Inhibitors of the inducible microsomal prostaglandin E2 synthase (mPGES-1) derived from MK-886

A series of potent and selective inhibitors of the inducible microsomal PGE2 synthase (mPGES-1) has been developed based on the indole FLAP inhibitor MK-886. Compounds 23 and 30 inhibit mPGES-1 with potencies in the low nanomolar range and with selectivities of at least 100-fold compared to their inhibition of mPGES-2, thromboxane synthase and binding affinity to FLAP. They also block the production of PGE2 in cell based assays but with a decreased potency and more limited selectivity compared to the enzyme assays.     

Evidence for genetic drift in the diversification of a geographically isolated population of the hyperthermophilic archaeon Pyrococcus

Genetic drift is a mechanism of population divergence that is important in the evolution of plants and animals but is thought to be rare in free-living microorganisms because of their typically large population sizes and unrestricted means of dispersal. We used both phylogenetic and insertion sequence (IS) element analyses in hyperthermophilic archaea of the genus Pyrococcus to test the hypothesis that genetic drift played an important role in the diversification of these microorganisms. Multilocus sequence typing of a collection of 36 isolates of Pyrococcus, from different hydrothermal systems in the Pacific Ocean and the Mediterranean Sea, revealed that Pyrococcus populations from different geographic locations are genetically differentiated. Analysis of IS elements in these isolates exposed their presence in all individuals of only one geographically isolated lineage, that of Vulcano Island in the Mediterranean Sea. Detailed sequence analysis of six selected IS elements in the Vulcano population showed that these elements cause deleterious genomic alterations, including inactivation of gene function. The high frequency of IS elements in the sampled population together with their observed harmful effects in the genome of Pyrococcus provide molecular evidence that the Vulcano Island population of Pyrococcus is geographically isolated and that those genetic mobile elements have been brought up to high frequency by genetic drift. Thus, genetic drift resulting from physical isolation should be considered as a factor influencing differentiation in prokaryotes.     

Sequence of the Escherichia coli O26 O antigen gene cluster and identification of O26 specific genes

Escherichia coli associated with outbreaks of gastroenteritis and hemolytic uremic syndrome include clones with O antigens O157 and O111. However, O26 has emerged as an O antigen present in pathogenic strains, particularly those implicated in cases of infantile gastroenteritis worldwide. The O26 O antigen gene cluster was sequenced. It was found to contain the genes expected for biosynthesis of nucleotide sugars L-rhamnose, N-acetyl-L-fucosamine and N-acetyl-glucosamine, as well genes for O unit flippase, O antigen polymerase and potential transferase genes. By polymerase chain reaction testing against representative strains for the 166 Escherichia coli O serogroups and some randomly selected Gram-negative bacteria, we identified three O antigen genes that are highly specific to O26. This work provides the basis for a sensitive test for the rapid detection of pathogenic clones with the O26 antigen, which has implications for public health, especially in the control of food-borne outbreaks.     

Protein degradation in the rumen of red clover forage at various stages of growth and conserved as silage or wrapped big bales

In order to study the extent to which rumen soluble nitrogen can contribute to the intestinal flow, a study was carried out to simultaneously assess the dynamics of protein disappearance from dacron bags placed in the rumen and the amount of various N products in the rumen fluid (total nitrogen (tN), ammonia nitrogen (NH3-N), non-ammonia nitrogen (NAN)). The measurements were carried out on 4 sheep fed successively various red clover forages. These forages included the initial growth of fresh red clover (50% bud, first flower, and full flower). In addition, one silage and one wrapped big bale at the first flower stage and two wrapped big bales (harvested at 51% and 71% dry matter) at the full flower stage were given. The effective degradability of nitrogen (DegN) for a fresh forage estimated from the nylon bag procedure did not vary (p > 0.05) with the vegetation stage (0.727 for the bud stage, 0.694 at the first flower, 0.706 at the full flower). The DegN of the silage was higher (p < 0.05; 0.735) and the DegN of the wrapped big bale was markedly lower (p < 0.05; 0.660), than the original fresh forage at the first flower. The DegN of the wrapped big bales made at 51 and 71% DM, respectively, were 0.625 and 0.604 against 0.706 for fresh forage at the full flower stage. The concentrations of tN and NAN in the rumen fluid were low, highest 1 h to 2 h after feeding, and then decreasing up to 7 h after feeding whatever the growth stage and conservation mode. A part of the solubilised nitrogen remained as protein 1 h after feeding for fresh red clover harvested at various growth stages, while minimal protein could be seen in the rumen fluid after the sheep were fed silage or wrapped big bales. The part of NAN escaping rumen degradation and transiting with the rumen fluid was between 7 and 13% of the nitrogen disappearing from the nylon bags (NAN/CP x DegN) placed in the rumen. There was only a small difference for forages at different stages of growth, or modes of conservation. This fraction was higher for wrapped big bales and particularly for the late stage forage (wrapped big bale, 71% DM, harvested at the full flower stage).     

Rafts promote assembly and atypical targeting of a nonenveloped virus, rotavirus, in Caco-2 cells

Rotavirus follows an atypical pathway to the apical membrane of intestinal cells that bypasses the Golgi. The involvement of rafts in this process was explored here. VP4 is the most peripheral protein of the triple-layered structure of this nonenveloped virus. High proportions of VP4 associated with rafts within the cell as early as 3 h postinfection. In the meantime a significant part of VP4 was targeted to the Triton X-100-resistant microdomains of the apical membrane, suggesting that this protein possesses an autonomous signal for its targeting. At a later stage the other structural rotavirus proteins were also found in rafts within the cells together with NSP4, a nonstructural protein required for the final stage of virus assembly. Rafts purified from infected cells were shown to contain infectious particles. Finally purified VP4 and mature virus were shown to interact with cholesterol- and sphingolipid-enriched model lipid membranes that changed their phase preference from inverted hexagonal to lamellar structures. Together these results indicate that a direct interaction of VP4 with rafts promotes assembly and atypical targeting of rotavirus in intestinal cells.     

Progressive Cognitive Deficit,Motor Impairment and Striatal Pathology in a Transgenic Huntington Disease Monkey Model from Infancy to Adulthood

One of the roadblocks to developing effective therapeutics for Huntington disease (HD) is the lack of animal models that develop progressive clinical traits comparable to those seen in patients. Here we report a longitudinal study that encompasses cognitive and motor assessment, and neuroimaging of a group of transgenic HD and control monkeys from infancy to adulthood. Along with progressive cognitive and motor impairment, neuroimaging revealed a progressive reduction in striatal volume. Magnetic resonance spectroscopy at 48 months of age revealed a decrease of N-acetylaspartate (NAA), further suggesting neuronal damage/loss in the striatum. Postmortem neuropathological analyses revealed significant neuronal loss in the striatum. Our results indicate that HD monkeys share similar disease patterns with HD patients, making them potentially suitable as a preclinical HD animal model.     

Multiscale Approach to the Determination of the Photoactive Yellow Protein Signaling State Ensemble

The nature of the optical cycle of photoactive yellow protein (PYP) makes its elucidation challenging for both experiment and theory. The long transition times render conventional simulation methods ineffective, and yet the short signaling-state lifetime makes experimental data difficult to obtain and interpret. Here, through an innovative combination of computational methods, a prediction and analysis of the biological signaling state of PYP is presented. Coarse-grained modeling and locally scaled diffusion map are first used to obtain a rough bird''s-eye view of the free energy landscape of photo-activated PYP. Then all-atom reconstruction, followed by an enhanced sampling scheme; diffusion map-directed-molecular dynamics are used to focus in on the signaling-state region of configuration space and obtain an ensemble of signaling state structures. To the best of our knowledge, this is the first time an all-atom reconstruction from a coarse grained model has been performed in a relatively unexplored region of molecular configuration space. We compare our signaling state prediction with previous computational and more recent experimental results, and the comparison is favorable, which validates the method presented. This approach provides additional insight to understand the PYP photo cycle, and can be applied to other systems for which more direct methods are impractical.     

Improved Planning Abilities in Binge Eating

Objective

The role of planning in binge eating episodes is unknown. We investigated the characteristics of planning associated with food cues in binging patients. We studied planning based on backward reasoning, reasoning that determines a sequence of actions back to front from the final outcome.

Method

A cross-sectional study was conducted with 20 healthy participants, 20 bulimia nervosa (BN), 22 restrictive (ANR) and 23 binging anorexia nervosa (ANB), without any concomitant impulsive disorder. In neutral/relaxing, binge food and stressful conditions, backward reasoning was assessed with the Race game, promotion of delayed large rewards with an intertemporal discounting task, attention with the Simon task, and repeating a dominant behavior with the Go/No-go task.

Results

BN and to a lower extent ANB patients succeeded more at the Race game in food than in neutral condition. This difference discriminated binging from non-binging participants. Backward reasoning in the food condition was associated with lower approach behavior toward food in BN patients, and higher food avoidance in ANB patients. Enhanced backward reasoning in the food condition related to preferences for delayed large rewards in BN patients. In BN and ANB patients the enhanced success rate at the Race game in the food condition was associated with higher attention paid to binge food.

Conclusion

These findings introduce a novel process underlying binges: planning based on backward reasoning is associated with binges. It likely aims to reduce craving for binge foods and extend binge refractory period in BN patients, and avoid binging in ANB patients. Shifts between these goals might explain shifts between eating disorder subtypes.     

Severe adult burn survivors. What information about skin allografts?

During the acute phase of a severe burn, surgery is an emergency. In this situation, human skin allografts constitute an effective temporary skin substitute. However, information about the use of human tissue can not be given to the patients because most of the allografted patients are unconscious due to their injury. This study explored the restitution of information on skin donation to patients who have been skin allografted and who have survived their injury. A qualitative study was conducted due to the limited number of patients in ability to be interviewed according to our medical and psychological criteria. 12 patients who had been treated between 2002 and 2008 were interviewed. Our results show that 10 of them ignored that they had received skin allografts. One of the two patients who knew that they had received allografts knew that skin had been harvested from deceased donor. All patients expressed that there is no information that should not be delivered. They also expressed their relief to have had the opportunity to discuss their case and at being informed during their interview. Their own experience impacted their view in favor of organ and tissue donation.