Estimation of the postmortem duration of mouse tissue by electron spin resonance spectroscopy.

Shinobu Ito,Tomohisa Mori,Toshiko Sawaguchi,Hideko Kanazawa

doi:10.1155/2011/973172

Abstract

Electron spin resonance (ESR) method is a simple method for detecting various free radicals simultaneously and directly. However, ESR spin trap method is unsuited to analyze weak ESR signals in organs because of water-induced dielectric loss (WIDL). To minimize WIDL occurring in biotissues and to improve detection sensitivity to free radicals in tissues, ESR cuvette was modified and used with 5,5-dimethtyl-1-pyrroline N-oxide (DMPO). The tissue samples were mouse brain, hart, lung, liver, kidney, pancreas, muscle, skin, and whole blood, where various ESR spin adduct signals including DMPO-ascorbyl radical (AsA∗), DMPO-superoxide anion radical (OOH), and DMPO-hydrogen radical (H) signal were detected. Postmortem changes in DMPO-AsA∗ and DMPO-OOH were observed in various tissues of mouse. The signal peak of spin adduct was monitored until the 205th day postmortem. DMPO-AsA∗ in liver (y = 113.8–40.7 log (day), R1 = −0.779, R2 = 0.6, P < .001) was found to linearly decrease with the logarithm of postmortem duration days. Therefore, DMPO-AsA∗ signal may be suitable for detecting an oxidation stress tracer from tissue in comparison with other spin adduct signal on ESR spin trap method.

Highlights

Electron spin resonance (ESR) or electron paramagnetic resonance (EPR) is widely used to analyze free radical species in living body and materials
The hfcc of dimethtyl-1-pyrroline N-oxide (DMPO)-OOH, DMPO-Ascorbic acid (AsA)∗, and DMPO-H was in agreement to three digits after decimal point within the max range of ±0.0009, and this value was almost the same as the previous study [20]
Further tests for identification showed that the peak of DMPOOH was decayed with the addition of AsA solution, while the peak of DMPO-OOH was decayed with the addition of Superoxide dismutase (SOD) solution

Summary

Introduction

Electron spin resonance (ESR) or electron paramagnetic resonance (EPR) is widely used to analyze free radical species in living body and materials. Fujita et al [7] showed that (1) ESR signals from bloodstains are effective in estimating the age of human and (2) ESR signals regularly change over time within the period of 432 days In these ESR studies, measurements were performed at low temperature (140◦K) for detecting the ESR signal of protein-bonded ions. ESR is widely used to analyze living body and material in forensic medicine, and it can be potentially used to estimate the age of human from bloodstains. In those cases, ESR measurements were performed at room temperature unless otherwise mentioned.

Methods

Results

Conclusion