Yoshinori Ozawa

Hypermetabolic state following experimental head injury

AbstractLocal cerebral glucose utilization (LCGU) was studied in 35 conscious rats after a fluid percussion injury (cerebral contusion). The experiments were divided into two parts.(I)Natural course: LCGU was quantitatively measured in 17 rats by the14C-deoxyglucose autoradiographic method (Sokoloff et al. 1977) at 1, 2, 4 and 24 hours after injury. Sham operation was made in six rats.(II)DC-potential and LCGU: LCGU was studied with DC-potential and EEG monitoring in 12 rats. Results were as follows: (I) i) Glucose uptake was reduced at the center of the contusion in all cases. ii) Two different effects were observed in LCGU change two hours after injury: normal or slight increase in four of six rats (type A) and a remarkable increase in the cortex of the injured hemisphere in two of six rats (type B). iii) The pattern of increase in LCGU (type B) resembles that of cortical spreading depression.(II) i) Negative shift of DC-potential concomitant with EEG suppression in the injured hemisphere was observed frequently one to two hours after injury. ii) The increased LCGU pattern during DC-potential negative shift was identical with that of type B. iii) LCGU pattern without DC-potential change resembles that of type A.We concluded that the hypermetabolism occurring in the damaged cortex was due to a spreading depression. The findings obtained here should yield very important information concerning pathogenesis and treatment of human head injury.

Use of an IC Recorder as a voice output memory aid for patients with prospective memory impairment

This study evaluated the use of an IC Recorder as a voice output memory aid for patients with prospective memory impairment. The IC Recorder can output about 300 previously recorded messages at programmed times. The spoken messages prompted various daily tasks for eight patients with acquired memory impairments. One of these tasks, such as diary writing, or a letter-writing exercise was selected for each patient as a main task, and its completion was logged. These completion data demonstrated that the messages output by the IC Recorder were highly effective in prompting the main tasks for five of the eight patients. This study suggests that the IC Recorder has great potential as a voice output memory aid to assist patients with prospective memory impairment.

Changes of local cerebral glucose utilization, DC potential and extracellular potassium concentration in experimental head injury of varying severity

SummaryThe negative shift of DC potential was associated with an increase of extracellular potassium and energy metabolism. Therefore this dramatic phenomenon following the trauma to the brain was thought to be identical to spreading depression.1.Spreading depression was most frequently observed between one and two hours after injury.2.Spreading depression can be elicited in the deep structures as well as in the cortex. The more severe the injury, the more frequently the negative shifts were observed. The DC index seems to correlate well with the severity of the experimental model. It is concluded that the energy metabolism after the brain contusion was different from structure to structure and was changing continuously in the course of time.