Browsing by Author "Rytz, Chantal Louise"

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    Impact of a 6-month aerobic exercise intervention on oxidative stress in sedentary older adults
    (2018-12-17) Rytz, Chantal Louise; Poulin, Marc J.; Pialoux, Vincent; Hogan, David B.
    Background: Reactive oxygen species (ROS) play integral roles in cell signalling and systemic processes and are tightly controlled through workings of antioxidants. An imbalance in this relationship can lead to oxidative stress. Completion of regular exercise can mitigate oxidative stress, strengthen antioxidant capacity and improve oxidative stress- associated conditions, such as metabolic syndrome (MetS) and decreased cerebrovascular function. However, there is limited knowledge as to how the aging population with and without MetS compare in terms of changes in markers of oxidative stress and antioxidant profiles with an aerobic exercise intervention, and the effect these changes in have on cerebrovascular function. Objective: We aimed to assess the effects of a 6-month aerobic exercise intervention on markers of oxidative stress and antioxidant capacity in older, sedentary yet healthy adults, and to determine how MetS status affected these exercise-induced changes. Further, as an exploratory measure, we aimed to assess the association between changes in markers of oxidative stress and antioxidant capacity and measures of cerebrovascular function. Design: Blood samples from 206 participants (mean age=66.8 ± SE=6.4 years, 104 females) pre-, midway, and post-intervention were assessed for markers of oxidative stress (advanced oxidation protein products [AOPP; malondialdehyde [MDA]; 3-nitrotyrosine [3-NT]) and antioxidant capacity (superoxide dismutase [SOD]; uric acid [UA]; ferric- reducing ability of ṗ lasma [FRAP]; nitric oxide metabolites [NOx]; catalase). Maximal aerobic capacity (VO2max), anthropometric and demographic information was also collected. Repeated measures linear mixed models adjusted for covariates were used to evaluate changes in markers of oxidative stress and antioxidant capacity across the exercise intervention. Factors represented by changes in markers of oxidative stress and antioxidant status were used in a linear regression analysis to assess the potential association between oxidative stress and cerebrovascular function. Results: There was a significant effect of the exercise intervention on decreasing levels of AOPP (p=0.004) however, neither MetS status (p=0.214) nor sex (p=0.437) modified the effect. Individuals with MetS had significantly higher levels of AOPP (p<0.001), MDA (p<0.001), FRAP (p=0.03) and UA (p=0.003) compared to those without. Men possessed significantly higher levels of AOPP (p=0.001), FRAP (p<0.001), catalase (p=0.013) and UA (p<0.001) compared to women. Interestingly, the effect of MetS status on FRAP and 3-NT was highly dependent on sex. Further, exercise-induced changes in measures of oxidative stress and antioxidant status were significantly associated with post-intervention measures of cerebrovascular function at rest and submaximal exercise. Conclusion: These results indicate that MetS may blunt exercise-induced improvements in oxidative stress and that changes in markers of oxidative stress and antioxidant status may impact exercise-induced cerebrovascular improvements in older, healthy adults.
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    The Cardiovascular Implications of Gender-Affirming Estrogen Therapy Use in Transgender Women
    (2024-04-24) Rytz, Chantal Louise; Ahmed, Sofia Bano; Saad, Nathalie; Dumanski, Sandra Marie; Ronksely, Paul Everett; Raj, Satish R.; Somayaji, Ranjani
    Cardiovascular disease is a leading cause of death globally, with transgender and gender diverse (TGD) individuals, and particularly transgender women (sex assigned male at birth who identify as women) facing significant rates of cardiovascular-related morbidity and mortality. While uncertainties exist regarding the potential contribution of gender-affirming estrogen therapy in the increased cardiovascular risk noted in this population, there remains a critical evidence gap in understanding how factors such as serum estradiol levels, sex assigned at birth, and gender identity impact cardiovascular risk. Therefore it was the objective of this thesis to determine the cardiovascular implications of gender-affirming hormone therapy in transgender women, which was explored from various angles through conducting three independent studies. Our first study provides an understanding of the association between serum estradiol and cardiovascular-related mortality, adverse cardiovascular events and cardiovascular related risk factors using a systematic review and meta-analysis approach. We determined that the rate of serum estradiol change across the use of gender-affirming estrogen therapy may influence cardiovascular risk factors, which may have implications for clinical cardiovascular outcomes. Using a cross-sectional approach, our second study evaluated the impact of gender identity and sex assigned at birth on measures of vascular hemodynamics and arterial stiffness in transgender women as compared to cisgender women and men. Our findings underscore the importance of considering gender identity in addition sex assigned at birth when evaluating measures of cardiovascular health and risk. Our final study addressed the major methodological limitation with retrospective studies within the TGD population by generating and validating numerous case-definitions to identify both transgender women and men in routinely-collected healthcare data in Alberta, Canada. By linking numerous administrative data sources and testing against a reference standard of self-identified gender identity, a combination of using sex assigned in provincial registry and exogenous hormone dispensations or TGD-related billing codes were the most sensitive at identifying TGD individuals, and were employed to approximate both prevalence and incidence per 100,000 person-years, providing a first-ever assessment of the TGD population within Alberta. Despite recent advances and calls for the incorporation of both sex and gender into health research and clinical care, gaps in the understanding of cardiovascular health in transgender women remain. Our findings highlight numerous factors that may be implicated in cardiovascular health and risk in the transgender women population. This thesis may inform areas for further interventions aimed at improving cardiovascular health, mitigating cardiovascular disease risk, and exploring clinical cardiovascular outcomes in transgender women.