Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Les prévalences de l'obésité et du diabète de type 2 sont en nette augmentation et ces deux pathologies sont étroitement liées. Le diabète de type 2 est caractérisé par une incapacité des cellules b du pancréas à sécréter de l'insuline et par un défaut de transport du glucose en réponse à l'insuline dans les tissus insulino-sensibles (ou insulino-résistance, IR) : le muscle squelettique, le cœur et le tissu adipeux. L'utilisation d'un traceur du transport du glucose marqué à l'iode radioactif, le 6DIG, permet d'évaluer l'IR de façon non-invasive dans le cœur et le muscle squelettique. L'objectif de ce travail était d'étudier le développement éventuel de l'IR chez des animaux rendus obèses par des régimes enrichis en lipides et/ou en glucides. Aucune IR n'a été mise en évidence au cours des trois mois d'expérience dans le modèle animal d'obésité induite par régime alimentaire. Des études visant à optimiser le traitement des données obtenues avec le 6DIG ont également été réalisées. Celles-ci nous ont permis de montrer : 1- une amélioration de la reproductibilité de la méthode de mesure de l'IR cardiaque par utilisation de l'analyse factorielle, 2- la faisabilité d'une diminution de la durée des acquisitions de la radioactivité pour la mesure de l'IR musculaire, 3- la nécessité de réaliser des prélèvements sanguins pour l'utilisation de la modélisation mathématique afin de traiter les données. / Prevalence of obesity and type 2 diabetes are in constant augmentation worldwide and these pathologies are closely associated. Type 2 diabetes represents a combination of pancreatic -cell dysfunction and insulin-regulated glucose uptake impairment in insulin-sensitive tissues: heart, skeletal muscles and adipose tissues. The novel tracer of glucose transport [123I]-6DIG allows the non invasive determination of insulin resistance (IR) in the heart and skeletal muscle. The aim of this study was to evaluate the development of IR in rats fed a high-fat and/or high-carbohydrate diets. No insulin resistance was observed during the 3 month of experimentation in our animal model. Study to optimize 6DIG obtained data reduction was also made. The results show: (1) improvement of the method data reduction reproducibility in the heart with factor analysis technique, (2) a possibility to reduce radioactivity acquisition time to muscle IR measurement, (3) the need of blood sample to use mathematical modeling in the data reduction.

Notre première étude épidémiologique s'est intéressée aux causes et facteurs de l'obésité juvénile au Liban. Elle montre que 17.1 % des adolescents Libanais sont en surpoids et 4.5% sont obèses. Les garçons sont plus en surpoids et obèses comparés aux filles (23% et 8.1% vs 12.7 et 1.8%). L'obésité, surtout chez les garçons, est associée à des habitudes sédentaires, à une déstructuration alimentaire et à un statut socioéconomique élevé. L'excès de masse grasse et les désordres métaboliques et hormonaux associés à l'obésité, surtout chez les adolescentes, aggravent le stress oxydant (SO). Ainsi, dans notre deuxième étude nous avons examiné l'effet de l'insulino‐résistance (IR) et de l'inflammation dans la survenue du SO au repos et en réponse à un exercice exhaustif chez les adolescentes en surpoids. Ces dernières présentent un SO plus élevé au repos (diminution du rapport GSH/GSSG, α‐tocophérol et GPx) et en réponse à un exercice exhaustif (augmentation F2‐Isop, ROOH, MPO) en comparaison aux adolescentes non obèses. Ce SO est corrélé à la composition corporelle et à l'IR et à l'inflammation basales. Toutefois, le paramètre déterminant du SO post‐exercice dans le groupe en surpoids était la surconsommation d'oxygène. L'entraînement aérobie est connu pour augmenter la résistance de l'organisme contre le SO induit par l'exercice chez le sujet sain. Notre dernier objectif, a été d'examiner l'effet de 3 mois d'entraînement aérobie multivarié sur le SO post‐exercice chez des adolescentes en surpoids. L'entraînement, en améliorant la composition corporelle chez les adolescentes en surpoids, a atténué la peroxidation lipidique et l'inflammation post‐exercice (F2‐IsoP, ROOH, LDLox, MPO) renforçant ainsi la tolérance de l'organisme vis‐à‐vis du SO induit par l'exercice

L'insulino-résistance est une caractéristique majeure du syndrome métabolique dont l'incidence ne cesse d'augmenter dans les pays industrialisés parallèlement à l'épidémie d'obésité. La résistance à l'insuline s'accompagne de diverses atteintes au niveau cardiaque, vasculaire et rénal. L'objectif principal était dans un modèle d'insulino-résistance induite par un excès de fructose chez le rat d'évaluer l'influence de la modulation en sodium (en excès ou en restriction) sur les changements métaboliques cardio-rénaux. D'une part, l'influence d'une restriction sodée concomitante à un régime riche en fructose a été évaluée. Nous avons montré que la restriction sodée prévenait les dommages cardio-rénaux. Ces effets bénéfiques ont été associés à une diminution de l'inflammation rénale et du stress oxydant. De plus, une prévention des modifications du tissu adipeux induites par le régime riche en fructose a été également observée. D'autre part l'impact d'une insulino-résistance en présence d'une consommation excessive et précoce (sevrage) en sodium a été évalué. Quand l'insulino-résistance (régime fructose) est initiée secondairement à un régime hypersodé, l'hypertrophie cardiaque associée au régime sodé est diminuée après l'ajout d'une insulino-résistance. Ce résultat paradoxal pourrait représenter une mal-adaptation du muscle cardiaque que confirme l'altération de la fonction systolique. En conclusion ce travail démontre une fois de plus l'impact de la nutrition dans la modulation des atteintes des organes cibles. L'importance d'adopter une nutrition raisonnée par contrôle de l'ingestion de sodium peut permettre de réduire les atteintes des organes cibles observées dans l'insulino-résistance. / Insulin resistance is a major feature of the metabolic syndrome whose incidence is increasing in industrialized countries, in parallel with the obesity epidemic. Insulin resistance is associated with various cardiac, vascular and renal damages. The main objective was to evaluate the influence of sodium modulation (excess or restriction) on cardio-renal changes in a model of insulin resistance induced by fructose in rats. On one hand, the influence of salt restriction concomitant with a high fructose diet was evaluated. We have shown that sodium restriction prevents cardio-renal damages. These beneficial effects were associated with a reduction in renal inflammation and oxidative stress. In addition, a prevention of adipose tissue changes induced by fructose-rich diet was also obeserved. On the other hand impact of insulin resistance in presence of an early (weaning) sodium and excessive consumption of sodium was evaluated. When insulin resistance (fructose diet) was initiated secondary to high salt diet, cardiac hypertrophy associated with sodium diet decreased after the addition of insulin resistance. This paradoxal result could represent a maladaptation of cardiac muscle confirmed the impaired systolic function. In conclusion this work further demonstrates the impact of nutrition in the modulation of target organ damage. Reducing sodium intake may provide an easy way to reduce target organ damage observed in insulino resistance.

Avaliou-se a velocidade da onda de pulso (VOP) carótido-femoral (CF) e carótido-radial (CR), por meio de técnica não-invasiva, em 14 indivíduos diabéticos do tipo 2 normotensos, A sensibilidade do barorreflexo (SBR) foi avaliada pela manobra de Valsalva e por testes com nitroglicerina e fenilefrina, durante monitorização não-invasiva batimento-a-batimento da pressão arterial. Os resultados foram comparados aos obtidos em 13 indívíduos saudáveis pareados por idade, índice de massa corporal e sexo. O grupo diabetes apresentou maiores níveis de glicose de jejum e HbA1c. As VOP CF e CR foram mais elevadas no grupo diabetes. A SBR estava reduzida nos diabéticos, nos testes com nitroglicerina, fenilefrina e, no reflexo de taquicardia da fase II da manobra de Valsalva. O aumento da VOP CF foi significativamente correlacionado à redução da SBR. Os resultados demonstram que em diabéticos do tipo 2 há maior rigidez arterial e a SBR está reduzida. A SBR é inversamente correlacionada ao aumento da rigidez arterial / Fourteen normotensive diabetic subjects were submitted to carotid-femoral (CF) and carotid-radial (CR) pulse wave velocity (PWV) analysis by non-invasive automatic device. The baroreflex sensitivity (BRS) was evaluated by Valsalva manoeuvre, phenylephrine and nitroglycerin tests during non-invasive beat-to-beat blood pressure monitoring. The data were compared with those obtained in 13 age, body mass index and sex-matched healthy subjects. The diabetes group showed a higher fasting glucose level and HbA1c. The CF PWV and CR PWV were higher in diabetic patients. The BRS was impaired in diabetic individuals in nitroglycerine and phenylephrine tests and, also, in the tachycardic reflex in phase II of Valsalva manoeuvre. The increase of CF PWV was significantly correlated to the decrease of BRS. The data demonstrated that, in diabetic normotensive individuals, arterial stiffness is increased and the BRS is impaired. The BRS is inverselly correlated to increase of aortic stiffness

CONTEXTO: as mulheres na pós-menopausa com diabetes mellitus não insulino-dependente (DMNID) constituem um grupo com maior risco de doença cardiovascular, visto serem muitas delas obesas, hipertensas e hiperlipidêmicas. A tibolona pode se constituir opção viável para a terapêutica de reposição hormonal nessas pacientes, no entanto são necessários estudos que avaliem as implicações clínicas, modificações metabólicas e resultados terapêuticos da tibolona nesse grupo de pacientes. OBJETIVO: determinar o perfil de segurança clínico-laboratorial da terapia com tibolona em pacientes na pós-menopausa portadoras de DMNID. TIPO DE ESTUDO: prospectivo, longitudinal, aberto e não controlado. LOCAL: Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto. PARTICIPANTES: 24 pacientes na pós-menopausa portadoras de DMNID, tratadas com 2,5 mg/dia de tibolona, pelo período de 6 meses. VARIÁVEIS: avaliação clínica, medidas antropométricas (IMC, RCQ e % Gordura), dosagens hormonais (FSH, LH, T4 livre, TSH), bioquímica sangüínea (uréia, creatinina, bilirrubinas, TGO, TGP, glicose e hemoglobina glicosilada) e ultra-sonografia transvaginal (espessura endometrial e volume uterino). ANÁLISE ESTATÍSTICA: teste não-paramétrico de Kolmogorov-Smirnov, análise de variância para medidas repetidas e teste “t" pareado para dois períodos, sendo adotado nível de significância de 5%. RESULTADOS: após 6 meses, todas as pacientes permaneceram em uso da medicação. Como efeitos colaterais, 8,3% apresentaram cefaléia, 8,3% mastalgia e 16,6% sangramento genital. Houve melhora na % de gordura corporal (43,15 ? 6,39 vs 41,76 ? 5,20; p=0,01) e na pressão arterial diastólica (87,29 ? 7,36 vs 78,33 ? 11,67; p=0,0005). Não houve variações significativas na pressão arterial sistólica, freqüência cardíaca, IMC e RCQ, bem como nos parâmetros bioquímicos. Houve diminuição dos sintomas climatéricos (22,17 ? 7,15 vs 3,08 ? 3,33; p=0,0001). A avaliação ultra-sonográfica não revelou variações do volume uterino e espessura endometrial. CONCLUSÃO: a utilização de tibolona durante um período de 6 meses, mostrou bom perfil de segurança clínico-laboratorial em pacientes na pós-menopausa portadoras de DMNID. / CONTEXT: Postmenopausal women with non-insulin-dependent diabetes mellitus (NIDDM) represent a high risk group since many of them are obese, hypertensive and hyperlipidemic, with a higher risk for cardiovascular disease. Tibolone may represent a viable option for the hormonal replacement therapy of these patients. There is the need for studies assessing the clinical implications, metabolic modifications and therapeutic results of tibolone in this group of patients. OBJECTIVE: To determine the clinical-laboratory safety profile of tibolone treatment in postmenopausal women with NIDDM over a period of 180 days. TYPE OF STUDY: Prospective, longitudinal, open and uncontrolled. PLACE: University Hospital, Faculty of Medicine of Ribeirão Preto. PARTICIPANTS: 24 postmenopausal women with NIDDM treated with 2.5 mg/day tibolone. VARIABLES: Clinical evaluation, anthropometric measurements (BMI, WHR and % body fat), blood determinations (FSH, LH, free T4, TSH, urea, creatinine, bilirubins, GOT and GPT, glucose, and glycosylated hemoglobin), and transvaginal ultrasonography (endometrial thickness and uterine volume). STATISTICAL ANALYSIS: Non-parametric Kolmogorov-Smirnov test, repeated measures analysis of variance and paired t-test for two periods, with the level of significance set at 5 %. RESULTS: After 6 months, all patients continued to use the medication. Side effects were headache in 8.3% of patients, mastalgia in 8.3%, and genital bleeding in 16.6%. There was an improvement in % body fat (43.15 ? 6.39 vs 41.76 ? 5.20; p=0.01) and diastolic arterial pressure (87.29 ? 7.36 vs 78.33 ? 11.67; p=0.0005). There were no significant variations in systolic arterial pressure, heart rate, BMI or WHR in the biochemical parameters. There was a reduction in the climacteric symptoms (22.17 ? 7.15 vs 3.08 ? 3.33; p=0.0001) and ultrasonography showed no changes in uterine volume or endometrial thickness. CONCLUSION: Treatment with tibolone for 180 days showed a good clinical-laboratory safety profile in postmenopausal women with NIDDM.

Este estudo, com delineamento tipo caso-controle, teve como proposta testar as hipóteses de que a amamentação ao seio é um fator de proteção para o DMID e o leite de vaca, introduzido precocemente na alimentação infantil, é um fator de risco para a doença. Os casos foram identificados na Associação de Diabetes Juvenil de São Paulo e no ambulatório de Endocrinologia da Escola Paulista de Medicina. Trezentos e quarenta e seis casos, com idade inferior a 18 anos no momento da entrevista, foram comparados com 346 controles pareados aos casos segundo sexo, idade e local de residência. Foram consideradas como variáveis de principal interesse a duração do aleitamento exclusivamente ao seio, a idade da introdução de alimentos lácteos na dieta e ter recebido leite em pó na maternidade. Foram consideradas como variáveis de controle as idades da mãe e do pai no momento do nascimento da criança, o histórico da mãe de rubéola congênita, a duração da gestação, o peso e o comprimento ao nascer, a situação de vacinação, os antecedentes relativos a doenças viróticas da criança, o histórico da criança de episódios graves de diarréia, a data da insulinoterapia, os antecedentes familiares de DMID e DMNID, a renda familiar per capita e a ordem de nascimento da criança. Utilizaram-se o teste t de Student pareado para a comparação das médias das variáveis cujos valores têm distribuição normal e o teste pareado dos sinais dos postos de Wilcoxon para as demais, a técnica de tábua de vida atuarial para se conhecer, aos 7 e aos 60 dias, a proporção de crianças ainda em aleitamento exclusivamente ao seio e sem introdução de alimentos lác- teos. O modelo de regressão logística condicional foi utilizado tanto para as análises da gradação dos odds ratios como para ajustar os efeitos sobre o DMID das três variáveis de interesse a possíveis variáveis de confusão. Os resultados encontrados neste estudo indicam que são fatores de risco para o DMID a ausência de aleitamento exclusivamente, especialmente durante a primeira semana de vida (OR = 2,13, IC: 1,28 - 3,55) e a idade da introdução de alimentos lácteos, especialmente quando esses alimentos são introduzidos durante os primeiros sete dias de vida (OR = 2,29; IC: 1,37 - 3,83). / This case-control study aimed to test the assumption that breast feeding protects against insulin-dependent diabetes mellitus, and that the early introduction of cow milk into the infant diet is a risk factor for the disease. The cases were identified in the Juvenile Diabetes Association of São Paulo, and in the Out-patients Endocrinology Department of the Escola Paulista de Medicina. Three hundred and forty-six cases among patients younger than eighteen years old at the time of the interview were compared with 346 paired control cases for sex, age and place of residence. The main variables were the duration of exclusive breast feeding , the age at which milk products were introduced into the diet, and whether powdered milk was given in the maternity unit. The ages of the parents when the child was born, history of congenital rubella in the mother, duration of gestation, weight and height at birth, vaccination status, the child\'s viral disease history, the child\'s history of severa attacks of diarrhea, the date of insulin therapy, previous familial history of insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus, the per-capita income of the family, and the order of birth of the child. Student\'s paired test was used to compare the mean values of variables with normal distribution, and Wilcoxon\'s signed ranks test was used for all other variables. The actuarial life table technique was used at 7 and 60 days in order to determine the proportion of children still being exclusively breast fed without the introduction of milk products. The conditional logistical regression method was used in dose-response analyses of the odds ratio and to adjust for the effect of the three variables of interest and possible confounding variables on insulin-dependent diabetes mellitus. The findings of this study indicate that the lack of exclusive breast feeding is a risk factor to insulin-dependent diabetes mellitus, particularly during the first week of life (OR=2.13; IC: 1.28-3.55) and that the age at introduction of milk products is a risk factor for the disease, particularly when these products are introduced during the first seven days of life (OR=2.29; IC: 1.37 -33.83).

Les exosomes sont des nanovésicules de 30 à 100nm sécrétées dans le milieuextracellulaire par une grande majorité de types cellulaires. Entourés d’une bicouchelipidique similaire aux radeaux lipidiques, ils contiennent des protéines, de l’ARNm et desmicroARNs. Récemment, il a été montré que les exosomes pourraient participer auxdialogues moléculaires inter-organes, au même titre que les protéines solubles (hormones etcytokines). Au cours de cette thèse, nous avons émis l’hypothèse que le muscle squelettiquepourrait utiliser les exosomes comme mode de communication intercellulaire, en plus desmyokines qu’il sécrète. Nous avons montré en couplant des techniques de microscopieélectronique, de génomique, de biologie cellulaire et moléculaire, et d’analysesprotéomiques, que le muscle était capable de sécréter des exosomes, dont la compositionvariait au cours de la myogenèse. De plus, nous avons montré que les exosomes sécrétéspar les cellules prolifératrices et différenciées avaient des rôles distincts au cours de ladifférenciation myogénique, via le transfert des microARNs notamment.En parallèle, nous nous sommes intéressés aux exosomes sécrétés par le musclesquelettique en situation d’insulino-résistance induite par du palmitate. En utilisant unedouble approche in vitro et in vivo, nous avons montrés que les exosomes sécrétés par lacellule musculaire insulino-résistante ont une morphologie et une composition luminalemodifiée. Enfin, ces exosomes sécrétés sembleraient transmettre un signal délétère àd’autres cellules musculaires différenciées, et aux autres tissus insulino-sensibles, comme lepancréas. / Exosomes are nanovesicles from 30 to 100nm, secreted into the extracellular spaceby a large majority of cell types. Surrounded by a lipid bilayer similar to lipid rafts, theycontain proteins, mRNA and microRNAs. Recently, it has been shown that exosomes maybe involved in inter-organs dialogues, as well as soluble proteins (hormones and cytokines).In this thesis, we hypothesized that skeletal muscle could use exosomes asintercellular communication mode, in addition to myokines. We have shown by couplingelectron microscopy techniques, genomics, molecular and cellular biology, and proteomicanalyzes, that the muscle was able to secrete exosomes, whose composition varied duringmyogenesis. In addition, we have shown that exosomes secreted by proliferating anddifferentiated cells have distinct roles during the myogenic differentiation, especially throughthe transfer of microRNAs. In parallel, we are interested in exosomes secreted by insulin resistant skeletalmuscle, induced by palmitate. Using a dual approach in vitro and in vivo, we have shown thatexosomes secreted by insulin-resistant muscle cells have a morphology and a luminalcomposition modified. Finally, these exosomes secreted seem to transmit a deleterioussignal to other differentiated muscle cells, and other insulin-sensitive tissues such as thepancreas.

O objetivo desse estudo foi investigar a associação da inflamação com a resistência periférica à insulina (RI) na vigência de dietas obesogênicas, suplementação com óleo de peixe (SOP) e ausência de TLR-4. Os animais receberam dieta balanceada (DB), DB e leite condensado (DB+LC), hiperlipídica (HFD) ou HFD+LC. DB+LC e HFD levaram ao aumento: no ganho de massa corpórea (MC) e expressão de F4/80 e leptina no tecido adiposo (TA) em relação à DB. Em relação à HFD, HFD+LC provocou: aumento no HOMA-IR (4x), nos conteúdos de IL-6, IL-10, TNF-a, IL-1b, ICAM-1, VCAM-1 e leptina no TA. Comparada à DB+LC, HF+LC aumentou: a MC, HOMA-IR e expressão de F4/80 e reduziu a expressão de leptina no TA. A SOP nos animais em DB reduziu a expressão de F4/80, TNF-a e TLR-4 no fígado. A SOP em HFD reduziu o MC, HOMA-IR e aumentou o conteúdo de adiponectina no TA. A deleção de TLR-4 elevou o MC em DB+OP e a gordura mesentérica no HFD+OP. Assim, o consumo elevado de gordura ou açúcar causou obesidade e a associação de ambos potencializou a obesidade e induziu RI e inflamação no TA. A suplementação com OP atenuou a inflamação associada à DB e a obesidade e RI na vigência de HFD, sendo esses efeitos dependentes de TLR-4. / The aim of this study was to investigate the association between inflammation and insulin resistance (IR) under obesogenic diets, fish oil supplementation (FOS) and TLR-4-/-. The mice were fed a balanced diet (BD), BD and condensed milk (BD+CM), high-fat diet (HFD) or high-fat diet and condensed milk (HFD+CM). The BD+CM and HFD increased: body weight gain (BWG), F4/80 and leptin in adipose tissue (AT). The HFD+CM compared to HFD increased: HOMA-IR, the contents of IL-6, IL-10, TNF-a, IL-1b, ICAM-1, VCAM-1 and leptin in AT. As compared to BD+CM, HFD+CM increased: BWG, HOMA-IR, F4/80 and reduced the leptin in AT. The FOS+BD reduced F4/80, TNF-a and TLR-4 in the liver. The FOS+HFD reduced BWG, HOMA-IR and increased the adiponectin in AT. TLR-4 deletion increased BWG in the FOS+BD and mesenteric fat in the FOS+HFD groups. The high consumption of fat or sugar induced obesity and the association of both potentiated this effect leading to IR and inflammation in adipose tissue and perivascular fat. FO supplementation attenuated the inflammation when associated with BD and the obesity and IR induced by HFD in a TLR-4 dependent-manner.