The genetic disorder sickle cell anemia causes hemolytic anemia and sickle pain crisis, episodes of microvascular occlusion resulting in painful ischemic tissue damage. Pain crisis is thought to occur when sickle erythrocytes adhere in the post-capillary venule, partially occluding the vessel. The resulting slowed blood flow causes more extensive cell adherence and entrapment of rigid, deoxygenated erythrocytes until the vessel is entirely occluded. It was hypothesized that the inflammatory mediators histamine and tumor necrosis factor-, factors known to cause endothelial expression of adhesive ligands, might significantly increase sickle erythrocyte adhesion, and thus be capable of initiating sickle pain crisis. It was also hypothesized that the perfusion shear stress environment of the endothelium, known to be oscillatory and reduced in sickle cell patients, was a significant mediating factor of sickle cell adhesion. An in-vitro flow chamber using cultured endothelial cells and erythrocytes from blood samples of sickle cell anemic patients was used to quantify sickle erythrocyte adherence to stimulated and unstimulated endothelial cells under shear stresses from 1.0 to 0.1 dyne/cm2. Results showed that both endothelial stimulation and reduction of the perfusion shear stress increased sickle erythrocyte adherence. In combination, the use of inflammatory stimulation with reduced shear stress resulted in further increased adhesion, but only when above the range of 0.1 V 0.2 or 0.4 dyne/cm2, depending on the inflammatory mediator. Adhesion below this level of shear is not significantly increased by endothelial stimulation. The mechanism by which histamine mediates adhesion was investigated, and found to involve the endothelial H2 and H4 receptors and expression of the P-selectin ligand. These data suggest that irregular flow, typical of sickle microvasculature, may act in conjunction with the pro-inflammatory state of sickle vasculature and the histaminergic nature of some pain treatments to initiate or propagate sickle vaso-occlusion. Findings concerning histamine, tumor necrosis factor-alpha, and shear stress effects on adherence are discussed in relation to their possible applicability to patient health, future studies are outlined to confirm the relation of in vitro data to in vivo patient condition, and proposals are made for applying these methodologies to other potential mediators of sickle erythrocyte adhesion.

Adhesion of sickle erythrocytes to vascular endothelium may initiate or propagate occlusive events in sickle cell anemia, many of which are accompanied by infection and the associated inflammatory response. Inflammatory markers are also present in sickle patients during asymptomatic periods. Inflammatory cytokines upregulate expression of endothelial adhesion molecules that promote adhesion of sickle erythrocytes. The data in this work demonstrate that after 2 hrs of stimulation with the cytokine TNF- and alpha;, E-selectin, but not VCAM-1 is upregulated on human dermal microvascular endothelial cells. After 6 hrs of TNF- and alpha; stimulation, both VCAM-1 and E-selectin expression are upregulated on MECs, and sickle erythrocytes bind to both receptors. Because strategies to control inflammation-associated adhesion in vivo may need to account for both VCAM-1 and E-selectin mediated events, control of intracellular signaling pathways leading to receptor expression is an attractive strategy for inhibiting adhesion. Cyclic AMP and nitric oxide are two intracellular signaling molecules important to cytokine-induced receptor expression. The data in this work demonstrate that TNF- and alpha; induced VCAM-1 and E-selectin expression on endothelial cells and sickle erythrocyte adhesion are abated by increasing endothelial cyclic AMP concentrations using Forskolin, IBMX, or Bt2cAMP. Conversely, when sickle erythrocytes, rather than endothelial cells, are treated with reagents that increase intracellular cAMP, adhesion to unstimulated endothelial cells is increased in some patients. Treatment of endothelial cells with reagents such as SNP and DETA-NO that increase nitric oxide significantly inhibits VCAM-1, but not E-selectin expression, induced by TNF- and alpha; stimulation and significantly inhibits sickle erythrocyte adhesion. Treatment of sickle erythrocytes directly with these reagents may also inhibit adhesion. Together these data suggest that cAMP- and nitric oxide-dependent signaling are useful therapeutic targets to inhibit cytokine-induced sickle erythrocyte adhesion to endothelium.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.

Sur l’île de La Réunion, la prévalence du diabète de type 2 est 3,5 fois plus élevée que celle de la France hexagonale. Parmi les diverses complications qu’engendre le diabète, les AVC qui en résultent sont responsables d’une forte mortalité faisant des maladies cardiovasculaires un problème de santé publique majeur sur l’île. Les AVC ischémiques proviennent de l’occlusion d’une artère cérébrale par un thrombus généré localement ou qui s’est détaché d’une plaque d’athérothrombose généralement localisée au niveau des bifurcations carotidiennes. Les plaques compliquées sont souvent caractérisées par des hémorragies intraplaques, responsables de l’extravasation des cellules sanguines. Différents marqueurs moléculaires, protéiques et physiques peuvent refléter ces processus et renseigner le médecin sur l’instabilité de la plaque du patient. Il est donc important d’étudier ces marqueurs de risque de rupture de plaques carotidiennes chez les patients diabétiques, afin d’en prévenir les complications et la mortalité associée. L’hémorragie intraplaque, notamment pourvoyeuse d’érythrocytes et de neutrophiles libérant leurs contenus cytoplasmiques, participe activement à la déstabilisation de la plaque d’athérothrombose chez le diabétique. Cette thèse a permis l’étude de l’influence de ces marqueurs à travers une étude clinique et de proposer un nouveau concept de phagocytose des érythrocytes glyqués par les cellules endothéliales in vitro. Ainsi, les résultats préliminaires de l’étude clinique nous permettent de supposer que la clairance des globules rouges des patients diabétiques est altérée, ce qui leurs permettraient de résider sur une période plus longue dans les plaques de ces patients. De cette manière, les globules rouges pourraient y être pris en charge par d’autres types cellulaires comme les cellules endothéliales. Nous avons tout d’abord mis au point un modèle de glycation des érythrocytes in vitro reflétant un diabète mal équilibré. Nous avons ensuite mis en évidence que les globules rouges glyqués pouvaient être phagocytés par les cellules endothéliales humaines, conduisant à une prolifération limitée et à la surexpression de l’HO-1. Ces données suggèrent qu’une ingestion des érythrocytes glyqués par les cellules endothéliales pourrait amplifier la déstabilisation des plaques d’athérothrombose carotidiennes des diabétiques. / Type 2 diabetes prevalence in Reunion Island, a French overseas department, is 3.5 higher than in France mainland. Among the various diseases caused by diabetes, stroke induces high mortality making cardiovascular diseases a major public health problem on the island. Ischemic stroke results from a cerebral artery occlusion by a thrombus that is locally produced or has detached from an atherothrombotic plaque usually located at the carotid bifurcations. Complicated plaques can are often characterized by intraplaque hemorrhages, responsible for blood cell extravasation. Several molecular and physical markers can reflect these processes and inform the physician about the instability of the patient's plaque. It is therefore of major importance to study the markers of carotid plaque rupture in diabetic patients in order to prevent complications and associated mortality. Intraplaque hemorrhage, providing erythrocytes and neutrophils releasing their cytoplasmic contents, plays an active role in destabilizing atherothrombotic plaque in diabetic subjects. The objectives of the present thesis were to study these markers in a clinical study and to suggest a new concept of red blood cell phagocytosis by endothelial cells in vitro. According to the first results of the clinical study, we can suggest that in diabetic patients, the clearance of red blood cells is impaired. This prolonged residence of red blood cells in atherosclerotic plaques from diabetic patients. In this way, red blood cells could be phagocytosed by othercell types such as endothelial cells. In this work, we have also set up an in vitro model of erythrocyte glycation that reflects a clinical situation of poorly controlled diabetes. We have demonstrated that glycated red blood cell phagocytosed by human endothelial cells, leading to their limited proliferation and to HO-1 overexpression. These data suggest an ingestion of glycated erythrocytes by endothelial cells may amplify the destabilization of carotid atherothrombotic plaques in diabetics.

Hebert and Carruthers (1992) showed that the human erythrocyte glucose transporter is an allosteric complex of four GLUT1 proteins whose structure and substrate binding properties are stabilized by reductant-sensitive noncovalent subunit interactions. The GLUT1 tetramer dissociates into dimers upon exposure to reductant but subunits are not associated via disulfide bridges. Each subunit of SDS-denatured tetrameric GLUT1 exposes only two thiols while reduced denatured GLUT1 exposes all six sulfhydryl groups. They hypothesized that glucose transporter oligomeric structure and cooperative catalytic function resulted from noncovalent subunit interactions promoted or stabilized by intramolecular disulfide bridges. These interactions give rise to an antiparallel arrangement of substrate binding sites within the transporter complex. In the present studies, we tested aspects of this model. Specifically, we wanted 1) to understand why the native, noncovalent, homotetrameric GLUT1 complex is sensitive to reductant, 2) to determine whether the tetramer is more catalytically efficient than the dimer in situ, and 3) to test the hypothesis that it is the antiparallel arrangement of substrate binding sites between subunits that provides the transporter with its catalytic advantage. We used biochemical and molecular biological approaches to isolate specific determinants of transporter oligomeric structure and/or transport function in purified isolated transporter preparations, in intact red cells and in CHO cells. We have also examined the hypothesis that net sugar transport in the human erythrocyte is rate limited by reduced cytosolic diffusion of sugars and/or by reversible sugar association with intracellular macromolecules. Our findings support the hypothesis that each subunit of the parental glucose transporter contains a single intramolecular disulfide bridge located between cysteine residues 347 and 421. This disulfide seems to be necessary for GLUT1 tetramerization. Our findings suggest that GLUT1 N-terminal residues 1 through 199 provide contact surfaces for subunit dimerization but are insufficient for subunit tetramerization. Our studies also show that in situ disulfide disruption by cell impermeant reductants results in the loss of cooperative subunit interactions and a 3 to 15-fold reduction in the transport efficiency of the transporter. We further find that in situ GLUT1 is susceptible to exofacial proteolysis. Exofacial trypsin cleavage eliminates cooperativity between subunits but does not affect transporter oligomeric structure or transport activity. Thus catalytic efficiency does not derive directly from cooperative interactions between substrate binding sites on adjacent subunits. We have confirmed that 30MG transport in human erythrocytes is a diffusion limited process. We find that steady-state sugar uptake in red cells and K562 cells measures two processes - sugar translocation and intracellular sugar binding. We propose a model for native GLUT1 structure and function.

Made available in DSpace on 2014-06-11T19:31:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-05Bitstream added on 2014-06-13T19:41:09Z : No. of bitstreams: 1 pereira_wab_dr_jabo.pdf: 854556 bytes, checksum: 9d7af941da3e924cbf09a5ce3f63ef48 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os ovinos possuem tendência a acumular cobre no organismo. Quando a capacidade de armazenagem hepática se esgota, o cobre é liberado para o sangue causando sinais clínicos da intoxicação. Para verificar as alterações presentes na bioquímica sérica, hemograma, morfologia eritrocitária, perfil de proteínas séricas e concentração de cobre sérico, durante as fases pré-hemolítica e hemolítica da intoxicação crônica por cobre, foram utilizados seis ovinos distribuídos aleatoriamente em dois grupos: G-1 (controle) e G-2 (experimentalmente intoxicados). Os três ovinos do G-2, além da dieta diária receberam 3mg de CuSO4. 5H2O/Kg PV, seguido de aumentos semanais de 3mg de CuSO4. 5H2O/ Kg PV na dose diária. Diariamente realizou-se o exame físico dos ovinos de ambos os grupos. Para obtenção do hemograma e dos componentes bioquímicos sanguíneos foram colhidas amostras com antes (M0 – M3), durante (M4) e após (M5 e M6) a crise hemolítica. Foram realizadas necropsias dos ovinos do G-2 que morreram e dos ovinos do G-1, submetidos à eutanásia ao fim do experimento e fragmentos do fígado desses animais foram colhidos para avaliação histopatológica. Durante a fase pré-hemolítica evidenciaram-se poucas alterações, entretanto durante a crise hemolítica os ovinos do G-2 apresentaram anemia macrocítica normocrômica, predomínio de hemácias com morfologia de acantócitos, leucocitose por neutrofilia, elevação nas atividades séricas de AST,GGT, CK e hipercupremia; Os teores séricos de ceruloplasmina apresentaram-se diminuídos e os teores de transferrina, proteína de 35.000 Da e IgG de cadeia leve apresentaramse aumentados no M2; os animais intoxicados apresentaram anorexia, membranas mucosas ictéricas, fezes amolecidas de coloração verde-escura e hemoglobinúria. À necropsia observou-se mucosas, fígado e demais tecidos de coloração amarelada... / Sheep have a tendency to accumulate copper in the body. When the liver storage capacity is exhausted, copper is released into the blood causing clinical signs of poisoning. Six lambs fed a basal diet were randomly assigned to 2 groups: G - 1 (control) and G-2 (experimentally intoxicated). The three sheep of the G-2, were drenched initially with 3 mg of CuSO4. 5H2O/ kg bw daily for a week. Every week an additional dose of 3mg CuSO4. 5H2O/ kg bw was included in the drench until signs of copper poisoning appeared. Every day, the lambs were monitored clinically. before (M0 – M3), during (M4) and after (M5 and M6) to hemolytic crisis, sample blood were obtained for biochemical analysis of AST, GGT and CK, blood count, serum proteins and serum concentration of copper. The lambs of the G-2 that died in the course of the experiment and the lambs of the G-1 euthanized at the end, were necropsied and fragments of liver, were obtained for histopathology. During the pre-hemolytic phase few changes were evidenced, however thought the hemolytic crisis the sheep of the G-2 were presented macrocytic normochromic anemia, a predominance of erythrocytes with acantocytes morphology, leukocytosis by neutrophilia, elevation in serum activities of AST, GGT and CK and hipercupremia; Serum levels of ceruloplasmin was presented reduced and the levels of transferrin, 35,000 of protein and IgG- light chain were increased in M2; the lambs of G-2 exhibited anorexia, jaundiced mucous membranes, soften and dark-green feces and hemoglobinuria. Gross examination of poisoned lambs revealed mucous membranes, liver and other tissues yellowish, dark kidneys and brownish urine. Histopathology of the liver showed megalocitose of hepatocytes, the disorganization of strands of hepatocytes, cholestasis and inflammatory infiltrate lymphocytic peri-portal.

Made available in DSpace on 2016-12-08T16:24:09Z (GMT). No. of bitstreams: 1 PGCA11MA076.pdf: 565425 bytes, checksum: 106f4453f4dd44cc8cd054b2cb5c67a8 (MD5) Previous issue date: 2011-12-09 / Trypanosoma evansi is a hemoflagellate parasite that had known to cause infection in a variety of mammals, such as camels, cattles, horses, buffaloes, pigs, dogs and other animal species in tropical and subtropical áreas. In Brazil, T. evansi is considered endemic only at Pantanal, but has been also found in the central region of Rio Grande do Sul and Santa Catarina also. High levels of parasitemia with rapid development of anemia characterize the disease, however the mechanisms of development are still unknown. In this study we aimed to investigate the effect of oxidative stress in erythrocytes and evaluate hematological parameters in rats experimentally infected with T. evansi. Due to, sixty male Wistar rats, were inoculated intraperitoneally with blood containing 103 trypanosomes and fifteen were negative control. The parasitemia was evaluated each 12 hours and the animals were allocated in five groups according to average parasitemia in 10 random homogeneous microscopic fields: (A) uninfected group (control); (B) rats with 1-10 trypanosomes/field; (C) 11-30 trypanosomes/field; (D) 31-60 trypanosomes/field; and (E) more than 61 trypanosomes/field. The animals that achieved the number of trypanosomes equivalent to the groups were sacrificed and blood samples collected to measurement the activities of glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), glucose-6-phosphate dehydrogenase (G6PD), catalase (CAT), and glutathione (total and oxidized), protein thiols (PSH) and non-protein (NPSH). As well as, serum iron, plasma glucose, osmotic fragility, methemoglobin levels, markers of oxidative stress as total and lipid peroxides levels and protein carbonyl concentration (PC) were quantified. Hematological parameters were also analyzed such as erythrocyte count, hematocrit, hemoglobin concentration, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin concentration, total plasma proteins, platelets, reticulocytes and differential leukocytes count. The infected groups with greater development of the disease developed anemia, with low reticulocytes and platelets levels. Besides that, the increasing of erythrocyte osmotic fragility and methemoglobin levels was observed in groups D and E. In group E was observed a significant reduction of plasma glucose levels when compared with the control group (64%). The serum iron decreased to 58% in group B, but increased to 78% in group E. The acute infection caused an increase in GPx activity in group C, D and E, and enhances CAT activity in group D and E respectively. However, decreased the GR activity in group E approximately 52%. There were no significant differences in the activities of GST and G6PD in the groups comparing to the control. Infection with T. evansi caused a consumption of GSH-t (48%) and a reduction of the levels of PSH and NPSH, around 55%. As well, infected animals showed an increase of the levels of total and lipid peroxides, more than 90% PC concentration compared with the control. Finally, T. evansi promoted oxidative damage in infected rats through increasing antioxidant activities of GPx, CAT, depletion of GSH-t, PSH and NPSH, and inhibition of GR activity. Moreover, the infection also increased the levels of PC, total and lipid peroxides in higher stages of infection caused by T. evansi. Therefore, we can to state that oxidative damage in erythrocytes contributes decisively to the development of anemia in infection by T. evansi in rats / O Trypanosoma evansi é um hemoparasita flagelado conhecido por causar infecção em uma diversidade de mamíferos como camelos, bovinos, equinos, bubalinos, suínos, caninos e outras espécies animais em áreas tropicais e subtropicais. No Brasil, T. evansi é considerado endêmico apenas no Pantanal, mas também já foi encontrada na região central do Rio Grande do Sul e em Santa Catarina. Altos níveis de parasitemia com rápido desenvolvimento de anemia caracterizam a doença, contudo seus mecanismos de desenvolvimento ainda são desconhecidos. Este estudo teve como objetivo investigar o efeito do estresse oxidativo em eritrócitos e avaliar parâmetros hematológicos de ratos infectados experimentalmente com T. evansi. Para isso, sessenta ratos Wistar machos foram inoculados via intraperitonial com sangue contendo 103 tripanossomas e quinze foram usados como controle negativo. A parasitemia foi avaliada a cada 12 horas e os animais foram alocados em cinco grupos de acordo com a média de tripanossomas em 10 campos homogêneos focados aleatoriamente sendo: (A) grupo não infectado (controle); (B) ratos com 1-10 tripanossomas/campo; (C) 11-30 tripanossomas/campo; (D) 31 a 60 tripanossomas/campo; and (E) com mais de 61 tripanossomas/campo. Os animais que apresentaram o número de tripanossomas equivalente ao grupo, foram sacrificados e amostras de sangue coletadas para mensuração das atividades da glutationa peroxidase (GPx), glutationa redutase (GR), glutationa-S-transferase (GST), glicose-6-fosfato desidrogenase (G6PD), catalase (CAT), e glutationa (total e oxidada), tióis protéicos (PSH) e não protéicos (NPSH). Assim como ferro sérico, glicose plasmática, fragilidade osmótica, níveis de metahemoglobina, marcadores de estresse oxidativo como peróxidos totais e lipídicos e níveis de proteína carbonilada (PC) foram quantificados. Também foram analisados parâmetros hematológicos tais como contagem total eritrócitos, hematócrito, concentração de hemoglobina, volume globular, volume globular médio, concentração hemoglobina corpuscular média, proteínas plasmáticas totais, plaquetas, reticulócitos, e contagem diferencial de leucócitos. Os grupos infectados com maior desenvolvimento da doença apresentaram anemia, com diminuição nos reticulócitos e plaquetas. Além disso, o aumento na fragilidade osmótica eritrocitária e nos níveis de metahemoglobina nos grupos D e E foi observada. No grupo E foi observada uma redução significativa nos níveis de glicose plasmática quando comparado ao grupo controle (64%). O ferro sérico diminuiu 78% no grupo B, mas aumentou 78% no grupo E. A infecção aguda causou um aumento da atividade da GPx nos grupos C, D e E e um aumento da atividade da CAT nos grupos D e E respectivamente. Entretanto, ocorreu uma diminuição da atividade da GR no grupo E de aproximadamente 52%. Não foram encontradas diferenças significativas nas atividades da GST e G6PD nos grupos comparados com o controle. Infecção com T. evansi causou um consumo da GSH-t (48%) e uma redução nos níveis de PSH e NPSH, de aproximadamente 55%. Assim como, animais infectados mostraram um aumento nos níveis de peróxidos totais e lipídicos, na concentração de PC de mais de 90% comparado com o controle. Em resumo, T. evansi promoveu insulto oxidativo em ratos infectados através do aumento das atividades da GPx, CAT, depleção da GSH-t, PSH e NPSH, inibição da atividade da GR. Além disso, a infecção também aumentou os níveis de PC, peróxidos totais e lipídicos nos estágios de maior infecção causada pelo T. evansi. Diante disso, é possível afirmar que danos oxidativos em eritrócitos contribuem decisivamente para o desenvolvimento de anemia na infecção por T. evansi em ratos

Made available in DSpace on 2014-12-17T14:16:23Z (GMT). No. of bitstreams: 1 DeboraAN.pdf: 367004 bytes, checksum: a62b214f06755ba9b9d2aedbea46c4f9 (MD5) Previous issue date: 2006-05-24 / This study aimed builds reference values for copper and zinc, of healthy adults in Natal-RN, and to identify the influence of the gender, age, body mass index (BMI) and diet, on those values. They were assessed 123 healthy students of the Universidade Federal do Rio Grande do Norte (UFRN), both genders, with age between 19 and 41 years. The project was approved by the Ethics Committee in Research of UFRN. BMI was determined and the food consume was accomplished through a 24h recordatory. Dietary was evaluated as the energy, macronutrients, copper and zinc, according to the recommendations of National Academy of Sciences (2001; 2002). Analyses of the copper and zinc concentrations in the plasma and erythrocytes were accomplished by flame atomic absorption spectrometry. The casuistic came quite homogeneous as for the distribution for gender and age, being the largest number of individuals between the 19 and 24 years old. Most of the volunteers presented anthropometric nutritional state inside of the normality patterns. Chronic diseases family antecedents and sedentarysm were observed. Diet was characterized with low consumption of zinc, appropriate of copper and of lipids. Average concentrations of plasma copper (p=0,002), erythrocyte copper (μg/dL, p=0,036; μg/gHb, p=0,038), and plasma zinc (p=0,022) were different among the genders, what was demonstrated by the largest values of copper in the female gender and larger of zinc in the masculine. Plasma copper values still suffered interference of the variables: energy, carbohydrate and copper consumption, all classified in agreement with the median, besides the protein classified according to the percentage contribution for the dietary total energy. The study allowed to establish reference values for erythrocyte zinc (1.261,6-1.344,0 μg/dL e 51,0-54,3 μg/gHb) and to suggest "indicative" of reference values for plasma (108,4 130,2 μg/dL) and erythrocyte (female = 85,0 91,4 μg/dL; masculine = 80,2 86,5 μg/dL) copper and plasma zinc (female = 98,8 105,8 μg/dL; masculine = 104,6 111,6 μg/dL) / O estudo teve como objetivo construir valores de refer?ncia para cobre e zinco, de adultos saud?veis na cidade do Natal-RN, e identificar a influ?ncia do g?nero, idade, ?ndice de massa corporal (IMC) e dieta, sobre esses valores. Foram avaliados 123 estudantes saud?veis da Universidade Federal do Rio Grande do Norte (UFRN), de ambos os g?neros, com idade entre 19 e 41 anos. O projeto foi aprovado pelo Comit? de ?tica em Pesquisa da UFRN. Foi estimado o indice de massa corporal e realizado um recordat?rio alimentar de 24h. A dieta foi avaliada quanto a energia, macronutrientes, cobre e zinco, segundo as recomenda??es da National Academy of Sciences (2001; 2002). As concentra??es de cobre e zinco no plasma e no eritr?cito foram realizadas por espectrofotometria de absor??o at?mica de chama. A casu?stica apresentou-se bastante homog?nea quanto ? distribui??o por g?nero e idade, estando o maior n?mero de indiv?duos entre os 19 e 24 anos. A maioria dos volunt?rios apresentou estado nutricional antropom?trico dentro dos padr?es de normalidade. Antecedentes familiares de doen?as cr?nicas e sedentarismo foram observados. A dieta caracterizou-se com baixo consumo de zinco, adequado de cobre e de lip?deos. As concentra??es m?dias de cobre no plasma (p=0,002), cobre no eritr?cito (μg/dL, p=0,036; μg/gHb, p=0,038), e zinco no plasma (p=0,022), foram estatisticamente diferentes entre os g?neros, o que foi demonstrado pelos maiores valores de cobre do g?nero feminino e maiores de zinco no masculino. Os valores de cobre no plasma sofreram ainda interfer?ncia das vari?veis: ingest?o de calorias, carboidrato e cobre na dieta, todos categorizados de acordo com a mediana, al?m da prote?na categorizada segundo o percentual de contribui??o para o valor cal?rico total (VCT) da dieta. O estudo permitiu estabelecer valores de refer?ncia para zinco no eritr?cito, correspondentes a 1.261,6-1.344,0 μg/dL e 51,0-54,3 μg/gHb, e sugerir indicativos de valores de refer?ncia para cobre no plasma (108,4 130,2 μg/dL), no eritr?cito (feminino = 85,0 91,4 μg/dL; masculino = 80,2 86,5 μg/dL) e zinco no plasma (feminino 98,8 105,8 = μg/dL; masculino 104,6 111,6 = μg/dL)

Heat Shock 40 kDa proteins (Hsp40s) partner with heat shock 70 kDa proteins (Hsp70s) in facilitating, among other chaperone activities; correct protein transport, productive protein folding and assembly within the cells; under both normal and stressful conditions. Hsp40 proteins regulate the ATPase activity of Hsp70 through interaction with the J-domain. Plasmodium falciparum Hsp70s (PfHsp70s) do not contain a Plasmodium export element (PEXEL) sequence although PfHsp70-1 and PfHsp70-3 have been located outside of the parasitophorous vacuole. Studies reveal that a type I P. falciparum (PfHsp40) chaperone (PF14_0359) stimulates the rate of ATP hydrolysis of the cytosolic PfHsp70 (PfHsp70-1) and that of human Hsp70A1A. PFE0055c is a PEXEL-bearing type II Hsp40 that is exported into the cytosol of P. falciparum-infected erythrocytes; where it potentially interacts with human Hsp70. Studies reveal that PFE0055c associates with structures found in the erythrocyte cytosol termed “J-dots” which are believed to be involved in trafficking parasite-encoded proteins through the erythrocyte cytosol. If P. falciparum exports PFE0055c into the host cytosol, it may be proposed that it interacts with human Hsp70, making it a possible drug target. The effect of PFE0055c on the ATPase activity of human Hsp70A1A has not been previously characterised. Central to this study was bioinformatic analysis and biochemical characterisation PFE0055c using an in vitro (ATPase assay) approach. Structural domains that classify PFE0055c as a type II Hsp40 were identified with similarity to two other exported type II PfHsp40s. Plasmids encoding the hexahistidine-tagged versions of PFE0055c and human Hsp70A1A were used for the expression and purification of these proteins from Escherichia coli. Purification was achieved using nickel affinity chromatography. The urea-denaturing method was used to obtain the purified PFE0055c whilst human Hsp70A1A was purified using the native method. PFE0055c could stimulate the ATPase activity of alfalfa Hsp70, although such was not the case for human Hsp70A1A in vitro.

Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.