The differential degradation of immature and mature bone in diverse environments: A controlled experiment using pig (Sus scrofa) skeletal remains

Several studies suggest that juvenile skeletal remains are significantly underrepresented in both forensic and archaeological excavations. In archaeological contexts, the disparities between historical burial records and the relative absence of juveniles in cemetery excavations have been a cause for much speculation. The most popular explanation for this paucity in the osteological record is a comparatively rapid breakdown of juvenile bones, due to their smaller size, incomplete mineralization, higher organic and water content, and higher porosity than their adult counterparts. If this holds true, it presents a challenge for accurately identifying skeletonized juveniles in forensic cases. While the idea is widely accepted, few experiments have provided evidence to support it. This study uses infant and sexually mature porcine models to explore the role of bone maturity with regards to: 1) overall susceptibility of the skeleton to biological, physical, and compositional degradation, and 2) the interaction of bone material with different burial environments. The ulnae of immature (2-8 weeks) and mature (6 months) pigs (Sus scrofa) were mechanically defleshed and used as a proxy for human bone of distinct infant and sexually mature groups. Samples (n=200) from both maturity groups were left to degrade in a climate-controlled greenhouse, either buried or on the soil surface. These two varying depositional conditions provide the degradation factors from two different environments. Every month, four bones from each maturity group and environment were collected. Weight loss on ignition analysis was performed on each sample to determine the relative water, collagen, and mineral composition of the bones, and bone weathering analysis was performed to quantify the physical changes of the bone surface. The results of this study indicate that, in the early postmortem interval, immature and mature bone material are differentially affected by their postmortem depositional environment. In both the subaerial and buried environments, the immature bone was found to be more susceptible to compositional degradation, while the mature bone was more heavily affected by physical weathering. It is not known how these initial differences in bone breakdown translate into the long-term survival of immature bone material, however, this study suggests that any interpretations of weathered immature bone, that are based on weathering rates determined by mature bone, should be done so with caution

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Medicine, Faculty ofNon UBCOrthopaedic Surgery, Department ofReviewedFacultyResearcherOthe

Characterization of the gut microbiome in a porcine model of thoracic spinal cord injury

Background The gut microbiome is a diverse network of bacteria which inhabit our digestive tract and is crucial for efficient cellular metabolism, nutrient absorption, and immune system development. Spinal cord injury (SCI) disrupts autonomic function below the level of injury and can alter the composition of the gut microbiome. Studies in rodent models have shown that SCI-induced bacterial imbalances in the gut can exacerbate the spinal cord damage and impair recovery. In this study we, for the first time, characterized the composition of the gut microbiome in a Yucatan minipig SCI model. We compared the relative abundance of the most dominant bacterial phyla in control samples to those collected from animals who underwent a contusion-compression SCI at the 2nd or 10th Thoracic level. Results We identify specific bacterial fluctuations that are unique to SCI animals, which were not found in uninjured animals given the same dietary regimen or antibiotic administration. Further, we identified a specific time-frame, “SCI-acute stage”, during which many of these bacterial fluctuations occur before returning to “baseline” levels. Conclusion This work presents a dynamic view of the microbiome changes that accompany SCI, establishes a resource for future studies and to understand the changes that occur to gut microbiota after spinal cord injury and may point to a potential therapeutic target for future treatment.Medicine, Faculty ofOther UBCOrthopaedic Surgery, Department ofReviewedFacultyResearcherOthe

Cardio-centric hemodynamic management improves spinal cord oxygenation and mitigates hemorrhage in acute spinal cord injury

Clinical neuroprotective strategies for acute spinal cord injury (SCI) have largely overlooked the heart. Here the authors show cardiac contractility is immediately impaired in a porcine model of T2 SCI, and cardio-centric treatment with dobutamine optimizes cord oxygenation and mitigates haemorrhage