Ionic and osmotic homeostasis, and the intricately linked mechanisms of acid-base balance are critical for the survival of fish. To date, the role of the gastrointestinal (GI) tract in these processes has received only limited study, and our knowledge has been gained almost exclusively through studies conducted in fasting animals. The impacts of feeding and digestion, ubiquitous processes in the natural environment, are likely to be significant but have been overlooked. The current thesis addressed these shortfalls in our current understanding. Research focused on the rainbow trout (Oncorhynchus mykiss), a euryhaline species capable of withstanding the opposing challenges of life in seawater (diffusive influx of ions and loss of water) and freshwater (diffusive loss of ions and gain of water), and concentrated on its physiological response to ingestion of a meal of commercial, dry trout food, containing concentrated salts and little water. The net absorption and secretion of ions and water was tracked in each section of the GI tract of the rainbow trout over a detailed time course using an experimental diet that contained a simple inert marker, in the presence of external freshwater or seawater. Additionally, changes in overall blood chemistry were investigated to examine changes in osmotic, ionic and acid-base regulation during digestion. Feeding in freshwater resulted in the loss of endogenous water to the GI tract during digestion. Additionally, the meal provided much needed ions to balance those lost by diffusion; indeed all of the ingested ions were assimilated along the GI tract except for sodium which was absorbed in the stomach, but secreted in the intestine such that overall sodium balance was close to zero. Feeding also created a metabolic base load (an increase in the concentration of base, or HC03- due HCl secretion into the stomach lumen) that alkalinized the blood (i.e. caused a rise in pH), a phenomenon known as an alkaline tide. The base load was subsequently removed from the blood through increasedexcretion of base to the water via the gills. In seawater, the commercial diet again provided an avenue for water loss. This was potentially deleterious to an organism already suffering from diffusive water loss to the environment. Ion absorption from the diet was negligible, except for potassium and calcium, which were readily assimilated. As in freshwater, digestion resulted in an alkaline tide, however the mechanism of acid-base homeostasis differed with the excess base likely being excreted into the intestine. In contrast to freshwater fish, the gills took up additional base from the external environment, prolonging the acid-base disturbance in seawater fish. Overall, feeding was a dynamic process with far reaching systemic physiological effects. The research described highlighted intimate interactions between the processes of feeding and digestion and ion, water and acid-base homeostasis, and elucidated mechanisms that enable fish to inhabit a wide range of environments. / Thesis / Doctor of Philosophy (PhD)

Alzheimer's disease is the most common dementia disease and the main cause of death. The hallmark is neurofibrillary tangles (abnormal aggregates of tau protein) and beta-amyloid (Aβ) neuritic plaques that leads to impaired cognitive function such as memory loss and learning difficulties. Researchers have discovered that intermittent fasting improves these cognitive abilities, even though eating regularly is recommended for good cognition. This systematic review aims to investigate further if intermittent fasting improves cognitive function in Alzheimer’s disease and if levels of Aβ and tau pathology explain these changes in cognitive function. The research question is: does intermittent fasting improve cognitive abilities in Alzheimer’s disease and does the levels of Aβ and tau pathology explain these cognitive changes? A literature search for articles was performed on three electronic databases: Pubmed, Web of Science, and WorldCat which gave n=744 articles. The cognitive tests showed a trend toward improved memory, learning, and exploratory behavior in Alzheimer’s disease from intermittent fasting. However, the effects on the levels of Aβ and tau pathology were inconsistent, which invites the possibility of a more prominent, underlying issue of Alzheimer's disease.

Steller sea lions, the largest Otariid, fast during their breeding season; during this time they refrain from ingesting food for a period of 12-43 days. Fasting, while undertaking an extremely energetically demanding activity (breeding and pupping), requires specific physiological adaptations. This study examined the physiological response to fasting of two age classes, juveniles and sub-adults, during the breeding and non-breeding seasons to determine how these animals utilize lipids and the pattern of fatty acid mobilization from lipid stores during fasting. Four juveniles and 5 sub-adults were fasted for one and two weeks, respectively, and blood samples were collected approximately every 3 days for lipid analysis. The concentrations of plasma non-esterified fatty acids (NEFA) were analyzed spectrophotometrically. Serum fatty acid composition was analyzed using gas chromatography (GC) and their individual weight percent (wt %) were correlated with their peak retention time and calculated using the area under each peak. Sixty-nine fatty acids were quantified from each sample. However, only those with concentrations above 0.2 wt. % were included in the analysis. Sub-adult samples were grouped on a percent mass loss basis (0%, 7-8% and 15% mass loss) to facilitate comparison with the juveniles. These data represent the total lipid fatty acid composition of each blood sample. Relative lipid concentration was calculated by multiplying the total lipid fatty acid compositional analysis (wt %) by the NEFA concentrations measured in that respective blood sample. Plasma NEFA concentrations in juvenile Steller sea lions ranged from 1.2 [plus or minus] 0.51 mM to 3.7 [plus or minus] 0.69 during fasting and was within the range of fasting phocids. Concentrations of NEFAs in the sub-adult Steller sea lions ranged from 1.00 mM up to 9.70 mM and were generally higher than fasting phocids. The wt % of only one fatty acid (20:0) was significantly different between the breeding and non-breeding season in fasting juveniles. However, the wt % of seven fatty acids changed significantly during fasting in the juveniles and five of these were most significant in separating the beginning and end of the fasts using principal components analysis. In contrast, the wt % of 10 fatty acids were significantly different during the breeding and non-breeding season fasts of the sub-adults. Additionally, the wt % of 10 fatty acids changed significantly during fasting in the sub-adults and four of these (16:1n-7, 18:2n-6, 20:0, and 20:1n-9) were most significant in separating the beginning and end of the fasts using principal components analysis. These trends reveal the physiological differences between the juvenile and sub-adult Steller sea lions and suggest that the sub-adults may be better physiologically and metabolically adapted to fast than the juveniles in this study.

Background Procedural sedation and analgesia (PSA) is considered a core competency in emergency medicine as patients present to the Emergency Centre (EC) on an unscheduled basis, often complex complaints that necessitate emergent management (1). Previous evidence has consistently shown that procedural sedation and analgesia(PSA) in the EC in the paediatric population, even the very young, is safe if appropriate monitoring is performed and appropriate medications are used (2–5). The aim of the study was to describe the indications for PSA in the paediatric EC population, the fasting status of paediatric patients undergoing PSA, and the complications observed during PSA in a single Western Cape emergency centre. Methods A retrospective, descriptive study was conducted at Mitchells Plain Hospital, a district-level hospital situated in Mitchells Plain, Cape Town. All paediatric patients younger than 13 years of age who presented to the EC and received PSA during the study period (December 2020 – April 2021) were included in the study. Data was extracted from a standardised PSA form and simple descriptive statistics were used. Results A total of 116 patients (70,7% male) were included: 13 infants (<1 year of age) 48 young children (1-5 years of age) and 55 older children (5-13 years of age). There were only 2 (1,7%) complications documented, both of which were vomiting and did not require admission. The most of patients received ketamine (93,1%). The standardised PSA form was completed in 49,1% of cases. Indications for PSA included burns debridement (11,2%), suturing (17,2%), fracture reduction (23,3%), lumbar punctures (31,9%) and others (27,6%). The indications for PSA varied between the different age groups. Conclusion The study findings are in accordance with previous international literature. Emergency Centre PSA in the paediatric populations did not show an increase in interventions or complications, despite the fasting status (6). Safe, timely PSA with minimal pain and unnecessary suffering can become the norm in Emergency Medicine practice in South Africa.

Cancer is a leading cause of death in the United States and the world. Based on the literature, the side effects of prolonged use of cancer treatment pose a threat to the patient's treatment compliance and efficacy. This study aims to determine the extent to which calorie restriction and fasting can improve the efficacy of cancer treatments, tolerability of cancer treatments, and compliance with cancer treatments through a systematic review. The search for studies involved the use of key terms and extenders based on population, intervention, comparator, outcomes, and study designs (PICOS) framework including participants receiving cancer treatment, dietary interventions, and cancer treatment outcomes. All search results were uploaded to Covidence® software and two independent blinded reviewers screened the studies, and three independent reviewers extracted the data. Studies were first screened based on the title and abstract, and then they were screened based on the full text. If the synthesized data had similar characteristics and there were enough studies available, then the meta-analysis would be performed. While Riedinger et al., Voss et al., and de Groot et al. did not find any significant difference in treatment efficacy between fasting and control groups, the earlier study done by de Groot et al. showed that the effects of fasting can show significant improvement in decreasing the amount of DNA damage in noncancerous cells. Regarding the effects of fasting and calorie restriction on patient tolerability when receiving chemotherapy or radiotherapy, all studies covering the effect demonstrate a trend suggesting that there is no significant difference between the dietary intervention groups and control groups. Overall, there is not enough information from these studies to conclude the effect of fasting on treatment compliance.

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Made available in DSpace on 2016-12-23T13:56:00Z (GMT). No. of bitstreams: 1 Bermudes.pdf: 1280638 bytes, checksum: cf675a18fbda30bc9b61e74a1921a53e (MD5) Previous issue date: 2007-07-06 / Intermittent fasting is frequent in medical practice and this condition has been studied as a therapeutic intervention for some diseases. Increased life span and resistance to stress is observed in rodents submitted to intermittent fasting. However there is not much information on the evolution of infections in animals submitted to these diet manipulations. To study the evolution of fecal peritonitis in mice after 72 h fasting or after different time of intermittent fasting. After 72 h of fasting mice were submitted to cecal ligature and puncture or to an intraperitoneal injection of feces (1:6 or 1:9, weight/volume dilutions). Mice submitted to intermittent fasting, three days for two weeks or the day after the other day, during four months, received intraperitoneal injection of feces with the same dilutions. Mortality was evaluated up to 14 days, when the animals were killed to quantify the intraperitonel abscesses. The abscesses were classified with the values one, two or three according they were respectively up two, between two and five or higher than five millimeters in diameter. For each animal a score was obtained by the sum of values originated from the product of the number attributed to the abscesses versus the number of each abscess type. Control mice, paired by gender and age, were submitted to the same procedures. In mice submitted to 72 h fasting or intermittent fasting the signs of septic shock appeared earlier and were more severe, with higher mortality up to 24 h, although the global mortality evaluated by Kaplan-Meyer method was not significant after two weeks. Among the survivors the score of abscesses were significantly lower in mice submitted to fasting, mainly in groups treated with feces 1:9 dilution, in which occurred less mortality. Results demonstrate that acute or intermittent fasting increases the susceptibility to endotoxic shock and induces increased resistance to bacteria, demonstrated by reduction in number and volume of abscesses. / Jejum prolongado não é infrequente na prática médica e períodos intermitentes de jejum vêm sendo estudados como intervenção terapêutica para algumas doenças. Períodos intermitentes de jejum induzem aumento da longevidade e da resistência ao estresse em roedores. No entanto, pouco se conhece sobre o efeito dessas manipulações de dieta na evolução de infecções. Estudar a evolução de peritonite fecal em camundongos após jejum de 72 horas ou após períodos de jejuns intermitentes. Camundongos foram submetidos a jejum de 72 h e em seguida à ligadura e punção do ceco ou à injeção intra-peritoneal de fezes (diluídas a 1:6 ou a 1:9). Camundongos submetidos a jejum intermitente de três dias a cada duas semanas ou em dias alternados, durante quatro meses, foram submetidos a peritonite por injeção intra-peritoneal de fezes com as mesmas diluições. Foi avaliada a mortalidade até duas semanas, quando os animais foram sacrificados para contagem e mensuração dos abscessos intraperitoneais. Os abscessos recebiam os valores 1, 2 ou 3 conforme tivessem até 2, de 2 a 5 ou acima de 5 mm de diâmetro, respectivamente. Um escore para cada animal foi calculado pela soma dos valores obtidos da multiplicação do número de abscessos pelo valor atribuído ao seu tamanho. Animais controle, mantidos em dieta ad libitum , pareados por idade e sexo, foram submetidos aos mesmos procedimentos. Nos animais submetidos ao jejum agudo ou intermitente, as manifestações do choque séptico foram sempre mais precoces e mais graves, com maior mortalidade nas primeiras 48 h, embora nem sempre a diferença na sobrevivência (Kaplan-Meyer) tenha sido significativa. Nos sobreviventes, o escore dos abscessos era significativamente menor nos grupos submetidos a jejum, especialmente quando a peritonite fecal era induzida por injeção mais diluída de fezes (1:9), com menor mortalidade. Os resultados mostram que o jejum agudo ou o jejum intermitente aumentam a susceptibilidade ao choque endotóxico, mas aumenta resistência às bactérias, demonstrada pela menor extensão dos abscessos peritoneais formados.

Sammanfattning Bakgrund: Dagens stillasittande livsstil med ökat intag av energigivande ämnen resulterar i ett konstant anabolt hormonellt påslag. Detta leder till ökad övervikt och andra välfärdssjukdomar. Det rekommenderas att individer håller sig till en hög måltidsfrekvens med jämna mellanrum under dagen. Detta har börjat ifrågasättas med konkurrerande alternativ som involverar en tidigare samhällslivsstil så långt som 10 000 år sedan, då måltidsfrekvensen inte kunde planeras på samma sätt som idag. Syfte: Syftet är att under sju veckor undersöka effekten av två stycken veckovisa 24-timmars periodiska förbud mot intag av energigivande ämnen, med implementering av fysisk styrketräning och dess effekt på lean body mass (LBM) och fettvikt hos yngre individer. Metod: Två separata 24-timmars perioder av fasta i samband med tre separata styrketräningstillfällen genomfördes per vecka under sju veckor. Kroppsmått gällande kroppsfett i procent, fettvikt i kilogram (kg), kroppsdimensioner i centimeter (cm), LBM och total kroppsvikt i kg togs innan och efter studiens genomförande. Sju deltagare (två män och fem kvinnor) slutförde sitt deltagande i studien. Resultat: Samtliga deltagare ökade i LBM, med en medelökningen på 1,3 kg. Den största ökningen var 2,6 kg, och återfanns hos två deltagare. Samtliga deltagare minskade sitt procentuella kroppsfett. Den högsta minskningen var 4,8 %, den lägsta minskningen var 1 %. Medelminskningen i fettvikt var 2 kg hos individerna. Den största minskningen av fettvikt var 4,2 kg, och den lägsta minskningen var 0,64 kg. Slutsats: Periodisk fasta under två stycken 24-timmarsperioder per vecka kan fungera som ett verktyg för att minska fettprocent/fettvikt och samtidigt öka muskelmassan om det görs i kombination med tre stycken styrketräningstillfällen under samma vecka. Denna slutsats ifrågasätter äldre forskning och påståenden om vikten vid att hålla en hög och jämn måltidsfrekvens. / Abstract Background: Today's sedentary lifestyle with increased intake of energy giving substances results in a constant anabolic hormonal onset. This leads to increased obesity and other lifestyle diseases. It is recommended that individuals adhere to a high meal frequency at regular intervals throughout the day. This has been questioned with competing alternatives involving a former lifestyle as long as 10 000 years ago, when the meal frequency could not be planned in the same way as today. Objective: To investigate the effects of two 24 - hour periodic total restriction of consumption of energy giving substances, with the implementation of physical strength training and its effect on lean body mass (LBM) and fat mass in young individuals. Method: Two 24 hour periods of intermittent fasting in combination to three separate weight training sessions took place weekly for seven weeks. Body measurements involving body fat percentage, fat mass in kilograms (kg), body perimeters in centimeters (cm), LBM and total body weight in kg was measured before and after the study. Seven participants completed the study. The group included two men and five women (n = 7). Results: All participants increased their LBM, the mean increase was 1.3 kg. The largest increase was 2.6 kg, and was found among two of the participants. All participants reduced their body fat percentage. The highest reduction was 4.8 %, the lowest reduction was 1 %. The average decrease in fat weight was 2 kg. The largest reduction in fat weight was 4.2 kg, and the lowest reduction was 0.64 kg. Conclusion: Intermittent fasting during two separate 24-hour periods per week can serve as a tool in reducing body fat / fat mass while increasing muscle mass if done in combination with weight training three times during the same week. This finding questions the earlier research and claims about the importance of maintaining a consistently high meal frequency.