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Baumann, B.

Publications and source records attributed to Baumann, B..

9 recordsLinked to original sources

A mutation-agnostic and allele-specific ASO strategy demonstrates potent functional rescue and retinal preservation in RHO-linked retinitis pigmentosa

Autosomal dominant retinitis pigmentosa (adRP) caused by RHO mutations is a leading form of inherited retinal degeneration. Extensive allelic heterogeneity of RHO pathogenic variants limits the translational applicability of mutation-specific gene therapies. To address this, we developed SNARE (SNP-guided Silencing of Aberrant RHO Expression), a mutation-independent, allele-specific antisense oligonucleotide (ASO) strategy. SNARE selectively suppresses mutant RHO transcripts by targeting the common, benign c.-26A/G single-nucleotide polymorphism (SNP) as an allelic discriminator. Candidate gapmer ASOs were screened in engineered reporter lines and validated in patient-derived retinal organoids, identifying RHOligo-A as the lead c.-26A-targeting candidate. In vitro, RHOligo-A achieved robust, preferential knockdown of the target allele, improving RHO localization in retinal organoids, and demonstrated a favorable safety profile with minimal transcriptomic off-target effects and no detectable immunostimulatory activity. Subsequent validation in a novel, humanized RHOP347L/WT mouse model, achieved sustained c.-26A-linked allele-selective suppression, retinal structure preservation, and significantly restored visual function, upon a single intravitreal administration. These findings establish RHOligo-A and SNARE as a scalable, mutation-independent therapeutic platform with strong translational potential and substantial clinical reach for RHO-associated adRP.

genetics↗

Exploration of Structural Optic Nerve Changes in Mouse Models of Retinal and Neuronal Degeneration with Optical Coherence Tomography

PurposeThe optic nerve head (ONH) is a central feature of the retina, affected in many human ocular pathologies, yet it has remained underexplored in most mouse models of disease. We hypothesize that the analysis of the ONH can yield valuable insight into the phenotype of retinal diseases and that pathological changes can be detected using state-of-the-art optical coherence tomography (OCT). MethodsFour mouse models - the 5xFAD, PS19 and APP/PS1 models of Alzheimers disease (AD) as well as the SOD1 knockout mouse model - were imaged using a polarization-sensitive OCT system to investigate potential disease related changes of the ONH. 5xFAD and SOD1 animals were investigated longitudinally to study disease progression. Additionally, aging effects in wild type mice were studied. ResultsTwo different analysis methods for the segmentation of the ONH were implemented and evaluated. Longitudinal changes to the ONH in 5xFAD animals were observed, specifically an increase of ONH volume from 3 to 5 months of age followed by a strong decrease until 9 months of age. Significant differences between transgenic (tg) and non-transgenic (ntg) animals, as well as sex dependent distinctions were found. Also, for the APP/PS1 model disease related differences between ntg and tg APP/PS1 were significant. ConclusionsWe demonstrated a simple segmentation of the ONH structure based on OCT intensity images and show its potential as a preclinical biomarker in amyloid mouse models of AD.

neuroscience↗

Ultrasensitive saliva-based detection of early Alzheimer's disease biomarkers via nanoparticle-enhanced evanescent scattering microscopy

Alzheimers disease (AD) is the most common neurodegenerative disease, yet early diagnosis remains a major challenge. Current cerebrospinal fluid (CSF) assays are invasive and unsuitable for large-scale or repeated screening. Blood-based biomarkers have achieved sensitivities above 90%, but still face challenges of standardization, cost, technical complexity, and the need for sophisticated instrumentation. Saliva offers an attractive, non-invasive solution; however, the low concentrations of AD biomarkers have thus far hindered its clinical applicability. Here, we introduce a saliva-based diagnostic platform that combines Total Internal Reflection Scattering (TIRS) microscopy with antibody-functionalized metallic nanoparticles (NPs), for ultrasensitive, real-time quantification of salivary amyloid-{beta} (A{beta}) proteins. Using two established AD mouse models (APPsl and 5xFAD), we found that salivary A{beta}2 levels robustly distinguish transgenic from wild-type animals and correlate with brain amyloid deposition. Pooled and stratified analyses suggest these associations are primarily driven by the transgenic-wild-type contrast rather than linear changes within groups. Predictive modeling further confirmed diagnostic utility: in APPsl, Logistic Regression and Support Vector Machine (SVM) classifiers both achieved 92% accuracy with balanced sensitivity and specificity, while in 5xFAD, SVM reached 88% accuracy with perfect specificity. These results establish the NPs-enhanced TIRS sensor as a rapid, accurate and non-invasive tool for AD detection via saliva. By addressing a critical unmet need in neurodegenerative disease screening, this platform has strong potential to transform early diagnosis, enable timely interventions, and support biomarker-guided clinical trials. Its simplicity, speed, and scalability, make it well-suited for point-of-care diagnostics and large-scale screening initiatives. One Sentence SummaryUltrasensitive saliva test detects early Alzheimers biomarkers using nanoparticle-enhanced scattering microscopy

biochemistry↗

On the potential sources of a low-frequency sound percept only a few can hear

A small percentage of the general population reports almost constant humming or pulsing low-frequency sound percepts (LFSPs) while others in their vicinity, such as family members, often do not perceive these sounds. The origin of these LFSPs remains to be elucidated and may or may not be related to external sound sources. The underlying causes of these perceptions could also be subjective and belong to the tinnitus family, especially in cases where no external sound source sufficiently explaining the LFSP can be found. The present study puts forth two hypotheses to explain the phenomenon, based on both subjective and objective auditory phenomena: an unusually high auditory sensitivity to low-frequency sound, and hearing ones own low-frequency spontaneous otoacoustic emissions (SOAEs), sounds actively produced by the inner ear as a normal, physiological by-product of cochlear amplification. The present study employed high-resolution, low-frequency hearing threshold measurements and SOAE measurements in 28 individuals with LFSPs, and in control groups devoid of LFSPs. LFSP complainants self-reported hearing a LFSP at a median frequency of 50 Hz obtained with a frequency-matching procedure. With a few clear exceptions, complainants most often did not present unusually sensitive low-frequency hearing thresholds. Furthermore, hearing threshold fine structure was comparable to the control group. In addition, no SOAEs in the low-frequency range could be measured. Based on our results, while cases of hearing physical external sound sources are not ruled out, we suggest that a subjective tinnitus in the low-frequency range is often the reason behind hearing these LFSPs.

biophysics↗

Longitudinal investigation of spatial memory and retinal parameters in a 5xFAD model of Alzheimers disease reveals differences dependent on genotype and sex

SignificanceThe retinal phenotype of Alzheimers disease (AD) is poorly understood. The connection between spatial memory and retinal phenotype is poorly investigated. Additionally, the influence of sex on the disease in mouse models is not sufficiently clear and requires further investigation. AimTo investigate the retina and spatial memory of 5xFAD mouse models of AD by measuring retinal and behavioral parameters. ApproachA custom-built optical coherence tomography (OCT) system is used to image the retina of both eyes of 32 transgenic 5xFAD mice and 32 non-transgenic littermates over the course of 6 months (3-9 months of age) to investigate retinal parameters. The Morris Water Maze (MWM) test was performed to examine correlations between the retinal and spatial memory phenotype of the mouse model. ResultsData were acquired in the form of OCT reflectivity images and OCT angiograms as well as video recordings of the MWM test. Layer thickness and vascular density were calculated from the resulting data. Behavioral data was extracted from the videos acquired from the MWM. Total retinal and inner retinal layer thickness increased slightly over the measurement period, while outer retinal layer and retinal nerve fiber layer thickness showed no significant change. The correlation analysis between MWM and layer thickness data revelated a positive correlation between inner nuclear layer thickness and MWM test day parameters. ConclusionsOCT and MWM data revealed sex-based differences in the retinal phenotype of the 5xFAD mouse model, with changes in retinal thickness in different stages of the study and dissimilar correlations between retinal and spatial memory phenotype.

neuroscience↗

-Labeled PARP-1 PET Imaging of PSMA Targeted Alpha Particle Radiotherapy Response

MotivationThe growing interest and clinical translation of alpha particle () therapies brings with it new challenges to assess target cell engagement and to monitor therapeutic effect. Noninvasive imaging has great potential to guide -treatment and to harness the potential of these agents in the complex environment of disseminated disease. Poly(ADP) ribose polymerase 1 (PARP-1) is among the most abundantly expressed DNA repair enzymes with key roles in multiple repair pathways - such as those induced by irradiation. Materials and MethodsHere, we used a third-generation PARP1-specific radiotracer, [18F]-PARPZ, to delineate castrate resistant prostate cancer xenografts. Following treatment with the clinically applied [225Ac]-PSMA-617, positron emission tomography was performed and analyzed, along with and correlative autoradiography and histology acquired. Results[18F]-PARPZ was able to distinguish treated from control (saline) xenografts by uptake. Kinetic analysis of tracer accumulation also suggests that the localization of the agent to sites of increased PARP-1 expression is a consequence of DNA damage response. ConclusionsTogether, these data support expanded investigation of [18F]-PARPZ to facilitate clinical translation in the -therapy space.

cancer biology↗

Vitamin D Sufficiency Enhances Differentiation of Patient-Derived Prostate Epithelial Organoids

Vitamin D is an essential steroid hormone that regulates systemic calcium homeostasis and cell fate decisions, including differentiation in many cell types. The prostate gland is hormonally regulated, requiring steroids for proliferation and terminal differentiation of secretory luminal cells. Vitamin D deficiency is associated with higher risk of lethal prostate cancer with an aggressive dedifferentiated pathology, linking vitamin D sufficiency to epithelial differentiation homeostasis. To determine regulation of prostate epithelial differentiation by vitamin D status, patient-derived benign prostate epithelial organoids were maintained in vitamin D deficient (vehicle) or sufficient (10 nM 1,25-dihydroxyvitamin D) conditions and assessed by phenotype and single cell RNA sequencing. Mechanistic validation demonstrated that vitamin D sufficiency promoted organoid growth and accelerated differentiation of lineage-committed cells by inhibiting canonical Wnt activity and Wnt family member DKK3. Wnt dysregulation is a known contributor to aggressive prostate cancer, thus these findings further link vitamin D deficiency to lethal disease.

cell biology↗

Species-specific differences in the susceptibility of fungi towards the antifungal protein AFP depend on C3 saturation of glycosylceramides

AFP is an antimicrobial peptide (AMP) produced by the filamentous fungus Aspergillus giganteus and a very potent inhibitor of fungal growth without affecting the viability of bacteria, plant or mammalian cells. It targets chitin synthesis and causes plasma membrane permeabilization in many human and plant pathogenic fungi, but its exact mode of action is not known. We have recently proposed adoption of the \"damage-response framework of microbial pathogenesis\" put forward by Pirofksi and Casadevall in 1999 regarding the analysis of interactions between AMPs and microorganisms, thus, predicting that the cytotoxic capacity of a given AMP is relative and depends not only on the presence/absence of its target(s) in the host and the AMP concentration applied but also on other variables, such as microbial survival strategies. We show here using the examples of three filamentous fungi (Aspergillus niger, Aspergillus fumigatus, Fusarium graminearum) and two yeasts (Saccharomyces cerevisiae, Pichia pastoris) that the important parameters defining the AFP susceptibilities of these fungi are (i) the presence/absence of glycosylceramides, (ii) the presence/absence of {Delta}3(E)-desaturation of the fatty acid chain therein, and (iii) the (dis)ability of these fungi to respond to AFP inhibitory effects with the fortification of their cell walls via increased chitin and {beta}-(1,3)-glucan synthesis. These observations support the adoption of the damage-response framework to holistically understand the outcome of AFP inhibitory effects.\n\nImportanceOur data suggest a fundamental role of glycosylceramides in the susceptibility of fungi towards AFP. We discovered that only a minor structural difference in these molecules - the saturation level of their fatty acid chain, controlled by a 2-hydroxy fatty N-acyl-{Delta}3(E)-desaturase - is a key to understanding the inhibitory activity of AFP. As glycosylceramides are important components of fungal plasma membranes, we propose a model which links AFP-mediated inhibition of chitin synthesis in fungi with its potential to disturb plasma membrane integrity.

microbiology↗

Updating genome annotation for the microbial cell factory Aspergillus niger using gene co-expression networks

A significant challenge in our understanding of biological systems is the high number of genes with unknown function in many genomes. The fungal genus Aspergillus contains important pathogens of humans, model organisms, and microbial cell factories. Aspergillus niger is used to produce organic acids, proteins, and is a promising source of new bioactive secondary metabolites. Out of the 14,165 open reading frames predicted in the A. niger genome of only 2% have been experimentally verified and over 6,000 are hypothetical. Here we show that gene co-expression network analysis can be used to overcome this limitation. A meta-analysis of 155 transcriptomics experiments generated co-expression networks for 9,579 genes ([~]65%) of the A. niger genome. By populating this dataset with over 1,200 gene functional experiments from the genus Aspergillus and performing gene ontology enrichment, we could infer biological processes for 9,263 of A. niger genes, including 2,970 hypothetical genes. Experimental validation of selected co-expression sub-networks uncovered four transcription factors involved in secondary metabolite synthesis, which were used to activate production of multiple natural products. This study constitutes a significant step towards systems-level understanding of A. niger, and the datasets can be used to fuel discoveries of model systems, fungal pathogens, and biotechnology.

systems biology↗