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bioRxiv2026

Intra-slide calibration technology improves immunohistochemical harmonization within and between anatomic pathology laboratories

The reproducibility of immunohistochemistry in tumor tissue analysis across reference labs remains a persistent challenge. We tested the extent to which an intra-slide calibration technology mitigated discprepencies in inter-laboratory assays of p53 immunohistochemical (IHC) reactions in brain biopsies of glioblastoma (GB), IDH-wildtype. Intra-slide calibration technologies apply a 0-100% concentration scale incorporating primary surrogate and secondary antibodies to generate a standardized curve for DAB precipitation. IHC from GB samples was performed independently by pathology departments from two different hospital laboratories and were digitalized at 40x magnification using Aperio Image Scope software. Feature extraction, including intensity and texture parameters was performed using the EBImage package in R, followed by UMAP dimensionality reduction and DBSCAN clustering analysis. Our results show significant differences in intensity and texture clustering patterns between laboratory tissue samples and intra-slide calibration technology ruler caused by the different laboratories. Intra-slide calibration technology coupled with polynomial regression analysis improved ~90% the data harmonization. Our findings demonstrate a key role for computational pathology using intra-slide calibration technology to enable intra-laboratory consistency and inter-laboratory reproducibility. These advances strengthen the reproducibility of diagnostic assessments and support more objective, data-driven decision-making in neuro-oncology.

bioinformatics↗

bioRxiv2019

Extent of N-terminus exposure by altered long-range interactions of monomeric alpha-synuclein determines its aggregation propensity

As an intrinsically disordered protein, monomeric alpha synuclein (aSyn) constantly reconfigures and probes the conformational space. Long-range interactions across the protein maintain its solubility and mediate this dynamic flexibility, but also provide residual structure. Certain conformations lead to aggregation prone and non-aggregation prone intermediates, but identifying these within the dynamic ensemble of monomeric conformations is difficult. Herein, we used the biologically relevant calcium ion to investigate the conformation of monomeric aSyn in relation to its aggregation propensity. By using calcium to perturb the conformational ensemble, we observe differences in structure and intra-molecular dynamics between two aSyn C-terminal variants, D121A and pS129, and the aSyn familial disease mutants, A30P, E46K, H50Q, G51D, A53T and A53E, compared to wild-type (WT) aSyn. We observe that the more exposed the N-terminus and the beginning of the NAC region are, the more aggregation prone monomeric aSyn conformations become. N-terminus exposure occurs upon release of C-terminus interactions when calcium binds, but the level of exposure is specific to the aSyn mutation present. There was no correlation between single charge alterations, calcium affinity, or the number of ions bound on aSyns aggregation propensity, indicating that sequence or post-translation modification (PTM)-specific conformational differences between the N- and C-termini and the specific local environment mediate aggregation propensity instead. Understanding aggregation prone conformations of monomeric aSyn and the environmental conditions they form under will allow us to design new therapeutics targeted to the monomeric protein, to stabilise aSyn in non-aggregation prone conformations, by either preserving long-range interactions between the N- and C-termini or by protecting the N-terminus from exposure.

biophysics↗