| Co-Investigator(Kenkyū-buntansha) |
IKEMATSU Kazuya Nagasaki University, Graduate School of Biochemical Science, Lecture, 大学院・医歯薬学総合研究科, 講師 (80332857)
TSUDA Ryouichi Nagasaki University, Graduate School of Biochemical Science, Lecture, 大学院・医歯薬学総合研究科, 講師 (20098875)
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| Research Abstract |
The oxygen regulated protein 150-kDa (ORP-150) is only induced in hypoxic conditions. We performed an immunohistochemical and morphometrical study on the expression of ORP-150 in the brains of sudden infant death (SID) victims. The cerebral cortexes of 18 infants were used for this study. Each tissue section was incubated with anti-ORP-150 polyclonal antibodies and the number of ORP-150 positive cells was counted. In the cluster analysis, the 18 cases were classified into three groups (A-C groups). Group A was composed of 6 sudden infant death syndrome (SIDS) cases and its mean value of ORP-150 positive cells was 66.75+/-3.44, Group B (6 severe respiratory infectious disease such as pneumonia and bronchitis including sepsis) : 39.50+/-2.52 and Group C (5 SIDS and 1 severe respiratory infectious disease) 16.00+/-2.92, respectively. These results might reflect chronic hypoxic condition before death, because ORP-150 is only induced when a hypoxic condition exist, but not acute hypoxia. An
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d chronic hypoxic state is likely to be antecedent to SIDS. Therefore, immunohistochemical analysis of OPR-150 in the brain of SID cases may be very useful to differentiate between SIDS and acute asphyxia. Moreover, we examined the expression of ORP-150 in the adult samples, and discussed its significance in forensic practice. The cerebral cortexes of 31 cases (asphyxia 9 cases, hypothermia : 4, exsanguinations 5, CO intoxication (CO) : 6, sudden cardiac death (SCD): 7) were used for this study. The same immunohistolical method was used. In the multiple linear regression method, the estimated regression coefficient of ORP-150 on age was significant (p0.039), thus, we could find that the ORP-150 expression level depended on age. Using analysis of covariance, we compared the means of ORP-150, LS1VIEAN, which means hypothetic average value excluding influence of age, for each cause of death. The LSMEAN +/-S.E. was 84.74+/-9.03 in hypothermia, 57.52+/-6.34 in asphyxia, 46.68+/-6.70 in CO, 24.84+/-8.05 in exsanguinations, and 16.24+/-7.35 in SCD. As a result of the analysis, the LSMEAN of the ORP-150 expression level was related to the cause of death. There might be differences in the duration of brain ischemia before death. For example, SCD is presumed to be instant death, while brain ischemia continues for several minutes in asphyxia, CO and exsanguinations, and for several hours in hypothermia cases. Therefore, the immunohistochemical and morphometrical analysis of ORP-150 in the brain may be very useful to determine the duration of brain ischemia before death in forensic autopsy cases. Less
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