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Dive into the research topics where Atsushi Mizuma is active.

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Featured researches published by Atsushi Mizuma.


Journal of Stroke & Cerebrovascular Diseases | 2013

Phase I Study of Intravenous Low-dose Granulocyte Colony-stimulating Factor in Acute and Subacute Ischemic Stroke

Yusuke Moriya; Atsushi Mizuma; Tsuyoshi Uesugi; Yoichi Ohnuki; Eiichiro Nagata; Wakoh Takahashi; Hiroyuki Kobayashi; Hiroshi Kawada; Kiyoshi Ando; Shigeharu Takagi; Shunya Takizawa

BACKGROUND Granulocyte colony-stimulating factor (G-CSF; filgrastim) may be useful for the treatment of acute ischemic stroke because of its neuroprotective and neurogenesis-promoting properties, but an excessive increase of neutrophils may lead to brain injury. We examined the safety and tolerability of low-dose G-CSF and investigated the effectiveness of G-CSF given intravenously in the acute phase (at 24 hours) or subacute phase (at 7 days) of ischemic stroke. METHODS Three intravenous dose regimens (150, 300, or 450 μg/body/day, divided into 2 doses for 5 days) of G-CSF were examined in 18 patients with magnetic resonance imaging (MRI)-confirmed infarct in the territory of the middle cerebral artery. Nine patients received the first dose at 24 hours poststroke (acute group) and 9 patients received the first dose on day 7 poststroke (subacute group; n = 3 at each dose in each group). A scheduled administration of G-CSF was skipped if the patients leukocyte count exceeded 40,000/μL. Patients received neurologic and MRI examinations. RESULTS We found neither serious adverse event, drug-related platelet reduction nor splenomegaly. Leukocyte levels remained below 40,000/μL at 150 and 300 μg G-CSF/body/day, but rose above 40,000/μL at 450 μg G-CSF/body/day. Neurologic function improvement between baseline and day 90 was more marked after treatment in the acute phase versus the subacute phase (Barthel index 49.4 ± 28.1 v 15.0 ± 22.0; P < .01). CONCLUSIONS Low-dose G-CSF (150 and 300 μg/body/day) was safe and well tolerated in ischemic stroke patients, and leukocyte levels remained below 40,000/μL.


Journal of Medical Microbiology | 2012

A case of scrub typhus with acalculous cholecystitis, aseptic meningitis and mononeuritis multiplex.

Kayoko Hayakawa; Masayuki Oki; Yusuke Moriya; Atsushi Mizuma; Yoichi Ohnuki; Hidetaka Yanagi; Ryuki Fukuda; Hideki Ozawa; Shunya Takizawa; Atsushi Takagi

We present an unusual case of a patient with scrub typhus who developed acalculous cholecystitis, aseptic meningitis and mononeuritis multiplex. The patient was successfully treated with oral minocycline. To our knowledge, this is the first report of mononeuritis multiplex caused by scrub typhus.


Journal of Stroke & Cerebrovascular Diseases | 2016

Phase II Trial of Intravenous Low-Dose Granulocyte Colony-Stimulating Factor in Acute Ischemic Stroke

Atsushi Mizuma; Toru Yamashita; Syoichiro Kono; Taira Nakayama; Yasuhiko Baba; Shinji Itoh; Kunihiko Asakura; Yoshiki Niimi; Takashi Asahi; Kazuya Kanemaru; Tatsuro Mutoh; Satoshi Kuroda; Hiroyuki Kinouchi; Koji Abe; Shunya Takizawa

BACKGROUND Granulocyte colony-stimulating factor (G-CSF) has shown neuroprotective and neurogenerative activities in experimental studies, and our previous phase I clinical study suggested the safety and potential efficacy of low-dose G-CSF in acute ischemic stroke patients. The present phase II trial is aimed to evaluate the effect of G-CSF administration on neurological function and infarct volume, compared with a placebo group. METHODS Forty-nine acute ischemic stroke patients (29 males, 20 females; 71 ± 10 years) within 24 hours after onset were recruited. Eligible patients were randomized 2:2:1 to receive G-CSF 150 µg/body/day, G-CSF 300 µg/body/day, and placebo, respectively. We evaluated clinical outcome in terms of the National Institutes of Health Stroke Scale, the modified Rankin Scale, and the Barthel Index at 90 days after onset, together with changes in infarct volume on magnetic resonance imaging. RESULTS We found no serious adverse event, including change in leukocyte levels, which remained below 31,000/µL, at 150 and 300 µg G-CSF/body/day. Clinical outcome scores did not show any significant difference among the 3 groups. Chronological changes in infarct volume also showed no significant difference. CONCLUSIONS G-CSF was well-tolerated at 150 and 300 µg/body/day in patients with acute ischemic stroke. However, administration of G-CSF at both 150 and 300 µg/body/day neither contributed to functional recovery nor reduced infarct volume at 3 months after onset, compared with the control group. The apparent lack of effectiveness may have been due to the small sample size. A trial of combination therapy with recombinant tissue plasminogen activator and G-CSF is planned.


Internal Medicine | 2017

Adult-onset Mitochondrial Myopathy, Encephalopathy, Lactic Acidosis, and Stroke (MELAS)-like Encephalopathy Diagnosed Based on the Complete Sequencing of Mitochondrial DNA Extracted from Biopsied Muscle without any Myopathic Changes

Masako Mukai; Eiichiro Nagata; Atsushi Mizuma; Mitsuhiko Yamano; Keizo Sugaya; Ichizo Nishino; Yu-ichi Goto; Shunya Takizawa

The clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) are not uniform. We herein report a male patient with unusual MELAS-like encephalopathy who had been experiencing isolated recurrent stroke-like episodes since he was 33 years old without any particular family history. Despite an extensive investigation, he had no other signs suggestive of MELAS. Although the muscle pathology showed a normal appearance, a mitochondrial genome sequence analysis of the biopsied muscle revealed a heteroplasmic m.10158T>C mutation in the mitochondrial complex I subunit gene, MT-ND3. To prevented further deterioration of the higher brain function, the early diagnosis and treatment of mitochondrial stroke-like episodes is important.


Heart Lung and Circulation | 2014

Relationship between atherosclerotic risk factors and aortic plaques in patients with first-ever ischaemic stroke.

Atsushi Mizuma; Chikage Kijima; Kazuyuki Iijima; Yoshiaki Goto; Kazunari Honma; Takashi Yasuda; Kentaro Tokuoka; Yasuhisa Kitagawa; Shunya Takizawa

OBJECTIVE Aortic plaque is considered a risk factor of ischaemic stroke, and both ulceration and plaque thickness are considered important. However, the relative importance of aortic plaque and carotid plaque remains unclear. The purpose of this study is to clarify the relation between aortic and carotid plaque lesions and atherosclerotic risk factors in patients with acute ischaemic stroke. METHODS We enrolled 76 patients with first-ever ischaemic stroke, undergoing transoesophageal echocardiography, whose aetiology of ischaemic stroke was unknown. We divided the patients into two groups according to aortic plaque thickness, based on previous reports, i.e., a high-risk group (over 4mm) and a low-risk group (less than 4mm). We also examined several atherosclerotic risk factors. RESULTS Mean age, gender and hypertension was not significantly different between the low-risk and high-risk group. HDL-cholesterol (P<0.01), LDL/HDL ratio (P<0.05), non-HDL-cholesterol (P<0.05), HbA1c (P<0.05) and eGFR (P<0.01) were significantly different between the two groups. Max plaque thickness in the carotid artery was correlated with aortic plaque lesions. CONCLUSION Multiple atherosclerotic risk factors are associated with greater aortic plaque lesions. Aortic plaque is important not only as an embolic source, but also as one of the atherosclerotic markers.


Internal Medicine | 2017

Paraneoplastic anti-3-hydroxy-3-methylglutary-coenzyme a reductase antibody-positive immune-mediated necrotizing myopathy in a patient with uterine cancer

Atsushi Mizuma; Maiko Kouchi; Shizuka Netsu; Sachiko Yutani; Ruriko Kitao; Shigeaki Suzuki; Ken-ya Murata; Eiichiro Nagata; Shunya Takizawa

We report the case of a 69-year-old woman with proximal limb muscle weakness, who received post-operative chemotherapy for uterine cancer. Her serum creatinine kinase level was high (10,779 mg/dL) and a muscle biopsy from her left biceps revealed various sizes of muscle fibers accompanied by necrotic and regenerating fibers. She was positive for anti-3 hydroxy-3-methylglutary-coenzyme A reductase (anti-HMGCR) antibodies, but negative for anti-signal recognition particle (anti-SRP) antibodies. She was diagnosed with immune-mediated necrotizing myopathy (IMNM) and treated with prednisolone. Our findings indicate that not only drug-induced myopathy but also paraneoplastic myopathy can be involved in the pathogenesis of IMNM.


Case Reports in Oncology | 2016

A Case of Suspected Breast Cancer Metastasis to Brachial Plexus Detected by Magnetic Resonance Neurography

Atsushi Mizuma; Chikage Kijima; Eiichiro Nagata; Shunya Takizawa

Metastasis of breast cancer is often detected through a long-term course and difficult to diagnose. We report a case of brachial plexopathy suspected to be the initial lesion of breast cancer metastasis, which was only detected by magnetic resonance (MR) neurography. A 61-year-old woman was admitted to our hospital within 2 years after operation for breast cancer because of progressive dysesthesia and motor weakness initially in the upper limb on the affected side and subsequently on the contralateral side. Enhanced computed tomography, axillary lymph node echo, gallium scintigraphy, and short tau inversion recovery MR images showed no abnormalities. MR neurography revealed a swollen region in the left brachial plexus. We suspected neuralgic amyotrophy and initiated treatment with intravenous immunoglobulin therapy and steroid therapy. However, there was no improvement, and the progression of motor weakness in the bilateral lower limbs appeared over 4 years. Concomitant elevation of carbohydrate antigen 15-3 level (58.9 U/ml) led us to suspect breast cancer metastasis, which was associated with the worsening of neurological findings, although gallium scintigraphy and bone scintigraphy showed no inflammatory and metastatic lesions. Swelling of the cauda equina in enhanced lumbar MR imaging and abnormal accumulation at the brachial plexus and cervical spinal cord in positron-emission tomography were newly detected contrary to the normal findings on the gallium scintigraphy, which suggested cerebrospinal fluid seeding. We suspected breast cancer metastasis about the initial brachial plexopathy based on the clinical course. MR neurography may be a helpful tool to detect metastatic lesion, especially in nerve roots.


Neurological Research | 2014

Dynamic cross-sectional changes of the middle cerebral artery in atherosclerotic stenosis detected by 3·0-Tesla MRI

Atsushi Mizuma; Tatsuya Ishikawa; Nao Kajihara; Hayato Takano; Kazuyuki Endo; Mami Kawakata; Syuhei Shibukawa; Tomoya Nakamura; Hiroaki Nishio; Noriharu Yanagimachi; Shunya Takizawa

Abstract Objectives: Atherosclerotic stenosis of the middle cerebral artery (MCA) is one of the causes of ischemic stroke, but aside from investigations using magnetic resonance angiography (MRA), studies evaluating stenosis are rare. The purpose of this study was to assess dynamic changes of MCA cross section between the systolic and diastolic phases in patients with cerebral infarction using 3·0-Tesla magnetic resonance imaging (3T MRI). Methods: We assessed 12 stroke patients with M1 stenosis in the MCA and 12 healthy volunteers. We measured MCA cross sections (proximal/distal to stenosis and on the stenosis) in the systolic and diastolic phases by synchronizing imaging with heartbeats, as well as the maximum flow velocity by using cine-phase contrast (PC) MRI. Each patient also underwent conventional MRA. Results: Differences in cross sections between systolic and diastolic phases were significantly smaller in the stenosed artery compared to the distal (P < 0·05) and proximal areas (P < 0·01) in stroke patients. The difference in maximal blood velocity between systolic and diastolic phases at the M1 stenosis was significantly larger than that in the area proximal to the stenosis (P < 0·05). Discussion: We clearly demonstrated dynamic cross-sectional changes in the stenotic areas by 3T MRI, suggesting hemodynamic shear stress, which may further enhance MCA atherosclerosis.


Case reports in rheumatology | 2014

A Case of Polyarteritis Nodosa Associated with Cytomegalovirus Infection

Maiko Kouchi; Shinji Sato; Masahiro Kamono; Akiko Taoda; Kazuyuki Iijima; Atsushi Mizuma; Ruriko Kitao; Masatoshi Mihara; Hideki Ozawa; Tadayuki Ishihara; Atsushi Takagi; Yasuo Suzuki

A 77-year-old man suffering from prolonged fever of unknown origin and bilateral leg edema was referred to our hospital. On physical examination, he had fever, general fatigue, bilateral lower leg edema, and muscle weakness of the right upper extremity and left lower extremity. Neurological examination indicated motor and sensory disturbance. Electromyography revealed mononeuritis multiplex and myopathy. A biopsy of the left biceps muscle indicated necrotizing vasculitis with fibrinoid necrosis. Considering all the data together, he was diagnosed as having polyarteritis nodosa (PAN) and concurrent active cytomegalovirus (CMV) infection. His symptoms improved promptly on treatment with 50 mg of prednisolone. This case emphasizes the importance of CMV infection as one of possible etiologies of PAN and reports a therapeutic strategy for this syndrome.


Journal of Stroke & Cerebrovascular Diseases | 2013

Cerebral Microbleeds on T2*-Weighted Images and Hemorrhagic Transformation after Antithrombotic Therapies for Ischemic Stroke

Wakoh Takahashi; Yusuke Moriya; Atsushi Mizuma; Tsuyoshi Uesugi; Yoichi Ohnuki; Shunya Takizawa

To assess the predictive value of cerebral microbleeds (CMBs) on gradient-echo T2*-weighted magnetic resonance imaging for hemorrhagic transformation (HT) after antithrombotic therapy for an acute ischemic stroke, we prospectively examined the relationship between CMBs on T2*-weighted images before the start of therapy and the appearance of HT in a series of patients treated with antithrombotic therapies. The subjects were consecutive acute ischemic stroke patients admitted to Tokai University Hospital (187 subjects, mean age±SD: 74±11 years). The prevalence of CMBs was not significantly different between the subjects with and without HT on computed tomography (CT) (19% versus 36%, P=.081). In both the subgroup of patients treated with anticoagulants and the subgroup treated with antiplatelets, the prevalence of HT was not significantly different between the subjects with and without CMBs (anticoagulants, 9% versus 21%, P=.161; antiplatelets, 0% versus 9%, P=.542). The odds ratios (ORs) of increasing the National Institutes of Health Stroke Scale score (1.14, 95% confidence interval [CI]: 1.04-1.26, P=.005) and decreasing the Alberta Stroke Program Early CT Score on diffusion-weighted images (ASPECTS-DWI) (1.32, 95% CI: 1.10-1.59, P=.003) were significantly increased for the appearance of HT, but the OR of CMBs (.35, 95% CI: .09-1.41, P=.140) was not significantly increased for the appearance of HT. In conclusion, the severity of neurological deficits and the ASPECTS-DWI are closely correlated to the development of HT related to anticoagulants/antiplatelets but not to CMBs on T2*-weighted images.

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