Implication of High-mobility group box-1 and skin post mortem changes in estimation of time passed since death: Animal and human study

Determination of postmortem interval (PMI) is one of the goals of the forensic autopsy. The study aimed to correlate the postmortem skin changes and High-mobility group box-1 (HMGB1) alterations in serum and skin immunohistochemical staining with time since death. We used animal and human specimens; forty adult male albino rats were dissected to obtain samples at PMI (0, 3, 6, 12, 24 h); forty human medicolegal autopsy cases with a known time of death (within the first 24 h PMI). Cases were classified into 5 groups according to the PMI: I (0 h); II (≤3h); III (4 to 6); IV (7 to 12); V (13 to 24) hour intervals after death; blood and full-thickness skin samples were collected from both models. Results showed a significant time-dependent elevation in serum HMGB1 levels along with its overexpression in immunohistochemically stained skin tissue. Also, the degree of histopathological changes in epidermis, dermis, and hypodermis progressively increased with PMI in both models. The timetable of postmortem skin histological changes, serum HMGB1 concentration, and immunoexpression for HMGB1 proteins in skin tissues has a profile that could serve as actual and simply convenient parameters for accurate determination of postmortem intervals in both models. HMGB1 displayed a pivotal role in the estimation of PMI at the examined periods.     

Analysis of postmortem changes in internal organs and gases using computed tomography data

Postmortem computed tomography (PMCT) is a useful method to identify various causes of death and measure the volume of internal organs and gases. The purpose of this study was to investigate postmortem changes as measured by PMCT, and the relationship between the volume of organs and gases and postmortem interval (PMI).Forty-six cadavers (22 men, 24 women) were examined by CT before autopsy. The volumes of the lungs, intrahepatic gas, and intrarectal gas were measured by CT using a workstation. A stepwise regression analysis was used to establish a predictive equation to ascertain the measured volume using factors including sex, age, height, body mass index (BMI), body surface area (BSA), and PMI. For estimation of PMI, stepwise regression analysis was used.In the equations for each measured volume, height, diaphragmatic height, and BSA were adopted for the left lung; height and diaphragmatic height were adopted for the right lung; PMI was adopted for intrahepatic gas; and sex and PMI were adopted for intrarectal gas. In the PMI equations, left lung volume, intrahepatic gas, and intrarectal gas were adopted together with sex, weight, and BMI.Values of intrahepatic gas decreased with postmortem changes, while intrarectal gas increased. This may be useful in investigation of postmortem changes. It will be necessary to include other parts of the intestine and to analyze volume changes in gases from these parts after death.     

The changes of attenuated total reflection-Fourier transform infrared after rat’s death under different humidity conditions

Estimation of the time since death (post-mortem interval, PMI) is one of the most difficult problems in forensic investigations and many methods currently are utilized to estimate the PMI. The goal of this study was to investigate the changes of attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra of rat tissues from post-mortem time zero to 6 days in 40% and 80% humidity conditions. The spectra of rat tissues displayed similar change tendencies with increasing post-mortem interval in 40% and 80% humidity conditions, and the changes were more obvious in 80% humidity. Our study further confirmed that humidity was a factor affecting the estimation of PMI.     

Drowning versus postmortem submersion: Biochemical and histopathological examination and estimation of postmortem intervals (an experimental study)

Estimation of the postmortem interval (PMI) is a very essential task for forensic experts especially in criminal cases. drowning is still the most difficult tasks for forensic pathologists to be diagnosed and differentiated from a body disposed of in water following death especially after long post-mortem period. The objective of this study was to estimate the PMI in drowning in comparison to postmortem submersion using mRNA expression of AQP1 in addition to histological and immunohistochemical examination of caspase-3 in the adrenal and thyroid glands of adult albino rats. Adult albino rats were divided into 2 groups; group A (drowning) and group B (post-mortem submersion). Thyroid and adrenal glands were examined at different PMI. The results revealed significant differences at AQP1 levels between drowning and postmortem submersion at different PMI. Histological changes and caspase-3 expression immunologically in both glands were helpful.     

Measurement of temperature changes in cooling dead rats using magnetic resonance thermometry

Magnetic resonance imaging thermometry has been introduced as a technique for measurement of temperature changes in cooling dead rats. Rat pelvic magnetic resonance images were acquired sequentially more than 2 h after euthanasia by halothane overdose. A series of temperature difference maps in cooling dead rats was obtained with calculating imaging phase changes induced by the water proton frequency shift caused by temperature changes. Different cooling processes were monitored by the temperature difference maps in the rats. Magnetic resonance imaging thermometry applied in the study of laboratory animals could theoretically reproduce a variety of causes of death with different environmental conditions. Outcomes from experimental animal studies could be translated into a temperature-based time of death estimation in forensics.     

Estimating the postmortem interval using microbes: Knowledge gaps and a path to technology adoption

Microbes have potential to be used as physical evidence for forensic science because they are ubiquitous and have predictable ecologies. With the advent of next generation sequencing technology and the subsequent boost to microbiome science (study of the genes and molecules of microbial communities), it has become possible to develop new microbial-based tools for forensic science. One promising approach is the use of microbial succession during the ecological process of decomposition to estimate the time since death, or postmortem interval (PMI). This microbial clock of death is developed by building a regression model using microbiome data collected from postmortem samples (e.g. swab of skin) with known PMIs. In a death investigation, a similar sample type (e.g. swab of skin) would be collected, the microbes profiled using DNA sequencing, and the microbes would be matched to a point on the clock (i.e. the regression model). Recent research by several independent scientific teams has provided a proof of concept for this new microbiome forensic tool. However, developing and transitioning new forensic science technologies into the justice system requires overcoming scientific, investigative, and legal hurdles. In this article, I address the apparent knowledge gaps in the science of microbiome technology to estimate PMI, and discuss a path for bringing this technology into the justice system.     

von Willebrand factor in cadaveric urine for forensic investigation

Preliminary experimental study of urinary von Willebrand factor (VWF) concentration was undertaken to evaluate the utility of this parameter in forensic investigations. ELISA was used to measure VWF concentration. Correlations of urinary VWF with cause of death and postmortem interval (PMI) were ascertained. As PMI advanced, urinary VWF increased but plasma VWF did not. Cause of death was not significantly correlated with VWF. This study indicated the possibility that urinalysis would be helpful to estimate PMI.     

Exploring postmortem succession of rat intestinal microbiome for PMI based on machine learning algorithms and potential use for humans

The microbial communities may undergo a meaningful successional change during the progress of decay and decomposition that could aid in determining the post-mortem interval (PMI). However, there are still challenges to applying microbiome-based evidence in law enforcement practice. In this study, we attempted to investigate the principles governing microbial community succession during decomposition of rat and human corpse, and explore their potential use for PMI of human cadavers. A controlled experiment was conducted to characterize temporal changes in microbial communities associated with rat corpses as they decomposed for 30 days. Obvious differences of microbial community structures were observed among different stages of decomposition, especially between decomposition of 0–7d and 9–30d. Thus, a two-layer model for PMI prediction was developed based on the succession of bacteria by combining classification and regression models using machine learning algorithms. Our results achieved 90.48% accuracy for discriminating groups of PMI 0–7d and 9–30d, and yielded a mean absolute error of 0.580d within 7d decomposition and 3.165d within 9–30d decomposition. Furthermore, samples from human cadavers were collected to gain the common succession of microbial community between rats and humans. Based on the 44 shared genera of rats and humans, a two-layer model of PMI was rebuilt to be applied for PMI prediction of human cadavers. Accurate estimates indicated a reproducible succession of gut microbes across rats and humans. Together these results suggest that microbial succession was predictable and can be developed into a forensic tool for estimating PMI.     

Methods for determining time of death

Medicolegal death time estimation must estimate the time since death reliably. Reliability can only be provided empirically by statistical analysis of errors in field studies. Determining the time since death requires the calculation of measurable data along a time-dependent curve back to the starting point. Various methods are used to estimate the time since death. The current gold standard for death time estimation is a previously established nomogram method based on the two-exponential model of body cooling. Great experimental and practical achievements have been realized using this nomogram method. To reduce the margin of error of the nomogram method, a compound method was developed based on electrical and mechanical excitability of skeletal muscle, pharmacological excitability of the iris, rigor mortis, and postmortem lividity. Further increasing the accuracy of death time estimation involves the development of conditional probability distributions for death time estimation based on the compound method. Although many studies have evaluated chemical methods of death time estimation, such methods play a marginal role in daily forensic practice. However, increased precision of death time estimation has recently been achieved by considering various influencing factors (i.e., preexisting diseases, duration of terminal episode, and ambient temperature). Putrefactive changes may be used for death time estimation in water-immersed bodies. Furthermore, recently developed technologies, such as H magnetic resonance spectroscopy, can be used to quantitatively study decompositional changes. This review addresses the gold standard method of death time estimation in forensic practice and promising technological and scientific developments in the field.     

Establishing a minimum postmortem interval of human remains in an advanced state of skeletonization using the growth rate of bryophytes and plant roots

This paper illustrates the usefulness and efficiency of botanical evidence in establishing a minimum postmortem interval (PMI). The case under analysis refers to the remains of an adult male in an advanced state of skeletonization recovered from a wooded area in northern Portugal. The skeleton showed several taphonomical changes, which included the presence of green algae, bryophytes, and growing shrub roots in, around, and through the remains. By determining the age of both the bryophytes and shrub roots, it was concluded that the minimum amount of time elapsed since death was 3 years, to which several months or a few years have to be added to account for the complete decomposition of the remains. The disappearance of the presumptive individual had occurred 6 years before and is fully consistent with the estimate of the PMI. This report illustrates a novel use of bryophytes in a forensic setting.     

The assesment of retina and optic disc vascular structures in people who received CoronaVac vaccine

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus that is responsible for the current coronavirus disease pandemic and the vaccines currently developed are administered to prevent this infection. CoronaVac is a vaccine produced by the inactivated virus method. Ocular side effects such as anterior uveitis, optic neuritis, vision loss, episcleritis, allergic reaction and paracentral acute middle maculopathy have been reported after receiving CoronaVac vaccine. We assume that with this study, we can identify potential changes in posterior segment structures and posterior segment vascular density of people who received CoronaVac vaccine with optical coherence tomography angiography (OCTA) device.Material methodForty healthcare professionals who applied to the Health Sciences University Antalya Training and Research Hospital Ophthalmology Clinic for routine eye control were included in the study. The subjects who do not have any systemic condition and would be administered CoronaVac vaccine were chosen to assess. OCTA images of the patients before and within 1 week after vaccination were captured, then retinal and optic disc vascular values, foveal avascular zone (FAZ), choriocapillary blood flow (CBF), subfoveal choroidal thickness (SCT) and retinal thickness were analyzed and compared.ResultsTwo of the 40 patients had burning and stinging in the eye (5%), two of the 40 patients had redness (5%) and itching (5%) in the eye. 36 patients did not have any ocular symptoms.No statistically significant difference was found in the retinal and optic disc vascular density values, FAZ, CBF, SCT and retinal thickness values ​​of the patients before and after vaccination.ConclusionThis is among the first studies in the literature to evaluate the changes in retinal and optic disc vascular values ​​in people who received CoronaVac vaccine. In this study, we observed that CoronaVac vaccine did not effect retinal and optic disc vascular density significantly.     

Estimation of time since death from CSF electrolyte concentration in Bhopal region of central India

Estimation of time since death from sodium and potassium ion concentration levels in CSF (cerebrospinal fluid) was carried out in 100 medico legal autopsies with known time of death in the department of Forensic medicine, Gandhi Medical College in Bhopal region of Central India. CSF was aspirated from lateral ventricles after opening the skull and dura, and concentration of these ions were estimated by flame photometry. Results revealed a significant correlation of sodium and potassium ions in CSF up to 25 h of time since death, with average per hour rise of 1.21 meq/h for potassium and fall of 1.115 meq/h for sodium ions. A useful relationship between sodium potassium ion ratio and PMI (post-mortem interval) was also elicited. The study concludes that changes in CSF electrolyte is a significant parameter to estimate time since death.     

An experimental study on investigating the postmortem interval in dichlorvos poisoned rats by GC/MS-based metabolomics

The estimation of the postmortem interval (PMI) is always a key issue in forensic science. Although many attempts based on metabolomics approaches have been proven to be feasible and accurate for PMI estimation, there have been no reports regarding the determination of the PMI in acute dichlorvos (DDVP) poisoning. In this study, all rats were killed by acute DDVP poisoning at a dose three fold the oral LD₅₀ (240 mg/kg). Gas chromatography-mass spectrometry (GC/MS) was applied to investigate the metabolic profiling of blood samples at various times after death up to 72 h. A total of 39 metabolites were found to be associated with PMI, and the combinations of various numbers of metabolites were used to establish support vector regression (SVR) models to investigate the PMI. The SVR model constructed by 23 metabolites had a minimum mean squared error (MSE) of 5.49 h for the training set. Then, the SVR model was validated by prediction set with an MSE of 10.33 h, suggesting good predictive ability of the model for investigating the PMI. The findings demonstrated the great potential of GC/MS-based metabolomics combined with the SVR model in determining the PMI of DDVP poisoned rats and provided an experimental basis for the application of this approach in investigating the PMI of other toxicants.     

Eye function and physiology following a 161-km foot race

Significant visual impairment occurs in a small percentage of ultramarathon participants and is thought to be due to corneal edema. Yet, the usual effects of prolonged exercise on the eye have not been previously reported. Eight study volunteers who completed the 161-km Western States Endurance Run underwent pre-race and post-race binocular and monocular visual acuity, intraocular pressure, and corneal thickness measurements. None was symptomatic with visual impairment during the race and they demonstrated no changes from pre-race to post-race in visual acuity (p = 0.11–0.95 for right, left and combined), intraocular pressure (p = 0.11–0.43 for the both eyes) and corneal thickness (p = 0.30–0.99 for both eyes at three corneal areas). We conclude that there is no evidence that ultramarathon running has an acute effect on eye function or physiology when the runner has no symptoms or findings of visual impairment.     

Insects' colonization of human corpses in warm and cold season

The succession of insects is commonly used for estimation of the postmortem interval (PMI). In the warm season there are many insect species, which enable us to estimate the time of death, but in the cold season there are less species. For the estimation of a seasonal pattern, we examined 117 human corpses found in domestic environment during the year 2001. We found three typical 'summer species', active from May until October, three further species active from April until November. One blowfly species (Calliphora vicina) and the family of scuttle flies were active all over the year. These insects may be useful for PMI estimation in winter; however, further research concerning the developmental rate of scuttle flies is required. The distinct seasonal pattern of the early colonizing blowfly species allows to allocate the time of death to a particular time interval even in cases of long PMIs if empty puparia of these insects are found.     

Case report on Cochliomyia hominivorax (Coquerel, 1858) and Co. macellaria (Fabricius, 1775) (Calliphoridae,Diptera) myiasis prior to death: Implications on postmortem interval estimation

The most important contribution of forensic entomology is the estimation of the postmortem interval (PMI) or time since death. The forensic entomologist assumes that the biological clock of necrophagous insects that develop by feeding on cadaver tissues begins when the victim's biological clock is turned off. However, tissues can be invaded while the host is still alive (called myiasis), so the period of activity of necrophagous insects would not be indicative of PMI. The aim of this work was, through the presentation of a case report, to highlight the importance of expertise in the identification of necrophagous species associated with a corpse and their type of relationship in order to avoid an erroneous estimation of PMI. The corpse of a woman, missing for 14 days, was found outdoors in a small river 15 cm deep. Her corpse had numerous lesions infested with dipteran larvae that were collected during autopsy. Entomological evidence included second and third instar larvae of Cochliomyia hominivorax and Co. macellaria. The obligate parasitic nature of Co. hominivorax as a primary producer of myiasis and secondary of Co. macellaria allowed us to establish the time when the victim was still alive and from there to estimate the PMI.     

Radioactive isotope analyses of skeletal materials in forensic science: a review of uses and potential uses

A review of information that can be provided from measurements made on natural and anthropogenic radionuclide activities in human skeletal remains has been undertaken to establish what reliable information of forensic anthropological use can be obtained regarding years of birth and death (and hence post-mortem interval (PMI)). Of the anthropogenic radionuclides that have entered the environment, radiocarbon (¹⁴C) can currently be used to generate the most useful and reliable information. Measurements on single bones can indicate whether or not the person died during the nuclear era, while recent research suggests that measurements on trabecular bone may, depending on the chronological age of the remains, provide estimates of year of death and hence PMI. Additionally, ¹⁴C measurements made on different components of single teeth or on teeth formed at different times can provide estimates of year of birth to within 1–2 years of the true year. Of the other anthropogenic radionuclides, ⁹⁰Sr shows some promise but there are problems of (1) variations in activities between individuals, (2) relatively large analytical uncertainties and (3) diagenetic contamination. With respect to natural series radionuclides, it is concluded that there is no convincing evidence that ²¹⁰Pb dating can be used in a rigorous, quantitative fashion to establish a PMI. Similarly, for daughter/parent pairs such as ²¹⁰Po/²¹⁰Pb (from the ²³⁸U decay series) and ²²⁸Th/²²⁸Ra (from the ²³²Th decay series), the combination of analytical uncertainty and uncertainty in activity ratios at the point of death inevitably results in major uncertainty in any estimate of PMI. However, observation of the disequilibrium between these two daughter/parent pairs could potentially be used in a qualitative way to support other forensic evidence.     

猪胸部枪弹伤后荧光眼底造影早期观察

目的：利用荧光眼底造影技术探讨猪胸部枪弹伤远达效应致眼部组织结构、视网膜血流伤后改变,了解胸部枪弹伤后眼组织的损伤情况。方法：采用高速弹射击10只猪（20只眼）,建立胸部枪弹伤动物模型,对受试猪致伤前后不同时相点行眼底照相及荧光眼底造影,并作眼组织病理检查。结果：（1）眼底照相结果：伤后未见明显异常;（2）荧光眼底造影结果：伤后1 h耳-视网膜循环时间延长,较伤前有显著变化（P〈0.05）,伤后视网膜循环时间较伤前无显著改变;（3）病理结果：角膜上皮层肿胀、疏松,内皮层大量脱落,虹膜、睫状体、脉络膜、视网膜血管充血,血管内皮细胞部分脱落,视网膜神经纤维层水肿。结论：荧光眼底造影对胸部枪弹伤后,眼组织血流改变、视网膜功能的判断具有重要价值。     

Distinction between forensic evidence and dermatological findings

The external examination after death requires knowledge in forensics/pathology, dermatology, as well as associated diseases and age-related alterations of the skin. This article highlights some findings with forensic evidence versus dermatological findings.The lectures in forensic medicine should be structured interdisciplinarily, especially to dermatology, internal medicine, surgery, pathology, and toxicology in order to train the overlapping skills required for external and internal postmortem examinations.     

Estimation of PMI depends on the changes in ATP and its degradation products

Estimating the time since death, or postmortem interval (PMI), has been one of the biggest difficulties in modern forensic investigation. This study tests if the concentrations of breakdown products of adenosine triphosphate (ATP) correlate with PMI in multiple organs from rat. Brains, spleens, and kidneys of rats were harvested at different time points in carcasses maintained at 4 °C or 20 °C. High Performance Liquid Chromatography (HPLC) was used to quantify concentrations of metabolites related to ATP degradation. A K value (Kv = 100 × (Hx + HxR)/(ATP + ADP + AMP + IMP + HxR + Hx)) was calculated and correlated with PMI for each organ and temperature. The results indicate that the K value is a robust index for the estimation of PMI based on highly significant linear correlations between PMI and concentrations of ATP breakdown products. Compared with other current research methods, the changing tendency of ATP and its degradation products may be potentially a better way for the estimation of PMI in medico-legal practice.