T Dylan Olver

T Dylan Olver
University of Saskatchewan | U of S · Department of Biomedical Sciences WCVM

PhD

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99
Publications
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Introduction
Skills and Expertise

Publications

Publications (99)
Article
Full-text available
Background While intra-arrest echocardiography can be used to guide and monitor chest compression quality, it is not currently feasible on the scene of out-of-hospital cardiac arrests. Rapid and automated sonographic localization of the heart may provide first-responders guidance to an optimal area of compression without requiring them to interpret...
Article
Full-text available
The purpose of this study was to determine if differences in functional connectivity strength (FCS) with age were confounded by vascular parameters including resting cerebral blood flow (CBF0), cerebrovascular reactivity (CVR), and BOLD-CBF coupling. Neuroimaging data were collected from 13 younger adults (24 ± 2 years) and 14 older adults (71 ± 4...
Article
Background: Chronic hyperglycemia promotes excessive production of endothelial reactive oxygen species (ROS), which may impair nitric oxide (NO) signaling, a hallmark of vascular disfunction. How maturation and exercise training influence this process in the cerebrovasculature has yet to be explored. The purpose of this study was to examine the ro...
Article
Objective: The reactivity of conduit vessels such as the brachial artery is important in influencing arterial diameter, and subsequently, blood flow. Flow-mediated dilation (FMD) measures vessel reactivity. The increase in shear stimuli from transient arterial occlusion enhances arterial diameter in an endothelial-dependent manner, and this is tho...
Article
Introduction: The standard chest compression (SCC) position for cardiopulmonary resuscitation (CPR) is the centre of the chest and typically central to the aortic root. An alternative left ventricle chest compression (LVCC) position may facilitate superior global blood flow. We tested the hypothesis that, consistent with improved ETCO2 (indicative...
Article
Ischemic heart disease is a leading cause of death, often resulting from heart failure caused by myocardial infarction. Diabetic cardiomyopathy is increasingly problematic clinically, with the combination of metabolic syndrome and chronic inflammation greatly increasing the risk for both coronary and cerebral vascular disease. Follistatin-like 1 (F...
Article
Introduction: Aging is associated with increased sympathetic nerve activity (SNA) and reduced vasoreactivity. Cold pressor test (CPT) increases SNA and may thus counteract exercise-induced local vasodilation. We tested the hypothesis that older adults would exhibit less vasoreactivity following acute rhythmic handgrip (HG) exercise coupled with CP...
Article
Introduction: Competing influences regulate blood flow control in the brain. In the skeletal muscle vasculature, purinergic ATP signaling attenuates α1- adrenergic and peptidergic-induced vascular smooth muscle contraction (i.e., phenomenon referred to as functional sympatholysis); however, whether this occurs in the cerebrovasculature remains unk...
Article
Irregular heartbeats are often considered benign in isolation, but individuals who experience them frequently have a higher prevalence of cerebrovascular and/or cognitive associated disorders How irregular heartbeats affect blood pressure and cerebral hemodynamics in healthy and cardiovascular disease patients, those with and without reduced ejecti...
Article
Full-text available
The study of vascular regulation often omits important information about the elastic properties of arteries under conditions of pulsatile flow. The purpose of this study was to examine the relationship between muscle sympathetic nerve activity (MSNA), vascular bed compliance, and peripheral blood flow responses in humans. We hypothesized that incre...
Article
Full-term low birthweight (LBW) offspring exhibit peripheral vascular dysfunction in the postnatal period; however, whether such impairments extend to the cerebrovasculature remains to be elucidated. We used a swine model to test the hypothesis that LBW offspring would exhibit cerebrovascular dysfunction at later stages of life. Offspring from 14 s...
Article
Full-text available
Individuals with heart failure (HF) frequently present with comorbidities, including obesity, insulin resistance, hypertension, and dyslipidemia. Many patients with HF experience cardiogenic dementia, yet the pathophysiology of this disease remains poorly understood. Using a swine model of cardiometabolic HF (Western diet+aortic banding; WD-AB), we...
Article
Heart failure (HF) patients with deteriorating right ventricular (RV) structure and function have a nearly two-fold increased risk of death compared to those without. Despite the well-established clinical risk, few studies have examined the molecular signature associated with this HF condition. The purpose of this study was to integrate morphologic...
Article
The small heat shock protein 20 (HSPB6) emerges as a potential upstream mediator of autophagy. Although autophagy is linked to several clinical disorders, how HSPB6 and autophagy are regulated in the setting of heart failure (HF) remains unknown. The goal of this study was to assess activation of the HSPB6 and its association with other well-establ...
Article
Full-text available
Background Evidence indicates that birth weight and neonatal nutrition have lifelong effects. Animal models are required to improve our understanding of these factors. Objectives We aimed to develop and validate a swine model of birth weight and neonatal undernutrition. Methods At birth, a total of 112 piglets were identified as low (LBW; 1.22 ±...
Article
Insulin modulates vasomotor tone through vasodilator and vasoconstrictor signaling pathways. The purpose of the present work was to determine whether insulin-stimulated vasoconstriction is a pathophysiological phenomenon that can result from a combination of persistent insulin signaling, suppressed PI3K activation and an ensuing relative increase i...
Article
Full-text available
Post-menopausal women with heart failure (HF) frequently exhibit cardiogenic dementia. Using a pre-clinical swine model of post-menopausal HF, we recently demonstrated that experimental menopause (ovariectomy; OVX) and HF (6-month cardiac pressure overload/aortic banding; AB) independently altered cerebral vasomotor control and together impaired co...
Article
Aims Heart failure (HF) is associated with increased large conduit artery stiffness and afterload resulting in stiffening of the coronary arteries. Perivascular adipose tissue (PVAT) and advanced glycation end products (AGE) both promote arterial stiffness, yet the mechanisms by which coronary PVAT promotes arterial stiffness and the efficacy of ex...
Article
Full-text available
The development of new treatments for heart failure lack animal models that encompass the increasingly heterogeneous disease profile of this patient population. This report provides evidence supporting the hypothesis that Western Diet−fed, aortic-banded Ossabaw swine display an integrated physiological, morphological, and genetic phenotype evocativ...
Article
Effective treatments preventing brain neuroinflammatory diseases are lacking. Resistance-exercise training (RT) ameliorates mild cognitive impairment (MCI), a forerunner to neuroinflammatory diseases. However, few studies have addressed the molecular basis by which RT abates MCI. Thus, experiments were performed to identify some molecular changes o...
Article
We present the hypothesis that exercise-induced hyperemia, perhaps through vascular shear stress, represents an important factor responsible for the effects of physical activity (PA) on vascular insulin sensitivity. Specifically, we postulate PA involving the greatest amount of skeletal muscle mass and the greatest central neural recruitment maximi...
Article
Vascular insulin resistance often precedes endothelial dysfunction in type 1 diabetes mellitus. Strategies to limit vascular dysfunction include intensive insulin therapy (4–9 mM) and aerobic training. To avoid the risk of hypoglycaemia, individuals often prescribed conventional insulin therapy (9–15 mM) and participate in resistance training. In a...
Article
Key point: It has been postulated that increased blood flow-associated shear stress on endothelial cells is an underlying mechanism by which physical activity enhances insulin-stimulated vasodilation. This report provides evidence supporting the hypothesis that increased shear stress exerts insulin-sensitizing effects in the vasculature and this e...
Article
Increased peripheral conduit artery stiffness has been shown in patients with heart failure (HF) with preserved ejection fraction. However, it is unknown whether this phenomenon extends to the coronary vasculature. HF with preserved ejection fraction may be driven, in part, by coronary inflammation, and inhibition of the enzyme DPP-4 (dipeptidyl-pe...
Article
Full-text available
Purpose Recent clinical data suggest an increasing prevalence of obesity and type 2 diabetes in adolescents, placing them at high risk of developing diabetic retinopathy during adult working years. The present study was designed to characterize the early retinal and microvascular alterations in young Ossabaw pigs fed a Western diet, described as a...
Article
Conventional treatments have failed to improve the prognosis of heart failure with preserved ejection fraction (HFpEF) patients. Thus, the purpose of this study was to determine the therapeutic efficacy of chronic interval exercise training (IT) on BKCachannel-mediated coronary vascular function in heart failure. We hypothesized chronic interval ex...
Article
In rodents, experimentally-induced ovarian hormone deficiency increases adiposity and adipose tissue (AT) inflammation, which is thought to contribute to insulin resistance and increased cardiovascular disease risk. However, whether this occurs in a translationally-relevant large animal model remains unknown. Herein, we tested the hypothesis that o...
Article
Background: Impaired microvascular insulin signaling may develop prior to overt indices of microvascular endothelial dysfunction and represent an early pathological feature of adolescent obesity. Using a translational porcine model of juvenile obesity, we tested the hypotheses that in the early stages of obesity development, impaired insulin signa...
Article
Full-text available
Background Postmenopausal women represent the largest cohort of patients with heart failure with preserved ejection fraction, and vascular dementia represents the most common form of dementia in patients with heart failure with preserved ejection fraction. Therefore, we tested the hypotheses that the combination of cardiac pressure overload (aortic...
Article
Introduction: Heart failure with preserved ejection fraction (HFpEF) is clinically characterized by an increased incidence in females and many comorbidities including type 2 diabetes (T2D) and obesity. Animal models accurately representing clinical HFpEF are lacking; thus, the purpose of this study was to examine left ventricular (LV) mechanics in...
Article
It is increasingly recognized that obesity is a risk factor for microvascular disease, i.e. results in structural and functional changes in the microvasculature. This review aims to describe how obesity impacts the microvasculature of visceral adipose tissue, skeletal muscle, heart, brain, kidneys and lungs. These changes involve endothelial dysfun...
Article
Full-text available
This exploratory study assessed the pattern of closed-loop baroreflex resetting using multi-logistic-curve analysis. Operating point gain and ranges of RR-interval (RRI) and systolic blood pressure (SBP) are derived to examine how these relate to sympathetic activation. Sustained low-intensity isometric handgrip exercise, with a period of post-exer...
Article
Full-text available
Type 2 diabetes (T2D) increases skeletal fragility and fracture risk; however, the underlying mechanisms remain to be identified. Impaired bone vascular function, in particular insulin-stimulated vasodilation and blood flow is a potential, yet unexplored mechanism. The purpose of this study was to determine the effects of T2D on femoral biomechanic...
Article
Full-text available
Streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) decreases trabecular bone volume and bone strength in rodents. The current study investigated the potential protective effects of aerobic endurance training (AET) on bone in STZ-induced T1DM young adult rats. Sixty-four 8-week-old male Sprague-Dawley rats were randomly divided into 4 grou...
Article
This study tested the hypotheses that obesity-induced decrements in insulin-stimulated cerebrovascular vasodilation would be normalized with acute endothelin-1a receptor antagonism, and treatment with a physical activity intervention restores vasoreactivity to insulin through augmented nitric oxide synthase (NOS)-dependent dilation. Otsuka Long-Eva...
Article
Sympathetic outflow is modified during acute homeostatic stress through increased firing of low-threshold axons, recruitment of latent axons, and synaptic delay modifications. However, the role of central mechanisms versus peripheral-reflex control over sympathetic recruitment remains unknown. Here, we examined sympathetic discharge patterns during...
Article
In response to acute physiological stress, the sympathetic nervous system modifies neural outflow through increased firing frequency of lower-threshold axons, recruitment of latent sub-populations of higher-threshold axons, and/or acute modifications of synaptic delays. Aging and coronary artery disease (CAD) often modify efferent muscle sympatheti...
Article
Full-text available
Interval sprint exercise performed on a manually propelled treadmill, where the hands grip the handle bars, engages lower and upper limb skeletal muscle, but little is known regarding the effects of this exercise modality on the upper limb vasculature. We tested the hypotheses that an acute bout of sprint exercise and 6 weeks of training induces br...
Article
Exercise intolerance and poor exercise capacity are associated with aging, diabetes, cognitive impairment, and premature death. In this issue of Cell Metabolism, Mera et al. (2016) report that osteocalcin improves endurance exercise performance by enhancing myofiber fuel uptake and utilization, while osteocalcin supplementation reverses the age-ind...
Article
Full-text available
The etiology of insulin resistance in Type 1 Diabetes (T1D) is unknown, however it affects approximately 20% of T1D patients. Intramyocellular lipids (IMCL) have been identified as a mechanism of insulin resistance. We examined skeletal muscle of T1D rats to determine if alterations in lipid metabolism were evident and whether aerobic exercise trai...
Article
Full-text available
Background: Cognitive impairment in the setting of heart failure with preserved ejection fraction remains poorly understood. Using aortic-banded miniature swine displaying pathological features of human heart failure with preserved ejection fraction, we tested the hypothesis that increased carotid artery stiffness and altered carotid blood flow co...
Article
An acute bout of exercise elicits a rapid, potentially deleterious, reduction in blood glucose in patients with type 1 diabetes mellitus (T1DM). In the current study, we examined whether a 10-week aerobic training program could alleviate the rapid exercise-associated reduction in blood glucose through changes in the glucoregulatory hormonal respons...
Article
Full-text available
Indices of cardiovascular autonomic neuropathy (CAN) in experimental models of Type 1 diabetes mellitus (T1DM) are often contrary to clinical data. Here, we investigated whether a relatable insulin-treated model of T1DM would induce deficits in cardiovascular (CV) autonomic function more reflective of clinical results and if exercise training could...
Chapter
Compared with resting conditions, during incremental exercise, cardiac output in humans is elevated from ~5 to 25Lmin-1. In conjunction with this increase, the proportion of cardiac output directed toward skeletal muscle increases from ~20% to 85%, while blood flow to cardiac muscle increases 500% and blood flow to specific brain structures increas...
Conference Paper
Nutrition is a fundamental component influencing athletic performance. To date, the majority of research has focused on the ergogenic effects of carbohydrate, fluid or electrolyte supplementation. In contrast, products such as BioSteel High Performance Sports Drink (BioSteel; a low carbohydrate, branched chain amino acid supplement [BCAA]) are avai...
Article
Type 2 diabetes (T2D) alters capillary hemodynamics, causes capillary rarefaction in skeletal muscle and alters endothelial and vascular smooth muscle cell phenotype. These changes contribute to altered blood flow responses to physiological stimuli such as; exercise and insulin secretion. T2D-induced microvascular dysfunction impairs glucose and in...
Article
What is the topic of this review? This review highlights the importance of increased vascular insulin sensitivity for maintaining glycaemic control and cardiovascular health. What advances does it highlight? We discuss the role of habitual physical activity in modulating vascular actions of insulin. Type 2 diabetes and cardiovascular disease common...
Article
Full-text available
Aim: We investigated the cardiorespiratory response during acute sprint interval exercise (SIE; 4 x 30 sec maximal efforts, each separated by 4 min recovery) vs. continuous endurance exercise (CEE; 30 min) at 70% VO2max. Methods: Oxygen consumption (VO2) and heart rate were measured in 8 males (age: 23±2.3 y, height: 181±6.4 cm, body mass: 78±8....
Article
Full-text available
A cumulative effect of reduced energy intake, increased oxygen consumption, and/or increased lipid oxidation could explain the fat loss associated with sprint interval exercise training (SIT). This study assessed the effects of acute sprint interval exercise (SIE) on energy intake, subjective appetite, appetite-related peptides, oxygen consumption,...
Article
The purpose of this study was to determine whether bidirectional flow exists in the sciatic vasa nervorum. Images obtained using high-frequency colour Doppler ultrasound in duplex imaging mode (Vevo 2100) were studied retroactively. In Fig. 1 (left panel; rat 1), the colour Doppler signal and flow-velocity waveforms are indicative of pulsatile flow...
Article
Full-text available
2000 m time-trail performance, aerobic capacity, and anaerobic capacity were assessed in 16 trained oarsmen after sprint interval training (SIT) replaced a portion of an endurance-based training program (EBTSIT) vs an endurance-based program alone (EBTAlone). EBTSIT involved 10 SIT sessions over 4 weeks, in addition to 12 continuous exercise sessio...