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Biomedical subjects

Yuji Wada

Publications and source records attributed to Yuji Wada.

29 records · Page 2Linked to original sources
PubMed2002

Hypoxic tolerance induction in rat brain slices following 3-nitropropionic acid pretreatment as revealed by dynamic changes in glucose metabolism.

Pretreatment with 3-nitropropionic acid (3-NPA) has been shown to induce tolerance to ischemic/hypoxic brain damage. However, regional differences in tolerance induction by 3-NPA and the degree to which impaired glucose metabolism due to 3-NPA pretreatment itself is directly involved remain unknown. To evaluate these issues using dynamic positron autoradiography with [(18)F]2-fluoro-2-deoxy-D-glucose, the cerebral glucose metabolic rate (CMRglc) was serially measured before and after hypoxia-loading in rat brain slices pretreated with 3-NPA. CMRglc before hypoxia did not significantly differ between the 3-NPA pretreatment group and control group. The 3-NPA-associated recovery of CMRglc after reoxygenation was observed in the frontal cortex, hippocampus, and cerebellum, but not in the striatum and thalamus. Thus, we demonstrated the induction of region-specific hypoxic tolerance after 3-NPA pretreatment using CMRglc maintenance as an index of neuronal viability, and it is unlikely that this induction is associated with the persistence of impaired glucose metabolism due to 3-NPA pretreatment.

Animals↗
PubMed2002

EEG harmonic responses to photic stimulation in normal aging and Alzheimer's disease: differences in interhemispheric coherence.

OBJECTIVES: The distinction between electroencephalogram (EEG) driving responses in normal aging and Alzheimer's disease (AD) is unclear. This study was conducted to explore the structure of harmonic responses of EEG coherence during photic stimulation (PS) in AD. METHODS: EEG interhemispheric coherence was analyzed for each harmonic responses during PS (white flickers at 5, 10 and 15 flashes/sec) in younger subjects (20-25 years), non-demented elderly subjects (50-67 years) and AD patients (43-66 years). RESULTS: The elderly subjects had higher interhemispheric coherence during PS than the younger subjects, with significant differences found in the 6th (30Hz) and 8th (40Hz) harmonic responses to 5Hz PS. The AD patients had significantly smaller coherence than the elderly subjects in the 2nd (10Hz) and 4th (20Hz) harmonic responses to 5Hz PS, and in the fundamental (10Hz) and 2nd (20Hz) harmonic responses to 10Hz PS. These coherence values did not correlate with duration of the disease or with cognitive functioning as evaluated by MMSE score. CONCLUSIONS: A failure of stimulation-related brain activation in AD patients was observed in alpha-related frequencies, suggesting that AD is not the end result of normal aging of the brain, at least in terms of the mechanisms which are involved in PS-related functional organization.

Aged↗
PubMed2002

A case of diffuse neurofibrillary tangles with calcification.

We report a 79-year-old female with atypical senile dementia with Fahr-type calcification. The patient started to show memory disturbance at the age of 75 years, followed by visual hallucination, stereotypy, personality changes such as irritability, aggression and disinhibition. Brain computed tomography (CT) demonstrated bilateral and symmetric calcification of the basal ganglia and thalamus. Magnetic resonance imaging (MRI) revealed diffuse cortical atrophy pronounced in the fronto-temporal areas. On MRI T1-weighted images the calcified areas showed a mixture of low- and high-intensity signals. Based on the overlapping clinical symptoms of Alzheimer's disease and Pick's disease, together with the brain CT and MRI findings, we clinically diagnosed the patient as having 'diffuse neurofibrillary tangles with calcification' (DNTC). The characteristics of psychiatric symptoms and neuroradiological findings in DNTC are discussed.

Aged↗
PubMed2002

Interhemispheric differences of the correlation dimension in a human sleep electroencephalogram.

The interhemispheric differences of the correlation dimension (D2) in the sleep electroencephalogram (EEG) of eight healthy right-handed students was investigated. During slow wave sleep (SWS) the D2 of the central EEG and the temporal left hemisphere (LH) EEG were significantly higher than those in the right hemisphere (RH) EEG; but during rapid eye movement (REM) sleep, the D2 of the central EEG and the occipital RH EEG were significantly higher. The D2 of EEG in the left temporal site during REM sleep were significantly higher than in the right during the first and third sleep cycles, but these were significantly lower during the fourth and fifth sleep cycles. During REM sleep, temporal brain activity may shift from the LH to the RH as morning approaches.

Adult↗
PubMed2002

Effect of ethanol on human sleep EEG using correlation dimension analysis.

Our study was designed to investigate the influence of alcohol on sleep using the correlation dimension (D2) analysis. Polysomnography (PSG) was performed in 10 adult human males during a baseline night (BL-N) and an ethanol (0.8 g/kg body weight) night (Et-N). The mean D2 values during the Et-N and BL-N decreased significantly from wakefulness to stages 1, 2, and 3+4 of nonrapid eye movement (non-REM) sleep, and increased during REM sleep. The mean D2 of the sleep electroencephalogram (EEG) during stage 2 during the Et-N was significantly higher than during BL-N. In addition, the mean D2 values of the sleep EEG for the second, third and fourth sleep cycles during the Et-N were significantly higher than during the BL-N. These significant differences between BL-N and Et-N were not recognized by spectral and visual analyses. Our results suggest that D2 is a potentially useful parameter for quantitative analysis of the effect of ethanol on sleep EEGs throughout the entire night.

Adult↗
PubMed2002

Differences in EEG harmonic driving responses to photic stimulation between normal aging and Alzheimer's disease.

In order to investigate whether Alzheimer's disease (AD) is the end result of aging of the brain or the result of some other mechanism, we analyzed EEGs showing the absolute power of harmonic responses to photic stimulation (PS) in younger subjects, non-demented elderly subjects and AD patients. At rest, the AD patients generally showed less absolute power than the younger and elderly subjects, with significant differences found at 10 Hz and 20 Hz. Analysis of EEGs recorded during PS indicated that the elderly subjects generally demonstrated more absolute power than the younger subjects and AD patients. These findings suggest a failure of stimulation-related brain activation in AD patients, and provide further evidence that normal aging and AD employ different mechanisms for functional organization during PS.

Adult↗
PubMed2002

Fulminant subdural empyema treated with a wide decompressive craniectomy and continuous irrigation--case report.

A 56-year-old male presented with fulminant subdural empyema manifesting as rhinorrhea, periorbital cellulitis, fever, convulsions, and consciousness disturbance. Neuroimaging showed pansinusitis with skull destruction and extensive subdural empyema. Decompressive craniectomy, irrigation of the empyema, and subdural drainage were performed. Endoscopic sinus surgery was performed to remove the source of infection at the same time. Streptococcus milleri was cultured from the pus. Continuous irrigation of the subdural space with saline containing gentamicin for 7 days resulted in prompt elimination of pus and debris. The patient was discharged with only a slight neurological deficit.

Craniotomy↗