Biology subjects

Weimer, R.

Publications and source records attributed to Weimer, R..

3 recordsLinked to original sources

bioRxiv2025

Cellular-resolution OCT reveals layer-specific retinal mosaics and ganglion cell degeneration in mouse retina in vivo

Cellular-resolution retinal imaging in preclinical mouse models is limited by optical aberrations and speckle noise that prevent visualization of individual cells. We developed a wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) platform that addresses these challenges by combining real-time aberration correction with multi-volume averaging. This integrated approach enhanced image contrast by 61% and sharpness by 55%, while averaging 50 volumes effectively reduced speckle noise. Our system enabled visualization of individual cells across all major retinal layers and the retinal pigment epithelium in living mice. Immunohistochemical validation within the retinal ganglion cell (RGC) layer confirmed that 95% of optically detected cells corresponded to actual RGCs, confirming cell-type specificity. We demonstrated the methods translational potential by tracking RGC loss following optic nerve injury. The platform detected significant cell degeneration within three days post-injury, earlier than traditional thickness-based methods, quantifying a decline from 4,407 to 1,683 cells/mm2 (62% loss) over seven days. These results establish WSAO-OCT as an effective, non-invasive tool for cellular-level investigation of retinal pathologies, suitable for longitudinal monitoring and therapeutic evaluations in preclinical models.

bioengineering↗

bioRxiv2024

Imaging synaptic density in ageing and Alzheimer's Disease with -SynVesT-1

Monitoring synaptic injury in neurodegenerative diseases may provide new insights into the evolution of the degenerative process as well as a potential mechanism to target for preservation of function. Synaptic density imaging with PET is a relatively new approach to this issue. However, there are remaining questions about technical approaches to data analysis including reference region selection, and how specific phenotypic presentations and symptoms of Alzheimers Disease (AD) are reflected in alterations in synaptic density. MethodsUsing an SV2A PET ligand radiolabeled with the 18F isotope ([18F]-SynVesT-1) we performed sensitivity analyses to determine the optimal reference tissue modelling approach to derive whole brain ratio images. Using these whole brain images from a sample of young adults, older adults, and patients with varied phenotypic presentations of AD we then contrast regional SV2A density and in vivo AD biomarkers. ResultReference tissue optimisation concluded that a cerebellar grey matter reference region is best for deriving whole brain ratio images. Using these whole brain ratio images, we find a strong inverse association between [18F]-SynVesT-1 PET uptake and amyloid beta and tau PET deposition. Finally, we find that individuals with lower temporal grey matter volume but higher temporal [18F]-SynVesT-1 PET uptake show preserved performance on the MMSE. Conclusions[18F]-SynVesT-1 PET shows a close association with in vivo AD pathology and preserved SV2A density may be a possible marker for resilience to neurodegeneration.

neuroscience↗

bioRxiv2018

Disruption of IRE1α through its Kinase Domain Attenuates Multiple Myeloma

Multiple myeloma (MM) arises from malignant immunoglobulin-secreting plasma cells and remains an incurable, often lethal disease despite recent therapeutic advances. The unfolded-protein response sensor IRE1 supports protein secretion by deploying a kinase-endoribonuclease module to activate the transcription factor XBP1s. MM cells may coopt the IRE1-XBP1s pathway; however, the validity of IRE1 as a potential MM therapeutic target is controversial. Here we show that genetic disruption of IRE1 or XBP1s, or pharmacologic IRE1 kinase inhibition, attenuated subcutaneous or orthometastatic growth of MM tumors in mice, and augmented efficacy of two well-established frontline antimyeloma agents, bortezomib or lenalidomide. Mechanistically, IRE1 perturbation inhibited expression of key components of the ER-associated degradation machinery, as well as cytokines and chemokines known to promote MM growth. Selective IRE1 kinase inhibition reduced viability of CD138+ plasma cells while sparing CD138- cells from bone marrow of newly diagnosed MM patients or patients whose disease relapsed after 1 - 4 lines of treatment in both US- and EU-based cohorts. IRE1 inhibition preserved survival and glucose-induced insulin secretion by pancreatic microislets. Together, these results establish a strong therapeutic rationale for targeting IRE1 with kinase-based small-molecule inhibitors in MM.\n\nSignificance statementMultiple myeloma (MM) is a lethal malignancy of plasma cells. MM cells have an expanded endoplasmic reticulum (ER) that is constantly under stress due to immunoglobulin hyperproduction. The ER-resident sensor IRE1 mitigates ER stress by expanding the ERs protein-folding capacity while supporting proteasomal degradation of misfolded ER proteins. IRE1 elaborates these functions by deploying its cytoplasmic kinase-RNase module to activate the transcription factor XBP1s. The validity of IRE1 as a potential therapeutic target in MM has been questioned. Using genetic and pharmacologic disruption in vitro and in vivo, we demonstrate that the IRE1-XBP1s pathway plays a critical role in MM growth. We further show that IRE1s kinase domain is an effective and safe potential small-molecule target for MM therapy.

cancer biology↗