Dual Action of BPC194: A Membrane Active Peptide Killing Bacterial Cells

Membrane active peptides can perturb the lipid bilayer in several ways, such as poration and fusion of the target cell membrane, and thereby efficiently kill bacterial cells. We probe here the mechanistic basis of membrane poration and fusion caused by membrane-active, antimicrobial peptides. We show that the cyclic antimicrobial peptide, BPC194, inhibits growth of Gram-negative bacteria and ruptures the outer and inner membrane at the onset of killing, suggesting that not just poration is taking place at the cell envelope. To simplify the system and to better understand the mechanism of action, we performed Förster resonance energy transfer and cryogenic transmission electron microscopy studies in model membranes and show that the BPC194 causes fusion of vesicles. The fusogenic action is accompanied by leakage as probed by dual-color fluorescence burst analysis at a single liposome level. Atomistic molecular dynamics simulations reveal how the peptides are able to simultaneously perturb the membrane towards porated and fused states. We show that the cyclic antimicrobial peptides trigger both fusion and pore formation and that such large membrane perturbations have a similar mechanistic basis

Noradrenergic stimulation enhances human action monitoring

Noradrenergic neurotransmission has been associated with the modulation of higher cognitive functions mediated by the prefrontal cortex. In the present study, the impact of noradrenergic stimulation on the human action-monitoring system, as indexed by eventrelated brain potentials, was examined. After the administration of a placebo or the selective 2 -adrenoceptor antagonist yohimbine, which stimulates firing in the locus ceruleus and noradrenaline release, electroencephalograpic recordings were obtained from healthy volunteers performing a letter flanker task. Yohimbine led to an increase in the amplitude of the error-related negativity in conjunction with a significant reduction of action errors. Reaction times were unchanged, and the drug did not modify the N2 in congruent versus incongruent trials, a measure of preresponse conflict, or posterror adjustments as measured by posterror slowing of reaction time. The present findings suggest that the locus ceruleusnoradrenaline system exerts a rather specific effect on human action monitoring.

Nucleus accumbens is involved in human action monitoring: evidence from invasive electrophysiological recordings

The Nucleus accumbens (Nacc) has been proposed to act as a limbic-motor interface. Here, using invasive intraoperative recordings in an awake patient suffering from obsessive-compulsive disease (OCD), we demonstrate that its activity is modulated by the quality of performance of the subject in a choice reaction time task designed to tap action monitoring processes. Action monitoring, that is, error detection and correction, is thought to be supported by a system involving the dopaminergic midbrain, the basal ganglia, and the medial prefrontal cortex. In surface electrophysiological recordings, action monitoring is indexed by an error-related negativity (ERN) appearing time-locked to the erroneous responses and emanating from the medial frontal cortex. In preoperative scalp recordings the patient's ERN was found to be signifi cantly increased compared to a large (n = 83) normal sample, suggesting enhanced action monitoring processes. Intraoperatively, error-related modulations were obtained from the Nacc but not from a site 5 mm above. Importantly, crosscorrelation analysis showed that error-related activity in the Nacc preceded surface activity by 40 ms. We propose that the Nacc is involved in action monitoring, possibly by using error signals from the dopaminergic midbrain to adjust the relative impact of limbic and prefrontal inputs on frontal control systems in order to optimize goal-directed behavior.

Image Segmentation Using Information Bottleneck Method

In image processing, segmentation algorithms constitute one of the main focuses of research. In this paper, new image segmentation algorithms based on a hard version of the information bottleneck method are presented. The objective of this method is to extract a compact representation of a variable, considered the input, with minimal loss of mutual information with respect to another variable, considered the output. First, we introduce a split-and-merge algorithm based on the definition of an information channel between a set of regions (input) of the image and the intensity histogram bins (output). From this channel, the maximization of the mutual information gain is used to optimize the image partitioning. Then, the merging process of the regions obtained in the previous phase is carried out by minimizing the loss of mutual information. From the inversion of the above channel, we also present a new histogram clustering algorithm based on the minimization of the mutual information loss, where now the input variable represents the histogram bins and the output is given by the set of regions obtained from the above split-and-merge algorithm. Finally, we introduce two new clustering algorithms which show how the information bottleneck method can be applied to the registration channel obtained when two multimodal images are correctly aligned. Different experiments on 2-D and 3-D images show the behavior of the proposed algorithms

Analysis of Satellite Data for Forest Segmentation

In this work we study the classification of forest types using mathematics based image analysis on satellite data. We are interested in improving classification of forest segments when a combination of information from two or more different satellites is used. The experimental part is based on real satellite data originating from Canada. This thesis gives summary of the mathematics basics of the image analysis and supervised learning , methods that are used in the classification algorithm. Three data sets and four feature sets were investigated in this thesis. The considered feature sets were 1) histograms (quantiles) 2) variance 3) skewness and 4) kurtosis. Good overall performances were achieved when a combination of ASTERBAND and RADARSAT2 data sets was used.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/08/23 (A1,N32)-1918/08/29.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/01/18 (A1,N1)-1918/01/24.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/07/19 (A1,N26)-1918/07/25.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/09/06 (A1,N34)-1918/09/12.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/08/30 (A1,N33)-1918/09/05.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/04/12 (A1,N13)-1918/04/18.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/08/02 (A1,N29)-1918/08/08.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/03/22 (A1,N10)-1918/03/28.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/02/15 (A1,N5)-1918/02/22.

Le Droit des peuples : organe d'action socialiste nationale et internationale et de défense des réfugiés alsaciens, lorrains, belges, français

1918/10/25 (A1,N41)-1918/10/31.