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No description available.

ATP-binding cassette (ABC) transporters use the power of ATP binding and hydrolysis to deliver a wide variety of molecules across membrane bilayers. Crystal structures in the past two decades have provided snapshots of these transporters under various conditions, which revealed conformational changes of transporters upon substrate and ATP binding along the transport pathway. However, understanding of kinetics of substate translocation and the knowledge of transient intermediates along the transport pathway remain primitive, especially for Type II ABC importers. In this thesis work, I employed fluorescence resonance energy transfer (FRET) to study the transport mechanism of BtuCD, a model type II ABC importer that transports vitamin B12. I also exploited the photophysical property of the transport substrate, B12, that quenches the fluorescence of certain fluorophores nearby through FRET, which enables the monitoring of B12 binding and release. Our ensemble FRET data showed the binding of B12 and nucleotide both weaken the interaction between BtuCD and BtuF. Our single-molecule FRET (smFRET) experiments not only revealed stepwise movement of substrate molecule through the transporter in real-time and at the single-molecule level, but also yielded the rates of transition between individual conformational states, which had not been previously characterized in any other transporters. The results showed that ATP hydrolysis, instead of ATP binding, drives the power-stroke for the transport cycle. They also showed two sequential ATP hydrolysis events are required to complete a transport cycle, with the first ATP hydrolysis event delivering B12 into the cavity of BtuCD and the second resetting the BtuCD-F complex for a new cycle of transport.

Yes / Background: The incidence of self-reported premature hair graying (PHG) seems to be on the rise. PHG has a profound impact on the patient's quality of life. It remains an incompletely understood etiology with limited and modest treatment options. Aim: The evaluation of the demographic and clinical profile of patients with premature canities, and exploration of the association of this entity with certain systemic disorders suspected to be related to its etiology. Methods: Seventy-one cases of premature canities (onset noticed by patients before 25 years of age) presenting to an urban skin clinic in Gurugram, India, between September 2012 and September 2015 with this complaint were retrospectively analyzed. The patient records were retrieved that provided details of the onset, duration and pattern of involvement, history, and examination findings (scalp, cutis, and general physical). Since all these patients had been screened for anemia, thyroid disorder, fasting blood glucose, and Vitamin B12 levels at the time of presentation, these parameters were also available for analysis. Results: The mean age at onset of graying was 10.2 ± 3.6 years (range: 5–19 years), with an almost equal gender distribution. The earliest age of onset recorded was 5 years. A positive family history of PHG (at least one of the biological parents or siblings) was obtained in 64 (90.1%) of the cases. The temporal regions of the scalp (35.2%) were most commonly involved followed by the frontal region (18.3%). Hypovitaminosis B12 and hypothyroidism showed significant association with the disorder, whereas anemia, serum ferritin, and fasting blood glucose did not. Conclusion: The age of onset of hair graying can be as low as 5 years. Temporal and frontal areas are the most commonly involved sites. A strong family history, Vitamin B12 deficiency, and hypothyroidism are strongly associated with PHG. Larger case–control studies are mandated for discerning the correlation of these and other risk factors with PHG.

Au cours du développement, les modifications du métabolisme des monocarbones liées à une malnutrition peuvent être délétères autant pour la mère que pour le nouveau-né. De plus, les conséquences à long terme d'une carence en période gestationnelle et périnatale sont mal connues, notamment en ce qui concerne les pathologies cardiaques et hépatiques. Nous avons mis en oeuvre un modèle nutritionnel de rates adultes carencées en donneurs de groupements méthyles (vitamines B12, folates et choline) avant la gestation. Ces micronutriments participent à la régulation de différentes enzymes impliquées dans le métabolisme de l'homocystéine. Afin de se placer dans un contexte de physiopathologie, proche de la situation clinique évaluée, nous avons choisi d'alimenter les rates avec un régime carencé un mois avant la mise en accouplement et de poursuivre ce régime pendant la période d'allaitement. Nous avons évalué les répercussions métaboliques et fonctionnelles du régime sur les tissus myocardique et hépatique, chez le nouveau né à 21 jours. Nous avons étudié l'effet de cette carence en groupements méthyles sur le métabolisme énergétique lipidique et sur la carnitine. Conséquences de la carence au niveau myocardique : Le régime carencé en donneurs de méthyles induit une hypertrophie cardiaque avec une augmentation de l'épaisseur du myocarde et un agrandissement des cardiomyocytes. L'étude protéomique du myocarde et l'analyse des données par bioinformatique identifient PGC-1[alpha], PPAR[alpha] et ERR[alpha] comme principaux déterminants des variations d'expression des protéines du métabolisme oxydatif mitochondrial. Nous avons observé une diminution d'expression de PPAR[alpha] et ERR[alpha] et une inactivation de PGC1[alpha] par hypométhylation et hyperacétylation, en lien avec une diminution d'expression de PRMT1 et de SIRT1 et une augmentation de SAH. Conséquences de la carence au niveau du foie : La carence s'accompagne de l'apparition d'une stéatose hépatique microvésiculaire, avec une élévation des taux tissulaires de lipides et de triglycérides. De plus, nous avons observé une augmentation des marqueurs pro inflammatoires sans augmentation des marqueurs de fibrose. A cet égard, nos résultats ont montré qu'un déficit de synthèse de carnitine, impliquée dans la bêta-oxydation et le stockage des acides gras, jouerait un rôle déterminant dans la pathogenèse de la stéatose chez le nouveau-né. Il existe également une dérégulation du métabolisme oxydatif des acides gras, avec diminution d'activité des complexes I et II de la chaîne respiratoire, qui résulte d'une hypométhylation de PGC1 et d'une diminution d'expression de PPAR[alpha], ER[alpha] et ERR[alpha]. En conclusion, nos résultats montrent que la carence maternelle en donneurs de méthyles, induit des modifications sur la fonction de PGC-1[alpha]. Ces modifications sont associées à des altérations de l'oxydation des acides gras et sur la fonction mitochondriale pendant la période néonatale, ce qui entraîne l'accumulation de lipides dans les tissus myocardique et hépatique. Le lien entre la carence en donneurs de méthyles et l'altération de la méthylation de PGC-1[alpha] modifie les activités des enzymes impliquées dans la méthylation et l'acétylation de PGC-1. Ces enzymes sont aussi liées à des modifications épigénomiques qui modulent la fonction et l'expression des protéines. Nos résultats sont en accord avec les études de population de Barker et al, qui suggèrent que la nutrition maternelle pendant les étapes précoces de la vie est corrélée avec le risque de maladies cardio-vasculaires dans la vie adulte indépendamment des autres facteurs de risque / During development, changes in carbon metabolism related to malnutrition may be deleterious for both the mother and the newborn. In addition, long-term consequences of a methyl deficiency gestational and prenatal are poorly understood. We are particularly interested in studying these effects on the heart and liver. We have used a nutritional model of adult rats deficient in methyl donors (vitamin B12, folate and choline) before pregnancy. To be placed in a context of pathophysiology, close to the clinical situation, we chose to feed the rats with a methyl deficient diet one month before mating and continue this diet during the suckling period. We evaluated the metabolic and functional effects of this diet on myocardial and hepatic tissues, in the newborn pups in 21 days old. We studied the effects of methyl deficient diet on lipid and energy metabolism and carnitine. Consequences of the deficiency at the myocardial: The diet deficient in methyl donors induces cardiac hypertrophy with an increase in myocardial thickness and enlargement of cardiomyocytes. The proteomics analysis of the bioinformatics data identifies PGC-1[alpha], ERR[alpha] and PPAR[alpha] as major determinants of changes in protein expression of mitochondrial oxidative metabolism. We observed a decreased expression of PPAR[alpha] and ERR[alpha] and an inactivation of PGC1[alpha] by hypomethylation and hyperacetylation, in conjunction with a decrease in the expression of PRMT1 and SIRT1 and increased the level of SAH. Consequences of the deficiency at liver: Deficiency is accompanied by the appearance of microvesicular hepatic steatosis, with elevated tissue levels of lipids and triglycerides. Increase of inflammation was observed in this model with no changes in fibrosis score. In this respect, our results showed a deficiency of carnitine synthesis, involved in the beta-oxidation and storage of fatty acids, play a role in the pathogenesis of hepatic steatosis in the newborn. There is also a deregulation of the oxidative metabolism of fatty acids, with decreased activity of complex I and II of the respiratory chain, resulting in hypomethylation of PGC1 and decreased expression of PPAR[alpha], ER[alpha] and ERR[alpha]. In conclusion, our results show that maternal deprivation in methyl donors impaired the function of PGC-1[alpha]. These changes are associated with alterations in fatty acid oxidation and mitochondrial function during the neonatal period, with lipid accumulation in myocardial tissue and liver. The link between the methyl donor deficiency and impaired methylation of PGC-1[alpha] alters the activities of enzymes involved in methylation and acetylation of PGC-1[alpha]. These enzymes are also associated with epigenetic changes and the function and gene expression. Our results are consistent with population studies by Barker and colleagues, who suggest that maternal nutrition during early stages of life is correlated with the risk of cardiovascular disease in adult, independent of other risk factors

A transcobalamina II (TCII) é a única proteína que leva a cobalamina (Cbl) para dentro das células. A TCII ligada a Cbl é denominada Holo-TC. Polimorfismos no gene TC2 podem alterar tanto a função como a concentração de Holo-TC. Os objetivos deste estudo foram avaliar se o parâmetro Holo-TC é um bom marcador de deficiência de Cbl; avaliar o efeito dos polimorfismos TC2 P259R, I23V e Q234R nos marcadores da deficiência da Cbl; verificar os fatores de predição para os valores de tHcy, SAM/SAH, MMA e Holo-TC nas gestantes e seus recém- nascidos. A Holo-TC não foi bom marcador para discriminar as gestantes com e sem deficiência de Cbl, diferente do encontrado no grupo de recém nascidos. Os genótipos matemos para os polimorfismos TC2 P259R e I23V não foram associados com as alterações nos valores matemos de tHcy, MMA e Holo-TC. Os neonatos portadores dos genótipos PR+RR apresentaram menores valores da razão SAM/SAH e maiores de MMA. Os neonatos com genótipos 23V+23VV apresentaram menores valores de SAM e maiores valores de tHcy. A combinação dos genótipos IV+VV/PR+RR no grupo de gestantes foi associada a menores valores de SAM. Já os neonatos com a mesma combinação de genótipos apresentaram menores valores de SAM e da razão SAM/SAH. O folato sérico foi o melhor fator de predição para a variação da tHcy materna, e a Cbl para os valores de Holo-TC, e finalmente a creatinina e a Cbl foram os fatores de predição para os valores de MMA. A Cbl e o folato foram os preditores para a tHcy neonatal quando foi utilizado apenas as variáveis independentes maternas no modelo de regressão linear múltipla. No entanto, quando as variáveis independentes foram as neonatais, Cbl, folato sérico e SAM/SAH neonatais foram as selecionadas para explicar os valores de tHcy neonatal. Para os modelos neonatais de MMA, a Cbl materna foi a única selecionada quando o modelo foi feito com variáveis independentes maternas. E noutro modelo da MMA neonatal, a Cbl e o genótipo PR + RR neonatal explicaram a variabilidade do MMA neonatal. Para a razão SAM/SAH neonatal, foram o folato sérico e o genótipo RR maternos as variáveis selecionadas quando só foram colocadas as variáveis independentes maternas no modelo. E finalmente, a tHcy e genótipos PR + RR foram as variáveis neonatais selecionadas no modelo de regressão linear múltipla para a razão SAM/SAH neonatal. Podemos concluir que os genótipos para os polimorfismos TC2 P259R e I23V não estão associados a variabilidade dos valores matemos dos metabólitos, no entanto, no recém nascido esta associação foi evidenciada. / Transcobalamin II (TCII) is the only protein that can take cobalamin (Cbl) into cells. When TCII is bound to the Cbl it is called Holo-TC. Polymorphisms inTC2 gene can alter both the function and the concentration of Holo-TC. The objective of this study was to evaluate whether the parameter Holo-TC is a good Cbl deficiency marker; to evaluate the effect of the polymorphisms TC2 P259R, I23V and Q234R in the Cbl deficiency markers; to verify the prediction factors for the values of tHcy, SAM/S~ MMA and Holo-TC in pregnant women and their neonates. Holo-TC has proved not be a good marker for discriminating pregnant women with Cbl deficiency from those without Cbl deficiency, unlike what was seen in the neonatal group. Maternal genotypes for polymorphisms TC2 P259R and I23 V were not related with the alterations ofmaternal values of tHcy, MMA and Holo-TC. The neonates presenting genotypes PR+RR showed lower SAM/SAH ratio values and higher MMA values. The neonates with genotypes 23V+23VV presented lower SAM values and higher tHcy values. The combination of genotypes IV+VV/PR+RR in the group of pregnant women was related with lower SAM values. On the other hand, the neonates presenting the same combination of genotypes presented lower SAM values and SAM/SAH ratio values. Se rum folate was the best predictor for the variation of the maternal tHcy, and Cbl for the Holo-TC values. The creatinine and the Cbl were the predictors for the values of MMA. Cbl and folate were the predictors for the neonatal tHcy when only the maternal independent variables were used in the multiple linear regression model. However, when the neonatal independent variables were used, Cbl, serum folate and SAM/SAH of neonates were selected to explain the neonatal tHcy values. For the neonatal models of MMA, only the maternal Cbl was selected for the model with maternal independent variables. In another neonatal MMA model, Cbl and neonatal PR + RR genotype explained the variability of the neonatal MMA. For the neonatal SAM/SAH ratio, serum folate and maternal RR genotype were the variables selected when only the maternal independent variables were used in the model. Finally, tHcy and genotypes PR + RR were the neonatal variables selected in the multiple linear regression model for the neonatal SAM/SAH ratio. We have concluded that the genotypes for the polymorphisms TC2 P25 9R and I23 V are not related to the variability of the maternal values of the metabolites; however, this relation is clear when evaluating the values observed in their newborn babies.

Objetivo Examinar a correlação entre fatores dietéticos, obtidos por questionário de freqüência alimentar (QFA) validado, e concentrações séricas ou plasmáticas de homocisteína (hcy), ácido fólico, vitaminas B12 e B6 em mulheres de São Paulo. População e métodos Foram analisados os dados dietéticos de 1.434 mulheres de 21 a 65 anos de um estudo caso-controle sobre consumo alimentar e lesões neoplásicas do colo uterino realizado em três hospitais públicos da cidade de São Paulo, excluindo-se os casos de câncer invasivo. Todas participantes tiveram sua ingestão alimentar usual avaliada por entrevista, usando um QFA, e forneceram amostras sangüíneas em jejum para separação de plasma e soro. Concentrações séricas de ácido fólico e vitamina B12 séricos foram analisadas por técnica de fluoroimunoensaio, enquanto concentrações plasmáticas de hcy e vitamina B6 foram analisadas por Cromatografia Líquida de Alta Performance em fase reversa. Correlações entre ingestão estimada de nutrientes, ajustados pelas calorias totais, e alimentos com as variáveis bioquímicas foram avaliadas em modelos de regressão linear múltiplos, após ajuste para co-variáveis, tais como idade, Índice de Massa Corporal (IMC), estilo de vida (incluindo tabagismo), morbidade ginecológica pregressa ou atual, história obstétrica e uso de anticoncepcional oral. Resultados Embora apenas 6,2% das participantes do estudo tenham apresentado concentrações séricas de ácido fólico abaixo do valor de referência (7 nmol/L), 45,7% e em 97,1% tiveram um consumo estimado de folato inferior a 180 ug/dia e 400 ug/dia, respectivamente. Modelos de regressão múltiplos mostraram correlação positiva entre ácido fólico sérico e ingestão estimada de proteína, ferro, folato, vitaminas B1, B3, B6, A, C e frutas/sucos cítricos e de vegetais verdes, e correlação inversa entre ácido fólico sérico e consumo estimado de gorduras, doces e leite e derivados. Resultados similares foram obtidos após ajuste adicional para fibra da dieta, exceto com consumo de folato e de vegetais verdes, que perderam a significância estatística como preditores independentes das concentrações séricas de ácido fólico. Concentrações séricas de vitamina B12 abaixo do ponto de corte de 148 pmol/L foram observadas em 11,0% da amostra; a maioria delas (70,4%) apresentou ingestão estimada de vitamina B12 igual ou superior à recomendação (2 ug/dia). As concentrações séricas de vitamina B12 foram positivamente correlacionadas com consumo estimado de produtos lácteos e das vitaminas B2 e B12. A ingestão de fibra, vitamina E e leguminosas foi inversamente correlacionada com as concentrações séricas de vitamina B12. Ingestão de vitamina B6 abaixo das recomendações de 1,3 mg/dia (≤50 anos) e 1,5 mg/dia (>50 anos) foi observada em 49% das participantes. Nenhuma correlação foi encontrada entre dados da dieta e concentrações plasmáticas de vitamina B6. As concentrações plasmáticas de hcy foram positivamente correlacionadas com o consumo estimado de carboidratos e doces, e inversamente correlacionadas com o consumo estimado de proteína, colesterol, ferro, zinco de origem animal, vitaminas A, B2, B12 e B6, e pescados. Entretanto, essas correlações perderam a significância após ajuste adicional por proteína da dieta, um dos mais fortes preditores das concentrações plasmáticas de hcy. Conclusão Nutrientes e alimentos selecionados da dieta mostraram-se preditores independentes das concentrações séricas de ácido fólico e de vitamina B12, indicando as principais fontes alimentares desses nutrientes nesta população e em outras similares. A forte correlação negativa entre concentração plasmática de Hcy e proteína da dieta sugere base para o planejamento de futuras intervenções nutricionais. Nenhuma correlação foi observada entre concentração plasmática de vitamina B6 e fatores dietéticos estimados. / Objective To examine whether measurements of dietary intakes, obtained with a validated quantitative food frequency questionnaire (FFQ), correlated with serum or plasma levels of folic acid, vitamins B12 and B6 and homocystein (hcy) measured in low-income women living in São Paulo, Brazil. Population and methods We analyzed dietary data from 1434 women aged 21-65 years enrolled in a case-control study of diet and cervical cancer carried out in three public hospitals of São Paulo. Data for women with invasive cervical cancer were excluded. All participants had their usual dietary intake assessed by interview, using a validated FFQ, and provided a fasting blood sample for serum and plasma separation. Serum concentrations of folic acid and vitamin B12 were measured by fluorimmunoassay, while serum levels of vitamin B6 and plasma levels of hcy were measured by reversed-phase high performance liquid chromatography. Correlations between estimates of food and energy-adjusted nutrient intakes and levels of folic acid, vitamins B12 and B6 and hcy were assessed using multiple linear regression models, adjusted for covariates such as age, body mass index, lifestyle (including smoking), past and current gynecologic morbidity and obstetric history, and use of oral contraceptives. Results Although only 6.2% of the study participants had serum folic acid levels below the reference value of 7 nmol/L, 45.7% and 97.1% had a dietary intake of folic acid estimated to be less than 180 g/day and 400 g/day, respectively. Multiple linear models showed serum folic acid levels to be positively correlated with the estimated intake of protein, iron, folate, vitamins B1, B3, B6, A and C, citrus fruits and juices and green vegetables, and negatively correlated with the estimated intake of fat, sweets and dairy products. Similar results were obtained after a further adjustment for fiber intake in the model, except for the estimated intake of folic acid and green vegetables, which lost their statistical significance as independent predictors of serum folic acid levels. Serum levels of vitamin B12 below the cut-off point of 148 pmol/L were found in 11.0% of study participants; most of them (70.4%) had their vitamin B12 intake estimated to be equal or greater than the reference value of 2 g/day. Serum levels of vitamin B12 were positively correlated with the estimated intake of dairy products and vitamins B2 and B12. The estimated intakes of fiber, vitamin E and beans were negatively correlated with serum levels of vitamin B12. Dietary vitamin B6 was estimated to be below the recommended levels of 1.3 mg/day (age  50 years) or 1.5 mg/day (age > 50 years) in 49.0% of study participants. No correlation was found between estimated intakes of foods and nutrients and plasma levels of vitamin B6. Hcy concentrations were positively correlated with the estimated intake of carbohydrates and sweets, and negatively correlated with the estimated intake of protein, cholesterol, iron, zinc of animal origin, vitamins A, B2, B12 and B6 and fishes. However, these correlations were no longer significant after additional adjustment for dietary protein, the strongest predictor of hcy plasma levels. Conclusion The estimated dietary intakes of selected foods and nutrients were shown to be independent predictors of measured serum levels of folic acid and vitamin B12, providing a basis for indentifying the main dietary sources of these nutrients in this and similar populations. The strong negative correlation between plasma levels of hcy and dietary protein provides a basis for future nutritional interventions. No correlation was found between plasma concentrations of vitamin B6 and estimated dietary intakes.

Nous avons étudié les aspects biochimiques, enzymologiques et génétiques des voies de la méthylation sur les foies foetaux issus d'abortum pour AFTN et témoins. Nous avons mis en évidence un déficit de la vitamine B12 et de la SAM et une baisse des activités MTR et MTHFR dans les tissus AFTN. Ces résultats permettent d'établir qu'une supplémentation en B12 devrait être associée à la supplémentation en folates réalisée en début de grossesse afin de prévenir la survenue de ces AFTN. Nous avons aussi étudié les interactions entre MTR et MMACHC en utilisant des lignées cellulaires de patients porteurs de déficits en MTR (cblG, variant-cblG) et en MMACHC (cblC). Cette étude suggère un rôle régulateur de la MTR dans le métabolisme intracellulaire de la CNCbl, par l'épissage de MTR de deux transcrits codant pour l'enzyme fonctionnelle de taille attendue et une protéine tronquée non fonctionnelle, respectivement / We studied the methylation pathways in liver tissue from fetal NTDs and controls. We identified a vitamin B12 and SAM deficiency and also decreased activities of MTR and MTHFR in NTDs tissue. These results provide evidence that vitamin B12 supplementation should be associated with folate supplementation in early pregnancy in order to prevent the occurrence of these NTDs. We also studied the interactions of MTR with MMACHC by using cell lines patients with MTR and MMACHC deficiency. This study suggests a regulatory role of MTR in the intracellular CNCbl metabolism by splicing of two MTR transcripts encoding the functional enzyme of the expected size and a truncated non-functional protein, respectively

La chlordécone (cld) de formule brute c10cl10o est un pesticide organochloré classé parmi les polluants organiques persistants (pop) par la convention de stockholm en 2009. Ce composé a été appliqué dans les soles bananières des antilles françaisede 1950 à 1993 : ce qui a conduit à une pollution généralisée de l’environnement dans les zones de production de banane. De plus il a été montré une imprégnation généralisée de la biosphère, avec un impact sanitaire décrit dans de nombreuses publications. Il est connu que la cld a une longue persistance dans les sols, conduisant à une contamination des eaux. Aussi, dans les zones polluées de la guadeloupe et de la martinique, les usines de production d'eau ont été équipées de filtres à charbon actif (ca). Cependant, après le traitement, le ca est contaminé, il est alors nécessaire de le régénérer.Un des axes de recherche de l’équipe covachim-m2e « connaissance et valorisation-chimie des matériaux environnement, énergie» est la fabrication de ca préparés à partir des ressources naturelles tropicales telle que la bagasse pour à la fois valoriser des quantités élevées de résidus lignocellulosiques disponibles localement, à un coût modéré, mais surtout pour une adsorption efficace de la cld, afin d’obtenir les informations par le mécanisme d’adsorption de la vb12 sur le ca. Un matériau hybride (mh) composé de ca de la vitamine b12 ou cobalamine (vb12) a été préparé à l’aide d’une fixation non-covalente, par adsorption de manière à préserver l’activité de déchloruration de la vb12.Il est montré que la vb12 réduite par le zinc zérovalent, est capable de dégrader cld, en accord avec les travaux de schrauzer publiés en 1978, montrant que la vb12, réduite par l’acétoine ou bien le borohydrure de sodium était capable dégrader la cld. Les intermédiaires de dégradation produits, ont été caractérisés par chromatographie en phase gazeuse couplée à un spectromètre de masse (cg-sm). Les cinétiques et isothermes d'adsorption de la vb12 sur ca ont été modélisées à l’aide de différents modèles mathématiques ceci permet de comprendre les interactions physico-chimiques mis en jeu entre les deux composants du matériau hybride lors du processus d’adsorption. Il a été révélé que la dynamique d’adsorption est bien décrite par le modèle du pseudo-second ordre. La fixation de la vb12 est plus importante sur le ca bagp1.5, préparé par activation de la bagasse par l’acide phosphorique, avec une valeur capacité d'adsorption maximale déduite du modèle de langmuir de 422 mg.g-1. L’adsorption est favorisée à haute température, et optimale à un ph de 6. En outre, afin d'étudier la stabilité du matériau hybride élaboré, la désorption de la vb12 adsorbée sur la bagp1.5 a également été suivie en milieu aqueux et dans l’éthanol. Le mh ainsi préparé a été caractérisé en utilisant différentes techniques, la méthode de boehm, la microscopie à balayage, la résonance raman, la spectrométrie de fluorescence x, la spectroscopie de photo-électron x, l’infra-rouge à transformée de fourieret aussi par adsorption d’azote.L’objectif de ce travail est d’optimiser la quantification de la cld et de ses intermédiaires de dégradation par une méthode en cg-sm et de mettre au point une méthode de dégradation de la cld en vue de la régénération des ca.Nos travaux ont montré que la vitesse de disparition de la cld est plus élevée pour le matériau hybride, que pour le charbon seul ou la vb12 seule. Les réactions de dégradation de la cld par la vb12 ont montré dans des conditions anaérobies, l’apparition de 3 intermédiaires dérivés de la cld. Ces intermédiaires ont été caractérisés en cg-ms à savoir la mono et dihydrochlordécone, ainsi qu’un dérivé pentachloroindène. / Chlordecone (cld) with an empirical formula c10cl10o is an organochlorine pesticide classified among the persistent organic pollutants (pops) by the stockholm convention in 2009. This compound was applied to banana plantation in the french west indies from 1950 to 1993: resulting to widespread environmental pollution in banana production areas. In addition it has been shown a generalized pollution of the biosphere, with a health impact described in many publications. It is known that cld has a long persistence in soils, leading to water contamination. Consequently, in the polluted areas of guadeloupe and martinique, the water production plants were equipped with activated carbon filters (ac). However, after water treatment, the ac is contaminated, it is then necessary to regenerate it.One of the research areas of the covachim-m2e team is the elaboration of ac from tropical natural resources such as bagasse to both add value the high amounts of lignocellulosic residues locally available at moderate cost, but as well especially for efficient adsorption of the cld. A hybrid material composed of activated carbon (ac) and vitamin b12 (vb12), known as cobalamin was prepared using a non-covalent attachment, by adsorption to preserve the dechlorination activity of vb12.It is shown that vitamin b12 reduced zerovalent zinc is able to degrade cld, in agreement with the work of schrauzer published in 1978, showing that vitamin b12, reduced by acetoin or sodium borohydride capable of degrading the cld. The intermediate degradation products, were characterized by gas chromatography coupled with mass spectrometric detection (gc-ms) to get right one vb12 adsorption mechanism. To get insight on vb12 adsorption mechanism, kinetic and adsorption isotherms of vb12 on ac were modeled using various mathematical models. It allows to understand the physical and chemical interactions involved between the two components of the hybrid material during the adsorption process. It was revealed that the adsorption dynamics is well described by the model of the pseudo-second order and brouers-sotolongo. Amount of the vb12 fixed on is more important on the bagp1.5 ac prepared by activation of the bagasse by the phosphoric acid, as a maximum adsorption capacity value derived from the langmuir model 422 mg.g-1. Adsorption is favored at high temperature, and at optimum value of ph 6. Furthermore, in order to study the stability of the prepared hybrid material, desorption of the adsorbed from bagp1.5 has also been followed in an aqueous medium and in absolute ethanol. Mh thus prepared was characterized using different technique, the method of boehm, scanning electron microscopy, raman resonance, and x-ray fluorescence spectrometry and x-ray photoelectron, infrared transform fourier spectroscopies and also by nitrogen adsorption.The objective of this work is to optimize the quantification of the cld and its intermeodiates by a gas chromatography method coupled with a mass spectrometer (gc-ms) and to develop a method of degradation of the cld for the regeneration of activated carbon.Our work has shown that the rate of disappearance of cld is higher for the hybrid material than vb12 alone. The degradation reactions of cld by vb12 under anaerobic conditions showed the appearance of 3 cld intermediates: mono and dihydrochlordecone and a pentachloroindène derivative that were characterized by gc-ms.

A transcobalamina II (TCII) é a única proteína que leva a cobalamina (Cbl) para dentro das células. A TCII ligada a Cbl é denominada Holo-TC. Polimorfismos no gene TC2 podem alterar tanto a função como a concentração de Holo-TC. Os objetivos deste estudo foram avaliar se o parâmetro Holo-TC é um bom marcador de deficiência de Cbl; avaliar o efeito dos polimorfismos TC2 P259R, I23V e Q234R nos marcadores da deficiência da Cbl; verificar os fatores de predição para os valores de tHcy, SAM/SAH, MMA e Holo-TC nas gestantes e seus recém- nascidos. A Holo-TC não foi bom marcador para discriminar as gestantes com e sem deficiência de Cbl, diferente do encontrado no grupo de recém nascidos. Os genótipos matemos para os polimorfismos TC2 P259R e I23V não foram associados com as alterações nos valores matemos de tHcy, MMA e Holo-TC. Os neonatos portadores dos genótipos PR+RR apresentaram menores valores da razão SAM/SAH e maiores de MMA. Os neonatos com genótipos 23V+23VV apresentaram menores valores de SAM e maiores valores de tHcy. A combinação dos genótipos IV+VV/PR+RR no grupo de gestantes foi associada a menores valores de SAM. Já os neonatos com a mesma combinação de genótipos apresentaram menores valores de SAM e da razão SAM/SAH. O folato sérico foi o melhor fator de predição para a variação da tHcy materna, e a Cbl para os valores de Holo-TC, e finalmente a creatinina e a Cbl foram os fatores de predição para os valores de MMA. A Cbl e o folato foram os preditores para a tHcy neonatal quando foi utilizado apenas as variáveis independentes maternas no modelo de regressão linear múltipla. No entanto, quando as variáveis independentes foram as neonatais, Cbl, folato sérico e SAM/SAH neonatais foram as selecionadas para explicar os valores de tHcy neonatal. Para os modelos neonatais de MMA, a Cbl materna foi a única selecionada quando o modelo foi feito com variáveis independentes maternas. E noutro modelo da MMA neonatal, a Cbl e o genótipo PR + RR neonatal explicaram a variabilidade do MMA neonatal. Para a razão SAM/SAH neonatal, foram o folato sérico e o genótipo RR maternos as variáveis selecionadas quando só foram colocadas as variáveis independentes maternas no modelo. E finalmente, a tHcy e genótipos PR + RR foram as variáveis neonatais selecionadas no modelo de regressão linear múltipla para a razão SAM/SAH neonatal. Podemos concluir que os genótipos para os polimorfismos TC2 P259R e I23V não estão associados a variabilidade dos valores matemos dos metabólitos, no entanto, no recém nascido esta associação foi evidenciada. / Transcobalamin II (TCII) is the only protein that can take cobalamin (Cbl) into cells. When TCII is bound to the Cbl it is called Holo-TC. Polymorphisms inTC2 gene can alter both the function and the concentration of Holo-TC. The objective of this study was to evaluate whether the parameter Holo-TC is a good Cbl deficiency marker; to evaluate the effect of the polymorphisms TC2 P259R, I23V and Q234R in the Cbl deficiency markers; to verify the prediction factors for the values of tHcy, SAM/S~ MMA and Holo-TC in pregnant women and their neonates. Holo-TC has proved not be a good marker for discriminating pregnant women with Cbl deficiency from those without Cbl deficiency, unlike what was seen in the neonatal group. Maternal genotypes for polymorphisms TC2 P259R and I23 V were not related with the alterations ofmaternal values of tHcy, MMA and Holo-TC. The neonates presenting genotypes PR+RR showed lower SAM/SAH ratio values and higher MMA values. The neonates with genotypes 23V+23VV presented lower SAM values and higher tHcy values. The combination of genotypes IV+VV/PR+RR in the group of pregnant women was related with lower SAM values. On the other hand, the neonates presenting the same combination of genotypes presented lower SAM values and SAM/SAH ratio values. Se rum folate was the best predictor for the variation of the maternal tHcy, and Cbl for the Holo-TC values. The creatinine and the Cbl were the predictors for the values of MMA. Cbl and folate were the predictors for the neonatal tHcy when only the maternal independent variables were used in the multiple linear regression model. However, when the neonatal independent variables were used, Cbl, serum folate and SAM/SAH of neonates were selected to explain the neonatal tHcy values. For the neonatal models of MMA, only the maternal Cbl was selected for the model with maternal independent variables. In another neonatal MMA model, Cbl and neonatal PR + RR genotype explained the variability of the neonatal MMA. For the neonatal SAM/SAH ratio, serum folate and maternal RR genotype were the variables selected when only the maternal independent variables were used in the model. Finally, tHcy and genotypes PR + RR were the neonatal variables selected in the multiple linear regression model for the neonatal SAM/SAH ratio. We have concluded that the genotypes for the polymorphisms TC2 P25 9R and I23 V are not related to the variability of the maternal values of the metabolites; however, this relation is clear when evaluating the values observed in their newborn babies.