Mechanisms of endothelin-1 induced reactive oxygen species production in vascular adventitial fibroblasts

With the relationship between endothelin-1 (ET-1) stimulation and reactive oxygen species (ROS) production unknown in adventitial fibroblasts, I examined the ROS response to ET-1 and angiotensin (Ang II). ET-1 -induced ROS peaked following 4 hrs of ET-1 stimulation and was inhibited by an ETA receptor antagonist (BQ 123, 1 uM) an extracellular signal-regulated kinase (ERK) 1/2 inhibitor (PD98059, 10 uM), and by both a specific, apocynin (10 uM), and non-specific, diphenyleneiodonium (10 uM), NAD(P)H oxidase inhibitor. NOX2 knockout fibroblasts did not produce an ET-1 induced change in ROS levels. Ang II treatment increased ROS levels in a biphasic manner, with the second peak occurring 6 hrs following stimulation. The secondary phase of Ang II induced ROS was inhibited by an ATi receptor antagonist, Losartan (100 uM) and BQ 123. In conclusion, ET-1 induces ROS production primarily through an ETA-ERKl/2 NOX2 pathway, additionally, Ang II-induced ROS production also involves an ETa pathway.

Relation of temperament and authoritative parenting on subtypes of adolescent behaviour

Over the years, researchers have investigated direct, conditional, and meditational pathways of adolescent aggression in relation to both temperament and parenting behaviours. However, no study to date has considered these relations with respect to a measure of aggression differentiated by form (e.g., overt, relational) and function (e.g., proactive, reactive). The present study examined the differential association of adolescent temperament and authoritative parenting on four subtypes of aggression. Participants included mothers, fathers, and one adolescent (between the ages of 10-19) from 663 families, recruited through random digit dialing. Parents reported on their child's temperament and occurrence of aggressive behaviours in addition to the perception of their own authoritative parenting. Adolescents reported on their own temperament and aggressive behaviours as well as on both their mother and father's authoritative parenting. Multiple regression analyses confirmed predictions that some aspects of temperament and authoritative parenting provide motivation towards the engagement of different aggressive behaviours. For example, higher negative affect was related to reactive types of aggression, whereas a strong desire for novel or risky behaviours related to proactive aggression. However, differences in effortful control altered the trajectory for both relationships. Higher levels of self-regulation reduced the impact of negative affect on reactive-overt aggression. Greater self-regulation also reduced the impact of surgency on proactive-overt aggression when age was a factor. Structural equation modeling was then used to assess the process through which adolescents become more or less susceptible to impulsive behaviours. Although the issue ofbi-directionality cannot be ruled out, temperament characteristics were the proximal correlate for aggression subtypes as opposed to authoritative parenting dimensions. Effortful control was found to partially mediate the relation between parental acceptancelinvolvement and reactive-relational and reactive-overt aggression, suggesting that higher levels of warmth and support as perceived by the child related to increased levels of self-regulation and emotional control, which in tum lead to less reactive-relational and less reactive-overt types of aggression in adolescents. On the other hand, negative affect partially mediated the relation between parental psychological autonomy granting and these two subtypes of aggression, supporting predictions that higher levels of autonomy granting (perceived independence) related to lower levels of frustration, which in tum lead to less reactive-relational and reactive-overt aggression in adolescents. Both findings provide less evidence for the evocative person-environment correlation and more support for temperament being an open system shaped by experience and authoritative parenting dimensions. As one of the first known studies examining the differential association of authoritative parenting and temperament on aggression subtypes, this study demonstrates the role parents can play in shaping and altering their children's temperament and the effects it can have on aggressive behaviour.

The form and function of aggressive subtypes: Relations with the goodness of fit between adolescent temperament and parent personality

The current research investigated whether the interaction between adolescent temperament and parent personality, consistent with the goodness of fit perspective, differentially predicted overt (e.g., kicking, punching, insulting) and relational (e.g., gossiping, rumour spreading, ostracising) forms of reactive (e.g., provoked, a response to goal blocking, unplanned and emotional) and proactive (e.g., unprovoked, goal-directed, deliberate and relatively unemotional) aggression. Mothers, fathers and their adolescent child (N = 448, age 10-17) from southern Ontario, Canada filled out questionnaires on adolescent temperament (i.e., frustration, fear, and effortful control) and aggression. Parents reported on their own personality traits (i.e., agreeableness, conscientiousness, and emotional stability). The form and function of aggression not encompassed by the subtype under investigation were controlled in each regression analysis. Consistent with the hypothesis, results indicated that a poor fit between adolescent temperament vulnerabilities and lower parent personality traits, including agreeableness, conscientiousness and emotional stability, was predictive of greater levels of differentiated aggression. For instance, lower father conscientiousness strengthened the relation between higher frustration and reactive overt aggression. Unexpectedly in some cases, temperament risk factors were more strongly associated with aggression subtypes when personality scores were at higher levels, particularly agreeableness and conscientiousness, traits normally considered to be at the optimal end of the dimension. For example, higher father agreeableness strengthened the relation between higher frustration and reactive relational aggression. At the main effects level, low fearfulness was significantly associated with only the overt subtypes of aggression, and unexpectedly, higher frustration and lower effortful control were related to both proactive and reactive subtypes of aggression. A temperamentally vulnerable adolescent was also at greater risk of displaying aggressive behaviour when the father lacked emotional stability, but not the mother. These results are broadly consistent with the prediction that temperament risk factors are more strongly associated with aggression subtypes when an adolescent predisposition does not fit well with parent personality traits. Mechanisms pertaining to stress in the family environment and the fostering of self-regulation abilities are discussed with respect to why a poor fit between temperament and parent personality is predictive of adolescent differentiated aggression.

Bullying in the Same-Sex Friendships of Young Adolescent Girls: A Qualitative Study

This qualitative, narrative study explored the bullying experiences of young adolescent girls within their same-sex dyadic and group friendships. The participants were 5 female students, ages 11 and 12 years old, from 1 private, religious school in southern Ontario. Each girl participated in an audiotaped, 30-minute, personal interview based on an unstructured interview protocol. Interview transcripts were analyzed for bullying behaviors using Marini and Dane's (2008) subtypes of bullying, including the form, function, and involvement in bullying. Interview transcripts were also analyzed for common and emerging themes using aspects of L. M., Brown and Gilligan's (1992) "Listener's Guide." The findings of this study suggested that within their same-sex friendships girls assume the roles of all participants in bullying, including bullies, victims, bystanders, and bully-victims. The findings also suggested that bullying behaviors within young adolescent girls' same-sex friendships are mainly indirect in their mode of attack and that they are both proactive and reactive. The bully behaviors identified in this study were used to inform the major themes or salient features within the dynamics of girls' same-sex friendships also identified. These themes included acceptance, intimacy, negotiation, inclusion/exclusion, moral character judgements, and power. The findings of this study will be used to inform current theory, personal and professional practice, as well as future research.

THE PREVALENCE AND PREDICTION OF PULMONARY FIBROSIS IN AN

This thesis describes an ancillary project to the Early Diagnosis of Mesothelioma and Lung Cancer in Prior Asbestos Workers study and was conducted to determine the effects of asbestos exposure, pulmonary function and cigarette smoking in the prediction of pulmonary fibrosis. 613 workers who were occupationally exposed to asbestos for an average of 25.9 (SD=14.69) years were sampled from Sarnia, Ontario. A structured questionnaire was administered during a face-to-face interview along with a low-dose computed tomography (LDCT) of the thorax. Of them, 65 workers (10.7%, 95%CI 8.12—12.24) had LDCT-detected pulmonary fibrosis. The model predicting fibrosis included the variables age, smoking (dichotomized), post FVC % splines and post- FEV1% splines. This model had a receiver operator characteristic area under the curve of 0.738. The calibration of the model was evaluated with R statistical program and the bootstrap optimism-corrected calibration slope was 0.692. Thus, our model demonstrated moderate predictive performance.

Psychopathic Traits and Endocrine Function as Predictors of Costly and Non-Costly Reactive Aggression

I investigated factors of psychopathy (fearless dominance, self-centered impulsivity) and hormones (testosterone, cortisol, estradiol) in predicting costly and non-costly reactive aggression. I hypothesized that whereas self-centred impulsivity (SCI) would promote costly aggression, fearless dominance (FD) would promote non-costly aggression. Costly aggression was measured using the Point Subtraction Aggression Paradigm and noncostly aggression was measured using one-shot dictator games. In women (n = 97; M age = 19.86 years), greater SCI and lower baseline estradiol predicted greater costly aggression; also, greater FD predicted greater non-costly aggression, particularly among women with lower SCI. In men (n = 104; M age = 20.15 years), psychopathy and endocrine function did not predict costly aggression; however, greater FD and greater increases in testosterone were associated with greater non-costly aggression. Thus, there are sex-specific links between psychopathic personality traits, hormones, and aggressive behaviour, and psychopathic traits and endocrine function predict aggressive behaviour independently of each other.