Änne Glass

Small molecule GSK-3 inhibitors increase neurogenesis of human neural progenitor cells

Human neural progenitor cells provide a source for cell replacement therapy to treat neurodegenerative diseases. Therefore, there is great interest in mechanisms and tools to direct the fate of multipotent progenitor cells during their differentiation to increase the yield of a desired cell type. We tested small molecule inhibitors of glycogen synthase kinase-3 (GSK-3) for their functionality and their influence on neurogenesis using the human neural progenitor cell line ReNcell VM. Here we report the enhancement of neurogenesis of human neural progenitor cells by treatment with GSK-3 inhibitors. We tested different small molecule inhibitors of GSK-3 i.e. LiCl, sodium-valproate, kenpaullone, indirubin-3-monoxime and SB-216763 for their ability to inhibit GSK-3 in human neural progenitor cells. The highest in situ GSK-3 inhibitory effect of the drugs was found for kenpaullone and SB-216763. Accordingly, kenpaullone and SB-216763 were the only drugs tested in this study to stimulate the Wnt/β-catenin pathway that is antagonized by GSK-3. Analysis of human neural progenitor differentiation revealed an augmentation of neurogenesis by SB-216763 and kenpaullone, without changing cell cycle exit or cell survival. Small molecule inhibitors of GSK-3 enhance neurogenesis of human neural progenitor cells and may be used to direct the differentiation of neural stem and progenitor cells in therapeutic applications.

Peroxisome proliferator - activated receptor γ overexpression inhibits pro-fibrogenic activities of immortalised rat pancreatic stellate cells

Pancreatic stellate cells (PSCs) play a key role in the development of pancreatic fibrosis, a constant feature of chronic pancreatitis and pancreatic cancer. In response to pro‐fibrogenic mediators, PSCs undergo an activation process that involves proliferation, enhanced production of extracellular matrix proteins and a phenotypic transition towards myofibroblasts. Ligands of the peroxisome proliferator‐activated receptor gamma (PPARγ), such as thiazolidinediones, are potent inhibitors of stellate cell activation and fibrogenesis in pancreas and liver. The effects of PPARγ ligands, however, however, are at least in part mediated through PPARγ‐independent pathways. Here, we have chosen a different approach to study regulatory functions of PPARγ in PSCs. Using immortalised rat PSCs, we have established a model of tetracycline (tet)‐regulated PPARγ over‐expression. Induction of PPARγ expression strongly inhibited proliferation and enhanced the rate of apoptotic cell death. Furthermore, PPARγ‐overexpressing cells synthesised less collagen than controls. To monitor effects of PPARγ on PSC gene expression, we employed Affymetrix microarray technology. Using stringent selection criteria, we identified 21 up‐ and 19 down‐regualated genes in PPARγ‐overexpressing cells. Most of the corresponding gene products are either involved in lipid metabolism, play a role in signal transduction, or are secreted molecules that regulate cell growth and differentition. In conclusion, our data suggest an active role of PPARγ in the induction of a quiescent PSC phenotype. PPARγ‐regulated genes in PSCs may serve as novel targets for the development of antifibrotic therapies.

Deep brain stimulation in a rat model modulates TH, CaMKIIa and Homer1 gene expression

High‐frequency stimulation (HFS) of subthalamic nucleus (STN) is a therapy for late‐stage Parkinsons disease. Its mechanisms of action are not yet fully understood. In the present study, gene expression analyses were performed in a rat model of Parkinsons disease, i.e. striatal 6‐hydroxydopamine (6‐OHDA) lesion. Using microarrays, gene expression was analysed in 1‐mm‐thick sagittal brain slices, including basal ganglia of five groups of male Wistar rats. These were unmanipulated rats (group A), unlesioned rats with implanted electrode but without stimulation (group B), unlesioned, stimulated rats (group C), 6‐OHDA‐lesioned rats with implanted electrode but without stimulation (group D), and finally 6‐OHDA‐lesioned and stimulated rats (group E). A statistically significant downregulation of tyrosine hydroxylase (TH) mRNA expression induced by 6‐OHDA lesion and an HFS‐induced TH upregulation in 6‐OHDA‐lesioned rats could be detected. It could be hypothesized that the HFS‐induced upregulation of TH is the result of neuronal STN modulation and mediated via projections from STN to substantia nigra pars compacta. Furthermore, a downregulation of calcium/calmodulin‐dependent protein kinase type IIA and Homer1 was observed. This downregulation could result in a reduced sensitivity towards glutamate in basal ganglia downstream of STN.

The Autoimmune Disease Database: a dynamically compiled literature-derived database

BackgroundAutoimmune diseases are disorders caused by an immune response directed against the bodys own organs, tissues and cells. In practice more than 80 clinically distinct diseases, among them systemic lupus erythematosus and rheumatoid arthritis, are classified as autoimmune diseases. Although their etiology is unclear these diseases share certain similarities at the molecular level i.e. susceptibility regions on the chromosomes or the involvement of common genes. To gain an overview of these related diseases it is not feasible to do a literary review but it requires methods of automated analyses of the more than 500,000 Medline documents related to autoimmune disorders.ResultsIn this paper we present the first version of the Autoimmune Disease Database which to our knowledge is the first comprehensive literature-based database covering all known or suspected autoimmune diseases. This dynamically compiled database allows researchers to link autoimmune diseases to the candidate genes or proteins through the use of named entity recognition which identifies genes/proteins in the corresponding Medline abstracts. The Autoimmune Disease Database covers 103 autoimmune disease concepts. This list was expanded to include synonyms and spelling variants yielding a list of over 1,200 disease names. The current version of the database provides links to 541,690 abstracts and over 5,000 unique genes/proteins.ConclusionThe Autoimmune Disease Database provides the researcher with a tool to navigate potential gene-disease relationships in Medline abstracts in the context of autoimmune diseases.

Automatic construction of gene relation networks using text mining and gene expression data

Microarray gene expression analysis is a powerful high-throughput technique that enables researchers to monitor the expression of thousands of genes simultaneously. Using this methodology huge amounts of data are produced which have to be analysed. Clustering algorithms are used to group genes together based on a predefined distance measure. However, clustering algorithms do not necessarily group the genes in a biological meaningful way. Additional information is needed to improve the identification of disease relevant genes. The primary objective of our project is to support the analysis of microarray gene expression data by construction of gene relation networks (GRNs). Required information can not be found in a structured representation like a database. In contrast, a large number of relations are described in biomedical literature. The main outcome of this project is the implementation of a software system that provides clinicians and researchers with a tool that supports the analysis of microarray gene expression data by mapping known relationships from the biomedical literature to local gene expression experiments.

Representation of individual gene expression in completely pooled mRNA samples

Designing microarray experiments, scientists are often confronted with the question of pooling due to financial constraints, but discussion of the validity of pooling tends toward a sub-pooling recommendation. Since complete pooling protocols can be considered part of sub-pooling designs, gene expression data from three complete pooling experiments were analyzed. Data from complete pooled versus individual mRNA samples of rat brain tissue were compared to answer the question whether the pooled sample represents individual samples in small-sized experiments. Our analytic approach provided clear results concerning the Affymetrix® MAS 5.0 signal and detection call parameters. Despite a strong similarity of arrays within experimental groups, the individual signals were evidently not appropriately represented in the pooled sample, with slightly more than half of all the genes considered. Our analysis reveals problems in cases of small complete pooling designs with less than six subjects pooled.

Cardiac Cell Therapies for the Treatment of Acute Myocardial Infarction: A Meta-Analysis from Mouse Studies.

Aims: Stem cell-based regenerative therapies for the treatment of ischemic myocardium are currently a subject of intensive investigation. A variety of cell populations have been demonstrated to be safe and to exert some positive effects in human Phase I and II clinical trials, however conclusive evidence of efficacy is still lacking. While the relevance of animal models for appropriate pre-clinical safety and efficacy testing with regard to application in Phase III studies continues to increase, concerns have been expressed regarding the validity of the mouse model to predict clinical results. Against the background that hundreds of preclinical studies have assessed the efficacy of numerous kinds of cell preparations - including pluripotent stem cells - for cardiac repair, we undertook a systematic re-evaluation of data from the mouse model, which initially paved the way for the first clinical trials in this field. Methods and Results: A systematic literature screen was performed to identify publications reporting results of cardiac stem cell therapies for the treatment of myocardial ischemia in the mouse model. Only peer-reviewed and placebo-controlled studies using magnet resonance imaging (MRI) for left ventricular ejection fraction (LVEF) assessment were included. Experimental data from 21 studies involving 583 animals demonstrate a significant improvement in LVEF of 8.59%+/- 2.36; p=.012 (95% CI, 3.7–13.8) compared with control animals. Conclusion: The mouse is a valid model to evaluate the efficacy of cell-based advanced therapies for the treatment of ischemic myocardial damage. Further studies are required to understand the mechanisms underlying stem cell based improvement of cardiac function after ischemia.

The role of specimen radiography in breast-conserving therapy of ductal carcinoma in situ

BACKGROUND To assess the role of intraoperative specimen radiography (SR) and to define risk factors for positive margins in breast-conserving therapy (BCT) of ductal carcinoma in situ (DCIS). METHODS In a retrospective study in calcification-associated DCIS treated with BCT between January 2009 and December 2011, digital mammographs and SR were reviewed and radiological margin width was determined. Clinical, radiological, and histological data were correlated with surgical histological data, and a histologically free margin of at least 2 mm was taken as evidence of successful BCT. RESULTS 47/91 patients (51.6%) fulfilling the inclusion criteria had histologically involved surgical margins. Univariate analyses revealed DCIS size, mammographic extension of calcification, presence of comedo necrosis, negative progesterone receptor status, and a small radiological margin on SR to be risk factors for unsuccessful BCT. Receiver Operating Characteristic (ROC) analysis showed a radiological margin width of 4 mm to be optimal, with a sensitivity of 72.3% and specificity of 52.3%. The likelihood of surgical free margins was increased 2.9-fold with a radiological margin width ≥4 mm. On multivariate logistic regression analysis, only histological DCIS size >20 mm clearly emerged as an independent predictive factor for surgically involved margins (p < 0.001), while an SR margin <4 mm trended toward significance (p = 0.066). CONCLUSIONS SR is a reliable method for predicting free surgical margins in non-invasive breast cancer where a minimum radiological free margin of 4 Fmm is achieved. However, histological DCIS size remains the most important factor determining successful BCT.

Clinical factors are associated with vitamin D levels in IBD patients: A retrospective analysis: Clinical factors and vitamin D in IBD

There is growing evidence that vitamin D deficiency plays a role in the development and the course of inflammatory bowel disease (IBD). However, the correlation between vitamin D deficiency and clinical parameters in IBD is still not completely understood.

Morphologic and biometric evaluation of chick embryo eyes in ovo using 7 Tesla MRI

The purposes of this study were (1) to characterize embryonic eye development during incubation in ovo and (2) to analyze the putative influence of repetitive ultrahigh-field MRI (UHF-MRI) measurements on this development. A population of 38 fertilized chicken eggs was divided into two sub-groups: two eggs (Group A) were examined repeatedly during the developmental period from embryonic day 1 (E1) to embryonic day 20 (E20) to evaluate the influence of daily MRI scanning. A second larger group of 36 eggs was examined pairwise on one day only, from E3 to E20, and the embryos were sacrificed immediately after MR imaging (Group B). Fast T2-weighted MR sequences provided biometric data on the eye with an in-plane resolution of 74 μm. The data show rapid growth of the eye with a steep increase in intraocular dimensions in all axis directions and in eyeball volume during initial development up to E10, followed by a phase of reduced growth rate in later developmental stages. Comparison of the two groups revealed no differences in ocular development.