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Rapid, sensitive and simultaneous determination of ascorbic and uric acids in human plasma by ion-exclusion HPLC-UV

Publication . Ferin, Rita; Pavão, Maria Leonor; Baptista, José

OBJECTIVES: Ascorbic (AA) and uric (UA) acids act as antioxidants and are capable to react with biologically relevant oxidants. We aimed to developed a simple, rapid, sensitive, and accurate ion-exclusion HPLC-UV methodology for the simultaneously determination of AA and UA in human plasma. METHODS: Analytical pre-requisites, such as the use of heparin as an anticoagulant and meta-phosphoric acid as a stabilizer were added for accurate and reliable measurements. Chromatographic separation was achieved by an isocratic elution on a HEMA-BIO 1000 SB analytical column using a phosphate buffer, pH 2.4, as a mobile phase. RESULTS: Results indicated an excellent linearity with correlation coefficients (r²) ≥ 0.999. The LOD of AA and UA was 1.02 and 1.42 nmol/mL, respectively, while LOQ ranged from 0.306 to 0.426 nmol/mL. A great repeatability for both antioxidants was found, where the CV (%) values for intra-day were lower than 1.8% and under 6.5% for the inter-day assay. The recovery of AA ranged from 92% to 96% and from 99% to 100% for UA. CONCLUSION: This validated method allows the determination of both antioxidants within 10 min, and is well suited to routine measurements and/or high-throughput clinical analysis. The methodology was applied to assess the antioxidant status of a group of Azorean subjects.

2013-05Journal article

Open access

Cross-sectional study of risk factors for atherosclerosis in the Azorean population

Publication . Cymbron, Teresa; Raposo, Mafalda; Kazachkova, Nadia; Bettencourt, Conceição; Silva, Francisca; Santos, Cristina; Dahmani, Yahya; Lourenço, Paula C.; Ferin, Rita; Pavão, Maria Leonor; Lima, Manuela

Background: Atherosclerosis -a major cause of vascular disease, including ischemic heart disease (IHD), is a pathology that has a two-fold higher mortality rate in the Azorean Islands compared to mainland Portugal. Aim: This cross-sectional study investigated the role of genetic variation in the prevalence of atherosclerosis in this population. Subjects and methods: A total of 305 individuals were characterized for polymorphisms in eight susceptibility genes for atherosclerosis: ACE, PAI1, NOS3, LTA, FGB, ITGB3, PON1 and APOE. Data were analysed with respect to phenotypic characteristics such as blood pressure, lipid profile, life-style risk factors and familial history of myocardial infarction. Results: In the total sample, frequencies for hypercholestrolemic, hypertensive and obese individuals were 63.6%, 39.3% and 23.3%, respectively. The genetic profile was similar to that observed in other European populations, namely in mainland Portugal. No over-representation of risk alleles was evidenced in this sample. Conclusions: One has to consider the possibility of an important non-genetic influence on the high cholesterolemia present in the Azorean population. Since diet is the most important life-style risk factor for dyslipidemia, studies aiming to evaluate the dietary characteristics of this population and its impact on serum lipid levels will be of major importance.

2011Journal article

Open access

Plasma aminothiol profile and some of its determinants in apparently Azorean subjects

Publication . Lima, Ana; Ferin, Rita; Baptista, José; Pavão, Maria Leonor

OBJECTIVES. To evaluate the plasma aminothiol profile (PAP) and serumgamma-glutamyltransferase (GGT) activity, aswell as plasma folate, vitamin B12, and vitamin B6 concentrations, in 326 apparently healthy subjects from the Azores archipelago (Portugal). Also eventual relationships of PAP with conventional risk factors for atherosclerosis were investigated, aiming at the finding of early blood markers of the disease. DESIGN AND METHODS.This was an observational cross-sectional study, where participants were split into two groups: one with a normal and another with an altered PAP (at least one aminothiol out of its reference concentration range). RESULTS. About 76% of subjects had an altered PAP, mainly due to low glutathione levels (<1.5 μmol/L), mostly associated with normal GGT activity. Prevalence of hyperhomocysteinemia was 10%, where only 33% had some B-vitamin deficiency. The risk for atherosclerosis wasmore evidenced in subjects exhibiting both deficient GSH concentration and increased serum GGT activity. CONCLUSIONS. An altered PAP, namely, when caused by low GSH levels in the absence of alterations in the Hcy, or Cys, or Cys-Gly concentrations and in serum GGT activity, might reveal a subclinical stage of atherogenesis and should be explored as a potential early marker of atherosclerosis.

2014Journal article

Open access