Tests were conducted for 71 pesticides in weekly bulk (wet + dry) deposition samples collected from May 25 to September 21 over two years at two sites in the City of Winnipeg, Canada. Twenty-one pesticides and their metabolites were detected in this study and 99% of samples collected contained mixtures of two or more pesticides. Malathion and glyphosate were the largest contributors to bulk deposition in 2010 and 2011, respectively. A second study examined the mineralization of 2,4-D and 17β-estradiol using a novel in-field soil microcosm study and a series of laboratory experiments under different temperature incubations. Results indicated that temperature fluctuations do not greatly affect the amount or rate of mineralization relative to the traditionally constant laboratory incubations of 20°C; however long-term freezing of soil reduced potential mineralization over time. This research advances scientific knowledge of agri-chemical fate and provides data for strengthening current environmental policy analysis in Canada.

Resuscitation from haemorrhagic shock and the subsequent circulatory arrest remains a major clinical challenge in the care of trauma patients. Numerous experimental studies in sexually mature animals have shown a gender dimorphism in response to trauma and haemorrhagic shock. The first study was designed to evaluate sex differences in outcome after resuscitation from hypovolemic circulatory arrest. We intended to examine innate sex differences, and chose to study sexually immature animals. The study showed that cerebral cortical blood flow was greater, blood-brain-barrier was better preserved and neuronal injury was smaller in female as compared to male piglets. The second study demonstrated that female sex was associated with enhanced haemodynamic response, cardioprotection, and better survival. This cardioprotective effect was observed despite comparable estradiol and testosterone levels in male and female animals, indicating an innate gender-related cardioprotection. In both studies (I and II) female sex was associated with a smaller increase in the cerebral expression of inducible and neuronal nitric oxide synthase (iNOS and nNOS). Thus in the study III we tested the hypothesis that exogenously administered 17β-estradiol (E2) could improve neurological outcome by NOS modulation. The results showed that compared with the control group, animals in the E2 group exhibited a significantly smaller increase in nNOS and iNOS expression, a smaller blood-brain-barrier disruption and a mitigated neuronal injury. There was also a significant correlation between nNOS and iNOS levels and neuronal injury. A hypothesis if female-specific cardioprotection may be attributed to a smaller NOS activity was tested in study IV. The animals received methylene blue (MB) during CPR, but were otherwise treated according to the same protocol as studies I-II. The female-specific cardioprotection could be attributed to a smaller NOS activity, but NOS inhibition with MB did not improve survival or myocardial injury, although it abated the difference between the sexes.

ABSTRACT Evidence from knockout studies in male mice and from experiments in male rats,in which expression of the estrogen receptor alpha (ERα) gene was inhibited in the medial preoptic area (MPO), suggests that ERα is important in the control of male rat mating behavior. Therefore, in this experiment, we tested the hypothesis that activation of ERα in the MPO is sufficient to maintain mating behavior in castrated male rats receiving subcutaneously (s.c.) dihydrotestosterone (DHT), a non-aromatizable androgen. Accordingly, castrated rats treated with DHT s.c. received MPO implants of either: (i) propyl-pyrazole-triol (PPT) (Stauffer, et al 2000; Katzenellenbogen, et al 2000), a selective ERα agonist, (ii) E2 (positive controls) or (iii) cholesterol (negative controls)and sexual behavior was monitored. PPT was as effective as E2 at maintaining mating behavior suggesting that, in the MPO, ERα is sufficient to mediate responses to E2 that underlie male rat mating behavior.

Rapid increases in plasma androgens are generally associated with short-term aggressive challenges in many breeding vertebrates. However, some animals such as song sparrows (Melospiza melodia) are aggressive year-round, even during the non-breeding season, when gonads are regressed and systemic testosterone (T) levels are non-detectable. In contrast, levels of the prohormone dehydroepiandrosterone (DHEA) are elevated year-round in the plasma and brain. The local conversion of brain DHEA to potent androgens may be critical in regulating non-breeding aggression. 3β-hydroxysteroid dehydrogenase/Δ4-Δ5 isomerase (3β-HSD) catalyzes DHEA conversion to androstenedione (AE) and the cofactor NAD⁺ assists in this transformation. In this thesis, I asked whether brain 3β-HSD activity is regulated by social encounters in seasonally breeding male songbirds. In Experiment 1, I looked at the long-term seasonal regulation of brain 3β-HSD activity. 3β-HSD activity was highest in the non-breeding season compared to the breeding season and molt. In Experiment 2, I hypothesized that brain 3β-HSD activity is rapidly regulated by short-term social encounters during the non-breeding season. A 30 min social challenge increased aggressive behavior. Without exogenous NAD⁺, there was ~355% increase in 3β-HSD activity in the caudal telencephalon and ~615% increase in the medial central telencephalon compared to controls (p<0.05). With exogenous NAD⁺, there was no effect of social challenge on 3β-HSD activity. These data suggest that endogenous cofactors play a critical role in the neuroendocrine response to social challenges. The increase in brain DHEA conversion to AE during social challenges may be a mechanism to rapidly increase local androgens in the non-breeding season, when there are many costs of systemic T.

Thesis (Ph. D.)--University of Virginia, 2008. / Includes bibliographical references. Also available in electronic form as viewed 2/16/2009.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 5 uppsatser.

Diss. Linköping : Univ., 2001.

Diss. (sammanfattning) Umeå : Univ., 2004. / Härtill 5 uppsatser.

Diss. Linköping : Linköpings universitet, 2007.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Additional advisors: Asim Bej, Gene Hines, Douglas Watson, Douglas Weigent. Description based on contents viewed Oct. 2, 2008; title from PDF t.p. Includes bibliographical references.