Are fingernail lead levels a reliable biomarker of lead internal dose?

BACKGROUND: Potentially toxic elements, such as lead, can bioaccumulate and alter human physiology. Human biomonitoring is an essential tool to evaluate chemical exposures in different biological matrices (blood, urine, saliva, nails, and hair). Of these biological matrices, nails are favorable for their ease of sampling, transport and storage. The aim of this study was to investigate possible correlations between blood lead levels (BLL) and washed and non-washed fingernail lead levels (FLL) in 55 adults living in a lead-contaminated area. METHOD: Venous blood and fingernail (thumbs and forefingers) samples were collected. Nails from the left hand were washed with Triton X-100 (0.5 % m/v) and HNO3 solution, while nails from the right hand were not submitted to the pre-analytical procedures. Samples were analyzed by graphite furnace atomic absorption spectrometry, and pairwise correlations were used to correlate lead concentrations between BLL and FLL; nails from fingers of the same hand and between washed and unwashed fingernails. Principal component analysis was performed and scatter diagrams were plotted to investigate correlations. RESULTS: A non-significant positive correlation was found between BLL and washed forefinger nails lead (r = 0.219, p = 0.112) and between BLL and thumbnail lead levels (r = 0.182, p = 0.191). Comparison of fingernails from the same hand (thumb and forefinger), showed that lead concentrations of non-washed nails varied widely, even on analyses of transversal fragments from the same nail. Lead levels in non-washed forefinger nails were not correlated with non-washed thumbnails (r = 0.169, p = 0.219). Conversely, washed thumb and forefinger nails were found to be correlated (r = 0.39, p = 0.003). Washed and non-washed nails were also found to be correlated (p < 0.0001). CONCLUSION: In conclusion, the results showed that non-washed nails are not a reliable biomarker for lead exposure. Although washing nails before analysis may reduce external contamination, the correlation of lead concentrations between fingers is poor for fingernail lead levels to serve as an internal dose biomarker to lead exposure. In addition, levels in washed nails were not significantly correlated with blood lead levels. Fingernail lead levels seem to serve as an indicator of lead exposure sources in contact with the individual, but not as a reliable biomarker of internal dose.

Assessment of physical activity intensity and duration in the paediatric population: evidence to support an a priori hypothesis and sample size in the agreement between subjective and objective methods.

We aimed to provide evidence for an a priori hypothesis and sample size for subjectively assessing physical activity intensity and duration in paediatric population, adopting objective methods as the reference. We searched electronic databases, reference lists and author databases. Correlation coefficients were pooled as an indicator of agreement estimates. We found 183 agreement analyses (94.5% based on correlation coefficients) from 89 studies that met our inclusion criteria. We identified four physical activity parameters addressing intensity and two parameters addressing duration. The physical activity parameters focusing on intensity were measured only by questionnaires, and the best correlation was achieved by moderate-to-vigorous physical activity compared with a heart rate monitor. In addition, total physical activity duration had a stronger correlation with an accelerometer when measured by diaries or logs than when measured by questionnaires. In both cases, the correlation was moderate. Studies with sample sizes between 50 and 99 subjects showed measurements that were stable in both magnitude and interpretation. Our findings suggest that the agreement between subjective and objective methods for assessing physical activity intensity and duration is weak to moderate. Furthermore, sample sizes ranging from 50 to 99 subjects provide stable agreement estimates between methods.

Atividade alelopática de extratos aquosos de plantas medicinais na germinação de Lactuca sativa L. e Bidens pilosa L. / Allelopathic activity of aqueous extracts of medicinal plants on the germination of Lactuca sativa L. and Bidens pilosa L.

O potencial alelopático de quatro diferentes extratos de plantas medicinais (Eclipta alba, Gomphrena globosa, Tabernaemontana catharinensis e Tithonia diversifolia) foi avaliado na germinação de Bidens pilosa e Lactuca sativa. Dentre os resultados obtidos no teste de germinação, notou-se um maior poder inibitório do extrato de G. globosa sobre sementes e plântulas de Bidens pilosa e Lactuca sativa independente da concentração utilizada e aumento da atividade inibitória de extratos T. catharinensis e de T. diversifolia com aumento da concentração destes. Quanto ao Índice de Velocidade de Germinação, os dados demonstraram redução do índice devido a elevada mortalidade das plântulas submetidas aos extratos de G. globosa e de T. catharinensis e a germinação tardia das sementes submetidas ao extrato de T. diversifolia. Quanto ao vigor das sementes, as menores porcentagens de sobrevivência ocorreram extratos à 2,5 por cento para B. pilosa e 10 por cento para L. sativa.

The allelopathic potential of four different extracts of medicinal plants (Eclipta alba, Gomphrena globosa, Tabernaemontana catharinensis and Tithonia diversifolia) was evaluated on the germination of Bidens pilosa and Lactuca sativa. The results obtained in the germination test indicated a greater inhibitory activity of G. globosa extract on Bidens pilosa and Lactuca sativa seeds and seedlings, regardlessof the used concentration, and an increase in the inhibitory activity of T. catharinensis and T. diversifolia extracts with an increase in their concentrations. As to Germination Speed Index, the data demonstrated a reduction due to the high mortality of seedlings subjected to G. globosa and T. catharinensis extracts and a late germination of seeds subjected to T. diversifolia extracts. As to the vigor of seeds, the smallest survival percentages occur at 2.5 percent for B. pilosa and at 10 percent for L.sativa.

Treatment for recurrent hepatitis C virus infection after liver transplantation.

Cirrhosis due to hepatitis C virus (HCV) infection is the current leading indication for orthotopic liver transplantation (OLT) in the world. This series reports our program's experience with the treatment of HCV infection after the development of histological hepatitis. Between March 2002 and June 2008, patients with recurrent HCV were selected for treatment if the liver biopsy showed at least the F2 degree of Metavir score. HCV viral load was measured at 4, 12 and 24 weeks as well as at the end of treatment and at 6 months thereafter for patients who became HCV RNA negative (sustained virological response [SVR]). In this period, we performed 287 liver transplantations in 279 patients, including 117 (42%) who had HCV cirrhosis as the indication for OLT of whom 25 were eligible for antiviral treatment. Twelve patients completed treatment, 7 remain on treatment, and 6 were discontinued. The principal collateral effect was anemia. Only 1 patient had an episode of acute cellular rejection, which responded to adjustment of immunosuppression. Antiviral treatment in transplanted patients was feasible and did not seem to induce severe immunological effects. Adjuvant therapies to reduce cytopenias are frequently required, principally erythropoietin. The best results were observed with the pegylated interferon alfa (PEG) plus ribavirin (RBV) group: 38.9% of SVR. We recommend antiviral treatment of eligible patients with confirmed HCV recurrence using PEG plus RBV.

Peat as a natural solid-phase for copper preconcentration and determination in a multicommuted flow system coupled to flame atomic absorption spectrometry.

The physical and chemical characteristics of peat were assessed through measurement of pH, percentage of organic matter, cationic exchange capacity (CEC), elemental analysis, infrared spectroscopy and quantitative analysis of metals by ICP OES. Despite the material showed to be very acid in view of the percentage of organic matter, its CEC was significant, showing potential for retention of metal ions. This characteristic was exploited by coupling a peat mini-column to a flow system based on the multicommutation approach for the in-line copper concentration prior to flame atomic absorption spectrometric determination. Cu(II) ions were adsorbed at pH 4.5 and eluted with 0.50 molL(-1) HNO(3). The influence of chemical and hydrodynamic parameters, such as sample pH, buffer concentration, eluent type and concentration, sample flow-rate and preconcentration time were investigated. Under the optimized conditions, a linear response was observed between 16 and 100 microgL(-1), with a detection limit estimated as 3 microgL(-1) at the 99.7% confidence level and an enrichment factor of 16. The relative standard deviation was estimated as 3.3% (n=20). The mini-column was used for at least 100 sampling cycles without significant variation in the analytical response. Recoveries from copper spiked to lake water or groundwater as well as concentrates used in hemodialysis were in the 97.3-111% range. The results obtained for copper determination in these samples agreed with those achieved by graphite furnace atomic absorption spectrometry (GFAAS) at the 95% confidence level.

Multielement electrothermal atomic absorption spectrometry: a study on direct and simultaneous determination of chromium and manganese in urine.

A study was carried out on the direct determination of Cr and Mn in urine using simultaneous atomic absorption spectrometry (SIMAAS). The heating program conditions, the absorbance signal profiles, the influence of different chemical modifiers, and the urine sample volume delivery into the tube were optimized to perform the calibration with aqueous solutions. Among several chemical modifiers tested, the best recovery and repeatability results were obtained for 3 microg Mg(NO3)2. On using this modifier, the pyrolysis and atomization temperatures for simultaneous determination of Cr and Mn were 1,300 degrees C and 2,500 degrees C, respectively. Urine samples were diluted (1+1) with 2.0% (v/v) HNO3 + 0.05% (w/v) Triton X-100 prepared in high purity water. A 20-microL aliquot of analytical solution and 10 microL of chemical modifier solution were delivered to the graphite tube. The characteristic masses were 7.8 pg for Cr (RSD=4.0%) and 4.6 pg for Mn (RSD=2.6%). The limits of detection were 0.08 microg L(-1) (n=20, 3s) for Cr and 0.16 microg L(-1) (n=20, 3s) for Mn. Recovery studies for 1.0 or 2.5 microg L(-1) of Cr and Mn added to different urine samples showed acceptable results for Cr (100%, RSD=14%) and Mn (88%, RSD=5.6%).

Atomization of Al in a tungsten coil electrothermal atomic absorption spectrophotometer.

Electrothermal atomic absorption spectrophotometry of Al in a tungsten coil atomizer was evaluated and applied for its determination in hemodialysis fluid. The system was mounted on a Varian Spectra AA-40 spectrophotometer with continuum background correction and all measurements, in peak height absorbance, were done at 309.3 nm. The purge gas was a mixture of 90% Ar plus 10% H(2). Observation height, gas flow, drying, pyrolysis and atomization steps were optimized. The heating program was carried out by employing a heating cycle in four steps: dry, pyrolysis, atomization and clean. The determination of Al in hemodialysis solutions was performed by using a matrix-matching procedure. Al in hemodialysis solutions was determined by TCA and by electrothermal atomization with a graphite tube atomizer. There is no differences between results obtained by both methods at a confidence level of 95%. The characteristic mass of Al by using the TCA was 39 pg and the detection limit was 2.0 mug l(-1).