A new automated method for the determination of the Total Antioxidant Capacity (TAC) of human plasma, based on the crocin bleaching assay

BACKGROUND: Antioxidant molecules, which scavenge free radical species to prevent or delay oxidative damage of important macromolecules, membrane lipids and lipoproteins, are prevalent in plasma and other biological fluids. Among them, bilirubin, uric acid and protein thiols are the major endogenous antioxidants, while vitamins C and E, as well as a number of food-derived (poly)aromatic substances, belonging to stilbens, flavonoids and phenolic acids, are the main classes of nutritional antioxidants. Assays for total antioxidant capacity in plasma differ in their type of oxidation source, target and measurement used to detect the oxidized product. METHODS: In the present work we present an automated assay for the estimation of blood total antioxidant capacity (TAC assay), based on the crocin bleaching (oxidation) method. This method was adapted on a modern autoanalyzer, was linear over a wide range of values (0–3 mmol/L), and performed using an end point measurement. RESULTS: The TAC method presented a linear correlation with another automated commercial Total Antioxidant Status (TAS) test. Detection of the interference of different metabolites revealed a significant participation of TAC from uric acid, bilirubin, albumin, a minor interference from ascorbic acid, and no interference from hemoglobin. TAC was not modified by two freeze/thawing cycles, and was stable in samples stored at room temperature for 4 hours. K-EDTA and heparin were the best anticoagulants, while citrate decreased TAC by 20%. Reference values derived from samples of normal blood donors was 1.175 ± 0.007 mmol/L (mean ± SEM), while a diet rich in antioxidants more than doubled this value. CONCLUSIONS: The proposed TAC assay, is fully automated, stable and reliable, and could be of value in the estimation of the AC of plasma. It is further proposed to calculate the antioxidant capacity of plasma after a subtraction of all interference deriving from endogenous and/or exogenous metabolites. The antioxidant capacity of plasma thus calculated can be used as a useful indicator of the antioxidant value of foods and beverages in the daily diet

Total and corrected antioxidant capacity in hemodialyzed patients

BACKGROUND: Oxidative stress may play a critical role in the vascular disease of end stage renal failure and hemodialysis patients. Studies, analyzing either discrete analytes and antioxidant substances, or the integrated total antioxidant activity of human plasma during hemodialysis, give contradictory results. METHODS: Recently, we have introduced a new automated method for the determination of Total Antioxidant Capacity (TAC) of human plasma. We have serially measured TAC and corrected TAC (cTAC: after subtraction of the interactions due to endogenous uric acid, bilirubin and albumin) in 10 patients before the onset of the dialysis session, 10 min, 30 min, 1 h, 2 h and 3 h into the procedure and after completion of the session. RESULTS: Our results indicate that TAC decreases, reaching minimum levels at 2 h. However, corrected TAC increases with t(1/2 )of about 30 min. We then repeated the measurements in 65 patients undergoing dialysis with different filters (36 patients with ethylene vinyl alcohol copolymer resin filter -Eval-, 23 patients with two polysulfone filters -10 with F6 and 13 with PSN140-, and 6 patients with hemophan filters). Three specimens were collected (0, 30, 240 min). The results of this second group confirm our initial results, while no significant difference was observed using either filter. CONCLUSIONS: Our results are discussed under the point of view of possible mechanisms of modification of endogenous antioxidants, and the interaction of lipid- and water-soluble antioxidants

Evaluation of the accuracy of the determination of lead isotope ratios in wine by ICPMS using quadrupole, multicollector magnetic sector and time-of-flight analyzers

International audienceDifferent mass analysers [(quadrupole (Q), time-of-flight (TOF) and multicollector (MC) sector-field (SF)] of ions produced in an inductively coupled plasma were evaluated for the determination of lead isotope ratios in wine samples. A population of 20 wines of different origin including two reference wines from the EC Standards, Measurement and Testing Programme with concentrations varying between 7-140 ?g Pb l-1 was investigated. Wines were analyzed directly by Q ICP MS and MC ICP MS. The poor sensitivity of the TOF instrument, further aggravated by matrix signal suppression, did not allow the acquisition of data for wine samples that contained less than 50 ?g l-1 in the direct sample introduction mode. The separation and preconcentration of lead were therefore required. The precision obtained for the 206Pb/207Pb and 208Pb/206Pb were similar and equal to 0.14-2.7% for Q ICP MS, 0.04-0.17% for TOF ICP MS and 0.01-0.12% for MC ICP MS. The precision for 206Pb/204Pb was 0.44-5.29, 0.15-1.7, 0.08-1.6%, respectively. On the level of accuracy, the data from TOF ICP MS and MC ICP MS were in good agreement. The accuracy of Q ICP MS data was judged satisfactory in comparison with the other techniques but their poor precision was a significant obstacle on the way of using these data for the determination of the geographic origin of wine. © 2001 Elsevier Science B.V

Bioavailable 87Sr/86Sr in different environmental samples — Effects of anthropogenic contamination and implications for isoscapes in past migration studies

87Sr/86Sr reference maps (isoscapes) are a key tool for investigating past human and animal migrations. However, there is little understanding of which biosphere samples are best proxies for local bioavailable Sr when dealing with movements of past populations. In this study, biological and geological samples (ground vegetation, tree leaves, rock leachates, water, soil extracts, as well as modern and archeological animal teeth and snail shells) were collected in the vicinity of two early medieval cemeteries (“Thuringians”, 5–6th century AD) in central Germany, in order to characterize 87Sr/86Sr of the local biosphere. Animal tooth enamel is not appropriate in this specific context to provide a reliable 87Sr/86Sr baseline for investigating past human migration. Archeological faunal teeth data (pig, sheep/goat, and cattle) indicates a different feeding area compared to that of the human population and modern deer teeth 87Sr/86Sr suggest the influence of chemical fertilizers. Soil leachates do not yield consistent 87Sr/86Sr, and 87Sr/86Sr of snail shells are biased towards values for soil carbonates. In contrast, water and vegetation samples seem to provide the most accurate estimates of bioavailable 87Sr/86Sr to generate Sr isoscapes in the study area. Long-term environmental archives of bioavailable 87Sr/86Sr such as freshwater bivalve shells and tree cores were examined in order to track potential historic anthropogenic contamination of the water and the vegetation. The data obtained from the archeological bivalve shells show that the modern rivers yield 87Sr/86Sr ratios which are similar to those of the past. However, the tree cores registered decreasing 87Sr/86Sr values over time towards present day likely mirroring anthropogenic activities such as forest liming, coal mining and/or soil acidification. The comparison of 87Sr/86Sr of the Thuringian skeletons excavated in the same area also shows that the vegetation samples are very likely anthropogenically influenced to some extent, affecting especially 87Sr/86Sr of the shallow rooted plants

Consumo de Camellia sinensis em população de origem oriental e incidência de doenças crônicas Camellia sinensis consumption by an Asian-Brazilian population and incidence of chronic diseases

Investigar os prováveis benefícios dos hábitos culturais orientais, incluindo o consumo de Camellia sinensis (chá verde) na prevenção de doenças crônicas. Trinta e quatro indivíduos entre 25 e 84 anos, de ambos os sexos, pertencentes à comunidade nipônica do Rio de Janeiro, RJ, foram submetidos a anamnese alimentar e questionário socio-econômico-cultural. Dos indivíduos, 76% consumiam chá verde, sendo que 35% o ingeriam diariamente e 27% esporadicamente. Verificou-se que o consumo regular de álcool era predominante nos não usuários de chá verde, quando comparados com os apreciadores da bebida (50% e 35%, respectivamente, faziam uso de álcool). Não foi observado sedentarismo na amostra. Dos apreciadores do chá, 81% não apresentavam doenças crônicas. Já entre os consumidores, observamos um menor percentual de doenças crônicas, especialmente, de hipertensão, porém sem significância estatística.<br>To investigate the probable benefits of Asian dietary habits, including the intake of Camellia sinensis (green tea), in preventing chronic-degenerative diseases. Thirty-four individuals aging from 25 to 84 years from a Japanese community in Rio de Janeiro answered a socioeconomic-cultural questionnaire. Seventy-six percent of the individuals consumed green tea, where 35% consumed it daily and 27% consumed it sporadically. The regular intake of alcohol predominated among the non-consumers of green tea, when compared with green tea consumers (50% and 35%, respectively consumed alcoholic beverages). None of the individuals in the sample had a sedentary lifestyle. Among the individuals who consumed green tea, 81% did not have any chronic illnesses. The consumers of tea presented a lower incidence of chronic diseases, especially hypertension, but it was not statistically significant