Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-12-06T17:23:43Z No. of bitstreams: 1 NataliaMandarino.pdf: 1259793 bytes, checksum: 4c22457bb7148f23dd689ff0d6e19abc (MD5) / Made available in DSpace on 2017-12-06T17:23:43Z (GMT). No. of bitstreams: 1 NataliaMandarino.pdf: 1259793 bytes, checksum: 4c22457bb7148f23dd689ff0d6e19abc (MD5) Previous issue date: 2017-09-05 / FAPEMA / The role of vitamin D in the regulation of bone metabolism is already well established. However, in recent years, the role of vitamin D in extraskeletal health has been widely explored. In the cardiovascular area, vitamin D deficiency has been independently associated with the occurrence of myocardial infarction, stroke and cardiovascular death. The mechanisms to explain the association between hypovitaminosis D and cardiovascular disease are still not fully understood, and their association with atherosclerosis is postulated. However, studies attempting to correlate hypovitaminosis D with atherosclerosis markers have produced conflicting results, in the same way as small randomized trials of oral supplementation to evaluate intermediate outcomes, so there is currently considerable debate about whether hypovitaminosis D represents a new risk or would be just an inflammatory marker. In the first article, a comprehensive review was made of the role of vitamin D deficiency in the pathogenesis of cardiovascular disease, from basic aspects of its biosynthesis to the results of interventional studies, through its oral supplementation. The second article presents the results of a cross - sectional analysis of 382 individuals living in quilombola communities in Alcântara - MA, participants of the PREVRENAL cohort, presenting at least one cardiovascular risk factor, with a mean age of 57.79 (± 15.3) years and a slight predominance, in which the serum levels of 25-hydroxyvitamin D, the stable circulating form of the vitamin, were correlated with an established marker of subclinical atherosclerosis, carotid intima-media thickness, and other cardiovascular risk factors. Socio-demographic, lifestyle, anthropometric and clinical data were collected and biochemical tests were performed, including the dosage of 25-hydroxyvitamin D by means of the electrochemiluminescence assay. The urinary excretion of albumin was evaluated by means of the albumin / creatinine ratio in an isolated sample of urine. Hypovitaminosis D was defined as serum 25- hydroxyvitamin D levels <30 ng / mL. All participants underwent examination of the common carotid arteries by high-resolution ultrasonography to measure the intimamedia thickness, and the mean of the measurements on both sides was adopted. Serum levels of 25-hydroxyvitamin D were 50.4 (± 13.5) ng / mL, with a low prevalence of hypovitaminosis D (<5%). By simple linear correlation, there was a significant inverse association between 25-hydroxyvitamin D levels and carotid intima-media thickness (r = -0.174, p = 0.001). However, after multiple regression analysis, only the variables male gender, age, smoking, systolic blood pressure, fasting blood glucose and LDL-cholesterol remained significantly associated with carotid intima-media thickness. Levels of 25-hydroxyvitamin D were independently associated positively with HDL-cholesterol and inversely with urinary albumin excretion. In conclusion, in this Afrodescendant population, with a low prevalence of hypovitaminosis D, there was no independent association between serum 25- hydroxyvitamin D levels and carotid intima-media thickness, a finding that contradicts the hypothesis of its antiatherosclerotic role. On the other hand, its positive association with HDL-cholesterol and the inverse association with urinary albumin excretion, also considered as an independent predictor of cardiovascular events, does not allow the exclusion of cardiovascular protection actions of the vitamin in this population profile. / O papel da vitamina D na regulação do metabolismo ósseo já está bem estabelecido. Entretanto, nos últimos anos, o papel da vitamina D na saúde extraesquelética tem sido amplamente explorado. Na área cardiovascular, a deficiência de vitamina D tem sido associada de forma independente à ocorrência de infarto do miocárdio, acidente vascular cerebral e morte cardiovascular. Os mecanismos para explicar a associação entre hipovitaminose D e doença cardiovascular ainda não estão de todo esclarecidos, sendo postulada sua vinculação com a aterosclerose. No entanto, estudos procurando correlacionar hipovitaminose D com marcadores de aterosclerose têm produzido resultados conflitantes, da mesma forma que pequenos estudos randomizados de suplementação oral para avaliar desfechos intermediários, de modo que há atualmente considerável debate acerca de se a hipovitaminose D representa um novo fator de risco ou seria apenas um marcador inflamatório. No primeiro artigo, já publicado, procurou-se realizar uma revisão abrangente sobre o papel da deficiência de vitamina D na patogenia da doença cardiovascular, incluindo desde aspectos básicos de sua biossíntese até os resultados de estudos de intervenção, por meio de sua suplementação oral. O segundo artigo apresenta os resultados de uma análise transversal de 382 indivíduos habitantes de comunidades quilombolas em Alcântara - MA, participantes da coorte PREVRENAL, apresentando pelo menos um fator de risco cardiovascular, com média de idade de 57.79 (± 15.3) anos e discreto predomínio do sexo feminino, em que se procurou correlacionar os níveis séricos de 25-hidroxivitamina D, a forma circulante estável da vitamina, com um marcador estabelecido de aterosclerose subclinica, a espessura médio-intimal carotídea, e outros fatores de risco cardiovascular. Foram coletados dados sócio-demográficos, sobre estilo de vida, antropométricos e clínicos e realizados exames bioquímicos, incluindo a dosagem de 25-hidroxivitamina D, por meio do ensaio eletroquimioluminiscência. A excreção urinária de albumina foi avaliada por meio da razão albumina / creatinina em amostra isolada de urina. Hipovitaminose D foi definida como níveis séricos de 25-hidroxivitamina D <30 ng / mL. Todos os participantes foram submetidos a exame das artérias carótidas comuns por ultrassonografia de alta resolução para medida da espessura médio-intimal, sendo adotada a média das medidas de ambos os lados. A média dos níveis séricos de 25-hidroxivitamina D foi de 50.4 (± 13.5) ng / mL, observando-se uma baixa prevalência de hipovitaminose D (<5%). Por correlação linear simples, observou-se uma associação inversa significativa entre os níveis de 25-hidroxivitamina D e a espessura médio-intimal carotídea (r = -0.174, p = 0.001). Entretanto, após análise de regressão múltipla, apenas as variáveis sexo masculino, idade, tabagismo, pressão arterial sistólica, glicemia em jejum e LDL-colesterol permaneceram significativamente associadas com a espessura médio-intimal carotídea. Níveis de 25-hidroxivitamina D se associaram independentemente, de forma positiva com o HDL-colesterol, e inversa com a excreção urinária de albumina. Em conclusão, nesta população afrodescendente, com baixa prevalência de hipovitaminose D, não se observou uma associação independente entre os níveis séricos de 25- hidroxivitamina D e a espessura médio-intimal carotídea, achado que contraria a hipótese do seu papel antiaterosclerótico. Por outro lado, a sua associação positiva com o HDL-colesterol e inversa com a excreção urinária de albumina, também considerada um preditor independente de eventos cardiovasculares, não permite afastar ações de proteção cardiovascular da vitamina neste perfil populacional.

The mechanical properties of the arterial wall are of great importance for blood pressure regulation and cardiac load. With increasing age, large arteries are affected by increased wall stiffness. Furthermore, atherosclerotic manifestations may increase the stiffness even further, both processes acting as independent cardiovascular risk factors affecting the arterial system in a heterogeneous way. The aims of this thesis was to characterize the local mechanical properties of brachial artery (BA) with the aid of ultrasound technique and to evaluate the influence of 1) age, gender, sympathetic stimulation and examination site; 2) type 1 diabetes (DM) and its association to circulatory biomarkers; and 3) to evaluate the general properties of the arterial system with the aid of pulse wave velocity (PWV) as well as pulse wave analysis (PWA) in systemic lupus erythematosus (SLE) and correlate the findings to disease activity and circulatory biomarkers. In the most proximal arterial segment of the upper arm a pronounced age-related decrease in wall distensibility, increase in intima-media thickness (IMT), and a slight increase in diameter were seen. Sympathetic stimulation had no influence on wall mechanics. More distally in BA, no change in diameter, and only minor increase in IMT and decrease in distensibility were seen. No gender differences were found. These findings suggest that the principle transit zone between elastic and muscular artery behaviour is located in the proximal part of the upper arm. Women with uncomplicated insulin-dependent DM had similar diameter, IMT and distensibility in their distal BA as controls, whereas flow-mediated dilatation (FMD) was slightly, and nitrate mediated dilatation (NMD) markedly reduced. NMD was negatively correlated with higher HbA1c levels. Vascular smooth muscle cell function seems to be an early manifestation of vascular disease in women with DM, influenced by long-term hyperglycaemia. Women with SLE had increased aortic PWV compared to controls, a finding positively associated with increased levels of complement factor 3 (C3), but not with disease activity. The increased stiffness of central arteries may be one factor contributing to the increased cardiovascular risk seen in SLE.