Die Dualenergie-Röntgenabsorptiometrie (DEXA, Dual Energy X-Ray Absorptiometry) ist ein in der Humanmedizin und Teilen der Veterinärmedizin etabliertes Verfahren zur Untersuchung der Knochenmineraldichte, des Knochenmineralgehaltes und der Körperzusammensetzung. Für das Pferd existieren bisher lediglich vereinzelte Studien zur Untersuchung des Knochens mittels der DEXA-Methode, welche allesamt auf nur sehr geringen Versuchstierzahlen beruhen. Ziel dieser Arbeit war es daher die DEXA-Methode für die Untersuchung am Pferd zu validieren. Hierfür wurden die Röhrbeine von 103 Schlachtpferden mittels des Densitometers PIXI LUNAR®, welches aus der Humanmedizin stammt und dort zur Untersuchung des Unterarmes dient, untersucht und die densitometrische Knochenmineraldichte (BMD) und der densitometrische Knochenmineralstoffgehalt (BMC) ermittelt. Als Messpunkt wurde standar-disiert die Mitte zwischen der Basis und dem Caput des Os metacarpale tertium bzw. des Os metatarsale tertium gewählt. Im Anschluss an die densitometrische Messung wurde als Referenzverfahren eine chemische Analyse durchgeführt, in welcher der Rohasche- sowie der Calcium- Phosphor- und Magnesiumgehalt der Röhrbeine bestimmt wurden. Die Angabe der Ergebnisse erfolgt als Median und 25-/75-Perzentil. Der Rohaschegehalt lag im Mittel über alle Röhrbeine bei 698 (69,1 - 70,3) g/kg TS. Für die Mineralstoffe konnten folgende Gehalte ermittelt werden: Calcium 265 (259 - 272) g/kg TS, Phosphor 123 (121 - 126) g/kg TS und Magnesium 2,40 (2,19 - 2,66) g/kg TS. Das Calcium-Phosphor-Verhältnis lag in einem Bereich von 2,14 - 2,18. Die Resultate der DEXA-Methode werden neben dem Mineralstoffgehalt auch vom Knochenumfang beeinflusst, so dass die folgenden Ergebnisse für die Vorder- und Hintergliedmaße (VGM, HGM) separat dargestellt werden: BMD: VGM 3,22 (2,80 - 3,65) g/cm², HGM 4,21 (3,76 - 4,65) g/cm²; BMC: VGM 26,5 (22,8 - 30,1) g, HGM 32,9 (29,0 - 36,3) g. Im Rahmen dieser Arbeit wurden Reproduzierbarkeitsstudien durchgeführt, bei denen für die BMD bei der Reproduzierbarkeit ohne Reposition Abweichungen in einem Bereich von 1,06 - 1,85 % und mit Reposition in einem Bereich von 3,51 - 4,48 % gefunden wurden. Für die BMC lag die Abweichung für die Reproduzierbarkeit ohne Reposition in einem Bereich von 1,28 - 2,79 % und mit Reposition schwankte sie zwischen 3,38 und 3,94 %. Um für den Einsatz der DEXA-Methode bei Verlaufsuntersuchungen den Einfluss der exakten Messlokalisation zu eruieren, wurden Messungen in einem Abstand von ein, zwei und drei Zentimetern proximal und distal des ursprünglichen Messpunktes vorgenommen. Die Ergeb-nisse dieser Studie wichen für die BMD um 3,53 - 9,16 % und für den BMC um 4,21 - 12,5 % von den Ergebnissen des zentralen Messpunktes in der Mitte der Diaphyse ab. Diese Abweichung liegt innerhalb der 25-/75-Perzentile der Messergebnisse des zentralen Messpunktes. Die Ergebnisse der vorliegenden Studie führen zu dem Schluss, dass es möglich ist die Knochenmineraldichte und den Knochenmineralgehalt des Röhrbeines des Pferdes mittels der DEXA-Methode zu ermitteln. Die guten Ergebnisse der Reproduzierbarkeitsstudien und der Abstandsmessungen vom zentralen Messpunkt legen die Durchführbarkeit am stehenden, sedierten Pferd nahe. Bei der DEXA-Methode wird ein Knochenabschnitt mit einem sehr hohen Kortikalisanteil erfasst, welcher auf Einflüsse, wie beispielsweise Training oder Ruhigstellung mit einer Veränderung des Knochenumfanges bei gleichbleibenden Mineralstoffkonzentrationen reagiert. Diese Eigenschaft führt zu einem geringen Zusammenhang zwischen der DEXA-Methode und der chemischen Analyse, so dass sich die Ergebnisse der beiden Messverfahren zwar gut in den Kontext anderer Studien einfügen, der direkte Vergleich der beiden Methoden jedoch nicht möglich ist. / DXA (dual energy X-ray absorptiometry) is an established method for the measurement of bone mineral density (BMD), bone mineral content (BMC) and whole body composition in human and partly in veterinary medicine. However, there are only a small number of studies that examine the bone in horses using DXA. All these studies are based on small samples. Therefore, the objective of this study was to validate the use of DXA for the measurement of BMD and BMC in the horse. In total the cannons of 103 horses were scanned ex vivo, using the PIXI LUNAR® densitometer. In human medicine this densitometer is used for the exami-nation of the forearm. The measuring point was the exact middle between basis and caput of the third metacarpal/metatarsal bone. In a second step the DXA measurements were complemented with a chemical analysis, analyzing the ash content, calcium, phosphorus and magnesium content of the bones. The results are presented as median and 25-/75-percentile. The average ash content of the cannon bones was 698 (691 - 703) g/kg DM. The average mineral content was measured in the following order: calcium 265 (259 - 272) g/kg DM, phosphorus 123 (121 - 126) g/kg DM und magnesium 2.44 (2.19 - 2.66) g/kg DM. The ratio of calcium to phosphorus ranged from 2.14 to 2.18. The DXA results are influenced not only by the bone´s mineral content, but also by its diameter. Because of this the results are separated into the results of the forelimb (fl) and the hindlimb (hl) which generates the following results: BMD: fl 3.22 (2.80 - 3.65) g/cm², hl 4.21 (3.76 - 4.65) g/cm²; BMC: fl 26.5 (22.8 - 30.1) g, hl 32.9 (29.0 - 36.3) g. Several robustness checks of the measurements were conducted. For the BMD measurements, the range of measurements diverged by 3.51-4.48 % for measurements with limb repositioning, and by 1.06-1.85 % for measurements without limb repositioning. For the BMC measurements, the range of measurements diverged by 3.38-3.94 % for measurements with limb repositioning, and by 1.28-2.79 for measurements without limb repositioning. To determine the importance of the exact bone position for follow-up investigations, measurements in a distance of one, two and three centimeters proximal and distal of the original measuring point were performed. The results of these measurements deviated from the result of the central measuring point at the centre of the diaphysis in a range of 3.53 – 9.16 % for BMD and a range of 4.21 – 12.5 % for BMC. This variation falls within the percentiles of the central measuring point. Overall, the results of this study indicate that DXA is useable for determining BMD and BMC at the third metacarpal/metatarsal bone of the horse. The high reproducibility of the results and the distance measurements suggest that DXA is suitable for measurements at the standing, tranquilized horse. However, the cannon bone is a bone with a high content of cortical bone. This means that the diameter of the bone changes as a result of training or immobilization, while the BMD and BMC remain unchanged by such influence. This leads to a weak correlation between the results from the DXA and chemical analyses. Thus, while these two types of analysis fit well into the context of prior studies, a direct comparison between these measurements is not possible.

With the vast array of genetically altered (knockout) mice becoming available there is a need for quantitative, repeatable, and efficient methodologies to characterize the phenotypic consequences of knocking out specific genes. Since knockout animals often have the ability to compensate for a single missing gene, it is important to examine the structural, material and morphological properties to obtain a thorough understanding of the changes occurring. For this project, femurs of knockout mice were first scanned using microcomputed tomography (micro-CT) to obtain high-resolution images of the trabecular bone in the distal femur, as well as cortical bone in the mid-diaphysis. After scanning, the femurs were tested to destruction in four-point bending at the mid-diaphysis about the medial lateral axis of the femur. These methodologies allowed quantification of (1) morphologic properties such as bone volume fraction, trabecular properties and 2nd moment of the area (2) structural properties such as stiffness, maximum load at failure, and post yield deformation and (3) material properties such as bone mineral density, elastic modulus and yield strength. As part of two independent studies, two different knockout mice, cyclooxygenase-2 (COX-2 -/-) and Apolipoprotein E (APOE -/-), were examined for structure-function relationships using these methodologies. COX-2 knockout mice were found to have decreased mineral content in their femurs, and increased post yield deformation. APOE knockout mice at 10 weeks of age had decreased bone mass and structural properties. However, by 40 weeks of age APOE deficient mice caught up to and exceeded the structural properties and bone mass of their wild type counterparts.

No description available.

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

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.

Metabolic bone disease is a frequent complication of Crohn’s disease (CD) with the pathogenesis of reduced bone mass in CD reported to include body weight, disease severity, disease treatments and surgery, physical activity and nutritional status. To date, there have been no studies to examine the prevalence of osteopenia and osteoporosis in an Australian CD population. Similarly, the roles of disease state and treatment, lifestyle factors and the role of body composition in the development of bone loss in CD have not been examined in an Australian CD cohort to date. This thesis has sought, for the first time, to determine the prevalence and severity of bone loss in an Australian CD population and to examine the relationship between various clinical, genetic, lifestyle and treatment variables. The role of body composition in bone loss was assessed by close examination of the muscle-bone relationship by dual-energy X-ray absorptiometry (DXA) and the local muscle-bone unit by peripheral quantitative computed tomography (pQCT) so that informed targeted treatment strategies may be implemented. Study 1 assessed the prevalence of bone loss and both molecular and clinical risk factors for bone loss in a large Crohn’s disease population. Bone mineral density (BMD) data were combined with clinical information and correlated with single nucleotide polymorphisms within the TNF-α, interleukin-10, and NOD2/CARD15 genes. Study 2 examined the independent effects of body composition and muscle strength on regional and whole body BMD in a cohort of CD patients to determine their relative importance to bone strength in this population. Study 3 used pQCT for the first time in a CD population to assess the functional muscle-bone unit in order to determine if the high prevalence of low bone mass reported in CD patients is mediated by altered body composition, in particular muscle mass and strength. Study 1 revealed 45% of CD patients had previously been diagnosed with osteopenia and 18% with osteoporosis. Both the TNF-α “GT” haplotype and the -857 “CC” genotype showed strong associations with bone mineral density overall (p=0.003 and p=0.002, respectively). Body mass index (p=0.01) and previous bowel resection in females (p=0.03) were predictive of a higher spine bone density, whilst body mass index (p=0.003) and the effect of years since first bowel resection (p=0.02) remained independent predictors of proximal femur bone mineral density. When bone mineral density was assessed in Study 2, the prevalence of osteopenia and osteoporosis was 32% and 17%, respectively, with osteopenia more common at the hip and osteoporosis more common at the spine. In multiple regression analyses, appendicular muscle mass was an independent predictor of whole body and regional BMD while lean mass was an independent predictor at the hip. Neither grip strength nor fat mass were independently associated with BMD. Of the components of body composition, muscle mass was strongly associated with regional and whole body bone mineral density. When the muscle-bone unit was assessed using pQCT in Study 3 to further examine this relationship, CD patients demonstrated lower tibial shaft mass, tibial shaft cortical cross-sectional area, and proximal tibia bone mineral density than similarly aged healthy controls. CD subjects also had significantly lower areal bone mineral density by DXA than controls at the total body (P=0.038) and hip (P=0.019). There were no significant differences between groups for any of the muscle-bone indices assessed, such as bone mineral content/muscle cross-sectional area and bone cross sectional area / muscle strength. Together, these studies have demonstrated a high prevalence of metabolic bone disease in an Australian CD population. We were able to identify a novel protective association between a TNF-α haplotype and bone mineral density and also confirmed the importance of body mass index and intestinal resection on bone loss in this population. Furthermore, these studies indicated that lean mass, and more specifically muscle mass, was a significant independent predictor of regional and whole body BMD. Consequently, maintaining or increasing muscle mass in this patient population may have a positive effect on BMD and prevent the development of osteopenia and osteoporosis. Although only modest differences were found between CD patients and controls for areal BMD by DXA and some bone parameters by pQCT, there were no differences in indices of the muscle-bone unit. These results suggest that bone strength is adequate for muscle size and strength in our sample of male CD patients with well-controlled disease, inferring that no specific intervention is required to correct expected deficiencies in this relationship. Instead, an exercise training program introduced to this patient cohort should aim to maintain or increase bone mass through weight-bearing exercises as well as encourage the maintenance or increase in muscle mass.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Natural loss of estrogen occurring in menopausal process may contribute to various health problems many of them possibly related to oxidative stress. Decrease in circulating estrogen levels and increase in follicle stimulating hormone levels (FSH) in menopausal status are related with decrease in bone mineral density. Hormone replacement therapy (HRT) is the most common treatment to attenuate menopausal disturbances and strontium (Sr) and iron (Fe) have been suggested to influence to bone metabolism. The objectives of this study was to evaluate the influence of HRT on the activity of antioxidant enzymes (SOD, CAT, and GPx) and lipid peroxidation (TBARS) in menopausal women and to determine blood strontium and iron levels and their relationship with bone mineral density and biochemical parameters in pre and postmenopausal women with or without HRT. Blood antioxidant enzyme activities were determined in premenopausal (n=18) and in postmenopausal healthy women without (n=21) or with HRT (n=19) (mean ages: 47, 59, and 57, respectively). Whole blood Sr and Fe levels were determined by spectrometric methods (inductively coupled plasma mass spectrometry - ICP-MS and inductively coupled plasma optical emission spectrometry - ICP-OES, respectively) in premenopausal (n=17) and postmenopausal women without (n=20) or with HRT (n=19) (mean ages: 47, 60 and 57 years, respectively). Bone mineral density (BMD) was evaluated at the lumbar spine (BMD L1-L4) and femoral neck (BMD femur) by dual energy X-ray absorptiometry (DEXA). TBARS, CAT, and GPx activity were not significantly different among the groups of study. However, SOD activity was significantly lower in postmenopausal women without HRT (0.68±0.04 U/mg Hb) when compared both to premenopausal women (0.91±0.04 U/mg Hb) and to postmenopausal women with HRT (0.89±0.07 U/mg Hb). SOD activity was positively correlated to the duration of HRT in the postmenopausal groups (r=0.33, p<0.05). Blood Sr and Fe levels in premenopausal (33.66±3.57 µg L-1 and 502.09±19.90 mg L-1, respectively) and postmenopausal women without (31.47±2.58 µg L-1 and 523.65±9.91 mg L-1, respectively) or with HRT (29.74±3.02 µg L-1 and 540.30±20.24 mg L-1, respectively) were not significantly different among study groups. BMD L1-L4 and BMD femur were significantly higher in premenopausal women (1.05±0.23 and 0.84±0.02 g/cm2, respectively) when compared both to postmenopausal women without (0.90±0.37 and 0.75±0.02 g/cm2, respectively) and to postmenopausal women with HRT (0.94±0.04 and 0.74±0.02 g/cm2, respectively). However, BMD had no relationship with blood metal levels, but was negatively influenced by FSH levels (β=-0.47, p<0.01 for BMD L1-L4 and β=-0.42, p<0.01 for BMD femur) and age (r=-0.48, p<0.01 for BMD L1-L4 and r=-0.38, p<0.01 for BMD femur). We concluded that HRT antagonizes the decrease of SOD activity that occurs after menopause, suggesting that HRT may play a beneficial role in the protection against oxidative stress. It was also shown that the physiologic whole blood Sr and Fe levels had no significant effect in BMD or other biochemical parameters in pre and postmenopausal women. BMD decreased with the increased in FSH levels and with aging. / A redução natural nos níveis de estrogênio, que ocorre na menopausa pode contribuir para vários problemas de saúde muitos deles também possivelmente relacionados ao estresse oxidativo. A diminuição dos níveis circulantes de estrogênio e o aumento de hormônio folículo estimulante (FSH) em mulheres na menopausa estão sendo associados à perda óssea. A terapia de reposição hormonal (TRH) é o tratamento mais comum para atenuar os distúrbios menopáusicos e, as concentrações sanguíneas de estrôncio (Sr) e ferro (Fe) têm mostrado influenciar no metabolismo ósseo. Os objetivos deste estudo foram avaliar a influência da TRH na atividade de enzimas antioxidantes (SOD, CAT e GPx) e lipoperoxidação (TBARS); e determinar os níveis de Sr e Fe e sua relação com a densidade mineral óssea (DMO) e parâmetros bioquímicos em mulheres na pré e pós menopausa com e sem TRH. As atividades das enzimas antioxidantes foram determinadas no sangue total de mulheres na pré-menopausa (n= 18) e na pós-menopausa sem (n= 21) e com TRH (n= 19); a idade média dos grupos foi de 47, 59 e 57 anos, respectivamente. As concentrações de Sr e Fe foram avaliadas por espectrofotometria (espectrometria de massas com plasma acoplado indutivamente - ICP-MS e espectrometria de emissão óptica com plasma acoplado indutivamente - ICP-OES, respectivamente), no sangue de mulheres na pré-menopausa (n= 17) e na pós-menopausa sem (n= 20) e com TRH (n= 19), com idade média de 47, 60 e 57 anos, respectivamente. A DMO foi determinada na lombar (L1-L4) e no colo do fêmur por absorciometria de duplo feixe de raios-X (DEXA). Em nosso estudo TBARS, CAT e GPx não foram significativamente diferentes entre os grupos. No entanto, a atividade da SOD foi significativamente menor em mulheres na pós-menopausa sem TRH (0,68±0,04 U/mg Hb) quando comparado com os grupos pós-menopausa com TRH (0,89±0,07 U/mg Hb) e na pré-menopausa (0,91±0,04 U/mg Hb). A atividade da SOD também apresentou correlação positiva com o tempo de TRH (r=0,33; p<0,05) nas mulheres menopausadas. As concentrações de Sr e Fe não diferiram entre as mulheres não menopausadas (33,66±3,57 µg L-1 e 502,09±19,90 mg L-1, respectivamente) e aquelas na pós-menopausa sem (31,47±2,58 µg L-1 e 523,65±9,91 mg L-1, respectivamente) ou com TRH (29,74±3,02 µg L-1 e 540,30±20,24 mg L-1, respectivamente). A DMO da L1-L4 e fêmur foi maior nas mulheres que não estavam na menopausa (1,05±0,23 e 0,84±0,02 g/cm2, respectivamente) quando comparado com os grupos de mulheres na pós-menopausa sem (0,90±0,37 e 0,75±0,02 g/cm2, respectivamente) e com TRH (0,94±0,04 e 0,74±0,02 g/cm2, respectivamente). No entanto, a DMO não apresentou correlação com as concentrações de metais encontradas. A DMO foi negativamente influenciada pelos níveis de FSH (β=-0,47, p<0,01 para DMO L1-L4 e β=-0,42, p<0,01 para DMO fêmur), e pela idade (r=-0,48, p<0,01 para DMO L1-L4 e r=-0,38, p<0,01 para DMO fêmur). Concluiu-se que a TRH antagoniza a diminuição da atividade antioxidante da SOD que ocorre após a menopausa, sugerindo o papel protetor da terapia contra o estresse oxidativo. Também demonstramos que as concentrações sanguíneas de Sr e Fe encontradas não exerceram efeito significativo na DMO e outros parâmetros bioquímicos e não foram influenciadas pela menopausa ou pela TRH em mulheres na pré e pós-menopausa. A diminuição na DMO observada foi em decorrência do aumento nos níveis circulantes de FSH e do processo de envelhecimento.

No description available.

A Osteoporose é uma doença esquelética caracterizada pelo comprometimento da resistência óssea predispondo a um risco aumentado de fraturas em mulheres na pósmenopáusa e na população idosa. O processo de remodelamento ósseo é mediado pela atividade dos osteoblastos na formação e a atividade dos osteoclastos na reabsorção da matriz óssea. Entre os vários fatores que modulam o processo de ressorção óssea estão os hormônios esteróides sexuais. Desta forma, a diminuição dos estrogênios circulantes, como ocorre na menopausa e na Falência Ovariana Prematura (FOP) resulta em uma maior perda da massa óssea. A FOP é uma condição definida como a falência da função ovariana antes dos 40 anos de idade, causando amenorréia, hipogonadismo e níveis elevados de gonadotrofinas. Vários estudos têm sugerido que esta falência gonadal possa ser uma doença genética, sendo o gene do receptor do FSH (FSHR), considerado um dos principais genes candidatos. Entretanto faltam estudos consistentes capazes de avaliar a influência destas variantes genéticas sobre a densidade mineral óssea assim como o risco de osteoporose. Assim, estudou-se uma coorte de 32 mulheres com FOP acompanhadas na Unidade de Endocrinologia Ginecológica, Serviço de Endocrinologia do Hospital de Clínicas de Porto Alegre, com os objetivos de determinar a freqüência de alterações na DMO e analisar uma possível associação entre variáveis hormonais e densidade mineral óssea comparando-as com um grupo de referência composto por 80 mulheres, sendo 25 mulheres na pré-menopausa (PRE-M) e 55 mulheres na pós-menopausa (POS-M). Também foi pesquisado se a presença de polimorfismos do gene do receptor do FSH estava associada com alterações na densidade mineral óssea no grupo FOP. Variáveis clínicas e hormonais foram obtidas, assim como a densitometria óssea foi realizada em todas as pacientes de ambos grupos, porém a análise da freqüência das variantes Ala307Thr e Ser680Asn do exon 10 do gene do FSHR foi realizada somente das pacientes do grupo FOP. A densitometria óssea de cada paciente foi classificada como massa óssea normal ou baixa massa óssea (osteopenia ou osteoporose) pelos critérios da OMS. O IMC apresentou correlação positiva com a DMO do fêmur total (p<0.05). A freqüência de baixa massa óssea foi significativamente maior no grupo FOP do que no grupo POS-M (p=0,042). Entretanto, quando a análise foi controlada pelo uso ou não de terapia hormonal, os grupos não apresentaram diferença significativa. Identificou-se maior freqüência de baixa massa óssea em L1-L4 no grupo FOP (p<0,001) enquanto o grupo de referência POS-M apresentou maior freqüência de baixa massa óssea no fêmur total (p<0,001). Não houve associação entre as variantes Ala307Thr e Ser680Asn do gene do FSH e a densidade mineral óssea (DMO em g/cm2) em coluna ou fêmur total. Concluindo, o grupo de pacientes com FOP apresentou maior frequência de alteraçoes na DMO, em especial em coluna, quando comparado com o grupo de referência na pós-menopausa. Embora os polimorfismos estudados no exon 10 do gene do FSHR possam modificar a ação do FSH, estas variantes genéticas parecem não ter influência sobre a DMO das pacientes com FOP. Entretanto, estudos longitudinais são necessários para confirmar os resultados do presente estudo. / Osteoporosis is a skeletal disease characterized by impairment of bone strength predisposing to an increased risk of fractures in postmenopausal women and in the elderly population. The process of bone remodeling is mediated by the activity of osteoblasts in the formation and activity of osteoclasts in the resorption of bone matrix. One of the factors modulating bone resorption is sex steroid hormones. Thus, the decline of circulating estrogens, as occurs in menopause and in premature ovarian failure (POF) results in greater loss of bone mass, POF is a condition defined as the failure of ovarian function before the age of 40 years, causing amenorrhea, hypogonadism and high levels of gonadotropins. Several studies have suggested that this gonadal failure can be a genetic disease, and the gene of the FSH receptor (FSHR), is considered as one of the leading candidate genes. Nonetheless, there is lacking studies that could consistently assess the influence of these genetic variants on the bone mineral density and the risk of osteoporosis. Therefore, a cohort of 32 women presenting POF and being followed at the Gynecological Endocrinology Unit, Division of Endocrinology, Hospital de Clinicas de Porto Alegre, was studied, with the objectives of determining the frequency of changes on BMD and analyze a possible association between hormonal variables and BMD, compared to a reference group composed of 80 women, with 25 in pre-menopausal (PRE-M) and 55 women in post-menopausal (POS-M). There was also searched if the presence of FSH receptor polymorphisms was associated with changes in the in bone mineral density in the group of POF. Clinical and hormonal variables were obtained as well as bone densitometry was performed in all patients in both groups; however, the analysis of the frequency of Ala307Thr and Ser680Asn variants of exon 10 of the gene of FSHR was performed only in the group of POF. Bone densitometry of each patient was classified as normal bone mass or low bone mass (osteopenia or osteoporosis) by the WHO criteria. BMI showed a positive correlation with BMD of the total femur (p <0.05). The frequency of low bone mass was significantly higher in the group of POF patients than in the POS-M group (p = 0042). However, when the analysis was controlled by the use of hormonal therapy, the no statistical difference was observed. A higher frequency of low bone mass in L1-L4 was identified in the POF group (p <0001) while the reference group of POS-M showed higher frequency of low bone mass in the total femur (p <0001). There was no association between the Ala307Thr and Ser680Asn variants of the FSHR gene and bone mineral density (BMD in g/cm2) in L1-L4 or in femur total. In conclusion, POF group presented a higher frequency of changes on BMD, mainly in lumbar spine, when compared to the reference POS-M group. While the studied polymorphisms in the exon 10 of the FSHR gene may modify the FSH actions, these genetic variants appear to have no influence on BMD of these patients. However, longitudinal studies are needed to confirm the results of this study.

Made available in DSpace on 2015-07-22T20:49:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-24 / Introdução: O aumento da expectativa de vida em nossa população traz preocupações relacionadas a morbi-mortalidade decorrente das fraturas osteoporóticas. É consensual que a prática de atividade física orientada traz benefícios, aumentando as chances de um envelhecimento saudável. A cidade de São Caetano do Sul (SCS) possui o primeiro Índice de desenvolvimento humano (IDH) e possui a 2ª maior renda per capta de nosso país. Tivemos a possibilidade de utilizar os dados do Projeto Longitudinal de Envelhecimento e Aptidão Física de SCS, que consiste em avaliar e acompanhar munícipes de São Caetano do Sul com idade acima de 50 anos, quanto as variáveis de aptidão física, capacidade funcional, aspectos sociais, nutricionais e psicológicos, envolvidos estes na prática de atividades físicas, no mesmo local. Objetivos: verificar a associação entre a composição corporal, das variáveis de aptidão física e da capacidade funcional sobre a densidade mineral óssea em mulheres pós-menopausadas praticantes de atividade física. Desenho do Estudo: Corte transversal da coorte do Projeto Longitudinal de Envelhecimento e Aptidão Física de São Caetano do Sul. Local de realização: Centro Social e Recreacional da Terceira Idade “Dr. Moacyr Rodrigues”, localizado no município de São Caetano do Sul, São Paulo - SP, Brasil. Participantes: 117 mulheres com idade acima de 50 anos e média de 67,8 ± 7,0 anos. Participantes de um programa regular de atividades físicas com sessões de duas vezes semanais e duração de 50 minutos, por em média pelo menos 8,0 ± 6,8 anos. Métodos: Todas as mulheres da amostra responderam a uma anamnese em forma de entrevista e passaram por uma avaliação física e por exames clínicos. Avaliamos a composição corporal (a massa corporal, a estatura corporal total, calculamos o IMC, as circunferências corporais de braço contraído, de perna (panturrilha), de cintura e de quadril, calculamos a RCQ, a massa magra, a massa gorda e a densidade mineral óssea em diversos sítios). Verificamos as variáveis de aptidão física (a força de preensão manual, a força de membros superiores e a força de membros inferiores mediante dois diferentes testes) e na capacidade funcional(equilíbrio estático com controle visual), além de submetermos a amostra a testes bioquímicos (creatinina, cálcio total, paratormônio, TSH). Resultados: Encontramos uma prevalência de osteoporose bastante similar a encontrada em populações de outros países semelhantes quanto à etnia. A força de preensão manual foi a variável de melhor associação com a densidade mineral óssea de todos os sítios ósseos analisados. Quando propusemos o modelo de regressão linear múltipla, a massa magra juntamente com a força de preensão manual explicaram em 28% a DMO de colo de fêmur e 24% DMO de corpo total; enquanto que 21% da DMO de coluna lombar foi explicada pela força de preensão manual, a massa corporal e o equilíbrio estático com controle visual, sempre levando em consideração a correção pela idade cronológica e a idade de menopausa. Conclusões: A variável de melhor associação com os sítios da densidade mineral óssea foi a força de preensão manual e nos modelos múltiplos a massa magra e a força de preensão manual apresentaram melhor relação com a DMO de colo de fêmur e corpo total. Na DMO de coluna lombar (L1- L4) obtivemos associação das variáveis de força de preensão manual, a massa corporal e o equilíbrio estático com controle visual. Isto reforça a importância da melhoria e/ou da manutenção da força de muscular e da massa magra ao longo da vida, com o objetivo de contribuir para a autonomia e independência do indivíduo diante do processo de envelhecimento. / Introduction: The increase of life expectation in our population results in concerns related to the morbi-mortality due to the osteoporotic fractures. It is consensual that the practice of guided physical activity leads to benefits, increasing the chances of a healthy aging. The city of São Caetano do Sul (SCS), the first one in the Index of human development (IDH) in Brazil, presents the second larger income per capture of our country. We had the possibility to use the data of the Longitudinal Project of Aging and Physical fitness of SCS, that consists of evaluating and following citizens from São Caetano do Sul aged 50 an over, concerning functional capacity, as well as social, nutritional and psychological aspects related to the physical activity practice in the same. Objectives: to verify the association of body composition, physical fitness variables and functional capacity on bone mineral density in physically active postmenopausal women. Design: this study is a part of Longitudinal Project of Aging and Physical Fitness of São Caetano do Sul. Setting: the Social Center and Recreacional of the Third Age "Dr. Moacyr Rodrigues", located in the district of São Caetano do Sul, São Paulo - SP, Brazil. Participants: 117 women aging 50 years or more (average of 67,8 ± 7,0 years), participants of a regular physical activity program, in a 50-minute-session twice a week, with a mean of 8,0 ± 6,8 years of practice. Measurements: all the women of the sample were interviewed for an anamnesis and were submitted to a physical evaluation and clinical exams. We evaluated the body composition (body weight, total body stature, BMI, body circumferences of contracted arm, leg (calf), waist and hip, RCQ, lean mass, fat mass and bone mineral density in several sites). We verified the physical fitness variables (handgrip, strength of upper and lower limbs using two different tests) and a functional capacity (static balance with visual control). Besides we submitted the XXIII sample to biochemical analysis (creatinine, total calcium, PTH, TSH). Results: we found a prevalence of osteoporosis that was quite similar to the one seen in populations of other countries with similar ethnic characteristics. The handgrip strength was the variable that better associated with the bone mineral density of all analyzed bone sites. When the model of multiple lineal regression was proposed, it revealed that the lean mass together with the handgrip strength explained by 28% the BMD of femoral neck and 24% the BMD of total body; while the BMD of lumbar spine (L1-L4) was explained by 21% by the variables handgrip, body weigh and static balance all together, always taking into account the adjustment for chronologic and menopause age. Conclusion: the variable that best associated with the bone mineral density was the handgrip strength, and in the multiple regression models the lean mass and the handgrip strength presented a better association with BMD of femoral neck and total body. About the BMD of lumbar spine (L1 - L4) we found association of the variables handgrip, body weight and static balance, always taking into account the chronological and the menopause age. These data demonstrate, importance of improving and/or maintaining the muscle strength and the lean mass along life aiming to contribute for the individual's autonomy throughout the aging progress. / TEDE / BV UNIFESP: Teses e dissertações