Additionally, cyclosporin A, an inhibitor of the mitochondrial permeability transition (MPT) pore, failed to prevent hIAPP-induced DeltaPsim collapse, cytochrome c and AIF release and caspase-3 activation, indicating that the MPT pore was not involved in hIAPP-induced apoptosis. On the other hand, potential crosstalk between the extrinsic and intrinsic apoptotic pathways was demonstrated by cleavage of Bid by caspase-8 in the apoptotic process triggered by hIAPP. / It is widely accepted that human islet amyloid polypeptide (hIAPP) aggregation plays an important role in the loss of insulin-producing pancreatic beta cells. Insulin secretion impairment and cell apoptosis can be due to mitochondrial dysfunction in pancreatic beta cells. hIAPP-induced cytotoxicity is mediated by the generation of reactive oxygen species (ROS). Phycocyanin (PC) is a natural compound from blue-green algae that is widely used as food supplement. Currently, little information is available about the effect of hIAPP on mitochondrial function of beta cells and protection of PC against hIAPP-induced cytotoxicity. In this thesis, I hypothesize that hIAPP may impair beta cell function with the involvement of mitochrondrial dysfunction, and this effects could be attenuated by PC. Therefore, the aim of this study was to investigate the role of mitochondria in hIAPP-induced apoptosis, the in vitro protective effects of PC and explore the underlying mechanisms. / It was found that hIAPP induced apoptosis in INS-1E cells with the disruption of mitochondrial function, as evidenced by ATP depletion, mitochondrial mass reduction, mitochondrial fragmentation and loss of mitochondrial membrane potential (DeltaPsim). Further molecular analysis showed that hIAPP induced changes in the expression of Bcl-2 family members, release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria into cytosol, activation of caspases and cleavage of poly (ADP-ribose) polymerase. Interestingly, the hIAPP-induced mitochondrial dysfunction in INS1-E cells was effectively restored by co-treatment with PC. / Our results showed that hIAPP inhibited the INS-1E cell growth in a dose-dependent manner. However, cytotoxicity of hIAPP was significantly attenuated by co-incubation of the cells with PC. hIAPP induced DNA fragmentation and chromatin condensation, which were key characteristics of cell apoptosis. These changes were inhibited by PC as examined by TUNEL assay and DAPI staining. Moreover, PC significantly prevented the hIAPP-induced overproduction of intracellular ROS and malonaldehyde (MDA), as well as changes of activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzymes. Furthermore, hIAPP triggered the activation of mitogen-activated protein kinases (MAPKs) such as c-Jun N-terminal kinase (JNK) and p38 kinase, and these effects were effectively suppressed by PC. / Taken together, I have demonstrated for the first time the involvement of mitochondrial dysfunction in hIAPP-induced INS-1E cell apoptosis, which was attenuated by PC through attenuating oxidative stress, modulating JNK and p38 pathways and reducing mitochondrial dysfunction. / Li, Xiaoling. / Adviser: Juliana Chung Ngor Chan. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 150-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

O diabete melito é uma doença metabólica com alta prevalência na população e quando no estado descompensado pode causar diversas complicações metabólicas e clínicas, entre elas a osteoporose. Entretanto, ainda não foram completamente esclarecidos os mecanismos pelos quais o diabete diminui a densidade mineral óssea e aumenta o risco a fraturas. Recentemente foram descritos alguns genes que estão envolvidos no turnover ósseo: OPG, RANK e RANKL. Além disso, o uso de hipoglicemiantes orais como as tiazolidinedionas (TZD), pode influenciar negativamente o metabolismo ósseo. Com a finalidade de identificar marcadores sensíveis de alteração do metabolismo ósseo foram investigadas as relações entre a expressão dos genes OPG, RANK e RANKL em células do sangue periférico e a resposta a TZDs em pacientes com DM2. Foram selecionados 52 indivíduos (36 diabéticos e 16 normoglicêmicos), no Instituto Dante Pazzanese de Cardiologia. Os indivíduos diabéticos foram tratados com pioglitazona (15, 30 e 45 mg/ dia/ via oral) por 16 semanas. Foram colhidas amostras de sangue, antes e após o tratamento para determinação de exames laboratoriais e extração de RNA total. A expressão de mRNA dos genes OPG, RANK e RANKL foi quantificada e avaliada por RT-PCR em tempo real, empregando-se o GAPD como controle endógeno. Observou-se que nos pacientes DM2 após o tratamento com pioglitazona, houve diminuição da glicemia de jejum, glicemia pós-prandial, insulina, Hb1Ac, índices HOMA-IR e HOMA-β e aumento nas concentrações séricas de HDL, demonstrando a eficácia do tratamento. Ao comparar a expressão dos genes entre o grupo DM2 (sem tratamento) e o grupo normoglicêmico (NG), foi evidenciado um aumento da expressão de OPG no grupo NG em relação ao grupo DM2, e ao analisar a expressão entre as mulheres, constatou-se aumento da expressão de RANK no grupo DM2 em relação ao grupo NG. Além disso, ao correlacionar a expressão dos genes com as dosagens dos parâmetros bioquímicos, constatou-se que o aumento da expressão de RANK e RANKL está relacionado com o aumento das concentrações de cálcio ionizado e diminuição da expressão de OPG. Esses dados sugerem que a atividade osteoclástica está aumentada nos pacientes DM2 e com o tratamento o quadro osteoporótico pode ser agravado. / The diabetes mellitus is a metabolic disease with high prevalence in the population and can cause various metabolic and clinic complications, including osteoporosis, when it is decompensated. However, the mechanisms by which diabetes decreases bone mineral density and increases the risk of fractures are not completely clarified. Recently some genes which are involved in bone turnover were described: OPG, RANK and RANKL. Moreover, the treatment using oral hypoglycemic drugs such as thiazolidinediones (TZD), may negatively affect the bone metabolism. In order to identify sensitive markers related to the bone metabolism, were investigated the relationship between the expression of genes OPG, RANK and RANKL in peripheral blood leukocytes and the response to TZDs treatment in patients with DM2. Fifty-two individuals were selected (36 diabetics and 16 normoglycemics) at Dante Pazzanese Institute of Cardiology. Diabetic patients were treated with pioglitazone (15, 30 and 45 mg I day I oral) during 16 weeks. Blood samples were collected for biochemical analyses and total RNA extraction, before and after treatment. Gene expression of the genes OPG, RANK and RANKL in peripheral blood mononuclear cells was evaluated by Real Time PCR, using the GAPD housekeeping gene as the endogenous reference. In DM2 patients after treatment with pioglitazone there was reduction in their fasting glycemia, postprandial glycemia, insulin, Hb1Ac, HOMA-IR and HOMA-β indices, and their serum concentrations of HDL increased, which demonstrates the effectiveness of the treatment. The bone profile markers have not altered after treatment, suggesting an anabolic action of the insulin in bone metabolism of these patients. Normoglycemics (NG) group gene expression, when compared with DM2 group (with no treatment), had increased OPG expression. Besides, RANK expression in group DM2 was higher than NG group when it was analyzed among women. Furthermore, having correlated the expression of the genes with the biochemical parameters data, the increase on RANK and RANKL gene expression is related to increased concentrations of ionized calcium and to decreased expression of OPG gene. These results are suggestive that osteoclastic activity is higher in DM2 patients, the treatment can exacerbate osteoporosis severity and the bone markers does not have enough sensibility to differentiate changes in individuals with type 2 diabetes mellitus.

Thesis (M.A. (Psychology)) -- University of Limpopo, 2000 / Refer to document

Intermittent fasting (IF) is a recently popularized meal timing strategy whereby individuals abstain continuously from any energy intake for 16 to 20 hours each day, subsequently condensing energy intake into a short period spanning 4 to 8 hours. We aimed to test the effects of intermittent fasting in 10 individuals with Type 2 Diabetes Mellitus in conjunction with recommendations to consume a high protein diet in a 6 to 8 week withdrawal study. This study consisted of three phases: baseline, intervention, and follow-up. During the 2-week baseline and intervention phases participants consumed meals at regular times. Biochemical, anthropometric, and physical activity measurements were taken at the end of each phase. Participants reported morning, afternoon and evening self-monitored blood glucose and fasting duration on a daily basis, in addition to completing a remote food photography diary three times within each study phase. Despite the short duration of the intervention phase, intermittent fasting led to significant decreases in weight, BMI, morning SMBG, and overall reductions in waist circumference, C-reactive protein, energy intake, carbohydrate intake, and fat intake. There were significant variations between participants in response to intermittent fasting in respect to changes in lipids and insulin sensitivity, which could not be explained by baseline biochemical or anthropometric measures, fasting duration, energy intake, or physical activity. Upon cessation of intermittent fasting, biochemical changes regressed towards baseline values during the follow-up period. Intermittent fasting was well tolerated by most participants, and no severe adverse events were noted. Morning nausea was the most common complaint, which abruptly ceased when medication timing was changed.

By the year 2025, it is anticipated that over 300 million individuals world wide will have type 2 diabetes, with a projected increase from 84 to 288 million (170%) in developing countries and from 51 to 72 million (42%) in developed countries. Diabetes leads to a markedly increased risk of heart disease and renal failure and to expensive and debilitating retinopathy and neuropathy. Cognitive decline is also increased. As there is accumulating evidence of the beneficial effects of moderate carbohydrate, low fat dietary patterns compared to high carbohydrate diets, this thesis will focus on the effects of moderate carbohydrate high protein dietary patterns (total carbohydrate: protein: fat ratio of 40%:34%:26%) on glycemic control, risk factors for macrovascular disease and cognitive function. Information on two key areas in type 2 diabetes will be presented, 1. Acute effects of dietary patterns, moderately carbohydrate restricted and high in protein on glucose levels assessed using continuous glucose monitoring systems (CGMS) with verification of these results through a small repeat study. 2. Chronic effects of energy restricted dietary patterns, moderately carbohydrate restricted and high in protein on glucose levels, HbA1c, cognitive function, cardiovascular disease (CVD) risk markers and renal function. In the acute study, we recruited 23 subjects with type 2 diabetes. The participants were randomized to each of 4, 3-day interventions in a cross over design with a 4 day wash out period in which the carbohydrates were distributed differently at each meal; carbohydrates evenly distributed across the day, or carbohydrates loaded at breakfast, lunch or dinner. Glucose levels were continuously measured using CGMS. Outcomes were assessed by postprandial peak glucose (Gmax), time spent above 12 mmol/L (T>12) and total area under the glucose curve (AUC20). The intervention showed that an even distribution of carbohydrates did not optimise blood glucose control, whereas carbohydrates loaded at the lunch time meal provided the most favourable postprandial profile. To verify these results we conducted a repeat study. Six of the previous participants accepted the invitation to return and complete the even distribution arm of the study after a 20 week time lag. The intervention showed that although HbA1c, fasting blood glucose (FBG), AUC, exercise and ambient temperature remained constant there was a significant effect of change in sunlight hours on Gmax, suggesting an effect of sunlight. To assess the chronic effects of energy restricted dietary patterns on the determinants of HbA1c, cognitive function, CVD risk markers and renal function under conditions of weight loss, we recruited 82 participants with type 2 diabetes. These participants were randomised to one of two high protein energy restricted dietary patterns that differed in cholesterol content, for a 12 week period, in a parallel design. A sub group of these participants completed cognitive function testing with (n=34) or without (n=17) CGMS at baseline and at 8 weeks. After 8 weeks of the intervention the determinants of HbA1c under conditions of energy restriction were evaluated. The intervention showed the change in FBG accounted for most of the variance in change in HbA1c, but % energy reduction also contributed independently of FBG. Both energy restricted high protein diets equally improved glycemic control, particularly T>12, AUC, HbA1c and FBG. Fifty one participants completed cognitive testing to evaluate the effect of weight loss and blood glucose control on cognition. Cognitive function was not altered by time, diet, baseline lipid levels. Working memory was predicted by FBG. Short term memory was predicted by FBG, Gmax and AUC24. Sixty five participants completed 12 weeks of the intervention to assess CVD risk markers and renal function. Renal function was maintained and CV markers improved on both dietary patterns, with greatest improvement in HDL-C observed in the group consuming a high protein, energy restricted dietary pattern, high in dietary cholesterol. In conclusion, in the context of a high protein, carbohydrate restricted dietary pattern, cognitive function and renal function did not change, while glycemia and CV risk profiles improved with weight loss over the short term. Under conditions of energy balance diurnal glucose profiles were optimal when the carbohydrates were loaded in the lunch meal. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342253 / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2008

By the year 2025, it is anticipated that over 300 million individuals world wide will have type 2 diabetes, with a projected increase from 84 to 288 million (170%) in developing countries and from 51 to 72 million (42%) in developed countries. Diabetes leads to a markedly increased risk of heart disease and renal failure and to expensive and debilitating retinopathy and neuropathy. Cognitive decline is also increased. As there is accumulating evidence of the beneficial effects of moderate carbohydrate, low fat dietary patterns compared to high carbohydrate diets, this thesis will focus on the effects of moderate carbohydrate high protein dietary patterns (total carbohydrate: protein: fat ratio of 40%:34%:26%) on glycemic control, risk factors for macrovascular disease and cognitive function. Information on two key areas in type 2 diabetes will be presented, 1. Acute effects of dietary patterns, moderately carbohydrate restricted and high in protein on glucose levels assessed using continuous glucose monitoring systems (CGMS) with verification of these results through a small repeat study. 2. Chronic effects of energy restricted dietary patterns, moderately carbohydrate restricted and high in protein on glucose levels, HbA1c, cognitive function, cardiovascular disease (CVD) risk markers and renal function. In the acute study, we recruited 23 subjects with type 2 diabetes. The participants were randomized to each of 4, 3-day interventions in a cross over design with a 4 day wash out period in which the carbohydrates were distributed differently at each meal; carbohydrates evenly distributed across the day, or carbohydrates loaded at breakfast, lunch or dinner. Glucose levels were continuously measured using CGMS. Outcomes were assessed by postprandial peak glucose (Gmax), time spent above 12 mmol/L (T>12) and total area under the glucose curve (AUC20). The intervention showed that an even distribution of carbohydrates did not optimise blood glucose control, whereas carbohydrates loaded at the lunch time meal provided the most favourable postprandial profile. To verify these results we conducted a repeat study. Six of the previous participants accepted the invitation to return and complete the even distribution arm of the study after a 20 week time lag. The intervention showed that although HbA1c, fasting blood glucose (FBG), AUC, exercise and ambient temperature remained constant there was a significant effect of change in sunlight hours on Gmax, suggesting an effect of sunlight. To assess the chronic effects of energy restricted dietary patterns on the determinants of HbA1c, cognitive function, CVD risk markers and renal function under conditions of weight loss, we recruited 82 participants with type 2 diabetes. These participants were randomised to one of two high protein energy restricted dietary patterns that differed in cholesterol content, for a 12 week period, in a parallel design. A sub group of these participants completed cognitive function testing with (n=34) or without (n=17) CGMS at baseline and at 8 weeks. After 8 weeks of the intervention the determinants of HbA1c under conditions of energy restriction were evaluated. The intervention showed the change in FBG accounted for most of the variance in change in HbA1c, but % energy reduction also contributed independently of FBG. Both energy restricted high protein diets equally improved glycemic control, particularly T>12, AUC, HbA1c and FBG. Fifty one participants completed cognitive testing to evaluate the effect of weight loss and blood glucose control on cognition. Cognitive function was not altered by time, diet, baseline lipid levels. Working memory was predicted by FBG. Short term memory was predicted by FBG, Gmax and AUC24. Sixty five participants completed 12 weeks of the intervention to assess CVD risk markers and renal function. Renal function was maintained and CV markers improved on both dietary patterns, with greatest improvement in HDL-C observed in the group consuming a high protein, energy restricted dietary pattern, high in dietary cholesterol. In conclusion, in the context of a high protein, carbohydrate restricted dietary pattern, cognitive function and renal function did not change, while glycemia and CV risk profiles improved with weight loss over the short term. Under conditions of energy balance diurnal glucose profiles were optimal when the carbohydrates were loaded in the lunch meal. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1342253 / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2008

Diss. (sammanfattning) Linköping : Univ., 2002. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Texas Health Science Center at Houston, School of Public Health, 2008. / "May 2008." Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0912. Adviser: Deanna M. Hoelscher. Includes bibliographical references (leaves 139-149).

O diabete melito é uma doença metabólica com alta prevalência na população e quando no estado descompensado pode causar diversas complicações metabólicas e clínicas, entre elas a osteoporose. Entretanto, ainda não foram completamente esclarecidos os mecanismos pelos quais o diabete diminui a densidade mineral óssea e aumenta o risco a fraturas. Recentemente foram descritos alguns genes que estão envolvidos no turnover ósseo: OPG, RANK e RANKL. Além disso, o uso de hipoglicemiantes orais como as tiazolidinedionas (TZD), pode influenciar negativamente o metabolismo ósseo. Com a finalidade de identificar marcadores sensíveis de alteração do metabolismo ósseo foram investigadas as relações entre a expressão dos genes OPG, RANK e RANKL em células do sangue periférico e a resposta a TZDs em pacientes com DM2. Foram selecionados 52 indivíduos (36 diabéticos e 16 normoglicêmicos), no Instituto Dante Pazzanese de Cardiologia. Os indivíduos diabéticos foram tratados com pioglitazona (15, 30 e 45 mg/ dia/ via oral) por 16 semanas. Foram colhidas amostras de sangue, antes e após o tratamento para determinação de exames laboratoriais e extração de RNA total. A expressão de mRNA dos genes OPG, RANK e RANKL foi quantificada e avaliada por RT-PCR em tempo real, empregando-se o GAPD como controle endógeno. Observou-se que nos pacientes DM2 após o tratamento com pioglitazona, houve diminuição da glicemia de jejum, glicemia pós-prandial, insulina, Hb1Ac, índices HOMA-IR e HOMA-β e aumento nas concentrações séricas de HDL, demonstrando a eficácia do tratamento. Ao comparar a expressão dos genes entre o grupo DM2 (sem tratamento) e o grupo normoglicêmico (NG), foi evidenciado um aumento da expressão de OPG no grupo NG em relação ao grupo DM2, e ao analisar a expressão entre as mulheres, constatou-se aumento da expressão de RANK no grupo DM2 em relação ao grupo NG. Além disso, ao correlacionar a expressão dos genes com as dosagens dos parâmetros bioquímicos, constatou-se que o aumento da expressão de RANK e RANKL está relacionado com o aumento das concentrações de cálcio ionizado e diminuição da expressão de OPG. Esses dados sugerem que a atividade osteoclástica está aumentada nos pacientes DM2 e com o tratamento o quadro osteoporótico pode ser agravado. / The diabetes mellitus is a metabolic disease with high prevalence in the population and can cause various metabolic and clinic complications, including osteoporosis, when it is decompensated. However, the mechanisms by which diabetes decreases bone mineral density and increases the risk of fractures are not completely clarified. Recently some genes which are involved in bone turnover were described: OPG, RANK and RANKL. Moreover, the treatment using oral hypoglycemic drugs such as thiazolidinediones (TZD), may negatively affect the bone metabolism. In order to identify sensitive markers related to the bone metabolism, were investigated the relationship between the expression of genes OPG, RANK and RANKL in peripheral blood leukocytes and the response to TZDs treatment in patients with DM2. Fifty-two individuals were selected (36 diabetics and 16 normoglycemics) at Dante Pazzanese Institute of Cardiology. Diabetic patients were treated with pioglitazone (15, 30 and 45 mg I day I oral) during 16 weeks. Blood samples were collected for biochemical analyses and total RNA extraction, before and after treatment. Gene expression of the genes OPG, RANK and RANKL in peripheral blood mononuclear cells was evaluated by Real Time PCR, using the GAPD housekeeping gene as the endogenous reference. In DM2 patients after treatment with pioglitazone there was reduction in their fasting glycemia, postprandial glycemia, insulin, Hb1Ac, HOMA-IR and HOMA-β indices, and their serum concentrations of HDL increased, which demonstrates the effectiveness of the treatment. The bone profile markers have not altered after treatment, suggesting an anabolic action of the insulin in bone metabolism of these patients. Normoglycemics (NG) group gene expression, when compared with DM2 group (with no treatment), had increased OPG expression. Besides, RANK expression in group DM2 was higher than NG group when it was analyzed among women. Furthermore, having correlated the expression of the genes with the biochemical parameters data, the increase on RANK and RANKL gene expression is related to increased concentrations of ionized calcium and to decreased expression of OPG gene. These results are suggestive that osteoclastic activity is higher in DM2 patients, the treatment can exacerbate osteoporosis severity and the bone markers does not have enough sensibility to differentiate changes in individuals with type 2 diabetes mellitus.

Indiana University-Purdue University Indianapolis (IUPUI) / Glucose homeostasis is maintained through the coordinated actions of insulin secretion from pancreatic beta cells and insulin action in peripheral tissues. Dysfunction of insulin action yields insulin resistance, and when coupled with altered insulin secretion, results in type 2 diabetes (T2D). Exocytosis of intracellular vesicles, such as insulin granules and glucose transporter (GLUT4) vesicles is carried out by similar SNARE (soluble NSF attachment receptor) protein isoforms and Munc18 proteins. An additional regulatory protein, Doc2b, was implicated in the regulation of these particular exocytosis events in clonal cell lines, but relevance of Doc2b in the maintenance of whole body glucose homeostasis in vivo remained unknown. The objective of my doctoral work was to delineate the mechanisms underlying regulation of insulin secretion and glucose uptake by Doc2b in effort to identify new therapeutic targets within these processes for the prevention and/or treatment of T2D. Towards this, mice deficient in Doc2b (Doc2b-/- knockout mice) were assessed for in vivo alterations in glucose homeostasis. Doc2b knockout mice were highly susceptible to preclinical T2D, exhibiting significant whole-body glucose intolerance related to insulin secretion insufficiency as well as peripheral insulin resistance. These phenotypic defects were accounted for by defects in assembly of SNARE complexes. Having determined that Doc2b was required in the control over whole body glycemia in vivo, whether Doc2b is also limiting for these mechanisms in vivo was examined. To study this, novel Doc2b transgenic (Tg) mice were engineered to express ~3 fold more Doc2b exclusively in pancreas, skeletal muscle and fat tissues. Compared to normal littermate mice, Doc2b Tg mice had improved glucose tolerance, related to concurrent enhancements in insulin mumsecretion from beta cells and insulin-stimulated glucose uptake in the skeletal muscle. At the molecular level, Doc2b overexpression promoted SNARE complex assembly, increasing exocytotic capacities in both cellular processes. These results unveiled the concept that intentional elevation of Doc2b could provide a means of mitigating two primary aberrations underlying T2D development.