Kenichiro Sugita

Shizuoka Hospital, Sizuoka, Shizuoka, Japan

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Publications (139)289.94 Total impact

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    ABSTRACT: Isolated cerebral (basilar, posterior communicating and middle cerebral) arteries exist in a partially contracted state. To determine the Ca(2+)-buffering function of sarcoplasmic reticulum in the resting state of cerebral arteries, the effects of ryanodine that eliminates the function of sarcoplasmic reticulum, on tension and cellular Ca2+ level were compared in endothelium-denuded strips of the cerebral, coronary and mesenteric arteries of the dog. The addition of ryanodine to strips with basal tone caused a concentration-dependent contraction, which was significantly greater in the cerebral arteries than in the mesenteric or coronary artery. In the presence of 10(-5) M ryanodine, the caffeine (20 mM)-induced contraction was greatly attenuated in these arteries. After washout, the basal tone was greatly elevated in the cerebral arteries. The elevated tone was abolished by 10(-7) M nifedipine. The ryanodine-induced contractions were also abolished by 10(-7) M nifedipine. Nifedipine itself caused a relaxation from the basal tone in the cerebral arteries, suggesting the maintenance of myogenic tone. The basal Ca2+ influx in arteries measured after a 5-min incubation with 45Ca was significantly higher in the basilar artery than in the mesenteric artery. The basal Ca2+ influx was not increased by 10(-5) M ryanodine in either artery. The basal Ca2+ influx was decreased by 10(-7) M nifedipine in the basilar artery, but was unchanged in the mesenteric artery. These results suggest that: (1) the basal Ca2+ influx via L-type voltage-dependent Ca2+ channels was higher in the resting state of the cerebral arteries; (2) the greater part of the higher Ca2+ influx was buffered by Ca2+ uptake into the sarcoplasmic reticulum; and (3) therefore the functional elimination of sarcoplasmic reticulum by ryanodine caused a potent contraction in these arteries. Furthermore, the maintenance of myogenic tone in the cerebral arteries suggests that more Ca2+ enters the smooth muscle cell than the buffering ability of sarcoplasmic reticulum can handle.
    European Journal of Pharmacology 10/1996; 311(1):53-60. DOI:10.1016/0014-2999(96)00408-6 · 2.68 Impact Factor
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    ABSTRACT: The authors describe the use of a bifrontal basal interhemispheric approach with or without division of the anterior communicating artery (ACoA) for removal of large craniopharyngiomas. This approach is a more basal modification of the anterior interhemispheric approach; allowing preservation of most bridging veins. Since 1988, 22 patients underwent operations using this approach to achieve total or near-total excision of large craniopharyngiomas. Division of the ACoA was performed in 11 of 17 patients with retrochiasmatic tumors with no early or late complications related to division of the artery. There were no operative mortalities. Visual improvement (59%) and preservation of the pituitary stalk (64%) were achieved in a high percentage of patients. Preservation of the pituitary stalk correlated well with postoperative pituitary function. The bifrontal basal interhemispheric approach allowed a bilateral, wider operative field with better orientation and views of important neural structures and perforating arteries without requiring combination with other approaches. When the ACoA limited operative exposure, the artery could be divided safely. The authors discuss indications for, and advantages of, the bifrontal basal interhemispheric approach with or without division of the ACoA in the removal of large craniopharyngiomas.
    Journal of Neurosurgery 07/1996; 84(6):951-6. DOI:10.3171/jns.1996.84.6.0951 · 3.23 Impact Factor
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    ABSTRACT: Intracranial extracerebral cavernous angiomas (ECCAs) share the same histologic features as intracerebral lesions, but their clinical picture is different. Surgical treatment of ECCAs of the cavernous sinus remains a challenge for the neurosurgeon because of a high mortality and morbidity due to uncontrollable and massive hemorrhage. We have experienced seven patients with ECCAs of the cavernous sinus between 1982 and 1994. All cases were verified histologically during surgery and two were totally resected during the first surgical attempt. Six of seven patients were female. The mean age at diagnosis was 54.5 years (range; 43 to 71 years). Computed tomography showed a round or dumbbell-shaped mass in the area of the cavernous sinus. Magnetic resonance imaging revealed a low to isointense mass lesion on the T1-weighted image. Only one of our patients showed a minimal amount of vascular staining on angiography. The total excision of these malformations was difficult because intraoperative bleeding could be profuse. In one case, radiation therapy induced a reduction in the size of the tumor after failure of surgical removal. In planning surgical strategy for ECCAs, care should be taken to control the massive bleeding. Radiation therapy is helpful to suppress the tumor growth.
    Surgical Neurology 03/1996; 45(2):123-32. DOI:10.1016/0090-3019(95)00366-5 · 1.67 Impact Factor
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    ABSTRACT: A 32-year-old male presented with subarachnoid hemorrhage following head trauma. Initial carotid angiography revealed an aneurysm protruding from the dorsal wall of the supraclinoid internal carotid artery. Two weeks later, following two additional hemorrhagic episodes, repeat carotid angiography showed severe vasospasm and dramatic expansion of the aneurysm. He died 17 days after the accident. Autopsy and histological examination confirmed the diagnosis of a traumatic, false aneurysm of the internal carotid artery. Improved prognosis requires early recognition and surgical obliteration of such aneurysms.
    Neurologia medico-chirurgica 01/1996; 35(12):886-91. DOI:10.2176/nmc.35.886 · 0.65 Impact Factor
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    ABSTRACT: The coexistence of a symptomatic parasellar meningioma and an unruptured laterally projecting C3 carotid aneurysm in a 54 year old female is presented. Although the exact location of the aneurysm in relation to the distal doral ring could not be determined by preoperative neuroradiological studies, a surgical repair of the aneurysm was indicated since both the aneurysm and the meningioma could be exposed in the same operative field. All of the meningioma except for its dural attachment in the carotid cave was removed. Great care taken when drilling the anterior clinoid process as it had been croded by the aneurysm from below. The dural ring was tightly adherent to the neck of the aneurysm and had to be dissected sharply with a pair of microscissors. A prophylactic high flow EG-M2 radial arterial bypass graft was used to decrease the risk of stroke in this patient who had poor collateral circulation through the anterior and posterior communicating arteries. The aneurysm was clipped successfully and the patient was discharged without new neurological deficits. Surgical indications and operative technique are discussed.
    Journal of Clinical Neuroscience 10/1995; DOI:10.1016/0967-5868(95)90061-6 · 1.32 Impact Factor
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    ABSTRACT: The effect of human adrenomedullin on cerebral circulation was investigated in dogs in vivo and in vitro. Bolus administration of adrenomedullin or its homologous peptides, calcitonin gene-related peptide (CGRP) and amylin, into the vertebral artery induced a dose-dependent increase in vertebral blood flow. The potencies of adrenomedullin and CGRP were similar and approximately 100 times more than that of amylin. The effects of adrenomedullin and CGRP were inhibited by CGRP8-37, an antagonist of CGRP. In contrast to substance P, adrenomedullin did not induce an increase in blood flow after prior administration of CGRP. Pretreat-ment with either NG-nitro-L-arginine methyl ester or in-domethacin did not affect the adrenomedullin-induced increase in blood flow. Intracisternal administration of adrenomedullin induced dilation of the basilar and other major cerebral arteries in a dose-dependent manner, accompanied by an increase in the concentration of cyclic AMP in the cerebrospinal fluid. Adrenomedullin also induced relaxation of isolated basilar and middle cerebral arterial rings. These data suggest that adrenomedullin induces vasodilation of cerebral arteries and an increase in vertebral blood by acting at CGRP receptors positively coupled to adenylate cyclase, and that these effects are not dependent on nitric oxide or prostaglandin formation.Keywords: Adrenomedullin; Amylin; Angiography; Calcitonin gene-related peptide; Cyclic AMP; Vasodilation
    Journal of Cerebral Blood Flow & Metabolism 08/1995; 15(5):827-834. DOI:10.1038/jcbfm.1995.103 · 5.34 Impact Factor
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    ABSTRACT: Self-retaining retractors may be useful in spinal tumor surgery. In this study, the tumors were retracted away from the surrounding tissue by pronged hooks attached to flexible self-retaining retractors; by this process, we could avoid placing pressure on the spinal cord. A clear dissection plane was exposed between the underside of the tumor and the surrounding spinal cord, so that the surgeon had both hands free to perform the operation. Two retractor base systems were used: 1) Sugita's multipurpose headframe for the cervical region, and 2) a newly designed U-shaped, table-fixed retractor base for the thoracic and lumbosacral regions. Most retracting instruments used in cranial surgery can be used with either system.
    Neurosurgery 08/1995; 37(1):148-9; discussion 149-50. DOI:10.1097/00006123-199507000-00025 · 3.03 Impact Factor
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    ABSTRACT: In an attempt to clarify the characteristics of the pterional routes to the basilar bifurcation aneurysm, 65 consecutive surgical cases were retrospectively analyzed concerning the size of the aneurysm, the height of the aneurysm neck, the length of the clip blades, and the direction of clip application. Clipping was performed through the pterional route in 59 cases consisting of 14 opticocarotid and 45 retrocarotid routes. A subtemporal approach was performed for six low-positioned aneurysms. The opticocarotid approach was undertaken because of the following situations: 1) laterally protruded and/or highly sclerotic internal carotid artery (n = 8); 2) long, redundant A1 segment (n = 3); 3) an associated aneurysm of the internal carotid artery obstructing the retrocarotid space (n = 2); and 4) a short and/or large posterior communicating artery obstructing the retrocarotid space (n = 1). The range in height of the aneurysm neck was narrower in the opticocarotid approach (1-10 mm) than in the retrocarotid approach (-7-15 mm). The direction of clip application on the axial plane was more anteriorly deviated in the opticocarotid approach (41.4 +/- 12.8 degrees from the glabella-inion line) than in the retrocarotid approach (58.8 +/- 11.1 degrees; P = 0.01). The retrocarotid route (n = 45) was further subdivided into the medial or lateral retrocarotid routes, depending on the medial or lateral side to the posterior communicating artery, respectively. The medial retrocarotid approach (n = 9) made it possible to reach relatively high-positioned aneurysms (7.0 +/- 3.9 mm) compared with the lateral retrocarotid approach (4.2 +/- 4.7 mm; n = 29).(ABSTRACT TRUNCATED AT 250 WORDS)
    Neurosurgery 04/1995; 36(3):533-8; discussion 538-40. DOI:10.1227/00006123-199503000-00012 · 3.03 Impact Factor
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    ABSTRACT: Oligodendrocyte-type 2 astrocyte (O2A) progenitor cells in vivo might differentiate into oligodendrocytes. To examine the influence of the brain micro-environment on the differentiation, a bipotential glial cell line from the mouse cerebrum, designated OS3 cells, was implanted into the telencephalon of infant and adult mice. About a half of the OS3 cells injected into 1-week postnatal brain expressed galactocerebroside (GalC), and even myelin basic protein, which were not observed to be expressed in vitro. By contrast, in the brain over 6 months postnatally, many OS3 cells expressed glial fibrillary acidic protein, and did not express much GalC. These findings suggest that the differentiation of glial cells is controlled by stage specific factors in the brain.
    Neuroscience Letters 04/1995; 188(1):1-4. DOI:10.1016/0304-3940(95)11378-A · 2.06 Impact Factor
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    ABSTRACT: We investigated and compared the effects of pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) on cerebral circulation in anesthetized dogs. The intracisternal administration of PACAP-27, PACAP-38, and VIP dilated canine cerebral arteries in a dose-dependent manner. A 10 nmol dose of PACAP-27, PACAP-38, and VIP dilated the basilar artery by 23 +/- 3, 27 +/- 3 and 30 +/- 3%, respectively. Rostrally located arteries tended to be more responsive to PACAP-27. Pretreatment with NG-monomethyl-L-arginine did not affect PACAP-27-induced vasodilation. Vertebral artery blood flow was also affected by intra-arterial injection of these peptides in a dose-dependent manner. A 100 pmol dose of PACAP-27, PACAP-38, and VIP increased the vertebral artery blood flow by 42 +/- 10, 29 +/- 4, and 62 +/- 11%, respectively. The VIP receptor antagonist, [Lys1,Pro2,5,Arg3,4,Tyr6]VIP, inhibited both the VIP- and PACAP-38-induced increase in vertebral artery blood flow. These findings suggest that PACAP plays a role in the regulation of cerebral circulation.
    European Journal of Pharmacology 04/1995; 275(3):259-66. DOI:10.1016/0014-2999(95)00011-9 · 2.68 Impact Factor
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    ABSTRACT: To evaluate the effects of unroofing the optic canal during retraction of the optic nerve, the authors monitored changes in visual evoked potentials (VEPs) stimulated by a light-emitting diode in the canine model. At rest, an early VEP wave was reliably observed with an amplitude of 8.2 +/- 0.6 microV and a latency of 51.5 +/- 0.7 msec; this wave was named N50. The intracranial optic nerve was retracted using a weight of 5, 10 or 50 g. The earliest change in VEP noted during retraction was a reduction in N50 wave amplitude. The length of time required until N50 amplitude decreased to 50% of the control group (T50) was 10.7 +/- 1.8 minutes with a weight of 5 g, 4.9 +/- 0.7 minutes with 10 g, and 2.9 +/- 0.4 minutes with 50 g, with statistically significant differences between the groups. Retraction of the optic nerve with all weights finally resulted in the disappearance of the N50 wave. The amplitude of the N50 wave recovered fully to control size when retraction was released immediately after the wave disappeared. The time course of amplitude recovery did not differ significantly between groups. Unroofing the optic canal prolonged the T50 during retraction significantly to 20.7 +/- 2.9 minutes with a weight of 5 g, 18.9 +/- 4.2 with 10 g, and 9.0 +/- 2.4 with 50 g. These results demonstrate that unroofing the optic canal can protect the optic nerve from damage during operations that require optic nerve retraction.
    Journal of Neurosurgery 03/1995; 82(2):284-7. DOI:10.3171/jns.1995.82.2.0284 · 3.23 Impact Factor
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    ABSTRACT: Regional differences in the role of nitric oxide in cerebral vasomotor control were investigated with a nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine, or a precursor of nitric oxide, L-arginine using both dog cerebral angiography for the larger artery study and rat isolated arterioles for the microcirculation study. NG-monomethyl-L-arginine (10 mumol) constricted the dog cerebral arteries, by 15.6%, 17.5%, and 27.3% in the middle cerebral, anterior cerebral, and basilar arteries, respectively. The greater constriction of the basilar artery did not reach statistical significance. However, L-arginine (100 mumol) produced significantly greater dilation of basilar arteries than the middle cerebral or anterior cerebral (31.3% vs. 16.7% or 13.1%). NG-monomethyl-L-arginine at 10(-3) M constricted rat arterioles originating from basilar arteries significantly more than the middle cerebral arteries (23% vs. 14%). L-arginine at 10(-3) M dilated rat arterioles from basilar arteries significantly more than from the middle cerebral artery (24 vs. 11%). These findings suggest that the roles of nitric oxide in vasomotor control differs by region in the brain, and it may be greater in vessels of the posterior than of the anterior circulation.
    Brain Research Bulletin 02/1995; 38(4):365-9. DOI:10.1016/0361-9230(95)02001-8 · 2.97 Impact Factor
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    ABSTRACT: This study was undertaken to determine the effects of oxyhemoglobin on vasopressin-induced responses in cerebral arterioles. Rat intracerebral arterioles about 60 microns in diameter were isolated and cannulated using pipettes. Changes in diameter secondary to the extraluminal application of drugs were monitored through a video micro-scaler. Vasopressin produced a triphasic, dose-dependent response consisting of vasodilation (10(-11) M), vasoconstriction (10(-9)-10(-8) M) and a decrease in vasoconstriction (10(-7)-10(-6) M). Pretreatment with oxyhemoglobin (10(-5) M) abolished the vasodilation induced by the lower dose vasopressin and doubled the vasoconstriction induced by the higher dose. The combination of L-arginine (10(-4) M) and superoxide dismutase (600 U) restored low-dose vasopressin vasodilation and suppressed high-dose vasoconstriction in oxyhemoglobin-pretreated arterioles, while they showed little effect when used singly. This study indicates that oxyhemoglobin enhances vasopressin-induced constriction of intracerebral arterioles and these effects can be inhibited by the combination of L-arginine and superoxide dismutase.
    Life Sciences 02/1995; 56(5):PL123-7. DOI:10.1016/0024-3205(94)00964-3 · 2.30 Impact Factor
  • Neurologia medico-chirurgica 01/1995; 35(10):719-722. DOI:10.2176/nmc.35.719 · 0.65 Impact Factor
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    ABSTRACT: Lymphokine-activated killer (LAK) cells generated from peripheral blood lymphocytes incubated with recombinant interleukin-2 were transfected with the human γ-interferon (HuIFN-γ) gene by means of liposomes having a positive charge on their surface. The cells secreted significant amounts of HuIFN-γ (reaching more than 5 U/ml) into the culture medium. The HuIFN-γ produced by the cells induced intercellular adhesion molecule-1 (ICAM-1) and enhanced the expression of Fas antigen on the surface of human glioma cells. Also, LAK cells transfected with HuIFN-γ gene exhibited reinforcement of cytotoxicity toward human glioma cell lines (U251-MG and SK-MG-1). Furthermore, the reinforcement was significantly quenched by anti-ICAM-1 and/or anti-TNF-α monoclonal antibody.
    Cancer Science 01/1995; 86(1):95-100. DOI:10.1111/j.1349-7006.1995.tb02993.x · 3.53 Impact Factor
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    ABSTRACT: We raised an anti-glioma monoclonal antibody, named G-22, that specifically recognizes a human glioma-associated surface antigen. Proven to be useful for target imaging of malignant gliomas after radioisotope labeling and cerebrospinal fluid diagnosis by enzyme-linked immunospecific assay, G-22 was found to immunoprecipitate an 85-kDa glycoprotein of the human glioma U-251MG cell. We purified this antigen by G-22-coupled cyanogenbromide-activated Sepharose affinity chromatography, and sequence analysis demonstrated that the 54 amino acid residues were identical to positions 55-108 of human CD44. The results show that the smallest spliced form (85 kDa) of CD44 is strongly expressed in glioma cells.
    Cancer Immunology and Immunotherapy 12/1994; 39(5):313-7. DOI:10.1007/BF01519984 · 3.94 Impact Factor
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    ABSTRACT: We report a case with giant aneurysm of the right vertebral artery in which remission of essential hypertension occurred following surgical decompression. The patient presented with a history of progressive gait disturbance and essential hypertension over a period of 4 years and 10 years respectively. Computerised tomography scan demonstrated a giant thrombosed aneurysm in the right vertebral artery. The aneurysm was trapped and decompressed to reduce the neurological deficits. Post-operatively, the gait disturbance recovered with complete remission of the long standing essential hypertension.
    Journal of Clinical Neuroscience 10/1994; 1(4):277-9. DOI:10.1016/0967-5868(94)90070-1 · 1.32 Impact Factor
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    ABSTRACT: Vasopressin may regulate the regional cerebral blood flow (rCBF) via two balancing effects: increased flow from the vessels dilated by nitric oxide from the endothelium, and decreased flow from the vessels contracted by direct stimulation of smooth muscle. The effect on the rCBF in anesthetized dogs following the intracisternal or intraarterial administration of vasopressin was investigated by laser flowmetry with the device placed on the dura over the parietal cortex. The intracisternal injection of 1 nmol vasopressin significantly increased the rCBF to 145.3 +/- 27.3% of base line. In contrast, the intravertebral arterial injection of vasopressin had no significant effect on the rCBF. This can be explained by a difference in the affected vasculature; mainly large vessels in the subarachnoid space vs. whole vascular system supplied by the vertebral artery. The intracisternal injection of 10 mumol of NG-monomethyl-L-arginine (L-NMMA) reduced the rCBF; pretreatment with this agent significantly suppressed the elevation in rCBF induced by vasopressin. The intraarterial injection of L-NMMA reduced the rCBF more than its intracisternal administration. It also suppressed the rCBF induced by vasopressin.
    Journal of the Autonomic Nervous System 10/1994; 49 Suppl:S133-6. DOI:10.1016/0165-1838(94)90101-5
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    ABSTRACT: The present study was undertaken to determine the role of nitric oxide (NO) in the regulation of vasomotor tone in rat cerebral parenchymal arterioles under physiological and pathological conditions. Cerebral arterioles, about 60 microns in diameter, were isolated from rats and cannulated with glass pipettes. Changes in the arteriolar diameter secondary to extraluminal application of drugs were monitored continuously through a videodimension analysis system. The arterioles were dilated by L-arginine (12.2 +/- 2.2% at 10(-3) M) and were constricted by NG-monomethyl-L-arginine (L-NMMA) (13.8 +/- 1.5% at 10(-4) M) in a dose-dependent manner. Pretreatment with superoxide dismutase (600 U) increased sensitivity to L-arginine. These results suggest that NO plays an important role in regulation of basal vasomotor tone of cerebral parenchymal arterioles under physiological conditions. Next, NO-modification of vasomotor responses to an endogenous vasoactive substance, arginine vasopressin (AVP) was studied in cerebral parenchymal arterioles. Increasing concentrations of AVP produced biphasic responses of vasodilation (10(-11) M) and vasoconstriction (10(-10)-10(-8) M). Inhibition of NO by pretreatment with L-NMMA (10(-4) M) or oxyhemoglobin (10(-5) M) abolished the vasodilation and enhanced the vasoconstriction by AVP. Therefore, under pathological conditions in which NO function was suppressed, such endogenous substances may produce contraction in parenchymal arterioles instead of dilation with aggravation of cerebral ischemia.
    Journal of the Autonomic Nervous System 10/1994; 49 Suppl:S63-6. DOI:10.1016/0165-1838(94)90089-2
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    ABSTRACT: The function of nitric oxide in spastic cerebral arteries after subarachnoid hemorrhage (SAH) was angiographically investigated in dogs. On days 4 and 7, after two intracisternal injections of autologous blood, higher concentrations of L-arginine than those of endogenous L-arginine in the cerebrospinal fluid produced a transient vasodilation of the spastic basilar artery, whereas NG-monomethyl-L-arginine (L-NMMA) produced no significant vasoconstriction. The vasodilator effect of L-arginine after SAH was stronger on day 4 than day 7, but less than that in intact dogs. Vasopressin, which is known to activate the endothelial L-arginine pathway, could induce a vasodilation only after the treatment with L-arginine. Intracisternal injection of superoxide dismutase (SOD), which caused no effect by itself, enhanced the duration of the vasodilator effect of L-arginine on the basilar artery on day 4 and both the magnitude and duration of that effect on day 7. Thus, the basal release of nitric oxide was impaired after SAH, but the ability to synthesize nitric oxide in the vascular wall was not abolished. Enhancement of L-arginine's effect by SOD suggested that the inactivation of nitric oxide by superoxide anion contributed to the development of vasospasm.
    Journal of the Autonomic Nervous System 10/1994; 49 Suppl:S83-7. DOI:10.1016/0165-1838(94)90093-0

Publication Stats

2k Citations
289.94 Total Impact Points

Institutions

  • 1996
    • Shizuoka Hospital
      Sizuoka, Shizuoka, Japan
  • 1991–1995
    • Nagoya University
      • Division of Neurosurgery
      Nagoya-shi, Aichi-ken, Japan
  • 1983–1994
    • Shinshu University
      • • Department of Neurosurgery
      • • Department of Medicine
      Shonai, Nagano, Japan
  • 1993
    • Nagoya City University
      • Department of Pharmacology
      Nagoya, Aichi, Japan
    • Sanjay Gandhi Post Graduate Institute of Medical Sciences
      • Department of Neurosurgery
      Lucknow, Uttar Pradesh, India