This thesis examines the mechanisms by which natural health products (NHP)s may affect drug disposition pathways. Adverse reactions from concomitant NHP-drug use may result from competing interactions at the level of the metabolic enzyme cytochrome P450 3A4 (CYP3A4) or the xenobiotic efflux pump P-glycoprotein (P-gp). NHPs and drugs relevant to HIV were assessed for their ability to affect these drug disposition pathways. NHP extracts were examined for their ability to inhibit CYP3A4 and stimulate P-gP ATPase. Goldenseal (GS) NHPs were the most inhibitory of CYP3A4; GS and milk thistle (MT) teas stimulated P-gp ATPase more than the positive control verapamil. GS and MT extracts, related phytochemicals, and several HIV drugs were screened for their ability to modulate CYP3A4 and P-gp ( ABCB1 gene product) expression in caco2 cell monolayers. ABCB1 expression did not change from control levels; CYP3A4 expression was more responsive, and thus a better marker for cellular response.

Objectives. To determine whether vulnerability factors (confidence with breastfeeding, postpartum depression, supplementation and perceived adequacy of support) explain breastfeeding outcome at six weeks postpartum after controlling for age and education. To describe the use of breastfeeding resources by women with vulnerability factors. Design. Cross-sectional telephone survey at six weeks postpartum. Setting. Ottawa-Carleton, Ontario, Canada. Participants. A proportionate, consecutive sample of breastfeeding women from each of four hospitals in the region was conducted (n = 526/554, 95% response rate). Methods. Secondary analyses of data, using stratified bivariate analyses to examine the relationship between each factor and breastfeeding outcome. Multivariate logistic regression analyses examined relationships between all factors and breastfeeding outcome. Missing data was 7.0%. Results. For breastfeeding mothers (n = 526), while confidence, postpartum depression and supplementation were significantly related to breastfeeding in the bivariate analyses, only confidence with breastfeeding (OR: 1.85, 95% CI: 1.50, 2.27, p < 0.001) and postpartum depression (OR: 0.28, 95% CI: 0.11, 0.71, p = 0.007) were independently related to breastfeeding in the logistic regression analyses. Approximately half of the women (n = 262, 49.8%) did not access any community resources. Conclusions. Assessment of maternal confidence with breastfeeding and postpartum depression need to be conducted. Intervention strategies to address these vulnerability factors need to be evaluated. Supplementation policies of infants in hospital need review. A cost-effectiveness analysis of the use of community resources is recommended.

Il a été démontré que l'intensité de l'exercice influence l'apport énergétique chez les hommes. L'objectif principal de cette étude portrait sur l'investigation des effets de l'intensité de l'exercice sur la prise alimentaire, la préférence macronutritionnelle, l'appétit et le profil hormonal chez des jeunes femmes. Treize jeunes femmes de poids normal et modérément actives ont participé à trois conditions expérimentales: Contrôle (C) sans exercice et deux sessions d'exercice équicaloriques (350 kilocalories), soit à faible (EFI) et haute (EHI) intensité, pratiquées à 40% et 70% de la consommation maximale d'oxygène (VO 2 peak), respectivement. À la suite de chacune de ces sessions, deux buffets (dîner et souper) ainsi que des collations (en après-midi et en soirée) ont été offerts aux participantes, qui pouvaient manger à volonté les aliments qui leurs étaient présentés. (Abstract shortened by UMI.)

Mayer's Glucostatic Theory of appetite regulation has been a precursor for many studies in this field. No studies have applied this model to extreme fluctuations of blood glucose. The present study examined if Mayer's theory holds true with carbohydrate (CHO) loading and reduction in healthy men. Six normal weight, healthy men (23.8 +/- 1.3 kg/m2) participated in a randomized crossover trial. Three day eucaloric diet conditions (75% CHO, 45% CHO, and 10% CHO) preceded a 10 h testing day in the lab where blood glucose measured every 5 min for 9 h. with appetite ratings measured every 30 min. Food was available upon request; hunger, intake and food preference were measured. No differences in daily energy intake (EI), blood glucose and appetite were noted between conditions. In all subjects during all phases, blood glucose levels decreased by 7.8+/- 11.1% prior to meal requests. Meal requests were preceded by declines in blood glucose but changes in appetite, EI and CHO preference were not seen. Key words: Glucostatic Theory, appetite, blood glucose, hunger, feeding, carbohydrates

The prevalence of childhood obesity is increasing at an alarming rate worldwide. The diets of children have shifted from nutrient-dense foods to energy-dense, nutrient-dilute foods. Using data from the Quebec Longitudinal Study of Child Development, this study aims to identify the nutritional factors related to BMI at 4 and 6 years and weight change from 4 to 6 years. This study also compares the diets of normal and overweight/obese children according to the DRI standards set by Health Canada. Associations were examined using chi-square tests, and multivariate linear and logistic regressions. The nutrition variables which appear to consistently be associated with overweight and/or BMI are linolenic acid, saturated fat and grain products. A significant difference in linolenic acid, phosphorous and iron was found between healthy weight and overweight/obese children. Also, meeting the DRI recommendations of various nutrients differs among children from various demographic and socioeconomic groups.

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