Biology subjects

Leitgeb, R.

Publications and source records attributed to Leitgeb, R..

5 recordsLinked to original sources

bioRxiv2025

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↗

bioRxiv2025

A functional amyloid matrix underpins the PDIM-architected corded superstructure of the Mycobacterium tuberculosis biofilm

Bacterial biofilms generate collective properties that cannot be explained by individual cells alone. Yet the structural principles that organize these communities and their relationship to drug tolerance remain poorly understood, including in major human pathogens such as Mycobacterium tuberculosis (Mtb). Here we show that submerged Mtb biofilms form organized multicellular architectures in which bacterial cords are integrated with a composite extracellular matrix. The virulence lipid phthiocerol dimycocerosate (PDIM) governs the higher-order organization of cords, proteinaceous matrix interactions support cohesion and attachment, an amyloid-like component contributes to biofilm integrity and establishment, and the ESX-1 secretion system increases matrix biochemical complexity. Biofilm growth conferred antibiotic tolerance across genetic backgrounds, while PDIM-dependent organization provided additional protection against first-line anti-tuberculosis drugs, most clearly isoniazid. Targeting amyloid assembly with epigallocatechin gallate impaired biofilm establishment without inhibiting planktonic growth. Together, these findings establish a cording-centred framework linking bacterial surface composition, cellular organization and extracellular matrix assembly to antibiotic tolerance, and show how resolving higher-order biofilm architecture can reveal processes amenable to chemical perturbation.

microbiology↗

bioRxiv2025

In Vivo Network-Level Cerebrovascular Mapping Reveals the Impact of Flow Topology on Capillary Stalls After Stroke

Cerebral microvasculature is essential for brain function, but how flow and large-scale connectivity contribute to its resilience or failure remains poorly understood. To address this, we developed OMNIMap, a framework for mesoscale in vivo mapping of functional microvascular networks, capturing flow dynamics and connectivity across thousands of capillaries. OMNIMap integrates extended-focus optical coherence microscopy and learning-based segmentation with global vessel-graph optimization to resolve artery-vein classification and branching order, linking capillary flow and stalls to broader network context. Applied to over 40,000 capillaries in the mouse cortex before and after ischemic stroke, we observe heterogeneous vulnerability patterns: while most capillaries stall or reduce flow after arterial occlusion, some experience accelerated flow. Further analysis revealed that stall-prone flow topology subtypes were less prevalent than their robust counterparts. Notably, the overall distribution of these subtypes remains largely preserved after stroke, revealing a previously unrecognized, system-level organizing principle that alleviates the impact of individual capillary stalls to maintain network-level perfusion.

neuroscience↗

bioRxiv2024

Bessel Beam Optical Coherence Microscopy Enables Multiscale Assessment of Cerebrovascular Network Morphology and Function

Understanding the morphology and function of large-scale cerebrovascular networks is crucial for studying brain health and disease. However, reconciling the demands for imaging on a broad scale with the precision of high-resolution volumetric microscopy has been a persistent challenge. In this study, we introduce Bessel beam optical coherence microscopy with an extended focus to capture the full cortical vascular hierarchy in mice over 1000 x 1000 x 360 m3 field-of-view at capillary level resolution. The post-processing pipeline leverages a supervised deep learning approach for precise 3D segmentation of high-resolution angiograms, hence permitting reliable examination of microvascular structures at multiple spatial scales. Coupled with high-sensitivity Doppler optical coherence tomography, our method enables the computation of both axial and transverse blood velocity components as well as vessel-specific blood flow direction, facilitating a detailed assessment of morpho-functional characteristics across all vessel dimensions. Through graph-based analysis, we deliver insights into vascular connectivity, all the way from individual capillaries to broader network interactions, a task traditionally challenging for in vivo studies. The new imaging and analysis framework extends the frontiers of research into cerebrovascular function and neurovascular pathologies.

bioengineering↗

bioRxiv2023

Ultrasound-Induced Reorientation for Multi-Angle Optical Coherence Tomography

Organoid and spheroid technology have recently provided great insights into oncology, developmental biology as well as personalized medicine. Among the methods to optically monitor the structural and functional organization of such samples, optical coherence tomography (OCT) has emerged as an excellent, label-free approach. Mature organoids, however, are often too opaque for OCT due to regions of strong attenuation. This leads to severe artifacts and reduced morphological tissue information in the reconstruction, since the far-side of the specimen is not reachable. Access to multi-angle views of OCT is therefore highly desirable. This aligns with another problem affecting certain goals of organoid research: The sample needs to be embedded in a growth scaffold such as Matrigel, whereas freely floating objects would not suffer from confinement and be more easily accessible for mechanical or chemical probing. Here we present ULTrasound-Induced reorientation for Multi-Angle-OCT (ULTIMA-OCT), a solution overcoming these limitations. By inserting a small 3D-printed acoustic trap to a spectral-domain OCT system, acoustic actuation enables contact-free levitation and finely tunable stepwise reorientation of samples such as zebrafish larvae and tumor spheroids, in a controlled and reproducible manner. This enables tomographic reconstruction of (sub-)mm samples with enhanced penetration depth and reduced attenuation artifacts, by means of a model-based algorithm we developed. We show that this approach is able to fuse the diverse multi-angle OCT volumes for a joint recovery of 3D-reconstruction of reflectivity, attenuation, refractive index and position registration for zebrafish larvae. We believe that our approach represents a powerful enabling tool for developmental biology and organoid research.

bioengineering↗