Cardiovascular disease secondary to atherosclerosis is the most common cause of human morbidity and mortality. An early and fundamental event in the development of atherosclerosis is abnormal vascular endothelial and smooth muscle function. This can be measured by flow mediated dilatation and glyceryl trinitrate mediated dilatation in children at risk of atherosclerosis. Folic acid improves endothelial function (flow mediated dilatation) in adults with coronary artery disease. No studies have previously investigated the effects of folic acid on vascular function in at risk children with diabetes or obesity. In a cross sectional study an evaluation of vascular endothelial and smooth muscle function and their determinants was performed in 159 children with type 1 diabetes, 58 children with obesity, and 53 healthy children. Children with type 1 diabetes and children with mild to moderate obesity had comparable and severe vascular dysfunction but different determinants. Vascular function in healthy and obese children related to both body mass index and weight (adjusted for age and sex), and blood glucose. Children with obesity had lower folate levels and higher homocysteine levels than children with type 1 diabetes, an abnormal lipid profile and raised inflammatory markers. A randomised double blind placebo controlled cross over trial of 8 weeks of folic acid supplementation was performed in 38 children with type 1 diabetes. In these children, folic acid improved endothelial function with a sustained increase in folate levels but independent of homocysteine levels. Folic acid did not improve smooth muscle function. A randomised double blind placebo controlled parallel trial of 8 weeks folic acid supplementation was performed including 53 obese children. Folic acid did not improve vascular function in obese children in spite of sustained increase in folate levels, and a decrease in homocysteine levels. It was concluded that children with type 1 diabetes and obesity have comparable and severe endothelial and smooth muscle function. Determinants of vascular function in children, including weight and glucose, represent a continuum effect. Folic acid supplementation improved endothelial function in children with type 1 diabetes but not in children with obesity, whose metabolic changes causing endothelial dysfunction differ from children with diabetes. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1317003 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

Polycystic ovary syndrome (PCOS) is a complex clinical condition characterized by hyperandrogenism and chronic oligo/anovulation. Infrequent ovulation and metabolic alterations in women with PCOS are associated with subfertility and probably increased miscarriage rates compared with normal fertile women. The overall risk of developing type 2 diabetes and impaired glucose tolerance (IGT) is three- to sevenfold higher in PCOS women, and the onset of glucose intolerance seems to occur at an earlier age than in healthy controls. Women with PCOS also have several risk factors for cardiovascular disease, although it is unclear whether they actually experience more cardiovascular events than other women. Very few studies assessing the long-term reproductive and metabolic consequences in older women with previously confirmed PCOS have been conducted. In this long-term follow-up of women with PCOS, 84 women with a diagnosis of PCOS between 1987 and 1995 and age at the follow-up > 35 years and an age-matched population-based group of control women participated. Data on reproductive outcome, ovarian reserve, endothelial function, insulin sensitivity and beta-cell function were collected. According to our results most women with PCOS had given birth and the rate of spontaneous pregnancies was relatively high. The rate of miscarriages was not increased in PCOS patients and the ultrasound findings together with increased levels of anti-müllerian hormone suggested that their ovarian reserve is superior to women of similar age. PCOS women displayed signs of endothelial dysfunction, but this was largely due to the increased prevalence of independent risk factors for cardiovascular disease such as increased BMI, triglycerides and blood pressures. IGT and type 2 diabetes occurred more often in PCOS women. Free androgen levels and beta-cell function decreased over time whereas insulin sensitivity remained unchanged. Obesity at young age and progressive weight-gain rendered them more prone to be insulin resistant at the follow-up. Beta-cell function was increased in PCOS women in comparison with control subjects but declined over time. Independent of PCOS phenotype at the index assessment and persistence of PCOS symptoms at the follow-up investigation, premenopausal women with PCOS had lower insulin sensitivity and increased beta cell function in comparison with control subjects. Conclusion: The long-term reproductive outcomes of PCOS are similar compared to women with normal ovaries. Although symptoms and androgen levels are normalized over time, women with PCOS continue to display reduced insulin sensitivity and increased beta-cell function and they also have an increased risk of IGT and type 2 diabetes.

Σκοπός: Να διερευνηθεί η επίδραση της καθημερινής χορήγησης σιλδεναφίλης στα επίπεδα διαλυτών δεικτών της ενδοθηλιακής λειτουργίας σε άνδρες με στυτική δυσλειτουργία. Μέθοδοι: Ασθενείς πάνω από 18 ετών με στυτική δυσλειτουργία αγγειακής αιτιολογίας για πάνω από 6 μήνες, είτε μόνη είτε σε συνδυασμό με νοσολογικές καταστάσεις ισχυρά συσχετιζόμενες με ενδοθηλιακή δυσλειτουργία όπως σακχαρώδης διαβήτης/μεταβολικό σύνδρομο, υπέρταση και στεφανιαία νόσος, έλαβαν σιλδεναφίλη 25 mg ημερησίως από του στόματος για 4 εβδομάδες. Δείκτες της ενδοθηλιακής λειτουργίας μετρήθηκαν στο πλάσμα στην αρχή και το τέλος της θεραπείας χρησιμοποιώντας τυπικές μεθόδους και εμπορικά διαθέσιμα υλικά. Αποτελέσματα: 112 άνδρες με μέση ηλικία (SD) 60,6 (7,3) έτη ολοκλήρωσαν το θεραπευτικό πρωτόκολλο. Η χορήγηση 25 mg σιλδεναφίλης καθημερινά για 4 εβδομάδες μείωσε σημαντικά τα επίπεδα της ενδοθηλίνης-1 σε σύγκριση με την αρχή της θεραπείας (2,83 ± 1,63 έναντι 3,24 ± 1,90 pg/ml, p<0,001). Σημαντικές αλλαγές παρατηρήθηκαν επίσης για το οξείδιο του αζώτου (ΝΟ) (35,12 ± 21,14 έναντι 31,91 ± 16,28 pmol/lt, p=0,01), τα επίπεδα της cGMP (3,79 ± 2,37 έναντι 2,70 ± 1.34 pmol/ml, p<0,001) και τον παράγοντα von Willebrand (956,08 ± 514,25 έναντι 1007,42 ± 466,25 mU/ml) αλλά όχι και για τους άλλους δείκτες που μετρήθηκαν (θρομβομοδουλίνη και Ε-σελεκτίνη). Η στυτική λειτουργία βελτιώθηκε επίσης. Συμπεράσματα: Η σιλδεναφίλη σε καθημερινή χορήγηση βελτιώνει την ενδοθηλιακή λειτουργία όπως αυτή εκτιμάται με τα επίπεδα βιολογικών δεικτών σε ασθενείς με στυτική δυσλειτουργία. Αυτά τα αποτελέσματα συμφωνούν με άλλες μελέτες που δείχνουν όμοια αποτελέσματα με θεραπεία με αναστολείς της φωσφοδιεστεράσης 5. Η κλινική σημασία των αποτελεσμάτων αυτών χρήζει περαιτέρω διερεύνησης. / Objective: To investigate the impact of daily sildenafil on levels of soluble molecular markers of endothelial function in men with erectile dysfunction. Methods: Patients over 18 years of age with erectile dysfunction of vascular aetiology for more than 6 months, either alone or in combination with disease states strongly associated with endothelial dysfunction such as diabetes/metabolic syndrome, hypertension and coronary artery disease, received sildenafil 25 mg orally for 4 weeks. Markers of endothelial function were measured in plasma at baseline and end-of-treatment using standard methods and commercially available kits. Results: 112 men with mean (SD) age of 60.6 (7.3) years completed the protocol. Sildenafil 25mg daily for 4 weeks significantly reduced endothelin-1 levels compared to baseline (2.83 ± 1.63 vs. 3.24 ± 1.90 pg/ml, p<0.001). Significant changes were also observed for nitric oxide (35.12 ± 21.14 vs. 31.91 ± 16.28 pmol/lt, p=0.01) and cyclic guanosine monophosphate (3.79 ± 2.37 vs. 2.70 ± 1.34 pmol/ml, p<0.001) and von Willebrand factor (956.08 ± 514.25 vs. 1007.42 ± 466.25 mU/ml) levels but not for the other biomarkers measured (thrombomodulin and E-selectin). Erectile function was significantly improved. Conclusions: Daily sildenafil improves endothelial function as assessed by levels of biomarkers of endothelial function in patients with erectile dysfunction. This is in agreement with other studies showing similar benefits with phosphodiesterase 5 inhibitor treatment. The clinical implications of this finding need further investigation.

L’hémoglobine est une protéine contenue dans les globules rouges dont la principale fonction est le transport de l’oxygène. Chaque molécule d’hémoglobine est un tétramère constitué de deux paires de globines identiques de type α et β. La β-thalassémie est une maladie génétique hématopoïétique provenant de mutations du gène encodant l'hémoglobine. Ce désordre se caractérise par une diminution ou une absence totale de la synthèse de la chaîne β-globine résultant principalement en une anémie hémolytique sévère ainsi que des complications multisystémiques, telles que la splénomégalie, des déformations osseuses et une dysfonction hépatique et rénale. Actuellement, les transfusions sanguines chroniques représentent le traitement standard des patients β-thalassémiques. Cette thérapie nécessite l’administration conjointe d’un traitement chélateur de fer puisqu’elle entraîne une accumulation pathologique du fer, considéré à ce jour comme la source principale des complications cardiovasculaires de la β-thalassémie. Néanmoins, malgré le traitement efficace de la surcharge de fer transfusionnelle, l’insuffisance cardiaque demeure encore la principale cause de mortalité chez les patients atteints de β-thalassémie. Cette observation indique possiblement la présence d’un mécanisme complémentaire dans le développement de la physiopathologie cardiaque β-thalassémique. L’objectif du présent projet consistait donc à étudier les altérations cardiovasculaires de la β-thalassémie indépendamment de la surcharge de fer transfusionnelle. En utilisant un modèle murin non-transfusé de la β-thalassémie majeure, nous avons d’abord évalué in vivo, par méthode d’imagerie novatrice échographique à haute fréquence, les propriétés hémodynamiques vasculaires. Nos résultats d’index de Pourcelot ainsi que de résistance vasculaire périphérique totale ont démontré une perturbation de l’écoulement microcirculatoire chez les souris β-thalassémiques non-transfusées. Subséquemment, nous avons étudié la fonction endothéliale de régulation du tonus vasculaire de vaisseaux mésentériques isolés. Nos résultats ont révélé un dysfonctionnement de la réponse vasodilatatrice dépendante de l’endothélium chez les souris β-thalassémiques malgré une augmentation de l’expression de l’enzyme de synthèse du monoxyde d’azote ainsi qu’un remodelage de la carotide commune caractérisé par un épaississement de la paroi vasculaire. Finalement, notre étude échocardiographique de la fonction et la morphologie cardiaque a montré, chez les souris β-thalassémiques, le développement d’une hypertrophie et une dysfonction ventriculaire gauche en l’absence de transfusions sanguines chroniques ou de dépôts directs de fer dans le myocarde. L’ensemble des résultats présentés dans le cadre de cette thèse indique la présence d’une pathologie cardiovasculaire chez les souris β-thalassémiques non-transfusés. Nos travaux permettent de proposer un mécanisme de la pathophysiologie cardiovasculaire β-thalassémique, indépendant de la charge de fer transfusionnelle, impliquant les effets compensatoires d’une anémie chronique combinés à une vasculopathie complexe initiée par les érythrocytes endommagés et l’hémolyse intravasculaire. / Hemoglobin is the major protein in red blood cells and is responsible of the oxygen transport. Each hemoglobin molecule is a tetramer consisting of two identical α- and β-globin subunits. β-thalassemia is a genetic hematopoietic disease caused by mutations in hemoglobin genes. This disorder is characterized by a decrease or absence of production of β-globin chain leading mainly to a severe hemolytic anemia and several systemic manifestations, including splenomegaly, skeletal deformities as well as hepatic and renal dysfunctions. Chronic blood transfusions remain the standard treatment for β-thalassemic patients. This therapy requires iron chelating management since it leads to pathological iron accumulation which is currently considered the main cause of cardiovascular complications of β-thalassemia. However, despite adequate control of transfusional iron loading, heart failure remains the leading cause of mortality in β-thalassemia. This issue is possibly indicative of additional pathogenic mechanisms underlying the development of the β-thalassemic cardiac pathology. The objective of the present research project was to study cardiovascular alterations of β-thalassemia independently of transfusional iron overloading. Using an untransfused murine model of β-thalassemia major, we have evaluated in vivo, by non-invasive high-frequency ultrasound imaging, vascular hemodynamic properties. Our results of Pourcelot indices and total peripheral vascular resistance have shown microcirculatory flow disturbances in untransfused β-thalassemic mice. Consequently, we have studied ex vivo the endothelial vasomotor function in isolated mesenteric arterioles. Our findings have pointed out endothelium-dependent vasodilator dysfunction in β-thalassemic mice despite increased expression of nitric oxide synthase, as well as remodeling of the common carotid artery wall. Lastly, our echocardiography studies of heart morphology and function in β-thalassemic mice have demonstrated the development of left ventricle hypertrophy and dysfunction in the absence of chronic blood transfusions or direct myocardial iron deposits. In conclusion, findings presented in this thesis have demonstrated for the first time development of severe cardiovascular complications in untransfused β-thalassemic mice. Based on our results, we have proposed a novel mechanism, independent of direct myocardial iron deposition, responsible for the cardiovascular complications in β-thalassemia. This model combines compensatory effects of chronic anemia with a complex vasculopathy initiated by abnormal erythrocytes and intravascular hemolysis.

Dans le but de vérifier l’impact d’un changement soudain dans l’agrégation érythrocytaire sur certains paramètres cardiovasculaires, une transfusion par échange sanguin du tiers du volume a été effectuée avec du sang hyperagrégeant chez le rat de souche Brown Norway. La pression caudale, le volume cardiaque systolique, la fraction d’éjection, le débit cardiaque, le rythme cardiaque et la résistance périphérique à l’écoulement sanguin ont été observés non-intrusivement sur 19 jours suite à la transfusion. Les rats ont été sacrifiés plus d’un mois suivant la transfusion et une étude ex vivo de la réponse à deux agents dilatateurs (l’acétylcholine et le nitroprussiate de sodium) a été menée sur les artérioles mésentériques. Des variations des paramètres cardiovasculaires, soit le débit, le volume systolique et la résistance périphérique, ont été remarquées dans les trois premiers jours posttransfusion. Une résistance du muscle vasculaire lisse au monoxyde d’azote a été notée chez les rats transfusés au sang hyperagrégeant alors qu’aucune dysfonction endothéliale n’était apparente en réponse à l’acétylcholine. / The aim of this study was to evaluate the effects of an acute change in erythrocyte aggregation on cardiovascular parameters by exchanging one third of the blood volume with hyperaggregating blood in the Brown Norway rat model. Values of caudal pressure, systolic cardiac volume, ejection fraction, cardiac output, heart rate and peripheral resistance to blood flow were observed non-invasively over 19 days after transfusion. The rats were sacrificed after more than a month following the procedure and an ex vivo study in response to pharmacological agents (acetylcholine and sodium nitroprussiate) was performed on mesenteric arterioles. Variations in cardiac output, systolic volume and peripheral resistance were noted for the first three days post-transfusion. The vascular smooth muscles of rats transfused with the hyperaggregating erythrocytes seemed to have developed a resistance to nitric oxide but no endothelial dysfunction was observed in response to acetylcholine.

Cardiovascular disease secondary to atherosclerosis is the most common cause of human morbidity and mortality. An early and fundamental event in the development of atherosclerosis is abnormal vascular endothelial and smooth muscle function. This can be measured by flow mediated dilatation and glyceryl trinitrate mediated dilatation in children at risk of atherosclerosis. Folic acid improves endothelial function (flow mediated dilatation) in adults with coronary artery disease. No studies have previously investigated the effects of folic acid on vascular function in at risk children with diabetes or obesity. In a cross sectional study an evaluation of vascular endothelial and smooth muscle function and their determinants was performed in 159 children with type 1 diabetes, 58 children with obesity, and 53 healthy children. Children with type 1 diabetes and children with mild to moderate obesity had comparable and severe vascular dysfunction but different determinants. Vascular function in healthy and obese children related to both body mass index and weight (adjusted for age and sex), and blood glucose. Children with obesity had lower folate levels and higher homocysteine levels than children with type 1 diabetes, an abnormal lipid profile and raised inflammatory markers. A randomised double blind placebo controlled cross over trial of 8 weeks of folic acid supplementation was performed in 38 children with type 1 diabetes. In these children, folic acid improved endothelial function with a sustained increase in folate levels but independent of homocysteine levels. Folic acid did not improve smooth muscle function. A randomised double blind placebo controlled parallel trial of 8 weeks folic acid supplementation was performed including 53 obese children. Folic acid did not improve vascular function in obese children in spite of sustained increase in folate levels, and a decrease in homocysteine levels. It was concluded that children with type 1 diabetes and obesity have comparable and severe endothelial and smooth muscle function. Determinants of vascular function in children, including weight and glucose, represent a continuum effect. Folic acid supplementation improved endothelial function in children with type 1 diabetes but not in children with obesity, whose metabolic changes causing endothelial dysfunction differ from children with diabetes. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1317003 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A disfunção endotelial tem sido sugerida como evento precoce na patogênese das complicações vasculares do DM1. O presente estudo objetivou avaliar a função endotelial na microcirculação e rigidez arterial no diabetes tipo 1 comparando com controles não diabéticos e correlacionando com variáveis clínicas, demográficas e laboratoriais. Foram avaliados 57 pacientes com diabetes tipo 1 com idade de 32,5 (13-61) anos e duração de doença de 15 (1-48) anos e 53 controles através de fluxometria cutânea por laser-Doppler após iontoforese de Acetilcolina(ACh) (resposta endotélio dependente), hiperemia reativa pós oclusiva(HRPO) e a capacidade máxima de vasodilatação após hiperemia térmica. Já a resposta endotélio independente foi avaliada após iontoforese de Nitroprussiato de sódio (NPS). A rigidez arterial foi mensurada através da análise da onda de pulso digital com os índices de rigidez arterial e de reflexão. Os pacientes diabéticos foram submetidos à avaliação clínica e laboratorial (histórico de tabagismo, dose diária de insulina, duração do diabetes, uso de drogas que alteram a função endotelial como anti-hipertensivos e estatinas, níveis pressóricos, índice de massa corporal, excreção urinária de albumina, perfil lipídico, controle glicêmico e níveis de proteína C-reativa). O fluxo microvascular médio em repouso não foi diferente entre pacientes e controles , assim como a complacência arterial mensurada através do índice de rigidez arterial e do índice de reflexão. A resposta vascular a vasodilatação mediada pela ACh encontrou-se significantemente reduzida nos pacientes (p=0,002). No entanto, apesar da diferença verificada na área abaixo da curva de NPS em relação ao controle, a análise por medidas repetidas não apontou diferença entre os grupos em relação às doses entre os grupos (p=0,15). A vasodilatação cutânea máxima induzida pela hiperemia térmica foi maior entre os controles em comparação com os diabéticos &#61677;93,6(24,5-379-,9) e 56,6(31,5-204,5), respectivamente p=0,04&#61693;. Por outro lado, durante a HRPO, o aumento máximo no fluxo e a área abaixo da resposta hiperêmica não divergiram entre pacientes e controles, embora o tempo para alcançar o fluxo máximo tenha sido maior nos diabéticos do que nos controles(p=0,02). As principais variáveis correlacionadas com a microcirculação foram o ácido úrico, a hemoglobina glicada, a idade e a proteína C reativa, e com a rigidez arterial, foram a duração do Diabetes, a Pressão arterial diastólica e o HDL. Apesar da correlação entre o uso de drogas com propriedades hemorreológicas e a rigidez arterial, a exclusão dos pacientes usuários daqueles medicamentos não alterou os resultados obtidos. Concluímos que, na população de diabéticos tipo 1 estudada, a resposta vascular endotélio dependente, e a capacidade máxima de vasodilatação estão significativamente reduzidas. Não houve diferença entre diabéticos e controles quanto à rigidez arterial. Ademais, a vasodilatação microcirculatória mediada pela Acetilcolina pode ser correlacionada com a rigidez arterial em diabéticos. Estudos posteriores devem ser realizados no intuito de avaliar a influência exercida pelas drogas que alteram a função endotelial sobre a reatividade micro e macrovascular. / Endothelial dysfunction in patients with type 1 diabetes appears to be an early event in the genesis of vascular complications. The purpose of the present study is to assess endothelial function in the microcirculation and arterial stiffness, by comparing with non-diabetic controls, and correlating with clinical, demographic and laboratorial parameters. We evaluated 57 patients with type 1 diabetes aged 32.5 (13-61) years and with a disease duration of 15 (1-48)years, and 53 controls using laser Doppler flowmetry during low-current iontophoresis of acetylcholine (ACh) (endothelium dependent response), post occlusive reactive hyperemia(PORH) and maximum vasodilator function during thermal hyperemia. Endothelium-independent response was measured after iontophoresis of sodium nitroprusside (SNP).The peripheral pressure waveform was analyzed to assess the arterial stiffness. Diabetic patients underwent clinical and laboratory evaluation (smoking, disease duration, daily insulin dose, use of medications that could improve endothelial function such as antihypertensive drugs and statins, blood pressure, body mass index, urinary albumin excretion, lipid profile, glycemic control and C-reactive protein levels-CRP). Mean resting microvascular flux did not differ between control subjects and patients with type 1 diabetes, as well as arterial stiffness assessed through stiffness index and reflection index. Microvascular response to ACh was significantly reduced in patients (p=0,002). However, despite the reduction ofAUC NPS, the analysis with repeated measures disclosed no difference between the groups in relation to the doses (p=0,15). Maximal skin microvascular vasodilation induced by thermal hyperemia was found to be higher in the control group than among patients (&#61677;93,6(24,5-379-,9) e 56,6(31,5-204,5), respectively p=0,04). On the other hand, during PORH, maximal increase in flux and area under the curve of the hyperemic response did not differ between patients and controls, although the time frame to reach maximum flux and the time to half recovery after hyperemia was longer in patients than in controls (P=0.02) . Uric acid, hba1c, age and CRP were the most important contributing factors to the variation of microvascular reactivity, while disease duration, the diastolic arterial pressure and HDL cholesterol were independently associated to arterial stiffness. Despite the correlation between drugs with hemorheologycal properties and arterial stiffness, the exclusion of patients who were taking such substances did not affect the results. We conclude that in the studied population of type 1 diabetic patients, the endothelium-dependent vascular responses and maximal vasodilator capacity are significantly reduced. In what concerns arterial stiffness, our study disclosed no difference between diabetics and controls. Moreover, Acetylcholine response can be correlated to arterial stiffness in diabetics, and further studies aiming at the evaluation of the micro and macrovascular reactivity should be performed with consumers of drugs which may be likely to affect the endothelial function.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A disfunção endotelial tem sido sugerida como evento precoce na patogênese das complicações vasculares do DM1. O presente estudo objetivou avaliar a função endotelial na microcirculação e rigidez arterial no diabetes tipo 1 comparando com controles não diabéticos e correlacionando com variáveis clínicas, demográficas e laboratoriais. Foram avaliados 57 pacientes com diabetes tipo 1 com idade de 32,5 (13-61) anos e duração de doença de 15 (1-48) anos e 53 controles através de fluxometria cutânea por laser-Doppler após iontoforese de Acetilcolina(ACh) (resposta endotélio dependente), hiperemia reativa pós oclusiva(HRPO) e a capacidade máxima de vasodilatação após hiperemia térmica. Já a resposta endotélio independente foi avaliada após iontoforese de Nitroprussiato de sódio (NPS). A rigidez arterial foi mensurada através da análise da onda de pulso digital com os índices de rigidez arterial e de reflexão. Os pacientes diabéticos foram submetidos à avaliação clínica e laboratorial (histórico de tabagismo, dose diária de insulina, duração do diabetes, uso de drogas que alteram a função endotelial como anti-hipertensivos e estatinas, níveis pressóricos, índice de massa corporal, excreção urinária de albumina, perfil lipídico, controle glicêmico e níveis de proteína C-reativa). O fluxo microvascular médio em repouso não foi diferente entre pacientes e controles , assim como a complacência arterial mensurada através do índice de rigidez arterial e do índice de reflexão. A resposta vascular a vasodilatação mediada pela ACh encontrou-se significantemente reduzida nos pacientes (p=0,002). No entanto, apesar da diferença verificada na área abaixo da curva de NPS em relação ao controle, a análise por medidas repetidas não apontou diferença entre os grupos em relação às doses entre os grupos (p=0,15). A vasodilatação cutânea máxima induzida pela hiperemia térmica foi maior entre os controles em comparação com os diabéticos &#61677;93,6(24,5-379-,9) e 56,6(31,5-204,5), respectivamente p=0,04&#61693;. Por outro lado, durante a HRPO, o aumento máximo no fluxo e a área abaixo da resposta hiperêmica não divergiram entre pacientes e controles, embora o tempo para alcançar o fluxo máximo tenha sido maior nos diabéticos do que nos controles(p=0,02). As principais variáveis correlacionadas com a microcirculação foram o ácido úrico, a hemoglobina glicada, a idade e a proteína C reativa, e com a rigidez arterial, foram a duração do Diabetes, a Pressão arterial diastólica e o HDL. Apesar da correlação entre o uso de drogas com propriedades hemorreológicas e a rigidez arterial, a exclusão dos pacientes usuários daqueles medicamentos não alterou os resultados obtidos. Concluímos que, na população de diabéticos tipo 1 estudada, a resposta vascular endotélio dependente, e a capacidade máxima de vasodilatação estão significativamente reduzidas. Não houve diferença entre diabéticos e controles quanto à rigidez arterial. Ademais, a vasodilatação microcirculatória mediada pela Acetilcolina pode ser correlacionada com a rigidez arterial em diabéticos. Estudos posteriores devem ser realizados no intuito de avaliar a influência exercida pelas drogas que alteram a função endotelial sobre a reatividade micro e macrovascular. / Endothelial dysfunction in patients with type 1 diabetes appears to be an early event in the genesis of vascular complications. The purpose of the present study is to assess endothelial function in the microcirculation and arterial stiffness, by comparing with non-diabetic controls, and correlating with clinical, demographic and laboratorial parameters. We evaluated 57 patients with type 1 diabetes aged 32.5 (13-61) years and with a disease duration of 15 (1-48)years, and 53 controls using laser Doppler flowmetry during low-current iontophoresis of acetylcholine (ACh) (endothelium dependent response), post occlusive reactive hyperemia(PORH) and maximum vasodilator function during thermal hyperemia. Endothelium-independent response was measured after iontophoresis of sodium nitroprusside (SNP).The peripheral pressure waveform was analyzed to assess the arterial stiffness. Diabetic patients underwent clinical and laboratory evaluation (smoking, disease duration, daily insulin dose, use of medications that could improve endothelial function such as antihypertensive drugs and statins, blood pressure, body mass index, urinary albumin excretion, lipid profile, glycemic control and C-reactive protein levels-CRP). Mean resting microvascular flux did not differ between control subjects and patients with type 1 diabetes, as well as arterial stiffness assessed through stiffness index and reflection index. Microvascular response to ACh was significantly reduced in patients (p=0,002). However, despite the reduction ofAUC NPS, the analysis with repeated measures disclosed no difference between the groups in relation to the doses (p=0,15). Maximal skin microvascular vasodilation induced by thermal hyperemia was found to be higher in the control group than among patients (&#61677;93,6(24,5-379-,9) e 56,6(31,5-204,5), respectively p=0,04). On the other hand, during PORH, maximal increase in flux and area under the curve of the hyperemic response did not differ between patients and controls, although the time frame to reach maximum flux and the time to half recovery after hyperemia was longer in patients than in controls (P=0.02) . Uric acid, hba1c, age and CRP were the most important contributing factors to the variation of microvascular reactivity, while disease duration, the diastolic arterial pressure and HDL cholesterol were independently associated to arterial stiffness. Despite the correlation between drugs with hemorheologycal properties and arterial stiffness, the exclusion of patients who were taking such substances did not affect the results. We conclude that in the studied population of type 1 diabetic patients, the endothelium-dependent vascular responses and maximal vasodilator capacity are significantly reduced. In what concerns arterial stiffness, our study disclosed no difference between diabetics and controls. Moreover, Acetylcholine response can be correlated to arterial stiffness in diabetics, and further studies aiming at the evaluation of the micro and macrovascular reactivity should be performed with consumers of drugs which may be likely to affect the endothelial function.

La dysfonction endothéliale vasculaire, processus majeur initiant l’athérosclérose, est étroitement liée à l’altération de la synthèse et/ou biodisponibilité du monoxyde d’azote (NO), dont l’arginine est le précurseur. Elle apparait aussi dès la phase postprandiale après un repas gras et sucré. Chez des sujets avec des facteurs de risque cardiométabolique, une supplémentation orale en arginine a un effet bénéfique sur des fonctions associées au NO. Aucune donnée ne permet cependant de lier la mise à disposition de l’arginine et la synthèse de NO, en situation normale ou de risque cardiométabolique. De plus, peu d’études ont étudié l’effet d’une supplémentation en arginine, dans un contexte nutritionnel (faible dose et libération lente) chez des sujets avec des facteurs de risque cardiométabolique. Ce travail vise donc à évaluer l’effet d’une supplémentation nutritionnelle en arginine, sur le métabolisme de l’arginine et la fonction endothéliale (FE), chez des sujets sains présentant des facteurs de risque cardiométabolique. Dans une première étude clinique, nous avons ainsi comparé la biodisponibilité de l’arginine ingérée et son utilisation pour la synthèse de NO, selon la présence de facteurs de risque cardiométabolique, et selon qu’elle était consommée sous une forme à libération immédiate (LI) ou sous une forme à libération prolongée (LP), mimant la mise à disposition naturelle de l’arginine alimentaire. Puis, dans une deuxième étude clinique, nous avons étudié l’effet de la supplémentation en arginine LP sur la FE à jeun et sur son altération postprandiale, chez des sujets sains présentant des facteurs de risque cardiométabolique; et si cet effet pourrait varier selon leur argininémie basale. Ce travail de thèse a ainsi mis en évidence une utilisation de l’arginine ingérée plus élevée pour la synthèse de NO chez les sujets avec des facteurs de risque cardiométabolique, et plus élevée avec la forme LP qu’avec la forme LI, en particulier chez ces sujets à risque. La deuxième étude, quant à elle, a révélé que les effets de la supplémentation en arginine-LP variaient selon l’argininémie basale des sujets présentant des facteurs de risque cardiométabolique. Chez les sujets avec une argininémie basale relativement plus faible, l’arginine-LP a atténué la diminution postprandiale de la FE et a conduit à une FE significativement meilleure à la fin de la période postprandiale. / Vascular endothelial dysfunction, the hallmark of early atherosclerosis, results from an impairment of the synthesis and/or bioavailability of nitric oxide (NO), the precursor of which is arginine. Endothelial dysfunction is also known to be induced transiently by a high-fat meal. In subject with cardiometabolic risk factors, oral arginine supplementation has a beneficial effect on NO-related physiological functions. However, no data relates the availability of arginine to the synthesis of NO in normal or cardiometabolic risk condition. In addition, few studies only have investigated the effect of arginine supplementation in a nutritional context (low dose and slow release) in subjects with cardiometabolic risk factors. This work aims to evaluate the effect of a nutritional arginine supplementation, on the arginine metabolism and endothelial function in healthy subjects with cardiometabolic risk factors. In a first clinical study, we have compared the bioavailability of oral arginine and its utilization for NO synthesis, as a function of the presence of cardiometabolic risk factors, and as a function of the form of release (immediate release, IR, as free arginine, or sustained release, SR, which mimics the slow release of dietary arginine). Then, in a second clinical study, we studied the effect of SR-arginine supplementation on fasting endothelial function and its postprandial alteration in healthy subjects with cardiometabolic factors. A further aim was to investigate whether this effect may vary according to the baseline arginine status of subjects. This thesis work has demonstrated a higher utilization of oral arginine for NO synthesis in subjects with cardiometabolic risk factors, and a higher utilization with the SR form, particularly in these subjects at risk. As to the second study, it showed that the SRarginine supplementation effects largely varied with baseline fasting arginine concentration of subjects with cardiometabolic risk factors. In subjects with a relatively lower baseline arginine concentration, SR-arginine attenuated the decrease in postprandial endothelial function and led to a significantly higher endothelial function at the end of the postprandial period.

Les femmes diabétiques de type 2 présentent un risque cardiovasculaire (CV) plus élevé que les hommes diabétiques de type 2, mais peu d’études s’intéressent au sexe féminin dans ce contexte. L’objectif de ce doctorat était i) d’étudier les altérations CV induites par le prédiabète/diabète de type 2 dans le sexe féminin ; ii) de proposer une approche thérapeutique par le Resvératrol (RSV) chez des rates diabétiques de type 2 ; et iii) d’étudier l’effet du sexe sur les modifications physiologiques induites lors d’un prédiabète et sur la tolérance myocardique à un épisode d’ischémie-reperfusion (IR). Nous avons utilisé le rat prédiabétique induit par un régime riche en graisse et en sucre (HFS), et le rat Goto-Kakizaki (GK) diabétique de type 2. Nous avons réalisé des expériences d’imagerie, de spectroscopie par résonance magnétique in vivo et ex vivo et des analyses biochimiques. Nous avons mis en évidence un épaississement et une augmentation de la perfusion myocardiques chez les femelles HFS, ainsi qu’une forte sensibilité myocardique à un épisode d’IR, impliquant un stress oxydant exacerbé. Le RSV a induit chez les femelles GK une cardioprotection en augmentant les composés riches en énergie et les protéines de la voie du monoxyde d’azote lors d’un épisode d’IR. Enfin, il n’y a pas de dimorphisme sexuel dans la tolérance myocardique à un épisode d’IR lors d’un prédiabète, bien que le régime HFS ait induit des modifications physiologiques différentes selon le sexe. En conclusion, nous avons montré que les dysfonctions endothéliale et mitochondriale jouent un rôle important dans les complications CV associées au diabète de type 2 dans le sexe féminin. / Type 2 diabetic women have a higher cardiovascular (CV) risk than type 2 diabetic men, but few studies focus on the female sex in this context. The objective of this PhD was i) to study CV alterations induced by prediabetes/type 2 diabetes in female; ii) to propose a therapeutic approach by Resveratrol (RSV) in type 2 diabetic female; and iii) to study the effect of sex on the prediabetes-induced physiological modifications and on the myocardial tolerance to ischemia-reperfusion (IR) injury. We used the prediabetic rat induced by a high-fat high-sucrose diet (HFS), and the type 2 diabetic Goto-Kakizaki rat (GK). We performed in vivo and ex vivo cardiovascular magnetic resonance imaging and spectroscopy experiments and biochemical analyses. We highlighted myocardial thickening and increased perfusion in female HFS, as well as high myocardial sensitivity to IR involving exacerbated oxidative stress. RSV treatment of female GK induced cardioprotection by increasing the high-energy compounds and the proteins of the nitric oxide pathway during IR injury. Finally, there was no sexual dimorphism in myocardial tolerance to IR injury in prediabetes, although the HFS diet induced sex-specific physiological changes. In conclusion, we have shown that endothelial and mitochondrial dysfunctions play an important role in CV complications associated to type 2 diabetes in the female sex.