• Role of acute exercise-induced brain-derived neurotrophic factor on beta-site amyloid precursor protein cleaving enzyme 1 and amyloid precursor protein processing in the brain

      Baranowski, Bradley John; Applied Health Sciences Program
      Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) is the rate limiting enzyme in the pathway responsible for beta-amyloid production, a pathological feature of Alzheimer’s Disease (AD). Exercise has been shown to reduce BACE1 activity, although the mechanisms responsible are unknown. Exercise has also been shown to increase brain-derived neurotrophic factor (BDNF) content and signalling, however whether this neurotrophic factor mediates the effects of exercise on BACE1 regulation requires further investigation. C57BL/6J male mice were placed on a low (LFD) or high fat diet (HFD) for 10-weeks. Following the intervention, the mice either remained sedentary or underwent an acute bout of treadmill running. Mice were euthanized and the prefrontal cortex and hippocampus were collected for analysis. The remaining sedentary mice (n=24) were used for an explant experiment where the tissue was directly treated with BDNF. The HFD reduced BDNF content in the hippocampus, however, an acute bout of exercise was able to significantly increase BDNF content in the prefrontal cortex. We further demonstrated that direct treatment with BDNF results in reductions in BACE1 activity in the prefrontal cortex. This novel finding demonstrates that BDNF can reduce BACE1 activity, independent of an exercise stimulus. Moreover, this finding shows for the first time, that there is a direct link between BDNF signalling and BACE1 regulation in this region of the brain. This highlights the viability of using exercise and BDNF to modulate BACE1 activity as a potential therapeutic intervention, without the negative consequences of drug-induced inhibitions.
    • Role of family eating practices on daily nutrient intakes, dietary patterns and measures of body composition in peri-adolescents

      Hajna, Samantha; Applied Health Sciences Program (Brock University, 2011-03-08)
      Although family eating practices (FEPs) playa role in the formation of eating practices in children, there is a lack of evidence regarding the role of FEPs on obesity (DB) risk. The purpose of this thesis was to assess the role of child, mother 'and father eating practices (CEPs; MEPS; FaEPs) on nutrient intakes, dietary patterns and body composition. Data were collected on approximately 2,400 peri-adolescents (s250 with complete covariate data). Dietary patterns were assessed using scores that reflected how closely participants followed DASH and Health Canada (HC) recommendations. In girls, poor CEPs, MEPs and FaEPs were associated with increased BMI and risk of overweight and poor dietary patterns according to DASH, and DASH and HC, respectively. In boys, poor CEPs and FaEPs were associated with increased monounsaturated and trans fat, and Vitamin C intakes, respectively. These findings suggest FEPs are associated with DB risk, particularly in girls.
    • The role of intrapartum intravenous therapy and method of delivery on newborn weight loss : challenging the 7% rule

      Sheehan, Kim.; Applied Health Sciences Program (Brock University, 2009-02-16)
      It is common practice to initiate supplemental feeding in newborns if body weight decreases by 7-10% in the first few days after birth (7-10% rule). Standard hospital procedure is to initiate intravenous therapy once a woman is admitted to give birth. However, little is known about the relationship between intrapartum intravenous therapy and the amount of weight loss in the newborn. The present research was undertaken in order to determine what factors contribute to weight loss in a newborn, and to examine the relationship between the practice of intravenous intrapartum therapy and the extent of weight loss post-birth. Using a cross-sectional design with a systematic random sample of 100 mother-baby dyads, we examined properties of delivery that have the potential to impact weight loss in the newborn, including method of delivery, parity, duration of labour, volume of intravenous therapy, feeding method, and birth attendant. This study indicated that the volume of intravenous therapy and method of delivery are significant predictors of weight loss in the newborn (R2=15.5, p<0.01). ROC curve analysis identified an intravenous volume cut-point of 1225 ml that would elicit a high measure of sensitivity (91.3%), and demonstrated significant Kappa agreement (p<0.01) with excess newborn weight loss. It was concluded that infusion of intravenous therapy and natural birth delivery are discriminant factors that influence excess weight loss in newborn infants. Acknowledgement of these factors should be considered in clinical practice.
    • The Role of Membrane Lipid Composition on Sarco(endo)plasmic Reticulum Calcium ATPase Function in Rat Soleus Muscle

      Trojanowski, Natalie S.; Applied Health Sciences Program
      Sarco(endo)plasmic reticulum calcium ATPase (SERCA) is a transmembrane protein whose function is regulated by its immediate lipid environment (annulus). The composition of the annulus is currently unknown or it’s susceptibility to a high saturated fat diet (HSFD). Furthermore it is uncertain if HSFD can protect SERCA from thermal stress. The purpose of the study was to determine SERCA annular lipid composition, resulting impact of a HSFD, and in turn, influence on SERCA activity with and without thermal stress. The major findings were annular lipids were shorter and more saturated compared to whole homogenate and HSFD had no effect on annular lipid composition or SERCA activity with and without thermal stress. Both average chain length and unsaturation index were positively correlated with SERCA activity with and without thermal stress. These findings suggest that annular lipid composition is different than whole homogenate and its composition appears to be related to SERCA function.
    • The Role of Membrane Lipid Composition on Skeletal Muscle Damage in the Rodent Model of Duchenne Muscular Dystrophy

      Zibamanzarmofrad, Maral; Applied Health Sciences Program
      Duchenne muscular dystrophy is a X-linked muscle disease, which leads to alterations in membrane phospholipid fatty acid (FA) composition and skeletal muscle damage. Increased membrane saturated FA in muscular dystrophy may suggest its association with increased susceptibility (as being the cause or consequence) to muscle damage. It was hypothesised that increased saturation is positively correlated to increased muscle damage. Correlations were hypothesized to be greater in extensor digitorum longus (EDL) at 20 weeks compared to soleus (SOL) at 10 weeks in dystrophin deficient (mdx) mice. Increased saturation was correlated to damage in EDL at both 10 and 20 weeks, with stronger correlations at 10 weeks. The results suggest that membrane PL FA composition may be associated with damage through two possible means. Increased saturation may be a cause or consequence of membrane damage. Association of membrane composition with eccentric induced damage has underscored the importance of saturated PL FA compositions in damage to dystrophic myofibres.
    • The role of molecular, clinical and socioeconomic factors in the long-term survival of axillary node negative breast cancer patients

      Brenner, Darren.; Applied Health Sciences Program (Brock University, 2008-06-29)
      The overall objective of this study was to investigate factors associated with long-term survival in axillary node negative (ANN) breast cancer patients. Clinical and biological factors included stage, histopathologic grade, p53 mutation, Her-2/neu amplification, estrogen receptor status (ER), progesterone receptor status (PR) and vascular invasion. Census derived socioeconomic (SES) indicators included median individual and household income, proportions of university educated individuals, housing type, "incidence" of low income and an indicator of living in an affluent neighbourhood. The effects of these measures on breast cancer-specific survival and competing cause survival were investigated. A cohort study examining survival among axillary node negative (ANN) breast cancer patients in the greater Toronto area commenced in 1 989. Patients were followed up until death, lost-to-follow up or study termination in 2004. Data were collected from several sources measuring patient demographics, clinical factors, treatment, recurrence of disease and survival. Census level SES data were collected using census geo-coding of patient addresses' at the time of diagnosis. Additional survival data were acquired from the Ontario Cancer Registry to enhance and extend the observation period of the study. Survival patterns were examined using KaplanMeier and life table procedures. Associations were examined using log-rank and Wilcoxon tests of univariate significance. Multivariate survival analyses were perfonned using Cox proportional hazards models. Analyses were stratified into less than and greater than 5 year survival periods to observe whether known markers of short-tenn survival were also associated with reductions in long-tenn survival among breast cancer patients. The 15 year survival probabilities in this cohort were: for breast cancerspecific survival 0.88, competing causes survival 0.89 and for overall survival 0.78. Estrogen receptor (ER) and progesterone receptor (PR) status (Hazard Ratio (HR) ERIPR- versus ER+/PR+, 8.15,95% CI, 4.74, 14.00), p53 mutation (HR, 3.88, 95% CI, 2.00, 7.53) and Her-2 amplification (HR, 2.66, 95% CI, 1.36, 5.19) were associated with significant reductions in short-tenn breast cancer-specific survival «5 years following diagnosis), however, not with long-term survival in univariate analyses. Stage, histopathologic grade and ERiPR status were the clinicallbiologieal factors that were associated with short-term breast cancer specific survival in multivariate results. Living in an affluent neighbourhood (top quintile of median household income compared to the rest of the population) was associated with the largest significant increase in long-tenn breast cancer-specific survival after adjustment for stage, histopathologic grade and treatment (HR, 0.36, 95% CI, 0.12, 0.89).
    • The role of physical activity and perceived adequacy on cardiorespiratory fitness in children with developmental coordination disorder

      Silman, Adi.; Applied Health Sciences Program (Brock University, 2009-02-16)
      Evidence suggests that children with developmental coordination disorder (DCD) have lower levels of cardiorespiratory fitness (CRF) compared to children without the condition. However, these studies were restricted to field-based methods in order to predict V02 peak in the determination of CRF. Such field tests have been criticised for their ability to provide a valid prediction of V02 peak and vulnerability to psychological aspects in children with DCD, such as low perceived adequacy toward physical activity. Moreover, the contribution of physical activity to the variance in V02 peak between the two groups is unknown. The purpose of our study was to determine the mediating role of physical activity and perceived adequacy towards physical activity on V02 peak in children with significant motor impairments. This prospective case-control design involved 122 (age 12-13 years) children with significant motor impairments (n=61) and healthy matched controls (n=61) based on age, gender and school location. Participants had been previously assessed for motor proficiency and classified as a probable DCD (p-DCD) or healthy control using the movement ABC test. V02 peak was measured by a progressive exercise test on a cycle ergometer. Perceived adequacy was measured using a 7 -item subscale from Children's Selfperception of Adequacy and Predilection for Physical Activity scale. Physical activity was monitored for seven days with the Actical® accelerometer. Children with p-DCD had significantly lower V02 peak (48.76±7.2 ml/ffm/min; p:50.05) compared to controls (53.12±8.2 ml/ffm/min), even after correcting for fat free mass. Regression analysis demonstrated that perceived adequacy and physical activity were significant mediators in the relationship between p-DCD and V02 peak. In conclusion, using a stringent laboratory assessment, the results of the current study verify the findings of earlier studies, adding low CRF to the list of health consequences associated with DCD. It seems that when testing for CRF in this population, there is a need to consider the psychological barriers associated with their condition. Moreover, strategies to increase physical activity in children with DCD may result in improvement in their CRF.
    • The Role of Pyruvate Dehydrogenase Kinase-4 in Post-Exercise Glycogen Recovery

      Herbst, Eric; Applied Health Sciences Program (Brock University, 2011-09-09)
      The pyruvate dehydrogenase (PDH) complex regulates the oxidation of carbohydrates in mammals. Decreased activation of PDH following exhaustive exercise may aid the resynthesis of glycogen through increased activity of PDH kinase-4 (PDK4), one of four kinases that decrease the activity of the PDH complex. The purpose of this study was to examine the role of PDK4 in post-exercise glycogen resynthesis. Wild-type (WT) and PDK4-knockout (PDK4-KO mice) were exercised to exhaustion and were sampled at rest (Rest), at exercise exhaustion (Exh), and after two-hours post-exercise (Rec). Differences in feeding post-exercise led to the addition of a PDK4-KO group, pair-fed (PF) with WT mice. Glycogen fully recovered in all Rec groups in muscle however remained low in the PF group in liver. Flux through PDH was elevated in PDK4-KO muscle with feeding and low in the PF group in both tissues. This suggests PDK4 may fine-tune flux through PDH during exercise recovery.
    • The role of self-presentation in adolescent health risk behaviours

      Roth, Kelly.; Applied Health Sciences Program (Brock University, 2006-05-19)
      Self-presentation has been identified as playing a key role in the perfonnance of various potentially hazardous health behaviours such as substance abuse, eating disorders and reckless behaviours (Leary, Tchividjian, & Kraxberger, 1994; Martin & Leary, 2001; Martin, Leary, & O'Brien, 2001). The present study investigated the role of selfpresentation on adolescent health-risk behaviours. Specifically, this study examined the prevalence of adolescent identified health-risk behaviours rooted in self-presentational motives in youths aged 13-18 years. The current study also identified the specific images associated with these behaviours desired by youth, and the targets of these behaviours. Also, the relationship between these behaviours, and several trait measures (social physique anxiety, public-self consciousness, fear of negative evaluations, selfpresentational efficacy) of self-presentation were examined. Finally, the gender differences in health risk behaviours and self-presentational concerns were examined. Participants in the present study were 96 adolescent students, 34 male and 62 female, recruited from various private schools across Southern Ontario. Students ranged in age from 13 to 18 years for both males (M age = 15.81 years, SD = 1.49) and females (M age = 14.89 years, SD = 1.17) and ranged from grades 8 through 13. Results of the current study suggested that Canadian adolescents between the ages of 13 and 18 years participated in health risk behaviours for self-presentational purposes. Drinking alcohol, skipping school, and performing stunts and dares were identified as the most common health risk behaviours performed for self-presentational purposes by both males and females. Appearing fun and cool were the most commonly reported desired images while appearing brave and mature were the least reported. The most desired target group cited was same sex friends, followed by other sex friends. Trait measures of self-presentational concerns identified females as being higher in public self-consciousness, and social physique anxiety than males. Males were found to be higher in self-presentational efficacy than females. The total number of health risk behaviours was predicted by selfpresentational efficacy and social physique anxiety for males, and social physique anxiety for females. Findings of the current study suggest that Canadian adolescents' health risk behaviours are rooted, in part, in self-presentational motives. Thus far, an educational approach to health interventions has been favoured and/or adopted by teachers, health promoters, and educators (Jessor, 1992). Implications of the current study suggest that although educational interventions are beneficial in presenting the associated risks with certain activities and/or behaviours, one reason this type of approach may be ineffective in changing adolescent behaviour over the long run is that it does not address the strong and prominent influences of interpersonal motives on health damaging behaviour. It is evident that social acceptance and public image are of importance to adolescents, and the desire to make the "right" impression and to achieve peer approval and acceptance often override health and safety concerns (Jessor, 1992). Thus, a self-presentational approach focusing on changing the images associated with the behaviours may be more successful at deterring adolescent health risk behaviours.
    • The roles of ERK1/2 and PI3K in abnormal vascular functions in angiotensin II-infused hypertensive rats

      Ding, Lili.; Applied Health Sciences Program (Brock University, 2005-06-29)
      Background: Ang II plays a major role in cardiovascular regulation. Recently, it has become apparent that vascular superoxide anion may play an important role in hypertension development. Treatment with antisense NAD(P)H oxidase or SOD decreased BP in Ang II-infused rats. Wang et al recently reported mice which lack one of the subunits of NAD(P)H oxidase developed hypertension at a much lower extent when compared to the wild type animals infused with Ang II, indicating that superoxide anion contributes to elevation in BP in the Ang II-infused hypertensive model. In the Ang II-infused hypertensive model, altered reactivity of blood vessels is often associated with the elevation of systolic blood pressure. We have observed abnormal tension development and impaired endothelium-dependent relaxation in the isolated aorta of Ang II-infused and DOCA-salt hypertensive rats. Recently, several other cellular signal molecules, including ERK1I2 and PI3K, have been determined to play important roles in the regulation of smooth muscle contraction and relaxation. ERKl/2 and PI3K pathways are also reported to contribute to Ang II induced cell growth, hypertrophy, remodeling and contraction. Moreover, these signaling pathways have shown ROS-sensitive properties. Therefore, the aim of the present study is to investigate the roles of ERKl12 and PI3K in vascular oxidative stress, spontaneous tone and impaired endothelium relaxation in Ang II-infused hypertensive model. Hypothesis: We hypothesize that the activation of ERKl12 and PI3K are elevated in response to an Ang II infusion for 6 days. The elevated activation of phospho-ERKl/2 and PI3K mediated the increased level of vascular superoxide anion, the abnormal vascular contraction and impaired endothelium-dependent vascular relaxation in Ang II-infused hypertensive rats. Methods: Vascular superoxide anion level is measured by lucigenin chemiluminescence. Spontaneous tone and ACh-induced endothelium-dependent relaxation was measured by isometric tension recording in organ chamber. The activity of ERK pathway will be measured by its Western blot of phosphorylation of ERK. PI3K activity was evaluated indirectly by Western blot of the phosphorylation of PDKl, a downstream protein of PI3K signaling pathway. The role of each pathway was also addressed via comparing the responses to the specific inhibitors. Results: Superoxide anion was markedly increased in the isolated thoracic aorta from Ang II-infused rats. There was spontaneous tone developed in rings from Ang II-induced hypertensive but not sham-operated normotensive rats. ACh-induced endothelium-dependent relaxation function is impaired in Ang II-infused hypertensive rats. Superoxide dismutase and NAD(P)H oxidase inhibitor, apocynin, inhibited the abnormal spontaneous tone and ameliorated impaired endothelium-dependent relaxation. The expression of phopho-ERKII2 was enhanced in Ang II-infused rats, indicating the activity of ERK1I2 could be increased. MEK1I2 inhibitors, PD98059 and U126, but not their inactive analogues, SB203580 and U124, significantly reduced the vascular superoxide anion in aortas from Ang II-infused rats. The MEK1I2 inhibitors reduced the spontaneous tone and improved the impaired endothelium-dependent relaxation in aorta of hypertension. These findings supported the role of ERKII2 signaling pathway in vascular oxidative stress, spontaneous tone and impaired endothelium-dependent relaxation in Ang II-infused hypertensive rats. The amount of phospho-PDK, a downstream protein of PI3K was increased in Ang II rats indicating the activity of PI3K activity was elevated. Strikingly, PI3K significantly inhibited the increase of superoxide anion level, abnormal spontaneous tone and restored endothelium-dependent relaxation in Ang II-infused hypertensive rats. These findings indicated the important role of PI3K in Ang II-infused hypertensive rats. Conclusion: ERKII2 and PI3K signaling pathways are sustained activated in Ang II-infused hypertensive rats. The activated ERKII2 and PI3K mediate the increase of vascular superoxide anion level, vascular abnormal spontaneous tone and impaired endothelium-dependent relaxation.
    • Rooibos tea flavonoids increase mineral content in human osteoblast-like cells

      Nash, Leslie Alanna; Applied Health Sciences Program (Brock University, 2014-09-02)
      Some cross-sectional and prospective studies have demonstrated a positive correlation between habitual tea consumption and bone mineral density in post-menopausal women. Rooibos tea contains no caffeine and is a rich source of flavonoids such as rutin, orientin, hyperoside and luteolin. These flavonoids have similar structures to estradiol, and therefore may act as estrogen mimics to promote favourable outcomes in bone. The overall objective of this research was to identify flavonoids that could enhance mineral content in human osteoblast Saos2 cells. Mineral was quantified by alizarin red staining and characterized by quantifying alkaline phosphatase (ALP) activity, cell mitochondria activity and toxicity, in addition to changes in regulatory markers of osteoblastic activity. Rutin (≥50μM), hyperoside (≥5.0μM), orientin (0.1μM-1.0μM, 15μM-100μM) and luteolin (5.0μM) enhanced mineral content. This was in part due to elevated ALP and mitochondrial activity, and lower toxicity, pro-inflammatory cytokines, and Wnt inhibitors.
    • Salivary and Serum Concentrations of Cortisol and Testosterone at Rest and in Response to Intense Exercise in Boys and Men

      Adebero, Tony; Applied Health Sciences Program
      This study compared salivary and serum concentrations of testosterone and cortisol at rest and in response to high-intensity exercise, in boys and men. Early morning saliva and venous blood samples were obtained pre- and 15 min post-exercise from 31 competitive swimmers (15 boys, 14.3±1.8y; 16 men, 21.6±3.1y). Exercise included an all-out 200 m swim, followed by a high-intensity interval swimming protocol (5 x 100m, 5 x 50m, and 5 x 25m). Testosterone (but not cortisol) concentration was higher in men than boys in serum and saliva (p<0.05). Cortisol concentration was higher in serum compared with saliva (p<0.01). Salivary and serum cortisol increased post-exercise, with a greater increase in men compared with boys (group-by-time interaction, p<0.001). Serum testosterone declined post-exercise in serum but not in saliva (medium-by-time interaction, p<0.01). Serum and salivary cortisol (but not testosterone) were strongly correlated in both men and boys, as evidenced by the high intraclass correlation coefficients (ICC=0.86 and 0.90, respectively; p<0.001). In summary, early morning high-intensity exercise results in a decrease in testosterone in serum, but not saliva, and an increase in cortisol irrespective of the medium used, in both boys and men. The lack of correlation in testosterone between media suggests that saliva may not be an appropriate medium to examine changes in testosterone following intense exercise. The high ICC observed between serum and saliva cortisol indicates that, in both boys and men, saliva may be used to monitor the cortisol response to exercise.
    • Sarcolemmal lipid analysis from mechanically skinned rat muscle fibres.

      Fajardo, Val Andrew; Applied Health Sciences Program (Brock University, 2011-10-24)
      Membrane lipid composition, which includes phospholipid (PL) headgroup, and fatty acid (FA) saturation, has been shown to affect cellular function. The sarcolemma (SL) membrane is integral to skeletal muscle function and health. Previous studies assessing SL lipid composition are limited as they have 1) restricted analysis to a PL level and neglected FA composition and 2) relied on aggressive membrane isolation procedures resulting in t-tubule and sarcoplasmic reticulum contamination and unknown levels of nuclear and mitochondrial contamination. Thus, to overcome these limitations, this study assessed a method of individually skinned skeletal muscle fibres as an alternative to analyze complete sarcolemmal membrane lipid composition. The major findings of this study were 1) complete SL lipid composition can be obtained 2) the SL had higher sphingomyelin content than previous studies and 3) the SL membrane had minimal nuclear and mitochondrial contamination and was void of contamination from sarcoplasmic reticulum and t-tubules.
    • Secretory immunity in overweight and obese versus normal-weight early-and late-pubertal females

      Corbett, Lauren.; Applied Health Sciences Program (Brock University, 2008-06-15)
      Obesity is a condition associated with a wide variety of health problems including hypertension, dyslipidemia, diabetes mellitus, certain forms of cancer, cardiovascular disease, and gallstones (157). TTiere is growing evidence that obesity may also be related to compromised immune function due to altered metabolic, psychological, and physical attributes (93). The aim of this study was to compare: a) immunity-related variables such as frequency of upper respiratory tract infections (URTI) and salivary secretory immunoglobulin A (sIgA) levels between overweight/obese (OB) and normal weight (NW) early-pubertal and late-pubertal girls, and b) stress-related variables such as Cortisol, melatonin, the melatonin/cortisol ratio, testosterone and the testosterone/cortisol ratio. Physical activity levels, stress indicators, and fatigue were used to explain potential differences in the dependent variables. It was hypothesized that the OB females would have lower melatonin (M) and higher Cortisol (C) and testosterone (T) levels compared with NW girls, regardless of maturity status. The altered levels of melatonin, Cortisol, and testosterone, would result in decreased M/C and T/C ratios, despite the increase in testosterone in OB females. It was hypothesized that this altered hormonal status results in a compromised immunity marked by higher frequency of upper respiratory tract infections (URTI) and decreased levels of secretory immunoglobulin A (sIgA). It was also hypothesized that OB girls would participate in less hours of physical activity than their NW counterparts and that this would relate to their stress and immunity levels. Forty (16 early- and 24 late-pubertal) overweight and obese females were compared to fifty-three (27 eariy- and 26 late-pubertal) age-matched normal-weight control subjects. Participants were categorized as early-pubertal (EP) or late-pubertal (LP) using Tanner self-staging of secondary sex characteristics. Subjects were classified into the two adiposity groups according to relative body fat (%BF), where normal weight (NW) subjects had a %BF less than 25%, and overweight and obese (OB) subjects had a %BF greater than 27.5%. Participants completed a number of questionnaires and information was collected on menstrual history, smoking history, alcohol and caffeine consumption, and medical history. Following the determination of maturity status, a complete anthropometric assessment was made including height, body mass, and body composition. All questionnaires and measurements were completed during a one-hour visit between 1 500 and 1900 hours Relative body fat was assessed using bioelectrical impedance analysis. Resting saliva samples were obtained and assayed (ELISA) for testosterone, Cortisol, melatonin and secretory immunoglobulin A. Physical activity was self-reported using the Godin- Shephard Leisure time questionnaire, and quantified using Actigraph GTIM accelerometers, which participants wore for seven consecutive days from the time they woke up in the morning, until the time they went to bed. Late-pubertal girls also completed questionnaires on their perceived stress and fatigue. Finally, all participants also filled out a one-month health log to record frequency of symptoms of upper respiratory tract infections (URTI). Significant age effects were found for testosterone, Cortisol, incidence of sickness, and sIgA when controlling for physical activity, however there were no significant effects of adiposity on any of the variables. There was a trend which neared-significance for an effect of adiposity on sIgA (p=0.01). There were no significant differences between the groups on the total selfreported leisure-time physical activity in METs per week, however EP girls recorded significantly greater levels of moderate, hard, and very hard physical activity from accelerometers. Results of the perceived stress and fatigue questionnaires in late-pubertal girls demonstrated that contrary to what was hypothesized, NW girls reported more stress and more fatigue than OB girls. Results of the present study suggest that excess adiposity in early- and latepubescent girls may not have a negative impact on immunity as hypothesized.
    • Self-Esteem and Mastery in Maintenance Cardiac Rehabilitation

      Pretty, Chelsea; Applied Health Sciences Program (Brock University, 2012-06-15)
      Background: CVD is the second leading cause of death in Canada. Mastery and self-esteem are psychosocial factors, suggested to be emerging risk factors for CVD. Purpose: The purpose of the study was two-fold; first to establish whether mastery and self-esteem predicted adherence to maintenance CR; and second, whether mastery and self-esteem improved after a 6-month maintenance CR program. Methods: Data were collected at the Brock University Heart Institute. The study involved a sample of 98 participants. At intake to the program and 6-month follow-up, participants completed a questionnaire battery which included the Rosenberg Self-Esteem Scale and the Pearlin-Schooler Mastery Scale. Results: Mastery and self-esteem scores did not alter the likelihood of adherence to the CR program. Mastery and self-esteem did significantly improve after 6-months of CR amongst participants with the lowest exercise capacity. Conclusion: Maintenance CR does improve mastery and self-esteem amongst those with diminished exercise capacity.
    • Self-Esteem and Obesity: A Longitudinal Analysis among Children and Adolescents in Niagara, Canada

      Aggarwal, Harish; Applied Health Sciences Program
      As the prevalence of obesity has surged in the past decade, with a marked increase in the rates among North American youth, it is important to comprehensively understand its downstream effects and the burden these may have on society. Besides the countless physical comorbidities of overweight and obesity in youth, several psychosocial effects have been identified including self-esteem issues. The purpose of this study is to understand the longitudinal relationship between obesity and self-esteem in Canadian children and adolescents. By quantifying this association, it may not only provide evidence for prevention, but be useful for future resource planning. The research questions are as follows: Is there a correlation between body mass and self-esteem? Is obesity status and body mass over time associated with changes in self-esteem, and if so among which sub-domains? Is the temporal relationship bi-directional where self-esteem also predicts changes in body mass? Is the relative difference in body mass between those in the same cohort also associated with self-esteem change longitudinally? Which covariate factors are significant in these suggested relationships? Data was obtained from the PHAST cohort study conducted from 2004-2010 among 2,278 children at baseline from Niagara, Canada. Participants were excluded if missing all data related to body mass and self-esteem, and multiple imputation regression was utilized to impute missing observations. Cross-sectional analysis between variables was conducted using the Pearson correlation test. Linear mixed modelling regression was conducted to examine the proposed bi-directional relationships longitudinally, accounting for fixed and random variables as well as relevant covariates and interactions. There were weak to moderate significant negative linear correlations between BMI and all self-esteem sub-domains. Baseline obesity status and BMI increases were significant predictors of decreased physical, global, athletic, and social self-esteem longitudinally. With each kg/m2 increase in BMI, physical appearance self-esteem was reduced by 0.25 units (95% CI: -0.29, -0.21, p<0.0001) over a 5-year period. Compared to those of a normal weight, those obese at baseline had an average athletic self-esteem 1.51 units lower (95% CI: -2.15, -0.87, p<0.0001). With each standard deviation increase from the mean BMI of one’s sex and age, global self-esteem was reduced by 0.53 units (95% CI: -0.62, -0.43, p<0.0001). Also, low baseline self-esteem and decreases in physical, global, and athletic self-esteem levels significantly predicted increased BMI over time. Physical activity was a significant covariate, predicting both increased self-esteem levels and decreased BMI longitudinally. The results suggest that there is a bi-directional relationship present between body mass and self-esteem in school children. Having a greater body size impairs areas of self-esteem, and having stronger self-esteem helps mitigate obesity. Physical activity is a key factor in maintaining appropriate self-esteem and body mass levels. This study can be used to guide public health officials and resource planners given the escalation of the obesity epidemic in youth.
    • Self-presentational motives in eating disorders : a known groups difference approach

      Strong, Heather.; Applied Health Sciences Program (Brock University, 2005-07-14)
      Self-presentation reflects the processes by which individuals attempt to monitor and control the impressions others form of them (Schlenker & Leary, 1982). Concerns over impressions conveyed have been linked to numerous health behaviors (Crawford & Eklund, 1994; Martin, Leary, & O'Brien, 2001). The present study investigated the role of cognitive manifestations of dispositional and situational self presentational motivation (SPM) in 131 females with known groups differences on a measure of eating disorders. Participants were classified as in-treatment (IN = 39); at risk (AT = 46); and not at risk (NOT = 46) for eating disordered behaviour. Each participant completed The Brief Fear of Negative Evaluation Scale (FNE; Leary, 1983), the Public Self-Consciousness Scale (PSC; Fenigstein, Sheier, & Buss, 1975), and the Social Physique Anxiety Scale (SPA; Hart, Leary, & Rejeski, 1989), as measures of dispositional SPM. Situational SPM was assessed through Self-Presentational Efficacy (SPE; Gammage, Hall, & Martin, 2004), and the Exercise Motivation Inventory-2 (Markland & Ingeldew, 1997). Significant differences emerged on the measure of eating disorder behaviour between AT and NOT. To determine if group differences existed on measures of trait SPM an ANOVA was conducted. Results indicated that the NOT group experienced less FNE, PSC and SPA than the IN and AT groups, and the AT group experienced less FNE and PSC than the IN group. Pearson bivariate correlations were conducted on measures of trait SPM and EMI-2 subscales theoretically linked to SPM. It was found that FNE, PSC and SPA were all positively correlated with weight management for the NOT group. To determine if group differences existed on selfpresentational exercise motives independent samples I-tests were conducted. Results revealed that the AT group was more motivated to exercise for weight management, and appearance, and social recognition than the NOT group. To determine if group differences existed on the state measure of self-presentational efficacy a series of ANOVA's were conducted. Results revealed that the NOT group experienced significantly greater self-presentational efficacy expectancy and self-presentational outcome value than the AT group. Finally, a discriminant function analysis was conducted to determine if trait SPM would predict group membership. Results revealed that 63.4% of participants were correctly classified, with SPA, PSC, and FNE differentiating the NOT group from the AT and IN groups and FNE and PSC differentiating the AT group from the IN group. Thus self-presentation motivation appears to have an influence on females who have an eating disorder and those at risk for an eating disorder. Potential applications of the influence of self-presentational motives on eating disorders and future research directions are discussed.
    • 'Sent down? Called up?': Exploring the roller coaster of loans and re-assignments in professional hockey

      McLaughlin, Bryan; Applied Health Sciences Program
      Athletes constantly face transitions in their sporting careers, which can influence the quality of their performance and well-being. The purpose of the study is to explore professional hockey players’ lived experiences with being called up and sent down in organizations. For example, an athlete can play in the National Hockey League (NHL) and is then sent down to their affiliated team in the American Hockey League (AHL) for a variety of reasons. The study utilized a phenomenological approach to understand athletes lived experiences with being called up and sent down, this allowed the researcher to move beyond brief descriptions toward understanding this specific transition athletes face. Semi-structured interviews were audio-recorded and transcribed verbatim, which occurred with six current hockey players (five current professional athletes and one competitive athlete). Data-analysis followed a two-phase process analysis to determine themes and patterns within each interview and then compared patterns across interviews to see what is common across interviews. The results were presented in three clusters such as the performance and well-being of an athlete, external influences on career, and interpretations of experiences. Further research is needed to explore the impact that loaning can have on an athlete and their well-being.
    • Sex-related differences in the microvascular function of pre-pubertal children

      Massarotto, Raffaele Joseph; Applied Health Sciences Program
      There is little research examining the effect of sex on skin blood flow (SkBF) in adults, and less in children. Sex-related differences in SkBF may help explain known thermoregulatory differences between males and females. The purpose of this study is to determine whether there are sex-related differences in the SkBF response to exercise, local heating, and acetylcholine (ACh). Additionally, the role of nitric oxide (NO) was examined. Laser-Doppler fluxmetry was used to assess forearm SkBF. Responses to exercise (30 min cycling, 60%O2max), local heating (44˚C), and ACh iontophoresis were assessed in 12 pre-pubertal boys (age=10.9 ±1.1y, O2max =1665 ± 282 ml·min-1) and 12 girls (age=11.1±1.2y, O2max =1537± 296 ml·min-1), with and without NO synthase inhibition, using Nω-nitro-L-arginine methyl ester (L-NAME) iontophoresis. Exercise-induced increase in SkBF was greater in boys compared with girls (528±290 and 374±192% of baseline, respectively, p=0.03). L-NAME blunted the SkBF response to exercise in boys and in girls (group-by-treatment interaction, p=.82). Local heating-induced SkBF was not significantly different between boys and girls (1445±900% and 1432±582%, respectively, p=.57). The ACh-induced SkBF was not different between the boys and girls, with no difference in the increase in SkBF (673±434% and 558±405%, respectively, p=.18). L-NAME blunted the SkBF response to ACh in boys and girls (group-by-treatment interaction, p=.19). These findings demonstrate that there are no differences between boys and girls in the responses to ACh and to local heating (44˚C). Additionally, the role of NO in the SkBF response appears similar in boys and girls both during exercise and ACh-mediated vasodilation. The greater SkBF response in the boys during exercise may be workload-related. Absolute and relative (%O2max) exercise intensity were not different between the two groups. Therefore, it is possible that the greater SkBF response in boys may be related to their greater workload relative to body mass (p=0.01). Additionally, sex-related factors (e.g., hormones) may interact with the exercise response or other vasodilators may be involved, resulting in the observed sex-related difference in the SkBF response to exercise.
    • Six-month outcomes of a multi-campus smoking cessation contest

      Wilson, Julie Dawn.; Applied Health Sciences Program (Brock University, 2006-05-21)
      Background: Up to 40% of North American post-secondary students smoke at least occasionally, and most want to quit. Given students' preferences for free, easy-to-access, self-directed, convenient cessation methods, a motivational, incentive-based cessation contest may be an effective way to assist students to quit. The current study describes 3- and 6-month outcomes experienced by post-secondary student smokers who entered the 'Let's Make A Deal!' contest. Methodology: Contestants from five university campuses who chose to quit completely ('Quit For Good') or reduce their tobacco consumption by 50% ('Keep The Count') were invited to participate in a study of the contest. Three and six months after registration, participants were contacted by phone to assess their smoking and quitting behaviours. Qualitative and quantitative measures were collected, including weekly tobacco consumption, efficacy to resist temptations to smoke, use of quitting aids, and strategies to cope with withdrawal. Quitting was assessed using 7-day point prevalence and continuous abstinence. Results: Seventy-four (64.9%) of the 114 participants recruited for the study completed the follow-ups. Over 31 % of participants who entered Quit For Good and 23.5% of participants who entered Keep The Count were identified as quitters at the 6-month follow-up. Among the quitters, 45.5% experienced sustained abstinence from smoking for the 6-month duration of the study. Keep The Count contestants reduced their tobacco consumption by 57.2% at 3-month follow-up and sustained some of this reduction through to the 6-month follow-up. Qualitative data provides insights into how quitters coped with withdrawal and what hampered continuing smokers' efforts to quit. Significance: A motivational, incentive-based contest for post-secondary students can facilitate both smoking cessation and harm reduction. The contest environment, incentives, resources, and "buddies" provide positive structural and social supports to help smokers overcome potential barriers to quitting, successfully stop smoking, and manage potential triggers to relapse. The contest cessation rates are higher than the typical 5-7% associated with unassisted quitting.