OPUS: Open Ulethbridge Scholarship
Open ULeth Scholarship (OPUS) is the University of Lethbridge's open access research repository. It contains a collection of materials related to research and teaching produced by the academic community.
Self-archiving your research in OPUS is one way to meet Open Access policies of granting agencies. It is important to retain your final, post-peer-reviewed drafts for submission to OPUS, as this is often the only version publishers will allow to be archived. Click here for information on the U of L Open Access Policy.
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Investigating the efficacy of cannabis as a novel therapeutic modality for aggressive pediatric brain and nervous system tumors
(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Malach, Megan Shirley; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, Olga; Kovalchuk, Igor
Cannabis sativa is a plant that has been used medicinally for thousands of years. In recent decades, interest in cannabis as an anti-cancer therapy has gained interest and numerous preclinical studies have demonstrated the anti-cancer abilities of a variety of human cancer types. However, most of these studies have been in only adult cancers and tumors and have almost entirely used individual cannabinoids as treatments. Here, we demonstrate the anti-cancer abilities of a cannabis extract on models of two pediatric brain tumors, neuroblastoma and atypical teratoid/rhabdoid tumors. Neuroblastoma is an extremely common pediatric solid tumor of the nervous system, and its high-risk iterations pose a clinical problem requiring novel therapeutic solutions. Atypical teratoid/rhabdoid tumors are extremely rare solid tumors of the central nervous system that occur almost exclusively in children under 3 and extremely poor prognoses. Thus, the investigation of novel treatment strategies for this tumor is warranted. Here, we demonstrate that cannabis extract is able to reduce viability and induce apoptosis and cell cycle arrest in models of both tumor types, and that this effect is driven not via the constituent cannabinoids of the extract, but via the entourage effect, as individual cannabinoid and terpene components of the extract, whether alone or in combination, failed to reproduce the anti-cancer effects of the whole extract. We also demonstrate that two of these terpenes, citronellol and α-cedrene, are capable of inducing anti-cancer effects, including reductions in viability, small increases in apoptosis, and similar mechanisms of cell cycle arrest as whole extract. However, the effect of individual agents, even in combination, fail to recapitulate the observed anti-cancer effects of whole extract. Overall, this research demonstrates that investigation of whole-cannabis extracts is a novel and worthwhile pursuit for pediatric solid nervous system tumors in need of novel therapies.
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Boreal ecosystem changes due to permafrost thaw across the discontinuous to sporadic permafrost zone
(Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment, 2024) Flade, Linda; University of Lethbridge. Faculty of Arts and Science; Chasmer, Laura; Hopkinson, Christopher
This PhD thesis developed a framework to model, quantify, and improve understanding of spatially explicit changes in short-to-tall-stature vegetation structure in the southern Taiga of northwestern Canada. This region is still changing due to the retreat of the Laurentide Ice Sheet since the last glacial maximum (~22.1 cal ka BP). In addition, climate change has caused rapid ecosystem changes, for example due to permafrost thaw, with implications to carbon sink strength and wildland fire susceptibility, amongst others. Regional allometric equations for shrubs and short-stature trees were developed to estimate aboveground biomass (AGB) and live aboveground plant carbon stocks using 1D, 2D, and 3D field measurements. Spatially coincident bi-temporal airborne lidar data were used to develop a single AGB model applicable across changing relationships between lidar point clouds and AGB magnitudes as ecosystems change form, ecosystem boundaries expand and recede, and airborne lidar technologies evolve. By fusing field data with bi-temporal airborne lidar data, the study quantified and analyzed changes in vegetation structure and aboveground plant carbon stocks. By employing geospatial statistical analysis and machine learning the underlying important drivers of these changes were identified.
Key findings of this thesis were the following: (1) the developed framework has improved understanding of the magnitudes and directions of short-to-tall-stature vegetation structural changes over the past decade (2010 to 2019); (2) increases in the growth and abundance of short-stature vegetation were substantial across the study region and need to be integrated into carbon accounting frameworks with extension to unmanaged forest and peatland ecosystems. Overall, the established framework could aid in the modelling of wildland fire fuel dynamics and fire behavior also in peatlands, which could reduce community risk to fire in this region.
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How do social and demographic characteristics interact to influence the perceived mental health of Canadian immigrants compared to the total population of Canadians
(Lethbridge, Alta. : University of Lethbridge, Faculty of Health Sciences, 0025) Thapa, Rama; Kellett, Peter
The immigration process and settlement are stressful, and the mental well-being of immigrants is of particular concern. Epidemiological studies suggest that first-generation (foreign born) immigrants experience better mental health than the Canadian-born population. Still, it is unclear whether this pattern varies substantially by the intersection of science & demographic factors. Cross-sectional data from public-use Canadian Community Health Survey (CCHS) 2017/2018 was used, representing the Canadian population aged 12 years of older residing in all ten provinces. The perceived mental health of Canadian immigrants was assessed, and the influence of social and demographic factors on the mental health of Canadian immigrants was explored. Descriptive statistics and logistics regression were used to describe demographic characteristics, and their association with perceived mental health of immigrants comparing to the total Canadian population. Younger individuals in the general population and older immigrants had a higher proportion of reporting poor mental health. Immigrants with longer residency (more than 10 years) in Canada reported higher odds of poor mental health. Canadians who had a household size 2 and owned their house reported poor mental health, whereas immigrants who rented and lived alone, reported poor mental health. There was an increased odds of reporting poor mental health among the middle-aged Canadians (35-49 yrs.), while non-significant results among immigrants suggests that age plays less of a rold in immigrants. Similar results were noted for sex, sexual orienation, household size, racial background and dwelling ownership among immigrants, suggesting that results may vary due to multiple factors intersecting with each other which potentially plays a more substantial role in immigrants' mental health outcomes.
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Can seizures be forgotten? Rapamycin and isoflurane do not disrupt epileptogenesis in a mouse model of epilepsy
(Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience, 2024) Howey, Carlos J.; Luczak, Artur
Epilepsy is a neurological disorder, characterized by recurring seizures, that affects approximately 50 to 70 million people worldwide. Understanding how neurons generate abnormal electrical activity is central to the search for an effective treatment. It was hypothesized that the same biochemical processes that support normal synaptic plasticity may play a role in epileptogenesis. To explore this, a kindling model of epilepsy was used. Seizures were induced in mice through electrical stimulation of the amygdala. After the mice displayed seizures of intermediate intensity, they received a treatment of rapamycin (40 kg/mg, i.p.), a compound implicated in affecting synaptic plasticity. Following rapamycin treatment, the mice were also treated with isoflurane (2.5 % in oxygen), an anesthetic that reduces neuronal activity. It was found that rapamycin and isoflurane did not reduce seizures. It is possible that the treatments had no effect, since they had commenced after the animals displayed intermediate seizures; treating the animals at earlier stages could be more likely to disrupt the progression of seizures, however this question will be addressed in further studies. Following the treatments, the mice were then subjected to a Morris water maze task to test the effects of kindling on spatial memory. It was found that the mice with advanced seizures performed the task as well as the mice that were not kindled.
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Ecological studies of parasitoid hymenopterans (subclade Parasitoida) in southern Alberta agricultural systems
(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Pawluk, Abbe D.; University of Lethbridge. Faculty of Arts and Science; Laird, Robert A.; Cárcamo, Héctor
Parasitoid hymenopterans are important biocontrol agents of agricultural pests. Despite their relevance to sustainable agriculture and an integrated pest management strategy, this subclade of insects is understudied. Here, we conducted two studies related to the biology of parasitoid hymenopterans in southern Alberta: 1) A survey of parasitism rates by a native genus of parasitoid, Peristenus, on a significant agricultural pest, Lygus, across 17 cultivated and uncultivated host plants; 2) A survey of parasitoid genera in canola fields as part of a study on the influence of type of edge boundaries and distance from the edge on parasitoid populations and diversity. Mean Peristenus-Lygus parasitism rates ranged from 0 – 45% across various host plant species, with a significant interaction between instar age and parasitism rates in late-stage canola and hemp. Type of edge boundary and distance from the edge did not significantly affect Hymenoptera diversity, and Diolcogaster is reported as the dominant genus of parasitoid hymenopterans in canola crops. Both studies contribute to enhanced integrated pest management studies, and more generally, to the understanding of southern Alberta insects.