Prevalence of overweight and obesity in children from urban and rural Niagara

Purpose: The influence of environment in the development of overweight and obesity is an ongoing concern. This investigation examined the influence of urbanization on the rates of childhood overweight and obesity. Method: 2167 (1090M, 1077F) grade four children from 75 schools in Ontario's Niagara Region were sampled. A sophisticated algorithm overlaying electoral boundaries, population densities, and the knowledge of community members was used to classify schools into one of three location categories: urban {N= 1588), urban fringe {N= 379), and rural (A^= 234). Each subject was measured for: height, weight, and aerobic performance (Leger). Physical activity was evaluated with the self-report Participation Questionnaire (free-time and organized sport activities), and teacher's evaluations of student activity. Overweight (overweight and obesity combined) was measured both as a continuous (BMI) and categorical variable (BMI category), to evaluate the prevalence by location. A multivariate analysis was used to test for a suppression effect. Results: BMI and BMI category did not differ significantly by location or gender, and no evidence of a gender interaction existed. According to both a linear and logistic regression, physical activity or fitness levels did not suppress the influence of location on BMI and BMI category. Age, gender, free-time activity, organized sports, fitness level, and number of siblings, were all found to significantly influence overweight. Conclusions: It is plausible that the prevalence of overweight does not differ in urban and rural children from the Niagara Region. Further investigation is recommended, examining subjects by individual location of residence, in multiple regions throughout Ontario.

Grade 9 students' perceptions of the impact of a Drop Everything and Read (D.E.A.R.) program /

Educators continually look for strategies to enhance and improve the reading practices of their students. This is an especially challenging task for secondary level teachers as high school students often lack intrinsic motivation to read for pleasure (Bucher & Manning, 2004; Horton, 2005; Wooicott, Research Pty. Ltd. 2001). The purpose of this study was to detennine the effects of the Drop Everything and Read (D.E.A.R.) program on writing, on reading, and on grades, from the perspective of eight Grade 9 students. Of particular interest were the students' perceptions of the effect that participation in the program had on their grades, their writing, their motivation to reading, and their concept of themselves as readers. The eight participants were tracked over the course of a semester. Using qualitative research techniques, data were collected from four sources: two student surveys, researcher's daily field observations, students' weekly reading logs, and three open-ended one-on-one interviews. In order to gain an understanding of the impact of the D.E.A.R program, the data were corroborated, and analyzed with NVivo: N7 (2006). From the data analysis, five themes emerged as a function of the Grade 9 students' experiences in the D.E.A.R. program: Reading Preferences, Time Spent Reading, Making Associations with Reading for Pleasure, Perceptions of Self-as-Reader, and Evaluations of the D.E.A.R Program. In the interest of supporting students' positive reading habits and for the future implementation, these five themes are presented as a series of findings together with recommendations for practice.

Paragenetic history of the Ordovician Trenton Group carbonates, Southwestern Ontario

Geochemical examination of the rock matrix and cements from core material extracted from four oil wells within southwestern Ontario suggest various stages of diagenetic alteration and preservation of the Trenton Group carbonates. The geochemical compositions of Middle Ordovician (LMC) brachiopods reflect the physicochemical water conditions of the ambient depositional environment. The sediments appear to have been altered in the presence of mixed waters during burial in a relatively open diagenetic microenvironment. Conodont CAl determination suggests that the maturation levels of the Trenton Group carbonates are low and proceeded at temperatures of about 30 - 50°C within the shallow burial environment. The Trenton Group carbonates are characterized by two distinct stages of dolomitization which proceeded at elevated temperatures. Preexisting fracture patterns, and block faulting controlled the initial dolomitization of the precursor carbonate matrix. Dolomitization progressed In the presence of warm fluids (60 75°C) with physicochemical conditions characteristic of a progressively depleted basinal water. The matrix is mostly Idiotopic-S and Idiotopic-E dolomite, with Xenotopic-A dolomite dominating the matrix where fractures occur. The second stage of dolomitization involved hydrothermal basinal fluid(s) with temperatures of about 60 - 70°C. These are the postulated source for the saddle dolomite and blocky calcite cements occurring in pore space and fractures. Rock porosity was partly occluded by Idiotopic-E type dolomite. Late stage saddle dolomite, calcite, anhydrite, pyrite, marcasite and minor sphalerite and celestite cements effectively fill any remaining porosity within specific horizons. Based on cathode luminescence, precipitation of the different diagenetic phases probably proceeded in open diagenetic systems from chemically homogeneous fluids. Ultraviolet fluorescence of 11 the matrix and cements demonstrated that hydrocarbons were present during the earliest formation of saddle dolomite. Oxygen isotope values of -7.6 to -8.5 %0 (PDB), and carbon isotope values of - 0.5 and -3.0 %0 (PDB) from the latest stage dog-tooth calcite cement suggest that meteoric water was introduced into the system during their formation. This is estimated to have occurred at temperatures of about 25 - 40°C. Specific facies associations within the Trenton Group carbonates exhibit good hydrocarbon generating potential based on organic carbon preservation (1-3.5%). Thermal maturation and Lopatin burial-history evaluations suggest that hydrocarbons were generated within the Trenton Group carbonates some time after 300 Ma . Progressively depleted vanadium trends measured from hydrocarbon samples within southwestern Ontario suggests its potential use as a hydrocarbon migration indicator on local (within an oilfield) and on regional scales.

The impact of the Canadian Standardized Test of Fitness and of health counselling on health attitudes and behaviour

The purpose of this research study was to determine whether or not the use of a single day of Personal Wellness Evaluations would be meaningful enough to change the attitudes of participants toward adopting a healthier lifestyle, or if it was necessary to include regular planned health counselling alon-g with the Personal Wellness Evaluations in order to'observe changes in beliefs, attitudes and behaviours toward active living and the adoption of a healthier lifestyle. Attitudes and behaviours toward physical fitness and healthy lifestyle choices were assessed through a questionnaire composed of the following instruments: Fishbein and Ajzen Attitude and Behaviour Questionnaire, Leisure Behaviour Questionnaire, Ten Centimeter Bipolar Health Continuum, Neugarten Life Satisfaction Assessment, Job Description Index, Selected questions from the Ontario Health Survey, and the Symptom Reporting Questionnaire. Physical fitness evaluation consisted of the Canadian Standardized Test of Fitness, measures of blood pressure, and total cholesterol. The participants were divided into three groups: Group 1- CSTF & health counselling, Group 2- CSTF only, and Group 3- a control group. All three groups received the questionnaire both at the beginning and at the end of the study. Group 1 and Group 2 also participated in fitness testing at these same times, with a three-month time interval between test times. Group 1 also received weekly one-hour health education sessions during the three months between fitness testing. While there were some differences found between the three groups in this study, the results of this study suggested that this three-month workplace wellness program had no impact on the participants' attitudes and behaviours toward health and physical activity. There were no significant differences in the physical fitness measures between Group 1 and Group 2 , nor in the participants' questionnaire responses. These results may be due to the participants' lack of compliance to this wellness program. Employees who 11 participate in a workplace weIlness program must be self-motivated to comply with the program in order to receive the full benefits the program has to offer. Some participants in this study did not have the internal motivation necessary to remain in the study for the three-month period. Future research may consider implementing a workplace wellness program for a longer duration as well as incorporating a specific physical fitness program for the participants to follow. An exercise program could improve the participants' physical fitness, while the health counselling would give the individuals the health education necessary to lead a healthy lifestyle.

The metacognitive cue of fluency on taste perception

The relative ease tha t a person experiences while performing cognitive operations, namely processing fluency, affects a broad range of judgments such as product evaluations. For example, an increase in fluency through repeated exposure to product packages enhances attitude toward the brand (Janiszewski 1993). This thesis examined the effect of fluency on taste perception and demonstrated where the fluency created an advantage or disfluency created a disadvantage for taste evaluations. Experiment 1 examined the effect of perceptual fluency on taste perception. It was found that perceptual disfluency derived from r eading the labels (i.e., font) lowered taste evaluations only when it was experienced be for the sensory experience. Experiment 2 examined the effect of linguistic fluency (i.e., pronunciation) on taste perception. However there was no evidence for the effect of linguistic fluency on taste perception. Thus, it is concluded that either the effect size of linguistic fluency is lower than perceptual fluency, or participants discounted their linguistic fluency experience because they realized that the brand names used in Experiment 2 were not real brand names. To sum up, it was found that perceptual disfluency created by presenting a difficult to read product-related information created a disadvantage for taste perception compared to when no information was presented. Therefore, this thesis provides the first evidence for the effect of the metacognitive cue of fluency on sensory evaluations.

Hot cognition and activation of the medial prefrontal cortex: Self-regulating in contexts involving motivational pressures

The medial prefrontal cortex (mPFC) is involved in performance-monitoring and has been implicated in the generation of several electrocortical responses associated with self-regulation. The error-related negativity (ERN), the inhibitory Nogo N2 (N2), and the feedback-related negativity (FRN) are event-related potential (ERP) components which reflect mPFC activity associated with feedback to behavioural (ERN, N2) and environmental (FRN) consequences. Our main goal was to determine whether or not rnPFC activation varies as a function of motivational context (e.g., those involving performance-related incentives) or the use of internally versus externally generated feedback signals (i.e., errors). Additionally, we assessed medial prefrontal activity in relation to individual differences in personality and temperament. Participants completed a combination of tasks in which performance-related incentives were associated with task performance and feedback generated from internal versus external responses. MPFC activity was indexed using both ERP scalp voltage peaks and intracerebral current source density (CSD) of dorsal and ventral regions. Additionally, participants completed several questionnaires assessing personality and temperament styles. Given previous studies have shown that enhanced mPFC activity to loss (or negative) feedback, we expected that activity in the mPFC would generally be greater during the Loss condition relative to the Win condition for both the ERN and N2. Also, due to the evidence that the (vmPFC) is engaged in arousing contexts, we hypothesized that activity in the ventromedial prefrontal cortex (vmPFC) would be greater than activity in the dorsomedial prefrontal cortex (dmPFC), especially in the Loss condition of the GoNogo task (ERN). Similarly, loss feedback in the BART (FRN) was expected to engage the vmPFC more than the dmPFC. Finally, we predicted that persons rating themselves as more willing to engage in approach-related behaviours or to exhibit rigid cognitive styles would show reduced activity of the mPFC. Overall, our results emphasize the role of affective evaluations of behavioural and environmental consequences when self-regulating. Although there were no effects of context on brain activity, our data indicate that, during the time of the ERN and N2 on the MW Go-Nogo task and the FRN on the BART, the vrnPFC was more active compared to the dmPFC. Moreover, regional recruitment in the mPFC was similar across internally (ERN) and externally (FRN) generated errors signals associated with loss feedback, as reflected by relatively greater activity in the vmPFC than the dmPFC. Our data also suggest that greater activity in the mPFC is associated with better inhibitory control, as reflected by both scalp and CSD measures. Additionally, deactivation of the subgenual anterior cingulate cortex (sgACC) and lower levels of self-reported positive affect were both related to increased voluntary risk-taking on the BART. Finally, persons reporting higher levels of approach-related behaviour or cognitive rigidity showed reduced activity of the mPFC. These results are in line with previous research emphasizing that affect/motivation is central to the processes reflected by mediofrontal negativities (MFNs), that the vmPFC is involved in regulating demands on motivational/affective systems, and that the underlying mechanisms driving these functions vary across both individuals and contexts.

Exploring the impact of outgroup membership discoveries on individual outcomes and intergroup relations

Group memberships represent important components of identity, with people holding membership in various groups and categories. The groups that one belongs to are known as ingroups, and the groups that one does not belong to are known as outgroups. Movement between groups can occur, such that an individual becomes a member of a former outgroup. In some cases, this movement between groups can represent a sudden discovery for the self and/or others, especially when one becomes a member of an ambiguous, concealable, or otherwise not readily visible group. The effects of this type of movement, however, are poorly documented. The purpose of this dissertation is to investigate these outgroup membership discoveries, examining the individual intrapsychic, interpersonal, and potential intergroup effects of both self- and other-outgroup membership discoveries. Specifically, discoveries of homosexuality were examined in three studies. In Study 1, hypothetical reactions to self- and other-homosexuality discovery were assessed; in Study 2, the effects of discovering self-homosexuality (vs. self-heterosexuality) were experimentally examined; and in Study 3, the effects of discovering another’s homosexuality earlier relative to later in a developing friendship were experimentally examined. Study 1 revealed that, upon a discovery of self-homosexuality, participants expected negative emotions and a more negative change in feelings toward the self. Upon a discovery of a friend’s homosexuality, participants expected a more negative change in feelings toward the friend, but more a positive change in feelings toward homosexuals. For both hypothetical self- and friend- homosexuality discoveries, more negative expected emotions predicted more negative expected change in feelings toward the target individual (the self or friend), which in turn predicted more negative expected change in feelings toward homosexuals as a group. Further, for self-homosexuality discovery, the association between negative expected emotions and negative expected change in feelings toward the self was stronger among those higher in authoritarianism. Study 2 revealed that, upon discovering one’s own homosexuality (vs. heterosexuality), heterosexual participants experienced more negative emotions, more fear of discrimination, and more negative self-evaluations. The effect of the homosexuality discovery manipulation on negative self-evaluations was mediated by fear of discrimination. Further, those higher in authoritarianism or pre-test prejudice toward homosexuals demonstrated more negative emotions following the manipulation. Study 3 revealed that upon discovering an interaction partner’s homosexuality earlier (vs. later) participants reported a more positive contact experience, a closer bond with the partner, and more positive attitudes toward the partner. Earlier (vs. later) discovery predicted more positive contact experience, which in turn predicted a closer bond with the partner. Closer bond with the partner subsequently predicted more positive evaluations of the partner. Interestingly, the association between bond with partner and more positive attitudes toward the partner was stronger among those higher in authoritarianism or pre-test prejudice toward homosexuals. Overall, results suggest that self-homosexuality discovery results in negative outcomes, whereas discovering another’s homosexuality can result in positive outcomes, especially when homosexuality is discovered earlier (vs. later). Implications of these findings for both actual outgroup membership discoveries and social psychological research are discussed.

Humour and Learning: A Self-Study of My Practice as an Adult Educator

This study examined my lived experiences as a frontline practitioner and adult educator in a local nonprofit community organization. Using self-study research methodology, I explored my professional practice as a facilitator of job search skills training with newcomers to Canada and the impact of humour on their learning, a topic for which I have a particular passion. To better inform my practice, I designed and delivered job search skills workshops on resume writing and cold-calling/networking. I used a variety of data sources including a literature review, personal observations, and reflections as well as secondary data sources from workshop evaluations and unsolicited feedback emails from participants. Findings from the self-study indicated that adult learners who experience entertaining and fun-filled lessons that use appropriate humour have better learning results, are more confident, and are better prepared to apply skills required for achieving career goals. Further, I learned in my practice that my challenge as an adult educator is to ensure humour is appropriately used and adds value to the learning rather than being the focus of the teaching.

Exploring Teacher Candidates’ Perception of Practicum Placement Within Concurrent Teacher Education in Two Ontario Universities

In this study, teacher candidates’ perception of their concurrent education program at two Ontario universities were examined, with specific emphasis on how the programs utilized practicum placements, to determine the effectiveness in preparing teacher candidates to teach. This research also strived to uncover the best ways to optimize concurrent teacher education through practicum placements. A questionnaire and interviews were used to uncover teacher candidates’ perceptions at one teacher education program that used full integration of practicum and one that used minimal integration of practicum. The findings revealed that teacher candidates were generally more satisfied with the overall program when there was full integration of practicum. There were statistically significant differences found between the two concurrent programs with regard to practicum time and preparedness and context of the practicum and a highly significant difference found for theory-practice divide. There was also a statistically significant difference (p < .05) observed between the teacher candidates at each university in terms of their beliefs about the need for improvement of their program. Some of the improvements that participants believed could be made to their respective programs included having (a) exceptional mentor teachers and teacher educators, (b) longer placements with a balance of observation and practicum teaching, (c) clear expectations and evaluations of practicum placement, and (d) more distinct connections between theory and practice made within the programs.

Teachers’ Beliefs and Perceptions of Bullying and Bullying Prevention Initiatives

While bullying prevention programs appear to be decreasing the number of bullying incidents overseas, bullying prevention programs here in Canada have not been proving as effective. Evaluations of bullying prevention programs often focus on the outcomes and neglect to examine the training regimen for teachers. As teachers are on the front lines of bullying prevention programs, the current study explored teachers’ beliefs about the various types of bullying, their perceptions of their own abilities (e.g., teacher bullying prevention efficacy (TBPE), self-concept, and theory of mind) to implement bullying prevention initiatives, and how the school climate may influence their efficacy beliefs. Participants in the current study were 61 Canadian teachers (n = 51 women), predominantly from Ontario. Participating teachers represented all elementary division levels (primary, junior, and intermediate). Participants’ teaching experience ranged from zero years of teaching (pre-service) to 28 years of experience (M = 10.50, SD = 7.35). It was found that participants reported a relatively high TBPE score, which was related to their likely intervention in cyberbullying situations but not for other forms of bullying situations. It was found that teachers were most likely to intervene in physical bullying than verbal, relational, and cyberbullying, respectively. TBPE was influenced by the school climate. Teachers’ scores on the theory of mind scale was not a significant indicator of any teachers’ bullying beliefs. Analyses exploring the relationship between bullying beliefs and self-concept, morality predicted teachers TBPE scores and the likelihood of intervention. Teachers’ recommendations for bullying prevention training and school bullying prevention programs were explored. Results are discussed in terms of implications for practice and future research.

Evolution of Various Library Instruction Strategies: Using Student Feedback to Create and Enhance Online Active Learning Assignments

This case study traces the evolution of library assignments for biological science students from paper-based workbooks in a blended (hands-on) workshop to blended learning workshops using online assignments to online active learning modules which are stand-alone without any face-to-face instruction. As the assignments evolved to adapt to online learning supporting materials in the form of PDFs (portable document format), screen captures and screencasting were embedded into the questions as teaching moments to replace face-to-face instruction. Many aspects of the evolution of the assignment were based on student feedback from evaluations, input from senior lab demonstrators and teaching assistants, and statistical analysis of the students’ performance on the assignment. Advantages and disadvantages of paper-based and online assignments are discussed. An important factor for successful online learning may be the ability to get assistance.

Correcting the Errors : A Note on Volatility Forecast Evaluation Based on High-Frequency Data and Realized Volatilities

This note develops general model-free adjustment procedures for the calculation of unbiased volatility loss functions based on practically feasible realized volatility benchmarks. The procedures, which exploit the recent asymptotic distributional results in Barndorff-Nielsen and Shephard (2002a), are both easy to implement and highly accurate in empirically realistic situations. On properly accounting for the measurement errors in the volatility forecast evaluations reported in Andersen, Bollerslev, Diebold and Labys (2003), the adjustments result in markedly higher estimates for the true degree of return-volatility predictability.

L'attraction et la rétention des infirmières dans des programmes de personnes en perte d'autonomie liée au vieillissement: un défi pour les cadres intermédiaires

Les résultats de cette recherche faite auprès de cadres intermédiaires qui sont les gestionnaires des infirmières travaillant dans des programmes de personnes âgées en perte d'autonomie liée au vieillissement(PALV) montrent qu'il est difficile d'y attirer de nouvelles infirmières en raison du peu de popularité du domaine de la gériatrie.Afin d'y attirer des candidates, les cadres peuvent faire valoir le défi de gérer des situations de santé souvent complexes, la flexibilité des horaires de travail,l'autonomie dont elles disposent dans l'organisation de leur travail, le nombre de week-end de travail moins élevé que dans les hôpitaux et l'absence de travail supplémentaire obligatoire. Selon ces cadres, la rétention des infirmières dans de tels programmes PALV ne crée pas problème. Pour favoriser davantage cette rétention, des mesures élaborées d'orientation et d'encadrement des nouvelles infirmières de même que des mécanismes d'évaluation formelle doivent être mis en place, des efforts doivent être faits pour répartir équitablement les tâches, pour amener les infirmières à agir en tant que gestionnaires de cas et à se délester de tâches au profit des infirmières auxiliaires, et pour les sensibiliser à l'importance de la notion de prise en charge de sa santé par le client; des activités de formation continue significatives pour les infirmières doivent être élaborées à partir de l'analyse de leurs propres besoins et enfin des charges de travail particulières doivent être offertes aux infirmiàres de 55 ans et plus dans le but de les retenir au travail.

Validation des modèles de pharmacologie de sécurité et évaluation de la valeur thérapeutique de l'oxytocine dans le traitement de l'infarctus du myocarde

En février, 2009 un rapport de PHRMA (Pharmaceutical Research and Manufacturers of America) confirmait que plus de 300 médicaments pour le traitement des maladies cardiaques étaient en phase d’essais cliniques ou en révision par les agences règlementaires. Malgré cette abondance de nouvelles thérapies cardiovasculaires, le nombre de nouveaux médicaments approuvés chaque année (toutes indications confondues) est en déclin avec seulement 17 et 24 nouveaux médicaments approuvés en 2007 et 2008, respectivement. Seulement 1 médicament sur 5000 sera approuvé après 10 à 15 ans de développement au coût moyen de 800 millions $. De nombreuses initiatives ont été lancées par les agences règlementaires afin d’augmenter le taux de succès lors du développement des nouveaux médicaments mais les résultats tardent. Cette stagnation est attribuée au manque d’efficacité du nouveau médicament dans bien des cas mais les évaluations d’innocuité remportent la palme des causes d’arrêt de développement. Primum non nocere, la maxime d’Hippocrate, père de la médecine, demeure d’actualité en développement préclinique et clinique des médicaments. Environ 3% des médicaments approuvés au cours des 20 dernières années ont, par la suite, été retirés du marché suite à l’identification d’effets adverses. Les effets adverses cardiovasculaires représentent la plus fréquente cause d’arrêt de développement ou de retrait de médicament (27%) suivi par les effets sur le système nerveux. Après avoir défini le contexte des évaluations de pharmacologie de sécurité et l’utilisation des bio-marqueurs, nous avons validé des modèles d’évaluation de l’innocuité des nouveaux médicaments sur les systèmes cardiovasculaires, respiratoires et nerveux. Évoluant parmi les contraintes et les défis des programmes de développements des médicaments, nous avons évalué l’efficacité et l’innocuité de l’oxytocine (OT), un peptide endogène à des fins thérapeutiques. L’OT, une hormone historiquement associée à la reproduction, a démontré la capacité d’induire la différentiation in vitro de lignées cellulaires (P19) mais aussi de cellules souches embryonnaires en cardiomyocytes battants. Ces observations nous ont amené à considérer l’utilisation de l’OT dans le traitement de l’infarctus du myocarde. Afin d’arriver à cet objectif ultime, nous avons d’abord évalué la pharmacocinétique de l’OT dans un modèle de rat anesthésié. Ces études ont mis en évidence des caractéristiques uniques de l’OT dont une courte demi-vie et un profil pharmacocinétique non-linéaire en relation avec la dose administrée. Ensuite, nous avons évalué les effets cardiovasculaires de l’OT sur des animaux sains de différentes espèces. En recherche préclinique, l’utilisation de plusieurs espèces ainsi que de différents états (conscients et anesthésiés) est reconnue comme étant une des meilleures approches afin d’accroître la valeur prédictive des résultats obtenus chez les animaux à la réponse chez l’humain. Des modèles de rats anesthésiés et éveillés, de chiens anesthésiés et éveillés et de singes éveillés avec suivi cardiovasculaire par télémétrie ont été utilisés. L’OT s’est avéré être un agent ayant d’importants effets hémodynamiques présentant une réponse variable selon l’état (anesthésié ou éveillé), la dose, le mode d’administration (bolus ou infusion) et l’espèce utilisée. Ces études nous ont permis d’établir les doses et régimes de traitement n’ayant pas d’effets cardiovasculaires adverses et pouvant être utilisées dans le cadre des études d’efficacité subséquentes. Un modèle porcin d’infarctus du myocarde avec reperfusion a été utilisé afin d’évaluer les effets de l’OT dans le traitement de l’infarctus du myocarde. Dans le cadre d’un projet pilote, l’infusion continue d’OT initiée immédiatement au moment de la reperfusion coronarienne a induit des effets cardiovasculaires adverses chez tous les animaux traités incluant une réduction de la fraction de raccourcissement ventriculaire gauche et une aggravation de la cardiomyopathie dilatée suite à l’infarctus. Considérant ces observations, l’approche thérapeutique fût révisée afin d’éviter le traitement pendant la période d’inflammation aigüe considérée maximale autour du 3ième jour suite à l’ischémie. Lorsqu’initié 8 jours après l’ischémie myocardique, l’infusion d’OT a engendré des effets adverses chez les animaux ayant des niveaux endogènes d’OT élevés. Par ailleurs, aucun effet adverse (amélioration non-significative) ne fût observé chez les animaux ayant un faible niveau endogène d’OT. Chez les animaux du groupe placebo, une tendance à observer une meilleure récupération chez ceux ayant des niveaux endogènes initiaux élevés fût notée. Bien que la taille de la zone ischémique à risque soit comparable à celle rencontrée chez les patients atteints d’infarctus, l’utilisation d’animaux juvéniles et l’absence de maladies coronariennes sont des limitations importantes du modèle porcin utilisé. Le potentiel de l’OT pour le traitement de l’infarctus du myocarde demeure mais nos résultats suggèrent qu’une administration systémique à titre de thérapie de remplacement de l’OT devrait être considérée en fonction du niveau endogène. De plus amples évaluations de la sécurité du traitement avec l’OT dans des modèles animaux d’infarctus du myocarde seront nécessaires avant de considérer l’utilisation d’OT dans une population de patients atteint d’un infarctus du myocarde. En contre partie, les niveaux endogènes d’OT pourraient posséder une valeur pronostique et des études cliniques à cet égard pourraient être d’intérêt.

Analyse bayésienne et élicitation d’opinions d’experts en analyse de risques et particulièrement dans le cas de l’amiante chrysotile

L’appréciation de la puissance cancérogène des fibres d’amiante chrysotile repose en grande partie sur des jugements subjectifs et incertains des experts et des analystes en raison des résultats hétérogènes et équivoques d’études épidémiologiques et toxicologiques sérieuses. L’approche probabiliste bayésienne en évaluation de risques peut formaliser l’impact des jugements subjectifs et de leurs incertitudes sur les estimations de risques, mais elle est encore peu utilisée en santé publique. Le présent travail examine la possibilité d’appliquer l’approche bayésienne dans une récente élicitation d’opinions d’experts pour estimer la toxicité du chrysotile, le degré de consensus et de divergence, ainsi que les niveaux d’incertitude des experts. Les estimations des experts concordaient assez bien sur la différence de toxicité entre chrysotile et amphiboles pour les mésothéliomes. Pour le cancer du poumon, les évaluations probabilistes étaient bien plus disparates. Dans ce cas, les jugements des experts semblaient influencés à différents degrés par des biais heuristiques, surtout les heuristiques d’affect et d’ancrage liés à la controverse du sujet et à l’hétérogénéité des données. Une méthodologie rigoureuse de préparation des experts à l’exercice d’élicitation aurait pu réduire l’impact des biais et des heuristiques sur le panel.