Made available in DSpace on 2014-06-11T19:32:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2001Bitstream added on 2014-06-13T19:42:37Z : No. of bitstreams: 1 hokama_nk_dr_botfm.pdf: 442709 bytes, checksum: 19c729c7bb99de9b488b0c496f8b3922 (MD5) / A hemoglobina, o componente principal do citoplasma eritrocitário, está sujeita à oxidação, fisiologicamente ou por agentes externos, seja através da formação de Metahemoglobina, ou pela oxidação da cisteína β93 por agentes tiois. Impossibilitado de sintetizar proteína, o eritrócito depende primordialmente da via glicolítica, que, além de fornecer ATP, através da integração da formação de NADH e da Via da Hexose Monofosfato, mantém o potencial redutor extremamente eficiente. A presente investigação teve como finalidade avaliar o sistema de óxido-redução eritrocitário, à partir da oxidação da hemoglobina pelas seguintes drogas: a) Nitrito de Sódio, indutora da formação de Metahemoglobina; b) Azul de Metileno, utilizado terapeuticamente e em testes laboratoriais na redução de Metahemoglobina; c) Cistamina, agente tiol, que induz à formação do complexo Hemoglobina-Etilamina, através da oxidação da cisteína β93. Doadores de sangue da Divisão Hemocentro foram convidados a participar do trabalho e tiverem seu sangue coletado após consentimento - 96 - verbal e por escrito. Todos os indivíduos eram do sexo masculino, não anêmicos e sem deficiência de G6PD. Foram utilizados, para os testes, glóbulos lavados, ressuspensos em PBS, pH 7.45, com hemoglobina ajustada entre 11 e 13 g/dl, na presença de glicose e incubados a 37o C com as drogas testadas, nos momentos 10. 90 e 180 minutos de incubação... / Hemoglobin, the essential component of erythrocyte cytoplasm, is physiologically prone to oxidation by external agents, through the formation of Methemoglobin or the oxidation of β93 cysteine by thiol agents. Unable to protein synthesis, the erythrocyte depends essentially on glycolysis, which, besides producing ATP, maintains the highly efficient reduction potential through the integration of NADH production and the Hexose Monophosphate Shunt. The present investigation’s purpose was to evaluate the erythrocyte antioxidant system by studying hemoglobin oxidation by the following substances: a) Sodium Nitrite (SN), a well known Methemoglobin-forming agent; b) Methylene Blue (MB), a Methemoglobin reductant reagent, available for therapeutic and laboratory tests; c) the thiol reagent Cystamine (CI), that reacts with hemoglobin through the β93 cysteine oxidation, forming the Hemoglobin-Ethylamine complex. After informed... (Complete abstract click electronic access below)

Orientador: Luiz Shiguero Matsubara / Resumo: A hemoglobina, o componente principal do citoplasma eritrocitário, está sujeita à oxidação, fisiologicamente ou por agentes externos, seja através da formação de Metahemoglobina, ou pela oxidação da cisteína β93 por agentes tiois. Impossibilitado de sintetizar proteína, o eritrócito depende primordialmente da via glicolítica, que, além de fornecer ATP, através da integração da formação de NADH e da Via da Hexose Monofosfato, mantém o potencial redutor extremamente eficiente. A presente investigação teve como finalidade avaliar o sistema de óxido-redução eritrocitário, à partir da oxidação da hemoglobina pelas seguintes drogas: a) Nitrito de Sódio, indutora da formação de Metahemoglobina; b) Azul de Metileno, utilizado terapeuticamente e em testes laboratoriais na redução de Metahemoglobina; c) Cistamina, agente tiol, que induz à formação do complexo Hemoglobina-Etilamina, através da oxidação da cisteína β93. Doadores de sangue da Divisão Hemocentro foram convidados a participar do trabalho e tiverem seu sangue coletado após consentimento - 96 - verbal e por escrito. Todos os indivíduos eram do sexo masculino, não anêmicos e sem deficiência de G6PD. Foram utilizados, para os testes, glóbulos lavados, ressuspensos em PBS, pH 7.45, com hemoglobina ajustada entre 11 e 13 g/dl, na presença de glicose e incubados a 37o C com as drogas testadas, nos momentos 10. 90 e 180 minutos de incubação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hemoglobin, the essential component of erythrocyte cytoplasm, is physiologically prone to oxidation by external agents, through the formation of Methemoglobin or the oxidation of β93 cysteine by thiol agents. Unable to protein synthesis, the erythrocyte depends essentially on glycolysis, which, besides producing ATP, maintains the highly efficient reduction potential through the integration of NADH production and the Hexose Monophosphate Shunt. The present investigation's purpose was to evaluate the erythrocyte antioxidant system by studying hemoglobin oxidation by the following substances: a) Sodium Nitrite (SN), a well known Methemoglobin-forming agent; b) Methylene Blue (MB), a Methemoglobin reductant reagent, available for therapeutic and laboratory tests; c) the thiol reagent Cystamine (CI), that reacts with hemoglobin through the β93 cysteine oxidation, forming the Hemoglobin-Ethylamine complex. After informed... (Complete abstract click electronic access below) / Doutor

The current practice of red blood cell banking for transfusion medicine relies primarily on a six-week liquid storage. A growing demand for red blood cell (RBC) products has prompted the search for alternative preservation methods including dry storage. Being desiccation sensitive, attempts to recover RBCs from the dry state have failed. This dissertation offers a new mechanistic understanding of desiccation-induced cellular injury that is correlated with the oxidative state of the hemoglobin. The general hypothesis states that RBC desiccation is accompanied with non-physiological oxidation of hemoglobin and, consequently, the release of toxic products capable of compromising cellular recovery through oxidative injury. Data acquired for this dissertation demonstrates that water loss induces a drastic increase in the rate of hemoglobin oxidation, formation of intracellular reactive oxygen species (ROS), and hemolysis. Pharmacological treatments of the hemoglobins oxygen binding site reveal that hemoglobin-induced cellular injury is more prominent in RBC samples that are partially dehydrated (about 3.5 to 5.5 g H2O/g dry weight) than in samples that are relatively dry ( 2 g H2O/g dry weight). Furthermore, partially dehydrated RBC samples contain higher levels of oxidized lipids than more fully dried samples. This dissertation also examined the role that glucose and glutathione play in enhancing desiccation tolerance of RBCs. Glucose treatment (5 mmol/L) significantly reduced ROS formation and hemolysis levels in partially dehydrated RBC samples (5.8 0.3 g H2O/g dry weight), but not in samples that are relatively dry (2.8 0.5 g H2O/g dry weight). Treating RBCs with DL-buthionine-(S,R)-sulfoximine, a glutathione depleting agent, was correlated with reduced levels of desiccation-induced hemolysis. This study suggests that desiccation-induced oxidative injury in RBCs is water dependent corresponding to earlier stages of water loss, in which cells can retain metabolic activity. Pharmacological treatments at this stage can significantly affect cell recovery as demonstrated with modifying the hemoglobins oxygen binding site, glutathione depletion, and glucose supplementation. On the other hand, increased cytoplasmatic viscosity compromises biochemical reactions at lower residual moisture contents, and cellular injury is likely the result of physical and mechanical stress. These differences should be taken into consideration in the design of innovative approaches to RBC preservation.

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