Ken Nagata | Research Institute for Brain and Blood Vessels (original) (raw)
Papers by Ken Nagata
Sleep and Biological Rhythms, 2007
Japanese Psychological Research, Mar 1, 2000
Brain Topography, 1993
Since Matsuoka and associates (1978) first applied topographic mapping of EEG power data to the f... more Since Matsuoka and associates (1978) first applied topographic mapping of EEG power data to the functional evaluation of effects of drug in patients with brain tumors, topographic quantitative analysis of the EEG has been thought to be useful in the estimation of the cerebral dysfunction responsible for given scalp potentials in the clinical settings, although there are still controversies concerning various aspects of the data acquisition, statistical application, spatial resolution, and its limitation in clinical use (Rodin 1991; Welch 1992). The localization and lateralization of the EEG abnormalities which can be estimated more easily on the topographic quantitative EEG mapping have been one of the main interest in the clinical applications in patients with such neurological disorders as cerebrovascular disease and dementias (Nuwer et al. 1987; Jackel et al. 1987). This article focused on localization in topographic quantitative EEG mapping in comparison with positron emission tomography (PET) and clinical symptomatology in patients with discrete brain lesions.
Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control, 1995
Nihon rinsho. Japanese journal of clinical medicine, 2011
Cognitive Brain Research, 2001
Nihon Naika Gakkai Zasshi, 2011
Stroke, 2010
Background and Purpose— A prospective, multicenter, observational cohort study was conducted to c... more Background and Purpose— A prospective, multicenter, observational cohort study was conducted to clarify the association between major bleeding events and blood pressure (BP) levels during follow-up before development of bleeding events in antithrombotic users. Methods— A total of 4009 patients taking oral antithrombotic agents for cardiovascular or cerebrovascular diseases (2728 men, 69±10 years old) were followed. Changes in systolic and diastolic BPs between entry and the last clinic visit before intracranial hemorrhage (ICH) or extracranial hemorrhage were assessed. Results— Over a median follow-up of 19 months, ICH developed in 31 patients and extracranial hemorrhage developed in 77. Entry BP levels were similar among patients with ICH, those with extracranial hemorrhage, and those without hemorrhagic events. Both systolic BP and diastolic BP were relatively high during follow-up as compared with the levels at entry in patients with ICH, whereas they showed plateaus in patients ...
Stroke, 2008
Background and Purpose— We sought to determine the incidence and severity of bleeding events in p... more Background and Purpose— We sought to determine the incidence and severity of bleeding events in patients with stroke and cardiovascular diseases who were taking oral antithrombotic agents in Japan, where the incidence of hemorrhagic stroke is higher than in Western countries. Methods— A prospective, multicenter, observational study was conducted; 4009 patients who were taking oral antithrombotic agents for stroke and cardiovascular diseases were enrolled. The patients were classified into 4 groups according to their antithrombotic treatment: the single antiplatelet agent group (47.2%); the dual antiplatelet agent group (8.7%); the warfarin group (32.4%); and the warfarin plus antiplatelet agent group (11.7%). The primary end point was life-threatening or major bleeding according to the MATCH trial definition. Results— During a median follow-up of 19 months, there were 57 life-threatening and 51 major bleeding events, including 31 intracranial hemorrhages. The annual incidence of the...
Sleep and Biological Rhythms, 2007
Neurobiology of Aging, 2000
Journal of the Neurological Sciences, 2008
The inflammation plays a critical role in the stroke onset and even in the worsening of the lesio... more The inflammation plays a critical role in the stroke onset and even in the worsening of the lesions. Therefore, the investigation of inflammatory response in the acute stage may contribute to improve the treatment of ischemic stroke. High-sensitive CRP (hsCRP), IL-6 and TNFalpha were measured as inflammatory markers on admission and in the 28th day after the onset. Oxidized LDL was measured simultaneously, since it can be a marker of reactive oxygen species which reflect the activity of inflammation. Ischemic stroke patients within 24 h after the onset (n=105) were included in this study. All patients were classified into cardioembolism, large-artery atherosclerosis, lacunar infarction, branch atheromatous disease and arterial dissection groups based on the findings of MRI and MRA and clinical records. Oxidized LDL was significantly increased in the acute phase of all cases. The amplified level of IL-6 was related to the worse outcome. The increase of TNFalpha in lacunar infarction was statistically correlated to the neurological severity on admission. In conclusion, IL-6 may predict not only the severity of the stroke lesions but also the outcome of patients. TNFalpha may suggest the small arterial lesions.
Journal of the Neurological Sciences, 1997
Journal of Neurosurgery, 2009
Object The authors analyzed cerebral perfusion and metabolism in patients with internal carotid a... more Object The authors analyzed cerebral perfusion and metabolism in patients with internal carotid artery stenosis before and after carotid artery stenting (CAS). Methods Sixteen patients with internal carotid artery stenosis (> 70%) underwent PET scanning before CAS, 1–7 days after CAS, and 3–4 months after CAS to assess a variety of parameters related to cerebral perfusion and metabolism. Results Cerebral blood flow at rest (CBFrest) significantly increased in the immediate postoperative stage before returning to normal levels over the long term; this trend was also recognized on the contralateral side. In contrast, there was gradual improvement in the rate of CBF variation on acetazolamide administration (% CBFaz). Cerebral perfusion pressure (CBF/cerebral blood volume) increased rapidly during the acute stage and decreased in the long term, and the oxygen extraction fraction decreased slightly during the acute stage before normalizing over the long term. The cerebral metabolic r...
Journal of Neurology, 1989
Sleep and Biological Rhythms, 2007
Japanese Psychological Research, Mar 1, 2000
Brain Topography, 1993
Since Matsuoka and associates (1978) first applied topographic mapping of EEG power data to the f... more Since Matsuoka and associates (1978) first applied topographic mapping of EEG power data to the functional evaluation of effects of drug in patients with brain tumors, topographic quantitative analysis of the EEG has been thought to be useful in the estimation of the cerebral dysfunction responsible for given scalp potentials in the clinical settings, although there are still controversies concerning various aspects of the data acquisition, statistical application, spatial resolution, and its limitation in clinical use (Rodin 1991; Welch 1992). The localization and lateralization of the EEG abnormalities which can be estimated more easily on the topographic quantitative EEG mapping have been one of the main interest in the clinical applications in patients with such neurological disorders as cerebrovascular disease and dementias (Nuwer et al. 1987; Jackel et al. 1987). This article focused on localization in topographic quantitative EEG mapping in comparison with positron emission tomography (PET) and clinical symptomatology in patients with discrete brain lesions.
Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control, 1995
Nihon rinsho. Japanese journal of clinical medicine, 2011
Cognitive Brain Research, 2001
Nihon Naika Gakkai Zasshi, 2011
Stroke, 2010
Background and Purpose— A prospective, multicenter, observational cohort study was conducted to c... more Background and Purpose— A prospective, multicenter, observational cohort study was conducted to clarify the association between major bleeding events and blood pressure (BP) levels during follow-up before development of bleeding events in antithrombotic users. Methods— A total of 4009 patients taking oral antithrombotic agents for cardiovascular or cerebrovascular diseases (2728 men, 69±10 years old) were followed. Changes in systolic and diastolic BPs between entry and the last clinic visit before intracranial hemorrhage (ICH) or extracranial hemorrhage were assessed. Results— Over a median follow-up of 19 months, ICH developed in 31 patients and extracranial hemorrhage developed in 77. Entry BP levels were similar among patients with ICH, those with extracranial hemorrhage, and those without hemorrhagic events. Both systolic BP and diastolic BP were relatively high during follow-up as compared with the levels at entry in patients with ICH, whereas they showed plateaus in patients ...
Stroke, 2008
Background and Purpose— We sought to determine the incidence and severity of bleeding events in p... more Background and Purpose— We sought to determine the incidence and severity of bleeding events in patients with stroke and cardiovascular diseases who were taking oral antithrombotic agents in Japan, where the incidence of hemorrhagic stroke is higher than in Western countries. Methods— A prospective, multicenter, observational study was conducted; 4009 patients who were taking oral antithrombotic agents for stroke and cardiovascular diseases were enrolled. The patients were classified into 4 groups according to their antithrombotic treatment: the single antiplatelet agent group (47.2%); the dual antiplatelet agent group (8.7%); the warfarin group (32.4%); and the warfarin plus antiplatelet agent group (11.7%). The primary end point was life-threatening or major bleeding according to the MATCH trial definition. Results— During a median follow-up of 19 months, there were 57 life-threatening and 51 major bleeding events, including 31 intracranial hemorrhages. The annual incidence of the...
Sleep and Biological Rhythms, 2007
Neurobiology of Aging, 2000
Journal of the Neurological Sciences, 2008
The inflammation plays a critical role in the stroke onset and even in the worsening of the lesio... more The inflammation plays a critical role in the stroke onset and even in the worsening of the lesions. Therefore, the investigation of inflammatory response in the acute stage may contribute to improve the treatment of ischemic stroke. High-sensitive CRP (hsCRP), IL-6 and TNFalpha were measured as inflammatory markers on admission and in the 28th day after the onset. Oxidized LDL was measured simultaneously, since it can be a marker of reactive oxygen species which reflect the activity of inflammation. Ischemic stroke patients within 24 h after the onset (n=105) were included in this study. All patients were classified into cardioembolism, large-artery atherosclerosis, lacunar infarction, branch atheromatous disease and arterial dissection groups based on the findings of MRI and MRA and clinical records. Oxidized LDL was significantly increased in the acute phase of all cases. The amplified level of IL-6 was related to the worse outcome. The increase of TNFalpha in lacunar infarction was statistically correlated to the neurological severity on admission. In conclusion, IL-6 may predict not only the severity of the stroke lesions but also the outcome of patients. TNFalpha may suggest the small arterial lesions.
Journal of the Neurological Sciences, 1997
Journal of Neurosurgery, 2009
Object The authors analyzed cerebral perfusion and metabolism in patients with internal carotid a... more Object The authors analyzed cerebral perfusion and metabolism in patients with internal carotid artery stenosis before and after carotid artery stenting (CAS). Methods Sixteen patients with internal carotid artery stenosis (> 70%) underwent PET scanning before CAS, 1–7 days after CAS, and 3–4 months after CAS to assess a variety of parameters related to cerebral perfusion and metabolism. Results Cerebral blood flow at rest (CBFrest) significantly increased in the immediate postoperative stage before returning to normal levels over the long term; this trend was also recognized on the contralateral side. In contrast, there was gradual improvement in the rate of CBF variation on acetazolamide administration (% CBFaz). Cerebral perfusion pressure (CBF/cerebral blood volume) increased rapidly during the acute stage and decreased in the long term, and the oxygen extraction fraction decreased slightly during the acute stage before normalizing over the long term. The cerebral metabolic r...
Journal of Neurology, 1989