• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 100
  • 73
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 3
  • 2
  • Tagged with
  • 246
  • 62
  • 55
  • 47
  • 32
  • 32
  • 28
  • 28
  • 27
  • 24
  • 22
  • 19
  • 19
  • 17
  • 17
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Ingestão alimentar, homocisteína e proteoma plasmático no lúpus eritematoso sistêmico juvenil / Food intake, homocysteine and plasma proteomic in childhood-onset systemic lupus erythematosus

Salomão, Roberta Garcia 05 August 2016 (has links)
Lúpus eritematoso sistêmico (LES) é uma doença multisistêmica crônica e autoimune de etiologia desconhecida. O LES é considerado um fator de risco independente para eventos cardiovasculares em qualquer faixa etária. A coexistência de fatores de risco tradicionais e não tradicionais (alto nível plasmático de homocisteína) são as causas para o risco do desenvolvimento de doenças cardiovasculares (DCV) em portadores de LES. A hiperhomocisteinemia é considerada um fator de risco independente para DCV e cerebrovasculares e tem como causas fatores nutricionais, genéticos e fisiológicos. Proteína C reativa de alta sensibilidade (hs-PCR), fator de necrose tumoral-? (TNF- ?), interferon ?, MCP-1 (Monocyte Chemoattractant Protein- 1) e leptina tem sido descritos como importantes biomarcadores para DCV. Por outro lado, adiponectina e grelina tem sido retratadas como potentes protetores contra o desenvolvimento da aterosclerose. Parâmetros antropométricos aumentados também podem estar associados ao risco de DCV como aumento da espessura da camada íntima da carótida. O processo de inflamação crônica existente no LES está diretamente associado a alterações no perfil lipídico e no metabolismo de lipoproteínas. Análises em larga escala dos perfis de expressão de proteínas estão se tornando uma importante ferramenta na investigação de várias patologias associadas a resposta autoimune. Objetivos: Descrever e comparar medidas antropométricas, ingestão alimentar e proteoma plasmático em pacientes com lúpus eritematoso sistêmico juvenil (LESJ) e controles saudáveis. Comparar metabólitos e antropometria entre dois clusters metabólicos de pacientes com LESJ (Lúpus Melhor Perfil Metabólico - LMPM e Lúpus Pior Perfil Metabólico - LPPM) e um cluster com controles saudáveis (Controle Melhor Perfil Metabólico) e, também, em dois clusters de pacientes com LESJ definidos pela dose diária de corticoide administrada. Métodos: Foram recrutadas 19 adolescentes portadoras de LESJ e 39 controles saudáveis. Foram mensurados índice de massa corporal (IMC), peso, estatura, circunferência da cintura (CC), ingestão alimentar (Recordatório de 24 horas), SLEDAI (Systemic Lupus Erythematosus Disease Activity Index), SLICC (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), níveis plasmáticos de homocisteína, vitamina B12, 6 folato, TNF-?, hs-PCR, MCP-1, adiponectina, leptina, grelina, perfil lipídico e proteoma plasmático pela técnica Shotgun proteomics com Isobaric Tag for Relative and Absolute Quantitation. Os grupos foram comparados por ANCOVA. k-cluster foi usado para separar LESJ e controles em dois clusters extremos de melhor e pior perfil metabólico de acordo com os níveis plasmáticos de homocisteína, TNF-?, hsPCR e folato para a análise da proteômica. Resultados: Pacientes com LESJ apresentaram maior IMC, CC, homocisteína, triglicérides, TNF-?, hsPCR e menor folato plasmático quando comparados ao grupo controle. Foram encontradas 10 proteínas com expressão significativamente diferente entre os clusters: Cluster Lúpus Melhor Perfil Metabólico (LMPM), Cluster Lúpus Pior Perfil Metabólico (LPPM) e Cluster Controle Melhor Perfil Metabólico (CMPM) (? -2-macroglobulina, ? -1-antitripsina, apoliproteína AI, apoliproteína E, ceruloplasmina, complemento C3, fibrinogênio de cadeia ?, haptoglobina, hemopexina e sorotransferrina). Oito proteínas foram mais expressas no LMPM e menos expressas no LPPM comparados com CMPM. As proteínas menos expressas no LPPM foram negativamente correlacionadas com maior risco para DCV. Conclusão: O presente estudo mostrou que as adolescentes com LESJ apresentaram maior IMC, circunferência da cintura, concentrações séricas de homocisteína, triglicérides, TNF-?, hs-PCR e, menor estatura e concentração de folato sérico quando comparadas com adolescentes saudáveis. Além disso, o cluster LPPM apresentou uma expressão diminuída das proteínas apolipoproteína AI, apolipoproteína E, alfa-2- macroglobulina, alfa-1-antitripsina, ceruloplasmina, complemento C3, hemopexina e sorotransferrina quando comparado aos clusters CMPM e LMPM. Sendo assim, é possível concluir que o presente estudo sinaliza possíveis complicações cardiovasculares futuras em pacientes com LESJ e, sugerem a necessidade de novos estudos, a fim de elucidar a interação do estado nutricional e das proteínas encontradas pela proteômica no contexto de sistemas biológicos em pacientes com LESJ. / Systemic lupus erythematosus (SLE) is a, autoimmune, chronic and inflammatory disease of unknown etiology. SLE is considered an independent risk factor for cardiovascular diseases at any age. Reasons for the increased risk of CVD in SLE include the co-existence of traditional cardiac risk factors and nontraditional risk factors such as high concentrations of homocysteine. Elevated homocysteine (Hcy) levels is considered an independent risk factor for CVD. Hiperhomocysteine can indicate undernourishment due to a lack of vitamins or genetic alterations. Inflammatory biomarkers have been consistently associated with the presence of CVD in multiple studies from different populations, including SLE, such as high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor - ? (TNF - ?), type I interferon (IFN), monocyte chemoattractant protein-1 (MCP-1) and leptin. On the other hand, some cytokines and hormones are related to atherosclerosis prevention, such as adiponectin and ghrelin. The existing chronic inflammation process in SLE is directly associated with changes in lipid and lipoprotein metabolism. Some comprehensive studies have been conducted at multiple biological levels including DNA (or genomics), mRNA (or transcriptomics), protein (or proteomics) and metabolites (or metabolomics). The \'omics\' platforms allow us to re-examine SLE at a greater degree of molecular resolution. Objectives: To describe and compare anthropometric measurements, food intake, metabolites and plasma proteomic analysis in child-hood onset systemic lupus erythematosus (c-SLE) and healthy controls. To compare metabolites and anthropometric parameters between two clusters with c-SLE (lupus cluster with the best - LCBMP and the worst metabolic profile - LCWMP) and one cluster with controls (healthy cluster with the best metabolic profile - HCBMP) and to compare metabolites and anthropometric parameters between two clusters of c-SLE patients defined by daily corticosteroid doses intake. Methods: 19 c-SLE and 39 healthy volunteers were recruited. We evaluated BMI, weight, height, waist circumference, food intake through a 24-hours recalls, SLEDAI (Systemic Lupus Erythematosus Disease Activity Index), SLICC (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index), SLICC, serum levels of homocysteine, vitamin B12, 8 folate, TNF-?, hs-C reactive protein, monocyte chemoattractant protein-1, adiponectin, leptin, ghrelin, lipid profile and plasma proteomic by Shotgun proteomics with Isobaric Tag for Relative and Absolute Quantitation. The groups were compared by ANCOVA. k-cluster were used to separate SLE and control groups into two different clusters with the best and the worst metabolic profile according to homocysteine, TNF-?, hsCRP and folate plasma levels for proteomic assessment. Results: SLE patients presented higher BMI, WC, homocysteine, triglycerides, TNF-?, hsCRP levels and lower plasma folate when compared to controls. We found 10 proteins with significantly different expression between healthy cluster with the best metabolic profile (HCBMP) and lupus cluster with the best (LCBMP) and the worst metabolic profile (LCWMP) (alpha-2- macroglobulin; alpha-1-antitripsin, apoliprotein AI, apoliprotein E, ceruloplasmin, complement C3, fibrinogen ? chain, haptoglobin, hemopexin and serum transferrin). Eight proteins were higher expressed in LCBMP and lower expressed in LCWMP compared with HCBMP. Proteins less expressed in LCWMP were negatively correlated with a higher risk for cardiovascular disease. Conclusion: Our results described some previously cardiovascular risk factors in c-SLE patients and possible associations between nutritional status and cardiovascular disease risk factors. Proteomic results showed acute phase proteins and pro-inflammatory proteins more expressed in c-SLE patients compared to controls. These results might allow us to treat c-SLE with personalized diets to avoid cardiovascular complications in future. The small sample size and the cross-sectional design were the limitations of the study, but it is a rare disease in the pediatric field and, despite this fact, the present study was able to characterize two distinct nutritional and metabolic groups with uncommon proteins expressed. These results deserve further investigations to better elucidate the whole of these proteins in the context of systems biology interactions in SLE pediatric patients.
172

Efeitos dos polimorfismos no gene TC2 nas concentrações dos metabólicos marcadores da deficiência de cobalamina em gestantes e seus recém nascidos / Effects of polymorphisms in TC2 gene on concentrations of metabolites cobalamin deficient markers of metabolism in pregnant women and their neonates

Trentin, Renata 28 June 2006 (has links)
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.
173

Aspectos da morfofuncionalidade cardiovascular, variabilidade cardíaca e do estresse oxidativo em diferentes modelos experimentais de hiper-homocisteinemia

Mendes, Roberta Hack January 2009 (has links)
Com base na relevância das doenças cardiovasculares para a saúde pública mundial, buscamos entender as associações entre o metabolismo da homocisteína (Hcy) e este sistema, o estresse oxidativo (EO) e a possível influência da modulação do sistema nervoso simpático (SNS) sobre esta associação. Além disso, testamos o efeito da vitamina B6 sobre a função cardíaca e o EO. Para isso foram realizados dois experimentos: no primeiro testamos dois modelos de hiper-homocisteinemia (Hhe): o tratamento com metionina e homocisteína tiolactona em dois diferentes protocolos experimentais. No primeiro protocolo foram avaliados parâmetros morfofuncionais cardíacos e associações com o balanço redox no miocárdio. Já no segundo protocolo foi avaliada a variabilidade da freqüência cardíaca (VFC) e da pressão arterial sistólica (VPAS) e suas associações com o estresse oxidativo (EO) nos eritrócitos. Como resultados, observamos que os dois tratamentos resultam em igual aumento na concentração plasmática de Hcy, piora na função cardíaca e aumento no EO cardíaco. Além disso, foram encontradas fortes correlações entre as variáveis que sugerem piora da função cardíaca e desbalanço redox. O segundo protocolo demonstrou redução da VFC, com aumento do componente de baixa frequência (BF), associado ao SNS, e redução da modulação do sistema nervoso parasimpático ou de alta freqüência (AF), em valores normalizados. Quanto à VPAS foi demonstrado um aumento somente no componente de AF em ambos os tratamentos. Comparados ao grupo controle, a sensibilidade barorreflexa estava reduzida nos dois tratamentos (MET e HcyT), provavelmente devido ao aumento da modulação simpática vascular. Foi observado também um aumento da atividade das enzimas superóxido dismutase (SOD) e catalase (CAT) nos eritrócitos e redução na concentração das carbonilas. Esses resultados sugerem alteração no controle autonômico em favor da modulação simpática cardíaca e vascular, com piora na sensibilidade barorreflexa após o tratamento com HcyT. Além disso, estão associadas a uma maior mobilização das defesas enzimáticas resultando em redução do dano oxidativo. O segundo experimento consistiu do estabelecimento da Hhe após tratamento com HcyT, seguido por adição de vitamina B6 a água de beber como proposta terapêutica. Neste experimento avaliamos a concentração de Hcy e cisteína, parâmetros morfofuncionais cardíacos, atividade das enzimas antioxidantes sistêmicas, a concentração cardíaca de peróxido de hidrogênio (H2O2), imunoconteúdo da glutationa S-transferase (GST) e do fator de transcrição nuclear (Nrf2). O tratamento com vitamina B6 demonstrou redução na Hcy plasmática. Por outro lado, o tratamento com HcyT e vitamina B6 provocou aumento significativo da espessura da parede posterior cardíaca e da massa do ventrículo, todos corrigidos pelo peso corporal. Esses resultados sugerem uma hipertrofia ventricular compensatória. Além disso, o mesmo tratamento melhorou a função global miocárdica e a fração de ejeção. A atividade da SOD e CAT nos eritrócitos estava diminuída após o tratamento com vitamina B6, o que pode ocorrer devido às propriedades antioxidantes conhecidas da vitamina. Tanto a GST, quanto o Nrf2 apresentam aumento após o tratamento com HcyT, o que pode ser uma resposta adaptativa ao aumento de cisteína. O mesmo aumento foi observado no H2O2 após o tratamento com HcyT, sugerindo sinalização para o aumento do EO. A vitamina B6 possui propriedades que lhe conferem ação antioxidante, o que pode estar auxiliando no seu papel protetor no miocárdio e na condição de Hhe. Com esse trabalho, sugere-se que a Hhe seja vista de uma forma mais ampla que o simples aumento da Hcy no plasma, pois o seu metabolismo no organismo pode ter efeitos tóxicos, com repercussão na função cardíaca e modulação do SNS associados ao EO. Além disso, a vitamina B6 pode ser avaliada com proposta terapêutica isolada, pois atua reduzindo a concentração de Hcy e beneficiando o equilíbrio redox. / Based on the relevance of cardiovascular diseases to public health worldwide, we seek to understand its association to the homocysteine (Hcy) metabolism, the oxidative stress (OS) and the possible influence of the sympathetic nervous system (SNS) modulation. In addition, we tested the effect of vitamin B6 on cardiac function and OS. For this purpose two experiments were conducted: in the first experiment we tested two different hiperhomocysteinemia experimental models: methionine and homocysteine thiolactone, this experiment was divided into two protocols. At the first protocol to evaluate morpho-functional cardiac and associations to redox balance in the heart. Already at the other protocol was studied heart rate variability (HRV) and blood pressure (VPAS), and their associations with OS. The first experiment showed the effect of methionine (MET) and homocysteine thiolactone (HcyT) treatment on cardiac function and their associations with the OS. We found that both treatments result in equal increases in plasma Hcy, poor cardiac function and increase in cardiac OE. Furthermore, we found strong correlation between the variables that suggest worsening of cardiac function and increase in the OE. The toxicity of the thiolactone metabolite is known mainly in the nervous system, and the proposed mechanism for their deleterious effects on cardiac function is probably associated with a higher OE. The second protocol showed that HRV was reduced probably due to the increase in lowfrequency (LF), associated with the SNS, and a reduction in parasympathetic nervous system modulation or high-frequency (HF), in normalized values. The systolic blood pressure variability was demonstrated due to an increase in the HF component. Compared to the control group, baroreflex sensitivity was reduced in both treatments (MET and HcyT), probably due to the increase in sympathetic modulation. We also observed an increase in superoxide dismutase (SOD) and catalase (CAT) activity in erythrocytes, and also a reduced carbonyl concentration. These results suggest changes in cardiovascular autonomic control in favor to sympathetic modulation, with worsening in baroreflex sensitivity after HcyT treatment. They are also associated with greater enzymatic defenses mobilization resulting in reduced oxidative damage. The second experiment aim was study the effects of B6 treatment after Hhe, and we evaluated the Hcy and cysteine plasma concentration, the morphofunctional cardiac transcription factor of the antioxidant enzymes (Nrf2), glutathione S-transferase (GST), the hydrogen peroxide (H2O2) cardiac concentration and the enzymatic antioxidant activity. Vitamin B6 treatment reduced plasma homocysteine concentration. Furthermore, vitamin B6 and HcyT treatment caused a significant increase in posterior wall thickness and cardiac ventricular mass, all adjusted to body weight. These results suggest a compensatory ventricular hypertrophy. Moreover, the same treatment improved global myocardial function and ejection fraction. Both, Nrf2 and GST, have increased after HcyT treatment, which may be an adaptive response to increased cysteine. The same increase was observed in H2O2 after HcyT treatment, suggesting an increase in the OE. These results are confirmed by the increased SOD and CAT activity in erythrocytes. Vitamin B6 has antioxidant properties which may be aiding in its protective role in the myocardium and provided Hhe. Our results suggest that Hhe is seen in a broader than the simple increase of plasma Hcy, because their metabolism in the body can have toxic effects, with impact on cardiac function and SNS modulation associated with OE. In addition, vitamin B6 could be evaluated with therapeutic purposes by reducing the Hcy concentration and benefiting the redox balance.
174

Physical conditioning, total plasma homocysteine concentration and cardiovascular function in middle-aged men with coronary heart disease risk factors / Rumada Nel

Nel, Rumada January 2006 (has links)
Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007.
175

Alimentäres Methionin und Hyperhomocysteinämie / Alimentary Methionine and Hyperhomocysteinemia

Pexa, Annette 10 January 2007 (has links) (PDF)
Eine erhöhte Konzentration von Homocystein im Plasma (Hyperhomocysteinämie) gilt als unabhängiger Risikoindikator für neuronale und kardiovaskuläre Erkrankungen. Der Präcursor des Homocysteins, Methionin, ist eine essentielle Aminosäure, die bei Fehlernährung übermäßig verzehrt werden kann. Es wurde untersucht, ob tatsächlich durch langfristigen erhöhten Methioninverzehr via Erhöhung des Homocysteinspiegels im Plasma ein reales Gesundheitsrisiko besteht. Als Modell wurde eine Füttterungsstudie an Ratten gewählt, deren Bedingungen bezüglich Fütterungsdauer und Methioningehalt der Diät (0,4 % Methionin für 4 Wochen) an eine mögliche Fehlernährung des Menschen angepasst waren. Bei diesen Ratten war die Plasmahomocystein-Konzentration ca. 2-fach höher, als bei Ratten, die im gleichen Zeitraum eine "normale" Diät mit einem 3-4 fach niedrigeren Methioningehalt bekamen. Neben der Auswirkung der Diät auf den Homocystein-Stoffwechsel wurde geprüft, welche der in der Literatur dargestellten potentiellen Pathomechanismen für Hyperhomocysteinämie-induzierte Schäden Anwendung in diesem Modell finden. Obwohl die Konzentration von Homocystein im Plasma verändert war, wurde keine Beeinträchtigung der Gefäßfunktion gefunden. Auch die Plasmakonzentration von asymmetrischem Dimethylarginin, einem weiteren Risikoindikator für Herz-Kreislauf-Erkrankungen blieb unverändert, obwohl dieser Parameter bei Hyperhomocysteinämie oftmals erhöht ist. Eine Konzentrationsverdoppelung von Homocystein durch erhöhte alimentäre Methioninzufuhr ohne gleichzeitige Erhöhung von ADMA scheint also keine Verschlechterung der Gefäßfunktion bei Ratten zu bewirken. In diesem Punkt kann man von in anderen Modellen der Hyperhomocysteinämie gefundenen Resultaten keine Rückschlüsse auf die durch alimentäres Methionin verursachte Hyperhomocysteinämie ziehen. Andere Modelle zur Induktion einer Hyperhomocysteinämie ist Homocyst(e)in-Fütterung. In weiteren Rattenstudien wurden Effekte homocystin- und methioninreiche Diät verglichen. In diesen Studien zeigte sich, dass bei ähnlichen applizierten Dosen (tägliche Aufnahme ca. 1,0 bzw. 1,4 g/kg Körpergewicht) methionin- und homocystinreiche Diät bei Ratten zu vergleichbaren Plasma-Homocysteinspiegeln führen (methioninreich: 27,32 ± 2,80 µmol/l; homocystinreich: 40,61 ± 2,22 µmol/l). Als Vergleichsparameter zur Beurteilung pathophysiologischer Veränderungen diente zum einen der Gewebsgehalt an Homocystein, zum anderen wurden die intrazellulären Konzentrationen von S-Adenosyl-Methionin (SAM) und S-Adenosyl-Homocystein (SAH) betrachtet. Es zeigten sich besonders in Leber und Niere signifikante Unterschiede zwischen einer methioninreichen und einer homocystinreichen Diät bei Ratten. Dies ist eine mögliche Erklärung dafür, dass die bei vierwöchiger methioninreicher Diät gefundenen Ergebnisse nicht mit Literaturdaten übereinstimmen. Abschließend wurde der Frage nachgegangen, ob eine homocytinreiche Ernährung, wie in der vorherigen Studie angewandt, überhaupt möglich ist. Da zwar die Gehalte von Methionin in fast allen Lebensmitteln bekannt sind, nicht aber die von Homocystein, wurde untersucht, in welchen Konzentrationen Homocystein in Lebensmitteln enthalten ist. In Schwarzbier (0,03 mg/l), Weißbrot (0,95 mg/kg), Roquefort-Käse (0,50 mg/kg), Thunfisch (0,25 mg/kg) und Schweineleber (0,31 mg/kg) konnte Homocystein bestimmt werden. Da die Homocysteinkonzentrationen in diesen Beispiellebensmitteln mindestens um den Faktor 105 geringer waren als die Methioninkonzentrationen ist ein Einfluss von alimentärem Homocystein auf den Plasmaspiegel sehr unwahrscheinlich. Es wurde weiterhin geprüft, ob durch Darmbakterien ein Teil des alimentär aufgenommenen Methionins bereits im Dünndarm in Homocyt(e)in umgewandelt werden könnte. Dabei wurde eine vermehrte Homocysteinproduktion nach Methionin-Zugabe zu Dünndarmisolaten gefunden. Quantitativ kommt dieser Homocysteinquelle eine untergeordnete Bedeutung zu.
176

Genetic and nutritional folate deficiency : implications for homocystinuria and intestinal neoplasia

Sibani, Sahar. January 2000 (has links)
Folate deficiency, a prevalent vitamin deficiency in America, can stem from environmental and/or genetic causes. The most common inborn error of folate metabolism is deficiency of methylenetetrahydrofolate reductase (MTHFR), which catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. Severe MTHFR deficiency results in hyperhomocysteinemia and homocystinuria; patients present with developmental delay, and various neurological and vascular disorders. This thesis describes three mutations identified in the MTHFR locus in patients with severe deficiency: 1025T→C (M→T), 1027T→G (W→G), and 1768G→A (E→K). Genotype-phenotype correlations are described, along with biochemical characterization of three mutations (983A→G (N→S), 1025T→C, 1027T→G). All three mutations exert their effect by decreasing Vmax without changing the enzyme's affinity for its substrate, 5-methyltetrahydrofolate. The 983A→G variant also conferred decreased affinity for FAD, a cofactor. / The more common and mild deficiency observed in the general healthy population is probably due in part to insufficient dietary intake of folate. Folate deficiency has been associated with increased risk for colon cancer. In a pilot study presented here, the impact of altered folate intake on tumor multiplicity in the Min mouse, a model for multiple intestinal neoplasia, was assessed. Folate deficient diets did not produce a consistent change in tumor numbers. However, a linear correlation between S-adenosylmethionine and S-adenosylhomocysteine content of preneoplastic tissue and tumor multiplicity was identified. / This thesis contributes to our understanding of the impact of genetic- and/or dietary-induced folate deficiency on cellular and organismal functions.
177

Physical conditioning, total plasma homocysteine concentration and cardiovascular function in middle-aged men with coronary heart disease risk factors / Rumada Nel

Nel, Rumada January 2006 (has links)
Background: In the past 37 years, increased efforts have been directed toward a better understanding of the importance of Hcy in disease and it has now become clear that hyperhomocysteinemia is a major independent risk factor for CVD. Extensive research on the influence of vitamin supplementation leading to reductions in Hcy levels and improvements in cardiovascular function has been done. The importance of exercise in the lowering of cardiovascular risk factors, as well as its favourable influence on cardiovascular function has also been indicated in several studies, however, the limited number of studies investigating the effect of exercise on Hcy concentrations revealed contradicting results. Furthermore, a relationship between Hcy concentration and cardiovascular function with the intervention of an exercise training and a vitamin supplementation programme respectively has also not been investigated. Objective: The objective of this study was to examine the effect of a 12-week exercise training and a 12-week vitamin supplementation intervention respectively on tHcy concentrations and cardiovascular function, and whether the change in tHcy concentration within the different interventions correlated with the change in cardiovascular function. Methods: In a randomised controlled cross-over intervention study, 52 men matched for age, cardiorespiratory fitness levels and cardiovascular risk factors were randomly assigned to one of 3 groups (Group A = exercise training programme, 20-30min. at 70-80% of HRmax; Group B = 400 g folic acid and 25 g vitamin B12 supplement; Group C = control). Group A and B were crossed over for phase 11, and Group C remained the control. The questionnaires were completed, and the body composition variables (BMI, WHR and body fat percentage), cardiovascular function (Finometer), tHcy concentrations and VO2max, were measured before and after each 12-week intervention period. A 6-week washout period separated the crossovers. Results: The ANCOVA, adjusted for age and BMI, showed that the percentage change from baseline to end, corrected for baseline of the tHcy concentration increased significantly (p ≤ .05) by 9.7% with the exercise training intervention and decreased significantly (p ≤ .05) by 12.9%, with the vitamin supplementation intervention. The ANCOVA of the percentage change from baseline to end in cardiovascular function showed that the vitamin supplementation intervention resulted in improvements in cardiovascular function (decreased resting MAP, TPR and increased resting SV, CO, Cw) in comparison to the impairment in cardiovascular function with the exercise training intervention (increased resting DBP, MAP and TPR). The relationship between the tHcy concentration and cardiovascular function at baseline and within each of the different interventions were assessed by partial correlations adjusted for age, BMI and VO2max. Significant (p ≤ .05) relationships only occurred within the vitamin supplementation intervention, where decreased percentage change in tHcy concentration significantly correlated with increased percentage change of resting SV and CO and decreased percentage change of resting TPR. Conclusion: The general conclusion that can be drawn is that a 12-week vitamin supplementation intervention showed increased health related results, e.g. a significant reduction in tHcy concentration, an improvement in cardiovascular function and a significant positive relationship between these b o factors, in comparison to the 12-week exercise training intervention that significantly increased the tHcy concentration and did not show increased health related results. Due to inadequate compliance to the exercise training intervention, no conclusion can be drawn with regard to the effect of exercise training on tHcy concentrations and cardiovascular function. / Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2007
178

Prevalence of Hyperhomocysteinemia in Patients with Chronic Kidney Disease After Folic Acid Food Fortification of the Canadian Food Supply

Paterson, Linda Jane 31 May 2011 (has links)
Elevated plasma total homocysteine (ptHcy) or hyperhomocysteinemia (hHcy) independently predicts cardiovascular disease in predialysis chronic kidney disease (pCKD). Folate status is one of the known nutritional determinants of ptHcy. In the era of folic acid food fortification, this cross-sectional study aimed to describe in pCKD subjects (n=48): 1) Prevalence of hHcy. 2) Intake and status of nutrients involved in homocysteine metabolism. 3) Determinants of ptHcy. The prevalence of hHcy was 93.8% (95% CI: 81.8 to 98.4). Median (25th, 75th percentile) total folate intake from food and supplements was 389 (282,640) µg DFE/d. No subject was folate deficient (red blood cell < 317 nmol/L). Red blood cell folate (r = - 0.406, p=0.004) and energy-protein undernutrition (r = 0.357, p=0.013) independently predicted ptHcy. To conclude, total folate intake among subjects with pCKD was sufficient to prevent folate deficiency but not able to prevent a high prevalence of hHcy.
179

Prevalence of Hyperhomocysteinemia in Patients with Chronic Kidney Disease After Folic Acid Food Fortification of the Canadian Food Supply

Paterson, Linda Jane 31 May 2011 (has links)
Elevated plasma total homocysteine (ptHcy) or hyperhomocysteinemia (hHcy) independently predicts cardiovascular disease in predialysis chronic kidney disease (pCKD). Folate status is one of the known nutritional determinants of ptHcy. In the era of folic acid food fortification, this cross-sectional study aimed to describe in pCKD subjects (n=48): 1) Prevalence of hHcy. 2) Intake and status of nutrients involved in homocysteine metabolism. 3) Determinants of ptHcy. The prevalence of hHcy was 93.8% (95% CI: 81.8 to 98.4). Median (25th, 75th percentile) total folate intake from food and supplements was 389 (282,640) µg DFE/d. No subject was folate deficient (red blood cell < 317 nmol/L). Red blood cell folate (r = - 0.406, p=0.004) and energy-protein undernutrition (r = 0.357, p=0.013) independently predicted ptHcy. To conclude, total folate intake among subjects with pCKD was sufficient to prevent folate deficiency but not able to prevent a high prevalence of hHcy.
180

Development of dementia in mild cognitive impairment (MCI) patients with focus on B-vitamins /

Annerbo, Sylvia, January 2007 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Page generated in 0.0349 seconds