Low Temperature Nuclear Orientation (LTNO) is an important technique in the study of nuclei far from stability. The theory of LTNO and its application to the measurement of static nuclear moments and other quantities of spectroscopic interest are reviewed. The off-line facility at Oxford was used to study the decay of ¹³³I→¹³³Xe and ¹³⁵I→¹³⁵Xe. ¹³³I having Z=53 and N=80 has three protons above the closed shell Z=50 and two neutrons holes in N=82 shell, while ¹³⁵I has fully closed neutron shell since it has N=82, and they are of considerable theoretical interest since a wide variety of the theoretical nuclear models may be used to describe the observed levels close to the stable double closed shell structure. Another aim is to search for the nuclear magnetic dipole moment of the ground state of ¹³⁵I. Nuclear orientation of ¹³³IFe and ¹³⁵IFe enabled the mixing ratios of several transitions in the decay scheme of ¹³³I and ¹³⁵I to be determined. From temperature dependence for ¹³⁵I, the nuclear magnetic moment of ¹³⁵I has been deduced. Also temperature dependence for ¹³³I, analysed using a simple model, gave value for the magnetic hyperfine field that differed from previous published values. The method of combining nuclear orientation with NMR has become a very popular technique in recent years for determining nuclear magnetic dipole moments very precisely. The purpose of the NMR/ON experiment was to measure the hyperfine field with greater precision and to get some idea of the proportion of nuclei subject to it. Light Eu and Sm nuclei have attracted attention as systems with the number of protons right below the Z=64 subshell gap and the number of neutrons approaching N=82 major shell closure. Odd-proton, odd-neutron and odd-odd nuclei near the A=140 region have been investigated in the framework of the particle-triaxial rotor model. Main attention has been paid to explanation of experimental magnetic dipole and electric quadrupole moments of ground and isomeric states. Model predictions for deformation parameters of ^136-142Sm even-even cores have been extracted.

Size selective reactivity has been observed in pure aluminum cluster anions as a result of Lewis acid and base pairs. Using this a starting point, the goal of this study has been to explore how reactivity is affected with the addition of one or more ligand, which may induce active sites on the surface of the metal clusters. To study this, a theoretical investigation was undertaken on Al13Ix- and Al14Iy- (x=0-2, y=2-4) and their reactivity with methanol. The hypothesis was that iodine can induce a Lewis base site on the opposite side of the cluster, which may enhance reactivity. In results that are consistent with preliminary experimental data, it was found that the Al13Ix- series has a large energy barrier with respect to the cleavage of the O-H bond of methanol. The clusters of the series act as an extremely poor Lewis acids, and as a result, these clusters are relatively inert to methanol etching. On the other hand, the Al14Iy- series has a low barrier and is expected to react rapidly with methanol. The series is found to be most reactive at an aluminum adatom that is bound to an iodine due to the iodine extracting charge from the aluminum cluster creating a strong Lewis acid site.

This thesis concerns the development of metal-free applications using diaryliodonium salts. The first project describes an arylation protocol of allylic and benzylic alcohols in aqueous media. The method proceeds under mild conditions and the ether products were obtained in moderate to good yields. The methodology was also expanded to include arylation of phenols, giving diaryl ethers in good to excellent yields. In the second project, an arylation method that included a wider range of aliphatic alcohols was developed. The scope of accessible alkyl aryl ethers was studied and included a comparative study of phenylation and nitrophenylation of various alcohols. Finally, a formal metal-free synthesis of butoxycain was performed, illustrating the applicability of the developed method. The third project focused on the limitations and side reactions occurring in Chapter 2 and 3. First, an approach to access symmetric diaryl ethers via arylation of hydroxide was presented. This reaction gave rise to a number of side products, which we hypothesized to originate from aryne-type intermediates. A mechanism for the formation of these side products was suggested, supported by trapping and deuterium labeling experiments. Oxidation of the alcohol to the corresponding ketone was also observed and the mechanism of this interesting side reaction was investigated. The latter was suggested to proceed via an intramolecular oxidation without the involvement of radicals or arynes. The fourth project covers a method to synthesize highly sterically congested alkyl aryl ethers via arylation of tertiary alcohols using diaryliodonium salts. The method displayed a broad scope of tertiary alcohols and was also suitable for fluorinated alcohols. The final project detailed in this thesis deals with C-arylation with diaryliodonium salts, showcasing nitroalkanes as well as a nitro ester as suitable nucleophiles for metal-free arylation. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

Master of Science / Department of Animal Sciences and Industry / Robert Goodband / Three experiments used 1,756 pigs to evaluate the effects of corn dried distillers grains with solubles (DDGS) varying in oil content on growth performance, carcass characteristics, and fat quality in growing-finishing pigs. A fourth experiment used 12 pigs and determined the energy concentration and nutrient digestibility of the DDGS sources used in the previous 3 growth studies. Lastly, a fifth experiment used 576 pigs to determine the effects of DDGS and wheat middlings (midds) withdrawal 24 d before harvest in diets without or with ractopamine HCl (RAC) on growth performance, carcass characteristics, fat quality, and organ/intestine weights. Experiment 1 determined that increasing 7.4% oil DDGS decreased (linear, P < 0.02) ADG and G:F. Also, final BW, HCW, and carcass yield decreased (linear, P < 0.03), but jowl iodine value (IV) increased (linear, P < 0.001) as DDGS increased. Experiments 2 and 3 utilized DDGS sources that contained 5.2 vs. 9.3, and 9.2 vs. 11.8% oil, respectively. In brief, results suggested that while ADG was unaffected, feeding DDGS with 5.2% oil reduced G:F. In Exp. 4, stepwise regression was used to develop prediction equations based to determine that a 1% change in oil content of DDGS will change the DE by 71 kcal/kg and NE by 118 kcal/kg. Experiment 5 determined that pigs fed corn-soy (CS) diets throughout the finishing phase had greater (P < 0.03) ADG, G:F, and carcass yield and lower (P < 0.01) IV than those fed high fiber (HF; DDGS and wheat midds) diets throughout, with pigs fed the fiber withdrawal intermediately. Pigs fed RAC had greater (P < 0.01) ADG, G:F, and carcass yield than pigs not fed RAC. Iodine values were lowest (P < 0.01) for pigs fed the CS diets, highest (P < 0.01) for those fed HF diets throughout, and intermediate for pigs fed the withdrawal diet. Withdrawal of the HF diet to a CS diet partially mitigated negative effects on carcass yield and IV, and feeding RAC, regardless of dietary fiber regimen, improved growth performance and carcass yield.

Dans le milieu marin, les émissions biogéniques de composés iodées jouent un rôle essentiel dans le cycle biogéochimique de l’iode. Cependant les processus enzymatiques responsables de l'absorption, du stockage ou de la synthèse de métabolites iodés restent mal connus chez les chez les organismes marins, et plus encore chez les bactéries. Plusieurs gènes, potentiellement impliqués dans le métabolisme de l’iode, ont été identifiés dans le génome de la bactérie marine, Zobellia galactanivorans, dont celui codant une iodoperoxydase à vanadium (VIPO), enzyme spécifique de l'oxydation des iodures. La partie principale du projet de thèse a consisté à comprendre les mécanismes moléculaires contrôlant la spécificité pour certains halogénures des haloperoxydases à vanadium, en étudiant la VIPO de Z. galactanivorans par des approches de mutagénèse dirigée et de biologie structurale. Les douze enzymes mutantes produites et caractérisées au niveau biochimique montrent soit une perte d’activité, soit des modifications de leurs propriétés catalytiques, soit encore une faible activité bromoperoxydase. Les enzymes sauvage et mutantes ont également été étudiées par diffraction et absorption des rayons X, afin de relier les modifications structurales à leurs propriétés catalytiques. Les résultats suggèrent que le principal facteur modulant la spécificité chez ces enzymes est le potentiel d’oxydoréduction de l’intermédiaire réactionnel, le peroxovanadate. Des analyses biochimiques ont aussi été entreprises pour deux autres protéines identifiées sur le génome de Z. galactanivorans. La première protéine s’est révélée être une seconde VIPO. Pour la deuxième protéine, similaire à une iodotyrosine déiodinase, l’activité biochimique reste encore à être caractérisée. Z. galactanivorans posséderait plusieurs enzymes pouvant oxyder l’iodure, ainsi qu’une permettant de cliver les liaisons C-I. En parallèle à ce travail, la localisation et la spéciation de l’iode ont été étudiées par imagerie chimique chez Z. galactanivorans et chez l’algue brune, Laminaria digitata, connue pour ses fortes teneurs en iode. Les résultats de ce travail apportent un nouvel éclairage sur les mécanismes contrôlant la spécificité des haloperoxydases à vanadium envers les halogénures, et également sur l’origine bactérienne de cette famille d’enzymes. Plus globalement, ces études permettent de mieux appréhender le rôle du métabolisme de l’iode chez certaines bactéries marines et leurs importances dans le cycle biogéochimique de l’iode. / In marine environment, biogenic emissions of iodinated compounds play an essential role in biogeochemical cycle of iodine. Nevertheless, enzymatic process involved in absorption and storage of iodine or in the synthesis of iodinated compounds are unknown marine organisms, especially in bacteria. Several genes, potentially involved in iodine metabolism, have been identified in the genome of a marine bacterium, Zobellia galactanivorans. One of these genes codes for a vanadium iodoperoxydase (VIPO), an enzyme specific of iodide oxidation. The main part of the thesis project was to understand molecular mechanisms controlling the specificity vanadium halopéroxydase (VHPO) for some halide, by studying the VIPO from Z. galactanivorans by directed mutagenesis and structural biology. To lead this project, twelve mutated enzymes were produced and characterized at biochemical level. For some of them, mutations lead to a loss of activity or to modification of catalytic properties or to a slight VBPO activity. The wild type enzyme and three mutants were also analyzed by X ray absorption and diffraction spectroscopy in order to link the structural modifications to their catalytic properties. The results of this study suggest that the main factor modulating the specificity in these enzymes is modification of redox potential of the peroxovanadate. Biochemical analyses lead with two other proteins identified in the genome of Z. galactanivorans. The first protein was characterized as a new VIPO. For the second protein, similar to mammal iodotyrosine deiodinase, the biochemical activity remains to be characterized. Z. galactanivorans seems to have several enzymes which oxidize iodide or split C-I bond. In parallel at this work, the localization and speciation of iodine were analyzed by chemical imaging in Z. galactanivorans and in the kelp L. digitata, known to concentrate highly iodide. All this information allow to a better understanding of molecular mechanisms involved in the specificity for halide in VHPO and the bacterial origin of these proteins. More generally, these studies assess to understand the role of iodine metabolism in some marine bacteria and there role in biogeochemical cycle of this element.

O iodeto reduz a expressão, cauda poli(A) e taxa de tradução do mRNA da NIS, a partir de 30 min de tratamento. O estudo atual objetivou caracterizar as bases moleculares envolvidas nesses efeitos inibitórios. Células PCCl3 foram tratadas com NaI (10-3M), por diferentes períodos de tempo, e avaliou-se: a meia-vida do mRNA de NIS; o papel das porções 3\'UTR/5\'UTR; o envolvimento de eventos transcricionais; a organização do citoesqueleto de actina; o conteúdo total, meia-vida, degradação, internalização e atividade de NIS; a ativação da via PI3K/Akt. Os resultados evidenciaram que o excesso de iodeto: reduz a meia-vida e interage com a porção 3\'UTR do mRNA de NIS; inibe a atividade do promotor de NIS; desorganiza o citoesqueleto de actina; reduz o conteúdo total, de membrana, a meia-vida e atividade de NIS; aumenta a internalização de NIS por clatrinas, e sua degradação por lissosomos; ativa a via PI3K/Akt. Conclui-se que o iodeto ativa diferentes mecanismos moleculares, transcricionais e pós-transcricionais, para promover o efeito inibitório sobre a expressão de NIS. / Iodide reduces NIS mRNA expression, poly(A) tail length and transcription rate, after 30 min of treatment. The present study aimed to caracterize the molecular basis involved in these inhibitory effects. PCCl3 cells were treated with NaI (10-3M) and assays were performed to evaluate: NIS transcript half-life; the role of NIS mRNA 3\'UTR/5\'UTR; the involvement of transcriptional events; the organization of actin cytoskeleton; the total content, half-life, degradation, internalization and activity of NIS; the activation of PI3K/Akt pathaway. The results indicatred that iodide excess: reduces NIS transcript half-life and interacts with its 3\'UTR portion; inhibits NIS promoter activity; disrupts the actin cytoskeleton; reduces NIS total and membrane content, NIS half-life and NIS activity; induces the internalization of NIS through clathrin and its degradation through lisosomes; activates the PI3K/Akt pathway. In conclusion, iodide activates different molecular mechanisms, transcriptional and post-transcriptional, to promoter the inhibitory effect on NIS expression.

Linfomas são doenças originárias do sistema linfático, descritos por Thomas Hodgkin em 1932. São tradicionalmente classificados em dois grupos básicos: doenças de Hodgkin e linfomas do tipo não hodgkin (LNH). Inicialmente, pacientes com LNH foram tratados com radioterapia apenas ou combinada com imunoterapia usando-se anticorpo monoclonal anti-CD20 (ex., Rituximab-Mabthera, Roche). Porém, radioimunoterapia é uma nova modalidade de tratamento para pacientes portadores de LNH, na qual radiação citotóxica proveniente de radioisótopos terapêuticos é depositada nos tumores via anticorpos monoclonais (Acms). Este estudo concentrou-se nas condições de marcação do Acm anti-CD20 (Rituximab-Mabthera, Roche), com radioiodo (131I), pelo método direto, usando-se Cloramina-T como agente oxidante. Foram estudados parâmetros de marcação tais como: método de purificação, influência de tempo de incubação, influência de massa de agente oxidante, estabilidade in vitro e in vivo, imunoreatividade do anticorpo e distribuição biológica do anticorpo marcado em camundongos Swiss sadios. Produto de alta pureza radioquímica foi obtido, sem diferença notável entre os métodos aplicados. Não foi observada nenhuma influência direta do tempo de incubação na pureza radioquímica do anticorpo marcado. Um pequeno decréscimo na pureza radioquímica foi observado quando variou-se a massa do Acm sem variar a atividade do radioiodo. Após purificação, o anticorpo marcado apresentou pureza radioquímica de aproximadamente 100 %. Observou-se um produto de alta pureza radioquímica quando o anticorpo foi marcado na condição padrão. O anticorpo anti-CD20 apresentou variações de pureza radioquímica quando sua estabilidade foi testada em cinco condições estabilizadoras diferentes. Entretanto, a condição em que ácido gentísico foi combinado com congelamento demonstrou-se apropriada e capaz de minimizar os efeitos de autoradiólise do anticorpo marcado com alta atividade terapêutica de iodo-131. O anticorpo marcado apresentou imunoreatividade abaixo da relatada na literatura. A distribuição biológica em camundongos Swiss sadios revelou captação elevada no pulmão, fígado, e intestino delgado. O clareamento sanguíneo do anticorpo marcado foi relativamente rápido. Contudo, dados experimentais revelaram que anticorpos monoclonais anti-CD20 podem ser seguramente marcados com alta atividade de iodo-131 usando o método de Cloramina-T. O uso de cromatografia em camada delgada (ITLC-SG) na avaliação de pureza radioquímica mostrou-se apropriado, eficiente, prático, além de simples e rápido. O método de purificação utilizado demonstrou-se eficiente para a separação do anticorpo marcado do iodo livre. A abordagem inédita apresentada neste estudo, no sentido de viabilizar transporte e comercialização do produto marcado, referiu-se ao estudo de estabilidade do Acm marcado. A distribuição biológica do anticorpo demonstrou-se compatível com a distribuição do anticorpo íntegro indicando ótima estabilidade relativa in vivo. Os resultados deste estudo confirmam a potencialidade do anticorpo para a radioimunoterapia de linfomas do tipo não-Hodgkin. / Lymphomas are malignancies of the lymphatic system, described by Thomas Hodgkin in 1932. Traditionally, lymphomas are classified in two basic groups: Hodgkin disease and non-Hodgkin lymphoma (NHL). Patients with NHL were earlier treated with radiotherapy alone or in combination with immunotherapy using monoclonal antibody anti-CD20 (ex., Rituximab-Mabthera, Roche). However, Radioimmunotherapy is a new modality of treatment for patients with NHL, in which cytotoxic radiation from therapeutic radioisotopes is delivered to tumors through monoclonal antibodies. This study focused on labeling conditions of monoclonal antibody anti-CD20 (Rituximab-Mabthera, Roche) with iodine-131, by direct radioiodination method using Chloramine-T as oxidizing agent. Labeling parameters investigated were: Radiochemical purity (RP), method of purification, incubation time, antibody mass, oxidative agent mass, stability in vitro, stability in vivo, immunoreactivity and biological distribution performed in normal Swiss mouse. Product of high radiochemical purity was obtained with no notable difference between the methods applied. No clear evidence of direct influence of incubation time on radiochemical purity of the labeled antibody was observed. Whereas, a clear evidence of direct influence of activity on radiochemical purity of the labeled antibody was observed when antibody mass was varied. After purification, the labeled product presented radiochemical purity of approximately 100 %. Product of superior radiochemical yield was observed when standard condition of labeling was used. The labeled product presented variation in radiochemical purity using five different stabilizer conditions. The condition in which gentisic acid was combined with freeze appears more suitable and capable of minimizing autoradiolysis of the antibody labeled with high therapeutic activity of iodine-131. The labeled product presented low immunoreactivity when compared to the literature. Biological distribution in normal Swiss mouse demonstrated high uptake of the labeled antibody in lungs, liver, and small intestine. The progressive loss of activity in blood indicates fast blood clearance of the labeled antibody that is eliminated through the kidney, in urine. The experimental data proved that mAb anti-CD20 can be securely labeled with high therapeutic activity of iodine-131 using Chloramine-T method. Radiochemical purity determined by chromatographic plates (ITLC-SG) proved to be appropriate, efficient, practical and simple. The purification method demonstrated to be appropriate and efficient for separating the labeled antibody from free iodine. The results of stability of the labeled antibody presented in this study suggest that the product can be transported and commercialized using the condition in which gentisic acid was combined with freeze. In vivo distribution of the labeled antibody shows to be compatible with integral antibody distribution, indicating good in vivo stability. Results obtained in this study confirmed the potential of the labeled product anti-CD20-131I for radioimmunotherapy of non-Hodgkin lymphoma (NHL).

Na primeira parte desta tese são apresentados os resultados referentes ao desenvolvimento de uma metodologia de &#945;-alquinilação eletrofílica de aldeídos com o reagente de iodo hipervalente TMS-EBX, empregando NaHMDS como base e TBAF. Aldeídos acíclicos foram submetidos a esta transformação e 9 exemplos de álcoois homopropargílicos foram obtidos em rendimentos de 50-81%, após uma etapa de redução com NaBH4. A transformação desenvolvida revelou-se aplicável também com o reagente de iodo hipervalente Ph-EBX e 2 exemplos foram obtidos em 24 e 40% de rendimento. O álcool homopropargílico precursor de um inibidor da bactéria que produz a toxina botulínica foi preparado em uma escala de 5 mmol sem a necessidade de alterar as condições reacionais já otimizadas. Na segunda parte desta tese são apresentados os resultados referentes ao desenvolvimento de uma metodologia para a síntese de cetonas cíclicas e 2-cromanonas &#945;-alquinil-&#946;-substituídas por meio de uma sequência de adição 1,4/alquinilação eletrofílica empregando cumarinas e enonas como material de partida, utilizando o reagente de iodo hipervalente TMS-EBX. Os enolatos foram gerados com sucesso a partir de uma reação de adição 1,4 catalisada por cobre utilizando complexos de alumínio e reagentes de Grignard como fontes nucleofílicas. No total foram obtidos 17 exemplos em 34-89% de rendimento e em alta diastereosseletividade. Realizamos três modificações estruturais visando aumentar a complexidade estrutural dos produtos sintetizados. A reação Click, rea- ção de Sonogashira e redução mediada por NaBH4 foram aplicadas com sucesso. Por fim, na terceira parte desta tese são apresentados os resultados preliminares referentes ao desenvolvimento de uma metodologia de síntese de furanos a partir da acetofenona e do reagente de iodo hipervalente Ph-EBX, empregando NaHMDS comoviii base. A acetofenona foi submetida a esta transformação e uma mistura de furanos di- e trissubstituídos foram obtidos em 49% de rendimento. Um experimento controle demonstrou que a alquinilação do ânion terc-butóxido, em uma reação extremamente rápida, é a principal via de consumo do Ph-EBX e o composto (terc-butoxietinil)benzeno foi obtido em 92% de rendimento. Esta reação lateral é a principal responsável pelo baixo rendimento da reação de síntese dos furanos. / In the first part of this work are presented the results relative to the development of a methodology of &#945;-electrophilic alkynylation of aldehydes with the hypervalent iodine reagent TMS-EBX, employing NaHMDS as base and TBAF. Acyclic aldehydes were submitted to this transformation and 9 examples of homopropargylic alcohols were obtained in 50-81% yield, after a reduction step with NaBH4. The developed transformation proved to be works also with the hypervalent iodine reagent Ph-EBX and 2 examples were obtained in 24 and 40% yield. The homopropargylic alcohol precursor of an inhibitor of bacteria that produces a botulinic toxin was prepared at a 5 mmol scale without change the reaction condition already optimized. In the second part of the thesis are presented the results relative to the development of a methodology for the synthesis of cyclic ketones and 2-chromanones &#945;-alkynyl-&#946;-substituted by the1,4-addition/electrophilic alkynylation sequence using coumarins and enones as a starting material and the hypervalent iodine reagent TMS-EBX. The enolates were generated with success from a Cu-catalyzed 1,4 addition using aluminum complexes and Grignard reagents as nucleophilic source. In total 17 examples were obtained in 34-89% yield and high diastereoselectivity. We carried out three structural modification aiming to increase the complexity of the products synthesized. Click reaction, Sonogashira reaction and reduction promoted by NaBH4 were applied with success. Finally, in the third part of the thesis are presented the preliminary results relative to the development of a methodology for synthesis of furans from acetophenone and the hypervalent iodine reagent Ph-EBX, using NaHMDS as a base. Acetophenone was submitted to this transformation and only one example was obtained in 49% yield in a mixture of di- and trisubstituted furans. A control experimentx showed that the alkynylation of tert-butoxide anion, in an extremely fast reaction, is the main path of consumption of the Ph-EBX reagent and the compound (tert-butoxyethynyl)benzene was obtained in 92% yield. This side reaction is the main responsible for the low yield of the reaction of synthesis of furans.

As infecções adquiridas durante cirurgias oftalmológicas podem ter efeitos devastadores. O objetivo do presente estudo foi de comparar a proporção de culturas bacterianas negativas no fundo de saco conjuntival inferior após uma ou três gotas sequenciais de iodopovidona a 5% (PVPI). Os voluntários foram aleatoriamente designados para receber uma gota de PVPI (grupo PVPI) (no tempo 28 minutos) ou três gotas de PVPI (grupo PVPI+) (nos tempos 0, 20 e 28 minutos) no saco conjuntival inferior em olhos selecionados aleatoriamente. Um cotonete conjuntival foi identicamente obtido cinco minutos antes e 30 minutos após o tempo 0. A espessura corneana central foi medida da mesma maneira antes do tempo 0 e após o tempo 30 minutos. Os esfregaços conjuntivais foram incubados aerobicamente em meio líquido de tioglicolato enriquecido (caldo de carne) e em três meios de cultura sólidos (ágar chocolate, ágar de tripticase-soja com 5% de sangue de ovelha e ágar Sabouraud). No grupo PVPI (n=59), a proporção de olhos com culturas bacterianas negativas após o uso do PVPI (79,7%) não diferiu significativamente do valor basal (76,3%; p=0,7539). No grupo PVPI+ (n=61), a proporção de olhos com culturas bacterianas negativas após instilação de PVPI (85,3%) foi significativamente maior do que antes da intervenção (70,5%) (p=0,0177). No entanto, a análise estatística intergrupos não detectou esta diferença. Não houve diferença significativa na média da espessura corneana central antes e após a intervenção em ambos os grupos. A instilação de três gotas sequenciais de PVPI foi associada ao aumento na proporção de olhos com culturas conjuntivais negativas, enquanto que a instilação de uma única gota de PVPI não demonstrou este aumento. É necessário um estudo mais aprofundado para determinar se a diferença entre os regimes de administração da PVPI está associada a diferentes taxas de infecções oculares pós-operatórias. / Infections acquired during ophthalmic surgery can be devastating. The purpose of the current study is to compare the proportion of negative bacterial cultures after one versus three sequential drops of povidone-iodine (PI) 5% into the inferior conjunctival fornix. Patients were randomly assigned to receive 1 (PI group) drop (at time 28 minutes) or three (PI plus group) sequential drops (at time 0, 20 and 28 minutes) of PI 5% into the inferior conjunctival sac of one randomly selected eye. A conjunctival swab was identically obtained 5 minutes before and 30 minutes after time 0. Central corneal thickness (CCT) was measured in the same way before time 0 and after time 30. Conjunctival swabs were incubated aerobically in enriched Thioglycolate liquid medium (meat broth) and in three solid culture media (chocolate agar, trypticase soy agar with 5% sheep blood, and Sabouraud agar). In the PI group (n=59), the proportion of eyes with negative bacterial cultures after PI (79.7%) did not differ significantly from baseline (76.3%; p=0.7539). In the PI plus group (n=61), the proportion of eyes with negative bacterial cultures after PI (85.3%) was significantly higher than before PI (70.5%) (p=0.0177). However, the intergroup statistical analysis did not detect this difference.There was no significant difference in mean CCT before and after the intervention in both groups. Instillation of three sequential drops of PI was associated with an increase in the proportion of eyes with negative conjunctival cultures, while instillation of a single drop of PI did not demonstrate this increase.Further study is warranted to determine whether the difference between the PI administration regimens is also associated with differences in the rates of postoperative ocular infections.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho é apresentada uma metodologia para a caracterização dosimétrica de fontes seladas de braquiterapia de 125I. Realizar a caracterização dosimétrica de uma fonte é uma atribuição tanto de quem produz tais fontes como do usuário. O fabricante precisa fornecer ao usuário clínicas, hospitais e laboratórios secundários um certificado de calibração contendo tal caracterização. O usuário por sua vez, precisa confirmar tais valores com testes específicos antes de fazer uso das fontes em pacientes ou em pesquisa. A intensidade de kerma no ar das fontes de 125I emissoras gama, da OncoSeed, modelo 6711, utilizadas neste trabalho, foi medida por meio de um conjunto dosimétrico constituído por uma câmara tipo poço, modelo HDR Plus 1000, da Standard Imaging e um eletrômetro modelo Max 4001 do mesmo fabricante. Este conjunto dosimétrico foi submetido a um comissionamento, ou seja, foram realizados testes de correntes de fuga, testes de reprodutibilidade e de repetitividade, testes de determinação da posição de máxima resposta da câmara poço e teste de linearidade. Após estes procedimentos foi realizada a calibração cruzada do conjunto dosimétrico e então, o teste de exatidão. Uma vez realizado o comissionamento do conjunto dosimétrico, foi realizada a dosimetria de fontes de 125I, da OncoSeed, modelo 6711. As curvas de isodoses foram adquiridas por meio de estudos e análises em filmes radiocrômicos e filmes dosimétricos, irradiados com as mesmas fontes utilizadas na dosimetria com o conjunto dosimétrico. É apresentada também uma metodologia para avaliação de incertezas das medições de tais fontes. / This work presents a methodology for the dosimetric characterization of 125I brachytherapy sealed sources. Since the dosimetric characterization of a source is an attribution of both the manufacturer and the user, a calibration certificate needs to be provided by the manufacturer to the user - clinical, hospitals and secondary laboratories. It is an obligation of the user to check the values with specific tests before using the referred sources in patients or research. The air kerma strength for 125I sources model 6711 manufactured by OncoSeed were experimentally verified by means of a dosimetric set-up composed by a well chamber model HDR Plus 1000, manufactured by Standard Imaging and an electrometer model Max 4001 of the same manufacturer. The set-up was commissioned by means of current leakage tests, reproducibility and repetitively tests, positioning tests and linearity. At last, a crossed calibration of the dosimetric set up and the exactness test. On the next stage, isodoses curves were determined by means of measurements in radiochromic and dosimetric films. A methodology to evaluate the uncertainties of the measurements of the referred sources is also presented.