Publications by authors named "Sang-Ho Kwon"

In the human brain, the dorsal anterior cingulate cortex (dACC) plays key roles in various components of cognitive control, and is particularly relevant for reward processing and conflict monitoring. The dACC regulates expression of fear and pain, and its dysfunction is implicated in a number of neuropsychiatric disorders. Compared to more recently specialized neocortical areas, such as the dorsolateral prefrontal cortex (dlPFC), the dACC is evolutionarily older.

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Cell types in the hippocampus with unique morphology, physiology and connectivity serve specialized functions associated with cognition and mood. These cell types are spatially organized, necessitating molecular profiling strategies that retain cytoarchitectural organization. Here we generated spatially-resolved transcriptomics (SRT) and single-nucleus RNA-sequencing (snRNA-seq) data from anterior human hippocampus in ten adult neurotypical donors.

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Background: Relative cell type fraction estimates in bulk RNA-sequencing data are important to control for cell composition differences across heterogenous tissue samples. While there exist algorithms to estimate the cell type proportions in tissues, a major challenge is the algorithms can show reduced performance if using tissues that have varying cell sizes, such as in brain tissue. In this way, without adjusting for differences in cell sizes, computational algorithms estimate the relative fraction of RNA attributable to each cell type, rather than the relative fraction of cell types, leading to potentially biased estimates in cellular composition.

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Background: Red breast syndrome (RBS) is represented as idiopathic cutaneous erythema overlying the acellular dermal matrix (ADM) after implant-based breast reconstruction without other signs and symptoms of infection. Although a number of etiologies including lymphatic disruption, delayed hypersensitivity reaction to ADM, and residual DNA within ADM have been suggested for RBS, consensus regarding risk factors and treatment for RBS has been reached yet. Thus, the aim of this study was to find risk factors for RBS and introduce our experience of successful treatment of RBS.

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Cellular deconvolution of bulk RNA-sequencing data using single cell/nuclei RNA-seq reference data is an important strategy for estimating cell type composition in heterogeneous tissues, such as the human brain. Here, we generate a multi-assay dataset in postmortem human dorsolateral prefrontal cortex from 22 tissue blocks, including bulk RNA-seq, reference snRNA-seq, and orthogonal measurement of cell type proportions with RNAScope/ImmunoFluorescence. We use this dataset to evaluate six deconvolution algorithms.

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Advances in spatially-resolved transcriptomics (SRT) technologies have propelled the development of new computational analysis methods to unlock biological insights. The lowering cost of SRT data generation presents an unprecedented opportunity to create large-scale spatial atlases and enable population-level investigation, integrating SRT data across multiple tissues, individuals, species, or phenotypes. Here, unique challenges are described in the SRT data integration, where the analytic impact of varying spatial and biological resolutions is characterized and explored.

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Article Synopsis
  • The study investigates how neurodegenerative disorders, particularly Alzheimer's disease, affect brain microenvironments by analyzing brain tissue lesions associated with amyloid-β and hyperphosphorylated tau.
  • Researchers used the advanced 10x Genomics Visium Spatial Proteogenomics platform to explore gene expression changes in post-mortem human brains, specifically in the inferior temporal cortex during late-stage Alzheimer's.
  • The findings offer insights into molecular processes linked to brain pathology, provide a framework for analyzing spatial gene expression, and deliver accessible interactive resources for the scientific community to explore related datasets.
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Argonaute (AGO), a component of RNA-induced silencing complexes (RISCs), is a representative RNA-binding protein (RBP) known to bind with mature microRNAs (miRNAs) and is directly involved in post-transcriptional gene silencing. However, despite the biological significance of miRNAs, the roles of other miRNA-binding proteins (miRBPs) remain unclear in the regulation of miRNA loading, dissociation from RISCs and extracellular release. In this study, we performed protein arrays to profile miRBPs and identify 118 RBPs that directly bind to miRNAs.

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Advances in spatially-resolved transcriptomics (SRT) technologies have propelled the development of new computational analysis methods to unlock biological insights. As the cost of generating these data decreases, these technologies provide an exciting opportunity to create large-scale atlases that integrate SRT data across multiple tissues, individuals, species, or phenotypes to perform population-level analyses. Here, we describe unique challenges of varying spatial resolutions in SRT data, as well as highlight the opportunities for standardized preprocessing methods along with computational algorithms amenable to atlas-scale datasets leading to improved sensitivity and reproducibility in the future.

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Background: Magnetic hyperthermia (MHT) has emerged as a promising therapeutic approach in the field of radiation oncology due to its superior precision in controlling temperature and managing the heating area compared to conventional hyperthermia. Recent studies have proposed solutions to address clinical safety concerns associated with MHT, which arise from the use of highly concentrated magnetic nanoparticles and the strong magnetic field needed to induce hyperthermic effects. Despite these efforts, challenges remain in quantifying therapeutic outcomes and developing treatment plan systems for combining MHT with radiation therapy (RT).

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Article Synopsis
  • The study focuses on the molecular organization of the human neocortex, particularly the dorsolateral prefrontal cortex, using advanced spatial transcriptomic technologies.
  • Researchers created a detailed neuroanatomical atlas that highlights different spatial domains based on gene expression patterns, moving beyond traditional histological layers.
  • By integrating data from various sources, the team identified specific cell types and interactions linked to neuropsychiatric disorders, showing how these relate to spatial domains in the brain.
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Article Synopsis
  • - The study investigates the unique cell types within the human hippocampus, focusing on their roles in learning, memory, and cognition, using advanced methods like spatially-resolved transcriptomics (SRT) and single-nucleus RNA-sequencing (snRNA-seq) on tissue from ten neurotypical adults.
  • - Researchers employed non-negative matrix factorization (NMF) to analyze gene expression patterns across different neuronal cell types, discovering variations in excitatory and inhibitory responses within distinct spatial regions of the hippocampus.
  • - The findings include the identification of molecular profiles for various hippocampal cell types and suggest these profiles’ relevance to learning capabilities, while making the resulting data publicly available for further research.
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Relative cell type fraction estimates in bulk RNA-sequencing data are important to control for cell composition differences across heterogenous tissue samples. Current computational tools estimate relative RNA abundances rather than cell type proportions in tissues with varying cell sizes, leading to biased estimates. We present , a computational tool to accurately deconvolute cell types with varying sizes.

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Article Synopsis
  • - The study focuses on improving the cellular deconvolution of bulk RNA-seq data using single-cell RNA-seq data to estimate cell type composition in diverse tissues, particularly in the human brain.
  • - Researchers created a detailed multi-assay dataset from 22 postmortem human brain samples, employing various RNA-seq methods and comparing estimated cell proportions with actual measurements from other techniques.
  • - The analysis identified specific deconvolution algorithms that performed best, revealing that factors like cell size and differences in gene quantification can impact the accuracy of these methods in reflecting true tissue composition.
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Norepinephrine (NE) neurons in the locus coeruleus (LC) make long-range projections throughout the central nervous system, playing critical roles in arousal and mood, as well as various components of cognition including attention, learning, and memory. The LC-NE system is also implicated in multiple neurological and neuropsychiatric disorders. Importantly, LC-NE neurons are highly sensitive to degeneration in both Alzheimer's and Parkinson's disease.

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Deconvolution of cell mixtures in "bulk" transcriptomic samples from homogenate human tissue is important for understanding disease pathologies. However, several experimental and computational challenges impede transcriptomics-based deconvolution approaches using single-cell/nucleus RNA-seq reference atlases. Cells from the brain and blood have substantially different sizes, total mRNA, and transcriptional activities, and existing approaches may quantify total mRNA instead of cell type proportions.

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  • Chronic kidney disease can arise from cisplatin chemotherapy, complicating cancer patients' recovery, necessitating research into its molecular mechanisms.
  • MicroRNAs play a crucial role in gene regulation; this study identifies direct interactions between specific microRNAs and messenger RNAs in cisplatin-injured mouse kidneys.
  • The study highlights miR-429-3p's role in promoting cell death through a process called ferroptosis by targeting metabolic pathways for branched-chain amino acids, indicating potential therapeutic strategies.
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Macroautophagy/autophagy contributes to maladaptive kidney repair by inducing pro-fibrotic factors such as FGF2 (fibroblast growth factor 2), but the underlying mechanism remains elusive. Here, we show that EGR1 (early growth response 1) was induced in injured proximal tubules after ischemic acute kidney injury (AKI) and this induction was suppressed by autophagy deficiency in inducible, renal tubule-specific (autophagy related 7) knockout (iRT- KO) mice. In cultured proximal tubular cells, TGFB1 (transforming growth factor beta 1) induced EGR1 and this induction was also autophagy dependent.

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We define and identify a new class of control genes for next-generation sequencing called total RNA expression genes (TREGs), which correlate with total RNA abundance in cell types of different sizes and transcriptional activity. We provide a data-driven method to identify TREGs from single-cell RNA sequencing data, allowing the estimation of total amount of RNA when restricted to quantifying a limited number of genes. We demonstrate our method in postmortem human brain using multiplex single-molecule fluorescent in situ hybridization and compare candidate TREGs against classic housekeeping genes.

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Background: Recurrent laryngeal nerve (RLN) injury and the resulting paralysis is the most common and known complication of thyroid surgery. Several surgical techniques, such as medialization thyroplasty with or without arytenoid adduction and injection laryngoplasty, have been developed to treat RLN injury, but these procedures have specific limitations and complications. In this study, we present the outcomes for our patients who underwent immediate RLN reconstruction during thyroid surgery by analyzing both subjective and objective outcomes.

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Deconvolution of cell mixtures in "bulk" transcriptomic samples from homogenate human tissue is important for understanding the pathologies of diseases. However, several experimental and computational challenges remain in developing and implementing transcriptomics-based deconvolution approaches, especially those using a single cell/nuclei RNA-seq reference atlas, which are becoming rapidly available across many tissues. Notably, deconvolution algorithms are frequently developed using samples from tissues with similar cell sizes.

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Article Synopsis
  • An immediate lymphatic reconstruction (ILR) combining axillary reverse lymphatic mapping and lymphovenous anastomosis is being studied as a new surgical technique aimed at preventing upper extremity lymphedema in breast cancer patients after mastectomy.
  • A cohort study analyzed 213 patients, comparing 30 who underwent ILR with 183 who did not, to assess the effectiveness of this preventive treatment.
  • Results showed a significantly lower incidence of lymphedema in the ILR group (3.8%) compared to the control group (7.7%), indicating that ILR may help reduce the risk, but more extensive research is needed for validation.
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Generation of a molecular neuroanatomical map of the human prefrontal cortex reveals novel spatial domains and cell-cell interactions relevant for psychiatric disease. The molecular organization of the human neocortex has been historically studied in the context of its histological layers. However, emerging spatial transcriptomic technologies have enabled unbiased identification of transcriptionally-defined spatial domains that move beyond classic cytoarchitecture.

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Background: Multispectral fluorescence imaging coupled with linear unmixing is a form of image data collection and analysis that allows for measuring multiple molecular signals in a single biological sample. Multiple fluorescent dyes, each measuring a unique molecule, are simultaneously measured and subsequently "unmixed" to provide a read-out for each molecular signal. This strategy allows for measuring highly multiplexed signals in a single data capture session, such as multiple proteins or RNAs in tissue slices or cultured cells, but can often result in mixed signals and bleed-through problems across dyes.

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The extracellular vesicle exosome mediates intercellular communication by transporting macromolecules such as proteins and ribonucleic acids (RNAs). Determining cargo contents with high accuracy will help decipher the biological processes that exosomes mediate in various contexts. Existing methods for probing exosome cargo molecules rely on a prior exosome isolation procedure.

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