Biomedical subjects

Masaya Nakamura

Publications and source records attributed to Masaya Nakamura.

At least 19 recordsLinked to original sources

PubMed2007

Transformation of the mycorrhizal basidiomycetes, Suillus grevillei and S. bovinus, by particle bombardment.

Mycorrhizal basidiomycetes, Suillus grevillei and S. bovinus, were transformed by particle bombardment. We isolated eight and four transformants from S. grevillei and S. bovinus respectively under three conditions differing in terms of target distance and helium pressure. The transformation frequencies were 1.2 and 0.6 transformants/microg DNA. Plasmid DNAs were integrated into the genomic DNA of the transformants and stably maintained. This is the first description of the transformation of S. grevillei and S. bovinus by particle bombardment.

Basidiomycota↗

PubMed2006

Long-term results of expansive open-door laminoplasty for cervical myelopathy--average 14-year follow-up study.

STUDY DESIGN: Retrospective case series on long-term follow-up results of original expansive open-door laminoplasty for cervical myelopathy due to cervical spondylosis (CSM) and ossification of posterior longitudinal ligament (OPLL). OBJECTIVES: To elucidate efficacy and problems of original open-door laminoplasty to improve future surgical outcomes. SUMMARY OF BACKGROUND DATA: Little information is available on long-term outcomes of original open-door laminoplasty without grafts, implants, or instruments. METHOD: The study group included 80 patients who underwent original open-door laminoplasty and were followed for minimum 10 years. Clinical results, including Japanese Orthopedic Association scores, recovery rates, occurrences of complications, and long-term deterioration were investigated. Cervical alignments, type of OPLL, cervical range of motion, anteroposterior diameter of spinal canal, and progression of OPLL were assessed on plain radiographs. Spinal cord decompression was verified on magnetic resonance imaging. RESULTS: Average Japanese Orthopedic Association score and recovery rate improved significantly until 3 years after surgery and remained at an acceptable level in both cervical spondylosis and OPLL patients with slight deterioration after 5 years. Segmental motor palsy developed in 8 patients. Late deterioration, mainly lower extremity motor score decline, developed in 8 CSM and 16 OPLL patients. Overall cervical range of motion decreased by 36%. Patients with cervical lordosis decreased gradually in both patient groups. Such changes in alignments did not affect surgical results in CSM patients, while OPLL patients with preoperative kyphosis had lower recovery rates than those with straight and lordotic alignments. OPLL progression that was detected in 66% of patients did not affect clinical results. Although infrequent, magnetic resonance imaging revealed atrophy of spinal cord, spinal cord compression at adjacent segments due to degenerative changes and OPLL progression. CONCLUSIONS: Long-term results of open-door laminoplasty without bone graft, graft substitutes, or instruments were satisfactory. However, segmental motor paralysis, kyphosis, established before and after surgery, OPLL progression, and late deterioration due to age-related degeneration remain challenging problems.

Adult↗

PubMed2006

Electrical stimulation modulates fate determination of differentiating embryonic stem cells.

A clear understanding of cell fate regulation during differentiation is key in successfully using stem cells for therapeutic applications. Here, we report that mild electrical stimulation strongly influences embryonic stem cells to assume a neuronal fate. Although the resulting neuronal cells showed no sign of specific terminal differentiation in culture, they showed potential to differentiate into various types of neurons in vivo, and, in adult mice, contributed to the injured spinal cord as neuronal cells. Induction of calcium ion influx is significant in this differentiation system. This phenomenon opens up possibilities for understanding novel mechanisms underlying cellular differentiation and early development, and, perhaps more importantly, suggests possibilities for treatments in medical contexts.

Animals↗

PubMed2006

A selective Sema3A inhibitor enhances regenerative responses and functional recovery of the injured spinal cord.

Axons in the adult mammalian central nervous system (CNS) exhibit little regeneration after injury. It has been suggested that several axonal growth inhibitors prevent CNS axonal regeneration. Recent research has demonstrated that semaphorin3A (Sema3A) is one of the major inhibitors of axonal regeneration. We identified a strong and selective inhibitor of Sema3A, SM-216289, from the fermentation broth of a fungal strain. To examine the effect of SM-216289 in vivo, we transected the spinal cord of adult rats and administered SM-216289 into the lesion site for 4 weeks. Rats treated with SM-216289 showed substantially enhanced regeneration and/or preservation of injured axons, robust Schwann cell-mediated myelination and axonal regeneration in the lesion site, appreciable decreases in apoptotic cell number and marked enhancement of angiogenesis, resulting in considerably better functional recovery. Thus, Sema3A is essential for the inhibition of axonal regeneration and other regenerative responses after spinal cord injury (SCI). These results support the possibility of using Sema3A inhibitors in the treatment of human SCI.

Animals↗

PubMed2006

Posterior osteotomy and instrumentation for thoracolumbar kyphosis in patients with achondroplasia.

STUDY DESIGN: A retrospective case series of surgically treated achondroplastic patients with severe thoracolumbar kyphosis. OBJECTIVE: To evaluate the outcome of surgical treatment for thoracolumbar kyphosis in patients associated with achondroplasia presenting with paraparesis. SUMMARY OF BACKGROUND DATA: Thoracolumbar kyphosis is one of the frequent skeletal manifestations in patients with achondroplasia. Few papers have been published on the surgical treatment of this condition, especially in skeletally mature patients. METHODS: Four patients with achondroplasia who developed neurologic deficit due to severe thoracolumbar kyphosis and underwent surgical treatment were evaluated (mean age, 32.5 years; mean follow-up, 3.0 years). Posterior osteotomy with segmental instrumentation was performed in all cases. The surgical procedures included pedicle subtraction osteotomy in 2 patients without a hypoplastic apical vertebra and spondylectomy with reconstruction of the anterior column in 2 patients with a hypoplastic apical vertebra. Neurologic outcomes (JOA scores), correction of kyphosis, and operative complications were assessed. RESULTS: All patients had gait disturbance, and 2 patients were unambulatory before surgery. The average preoperative JOA score was 5.8 points, which was improved to 9.3 points at the final follow-up (mean recovery rate, 75%). All patients obtained neurologic improvement and became ambulatory either with or without crutches after surgery. The mean preoperative kyphotic angle was 96.3 degrees (range, 57 degrees -117 degrees ). The postoperative angles averaged 55.3 degrees (range, 30 degrees -110 degrees ), yielding a mean correction rate of 43.6%. Neither loss of correction nor pseudarthrosis has been observed during the follow-up period. Partial nerve root laceration and dural tear resulting in transient postoperative muscle weakness were observed in 2 patients as complications. CONCLUSIONS: Posterior spinal osteotomy with segmental instrumentation is a reasonable surgical option for thoracolumbar kyphosis in patients with achondroplasia. Modification of the surgical procedures depending on the presence or absence of the dysplastic changes of the apical vertebra is necessary to obtain optimal results.

Achondroplasia↗

PubMed2006

Conditional ablation of Stat3 or Socs3 discloses a dual role for reactive astrocytes after spinal cord injury.

In the injured central nervous system (CNS), reactive astrocytes form a glial scar and are considered to be detrimental for axonal regeneration, but their function remains elusive. Here we show that reactive astrocytes have a crucial role in wound healing and functional recovery by using mice with a selective deletion of the protein signal transducer and activator of transcription 3 (Stat3) or the protein suppressor of cytokine signaling 3 (Socs3) under the control of the Nes promoter-enhancer (Nes-Stat3(-/-), Nes-Socs3(-/-)). Reactive astrocytes in Nes-Stat3(-/-) mice showed limited migration and resulted in markedly widespread infiltration of inflammatory cells, neural disruption and demyelination with severe motor deficits after contusive spinal cord injury (SCI). On the contrary, we observed rapid migration of reactive astrocytes to seclude inflammatory cells, enhanced contraction of lesion area and notable improvement in functional recovery in Nes-Socs3(-/-) mice. These results suggest that Stat3 is a key regulator of reactive astrocytes in the healing process after SCI, providing a potential target for intervention in the treatment of CNS injury.

Animals↗

PubMed2006

Disease progression of human SOD1 (G93A) transgenic ALS model rats.

The recent development of a rat model of amyotrophic lateral sclerosis (ALS) in which the rats harbor a mutated human SOD1 (G93A) gene has greatly expanded the range of potential experiments, because the rats' large size permits biochemical analyses and therapeutic trials, such as the intrathecal injection of new drugs and stem cell transplantation. The precise nature of this disease model remains unclear. We described three disease phenotypes: the forelimb-, hindlimb-, and general-types. We also established a simple, non-invasive, and objective evaluation system using the body weight, inclined plane test, cage activity, automated motion analysis system (SCANET), and righting reflex. Moreover, we created a novel scale, the Motor score, which can be used with any phenotype and does not require special apparatuses. With these methods, we uniformly and quantitatively assessed the onset, progression, and disease duration, and clearly presented the variable clinical course of this model; disease progression after the onset was more aggressive in the forelimb-type than in the hindlimb-type. More importantly, the disease stages defined by our evaluation system correlated well with the loss of spinal motor neurons. In particular, the onset of muscle weakness coincided with the loss of approximately 50% of spinal motor neurons. This study should provide a valuable tool for future experiments to test potential ALS therapies.

Aging↗

PubMed2006

Neutralization of ciliary neurotrophic factor reduces astrocyte production from transplanted neural stem cells and promotes regeneration of corticospinal tract fibers in spinal cord injury.

Transplantation of neural stem cells (NSC) into lesioned spinal cord offers the potential to increase regeneration by replacing lost neurons or oligodendrocytes. The majority of transplanted NSC, however, typically differentiate into astrocytes that may exacerbate glial scar formation. Here we show that blocking of ciliary neurotrophic factor (CNTF) with anti-CNTF antibodies after NSC transplant into spinal cord injury (SCI) resulted in a reduction of glial scar formation by 8 weeks. Treated animals had a wider distribution of transplanted NSC compared with the control animals. The NSC around the lesion coexpressed either nestin or markers for neurons, oligodendrocytes, or astrocytes. Approximately 20% fewer glial fibrillary acidic protein-positive/bromodeoxyuridine (BrdU)-positive cells were seen at 2, 4, and 8 weeks postgrafting, compared with the control animals. Furthermore, more CNPase(+)/BrdU(+) cells were detected in the treated group at 4 and 8 weeks. These CNPase(+) or Rip(+) mature oligodendrocytes were seen in close proximity to host corticospinal tract (CST) and 5HT(+) serotonergic axon. We also demonstrate that the number of regenerated CST fibers both at the lesion and at caudal sites in treated animals was significantly greater than that in the control animals at 8 weeks. We suggest that the blocking of CNTF at the beginning of SCI provides a more favorable environment for the differentiation of transplanted NSC and the regeneration of host axons.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

PubMed2006

Microendoscopic partial resection of the sacral ala to relieve extraforaminal entrapment of the L-5 spinal nerve at the lumbosacral tunnel. Technical note.

The authors report the cases of three patients with L-5 radiculopathy caused by extraforaminal entrapment of the L-5 spinal nerve at the lumbosacral tunnel; this structure comprises the lumbosacral ligament, the sacral ala, and the L-5 and S-1 vertebral bodies. All three patients suffered severe leg pain and neurological deficits compatible with L-5 radiculopathy. Decompressive surgery involved the microendoscopic partial resection of the sacral ala along the L-5 spinal nerve. All patients experienced immediate pain relief postoperatively. Microendoscopic partial resection of the sacral ala is an effective and minimally invasive surgical option for patients with extraforaminal entrapment of the L-5 spinal nerve.

Aged↗

PubMed2006

Pleomorphic xanthoastrocytoma of the spinal cord. Case report.

The authors present clinical, radiological, and pathological features in a patient with a pleomorphic xanthoastrocytoma (PXA) of the spinal cord. To their knowledge, this is only the second report of a spinal cord PXA. In addition they provide a review of the literature on these tumors.

Adult↗

PubMed2006

Pathognomonic radiological signs for predicting prognosis in patients with chronic atlantoaxial rotatory fixation.

OBJECT: The authors conducted a study to assess the correlation between radiological features and clinical courses in patients with chronic atlantoaxial rotatory fixation (AARF) and to determine diagnostic imaging signs for predicting prognosis. METHODS: There were 24 patients (eight boys and 16 girls) whose mean age was 7.8 years (range 4-14 years) and in whom AARF was diagnosed. The mean follow-up duration was 3.7 years (range 5 weeks-12 years). There were two groups of patients: 15 patients who visited the hospital less than 8 weeks after symptom (torticollis) onset comprised the acute group, and nine patients in whom the diagnosis of AARF was established later than 3 months after symptom onset comprised the chronic group. The chronic group was divided into two subgroups: those in whom the closed reduction could be achieved and those in whom it could not. Clinical data and radiographic studies, including plain radiographs and plain and three-dimensional (3D) computed tomography (CT) reconstructions, were reviewed retrospectively. A deformity of the superior C-2 facet joint was frequently observed in the group of patients with chronic AARF (p < 0.0001). This sign represented a risk factor for recurrent dislocation (p = 0.0003, Fisher exact test). Prominent lateral inclination of C-1 was an impeding factor for reduction of chronic AARF (p < 0.0001, analysis of variance with Fisher post hoc test). Greater than 20 degrees of lateral inclination of the atlas indicated an irreducible subluxation (p = 0.0023, Fisher exact test). CONCLUSIONS: Both facet joint deformity and lateral inclination observed on 3D CT reconstructions can be useful signs to predict the prognosis and the treatment of choice in patients with chronic AARFs.

Adolescent↗

PubMed2006

Postoperative factors affecting neurological recovery after surgery for cervical spondylotic myelopathy.

OBJECT: Many prognostic factors associated with surgery for cervical spondylotic myelopathy (CSM) have been detailed in the literature. All of these factors, however, are defined preoperatively. If it is possible to clarify factors influencing surgical results that can be modulated after surgery, then the overall results of surgery may improve. The purpose of this study was to elucidate such postoperative factors affecting neurological recovery. METHODS: The authors assessed the surgical outcomes obtained in 183 patients with CSM who underwent expansive open-door laminoplasty between 1993 and 2004 and who underwent follow up for a minimum of 1 year. They classified the cases into two groups according to the degree of neurological recovery: an excellent recovery group, comprising patients in whom the recovery rates were greater than 75%, and a poor recovery group, composed of patients in whom the recovery rates were lower than 30%. Comparisons of various clinical and imaging parameters revealed that the mean age at surgery was significantly lower in patients in the excellent recovery group than that in the poor recovery group. Therefore, the authors repeated the same analyses after adjustment for age. Postoperative cervical range of motion (ROM) was significantly more reduced in the excellent recovery group than in the poor recovery group. There was a significant positive correlation between reduced cervical ROM and recovery rate in the poor recovery group. CONCLUSIONS: Dynamic stress may ameliorate functional recovery of the degenerated spinal cord even after sufficient decompression. Postoperative preservation of cervical ROM may not always be beneficial for neurological recovery in patients with CSM.

Age Distribution↗

PubMed2005

Lecithinized superoxide dismutase (PC-SOD) improved spinal cord injury-induced motor dysfunction through suppression of oxidative stress and enhancement of neurotrophic factor production.

PC-SOD (lecithinized superoxide dismutase) is a derivative of human Cu, Zn-SOD conjugated with 4 molecules of lecithin, yet having the enzyme activity of scavenging superoxide anion (O2-). Intravenous administration of PC-SOD promoted the recovery from spinal cord injury (SCI)-induced motor dysfunction in a dose-dependent manner in rat model, when evaluated by BBB (Basso Beattie Bresnahan) score. Even when given at 24 h after SCI, PC-SOD (1 mg/kg) significantly improved motor dysfunction. Distribution study demonstrated that PC-SOD gradually accumulated to the injured site. Enzyme-linked immunoassay revealed that PC-SOD prevented quantitative loss of neurons, astrocytes, and oligodendrocytes. PC-SOD inhibited SCI-induced oxidative stress, such as the decrease of free sulfhydryl residue, acetylcholine esterase activity, and the increase of lipid peroxidation. PC-SOD increased the production of neuroprotective factors. HIF-1alpha gene expression increased following SCI, and PC-SOD further increased it. In conclusion, PC-SOD gradually accumulated and retained at the damaged site to scavenge excessive O2-, and suppressed neuronal death through reducing oxidative stress, increasing neuroprotective factor production and HIF-1alpha gene expression.

Animals↗

PubMed2005

Efficient production of 2-pyrone 4,6-dicarboxylic acid as a novel polymer-based material from protocatechuate by microbial function.

Sphingomonas paucimobilis SYK-6, which can degrade various low molecular weight compounds derived from plant polyphenols such as lignin, lignan, and tannin, metabolizes these substances via 2-pyrone-4,6-dicarboxylic acid (PDC). We focused on this metabolic intermediate as a potential raw material for novel, bio-based polymers. We cloned the ligAB and ligC genes of SYK-6, which respectively encode protocatechuate 4,5-dioxygenase and 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase, into a broad host range plasmid vector, pKT230MC. The resulting plasmid, pDVABC, was introduced into the PpY1100 strain of Pseudomonas putida, and we found that PDC could be stably produced from protocatechuate and accumulated. In addition, we examined the efficiency of production of PDC from protocatechuate on a 5-L scale in a Luria-Bertani medium containing 100 mM glucose and determined that PDC was stably produced from protocatechuate to yield 10 g/L or more.

Bacterial Proteins↗

PubMed2005

Spinal kyphosis causes demyelination and neuronal loss in the spinal cord: a new model of kyphotic deformity using juvenile Japanese small game fowls.

STUDY DESIGN: Histologic changes in the spinal cord caused by progressive spinal kyphosis were assessed using a new animal model. OBJECTIVES: To evaluate the effects of chronic compression associated with kyphotic deformity of the cervical spine on the spinal cord. SUMMARY OF BACKGROUND DATA: The spinal cord has remarkable ability to resist chronic compression, however, delayed paralysis is sometimes seen following the development of spinal kyphosis. In the past, no animal model to clarify the mechanism of spinal cord damage due to spinal kyphotic deformity has been available. METHODS: Laminectomy and bilateral facetectomy at the C4-C5 level was performed in 52 Japanese small game fowls. Histologic changes in the spinal cord associated with progressive kyphotic deformity were examined at different time points after surgery in each animal. The degree of spinal cord flattening and the severity of demyelination in histologic sections were quantitatively evaluated using an image analyzer, and their association with the kyphotic angle was analyzed. Changes in the microvascular distribution in the spinal cord were also examined by microangiography. RESULTS: In all operated animals, progressive kyphosis developed reproducibly. The kyphotic angle increased gradually until 3 weeks after surgery and stabilized thereafter. There was a significant correlation between the kyphotic angle and the degree of spinal cord flattening. The spinal cord was compressed most intensely at the apex of the kyphosis, where demyelination of the anterior funiculus as well as neuronal loss and atrophy of the anterior horn were observed. Demyelination progressed as the kyphotic deformity became more severe, initially affecting the anterior funiculus and later extending to the lateral and then the posterior funiculus. Angiography revealed a decrease of the vascular distribution at the ventral side of the compressed spinal cord. CONCLUSIONS: Progressive kyphosis of the cervical spine resulted in demyelination of nerve fibers in the funiculi and neuronal loss in the anterior horn due tochronic compression of the spinal cord. These histologic changes seem to be associated with both continuous mechanical compression and vascular changes in the spinal cord.

Animals↗

PubMed2005

In vivo imaging of engrafted neural stem cells: its application in evaluating the optimal timing of transplantation for spinal cord injury.

Neural stem/progenitor cells (NSPCs) hold promise in neural tissue replacement therapy after spinal cord injury. However, understanding the survival time of grafted NSPCs and determining the extent of migration away from transplantation sites are essential for optimizing treatment regimens. Here, we used in vivo bioluminescence imaging to noninvasively assess the survival and residence time of transplanted NSPCs at the injury sites in living animals, and we used histologic analyses to assess cell integration and morphology. Third-generation lentiviral vectors enabled efficient transduction and stable expression of both luciferase and a variant of green fluorescent protein in primary cultured NSPCs. Signals from these cells were detectable for up to 10 months or more after transplantation into the injured spinal cords of C57BL/6J mice. Histological and functional data supported the imaging data and suggest that the timing of NSPC transplantation may be a key determinant of the fates and function of integrated cells since cell survival and migration depended on the time of transplantation relative to injury. Optimization of cell therapies can be greatly accelerated and refined by imaging, and the methods in the present study can be widely applied to various research fields of regeneration medicine, including transplantation study.

Animals↗

PubMed2005

Molecular cloning of developmentally specific genes by representational difference analysis during the fruiting body formation in the basidiomycete Lentinula edodes.

To understand molecular mechanisms of the fruiting body development in basidiomycetes, we attempted to isolate developmentally regulated genes expressed specifically during the fruiting body formation of Lentinula edodes (Shiitake-mushroom). cDNA representational difference analysis (cDNA-RDA) between vegetatively growing mycelium and two developmental substages, primordium and mature fruiting body, resulted in an isolation of 105 individual genes (51 in primordium and 54 in mature fruiting body, respectively). A search of homology with the protein databases and two basidiomycetous genomes in Phanerochaete chrysosporium and Coprinopsis cinerea revealed that the obtained genes encoded various proteins similar to those involved in general metabolism, cell structure, signal transduction, and responses to stress; in addition, there were apparently several metabolic pathways and signal transduction cascades that could be involved in the fruiting body development. The expression products of several genes revealed no significant homologies to those in the databases, implying that those genes are unique in L. edodes and the encoding products may possess possible functions in the course of fruiting body development. RT-PCR analyses revealed that 20 candidates of the obtained genes were specifically or abundantly transcribed in the course of the fruiting body formation, suggesting that the obtained genes in this work play roles in fruiting body development in L. edodes.

Agaricales↗

PubMed2005

Targeted expression of anti-apoptotic protein p35 in oligodendrocytes reduces delayed demyelination and functional impairment after spinal cord injury.

Functional impairment after spinal cord injury (SCI) is attributed to neuronal cell necrosis death and axonotmesis, with further worsening caused by the accompanying apoptosis of myelin-forming oligodendrocytes (OLGs). However, it is unclear as to how much OLG apoptosis contributes to functional impairment. To address this issue, we used transgenic mice characterized by the targeted expression of p35, a broad-spectrum caspase inhibitor, in OLGs using the cre/loxP system (referred to as cre/p35 transgenic mice). In this study, we examined the motor function and histopathologic changes after a contusive thoracic spinal cord injury in the cre/p35 transgenic mice. A larger number of OLGs and a lesser extent of demyelination were observed after SCI in the cre/p35 transgenic mice than in the control cre mice, which did not carry the p35 transgene. Furthermore, the motor function of the hindlimbs recovered to a significantly better degree in the cre/p35 transgenic mice than in the control cre mice. Thus, the inhibition of OLG apoptosis decreased the extent of functional impairment after SCI. These findings suggest that the inhibition of OLG apoptosis may be a potential treatment for SCI.

Animals↗