Biology subjects

Nguyen, S. T.

Publications and source records attributed to Nguyen, S. T..

4 recordsLinked to original sources

bioRxiv2024

Supervised non-negative matrix factorization on cell-free DNA fragmentomic features enhances early cancer detection

BackgroundCell-free circulating DNA (cfDNA) fragments exhibit non-random patterns in their length (FLEN), end-motif (EM), and distance to nucleosome position (ND). While these cfDNA features have shown promise as inputs for machine learning and deep learning models in early cancer detection, most studies utilize them as raw inputs, overlooking the potential benefits of pre-processing to extract cancer-specific features. This study aims to enhance cancer detection accuracy by developing a novel approach to feature extraction from cfDNA fragmentomics. MethodsWe implemented a supervised non-negative matrix factorization (SNMF) algorithm to generate embedding vectors capturing cancer-specific signals within cfDNA fragmentomic features. These embeddings served as input for a machine learning model to classify cancer patients from healthy individuals. ResultsWe validated our framework using two datasets: an in-house cohort of 431 cancer patients and 442 healthy individuals (dataset 1), and a published cohort comprising 90 hepatocellular carcinoma (HCC) patients and 103 individuals with cirrhosis or hepatitis B (dataset 2). In dataset 1, we achieved an AUC of 94% in pan-cancer detection. In dataset 2, our framework achieved an AUC of 100% for HCC vs healthy classification, 99% for HCC vs non-HCC patients classification, and 96% for identifying HCC patients among a mixed group of non-HCC patients and healthy donors. ConclusionThis study demonstrates the efficiency of SNMF-transformed features in improving both pan-cancer detection and specific HCC detection. Our approach offers a significant advancement in leveraging cfDNA fragmentomics for early cancer detection, potentially enhancing diagnostic accuracy in clinical settings.

bioinformatics↗

bioRxiv2024

Physiologic Regulation of Lipid Oxidation and Ferroptosis By Vitamin E, High-Density Lipoprotein, and Scavenger Receptor Class B Type 1

Ferroptosis is a form of cell death caused by oxidative (-OOH) damage to phospholipids (PL) that comprise the cell membrane. Understanding mechanisms of ferroptosis is important because of the role it plays in human disease, including cancer and neurodegeneration. Previous work has focused on the intracellular antioxidant enzyme glutathione peroxidase 4 (GPx4), which detoxifies PL-peroxides (PL-OOH) and prevents ferroptosis. Studies also show that alpha-tocopherol (-toc), the active form of Vitamin E, is an exogenous lipophilic antioxidant that inhibits ferroptosis in cancer cells in vitro and in neurons and hematopoietic stem cells in vivo. The mechanisms by which -toc engages cells to manipulate PL redox balance and ferroptosis are unknown. Lipoproteins, like high- and low-density lipoproteins (HDL and LDL), carry -toc in the circulation, which compelled our investigation of their role in -toc delivery and ferroptosis. Using cancer and neuronal cell models, here we show that lipoproteins, particularly HDL, deliver -toc by binding the cell membrane receptor scavenger receptor class B type 1 (SR-B1) to prevent ferroptosis. Additionally, we synthesized SR-B1 targeted HDL-like particles that contained -toc to validate data obtained with native lipoproteins. We reveal here a tunable cellular redox axis whereby native and synthetic HDLs containing -toc target SR-B1 to reduce PL-OOH and prevent ferroptosis.

cell biology↗

bioRxiv2020

Prediction of novel components of bacterial ribosomes by crowd-sourced analysis of RNA sequencing data

Bacterial resistance to antibiotics is a growing problem that is projected to cause more deaths than cancer in 2050. Consequently, novel antibiotics are urgently needed. Since more than half of the available antibiotics target the bacterial ribosomes, proteins that are involved in protein synthesis are thus prime targets for the development of novel antibiotics. However, experimental identification of these potential antibiotic target proteins can be labor-intensive and challenging, as these proteins are likely to be poorly characterized and specific to few bacteria. In order to identify these novel proteins, we established a Large-Scale Transcriptomic Analysis Pipeline in Crowd (LSTrAP-Crowd), where 285 individuals processed 26 terabytes of RNA-sequencing data of the 17 most notorious bacterial pathogens. In total, the crowd processed 26,269 RNA-seq experiments and used the data to construct gene co-expression networks, which were used to identify more than a hundred uncharacterized genes that were transcriptionally associated with protein synthesis. We provide the identity of these genes together with the processed gene expression data. The data can be used to identify other vulnerabilities or bacteria, while our approach demonstrates how the processing of gene expression data can be easily crowdsourced.

bioinformatics↗

bioRxiv2020

Plasmidome analysis of carbapenem-resistant Enterobacteriaceae isolated in Vietnam

Carbapenem-resistant Enterobacterales (CRE) represent a serious threat to public health due to the lack of treatment and high mortality. The rate of antimicrobial resistance of Enterobacterales isolates to major antimicrobials, including carbapenems, is much higher in Vietnam than in Western countries, but the reasons remain unknown due to the lack of genomic epidemiology research. A previous study suggested that carbapenem resistance genes, such as the carbapenemase gene blaNDM, spread via plasmids among Enterobacterales in Vietnam. In this study, we characterized blaNDM-carrying plasmids in Enterobacterales isolated in Vietnam, and identified several possible cases of horizontal transfer of plasmids both within and among species of bacteria. Twenty-five carbapenem-nonsusceptible isolates from a medical institution in Hanoi were sequenced on Illumina short-read sequencers, and 13 blaNDM-positive isolates, including isolates of Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Morganella morganii, and Proteus mirabilis, were further sequenced on an Oxford Nanopore Technologies long-read sequencer to obtain complete plasmid sequences. Almost identical 73 kb IncFII(pSE11)::IncN hybrid plasmids carrying blaNDM-1 were found in a P. mirabilis isolate and an M. morganii isolate. A 112 kb IncFII(pRSB107)::IncN hybrid plasmid carrying blaNDM-1 in an E. coli isolate had partially identical sequences with a 39 kb IncR plasmid carrying blaNDM-1 and an 88 kb IncFII(pHN7A8)::IncN hybrid plasmid in a C. freundii isolate. 148-149 kb IncFIA(Hl1)::IncA/C2 plasmids and 75-76 kb IncFII(Yp) plasmids, both carrying blaNDM-1 were shared among three sequence type 11 (ST11) isolates and three ST395 isolates of K. pneumoniae, respectively. Most of the plasmids co-carried genes conferring resistance to clinically relevant antimicrobials, including third-generation cephalosporins, aminoglycosides, and fluoroquinolones, in addition to blaNDM-1. These results provide insight into the genetic basis of CRE in Vietnam, and could help control nosocomial infections.

microbiology↗