Testing single extraction methods and in vitro tests to assess the geochemical reactivity and human bioaccessibility of silver in urban soils amended with silver nanoparticles

To assess if the geochemical reactivity and human bioaccessibility of silver nanoparticles (AgNPs) in soils can be determined by routine soil tests commonly applied to other metals in soil, colloidal Ag was introduced to five pots containing urban soils (equivalent to 6.8 mg Ag kg(-1) soil). Following a 45 days stabilization period, the geochemical reactivity was determined by extraction using 0.43 M and 2 M HNO3. The bioaccessibility of AgNPs was evaluated using the Simplified Bioaccessibility Extraction Test (SBET) the "Unified BARGE Method" (UBM), and two simulated lung fluids (modified Gamble's solution (MGS) and artificial lysosomal fluid (ALF)). The amount of Ag extracted by 0.43 M and 2 M HNO3 soil tests was <8% and <50%, respectively of the total amount of Ag added to soils suggesting that the reactivity of Ag present in the soil can be relatively low. The bioaccessibility of Ag as determined by the four in vitro tests ranged from 17% (ALF extraction) to 99% (SBET) indicating that almost all Ag can be released from soil due to specific interactions with the organic ligands present in the simulated body fluids. This study shows that to develop sound soil risk evaluations regarding soil contamination with AgNPs, aspects of Ag biochemistry need to be considered, particularly when linking commonly applied soil tests to human risk assessment.

Impairment of mitochondrial energy metabolism of two marine fish by in vitro mercuric chloride exposure

The goal of this work was to understand the extent of mercury toxic effects in liver metabolism under an episode of acute contamination. Hence, the effects of in vitro mercuric chloride in liver mitochondria were assessed in two commercial marine fish: Senegalese sole (Solea senegalensis) and gilthead seabream (Sparus aurata). Liver mitochondria were exposed to 0.2mgL(-1) of mercury, the average concentration found in fish inhabiting contaminated areas. Mercuric chloride depressed mitochondrial respiration state 3 and the maximal oxygen consumption in the presence of FCCP indicating inhibitory effects on the oxidative phosphorylation and on the electron transport chain, respectively. The inhibition of F1Fo-ATPase and succinate-dehydrogenase activities also corroborated the ability of mercury to inhibit ADP phosphorylation and the electron transport chain. This study brings new understanding on the mercury levels able to impair fish mitochondrial function, reinforcing the need for further assessing bioenergetics as a proxy for fish health status.

Field transplantation of the bivalve Scrobicularia plana along a mercury gradient in Ria de Aveiro (Portugal): uptake and depuration kinetics

The bioaccumulation and depuration capabilities of mercury by the edible bivalve Scrobicularia plana was studied in a coastal lagoon (Ria de Aveiro, Portugal) through a transplantation experiment. Little information on this topic is available in the literature, especially concerning different tissues' responses to contaminant exposure, but the present study is one of the few works that can surpass this knowledge gap. Organisms from a reference area were transplanted to two different contaminated areas in the Ria de Aveiro. In both areas, the bivalves (i.e., entire organism, digestive gland and the rest of the organism) presented a similar saturation model of mercury accumulation, the digestive gland being the tissue that reached the highest concentrations after 25 days of exposure to the contaminant. During this short uptake period, the transplanted organisms reached 20-30% of the concentrations observed in resident contaminated organisms. After the exposure period, the organisms were transplanted to a clean area for more than 25 days of depuration. At the end of the transplantation period, organisms lost approximately 50% of their mercury body burden (60%: the entire organism and digestive gland; 35%: gills and 40%: the rest of the organism) and the ones from the least contaminated site almost reached the concentrations recorded in the reference area. So, the results suggest that S. plana is a promising biomonitoring species, since it accumulates the contaminant in a considerable extent quite rapidly and at the same time it has a low metal retention capacity (low biological half-life) when exposed to clean sediments.

A de novo 10.79 Mb interstitial deletion at 2q13q14.2 involving PAX8 causing hypothyroidism and mullerian agenesis: a novel case report and literature review

Reports of interstitial deletions involving proximal long arm of chromosome 2 are limited. Based on early chromosomal analysis studies, the phenotypic consequence of deletions at the ancestral chromosome fusion site at chromosome 2q13q14.1 remains unclear. A recurrent 1.71 Mb deletion at 2q13 has recently been proposed as a new genomic disorder, associated with an increased risk of intellectual disability and craniofacial dysmorphism. Herein, we report the case of a 12 year-old girl with unique clinical features including global developmental delay, mullerian agenesis, and hypothyroidism associated with a normal size and position of the thyroid gland, as well as negative thyroid antibodies. Microarray-based comparative genomic hybridization study revealed a de novo 10.79 Mb deletion at 2q13q14.2 (111,548,932–122,336,492), which involves more than 88 UCSC genes, 38 of which are OMIM genes, 7 of which are disease-causing and 3 of which (including GLI2, IL1B and PAX8) show a dominant inheritance pattern.. Interestingly, PAX8 (chr2:113,973,574–114,036,498), a member of the paired-box gene family, is essential for the formation of thyroxine-producing follicular cells. Autosomal dominant transmission of congenital thyroid hypoplasia due to loss-of-function mutation of PAX8 suggests a possible haploinsufficiency effect. Additionally, PAX8 is also expressed in the tissue primordia that form both the mullerian duct derivatives and the upper urinary tracts. A recent study has associated a novel PAX8 mutation with a severe form of hypothyroidism and abnormalities in the urogenital tract. Taken together, the unique clinical manifestation seen in this patient could be attributed to the heterozygous deletion of PAX8 gene. A prospective investigation is merited to fully evaluate the pathogenic effect of the interstitial deletion of 2q13q14.2.

Oral bioaccessibility and human exposure to anthropogenic and geogenic mercury in urban, industrial and mining areas

The objective of this study was to characterize the link between bioaccessibility and fractionation of mercury (Hg) in soils and to provide insight into human exposure to Hg due to inhalation of airborne soil particles and hand-to-mouth ingestion of Hg-bearing soil. Mercury in soils from mining, urban and industrial areas was fractionated in organometallic forms; mobile; semi-mobile; and non-mobile forms as well as HCl-extractable Hg. The in vitro bioaccessibility of Hg was obtained by extracting soils with (1) a simulated human gastric fluid (pH1.5), and (2) a simulated human lung fluid (pH7.4). Total soil Hg concentrations ranged from 0.72 to 1.8 mg kg(-1) (urban areas), 0.28 to 94 mg kg(-1) (industrial area) and 0.92 to 37 mg kg(-1) (mining areas). Both organometallic Hg as well as 0.1M HCl extractable Hg were lower (<0.5% of total Hg) than Hg extracted by gastric fluid (up to 1.8% of total Hg) and lung fluid (up to 12% of total Hg). In addition, Hg extracted by lung fluid was significantly higher in urban and industrial soils (average 5.0-6.6% of total Hg) compared to mining soils. Such differences were related to levels of mobile Hg species in urban and industrial soils compared to mining soils. These results strengthen the need to measure site-specific Hg fractionation when determining Hg bioaccessibility. Results also show that ingestion and/or inhalation of Hg from soil particles can contribute up to 8% of adult total Hg intake when compared to total Hg intake via consumption of contaminated fish and animal products from contaminated areas.

Temporal characterization of mercury accumulation at different trophic levels and implications for metal biomagnification along a coastal food web

The main goal of this study was to assess temporal mercury variations along an estuarine food web to evaluate the mercury contamination level of the system and the risks that humans are exposed to, due to mercury biomagnification. The highest mercury concentrations in the sediments and primary producers (macrophytes) were observed during winter sampling. Instead, the highest mercury concentrations in the water, suspended particulate matter as well as in the zooplanktonic and suprabenthic communities were observed during summer sampling. Evidences of mercury biomagnification along the food web were corroborated by the positive biomagnification factors, particularly for omnivorous macrobenthic species. Comparing the mercury levels at distinct components with several environmental quality criteria it suggests that sediments, water and edible species (e.g., bivalve Scrobicularia plana and the crustacean Carcinus maenas) presented higher mercury levels than the values accepted by legislation which represent a matter of concern for the environment and human health.

Two biomarker-directed randomized trials in European and Chinese patients with nonsmall-cell lung cancer: the BRCA1-RAP80 Expression Customization (BREC) studies

BACKGROUND

In a Spanish Lung Cancer Group (SLCG) phase II trial, the combination of BRCA1 and receptor-associated protein 80 (RAP80) expression was significantly associated with outcome in Caucasian patients with nonsmall-cell lung cancer (NSCLC). The SLCG therefore undertook an industry-independent collaborative randomized phase III trial comparing nonselected cisplatin-based chemotherapy with therapy customized according to BRCA1/RAP80 expression. An analogous randomized phase II trial was carried out in China under the auspices of the SLCG to evaluate the effect of BRCA1/RAP80 expression in Asian patients.

PATIENTS AND METHODS

Eligibility criteria included stage IIIB-IV NSCLC and sufficient tumor specimen for molecular analysis. Randomization to the control or experimental arm was 1 : 1 in the SLCG trial and 1 : 3 in the Chinese trial. In both trials, patients in the control arm received docetaxel/cisplatin; in the experimental arm, patients with low RAP80 expression received gemcitabine/cisplatin, those with intermediate/high RAP80 expression and low/intermediate BRCA1 expression received docetaxel/cisplatin, and those with intermediate/high RAP80 expression and high BRCA1 expression received docetaxel alone. The primary end point was progression-free survival (PFS).

RESULTS

Two hundred and seventy-nine patients in the SLCG trial and 124 in the Chinese trial were assessable for PFS. PFS in the control and experimental arms in the SLCG trial was 5.49 and 4.38 months, respectively [log rank P = 0.07; hazard ratio (HR) 1.28; P = 0.03]. In the Chinese trial, PFS was 4.74 and 3.78 months, respectively (log rank P = 0.82; HR 0.95; P = 0.82).

CONCLUSION

Accrual was prematurely closed on the SLCG trial due to the absence of clinical benefit in the experimental over the control arm. However, the BREC studies provide proof of concept that an international, nonindustry, biomarker-directed trial is feasible. Thanks to the groundwork laid by these studies, we expect that ongoing further research on alternative biomarkers to elucidate DNA repair mechanisms will help define novel therapeutic approaches.

TRIAL REGISTRATION

NCT00617656/GECP-BREC and ChiCTR-TRC-12001860/BREC-CHINA.

Temperature behaviour of the yellow emission in GaN

Even in good quality undoped GaN samples, as assessed by the intense excitonic emission, the yellow band is present. This band has been attributed either to a shallow donor to deep double donor pair recombination [1], to a deep donor to a shallow acceptor [2] or to a shallow donor and a deep state [3]. However, its origin is not yet clear. We present data on time resolved spectroscopy compared with steady state results. These results indicate that there is no difference in band shape between steady state and time resolved spectra at all temperatures. However, in some samples there is an increase in intensity of the yellow band. It is concluded that besides a fast emission, due to prompt excitation of the centre, an indirect path from a trap 13.7 meV below the shallow donor is responsible for the long component of the decay and the intensity increase. An emission with a lifetime of ca. 300 ms is also present with a maximum at 2.35 eV.

Principles of thermal design with nematic liquid crystals

Highly engineered materials are arousing great interest because of their ability to manipulate heat, as described by the coordinate transformation approach. Based on recently developed analog gravity models, we present how a simple device based on nematic liquid crystals can achieve in principle either thermal concentration or expulsion. These outcomes are shown to stem from the topological properties of a disclination-like structure, induced in the nematic phase by anchoring conditions.

Cork stoppers as an effective sorbent for water treatment: the removal of mercury at environmentally relevant concentrations and conditions

The technical feasibility of using stopper-derived cork as an effective biosorbent towards bivalent mercury at environmentally relevant concentrations and conditions was evaluated in this study. Only 25 mg/L of cork powder was able to achieve 94 % of mercury removal for an initial mercury concentration of 500 μg/L. It was found that under the conditions tested, the efficiency of mercury removal expressed as equilibrium removal percentage does not depend on the amount of cork or its particle size, but is very sensitive to initial metal concentration, with higher removal efficiencies at higher initial concentrations. Ion exchange was identified as one of the mechanisms involved in the sorption of Hg onto cork in the absence of ionic competition. Under ionic competition, stopper-derived cork showed to be extremely effective and selective for mercury in binary mixtures, while in complex matrices like seawater, moderate inhibition of the sorption process was observed, attributed to a change in mercury speciation. The loadings achieved are similar to the majority of literature values found for other biosorbents and for other metals, suggesting that cork stoppers can be recycled as an effective biosorbent for water treatment. However, the most interesting result is that equilibrium data show a very rare behaviour, with the isotherm presenting an almost square convex shape to the concentration axis, with an infinite slope for an Hg concentration in solution around 25 μg/L.

Risk assessment for Cd, Cu, Pb and Zn in urban soils: chemical availability as the central concept

To assess the geochemical reactivity and oral bioaccessibility of Cd, Cu, Pb and Zn in urban soils from the Porto area, four extractions were performed including Aqua Regia (AR; pseudototal), 0.43 M HNO3 (reactive), 0.01 M CaCl2 (available), and 0.4 M glycine at pH = 1.5, SBET method (oral bioaccessible pool). Oral bioaccessibility in urban soils was higher than in samples from rural, industrial and mining areas which is most likely related to sources of metals and parent materials of corresponding soils. The availability and reactivity were described well by non-linear Freundlich-type equations when considering differences in soil properties. The resulting empirical models are able to predict availability and reactivity and can be used to improve the accuracy of risk assessment. Furthermore, a close 1:1 relationship exists between results from the 0.43 M HNO3 method and the SBET method which substantially facilitates risk assessment procedures and reduces analytical costs.

Mercury bioaccumulation and the population dynamics of Mesopodopsis slabberi (Crustacea: Mysidacea) along a mercury contamination gradient

The mercury bioaccumulation and population dynamics of the mysid Mesopodopsis slabberi was assessed along a mercury gradient in Ria de Aveiro (Portugal). M. slabberi is one of the most important mysid species in European temperate coastal shallow waters playing a key ecological role. Nevertheless, no references were found concerning the possible consequences of the Hg on the trophodynamics of these coastal ecosystems. M. slabberi showed a clear bioaccumulation along the Hg gradient and through life, with mature females reaching the highest concentrations. In terms of population structure, higher densities and biomasses of M. slabberi were assessed in the most contaminated areas contrarily to the least polluted areas. Despite the mercury accumulation in its tissues no strong negative effects on the structure and population dynamics of the species were observed. However, mysids might be important in the transfer of metals from the sediments and zooplankton to higher trophic levels such as fishes, most of them with commercial interest.

Risks associated with the transfer of toxic organo-metallic mercury from soils into the terrestrial feed chain

Although the transfer of organo-metallic mercury (OrgHg) in aquatic food webs has long been studied, it has only been recently recognized that there is also accumulation in terrestrial systems. There is still however little information about the exposure of grazing animals to OrgHg from soils and feed as well as on risks of exposure to animal and humans. In this study we collected 78 soil samples and 40 plant samples (Lolium perenne and Brassica juncea) from agricultural fields near a contaminated industrial area and evaluated the soil-to-plant transfer of Hg as well as subsequent trophic transfer. Inorganic Hg (IHg) concentrations ranged from 0.080 to 210mgkg(-1) d.w. in soils, from 0.010 to 84mgkg(-1) d.w. in roots and from 0.020 to 6.9mgkg(-1) d.w. in shoots. OrgHg concentrations in soils varied between 0.20 and 130μgkg(-1) d.w. representing on average 0.13% of the total Hg (THg). In root and shoot samples OrgHg comprised on average 0.58% (roots) and 0.66% (shoots) of THg. Average bioaccumulation factors (BAFs) for OrgHg in relation to soil concentrations were 3.3 (for roots) and 1.5 (for shoots). The daily intake (DI) of THg in 33 sampling sites exceeded the acceptable daily intake (ADI) of THg of both cows (ADI=1.4mgd(-1)) and sheep (ADI=0.28mgd(-1)), in view of food safety associated with THg in animal kidneys. Estimated DI of OrgHg for grazing animals were up to 220μgd(-1) (for cows) and up to 33μgd(-1) (for sheep). This study suggested that solely monitoring the levels of THg in soils and feed may not allow to adequately taking into account accumulation of OrgHg in feed crops and properly address risks associated with OrgHg exposure for animals and humans. Hence, the inclusion of limits for OrgHg in feed quality and food safety legislation is advised.

Core-shell magnetite-silica dithiocarbamate-derivatised particles achieve the Water Framework Directive quality criteria for mercury in surface waters

The sorption capacity of nanoporous titanosilicate Engelhard titanosilicate number 4 (ETS-4) and silica-coated magnetite particles derivatised with dithiocarbamate groups towards Hg(II) was evaluated and compared in spiked ultra-pure and spiked surface-river water, for different batch factors. In the former, and using a batch factor of 100 m(3)/kg and an initial Hg(II) concentrations matching the maximum allowed concentration in an effluent discharge, both materials achieve Hg(II) uptake efficiencies in excess of 99 % and a residual metal concentration lower than the guideline value for drinking water quality. For the surface-river water and the same initial concentration, the Hg(II) uptake efficiency of magnetite particles is outstanding, achieving the quality criteria established by the Water Framework Directive (concerning Hg concentration in surface waters) using a batch factor of 50 m(3)/kg, while the efficiency of ETS-4 is significantly inferior. The dissimilar sorbents' Hg(II) removal efficiency is attributed to different uptake mechanisms. This study also highlights the importance of assessing the effective capacity of the sorbents under realistic conditions in order to achieve trustable results.