Functional dissection of the "Drosophila melanogaster" fibroblast growth factor signalling pathway in branching morphogenesis of the developing tracheal system

Fibroblast Growth Factor (FGF) signalling is involved in numerous developmental processes ranging from cell determination to mitogenesis, and cell survival to cell migration. Interestingly, the same signalling pathway is used reiteratively throughout development and the question regarding the intracellular specificity is raised. Little is known about the intracellular signalling events of the FGF signalling pathway leading to specific cellular responses. Since the FGF signal is essential throughout embryonic and adult development and plays a role in many pathogenical processes, it is important to identify the factors, which determine the differential responses. We were interested to investigate the specificity of FGF signalling in a developmental context in which the signal induces directed cell migration, a cellular phenomenon that relies on changes of the cytoskeletal architecture. During gastrulation in early embryonic development, but also during the formation of organs in mammals and in Drosophila, FGFs have been shown to act as chemoattractants and guide cells toward their targets. In these contexts, FGF signalling has been shown to induce filopodia, which are long cellular extensions containing parallel actin bundles. Using Drosophila tracheal and mesodermal cell migration as model systems, we found that the intracellular domain of the two Drosophila FGF receptors (FGFRs) Breathless (Btl) and Heartless (Htl) can be replaced by the equivalent domains of Torso and EGFR, and yet these hybrid receptors will rescue cell migration in btl or htl mutant embryos, respectively. These chimeric receptors rescued cell migration even in the absence of Downstream-of-FGFR (Dof), a scaffolding protein that has been shown to be essential for FGF signalling in Drosophila. Thus, Dof acts specifically in the FGF signalling pathway. The functional characterization of Dof has demonstrated that Dof is indeed a FGFR specific phosphotarget and forms a complex with both FGFRs, but it is not a substrate of Torso. We performed a functional deletion analysis of the Btl receptor to define the interaction domains of Dof and other putative adapter proteins essential in the process of cell migration. Deletion of all putative interaction domains outside of the kinase domain did not affect the rescue capacity of the truncated Btl receptors in vivo suggesting that the kinase domain is sufficient for transmitting the signal. In line with this interpretation, results from S2 cell culture experiments revealed that Dof interacts with the kinase domain, and it does so independently of the activation state of the receptor. Surprisingly, in S2 cells, Btl receptors lacking the C-terminus did not auto-phosphorylate, as consequence we could not observe phosphorylation of Dof. We assume, that the short C-terminus is required for conformational changes of the kinase activation loop upon dimerization of the receptors to enable trans-phosphorylation. Dof belongs to a distinct family of adapter proteins than its functional homologue, the vertebrate FGFR adapter protein FRS2 that has been shown to constitutively interact with the juxtamembrane domain of the FGFRs. We could show that the human FGFR2, when expressed in the tracheal system, is only able to rescue cell migration defects effectively in the presence of Dof. These results suggest that Dof is able to interact with human FGFRs. At present, there is no evidence for a FRS2 homologue in Drosophila that might act as substitute for Dof. Upon receptor activation, Dof recruits the phosphatase Corkscrew (Csw), the Drosophila Shp2 homologue. Csw recruitment represents an essential step in FGF induced cell migration and transcriptional activation via the Ras/MAPK cascade. However, our results indicate that the activation of Ras is not sufficient to activate the migration machinery in tracheal and mesodermal cells. Ectopic activation of the Ras/MAPK cascade partially rescued tracheal cell migration in btl or dof mutant embryos. But high levels of sustained activation of Ras or the MAPK in wild-type tracheal cells did not disturb the migratory behaviour of the cells in contrast to ectopic activation of Branchless (Bnl), the Drosophila FGF homologue, which completely impaired primary branch outgrowth. In a wild-type tracheal system, MAPK activity is restricted to the tracheal tip cells. Single cell rescue experiments indicate that Bnl induces the migratory response exclusively in the tip cells of the outgrowing tracheal branches; the stalk cells are pulled forward by cell-cell adhesion contacts. The small GTPases of the Rho family have been shown to regulate cytoskeletal rearrangements. For tracheal development, Dcdc42 could function in collaboration with Drac in the regulation of actin dynamics according to our experiments. Additional proteins linking either Dof or Csw to the small GTPases have to be identified

Electrochemical reduction of indigo in fixed and fluidized beds of graphite granules

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled and lead to problematic waste products. The electrochemical reduction of indigo on a fixed bed cathode consisting of graphite granules has been investigated by spectrophotometric experiments in laboratory cells. Experiments yield information about the kinetics and show the possibility of this process for production of water soluble leuco indigo, which offers environmental benefits. The influence of noble metals deposited on the granules and of different pretreatment methods of the graphite is demonstrated. In addition, the immobilization of quinoid molecules on the graphite surface has been investigate

Direct electrochemical reduction of indigo: process optimization and scale-up in a flow cell

Reducing agents required in the dyeing process for vat and sulfur dyes cannot be recycled, and lead to problematic waste products. Therefore, modern economical and ecological requirements are not fulfilled. The industrial feasibility of the direct electrochemical reduction of indigo as a novel method has been determined and a preliminary optimization of electrolytic conditions was performed using a laboratory-scale flow-cell system. The role of current density, pH, temperature and the rate of mass transport are discussed. The influence of particle size reduction by the application of ultrasound is critically considere

Clinical consequences of switching from olanzapine to risperidone and vice versa in outpatients with schizophrenia: 36-month results from the worldwide schizophrenia outpatients health outcomes (W-SOHO) study

BACKGROUND: With many atypical antipsychotics now available in the market, it has become a common clinical practice to switch between atypical agents as a means of achieving the best clinical outcomes. This study aimed to examine the impact of switching from olanzapine to risperidone and vice versa on clinical status and tolerability outcomes in outpatients with schizophrenia in a naturalistic setting. METHODS: W-SOHO was a 3-year observational study that involved over 17,000 outpatients with schizophrenia from 37 countries worldwide. The present post hoc study focused on the subgroup of patients who started taking olanzapine at baseline and subsequently made the first switch to risperidone (n=162) and vice versa (n=136). Clinical status was assessed at the visit when the first switch was made (i.e. before switching) and after switching. Logistic regression models examined the impact of medication switch on tolerability outcomes, and linear regression models assessed the association between medication switch and change in the Clinical Global Impression-Schizophrenia (CGI-SCH) overall score or change in weight. In addition, Kaplan-Meier survival curves and Cox-proportional hazards models were used to analyze the time to medication switch as well as time to relapse (symptom worsening as assessed by the CGI-SCH scale or hospitalization). RESULTS: 48% and 39% of patients switching to olanzapine and risperidone, respectively, remained on the medication without further switches (p=0.019). Patients switching to olanzapine were significantly less likely to experience relapse (hazard ratio: 3.43, 95% CI: 1.43, 8.26), extrapyramidal symptoms (odds ratio [OR]: 4.02, 95% CI: 1.49, 10.89) and amenorrhea/galactorrhea (OR: 8.99, 95% CI: 2.30, 35.13). No significant difference in weight change was, however, found between the two groups. While the CGI-SCH overall score improved in both groups after switching, there was a significantly greater change in those who switched to olanzapine (difference of 0.29 points, p=0.013). CONCLUSION: Our study showed that patients who switched from risperidone to olanzapine were likely to experience a more favorable treatment course than those who switched from olanzapine to risperidone. Given the nature of observational study design and small sample size, additional studies are warranted

Efficacy and safety of ixekizumab in patients with plaque psoriasis across different degrees of disease severity: results from UNCOVER-2 and UNCOVER-3

PURPOSE: To evaluate short- and long-term efficacy and safety of ixekizumab in patients according to psoriasis severity. MATERIALS AND METHODS: Data were integrated from clinical trials (UNCOVER-2, UNCOVER-3). Patients received placebo, 80-mg ixekizumab every 2 weeks (IXEQ2W), every 4 weeks (IXEQ4W), or 50-mg etanercept (ETN) biweekly for 12 weeks, then open-label IXEQ4W (UNCOVER-3). Psoriasis severity was categorized by baseline Psoriasis Area and Severity Index (PASI /=20). Efficacy was evaluated by percentage reaching PASI 75, 90, 100, and absolute PASI /=20 (vs. PASI /=20 vs. PASI <20 patients across treatments reached PASI </=5, </=2, and </=1 at Week 12. Efficacy was maintained during 156 weeks of ixekizumab treatment with no differences between groups. The IXEQ2W safety profile was similar between groups except for injection-site reactions (significantly higher in PASI <20). CONCLUSIONS: Ixekizumab demonstrated a high level of efficacy and had a consistent safety profile in patients with different baseline psoriasis severity levels

The Smelling Principle of Vetiver Oil, Unveiled by Chemical Synthesis

Vetiver oil, produced on a multiton‐scale from the roots of vetiver grass, is one of the finest and most popular perfumery materials, appearing in over a third of all fragrances. It is a complex mixture of hundreds of molecules and the specific odorant, responsible for its characteristic suave and sweet transparent, woody‐ambery smell, has remained a mystery until today. Herein, we prove by an eleven‐step chemical synthesis, employing a novel asymmetric organocatalytic Mukaiyama–Michael addition, that (+)‐2‐epi‐ziza‐6(13)en‐3‐one is the active smelling principle of vetiver oil. Its olfactory evaluation reveals a remarkable odor threshold of 29 picograms per liter air, responsible for the special sensuous aura it lends to perfumes and the quasi‐pheromone‐like effect it has on perfumers and consumers alike

Cell Movement patterns during gastrulation in the chick are controlled by positive and negative chemotaxis mediated by FGF4 and FGF8

AbstractDuring gastrulation in amniotes, epiblast cells ingress through the primitive streak and migrate away to form endodermal, mesodermal, and extraembryonic structures. Here we analyze the detailed movement trajectories of cells emerging at different anterior-posterior positions from the primitive streak, using in vivo imaging of the movement of GFP-tagged streak cells. Cells emerging at different anterior-posterior positions from the streak show characteristic cell migration patterns, in response to guidance signals from neighboring tissues. Streak cells are attracted by sources of FGF4 and repelled by sources of FGF8. The observed movement patterns of anterior streak cells can be explained by an FGF8-mediated chemorepulsion of cells away from the streak followed by chemoattraction toward an FGF4 signal produced by the forming notochord