A Black (and Rising?) Tide: Controlling Maritime Oil Pollution in Canada

A series of dramatic oil spills in recent years has once again drawn critical attention to the nature and adequacy of existing domestic and international legislation regarding ship source oil pollution. Predictably, legislators and policy makers have responded with a plethora of studies, reviews, and consultations. However, past improvements to the domestic and international regimes have traditionally been slow and incremental, at best. In Canada, approximately three years have passed since the Nestucca spill took place off the B.C. coast. Yet, while there has been much discussion, domestic legislation remains virtually unaltered at the present time. The authors find that the status quo must be changed substantially, in order for real and significant improvement in marine environmental protection to be achieved. Mere tinkering with the existing regime has proved to be largely ineffective

Sex, selfish genes, and the shared genome

Sexual conflict can occur whenever the evolutionary interests of males and females differ, and when sexually antagonistic selection acts upon traits shared between the sexes, one or both sexes can be constrained from reaching their phenotypic optima. This intralocus sexual conflict can be characterised by a tug-of-war of allelic replacement until it is resolved, but examples of well-characterised sexually antagonistic loci are rare. This thesis investigates the basis and dynamics of intralocus sexual conflict over insecticide resistance at the Cyp6g1 locus in Drosophila melanogaster, and wing colouration in Drosophila simulans. In D. melanogaster, the Cyp6g1 locus is the site of a series of insecticide resistance alleles, one of which is sexually antagonistic when back-crossed to the old isogenic lab strain Canton-S. I investigated the presence of sexual conflict over this same allele in a recently collected and genetically heterogeneous population. I found evidence of balancing selection on resistance (Ch. 2) that could not be explained by overdominance or sex-specific dominance (Ch. 3). However, balancing selection could be explained by resistance conferring increased fecundity to females (Ch. 2-4), and decreased reproductive success to males (Ch. 4). This male cost can in turn be explained by a negative genetic correlation between reproductive success and Cyp6g1 expression (Ch. 4), possibly influencing levels of reproductive investment (Ch. 2). Additionally, I explored the dynamics of the sex-specific fitness effects of resistance across three Cyp6g1 alleles back-crossed to a single genetic background. I found no evidence of sexual antagonism, but revealed that the cost of resistance increased with more derived alleles, and that all alleles were more costly to females (Ch. 5). After decades of strong selection imposed by insecticide use an unresolved sexual conflict persists at the Cyp6g1 locus despite sexual dimorphism in resistance, and it does not appear that more derived Cyp6g1 alleles are necessarily involved in mediating this conflict. Wing interference patterns (WIPs) are a newly discovered trait subject to female mate choice in Drosophila. I explored the potential for intralocus sexual conflict over WIPs by measuring WIP traits from males and females from populations of D. simulans evolved under relaxed or elevated sexual selection. In response to sexual selection male WIPs evolved to be brighter, higher contrast, and shifted to longer wavelengths of light, but there was no associated response to selection in females (Ch. 6). While WIPs did not appear to be constrained from detectably responding to selection by acute intralocus sexual conflict, male WIPs from the relaxed selection regime were similar to female WIPs, suggesting a cost to sexually selected WIPs that may be indicative of sexually antagonistic selection. IASC is pervasive and can influence a wide range of fundamental evolutionary processes including sexual selection, speciation, and extinction. The research presented in this thesis adds to a body of evidence that sexual dimorphism does not necessarily resolve IASC, and documents the first evidence that WIPs do not appear to be subject to acute IASC and can evolve in response to sexual selection.BBSR

WCN24-931 AKI Phenotypes in Ugandan children hospitalized with Hypoxemia and Malaria

Introduction: Acute kidney injury (AKI) is a frequent life-threatening complication in hospitalized children. Emerging data suggest AKI is a heterogeneous condition that varies based on the underlying cause and is composed of distinct phenotypes. The objective of this study was to define AKI phenotypes using proposed classification systems in Ugandan children hospitalized with hypoxemia and to evaluate differences in phenotypes by malaria infection. Methods: Between 2019 and 2021, 2402 Ugandan children \u3c5 years of age hospitalized with hypoxemia were enrolled in a cluster randomized trial of solar powered oxygen delivery across 20 districts in Uganda. At enrollment, urine NGAL was measured using a point-of-care lateral flow test with a positive test defined as a level ≥150ng/mL. Malaria was assessed using a threeband rapid diagnostic test. In an extended sub-study, 491 children had creatinine measured to define AKI. AKI was defined using a single creatinine measure at enrolment and phenotypically characterized using two acute dialysis quality initiative (ADQI) proposed AKI phenotypes. The AKI biomarker definition incorporated urine NGAL into the KDIGO definition[group 1, no AKI; group 2, subclinical AKI (biomarker positive); group 3, AKI; group 4, biomarker positive AKI]. The ADQI sepsis AKI phenotype groups stage 1 AKI as sepsis phenotype (SP)-1 irrespective of biomarker status and differentiates severe AKI (stage 2/3) based on biomarker positivity where severe AKI that is biomarker negative is (SP2) and severe biomarker positive AKI is SP3. Results: Overall, 491 children were included in the extended study with AKI defined and uNGAL measured. The median age was 1.3 years (interquartile range, 0.7 to 2.3) and 53.8% of children were male. There were 4 deaths (0.8%) and 24 children required transfer to a higher-level health facility (4.9%). Among children included, 91.2% met a clinical definition of pneumonia and 49.5% were positive for malaria. The frequency of creatinine defined AKI was 32.0% (157/491) and 36.5% (179/491) were biomarker positive. AKI was associated with a 3.24-fold increase in mortality (95% CI 0.34 to 31.4) but underpowered to show a difference. In children without malaria, 17.7% were biomarker positive and AKI negative (subclinical AKI, 44/248) while 37.5% of children had AKI (93/284) of whom 39.8% (37/93) were biomarker positive. In children with malaria, 14.0% had subclinical AKI, 34/243), 59.3% had AKI (144/243) with 44.4% of AKI cases biomarker positive (64/144). Children with malaria had a higher frequency of AKI compared to children without malaria (59.6% vs. 37.6%, p\u3c0.001) but comparable frequency of a positive biomarker test (41.3% vs. 36.2%, p=0.10). Using the sepsis phenotype criteria, 16.3% of children had SP1, 17.9% were SP2 and 14.1% were SP3. When evaluating the sepsis phenotype by malaria status, children with malaria were more likely to have SP2 (23.1% vs. 12.9%) and SP3 (18.1% vs.10.1%) compared to children without malaria (p\u3c0.001). Conclusions: In this population of children hospitalized with hypoxemia across 20 health centers in Uganda, KDIGO-defined AKI was more common in children with malaria. While there was no difference in the AKI-biomarker classification based on malaria status, children with malaria were more likely to have severe phenotypes of AKI

Pediatric Malaria with Respiratory Distress: Prognostic Significance of Point-of-Care Lactate

Respiratory distress (RD) in pediatric malaria portends a grave prognosis. Lactic acidosis is a biomarker of severe disease. We investigated whether lactate, measured at admission using a handheld device among children hospitalized with malaria and RD, was predictive of subsequent mortality. We performed a pooled analysis of Ugandan children under five years of age hospitalized with malaria and RD from three past studies. In total, 1324 children with malaria and RD (median age 1.4 years, 46% female) from 21 health facilities were included. Median lactate level at admission was 4.6 mmol/L (IQR 2.6–8.5) and 586 patients (44%) had hyperlactatemia (lactate \u3e 5 mmol/L). The mortality was 84/1324 (6.3%). In a mixed-effects Cox proportional hazard model adjusting for age, sex, clinical severity score (fixed effects), study, and site (random effects), hyperlactatemia was associated with a 3-fold increased hazard of death (aHR 3.0, 95%CI 1.8–5.3, p \u3c 0.0001). Delayed capillary refill time (τ = 0.14, p \u3c 0.0001), hypotension (τ = −0.10, p = 0.00049), anemia (τ = −0.25, p \u3c 0.0001), low tissue oxygen delivery (τ = −0.19, p \u3c 0.0001), high parasite density (τ = 0.10, p \u3c 0.0001), and acute kidney injury (p = 0.00047) were associated with higher lactate levels. In children with malaria and RD, bedside lactate may be a useful triage tool, predictive of mortality

WCN24-2067 Regional differences in acute kidney injury in Ugandan children hospitalized for Hypoxemia

Introduction: Acute kidney injury (AKI) is associated with increased mortality in hospitalized patients and incidence is highest in resource limited settings. The objective of this study was to assess sub-National regional differences in the incidence of AKI in children \u3c5 years of age hospitalized with an acute febrile illness and hypoxemia. Methods: This was a secondary analysis of a stepped wedge cluster randomized controlled trial, which enrolled children \u3c5 years of age hospitalized with hypoxemia between 2019 and 2021. At least one measure of kidney function was available in 1452 children. A single creatinine was measured at enrolment in a sub-set of 495 children with serum stored and AKI defined using KDIGO criteria where baseline creatinine was estimated using the age-based Pottel equation assuming a normal glomerular filtration rate of 120mL/min per 1.73m2. Markers were divided into structural (uNGAL positive, proteinuria, hematuria) or functional (AKI, saliva urea nitrogen (SUN)) measures of kidney injury. Results: 1452 children were included in this AKI sub-study (Figure 1). The mean age of participants was 1.49 years (standard deviation (SD), 1.21) and 55.7% were male (809/1452). Overall 2.6% of children died (38/1452). The majority of participants enrolled were from the West (31.3%) followed by the East (25.3%), North (24.1%), and Central (19.4%) regions. In general, 48.5% of children had AKI (240/495), the prevalence was highest in Eastern Uganda with 62.4% of children having AKI compared to 25.0% of children in Western Uganda, 44% in Central region and 53% in Northern region (p\u3c0.001). Over a third of children had urine NGAL levels ≥150ng/mL, a marker of structural damage, irrespective of site and rates comparable across sites (p=0.095). Other measures of functional and structural kidney injury varied across sites, proteinuria ranged from 6.3% to 14.0% with rates lower in Central and Eastern Uganda compared to Northern and Western Uganda. Hematuria was over two times more common in Eastern and Northern Uganda compared to Central and Western Uganda. Of all the children 49.0 % were positive for malaria based on rapid diagnostic test (RDT) either as positive pLDH or both pLDH and HRP-2. The presence of a single band positive RDT for HRP-2 alone was associated with increased risk of AKI, severe AKI, elevated BUN, a positive SUN test and urinalysis positive for hematuria or urobilinogen (unadjusted p\u3c0.05). Children with a 3-band positive RDT were more likely to have proteinuria, hematuria, bilirubinuria and urobilinogen by dipstick (unadjusted p\u3c0.05). Regional differences in AKI persisted after adjusting for malaria, age, and sex. Conclusions: As we move towards the ISN 0by25 initiative which aims to eliminate preventable deaths from AKI worldwide by 2025. This study provides key in-country data from a resource limited setting, demonstrating marked regional differences in the incidence of AKI in children hospitalized with hypoxaemia and malaria remains an important predictor of AKI. The substantial within-country heterogeneity of AKI highlights the need for further studies to evaluate regional contributors to local patterns of AKI

Validation of two multiplex platforms to quantify circulating markers of inflammation and endothelial injury in severe infection

Biomarkers can prognosticate outcome and enable risk-stratification. In severe infection, focusing on multiple markers reflecting pathophysiological mechanisms of organ injury could enhance management and pathway-directed therapeutics. Limited data exist on the performance of multiplex biomarker platforms. Our goal was to compare endothelial and immune activation biomarkers in severe pediatric infections using two multiplex platforms. Frozen plasma from 410 children presenting to the Jinja Regional Hospital in Uganda with suspected infection was used to measure biomarkers of endothelial (Angiopoietin-2, sFlt-1, sVCAM-1, sICAM-1) and immune (IL-6, IP-10, sTNFR-1, CHI3L1) activation. Two multiplex platforms (Luminex®, EllaTM) based on monoclonal antibody sandwich immunoassays using biotin-streptavidin conjugate chemistry were selected with reagents from R&D Systems. The two platforms differed in ease and time of completion, number of samples per assay, and dynamic concentration range. Intra-assay variability assessed using a coefficient of variation (CV%) was 2.2-3.4 for Luminex® and 1.2-2.9 for EllaTM. Correlations for biomarker concentrations within dynamic range of both platforms were best for IL-6 (ρ = 0.96, p<0.0001), IP-10 (ρ = 0.94, p<0.0001) and sFlt-1 (ρ = 0.94, p<0.0001). Agreement between concentrations obtained by both methods assessed by the Bland-Altman test varied, with best agreement for CHI3L1. Our data suggest that biomarkers of endothelial and immune activation can be readily measured with multiplex platforms. Luminex® and EllaTM produced reliable results with excellent CV% values. The EllaTM platform was more automated and completed in 75 minutes, potentially compatible with near-patient use. Trends in concentrations obtained by these methods were highly correlated, although absolute values varied, suggesting caution is required when comparing data from different multiplex platforms

Fas (CD95) induces rapid, TLR4/IRAK4-dependent release of pro-inflammatory HMGB1 from macrophages

Although Fas (CD95) is recognized as a death receptor that induces apoptosis, recent studies indicate that the Fas/FasL system can induce pro-inflammatory cytokine production by macrophages independent of conventional caspase-mediated apoptotic signaling. The precise mechanism(s) by which Fas activates macrophage inflammation is unknown. We hypothesized that Fas stimulates rapid release of high mobility group box 1 (HMGB1) that acts in an autocrine and/or paracrine manner to stimulate pro-inflammatory cytokine production via a Toll-like receptor-4 (TLR4)/Interleukin-1 receptor associated kinase-4 (IRAK4)-dependent mechanism. Following Fas activation, HMGB1 was released within 1 hr from viable RAW267.4 cells and primary murine peritoneal macrophages. HMGB1 release was more rapid following Fas activation compared to LPS stimulation. Neutralization of HMGB1 with an inhibitory anti-HMGB1 monoclonal antibody strongly inhibited Fas-induced production of tumor necrosis factor (TNF) and macrophage inflammatory protein-2 (MIP-2). Both Fas-induced HMGB1 release and associated pro-inflammatory cytokine production were significantly decreased from Tlr4-/- and Irak4-/- macrophages, but not Tlr2-/- macrophages. These findings reveal a novel mechanism underlying Fas-mediated pro-inflammatory physiological responses in macrophages. We conclude that Fas activation induces rapid, TLR4/IRAK4-dependent release of HMGB1 that contributes to Fas-mediated pro-inflammatory cytokine production by viable macrophages

Modeling, Reduction, and Control of a Helically Actuated Inertial Soft Robotic Arm via the Koopman Operator

Soft robots promise improved safety and capability over rigid robots when deployed in complex, delicate, and dynamic environments. However, the infinite degrees of freedom and highly nonlinear dynamics of these systems severely complicate their modeling and control. As a step toward addressing this open challenge, we apply the data-driven, Hankel Dynamic Mode Decomposition (HDMD) with time delay observables to the model identification of a highly inertial, helical soft robotic arm with a high number of underactuated degrees of freedom. The resulting model is linear and hence amenable to control via a Linear Quadratic Regulator (LQR). Using our test bed device, a dynamic, lightweight pneumatic fabric arm with an inertial mass at the tip, we show that the combination of HDMD and LQR allows us to command our robot to achieve arbitrary poses using only open loop control. We further show that Koopman spectral analysis gives us a dimensionally reduced basis of modes which decreases computational complexity without sacrificing predictive power.Comment: Submitted to IEEE International Conference on Robotics and Automation, 202

Accidental Drop of a Carbon Steel/Lead Shipping Cask (HFEF 14) at Low Temperatures

A shielded cask is used to transport radioactive materials between facilities at the Idaho National Laboratory. The cask was fabricated with an outer and inner shell of A36 carbon steel with lead poured in the annular space between the shells to provide radiation shielding. Carbon steel is known to be susceptible to low-temperature brittle fracture under impact loading. This paper will present the analysis results representing postulated transportation accidents during on-site transfers of the cask at subzero temperatures. The accident scenarios were based on a series of cask drops onto a rigid surface from a height of 1.83m (6 ft.) Finite element models of the cask and its contents were solved and post processed using the ABAQUS software. Each model was examined for failure to contain radioactive materials and/or significant loss of radiation shielding. Results of these analyses show that the body of the cask exhibits considerable ruggedness and will remain largely intact after the impact. There will be deformation of the main cask body with localized brittle failure of the cask outer shell and door structure. The cask payload outer waste can remains in the cask but will experience some permanent plastic deformation in each drop. It will not be deformed to the point where it will rupture, thus maintaining confinement of the can contents