Manganese-deficient Streptococcus sanguinis mutants exhibit a dramatic decrease in virulence for infective endocarditis and in aerobic growth in manganese-limited media. Loss of activity of a manganese-dependent, oxygen-dependent ribonucleotide reductase (RNR) could explain the decrease in virulence. When the genes encoding this RNR are deleted, there is no growth of the mutant in aerobic broth culture or in an animal model. Testing the contribution of the aerobic RNR to the phenotype of a manganese transporter mutant, a heterologous class II RNR from Lactobacillus leichmannii called NrdJ that requires B12 rather than manganese as a cofactor was previously introduced into an RNR mutant of S. sanguinis. Aerobic growth was only partially restored. Currently, we sought to improve NrdJ-dependent growth by (i) amending the medium to increase cellular levels of B12; (ii) characterizing a spontaneous mutant of the NrdJ-complemented strain with improved aerobic growth; and (iii) altering this strain through further genetic manipulation.

Orientadores: Nelci Fenalti Höehr, Joyce Maria Annichino-Bizzacchi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-24T12:13:12Z (GMT). No. of bitstreams: 1 Barnabe_Aline_D.pdf: 1712567 bytes, checksum: 647e2ea59dbddb21e153a8e6ceae61cc (MD5) Previous issue date: 2014 / Resumo: Folato, vitamina B12 e ferro são nutrientes essenciais, cujas deficiências afetam indivíduos em todas as faixas etárias, sendo consideradas um problema de Saúde Pública no mundo. Níveis reduzidos de folato e vitamina B12 podem estar associados com níveis elevados de homocisteína (Hcy), e que eventualmente resultam em complicações. Entretanto, no Brasil, poucos estudos avaliaram a prevalência dessas deficiências, principalmente de folato e vitamina B12, após a fortificação de farinhas com ácido fólico e ferro. Os objetivos do presente estudo foram: avaliar a prevalência das deficiências de folato, vitamina B12 e ferro em idosos, crianças, gestantes e lactantes após a fortificação de farinhas com ácido fólico e ferro adotado pela ANVISA em 2004; e investigar a contribuição de polimorfismos genéticos sobre os níveis de folato, vitamina B12 e Hcy nestes indivíduos. Os indivíduos foram recrutados em Centros de Saúde da cidade de Campinas entre 2006 a 2007. No total, 719 indivíduos incluindo, 262 idosos, 106 crianças, 291 gestantes e 60 lactantes foram incluídos. As concentrações destes nutrientes foram mensuradas por eletroquimioluminescência; a dosagem de Hcy foi realizada por cromatografia líquida de alta eficiência (CLAE); e os polimorfismos foram investigados por PCR-RFLP. Os resultados mostraram que a prevalência das deficiências de folato, vitamina B12 e ferro no grupo total de indivíduos foram de 0,3%, 5,3% e 12,6%, respectivamente. Praticamente não se observou a deficiência de folato, presente apenas em um idoso e uma gestante, enquanto que a deficiência de vitamina B12 foi prevalente em gestantes (8,9%) e idosos (4,2%). Além disso, a deficiência de ferro e anemia ferropriva foram prevalentes em crianças (9,9% e 4,9%, respectivamente), e gestantes (25,1% e 5,5%, respectivamente). A hiperhomocisteinemia esteve presente principalmente em idosos (34,3%). Com relação aos polimorfismos, apenas as gestantes carreadoras dos alelos CT+TT do polimorfismo no gene MTHFR (C677T) mostraram níveis reduzidos de folato (p=0,030). Através da análise múltipla, observamos que os níveis de Hcy foram determinados principalmente pelo folato (p<0,001), vitamina B12 (p<0,001), gênero (p<0,001) e idade (p<0,001) em idosos; vitamina B12 (p= 0,011) em crianças e folato (p=0,002) em gestantes. Nossos resultados demonstraram que na população avaliada, após 2 anos do início da fortificação de farinhas com ácido fólico e ferro, a deficiência de folato é praticamente inexistente, ao contrário da deficiência de ferro e de vitamina B12. A elevada prevalência da deficiência de vitamina B12 em idosos e gestantes deve ser valorizada na prática, devido ao risco de complicações. O mesmo deve ser observado em relação à deficiência de ferro, prevalente em crianças e gestantes. Portanto, medidas como suplementação e a dosagem desses nutrientes, para grupos populacionais de risco, devem ser implementados em políticas de Saúde Pública. Além disso, a hiperhomocisteinemia observada em idosos pode ser um fator de risco ou um marcador de doença arterial, que é comum nesses indivíduos / Abstract: Folate, vitamin B-12 and iron are essential nutrients, whose deficiencies are considerable public health problems worldwide, affecting all age groups. Low levels of folato and vitamin B12 have been associated with high concentrations of homocysteine (Hcy) and can lead to complications. In Brazil, a few studies evaluated the prevalence of these nutrients, especially, folate and vitamin B12, post acid folic and iron fortification era. The aim of this study was to assess folate, vitamin B12 and iron deficiencies in distinct Brazilian populations including elderly, children, pregnant and lactating women, after the initiation of folic acid and iron fortification by Brazilian authorities. We also investigated the contribution of polymorphisms on folate, vitamin B12 and Hcy levels in these individuals. Folate, vitamin B12 and ferritin levels were measured by chemiluminescence immunoassays, and Hcy levels were determined by high-performance liquid chromatography. Genotype analyses of RFC1 A80G, GCPII C1561T and MTHFR C677T polymorphisms were performed by PCR-RFLP. The individuals were recruited from primary care centers in Campinas ¿ Brazil, between 2006 - 2007. In total 719 individuals, including elderly (262), children (106), pregnant women (291) and lactating women (60) were included. The overall prevalence of low folate, vitamin B-12 and iron status was 0.3%, 5.3% and 12.6%, respectively. Folate deficiency was practically inexistent and was observed only in elderly (n=1) and pregnant women (n=1), whereas vitamin B12 deficiency was frequent in pregnant women (8.9%) and elderly (4.2%). Moreover, iron deficiency and iron deficiency anemia were prevalent in children (9.9% and 4.9%, respectively) and pregnant women (25.1% and 5.5%, respectively). Plasma Hcy concentrations were significantly higher in the elderly (34.3%). Pregnant women carrying the MTHFR 677T allele (CT+TT) showed lower serum folate levels (p=0.030), but none of the polymorphisms investigated in this study affected folate, vitamin B12 and Hcy levels in elderly, children and lactating women. After a multivariate analysis, Hcy levels were predicted by variables such as folate (p<0.001), vitamin B12 (p<0.001), gender (p<0.001) and age (p<0.001) in elderly; vitamin B12 (p= 0.011) in children; and folate (p = 0.002) in pregnant women. Our results demonstrated that folate deficiency is practically inexistent in this population, two years after the initiation of folic acid fortification, in contrast to vitamin B12 and iron deficiency. The high prevalence of vitamin B12 deficiency in elderly and pregnant women is relevant due to health complications. Supplementation and measure of nutrients in some groups of the population should be indicated by Public Health¿s policies. Furthermore, hiperhomocysteinemia in elderly can be a risk factor or a marker of arterial disease, which is common in these individuals / Doutorado / Ciencias Biomedicas / Doutora em Ciências Médicas

No description available.

No description available.

<p>Small molecule metabolites have important and diverse roles in every major cellular function. To study the activities of metabolites and the biological processes in which they are involved, it is important to be able to detect their levels within cells. Technologies that measure the concentrations of small molecules within the context of living, growing cells are highly advantageous but are challenging to produce. In this thesis, a novel class of intracellular small molecule sensors is produced, characterized and applied to address novel and relevant research questions. These sensors detect a specific target molecule within bacterial cells using RNA regulatory elements known as riboswitches and one of many possible reporter proteins. In addition to a project that yielded new methodology to create custom riboswitches, two projects that assess the capabilities of sensors that detect an active form of vitamin B12 are described. These projects present an abundance of data that provide novel insights into the transport and metabolism of vitamin B12 in <em>E. coli</em> cells. Overall, the results presented indicate that riboswitch-based sensors represent valuable and unique tools for the study of microbial biology. The thesis is concluded with a discussion that describes design strategies and several exciting potential applications for future riboswitch sensors.</p> / Doctor of Philosophy (PhD)

Background: Folate and vitamin B12 have interdependent metabolic functions that are essential for neonate growth outcomes (i.e. birth weight) based on studies from India. The objective of this research was to evaluate the association of maternal folate and vitamin B12 concentrations with neonate birth weight in South Asian (SA) and white European (WE) populations. Methods: In this cross-sectional analysis of prospective cohort studies, maternal and neonatal data were collected during the second trimester from 3758 mother-child dyads living in Canada. Maternal diet and supplement use were assessed using a validated food frequency questionnaire. Biochemical indicators were analyzed in a subset of SA mothers. Birth weight was measured within 72 hours of delivery. All regression analyses were performed unadjusted and with adjustment for identified covariates. Results: Maternal folate and vitamin B12 (dietary, supplemental and total) were not associated with neonate birth weight in SA and WE pregnant women. Higher consumption of milk products by SA women was associated with higher birth weight (β=0.06; p=0.01), whereas higher consumption of egg by WE women was associated with lower birth weight (β=-0.19; p<0.01). Folate and vitamin B12 deficiency in the SA subgroup was 13.7% and 17.8%, respectively. Maternal serum vitamin B12 status was inversely associated with birth weight (β=-0.16; p=0.03). Conclusions: Folate and vitamin B12 may be proxies for poor nutritional status. Therefore, folate and vitamin B12 may have an association with neonate birth weight in a less developed area (i.e. India) rather than in a highly developed area (i.e. Canada). Highly developed countries have an adequate intake of folate and vitamin B12 and thus a higher nutritional baseline status. These findings complement current research on folate and vitamin B12 concentrations with birth weight in well-nourished populations. / Thesis / Master of Science (MSc) / Infant birth weight is an indicator of health and disease risk in adult life. The mother’s vitamin intake can influence the weight of the infant. This research aimed to study whether the mother’s folate and vitamin B12 status is related to infant birth weight. Dietary and supplemental data along with blood samples from South Asian and white European pregnant women living in Canada were collected during the second trimester. The mother’s dietary, supplemental and total folate and vitamin B12 intakes were not related to infant birth weight. In South Asian mothers, higher milk intake was related to higher birth weight and in white Europeans, higher egg intake was related to lower infant birth weight. Higher vitamin B12 in the blood was related to lower infant birth weight in South Asians. More research is needed to determine the relationship between folate and vitamin B12 with infant birth weight.

-- Thèse fournie sans page de titre --Afin de mieux comprendre la physiopathologie des causes gastriques de malabsorption de la vitamine B12, nous nous sommes intéressés au déficit congénital en facteur intrinsèque, une maladie rare caractérisée par une diminution de la sécrétion de facteur intrinsèque (FI) fonctionnel dans le suc gastrique. Dans cette étude, nous rapportons cinq cas porteurs hétérozygotes du variant GIF c.290T>C (p.M97T) et deux cas porteurs hétérozygotes du variant GIF c.435_437delGAA (p.K145_N146delinsN). L'étude fonctionnelle des FI recombinants mutés produits par mutagenèse dirigée a mis en évidence une diminution de l'affinité du FI p.K145_N146delinsN pour la vitamine B12 n'expliquant toutefois pas totalement le phénotype observé chez les sujets. Par ailleurs, une association a été récemment décrite entre le polymorphisme rs601338, c.461 G>A du gène FUT2, codant pour une [alpha]1,2-fucosyltransférase, et les taux plasmatiques de vitamine B12. Afin de compléter notre étude, nous avons évalué l'influence du polymorphisme FUT2 c.461 G>A sur les taux de vitamine B12, de folates et d'homocystéine dans les populations Européennes et Africaines chez 1466 sujets. Notre étude démontre un effet du polymorphisme FUT2 c.461 G>A sur les taux plasmatiques de vitamine B12 et de folates indépendamment de l'âge, du sexe et de l'origine géographique. En conclusion, nos résultats démontrent que le gène du FI (GIF) n'est pas le seul gène impliqué dans la physiopathologie du déficit congénital en facteur intrinsèque. L'étude des malabsorptions d'origine gastrique de la vitamine B12 passe par une approche polygénique dans laquelle le gène FUT2 occupe une place importante / There are multiple causes of gastric vitamin B12 malabsorption. To get a better understanding of their physiopathology, we are interested in inherited gastric intrinsic factor (GIF) deficiency, a vitamin B12 absorption defect characterized by GIF impaired activity. In this study, we report five cases heterozygous carriers of the variant GIF c.290T>C (p.M97T) and two cases heterozygous carriers of the variant GIF c.435_437delGAA (p.K145_N146delinsN). The study of recombinant mutated GIF produced by site-directed mutagenesis evidenced a reduced affinity for vitamin B12 in the case of GIF p.K145_N146delinsN which does not explain fully the phenotypes observed in our subjects. Recently, an association was described between the FUT2 polymorphism rs601338, c.461 G>A, coding for a fucosyltransferase, and plasma levels of vitamin B12. To complete our study, we assessed the influence of FUT2 c.461 G>A polymorphism on vitamin B12, folate and homocysteine in European and African populations in 1466 subjects. Our study demonstrate a clear effect of FUT2 c.461 G>A polymorphism on both plasma levels of vitamin B12 and folate, regardless of age, gender, and geographic origin. In conclusion, our results demonstrate the GIF gene is not the only gene involved in the physiopathology of inherited GIF deficiency. It is necessary to study the gastric causes of vitamin B12 malabsorption through a polygenic approach, in which the FUT2 gene is an important element

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 (&#8804;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 &#61549;g/day and 400 &#61549;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 &#61549;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 &#61603; 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.