Inferring the Postmortem Interval of Rat Cadaver after Boiling Water Treatment Based on Microbial Community Succession

Background:In forensic investigations,accurate estimation of the postmortem interval(PMI)is an important task,but also an ongoing challenge.Especially in cases where the cadaver has been specially treated,for example,by boiling,the determination of PMI becomes extremely difficult.Previous studies have shown that the succession of the microbial community after decomposition of the cadaver can be used to infer PMI.However,the feasibility of determining the PMI of boiled cadavers has not yet been demonstrated.Aims and Objectives:The main objective of this study was to test whether we can infer PMI of boiled cadavers based on the succession of microbial communities.Materials and Methods:SD rats were killed by cervical dislocation.Subsequently,the rat cadavers were divided into the case(boiled cadavers)and control(unboiled cadavers)groups.Rectal samples were collected from the rats for 45 days and at nine time points.High-throughput sequencing of the 16S rRNA gene was performed to characterize the microbial community in the rectum.Results:The results showed that the composition and relative abundance of bacterial communities at the phylum level were significantly different between the case and control groups.The alpha diversity of the microbial community showed a decreasing trend with the decomposition process.Principal coordinate analysis showed that the case and control groups had obvious patterns along the succession of microbial communities.The rectal microbial communities showed a significant linear trend in the time course of decomposition.A random forest model was used to infer PMI.The goodness-of-fit(R2)of the model was 68.00%and 84.00%,and the mean absolute errors were 2.05 and 1.48 days within 45 days of decomposition for the case and control groups,respectively.Conclusions:Our results suggest that microbial community succession could be a potential method to infer PMI of boiled cadavers.

Comparison of the Concentrations of Lidocaine in Different Body Fluids/Tissues after Subarachnoid Space and Intravenous Administration of a Lethal Dose of Lidocaine

The objective of the study was to compare the concentration of lidocaine in different body fluids/tissues after subarachnoid space and intravenous administrations of a lethal dose of lidocaine.Totally 18 dogs were used in the experiment.Six dogs were given subarachnoid anesthesia,another were given an intravenous injection of a dose of 75 mg/kg weight of lidocaine hydrochloride in 5 min and the last 6 dogs were used as the blank control dogs and given a subarachnoid space injection or a femoral artery injection of the same volume of sodium chloride.As soon as its vital signs disappeared,each dog was dissected and the specimen,such as brain,cerebrospinal fluid(CSF)in lateral ventricle,CSF in subarachnoid space,spinal cord(cervical spinal cord,thoracic spinal cord,lumbar spinal cord,and waist spinal cord),heart,lung,liver,spleen,kidney,bile,urine,heart blood,peripheral blood,muscle in injection location,and muscle in no injection location,were collected for analysis of lidocaine immediately.Analysis was performed with gas chromatography‑mass spectrometry(GC‑MS).From the maximum to the minimum,the order of lidocaine concentration detected in the subarachnoid space‑administered dogs was as follows:CSF in subarachnoid space,waist spinal cord,thoracic spinal cord,CSF in lateral ventricle,lumbar spinal cord,cervical spinal cord,lung,kidney,muscle in injection location,heart,brain,spleen,heart blood,liver,peripheral blood,bile,muscle in no injection location,and urine.The order of lidocaine concentration detected in the intravenously administered dogs was as followed:Kidney,heart,lung,spleen,brain,liver,peripheral blood,bile,heart blood,cervical spinal cord,thoracic spinal cord,muscle in injection location,lumbar spinal cord,muscle in no injection location,CSF in subarachnoid space,urine,and CSF in lateral ventricle.The maximum concentration of lidocaine was detected in the subarachnoid space CSF of subarachnoid space‑administered dead dogs,while in intravenously injected dead dogs,the maximum concentration of lidocaine was detected in the kidney.Our study provides some useful data for the forensic identification of epidural anesthesia accidents to decide the way the lidocaine enters the body.

Characteristics of Suicides Caused by Drug Overdose in the State of Maryland

Suicidal drug overdose is a major public health issue.In the United States,every year more than 33,000 people commit suicides.Our study focused on the characteristics of suicide victims in the state of Maryland.Material and methods:This study was a retrospective review of autopsy cases of all suicide deaths caused by drug(s)or drug(s)with alcohol intoxication investigated by the OCME in Maryland over a 7-year period from January 2004 to December 2011.All deaths investigated by the OCME that require autopsy examination are subject to comprehensive toxicology testing for drugs and alcohol.The screen tests were performed using gas chromatography(GC)and radioimmunoassay techniques.All detected drugs and/or metabolites were confirmed using GC-mass spectrometry(GC-MS).Results:From 2004 to 2011,434 deaths were certified as suicide.Of the 434 suicidal overdose deaths,84%were white,11%were African-American,and about 5%were either Hispanic or Asian.The male and female ratio was almost equal.Their ages ranged 15-82 years.Of the 434 suicidal drug overdose deaths,277 victims(63.8%)consumed a single drug type and 157(36.2%)consumed more than one type of drug.Of the 277 single-drug overdose cases,71.1%suicides were due to prescription drugs,23.5%due to over-the-counter drugs,and 5.4%due to street/recreational drugs.Among single-type prescription drugs,analgesic(N=76),antidepressant(N=45),and neuroleptic(N=35)classes were the three leading type of drugs used in suicidal deaths.Oxycodone,morphine,quetiapine,and amitriptyline were the most common prescription drugs in suicidal overdose.Diphenhydramine was the leading over-the-counter drug.Of the 157 victims who consumed more than one drug,combined prescription drugs were present in 54.1%,mixed prescription and overthe-counter drugs in 29.3%,and prescription drugs/over-the-counter drugs and street drugs in 16.6%of cases.Of the multiple-drug overdose suicides,66.2%cases involved antidepressants.Discussion:Suicide is found in every age,racial,and ethnic group.In the USA,poisoning is thethird-leading method of suicide,following firearm injuries and hanging/strangulation.Our study indicates that prescription drugs,such as those in the opioid analgesic,neuroleptic,and antidepressant class(e.g.,oxycodone,morphine,quetiapine,amitriptyline,doxepin,and citalopram),are of special concern in the context of suicidal overdose deaths in the state of Maryland.Therefore,addressing the problems of intentional drug overdose in our society is worthy of public attention.