Evaluation of MTHFR C677T gene polymorphism and homocysteine level in coronary atherosclerotic disease

OBJECTIVE: The aim of this study is to determine the prevalence of C677T methylenetetrahydrofolate reductase (MTHFR) polymorphism and correlate it with plasma homocysteine levels in coronary artery disease (CAD). METHODS: Ninety-three patients with documented CAD from Hospital Universitário Oswaldo Cruz (Recife, PE, Brazil) and 108 healthy controls were evaluated. Homocysteine and folate levels were determined by HPLC and chemoluminescence, respectively, and lipid profile was considered. Genotyping was done by RFLP/PCR. RESULTS: The groups were homogeneous for the C677T polymorphisms. The homocysteine level in cases (11.7 µmol/L) was statistically different from that observed in controls (8.84 µmol/L, p< 0.05). It was also observed that 72% of the patients had homocysteine values above12 µmol/L while the control group presented only 32% in this range. There was no relationship between homozigosity for the C677T polymorphism and the homocysteine level (p= 0.634). We noticed statistical differences between folate levels from patients and controls (6.22 and 7.69 ng/dL, p< 0.05, respectively). However, there was no correlation between homocysteine and folate concentrations in the entire group (r= -0.202). Comparing cases and controls, the odds ratio (OR) when homocysteine is high and folate is low was OR= 11.9; CI 95%= 4.16-34.42, p< 0.01. CONCLUSION: A lack of correlation between C677T mutation and homocysteine level suggests that environmental factors and others genetic factors seem to exert more influence on homocysteine level in this population.OBJETIVO: O objetivo deste trabalho é determinar a prevalência do polimorfismo C677T do gene metilenotetraidrofolato redutase (MTHFR) e associá-la com a concentração plasmática de homocisteína plasmática na doença arterial coronariana (DAC). MÉTODOS: Foram avaliados 93 pacientes com DAC documentada, atendidos no Hospital Universitário Oswaldo Cruz (Recife, PE, Brasil), e 108 controles sem a doença. Foram determinados os perfis lipídicos de pacientes e controles. As concentrações plasmáticas de homocisteína e folato foram determinadas por HPLC e quimioluminescência, respectivamente. A genotipagem foi realizada por RFLP/PCR. RESULTADOS: Os grupos de pacientes e controles foram homogêneos quanto aos perfis genéticos do polimorfismo investigado. Nos pacientes, as concentrações plasmáticas médias de homocisteina (11,7 ± 4,4 µmol/L) e de folato (6,22 ± 3,0 ng/dL) foram estatisticamente diferentes daquelas observadas nos controles (8,84 ± 3,2 µmol/L e 7,69 ± 3,1 ng/dL, respectivamente), ao nível de significância de 0,05. Entretanto, não houve correlação entre concentração plasmática de homocisteína e folato nos pacientes (r= -0,202). Não foi observada associação entre a homozigosidade 677TT para MTHFR e a concentração plasmática de homocisteína sérica (p= 0,634). A comparação dos casos e controles que apresentaram simultaneamente alta concentração plasmática de homocisteína e baixa concentração de folato, resultou numa razão de chance superior à de cada variável analisada independentemente (RC= 11,9; IC 95%= 4,16-34,42, p< 0,01). CONCLUSÕES: A mutação C677T não parece ser um fator genético importante capaz de explicar a hiperhomocisteinemia moderada observada nos pacientes com DAC. Outros fatores, ambientais e genéticos, devem ser investigados.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo (UNIFESP) Departamento de Pediatria Laboratório de Erros Inatos de MetabolismoUniversidade de Pernambuco ICB Departamento de Ciências FisiológicasUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Hospital das ClínicasUNIFESP, Depto. de Pediatria Laboratório de Erros Inatos de MetabolismoSciEL

A importância do uso de filtros, durante a infusão de nutrições parenterais adicionadas de emulsões lipídicas

Nutrições parenterais com adicionamento de emulsões lipídicas podem apresentar alterações físico-químicas, caracterizadas pela formação de precipitados amorfos ou cristalinos, bem como pelo aumento do tamanho das gotículas de gordura que se agregam. A verificação macroscópica dessas alterações nem sempre é possível, tendo em vista o aspecto opaco das emulsões. Utilizando-se estudo in vitro, este trabalho teve como objetivo evidenciar a presença de precipitados de fosfato de cálcio, de gotículas de gordura da emulsão lipídica com diâmetros superiores aos de hemácias, em nutrições parenterais, e a importância do uso de filtros na retenção dos mesmos. Esses eventos foram demonstrados por meio de inspeção macroscópica e microscópica, em nutrições parenterais contendo fosfato dibásico de potássio e de gluconato de cálcio, como fonte de fósforo e de cálcio, respectivamente, adicionados à mistura de soluções de aminoácidos a 10% p/v, com glicose a 50% p/v, emulsão lipídica a 20% p/v e minerais em diferentes proporções. Os resultados mostraram presença de precipitado de cálcio e de gotículas de gordura aumentadas e/ou agregadas antes da filtração, e ausência dos mesmos imediatamente após. Conclusão: o uso de filtros com poros de 1,2 mm foi capaz de reter precipitados e de impedir a passagem das gotículas de gordura com dimensões tais que pudessem causar embolias microvasculares em pacientes submetidos à nutrição parenteral.Parenteral nutrition preparations supplemented with lipid emulsions may present physicochemical alterations characterized by the formation of amorphous or crystalline precipitates and by an increased size of fat droplets, which aggregate. A macroscopic verification of these changes is not always possible because of the opaque aspect of the emulsions. The objective of the present in vitro study was to determine the presence of calcium phosphate precipitates, of fat droplets of the lipid emulsion with wider diameters than red blood cells in parenteral nutrition preparations and the importance of the use of filters for the retention of suchprecipitates. These events were demonstrated by macroscopic and microscopic inspection of parenteral nutrition preparations containing potassium dibasic phosphate and calcium gluconate as a source of phosphorus and calcium, respectively, added to the mixture of amino acid solutions at the proportion of 10% (w/v), with 50% glucose (w/v), a 20% lipid emulsion (w/v) and minerals at different proportions. The results showed the presence of a calcium precipitate and of enlarged and/or aggregated fat droplets before filtration, and their absence immediately after filtration. Conclusion:the use of filters with 1.2 mm pores was sufficient to retain the precipitates and to prevent the passage of fat droplets with dimensions that might cause microvascular embolism in patients submitted to parenteral nutrition

Effects of APOE, APOB and LDLR variants on serum lipids and lack of association with xanthelasma in individuals from Southeastern Brazil

Xanthelasma might be a clinical manifestation of dyslipidemia, a recognized risk factor for coronary artery disease. We investigated the association of apolipoprotein E (APOE HhaI), apolipoprotein B (APOB XbaI and Ins/Del) and LDL receptor (LDLR AvaII and HincII) gene polymorphisms with lipid profiles in 100 Brazilians with xanthelasma and 100 controls. Allele frequencies were similar in both groups. APOE, APOB and LDLR genotypes were not correlated with differences in the serum lipid profile. In individuals with xanthelasma, the APOB D allele was associated with less chance of having increased LDL-cholesterol (O.R. = 0.16, CI95% = 0.03-0.94, p = 0.042). In the control group, the APOB X+ allele was associated with less chance of having both increased total cholesterol (O.R. = 0.16, CI95% = 0.03-0.78, p = 0.023) and increased LDL-cholesterol (O.R. = 0.10, CI95% = 0.02-0.60, p = 0.012). Moreover, there was a significantly higher frequency of control individuals (68%) with elevated serum triglyceride levels, compared to patients (48%, p = 0.008). On the other hand, triglyceride levels in controls also seemed to be influenced by all other gene polymorphisms studied, an effect that might be enhanced by environmental factors