Assessment of leachable elements in volcanic ashfall : a review and evaluation of a standardized protocol for ash hazard characterization.

Volcanic ash presents a widespread and common hazard during and after eruptions. Complex interactions between solid ash surfaces and volcanic gases lead to the formation of soluble salts that may be mobilized in aqueous environments. A variety of stakeholders may be concerned about the effects of ash on human and animal health, drinking water supplies, crops, soils and surface runoff. As part of the immediate emergency response, rapid dissemination of information regarding potentially hazardous concentrations of soluble species is critical. However, substantial variability in the methods used to characterize leachable elements makes it challenging to compare datasets and eruption impacts. To address these challenges, the International Volcanic Health Hazard Network (www.ivhhn.org) organized a two-day workshop to define appropriate methods for hazard assessment. The outcome of this workshop was a ‘consensus protocol’ for analysis of volcanic ash samples for rapid assessment of hazards from leachable elements, which was subsequently ratified by leading volcanological organizations. The purpose of this protocol is to recommend clear, standard and reliable methods applicable to a range of purposes during eruption response, such as assessing impacts on drinking-water supplies and ingestion hazards to livestock, and also applicable to research purposes. Where possible, it is intended that the methods make use of commonly available equipment and require little training. To evaluate method transferability, an interlaboratory comparison exercise was organized among six laboratories worldwide. Each laboratory received a split of pristine ash, and independently analyzed it according to the protocol for a wide range of elements. Collated results indicate good repeatability and reproducibility for most elements, thus indicating that the development of this protocol is a useful step towards providing standardized and reliable methods for ash hazard characterization. In this article, we review recent ash leachate studies, report the outcomes of the comparison exercise and present a revised and updated protocol based on the experiences and recommendations of the exercise participants. The adoption of standardized methods will improve and facilitate the comparability of results among studies and enable the ongoing development of a global database of leachate information relevant for informing volcanic health hazards assessment

Abrupt climate change at the MIS 5/4 transition recorded in a speleothem from the Eastern Mediterranean

The marine isotope stage (MIS) 5a to 4 transition (∼74 ka) was associated with rapid ice sheet expansion, declining moisture availability globally, and significant upheaval of terrestrial ecosystems across the northern hemisphere. Here, we present precisely dated speleothem trace element records spanning ∼90 to 70 ka from Dim Cave (Southern Türkiye) which provide crucial information regarding the climate response to this transition from the Eastern Mediterranean region. Trace element variability recorded in stalagmite DIM-E3 captures shifts in detrital influx, bedrock dissolution, and soil activity that collectively record two climatic signals: (1) high regional moisture availability between MIS 5c and 5b, and (2) increasingly arid conditions across the MIS 5a to MIS 4 transition. Both are contemporaneous with evidence for severe drying recorded across the Eastern Mediterranean and Middle East, as well as Asia, Europe, South America, and the North Atlantic. These results shed new light on the environmental consequences of rapid change in a climatologically sensitive region, and underscore the significance of atmospheric teleconnections in propagation of abrupt climate variability during the last glacial period

Proterozoic ophiolites and mafic-ultramafic complexes marginal to the Istanbul Block: An exotic terrane of Avalonian affinity in NW Turkey

Among the Proterozoic inliers in the Istanbul Block, the lowest structural levels are exposed in the Sunnice Massif, north of Bolu. Amphibolite-facies mafic and subordinate ultramafic rocks of the Cele meta-ophiolite underlie the greenschist-facies Ediacaran calc-alkaline Yellice metavolcanics, which are intruded by the similar to 565-576 Ma Dirgine granitoids. Homblende gneisses of the Cele meta-ophiolite comprise island arc metatholeiites and transitional to calc-alkaline metabasalts which, together with minor serpentinite are disposed in a broadly antiformal structure. The meta-ophiolitic rocks are therefore the oldest ophiolites in NW Turkey, and are themselves thrust on to a putative pre-existing continental margin, now represented by the metasedimentary migmatites of the Demirci gneisses, which may thus be the oldest rocks of the complex. The Istanbul Block is an exotic terrane. Unlike other western Turkish terranes, it lacks Variscan metamorphism: its different provenance, indicated by its geological record, faunal affinities, and inherited mid-Proterozoic isotopic dates, suggests a former link with Avalonian basement in England, NW Europe and the Maritime Provinces of Canada. Hence, together with other terranes now situated further east than the Avalonian terranes of NW Europe, the Istanbul Block may represent the easternmost extremities of Avalonia, which were detached during its end-Ordovician collision with the Bruno-Silesian Promontory on the SW margin of Baltica. Subsequent migration of the Istanbul Block to its present location occurred by eastward displacement by sinistral transpression along the southern margin of Baltica to a point east of the Dobrogea and south of the Scythian Platform, followed by collision with the Sakarya Block in the Mesozoic and Late Cretaceous southward displacement with the opening of the Black Sea basin

Compartmentalisation and groundwater‐surface water interactions in a prospective shale gas basin: Assessment using variance analysis and multivariate statistics on water quality data

An environmental concern with hydraulic fracturing for shale gas is the risk of groundwater and surface water contamination. Assessing this risk partly involves the identification and understanding of groundwater‐surface water interactions because potentially contaminating fluids could move from one water body to the other along hydraulic pathways. In this study we use water quality data from a prospective shale gas basin to determine: if surface water sampling could identify groundwater compartmentalisation by low‐permeability faults; and if surface waters interact with groundwater in underlying bedrock formations, thereby indicating hydraulic pathways. Variance analysis showed that bedrock geology was a significant factor influencing surface water quality, indicating regional‐scale groundwater‐surface water interactions despite the presence of an overlying region‐wide layer of superficial deposits averaging 30–40 m thickness. We propose that surface waters interact with a weathered bedrock layer through the complex distribution of glaciofluvial sands and gravels. Principal component analysis showed that surface water compositions were constrained within groundwater end‐member compositions. Surface water quality data showed no relationship with groundwater compartmentalisation known to be caused by a major basin fault. Therefore, there was no chemical evidence to suggest that deeper groundwater in this particular area of the prospective basin was reaching the surface in response to compartmentalisation. Consequently, in this case compartmentalisation does not appear to increase the risk of fracking‐related contaminants reaching surface waters, although this may differ under different hydrogeological scenarios

Substituted β-cyclodextrin and calix[4]arene as encapsulatory vehicles for platinum(II)-based DNA intercalators

The encapsulation of three platinum(II)-based anticancer complexes, [(5,6-dimethyl-1,10-phenanthroline)(1S,2Sdiaminocyclohexane) platinum(II)]2+ (56MESS), [(5,6-dimethyl-1,10-phenanthroline)(1R,2R-diaminocyclohexane)platinum( II)]2+ (56MERR), and [(5,6-dimethyl-1,10-phenanthroline)(ethylenediamine)platinum(II)]2+ (56MEEN), with carboxylated-β-cyclodextrin (c-β-CD) and p-sulfonatocalix[4]arene (s-CX[4]) has been examined by one- and twodimensional 1H nuclear magnetic resonance (NMR) spectroscopy, pulsed gradient spin-echo NMR, ultraviolet spectrophotometry, glutathione degradation experiments, and growth inhibition assays. Titration of any of the three metal complexes with c-β-CD resulted in 1:1 encapsulation complexes with the cyclodextrin located over the intercalating ligand of the metal complexes, with a binding constant of 104-105 M-1. In addition to binding over the phenanthroline ligand of 56MEEN, c-β-CD was also found to portal bind to the ethylenediamine ligand, with fast exchange kinetics on the NMR timescale between the two binding sites. In contrast, the three metal complexes all formed 2:2 inclusion complexes with s-CX[4] where the two metal complexes stacked in a head-to-tail configuration and were capped by the s-CX[4] molecules. Interestingly, the 56MEEN-s-CX[4] complex appeared to undergo a thermodynamically controlled rearrangement to a less soluble complex over time. Encapsulation of the metal complexes in either c-β-CD or s-CX[4] significantly decreased the metal complexes’ rate of diffusion, consistent with the formation of larger particle volumes. Encapsulation of 56MESS within s-CX[4] or c-β-CD protected the metal complex from degradation by reduced L-glutathione, with a reaction half-life greater than 9 days. In vitro growth inhibition assays using the LoVo human colorectal cancer cell line showed no significant change in the cytotoxicity of 56MESS when encapsulated by either s-CX[4] or c-β-CD

Substituted beta-cyclodextrin and calix[4]arene as encapsulatory vehicles for platinum(II)-based DNA intercalators

The encapsulation of three platinum(II)-based anticancer complexes, [(5,6-dimethyl-1,10-phenanthroline)(1S,2S-diaminocyclohexane)platinum(II)]2+ (56MESS), [(5,6-dimethyl-1,10-phenanthroline)(1R,2R-diaminocyclohexane)platinum(II)]2+ (56MERR), and [(5,6-dimethyl-1,10-phenanthroline)(ethylenediamine)platinum(II)]2+ (56MEEN), with carboxylated-β-cyclodextrin (c-β-CD) and p-sulfonatocalix[4]arene (s-CX[4]) has been examined by one- and two-dimensional 1H nuclear magnetic resonance (NMR) spectroscopy, pulsed gradient spin−echo NMR, ultraviolet spectrophotometry, glutathione degradation experiments, and growth inhibition assays. Titration of any of the three metal complexes with c-β-CD resulted in 1:1 encapsulation complexes with the cyclodextrin located over the intercalating ligand of the metal complexes, with a binding constant of 104−105 M−1. In addition to binding over the phenanthroline ligand of 56MEEN, c-β-CD was also found to portal bind to the ethylenediamine ligand, with fast exchange kinetics on the NMR timescale between the two binding sites. In contrast, the three metal complexes all formed 2:2 inclusion complexes with s-CX[4] where the two metal complexes stacked in a head-to-tail configuration and were capped by the s-CX[4] molecules. Interestingly, the 56MEEN-s-CX[4] complex appeared to undergo a thermodynamically controlled rearrangement to a less soluble complex over time. Encapsulation of the metal complexes in either c-β-CD or s-CX[4] significantly decreased the metal complexes' rate of diffusion, consistent with the formation of larger particle volumes. Encapsulation of 56MESS within s-CX[4] or c-β-CD protected the metal complex from degradation by reduced L-glutathione, with a reaction half-life greater than 9 days. In vitro growth inhibition assays using the LoVo human colorectal cancer cell line showed no significant change in the cytotoxicity of 56MESS when encapsulated by either s-CX[4] or c-β-CD

Cellular and molecular mechanisms for the synergistic cytotoxicity elicited by oxaliplatin and pemetrexed in colon cancer cell lines

Purpose: Oxaliplatin effect in the treatment of colorectal cancer is improved upon combination with thymidylate synthase (TS) inhibitors. Pemetrexed is polyglutamated by the folylpolyglutamate synthase (FPGS) and blocks folate metabolism and DNA synthesis by inhibiting TS, dihydrofolate reductase (DHFR) and glycinamide ribonucleotide formyltransferase (GARFT). The present study evaluates the pharmacological interaction between oxaliplatin and pemetrexed in colorectal cancer cells. Methods: Human HT29, WiDr, SW620 and LS174T cells were treated with oxaliplatin and pemetrexed. Drug interaction was studied using the combination index method, while cell cycle was investigated with flow cytometry. The effects of drugs on Akt phosphorylation and apoptosis were studied with ELISA and fluorescence microscopy, respectively. RT-PCR analysis was performed to assess whether drugs modulated the expression of pemetrexed targets and of genes involved in DNA repair (ERCC1 and ERCC2). Finally, platinum–DNA adduct levels were detected by ultra-sensitive multi-collector inductively coupled plasma mass spectrometry (ICP-MS). Results: A dose-dependent inhibition of cell growth was observed after drug exposure, while a synergistic interaction was detected preferentially with sequential combinations. Oxaliplatin enhanced cellular population in the S-phase. Drug combinations increased apoptotic indices with respect to single agents, and both drugs inhibited Akt phosphorylation. RT-PCR analysis showed a correlation between the FPGS/(TS × DHFR × GARFT) ratio and pemetrexed sensitivity, as well as a downregulation of ERCC1, ERCC2, TS, DHFR and GARFT after drug exposure. In addition, pretreatment with pemetrexed resulted in an increase of oxaliplatin–DNA adducts. Conclusion: These data demonstrate that oxaliplatin and pemetrexed synergistically interact against colon cancer cells, through modulation of cell cycle, inhibition of Akt phosphorylation, induction of apoptosis and modulation of gene expression

The kinase inhibitor O(6)-cyclohexylmethylguanine (NU2058) potentiates the cytotoxicity of cisplatin by mechanisms that are independent of its effect upon CDK2.

International audience-Cyclohexylmethylguanine (NU2058) was developed as an inhibitor of CDK2 and was previously shown to potentiate cisplatin cytotoxicity . The aim of this study was to investigate the mechanism of cisplatin potentiation by NU2058