Study of Root Transparency in Different Postmortem Intervals Using Scanning Electron Microscopy

In the fields of forensics, the identification of human remains is a recurrent problem. The estimated age at death is one of the copious criteria to be evaluated. In adult teeth, the height of the root dentin transparency is used to estimate age. However, in archaeological material, this phenomenon appears inconstant. The aim of this work was to observe the structural modifications of the sclerotic dentin in the teeth for different postmortem intervals. The study included two parts (retrospective and prospective study) with 21 human monoradicular teeth, from bodies donated to medical science with postmortem intervals (PMIs) of 0, 1, 2 and 5 years and archeological excavation. After inclusion based on resin, section and polishing, the samples were analyzed with a scanning electron microscope (SEM) JSM-7800F®, and the procedure was completed via a semiquantitative analysis of calcium and phosphorus using EDX microanalysis. The analysis showed the existence of tubular and chemical modifications of sclerotic dentin at different PMIs. Our SEM study allowed us to observe a difference in tubule aspects linked to an increased PMI: the loss of peritubular collar and the lumen obstruction of tubules with a hyperdense material. Microanalysis highlighted variations in phosphocalcic ratios among the different groups, especially in the pulp area and the canine. Our hypotheses that explain these differences are based on the postmortem modifications of the crystals of the mineral phase of sclerotic dentin under the influence of chemical and/or bacterial action.

[Characteristics of structural morphological changes of the liver depending on the prescription of death coming]

The purpose of the work is to analyze the literature data devoted to the study of postmortem morphological changes in liver tissue and their use to determine the prescription of death. Postmortem changes are based on the processes of postmortem redistribution of blood and autolysis, the speed and severity of development of which depends primarily on the lifetime pathology, as well as external temperature and humidity during storage of the corpse. The onset of biological death naturally entails the development of postmortem changes in the liver, manifested by a decrease in temperature, violations of the structure of organelles, cells and organ tissue as a whole. The determination and evaluation of developing postmortem morphological changes is necessary both for differential diagnosis with lifetime-developed pathological processes, and for determining the prescription of death coming. This necessitates research to study the features of the development of postmortem changes and to develop ways to assess them to determine the prescription of death coming.

[Characteristics of histochemical, molecular genetic and radiation-induced liver changes depending on the postmortem interval]

The aim of this study is to analyze literature data on postmortem changes in the liver and their use in determination of postmortem interval. Biological death expectedly causes the development of postmortem disorders not only in the liver structure, but also changes in its biochemical and histochemical parameters. Literature data about changes of histochemical, immunohistochemical and biomolecular characteristics of liver tissue, as well as bacterial migration to the liver depending on the duration of postmortem period, are presented. The effectiveness of radiology for visualization of postmortem changes and, accordingly, for determining the postmortem interval is noted.

Rates of refusal of clinical autopsies among HIV-positive decedents and an overview of autopsies in Uganda

Background: Human immunodeficiency virus (HIV)-related mortality remains high in sub-Saharan Africa. Clinical autopsies can provide invaluable information to help ascertain the cause of death. We aimed to determine the rate and reasons for autopsy refusal amongst families of HIV-positive decedents in Uganda. Methods: We consented the next-of-kin for post-mortem examinations among Ugandan decedents with HIV from 2017-2020 at Kiruddu National Referral Hospital. For those who refused autopsies, reasons were recorded. Results: In this analysis, 165 decedents with HIV were included from three selected wards at Kiruddu National Referral Hospital.  Autopsy was not performed in 45% of the deceased patients; the rate of autopsy refusal was 36%. The most common reasons for autopsy refusal were time constraints (30%), family satisfaction with clinical diagnosis (15%), fear of disfigurement of the remains (15%), and lack of perceived benefit (15%). By seeking consent from multiple family members and clearly explaining to them the purpose of performing the autopsy, we found a reduction in the rate of autopsy refusal among relatives of the deceased patients at this hospital compared to previous studies at the same site (36% vs. 60%). Conclusions: We found lower rates of autopsy refusal compared to previous studies at the same site. This underscores the importance of clearly explaining the purpose of autopsies as they increase active sensitization about their relevance and dispel myths related to autopsies among the general population. Good, culturally sensitive, and timely explanations to the family of the benefits of autopsy increase the rate of obtaining permission. Building capacity for performing autopsies by training more pathologists and increasing laboratory resources to decrease the turn-around-time for autopsy reports and extending these services to peripheral health facilities could improve autopsy acceptance rates.

Rates of refusal of clinical autopsies among HIV-positive decedents and an overview of autopsies in Uganda

Background: Human immunodeficiency virus (HIV)-related mortality remains high in sub-Saharan Africa. Clinical autopsies can provide invaluable information to help ascertain the cause of death. We aimed to determine the rate and reasons for autopsy refusal amongst families of HIV-positive decedents in Uganda. Methods: We consented the next-of-kin for post-mortem examinations among Ugandan decedents with HIV from 2017-2020 at Kiruddu National Referral Hospital. For those who refused autopsies, reasons were recorded. Results: In this analysis, 165 decedents with HIV were included from three selected wards at Kiruddu National Referral Hospital.  Autopsy was not performed in 45% of the deceased patients; the rate of autopsy refusal was 36%. The most common reasons for autopsy refusal were time constraints (30%), family satisfaction with clinical diagnosis (15%), fear of disfigurement of the remains (15%), and lack of perceived benefit (15%). By seeking consent from multiple family members and clearly explaining to them the purpose of performing the autopsy, we found a reduction in the rate of autopsy refusal among relatives of the deceased patients at this hospital compared to previous studies at the same site (36% vs. 60%). Conclusions: We found lower rates of autopsy refusal compared to previous studies at the same site. This underscores the importance of clearly explaining the purpose of autopsies as they increase active sensitization about their relevance and dispel myths related to autopsies among the general population. Good, culturally sensitive, and timely explanations to the family of the benefits of autopsy increase the rate of obtaining permission. Building capacity for performing autopsies by training more pathologists and increasing laboratory resources to decrease the turn-around-time for autopsy reports and extending these services to peripheral health facilities could improve autopsy acceptance rates.

Postmortem Changes of Female External Genitalia and Their Importance in Suspected Sexual Abuse

Examination of the female external genitalia to assess for sexual abuse is performed in living individuals, and the interpretation of the findings is based on evidence-based studies. However, in the deceased, no such studies are available, and postmortem changes could present as suspicious findings that can be mistaken for trauma. Patches of discoloration in the hymen were reported previously in one case as hypostasis (i.e., livor and lividity), and based on this finding, it was listed as a finding that is not associated with trauma. This was a retrospective study that was conducted in the Center of Forensic and Legal Medicine in Dammam, Saudi Arabia over a 4-year period. The study included 30 deceased women in whom photographic documentation of their external genitalia was assessed for postmortem changes. The postmortem interval ranged from less than 24 h to more than 100 days, and the ages of these deceased women were in the 20-40 year-old age group. In cases where the hymen, vagina, and/or fossa navicularis were clearly visible, none of these areas showed any hypostatic discoloration. A comparison between antemortem and postmortem appearance of the hymen in one case clearly showed the absence of hypostatic changes in the hymen. In conclusion, any discoloration of the external genitalia that is detected in a female decedent requires serious consideration.

Timing and Appearance of Postmortem Root Banding in Nonhuman Mammals

A study was undertaken using nonhuman mammal specimens to better understand environmental influences on postmortem hair root band (PMRB) formation and to see whether PMRBs would occur in nonhuman mammal hairs in a similar fashion to human hairs. Carcasses from surrounding roadways were the primary source of specimens for this study, augmented by donated deceased domestic pets. Sections of pelt from each specimen were placed in controlled environmental conditions while the remainder of the carcass was left in a secure outdoor setting. Hair samples were collected daily from outdoor and control specimens and examined for evidence of PMRBs. Several environmental factors were also recorded on a daily basis. Results demonstrate PMRBs can occur in nonhuman mammal hairs, and they have microscopic characteristics similar to human PMRBs. Factors found to correlate with PMRB formation include postmortem interval, temperature, pH, and the formation and subsequent volatilization of ammonia from the surrounding tissue.

An Aquatic Decomposition Scoring Method to Potentially Predict the Postmortem Submersion Interval of Bodies Recovered from the North Sea

This study aimed to develop an aquatic decomposition scoring (ADS) method and investigated the predictive value of this method in estimating the postmortem submersion interval (PMSI) of bodies recovered from the North Sea. This method, consisting of an ADS item list and a pictorial reference atlas, showed a high interobserver agreement (Krippendorff's alpha ≥ 0.93) and hence proved to be valid. This scoring method was applied to data, collected from closed cases-cases in which the postmortal submersion interval (PMSI) was known-concerning bodies recovered from the North Sea from 1990 to 2013. Thirty-eight cases met the inclusion criteria and were scored by quantifying the observed total aquatic decomposition score (TADS). Statistical analysis demonstrated that TADS accurately predicts the PMSI (p < 0.001), confirming that the decomposition process in the North Sea is strongly correlated to time.

Capillary Network Morphometry of Pig Soleus Muscle Significantly Changes in 24 Hours After Death

Capillary network characteristics are invaluable for diagnostics of muscle diseases. Biopsy material is limited in size and mostly not accessible for intensive research. Therefore, especially in human tissue, studies are performed on autopsy material. To approach the problem whether it is reliable to deduce hypotheses from autopsy material to explain physiological and pathological processes, we studied capillarity in pig soleus muscle 1 and 24 hr after death. Capillaries and muscle fibers were immunofluorescently marked, and images were acquired with a confocal microscope. Characteristics of the capillary network were estimated by image analysis methods using several plugins of the Ellipse program. Twenty-four hours after death, the measured characteristics of the capillary network differ by up to 50% when compared with samples excised 1 hr after death. Muscle fiber diameter, the measured capillary length, and tortuosity were reduced, and capillary network became more anisotropic. The main postmortem change that affects capillaries is evidently geometric deformation of muscle tissue. In conclusion, when comparing results from biopsy samples with those from autopsy samples, the effect of postmortem changes on the measured parameters must be carefully considered.

Estimation of time since death based on light microscopic, electron microscopic, and electrolyte analysis in the gingival tissue

Background:

Estimation of time since death is an important parameter in forensic science. Although there are various methods available, precise estimation is still to be established.

Aim:

The present study aimed to evaluate the histological and ultrastructural changes in the gingival tissue along with the changes in electrolyte levels (sodium, potassium, calcium, and magnesium) among the three groups which included normal, 2, and 4 h since death.

Materials and Methods:

For light microscopic examination and electrolyte analysis, five normal gingival tissue samples were collected from patient following impaction procedure and five gingival tissue samples were obtained from postmortem specimen at 2 and 4 h since death. Each sample was divided into two parts. The first part was fixed in 10% formalin solution for the light microscopic analysis, and microscopic changes were observed between the groups. The second part was snap frozen at −80°C, until measurement of electrolyte using inductively coupled plasma-optical emission spectrometer, and the values were compared among the groups using Kruskal–Wallis test. For electron microscopic examination 2 and 4 h postmortem, gingival tissue samples were collected from the same individual and immediately fixed in 2.5% buffered glutaraldehyde, and the ultrastructural changes were compared with the normal gingival tissue.

Results:

The light microscopic changes were observed as early as 2 h since death, but there was no significant difference observed between 2 and 4 h postmortem samples whereas ultrastructurally significant difference in morphology was observed between 2 and 4 h postmortem gingival tissue. Our results can confirm histomorphological changes within 2 and 4 h since death.

[The possibilities for diagnostics of prescription of death coming based on the changes in the lumbar intervertebral disks (the comparison of the morphological, immunohistochemical and topographical findings)]

The objective of the present study was the comprehensive analysis of the postmortem changes in the lumbar intervertebral disks within different periods after death. A total of seven vertebromotor segments were distinguished in the lumbosacral region of the vertebral column based on the examination of 7 corpses. All these segments were divided into three groups in accordance with the prescription of death coming as follows: up to 12 hours (group 1), between 12 and 24 hours (group 2), and between 24 and 36 hours (group 3) after death. The models of the segments thus obtained were subjected to the study by means of diffusion weighted MRI. The removed intervertebral disks were used for morphological and immunohistochemical investigations. The comparison of the diffusion coefficients (DI) revealed the significant difference between the intervertebral disks assigned to groups 1 and 2 (p<0.01). The number of the cells in the pulpal core, the vertebral end plate, and the fibrous ring in all the above groups of the intervertebral disks was significantly reduced (p<0.01). The analysis of the correlation dependence between cell density and diffusion coefficients has demonstrated the well apparent relationship between these characteristics of the intervertebral disks comprising groups 1 and 2. It is concluded that diffusion weighted MRI in the combination with the calculation of diffusion coefficients for the intervertebral disks provides a tool for diagnostics of prescription of death coming as confirmed by the results of the morphometric studies and immunohistochemical analysis.

Protein Kinase Activity Decreases with Higher Braak Stages of Alzheimer's Disease Pathology

Alzheimer’s disease (AD) is characterized by a long pre-clinical phase (20–30 years), during which significant brain pathology manifests itself. Disease mechanisms associated with pathological hallmarks remain elusive. Most processes associated with AD pathogenesis, such as inflammation, synaptic dysfunction, and hyper-phosphorylation of tau are dependent on protein kinase activity. The objective of this study was to determine the involvement of protein kinases in AD pathogenesis. Protein kinase activity was determined in postmortem hippocampal brain tissue of 60 patients at various stages of AD and 40 non-demented controls (Braak stages 0-VI) using a peptide-based microarray platform. We observed an overall decrease of protein kinase activity that correlated with disease progression. The phosphorylation of 96.7% of the serine/threonine peptides and 37.5% of the tyrosine peptides on the microarray decreased significantly with increased Braak stage (p-value <0.01). Decreased activity was evident at pre-clinical stages of AD pathology (Braak I-II). Increased phosphorylation was not observed for any peptide. STRING analysis in combination with pathway analysis and identification of kinases responsible for peptide phosphorylation showed the interactions between well-known proteins in AD pathology, including the Ephrin-receptor A1 (EphA1), a risk gene for AD, and sarcoma tyrosine kinase (Src), which is involved in memory formation. Additionally, kinases that have not previously been associated with AD were identified, e.g., protein tyrosine kinase 6 (PTK6/BRK), feline sarcoma oncogene kinase (FES), and fyn-associated tyrosine kinase (FRK). The identified protein kinases are new biomarkers and potential drug targets for early (pre-clinical) intervention.

Postmortem Changes in Animal Carcasses and Estimation of the Postmortem Interval

A thorough understanding of the physical and chemical changes that occur in the body after death is critical for accurate interpretation of gross and microscopic pathology at autopsy. Furthermore, knowledge of the postmortem processes and the factors that affect them will aid in the estimation of the postmortem interval (PMI). The estimation of the PMI is important in many human and animal death investigations. Despite many decades of research, accuracy in estimation of the time of death has not significantly improved, and no single method can be reliably used to accurately estimate the time of death. Great care should be taken when formulating such an estimate, for it is dependent on multiple circumstantial and environmental factors, and the accuracy and precision of the estimate decrease as the PMI increases. The majority of the research in the field has been conducted on human bodies, but many relevant conclusions may be drawn regarding the expected postmortem changes in animals and the estimation of the PMI. The veterinary pathologist must use great caution when attempting to extrapolate data and apply formulas designed for use in humans. Methods reviewed include gross changes, microscopic changes, temperature-based methods, postmortem chemistry, molecular methods, microbial assay, ocular changes, radiography, entomology, and others. Although only several of these methods are currently practical for use in the workup of cases, it is expected that future research will result in improved techniques with enhanced accuracy in the estimation of the PMI, which will benefit both human and veterinary forensic investigations.

The Use of the Developmental Rate of the Aquatic Midge Chironomus riparius (Diptera, Chironomidae) in the Assessment of the Postsubmersion Interval

Nonbiting midges (Diptera, Chironomidae) are the most abundant members of the fauna associated with submerged carcasses, but their use in the medicolegal context is very restricted because of their complex ontogeny. In this case, the corpse of a woman was recovered in late spring from a river in Granada (Iberian Peninsula). It showed obvious signs of long permanence in the aquatic environment and, along with pulmonary and microscopical analyses, led to the conclusion that the cause of death was drowning. Several larvae-like specimens were sampled from the scalp and later identified by morphological external features as IV instar larvae of Chironomus riparius Meigen, 1804 (Diptera, Chironomidae). Sequencing of cytochrome oxidase subunit I was performed to confirm the identification. The knowledge of the biology of C. riparius at low temperatures was critical to assess a postsubmersion interval of 16-17 days.