Ng L (ng + l)

Distribution by Scientific Domains


Selected Abstracts


Xenoestrogenic effects of ethinylestradiol in zebrafish (Danio rerio)

ENVIRONMENTAL TOXICOLOGY, Issue 3 2004
Bram J. Versonnen
Abstract To assess the estrogenic effects of ethinylestradiol on zebrafish, zebrafish at different developmental stages (embryos, juveniles, and adults) were exposed to the synthetic hormone ethinylestradiol (EE2) in concentrations of 1, 10, and 100 ng/L for up to 33 days. Survival, hatching, length, weight, growth, condition, hepatosomatic index, gonadosomatic index, and vitellogenin (VTG) production were examined. Exposure of zebrafish juveniles and embryos to 100 ng EE2/L for up to 33 days had significant effects on survival, growth, and hatching. Two VTG fragments with molecular weights of approximately 140 and 170 kDa were detected with protein electrophoresis and Western blotting in the blood of exposed males and exposed and unexposed females, as well as in whole-body homogenates of exposed and unexposed juveniles. Significantly higher VTG concentrations (compared to controls) were measured in adults exposed to 10 and 100 ng EE2/L for 14 days, but not in fish exposed to 1 ng EE2/L. This study demonstrated that (1) zebrafish juveniles, larvae, and embryos are sensitive to the toxic effects of the endocrine disrupter EE2; (2) the effects on VTG production in adults are detected after exposure to environmentally relevant concentrations of EE2; (3) unexposed juvenile zebrafish produce measurable concentrations of VTG. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 198,206, 2004. [source]


Estrogenic endpoints in fish early life-stage tests: Luciferase and vitellogenin induction in estrogen-responsive transgenic zebrafish

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006
Rinus Bogers
Abstract This study incorporated specific endpoints for estrogenic activity in the early life-stage (ELS) test, as described in Guideline 210 of the Organization for Economic Cooperation and Development and traditionally used for toxicity screening of chemicals. A transgenic zebrafish model expressing an estrogen receptor,mediated luciferase reporter gene was exposed to ethi-nylestradiol (EE2), and luciferase activity as well as vitellogenin (VTG) was measured. Concentrations of EE2 were tested at 1, 3, or 10 ng/L for 30 d from fertilization or during only the last 4 d with dimethylsulfoxide (DMSO) as presolvent (0.01%). Exposure to EE2 induced no toxic effects. Mean body weights were significantly higher in groups exposed for 30 d in the presence of DMSO, but condition factors were not affected. Significant luciferase and VTG induction occurred following 30-d exposure (3 and 10 ng EE2/L), while only VTG levels were affected in the 4-d exposure (10 ng EE2/L). This study demonstrated the usefulness of incorporating estrogenic endpoints in the OECD ELS test, fitting the requirements for screening estrogenic activity of chemicals. Quantitative measurement of both VTG and luciferase activity proved to be rapid and sensitive. Additional value of using transgenic zebrafish lies in combining VTG measurement with the more mechanistic approach of luciferase induction in one experiment. [source]


In vitro and in vivo estrogenicity and toxicity of o -, m -, and p -dichlorobenzene

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2003
Bram J. Versonnen
Abstract The estrogenicity of o -, m -, and p -dichlorobenzene (DCB) was evaluated with a yeast estrogen screen (YES) and zebrafish (Danio rerio) vitellogenin (VTG) assays. With the YES, p -DCB and m -DCB were found to be estrogenic in a concentration-responsive manner. The relative potency measured with the YES (relative to 17,-estradiol) was 2.2 × 10,7 for p -DCB and 1.04 × 10,8 for m -DCB. Following acute toxicity tests with the zebrafish, plasma VTG production was measured to examine the in vivo estrogenic activity of the three compounds after a 14-d exposure. Adult zebrafish were exposed to different concentrations of o -, m - and p -DCB, ranging from 0.1 to 32 mg/L; ethynylestradiol ([EE2]; 5 ng/L, 10 ng/L, 50 ng/L, and 100 ng/L) was used as a positive control. After exposure, blood samples were taken and protein electrophoresis was performed to determine the relative VTG content. Gonadosomatic indices (GSI) and condition factors (CF) were also calculated. Elevated VTG levels and decreased female GSIs were found in fish exposed to ,5 ng EE2/L and in fish exposed to ,10 mg p -DCB/L. Low GSIs coincided with high levels of VTG in the blood of female zebrafish. This relation was not only found in fish exposed to EE2 but also in controls and fish exposed to DCB. Therefore, a direct or indirect effect of VTG on the GSI is suggested rather than a direct toxic effect of the tested compounds on the gonads. [source]


Effects of immersion water temperature on whole-body fluid distribution in humans

ACTA PHYSIOLOGICA, Issue 1 2004
J. M. Stocks
Abstract Aim:, In this study, we quantified acute changes in the intracellular and extracellular fluid compartments during upright neutral- and cold-water immersion. We hypothesized that, during short-term cold immersion, fluid shifts would be wholly restricted to the extracellular space. Methods:, Seven males were immersed 30 days apart: control (33.3 ° SD 0.6 °C); and cold (18.1 ° SD 0.3 °C). Posture was controlled for 4 h prior to a 60-min seated immersion. Results:, Significant reductions in terminal oesophageal (36.9 ° ± 0.1 °,36.3 ° ± 0.1 °C) and mean skin temperatures (30.3 ° ± 0.3 °,23.0 ° ± 0.3 °C) were observed during the cold, but not the control immersion. Both immersions elicited a reduction in intracellular fluid [20.17 ± 6.02 mL kg,1 (control) vs. 22.72 ± 9.90 mL kg,1], while total body water (TBW) remained stable. However, significant plasma volume (PV) divergence was apparent between the trials at 60 min [12.5 ± 1.0% (control) vs. 6.1 ± 3.1%; P < 0.05], along with a significant haemodilution in the control state (P < 0.05). Plasma atrial natriuretic peptide concentration increased from 18.0 ± 1.6 to 58.7 ± 15.1 ng L,1 (P < 0.05) during cold immersion, consistent with its role in PV regulation. We observed that, regardless of the direction of the PV change, both upright immersions elicited reductions in intracellular fluid. Conclusion:, These observations have two implications. First, one cannot assume that PV changes reflect those of the entire extracellular compartment. Second, since immersion also increases interstitial fluid pressure, fluid leaving the interstitium must have been rapidly replaced by intracellular water. [source]


Novel Sensitive Voltammetric Detection of Trace Gallium(III) with Presence of Catechol Using Mercury Film Silver Based Electrode

ELECTROANALYSIS, Issue 16 2009
Robert Piech
Abstract A new adsorptive stripping voltammetric method for the determination of trace gallium(III) based on the adsorption of gallium(III)-catechol complex on the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2,nM (0.14,,g L,1) to 100,nM (6.97,,g L,1) for a preconcentration time of 30,s, with correlation coefficient of 0.9993. For a Hg(Ag)FE with a surface area of 9.7,mm2 the detection limit for a preconcentration time of 90,s is as low as 7,ng L,1. The repeatability of the method at a concentration level of the analyte as low as 0.05,,g L,1, expressed as RSD is 3.6% (n=5). The proposed method was successfully applied by studying the natural samples and simultaneous recovery of Ga(III) from spiked water and sediment samples. [source]


Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

ELECTROANALYSIS, Issue 7 2008
Robert Piech
Abstract New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12,mm2, both electrodes are characterized by very good surface reproducibility (,2%) and long-term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1,2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16,ng L,1 to 4.8,,g L,1 for Hg(Cu)FE, and up to 6.4,,g L,1 for Hg(Ag)FE (tacc=15,s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and tacc=60,s are as low as 14,ng L,1 for Hg(Cu)FE and 4,ng L,1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water. [source]


Trace Determination of Chromium by Square-Wave Adsorptive Stripping Voltammetry on Bismuth Film Electrodes

ELECTROANALYSIS, Issue 21 2004
Eleni Chatzitheodorou
Abstract This works reports the use of adsorptive stripping voltammetry (AdSV) for the trace determination of chromium on a rotating-disk bismuth-film electrode (BFE). During the reductive accumulation step, all the chromium species in the sample were reduced to Cr(III) which was complexed with cupferron and the complex was accumulated by adsorption on the surface of a preplated BFE. The stripping step was carried out by using a square-wave (SW) potential-time voltammetric signal. Electrochemical cleaning of the bismuth film was employed, enabling the same bismuth film to be used for a series of measurements in the presence of dissolved oxygen. The experimental variables as well as potential interferences were investigated and the figures of merit of the method were established. Using the selected conditions, the 3, limit of detection for chromium was 100,ng L,1 (for 120,s of preconcentration) and the relative standard deviation was 3.6% at the 2,,g L,1 level (n=8). Finally, the method was applied to the determination of chromium in real samples with satisfactory results. [source]


A new morphospecies of Microcystis sp. forming bloom in the Cheffia dam (Algeria): Seasonal variation of microcystin concentrations in raw water and their removal in a full-scale treatment plant

ENVIRONMENTAL TOXICOLOGY, Issue 4 2007
Hichèm Nasri
Abstract Toxic cyanobacterial blooms are an increasing problem in Algeria. The production of cyanotoxins (microcystins) and their presence in drinking water represent growing hazards to human health. In this study, seasonal variations in the concentrations of total microcystins and physicochemical parameters (pH, temperature, dissolved oxygen, nitrate, orthophosphate, and chlorophyll- a) were analyzed in the Cheffia dam (Algeria), mainly used to supply drinking water. The removal of cyanobacterial cells and microcystins was also evaluated in full-scale plant associated with the Cheffia reservoir. The levels of microcystins (MCYSTs) in both raw and drinking water were evaluated using the protein phosphatase type 2A (PP2A) inhibition test as MCYST-LR equivalents. Identification of microcystin variants was achieved by LC/MS/MS. During the period of study (March,December 2004), microscopic observation showed the dominance in the autumn months (September,November) of a new morphospecies of Microcystis sp. The MCYST-LR equivalent concentrations in raw water varied between 50.8 and 28,886 ng L,1. The highest level of toxins was observed in October 2004 and was significantly correlated with the chlorophyll- a. Three variants of microcystins assigned as microcystin-YR (MCYST-YR), microcystin-LR (MCYST-LR), and 6Z -Adda stereoisomer of MCYST-LR were observed in the crude extract of the Microcystis sp. bloom sample. During the bloom period, total elimination of Microcystis sp. and toxins were achieved through a classical treatment plant comprised of coagulation and flocculation, powdered activated carbon at 15 mg L,1, slow sand filtration and chlorination before storage. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 347,356, 2007. [source]


Environmental risk assessment of human pharmaceuticals in the European Union: A case study with the ,-blocker atenolol

INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue S1 2010
Anette Küster
Abstract ,-Adrenergic receptor blockers (,-blockers) are applied to treat high blood pressure, ischemic heart disease, and heart rhythm disturbances. Due to their widespread use and limited human metabolism, ,-blockers are widely detected in sewage effluents and surface waters. ,-Adrenergic receptors have been characterized in fish and other aquatic animals, so it can be expected that physiological processes regulated by these receptors in wild animals may be affected by the presence of ,-blockers. Because ecotoxicological data on ,-blockers are scarce, it was decided to choose the ,-blocker atenolol as a case study pharmaceutical within the project ERAPharm. A starting point for the assessment of potential environmental risks was the European guideline on the environmental risk assessment of medicinal products for human use. In Phase I of the risk assessment, the initial predicted environmental concentration (PEC) of atenolol in surface water (500,ng L,1) exceeded the action limit of 10,ng L,1. Thus, a Phase II risk assessment was conducted showing acceptable risks for surface water, for groundwater, and for aquatic microorganisms. Furthermore, atenolol showed a low potential for bioaccumulation as indicated by its low lipophilicity (log KOW,=,0.16), a low potential for exposure of the terrestrial compartment via sludge (log KOC,=,2.17), and a low affinity for sorption to the sediment. Thus, the risk assessment according to Phase II-Tier A did not reveal any unacceptable risk for atenolol. Beyond the requirements of the guideline, additional data on effects and fate were generated within ERAPharm. A 2-generation reproduction test with the waterflea Daphnia magna resulted in the most sensitive no-observed-effect concentration (NOEC) of 1.8,mg L,1. However, even with this NOEC, a risk quotient of 0.003 was calculated, which is still well below the risk threshold limit of 1. Additional studies confirm the outcome of the environmental risk assessment according to EMEA/CHMP (2006). However, atenolol should not be considered as representative for other ,-blockers, such as metoprolol, oxprenolol, and propranolol, some of which show significantly different physicochemical characteristics and varying toxicological profiles in mammalian studies. Integr Environ Assess Manag 2010;6:514,523. © 2009 SETAC [source]


Validation of a quantitative assay using GC/MS for trace determination of free and conjugated estrogens in environmental water samples

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 1-2 2003
Asmaa Mouatassim-Souali
Abstract It has been shown that sewage effluent can discharge human hormones and pharmaceuticals, particularly estrogens and synthetic chemicals, which are able to disrupt animal and human endocrine systems into surface waters. Since many surface waters receive sewage effluent and are subsequently used to produce drinking water, it is of principal interest to assess their contamination level and thereby their possible public health and environmental impact. To date, no data concerning the occurrence of estrogens present in the French aquatic environment are available. We therefore developed and validated an analytical procedure, which allows simultaneous quantitative determination of three natural estrogens, 17,-estradiol, estriol, and estrone and one of the synthetic estrogens most widely used in contraception, ethinylestradiol, in water. Water samples are extracted using solid-phase extraction (SPE) and then separated by gas-chromatography coupled with mass spectrometric detection. Under our conditions, detection limits of estrogens reached the pg range of injected sample, i. e. less than 0.1 ng L,1. Conjugated estrogens were also investigated using the same procedure as described above but with a enzymatic hydrolysis preliminary step before extraction. The analysis of samples collected from four wastewater treatment plants and from surface water showed significant concentrations of estrogens ranging from 2 to 18 ng L,1 and from 0.5 to 3 ng L,1, respectively. Furthermore, no estrogen conjugated forms were detected in the water samples. [source]


Comparison of inductively coupled plasma mass spectrometry techniques in the determination of platinum in urine: quadrupole vs. sector field

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2005
Sandro Spezia
In recent years the increasing use of platinum (Pt) both in medical and in industrial applications has caused its growing anthropogenic emission and spread in the environment. Pt is released into the atmosphere by exhaust catalytic converters, and Pt compounds are often used in antitumour therapies. As a consequence, significant amounts of Pt can be detected in hospital wastewaters. This can lead to an increase in the exposure levels to Pt, especially in urban areas. It is therefore necessary to determine Pt reference values in the general population, by using suitable procedures able to achieve adequate analytical performances. Several measurements of Pt in biological fluids have been reported, but the analytical methods used for the determination of Pt often lack information about the uncertainty of the results, especially for low concentrations of urinary Pt in non-occupationally exposed subjects. The present paper considers the measurement of urinary Pt levels in a general population group from central Italy, by both quadrupole (Q) and sector field (SF) inductively coupled plasma mass spectrometry (ICP-MS). The two procedures were validated and their expanded uncertainties were evaluated. The limits of detection (LODs), calculated taking into account dilution factors, were 0.18 and 0.05,ng L,1 of Pt for the Q and SF procedures, respectively. The median value observed was 4.13,ng L,1 of Pt in urine, while the relative combined uncertainty at 5,ng L,1 was below 20% with both ICP-MS techniques. These data are in good agreement with those reported in the literature for similar studies. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Evaluation of ecotoxicity and fate of methylated butyltins in sediments and seawater from Tokyo Bay, Japan

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2007
Ryo Kurihara
Abstract We analyzed the fate of organotins in seawater and sediments from Tokyo Bay, Japan, by gas chromatography/inductively coupled plasma mass spectrometry. We also measured the toxicity of methylated butyltins by in vitro bioassays, the retinoid × receptor (RXR) activation method, and the marine luminescent bacterium Vibrio fischeri. Concentrations of tributyltin (TBT) and tributylmonomethyltin (TBMMT) in seawater were 0.0636 to 0.419 and 0.0050 to 0.108 ng Sn/L and in sediment were 7.51 to 17.8 and 3.67 to 6.87 ng Sn/wet weight g, respectively. Methylated butyltins did not activate RXR and were not toxic to bacteria. Tributylmonomethyltin in seawater would elute from sediment since TBMMT-to-TBT ratios showed a positive correlation (r2 = 0.858) between sediment and deep seawater. Both methylation and debutylation of TBT seem to be major routes of decomposition of TBT in sediment. Methylation of TBT would not only cause subsequent volatilization but also decrease the toxicity of TBT species in the marine environment. [source]


Accumulation of tributyltin in Hyalella azteca as an indicator of chronic toxicity: Survival, growth, and reproduction

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2004
Adrienne J. Bartlett
Abstract The chronic toxicity of tributyltin (TBT) was examined by exposing two successive generations of the freshwater amphipod, Hyalella azteca, to sediments spiked with TBT. Survival was the most sensitive measure of effect, with lethal concentration resulting in 50% mortality (LC50) values on a water and body concentration basis ranging from 76 to 145 ng Sn/L and 2,790 to 4,300 ng Sn/g, respectively. Individual growth of amphipods was not negatively affected by TBT, and although reproduction might be more sensitive than survival, the data were too variable to use on a routine basis. There were no detectable TBT-induced differences in the response between first- and second-generation animals. The relationship between toxicity and bioaccumulation of TBT in H. azteca was determined and can be used as a tool to predict the toxicity of TBT in environmental samples. Body concentrations exceeding 2,000 ng Sn/g in H. azteca exposed to field-collected samples would indicate that chronic toxicity due to TBT is likely occurring in amphipod populations at those sites. [source]


Simultaneous Determination of Fluorine, Chlorine, Bromine and Iodine in Six Geochemical Reference Materials Using Pyrohydrolysis, Ion Chromatography and Inductively Coupled Plasma-Mass Spectrometry

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 4 2009
Hélène Balcone-Boissard
halogènes; pyrohydrolyse; chromatographie ionique; spectrométrie de masse couplée à une source de plasma induit; matériaux géologiques de référence Concentrations of halogens (fluorine, chlorine, bromine and iodine) were determined in six geochemical reference materials (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2). Halogens were first extracted from powdered samples using a pyrohydrolysis technique, then hydrolysis solutions were analysed by ion chromatography for F and Cl and inductively coupled plasma-mass spectrometry for Br and I. The detection limits in solutions were 100 ,g l,1 for both F and Cl and 10 ng l,1 for Br and I. Considering the extraction procedure, performed on a maximum of 500 mg of sample and producing 100 ml of pyrohydrolysis solution, detection limits in rock samples were 20 mg kg,1 for F and Cl and 2 ,g kg,1 for Br and I. The mean analytical errors on the studied composition ranges were estimated at 10 mg kg,1 for F and Cl, 100 ,g kg,1 for Br and 25 ,g kg,1 for I. The concentration values, based on repeated (generally > 10) sample analysis, were in good agreement generally with published values and narrowed the mean dispersion around mean values. Large dispersions are discussed in terms of samples heterogeneity and contaminations during sample preparation. Basaltic RMs were found to be more suitable for studies of halogen compositions than differentiated rock material, especially granites , the powders of which were heterogeneous in halogens at the 500 mg level. Les concentrations en halogènes (fluor, chlore, brome et iode) on été déterminées dans 6 matériaux géologiques de référence (BHVO-2, GS-N, JG-1, JR-1, JB-1b, JB-2), distribués par le GSJ, l'USGS et le CRPG. Les halogènes étaient d'abord extraits des échantillons, disponibles sous forme de poudre, par pyrohydrolyse. F et Cl sont ensuite analysés par chromatographie ionique, Br et I par spectrométrie de masse couplée à une source de plasma induit. Les limites de détection sont de 100 ,g l,1 pour F et Cl, et de 10 ng l,1 pour Br et I, respectivement. L'extraction des halogènes était réalisée sur 500 mg de poudre de roche, produisant 100 ml de solution d'extraction. Ainsi, pour les échantillons de roche, les limites de détection étaient de 20 mg kg,1 pour F et Cl, et 2 ,g kg,1 pour Br et I. L'erreur analytique moyenne sur la gamme de concentration étudiée est estimée à 10 mg kg,1 pour F et Cl, 100 ,g kg,1 pour Br et 25 ,g kg,1 pour I. Les valeurs de concentrations données, obtenues par l'analyse répétée (> 10) du même échantillon étaient en accord avec les valeurs reportées dans la littérature. Elles présentent en général une plus faible dispersion autour de la valeur moyenne. Dans le cas d'une importante dispersion des résultats, celle-ci est discutée en terme d'hétérogénéité de l'échantillon analysé et de contamination durant la préparation du matériel de référence. Les échantillons de référence de composition basaltique se révèlent être plus appropriés pour étudier les compositions en halogènes que les matériaux correspondant à des roches différenciées, en particulier des granites dont la distribution en halogènes apparaît hétérogène dans les poudres à l'échelle d'un aliquot de 500 mg. [source]


Routine Analyses of Trace Elements in Geological Samples using Flow Injection and Low Pressure On-Line Liquid Chromatography Coupled to ICP-MS: A Study of Geochemical Reference Materials BR, DR-N, UB-N, AN-G and GH

GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001
Jean Carignan
géostandards; éléments traces; flow injection; chromatographie liquide; ICP-MS We describe analytical procedures for trace element determinations developed at the CNRS Service d'Analyse des Roches et des Minéraux (SARM) and report results obtained for five geochemical reference materials: basalt BR, diorite DR-N, serpentinite UB-N, anorthosite AN-G and granite GH. Results for rare earth elements, U and Th are also reported for other reference materials including dunite DTS-1, peridotite PCC-1 and basalt BIR-1. All rocks were decomposed using alkali fusion. Analyses were done by flow injection ICP-MS and by on-line low pressure liquid chromatography (LC)-ICP-MS for samples containing very low REE, U and Th concentrations. This latter method yielded limits of determination much lower than data by direct introduction and eliminated possible isobaric interference on these elements. Although results agree with most of the working values, when available, results for some elements differed slightly from the recommended concentrations. In these cases, we propose new values for Co, Y and Zn in basalt BR, Zr in diorite DR-N, Sr and U in granite GH, and Ga and Y in anorthosite AN-G. Furthermore, although the Sb concentration measured in AN-G was very close to our limit of determination, our value (0.3 ± 0.1 ,g g,1) is much lower than the reported working value of 1.4 ± 0.2 ,g g,1. These new values would need to be confirmed by a new inter-laboratory programme to further characterise these reference materials. Results obtained for REE, Th and U concentrations using the on-line low pressure LC-ICP-MS yielded good limits of determination (ng g,1to sub-ng g,1for rocks and ng l,1to sub-ng l,1for natural waters) and accurate results. The efficiency of the matrix separation allowed accurate measurements of Eu without the need to correct the BaO isobaric interference for samples having Ba/Eu ratios as high as 27700. For REE concentrations in PCC-1 and DTS-1, differences with values reported in the literature are interpreted as resulting from possible heterogeneity of the reference materials. Thorium and U values are proposed for these two samples, as well as for AN-G and UB-N. Nous rapportons les procédures d'analyse pour les éléments traces développées au Service d'Analyse des Roches et des Minéraux (SARM) du CNRS et les résultats obtenus pour 5 géostandards: le basalte BR, la diorite DR-N, la serpentinite UB-N, l'anorthosite AN-G et le granite GH. Des résultats obtenus pour les Terres Rares (REE), l'uranium et le thorium sont aussi rapportés pour d'autres matériaux de référence tels que la dunite DTS-1, la péridotite PCC-1 et le basalte BIR-1. Les roches ont été décomposées par fusion alcaline. Les analyses ont été faites par Flow Injection ICP-MS et par chromatographie liquide basse pression en ligne sur un ICP-MS pour les très faibles teneurs en REE, U et Th. Cette dernière méthode permet d'avoir une meilleure limite de détermination que celle par introduction directe et d'éliminer certaines interférences isobariques sur ces éléments. Bien que, dans la majorité des cas, nous ayons mesuré les valeurs de référence telles que rapportées dans la littérature, certaines concentrations mesurées diffèrent légèrement des valeurs recommandées. Ainsi, nous proposons de nouvelles valeurs de Co, Y et Zn pour le basalte BR, de Zr pour la diorite DR-N, de Sr et U pour le granite GH et de Ga et Y pour l'anorthosite AN-G. De plus, bien que la concentration en Sb mesurée pour AN-G soit très proche de notre limite de détermination, notre valeur (0.3 ± 0.1 ,g g,1) est bien inférieure à celle rapportée dans la littérature (1.4 ± 0.2 ,g g,1). Ces nouvelles valeurs devraient être confirmées par une nouvelle campagne de caractérisation inter laboratoire pour ces géostandards. Les résultats obtenus pour les REE, U et Th par chromatographie liquide basse pression en ligne sur un ICP-MS sont justes et livrent des limites de détermination faibles au niveau du ng g,1à sub-ng g,1pour les roches et ng l,1à sub-ng l,1pour les eaux naturelles. La séparation de la matrice est efficace et permet une mesure juste de Eu sans correction d'interférence générée par l'oxyde de Ba, et ce même pour des échantillons possédant des rapports Ba/Eu très élevés, de l'ordre de 27700. Les concentrations en REE mesurées pour les échantillons PCC-1 et DTS-1 peuvent être significativement différentes de celle rapportées dans la littérature, probablement à cause d'une hétérogénéité de ces échantillons. Des valeurs de concentrations en U et Th sont proposées pour ces deux échantillons ainsi que pour AN-G et UB-N. [source]


Rapid bioconcentration of steroids in the plasma of three-spined stickleback Gasterosteus aculeatus exposed to waterborne testosterone and 17,-oestradiol

JOURNAL OF FISH BIOLOGY, Issue 3 2007
R. J. Maunder
The relationship over time between the concentrations of two steroids, singly and in combination, in a static exposure system and in the blood of three-spined stickleback Gasterosteus aculeatus, held within the exposure system was investigated. Groups of three-spined stickleback were exposed (nominally) to either 1000 ng l,1 17,-oestradiol (E2), testosterone (T) or E2 and T in combination at the same concentrations for 6 days. Both water and fish were sampled at intervals and steroid concentrations in both compartments were determined. The plasma steroid time profile revealed a rapid bioconcentration within the first 6 h of exposure. The plasma steroid levels attained at this time point (20,90 ng ml,1) were up to 50-fold (E2) and 200-fold (T) greater than the actual levels of steroid measured in the exposure water, while levels in the blood of control fish did not exceed 4 ng ml,1. The substantial elevation of plasma steroid levels relative to the concentrations of steroid to which the fish were exposed in the ambient water gives scope for delivery of the steroids to target endocrine tissues at levels far in excess of what might be predicted on the basis of passive branchial uptake alone. These results are discussed in relation to endocrine disruption, and in particular the occurrence of effects in fish exposed to levels of endocrine active substances that are seemingly physiologically irrelevant. [source]


Cooperative biodegradation of geosmin by a consortium comprising three gram-negative bacteria isolated from the biofilm of a sand filter column

LETTERS IN APPLIED MICROBIOLOGY, Issue 4 2006
D. Hoefel
Abstract Aims:, To isolate and identify bacteria from a sand filter column capable of degrading the taste and odour compound, geosmin. In doing so, to investigate if these organisms degrade geosmin either individually or if an alternative mechanism is utilized. Methods and Results:, Geosmin-degrading bacteria from a biologically active sand filter column were enriched by their growth in a minimal medium supplemented with geosmin as the sole carbon source. By day 51, 21·7 mg l,1 of geosmin had been degraded as determined by solid-phase microextraction gas chromatography/mass spectrometry, and was accompanied by a 2·12 log10 increase in active bacterial numbers as measured using the BacLightTM bacterial viability kit and flow cytometric enumeration. During the onset of geosmin degradation, the predominance of three bacteria, most similar to previously cultured species of Sphingopyxis alaskensis, Novosphingobium stygiae and Pseudomonas veronii based on 16S rRNA gene sequences was detected by denaturing gradient gel electrophoresis. Subsequent isolation of these organisms revealed that degradation of geosmin, when present as either the sole carbon source (ranging from 40 ng l,1 to 20 mg l,1) or when spiked into sterile reservoir water (37 and 131 ng l,1), occurred only when all three isolates were present. None of the isolates was shown to be capable of degrading geosmin either individually or in any combination of two. Conclusions:, This study has reported, for the first time, the cooperative degradation of geosmin by a consortium comprising three gram-negative bacteria isolated from a biologically active sand filter column. Significance and Impact of the Study:, These results are important for researchers currently employing molecular-based approaches to further understand the biodegradation of geosmin by bacteria, as such studies may be complicated by the discovery of geosmin degradation occurring by a consortium. This study also advances the knowledge surrounding the types of bacteria capable of degrading the taste and odour compound, as investigations to date regarding this are limited. [source]


Plasma levels of dihydrotestosterone remain in the normal range in men treated with long-acting parenteral testosterone undecanoate

ANDROLOGIA, Issue 5 2007
A. A. Yassin
Summary The major goal of androgen therapy is to achieve testosterone levels as close to physiological concentrations as possible. For some androgen-dependent functions, testosterone is a pro-hormone, peripherally converted to 5,-dihydrotestosterone (DHT) and 17,-oestradiol of which the levels preferably should also be within their normal physiological ranges. In this study, the resulting plasma DHT levels in 122 hypogonadal men treated with a novel testosterone treatment modality: parenteral long-acting testosterone undecanoate (Nebido®), were investigated. Following the treatment, there were no abnormally high/low plasma DHT levels; levels varied between 86 and 511 ng l,1 (normal range: 40,575 ng l,1). In conclusion, treatment with testosterone undecanoate generates physiological levels of DHT. Prostate safety parameters did not undergo changes. [source]


Emission to air of volatile organotins from tributyltin-contaminated harbour sediments

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2002
Alfred J. Vella
Abstract An analytical method for determining the presence in air of volatile forms (e.g. chlorides) of tributyltin (TBT) and that of methylbutyltins MenBu(4,n)Sn (n,=,1,3) was developed and used to establish whether dredged harbour sediments contaminated with TBT served as sources of air pollution with respect to organotin compounds. The method was based on active sampling of the air being analysed and sorption of analytes onto Poropak-N. Sorbed methylbutyltins were extracted with dichloromethane and analysed by gas chromatography using flame photometric detection. Other butyltins were converted into butyltin hydrides prior to analysis by gas chromatography. It was shown that TBT-contaminated sediments from Marsamxett Harbour, Malta, placed in 0.5 l chambers through which air was displaced by continuous pumping for 11 days released mainly methylbutyltins, with concentrations (as tin) reaching maximum 48,h mean values of 8.7 (Me3BuSn), 22.1 (Me2Bu2Sn) and 93.0,ng m,3(MeBu3Sn) being measured. Other volatile forms of TBT, dibutyltin and monobutyltin were detected in the headspace air, but very infrequently and at much lower tin concentrations (<2,ng m,3). It was also shown that methylbutyltins dissolved in sea-water ([Sn],=,0.2 to 400,ng l,1) were very difficult to exsolve from this medium, even on prolonged evaporation of the solutions using mechanical agitation and active ventilation. The results suggest that emission of methylbutyltins from contaminated sediments probably occurs only from the surface of the material. The environmental implications of these findings in the management of TBT-polluted harbour sediments are discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Glucagon is absorbed from the rectum but does not hasten recovery from hypoglycaemia in patients with type 1 diabetes

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 1 2008
David R. Parker
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Patients with type 1 diabetes experience recurrent hypoglycaemia and have abnormal glucose counter regulatory responses with a failure to secrete glucagon. It is unknown if rectal glucagon is absorbed and what effect this may have on counter regulation from hypoglycaemia. WHAT THIS STUDY ADDS , A rectal suppository of glucagon results in a rise in plasma glucagon with metabolic effects in normal subjects. Similarly rectal glucagon results in a rise in plasma glucagon in patients with type 1 diabetes, but 1 mg does not improve recovery rates from experimental hypoglycaemia when compared with placebo. , Larger doses of glucagon per rectum may provide pharmacological circulating concentrations with resulting therapeutic benefit during recovery from hypoglycaemia and deserves further study. AIMS A failure to secrete glucagon during hypoglycaemia is near universal in patients with type 1 diabetes 5 years after disease onset and may contribute to delayed counter-regulation during hypoglycaemia. Rectal glucagon delivery may assist glucose recovery following insulin-induced hypoglycaemia in such patients and has not been previously studied. METHODS Six male patients (age 21,38 years) with type 1 diabetes (median duration 10 years) without microvascular complications, were studied supine after an overnight fast on two separate occasions at least 14 days apart. After omission of their usual morning insulin and 45 min rest, hypoglycaemia was induced by an intravenous insulin infusion which was terminated when capillary glucose concentration reached 2.5 mmol l,1. Subjects were randomized to insert a rectal suppository containing 100 mg indomethacin alone (placebo) or 100 mg indomethacin plus 1 mg glucagon at the hypoglycaemic reaction. Serial measurements were made for 120 min. RESULTS In the two groups, mean (SD) plasma glucose concentrations fell to a similar nadir of 1.8 (0.7) mmol l,1 (placebo) and 2.1 (1.2) mmol l,1 (glucagon). Peak plasma glucagon following hypoglycaemia was higher in the glucagon group; 176 (32) ng l,1vs. 99 (22) ng l,1 after placebo (P = 0.006). However, the glucose recovery rate over 120 min after hypoglycaemia did not differ significantly. CONCLUSIONS Our results provide evidence for the absorption of glucagon from the rectum. They also indicate that 1 mg does not constitute a useful mode of therapy to hasten recovery from hypoglycaemia in patients with type 1 diabetes. [source]


Clinical signs of heart failure are associated with increased levels of natriuretic peptide types B and A in children with congenital heart defects or cardiomyopathy

ACTA PAEDIATRICA, Issue 3 2004
A Westerlind
Aim: To study whether natriuretic peptide types B (BNP) and A (ANP) reflect clinical signs of heart failure (CSHF) in children with congenital heart defects or cardiomyopathy resulting in different types of haemodynamic situations, such as pressure overload in coarctation of the aorta (CoA), volume overload in ventricular septal defect (VSD) or systolic dysfunction in dilated cardiomyopathy (DCM). Methods: Blood samples for plasma P-BNP and P-ANP were taken before procedures during regular investigation from 26 children (9 CoA, 11 VSD and 6 DCM). The ordinary paediatric cardiologist performed the cardiac evaluation and the data were retrieved from medical charts. CSHF was considered positive if two of the following criteria were fulfilled: reduced physical capacity, feeding disorders, dyspnoea, tachypnoea, hepatomegaly and oedema. The statistical methods were non-parametric. Results: 0/9 children with CoA, 5/11 with VSD and 6/6 with DCM had CSHF. In children with CSHF, P-BNP and P-ANP were higher, 263 ng l,1 (range 47.5,1300) and 303 ng l,1 (range 168,466), than in those without CSHF, 12.3 ng l,1 (range 4.8,30.8) and 42.9 ng l1 (range 13.7,189), respectively (p < 0.001, Mann-Whitney U-test), irrespective of the diagnosis. The same relationship was also found in the group of children with VSD. Conclusion: Plasma levels of ANP and BNP increase in children with CSHF. This increase is seen irrespective of whether it is due to systolic dysfunction, as in children with DCM, or to a volume overload with a normal systolic function, as in children with VSD. [source]


Increased plasma levels of natriuretic peptide type B and A in children with congenital heart defects with left compared with right ventricular volume overload or pressure overload

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2005
Daniel Holmgren
Summary Aim:, Natriuretic peptide levels B (BNP) and A (ANP) have been described in children with congenital heart defects (CHD) with pressure and volume overload. However, the impact of ventricular morphology per se on natriuretic peptide levels has not been reported. The aim of the present study was to evaluate plasma BNP and ANP in children with CHD with left or right ventricular volume or pressure overload. Methods and results:, Plasma BNP and ANP were analysed in 61 children, median age 3·1 (0·3,16·2) years. Haemodynamic load was evaluated by echo-Doppler and/or catheterization measurements and classified as: pressure overload of the right (RV pressure) or left (LV pressure) ventricle, or volume overload of the right (RV volume) or left (LV volume) ventricle, of a sufficient degree to indicate surgery/catheter intervention. Twenty-three children, with a median age of 1·1 (0·1,8·3) years, without heart disease, served as controls for the natriuretic peptide measurements. Children in the LV volume group had significantly higher BNP and ANP values, 55·4 ng l,1 (10·7,352) and 164 (31·8,346), than children in the RV volume, 15·6 (0·0,105·1) and 57·2 (11·3,234·1), LV pressure, 6·8 (0·7,170) and 40·8 (12·6,210), and RV pressure, 18·0 (5·0,29·1) and 69·3 (8·7,182), groups respectively (P<0·0001). The values in the LV pressure group were close to the values in the Control group, 4·7 (0·0,17·7) and 32·9 (11·7,212·1), respectively (P = 0·051 and P = 0·378, respectively). Conclusions:, Plasma concentrations of BNP and ANP were higher in children with CHD with left ventricular volume overload compared with right ventricular volume overload or pressure overload. [source]