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No description available.

Estimation of age is a crucial step for the identification of unknown individuals. Age is commonly assessed through macroscopic analytical methods based on the gross-examination of age degenerative changes in the skeleton. The choice of the methods relies on the taphonomic condition of the human remains and/or the skeletal element that is available. In cases of very fragmented bones, microscopic techniques remain one of the few approaches to estimate age. Thus, many histological age estimation methods have been developed for different bones and on different samples in the last forty years. Numerous intrinsic and extrinsic factors influence bone remodelling rates and have shown to affect the accuracy of histological aging methods. The present study investigates rib thin-sections from two Mediterranean samples, aiming to explore the applicability and reliability of histological methods in estimating age within these samples. Standard ribs were obtained from males and females (N = 88, Mean age = 60, SD = 17.90) from two samples, Cretans (Greece) and Greek- Cypriots (Republic of Cyprus). The costal elements were processed histologically according to standard protocols and thirteen raw and composite histomorphometric parameters (frequency number of intact and fragmentary osteons, total osteons, osteon population densities - including OPD(I) and OPD(F) - cortical area, total area, endosteal area, relative cortical area, osteon area, osteon perimeter and osteon circularity) were assessed. Intra- and inter-observer errors were examined. Due to the fragmented nature of the costal elements, sampling error was calculated as a means to explore whether the histological variables vary among six different topographical locations along the rib length. A validation study was carried out by applying four existing histological age prediction equations on the entire dataset and on the sub-datasets (sex and samples separately) in order to verify whether population-specific formulae are required for the Mediterranean samples. The relationship between the histological variables and age, as well as sex and samples, was determined through several statistical tests. Lastly, simple and multiple regression analyses were performed testing all possible combinations of variables. The best models ii were finally selected according to prediction power and goodness of fit indicators. The results from intra- and inter-observer errors indicated that most of the histological parameters achieved high levels of repeatability. The preliminary outcome from the sampling error pilot study suggested low variability among the six thin-sections from each rib. According to the validation study, three of the four age prediction equations resulted in high underestimation of age, indicating that population-specific formulae are needed to provide more accurate age estimates. Most of the histological variables showed a statistically significant correlation with age with some differences observed by sex and by sample. Forty-one models were generated concluding that osteon densities along with rib and osteon measurements formulae produced the most accurate results. The best model generated from the entire dataset included OPD and osteon circularity with a standard error of the estimate of 10.45 years. When sex and samples were separated, the best model selected included OPD and osteon perimeter producing a standard error of the estimate of 8 years for Cypriots. This research demonstrates that quantitative bone histology is a feasible method to estimate age on the Mediterranean samples obtaining errors rates that are in accordance with macroscopic ageing techniques. Inter-population variation in remodeling rates is suggested; however, the inclusion of other bones presenting different remodelling dynamics (such as femora) is recommended to further explore this hypothesis. This study contributes to the creation of population-specific standards for Cretans and Cypriots.

Made available in DSpace on 2014-06-11T19:30:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-04-18Bitstream added on 2014-06-13T21:01:52Z : No. of bitstreams: 1 almeida_jd_dr_sjc.pdf: 798214 bytes, checksum: 01a38ab886a92b48594e6df7a458da16 (MD5) / Neste trabalho foi realizado estudo comparativo dos efeitos da calcitonina e do Plumbum mettalicum 30CH na reparação óssea guiada em mandíbulas de ratos. Foram utilizados 75 ratos com idade aproximada de três meses, que foram divididos em grupo controle, tratado com calcitonina e tratado com Plumbum mettalicum 30CH, com 25 animais cada. Todos os ratos foram submetidos à cirurgia para realização de defeito ósseo na região de ângulo de mandíbula de aproximadamente 4mm, o qual foi recoberto por uma barreira de politetrafluoretileno. Após a cirurgia, o grupo tratado com calcitonina passou a receber 2 UI/kg, i.m., três vezes por semana, e o grupo tratado com Plumbum mettalicum 30CH, três gotas diluídas em água diariamente. Os animais foram sacrificados em períodos de três, sete, 14, 21 e 28 dias, sendo suas mandíbulas removidas e encaminhadas para preparação histológica. Análises densitométrica, histológica e histomorfométrica foram realizadas. Para análise estatística, utilizou-se ANOVA, teste de Tukey e teste de Scheffé ao nível de 5%. A análise densitométrica mostrou menor densidade óptica no grupo controle em todos os períodos analisados. Foi observado o preenchimento total do defeito por tecido ósseo neoformado apenas no grupo tratado com homeopatia, aos 28 dias. Nos demais grupos não foi observada união das bordas do defeito. Na análise histomorfométrica não se encontrou diferença estatística entre os grupos tratados e controle, porém o grupo tratado com Plumbum mettalicum 30CH apresentou melhores resultados que o tratado com calcitonina. Concluiu-se que, nas condições utilizadas, a reparação óssea guiada de defeitos em mandíbulas de ratos machos é favorecida pelo Plumbum mettalicum 30CH , mas não pela calcitonina. / The purpose of this work was to compare the effects of calcitonin and Plumbum mettalicum 30CH on guided mandibular bone repair of male rats. We analyzed the mandible of 75 rats, approximately three months old, which were divided into control group, group treated with calcitonin and group treated with Plumbum mettalicum 30CH. Each group was composed by 25 animals. A circumscribed bone defect of 4mm diameter was prepared in the mandibular bone, in the angle region. The defect was covered with a PTFE barrier in all animals. The group treated with calcitonin received 2UI/Kg i.m. three times a week and the group treated with homeopathy received three drops diluted in the water every day. Both treated groups began immediately after surgery. The animals were sacrificed after three, seven, 14, 21 and 28 days. Their mandibles were removed, and after routine histological processing they were submitted to densitometric, histological and histomorphometrical analysis. For statistical analysis, ANOVA, Tukey and Scheffé tests (p<0,05) were used. The densitometric analysis showed lower optical density in the group control than in the others, at all periods. Only in the group treated with Plumbum mettalicum 30CH, the defects were completely healed at the final observation period. The histomorphometrical analysis showed no statistical difference between control, calcitonin and homeopathy treated groups, however the last one had better results than the one treated with calcitonin. It was concluded that, in circumscribed mandibular defects in male rats, Plumbum mettalicum 30CH induces better bone repair than calcitonin.

Human exposure to reduced weightbearing results in bone loss. The rate of bone loss during microgravity exposure is similar to that of a post-menopausal women. In fact, the maintenance of bone mass is intimately dependent on exercise. Therefore, exercise associated mechanical loads to bone tissue are an important countermeasure to prevent disuse-induced bone loss. However, the types of exercise modalities required to prevent such bone loss are unclear. Moreover, how mechanical loading to bone translates into molecular osteogenic signals in bone cells is unknown. Radiation exposure is another potent inducer of bone loss, namely observed on Earth in the clinical setting following radiotherapy procedures. It is expected that long duration space missions outside the protection of Earth’s magnetosphere will result in significant galactic cosmic radiation exposure. However, the magnitude of bone loss resulting from this galactic cosmic radiation exposure is unclear. Moreover, it is unknown if radiation exposure will exacerbate disuse-induced bone loss. Therefore, a series of experiments were designed to determine: 1) Will simulated galactic cosmic radiation exacerbate reduced weightbearing-induced bone loss? 2) Will pharmacological activation of the putative mechanosensing Wnt pathway enhance exercise-induced bone mass gain? To address these questions the experimental study series employed two animal models of reduced weightbearing, hindlimb unloading and partial weightbearing. These model test-beds enabled the evaluation of two novel countermeasures (simulated resistance exercise and glycogen synthase kinase-3 (GSK-3) therapeutic) and simulated exposure to space radiation environments. To test the impact of simulated space radiation (28Si) one study of the series was conducted at Brookhaven National Laboratory. To quantify the impact of the abovementioned countermeasures and space radiation on bone, mechanical testing, peripheral quantitative computed tomography, micro-computed tomography, histomorphometry, and immunohistochemistry served as primary outcome measures. The primary findings are: 1) Low-dose high-LET radiation negativity impacts maintenance of bone mass by lowering bone formation and increasing bone resorption. This impaired bone formation response is in part due to sclerostin induced suppression of Wnt signaling. 2) Combining GSK-3 inhibition with high intensity exercise mitigates cancellous bone loss and restores cortical periosteal growth during disuse.

Mechanical loading is an integral component to maintaining bone mass during periods of disuse (i.e. bedrest or casting) or reduced weightbearing activity. Recent data has shown a direct relation between the sympathetic nervous system (SNS) and bone metabolism, however the underlying mechanisms responsible for this relationship are unknown. Furthermore, the role that beta adrenergic stimulation during disuse has on cancellous bone mass and microarchitecture have yet to be defined. The central hypothesis of this research is that resistance exercise and beta-1 adrenergic (Adrb1) receptor agonist administration attenuate disuse-associated reductions in metaphyseal bone during 28 days of rodent hindlimb unloading (HU). Study one determined whether an eccentric- (ECC) or combined isometric+eccentric- (ISO+ECC) based contraction paradigm, engaged during hindlimb unloading (HU), mitigates losses in musculoskeletal mass and strength. Both simulated resistance training (SRT) protocols inhibited reductions in disuse-sensitive cancellous bone mass and maintained plantarflexor muscle strength. Study two determined whether combining the anabolic effects of SRT with the anti-resorptive effects of alendronate (ALEN) during HU positively impacts cancellous bone in an additive or synergistic fashion. ALEN significantly inhibited the anabolic response of cancellous bone to SRT during HU. Study three determined whether an Adrb1 receptor agonist (dobutamine; DOB) mitigates disuse-associated losses in bone mass and formation rate (BFR) during HU. DOB administration significantly blunted reductions in bone mineral density (vBMD) by maintaining cancellous BFR. Study four determined if Adrb1 receptor agonist administration during HU results in an attenuation of osteocyte apoptosis within cancellous bone and whether this relates to a decrease in Bax/Bcl-2 mRNA content ratio (pro- and anti-apoptotic proteins). HU significantly increased cancellous bone osteocyte apoptosis and Bax/Bcl-2 mRNA content ratio, which was reduced by the administration of DOB. Collectively, these are the first studies to assess the role of beta-1 adrenergic signaling and resistance exercise in mitigating disuse-induced loss of cancellous bone mass in rodents. The long term goals of this research are to understand the exact molecular mechanisms by which both Adrb1 signaling and high intensity resistance exercise provide beneficial bone effects during prolonged periods of disuse and to apply these findings to current osteoporosis research.

Resumo: Diversas situações provocam alterações significativas na estrutura óssea, tais como a permanência de astronautas no espaço, imobilizações ortopédicas e permanência prolongada de pacientes em leito. A atividade física é contra medida para a recuperação dessas alterações causadas no sistema ósseo. O objetivo deste estudo foi avaliar a influência da suspensão, do treinamento físico e da movimentação livre, através de análises biomecânicas, densitométricas e histomorfométricas em terço médio de fêmures de ratos. Foram utilizados setenta e cinco ratos machos, distribuídos em cinco grupos experimentais. Destes, dois utilizados como controle CI (21 dias) e CII (42 dias) e três suspensos por 21 dias. Dos suspensos um foi sacrificado logo após a suspensão, S, outro foi submetido a período de atividade física em esteira por 21 dias, SE, e o terceiro à movimentação livre por 21 dias, SL. A análise biomecânica não expressou diferenças significativas nos grupos SE e SL em nenhum dos parâmetros analisados (Força Máxima, Rigidez e Resiliência), já o grupo S apresentou redução significativas em todas as propriedades mecânicas estudadas. Na análise de densidade óssea, pelo Principio de Arquimedes, encontrou-se diferença significativa entre o grupo S e CI e em relação aos grupos SE e SL. Ocorreu diferença entre o grupo SE e SL. Na densidade óssea, pela Densitometria Radiográfica, o grupo S diferiu do CI, SE e SL e não ocorreu diferença entre os grupos SE e SL. A espessura óssea compacta pela análise histomorfométrica não sugeriu diferença significativa entre os grupos analisados. A suspensão de ratos pela cauda provocou reduções importantes nos valores de propriedades mecânicas e densitométricas do osso, o treinamento físico em esteira foi mais eficiente que a movimentação livre apenas na variável de densidade óssea pelo Princípio de Arquimedes. / Abstract: Different situations provoke significant alterations in bone structure. The permanence of astronauts in the space, orthopedics immobilizations and drawn out permanence of patients in stream bed. The physical activity is against measure for the recovery of these alterations caused in the bone system. The objective of this study was to evaluate the influence of the suspension, the physical training and the released movement, through biomechanical, densitometry and histomorphometry analyses in mid third of femurs of rats. Seventy-five male rats were used, distributed in five experimental groups. Of these, two were used as control CI (21 days) and CII (42 days) three were suspended by 21 days. One of the suspended groups, S, was sacrificed soon after suspension, other one was submitted to 21 days treadmill physical exercise, SE, and the third group was submitted to 21 days released walking, SL. The biomechanical analysis did not express significant differences in SE and SL groups in none of the analyzed parameters (Maximum Force, Rigidity and Resilience), the S group presented significant reduction in all the mechanical properties analyzed. In the bone density analysis by Archimedes method, significant difference between group S and CI and in relation to groups SE and SL were found. Differences between group SE and SL occurred. In bone density, by Radiographic Densitometry, group S differed from the CI, SE and SL and did not occur difference between SE and SL groups. The histomorphometry analyses had not suggested significant differences between the analyzed groups. The suspension of rats by the tail provoked important reductions in the values of mechanical properties and densitometry of the bone tissue, the treadmill physical training was more efficient than the released walking only in the variable of bone density by Archimedes Method. / Orientador: Mário Jefferson Quirino Louzada / Coorientador: Luciana Del Rio Pinoti Ciarlini / Banca: Keico Okino Nonaka / Banca: João Cesar Bedran de Castro / Mestre

Orientador: Yasmin Rodarte Carvalho / Banca: Yasmin Rodarte Carvalho / Banca: Darcy de Oliveira Tosello / Banca: Suzana Cantanhede Orsini Machado de Sousa / Banca: Rosilene Fernandes da Rocha / Banca: Luiz Antonio Guimarães Cabral / Resumo: Neste trabalho foi realizado estudo comparativo dos efeitos da calcitonina e do Plumbum mettalicum 30CH na reparação óssea guiada em mandíbulas de ratos. Foram utilizados 75 ratos com idade aproximada de três meses, que foram divididos em grupo controle, tratado com calcitonina e tratado com Plumbum mettalicum 30CH, com 25 animais cada. Todos os ratos foram submetidos à cirurgia para realização de defeito ósseo na região de ângulo de mandíbula de aproximadamente 4mm, o qual foi recoberto por uma barreira de politetrafluoretileno. Após a cirurgia, o grupo tratado com calcitonina passou a receber 2 UI/kg, i.m., três vezes por semana, e o grupo tratado com Plumbum mettalicum 30CH, três gotas diluídas em água diariamente. Os animais foram sacrificados em períodos de três, sete, 14, 21 e 28 dias, sendo suas mandíbulas removidas e encaminhadas para preparação histológica. Análises densitométrica, histológica e histomorfométrica foram realizadas. Para análise estatística, utilizou-se ANOVA, teste de Tukey e teste de Scheffé ao nível de 5%. A análise densitométrica mostrou menor densidade óptica no grupo controle em todos os períodos analisados. Foi observado o preenchimento total do defeito por tecido ósseo neoformado apenas no grupo tratado com homeopatia, aos 28 dias. Nos demais grupos não foi observada união das bordas do defeito. Na análise histomorfométrica não se encontrou diferença estatística entre os grupos tratados e controle, porém o grupo tratado com Plumbum mettalicum 30CH apresentou melhores resultados que o tratado com calcitonina. Concluiu-se que, nas condições utilizadas, a reparação óssea guiada de defeitos em mandíbulas de ratos machos é favorecida pelo Plumbum mettalicum 30CH , mas não pela calcitonina. / Abstract: The purpose of this work was to compare the effects of calcitonin and Plumbum mettalicum 30CH on guided mandibular bone repair of male rats. We analyzed the mandible of 75 rats, approximately three months old, which were divided into control group, group treated with calcitonin and group treated with Plumbum mettalicum 30CH. Each group was composed by 25 animals. A circumscribed bone defect of 4mm diameter was prepared in the mandibular bone, in the angle region. The defect was covered with a PTFE barrier in all animals. The group treated with calcitonin received 2UI/Kg i.m. three times a week and the group treated with homeopathy received three drops diluted in the water every day. Both treated groups began immediately after surgery. The animals were sacrificed after three, seven, 14, 21 and 28 days. Their mandibles were removed, and after routine histological processing they were submitted to densitometric, histological and histomorphometrical analysis. For statistical analysis, ANOVA, Tukey and Scheffé tests (p<0,05) were used. The densitometric analysis showed lower optical density in the group control than in the others, at all periods. Only in the group treated with Plumbum mettalicum 30CH, the defects were completely healed at the final observation period. The histomorphometrical analysis showed no statistical difference between control, calcitonin and homeopathy treated groups, however the last one had better results than the one treated with calcitonin. It was concluded that, in circumscribed mandibular defects in male rats, Plumbum mettalicum 30CH induces better bone repair than calcitonin. / Doutor

No description available.