| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Chang, Chiao-Nien, et al.
(författare)
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The Design, Structure–Activity, and Kinetic Studies of 3-Benzyl-5-oxa-1,2,3,4-Tetrahydro-2H-chromeno-(3,4-c)pyridin-8-yl Sulfamates as Steroid Sulfatase Inhibitors
- 2022
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Ingår i: Bioorganic chemistry. - : Elsevier BV. - 0045-2068.
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Tidskriftsartikel (refereegranskat)abstract
- Steroid sulfatase inhibitors block the local production of estrogenic steroids and are attractive agents for the treatment of estrogen-dependent cancers. Inspiration of coumarin-based inhibitors, we synthesized thirty-two 5-oxa-1,2,3,4-tetrahydro-2H-chromeno-(3,4-c)pyridin-8-yl sulfamates, focusing on the substitution derivatives on the adjacent phenyl ring and evaluated their abilities to block STS from human placenta and MCF-7 cells. SAR analysis revealed that the incorporation of chlorine at either meta and/or para position of the adjacent phenyl ring of the tricyclic skeleton enhanced STS inhibition. Di-substitutions at the adjacent phenyl ring were superior to mono and tri-substitutions. Further kinetic analysis of these compounds revealed that chloride-bearing compounds, such as 19m, 19v, and 19w, had KI of 0.02 to 0.11 nM and kinact/KI ratios of 8.8-17.5 nM-1min-1, a parameter indicated for the efficiency of irreversible inhibition. We also used the docking model to illustrate the difference in STS inhibitory potency of compounds. Finally, the safety and anti-cancer activity of selected compounds 19m, 19v, and 19w were also studied, showing the results of low cytotoxicity on NHDF cell line and being more potent than irosustat on ZR-75-1 cell, which was a hormone-dependent cancer cell line with high STS expression.
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| 3. |
- Chiu, Pei-Fang, et al.
(författare)
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Design, structure–activity relationships, and enzyme kinetic studies of tricyclic and tetracyclic coumarin–based sulfamates as steroid sulfatase inhibitors
- 2023
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Ingår i: Bioorganic chemistry. - : Elsevier BV. - 0045-2068. ; 138, s. 106581-106581
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Tidskriftsartikel (refereegranskat)abstract
- Inhibition of steroid sulfatase (STS) decreases estrogen production and thus, suppresses tumor proliferation. Inspired by irosustat, the first STS inhibitor in clinical trials, we explored twenty-one tricyclic and tetra-heterocyclic coumarin–based derivatives. Their STS enzyme kinetic parameters, docking models, and cytotoxicity toward breast cancer and normal cells were evaluated. Tricyclic derivative 9e and tetracyclic derivative 10c were the most promising irreversible inhibitors developed in this study, with KI of 0.05 and 0.4 nM, and kinact/KI ratios of 28.6 and 19.1 nM−1min−1 on human placenta STS, respectively.
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| 4. |
- Lee, I-Ming, et al.
(författare)
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A hexasaccharide from capsular polysaccharide of carbapenem-resistant Klebsiella pneumoniae KN2 is a ligand of Toll-like receptor 4
- 2022
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Ingår i: Carbohydrate Polymers. - : ELSEVIER SCI LTD. - 0144-8617 .- 1879-1344. ; 278
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Tidskriftsartikel (refereegranskat)abstract
- Klebsiella pneumoniae serotype KN2 is a carbapenem-resistant strain and leads to the health care-associated in-fections, such as bloodstream infections. Its capsular polysaccharide (CPS) was isolated and cleaved by a specific enzyme from a bacteriophage into a hexasaccharide-repeating unit. With GC-MS, NMR, and Mass analyses, the structure of KN2 CPS was determined to be {-> 3)-beta-D-Glcp-(1 -> 3)-[alpha-D-GlcpA-(1 -> 4)-beta-D-Glcp-(1 -> 6)]-alpha-D-Galp- (1 -> 6)-beta-D-Galp-(1 -> 3)-beta-D-Galp-(1 ->}(n). We demonstrated that 1 mu g/mL CPS could stimulate J774A.1 murine macrophages to release tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in vitro. Also, we proved that KN2 CPS induced the immune response through Toll-like receptor 4 (TLR4) in the human embryonic kidney (HEK)-293 cells. Strikingly, the hexasaccharide alone shows the same immune response as the CPS, suggesting that the hexasaccharide can shape the adaptive immunity to be a potential vaccine adjuvant. The glucuronic acid (GlcA) on other polysaccharides can affect the immune response, but the GlcA-reduced KN2 CPS and hex-asaccharide still maintain their immunomodulatory activities.
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