Differential predictability of four dimensions of affect intensity.

Individual differences in affect intensity are typically assessed with the Affect Intensity Measure (AIM). Previous factor analyses suggest that the AIM is comprised of four weakly correlated factors: Positive Affectivity, Negative Reactivity, Negative Intensity and Positive Intensity or Serenity. However, little data exist to show whether its four factors relate to other measures differently enough to preclude use of the total scale score. The present study replicated the four-factor solution and found that subscales derived from the four factors correlated differently with criterion variables that assess personality domains, affective dispositions, and cognitive patterns that are associated with emotional reactions. The results show that use of the total AIM score can obscure relationships between specific features of affect intensity and other variables and suggest that researchers should examine the individual AIM subscales.

The impact of the developmental timing of trauma exposure on PTSD symptoms and psychosocial functioning among older adults.

The present study examined the impact of the developmental timing of trauma exposure on posttraumatic stress disorder (PTSD) symptoms and psychosocial functioning in a large sample of community-dwelling older adults (N = 1,995). Specifically, we investigated whether the negative consequences of exposure to traumatic events were greater for traumas experienced during childhood, adolescence, young adulthood, midlife, or older adulthood. Each of these developmental periods is characterized by age-related changes in cognitive and social processes that may influence psychological adjustment following trauma exposure. Results revealed that older adults who experienced their currently most distressing traumatic event during childhood exhibited more severe symptoms of PTSD and lower subjective happiness compared with older adults who experienced their most distressing trauma after the transition to adulthood. Similar findings emerged for measures of social support and coping ability. The differential effects of childhood compared with later life traumas were not fully explained by differences in cumulative trauma exposure or by differences in the objective and subjective characteristics of the events. Our findings demonstrate the enduring nature of traumatic events encountered early in the life course and underscore the importance of examining the developmental context of trauma exposure in investigations of the long-term consequences of traumatic experiences.

The spatiotemporal dynamics of autobiographical memory: neural correlates of recall, emotional intensity, and reliving.

We sought to map the time course of autobiographical memory retrieval, including brain regions that mediate phenomenological experiences of reliving and emotional intensity. Participants recalled personal memories to auditory word cues during event-related functional magnetic resonance imaging (fMRI). Participants pressed a button when a memory was accessed, maintained and elaborated the memory, and then gave subjective ratings of emotion and reliving. A novel fMRI approach based on timing differences capitalized on the protracted reconstructive process of autobiographical memory to segregate brain areas contributing to initial access and later elaboration and maintenance of episodic memories. The initial period engaged hippocampal, retrosplenial, and medial and right prefrontal activity, whereas the later period recruited visual, precuneus, and left prefrontal activity. Emotional intensity ratings were correlated with activity in several regions, including the amygdala and the hippocampus during the initial period. Reliving ratings were correlated with activity in visual cortex and ventromedial and inferior prefrontal regions during the later period. Frontopolar cortex was the only brain region sensitive to emotional intensity across both periods. Results were confirmed by time-locked averages of the fMRI signal. The findings indicate dynamic recruitment of emotion-, memory-, and sensory-related brain regions during remembering and their dissociable contributions to phenomenological features of the memories.

Emotional intensity predicts autobiographical memory experience.

College students generated autobiographical memories from distinct emotional categories that varied in valence (positive vs. negative) and intensity (high vs. low). They then rated various perceptual, cognitive, and emotional properties for each memory. The distribution of these emotional memories favored a vector model over a circumplex model. For memories of all specific emotions, intensity accounted for significantly more variance in autobiographical memory characteristics than did valence or age of the memory. In two additional experiments, we examined multiple memories of emotions of high intensity and positive or negative valence and of positive valence and high or low intensity. Intensity was a more consistent predictor of autobiographical memory properties than was valence or the age of the memory in these experiments as well. The general effects of emotion on autobiographical memory properties are due primarily to intensity differences in emotional experience, not to benefits or detriments associated with a specific valence.

Magnetic resonance imaging of graded skeletal muscle injury in live rats.

INTRODUCTION: Increasing number of stretch-shortening contractions (SSCs) results in increased muscle injury. METHODS: Fischer Hybrid rats were acutely exposed to an increasing number of SSCs in vivo using a custom-designed dynamometer. Magnetic resonance imaging (MRI) imaging was conducted 72 hours after exposure when rats were infused with Prohance and imaged using a 7T rodent MRI system (GE Epic 12.0). Images were acquired in the transverse plane with typically 60 total slices acquired covering the entire length of the hind legs. Rats were euthanized after MRI, the lower limbs removed, and tibialis anterior muscles were prepared for histology and quantified stereology. RESULTS: Stereological analyses showed myofiber degeneration, and cellular infiltrates significantly increased following 70 and 150 SSC exposure compared to controls. MRI images revealed that the percent affected area significantly increased with exposure in all SSC groups in a graded fashion. Signal intensity also significantly increased with increasing SSC repetitions. DISCUSSION: These results suggest that contrast-enhanced MRI has the sensitivity to differentiate specific degrees of skeletal muscle strain injury, and imaging data are specifically representative of cellular histopathology quantified via stereological analyses.

Later Life Consequences of Subteratogenic Exposure to a Complex PAH Mixture in the Atlantic Killifish (Fundulus heteroclitus)

Subteratogenic and other low-level chronic exposures to toxicant mixtures are an understudied threat to environmental and human health. It is especially important to understand the effects of these exposures for contaminants, such as polycyclic aromatic hydrocarbons (PAHs) a large group of more than 100 individual compounds, which are important environmental (including aquatic) contaminants. Aquatic sediments constitute a major sink for hydrophobic pollutants, and studies show PAHs can persist in sediments over time. Furthermore, estuarine systems (namely breeding grounds) are of particular concern, as they are highly impacted by a wide variety of pollutants, and estuarine fishes are often exposed to some of the highest levels of contaminants of any vertebrate taxon. Acute embryonic exposure to PAHs results in cardiac teratogenesis in fish, and early life exposure to certain individual PAHs and PAH mixtures cause heart alterations with decreased swimming capacity in adult fish. Consequently, the heart and cardiorespiratory system are thought to be targets of PAH mixture exposure. While many studies have investigated acute, teratogenic PAH exposures, few studies have longitudinally examined the impacts of subtle, subteratogenic PAH mixture exposures, which are arguably more broadly applicable to environmental contamination scenarios. The goal of this dissertation was to highlight the later-life consequences of early-life exposure to subteratogenic concentrations of a complex, environmentally relevant PAH mixture.

A unique population of Fundulus heteroclitus (the Atlantic killifish or mummichog, hereafter referred to as killifish), has adapted to creosote-based polycyclic aromatic hydrocarbons (PAHs) found at the Atlantic Wood Industries (AW) Superfund site in the southern branch of the Elizabeth River, VA, USA. This killifish population survives in a site heavily contaminated with a mixture of PAHs from former creosote operations. They have developed resistance to the acute toxicity and teratogenic effects caused by the mixture of PAHs in sediment from the site. The primary goal of this dissertation was to compare and contrast later-life outcomes of early-life, subteratogenic PAH mixture exposure in both the Atlantic Wood killifish (AW) and a naïve reference population of killifish from King’s Creek (KC; a relatively uncontaminated tributary of the Severn River, VA). Killifish from both populations were exposed to subteratogenic concentrations of a complex PAH-sediment extract, Elizabeth River Sediment Extract (ERSE), made by collecting sediment from the AW site. Fish were reared over a 5-month period in the laboratory, during which they were examined for a variety of molecular, physiological and behavioral responses.

The central aims of my dissertation were to determine alterations to embryonic gene expression, larval swimming activity, adult behavior, heart structure, enzyme activity, and swimming/cardiorespiratory performance following subteratogenic exposure to ERSE. I hypothesized that subteratogenic exposure to ERSE would impair cardiac ontogenic processes in a way that would be detectable via gene expression in embryos, and that the misregulation of cardiac genes would help to explain activity changes, behavioral deficits, and later-life swimming deficiencies. I also hypothesized that fish heart structure would be altered. In addition, I hypothesized that the AW killifish population would be resistant to developmental exposures and perform normally in later life challenges. To investigate these hypotheses, a series of experiments were carried out in PAH-adapted killifish from Elizabeth River and in reference killifish. As an ancillary project to the primary aims of the dissertation, I examined the toxicity of weaker aryl hydrocarbon receptor (AHR) agonists in combination with fluoranthene (FL), an inhibitor of cytochrome P4501A1 (CYP1A1). This side project was conducted in both Danio rerio (zebrafish) and the KC and AW killifish.

Embryonic gene expression was measured in both killifish populations over an ERSE dose response with multiple time points (12, 24, 48, and 144 hours post exposure). Genes known to play critical roles in cardiac structure/development, cardiac function, and angiogenesis were elevated, indicating cardiac damage and activation of cardiovascular repair mechanisms. These data helped to inform later-life swimming performance and cardiac histology studies. Behavior was assessed during light and dark cycles in larvae of both populations following developmental exposure to ERSE. While KC killifish showed activity differences following exposure, AW killifish showed no significant changes even at concentrations that would cause overt cardiac toxicity in KC killifish. Juvenile behavior experiments demonstrated hyperactivity following ERSE exposure in KC killifish, but no significant behavioral changes in AW killifish. Adult swimming performance via prolonged critical swimming capacity (Ucrit) demonstrated performance costs in the AW killifish. Furthermore, swimming performance decline was observed in KC killifish following exposure to increasing dilutions of ERSE. Lastly, cardiac histology suggested that early-life exposure to ERSE could result in cardiac structural alteration and extravasation of blood into the pericardial cavity.

Responses to AHR agonists resulted in a ranking of relative potency for agonists, and determined which agonists, when combined with FL, caused cardiac teratogenesis. These experiments showed interesting species differences for zebrafish and killifish. To probe mechanisms responsible for cardiotoxicity, a CYP1A-morpholino and a AHR2-morpholino were used to mimic FL effects or attempt to rescue cardiac deformities respectively. Findings suggested that the cardiac toxicity elicited by weak agonist + FL exposure was likely driven by AHR-independent mechanisms. These studies stand in contrast to previous research from our lab showing that moderate AHR agonist + FL caused cardiac toxicity that can be partially rescued by AHR-morpholino knockdown.

My findings will form better characterization of mechanisms of PAH toxicity, and advance our understanding of how subteratogenic mixtures of PAHs exert their toxic action in naïve killifish. Furthermore, these studies will provide a framework for investigating how subteratogenic exposures to PAH mixtures can impact aquatic organismal health and performance. Most importantly, these experiments have the potential to help inform risk assessment in fish, mammals, and potentially humans. Ultimately, this research will help protect populations exposed to subtle PAH-contamination.

The Impact of Prenatal Nicotine Exposure on Impulsivity and Neural Firing in the Medial Prefrontal Cortex

Prenatal nicotine exposure (PNE) is linked to a large number of psychiatric disorders, including attention deficit hyperactivity disorder (ADHD). Current literature suggests that core deficits observed in ADHD reflect abnormal inhibitory control governed by the prefrontal cortex (PFC) of the brain. The PFC is structurally altered by PNE, but it is still unclear how neural firing is affected during tasks that test behavioral inhibition, such as the stop-signal task, or if neural correlates related to inhibitory control are affected after PNE in awake behaving animals. To address these questions, we recorded from single medial PFC (mPFC) neurons in control rats and PNE rats as they performed our stopsignal task. We found that PNE rats were faster for all trial types and were less likely to inhibit the behavioral response on STOP trials. Neurons in mPFC fired more strongly on STOP trials and were correlated with accuracy and reaction time. Although the number of neurons exhibiting significant modulation during task performance did not differ between groups, overall activity in PNE was reduced. We conclude that PNE makes rats impulsive and reduces firing in mPFC neurons that carry signals related to response inhibition.

Exercise elicits phase shifts and acute alterations of melatonin that vary with circadian phase

To examine the immediate phase-shifting effects of high-intensity exercise of a practical duration (1 h) on human circadian phase, five groups of healthy men 20-30 yr of age participated in studies involving no exercise or exposure to morning, afternoon, evening, or nocturnal exercise. Except during scheduled sleep/dark and exercise periods, subjects remained under modified constant routine conditions allowing a sleep period and including constant posture, knowledge of clock time, and exposure to dim light intensities averaging (±SD) 42 ± 19 lx. The nocturnal onset of plasma melatonin secretion was used as a marker of circadian phase. A phase response curve was used to summarize the phase-shifting effects of exercise as a function of the timing of exercise. A significant effect of time of day on circadian phase shifts was observed (P < 0.004). Over the interval from the melatonin onset before exercise to the first onset after exercise, circadian phase was significantly advanced in the evening exercise group by 30 ± 15 min (SE) compared with the phase delays observed in the no-exercise group (-25 ± 14 min, P < 0.05). Phase shifts in response to evening exercise exposure were attenuated on the second day after exercise exposure and no longer significantly different from phase shifts observed in the absence of exercise. Unanticipated transient elevations of melatonin levels were observed in response to nocturnal exercise and in some evening exercise subjects. Taken together with the results from previous studies in humans and diurnal rodents, the current results suggest that 1) a longer duration of exercise exposure and/or repeated daily exposure to exercise may be necessary for reliable phase-shifting of the human circadian system and that 2) early evening exercise of high intensity may induce phase advances relevant for nonphotic entrainment of the human circadian system.

Violence Exposure and Welfare over Time: Evidence from the Burundi Civil War

We investigate the relationship between exposure to conflict and poverty dynamics over time, using original three-waves panel data for Burundi which tracked individuals and reported local-level violence exposure from 1998 to 2012. Firstly, the data reveal that headcount poverty has not changed since 1998 while we observe multiple transitions into and out of poverty. Moreover, households exposed to the war exhibit a lower level of welfare than non-exposed households, with the difference between the two groups predicted to remain significant at least until 2017, i.e. twelve years after the conflict termination. The correlation between violence exposure and deprivation over time is confirmed in a household-level panel setting. Secondly, our empirical investigation shows how violence exposure over different time spans interacts with households' subsequent welfare. Our analysis of the determinants of households' likelihood to switch poverty status (i.e. to fall into poverty or escape poverty) combined with quantile regressions suggest that, (i) exposure during the first phase of the conflict has affected the entire distribution, and (ii) exposure during the second phase of the conflict has mostly affected the upper tail of the distribution: initially non-poor households have a higher propensity to fall into poverty while initially poor households see their propensity to pull through only slightly decrease with recent exposure to violence. Although not directly testable with the data at hand, these results are consistent with the changing nature of violence in the course of the Burundi civil war, from relatively more labour-destructive to relatively more capital-destructive.

Effects of exercise intensity on salivary antimicrobial proteins and markers of stress in active men

In the present study, we assessed the effects of exercise intensity on salivary immunoglobulin A (s-IgA) and salivary lysozyme (s-Lys) and examined how these responses were associated with salivary markers of adrenal activation. Using a randomized design, 10 healthy active men participated in three experimental cycling trials: 50% maximal oxygen uptake (VO2max), 75%VO2max, and an incremental test to exhaustion. The durations of the trials were the same as for a preliminary incremental test to exhaustion (22.3 min, sx = 0.8). Timed, unstimulated saliva samples were collected before exercise, immediately after exercise, and 1 h after exercise. In the incremental exhaustion trial, the secretion rates of both s-IgA and s-Lys were increased. An increase in s-Lys secretion rate was also observed at 75%VO2max. No significant changes in saliva flow rate were observed in any trial. Cycling at 75%VOmax and to exhaustion increased the secretion of alpha-amylase and chromogranin A immediately after exercise; higher cortisol values at 75%VO2max and in the incremental exhaustion trial compared with 50%VO2max were observed 1 h immediately after exercise only. These findings suggest that short-duration, high-intensity exercise increases the secretion rate of s-IgA and s-Lys despite no change in the saliva flow rate. These effects appear to be associated with changes in sympathetic activity and not the hypothalamic - pituitary - adrenal axis.

A systematic review of the effect of dietary exposure that could be achieved through normal dietary intake on learning and performance of school-aged children of relevance to UK schools

The aim of the present review was to perform a systematic in-depth review of the best evidence from controlled trial studies that have investigated the effects of nutrition, diet and dietary change on learning, education and performance in school-aged children (4-18 years) from the UK and other developed countries. The twenty-nine studies identified for the review examined the effects of breakfast consumption, sugar intake, fish oil and vitamin supplementation and 'good diets'. In summary, the studies included in the present review suggest there is insufficient evidence to identify any effect of nutrition, diet and dietary change on learning, education or performance of school-aged children from the developed world. However, there is emerging evidence for the effects of certain fatty acids which appear to be a function of dose and time. Further research is required in settings of relevance to the UK and must be of high quality, representative of all populations, undertaken for longer durations and use universal validated measures of educational attainment. However, challenges in terms of interpreting the results of such studies within the context of factors such as family and community context, poverty, disease and the rate of individual maturation and neurodevelopment will remain. Whilst the importance of diet in educational attainment remains under investigation, the evidence for promotion of lower-fat, -salt and -sugar diets, high in fruits, vegetables and complex carbohydrates, as well as promotion of physical activity remains unequivocal in terms of health outcomes for all schoolchildren.

The exposure to verbal abuse of student nurses gaining placement experience

Clinical placement experience has a key role to play in the socialisation and preparation of future members of the nursing profession. Aggression experienced by healthcare workers is currently receiving considerable attention and student nurses have been identified as a group vulnerable to experiencing workplace abuse (Little 1999). The primary aim of the study is to gain a greater understanding of the nature, severity, frequency and sources of verbal abuse experienced by student nurses in health care settings in the south east of England, using as a definition, “the use of inappropriate words… causing distress” (Department of Health 2003). A convenience sample of 156 third year student nurses of all four branches of one preregistration nursing programme in the south east of England was studied with questionnaires distributed retrospectively; 11 4 student nurses returned the questionnaires equating to a response rate of 73%. Results 46% of respondents reported experiencing verbal abuse, 39% had witnessed other students experiencing verbal abuse and 61% reported that they were aware of other students experiencing verbal abuse. Students reported experiencing threats to kill, racial abuse, sexually orientated verbal abuse and bullying while gaining placement experience. Student nurses are a high risk group for experiencing verbal abuse whilst gaining placement experience.In the literature, mental health and learningdisability settings are viewed as high risk areasfor experiencing aggression (Beech and Leather 2003); this study suggests that student nurses experience verbal abuse in a variety of settings and verbal abuse may be more prevalent on general medical and surgical wards than previously expected.