Rapid Detection of Irreversible Acetylcholineasterase Inhibitor by Mass Spectrometry Assay

Here we developed a rapid method to detect acetylcholinesterase （ACHE） activity by matrix-assisted laser de- sorption/ionization Fourier transform mass spectrometry （MALDI-FTMS） for screening irreversible AChE inhibi- tors. Due to its good salt-tolerance and low sample consumption, MALDI-FTMS could facilitate rapid detection, especially detection in real application. AChE activity was determined through calculating abundance of substrate and product in mass spectrometry. By this approach, we investigated the relation of organophosphorous （OP） con- centrations and AChE inhibition. Shown in different inhibition curves from different OP pesticides, enzyme inhibi- tions still kept good correlation with concentration of OPs. Finally, this AChE-inhibited method was applied to screen whole bloods of four decedents and discuss their death reason. In contrast to healthy persons, three of dece- dents showed low AChE activity, and probably died for irreversible AChE inhibitors. Through the following de- tecting in GC-MS/MS, the possible death reason of these three decedents was confirmed, and another decedent actually died for sumicidin, a non-AChE inhibitor. It demonstrated that screening irreversible AChE inhibitors by detecting enzyme activity in MALDI-FTMS provided fast and accurate analysis results and excluded another toxicants not functioning on ACHE. This method offered alternative choices for indicating the existence of enzyme inhibitors.

Astrocytic clasmatodendrosis in the cerebral cortex of methamphetamine abusers

Postmortem investigation of methamphetamine(MA)abuse is an important task in forensic pathology.The present study investigated morphological changes in the astrocytes in the parietal cerebral cortex of MA abusers.Glial fibrillary acidic protein immunoreactivity in the cerebral cortex was examined in forensic autopsy cases for MA-detected group and control group.Clasmatodendrotic astrocytes(including those with swollen cell bodies and disintegrating distal processes)were frequently observed in the cerebral cortex of MA abusers.Quantitative analysis using a colour image processor showed a concomitant increase in the astrocyte area and astrocyte-to-vessel area ratio(size and number of astrocytes)in the grey matter in acute MA fatality and other MA-involved cases,although the astrocyte area(size)was also increased in cases of asphyxiation.The total astrocyte area(size)in the white matter was significantly higher in MA fatalities and asphyxia than in the other groups involving MA abusers.Those indices were independent of blood MA level,age,sex,survival or postmortem time.These observations suggest the increasing number and hypertrophic changes of astrocytes in the grey matter in MA abusers can be the outcome of long-term abuse,while disintegrating distal processes may exist only in acute fatal MA intoxication.