The purpose of this thesis project was to determine the precision error of dual-energy x-ray absorptiometry (DXA) derived bone mineral density (BMD) at regions of interest (ROI) that are clinically relevant to persons with spinal cord injury (SCI), and secondarily to compare the precision error between a group of persons who are able-bodied and a group of persons with chronic SCI. Over 2 visits, four DXA scans at sites of the distal femur, proximal tibia, and calcaneus were completed in 10 persons who are able-bodied and 10 persons with chronic SCI. Using forearm sub region analysis, we measured the BMD and calculated the precision error for a total of 7 ROI at these sites. Despite a lower BMD at every ROI in the group of persons with chronic SCI compared to the group of persons who are able-bodied (range, 33 – 56%), the relative precision error was similar between groups. However, there was a trend for greater precision error in persons with SCI at a whole bone ROI of the distal femur (RMS-CV of 8.40% vs. 5.63%) and a ROI of the posterior calcaneus body (RMS-CV of 3.52% vs. 1.78%) when compared to persons who are able-bodied. Further, the ROI of the posterior calcaneus body appeared to have a lower precision error in persons who are able-bodied (RMS-CV, 1.78%) than the distal femur and proximal tibia (RMS-CV range 3.26 – 5.63%). The results from this study suggest that the precision error of DXA derived BMD is similar between persons with SCI and persons who are able-bodied, and that the posterior calcaneus body may be a more precise site than the distal femur and proximal tibia.

There is a pressing need for better assessment of bone strength as current clinical tools do not directly measure bone mechanical properties, but offer only surrogate measures of bone strength. We conducted an ex-vivo study of emu bones to examine how two investigative devices, hr-pQCT and MRTA, compare to current clinical tools (DXA and QUS) in predicting true bone mechanical properties. We found that hr-pQCT parameters were able to assess bone strength as well as DXA and better than QUS, while MRTA was able to predict bone strength well in low-density but not high-density bones. Our results suggest that both hr-pQCT, which has the unique ability to specifically assess the various determinants of bone strength, and MRTA, which measures a bone mechanical property (stiffness), have great potential for use as clinical tools that can assess various components of bone strength not measured by current devices.

Introdução: Irisina é uma adipocina / miocina, descrita pela primeira vez em 2012 e parece estar envolvida na termogênese do tecido adiposo e na homeostase metabólica. A síndrome dos ovários policísticos (PCOS) é reconhecida como um distúrbio endocrinológico prevalente em mulheres com idade reprodutiva, e está frequentemente associado à obesidade abdominal, resistência à insulina, dislipidemia e hipertensão arterial. Objetivos: Determinar os níveis circulantes de irisina numa amostra de mulheres com PCOS e controles ovulatórias não hirsutas e verificar se os níveis séricos de irisina estão associados com variáveis hormonais, metabólicas e de composição corporal nestas participantes. Métodos: Neste estudo caso-controle foram incluídas 49 mulheres com PCOS e 33 mulheres controles ovulatórias não-hirsutas com idade e índice de massa corporal (IMC) semelhantes. Variáveis demográficas, antropométricas, hormonais e metabólicas foram obtidas através de dados da história médica, exame físico e dosagens bioquímicas e hormonais convencionais. A composição corporal foi avaliada por absorciometria de raios-X de dupla energia (DXA). Os níveis séricos de irisina foram mensurados por um kit ELISA humano. Resultados: A pressão arterial sistólica, HOMA, testosterona total e índice de androgênios livres (IAL) foram significativamente maiores e a SHBG foi menor nas PCOS. Após a estratificação por IMC, massa gorda e razão massa gorda / massa magra foram menores em mulheres com peso normal do que em mulheres com sobrepeso / obesidade. O grupo PCOS com peso normal apresentou menos massa magra total do que o grupo PCOS com sobrepeso / obesidade e subgrupos controles. A proporção de massa magra apendicular / IMC foi significativamente maior nas controles de peso normal que em controles com sobrepeso / obesidade, mas os subgrupos de PCOS foram semelhantes entre si e com as controles de peso normal e obesas. Os níveis séricos de irisina foram significativamente maiores nas pacientes 8 PCOS com sobrepeso / obesidade em comparação com as controles de peso normal. A irisina circulante correlacionou-se positivamente com o HOMA. Observou-se também correlação positiva da irisina com massa magra total e razão massa gorda /massa magra em mulheres com PCOS, mesmo após ajuste para IAL. Conclusão: Os dados do presente estudo sugerem uma associação de irisina com variáveis de composição corporal. / Introduction: Irisin is an adipokine / myokine, first described in 2012 and appears to be involved in adipose tissue thermogenesis and metabolic homeostasis. The polycystic ovary syndrome (PCOS) is recognized as a frequent endocrine disorder in women of reproductive age, and is often associated with abdominal obesity, insulin resistance, dyslipidemia, and hypertension. Objectives: To determine the circulating levels of irisin in women with PCOS and non-hirsute ovulatory control women, and to evaluate whether serum irisin levels are associated with hormone, metabolic and body composition variables in these participants. Methods: In this case-control study, 49 women with PCOS and 33 nonhirsute ovulatory controls women with similar age and body mass index (BMI) were enrolled. Demographic, anthropometric, hormone and metabolic variables were assessed by medical history, physical examination and conventional biochemical and hormon determinations. Body composition was assessed by double-energy X-ray absorptiometry (DXA). Serum irisin levels were measured by a human ELISA kit. Results: Systolic blood pressure, HOMA, total testosterone and FAI were higher and SHBG was lower in PCOS. After stratification by BMI, fat mass and fat mass / lean mass ratio were lower in women of normal weight in overweight / obese women. The PCOS group at normal weight had less total lean mass than the overweight / obese PCOS group and control subgroups. The lean appendicular mass / BMI ratio was significantly higher in normal weight controls than in overweight / obese controls, but PCOS subgroups were similar between them and with normal and obese weight controls. Serum irisin levels were significantly higher in overweight / obese PCOS patients than in normal weight controls. Circulating irisin was positively correlated with HOMA. A positive correlation was also observed between irisin 10 and total lean mass and fat mass / lean mass ratio in women with PCOS, even when adjusted for FAI. Conclusion: Our data suggest an association of irisin and body composition variables.

Introdução: Irisina é uma adipocina / miocina, descrita pela primeira vez em 2012 e parece estar envolvida na termogênese do tecido adiposo e na homeostase metabólica. A síndrome dos ovários policísticos (PCOS) é reconhecida como um distúrbio endocrinológico prevalente em mulheres com idade reprodutiva, e está frequentemente associado à obesidade abdominal, resistência à insulina, dislipidemia e hipertensão arterial. Objetivos: Determinar os níveis circulantes de irisina numa amostra de mulheres com PCOS e controles ovulatórias não hirsutas e verificar se os níveis séricos de irisina estão associados com variáveis hormonais, metabólicas e de composição corporal nestas participantes. Métodos: Neste estudo caso-controle foram incluídas 49 mulheres com PCOS e 33 mulheres controles ovulatórias não-hirsutas com idade e índice de massa corporal (IMC) semelhantes. Variáveis demográficas, antropométricas, hormonais e metabólicas foram obtidas através de dados da história médica, exame físico e dosagens bioquímicas e hormonais convencionais. A composição corporal foi avaliada por absorciometria de raios-X de dupla energia (DXA). Os níveis séricos de irisina foram mensurados por um kit ELISA humano. Resultados: A pressão arterial sistólica, HOMA, testosterona total e índice de androgênios livres (IAL) foram significativamente maiores e a SHBG foi menor nas PCOS. Após a estratificação por IMC, massa gorda e razão massa gorda / massa magra foram menores em mulheres com peso normal do que em mulheres com sobrepeso / obesidade. O grupo PCOS com peso normal apresentou menos massa magra total do que o grupo PCOS com sobrepeso / obesidade e subgrupos controles. A proporção de massa magra apendicular / IMC foi significativamente maior nas controles de peso normal que em controles com sobrepeso / obesidade, mas os subgrupos de PCOS foram semelhantes entre si e com as controles de peso normal e obesas. Os níveis séricos de irisina foram significativamente maiores nas pacientes 8 PCOS com sobrepeso / obesidade em comparação com as controles de peso normal. A irisina circulante correlacionou-se positivamente com o HOMA. Observou-se também correlação positiva da irisina com massa magra total e razão massa gorda /massa magra em mulheres com PCOS, mesmo após ajuste para IAL. Conclusão: Os dados do presente estudo sugerem uma associação de irisina com variáveis de composição corporal. / Introduction: Irisin is an adipokine / myokine, first described in 2012 and appears to be involved in adipose tissue thermogenesis and metabolic homeostasis. The polycystic ovary syndrome (PCOS) is recognized as a frequent endocrine disorder in women of reproductive age, and is often associated with abdominal obesity, insulin resistance, dyslipidemia, and hypertension. Objectives: To determine the circulating levels of irisin in women with PCOS and non-hirsute ovulatory control women, and to evaluate whether serum irisin levels are associated with hormone, metabolic and body composition variables in these participants. Methods: In this case-control study, 49 women with PCOS and 33 nonhirsute ovulatory controls women with similar age and body mass index (BMI) were enrolled. Demographic, anthropometric, hormone and metabolic variables were assessed by medical history, physical examination and conventional biochemical and hormon determinations. Body composition was assessed by double-energy X-ray absorptiometry (DXA). Serum irisin levels were measured by a human ELISA kit. Results: Systolic blood pressure, HOMA, total testosterone and FAI were higher and SHBG was lower in PCOS. After stratification by BMI, fat mass and fat mass / lean mass ratio were lower in women of normal weight in overweight / obese women. The PCOS group at normal weight had less total lean mass than the overweight / obese PCOS group and control subgroups. The lean appendicular mass / BMI ratio was significantly higher in normal weight controls than in overweight / obese controls, but PCOS subgroups were similar between them and with normal and obese weight controls. Serum irisin levels were significantly higher in overweight / obese PCOS patients than in normal weight controls. Circulating irisin was positively correlated with HOMA. A positive correlation was also observed between irisin 10 and total lean mass and fat mass / lean mass ratio in women with PCOS, even when adjusted for FAI. Conclusion: Our data suggest an association of irisin and body composition variables.

Made available in DSpace on 2014-06-11T19:28:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-02-17Bitstream added on 2014-06-13T19:57:16Z : No. of bitstreams: 1 goncalves_d_me_arafo.pdf: 759726 bytes, checksum: bf87f7a2311ccd6bf0527eebd3af2f33 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente estudo teve como objetivo avaliar possíveis alterações na densidade mineral óssea mandibular e femoral decorrentes da deficiência de estrógeno promovida pela ooforectomia (OVX), e a influência dessas alterações sobre a doença periodontal induzida em ratas. Quarenta e oito ratas, Holtzman, com idade de 90 dias, foram distribuídas em 5 grupos: Grupo controle (n=9), Grupo 1- SHAM sem indução de doença periodontal (n=11), Grupo 2- SHAM com indução de doença periodontal (n=10), Grupo 3- OVX sem indução de doença periodontal (n=9) e Grupo 4- OVX com indução de doença periodontal (n=9). Nove animais foram sacrificados no dia zero; 18 foram submetidos à cirurgia de OVX e 21 à cirurgia simulada (SHAM). Para os animais pertencentes aos grupos 2 e 4, após um período de 120 dias, foram colocadas ligaduras de fio de algodão nos primeiros molares inferiores as quais permaneceram por um período de 30 dias. Finalizado o período de 5 meses, os animais foram mortos sendo removidos a mandíbula, o fêmur e o útero. Foram efetuadas medidas de BMD global e de sub-regiões, da mandíbula e do fêmur, assim determinadas: hemimandíbula: global; R1 - região do côndilo mandibular; R2 - bordo inferior do corpo mandibular e R3 - região incisal da mandíbula e para o fêmur: global; R1 - epífise distal; R2 - epífise proximal e R3 - diáfise. Foram avaliadas, por meio de radiografias digitais, a presença ou ausência de perda óssea vertical, medindo-se a distância da crista óssea à junção cemento-esmalte na mesial do primeiro molar inferior. A análise dos resultados do fêmur diferença estatisticamente significativa entre os grupos SHAM e OVX quanto aos valores medianos de densidade óssea, para todas as regiões. A comparação entre os grupos Controle, SHAM e OVX em relação à BMD da mandíbula nas regiões R1, R2, R3 e Global... . / This study had the objective to assess possible changes in mandibular and femoral bone mineral density resulting from estrogen deficiency due to ovariectomized, and the influence of these alterations of the periodontal disease induced in rats. Forty eight rats Holtzman, at the age of 90 days, were distributed in 5 groups: control group (n=9), group 1- SHAM without inducement of periodontal disease (n=11), group 2- SHAM with inducement of periodontal disease (n=10), group 3- OVX without inducement of periodontal disease (n=9) and group 4- OVX with inducement of periodontal disease (n=9). Nine animals were sacrificed on day 0 (baseline); 18 of them were subjected to OVX surgery and to SHAM simulate surgery. For the animals belonging to group 2 and 4, after a period of 120 days, were placed ligatures first inferior molar, wich remained on for 30 days. At the end of 5 months, the animals were killed and the mandible, femur and uteri were excised. Measures of BMD global and sub-regions of the mandible and femur were taken such as, mandible: global; R1 - condylar region; R2 - inferior border of mandible, and R3 - incisal region of mandible and for femur: global; R1 - distal epiphysis; R2 - proximal epiphysis and R3 - diaphysis. The presence or absence of the vertical loss bone was assessed by digital radiography, measuring the distance of the bone crest to the cementodentinal junction in the mesial of first inferior molar. The analysis of the femur results gives us evidence that there is a significant difference in median values of bone density between the groups SHAM and OVX, for all the regions. The comparison between the groups control, SHAM and OVX in relation to BMD of mandible in the region R1, R2, R3 and global, didn't show any significant difference (p>0,05) between themselves. The measures of... (Complete abstract, click electronic address below).

Made available in DSpace on 2014-06-12T23:02:48Z (GMT). No. of bitstreams: 2 arquivo8577_1.pdf: 1277931 bytes, checksum: 3fa83084d4bb4f85991aa2e7f000febd (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / A obesidade é uma excessiva acumulação de energia sob a forma de gordura corporal com prejuízos à saúde. O aumento da prevalência de obesidade em diferentes populações leva a acreditar que esta condição clínica caminha para ser a mais importante causa de doença crônica no mundo. O objetivo deste trabalho foi o de avaliar a importância da obesidade em especial a central e seus fatores de risco à saúde em homens adultos jovens por meio de revisão da literatura, bem como, realizar um estudo comparativo entre duas técnicas de avalição da composição corporal: a Antropometria e o Dual Energy X-ray absorptiometry (DXA). O delineamento do estudo foi do tipo transversal com seleção aleatória. Participaram 45 indivíduos com idades entre 20 e 30 anos, distribuídos em três grupos segundo o Índice de Massa Corporal (IMC), nas categorias peso normal, pré-obeso e obeso I. O referido estudo originou uma nova equação de predição para a gordura centralizada utilizando o perímetro abdominal (Pab) e a gordura do tronco medida pelo DXA em homens adultos jovens, permitindo ainda classificar os referidos indivíduos em risco à saúde de acordo com o Z-score usando a quantidade de gordura estimada pela referida equação

Background: Currently, body composition (BC) assessment is usually performed to diagnose disease states and accurately estimate certain types of tissues. In athletes, performing BC assessments helps gauge training and nutrition programs to see if they are adequately meeting the athlete’s needs to improve performance. Annual Dual Energy X-ray Absorptiometry (DXA) scans before the start of an athlete’s season can help identify an athlete’s preparedness or health before training begins. Objective: To assess the preseason BC of four collegiate sports: Men’s basketball, men’s baseball, women’s volleyball, and women’s soccer, for Fat Mass (FM), bone mineral density BMD), Fat-Free Mass (FFM), and visceral adipose tissue (VAT). Methods: DXA (Lunar iDXA, GE Healthcare) scans were performed before the start of pre-season training for Men’s Basketball, Baseball, Women’s Volleyball, and Women’s Soccer. End-season DXA scans were performed after the end of the regular season for Men’s Basketball and Baseball athletes. Visceral Adipose Tissue was measured using CoreScan software provided by GE and Fat Mass Index (FMI) and Fat-Free Mass Index (FFMI) were calculated from scanned values. Results: Between the various sports, there were several significant differences that were apparent. Height and percentage of Fat Mass (%BF) were significantly different between all sports except Women’s Volleyball and Women’s Soccer. BMI, VAT, and FFMI were significantly different between males and females. Changes over a season showed increased BMD in Men’s Basketball (2.79 to 2.99 Z-score, pre to end of season scan respectively; p < 0.001). No other observations were noticed to be significant. Conclusions: Sports-specific training and sex have large influences on the body composition of athletes. FMI and FFMI are two indices that may have a stronger indication to health than parameters considered for those who are sedentary and non-active. Female athletes have little to no amounts of VAT and this warrants further investigation.

Ziel der vorliegenden Studie war erstmals die systematische Untersuchung der intraindividuellen und seitenspezifischen Unterschiede verschiedener Rattenextremitäten (Femur, Tibia und Humerus) in Abhängigkeit der Knochenmineraldichte, gemessen mit der Zwei-Energie-Röntgenabsorptiometrie (DXA). Zudem sollte die Varianz bestehender Frakturmodelle verkleinert werden.:1. Einleitung 2. Literaturübersicht 2.1 Densitometrie 2.1.1 Zweienergie-Röntgen Absorptiometrie (DXA) 2.1.1.1 Evaluation der DXA – Technik 2.1.2 pQCT (periphere Quantitative Computertomographie) 2.1.3 QUS (Quantitativer Ultraschall) 2.2 Osteodensitometrie im Versuchsmodell 2.2.1 Einsatz von DXA beim Menschen 2.2.2 Einsatz von DXA bei Tieren 2.2.3 Einsatz von DXA bei Ratten 2.3 Biomechanische Testverfahren 2.3.1 Der Biegetest 2.3.1.1 Der 4–Punkt Biegetest 2.3.1.2 Der 3–Punkt Biegetest 2.3.1.3 Der Kompressionstest 2.3.1.4 Der Torsionstest 2.3.2 Biomechanische Tests in der Evaluation osteodensitometrischer Verfahren 3. Material und Methoden 3.1 Untersuchungsmaterial 3.2 Präparatentnahme 3.3 Knochenmessungen mit DXA 3.4 Biomechanische Testung 3.5 Statistische Analyse 4. Ergebnisse 4.1 Werte des Gesamtkollektivs mit seitenspezifischem Unterschied Knochendichte, Versagenslasten und Steifigkeit 4.2 Werte des Gesamtkollektivs ohne seitenspezifischen Unterschied Knochendichte, Versagenslasten und Steifigkeit 4.3 Korrelationen des Gesamtkollektivs untereinander und mit den Versagenslasten und der Steifigkeit 4.4 Korrelationen der Parameter der Versagenslasten 4.5 Korrelationen der Parameter der Steifigkeiten 4.6 Werte des Gesamtkollektivs mit gewichtsspezifischen Unterschieden 4.7 Korrelationen der Parameter im direkten seitenspezifischen Vergleich 5. Diskussion 5.1 Bedeutung der Fragestellung 5.2 Diskussion der Methoden 5.2.1 Osteodensitometrische Testverfahren 5.2.2 Biomechanische Testverfahren 5.3 Ergebnisdiskussion 5.4 Beantwortung der konkreten Fragestellung 5.5 Fazit 5.6 Ausblick 6. Zusammenfassung 7. Summary 8. Abbildungsverzeichnis 9. Tabellenverzeichnis 10. Literaturverzeichnis 11. Danksagung

We quantified confidence intervals (CIs) for T-scores for the lumbar spine and hip and determined the practical effect (impact on diagnosis) of variability around the T-score cutpoint of -2.5. Using precision data from the literature for GE Lunar Prodigy dual-energy X-ray absorptiometry (DXA) systems, the 95% CI for the T-score was ±0.23 at the lumbar spine (L1-L4), ± 0.20 at the total hip, and ±0.41 at the femoral neck. Thus, T-score variations of ±0.23 or less at the spine, ±0.20 at the total hip, and ±0.41 at the femoral neck are not statistically significant. When diagnosing osteoporosis, T-scores in the interval -2.3 to -2.7 for spine or total hip (after rounding to conform to guidelines from the International Society for Clinical Densitometry) and -2.1 to -2.9 for femoral neck are not statistically different from -2.5. Better precision values resulted in smaller 95% CIs. This concept was applied to actual clinical data using Hologic DXA systems. The study cohort comprised 2388 white women with either normal or osteopenic spines in whom the densitometric diagnosis of osteoporosis would be determined by hip T-scores. When evaluating actual patient T-scores in the range -2.5 ± 95% CI, we found that the diagnosis was indeterminate in approximately 12% of women when T-scores for femoral neck were used and in 4% of women when T-scores for total hip were used, with uncertainty as to whether the classification was osteopenia or osteoporosis. We conclude that precision influences the variability around T-scores and that this variability affects the reliability of diagnostic classification.

No description available.