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Parasites are thought to have large effects on their host populations, driving genetic change, population density changes, speciation and be a major selective force maintaining sexual reproduction. Indirect signatures of parasite-mediated selection are common, but explicit examples of parasite-mediated selection in nature are lacking. In this thesis I examine parasite-mediated dynamics in a natural population of Daphnia magna that experiences an annual epidemic of the bacterial pathogen Pasteuria ramosa. I also test a novel hypothesis investigating the relationship between parasitism and the production of resting eggs. In chapter 2 a combined field study and laboratory infection experiment illustrates one of the best examples of parasite-mediated selection in a natural population, with Daphnia collected after a parasite epidemic having higher levels of parasite resistance than those collected before. This chapter also explored the relationship between parasitism and resting eggs, which are only produced during the sexual phase of reproduction. Daphnia that were reproducing sexually in the field prior to the parasite epidemic were more susceptible, supporting higher levels of parasite growth, than their asexual counterparts. This supports the idea that some genotypes invest in sex at the expense of parasite resistance. In chapter 3 I used molecular markers to investigate genotype frequency changes in the same population in relation to the parasite epidemic. The parasite epidemic was found to be associated with genetic change in the population, and a laboratory infection experiment revealed that the genotype most resistant to the parasite was also most common following the peak of the parasite epidemic. While chapter 2 explored a genetic relationship between susceptibility and resting eggs, chapter 4 explores whether crowding conditions, cues indicating parasite prevalence in the population, or direct exposure to parasite spores can induce resting egg production. I found that crowding conditions or parasite prevalence enhance levels of male and resting egg production, but patterns were entirely dependent on Daphnia genotypes. There was no indication that exposure to parasite spores affects levels of sexual reproduction.

The nutritional care and management of patients includes provision of adequate nutrition support to ensure that they attain and maintain a desirable body weight, improve nutritional status and avoid negative outcomes associated with over- or underfeeding. The success of nutrition support relies on accurately estimating energy requirements so that adequate energy and nutrients can be provided to the patient. Energy requirements are most accurately determined by measurement of energy expenditure. Most methods for doing so however are expensive, time-consuming, require trained technicians to perform them and are therefore impractical in the clinical setting. As such, prediction equations, which are easy to use, inexpensive and universally available, are commonly used to estimate the energy requirements of hospitalised patients. The accuracy of these equations however is questionable. Recently, a new portable hand-held indirect calorimeter (MedGem(tm), HealtheTech, USA), which has been promoted for its ease of use and relatively short measurement time, has been validated in healthy subjects but is yet to be validated in patients with illnesses. Weight loss and malnutrition occur commonly in patients with cancer and are often thought to be associated with disturbances in energy metabolism caused by the tumour. Minimising weight loss is an important goal for the nutritional care of patients with cancer. The ability to accurately determine the energy requirements of these patients is therefore essential for the provision of optimal nutrition support. This research project proceeded in two phases. Phase 1 aimed to determine current methods used by dietitians for estimating adult patients' energy requirements using a descriptive study. Results of this study informed phase 2, which aimed to investigate differences in energy expenditure of cancer patients compared to healthy control subjects and to compare different methods for determining energy requirements of people with cancer in the clinical setting. To address phase 1 a national cross-sectional survey of dietitians working in acute care adult hospitals was undertaken to determine their usual dietetic practice with respect to estimating patients' energy requirements. Responses to the survey (n=307, 66.2%) indicated a large variation in dietitians' practice for estimating energy requirements particularly with respect to the application of methods involving injury factors. When applied to a case study, these inconsistencies resulted in an extremely wide range for the calculated energy requirement, suggesting that there is error inherent in the use of prediction methods, which may be associated with negative consequences associated with under- or overfeeding. The types of patients for whom dietitians estimate energy requirements appears to be heavily influenced by feeding method. Initial dietetic education was identified as the main influencing factor in the choice of method for estimation of energy requirements. Phase 2 was addressed using four studies based on the same study population - a case-control study, two clinical validation studies and a measurement methods study. Patients had histologically proven solid tumours, excluding tumours of the breast, prostate and brain, and were undergoing anti-cancer therapy (n=18). Healthy control subjects were group matched to cancer patients by gender, age, height and weight from a purposive sample (n=17). Resting energy expenditure (REE) was measured by respiratory gas exchange using a traditional indirect calorimeter (VMax 229) and the MedGem indirect calorimeter. A measurement methods side-study established that steady state defined as a three-minute period compared to a five-minute period measured REE within clinically acceptable limits. REE was also predicted from a range of prediction equations. Analyses of available data found that REE in cancer patients was not significantly different from healthy subjects, with only a 10% higher REE observed in this sample of cancer patients when adjusted for fat free mass. For both cancer patients and healthy subjects the portable MedGem indirect calorimeter and all prediction equations did not measure or estimate individual REE within clinically acceptable limits compared to the VMax 229 (limits of agreement of approximately -40% to 30% for both the MedGem and prediction equations). Collectively, the results of this research project have indicated that current practical methods for determining patients' energy requirements in a clinical setting do not accurately predict the resting energy expenditure of individual subjects, healthy or with cancer. Greater emphasis should therefore be placed on ensuring intake meets requirements. For this to occur, dietetic practice should be focused on directly monitoring both patients' actual energy intake and patient outcomes, such as weight, body composition and nutritional status, to determine whether energy requirements are being met. This research has led to multiple recommendations for dietetic practice, focusing on the standardisation of education practices. Recommendations for future research address methodological improvements.

Researchers have examined psychosocial risk variables (e.g., hostility) related to high resting blood pressure (BP), with the majority of findings suggesting that hostility is associated with increased resting BP. Additionally, it has been proposed that constructive verbal anger expression is a protective factor for hypertension (Davidson, MacGregor, Stuhr, Dixon, & MacLean, 2000; Davidson, MacGregor, Stuhr, & Gidron, 1999), while others have hypothesized that humor promotes physical health (i.e., the humor-health hypothesis) (Martin, Puhlik-Doris, Larsen, Gray, & Weir, 2003; McClelland & Cheriff, 1997). The primary purpose of the present study is to examine the relations between hostility, humor styles, constructive verbal anger, and resting BP, with an emphasis on the humor-health hypothesis. One hundred and ninety nine undergraduate university participants had six resting blood pressure measurements taken at three-minute intervals. Participants then completed the following questionnaires online in a randomized order: Cook-Medley Hostility Scale (CMH), Constructive Anger Behaviour-Verbal Scale (CAV), Humor Styles Questionnaire (HSQ), and a health and demographic questionnaire. A series of hierarchical regressions were conducted to test the hypotheses with resting systolic BP (SBP) and resting diastolic BP (DBP). Two health and demographic variables, age and body mass index (BMI), were entered into step 1 of all the regressions analyzed as covariates. In step 2 of each regression model, the respective psychosocial variables were independently entered. Comparisons were conducted between the various psychosocial variables entered into step 2 to determine which variable accounts for the most unique variance in resting SBP and DBP. Small to moderate positive correlations were observed between age and resting BP, as well as BMI and resting BP. Regarding psychosocial variables, small positive correlations were observed between affiliative humor and resting SBP, and between self-enhancing humor and resting BP. Multiple regression analyses revealed that after controlling for age and BMI, adaptive humor styles uniquely predicted higher resting SBP, while no psychosocial variables predicted resting DBP. The present investigation provides evidence suggesting that psychosocial risk factors are not associated with resting BP while also contradicting the humor-health hypothesis, suggesting that adaptive humor is associated with increased resting BP.

Our senses, while limited, shape our perception of the world and contribute to the functional architecture of the brain. This dissertation investigates the role of sensory modality and task demands in the cortical organization of healthy human adults using functional magnetic resonance imaging (fMRI). This research provides evidence for sensory modality bias in frontal cortical regions by directly contrasting auditory and visual sustained attention. This contrast revealed two distinct visual-biased regions in lateral frontal cortex - superior and inferior precentral sulcus (sPCS, iPCS) - anatomically interleaved with two auditory-biased regions - transverse gyrus intersecting precentral sulcus (tgPCS) and caudal inferior frontal sulcus (cIFS). Intrinsic (resting-state) functional connectivity analysis demonstrated that sPCS and iPCS fall within a broad visual-attention network, while tgPCS and cIFS fall within a broad auditory-attention network. Unisensory (auditory or visual) short-term memory (STM) tasks assessed the flexible recruitment of these sensory-biased cortical regions by varying information domain demands (e.g., spatial, temporal). While both modalities provide spatial and temporal information, vision has greater spatial resolution than audition, and audition has excellent temporal precision relative to vision. A visual temporal, but not a spatial, STM task flexibly recruited frontal auditory-biased regions; conversely, an auditory spatial task more strongly recruited frontal visual-biased regions compared to an auditory temporal task. This flexible recruitment extended to an auditory-biased superior temporal lobe region and to a subset of visual-biased parietal regions. A demanding auditory spatial STM task recruited anterior/superior visuotopic maps (IPS2-4, SPL1) along the intraparietal sulcus, but neither spatial nor temporal auditory tasks recruited posterior/interior maps. Finally, a comparison of visual spatial attention and STM under varied cognitive load demands attempted to further elucidate the organization of posterior parietal cortex. Parietal visuotopic maps were recruited for both visual spatial attention and working memory but demonstrated a graded response to task demands. Posterior/inferior maps (IPS0-1) demonstrated a linear relationship with the number of items attended to or remembered in the visual spatial tasks. Anterior/superior maps (IPS2-4, SPL1) demonstrated a general recruitment in visual spatial cognitive tasks, with a stronger response for visual spatial attention compared to STM.

No description available.

Early life stress (ELS) affects the developing brain and impacts capacity for self-regulation and risk for psychopathology. The high spatial resolution of functional magnetic resonance imaging (fMRI) confers an advantage for studying specific neural regions posited to link ELS with subsequent functioning. The first chapter in this dissertation reviews the literature establishing the feasibility and utility of fMRI research with infants and young children. This chapter examines methodological issues and outlines the potential for this technique to make unique contributions to understanding how ELS influences brain development. The next two chapters present results from a study that employed a functional activation paradigm and resting state functional connectivity MRI (rs-fcMRI) to examine associations between a common source of ELS, non-physical interparental conflict, and neural functioning during infancy. The functional activation paradigm focused on emotional tone of voice as a stimulus relevant to interparental conflict, which is likely salient to infants. Higher levels of interparental conflict (as reported by mothers) were associated with infants (6 to 12 months of age) showing greater reactivity to very angry versus neutral tone of voice in neural regions associated with processing and regulation of stress and emotion (hypothalamus and rostral anterior cingulate cortex). The rs-fcMRI analysis examined coordinated neural functioning in the absence of stimuli, focusing on the amygdala as a key region for understanding the impact of ELS and the posterior cingulate cortex as part of a group of regions that show higher levels of activity in the absence of stimuli (the default network). The results replicate previous work characterizing the default network in infants and provide novel evidence for the functional connectivity of the amydgala and amygdala subregions during infancy. Interparental conflict was associated with variation in the connectivity of both regions. Thus levels of interparental conflict were associated with neural reactivity to a stressor-relevant stimulus and with patterns of coordinated neural functioning in the absence of such stimuli. These results provide support for the utility of using fMRI with infants to examine early emerging associations between common forms of ELS and brain functioning. This dissertation includes previously published and co-authored material. / 2016-10-17

O presente trabalho avaliou a mortalidade de suínos no pré-abate através de análises anatomopatológica a fim de identificar as causas envolvidas. O estudo foi realizado durante os períodos de verão e inverno do ano de 2015 em um frigorífico do estado do Rio Grande do Sul que conta com Serviço de Inspeção Federal e está localizado na região do Vale do Taquari. No verão, foram contabilizadas 141 mortes do total de 117.260 (0,12%), enquanto que, no inverno, foram 75 mortes do total de 127.286 (0,05%). Dos 216 suínos mortos nos dois períodos, 170 foram submetidos a necropsia. Amostras foram examinadas no laboratório do Setor de Patologia Veterinária da Faculdade de Veterinária da Universidade Federal do Rio Grande do Sul. Entre as causas de morte diagnosticadas, as úlceras gástricas na região do quadrilátero esofágico e piloro foram as mais frequentes, sendo 29,2% (31/106) no verão e 32,8% (21/64) no inverno. As alterações pulmonares, como pneumonia enzoótica, influenza, broncopneumonia bacteriana e pleurite, foram o segundo diagnóstico mais frequente, sendo observado 15,1% (16/106) no verão e 18,8% (12/64) no inverno. A insuficiência cardíaca, incluindo pericardite bacteriana, endocardite bacteriana, cardiomiopatia hipertrófica, miocardite, infarto do miocárdio e neoplasia, apresentou-se em uma frequência de 14,2% (15/106) no verão e 9,4% (6/64) no inverno. A dilatação gástrica aguda causada pelo excesso de ração no estômago também foi um importante diagnóstico obtido, sendo 8,5% (9/106) no verão e 4,7% (3/64) no inverno. Rupturas de fígado foram observadas em 5,7% das mortes (6/106) no verão e 7,8% (5/64) no inverno, enquanto que rupturas de baço foram observadas em 0,9% das mortes (1/106) no verão e 1,6% (1/64) no inverno, representando diagnósticos importantes, mas pouco descritos na literatura como causa de morte. A enteropatia proliferativa foi diagnosticada em 5,7% dos casos (6/106) no verão e 4,7% (3/64) no inverno. A torção de mesentério foi responsável por 3,8% (4/106) das mortes ocorridas no verão e 6,2% (4/64) no inverno. Em menor frequência observaram-se as polisserosites, presente em 2,8% (3/106) dos suínos mortos no verão e 3,1% (2/64) no inverno. Já a fratura de fêmur somente foi observada em 0,9% dos casos (1/106) no período de verão. Casos inconclusivos representaram 13,2% (14/106) no verão e 10,9% (7/64) no inverno. Também se observou que a mortalidade pré-abate nas duas épocas do ano avaliadas ocorre mais em suínos que estão no período de descanso (64,5% (139/216) do que durante o transporte (35,5% (77/216). / The present study evaluated the mortality of pigs just prior to slaughter through histopathological analysis in order to identify the causes of death. The study was conducted during the summer and winter of 2015 in a slaughter that has Federal Inspection Service in Rio Grande do Sul State located in Taquari Valley. During the summer, 141 deaths were accounted from the total deaths of 117 260 (0.12%), while, in the winter, it were 75 deaths from the total of 127.286 (0.05%). Of the 216 carcasses of dead animals in both periods, 170 were analyzed. Samples were examined in the laboratory of the Veterinary Pathology Sector of the Veterinary School of the Federal University of Rio Grande do Sul. Among the causes of death diagnosed, gastric ulcers in the esophageal quadrilateral region and pylorus were the most frequent, which represented 29.2% (31/106) in the summer and 32.8% (21/64) in winter. Pulmonary disorders such as enzootic pneumonia, influenza, bacterial pneumonia and pleuritis, were the second most frequent diagnosis, observed in 15.1% (16/106) in the summer and 18.8% (12/64) in the winter. Heart failure, including bacterial pericarditis, bacterial endocarditis, hypertrophic cardiomyopathy, myocarditis, myocardial infarction and neoplasia, had a frequency of 14.2% (15/106) in the summer and 9.4% (6/64) in the winter. Acute gastric dilatation caused by excess food in the stomach was also an important diagnosis, with 8.5% (9/106) in the summer and 4.7% (3/64) in the winter. Liver ruptures were observed in 5.7% of deaths (6/106) in summer and 7.8% (5/64) in the winter, while spleen ruptures were observed in 0.9% of deaths (1/106 ) in summer and 1.6% (1/64) in the winter, representing important diagnoses, however it is rarely reported in the literature as a cause of pig death. Proliferative enteropathy was diagnosed in 5.7% of the cases (6/106) in the summer and 4.7% (3/64) in the winter. Mesenteric torsion was diagnosed in 3.8% (4/106) of deaths in the summer and 6.2% (4/64) in the winter. Polyserositis were observed in lower frequency, 2.8% (3/106) of dead pigs in the summer and 3.1% (2/64) in the winter. Femur fracture was only observed in 0.9% of cases of death (1/106) in the summer period. Inconclusive cases accounted for 13.2% (14/106) in the summer and 10.9% (7/64) in the winter. It was also noted that pre-slaughter mortality in both seasons of the evaluated year occurs more in pigs that are in the rest period (64.5% (139/216) than during transportation (35.5% (77/216).

This thesis focused on the dynamics of the sexual reproduction of microcrustacean Daphnia (Cladocera, Anomopoda). Sex in Daphnia is induced environmentally after rounds of asexual parthenogenesis in favorable conditions. The onset of sexual reproduction and the occurrence of sexual individuals was investigated with respect to their distribution in the water column and clonal structure. The produced sexual eggs were genotyped and their density and distribution in sediment were analyzed. The impact of massive floods was investigated. The role of sexual reproduction in stable habitats and its relevance and importance for Daphnia communities is further discussed.

Basic science and early clinical trial evidence suggest the safe diuretic drug amiloride, may exert a neuroprotective effect in multiple sclerosis (MS) through blockade of the acid sensing ion channel. Neuroprotective treatments are a key unmet need in multiple sclerosis. Optic neuritis (ON) is a discrete CNS inflammatory event leading to neuro-axonal injury in the optic nerve and retina. The optic nerve is part of the visual system, one of the most functionally and structurally eloquent systems in the central nervous system, which affords a number of unique modalities to assess neurodegeneration and neuroprotection. The visual system can be classified into two parts, the anterior and posterior visual systems, which are defined by the lateral geniculate nucleus, where the two components synapse. The extent of neurodegeneration following ON in the anterior visual system can be imaged in vivo through scanning laser polarimetry (GDx) and optical coherence tomography (OCT). The posterior visual system can be imaged by quantitative and functional magnetic resonance imaging (MRI) of the brain, giving insights into white matter structural integrity and cortical plasticity over time. Combining these modalities in a longitudinal study, allows assessment of the impact of neurodegeneration in the anterior visual system on neurodegeneration downstream in the posterior visual system and on changes in functional connectivity over time in the visual cortex. Furthermore, in the clinical trial setting the neuroprotective effect of any intervention both on direct anterior neurodegeneration and downstream processes can be assessed. The functional relevance of changes in all of these biomarkers can be tested through a number of visual measures, including low contrast visual acuity. In MS, the contribution of transsynaptic neurodegeneration to the global neuronal loss experienced by patients is an area of incomplete understanding. In addition, the role of the visual cortex, through neuroplasticity, in aiding visual recovery from optic neuritis, is unclear. To address these issues, this thesis reports the results of the first clinical trial of amiloride in ON, and shows that despite the pre- and early clinical evidence of neuroprotection of amiloride, no neuroprotective benefit was found. It goes on to explore reasons for this lack of effect including the finding of early retinal neurodegeneration in ON, and the need for early recruitment windows in the future. From there, it makes a detailed assessment of the longitudinal changes in retinal OCT for 12 months following ON, including a novel finding of the temporal evolution of inner nuclear layer swelling, previously reported only cross-sectionally. Next, for the first time macular retinal neurodegeneration is shown to influence diffusion tensor MRI derived measures of white matter integrity in the optic radiations, indicating transsynaptic neurodegeneration. Finally, longitudinal changes in resting state functional connectivity following ON are found in the visual system for the first time. The interaction between this cortical functional, retinal neurodegeneration and visual recovery is probed.