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Summary Past climatic fluctuations have played a major role in shaping the current plant biodiversity. Although harbouring an exceptional biota, oceanic islands have received little attention in studies on species demographic history and past vegetation patterns. We investigated the impact of past climatic changes on the effective population size of a tree (Coffea mauritiana) that is endemic to Reunion Island, located in the south‐western Indian Ocean (SWIO). Demographic changes were inferred using summary statistics calculated from genomic data. Using ecological niche modelling and the current distribution of genetic diversity, the paleodistribution of the species was also assessed. A reduction in the effective population size of C. mauritiana during the last glaciation maximum was inferred. The distribution of the species was reduced on the western side of the island, due to low rainfall. It appeared that a major reduction in rainfall and a slight temperature decrease prevailed in the SWIO. Our findings indicated that analyses on the current patterns of intraspecific genetic variations can efficiently contribute to past climatic changes characterisation in remote islands. Identifying area with higher resilience in oceanic islands could provide guidance in forest management and conservation faced to the global climate change.

To report the clinical efficiency and complications in patients treated with retrograde transvenous ethanol embolization of high-flow peripheral arteriovenous malformations (AVMs). Retrograde transvenous ethanol embolization of high-flow AVMs is a technique that can be used to treat AVMs with a dominant outflow vein whenever conventional interventional procedures have proved insufficient.This is a retrospective study of the clinical effectiveness and complications of retrograde embolization in five patients who had previously undergone multiple arterial embolization procedures without clinical success.Clinical outcomes were good in all patients but were achieved at the cost of serious, although transient, complications in three patients.Retrograde transvenous ethanol embolization is a highly effective therapy for high-flow AVMs. However, because of the high complication rate, it should be reserved as a last resort, to be used after conventional treatment options have failed.

AbstractA new approach for the replacement of heart valves consists of obtaining an acellular matrix from animal aortic valves that performs mechanically, is nonantigenic, and is free from calcification and fibroblast proliferation. Novel biochemical treatments must be developed for this purpose. In this work, we focus on the characterization of collagen in acellular bovine cardiovascular tissues, fresh or glutaraldehyde treated, and stored in different solutions [phosphate‐buffered saline (PBS), ethanol, octanol, and glutaraldehyde], to determine whether the resulting fibrous material is structurally preserved. The preservation of the triple helical structure of collagen is checked by differential scanning calorimetry (DSC), which is a well suited technique to analyze thermal transitions in proteins, such as denaturation. To get insight into the molecular dynamics of collagen in the nanometric range, we used thermally stimulated currents, a dielectric technique running at low frequency, that measure the dipolar reorientations in proteins submitted to a static electrical field. The combined use of these two techniques allowed us to evaluate the physical structure and conformation of collagen after the different chemical treatments. We have found that the glutaraldehyde treatment followed by octanol storage preserves the triple helical conformation of the polypeptidic chains of collagen, contrary to the ethanol and PBS storage that induce drastic changes in the thermal and dielectric behavior of the protein. Moreover, this particular chemical treatment stabilizes the collagen structure (shift toward high temperature of the collagen denaturation and stiffening of the chains by a cross‐linking action) when compared to the control sample, and so could provide interesting fibrous material for the conception of bioprosthetic heart valve. © 2002 Wiley Periodicals, Inc., J Biomed Mater Res 64A: 330–338, 2003

The fast decay in PEM fuel cells of a highly active, high performance, but unstable Fe/N/C catalyst like our NC_Ar + NH3 follows a chemical, not an electrochemical, demetallation mechanism for its ORR active FeN4 sites in the catalyst micropores.

In the present study, Tween 80, a non-ionic surfactant, has been used for enhanced hydrogen production by crude glycerol bioconversion using co-culture of Enterobacter aerogenes and Clostridium butyricum. The purpose of introducing the surfactant was to decrease the crude glycerol viscosity, so that apparent solubility and bioavailability of glycerol could be improved at the expenses of pretreatment steps. Experiments were planned using central composite design (CCD); crude glycerol and Tween 80 concentrations were optimized whereas, hydrogen production, glycerol utilization and viscosity of the media were considered as responses. The response surface for quadratic model showed, Tween 80 concentration had significant effect (p < 0.05) on all the three responses. Using the optimized conditions at 17.5 g/L crude glycerol and 15 mg/L Tween 80, hydrogen production reached a maximum of 32.1 ± 0.03 mmol/L of medium. The increase in hydrogen production was around 1.25-fold in presence of Tween 80 in comparison to its absence with 25.56 ± 0.91 mmol/L production. Selected optimum conditions were also validated against absence of crude glycerol (4.69 ± 0.76), with pretreated crude glycerol (20.06 ± 0.51) and across mono-culture system (15.43 ± 0.79 to 22.14 ± 0.94). Introduction of Tween 80 to the fermentation medium improved the glycerol utilization rate, resulting in increased hydrogen production and eliminated pretreatment steps.

We have characterized the general properties of the heat shock response of the Gram-positive hardy bacterium Enterococcus faecalis. The heat resistance (60 degrees C or 62.5 degrees C, 30 min) of log phase cells of E. faecalis grown at 37 degrees C was enhanced by exposing cells to a prior heat shock at 45 degrees C or 50 degrees C for 30 min. These conditioning temperatures also induced ethanol (22%, v/v) tolerance. The onset of thermotolerance was accompanied by the synthesis of a number of heat shock proteins. The most prominent bands had molecular weights in the range of 48 to 94kDa. By Western blot analysis two of them were found to be immunologically related to the well known DnaK (72kDa) and GroEL (63kDa) heat shock proteins of Escherichia coli. Four other proteins showing little or no variations after exposure to heat are related to DnaJ, GrpE and Lon (La) E. coli proteins and to the Bacillus subtilis sigma 43 factor. Ethanol (2% or 4%, v/v) treatments elicited a similar response although there was a weaker induction of heat shock proteins than with heat shock.

AbstractActivation of potassium (K+) currents plays a critical role in the control of programmed cell death. Because pituitary adenylate cyclase‐activating polypeptide (PACAP) has been shown to inhibit the apoptotic cascade in the cerebellar cortex during development, we have investigated the effect of PACAP on K+ currents in cultured cerebellar granule cells using the patch‐clamp technique in the whole‐cell configuration. Two types of outward K+ currents, a transient K+ current (IA) and a delayed rectifier K+ current (IK) were characterized using two different voltage protocols and specific inhibitors of K+ channels. Application of PACAP induced a reversible reduction of the IK amplitude, but did not affect IA, while the PACAP‐related peptide vasoactive intestinal polypeptide had no effect on either types of K+ currents. Repeated applications of PACAP induced gradual attenuation of the electrophysiological response. In the presence of guanosine 5′‐[γthio]triphosphate (GTPγS), PACAP provoked a marked and irreversible IK depression, whereas cell dialysis with guanosine 5′‐[βthio]diphosphate GDPβS totally abolished the effect of PACAP. Pre‐treatment of the cells with pertussis toxin did not modify the effect of PACAP on IK. In contrast, cholera toxin suppressed the PACAP‐induced inhibition of IK. Exposure of granule cells to dibutyryl cyclic adenosine monophosphate (dbcAMP) mimicked the inhibitory effect of PACAP on IK. Addition of the specific protein kinase A inhibitor H89 in the patch pipette solution prevented the reduction of IK induced by both PACAP and dbcAMP. PACAP provoked a sustained increase of the resting membrane potential in cerebellar granule cells cultured either in high or low KCl‐containing medium, and this long‐term depolarizing effect of PACAP was mimicked by the IK specific blocker tetraethylammonium chloride (TEA). In addition, pre‐incubation of granule cells with TEA suppressed the effect of PACAP on resting membrane potential. TEA mimicked the neuroprotective effect of PACAP against ethanol‐induced apoptotic cell death, and the increase of caspase‐3 activity observed after exposure of granule cells to ethanol was also significantly inhibited by TEA. Taken together, the present results demonstrate that, in rat cerebellar granule cells, PACAP reduces the delayed outward rectifier K+ current by activating a type 1 PACAP (PAC1) receptor coupled to the adenylyl cyclase/protein kinase A pathway through a cholera toxin‐sensitive Gs protein. Our data also show that PACAP and TEA induce long‐term depolarization of the resting membrane potential, promote cell survival and inhibit caspase‐3 activity, suggesting that PACAP‐evoked inhibition of IK contributes to the anti‐apoptotic effect of the peptide on cerebellar granule cells.

Many problems concerned with the production and the purification of recombinant proteins must be addressed prior to launching an industrial production process. Among these problems, attention is focused on low-level expression that complicates the purification step and can jeopardise the process. The expression of a membrane protein, rP30, of Toxoplasma gondii in the yeast Schizosaccharomyces pombe led to a secretion of only 0.5 microg ml(-1). In order to obtain a sufficient quantity for biochemical characterization and evaluation in vitro diagnostic test development, strategies for both production and purification had to be optimized. First, the influence of four nitrogen sources (three peptones and yeast extract) on the growth rate, but also on the separation between the protein and the components of the fermentation broth was assessed. Second, batch and fed-batch fermentations were compared in terms of final biomass and rP30 concentrations. Third, three different protocols that included fixed and expanded bed ion exchange chromatography were compared for processing a large volume of feedstock. By using the most appropriate strategies, i.e. fed-batch fermentation, capture on EBA cation exchanger and affinity chromatography polishing, a purification factor of 1778 and a yield of 49% were achieved. These performances allowed a 12.5-fold increase for the overall rP30 process productivity.