RESUMO
Adverse effects of lead (Pb) on human health are observed even at levels below 5 µg/dL, affecting principally the children population and suggesting that there is not a safe exposure level. The determination of Pb isotopic ratios (LIRs) in biological and environmental samples, is an appropriate tool to track and control the exposure sources, because LIRs constitutes the pollutant's isotopic signature and hence can be used to identify sources of Pb emission. This study proposes the optimization of a method in order to significantly reduce the biological samples' matrix interferences, and improves precision and accuracy in the measurements of LIRs. Four total blood digestion methods were evaluated and the results were subjected to statistical methods (ANOVA) determining the combination of HNO3:H2O2 (2:1 v v-1)/g from a sample on a hot plate as the best of them. For the method's validation, detection and quantification limits, linearity range, intermediate precision and recovery were evaluated. The total Pb (PbT) and LIRs were performed by ICP-QMS, defining the optimal value of detector dead time (DT), and correcting mass bias and instrumental drift for this matrix. LIRs based on 206Pb, 207Pb and 208Pb were determined at high precision (%RSD 0.03-0.49%), than those involving 204Pb (%RSD > 0.8). The optimized methodology can be used to identify pollution sources in blood and environmental samples using LIRs (206Pb/207Pb, 207Pb/208Pb, 208Pb/206Pb, etc.) in a trustworthy and simple way, with accurate results.
Assuntos
Monitoramento Ambiental/métodos , Poluentes Ambientais/efeitos adversos , Poluentes Ambientais/análise , Isótopos/efeitos adversos , Isótopos/sangue , Chumbo/efeitos adversos , Chumbo/sangue , Humanos , Espectrometria de Massas/métodosRESUMO
Concentrations of lead were assessed in the sea turtle, Lepidochelys olivacea, from a nesting colony of the Eastern Pacific. Twenty-five female turtles were sampled and a total of 250 eggs were collected during the "arribada" event of the 2005-2006 season. Considering the nesting season, the maternal transfer of lead (Pb) via egg-laying, in terms of metal burden in whole body, was 0.5%. Pb concentrations (in dry weight) in blood (0.95+/-0.18microgg(-1)) and egg samples (yolk, 0.80+/-0.10microg g(-1); albumen, 1.08+/-0.20microg g(-1); eggshell, 1.05+/-0.20microg g(-1)) were comparable or even lower than those found in other sea turtles. The isotope ratios ((206)Pb/(207)Pb and (206)Pb/(208)Pb) in blood (1.183+/-0.0006 and 2.452+/-0.0006, respectively) were comparable to that of natural Pb-bearing bedrock in Mexico (1.188+/-0.005 and 2.455+/-0.008, respectively). According to international norms of Pb, the health of this population and its habitats is acceptable for Pb and corresponds to basic levels of a nearly pristine environment.
Assuntos
Chumbo/metabolismo , Óvulo/metabolismo , Tartarugas/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Biometria , Monitoramento Ambiental , Feminino , Isótopos/sangue , Isótopos/metabolismo , Chumbo/sangue , Troca Materno-Fetal , Oceano Pacífico , Água do Mar/química , Tartarugas/sangue , Poluentes Químicos da Água/sangueRESUMO
Ex-situ BNCT for multifocal unresectable liver metastases employing whole or partial autograft techniques requires knowledge of boron concentrations in healthy liver and metastases following perfusion and immersion in Wisconsin solution (W), the procedure employed for organ preservation during ex-situ irradiation. Measurements of boron concentration in blood, liver and metastases following an intravenous infusion of BPA-F in five colorectal liver metastases patients scheduled for surgery were performed. Tissue samples were evaluated for boron content pre and post perfusion and immersion in W. Complementary histological studies were performed. The data showed a dose-dependent BPA uptake in liver, a boron concentration ratio liver/blood close to 1 and a wide spread in the metastases/liver concentration ratios in the range 0.8-3.6, partially attributable to histological variations between samples. Based on the boron concentrations and dose considerations (liver < or =15 Gy-Eq and tumor> or =40 Gy-Eq) at the RA-3 thermal neutron facility (mean flux of about (6+/-1) x 10(9) n cm(-2)s(-1)), ex-situ treatment of liver metastases at RA-3 would be feasible.
Assuntos
Adenocarcinoma/metabolismo , Adenocarcinoma/secundário , Boro/farmacocinética , Neoplasias Colorretais/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/secundário , Adenocarcinoma/radioterapia , Adenocarcinoma/cirurgia , Idoso , Argentina , Boro/sangue , Compostos de Boro/administração & dosagem , Compostos de Boro/farmacocinética , Compostos de Boro/uso terapêutico , Terapia por Captura de Nêutron de Boro , Feminino , Humanos , Técnicas In Vitro , Infusões Intravenosas , Isótopos/sangue , Isótopos/farmacocinética , Fígado/metabolismo , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/cirurgia , Transplante de Fígado , Masculino , Pessoa de Meia-Idade , Fenilalanina/administração & dosagem , Fenilalanina/análogos & derivados , Fenilalanina/farmacocinética , Fenilalanina/uso terapêutico , Radiossensibilizantes/administração & dosagem , Radiossensibilizantes/farmacocinética , Radiossensibilizantes/uso terapêutico , Distribuição Tecidual , Transplante AutólogoRESUMO
A new approach to determine the tumor-to-blood (10)B concentration ratio in boron neutron capture therapy (BNCT) is introduced. It is a statistical method, which uses maximum likelihood estimation on the clinical outcome of a BNCT treatment. Its performance is shown in a clinical case of cutaneous multiple nodular melanomas. The calculations involve a detailed dosimetry analysis, the determination of tumor control probabilities for the different nodules, the maximum likelihood estimation itself, and a parametric bootstrap to obtain confidence intervals for the tumor-to-blood ratio. The obtained ratio is 3.05 +/- 0.46 with a 95%-confidence interval. These results are consistent with those found in literature. Moreover, a single patient with multiple nodules proves enough to get statistically relevant results. The proposed method does not involve surgery and can be performed after a BNCT treatment without being invasive for the patient.