Alexandra M Williams

Alexandra M Williams
University of British Columbia - Vancouver | UBC · International Collaboration on Repair Discoveries (ICORD)

PhD

About

29
Publications
6,498
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
344
Citations
Introduction
Alexandra M Williams currently works at the International Collaboration on Repair Discoveries (ICORD), University of British Columbia - Vancouver. Alexandra does research in Cardiac Physiology, Autonomic Control of the Cardiovascular System and Neurology. Their current research focuses on the cardiac consequences of spinal cord injuries, and cardio-centric approaches to clinical management of the spinal cord injured patient.

Publications

Publications (29)
Article
Key points: Cervical spinal cord injury (C-SCI) alters both the cardiac and respiratory systems, however little is known as to how these systems interact following injury. Here, we manipulated inspiratory or expiratory intrathoracic pressure (ITP) to mechanistically test the role of the respiratory pump on circulatory function in highly-trained in...
Article
Objective: . Chronic high-level spinal cord injury (SCI) results in a complex phenotype of cardiovascular consequences, notably impairments to cardiac contractile function and baroreflex control of blood pressure. Recently, our group has demonstrated that hemodynamic management targeting the heart (i.e. dobutamine, DOB), rather than standard vasop...
Article
Full-text available
Spinal cord injury chronically alters cardiac structure and function and is associated with increased odds for cardiovascular disease. Here, we investigate the cardiac consequences of spinal cord injury on the acute-to-chronic continuum, and the contribution of altered bulbospinal sympathetic control to the decline in cardiac function following spi...
Article
Haemoconcentration can influence hypoxic pulmonary vasoconstriction (HPV) via increased frictional force and vasoactive signalling from erythrocytes, but whether the balance of these mechanism is modified by the duration of hypoxia remains to be determined. We performed three sequential studies: (i) at sea level, in normoxia and isocapnic hypoxia w...
Article
The high-altitude maladaptation syndrome known as chronic mountain sickness (CMS) is characterized by polycythemia and is associated with proteinuria despite unaltered glomerular filtration rate. However, it remains unclear if indigenous highlanders with CMS have altered volume regulatory hormones. We assessed N-terminal pro-B-type natriuretic pept...
Article
Background Spinal cord injury (SCI) leads to a loss of descending motor and sympathetic control below the level of injury (LOI), which ultimately results in chronically altered cardiovascular function and remodeling. While supervised, laboratory-based exercise training can generate cardiovascular adaptations in people with SCI, it is unknown whethe...
Article
Key points: Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and likely plays an influential role in the modulation of hypoxic pulmonary vasoconstriction. It is uncertain whether iron regulation is altered in lowlanders during either 1) ascent to high altitude, or 2) following partial acclimatization, when compa...
Article
Full-text available
Chronic high-thoracic and cervical spinal cord injury (SCI) results in a complex phenotype of cardiovascular consequences, including impaired left ventricular (LV) contractility. Here, we aim to determine whether such dysfunction manifests immediately post-injury, and if so, whether correcting impaired contractility can improve spinal cord oxygenat...
Preprint
Full-text available
Chronic high-thoracic and cervical spinal cord injury (SCI) results in a complex phenotype of cardiovascular consequences, including impaired left-ventricular contractility. Here, we sought to determine whether such dysfunction manifests immediately post-injury, and if so, whether correcting impaired contractility can improve spinal cord oxygenatio...
Article
Key points: We have developed a novel porcine model of high-thoracic midline contusion spinal cord injury (SCI) at the T2 spinal level. We describe this model and the ensuing cardiovascular and neurohormonal responses, and demonstrate it is an efficacious model for studying clinically relevant cardiovascular dysfunction post-SCI. We demonstrate th...
Article
Full-text available
In contrast to Andean natives, high-altitude Tibetans present with a lower hemoglobin concentration that correlates with reproductive success and exercise capacity. Decades of physiological and genomic research have assumed that the lower hemoglobin concentration in Himalayan natives results from a blunted erythropoietic response to hypoxia (i.e.,...
Article
Background: Left ventricular (LV) twist mechanics are augmented with both acute and chronic hypoxemia. Although the underlying mechanisms remain unknown, sympathetic activation and a direct effect of hypoxemia on the myocardium have been proposed, the latter of which may produce subendocardial dysfunction that is masked by larger subepicardial tor...
Article
Key points: The effect of combined inspiratory and expiratory muscle training on resting and reflexive cardiac function as well as exercise capacity in individuals with cervical spinal cord injury (SCI) is presently unknown. Six weeks combined inspiratory and expiratory muscle training enhances both inspiratory and expiratory muscle strength in hi...
Article
Objective Conduct a meta-analysis to determine the impact of traumatic spinal cord injury (SCI) on echocardiographic measurements of left ventricular (LV) structure and function. Methods MEDLINE and Embase were used for primary searches of studies reporting LV echocardiographic data in individuals with SCI. Of 378 unique citations, 36 relevant ful...
Article
Background: Left ventricular (LV) twist mechanics differ between males and females during acute physiological stress, which may be partly mediated by sex differences in autonomic control. While males appear to have greater adrenergic control of LV twist, the potential contribution of vagal modulation to sex differences in LV twist remains unknown....
Article
It remains unclear if the human coronary vasculature is inherently sensitive to changes in arterial PO2and PCO2or if coronary vascular responses are the result of concomitant increases in myocardial O2consumption/demand (MVO2). We hypothesized that the coronary vascular response to PO2and PCO2would be attenuated in healthy men when MVO2was attenuat...
Article
Volume loading increases left ventricular (LV) stroke volume (LVSV) through series interaction but may paradoxically reduce LVSV in the presence of large increases in right ventricular (RV) afterload due to direct ventricular interaction (DVI). RV afterload is often increased in COPD as a result of pathological changes to respiratory mechanics, nam...
Article
Background: Sex differences in LV mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV hemodynamics. Accordingly, this study aimed to investigate sex differences in LV mechanics with altered adrenergic stimulation achieved thr...
Article
COPD is associated with dynamic lung hyperinflation (DH), increased pulmonary vascular resistance (PVR) and large increases in negative intrathoracic pressure (nITP). The individual and interactive effect of these stressors on left ventricular (LV) filling, emptying and geometry, and the role of direct ventricular interaction (DVI) in mediating the...
Article
Background-Compared to males, females have smaller left ventricular (LV) dimensions and volumes, higher ejection fractions (EF), and higher LV longitudinal and circumferential strain. LV twist mechanics determine ventricular function, and are preload-dependent. Therefore, the sex differences in LV structure and myocardial function may result in dif...
Article
Our aim was to quantify the end-tidal-to-arterial gas gradients for O2 (PET-PaO2) and CO2 (Pa-PETCO2), during a CO2 reactivity test in order to determine their influence on the cerebrovascular (CVR) and ventilatory (HCVR) response in subjects with (PFO+, n=8) and without (PFO-, n=7) a patent foramen ovale (PFO). We hypothesized that 1) the Pa-PETCO...
Article
During step-transitions in work rate (WR) within the moderate-intensity (MOD) exercise domain, pulmonary O2 uptake (VO2p) kinetics are slowed and VO2p gain (ΔVO2p/ΔWR) is greater when exercise is initiated from an elevated metabolic rate. High-intensity interval training (HIT) has been shown to speed VO2p kinetics when step-transitions to MOD exerc...
Article
Full-text available
A compelling idea in cognitive neuroscience links motor control and action observation. Recent work supports the idea that a link exists not just between action observation and action planning, but between observation and motor learning. Several studies support the idea that cortical regions that underlie active motor learning also play a role in m...
Article
Full-text available
Integrating community-based health and social care has grabbed international attention as a way of addressing the needs of aging populations while contributing to health systems' sustainability. However, integrating initiatives in different jurisdictions work (or do not work) within very various institutional and structural dynamics. The question i...
Article
We are very grateful to the editors of HealthcarePapers for making this timely journal edition possible, and to our distinguished contributors for sharing their valuable insights on aging at home from local, national and international perspectives. While starting from different points and using different approaches, each contributor has articulated...

Network

Cited By