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Review of “The Madman and the Butcher” by Tim Cook
No full textReview of The Madman and the Butcher by Tim Coo
Review of “Turning Back the Fenians: New Brunswick’s Last Colonial Campaign” by Robert L. Dallison
No full textReview of Turning Back the Fenians: New Brunswick’s Last Colonial Campaign by Robert L. Dalliso
Review of “The Canadian Iroquois and the Seven Years’ War” by D. Peter MacLeod
No full textReview of The Canadian Iroquois and the Seven Years’ War by D. Peter MacLeo
Nanoparticle carriers enhance the prophylactic antiviral effects of dsRNA in vitro and ex vivo
No full textAquaculture now outpaces traditional capture fisheries as the world population and demand for sustainable protein sources increases. Wild and farmed species are increasingly susceptible to pathogen spread as global temperatures rise and stocking densities increase. Despite the devastating losses experienced by aquaculture due to viral infections, there remain few effective prophylactic antiviral therapeutics. Long double-stranded (ds)RNA is a uniquely viral molecule produced by nearly all viruses during their replication cycle, and its detection by salmonids like rainbow trout (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytsha) leads to the establishment of a defensive antiviral state. Previous in vitro studies demonstrated a reduction in the severity of viral infections following prophylactic treatment by long dsRNA delivered by nanoparticles). This dissertation determined that: i) the toxicity imparted by cationic stearylamine liposomes outweighed their protective capabilities in vitro, ii) phytoglycogen nanoparticles enhanced the antiviral protection of HMW poly I:C in vitro, iii) HMW poly I:C delivered by phytoglycogen nanoparticles enhanced peripheral blood leukocyte phagocytosis, antiviral gene expression, and metabolism ex vivo while also inducing antiviral gene expression in ex vivo intestine models, and iv) the loss of the cytosolic PRR MDA5 decreased the responsiveness of chinook salmon embryonic cells to dsRNA over 500bp and increased susceptibility to viral infection. Together, this foundational knowledge can direct further investigations into the potential of nanocarriers to enhance antiviral protection in vivo. to protect the growing aquaculture industry against significant losses from viral infections and inform disease management strategies in wild populations
Adapting to Uncertainty: Effects of Environmental Instability on Zebrafish Behaviour
No full textThis thesis addresses how animals cope with unpredictability by testing how environmental stability changes the behaviour of zebrafish (Danio rerio) in two complementary experiments. In Experiment 1, fish lived for three months in either a Dynamic environment (water temperature, feeding times, habitat complexity, group size, and membership fluctuated) or a Stable environment (all factors constant). Across seven behavioural assays, measuring individual behavioural differences, collective movement, social memory, and information use, Dynamic condition fish were found to be more sensitive to social cues and more likely to conform to recent social information, independent of the quality of the information itself. They also maintained social motivation and swam closer together, but were less coordinated in shoals. These results suggest that when conditions change frequently, older information degrades quickly, while recent information becomes more valuable. Social stimuli may also become more salient because social information allows for faster updating in changing conditions.
In Experiment 2, to test whether social stability drove these effects, I isolated group membership and manipulated group phenotypic composition. Fish were housed in either a stable homogeneous group (similar personalities), a stable heterogeneous group (mixed personalities), or in groups with membership that changed every other day. Extending three assays from Experiment 1, I examined consistent individual behavioural differences (personality) and collective movement while controlling for familiarity. Fish from dynamic social environments increased the most in boldness and decreased the most in sociability (contrary to Experiment 1), and were the most repeatable in both traits, becoming the most extreme and rigid in personality, likely because continuous role-shifting is costly. Fish from the Dynamic condition were again closer together and less coordinated in shoals than those from one of the Stable conditions (similar to Experiment 1), independent of familiarity, showing that social instability alone can disrupt schooling in fish. Shoals composed of bolder fish were also more coordinated. Lastly, living in heterogeneous groups pushed for conformity, while homogeneous groups did not change meaningfully in either trait.
In rapidly changing environments, information quickly becomes outdated, and conspecifics provide the most recent information. This thesis shows that zebrafish adjust their decision-making strategies and both individual and collective behaviour to adapt to unpredictable conditions, offering insight into the mechanisms and possibly implications of behavioural plasticity in an increasingly unpredictable world
Neural Correlates of Cognitive Fatigue in Regular Cannabis Users and Non-users: A Pilot fNIRS Study
No full textBackground: Cognitive fatigue impairs performance across multiple domains, yet how regular cannabis use affects fatigue responses remains unclear. This pilot study investigated neural and behavioural correlates of cognitive fatigue in abstinent cannabis users versus non-users.
Methods: Twenty-six participants (18 non-users, 8 regular cannabis users after 24-hour abstinence) completed cognitive tasks before and after a 60-minute Sustained Attention to Response Task (SART) designed to induce fatigue. Tasks assessed working memory (N-Back), cognitive flexibility (Wisconsin Card Sorting), psychomotor speed (Digit Symbol Substitution), sustained attention (Continuous Performance Task), inhibition (Stroop, Stop Signal), and motion perception. Functional near-infrared spectroscopy (fNIRS) continuously monitored prefrontal cortex activation across 20 channels organized into 7 regions of interest.
Results: Both groups reported increased subjective fatigue (VAS-F) post-SART. Behaviourally, most cognitive tasks showed practice effects rather than fatigue-related decrements. FNIRS revealed divergent patterns: non-users showed increased prefrontal HbO values post-SART (110% increase), while cannabis users showed decreased HbO values (shifting from positive to negative). Effect sizes for group differences were medium to large for several tasks (Stroop, d = -0.58; Digit Symbol, d = -0.55; CPT, d = -0.50) despite not reaching statistical significance due to limited power.
Conclusions: This exploratory study suggests abstinent cannabis users and non-users show opposing neural adaptation patterns to cognitive fatigue. While underpowered for definitive conclusions, the divergent hemodynamic responses warrant investigation with larger samples to understand how cannabis use history affects fatigue vulnerability.
Keywords: Cognitive fatigue, mental fatigue, sustained attention, cannabis, fNIRS, neuroimaging, prefrontal cortex, motion coherence, pilot stud
The disruption of gastrointestinal hormonal control of digestion in Nile tilapia by omeprazole
No full textStomach acidity is a critical feature of the digestive system, facilitating the breakdown of protein through the activation of the protease pepsin. Gastric acid is secreted by H+/K+ ATPase, the gastric proton pump. A previous study on Nile tilapia (Oreochromis niloticus) showed that inhibiting the production of stomach acid using the proton pump inhibitor omeprazole (omz), reduced growth that correlated with an acceleration of the rate of gastric emptying. This contrasts with omz exposure studies in mammals in which there is a delay in gastric emptying and no impact on growth. To understand the mechanism behind rapid rates of gastric emptying in tilapia; the role of cholecystokinin (CCK) was examined in this study. CCK controls the rate of gastric motility as it contracts the most anterior part of the intestine to delay gastric emptying, holding food so that it can correctly go through the digestive process. Post-prandial changes in tilapia fed a fixed ration of 2% body mass day-1 of pellets either with (25mg kg-1 d-1) omeprazole or without was examined. Omeprazole treatment replicated the decrease in gastric acid secretion (88-94%), increased gastric emptying and decreased specific growth rate (30%) previously observed. Significantly, it lowered circulating plasma CCK concentrations and lowered cck gene expression in the anterior intestine as well as cckb receptor (cckbr) levels in the stomach, which is associated with the binding of the CCK hormone and gastrin (responsible for stimulating gastric acid secretion and motility) hormone that stimulates acid secretion. Together these results suggest a reduced release of CCK that would explain the accelerated rate of stomach emptying seen in tilapia. The expression of additional genes was looked at to determine the differences between omz vs sham treatments. While the expression of growth hormone and pepsinogen genes showed statistically significant differences, other genes showed no differences. A feeding trial was conducted to observe whether fish on an omeprazole diet could compensate for their reduced growth with an increase in appetite and food intake. Instead, there was no increase in food intake in omeprazole fed fish compared to the sham, with no difference in expression of genes for hunger at the transcriptional level. My study observed the interactions of gastric acidification and its relationship to the endocrine system on a molecular level not only with CCK but other hormones and genes that are influenced by gastric acidification, bridging the gap in knowledge between the interaction of the endocrine systems with the stomach in a teleost species
Impact of exercise intensity and duration on metabolism during and post-exercise
No full textAbstract
INTRODUCTION: A common low-volume high-intensity interval training (HIIT) protocol involves repeating 1-min near-maximal bouts interspersed with 1-min rest 10 times within a session and has demonstrated greater excess post-exercise oxygen consumption (EPOC) than moderate-intensity continuous training (MICT). While typical MICT protocols (≥30 min) are longer than low-volume HIIT (20 min), yielding greater oxygen consumed (VO2) during exercise, higher-volume HIIT protocols of similar duration to MICT (≥28 min) have been shown to elicit similar during-exercise VO2 while eliciting greater EPOC. PURPOSE: To examine effects of extending the 20-min low-volume HIIT protocol to 30 min (by adding 5 additional exercise bouts) on overall VO2 and post-exercise fat oxidation compared to MICT. METHODS: Nine recreationally active males (age: 22±4 y, V̇O2max: 48.2±7.6 ml⋅kg-1⋅min-1, HRmax: 193±8 bpm) completed four randomized sessions: (1) no-exercise control (CTRL); (2) MICT (30 min at 60% VO2max); (3) low-volume HIIT (10x1-min at 90% HRmax, 1-min rest); and (4) higher-volume HIIT (15x1-min at 90% HRmax, 1-min rest). Between-session differences for overall VO2 and fat oxidation were assessed. RESULTS: V̇O2 during exercise was elevated in all exercise sessions versus CTRL (P\u3c 0.001). Overall session O2 consumed was greater in all exercise sessions (MICT: 116.2±11.6 L; low-volume HIIT: 101.6±11.5 L; higher-volume HIIT: 126.9±8.8 L; P\u3c 0.001, d\u3c 7.17) compared to CTRL (52.4±10.9 L), while higher-volume HIIT was greater than both MICT and low-volume HIIT (P\u3e0.001). Modified-HIIT and MICT increased fat oxidation post-exercise compared to CTRL (P\u3c 0.015). CONCLUSION: Modifying low-volume HIIT with extra bouts to match MICT duration produces greater responses to exercise metabolism