No description available.

Osteoblastic cells respond to mechanical stimuli with alterations in proliferation and/or phenotypic expression. In some cases, these responses occur within only a few applications of stimuli (i.e. 'cycle-dependent trigger response') rather than in a dose-dependent manner. To explore potential mechanisms of the cycle dependent trigger response, we raised the following questions: (1) Does strain of bone cells alter gene expression; if so, how quickly does it occur and how long does it last? (2) Are alterations in message level strain magnitude dependent? (3) Are alterations in steady-state message levels cycle dependent? Cultures were evaluated for osteocalcin mRNA one week following a daily stretch application at four stretch magnitudes and four cycle numbers and compared to nonstretched controls. Steady state mRNA message was ascertained prior to and at 10, 20, 30, 60, 120, 180, and 240 min following initiation of stretch. Following mRNA isolation, first strand cDNA synthesis was performed and fluorometrically quantitated. A reverse transcriptase based PCR (RT-PCR) approach allowed assessment of osteocalcin mRNA levels from microcultures (50,000 cells per 10 μl culture or 5000 cells mm2) of rat calvarial osteoblasts. Optimized PCR was performed using primers to the bone specific protein, osteocalcin (OC) and two 'housekeeping' genes, β-actin and GAP-DH. PCR products were separated on 4% agarose gels and band intensities digitized with relative quantitation based on internal standards in each gel. The lowest magnitude of stretch (-1 KPa) at 1800 cycles per day reproducibly depressed message for osteocalcin, but not β-actin when assayed immediately following the cessation of strain application. By three hours following the initiation of stretch, message levels returned to control values. At the time of stretch cessation, the 1800 cycle stretch regimen diminished (p < 0.0001) steady-state osteocalcin message independently of the four stretch magnitudes. Stretch for 300 cycles failed to depress (p = 0.05) osteocalcin message cultures at any time, but 600 cycles depressed message by 30 min. By one and two hours, cultures stretched 600, 900, and 1800 cycles showed similar levels of message depression. Four hours following the initiation of stretch, message levels returning to nonstrained levels in all groups. We conclude that alterations in cell response to strain are in part mediated by gene expression, that alterations last 3-4 h in this system, and that the message mechanism itself exhibits a triggerresponse dependency to cycle number.

No description available.

Osteocalcin, which is produced by the osteoblast, and the urinary pyridinium compounds (pyridinoline and deoxypyridinoline), which are derived from collagen, are widely used as markers of bone turnover. Osteocalcin was extracted from bone in 20% formic acid and separated using a linear 4-60% acetonitrile gradient containing 0.1% TFA at a flow rate of 1ml/min. The standard curve was linear up to 15 <I>μ</I>g of osteocalcin injected, with inter- and intra-assay coefficients of variation of 6.9 and 8.8% respectively while recovery of osteocalcin added to bone extracts averaged 102.7 ± 6.16 %. Having developed this assay it was then used in a series of experiments designed to study the biological function of osteocalcin in bone. Plasma osteocalcin levels decreased with age and showed large between-animal variations; the variability over 24 h was also large but there was no evidence of consistent circadian rhythm. In bone, changes in osteocalcin levels tended to parallel those for calcium whereas pyridinium crosslink levels tended to increase with age. Neither were sufficiently sensitive to detect differences in bone turnover in lambs of the same age but growing at different rates though osteocalcin levels in blood and in bone were sensitive to P-deficiency in sheep but not in pigs and there was little evidence indicating that osteocalcin plays any direct role in the mineralisation process. In separate studies adult sheep were treated with a bone antiresorptive agent, Ibandronate, and its effects on the metabolism and excretion of the pyridinium crosslinks was examined. At rates which have been shown to be effective in reducing bone resorption in humans this compound had little effect on the overall rate of excretion of these crosslinks in these sheep but did alter the proportions excreted in free or in peptide bound form.

Thesis (Ph.D.)--McMaster University, 2003. / Advisor: Daniel Yang. Includes bibliographical references (leaves 88-97). Also available via World Wide Web.

abstract: The gold standard for bone measurement is DXA (dual energy X-ray absorptiometry). Typically, to observe changes in bone by DXA, a minimum of a 4-month intervention is required. Serum osteocalcin (OST) (a bone formation marker) and quantitative ultrasound (QUS) of the calcaneus can be used as indicators of bone change but the sensitivity and time course of these indices to short term interventions are unknown. The purpose of this study was twofold: to compare monthly changes in OST and QUS in response to jump training and to evaluate the relationship between DXA, OST and QUS. Young women with QUS t-scores less than 1.0 were randomized into a jump training (J) (n=16) or control (C) (n=16). J consisted of a progressive routine of 1 and 2-footed jumping performed 3 days per week for 4 months. Body composition, QUS and OST were measured at baseline, and monthly for 4 months. DXA and 24-hour dietary recalls were completed at baseline and 4 months. Low attrition rate (12.5%) and high compliance (98%) with the exercise intervention was recorded. No significant correlations between QUS and OST existed. No significant differences were observed between groups at baseline in body composition or bone variables. Monthly increases in OST were observed but there were no significant differences over time between groups in any bone variables. OST and QUS may be indicative of short term bone changes but these variables were not specifically sensitive to the jumping intervention in this population of women. / Dissertation/Thesis / Ph.D. Physical Activity, Nutrition and Wellness 2011

Made available in DSpace on 2014-06-11T19:27:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-02Bitstream added on 2014-06-13T20:57:16Z : No. of bitstreams: 1 tera_tm_me_sjc.pdf: 2944672 bytes, checksum: 538ffaa6e20676a8e7a52d38fd5e1b66 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estudo avaliou a expressão imunoistoquímica dos marcadores de formação óssea Osteocalcina (OCC), Osteonectina (ONC) e Sialoproteína Óssea (BSP), e do marcador de reabsorção óssea Ligante do Receptor Ativador do Fator Nuclear Kappa-β (RANKL) no processo de reparo do enxerto ósseo autógeno em bloco, recoberto ou não por membrana de Politetrafluoretileno expandido (PTFE-e), em ratas com deficiência estrogênica induzida. Para tanto, foram avaliadas espécimes de Enxerto Ósseo Autógeno (EOA) recobertos ou não por membrana de PTFE-e, provenientes de 80 ratas, divididas aleatoriamente em 2 grupos (OVZ e SHAM). As 40 ratas pertencentes ao grupo OVZ foram submetidas à cirurgia de ovariectomia e as 40 do grupo SHAM à cirurgia de ovariectomia simulada. Os dois grupos foram subdivididos em E, onde foi realizada cirurgia para colocação de EOA, e grupo ME, onde o EOA foi recoberto por membrana de PTFE-e. Os períodos avaliados foram dia 0, 7, 21, 45 e 60 dias. Os espécimes foram incluídos em parafina, para realização de cortes seriados com 3 μm de espessura, que foram estendidos em lâminas previamente tratadas pelo 3-aminopropiltrietoxisilano e então foram submetidos à técnica imunoistoquímica para os marcadores OCC, BSP, ONC e RANKL. Os resultados mostraram marcação mais intensa da BSP nos dias 7 e 21. No sétimo dia, observou-se marcação intensa da ONC e RANKL, enquanto a OCC mostrou maior positividade nos dois últimos períodos. No último período avaliado, as características de marcação quanto à intensidade e às estruturas marcadas se assemelharam com os períodos iniciais para todos os marcadores. Os resultados permitiram concluir que o metabolismo ósseo foi mais intenso entre os dias 7 e 21, enquanto a maior taxa de remodelação foi observada aos 7 dias. A partir do 45º dia, o osso neoformado já exibia características de osso maduro. A expressão... / The study evaluated the immunohistochemical expression of bone formation markers Osteocalcin (OCC), Osteonectin (ONC) and Bone Sialoprotein (BSP) and the marker of bone resorption Receptor Activator of Nuclear Factor Kappa-β Ligand (RANKL) in the repair process autogenous bone grafts in blocks covered or not by polytetrafluoroethylene membrane (PTFE-e), in rats with estrogen deficiency induced. For this, 80 famale rats were divided randomly into two groups (SHAM and OVZ). The 40 rats in the group OVZ underwent surgical ovariectomy and 40 of the SHAM group underwent to surgical sham ovariectomy. The two groups were subdivided into E, where surgery was performed for placement of ABG, and ME group, where the ABG was covered with PTFE-e membrane. The evaluation periods were days 0, 7, 21, 45 and 60 days. The specimens were embedded in paraffin, to perform serial sections with 3 mm thick, which were extended on slides previously treated by 3-aminopropiltrietoxisilano and then were subjected to immunohistochemical technique for th markers for the OCC, BSP, ONC and RANKL. The results showed more intense labeling of the BSP on days 7 and 21. On the seventh day, there was intense labeling of the ONC and RANKL, while the OCC showed higher positivity in the last two periods. In the last period evaluated, the characteristics of marking on the intensity and the structures resembled marked with initial periods for all markers. The results showed that the bone metabolism was most intense between days 7 and 21, while the highest rate of remodeling was observed at 7 days. From the 45th day, the newly formed bone already displayed characteristics of mature bone. The expression of immunohistochemical markers was not altered by estrogen deficiency, but rather by the presence of PTFE-e membrane

Resumo: O estudo avaliou a expressão imunoistoquímica dos marcadores de formação óssea Osteocalcina (OCC), Osteonectina (ONC) e Sialoproteína Óssea (BSP), e do marcador de reabsorção óssea Ligante do Receptor Ativador do Fator Nuclear Kappa-β (RANKL) no processo de reparo do enxerto ósseo autógeno em bloco, recoberto ou não por membrana de Politetrafluoretileno expandido (PTFE-e), em ratas com deficiência estrogênica induzida. Para tanto, foram avaliadas espécimes de Enxerto Ósseo Autógeno (EOA) recobertos ou não por membrana de PTFE-e, provenientes de 80 ratas, divididas aleatoriamente em 2 grupos (OVZ e SHAM). As 40 ratas pertencentes ao grupo OVZ foram submetidas à cirurgia de ovariectomia e as 40 do grupo SHAM à cirurgia de ovariectomia simulada. Os dois grupos foram subdivididos em E, onde foi realizada cirurgia para colocação de EOA, e grupo ME, onde o EOA foi recoberto por membrana de PTFE-e. Os períodos avaliados foram dia 0, 7, 21, 45 e 60 dias. Os espécimes foram incluídos em parafina, para realização de cortes seriados com 3 μm de espessura, que foram estendidos em lâminas previamente tratadas pelo 3-aminopropiltrietoxisilano e então foram submetidos à técnica imunoistoquímica para os marcadores OCC, BSP, ONC e RANKL. Os resultados mostraram marcação mais intensa da BSP nos dias 7 e 21. No sétimo dia, observou-se marcação intensa da ONC e RANKL, enquanto a OCC mostrou maior positividade nos dois últimos períodos. No último período avaliado, as características de marcação quanto à intensidade e às estruturas marcadas se assemelharam com os períodos iniciais para todos os marcadores. Os resultados permitiram concluir que o metabolismo ósseo foi mais intenso entre os dias 7 e 21, enquanto a maior taxa de remodelação foi observada aos 7 dias. A partir do 45º dia, o osso neoformado já exibia características de osso maduro. A expressão... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The study evaluated the immunohistochemical expression of bone formation markers Osteocalcin (OCC), Osteonectin (ONC) and Bone Sialoprotein (BSP) and the marker of bone resorption Receptor Activator of Nuclear Factor Kappa-β Ligand (RANKL) in the repair process autogenous bone grafts in blocks covered or not by polytetrafluoroethylene membrane (PTFE-e), in rats with estrogen deficiency induced. For this, 80 famale rats were divided randomly into two groups (SHAM and OVZ). The 40 rats in the group OVZ underwent surgical ovariectomy and 40 of the SHAM group underwent to surgical sham ovariectomy. The two groups were subdivided into E, where surgery was performed for placement of ABG, and ME group, where the ABG was covered with PTFE-e membrane. The evaluation periods were days 0, 7, 21, 45 and 60 days. The specimens were embedded in paraffin, to perform serial sections with 3 mm thick, which were extended on slides previously treated by 3-aminopropiltrietoxisilano and then were subjected to immunohistochemical technique for th markers for the OCC, BSP, ONC and RANKL. The results showed more intense labeling of the BSP on days 7 and 21. On the seventh day, there was intense labeling of the ONC and RANKL, while the OCC showed higher positivity in the last two periods. In the last period evaluated, the characteristics of marking on the intensity and the structures resembled marked with initial periods for all markers. The results showed that the bone metabolism was most intense between days 7 and 21, while the highest rate of remodeling was observed at 7 days. From the 45th day, the newly formed bone already displayed characteristics of mature bone. The expression of immunohistochemical markers was not altered by estrogen deficiency, but rather by the presence of PTFE-e membrane / Orientador: Maria Aparecida Neves Jardini / Coorientador: Renata Falchete do Prado / Banca: Andréa Carvalho de Marco / Banca: Yasmin Rodarte Carvalho / Mestre

Das Ziel der vorliegenden Arbeit war es, die Wachstumsbedingung der nicht kollagenen Knochenproteine auf unterschiedlichen Konversionsoberflächen zu untersuchen. Dazu wurde das Proliferations- sowie Apoptoseverhalten der Knochenproteine in vitro bestimmt. Es kamen neben dem Probekörper Titan als Negativstandard und Ticer als Positivstandard, vier weitere Probekörper auf Titanbasis mit unterschiedlicher Kalzium-Phosphorrelation zur Anwendung. Diese wurden mit humanen Knochenzellen beschickt und über einen Zeitraum vom 3., 5., 7., und 10. Versuchstag ausgewertet. Die Zellkerne und Apoptosefragmente wurden immunhistochemisch markiert und fluoreszenzoptisch untersucht. Desweiteren wurden die relativen Grauwerte ermittelt, welche die Intensität des Bildes wiedergeben. Es zeigte sich in überwiegenden Fällen eine Zunahme der Zellanzahlen auf den verschiedenen Probekörpern. Dagegen verhielt sich die Zahl der apoptotischen Fragmente invers, indem sie auf ein Minimum absanken. In unserer Arbeit kommen wir zu der Annahme, dass Oberflächenmodifikationen die Knochenmineralisierung in der Phase der Knochenneubildung um das Implantat herum, respektive um die Oberflächenstruktur des Implantates, signifikant verbessern. Durch die Beschichtung der Implantatoberflächen mit Kalzium-Phosphor wird einerseits die Oberflächenrauigkeit erhöht, andererseits die Anbindung vom Implantat an die Knochenstruktur verbessert.

Mit zunehmender Etablierung der Implantattherapie im zahnärztlichen Alltag stellt die Reduzierung der Einheilzeit durch Oberflächenoptimierung eine der Hauptbestrebungen der forschenden Industrie dar. Dazu treten ästhetische Patientenwünsche nach „weißen“ Materialien, die am ehesten durch das jedoch frakturgefährdete Zirkonmischoxid zu realisieren sind. Ziel der vorliegenden Arbeit war die Untersuchung der Osteokompatibilität verschiedener, metallener Probekörper mit „Zirkoniummischoxidbeschichtung“, in der humanen enoralen Knochenzellkultur. Unter Verwendung einer männlichen Knochenzellkultur über 10 Tage wurden die Expressionen der nonkollagenen Knochenmatrixproteine, Osteocalcin, Osteonectin und Bone Sialo Protein sowie des Wachstumsfaktors TGF-β auf 3 Standardoberflächen und 5 experimentell hergestellten Zirkoniummischoxidoberflächen bestimmt. Es galt zu ermitteln, ob die chemische Zusammensetzung und die Mikrostruktur der getesteten Probekörper Einfluss auf die Proteinexpression haben. Die gewonnenen Versuchsergebnisse lassen vermuten, dass vor allem die Oberflächenkonfigurationen der Experimentaloberflächen 3 (ZSG ½), 4 (ZS4-0,5) und 5 (ZS4-2) die Sekretion o.g. Knochenproteine im Vergleich zu den anderen Experimentaloberflächen sowie dem metallenen Positivstandard (PK7) und dem Negativstandard (PK8) begünstigen. Des Weiteren kann für den als keramischen Positivstandard verwendeten CERCON® Probekörper (PK6) auf Grund der Ergebnisse eine gute biologische Eignung in vitro angenommen werden. Von weiteren Versuchen, welche mit mind. 6 Probekörpern pro Standzeit und Marker durchgeführt werden sollten, lässt sich keine der verwendeten Experimentaloberflächen gerechtfertigt ausschließen.