Activation of Notch Signaling Is Required for Cholangiocarcinoma Progression and Is Enhanced by Inactivation of p53 In Vivo

Cholangiocacinoma (CC) is a cancer disease with rising incidence. Notch signaling has been shown to be deregulated in many cancers. However, the role of this signaling pathway in the carcinogenesis of CC is still not fully explored. In this study, we investigated the effects of Notch inhibition by γ-secretase inhibitor IX (GSI IX) in cultured human CC cell lines and we established a transgenic mouse model with liver specific expression of the intracellular domain of Notch (Notch-ICD) and inactivation of tumor suppressor p53. GSI IX treatment effectively impaired cell proliferation, migration, invasion, epithelial to mesenchymal transition and growth of softagar colonies. In vivo overexpression of Notch-ICD together with an inactivation of p53 significantly increased tumor burden and showed CC characteristics. Conclusion: Our study highlights the importance of Notch signaling in the tumorigenesis of CC and demonstrates that additional inactivation of p53 in vivo.     

Smokers with CT Detected Emphysema and No Airway Obstruction Have Decreased Plasma Levels of EGF,IL-15, IL-8 and IL-1ra

Rationale

Low-grade inflammation and emphysema have been shown to be associated with an increased risk of lung cancer. However, the systemic inflammatory response in patients with emphysema is still unknown.

Objective

To compare the plasma cytokine profiles in two groups of current or former smokers without airway obstruction: a control group of individuals without computed tomography (CT) detected emphysema vs. a study group of individuals with CT detected emphysema.

Methods

Subjects underwent a chest CT, spirometry, and determination of EGF, IL-15, IL-1ra, IL-8, MCP-1, MIP-1β, TGFα, TNFα, and VEGF levels in plasma. Cytokine levels in each group were compared adjusting for confounding factors.

Results

160 current smokers and former smokers without airway obstruction participated in the study: 80 without emphysema and 80 subjects with emphysema. Adjusted group comparisons revealed significant reductions in EGF (−0.317, p = 0.01), IL-15 (−0.21, p = 0.01), IL-8 (−0.180, p = 0.02) and IL-1ra (−0.220, p = 0.03) in subjects with emphysema and normal spirometry.

Conclusions

Current or former smokers expressing a well-defined disease characteristic such as emphysema, has a specific plasma cytokine profile. This includes a decrease of cytokines mainly implicated in activation of apoptosis or decrease of immunosurveillance. This information should be taken into account when evaluated patients with tobacco respiratory diseases.     

The Upper Palaeolithic site of Kalavan 1 (Armenia): An Epigravettian settlement in the Lesser Caucasus

The open-air site of Kalavan 1 is located in the Aregunyats mountain chain (at 1640 m above sea level) on the northern bank of Lake Sevan. It is the first Upper Palaeolithic site excavated in Armenia. Led by an Armenian-French team, several excavations (2005–2009) have revealed a well preserved palaeosoil, dated to around 14,000 BP (years before present), containing fauna, lithic artefacts, as well as several hearths and activity areas that structure the settlement. The initial studies enable placement of the site in its environment and justify palaeoethnological analysis of the Epigravettian human groups of the Lesser Caucasus.     

New Insights into the Assembly of Bacterial Secretins: STRUCTURAL STUDIES OF THE PERIPLASMIC DOMAIN OF XcpQ FROM PSEUDOMONAS AERUGINOSA*

The type II secretion system is a multiprotein assembly spanning the inner and outer membranes in Gram-negative bacteria. It is found in almost all pathogenic bacteria where it contributes to virulence, host tissue colonization, and infection. The exoproteins are secreted across the outer membrane via a large translocation channel, the secretin, which typically adopts a dodecameric structure. These secretin channels have large periplasmic N-terminal domains that reach out into the periplasm for communication with the inner membrane platform and with a pseudopilus structure that spans the periplasm. Here we report the crystal structure of the N-terminal periplasmic domain of the secretin XcpQ from Pseudomonas aeruginosa, revealing a two-lobe dimeric assembly featuring parallel subunits engaging in well defined interactions at the tips of each lobe. We have employed structure-based engineering of disulfide bridges and native mass spectrometry to show that the periplasmic domain of XcpQ dimerizes in a concentration-dependent manner. Validation of these insights in the context of cellular full-length XcpQ and further evaluation of the functionality of disulfide-linked XcpQ establishes that the basic oligomerization unit of XcpQ is a dimer. This is consistent with the notion that the dodecameric secretin assembles as a hexamer of dimers to ensure correct projection of the N-terminal domains into the periplasm. Therefore, our studies provide a key conceptual advancement in understanding the assembly principles and dynamic function of type II secretion system secretins and challenge recent studies reporting monomers as the basic subunit of the secretin oligomer.     

Mechanical double layer model for Saccharomyces Cerevisiae cell wall

The elastic modulus of the Baker’s yeast (Saccharomyces cerevisiae) cell wall reported in studies using atomic force microscopy (AFM) is two orders of magnitude lower than that obtained using whole cell compression by micromanipulation. Using finite element modelling, it is shown that Hertz-Sneddon analysis cannot be applied to AFM indentation data for single layer core–shell structures. In addition, the Reissner solution for shallow homogeneous spheres is not appropriate for thick walls such as those of yeast cells. In order to explain yeast compression measurements at different length scales, a double layer wall model is presented considering a soft external layer composed of mannoproteins, and a stiff inner layer of β-glucan fibres and chitin. Under this model, previous AFM studies using sharp indenters provide reasonable estimates of the external layer elastic modulus, while micromanipulation provides the total stiffness of the cell wall. Data from both measurements are combined to estimate the mechanical properties of the inner stiff layer.     

At the edge and on the top: molecular identification and ecology of Daphnia dentifera and D. longispina in high-altitude Asian lakes

The occurrence of members of the highly diverse Daphnia longispina complex in Southern and Central Asian high-mountain lakes has been recognized for more than a century. Until now, however, no molecular data have been available for these populations inhabiting the “Roof of the World.” Here, we present the first identification for D. gr. longispina from that region based on a molecular phylogeny. Our findings show that alpine lakes in the Pamir and Himalaya mountains host populations of widespread species of the complex, for which these are the highest known localities. A spineless morph from the Himalaya region, previously labeled as D. longispina var. aspina, was clustering tightly with D. dentifera, while a population from the Pamir mountain range was grouped with D. longispina. In addition, we analyzed ecological data available for lakes in the Khumbu region (Himalaya) to investigate ecological preferences of non-pigmented D. gr. longispina. The identified factors can at least partly be related to avoidance of high UV conditions by this species. We conclude that the widespread species D. dentifera and D. longispina also colonized the Asian high-mountain lakes, and identify the need for further research to trace the possible effect of rapid environmental changes in this region on the diversity and ecology of high-altitude Daphnia populations.     

Affinity chromatographic purification of human immunoglobulin a from chinese hamster ovary cell culture supernatant

Hexamer peptide ligand HWRGWV, initially screened from a solid phase combinatorial peptide library for immunoglobulins G (IgG) purification, is shown to also have potential for immunoglobulin A (IgA) purification. The determined dissociation constants for hIgA on HWRGWV resins at three different peptide densities from 0.11 to 0.55 meq/g fall in the range of 10^?6–10^?7 M, which are somewhat lower than those for hIgG. Although relatively low dynamic binding capacity (DBC) in the range of 9.2–16.8 mg IgA/mL resin at linear flow rates from 173 to 35 cm/h were obtained for IgA compared to IgG, the DBC value of HWRGWV for IgA is much greater than current commercially available affinity ligands. Although relatively lower binding affinity to secretory IgA compared to monomeric IgA was observed, the peptide ligand resins exhibit great potential for large‐scale purification of both human IgA and secretory IgA. Recoveries of 96.0% and 94.3%, and purities of 90.3% and 91.7% were achieved for human IgA and secretory IgA purification, respectively, from spiked Chinese hamster ovary cell culture supernatants without an extra afterwash step. Over 95% in purities were achieved for IgA and secretory IgA with an extra afterwash step; however, the recoveries would decrease at least 15% and 40% for IgA and secretory IgA, respectively. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013