PRISM :: Browsing by Author "Shearer, Jane"

Browsing by Author "Shearer, Jane"

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Open Access
Acute Impaired Glucoregulation and Disrupted Gastrointestinal Hormone Secretion in Adolescents in Response to Caffeine-Containing and Nutritionally Fortified “Energy Shots”
(2017) Virtanen, Heidi; Shearer, Jane; Ho, Josephine; Pacaud, Danièle; Reimer, Raylene; Michelle, Jackman
Caffeine-containing energy drinks (CCED) are beverages containing simple sugars, caffeine and mixtures of vitamin, mineral and/or herbal preparations which are aggressively marketed to adolescents and young adults. This study analyzed the metabolic impact of acute, non-nutritive sweetener-containing CCED consumption on glucoregulation and gut peptide response in adolescents, and how it is affected by genetic variance. CCED consumption induced acute insulin resistance following an oral glucose tolerance test when compared with placebo, with glucose and insulin concentrations rising by 15.8% and 73.0%, respectively. Glucagon-like peptide-1, gastric inhibitory peptide, C-peptide, and pancreatic peptide YY concentrations rose following caffeine and decaffeinated treatments when compared with placebo. Genetically fast caffeine metabolizers had exaggerated glucose and insulin curves following caffeine trials, while slow metabolizers were relatively unchanged. This response to CCED consumption could be detrimental to individuals predisposed to metabolic deficits. Results provoke further exploration into the mechanisms involved in this transient insulin resistance.
Open Access
Advancing the Art of Mitochondrial Diagnostics and Therapeutics
(2017) Newell, Christopher; Khan, Aneal; Shearer, Jane; Rho, Jong; Childs, Sarah; Shutt, Timothy; Haqq, Andrea
Objective: Mitochondrial diseases are panethnic genetic disorders, affecting 1:5000 individuals. Currently with no cure, challenges exist in patient diagnosis, measurement of mitochondrial function, and effective therapies. The primary emphasis of this dissertation was to explore diagnostic and therapeutic targets for mitochondrial disease. Investigated therapies included; mesenchymal stem cell (MSC) therapy, dietary interventions, and side alternating vibration training (SAVT). Novel diagnostic approaches employed were; the hybrid blue-clear native polyacrylamide gel electrophoresis (BCN-PAGE), and circulating cell-free mitochondrial DNA (cf-mtDNA) techniques. Methods: C57BL/6 mice were intravenously treated with MSCs following the induction of metabolic inflammation through prolonged high-fat (HF) feeding. A separate cohort of BTBR, autism-phenotype, mice were treated with a ketogenic diet (KD) to examine the impact on mitochondrial dynamics in a disease commonly experiencing mitochondrial dysfunction. These projects involved a combination of mitochondrial bioenergetics (high resolution respirometry), gut microbiome (fecal and cecal), gene expression (qRT-PCR, gene microarray), and mitochondrial morphology (confocal microscopy) experimentation to evaluate the mitochondrial-specific response to each therapy. Thirdly, clinical assessment of SAVT as a therapeutic in mitochondrial disease patients was performed using a 12-week cross-over study design using peak jumping power (PJP) as a primary functional measurement of mitochondrial function. Diagnostically, mitochondria were isolated from control and mitochondrial disease patient skin fibroblasts to compare our BCN-PAGE technique to existing diagnoses. Secondly, blood was drawn from both control and mitochondrial disease patients for clinical comparisons of mtDNA hapolotyping using our cf-mtDNA technique. Results: Therapeutic studies indicate that MSCs improve metabolic capacity, induce widespread gene shifting, and promote healthy mitochondrial morphology in a model of metabolic inflammation. Moreover, KD administration exerts tissue-specific effects including increased mitochondrial turnover in liver, while the brain remained tightly regulated. Clinically, SAVT was well tolerated in mitochondrial disease patients, with improvements in PJP being measured following therapy. Diagnostically, both BCN-PAGE and cf-mtDNA techniques were successfully able to corroborate clinical diagnostic findings. Conclusions: Experiments completed in this dissertation provide insight into various therapeutic opportunities for both mitochondrial disease and diseases involving mitochondrial dysfunction. Furthermore, our less-invasive diagnostic techniques may be useful to monitor the response to future therapies for mitochondrial disease.
Open Access
Association between glycemic load and cognitive function in community-dwelling older adults: results from the Brain in Motion study
(2017) Garber, Anna; Poulin, Marc; Friedenreich, Christine; Csizmadi, Ilona; Longman, Richard S.; Sajobi, Tolulope; Shearer, Jane
Background: Impaired glucose tolerance is a risk factor for non-age-related cognitive decline and is also associated with measures of physical activity (PA) and cardiorespiratory fitness (CRF). A low glycemic load (GL) diet can aid in the management of blood glucose levels, but little is known about its effect on cognition with poor glucoregulation. Objective: The aim of this thesis was to assess the relation between GL and cognitive function by glucoregulation, and possible mediatory effects by CRF and PA, in older adults. Design: A cross-sectional analysis of 194 cognitively healthy adults aged ≥55 years (mean=65.7, SD=6.1) was conducted. GL was assessed using a quantitative food frequency questionnaire, and glucoregulation was characterized on the HOMA-IR index. Subjects also completed a cognitive assessment, CRF testing, a validated self-reported PA questionnaire, and a blood draw. Multiple linear regression models adjusted for significant covariates were used to evaluate the relation between GL and cognition, and mediation analysis was used to assess potential mediatory effects by CRF and PA. Results: GL was inversely associated with global cognition (β=-0.014; 95% CI -0.024, -0.0036) and figural memory (β =-0.035; 95% CI -0.052, -0.018) in subjects with poor glucoregulation. Neither CRF nor PA mediated these relations. In subjects with good glucoregulation, no association was found between GL and cognitive function (p>0.05). Conclusions: A low GL diet is associated with better cognitive function in older adults with poor glucoregulation. This study provides supportive evidence for the role of GL in maintaining better cognitive function during the aging process.
Open Access
Butyrate Alleviates Crohn's Diseases' Adherent Invasive E coli-Induced Mitochondrial Dysfunction in Intestinal Epithelium
(2022-04) Hamed, Samira; McKay, Derek; Shutt, Timothy; Shearer, Jane
Mitochondrial dysfunction can lead to disruption of cellular homeostasis. This can occur because of an existing disease or condition like inflammation and DNA mutations; however, despite not being the main factor initiating the disease (e.g., inflammatory bowel diseases (IBDs)), the mitochondria play an important role in promoting or dampening its severity. Therefore, mitochondrial dysfunction is often not considered diagnostic for a specific condition but reflects the general wellbeing of the cell. This makes analysis of mitochondrial function/dysfunction critical in understanding normal homeostasis and disease, prompting the idea that controlling mitochondrial function is a promising therapeutic target in diseases. In a healthy gut, resident commensal bacteria affect cellular functions, with bacterial fermentation products such as short chain fatty acids (SCFAs) having a wide range of benefits including enhancing mitochondrial biogenesis. However, dysbiosis in the gut of IBD patients decrease the abundance of SCFAs-producing bacterial species, especially butyrate producing bacteria like clostridia. Adherent invasive E. coli (AIEC) is a pathobiont strain of E. coli associated with Crohn’s disease (CD) and was implicated in the pathogenesis of CD through inducing proinflammatory responses. Research from the McKay laboratory demonstrated that in gut epithelial cells (i.e., the T84 human cell line) E. coli LF82 infection caused severe mitochondrial dysfunction. We hypothesized that sodium butyrate (NaB) might protect against E. coli LF82-induced mitochondrial dysfunction. To investigate this, parameters of mitochondrial functions like mitochondrial morphology and membrane potential were measured. E. coli LF82 infection in colonic epithelium induced dramatic mitochondrial fragmentation, loss in mitochondrial membrane potential and reduced mRNA expression of mitochondrial biogenesis regulator, however, NaB treatment protected against E. coli LF82-induced mitochondrial dysfunction. Attempting to identify the mechanism by which NaB protected mitochondrial functions against E. coli LF82 infection, we found that NaB protective effect was blocked when cells were pretreated with Gi subunit inhibitor pertussis toxin (PTX), emphasizing the role of NaB as a ligand for G protein-coupled receptors (GPCRs) GPR41 and GPR109A in this mechanism. The data in this thesis represent a novel perspective on the interaction between a commensal bacteria-derived metabolite and a CD-pathobiont through mitochondrial functions laying the foundation for future studies.
Open Access
Characterizing the Relationship Between Energy Metabolism and Mesenchymal Stem Cell Therapy in the Infarcted Heart
(2013-12-13) Hughey, Curtis; Shearer, Jane
Objective: A constant provision of adenosine triphosphate (ATP) is of necessity for cardiac contraction. If the heart progresses towards failure following a myocardial infarction (MI) it may undergo metabolic alterations that have the potential to compromise its ability to meet energetic demands. The main focus of this dissertation was to evaluate the efficacy of mesenchymal stem cell (MSC) transplantation to mitigate abnormalities in energy metabolism that contribute to ATP synthesis post-MI in the presence and absence of diet-induced insulin resistance. Methods: C57BL/6 mice were chow or high-fat fed prior to induction of a MI via chronic ligation of the left anterior descending coronary artery. Post-ligation, MSCs were transplanted via intramyocardial injection. Serial echocardiography was performed prior to and up to 28 days post-MI to evaluate cardiac systolic function. Hyperinsulinemic-euglycemic clamps coupled with the administration of isotopic tracers were employed post-MI to assess systemic insulin sensitivity and insulin-mediated, tissue-specific substrate uptake in the conscious, unrestrained mouse. High-resolution respirometry was utilized to evaluate cardiac mitochondrial function in saponinpermeabilized cardiac fibers. Western blotting was completed to assist in identifying molecular mechanisms through which the MSC therapy may modulate cardiac and systemic metabolic phenotypes. Results: The improved systolic performance in MSC-treated mice was associated with a lessening of non-pathological in vivo insulin-stimulated cardiac glucose uptake. The changes in glucose uptake may have been via the MSC-mediated alterations in fatty acid availability/utilization. MSC therapy preserved fatty acid uptake in the absence of diet-induced insulin resistance. Conversely, the cell-based treatment reduced circulating nonesterified fatty acid concentration in high-fat fed mice. Additionally, potential impairments in insulin signalling may have been minimized as indicated by conservation of the p-Akt/Akt ratio. Down-stream of glucose uptake, the administration of MSCs conferred protective effects to mitochondrial oxidative phosphorylation efficiency, maximal function and mitochondrial content. Conclusions: The experiments conducted in this dissertation provide insight into the utility of MSC transplantation as a metabolic therapy for the metabolic perturbations that characterize insulin resistance in the infarcted heart. Also, these studies propose potential mechanisms of action that lead to an enhanced energetic and functional state in the infarcted heart following MSC transplantation.
Open Access
Characterizing TOP1MT variants provides novel mechanistic insights into TOP1MT functions
(2022-01) Al Khatib, Iman; Shutt, Timothy; McGhee, James; Shearer, Jane
Mitochondria are organelles that have their own genome (mtDNA), which encodes 37 genes crucial for oxidative phosphorylation. Proper regulation of the mtDNA is critical for cellular functions, while impairment of its regulation can lead to disease. Mitochondrial topoisomerase 1 (TOP1MT) is a protein involved in mtDNA maintenance through its ability to bind mtDNA and relax supercoiled structures. In addition, TOP1MT is involved in the translation of mtDNA encoded proteins. To begin to understand how TOP1MT mechanistically performs these various roles, we characterized three candidate pathogenic variants (R198C, V338L and P193L) in the TOP1MT protein. We investigated how these variants affect the topoisomerase activity of TOP1MT, influencing mtDNA transcription and general mitochondrial health and function. We also examined the involvement of TOP1MT in replication and mtDNA protein translation. Combined with structural modelling, our functional characterization suggests an unexpected role for the nucleic acid binding domain of TOP1MT in controlling translation. Further, we detailed how these variants differ from each other and from wild-type protein. We demonstrated that the TOP1MT variants we investigated are not fully functional and are thus potential candidates to contribute to disease. During these studies, we also identified a novel role for TOP1MT, as its loss triggers mtDNA release into the cytosol and activation of cGAS-STING innate immune signaling. This novel finding was exciting, as the P193L variant was found in a family with autoimmune disorders. Interestingly, P193L could not rescue cGAS-STING activation in cells lacking TOP1MT, consistent with a role in autoimmune dysfunction. Overall, the molecular analysis we performed on these TOP1MT variants broadens our understanding of the different functions performed by TOP1MT, how its different roles are related, and the likelihood that TOP1MT is a disease gene.
Open Access
Developmental Programming of Obesity and Fatty Liver Disease in Offspring Exposed to Maternal Obesity and Dietary Intervention
(2017-12-15) Paul, Heather; Reimer, Raylene; Vogel, Hans; Shearer, Jane; Chelikani, Prasanth; Bell, Rhonda
Increased risk of developing obesity and related metabolic dysfunction has been linked to an adverse early-life environment as well as dysbiosis of gut microbiota, yet the precise molecular mechanisms involved in the establishment of disease susceptibility in offspring, and their link with the gut microbiota, remain elusive. This dissertation examines the impact of diet-induced maternal obesity on maternal metabolism and offspring susceptibility to obesity and fatty liver in a preclinical model of maternal diet-induced obesity and the potential protective effect of a maternal dietary fibre intervention. Specifically, the objectives of this thesis include 1) examining the maternal metabolic and gut microbial impact of prebiotic fibre supplementation in pregnant and lactating rats and the impact on offspring early-life obesity; 2) identifying the differences in metabolic and gut microbial adaptations to pregnancy and lactation in lean versus diet-induced obese rats; and 3) determining the potential of maternal prebiotic fibre supplementation to protect against later-life obesity and fatty liver in offspring following long-term exposure to an obesogenic diet. Our results first provide strong evidence in support of the hypothesis that maternal obesity and consumption of an obesogenic diet during pregnancy and lactation can program increased susceptibility to obesity and metabolic disease in offspring, the effects of which can be unmasked via long-term exposure to a high-fat/sucrose diet. This programming may be associated with specific shifts in maternal metabolism and gut microbial profiles. Second, we show that supplementation of a maternal high-fat/sucrose diet with the prebiotic fibre oligofructose alters maternal metabolism in a manner that attenuates early-life obesity in offspring, an outcome that is most likely mediated via prebiotic-induced shifts in the gut microbiota, in particular increased Bifidobacterium spp. abundance. Finally, we show that this supplementation attenuates the detrimental long-term programming effects of diet-induced maternal obesity, reducing hepatic steatosis and improving glucose tolerance and insulin sensitivity in adult offspring. Overall, maternal prebiotic fibre supplementation, in the context of maternal obesity, may represent an intervention during pregnancy and lactation that could help attenuate the propagation of obesity and related metabolic diseases across generations.
Open Access
Dietary Manipulation at Pre-Conception and During Development Influence Metabolism and Gut Microbiota in Rats
(2021-02-01) Chleilat, Fatima; Reimer, Raylene; Shearer, Jane; Arrieta, Marie-Claire
Background. Obesity is a complex disease, modulated by a plethora of factors, including gut microbiota, early post-natal nutrition, parental diet and epigenetics. Objective. This dissertation examines how dietary manipulation during the early post-natal period and during pre-conception alters metabolic, microbial and epigenetic outcomes in rats. Specifically, the objectives were to determine: 1) the impact of human milk oligosaccharide (HMO) supplementation on health status in weanling rats; 2) the impact of a paternal high protein (HP) diet on offspring metabolic health; 3) whether supplementation of a methyl donor cocktail (HF/S+M) before conception attenuates the deleterious metabolic and epigenetic effects of a paternal high fat/ sucrose diet intergenerationally; 4) the impact of paternal prebiotic consumption on microbial and metabolic outcomes in fathers and offspring. Methods. 1) Weanling male and female rats consumed 2’Fucosyllactose and 3’Sialylactose HMO-fortified diet for 8 weeks. Fathers consumed 2) a diet high in protein, 3) a high fat/ sucrose diet fortified with a methyl donor cocktail of betaine, choline, folic acid and vitamin B12, or 4) a high prebiotic fiber diet. All three paternal studies underwent their dietary intervention for 9 weeks. Offspring consumed a control diet for 13 weeks. Anthropometric, glucocentric and gut microbiota outcomes were measured in all four studies. Results. The primary findings include: HMO supplementation improved intestinal permeability, gut barrier function, and gut microbial composition in females while reducing weight gain and inflammatory cytokines in males; 2) Paternal HP diet reduced adiposity and altered epigenetic markers intergenerationally. Offspring had improved insulin sensitivity; 3) Paternal HF/S+M intake improved paternal reproductive outcomes and intergenerational gut microbial, epigenetic and metabolic outcomes; 4) Paternal prebiotic intake improved paternal gut microbiota with lesser effects in offspring. Conclusion. Our results provide evidence of early post-natal HMO supplementation and paternal HP, HF/S+M and prebiotic intake, as important modulators of gut microbial, epigenetic and metabolic outcomes.
Open Access
Dietary Manipulation of Gut Microbiota for Improvement of Metabolic Health
(2016) Bomhof, Marc; Reimer, Raylene; Shearer, Jane; Hittel, Dustin; Chelikani, Prasanth; Comelli, Elena
Background: Obesity is a highly complex disease state for which there remains a dearth of effective treatment and prevention strategies. An abundance of research now suggests that gut microbiota plays a role in the pathogenesis of obesity, making it a prime target for obesity management. Objective: This dissertation examines how dietary agents including prebiotics and probiotics, gut microbiota, and host physiology interact to affect metabolic health in obesity. Specifically, the objectives of this thesis include: 1) assess the individual and combined effects of a prebiotic and probiotic on metabolic health in obese rats; 2) determine the gut microbiota- dependent and -independent actions of the prebiotic oligofructose using a model of selective decontamination with antibiotics in obese rats; 3) examine the effectiveness of the prebiotic oligofructose for treatment of liver-biopsy confirmed non-alcoholic steatohepatitis (NASH) in a pilot clinical trial. Methods: Animal studies were conducted using diet-induced obese rats. Individuals with NASH were recruited by physicians from the Foothills Medical Centre. Body composition was measured with dual x-ray absorptiometry (DXA). Oral glucose tolerance tests (OGTTs) were conducted to measure glycemia. Markers of satiety, inflammation, and intestinal permeability were measured in blood. Gut microbiota was assessed using qPCR and 16S rRNA gene sequencing. Gene expression was measured using real time RT-PCR. Pre-post study liver biopsies were collected to assess histological changes in NASH. Results: The primary findings from our three study objectives were: 1) oligofructose, in comparison to Bifidobacterium animalis ssp. lactis BB-12, provides a more potent stimulus in reducing adiposity and modifying gut microbiota; 2) the ability of oligofructose to reduce adiposity and intestinal permeability is attenuated when Lactobacillus and Bifidobacterium growth is impeded with ampicillin in an animal model; 3) oligofructose supplementation improves histological measures of steatosis and has a tendency to decrease hepatocellular inflammation in individuals with NASH. Conclusion: Our results provide evidence for the role of prebiotics in correcting metabolic dysfunction in obesity. The findings from our pilot study provide the rationale for a larger-scale clinical trial assessing the effects of inulin type fructans and other prebiotics in NASH.
Open Access
Dietary Modulators of Gut Microbiota: Impact on Metabolic Health and Behaviour
(2019-07-03) Nettleton, Jodi; Reimer, Raylene; Shearer, Jane; Borgland, Stephanie
Background The ability of the gut microbiota to influence metabolic health and the potential to alter behaviour has been well-established. Therefore, targeting the gut microbiota to improve its’ composition through dietary agents is an attractive strategy to improve chronic diseases, like obesity, and impaired behaviours in neurodevelopmental conditions, like autism spectrum disorder. Objective This dissertation examines how dietary additives, including low-calorie sweeteners (LCS), and probiotics, prebiotics and synbiotics can alter metabolic, microbial and behavioural outcomes in rodents. Specifically, the objectives of this thesis were to: 1) assess the impact of maternal aspartame and stevia consumption on dams and offspring metabolism and gut microbiota; 2) determine the effects of long term low-dose stevia consumption in young male rats; 3) examine the impact of prebiotic, probiotic and synbiotic consumption on behaviours in an autism spectrum disorder mouse model. Methods 1) Diet-induced obese female rats consumed aspartame or stevia alongside a high fat diet during gestation and lactation; 2) Young male rats consumed stevia for nine-weeks; 3) Male BTBR mice were fed diets supplemented with prebiotic, probiotic, or synbiotic for three-weeks. In the first two studies, body composition, gut microbiota composition, and glucocentric and mesolimbic reward parameters were examined in dams, offspring, and male rats. In the third study, body weight and feces were measured/collected weekly and behaviour was tested at the end of treatment. Results The primary findings from our three study objectives were: 1) Maternal LCS consumption increased body weight and impaired glucocentric parameters in early life in offspring and changes were mediated by the gut microbiota; 2) Stevia intake reduced the relative abundance of cecal bifidobacteria taxa; 3) Probiotic consumption improved sociability and repetitive behaviour whereas prebiotic worsened sociability and had mixed effects on communicative variables, yet probiotic, prebiotic and synbiotic treated mice all had alterations in gut microbiota composition that indicated potential improved gut health. Conclusion Our results provide evidence for the role of low-calorie sweeteners in perpetuating obesity by altering gut microbiota composition and the potential for probiotic, prebiotic, and synbiotic to modulate behaviours associated with autism spectrum disorder.
Open Access
Early life antibiotic and prebiotic exposure: impact on gut microbiota, metabolism and obesity risk
(2019-09-18) Klančič, Teja; Reimer, Raylene A.; Pittman, Quentin J.; Shearer, Jane
Background: Obesity is a complex disease with multiple contributing factors including the gut microbiota. Antibiotics, when administered early in life, disrupt gut microbiota development and thereby increase the risk of obesity, whereas dietary agents such as prebiotics, reduce obesity risk via several pathways including microbiota-dependent mechanisms. Objective: This dissertation examines how antibiotics when administered with/without prebiotics, alter metabolic, microbial and anthropometric outcomes in rodents and humans. Specifically, the objectives were to: 1) assess the impact of indirect (maternal) antibiotic exposure with prebiotic co-administration on obesity risk in dams and their offspring; 2) determine the impact of direct antibiotic/prebiotic exposure in young rat pups on obesity risk and other metabolic parameters; 3) analyze available human birth cohort data from the All Our Families (AOF) study and explore the association between maternal antibiotic exposure and infant BMI z scores. Methods: 1) Sprague-Dawley rats consumed antibiotic and/or prebiotic during their 3rd week of pregnancy and lactation and their offspring were challenged with a high-fat high-sugar (HFS) diet from 9-17 weeks of age; 2) Rat pups were administered three pulses of azithromycin with/without prebiotic diet and weaned onto a HFS diet; 3) Using the AOF dataset, the association between infant BMI z score and maternal antibiotic use during pregnancy or during birth was examined. In the animal studies, body composition, gut microbiota composition, and metabolic outcomes were examined in dams and their offspring. In the human cohort, the association between antibiotic use during birth (intrapartum, n=1303)/during pregnancy (n=1943) and infant BMI z-score was investigated. Results: 1) Maternal antibiotic use during pregnancy/lactation impairs metabolism and postpartum weight loss in dams and increases obesity risk in their offspring, which was prevented with prebiotic co-administration; 2) Direct administration of azithromycin increased body weight and impaired insulin production/sensitivity. Prebiotic co-administration normalized the impairments; 3) Intrapartum antibiotic exposure might contribute to the development of child overweight/obesity at 1 year of age. Conclusion: Our results provide evidence for the ability of prebiotic co-administration with antibiotics to prevent metabolic impairments and obesity in rats. Future clinical trials should investigate whether this is also possible in humans.
Open Access
Early Life Dairy Exposure: Influence on the Gut Microbiota and Obesity Susceptibility
(2024-12-05) Hartslief, Micaela; Shearer, Jane; Reimer, Raylene; Thompson, Jennifer
Childhood obesity rates are increasing at a detrimental trajectory, leading to a serious health epidemic with related comorbidities that are likely to persist into adulthood (1,2). The causes of obesity are complex and influenced by a multitude of factors including diet, genetics and more recently dysbiosis of the gut microbiota (3,4). The gut microbiota is comprised of microorganisms residing in the gut, that have the ability to produce physiologically active substances such as vitamins and short-chain fatty acids and provide various health benefits through immune system regulation and removal of toxins (5). Mounting evidence suggests that dairy may play a protective role in obesity partially mediated through positive modulation of the gut microbiota (6,7). This study examined the role of dairy proteins, casein, whey and complete dairy (skim milk powder), and a plant-based alternative, soy, on gut microbiota composition, obesity susceptibility and insulin sensitivity. At weaning, 3-week-old pups (p=85), were randomized into 4 dietary protein intervention groups for 4-weeks: 1) complete dairy; 2) casein; 3) whey; 4) soy followed by a 5-week high-fat high-sucrose (HFHS) dietary challenge with the same proteins maintained. Microbial and metabolic outcomes assessed in this study included fecal microbial analysis (16s rRNA sequencing), body composition (NMR), glucose tolerance and insulin sensitivity. Dairy proteins compared to soy largely altered gut microbial profiles fostering improved metabolic function and enhanced insulin sensitivity. The impact on gut microbiota and metabolic results was protein dependent whereby early exposure to complete dairy demonstrated the most promising results improving body fat percentage and glucose tolerance while enriching beneficial probiotic microbial taxa, Lactobacillus in males while increasing Akkermansia in females. In contrast, following 5-week exposure to HFHS, there were limited differential effects on obesity, adiposity, sex hormones and glucose tolerance. Gut microbial profiles following HFHS dairy consumption, largely increased Bifidobacterium in males and maintained the increase of Akkermansia in females, however reduced alpha diversity. Taken together, dairy proteins play a significant role in positively modulating gut microbial profiles in a normal fat diet, fostering beneficial effects on body composition and glucose homeostasis.
Embargo
Effects of a Paternal Diet High in Animal Protein versus Plant Protein on Offspring Metabolic and Microbial Outcomes in a Rodent Model
(2023-11-17) Patterson, Riley; Reimer, Raylene; Shearer, Jane; Arrieta, Marie-Claire; Thompson, Jennifer
Obesity and type 2 diabetes are influenced by genetic and environmental factors, including diet. In addition to the well-known influence of maternal nutrition on offspring health, paternal diet has also been shown recently to program lifelong disease risk in their offspring. For instance, a paternal diet high in casein protein demonstrated numerous protective effects for their offspring including reduced body fat percentage, enhanced insulin sensitivity and higher satiety hormone levels compared to paternal high fat or control diets. Based on mounting evidence of this paternal influence, as well as dietary guidance to consume more plant products, the objective of this thesis was to examine the effects of animal versus plant protein on paternal and offspring health. Five-week-old male Sprague Dawley rats (n=36) were randomized into three dietary intervention groups for 8-11 weeks: 1) control AIN-93; 2) high animal casein protein (AP); and 3) high plant pea protein (PP). They were then mated. Offspring were challenged with a high fat/sucrose diet (HFD) from 10-16 weeks of age. Metabolic and microbial outcomes assessed in the fathers and offspring included body composition (DXA), glucose tolerance and insulin sensitivity (OGTT and ITT, respectively), gut microbial composition (16S rRNA sequencing), and gene expression (RT-PCR). The PP diet directly altered paternal hepatic microRNA expression and gut microbial profiles fostering improved metabolic functioning including enhanced insulin sensitivity and improved lipid metabolism and intestinal integrity depicted in decreased hepatic triglyceride and serum LPS levels, respectively. In contrast, adult offspring from fathers fed the AP diet exhibited increased adiposity, altered lipid metabolism, and dysregulated satiety hormones that were accompanied by altered miRNA expression and modified gut microbiota following 6-week exposure to a HFD. Overall, a paternal diet high in pea protein had numerous beneficial effects on the fathers’ metabolism and gut microbiota but had minimal effects on their offspring. Whereas a paternal diet high in animal protein during the preconception period had minimal effects on the fathers but programmed an increased predisposition to metabolic dysfunction in their adult offspring when unmasked by HFD exposure.
Open Access
Evaluation of Dietary Supplement Usage, Dietary Intakes, and Nutrition Knowledge in Clinical and Athletic Populations
(2022-06-27) Madden, Robyn F.; Shearer, Jane; Parnell, Jill A.; Reimer, Raylene; Legg, David.
Background: Nutrition is a broad scientific discipline under which dietary supplements fall. Dietary supplements can be defined as dietary ingredients intended to achieve a specific health and/or performance outcome. Utilization of dietary supplements differs between clinical and athletic populations; therefore, understanding the types, frequency, and reasons for use is pivotal to avoiding over- or under supplementing. Moreover, assessing dietary intakes and dietary patterns alongside dietary supplements helps ensure nutritional needs are being met. While the consumption of dietary supplements continues to increase, investigation of use, reasons for use, and evidence-based knowledge in support of these products, among many athletic and clinical populations, is lacking. Objective: This dissertation explores numerous nutritional concepts pertaining to para athletes, athletes with a spinal cord injury, and patients with mitochondrial disease. The specific objectives of this thesis are: 1) evaluate dietary intakes and supplement use in Canadian para athletes, 2) investigate dietary supplement use and reasons for use among Canadian wheelchair rugby athletes, 3) assess baseline sports nutrition knowledge levels of athletes with spinal cord injuries and coaches of para sport, and 4) explore dietary supplement use and dietary patterns followed in patients with mitochondrial disease. Methods: Four survey-based, cross-sectional studies were conducted to explore the above objectives. Specifically, 1) dietary intakes and supplement use were assessed in Canadian para athletes using three-day food records and a dietary supplement questionnaire; 2) dietary supplement use and reasons for use among Canadian wheelchair rugby athletes were collected via a dietary supplement questionnaire; 3) the Nutrition for Sport Knowledge Questionnaire was administered to assess knowledge levels among athletes with spinal cord injuries and coaches of para sport, and 4) dietary supplement use and dietary pattern information were evaluated among patients with mitochondrial disease using an electronic survey. Results: The primary findings from our study objectives were: 1) Canadian para athletes have several micronutrient inadequacies and uninformed use of specific supplements; 2) Canadian wheelchair rugby athletes highly utilize dietary supplements notably for medical and performance purposes; 3) athletes with spinal cord injuries and coaches of para sport demonstrated low-to-moderate sports nutrition knowledge across six nutrition categories, and 4) patients with mitochondrial disease relied heavily on a wide variety of dietary supplements while following specific dietary patterns for clinical symptom management.Conclusion: Our results provide evidence that dietary supplements are highly sought-after products across both clinical and athletic populations. Specifically, types and frequency of dietary supplements are implemented for a variety of reasons, depending on desired outcomes within each individual population. We also demonstrated the need for the development of dietary intake recommendations and evidence-based trials to better understand the effects of specific supplements on athletic performance and clinical disease management. Lastly, it is evident that nutrition knowledge is lacking in para athletic populations, highlighting the need for nutrition education.
Open Access
Experiences and perceived outcomes of a grocery gift card program for households at risk of food insecurity
(2022-01-28) Lee, Yun Yun; Olstad, Dana; Shearer, Jane; Elliott, Charlene; Campbell, David
Purpose: Food support programs, such as I Can for Kids (IC4K) in Calgary, Alberta, Canada, aim to reduce the prevalence and severity of household food insecurity by providing grocery gift cards (GGC) to low-income households with children. There are currently no qualitative studies that have explored whether and how GGC programs influence food access among food insecure households. I explored program recipients’ and program deliverers’ experiences and perceived outcomes of receiving or distributing GGC from IC4K. Method: I used qualitative descriptive methodology for this study. Data generation and analysis were guided by Freedman et al’s theoretical framework of nutritious food access. Fifty-four participants were purposively recruited. Semi-structured interviews were conducted between August and November 2020 with 37 program recipients who accessed IC4K’s GGC program and 17 program deliverers who facilitated it. Directed content analysis was used to analyze the data using a deductive-inductive approach. Codes were combined into subthemes and themes that summarized program recipients’ and deliverers’ experiences and perceived outcomes of receiving or distributing GGC, and suggestions to improve IC4K’s GGC program. Findings: Three themes were generated from the data. The first theme was related to how IC4K’s GGC program promoted a sense of autonomy and dignity among program recipients. The second theme was related to improved dietary patterns and food skills. The third theme was related to program logistical strengths and limitations, including the program’s impact on program deliverers’ connection with clients, their workload, experiences of differential access to GGC among recipients, and the importance of increasing program awareness to reach more food insecure households. Conclusion: IC4K’s GGC program enhanced recipients’ sense of autonomy and dignity and improved dietary patterns and food skills. Facilitating IC4K’s GGC program improved program deliverers’ connection with clients and reduced their overall workload. I also found experiences of differential access to GGC among recipients and the importance of increasing program awareness. I used my study findings to inform three recommendations to improve the experiences and perceived outcomes of future recipients who access IC4K’s GGC program: 1) increase the number of GGC; 2) establish concrete guidelines governing GGC distribution; and; 3) increase program awareness.
Open Access
Exploring Protein O-GlcNAcylation as a Novel Diagnostic Tool for Type II Mellitus and the Impact of Exercise on Cardiac Protein O-GlcNAcylation
(2014-05-16) Myslicki, Jason; Shearer, Jane; Belke, Darrell
The purpose of this study was to explore the sensitivity of O-linked β-N-acetylglucosamine (O-GlcNAc) in relation to various anthropometric and metabolic markers in healthy young adults and then to investigate how a chronic exercise regime affects this important post-translation signalling pathway in a Type II diabetic (T2DM) mouse model. Whole blood was collected from clinically healthy young adult males (n=24) and cardiac tissue was collected from diabetic (db/db) and control (db+) mice (n=9-10/group) that underwent six weeks of exercise or were designated sedentary. Western blot analysis was performed on all samples. Human whole blood exhibited greater sensitivity to Homeostatic Model of Assessment – Insulin Resistance (HOMA-IR) than Hemoglobin A1c (HbA1c) demonstrating its potential utility as a screening tool with strong diagnostic value. Six weeks of running wheel exercise did not alter protein O-GlcNAcylation in db/db or db+ mice. Protein O-GlcNAcylation is a valuable tool in assessing the efficacy of exercise in preventing T2DM.
Open Access
Exploring the Mechanism of Action of the Ketogenic Diet as a Therapeutic Intervention for medically refractory Infantile Spasms
(2023-12) Choudhary, Anamika; Scantlebury, Morris; Shearer, Jane; Teskey, Gordon Campbell
Objective: Infantile Spasms (IS) are a developmental, epileptic encephalopathy syndrome of infancy. It is characterized by epileptic spasms and a severe electroencephalogram abnormality, known as hypsarrhythmia, that can result in neurodevelopmental regression. Current anti-epileptic drugs are often deemed ineffective and can carry significant toxic side effects. The ketogenic diet (KD) is an alternative treatment for patients with drug resistant epilepsy, though its prospective validity and mechanism of action for IS remains unexplored. Methods: KD’s efficacy and mechanism of action was investigated using the triple-hit model of intractable IS. The spasms were induced using the triple-hit paradigm at P4 and the rat pups were then artificially reared and put on either the KD (4:1 fats:carbohydrate + protein) or a control-milk diet (CM; 1.7:1). Their behaviours were video-EEG recorded continuously from P4-12 for epileptic spasms and EEG analysis. Blood and urine ketones were collected at P4, P7 and P12. 31-phosphorus magnetic resonance spectroscopy (31P MRS), head-out plethysmography, and mitochondrial respirometry was also conducted to examine the KD’s mechanism of action. Results: The KD resulted in a ketosis observed both in the blood and urine. The KD led to a robust reduction in the spasm frequency, with approximately a 1.5-fold increase in the rate of survival. The KD resulted in an intracerebral acidosis as measured with 31P MRS. The respiratory profile of the KD-lesioned rats was significantly altered with slower, deeper, and longer breathing, resulting in decreased levels of expired CO2. Sodium bicarbonate supplementation, acting as a pH buffer, partially reversed the KD’s protective effects on spasm frequency. There was no effect of the diet on mitochondrial respiratory profiles measured in the liver and brain frontal cortex. Together, our results indicate that the KD produces its anticonvulsant effects through changes in respiration leading to intracerebral acidosis. Conclusion: These findings provide a novel understanding of the mechanisms underlying the anti-seizure effects of the KD in IS. Further research is required to determine whether the effects of the KD on breathing and intracerebral acid-base balance are seen in other pediatric models of epilepsy.
Open Access
Investigating a Mitochondrial Fission Inhibitor as a Therapeutic for Inflammatory Bowel Diseases
(2016) Xu, Warren; Shearer, Jane; McKay, Derek; Shutt, Timothy
Unbalanced mitochondrial dynamics exacerbates inflammation and is of interest for its possible role in the pathogenesis of inflammatory bowel disease (IBD). The current study utilized the P110 peptide drug, a selective inhibitor of mitochondrial fission, to investigate the relationship between mitochondrial dynamics and colitis. First, the functionality of the P110 peptide was verified in T84 colon epithelial cells in response to carbonyl cyanide m-chlorophenyl hydrazine (CCCP), a mitochondrial stressor. Second, the therapeutic potential of the P110 peptide was tested in a mouse model of IBD, chemically induced by dextran sodium sulfate (DSS). Treatment with P110 was found to reduce macroscopic symptoms of colitis and provides evidence that aberrant mitochondrial dynamics contribute to IBD. The results provide motivation for further investigation into the specific mechanisms by which mitochondrial dynamics impact IBD and a possible new therapeutic target for the treatment of IBD.
Open Access
Investigating the Consequences of DRP1 and Fis1 Mediated Mitochondrial Fission in Colitis: in Pursuit of a Novel Therapeutic Target for IBD
(2019-08-08) Goudie, Luke; Shearer, Jane; McKay, Derek Mark; Shutt, Timothy E.; Krawetz, Rowan
Since the 1980s, it has been hypothesized that inflammatory bowel disease (IBD) may be tied to insufficient energy production within the intestinal epithelium. In support of this theory, mitochondrial dysfunction has been noted in both IBD patient biopsies and the commonly used dextran sodium sulfate (DSS) murine colitis model. While relatively unexamined in human IBD or animal colitis contexts, evidence obtained from neurological and cardiovascular disease models has shown that unbalanced mitochondrial dynamics, favouring excessive mitochondrial fission, can promote mitochondrial dysfunction and disease. Furthermore, targeted inhibition of two mediators of this maladaptive process, dynamin related protein-1 (DRP1) and mitochondrial fission protein-1 (Fis1), by the novel peptide: P110, has shown therapeutic benefit in both neurodegenerative and cardiovascular disease models. Therefore, previous observations of mitochondrial dysfunction in IBD patients and murine colitis models may be tied to excessive mitochondrial fission, with inhibition of this process by P110 highlighting a potential target for IBD. To test this hypothesis, this study sought to: i) develop protocols for the assessment of mitochondrial function within a murine intestinal epithelial cell line (IEC4.1), ii) apply these protocols and other techniques to identify the consequences of DSS±P110 on IEC4.1 mitochondrial function, morphology and polarization state and iii) systemically deliver P110 in DSS and DNBS murine colitis models to determine if inhibition of excessive mitochondrial fission could exert anti-colitic benefit. Utilizing the developed O2k protocols, we found that DSS induced functional defects in IEC4.1 mitochondria, with P110 co-treatment mitigating some of the observed mitochondrial functional defects. Prophylactic and systemic administration of P110 was found to reduce macroscopic characteristics of both DSS and DNBS colitis in mice. Interestingly, these macroscopic improvements occurred despite limited changes to the assessed inflammatory markers, suggesting similar disease burden between DSS/DNBS+P110 and their disease counterparts. Results obtained from both the cellular and murine colitis models provides evidence that DRP1-Fis1 mediated mitochondrial fission is a feature of these colitis models and that targeting this interaction with P110 yields anti-colitic benefit. Therefore, this interaction could similarly be occurring in IBD patients and prove to be a novel target for future IBD therapeutics.
Open Access
Investigating the Effects of Probiotic Supplementation on the Gut-Brain Axis in Autism Spectrum Disorder
(2022-07) Pochakom, Angela; Shearer, Jane; Pittman, Quentin; Reimer, Raylene
Historically, the purpose of probiotic use in autism spectrum disorder (ASD) has been associated with alleviating co-morbid gastrointestinal symptoms. Recent studies have shown promise for the use of probiotics in modulating brain function to improve the behavioural symptoms of ASD through the microbiota-gut-brain axis. In the present study, we assessed the impact of two probiotic strains in mitigating autism-related symptomology in the BTBR T+ Itpr3tf/J mouse model of autism spectrum disorder (ASD). Male juvenile BTBR mice were randomized into 1) control, 2) Lr probiotic (1 x 109 CFU/mL Lacticaseibacillus rhamnosus HA-114), and 3) Ls probiotic groups (1 x 109 CFU/mL Ligilactobacillus salivarius HA-118) (n=18-21/group), receiving treatments in drinking water for 4-weeks. Gut microbiota profiling by 16S rRNA showed Lr, but not Ls supplementation, to increase microbial richness and phylogenetic diversity, with a rise in potential anti-inflammatory and butyrate-producing taxa. Assessing serum and brain metabolites, Lr and Ls supplementation produced distinct metabolic profiles, with Lr treatment elevating concentrations of potentially beneficial neuroactive compounds, such as 5-aminovaleric acid and choline. As mitochondrial dysfunction is often observed in ASD, we assessed mitochondrial oxygen consumption rates in the prefrontal cortex and hippocampus. No differences were observed for either treatment. Both Lr and Ls treatment reduced behavioural deficits in social novelty preference. However, no changes in hyperactivity, repetitive behaviour, and sociability were observed. Results show Lr to impart positive changes along the microbiota-gut-brain axis, exhibiting beneficial effects on selected behaviour, gut microbial diversity, and metabolism in BTBR mice.