Using nuclear magnetic resonance (NMR) analyze the metabolite changes after death

Using nuclear magnetic resonance (NMR) analysis of metabolite changes after death, the time of death can provide accurate and reliable information.

Forensic on the importance of self-evident, provided the scientific evidence for convicted or not guilty judgment, is important.Available evidence including fingerprint identification, DNA analysis, blood morphological analysis (BPA), the time of death, and after the death of time interval (PMI).

PMI interval is most commonly used in the above evidence, so it is considered to be one of the most important data.Determine the PMI method has the following several kinds: according to the physical change in the body (including temperature, degree of muscle stiffness and death spot);DNA degradation;Forensic entomology;As well as carbon dating.Within a few hours after death, can be obtained through the analysis of the physical change of the body to accurate calculation results of the PMI.In the presence of a few weeks to a few years after the death of, the other method is more accurate.For a few hours to a few weeks after the death of this period of time, so far has not been any a kind of method, PMI data can provide accurate and reliable.

Metabonomics in PMI inference, has unlimited potential

At present, metabonomics showing the unlimited potential, can be in a few hours to a few weeks after the death of this period of time, to infer the PMI.Organisms can be analyzed the technology system of all components, can be monitored for changes after the death of metabolites in body fluids.Ideally, these metabolites should change with the relatively long time after death, linear.In this way can obtain accurate and reliable data.Therefore, the current study is, in the highly fit with the above conditions to find the most potential metabolites in the body fluids.

Many preliminary study in a series of body fluids, determine the metabolic changes, but the recent work on animal models, suggests the eyedrops that aqueous humor (AH) and vitreous body fluids (VH), is the most suitable for PMI of body fluids.Compared with other such as blood, body fluids, from solution to learn the point of view, is isolated from the eye drops are separate.So its metabolite changes slowly, which makes the measurement more reliable.

Recently, some from Novosibirsk, Russia's international center of ct scan and the bureau of forensic clinical researchers conducted a study to determine the eye drops in the human body PMI inference, is also promising.And they also determine the most potential metabolites, as a biomarker of this analysis.

Through the use of brooke Avance III nuclear magnetic resonance spectrometer, biomarkers to identify the metabolites

The team from the human body with different PMI interval collected blood, AH, and the VH and the processing of these samples, and then got to protein extract and in plasma, AH in VH to lipid extracts.Using brooke Biospin Avance HD 700 MHz NMR spectrometer III, by nuclear magnetic resonance (NMR) technology metabonomics qualitative analysis on these samples.

According to the obtained data, the researchers found in three samples of 42 kinds of metabolites.In this set of samples, there are 6 kinds of metabolites with all PMI in body fluids, showing the high linear positive correlation.They are hypoxanthine, choline, creatine, betaine, glutamic acid and glycine.

The metabolite concentrations in the blood is chaotic, and compared with the blood, AH and the concentration change of the VH is slower and more smoothly.These data strongly support the previous analyses of metabonomics in animals, so can get the following conclusion: AH and VH is more suitable for PMI inference.

In these two kinds of eye drops, the researchers observed the strongest in the VH PMI linear positive correlation with the concentration of metabolites.Due to the cause of the phenomenon of the VH is of high viscosity, and compared with AH, its high degree of isolation with vascular system.AH, however, the sampling process has lower blood pollution risk - it can avoid errors in the experiment.And because the AH is very low in protein and lipid, so the more simple sample preparation.

Analysis in combination with a variety of biomarkers, which can improve the accuracy of the PMI inference

So far, the vast majority of research articles in this field are focused on the use of a kind of metabolite as a biomarker for PMI inference.However, the study identified the six potential, biomarkers can be used as a PMI metabolites.Therefore, the researchers also performed based on a variety of metabonomics analysis of metabolites.

AH the creatine, choline and betaine, and the VH of creatine and betaine - these metabolites revealed a strongest positive correlation with PMI.Use two or three such biomarker combination, can significantly reduce the error of the PMI inference.It is interesting to note that use more than three of these metabolites and cannot be further improve the accuracy of the PMI inference.

conclusion

The study provides support for animal data, shows that compared with the plasma, the liquid on isolated anatomy is more suitable for PMI reasoned that because the metabolic changes more slowly and were relatively stable.AH and VH can provide accurate and reliable information.Although the VH data more accurate, but AH sample preparation, easier to less risk of contamination.

Due to these metabolites (hypoxanthine, choline, creatine, betaine, glutamic acid and glycine) - they all linear positive correlation with the PMI, the authors suggest, therefore, can be used in the analysis combined with the several biomarkers, in order to improve the veracity and reliability of PMI inference and minimize the error.

A set of applied in forensic medicine, comprehensive solution

Brooke can provide a set of the most comprehensive for forensic analysis solutions, including: to drugs and stimulants, chemical warfare agents (CWA) for identification and quantitative analysis, the explosives were characterized, to test the food adulteration, art and document forgery, and environmental forensics direction detection, such as waste analysis and crime scene investigation (such as glass, fiber and shooting residue analysis).Brooke r&d technology not only can be applied to daily routine analysis, can also be used for research and development and improvement of the new method for research of this paper (for example).Brooke's goal is to make law enforcement to legal process provides a consistent and powerful data - the society will be more safety.

References:

1. Zelentsova, e. A., et al. (2020). The Post Mortem - Changes in Metabolomic Profiles of Human Serum, Aqueous Humor and Vitreous Humor. Metabolomics. https://doi.org/10.1007/s11306-020-01700-3.