to-moderate compression, weak immunoreactivities (mainly in the white matter) for NF proteins and GAP-43 were noted; however, in 20-week-old twy/twy mice, these axons stained strongly positive and immunoreactive swollen axons were present. The relative area of GAP-43 immunoreactive axons gradually increased between 8 and 20 weeks in each column, particularly in the anterior and lateral funiculi in the contralateral side of compression. The results showed that the expression of NF proteins and GAP-43 in the white matter increased proportionally with the magnitude of spinal cord compression, and indicated the possible involvement of GAP-43 in both axonal degeneration and repair processes in the chronically compressed spinal cord.
    Spine 04/2002; 27(5):480-6. · 2.16 Impact Factor
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    ABSTRACT: Surgically obtained cervical herniated intervertebral discs were examined histologically and immunohistochemically. The production of nitric oxide (NO) in the local tissue was examined using the electron spin resonance (ESR) method. To investigate the local histologic and immunohistochemical changes in cervical disc herniation, including NO production, and to compare such changes with those in autopsy cases. Very little is known about the histopathologic processes of cervical disc herniation. In addition, no information is available on the level of in vivo NO production in cervical disc herniation. Thirty-six herniated cervical discs obtained from 31 patients were immunohistochemically examined for localization of blood vessels, matrix metalloproteinase (MMP)-3, and inducible NO synthetase (iNOS). We also compared the production of NO, measured by the ESR method, in eight specimens with that of five control discs obtained from fresh cadavers. The presence of herniated discs correlated with the degeneration of cartilaginous endplate and torn anulus fibrosus. Formation of new blood vessels around the herniated discs was detected, using von Willebrand factor antibody, in seven uncontained hernias and 20 contained hernias. Immunohistochemical studies showed the presence of cells positive for MMP-3 (chondrocytes), iNOS (chondrocytes and granulation tissue) in cervical disc hernias. ESR analysis showed a significantly higher NO production in herniated cervical discs than in disc samples of fresh cadavers. Herniated cervical intervertebral disc is characterized by the presence of an inflammatory process associated with neovascularization and increased expression of MMP-3. Production of NO was markedly high in both contained- and uncontained-type hernias.
    Spine 06/2001; 26(10):1110-6. · 2.16 Impact Factor
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    ABSTRACT: To investigate the relationships among bone mineral density (BMD), static alignment and the adduction moment of the knee in patients with tibiofemoral osteoarthritis (OA). Sixty-nine patients with medial compartment knee OA underwent radiographic evaluation, gait analysis and BMD measurements at the proximal tibia and lumbar spine. The bone mineral distribution of the medial to lateral part of the proximal tibia correlated significantly with the peak knee adduction moment and the mechanical axis. Furthermore, the adduction moment correlated significantly with the mechanical axis. However, the BMD of the lumbar spine and the bone mineral distribution of the posterior to anterior part of the proximal tibia did not correlate with any other measurement. Our results suggest that the bone mineral distribution of the proximal tibia is directly affected but lumbar BMD is not influenced by the local mechanical stress around the knee with medial compartment OA.
    Rheumatology 06/2001; 40(5):499-505. · 4.21 Impact Factor
  • Y Maezawa, K Uchida, H Baba
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    ABSTRACT: To assess neurological status and to evaluate the effect of surgical decompression in patients with cervical myelopathy, we performed computerized gait analysis in 24 patients with cervical compressive myelopathy who showed spastic walking. Gait analysis was repeated during neurological follow-up that averaged 32.4 months. The gait pattern in patients with severe myelopathy was characterized by hyperextension of the knee in the stance phase without plantar flexion of the ankle in the swing phase, significantly reduced walking speed and step length, prolonged stance phase duration and decreased single-stance phase duration, and increased step width. The angle of flexion of the knee joint in the stance phase was significantly correlated with the Japanese Orthopaedic Association (JOA) score. Postoperative neurological improvement was associated with increased walking speed and decreased extension angle of the knee joint (single-stance phase and swing phase). Postoperatively, 12 patients had normalized extension of the knee in stance phase and their walking speed, cadence, stance phase duration, and single-stance phase duration, as well as step length and width, showed nonsignificant differences from these parameters in healthy controls. Our results show that kinesiological gait analysis is clinically useful for the functional assessment of the severity of spastic walking in cervical myelopathy.
    Journal of Orthopaedic Science 02/2001; 6(5):378-84. · 0.96 Impact Factor
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    ABSTRACT: We report a case of a hematoma of ligamentum flavum at T11-12 in a 66-year-old man who presented with progressive weakness of the right foot and numbness of both legs. Past history was negative and no precipitating episode of lower back sprain or trauma. The resected T11 and T12 laminas showed old hematoma with degenerative changes in the ligamentum flavum. Hematoma occurring in the thoracic spine has never been reported previously.
    Clinical Imaging 01/2001; 25(4):265-7. · 0.65 Impact Factor
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    ABSTRACT: We report on a 15-year-old boy in whom a spontaneous remission of a symptomatic synovial cyst, possibly emanating from the L4-5 facet joint, was noted. The medical history suggested that sport-related overactivity and/or minor trauma was the underlying cause. Conservative treatment for several months may be one treatment option if the cyst wall is not calcified and the symptoms and signs related to radiculopathy show a gradual decrease.
    European Spine Journal 03/2000; 9(1):85-7. · 2.13 Impact Factor
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    ABSTRACT: We examined immunohistochemically the fracture repair process in rat tibial bone using antibodies to PCNA, BMP2, TGF-beta 1,-2,-3, TGF-beta R1,-R2, bFGF, bFGFR, PDGF, VEGF, and S-100. The peak level of cell proliferation as revealed by PCNA labelling appeared first in primitive mesenchymal cells and inflammatory cells at the fracture edges and neighboring periosteum at 2-days after fracture, followed by the peaks of periosteal primitive fibroblasts and chondroblasts, which appeared at fracture edges at 3- and 4-days after fracture, respectively. BMP2 was weakly positive in primitive mesenchymal cells, osteoblasts and chondroblasts. At 3-days post-fracture, periosteal osteoblasts produced osteoid tissue and callus with marrow spaces lined by osteoblasts and osteoclasts, and all primitive mesenchymal cells and osteoblasts were positive for TGF-beta 1,-2,-3, and TGF-beta R1,-R2. They were also positive for vascular growth factors bFGF, FGFR and PDGF, but negative for VEGF, and the peak of PCNA labelling of vascular endothelial cells in the marrow space was delayed to 4-days after fracture. Chondroblasts at fracture edges produced hypertrophic chondrocytes at 5-days after fracture and they were positive for TGF-beta 1,-2,-3, and TGF-beta R1,-R2. Primitive chondroblasts were positive for vascular growth factors VEGF as well as bFGF, FGFR, and the peak of PCNA labelling of vascular endothelial cells in the cartilage was at 5-days after fracture. Hypertrophic chondrocytes were also positive for these growth factors but negative for bFGF and bFGFR. S-100 protein-induced calcification was only positive on chondroblasts and hypertrophic chondrocytes. At 7-days after fracture, bone began to be formed from the cartilage at fracture edges, by a process similar to bone formation in the growth plate. Enchondral ossification established a bridge between both fracture edges and periosteal membranous ossification encompassed the fracture site like a sheath at 14 day after fracture. Our study of fracture repair of bone indicates that this process is complex and occurs through various steps involving various growth factors.
    European journal of histochemistry: EJH 02/2000; 44(3):269-78. · 2.41 Impact Factor
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    ABSTRACT: This case study describes the usefulness of high-resolution 18F-2-fluoro-deoxy-D-glucose (18FDG)-positron emission tomography (PET) for metabolic neuroimaging of the cervical spinal cord in patients with compressive myelopathy. To examine whether 18FDG-PET imaging could visualize deterioration of cervical spinal cord function associated with a variable degree of compression and to determine its potential usefulness during assessment of myelopathy. A few studies have described the use of 18FDG-PET imaging in cervical cord diseases, but visualization of the cervical spinal cord before and after surgical decompression for compressive myelopathy has not been reported. The potential usefulness of 18FDG-PET imaging for assessment of the function of compressed cervical cord has not been discussed previously. An 18FDG-PET scan was performed before and after surgery in seven patients with cervical compressive myelopathy. The correlation between the metabolic rate of glucose of the cervical spinal cord and neurologic scores was evaluated. The metabolic rate of glucose in different vertebral levels was also measured. Preoperative metabolic rate of glucose was high in two patients but low in the other five. At the time of the second postoperative examination, metabolic rate of glucose was higher in six of the seven patients, and the increase was associated with neurologic improvement. Use of 18FDG was not related to changes in signal intensities on T2-weighted magnetic resonance images. The metabolic rate of glucose decreased at the affected vertebral level in four patients, increased in two, and did not change in one, relative to the unaffected levels. High-resolution 18FDG-PET neuroimaging may provide clinically useful qualitative and quantitative estimation of impaired metabolic activity of the compromised cervical spinal cord in compressive myelopathy. 18FDG-PET images may also offer additional information related to neuronal dysfunction induced by mechanical compression.
    Spine 08/1999; 24(14):1449-54. · 2.16 Impact Factor
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    ABSTRACT: We examined the morphology of spinal accessory motoneurons and immunoreactivity to neurotrophins, brain-derived neurotropic factor (BDNF) and neurotrophin (NT)-3, as well as the presence of reactive astrocytosis in 70 tiptoe walking Yoshimura (twy) mice that develop calcification at C1-C2 vertebral level compressing the spinal cord. At the level of compression, the area of neuronal soma and total length of dendrites of wheat germ agglutinin-horseradish peroxidase (WGA-HRP)-labelled accessory motoneurons in the medial cell pool decreased significantly with decrement in motoneuron population, relative to the control. In contrast, at sites rostral to the compressive lesion, a significant enlargement of the neuron soma and dendritic elongation were noted, associated with increased motoneuron population and decreased transverse area of the cord at the level of compression. At this site, enhanced BDNF and NT-3 immunoreactivities were evident in the anterior horn cells. In mice with a more severe degree of compression, astrocyte-like cells showing BDNF immunoreactivity became abundant and axons in the anterior column demonstrated a marked NT-3 immunoreactivity. Our results suggest increased functional activity of anterior horn cells at levels rostra] to the site of compression. We speculate that the presence of BDNF and NT-3 in neurons and astrocyte-like cells is proportionate to the severity of chronic mechanical compression and may contribute to the heterotropic neuronal reserve and survival.
    Journal of Neurology 01/1999; 245(12):781-93. · 3.58 Impact Factor
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    ABSTRACT: We report eight patients with a solitary plasmacytoma of the spine associated with neurological complications. The patients included five men and three women with an average age at presentation of 59 years (range, 47 to 73 years). The tumour was confined to the thoracic spine in six cases, cervical spine in one and lumbar spine in one. Duration of symptoms ranged from 2.5 to 22 months. Treatment consisted of a combination of radiotherapy, melphalan and surgery. One patient progressed to multiple myeloma 7 years after surgery. Surgical treatment (anterior surgery in three cases and posterior surgery in five) produced neurological improvement in all patients. We stress the importance of an early diagnosis followed by appropriate treatment including surgery for this clinical entity and long-term follow-up to detect a disseminated disease.
    Spinal Cord 08/1998; 36(7):470-5. · 1.90 Impact Factor
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    ABSTRACT: In an attempt to formulate a standardised approach to the diagnosis and management of patients with the double-crush syndrome, we reviewed 65 surgical cases (39 men and 26 women) with cervical myeloradiculopathy associated with entrapment neuropathy in the arm by examining the clinical features, results of nerve conduction velocity studies and distribution of the vertebral levels of compression. Fifty-three patients (average age, 43 years) presented with a carpal tunnel syndrome at the wrist and cervical lesions (41 with spondylosis and 12 with ossified posterior longitudinal ligament), while 12 had a cubital tunnel syndrome at the elbow with cervical lesions (eight with spondylosis and four with ossification of the posterior longitudinal ligament). In the former group, the lesions were found mostly at C5-6 and C6-7 levels, while in the latter group involvement of C6-7 was frequently observed. Two patients in each group required additional cervical decompression after carpal or cubital tunnel release. A retrospective review of our patients suggested that it is reasonable to pursue an accurate diagnosis followed by treatment based on individual neurological and electrophysiological findings, but taking into consideration the significant level of physical impairment associated with cord compromise, we believe that it may be reasonable to perform a cervical decompression rather than peripheral nerve release in such cases. Our findings suggest that one should be aware of a double-crush during examination of patients complaining of neck and hand problems.
    Spinal Cord 07/1998; 36(6):399-404. · 1.90 Impact Factor
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    ABSTRACT: We describe two unusual surgical cases who presented with extraforaminal lumbar disc herniation that occurred at two adjacent vertebral levels simultaneously and unilaterally. Magnetic resonance imaging and selective nerve root infiltration followed by radiculography helped to outline the herniated disc material. Lateral fenestration and microsurgical foraminal widening of the affected vertebral levels allowed a complete and safe relief of the compressed nerves.
    Spinal Cord 12/1997; 35(11):725-8. · 1.90 Impact Factor
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    ABSTRACT: We evaluated the use of three-dimensional (spiral) computed tomography (CT) to assess widening of the bony cervical spinal canal following en bloc open-door C3-C7 laminoplasty in 31 patients. Measurements were performed using a computerised image processing system. The increment in the anteroposterior spinal canal axis and volume of the bony spinal canal was investigated in relation to changes in cervical spine lordosis as well as postoperative neurological improvement. Neurological follow-up averaged 2.6 years (range, 1 to 7 years). A mean increase of 42% was observed in the anteroposterior axis of the canal between C3 to C7 after surgery, while the volume increased by 45%. Postoperatively, cervical spine lordosis correlated with increments in the volume of the enlarged bony canal rather than the anteroposterior axis. Postoperative neurological improvement correlated significantly with the increase in the canal volume. Our results indicate that spiral CT is useful for the assessment of the magnitude of cervical canal enlargement and evaluating the space available for the spinal cord following the relief of compression.
    Spinal Cord 11/1997; 35(10):674-9. · 1.90 Impact Factor
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    ABSTRACT: We describe a man aged 26 years who presented with a neurological syndrome, which was found on lumbar radioculopathy to be due to a ganglion cyst originating from the posterior longitudinal ligament. Based on MRI findings, cystic lesion was suspected, a round lesion at L4 level with no connection to the adjacent facet or to the dura matter. During surgery, a liquid-containing cystic lesion was found to originate from the posterior longitudinal ligament at L4 level. The resected cyst was diagnosed histologically as a ganglion cyst. A complete cure was established after surgery and no recurrence was noted at a follow-up 1.7 years postoperatively. A ganglion cyst of the posterior longitudinal ligament should be considered in the differential diagnosis of a cyst in the lumbar region causing neurological complications.
    Spinal Cord 10/1997; 35(9):632-5. · 1.90 Impact Factor
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    ABSTRACT: To investigate the relationship between morphological plasticity of the spinal cord and neurological outcome after surgery for compressive lesions, we correlated the transverse area of the cervical spinal cord measured by transaxial magnetic resonance imaging (MRI) obtained during the early postoperative period (1-6 months) with neurological function assessed at a median postoperative follow-up period of 2.5 years. Measurements on MRI in 56 patients (35 men and 21 women) included evaluation of the cross-sectional area of the cervical cord and the subarachnoidal space at the level of decompression. The transverse area of the cervical cord increased by 30 to 62% postoperatively and that of the subarachnoidal space by 57 to 95%. Neurological improvement was noted in all patients and averaged 63% in our assessment scale. Expansion of the cervical cord during the early postoperative period correlated significantly with the late postoperative neurological status (P = 0.009). Our results suggest that an increase in the cross-sectional area of the cervical spinal cord, representing spinal cord morphological plasticity, is a significant factor in determining the late neurological improvement following decompressive surgery.
    Journal of Neurology 08/1997; 244(7):455-60. · 3.58 Impact Factor
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    ABSTRACT: We investigated the effect of chronic mechanical compression of the cervical spinal cord on the number of spinal accessory motoneurons in 25 tiptoe-walking Yoshimura mice. The animals had calcified deposits in the atlantoaxial membrane at the C1-C2 vertebral level, compressing the spinal cord posterolaterally. Motoneurons of the spinal accessory nerve between C1 and C5 segments were labelled using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injected into the sternocleidomastoid muscles. The counted cells were processed into a three-dimensional computer display to analyse the cytoarchitectonic changes caused by external cord compression. The number of WGA-HRP-labelled spinal accessory motoneurons was significantly reduced on the affected side. The number of motoneurons in compromised C2 and C3 cord segments correlated linearly with the extent of mechanical compression, but no such relationship was present on the contralateral side. There was an increase in the number of WGA-HRP-labelled spinal accessory motoneurons in the medial cell pools of the anterior grey horn at a level most rostral to the compression, and in the ventrolateral cell pools at levels immediately rostral to the compression. Our findings suggest that the spinal accessory motoneurons translocate rostral to the area of external compression in order to avoid mechanical injury.
    Journal of Neurology 05/1997; 244(4):222-9. · 3.58 Impact Factor
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    ABSTRACT: We examined the histological and immunohistochemical changes within and around herniated cervical intervertebral discs. A total of 28 herniated discs were harvested en bloc during anterior decompressive surgeries and examined together with the surrounding tissues. The presence of herniated discs correlated with the degeneration of cartilaginous endplate and torn annulus fibrosus. Formation of new blood vessels around the herniated discs was detected, using von Willebrand factor antibody, in seven (25% of all) uncontained hernias and eight (38%) contained hernias. Immunohistochemical studies using specific antibodies showed the presence of cells positive for matrix metalloproteinase-3 (chondrocytes), CD68 (macrophages and monocytes), and interleukin-1 beta (endothelial cells), in cervical disc hernias. Our results suggested that the magnitude and degree of immunohistochemical tissue reaction in cervical disc herniation correlate with the extent as well as location of herniated disc material.
    European journal of histochemistry: EJH 02/1997; 41(4):261-70. · 2.41 Impact Factor
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    ABSTRACT: We investigated the effects of streptozotocin-induced diabetes mellitus on ossification of the posterior longitudinal ligament (OPLL) in the murine cervical spine. A genetically-bound spinal hyperostotic mouse, the tip-toe walking Yoshimura (twy) mouse, was used in these experiments. Histological examination showed that streptozotocin enhanced membranous and enchondral ossification of the posterior longitudinal ligament of the cervical spine, particularly in the area of the ligamentous enthesis. It also increased the number of alkaline phosphatase-positive osteoblast-like mesenchymal cells particularly around the enthesis, while the number of such cells was less in control twy mice and ICR mice treated with streptozotocin. The area of OPLL subsequently increased in size in streptozotocin-treated twy mice. We suggest that streptozotocin-induced diabetes enhances OPLL in the genetically-bound spinal hyperostotic mouse (twy/twy).
    European journal of histochemistry: EJH 02/1997; 41(3):191-202. · 2.41 Impact Factor
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    ABSTRACT: We report a 69-year-old woman who developed serious hydrocephalus after cervical laminoplasty for ossification of the posterior longitudinal ligament. The patient presented with approximately 50% spinal canal compromise pertaining to ossified lesion at C5 and C6 levels and subsequently underwent a C3-C7 open-door laminoplasty, followed by uneventful neurological recovery until 2 weeks postoperatively. Despite a favourable postoperative course, she presented with serious symptoms and signs of intracranial hypertension about 3 weeks after surgery. Computed tomography demonstrated the appearance of marked hydrocephalus, with no explainable cause. A ventriculoperitoneal shunt followed by removal of subdural fluid in the suboccipital fossa resulted in resolution of the clinical symptoms and of the hydrocephalus. It is important to be aware of the very rare occurrence of such intracranial neurological compromise after a cervical laminoplasty operation for long-standing ossification of the posterior longitudinal ligament.
    Spinal Cord 12/1996; 34(11):699-702. · 1.90 Impact Factor