👤 Anand Sridharan

Samples often have to be frozen and thawed prior to analysis for immunoassays. Reliable cytokine measurement from small-volume plasma and serum samples is critical for biomarker research and clinical studies. However, repeated freeze-thaw (F-T) cycles may alter analyte stability, introducing error and reducing reproducibility. Standard statistical methods often overlook donor-to-donor and matrix variability, leading to overestimation of F-T effects. We measured 80 cytokines across three donors, three matrices (EDTA-plasma (PL-EDTA), heparin-plasms (PL-heparin), serum), and four F-T cycles using an 80-plex Luminex immunoassay. Linear mixed-effects modeling was applied to partition donor, matrix, and F-T contributions, while principal component analysis (PCA) summarized global variance. Cytokines were classified as stable, decreasing, or matrix-specific based on within-matrix slopes and matrix×cycle interactions. Stability was defined as the absence of a statistically significant per-cycle change (p ≥ 0.05) within all matrices, corresponding to changes smaller than typical assay imprecision (CV%). PCA revealed that donor and matrix were the dominant sources of global variation, whereas F-T cycles contributed minimally. Most cytokines remained stable (no significant within-matrix slope across cycles; p ≥ 0.05 in all matrices) across four cycles, with only a minority showing monotonic decreases. Matrix context strongly influenced F-T effects: PL-heparin displayed both increases and decreases, PL-EDTA was largely stable, and serum showed decreases without increases. Representative analytes highlighted the three categories: IL17E/IL25 and IL27 decreased modestly across matrices, chemokines such as 6CKINE/CCL21 remained stable, and analytes like SDF1A + B/CXCL12 showed matrix-specific increases. Freeze-thaw cycling contributes far less to cytokine variability than donor or matrix effects. Most cytokines are robust across four cycles, and when F-T sensitivity occurs, it is largely matrix-dependent. These results provide evidence-based guidance for sample handling and highlight the importance of modeling donor and matrix effects in biomarker studies. Show less

The 17q21.31 locus in humans harbors several complex structural haplotypes including a ~970kb inversion. Different inversion haplotypes have been associated with susceptibility to microdeletions causing Koolen-de Vries syndrome and variation in fecundity and recombination rates. Here, using 210 haplotype-resolved human genome assemblies and pangenome graph-based approaches we characterize 11 distinct structural haplotypes, several of which have not been previously described. Extending our analyses to a set of haplotype-resolved great-ape genomes, we characterize the structure of an independent inversion in chimpanzees which extends an additional 650kb, encompasses 5 additional genes, and is ~2 million years younger than the human inversion. We further determine that gorillas exhibit an independent duplication of the Show less

Background & objectives Central TB division facilitated development of a line probe assay (LPA) artificial intelligence (AI) tool. The tool was developed, trained, and validated for performance by collecting more than 18,000 LPA strips across culture and drug susceptibility Testing (C&DST) laboratories. The Indian Council of Medical Research (ICMR)-National Institute for Research in Tuberculosis (NIRT) evaluated the LPAAI tool independently. The objective was to establish and verify an AI-driven system for automatically interpreting LPA strips, which are employed in tuberculosis drug resistance screening, to improve accuracy, consistency, and scalability across diverse laboratory settings. Methods The AI system integrates faster regions convolutional neural network (FR-CNN) for strip detection, detection transformer (DETR) for band localisation, and a hierarchical neural network (HNN) for classification of bands, loci, and drug labels. Independent validation was conducted by ICMR-NIRT using 2810 first-line (FL)-LPA and 241 reflex second-line (SL-LPA) across ten intermediate reference laboratories (IRLs). Results AI comparative models demonstrated an accuracy range of 92-100 per cent, with sensitivity between 80-100 per cent and specificity from 86-100 per cent for the tub, rpoB, katG, InhA, gyrA/gyrB,rrs, and eisgenes. The overall F1 score varies from 0.81 to 1.00, indicating perfect precision and recall. Interpretation & conclusions This AI system offers a novel, modular architecture capable of expert-level interpretation of LPA strips. The AI tool performs at par with expert readers and offers a reliable, scalable solution for LPA interpretation.AI tool adoption can reduce interpretation time, enhance result uniformity, and improve treatment delivery across India's TB programme, supporting national goals for TB elimination. Show less

Integration of human genomics and other omics across different ancestries provides novel, affordable, and systematic approach for target identification. We used Mendelian randomization approaches to unravel causal associations between 2,940 circulating proteins and 19 CVD. We found 218 proteins that impacted risk of one or more CVDs through forward MR (106 and 182 using cis-pQTLs only and cis- + trans-pQTLs, respectively), among which 107 were previously reported as associated with CVD or CVD-related traits. There were 102 proteins replicated (FDR < 5%, 53 with cis-pQTLs only and 88 with cis- + trans-pQTLs) using the FinnGen Olink data. BTN3A2 was highlighted as a novel candidate gene for ischemic stroke, suggesting a crosstalk between immune modulation and stroke pathogenesis. Single cell integration prioritized PAM for stable angina pectoris and ventricular arrhythmia and LPL for peripheral artery disease, whose transcriptional expressions were enriched in cardiomyocytes. Forward and reverse MR found largely non-overlapping proteins (only 2 overlapped: LGALS4 and MMP12), suggesting distinct proteomic causes and consequences of CVD. Our study provides human genetics-based evidence of novel candidate genes, a foundational step towards full-scale causal human biology-based drug discovery for CVD. Show less

Histone 3 lysine 79 methylation (H3K79me) is enriched on gene bodies proportional to gene expression levels and serves as a strong barrier for the reprogramming of somatic cells to induced pluripotent stem cells (iPSCs). DOT1L is the sole histone methyltransferase that deposits all three orders-mono (me1), di (me2), and tri (me3) methylation-at H3K79. Here, we leverage genetic and chemical approaches to parse the specific functions of orders of H3K79me in maintaining cell identity. DOT1L interacts with AF10 (Mllt10), which recognizes unmodified H3K27 and boosts H3K79me2/3 methylation. AF10 deletion evicts H3K79me2/3 and reorganizes H3K79me1 to the transcription start site to facilitate iPSC formation in the absence of steady-state transcriptional changes. Instead, AF10 loss redistributes RNA polymerase II to a uniquely pluripotent pattern at highly expressed, rapidly transcribed housekeeping genes. Taken together, we reveal a specific mechanism for H3K79me2/3 located at the gene body in reinforcing cell identity. Show less

The heterochromatin protein 1 (HP1) family is involved in various functions with maintenance of chromatin structure. During murine somatic cell reprogramming, we find that early depletion of HP1γ reduces the generation of induced pluripotent stem cells, while late depletion enhances the process, with a concomitant change from a centromeric to nucleoplasmic localization and elongation-associated histone H3.3 enrichment. Depletion of heterochromatin anchoring protein SENP7 increased reprogramming efficiency to a similar extent as HP1γ, indicating the importance of HP1γ release from chromatin for pluripotency acquisition. HP1γ interacted with OCT4 and DPPA4 in HP1α and HP1β knockouts and in H3K9 methylation depleted H3K9M embryonic stem cell (ESC) lines. HP1α and HP1γ complexes in ESCs differed in association with histones, the histone chaperone CAF1 complex, and specific components of chromatin-modifying complexes such as DPY30, implying distinct functional contributions. Taken together, our results reveal the complex contribution of the HP1 proteins to pluripotency. Show less