Age-dependent gene expression profile and protein expression in a transgenic rat model of Huntington's disease

Polyglutamine‐induced changes in gene expression have been demonstrated by using several mouse models of Huntington's disease (HD), which express extreme numbers of CAG repeats. We have recently developed a transgenic rat model of HD carrying a truncated huntingtin fragment with 51 CAG repeats, which is in the range seen in adult HD patients. For further evaluation, we have performed microarray analyses on whole brains of transgenic rats at 3 and 12 months of age and correlated it with protein expression by Western blot analysis. We found that genes functionally associated with gene expression and behavior were differently regulated already at 3 months of age, whereas at 12 months of age especially genes related to neurological diseases and cell‐to‐cell signaling and interaction were dysregulated. A detailed analysis of canonical pathways revealed that at 3 months of age genes in calcium signaling and synaptic long term potentation pathways were altered, while at 12 months of age, additionally, expression level of many genes implicated in Huntington's disease signaling, were changed.     

Online help-seeking in communities of practice: Modeling the acceptance of conceptual artifacts

Interactive online help systems are considered to be a fruitful supplement to traditional IT helpdesks, which are often overloaded. They often comprise user-generated FAQ collections playing the role of technology-based conceptual artifacts. Two main questions arise: how the conceptual artifacts should be used, and which factors influence their acceptance in a community of practice (CoP). Firstly, this paper offers a theoretical frame and a usage scenario for technology-based conceptual artifacts against the theoretical background of the academic help-seeking and CoP approach. Each of the two approaches is extensively covered by psychological and educational research literature, however their combination is not yet sufficiently investigated. Secondly, the paper proposes a research model explaining the acceptance of conceptual artifacts. The model includes users' expectations toward the artifact, perceived social influence and users' roles in the CoP as predictors of artifact use intention and actual usage. A correlational study conducted in an academic software users' CoP and involving structural equations modeling validates the model, suggesting thus a research line that is worth further pursuing. For educational practice, the study suggests three ways of supporting knowledge sharing in CoPs, i.e. use of technology-based conceptual artifacts, roles and division of labor, and purposeful communication in CoPs.     

Wenn es persönlich wird in der „personalisierten Medizin“: Aufklärung und Kommunikation aus klinischer Forscher- und Patientenperspektive im empirisch-ethischen Vergleich

Definition of the problem In clinical research and practice, the new paradigm of “personalised medicine” raises questions about necessity, expectations, possibilities and risks. In an ongoing empirical–ethical study, we explore the perspectives of both researchers and patients regarding the implementation of “personalised medicine” in the treatment of locally advanced rectal cancer. This study focuses on ethically relevant aspects in practice, including expectations towards, counseling on, and decision for “personalized” treatment, or research. Methods We conducted interviews (with 19 researchers and physicians and 28 patients) and participant observations during physician–patient consultations (n = 50). Arguments Uncovering differences and similarities in the perspectives of affected patients and physicians will allow potential conflicts in clinical practice to be detected and addressed as early as possible. Conclusions We were able to demonstrate that patients and physicians have different perspectives on “personalised medicine”. This might lead to conflicts in clinical practice that should be addressed as early as possible.     

Evaluation of a Yarrowia lipolytica Strain Collection for Its Lipid and Carotenoid Production Capabilities

The oleaginous yeast Yarrowia lipolytica is capable of accumulating large amounts of fatty acids in the form of lipids which can serve as a platform polymer for a variety of applications. Additionally, through heterologous gene expression, Y. lipolytica is capable of producing carotenoids. Due to the observation that Y. lipolytica exhibits a high phenotypic inter‐strain variability, robotics and microwell scale cultivations are applied to examine 12 wild type strains of a Y. lipolytica collection. The strains are characterized with respect to their metabolic capabilities for fatty acid production as well as genetically manipulated to produce beta‐carotene. Furthermore, growth and production behavior of the strain collection at different temperatures as well as initial pH are assessed. A molecular discrimination between the strains is achieved by internal transcribed spacer (ITS)‐sequencing and polymerase chain reaction (PCR)‐based methods. The best performing strain with respect to lipid production produces ≈2% lipids per dry cell weight (DCW) and 8 mg g^?1 beta‐carotenoids in yeast nitrogen base (YNB) media. All strains show robust growth from 28 to 34 °C. Practical Applications: Unlocking nature's potential by screening natural isolates shows that even on inter‐strain level sufficient phenotypic diversity may arise. Automated growth‐based characterization of beta‐carotene‐producing strains in terms of media composition, effect of initial pH, and temperature tolerance shows that with modern cultivation techniques, rapid characterization of strain collections is feasible. Combining results of beta‐carotene and lipid formation could help to balance both pathways to improve the storage of hydrophobic compounds in the lipid droplets. The generalized findings could be further transferred to improve the production of any valuable compound, derived from the mevalonate pathway.     

Neural Crest Stem Cells in Juvenile Angiofibromas

The etiology of juvenile angiofibroma (JA) has been a controversial topic for more than 160 years. Numerous theories have been proposed to explain this rare benign neoplasm arising predominately in adolescent males, focusing mainly on either the vascular or fibrous component. To assess our hypothesis of JA’s being a malformation arising from neural crest cells/remnants of the first branchial arch plexus, we performed immunohistochemical analyses of neural crest stem cells (NCSC) and epithelial-mesenchymal transition (EMT) candidates. Immunoexpression of the NCSC marker CD271^p75 was observed in all investigated JA’s (n = 22), mainly around the pathological vessels. Close to CD271^p75-positive cells, high MMP3-staining was also observed. Additionally, from one JA with sufficient material, RT-qPCR identified differences in the expression pattern of PDGFRβ, MMP2 and MMP3 in MACS^®-separated CD271^p75positive vs. CD271^p75 negative cell fractions. Our results, together with the consideration of the literature, provide evidence that JA’s represent a malformation within the first branchial arch artery/plexus remnants deriving from NCSC. This theory would explain the typical site of tumor origin as well as the characteristic tumor blood supply, whereas the process of EMT provides an explanation for the vascular and fibrous tumor component.     

Learning argumentation skills through the use of prompts for self-explaining examples.

Learning with self-explaining examples is an effective method in well-structured domains. The authors analyzed this method in teaching the complex skill of argumentation, experimentally comparing 4 conditions (N = 71 student teachers) that differed with respect to whether and how the processing of the examples was supported by self-explanation prompts. They found that examples of argumentation could be successfully used to teach declarative knowledge about argumentation. However, when the skill of argumentation is to be fostered, prompts that direct the learners' attention to the principles of argumentation should be used. The authors demonstrate that learning with self-explaining examples is also a promising method of enhancing skills in ill-structured domains such as argumentation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of the sequential extractions on the structure and the properties of single cell materials from apples

In order to evaluate the influence of disintegration on the structure and the properties of single cell wall materials from apples, parenchymatic single cells (MM) were extracted step by step with water (BM), chelating agents (CH), sodium chlorite/acetic acid mixture (CO) and sodium hydroxide/NaBH₄ (CA). The composition and the structure parameters of the dried materials obtained showed enhanced cell wall disintegration in the order MM, BM, CH, CO and CA. This disintegration was proved by decreasing yields and increasing glucose contents indicating a lower share of amorphous matrix and a higher share of cellulose-xyloglucan network with rising steps of the sequential extraction. However, systematic alterations of galacturonan content, bulk density, solid density and porosity with increasing cell wall disintegration were not found. The hydration properties, determined as swelling and water retention capacities, decreased in the order BM, MMCO, CH and CA. Also, the structure-viscous and viscoelastic properties of the rehydrated CWM in the decreasing order CH, CO, BM, MM and CA were not in agreement with the order of the cell wall disintegration as well as with the order of the hydration properties. The results show a complex and multivariate correlation between structure, physical state and properties.