Details of a Researcher - Nakamura, Masaya

Papers - Nakamura, Masaya

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Differences in neurotrophic factor gene expression profiles between neonate and adult rat spinal cord after injury

Nakamura Masaya, Bregaman Barbara

Experimental Neurology 169 ( 2 ) 407-415 2001.06

Research paper (scientific journal), Joint Work

高齢者軸椎骨折の治療経験

Matsumoto Morio，Chiba Kazuhiro，Nishizawa Takashi，Nakamura Masaya，Maruiwa Hirofumi，Toyama Yoshiaki

日本パラプレジア医学会雑誌 14 ( 1 ) 116-117 2001.05

Research paper (scientific journal), Joint Work

Differences in neurotrophic factor gene expression profiles between neonate and adult rat spinal cord after injury

Nakamura Masaya, Bregman Barbara S.

Experimental Neurology 169 ( 2 ) 407 - 415 2001

ISSN 0014-4886

The capacity of the central nervous system for axonal growth decreases as the age of the animal at the time of injury increases. Changes in the expression of neurotrophic factors within embryonic and early postnatal spinal cord suggest that a lack of trophic support contributes to this restrictive growth environment. We examined neurotrophic factor gene profiles by ribonuclease protection assay in normal neonate and normal adult spinal cord and in neonate and adult spinal cord after injury. Our results show that in the normal developing spinal cord between postnatal days 3 (P3) and P10, compared to the normal adult spinal cord, there are higher levels of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and glial-derived neurotrophic factor (GDNF) mRNA expression and a lower level of ciliary neurotrophic factor (CNTF) mRNA expression. Between P10 and P17, there is a significant decrease in the expression of NGF, BDNF, NT-3, and GDNF mRNA and a contrasting steady and significant increase in the level of CNTF mRNA expression. These findings show that there is a critical shift in neurotrophic factor expression in normal developing spinal cord between P10 and P17. In neonate spinal cord after injury, there is a significantly higher level of BDNF mRNA expression and a significantly lower level of CNTF mRNA expression compared to those observed in the adult spinal cord after injury. These findings suggest that high levels of BDNF mRNA expression and low levels of CNTF mRNA expression play important roles in axonal regrowth in early postnatal spinal cord after injury. © 2001 Academic Press.

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Experimental study on MRI evaluation of the course of cervical spinal cord injury

Ohta Keiichi, Fujimura Yoshikazu, Nakamura Masaya, Watanabe Masahiko, Yato Yoshiyuki

Spinal Cord 37 ( 8 ) 580-584 1999.08

Research paper (scientific journal), Joint Work

Experimental study on MRI evaluation of the course of cervical spinal cord injury

Ohta K., Fujimura Y., Nakamura M., Watanabe M., Yato Y.

Spinal Cord 37 ( 8 ) 580 - 584 1999

ISSN 1362-4393

Study Design: An experimental study was conducted to evaluate MRI signal changes within the spinal cord after the injury in rats. Objectives: To clarify the significance of MRI signal changes in the injured cervical cord. Setting: Tokyo, Japan. Methods: Cervical spinal cord injury was produced in rats by placing a 20-g, or 35-g weight on exposed dura at the C6 level for 5 min (20 g- or 35 g-compression group). Motor function was evaluated by the inclined-plane method at 2, 7 and 28 days after the injury. T1- and T2-weighted images were produced by the spin-echo method with a static magnetic field strength of 2.0 tesla, at 2 and 28 days after the injury, and then the histopathological examinations were performed. Results: In the 20-g compression group which recovered from the paralysis at 28 days. MR images were T1 iso signal/T2 high signal 2 days after the injury and T1 iso signal/T2 high signal after 28 days. The changes in MRI signal 2 and 28 days represented edema and gliosis, respectively. In the 35-g compression group, which incompletely recovered from paralysis at 28 days. MR images were T1 iso-signal/T2 low signal surrounded by high signal 2 days after the injury and T1 low/T2 high signal at 28 days. The MRI signal changes 2 and 28 days reflected hemorrhage with edema and cavities, respectively. Conclusion: T2 low signal of the spinal cord observed early after injury reflects hemorrhage and may serve as an indicator of a poor prognosis. T1 low/T2 high signals from the subacute to chronic period indicated persistence of paralysis and limited recovery of function.

Multiple regression analysis of the factors influencing the results of expansive open-door laminoplasty for cervical myelopathy due to ossification of the posterior longitudinal ligament

Fujimura Y., Nishi Y., Chiba K., Nakamura M., Hirabayashi K.

Archives of Orthopaedic and Trauma Surgery 117 ( 8 ) 471 - 474 1998.10

ISSN 0936-8051

We conducted a multiple regression analysis on the surgical results (minimum follow-up of 5 years) of 55 patients who underwent expansive open-door laminoplasty (open-door ELAP) for cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL) in order to determine statistically the impact of factors influencing the results. Duration of myelopathy was found to be a significant factor indicating poor results, while progression of ossification and age at the time of surgery were significant factors indicating deterioration. Three other factors (preoperative severity of myelopathy, degree of spinal canal expansion and changes of the curve indices before and after surgery did not have a significant influence on the results. To improve the surgical results, it is thus essential to operate on patients as soon as they develop symptoms of myelopathy. There exists a certain limitation in posterior decompression for OPLL including open-door ELAP until prevention of the progression of ossification becomes possible.

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Multiple regression analysis of the factors influencing the result of expansive open-door laminoplasty for cervical myelopathy due to the ossification of the posterior longitudinal ligament

Fujimura Yoshikazu, Nishi Yukimi, Chiba Kazuhiro, Nakamura Masaya, Hirabayashi Kiyoshi

Archives of Orthopaedic and Trauma Surgery 117 ( 8 ) 471-474 1998.10

Research paper (scientific journal), Joint Work

MRI for cervical intervertebral discs in asymptomatic subjects

Matsumoto M, Fujimura Y, Suzuki N, Nishi Y, Nakamura M, Yabe Y, Shiga H

J Bone and Joint Surg 19-24 1998.08

Research paper (scientific journal), Joint Work

Changes of amino acid levels and aspartate distribution in the cervical spinal cord after traumatic spinal cord injury

Watanabe Masahiko, Fujimura Yoshikazu, Nakamura Masaya, Yato Yoshiyuki, Ohta Keiichi, Okai Hiroki, Ogawa Yuto

Journal of Neurotrauma 15 ( 4 ) 285-293 1998.04

Research paper (scientific journal), Joint Work

Influence of minor trauma on surgical results in patients with cervical OPLL

Fujimura Yoshikazu, Nakamura Masaya, Toyama Yoshiaki

J Spinal Disord 11 ( 1 ) 16-20 1998.02

Research paper (scientific journal), Joint Work

Magnetic resonance imaging of the spinal cord in cervical ossification of the posterior longitudinal ligament

Nakamura Masaya, Fujimura Yoshikazu

Spine 23 ( 1 ) 38 - 40 1998.01

ISSN 0362-2436

Study Design. Magnetic resonance imaging findings of an increased signal in the cervical cord in patients undergoing surgery for ossification of the posterior longitudinal ligament were analyzed to determined whether an increased signal on T2-weighted images correlated with a poorer outcome. Objectives. To clarify whether preoperative magnetic resonance imaging findings of a high signal in the cord constitute a poor prognostic factor. Summary of Background Data. The importance of a high, T2-weighted, intramedullary signal on preoperative magnetic resonance studies in patients undergoing surgery for ossification of the posterior longitudinal ligament requires further clarification. Methods. Of 91 patients having cervical surgery for ossification of the posterior longitudinal ligament, 26 had a history of minor trauma. High, T2-weighted signals in the cord were note din 23 patients who had sustained trauma and in 39 patients who had no history of trauma. Patients were divided into four groups according to the presence or absence of a high cord signal and/or a trauma history. Pre- and postoperative Japanese Orthopaedic Association scores and recovery ratios then were evaluated. Results. The pre-and postoperative Japanese Orthopaedic Association scores and recovery ratios of the patients with a high signal and a trauma history were significantly less than those with no high signal but with a trauma history. Among the patients with no history of trauma, however, there were no significant differences in the pre- and postoperative JOA scores and recovery ratios between the patients with a high signal and those with no high signal. Conclusion. A high preoperative cord signal on T2- weighted magnetic resonance images for patients undergoing surgery for ossification of the posterior longitudinal ligament constitutes a poor prognostic factor, when trauma has placed a role.

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MRI of cervical intervertebral discs in asymptomatic subjects

Matsumoto Morio, Fujimura Yoshikazu, Suzuki Nobumasa, Nishi Yukimi, Nakamura Masaya, Yabe Yutaka, Shiga Hayao

Journal of Bone and Joint Surgery - Series B 80 ( 1 ) 19 - 24 1998.01

ISSN 0301-620X

We studied degenerative changes in the cervical intervertebral discs of 497 asymptomatic subjects by MRI and evaluated disc degeneration by loss of signal intensity, posterior and anterior disc protrusion, narrowing of the disc space and foraminal stenosis. In each subject, five disc levels from C2-C3 to C6-C7 were evaluated. The frequency of all degenerative findings increased linearly with age. Disc degeneration was the most common observation, being present in 17% of discs of men and 12% of those of women in their twenties, and 86% and 89% of discs of both men and women over 60 years of age. We found significant differences in frequency between genders for posterior disc protrusion and foraminal stenosis. The former, with demonstrable compression of the spinal cord, was observed in 7.6% of subjects, mostly over 50 years of age. Our results should be taken into account when interpreting the MRI findings in patients with symptomatic disorders of the cervical spine.

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Magnetic resonance imaging of the spinal cord in cervical ossification of the posterior longitudinal ligament; can it predict surgical outcome?

Nakamura M, Fujimura Yoshikazu

Spine 23 ( 1 ) 38-40 1998.01

Research paper (scientific journal), Joint Work

MRI of cervical intervertebral discs in asymptomatic subjects

Matsumoto Morio, Fujimura Yoshikazu, Suzuki Nobuyuki, Nishi Yukimi, Nakamura Masaya, Yabe Yutaka, Shiga Hayao

J Bone Joint Surg 80-B ( 1 ) 19-24 1998.01

Research paper (scientific journal), Joint Work

Influence of minor trauma on surgical results in patients with cervical OPLL

Fujimura Yoshikazu, Nakamura Masaya, Toyama Yoshiaki

Journal of Spinal Disorders 11 ( 1 ) 16 - 20 1998

ISSN 0895-0385

This study was designed to evaluate the relationship between minor trauma and surgical results of cervical ossification of the posterior longitudinal ligament (OPLL), focusing on static compressive and dynamic factors contributing to cord compression plus the type of attendant OPLL. Of the 91 patients treated surgically, 26 had sustained minor trauma (injury group), and the other 65 had no trauma (noninjury group). The pre- /postoperative JOA scores and recovery ratio for the injury group were significantly lower than those for the noninjury group. In the segmental, localized, and mixed types, which had good ranges of motion of the cervical spine, the recovery ratios of the injury group were significantly lower than those of the noninjury group. In the continuous type, which had a poor range of motion and severe spinal cord compression, there was no significant difference in the recovery ratio between the injury and noninjury groups. Thus, dynamic factors may play an important role in neurologic deterioration after minor trauma in patients with segmental, mixed, and localized cervical OPLL.

Anterior Decompression and Fusion via the Extrapleural Approach for Thoracic Disc Herniation Causing Myelopathy

Fujimura Yoshikazu, Nakamura Masaya, Matsumoto Mono

Keio Journal of Medicine 46 ( 4 ) 173 - 176 1997.12

ISSN 0022-9717

Anterior decompression and fusion via an extrapleural approach was performed for 33 patients with myelopathy arising from thoracic disc herniation and the clinical usefulness and problems related to this procedure were assessed on the basis of surgical results and complications. The severity of the myelopathy was evaluated by the Japanese Orthopaedic Association score, and the surgical results were based on the recovery rate. The upper-level limit of decompression and fusion via the extrapleural approach was T4-5. The recovery rate for the mean postoperative follow-up period of 41 months was 66.7%. An age of 60 years or more, long duration of illness and severe preoperative myelopathy were indicators of a poor prognosis. Two patients suffered from a postoperative transient pulmonary complication due to hemothorax. X-ray examinations revealed good bone union in all the patients. The present study indicates that anterior decompression and fusion via the extrapleural approach is a useful technique which can be used to achieve a high success rate in the surgical treatment of thoracic disc herniation, if intervention is early.

Anterior decompression and fusion via extrapleural approach for thoracic disc herniation causing myelopathy

Fujimura Yoshikazu, Nakamura Masaya, Matsumoto Morio

Keio J Med 46 ( 4 ) 173-176 1997.12

Research paper (scientific journal), Joint Work

Decreased choline acetyltransferase activity in the murine spinal cord motoneurons under chronic mechanical compression

Yato Yoshiyuki, Fujimura Yoshikazu, Nakamura Masaya, Watanabe Masahiko, Yabe Yutaka

Spinal Cord 35 ( 11 ) 729-734 1997.11

Research paper (scientific journal), Joint Work

Myelopathy secondary to ossification of the posterior longitudinal ligament of the thoracic spine treated by anterior decompression and bony fusion

Fujimura Yoshikazu, Nishi Yukimi, Nakamura Masaya, Watanabe Masahiko, Matsumoto Morio

Spinal Cord 35 ( 11 ) 777-784 1997.11

Research paper (scientific journal), Joint Work

Muscle reorganization following incomplete spinal cord injury the rats

Nakamura Masaya, Fujimura Yoshikazu, Ogawa Yuto, Okai Hiroki,Ohta Keiichi, Yato Yoshiyuki, Watanabe Masahiko

Spinal Cord 35 ( 11 ) 752-756 1997.11

Research paper (scientific journal), Joint Work

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