Adverse Experiences, Quality of Caregiving, and Callous-Unemotional Traits Among Children with Conduct Problems

Support for developmental pathways to CU traits characterised by exposure to adversity has increased considerably in recent years. There is also evidence that quality of parenting, including parental mind-mindedness, may mitigate the impact of adversity on such traits. This thesis examined associations between adversity, parenting, and childhood CU traits. Study 1 is a systematic review with meta-analysis, which examined associations between maltreatment and childhood CU traits. Findings support distinct pathways to CU traits based on exposure to maltreatment. Maltreatment subtype was found to moderate the association, with largest effect sizes observed for neglect. Study 2 examined whether meaningful heterogeneity could be identified in early childhood, based on CU traits and adverse experiences. Using model-based cluster analysis, the best fit model identified two profiles differentiated on all variables except CU traits, suggesting adversity may be a more important marker of heterogeneity in this population. Study 3 examined parental warmth, responsiveness and mind-mindedness as moderators of the association between adversity and CU traits. Parenting variables, coded from direct observations of clinic-referred families, generally did not moderate associations between adversity and CU traits. Direct associations between fathers parenting and child CU traits were apparent. Study 4 examined domains of parenting (positive/negative parenting, parental mind-mindedness) to determine unique associations with conduct problems and CU traits. Accounting for the variance explained by positive and negative parenting, parents’ mental state attributions did not predict conduct problems and CU traits. Overall, findings support theories emphasising psychosocial risk factors in the development of CU traits. Support for parent mind-mindedness as a proximal risk factor for CU traits was limited. Parenting was generally not found to moderate associations between adversity and CU traits

Impaired driving performance as evidence of a magnocellular deficit in dyslexia and visual stress

High comorbidity and an overlap in symptomology have been demonstrated between dyslexia and visual stress. Several researchers have hypothesized an underlying or causal influence that may account for this relationship. The magnocellular theory of dyslexia proposes that a deficit in visuo-temporal processing can explain symptomology for both disorders. If the magnocellular theory holds true, individuals who experience symptomology for these disorders should show impairment on a visuo-temporal task, such as driving. Eighteen male participants formed the sample for this study. Self-report measures assessed dyslexia and visual stress symptomology as well as participant IQ. Participants completed a drive simulation in which errors in response to road signs were measured. Bivariate correlations revealed significant associations between scores on measures of dyslexia and visual stress. Results also demonstrated that self-reported symptomology predicts magnocellular impairment as measured by performance on a driving task. Results from this study suggest that a magnocellular deficit offers a likely explanation for individuals who report high symptomology across both conditions. While conclusions about the impact of these disorders on driving performance should not be derived from this research alone, this study provides a platform for the development of future research, utilizing a clinical population and on-road driving assessment techniques.11 page(s

Capturing the developmental timing of adverse childhood experiences : The Adverse Life Experiences Scale

Adverse childhood experiences (ACEs) have been associated with a range of physical and mental health problems, and it is now understood that the developmental timing of ACEs may be critically important. Despite this, there is a distinct lack of methods for the efficient assessment of such timing in research and clinical settings. We report on the development and validation of a new measure, the Adverse Life Experiences Scale (ALES), that indexes such developmental timing within a format incorporating caregivers' reports of ACEs in their own lives and those of their children. Participants were a nationally representative sample of Australian families (n = 515; Study 1), and a sample of clinic-referred families (n = 168; Study 2). Results supported the internal consistency and test-retest reliability of the ALES and indicated high levels of acceptability for the measure. In terms of validity, ALES scores were significantly associated with interview-based measures of child maltreatment and quality of the family environment, as well as measures of psychopathology across multiple informants (parents, teachers, clinician-rated). Furthermore, indices of ACEs occurring within specific age-based periods of childhood were found to explain unique variance in current symptoms of child and caregiver psychopathology, independent of the overall chronicity of those ACEs and current adversity

Spatial Habitat Structure Assembles Willow-Dependent Communities across the Primary Successional Watersheds of Mount St. Helens, USA

The eruption of Mount St. Helens in 1980 resulted in a cataclysmic restructuring of its surrounding landscapes. The Pumice Plain is one of these landscapes, where tree species such as Sitka willow (Salix sitchensis) and their dependent communities have been established along newly-formed streams. Thus, the study of these dependent communities provides a unique and rare opportunity to investigate factors influencing metacommunity assembly during true primary succession. We analyzed the influence of landscape connectivity on metacommunity assembly through a novel application of circuit theory, alongside the effects of other factors such as stream locations, willow leaf chemistry, and leaf area. We found that landscape connectivity structures community composition on willows across the Pumice Plain, where the least connected willows favored active flyers such as the western tent caterpillar (Malacosoma fragilis) or the Pacific willow leaf beetle (Pyrrhalta decora carbo). We also found that multiple levels of spatial habitat structure linked via landscape connectivity can predict the presence of organisms lacking high rates of dispersal, such as the invasive stem-boring poplar weevil (Cryptorhynchus lapathi). This is critical for management as we show that the maintenance of a heterogeneous mixture of landscape connectivity and resource locations can facilitate metacommunity dynamics to promote ecosystem function and mitigate the influences of invasive species

Mutation of Lys-120 and Lys-134 drastically reduces the catalytic rate of Cu,Zn superoxide dismutase

Lys-120 and Lys-134, located at the edge of the active site channel in most Cu,Zn superoxide dismutases, have been suggested to play a major role in steering the anionic substrate towards the catalytic copper ion. In this study, mutants of Xenopus laevis Cu,Zn superoxide dismutase have been engineered, with Lys-120 and Lys-134 changed into leucine and threonine, respectively, and their catalytic properties have been investigated by pulse radiolysis. Results obtained demonstrate that both residues decrease the catalytic rate by about 40%, in partial disagreement with previous brownian dynamics calculations, carried out on bovine Cu,Zn superoxide dismutase

Function of the Greek key connection analysed using circular permutants of superoxide dismutase.

Human Cu,Zn superoxide dismutase (SOD) is a single domain all beta-sheet protein with its eight beta-strands arranged as a Greek key beta-barrel or immunoglobulin fold. Three circularly permuted variants of SOD were made by joining the native amino- and carboxy-termini, and introducing new termini at sites originally within connections between beta-strands. The locations of the new termini were chosen to interrupt beta-turns between the two N-terminal beta-hairpins and the short cross-barrel Greek key connection. Expression levels in the Escherichia coli periplasm were indistinguishable from that of native SOD. Reaction rates for the purified proteins were similar to those of the native enzyme, indicating that the permutants are correctly folded. Interrupting the covalent cross-bracing provided by the Greek key connection reduced the stability of the protein by approximately 1.0 kcal/mol, indicating only a slight contribution to conformational stability. The experiments test and eliminate two hypotheses for folding pathways for Greek key beta-barrels that require N-terminal beta-hairpins or covalent attachment across the short Greek key connection