Structural characterization of the interactions of optimized product inhibitors with the N-terminal proteinase domain of the hepatitis C virus (HCV) NS3 protein by NMR and modelling studies

The interactions of peptide inhibitors, obtained by the optimization of N-terminal cleavage products of natural substrates, with the protease of human hepatitis C virus (HCV) are characterized by NMR and modelling studies. The S-binding region of the enzyme and the bound conformation of the ligands are experimentally determined. The NMR data are then used as the experimental basis for modelling studies of the structure of the complex. The S-binding region involves the loop connecting strands E2 and F2, and appears shallow and solvent-exposed. The ligand binds in an extended conformation, forming an antiparallel beta-sheet with strand E2 of the protein, with the P1 carboxylate group in the oxyanion hole.     

Effects of early dexamethasone therapy on pulmonary fibrogenic mediators and respiratory mechanics in preterm infants

Corticosteroid administration may prevent chronic lung disease in premature newborns, perhaps by modulating the synthesis of various cytokines, including those involved in fibrogenic processes. This study analyses the levels of three fibrogenic cytokines, namely vascular endothelial growth factor, transforming growth factor-beta 1 and basic fibroblast growth factor in tracheobronchial aspirate fluids collected from 20 premature newborns randomly assigned to the early dexamethasone group or to the control group. Furthermore, pulmonary function tests were performed on days 0 and 2 following the start of therapy. The results show that early corticosteroid administration reduces transforming growth factor-beta 1 and basic fibroblast growth factor levels, and abolishes the spontaneous vascular endothelial growth factor increase observed in untreated patients, concomitantly with significant improvement of dynamic lung compliance and shorter duration of the intubation period in the treated group of patients. Significant correlations were observed between the levels of transforming growth factor-beta 1 and vascular endothelial growth factor, indicating that the production of both these cytokines is coordinated. Finally, transforming growth factor-beta 1 ratios (day 2/day 0), representing early variations of the cytokine levels, were significantly different between treated and untreated subjects and correlated with the dynamic lung compliance ratios and the extubation day, suggesting that the downmodulation of some fibrogenic mediators may be involved in the mode of action of dexamethasone.     

Inhibition of PKCalpha induces a PKCdelta-dependent apoptotic program in salivary epithelial cells

We have used expression of a kinase dead mutant of PKCalpha (PKCalphaKD) to explore the role of this isoform in salivary epithelial cell apoptosis. Expression of PKCalphaKD by adenovirus-mediated transduction results in a dose-dependent induction of apoptosis in salivary epithelial cells as measured by the accumulation of sub-G1 DNA, activation of caspase-3, and cleavage of PKCdelta and PKCzeta, known caspase substrates. Induction of apoptosis is accompanied by nine-fold activation of c-Jun-N-terminal kinase, and an approximately two to three-fold increase in activated mitogen-activated protein kinase (MAPK) as well as total MAPK protein. Previous studies from our laboratory have shown that PKCdelta activity is essential for the apoptotic response of salivary epithelial cells to a variety of cell toxins. To explore the contribution of PKCdelta to PKCalphaKD-induced apoptosis, salivary epithelial cells were cotransduced with PKCalphaKD and PKCdeltaKD expression vectors. Inhibition of endogenous PKCdelta blocked the ability of PKCalphaKD to induce apoptosis as indicated by cell morphology, DNA fragmentation, and caspase-3 activation, indicating that PKCdelta activity is required for the apoptotic program induced under conditions where PKCalpha is inhibited. These findings indicate that PKCalpha functions as a survival factor in salivary epithelial cells, while PKCdelta functions to regulate entry into the apoptotic pathway.     

Unusual presentation of choriocarcinoma

Background  

Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain.     

Differential expression level of cytokeratin 8 in cells of the bovine nucleus pulposus complicates the search for specific intervertebral disc cell markers

Introduction  

Development of cell therapies for repairing the intervertebral disc is limited by the lack of a source of healthy human disc cells. Stem cells, particularly mesenchymal stem cells, are seen as a potential source but differentiation strategies are limited by the lack of specific markers that can distinguish disc cells from articular chondrocytes.     

GENSTAT programs for performing Muir's alternative partitioning of genotype-by-environment interaction

Genotype-by-environment (GE) interaction exists when different cultivars or strains have different phenotypic responses to environmental variation (Merila and Fry 1998). The phenomenon is of major concern in plant breeding, as it can limit gains in selecting superior cultivars. In animal breeding, the problem is also an important issue because breeding stocks are developed by a few companies but are used worldwide (Lin and Togashi 2002).     

The reversed binding of beta-phenethylamine inhibitors of DPP-IV: X-ray structures and properties of novel fragment and elaborated inhibitors

The co-crystal structure of beta-phenethylamine fragment inhibitor 5 bound to DPP-IV revealed that the phenyl ring occupied the proline pocket of the enzyme. This finding provided the basis for a general hypothesis of a reverse binding mode for beta-phenethylamine-based DPP-IV inhibitors. Novel inhibitor design concepts that obviate substrate-like structure-activity relationships (SAR) were thereby enabled, and novel, potent inhibitors were discovered.     

Prey state shapes the effects of temporal variation in predation risk

The ecological impacts of predation risk are influenced by how prey allocate foraging effort across periods of safety and danger. Foraging decisions depend on current danger, but also on the larger temporal, spatial or energetic context in which prey manage their risks of predation and starvation. Using a rocky intertidal food chain, we examined the responses of starved and fed prey (Nucella lapillus dogwhelks) to different temporal patterns of risk from predatory crabs (Carcinus maenas). Prey foraging activity declined during periods of danger, but as dangerous periods became longer, prey state altered the magnitude of risk effects on prey foraging and growth, with likely consequences for community structure (trait-mediated indirect effects on basal resources, Mytilus edulis mussels), prey fitness and trophic energy transfer. Because risk is inherently variable over time and space, our results suggest that non-consumptive predator effects may be most pronounced in productive systems where prey can build energy reserves during periods of safety and then burn these reserves as ‘trophic heat’ during extended periods of danger. Understanding the interaction between behavioural (energy gain) and physiological (energy use) responses to risk may illuminate the context dependency of trait-mediated trophic cascades and help explain variation in food chain length.     

Frequent Seizures Are Associated with a Network of Gray Matter Atrophy in Temporal Lobe Epilepsy with or without Hippocampal Sclerosis

Objective

Patients with temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) have diffuse subtle gray matter (GM) atrophy detectable by MRI quantification analyses. However, it is not clear whether the etiology and seizure frequency are associated with this atrophy. We aimed to evaluate the occurrence of GM atrophy and the influence of seizure frequency in patients with TLE and either normal MRI (TLE-NL) or MRI signs of HS (TLE-HS).

Methods

We evaluated a group of 172 consecutive patients with unilateral TLE-HS or TLE-NL as defined by hippocampal volumetry and signal quantification (122 TLE-HS and 50 TLE-NL) plus a group of 82 healthy individuals. Voxel-based morphometry was performed with VBM8/SPM8 in 3T MRIs. Patients with up to three complex partial seizures and no generalized tonic-clonic seizures in the previous year were considered to have infrequent seizures. Those who did not fulfill these criteria were considered to have frequent seizures.

Results

Patients with TLE-HS had more pronounced GM atrophy, including the ipsilateral mesial temporal structures, temporal lobe, bilateral thalami and pre/post-central gyri. Patients with TLE-NL had more subtle GM atrophy, including the ipsilateral orbitofrontal cortex, bilateral thalami and pre/post-central gyri. Both TLE-HS and TLE-NL showed increased GM volume in the contralateral pons. TLE-HS patients with frequent seizures had more pronounced GM atrophy in extra-temporal regions than TLE-HS with infrequent seizures. Patients with TLE-NL and infrequent seizures had no detectable GM atrophy. In both TLE-HS and TLE-NL, the duration of epilepsy correlated with GM atrophy in extra-hippocampal regions.

Conclusion

Although a diffuse network GM atrophy occurs in both TLE-HS and TLE-NL, this is strikingly more evident in TLE-HS and in patients with frequent seizures. These findings suggest that neocortical atrophy in TLE is related to the ongoing seizures and epilepsy duration, while thalamic atrophy is more probably related to the original epileptogenic process.