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  1. Article ; Online: The Role of the Stem-Loop A RNA Promoter in Flavivirus Replication.

    Choi, Kyung H

    Viruses

    2021  Volume 13, Issue 6

    Abstract: An essential challenge in the lifecycle of RNA viruses is identifying and replicating the viral genome amongst all the RNAs present in the host cell cytoplasm. Yet, how the viral polymerase selectively recognizes and copies the viral RNA genome is poorly ...

    Abstract An essential challenge in the lifecycle of RNA viruses is identifying and replicating the viral genome amongst all the RNAs present in the host cell cytoplasm. Yet, how the viral polymerase selectively recognizes and copies the viral RNA genome is poorly understood. In flaviviruses, the 5'-end of the viral RNA genome contains a 70 nucleotide-long stem-loop, called stem-loop A (SLA), which functions as a promoter for genome replication. During replication, flaviviral polymerase NS5 specifically recognizes SLA to both initiate viral RNA synthesis and to methylate the 5' guanine cap of the nascent RNA. While the sequences of this region vary between different flaviviruses, the three-way junction arrangement of secondary structures is conserved in SLA, suggesting that viruses recognize a common structural feature to replicate the viral genome rather than a particular sequence. To better understand the molecular basis of genome recognition by flaviviruses, we recently determined the crystal structures of flavivirus SLAs from dengue virus (DENV) and Zika virus (ZIKV). In this review, I will provide an overview of (1) flaviviral genome replication; (2) structures of viral SLA promoters and NS5 polymerases; and (3) and describe our current model of how NS5 polymerases specifically recognize the SLA at the 5' terminus of the viral genome to initiate RNA synthesis at the 3' terminus.
    MeSH term(s) Binding Sites ; Flavivirus/genetics ; Flavivirus/physiology ; Genome, Viral ; Inverted Repeat Sequences ; Promoter Regions, Genetic ; Protein Binding ; RNA, Viral/genetics ; Virus Replication/genetics ; Virus Replication/physiology
    Chemical Substances RNA, Viral
    Language English
    Publishing date 2021-06-09
    Publishing country Switzerland
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 2516098-9
    ISSN 1999-4915 ; 1999-4915
    ISSN (online) 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v13061107
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: High-resolution RNA tertiary structures in Zika virus stem-loop A for the development of inhibitory small molecules.

    Tipo, Jerricho / Gottipati, Keerthi / Choi, Kyung H

    RNA (New York, N.Y.)

    2024  

    Abstract: Flaviviruses such as Zika (ZIKV) and dengue virus (DENV) are positive-sense RNA viruses belonging to Flaviviridae. The flavivirus genome contains a 5' end stem-loop promoter sequence known as stem-loop A (SLA) that is recognized by the flavivirus ... ...

    Abstract Flaviviruses such as Zika (ZIKV) and dengue virus (DENV) are positive-sense RNA viruses belonging to Flaviviridae. The flavivirus genome contains a 5' end stem-loop promoter sequence known as stem-loop A (SLA) that is recognized by the flavivirus polymerase NS5 during viral RNA synthesis and 5' guanosine cap methylation. The crystal structures of ZIKV and DENV SLAs show a well-defined fold, consisting of a bottom stem, side loop, and top stem-loop, providing unique interaction sites for small-molecule inhibitors to disrupt the promoter function. To facilitate identification of small molecule binding sites in flavivirus SLA, we determined high-resolution structures of bottom and top stems of ZIKV SLA, which contain a single U- or G-bulge, respectively. Both bulge nucleotides exhibit multiple orientations, from folded back on the adjacent nucleotide to flipped out of the helix, and are stabilized by stacking or base triple interactions. These structures suggest that even a single unpaired nucleotide can provide flexibility to RNA structures and its conformation is mainly determined by the stabilizing chemical environment. To facilitate discovery of small molecule inhibitors that interfere with the functions of ZIKV SLA, we screened and identified compounds that bind to the bottom and top stems of ZIKV SLA.
    Language English
    Publishing date 2024-02-21
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1241540-6
    ISSN 1469-9001 ; 1355-8382
    ISSN (online) 1469-9001
    ISSN 1355-8382
    DOI 10.1261/rna.079796.123
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: A remineralizing orthodontic etchant that utilizes calcium phosphate ion clusters.

    Kim, Hyeryeong / Yoo, Kyung-Hyeon / Yoon, Seog-Young / Choi, Youn-Kyung / Kim, Yong-Il

    Frontiers in bioengineering and biotechnology

    2022  Volume 10, Page(s) 944869

    Abstract: This study aimed to investigate whether a phosphoric acid (H ...

    Abstract This study aimed to investigate whether a phosphoric acid (H
    Language English
    Publishing date 2022-08-31
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2719493-0
    ISSN 2296-4185
    ISSN 2296-4185
    DOI 10.3389/fbioe.2022.944869
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: The Role of the Stem-Loop A RNA Promoter in Flavivirus Replication

    Choi, Kyung H.

    Viruses. 2021 June 09, v. 13, no. 6

    2021  

    Abstract: An essential challenge in the lifecycle of RNA viruses is identifying and replicating the viral genome amongst all the RNAs present in the host cell cytoplasm. Yet, how the viral polymerase selectively recognizes and copies the viral RNA genome is poorly ...

    Abstract An essential challenge in the lifecycle of RNA viruses is identifying and replicating the viral genome amongst all the RNAs present in the host cell cytoplasm. Yet, how the viral polymerase selectively recognizes and copies the viral RNA genome is poorly understood. In flaviviruses, the 5′-end of the viral RNA genome contains a 70 nucleotide-long stem-loop, called stem-loop A (SLA), which functions as a promoter for genome replication. During replication, flaviviral polymerase NS5 specifically recognizes SLA to both initiate viral RNA synthesis and to methylate the 5′ guanine cap of the nascent RNA. While the sequences of this region vary between different flaviviruses, the three-way junction arrangement of secondary structures is conserved in SLA, suggesting that viruses recognize a common structural feature to replicate the viral genome rather than a particular sequence. To better understand the molecular basis of genome recognition by flaviviruses, we recently determined the crystal structures of flavivirus SLAs from dengue virus (DENV) and Zika virus (ZIKV). In this review, I will provide an overview of (1) flaviviral genome replication; (2) structures of viral SLA promoters and NS5 polymerases; and (3) and describe our current model of how NS5 polymerases specifically recognize the SLA at the 5′ terminus of the viral genome to initiate RNA synthesis at the 3′ terminus.
    Keywords Dengue virus ; RNA ; Zika virus ; cytoplasm ; guanine ; models ; viral genome
    Language English
    Dates of publication 2021-0609
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2516098-9
    ISSN 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v13061107
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Trajectory of lung function in diabetic adults: A 16-year follow-up study of community-based prospective cohorts.

    Choi, Wonsuk / Moon, Joon Ho / Choi, Hayoung / Lee, Hyun / Kim, Hee Kyung / Kang, Ho-Cheol / Cho, Nam H

    Respirology (Carlton, Vic.)

    2024  Volume 29, Issue 5, Page(s) 413–420

    Abstract: Background and objective: To investigate the difference in lung function according to diabetes status in a community-based prospective study.: Methods: Individuals aged 40-69 years from two community-based cohorts were followed prospectively for 16 ... ...

    Abstract Background and objective: To investigate the difference in lung function according to diabetes status in a community-based prospective study.
    Methods: Individuals aged 40-69 years from two community-based cohorts were followed prospectively for 16 years. A spirometer was used to evaluate lung function at baseline, and lung function tests were carried out biennially thereafter. Multivariable linear regression analysis was performed for the cross-sectional and longitudinal analyses based on diabetes status.
    Results: Among the 6483 subjects, 2114 (32.6%) had prediabetes and 671 (10.4%) had diabetes. The prediabetes and diabetes groups had lower baseline % predicted values of forced expiratory volume in 1 s (FEV
    Conclusion: Diabetes is associated with a lower baseline lung function and a faster rate of deterioration.
    MeSH term(s) Adult ; Humans ; Follow-Up Studies ; Prospective Studies ; Prediabetic State/epidemiology ; Cross-Sectional Studies ; Diabetes Mellitus/epidemiology ; Forced Expiratory Volume ; Vital Capacity ; Lung
    Language English
    Publishing date 2024-01-07
    Publishing country Australia
    Document type Journal Article
    ZDB-ID 1435849-9
    ISSN 1440-1843 ; 1323-7799
    ISSN (online) 1440-1843
    ISSN 1323-7799
    DOI 10.1111/resp.14658
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Effect of physical activity on incident atrial fibrillation in individuals with varying duration of diabetes: a nationwide population study.

    Choi, JungMin / Lee, So-Ryoung / Choi, Eue-Keun / Lee, Kyung-Yeon / Ahn, Hyo-Jeong / Kwon, Soonil / Han, Kyung-Do / Oh, Seil / Lip, Gregory Y H

    Cardiovascular diabetology

    2024  Volume 23, Issue 1, Page(s) 115

    Abstract: Background: Diabetes mellitus (DM) duration affects incident atrial fibrillation (AF) risk; the effect of physical activity on mitigating AF risk related to varying DM duration remains unknown. We assessed the effect of physical activity on incident AF ... ...

    Abstract Background: Diabetes mellitus (DM) duration affects incident atrial fibrillation (AF) risk; the effect of physical activity on mitigating AF risk related to varying DM duration remains unknown. We assessed the effect of physical activity on incident AF in patients with DM with respect to known DM duration.
    Methods: Patients with type 2 DM who underwent the Korean National Health Insurance Service health examination in 2015-2016 were grouped by DM duration: new onset and < 5, 5-9, and ≥ 10 years. Physical activity was classified into four levels: 0, < 500, 500-999, 1,000-1,499, and ≥ 1,500 metabolic equivalent task (MET)-min/week, with the primary outcome being new-onset AF.
    Results: The study enrolled 2,392,486 patients (aged 59.3 ± 12.0 years, 39.8% female) with an average follow-up of 3.9 ± 0.8 years and mean DM duration of 5.3 ± 5.1 years. Greater physical activity was associated with a lower AF risk. Lowering of incident AF risk varied with different amounts of physical activity in relation to known DM duration. Among patients with new-onset DM, DM duration < 5 years and 5-9 years and 1,000-1,499 MET-min/week exhibited the lowest AF risk. Physical activity ≥ 1,500 MET-min/week was associated with the lowest incident AF risk in patients with DM duration ≥ 10 years (by 15%), followed DM duration of 5-9 years (12%) and < 5 years (9%) (p-for-interaction = 0.002).
    Conclusions: Longer DM duration was associated with a high risk of incident AF, while increased physical activity generally reduced AF risk. Engaging in > 1,500 MET-min/week was associated with the greatest AF risk reduction in patients with longer DM duration, highlighting the potential benefits of higher activity levels for AF prevention.
    MeSH term(s) Humans ; Female ; Male ; Atrial Fibrillation/diagnosis ; Atrial Fibrillation/epidemiology ; Atrial Fibrillation/prevention & control ; Risk Factors ; Incidence ; Diabetes Mellitus, Type 2/diagnosis ; Diabetes Mellitus, Type 2/epidemiology ; Diabetes Mellitus, Type 2/complications ; Exercise
    Language English
    Publishing date 2024-03-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 2093769-6
    ISSN 1475-2840 ; 1475-2840
    ISSN (online) 1475-2840
    ISSN 1475-2840
    DOI 10.1186/s12933-024-02194-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Association between antithrombotic therapy after stroke in patients with atrial fibrillation and the risk of net clinical outcome: an observational cohort study.

    Ahn, Hyo-Jeong / Lee, So-Ryoung / Choi, JungMin / Lee, Kyung-Yeon / Kwon, Soonil / Choi, Eue-Keun / Oh, Seil / Lip, Gregory Y H

    Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology

    2024  Volume 26, Issue 2

    Abstract: Aims: Data on the optimal use of antithrombotic drugs and associated clinical outcomes in patients with atrial fibrillation (AF) and acute ischaemic stroke (IS) are limited. We investigated the prescription patterns of antithrombotics in community ... ...

    Abstract Aims: Data on the optimal use of antithrombotic drugs and associated clinical outcomes in patients with atrial fibrillation (AF) and acute ischaemic stroke (IS) are limited. We investigated the prescription patterns of antithrombotics in community practice and long-term clinical prognosis according to early post-stroke antithrombotic therapy in patients with AF and acute IS.
    Methods and results: Patients with AF who were admitted for acute IS at a single tertiary hospital in 2010-2020 were retrospectively reviewed. Clinical profiles including the aetiology of stroke and prescription patterns of antithrombotics were identified. The net clinical outcome (NCO)-the composite of recurrent stroke, any bleeding, hospitalization or emergency department visits for cardiovascular (CV) events, and death-was compared according to the antithrombotic therapy at the first outpatient clinic visit [oral anticoagulation (OAC) alone vs. antiplatelet (APT) alone vs. OAC/APT(s)] following discharge. A total of 918 patients with AF and acute IS (mean age, 72.6 years; male, 59.3%; mean CHA₂DS₂-VASc score 3.3) were analysed. One-third (33.9%, n = 310) of patients were simultaneously diagnosed with AF and IS. The most common aetiology of IS was cardioembolism (71.2%), followed by undetermined aetiology (19.8%) and large artery atherosclerosis (6.0%). OAC, APT(s), and concomitant OAC and APT(s) were prescribed in 33.4%, 11.1%, and 53.4% of patients during admission that changed to 67.0%, 9.1%, and 21.7% at the first outpatient clinic, and were mostly continued up to one year after IS. Non-prescription of OAC was observed in 11.3% of post-stroke patients with AF. During a median follow-up of 2.1 years, the overall incidence rate of NCO per 100 patient-year (PY) was 20.14. APT(s) monotherapy presented the highest cumulative risk of NCO (adjusted hazard ratio 1.47, 95% confidence interval 1.08-2.00, P = 0.015; with reference to OAC monotherapy) mainly driven by the highest rates of recurrent stroke and any bleeding. OAC/APT(s) combination therapy was associated with a 1.62-fold significantly higher risk of recurrent stroke (P = 0.040) and marginally higher risk of any bleeding than OAC monotherapy.
    Conclusion: Approximately one-third of acute IS in AF have a distinctive mechanism from cardioembolism. Although APT was frequently prescribed in post-stroke patients with AF, no additive clinical benefit was observed. Adherence to OAC treatment is essential to prevent further CV adverse events in patients with AF and IS.
    MeSH term(s) Humans ; Male ; Aged ; Stroke/diagnosis ; Stroke/epidemiology ; Stroke/etiology ; Atrial Fibrillation/diagnosis ; Atrial Fibrillation/drug therapy ; Atrial Fibrillation/epidemiology ; Fibrinolytic Agents/adverse effects ; Anticoagulants/adverse effects ; Platelet Aggregation Inhibitors/adverse effects ; Retrospective Studies ; Brain Ischemia ; Risk Factors ; Hemorrhage/chemically induced ; Cohort Studies ; Ischemic Stroke ; Treatment Outcome ; Administration, Oral
    Chemical Substances Fibrinolytic Agents ; Anticoagulants ; Platelet Aggregation Inhibitors
    Language English
    Publishing date 2024-01-29
    Publishing country England
    Document type Observational Study ; Journal Article
    ZDB-ID 1449879-0
    ISSN 1532-2092 ; 1099-5129
    ISSN (online) 1532-2092
    ISSN 1099-5129
    DOI 10.1093/europace/euae033
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Flavivirus proteases: The viral Achilles heel to prevent future pandemics.

    Teramoto, Tadahisa / Choi, Kyung H / Padmanabhan, Radhakrishnan

    Antiviral research

    2022  Volume 210, Page(s) 105516

    Abstract: Flaviviruses are important human pathogens and include dengue (DENV), West Nile (WNV), Yellow fever virus (YFV), Japanese encephalitis (JEV) and Zika virus (ZIKV). DENV, transmitted by mosquitoes, causes diseases ranging in severity from mild dengue ... ...

    Abstract Flaviviruses are important human pathogens and include dengue (DENV), West Nile (WNV), Yellow fever virus (YFV), Japanese encephalitis (JEV) and Zika virus (ZIKV). DENV, transmitted by mosquitoes, causes diseases ranging in severity from mild dengue fever with non-specific flu-like symptoms to fatal dengue hemorrhagic fever and dengue shock syndrome. DENV infections are caused by four serotypes, DENV1-4, which interact differently with antibodies in blood serum. The incidence of DENV infection has increased dramatically in recent decades and the CDC estimates 400 million dengue infections occur each year, resulting in ∼25,000 deaths mostly among children and elderly people. Similarly, ZIKV infections are caused by infected mosquito bites to humans, can be transmitted sexually and through blood transfusions. If a pregnant woman is infected, the virus can cross the placental barrier and can spread to her fetus, causing severe brain malformations in the child including microcephaly and other birth defects. It is noteworthy that the neurological manifestations of ZIKV were also observed in DENV endemic regions, suggesting that pre-existing antibody response to DENV could augment ZIKV infection. WNV, previously unknown in the US (and known to cause only mild disease in Middle East), first arrived in New York city in 1999 (NY99) and spread throughout the US and Canada by Culex mosquitoes and birds. WNV is now endemic in North America. Thus, emerging and re-emerging flaviviruses are significant threat to human health. However, vaccines are available for only a limited number of flaviviruses, and antiviral therapies are not available for any flavivirus. Hence, there is an urgent need to develop therapeutics that interfere with essential enzymatic steps, such as protease in the flavivirus lifecycle as these viruses possess significant threat to future pandemics. In this review, we focus on our E. coli expression of NS2B hydrophilic domain (NS2BH) covalently linked to NS3 protease domain (NS3Pro) in their natural context which is processed by the combined action of both subunits of the NS2B-NS3Pro precursor. Biochemical activities of the viral protease such as solubility and autoproteolysis of NS2BH-NS3Pro linkage depended on the C-terminal portion of NS2BH linked to the NS3Pro domain. Since 2008, we also focus on the use of the recombinant protease in high throughput screens and characterization of small molecular compounds identified in these screens.
    MeSH term(s) Animals ; Female ; Humans ; Pregnancy ; Dengue/prevention & control ; Dengue Virus ; Flavivirus/enzymology ; Pandemics ; Peptide Hydrolases ; Placenta ; Zika Virus ; Zika Virus Infection/prevention & control ; Flavivirus Infections/prevention & control
    Chemical Substances Peptide Hydrolases (EC 3.4.-)
    Language English
    Publishing date 2022-12-29
    Publishing country Netherlands
    Document type Review ; Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 306628-9
    ISSN 1872-9096 ; 0166-3542
    ISSN (online) 1872-9096
    ISSN 0166-3542
    DOI 10.1016/j.antiviral.2022.105516
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Impact of Physical Activity on Clinical Outcomes in AF Patients Undergoing Catheter Ablation.

    Kwon, Soonil / Lee, So-Ryoung / Choi, Eue-Keun / Lee, Seung-Woo / Han, Kyung-Do / Ahn, Hyo-Jeong / Oh, Seil / Lip, Gregory Y H

    JACC. Asia

    2023  Volume 3, Issue 5, Page(s) 819–820

    Language English
    Publishing date 2023-10-17
    Publishing country United States
    Document type Journal Article
    ISSN 2772-3747
    ISSN (online) 2772-3747
    DOI 10.1016/j.jacasi.2023.08.008
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Combination of early rhythm control and healthy lifestyle on the risk of stroke in elderly patients with new-onset atrial fibrillation: a nationwide population-based cohort study.

    Lim, Woo-Hyun / Lee, So-Ryoung / Choi, Eue-Keun / Lee, Seung-Woo / Han, Kyung-Do / Oh, Seil / Lip, Gregory Y H

    Frontiers in cardiovascular medicine

    2024  Volume 11, Page(s) 1346414

    Abstract: Background: The impact of early rhythm control (ERC) combined with healthy lifestyle (HLS) on the risk of ischemic stroke in elderly patients with atrial fibrillation (AF) remains unaddressed.: Objective: To evaluate the impact of combined ERC and ... ...

    Abstract Background: The impact of early rhythm control (ERC) combined with healthy lifestyle (HLS) on the risk of ischemic stroke in elderly patients with atrial fibrillation (AF) remains unaddressed.
    Objective: To evaluate the impact of combined ERC and HLS on the risk of stroke in elderly patients with new-onset AF.
    Methods: Using the Korean National Health Insurance Service database, we included patients aged ≥75 years with new-onset AF from January 2009 to December 2016 (
    Results: Median follow-up duration of the study cohort was 3.4 years. After adjusting for multiple variables, groups 2 and 3 were associated with a lower stroke risk (adjusted hazard ratio [aHR]: 95% confidence interval [CI]: 0.867, 0.794-0.948 and 0.713, 0.637-0.798, respectively) than that of group 1. Compared to Group 1, group 4 showed the lowest stroke risk (aHR: 0.694, 95% CI: 0.586-0.822) among all groups, followed by group 3 (0.713, 0.637-0.798) and group 2 (0.857, 0.794-0.948), respectively. Group 4 was associated with the lowest risk of all-cause death (aHR: 0.680, 95% CI: 0.613-0.754) and the composite outcome (aHR: 0.708, 95% CI: 0.649-0.772).
    Conclusion: ERC and HLS were associated with a lower risk of ischemic stroke in elderly patients with new-onset AF. Concurrently implementing ERC and maintaining HLS was associated with the lowest risk of death and the composite outcome, with a modest synergistic effect on stroke prevention.
    Language English
    Publishing date 2024-02-15
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2781496-8
    ISSN 2297-055X
    ISSN 2297-055X
    DOI 10.3389/fcvm.2024.1346414
    Database MEDical Literature Analysis and Retrieval System OnLINE

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