Bone is refractory to most conventional biochemical Procedures. However because it is now possible to cut sections (e. g. lopm) of fresh, undemineralized adult bone, this tissue can be analyzed by suitably modified methods of quantitative cytochemistry. A new substrate for assaying hydroxyacyl dehydrogenase activity demonstrated that bone cells may use fatty acids as a major source of energy: detailed analysis of the activities of key enzymes indicated that the paradox of ‘aerobic glycolysis’ of bone could be explained by fatty acid oxidation satisfying the requirements of the Krebs' cycle and directing the conversion of pyruvate to lactate The influence of glucose 6-phosphate dehydrogenase (G6PD) activity in aerobic glycolysis has been considered. The inverse relationships between this activity and that of Na-K-ATPase led to the development of a new method for the latter, based on a new concept in cytochemistry ('hidden-capture' procedure). A major feature of fracture-healing is increased periosteal G6PD activity. The association with the vitamin K cycle has been investigated by feeding rats with dicoumarol which not only inhibited bone-formation but also G6PD activity. The stimulation of this activity in fracture-healing has been linked with ornithine decarboxylase (ODC) activity, for which a new method has been developed. Rats deficient in pyridoxal phosphate (cofactor for ODC) had decreased G6PD responses and also appeared to become osteoporotic. Studies on osteoporotic fractures in the human showed the presence of relatively large apatite crystals close to the fracture-site, and disorganized glycosaminoglycans (demonstrated by the new method of ‘induced birefringence’).

Todo indivíduo nasce com um potencial genético de crescimento, que poderá ou não ser atingido, dependendo das condições de vida a que esteja submetido. Pode-se dizer que o crescimento sofre influência de fatores intrínsecos (genéticos e metabólicos) e extrínsecos (fatores ambientais como a alimentação, a saúde, a higiene, a habitação e o acesso aos serviços de saúde). Entre fatores nutricionais destacam-se as deficiências de vitaminas e oligoelementos que podem associar-se à desnutrição ou depender da absorção insuficiente dos mesmos. Sendo o cálcio um dos principais componentes do tecido mineral ósseo, podemos sugerir que este seja o principal nutriente para a adequada formação óssea e, considerando que a vitamina D desempenha papel importante no metabolismo do cálcio, uma dieta insuficiente nestes nutrientes pode influenciar a formação do esqueleto. Esta revisão da literatura visa enfatizar a importância nutricional do cálcio e vitamina D no processo de crescimento e desenvolvimento, auxiliando profissionais da área da saúde na atualização quanto às recomendações e fontes dietéticas de ambos nutrientes. Assim, em crianças e adolescentes, a baixa ingestão ou baixa absorção de cálcio e vitamina D pode limitar seu desenvolvimento estatural, sendo necessário fornecer quantidades suficientes de ambos na fase critica do crescimento. / Every individual is born with a genetic potential for growth, which may or not be attained, depending on their living conditions. It could be said that growth is influenced by intrinsic (genetic and metabolic) and extrinsic factors (environmental factors such as diet, health, hygiene, housing and access to health services). Outstanding among the nutritional factors are vitamin and oligoelement deficiencies which may be associated with malnutrition or depend on insufficient absorption. Since calcium is the one of main mineral bone tissue component, we suggest that this is the main nutrient for adequate bone formation and, considering that vitamin D plays an important role in calcium metabolism, a diet with an insufficient amount of these nutrients can influence the formation of the skeleton. This review of the literature aims to emphasize the nutritional importance of calcium and vitamin D in the growth and development process, helping health care professionals update the recommendations and dietary sources of both nutrients. Thus, in children and adolescents, the low intake or low absorption of calcium and vitamin D may limit their stature development, and it will be necessary to supply sufficient amounts of both during the critical growth phase.

Todo indivíduo nasce com um potencial genético de crescimento, que poderá ou não ser atingido, dependendo das condições de vida a que esteja submetido. Pode-se dizer que o crescimento sofre influência de fatores intrínsecos (genéticos e metabólicos) e extrínsecos (fatores ambientais como a alimentação, a saúde, a higiene, a habitação e o acesso aos serviços de saúde). Entre fatores nutricionais destacam-se as deficiências de vitaminas e oligoelementos que podem associar-se à desnutrição ou depender da absorção insuficiente dos mesmos. Sendo o cálcio um dos principais componentes do tecido mineral ósseo, podemos sugerir que este seja o principal nutriente para a adequada formação óssea e, considerando que a vitamina D desempenha papel importante no metabolismo do cálcio, uma dieta insuficiente nestes nutrientes pode influenciar a formação do esqueleto. Esta revisão da literatura visa enfatizar a importância nutricional do cálcio e vitamina D no processo de crescimento e desenvolvimento, auxiliando profissionais da área da saúde na atualização quanto às recomendações e fontes dietéticas de ambos nutrientes. Assim, em crianças e adolescentes, a baixa ingestão ou baixa absorção de cálcio e vitamina D pode limitar seu desenvolvimento estatural, sendo necessário fornecer quantidades suficientes de ambos na fase critica do crescimento. / Every individual is born with a genetic potential for growth, which may or not be attained, depending on their living conditions. It could be said that growth is influenced by intrinsic (genetic and metabolic) and extrinsic factors (environmental factors such as diet, health, hygiene, housing and access to health services). Outstanding among the nutritional factors are vitamin and oligoelement deficiencies which may be associated with malnutrition or depend on insufficient absorption. Since calcium is the one of main mineral bone tissue component, we suggest that this is the main nutrient for adequate bone formation and, considering that vitamin D plays an important role in calcium metabolism, a diet with an insufficient amount of these nutrients can influence the formation of the skeleton. This review of the literature aims to emphasize the nutritional importance of calcium and vitamin D in the growth and development process, helping health care professionals update the recommendations and dietary sources of both nutrients. Thus, in children and adolescents, the low intake or low absorption of calcium and vitamin D may limit their stature development, and it will be necessary to supply sufficient amounts of both during the critical growth phase.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-14T16:47:07Z No. of bitstreams: 1 PGCA16MA205.pdf: 2376420 bytes, checksum: 7adb5710821c906867f36fd27eb356b4 (MD5) / Made available in DSpace on 2018-03-14T16:47:07Z (GMT). No. of bitstreams: 1 PGCA16MA205.pdf: 2376420 bytes, checksum: 7adb5710821c906867f36fd27eb356b4 (MD5) Previous issue date: 2016-07-06 / PROMOP / CAPES / This study aimed to analyze and compare different combinations of biocements in relation to osteoinductive and osseocondutive potential, applied by growth guides in rabbit calvaria. We used 14 New Zealand male rabbits, with 6 months of age and average weight of 3.28 ± 0.44 kg, proved healthy through physical examination and hematologic analysis. After performing anesthesia, the animals underwent periosteal bone exposure of the calvaria and each rabbit were attached four cylindrical polyamide guides with stainless steel bolt. Of these guides, three were filled with materials in the form of biocement consisting of: hydroxyapatite 100% (HA 100%), Hydroxyapatite 95% plus Alumina 5% (HA95% + Al5%) and Hydroxyapatite 99% plus Mg 1% (HA99% + Mg1%) and one with autologous blood clot (control). The animals were randomly assigned into two groups: M60 (n = 07) and M90 (n = 07) who were euthanized at 60 and 90 days postoperativelyand the calvaria was removed and wrapped in formaldehyde for 15 days. After, the calvaria was sectioned in four squares, each containing the biomaterial or control and is maintained in buffered formaldehyde for 15 days for histological evaluations and scanning electron microscopy (SEM). Analyzing the images and histological micrographs obtained with the SEM the control samples showed no significant bone growth. The biocements formed by HA100% and HA99% + Mg1% proved promising, leading to an important exoskeletal bone growth (osteoinduction), since the base and the apex of the samples (osseoconduction) and showed no rejection indicated by small amount of fibrous tissue and inflammatory cells. Samples containing HA99% + Mg1% provided greater bone growth at an early stage as compared those containing HA100%. Samples composed of hydroxyapatite 95% + Alumina 5% did not obtain satisfactory results, leading to tiny bone formation and showing signs of rejection. Based on these, the biociment composed of HA100% and the composite formed by HA99% and Mg1% are promising and likely to be used as bone neocresciment promoters / O presente estudo objetivou analisar e comparar diferentes combinações de biocimentos em relação ao seu potencial osseoindutivo e osseocondutivo, quando plicados através de guias de crescimento na calvária de coelhos. Foram utilizados 14 coelhos da raça Nova Zelândia, machos, com 6 meses de idade e peso médio de 3,28 ± 0,44 kg, comprovadamente hígidos através de exame físico e análise hematológica. Após realização de anestesia e em adequado plano cirúrgico, os animais foram submetidos à exposição óssea periosteal da região da calvária, onde, em cada coelho, foram fixados com parafuso de aço inoxidável, quatro guias cilíndricas de poliamida. Destas guias, três foram preenchidas com materiais na forma de biocimento, compostos por: Hidroxiapatita a 100% (HA 100%), Hidroxiapatita 95% + Alumina 5% (HA95% + Al5%) e Hidroxiapatita 99% + Magnésio 1% (HA99% + Mg1%) e uma com coágulo sanguíneo autólogo (controle). Os animais foram distribuídos aleatoriamente em dois grupos: M60 (n=07) e M90 (n=07), que foram eutanasiados com 60 e 90 dias de pós-operatório, respectivamente, sendo a calvária removida e acondicionada em formaldeído por 15 dias. Após, a calvária foi seccionada na forma de quatro quadrados, cada qual contendo o biomaterial ou o controle, sendo mantidos em formaldeído tamponado por mais 15 dias e então encaminhados para avaliações histológicas e para a realização de microscopia eletrônica por varredura (MEV). Analisando as imagens histológicas e as micrografias obtidas com a MEV, observou-se que as amostras controle não apresentaram crescimento ósseo expressivo. Os biocimentos formados por HA100% e HA99% + Mg1% se mostraram bastante promissores, levando a um importante crescimento ósseo exoesqueletal (osseoindução), desde a base quanto ao ápice das amostras (osseocondução) e apresentaram ausência de rejeição, indicada pela pequena quantidade de tecido fibroso e células inflamatórias. As amostras contendo HA99% + Mg1% proporcionaram maior crescimento ósseo em uma fase inicial quanto comparada as que continham HA100%. As amostras compostas por hidroxiapatita 95% + Alumina 5% não obtiveram resultados satisfatórios, levando à ínfima neoformação óssea e apresentando sinais de rejeição. Frente ao exposto, o biocimento composto por HA 100% e o compósito formado por HA99% e Mg1% são promissores e passíveis de serem utilizados como promotores de neocrescimento ósseo

O alcoolismo é considerado um redutor da formação óssea, podendo levar a distúrbios osteometabólicos, já a rhBMP-2 é uma proteína morfogenética conhecida por desempenhar um papel importante nos processos de reparação e indução da formação óssea. O objetivo deste estudo foi investigar a ação do alcoolismo e a resposta do reparo em defeitos ósseos (DO) na calvária de ratos, após a aplicação da rhBMP-2, pura e combinada a uma matriz de colágeno. Foram utilizados 80 ratos divididos em 8 grupos, cada um deles com um período de espera até o sacrifício de 4 e 6 semanas, após a criação cirúrgica do defeito ósseo na calvária de 5 mm. Os grupos foram divididos em G1) água \"ad libitum\" + DO, G2) álcool \"ad libitum\" + DO, G3) água + DO + 5&mu;g rhBMP-2 pura, G4) álcool + DO + 5&mu;g rhBMP-2 pura, G5) água + DO + carreador esponja de colágeno, G6) álcool + DO + carreador esponja de colágeno, G7) água e + DO + 5&mu;g rhBMP- 2/esponja de colágeno, G8) álcool + DO + 5&mu;g rhBMP-2/esponja de colágeno. Os dados radiográficos e os dados para a análise de fibras colágena tipo I e III foram submetidos à análise estatística Kruskal-Wallis e Dunn\'s Multiple, os dados histológicos ao teste de análise de variância (ANOVA) e Tukey. O resultado encontrado para a análise radiográfica no tempo de 6 semanas demonstrou que os grupos tratados com rhBMP-2 independente da utilização do carreador e do etanol apresentaram maior neoformação óssea (p<0,05), para o tempo de 4 semanas não foi encontrada diferença estatística. Para a análise imunoistoquímica, a ostecalcina (OC) e sialoproteína óssea (BPS) foram predominantes nos grupos tratados com rhBMP-2. Para a análise histológica, a quantificação de fibras colágenas tipo I apresentou diferença estatística entre os grupos (p<0,05), com aumento destas fibras principalmente nos grupos tradados com rhBMP-2 associado a esponja de colágeno; e na análise quantitativa por estereologia, o volume de tecido ósseo neoformado foi maior para os grupos tratados com rhBMP-2 pura ou associada ao carreador, porém para os grupos tratados com etanol, houve maior neoformação óssea para o grupo tratado com rhBMP-2 associado ao carreador nos períodos de 4 e 6 semanas (p<0,001). Concluiu-se neste modelo experimental que, o carreador foi efetivo na bioliberação da rhBMP-2, mesmo na presença do etanol. / Alcoholism is considered a reducer for new bone formation, may leading to osteometabolic disturbance, considering that the rhBMP-2 is a morphogenetic protein known to play an important role in the bone healing processes. The aim of this study was to investigate the action of alcoholism and its effect on the repair of bone defects (DO) performed in rat calvaria after the rhBMP-2 application, pure or combined with a collagen matrix. We used 80 rats divided into eight groups, each one with a waiting period for sacrifice of 4 and 6 weeks after the bone defect (5mm) delineation in the rat skull. The groups were divided into: G1) water \"ad libitum\" + DO, G2) alcohol \"ad libitum\" + DO, G3) water + DO + 5&mu;g pure rhBMP-2, G4) alcohol + DO + 5&mu;g pure rhBMP-2, G5 ) DO + water + collagen sponge carrier, G6) alcohol + DO + collagen sponge carrier, G7) and water + DO + 5&mu;g rhBMP-2/collagen sponge, G8) alcohol + DO + 5&mu;g of rhBMP-2/collagen sponge. The radiographic data were submitted to statistical analysis Kruskal-Wallis and Dunn\'s Multiple, histological data to analysis of variance (ANOVA) and Tukey test. Radiographically, it was found after 6 weeks that the groups treated with rhBMP-2, independently of the carrier use and ethanol administration, more new bone formation (p<0.05), at 4 weeks it was not found statistical difference. For immunohistochemical analysis, ostecalcin (OC), and bone sialoprotein (BPS) were predominant in groups treated with rhBMP-2. For histological quantification of collagen type I fibers, statistical difference between groups was found (p<0.05) with the increasing of these fibers in the groups treated with rhBMP-2 combined with collagen sponge; and quantitative by stereology, aiming to calculate the volume of new bone, it was found higher values for the groups treated with rhBMP-2 pure or combined to the carrier; but for the groups treated with ethanol, it was found higher bone formation in the groups treated with rhBMP-2 associated to the carrier in the periods of 4 and 6 weeks (p <0.001). It was concluded in this experimental model that the carrier was effective for rhBMP-2 delivery, even in the presence of ethanol.

O objetivo do presente estudo foi comparar a eficácia da implantação de biomateriais porosos na neoformação óssea e reparo de defeitos cervicais mandibulares em cães, com ou sem a técnica de regeneração óssea guiada (ROG). Bio-Oss Block® (BB), Bio-Oss Collagen® (BC), Bio-Oss® em grânulos (BG), osso autógeno (Ab) e coágulo (Cg) foram utilizados nas mesmas situações experimentais. Para o grupo com membrana foi utilizado o BioGide®. Doze cães foram submetidos a extrações dos pré-molares e primeiros molares mandibulares bilateralmente. Quatro meses após cinco defeitos ósseos (6 mm de diâmetro/4 mm de profundidade) foram confeccionados em um lado. Implantes de 3,3 x 10 mm foram instalados na mesial de cada defeito, proporcionando um \"gap\" distal de 2,7 mm. Os defeitos foram aleatoriamente preenchidos com Ab, Cg, BB, BC e BG. Os mesmos procedimentos foram executados no lado oposto após oito semanas. A membrana foi utilizada para recobrir os defeitos em metade dos lados. Os animais foram sacrificados após oito semanas. A estabilidade dos implantes foi aferida pelo Osstell Mentor®, na instalação do implante e no sacrifício. Os espécimes (n=60, sendo 3 de cada grupo) foram escaneados em micro-tomógrafo Skyscan® 1172. Após aquisição das imagens, o volume de interesse de 3,0 x 6,0 x 4,0 mm foi estabelecido e os parâmetros relativos à formação óssea foram avaliados. Todos os biomateriais foram escaneados in vitro para avaliação da porosidade. Utilizando a técnica de cortes por desgaste, lâminas histológicas foram confeccionadas para a avaliação histológica e histométrica de cada espécimen. As análises histométricas revelaram que o BC apresentou formação óssea semelhante ao Ab em 8 semanas sem BGd. O Cg mostrou a maior formação óssea entre os tratamentos testados em 16 semanas com BGd, e foi superior ao BB e BG em 8 semanas sem BGd (p<0,05). O BB exibiu pior formação óssea entre os tratamentos (8 e 16 semanas, com ou sem membrana). O BC obteve o melhor desempenho dentre os biomateriais. Todos os biomateriais foram parcialmente reabsorvidos de 8 a 16 semanas, no entanto, o BB foi encontrado em maior quantidade em comparação com os demais biomateriais (p<0,05). Em relação à análise da crista alveolar, o BB apresentou a menor reabsorção entre os tratamentos, com e sem BGd a 8 e 16 semanas (p<0,05). A aplicação da BGd proporcionou maior ISQ em 16 semanas, independentemente do material testado (p<0,05). A análise micro-tomográfica mostrou que quando a BGd não foi utilizada, o BG proporcionou a maior quantidade de osso no interior do defeito, seguido pelo BC (p<0,05). Quando o defeito foi coberto com BGd, o Ab rendeu superior formação óssea (p>0,05). A análise de superfície óssea mostrou valores aumentados em sítios tratados com BG, seguido por BC em 8 semanas sem BGd, e Ab em 8 semanas com BGd (p<0,05). O BC apresentou superfície/volume ósseo superior a 8 (com e sem BGd) e 16 semanas com BGd (p<0,05). O BB apresentou os menores valores em 16 semanas (sem BGd). O Cg em 16 semanas (com BGd) foi o pior entre os tratamentos aplicados (p<0,05). Em relação à espessura trabecular, Ab e BB apresentaram respectivamente valores maior e menor (p<0,05), independente do tempo experimental avaliado ou uso de membrana. A análise da porosidade dos biomateriais revelou que o BG apresentou maiores números, volume e superfície de poros fechados. O BB apresentou maiores valores de volume de poros abertos, porosidade aberta e porosidade total em comparação com os outros materiais. Conclui-se que a implantação de bloco de alta porosidade (BB) falhou em proporcionar maior reparo ósseo no interior do defeito e foi o tratamento que mais reduziu a reabsorção da crista óssea alveolar distal. Biomateriais com menor porosidade (BC e BG) apresentaram superior ou semelhante formação óssea e estabilidade dos implantes em comparação ao osso autógeno. A utilização da técnica de ROG melhorou o padrão de formação óssea em todos os tratamentos e períodos testados e reduziu a presença de tecido mole no interior do defeito. Uma relação inversa entre a porosidade dos biomateriais e a formação óssea in vivo foi observada no modelo experimental adotado. / The aim of this study was to compare the effectiveness of porous biomaterials in bone formation and repair of cervical mandibular defects in dogs, with or without Guided Bone Regeneration (GBR) technique. Bio-Oss Block® (BB), Bio-Oss Collagen® (BC), Bio-Oss® in granules (BG), autogenous bone (Ab) and coagulum (Cg) were used under the same experimental conditions. For the membrane group, BioGide® was used. Twelve dogs underwent bilateral extractions of mandibular premolars and first molars. After four months five bone defects (6 mm long / 4 mm deep) were prepared at one side. Implants of 3.3 x 10 mm were installed on each of mesial defect, providing a distal gap of 2.7 mm. The defects were randomly filled with Ab, Cg, BB, BC and BG. The same procedures were performed in the opposite side after eight weeks. A membrane was used to cover the defects in half of the sides. Animals were sacrificed after eight weeks. Implant stability was measured by Osstell Mentor®, at implant installation and sacrifice. The specimens (n=60, 3 in each group) were scanned in Skyscan® 1172 micro-CT scanner. A volume of interest of 3.0 x 6.0 x 4.0 mm was established and the parameters related to bone formation were evaluated. All used biomaterials were also scanned for in vitro porosity evaluation. Using Exakt® system, ground section of each specimen were prepared for histological and histometric assessment. Histometric analysis revealed that BC presented similar bone formation to Ab in 8 weeks without BGd. Cg showed greater bone formation between treatments at 16 weeks with BGd, and was superior to BG and BB at 8 weeks without BGd (p<0.05). BB exhibited worse bone formation within treatments (8 and 16 weeks, with or without membrane). BC had the best performance among biomaterials. All biomaterials were partially resorbed from 8 to 16 weeks. However, BB was found in greater amounts in comparison with other biomaterials (p<0.05). Regarding the alveolar crest analysis, BB had the lowest resorption between treatments with and without BGd at 8 and 16 weeks (p<0,05). The BGd use promoted higher final ISQ values at 16 weeks, regardless the tested treatment (p<0.05). Micro-CT analysis showed that when BGd was not used, BG yielded the highest amount of bone within the defect, followed by BC (p<0.05). When the defect was covered with BGd, Ab yielded higher bone formation (p>0.05). Bone surface area analysis showed that increased values in sites treated with BG, followed by BC without BGd at 8 weeks, and Ab at 8 weeks with BGd (p<0.05). The BC presented greater Bone Surface Area/Bone volume at 8 (with and without BGd) and 16 weeks with BGd (p<0.05). BB had the lowest values at 16 weeks (without BGd). Cg presented the worst performance among treatments at 16 weeks (with BGd) (p<0.05). Regarding the Trabecular Thickness, Ab and BB showed the highest and lowest values, respectively (p<0.05), regardless of the time point or membrane use. In biomaterials porosity analysis, BG showed higher numbers, volume, and surface area of closed pores. BB had the highest volume of open pores, open porosity and total porosity compared with the other treatments. It can be concluded the use of a high porosity block (BB) failed to provide greater bone formation within the defect area and it was the treatment that better reduced distal alveolar crest resorption. Biomaterials with lower porosity (BC and BG) showed higher or similar bone formation and implant stability if compared to autogenous bone. The appliance of BGd improved bone formation in all treatments and tested periods and reduced soft tissue presence within the defect. An inverse relationship between biomaterials\' in vitro porosity and in vivo bone formation was observed in the experimental model used.

O presente trabalho avaliou a formacao de tecido osseo ao redor de implantes osseointegraveis de titanio, apos realizacao de defeitos osseos, utilizando diferentes tipos de substitutos osseos. Foram utilizados 5 caes de raca indeterminada, os pre molares e molares mandibulares foram extraidos, passados 12 semanas, os caes foram submetidos a um novo procedimento cirurgico aonde foram realizadas as perfurações preconizados pelo fabricante dos implantes, o osso vestibular da mandibula foi desgastado ate que parte da perfuracao fosse exposta, os implantes entao foram colocados nas respectivas perfuracoes, ficando com 4 espiras expostas. Esses defeitos foram preenchidos aleatoriamente com Bioglass® 45S5, Biosilicato® , Osso autogeno, e sem nenhum material de preenchimento. 18 semanas depois da colocacao dos implantes os caes foram mortos e suas hemi-mandibulas contendo os implantes removidas e submetidas aos analises histologiaos e histomorfometricas, os dados obtidos foram submetidos ao teste de Kruskal-Wallis. A histologia dos 4 grupos estudados revelaram a presenca de tecido osseo maduro em contato com os implantes, porem sem ralacao direta com os vidros bioativos e osso autogeno. A porcentagem de contato osso implante, matriz ossea mineralizada ao redor da espira, e area de espelho, nao mostraram diferencas estatisticas significantes entre os 4 materiais testados. Os resultados indicam que a presenca de substitutos osseos nao interfere com a formacao ossea ao redor dos implantes nesse modelo experimental. E existe resposta tecidual muito semelhante entre o osso autogeno, Bioglass® 45S5 e Biosilicato. / The aim of the present study was to investigate the amount of bone formation on Ti implants in sites with intra-bony defects filled with different bone substitutes. Mandibular premolars and first molars were extracted from 5 dogs, and after 12 weeks 3 implants were bilaterally placed in sites with intra-bony defects and each implantation site randomly received the following treatment: Biosilicate®, Bioglass® 45S5, aoutologous bone or no treatment. At 18 weeks after implantation, the hemi-mandibles containing the implants were removed and processed for morphological and histomorphometric analysis. Data were submitted to Kruskal-Wallis and Fishers test. The histological sections of the 4 experimental groups exhibited mature bone tissue in contact with implants, but not related with bioactive glasses or autologous bone used. The percentage of bone-implant contact, mineralized bone matrix between implant threads, and mineralized bone matrix within mirror area in the treated or non-treated sites were not statistically different among the 4 experimental groups. These results indicates that the presence of the bone substitutes evaluated here did not interfere with bone formation on Ti implants in sites with intra-bony defects. In addition, tissue response to Biosilicate® was similar to that of Bioglass® 45S5 and autologous bone.

As alterações de superfície dos implantes de titânio (Ti) influenciam funções celulares e formação de tecido adjacente aos mesmos, mas é controverso se tais alterações trariam vantagens quando esses implantes fossem colocados em tecido ósseo de baixa qualidade. O objetivo deste estudo foi avaliar a resposta do tecido ósseo de baixa qualidade (tipo IV) a implantes de Ti com diferentes tratamentos de superfície. Para isso, implantes de Ti com superfície nanotexturizada (Ti-Nano), microtexturizada (Ti-Porous) e sem tratamento de superfície (Ti-Usinado) foram implantados em tíbias de coelhos. Após duas e seis semanas, o tecido ósseo formado ao redor dos implantes foi avaliado em cortes histológicos por desgaste e histomorfometricamente foram avaliados: a porcentagem de contato ossoimplante (BIC), porcentagem de área de osso mineralizado formado entre as espiras do implante (BABT), porcentagem da área de osso formada na área espelho (BAMA). Vários outros parâmetros morfométricos foram avaliados a partir de imagens e reconstruções tridimensionais obtidos por microtomografia. Ao final de seis semanas, foi avaliado o torque de remoção. Os resultados foram submetidos à análise de variância (ANOVA) com dois fatores de variação (tratamento de superfície e tempo de implantação) seguido do teste de Tukey (p&le;0,05). Apesar de algumas diferenças estatisticamente significantes para alguns dos parâmetros morfométricos, tais diferenças não são biologicamente importantes para que pudessem ser atribuídas aos tratamentos de superfície. Tanto que, histologicamente não se observou diferença nos padrões de formação óssea ou tipo de osso formado que pudesse ser associado aos tratamentos de superfície e o torque de remoção também não foi afetado pelos tratamentos. Em conclusão, esses resultados mostraram que os tratamentos de superfície, embora sejam na escala micrométrica ou nanométrica, não induzem repostas do tecido ósseo tipo IV diferentes daquelas induzidas por superfícies sem tratamento. / Some alterations in titanium (Ti) implant surfaces influence cell functions and tissue formation in areas adjacent to the implants, but it is controversial whether these changes would bring advantages when these implants were placed in bone of poor quality. The aim of this study was to evaluate the response of poor quality bone tissue (type IV) to Ti implants with different surface treatments. For this, Ti implants with nanotextured surface (Ti-Nano), microtextured (Ti-Porous) and without surface treatment (Ti-Machined) were implanted into tibias of rabbits. After two and six weeks, the bone tissue around the implants was assessed in undecalcified histological sections and histomorphometrical analysis to evaluate: the percentage of bone-implant contact (BIC), percentage of the area of mineralized bone formed between threads (BABT), the percentage area of bone formed in the mirror area (BAMA). Several other morphometric parameters were evaluated from images and three-dimensional reconstructions obtained by microtomography. At the end of six weeks the removal torque was evaluated. The results were subjected to analysis of variance (ANOVA) with two factors of variation (surface treatment and time) followed by Tukey test (p&le;0.05). Despite some statistically significant differences for some of the morphometric parameters, such differences are not biologically important and they could not be attributed to the surface treatments. In keeping with this, histological analysis failed to show any difference in bone formation that could be associated to the surface treatments and removal torque was not affected by treatments either. In conclusion, these results showed that the surface treatments, irrespective of being on the micrometer or nanometer scale, do not induce responses of type IV bone tissue different from those induced by untreated surfaces.

Abstract Type XIII collagen is a type II transmembrane protein which is expressed in many tissues throughout development and adult life. It is located in focal adhesions of cultured cells and in the adhesive structures of tissues such as the myotendinous junctions in muscle, intercalated discs in the heart and the cell-basement membrane interphases. To further characterize the function of this protein, we generated transgenic mice overexpressing it in normal and mutant forms. A large in-frame deletion in the COL2 domain of type XIII collagen led to synthesis of truncated α1(XIII) chains in transgenic mice, disrupting the assembly of normal type XIII collagen trimers. Fibroblasts derived from the mutant mice expressed shortened α1(XIII) chains, and no intracellular accumulation of the mutant protein was detected, suggesting that the mutant molecules were expressed on the cell surface. Transgene expression led to an embryonally lethal phenotype in offspring from heterozygous mating at two distinct stages of development. The early phenotype fetuses died due to the lack of chorioallantoic fusion and functioning placenta at 10.5 dpc, while the death of the late phenotype fetuses was caused by cardiac and placental defects around 13.5 dpc. The phenotype resembles closely several other cell adhesion molecule mutants, indicating that type XIII collagen has an essential role in certain adhesive interactions that are necessary for normal development. Mice overexpressing type XIII collagen with or without a point mutation developed postnatally an unexpected skeletal phenotype marked by a massive increase in bone mass. The cortical bone cross-sectional area and volumetric bone mineral density were highly increased, but trabecular bone volume was not significantly altered. The bone formation rate was several times higher in the mutant mice than in their normal littermates, while the osteoclast number and resorption activity were normal. Type XIII collagen was expressed highly in primary osteoblasts derived from the transgenic mice. Overexpression of type XIII collagen in osteoblasts enhanced both cell proliferation and differentiation while lack of it had opposite effects. Furthermore, mutant cells responded to mechanical strain differently than wild-type cells. The findings suggest that type XIII collagen has an important role in bone modeling, and it may in particular have a function in coupling the regulation of bone mass to mechanical usage.

Sclerosteosis is a severe autosomal recessive sclerosing skeletal dysplasia with no available treatment. It is characterised by excessive bone formation and is caused by mutations in the SOST gene that lead to loss of expression of sclerostin, a protein that acts as a negative regulator of bone formation by binding to low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6) Wnt co-receptors to inhibit the canonical Wnt/β-catenin signalling pathway. This study investigated the effectiveness of sclerostin replacement therapy in a mouse model of sclerosteosis. Recombinant wild type mouse sclerostin (mScl) and two novel mScl fusion proteins containing a C-terminal human immunoglobulin G1 (IgG1) antibody fraction crystallisable (mScl hFc), or C-terminal human Fc with a poly-aspartate motif (mScl hFc PD), to increase serum half-life and promote localisation to bone, respectively, were produced and purified using mammalian expression and standard chromatography techniques. These recombinant mScl proteins bound to LRP6 with high affinity (nM range) and completely inhibited matrix mineralisation in an in vitro bone nodule formation assay. Pharmacokinetic assessment following a single dose administered to wild type (WT) or SOST knock out (SOST-/-) mice indicated that the presence of the hFc increased protein half-life from less than 5 minutes to at least 1.5 days. The effect of a 6-week treatment with these proteins on the skeletal phenotype of young SOST-/- mice revealed that mScl hFc PD treatment resulted in a modest but significant reduction in trabecular bone volume compared with the vehicle control. There was no marked effect on cortical bone indices assessed by μCT, whole body areal bone mineral density by DXA, or terminal levels of the bone formation marker procollagen type 1 N-terminal propeptide (P1NP) in any of the SOST-/- or WT treatment groups, possibly due to insufficient exposure. Administration of recombinant mScl hFc PD protein partially corrected the high bone mass phenotype of the SOST-/- mouse, suggesting that bone-targeting of sclerostin engineered to improve half-life was able to negatively regulate bone formation in the SOST-/- mouse model of sclerosteosis. However, the modest efficacy indicates that sclerostin replacement may not be an optimal strategy to mitigate excessive bone formation in sclerosteosis, hence alternative approaches should be explored. / Thesis (PhD)--University of Pretoria, 2020. / UCB Pharma (Slough, UK) / National Research Foundation (NRF) / University of Pretoria (Pretoria, South Africa) / Paraclinical Sciences / PhD / Unrestricted