Estimation of postmortem interval by changes in brain lipids : Application to estimate the time after brain death

为了估计死亡时间，研究了死后脑脂质的变化。对44例法医尸检病例的脑脂质进行了检查。测定总脂质、总磷脂和总游离脂肪酸，计算游离脂肪酸组成百分比。随着死后时间的延长，总游离脂肪酸占总脂肪的比例增加，而磷脂占总脂肪的比例下降。游离脂肪酸中16:0和18:0的比例较高，但前者随死后时间的延长有降低的趋势。比较了不同杀菌方式和贮藏温度对脂质变化的影响。采用氮窒息、斩首或腹腔注射戊巴比妥钠处死大鼠。在恒温箱中保持15、23、30的温度至120小时。游离脂肪酸中，18.0和20:4的组成随着时间的推移而减少，22.6的组成随着时间的推移而增加，但戊巴比比中毒死亡大鼠的总游离脂肪酸含量略低于氮窒息和断头死亡大鼠。两种杀伤方式对脂质变化的影响不显著，可能是由于其固有的非甾体期持续时间短。贮藏温度对脂质变化的影响较大，30℃贮藏温度对脂质变化的影响大于15、23℃贮藏温度。用戊巴比妥中毒法观察非性腺期持续时间对血脂变化的影响。戊巴比妥注射后斩首处死大鼠游离脂肪酸总量低于未注射戊巴比妥的斩首处死大鼠。戊巴比妥注射后15分钟和30分钟死亡大鼠体内总游离脂肪酸含量低于注射后5分钟死亡大鼠。我们打算研究脑脂质的变化，以估计脑死亡后的时间。

For the study of estimation of the time after death, postmortem changes in brain lipids were investigated. Brain lipids in 44 forensic autopsy cases were examined. Total lipids, total phospholipids and total free fatty acids were measured, and percentage of free fatty acid composition was calculated. Percentage of phospholipid to total lipid decreased, whereas that of total free fatty acids increased in accordance with postmortem interval. Percentages of 16 : 0 and 18 : 0 in the free fatty acid were high, although the former tended to decrease in accordance with postmortem interval.The influence of modes of killing and storage temperature on the changes of lipids was compared. Rats were killed by either nitrogen asphyxiation, decapitation, or intraperitoneal injection of sodium pentobarbital. The bodies were maintained at 15ﾟC,23ﾟC and 30ﾟC in incubator up to 120 hours. Among the free fatty acid, the composition of 18 : 0 and 20 : 4 decreased, whereas that of 22 : 6 increased with time, although the amounts of total free fatty acid of rats died of pentobarbital intoxication were somewhat lower than those of nitrogen asphyxiation and decapitation. The modes of killing did not significantly affect the changes of lipids presumably because of short duration of agonal stage inherent in them. The storage temperature of rat bodies influenced the changes of lipids, which were greater at 30ﾟC than at 15ﾟC and 23ﾟC.The influence of duration of agonal stage on the change of lipids was investigated by pentobarbital intoxication. The amounts of total free fatty acid of rats killed by decapitation after injection of pentobarbital were lower than those of rats killed by decapitation without pentobarbital injection. The amounts of total free fatty acid in rats died 15 or 30 minutes after pentobarbital injection were lower than those of 5 minutes.We intend to investigate the changes of brain lipids for estimation of the time after brain death.