348 results match your criteria: "Institute for Medical Physics and Biophysics[Affiliation]"

Noninvasive Ultra Low Intensity Light Photodynamic Treatment of Glioblastoma with Drug Augmentation: LoGlo PDT Regimen.

Brain Sci

November 2024

Neurosurgery Department-Neuro-Oncology, Instituto de Neurologia de Curitiba, Rua Jeremias Maciel Perretto, 300-Campo Comprido, Curitiba 81210-310, Brazil.

This paper presents the basis for LoGlo PDT, a new treatment for glioblastoma. Glioblastoma is currently treated with maximal safe resection, temozolomide, and ionizing irradiation. Mortality in 2024 remains over 80% within several years from diagnosis.

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The GPCR autoproteolysis inducing (GAIN) domain is an ancient protein fold ubiquitous in adhesion G protein-coupled receptors (aGPCR). It contains a tethered agonist necessary and sufficient for receptor activation. The GAIN domain is a hotspot for pathological mutations.

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structural biology with cryo-electron tomography (cryo-ET) and subtomogram averaging (StA) is evolving as a major method to understand the structure, function, and interactions of biological molecules in cells in a single experiment. Since its inception, the method has matured with some stellar highlights and with further opportunities to broaden its applications. In this short review, I want to provide a personal perspective on the developments in cryo-ET as I have seen it for the last ~20 years and outline the major steps that led to its success.

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Allopregnanolone (AlloP) is an example of neuroactive steroids (NAS), which is a potent allosteric activator of the γ-aminobutyric acid A (GABA) receptor. The mechanisms underlying the biological activity of AlloP and other NAS are only partially understood. Here, we present intrinsically fluorescent analogs of AlloP (MQ-323) and its 3β-epimer, epi-allopregnanolone (E-AlloP) (YX-11), and show, by a combination of spectroscopic and computational studies, that these analogs mimic the membrane properties of AlloP and E-AlloP very well.

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Article Synopsis
  • Live-cell imaging of cholesterol trafficking requires suitable fluorescent cholesterol analogs, but current options have significant drawbacks, such as differing properties or requiring UV excitation.
  • The study introduces two new fluorescent sterol probes that resemble cholesterol closely, enhancing their applicability for imaging.
  • One probe features visible emissions suitable for conventional microscopy, while the other proves unstable and unusable, making the first a better choice for studying sterol transport in live cells.*
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How the liver transcriptome and lipid composition influence the progression of nonalcoholic fatty liver disease to hepatocellular carcinoma in a murine model.

Biochim Biophys Acta Mol Cell Biol Lipids

January 2025

Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry (IFMPEGKC), RWTH University Hospital Aachen, 52074 Aachen, Germany. Electronic address:

The incidence of nonalcoholic fatty liver disease (NAFLD) has been steadily increasing in Western society in recent years and has been recognized as a risk factor for the development of hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying the progression from NAFLD to HCC are still unclear, despite the use of suitable mouse models. To identify the transcriptional and lipid profiles of livers from mice with NAFLD-HCC, we induced both NAFLD and NAFLD-HCC pathologies in C57BL/6J mice and performed RNA-sequencing (RNA-seq) and targeted lipidomic analysis.

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Cellular membranes exhibit a huge diversity of lipids and membrane proteins that differ in their properties and chemical structure. Cells organize these molecules into distinct membrane compartments characterized by specific lipid profiles and hydrophobic thicknesses of the respective domains. If a hydrophobic mismatch occurs between a membrane protein and the surrounding lipids, there can be functional consequences such as reduced protein activity.

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Article Synopsis
  • T-2 toxin, a highly toxic trichothecene mycotoxin, was studied using high-resolution magic-angle spinning nuclear magnetic resonance (HRMAS NMR) and zebrafish embryos to explore its toxicity mechanisms.
  • The study found that T-2 exposure resulted in lethality at around 105 ppb and influenced the production of reactive oxygen species (ROS), causing varied ROS levels in different organs.
  • Metabolic profiling indicated significant disturbances in detoxification processes, membrane phospholipids, mitochondrial energy metabolism, and glucose metabolism, leading to a comprehensive understanding of T-2 toxicity for health implications.
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Acyl-coenzyme A: cholesterol acyltransferases are enzymes which are involved in the homeostasis of cholesterol. Impaired enzyme activity is associated with the occurrence of various diseases like Alzheimer's disease, atherosclerosis, and cancers. At present, mitotane is the only inhibitor of this class of enzymes in clinical use for the treatment of adrenocortical carcinoma but associated with common and severe adverse effects.

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Structural basis of α-latrotoxin transition to a cation-selective pore.

Nat Commun

October 2024

Institute for Medical Physics and Biophysics, University Münster, Münster, Germany.

Article Synopsis
  • The black widow spider's venom contains a range of neurotoxic latrotoxins (LTXs), with the most significant one being α-LTX, which affects vertebrates by disrupting neurotransmitter release at nerve terminals.
  • α-LTX is composed of multiple structural domains and functions by forming tetramers that create calcium-conductive pores in the presynaptic membrane, although the exact mechanism is not fully understood.
  • New cryo-electron microscopy (cryoEM) studies reveal structural changes in α-LTX that allow it to insert into membranes and form cation-permeable channels, providing insights that could lead to new medical and technological advancements.
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Oxygen-tolerant [NiFe] hydrogenases are valuable blueprints for the activation and evolution of molecular hydrogen under application-relevant conditions. Vibrational spectroscopic techniques play a key role in the investigation of these metalloenzymes. For instance, resonance Raman spectroscopy has been introduced as a site-selective approach for probing metal-ligand coordinates of the [NiFe] active site and FeS clusters.

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Under physiological conditions, proteins continuously undergo structural fluctuations on different timescales. Some conformations are only sparsely populated, but still play a key role in protein function. Thus, meaningful structure-function frameworks must include structural ensembles rather than only the most populated protein conformations.

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(Chemical) Roles of HOCl in Rheumatic Diseases.

Antioxidants (Basel)

July 2024

Institute for Medical Physics and Biophysics, Medical Faculty, Leipzig University, 04103 Leipzig, Germany.

Chronic rheumatic diseases such as rheumatoid arthritis (RA) are characterized by a dysregulated immune response and persistent inflammation. The large number of neutrophilic granulocytes in the synovial fluid (SF) from RA patients leads to elevated enzyme activities, for example, from myeloperoxidase (MPO) and elastase. Hypochlorous acid (HOCl), as the most important MPO-derived product, is a strong reactive oxygen species (ROS) and known to be involved in the processes of cartilage destruction (particularly regarding the glycosaminoglycans).

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In this work, we explored how the amount of cholesterol in the lipid membrane composed of phosphatidylcholine (POPC) or phosphatidylglycerol (POPG) affects the interaction with 1-dodecyl-3-methylimidazolium bromide ([CMIM]Br) ionic liquids using various biophysical techniques. On interacting with the membrane, [CMIM]Br leads to enhanced membrane permeability and induces membrane fusion, leading to an increase in vesicle size. The H-based solid-state NMR investigations of cholesterol-containing lipid membranes reveal that [CMIM]Br decreases the lipid chain order parameters and counteracts the lipid condensation effect of cholesterol to some extent.

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Article Synopsis
  • The MutationExplorer webserver helps scientists understand how changes in a protein's sequence can affect its structure and function by showing 3D models.
  • Users can enter specific mutations and see how the protein's energy changes and how it might behave.
  • The tool allows for easy uploads of large data, making it quick for researchers to see how different variations in proteins influence their properties.
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Side-chain motions play an important role in understanding protein structure, dynamics, protein-protein, and protein-ligand interactions. However, our understanding of protein side-chain dynamics is currently limited by the lack of analytical tools. Here, we present a novel analytical framework employing experimental nuclear magnetic resonance (NMR) relaxation measurements at atomic resolution combined with molecular dynamics (MD) simulation to characterize with a high level of detail the methyl side-chain dynamics in insoluble protein assemblies, using amyloid fibrils formed by the prion HET-s.

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Unraveling motion in proteins by combining NMR relaxometry and molecular dynamics simulations: A case study on ubiquitin.

J Chem Phys

March 2024

Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland.

Nuclear magnetic resonance (NMR) relaxation experiments shine light onto the dynamics of molecular systems in the picosecond to millisecond timescales. As these methods cannot provide an atomically resolved view of the motion of atoms, functional groups, or domains giving rise to such signals, relaxation techniques have been combined with molecular dynamics (MD) simulations to obtain mechanistic descriptions and gain insights into the functional role of side chain or domain motion. In this work, we present a comparison of five computational methods that permit the joint analysis of MD simulations and NMR relaxation experiments.

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The possible effects of mutations on stability and function of a protein can only be understood in the context of protein 3D structure. The MutationExplorer webserver maps sequence changes onto protein structures and allows users to study variation by inputting sequence changes. As the user enters variants, the 3D model evolves, and estimated changes in energy are highlighted.

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Known for their high stability and surfactant properties, per- and polyfluoroalkyl substances (PFAS) have been widely used in a range of manufactured products. Despite being largely phased out due to concerns regarding their persistence, bioaccumulation, and toxicity, legacy PFAS such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid continue to persist at high levels in the environment, posing risks to aquatic organisms. We used high-resolution magic angle spinning nuclear magnetic resonance spectroscopy in intact zebrafish (Danio rerio) embryos to investigate the metabolic pathways altered by PFOS both before and after hatching (i.

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The molecular mechanisms underlying the transition from nonalcoholic fatty liver disease (NAFLD) to hepatocellular carcinoma (HCC) are incompletely understood. During the development of NAFLD, Perilipin 5 (PLIN5) can regulate lipid metabolism by suppressing lipolysis and preventing lipotoxicity. Other reports suggest that the lack of PLIN5 decreases hepatic injury, indicating a protective role in NAFLD pathology.

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Amyloid β (Aβ) is a hallmark protein of Alzheimer's disease. One physiologically important Aβ variant is formed by initial N-terminal truncation at a glutamic acid position (either E or E), which is subsequently cyclized to a pyroglutamate (either pE or pE). Both forms have been found in high concentrations in the core of amyloid plaques and are likely of high importance in the pathology of Alzheimer's disease.

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The adhesion G-protein-coupled receptor mayo/CG11318 controls midgut development in Drosophila.

Cell Rep

January 2024

Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, 04103 Leipzig, Germany; Institute of Biology, Faculty of Life Sciences, Leipzig University, Talstraße 33, 04103 Leipzig, Germany; Comprehensive Cancer Center Central Germany (CCCG), Germany. Electronic address:

Adhesion G-protein-coupled receptors (aGPCRs) form a large family of cell surface molecules with versatile tasks in organ development. Many aGPCRs still await their functional and pharmacological deorphanization. Here, we characterized the orphan aGPCR CG11318/mayo of Drosophila melanogaster and found it expressed in specific regions of the gastrointestinal canal and anal plates, epithelial specializations that control ion homeostasis.

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From Oxidized Fatty Acids to Dimeric Species: In Vivo Relevance, Generation and Methods of Analysis.

Molecules

November 2023

Institute for Medical Physics and Biophysics, Faculty of Medicine, Leipzig University, Härtelstr. 16-18, D-04107 Leipzig, Germany.

The occurrence of free fatty acids (FFAs) and the generation of reactive oxygen species (ROS) such as hydroxyl radicals (HO) or hypochlorous acid (HOCl) is characteristic of inflammatory diseases, for instance, rheumatoid arthritis. Unsaturated fatty acids react with ROS yielding a variety of important products such as peroxides and chlorohydrins as primary and chain-shortened compounds (e.g.

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A comprehensive understanding of how dietary components impact immunoregulatory gene expression in adipose tissue (AT) and liver, and their respective contributions to metabolic health in mice, remains limited. The current study aimed to investigate the metabolic consequences of a high-sucrose diet (HSD) and a high-fat diet (HFD) in female mice with a focus on differential lipid- and sucrose-induced changes in immunoregulatory gene expression in AT and liver. Female C57BL/6 J mice were fed a purified and macronutrient matched high fat, high sugar, or control diets for 12 weeks.

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NMR spectroscopy techniques can provide important information about protein-ligand interactions. Here we tested an NMR approach which relies on the measurement of paramagnetic relaxation enhancements (PREs) arising from analogous cationic, anionic or neutral soluble nitroxide molecules, which distribute around the protein-ligand complex depending on near-surface electrostatic potentials. We applied this approach to two protein-ligand systems, interleukin-8 interacting with highly charged glycosaminoglycans and the SH2 domain of Grb2 interacting with less charged phospho-tyrosine tripeptides.

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