Funktionelle und molekulare Charakterisierung von Kaliumkanälen in hippocampalen Astrozyten

Für die Funktion von Astrozyten in der zerebralen Ionen-, Transmitter- und Metabolitenregulation sowie Kontrolle des zerebralen Blutflusses ist ihre hohe Kaliumleitfähigkeit essentiell. Unter pathophysiologischen Bedingungen kommt es oft zu einer lokalen Azidose und die homöosthatische Funktion von Astrozyten ist eingeschränkt. Der Einfluss extrazellulärer Azidose auf die Kaliumleitfähigkeit von hippocampalen Astrozyten der Maus ist jedoch bislang unzureichend verstanden und wird in der vorliegenden Arbeit mit neurophysiologischen und molekularbiologischen Methoden untersucht. Hierzu erfolgen Patch-Clamp-Experimente an akut isolierten Astrozyten des murinem Hippocampus und einem heterologen Expressionssystem unter Applikation verschiedener pH-Werte und Ionenkanalmodulatoren, sowie molekularbiologische Experimente auf Transkriptionsebene mittels Einzelzell-RT-PCR und semiquantitativer RT-PCR. Extrazelluläre Azidifikation führte in Patch-Clamp-Experimenten zu einer Reduktion der astrozytären Kaliumströme. Dies ließ sich in Experimenten an Kir4.1-transfizierten Zellen eines heterologen Expressionssystems nachvollziehen und erfolgt somit vermutlich durch Modulation von Kir-Kanälen. Nach Blockade von Kir-Kanälen führte eine Azidifikation zu einer Vergrößerung der residuellen Kaliumleitfähigkeit hippocampaler Astrozyten. Diese Aktivierung wurde durch Modulatoren von TREK-1-Kanälen aus der Familie der K2P-Kanäle nachgebildet. Molekularbiologische Experimente bestätigten die astrozytäre Expression der K2P-Kanäle TREK-1 und TWIK-1, während TASK-Kanäle nicht nachweisbar waren. Elektrophysiologisch und auf Transkriptionsbene fanden sich keine Hinweise auf eine funktionelle Expression von ASIC und TRPV1-Kanälen in hippocampalen Astrozyten. Zusammenfassend erlaubt die Zusammenstellung astrozytärer Kaliumkanäle die Tolerierung transienter Azidifikation

Mixed-order Ambisonics recording and playback for improving horizontal directionality

Planar (2D) and periphonic (3D) higher-order Ambisonics (HOA) systems are widely used to reproduce spatial properties of acoustic scenarios. Mixed-order Ambisonics (MOA) systems combine the benefit of higher order 2D systems, i.e. a high spatial resolution over a larger usable frequency bandwidth, with a lower order 3D system to reproduce elevated sound sources. In order to record MOA signals, the location of the microphones on a hard sphere were optimized to provide a robust MOA encoding. A detailed analysis of the encoding and decoding process showed that MOA can improve both the spatial resolution in the horizontal plane and the usable frequency bandwidth for playback as well as recording. Hence the described MOA scheme provides a promising method for improving the performance of current 3D sound reproduction systems.7 page(s

Altersabhängige Adenosin–vermittelte Relaxation des Musculus detrusor vesicae der Ratte

Adenosin wirkt dosisabhängig relaxierend auf die Blasenmuskulatur. Es besteht eine Abhängigkeit zwischen Alter und Effektivität von Adenosin. Die vier beschriebenen Adenosinrezeptoren konnten im Rahmen dieser Arbeit bestätigt werden. Die Rezeptoren A1, A2A und A3 zeigen keine relevanten Unterschiede in ihrer relativen Expression. Bestätigt werden konnte eine stärkere Expression des A2B–Rezeptors. Mit zunehmendem Alter besteht ein Anstieg der Expression des A1–Rezeptors (r = 0,61, p < 0,05). Worauf der Wirkungsverlust von Adenosin begründet ist, sollte Gegenstand weiterer Forschung sein

High costs, low quality of life, reduced survival, and room for improving treatment: an analysis of burden and unmet needs in glioma

Gliomas are a group of heterogeneous tumors that account for substantial morbidity, mortality, and costs to patients and healthcare systems globally. Survival varies considerably by grade, histology, biomarkers, and genetic alterations such as IDH mutations and MGMT promoter methylation, and treatment, but is poor for some grades and histologies, with many patients with glioblastoma surviving less than a year from diagnosis. The present review provides an introduction to glioma, including its classification, epidemiology, economic and humanistic burden, as well as treatment options. Another focus is on treatment recommendations for IDH-mutant astrocytoma, IDH-mutant oligodendroglioma, and glioblastoma, which were synthesized from recent guidelines. While recommendations are nuanced and reflect the complexity of the disease, maximum safe resection is typically the first step in treatment, followed by radiotherapy and/or chemotherapy using temozolomide or procarbazine, lomustine, and vincristine. Immunotherapies and targeted therapies currently have only a limited role due to disappointing clinical trial results, including in recurrent glioblastoma, for which the nitrosourea lomustine remains the de facto standard of care. The lack of treatment options is compounded by frequently suboptimal clinical practice, in which patients do not receive adequate therapy after resection, including delayed, shortened, or discontinued radiotherapy and chemotherapy courses due to treatment side effects. These unmet needs will require significant efforts to address, including a continued search for novel treatment options, increased awareness of clinical guidelines, improved toxicity management for chemotherapy, and the generation of additional and more robust clinical and health economic evidence

Deliberate Switching of Single Photochromic Triads

Photochromic molecules can be reversibly converted between two bistable conformations by light, and are considered as promising building blocks in novel macromolecular structures for sensing and imaging techniques. We have studied individual molecular triads consisting of two strong fluorophores (perylene bisimide) that are covalently linked via a photochromic unit (dithienylcyclopentene) and distinguished between deliberate switching and spontaneous blinking. It was verified that the probability for observing deliberate light-induced switching of a single triad (rather than stochastic blinking) amounts to 0.8 ± 0.1. In a few exceptional cases this probability can exceed 0.95. These numbers are sufficiently large for application in sensitive biosensing, and super-resolution imaging. This opens the possibility to develop devices that can be controlled by an external optical stimulus on a truly molecular length scale

Comparison of treatment response, remission rate and drug adherence in polyarticular juvenile idiopathic arthritis patients treated with etanercept, adalimumab or tocilizumab

Background Treatment response, remission rates and compliance in patients with polyarticular juvenile idiopathic arthritis (polyJIA) treated with adalimumab, etanercept, or tocilizumab were analyzed in clinical practice. Methods Data collected in the German BIKER registry were analyzed in patients with polyJIA who started treatment with approved biologics, adalimumab, etanercept or tocilizumab, from 2011 to 2015. Baseline patient characteristics, treatment response, safety and drug survival were compared. Results Two hundred thirty- six patient started adalimumab, 419 etanercept and 74 tocilizumab, with differences in baseline patient characteristics. Baseline Juvenile Disease Activity Score (JADAS)10 (mean ± SD) in the adalimumab/etanercept/tocilizumab cohorts was 12.1+/−7.6, 13.8 ± 7.1 and 15.1 ± 7.4, respectively (adalimumab vs etanercept, p = 0.01), and Childhood Health Assessment Questionnaire (CHAQ)-disability index scores was 0.43 ± 0.58, 0.59 ± 0.6 and 0.63 ± 0.55, respectively (adalimumab vs etanercept, p < 0.001). Uveitis history was more frequent in the adalimumab cohort (OR 5.73; p < 0.001). Balanced patients’ samples were obtained by a generalized propensity score to adjust for baseline differences. Pediatric ACR30/50/70/90 criterion improvement after 3 months treatment was achieved by 68%/60%/42%/24% in the etanercept cohort, 67%/59%/43%/27% in the adalimumab cohort and 61%/52%/35%/26% in the tocilizumab cohort. At 24 months, JADAS minimal disease activity was achieved in 52.4%/61.3%/52.4% and JADAS remission in 27.9%/34.8%/27.9% patients in the adalimumab/etanercept/tocilizumab cohorts, respectively. Etanercept was used in 95.5% of patients as a first biologic, adalimumab in 50.8% and tocilizumab in 20.2%. There were no important differences in efficacy between first-line and second-line use of biologics. In total 60.4%/49.4%/31.1% patients discontinued adalimumab/etanercept/tocilizumab, respectively (HR for adalimumab 1.67; p < 0.001; HR for tocilizumab 0.35; p = 0.001). Drug survival rates did not differ significantly in patients on biologic monotherapy compared with combination therapy with methotrexate. Over 4 years observation under etanercept/adalimumab/tocilizumab, 996/386/103 adverse events, and 148/119/26 serious adverse events, respectively, were reported. Conclusions In clinical practice, etanercept is most frequently used as first-line biologic. Adalimumab/etanercept/tocilizumab showed comparable efficacy toward polyJIA. Overall, tolerance was acceptable. Interestingly, compliance was highest with tocilizumab and lowest with adalimumab. This study provides the first indication for the comparison of different biologic agents in polyarticular JIA based on observational study data with all their weaknesses and demonstrates the need for well-controlled head-to-head studies for confirmation

Mean Platelet Volume/Platelet Count Ratio and Risk of Progression in Glioblastoma

ObjectiveThe mean platelet volume/platelet count (MPV/PC) ratio is an emerging biomarker in selected types of cancer. The objective of this study is to analyze the association of MPV/PC ratio with progression and survival in glioblastoma (GB) patients, with consideration of patient demographics, tumor morphology, extent of resection, molecular pathology, and oncological therapy.MethodsOne hundred ninety-one patients with newly diagnosed GB were analyzed retrospectively. MPV/PC ratio groups (≤ or &gt;0.0575) were dichotomized into low-MPV/PC ratio (≤0.0575) and high-MPV/PC ratio (&gt;0.0575) groups according to the most significant split in the log-rank test.ResultsA two-sided Fisher’s exact test showed no significant differences in the confounders between the low- and high-MPV/PC ratio groups. The median progression-free survival (PFS) was 9.0 months (95% CI=8.0–10.0) in the low-MPV/PC ratio group (n=164) and 6.0 months (95% CI=3.0–8.9) in the high-MPV/PC group (n=28) (p=0.013). Multivariate Cox regression analysis including the O-6-methylguanine-DNA methyltransferase (MGMT) status, age (≤/&gt;65 years), baseline Karnofsky Performance Status (KPS), and MPV/PC ratio showed high-MPV/PC ratio as a predictor of progression (p =0.04, HR=1.61, 95% CI=1.01–2.57). In the subgroup of IDH1 wild-type GBs, high MPV/PC ratio was still a significant predictor for shortened PFS (p=0.042, HR=1.60, 95% CI=1.02–2.52). MPV/PC ratio showed no significant effect in the overall survival (OS) analysis. Median OS was 15.0 months in the high-MPV/PC ratio group and 21.0 months in the low-MPV/PC ratio group (p=0.22).ConclusionMPV/PC ratio may independently predict the progression-free survival rates of patients with glioblastoma multiforme

Antagonism of the mammalian target of rapamycin selectively mediates metabolic effects of epidermal growth factor receptor inhibition and protects human malignant glioma cells from hypoxia-induced cell death

Although inhibition of the epidermal growth factor receptor is a plausible therapy for malignant gliomas that, in vitro, enhances apoptosis, the results of clinical trials have been disappointing. The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that integrates starvation signals and generates adaptive responses that aim at the maintenance of energy homeostasis. Antagonism of mTOR has been suggested as a strategy to augment the efficacy of epidermal growth factor receptor inhibition by interfering with deregulated signalling cascades downstream of Akt. Here we compared effects of antagonism of mTOR utilizing rapamycin or a small hairpin RNA-mediated gene silencing to those of epidermal growth factor receptor inhibition or combined inhibition of epidermal growth factor receptor and mTOR in human malignant glioma cells. In contrast to epidermal growth factor receptor inhibition, mTOR antagonism neither induced cell death nor enhanced apoptosis induced by CD95 ligand or chemotherapeutic drugs. However, mTOR inhibition mimicked the hypoxia-protective effects of epidermal growth factor receptor inhibition by maintaining adenosine triphosphate levels. These in vitro experiments thus challenge the current view of mTOR as a downstream target of Akt that mediates antiapoptotic stimuli. Under the conditions of the tumour microenvironment, metabolic effects of inhibition of epidermal growth factor receptor, Akt and mTOR may adversely affect outcome by protecting the hypoxic tumour cell fractio

Association of perioperative adverse events with subsequent therapy and overall survival in patients with WHO grade III and IV gliomas

Background Maximum safe resection followed by chemoradiotherapy as current standard of care for WHO grade III and IV gliomas can be influenced by the occurrence of perioperative adverse events (AE). The aim of this study was to determine the association of AE with the timing and choice of subsequent treatments as well as with overall survival (OS). Methods Prospectively collected data of 283 adult patients undergoing surgery for WHO grade III and IV gliomas at the University Hospital Zurich between January 2013 and June 2017 were analyzed. We assessed basic patient characteristics, KPS, extent of resection, and WHO grade, and we classified AE as well as modality, timing of subsequent treatment (delay, interruption, or non-initiation), and OS. Results In 117 patients (41%), an AE was documented between surgery and the 3-month follow-up. There was a significant association of AE with an increased time to initiation of subsequent therapy (p = 0.005) and a higher rate of interruption (p < 0.001) or non-initiation (p < 0.001). AE grades correlated with time to initiation of subsequent therapy (p = 0.038). AEs were associated with shorter OS in univariate analysis (p < 0.001). Conclusion AEs are associated with delayed and/or altered subsequent therapy and can therefore limit OS. These data emphasize the importance of safety within the maximum-safe-resection concept

Leukoencephalopathy after prophylactic whole-brain irradiation with or without hippocampal sparing: a longitudinal magnetic resonance imaging analysis

PURPOSE Neurocognitive changes are well described after prophylactic or therapeutic whole-brain radiotherapy (WBRT) and have been reported as early as 3 months after radiotherapy (RT). Therefore, WBRT with protection of the hippocampal region (hippocampal avoidance, HA) has been proposed to preserve neurocognition. Our aim was to compare the risk of leukoencephalopathy after prophylactic cranial irradiation (PCI) with or without HA. METHODS Patients with small-cell lung cancer who received either lateral-opposed field PCI (non-HA-PCI; n = 9) or hippocampus avoidance PCI (HA-PCI; n = 9) with available magnetic resonance imaging (MRI) follow-up were identified and age matched. Pre-therapeutic and follow-up MRI after RT was analysed for leukoencephalopathy based on the Fazekas score. Bilateral cortical and subcortical brain structures were segmented and analysed for alterations in dosimetric parameters and volumes. RESULTS There was no significant difference of Fazekas scores between groups at baseline. Fazekas score differed in post-treatment with a median of 1 in the HA-PCI group and 2 in the non-HA-PCI group (p = 0.007). Significant increase of Fazekas score over time after RT was observed for HA-PCI patients (p = 0.001) but not for non-HA-PCI patients. Dmax (highest radiation dose) and brain volume receiving doses >25Gy were higher in HA-PCI patients. There were no significant volumetric differences for segmented brain structures between groups. CONCLUSION Radiological changes are more prominent after HA-PCI than after non-HA-PCI. Although no standardised neurocognitive testing was performed, the significantly increased Fazekas scores after HA-PCI are expected to interfere with neurocognitive function. Prospective long-term neurocognitive studies are warranted before HA-PCI is implemented in routine clinical practice