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Kenichi Matsumoto

Publications and source records attributed to Kenichi Matsumoto.

12 recordsLinked to original sources
PubMed2006

An astroblastoma case associated with loss of heterozygosity on chromosome 9p.

The tumorigenesis of astroblastomas has not yet been elucidated on the basis of histopathological studies, and genetic studies may be useful for obtaining additional information regarding the tumorigenesis of these tumors. Here, we report an astroblastoma case in which a genetic analysis was performed. A 16-year-old female with a progressive headache was found to have a demarcated cystic tumor with a mural nodule in the right parietal lobe. Total removal of the tumor was achieved and a histological examination verified that the tumor was an astroblastoma. A genetic analysis using microsatellite markers revealed loss of heterozygosity (LOH) on chromosome 9p. The postoperative course was uneventful and, to date, she has been followed up for 2 years with no signs of recurrence. This is the first reported case of an astroblastoma in which LOH was detected on 9p. Based on this result, the tumorigenesis of astroblastomas is discussed.

Adolescent↗
PubMed2005

Number of Fe ion traversals through a cell nucleus for mammalian cell inactivation near the bragg peak.

HeLa and CHO-K1 cells were irradiated with Fe ions (1.14 MeV/nucleon) near the Bragg peak to determine how many ion traversals through a cell nucleus are necessary to induce cell inactivation. The ion traversals through a cell nucleus were visualized by immunostaining the phosphorylated histone H2AX (gamma-H2AX), as an indicator of DNA double strand breaks (DSBs), to confirm that DSBs are actually induced along every Fe ion traversal through the nucleus. The survival curves after irradiation with Fe ions decreased exponentially with the ion fluence without a shoulder. The inactivation cross sections calculated from the slope of the survival curves and the standard errors were 96.9 +/- 1.8 and 57.9 +/- 5.4 microm2 for HeLa and CHO-K1 cells, respectively, corresponding to 0.442 and 0.456 of the mean value of each cell nucleus area. Taking the distribution of the cell nucleus area into consideration with an equation proposed by Goodhead et al. (1980), which calculates the average number of lesions per single ion track through the average area of a sensitive organelle (mainly nucleus), these two ratios were converted to 0.705 and 0.659 for HeLa and CHO-K1 cells, respectively. These ratios were less than one, suggesting that the average numbers of lethal hits per cell produced by a single ion traversal were less than one. We thus considered two possible explanations for ion traversals of more than one, necessary for cell inactivation.

Animals↗
PubMed2005

[Case of central nervous system lymphoma metastasized to breast after remission by methotrexate chemotherapy].

We report a case of primary central nervous system lymphoma (PCNSL) who responded well to initial systemic chemotherapy, but subsequently developed breast metastasis with local recurrence in the brain 27 months after complete remission. The 53-year-old female suddenly felt weakness in her left extremity. She was transferred to the emergency ward in our hospital. Neurological examination on admission showed disorientated state and mild hemiparesis. Brain MRI showed a well enhanced round lesion in the right basal ganglia with perifocal edema. A stereotactic biopsy of the tumor made a diagnosis of classic diffuse non-Hodgkin's B-cell type lymphoma. She received chemotherapy with a high-dose methotrexate under a condition of 20% of Karnofsky Performance Status (KPS). She enjoyed a useful life for about 5 years (KPS; 60-70%). Both recurrent and metastatic lesions responded poorly to various aggressive multiagent regimens of chemotherapy. An intensive initial treatment for the primary lesion and closely monitoring of the whole body at regular intervals are necessary for ensuring a long useful life.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2004

Optimum threshold setting for a positron-sensitive probe with background rejection capability.

In a positron-sensitive probe composed of a plastic scintillator and a bismuth germanate (BGO), scattered annihilation photons in the plastic scintillator become background counts. Although these scattered annihilation photons can be rejected by higher threshold level settings for the scintillation pulse of the plastic scintillator and for that of the BGO, the system sensitivity is reduced. We have theoretically and experimentally optimized the threshold levels for both the plastic scintillator and the BGO. After calculating the energy loss in the plastic scintillator and the BGO for the scattered annihilation photons, we measured the background counts of a positron-sensitive probe by changing these threshold levels. Results revealed that one optimum threshold setting of the positron-sensitive probe was 0.3 of the peak level of the pulse for the plastic scintillator and 0.7 of that for the BGO. With these threshold levels, the background counts could be decreased to less than 0.2% of the true positron counts.

Algorithms↗
PubMed2004

Glossopharyngeal neuralgia due to an epidermoid tumour in the cerebellopontine angle.

A 42-year-old female presented with typical glossopharyngeal neuralgia. Magnetic resonance imaging demonstrated an epidermoid tumour in the left cerebellopontine angle. Surgery showed that the tumour was compressing the glossopharyngeal nerve but no vessel was related to the nerve. The tumour was subtotally removed and after surgery the patient showed a complete relief of pain. This is a very rare case of glossopharyngeal neuralgia alone due to an epidermoid tumour.

Adult↗
PubMed2004

Accumulation of MDM2 in pleomorphic xanthoastrocytomas.

The molecular genetic basis and the tumorigenic mechanism of pleomorphic xanthoastrocytoma (PXA) still remain to be elucidated. The amplification of the mdm2 gene and accumulation of the MDM2 protein, which is considered to be one of the major cellular regulators of p53-mediated cell growth control, were studied in eight specimens of PXA obtained from five patients. All of the PXA samples showed at least focal immunopositivity for MDM2. However, none of the samples showed mdm2 gene amplification. These results suggest that accumulation of MDM2 without gene amplification may be one of the major molecular events occurring in the tumorigenesis of PXA.

Adolescent↗
PubMed2003

A comparative immunohistochemistry of O6-methylguanine-DNA methyltransferase and p53 in diffusely infiltrating astrocytomas.

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) removes mutagenic adducts from the O6 position of guanine, thereby protecting the genome against guanine : cytosine to adenine : thymine transition and, meanwhile, conferring tumor resistance to many anti-cancer alkylating agents commonly used in the treatment of malignant gliomas. Studies on the involvement of p53 protein in expression of the MGMT gene have provided conflicting results regarding the relation between p53 protein and MGMT gene expression. To examine the potential immunostaining pattern of MGMT expression and to evaluate the possible relationship between p53 and MGMT regulation, we assessed MGMT and p53 accumulation on 35 cases of diffusely infiltrating astrocytomas. With a few cases showing cytoplasmic staining, MGMT accumulation was mainly nuclear. The percentage of labeled tumor cells was lower in high-grade astrocytomas than in low-grade astrocytomas (P < 0.05). Additionally, p53-immunopositive tumor cells were usually immunonegative to MGMT. Thus, it is suggested that MGMT expression is reduced during malignant transformation of diffusely infiltrating astrocytomas, and that mutant p53 protein might be associated with down regulation of the MGMT expression.

Adolescent↗
PubMed2003

Reversible non-thrombotic occlusion of the superior sagittal sinus caused by metastatic malignant lymphoma--case report.

A 57-year-old female presented with intracranial hypertension secondary to non-thrombotic superior sagittal sinus occlusion manifesting as acute onset of headache, vomiting, and disorientation. She had a history of intrapelvic malignant lymphoma. Neuroimaging and tumor biopsy revealed that both the superior sagittal sinus and the straight sinus were occluded by metastatic deposits of malignant lymphoma. Her clinical symptoms were remarkably improved by irradiation and chemotherapy, and the affected sinuses were angiographically recanalized.

Brain Neoplasms↗
PubMed2002

Hypertrophic pachymeningitis as a result of a retropharyngeal inflammatory pseudotumor: case report.

OBJECTIVE AND IMPORTANCE: An extremely rare case of a patient with hypertrophic pachymeningitis that resulted from an inflammatory pseudotumor of retropharynx is described. CLINICAL PRESENTATION: A 59-year-old man with a 9-year history of retropharyngeal inflammatory pseudotumor sought care for severe headache and multiple cranial nerve palsies. Magnetic resonance imaging and computed tomographic scans revealed pachymeningeal enhancement and obstructive hydrocephalus attributable to marked dural thickening around the foramen magnum. INTERVENTION: Decompression of the foramen magnum, C1 laminectomy, and meningeal biopsy were performed. The histological examination of the biopsy specimen revealed chronic inflammatory infiltrate in the hypertrophic dura mater. Corticosteroid pulse therapy was subsequently completed. Clinical and neuroradiological findings improved remarkably. CONCLUSION: A new case of hypertrophic pachymeningitis as a result of a retropharyngeal inflammatory pseudotumor is presented. We review and discuss the clinical features and the pathogenic mechanisms of hypertrophic pachymeningitis.

Granuloma, Plasma Cell↗
PubMed2002

Symptomatic spinal extramedullary mass lesion secondary to chronic overdrainage of ventricular fluid--case report.

A 69-year-old man presented with progressive nuchal pain and spastic gait 2 years after undergoing ventriculoperitoneal (VP) shunting for a pineal astrocytoma with obstructive hydrocephalus. The neurological manifestations were compatible with radiculomyelopathy caused by an upper cervical lesion. Magnetic resonance imaging showed an enhanced extramedullary mass lesion tightly constricting the upper cervical spinal cord. The pressure of the shunt system was 150 mmH2O, and lumbar puncture revealed normal cerebrospinal fluid (CSF) pressure of 170 mmH2O. After removal of the shunt system, the clinical symptoms and neuroradiological findings markedly improved. This symptomatic spinal mass lesion was thought to be formed secondary to chronic depletion of ventricular CSF through the VP shunt.

Aged↗
PubMed2002

Intramedullary subependymoma occupying the right half of the thoracic spinal cord--case report.

A 37-year-old female presented with a rare spinal subependymoma manifesting as progressive weakness of her right lower extremity over an 8-month period. She had a 10-year history of back pain and urinary disturbance. Magnetic resonance imaging showed diffuse enlargement of the spinal cord from T-2 to T-7 on the T1-weighted images. The enlarged spinal cord was divided into two compartments by a vertical septum-like structure on the T2-weighted images. The tumor occupied the right half of the thoracic spinal cord, and was totally removed through a laminectomy from T-2 to T-7. The histological diagnosis of the resected specimen was subependymoma. Subependymomas are slow-growing tumors usually found in the ventricular system. Spinal subependymomas are difficult to distinguish from other intramedullary spinal tumors based on neuroradiological findings. Subependymomas are surgically curable tumors, so if the tumor is well demarcated and a subependymoma is indicated, an attempt should be made to totally remove the tumor.

Adult↗