Spencer D Proctor

Spencer D Proctor
University of Alberta | UAlberta · Alberta Diabetes Institute (ADI)

PhD

About

173
Publications
18,420
Reads
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4,758
Citations
Additional affiliations
July 2004 - present
University of Alberta
Position
  • Professor (Full)
January 2003 - June 2004
University of Alberta
Position
  • CJ Martin Research Fellow NHMRC (Atherosclerosis & Diabetes)
February 2001 - December 2002
Curtin University
Position
  • Research Fellow (Lipoprotein Metabolism and Atherosclerosis)

Publications

Publications (173)
Article
Full-text available
Although dairy intake has been shown to have a neutral or some beneficial effect on major cardiometabolic risk factors, the impact of dairy, and especially dairy fat, on immune function remains to be investigated. To understand the effect of consuming dairy fat on cardiometabolic risk factors and immune function, we used an established low birthwei...
Article
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Obesity has emerged as a leading global health concern. It is characterized by chronic low-grade inflammation, which impairs insulin signaling, lipid metabolism and immune function. Recent findings from animal and clinical studies have begun to elucidate the underlying mechanisms of immune dysfunction seen in the context of obesity. Here, we provid...
Article
Full-text available
High-fat diets (HFD) have been shown to induce substantial shifts in intestinal microbial community composition and activity which are associated with adverse metabolic outcomes. Furthermore, changes in microbial composition are affected by fatty acid composition; saturated, monounsaturated (MUFA), and industrial trans fats (iTFA) adversely affect...
Article
Stroke affects primarily aged and co-morbid people, aspects not properly considered to date. Since angiogenesis/vasculogenesis are key processes for stroke recovery, we purposed to determine how different co-morbidities affect the outcome and angiogenesis/vasculogenesis, using a rodent model of metabolic syndrome, and by dynamic enhanced-contrast i...
Article
Introduction: Cardiovascular disease (CVD) originates in childhood and risk is exacerbated in obesity. Mechanisms of the etiologic link between early adiposity and CVD-risk remain unclear. Postprandial or non-fasting dyslipidemia is characterized by elevated plasma triglycerides (TG) and intestinal-apolipoprotein(apo)B48-remnants following a high-...
Article
Full-text available
Context Adolescents with polycystic ovary syndrome (PCOS) have increased incidence of cardiometabolic risk factors including dyslipidemia. Atherogenic apolipoprotein (apo) B-lipoprotein remnants are associated with increased cardiovascular disease (CVD) risk. Objective The aim of this study was to determine the concentrations of fasting plasma apo...
Article
Background and aims Cardiovascular disease (CVD) begins in youth, and is exacerbated by obesity and metabolic syndrome. Apolipoprotein (Apo)B-remnant cholesterol is considered a primary contributor to CVD risk. Fasting plasma apoB48 can be used as a biomarker of intestinal remnant cholesterol as well as postprandial dyslipidemia. In adults, elevate...
Article
Ruminant meat (RM) is an excellent source of high-quality protein, B vitamins and trace minerals and plays an important role in global food and nutrition security. However, nutritional guidelines commonly recommend reduced intake of RM mainly because of its high saturated fatty acid (SFA) content, and more recently because of its perceived negative...
Article
Low birth weight (LBW) and postnatal nutrition are risk factors for adult metabolic diseases. However, the interactions between LBW, diet, and intestinal lipid absorption and secretion leading to adult metabolic disease remain unclear. The current study determined the impact of LBW on intestinal lipid and carbohydrate metabolism under both control...
Article
Arterial stiffness plays a causal role in development of systolic hypertension. 20-hydroxyeicosatetraeonic acid (20-HETE), a cytochrome P450 (CYP450)-derived arachidonic acid metabolite, is known to be elevated in resistance arteries in hypertensive animal models and loosely associated with obesity in humans. However, the role of 20-HETE in the reg...
Article
The intestine is involved in whole-body lipid and cholesterol homeostasis and secretes lipoproteins containing apolipoprotein(Apo)B48 anddiscreteApoA-I into themesenteric lymph.Thelymphatic systemhasbeen proposed to have a significant role in the reverse cholesterol transport pathway associated with HDL-ApoA-I. In conditions of insulin resistance (...
Article
Large artery stiffness is a causal factor in development of systolic hypertension. 20-hydroxyeicosatetraeonic acid (20-HETE), a cytochrome CYP450-derived arachidonic acid metabolite, is known to be elevated in resistance arteries in hypertensive animal models and in obesity in humans, but the role of 20-HETE in regulation of large artery remodeling...
Article
Invited speaker- CSAS symposium: Healthy animals producing healthy foods. Let food be thy medicine” is a quote attributed to Hippocrates. Moving a link down the food it might be more appropriate to say “Let feed be medicine for thy food and thy food be medicine for you”. We live in times when links between diet and health are being recognized more...
Article
Full-text available
CONTEXT PCSK9 mediates the degradation of the low-density lipoprotein receptor (LDLR) thereby increasing plasma low density lipoprotein cholesterol (LDL-C). Variations in the PCSK9 gene that are associated with loss-of-function (LOF) of PCSK9 result in a greater expression of hepatic LDLR, lower concentrations of LDL-C, and protection from cardiova...
Article
The present study was designed to determine if feeding steers extruded flaxseed and hay (25 and 75%; DM basis) together as a total mixed ration (TMR), or sequentially (non-TMR) would result in different enrichments of polyunsaturated fatty acids (PUFA) and their biohydrogenation intermediates (BHI) in beef adipose tissues [subcutaneous (SC) vs peri...
Article
The objective of the present experiment was to determine if carcass quality and fatty acid profiles of longissimus thoracis (LT) and hamburger would be affected by feeding steers extruded flaxseed on its own followed by hay (non-TMR) compared to when hay and extruded flaxseed were fed together (TMR). Forty-eight steers in six pens were assigned to...
Article
Full-text available
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease involved in the regulation of LDL receptor (LDLR) expression and apolipoprotein B lipoprotein cholesterol metabolism. Hepatic PCSK9 protein expression, activity, and secretion have been shown to affect cholesterol homeostasis. An upregulation of hepatic PSCK9 protein leads t...
Article
Thirty percent of the world population is diagnosed with metabolic syndrome. High-fat/high-sucrose (HF/HS) diet (Western diet) correlates with metabolic syndrome prevalence. We characterized effects of the HF/HS diet on vascular (arterial stiffness, vasoreactivity, and coronary collateral development) and cardiac (echocardiography) function, oxidat...
Article
Coronary collateral growth (CCG) is impaired in metabolic syndrome (MetS). microRNA-145 (miR-145-Adv) delivery to our rat model of metabolic syndrome (JCR) completely restored and neutrophil depletion significantly improved CCG. We determined whether low endogenous levels of miR-145 in MetS allowed for elevated production of 20-hydroxyeicosatetraen...
Article
Transient, repetitive myocardial ischemia (RI)-induced coronary collateral growth (CCG) is impaired in metabolic syndrome patients and animal models. Endothelial cell (EC) dysfunction and chronic inflammation are hallmarks of metabolic syndrome. We showed that while in normal animals (SD), RI induces transient infiltration of monocytes, associated...
Article
Hawthorn is a widely used herbal alternative medicine for the treatment of various cardiovascular diseases. However, the attributed health benefits, purported to be due to the presence of phenolic compounds, may depend on both the specific species and plant part. Studies to date investigating effects of hawthorn on heart disease(s) have used well-d...
Article
Context: Atherosclerotic vascular disease begins in childhood and while progression is multifactorial, obesity in early life is an important risk factor for its development. Objective: To determine if fasting apoB48 (relative to classic lipid markers), is elevated with increasing central adiposity over time in a cohort of Canadian children with...
Article
Full-text available
Over the past 20 years, a growing amount of evidence supports the role of microbes and an imbalanced microbiota in inflammatory bowel disease (IBD). While many reviews have been written on the microbiota in IBD, few have considered how they fulfil the Koch's postulates. In this review, we consider how the Koch's postulates might be modified so that...
Article
Background: The response-to-retention hypothesis for atherosclerosis describes subendothelial retention of apolipoprotein B-containing lipoproteins mediated by proteoglycans (PG). Further we know that diabetes is also associated with both increased circulating chylomicron remnants and remodeling of proatherogenic PGs. We have recently reported anti...
Article
Extruded flaxseed and ground hay [25% and 75%; dry matter (DM) basis] were fed in a total mixed ration (TMR) or sequentially (non-TMR) to three pens of eight crossbred steers per diet. At 112 d, erythrocytes from non- TMR steers had 65% more vaccenic acid (trans 11-18:1) than TMR steers (P < 0.05).
Article
Full-text available
The main dietary sources of trans fatty acids are partially hydrogenated vegetable oils (PHVO), and products derived from polyunsaturated fatty acid biohydrogenation (PUFA-BHP) in ruminants. Trans fatty acid intake has historically been associated with negative effects on health, generating an anti-trans fat campaign to reduce their consumption. Th...
Article
Catheterization of the intestinal lymph trunk in neonatal pigs is a technique allowing for the long-term collection of large quantities of intestinal (central) efferent lymph. Importantly, the collection of central lymph from the intestine enables researchers to study both the mechanisms and lipid constitutes associated with lipid metabolism, intes...
Article
Full-text available
Vaccenic acid (VA), the predominant ruminant-derived trans fat in the food chain, ameliorates hyperlipidemia yet mechanisms remain elusive. We investigated whether VA could influence tissue endocannabinoids (EC) by altering the availability of their biosynthetic precursor, arachidonic acid (AA) in membrane phospholipids (PL). JCR:LA-cp rats were as...
Article
Full-text available
White adipocytes are known to function as endocrine organs by secreting a plethora of bioactive adipokines which can regulate cardiac function including the development of hypertrophy. We determined whether adipose tissue conditioned medium (ATCM) generated from the epididymal regions of normal rats can affect the hypertrophic response of cultured...
Article
Scope: Trans-11 vaccenic acid (VA) is a fatty acid produced by ruminants entering the human food supply through meat and dairy products, which appears not to have the health risks associated with industrially produced trans-fatty acids. In this study, we investigated the effect of VA on insulin secretion in vivo in rats and in vitro in human and r...
Poster
Introduction: The response-to-retention hypothesis suggests proteoglycan-lipoprotein interaction is the initiating step in atherosclerosis. Diabetic-dyslipidemia is associated with increased circulating remnant lipoproteins as well as increased arterial atherogenic proteoglycans. chP3R99 is a monoclonal antibody that recognizes glycosaminoglycan (G...
Article
Full-text available
Abstract BACKGROUND: Childhood obesity is an important early predictor of adult obesity and associated comorbidities. Common forms of obesity are underpinned by both environmental and genetic factors. However, the rising prevalence of obesity in genetically stable populations strongly suggests that contemporary lifestyle is a premier factor to the...
Article
Full-text available
Polycystic ovary syndrome (PCOS) is one of the most common endocrine-metabolic disorders in women of reproductive age characterized by ovulatory dysfunction, hyperandrogenism, and cardiometabolic risk. The overweight-obese PCOS phenotype appears to have exacerbated reproductive dysfunction and cardiometabolic risk. In overweight-obese adult women w...
Article
Choline is a precursor to phosphatidylcholine (PC), a structural molecule in cellular membranes that is crucial for cell growth and function. PC is also required for the secretion of lipoprotein particles from liver and intestine. Choline requirements are increased during lactation when maternal choline is supplied to the offspring through breast m...
Article
Introduction: Emerging evidence shows that the proximal small intestine secretes cholesterol into the intestinal lumen via the trans-intestinal cholesterol excretion (TICE) pathway. It is thought TICE can contribute up to 30-40% of fecal neutral sterol excretion. Plasma apoB containing lipoproteins are known to donate cholesterol to the TICE pathwa...
Article
Full-text available
Coronary collateral growth (CCG) is impaired in metabolic syndrome. miR-21 is a pro-proliferative and anti-apoptotic microRNA (miR), which we showed to be elevated in metabolic syndrome. Here we investigate whether impaired CCG in metabolic syndrome involved miR-21-mediated aberrant apoptosis. Normal (SD) and metabolic syndrome (JCR) rats underwent...
Article
It has been postulated that insulin resistance results from the accumulation of cytosolic lipid metabolites (i.e. diacylglycerol/ceramide) that impede insulin signaling and impair glucose homeostasis. De novo ceramide synthesis is catalyzed via serine palmitoyl transferase-1 (SPT1). Our aim was to determine if de novo ceramide synthesis plays a rol...
Article
Full-text available
Hamburger is the most consumed beef product in North America, but lacks in nutritional appeal due to its high fat content and high proportion of saturated fatty acids (SFA). Objectives of the present study were to improve the FA profiles of hamburgers made with perirenal fat (PRF) and subcutaneous fat (SCF) when feeding steers different diets along...
Conference Paper
Full-text available
Background: Phosphatidylethanolamine N-methyltransferase (Pemt) is the only de novo pathway for phosphatidylcholine (PC) synthesis in mammals; as such, Pemt-/- mice are chronically choline-deficient. Phospholipids (PL) play a fundamental role in VLDL formation, secretion and clearance. Pemt deficiency dramatically reduces atherosclerosis developmen...
Article
Full-text available
Inadequate cell proliferation is considered a major causative factor for impaired coronary collateral growth (CCG). Proangiogenic growth factors (GFs) stimulate cell proliferation, but their administration does not promote CCG in patients. These GFs are increased in patients with metabolic syndrome and in animal models, where CCG is impaired. Here,...
Article
Full-text available
We hypothesized the CB1 receptor (CB1R) and leptin receptor (ObR) operate synergistically to modulate metabolic, neuro-endocrine and behavioral responses of animals exposed to a survival challenge (food restriction and wheel running). Obese-prone (OP) JCR:LA-cp rats, lacking functional leptin receptors (ObR), and Lean-prone (LP) JCR:LA-cp rats (int...
Article
INTRODUCTION: Niacin is the oldest hypolipidemic drug that effectively lowers plasma triglycerides whilst increasing HDL-C concentration. However the mechanism of action of niacin still remains elusive. Emerging evidence shows that in addition to the liver, the intestine also contributes to whole body HDL metabolism. The effect of insulin resistanc...
Article
INTRODUCTION: There is emerging epidemiological data that supports a causative role for remnant cholesterol in atherosclerotic and CVD progression. We have shown that hepatic (apoB100) and intestinal (apoB48) lipoproteins may have disparate ‘egress’ and retention properties. Additionally we have reported that insulin resistance (IR) increases the a...
Article
Full-text available
Background: Phosphatidylethanolamine N-methyltransferase (Pemt) is the only de novo pathway for phosphatidylcholine (PC) synthesis in mammals; as such, Pemt -/- mice are chronically choline-deficient. PEMT deficiency dramatically reduces atherosclerosis development in LDL receptor (LDLR) knockout mice. This atheroprotective effect is believed to be...
Article
Objective: Statins are widely used for the treatment of hyperlipidemia to reduce cardiovascular disease (CVD) risk. Intriguingly, recent reports suggest that whilst statins are effective in reducing hepatic cholesterol synthesis, they in turn may up-regulate intestinal cholesterol absorption. The direct effects and/or mechanisms of this phenomenon...
Article
Full-text available
Unlabelled: Pioglitazone was associated with increased hazard for surgical or percutaneous lower extremity revascularization in patients with diabetes in a large clinical trial, but this clinical finding has not been adequately explored in animal models. We hypothesized that pioglitazone would decrease hypoxia-inducible factor 1α (HIF-1α)-dependen...
Article
Full-text available
The current study evaluated the composition and relationships of polyunsaturated fatty acid biohydrogenation products (PUFA-BHP) from the perirenal (PRF) and subcutaneous fat (SCF) of yearling steers fed a 70 % grass hay diet with concentrates containing either sunflower-seed (SS) or flaxseed (FS). Analysis of variance indicated several groups or f...
Article
Full-text available
Dietary choline is required for proper structure and dynamics of cell membranes, lipoprotein synthesis, and methyl-group metabolism. In mammals, choline is synthesized via phosphatidylethanolamine N-methyltransferase (Pemt), which converts phosphatidylethanolamine to phosphatidylcholine. Pemt(-/-) mice have impaired VLDL secretion and developed fat...
Article
Full-text available
We hypothesised that hypothalamic feeding-related neuropeptides are differentially expressed in obese-prone and lean-prone rats and trigger overeating-induced obesity. To test this hypothesis, in the present study, we measured energy balance and hypothalamic neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) mRNA expressions in male JCR:LA-cp rat...
Article
Introduction The intestine secretes discrete fractions of triglyceride (TG) rich apoB-chylomicrons (CM) and HDL particles into mesenteric lymph. Insulin resistance (IR) is associated with overproduction of intestinal CM however, the effect of IR on intestinal HDL secretion remains unknown. Niacin has been shown to reduce plasma TG while increasing...
Article
Full-text available
The definition of trans-fatty acids (TFA) was established by the Codex Alimentarius to guide nutritional and legislative regulations to reduce TFA consumption. Currently, conjugated linoleic acid (CLA) is excluded from the TFA definition based on evidence (primarily preclinical studies) implying health benefits on weight management and cancer preve...