T Masuzawa

Jichi Medical University, Totigi, Tochigi, Japan

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Publications (115)236.29 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.
    Neurologia medico-chirurgica 08/2004; 44(7):363-7. · 0.65 Impact Factor
  • 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.
    Journal of Epidemiology 12/2003; 13(6):289-95. · 2.86 Impact Factor
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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.
    Neurologia medico-chirurgica 11/2003; 43(10):505-8. · 0.65 Impact Factor
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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.
    European Journal of Biochemistry 02/2003; 270(1):163-70. · 3.58 Impact Factor
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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 shinkei geka. Neurological surgery 09/2002; 30(8):829-36. · 0.13 Impact Factor
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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.
    Neuroscience Letters 09/2002; 328(1):25-8. · 2.06 Impact Factor
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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.
    Neurosurgical FOCUS 08/2002; 13(1):ECP2. · 2.14 Impact Factor
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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.
    Neurologia medico-chirurgica 08/2002; 42(7):297-300. · 0.65 Impact Factor
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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.
    Journal of Neuroscience Research 02/2002; 67(1):11-20. · 2.73 Impact Factor
  • Neurologia medico-chirurgica 01/2002; 42(7):297-300. · 0.65 Impact Factor
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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.
    Neuroscience Research 12/2001; 41(4):365-371. · 2.15 Impact Factor
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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.
    Endocrine Journal 05/2001; 48(2):233-9. · 2.02 Impact Factor
  • Endocrine Journal 01/2001; 48(2):133-139. · 2.02 Impact Factor
  • European Journal of Cancer 09/1999; 35. · 4.82 Impact Factor
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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 shinkei geka. Neurological surgery 03/1999; 27(2):133-8. · 0.13 Impact Factor
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    ABSTRACT: We studied changes in expression of F3/contactin (F3), a neuron-specific adhesion molecule, in the gerbil hippocampus after transient forebrain ischemia for 5 min. By immunohistochemical techniques using F3 antibody, we found a biphasic change in immunoreactivity for F3 in the CA1 area after ischemia. Western blotting of F3 protein showed a similar biphasic change. F3 immunoblots decreased to 67% of the control at 1 week, but then they increased and attained 159% at 3 weeks and 152% at 5 weeks after ischemia. Immunoreactivity of a neurofilament (NF145) showed a similar biphasic change to F3 but to a lesser extent. In contrast, microtubule-associated protein 2 (MAP2) immunoreactivity uniformly decreased after ischemia. In situ hybridization revealed that F3 messenger RNA (mRNA) hybridization signals in CA1 area were greatly reduced 1 week after ischemia, while the signals in the CA3 area were unchanged and even increased 3 weeks after ischemia. Damage to CA3 neurons by hyperthermic ischemia blocked the F3 increase in area CA1. Our results suggest that the initial decrease in F3 following ischemia reflects loss of CA1 neurons and the late increase in F3, which shows that a similar time course with neurofilaments may be caused by neurite sprouting.
    Experimental Brain Research 10/1998; 122(2):227-34. · 2.17 Impact Factor
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    ABSTRACT: Transient forebrain ischemia causes selective neuronal death in the hippocampal CA1 neurons. A short sublethal ischemic episode preceding ischemia of longer duration is known to increase tolerance against cell death. The mechanisms of this ischemic tolerance are still poorly understood. Here we show, using Ca2+ imaging, that intracellular calcium ([Ca2+]i) elevation in CA1 neurons after an anoxic-aglycemic episode is markedly inhibited in the ischemia-tolerant gerbil. The hippocampus of gerbils which did not acquire tolerance showed a high [Ca2+]i elevation during the anoxic-aglycemic episode, similar to controls. Since hypoxia/ischemia-induced neurodegeneration can be triggered by cytoplasmic Ca2+ overload, the tolerant gerbil may regulate calcium and keep [Ca2+]i below the critical level for initiating neuronal death.
    Neuroreport 07/1998; 9(8):1875-8. · 1.64 Impact Factor
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    ABSTRACT: Expression of the multidrug-resistance protein gene MRP, which confers non-P-glycoproteinmediated multidrug resistance, has been found in many drug-resistant variants and tumor samples. Recent studies have demonstrated that MRP functions as an ATP-dependent transporter functionally related to the previously described glutathione-conjugate (GS-X) pump. We have shown recently that the MRP and γ-glutamylcysteine synthetase (γ-GCS) heavy subunit mRNA levels are coordinately overexpressed in cisplatin (CP)-resistant human leukemia cells (Ishikawa et al., J Biol Chem 271: 14981–14988, 1996) and frequently co-elevated in human colorectal tumors (Kuo et al., Cancer Res 56: 3642–3644, 1996). In the present study, we showed the coexpression patterns of thirteen additional human drug-resistant cell lines representing different tumor cell origins selected with different agents, except for one doxorubicin-selected line which demonstrated minor elevation in MRP mRNA with no detectable increase in γ-GCS mRNA, suggesting that the increase of MRP mRNA preceded the increase in γ-GCS mRNA. Furthermore, in seventeen randomly selected untreated tumor cell lines, the overall correlation coefficient between MRP and γ-GCS mRNA levels was 0.861. In normal mice, the correlation coefficient of mrp and γ-gcs mRNA was 0.662 in fourteen tissues (kidney and liver were not included) analyzed. Kidney and liver expressed low levels of mrp relative to γ-gcs; however, these two tissues expressed high levels of a functionally related mrp homologue, mrp2 (cMoat or cMrp), which may have compensated for the underexpressed mrp in maintaining the total GS-X pump activities. Altogether, these results demonstrated the frequent coexpression of these two genes in various cell settings.
    Biochemical Pharmacology 03/1998; · 4.65 Impact Factor
  • Neuroscience Research - NEUROSCI RES. 01/1998; 31.
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    ABSTRACT: Treatment of human glioma A172 cells with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), an alkylating antitumor agent the primary target of which has been thought to be DNA, resulted in elevated expression of mRNA for multidrug resistance-associated protein (MRP) within the first 2 h and then a decrease in expression 24 h after the treatment. Western blot analyses revealed that levels of MRP in these ACNU-treated cells paralleled mRNA levels. Membrane vesicles prepared from ACNU-treated cells also displayed elevated transport activities for leukotriene C4, a known substrate for MRP. Gamma-glutamylcysteine synthetase (gamma-GCS) mRNA expression was coinduced with MRP by ACNU. Because gamma-GCS is the rate-limiting enzyme involved in the de novo biosynthesis of glutathione, increases in glutathione were also transiently induced by ACNU. These results demonstrate for the first time that the expression of functional MRP and gamma-GCS can be transiently coinduced by ACNU. Multiple short exposures (1 h) of ACNU following a long duration (1 week) of drug-free conditions resulted in the development of an ACNU-resistant population (designated A172R) that overexpressed MRP/gamma-GCS mRNA and had elevated transport activities for leukotriene C4. A172R exhibited cross-resistance to the antitumor drug doxorubicin and heavy metal sodium arsenate but not to cisplatin. Our results also demonstrate that intermittent treatments of human glioma cells with ACNU can lead to the development of MRP-related multidrug resistance. These results, taken together, reveal a possible new mechanism of the development of drug resistance for the antitumor nitrosoureas.
    Cancer Research 01/1998; 57(23):5292-9. · 9.28 Impact Factor

Publication Stats

979 Citations
236.29 Total Impact Points


  • 1983–2004
    • Jichi Medical University
      • • Department of Medicine
      • • Division of Neurology
      • • Division of Anatomy
      Totigi, Tochigi, Japan
  • 1996
    • University of Cambridge
      Cambridge, England, United Kingdom
  • 1984
    • Chiba University
      • Department of Biology
      Chiba-shi, Chiba-ken, Japan