Post-COVID-19 Thoracic Aortic Rupture with an Unforeseen Spinal Epidural Hematoma.

The importance of prompt diagnosis and early stenting of an aortic rupture cannot be overemphasized. We present a case of thoracic aortic rupture in a middle-aged gentleman who had recently suffered coronavirus disease 2019. The case was further complicated by the development of an unexpected spinal epidural hematoma.

Fragmentation by major dams and implications for the future viability of platypus populations.

The evolutionarily unique platypus (Ornithorhynchus anatinus) has experienced major declines and extinctions from a range of historical and recent interacting human-mediated threats. Although spending most of their time in the water, platypuses can move over land. Nevertheless, uncertainties remain whether dams are barriers to movement, thus limiting gene flow and dispersal, essential to evolution and ecology. Here we examined disruption of gene flow between platypus groups below and above five major dams, matched to four adjacent rivers without major dams. Genetic differentiation (FST) across dams was 4- to 20-fold higher than along similar stretches of adjacent undammed rivers; FST across dams was similar to differentiation between adjacent river systems. This indicates that major dams represent major barriers for platypus movements. Furthermore, FST between groups was correlated with the year in which the dam was built, increasing by 0.011 every generation, reflecting the effects of these barriers on platypus genetics. This study provides evidence of gene flow restriction, which jeopardises the long-term viability of platypus populations when groups are fragmented by major dams. Mitigation strategies, such as building of by-pass structures and translocation between upstream and downstream of the dam, should be considered in conservation and management planning.

Extracranial Internal Carotid Artery Aneurysm in Pregnancy.

Isolated extracranial internal carotid artery aneurysms (EICAAs) are rare, accounting for only about .4-4% of all peripheral artery aneurysms. We present a case of an EICAA in a young pregnant patient. To our knowledge, this is the first case being reported of a true EICAA during pregnancy in a multiparous woman. A 25-year-old pregnant patient presented with a pulsatile left neck swelling. Radiological investigations and subsequent surgery during the first trimester confirmed a true saccular left ICA with a maximum diameter of 3.5 cm. She was treated with aneurysm excision and primary anastomosis. She did not have any underlying diseases predisposing to an EICAA. She has been well for 3 years post procedure. It has been postulated that pregnancy could lead to aneurysm development through multiple mechanisms, including hemodynamic, hormonal, and other physiologic changes of pregnancy. Aggressive treatment with surgical intervention is advocated because of the risk of cerebral ischemic complications associated with non-operative treatment, and because satisfactory long-term outcomes can be achieved from surgery.

Emergent behavior in an adversarial synchronization and swarming model.

We consider a red-versus-blue coupled synchronization and spatial swarming (i.e., swarmalator) model that incorporates attraction and repulsion terms and an adversarial game of phases. The model exhibits behaviors such as spontaneous emergence of tactical manoeuvres of envelopment (e.g., flanking, pincer, and envelopment) that are often proposed in military theory or observed in nature. We classify these states based on a large set of features such as spatial densities, synchronization between clusters, and measures of cluster distances. These features are used to study the influence of coupling parameters on the expected presence of these states and the-sometimes sharp-transitions between them.

Impact of Harvesting on a Bioeconomic Predator-Prey Fishery Model Subject to Environmental Toxicant.

The present paper studies a predator-prey fishery model which incorporates the independent harvesting strategies and nonlinear impact of an anthropogenic toxicant. Both fish populations are harvested with different harvesting efforts, and the cases for the presence and non-presence of harvesting effort are discussed. The prey fish population is assumed to be infected by the toxicant directly which causes indirect infection to predator fish population through the feeding process. Each equilibrium of the proposed system is examined by analyzing the respective local stability properties. Dynamical behavior and bifurcations are studied with the assistance of threshold conditions influencing the persistence and extinction of both predator and prey. Bionomic equilibrium solutions for three possible cases are investigated with certain restrictions. Optimal harvesting policy is explored by utilizing the Pontryagin's Maximum Principle to optimize the profit while maintaining the sustainability of the marine ecosystem. Bifurcation analysis showed that the harvesting parameters are the key elements causing fishery extinction. Numerical simulations of bionomic and optimal equilibrium solutions showed that the presence of toxicant has a detrimental effect on the fish populations.

Endovascular treatment of cephalic arch stenosis in brachiocephalic arteriovenous fistulas: A systematic review and meta-analysis.

PURPOSE: The aim of this study is to appraise the current literature on the endovascular management options and their outcomes of cephalic arch stenosis in the setting of a failing brachiocephalic fistula for hemodialysis. METHODS: A systematic search of the literature was performed using PubMed, Embase, and Google Scholar from January 2000 to December 2017 in accordance with the PRISMA guidelines to investigate the outcomes of endovascular management of cephalic arch stenosis. Data from randomized controlled trials and observational studies, published in the English language, were extracted to determine pooled proportion of primary and secondary patency, using a random-effects meta-analysis. Subgroup analyses of stent grafts, bare metal stents, and percutaneous transluminal angioplasty outcomes were performed. RESULTS: Of the 125 total studies, 11 were included for analysis by consensus. Overall, 457 patients were reviewed and analyzed for primary and secondary patency rates at 6 and 12 months post-treatment. There was significantly higher primary patency at both 6 and 12 months in the stent graft group compared to those who received bare metal stents or percutaneous transluminal angioplasty (relative risk = 0.30-0.31, relative risk = 0.34-0.59, respectively; p < 0.01). Higher secondary patency rates were noted in the bare metal stents cohort compared to the percutaneous transluminal angioplasty cohort at 12 months (relative risk = 0.17, 95% confidence interval = 0.07-0.26; p < 0.01). CONCLUSION: This study demonstrated a significant benefit in using stent grafts in cephalic arch stenosis compared to bare metal stents or percutaneous transluminal angioplasty with higher primary and secondary patency rates.

Zoonotic Transmission of Waterborne Disease: A Mathematical Model.

Waterborne parasites that infect both humans and animals are common causes of diarrhoeal illness, but the relative importance of transmission between humans and animals and vice versa remains poorly understood. Transmission of infection from animals to humans via environmental reservoirs, such as water sources, has attracted attention as a potential source of endemic and epidemic infections, but existing mathematical models of waterborne disease transmission have limitations for studying this phenomenon, as they only consider contamination of environmental reservoirs by humans. This paper develops a mathematical model that represents the transmission of waterborne parasites within and between both animal and human populations. It also improves upon existing models by including animal contamination of water sources explicitly. Linear stability analysis and simulation results, using realistic parameter values to describe Giardia transmission in rural Australia, show that endemic infection of an animal host with zoonotic protozoa can result in endemic infection in human hosts, even in the absence of person-to-person transmission. These results imply that zoonotic transmission via environmental reservoirs is important.

Limb salvage in patients with peripheral arterial disease managed by endovascular first approach.

This study aims to review the outcome of patients with peripheral arterial disease (PAD) managed with endovascular first approach for revascularization in a tertiary referral center. Revascularization procedures were performed in 202 patients with 229 symptomatic limbs. Angiogram was performed in all patients except those contraindicated for contrast agent. Angioplasty revascularization was carried out on the same setting whenever feasible based on the angiogram findings. Bypass surgery was performed in patients with arterial condition not feasible for endovascular intervention or in those with unsatisfactory revascularization after endovascular treatment. Endovascular intervention was successfully performed in 198 limbs. Bypass surgery was required in 31 patients. Another 16 patients required a bypass after endovascular intervention due to unsatisfactory wound healing. The Kaplan-Meier estimated survival and amputation-free survival were 80% and 75.5% at 1 year and 73% and 57.6% at 2 years, respectively. Satisfactory limb salvage rate can be achieved in patients with PAD managed with endovascular first approach.

Spontaneous inferior epigastric artery pseudoaneurysm.

A case of spontaneous pseudoaneurysm of the inferior epigastric artery-diagnosed on Doppler sonography-is presented. A 19-year-old boy presented with a lump in the anterior abdominal wall. Clinically a smooth, nontender, and noncompressible mass was present above umbilicus to the right of midline. A bruit was heard over the swelling. Doppler sonography demonstrated an oval hypoechoic structure in the right rectus sheath with turbulent flow. The pseudoaneurysm could be traced to the inferior epigastric artery. Surgical excision of pseudoaneurysm was performed. Histopathology showed myxoid changes in the wall of the pseudoaneurysm with no inflammatory changes.

Host gastro-intestinal dynamics and the frequency of colicin production by Escherichia coli.

The production of antimicrobial compounds known as colicins has been shown to be an important mediator of competitive interactions among Escherichia coli genotypes. There is some understanding of the forces responsible for determining the frequency of colicin production in E. coli populations; however, this understanding cannot explain all of the observed variation. A survey of colicin production in E. coli isolated from native Australian mammals revealed that the frequency of colicin production in strains isolated from carnivores was significantly lower than the frequency of production in strains recovered from herbivores or omnivores. The intestine of Australian carnivores is tube-like and gut turnover rates are rapid compared with the turnover rates of the intestinal tracts of herbivores and omnivores, all of which possess a hindgut fermentation chamber. A mathematical model was developed in order to determine if variation in gut turnover rates could determine if a host was more likely to harbour a colicin-producing strain or a non-producer. The model predicted that a colicin producer was more likely to dominate in the gut of a host with lower gut turnover rates, and a non-producer to dominate in hosts with rapid gut turnover rates.

Plant-herbivore models, where more grass means fewer grazers.

Classical theory has led us to believe that where more grazing is available herbivores will inflict heavier pressure on the grass, thus keeping its height low. This approach is hotly debated, although still widely accepted. Based on field data collected, van der Koppel et al. [van der Koppel, J., Huisman, J., van der Wal, R., Olff, H., 1996. Patterns of herbivory along a productivity gradient: an empirical and theoretical investigation. Ecology 77, 736-745] contest the standard plant-herbivore models, arguing that herbivores do not 'control' the plant growth entirely, and propose two differential equation models. In this paper we describe briefly how van der Koppel et al. (1996) derive their uncontrolled plant-herbivore interaction models, and then expand on the specific mathematical results cited in their paper to provide a global overview of the dynamics of such systems, for a broad range of parameter values.