• The acute effects of systemic cytokines on peripheral nerve function in humans

      Allison, David; Applied Health Sciences Program (Brock University, 2011-10-24)
      Cytokines have been shown to cause a reduction in nerve conduction when examined using animal models. Such effects, if shown in humans, could result in detrimental effects to physical function during periods heightened systemic cytokine concentrations. The study investigated the acute effects of cytokines on nerve conduction velocity (NCV) and functional measures. Measures were taken under both basal and elevated cytokine concentrations to determine any corresponding changes to NCV. A significant positive correlation was found between the cytokine IL-6 and NCV at 2 hours post-exercise (r=0.606, p=0.048). A significant negative correlation was found between IL-1ra and NCV at 24 hours post-exercise (r=-0.652, p=0.021). A significant positive correlation was also found between IL-1ra and endurance at 1 hour post-exercise (r=0.643, p=0.033). As such, it would seem that IL-6 may potentially act to enhance nerve function while other cytokines such as IL-1ra may have negative effects and reduce NCV.
    • Acute endocrine responses to plyometrics versus resistance exercise in children

      Giannopoulou, Angeliki; Applied Health Sciences Program
      The purpose of this study was to examine the acute hormonal responses to a bout of resistance versus plyometric exercise in young male athletes. Specifically, changes in salivary cortisol, testosterone and testosterone-to-cortisol ratio from pre- to post-exercise between the two different exercise protocols were examined. Twenty-six peri-pubertal active boys participated in this cross-over study, completing two exercise sessions. During each session, participants first completed a 30 min control period, which did not include any exercise, and then was randomly assigned to perform a 45 min of either a resistance exercise or a plyometric exercise protocol. All participants crossed over to perform the other exercise protocol during their second exercise session, a week later. Four saliva samples during each protocol were taken at: baseline, pre-exercise, 5 min post-exercise and 30 min post-exercise. Significant increases in testosterone values were reported 5 min post-exercise following the resistance protocol, but not the plyometric protocol. Both exercise protocols resulted in significant cortisol decreases overtime, as well as significant testosterone-to-cortisol ratio increases. The post-exercise increases in salivary testosterone and testosterone-to-cortisol ratio followed the typical exercise induced anabolic response seen in adults. However, the post-exercise decrease in salivary cortisol was different than the typical adult response indicating an insufficient stimulus for this age group maybe due to their stage of the biological development. Thus, in the adolescent boys, exercise appears to change the anabolic to catabolic balance in favor of anabolism.
    • Adaptations of skeletal muscle pyruvate dehydrogenase kinase in response to food-restriction in mitochondrial subpopulations

      MacPherson, Laura Lynn.; Applied Health Sciences Program (Brock University, 2007-06-09)
      University, 2006 Dr. Sandra J. Peters Pyruvate dehydrogenase (PDH) catalyses the decarboxylation of pyruvate, to form acetyl-CoA. PDH activity is down-regulated by intrinsic PDH kinases (predominantly PDK2 and PDK4 isoforms), but the understanding of the PDK isoform distribution and adaptation to nutritional stresses has been restricted to mixed mitochondrial populations, and not delineated between subsarcolemmal (SS) and intermyofibrillar (IMF) subpopulations. SS and IMF mitochondria exhibit distinct morphological and biochemical properties; however the functional differences are not well understood. This study investigated the effect of fed (FED) versus 48 h total foodrestriction (FR) on rat red gastrocnemius muscle PDK2 and 4 isoform content in SS and IMF mitochondria. PDK4 content was ~3-5 fold higher in SS mitochondria compared to IMF (p=0.001), and increased with FR -3-4- fold in both subpopulations (p<0.001). PDK2 was -2.5-4 fold higher in SS mitochondria compared to IMF (p=0.001), but PDK2 was unaltered with FR. Citrate synthase activity (|imol/min/mg mitochondrial protein) was not different between either subpopulation. As well there were no significant differences between mitochondrial subpopulations in PDH complex components in both fed and FR states. These results demonstrate that there is a markedly higher content of both PDK isofonns in SS compared to IMF mitochondria. Although PDK2 does not increase in either subpopulation in response to FR, PDK4 increases to a similar extent in both SS and IMF after 48 h food-restriction.
    • Anaerobic performance in ice hockey : the effect of skate blade radius of hollow

      Winchester, Andrew.; Applied Health Sciences Program (Brock University, 2007-06-29)
      The purpose of the study was to investigate the effect of skate blade radius of hollow (ROH) on anaerobic performance, specifically during the acceleration and stopping phases of an on-ice skating test. Fifteen, male Junior B hockey players (mean age 19 y ± 1.46) were recruited to participate. On-icc testing required each participant to complete an on-ice anaerobic performance test [Reed Repeat Skate (RRS)) on three separate days. During each on-ice test, the participant's skate blades were sharpened to one of three, randomly assigned, ROH values (0.63 cm, 1.27 cm, 1.90 cm). Performance times were recorded during each RRS and used to calculate anaerobic variables [anaerobic power (W), anaerobic capacity (W), and fatigue index (s, %)). Each RRS was video recorded for the purpose of motion analysis. Video footage was imported into Peak Motus™ to measure kinematic variables of the acceleration and stopping phases. The specific variables calculated from the acceleration phase were: average velocity over 6 m (m/s), average stride length (m), and mean stride rate (strides/s). The specific variables calculated from the stopping phase were: velocity at initiation of stopping (rn/s), stopping distance (m), stopping time (s). A repeated measures ANOV A was used to assess differences in mean performance and kinematic variables across the three selected hollows. Further analysis was conducted to assess differences in trial by trial performance and kinematic variables for all hollows. The primary findings of the study suggested that skate blade ROH can have a significant effect on kinematic variables, namely stride length and stride rate during the acceleration phase and stopping distance and stopping time during the stopping phase of an on-ice anaerobic performance test. During the acceleration phase, no significant difdifferences were found in SR and SL across the three selected hollows. Mean SR on the 1.27 cm hollow was significantly slower than both the 0.63 cm and 1.90 cm hollows and SL was significantly longer when skating on the 1.27 cm hollow in comparison to the 1.90 cm hollow. During the stopping phase, stopping distance on the 0.63 cm hollow (4.12 m ± 0.14) was significantly shorter than both the 1.27 cm hollow (4.43 m ± 0.08) (p < 0.05) and the 1.90 cm ho])ow (4.35 m ± 0.12) (p < 0.05). Mean ST was also significantly shorter when stopping on the 0.63 cm hollow then both the 1.27 cm and 1.90 cm hollows. Trial by trial results clearly illustrated the affect of fatigue on kinematic variables; AV, SR, IV decreased from trial 1 to 6. There was no significant effect on anaerobic performance variables during the RRS. Altering the skate blade ROH has a significant and practical affect on accelerating and stopping performance will be discussed in this paper.
    • An analysis of students' travel motivations and images of China as a tourist destination

      Chen, Xu.; Applied Health Sciences Program (Brock University, 2004-07-14)
      Despite China's rapid growth in inbound tourism, the nature of its Canadian tourist market has been insufficiently studied. In response to this need, the objectives of this study are to identify China's destination image in Canadian students' minds, their possible internal motivations for visiting China as well as examining demographic influences on people's destination image formation. The study reviews image formation process and travel motivation categorisation, discusses their relationship, and implements Baloglu and McCleary's (1999) perceptual and affective image formation model and "push and pull factors" theory as its framework. A self-administered survey was applied to 424 undergraduate students in a Canadian university in early 2004. Exploratory factor analyses were conducted to identify perceived images and travel motivation. Summated means were calculated to illustrate the affective attitudes. A series of f-test and ANOVA tests were employed to examine the influence of demographics. An open-ended question format was adopted to analyse other images, motivations and visitation barriers that students may have. Findings demonstrate that cultural and natural attractions are the predominant image which the Canadian students have of China'; some stereotypes and negative images still influence the students' perception; travel service quality is largely unknown; increasing knowledge and seeking excitement and fun are the significant motivators in the likelihood of the Canadian students choosing to visit China; and personal interests may be a factor that significantly influences an individual's destination image and travel motivation. Raising awareness and increasing familiarity through promotion are suggested as methods to create a positive destination image of China.
    • Arterial Stiffness In Children With And Without Developmental Coordination Disorder

      Philips, Nicole; Applied Health Sciences Program (Brock University, 2014-09-04)
      The purpose of this study was to determine whether children with potential developmental coordination disorder (p-DCD) demonstrate increased arterial stiffness and thickness compared to age and school matched controls (mean age 14.7 yrs). We also assessed whether these measures differed by sex. Compliance, distensibility, and intima-media thickness (IMT) were measured at the common carotid artery for 28 children with p-DCD and 47 controls. ECG-R-wave-toe pulse wave velocity (PWV) was also measured for 29 children with p-DCD and 45 controls. We found that compared to controls males with p-DCD had significantly higher PWV (3.8±0.2 vs. 4.1±0.3, p=0.001) and lower distensibility (0.82± 0.19 vs. 0.70± 0.17, p=0.034) while females showed no significant differences (p=0.523 and p=0.123 respectively). As a result, it is apparent that sex differences exist with respect to arterial health within this population and that children with p-DCD may be more likely to develop cardiovascular disease later in life.
    • Assessment of the effects of rosemary extract on mast cell-mediated allergic inflammation

      Yousef, Michael; Applied Health Sciences Program
      The prevalence of allergic inflammatory disorders is increasing at an alarming rate, with 40-50% of school-aged children suffering today. Mast cells are immune sentinels and a driving force in both normal and pathological contexts of inflammation. Crosslinking of FcεRI by allergen-bound IgE antibodies leads to mast cell degranulation resulting in an early phase response, and the release of newly synthesized pro-inflammatory mediators, contributing to a late phase response. The mitogen-activated protein kinase (MAPK) family, phosphoinositide 3-kinase/protein kinase B (PI3K-Akt), and nuclear factor-κ-light-chain-enhancer of activated B cells (NF-κB) pathways have been established to be driving mechanisms behind mast cell-induced inflammation. Rosemary extract (RE) is rich in polyphenols and has been shown to inhibit the MAPK, PI3K-Akt, and NF-κB pathways in other cellular contexts in vitro and in in vivo. However, the effect of RE on mast cell activation has not been explored. Therefore, the aim of this study was to evaluate RE in modulating mast cell activation and FcεRI signaling via these pathways toward understanding the mechanism of action and functional outcomes. Mast cells were sensitized with anti-TNP IgE and were stimulated with the cognate allergen (TNP-BSA) under stem cell factor (SCF) potentiation and treated with 0 – 25 µg/ml RE. Samples were then collected for western blot analysis, quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), β-hexosaminidase assay, and NFкB transcription factor activity assay. Western blot analysis demonstrated that RE treatment at both 5 and 25 µg/ml inhibited phosphorylation of p38-MAPK, and treatment with 25 µg/ml inhibited JNK. qPCR analysis showed that RE treatment at 25 µg/mL resulted in decreased gene expression of IL6, TNF, IL13, CCL1, and CCL3. It also reduced Rcan1, and NFкBIA mRNA levels. ELISA analysis further supported the qPCR data showing decreases in pro-inflammatory IL-6, TNF, IL-13, CCL1, and CCL3. The β-hexosaminidase assay demonstrated that RE treatment inhibited mast cell degranulation dose-dependently to a maximum (down to 15% of control) at 25 µg/mL RE. Finally, RE reduced NFкB activity. This work suggests that RE is capable of modulating mast cell functional outcomes, and warrants further investigation for use as a potential therapeutic.
    • The association between blood pressure and vascular characteristics in children

      Phillips, Aaron; Applied Health Sciences Program (Brock University, 2010-03-09)
      Hypertension is thought to exist in up to five percent of children. A select number of studies have investigated the role elevated blood pressure plays in pediatric atherosclerotic progression. However these studies contain significant methodological flaws and fail to recognize important confounding factors. Therefore, the influence of elevated blood pressure on arterial health in children remains to be clearly understood. The purpose of this study was to investigate the association between blood pressure (BP) and arterial thickness and stiffuess in children. Common carotid artery (CCA) intima-media thickness (IMT) and distensibility (Dist), as well as systemic pulse wave velocity (PWV) were measured in 21 elevated blood pressure (EBP; BP ~ 95th percentile) and 83 normal blood pressure (NBP; BP < 90th percentile) children 11-14 years of age. Both EBP and NBP groups demonstrated BP within the normal clinical range, but EBP showed significantly elevated BP as compared to the NBP group. Independent t-tests failed to show significant differences between the EBP and NBP groups for CCA IMT (0.43 ± 0.05 mm and 0.42 ± 0.06 mm, respectively) and Dist (0.0058 ± 0.0024 mmHg-1 and 0.0064 ± 0.0019 mmHil respectively). In contrast, a significantly elevated PWV (p<O.OOl) was found in the EBP group (423 ± 35 cmls) compared to the NBP group (389 ± 24 cmls). This finding remained constant following an analysis of covariance controlling for the effects of maturation, age, sex and obesity. This study shows for the first time that children with elevated BP do not have significantly altered central arterial structure and function as measured through CCA Dist and IMT, but do possess significantly altered systemic arterial stiffuess as measured through PWV. This may be the result of sympathetic predominance and its significant influence on the peripheral vasculature. More studies are needed to clearly illustrate the temporal sequence of pediatric atherosclerotic progression in response to elevated BP.
    • The association between body composition and arterial stiffness in peri-pubescent children

      Banach, Alayna M.; Applied Health Sciences Program (Brock University, 2006-06-29)
      The objective of this study was to examine the association between body composition and arterial stiffuess in peri-pubescent boys and girls. Differences in arterial distensibility were measured in 68 children (45 normal weight, 12 overweight, and 11 obese) between the ages of9 to 12 years. Weight classification was based on age and gender-specific body mass index cut-offs, while pubertal maturation was self-reported using Tanner staging. Distensibility was determined using two-dimensional, B-Mode echo Doppler ultrasound to measure changes at the right common carotid artery (CCA) diameter changes, while carotid pulse pressure (cPP) was measured at the left CCA by applanation tonometry. One-way ANOV A analysis revealed significant differences (p<0.001) in all anthropometric measures between the normal weight and overweight children, as well as the normal weight and obese children. Body stature was only higher in obese children compared to normal weight children (p<0.01). No significant differences were found between groups regarding age or Tanner stage. Common carotid artery distensibility showed a significant difference (p<0.01) between normal weight children (0.008 ± 0.002 mmHg-1 ) compared to obese children (0.005 ± 0.002 mmHg-1 ), with a borderline significant difference between the normal and overweight subjects (p=0.06). There was no significant effect for gender between males and females across all independent variables. The strongest determinants of distensibility in children were cPP (r= -0.52, p<O.OOI), change in diastolic diameter (r= 0.50, p<O.OOI), and sum of 4 skinfold thickness (r= -0.40, p<O.OOI). Regression analysis revealed that cPP alone explained 27% of the variance in distensibility in children. In addition, cPP, diameter difference, systolic and diastolic diameter, as well as waist-to-hip ratio explained 94% of the variance among peri-pubescent children. This study greatly underscores the need for weight management for long-term prevention of cardiovascular disease in overweight and obese children.

      Zheng, Lin; Applied Health Sciences Program
      Abstract Objective: To estimate the impact of family eating behaviours on children’s academic performance as well as the role of children’s nutrition intake. Methods: A total of 2,113 students from grade six in the District School Board of Niagara (DSBN) were recruited. Academic performance was assessed through students’ Education Quality and Accountability Office (EQAO) grades, extracurricular activity, leadership and overall academic performance; and family eating behaviours (FEBs) were assessed from both general and specific aspects. Results: The less optimal general eating behaviours of child, mother and overall family were statistically significantly associated with child’s more extracurricular activity rather than child’s EQAO grades. The less optimal child’s specific eating behaviours were associated with child’s stronger leadership, more extracurricular activity and better overall academic performance; the less optimal mother’s specific eating behaviours were associated with child’s poorer EQAO grades on math and overall but stronger leadership and more extracurricular activity; and the less optimal father’s specific eating behaviours were associated with child’s less extracurricular activity and worse overall academic performance. In addition, “frequently” eating breakfast with parents was associated with child’s higher EQAO grades on math, reading, writing, and overall; “sometimes” eating lunch with parents was associated with child’s better EQAO math grade; and “frequently” eating snacks with parents was associated with child’s better EQAO reading grade but poorer writing and overall grades. Moreover, children’s intake of junk foods affected the relationship between overall family general eating behaviours and child’s extracurricular activity; children’s intake of junk foods also affected the relationship between the child’s specific eating behaviours and child’s extracurricular activity and overall academic performance; and children’s intake of macronutrients, healthy foods or junk foods affected the relationship between the mother’s specific eating behaviours and child’s EQAO math grade. Conclusions: These findings suggest that FEBs have an impact on children’s academic performance with children’s nutrition intake acting as an intermediary, thus, the importance of family meals and children’s nutrition intake should be emphasized publicly, and family-based interventions should be designed to educate family members as to promote students’ educational success.
    • The association between maternity insurance, residence status and selected perinatal outcomes among Chinese women

      Zhang, Jing (Lexie); Applied Health Sciences Program
      Objective: To investigate the impact of maternity insurance and maternal residence on birth outcomes in a Chinese population. Methods: Secondary data was analyzed from a perinatal cohort study conducted in the Beichen District of the city of Tianjin, China. A total of 2364 pregnant women participated in this study at approximately 12-week gestation upon registration for receiving prenatal care services. After accounting for missing information for relevant variables, a total of 2309 women with single birth were included in this analysis. Results: A total of 1190 (51.5%) women reported having maternity insurance, and 629 (27.2%) were rural residents. The abnormal birth outcomes were small for gestational age (SGA, n=217 (9.4%)), large for gestational age (LGA, n=248 (10.7%)), birth defect (n=48 (2.1%)) including congenital heart defect (n=32 (1.4%)). In urban areas, having maternal insurance increased the odds of SGA infants (1.32, 95%CI (0.85, 2.04), NS), but decreased the odds of LGA infants (0.92, 95%CI (0.62, 1.36), NS); also decreased the odds of birth defect (0.93, 95%CI (0.37, 2.33), NS), and congenital heart defect (0.65, 95%CI (0.21, 1.99), NS) after adjustment for covariates. In contrast to urban areas, having maternal insurance in rural areas reduced the odds of SGA infants (0.60, 95%CI (0.13, 2.73), NS); but increased the odds of LGA infants (2.16, 95%CI (0.92, 5.04), NS), birth defects (2.48, 95% CI (0.70, 8.80), NS), and congenital heart defect (2.18, 95%CI (0.48, 10.00), NS) after adjustment for the same covariates. Similar results were obtained from Bootstrap methods except that the odds ratio of LGA infants in rural areas for maternal insurance was significant (95%CI (1.13, 4.37)); urban residence was significantly related with lower odds of birth defect (95%CI (0.23, 0.89)) and congenital heart defect (95%CI (0.19, 0.91)). Conclusions: whether having maternal insurance did have an impact on perinatal outcomes, but the impact of maternal insurance on the perinatal outcomes showed differently between women with urban residence and women with rural residence status. However, it is not clear what are the reason causing the observed differences. Thus, more studies are needed.
    • The Association between Tobacco Control Policies and Marijuana Use among Ontario Undergraduate Students

      Macintosh, James; Applied Health Sciences Program (Brock University, 2013-05-15)
      Background: Research indicates a steady increase in marijuana use and that it is concurrent with tobacco. There is speculation this concurrency reaches beyond use, to where policies aimed at reducing one may result in the reduction of the other. Purpose: To investigate the association between tobacco control policies and marijuana use among young adult undergraduates. Methods: A stratified sample of Ontario universities resulted in a sample of 4,966 participants. Results: Campuses with a moderately strong policy was found to be significantly associated with decreased marijuana use compared to campuses with a weak tobacco control policy. (OR=0.52, 95% CI: 0.36-0.76). Conclusions: The findings show tobacco control strategies are related to decreased odds of marijuana use among Ontario undergraduates. These findings are important to both policy makers and researchers interested in health strategies pertaining to marijuana and tobacco use and/or how health policies aimed at reducing one risk behaviour can affect another.
    • The association between “leg length to height ratio” and blood pressure in peri-adolescents

      Wijesena, Dilani; Applied Health Sciences Program
      Background: Hypertension has a high prevalence in adults, and is a risk factor for cardiovascular diseases (CVD). Children and adolescents with higher levels of blood pressure tend to have high blood pressures as adults. Identifying children with higher levels of blood pressure would be critical for effectively implementing preventive measures among them. Stature components have been found to be associated with the risk of CVD in adults and some CVD risk factors in children. A few studies have found an association between leg length to height ratio (LLHR) and blood pressure in children; however, none of these studies have been in Canada. Objective: To ascertain the relationship between leg length to height ratio and blood pressure in Canadian youth. Methods: This cross- sectional analysis was done using data from the Heart Behavioural Environment Assessment Team (HBEAT) study, which was conducted with students from Niagara Catholic District School Board. Blood pressure and stature components of 689 students between the ages of 9-14 years were included for the analysis. The height range was 106.3 cm to 178.5 cm, and the blood pressure range was 67 mmHg to 142 mmHg for systolic blood pressure, and 30 mmHg to 96 mmHg for diastolic blood pressure. Regression models were used to examine relationships between LLHR and blood pressures. Results: In the regression analyses, for every one standard deviation increment in LLHR, the systolic, diastolic, pulse pressure, and mean arterial pressure were on average 1.08 mmHg (p<0.01), 0.88mmHg (p<0.01), 0.20mmHg and 0.95mmHg (p<0.01) lower after adjusting for selected covariates. Conclusion: Inverse relationships between LLHR and systolic, diastolic, and mean arterial pressure have been observed among Canadian youth. However, whether this can be used to predict the future risk of high blood pressure among children with a lower LLHR needs further studies.
    • The Association of Energy Intake with Body Mass in Children With and Without Probable Developmental Coordination Disorder

      Pryzbek, Michael; Applied Health Sciences Program (Brock University, 2015-01-05)
      Objective To determine if there is an association between energy intake (EI) and overweight or obesity status (OWOB) in children with and without probable developmental coordination disorder (p-DCD). Methods 1905 children were included. The Bruininks-Oseretsky Test of Motor Proficiency was used to assess p-DCD, body mass index for OWOB, and the Harvard Food Frequency Questionnaire for EI. Comparative tests and logistic regressions were performed. Results Reported EI was similar between p-DCD and non-DCD children among boys (2291 vs. 2281 kcal/day, p=0.917), but much lower in p-DCD compared to non-DCD girls (1745 vs.. 2068 kcal/day, p=0.007). EI was negatively associated with OWOB in girls only (OR: 0.82 (0.68, 0.98)). Conclusions Girls with p-DCD have a lower reported EI compared to their non-DCD peers. EI is negatively associated with OWOB in girls with p-DCD. Future research is needed to assess longitudinally the potential impact of EI on OWOB in this population.

      Schachtschneider, Carrie; Applied Health Sciences Program (Brock University, 2014-01-23)
      Variation in hiring procedures occurs within fire service human resource departments. In this study, City 1 and City 2 applicants were required to pass their biophysical assessments prior to being hired as firefighters at the beginning and end of the screening process, respectively. City 1 applicants demonstrated significantly lower resting heart rate (RHR), resting diastolic blood pressure (RDBP), body fat% (BF) and higher z-scores for BF, trunk flexibility (TF) and overall clinical assessment (p<0.05). Regression analysis found that age and conducting the biophysical assessment at the end of the screening process explained poorer biophysical assessment results in BF% (R2=21%), BF z-score (R2=22%), TF z-score (R2=10%) and overall clinical assessment z-score (R2=7%). Each of RHR (OR=1.06, CI=1.01-1.10), RDBP (OR=1.05, CI=1.00-1.11) and BF% (OR=1.20, CI=1.07-1.37) increased the odds of being a City 2 firefighter (p<0.05). Biophysical screening at the end of the hiring process may result in the hiring of a less healthy firefighter.
    • Associations Between Personal Cancer History and Lung Cancer Risk

      Everett, Karl; Applied Health Sciences Program
      The study aim was to investigate the relationship between factors related to personal cancer history and lung cancer risk as well as assess their predictive utility. Characteristics of interest included the number, anatomical site(s), and age of onset of previous cancer(s). Data from the Prostate, Lung, Colorectal and Ovarian Screening (PLCO) Cancer Screening Trial (N = 154,901) and National Lung Screening Trial (N = 53,452) were analysed. Logistic regression models were used to assess the relationships between each variable of interest and 6-year lung cancer risk. Predictive utility was assessed through changes in area-under-the-curve (AUC) after substitution into the PLCOall2014 lung cancer risk prediction model. Previous lung, uterine and oral cancers were strongly and significantly associated with elevated 6-year lung cancer risk after controlling for confounders. None of these refined measures of personal cancer history offered more predictive utility than the simple (yes/no) measure already included in the PLCOall2014 model.
    • Associations between Selected Dietary Factors, Selected Obesity-Related Metabolic Markers (Leptin, C-peptide, and High-sensitivity C-reactive Protein), and Lung Cancer: A Matched Case-Control Study Nested in the Prospective PLCO Trial

      Chen, Yixian; Applied Health Sciences Program
      The purpose of the study was to evaluate the associations between selected dietary factors, body mass index (BMI), selected obesity-related metabolic markers, and lung cancer risk as well as histological types in ever-smokers (former and current-smokers). Characteristics of interest included BMI at age 50, fruits and vegetables daily frequency, supplemental beta-carotene intake, C-peptide (CP), high-sensitivity C-reactive protein (hsCRP), and leptin concentrations. Data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial were analyzed. Linear regression models were used to describe the associations between quantitative variables. The relationships between variables of interest and lung cancer were studied by logistic regression modelling. Multivariable fractional polynomial (MFP) models were utilized to address non-linearity in these associations. Higher fruits and vegetables daily frequency and supplemental beta-carotene intake were associated with a lower risk of lung cancer in ever-smokers. Metabolic markers, C-peptide and hsCRP, were positively associated with lung cancer risk. Inverse relationships were observed between BMI and leptin with lung cancer risk. The relationships between selected dietary factors, BMI, selected metabolic markers, and lung cancer risk were more prominent in non-small cell lung cancer (NSCLC) in comparison with those in small cell lung cancer (SCLC).
    • Attention focus and balance control in young and older adults

      Paton, Erika.; Applied Health Sciences Program (Brock University, 2008-06-15)
      This thesis investigated attention focus and balance control in eighteen healthy young adults and eighteen healthy older adults. All participants performed sixteen consecutive trials of a balance task which involved standing for 30-s on an unstable platform that could rotate only in the roll direction. There were no attention focus instructions provided on any of the sixteen trials. Following the completion of the initial and final attempt in the series, participants reported "where" their attention had been focused when performing the task. The results showed differences in balance between young and older adults and improvements in balance with practice in both young and older adults. However, there were no differences in attention focus strategies between young and older adults. Both age groups directed attention to multiple sources during the balance task. An equal focus on internal (i.e., feet, trunk, and other body parts) and external (i.e., the platform) sources with little focus on events not related to the task dominated on the first attempt of the balance task. Focus on internal sources was maintained and focus on events not related to the task increased at the expense of focus on external sources on the final attempt of the balance task. Following the series of sixteen trials to establish "natural" attention focus, participants performed three randomly presented trials, each with specific attention focus instructions (i.e., think about minimizing movements of the feet, the trunk, or the platform). The results showed that, in contrast to the literature, instructions to focus on an internal source, the trunk, actually augmented control of the task as reflected in reduced trunk sway whereas instructions to focus on an internal source, the feet, or an external source, the platform, did not benefit performance on the task. Thus, the distance fi-om the interaction point of the body with the external source is critical and may not depend on whether the source is internal or external. Thus, a global attention focus instruction may not be beneficial and the nature of the task should be considered when adopting attention focus instructions for young and older adults.
    • Attenuation of skeletal muscle FFA-induced insulin resistance by the polyphenol resveratrol. Elucidation of the mechanisms involved

      Sanli, Toran.; Applied Health Sciences Program (Brock University, 2008-11-04)
      Excess plasma free fatty acids (FFA) are correlated with insulin resistance and are a risk factor for the development of type 2 diabetes. In this study we examined the effect of the polyphenol resveratrol on FF A-induced insulin resistance in skeletal muscle cells and the mechanisms involved. Incubation of L6 myotubes with the FF A palmitate significantly decreased the insulin-stimulated glucqse uptake. Importantly, the effect of palmitate was ameliorated by resveratrol. Palmitate significantly increased serine phosphorylation of IRS..; 1 and reduced insulin-stimulated Akt phosphorylation, an effect that was abolished by resveratrol. We then investigated the effect of palmitate and resveratrol on the expression and phosphorylation of JNK, mTOR, p70-S6K, and AMPK kinases. The results demonstrated that our treatments had no effect on the expression of these proteins. However, palmitate increased the phosphorylation of mTOR and p70- S6K, whereas resveratrol abolished this effect and increased the phosphorylation of AMPK. Furthermore, all effects of resveratrol were abolished with sirtuin inhibitors, sirtinol and nicotinamide. These results indicate that resveratrol ameliorated FF A-induced insulin resistance by regulating mTOR and p70-S6K phosphorylation in skeletal muscle cells, through a mechanism involving sirtuins.
    • Autonomic regulation and blood pressure in children

      Fitzgibbon, Laura K.; Applied Health Sciences Program (Brock University, 2009-01-28)
      Vagal baroreflex sensitivity (BRS) is a measure of short term blood pressure (BP) regulation through alterations in heart rate. Low BRS reflects impaired autonomic system regulation and has been found to be a surrogate marker for cardiovascular health. In particular, it has found to be associated with the pathogenesis of adult hypertension. However, only limited information exists as to the negative consequences of childhood BP on baroreflex function. The objective of this study was to investigate BRS in children with 2 different BP profiles while controlling for the effects of age, maturation, sex, and body composition. A preliminary subsample of 11-14 year-old children from the HBEAT (Heart Behavioural Environmental Assessment Team) Study was selected. The children were divided into 2 BP groups; high BP (HBP; 2:95tl1 percentile, n=21) and normal BP (NBP; <90th percentile, n=85). Following an initial 15 minutes of supine rest, 5 minutes of continuous beat-to-beat BP (Finapres) and RR interval (RRI) were recorded (standard ECG). Spectral indices were computed using Fast Fourier Transform and transfer function analysis was used to compute BRS. High frequency (HF) and low frequency (LF) power spectral areas were set to 0.15-0.4 Hz and 0.04-0.15 Hz, respectively. Body composition was measured using body mass index. After adjusting for body composition, maturation, age and sex ANCOV A results were as follows; LF and HF BRS, LF and HF RRI, and RRI total power were lower in the HBP versus NBP participants (p<0.05). As well, LF IHF SBP ratio was significantly higher in the HBP compared to the NBP group (p<0.05). The regression coefficients (unstandardized B) indicated that in changing groups (NBP to HBP) LF and HF BRS decreases by 4.04 and 6.18 ms/mmHg, respectively. Thus, as BP increases, BRS decreases. These data suggest that changes in autonomic activity occur in children who have HBP, regardless of age, sex, maturation, and body composition. Thus, despite their young age and relatively short amount of time having high BP compared with adults, these children are already demonstrating poor BP regulation and reduced cardiovagal activity. Given that childhood BP is associated with hypertension in adulthood, there is a growing concern in regards to the current cardiovascular health of our children and future adults.