In contrast to the vast amount of active research and available knowledge on many aspects of protein-calorie malnutrition, surprisingly little attention has been focused on the skeletal effects of this syndrome. As early as the 1920's it was realised that the skeletal metabolism in protein-calorie malnutrition was deranged. Notwithstanding this, there is still to date inadequate understanding of the mechanisms by which these skeletal changes are brought about. This is partly due to the fact that the research workers were "victims of their times" in that the techniques utilised gave limited information and it has only been in the past decade or two that more sophisticated techniques have become available. (Evidence for this will be borne out in the following chapter where the literature is reviewed). It was with this in mind that the work presented in this thesis was undertaken. Part I of the thesis consists of a review of the literature, followed by a dissertation on the normal physiological concepts of calcium metabolism as well as a description of the calcium pools used in kinetic models. Part II includes all the chapters on the various experiments performed. Included in each chapter are the methods used, results obtained as well as a discourse relevant to that particular study, with special reference to similar experiments performed by other authors. Part III encompasses the integrated summary of the results and a discussion theorising the mechanisms involved in those changes. Finally, an appendix which deals with the statistical methods used for analyses, as well as details of those techniques which were used, but were established by other authors.

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Abstract Dietary xylitol supplementation increases bone calcium and phosphorus concentrations in healthy rats, as well as protects against the decrease of bone minerals and bone density during experimental osteoporosis. This suggests that dietary xylitol might have a favorable effect on the prevention of osteoporosis. However, before any conclusions can be drawn about the usefulness of a compound, studies including structural evaluation and biomechanical testing of bones must first be performed. Thus, the aim of the present study was to clarify whether dietary xylitol affects bone resorption, bone structure, and bone biomechanics in healthy rats, and whether dietary xylitol offers some preventive effects against the increased bone resorption, decreased bone trabeculation, and weakened bone biomechanical properties during experimental osteoporosis. Dietary xylitol reduced bone resorption in 3-mo old healthy male rats, and protected significantly against the increase of bone resorption in 3-mo old ovariectomized rats, as measured by the urinary excretion of 3H following [3H]tetracycline-prelabeling. In addition, increased trabecular bone volume of proximal tibia in 4-mo old healthy male rats was detected after a 1-mo xylitol feeding period, and significant protection against the decrease of trabecular bone volume in 6-mo old ovariectomized rats was observed after a 3-mo xylitol feeding period. Furthermore, dietary xylitol increased the strength properties of long bones in 6-mo old healthy male rats after a 3-mo feeding period, without affecting the bone elastic properties as tested by three-point bending of tibia, torsion of femur, and loading of femoral neck. Accordingly, dietary xylitol protected significantly against the weakening of bone biomechanical properties in 6-mo old ovariectomized rats after a 3-mo feeding period. In conclusion, the above results strongly support the hypothesis that oral administration of xylitol protects effectively against the progression of experimental osteoporosis. Dietary xylitol was effective both in increasing bone mass in healthy rats, and in preventing bone loss in ovariectomized rats, suggesting a favorable effect of xylitol on both main targets in the prevention of osteoporosis. As dietary xylitol was effective also in protecting against the experimental osteoporosis-caused changes in bone structure and weakening of bone biomechanical properties, oral xylitol administration seems to provide interesting possibilities when searching for new physiological choices for the prevention of osteoporosis.

Dans le contexte actuel d’allongement de l’espérance de vie, la prévalence des maladies liées à l’âge telles que l’ostéoporose est de plus en plus importante. Le coût de la prise en charge de ces pathologies constitue un problème de santé public majeur et la mise en place de stratégies de prévention nutritionnelle adaptées apparaît comme une excellente solution alternative aux traitements habituels. Pourtant, l’étude des activités biologiques des nutriments reste trop marginale pour certains tissus et certaines catégories de molécules, c’est notamment le cas du tissu osseux et des lipides, en particulier les acides gras.Ces derniers sont pourtant capables de moduler le devenir du tissu osseux que ce soit indirectement par des mécanismes systémiques ou directement au niveau de la cellule osseuse. La perte osseuse liée au vieillissement est souvent associée à l’établissement progressif d’une inflammation chronique à bas bruit à l’échelle de l’organisme. Dans ce contexte, les niveaux de cytokines pro-inflammatoires telles que l’interleukine 6 ou le Tumor Necrosis Factor α sont augmentés et ces composés, qui sont connus pour induire la résorption osseuse, pourraient contribuer à la dégradation du squelette. Notre hypothèse de travail était que certains Acides Gras Poly-Insaturés (AGPI) à propriétés anti-inflammatoires pouvaient éventuellement limiter l’inflammation chronique associée au vieillissement et ainsi contribuer à préserver le capital osseux. Dans cette optique, nous avons utilisé la souris SamP8 qui est un modèle de progeria présentant, à douze mois, un phénotype ostéoporotique. Dans ce modèle, l’administration d’un régime délétère à base d’huile de tournesol (ratio acide gras ω6 /ω3 très important) aggrave la perte osseuse en association avec une augmentation des marqueurs inflammatoires systémiques et osseux ainsi qu’une augmentation des marqueurs de la résorption osseuse. La supplémentation de ce régime tournesol avec de l’huile de bourrache ou de l’huile de poisson permet d’apporter des quantités importantes d’AGPI anti-inflammatoires (acide γ-linoléique pour l’huile de bourrache et ω3 pour l’huile de poisson). De manière intéressante, ces deux régimes supplémentés permettent, en plus de réduire les paramètres inflammatoires, de s’opposer à l’augmentation des marqueurs de résorption osseuse et de limiter la diminution de la densité minérale de l’os chez ces souris. Cette étude met donc en évidence le potentiel santé de certains AGPI au regard de la préservation du capital osseux et suggère un rôle déterminant de leurs propriétés anti-inflammatoires systémiques. En parallèle, la description des effets directs des acides gras au niveau cellulaire par l’activation de récepteurs spécifiques occupent une place croissante dans la littérature. Récemment, le récepteur membranaire GPR40 (G Protein coupled Receptor 40) a été mis en évidence pour ses interactions avec les acides gras libres à longues chaînes et nous avons pu montrer son expression dans les précurseurs ostéoclastiques. Nous avons donc émis l’hypothèse que ce récepteur pourrait jouer un rôle dans la médiation des effets des acides gras sur les paramètres du remodelage osseux. Ce travail a permis de mettre en évidence l’existence d’un phénotype ostéoporotique chez la souris invalidée pour le GPR40. L’effet protecteur de ce récepteur semble lié principalement à un effet inhibiteur de son activation sur la différenciation des ostéoclastes. En effet, l’utilisation de l’agoniste spécifique du GPR40 empêche in vitro la différenciation ostéoclastique par RANKL de deux modèles cellulaires de manière GPR40-dépendante. De surcroit, cet agoniste est également capable in vivo de s’opposer à une perte osseuse induite chez la souris. Ces résultats révèlent pour la première fois l’implication du récepteur GPR40 dans la physiologie osseuse et apportent la connaissance d’une nouvelle possibilité de modulation directe des cellules osseuses par les acides gras. / With increasing lifespan, prevalence of age-related complications has grown including skeletal defects such as osteoporosis. Socio-economic consequences of these disorders represent a major public health problem worldwide and in this context, nutritional prevention strategies may be considered as a good option to be associated with usual therapies. However, biological activities of some nutrients have been too poorly deciphered in regards to their bone health potential. This is notably true concerning fatty acids and both their direct and indirect relationships with the skeleton. Age-related bone complications are often associated with a gradual establishment of a systemic low-grade inflammatory condition. This leads to high levels of pro-inflammatory cytokines such as interleukin 6 or tumor necrosis factor α which are known to favour osteoclast-induced bone resorption. Then, these high pro-inflammatory cytokines levels may contribute to age associated bone loss. We hypothesize that in this context, poly-unsaturated fatty acids (PUFA) with known anti-inflammatory properties may counteract both the low-grade inflammation establishment and the associated bone loss. Thus, animals from the progeria mouse model SamP8 were used and were shown to exhibit osteoporosis at twelve months. Feeding these mice with a deletary (very high ω6/ω3 ratio) sunflower oil-based diet results in an exacerbated bone loss, associated with increased systemic and bone inflammation parameters as well as increased bone resorption markers. Either borage or fish oil supplementation of the sunflower oil-based diet result in high amounts of anti-inflammatory PUFAs in the diet (γ-linoleic acid with borage oil and ω3 with fish oil). Interestingly, mice fed with the two “supplemented” diets show reduced inflammatory parameters but also reduced levels of bone resorption markers and preserved bone mineral density. In this work, the bone health potential of some PUFAs was established and was linked to their systemic anti-inflammatory properties. Besides, fatty acids are increasingly studied as signalling molecules, able to modulate cell signalling by their interactions with specific receptors. A few years ago, long chain fatty acids were shown to be ligands of the membrane bound fatty acid receptor GPR40 (G Protein coupled Receptor 40). As we showed GPR40 expression in osteoclast precursors, we hypothesized that it may be involved in fatty acid-induced bone remodelling regulation. In this study, an osteoporotic phenotype was found in GPR40-deficient mice. This GPR40- mediated bone protection seems to involve an anti-osteoclastogenic effect. As a matter of fact, a GPR40 specific agonist led to blunted RANKL-induced osteoclastic differentiation in a GPR40-dependant way. In addition, this agonist was also able in vivo to counteract ovariectomy-induced bone loss in mice. Thus, involvement of GPR40 in bone remodelling was established for the first time in this work, bringing to light a new mechanism in the fatty acid-induced modulation of bone metabolism.

Orientador: Célia Regina Nogueira / Resumo: O sistema esquelético é um sistema complexo com intenso metabolismo composto de células, proteínas e minerais. Os osteoblastos, são células fundamentais para o tecido, desempenhando duas funções principais: formação óssea e regulação da reabsorção por meio da modulação da osteoclastogênese. Sendo assim, essas células desempenham funções primordiais para o desenvolvimento e manutenção óssea. Diversas moléculas sistêmicas atuam no tecido, sendo os hormônios tireoidianos um destes. Eles são fundamentais para o metabolismo ósseo já que alterações hormonais culminam em desordens ósseas. Osteoblastos possuem receptores nucleares para T3 e apesar de pouco compreendido, ele afeta diversos aspectos do desenvolvimento da célula, assim como vias modulatórias da remodelação óssea. Diversas linhagens celulares têm sido utilizadas para estudos de osteoblastos, sendo as células-tronco mesenquimais derivadas do tecido adiposo humano (hA-CTMs) um modelo promissor para osteoindução. Desta forma, o objetivo deste trabalho foi verificar a influência do T3 suprafisiológico (T3S) na expressão gênica diferencial em osteoblastos diferenciados a partir de hA-CTMs. As células obtidas de 3 doadores foram submetidas a osteoindução por 16 dias com coquetel de diferenciação (dexametasona, ácido ascórbico e β-glicerofosfato) e caracterizadas pela presença de osteocalcina, fosfatase alcalina e matriz mineralizada. O tratamento com T3 (10-8M) foi realizado por 72h e o RNA foi extraído para preparação das bib... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The skeletal system is complex and have an intense metabolism compound with cells, proteins and minerals. The osteoblasts are fundamental cells to the tissue, executing two mainly functions: bone formation and regulation of reabsorption through osteoclastogenesis modulation. Therefore, these cells perform primordial functions to the bone development and maintenance. Several systemic molecules act in the tissue and the thyroid hormones are one of them. They are fundamental to the bone metabolism, once hormone alterations result in bone disorders. Osteoblasts have T3 nuclear receptors, and although not well elucidated it affects many aspects of the cell development so as pathways that modulates the bone remodeling. Several cells lineages have been used in osteoblasts studies, and human adipose-derived Mesenchymal stem-cells (hA-MSCs) are a promising model to osteoinduction. Thus, the aim of this study was to investigate the supraphysiological T3 (T3S) influence in the gene differential expression in osteoblasts differentiated from hA-MSCs. The cells obtained from three donators were submitted to osteoinduction for 16 days with a differentiation cocktail (dexamethasone, ascorbic acid, β-glycerophosphate) and characterized by the presence of osteocalcin, alkaline phosphate and mineralized matrix. The cells were treated with T3 (10-8M) for 72h and the RNA was extracted to mRNA library prepare and sequenced by Illumina platform. The bioinformatic analysis included the software: Fas... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:31:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-12Bitstream added on 2014-06-13T19:41:12Z : No. of bitstreams: 1 cardoso_mjl_dr_botfmvz.pdf: 248290 bytes, checksum: 9109a7b559aa1fe60811340d1a417214 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os efeitos do hipertireoidismo experimental (150 g/kg/dia/42 dias) na homeostase do cálcio e nos marcadores do metabolismo ósseo foram estudados em 14 gatos sem raça definida, com idade entre um e três anos. Houve uma clara tendência de aumento das concentrações séricas de PTH intacto a partir do momento inicial com diferença significativa entre este e os demais momentos. O cálcio ionizado demonstrou uma diminuição significativa aos 14 dias em relação ao momento inicial e aos 42 dias em relação aos 14 dias. Os hormônios tireoidianos apresentaram correlação positiva com o PTH e negativa com o cálcio ionizado. Já a densidade mineral óssea (DMO) apresentou tendência de correlação negativa com o PTH a partir dos 28 dias. Observou-se correlação negativa do PTH com o cálcio ionizado aos 14, 28 e 42 dias. Conclui-se que o hipertireoidismo em gatos adultos jovens sem doenças concomitantes apresenta hiperparatireoidismo secundário. As concentrações séricas da OC apresentaram diferença significativa (p<0,05) entre si, nos quatro momentos. O ICTP, um marcador específico da reabsorção óssea, não apresentou diferença significativa entre os momentos. Provavelmente o remodelamento ósseo foi provocado pelo estado hipertireóideo, visto que tanto a OC como o ICTP apresentou forte correlação positiva com a TT4 e um pouco inferior com a FT4. A FT4 não apresentou correlação positiva com o ICTP, excetuando-se aos 28 dias. Observou-se baixa correlação, em todos os momentos, entre os marcadores do metabolismo ósseo e a densidade mineral óssea. Conclui-se que o excesso dos hormônios tireoidianos em gatos provocou aumento do remodelamento ósseo visto que ocorreu alta correlação entre estes hormônios e os marcadores do metabolismo ósseo. O hipertireoidismo provocou diminuição da DMO óssea, porém a OC e o ICTP apresentaram baixa correlação com esta variável. / The effect of experimental hyperthyroidism (150 g/kg/day/42 days) on calcium homeostasis and markers of bone metabolism was studied in fourteen shorthair cats from one to three years of age. Serum concentrations of unbroken PTH had a clear tendency to increase from beginning with significant differences from the initial to other moments. The ionized calcium significantly decreased at the 14 days in comparison to the initial moment and at the 42 days in comparison to the 14 days. The thyroid hormones showed positive correlation with PTH and negative with ionized calcium. In contrast, bone mineral density had a tendency of negative correlation with the PTH from the 28 days. Negative correlation of the PTH and calcium ionized was observed at 14, 28 and 42 days. In the present study, hyperthyroidism in young adult cats without concomitant illnesses did not present secondary hyperparathyroidism. However, increase of PTH and reduction of ionized calcium were observed. Serum concentrations of osteocalcin (OC) were significantly different among all four moments. The carboxi-terminal telopeptides of collagen type I (ICTP), a specific marker of the bone reabsorption, did not significantly differ (p<0.05) between moments. Bone turnover was probably caused by the hyperthyroid state, since OC and ICTP presented strong positive correlation with TT4 and a little less with free T4 (FT4). The FT4 did not present positive correlation with the ICTP, excepting at the 28 days. Positive correlation in all the moments between markers of bone metabolism and bone mineral density was very low. In conclusion, the high correlation between thyroid hormones and markers of bone metabolism indicates that the excess of thyroid hormones in cats may cause an increase of the bone turnover. Moreover, hyperthyroidism may cause reduction of the bone DMO, although OC and the ICTP had low correlation with DMO.

Orientador: Mario Roberto Marostica Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-14T12:39:16Z (GMT). No. of bitstreams: 1 Netto_ClaudiaCardoso_D.pdf: 2053109 bytes, checksum: cc5fdf0563fa6ad34d6e60af9b0a023c (MD5) Previous issue date: 2009 / Resumo: Prebióticos são oligossacarídeos não digeríveis (ONDs) seletivamente fermentados pelas bactérias intestinais e agem como agentes bifidogênicos melhorando a saúde e o bem estar do hospedeiro. Os átomos de carbono das moléculas de hexosil fermentados são transformados em ácidos graxos de cadeias curtas (AGCC) e, uma vez absorvidos na mucosa intestinal, estes são metabolizados pelos enterócitos, células hepáticas e musculares. O interesse primário em relação aos AGCC tem sido relacionado à sua função colônica, especialmente o butirato. Porém, esses AGCC também estão relacionados a outros benefícios em relação a saúde do hospedeiro, como por exemplo, podem aumentar a absorção intestinal de minerais e conseqüentemente reduzir a perda de massa óssea. Como a perda de massa óssea é um processo fisiológico associado ao envelhecimento animal, o objetivo deste trabalho foi avaliar se ratas idosas com 10 (dez) meses de idade suplementadas com diferentes tipos de prebióticos (fructooligossacarídeos, inulina e galactooligossacarídeos) apresentavam redução dessa perda de massa óssea. Foram realizadas as seguintes análises: densitometria óssea (DXA) do fêmur e mandíbula; morfometria e propriedades biomecânicas do fêmur; parâmetros estáticos da histomorfometria e microscopia eletrônica de varredura da epífise proximal da tíbia; dosagem sérica de hormônio da paratireóide (PTH), osteocalcina (OC), osteoprotegerina (OPG), fator receptor ativador nuclear ?appa B ligante(RANk-L), fragmentos de colágeno tipo I (CTX-I), atividade da fosfatase alcalina (FA) total e cálcio total. Os resultados foram analisados em ANOVA (p<0,05) através do software GraphPad versão 6.0 e as diferenças estatísticas determinadas através do teste de Tukey ou t de Student. Todos os protocolos experimentais foram aprovados pelo Comitê de Ética para Experimentação Animal da Universidade Estadual de Campinas. Os experimentos foram iniciados com ratas Wistar de dez meses de idade, visto que estas apresentaram alterações significativas no metabolismo ósseo associadas à idade quanto comparadas às ratas jovens, como por exemplo, aumento no nível sérico de PTH. O consumo de prebióticos promoveu a redução da perda de massa óssea fisiológica associada ao envelhecimento, porém, outros estudos precisam ser realizados com a finalidade de descrever os mecanismos de ação / Abstract: Prebiotics are non-digestible oligosaccharides (NDO) selectively fermented by intestinal bacteria that are bifidogenic agents with health benefit on the host associated. The carbon atoms of the fermented hexosyl moiety are recovered in the short-chain fatty acids (SCFA) and once absorbed, they are metabolized by cells of cecocolonic epithelium, liver cells and muscle cells. The primary interest in SCFA has been related with colonic function as a result of their uptake and metabolism by colonocytes, specifically butyrate. Although, SCFA are also described with other benefits properties as improving intestinal mineral absorption and consequently reducing bone loss. As bone loss during later life is a physiologic mechanism, the objective of this study was to evaluate if different kinds of prebiotics attenuate age related bone loss in female rats. Old female rats (10 month-old) were treated with different kinds of prebiotics (Fructooligosaccharides, Inulin and Galactooligosaccharides). Femur and mandible bone mass was measured using dual-energy X-ray absorptiometry. Femur quality was examined using morphometry and diaphysis biomechanic properties (proportional limit, rupture limit, resilience, rigidy and tenacity) using three-point bending. Histomorphometry static parameters and scanning electron microscopy images were taken on tibiae methaphysis cancellous bone. The biochemical assays were serum parathyroid hormone (PTH), osteocalcin (OC), osteoprotegerin (OPG), receptor activator for nuclear factor ?appa B ligand (RANk-L), C-terminal peptides of type I collagen (CTXI), alkaline phosphate activity (ALP) and total calcium. All data were analyzed by twoway ANOVA (p<0,05) using GraphPad software version 6.0 and the significant differences were determined with Tukey¿s test or Student t-test. All the protocol experimental designs were approved by Animal Experimental Ethics Committee of the University of Campinas. Our experimental were taken with aged female Wistar rats that showed a satisfactory model to evaluate age related changes on bone metabolism as well as to study osteoporosis and their mechanisms. The consumption of prebiotics preserved bone mass and reduced bone turnover. Despite our prebiotics results had been positive, more studies are required to establish mechanisms of action / Doutorado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Doutor em Alimentos e Nutrição

Patients with Graves´ Disease (GD) have a higher risk of developing more severe and prolonged hypocalcaemia after total thyroidectomy (TT) than patients who undergo surgery for benign atoxic goitre. Since TT is the most effective treatment for GD, it is crucial to identify mechanisms for postoperative hypocalcaemia. The aim of this thesis was to study the mechanisms of calcium metabolism in patients with GD. It is safe to operate on GD patients with TT. Results in Paper I showed fewer recurrences and equal complication rates compared to patients who underwent subtotal thyroidectomy (ST). The transient lowering of PTH seen in the hypocalcaemic patients was fully restored one month after surgery (Papers II and V). The calcium-sensing receptor (CaSR) is crucial for maintaining plasma calcium, and single nucleotide polymorphisms (SNPs) in the gene may alter the sensing function. Thus, we analysed SNPs in CaSR in GD patients (Paper II) and showed that they had a more left-shifted calcium-PTH set-point compared to controls, implicating higher sensitivity. This is also supported by the results in the group of postoperatively hypocalcaemic patients. They already had lower plasma calcium preoperatively (Papers II, IV and V) and lacked the T/G G/A G/C, a haplotype shown in Paper III to have a close relationship to higher p-calcium levels. Moreover, a lack of the T allele in rs1801725 was seen in the group of patients needing permanent treatment with calcium and vitamin D, i.e. &gt; 12 months, (paper V). Patients who became hypocalcaemic (p-calcium &lt; 2.00 mmol/L) on day one postoperatively, had lower preoperative levels of thyroid stimulating hormone (TSH) and higher levels of  T3, this was also applied to the patient groups requiring temporary or permanent postoperative treatment (Papers II and V). In addition, hypocalcaemic patients treated for less than six months with anti-thyroid drugs had higher levels of bone metabolism markers CTX and P1NP than normocalcaemic patients (Paper V). In conclusion, the postoperative period of hypocalcaemia seen in patients with GD is a complex medical condition, caused by a combination of surgical trauma, different SNPs in CaSR, and high bone metabolism related to preoperative thyroid metabolism.