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Type d'Item : Item , Elucidating the Molecular Mechanisms of Host Susceptibility to Salmonella Typhimurium Infection by IFN-I Signaling(Université d'Ottawa / University of Ottawa, 2026-08-31) Chehab El Din El Hamra, Rayan; Sad, Subash; Blais, AlexandreSalmonella enterica serovar Typhimurium (ST) is considered a non-typhoidal strain of Salmonella, which causes progressive diseases in susceptible mice, resembling typhoid-like fever. Salmonella infection occurs due to the ingestion of contaminated food and water supplies and is a major public health concern. In immunocompromised individuals, this strain can be fatal, with reports of an estimated 2 million deaths each year. This makes understanding the molecular mechanisms behind ST infection of vital importance. Type I interferons (IFN-I) are crucial in the immune response, but their role against bacterial infections remains elusive. While IFN-I signaling is critical for antiviral immunity, we show that IFN-I signaling promotes susceptibility to ST infection. Despite reduced innate immune pathways such as TLR and IFNγ signaling, Ifnar1⁻ᐟ⁻ BMDMs exhibit enhanced resistance against ST, indicating the involvement of non-canonical protective mechanisms. We find that the induction of interferon-stimulated genes by IFN-I signaling suppresses protein synthesis, which limits antimicrobial activity during ST infection. In contrast, Ifnar1⁻ᐟ⁻ BMDMs display increased protein synthesis and metabolic activity, supporting improved intracellular control of ST. Notably, Irf9⁻ᐟ⁻ BMDMs display increased and sustained STAT1 signaling while maintaining this metabolically active state, resulting in enhanced survival and resistance compared to Ifnar1⁻ᐟ⁻ mice. Together, these findings demonstrate that IFN-I signaling drives translational repression to restrict immunometabolic responses necessary for controlling ST infection.Type d'Item : Item , Food Screeners for Adolescents: A Hybrid Review Focused on Their Psychometric Properties(Université d'Ottawa / University of Ottawa, 2026-08-31) Roe, Emma; Tugault-Lafleur, Claire N.Food screeners are a low-cost, low-burden option for nutrition surveillance, but their number and variability complicate tool selection for adolescents. This review aimed to describe food screeners used among adolescents in high-income countries and evaluate their validity and reliability. A hybrid approach was used: a scoping review to identify existing screeners and a systematic review to assess psychometric quality. Screeners with ≤30 items targeting healthy adolescents aged 10-17 years were eligible. Forty-seven screeners were identified through both searches. Instruments averaged 16 items with 22 including portion size questions, and 26 assessing alignment to dietary guidelines. Twenty-six screeners had psychometric evidence, and 18 met quality criteria. Construct (convergent) validity was most frequently examined, with most estimates falling in the poor-moderate range, whereas reliability was generally stronger, with most instruments demonstrating acceptable test-retest performance. Findings highlight substantial variability and key gaps in adolescent food screener evaluation.Type d'Item : Item , Income-tested and in-kind: The material wellbeing effects of the Canadian Dental Care Plan(2026-08) Notten, GerandaRich countries increasingly rely on income-testing and their income-tax system to deliver both cash and in-kind transfers to recipients. This research measures the material wellbeing effects of the in 2023 introduced Canadian Dental Care Plan (CDCP). Using four measures of material deprivation, it reveals material wellbeing effects that are either missed entirely or are misestimated by income (poverty) measures. It further demonstrates three new Cost-Effectiveness Ratios (CER) that further contribute to filling current evidence gaps. The CDCP is income-tested and covers dental care costs of households with an income below $90,000 who do not have a dental plan. Using microdata from 2023 and 2025, the research uses the staggered introduction of the CDCP and the doubly robust difference-in-difference estimator to estimate the impact of the CDCP on seniors. The research estimates that the CDCP reduced the incidence of dental care deprivation among seniors by 8.7 percentage points, which amounts to a 62 percent decline compared to the 2023 baseline. Further estimates indicate, among others, that the CDCP averted close to 700 thousand cases of dental care deprivation at a cost of about 50 million dollar per percentage point reduction in dental care deprivation. This suggests that the CDCP made a substantive contribution toward addressing the specific barrier it was designed to reduce. More broadly, this research shows that outcome-based measures of material wellbeing, such as dental care deprivation, provide unique insights on the material wellbeing effects of social and health programs and thereby also offer novel opportunities for assessing their cost-effectiveness.Type d'Item : Item , Arcuate Nucleus Neurons Regulate Ventral Subregion Ventricular-Subventricular Zone Neural Stem Progenitor Cell Differentiation Through Endocannabinoid Signaling(Université d'Ottawa | University of Ottawa, 2026-08-28) Sun, Yiren; Wang, JingNeural stem and progenitor cells in the ventricular-subventricular zone (V-SVZ) have been a long sought-after source of neurogenic potency. Although activation signals for NSPCs are well-described, difficulties arise in harnessing these NSPCS as isolating differentiation-specific signals remain elusive in vivo. Here, we report that monoacylglycerol lipase (Mgll), a homeostatic enzyme that attenuates synaptic endocannabinoid responses, is a physiological gatekeeper for NSPC differentiation. Remarkably, Mgll expression is non-cell autonomous, originating in axons from neurons innervating the V-SVZ. Furthermore, pathological conditions show early spatiotemporally-distinct overexpression of Mgll in the hypothalamic arcuate nucleus (ARC) of 3xTg Alzheimer’s disease mice (3xTg-AD). ARC Mgll overexpression is coupled to inhibition of differentiation and neurogenesis in the ventral V-SVZ subregion, culminating in olfactory behavioral deficits. Mechanistically, this spatiotemporal Mgll overexpression and subsequent ventral V-SVZ differentiation deficits originate from defective ARC-specific aPKC-CBP signaling. Conversely, spatial transcriptomics shows Mgll deletion in ARC POMC+ neurons increases ventral V-SVZ-specific expression of pro-differentiation transcription factors Nf1x and Nf1b, driving neurogenic and gliogenic lineage commitment. Finally, deleting Mgll in the ARC from mice with dysregulated aPKC-CBP signaling rescues ventral V-SVZ-derived neurogenesis deficits through Nf1x expression. Our study implicates a neuronal homeostatic mechanism in regulating V-SVZ NSPC differentiation and demonstrates that this mechanism is spatiotemporally dysregulated under pathological conditions. These findings show that interacting with neuronally-derived Mgll is a promising strategy to precisely restore neurogenic potency.Type d'Item : Item , The Effects of Synthetic Sex Hormones on Cognitive Abilities, Affective State, the Gut-Brain Axis, and Acute Immune and Stress Reactivity During Puberty and Adulthood(Université d'Ottawa | University of Ottawa, 2026-08-28) Kheloui, Sarah; Ismail, NafissaCombined oral contraceptives (COCs) are one of the most widely used forms of hormonal contraception by both adolescent and adult human females. While they are very effective at preventing pregnancy, they may also have effects on the central nervous system, cognition, and behaviour. However, there are a lot of inconsistencies reported on these effects. One possible explanation for these discrepancies could be that the effects of COCs on the brain are age-dependent and may be more pronounced during puberty and adolescence. The mechanisms underlying the effects of COCs on the brain and behaviour also remain unclear. The current thesis was designed to address these knowledge gaps and to investigate possible mechanisms through which COCs could impact the brain, cognitive abilities, and gut microbiome composition in an age-dependent manner in a mouse model (Article 1). Subsequently, we examined the effects of pubertal COC exposure on mental health outcomes such as depression-like and anxiety-like behaviors (Article 2). Lastly, we investigated whether COCs alter immune and stress responses in pubertal and adult CD-1 mice (Article 3). Together, the studies included in this dissertation furthers our understanding of the impact of combined oral contraceptives use during puberty and adulthood on women’s health including the brain, behaviour, gut microbiome as well as stress and immune systems.