[Truncated abstract] Bone is a living tissue and is maintained by the coordinate action of osteoblasts and osteoclasts. The intercellular communication between these two cells is the quintessential mechanism in bone remodelling. Unfortunately, the importance of this interaction is often neglected and its significance is only realised when disruption of this “cross-talk” results in debilitating bone diseases. Additionally, the number of known proteins that are involved in this “cross-talk”, especially those that are osteoclast-derived, and act specifically on osteoblasts, is limited. This discrepancy leads to the question: Can osteoclasts directly control the growth and function of osteoblastic cells by expressing specific proteins that bind directly to osteoblasts? If so, is it possible to use these proteins to control and, possibly, treat bone disease? The objective of this thesis is to identify and characterise osteoclast-derived factors that can modulate bone homeostasis, as well as contribute to the intercellular communication between osteoblasts and osteoclasts ... Collectively, the data in this thesis culminates in one important conclusion: the identification of a novel paracrine secretory factor that has the potential to directly induce the formation of bone. These findings represent the first ever characterisation of a protein that allows the osteoclasts to directly control the growth and function of osteoblasts. Due to the potential function of ODOF to induce bone formation, this protein may be used therapeutically to treat bone disease.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Akademisk avhandling--Uppsala. / Extra t.p., with thesis statement, inserted. Bibliography: p. 73-76.

Akademisk avhandling--Uppsala. / Extra t.p., with thesis statement, inserted. Bibliography: p. 73-76.

Origin of renal osteodystrophy and cardiovascular complications are multifactorial. This complications are caused by disorders of calcium - phosphate metabolism already at the beginning of patient's irreversible renal failure. The factors playing the most important part in the development o renal ostedystrophy and are hypocalcemia and increasing serum phosphate levels associated with a declining glomerulal filtration. Two main types of renal osteodystrophy can be described - high turnover bone disease and low turnover disease. High turnover forms of renal osteodystrophy are characterized by rapid bone turnover caused by abnormally high PTH levels. The two types of high turnover renal osteodystrophy are predominant hyperparathyroid bone disease, and mixed uremic osteodystrophy. Low turnover forms of renal osteodystrophy are characterized by a dramatic drop in the rate of bone remodeling, caused by oversuppression of PTH and/or by aluminum accumulation. The bones become thin and overly flexible, and bowing may occur. The two types of low turnover renal osteodystrophy are low turnover uremic osteodystrophy and aluminum-related bone disease. Patients who have end-stage renal disease with increased serum phosphate levels and calciumphosphate products are associated with an increased prevalence of ectopic...

Demineralized bone matrix (DBM) is an allograft material used in orthopedics that promotes endochondral bone formation. While the placement of DBM on either the periosteal surface of a bone or within a skeletal muscle promotes the recruitment of stem cells that can form skeletal tissues through the temporal progression of endochondral bone development, it remains unclear to what degree these processes are different between the two sites. In this study, we utilize a comparative in vivo model of endochondral ossification by implanting the DBM on the periosteum and in the muscle. Within the muscle we further compared the effects of DBM with and without Bone morphogenetic protein-2 (BMP-2), a primary morphogenetic factor involved in the differentiation of skeletal stem cells. The mice were harvested at various time points after DBM implantation in order to analyze the development of the bone. Analysis included X-ray imaging, microCT imaging, and mRNA expression. Plain x-ray and micro-CT imaging analysis showed mineralized bone formation in the implant on the periosteum and in the muscle with BMP-2, but no growth in the muscle when BMP-2 was not added to the DBM. The mechanisms for bone development were further analyzed by qRT-PCR to determine temporal patterns and levels of expression of various stem cell and differentiated skeletal cell associated genes. The stem cell gene expression varied between implant placement locations suggesting different mechanisms for stem cell recruitment. Interesting, while DBM implants in the muscle without BMP did not induce mineralized tissue specific mRNA expression; specific stem cell and early skeletal cell lineage commitment genes were present. These results suggest that while DBM in muscle is capable of recruiting stem cells that higher BMP-2 levels are needed to promote the progression of cartilage to mineralized bone in muscle tissues.

Piezocision is a new periodontal method for cutting bone more precisely than conventional methods, such as bur drilling, with 3D ultrasonic vibration power. We have conducted a study on piezocision effect on periodontal tissue in rodents. Our previous animal studies demonstrated that piezocision hastens tooth movement in rodents compared to conventional methods. The histological results showed that piezocision induces bone resorption and regeneration quickly. In addition, we observed the same effect of piezocision surgery on clinical tooth movement in collaboration with the orthodontists at BUSDM. We believe that piezocision can contribute significantly to dental therapies. However, more studies of piezocision effects are necessary for a thorough understanding. Periodontal tissue healing requires the participation of regulatory molecules, cells, and scaffold or matrix. We hypothesized that piezosurgery induces alveolar bone regeneration by uncovered procedures. In this study, we focused on the cells contributing to synthesis or repair of periodontal tissue, such as osteocytes, osteoclasts, osteoblasts, white blood cells, and periodontal ligament cells in order to close the gap between clinical knowledge and cellular mechanisms Histological analysis and MRI data indicates that piezocision surgery enhanced alveolar bone degradation in the post-operative early phase (from day1 to day7), and induced bone regeneration in the post-operative mid phase (from day14 to day28). The structure of alveolar bone was similar to controls in the late phase (day70). Serum ALP activity, a bone formation marker, was significantly increased by Piezocision surgery (p<0.05). Piezocision increasd serum CTX, a bone degradation biomarker, at post-operative 7day in the 30Hz Piezocision surgery (p<0.05). In addition, Serum PINP, a bone formation biomarker, was significantly decreased in the post-operative early phase. TUNEL assays revealed that osteocyte apoptosis was induced in alveolar bone by piezocision at post-operative 1day. Apoptosis in osteocytes induces osteoclast activity that leads to bone degradation. In previous studies piezocision induced TRAP activity in the post-operative early phase. Runx2 positive osteoblast progenitor cells were observed in the post-operative day7 and 14 as assessed by Immunofluorescence microscopy analysis. The Runx2 positive cells accumulated near the new bone formation area. The structure of collagen was observed by histological staining with Pico Sirius Red. Piezocision resulted in deteriorated collagen structure in the post-operative early phase that recovered in the post-operative mid phase. Since the collagen fibers filled in the gap between alveolar bone and roots, we stained the sections with Periostin, a specific PDL biomarker. Periostin was observed on the collagen fibers that filled in the gap between bone and root. previous studies revealed that the expression of Periostin induced TGF beta, a pivotal molecule for osteoblast differentiation. Taken together, these studies indicate that periodontal tissue responds to Piezosurgery by alveolar bone decalcification and regeneration. Further elucidation of the role of the each conducting cells (eg. osteocytes, osteoclast, osteoblast, periodontal ligament cells) after piezosurgery in the periodontal tissue may provide a new target for the treatment of periodontal disease by stimulating the return to tissue homeostasis.

Osteoporosis is an age-related skeletal disease characterised by an increased incidence of fragility fractures. In this thesis I develop a new technique capable of measuring the thickness of the previously unmeasured endocortical region, and providing an improved measure of the cortical bone mineral density (cBMD) from in-vivo clinical CT scans. These features are of interest as both have been linked to fracture risk. \\ The new technique is developed within the cortical bone mapping (CBM) framework so that it provides localised architectural measurements over a bone's surface. Its performance is assessed using simulated QCT data from three simulated phantoms with differing bone architecture, and two paired datasets of ex-vivo QCT and HR-pQCT scans across the proximal femur and the lumbar spine. The simulated data allows for inaccuracies in CBM measurements caused by beam hardening effects to be considered for the first time: I show that beam hardening leads to an underestimation in cortical thickness and an overestimation in trabecular BMD and that these inaccuracies can be reduced through adjustments to the CBM optimisation process. \\ A new technique of analysing HR-pQCT scans is also developed, for the validation of the new CBM method. It was used in place of other established HR-pQCT techniques for its ability to provide localised measurements of the endocortical region. A comparison with the well known full-width half-maximum (FWHM) method shows that it is less susceptible to errors caused by beam hardening. It also measures the mean cBMD, which has a greater clinical relevance than the peak cBMD measured by the FWHM method as it includes the impact of porosity. I demonstrate that the endocortical thickness can be measured to an accuracy of \(-0.15\pm0.71\thinspace\mathrm{mm}\), and that local cBMD measurements are possible down to \(300\thinspace\mathrm{mg/cm}^3\) from QCT scans over the proximal femur. I also validate CBM methods over the vertebrae for the first time and demonstrate that the cortical thickness and endocortical thickness can be measured with accuracies of \(0.10\pm0.30\thinspace\mathrm{mm}\) and \(-0.20\pm0.53\thinspace\mathrm{mm}\). \\ Two clinical trials involving Teriparatide are used to demonstrate that the new CBM method is able to detect significant regional changes in the dense cortical and endocortical bone over the proximal femur and lumbar spine, which can be attributed to changes in intracortical remodelling and endosteal apposition. The analysis of a cross-sectional fracture discrimination trial shows that fracture incidence is associated with significant decreases in endocortical thickness over specific regions.

Introdução: Com o aumento da expectativa de vida dos pacientes com Fibrose Cística (FC), a saúde óssea têm sido objeto de estudo a fim de otimizar a qualidade de vida desses pacientes. A prevalência de massa óssea baixa e os fatores de risco associados são altamente variáveis dependendo da população estudada. Objetivos: Determinar a prevalência de massa óssea baixa em pacientes adolescentes e adultos com FC e estudar os fatores potencialmente associados. Métodos: Densidade mineral óssea foi determinada por DXA na coluna lombar em todos os pacientes e no fêmur em pacientes ≥20 anos. Avaliações nutricionais, bioquímicas e pulmonares foram realizadas. Dados referentes ao tratamento farmacológico foram coletados. Resultados: 58 pacientes foram incluídos no estudo (25 homens/ 33 mulheres), média de idade de 23,9 anos (16-53). Massa óssea baixa foi verificada em 20,7% dos pacientes. Não houve histórico de fratura. Z-score da coluna lombar associou-se positivamente com IMC (r= 0,3; p= 0,022), VEF1% (r=0,415; p=0,001). A média do Z-score da coluna foi mais alta nas mulheres que nos homens (p=0,001), em pacientes que não possuíam insuficiência pancreática (p=0,02) e em pacientes que não haviam sido hospitalizados no período de três meses (p=0,032). Os fatores encontrados como preditores independentes de Z-score da coluna lombar foram sexo masculino e IMC. Conclusão: Massa óssea baixa é frequente em pacientes com FC e está associada ao IMC, o qual provavelmente reflete a severidade da doença, e ao sexo masculino. Esforços devem ser empreendidos com o objetivo de manter esses pacientes com perfil nutricional adequado. / Background: Survival of cystic fibrosis (CF) patients has increased, so bone health could be important for the quality of life of affected patients. Several studies described lower bone mass density (BMD) in patients with CF, which increased fracture risk. Objective: The aim of this study was to evaluate the prevalence of low BMD as well as to evaluate the factors associated with bone mass in these patients. Methods: BMD was measured by DXA in lumpar spine (L1-L4), in patients ≤19years-old, or lumbar spine and femur (total and neck) in patients ≥20years-old. Evaluations of nutritional status, biochemical parameters and lung function were performed. Medications were obtained from medical records Results: Fifty-eight patients were included in the study (25 males/33females), mean age 23.9 years (16-53). The prevalence of bone mass below the expected range for age at any site was 20.7%. None of the subjects had history of fracture. Lumbar spine Z-score in FC patients correlated positively with BMI (r= 0.3, p=0.001), and with FEV1 (%predicted) (r=0.415, p=0.022). Mean lumbar spine Z-score were higher in women (p=0.001), in patients with no pancreatic insufficiency (p=0.032), and in patients with no hospitalization in the last 3 months (p=0.02). BMI (p= 0.001) and sex (p=0.001) were independently associated with the Z-score in the lumbar spine. Conclusion: Low bone mass is a frequent problem in patients with CF, being associated with BMI, which could reflect disease intensity, and male sex. A larger effort should be made to keep these patients well-nourished.

Made available in DSpace on 2014-06-11T19:23:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:50:52Z : No. of bitstreams: 1 coradazzi_lf_me_araca.pdf: 2222457 bytes, checksum: d4df3c1b61fe6c5d468f78b6582caafb (MD5) / Foi realizado um estudo histomorfométrico para avaliar o reparo ósseo em cavidades experimentais criadas na tíbia de coelhos, preenchidas com dois tipos de partículas de osso autógeno. Foram utilizados 12 coelhos, nos quais foram realizadas 3 cavidades unicorticais de 7 mm de diâmetro, com uma broca trefina, na face lateral da tíbia direita. Os defeitos ósseos foram preenchidos respectivamente com partículas de osso autógeno obtidas com um triturador manual, com partículas de osso autógeno recolhidas com um coletor ósseo durante o preparo de cavidades com a seqüência de brocas de implantes e com coagulo sangüíneo servindo como controle. Os animais foram igualmente distribuídos em 3 grupos e sacrificados nos períodos de 7, 15 e 30 dias. De acordo com os resultados obtidos, aos 7 dias todos os grupos apresentaram-se preenchidos por coágulo sangüíneo, sendo observada a presença de partículas ósseas autógenas nos grupos triturado ( 44,75% ) e coletado ( 24% ). No período de 15 dias, notou-se a diferenciação conjuntiva em todos os grupos, com ausência de neoformação óssea no grupo controle ( 0% ), presença de partículas ósseas e início de formação óssea nos grupos coletado (38,88%) e triturado (46%). No período de 30 dias observou-se a neoformação óssea nos grupos controle (50%), coletado (64,63%) e triturado (66%) com a presença de um trabeculado ósseo imaturo. De acordo com a metodologia utilizada, concluiu-se que: a diferença entre a neoformação óssea nas cavidades dos grupos triturado e coletado não foi estatisticamente significante, porem mostrou-se superior a do grupo controle no aspecto quantitativo e qualitativo. As partículas ósseas do grupo triturado não foram totalmente reabsorvidas nos períodos analisados, enquanto que no grupo coletado houve uma reabsorção das partículas ósseas e neoformação óssea superiores aos do grupo triturado. / A histomorphometric study was carried out to evaluate the bone repair in experimental cavities created in rabbits tibiae and filled with two types of particulate autogenous bone grafts. Twelve rabbits were used. In each tibia, on the right lateral face, three 7 mm diameter unicortical cavities were performed with a trephine bur. The bone defects were respectively filled with particles of autogenous bone obtained with manual bone mill, with autogenous bone particles collected with a bone collector during the cavities preparation with implant burs, and with the blood clot serving as a control group. The animals were equally divided in three groups and sacrificed on 7, 15 and 30 days. According to the obtained results, on the seventh day all the groups showed to be filled with blood clots with the presence of autogenous bone particles observed on the triturated group (44,75%) and collected group (24%). At the fifteenth day period it was noted connective tissue differentiation in all the groups, with no bone neoformation noted on the control group (0%). Presence of bone particles and beginning of osteogenesis was noted in the collected (38,88%) and triturated (46%) groups. On the thirtieth day bone neoformation was observed in the control (50%), collected (64,63%) and triturated (66,63%) groups as well as the presence of immature trabecular bone. According to the methodology utilized, it was concluded that the bone formation occurred in the cavities of the triturated and collected groups did not show statistical significance, however being superior to the control group as to the quantitative and qualitative aspect. The bone particles of the triturated group were not totally reabsorbed in the analyzed periods, while in the collected group there was a bone particles resorption and bone neoformation in a higher degree than in the triturated group.