New markers, prevalence and burden of osteoporosis and fragility fractures

In this PhD thesis, we aimed to determine the prevalence and burden of osteoporosis and fragility fractures in Portugal to provide evidence in support of new health strategies to improve clinical care and reduce or prevent disability and mortality among elderly. We also aimed to better identify senior women at high risk for a fragility fracture through the use of novel noninvasive biomarkers. To achieve this goal, we evaluated cellular (osteoblast) and tissue (bone mechanical properties) mechanism dysfunction to identify potential serum markers of bone fragility. We hypothesized that bone fragility in the elderly is associated with dysregulation of mineralization because of osteoblast terminal differentiation and disturbances in Wnt regulators [dickkopf-related protein (DKK)1 and DKK2, sclerostin (SOST) and secreted frizzled related protein-1 (sFRP-1)]. Moreover, we hypothesized that serum levels of Wnt regulators are associated with bone fragility and fractures and can constitute new markers for osteoporosis treatment decision. Finally, to create awareness and reduce new fragility fractures in Portugal, we aimed to develop national clinical consensus recommendations for osteoporosis diagnosis and treatment. The studies presented in this thesis crossed two main areas of clinical research, patientoriented mechanistic research, and epidemiological research. We used two samples of participants/patients. One sample was composed of patients undergoing hip replacement surgery (for osteoarthritis or a fragility fracture) in the Orthopaedic Department of Hospital de Santa Maria, Centro Hospitalar Lisboa Norte from 2008 to 2012. It was used to analyse clinical determinants of bone fragility and fractures in the elderly, particularly the associations between osteoblast dysfunction, bone mechanical properties, and fragility fractures. The other sample was a population based on a nationwide sample evaluated in the EpiReumaPt (2011-2013) study. Using the EpiReumaPt sample, we determined the prevalence and individual burden of osteoporosis in Portugal. Moreover, we analysed the prevalence, burden, and risk factors of fragility fractures in a particularly vulnerable stratum, senior women. The EpiReumaPt population was then followed in two more waves of evaluation (2011-2016) under the scope of the Epidemiology of Chronic Diseases (EpiDoC) cohort. Using data from the EpiDoC cohort, we analysed the association between serum markers of Wnt inhibitors (osteoblast regulators) and fragility fractures. Finally, a review of the literature was performed to develop national clinical recommendations regarding fracture risk assessment and osteoporosis treatment. In the first study of this thesis, using the EpiReumaPt sample, we found that 10.2% of Portuguese adults have osteoporosis. The prevalence is higher in women (17.0%) than in men (2.6%) and increases with age. Almost half (40.0%) of Portuguese adults 75 years and older have osteoporosis, and an osteoporosis diagnosis was associated with substantial physical function impairment but not with anxiety or depression symptoms. The second study, also using EpiReumaPt data, showed that self-reported fragility fractures were highly prevalent among senior women (20.7%). This high prevalence was in stark contrast with the low rate of osteoporosis treatment (13.9%). Non-hip and nonvertebral fractures (i.e., lower leg, wrist, humerus, rib, clavicle, and elbow fractures) accounted for the majority of fragility fractures, and clinical risk factors independently associated with prevalent fragility fractures were increased age, obesity, and lower distal bone mineral density (BMD). The challenge to better identify seniors (people aged ≥65 years old) at high risk for a fragility fracture led us to search for novel noninvasive biomarkers of bone fragility and fractures. To achieve this goal, we conducted patient-oriented mechanistic research, evaluating associations between cellular mechanism dysfunction and bone fragility among patients undergoing hip replacement surgery. In the third research work of this thesis, we demonstrated that when adjusted for differences in age, sex, and body mass index, the only macrostructural bone characteristic that remained significantly different between patients with hip fragility fractures and those with osteoarthritis was trabecular stiffness (which is linked to mineralization disturbances). Stiffness was lower in patients with fragility fractures. We also found that smoking habits and female sex were independently associated with lower stiffness in patients with a fragility fracture. In the fourth study of this thesis, we evaluated markers of osteoblast differentiation, as these are the cells responsible for the production of mineralized tissue. We found that osteocalcin (OCL) relative bone expression and the OCL/type 1 collagen, alpha 1 chain (COL1A1) expression ratio in bone (a marker of osteoblast terminal differentiation) were significantly lower in patients with hip fractures than in those with osteoarthritis. Consistent with these results, in a subset of patients, fewer osteoblasts stained for OCL in patients with a fragility fracture than in those with osteoarthritis. We also demonstrated that in patients with hip fractures, a low bone OCL/COL1A1 expression ratio was associated with worse trabecular mechanical behaviour. This work reinforced the importance of osteoblast dysfunction in bone intrinsic properties and fractures among the elderly. In our fifth study, we examined whether the Wnt inhibitors DKK1, DKK2, SOST, WIF-1, and sFRP-1 (regulators of osteoblast differentiation and bone formation) were associated with BMD or fragility fractures in a population-based cohort. Using EpiDoC cohort data, we found that low serum levels of DKK2 predicted low-impact fractures, independent of BMD, and clinical risk factors for fracture. For every 1 standard deviation decrease in DKK2, fracture risk increased by approximately 1.5-fold. Serum levels of DKK2 were not associated with vertebral or hip BMD. Our results suggest a possible interaction among BMD, FRAX score without BMD, and serum DKK2 levels in the assessment of fracture risk, which requires further investigation in a larger study with longer follow-up. The final work of this PhD thesis involved performing a literature review and establishing national consensus recommendations regarding fracture risk assessment and osteoporosis clinical management and treatment to change clinical practice and reduce the incidence of fragility fractures in Portugal. In conclusion, this thesis provided rigorous epidemiological data regarding the prevalence of osteoporosis and fragility fractures in Portugal. It contributed to refining fracture risk assessment through the identification of new serum markers (among regulators of osteoblast-mediated bone formation) of bone fragility and fractures. Mechanistic research regarding bone biomechanics and osteoblast dysfunction showed that fragility fractures are associated with reduced bone stiffness, reflecting mineralization disturbances. Furthermore, reduced osteoblast terminal differentiation was associated with poor bone mechanics and fractures. Finally, national consensus recommendations were created to improve fracture risk assessment of individuals, as well clinical management and treatment of osteoporosis, with the goal of reducing fragility fractures in Portugal

Alternating-current and direct-current electrical transport properties of diamond diodes with diamond surfaces of the different morphology

The alternating current (ac) conductance (f=200 Hz) was measured as a function of applied voltage at ambient temperature for two diodes with aluminium/diamond rectifying contacts on chemical vapour-deposited diamond films of 5 pm in thickness with different morphology, nucleation and growth surfaces. Comparison of direct current (dc) conductance curves (deduced from experimental current voltage curves) with ac conductance curves for the diodes revealed different transport mechanisms for two interfaces. The current voltage characteristic of gold/diamond/gold structures shows that the two interfaces have different resistance values. The results demonstrate that the nucleation surface has a greater surface density of states than the growth surface, and this contributes to electrical transport through the potential barrier. Cole Cole curves show a discrepancy between the Debye semicircle and experimental results and illustrate the fundamental differences between the two diodes. These results provide additional proof that the principal source of dispersion admittance is the surface states. The current voltage characteristic of diamond diodes with diamond films of 1 pm in thickness shows two distinct resistance states (high and low resistance). By applying an appropriate bias, resistance switching from one state to the other state can be achieved. The experimental results are discussed on the basis of filamentary conductio

Chemical and physical pretreatments of microalgal biomass

Non-axenic microalga Chlorella sorokiniana was cultivated in batch cultures, and its total sugar composition was determined. The microalga under study showed a total sugar concentration of 21.44 ± 0.46% (w/w). The effects of freeze-drying, oven-drying, freezing and thawing, chemical and the combination of hydrothermal and chemical pretreatments were evaluated. In the combined pretreatment different concentrations of H2SO4 and reaction times were also optimized. It was possible to determine that the sugar extraction yields more significant were 59.5% for the lyophilization, 6.2% with 6 cycles of freeze and thawing and around 100% for 2 and 4% (v/v) of H2SO4 at 121 °C for 30 min. Some of the methods that were described in this study are interesting to facilitate cost-efficient conversion of microalgal biomass into biofuels.info:eu-repo/semantics/publishedVersio

Digestibility studies in rainbow trout (Oncorhynchus mykiss)

The bioavailability of nutrients in commercial feeds available in Portugal was evaluated in three size groups (40g. l00g and 180g) of rainbow trout (Oncorhynchus mykiss) on two private farms. Dietary crude fibre level was used as the digestibility marker. A series of laboratory trials was also carried out to investigate the influence of various biotic and abiotic factors on apparent digestibility coefficients and to provide corroboration for the field survey. The principal factors influencing apparent digestibility values during the field survey were diet quality, temperature and water-dissolved oxygen. The apparent digestibilities of crude protein, organic matter and dry matter were strongly inversely correlated with dietary fibre level in the three size groups of farmed trout. In addition, significant positive correlations were obtained between lipid level in commercial feeds and the organic matter digestibility coefficients. Under controlled conditions, dietary lipid level (7%, 14% and 21%) had a marked effect on digestibility, the highest digestibility values being obtained with the 21% lipid diet (87.77%, 76.55% and 70.46%) compared to 84.59%, 63.25% and 57.74% with the 7% lipid diet for crude protein, organic matter and dry matter, respectively. A signification correlation was also obtained between all apparent digestibility coefficients and the feed protein level for all size groups of fish studied in the field. In the laboratory, however, only at 21®C was there a marked effect and significantly higher digestibility values were obtained with the higher protein (45%) diet (85.98%, 83.74%, 80.37% and 84.54% for protein, organic matter, dry matter and energy, respectively) as compared to the lower protein (30%) diet (74.16%, 71.66%, 65.54% and 68.70% for protein, organic matter, dry matter and energy, respectively). General increases in apparent digestibility values of more than 10% were obtained between the lower (10°C or 15°C) and the higher (21 °C or 22°C) experimental temperatures, much higher than values previously reported. Food intake was shown to be directly dependent on dissolved oxygen (D.O.) and for one unit decrease of D.O. food intake decreased by about 0.5% or 0.25% body weight/day whether fish were subjected to an abrupt decrease of water O2 level or to prolonged hypoxia. Furthermore, apparent digestibility values were significantly increased when fish were subjected to prolonged hypoxia. Feeding frequency (1, 2 or 4 meals/day) did not influence digestibility, whereas time of day and fish size did have a significant effect. Mean digestibility values estimated either from chromic oxide or crude fibre analysis were significantly different. The difference was, however, very small and bearing in mind the advantages of an internal marker as compared to an added marker, this study has shown that crude fibre is a useful tool for feed evaluation, especially in practical situations. The need for, and importance of, digestibility evaluations is discussed and summarised in the form of a conceptual model

Atividade física extracurricular dos adolescentes

A atividade física regular é fundamental para garantir um ótimo crescimento e desenvolvimento dos adolescentes, onde o envolvimento com outras variáveis ambientais influencia o estado de saúde dos “adultos do futuro”. Tratou-se de um estudo não experimental, de observação e de metodologia transversal, cujo objetivo foi recolher informações sobre a atividade física extracurricular realizada pelos adolescentes matriculados nas escolas de Bragança através do preenchimento de um questionário sobre a prática de exercício físico extracurricular. Participaram 600 adolescentes com idades compreendidas entre os 12 e os 18 anos matriculados nos estabelecimentos de ensino da cidade de Bragança. Os resultados obtidos evidenciaram que a prática de exercício físico extracurricular era efetuada por 53,9% dos jovens, verificando-se que o sexo dos adolescentes influenciava a prática de desporto (ρ=0,000), tal como a idade (ρ=0,048). Eram os rapazes mais novos que praticavam mais frequentemente desporto extracurricular, destacando-se o futebol, outra atividade (dança e musculação) e o basquetebol. Dos adolescentes que praticavam desporto extracurricular, 15,83% realizavam dietas de restrição alimentar. Em relação aos adolescentes que não praticavam exercício físico extracurricular, 11,78% também recorriam à dieta. Verificou-se que a prática de exercício físico era estatisticamente independente da realização de dietas (ρ=0,157). Para além disso, foi possível constatar que 39,1% dos jovens utilizavam o carro dos familiares como forma de transporte para a escola, seguindo-se os jovens que se deslocavam a pé (35,1%). Relativamente ao trajeto realizado a pé, a maioria demorava entre 5 a 15 minutos entre o percurso casa-escola. Visto que um número significativo de adolescentes matriculados nas escolas de Bragança não praticava atividade física extracurricular, torna-se imperativo a promoção de ações que lhes incutam este hábito de vida saudável

Cuttings of Aloysia citriodora Palau: greenhouse trials under different rooting conditions

A espécie aromática e medicinal Aloysia citrodora Palau, Verbenaceae, conhecida como limonete, erva -luísa ou lúcia- -lima, é uma das mais cultivadas e comercializadas em Portugal. A instalação e manutenção dos campos de cultivo exigem material de propagação em quantidade e com a qualidade e uniformidade que assegurem a comercialização da biomassa, de acordo com os padrões dos compradores. A possibilidade dos produtores obterem as próprias plantas depende da disponibilidade de material vegetativo ao longo de todo o ano e dos processos de rizogénese que nem sempre são fáceis de induzir. Realizaram -se ensaios de enraizamento de estacas caulinares lenhosas e semilenhosas, preparadas a partir de plantas- -mãe cultivadas em campo comercial ao ar livre. O delineamento experimental incluiu estacas caulinares de diferente espessura, diferentes substratos (perlite e composto orgânico comercial), hormona de enraizamento (com e sem auxina), condições de humidade (com e sem nebulização) e temperatura (em bancada aquecida e sem aquecimento). Numa segunda experiência avaliou -se a capacidade de enraizamento de material vegetal colhido ao longo de todos os meses do ano a partir de plantas cultivadas em estufa. As estacas colocadas em perlite originaram percentagens de enraizamento mais elevadas do que as estacas em substrato orgânico, embora os valores tenham sido sempre inferiores a 20%. O substrato orgânico deu melhores resultados, conjugando estacas grossas e ausência de nebulização, por oposição a estacas mais finas com nebulização. Ao longo do ano, as percentagens de enraizamento foram máximas em maio, com valores superiores a 70%. As estacas semilenhosas do período estival originaram percentagens de enraizamento particularmente baixas.Aloysia citriodora Palau, Verbenaceae, known as lemon verbena, is one of the most cultivated and marketed medicinal and aromatic plants in Portugal. Biomass quality and uniformity of the plant material according to stakeholders’ standards are market criteria requiring important amounts of biomass supplied by producers’ organic fields. However, in order to satisfy such biomass needs, horticulturists should provide vegetative propagated plant material to install new fields or to regenerate the existing ones. Producing cuttings depends on the availability of plant material throughout the year and on rooting processes which could not be easy to induce. Woody and softwood stem cuttings were prepared from plants grown in the field. Different substrates, thickness of propagated material and exogenous application of auxin were compared in their capability to induce root and shoot formation. In other experiment, the rhizogenic ability of plant material was monthly assessed for a year from plants grown in a greenhouse. Cuttings placed in perlite presented higher percentages of rooting than those in organic substrate, although in both cases values of root formation were always below 20%. Organic substrate combined with thick cuttings and absence of nebulization had a better performance than thin cuttings with nebulization. Throughout the year, the rooting percentages were highest in May, with values greater than 70%. The softwood cuttings from summer period originated particularly low rooting percentagesinfo:eu-repo/semantics/publishedVersio

Pertinência educacional da educação ambiental: perceção dos docentes do 3º ciclo do ensino básico do distrito de Bragança

A importância das questões ligadas ao ambiente enquanto matéria de estudo associada à formação dos jovens é atualmente unânime. Porém, ao nível da docência, os professores deparam-se com uma grande diversidade e quantidade de conteúdos, sem que haja uma orientação muito precisa de como proceder à sua incorporação na prática letiva. Este trabalho enquadra-se num estudo mais amplo realizado no âmbito do mestrado em Educação Ambiental e cujo objetivo é conhecer a perceção dos professores do 3.º Ciclo do Ensino Básico sobre Educação Ambiental. A técnica de recolha de dados utilizada foi o inquérito por questionário. A análise fatorial permitiu obter sete fatores aglutinadores dos temas abrangidos pelo instrumento. Neste caso destacamos os dados relativos à pertinência educacional da Educação Ambiental. A partir dos resultados em função das variáveis género, situação profissional, forma de profissionalização, tempo de serviço, verifica-se que as opiniões mais favoráveis provêm, respetivamente: das professoras; dos professores do quadro; dos professores que tiveram estágio integrado e dos professores com tempo de serviço entre 21 e 25 anos. A sim, o estudo mostra que há, notoriamente, concordância face ao fator pertinência educacional. s Conclui-se que a Educação Ambiental é vista como uma dimensão de educação abrangente que abre caminhos para a reflexão de problemas ambientais e para o desenvolvimento de valores que conduzem à alteração de comportamentos

Estacaria de Aloysia citrodora Palau: ensaios de enraizamento em estufa sob diferentes condições

A espécie Aloysia citrodora Palau, Verbenaceae, conhecida como limonete, erva-Luísa ou lúcia-lima, é uma das espécies de PAM mais cultivadas e comercializadasem Portugal. Segundo alguns produtores, no momento da instalação e regeneração dos campos de produção ou da mera substituição de falhas, a obtenção de material vegetativo, em quantidade e com as característicasde qualidade e uniformidade (e.g. textura, consistência, cor, aroma, composição química) que garantem a comercialização da biomassa está dependente da disponibilidade dos viveiristas ou da capacidade dos produtores produzirem as próprias plantas. A propagação vegetativa, nomeadamente a estacaria, pode ser uma respostaajustada às necessidades. Contudo, nem sempre os resultados são favoráveis porque a produção de estacas durante todo o ano está limitada à disponibilidade de material vegetativo e os processos de rizogénese podem ser difíceis de induzir, não ocorrendo a formação de raízes ou obtendo-se um sistema radicular deficiente, que provoca a secagem e mortalidade das estacas. Com o objectivo de obter informação sobre as taxas de enraizamento de estacaria de limonete realizaram-se ensaios de enraizamento de estacas caulinares, lenhosas e semilenhosas, preparadas a partir de plantas cultivadas e mantidas em estufa. Numa primeira etapa, ensaiaram-se substratos e condições de temperatura e humidade. Na segunda fase, testou-se a capacidade de enraizamento de material vegetal colhido ao longo de todos os meses do ano.info:eu-repo/semantics/publishedVersio

Hábitos alimentares dos adolescentes

A adolescência corresponde a um grupo etário marcado por diversas mudanças fisiológicas, psicológicas, afectivas, intelectuais e sociais,revelando-se um grupo susceptível a maiores riscos nutricionais. OBJECTIVOS: Obter informações sobre hábitos alimentares dos adolescentes matriculados nas escolas da cidade de Bragança.METODOLOGIA: Estudo de metodologia transversal sendo a amostra obtida pelo processo de amostragem probabilística, constituída por 600 adolescentes. A informação foi obtida através de 2 questionários estruturados.Para a análise estatística dos resultados obtidos foi utilizado o programa SPSS versão 14.0 (2005), para o Windows da Microsoft, recorrendo-se a testes paramétricos e não paramétricos para o estudo da inferência estatística.RESULTADOS: Relativamente à frequência de consumo alimentar, os resultados obtidos evidenciaram que as diferenças de consumos médios entre rapazes e raparigas não eram estatisticamente significativas, à excepção do consumo de carne, pescado e ovos, onde se verificou um consumo superior por parte dos rapazes.Relativamente às porções de alimentos ingeridas por ambos os sexos, e de acordo com o recomendado pela Roda dos Alimentos Portuguesa, verificou-se que para os alimentos dos grupos de cereais e derivados e tubérculos, frutas, produtos hortícolas e leguminosas, o consumo foi em termos estatísticos significativamente inferiores aos valores recomendados, com excepção do grupo das carnes, pescado e ovos em que o consumo foi significativamente superior ao recomendado. No que concerne ao consumo de alimentos doces, açúcar e bebidas alcoólicas registou-se um maior consumo entre os rapazes. CONCLUSÕES: Analisando o perfil alimentar dos adolescentes de Bragança, constatou-se um afastamento do padrão alimentar intrínseco ao conceito de dieta mediterrânea. Através dos resultados obtidos sobre os principais hábitos alimentares destes jovens, torna-se imperioso orientá-los relativamente às suas escolhas alimentares