• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 22
  • 19
  • 9
  • 6
  • 5
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 79
  • 79
  • 48
  • 38
  • 32
  • 25
  • 23
  • 22
  • 20
  • 20
  • 15
  • 13
  • 12
  • 10
  • 9
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Elektronicky komutovaný motor / The electronic commutation motor

Bláha, Martin January 2008 (has links)
This work discusses about nowadays problematic of the electronic comutation motors.This work also describes the opportunity of electronic control of these motors. The result of this work is realization of electronic control circuit from discreet components. There also are mentioned is proposal of electronic control board from SMD components. This control board include temperature control with ventilator switching , commutation logic, PWM speed control. In the last part of this paper are results of evaluation measurements of EC motor.
72

Charakteristika velkých tepen u primární a sekundární - endokrinní hypertenze / Large artery properties in primary and secondary - endocrine hypertension

Rosa, Ján January 2011 (has links)
Arterial stiffness represented by carotid-femoral pulse wave velocity (PWV) is considered to be an independent cardiovascular risk factor. This study was focused on large artery properties investigation in specific forms of hypertension using applanation tonometer Sphygmocor (Atcor Medical). PWV was significantly higher in resistant hypertension patients when compared to moderate essential hypertension (EH) patients. This difference appears to be independent of clinical blood pressure (BP). Night-time BP appears to be a more accurate predictor of PWV in EH. In another study we demonstrated that primary hyperparathyroidism (PH) (both hypertensive or non-hypertensive forms) might be associated with higher PWV when compared to EH patients or to normotensive controls and that this difference is independent of age and clinical BP. Neither calcium serum level, nor parathyroid hormone has been associated with PWV. Specific treatment by parathyroidectomy (PTX) seems to be beneficial for PWV decrease, which might be mainly determined by improved BP control after surgery. Since PTX indications for asymptomatic forms of PH have been discussed, our data suggest the potential benefit to the extent of subclinical organ damage after surgical treatment in these patients. Similarly, we prooved higher PWV in...
73

Focalisation des ondes électromagnétiques pour la transmission d'énergie sans fil / Wireless energy transmission by focusing electromagnetic waves

Ibrahim, Rony 17 November 2017 (has links)
La plupart des développements récents dans la transmission d'énergie sans fil utilisant des ondes électromagnétiques se concentre sur les systèmes de récupération de l'énergie électromagnétique par les systèmes sans fil, tels que les réseaux WiFi. Cependant, la nature intermittente et imprévisible de ces sources ambiantes rend la récupération d'énergie critique pour certaines applications. Dans ce contexte, le transfert d'énergie sans fil sur des distances considérables grâce aux micro-ondes permet le réveil à distance et l'alimentation durable des dispositifs électroniques se trouvant dans une myriade d'applications omniprésentes dans un mode de vie en évolution constante. L'alimentation d'un dispositif électronique sans fil élimine la nécessité de batterie, ce qui réduit sa taille et son coût. Les travaux présentés dans cette thèse s'inscrivent dans la thématique de la Transmission d'Énergie Sans Fil (TESF) dans les milieux intérieurs. Dans les scénarios où l'énergie est transmise volontairement par des microondes, les systèmes utilisant des ondes continues ne sont pas nécessairement les plus efficaces. L'objectif est de réaliser un système complet de TESF avec la focalisation des ondes électromagnétiques (EM) sur le récepteur afin d'augmenter le rendement du transfert énergétique global. Les études présentées durant cette thèse montrent que la technique du Retournement Temporel (RT) se trouve être optimale pour la focalisation des ondes EM. Sa mise en œuvre s'effectue en deux phases. Dans une première phase dite phase d'apprentissage, une impulsion de faible énergie est transmise par une antenne à un autre endroit du milieu. L'antenne réceptrice enregistre un signal constitué d'une succession d'impulsions retardées, plus ou moins atténuées, et liées aux réflexions dans le milieu. Dans une deuxième phase, appelée phase de focalisation, un signal de haute énergie construit à partir du retournement temporel du signal enregistré est transmis par l'une des antennes. À l'aide de cette approche, il en résulte que le signal retourné temporellement se focalise spatio-temporellement sur l'antenne réceptrice sous forme d'une onde pulsée (PW). Ces propriétés sont particulièrement importantes pour la TESF. Au niveau du circuit récepteur, la rectenna (antenne-redresseur) est le dispositif permettant de capter et convertir les PW focalisées en tension continue. Dans ce projet de recherche, une nouvelle rectenna à base des diodes Schottky avec une architecture de doubleur de courant a été conçue, développée et optimisée afin de garantir les performances optimales de conversion des PW. Des mesures expérimentales réalisées démontrent un fonctionnement très performant prédit par la procédure de conception. De plus, les performances obtenues se distinguent parfaitement vis-à-vis de résultats recensés dans l'état de l'art, ce qui fait de ces travaux une innovation. / Most recent developments in Wireless Energy Transmission (WET) using electromagnetic (EM) waves focus on designing systems to recover the electromagnetic energy lost by common wireless systems such as Wi-Fi networks. However, the intermittent and unpredictable nature of these ambient sources makes harvesting energy critical for some applications. Hence, the WET over considerable distances using microwaves appears in this context allowing the remote wake-up and wireless powering of electronic devices in a myriad of applications that are a part of the constantly evolution of the way of life. Wireless powering of an electronic device eliminates the need of the battery, which reduces its size and cost. The work presented in this thesis belong to the WET in indoor environments field. When energy is voluntarily transmitted by microwaves, systems using continuous waves are not necessarily the most efficient. The aim of this research project is to achieve a complete WET system by focusing of EM waves at the receiver in order to increase the overall energy transfer efficiency. The studies presented during this thesis show that the time reversal technique (TR) is optimal for the focusing of EM waves. The procedure is carried out in two stages. In the first stage called \textit{learning stage}, a low energy pulse is transmitted by an emitting antenna. Another antenna placed in other location in the medium receives and records a signal made of a succession of delayed pulses, more or less attenuated, and related to reflections on the environment. In a second stage called \textit{focusing stage}, a high-energy signal constructed from the time reversal of the recorded signal is transmitted by one of the antennas. Using this technique, it results that the temporally inverted signal focuses spatio-temporally on the receiving antenna in the form of a Pulsed Wave (PW). These properties are particularly important for the WET. At the receiver circuit, the \textit{rectenna} (rectifying antenna) is the device for capturing and converting focused PW to DC voltage. In this research project, we introduce a novel rectenna design based on Schottky diodes with a current-doubler topology designed, developed and optimized to ensure optimum conversion performance of PW. Experimental measurements demonstrate good performance predicted by the design procedure. Moreover, the performances obtained are perfectly distinct from those found in the state of the art, making this work an innovation in WET domain.
74

Associação entre doença tireoidiana subclínica, aterosclerose coronariana, índice de espessura de médio-íntima carotídea e rigidez arterial aórtica em análise transversal do Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil) / Association between subclinical thyroid disease, coronary atherosclerosis, carotid intima-media thickness and aortic arterial stiffness in cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Miranda, Érique José Peixoto de 23 March 2017 (has links)
Introdução: Doenças tireoidianas subclínicas incluem hipotireoidismo e hipertireoidismo subclínicos. A associação entre doença tireoidiana subclínica e morbimortalidade cardiovascular é controversa e os dados sobre a relação entre essas condições clínicas e aterosclerose subclínica são escassos. Objetivos: Este estudo objetiva avaliar a associação entre doença tireoidiana subclínica, calcificação arterial coronariana (CAC), doença arterial coronariana (DAC), índice de espessura de médio-íntima carotídea média (IMT) e velocidade de onda de pulso carotídeo-femoral (cf-VOP) no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Métodos: Incluímos sujeitos eutireóideos, definidos como tendo TSH entre 0,4 e 4,0 mUI/L e T4L entre 0,8 e 1,9ng/dL, indivíduos com hipotireoidismo subclínico, definido como TSH > 4,0 mUI/L e T4L normal, e hipertireoidismo subclínico, definido como TSH < 0,4 mUI/L e T4L normal. Excluímos os indivíduos com as demais disfunções tireoidianas, em uso de medicação que altera a função tireoidiana, e com doença cardiovascular prévia. Na análise de angiotomografia, excluímos também os sujeitos com hipertireoidismo subclínico pelo pequeno número que impedia a análise e, na análise de cf-VOP, doença renal crônica, indivíduos em uso de diuréticos e de anti-hipertensivos. As associações entre quintis de TSH, CAC > 100 e DAC foram avaliadas por regressão logística e as associações entre IMT, VOP (como variáveis contínuas ou categorizadas com ponto de corte no percentil 75 amostral) e níveis de TSH ou doenças tireoidianas subclínicas foram avaliadas por regressões logísticas e lineares multivariadas. Todos os modelos foram ajustados por variáveis demográficas e fatores de risco cardiovasculares. Resultados: A análise de CAC incluiu 3.836 sujeitos, mediana de idade de 49 anos (IQR=44-56), 1.999 (52,1%) mulheres. CAC > 100 associou-se independentemente com o primeiro quintil (OR ajustado=1,57, IC 95%=1,05-2,35, P=0,027), usando o terceiro como referência. Na análise de angiotomografia, foram incluídos 796 sujeitos, mediana de idade de 55 anos (IQR=48-60 anos), 406 (51%) mulheres. O primeiro quintil associou-se independentemente com CAC (OR ajustado=1,76, IC 95%=1,09-2,82, P= 0,02), DAC (OR ajustado=1,73, IC 95%=1,08-2,79, P=0,023), mas não com extensão de doença. Na análise de IMT, foram incluídos 8.623 sujeitos, mediana de idade de 50 anos (IQR=45-57 anos), 4.624 (53,6%) mulheres, na subanálise de hipotireoidismo subclínico, e 8.193, com mediana de idade de 50 anos (IQR=44-57 anos), 4.382 (53,5%) mulheres, na subanálise de hipertireoidismo subclínico. Hipotireoidismo subclínico, mas não hipertireoidismo subclínico, associou-se ao IMT como variável contínua (beta=0,010, IC 95%=0,0004-0,019, P=0,041) e categorizado no percentil 75 ajustado para sexo, idade e raça (OR ajustado=1,30, IC95%=1,07-1,61, P=0,010). Na análise de cf-VOP, foram incluídos 8.341 sujeitos, mediana de idade de 50 anos (IQR=44-56 anos), 4.383 (52,5%) mulheres, na subanálise de hipotireoidismo subclínico, e 7.790, mediana de idade de 50 anos (IQR=44-57 anos), 4.191 (53,8%) mulheres, na subanálise de hipertireoidismo subclínico. Cf-VOP não se associou com doença tireoidiana subclínica. Conclusões: Em análises diferentes, CAC e DAC associaram-se com primeiro quintil de TSH usando-se o terceiro como referência. O IMT associou-se com hipotireoidismo subclínico e a cf-VOP não se associou com disfunção tireoidiana subclínica / Introduction: Subclinical thyroid disease includes subclinical hypothyroidism and subclinical hyperthyroidism. Association between subclinical thyroid disease and cardiovascular morbidity and mortality is controversial and data about the relationship between those clinical conditions and subclinical atherosclerosis is scarce. Objectives: This study aims to evaluate the association between subclinical thyroid disease, coronary artery calcification (CAC), coronary artery disease (CAD), mean common carotid intima-media thickness (IMT) and carotid-femoral pulse wave velocity (cf-PWV) in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods: We included euthyroid subjects, defined as TSH between 0.4 and 4.0 mIU/l and FT4 between 0.8 and 1.9 ng/dL, and individuals with subclinical hypothyroidism, defined as TSH > 4.0 mIU/l and normal FT4, and subclinical hyperthyroidism, defined as TSH < 0.4 mIU/L and normal FT4. We excluded individuals with other thyroid disorders, subjects who used medication that altered thyroid function, subjects with past of cardiovascular disease. In computed angiotomography analysis, we have excluded subjects with subclinical hyperthyroidism because of the small sample, and in cf-PWV analysis, we have excluded individuals with chronic kidney disease, use of anti-hypertensive and diuretics. The association between TSH quintiles was evaluated in logistic regression models for CAC and CAD, and the association between IMT, cf-PWV (as continuous variables or as factor, categorized at 75th sample\'s percentile) and TSH levels or subclinical thyroid diseases was evaluated by multivariate logistic and linear regression models. All models were adjusted for demographic variables and cardiovascular risk factors. Results: CAC analysis included 3,836 subjects, median of age 49 years (IQR=44-56), 1,999 (52.1%) women. CAC > 100 was independently associated with first quintile of TSH, using the third quintile as the reference (adjusted OR=1.57, 95% CI=1.05-2.35, P=0.027). Computed angiotomography analysis included 796 subjects, median of age 55 years (IQR=48-60), 406 (51%) women. CAD and CAC > 0 was independently associated with first quintile in comparison with third quintile (adjusted OR=1.73, 95% CI=1.08-2.79, P=0.023 and adjusted OR=1.76, 95% CI=1.09-2.82, P= 0.02, respectively), but not with burden of disease. In IMT analysis, 8,623 subjects were included, median of age 50 years (IQR=45-57 years), 4,624 (53.6%) women in the subclinical hypothyroidism subanalysis, and 8,193, median age 50 years (IQR = 44-57 years), 4,382 (53.5%) women, in the subclinical hyperthyroidism subanalysis. Subclinical hypothyroidism, but not subclinical hyperthyroidism, was independently associated with IMT as continuous variable (beta=0.010, IC 95%=0.0004-0.019, P=0.041) or as factor categorized at 75th percentile adjusted for age, sex and race (adjusted OR=1.30, 95% CI=1.07-1.61, P=0.010). In cf-PWV analysis, 8,341 subjects were included, median of age 50 years (IQR=44-56 years), 4,383 (52.5%) women in the subclinical hypothyroidism subanalysis, and 7,790, median age 50 years (IQR = 44-57 years), 4,191 (53.8%) women in subclinical hyperthyroidism subanalysis. Cf- PWV was not associated with subclinical thyroid disease. Conclusion: In separated analysis, CAC and CAD was independently associated with first quintile of TSH using the third as the reference; IMT was independently associated with subclinical hypothyroidism, and cf-PWV was not associated with subclinical thyroid diseases
75

Velocidade da onda de pulso em adultos jovens acompanhados por 18 anos: impacto de variáveis pressóricas, antropométricas, metabólicas, inflamatórias e de função endotelial. Estudo do Rio de Janeiro. / Velocidade da onda de pulso em adultos jovens acompanhados por 18 anos: impacto de variáveis pressóricas, antropométricas, metabólicas, inflamatórias e de função endotelial. Estudo do Rio de Janeiro. / Pulse wave velocity in youngs adults followed for 18 years: impact of blood pressure, anthropometric, inflammatory and endothelial function variables. The Rio de Janeiro study. / Pulse wave velocity in youngs adults followed for 18 years: impact of blood pressure, anthropometric, inflammatory and endothelial function variables. The Rio de Janeiro study.

Oswaldo Luiz Pizzi 29 October 2013 (has links)
Dados sobre a avaliação não invasiva da rigidez vascular e suas relações com variáveis de risco cardiovascular são escassos em jovens. Objetiva avaliar a relação entre a velocidade de onda de pulso (VOP) e a pressão arterial (PA), variáveis antropométricas, metabólicas, inflamatórias e de disfunção endotelial em indivíduos adultos jovens. Foram estudados 96 indivíduos (51 homens) do Estudo do Rio de Janeiro, em duas avaliações, A1 e A2, com intervalo de 17,691,58 anos (16 a 21 anos). Em A1 foram avaliados em suas escolas (10-15 anos - média 12,421,47 anos) e em A2 foram novamente avaliados em nível ambulatorial (26-35 anos - média 30,091,92 anos). Em A1 foram obtidos pressão arterial (PA) e índice de massa corporal (IMC). Em A2 foram obtidos a velocidade da onda de pulso (VOP)-método Complior, PA, IMC, circunferência abdominal (CA), glicose, perfil lipídico, leptina, insulina, adiponectina, o índice de resistência à insulina HOMA-IR, proteína C-Reativa ultrassensível (PCRus) e as moléculas de adesão E-selectina, Vascular Cell Adhesion Molecule-1(VCAM-1) e Intercellular Adhesion Molecule-1 (ICAM-1). Foram obtidos, ainda, a variação da PA e do IMC entre as 2 avaliações. Em A2 os indivíduos foram estratificados segundo o tercil da VOP para cada sexo. Como resultados temos: 1) Os grupos foram constituídos da seguinte forma: Tercil 1:homens com VOP < 8,69 m/s e mulheres com VOP < 7,66 m/s; Tercil 2: homens com VOP &#8805; 8,69 m/s e < 9,65m/s e mulheres com VOP &#8805; 7,66 m/s e < 8,31m/s;Tercil 3:homens com VOP &#8805; 9,65 m/s e mulheres com VOP &#8805; 8,31 m/s. 2) O grupo com maior tercil de VOP mostrou maiores médias de PA sistólica (PAS) (p=0,005), PA diastólica (PAD) (p=0,007), PA média (PAM) (p=0,004), variação da PAD (p=0,032), variação da PAM (p=0,003), IMC (p=0,046), variação do IMC (p=0,020), insulina (p=0,019), HOMA-IR (p=0,021), E-selectina (p=0,032) e menores médias de adiponectina (p=0,016), além de maiores prevalências de diabetes mellitus/intolerância à glicose (p=0,022) e hiperinsulinemia (p=0,038); 3) Houve correlação significativa e positiva da VOP com PAS (p<0,001), PAD (p<0,001), PP (p=0,048) e PAM (p<0,001) de A2, com a variação da pressão arterial (PAS, PAD e PAM) (p<0,001) entre as duas avaliações, com o IMC de A2 (p=0,005) e com a variação do IMC (p<0,001) entre as duas avaliações, com CA (p=0,001), LDLcolesterol (p=0,049) e E-selectina (p<0,001) e correlação negativa com HDLcolesterol (p<0,001) e adiponectina (p<0,001); 4)Em modelo de regressão múltipla, após ajuste do HDL-colesterol, LDLcolesterol e adiponectina para sexo, idade, IMC e PAM, apenas o sexo masculino e a PAM mantiveram correlação significativa com a VOP. A VOP em adultos jovens mostrou relação significativa com variáveis de risco cardiovascular, destacando-se o sexo masculino e a PAM como importantes variáveis no seu determinismo. Os achados sugerem que a medida da VOP pode ser útil para a identificação do acometimento vascular nessa faixa etária. / Data on non-invasive evaluation of vascular stiffness in the young and its relationship with cardiovascular (CV) risk variables are scarce. Objective to assess the relationship between pulse wave velocity (PWV) and blood pressure (BP), anthropometric, metabolic, inflammatory and endothelial dysfunction variables in young adults. Ninety-six individuals (51 males) from The Rio de Janeiro Study cohort were studied in two evaluations, A1 and A2, with an interval of 17.69 1.58 years (16-21 years). In A 1 they were evaluated at their schools (10-15 years average 12.42 1.47 years) and in A2 they were all re-evaluated as outpatients (26-35 years - average 30.09 1.92 years). In A1 BP and body mass index (BMI) were obtained. In A2 pulse wave velocity (PWV) by Complior method, BP, BMI, waist circumference (WC), glucose, lipid profile, leptin, insulin, adiponectin, the HOMA-IR insulin resistance index, high sensitive C-Reactive protein (CRPhs) and E-selectin, Vascular Cell Adhesion Molecule 1 (VCAM-1) and Intercellular Adhesion Molecule 1 (ICAM-1) adhesion molecules were obtained. The BP and BMI variation over the time interval between the two evaluations were also obtained. Subjects were stratified according to tertile of PWV for each sex in A2. As results: 1) The groups were constituted as follows: Tertile 1: males with PWV <8.69 m/s and females with PWV <7.66 m/s; Tertile 2: males with PWV &#8805; 8.69 m/s and <9.65 m/s and females with PWV &#8805; 7.66 m/s and <8.31 m/s; Tertile 3: males with PWV &#8805; 9.65 m/s and females with PWV &#8805; 8.31 m/s 2) The group with the highest PWV tertile showed higher values of systolic BP (SBP) (p=0.005), diastolic BP (DBP) (p=0.007), mean BP (MBP) (p=0,004), DBP variation (p=0,032), MBP variation (p=0.033), BMI (p=0.046), BMI variation (p=0.020), insulin (p=0.019), HOMA-IR (p=0.021), E-Selectin (p=0.032) and lower values of adiponectin (p=0.016), besides higher prevalence of diabetes mellitus/glucose intolerance (p=0.022) and hyperinsulinemia (p=0.038); 3) There were a significant positive correlation of PWV with SBP (p<0,001), DBP (p<0,001), PP (p=0,048) and MBP (p<0,001) from A2, variation in blood pressure (SBP, DBP, and MBP) (p<0,001) between the two assessments, BMI (p=0.005) and BMI variation between the two evaluations (p<0,001), WC (p=0.001), LDL-cholesterol (0.049), and E-selectin (p<0,001) and negative correlation with HDL-cholesterol (p<0,001) and adiponectin (p<0,001); 4) In the multiple regression model, HDL-cholesterol, LDL-cholesterol and adiponectin lost statistical significance after adjustment for sex, age, BMI and MBP, only the male gender and MBP remained significantly correlated with PWV. PWV in young adults showed a significant association with CV risk variables, highlighting the male gender and MBP as important variables in its determining. The findings suggest that measurement of PWV can be useful for the identification of vascular impairment in this age group.
76

Velocidade da onda de pulso em adultos jovens acompanhados por 18 anos: impacto de variáveis pressóricas, antropométricas, metabólicas, inflamatórias e de função endotelial. Estudo do Rio de Janeiro. / Velocidade da onda de pulso em adultos jovens acompanhados por 18 anos: impacto de variáveis pressóricas, antropométricas, metabólicas, inflamatórias e de função endotelial. Estudo do Rio de Janeiro. / Pulse wave velocity in youngs adults followed for 18 years: impact of blood pressure, anthropometric, inflammatory and endothelial function variables. The Rio de Janeiro study. / Pulse wave velocity in youngs adults followed for 18 years: impact of blood pressure, anthropometric, inflammatory and endothelial function variables. The Rio de Janeiro study.

Oswaldo Luiz Pizzi 29 October 2013 (has links)
Dados sobre a avaliação não invasiva da rigidez vascular e suas relações com variáveis de risco cardiovascular são escassos em jovens. Objetiva avaliar a relação entre a velocidade de onda de pulso (VOP) e a pressão arterial (PA), variáveis antropométricas, metabólicas, inflamatórias e de disfunção endotelial em indivíduos adultos jovens. Foram estudados 96 indivíduos (51 homens) do Estudo do Rio de Janeiro, em duas avaliações, A1 e A2, com intervalo de 17,691,58 anos (16 a 21 anos). Em A1 foram avaliados em suas escolas (10-15 anos - média 12,421,47 anos) e em A2 foram novamente avaliados em nível ambulatorial (26-35 anos - média 30,091,92 anos). Em A1 foram obtidos pressão arterial (PA) e índice de massa corporal (IMC). Em A2 foram obtidos a velocidade da onda de pulso (VOP)-método Complior, PA, IMC, circunferência abdominal (CA), glicose, perfil lipídico, leptina, insulina, adiponectina, o índice de resistência à insulina HOMA-IR, proteína C-Reativa ultrassensível (PCRus) e as moléculas de adesão E-selectina, Vascular Cell Adhesion Molecule-1(VCAM-1) e Intercellular Adhesion Molecule-1 (ICAM-1). Foram obtidos, ainda, a variação da PA e do IMC entre as 2 avaliações. Em A2 os indivíduos foram estratificados segundo o tercil da VOP para cada sexo. Como resultados temos: 1) Os grupos foram constituídos da seguinte forma: Tercil 1:homens com VOP < 8,69 m/s e mulheres com VOP < 7,66 m/s; Tercil 2: homens com VOP &#8805; 8,69 m/s e < 9,65m/s e mulheres com VOP &#8805; 7,66 m/s e < 8,31m/s;Tercil 3:homens com VOP &#8805; 9,65 m/s e mulheres com VOP &#8805; 8,31 m/s. 2) O grupo com maior tercil de VOP mostrou maiores médias de PA sistólica (PAS) (p=0,005), PA diastólica (PAD) (p=0,007), PA média (PAM) (p=0,004), variação da PAD (p=0,032), variação da PAM (p=0,003), IMC (p=0,046), variação do IMC (p=0,020), insulina (p=0,019), HOMA-IR (p=0,021), E-selectina (p=0,032) e menores médias de adiponectina (p=0,016), além de maiores prevalências de diabetes mellitus/intolerância à glicose (p=0,022) e hiperinsulinemia (p=0,038); 3) Houve correlação significativa e positiva da VOP com PAS (p<0,001), PAD (p<0,001), PP (p=0,048) e PAM (p<0,001) de A2, com a variação da pressão arterial (PAS, PAD e PAM) (p<0,001) entre as duas avaliações, com o IMC de A2 (p=0,005) e com a variação do IMC (p<0,001) entre as duas avaliações, com CA (p=0,001), LDLcolesterol (p=0,049) e E-selectina (p<0,001) e correlação negativa com HDLcolesterol (p<0,001) e adiponectina (p<0,001); 4)Em modelo de regressão múltipla, após ajuste do HDL-colesterol, LDLcolesterol e adiponectina para sexo, idade, IMC e PAM, apenas o sexo masculino e a PAM mantiveram correlação significativa com a VOP. A VOP em adultos jovens mostrou relação significativa com variáveis de risco cardiovascular, destacando-se o sexo masculino e a PAM como importantes variáveis no seu determinismo. Os achados sugerem que a medida da VOP pode ser útil para a identificação do acometimento vascular nessa faixa etária. / Data on non-invasive evaluation of vascular stiffness in the young and its relationship with cardiovascular (CV) risk variables are scarce. Objective to assess the relationship between pulse wave velocity (PWV) and blood pressure (BP), anthropometric, metabolic, inflammatory and endothelial dysfunction variables in young adults. Ninety-six individuals (51 males) from The Rio de Janeiro Study cohort were studied in two evaluations, A1 and A2, with an interval of 17.69 1.58 years (16-21 years). In A 1 they were evaluated at their schools (10-15 years average 12.42 1.47 years) and in A2 they were all re-evaluated as outpatients (26-35 years - average 30.09 1.92 years). In A1 BP and body mass index (BMI) were obtained. In A2 pulse wave velocity (PWV) by Complior method, BP, BMI, waist circumference (WC), glucose, lipid profile, leptin, insulin, adiponectin, the HOMA-IR insulin resistance index, high sensitive C-Reactive protein (CRPhs) and E-selectin, Vascular Cell Adhesion Molecule 1 (VCAM-1) and Intercellular Adhesion Molecule 1 (ICAM-1) adhesion molecules were obtained. The BP and BMI variation over the time interval between the two evaluations were also obtained. Subjects were stratified according to tertile of PWV for each sex in A2. As results: 1) The groups were constituted as follows: Tertile 1: males with PWV <8.69 m/s and females with PWV <7.66 m/s; Tertile 2: males with PWV &#8805; 8.69 m/s and <9.65 m/s and females with PWV &#8805; 7.66 m/s and <8.31 m/s; Tertile 3: males with PWV &#8805; 9.65 m/s and females with PWV &#8805; 8.31 m/s 2) The group with the highest PWV tertile showed higher values of systolic BP (SBP) (p=0.005), diastolic BP (DBP) (p=0.007), mean BP (MBP) (p=0,004), DBP variation (p=0,032), MBP variation (p=0.033), BMI (p=0.046), BMI variation (p=0.020), insulin (p=0.019), HOMA-IR (p=0.021), E-Selectin (p=0.032) and lower values of adiponectin (p=0.016), besides higher prevalence of diabetes mellitus/glucose intolerance (p=0.022) and hyperinsulinemia (p=0.038); 3) There were a significant positive correlation of PWV with SBP (p<0,001), DBP (p<0,001), PP (p=0,048) and MBP (p<0,001) from A2, variation in blood pressure (SBP, DBP, and MBP) (p<0,001) between the two assessments, BMI (p=0.005) and BMI variation between the two evaluations (p<0,001), WC (p=0.001), LDL-cholesterol (0.049), and E-selectin (p<0,001) and negative correlation with HDL-cholesterol (p<0,001) and adiponectin (p<0,001); 4) In the multiple regression model, HDL-cholesterol, LDL-cholesterol and adiponectin lost statistical significance after adjustment for sex, age, BMI and MBP, only the male gender and MBP remained significantly correlated with PWV. PWV in young adults showed a significant association with CV risk variables, highlighting the male gender and MBP as important variables in its determining. The findings suggest that measurement of PWV can be useful for the identification of vascular impairment in this age group.
77

Associação entre doença tireoidiana subclínica, aterosclerose coronariana, índice de espessura de médio-íntima carotídea e rigidez arterial aórtica em análise transversal do Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil) / Association between subclinical thyroid disease, coronary atherosclerosis, carotid intima-media thickness and aortic arterial stiffness in cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Érique José Peixoto de Miranda 23 March 2017 (has links)
Introdução: Doenças tireoidianas subclínicas incluem hipotireoidismo e hipertireoidismo subclínicos. A associação entre doença tireoidiana subclínica e morbimortalidade cardiovascular é controversa e os dados sobre a relação entre essas condições clínicas e aterosclerose subclínica são escassos. Objetivos: Este estudo objetiva avaliar a associação entre doença tireoidiana subclínica, calcificação arterial coronariana (CAC), doença arterial coronariana (DAC), índice de espessura de médio-íntima carotídea média (IMT) e velocidade de onda de pulso carotídeo-femoral (cf-VOP) no Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil). Métodos: Incluímos sujeitos eutireóideos, definidos como tendo TSH entre 0,4 e 4,0 mUI/L e T4L entre 0,8 e 1,9ng/dL, indivíduos com hipotireoidismo subclínico, definido como TSH > 4,0 mUI/L e T4L normal, e hipertireoidismo subclínico, definido como TSH < 0,4 mUI/L e T4L normal. Excluímos os indivíduos com as demais disfunções tireoidianas, em uso de medicação que altera a função tireoidiana, e com doença cardiovascular prévia. Na análise de angiotomografia, excluímos também os sujeitos com hipertireoidismo subclínico pelo pequeno número que impedia a análise e, na análise de cf-VOP, doença renal crônica, indivíduos em uso de diuréticos e de anti-hipertensivos. As associações entre quintis de TSH, CAC > 100 e DAC foram avaliadas por regressão logística e as associações entre IMT, VOP (como variáveis contínuas ou categorizadas com ponto de corte no percentil 75 amostral) e níveis de TSH ou doenças tireoidianas subclínicas foram avaliadas por regressões logísticas e lineares multivariadas. Todos os modelos foram ajustados por variáveis demográficas e fatores de risco cardiovasculares. Resultados: A análise de CAC incluiu 3.836 sujeitos, mediana de idade de 49 anos (IQR=44-56), 1.999 (52,1%) mulheres. CAC > 100 associou-se independentemente com o primeiro quintil (OR ajustado=1,57, IC 95%=1,05-2,35, P=0,027), usando o terceiro como referência. Na análise de angiotomografia, foram incluídos 796 sujeitos, mediana de idade de 55 anos (IQR=48-60 anos), 406 (51%) mulheres. O primeiro quintil associou-se independentemente com CAC (OR ajustado=1,76, IC 95%=1,09-2,82, P= 0,02), DAC (OR ajustado=1,73, IC 95%=1,08-2,79, P=0,023), mas não com extensão de doença. Na análise de IMT, foram incluídos 8.623 sujeitos, mediana de idade de 50 anos (IQR=45-57 anos), 4.624 (53,6%) mulheres, na subanálise de hipotireoidismo subclínico, e 8.193, com mediana de idade de 50 anos (IQR=44-57 anos), 4.382 (53,5%) mulheres, na subanálise de hipertireoidismo subclínico. Hipotireoidismo subclínico, mas não hipertireoidismo subclínico, associou-se ao IMT como variável contínua (beta=0,010, IC 95%=0,0004-0,019, P=0,041) e categorizado no percentil 75 ajustado para sexo, idade e raça (OR ajustado=1,30, IC95%=1,07-1,61, P=0,010). Na análise de cf-VOP, foram incluídos 8.341 sujeitos, mediana de idade de 50 anos (IQR=44-56 anos), 4.383 (52,5%) mulheres, na subanálise de hipotireoidismo subclínico, e 7.790, mediana de idade de 50 anos (IQR=44-57 anos), 4.191 (53,8%) mulheres, na subanálise de hipertireoidismo subclínico. Cf-VOP não se associou com doença tireoidiana subclínica. Conclusões: Em análises diferentes, CAC e DAC associaram-se com primeiro quintil de TSH usando-se o terceiro como referência. O IMT associou-se com hipotireoidismo subclínico e a cf-VOP não se associou com disfunção tireoidiana subclínica / Introduction: Subclinical thyroid disease includes subclinical hypothyroidism and subclinical hyperthyroidism. Association between subclinical thyroid disease and cardiovascular morbidity and mortality is controversial and data about the relationship between those clinical conditions and subclinical atherosclerosis is scarce. Objectives: This study aims to evaluate the association between subclinical thyroid disease, coronary artery calcification (CAC), coronary artery disease (CAD), mean common carotid intima-media thickness (IMT) and carotid-femoral pulse wave velocity (cf-PWV) in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). Methods: We included euthyroid subjects, defined as TSH between 0.4 and 4.0 mIU/l and FT4 between 0.8 and 1.9 ng/dL, and individuals with subclinical hypothyroidism, defined as TSH > 4.0 mIU/l and normal FT4, and subclinical hyperthyroidism, defined as TSH < 0.4 mIU/L and normal FT4. We excluded individuals with other thyroid disorders, subjects who used medication that altered thyroid function, subjects with past of cardiovascular disease. In computed angiotomography analysis, we have excluded subjects with subclinical hyperthyroidism because of the small sample, and in cf-PWV analysis, we have excluded individuals with chronic kidney disease, use of anti-hypertensive and diuretics. The association between TSH quintiles was evaluated in logistic regression models for CAC and CAD, and the association between IMT, cf-PWV (as continuous variables or as factor, categorized at 75th sample\'s percentile) and TSH levels or subclinical thyroid diseases was evaluated by multivariate logistic and linear regression models. All models were adjusted for demographic variables and cardiovascular risk factors. Results: CAC analysis included 3,836 subjects, median of age 49 years (IQR=44-56), 1,999 (52.1%) women. CAC > 100 was independently associated with first quintile of TSH, using the third quintile as the reference (adjusted OR=1.57, 95% CI=1.05-2.35, P=0.027). Computed angiotomography analysis included 796 subjects, median of age 55 years (IQR=48-60), 406 (51%) women. CAD and CAC > 0 was independently associated with first quintile in comparison with third quintile (adjusted OR=1.73, 95% CI=1.08-2.79, P=0.023 and adjusted OR=1.76, 95% CI=1.09-2.82, P= 0.02, respectively), but not with burden of disease. In IMT analysis, 8,623 subjects were included, median of age 50 years (IQR=45-57 years), 4,624 (53.6%) women in the subclinical hypothyroidism subanalysis, and 8,193, median age 50 years (IQR = 44-57 years), 4,382 (53.5%) women, in the subclinical hyperthyroidism subanalysis. Subclinical hypothyroidism, but not subclinical hyperthyroidism, was independently associated with IMT as continuous variable (beta=0.010, IC 95%=0.0004-0.019, P=0.041) or as factor categorized at 75th percentile adjusted for age, sex and race (adjusted OR=1.30, 95% CI=1.07-1.61, P=0.010). In cf-PWV analysis, 8,341 subjects were included, median of age 50 years (IQR=44-56 years), 4,383 (52.5%) women in the subclinical hypothyroidism subanalysis, and 7,790, median age 50 years (IQR = 44-57 years), 4,191 (53.8%) women in subclinical hyperthyroidism subanalysis. Cf- PWV was not associated with subclinical thyroid disease. Conclusion: In separated analysis, CAC and CAD was independently associated with first quintile of TSH using the third as the reference; IMT was independently associated with subclinical hypothyroidism, and cf-PWV was not associated with subclinical thyroid diseases
78

Estimation du mouvement de la paroi carotidienne en imagerie ultrasonore par une approche de marquage ultrasonore / Motion estimation of the carotid wall in ultrasound imaging using transverses oscillations

Salles, Sébastien 02 October 2015 (has links)
Ce travail de thèse est axé sur le domaine du traitement d’images biomédicales. L’objectif de notre étude est l’estimation des paramètres traduisant les propriétés mécaniques de l’artère carotide in vivo en imagerie échographique, dans une optique de détection précoce des pathologies cardiovasculaires. L’étude des comportements dynamiques de l’artère pour le dépistage précoce de l’athérosclérose constitue à ce jour une piste privilégiée. Cependant, malgré les avancées récentes, l’estimation du mouvement de la paroi carotidienne reste toujours difficile, notamment dans la direction longitudinale (direction parallèle au vaisseau). L’élaboration d’une méthode innovante permettant d’étudier le mouvement de la paroi carotidienne constitue la principale motivation de ce travail de thèse. Les trois contributions principales proposées dans ce travail sont i) le développement, la validation, et l’évaluation clinique d’une méthode originale d’estimation de mouvement 2D adaptée au mouvement de la paroi carotidienne, ii) la validation en simulation, et expérimentale de l’extension à la 3D de la méthode d’estimation proposée, et iii) l’évaluation expérimentale de la méthode proposée, en imagerie ultrasonore ultra-rapide, dans le cadre de l’estimation locale de la vitesse de l’onde de pouls. Nous proposons une méthode d’estimation de mouvement combinant un marquage ultrasonore dans la direction latérale, et un estimateur de mouvement basé sur la phase des images ultrasonores. Le marquage ultrasonore est réalisé par l’intermédiaire d’oscillations transverses. Nous proposons deux approches différentes pour introduire ces oscillations transverses, une approche classique utilisant une fonction de pondération spécifique, et une approche originale par filtrage permettant de contrôler de manière optimale leurs formations. L’estimateur de mouvement proposé utilise les phases analytiques des images radiofréquences, extraites par l’approche de Hahn. Ce travail de thèse montre que la méthode proposée permet une estimation de mouvement plus précise dans la direction longitudinale, et plus généralement dans les directions perpendiculaires au faisceau ultrasonore, que celle obtenue avec d’autres méthodes plus traditionnelles. De plus, l’évaluation expérimentale de la méthode sur des séquences d’images ultrasonores ultra-rapides issues de fantômes de carotide, a permis l’estimation locale de la vitesse de propagation de l’onde de pouls, la mise en évidence de la propagation d’un mouvement longitudinal et enfin l’estimation du module de Young des vaisseaux. / This work focuses on the processing of biomedical images. The aim of our study is to estimate the mechanical properties of the carotid artery in vivo using ultrasound imaging, in order to detect cardiovascular diseases at an early stage. Over the last decade, researchers have shown interest in studying artery wall motion, especially the motion of the carotid intima-media complex in order to demonstrate its significance as a marker of Atherosclerosis. However, despite recent progress, motion estimation of the carotid wall is still difficult, particularly in the longitudinal direction (direction parallel to the probe). The development of an innovative method for studying the movement of the carotid artery wall is the main motivation of this thesis. The three main contributions proposed in this work are i) the development, the validation, and the clinical evaluation of a novel method for 2D motion estimation of the carotid wall, ii) the development, the simulation and the experimental validation of the 3D extension of the estimation method proposed, and iii) the experimental evaluation of the 2D proposed method in ultra-fast imaging, for the estimation of the local pulse wave velocity. We propose a motion estimation method combining tagging of the ultrasound images, and a motion estimator based on the phase of the ultrasound images. The ultrasonic tagging is produced by means of transverse oscillations. We present two different approaches to introduce these transverses oscillations, a classic approach using a specific apodization function and a new approach based on filtering. The proposed motion estimator uses the 2D analytical phase of RF images using the Hahn approach. This thesis work shows that, compared with conventional methods, the proposed approach provides more accurate motion estimation in the longitudinal direction, and more generally in directions perpendicular to the beam axis. Also, the experimental evaluation of our method on ultra-fast images sequences from carotid phantom was used to validate our method regarding the estimation of the pulse wave velocity, the Young’s modulus of the vessels wall, and the propagation of a longitudinal movement.
79

Cardiovascular risk in ageing men of different ethnicities : inter-relationships between imaging and endocrine markers

Rezailashkajani, Mohammadreza January 2012 (has links)
Cardiovascular disease varies by ethnicity in the UK. South Asians (SA) have higher coronary heart disease (CHD) and diabetes prevalence, while African-Caribbeans (AfC) have greater stroke, but intriguingly lower CHD rates despite higher blood pressures and diabetes risk than Europeans. Conventional risk factors do not fully explain such differences. This cross-sectional study tested the hypothesis that the hormones, vitamin D measured as 25(OH)D and aldosterone, would be independently associated with intermediate cardiovascular outcome markers in these ethnic groups. Community-dwelling men 40-80 years old (AfC: n=67, 55±10yr; SA: n=68, 55±10yr; European: n=63, 57±8yr) were sampled from Greater Manchester’s multi-ethnic population. The intermediate markers examined were aortic pulse wave velocity (aPWV), left ventricular (LV) mass and function, and carotid intima media thickness (CIMT), measured non-invasively by ultrasound, and hemodynamic profiling methods (the Arteriograph) in the total sample and by magnetic resonance imaging (MRI) in a subsample of 50. Adjusted for age, systolic blood pressure and diabetes, mean(SE) aPWV by the Arteriograph, was 0.5(0.2) m/s higher in SA than AfC and Europeans (p=0.01), which paralleled known cross-ethnic CHD risk differences in the UK. By MRI, aPWV along the descending aorta in SA was 0.7(0.3) and 0.8(0.3) m/s higher than that in AfC and Europeans, but aPWV along the aortic arch was not significantly different. Unlike aldosterone, 25(OH)D was independently and inversely correlated with aPWV (unstandardised B(SE)=-0.013[0.004] m/s, p<0.001), and partly explained the ethnic variation in aPWV. Similar inverse correlations were found between 25(OH)D and LV concentricity measured by echocardiography and MRI. Compared to Europeans, SA and AfC, had 21(3) and 14(3) nmol/L lower mean(SE) 25(OH)D, respectively (p<0.01). Mean(SE) of relative wall thickness, an index of LV concentricity by echocardiography, was 0.05(0.01) higher in SA and AfC than Europeans. Lower 25(OH)D levels were also associated with higher myocardial deformation rates measured by MRI myocardial tagging (n=50), supporting previous animal experimental evidence. A one standard deviation (SD) decrease in 25(OH)D was associated with a 0.38 SD increase in absolute systolic strain rate (p=0.003) and 0.22 SD rise in diastolic strain rate (p=0.04). Right and left CIMT showed different relations with 25(OH)D and aldosterone. Left-right CIMT differences varied by ethnicity and were related to SA ethnicity and aldosterone levels. Two related technical studies investigated the relatively new method of hemodynamic profiling, the Arteriograph, used here. The results suggested a standardisation method of aortic length estimation for purely central aPWV, which significantly improved aPWV agreement between the Arteriograph and MRI (reference method here), and was used for calibrating the Arteriograph aPWV in the above-mentioned results for the total sample. Future well-designed trials are necessary to investigate any cause-effect relationship between vitamin D deficiency and the unfavourable cardiovascular intermediate outcomes found here in a cross-sectional design and multi-ethnic background.

Page generated in 0.1162 seconds