Toshio Masuzawa

Jichi Medical University, Totigi, Tochigi, Japan

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Publications (128)283.21 Total impact

  • Masaru Kanda · Soji Shinoda · Toshio Masuzawa
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    ABSTRACT: A 48-year-old woman with a 29-year history of pulseless disease presented with subarachnoid hemorrhage caused by a rare ruptured intracranial aneurysm of the right vertebral-posterior inferior cerebellar artery. The aneurysm was successfully clipped. Pulseless disease is a chronic and nonspecific vasculitis involving mainly the aorta and its main branches such as the carotid, subclavian, vertebral, and coronary arteries. The cervical vessels are mostly affected in Japanese patients. Almost all patients have ischemic disorders of the involved vessels, manifesting as syncope, visual disturbance, or a faint or absent pulse. The mechanisms responsible for pulseless disease and intracranial aneurysms are likely to be different.
    No preview · Article · Aug 2004 · Neurologia medico-chirurgica
  • Eiji Matsumoto · Toshio Masuzawa · Yosikazu Nakamura
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    ABSTRACT: The frequency at which unruptured cerebral aneurysms are detected has increased due to advances in low- or non-invasive diagnostic techniques. Despite the recent improvements in surgical and medical management of aneurysmal subarachnoid hemorrhages, however, the overall case-fatality rate of this disease is still high. To reduce it, the natural history of unruptured cerebral aneurysms should be better understood. The subjects consisted of 156 patients with unruptured cerebral aneurysms who had been admitted to the Department of Surgical Neurology, Jichi Medical School Hospital or Jichi Medical School Ohmiya Medical Center, Japan, between January 1989 and December 1998. All of the patients were classified according to the process by which aneurysms had been detected. The expected number of deaths was calculated by using age- and sex-specific mortality rates obtained from the vital statistics. A standardized mortality ratio and 95% confidence interval were calculated by using the expected and observed numbers of deaths. The standardized mortality ratios differed among the groups according to the process of detecting aneurysms. The incidence rate of rupture of unruptured cerebral aneurysms was 1.3 per 100 person-years. The annual rupture rate of unruptured cerebral aneurysms was higher than previously reported. The survival rate of the group that underwent surgical treatment for unruptured cerebral aneurysms was higher than that of the untreated group. The annual rupture rate of unruptured cerebral aneurysms may be higher than previously reported.
    No preview · Article · Dec 2003 · Journal of Epidemiology
  • Yasushi Haga · Hiroyuki Cho · Souji Shinoda · Toshio Masuzawa
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    ABSTRACT: A 58-year-old woman presented with Currarino triad manifesting as recurrent meningitis. Currarino triad is a combination of a presacral mass, a congenital sacral bony abnormality, and an anorectal malformation, which is caused by dorsal-ventral patterning defects during embryonic development. She had a history of treatment for anal stenosis in her childhood. Radiographic examinations demonstrated the characteristic findings of Currarino triad and a complicated mass lesion. The diagnosis was recurrent meningitis related to the anterior sacral meningocele. Neck ligation of the meningocele was performed via a posterior transsacral approach after treatment with antibiotics. At surgery, an epidermoid cyst was observed inside the meningocele. The cyst content was aspirated. She suffered no further episodes of meningitis. The meningitis was probably part of the clinical course of Currarino triad. Radiography of the sacrum and magnetic resonance imaging are recommended for patients with meningitis of unknown origin. The early diagnosis and treatment of this condition are important.
    No preview · Article · Nov 2003 · Neurologia medico-chirurgica
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    T Yamaguchi · T Okada · K Takeuchi · T Tonda · M Ohtaki · S Shinoda · T Masuzawa · K Ozawa · T Inaba
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    ABSTRACT: Herpes simplex virus thymidine kinase (HSV-tk)/gancyclovir (GCV) therapy has the ability to inhibit tumor formation in animal models but the results of clinical trials have been disappointing. To improve the performance of tk/GCV therapy, we tried combination therapy designed to enhance its cytotoxic effects by introducing genes that induce apoptosis of the tumor cells through different pathways. We concentrated our efforts on the use of Bim, a BH3-only member of death activators in the Bcl-2 superfamily, because Bim is not involved in the pathways through which HSV-tk/GCV therapy induces apoptosis in malignant glioma cells. Among three alternative splicing variants, BimEL, BimL, and BimS, BimS lacks the binding domain for the dynein light chain LC8, which negatively regulates the proapoptotic function of BimEL and BimL. All four malignant glioma cell lines, U251, A172, T-430, and U373 underwent cell death after transfer of BimS using an adenovirus vector (AVC2). Intriguingly, combination of AVC2-BimS with AVC2-tk markedly increased the sensitivity of U251 cells to GCV both in vitro and in vivo. In contrast, AVC2-BimL did not induce significant cell death. These results indicated that BimS had the ability to improve the efficiency of HSV-tk/GCV therapy in the treatment of malignant glioma and suggested that the targeting of different proapoptotic pathways may be a useful strategy for the development of an effective gene therapy approach to treatment.
    Full-text · Article · Apr 2003 · Gene Therapy
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    ABSTRACT: The ST2 gene, which is specifically induced by growth stimulation in fibroblasts, encodes interleukin-1 receptor-related proteins and is widely expressed in hematopoietic, helper T, and various cancer cells. However, the physiological as well as pathological functions of the ST2 gene products are not yet fully understood. In this study, we analyzed the expression of the ST2 gene in human glioma cell lines and human brain tumor samples with real-time polymerase chain reaction method, the results of which revealed that the expression level of the ST2 gene in glioma cell lines and glioblastoma samples is significantly lower than that in a fibroblastic cell line, TM12, and benign brain tumors, suggesting the reverse relationship between malignancy and ST2 expression. As we could not detect the soluble ST2 protein in the culture fluid of the T98G glioblastic cell line by ELISA, we established stable transformants of T98G that continuously produce and secrete the ST2 protein, in order to study the effect of the ST2 protein on malignancy. Although we could not detect a remarkable difference in proliferation between transformants and control cells in conventional tissue culture dishes, the efficiency of colony formation in soft agar was significantly decreased in the case of cells that continuously produce the ST2 protein. Furthermore, inhibition of colony formation in soft agar was observed in wild-type T98G cells when purified soluble ST2 protein was added to the culture, in a dose-dependent manner. Taken together, the results suggest that the expression of ST2 suppressed the anchorage-independent growth and malignancy.
    Preview · Article · Feb 2003 · European Journal of Biochemistry
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    ABSTRACT: We studied the effects of a wasp toxin beta-pompilidotoxin (beta-PMTX) on rat hippocampal CA1 interneurons by the current-clamp technique. The firing patterns of pyramidal neurons and pyramidale interneurons were not affected by beta-PMTX, but in oriens and radiatum interneurons, beta-PMTX converted the action potentials to prolonged depolarizing potentials by slowing the inactivation of Na(+) channels. In lacunosum moleculare interneurons, beta-PMTX induced initial bursting spikes followed by block of succeeding spikes. Comparison of beta-PMTX with a sea anemone toxin, ATX II, revealed that ATX II altered the firing properties of pyramidal neurons and pyramidale interneurons that were unchanged by beta-PMTX. Our results suggest that beta-PMTX modulates Na(+) currents in CA1 interneurons differently in various CA1 neurons and the toxin is useful to classify Na(+) channel subtypes.
    No preview · Article · Sep 2002 · Neuroscience Letters
  • Eiji Matsumoto · Souji Shinoda · Toshio Masuzawa · Kouichi Nakamura
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    ABSTRACT: Screening for unruptured cerebral aneurysms (UCAs) using magnetic resonance imaging (MRI) and angiography (MRA) is prevalent in Japan. To reveal the prevalence of UCAs found during screening, we collected data of the results in 1999, in Tochigi prefecture. In the prefecture, of which the population was about 2 million, 26 institutions had been established in 1999, and 5,222 persons had been screened. These corresponded to 0.26% of all inhabitants of Tochigi prefecture. Of the 26 institutions, 24 cooperated in this study, and data was collected for 4,961 persons. We investigated the prevalence of UCAs, and compared it with that of subarachnoid hemorrhage (SAH) in Japan using the existing statistics. The UCAs were found in 143 (2.9%) of the 4,961 cases, 69 men and 74 women, with a mean age of 59.2 years. The prevalence of UCAs at screening and the prevalence of SAH in Japan co-relate in that this prevalence increases with age in both UCAs and SAH. However, after the age of 75, the provalence of SAH decreases. People found with UCAs at screening were mainly in their 50's, but the member of those found with SAH increased gradually after that age. The rate of screening of women was lower than that of men, although both the prevalence of UCAs at screening and SAH of women is higher than that of men. We recommend that middle-aged persons, in their 40's and older, should request screening for UCAs.
    No preview · Article · Sep 2002 · No shinkei geka. Neurological surgery
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    ABSTRACT: A 65-year-old man developed pancreatic and pubic tumors 22 years after craniotomy for a left sphenoid ridge tumor. The histological finding of the primary sphenoid ridge tumor was meningotheliomatous meningioma. The histological appearance of the biopsy specimen of the pubic tumor was hemangiopericytoma. The recurrent intracranial tumor was treated by radiosurgery, and the metastatic tumors were treated by conventional irradiation. Intracranial tumors rarely metastasize outside the central nervous system, except for meningeal hemangiopericytomas. This case indicates that meningeal hemangiopericytoma may metastasize many years after the initial onset and requires long-term follow up.
    No preview · Article · Aug 2002 · Neurologia medico-chirurgica
  • Masaru Kanda · Hidenobu Tanaka · Soji Shinoda · Toshio Masuzawa
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    ABSTRACT: A case of recurrent pilocytic astrocytoma with leptomeningeal dissemination (LMD) is described. A cerebellar tumor was diagnosed in a 3-year-old boy, in whom resection was performed. When the boy was 6 years of age, recurrence was treated with surgery and local radiotherapy. At age 13 years, scoliosis was present, but the patient was asymptomatic. Twelve years after initial surgery LMD was demonstrated in the lumbar spinal region without recurrence of the original tumor. This tumor also was subtotally removed. During the procedure, a hematoma was observed adjacent to the tumor, but the border was clear. Histological examination of the spinal cord tumor showed features similar to those of the original tumor. There were no tumor cells in the hematoma. The MIB-1 labeling index indicated no malignant change compared with the previous samples. Radiotherapy was performed after the surgery. The importance of early diagnosis and management of scoliosis is emphasized, and the peculiar pattern of dissemination of the pilocytic astrocytoma and its treatment are reviewed.
    No preview · Article · Aug 2002 · Neurosurgical FOCUS
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    ABSTRACT: A 65-year-old man developed pancreatic and pubic tumors 22 years after craniotomy for a left sphenoid ridge tumor. The histological finding of the primary sphenoid ridge tumor was meningotheliomatous meningioma. The histological appearance of the biopsy specimen of the pubic tumor was hemangiopericytoma. The recurrent intracranial tumor was treated by radiosurgery, and the metastatic tumors were treated by conventional irradiation. Intracranial tumors rarely metastasize outside the central nervous system, except for meningeal hemangiopericytomas. This case indicates that meningeal hemangiopericytoma may metastasize many years after the initial onset and requires long-term follow up.
    No preview · Article · Jul 2002 · Neurologia medico-chirurgica
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    ABSTRACT: GFAP (glial fibrillary acidic protein) is an intermediate filament protein found exclusively in the astrocytes of the central nervous system. We studied the role of GFAP in the neuronal degeneration in the hippocampus after transient ischemia using knockout mice. Wild-type C57 Black/6 (GFAP(+/+)) mice and mutant (GFAP(-/-)) mice were subjected to occlusion of both carotid arteries for 5-15 min. Hippocampal slices were prepared 3 days after reperfusion and the field excitatory postsynaptic potentials (fEPSP) in the CA1 were recorded. High frequency stimulation induced robust long-term potentiation (LTP) in GFAP(-/-), as in GFAP(+/+) mice. After ischemia, however, the LTP in GFAP(-/-) was significantly depressed. Similarly, paired pulse facilitation (PPF) displayed little difference between GFAP(+/+) and GFAP(-/-), but after ischemia, the PPF in GFAP(-/-) showed a depression. Histological study revealed that loss of CA1 and CA3 pyramidal neurons after ischemia was marked in GFAP(-/-). MAP2 (dendritic) immunostaining in the post-ischemic hippocampus showed little difference but NF200 (axonal) immunoreactivity was reduced in GFAP(-/-). S100beta (glial) immunoreactivity was similar in the post-ischemic hippocampus of the GFAP(+/+) and GFAP(-/-), indicating that reactive astrocytosis did not require GFAP. Our results suggest that GFAP has an important role in astrocyte-neural interactions and that ischemic insult impairs LTP and accelerates neuronal death.
    Full-text · Article · Jan 2002 · Journal of Neuroscience Research
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    ABSTRACT: We examined the effects of β-pompilidotoxin (β-PMTX), a neurotoxin derived from wasp venom, on synaptic transmission in the mammalian central nervous system (CNS). Using hippocampal slice preparations of rodents, we made both extracellular and intracellular recordings from the CA1 pyramidal neurons in response to stimulation of the Schaffer collateral/commissural fibers. Application of 5–10 μM β-PMTX enhanced excitatory postsynaptic potentials (EPSPs) but suppressed the fast component of the inhibitory postsynaptic potentials (IPSPs). In the presence of 10 μM bicuculline, β-PMTX potentiated EPSPs that were composed of both non-NMDA and NMDA receptor-mediated potentials. Potentiation of EPSPs was originated by repetitive firings of the presynaptic axons, causing summation of EPSPs. In the presence of 10 μM CNQX and 50 μM APV, β-PMTX suppressed GABAA receptor-mediated fast IPSPs but retained GABAB receptor-mediated slow IPSPs. Our results suggest that β-PMTX facilitates excitatory synaptic transmission by a presynaptic mechanism and that it causes overexcitation followed by block of the activity of some population of interneurons which regulate the activity of GABAA receptors.
    No preview · Article · Dec 2001 · Neuroscience Research
  • Yuichi Tanaka · Toshio Masuzawa · Mitsuru Saito · Takeshi Yamada
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    ABSTRACT: The mechanisms of the inhibitory effects of verapamil and nitroglycerin on vasospasm were investigated by measuring cytosolic Ca2+ level ([Ca2+]i) and muscle tension in 28 normal specimens and 28 spastic vascular specimens of smooth muscle. Experimental vasospasm was produced by the two-hemorrhage method in the canine basilar artery. [Ca2+]i and tension were recorded simultaneously with a fluorimeter using fura-2. High K+ concentration (72.4 mM) and U-46619 (thromboxane A2 analogue, 10(-8) M) were used as stimulants, and the inhibitory effects of verapamil or nitroglycerin on muscle contraction and increased [Ca2+]i were examined. Verapamil inhibited [Ca2+]i and contraction in high K+ concentration-stimulated arteries. Verapamil inhibited [Ca2+]i more strongly than contraction in U-46619-stimulated arteries. There were no significant differences in the effects of verapamil in the control and vasospasm groups. Nitroglycerin inhibited contraction with little effect on [Ca2+]i in high K+ concentration-stimulated arteries in both the control and vasospasm groups. Nitroglycerin inhibited contraction with little effect on [Ca2+]i in U-46619-stimulated arteries and the inhibitory effect was weaker in the vasospasm group than in the control group. The inhibitory effects of verapamil on muscle tension and [Ca2+]i in vasospastic vessels were as strong as those in normal vessels. In contrast, the inhibitory effects of nitroglycerin were reduced in vasospastic vessels. Increased Ca2+ sensitivity in vasospastic vessels may have reduced the inhibitory effects of nitroglycerin.
    No preview · Article · Jun 2001 · Neurologia medico-chirurgica
  • Mutsumi Nagai · Toshio Masuzawa
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    ABSTRACT: Recently, studies on vaccination with tumor cells genetically engineered to produce monocyte chemoattractant protein-1 (MCP-1) have provided some encouragement. These studies have shown infiltration of certain types of lymphocytes at the tumor site. However, natural killer (NK) cells have not yet been assessed. We obtained a human malignant glioma cell line producing human MCP-1 constitutively by transfection of MCP-1 cDNA. We then test the effect of vaccination with the MCP-1 transfectant on nude mice. Although vaccination with MCP-1 transfectant did not reduce the tumor in our study, it was associated with the infiltration of large numbers of NK cells and monocytes at the tumor site. The site of vaccination also showed large numbers of monocytes. NK cells were detected with anti-asialo GM1 antibody, and monocytes were detected immunohistochemically with F4/80. We assumed that infiltrating monocytes at the site of vaccination could promote the infiltration of monocytes and NK cells into the tumor site without T-cell mediated transduction because the host lacked T-cell function.
    No preview · Article · May 2001 · International Immunopharmacology
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    ABSTRACT: We analyzed the disorder of water metabolism in a 32 year-old female with chronic hypernatremia. She had meningitis at 4 years, and ventriculo-peritoneal shunt operation at 13 years because of normal pressure hydrocephalus. At 14 years hypernatremia of 166 mmol/l was initially found and thereafter hypernatremia ranging from 150 to 166 mmol/l has been persisted for the last 18 years. Physical and laboratory findings did not show dehydration. Urine volume was 750-1700 ml per day and urinary osmolality (Uosm) 446-984 mmol/kg, suggesting no urinary concentrating defect. Plasma arginine vasopressin (AVP) levels ranged from 0.4 to 1.2 pmol/l despite hyperosmolality of 298 through 343 mmol/kg under ad libitum water drinking. There was no correlation between plasma osmolality (Posm) and plasma AVP levels, but Uosm had a positive correlation with Posm (r=0.545, P < 0.05). Hypertonic saline (500 NaCl) infusion after a water load increased Uosm from 377 to 679 mmol/kg, and plasma AVP from 0.2 to 1.3 pmol/l. There was a positive correlation between Posm and plasma AVP levels in the hypertonic saline test (r=0.612, P<0.05). In contrast, an acute water load (20 ml/kg BW) verified the presence of impaired water excretion, as the percent excretion of the water load was only 8.5% and the minimal Uosm was as high as 710 mmol/kg. Urinary excretion of aquaporin-2 remained low in concert with plasma AVP levels. No abnormality in pituitary-adrenocortical function was found. These results indicate that marked hypernatremia is derived from partial central diabetes insipidus and elevated threshold of thirst, and that enhanced renal water handling may contribute to maintenance of body water in the present subject.
    No preview · Article · May 2001 · Endocrine Journal
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    ABSTRACT: Growth hormone (GH) deficiency has been regarded as a principal determinant for growth failure following bone marrow transplantation (BMT). We herein analyzed final height and GH secretion in the patients who received BMT during childhood. The study on final height in 30 patients (23 males; 19 with malignant disease) who underwent BMT before or at the onset of puberty showed the following findings: (1) Final height SD score (SDS) significantly decreased compared to pretreatment height SDS. (2) Patients who underwent BMT before the age of 10 years showed significantly greater reduction in height SDS compared to those who received after the age of 10 years. (3) The type of disease or a difference in preconditioning regimen did not influence the outcome of growth. (4) No patient showed GH deficiency. The study on GH secretion included 71 patients who had been followed for more than 5 years and who underwent insulin tolerance test more than twice following BMT. Thirteen patients experienced poor GH response at least once. Two of these patients had poor GH response repeatedly. In conclusion, children who undergo BMT at younger age have a higher risk of growth failure, and GH deficiency is not a major contributing factor for growth impairment following BMT.
    Preview · Article · Jan 2001 · Endocrine Journal
  • T. Miyawaki · G. Kusaka · S. Shinoda · T. Masuzawa
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    ABSTRACT: Primary involvement of the spinal cord in malignant lymphoma is uncommon, with only 22 cases having been confirmed in the literature. We describe a 41-year-old man with symptoms attributable to spinal cord lesion. The presenting sympton was spastic paresis and dysesthesia of the lower extremities, followed by urinary incontinence. Radiological examinations, including magnetic resonance imaging (MRI) with gadolinium (Gd-DTPA), revealed an intramedullary tumor at the levels of Th7-9. Laminectomy was performed with direct examination of the spinal cord at the levels of Th8-9. A biopsy specimen was obtained, and pathological examination revealed non-Hodgkin malignant lymphoma with B-cell surface marker. Radiation therapy was administered to the spinal lesion at the levels of Th4-12. The total dose was 40 Gy. Result of physical examination gradually improved, and MRI with Gd-DTPA showed no residual tumor. In addition to this case report, we review the literature on primary lymphomas of primary spinal intramedullary malignant lymphoma.
    No preview · Article · Jan 2001 · Japanese Journal of Neurosurgery

  • No preview · Article · Sep 1999 · European Journal of Cancer
  • H Yokota · S Shinoda · T Masuzawa · M Kawano · M Katoh · M Suzukawa
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    ABSTRACT: Nine patients with CNS damage who had been transferred to our critical care unit were treated with a commercially available kit for percutaneous dilational tracheostomy (PDT). The mean procedure time was about 11 minutes, and the perioperative complication rate was 22% (2/9). Only one complication, wound infection, occurred, and the patient was cured with conventional therapy. On the other hand, premature extubation of the translaryngeal tube occurred in one case. Long-term complications like tracheal stenosis and tracheal malacia were not experienced in two patients. They were discharged from the hospital after decannulation. In conclusion, the advantages of PDT include a short procedure time, the ability to perform the procedure at the bedside, and reduced stimulation of the trachea. Because of the safety and simplicity of the procedure, we recommend PDT for patients with CNS damage.
    No preview · Article · Mar 1999 · No shinkei geka. Neurological surgery

  • No preview · Article · Dec 1998 · Neuroscience Research

Publication Stats

1k Citations
283.21 Total Impact Points


  • 1982-2003
    • Jichi Medical University
      • • Department of Physiology
      • • Department of Neurosurgery
      • • Department of Pediatrics
      • • Department of Radiology
      Totigi, Tochigi, Japan
  • 1996
    • University of Cambridge
      Cambridge, England, United Kingdom
    • The University of Tokyo
      • Division of Internal Medicine
      Tōkyō, Japan