Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2009.

Background: In South Africa, as in many other developing countries, iron deficiency (the most common micronutrient deficiency) still remains unresolved; while obesity has emerged as a public health challenge causing increases in the incidence and prevalence of cardiovascular diseases (CVDs). Research has shown that certain iron indices are associated with both anthropometric and biological markers of CVDs. Adiposity is thought to modulate the pathway linking iron status to CVDs. Objective: To examine the associations between iron indices, anthropometric and biological markers of CVDs in an African population undergoing transition. Methods: This thesis was based on secondary analysis of data generated during the Transition and Health during Urbanisation of South Africans (THUSA) study; and primary and secondary analysis of the baseline Prospective Urban and Rural Epidemiological (PURE) study. Both studies were cross–sectional in design and were conducted between 1996–1998 and in 2005 respectively in the North West Province of South Africa. The 1854 men and women participants in the THUSA study (>15years) and 1262 women participants in the PURE study (>35years) were included in the analysis. The relationship between iron and anthropometric indicators of CVD risk was examined in the THUSA study while that of iron status, anthropometric and biological markers of CVD risk was examined in the PURE study. Results: In the THUSA study, ferritin was positively associated with body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), body fat and subscapular skinfold (r=0.141, 0.359, 0.396, 0.308, 0.141 respectively for men and 0.126, 0.232, 0.319, 0.126, 0.105 respectively for women; p<0.01). Only the women showed decreased serum iron concentration with increasing BMI (p<0.05). WC and WHR increased with increasing serum ferritin concentration for both genders (p<0.05). As for the PURE study, associations between iron status parameters and CVD risk factors were generally weak (r<0.3, p<0.01) and were not retained after adjusting for valid confounders. WC and WHR increased with increasing ferritin concentration (p<0.05). Conclusion: Although these results do not indicate any significant association between iron indices and biological markers of CVD, its association with anthropometric indices gives an indication of the possible contribution of iron in the aetiology of CVDs. Thus, it may be necessary to exercise caution on the emphasis placed on iron as a nutrient and iron intervention programmes because of the suggestive role of iron in CVD development. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2011.

Les relations bien connues en cas d'hémochromatose entre surcharge en fer, insulinorésistance et stress oxydant, nous ont conduit à chercher à établir le rôle de la ferritine comme un facteur prédictif du risque de diabète gestationnel et du stress oxydant indépendamment de toute supplémentation dans une population de femmes Libanaises non anémiques. Nous avons observé qu'une ferritine élevée en début de la grossesse était un facteur prédictif d'intolérance au glucose, alors que cette relation n'était pas retrouvée avec une hémoglobine élevée, suggérant que le fer de réserve est un facteur de risque à considérer et non pas le fer fonctionnel. Le dosage de la ferritine pourrait être un marqueur biologique à prendre en considération pour évaluer le risque d'intolérance au glucose chez les femmes à risque de diabète gestationnel. La prévalence du diabète gestationnel dans la population étudiée, sur la base de nouveaux critères adoptés par l'Organisation mondiale de la santé était de ~15% alors qu'elle n'était que de 4% avec les critères de O'Sullivan actuellement utilisés dans les hôpitaux où a été recrutée notre population. Cette forte différence souligne la nécessité de l'adoption de nouveaux critères pour un meilleur dépistage et une meilleure prise en charge du fait des risques materno-fœtaux associés au diabète gestationnel. Malgré l'abaissement des valeurs de la glycémie, nous montrons que les nouveaux seuils de glycémie définissant désormais un diabète gestationnel sont toujours associés à une augmentation du stress oxydant, notamment des dommages à l'ADN. Conformément à la littérature, nous montrons qu'un statut en fer élevé, est associé à un état de stress oxydant élevé. De façon plus originale nous montrons qu'une ferritine élevée en début de grossesse aggrave l'association du stress oxydant et de l'insulinorésistance avec l'intolérance au glucose. En l`absence de modèle satisfaisant pour l`étude du diabète gestationnel expérimental, nous avons validé dans une étude préliminaire un régime riche en fructose comme modèle expérimental de diabète gestationnel. Nous montrons que ce modèle induit les mêmes modifications chez les rates et leurs ratons que celles observées lors de diabète gestationnel, de plus lorsque ce régime est enrichi en fer, des altérations oxydatives sont observées au niveau cérébral et hépatique des ratons. Ce modèle expérimental nous permettra d'étudier ultérieurement les voies de signalisation qui régissent les interactions entre fer, stress oxydant et diabète gestationnel et d'évaluer les répercussions d'une augmentation des dommages oxydatifs chez les fœtus, chez les nouveau-nés à la naissance et à distance par des études de comportement. Enfin en raison des données récentes sur l'épigénétique notre modèle expérimental pourrait nous permettre de suivre l'évolution en terme d'apparition de pathologies à l'âge adulte (insulinorésistance, diabète de type 2, déclin cognitif) des animaux nés de mère avec un diabète gestationnel. Au vu de l`ensemble de nos résultats sur les interactions entre ferritine, intolérance au glucose et stress oxydant, le bénéfice d`une supplémentation martiale durant la grossesse chez des femmes à risque de diabète gestationnel doit être évalué. / The overall goal of this study was to establish the role of ferritin as a predictor for gestational diabetes mellitus and oxidative stress in non-anemic and non-iron supplemented Lebanese women. We observed that high ferritin level during the first-trimester of pregnancy was a predictor for impaired glucose tolerance, whereas high hemoglobin values yielded no significant relationship, suggesting that the iron reserve was the main indicator to be considered as a risk factor rather than the functional iron. Thus, the serum ferritin level could be used as a biological marker to assess for the risk of glucose intolerance in pregnant women. Based on the new World Health Organization criteria for gestational diabetes mellitus diagnosis, it is predicted that gestational diabetes mellitus prevalence in our population could be increased by four-fold. Since gestational diabetes mellitus has deleterious effects on the perinatal and maternal health outcomes, the implementation of these new criteria will allow for better management of blood glucose in pregnant women at risk for developing gestational diabetes mellitus. Although the new criteria adopted lower cut-off blood glucose value, hyperglycemia is still a factor that highly associated with increase oxidative stress, ultimately leading to DNA damage. Previously, we have shown that high iron status was associated with elevated oxidative stress. Furthermore, we have established that high ferritin during early-term pregnancy affected the association between oxidative stress and insulin resistance with glucose intolerance. Due to the lack of good experimental model to study gestational diabetes mellitus, we have utilized fructose-supplemented diet fed pregnant dam as an experimental animal model for our gestational diabetes studies. Data obtained in a preliminary study indicated that, this experimental animal model had identical metabolic modifications found in women with gestational diabetes mellitus. Moreover, we have showed that iron-enriched diet significantly increased the redox status of the brain and the liver of the fructose-supplemented dams. Therefore, we believed that this experimental model is good model for future studies to evaluate the signaling pathways involved in iron, oxidative stress and gestational diabetes and to assess the impact of increased oxidative damage during pregnancy on the fetus, immediately after birth and later during the developmental stages via various behavioral tests. Finally, an epigenetic study using this experimental model may allow us to understand the genetic alterations that affected the likelihood of developing insulin resistance, diabetes, or cognitive decline in pups born to the mothers with gestational diabetes. Based on the findings from our studies on the interaction between ferritin, glucose impairment, and oxidative stress, as well as the iron-supplemented diet in the dams with gestational diabetes mellitus, a caution must be exercised when supplementing a pregnant woman with iron. The use of iron-supplementation during pregnancy should be re-evaluated.

Introdução: O transplante de células tronco hematopoiéticas é reconhecidamente uma opção terapêutica para doenças neoplásicas hematológicas, tumores sólidos, deficiências imunológicas e doenças metabólicas. É um procedimento associado a uma alta freqüência de complicações agudas e crônicas, causadas pela toxicidade do regime de condicionamento, dentre elas a mucosite, Doença do Enxerto versus Hospedeiro - DECH e infecções. Essas complicações podem causar grandes mudanças na composição corporal através de mudanças no metabolismo, piorando o estado nutricional. Um adequado consumo de alguns micronutrientes como zinco, vitamina D e ferro, tem sido investigado como forma de evitar ou minimizar essas complicações. Objetivo: Avaliar em pacientes submetidos a transplante de células tronco hematopoiéticas os níveis séricos de zinco, vitamina D e ferritina e o seu impacto nos desfechos do TCTH alogênico e os níveis de ingestão de zinco, vitamina D e ferro. Métodos: Foram avaliadas as dosagens séricas de zinco, vitamina D e ferritina, e os níveis de ingestão de zinco, vitamina D e ferro, os tipos de condicionamento, o grau de DECH e mucosite, a presença de infecções e o estado nutricional. Resultado: Foram incluídos na análise 32 pacientes. Não foi encontrado associação significativa entre a deficiência sérica de Zinco e mucosite e os níveis elevados de ferritina sérica com a ocorrência de infecções. Deficiência sérica de vitamina D aos 45 dias pós transplante foi associado com o desenvolvimento de DECH. Conclusão: Os nossos resultados reforçam a importância dos pacientes manterem os níveis adequados de micronutrientes e reforçam o papel da vitamina D na prevenção de DECH durante o TCTH. / Introduction: The transplantation of hematopoietic stem cells is recognized as a treatment option for hematological neoplastic diseases, solid tumors, immune deficiencies and metabolic diseases. It is a procedure associated with a high frequency of acute and chronic complications caused by the toxicity of the conditioning regimen, among them mucositis, Graft-versus-Host Disease - GVHD and infections. These complications can cause major changes in body composition through changes in metabolism, worsening the nutritional status. An adequate intake of some micronutrients such as zinc, vitamin D and iron, has been investigated as a way to avoid or minimize these complications. Objective: To evaluate in patients undergoing hematopoietic stem cell transplantation serum levels of zinc, vitamin D and ferritin and its impact on the outcomes of allogeneic HSCT and zinc intake levels of vitamin D and iron. Method: The following aspects were evaluated: serum levels of zinc, vitamin D and ferritin, and zinc intake levels of vitamin D and iron, the conditioning types, the degree of GVHD and mucositis, the presence of infections, the nutritional status. Result: The analysis included 32 patients. No significant association has been found between zinc serum deficiency and mucositis and elevated levels of serum ferritin with the occurrence of infections. The serum deficiency of vitamin D at 45 days post-transplantation has been associated with the development of GVHD. Conclusion: Our results reinforce that it is important for the patients to maintain adequate levels of micronutrients and reinforce the role of vitamin D in the prevention of GVHD during the HSCT. Keywords: hematopoietic stem cell transplantation, GVHD, mucositis, infections, Vitamin D, ferritin, zinc, nutritional status.

Introdução: O transplante de células tronco hematopoiéticas é reconhecidamente uma opção terapêutica para doenças neoplásicas hematológicas, tumores sólidos, deficiências imunológicas e doenças metabólicas. É um procedimento associado a uma alta freqüência de complicações agudas e crônicas, causadas pela toxicidade do regime de condicionamento, dentre elas a mucosite, Doença do Enxerto versus Hospedeiro - DECH e infecções. Essas complicações podem causar grandes mudanças na composição corporal através de mudanças no metabolismo, piorando o estado nutricional. Um adequado consumo de alguns micronutrientes como zinco, vitamina D e ferro, tem sido investigado como forma de evitar ou minimizar essas complicações. Objetivo: Avaliar em pacientes submetidos a transplante de células tronco hematopoiéticas os níveis séricos de zinco, vitamina D e ferritina e o seu impacto nos desfechos do TCTH alogênico e os níveis de ingestão de zinco, vitamina D e ferro. Métodos: Foram avaliadas as dosagens séricas de zinco, vitamina D e ferritina, e os níveis de ingestão de zinco, vitamina D e ferro, os tipos de condicionamento, o grau de DECH e mucosite, a presença de infecções e o estado nutricional. Resultado: Foram incluídos na análise 32 pacientes. Não foi encontrado associação significativa entre a deficiência sérica de Zinco e mucosite e os níveis elevados de ferritina sérica com a ocorrência de infecções. Deficiência sérica de vitamina D aos 45 dias pós transplante foi associado com o desenvolvimento de DECH. Conclusão: Os nossos resultados reforçam a importância dos pacientes manterem os níveis adequados de micronutrientes e reforçam o papel da vitamina D na prevenção de DECH durante o TCTH. / Introduction: The transplantation of hematopoietic stem cells is recognized as a treatment option for hematological neoplastic diseases, solid tumors, immune deficiencies and metabolic diseases. It is a procedure associated with a high frequency of acute and chronic complications caused by the toxicity of the conditioning regimen, among them mucositis, Graft-versus-Host Disease - GVHD and infections. These complications can cause major changes in body composition through changes in metabolism, worsening the nutritional status. An adequate intake of some micronutrients such as zinc, vitamin D and iron, has been investigated as a way to avoid or minimize these complications. Objective: To evaluate in patients undergoing hematopoietic stem cell transplantation serum levels of zinc, vitamin D and ferritin and its impact on the outcomes of allogeneic HSCT and zinc intake levels of vitamin D and iron. Method: The following aspects were evaluated: serum levels of zinc, vitamin D and ferritin, and zinc intake levels of vitamin D and iron, the conditioning types, the degree of GVHD and mucositis, the presence of infections, the nutritional status. Result: The analysis included 32 patients. No significant association has been found between zinc serum deficiency and mucositis and elevated levels of serum ferritin with the occurrence of infections. The serum deficiency of vitamin D at 45 days post-transplantation has been associated with the development of GVHD. Conclusion: Our results reinforce that it is important for the patients to maintain adequate levels of micronutrients and reinforce the role of vitamin D in the prevention of GVHD during the HSCT. Keywords: hematopoietic stem cell transplantation, GVHD, mucositis, infections, Vitamin D, ferritin, zinc, nutritional status.

The aim of this cross-sectional study was to compare MRI with liver biopsy as a tool for identification and quantification of liver iron overload in patients with sickle cell anemia using blood transfusions. We compared the results of the baseline serum ferritin in the absence of acute complications, the estimated liver iron concentration by magnetic resonance imaging and semiquantitative determination of iron in a fragment of liver tissue obtained by percutaneous biopsy. We observed a statistically significant correlation (r = 0.75) between the degree of iron overload identified in a fragment of liver tissue (Scheuer criteria) and the estimated mean concentration of iron calculated from the intensity of the signal detected by MRI (p = 0.0007). This relationship persists when we aggregate the results in two groups: without or minimal overload (Scheuer zero and one) and presence of overload (Scheuer 2- 4), p = 0.004. MRI was able to differentiate patients with and without iron overload when compared with histological data. MRI is a non-invasive method and can be used to replace liver biopsy for monitoring patients with sickle cell anemia when there is no associated liver disease. To date, this is the first study to make this assessment in patients with sickle cell anemia. / Este trabalho propôs-se a comparar ressonância magnética (RM) com biópsia hepática como ferramentas para identificação e quantificação da sobrecarga hepática de ferro em pacientes portadores de anemia falciforme (AF) que utilizam transfusão de hemácias. Com delineamento transversal, neste estudo foram comparados os resultados da dosagem de ferritina sérica basal (na ausência de intercorrências agudas), da concentração hepática estimada de ferro através de ressonância magnética, e da determinação semiquantitativa de ferro em fragmento de tecido hepático (critérios de Scheuer) obtido por biópsia percutânea. Observou-se correlação estatisticamente significativa (r = 0,75) entre os cinco graus de sobrecarga de ferro identificada em fragmento de tecido hepático e a concentração média estimada de ferro calculada a partir da intensidade de sinal detectada por RM (p = 0,0007), relação que se mantém quando se agrupa os resultados em categorias sem sobrecarga ou sobrecarga discreta (Scheuer zero e 1) e com sobrecarga (Scheuer 2 a 4), com p = 0,004. A RM foi capaz de diferenciar pacientes com e sem sobrecarga de ferro quando comparada aos dados histológicos. Por ser método não-invasivo pode ser utilizado em substituição à biópsia hepática para seguimento dos pacientes com AF, quando não houver doença hepática associada. Até o momento, é o primeiro estudo a fazer essa avaliação em pacientes com AF.

As síndromes talassêmicas (?- e ?-talassemia) são as desordens mais comuns e frequentes associadas com eritropoese ineficaz. O desbalanço na produção das cadeias ?- e ?-globinas resulta no comprometimento da produção de eritrócitos, em anemia e aumento de progenitores eritroides no sangue periférico. Enquanto os pacientes homozigóticos afetados por essas desordens demonstram alterações características dos parâmetros relacionados a eritropoese, a relação entre grau de anemia, eritropoese alterada e disfunção do metabolismo de ferro ainda não foram investigados nos indivíduos com ?+-talassemia heterozigótica ou ?+-talassêmia. Duzentos e vinte seis indivíduos (75 do gênero feminino e 151 do gênero masculino) foram recrutados e divididos em 5 grupos: Controle (n=28), doadores de sangue regulares (DSR, n=23), ?+-talassemia heterozigótica (TAT, n=14), ?+-thalassemia (traço ?-talassêmico, TBT, n=20) e ?0-talassemia, (?-talassemia maior, BTM, n=27). As amostras foram analisadas para parâmetros hematológicos (Micros ABX 60); ferro sérico, capacidade total de ligação ao ferro e saturação de transferrina por método colorimétrico (Pointe Scientific, Inc., Canton, MI, USA), ferritina e proteína C-reativa ultra sensível por imunoensaio (Immulite 1000); receptor solúvel de transferrina, eritropoetina, fator de diferenciação do crescimento 15 (R&D Systems) e hepcidina (Intrinsic LifeSciences, La Jolla, CA) por ELISA. As razões sTfR/log ferritina e (hepcidina/ferritina)/sTfR foram calculadas para avaliar o metabolismo do ferro. sTfR/log ferritina pode distinguir depleção dos estoques de ferro de eritropoese deficiente de ferro, enquanto (hepcidina/ferritina)/sTfR pode avaliar os estímulos contrários (disponibilidade de ferro e atividade eritropoética) que controlam a síntese de hepcidina e a absorção de ferro, na ausência de estímulos inflamatórios. Foi demonstrado que TAT teve significativa redução da hepcidina e aumento do receptor solúvel de transferrina, com parâmetros hematológicos relativamente normais. Em contraste, todos os parâmetros hematológicos de TBT foram significativamente diferentes do Controle, incluindo aumento dos níveis do receptor solúvel de transferrina, ferritina, eritropoetina e fator de diferenciação do crescimento 15. Essas alterações em ambos os grupos sugerem um balanço alterado entre eritropoese e metabolismo de ferro. Os índices sTfR/log ferritina e (hepcidina/ferritina)/sTfR estão, respectivamente, aumentado e reduzido comparados ao Controle, proporcional a severidade de cada grupo talassêmico. Em conclusão, destacamos que, pela primeira vez, foram descritas alterações no metabolismo de ferro em indivíduos com ?+-talassemia heterozigótica. Esses dados demonstram que, no contexto da saúde pública, são necessários identificação e acompanhamento dos portadores de ?+-talassemia. / The thalassemia syndromes (?- and ?-thalassemia) are the most common and frequent disorders associated with ineffective erythropoiesis. Imbalance of ?- or ?-globin chain production results in impaired red blood cell synthesis, anemia and more erythroid progenitors in the blood stream. While patients affected by these disorders show definitive altered parameters related to erythropoiesis, the relationship between the degree of anemia, altered erythropoiesis and dysfunctional iron metabolism have not been investigated in both carriers of ?-thalassemia and ?-thalassemia. 226 subjects (75 females and 151 males) were recruited to this study and divided in 5 groups: Control (n=28), repeat blood donors (DSR, n=23), ?+-thalassemia heterozygous carriers (TAT, n=14), ?+-thalassemia (?-thalassemia trait, TBT, n=20) and ?0-thalassemia, (?-thalassemia major, BTM, n=27). Samples were tested for hematological parameters (Micros ABX 60); serum iron, total iron binding capacity, and transferrin saturation by the colorimetric method (Pointe Scientific, Inc., Canton, MI, USA), ferritin and high sensitive C-reactive protein by immunoassay (Immulite 1000); soluble transferrin receptor, erythropoietin and growth differentiation factor 15 (R&D Systems) and hepcidin (Intrinsic LifeSciences, La Jolla, CA) by ELISA. Were calculated the ratios sTfR/log ferritin and (hepcidin/ferritin)/sTfR to evaluate iron metabolism. sTfR/log ferritin can distinguish storage iron depletion from iron-deficient erythropoiesis, while (hepcidin/ferritin)/sTfR can be utilized to explore and quantify the opposing forces (i.e. iron availability and erythropoietic activity) regulating hepcidin synthesis and iron absorption in absence of inflammatory stimuli. We demonstrate that TAT have a significantly reduced hepcidin and increased soluble transferrin receptor levels but relatively normal hematological findings. In contrast, TBT have all hematological parameters significantly different from controls, including increased soluble transferrin receptor, ferritin, erythropoietin and growth differentiation factor 15 levels. These changings in both groups suggest an altered balance between erythropoiesis and iron metabolism. The indexes sTfR/log ferritin and (hepcidin/ferritin)/sTfR are respectively increased and reduced relative to controls, proportional to the severity of each thalassemia group. In conclusion, we emphasize that, for the first time in the literature, subjects with heterozygous ?+-thalassemia have altered iron metabolism. Our data demonstrate that within the context of public health, identification and monitoring of patients with ?+-thalassemia are needed.

Anemia in Leptospira interrogans infected individuals is one of the most common complications found in the severe form of the disease. Iron plays an important role in the hematopoietic processes; however, its precise metabolism on individuals with leptospirosis is still unknown. Therefore, the aim of this study was to analyze the classic iron markers associated to the storage process in hamsters experimentally infected by L. interrogans serovar Pomona (virulent strain LPF). Four groups with six hamsters each were used; two groups were controls (C7 and C14) and two were experimental groups with infected animals (T7 and T14). Blood samples were collected on the seventh (C7 and T7) and fourteenth days (C14 and T14) post-inoculation (PI). Iron availability was determined in sera samples by the assessment of iron, ferritin, transferrin, and iron binding capacity, whereas the bone marrow was also evaluated for the deposition of this metal by Pearl s reaction. Additionally, the total antioxidant capacity (TAC) and total oxidant status (TOS) were assessed, along with hepcidin and IL-6 levels to be involved in iron metabolism. Based on the results, it was possible to observe the onset of an acute condition with crisis hemolytic and regenerative response. The other parameters showed an increase in seric iron, ferritin, as well as a positive Pearl s reaction in animals from the groups T7 and T14 compared with the control groups. Transferrin levels decreased in animals from the group T14 with saturation index, but without statistical difference among all tested groups. TAC was increased in both periods, while TOS was increased only on day 14 PI. Hepcidin and IL-6 were statistically increased on days 7 and 14 PI. Therefore, it was observed that the serum profile from infected animals showed a strong hemolytic pattern, with some demonstration of ferric tissue sequestration. The results show that iron metabolism is activated in hamsters infected by L. interrogans sorovar Pomona, and therefore has participation in the pathogenesis of the disease. / A ocorrência de anemia em indivíduos infectados por Leptospira interrogans é uma das complicações decorrentes à doença em sua forma mais severa. O ferro tem um papel importante nos processos hematopoiéticos, no entanto, o seu metabolismo preciso em indivíduos com leptospirose ainda é desconhecido. Portanto, o objetivo deste trabalho foi analisar os marcadores clássicos relativos à reserva de ferro no organismo de hamsters experimentalmente infectados com L. interrogans sorovar Pomona, estirpe virulenta LPF. Para isto, foram utilizados 24 hamsters machos, distribuídos em quatro grupos, sendo dois grupos Controles (C7 e C14) e dois Testes (T7 e T14), com 6 animais em cada grupo. Amostras de sangue foram coletadas no sétimo (Grupos C7 e T7) e no décimo quarto dias pós-inoculação (Grupos C14 e T14). A disponibilidade de ferro foi determinada no soro, pela dosagem de ferro sérico, ferritina, transferrina e capacidade de ligação do ferro, ao passo que a medula óssea também foi quantificada quanto à deposição de ferro, através da reação de Pearls. Além disso, a capacidade antioxidante total (CAT) e status total de oxidantes (TOS) foram avaliados, em conjunto com hepcidina e os níveis de IL-6, por serem variáveis envolvidas no metabolismo do ferro. Com os resultados, foi possível observar a instalação de um quadro agudo com crise hemolítico-regenerativa. Nos demais parâmetros, encontrou-se uma elevação do ferro sérico, ferritina, e da positividade na Reação de Pearls, nos dois grupos teste em relação aos controles. A transferrina apresentou uma redução no grupo T14, com índices de saturação, no entanto, sem diferença estatística entre os grupos. Capacidade antioxidante total foi aumentada em ambos os períodos , enquanto TOS foi aumentada apenas no dia 14 PI . Hepcidina e IL-6 foram significativamente elevados nos dias 7 e 14 de PI . Portanto , observou-se que o perfil sérico de animais infectados apresentam um forte padrão hemolítico, com alguma demonstração de sequestro tecidual férrico. Os resultados mostram que o metabolismo do ferro é alterado em hamsters infectados por L. interrogans sorovar Pomona, e que, portanto, tem participação na patogenia da doença.

Staphylococcus xylosus est couramment utilisé comme ferment dans les produits carnés pour son rôle dans le développement de la flaveur et de la couleur. Beaucoup de propriétés technologiques ont été caractérisées in vitro. Cependant, les mécanismes moléculaires mis en place par cette bactérie pour s’adapter à une matrice carnée et aux composés nitrosés, fréquemment ajoutés dans ces produits, étaient méconnus. Pour identifier ces mécanismes, des approches de transcriptomique globale ont été mises en œuvre. S. xylosus survit dans un modèle viande en modulant l’expression de 55 % de ses gènes. Il surexprime des gènes codant des protéines impliqués dans le catabolisme du glucose et du gluconate et des gènes codant des peptidases. En parallèle, il sous exprime de nombreux gènes impliqués dans la synthèse des acides aminés probablement en raison de leur disponibilité dans le modèle viande. Le modèle viande est un milieu riche en divers substrats et la bactérie pourrait adapter sa physiologie via les régulateurs transcriptionnels CcpA et CodY. S. xylosus répond au sel ajouté au modèle viande en surexprimant des gènes impliqués dans des mécanismes d’osmoprotection, d’extrusion de Na + et de protons. S. xylosus répond aux composés nitrosés dans le modèle viande en modulant 24 % de son génome. Ces composés nitrosés génèrent un stress nitrosant et S. xylosus répond à ce stress par la surexpression de gènes impliqués dans l’homéostasie du fer via la dérépression du régulateur Fur. S. xylosus surexprime aussi des gènes codant des enzymes antioxydants via la dérépression du régulateur PerR. De plus, il surexprime des gènes impliqués dans la réparation de l’ADN et des protéines. La viande est un aliment riche en fer hémique et non hémique. Ainsi, S. xylosus est capable d’acquérir du fer à partir de ferritine, de transferrine et potentiellement des hémoprotéines. La ferritine est une source préférentielle de fer pour S. xylosus. Un opéron codant potentiellement un complexe membranaire impliqué dans des réactions d’oxydo-réduction a été identifié. Un mutant de délétion/insertion dans le premier gène de l’opéron confirme que ce système pourrait jouer un rôle dans l’acquisition du fer de la ferritine chez S. xylosus. Cette étude révèle un changement global dans l’expression des gènes de S. xylosus dans un modèle viande, elle souligne la capacité de S. xylosus à s’adapter à un stress osmotique ou nitrosant et elle caractérise pour la première fois la capacité d’un staphylocoque à utiliser du fer de la ferritine. / Staphylococcus xylosus is used as starter culture in meat product for its role in the development of flavor and color. S. xylosus is characterized for its technological properties in vitro. However, the molecular mechanisms for its adaptation in meat with or without nitrate and nitrite, frequently added in meat product, remained unknown. Global transcriptomic approaches were carried out to determine the molecular mechanisms. S. xylosus modulated the expression of 55 % of the genes to survive in a meat model. Many genes encoding proteins involved in glucose and gluconate catabolisms and peptidases were up expressed. In parallel, a lot of genes involved in amino acids synthesis were down regulated, probably due to their availability in the meat model. The meat model is a rich medium composed of various substrates and S. xylosus adapted its physiology through the transcriptional regulators CcpA and CodY. Finally, it responded to salt added in the meat model in overexpressing genes involved in mechanisms of osmoprotection, Na + and H + extrusion. S. xylosus modulated the expression of 24 % of the genes in presence of nitroso compounds in the meat model. These compounds generated a nitrosative stress. S. xylosus responded to this stress by over expressing genes involved in iron homeostasis through the derepression of the regulator Fur. It over expressed also genes encoding antioxidant enzymes through the derepression of the regulator PerR. Moreover, it over expressed genes involved in DNA and proteins repairs. Meat is rich in hemic and non-hemic iron. S. xylosus is able to grow in presence of ferritin, transferrin and potentially hemoproteins. Ferritin is one of preferential iron sources. An operon encoding potentially a membranous complex involved in oxydo-reduction reactions has been identified. A strain defective in the first gene of the operon confirmed that this complex could contribute to the iron acquisition from ferritin. This study revealed a global change in the gene expression of S. xylosus in the meat model; it highlighted ability of S. xylosus to mitigate nitrosative or osmotic stress, it characterised for the first time the capacity of a Staphylococcus to acquire ferritin-iron.

Triple A syndrome is caused by mutations in AAAS encoding the protein ALADIN. We investigated the role of ALADIN in the human adrenocortical cell line NCI-H295R1 by either over-expression or down-regulation of ALADIN. Our findings indicate that AAAS knock-down induces a down-regulation of genes coding for type II microsomal cytochrome P450 hydroxylases CYP17A1 and CYP21A2 and their electron donor enzyme cytochrome P450 oxidoreductase, thereby decreasing biosynthesis of precursor metabolites required for glucocorticoid and androgen production. Furthermore we demonstrate that ALADIN deficiency leads to increased susceptibility to oxidative stress and alteration in redox homeostasis after paraquat treatment. Finally, we show significantly impaired nuclear import of DNA ligase 1, aprataxin and ferritin heavy chain 1 in ALADIN knock-down cells. We conclude that down-regulating ALADIN results in decreased oxidative stress response leading to alteration in steroidogenesis, highlighting our knock-down cell model as an important in-vitro tool for studying the adrenal phenotype in triple A syndrome.