Publications by authors named "Sung Hak Choi"

We designed a novel lyophilization method using controlled rate slow freezing (CSF) with lyoprotective agent (LPA) to achieve intact lipid nanovesicles after lyophilization. During the freezing step, LPA prevented water supercooling, and the freezing rate was controlled by CSF. Regulating the freezing rate by various liquid media was a crucial determinant of membrane disruption, and isopropanol (freezing rate of 0.

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Several antimuscarinics have been commonly used for overactive bladder patients, but dry mouth as a major anticholinergic side effect remains a shortcoming to limit long-term use. The aim of this study was to elucidate the pharmacological properties of DA-8010, a novel muscarinic receptor antagonist selective for urinary bladder over salivary gland. DA-8010 exhibited a high binding affinity for human muscarinic M receptor with pK of 8.

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Purpose: Tedizolid phosphate is a next-generation oxazolidinone prodrug that is transformed into the active moiety tedizolid. Its indication is acute bacterial skin and skin structure infections caused by gram-positive species, including methicillin-resistant Staphylococcus aureus. Although tedizolid phosphate has been marketed in Korea, no data on the pharmacokinetic (PK) properties or tolerability of tedizolid phosphate in Korean subjects are available.

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A series of novel substituted pyridyl phenyl oxazolidinone analogues were synthesized and their structure-activity relationship (SAR) was investigated based on in vitro and in vivo antibacterial activities. The minimum inhibitory concentrations (MICs) of the synthesized compounds against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) ranged from 0.12 to 2.

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Resistance of Gram-positive pathogens to first-line antimicrobial agents has been increasing in many parts of the world. We compared the in vitro activities of torezolid with those of other antimicrobial agents, including linezolid, against clinical isolates of major aerobic and anaerobic bacteria. Torezolid had an MIC(90) of ≤0.

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Background: Mycetoma is a chronic infectious disease of tropical and subtropical countries. It is produced by true fungi and actinobacteria. In México, Nocardia brasiliensis is the main causative agent of mycetoma, producing about 86% of the cases; the gold standard for the therapy of mycetoma by N.

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Two recently synthesized oxazolidinones: (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one (DA-7157) and its corresponding pro-drug (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-2-oxo-5-oxazolidinyl) methyl disodium phosphate (DA-7218), have shown very good activity against several Gram positive bacteria, including Nocardia and Mycobacterium. In the present work we evaluated the therapeutic in vivo effects of DA-7218 on Nocardia brasiliensis. We first determined the plasma concentration of the prodrug in BALB/c mice using several doses and then tested its activity in an in vivo experimental actinomycetoma murine model.

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DA-7867 and DA-7157 are oxazolidinones active against pathogenic aerobic actinomycetes including Nocardia spp. and Mycobacterium tuberculosis. However, the activity of these drugs against nontuberculous mycobacterium (NTM) species is not known.

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The in vitro activities of DA-7157, a novel oxazolidinone, against clinical isolates of Nocardia brasiliensis and Mycobacterium tuberculosis were determined. Equal MIC(50)s and MIC(90)s (0.25 and 0.

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The in vitro activities of DA-7867, a novel oxazolidinone, and garenoxacin (BMS-284756) were compared to those of linezolid in 67 susceptible and drug-resistant clinical isolates of Mycobacterium tuberculosis. DA-7867 was the most active drug with an MIC(90) of 0.125 microg/ml, compared to the MIC(90)s of 4 microg/ml of garenoxacin and 2 microg/ml of linezolid.

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In vitro and in vivo activities of DA-7867 were assessed against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae. All isolates were inhibited by DA-7867 at View Article and Find Full Text PDF

In vitro activities of DA-7867, a novel oxazolidinone, were compared to those of linezolid and commonly used antimicrobials. DA-7867 had the lowest MIC for 90% of the aerobic gram-positive bacterial strains tested, View Article and Find Full Text PDF