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‣ Evaluation of plasma homocysteine level according to the C677T and A1298C polymorphism of the enzyme MTHRF in type 2 diabetic adults; Avaliação da homocisteína plasmática de acordo com o polimorfismo C677T e A1298C da enzima MTHRF em adultos diabéticos tipo 2

Mello, Adriana Lima; Carvalho da Cunha, Selma Freire de; Foss-Freitas, Maria Cristina; Vannucchi, Helio
Fonte: SBEM-SOC BRASIL ENDOCRINOLOGIA & METABOLOGIA; RIO DE JANEIRO, RJ Publicador: SBEM-SOC BRASIL ENDOCRINOLOGIA & METABOLOGIA; RIO DE JANEIRO, RJ
Tipo: Artigo de Revista Científica
Português
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Objective: To determine plasma homocysteine levels during fasting and after methionine overload, and to correlate homocysteinemia according to methylenetetrahydrofolate reductase (MTHFR) polymorphism in type 2 diabetic adults. Subjects and methods: The study included 50 type 2 diabetic adults (DM group) and 52 healthy subjects (Control group). Anthropometric data, and information on food intake, serum levels of vitamin B 12, folic acid and plasma homocysteine were obtained. The identification of C677T and A1298C polymorphisms was carried out in the MTHFR gene. Results: There was no significant difference in homocysteinemia between the two groups, and hyperhomocysteinemia during fasting occurred in 40% of the diabetic patients and in 23% of the controls. For the same polymorphism, there was not any significant difference in homocysteine between the groups. In the Control group, homocysteinemia was greater in those subjects with C677T and A1298C polymorphisms. Among diabetic subjects, those with the A1298C polymorphism had lower levels of homocysteine compared with individuals with C677T polymorphism. Conclusion: The MTHFR polymorphism (C677T and A1298C) resulted in different outcomes regarding homocysteinemia among individuals of each group (diabetic and control). These data suggest that metabolic factors inherent to diabetes influence homocysteine metabolism. Arq Bras Endocrinol Metab. 2012;56(7):429-34; OBJETIVO: Determinar os níveis plasmáticos de homocisteína de jejum e após sobrecarga de metionina e correlacionar a homocisteinemia com o polimorfismo C677T e A1298C da metilenotetra-hidrofolato redutase (MTHFR) em diabéticos tipo 2. SUJEITOS E MÉTODOS: O estudo incluiu 50 adultos diabéticos tipo 2 (Grupo DM) e 52 indivíduos saudáveis (Grupo controle). Obtiveram-se os dados antropométricos...

‣ Folato, vitamina B6 e B12: Ingestão dietética, níveis sanguíneos e relação com a concentração sérica de homocisteína em adolescentes de Indaiatuba, SP; Folate, vitamin B6 and B12: the relationship between serum homocysteine concentration and dietary intake and status of vitamins among adolescents of Indaiatuba, São Paulo.

Steluti, Josiane
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 24/08/2010 Português
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Introdução: O folato e outras vitaminas do complexo B estão metabolicamente relacionadas à elevação sanguínea do aminoácido homocisteína (hcy). Este, por sua vez, se mostrou associada ao aumento de risco de eventos adversos, sobretudo as doenças cardiovasculares. Objetivo: Investigar a ingestão dietética e níveis sanguíneos das vitaminas folato, B6, e B12, e sua relação com a concentração sérica de hcy, entre adolescentes Métodos: Estudo observacional, transversal, em adolescentes de ambos os sexos, faixa etária de 16 a 19 anos, foi conduzido na escola de ensino técnico da cidade de Indaiatuba-SP-Brasil. Coletou-se registro alimentar de três dias não consecutivos. Os valores dos nutrientes referentes aos registros foram obtidos no software NDSR. Para a estimativa da dieta habitual pela remoção da variabilidade intrapessoal e a prevalência de inadequação da ingestão pelo método da EAR como ponto de corte, utilizou-se o PC-Side, versão 1.0. As análises bioquímicas de folato, B6, B12 e hcy foram conduzidas de acordo com os métodos aceitos na literatura científica. Todas as análises estatísticas foram realizadas no STATA® versão 10.0 considerando o nível de significância 5%. Resultados: O estudo foi conduzido com 99 adolescentes...

‣ Homocisteína e cisteína séricas como marcadores epigenéticos de prognóstico e preditivos de resposta em tumores de mama; Serum homocysteine and cysteine as epigenetic markers of prognosis and prediction of response in breast tumors

Raimundo, Luis Gustavo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/02/2014 Português
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O câncer de mama é a principal causa de mortalidade por câncer entre as mulheres. Alguns biomarcadores e características clínicas são utilizados para avaliar o prognóstico e prever a resposta a uma série de abordagens terapêuticas. A Homocisteína é conhecida como um fator de risco para doença vascular aterosclerótica, mas sua participação na biologia do câncer ainda é incerta. Cisteína é o aminoácido sulfurado derivado da Homocisteína no ciclo da Metionina. Este ciclo metabólico origina as bases nitrogenadas e também determina o nível de metilação da molécula de DNA. É atualmente reconhecido que a hipometilação global do genoma é um evento chave na transformação maligna das células. O objetivo deste estudo foi avaliar os níveis séricos de homocisteína e cisteína como biomarcadores de sobrevida e de progressão da doença em câncer de mama. Também foi avaliado o efeito de um curso de curta duração (um mês) de tratamento hormonal sobre os níveis de Homocisteína, Cisteína e metilação do DNA. Amostras de sangue foram obtidos por ocasião da biópsia inicial (pré-tratamento) em todas as pacientes e, de tumor e de tecido normal adjacente, ao diagnóstico eem um mês após, para as pacientes que receberam o regime hormonal neo-adjuvante (pré-operatório). Todas as pacientes eram mulheres na pós-menopausa...

‣ Efeito da suplementação de ácido fólico e do exercício físico sobre as concentrações plasmáticas de indivíduos portadores de hipertensão arterial essencial ou Efeito da suplementação de ácido fólico e do exercício físico sobre as concentrações de homocisteína plasmática em indivíduos portadores de hipertensão arterial essencial; Effect of folic acid supplementation and physical exercises on plasma concentrations of homocysteine in essencial hypertensive subjects

Pereira, Avany Fernandes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/10/2004 Português
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A homocisteína plasmática é considerada marcador de risco para doenças cardiovasculares e sua associação com a hipertensão arterial essencial parece ser importante no agravamento desta doença. O exercício físico tem mostrado eficácia na redução da pressão arterial e o ácido fólico suplementar a dieta como a melhor conduta para a redução da homocisteinemia. O objetivo deste trabalho foi verificar o efeito da suplementação de ácido fólico e/ou do exercício físico sobre as concentrações plasmáticas de homocisteína em hipertensos essenciais medicados. Para tanto foram estudados 69 hipertensos (57±10 anos), sendo 22 do sexo masculino e 47 do sexo feminino, divididos em dois grupos: grupo 1 medicado com diurético e grupo 2 medicado sem diurético, sendo o tiazídico o diurético mais utilizado (80%). Foram realizadas avaliações médica, antropométrica, dietética, pressórica, bioquímica e o teste de aptidão cardiorrespiratória. Os indivíduos receberam suplementação com 500 µg/dia de ácido fólico, em estudo do tipo cruzado, e foram submetidos a treinamento com exercícios físicos supervisionados, sendo reavaliados a cada dois meses até o final do estudo. Os grupos foram homogêneos em relação a todas as variáveis estudadas exceto a homocisteína plasmática que foi maior significativamente no grupo 1. Não houve diferença significativa entre os sexos para todas as variáveis estudadas. Os hipertensos eram em sua maioria (62%) não controlados e portadores de síndrome metabólica (77%). O exercício físico apresentou efeito benéfico na reclassificação dos hipertensos leves e moderados para a classe de limítrofes sem normalizar a pressão arterial. Não houve efeito do exercício na composição corporal e na homocisteinemia. A suplementação de ácido fólico reduziu a hiperhomocisteinemia em 11% no grupo 1 e 19% no grupo 2 frente a aumentos similares na folacemia. Em relação à pressão arterial houve normalização da homocisteinemia apenas nos hipertensos com pressão arterial normalizada. Os hipertensos limítrofes e leves apresentaram reclassificação da hiperhomocisteinemia limítrofe para moderada. A presença de diurético potencializou a normalização da pressão pelo exercício físico e indiretamente influenciou...

‣ Evaluation of plasma homocysteine level according to the C677T and A1298C polymorphism of the enzyme MTHRF in type 2 diabetic adults

Mello,Adriana Lima; Cunha,Selma Freire de Carvalho da; Foss-Freitas,Maria Cristina; Vannucchi,Helio
Fonte: Sociedade Brasileira de Endocrinologia e Metabologia Publicador: Sociedade Brasileira de Endocrinologia e Metabologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 Português
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OBJECTIVE: To determine plasma homocysteine levels during fasting and after methionine overload, and to correlate homocysteinemia according to methylenetetrahydrofolate reductase (MTHFR) polymorphism in type 2 diabetic adults. SUBJECTS AND METHODS: The study included 50 type 2 diabetic adults (DM group) and 52 healthy subjects (Control group). Anthropometric data, and information on food intake, serum levels of vitamin B12, folic acid and plasma homocysteine were obtained. The identification of C677T and A1298C polymorphisms was carried out in the MTHFR gene. RESULTS: There was no significant difference in homocysteinemia between the two groups, and hyperhomocysteinemia during fasting occurred in 40% of the diabetic patients and in 23% of the controls. For the same polymorphism, there was not any significant difference in homocysteine between the groups. In the Control group, homocysteinemia was greater in those subjects with C677T and A1298C polymorphisms. Among diabetic subjects, those with the A1298C polymorphism had lower levels of homocysteine compared with individuals with C677T polymorphism. CONCLUSION:The MTHFR polymorphism (C677T and A1298C) resulted in different outcomes regarding homocysteinemia among individuals of each group (diabetic and control). These data suggest that metabolic factors inherent to diabetes influence homocysteine metabolism.

‣ Association of homocysteine and methylene tetrahydrofolate reductase (MTHFR C677T) gene polymorphism with coronary artery disease (CAD) in the population of North India

Tripathi,Rajneesh; Tewari,Satyendra; Singh,Prabhat Kumar; Agarwal,Sarita
Fonte: Sociedade Brasileira de Genética Publicador: Sociedade Brasileira de Genética
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 Português
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The implications of the methylene tetrahydrofolate reductase (MTHFR) gene and the level of homocysteine in the pathogenesis of coronary artery disease (CAD) have been extensively studied in various ethnic groups. Our aim was to discover the association of MTHFR (C677T) polymorphism and homocysteine level with CAD in north Indian subjects. The study group consisted of 329 angiographically proven CAD patients, and 331 age and sex matched healthy individuals as controls. MTHFR (C677T) gene polymorphism was detected based on the polymerase chain reaction and restriction digestion with HinfI. Total homocysteine plasma concentration was measured using immunoassay. T allele frequency was found to be significantly higher in patients than in the control group. We found significantly elevated levels of mean homocysteine in the patient group when compared to the control group (p = 0.00). Traditional risk factors such as diabetes, hypertension, smoking habits, a positive family history and lipid profiles (triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol), were found significantly associated through univariate analysis. Furthermore, multivariable logistics regression analysis revealed that CAD is significantly and variably associated with diabetes...

‣ Homocysteine: validation and comparison of two methods using samples from patients with pulmonary hypertension

Barbosa,Tatiana Maria Costa de Campos; Carvalho,Maria das Graças; Silveira,Josianne Nicácio; Rios,Júnia Garib; Komatsuzaki,Flávia; Godói,Lara Carvalho; Costa,Guilherme Hideki Yoshizane
Fonte: Sociedade Brasileira de Patologia Clínica; Sociedade Brasileira de Patologia; Sociedade Brasileira de Citopatologia Publicador: Sociedade Brasileira de Patologia Clínica; Sociedade Brasileira de Patologia; Sociedade Brasileira de Citopatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 Português
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Introduction and objective: The determination of homocysteine plasma levels has been reported as a risk marker of interest in severe diseases involving endothelial injury and associated with the development or progression of atherosclerotic lesions and thrombus formation. The aims of this study were to validate method for quantification of plasma homocysteine by high performance liquid chromatography (HPLC) with fluorimetric detection, and to compare the results obtained from patients with pulmonary hypertension by HPLC with those obtained by spectrophotometric enzymatic cycling (S-Ec) method. Materials and methods: The validation parameters, such as linearity, matrix effect, precision, accuracy, detection and quantitation limits, and robustness of the method were evaluated aiming to demonstrate that it is suitable for the intended use. The data obtained in the quantification of homocysteine using the validated method (HPLC) and the spectrophotometric enzymatic cycling (S-Ec) method, were compared. Results: The method was precise, accurate, and robust; it also had good recovery and showed no matrix effect. The linearity covered a range of 5.0-85.0 µmol/l and the limits of detection and quantification were 1.0 µmol/l and 3.4 µmol/l...

‣ What is the influence of hormone therapy on homocysteine and crp levels in postmenopausal women?

Lakryc,Eli Marcelo; Machado,Rogério Bonassi; Soares Jr,José Maria; Baracat,Edmund Chada
Fonte: Faculdade de Medicina / USP Publicador: Faculdade de Medicina / USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 Português
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OBJECTIVE: To evaluate the influence of estrogen therapy and estrogen-progestin therapy on homocysteine and C-reactive protein levels in postmenopausal women. METHODS: In total, 99 postmenopausal women were included in this double-blind, randomized clinical trial and divided into three groups: Group A used estrogen therapy alone (2.0 mg of 17β-estradiol), Group B received estrogen-progestin therapy (2.0 mg of 17 β-estradiol +1.0 mg of norethisterone acetate) and Group C received a placebo (control). The length of treatment was six months. Serum measurements of homocysteine and C-reactive protein were carried out prior to the onset of treatment and following six months of therapy. RESULTS: After six months of treatment, there was a 20.7% reduction in homocysteine levels and a 100.5% increase in C-reactive protein levels in the group of women who used estrogen therapy. With respect to the estrogen-progestin group, there was a 12.2% decrease in homocysteine levels and a 93.5% increase in C-reactive protein levels. CONCLUSION: Our data suggested that hormone therapy (unopposed estrogen or estrogen associated with progestin) may have a positive influence on decreasing cardiovascular risk due to a significant reduction in homocysteine levels.

‣ The homocysteine controversy

Smulders, Yvo M.; Blom, Henk J.
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
Português
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Mild to moderate hyperhomocysteinemia has been identified as a strong predictor of cardiovascular disease, independent from classical atherothrombotic risk factors. In the last decade, a number of large intervention trials using B vitamins have been performed and have shown no benefit of homocysteine-lowering therapy in high-risk patients. In addition, Mendelian randomization studies failed to convincingly demonstrate that a genetic polymorphism commonly associated with higher homocysteine levels (methylenetetrahydrofolate reductase 677 C>T) is a risk factor for cardiovascular disease. Together, these findings have cast doubt on the role of homocysteine in cardiovascular disease pathogenesis, and the homocysteine hypothesis has turned into a homocysteine controversy. In this review, we attempt to find solutions to this controversy. First, we explain that the Mendelian randomization analyses have limitations that preclude final conclusions. Second, several characteristics of intervention trials limit interpretation and generalizability of their results. Finally, the possibility that homocysteine lowering is in itself beneficial but is offset by adverse side effects of B vitamins on atherosclerosis deserves serious attention. As we explain...

‣ Overview of homocysteine and folate metabolism. With special references to cardiovascular disease and neural tube defects

Blom, Henk J.; Smulders, Yvo
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
Português
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This overview addresses homocysteine and folate metabolism. Its functions and complexity are described, leading to explanations why disturbed homocysteine and folate metabolism is implicated in many different diseases, including congenital birth defects like congenital heart disease, cleft lip and palate, late pregnancy complications, different kinds of neurodegenerative and psychiatric diseases, osteoporosis and cancer. In addition, the inborn errors leading to hyperhomocysteinemia and homocystinuria are described. These extreme human hyperhomocysteinemia models provide knowledge about which part of the homocysteine and folate pathways are linked to which disease. For example, the very high risk for arterial and venous occlusive disease in patients with severe hyperhomocysteinemia irrespective of the location of the defect in remethylation or transsulphuration indicates that homocysteine itself or one of its “direct” derivatives is considered toxic for the cardiovascular system. Finally, common diseases associated with elevated homocysteine are discussed with the focus on cardiovascular disease and neural tube defects.

‣ Homocysteine and pregnancy

Hague, W.
Fonte: Bailliere Tindall Publicador: Bailliere Tindall
Tipo: Artigo de Revista Científica
Publicado em //2003 Português
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Homocysteine is an amino acid that is involved in several key metabolic processes, including the methylation and sulphuration pathways. Blood concentrations of homocysteine are determined by various dietary factors, including folic acid and vitamin B(12), by alteration in physiology, such as renal impairment, and by variation in the activity of enzymes in the various pathways as a result of genetic polymorphisms, some of which are commonly found in the population. Hyperhomocysteinaemia has been associated with vascular disease, although whether it is cause or effect is still a matter of debate. In normal pregnancy, homocysteine concentrations fall. Disturbance of maternal and fetal homocysteine metabolism has been associated with fetal neural tube defects, with various conditions characterized by placental vasculopathy, such as pre-eclampsia and abruption, and with recurrent pregnancy loss. Apart from folate supplementation, which has been clearly shown to halve the risk of fetal neural tube defects, no other strategies have been identified in relation to homocysteine metabolism that will reliably reduce the frequency of these other common obstetric pathologies.

‣ Homocysteine and C-reactive protein are not markers of cognitive impairment in patients with major cardiovascular disease

Silbert, B.; Evered, L.; Scott, D.; McCutcheon, C.; Jamrozik, K.
Fonte: Karger Publicador: Karger
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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BACKGROUND: Raised concentrations of plasma homocysteine and C-reactive protein (CRP) are associated with vascular disease and have also been implicated as independent risk factors for cognitive impairment in population studies. OBJECTIVES: To investigate the association of plasma homocysteine and CRP with cognition in patients scheduled for coronary artery bypass graft (CABG) surgery. Cognition was assessed in 264 patients using a standard battery of neuropsychological tests. Patients were classified as having preexisting cognitive impairment (PreCI) by reference to a healthy control group or postoperative cognitive dysfunction (POCD) by reference to baseline test scores. RESULTS: PreCI was present in 37.3% of patients, and POCD was present in 18.3, 12.1 and 13.6% of patients at 1 week, 3 months and 12 months postoperatively. On multivariate analysis neither homocysteine nor CRP were independently associated with cognition at any testing time but were strongly associated with age and left ventricular function. CONCLUSION: PreCI and POCD are present in a substantial proportion of patients undergoing CABG surgery but there is no independent association with either baseline homocysteine or CRP levels. It is possible that cognitive impairment may result from the vascular disease rather than a direct association with either homocysteine or CRP.; Brendan Silbert...

‣ Folate, Vitamin B12, Vitamin B6 and homocysteine: impact on pregnancy outcome

Furness, D.; Fenech, M.; Dekker, G.; Khong, T.; Roberts, C.; Hague, W.
Fonte: Wiley-Blackwell Publishing Ltd Publicador: Wiley-Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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Good clinical practice recommends folic acid supplementation 1 month prior to pregnancy and during the first trimester to prevent congenital malformations. However, high rates of fetal growth and development in later pregnancy may increase the demand for folate. Folate and vitamins B12 and B6 are required for DNA synthesis and cell growth, and are involved in homocysteine metabolism. The primary aim of this study was to determine if maternal folate, vitamin B12, vitamin B6 and homocysteine concentrations at 18–20 weeks gestation are associated with subsequent adverse pregnancy outcomes, including pre-eclampsia and intrauterine growth restriction (IUGR). The secondary aim was to investigate maternal B vitamin concentrations with DNA damage markers in maternal lymphocytes. A prospective observational study was conducted at the Women's and Children's Hospital, Adelaide, South Australia. One hundred and thirty-seven subjects were identified prior to 20 weeks gestation as at high or low risk for subsequent adverse pregnancy outcome by senior obstetricians. Clinical status, dietary information, circulating micronutrients and genome damage biomarkers were assessed at 18–20 weeks gestation. Women who developed IUGR had reduced red blood cell (RBC) folate (P < 0.001) and increased plasma homocysteine concentrations (P < 0.001) compared with controls. Maternal DNA damage...

‣ Investigation into the relationship between Physical Activity and Homocysteine

Schneeberg, Amy
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 593332 bytes; application/pdf
Português
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Background: A beneficial effect of physical activity on the risk of cancer at several sites has been consistently observed. Biologic mechanisms that may underlie this relationship are not well understood. A potential mechanism explaining this relationship for some cancer sites is the influence of physical activity on methionine-homocysteine biosynthesis. High levels of total plasma homocysteine concentration (tHcy) indicate a breakdown in this biochemical process. This cycle’s influences on DNA methylation and endogeneous agents involved in oxidative stress are potential mechanisms linking methionine-homocysteine biosynthesis to cancer risk. This research is nested within a larger cross sectional study of healthy volunteers recruited from centers in Ontario and Nova Scotia aimed at understanding modifiable risk factors for cancer. Purpose: This research sought to elucidate the relationship between physical activity and tHcy level. Methods: The target population was healthy male and female subjects aged 20-50. Participants donate a 12ml blood sample after an overnight fast for analysis of tHcy and dietary factors and complete a questionnaire including a physical activity profile for the past month (adapted from the International Physical Activity Questionnaire [IPAQ]) and established predictors of tHcy level such as coffee and alcohol consumption. Multiple linear regression is used to model the relationship between tHcy and physical activity measures while controlling for potential confounders. Results: Analysis on 171 participants has been carried out. Mean tHcy for five quintiles of physical activity (from lowest physical activity score to highest) were found to be 8.40μmol/L (7.76-9.05)...

‣ Preditores sócio-demográficos, de estilo de vida e gineco-obstétricos das concentrações séricas ou plasmáticas de homocisteína, ácido fólico e vitaminas B12 e B6 em mulheres de baixa renda de São Paulo, Brasil; Socio-demographic, lifestyle, gynecological, and obstetric predictors of serum or plasma concentrations of homocysteine, folic acid, and vitamins B12 and B6 among low-income women in São Paulo, Brazil

ALMEIDA, Lana Carneiro; TOMITA, Luciana Yuki; D'ALMEIDA, Vânia; CARDOSO, Marly Augusto
Fonte: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz Publicador: Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz
Tipo: Artigo de Revista Científica
Português
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O presente estudo investigou fatores sócio-demográficos, de estilo de vida e gineco-obstétricos associados às concentrações séricas ou plasmáticas de homocisteína, ácido fólico, vitaminas B12 e B6 em mulheres de baixa renda de São Paulo, Brasil. Concentrações séricas de ácido fólico e vitamina B12 foram analisadas por fluoroimunoensaio; concentrações plasmáticas de homocisteína e vitamina B6, por cromatografia líquida de alta performance em fase reversa. Variáveis independentes foram inicialmente selecionadas segundo pressupostos teóricos, correlação de Pearson ou teste Kruskal-Wallis (p < 0,20). Concentrações alteradas segundo pontos de corte para homocisteína, ácido fólico, vitaminas B12 e B6 foram observadas em 20%, 6%, 11% e 67% das participantes, respectivamente. Idade foi positivamente correlacionada à vitamina B6 e homocisteína plasmáticas (p < 0,001). Índice de massa corporal foi positivamente correlacionado à vitamina B6 plasmática (p < 0,001). Modelos de regressão linear múltiplos explicaram 10,2%, 5,8%, 14,4% e 9,4% das concentrações de ácido fólico, vitamina B12, vitamina B6 e homocisteína, respectivamente. No presente estudo, variáveis sócio-demográficas, de estilo de vida e gineco-obstétricas apresentaram contribuição importante na variação das concentrações dos indicadores bioquímicos avaliados.; This study examined the socio-demographic...

‣ Betaine homocysteine S-methyltransferase: just a regulator of homocysteine metabolism?

Pajares, María A.; Pérez-Sala, Dolores
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Artículo Formato: 1013853 bytes; application/pdf
Português
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El pdf del artículo es la versión de autor.; Betaine homocysteine methyltransferase (BHMT), a Zn2+-dependent thiolmethyltransferase, contributes to the regulation of homocysteine levels, whose increases are considered a risk factor for cardiovascular diseases. Most plasma homocysteine is generated through the liver methionine cycle, in which BHMT metabolizes approximately 25% of this non-protein amino acid. This process allows recovery of one of the three methylation equivalents used in phosphatidylcholine synthesis through transmethylation, a major homocysteine producing pathway. Although BHMT has been known for over 40 years the difficulties encountered in its isolation precluded detailed studies until very recently. Thus, the last 10 years, since the sequence became available, have yielded extensive structural and functional data. Moreover, recent findings offer clues for potential new functions for BHMT. The purpose of this review is to provide an integrated view of the knowledge available on BHMT, and to analyze its putative roles in other processes through interactions undercover to date.; Ministerio de Educación y Ciencia (PM 97/0064, BMC 2002-0243 and BFU 2005-00050 to M.A.P. and SAF 2003-03713 to D.P-S.) and Fondo de Investigación Sanitaria (FIS 01/1077 and RCMN C03/08 to M.A.P.; Peer reviewed

‣ Geriatric psychiatry: is the jury still out on the cognitive effects of homocysteine and one-carbon metabolism?

Looi, Jeffrey; Sachdev, Perminder Singh
Fonte: Lippincott Williams & Wilkins Publicador: Lippincott Williams & Wilkins
Tipo: Artigo de Revista Científica
Português
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Purpose of review: This review considers the evidence for the contribution of hyperhomocysteinemia to cognitive impairment, the dementias and Parkinson's disease, focusing on published literature from April 2002 to April 2003. Recent findings: Homocysteine is a sulphur-containing amino acid that is involved in cycles related to one-carbon metabolism within the body, and elevations in its level can result from multiple aspects of these cycles. Elevated homocysteine impairs methylation, crucial to DNA synthesis and repair, is toxic to the vascular system, is cytotoxic and is directly neurotoxic. These effects interact with ageing-related pathology and toxins to augment neurodegenerative processes. Controversies remain in the ascertainment of homocysteine levels and in the salience of its contribution to cognitive impairment, the dementias and Parkinson's disease. However, cross-sectional studies generally agree homocysteine levels greater than 14 μmol/l are associated with increased risk of cognitive impairment. Hyperhomocysteinemia is associated with an increased risk of cognitive impairment after stroke, and is a contributory factor to the cognitive deficits of vascular dementia and AD. Elevated homocysteine levels have been demonstrated in L-dopa treated Parkinson's disease patients in associated with vascular risk. Hyperhomocysteinemia is also associated with increased brain atrophy in healthy elderly. Summary: There is an increasingly solid case for the association between hyperhomocysteinemia...

‣ Relationship of homocysteine, folic acid and vitamin B12 with depression in middleaged community sample

Sachdev, Perminder Singh; Parslow, Ruth; Lux, Ora; Salonikas, Chris; Wen, Wei; Naidoo, Daya; Christensen, Helen; Jorm, Anthony F
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
Português
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37.257083%
Background. Case control studies have supported a relationship between low folic acid and vitamin B12 and high homocysteine levels as possible predictors of depression. The results from epidemiological studies are mixed and largely from elderly populations. Method. A random subsample of 412 persons aged 60-64 years from a larger community sample underwent psychiatric and physical assessments, and brain MRI scans. Subjects were assessed using the PRIME-MD Patient Health Questionnaire for syndromal depression and severity of depressive symptoms. Blood measures included serum folic acid, vitamin B12, homocysteine and creatinine levels, and total antioxidant capacity. MRI scans were quantified for brain atrophy, subcortical atrophy, and periventricular and deep white-matter hyperintensity on T2-weighted imaging. Results. Being in the lowest quartile of homocysteine was associated with fewer depressive symptoms, after adjusting for sex, physical health, smoking, creatinine, folic acid and B12 levels. Being in the lowest quartile of folic acid was associated with increased depressive symptoms, after adjusting for confounding factors, but adjustment for homocysteine reduced the incidence rate ratio for folic acid to a marginal level. Vitamin B12 levels did not have a significant association with depressive symptoms. While white-matter hyperintensities had significant correlations with both homocysteine and depressive symptoms...

‣ The effect of increased concentrations of homocysteine on the concentration of (E)-4-hydroxy-2-nonenal in the plasma and cerebrospinal fluid of patients with alzheimers disease

Selley, M; Close, D R; Stern, Steven
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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37.356077%
There is evidence that increased blood concentrations of homocysteine may be a risk factor for Alzheimer's disease. (E)-4-hydroxy-2-nonenal (HNE) is a neurotoxic product of lipid peroxidation that is increased in the ventricular fluid and brains of patients with Alzheimer's disease. We measured the concentrations of homocysteine, HNE, vitamin B12 and folate in the plasma of 27 patients with Alzheimer's disease and 25 control subjects. There was a statistically significant increase in the plasma concentration of homocysteine (P < 0.001) and HNE (P < 0.001) in the Alzheimer's disease patients compared to the control group. There was a significant decrease in the plasma concentration of vitamin B12 (P < 0.001) and folate (P = 0.002) in the Alzheimer's group compared to the controls. There was a significant positive correlation between the plasma concentrations of homocysteine and HNE in the patients with Alzheimer's disease (r = 0.661, P < 0.001). A significant negative correlation was found between the plasma concentration of homocysteine and the plasma concentrations of vitamin B12 (r = -0.605, P = 0.0006) and folate (r = 0.586, P = 0.001). We also measured the concentrations of homocysteine, HNE, vitamin B12 and folate in the cerebrospinal fluid (CSF) of 8 patients with Alzhiemer's disease compared to 6 control subjects. The concentrations of homocysteine (P = 0.032) and HNE (P = 0.001) were significantly higher in the CSF of Alzheimer's patients than in the control subjects. There were significant positive correlations between the CSF concentrations of homocysteine and HNE (r = 0.924...

‣ Homocysteine, type 2 diabetes mellitus, and cognitive performance: The Main-Syracuse Study

Robbe, J-M; Elias, Merrill F; Budge, Marc; Brennan, Suzanne L; Elias, Penelope K
Fonte: Walter de Gruyter Publicador: Walter de Gruyter
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.306418%
Type 2 diabetes mellitus and higher total plasma homocysteine concentrations are each associated with an increased incidence of cardiovascular disease and with diminished cognitive performance. Relations between homocysteine concentrations and cardiovascular disease incidence are stronger in the presence of type 2 diabetes mellitus. Therefore, we hypothesized that relations between homocysteine concentrations and cognitive performance would be stronger in the presence of type 2 diabetes. We related homocysteine concentrations and cognitive performance on the Mini-Mental State Examination in 817 dementia and stroke-free participants of the Maine-Syracuse Study, 90 of whom were classified with type 2 diabetes mellitus. Regardless of statistical adjustment for age, sex, gender, vitamin co-factors (folate, vitamin B6, vitamin B12), cardiovascular disease risk factors, and duration and type of treatment for type 2 diabetes mellitus, statistically significant inverse associations between homocysteine concentrations and cognitive performance were observed for diabetic individuals. The weaker inverse associations between homocysteine concentrations and cognitive performance obtained for non-diabetic individuals were not robust to statistical adjustment for some covariates. Interactions between homocysteine concentrations and type 2 diabetes mellitus are observed such that associations between homocysteine and cognitive performance are stronger in the presence of diabetes.