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Övervikt och fetma hos barn och ungdomar har blivit allt mer förekommande och prevalensen ökar dramatiskt över hela världen. Sedan raffinerade kolhydrater introducerades har även kariessjukdomen fått större utbredning. Då det finns gemensamma bakomliggande faktorer som påverkar både vikt och kariesprevalens vill vi i vår litteraturstudie undersöka om det finns något samband mellan body mass index (BMI) och kariesprevalens för barn och ungdomar. Efter sökningar i den medicinska databasen PubMed på artiklar från de senaste 5 åren fann vi oeniga resultat med jämn fördelning. Resultatet av litteraturstudien är att två av de undersökta studierna tyder på att det inte finns något samband mellan BMI och kariesprevalens, lika många anser att det finns en svag eller möjlig association, medan två studier ansåg att det fanns ett signifikant samband. Majoriteten av de undersökta studierna kan alltså inte se något signifikant samband mellan BMI och kariesprevalens. För att säkerställa ett samband eller ej krävs fler studier och en djupare analys av tillförlitligheten i respektive studie.

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

Objetivos: Avaliar a composição corporal através da medida das dobras cutâneas (DC) intra e inter observador em mulheres na fase reprodutiva. Estimar a confiabilidade de dois protocolos de medidas de dobras cutâneas com o método Absorciometria Radiológica de Dupla Energia (DEXA). Métodos: A amostra foi composta por 90 mulheres com faixa etária de 18 a 37 anos, com Índice de Massa Corporal entre 18 e <= 39,9 Kg/m². A reprodutibilidade dos métodos foram avaliados pelos coeficientes de correlação de concordância (CCC) e coeficiente de Saint Laurent e pelos limites de concordância e gráficos de Bland-Altman. Resultados: A comparação intra observador foi excelente (CCC = 0,99) para os valores das medidas de DC tricipital, supraíliaca, coxa, soma das dobras e percentual de gordura. O mesmo ocorreu na comparação inter observador (CCC = 0,99). As medidas das DC tricipital foram as que apresentaram maior CCC (0,98), seguido da medida da coxa (0,90), e a medida da DC da suprailíaca foi a menor (0,89). A soma das DC e o percentual de gordura tiveram valores de 0,95. Já os protocolos de medidas de DC comparados entre si e com o padrão ouro DEXA, obtiveram valores de concordância baixa (0,35). Conclusões: Nossos achados mostraram que a comparação intra e inter observador foi satisfatória, contribuindo para a reprodutibilidade das medidas de DC. Os protocolos de avaliação das DC não tiveram concordância quando comparados com a DEXA / Objectives: Assessing body composition by measuring the intra and inter observer skin folds in women in the reproductive phase and estimate the reliability of two protocols skinfold measures with radiographic absorptiometry method of dual energy absorptiometry (DEXA). Methods: The sample consisted of 170 women aged 18-37 years with body mass index between 18 and <= 39.9 kg / m². The reproducibility of methods and skinfold thickness were evaluated by the coefficient of concordance correlation (CCC) and coefficient of Saint Laurent and the limits of agreement and Bland-Altman. Results: Comparison intra observer was excellent with the same values of the CCC (0.99) for the measurements of skinfold thickness of the triceps, suprailiac, thigh and fat percentage. The same occurred in the comparison inter observer (CCC = 0.99). The measures of skinfold thickness of the triceps showed the greatest CCC (0.98), followed by thigh (0.90), and the suprailiac was the lowest (0.89). The sum of the measurements of skinfold thickness and the percentage of fat had CCC values of 0.95. Already the reliability of two protocols skinfold thickness measures compared with the gold standard DEXA method was low (CCC = 0.35). Conclusions: Our findings showed that compared intra and inter observer was satisfactory, contributing to the reproducibility of skin folds. Assessment protocols skinfold did not have agreement when compared with DEXA

Ένα από τα βασικά χαρακτηριστικά της ομόζυγης β-θαλασσαιμίας είναι η οστεοπάθεια, η οποία αποτελεί μία πολυπαραγοντική διαταραχή, που δεν έχει πλήρως διευκρινισθεί. Μελετήσαμε τους οσφυϊκούς σπονδύλους 48 ασθενών με τις μεθόδους Dual-Energy X-ray Absorptiometry (DXA) και Quantitative Computed Tomography (QCT), και εστιάσαμε στις δομικές οστικές ιδιότητες, όπως προσδιορίζονται από την υψηλής ευκρίνειας Υπολογιστική τομογραφία (HRCT). Οι τιμές της οστικής πυκνότητας (BMD values) εκφράσθηκαν ως Z-scores και τα αποτελέσματα συσχετίσθηκαν. Εκτιμήθηκε η επίδραση της ηλικίας, του φύλου, του τύπου της θαλασσαιμίας και των ορμονικών παραγόντων στις τιμές ΒΜD. Αξιολογήσαμε, με βάση την HRCT, την ακεραιότητα του φλοιού και τον αριθμό και πάχος των δοκίδων της σπογγώδους ουσίας. Με βάση τον αριθμό των δοκίδων ταξινομήσαμε τους ασθενείς σε κλίμακα τριών βαθμίδων. Τα αποτελέσματά μας έδειξαν ότι ο συνολικός επιπολασμός της οστεοπόρωσης με την μέθοδο DXA ήταν 44 % και με την QCT 6 %. Και οι δύο μέθοδοι έδειξαν μία αρνητική συσχέτιση μεταξύ της ηλικίας και της BMD, ενώ οι ορμονικοί παράγοντες παρουσίασαν συσχετίσεις τόσο με τις μετρήσεις της QCT όσο και με τις αντίστοιχες της DXA. Ο συντελεστής συσχέτισης μεταξύ της BMD της DXA και της σπογγώδους BMD της QCT ήταν 0,545 (p<0,001) ενώ η αντίστοιχη τιμή για τα Ζ-scores ήταν 0,491 (p<0,001). Η ομαδοποίηση των ασθενών σε φυσιολογικούς, οστεοπενικούς και οστεοπορωτικούς, με βάση το Ζ της QCT, ήταν σε καλύτερη συμφωνία με την ταξινόμηση με βάση τον αριθμό των δοκίδων (K=0,209, p=0,053), σε σύγκριση με την ομαδοποίηση σύμφωνα με το Ζ της μεθόδου DXA (K=0,145, p=0,120). Η εκτίμηση του φλοιού με την HRCT έδειξε διακοπές στη συνέχειά του σε 15 ασθενείς. Και οι δύο μέθοδοι δείχνουν μία επιδείνωση της οστεοπόρωσης με την πρόοδο της ηλικίας. Η ανεπάρκεια των ορμονών συσχετίζεται με την θαλασσαιμική οστεοπόρωση, ενώ η οτπική εκτίμηση του φλοιώδους οστού δείχνει ότι οι ενδιάμεσου τύπου θαλασσαιμικοί πάσχουν σε μεγαλύτερο βαθμό από τους ασθενείς με μείζονα μορφή θαλασσαιμίας. Με τον αριθμό των δοκίδων ως δείκτη οστεοπόρωσης, φαίνεται ότι η QCT μπορεί να εκτιμήσει την οστεοπάθεια καλύτερα από την DXA. Δεδομένου ότι η QCT έχει την ικανότητα να μετρήσει την οστική πυκνότητα του σπογγώδους και φλοιώδους οστού, ξεχωριστά, μπορεί να παρέχει πρώιμη ένδειξη του ποιο από τα δύο μεταβάλλεται πιο γρήγορα και σε τι βαθμό. - / Osteopathy, as a major feature of homozygous beta-thalassaemia, is a multifactorial disorder, not fully understood. We studied the lumbar vertebrae of 48 patients using Dual-Energy X-ray Absorptiometry (DXA) and Quantitative Computed Tomography (QCT), and we focused on structural properties, assessed by High Resolution Computed Tomography (HRCT). Bone Mineral Density (BMD) values were expressed as Z scores and the results were correlated. The effect of age, sex, type of thalassaemia and hormonal factors on BMD was assessed. We estimated, with HRCT, the cortex integrity and the number and thickness of trabeculae; the latter were classified to a three-grade scale. Our results showed the overall prevalence of osteoporosis to be 44 % with DXA and 6 % with QCT. Both techniques revealed an inverse correlation between age and BMD, whereas hormonal factors demonstrated associations with QCT and DXA measurements. The correlation coefficient between DXA’s BMD and QCT’s trabecular BMD was 0.545 (p<0.001) whereas the corresponding value for Z scores was r=0.491 (p<0.001). The classification of the patients into normal, osteopenic and osteoporotic categories, using QCT’s Z, was in better agreement with the assignment based on trabecular number (K=0.209, p=0.053) than the classification using DXA’s Z (K=0.145, p=0.120). Cortex evaluation by HRCT showed discontinuity in 15 patients. Both methods indicate a progression of osteoporosis with age. Hormonal deficiency is associated with thalassaemic osteoporosis whereas the visual estimation of cortex indicate that TI could be more affected than TM. Using the trabecular number as an indicator of osteoporosis, it seems that QCT may evaluate osteopathy better than DXA. Since the former has the ability to measure trabecular and cortical BMD separately, it could give early indication of which changes more rapidly and to what degree.

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

Cardiovascular disease (CVD) is one of the major health issues of our time. The prevalence of CVD is increasing, both in industrialized and in developing countries, and causes suffering and a decreased quality of life for millions of people worldwide. CVD can have multiple etiologies, but the main underlying cause is atherosclerosis, which causes blood clot formation and obstructs vital arteries. Multiple risk factors of atherosclerosis have been identified, and body fatness is one of the most important ones.  The main aims of this thesis were to investigate the relation between body fatness and: CVD risk factors (paper I), incident stroke (paper II), and overall mortality (paper III). The results showed that abdominal obesity is strongly associated with both CVD risk factors and stroke incidence (papers I-II). The results also suggested that a substantial part of the association between increased body fat and stroke can be explained by an increase in traditional stroke risk factors associated with increased body fat (paper II). A gynoid fat distribution, with a high share of fat located around the hip, is, on the other hand, associated with lower risk factor levels in both men and women, and with a decreased risk of stroke in women (papers I-II). This illustrates the importance of assessing the overall distribution of body fat rather, than solely focusing on total body fatness. In elderly women, total body fat was found to be associated with increased survival, while abdominal fat moderately increased mortality risk (paper III). Lean mass (fat-free mass) was strongly associated with increased survival among elderly men and women (paper III). Erythrocyte sedimentation rate (ESR) is an indicator of inflammation and, possibly, an indicator of atherosclerotic disease. In paper IV, the relationship between ESR in young adulthood and the later risk of myocardial infarction (MI) was studied. Results showed that higher levels of ESR were associated with a higher MI risk, in a dose-responsive manner, and was independent of other well-established risk factors. In summary, both total and regional fat distribution are associated with CVD risk factors and stroke, but do not seem to correspond to an increase in mortality risk among the elderly. Also, inflammation, detected as an increase in ESR, is associated with long term MI risk in young men.

In this thesis a method was developed to reconstruct both the 3D shape and the BMD distribution of bone structures from Dual-energy X-ray Absorptiometry (DXA) images. The method incorporates a statistical model built from a large dataset of Quantitative Computed Tomography (QCT) scans together with a 3D-2D intensity based registration process. The method was evaluated for its ability to reconstruct the proximal femur from a single DXA image. The resulting parameters of the reconstructions were subsequently evaluated for their hip fracture discrimination ability. The reconstruction method was finally extended to the reconstruction of the lumbar vertebrae from anteroposterior and lateral DXA, thereby incorporating a multi-object and multi-view approach. These techniques can potentially improve the fracture risk estimation accuracy over current clinical practice. / En esta tesis se desarrolló un método para reconstruir tanto la forma 3D de estructuras óseas como la distribución de la DMO a partir de una sola imagen de DXA. El método incorpora un modelo estadístico construido a partir de una gran base de datos de QCT junto con una técnica de registro 3D-2D basada en intensidades. Se ha evaluado la capacidad del método para reconstruir la parte proximal del fémur a partir de una imagen DXA. Los parámetros resultantes de las reconstrucciones fueron evaluados posteriormente por su capacidad en discriminar una fractura de cadera. Por fin, se extendió el método a la reconstrucción de las vértebras lumbares a partir de DXA anteroposterior y lateral incorporando así un enfoque multi-objeto y multi-vista. Estos técnicas pueden potencialmente mejorar la precisión en la estimación del riesgo de fractura respecto a la estimación que ofrece la práctica clínica actual.

Este trabalho teve como objetivo verificar se a técnica de impedância bioelétrica (IB) identifica as modificações da composição corporal em mulheres no período pós-parto. Participaram do estudo 47 mulheres (&#8805; 18 anos), nas quais foram avaliadas massa livre de gordura (MLG), massa gorda (MG) e percentual de gordura corporal (%GC) pelos equipamentos IB_Tanita BC 533; IB_RJL 101 e por absorciometria de raio X de dupla energia (DXA). Todas as avaliações foram feitas no mesmo dia. Posteriormente, as mulheres foram categorizadas em dois grupos: com perda ponderal (n= 24) e com ganho ponderal (n= 22). Os valores médios das alterações da composição corporal (CC), foram comparados intra-métodos e em relação ao método padrão-ouro (DXA) através de teste T-pareado. A concordância entre as diferenças das alterações da CC obtidas pelas IB e DXA foi avaliada pelo método de Bland & Altman e pelo coeficiente de correlação intraclasse (CCI). A média &#61617; desvio padrão de idade foi de 26,7 &#61617; 5,2 anos e o tempo médio da captação no pós-parto para a primeira avaliação foi de 2,6 &#61617; 2,0 meses e 8,0 &#61617; 2,7 meses para a segunda avaliação. A média de massa corporal (MC) foi de 74,6 &#61617; 11,4 kg na primeira avaliação e 75,1 &#61617; 12,6 kg na segunda avaliação, correspondendo a um valor de índice de massa corporal (IMC) de 28,8 &#61617; 4,0 kg/m2 e 29,0 &#61617; 4,6 kg/m2, respectivamente. O %GC medido pela DXA foi de 40,1 &#61617; 4,9 % para a primeira avaliação e de 41,0 &#61617; 5,2 %, para a segunda avaliação, representando uma MG de 30,2 &#61617; 6,6 kg e de 30,9 &#61617; 8,0 kg, respectivamente. Ambas as IB subestimaram a alteração do % GC (-0,7 % para IB_Tanita e -1,1% para IB_RJL) e MG (-0,6 kg para IB_Tanita e -1,0 kg IB_RJL) em relação ao DXA. Por sua vez, as alterações de MLG foram superestimadas 0,8 kg pela IB_Tanita e 1,0 kg IB_RJL. Houve boa concordância (CCI &#8805; 0,75) entre as alterações identificadas para MG pela IB_Tanita e por DXA e satisfatória pela IB_RJL. Dessa forma o presente estudo verificou um desempenho satisfatório da técnica de IB em identificar as alterações da MG gorda e que a IB_Tanita mostrou-se melhor que a IB_RJL na estimativa da alteração desse componente corporal nesse grupo de mulheres pós-parto. / The aim of the present study is to assure that the measurement of the bioelectrical impedance (IB) identifies the changes in the body composition of postpartum women. Forty-seven women (&#8805; 18 years of age) were enrolled in the study. Body composition (BC) - fat free mass (FFM), fat mass (FM) and percentage body fat (%BF) - was obtained by two IB devices (Tanita BC 533 and RJL 101) and DXA. All measurements were performed at the same day in two different postpartum moments. The women were categorized in two groups: with weight loss (WWL, n= 24) and with weight gain (WWG, n= 22). Pair T-test was used to compare mean difference values within methods and DXA. Bland & Altman plots and intraclass correlation coefficients (ICC) were used to evaluate the agreement between body composition changes obtained by both IB and DXA. The first and second visits for BC measurements occurred 2,6 &#61617; 2,0 months e 8,0 &#61617; 2,7 months after delivery, respectively. Mean ( SD) age was 26.7 &#61617; 5.2 years and body mass was 74.6 &#61617; 11.4 kg at the first visit and 75.1 &#61617; 12.6 kg at the second visit. Women were overweight in both visits (BMI= 28.8 &#61617; 4,0kg/m2 e 29.0 &#61617; 4.6 kg/m2). % BF measured by DXA at the first visit was 40.1 &#61617; 4.9% and at the second visit was 41.0 &#61617; 5.2% yielding on average a FM of 30.2 &#61617; 6,6 kg and 30,9 &#61617; 8,0 kg, respectively.. IB_Tantia yelded lower mean values for FFM and FM compare to DXA mean values, except for %BF. Both IB underestimated %BF (-0.7% for Tanita and -1.1% for RJL) and FM changes (-0.6 kg for Tanita and -1.0 for RJL) compared to DXA changes. On the other hand FFM changes were overestimated by Tanita (0,8 kg) and RJL (1,0 kg). There was a good agreement (CCI &#8805; 0.75) between FM changes measured by IB_Tanita and DXA and a fair agreement for IB_RJL. Therefore the IB technique was able to identified FM changes, and IB_Tanita showed a better performance than IB_RJL on the estimation of FM changes in these postpartum women.