Osteoporosis is caused by loss of bone mineral content, which leads to bone fractures or structural deformations of bone. Osteoporosis usually occurs when people get older, after menopause in women, or it can be caused by a lack in the intake of a sufficient amount of calcium and vitamin D. Until recently, osteoporosis was considered to be an unavoidable part of aging, but today, approved and effective treatments can be used to deal with the consequences. At present, determination of risk of bone abnormalities is done by measuring the density of bone (largely determined by calcium content). Dual energy X-ray Absorptiometry (DXA) is the gold standard technique for measuring bone mineral density (BMD). Even though BMD is one of the principal determinants of bone strength, BMD measurements do not give information about variation of trabecular structure of bone. That's why DXA alone has limited ability to predict who will sustain an osteoporotic fracture. To predict fracture risk of patients, the texture analysis of the DXA images is of interest as a measure to predict fracture in addition to BMD. This thesis focuses on the application of texture analysis to digital images of bone scans of patients at risk of fracture and osteoporosis. Texture analysis was performed by analyzing the variation of grey level patterns of pixels of DXA images. Texture analysis of such images will give an idea of the variation of grey scale patterns of pixels between normal and osteoporotic DXA images of bone. Existing texture analysis measures such as contrast measures of co-occurrence matrices and mean slope value of fractal dimension based measure are used to analyze the texture of DXA images. An alternative partitioning technique is proposed as a measure of the texture analysis.

Osteoporosis is caused by loss of bone mineral content, which leads to bone fractures or structural deformations of bone. Osteoporosis usually occurs when people get older, after menopause in women, or it can be caused by a lack in the intake of a sufficient amount of calcium and vitamin D. Until recently, osteoporosis was considered to be an unavoidable part of aging, but today, approved and effective treatments can be used to deal with the consequences. At present, determination of risk of bone abnormalities is done by measuring the density of bone (largely determined by calcium content). Dual energy X-ray Absorptiometry (DXA) is the gold standard technique for measuring bone mineral density (BMD). Even though BMD is one of the principal determinants of bone strength, BMD measurements do not give information about variation of trabecular structure of bone. That's why DXA alone has limited ability to predict who will sustain an osteoporotic fracture. To predict fracture risk of patients, the texture analysis of the DXA images is of interest as a measure to predict fracture in addition to BMD. This thesis focuses on the application of texture analysis to digital images of bone scans of patients at risk of fracture and osteoporosis. Texture analysis was performed by analyzing the variation of grey level patterns of pixels of DXA images. Texture analysis of such images will give an idea of the variation of grey scale patterns of pixels between normal and osteoporotic DXA images of bone. Existing texture analysis measures such as contrast measures of co-occurrence matrices and mean slope value of fractal dimension based measure are used to analyze the texture of DXA images. An alternative partitioning technique is proposed as a measure of the texture analysis.

Objectives: No nationwide paediatric reference standards for bone mineral density (BMD) are available in China. We aimed to provide sex-specific BMD reference values for Chinese children and adolescents (3-18 years). Methods: Data (10 818 participants aged 3-18 years) were obtained from cross-sectional surveys of the China Child and Adolescent Cardiovascular Health in 2015, which included four municipality cities and three provinces. BMD was measured using Hologic Discovery Dual Energy X-ray Absorptiometry (DXA) scanner. The DXA measures were modelled against age, with height as an independent variable. The LMS statistical method using a curve fitting procedure was used to construct reference smooth cross-sectional centile curves for dependent versus independent variables. Results: Children residing in Northeast China had the highest total body less head (TBLH) BMD while children residing in Shandong Province had the lowest values. Among children, TBLH BMD was higher for boys as compared with girls; but, it increased with age and height in both sexes. Furthermore, TBLH BMD was higher among US children as compared with Chinese children. There was a large difference in BMD for height among children from these two countries. US children had a much higher BMD at each percentile (P) than Chinese children; the largest observed difference was at P50 and P3 and the smallest difference was at P97. Conclusions: This is the first study to present a sex-specific reference dataset for Chinese children aged 3-18 years. The data can help clinicians improve interpretation, assessment and monitoring of densitometry results.

Introduktion: Hos den äldre delen av befolkningen är sarkopeni och sjukdomar som uppstår till följd av förändrad kroppskomposition ett stort problem. Träning bedöms ha stor påverkan gällande båda dessa ohälsomarkörer. Därav är det kliniskt relevant att titta på hur en 12 veckor lång träningsintervention påverkar kroppskompositonen och hur denna eventuella förändring korrelerar med prestationsmått.   Metod: Träningsinterventionen bestod av medel- och högintensiv icke- viktbärande träning utförd på träningscykel, 2 gånger veckovis under 12 veckor. Dubbel-energi röntgenabsorptiometri (DXA) genomfördes gällande kroppskompositionsmått. Parade t-test har gjorts på tidigare insamlade data för att undersöka eventuella förändringar innan och efter träningsintervention. Signifikanta förändringar undersöktes sedan mot varandra i en korrelationsanalys. Prestationsmått som analyserades var Chair- stand 30 sekunder, Borg Cycle Strength Test och Maximal volontär kontraktion. Kroppskompositionsmått var viceral fettmassa, total fettmassa, total fettfri massa, och total lean massa, samt fettmassa ben, fettfri massa ben och lean massa ben. Resultat: De enda mått som under träningsintervention förändrades signifikant hos både kvinnor och män var prestationsmåttet Chair-stand och kroppskompositionsmåttet total lean massa. Sambandet dessa mått emellan var ej signifikant utan snarare svagt negativt.  Diskussion: Resultatet indikerar att en förbättrad anaerob kapacitet i större utsträckning beror på andra faktorer än förändrade kroppskompositionsmått. Förbättrande faktorer kan vara neuromuskulära adaptioner, förmåga att aktivera befintlig muskelmassa och metabola processer. Konklusion: Vårt resultat visar på att en 12 veckor lång träningsintervention är tillräckligt lång tid för att signifikant förändra total lean massa. Dock beror den signifikant förbättrade anaeroba kapaciteten främst på andra faktorer då sambandet dessa mått emellan var svagt negativt.

Probiotics/prebiotic supplementation represents a viable option for addressing systemic inflammation and chronic disease risk resulting from excessive body weight. The purpose of this feasibility study was to determine if 90-d of supplementation with prebiotic and probiotic could alter mRNA responsible for inflammation and subsequently metabolic health in weight stable overweight adults. Participants were advised to not change their diet or exercise habits during the study. All protocols were approved by the University IRB and participants gave written informed consent. Participants were randomly assigned to either placebo (N=7; rice flour) or combined (N=8) prebiotic (PreticX® Xylooligosaccharide; 0.8 g/d; ADIP) and probiotic (MegaDuo® Bacillus subtilis HU58 and Bacillus coagulans SC-208; 3 Billion CFU/d) and measurements were made at baseline, 30, 60, and 90-d. Whole body DXA scans (GE iDXA®) and blood 574-plex mRNA analysis (Nanostring®) were used to generate primary outcomes. Compared to placebo, supplementation was associated with a 36% reduction in visceral adipose tissue (p = 0.001). Supplement resulted in significant, differential expression of 15 mRNA associated with adipose tissue inflammation, systemic inflammation, and/or chronic disease risk. The key findings support that 90-d prebiotic/probiotic supplementation may be associated with an improved metabolic health, reduced adipose tissue inflammation, reduced systemic inflammation, and reduced chronic disease risk. Collectively these findings demonstrate the potential of a prebiotic/probiotic supplement to impact metabolic health risk independent of weight loss in free-living individuals.

Osteoporosis is a debilitating and costly disease of the skeleton characterized by low bone mass and structural deterioration of bone tissue leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Current data suggest that at present time, 7.8 and 21.8 million women have osteoporosis and osteopenia respectively. The development of osteoporosis and related fracture in later life depends not only on the rate of bone loss in adulthood, but also on the amount of bone present at skeletal maturity. Oral contraceptives (OC), because of their capacity to diminish concentrations of free testosterone and estrogen, have been purported to affect bone mass in young adult women, but results have proven inconsistent. Further, positive skeletal effects of exercise training are thought to be compromised by use of OCs in skeletally immature females. PURPOSE: To assess the independent and synergistic effects of OC use on bone mineral density (BMD) and long bone mechanical bending stiffness (EI) in college-aged females after unilateral isokinetic resistance training. METHODS: Forty six females (age 20 +/- 1.4 yr, height 163.8 +/- 6.2cm, weight 58.9 +/- 8.6kg, fat 27.9 +/- 4.8%) were categorized as OC users (OC, N=22) or non-users (NOC, N=24). Subjects participated in 32 weeks (3 d/wk) of unilateral arm and leg training at an angular velocity of 60 degrees/s using isokinetic dynamometers. BMD and EIMRTA were assessed using dual-energy x-ray absorptiometry (DXA) and mechanical response tissue analysis (MRTA), respectively. RESULTS: Total leg and arm muscular strength of the trained limb increased by 16% and 15%, respectively (p < 0.001), beyond changes observed in the control limbs. Total body BMD increased from baseline for NOC subjects (p < 0.05), but not for OC users. This difference failed to show significance (p = 0.069) when comparisons were run between NOC and OC groups. Increases in ulnar BMD (p < 0.01 for all limbs) and BMD of the trained total hip (OC, p < 0.001; NOC, p < 0.05) occurred irrespective of contraceptive status. Positive changes in EI were conflicting, occurring in the trained ulna for the NOC group (p < 0.05), and trained tibia for OC users (p < 0.05). Tibial BMD increased only for the untrained leg in NOC subjects (p < 0.01). No between group differences were found to be significant, nor were differences between trained vs. untrained, and weight bearing (tibia) vs. non-weight-bearing (ulna) limbs found to be significant. CONCLUSION: These results suggest that oral contraceptives may limit attainment of total body peak bone mass in young adult females. Skeletal maturation in the ulna appeared to be unaffected by exercise training and OC use. Positive effects of exercise training on the total hip were seen in both groups, irrespective of OC status. Conversely, exercise training and use of OCs use may limit the attainment of bone mass in the tibia. Further studies are needed to determine the interactive effects of OC use and isokinetic resistance training on measures of total body and site-specific bone status. / Master of Science

Modelos antropométricos são alternativas mais usadas no estudo da composição corporal (CC) de campo, contudo as propostas bicompartimentais acarretam vieses na sua interpretação. Os objetivos deste estudo foram quantificar, relacionar, comparar e predizer a CC de jovens, considerando idade, maturação e prática esportiva, a partir de uma análise multivariada referenciada por Absortometria de Raios X de Dupla Energia (DXA). Quatrocentos e oito sujeitos de 8 a 18 anos, foram agrupados em esportistas (ES) e não-esportistas (NE), classificados por idade e pico de velocidade de crescimento (PVC). Foram determinadas a massa de gordura (MG), massa óssea (MO) e massa muscular (MM). Das 36 medidas antropométricas iniciais, nove foram as resultantes no modelo utilizado ( n &Upsilon; m = n &Chi; ( r + 1) ( r + 1) &#946; m + n &epsilon; m ). O aumento contínuo da CC com a idade, apresentou expressivas variações inter-individuais nas idades próximas ao PVC. As mudanças da CC foram previsíveis e apresentaram velocidades distintas de desenvolvimento, mais coincidentes com as alterações maturacionais. A equação antropométrica multivariada apresentou altos coeficientes de determinação e baixos erros de estimativa. A validação interna do modelo (PRESS = 0,95; 0,93; 0,96), o coeficiente (Q2 = 0,97; 0,97; 0,98) e a confiabilidade (SPRESS = 0,09; 0,01; 0,08), respectivamente para MG, MO e MM, permitiram recomendar sua aplicação para populações com características semelhantes a esta amostra. Não houve diferenças significantes entre ES e NE na MM e MO, mas foram encontradas na MG / Anthropometric models are the most common alternatives used in field body composition (BC) studies, but the bicompartmental models can cause bias in analysis. The objectives of this study was to quantify, relate, compare and predict the BC on youth, considering age, maturation and sport practice from a referenced multivariate analysis by Dual Energy Absorptiometry X-Ray (DXA). Four hundred and eight subjects from 8 to 18 years old were grouped in sport practitioners (SP) and non practitioner (NP), classified by age and peak high velocity (PHV). Fat mass (FM), bone mass (BM) and muscle mass (MM) was determined. From the 36 anthropometric initial measurements, nine resulted in the utilized model ( n &Upsilon; m = n &Chi; ( r + 1) ( r + 1) &#946; m + n &epsilon; m ). The continuous increase of the BC related by age expressed inter-individual variations on the PHV ranging ages. The body composition changes were predictable and showed distinct development velocities that coincide with the maturational modifications. The equations showed high determinations coefficients and low estimative errors. Internal validation of the model (PRESS = 0.95; 0.93; 0.96), the coefficient (Q2 = 0.97; 0.97; 0.98) and reliability (SPRESS = 0.09; 0.01; 0.08) respectively for FM, BM and MM allowed to recommend its application for populations with the same characteristics of the subjects in this study. There was no significant differences between SP and NP for MM and BM, but was differences on FM

Sarcopenia (Sc) é uma doença caracterizada por sintomas patológicos sem causas específicas que acomete parte dos idosos. A Sc promove reduções na massa muscular (MM) e força muscular (FM), com sérios impactos funcionais e motores. A força de preensão manual (FPM) utilizada para diagnosticar Sc não é representativa da FM global, especialmente para FM de membros inferiores (MMII), quando idosos passam por intervenção com treinamento de FM. Embora utilizada para definir a Sc, FM é considerada de forma absoluta ou relativizada pela massa corporal (MC), cuja relação nem sempre é linear. Assim, o objetivo deste estudo foi estabelecer parâmetros válidos para diagnóstico da Sc, a partir de diferentes expressões da FM de MMII em idosos. Uma amostra de 98 idosos fisicamente independentes foi medida pela absorciometria radiológia de dupla energia (DXA) para determinação do Tecido Mole Magro apendicular. Os idosos foram classificados por sexo e Sc (1=Sc; 0=não Sc), segundo os critérios do European Working Group on Sarcopenia in Older People (EWGSOP). A FM de extensão de joelhos (FMEJ) isocinética determinada a 60º/s (Biodex, System 4 Pro), foi considerada como FM referencial (FMEJTorquePico-60°/s), e a FMEJ Estimada em cadeira extensora (CMáxEstFMEJcad-ext), em protocolo de repetição máxima. Análise descritiva com medidas de tendência central foi utilizada para caracterização da amostra. A validação da FMEJ Estimada foi testada por correlação com a FMEJ de referência. Os valores de CMáxEstFMEJcad-ext foram relativizados pela massa corporal (FMEJ/MC) e por ajustes alométricos (FMEJ/MCb), onde b é o expoente gerado por regressão log-linear entre FMEJ e MC. Para determinar um modelo explicativo da Sc a partir de cada expressão da CMáxEstFMEJcad-ext (absoluta, FMEJ/MC e FMEJ/MCb) foi empregada a regressão logística simples. Os pontos de corte para Sc a partir da CMáxEstFMEJcad-ext foram definidos pela curva Característica de Operação do Receptor (ROC) e localizados pelo índice de Youden. As análises foram realizadas no Statistical Product and Service Solutions (SPSS) 20.0 e MedCalc 15.2 com níveis de significância previamente estabelecidos (?=0,05). Os resultados indicaram que a Sc esteve presente em 12,9% dos homens e 9,0% das mulheres. Houve alta correlação entre a medida de FMEJ de referência e a Estimada (r=0,81), mesmo entre idosos com Sc (r=0,72). Os expoentes b obtidos foram de 0,96 e 0,70 para homens e mulheres, respectivamente. Na regressão logística, as expressões relativas (FMEJ/MC e FMEJ/MCb) não explicaram a probabilidade para ocorrência da Sc em nenhum dos sexos. Somente a CMáxEstFMEJcad-ext absoluta explicou a chance para homens (?2=3,869; p=0,049) e mulheres (?2=4,145; p=0,042). A área abaixo da curva foi elevada (AUC>0,70), com pontos de corte de 65,0kg para homens e 34,9kg para mulheres. Conclui-se que a CMáxEstFMEJcad-ext é uma medida válida para monitorar Sc como parâmetro de FM em idosos, mesmo quando apresentam Sc. Os limiares de carga (kg) propostos como pontos de corte podem ser usados em um simples teste FMEJ da prática clínica profissional. Além disso, tem boa sensibilidade para monitorar a distância do ponto corte para Sc, o que não é possível com o modelo dicotômico do EWGSOP / Sarcopenia (Sc) is a disease characterized by pathological symptoms without specific causes that affects part of the elderly. Sc promotes reductions in muscle mass (MM) and muscle strength (MS), with serious functional and motor impacts. The handgrip strength (HS) used to diagnose Sc is not representative of global MS, especially for lower limb (LL) MS, when the elderly go through an intervention with MS training. Although used to define Sc, MS is considered absolutely or relativized by body mass (BM), whose relationship is not always linear. Thus, the objective of this study was to establish valid parameters for the diagnosis of Sc, from different MS expressions of LL in the elderly. A sample of 98 physically independent elderly subjects was measured by dual energy absorptiometry (DXA) to determine appendicular lean soft tissue. The elderly were classified by sex and Sc (1=Sc; 0=not Sc), according to the criteria of the European Working Group on Sarcopenia in Older People (EWGSOP). The isokinetic knee extension MS (KEMS) determined at 60º/s (Biodex, System 4 Pro) was considered as referential (KEMSPeakTork-60°/s), and KEMS Estimated in extensor chair (EstMaxLoadKEMSext-ch), in maximal repetition protocol. Descriptive analysis with measures of central tendency was used to characterize the sample. Validation of the estimated KEMS was tested by correlation with the reference KEMS. The values of EstMaxLoadKEMSext-ch were relativized by body mass (KEMS/BM) and by allometric adjustments (KEMS/BMb), where b is the allometric exponent generated from the log-linear regression between KEMS and BM. To determine an explanatory model of Sc from each expression of EstMaxLoadKEMSext-ch (absolute, KEMS/BM and KEMS/BMb), simple logistic regression was used. The cutoff points for Sc from the EstMaxLoadKEMSext-ch were defined by the Receiver Operating Characteristic (ROC) curve and located by the Youden index. The analyzes were performed in Statistical Product and Service Solutions (SPSS) 20.0 and MedCalc 15.2 with previously established levels of significance (? = 0.05). The results indicated that Sc was present in 12.9% of men and 9.0% of women. There was a high correlation between the reference KEMS and the estimated (r=0.81), even among the elderly with Sc (r=0.72). The exponent b obtained was 0.96 and 0.70 for men and women, respectively. In the logistic regression, the relative expressions (KEMS/BM and KEMS/BMb) did not explain the probability for occurrence of Sc in any of the sexes. Only absolute EstMaxLoadKEMSext-ch explained the chance for males (?2=3,869, p=0.049) and females (?2=4.145, p=0.042). The area below the curve was elevated (AUC>0.70), with cutoff points of 65.0kg for men and 34.9kg for women. It is concluded that the EstMaxLoadKEMSext-ch is a valid measure to monitor Sc as MS parameter in the elderly, even when they present Sc. Load thresholds (kg) proposed as cutoff points can be used in a simple clinical practice test. In addition, it has good sensitivity to monitor the distance from the cut point to MS, which is not possible with the dichotomous model of the EWGSOP

Les buts de cette thèse étaient d’évaluer les taux de 25(OH)D chez des jeunes adultes Libanais et d’explorer les relations entre la 25(OH)D, la vitamine D libre et plusieurs paramètres osseux dans la même population. Dans un premier temps, nous avons démontré que l’insuffisance en 25(OH)D est très fréquente chez les jeunes adultes libanais (66 % des femmes vs. 50,7 des hommes) et que les taux de 25(OH)D ne sont pas des déterminants positifs de la DMO. Dans un deuxième temps, nous avons démontré que la 25(OH)D était positivement corrélée au BSI et au CSI dans les deux sexes et que certaines de ces corrélations ont persisté même après ajustement pour l’IMC. Dans un troisième temps, nous avons démontré que les taux de 25(OH)D sont positivement corrélés au TBS dans les deux sexes et que les valeurs de TBS sont supérieures chez les sujets ayant des taux suffisants (> 30 ng/ml) en 25(OH)D par rapport aux sujets ayant des taux insuffisants (< 30 ng/ml) en 25(OH)D. Dans un dernier temps, la vitamine D libre était positivement corrélée à plusieurs paramètres osseux dans les deux sexes ; certaines corrélations ont persisté même après ajustement pour le poids corporel. En conclusion, la 25(OH)D est un déterminant positif de plusieurs paramètres osseux chez les jeunes adultes Libanais. De plus, la vitamine D libre semble être un déterminant positif de plusieurs paramètres osseux dans cette population. La mesure des deux formes de vitamine D (25(OH)D et vitamine D libre) est intéressante pour l’évaluation et la prévention de l’ostéoporose. / The aims of this study were to evaluate the levels of 25(OH)D in a group of young Lebanese adults and to explore the relations between 25(OH)D, free vitamin D and many bone parameters in the same population. First, we have demonstrated that vitamin D insufficiency is very frequent in young Lebanese adults (66% in women vs. 50.7 % in men) and that levels of 25(OH)D are not positive determinants of BMD. Second, we have shown that 25(OH)D was positively correlated to BSI and CSI in both sexes, and some of these correlations remained significant after adjustment for BMI. Third, we have demonstrated that 25(OH)D levels were positively correlated to TBS in both sexes and that TBS values were higher in vitamin D sufficient (> 30 ng/ml) subjects compared to vitamin D insufficient subjects (< 30 ng/ml). Finally, free vitamin D was positively correlated to many bone parameters in both sexes; some of these correlations remained significant after adjustment for body weight. In conclusion, 25(OH)D is a positive determinant of many bone parameters in young Lebanese adults. Moreover, free vitamin D seems to be a positive determinant of many bone parameters in this population. The measurement of both forms of vitamin D (25(OH)D and total vitamin D) is interesting for the evaluation and the prevention of osteoporosis.

Hip fracture has been identified as one of the main health problems in the elderly. To improve the accuracy in assessing subject-specific hip fracture risk, this study proposed normalized cortical bone thickness (NCBT) estimated from patient’s hip DXA as an alternative predictor of hip fracture risk. Hip fracture risk index (HFRI) derived from DXA-based finite element model was utilized as a baseline for evaluating the effectiveness of NCBT in predicting hip fracture risk. It was found that NCBT at the lateral side of the narrowest femoral neck had the strongest correlation with femoral neck HFRI among the six locations of the proximal femur. This study suggests that it is possible to use NCBT as a surrogate for a quick evaluation of hip fracture risk. Yet its clinical performances such as sensitivity to therapy effectiveness and the ability to discriminate clinical fracture cases will be investigated in a future study.