Post-mortem enamel surface texture alteration during taphonomic processes—do experimental approaches reflect natural phenomena?

Experimental approaches are often used to better understand the mechanisms behind and consequences of post-mortem alteration on proxies for diet reconstruction. Dental microwear texture analysis (DMTA) is such a dietary proxy, using dental wear features in extant and extinct taxa to reconstruct feeding behaviour and mechanical food properties. In fossil specimens especially, DMTA can be biased by post-mortem alteration caused by mechanical or chemical alteration of the enamel surface. Here we performed three different dental surface alteration experiments to assess the effect of common taphonomic processes by simplifying them: (1) tumbling in sediment suspension to simulate fluvial transport, (2) sandblasting to simulate mechanical erosion due to aeolian sediment transport, (3) acid etching to simulate chemical dissolution by stomach acid. For tumbling (1) we found alteration to be mainly dependent on sediment grain size fraction and that on specimens tumbled with sand fractions mainly post-mortem scratches formed on the dental surface, while specimens tumbled with a fine-gravel fraction showed post-mortem formed dales. Sandblasting (2) with loess caused only negligible alteration, however blasting with fine sand quartz particles resulted in significant destruction of enamel surfaces and formation of large post-mortem dales. Acid etching (3) using diluted hydrochloric acid solutions in concentrations similar to that of predator stomachs led to a complete etching of the whole dental surface, which did not resemble those of teeth recovered from owl pellets. The experiments resulted in post-mortem alteration comparable, but not identical to naturally occurring post-mortem alteration features. Nevertheless, this study serves as a first assessment and step towards further, more refined taphonomic experiments evaluating post-mortem alteration of dental microwear texture (DMT).

Isolation and Characterization of Primary Retinal Microglia From the Human Post-mortem Eyes for Future Studies of Ocular Diseases

Microglia, the primary resident immunocytes in the retina, continuously function as immune system supervisors in sustaining intraocular homeostasis. Microglia relate to many diseases, such as diabetic retinopathy, glaucoma, and optic nerve injury. To further investigate their morphology and functions in vitro, a reliable culture procedure of primary human retinal microglia is necessary. However, the culture condition of microglia from the adult retina is unclear. Researchers created several protocols, but most of them were carried out on rodents and newborns. This study describes a protocol to isolate and characterize human primary retinal microglia from human post-mortem eyes. The whole procedure started with removing the retinal vessels, mechanical separation and enzymatic dissociation, filtration, and centrifugation. Then, we cultured the cell suspensions on a T-75 flask for 18 days and then shook retinal microglia from other retinal cells. We found numerous retinal microglia grow and attach to Müller cells 10 days after seeding and increase rapidly on days 14–18. Iba1 and P2RY12 were used to qualify microglia through immunofluorescence. Moreover, CD11b and P2RY12 were positive in flow cytometry, which helps to discriminate microglia from other cells and macrophages. We also observed a robust response of retinal microglia in lipopolysaccharide (LPS) treatment with proinflammatory cytokines. In conclusion, this study provides an effective way to isolate and culture retinal microglia from adult human eyes, which may be critical for future functional investigations.

Effect of Pre-Slaughter Practises and Early Post-Mortem Interventions on Sheep Meat Tenderness and Its Impact on Microbial Status

Tenderness, together with flavour, is the main quality trait that defines consumer acceptance of sheep meat. The factors affecting tenderness can be grouped as those influenced before slaughter, in the early post-mortem intervention and, finally, during the aging period. These factors have been extensively studied with respect to tenderness, but the impact of early post-mortem interventions and subsequent aging on the microbial quality of the final products has not been broadly reviewed to date. In this review, the authors summarize the most recent knowledge on lamb meat tenderness management and how such practices may impact the final meat quality, especially its microbial status. The impacts of pre-slaughter factors (age, sex, diet, genotype and transport) and post-mortem interventions (chilling regime, electrical stimulation, or hanging method), are described and comprehensively discussed.

The incidence and mortality of COVID-19 related TB infection in Sub-Saharan Africa: A systematic review and meta-analysis

Background Coronavirus disease 2019 (COVID-19) is also associated with other co-morbidities among with previous and current pulmonary tuberculosis (PTB). PTB is a risk factor for COVID-19, both in terms of severity and mortality, regardless of human immunodeficiency virus (HIV) status. However, there is less information available on COVID-19 associated with PTB in point of view incidence and mortality rates in sub-Saharan Africa (SSA) as a high burden TB region. This systematic review served to provide data synthesis of available evidence on COVID-19/PTB incidence and case fatality rates, and mortality rate found in clinical and post-mortem COVID-19/PTB diagnostics in SSA. Methods We conducted a systematic electronic search in the PubMed, Medline, Google Scholar, Medrxix and COVID-19 Global literature on coronavirus disease databases for studies including COVID-19 associated with PTB in sub-Saharan Africa. The main outcomes were the proportion of people with COVID-19 associated to current /or previous PTB and the case fatality associated to COVID-19/PTB. The combination method was based on methodological similarities in the included random effect model studies using Prometa 3 software. We further undertook sensitivity analysis and meta-regression. Results From the 548 references extracted by the literature search, 25 studies were selected and included in the meta-analysis with a total of 191, 250 COVID-19 infected patients and 11, 452 COVID-19 deaths. The pooled COVID-19/PTB incidence was 2% [1%-3%] and mortality of 10% [4%-20%]. The pooled estimates for case fatality rate among COVID-19/PTB were 6% [3%-11%] for clinical PTB diagnostic and 26% [14%-48%] for post-mortem PTB diagnostic. Meta-regression model including the effect sizes and cumulative COVID-19 cases (P= 0.032), HIV prevalence (P= 0.041) and TB incidence (P= 0.002) to explained high heterogeneity between studies. Conclusion As a summary, the incidence of TB associated with COVID-19 and case fatality rates are higher in SSA. However, COVID-19 associated to TB may be underreported in the studies conducted in SSA as the post-mortem TB diagnostic was higher. Large-scale cohort studies that adequately clear tool on previous and/or current TB diagnostic tools are required to confirmed COVID-19/TB incidence and case fatality in SSA.

Reactive astrocytes acquire neuroprotective as well as deleterious signatures in response to Tau and Aß pathology

Alzheimer’s disease (AD) alters astrocytes, but the effect of Aß and Tau pathology is poorly understood. TRAP-seq translatome analysis of astrocytes in APP/PS1 ß-amyloidopathy and MAPTP301S tauopathy mice revealed that only Aß influenced expression of AD risk genes, but both pathologies precociously induced age-dependent changes, and had distinct but overlapping signatures found in human post-mortem AD astrocytes. Both Aß and Tau pathology induced an astrocyte signature involving repression of bioenergetic and translation machinery, and induction of inflammation pathways plus protein degradation/proteostasis genes, the latter enriched in targets of inflammatory mediator Spi1 and stress-activated cytoprotective Nrf2. Astrocyte-specific Nrf2 expression induced a reactive phenotype which recapitulated elements of this proteostasis signature, reduced Aß deposition and phospho-tau accumulation in their respective models, and rescued brain-wide transcriptional deregulation, cellular pathology, neurodegeneration and behavioural/cognitive deficits. Thus, Aß and Tau induce overlapping astrocyte profiles associated with both deleterious and adaptive-protective signals, the latter of which can slow patho-progression.

Identifying gene expression profiles associated with neurogenesis and inflammation in the human subependymal zone from development through aging

The generation of new neurons within the mammalian forebrain continues throughout life within two main neurogenic niches, the subgranular zone (SGZ) of the hippocampal dentate gyrus, and the subependymal zone (SEZ) lining the lateral ventricles. Though the SEZ is the largest neurogenic niche in the adult human forebrain, our understanding of the mechanisms regulating neurogenesis from development through aging within this region remains limited. This is especially pertinent given that neurogenesis declines dramatically over the postnatal lifespan. Here, we performed transcriptomic profiling on the SEZ from human post-mortem tissue from eight different life-stages ranging from neonates (average age ~ 2 months old) to aged adults (average age ~ 86 years old). We identified transcripts with concomitant profiles across these decades of life and focused on three of the most distinct profiles, namely (1) genes whose expression declined sharply after birth, (2) genes whose expression increased steadily with age, and (3) genes whose expression increased sharply in old age in the SEZ. Critically, these profiles identified neuroinflammation as becoming more prevalent with advancing age within the SEZ and occurring with time courses, one gradual (starting in mid-life) and one sharper (starting in old age).

Assessment of Hydroxyethyl Starch (6% HES 130/0.4) Kidney Storage in Critically Ill Dogs: A Post-mortem Prospective Study

Objective: Intravenous hydroxyethyl starch (HES) solutions are potentially nephrotoxic due to rapid renal tissue uptake, subsequent osmotic nephrosis, and long-lasting intracellular storage. This study aimed to investigate the severity of intracellular storage of HES in renal tissue samples from critically ill dogs receiving 6% HES 130/0.4.Materials and Methods: Fresh, post-mortem (<2 h after death) renal tissue samples were analyzed through histology, immunohistochemistry (HES 130/0.4-specific antibodies), and electron microscopy for the severity of renal tubular vacuolization (VAC), intravacuolar HES accumulation (ACC), and ultra-structure impairment. Moreover, we investigated the relationship between VAC or ACC grade and HES dose (mL/kg), duration of HES administration (h), and pre-HES plasma creatinine concentrations.Results: Histology revealed that 2/20 dogs (10%) had no, 11/20 dogs (55%) had mild, 5/20 dogs (25%) had moderate, and 2/20 dogs (10%) had severe VAC. Immunohistochemistry revealed that 5/20 dogs (25%) had no, 6/20 dogs (30%) had mild, 7/20 dogs (35%) had moderate, and 2/20 dogs (10%) had severe ACC. Both changes were predominantly found in the distal tubular epithelium of mild and moderate cases, and all tubular segments were affected in severe cases. Seven of 20 dogs (35%) had osmotic nephrosis (ON). On electron microscopy, large granules with an electron-dense content were repeatedly detected in individual cells, mainly in the distal tubules. No correlation was found between cumulative HES dose or duration of HES administration and VAC grade, ACC grade, or presence/absence of ON.Conclusion: A high percentage of dogs had renal tubular HES storage and one-third of dogs showed HES-induced ON. Short-term HES administration caused VAC and ACC, regardless of the dose or duration of administration. In contrast to previous studies, HES 130/0.4 deposits were mainly located in the renal distal tubule.

Forensic Impact of the Omics Science Involved in the Wound: A Systematic Review

Background: In forensic autopsies, examining the wounds is one of the most critical aspects to clarify the causal relationship between the cause of death and the wounds observed on the corpse. However, on many occasions, it is difficult to differentiate antemortem injuries from post-mortem injuries, mainly when they occur very close to the moment of death. At present, various studies try to find biomarkers and clarify the molecular mechanisms involved in a wound due to the high variability of conditions in which they occur, thus being one of the most challenging problems in forensic pathology. This review aimed to study the omics data to determine the main lines of investigation emerging in the diagnosis of vital injuries, time of appearance, estimation of the age and vitality of the wound, and its possible contributions to the forensic field.Methods: A systematic review of the human wound concerning forensic science was carried out by following PRISMA guidelines.Results: This study sheds light on the role of omics research during the process of wounding, identifying different cytokines and other inflammatory mediators, as well as cells involved in the specific stage of the wound healing process, show great use in estimating the age of a wound. On the other hand, the expression levels of skin enzymes, proteins, metal ions, and other biomarkers play an essential role in differentiating vital and post-mortem wounds. More recent studies have begun to analyze and quantify mRNA from different genes that encode proteins that participate in the inflammation phase of a wound and miRNAs related to various cellular processes.Conclusions: This study sheds light on the role of research in the molecular characterization of vital wounds, heralding a promising future for molecular characterization of wounds in the field of forensic pathology, opening up an important new area of research.Systematic Review Registration: URL: https://www.crd.york.ac.uk/prospero/#myprospero, Identifier: CRD42021286623.

Fatal pulmonary tumour thrombotic microangiopathy in patient with ovarian adenocarcinoma: review and a case report

Background Pulmonary tumour thrombotic microangiopathy (PTTM) is a fatal disease in which tumour cells embolize to the pulmonary vasculature leading to pulmonary hypertension and right heart failure. Early diagnosis is essential for timely treatment which can reduce intimal pulmonary vascular proliferation and prolong survival, improve the symptoms. Due to rare occurrences and no clear diagnostic guidelines the disorder usually is found post-mortem. We present a review of this rare disease and a case of post-mortem diagnosed pulmonary tumour thrombotic microangiopathy in a young female. Case presentation 51 years old woman presented with progressively worsening dyspnea, right ventricular failure signs and symptoms. Computerized tomography denied pulmonary embolism. 2D transthoracic echocardiography demonstrated right ventricle dilatation and dysfunction, severely increased systolic pulmonary pressure. Right heart catheterization revealed pre-capillary pulmonary hypertension with mean pulmonary artery pressure of 78 mmHg, pulmonary wedge pressure of 15 mmHg, reduced cardiac output to 1.78 L/min with a calculated pulmonary vascular resistance of 35 Wood units, and extremely low oxygen saturation (26%) in pulmonary artery. Because of worsening ascites, pelvic magnetic resonance imaging was performed, tumours in both ovaries were diagnosed. Due to the high operative risk, detailed tumour diagnosis surgically was not established. The patient developed progressive cardiorespiratory failure, unresponsive to optimal heart failure drug treatment. A postmortem morphology analyses revealed tumorous masses in pre-capillary lung vessels, right ventricle hypertrophy, ovary adenocarcinoma. Conclusions An early diagnosis of PTTM is essential. Most cases are lethal due to respiratory failure progressing rapidly. Patients with a history of malignancy, symptoms and signs implying of PH should be considered of having PTTM. If detected early enough, combination of chemotherapy with specific PH therapy is believed to be beneficial in reducing intimal proliferation and prolonging survival, along with improving the symptoms.