ABSTRACT | 213 29 years old, recruited from the Toronto Nutrigenomics and Health Study (TNH) cohort. FAs and CRP were measured from overnight fasting blood samples. The following FAs were measured by gas chromatography: SFA (palmitate and stearate), MUFA (palmitoleate and oleate), and PUFA (eicosapentaenoic acid, docosahexaenoic acid, and arachidonic acid). SCD-1 activity was estimated by the ratio of product to precursor (16:1/16:0 and 18:1/18:0). Associations were studied by regression analysis and adjusted for age, sex, BMI, and physical activity. Separate analyses were performed for each ethnic group. Results: Positive associations were found between serum CRP and palmitate (p<0.01), stearate (p=0.02) and the SCD-1 desaturation index (18:1/18:0, p=0.01) in Caucasians. In Asians, positive associations were also found between CRP and palmitate (p=0.01), stearate (p=0.05), and the SCD-1 desaturation index (18:1/18:0, p=0.03). No associations were found with PUFA in either population. Conclusions: Our results indicate that saturated fatty acids are signiicantly associated with CRP levels in two young adult populations. Moreover, our results suggest that an increased SCD-1 activity is also associated with an inlammatory state. 273 Increased proliferative effect of organochlorine compounds on human preadipocytes N.A. Chapados 1 , C. Casimiro 2 , M. Batal 2 , J.M. Blais 2 , F. Haman 1,2 , M.A. Robidoux 2 , and P. Imbeault 1,2 1 Behavioural and Metabolic Research Unit, Montfort Hospital, Ottawa, Ontario, Canada; 2 Faculty of Health Sciences, School of Human Kinetics and Department of Biology, University of Ottawa, Ottawa, Ontario, Canada Organochlorine compounds (OCs) are persistent chemicals that were broadly used as pesticides, polychlorinated biphenyls (PCBs), and dioxins. OCs accumulate in adipose tissue because of their lipophilicity. Of note, the circulating levels of some OCs are shown to increase with obesity. At the cellular level, the development of adipose tissue is partly related to an increased replication of preadipocytes. The effect of OCs on the proliferative capacity of preadipocytes remains, however, unknown. The aim of this study was to measure the effects of OCs exposure on the proliferative capacity of human preadipocytes. Human preadipocytes were exposed to various concentrations of highly prevalent OCs (PCBs 77, 153 and 1,1-bis (p-chlorophenyl)-2,2-dichloroethylene, DDE) for 48 hrs. At the end of the exposure period, quantiication of cell density was assessed by a cell proliferation assay. Preadipocyte proliferation signiicantly increased (~22 to 73%) in response to most of the concentrations of PCB 77, PCB 153, and DDE, as compared to the control. These indings suggest that exposure to some OCs increases the proliferative capacity of human preadipocytes, and could then be involved in the development of adipose tissue mass. 274 Energy metabolism, appetite and energy intake following an expedition in extreme environmental conditions: Results from preliminary analyses Riou ME and Doucet E University of Ottawa, Ottawa, Ontario, Canada Introduction: The aim of this study was to investigate the impact of a 30-day ski expedition through Greenland (650 km at 3000 m) on energy expenditure (EE), appetite, and energy intake (EI). Methods: Anthropometrics variables (DXA), aerobic capacity (VO2peak), resting and postprandial EE (indirect calorimetry), were measured in two it adult male subjects (age=27.50±4.95yr, BMI=24.3±1.1 kg/m² and VO2peak=59.8±5.3 ml/kg/min) before, as well as at one week, and six months after the expedition. Visual analogue scale and spontaneous EI in-lab were also assessed to measure appetite and EI, respectively. Doubly labeled water measurements are currently under analysis to determine the effects of the expedition on total EE and its components. Results: : As expected, one week after the expedition, t-test analyses revealed that fat mass (-6.3kg±2.4%, p<0.01) decreased when compared to the baseline value. No signiicant differences in resting EE were noted, while a trend for decreased postprandial EE (-45.6kcal±13.3%, p=0.056) was observed. With regards to EI, fullness decreased (-6.1±0.0%, p<0.05), while desire to eat (17.9±4.9%, p<0.05) and total EI (60.3kcal±1.5%, p<0.05), increased immediately after the expedition. However, no signiicant differences were noted six months after the expedition with the exception of desire to eat (22.1±6.3%, p<0.05) and a trend for EI (13.7kcal±7.8%, p=0.11), which remained elevated compared to baseline. Conclusion: Our results, based on these preliminary data, suggest that desire to eat and EI tend to remain elevated even six months after severe caloric deicit. 275 Virtual treks for health: A participatory method to increase physical activity and reduce weight P. Bouch, L. Milkovich, J.Lamy, and J.Saringo Red Deer Primary Care Network, Red Deer, Alberta, Canada Virtual Treks for Health were initiated in January 2009 as part of the Health Basics program consisting of a three-wave approach to promote health. Wave One involves physicians and health care providers in role-modeling health; Wave Two targets patients referred to healthy lifestyle workshops; and Wave Three facilitates community-based opportunities for active living. The goal of the treks is to increase physical activity among participants by tracking their “steps of activity” each day. Treks are based on a deined distance, time limit, required number of walking steps each day for successful completion, and are set in scenic places. People are encouraged to register as teams or individually, and log steps or activities into a web-based computer program, Steps Out. To date, four treks have been sponsored by the PCN: 1) Vancouver Island, 2) Rocky Mountains, 3) Hawaiian Islands, and 4) Jamaica. Each trek is 3–6 months in length. The Hawaiian Island Trek comprised walking 11,000 steps daily for 120 days; a total of 1000 km. Participation and completion rates, and number of steps are monitored for target groups in each trek. 935 people have participated in all treks to date and 285 (30%) completed on schedule. Participants are surveyed regarding physical activity changes linked to trek participation. Changes among those completing the Hawaiian Island trek: increase in those engaged in “3 or more times of physical activity/week,” increase in those who reported their current itness level as “very good” to “good,” and a positive inluence on overall physical activity. Learning opportunities have included: strengthening community promotion of treks, communicating with team champions, increasing participation and completion rates for each trek, dealing with computer concerns. These virtual treks have provided an interactive method to engage participants (health care practitioners, patients with lifestyle risks and the community-at-large) in increasing their physical activity as a means to healthy living and prevention of obesity. 276 Les commerces préférés des adolescents autour des écoles secondaires : mesurer la qualité de l’offre alimentaire M. Vallières 1 , C. Dufour 1 , N. Bachiri 2 , V. Drapeau 3 , A.Royer 4 , C. Després 2 , et N. Alméras 1 1 Centre de recherche de l’Institut Universitaire de cardiologie et de pneumologie de Québec, Québec, Canada; 2 École d’Architecture de l’Université Laval, Québec, Canada; 3 Département d’Éducation physique de l’Université Laval, Québec, Canada; 4 Direction régionale de santé publique de la capitale nationale, Québec, Canada