Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Kazuo Kitazawa is active.

Publication


Featured researches published by Kazuo Kitazawa.


Neurological Research | 2001

Inflammatory cytokine cascade released by leukocytes in cerebrospinal fluid after subarachnoid hemorrhage.

Takeomi Takizawa; Tsuyoshi Tada; Kazuo Kitazawa; Yuichiro Tanaka; Kazuhiro Hongo; Mitsuaki Kameko; Kei-ichi Uemura

Abstract Subarachnoid hemorrhage (SAH) elicits an inflammatory response in the subarachnoid space, which is mediated by the release of various cytokines. To assess their involvement in post-hemorrhagic complications, we determined the source and time-course of the release of inflammatory cytokines and acute-phase proteins in cerebrospinal fluid (CSF) following SAH. Concentrations of interleukin (IL)-1β, IL-6, transforming growth factor-β1 (TGF-β1) and C-reactive protein (CRP) in CSF of 36 patients with SAH were measured by enzyme-linked immunoabsorbent assay (ELISA). Floating cells collected from the CSF were centrifuged four to six days after SAH, and examined immunohistochemically. Intracellular IL-1β and IL-6 were examined by flow cytometric analysis. The molecular weight of TGF-β1 in CSF of 30 patients was examined by Western blot analysis. The TGF-β1 levels of patients who had undergone ventriculoperitoneal (VP) shunt (n = 19) was significantly higher than nonshunt group (n = 16). The CRP levels of VP shunt group was significantly higher than nonshunt group. IL-6 concentration was maximal within day 0-1 and it was secreted by neutrophils and monocytes. ELISA showed consistently low levels of IL-1β, whereas a proportion of monocytes and lymphcytes were IL-1β-positive by flow cytometric analysis. TGF-β1 levels were also maximal on day 0-1 according to ELISA, although it tended to be in the inactive form derived from platelets. A 25 kDa band of TGF-1 was detectable for at least 13 days after SAH, which may have been secreted in part by neutrophils and monocytes. CRP levels in CSF peaked on day 2-3. The present results suggest that leukocytes induced by SAH play an important role in post-hemorrhagic inflammation in the subarachnoid space by releasing IL-6 and TGF-β1. The CRP and TGF-β1 levels in CSF are strongly concerned with communicating hydrocephalus after SAH. [Neurol Res 2001; 23: 724-730]


Stroke | 1994

Elevation of transforming growth factor-beta 1 level in cerebrospinal fluid of patients with communicating hydrocephalus after subarachnoid hemorrhage.

Kazuo Kitazawa; Tsuyoshi Tada

Background and Purpose Transforming growth factor‐&bgr;1 (TGF‐&bgr;1) is a multifunctional polypeptide that controls the production of extracellular matrix protein. Platelets store a large quantity of TGF‐&bgr;1, which is released at hemorrhage. We recently reported that human recombinant TGF‐&bgr;1 induced communicating hydrocephalus in mice. The aim of this study was to determine whether TGF‐&bgr;1 is related to the development of communicating hydrocephalus after subarachnoid hemorrhage (SAH). Methods TGF‐&bgr;1 in the cerebrospinal fluid of 24 patients with SAH was measured with enzyme‐linked immunosorbent assay. The levels were compared between hydrocephalic and nonhydrocephalic groups. Western blot analysis was performed to determine active TGF‐&bgr;1 in the cerebrospinal fluid. Results TGF‐&bgr;1 rapidly decreased from the onset of SAH. The level of TGF‐&bgr;1 of 13 patients showing ventricular dilatation with periventricular low density on computed tomographic scan was 1.07±0.37 ng/mL on days 12 through 14, which was significantly higher than 0.52±0.21 ng/mL in patients without ventricular dilatation (P<.02). Furthermore, the TGF‐&bgr;1 level of patients who had undergone ventriculoperitoneal shunt (n=11) was 1.11±0.09 ng/mL on days 12 through 14, which was also higher than the level of the nonshunt group (n=13) (0.56±0.22 ng/mL; P<.01). A 25‐kD band was demonstrated by Western blot analysis in the cerebrospinal fluid of a patient with SAH. Conclusions Our results strongly suggest that TGF‐&bgr;1 plays an important role in generating communicating hydrocephalus after SAH. (Stroke. 1994;25:1400‐1404.)


Acta Neurochirurgica | 2001

Results of Direct Surgery for Aneurysmal Subarachnoid Haemorrhage: Outcome of 2055 Patients who Underwent Direct Aneurysm Surgery and Profile of Ruptured Intracranial Aneurysms

Michihiko Osawa; Kazuhiro Hongo; Yuichiro Tanaka; Y. Nakamura; Kazuo Kitazawa; Kobayashi S

Summary Background and Purpose. The purpose of this study is to evaluate the therapeutic value of our surgical treatment of subarachnoid haemorrhage in a large series with standardized surgical principles. Methods. Results of 2055 direct operations on ruptured intracranial aneurysms, treated in our institutions, where surgical indications, instruments and techniques were standardized, between 1988 and 1998, were retrospectively evaluated and outcome of the patients was discussed; cases treated by intravascular procedures were excluded. Results. According to the evaluation at discharge, 1083 (52.7%) patients were excellent, 324 (15.8%) good and 223 (10.9%) fair. There were 160 (7.8%) patients of poor outcome and the remaining 265 (12.9%) died. There were no differences in the outcome between pre-operative Hunt & Kosnik grade I and II, Fisher Scale 1 and 2, anterior circulation aneurysms and posterior circulation aneurysms except those at and around the basilar bifurcation, men and women, and those clipped and not clipped. Conclusions. The factors related to poor outcomes were, age of 60 years or over, pre-operative Hunt & Kosnik grade II or more, Fisher Scale 3 or more, aneurysm size over 15 mm in diameter, and location at and around the basilar artery bifurcation. The results presented in this study show the status of our direct surgical management of subarachnoid haemorrhage in a large series with standardized surgical principles and procedures.


Childs Nervous System | 1995

Infantile subdural fluid collection: diagnosis and postoperative course

Nobuhito Morota; Keizo Sakamoto; Norio Kobayashi; Kazuo Kitazawa; Shigeaki Kobayashi

The authors reviewed 47 cases of infantile subdural fluid collection with regard to diagnosis and postoperative course after placement of a subdural-peritoneal shunt. CT scan with contrast enhancement proved to be an important diagnostic modality, showing vessels in the subarachnoid space as high-density spots. Utilizing this technique, we were able to differentiate the following varieties of fluid collection: (1) subdural fluid collection, in which enhancing vessels were seen on the brain surfae, (2) subarachnoid fluid collection, in which vessels were on the inner table of the cranium, and (3) coexistence of subdural and subarachnoid fluid collections, in which vessels were between the inner table of the cranium and the brain surface. The postoperative course of subdural fluid collection was characterized as follows: (1) the subdural fluid collection decreased first, with increased subarachnoid fluid collection; (2) the subarachnoid fluid collection remained after the disappearance of subdural fluid collection; and (3) the brain expanded again later. Subdural fluid collection disappeared about 1 month after the shunt operation, which could lead occlusion of the shunt system. Postoperative enlargement of the subarachnoid space was an early indicator of the efficacy of the subduralperitoneal shunt.


Journal of Clinical Neuroscience | 2001

Specific characteristics and management strategies of posterior cerebral artery aneurysms:report of eleven cases

Kazuo Kitazawa; Yuichiro Tanaka; Shinsuke Muraoka; Tsuyoshi Tada; Hiroshi Okudera; Yasser Orz; Kazuhiko Kyoshima; Shigeaki Kobayashi

Owing to the deep location of the posterior cerebral artery (PCA) and its close relationship with the brainstem and surrounding vital structures, surgical treatment of aneurysms in this region is complex. This study was undertaken in an attempt to better delineate the surgical risks of PCA aneurysms. A retrospective analysis was undertaken in 11 patients with PCA aneurysm surgically treated between 1988 and 1996 at Shinshu University and its affiliated hospitals. Data regarding surgical strategy, surgical complications and outcomes were analysed. Seven aneurysms were saccular (including one mycotic) and the other four were fusiform, dissecting, thrombosed and an infundibular dilatation. The locations of the aneurysms were at the P1 segment in two patients, P1-P2 junction in two, P2 segment in six and P3 segment in one. Six saccular non-mycotic aneurysms were treated with neck clipping and the other five aneurysms were treated each with proximal occlusion of the parent artery, excision of the aneurysm or wrapping. All aneurysms were satisfactorily exposed except one large saccular aneurysm. Surgical outcomes were either good recovery or moderate disability in 10 patients, and severe disability in one patient with a large aneurysm due to temporal lobe contusion. In conclusion it is the responsibility of the surgeon dealing with rare PCA aneurysms to be aware of these specific characteristics and to appreciate which surgical technique is appropriate for each patient.


Journal of Clinical Neuroscience | 2005

Postoperative vasospasm of unruptured paraclinoid carotid aneurysms: analysis of 30 cases

Kazuo Kitazawa; Kazuhiro Hongo; Yuichiro Tanaka; Susumu Oikawa; Kazuhiko Kyoshima; Shigeaki Kobayashi

This study was conducted to determine the incidence, severity, and causes of delayed vasospasm after clipping of unruptured paraclinoid aneurysms of the internal carotid artery (ICA). A retrospective analysis was made of 30 patients, who underwent clipping of unruptured paraclinoid aneurysms in our institution between 1991 and 1998. We compared angiograms before and after operation and classified them into two groups: vasospasm group and non-vasospasm group. Eleven variables were assessed as to their relationship to delayed vasospasm. There were 9 patients (30%) in the vasospasm group, of which 3 patients (10%) were clinically symptomatic. For all symptomatic patients, aggressive treatment, including triple-H therapy, was conducted with good outcome. The number of clips used (p<0.04) and temporary occlusion of the ICA (p<0.005) were statistically significant factors associated with the incidence of vasospasm. It is suggested that mechanical stimulation to the vascular wall of the ICA is responsible for causing spasm in addition to intraoperative bleeding around the dural ring.


Neurosurgery | 1998

Color Doppler Ultrasound Imaging in the Emergency Management of an Intracerebral Hematoma Caused by Cerebral Arteriovenous Malformations: Technical Case Report

Kazuo Kitazawa; Junpei Nitta; Hiroshi Okudera; Shigeaki Kobayashi

OBJECTIVE AND IMPORTANCE Ruptured arteriovenous malformations (AVMs) are important causes of spontaneous intracerebral hemorrhages. This is a report of emergency hematoma removal, avoiding damage to the nidus of the AVM, using intraoperative color Doppler imaging. CLINICAL PRESENTATION A 38-year-old woman suddenly presented with coma. The patient underwent emergency surgery immediately after admission, without preoperative angiographic examination, because of progressive neurological deterioration caused by a massive hematoma in the right basal ganglia, as diagnosed with computed tomographic scanning. INTERVENTION A right frontotemporoparietal craniotomy was performed. Intraoperative ultrasound imaging with a color Doppler system (EUP-NS32, 5 MHz; Hitachi Medical, Tokyo, Japan) clearly demonstrated a nidus complex in the hematoma. Based on the imaging, effective decompression of the hematoma was performed without damage to the AVM complex. CONCLUSION Color Doppler imaging (with real-time availability) of an atypical hematoma provided significant information on the vascular lesion causing the hematoma and could reduce the surgical risks during emergency evacuation of large intracerebral hemorrhages resulting from ruptured AVMs.


Journal of Clinical Neuroscience | 2007

Subtle computed tomography abnormalities in cerebral deep sinus thrombosis.

Tomomi Iwashita; Kazuo Kitazawa; Jun-ichi Koyama; Hisashi Nagashima; Toru Koyama; Yuichiro Tanaka; Kazuhiro Hongo; Hiroshi Okudera; Kazufumi Okamoto

A patient with cerebral deep sinus thrombosis, which was not diagnosed on the first examination, is reported. A 46-year-old woman presented with headache and vomiting. Neurological examination and a brain computed tomography (CT) scan showed no obvious abnormal findings. The patient suffered disturbed consciousness on the day after the examination, and was admitted to our emergency centre. A CT scan and magnetic resonance imaging revealed an ischaemic lesion in the left basal ganglia, suggesting deep sinus occlusion. Anticoagulant therapy was administered. One day after admission, a CT scan showed a haematoma and severe brain swelling in the same region. Cerebral angiography demonstrated a straight sinus occlusion. Intracranial pressure was not controlled with hypothermia, and the patient died 25 days after admission. Review of the initial CT scan revealed subtle, early findings of deep venous thrombosis that were missed on first examination.


Stereotactic and Functional Neurosurgery | 2010

Pallidotomy for Severe Tardive Jaw-Opening Dystonia

Takao Hashimoto; Kosuke Naito; Kazuo Kitazawa; Sugio Imai; Tetsuya Goto

Bilateral pallidotomy was performed in a schizophrenic patient with severe jaw-opening dystonia developed after chronic neuroleptic treatment. The dystonia led to sustained mandibular joint dislocation, and tracheotomy was performed after suffocation. The jaw-opening dystonia disappeared immediately following pallidotomy; the tracheotomy was closed, and he regained eating and speech ability. Analysis of the neuronal firing of the globus pallidus revealed low neuronal firing rates in the internal pallidum (GPi) and an irregular burst pattern of the GPi cells compared to those in Parkinson’s disease. These results suggest that pallidotomy is a treatment option for tardive jaw-opening dystonia and that dystonia of this type is driven by abnormal neural activities in the GPi.


Journal of Stroke & Cerebrovascular Diseases | 2016

Clinico-Radiological Characteristics and Pathological Diagnosis of Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage

Tadashi Doden; Hiromasa Sato; Etsuko Sasahara; Takahiro Murata; Takehiro Yako; Kazuo Kitazawa; Kayoko Higuchi; Shigeaki Kobayashi; Takao Hashimoto

OBJECTIVE We aim to clarify the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage and to investigate the efficacy of pathological diagnosis using biopsy specimens. METHOD We retrospectively reviewed 253 consecutive patients with cortico-subcortical hemorrhage who had been admitted to Aizawa Hospital between January 2006 and July 2013. We had performed craniotomy and hematoma evacuation in 48 patients, as well as biopsy of the evacuated hematoma, cerebral parenchyma adjacent to the hematoma, or both, and they were classified according to the histological results (positive or negative for vascular amyloid deposition) and to the Boston criteria. We compared the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage. We also investigated the detection rate of cerebral amyloid angiopathy with respect to the origins of the specimens. RESULTS Pathological examination revealed that 22 subjects were positive for vascular amyloid. The number of the cerebral microbleeds located in the deep or infratentorial region was significantly larger in the negative group than in the positive group (P <.05). There was no significant difference in the distribution of lobar cerebral microbleeds and in the prevalence of hypertension. In the probable cerebral amyloid angiopathy-related intracerebral hemorrhage patients, the probability of having vascular amyloid detected by biopsy of both hematoma and parenchyma was 100%. Rebleeding in the postoperative periods was observed in 2 cases (9.1%) of the positive group. CONCLUSIONS Our results demonstrate the importance and safety of biopsy simultaneously performed with hematoma evacuation. Deep or infratentorial microbleeds are less correlated with cerebral amyloid angiopathy-related intracerebral hemorrhage than with noncerebral amyloid angiopathy-related intracerebral hemorrhage.

Collaboration


Dive into the Kazuo Kitazawa's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge