Effects of ocean acidification on acid-base physiology, skeleton properties, and metal contamination in two echinoderms from vent sites in Deception Island, Antarctica.

Antarctic surface waters are expected to be the first to experience severe ocean acidification (OA) with carbonate undersaturation and large decreases in pH forecasted before the end of this century. Due to the long stability in environmental conditions and the relatively low daily and seasonal variations to which they are exposed, Antarctic marine organisms, especially those with a supposedly poor machinery to eliminate CO2 and protons and with a heavily calcified skeleton like echinoderms, are hypothesized as highly vulnerable to these environmental shifts. The opportunities offered by the natural pH gradient generated by vent activities in Deception Island caldera, Western Antarctic Peninsula, were used to investigate for the first time the acid-base physiologies, the impact of OA on the skeleton and the impact of pH on metal accumulation in the Antarctic sea star Odontaster validus and sea urchin Sterechinus neumayeri. The two species were sampled in four stations within the caldera, two at pH (total scale) 8.0-8.1 and two at reduced pH 7.8. Measured variables were pH, alkalinity, and dissolved inorganic carbon of the coelomic fluid; characteristic fracture force, stress and Young's modulus using Weibull statistics and Cd, Cu, Fe, Pb and Zn concentrations in the integument, gonads and digestive system. Recorded acid-base characteristics of both studied species fit in the general picture deduced from temperate and tropical sea stars and sea urchins but conditions and possibly confounding factors, principally food availability and quality, in the studied stations prevented definitive conclusions. Reduced seawater pH 7.8 and metals had almost no impact on the skeleton mechanical properties of the two investigated species despite very high Cd concentrations in O. validus integument. Reduced pH was correlated to increased contamination by most metals but this relation was weak. Translocation and caging experiments taking into account food parameters are proposed to better understand future processes linked to ocean acidification and metal contamination in Antarctic echinoderms.

Potential of polymethacrylate pseudo crown ethers as solid state polymer electrolytes.

The association of kinetic studies, DFT calculations and 1H-7Li NMR analyses allowed the control of the cyclo-ATRP of PEG9DMA and the production of polymethacrylate pseudo crown-ethers of various molar masses. Their potential to act as a solid-state polymer electrolyte in Li-ion batteries has been highlighted and may come from the supramolecular organization of the cyclo-PEG forming a Li+ diffusion channel.

The role of curvature in Diels-Alder functionalization of carbon-based materials.

We have estimated theoretically the impact of curvature on the free energies of activation and reaction associated with Diels-Alder reactions on carbon-based materials. Significant reduction is observed for both energy values with increasing curvature for core-functionalization, while the opposite trend prevails for edge-functionalization, as further supported by SEM/fluorescence measurements.

A review of the interest of sugammadex for deep neuromuscular blockade management in Belgium.

Oro-tracheal intubation and selected surgical conditions are facilitated by a deep neuromuscular block (NMB), but patient's security can be jeopardized by its residual effects at the time of tracheal extubation. Although neostigmine remains the reference reversal agent in many situations, the limitations of its efficacy must be well understood (ceiling effect, delay of action, side effects). It is best administered after re-emergence of the 3rd or 4th train-of-four (TOF) response. Sugammadex causes more predictable and more rapid recoveries from much deeper rocuronium-induced NMB. Therefore, maintaining deep NMB during surgery is no longer incompatible with rapid recovery and safe extubation. In Belgium, the use of sugammadex and its reimbursement depend on specific conditions. The excellent clinical tolerance of sugammadex benefits to patients at risk of developing complications related to residual NMB or to the undesirable effects of neostigmine. In all cases, neuromuscular transmission monitoring is the key to adequate NMB management.

Osteoconductive and bioresorbable composites based on poly(L,L-lactide) and pseudowollastonite: from synthesis and interfacial compatibilization to in vitro bioactivity and in vivo osseointegration studies.

This contribution reports on the elaboration of novel bioresorbable composites consisting of pseudowollastonite (psW) (a silicate-based polycrystalline ceramic (α-CaSiO(3))) and poly(L,L-lactide) as a valuable polymeric candidate in bone-guided regeneration. These composites were prepared by direct melt-blending to avoid the use of organic solvents harmful for biomedical applications. Amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymers synthesized by ring-opening polymerization were added to psW-based composites to modulate the bioactivity of the composites. The bioactivity of the composites was first evaluated by monitoring the release of bioactive Ca(2+) and (SiO(4))(4-) ions as well as the concomitant formation of hydroxyapatite on the material surface after soaking them in physiological fluid. Subsequently, the composites were studied in vitro to evaluate their cytotoxicity in the presence of SaOS-2 osteoblastic cells and in vivo to assess their osteoconductivity in an orthotopic rat tibia model. This study provides a first insight into the use of direct melt-blended psW-poly(L,L-lactide) composites for bone-regeneration applications.

Influence of the macromolecular architecture on the self-assembly of amphiphilic copolymers based on poly(N,N-dimethylamino-2-ethyl methacrylate) and poly(epsilon-caprolactone).

The self-assembly of amphiphilic copolymers consisting of poly( N, N-dimethylamino-2-ethyl methacrylate) (PDMAEMA) and poly(-caprolactone) (PCL) segments arranged in graft and linear diblock architectures was investigated in this work by means of dynamic light scattering (DLS) in aqueous solution and by atomic force microscopy (AFM) on thin deposits. The solid-state deposits of the micelles were generated by a "freeze-drying" technique that preserves the initial micelle morphology in solution. A comparison between the morphological properties of graft copolymers with corresponding diblock copolymers was established to demonstrate the effect of the copolymer architecture on the micelle structure and organization.

Miscibility in poly(L-lactide)-b-poly(epsilon-caprolactone) double crystalline diblock copolymers.

Thermally stimulated depolarization currents, TSDC, wide-angle X-ray scattering, WAXS, differential scanning calorimetry, DSC, and polarized light optical microscopy, PLOM, have been used to examine poly(L-lactide)-b-poly(epsilon-caprolactone) diblock copolymers in a wide composition range. Both components are crystallizable and the miscibility in the amorphous phase has been determined from the behavior of the primary relaxations which are the dielectric manifestation of the glass transition, and also from the superstructural morphology revealed by PLOM and the compositional dependence of the melting points as determined by DSC. Distinct segmental mobilities in the amorphous phase which can be well resolved by TSDC are present; the alpha mode of the slower component shifts to lower temperatures as the PCL content increases while the glass transition of neat PCL is present for all compositions. A relaxation times bimodal distribution is apparent for PCL-rich copolymers. The composition dependence of the multiple glass transitions detected in these weakly segregated copolymers are predicted by the self-concentration model for a miscible blend made of components with a large T(g) contrast.

Trace metal burdens and expression of heat stable low molecular mass proteins in the female asteroid Coscinasterias muricata--Fluctuations throughout the reproductive cycle.

Concentrations of the essential trace metals copper and zinc were measured in the pyloric caeca of female Coscinasterias muricata sampled from Port Phillip Bay, Victoria, Australia at monthly intervals for 15 months. Results indicate that the concentrations of these metals appear to be regulated by the reproductive cycle. Peaks in zinc concentration occurred simultaneously with peaks in progesterone concentration in the pyloric caeca. These findings suggest that zinc plays a role in gametogenesis and ovarian development. Fluctuations in pyloric caeca copper concentration appear inversely related to the pyloric caecal index and associated with oocyte diameter, indicative of a role for this metal in oogenesis. The levels of cytosolic heat stable low molecular mass (LMM) proteins were examined throughout the sampling period. Heat stable LMM proteins (metallothionein-like) of 12 kDa and 7.5 kDa (apparent molecular mass) and the concentrations of copper appear to be related; although the exact nature of these proteins remains unknown. No such relationship was observed between the levels of heat stable LMM proteins and zinc.

Long-lasting potentiation of a single-dose of rocuronium by amikacin: case report.

We report for the first time to our knowledge long-lasting (4 hours) potentiation of single intubating dose of rocuronium by a single bolus of amikacin given 55 minutes later in a woman having no precipitating factor (renal failure, hepatic failure, ionic disorder, other drugs influencing neuromuscular function). This patient had received the same rocuronium dose one month sooner in similar circumstances (without aminoglycoside antibiotic drug) and had not presented any prolonged neuromuscular blockade at this time. Neuromuscular blockade should be monitored in every patient receiving aminoglycoside antibiotic with even a single intubating dose of neuromuscular blocking drug.

Effect of crude oil contaminated sediment exposure on cytochrome P450 enzymes in the Australian asteroid Coscinasterias muricata.

Levels of cytochrome P450 enzymes were measured in pyloric caeca microsomes of the asteroid Coscinasterias muricata following exposure to sediment with nominal concentrations of 0, 0.1 or 2 ml crude oil kg(-1) (dry weight) and subsequent depuration. No significant differences were observed in total cytochrome P450 levels or cytochrome P418 levels following the exposure period. However after five days of depuration, levels of total P450 in the pyloric caeca of C. muricata exposed to the highest oiled sediment concentration were significantly lower than in specimens exposed to the other treatments. Cytochrome P418 levels were inversely related to total P450 levels following exposure and subsequent depuration. Preliminary results show that levels of CYP1A-like immunopositive protein (CYP1A-like IPP) in exposed asteroids exhibited a concentration response relationship following the exposure period. Variations in CYP1A-like IPP levels observed during the depuration period may be influenced by the sublethal toxicity of hydrocarbons within the crude oil.

Bioaccumulation and effects of PCBs and heavy metals in sea stars (Asterias rubens, L.) from the North Sea: a small scale perspective.

Sea stars (Asterias rubens L.) were collected in different stations distributed in the Southern Bight of the North Sea. Concentrations of four heavy metals and six PCB congeners were measured in two body compartments (body wall and pyloric caeca). In order to assess the potential harm of these contaminants, two biochemical parameters were measured in sea stars, viz. reactive oxygen species (ROS) production by amoebocytes and cytochrome P450 immunopositive protein (CYP1A IPP) induction in pyloric caeca. Sea stars from stations located in the plume of the Scheldt river showed the highest contamination levels. Other stations, similarly located, displayed lower levels. No simple relationship could be established between ROS production by sea star amoebocytes and contaminant levels measured in sea star tissues. CYP1A IPP induction displayed more contrasted responses, and highly significant regressions were found between PCB concentrations measured in pyloric caeca and CYP1A IPP. Both biological parameters were found to vary significantly over the study area. On the whole, data indicated that contamination levels and subsequent effects in sea stars were comparable to those described in previous large-scale studies, but that working at a smaller scale highlighted the existence of patterns of contamination which can blur general trends due to major contamination sources like contaminated rivers.

Levels and effects of PCDD/Fs and co-PCBs in sediments, mussels, and sea stars of the intertidal zone in the southern North Sea and the English Channel.

There is considerable concern regarding dioxin-like compounds (DLCs) in the marine environment. These ubiquitous contaminants are highly resistant to degradation, highly accumulated by marine organisms, and extremely toxic. Concentrations of DLCs, including 7 polychlorodibenzo-p-dioxins, 10 polychlorodibenzofurans, and 4 coplanar polychlorinated biphenyls, were determined in sediments, mussels (Mytilus edulis), and sea stars (Asterias rubens) from five intertidal stations distributed along the Belgian coast and the English Channel. The induction of a biomarker, cytochrome P450 immunopositive protein (CYP1A IPP), was also measured in sea star pyloric caeca. Although no significant differences were found between the considered stations, DLC levels were found to be relatively high in biota, especially when the toxicity of these compounds is considered. Particular concern arises from TEQ values determined in mussels from all locations. Sea stars were found to be more discriminant between the stations. CYP1A IPP induction was found to be significantly related to DLC levels measured in sea stars and allowed significant discrimination between the considered stations.

Installation of the hand influences acceleromyography measurement. A comparison with mechanomyography during neuromuscular recovery.

Acceleromyography is commonly used to monitor perioperative neuromuscular blockade and to prevent residual neuromuscular blockade at the time of tracheal extubation. However, there are problems associated with this method, such as obtaining stable values, particularly beneath the surgical fields. We compared TOF ratios obtained on both hands simultaneously using on one side mechanomyography and on the other acceleromyography, installed in four different ways: the hand simply lying on a board, fingers fixed with tape, use of the hand adaptor or the TOF-tube. Further to maintaining free thumb movement, the TOF-tube improves feasibility of acceleromyography by reducing the measurement variability while retaining accuracy.

Increased phagocytic activity in contaminated seastars (Asterias rubens) collected in the Southern Bight of the North Sea.

In invertebrates, the phagocytosis exerted by immune cells constitutes the main line of internal defence against offending microorganisms. This study assessed during two consecutive years the phagocytic activity in seastars (Asterias rubens) collected in stations along the Belgian and Dutch coasts. The contamination of these seastars by metals and PCBs were measured in parallel. Increased phagocytic activities were found in seastars collected in the plume of the Scheldt river. This correlated with the contamination of seastars by metals, mainly Pb, but not with the contamination by the analysed PCB congeners. Furthermore, the relationship between phagocytosis and metal contamination was reproducible from one year to another. The possible mechanisms explaining this effect are discussed in light of a direct or indirect link between phagocytic activity and metal contamination of seastars.

Alteration of cellular immune responses in the seastar Asterias rubens following dietary exposure to cadmium.

Several parameters of cellular immunity in seastars fed Cd-contaminated mussels were analyzed. The accumulation of cadmium in the seastars did not alter the concentration of amoebocytes in the coelomic fluid. On the contrary, the immune cells showed a reduced phagocytic activity and an increased production of reactive oxygen species. These effects may lead to an inability of the seastars to cope with bacterial infections and to oxidative damages to self tissue that could threaten the survival of the animals.

Measurement of EROD activity: caution on spectral properties of standards used.

The activity of the enzyme 7-ethoxy-resorufin- O-deethylase (EROD) has been extensively used in biomonitoring studies for more than a decade. Although the analytical procedure is simple, it is often poorly characterized. In this study spectral properties of particular standard compounds used to measure EROD activity (ethoxyresorufin and resorufin, standards from Molecular Probes) were tested in order to optimize excitation and emission wavelengths to be used in the fluorimetric assay of EROD activity. The optimal excitation wavelength for the detection of resorufin was 560 nm. At this wavelength the excitation represents only 37% of its maximum level for ethoxyresorufin, while it represents 86% for resorufin. This allows discrimination between the fluorescence emitted by both standards, favoring the formed resorufin. Our results demonstrate that any analytical work using spectrofluorometry to measure EROD activity should be preceded by precise determination of the spectral characteristics of each set of standards used.

Contaminant levels in sediments and asteroids (Asterias rubens L., Echinodermata) from the Belgian coast and Scheldt estuary: polychlorinated biphenyls and heavy metals.

The Southern Bight of the North Sea is particularly exposed to anthropogenic contamination, due to heavy urbanisation and industrialisation of its catchment area. The present work focuses on polychlorinated biphenyl (PCB) and metal contamination of the marine environment along and off the Belgian coast. Its objectives were to compare the concentrations of seven PCB congeners and four heavy metals in the sediments (a repository for anthropogenic contaminants) and in the asteroid Asterias rubens (a recognized bioindicator species). Nineteen sampling stations were considered between the mouth of the Scheldt Estuary and the southern limit of the Belgian coast (asteroids were found in 10 out of the 19 stations). PCB and metal concentrations measured in sediments and asteroids were in the range of values reported in previous studies. Stations under direct influence of the Scheldt were the most impacted by the considered contaminants. Metal concentrations varied according to the grain-size fraction considered. In asteroids, PCBs and metals were found to be selectively distributed among body compartments, and pyloric caeca were found to most efficiently discriminate between sampling stations contamination levels. PCB and metal analysis of sediments provided a physicochemical evaluation of the contamination, whereas analysis of asteroids introduced a biological dimension to the approach by taking into account bioavailability of the contaminants.

Supported nickel bromide catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate.

A new supported catalytic system, i.e. nickel bromide catalyst ligated by triphenylphosphine (TPP) ligands immobilized onto crosslinked polystyrene resins (PS-TPP) is reported. Per se, this catalyst does not allow any control over the polymerization of methyl methacrylate (MMA) initiated by ethyl 2-bromoisobutyrate but, in the presence of a given amount of purposely added free TPP, it promotes controlled ATRP of MMA. Indeed colorless PMMA chains of low polydispersity indices are readily recovered, the molecular weight of which linearly increases with monomer conversion and agrees with the expected values. Recycling of the supported catalyst is evidenced and does not prevent the polymerization from being controlled.

Environmental factors influencing the immune responses of the common European starfish (Asterias rubens).

The influence of handling, salinity, temperature, parasitism, and gender on the immune responses (reactive oxygen species (ROS) production and coelomic amoebocyte concentration (CAC) of the starfish Asterias rubens was investigated in experimental conditions. Additionally, a year-round monthly survey in two distant sites was conducted in order to understand which of these factors most influences the immunity of A. rubens in field conditions. All considered factors, except gender and handling stress, influenced the studied immune responses of A. rubens in experimental conditions. Amoebocyte ROS production was increased at low salinity and at the lowest temperature tested (6 degrees C). Amoebocyte concentration in the coelomic fluid was increased in starfish infested by the ciliate Orchitophrya stellarum. However, among all these factors, only temperature could be linked with the variability in ROS production measured in the field during the monthly survey. The variability in amoebocyte concentration in the field does not seem to be linked to any of the factors considered in this study; it appears to reflect mostly an inter-individual variation rather than seasonal fluctuations. Recommended periods and indicative values of immune responses are proposed for field studies using A. rubens.