Made available in DSpace on 2014-10-09T12:38:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:39Z (GMT). No. of bitstreams: 1 05649.pdf: 6795207 bytes, checksum: c03839663e599700ba2154bbedff9b1c (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

O reparo Ãsseo à um processo multifuncional com a participaÃÃo de vÃrios mediadores. Dentre os fÃrmacos que interferem nesse processo, destaca-se o Ranelato de EstrÃncio (RSr), o qual apresenta um mecanismo de aÃÃo dual, estimulando a neoformaÃÃo ao mesmo tempo que inibe a reabsorÃÃo Ãssea. Para avaliar a capacidade osteoindutiva, modelos que favorecem o estudo do potencial de reparo Ãsseo local tÃm sido utilizados, tais como o de induÃÃo de defeitos de tamanhos crÃticos (CSD) em calvÃrias de ratos. O objetivo deste estudo foi avaliar o RSr no reparo Ãsseo de defeitos crÃticos de 8 mm de diÃmetro induzidos em calvÃria de ratos. Para tanto, imediatamente apÃs a cirurgia, os CSD receberam uma Ãnica aplicaÃÃo de RSr (2,1 e 6,3 mg) ou nenhum tratamento (Controle). Grupos de animais foram sacrificados a 0 h e aos 15, 45, 90 e 120 dias apÃs a induÃÃo do CSD e calvÃrias foram processadas para anÃlise macroscÃpica, por meio de Tomografia Computadorizada tipo Cone Beam (TCCB), histolÃgica (HE) e imunohistoquÃmica para RANKL e OPG. Na anÃlise por TCCB, verificou-se que, no grupo RSr 6,3 mg, o RSr causou reduÃÃo significativa da Ãrea do CSD aos 90 dias (67,79  2,32 mmÂ) e 120 dias (62,28  4,17 mmÂ), quando comparadas Ãs calvÃrias recÃm-induzidas (0 h) (78,61  0,96 mmÂ) (p<0,05), mas nÃo em relaÃÃo ao grupo Controle apÃs 90 dias (74,2  2,73 mmÂ) e 120 dias (72,04  1,74 mmÂ) (p>0,05). Na anÃlise histolÃgica das calvÃrias dos animais do grupo Controle foram observadas alteraÃÃes histolÃgicas significantes relacionadas ao reparo Ãsseo como neoformaÃÃo Ãssea restrita Ãs bordas do CSD quando comparados aos animais do grupo normal em todos os perÃodos experimentais (p<0,05). Os animais do grupo RSr (2,1 mg) nÃo apresentaram alteraÃÃes histolÃgicas significantes quando comparados ao grupo Controle em todos os perÃodos experimentais (p>0,05) enquanto que, nos animais do grupo RSr (6,3 mg), foram observados aspectos histolÃgicos compatÃveis com reparo Ãsseo aos 90 dias e aos 120 dias como neoformaÃÃo Ãssea em borda e no centro do CSD com diferenÃas significativas quando comparados aos grupos Controle ou RSr 2,1 mg (p<0,05). Complementando esses resultados, as calvÃrias dos animais apÃs 120 dias da aplicaÃÃo local de RSr (6,3 mg) apresentaram intensa imunoexpressÃo para OPG e negativa para RANKL, enquanto que as calvÃrias do grupo Controle apresentaram imunoexpressÃo moderada apenas para RANKL. Assim, pode-se concluir que o tratamento local com RSr evidenciou seu papel osteoindutor favorecendo a reparaÃÃo Ãssea do CSD pela modulaÃÃo da via RANKL/RANK/OPG. / The bone repair is a multifunctional process involving various mediators. Among the many drugs that interfere with this process, we highlight the Strontium Ranelate (SrR), which has a dual mechanism of action, stimulating neoformation at the same time, which inhibits bone resorption. To evaluate the osteoinductive capacity, models of study that investigate the potential for bone repair site have been used, such as induction of critical size defects (CSD) in rat calvaria. The aim of this study was to evaluate bone healing induced by SrR in critical defects of 8 mm in diameter in rat calvaria. For this purpose, immediately after surgery, the CSD received a single application of SrR (2.1 and 6.3 mg) or no treatment (Control). Groups of animals were sacrificed at 0 h and at 15, 45, 90 and 120 days after induction of CSD and calvarial samples were removed and processed for analysis by macroscopic type Cone Beam Computed Tomography (CBCT), histological (HE) and immunohistochemical for RANKL and OPG. In CBCT analysis, it was found that induction of CSD group SrR 6.3 mg caused a significant reduction of the areas of CSD at 90 days (67.79  2.32 mmÂ) and at 120 days (62.28  4.17 mmÂ) compared to calvariae newly induced (0 h) (78.61 mm  0.96) (p<0.05) but not compared to Control groups at 90 days (74.2  2.73 mmÂ) and at 120 days (72.04 Â1.74 mmÂ) (p>0.05). We observed in the histological analysis of calvariae of Control groups significant changes related to bone repair when compared to normal group (p<0.05). The animals that received SrR (2.1 mg) showed no significant histological changes, compared to the Control groups in all experimental periods (p>0.05), while animals of SrR 6.3 mg group showed significantly histological features consistent with bone repair at 90 days and at 120 days as neoformation in edge and center of the CSD when compared to Control or SrR 2.1 mg groups (p<0.05). To complement these results, the calvariae of animals after 120 days of topical application of SrR (6.3 mg) showed intense immunostaining for OPG and RANKL negative, whereas the calvariae of Control groups showed moderate immunoreactivity only for RANKL. Thus, it can be concluded that the local treatment with SrR (6.3 mg) revealed its role favoring osteoinductive bone repair by modulating the CSD RANK/RANKL/OPG.

Made available in DSpace on 2014-10-09T12:36:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:09Z (GMT). No. of bitstreams: 1 04226.pdf: 1346289 bytes, checksum: ae51647be934d5e52ce7e2787d3ee5b5 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:38:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:39Z (GMT). No. of bitstreams: 1 05649.pdf: 6795207 bytes, checksum: c03839663e599700ba2154bbedff9b1c (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

No description available.

This study is part of a project aiming for the long-term burying of nuclear wastes in Kincardine, Ontario. Bedrock formations as well as their associated waters were analyzed in drill cores from the Michigan sedimentary basin, southwest Ontario. This research utilizes geochemistry combined to strontium and rubidium isotope ratios in order to determine the origin of porewaters from Ordovician shales and limestones. It is demonstrated that these waters are the result of a mixing line between the Silurian (Guelph) and Cambrian groundwaters. This last end-member was also mixed with Precambrian brines to some extent. Strontium and rubidium isotopes also demonstrated rubidium in clays were leached by porewaters over time. Once in solution, radioactive rubidium decayed into strontium over time. This process explains the accumulation of radiogenic strontium observed in porewaters. An age estimate for the deposition of carbonates and other evaporates was calculated with the Rb-Sr isotope system. The calculated age is 453.7 million years before present for dolomites, which is consistent with the history of the site. It was possible to gen an approximate age of 339.7 million years for the formation of illites. This corresponds to the illitization process that occurred after the deposition of rocks, when the Silurian brines infiltrated the deeper Ordovician shale. It was also possible to estimate of porewaters ages.

A global legacy of radioactively contaminated land exists as a result of nuclear fuel cycle operations. Demonstration of the safe management of the UK nuclear legacy, including contaminated land, is important whilst the long term fate of legacy waste remains uncertain and the UK is moves towards new nuclear power. One aspect of nuclear contaminated land research focuses on the immobilisation of intermediate and long lived radionuclides that are mobile in groundwater and are migrating in the environment. At Sellafield nuclear facility, UK, strontium-90 and technetium-99 are found as co-contaminants in groundwater alongside the most abundant non radioactive contaminant, nitrate. Their differing radiochemical behaviour and the presence of nitrate presents a challenge for remediation strategies. Bioremediation has the potential for in-situ immobilization of 99Tc via reduction from mobile Tc(VII) to less mobile Tc(IV) concurrent with Fe(III) reduction. In this project bioreduction processes were investigated in sediment microcosms and model systems under variable pH and nitrate conditions and using microorganisms representative of the Sellafield site. Sediment bioreduction occurred via stimulation of the natural microbial community. Denitrification resulted a delay in the onset of metal reduction followed by a raised pH. At the mildly acidic pH of the natural sediments, a nitrate concentration of 100 mM caused bioreduction to stall. However, at pH 7, reduction of 100 mM nitrate resulted in a final pH > 9 and alkaline Fe(III) reduction. In bioreduced sediments, the microbial ecology was dominated by nitrate reducing microorganisms and Fe(III) reducing enrichment cultures were necessary to identify relevant alkaline Fe(III) reducing bacteria. Enrichment cultures isolated a novel alkali tolerant Fe(III) reducing Serratia sp. with a growth range of pH 4 to 9. Increased pH resulting from denitrification decreased the mobility of Sr2+ via increased sorption to mineral surfaces. X-ray absorption spectroscopy confirmed Sr2+ incorporation into carbonate mineral phases above pH 8.5. Model systems showed reductive removal of 99Tc from solution by an Fe(II) bearing mineral assemblage at both pH 7 and 9. In contrast Sr2+ remained in solution at pH 7 and precipitated as SrCO3 at pH > 8.5. This study for the first time demonstrates the effects of high nitrate on pH in Sellafield type sediments, alkaline Fe(III) reduction by a Serratia sp, the incorporation behaviour of Sr2+ during sediment bioreduction and the behaviour of Sr2+ and 99Tc in novel Fe(II) mineral bearing model systems. These findings improve the understanding of radionuclide migration at contaminated sites and inform possible engineered bioremediation scenarios.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1982. / Microfiche copy available in Archives and Science / Bibliography: leaves 226-235. / by Mark Albert Sneeringer. / Ph.D.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19297号 / 工博第4094号 / 新制||工||1631(附属図書館) / 32299 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 伊藤 禎彦, 准教授 藤川 陽子 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Three questions were asked during this research. 1) Does the Sr content of Caribbean speleothems have a direct relationship with the age of the host rock at the time of speleothem precipitation?; 2) do older speleothems contain less Sr than younger speleothems in the same climatic setting?; and 3) will speleothems record the change in Sr concentration of eogenetic carbonates as a faster depletion in climates of higher precipitation as opposed to drier climates? The speleothems and cave rocks in this study were analyzed with various methods in an attempt to understand the rock processes that affect speleothem Sr concentrations. Evidence to support the hypothesis that younger host rock contributes higher concentrations of Sr to speleothems was found in the stalagmites of Curacao while Bahamian stalagmites indicated climatic variations. The results have implications for using stalagmites from relatively young, eogenetic limestone as a proxy for Sr-related paleoclimate data.