Publications by authors named "Sangmi Oh"

Mycobacterial species in nature are found in abundance in sphagnum peat bogs where they compete for nutrients with a variety of microorganisms including fungi. We screened a collection of fungi isolated from sphagnum bogs by co-culture with Mycobacterium tuberculosis (Mtb) to look for inducible expression of antitubercular agents and identified 5 fungi that produced cidal antitubercular agents upon exposure to live Mtb. Whole genome sequencing of these fungi followed by fungal RNAseq after Mtb exposure allowed us to identify biosynthetic gene clusters induced by co-culture.

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Mycobacterial species in nature are found in abundance in sphagnum peat bogs where they compete for nutrients with a variety of microorganisms including fungi. We screened a collection of fungi isolated from sphagnum bogs by co-culture with () to look for inducible expression of antitubercular agents and identified five fungi that produced cidal antitubercular agents upon exposure to live . Whole genome sequencing of these fungi followed by fungal RNAseq after exposure allowed us to identify biosynthetic gene clusters induced by co-culture.

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Despite the availability of effective treatments, hypertension control rates remain inadequate in the United States and locally in Los Angeles County. To address this health condition, QueensCare Health Centers developed and launched a team-based hypertension management program that was led by clinical pharmacists and designed to mitigate treatment barriers encountered at the system, provider, and patient levels. System- and provider-focused strategies included incorporating self-monitored blood pressure values into the electronic health record and retraining clinicians to regularly review these values; adding a community health worker to the disease management team; and utilizing clinical pharmacists to assess and titrate medications.

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Linezolid is a drug with proven human antitubercular activity whose use is limited to highly drug-resistant patients because of its toxicity. This toxicity is related to its mechanism of action─linezolid inhibits protein synthesis in both bacteria and eukaryotic mitochondria. A highly selective and potent series of oxazolidinones, bearing a 5-aminomethyl moiety (in place of the typical 5-acetamidomethyl moiety of linezolid), was identified.

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Tuberculosis (TB) is notorious as the leading cause of death worldwide due to a single infectious entity and its causative agent, (), has been able to evolve resistance to all existing drugs in the treatment arsenal complicating disease management programs. In drug discovery efforts, natural products are important starting points in generating novel scaffolds that have evolved to specifically bind to vulnerable targets not only in pathogens such as , but also in mammalian targets associated with human diseases. Structural diversity is one of the most attractive features of natural products.

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Article Synopsis
  • The study addresses the urgent issue of drug-resistant tuberculosis, emphasizing the necessity for new drug candidates to improve treatment options.
  • Researchers discovered a potent compound, (4-benzylpiperidin-1-yl)(1-(5-phenyl-1,3,4-oxadiazol-2-yl)piperidin-4-yl)methanone, through high-throughput screening, which showed effectiveness against both drug-resistant and drug-susceptible strains of TB.
  • Analysis of resistant mutant strains identified mutations in the DprE1 gene, suggesting a new avenue for drug development and highlighting the potential of the novel oxadiazole structure as a valuable tool in TB treatment.
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Mycobacterium tuberculosis (Mtb), perhaps more than any other organism, is intrinsically appealing to chemical biologists. Not only does the cell envelope feature one of the most complex heteropolymers found in nature but many of the interactions between Mtb and its primary host (we humans) rely on lipid and not protein mediators. Many of the complex lipids, glycolipids, and carbohydrates biosynthesized by the bacterium still have unknown functions, and the complexity of the pathological processes by which tuberculosis (TB) disease progress offers many opportunities for these molecules to influence the human response.

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Neuroinflammation is one of the critical processes implicated in central nervous system (CNS) diseases. Therefore, alleviating neuroinflammation has been highlighted as a therapeutic strategy for treating CNS disorders. However, the complexity of neuroinflammatory processes and poor drug transport to the brain are considerable hurdles to the efficient control of neuroinflammation using small-molecule therapeutics.

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Article Synopsis
  • Mucosal-associated invariant T (MAIT) cells are a type of immune cell that can recognize specific non-peptide antigens, and they show potential in attacking tumors when activated.
  • In this study, researchers found that MAIT cells activated by a synthetic antigen (5-OP-RU) and a TLR9 agonist (CpG) greatly expanded and enhanced their activity, leading to improved antitumor responses in mice with various types of cancer.
  • The effectiveness of this MAIT-directed immunotherapy was demonstrated even when the tumor cells lacked MR1, indicating that MAIT cells might use an indirect method to combat cancer, making them promising candidates for future cancer treatments.
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Targeting MAIT cells holds promise for the treatment of different diseases and infections. We previously showed that treatment of Mycobacterium tuberculosis infected mice with 5-OP-RU, a major antigen for MAIT cells, expands MAIT cells and enhances bacterial control. Here we treated M.

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This study evaluated the potential use of senescence-inducing small molecules in the treatment of melanoma. We screened commercially available small-molecule libraries with high-throughput screening and high-content screening image-based technology. Our findings showed an initial hit with the embedded -arylpiperidine-3-carboxamide scaffold-induced senescence-like phenotypic changes in human melanoma A375 cells without serious cytotoxicity against normal cells.

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More than two decades have elapsed since the publication of the first genome sequence of () which, shortly thereafter, enabled methods to determine gene essentiality in the pathogen. Despite this, target-based approaches have not yielded drugs that have progressed to clinical testing. Whole-cell screening followed by elucidation of mechanism of action has to date been the most fruitful approach to progressing inhibitors into the tuberculosis drug discovery pipeline although target-based approaches are gaining momentum.

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Tryptophan biosynthesis represents an important potential drug target for new anti-TB drugs. We identified a series of indole-4-carboxamides with potent antitubercular activity. In vitro, Mycobacterium tuberculosis (Mtb) acquired resistance to these compounds through three discrete mechanisms: (1) a decrease in drug metabolism via loss-of-function mutations in the amidase that hydrolyses these carboxamides, (2) an increased biosynthetic rate of tryptophan precursors via loss of allosteric feedback inhibition of anthranilate synthase (TrpE), and (3) mutation of tryptophan synthase (TrpAB) that decreased incorporation of 4-aminoindole into 4-aminotryptophan.

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Pyrazolo[1,5-]pyrimidin-7(4)-one was identified through high-throughput whole-cell screening as a potential antituberculosis lead. The core of this scaffold has been identified several times previously and has been associated with various modes of action against (). We explored this scaffold through the synthesis of a focused library of analogues and identified key features of the pharmacophore while achieving substantial improvements in antitubercular activity.

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Current research suggests therapy-induced senescence (TIS) of cancer cells characterized by distinct morphological and biochemical phenotypic changes represent a novel functional target that may enhance the effectiveness of cancer therapy. In order to identify novel small-molecule inducers of cellular senescence and determine the potential to be used for the treatment of melanoma, a new method of high-throughput screening (HTS) and high-contents screening (HCS) based on the detection of morphological changes was designed. This image-based and whole cell-based technology was applied to screen and select a novel class of antiproliferative agents on cancer cells, 4H-chromeno[2,3-d]pyrimidin-4-one derivatives, which induced senescence-like phenotypic changes in human melanoma A375 cells without serious cytotoxicity against normal cells.

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Mucosal-associated invariant T (MAIT) cells are potential targets of vaccination and host-directed therapeutics for tuberculosis, but the role of MAIT cells during Mycobacterium tuberculosis (Mtb) infection in vivo is not well understood. Here we find that following Mtb infection MAIT cells mount minimal responses, and MAIT cell-deficient MR1 mice display normal survival. Preinfection expansion of MAIT cells through 5-OP-RU vaccination fails to protect against subsequent Mtb challenge.

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Mechanisms of magnesium homeostasis in are poorly understood. Here, we describe the characterization of a pyrimidinetrione amide scaffold that disrupts magnesium homeostasis in the pathogen by direct binding to the CorA Mg/Co transporter. Mutations in domains of CorA that are predicted to regulate the pore opening in response to Mg ions conferred resistance to this scaffold.

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Magnesium plays an important role in infection with Mycobacterium tuberculosis ( Mtb) as a signal of the extracellular environment, as a cofactor for many enzymes, and as a structural element in important macromolecules. Raltegravir, an antiretroviral drug that inhibits HIV-1 integrase is known to derive its potency from selective sequestration of active-site magnesium ions in addition to binding to a hydrophobic pocket. In order to determine if essential Mtb-related phosphoryl transfers could be disrupted in a similar manner, a directed screen of known molecules with integrase inhibitor-like pharmacophores ( N-alkyl-5-hydroxypyrimidinone carboxamides) was performed.

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The use of chemical techniques to study biological systems (often referred to currently as chemical biology) has become a powerful tool for both drug discovery and the development of novel diagnostic strategies. In tuberculosis, such tools have been applied to identifying drug targets from hit compounds, matching high-throughput screening hits against large numbers of isolated protein targets and identifying classes of enzymes with important functions. Metabolites unique to mycobacteria have provided important starting points for the development of innovative tools.

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Cell division cycle 25 (Cdc25) is an evolutionarily conserved phosphatase that promotes cell cycle progression by activating cyclin-dependent kinases (Cdks) which are inactivated by Wee1/Myt1 kinases. It was previously reported that cdc-25.2 promotes oocyte maturation and intestinal cell divisions in Caenorhabditis elegans hermaphrodites.

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Cell division cycle 25 (cdc25) is an evolutionarily conserved phosphatase that promotes cell cycle progression. Among the four cdc25 orthologs in Caenorhabditis elegans, we found that cdc-25.4 mutant males failed to produce outcrossed progeny.

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Objectives: The role of celecoxib in preventing and treating tumors has attracted broad attention in recent years because of its selective and specific inhibition of COX-2 activity. We investigated the inhibitory effects and mechanisms of celecoxib combined with 5-fluorouracil (5-FU) on proliferation of squamous cell carcinoma cells in vivo and in vitro.

Study Design: Animal study and basic research.

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Background: Endocannabinoids have recently drawn attention as promising anti-cancer agents. We previously observed that anandamide (AEA), one of the representative endocannabinoids, effectively inhibited the proliferation of head and neck squamous cell carcinoma (HNSCC) cell lines in a receptor-independent manner. In this study, using HNSCC cell lines, we examined the anti-cancer effects and the mechanisms of action of docosahexaenoyl ethanolamide (DHEA) and N-arachidonoyl-L-alanine (NALA), which are polyunsaturated fatty acid (PUFA)-based ethanolamides like AEA.

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Herein we report molecular shape-dependent nonspecific labeling of photoaffinity linkers (PLs) in the cellular proteome. Linear PLs have a greater tendency to engage in nonspecific binding than branched PLs. Exploiting this property, we discovered a smaller branched diazirine-based PL as the best photoaffinity probe with minimal nonspecific binding characteristics from among 5 probes with different PLs.

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