Made available in DSpace on 2014-10-09T12:50:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:42Z (GMT). No. of bitstreams: 1 10559.pdf: 4689225 bytes, checksum: 0bad37f0403f5b41f76a16f6038c7ecd (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:35:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:36Z (GMT). No. of bitstreams: 0 / Staphylococcus aureus é um dos principais microorganismos causadores de infecção em humanos, podendo causar inclusive bacteremia e endocardite nos indivíduos infectados. Diversas cepas desta bactéria apresentam resistência a diferentes tipos de antibióticos, dentre eles os antibióticos meticilina e amoxicilina, como no caso da bactéria Staphylococcus aureus resistente à meticilina (MRSA). A Proteína ligadora de Penicilina 2a (PBP2a) é a enzima responsável por conferir resistência para a MRSA aos antibióticos β-lactâmicos, sendo uma molécula promissora para terapia com AcM. No entanto, além das terapias os métodos de diagnóstico também são ineficientes, pois atualmente o diagnóstico leva vários dias para produzir um resultado confiável. O objetivo deste trabalho foi desenvolver um radiofármaco utilizando o AcM anti-PBP2a, desenvolvido em Bio-Manguinhos/FioCruz, marcado com 99mTc, para identificação in situ do foco infeccioso causado por MRSA. Neste trabalho, incialmente o AcM anti-PBP2a foi reduzido com o agente redutor 2-mercaptoetanol (2-ME), para gerar grupos sulfidrilas (- SH). Logo após foram utilizados dois diferentes métodos da Marcação Direta: o Método 1, utilizando o reagente tartarato e o ácido gentísico, que atuam como agente transquelante e estabilizador, respectivamente; e o Método 2, utilizando um kit comercial de MDP, no qual o MDP atua como agente transquelante. Após a marcação do anticorpo, o radiofármaco foi submetido a ensaios de avaliação funcional, utilizando os métodos de eletroforese em gel SDS-PAGE não redutor; Immunoblotting; ELISA e o Ensaio de Neutralização in vitro. Como resultado foi visto que a quantidade média de grupos sulfidrilas produzida por AcM foi considerada satisfatória, cerca de 5 grupos SH por IgG, utilizando para isto a relação molar de 6.500:1 de 2-ME:AcM. O Método 2 foi o método que obteve melhor rendimento de marcação, com 73,5%, apresentando boa estabilidade depois de 2 horas (73,2%). A melhor formulação utilizada foi a seguinte: 0,5 mg de AcM anti-PBP2a; 10 μL do kit do MDP, depois de ser resuspendido com 5 mL de solução salina; e 75,48 MBq (2,04 mCi) de 99mTc, a reação ocorrendo em 15 minutos. Os Ensaios de Avaliação Funcional demonstraram que o AcM manteve a especificidade e afinidade de ligação à PBP2a. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:32:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:00Z (GMT). No. of bitstreams: 1 03361.pdf: 1482624 bytes, checksum: 301169dabd51ee9ab96e581d6e7d820b (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

In 1896, Becquerel discovered the natural radioactivity in potassium uranyl sulphate. Since then, Pierre and Marie Curie, E. Rutherford and F. Soddy all made tremendous contributions to the discovery of many other radioactive elements. The work of all these scientists has shown that all elements found in nature with an atomic number greater than 83 (bismuth) are radioactive. Artificial radioactivity was first reported by I. Curie and F. Joliot in 1934. These scientists irradiated boron and aluminium targets with a particles from polonium and observed positrons emitted from the target even after removal of the a particle source. This discovery of induced or artificial radioactivity opened up a brand new field of tremendous importance. Around the same time, the discovery of the cyclotron, deuteron and neutron by various scientists facilitated the discovery of many more artificial radioactivities. At present time more than 2700 radionuclides have been produced artificially in the cyclotron, the nuclear reactor, the neutron generator and linear accelerator. Radiopharmaceuticals are drugs that contain a radionuclide and are used for imaging if the radionuclide is a photon emitter (gamma-g or positron-b+) or for therapy if the radionuclide is a particle emitter (alpha-a or beta-b- or Auger/conversion e-). / Prof. A. Roodt

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.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.

Thesis (M.S. in environmental Science)--Washington State University, December 2007. / Includes bibliographical references (p. 27).