Publications by authors named "Niklas Schwarz"

Background: Key functions of Ca signaling in rodent microglia include monitoring the brain state as well as the surrounding neuronal activity and sensing the danger or damage in their vicinity. Microglial Ca dyshomeostasis is a disease hallmark in many mouse models of neurological disorders but the Ca signal properties of human microglia remain unknown.

Methods: We developed a novel genetically-encoded ratiometric Ca indicator, targeting microglial cells in the freshly resected human tissue, organotypically cultured tissue slices and analyzed in situ ongoing Ca signaling of decades-old microglia dwelling in their native microenvironment.

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Article Synopsis
  • Investigating the human brain at the cellular level is difficult due to the fragility of neuronal tissue and limited human brain material.
  • Brain slices are useful for studying brain functions and diseases over extended periods, as this method overcomes the constraints of acute slices.
  • The paper provides a detailed protocol for long-term culturing of human brain slice cultures, discusses challenges in the process, and demonstrates their viability through various recording techniques and viral expression results.
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Optical metasurface technology promises an important potential for replacing bulky traditional optical components, in addition to enabling new compact and lightweight metasurface-based devices. Since even subtle imperfections in metasurface design or manufacture strongly affect their performance, there is an urgent need to develop proper and accurate protocols for their characterization, allowing for efficient control of the fabrication. We present non-destructive spectroscopic Mueller matrix ellipsometry in an uncommon off-specular configuration as a powerful tool for the characterization of orthogonal polarization beam-splitters based on a-Si:H nanopillars.

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Recently, variants in , coding for the potassium channel subunit K3.2, have been described as causative for various forms of epilepsy including genetic generalized epilepsy (GGE) and developmental and epileptic encephalopathy (DEE). Here, we report the functional characteristics of three additional variants of uncertain significance and one variant classified as pathogenic.

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The STX1B gene encodes the presynaptic protein syntaxin-1B, which plays a major role in regulating fusion of synaptic vesicles. Mutations in STX1B are known to cause epilepsy syndromes, such as genetic epilepsies with febrile seizures plus (GEFS+). Here, we reprogrammed skin fibroblasts from a female patient affected by GEFS+ to human induced pluripotent stem cells (iPSCs).

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Objective: Fibroblast Growth Factor 12 (FGF12) may represent an important modulator of neuronal network activity and has been associated with developmental and epileptic encephalopathy (DEE). We sought to identify the underlying pathomechanism of FGF12-related disorders.

Methods: Patients with pathogenic variants in FGF12 were identified through published case reports, GeneMatcher and whole exome sequencing of own case collections.

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Article Synopsis
  • The study focuses on Kv3.2, a potassium channel crucial for high-frequency brain firing and efficient action potential generation, examining its genetic variations linked to epilepsy.
  • Researchers analyzed clinical data and functional characteristics of Kv3.2 variants found in patients with different types of epilepsy, including cases like genetic generalized epilepsy and severe developmental epilepsy.
  • Results revealed that out of 18 identified variants, 10 were new and linked to severe epilepsy forms, leading to significant insights about Kv3.2's involvement in epilepsy and its role in regulating brain activity.
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Among genetic paroxysmal movement disorders, variants in ion channel coding genes constitute a major subgroup. Loss-of-function (LOF) variants in , the gene coding for K1.1 channels, are associated with episodic ataxia type 1 (EA1), characterized by seconds to minutes-lasting attacks including gait incoordination, limb ataxia, truncal instability, dysarthria, nystagmus, tremor, and occasionally seizures, but also persistent neuromuscular symptoms like myokymia or neuromyotonia.

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Developmental and epileptic encephalopathies are devastating disorders characterized by epilepsy, intellectual disability, and other neuropsychiatric symptoms, for which available treatments are largely ineffective. Following a precision medicine approach, we show for -encephalopathy that the K channel blocker 4-aminopyridine can antagonize gain-of-function defects caused by variants in the K1.2 subunit in vitro, by reducing current amplitudes and negative shifts of steady-state activation and increasing the firing rate of transfected neurons.

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Background: Proteopathic brain lesions are a hallmark of many age-related neurodegenerative diseases including synucleinopathies and develop at least a decade before the onset of clinical symptoms. Thus, understanding of the initiation and propagation of such lesions is key for developing therapeutics to delay or halt disease progression.

Methods: Alpha-synuclein (αS) inclusions were induced in long-term murine and human slice cultures by seeded aggregation.

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Neurons differentiated from induced pluripotent stem cells (iPSCs) typically show regular spiking and synaptic activity but lack more complex network activity critical for brain development, such as periodic depolarizations including simultaneous involvement of glutamatergic and GABAergic neurotransmission. We generated human iPSC-derived neurons exhibiting spontaneous oscillatory activity after cultivation of up to 6 months, which resembles early oscillations observed in rodent neurons. This behavior was found in neurons generated using a more "native" embryoid body protocol, in contrast to a "fast" protocol based on NGN2 overexpression.

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Patients with neurofibromatosis type 1 (NF1) have an increased risk for West syndrome (WS), but the underlying mechanisms linking NF1 and WS are unknown. In contrast to other neurocutaneous syndromes, intracerebral abnormalities explaining the course of infantile spasms (IS) are often absent and the seizure outcome is usually favorable. Several studies have investigated a potential genotype-phenotype correlation between and seizure susceptibility, but an association was not identified.

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Article Synopsis
  • Human cerebrospinal fluid (hCSF) enhances the growth and activity of both rodent and human brain tissue compared to artificial cerebrospinal fluid (aCSF), showing improved network functionality.
  • Experiments demonstrated that hCSF not only increased overall neuronal activity but also modified the firing patterns and interactions between specific groups of neurons within the brain slices.
  • The findings suggest that utilizing hCSF in electrophysiological studies can better replicate physiological and pathological conditions in human brain research.
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Most of our knowledge on human CNS circuitry and related disorders originates from model organisms. How well such data translate to the human CNS remains largely to be determined. Human brain slice cultures derived from neurosurgical resections may offer novel avenues to approach this translational gap.

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De novo mutations in the KCNA2 gene, encoding the voltage-gated potassium channel K1.2, have been identified to cause early-onset developmental and epileptic encephalopathies (DEE). K1.

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Virotherapy using oncolytic viruses is an upcoming therapy strategy for cancer treatment. A variety of preclinical and clinical trials have indicated that adenoviruses may be used as potent agents in the treatment of a variety of cancers, and also for the treatment of brain tumors. In these studies, it has also been shown that oncovirotherapy is safe in terms of toxicity and side effects.

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The developmental and epileptic encephalopathies (DEEs) are heterogeneous disorders with a strong genetic contribution, but the underlying genetic etiology remains unknown in a significant proportion of individuals. To explore whether statistical support for genetic etiologies can be generated on the basis of phenotypic features, we analyzed whole-exome sequencing data and phenotypic similarities by using Human Phenotype Ontology (HPO) in 314 individuals with DEEs. We identified a de novo c.

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Article Synopsis
  • * About 25% of affected individuals met the criteria for autism, and the prevalence of epilepsy varied by sex, being more common in females, with many cases responding well to treatment.
  • * Individuals with missense variants in KMT2E showed the most severe developmental issues, including treatment-resistant epilepsy and microcephaly, highlighting the need for further research to understand the effects of these variants.
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Developmental and epileptic encephalopathies (DEE) can be caused by mutations in the KCNA2 gene, coding for the voltage-gated K+ channel K1.2. This ion channel belongs to the delayed rectifier class of potassium channels and plays a role during the repolarization phase of an action potential.

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Developmental and epileptic encephalopathies (DEEs) are severe neurodevelopmental disorders often beginning in infancy or early childhood that are characterized by intractable seizures, abundant epileptiform activity on EEG, and developmental impairment or regression. CACNA1E is highly expressed in the central nervous system and encodes the α-subunit of the voltage-gated Ca2.3 channel, which conducts high voltage-activated R-type calcium currents that initiate synaptic transmission.

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Pathophysiological investigation of CNS-related diseases, such as epilepsy or neurodegenerative disorders, largely relies on histological studies on human post mortem tissue, tissue obtained by biopsy or resective surgery and on studies using disease models including animal models, heterologous expression systems or cell culture based approaches. However, in general it remains elusive to what extent results obtained in model systems can be directly translated to the human brain, calling for strategies allowing validation or even primary investigation in live human CNS tissue. In the work reported here, we prepared human organotypic slice cultures from access tissue of resective epilepsy surgery.

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Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients.

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