Este trabalho descreve o planejamento, desenvolvimento e validação de um modelo de software educacional. O aplicativo é um ambiente multimídia de ensino e aprendizagem do Metabolismo dos Glicídios e o Ciclo de Krebs, denominado e-Metabolismo: Glicídios e contém um jogo de seqüência para o ensino de Bioquímica, denominado Diagrama Metabólico Dinâmico Virtual. O estudo de teorias pedagógicas e a experiência em aulas com os alunos do curso de medicina da Fundação Faculdade Federal de Ciências Médicas de Porto Alegre apontou a necessidade de mudanças no ensino de Bioquímica com uso das novas tecnologias de informação e comunicação. A justificativa do uso de um jogo virtual como método de ensino tem por base os resultados obtidos com o uso de um jogo de seqüência lógica em tabuleiro, na Disciplina de Bioquímica. O desenvolvimento do e-Metabolismo: Glicídios, tendo como referência a prática pedagógica baseada na epistemologia genética Jean Piaget, incluiu no seu planejamento a escolha de ferramenta de programação para permitir a interação do usuário (aluno) com o ambiente. O produto utiliza amplamente recursos de multimídia e pode ser disponibilizado num servidor ou em forma de CD-ROM. O ambiente virtual possibilita a interação do aluno com o ambiente e com colegas e professores através de ferramentas como, por exemplo, acesso a e-mails, chats, fóruns, mapas conceituais e diário de bordo. Instrumentos de avaliação de software foram estudados e aplicados com alunos de Disciplinas de Bioquímica no sentido de validar o software e-Metabolismo tanto no que se refere aos aspectos técnicos como a aprendizagem do conteúdo pelos alunos. Experiências com o uso do software foram, primeiramente, realizadas com alunos do curso de Medicina da FFFCMPA e depois com alunos de outros cursos. O primeiro grupo de alunos que avaliaram o e-Metabolismo foi formado pelos monitores da Disciplina. Mapas conceituais, testes escritos e avaliação dos registros deixados pelos usuários no próprio software foram utilizados como instrumentos de avaliação do conhecimento dos alunos. O grau de satisfação com o uso do método de estudo, foi avaliado por um questionário, cujas respostas foram analisadas e categorizadas. Os resultados obtidos indicam que o ambiente apresenta interface de fácil acesso, desperta o interesse, possibilita ao aluno escolher de que maneira quer fazer o seu estudo sem prejuízos no seu desempenho e facilita o estudo, sendo, portanto, considerado válido como instrumento educacional. Por se tratar de um ambiente dinâmico, deve ser constantemente atualizado, e a versão atual contém as modificações sugeridas por professores e alunos, facilitando o uso na Internet e o acompanhamento do aluno. / This work describes the planing, the development and the validation of a game-like educational software. This multimedia ambient was designed for the study of carbohydrates metabolic pathways and the Krebs's Cycle, called e-Metabolism: carbohydrates, and contains the sequential game, called Virtual Dynamic Metabolic Diagram. The study of pedagogical theories and experiments in classroom with medicine students of the “Fundação Faculdade Federal de Ciências Médicas de Porto Alegre”, pointed the necessity of changes in Biochemistry courses, involving new technologies of information and communication. The use of a game-like software as a tool for teaching is based on experiments related to the use of tray games at Biochemistry courses. The development of the e-Metabolism took as a reference the integrationists’ pedagogical practice, based on Jean Piaget's concepts, related to genetic epistemology and constructivism, yet allowing the professors to choose the teaching method they wish to use. This product integrates multimedia resources extensively, and can be used in computer networks or in the format of a CD-ROM. In the virtual environment students will be able to interact with the environment as well as with classmates and professors through such tools as chats, forums, concept maps and notepads. Software ’s evaluation Instruments were studied and applied with undergraduate students of Biochemistry classes in the way to value the eMetabolism software in its technical aspects and student’s content learning aspects. Conceptual maps, written tests and evaluation of user’s registers realized with this software where used as evaluation instruments of students knowledge. The level of satisfaction was evaluated by a questionnaire, which answers had been analyzed and categorized. The results show that the e-Metabolism is easy to use, awakes the interest and facilitates the study, improving the student performance and can be considered a valid educational instrument. Since this is a dynamic ambient and is constantly actualized, the current version contains the changes suggested by teachers and students, making easier to use it at the Internet and to do a better analysis of the student’s learning.

Vernonia herbacea, Asteraceae, possui órgãos subterrâneos de reserva ramificados, os rizóforos, que acumulam frutanos do tipo inulina como carboidratos de reserva. Os frutanos são polímeros de frutose que são sintetizados pelas enzimas SST (sacarose: sacarose frutosiltransferase) e FFT (frutano:frutano frutosiltransferase) e despolimerizados pela FEH (frutano exohidrolase). Plantas desta espécie entram em dormência no final do outono, quando perdem os ramos aéreos e rebrotam na primavera seguinte; subseqüentemente ocorre a floração e o crescimento vegetativo no verão; ocorrem variações no teor e na composição dos frutanos durante o ciclo fenológico das plantas. O rizóforo apresenta crescimento geotrópico positivo, cujo ápice apresenta tecidos mais jovens em crescimento e a rebrota dos novos órgãos aéreos se dá pelo desenvolvimento das gemas situadas na região proximal do rizóforo, localizada próximo à superfície do solo. Considerando estas variações este trabalho visou à análise da distribuição espacial das atividades da SST, FFT, Invertase e FEH, bem do teor e composição dos frutanos nas regiões proximal, mediana e distal dos rizóforos de plantas de Vernonia herbacea, em diferentes fases de desenvolvimento e em plantas induzidas à brotação pela remoção dos órgãos aéreos. Também foram analisados esses parâmetros em plantas na fase vegetativa com os órgãos aéreos intactos ou excisados, mantidas em condições ambientais naturais ou em baixa temperatura. De maneira geral, as enzimas SST e FFT apresentaram atividades mais elevadas em plantas na fase vegetativa, enquanto a FEH apresentou atividade mais elevada em plantas na fase de brotação natural ou induzida e nos tratamentos sob baixa temperatura. Com relação à distribuição espacial das atividades enzimáticas, a SST e FFT apresentaram atividade mais elevada na região distal, que diminuiu no sentido proximal dos rizóforos. A FEH por sua vez apresentou atividade mais elevada na região proximal, diminuindo no sentido distal. Em geral, o conteúdo de fruto-oligossacarídeos foi mais elevado na região distal e diminuiu em direção à região proximal dos rizóforos. Os tratamentos com baixa temperatura levaram a uma maior proporção de frutooligossacarídeos, enquanto nas plantas induzidas à brotação, a proporção de fruto-polissacarídeos foi superior. Os menores valores de grau de polimerização médio (GP) das cadeias de frutanos foram detectados na região distal, sugerindo que as cadeias de frutanos nesses tecidos não apresentam o GP característico da espécie. Valores elevados de GP foram detectados na região proximal, e valores mais elevados ainda, em plantas na fase de brotação e sob baixa temperatura, coincidindo com atividades mais elevadas de FEH. Estes resultados sugerem que o mecanismo de ação da FEH em V. herbacea seja do tipo “single chain”, pelo qual uma molécula da enzima se liga à cadeia de frutano degradando-a até a molécula de sacarose. Os experimentos realizados possibilitaram algumas deduções a respeito do mecanismo de ação das enzimas envolvidas no metabolismo de frutanos, e um maior conhecimento sobre a dinâmica de variação temporal e espacial destes carboidratos, em diferentes fases de desenvolvimento das plantas e em condições adversas ao desenvolvimento vegetal. / Vernonia herbacea, Asteraceae, bears branched underground reserve organs, rhizophores, that accumulate inulin-type fructans as reserve carbohydrates. Fructans are fructose polymers, that are synthesized by SST (sucrose: sucrose fructosyltransferase) and FFT (fructan:fructan frutosyltransferase) and mobilized by FEH (fructan exohydrolase). Plants of this species enter dormancy at the end of autumn, with senescence and abscission of the aerial organs and sprout in the following spring; flowering occurs subsequently followed by a period of vegetative growth in the summer. The concentration and composition of fructans vary during the phenological cycle of the plants. Considering this variation in fructans, and the positive geotropic growth of the rhizophores, with the apex presenting younger tissues (distal region) and the resprouting of the new aerial organs occurring in the opposite end of the organ (proximal region), close to the soil surface, the aim of this work was to analyze the spatial distribution of fructans and fructan metabolizing enzymes in the different regions of the rhizophores (distal, median and proximal) in plants of Vernonia herbacea in different developmental phases and plants induced to sprouting by the excision of the aerial organs. These parameters were also analyzed in intact plants in the vegetative phase and in excised plants, kept in natural environmental conditions or in low temperature. In general SST and FFT presented higher activities in plants in the vegetative phase, while FEH presented higher activity during sprouting, either under natural or induced sprouting and in plants under low temperature. Concerning the spatial distribution of the enzyme activities, SST and FFT presented higher activity in the distal region, decreasing towards the proximal region of the rhizophores. The FEH, on the other hand, presented higher activity in the proximal region, decreasing towards the distal region. In general, the content of fructo-oligosaccharides in the phenological phases studied was higher in the distal region and decreased towards the proximal region of the rhizophores. Low temperature led to a higher proportion of fructo-oligosaccharides, while in plants induced to sprouting the proportion of fructo-polysaccharides was higher. The lower values of average degree of polymerization (DP) of fructans chains were detected in the distal region. This indicates that fructan chain length in younger tissues is shorter then that characteristic of the species. Higher values of mean DP were detected in the proximal region and even higher DP was detected in this region in sprouting plants and in plants under low temperature, coinciding with the higher FEH activity detected in these conditions. These results suggest a mechanism of action for the FEH in V. herbacea of the "single chain" type, in which a molecule of the enzyme binds to the fructan chain degrading it completely before binding to the next fructan molecule. These studies allowed us to draw several conclusions regarding the mechanism of action of enzymes involved in the metabolism of fructans in Vernonia herbacea and regarding the dynamics of distribution of these carbohydrates and the related enzymes in different phases of development and in adverse conditions for plant development.

Current agriculture is facing a serious challenge of decreasing precipitation and irregular occurrence of drought periods including their unfavorable distribution during the vegetation season. This leads to growing interest in planting highly drought-resistant crops like sorghum. In comparison with other crops, sorghum excels in low water demand, though exhibits high susceptibility to low temperatures, which hampers its spread to new regions. Surprisingly, there is not enough information about the nature of sorghum's reaction to cold exposure. The aim of this diploma thesis was to describe reactions of young sorghum plants exposed to cold stress, low water availability and their combination and to verify the possibility of plant hardening through previous low-stress load. The special focus was paid to changes in carbohydrate metabolism, which plays generally very important role in plant defense reactions. The other analyzed physiological traits were leaf tissue osmotic potential, proline content and basic morphometric characteristics. Experimental design consisted of pot experiments conducted in growth chambers and the experiments performed under controlled conditions in vitro, using two sorghum genotypes "Ruzrok" and "01Z1800012". Both genotypes exhibited similar response to stress treatment....

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

Motivation: The prevalence of non-communicable diseases such as diabetes mellitus (DM) and cardiovascular disease (CVD) is rapidly increasing in industrialized societies. Experts believe that lifestyle, and in particular its nutritional aspects, plays a decisive role in increasing the burden of these chronic conditions. Dietary habits would, therefore, be modified to exert a positive impact on the prevention and treatment of chronic diseases of lifestyle. It is believed that the state of hyperglycaemia that is observed following food intake under certain dietary regimes contributes to the development of various metabolic conditions. This is not only true for individuals with poor glycaemic control such as some diabetics, but could also be true for healthy individuals. It would, therefore, be helpful to be able to reduce the amplitude and duration of postprandial hyperglycaemia. Selecting the correct type of carbohydrate (CHO) foods may produce less postprandial hyperglycaemia, representing a possible strategy in the prevention and treatment of chronic metabolic diseases. At the same time, a key focus of sport nutrition is the optimal amount of CHO that an athlete should consume and the optimal timing of consumption. The most important nutritional goals of the athlete are to prepare body CHO stores pre-exercise, provide energy during prolonged exercise and restore glycogen stores during the recovery period. The ultimate aim of these strategies is to maintain CHO availability to the muscle and central nervous system during prolonged moderate to high intensity exercise, since these are important factors in exercise capacity and performance. However, the type of CHO has been studied less often and with less attention to practical concerns than the amount of CHO. The glycaemic index (GI) refers to the blood glucose raising potential of CHO foods and, therefore, influences secretion of insulin. In several metabolic disorders, secretion of insulin is inadequate or impossible, leading to poor glycaemic control. It has been suggested that low GI diets could potentially contribute to a significant improvement of the conditions associated with poor glycaemic control. Insulin secretion is also important to athletes since the rate of glycogen synthesis depends on insulin due to it stimulatory effect on the activity of glycogen synthase. Objectives: Three main objectives were identified for this study. The first was to conduct a meta-analysis of the effects of the GI on markers for CHO and lipid metabolism with the emphasis on randomised controlled trials (RCT's). Secondly, a systematic review was performed to determine the strength of the body of scientific evidence from epidemiological studies combined with RCT's to encourage dieticians to incorporate the GI concept in meal planning. Finally, a systematic review of the effect of the GI in sport performance was conducted on all available literature up to date to investigate whether the application of the GI in an athlete's diet can enhance physical performance. Methodology: For the meta-analysis, the search was for randomised controlled trials with a cross-over or parallel design published in English between 1981 and 2003, investigating the effect of low GI vs high GI diets on markers of carbohydrate and lipid metabolism. The main outcomes were serum fructosamine, glycosylated haemoglobin (HbA1c), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), total cholesterol (TC) and triacylglycerols (TG). For the systematic review, epidemiological studies as well as RCT's investigating the effect of LGI vs HGI diets on markers for carbohydrate and lipid metabolism were used. For the systematic review on the effect of the GI on sport performance, RCT's with either a cross-over or parallel design that were published in English between January 1981 and September 2004 were used. All relevant manuscripts for the systematic reviews as well as meta-analysis were obtained through a literature search on relevant databases such as the Cochrane Central Register of Controlled Trials, MEDLINE (1981 to present), EMBASE, LILACS, SPORTDiscus, ScienceDirect and PubMed. This thesis is presented in the article format. Results and conclusions of the individual manuscripts: For the meta-analysis, literature searches identified 16 studies that met the strict inclusion criteria. Low GI diets significantly reduced fructosamine (p<0.05), HbA1c, (p<0.03), TC(p<0.0001) and tended to reduce LDL-c (p=0.06) compared to high GI diets. No changes were observed in HDL-c and TG concentrations. Results from this meta analysis, therefore, support the use of the GI concept in choosing CHO-containing foods to reduce TC and improve blood glucose control in diabetics. The systematic review combined the results of the preceding meta-analysis and results from epidemiological studies. Prospective epidemiological studies showed improvements in HDL-c concentrations over longer time periods with low GI diets vs. high GI diets, while the RCT's failed to show an improvement in HDL-c over the short-term. This could be attributed to the short intervention period during which the RCT's were conducted. Furthermore, epidemiological studies failed to show positive relationships between LDL-c and TC and low GI diets, while RCT's reported positive results on both these lipids with low GI diets. However, the epidemiological studies, as well as the RCT's showed positive results with low GI diets on markers of CHO metabolism. Taken together, convincing evidence from RCT's as well as epidemiological studies exists to recommend the use of low GI diets to improve markers of CHO as well as of lipid metabolism. 3 From the systematic review regarding the GI and sport performance it does not seem that low GI pre-exercise meals provide any advantages over high GI pre-exercise meals. Although low GI pre-exercise meals may better maintain CHO availability during exercise, low GI pre-exercise meals offer no added advantage over high GI meals regarding performance. Furthermore, the exaggerated metabolic responses from high GI compared to low GI CHO seems not be detrimental to exercise performance. However, athletes who experience hypoglycaemia when consuming CHO-rich feedings in the hour prior to exercise are advised to rather consume low GI pre-exercise meals. No studies have been reported on the GI during exercise. Current evidence suggests a combination of CHO with differing Gl's such as glucose (high GI), sucrose (moderate GI) and fructose (low GI) will deliver the best results in terms of exogenous CHO oxidation due to different transport mechanisms. Although no studies are conducted on the effect of the GI on short-term recovery it is speculated that high GI CHO is most effective when the recovery period is between 0-8 hours, however, evidence suggests that when the recovery period is longer (20-24 hours), the total amount of CHO is more important than the type of CHO. Conclusion: There is an important body of evidence in support of a therapeutic and preventative potential of low GI diets to improve markers for CHO and lipid metabolism. By substituting high GI CHO-rich with low GI CHO-rich foods improved overall metabolic control. In addition, these diets reduced TC, tended to improve LDL-c and might have a positive effect over the long term on HDL-c. This confirms the place for low GI diets in disease prevention and management, particularly in populations characterised by already high incidences of insulin resistance, glucose intolerance and abnormal lipid levels. For athletes it seems that low GI pre-exercise meals do not provide any advantage regarding performance over high GI pre-exercise meals. However, low GI meals can be recommended to athletes who are prone to develop hypoglycaemia after a CHO-rich meal in the hour prior to exercise. No studies have been reported on the effect of the GI during exercise. However, it has been speculated that a combination of CHO with varying Gl's deliver the best results in terms of exogenous CHO oxidation. No studies exist investigating the effect of the GI on short-term recovery, however, it is speculated that high GI CHO-rich foods are suitable when the recovery period is short (0-8 h), while the total amount rather than the type of CHO is important when the recovery period is longer (20-24 h). Therefore, the GI is a scientifically based tool to enable the selection of CHO-containing foods to improve markers for CHO and lipid metabolism as well as to help athletes to prepare optimally for competitions. Recommendations: Although a step nearer has been taken to confirm a place for the GI in human health, additional randomised, controlled, medium and long-term studies as well as more epidemiological studies are needed to investigate further the effect of low GI diets on LDL-c. HDL-c and TG. These studies are essential to investigate the effect of low GI diets on endpoints such as CVD and DM. This will also show whether low GI diets can reduce the risk of diabetic complications such as neuropathy and nephropathy. Furthermore, the public at large must be educated about the usefulness and application of the GI in meal planning. For sport nutrition, randomised controlled trials should be performed to investigate the role of the GI during exercise as well as in sports of longer duration such as cricket and tennis. More studies are needed to elucidate the short-term effect of the GI post-exercise as well as to determine the mechanism of lower glycogen storage with LGI meals post-exercise. / Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.

Orientador: Dora Maria Grassi Kassisse / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T06:22:42Z (GMT). No. of bitstreams: 1 Ishizu_LarissaYuri_M.pdf: 1236160 bytes, checksum: d3b83c5f6882f0bbaa5b2be15aa753a0 (MD5) Previous issue date: 2012 / Resumo: Dados do Laboratório de Estudo do Estresse revelaram que a produção de lactato por adipócitos isolados de tecido adiposo visceral de humanos eutróficos e obesos mórbidos está sob estímulo de adrenoceptores ?1. Observou-se também hiperlactatemia no jejum de obesos mórbidos, aumento na liberação de lactato e na lipólise basal e estimulada em adipócitos viscerais isolados destes indivíduos, comparados com eutróficos. Porém dados de nosso laboratório e da literatura sugerem uma relação antagônica entre lipólise e lactatogênese, da qual participa o receptor GPR81, o qual está envolvido com lactato, inibindo a lipólise. Dados da literatura também sugerem a supressão da lipogênese e maior lipólise basal e estimulada dos adipócitos de obesos, com aumento da expressão da aquaporina 7, pelo qual o glicerol gerado na lipólise, é liberado. Por outro lado, estudos da literatura relatam a ocorrência da reesterificação dos produtos liberados após a lipólise de triacilgliceróis (TAGs) no tecido adiposo, na obesidade. Possivelmente, este seria o processo que promoveria a manutenção de grandes estoques de TAGs no tecido adiposo, apesar da maior lipólise e menor lipogênese. Frente aos nossos dados funcionais e os presentes na literatura sobre tecido adiposo visceral na obesidade, o objetivo deste estudo foi detectar alterações no metabolismo glicídico e lipídico neste tecido isolado de humanos obesos, em comparação com eutróficos, sob o enfoque da expressão gênica. Para tanto, quantificamos a expressão de genes envolvidos com a lactatogênese (lactato desidrogenase A, LDHA), lipogênese (acetil-CoA carboxilase, ACACA; glicerol quinase, GK; lipoproteína lipase, LPL) e lipólise (lipase hormônio sensível, LIPE; fosfodiesterase 3b, PDE3b; aquaporina 7, AQP7), e o gene relacionado com a inibição da lipólise via lactato (receptor-órfão acoplado à proteína G 81, GPR81) através do Real- Time PCR. Os resultados obtidos mostraram que o tecido adiposo de mulheres obesas expressa significativamente 49% a mais o gene LIPE e 66% a mais o gene LPL o de que mulheres eutróficas (p<0,05), enquanto que no tecido adiposo de homens não foi encontrada diferença significativa, apenas uma tendência a aumento do gene LPL nos obesos, comparados com eutróficos. Os adipócitos isolados do tecido adiposo visceral de homens obesos são morfometricamente maiores que os provenientes de eutróficos tendo como provável fator o aumento da expressão de LPL sem ser acompanhado de alterações na expressão de LIPE. Por outro lado, os adipócitos isolados do tecido adiposo visceral de mulheres obesas não apresentaram alterações morfométricas quando comparados aos adipócitos isolados de eutróficas, estes resultados são explicados pela análise da expressão dos genes LPL e LIPE do tecido adiposo desta região que se apresentou significativamente elevada em obesas. Desta forma, para este tecido estudado, existem alterações, dependente de gênero, que devem ser consideradas para estudos futuros sobre a obesidade. Neste trabalho, com as condições e a população estudada, referente a obesos e eutróficos de ambos os gêneros, podemos indicar as seguintes conclusões: a expressão de enzimas relacionadas à lipólise e a lipogênese em adipócitos isolados da região visceral de obesos é dependente do gênero enquanto que não há alterações significativas na expressão gênica relacionada à lactatogênese / Abstract: Previous data from the Laboratory of Stress Study showed that lactate production by adipocytes isolated from visceral adipose tissue of human normal and morbidly obese is under ?1-adrenoceptor stimulation. It was also observed hyperlactatemia in fasting from morbidly obese, an increase basal and stimulated lactate and glycerol production in visceral adipocytes isolated from these individuals, compared with normal weight. But data from our laboratory and the literature suggest an antagonistic relationship between lipolysis and lactatogênese, which participates in the GPR81 receptor, which is involved with lipolysis inhibition by lactate. Literature data also suggest the suppression of lipogenesis and increased basal and stimulated lipolysis in adipocytes of obese, with increased expression of aquaporin 7, whereby the glycerol generated in lipolysis, is released. Furthermore, published studies have reported the occurrence of re-esterification of the products released after lipolysis triacylglycerols (TAGs) in adipose tissue, in obesity. Possibly, this would be the process that would promote the maintenance of large stocks of TAGs in adipose tissue, despite the increased lipolysis and reduced lipogenesis. Front of our functional data and the literature on visceral adipose tissue in obesity, the aim of this study was to detect changes in glucose and lipid metabolism in this tissue isolated from obese humans, compared with normal weight, with a focus on gene expression. To this end, we quantified the expression of genes involved in lactatogênese (lactate dehydrogenase A LDHA), lipogenesis (acetyl- CoA carboxylase, ACACA, glycerol kinase, GK, lipoprotein lipase, LPL) and lipolysis (hormone sensitive lipase, LIPE; phosphodiesterase 3b , PDE3b; aquaporin 7 AQP7), and the gene related to the inhibition of lipolysis via lactate (orphan receptor-G protein coupled 81, GPR81) using Real-Time PCR. The results showed that adipose tissue isolated from obese women expressed significantly 49% more gene LIPE and 66% more LPL gene that women with normal weight (p <0.05), whereas in men no significant difference was found, only a tendency towards increased LPL gene in obese compared with normal weight. The isolated adipocytes visceral adipose tissue of obese men morphometrically are larger than those from normal weight bearing as the most probable cause increased expression of LPL without being accompanied by alterations in the expression of LIPE. Moreover, the isolated adipocytes visceral adipose tissue of obese women showed no morphological changes compared to normal weight of isolated adipocytes. These results are explained by analysis of gene expression of LPL and LIPE adipose tissue in this region which was significantly higher in obese women. Thus, there are changes, in this tissue studied, dependent on gender, which should be considered for future studies on obesity. In this work, the conditions and the population studied, referring to obese and normal for both genders, we can state the following conclusions: the expression of enzymes related to lipolysis and lipogenesis in adipocytes isolated from visceral fat of obese people is dependent on the gender while not there are significant changes in enzyme expression related to lactatogenesis / Mestrado / Fisiologia / Mestre em Biologia Funcional e Molecular

Plants have developed a number of ways how to minimise negative influence of the environment. As a consequence of stress action, plants carbohydrate metabolism is quite often influenced, esp. on the level of expression and activities of different enzymes and also several metabolites concentration. One of key enzymes of carbohydrate metabolism is invertase. The aim of this work was to find out, whether the activity of its isoforms (cytoplasmic, vacuolar and extracellular) in tobacco plants is influenced by Potato virus Y (PVY). It was shown, that activity of cytoplasmic invertase was not affected, but the activity of vacuolar and extracellular isoform was enhanced during potyviral infection. Hence, it is likely, that vacuolar and extracellular invertases are related to plant antiviral defence. The effect of PVY on other enzymes of carbohydrate metabolism and several metabolites content was studied. Activity of α-amylase and phosphorylase, starch-degrading enzymes, was strongly enhanced during potyviral infection. That is probably how plant cells get glucose, which is a key source of energy and metabolites for biosynthesis of different compounds. It may also serve as a signal molecule. Activity of other hydrolytic enzymes, β-glucosidase and β-hexosaminidase, was also slightly increased. There was no...

The current understanding of lactate metabolism in fish is based almost entirely on interpretation of concentration measurements that cannot be used to infer changes in flux. Moreover, the transporters regulating these fluxes have never been characterized in rainbow trout. My goals were: (1) to quantify lactate fluxes in rainbow trout under normoxic resting conditions, during acute hypoxia, and exercise by continuous infusion of [U-14C] lactate; (2) to determine lactate uptake capacity of trout tissues by infusing exogenous lactate in fish rest and during graded exercise, and (3) to clone monocarboxylate transporters (MCTs) and determine the effects of exhausting exercise on their expression. Such information could prove important to understand the mechanisms underlying the classic “lactate retention” seen in trout white muscle after intense exercise. In normoxic resting fish, the rates of appearance (Ra) and disappearance (Rd) of lactate were always matched (~18 to 13 µmol kg-1 min-1), thereby maintaining a low baseline blood lactate concentration (~0.8 mM). In hypoxic fish, Ra lactate increased from baseline to 36.5 µmol kg-1 min-1, and was accompanied by an unexpected 52% increase in Rd reaching 30.3 µmol kg-1 min-1, accounting for a rise in blood lactate to 8.9 mM. In exercising fish, lactate flux was stimulated > 2.4 body lengths per second (BL s-1). As the fish reached critical swimming speed (Ucrit), Ra lactate was more stimulated (+67% to 40.4 μmol kg-1 min-1) than Rd (+41% to 34.7 μmol kg-1 min-1), causing an increase in blood lactate to 5.1mM. Fish infused with exogenous lactate stimulated Rd lactate by 300% (14 to 56 μmol kg-1 min-1) during graded exercise, whereas the Rd in resting fish increased by only 90% (21 to 40 µmol kg-1 min-1). Four MCT isoforms were partially cloned and characterized in rainbow trout: MCT1b was the most abundant in heart, and red muscle, but poorly expressed in gill and brain where MCT1a and MCT2 were prevalent. MCT4 was more expressed in the heart. Transcript levels of MCT2 (+260%; brain), MCT1a (+90%; heart) and MCT1b (+50%; heart) were stimulated by exhausting exercise. This study shows that: (i) the increase in Rd lactate plays a strategic role in reducing the lactate load imposed on the circulation. Without this response, blood lactate accumulation would double; (ii) a high capacity for lactate disposal in rainbow trout tissues is elicited by the increased blood-to-tissue lactate gradient when extra lactate is administered; and (iii) rainbow trout may be unable to release large lactate loads rapidly from white muscle after exhausting exercise (lactate retention) because they poorly express MCT4 in white muscle and fail to upregulate its expression during exercise.

The current understanding of lactate metabolism in fish is based almost entirely on interpretation of concentration measurements that cannot be used to infer changes in flux. Moreover, the transporters regulating these fluxes have never been characterized in rainbow trout. My goals were: (1) to quantify lactate fluxes in rainbow trout under normoxic resting conditions, during acute hypoxia, and exercise by continuous infusion of [U-14C] lactate; (2) to determine lactate uptake capacity of trout tissues by infusing exogenous lactate in fish rest and during graded exercise, and (3) to clone monocarboxylate transporters (MCTs) and determine the effects of exhausting exercise on their expression. Such information could prove important to understand the mechanisms underlying the classic “lactate retention” seen in trout white muscle after intense exercise. In normoxic resting fish, the rates of appearance (Ra) and disappearance (Rd) of lactate were always matched (~18 to 13 µmol kg-1 min-1), thereby maintaining a low baseline blood lactate concentration (~0.8 mM). In hypoxic fish, Ra lactate increased from baseline to 36.5 µmol kg-1 min-1, and was accompanied by an unexpected 52% increase in Rd reaching 30.3 µmol kg-1 min-1, accounting for a rise in blood lactate to 8.9 mM. In exercising fish, lactate flux was stimulated > 2.4 body lengths per second (BL s-1). As the fish reached critical swimming speed (Ucrit), Ra lactate was more stimulated (+67% to 40.4 μmol kg-1 min-1) than Rd (+41% to 34.7 μmol kg-1 min-1), causing an increase in blood lactate to 5.1mM. Fish infused with exogenous lactate stimulated Rd lactate by 300% (14 to 56 μmol kg-1 min-1) during graded exercise, whereas the Rd in resting fish increased by only 90% (21 to 40 µmol kg-1 min-1). Four MCT isoforms were partially cloned and characterized in rainbow trout: MCT1b was the most abundant in heart, and red muscle, but poorly expressed in gill and brain where MCT1a and MCT2 were prevalent. MCT4 was more expressed in the heart. Transcript levels of MCT2 (+260%; brain), MCT1a (+90%; heart) and MCT1b (+50%; heart) were stimulated by exhausting exercise. This study shows that: (i) the increase in Rd lactate plays a strategic role in reducing the lactate load imposed on the circulation. Without this response, blood lactate accumulation would double; (ii) a high capacity for lactate disposal in rainbow trout tissues is elicited by the increased blood-to-tissue lactate gradient when extra lactate is administered; and (iii) rainbow trout may be unable to release large lactate loads rapidly from white muscle after exhausting exercise (lactate retention) because they poorly express MCT4 in white muscle and fail to upregulate its expression during exercise.

Ziel dieser vorliegenden, vergleichenden Literaturarbeit ist es, den heutigen Wissensstand in Bezug auf den Kohlenhydratstoffwechsel einer Frau darzustellen. Hierbei werden die physiologischen Veränderungen des Metabolismus zu verschiedenen Zeitpunkten im Leben einer Frau, begonnen mit der Kindheit und Pubertät, über Menstruation und Schwangerschaft bis hin zur Menopause, betrachtet und es werden die Ursachen und möglichen Mechanismen aufgezeigt, die zu Abweichungen der Insulinresistenz und der Insulinsekretion und damit möglicherweise zu einer Glukoseintoleranz bzw. einem Typ-2 Diabetes mellitus führen können. Der Kohlenhydratstoffwechsel wird nicht nur bezüglich der physiologischen, sondern auch in bezug auf die iatrogen verursachten Veränderungen, d.h. unter oraler hormonaler Kontrazeption, unter Hormonersatztherapie im Klimakterium, sowie hinsichtlich bestimmter Pathologien, wie dem zur Infertilität führenden polyzystischem Ovarsyndrom oder dem Gestationsdiabetes, untersucht. Ergebnis: Es scheint eine starke Verknüpfung zwischen dem weiblichen Reproduktionssystem und dem Kohlenhydratstoffwechsel zu geben, deren Interaktion von den unterschiedlichsten Faktoren beeinflusst wird. Der Frauenarzt sollte sich bei der Verschreibung hormoneller Kontrazeptiva, der Hormonersatztherapie und im Besonderen bei der Therapie des polyzystischen Ovarsyndroms sowie bei der Untersuchung seiner Patientinnen bewusst sein, dass verschiedene Lebensphasen, wie Pubertät, Schwangerschaft und Klimakterium und die damit verknüpften Veränderungen des Reproduktionssystems und der Sexualhormone auch deutliche metabolische Veränderungen nach sich ziehen können. Besonders eine erhöhte Insulinresistenz, die mit einer gesteigerten Insulinsekretion einhergeht, muss bedacht werden. Nicht nur das Syndrom X, eine Zusammenfassung von metabolischen Abnormitäten (Dyslipidämie, Insulinresistenz, Adipositas, Hypertonie), die mit einem deutlich erhöhten Risiko kardiovaskulärer Krankheiten und besonders der Atherosklerose einhergehen, sondern die daraus folgende steigende Prävalenz von Typ-2 Diabetes mellitus und das stark vermehrte Auftreten von Adipositas verlangen nach einer fachübergreifenden Zusammenarbeit zwischen Frauenärzten und Internisten. / The aim of this comparative review is to reveal the current standard of knowledge concerning carbohydrate metabolism in women. The study demonstrates the physiological changes in metabolism at various stages in a female life, from childhood and puberty, through menstruation and pregnancy and ending with the menopause, whilst also evaluating different causes and possible mechanisms that lead to aberrance in insulin resistance and insulin secretion and thereby potentially to glucose intolerance and/or type 2 Diabetes mellitus. In addition to presenting physiological alterations in glucose metabolism, this work also analyses changes generated by iatrogenic treatment such as oral contraceptives and hormone replacement therapy, as well as those caused by different pathologies like polycystic ovary syndrome or gestational diabetes. The results indicate a strong correlation between the female reproduction system and the carbohydrate metabolism. The interaction is influenced by the many very different factors. Before prescribing oral contraceptives, hormone replacement therapy in climacteric (especially during the treatment of infertility in PCOS), or examining patients, the gynaecologist needs to be aware of the fact that different phases in life along with sex steroids and connected changes in the reproductive system, might lead to severe metabolic diversifications. Special attention should be paid to an increased insulin resistance, associated with an augmentation in insulin secretion. Not only the metabolic syndrome, the simultaneous appearance of metabolic abnormalities (dyslipidaemia, insulin resistance, adiposity, hypertonia), which holds a higher risk of cardiovascular diseases, especially arteriosclerosis, but also the consequential increased prevalence of type 2 diabetes mellitus and the highly increased prevalence of adiposity, demand for a multidisciplinary collaboration between gynaecologists and internists.