30921 research outputs found
Sort by
Electrochemical detection of mycotoxins in grain matrices using aptamer chemistry
No full textMycotoxins are toxic metabolites produced by fungi and are some of the most common grain contaminents. In addition to posing a significant threat to the quality of food and animal feed, mycotoxins are harmful and can be found in water sources and soil. Contaminations with mycotoxins lead to significant economic losses, especially in Canada. Ochratoxin A (OTA) and deoxynivalenol (DON) are two of the most prevalent mycotoxins, and are therefore the main focus of this thesis.
The standard methods for detecting mycotoxins in grain matrices include Liquid Chromatography-Mass Spectrometry (LC-MS), Enzyme-Linked Immunosorbent Assay (ELISA), and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS). Although these technologies have high sensitivity and accurate, they are costly, time-consuming, and require highly skilled personnel. This thesis explores an electrochemical method based on aptamer chemistry as alternative to detect mycotoxins in grains.
The electrochemical sensor consists of a gold electrode modified with an aptamer, which is labeled with a methylene blue redox tag. After optimization and using square wave voltammetry, the developed aptasensor achieves detection limits that meet food safety standards. This thesis demonstrates the electrochemical quantification of OTA and DON in wheat matrices. Overall, this study highlights a user-friendly electrochemical method with potential future application in grain quality control, representing a promising new approach to address mycotoxin contamination in agricultural products.October 202
The Mechanical behaviour of crowns fabricated from Multilayered Zirconia for mandibular molars in bruxers using Finite Element Analysis (FEA).
No full textThe mechanical behaviour of crowns fabricated from Multilayered Zirconia for mandibular molars in bruxers using Finite Element Analysis (FEA).
Purpose: To evaluate and compare the mechanical behaviour of crowns made from multilayered zirconia for mandibular molars using finite element analysis (FEA) with the elastic modulus derived from nanoindentation testing, and to compare it with the reference monolithic zirconia crowns.
Material & Methods:
Two rectangular samples of multilayer Zirconia, ZirCAD Prime and ZirCAD Prime Esthetic, each measuring 10 mm x 16 mm x 4 mm, were prepared and tested for Nanoindentation using a Hysitron Nanoindenter. Ten readings were taken for each layer of Enamel, Intermediate, and Dentine, and the average value of elastic modulus and hardness were calculated and used to test the Finite Element Analysis of the crowns under various loading conditions. A mandibular left first molar typodont tooth was prepared for a full-coverage Zirconia crown with two different occlusal reductions of 1 mm and 1.5 mm and a full-coverage Crown was designed using in-lab CAD software. 3D models of tooth preparation and full-coverage crowns were created and merged using HyperView Player 2022.3 software. The tooth-crown complex underwent a vertical loading and horizontal loading of 540N and 200N, respectively, in the central fossa, as well as the buccal cusps, and the Maximum principal Stresses were calculated in the Zirconia crowns. The material properties were assumed to be homogeneous, isotropic, and linearly elastic.
Results: 1 mm crowns experienced higher tensile and maximum principal stresses than 1.5 mm crowns, regardless of material. Horizontal forces increased stresses across all crown types and thicknesses. All Zirconia types showed similar behavior under the same conditions. Maximum principal stresses in crowns ranged from 90.4 to 154.4 MPa, while in tooth structure, they ranged from 1.2 to 22.9 MPa.
Conclusion: Increasing the thickness of the crown material reduces the stresses transmitted to both the crown and the tooth structure. More stresses were observed in the crown-tooth assembly under horizontal loading compared to axial/vertical forces. No differences in Maximum principal stresses were observed between the different Zirconia crown materials.October 202
Association of white matter injury and neuroinflammation in the post-acute phase after ischemic stroke using [18F]FEPPA-PET/MRI
No full textBackground: Cerebral white matter (WM) injury after ischemic stroke is associated with post-stroke cognitive impairment (PSCI), however, the interaction between sustained neuroinflammation and post-stroke WM injury is not well understood. Hybrid PET/MRI can provide insight into pathophysiological mechanisms linking chronic neuroinflammation, ischemic WM injury, and PSCI. Using PET/MRI, this study investigated the relationship between [18F]FEPPA standardized uptake value ratio (SUVr) measurements of glial activation and diffusion tensor imaging (DTI) measurements of microstructure integrity in brain WM regions in the chronic phase at 6-months after acute ischemic stroke.
Results: [18F]FEPPA-PET, DTI, and T2-weighted FLAIR were acquired at 6-months post-stroke in 19 elderly humans (seven females; mean age = 76 ± 5 years) with confirmed first-ever acute ischemic stroke using hybrid PET/3T-MRI. Index infarcts, chronic (incidental, covert) infarcts, and WM hyperintensities were manually segmented on FLAIR and excluded from the imaging analysis. Pearson correlation was conducted to assess the association between [18F]FEPPA-SUVr and DTI measurements in WM regions commonly implicated in PSCI. [18F]FEPPA-SUVr was elevated in brain regions ipsilateral to the index infarct at 6-months post-stroke, and these increases correlated with decreases in fractional anisotropy in several WM pathways linked to PSCI, including right superior longitudinal fasciculus (SLF) III (r = -0.82, p < 0.0001), right anterior thalamic radiation (r = -0.61, p = 0.006), and right arcuate fasciculus (r = -0.56, p = 0.01). Elevated [18F]FEPPA-SUVr was also associated with increased mean diffusivity (r = 0.69, p < 0.001), axial diffusivity (r = 0.55, p = 0.02), and radial diffusivity (r = 0.74, p < 0.001) in right SLF III.
Conclusions: This study found an association between elevated post-acute glial activation (neuroinflammation) and reduced microstructure integrity in brain WM pathways ipsilateral to ischemic infarcts and remote from WM lesions at 6-months post-stroke. Hybrid PET/MRI is promising to be a valuable tool for probing post-acute neuroinflammation and associated changes in cerebral WM pathways following ischemic stroke
Neutrophil-mediated inflammation linking cigarette smoke exposure to rheumatoid arthritis pathogenesis
No full textRheumatoid arthritis (RA) is a chronic autoimmune disorder marked by joint inflammation and progressive destruction, often preceded by the appearance of anti-citrullinated protein antibodies (ACPA). While genetic predisposition such as the presence of HLA-DRB1 shared epitope alleles plays a major role in disease susceptibility, environmental factors are also critical in triggering disease onset. Among these, cigarette smoking is the most well-established risk factor, particularly in individuals who develop ACPA-positive RA. Despite this association, the precise mechanism linking cigarette smoke exposure to RA development remains incompletely understood. The "mucosal origins hypothesis" proposes that RA may initiate at mucosal surfaces, such as the lungs, where early immune dysregulation occurs. Notably, cigarette smoke induces lung inflammation that promotes the recruitment of neutrophils into the lungs. These neutrophils can release neutrophil extracellular traps (NETs) enriched with citrullinated proteins through activation of Peptidyl Arginine Deiminase (PAD), the enzyme that generates citrulline. Given this triad of cigarette smoking, lung neutrophilia, and the generation of citrullinated autoantigens, we aimed to investigate the contribution of cigarette smoking in the initiation of autoimmunity in RA. We hypothesized that neutrophils generate citrullinated proteins through the formation of NETs and activation of PAD4. This study investigated how cigarette smoke modulates neutrophil function and inflammation in the context of RA.
The in vitro findings suggested that, cigarette smoke extract (CSE) induces PAD4-dependent NETosis in the absence of microbial triggers and this pathway is likely mediated by the stable chemical components present in CSE medium. While CSE did not induce degranulation, it enhanced neutrophil responses in the presence of foreign particles, indicating selective functional modulation.
Using the collagen-induced arthritis (CIA) mouse model combined with cigarette smoke (CS) exposure we observed increased lung neutrophil infiltration and protein citrullination, with more pronounced effects after prolonged exposure. Elevated NE levels and increased CCL4 expression in the CIA-CS group, highlight a neutrophil-driven inflammatory lung environment.
Collectively, these findings reveal a complex interplay between CS exposure, neutrophil-mediated inflammation, and the development of inflammatory arthritis. Overall, our findings suggest that pulmonary neutrophil infiltration may drive differences in inflammatory arthritis through the formation of immunogenic citrullinated proteins in NETs.February 202
Physical and nutritional quality of extruded high-moisture meat analogues made from sunflower meal and pea protein blends
No full textIntroduction: Incorporating protein-rich food industry by-products, such as sunflower meal (SFM), into foods aligns with United Nations Sustainable Development goals, as it offers environmental-friendly food alternatives for a secure food future. SFM is rich in protein and indispensable amino acids, making it a promising candidate for enhancing the nutritional quality of novel foods such as plant-based meat analogues. This study investigated the production of high-moisture meat analogues (HMMAs) using blends of expeller-pressed SFM and pea protein isolate (PPI).
Methods: Defatted SFM was produced using a laboratory-scale expeller press, which extracted oil from dehulled sunflower seeds at a controlled temperature of 70°C. The blends for extrusion contained 40% SFM-60% PPI and 50% SFM-50 % PPI to achieve a balanced amino acid composition. During extrusion, the cooling die temperature was maintained at 80-50°C, with a screw speed of 200 rpm and a feed rate of 0.5 kg/h (d.b.). The effects of feed moisture content (FMC) (48% and 58%, w.b.), extruder barrel temperature profile (60-80-115-125°C, 80-100-125-135°C, and 100-120-135-145°C), and SFM concentration (40% and 50%) on the physical (texture and color) and nutritional (protein quality and anti-nutritional factors) properties of the resulting HMMAs were examined.
Results: The HMMAs produced in this study had comparable protein quality to real meat, with 70-74% (d.b.) protein content and 86-89% in-vitro protein digestibility, while tryptophan was the first limiting amino acid. The texture and color analysis showed that the meat analogues were harder and darker than cooked chicken. The HMMAs became softer and lighter in color as FMC increased and extrusion temperature decreased. Moreover, extrusion processing significantly (p < 0.05) reduced the levels of anti-nutritional compounds including phytic acids, trypsin inhibitors, and chlorogenic acid.
Conclusion: This research offered valuable insights into the potential of replacing PPI with SFM to produce HMMAs, demonstrating a sustainable way to add value to an underutilized by-product in the food industry. The understanding of the effect of extrusion conditions on the physical and nutritional properties of SFM-PPI blend-based meat analogues is important for the development of high-quality plant-based protein products.October 202
Antimuscarinic drugs exert β-arrestin-biased agonism at the muscarinic acetylcholine type 1 receptor
No full textThe M1 muscarinic acetylcholine receptor (M1R) is highly expressed in the nervous system, and has been studied to discover new therapeutic drugs for a range of neurological and psychiatric disorders. Studies from our lab and others also highlighted the fact that antagonists of M1R could be therapeutic agents for neuropathies. However, the mechanism(s) of action through which M1R antagonists exert their therapeutic effects are not well understood. Previous studies indicate that both pirenzepine (PZ), a selective M1R antagonist, and muscarinic toxin 7 (MT7), a negative M1R allosteric modulator, act via M1R to promote neuritogenesis in rodent primary dorsal root ganglia (DRG) sensory neurons, in part, through β-arrestin-dependent activation of extracellular signal-regulated protein kinase 1/2 (ERK1/2). Furthermore, these antagonists reverse nerve degeneration in a variety of rodent models of peripheral neuropathy through multiple complementary pathways. To understand the therapeutic effects and mechanism of M1R antagonist-induced ERK1/2 phosphorylation, we tested the hypothesis that PZ and MT7 possess β-arrestin-biased agonism at M1R to drive activation of ERK and enhance neurite outgrowth. Treatment for up to 30 min with PZ and MT7 dose-dependently recruited β-arrestin2 to M1R (analyzed using nano-BRET) and increased ERK phosphorylation in both HEK293 cells and DRG neurons. These novel pharmacological effects occurred in the absence of activation of G protein signaling or receptor internalization. PZ promoted M1R phosphorylation at six specific serine/threonine residues (Thr230, Ser251, Thr254, Ser321, Thr354, Ser356) and deletion mutation of these sites suppressed PZ and MT7 induction of β-arrestin binding to M1R and inhibited ERK activation. β-arrestin-biased activity of PZ and MT7 involved the mobilization of casein kinase 2 (CK2) and this occurred in the absence of Gαq or G protein receptor kinase (GRK) activity. Pharmacological or siRNA-based inhibition of CK2 blocked PZ-induction of β-arrestin association, ERK activation and neurite
outgrowth in DRG neurons. In conclusion, PZ/MT7 activated M1R toward the β-arrestin signaling pathway in both HEK293 cells and DRG neurons to augment ERK activation and neurite outgrowth via engagement of CK2. Results of this work provide novel findings with far reaching consequences on our understanding of the signaling mechanism of antimuscarinic drugs.October 202
EpOMEs and DiHOMEs require TRPA1 and/or TRPV1 to induce calcium flux in human airway smooth muscle
No full textIntroduction:Oxylipins are bioactive lipid mediators found throughout the lung and can act on Airway Smooth Muscle (ASM). Well-characterized species such as thromboxanes and leukotrienes elevate cytoplasmic calcium (Ca2+) in ASM, initiate ASM contraction, and induce airway narrowing. Oxylipin profiles are changed in individuals who are exposed to pollution, allergens, and who live with asthma. However, many oxylipins, including EpOMEs and DiHOMEs have unknown functions related to Ca2+ flux and contraction in ASM. I propose that EpOMEs and DiHOMEs are capable of elevating Ca2+ flux in ASM cells and may be detrimental in obstructive diseases like asthma.
Methods:Senescence-resistant human ASM cells were cultured and loaded with Ca2+ indicator dye Fura-2 or Fluo-4. ASM were exposed to 10µM of 9,10 EpOME, 12,13 EpOME, 9,10 DiHOME, or 12,13 DiHOME and Ca2+ data was captured using fluorescent microscopy. ASM cells were loaded with inhibitors for cation channels Transient Receptor Potential Ankyrin 1 (TRPA1) (HC-030031), Transient Receptor Potential Vanilloid 1 (TRPV1) (AMG 517), and Gadolinium (GD3+). ASM were then exposed to individual oxylipins at 10µM, and fluorescent data was captured.
Results:9,10 EpOME, 12,13 EpOME, 12,13 DiHOME induced a significant increase in intracellular calcium ([Ca2+]i) compared to vehicle. 9,10 DiHOME was capable of inducing an increase in [Ca2+]i but did not reach threshold for significance. HC-030031 caused a significant 66% reduction in 9,10 EpOME’s Ca2+ response. AMG 517 was capable of significantly reducing 12,13 EpOME’s response by 80% while HC-030031 significantly augmented 12,13 EpOME’s response by 61%. AMG 517 and HC-030031 reduced 9,10 DiHOME’s response significantly by 79% and 46%, respectively. HC-030031 was capable of significantly reducing 12,13 DiHOME’s response by 65%.
Conclusion:These results show for the first time that EpOMEs and DiHOMEs are capable of increasing [Ca2+]i in ASM cells. Additionally, EpOMEs and DiHOMEs require TRPA1 and/or TRPV1 to induce Ca2+ flux in ASM. EpOMEs and DiHOMEs are abundant in the lung and may initiate ASM contraction and airway narrowing through Ca2+ mechanisms. Future studies are required to understand the contractile abilities of EpOMEs and DiHOMEs and determine if they are detrimental in human airways, especially in obstructive disease like asthma.October 202
“Farmer/Herder” conflicts and the prospects of local peacebuilding: The case of Agogo in the Asante-Akyem North municipal assembly of Ghana
No full textThis study investigates the complex dynamics of farmer/herder conflicts in Ghana, particularly focusing on the role of identity in these disputes. Unlike other West African countries where conflicts are primarily driven by resource scarcity, Ghanaian conflicts between indigenous farmers and Fulani herdsmen are significantly influenced by issues of identity and the perceived non-indigeneity of the Fulani. This study examines how being labeled as an “Other” impacts the socioeconomic opportunities for Fulani herdsmen and explores the link between citizenship rights and these conflicts.
Employing a qualitative research approach, the study utilizes individual interviews and group observations in Agogo—an area with a pronounced history of frequent conflicts between Fulani herdsmen and local farmers. By applying identity theories and critical and emancipatory peacebuilding frameworks, the research analyzes participants’ lived experiences and the broader implications for peace and security.
The study also highlights the crucial roles of women and youth in peacebuilding efforts within Agogo. It incorporates recommendations and practical strategies proposed by the participants themselves, including both farmers and Fulani herdsmen. These recommendations stress the need for designated areas for farming and pastoral activities, enhanced cross-cultural dialogue, and peace education initiatives. For the people of Agogo, peace encompasses not just the absence of violence but also social and economic development, access to amenities, and overall well-being. This research provides valuable insights into the multifaceted nature of farmer/herder conflicts in Ghana and offers participant-driven strategies for strengthening peacebuilding efforts.
The key findings include deep-rooted tensions over land use, water access, and crop destruction by cattle, which fuel hostility between farmers and herders. Further, prejudicial “othering” of the Fulani herdsmen and media stereotypes exacerbate mistrust, while the exclusion of farmers, youth, and women from land distribution decisions intensifies grievances. The study also found that gender-based violence contributes to fear and insecurity in Agogo. The findings also reveal generational differences in peacebuilding approaches and highlight how varying views on conflict resolution, patriotism, and community values contribute to ongoing tensions. Additionally, challenges like corruption, ineffective leadership, and inconsistent policies are identified as obstacles to effective peacebuilding.University of ManitobaOctober 202
Deep-amplicon sequencing for monitoring impacted waterways in rural Manitoba
No full textAquatic environments across Canada constantly receive anthropogenic discharge. In this context, water is considered the main vehicle for the dissemination of pathogens into the environment. The current assessment of microbiological water quality indicators focuses on fecal bacteria such as E. coli, overlooking viruses and protozoa. Monitoring impacted freshwater ecosystems without focusing on single microorganisms offers fundamental data to develop new microbial indicators for aquatic contamination. A longitudinal, 8-month amplicon-based analysis was performed in the Assiniboine River to identify the microbial composition, relative abundance, and environmental structuring factors in water associated with different anthropogenic activities. Bacteriophages, bacteria, and microeukaryotes were studied using the major capsid protein gene g23, 16SrRNA, and 18SrRNA genetic markers with Illumina technology. Our analysis revealed the riverine ecosystems were compounded in the majority by cyanophages (62%) (Synechococcus phages, and Bellamyvirus genus phages), Escherichia coli phages (26%), Emdodecavirus genus phages (8%), and Slopekvirus genus phages (2%). The most relatively abundant bacterial families across waterways included Sporichthyaceae (20) %, Pseudomonadaceae (19%), Enterobacteriaceae (14%), Burkholderiaceae (8%), Spirosomaceae (7%) , Flavobacteriaceae (3%), Aeromonadaceae (3%), Micrococcaceae (3%) and Nostocaceae (3%). The microeukaryotic structure consisted of Mediophyceae (24%), Cryptomonadales (14%), Choreotrichia (14%), Oligotrichia (3%), Sphaeropleales (7%), Chlamydomonadales (1%), Kappamyceteceae (5%), and Thoracosphaeraceae (3%). The effects of location and sampling months for bacteriophages were inconclusive. Sampling months affected the community structure of bacteria and microeukaryotes significantly. Forested, urban and agriculturalD activities significantly shaped microeukarytic communities. Microbial communities were highly impacted by environmental factors, especially daylight length, water temperature, dissolved oxygen (DO), and precipitation. Our results also revealed complex networks of trophically interacting microorganisms between primary producers, heterotrophic bacteria, and predators (i.e. Oligotrichia). These results are critical to better understanding the dynamic interplay and the effect of temporal changes in microbial fractions as well as providing essential information for new potential indicators for aquatic contamination.Research Manitoba New Investigator Operating grant: No 5385;
University of Manitoba Indigenous Research Program Project No. 54345.
The Visual and Automated Disease Analytics (VADA) program:
Indigenous CREATE.February 202
Extrinsic and intrinsic factors impacting Cape ground squirrels’ hair cortisol
No full textGlucocorticoids (GCs) increase during the stress response, so they are commonly studied to measure the chronic stressors an animal experiences. However, GCs can also decrease in response to stimuli they are adapted to, also known as harsh conditions, as a mechanism to conserve energy. Because GCs are closely linked to fitness and survival, understanding how animals' GC levels respond to their environment is crucial. Therefore, this thesis aims to study the changes in hair cortisol, a common GC studied in mammals, of an arid-adapted, egalitarian social species, Cape ground squirrels (Xerus inauris), due to extrinsic and intrinsic factors. We also explored the impact of GCs on reproductive success in adult females. We first examined cortisol responses to temperature, rainfall, and group size in adult female Cape ground squirrels across eight years. We found that squirrels illustrate a decrease in cortisol with increasing temperature maximums, suggesting that Cape ground squirrels are adapted to hot temperatures (harsh conditions) that require a metabolic response. There was no significant relationship between hair cortisol and temperature minimums, rainfall, or group size. We then examined hair cortisol and its relationship with intrinsic factors and reproductive success in adult female Cape ground squirrels. Age, body condition, ectoparasite abundance, and prevalence of nits did not have a significant relationship with cortisol. We also found that decreases in cortisol were associated with a lower reproductive success rate, also supporting that cortisol in these squirrels reflects metabolic energy needed for reproduction. Cape ground squirrels are income breeders, so they spend energy on reproduction when it becomes available. Overall, our research supports the hypothesis that hair cortisol in Cape ground squirrels reflects their metabolism and allocation of resources rather than chronic stress. This research is particularly relevant in the context of climate change, as understanding the relationships between GCs, reproduction, and environmental factors will become increasingly important as Cape ground squirrels' habitats continue to change.February 202