A via de amplificação da secreção de insulina estimulada por glicose (GSIS) é um fenômeno discutido na literatura, cujos componentes são amplamente debatidos. Evidências sugerem que a condutância a Cl- compõe parte desta via. Porém, o mecanismo pelo qual essa condutância desempenharia papel na via de amplificação ainda é debatido, e, além disso, as ferramentas farmacológicas para estudo dessas afeta o transporte de outros ânions, como bicarbonato (HCO3-). Buscamos neste trabalho compreender a contribuição do transporte desses ânions para a via de amplificação da GSIS levando em consideração a distribuição de Cl- e HCO3- extracelular em células INS-1E. Concluímos que o transporte de ânions nas células INS-1E não contribui para a via de amplificação da GSIS, porém essas células não expressaram os canais CFTR e Anoctamina 1 que foram relacionados com esse fenômeno. Acreditamos que em células secretoras de insulina que expressem esses canais, o transporte de ânions possua alguma relevância funcional. / The amplification pathway of glucose stimulated insulin secretion (GSIS) is a phenomenon discussed in the literature, which components are broadly debated. Evidence suggests that Cl- conductance composes part of this pathway. However, the mechanism that this conductance would play role on the amplification pathway still is debated, and, besides that, the pharmacological tools to study these affects transport of other anions, such as bicarbonate (HCO3-). We aimed in this study to understand the contribuition of anion transport for the amplification of GSIS considering the Cl- and HCO3- extracellular distribuition in INS-1E cells. We concluded that anion transport in INS-1E cell line do not contribute for the amplification pathway of GSIS, however those cells do not express CFTR and Anoctamin 1 channels which were related with this phenomenon. We believe that in insulin secretin cells that express those channels, the anion transport may have a functional relevance.

Expanded bed chromatography using ion-exchange media is a powerful first step in purification processes. Expanded bed chromatography can be used to extract components from complex and viscous solution. This can be achieved because of the void created between adsorbent particles where as in packed bed chromatography, the adsorbent is too compact and dense for a complex feed stock to flow through. Expanded bed chromatography was used to purify bovine serum albumin (BSA) from chicken egg white (CEW). The high viscosity of CEW presents a unique challenge for efficient large-scale protein purification. This project aimed to optimize and evaluate a separation method that is believed to be particularly suitable for high viscosity solutions: expanded-bed ion exchange chromatography. The BSA was admixed into the CEW and the solution was pumped through the column for purification. The media used in the column was Streamline DEAE which is an anion-exchanger. The yield obtained was 85% and the purity was 57%. A mathematical model to understand and predict the behavior of expanded bed chromatography was developed to provide an estimation of the breakthrough curves obtained for BSA. A small sized porous dense adsorbent was also synthesized to enhance the purification process. This zirconia-based adsorbent allows use of higher flow velocities that is a key factor when working with viscous fluids such as chicken egg white.

Hybrid trap experiments are set-ups that allow to study the interaction between ions and atoms in cold controlled environment. In such context, molecular anions present specific theoretical and experimental interests and challenges. In this work, we have used extensive \textit{ab initio} methods to investigate several collisional anionic systems: (1) M + OH$^{-}$ (where M are alkali or alkaline earth atoms), (2) Rb and H + OH(H$_{2}$O)$_{n}^{-}$ (with $n=0,1,2,3,4$) and (3) Rb and Li + C$_{2}^{-}$. Several molecular properties such as vertical detachment energies or electroaffinities, optimized structures, harmonic frequencies, potential energy curves or surfaces, etc have been calculated using high level quantum chemistry approaches. The results have been used to make predictions on the related reactivity in low energy regime. We emphasis on electronic detachment processes by carefully analysing the difference between the neutral and anionic potential energy surface. The Rb + OH$^{-}$ system is currently under experimental investigation. Therefore, a detailed study of its reactivity is carried out in the present work. We have analysed the different reactive channels arising from both collision involving the ground state and first electronic excited state of Rb. Using our calculated potentials and a capture model based dynamics, we have extracted cross sections and rate constants. Comparison with other alkali and earth alkaline atoms are made. Hydrated hydroxide cluster anions are planned by the experimental group as upcoming studied systems. We present here our preliminary results on the possible outcome when considering collisions with Rb and we discuss their implications for hybrid trap experiments. We make comparison with H as a colliding partner and consider our results in the context of astrochemistry. Finally we propose the C$_{2}^{-}$ molecular anion as an alternative to OH$^{-}$. Its interaction and reactivity with Rb and Li are investigated and the results are used to motivate our suggestion. Furthermore, for the Rb+OH$^{-}$ and Rb+C$_{2}^{-}$ system, we have also investigated the effect of a non-thermal collision energy distribution on the rate constants. At last, in light of the discussions related to each topic, general conclusions on the use of molecular anions in hybrid trap experiments are drawn. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Foram utilizadas 8 vacas Holandesas em lactação, distribuídas em um quadrado latino (4x4), replicado, conduzidos durante o verão, por um período de 72 dias. O objetivo desse trabalho foi estudar quatro níveis de dietas catiônicas, sobre a IMS, produção, composição e propriedades físico-químicas do leite, pH urinário, temperatura corporal e parâmetros ácido-base do sangue, em vacas após o pico de lactação. Para a manipulação do BCAD, foram adicionadas diferentes concentrações de bicarbonato de sódio nas dietas, obtendo-se os seguintes tratamentos: +150, +250, +400 e +500mEq/kg MS. A temperatura corporal das vacas não foi afetada pelo balanço cátion-aniônico da dieta. O bicarbonato, o pH, o CO2 total e a pCO2 do sangue aumentaram linearmente com o aumento do BCAD. A concentração de cálcio no sangue apresentou resposta quadrática, com maior valor para o menor BCAD. As concentrações de sódio e potássio do sangue não foram modificadas significativamente pelo BCAD e a concentração de cloro diminuiu linearmente com o aumento do BCAD. O aumento do BCAD resultou em aumento da ingestão de matéria seca e produção de leite. Não houve diferença significativa para as variáveis: porcentagem de gordura, densidade e índice crioscópico, do leite. O pH do leite aumentou linearmente e a acidez apresentou resposta cúbica, com o aumento do BCAD. Conclui-se que a manipulação do BCAD afeta o equilíbrio ácido-base das vacas, mesmo dentro de variação positiva. Devido ao aumento da IMS e da produção de leite, verificou-se efeito benéfico do uso de dietas catiônicas, para vacas após o pico de lactação. / Eight lactating Holsteins cows were distributed in 4 x 4 replicated Latin square, during the summer, for a period of 72 days. The objective of this research was to study the effect of four cationic diets levels, on the dry matter intake, milk production, composition, and physico-chemical parameters, urinary pH, body temperature and blood acid-base parameters, in cows, after the lactation peak. For DCAB manipulation were added different concentrations of sodium bicarbonate in the diets and the following treatments were obtainned: +150, +250, +400 e +500mEq/kg DM. The cows body temperature was not affected by dietary cation-anion balance. Blood bicarbonate, pH, total CO2 and pCO2 increased linearly with the increase of dietary CAB. Calcium concentration in the blood decreased quadratically with dietary CAB increased. Sodium and potassium concentration in the blood were not modified significantly with the DCAB and concentration of chloride decreased linearly with increase of DCAB. Increasing BCAD resulted in higher DM intake and milk yield. The diets did not affect milk fat percentage, density and crioscopic index. Milk pH increased linearly and acidity decreased cubically with the increase of dietary CAB. It was concluded that DCAB manipulation affected the acid-base status of cows, even inside of positive variation. Due to the increase of DM intake and milk yield, it was verified a beneficial effect of the cationic diets for cows after the lactation peak.

Faculty of Science School of Pathology(Molecular Medicine and Haematology). 9707563v tridium@acenet.co.za / The erythrocyte carries gases between the cells and the lungs, and has to distort to negotiate narrow splenic sinuses and capillaries. This distortion necessitates a high surface area to volume ratio that is maintained by the erythrocyte membrane skeleton, a network of proteins including spectrin and protein 4.1. The skeleton anchors the lipid bilayer through attachment to integral membrane proteins, notably the anion exchange protein, band 3. Abnormalities of the erythrocyte membrane proteins cause loss of cell elasticity and ultimately the erythrocytes become prematurely trapped in the spleen where they are phagocytosed, resulting in haemolytic anaemia. Three mutations causing band 3-deficient hereditary spherocytosis (HS), a haemolytic anaemia characterised by spherical erythrocytes, were located using restriction enzyme analysis and DNA sequencing. Proband A (Black) is heterozygous for band 3 Pinhal (R490H) and has mild clinical symptoms. Proband B and his mother (Caucasian) are heterozygous for band 3 Bicetre (R490C) and have severe anaemia requiring transfusions and splenectomy, respectively. These results confirm codon 490 as a hotspot for mutations and indicate the effect of different amino acid substitutions in the same position on clinical severity. Proband C (Black) is homozygous for a novel mutation (E508K) for which her parents are heterozygous. The proband is severely affected and transfusion- dependent whereas her father has moderate anaemia and her mother is asymptomatic. It is speculated that a secondary factor modulates their clinical symptoms. All of these mutations occur in a CpG dinucleotide, a common source of DNA mutations, and are located within the highly conserved exon 13, which encodes the third to fifth α-helices and the second extracellular loop of the transmembrane region of band 3. The mutations are likely to alter the conformation of band 3, impairing its insertion into the erythrocyte membrane. No causative mutations were located in another 12 band 3-deficient HS kindred using restriction enzymes and single strand conformation polymorphism analysis. Ten protein 4.1-deficient patients with hereditary elliptocytosis, a haemolytic anaemia characterised by elliptical erythrocytes, were also studied. Immunoblot analyses ruled out abnormally sized protein 4.1 and three known DNA mutations were excluded using restriction enzyme analysis. Further studies are required to elucidate the cause of the haemolytic anaemia in these kindred. This study advanced our knowledge of the molecular basis of HS in South African kindred and highlighted the susceptibility of CpG dinucleotides to mutations.

The carbonate radical anion (CO3•-, CR) is an important reactive oxygen species produced in vivo by one-electron oxidation of CO2 or bicarbonate, constituents of the major physiological buffer. It was demonstrated for the first time by using an HPLC-based analysis of low-molecular products of DNA damage that CRs react with DNA 2΄-deoxyribose by the hydrogen abstraction mechanism. CRs exhibit a ~ 800-fold preference for one-electron oxidation of guanine over hydrogen abstraction from DNA sugar, in sharp contrast with •OH. CRs also have, as compared to •OH, an increased preference for the H1΄ abstraction, which is the most thermodynamically favorable due to the highest stability of the respective deoxyribosyl radical but kinetically the slowest due to low solvent accessibility, by the expense of the decreased preference for the H5΄ abstraction. All these findings are in agreement with the characteristics of CR as a potent oxidant and selective hydrogen abstractor.

Development of an in vitro model for the early stages of cardiovascular disease is a current necessity. Cardiovascular disease is the leading cause of death in the United States and throughout the world. Oxidative stress and reactive oxygen species have been implicated in cardiovascular disease development. An in vitro model of these processes will improve our understanding of cardiovascular disease development and allow for the development of additional treatments. Atherosclerosis is an inflammatory disease and increased levels of H2O2 are associated with inflammation. The model focuses on H2O2-induced oxidative stress under static and shear conditions. Previous studies have documented increased O2.- and increased cytotoxicity in smooth muscle cells exposed to H2O2. Under static culture, endothelial cells exposed to H2O2, exhibited increased O2.- over basal levels via NOS and NAPDH oxidase pathways. Increased O2.- was attenuated by MnSOD adenoviral-mediated upregulation and endothelial cell exposure to Tiron. This suggests NOS and NADPH oxidase as sources of increased O2.- under H2O2-induced oxidative stress. Endothelial cell cytotoxicity was increased with H2O2 exposure. The increase in cytotoxicity was diminished upon exposure to Tiron or L-NAME. Under shear conditions (8.2 dynes/cm2), endothelial cells exposed to H2O2 exhibited increased O2.- compared to control via an L-NAME (specific inhibitor NOS) and Apocynin (NADPH oxidase inhibitor) inhibitable mechanism. This suggests NOS and NADPH oxidase as sources of increased O2.- under H2O2-induced oxidative stress. The increased O2.- was attenuated with MnSOD adenoviral-mediated upregulation and endothelial cell exposure to Tiron (an O2.-scavenger). Endothelial cell attachment under shear with exposure to H2O2 was improved with MnSOD adenoviral-mediated upregulation as observed by decreased loss of the endothelial cell monolayer compared with H2O2 exposed endothelial cells. Endothelial cells exposed to H2O2 exhibit increased O2.-, suggesting that H2O2-induced oxidative stress may be a reasonable model for atherosclerosis. NOS and NADPH oxidase co-inhibition under shear and static culture demonstrated that NOS and NADPH oxidase inhibition is non-additive under static culture, yet additive under shear. Co-inhibition results suggest a complex relationship between the two enzymes that requires additional experimentation to deconvolve.

No description available.

Exchange reactions of anions, especially ferrocyanide and carbonate, with layered double hydroxides (LDHs) were investigated in relation to the origin of life on the early Earth. The effect on ferrocyanide exchange of concentration, pH, reaction time and cations are discussed. It was found that there were two different kinds of ferrocyanide species: one was that intercalated into the layered structure, occupying a site of D symmetry within the LDHs, while in the other, the ferrocyanide group retains full O symmetry. In addition, very low concentration, ferrocyanide associated with LDH will change its FTIR absorption shape. Carbonate was much more strongly intercalated than ferrocyanide into the LDHs, probably because of the strong hydrogen bonding.

Deux thématiques principales ont été étudiées au cours de cette thèse. La première partie porte sur la synthèse de complexes de manganèse dérivés de porphyrines et de salens. L'activité catalytique de ces complexes a été évaluée dans l'époxydation d'alcènes non-Fonctionnalisés. Suite à cette étude, les propriétés électroniques des ligands ont été étudiées, notamment par le biais de la complexation d'anions. Dans une deuxième étape, nous nous sommes intéressés à la synthèse de phosphines P-Chirogéniques. Afin de trouver un substitut à l'éphédrine, couramment utilisée dans ces synthèses, des dérivés du (1S,2S)-2-Aminocyclohexanol et de la D-Glucosamine ont été synthétisés. L'utilisation de groupements sulfonamides a permis l'obtention aisée d'oxazaphospholidines N-Tosylées. L'un ou l'autre diastéréoisomère de cet hétérocycle peut être obtenu en fonction du degré d'oxydation du réactif phosphoré utilisé. Avec cette stratégie, divers oxydes de phosphines ont été obtenus avec de bons rendements et de bonnes énantiosélectivités / This thesis is divided in two parts. The first part focuses on the synthesis of manganese complexes derived from porphyrins and salens. The catalytic activity of these complexes were evaluated toward the epoxidation of unfunctionalized alkenes. Next, the electronic properties of the ligands were evaluated using their anion binding properties. In a second part, we were interested in the synthesis of P-Chirogenic phosphines. In order to find a surrogate to ephedrine, that is commonly used in those syntheses, derivatives from (1S,2S)-2-Aminocyclohexanol and D-Glucosamine were synthesized. The use of sulfonamides allows the access to N-Tosylated oxazaphospholidines. Both diastereoisomers could be synthesized depending on the oxydation state of the phosphine precursor. Using this strategy, various phosphine oxides were obtained in good yields and enantioselectivities