Hoje a criação de avestruz ((Struthio camelus, Linnaeus 1758)) é uma atividade de grande potencial, porém não existem padrões definidos sobre a histologia do seu fígado, que é um órgão de grande importância no metabolismo, o conhecimento de sua histologia e anatomia pode contribuir para a detecção de doenças e deficiências nutricionais que influenciam no crescimento e desenvolvimento do animal. Os objetivos desta pesquisa são: Estudar a anatomia e histologia do fígado e a ramificação de sua artéria hepática, veia porta hepática e ducto biliar. Para a realização da parte macroscópica foram utilizados quinze avestruzes com idades entre 12 e 18 meses (com peso médio em torno de 80 a 100 kg), provenientes do abatedouro Don Pig, situado próximo à cidade de Botucatu no estado de São Paulo. Os animais foram abatidos com pistola pneumática e posteriormente submetidos a sangria. Foram injetadas com látex a artéria hepática, o ducto biliar e a veia porta. O fígado dos avestruzes apresentam dois lobos (direito e esquerdo). No caso o direito é maior que o esquerdo e ambos são subdivididos em dorsal, intermédio e ventral. Além disso, amostras do fígado foram processadas para a observação em microscopia de luz e microscopia eletrônica de transmissão (MET). A hematoxilina e eosina (H.E), picrossírius, Gordon e Sweets, Sudan black e o ácido peródico de Schiff (PAS) são colorações usadas respectivamente para observar a morfologia do fígado, colágeno, fibras reticulares, gordura e glicogênio. Foram encontrados os espaços porta- hepáticos (artéria hepática, veia porta e ducto biliar e as veias centrolobulares). O glicogênio presente mostrou a média de 5,68%. O conteúdo lipídico, conferiu um aspecto goticular compatível com um quadro de esteatose hepática e a média obtida foi de 9,83%. Foi encontrado colágeno ao redor dos espaços porta-hepáticos, artérias centrolobulares e capilares sinusóides e a média foi de 14,71%. Encontrou-se também fibras reticulares ao redor dos capilares sinusóides e a média foi de 5,96%. Quanto à MET notou-se que no citoplasma dos hepatócitos desses animais existem numerosas mitocôndrias, glicogênio, muitas gotas de gordura, alguns lisossomos, retículo endoplasmático granular ao redor das mitocôndrias, algumas células estreladas, eritrócitos, núcleo, célula em degeneração e o canalículo biliar ao centro. Provavelmente o quadro sugestivo de esteatose é resultante do estado nutricional dos animais, já que nenhum outro aspecto relevante foi encontrado. Como estas aves são destinadas ao abate, sua alimentação é formulada para que os animais apresentem rápido desenvolvimento e alto ganho de peso, provavelmente com níveis de lipídios acima do necessário, causando uma deposição de micelas de gordura nos hepatócitos. Estes resultados demontraram que os hepatócitos dos avestruzes são muito simulares as outras aves apesar de também serem muito similares na estrutura das células do fígado de mamíferos. / At present the ostrich (Struthio camelus) breeding has been showing a great economical potential, although yet there are not distinct patterns about the histology of its liver, which is an organ of key importance in terms of metabolism. The knowledge of its histology and anatomy can help the detection of diseases and nutritional deficiencies that affect the growth and development of this bird. The aims of this work are to study the liver anatomical and histological structure and the branching of the hepatic artery, hepatic portal vein and bile duct. In the macroscopic study 15 ostriches with an average age of 12-18 months and average weight of 80-100 Kg, proceeding from Don Pig Abatteur, located next to Botucatu, São Paulo, were used. The birds were slaughtered with air gun and subsequently submitted to bleeding. The hepatic artery, the bile duct and the hepatic portal vein were injected with latex. The ostrich liver presents two lobules (right and left), being the right one larger than the left and both are subdivided into dorsal, intermediate and ventral. Liver samples were processed for light and electron transmission microscopic studies. Hematoxilin and eosin (HE), picrosirius, Gordon and Sweets, Sudan black and Schiff periodic acid (PAS) were respectively used to observe the liver morphology, collagen, reticular fibers, lipids and glycogen. The liver portal spaces were determined (hepatic artery, portal vein, bile duct and centrolobular veins). An average of 5.68% of glycogen was observed. The lipidic content provided a droplet aspect compatible to hepatic esteatosis, with an average of 9.83%. Collagen fibers around the liver portal spaces, centrolobular arteries and sinusoidal cappilaries were detected, at an average of 14.71%, as well as reticular fibers located in the vicinity of sinusoidal capillaries with an average of 5.96%. Through transmission electron microscopy we noticed in the hepaticyte cytoplasm the presence of numerous mithocondria, glycogen, several lipidic droplets, some lysosomes, granular endoplasmatic reticulum around the mithocondria, some stellate cells, erythrocytes, nucleus and degenerating cells, besides the central biliary canaliculus. The suggestive steatotic results might result from the animals nutritional status, once no other relevant aspect was detected. The birds are slaughtered for food comsumption and their ration is balanced striving for faster growth and higher weight gains, which are achieved through extra lipidic levels, motivating deposition of lipidic micelles in the hepatocytes. Our results demonstrated that ostrich and other birds hepatocytes are very similar.

Peroxisome proliferator-activated receptor alpha (PPARa) and delta (PPARd) belong to the nuclear receptor superfamily. PPARa is a target of lipid-lowering drugs and PPARd promotes fatty acid utilization and is a promising anti-diabetic drug target. However, evidence is growing that PPARd-agonism can stimulate fat accumulation in liver, which may aggravate the toxic situation in diabetics. The aim of the study was to characterise the hepatic transcriptional and lipid response of humanized mouse models to PPARd-agonists. In our studies of mice conditionally-expressing human PPARd (hPPARd), or the dominant-negative derivative of hPPARd (hPPARd?AF2) or wild-type animals, we demonstrated that GW501516, a potent PPARd activator, promoted up-regulation of the genes involved in lipid turnover, stimulated significant weight loss and promoted hepatic steatosis in these mouse models. There was time-dependent accumulation of hepatic triglycerides observed in wild-type and in conditionally-expressing hPPARd mice fed a diet containing PPARd synthetic ligand. This was not seen in animals conditionally-expressing hPPARd?AF2, neither in PPARa-KO or PPARd-KO animals. Concurrently, activation of PPARd in humanised animals caused significant depletion, as compared with controls, of adipose tissue deposits when fed normal or high fat diet. This effect was completely absent in PPARa-KO or PPARd-KO mice, fed diet containing GW501516. Genome-wide transcriptional profiling of GW501516 effects in the livers of these different mouse strains was performed. In PPARa-KO mice fed PPARd-agonist, some direct PPARd target genes were still up-regulated, demonstrating that they are not sufficient for the observed phenotype. In addition the blood HDL-raising effects of GW501516 were preserved in the PPARa-KO mice. This suggests a novel finding that both PPARd and PPARa receptors are essential for GW501516-driven weight loss and hepatic steatosis, with PPARa working downstream of PPARd.

A Doença Hepática Gordurosa Não Alcoólica (DHGNA) é uma condição clínicopatológica comum, caracterizada por depósito de lipídeos no hepatócito do parênquima hepático. A esteatose hepática (EH) é um dos componentes da DHGNA e caracteriza-se pela presença de vacúolos de lipídeos, principalmente triacilgliceróis (triglicerídeos), dentro dos hepatócitos. Alterações na oxidação das gorduras no fígado ou redução na exportação de lipoproteínas de muito baixa densidade (VLDL) a partir do órgão são os principais mecanismos etiopatogênicos envolvidos com a EH. A patogênese da DHGNA é multifatorial e diversos fatores ou condições têm sido relacionados à predisposição para o seu desenvolvimento. Atualmente, diferentes tratamentos farmacológicos para DHGNA estão sendo propostos, mas ainda não há nenhum estudo comprobatório da sua eficácia. Objetiva-se avaliar os efeitos da suplementação da colina e do frutooligossacarídeo (FOS) na dieta de ratos Wistar, no modelo de esteatose hepática, induzido por dieta hiperglicídica. Foram utilizados 46 ratos machos, da raça Wistar adultos com peso variando entre 250 - 320 g, vindos do Biotério Central do Campus da USP Ribeirão Preto. Do lote inicial de animais foram distribuídos de forma aleatória nos diferentes grupos de estudo de I a IV, dependendo da indução ou não da esteatose. Considerou-se fase I o período correspondente a indução de esteatose e fase II quando se submeteu os animais a suplementação com nutrientes (Grupos III e IV), ou quando os animais receberam dieta padrão pós fase I (Grupo II) . Os animais do Grupo I (controle) receberam ração padrão do biotério que foi igual para todos os animais, sendo separado um lote da mesma ração para todo o experimento. Foi analisado as seguintes variáveis: Ingestão alimentar semanal, evolução do peso dos animais, nitrogênio urinário, amônia urinária, colesterol total e triacilgliceróis séricos, peso úmido de fígado e coração, nitrogênio e gordura tecidual, dosagem de vitamina E, malondialdeído (MDA) e glutationa no tecido hepático e análise histopatológica. Observamos que nenhum dos nutrientes empregados (colina e FOS) foi eficaz na redução da quantidade de gordura do fígado pela análise histológica. Nenhum dos nutrientes adicionados foi capaz de proteger o fígado da ação dos radicais livres, já que o MDA, um marcador indireto da geração do estresse oxidativo, manteve-se com valores elevados mesmo na fase de tratamento. Ocorreu diminuição dos níveis de triacilgliceróis em todos os grupos submetidos à indução de esteatose, do início ao final do experimento. O frutooligossacarídeo foi capaz de reduzir os níveis de colesterol sérico, em relação aos seus níveis basais, quando suplementado após indução de esteatose. / Non-alcoholic fatty liver disease (NAFLD) is a common clinical pathological condition characterized by fat accumulation in the the hepatic parenchyma hepatocyte. Liver steatosis (HS) is one of the components of NAFLD and is characterized by the presence of lipids vacuoles, mainly triacylglycerol, within the hepatocites. Alterations in fat oxidation in the liver or very low density proteins lipoproteins tranport from the organ are the main etiopatogenic mechanisms involved in HS. NAFLD patogeny is multifactor, thus several factors have been associated the propensity to develop it. Presently, many drug treatments for NAFLD are being suggested, however, there have been no studies that prove their efficacy so far. The aim of this study was to assess the effects of choline and fructooligosaccharide (FOS) suplementation in Wistar rats with HS induced by high glicid diet. Forty six adult male Wistar rats weighing between 250g and 320g from the USP (Ribeirão Preto-USP) central vivarium were used. They were divided randomly into different study groups from I to IV depending on whether steatosis would be induced or not. Phase I of the study was the period corresponding to steatosis induction and phase II was when the animals received nutrient suplementation (Groups III and IV) or when they received standard diet (Group II). Group I animals (control) received the usual vivarium food, which was the same for all of them. A certain amount of that same food was kept aside for the duration of the experiment. The following variables were analyzed: weekly food intake, weight gain, urine ammonia, urine nitrogen, total cholesterol and serum triacylglycerol, liver and heart humid weight, nitrogen and tissue fat, vitamin E, malondialdehyde (MDA) and glutathione content in the liver tissue and hitopathological analysis. As observed, neither of the nutrients (choline and FOS) was efficient in reducing the amount of fat in the liver. Neither of the nutrients added was able to protec the liver from free radicals, once the MDA, a indirect marker for oxidative stress generation, showed high levels even during the treatment phase. There was a reduction in triacylglycerol levels in all steatosis induced groups, from the beginning to the end of the experiment. Fructooligosaccharide was able to reduce the levels of serum cholesterol, in relation to its basal levels, when suplemented after steatosis induction.

abstract: The prevalence of obesity and obesity-related disorders have increased world-wide. In the last decade, the intestinal microbiome has become a major indicator of metabolic and gastrointestinal health. Previous research has shown that high-fat diet (HFD) consumption can alter the microbial composition of the gut by increasing the abundance of gram-positive bacteria associated with the onset of obesity and type 2 diabetes. Although, the most common form of obesity and metabolic syndrome intervention is exercise and diet, these recommendations may not improve severe cases of obesity. Thus, an important relevance of my project was to investigate whether the intake of an organometallic complex (OMC) would prevent the onset of metabolic and gastrointestinal complications associated with high-fat diet intake. I hypothesized that the consumption of a HFD for 6 weeks would promote the development of metabolic and gastrointestinal disease risk factors. Next, it was hypothesized that OMC treatment would decrease metabolic risk factors by improving insulin sensitivity and decreasing weight gain. Finally, I hypothesized that HFD-intake would increase the abundance of gram-positive bacteria associated with gastrointestinal disease. My preliminary data investigated the effects of a 6-week HFD on the development of hepatic steatosis, intestinal permeability and inflammation in male Sprague Dawley rats. I found that a 6-week HFD increases hepatic triglyceride concentrations, plasma endotoxins and promotes the production of pro-inflammatory cytokines in the cecum wall. I then investigated whether OMC treatment could prevent metabolic risk factors in male Sprague-Dawley rats fed a HFD for 10 weeks and found that OMC can mitigate risk factors such hyperglycemia, liver disease, impaired endothelial function, and inflammation. Lastly, I investigated the effects of a 10-week HFD on the gastrointestinal system and found an increase in liver triglycerides and free glycerol and alterations of the distal gut microbiome. My results support the hypothesis that a HFD can promote metabolic risk factors, alter the gut microbiome and increase systemic inflammation and that OMC treatment may help mitigate some of these effects. Together, these studies are among the first to demonstrate the effects of a soil-derived compound on metabolic complications. Additionally, these conclusions also provide an essential basis for future gastrointestinal and microbiome studies of OMC treatment. / Dissertation/Thesis / Doctoral Dissertation Biology 2019

Alcoholic liver disease (ALD) is one of the most common liver diseases worldwide characterized by the accumulation of lipids within the liver, inflammation and the possibility of progressing to cirrhosis and liver failure. More importantly, there are currently no effective treatments for ALD and liver transplantation remains the only therapeutic option for end-stage liver disease. Previous studies have shown that ALD is a result of a combination of endoplasmic reticulum (ER) stress, lipid metabolism dysregulation and inflammation. It has been previously reported that alcohol disrupts gut microbiota homeostasis and causes increased endotoxins that contribute to the pathology of ALD. However, the detailed mechanism(s) underlying ALD and disease progression is poorly understood. We have discovered that sphingosine kinase 2 (SphK2) deficient (SphK2-/-) mice on an alcohol diet exhibit increased steatosis and inflammation compared to wild type mice. Sphingosine 1-phosphate receptor 2 (S1PR2) and SphK2 have been previously shown to play a key role in nutrient metabolism and signaling. However, their roles in alcohol-induced liver injury have not been characterized. The overall objective of this study is to determine the molecular mechanism(s) by which disruption of S1PR2-mediated SphK2 signaling contributes to ALD. The effects of alcohol on mouse primary hepatocytes and cultured RAW264.7 macrophages were examined. The acute on chronic alcohol mouse model from NIAAA that recapitulates the drinking pattern of human ALD patients was used to study the effects of SphK2 deficiency in ALD. In addition, 60-day chronic alcohol mouse model was used to determine whether a more severe form of ALD was present in SphK2-/- mice. The results indicated that SphK2-/- mice on an alcohol diet exhibited an increased amount of hepatic steatosis compared to wild type mice. Genes regulating lipid metabolism were also dysregulated in SphK2-/- mice. SphK2-/- mice also had increased inflammation and liver injury as shown by an upregulation of inflammatory markers and increased levels of liver enzymes. Moreover, SphK2 protein expression levels were downregulated in the human livers of alcoholic cirrhotic and hepatocellular carcinoma (HCC) patients. These findings contribute to a greater understanding of the pathophysiology of ALD and could provide information on the development of novel therapeutics against ALD.

Apoptosis is a genetically regulated form of cell death that occurs when the cell is exposed to physiological, pathogenic, or cytotoxic stimuli. Unregulated apoptosis (too much or too little apoptosis) at any time from embryogenesis to adulthood, can result in a variety of disease states, such as neurodegenerative disorders, autoimmunity, cardiovascular disease, liver and kidney problems, and cancer. A reasonable estimation is that either too little or too much cell death contributes to half of the main medical illnesses for which adequate therapy or prevention is lacking. The apoptotic pathways can be initiated by reactive oxygen species (ROS) and inflammatory molecules, both of which are believed to be up-regulated in a state of obesity. In addition, multiple studies have shown that the risk of developing cardiovascular disease, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and certain types of cancers increase with increasing degree of obesity in both men and women. Despite the well characterized association of obesity and disease incidence, the mechanisms by which obesity contributes to disease pathology are poorly understood. Previously, in our research group, it was shown that obese Zucker rats, which are the animal model of human obesity, are more prone to colon cancer and hepatic steatosis compare to their relative lean counterparts. Therefore, applying Real-Time RT-PCR, the expression levels of some pro- and anti-apoptotic members of the BCL-2 family of genes were investigated to figure out the possible effect of obesity on apoptotic gene expression levels. Also, apoptotic gene expression patterns of obese and lean Zucker rats after DNA damage induction were compared to each other in order to find the possible connection of apoptotic gene expression with disease progression in obese individuals. This is the first study comparing the expression level of BCL-2 family of genes in obese versus lean liver and colon tissue. In this study, it was shown that an obese genotype affects pro- and anti-apoptotic gene expression levels and patterns whether or not DNA damage has been induced in both liver and colon. The results show a clear alteration in apoptotic gene expression levels in obese individuals compared to their lean counterparts leading to the proposal that apoptosis may be involved in the obesity related colon cancer and liver steatosis.

The overall objective of this research was to investigate the status of tumor necrosis factor-α (TNF-α), and molecules associated with its signaling, in the pathological state of hepatic steatosis. The effect of NSAID piroxicam, a cancer preventive agent also known to affect TNF-α signaling on hepatic steatosis, was also investigated. The biological state of the tissue was assessed by examining the expression of TNF-α signaling molecule in whole tissue, as well as in hepatic lipid raft. Lipid rafts are dynamic assemblies of cholesterol and sphingolipids, microdomains that form in the exoplasmic leaflet of the biological membranes shown to play a role in compartmentalization, modulation and integration of the cell signaling. In the present research, Zucker obese rats were used as a model of human obesity and insulin resistant state. These rats exhibit hepatic steatosis in adulthood similar to those noted in obese individuals. Female Zucker obese and lean rats (5 weeks old) were fed a semisynthetic diet with or without piroxicam (150 ppm). Zucker lean counterparts served as control. After 8 weeks of feeding, rats were euthanized and liver from each animal was collected. Liver tissue from each animal was processed for histology and biochemical analysis which included lipids and proteins (COX-1 and 2, TNF-α, TNF-RI and RII, IKK-β, IκB-α and NF-κB). Liver histology and the level of total lipids confirmed that Zucker obese rats had hepatic steatosis, which was further augmented by piroxicam treatment. Whole tissue protein expression, using western blot, showed that the steatotic liver differed from non-steatotic livers by having lower levels of TNF-RII. TNF-RII showed a trend which was inversely proportional to the pathological state of the tissue. The obese-piroxicam liver had the lowest level of TNF-RII and lean livers had the highest (p<0.05). The total NF-κB level was higher in the obese and obese-piroxicam groups compared to the lean or lean-piroxicam groups (p<0.05). Piroxicam treatment lowered the level of NF-κB in obese and lean livers. IκB-α was higher in obese livers than in lean livers. The nuclear level of NF-κB by western blot analysis showed the same pattern as noted in the whole tissue homogenate. However, the difference in the level between obese and lean was marked. The obese nuclei contained two to three fold higher levels of NF-κB protein than the lean liver nuclei. IκB-α level was significantly higher in the obese liver tissues and nuclei than their lean counterparts. While transcriptionally active NF-κB was higher (p<0.05) in the obese livers than in the lean livers, the difference between obese and lean groups was not as significant as that noted for the level of NF-κB assessed by western blot. This suggests that the proportion of active NF-κB present in the nuclear fraction is much higher in the lean than in the obese nuclei. Lipid raft was extracted and identified successfully from obese and lean livers. The total caveolin and flotillin levels were significantly higher in the liver lipid rafts of the obese-piroxicam than that of the other groups. This is the group that also exhibited higher steatosis. Piroxicam treatment significantly decreased the level of caveolin in the lean liver and significantly increased the level of flotillin in the obese liver. While COX-1 was not detectable, however, the level of COX-2 and TNF-RII in lipid raft was opposite to the level noted in the whole tissue homogenate. TNFRII was highest in the obese-piroxicam lipid raft and lowest in the lean-piroxicam lipid raft. TNF-RII, COX-2, IκB-α and NF-κB proteins were the molecules profoundly affected by the pathological state of the tissue and piroxicam treatment. This research is the first to report the presence of IκB-α in the nuclear compartment with a higher level in the nuclei and whole tissue in the obese liver than in the lean liver. This research demonstrates that TNF-α to NF-κB axis is altered in steatotic liver, and analysis of lipid rafts in steatotic and non-steatotic liver demonstrates that lipid rafts play a distinct role in modifying the biological availability of key proteins in the pathological state of liver steatosis.

Apoptosis is a genetically regulated form of cell death that occurs when the cell is exposed to physiological, pathogenic, or cytotoxic stimuli. Unregulated apoptosis (too much or too little apoptosis) at any time from embryogenesis to adulthood, can result in a variety of disease states, such as neurodegenerative disorders, autoimmunity, cardiovascular disease, liver and kidney problems, and cancer. A reasonable estimation is that either too little or too much cell death contributes to half of the main medical illnesses for which adequate therapy or prevention is lacking. The apoptotic pathways can be initiated by reactive oxygen species (ROS) and inflammatory molecules, both of which are believed to be up-regulated in a state of obesity. In addition, multiple studies have shown that the risk of developing cardiovascular disease, type 2 diabetes mellitus, nonalcoholic fatty liver disease, and certain types of cancers increase with increasing degree of obesity in both men and women. Despite the well characterized association of obesity and disease incidence, the mechanisms by which obesity contributes to disease pathology are poorly understood. Previously, in our research group, it was shown that obese Zucker rats, which are the animal model of human obesity, are more prone to colon cancer and hepatic steatosis compare to their relative lean counterparts. Therefore, applying Real-Time RT-PCR, the expression levels of some pro- and anti-apoptotic members of the BCL-2 family of genes were investigated to figure out the possible effect of obesity on apoptotic gene expression levels. Also, apoptotic gene expression patterns of obese and lean Zucker rats after DNA damage induction were compared to each other in order to find the possible connection of apoptotic gene expression with disease progression in obese individuals. This is the first study comparing the expression level of BCL-2 family of genes in obese versus lean liver and colon tissue. In this study, it was shown that an obese genotype affects pro- and anti-apoptotic gene expression levels and patterns whether or not DNA damage has been induced in both liver and colon. The results show a clear alteration in apoptotic gene expression levels in obese individuals compared to their lean counterparts leading to the proposal that apoptosis may be involved in the obesity related colon cancer and liver steatosis.

Background. Estimates are that one third of children will develop type 2 diabetes in their lifetime. Lifestyle changes, including physical activity are established effective tools to prevent and manage type 2 diabetes in adults but the evidence in youth is lacking. Several key questions remain including: (1) Can youth with type 2 diabetes achieve target glycemic control with lifestyle changes alone? (2) Is type 2 diabetes in youth associated with low physical activity and cardiorespiratory fitness? and (3) What is the appropriate intensity of physical activity to reduce the risk for type 2 diabetes in overweight youth? Methods. Three studies were conducted to answer these questions: i) a retrospective chart review to determine the clinical efficacy of lifestyle monotherapy to manage glycemia in youth newly diagnosed with type 2 diabetes; ii) a cross sectional study to test the association between physical activity, cardiorespiratory fitness and type 2 diabetes risk factors in youth; and iii) a randomized controlled trial of physical activity designed to determine the training intensity required to improve insulin resistance and reduce intrahepatic lipid content in overweight youth at risk for type 2 diabetes (interim results presented). Results. Study A. Over 50% of youth newly diagnosed with type 2 diabetes and glycosylated hemoglobin ≤9% were able to achieve target glycemic control for as long as 12 months with lifestyle monotherapy. Study B. Physical activity levels (4905±2075 vs. 6937±2521 vs. 8908±2949 steps/day, p<0.05 vs. healthy weight youth) and cardiorespiratory fitness (23.4±5.9 vs. 26.7±6.0 vs. 36±6.6 ml/kg/min, ii p<0.05) are lower in youth with type 2 diabetes versus overweight and healthy weight controls. Intrahepatic lipid is significantly higher (13.0%±14.1 vs. 5.6%±6.2 vs. 1.4%±1.4, p<0.05) and inversely associated with insulin sensitivity (r = -0.40, p<0.001). Study C. Interim analyses present promising trends from a 6-month physical activity intervention. Conclusions. Lifestyle therapy can be an effective tool to manage new-onset diabetes in certain youth, and is also important in the prevention of type 2 diabetes in youth. Youth with type 2 diabetes are characterized by low levels of physical activity and cardiorespiratory fitness. Interim results are presented from a randomized controlled physical activity trial that we anticipate at completion will provide promising data to guide development of community-based programming to reduce risk for type 2 diabetes in overweight youth.

Background. Estimates are that one third of children will develop type 2 diabetes in their lifetime. Lifestyle changes, including physical activity are established effective tools to prevent and manage type 2 diabetes in adults but the evidence in youth is lacking. Several key questions remain including: (1) Can youth with type 2 diabetes achieve target glycemic control with lifestyle changes alone? (2) Is type 2 diabetes in youth associated with low physical activity and cardiorespiratory fitness? and (3) What is the appropriate intensity of physical activity to reduce the risk for type 2 diabetes in overweight youth? Methods. Three studies were conducted to answer these questions: i) a retrospective chart review to determine the clinical efficacy of lifestyle monotherapy to manage glycemia in youth newly diagnosed with type 2 diabetes; ii) a cross sectional study to test the association between physical activity, cardiorespiratory fitness and type 2 diabetes risk factors in youth; and iii) a randomized controlled trial of physical activity designed to determine the training intensity required to improve insulin resistance and reduce intrahepatic lipid content in overweight youth at risk for type 2 diabetes (interim results presented). Results. Study A. Over 50% of youth newly diagnosed with type 2 diabetes and glycosylated hemoglobin ≤9% were able to achieve target glycemic control for as long as 12 months with lifestyle monotherapy. Study B. Physical activity levels (4905±2075 vs. 6937±2521 vs. 8908±2949 steps/day, p<0.05 vs. healthy weight youth) and cardiorespiratory fitness (23.4±5.9 vs. 26.7±6.0 vs. 36±6.6 ml/kg/min, ii p<0.05) are lower in youth with type 2 diabetes versus overweight and healthy weight controls. Intrahepatic lipid is significantly higher (13.0%±14.1 vs. 5.6%±6.2 vs. 1.4%±1.4, p<0.05) and inversely associated with insulin sensitivity (r = -0.40, p<0.001). Study C. Interim analyses present promising trends from a 6-month physical activity intervention. Conclusions. Lifestyle therapy can be an effective tool to manage new-onset diabetes in certain youth, and is also important in the prevention of type 2 diabetes in youth. Youth with type 2 diabetes are characterized by low levels of physical activity and cardiorespiratory fitness. Interim results are presented from a randomized controlled physical activity trial that we anticipate at completion will provide promising data to guide development of community-based programming to reduce risk for type 2 diabetes in overweight youth.