Fluidity and oxidative stress in erythrocytes from very low birth weight infants during their first 7 days of life

Objective: To study the evolution of lipid peroxidation, enzymatic antioxidants response, lipid profile and membrane fluidity in erythrocytes from very low birth weight (VLBW) infants during their first 7 days of extra-uterine life.

Study design: One hundred and twenty infants were selected and divided in two groups according to their weight and gestational age. Hydroperoxides, fatty-acid profile, fluidity (DPH and TMA-DPH) and catalase, SOD and GPx activities were measured in erythrocytes.

Results: VLBW group showed higher concentration of hydroperoxides and lower membrane fluidity during the first 72 h, lower SOD activity during the first 3 h and higher GPx activity during the first 7 days of life. Also, this group showed lower n-3 polyunsaturated fatty-acids percentage with respect to the term group.

Conclusion: Erythrocytes from VLBW infants showed higher oxidative damage and lower fluidity in their membranes, at least during the first 3 days of extra-uterine life, which may cause alterations in their functions and flexibility.     

The Effects of Foreknowledge and Task-Set Shifting as Mirrored in Cue- and Target-Locked Event-Related Potentials

The present study examined the use of foreknowledge in a task-cueing protocol while manipulating sensory updating and executive control in both, informatively and non-informatively pre-cued trials. Foreknowledge, sensory updating (cue switch effects) and task-switching were orthogonally manipulated in order to address the question of whether, and to which extent, the sensory processing of cue changes can partly or totally explain the final task switch costs. Participants responded faster when they could prepare for the upcoming task and if no task-set updating was necessary. Sensory cue switches influenced cue-locked ERPs only when they contained conceptual information about the upcoming task: frontal P2 amplitudes were modulated by task-relevant cue changes, mid-parietal P3 amplitudes by the anticipatory updating of stimulus-response mappings, and P3 peak latencies were modulated by task switching. Task preparation was advantageous for efficient stimulus-response re-mapping at target-onset as mirrored in target N2 amplitudes. However, N2 peak latencies indicate that this process is faster for all repeat trials. The results provide evidence to support a very fast detection of task-relevance in sensory (cue) changes and argue against the view of task repetition benefits as secondary to purely perceptual repetition priming. Advanced preparation may have a stronger influence on behavioral performance and target-locked brain activity than the local effect of repeating or switching the task-set in the current trial.     

Cystic Echinococcosis in the Province of álava,North Spain: The Monetary Burden of a Disease No Longer under Surveillance

Cystic echinococcosis (CE) is endemic in Spain but has been considered non-endemic in the province of Álava, Northern Spain, since 1997. However, Álava is surrounded by autonomous regions with some of the highest CE prevalence proportions in the nation, casting doubts about the current classification. The purpose of this study is to estimate the frequency of CE in humans and animals and to use this data to determine the societal cost incurred due to CE in the Álava population in 2005. We have identified epidemiological and clinical data from surveillance and hospital records, prevalence data in intermediate (sheep and cattle) host species from abattoir records, and economical data from national and regional official institutions. Direct costs (diagnosis, treatment, medical care in humans and condemnation of offal in livestock species) and indirect costs (productivity losses in humans and reduction in growth, fecundity and milk production in livestock) were modelled using the Latin hypercube method under five different scenarios reflecting different assumptions regarding the prevalence of asymptomatic cases and associated productivity losses in humans. A total of 13 human CE cases were reported in 2005. The median total cost (95% credible interval) of CE in humans and animals in Álava in 2005 was estimated to range between €61,864 (95%CI%: €47,304–€76,590) and €360,466 (95%CI: €76,424–€752,469), with human-associated losses ranging from 57% to 93% of the total losses, depending on the scenario used. Our data provide evidence that CE is still very well present in Álava and incurs important cost to the province every year. We expect this information to prove valuable for public health agencies and policy-makers, as it seems advisable to reinstate appropriate surveillance and monitoring systems and to implement effective control measures that avoid the spread and recrudescence of the disease.     

Increased sucrose level and altered nitrogen metabolism in Arabidopsis thaliana transgenic plants expressing antisense chloroplastic fructose-1,6-bisphosphatase

The pea chloroplastic fructose-1,6-bisphosphatase (FBPase) antisense construct reduced the endogenous level of expression of the corresponding Arabidopsis thaliana gene. The reduction of foliar FBPase activity in the transformants T(2) and T(3) generation ranged from 20% to 42%, and correlated with lower levels of FBPase protein. FBPase antisense plants displayed different phenotypes with a clear increase in leaf fresh weight. Measurements of photosynthesis revealed a higher carbon-assimilation rate. Decreased FBPase activity boosted the foliar carbohydrate contents, with a shift in the sucrose:starch ratio, which reached a maximum of 0.99 when the activity loss was 41%. Nitrate reductase activity decreased simultaneously with an increase in glutamine synthetase activity, which could be explained in terms of ammonium assimilation regulation by sugar content. These results suggest the role of FBPase as a key enzyme in CO(2) assimilation, and also in co-ordinating carbon and nitrogen metabolism.     

Sex-specific meiotic drive and selection at an imprinted locus

We present a one-locus model that breaks two symmetries of Mendelian genetics. Whereas symmetry of transmission is breached by allowing sex-specific segregation distortion, symmetry of expression is breached by allowing genomic imprinting. Simple conditions for the existence of at least one polymorphic stable equilibrium are provided. In general, population mean fitness is not maximized at polymorphic equilibria. However, mean fitness at a polymorphic equilibrium with segregation distortion may be higher than mean fitness at the corresponding equilibrium with Mendelian segregation if one (or both) of the heterozygote classes has higher fitness than both homozygote classes. In this case, mean fitness is maximized by complete, but opposite, drive in the two sexes. We undertook an extensive numerical analysis of the parameter space, finding, for the first time in this class of models, parameter sets yielding two stable polymorphic equilibria. Multiple equilibria exist both with and without genomic imprinting, although they occurred in a greater proportion of parameter sets with genomic imprinting.     

Crystal structure of a bacterial endospore coat component. A laccase with enhanced thermostability properties

Endospores produced by the Gram-positive soil bacterium Bacillus subtilis are shielded by a proteinaceous coat formed by over 30 structural components, which self-assemble into a lamellar inner coat and a thicker striated electrodense outer coat. The 65-kDa CotA protein is an abundant component of the outer coat layer. CotA is a highly thermostable laccase, assembly of which into the coat is required for spore resistance against hydrogen peroxide and UV light. Here, we report the structure of CotA at 1.7-A resolution, as determined by x-ray crystallography. This is the first structure of an endospore coat component, and also the first structure of a bacterial laccase. The overall fold of CotA comprises three cupredoxin-like domains and includes one mononuclear and one trinuclear copper center. This arrangement is similar to that of other multicopper oxidases and most similar to that of the copper tolerance protein CueO of Escherichia coli. However, the three cupredoxin domains in CotA are further linked by external interdomain loops, which increase the packing level of the structure. We propose that these interdomain loops contribute to the remarkable thermostability of the enzyme, but our results suggest that additional factors are likely to play a role. Comparisons with the structure of other monomeric multicopper oxidases containing four copper atoms suggest that CotA may accept the largest substrates of any known laccase. Moreover, and unlike other laccases, CotA appears to have a flexible lidlike region close to the substrate-binding site that may mediate substrate accessibility. The implications of these findings for the properties of CotA, its assembly and the properties of the bacterial spore coat structure are discussed.     

P2X4 Activation Modulates Volume-sensitive Outwardly Rectifying Chloride Channels in Rat Hepatoma Cells

Volume-sensitive outwardly rectifying (VSOR) Cl⁻ channels are critical for the regulatory volume decrease (RVD) response triggered upon cell swelling. Recent evidence indicates that H₂O₂ plays an essential role in the activation of these channels and that H₂O₂ per se activates the channels under isotonic isovolumic conditions. However, a significant difference in the time course for current onset between H₂O₂-induced and hypotonicity-mediated VSOR Cl⁻ activation is observed. In several cell types, cell swelling induced by hypotonic challenges triggers the release of ATP to the extracellular medium, which in turn, activates purinergic receptors and modulates cell volume regulation. In this study, we have addressed the effect of purinergic receptor activation on H₂O₂-induced and hypotonicity-mediated VSOR Cl⁻ current activation. Here we show that rat hepatoma cells (HTC) exposed to a 33% hypotonic solution responded by rapidly activating VSOR Cl⁻ current and releasing ATP to the extracellular medium. In contrast, cells exposed to 200 μm H₂O₂ VSOR Cl⁻ current onset was significantly slower, and ATP release was not detected. In cells exposed to either 11% hypotonicity or 200 μm H₂O₂, exogenous addition of ATP in the presence of extracellular Ca²⁺ resulted in a decrease in the half-time for VSOR Cl⁻ current onset. Conversely, in cells that overexpress a dominant-negative mutant of the ionotropic receptor P2X4 challenged with a 33% hypotonic solution, the half-time for VSOR Cl⁻ current onset was significantly slowed down. Our results indicate that, at high hypotonic imbalances, swelling-induced ATP release activates the purinergic receptor P2X4, which in turn modulates the time course of VSOR Cl⁻ current onset in a extracellular Ca²⁺-dependent manner.     

The Role of <Emphasis Type="SmallCaps">l</Emphasis>-arginine in Inclusion Complexes of Omeprazole with Cyclodextrins

In this study, we investigate how the effect of l-arginine (ARG) and cyclodextrins upon omeprazole (OME) stability and solubility. The effect of the presence of ARG on the apparent stability constants (K_1:1) of the inclusion complexes formed between OME and each cyclodextrin, β-cyclodextrin (βCD), and methyl-β-cyclodextrin (MβCD) is studied by phase solubility diagrams and nuclear magnetic resonance (NMR) spectroscopy. The interaction of OME with those cyclodextrins, in the presence of ARG, is characterized using NMR spectroscopy and molecular dynamics simulations. ARG significantly increases the drug solubility and complex stability, in comparison to inclusion complexes formed in its absence. The effect is more pronounced for the OME:βCD complex. ARG also contributes to a larger stability of OME when free in aqueous solution. The combination of ARG with cyclodextrins can represent an important tool to develop stable drug formulations.     

A novel histone exchange factor, protein phosphatase 2Cgamma, mediates the exchange and dephosphorylation of H2A-H2B

In eukaryotic nuclei, DNA is wrapped around a protein octamer composed of the core histones H2A, H2B, H3, and H4, forming nucleosomes as the fundamental units of chromatin. The modification and deposition of specific histone variants play key roles in chromatin function. In this study, we established an in vitro system based on permeabilized cells that allows the assembly and exchange of histones in situ. H2A and H2B, each tagged with green fluorescent protein (GFP), are incorporated into euchromatin by exchange independently of DNA replication, and H3.1-GFP is assembled into replicated chromatin, as found in living cells. By purifying the cellular factors that assist in the incorporation of H2A-H2B, we identified protein phosphatase (PP) 2C gamma subtype (PP2Cgamma/PPM1G) as a histone chaperone that binds to and dephosphorylates H2A-H2B. The disruption of PP2Cgamma in chicken DT40 cells increased the sensitivity to caffeine, a reagent that disturbs DNA replication and damage checkpoints, suggesting the involvement of PP2Cgamma-mediated histone dephosphorylation and exchange in damage response or checkpoint recovery in higher eukaryotes.