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Selenium (Se) is an essential element for most eukaryotic organisms, including humans. The balance between Se toxicity and its beneficial effects is very delicate. It has been demonstrated that a diet enriched with Se has cancer prevention potential in humans. The most popular commercial Se supplementation is selenized yeast, which is produced in a fermentation process using an inorganic source of Se. Here, we show that the uptake of Se, Se toxic effects and intracellular Se-metabolite profile are largely influenced by the level of sulphur source supplied during the fermentation. A Yap1-dependent oxidative stress response is active when yeast actively metabolizes Se, and this response is linked to the generation of intracellular redox imbalance. The redox imbalance derives from a disproportionate ratio between the reduced and oxidized forms of glutathione and also from the influence of Se metabolism on the central carbon metabolism. The observed increase in glycerol production rate, concomitant with the inhibition of ethanol formation in the presence of Se, can be ascribed to the occurrence of redox imbalance that triggers glycerol biosynthesis to replenish the pool of NAD+. [ABSTRACT FROM AUTHOR]

The selenium salt selenite (SeO32-) is cytotoxic in low to moderate concentrations, with a remarkable specificity for cancer cells resistant to conventional chemotherapy. Our data show that selenium uptake and accumulation, rather than intracellular events, are crucial to the specific selenite cytotoxicity observed in resistant cancer cells. We show that selenium uptake depends on extracellular reduction, and that the extracellular environment is a key factor specific to selenite cytotoxicity. The extracellular reduction is mediated by cysteine. and the efficacy is determined by the uptake of cystine by the xc-antiporter and secretion of cysteine by multidrug resistance proteins, both of which are frequently overexpressed by resistant cancer cells. This mechanism provides molecular evidence for the existence of an inverse relationship between resistance to conventional chemotherapy and sensitivity to selenite cytotoxicity, and highlights the great therapeutic potential in treating multidrug-resistant cancer. [ABSTRACT FROM AUTHOR]

Increased Se intakes have been associated with decreased risk of cancer and CVD. Several mechanisms have been proposed, including antioxidant effects through selenoproteins, induction of carcinogen metabolism and effects on the blood lipid profile. In a 4??????1 week randomised, double-blind cross-over study, healthy young men supplemented their usual diet with selenate, Se-enriched yeast, Se-enriched milk or placebo (Se dose was 300????g/d for selenate and Se-enriched yeast, and about 480????g/d for Se-enriched milk) followed by 8-week washout periods. All Se sources increased serum Se levels after supplementation for 1 week. The effect of the organic forms did not differ significantly and both increased serum Se more than selenate. Conversely, thrombocyte glutathione peroxidase (GPX) was increased in the periods where subjects were supplemented with selenate but not in those where they were given Se-enriched yeast or Se-enriched milk. We found no effect on plasma lipid resistance to oxidation, total cholesterol, TAG, HDL- and LDL-cholesterol, GPX, glutathione reductase (GR) and glutathione S-transferase (GST) activities measured in erythrocytes, GPX and GR activities determined in plasma, or GR and GST activities in thrombocytes. Leucocyte expression of genes encoding selenoproteins (GPX1, TrR1 and SelP), and of electrophile response element-regulated genes (GCLC, Fra1 and NQO1) were likewise unaffected at all time points following intervention. We conclude that thrombocyte GPX is specifically increased by short-term selenate supplementation, but not by short-term supplementation with organic Se. Short-term Se supplementation does not seem to affect blood lipid markers or expression and activity of selected enzymes and a transcription factor involved in glutathione-mediated detoxification and antioxidation. [ABSTRACT FROM PUBLISHER]

Objective: The purpose of this study was to evaluate the pharmacokinetics of a single dose of selenium (Se) from yeast given to humans with a habitual long-term daily intake at a supra-nutritional level. Methods: Twelve healthy males with a daily supplemental intake of 300 mg Se as selenised yeast over 10 weeks were supplemented with a single dose of 327 μg as stable 77Se incorporated into selenised yeast manufactured by the same standardised process (SelenoPrecise®, Pharma Nord, Denmark). Results: Absorption of Se from 77Se-enriched yeast was 89±4% and the retention was 74±6%. The 77Se excretion from the single-dose was 47±15 μg in urine and 37±13 μg in faeces. The maximum, enriched 77Se concentration in plasma was 9.8±1.5 ±g/l and the time to maximum was 9.2 hours. The plasma halftime of 77Se was longer with increasing time; 1.7 days for the initial phase (½-2 days), 3.0 days for the middle phase (2-3 days) and 11.1 days for the later phase (3-14 days). Conclusion: The Se from the standardised Se-enriched yeast was well absorbed and retained in the body. [ABSTRACT FROM AUTHOR]

Reports on a study which showed that selenomethionine is predominant in the sample hydrolysates. Investigation of the speciation and bioavailability of selenium in yeast-based intervention agents from multiple manufacturers from several time points.

Abstract: Unborn children are exposed to environmental pollutants via the placenta, and there is a causal relationship between maternal intake of pollutants and fetal exposure. Placental examination is an effective way for acquiring data for estimating fetal exposure. We analyzed the concentrations of 104 congeners of persistent organic pollutants, seven organotin compounds, five heavy metals, and methylmercury in 130 randomly selected placentas. Additionally, we examined similarities between pollutant concentrations by analyzing correlations between their placental concentrations. Our results yield new information for conducting contaminant risk assessments for the prenatal period. Out of the 117 individual persistent organic pollutants or metals assayed, 46 could be detected in more than half of the placentas. Moreover, dichlorodiphenyldichloroethylene (p,p′-DDE) was found in all placentas. The data indicates that fetal exposure to dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), p,p′-DDE, and methylmercury depends on the mother’s parity, and age. We also conclude that sources of the above four pollutants are similar but differ from the sources of polybrominated diphenyl ethers. [Copyright &y& Elsevier]

Abstract: Asymmetric flow field-flow fractionation (AF4) in combination with on-line optical detection and mass spectrometry is one of the most promising methods for separation and quantification of nanoparticles (NPs) in complex matrices including food. However, to obtain meaningful results regarding especially the NP size distribution a number of parameters influencing the separation need to be optimized. This paper describes the development of a separation method for polyvinylpyrrolidone-stabilized silver nanoparticles (AgNPs) in aqueous suspension. Carrier liquid composition, membrane material, cross flow rate and spacer height were shown to have a significant influence on the recoveries and retention times of the nanoparticles. Focus time and focus flow rate were optimized with regard to minimum elution of AgNPs in the void volume. The developed method was successfully tested for injected masses of AgNPs from 0.2 to 5.0μg. The on-line combination of AF4 with detection methods including ICP-MS, light absorbance and light scattering was helpful because each detector provided different types of information about the eluting NP fraction. Differences in the time-resolved appearance of the signals obtained by the three detection methods were explained based on the physical origin of the signal. Two different approaches for conversion of retention times of AgNPs to their corresponding sizes and size distributions were tested and compared, namely size calibration with polystyrene nanoparticles (PSNPs) and calculations of size based on AF4 theory. Fraction collection followed by transmission electron microscopy was performed to confirm the obtained size distributions and to obtain further information regarding the AgNP shape. Characteristics of the absorbance spectra were used to confirm the presence of non-spherical AgNP. [Copyright &y& Elsevier]

Abstract: PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium–aluminum layered double hydroxide (Mg-Al-LDH-C12), the corresponding carbonate form (Mg-Al-LDH-CO3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer surfaces and catalytically active Mg site centers are causative factors for PLA degradation. Interestingly, the release of water under the processing conditions was found to have a rather small effect on the PLA degradation. Low loadings of sodium laurate also caused PLA degradation indicating that carboxylate chain ends may be active degrading agents. Phosphate treatment of laurate-modified LDH was investigated and this may be a promising way of reducing PLA degradation, thereby making such processes more practically realistic. [Copyright &y& Elsevier]

Abstract: The aims were to bio-fortify onions by foliar application of selenium (Se) and to intrinsically label bioactive Se-metabolites in onion and carrot by enriched, stable 77Se for use in human physiological studies. Onion bulbs and leaves were enriched in Se by repeated foliar spraying of 10 or 100μgSeml−1 solutions of sodium selenite (Se(IV)) or sodium selenate (Se(VI)). ICP-MS analysis of onion leaves and bulbs showed that the Se concentration was enhanced by up to a factor of approximately 50 and 200 in bulbs and leaves, respectively. HPLC–ICP-MS analysis of proteolytic plant extracts showed that foliar application of Se(IV) gave rise to bio-synthesis of a higher fraction of the desired organic Se species and was better tolerated by the plants than Se(VI). Based on these findings onions and carrots were bio-fortified by foliar application of a solution of 77Se(IV) that was enriched to 99.7% as 77Se. The 77Se- labelled metabolites in onions were predominantly γ-glutamyl-77Se-selenomethyl-selenocysteine (γ-glu-Me77SeCys), 77Se-methylselenocysteine (Me77SeCys) and 77Se-selenomethionine (77SeMet). Furthermore, we report here for the first time the finding in carrots of the bioactive Me77SeCys, the identity of which was verified by HPLC–ESI-MS/MS. [Copyright &y& Elsevier]

Abstract: We compared the neurotoxic effects of 14nm silver nanoparticles (AgNPs) and ionic silver, in the form of silver acetate (AgAc), in vivo and in vitro. In female rats, we found that AgNPs (4.5 and 9mg AgNP/kg bw/day) and ionic silver (9mg Ag/kg bw/day) increased the dopamine concentration in the brain following 28 days of oral administration. The concentration of 5-hydroxytryptamine (5-HT) in the brain was increased only by AgNP at a dose of 9mg Ag/kg bw/day. Only AgAc (9mg Ag/kg bw/day) was found to increase noradrenaline concentration in the brain. In contrast to the results obtained from a 28-day exposure, the dopamine concentration in the brain was decreased by AgNPs (2.25 and 4.5mg/kg bw/day) following a 14-day exposure. These data suggest that there are differential effects of silver on dopamine depending on the length of exposure. In vitro, AgNPs, AgAc and a 12kDa filtered sub-nano AgNP fraction were used to investigate cell death mechanisms in neuronal-like PC12 cells. AgNPs and the 12kDa filtered fraction decreased cell viability to a similar extent, whereas AgAc was relatively more potent. AgNPs did not induce necrosis. However, apoptosis was found to be equally increased in cells exposed to AgNPs and the 12kDa filtered fraction, with AgAc showing a greater potency. Both the mitochondrial and the death receptor pathways were found to be involved in AgNP- and AgAc-induced apoptosis. In conclusion, 14nm AgNPs and AgAc affected brain neurotransmitter concentrations. AgNP affected 5-HT, AgAc affected noradrenaline, whereas both silver formulations affected dopamine. Furthermore, apoptosis was observed in neuronal-like cells exposed to AgNPs, a 12kDa filtered fraction of AgNP, and AgAc. These findings suggest that ionic silver and a 14nm AgNP preparation have similar neurotoxic effects; a possible explanation for this could be the release and action of ionic silver from the surface of AgNPs. [Copyright &y& Elsevier]

Abstract: Dose escalation in prostate radiotherapy is limited by normal tissue toxicities. The aim of this study was to assess the impact of margin size on tumor control and side effects for intensity-modulated radiation therapy (IMRT) and 3D conformal radiotherapy (3DCRT) treatment plans with increased dose. Eighteen patients with localized prostate cancer were enrolled. 3DCRT and IMRT plans were compared for a variety of margin sizes. A marker detectable on daily portal images was presupposed for narrow margins. Prescribed dose was 82 Gy within 41 fractions to the prostate clinical target volume (CTV). Tumor control probability (TCP) calculations based on the Poisson model including the linear quadratic approach were performed. Normal tissue complication probability (NTCP) was calculated for bladder, rectum and femoral heads according to the Lyman-Kutcher-Burman method. All plan types presented essentially identical TCP values and very low NTCP for bladder and femoral heads. Mean doses for these critical structures reached a minimum for IMRT with reduced margins. Two endpoints for rectal complications were analyzed. A marked decrease in NTCP for IMRT plans with narrow margins was seen for mild RTOG grade 2/3 as well as for proctitis/necrosis/stenosis/fistula, for which NTCP <7% was obtained. For equivalent TCP values, sparing of normal tissue was demonstrated with the narrow margin approach. The effect was more pronounced for IMRT than 3DCRT, with respect to NTCP for mild, as well as severe, rectal complications. [Copyright &y& Elsevier]

Abstract: Specific Se-metabolites have been recognized to be the main elements responsible for beneficial effects of Se-enriched diet, and Se-methylselenocysteine (SeMCys) is thought to be among the most effective ones. Here we show that an engineered Saccharomyces cerevisiae strain, expressing a codon optimized heterologous selenocysteine methyltransferase and endowed with high intracellular levels of S-adenosyl-methionine, was able to accumulate SeMCys at levels higher than commercial selenized yeasts. A fine tuned carbon- and sulfate-limited fed-batch bioprocess was crucial to achieve good yields of biomass and SeMCys. Through the coupling of metabolic and bioprocess engineering we achieved a ∼24-fold increase in SeMCys, compared to certified reference material of selenized yeast. In addition, we investigated the interplay between sulfur and selenium metabolism and the possibility that redox imbalance occurred along with intracellular accumulation of Se. Collectively, our data show how the combination of metabolic and bioprocess engineering can be used for the production of selenized yeast enriched with beneficial Se-metabolites. [Copyright &y& Elsevier]

Abstract: The thorough analysis of natural nanoparticles (NPs) and engineered NPs involves the sequence of detection, identification, quantification and, if possible, detailed characterization. In a complex or heterogeneous sample, each step of this sequence is an individual challenge, and, given suitable sample preparation, field-flow fractionation (FFF) is one of the most promising techniques to achieve relevant characterization. The objective of this review is to present the current status of FFF as an analytical separation technique for the study of NPs in complex food and environmental samples. FFF has been applied for separation of various types of NP (e.g., organic macromolecules, and carbonaceous or inorganic NPs) in different types of media (e.g., natural waters, soil extracts or food samples). FFF can be coupled to different types of detectors that offer additional information and specificity, and the determination of size-dependent properties typically inaccessible to other techniques. The separation conditions need to be carefully adapted to account for specific particle properties, so quantitative analysis of heterogeneous or complex samples is difficult as soon as matrix constituents in the samples require contradictory separation conditions. The potential of FFF analysis should always be evaluated bearing in mind the impact of the necessary sample preparation, the information that can be retrieved from the chosen detection systems and the influence of the chosen separation conditions on all types of NP in the sample. A holistic methodological approach is preferable to a technique-focused one. [Copyright &y& Elsevier]

This study investigated whether game meat may contain nanoparticles of lead from ammunition. Lead nanoparticles in the range 40 to 750 nm were detected by ICP-MS in single particle mode in game shot with lead-containing bullets. The median diameter of the detected nanoparticles was around 60 nm. The particle mass concentration ranged from 290 to 340 ng/g meat and the particle number concentrations from 27 to 50 million particles/g meat. The size limit of detection strongly depended on the level of dissolved lead and was in the range of 40 to 80 nm. In game meat sampled more than 10 cm away from the wound channel, no lead particles with a diameter larger than 40 nm were detected. In addition to dissolved lead in meat that originated from particulates, the presence of lead nano particles in game meat represents a hitherto unattended source of lead with a largely unknown toxicological impact to humans. Graphical Abstract Detection of lead nanoparticles in game meat by single particle ICP-MS following use of leadcontaining bullets.

Background: Sodium selenite at high dose exerts antitumor effects and increases efficacy of cytostatic drugs in multiple preclinical malignancy models. We assessed the safety and efficacy of intravenous administered sodium selenite in cancer patients' refractory to cytostatic drugs in a phase I trial. Patients received first line of chemotherapy following selenite treatment to investigate altered sensitivity to these drugs and preliminary assessment of any clinical benefits., Materials and Methods: Thirty-four patients with different therapy resistant tumors received iv sodium selenite daily for consecutive five days either for two weeks or four weeks. Each cohort consisted of at least three patients who received the same daily dose of selenite throughout the whole treatment. If 0/3 patients had dose-limiting toxicities (DLTs), the study proceeded to the next dose-level. If 2/3 had DLT, the dose was considered too high and if 1/3 had DLT, three more patients were included. Dose-escalation continued until the maximum tolerated dose (MTD) was reached. MTD was defined as the highest dose-level on which 0/3 or 1/6 patients experienced DLT. The primary endpoint was safety, dose-limiting toxic effects and the MTD of sodium selenite. The secondary endpoint was primary response evaluation., Results and Conclusion: MTD was defined as 10.2 mg/m(2), with a calculated median plasma half-life of 18.25 h. The maximum plasma concentration of selenium from a single dose of selenite increased in a nonlinear pattern. The most common adverse events were fatigue, nausea, and cramps in fingers and legs. DLTs were acute, of short duration and reversible. Biomarkers for organ functions indicated no major systemic toxicity. In conclusion, sodium selenite is safe and tolerable when administered up to 10.2 mg/m(2) under current protocol. Further development of the study is underway to determine if prolonged infusions might be a more effective treatment strategy.

Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co or other elements, but the current analytical methods used to investigate the processes involved do not provide sufficient information to understand the size or composition of the wear particles generated in vivo. In this qualitative feasibility study, asymmetric flow field-flow fractionation (AF(4)) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate metal protein binding and the size and composition of wear metal particles present in serum and hip aspirates from MoM hip replacement patients. A well-established HPLC anion exchange chromatography (AEC) separation system coupled to ICP-MS was used to confirm the metal-protein associations in the serum samples. Off-line single particle ICP-MS (spICP-MS) analysis was used to confirm the approximate size distribution indicated by AF(4) of the wear particles in hip aspirates. In the serum samples, AF(4) -ICP-MS suggested that Cr was associated with transferrin (Tf) and Co with albumin (Alb) and an unidentified species; AEC-ICP-MS confirmed these associations and also indicated an association of Cr with Alb. In the hip aspirate sample, AF(4)-ICP-MS suggested that Cr was associated with Alb and Tf and that Co was associated with Alb and two unidentified compounds; AEC analysis confirmed the Cr results and the association of Co with Alb and a second compound. Enzymatic digestion of the hip aspirate sample, followed by separation using AF(4) with detection by UV absorption (280 nm), multi-angle light scattering and ICP-MS, suggested that the sizes of the Cr-, Co- and Mo-containing wear particles in a hip aspirate sample were in the range 40-150 nm. Off-line spICP-MS was used to confirm these findings for the Co- and Cr-containing nanoparticles. Whilst limited in scope, the results are sufficient to show the interaction of ions with transport proteins and give an indication of particle size, providing useful pathological indices. As such, the methods indicate a new way forward for in vivo investigation of the processes which lead to tissue necrosis and hip loosening in patients with MoM hip replacements.

Background: In Graves' thyrotoxicosis tachycardia, weight loss and mental symptoms are common. Recovery takes time and varies between patients. Treatment with methimazole reduces thyroid hormone levels. According to previous research, this reduction has been faster if selenium (Se) is added., Objective: The objective was to investigate whether supplementing the pharmacologic treatment with Se could change the immune mechanisms, hormone levels and/or depression and anxiety., Methods: We prospectively investigated 38 patients with initially untreated thyrotoxicosis by measuring the thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), thyroid receptor antibodies and thyroid peroxidase auto-antibodies before medication and at 6, 18 and 36 weeks after commencing treatment with methimazole and levo-thyroxine, with a randomized blinded oral administration of 200 µg Se/day or placebo. The selenoprotein P concentration was determined in plasma at inclusion and after 36 weeks. The patients were also assessed with questionnaires about depression, anxiety and self-rated symptoms before medication was started and after 36 weeks., Results: FT4 decreased more in the Se group at 18 weeks (14 vs. 17 pmol/l compared to the placebo group, p = 0.01) and also at 36 weeks (15 vs. 18 pmol/l, p = 0.01). The TSH increased more in the Se group at 18 weeks (0.05 vs. 0.02 mIU/l, p = 0.04). The depression and anxiety scores were similar in both groups. In the Se group, the depression rates correlated negatively with FT3 and positively with TSH. This was not seen in the placebo group., Conclusions: Se supplementation can enhance biochemical restoration of hyperthyroidism, but whether this could shorten clinical symptoms of thyrotoxicosis and reduce mental symptoms must be investigated further.

Inductively coupled plasma mass spectrometry in single-particle mode (spICPMS) is a promising method for the detection of metal-containing nanoparticles (NPs) and the quantification of their size and number concentration. Whereas existing studies mainly focus on NPs suspended in aqueous matrices, not much is known about the applicability of spICPMS for determination of NPs in complex matrices such as biological tissues. In the present study, alkaline and enzymatic treatments were applied to solubilize spleen samples from rats, which had been administered 60-nm gold nanoparticles (AuNPs) intravenously. The results showed that similar size distributions of AuNPs were obtained independent of the sample preparation method used. Furthermore, the quantitative results for AuNP mass concentration obtained with spICPMS following alkaline sample pretreatment coincided with results for total gold concentration obtained by conventional ICPMS analysis of acid-digested tissue. The recovery of AuNPs from enzymatically digested tissue, however, was approximately four times lower. Spiking experiments of blank spleen samples with AuNPs showed that the lower recovery was caused by an inferior transport efficiency of AuNPs in the presence of enzymatically digested tissue residues.

A method of analysis of silver nanoparticles (AgNPs) in chicken meat was developed. The homogenized chicken meat sample, which was spiked with AgNPs, was subjected to enzymolysis by Proteinase K for 40 min at 37 °C. Transmission electron microscopy and inductively coupled plasma mass spectrometry (ICP-MS) in single particle mode were used to characterize the number-based size distribution of AgNPs in the meat digestate. Because similar size distributions were found in the meat digestate and in the aqueous suspension of AgNPs used for spiking the meat, it was shown that no detectable dissolution of the AgNPs took place during the sample preparation stage. The digestate was injected into the asymmetric flow field flow fractionation (AF(4)) -ICP-MS system, which enabled fractionation of nanoparticles from the remaining meat matrix, and resulted in one large peak in the fractograms as well as two smaller peaks eluting close to the void volume. The recovery of silver contained in the large AgNP peak was around 80%. Size determination of AgNPs in the meat matrix, based on external size calibration of the AF(4) channel, was hampered by non-ideal (early elution) behavior of the AgNPs. Single particle ICP-MS was applied for determination of the number-based particle size distribution of AgNPs in collected fractions. The presented work describes for the first time the coupling of AF(4) and ICP-MS for AgNP separation in a food matrix.

Agricultural methods may affect the nutritional composition of plants and cause complex changes in the food matrix. Whether this affects the dietary absorption of minerals that are important for maintaining health thorough life remains unclear. We compared the effects of organic and conventional diets on intake and absorption of zinc and copper in men. Two double-blinded, cross-over, intervention trials (3 dietary periods of 12 days with 2-week-long wash-out) were performed in 2008 (n = 17) and 2009 (n = 16) in young men. The diets were based on 9 crops grown in rigidly controlled organic and conventional systems in 2 replications over 2 years. The primary outcomes were intake and absorption of zinc and copper. The absorption was determined by faecal excretion of stable enriched isotopes extrinsically added to the entire menu. Within each year, the intake and absorption of zinc (overall mean ± SD; 12.35 ± 0.47 mg per 10 MJ and 44.6% ± 12.1, respectively) and copper (overall mean ± SD; 2.12 ± 0.28 mg per 10 MJ and 41.2% ± 13.2, respectively) were not different between the organic and conventional diets. The growing season had no effect on zinc intake and absorption, but the copper intake was higher (P = 0.01) and absorption lower (P < 0.005) in 2008 compared with 2009 (overall mean absorption ± SD; 35.3% ± 13.5 in 2008 and 54.0% ± 10.7 in 2009). In conclusion, organic agriculture does not affect the intake and absorption of copper and zinc in men. Consequently, it does not seem to promote the health beneficial role of these minerals in vivo.

The present paper describes a novel method for the quantitative determination of inorganic arsenic (iAs) in food and feed of marine origin. The samples were subjected to microwave-assisted extraction using diluted hydrochloric acid and hydrogen peroxide, which solubilised the analytes and oxidised arsenite (As(III)) to arsenate (As(V)). Subsequently, a pH buffering of the sample extract at pH 6 enabled selective elution of As(V) from a strong anion exchange solid-phase extraction (SPE) cartridge. Hydride generation atomic absorption spectrometry (HG-AAS) was applied to quantify the concentration of iAs (sum of As(III) and As(V)) as the total arsenic (As) in the SPE eluate. The results of the in-house validation showed that mean recoveries of 101-104% were achieved for samples spiked with iAs at 0.5, 1.0 and 1.5 mg·kg(-1), respectively. The limit of detection was 0.08 mg kg(-1), and the repeatability (RSD(r)) and intra-laboratory reproducibility (RSD(IR)) were less than 8% and 13%, respectively, for samples containing 0.2 to 1.5 mg kg(-1) iAs. The trueness of the SPE HG-AAS method was verified by confirming results obtained by parallel analysis using high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry. It was demonstrated that the two sets of results were not significantly different (P < 0.05). The SPE HG-AAS method was applied to 20 marine food and feed samples, and concentrations of up to 0.14 mg kg(-1) of iAs were detected.

Subacute toxicity of 14 nm nanoparticulate silver (Ag-NP) stabilised with polyvinylpyrrolidone and ionic silver in the form of silver acetate (Ag-acetate) was investigated in four-week-old Wistar rats. Animals received orally by gavage the following: vehicle control (10 ♀, 6 ♂); Ag-NP at doses: 2.25 (8 ♀), 4.5 (8 ♀) or 9 mg/kg bw/day (10 ♀, 6 ♂); or Ag-acetate 9 mg silver/kg bw/day (8 ♀) for 28 days. Clinical, haematolological and biochemical parameters, organ weights, macro- and microscopic pathological changes were investigated. Caecal bacterial phyla and their silver resistance genes were quantified. For the Ag-NP groups, no toxicological effects were recorded. For Ag-acetate, lower body weight gain (day 4-7, 11-14, 14-16, P < 0.05; overall, day 1-28, P < 0.01), increased plasma alkaline phosphatase (P < 0.05), decreased plasma urea (P < 0.05) and lower absolute (P < 0.01) and relative (P < 0.05) thymus weight were recorded. In conclusion, these findings indicate toxicity of 9 mg/kg bw/day ionic silver but not of an equimolar Ag-NP dose. This is in accordance with previously reported data showing that oral Ag-acetate, in comparison with an equimolar dose of Ag-NP, resulted in higher silver plasma and organ concentrations.

Selenium is a candidate treatment for liver tumour prevention in chronic liver disease. In this study, we have studied selenium uptake, distribution and accumulation in rats provided with water containing tumour-preventive doses of sodium selenite for 10 weeks. Male Fischer 344 rats were given drinking water containing 1 μg/mL or 5 μg/mL sodium selenite. Selenium levels were monitored in serum and liver tissue over the 10-week period, and the kinetics of induction of the redox-active cytosolic selenoenzyme thioredoxin reductase were followed. Selenite exposure via drinking water caused a dose-dependent increase in blood and liver selenium levels, with plateaus at 6 and 8 weeks, respectively. These plateaus were reached at the same level of selenium regardless of dose, and no further accumulation was observed. A selenium-dependent increase in the activity of TrxR1 in parallel with the increase in liver selenium levels was also seen, and the induction of TrxR1 mRNA was seen only during the first three days of treatment, when the levels of selenium in the liver were increasing. Sodium selenite at 1 and 5 μg/mL did not affect body weight or relative liver mass. We concluded that long-term treatment with selenite did not cause accumulation of selenium and that the activity of TrxR1 in the liver rose with the selenium levels. We therefore suggest that sodium selenite at doses up to 5 μg/mL could be used for long-term tumour prevention., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb's oxidation state. The most commonly applied chromatographic methods used for this redox speciation analysis do, however, often show a low chromatographic Sb recovery when samples of environmental or biological origin are analysed. In this study we explored basal chemistry of antimony and found that formation of macromolecules, presumably oligomeric and polymeric Sb(V) species, is the primary cause of low chromatographic recoveries. A combination of HPLC-ICP-MS, AFFF-ICP-MS and spin-filtration was applied for analysis of model compounds and biological samples. Quantitative chromatographic Sb redox speciation analysis was possible by acidic hydrolysis of the antimony polymers prior to analysis. Sample treatment procedures were studied and the optimum solution was acidic hydrolysis by 1 M HCl in the presence of chelating ligands (EDTA, citrate), which stabilise the trivalent oxidation state of Sb.

Epidemiological investigations document that workers in agriculture, horticulture and people living near areas with frequent use of pesticides have increased risk of developing symptoms of Parkinson's disease. This study investigated the neurotoxic effect of the fungicide maneb by morphological, immunohistochemical and neurochemical methods applying young Sprague-Dawley male rat as the model. Intraperitoneal dosing (7.5, 15 or 30mg maneb/kg bodyweight/week for 12 weeks) demonstrated dose-related increased manganese concentration in corpus striatum. The striatal concentration of 5-hydroxytryptamine (5-HT) increased in a dose-related manner, as did the 5-HT concentrations in the rest of the brain indicating early sign of neurotoxicity. Striatal acetylcholinesterase activity was not affected. The concentrations of noradrenaline, dopamine, neurotransmitter amino acids and the levels of the proteins α-synuclein and synaptophysin in corpus striatum and the rest of the brain were not changed. No histological parameter was affected when studied in corpus striatum and substantia nigra.

A method for the determination of inorganic arsenic in seafood samples using high-performance liquid chromatography-inductively coupled plasma mass spectrometry is described. The principle of the method relied on microwave-assisted alkaline dissolution of the sample, which at the same time oxidized arsenite [As(III)] to arsenate [As(V)], whereby inorganic arsenic could be determined as the single species As(V). Anion exchange chromatography using isocratic elution with aqueous ammonium carbonate as the mobile phase was used for the separation of As(V) from other coextracted organoarsenic compounds, including arsenobetaine. The stability of organoarsenic compounds during the sample pretreatment was investigated, and no degradation/conversion to inorganic arsenic was detected. The method was employed for the determination of inorganic arsenic in a variety of seafood samples including fish, crustaceans, bivalves, and marine mammals as well as a range of marine certified reference materials, and the results were compared to values published in the literature. For fish and marine mammals, the results were in most cases below the limit of detection. For other sample types, inorganic arsenic concentrations up to 0.060 mg kg(-)(1) were found. In all samples, the inorganic arsenic content constituted less than 1% of the total arsenic content.

An analytical method for the determination of inorganic arsenic in fish samples using HPLC-ICP-MS has been developed. The fresh homogenised sample was subjected to microwave-assisted dissolution by sodium hydroxide in ethanol, which dissolved the sample and quantitatively oxidised arsenite (As(III)) to arsenate (As(V)). This allowed for the determination of inorganic arsenic as a single species, i.e. As(V), by anion-exchange HPLC-ICP-MS. The completeness of the oxidation was verified by recovery of As(V) which was added to the samples as As(III) prior to the dissolution procedure. The full recovery of As(V) at 104 +/- 7% (n = 5) indicated good analytical accuracy. The uncertified inorganic arsenic content in the certified reference material TORT-2 was 0.186 +/- 0.014 ng g(-1) (n = 6). The method was employed for the determination of total arsenic and inorganic arsenic in 60 fish samples including salmon from fresh and saline waters and in plaice. The majority of the results for inorganic arsenic were lower than the LOD of 3 ng g(-1), which corresponded to less than one per thousand of the total arsenic content in the fish samples. For mackerel, however, the recovery of As(III) was incomplete and the method was not suited for this fat-rich fish.