RESUMO
The present study investigated the integrated effects of several geochemical processes that control radium-226 ((226) Ra) mobility in the aquatic environment and bioaccumulation in in situ caged benthic invertebrates. Radium-226 bioaccumulation from sediment and water was evaluated using caged oligochaetes (Lumbriculus variegatus) deployed for 10 d in 6 areas downstream of decommissioned uranium operations in Ontario and Saskatchewan, Canada. Measured (226) Ra radioactivity levels in the retrieved oligochaetes did not relate directly to water and sediment exposure levels. Other environmental factors that may influence (226) Ra bioavailability in sediment and water were investigated. The strongest mitigating influence on (226) Ra bioaccumulation factors was sediment barium concentration, with elevated barium (Ba) levels being related to use of barium chloride in effluent treatment for removing (226) Ra through barite formation. Observations from the present study also indicated that (226) Ra bioavailability was influenced by dissolved organic carbon in water, and by gypsum, carbonate minerals, and iron oxyhydroxides in sediment, suggestive of sorption processes. Environmental factors that appeared to increase (226) Ra bioaccumulation were the presence of other group (II) ions in water (likely competing for binding sites on organic carbon molecules), and the presence of K-feldspars in sediment, which likely act as a dynamic repository for (226) Ra where weak ion exchange can occur. In addition to influencing bioavailability to sediment biota, secondary minerals such as gypsum, carbonate minerals, and iron oxyhydroxides likely help mitigate (226) Ra release into overlying water after the dissolution of sedimentary barite. Environ Toxicol Chem 2015;34:507-517. © 2014 SETAC.
Assuntos
Oligoquetos/metabolismo , Rádio (Elemento)/metabolismo , Urânio/metabolismo , Adsorção , Animais , Disponibilidade Biológica , Canadá , Monitoramento Ambiental , Sedimentos Geológicos/química , Minerais/análise , Oligoquetos/efeitos dos fármacos , Poluentes Químicos da Água/metabolismoRESUMO
BACKGROUND: Cytokine flow cytometry (CFC) provides a multiparameter alternative to ELISPOT assays for rapid quantitation of antigen-specific T cells. To increase the throughput of CFC assays, we have optimized methods for stimulating, staining, and acquiring whole blood or PBMC samples in 96-well or 24-well plates. RESULTS: We have developed a protocol for whole blood stimulation and processing in deep-well 24- or 96-well plates, and fresh or cryopreserved peripheral blood mononuclear cell (PBMC) stimulation and processing in conventional 96-well round-bottom plates. Samples from both HIV-1-seronegative and HIV-1-seropositive donors were tested. We show that the percent response, staining intensity, and cell recovery are comparable to stimulation and processing in tubes using traditional methods. We also show the equivalence of automated gating templates to manual gating for CFC data analysis. CONCLUSION: When combined with flow cytometry analysis using an automated plate loader and an automated analysis algorithm, these plate-based methods provide a higher throughput platform for CFC, as well as reducing operator-induced variability. These factors will be important for processing the numbers of samples required in large clinical trials, and for epitope mapping of patient responses.
Assuntos
Citocinas/análise , Citometria de Fluxo/métodos , Algoritmos , Automação , Criopreservação , Citometria de Fluxo/instrumentação , Citometria de Fluxo/normas , Corantes Fluorescentes , Humanos , Software , Linfócitos T/imunologia , Fatores de TempoRESUMO
Establishing exposure to contaminants within a given environment is often difficult for fish species with large home ranges. Chemical analyses of muscle or visceral tissue are useful indicators of recent exposure, but depuration, metabolic transformation, and tissue redistributions can alter temporal resolution. Otoliths are metabolically stable and thus provide complete chemical records within their calcified tissues that, when coupled to the annular structure, can provide temporal resolution for exposure to trace metals. Otoliths from bull trout, cutthroat trout, and mountain whitefish from an area rich in seleniferous soils and with active coal mining activity were analyzed for selenium to determine any history of exposure to elevated levels of selenium. Selenium concentrations in otolith primordia tended to be low, indicating that these fish emerged in low selenium areas. Later life stages showed peaks of high Se concentrations, suggesting that individuals moved into areas of increased selenium later in life. Individuals captured from the same area had a wide variety of selenium exposure profiles, indicating that these fish do not move en masse into and out of high-selenium areas. Year-to-year variability of selenium exposure patterns within an otolith suggests inconsistent utilization of high- and low-selenium areas by the individual. The inconsistent exposure profiles for these fish, in addition to their home range of tens of kilometres, indicate that soft tissue concentrations, while useful indicators of recent exposure, cannot be relied upon to provide a life history recording of exposure.
Assuntos
Minas de Carvão , Exposição Ambiental/análise , Membrana dos Otólitos/química , Salmonidae , Selênio/análise , Poluentes Químicos da Água/análise , Animais , Zinco/análiseRESUMO
Selenium (Se) is an essential micronutrient, exhibiting a narrow margin between nutritionally optimal and potentially toxic concentrations. Egg-laying vertebrates at the top of aquatic food chains are most at risk in environments with elevated aqueous Se concentrations. The Elk River watershed in British Columbia, Canada receives effluents containing Se from five coal mine operations. This study tested three hypotheses that might account for higher Se concentrations in fish from lentic compared to lotic habitats in the watershed: (1) enhanced uptake by aquatic primary producers, (2) longer food chain length, or (3) greater food web accumulation through sediment-detrital pathways. Stable isotope and Se concentration data demonstrated that Se concentrations in aquatic primary producers and food chain lengths were comparable in lentic and lotic habitats. Enhanced formation of organoselenium and subsequent uptake and cycling via sediment detrital pathways likely account for higher fish tissue Se concentrations in lentic than in lotic areas.
Assuntos
Cadeia Alimentar , Selênio/análise , Poluentes Químicos da Água/análise , Anfíbios , Animais , Colúmbia Britânica , Isótopos de Carbono , Meio Ambiente , Monitoramento Ambiental , Peixes , Sedimentos Geológicos/análise , Resíduos Industriais , Invertebrados , Mineração , Músculos/química , Isótopos de Nitrogênio , Plantas , Rios/química , Abastecimento de ÁguaRESUMO
To evaluate the potential clinical utility of a cytomegalovirus (CMV)-specific CD8+/interferon (IFN)- gamma+ cytokine flow cytometry (CFC) assay for patients with CMV retinitis (CMVR), stored peripheral blood mononuclear cell specimens were obtained from patients with active CMVR (i.e., having clinical evidence of absent CMV-protective immunity), as well as from highly active antiretroviral therapy-treated patients with CMVR who were able to discontinue anti-CMV therapy without subsequent progression of retinitis (i.e., having clinical evidence of restored CMV-protective immunity). Positive CD8+/IFN- gamma+ T lymphocyte responses to CMV phosphoprotein 65 or immediate early peptide-pool stimulation were present in specimens from only 3 of 10 patients with active CMVR but were present in at least 1 specimen from all 20 patients with immunorestored CMVR, with a mean of 2.4 specimens/patient tested, spanning up to 6 months of observation (P = .0001). Among the patients with immunorestored CMVR, positive responses were present in all longitudinal specimens from 15 of the 20 patients. These data suggest that further testing of the CMV-specific CD8+/IFN- gamma+ CFC assay, for clinical utility in predicting incident and progressive CMVR disease, is warranted.