A osteoaderina (OSAD) tem sido identificada nos tecidos mineralizados, porém, seu papel na mineralização óssea não está claro. Foi feita uma comparação do momento em que a OSAD aparece na ossificação intramembranosa e endocondral, em relação aos estágios iniciais de mineralização. O osso parietal de fetos de ratos Wistar com 17, 18 e 21 dias e o côndilo mandibular de ratos com 30 dias foram removidos. A expressão de OSAD foi analisada por imunocitoquímica e Western blotting. Nos dois tipos de ossificação, a imunomarcação foi detectada nos osteoblastos; porém, na matriz extracelular a OSAD apareceu somente na fase fibrilar de mineralização, mantendo-se constante posteriormente. A análise por Western blotting revelou que os fetos com 17 dias continham pouco menos OSAD que os de 18 dias, enquanto a imunorreatividade diminuía nos fetos com 21 dias. Os resultados sugerem que a OSAD tem um papel na mineralização da matriz, atuando, provavelmente como organizadora de seu arcabouço ou retendo o mineral, além de exercer atividades de adesão entre os componentes da matriz. / Osteoadherin (OSAD) had been identified in mineralized tissues, but its specific role in mineralization remains unclear. The present study compared the appearance of OSAD at early stages of mineralization during both intramembranous and endochondral ossification. Parietal bone of 17, 18 and 21 days-old fetus and mandibular condyle of 30 days-old Wistar rats were removed. The expression of OSAD was analyzed by immunocytochemistry and Western blotting. In both types of ossification the labeling was uniformly distributed in the cytoplasm of osteoblasts but it only appeared in the mineralizing matrix when the fibrilar stage was taking place, remaining as a component of the mineralized bone matrix. Western blots revealed that 17-days-old embryos contained slightly less OSAD than 18- days-old fetus, while immunoreactivity was weak in 21 days-old fetus. The results suggest that OSAD plays a role in collagen fibril mineralization maybe by organizing the matrix assembly or by retaining the mineral into the matrix, besides exerting binding activities among its components.

Die Struktur des Knochenmaterials wird während des gesamten Lebens durch dynamische Prozessen verändert. Diese sind der Umbauprozess, bei dem existierendes Material entfernt und durch neues, vorerst weiches ersetzt wird. In dieses weiche Material wird im sog. Mineralisierungsprozess Mineral eingelagert und somit die Steifigkeit erhöht. Diese zwei Prozesse führen zu einem heterogenen Knochenmaterial. Das komplexe Zusammenspiel kann durch Knochenkrankheiten beeinflusst werden und zu einem mechanischen Versagen des Materials führen. Wie viel Einfluss dabei allein dem Umbauprozess und dem Mineralisierungsprozess zuzuschreiben sind, konnte bislang nicht geklärt werden. An diese Fragestellungen wird in der vorliegenden Dissertation mit physikalischen und numerischen Methoden herangegangen. Das heterogene Material ist das Ergebnis des Mineralisierungs- und Umbauprozesses und wird abkürzend BMDD (für bone mineralization density distribution) genannt, die für alle gesunden Menschen gleich ist und bei Knochenkrankheiten davon abweicht. Mittels Modellierung wird eine Störung in der Mineralisierung simuliert, die zu Verschiebungen in der BMDD führt. Diese Verschiebungen können verglichen werden mit einem veränderten Umbauprozess. Der unterschiedliche Einfluss der beiden Prozesse liegt im zeitlichen Verlauf. Die Mineralisierungskinetik im Knochen konnte durch die neuartige Auswertung von 3D in vivo micro-CT-Bildern von Mäusen erstmals quantifiziert werden. Die Auswertung bestätigte, die schnellere Mineralisierung im neugeformten und die langsamere in bereits vorhandenem Knochen. Wie der Umbauprozess im kompakten Knochen gesteuert sein kann, wurde mittels Anordnungsmechanismen der Osteone beschrieben. Für einen solchen Knochenbaustein war es verboten innerhalb einer definierten Zone eines anderen Bausteins gebildet zu werden. Diese Zone ließ sich am besten durch einen normalverteilten Radius, mit einer dazugehörigen Variabilität beschreiben. / The structure of the bone material is continuously changed during the life by dynamic processes. These are the remodeling process during which the existing material is replaced by new, initially soft material. In this soft material mineral is incorporated during the so called mineralization process, thus increasing the stiffness. These two processes lead to a heterogeneous bone material. Their interplay can be perturbed by bone diseases, which can lead to material failure. It remains unclear to which degree each of these two processes contributes during diseases. Yet, while the remodeling process is known to be mechanically controlled, it is unclear how mechanical stimuli affect the mineralization process. The heterogeneous mineral distribution in trabecular bone is the result of the complex interplay between the mineralization and the remodeling process and is called bone mineralization density distribution (BMDD). The BMDD is similar for all healthy adult humans. A deviation from this healthy distribution is indicative of bone diseases. With a mathematical model the influence of changed mineralization kinetics on the BMDD is investigated and compared to a remodeling change. The different influences lie in the time development. With a novel 3D analysis of in vivo micro-CT of the vertebra in a mouse tail the mineralization kinetics could be quantified for the first time. It could be e.g. shown that the bone is demineralized before it is completely resorbed. An algorithm was developed to understand how the remodeling process can be regulated. The arrangement of the building blocks could be described when such a block could only be placed within a defined zone of another building block. This zone could be best quantified when its radius was normally distributed with a corresponding standard deviation.

A osteoaderina (OSAD) tem sido identificada nos tecidos mineralizados, porém, seu papel na mineralização óssea não está claro. Foi feita uma comparação do momento em que a OSAD aparece na ossificação intramembranosa e endocondral, em relação aos estágios iniciais de mineralização. O osso parietal de fetos de ratos Wistar com 17, 18 e 21 dias e o côndilo mandibular de ratos com 30 dias foram removidos. A expressão de OSAD foi analisada por imunocitoquímica e Western blotting. Nos dois tipos de ossificação, a imunomarcação foi detectada nos osteoblastos; porém, na matriz extracelular a OSAD apareceu somente na fase fibrilar de mineralização, mantendo-se constante posteriormente. A análise por Western blotting revelou que os fetos com 17 dias continham pouco menos OSAD que os de 18 dias, enquanto a imunorreatividade diminuía nos fetos com 21 dias. Os resultados sugerem que a OSAD tem um papel na mineralização da matriz, atuando, provavelmente como organizadora de seu arcabouço ou retendo o mineral, além de exercer atividades de adesão entre os componentes da matriz. / Osteoadherin (OSAD) had been identified in mineralized tissues, but its specific role in mineralization remains unclear. The present study compared the appearance of OSAD at early stages of mineralization during both intramembranous and endochondral ossification. Parietal bone of 17, 18 and 21 days-old fetus and mandibular condyle of 30 days-old Wistar rats were removed. The expression of OSAD was analyzed by immunocytochemistry and Western blotting. In both types of ossification the labeling was uniformly distributed in the cytoplasm of osteoblasts but it only appeared in the mineralizing matrix when the fibrilar stage was taking place, remaining as a component of the mineralized bone matrix. Western blots revealed that 17-days-old embryos contained slightly less OSAD than 18- days-old fetus, while immunoreactivity was weak in 21 days-old fetus. The results suggest that OSAD plays a role in collagen fibril mineralization maybe by organizing the matrix assembly or by retaining the mineral into the matrix, besides exerting binding activities among its components.

Osteoporosis is a systemic bone disease with an increasing prevalence in the elderly population. There is conflicting opinion about whether osteoporosis affects the alveolar bone of the jaws and whether it poses a risk to the osseointegration of dental implants. The aim of the present study was to evaluate the effects of systemic glucocorticoid administration on the jaw bone density of minipigs. Thirty-seven adult female minipigs were randomly divided into two groups. Quantitative computed tomography (QCT) was used to assess bone mineral density BMD of the lumbar spine as well as the mandible and maxilla, and blood was drawn. One group of minipigs initially received 1.0 mg prednisolone per kg body weight daily for 2 months. The dose was tapered to 0.5 mg per kg body weight per day thereafter. The animals in the other group served as controls and received placebo. QCT and blood analysis were repeated after 6 and 9 months. BMD was compared between the two groups by measuring Hounsfield units, and serum levels of several bone metabolic markers were also assessed. A decrease in BMD was observed in the jaws from baseline to 9 months. This was more pronounced in the prednisolone group. Statistically significant differences were reached for the mandible (p < 0.001) and the maxilla (p < 0.001). The administration of glucocorticoids reduced the BMD in the jaws of minipigs. The described model shows promise in the evaluation of osseointegration of dental implants in bone that is compromised by osteoporosis.

Hyperthyroidism causes secondary osteoporosis through favoring bone resorption over bone formation, leading to bone loss with elevated bone fragility. Osteocytes that reside within lacunae inside the mineralized bone matrix orchestrate the process of bone remodeling and can themselves actively resorb bone upon certain stimuli. Nevertheless, the interaction between thyroid hormones and osteocytes and the impact of hyperthyroidism on osteocyte cell function are still unknown. In a preliminary study, we analyzed bones from male C57BL/6 mice with drug-induced hyperthyroidism, which led to mild osteocytic osteolysis with 1.14-fold larger osteocyte lacunae and by 108.33% higher tartrate-resistant acid phosphatase (TRAP) activity in osteocytes of hyperthyroid mice compared to euthyroid mice. To test whether hyperthyroidism-induced bone changes are reversible, we rendered male mice hyperthyroid by adding levothyroxine into their drinking water for 4 weeks, followed by a weaning period of 4 weeks with access to normal drinking water. Hyperthyroid mice displayed cortical and trabecular bone loss due to high bone turnover, which recovered with weaning. Although canalicular number and osteocyte lacunar area were similar in euthyroid, hyperthyroid and weaned mice, the number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick end labeling (TUNEL)-positive osteocytes was 100% lower in the weaning group compared to euthyroid mice and the osteocytic TRAP activity was eightfold higher in hyperthyroid animals. The latter, along with a 3.75% lower average mineralization around the osteocyte lacunae in trabecular bone, suggests osteocytic osteolysis activity that, however, did not result in significantly enlarged osteocyte lacunae. In conclusion, we show a recovery of bone microarchitecture and turnover after reversal of hyperthyroidism to a euthyroid state. In contrast, osteocytic osteolysis was initiated in hyperthyroidism, but its effects were not reversed after 4 weeks of weaning. Due to the vast number of osteocytes in bone, we speculate that even minor individual cell functions might contribute to altered bone quality and mineral homeostasis in the setting of hyperthyroidism-induced bone disease. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Osteoporosis is a systemic bone disease with an increasing prevalence in the elderly population. There is conflicting opinion about whether osteoporosis affects the alveolar bone of the jaws and whether it poses a risk to the osseointegration of dental implants. The aim of the present study was to evaluate the effects of systemic glucocorticoid administration on the jaw bone density of minipigs. Thirty-seven adult female minipigs were randomly divided into two groups. Quantitative computed tomography (QCT) was used to assess bone mineral density BMD of the lumbar spine as well as the mandible and maxilla, and blood was drawn. One group of minipigs initially received 1.0 mg prednisolone per kg body weight daily for 2 months. The dose was tapered to 0.5 mg per kg body weight per day thereafter. The animals in the other group served as controls and received placebo. QCT and blood analysis were repeated after 6 and 9 months. BMD was compared between the two groups by measuring Hounsfield units, and serum levels of several bone metabolic markers were also assessed. A decrease in BMD was observed in the jaws from baseline to 9 months. This was more pronounced in the prednisolone group. Statistically significant differences were reached for the mandible (p < 0.001) and the maxilla (p < 0.001). The administration of glucocorticoids reduced the BMD in the jaws of minipigs. The described model shows promise in the evaluation of osseointegration of dental implants in bone that is compromised by osteoporosis.

Objetivos: Avaliar a estatura final, mineralização e marcadores de mineralização óssea de adultos com síndrome nefrótica (SN) idiopática corticossensível na infância e adolescência e analisar a influência da doença, suas comorbidades e do alvo de estatura no crescimento e mineralização destes pacientes. Casuística: Avaliamos a estatura final de 60 pacientes (41 masculinos e 19 femininos) com idade mínima de dezenove anos ou desenvolvimento genital P4G4 nos masculinos e menarca nos femininos portadores de SN corticossensível na infância e adolescência. Realizamos a densitometria óssea (DMO=g/cm2) em 26 destes pacientes e em 35 controles, com análise concomitante dos níveis séricos de 25 OH vitamina D3 (25(OH)D), Paratormônio (PTH), telopéptido carboxiterminal do colágeno tipo 1( (CTx), Propeptídeo Aminoterminal do Colágeno Tipo I (P1NP) e Osteocalcina (OC) Resultados: A idade média inicial dos 60 pacientes foi de 5a3m e final de 20a5m, com acompanhamento médio de 15a2m. A dose média de prednisona utilizada foi de 1264 mg/kg. O Zscore médio da estatura inicial (-0,60; SD: 1,0) e final (0,64; SD: 0,92), não diferiu significativamente (Teste T: p=0,72) entre si. O Zscore estatura na idade adulta se correlacionou significativamente apenas com o Zscore estatura inicial e com o Zscore alvo de estatura. Seis pacientes atingiram Zscore estatura < -2 na idade adulta e este achado demonstrou forte correlação com o Zscore estatura inicial e com o Zscore alvo de estatura. A DMO e Zscore DMO de L1L4, Cabeça do fêmur e do Fêmur total dos pacientes e controles não diferiram significativamente. 6 pacientes e 2 controles apresentaram Zscore DMO < -2 (massa óssea reduzida) enquanto 2 pacientes e 1 controle demonstraram , Zscore DMO < -2,5 (osteoporose). Pacientes com massa óssea reduzida receberam 2189 mg/kg de prednisona durante 13 anos e aqueles com osteoporose, 2510 mg/kg durante 14 anos. Estes valores, comparados com aqueles de pacientes com massa óssea normal, mostraram significância estatística (p=0,01). Não houve correlação significativa entre as demais variáveis analisadas e a DMO. Os marcadores 25(OH)D, PTH, CTx, P1NP e OC dos pacientes e controles não diferiram significativamente. Quando analisados em relação à doença e suas comorbidades, DMO e estatura final não apresentaram significação estatística. Conclusões: 1. Os valores de Zscore estatura inicial e final se correlacionaram fortemente com o alvo de estatura. 2. Não houve associação entre as características clinicas da doença e a aquisição do alvo de estatura, neste grupo de pacientes. 3. A massa óssea e os marcadores de mineralização dos pacientes não diferiram quando comparados aos controles. 4. Os 6 pacientes com massa óssea reduzida (2 com osteoporose) utilizaram dose total e tempo de uso da prednisona significativamente maior que aqueles com massa óssea adequada 5. Não houve correlação entre os níveis séricos dos marcadores de mineralização óssea e a doença e suas comorbidades, a estatura final e a DMO dos pacientes adultos com SN na infância e adolescência / Objectives: The aim of the present study was to evaluate the final height, bone mineral density (BMD) and bone mineralization markers of adults with steroid responsive Idiopathic Nephrotic Syndrome (NS) in childhood and adolescence and to examine the influence of the disease, its co-morbidities and the patients\' target height in the final height and mineralization results. Patients and Methods: We have analyzed initial and final anthropometric data of 60 patients (41 male and 19 females) and / or their records, with a minimum age of nineteen years or fully developed pubertal status (P4G4 in males and menarche in females). BMD (g/cm2) was evaluated in 26 patients and in 35 controls, with a concomitant analysis, of serum levels of 25-OH Vitamin D (25(OH)D), Parathyroid Hormone (PTH); C-terminal telopeptide of type I collagen (CTx) and aminoterminal propeptide of type 1 procollagen (P1NP) and Osteocalcin (OC) Results: Mean age at first consultation was 5.3 years (SD: 2.4 yrs) and at last consultation was 20.4 yrs (SD: 3.0 yrs). The mean cumulative dose of prednisone was 1254 mg/kg (SD: 831.39 mg/kg). The mean initial height SDS was -0.60; (SD: 1.0) the final height SDS was -0.64; (SD: 0.92), (t-test: p=0.72). The final height SDS showed correlated significantly only with the initial height SDS and the target height SDS. Six patients achieved a final height SDS <-2 and this finding showed a strong correlation to the initial height SDS and to the target height SDS in the male patients. The patients\' and control subjects L1L4 head of the femur and the total femur BMD and BMD SDS did not differ significantly. 6 patients and 2 control subjects showed a BMD SDS <-2 (low bone mass) while 2 patients and 1 control subjects showed a BMD SDS <-2.5 (osteoporosis). Patients with BMD SDS <-2 received 2189 mg / kg of prednisone over 13 years while those with a BMD SDS <-2.5 received 2510 mg / kg prednisone for 14 years (p = 0.01 vs BMD SDS -2 ). No other studied variable correlated significantly with BMD. The studied bone biomarkers showed similar results in patients and control subjects without a significant correlation with disease activity, co-morbidities, and BMD or height parameters. Conclusion: 1. the initial and final height SDS were strongly correlated to the height target. 2. INS and its co-morbidities did not prevent the patients to reach their target height 3. The patients\' BMD and bone mineralization markers did not differ when compared to controls. 4. The 6 patients with low bone mass (2 with osteoporosis) used a total dose of prednisone for a longer period of time in relation to those with an adequate BMD 5. There was no correlation between bone mineralization markers, disease activity and its co-morbidities, final height and BMD of adult patients with INS in childhood and adolescence

Objetivos: Avaliar a estatura final, mineralização e marcadores de mineralização óssea de adultos com síndrome nefrótica (SN) idiopática corticossensível na infância e adolescência e analisar a influência da doença, suas comorbidades e do alvo de estatura no crescimento e mineralização destes pacientes. Casuística: Avaliamos a estatura final de 60 pacientes (41 masculinos e 19 femininos) com idade mínima de dezenove anos ou desenvolvimento genital P4G4 nos masculinos e menarca nos femininos portadores de SN corticossensível na infância e adolescência. Realizamos a densitometria óssea (DMO=g/cm2) em 26 destes pacientes e em 35 controles, com análise concomitante dos níveis séricos de 25 OH vitamina D3 (25(OH)D), Paratormônio (PTH), telopéptido carboxiterminal do colágeno tipo 1( (CTx), Propeptídeo Aminoterminal do Colágeno Tipo I (P1NP) e Osteocalcina (OC) Resultados: A idade média inicial dos 60 pacientes foi de 5a3m e final de 20a5m, com acompanhamento médio de 15a2m. A dose média de prednisona utilizada foi de 1264 mg/kg. O Zscore médio da estatura inicial (-0,60; SD: 1,0) e final (0,64; SD: 0,92), não diferiu significativamente (Teste T: p=0,72) entre si. O Zscore estatura na idade adulta se correlacionou significativamente apenas com o Zscore estatura inicial e com o Zscore alvo de estatura. Seis pacientes atingiram Zscore estatura < -2 na idade adulta e este achado demonstrou forte correlação com o Zscore estatura inicial e com o Zscore alvo de estatura. A DMO e Zscore DMO de L1L4, Cabeça do fêmur e do Fêmur total dos pacientes e controles não diferiram significativamente. 6 pacientes e 2 controles apresentaram Zscore DMO < -2 (massa óssea reduzida) enquanto 2 pacientes e 1 controle demonstraram , Zscore DMO < -2,5 (osteoporose). Pacientes com massa óssea reduzida receberam 2189 mg/kg de prednisona durante 13 anos e aqueles com osteoporose, 2510 mg/kg durante 14 anos. Estes valores, comparados com aqueles de pacientes com massa óssea normal, mostraram significância estatística (p=0,01). Não houve correlação significativa entre as demais variáveis analisadas e a DMO. Os marcadores 25(OH)D, PTH, CTx, P1NP e OC dos pacientes e controles não diferiram significativamente. Quando analisados em relação à doença e suas comorbidades, DMO e estatura final não apresentaram significação estatística. Conclusões: 1. Os valores de Zscore estatura inicial e final se correlacionaram fortemente com o alvo de estatura. 2. Não houve associação entre as características clinicas da doença e a aquisição do alvo de estatura, neste grupo de pacientes. 3. A massa óssea e os marcadores de mineralização dos pacientes não diferiram quando comparados aos controles. 4. Os 6 pacientes com massa óssea reduzida (2 com osteoporose) utilizaram dose total e tempo de uso da prednisona significativamente maior que aqueles com massa óssea adequada 5. Não houve correlação entre os níveis séricos dos marcadores de mineralização óssea e a doença e suas comorbidades, a estatura final e a DMO dos pacientes adultos com SN na infância e adolescência / Objectives: The aim of the present study was to evaluate the final height, bone mineral density (BMD) and bone mineralization markers of adults with steroid responsive Idiopathic Nephrotic Syndrome (NS) in childhood and adolescence and to examine the influence of the disease, its co-morbidities and the patients\' target height in the final height and mineralization results. Patients and Methods: We have analyzed initial and final anthropometric data of 60 patients (41 male and 19 females) and / or their records, with a minimum age of nineteen years or fully developed pubertal status (P4G4 in males and menarche in females). BMD (g/cm2) was evaluated in 26 patients and in 35 controls, with a concomitant analysis, of serum levels of 25-OH Vitamin D (25(OH)D), Parathyroid Hormone (PTH); C-terminal telopeptide of type I collagen (CTx) and aminoterminal propeptide of type 1 procollagen (P1NP) and Osteocalcin (OC) Results: Mean age at first consultation was 5.3 years (SD: 2.4 yrs) and at last consultation was 20.4 yrs (SD: 3.0 yrs). The mean cumulative dose of prednisone was 1254 mg/kg (SD: 831.39 mg/kg). The mean initial height SDS was -0.60; (SD: 1.0) the final height SDS was -0.64; (SD: 0.92), (t-test: p=0.72). The final height SDS showed correlated significantly only with the initial height SDS and the target height SDS. Six patients achieved a final height SDS <-2 and this finding showed a strong correlation to the initial height SDS and to the target height SDS in the male patients. The patients\' and control subjects L1L4 head of the femur and the total femur BMD and BMD SDS did not differ significantly. 6 patients and 2 control subjects showed a BMD SDS <-2 (low bone mass) while 2 patients and 1 control subjects showed a BMD SDS <-2.5 (osteoporosis). Patients with BMD SDS <-2 received 2189 mg / kg of prednisone over 13 years while those with a BMD SDS <-2.5 received 2510 mg / kg prednisone for 14 years (p = 0.01 vs BMD SDS -2 ). No other studied variable correlated significantly with BMD. The studied bone biomarkers showed similar results in patients and control subjects without a significant correlation with disease activity, co-morbidities, and BMD or height parameters. Conclusion: 1. the initial and final height SDS were strongly correlated to the height target. 2. INS and its co-morbidities did not prevent the patients to reach their target height 3. The patients\' BMD and bone mineralization markers did not differ when compared to controls. 4. The 6 patients with low bone mass (2 with osteoporosis) used a total dose of prednisone for a longer period of time in relation to those with an adequate BMD 5. There was no correlation between bone mineralization markers, disease activity and its co-morbidities, final height and BMD of adult patients with INS in childhood and adolescence