Die Bedeutung DNA-methylierender Enzyme für die Entstehung von Medulloblastomen und supratentoriellen primitiven neuroektodermalen Tumoren (stPNET) des zentralen Nervensystems im Kindesalter

Tumoren des ZNS sind die zweithäufigsten Neoplasien im Kindesalter. Einen möglichen Baustein der Tumorgenese dieser Tumoren (Medulloblastome, stPNET) stellt eine Veränderung des DNA-Methylierungsmusters (globale Hypomethylierung, Hypermethylierung von Promotorsequenzen) dar. Diese Veränderungen des Methylierungsmusters beruhen nach heutigem Wissensstand auf einer alterierten DNA-Methyltransferase-Aktivität. In dieser Arbeit wurde die Expression der DNA-Methyltransferasen gemessen. Abschließend wurden die Ergebnisse mit den klinischen Daten des Patientenkollektivs korreliert. Die mRNA-Expression der DNMT3b stellte sich in allen Tumorproben verglichen mit der Kontrollgruppe signifikant erhöht dar; während weder für DNMT1 (außer in den Zelllinien) noch für DNMT3a in den Tumorgeweben signifikant erhöhte mRNA-Level nachgewiesen werden konnten

Optogenetic stimulation effectively enhances intrinsically generated network synchrony

Synchronized bursting is found in many brain areas and has also been implicated in the pathophysiology of neuropsychiatric disorders such as epilepsy, Parkinson’s disease, and schizophrenia. Despite extensive studies of network burst synchronization, it is insufficiently understood how this type of network wide synchronization can be strengthened, reduced, or even abolished. We combined electrical recording using multi-electrode array with optical stimulation of cultured channelrhodopsin-2 transducted hippocampal neurons to study and manipulate network burst synchronization. We found low frequency photo-stimulation protocols that are sufficient to induce potentiation of network bursting, modifying bursting dynamics, and increasing interneuronal synchronization. Surprisingly, slowly fading-in light stimulation, which substantially delayed and reduced light-driven spiking, was at least as effective in reorganizing network dynamics as much stronger pulsed light stimulation. Our study shows that mild stimulation protocols that do not enforce particular activity patterns onto the network can be highly effective inducers of network-level plasticity

Growing neuronal islands on multi-electrode arrays using an accurate positioning-μCP device

Background: Multi-electrode arrays (MEAs) allow non-invasive multi-unit recording in-vitro from cultured neuronal networks. For sufficient neuronal growth and adhesion on such MEAs, substrate preparation is required. Plating of dissociated neurons on a uniformly prepared MEA's surface results in the formation of spatially extended random networks with substantial inter-sample variability. Such cultures are not optimally suited to study the relationship between defined structure and dynamics in neuronal networks. To overcome these shortcomings, neurons can be cultured with pre-defined topology by spatially structured surface modification. Spatially structuring a MEA surface accurately and reproducibly with the equipment of a typical cell-culture laboratory is challenging. New method: In this paper, we present a novel approach utilizing micro-contact printing (mu CP) combined with a custom-made device to accurately position patterns on MEAs with high precision. We call this technique AP-mu CP (accurate positioning micro-contact printing). Comparison with existing methods: Other approaches presented in the literature using mu CP for patterning either relied on facilities or techniques not readily available in a standard cell culture laboratory, or they did not specify means of precise pattern positioning. Conclusion: Here we present a relatively simple device for reproducible and precise patterning in a standard cell-culture laboratory setting. The patterned neuronal islands on MEAs provide a basis for high throughput electrophysiology to study the dynamics of single neurons and neuronal networks

Immunosuppression and Renal Outcome in Congenital and Pediatric Steroid-Resistant Nephrotic Syndrome

Background and objectives: Mutations in podocyte genes are associated with steroid-resistant nephrotic syndrome (SRNS), mostly affecting younger age groups. To date, it is unclear whether these patients benefit from intensified immunosuppression with cyclosporine A (CsA). The aim of this study was to evaluate the influence of podocyte gene defects in congenital nephrotic syndrome (CNS) and pediatric SRNS on the efficacy of CsA therapy and preservation of renal function

Recessive Missense Mutations in Lamb2 Expand the Clinical Spectrum of Lamb2-Associated Disorders

Congenital nephrotic syndrome is clinically and genetically heterogeneous. The majority of cases can be attributed to mutations in the genes NPHS1, NPHS2, and WT1. By homozygosity mapping in a consanguineous family with isolated congenital nephrotic syndrome, we identified a potential candidate region on chromosome 3p. The LAMB2 gene, which was recently reported as mutated in Pierson syndrome (microcoria-congenital nephrosis syndrome; OMIM #609049), was located in the linkage interval. Sequencing of all coding exons of LAMB2 revealed a novel homozygous missense mutation (R246Q) in both affected children. A different mutation at this codon (R246W), which is highly conserved through evolution, has recently been reported as causing Pierson syndrome. Subsequent LAMB2 mutational screening in six additional families with congenital nephrotic syndrome revealed compound heterozygosity for two novel missense mutations in one family with additional nonspecific ocular anomalies. These findings demonstrate that the spectrum of LAMB2-associated disorders is broader than previously anticipated and includes congenital nephrotic syndrome without eye anomalies or with minor ocular changes different from those observed in Pierson syndrome. This phenotypic variability likely reflects specific genotypes. We conclude that mutational analysis in LAMB2 should be considered in congenital nephrotic syndrome, if no mutations are found in NPHS1, NPHS2, or WT1.WoSScopu