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1.
Talanta ; 88: 749-58, 2012 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-22265570

RESUMEN

NIST has performed preliminary research on applying a calibration methodology based on the method of standard additions to the quantification of peptides via reverse-phase liquid chromatography coupled to inductively coupled plasma mass spectrometry (RPLC-ICP-MS). A microwave-assisted lanthanide labeling procedure was developed and applied to derivatize peptides using the macrocyclic bifunctional chemical chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid), which significantly improved the lanthanide labeling yield and reduced reaction times compared to benchtop labeling procedures. Biomolecular MS technologies of matrix-assisted laser desorption ionization (MALDI)-MS and electrospray ionization (ESI)-MS/MS were used in concert with ICP-MS to confirm the results of microwave labeling, sample cleanup and standard additions experiments for several test peptides. The calibration scheme is outlined in detail and contextualized against complementary high accuracy calibration strategies currently employed for ICP-MS detection of biomolecules. Standard additions experiments using native, non-isotopic peptide calibrants confirm the simplicity of the scheme and the potential of applying a blending (recombined sample and spike) procedure, facilitating calibration via co-elution of lanthanide labeled peptides. Ways to improve and fully leverage the analytical methodology are highlighted.


Asunto(s)
Elementos de la Serie de los Lantanoides/química , Péptidos/análisis , Quelantes/química , Cromatografía de Fase Inversa , Compuestos Heterocíclicos con 1 Anillo/química , Marcaje Isotópico , Microondas , Péptidos/química , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Espectrofotometría Atómica , Coloración y Etiquetado
2.
Toxicology ; 262(2): 106-13, 2009 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-19450653

RESUMEN

Epidemiological studies suggest that chronic exposure to inorganic arsenic is associated with cancer of the skin, urinary bladder and lung as well as the kidney and liver. Previous experimental studies have demonstrated increased incidence of liver, lung, ovary, and uterine tumors in mice exposed to 85 ppm (approximately 8 mg/kg) inorganic arsenic during gestation. To further characterize age susceptibility to arsenic carcinogenesis we administered 85 ppm inorganic arsenic in drinking water to C3H mice during gestation, prior to pubescence and post-pubescence to compare proliferative lesion and tumor outcomes over a one-year exposure period. Inorganic arsenic significantly increased the incidence of hyperplasia in urinary bladder (48%) and oviduct (36%) in female mice exposed prior to pubescence (beginning on postnatal day 21 and extending through one year) compared to control mice (19 and 5%, respectively). Arsenic also increased the incidence of hyperplasia in urinary bladder (28%) of female mice continuously exposed to arsenic (beginning on gestation day 8 and extending though one year) compared to gestation only exposed mice (0%). In contrast, inorganic arsenic significantly decreased the incidence of tumors in liver (0%) and adrenal glands (0%) of male mice continuously exposed from gestation through one year, as compared to levels in control (30 and 65%, respectively) and gestation only (33 and 55%, respectively) exposed mice. Together, these results suggest that continuous inorganic arsenic exposure at 85 ppm from gestation through one year increases the incidence and severity of urogenital proliferative lesions in female mice and decreases the incidence of liver and adrenal tumors in male mice. The paradoxical nature of these effects may be related to altered lipid metabolism, the effective dose in each target organ, and/or the shorter one-year observational period.


Asunto(s)
Neoplasias de las Glándulas Suprarrenales/inducido químicamente , Arsenitos/toxicidad , Carcinógenos/toxicidad , Neoplasias Hepáticas/inducido químicamente , Oviductos/efectos de los fármacos , Compuestos de Sodio/toxicidad , Vejiga Urinaria/efectos de los fármacos , Administración Oral , Neoplasias de las Glándulas Suprarrenales/patología , Animales , Esquema de Medicación , Femenino , Hiperplasia/inducido químicamente , Neoplasias Hepáticas/patología , Masculino , Exposición Materna , Intercambio Materno-Fetal , Ratones , Ratones Endogámicos C3H , Oviductos/patología , Embarazo , Efectos Tardíos de la Exposición Prenatal , Factores de Tiempo , Vejiga Urinaria/patología , Abastecimiento de Agua
3.
J Anal At Spectrom ; 23: 342-351, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18677417

RESUMEN

Analyses of arsenic (As) species in tissues and body fluids of individuals chronically exposed to inorganic arsenic (iAs) provide essential information about the exposure level and pattern of iAs metabolism. We have previously described an oxidation state-specific analysis of As species in biological matrices by hydride-generation atomic absorption spectrometry (HG-AAS), using cryotrapping (CT) for preconcentration and separation of arsines. To improve performance and detection limits of the method, HG and CT steps are automated and a conventional flame-in-tube atomizer replaced with a recently developed multiple microflame quartz tube atomizer (multiatomizer). In this system, arsines from As(III)-species are generated in a mixture of Tris-HCl (pH 6) and sodium borohydride. For generation of arsines from both As(III)- and As(V)-species, samples are pretreated with L-cysteine. Under these conditions, dimethylthioarsinic acid, a newly described metabolite of iAs, does not interfere significantly with detection and quantification of methylated trivalent arsenicals. Analytical performance of the automated HG-CT-AAS was characterized by analyses of cultured cells and mouse tissues that contained mono- and dimethylated metabolites of iAs. The capacity to detect methylated As(III)- and As(V)-species was verified, using an in vitro methylation system containing recombinant rat arsenic (+3 oxidation state) methyltransferase and cultured rat hepatocytes treated with iAs. Compared with the previous HG-CT-AAS design, detection limits for iAs and its metabolites have improved significantly with the current system, ranging from 8 to 20 pg. Recoveries of As were between 78 and 117%. The precision of the method was better than 5% for all biological matrices examined. Thus, the automated HG-CT-AAS system provides an effective and sensitive tool for analysis of all major human metabolites of iAs in complex biological matrices.

4.
Spectrochim Acta Part B At Spectrosc ; 63(3): 396-406, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18521190

RESUMEN

An automated system for hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer is described. Arsines are preconcentrated and separated in a Chromosorb filled U-tube. An automated cryotrapping unit, employing nitrogen gas formed upon heating in the detection phase for the displacement of the cooling liquid nitrogen, has been developed. The conditions for separation of arsines in a Chromosorb filled U-tube have been optimized. A complete separation of signals from arsine, methylarsine, dimethylarsine, and trimethylarsine has been achieved within a 60 s reading window. The limits of detection for methylated arsenicals tested were 4 ng l(-1). Selective hydride generation is applied for the oxidation state specific speciation analysis of inorganic and methylated arsenicals. The arsines are generated either exclusively from trivalent or from both tri- and pentavalent inorganic and methylated arsenicals depending on the presence of L-cysteine as a prereductant and/or reaction modifier. A TRIS buffer reaction medium is proposed to overcome narrow optimum concentration range observed for the L-cysteine modified reaction in HCl medium. The system provides uniform peak area sensitivity for all As species. Consequently, the calibration with a single form of As is possible. This method permits a high-throughput speciation analysis of metabolites of inorganic arsenic in relatively complex biological matrices such as cell culture systems without sample pretreatment, thus preserving the distribution of tri- and pentavalent species.

5.
Met Ions Biol Med ; 10: 1-7, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-20467584

RESUMEN

Previous laboratory studies have shown that exposures to inorganic As (iAs) disrupt insulin production or glucose metabolism in cellular and animal models. Epidemiological evidence has also linked chronic human exposures to iAs to an increased risk of diabetes mellitus, a metabolic disease characterized by impaired glucose tolerance and insulin resistance. We have recently shown that arsenite and its methylated metabolites inhibit insulin-stimulated glucose uptake in cultured adipocytes by disrupting insulin-activated signal transduction pathway and preventing insulin-dependent translocation of GLUT4 transporters to the plasma membrane. Here, we present results of follow-up studies using male C57BL/6 mice chronically exposed to arsenite (1 to 50 ppm As) or to its metabolite methylarsonite (0.1 to 5 ppm As) in drinking water for 8 weeks. Results of these studies show that only the exposure to arsenite at the highest level of 50 ppm As produces symptoms attributable to impaired glucose tolerance. Notably, tissue concentrations of iAs and its methylated metabolites in pancreas and in major glucose metabolizing tissues in mice in this exposure group were comparable to the concentrations of total As reported in livers of Bangladeshi residents exposed to much lower concentrations of iAs in drinking water. These results suggest that because mice clear iAs and its metabolites more rapidly than humans, much higher exposure levels may be needed in mouse studies to produce the diabetogenic effects of iAs commonly found in human populations exposed to iAs from environmental sources.

6.
Toxicol Appl Pharmacol ; 227(1): 26-35, 2008 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-18036629

RESUMEN

Dimethylarsinic acid (DMA(V)) is a rat bladder carcinogen and the major urinary metabolite of administered inorganic arsenic in most mammals. This study examined the disposition of pentavalent and trivalent dimethylated arsenic in mice after acute oral administration. Adult female mice were administered [(14)C]-DMA(V) (0.6 or 60 mg As/kg) and sacrificed serially over 24 h. Tissues and excreta were collected for analysis of radioactivity. Other mice were administered unlabeled DMA(V) (0.6 or 60 mg As/kg) or dimethylarsinous acid (DMA(III)) (0.6 mg As/kg) and sacrificed at 2 or 24 h. Tissues (2 h) and urine (24 h) were collected and analyzed for arsenicals. Absorption, distribution and excretion of [(14)C]-DMA(V) were rapid, as radioactivity was detected in tissues and urine at 0.25 h. For low dose DMA(V) mice, there was a greater fractional absorption of DMA(V) and significantly greater tissue concentrations of radioactivity at several time points. Radioactivity distributed greatest to the liver (1-2% of dose) and declined to less than 0.05% in all tissues examined at 24 h. Urinary excretion of radioactivity was significantly greater in the 0.6 mg As/kg DMA(V) group. Conversely, fecal excretion of radioactivity was significantly greater in the high dose group. Urinary metabolites of DMA(V) included DMA(III), trimethylarsine oxide (TMAO), dimethylthioarsinic acid and trimethylarsine sulfide. Urinary metabolites of DMA(III) included TMAO, dimethylthioarsinic acid and trimethylarsine sulfide. DMA(V) was also excreted by DMA(III)-treated mice, showing its sensitivity to oxidation. TMAO was detected in tissues of the high dose DMA(V) group. The low acute toxicity of DMA(V) in the mouse appears to be due in part to its minimal retention and rapid elimination.


Asunto(s)
Arsenicales/farmacocinética , Administración Oral , Animales , Área Bajo la Curva , Arsenicales/administración & dosificación , Relación Dosis-Respuesta a Droga , Femenino , Metilación , Ratones , Espectrofotometría Atómica
7.
Toxicol Appl Pharmacol ; 222(2): 235-42, 2007 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-17559899

RESUMEN

Adult female Fisher 344 rats received drinking water containing 0, 4, 40, 100, or 200 parts per million of dimethylarsinic acid or 100 parts per million of arsenate for 14 days. Urine was collected during the last 24 h of exposure. Tissues were then taken for analysis of dimethylated and trimethylated arsenicals; urines were analyzed for these arsenicals and their thiolated derivatives. In dimethylarsinic acid-treated rats, highest concentrations of dimethylated arsenic were found in blood. In lung, liver, and kidney, concentrations of dimethylated arsenic exceeded those of trimethylated species; in urinary bladder and urine, trimethylated arsenic predominated. Dimethylthioarsinic acid and trimethylarsine sulfide were present in urine of dimethylarsinic acid-treated rats. Concentrations of dimethylated arsenicals were similar in most tissues of dimethylarsinic acid- and arsenate-treated rats, including urinary bladder which is the target for dimethylarsinic acid-induced carcinogenesis in the rat. Mean concentration of dimethylated arsenic was significantly higher (P<0.05) in urine of dimethylarsinic acid-treated rats than in arsenate-treated rats, suggesting a difference between treatment groups in the flux of dimethylated arsenic through urinary bladder. Concentrations of trimethylated arsenic concentrations were consistently higher in dimethylarsinic acid-treated rats than in arsenate-treated rats; these differences were significant (P<0.05) in liver, urinary bladder, and urine. Concentrations of dimethylthioarsinic acid and trimethylarsine sulfide were higher in urine from dimethylarsinic acid-treated rats than from arsenate-treated rats. Dimethylarsinic acid is extensively metabolized in the rat, yielding significant concentrations of trimethylated species and of thiolated derivatives. One or more of these metabolites could be the species causing alterations of cellular function that lead to tumors in the urinary bladder.


Asunto(s)
Arseniatos/farmacocinética , Ácido Cacodílico/farmacocinética , Animales , Arseniatos/metabolismo , Arseniatos/orina , Arsenicales/sangre , Arsenicales/orina , Arsenitos/sangre , Arsenitos/química , Arsenitos/orina , Ácido Cacodílico/metabolismo , Ácido Cacodílico/orina , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Femenino , Herbicidas/metabolismo , Herbicidas/farmacocinética , Herbicidas/orina , Riñón/metabolismo , Hígado/metabolismo , Pulmón/metabolismo , Estructura Molecular , Ratas , Ratas Endogámicas F344 , Espectrometría de Masa por Ionización de Electrospray , Distribución Tisular , Vejiga Urinaria/metabolismo
8.
Toxicol Appl Pharmacol ; 222(3): 305-14, 2007 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-17336358

RESUMEN

Previous epidemiologic studies found increased prevalences of type 2 diabetes mellitus in populations exposed to high levels of inorganic arsenic (iAs) in drinking water. Although results of epidemiologic studies in low-exposure areas or occupational settings have been inconclusive, laboratory research has shown that exposures to iAs can produce effects that are consistent with type 2 diabetes. The current paper reviews the results of laboratory studies that examined the effects of iAs on glucose metabolism and describes new experiments in which the diabetogenic effects of iAs exposure were reproduced in a mouse model. Here, weanling male C57BL/6 mice drank deionized water with or without the addition of arsenite (25 or 50 ppm As) for 8 weeks. Intraperitoneal glucose tolerance tests revealed impaired glucose tolerance in mice exposed to 50 ppm As, but not to 25 ppm As. Exposure to 25 and 50 ppm As in drinking-water resulted in proportional increases in the concentration of iAs and its metabolites in the liver and in organs targeted by type 2 diabetes, including pancreas, skeletal muscle and adipose tissue. Dimethylarsenic was the predominant form of As in the tissues of mice in both 25 and 50 ppm groups. Notably, the average concentration of total speciated arsenic in livers from mice in the 50 ppm group was comparable to the highest concentration of total arsenic reported in the livers of Bangladeshi residents who had consumed water with an order of magnitude lower level of iAs. These data suggest that mice are less susceptible than humans to the diabetogenic effects of chronic exposure to iAs due to a more efficient clearance of iAs or its metabolites from target tissues.


Asunto(s)
Arsénico/farmacología , Arsénico/toxicidad , Diabetes Mellitus/inducido químicamente , Glucosa/metabolismo , Homeostasis/efectos de los fármacos , Animales , Arsénico/farmacocinética , Glucemia/metabolismo , Peso Corporal/efectos de los fármacos , Células Cultivadas , Diabetes Mellitus/metabolismo , Ingestión de Líquidos/efectos de los fármacos , Prueba de Tolerancia a la Glucosa , Masculino , Ratones , Ratones Endogámicos C57BL , Distribución Tisular
9.
Exp Biol Med (Maywood) ; 232(1): 3-13, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17202581

RESUMEN

Metabolic conversion of inorganic arsenic into methylated products is a multistep process that yields mono-, di-, and trimethylated arsenicals. In recent years, it has become apparent that formation of methylated metabolites of inorganic arsenic is not necessarily a detoxification process. Intermediates and products formed in this pathway may be more reactive and toxic than inorganic arsenic. Like all metabolic pathways, understanding the pathway for arsenic methylation involves identification of each individual step in the process and the characterization of the molecules which participate in each step. Among several arsenic methyltransferases that have been identified, arsenic (+3 oxidation state) methyltransferase is the one best characterized at the genetic and functional levels. This review focuses on phylogenetic relationships in the deuterostomal lineage for this enzyme and on the relation between genotype for arsenic (+3 oxidation state) methyltransferase and phenotype for conversion of inorganic arsenic to methylated metabolites. Two conceptual models for function of arsenic (+3 oxidation state) methyltransferase which posit different roles for cellular reductants in the conversion of inorganic arsenic to methylated metabolites are compared. Although each model accurately represents some aspects of enzyme's role in the pathway for arsenic methylation, neither model is a fully satisfactory representation of all the steps in this metabolic pathway. Additional information on the structure and function of the enzyme will be needed to develop a more comprehensive model for this pathway.


Asunto(s)
Arsenicales/metabolismo , Metiltransferasas/genética , Metiltransferasas/metabolismo , Secuencia de Aminoácidos , Animales , Glutatión/metabolismo , Humanos , Metilación , Metiltransferasas/química , Datos de Secuencia Molecular , Oxidación-Reducción
10.
Science ; 315(5810): 387-9, 2007 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-17234949

RESUMEN

Cysteine (Cys) residues often play critical roles in proteins; however, identification of their specific functions has been limited to case-by-case experimental approaches. We developed a procedure for high-throughput identification of catalytic redox-active Cys in proteins by searching for sporadic selenocysteine-Cys pairs in sequence databases. This method is independent of protein family, structure, and taxon. We used it to selectively detect the majority of known proteins with redox-active Cys and to make additional predictions, one of which was verified. Rapid accumulation of sequence information from genomic and metagenomic projects should allow detection of many additional oxidoreductase families as well as identification of redox-active Cys in these proteins.


Asunto(s)
Cisteína/química , Bases de Datos de Ácidos Nucleicos , Bases de Datos de Proteínas , Enzimas/química , Proteínas/química , Selenoproteínas/química , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Animales , Proteínas Arqueales/química , Proteínas Bacterianas/química , Secuencia de Bases , Catálisis , Biología Computacional , Cisteína/análisis , Células Eucariotas , Evolución Molecular , Metiltransferasas/química , Datos de Secuencia Molecular , Oxidación-Reducción , Oxidorreductasas/química , Selenocisteína/química
11.
Toxicology ; 224(1-2): 147-55, 2006 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-16753250

RESUMEN

Exposure of pregnant C3H/HeNCR mice to 42.5- or 85-ppm of arsenic as sodium arsenite in drinking water between days 8 and 18 of gestation markedly increases tumor incidence in their offspring. In the work reported here, distribution of inorganic arsenic and its metabolites, methyl arsenic and dimethyl arsenic, were determined in maternal and fetal tissues collected on gestational day 18 of these exposure regimens. Tissues were collected from three females and from associated fetuses exposed to each dosage level. Concentrations of total speciated arsenic (sum of inorganic, methyl, and dimethyl arsenic) were higher in maternal tissues than in placenta and fetal tissues; total speciated arsenic concentration in placenta exceeded those in fetal tissues. Significant dosage-dependent (42.5 ppm versus 85 ppm of arsenite in drinking water) differences were found in total speciated arsenic concentrations in maternal lung (p<0.01) and liver (p<0.001). Total speciated arsenic concentrations did not differ significantly between dosage levels for maternal blood or for fetal lung, liver, and blood, or for placenta. Percentages of inorganic, methyl, or dimethyl arsenic in maternal or fetal tissues were not dosage-dependent. Over the range of total speciated arsenic concentrations in most maternal and fetal tissues, dimethyl arsenic was the most abundant arsenical. However, in maternal liver at the highest total speciated arsenic concentration, inorganic arsenic was the most abundant arsenical, suggesting that a high tissue burden of arsenic affected formation or retention of methylated species in this organ. Tissue concentration-dependent processes could affect kinetics of transfer of inorganic arsenic or its metabolites from mother to fetus.


Asunto(s)
Arsenicales/farmacocinética , Arsenitos/farmacocinética , Feto/metabolismo , Preñez/metabolismo , Animales , Femenino , Desarrollo Fetal , Intercambio Materno-Fetal , Ratones , Ratones Endogámicos C3H , Placenta/metabolismo , Embarazo , Distribución Tisular
12.
Environ Toxicol Chem ; 25(2): 458-69, 2006 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-16519307

RESUMEN

We live-trapped 40 northern pocket gophers across two years from the Anaconda Smelter Superfund Site, Anaconda, Montana, USA, to determine their exposure to five metal contaminants and effects of exposure on selected measurements. Soil, gopher blood, liver, kidney, and carcass samples were analyzed for arsenic, cadmium, lead, copper, and zinc. Hematological parameters, kidney and liver porphyrins, and red blood cell delta-aminolevulinic acid dehydratase (ALAD) activity were also measured. Micronutrients Cu and Zn were detected in all tissues analyzed, and Cd, Pb, and As were detected less frequently. We report differences in metal distribution among different tissues and differences in bioaccumulation for different metals within the same tissue. No significant differences were observed in concentrations of Zn or Cu in any tissue across the study site, but relationships between lead in soil and lead in carcass proved especially strong (r2 = 0.80; p < 0.001; n = 18). Among biomarker data, we observed a negative relationship between concentration of lead in the soil and ALAD activity in gophers with detectable concentrations of lead in their blood (r2 = 0.45; p = 0.006; n = 15). Results of this study suggest that northern pocket gophers are useful biomonitors of environmental Pb, Cd, and As contamination, and their broad geographic range across North America could allow them to be an important component of site-specific metals assessments.


Asunto(s)
Arsénico/farmacocinética , Ardillas Terrestres , Residuos Peligrosos , Metales Pesados/farmacocinética , Contaminantes del Suelo/farmacocinética , Animales , Arsénico/análisis , Biomarcadores/análisis , Recuento de Células Sanguíneas/veterinaria , Monitoreo del Ambiente/métodos , Metales Pesados/análisis , Dinámica Poblacional , Porfobilinógeno Sintasa/sangre , Contaminantes del Suelo/análisis , Distribución Tisular
13.
Environ Res ; 101(2): 213-20, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16188251

RESUMEN

Accurate quantitation of any contaminant of interest is critical for exposure assessment and metabolism studies that support risk assessment. A preliminary step in an arsenic exposure assessment study in Nevada quantified total arsenic (TAs) concentrations in tissues as biomarkers of exposure. Participants in this study (n=95) were at least 45 years old, had lived in the area for more than 20 years, and were exposed to a wide range of arsenic concentrations in drinking water (3-2,100 ppb). Concentrations of TAs in blood, urine, and toenails determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) ranged from below detection to 0.03, 0.76, and 12 ppm, respectively; TAs in blood rarely exceeded the limit of detection. For comparison, TAs in toenails determined by neutron activation analysis (NAA) ranged from below detection to 16 ppm. Significant (P<0.0001) positive regressions were seen between the TAs concentration in toenails and in drinking water (adjusted r(2)=0.3557 HG-AFS, adjusted r(2)=0.3922 NAA); TAs concentrations in urine were not described by drinking water As (adjusted r(2)=0.0170, P=0.1369). Analyses of TAs in toenails by HGAFS and NAA yielded highly concordant estimates (r=0.7977, P<0.0001). These results suggest that toenails are a better biomarker of chronic As exposure than urine in the current study, because the sequestration of As in toenails provides an integration of exposure over time that does not occur in urine.


Asunto(s)
Arsénico/análisis , Biomarcadores/análisis , Uñas/química , Contaminantes Químicos del Agua/análisis , Arsénico/sangre , Arsénico/orina , Humanos , Espectrometría de Masas , Espectrofotometría Atómica , Contaminantes Químicos del Agua/sangre , Contaminantes Químicos del Agua/orina
14.
Toxicol Appl Pharmacol ; 208(2): 186-97, 2005 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-16183392

RESUMEN

Exposure to monomethylarsonic acid (MMA(V)) and monomethylarsonous acid (MMA(III)) can result from their formation as metabolites of inorganic arsenic and by the use of the sodium salts of MMA(V) as herbicides. This study compared the disposition of MMA(V) and MMA(III) in adult female B6C3F1 mice. Mice were gavaged p.o. with MMA(V), either unlabeled or labeled with 14C at two dose levels (0.4 or 40 mg As/kg). Other mice were dosed p.o. with unlabeled MMA(III) at one dose level (0.4 mg As/kg). Mice were housed in metabolism cages for collection of excreta and sacrificed serially over 24 h for collection of tissues. MMA(V)-derived radioactivity was rapidly absorbed, distributed and excreted. By 8 h post-exposure, 80% of both doses of MMA(V) were eliminated in urine and feces. Absorption of MMA(V) was dose dependent; that is, there was less than a 100-fold difference between the two dose levels in the area under the curves for the concentration-time profiles of arsenic in blood and major organs. In addition, urinary excretion of MMA(V)-derived radioactivity in the low dose group was significantly greater (P < 0.05) than in the high dose group. Conversely, fecal excretion of MMA(V)-derived radioactivity was significantly greater (P < 0.05) in the high dose group than in the low dose group. Speciation of arsenic by hydride generation-atomic absorption spectrometry in urine and tissues of mice administered MMA(V) or MMA(III) found that methylation of MMA(V) was limited while the methylation of MMA(III) was extensive. Less than 10% of the dose excreted in urine of MMA(V)-treated mice was in the form of methylated products, whereas it was greater than 90% for MMA(III)-treated mice. In MMA(V)-treated mice, 25% or less of the tissue arsenic was in the form of dimethylarsenic, whereas in MMA(III)-treated mice, 75% or more of the tissue arsenic was in the form of dimethylarsenic. Based on urinary analysis, administered dose of MMA(V) did not affect the level of its metabolites excreted. In the tested range, dose affects the absorption, distribution and route of excretion of MMA(V) but not its metabolism.


Asunto(s)
Arsenicales/farmacocinética , Administración Oral , Animales , Área Bajo la Curva , Arsenicales/química , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Femenino , Semivida , Absorción Intestinal , Ratones , Ratones Endogámicos , Compuestos Organometálicos/farmacocinética , Espectrofotometría Atómica , Distribución Tisular
15.
Arch Environ Contam Toxicol ; 44(2): 265-71, 2003 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-12520399

RESUMEN

Mercury occurrence in prothonotary warblers (Protonotaria citrea) was evaluated over two years in southern Alabama. Mercury was found in warbler nestlings and adults inhabiting National Priority List (NPL) sites in McIntosh, Alabama. Food items that were collected from nestlings also contained elevated mercury. When mercury concentrations in soil, food, and nestling were plotted at each nest box location, the distribution of mercury in the three matrices yielded information that direct bioaccumulation factors could not. There were site differences in mercury accumulation in nestlings inhabiting the NPL sites. Nestling mercury accumulation correlated with solid mercury concentrations near the nest box where the nestling was raised. Trophic transport of mercury was poorly defined by mercury in food; however, closer examination of prey items shows that food source influences accumulation. Mercury distributions in matrices provide useful information of uptake that can be integrated with risk assessment endpoints.


Asunto(s)
Cadena Alimentaria , Mercurio/farmacocinética , Pájaros Cantores , Alabama , Animales , Animales Recién Nacidos , Riñón/química , Mercurio/análisis , Plantas , Plantas Comestibles , Contaminantes del Suelo/análisis , Distribución Tisular
16.
Environ Pollut ; 119(2): 261-8, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12152833

RESUMEN

A study was conducted to assess differences in contaminant assimilation among co-occurring white-footed mice (Peromyscus leucopus) and rice rats (Oryomys palustris) captured at a contaminated site. Rodents were collected from five areas at the Paducah Gaseous Diffusion Plant (PGDP), a uranium enrichment facility. Relatively few white-footed mice (8.7%) had quantifiable concentrations of PCBs compared to 42% of rice rats (chi2 = 6.49, d.f. = 1, P < 0.025), and seven of the 11 rice rats (64%) over 50 g body mass had quantifiable concentrations of PCBs in their livers. White-footed mice had higher mean concentrations of barium (P < 0.0001), chromium (P = 0.0010), copper (P = 0.0011), lead (P = 0.0335), and aluminum (P = 0.0006) than rice rats at all five sampling areas. Species-specific differences in accumulation of PCBs and metals were observed and attributed to differences in habitat use and foraging strategies.


Asunto(s)
Monitoreo del Ambiente/métodos , Contaminantes Ambientales/farmacocinética , Peromyscus/metabolismo , Bifenilos Policlorados/farmacocinética , Sigmodontinae/metabolismo , Animales , Contaminantes Ambientales/análisis , Femenino , Hígado/química , Masculino , Metales/análisis , Metales/farmacocinética , Bifenilos Policlorados/análisis , Ratas , Especificidad de la Especie
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