The impact of fatigue on the intermittent high intensity exercise undertaken during participation in team sports has not been extensively studied. Team sports are characterised not only by intennittent exercise, but also by the contribution of a wide range of skills. This thesis describes a series of studies conducted in a controlled environment to assess the influence of fluid ingestion and fatigue on selected soccer skills. The aim of the first study was to examine the effect of 90-min of high intensity shuttle running with and without water ingestion on a socc er-dribb ling test. The subjects were allocated to two randomly assigned trials either ingesting or abstaining from fluid intake during a 90 min intennittent exercise protocol (Loughborough Intermittent Shuttle Test: LIST). In the absence of water ingestion soccer skill deteriorated (p < 0.05) by 5% but was maintained when fluid was ingested. The principal aim of the second study was to understand further the mechanisms contributing to the deterioration observed during the LIST. Subjects completed the LIST ingesting a 6.4% carbohydrate electrolyte solution (CHO), placebo (CON) or no fluid (NON). Free fatty acids, cortisol and aldosterone responses were lower (P < 0.01) at the end of exercise during both CHO and CON in comparison to NON. There was no difference in respiratory exchange ratio between trials. Fluid ingestion did not appear to cause a shift in substrate metabolism even though there were differences in plasma FFA concentrations. The consumption of carbohydrate during exercise has been shown to increase physical performance, capacity and cognitive function. The aim of the third study was to assess the influence of a 6.4 % carbohydrate-electrolyte (CHO) placebo (CON) or no fluid (NON) on passing and dribbling soccer skills following the LIST. During the NON trial performance of the dribbling test followed a similar pattern to that in the first study and performance of the passing test decreased (p < 0.05). This reduction in performance was prevented during the CHO and CON trials. The purpose of the final study was to identify whether a rehydration strategy following the LIST would result in a recovery of skill performance. Subjects were allocated to two randomly assigned trials either ingesting a volume of fluid equivalent to 150% (L) or 9% (S) of body mass loss during the LIST, over a2h recovery period. During the recovery period serum sodium and osmolality returned to resting concentrations in the L trial but remained elevated in the S trial (P < 0.05). Despite body mass returning to resting values following the rehydration period, performance of the skills tests remained impaired. Deterioration in skill test performance may have been related to a reduction in neuromuscular control either by a reduction in muscle glycogen or by an increase in muscle damage during the no fluid trials. The mechanism responsible for the deterioration in skill performance remains to be elucidated.

Learning processes play a major role in controlling intake of food. Through repeated experiences an animal acquires the ability to predict the postingestive effects of a particular food (i.e., of its nutrients and energy) from its sensory characteristics. What is unclear from the literature, however, is whether an animal can anticipate the duration of subsequent food deprivation from predictive sensory qualities of a food, and hence increase the amount eaten of that cueing food. Therefore, the aim of this work was to investigate the characteristics of this under-researched type of learning, i.e., anticipatory eating, using laboratory rats trained on two lengths of fasting (short: 2-3 h, long: 8-10 h). The main findings were as follows. 1) Anticipatory eating is learnt when a choice is given between protein- and carbohydrate-rich foods as well as on a single balanced test food. 2) The learnt extra intake of food is instrumental to preventing the return of hunger, removal of which negative reinforcement extinguishes the response. 3) The resulting return of hunger induces re-learning of anticipatory eating. 4) During the training sessions, learning of anticipatory eating competes with classical conditioning of sensory preference. Conditioning of preference is likely to be stronger with the shorter than with the longer length of fasting. Therefore, the difference between intakes before the long and the short fast at each trial is the summed result of these two mechanisms of acquired increase in intake. While preference conditioning usually reaches a maximum rapidly, depletion-avoidance increases for as long as has been tested, with interruptions of rapid self-extinction and re-learning, This self-extinction contributes to the homeostatic character of this learning. 5) High-fat maintenance diet attenuates the learning of anticipatory eating. Overall, the findings provided robust evidence that eating in rats can be controlled by instrumental learning reinforced by hunger. Accordingly, the design of an experiment on such instrumental control of eating in human subjects is proposed to conclude this thesis.

Quantitative soil ingestion studies employing a mass balance tracer approach have been used to determine soil ingestion rate for use in human health risk assessments (HHRAs). Past studies have focused on soil ingestion in populations living in urban/suburban environments and the results have been highly variable. Moreover, there is a paucity of reliable quantitative soil ingestion data to support human health risk assessments of other lifestyles that may be predisposed to ingesting soil, such as indigenous populations following traditional lifestyles. Thus, the primary objective of the research was to determine if populations following lifestyles typical of traditional land use practices in rural or wilderness areas ingest more soil than populations living in urban or suburban environments. Further, the research investigated the use of alternative mass balance tracers, specifically isotopes of the 238U and 232Th decay series, to reduce soil ingestion estimate variability. Mass balance tracer methods were developed and validated in a pilot canine study, and methods using isotope tracers were adapted to permit quantification of sediment ingestion in the benthic fish Moxostoma macrolepidotum (Shorthead Redhorse Sucker). A pilot human soil ingestion study of 7 subjects from an Aboriginal community in British Columbia was conducted over a 3-week period. The mean soil ingestion rate calculated using the daily means of the 4 elemental tracers with the lowest food-to-soil ratios (i.e., Al, Ce, La, Si) was observed to be approximately 74 mg d-1 (standard deviation 91 mg d-1), The median soil ingestion rate was 60 mg d-1, and the 90th percentile was 196 mg d-1. These soil ingestion rate estimates are higher than those currently recommended for HHRAs of adults, and higher than those obtained in most previous studies of adults. However, the estimates are much lower than the earlier qualitative assessments for subsistence lifestyles (i.e., 330-400 mg d-1). The study results also demonstrated that isotopes of the 238U and 232Th decay series radionuclide are not reliable mass balance tracers for estimating soil ingestion in humans; however, they may be useful for quantifying soil and sediment ingestion in wildlife.

Thesis (M.Sc.)--University of Alberta, 2010. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Nutrition and Metabolism, Department of Agricultural, Life and Environmental Sciences. Title from pdf file main screen (viewed on April 28, 2010). Includes bibliographical references.

abstract: Modern gas turbines operate at high mainstream gas temperatures and pressures, which requires high durability materials. A method of preventing these hot gases from leaking into the turbine cavities is essential for improved reliability and cost reduction. Utilizing bleed-off air from the compressor to cool internal components has been a common solution, but at the cost of decreasing turbine performance. The present work thoroughly describes the complex flow field between the mainstream gas and a single rotor-stator disk cavity, and mechanisms of mainstream gas ingestion. A combined approach of experimental measurement and numerical simulation are performed on the flow in a single-stage model gas turbine. Mainstream gas ingestion into the cavity is further reduced by utilizing two axially overlapping seal rings, one on the rotor disk and the other on the stator wall. Secondary purge air is injected into the rotor-stator cavity pre-swirled through the stator radially inboard of the two seal rings. Flow field predictions from the simulations are compared against experimental measurements of static pressure, velocity, and tracer gas concentration acquired in a nearly identical model configuration. Operational conditions were performed with a main airflow Reynolds number of 7.86e4 and a rotor disk speed of 3000rpm. Additionally the rotational Reynolds number was 8.74e5 with a purge air nondimensional flow rate cw=4806. The simulation models a 1/14 rotationally periodic sector of the turbine rig, consisting of four rotor blades and four stator vanes. Gambit was used to generate the three-dimensional unstructured grids ranging from 10 to 20 million cells. Effects of turbulence were modeled using the single-equation Spalart-Allmaras as well as the realizable k-epsilon models. Computations were performed using FLUENT for both a simplified steady-state and subsequent time-dependent formulation. Simulation results show larger scale structures across the entire sector angle inside the cavity and certain unsteady mainstream ingestion mechanisms are realized from the tracer gas. Simulated velocity distributions were scrutinized against Particle Image Velocimetry plots in the rotor-stator cavity and are in reasonable agreement with all of the measurements. / Dissertation/Thesis / M.S. Engineering 2010

INTRODUÇÃO. A ingestão aguda de 500 ml de água pode elevar a pressão arterial de forma expressiva em indivíduos com disfunção autonômica, mas parece não afetar os níveis pressóricos de indivíduos jovens saudáveis. Na hipertensão arterial sistêmica podem ocorrer alterações na modulação autonômica e, em ratos hipertensos, há evidências de que a ingestão de água seja capaz de promover aumento da pressão arterial. Entretanto, em seres humanos hipertensos, os efeitos da ingestão aguda de água ainda não são conhecidos. OBJETIVOS. Avaliar os efeitos hemodinâmicos e autonômicos da ingestão aguda de água em indivíduos portadores de hipertensão arterial sistêmica, bem como investigar os mecanismos fisiológicos envolvidos na resposta pressora. MÉTODOS. Participaram do estudo 8 indivíduos portadores de hipertensão arterial sistêmica leve (idade = 42,5±7,8 anos; índice de massa corporal= 27,1±3,4 kg/cm2) e 10 indivíduos normotensos (idade = 37,3±7,5 anos; índice de massa corporal = 25,8±3,2 kg/cm2), os quais foram submetidos à ingestão de 500 ml de água após repouso na posição supina por 30 minutos. Foram avaliadas a pressão arterial (Finapress, Ohmeda), a freqüência cardíaca, o fluxo sangüíneo do antebraço, a resistência vascular do antebraço e a atividade nervosa simpática muscular no basal e aos 10, 20 e 30 minutos após a ingestão de água. Amostras sangüíneas venosas foram coletadas no basal e aos 10 e 30 minutos após a ingestão de água, para calcular as mudanças no volume plasmático. A variabilidade da pressão arterial sistólica e da freqüência cardíaca foi avaliada por análise espectral, utilizando-se a Transformação Rápida de Fourier. RESULTADOS. A ingestão de água resultou em significativo aumento máximo das pressões arteriais sistólica (Hipertensos = 19±7 mmHg; Normotensos = 17±7 mmHg, p = 0,001) e diastólica (Hipertensos = 14±4 mmHg; Normotensos = 14±5 mmHg, p = 0,001) nos indivíduos hipertensos e normotensos. Ambos os grupos também apresentaram significativa elevação máxima da resistência vascular no antebraço (Hipertensos = 19±11 unidades; Normotensos = 20±13 unidades, p = 0,001) e da atividade nervosa simpática muscular (Hipertensos = 8±2 disparos/min; Normotensos = 8±4 disparos/min, p = 0,001). RESULTADOS. Após a ingestão de água, houve redução da freqüência cardíaca (Hipertensos = - 5,6±2,1 bat/min; Normotensos = - 5,4±7,3 bat/min, p = 0,002), do fluxo sangüíneo no antebraço (Hipertensos = - 0,5±0,4 ml/min/100 ml tecidual; Normotensos = - 0,7±0,6 ml/min/100 ml tecidual, p = 0,001) e do volume plasmático (Hipertensos = - 0,8±0,8 %; Normotensos = - 1,0±0,9%, p = 0,002) nos indivíduos hipertensos e normotensos. A variabilidade da freqüência cardíaca e da pressão arterial sistólica não foi alterada pela ingestão de água. CONCLUSÃO. A ingestão aguda de água eleva similarmente as pressões arteriais sistólica e diastólica de indivíduos hipertensos leves e normotensos, provavelmente por aumento da resistência vascular periférica, secundário à ativação simpática. / Introduction. An acute water ingestion of 500 ml may significantly increase blood pressure in individuals with autonomic dysfunction. However, it doesn’t seem to influence the pressure levels of young, healthy subjects. When a systemic arterial hypertension is present, alterations can occur in the autonomic modulation mechanism, and there is scientific evidence that acute water drinking is responsible for increases in the arterial blood pressure of laboratory rats with hypertension. However, in human subjects with hypertension, the effects of an acute water ingestion are not yet well known. Objectives. The current study aims to evaluate haemodynamics and autonomic response to acute water ingestion in human subjects that have systemic arterial hypertension, as well as to study the physiological mechanisms underlying in the pressure elevation phenomena. Method. The human subjects that participated were divided up into two study groups. The first group of eight subjects, had been diagnosed with stage I systemic hypertension (ages = 42.5±7.8 years; with a body mass index = 27.1±3.4 kg/cm2), and the second group consisted of 10 subjects that had normal pressure readings (ages = 37.3±7.5 years; with a body mass index equivalent to 25.8±3.2 kg/cm2). All participants had drunk 500ml of water, after resting for 30 minutes in the supine position. The following parameters were studied: arterial blood pressure (Finapress, Ohmeda), heart rate, forearm blood flow, forearm vascular resistance and basal muscle sympathetic nerve activity after 10, 20, and 30 minutes, immediately following the acute water ingestion. Venous blood samples were collected during the basal period of 10 and 30 minutes after water drinking, in order to calculate plasmatic volume changes. Systolic pressure and heart rate variability were evaluated by spectral analysis, utilizing the Fast Fourier Transform. Results. There was a significant maximum increase in systolic and diastolic arterial pressure, in both, hypertensive and normotensive human subjects, as a direct consequence of acute water ingestion. Systolic pressure increase was of 19±7 mmHg, in hypertensive subjects; while the same pressure increase was of 17±7 mmHg, for normotensive subjects, (p = 0.001). Similarly, the diastolic pressure increase in hypertensive subjects had an equivalent to 14±4 mmHg, and in normotensive subjects showed an increase equivalent to 14±5 mmHg, (p = 0.001). Similarly, the diastolic pressure increase in hypertensive subjects had an equivalent to 14±4 mmHg, and in normotensive subjects showed an increase equivalent to 14±5 mmHg, (p = 0.001). Also, both groups presented a significant maximum increase in forearm vascular resistance (Hypertensive = 19±11 units; normotensive = 20±13 units, p = 0.001) and in muscle sympathetic nerve activity (Hypertensive = 8±2 bursts/min, normotensive = 8±4 bursts/min, p = 0.001). After acute water ingestion, both, hypertensive and normotensive human subjects showed a decreased heart rate, forearm blood flow, and plasmatic volume. The heart rate decrease in hypertensive subjects was equal to - 5.6±2.1 beats/min; and for normotensive subjects was = - 5.4±7.3 beats/min, (p = 0.002), the forearm blood flow decrease in hypertensive subjects was = - 0.5±0.4 ml/min/100 ml tissue, and in normotensive subjects was = - 0.7±0.6 ml/min/100 ml tissue, (p = 0.001), and the plasmatic volume drop in hypertensive subjects was = - 0.8±0.8 %; and for normotensive subjects was = - 1.0±0.9%, (p = 0.002). Heart rate and systolic arterial pressure variability were not altered by acute water ingestion. CONCLUSION. An acute water ingestion equally increases systolic and diastolic arterial pressure in human subjects with stage I hypertension, as well as those normotensive ones, probably by increasing peripheral vascular resistance, which is secondary to sympathetic activity.

Made available in DSpace on 2014-06-11T19:31:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-30Bitstream added on 2014-06-13T19:20:16Z : No. of bitstreams: 1 vasconcellos_rs_dr_jabo.pdf: 400530 bytes, checksum: 7196fccd434d8abdaab7968a17d958ce (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetiva-se com o tratamento da obesidade em gatos a redução de massa corporal gorda com mínima perda de massa magra, bem como o fornecimento de nutrientes em quantidade suficiente para manter a saúde dos animais durante a perda de peso e favorecer a manutenção do peso após o término do regime. A elevação nas concentrações de proteína em dietas para perda de peso tem se mostrado benéfica em muitas espécies. Neste trabalho foram avaliadas duas rações com diferentes concentrações de proteína bruta na perda de 20% do peso corporal e subseqüente manutenção do peso em gatos. Constituíram-se dois grupos, sendo um grupo controle (Co; n=8), que recebeu dieta com 29% de proteína e outro que recebeu dieta com 42% de proteína, denominado alta proteína (AP; n=7). As características da perda de peso em machos (n=8) e fêmeas (n=7) também foram avaliadas. Composição corporal (DXA), ingestão de energia metabolizável (EM), concentrações hormonais e bioquímicas séricas e balanço de nitrogênio dos animais foram quantificadas durante a perda de peso. Houve perda de massa magra (MM) no grupo Co (p<0,05), mas não no grupo AP (p>0,05) durante o emagrecimento. Embora não tenha sido encontrada diferença na taxa de perda de peso, a dieta AP possibilitou maior ingestão calórica (EM/kg de peso0,4) que Co para se atingir igual emagrecimento semanal. Houve redução (p<0,05) na leptinemia ao longo da perda de peso, em ambos os grupos, sem outras alterações hormonais detectáveis. Após a perda de peso, os animais foram introduzidos numa fase de manutenção do peso (MAN) por 17 semanas. Ambos os grupos passaram a receber um mesmo alimento hipocalórico, em quantidade suficiente para manter o peso corporal. Os gatos que receberam maior quantidade de proteína durante a perda de peso (AP) apresentaram maior necessidade energética que Co durante a MAN (p<0,001)... / Treatment of cat obesity aims to minimize the loss of lean body mass, to supply nutrient quantities sufficient for maintaining animal health during weight loss and to facilitate weight loss maintenance once dieting is completed. Elevated protein concentrations in weight loss diets have shown to be beneficial for many species. In this study, two diets with differing crude protein concentrations (29% versus 42%) were evaluated for 20% weight loss and subsequent weight loss maintenance in cats. A control group (Co; n=8) received the 29% protein diet while another group, denominated high protein (HP; n=7), received the 42% diet. Weight loss characteristics of males (n=8) and females (n=7) were also evaluated. Body composition (DXA), ingestion of metabolizable energy (ME), hormonal and biochemical serum concentrations and nitrogen balance of the animals were quantified during the weight loss period. The lean mass (LM) loss observed for Co group (p<0.05) during weight reduction was not observed for HP group (p>0.05). HP diet allowed a greater cat caloric ingestion (ME/kg body weight0.4) to maintain the same weekly weight loss than Co group (p<0.05). There was a reduction (p<0.05) in leptin throughout the weight loss period in both groups. After weight loss, animals began a of 17 weeks phase of weight loss maintenance (MAN). Both groups were fed a same commercial hypocaloric food, in quantity sufficient to maintain body weight. Cats of the HP group presented a greater energy requirement during to stabilize body weight after regimen (p<0.001). There were no differences in body composition parameters between the two groups at the end of MAN (p>0.05). Males presented greater LM and less body fat, and required more ME to achieve the same weight loss rate than females (p<0.001). It was concluded that, for cats, HP diet aided LM maintenance during weight loss and allowed for greater caloric ingestion ...(Complete abstract click electronic access below)

Made available in DSpace on 2014-06-11T19:33:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-01-29Bitstream added on 2014-06-13T18:45:24Z : No. of bitstreams: 1 takahashi_ls_dr_jabo.pdf: 517174 bytes, checksum: 985878650e2da31402982268bb014e75 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A adoção de esquemas de alimentação com restrição e realimentação para peixes pode induzir a ocorrência de ganho de peso compensatório e permite redução no fornecimento de ração, principal componente do custo de produção. Além disto, o uso de dietas que forneça os nutrientes necessários para esta fase de rápido crescimento e o não comprometimento da resistência imunológica do peixe, representam vantagens adicionais. Nesse sentido, juvenis de pacu Piaractus mesopotamicus (36,9 l 2,8 g) foram submetidos a três estratégias de alimentação (alimentação continua; 3 dias restrição e 3 dias de realimentação controlada; 3 dias restrição e 3 dias de realimentação até a saciedade aparente) com duas dietas experimentais (45 e 52% CHO). Foram avaliados o desempenho produtivo e metabolismo energético em duas etapas, aos 36 e aos 84 dias de alimentação. Após os 84 dias, os peixes foram submetidos à infestação pelo parasito Dolops carvalhoi, sendo avaliadas as respostas fisiológicas de estresse. Ocorreu ingestão compensatória, tanto durante os 36 como durante os 84 dias, mas sem ocorrência de ganho de peso compensatório. Os parâmetros do metabolismo energético, aos 36 dias de alimentação, sugerem grande capacidade do pacu em mobilizar as reservas energéticas endógenas. Aos 84 dias, os parâmetros fisiológicos do metabolismo energético, evidenciam a habilidade do pacu em manter a homeostase e recuperar-se da privação alimentar através da dinâmica de suas reservas. As estratégias de alimentação adotas associadas as dietas experimentais não comprometeram as respostas do pacu frente ao desafio com o ectoparasito. A adoção de períodos curtos de restrição e realimentação, pode ser recomendada em condições específicas de manejo, sem prejuízo irreversível aos peixes e com redução nos custos de produção. / Schemes of food restriction and refeeding can induce compensatory growth in fish and reduction of production costs. Additionally, the use of diets providing needed nutrients for the fast growth and adequate immune status of fish can be beneficial. In this way, pacu juveniles Piaractus mesopotamicus (36.9 l 2.8 g) were submitted to three feed strategies (continuous feeding; 3 days of restriction and 3 days of controlled refeeding; 3 days of restriction and 3 days of refeeding until apparent satiation) and two experimental diets (45 and 52% carbohydrate - CHO). Growth performance and energetic metabolism were evaluated at 36 and 84 days of feeding. After 84 days, fish were exposed to Dolops carvalhoi, and physiological responses were evaluated. Compensatory food intake was registered at 36 and 84 days, without compensatory growth. At 36 days of feeding, metabolic indicators suggested that pacu is able to mobilize endogenous energy stores. At 84 days od food restriction, pacu exhibited ability to keep its body homeostasis by mobilizing endogenous reserves, and to recover the tissue losses provoked by food restriction. Feed strategies and experimental diets did not affect the ability of pacu to face the parasite infestation. Cycles of food restriction and refeeding for short periods (3 days restriction/3 days refeeding) can be recommended for pacu in specific conditions, since no irreversible biological damage was detected and, in addition, reduction of production cost is possible.

INTRODUÇÃO. A ingestão aguda de 500 ml de água pode elevar a pressão arterial de forma expressiva em indivíduos com disfunção autonômica, mas parece não afetar os níveis pressóricos de indivíduos jovens saudáveis. Na hipertensão arterial sistêmica podem ocorrer alterações na modulação autonômica e, em ratos hipertensos, há evidências de que a ingestão de água seja capaz de promover aumento da pressão arterial. Entretanto, em seres humanos hipertensos, os efeitos da ingestão aguda de água ainda não são conhecidos. OBJETIVOS. Avaliar os efeitos hemodinâmicos e autonômicos da ingestão aguda de água em indivíduos portadores de hipertensão arterial sistêmica, bem como investigar os mecanismos fisiológicos envolvidos na resposta pressora. MÉTODOS. Participaram do estudo 8 indivíduos portadores de hipertensão arterial sistêmica leve (idade = 42,5±7,8 anos; índice de massa corporal= 27,1±3,4 kg/cm2) e 10 indivíduos normotensos (idade = 37,3±7,5 anos; índice de massa corporal = 25,8±3,2 kg/cm2), os quais foram submetidos à ingestão de 500 ml de água após repouso na posição supina por 30 minutos. Foram avaliadas a pressão arterial (Finapress, Ohmeda), a freqüência cardíaca, o fluxo sangüíneo do antebraço, a resistência vascular do antebraço e a atividade nervosa simpática muscular no basal e aos 10, 20 e 30 minutos após a ingestão de água. Amostras sangüíneas venosas foram coletadas no basal e aos 10 e 30 minutos após a ingestão de água, para calcular as mudanças no volume plasmático. A variabilidade da pressão arterial sistólica e da freqüência cardíaca foi avaliada por análise espectral, utilizando-se a Transformação Rápida de Fourier. RESULTADOS. A ingestão de água resultou em significativo aumento máximo das pressões arteriais sistólica (Hipertensos = 19±7 mmHg; Normotensos = 17±7 mmHg, p = 0,001) e diastólica (Hipertensos = 14±4 mmHg; Normotensos = 14±5 mmHg, p = 0,001) nos indivíduos hipertensos e normotensos. Ambos os grupos também apresentaram significativa elevação máxima da resistência vascular no antebraço (Hipertensos = 19±11 unidades; Normotensos = 20±13 unidades, p = 0,001) e da atividade nervosa simpática muscular (Hipertensos = 8±2 disparos/min; Normotensos = 8±4 disparos/min, p = 0,001). RESULTADOS. Após a ingestão de água, houve redução da freqüência cardíaca (Hipertensos = - 5,6±2,1 bat/min; Normotensos = - 5,4±7,3 bat/min, p = 0,002), do fluxo sangüíneo no antebraço (Hipertensos = - 0,5±0,4 ml/min/100 ml tecidual; Normotensos = - 0,7±0,6 ml/min/100 ml tecidual, p = 0,001) e do volume plasmático (Hipertensos = - 0,8±0,8 %; Normotensos = - 1,0±0,9%, p = 0,002) nos indivíduos hipertensos e normotensos. A variabilidade da freqüência cardíaca e da pressão arterial sistólica não foi alterada pela ingestão de água. CONCLUSÃO. A ingestão aguda de água eleva similarmente as pressões arteriais sistólica e diastólica de indivíduos hipertensos leves e normotensos, provavelmente por aumento da resistência vascular periférica, secundário à ativação simpática. / Introduction. An acute water ingestion of 500 ml may significantly increase blood pressure in individuals with autonomic dysfunction. However, it doesn’t seem to influence the pressure levels of young, healthy subjects. When a systemic arterial hypertension is present, alterations can occur in the autonomic modulation mechanism, and there is scientific evidence that acute water drinking is responsible for increases in the arterial blood pressure of laboratory rats with hypertension. However, in human subjects with hypertension, the effects of an acute water ingestion are not yet well known. Objectives. The current study aims to evaluate haemodynamics and autonomic response to acute water ingestion in human subjects that have systemic arterial hypertension, as well as to study the physiological mechanisms underlying in the pressure elevation phenomena. Method. The human subjects that participated were divided up into two study groups. The first group of eight subjects, had been diagnosed with stage I systemic hypertension (ages = 42.5±7.8 years; with a body mass index = 27.1±3.4 kg/cm2), and the second group consisted of 10 subjects that had normal pressure readings (ages = 37.3±7.5 years; with a body mass index equivalent to 25.8±3.2 kg/cm2). All participants had drunk 500ml of water, after resting for 30 minutes in the supine position. The following parameters were studied: arterial blood pressure (Finapress, Ohmeda), heart rate, forearm blood flow, forearm vascular resistance and basal muscle sympathetic nerve activity after 10, 20, and 30 minutes, immediately following the acute water ingestion. Venous blood samples were collected during the basal period of 10 and 30 minutes after water drinking, in order to calculate plasmatic volume changes. Systolic pressure and heart rate variability were evaluated by spectral analysis, utilizing the Fast Fourier Transform. Results. There was a significant maximum increase in systolic and diastolic arterial pressure, in both, hypertensive and normotensive human subjects, as a direct consequence of acute water ingestion. Systolic pressure increase was of 19±7 mmHg, in hypertensive subjects; while the same pressure increase was of 17±7 mmHg, for normotensive subjects, (p = 0.001). Similarly, the diastolic pressure increase in hypertensive subjects had an equivalent to 14±4 mmHg, and in normotensive subjects showed an increase equivalent to 14±5 mmHg, (p = 0.001). Similarly, the diastolic pressure increase in hypertensive subjects had an equivalent to 14±4 mmHg, and in normotensive subjects showed an increase equivalent to 14±5 mmHg, (p = 0.001). Also, both groups presented a significant maximum increase in forearm vascular resistance (Hypertensive = 19±11 units; normotensive = 20±13 units, p = 0.001) and in muscle sympathetic nerve activity (Hypertensive = 8±2 bursts/min, normotensive = 8±4 bursts/min, p = 0.001). After acute water ingestion, both, hypertensive and normotensive human subjects showed a decreased heart rate, forearm blood flow, and plasmatic volume. The heart rate decrease in hypertensive subjects was equal to - 5.6±2.1 beats/min; and for normotensive subjects was = - 5.4±7.3 beats/min, (p = 0.002), the forearm blood flow decrease in hypertensive subjects was = - 0.5±0.4 ml/min/100 ml tissue, and in normotensive subjects was = - 0.7±0.6 ml/min/100 ml tissue, (p = 0.001), and the plasmatic volume drop in hypertensive subjects was = - 0.8±0.8 %; and for normotensive subjects was = - 1.0±0.9%, (p = 0.002). Heart rate and systolic arterial pressure variability were not altered by acute water ingestion. CONCLUSION. An acute water ingestion equally increases systolic and diastolic arterial pressure in human subjects with stage I hypertension, as well as those normotensive ones, probably by increasing peripheral vascular resistance, which is secondary to sympathetic activity.

abstract: Gas turbine efficiency has improved over the years due to increases in compressor pressure ratio and turbine entry temperature (TET) of main combustion gas, made viable through advancements in material science and cooling techniques. Ingestion of main combustion gas into the turbine rotor-stator disk cavities can cause major damage to the gas turbine. To counter this ingestion, rim seals are installed at the periphery of turbine disks, and purge air extracted from the compressor discharge is supplied to the disk cavities. Optimum usage of purge air is essential as purge air extraction imparts a penalty on turbine efficiency and specific fuel consumption. In the present work, experiments were conducted in a newly constructed 1.5-stage axial flow air turbine featuring vanes and blades to study main gas ingestion. The disk cavity upstream of the rotor, the 'front cavity', features a double seal with radial clearance and axial overlap at its rim. The disk cavity downstream of the rotor, the 'aft cavity', features a double seal at its rim but with axial gap. Both cavities contain a labyrinth seal radially inboard; this divides each disk cavity into an 'inner cavity' and a 'rim cavity'. Time-averaged static pressure at various locations in the main gas path and disk cavities, and tracer gas (CO2) concentration at different locations in the cavities were measured. Three sets of experiments were carried out; each set is defined by the main air flow rate and rotor speed. Each of the three sets comprises of four different purge air flow rates, low to high. The mass flow rate of ingested main gas into the front and aft rim cavities is reported at the different purge air flow rates, for the three experiment sets. For the present stage configuration, it appears that some ingestion persisted into both the front and aft rim cavities even at high purge air flow rates. On the other hand, the front and aft inner cavity were completely sealed at all purge flows. / Dissertation/Thesis / Masters Thesis Engineering 2015