Publications by authors named "Eunsil Choi"

13 Publications

  • Page 1 of 1

Effects of a Comprehensive Antimicrobial Stewardship Program in a Surgical Intensive Care Unit.

Int J Infect Dis 2021 Feb 24. Epub 2021 Feb 24.

Department of Critical Care Medicine and Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address:

Objectives: We evaluated the effects of a comprehensive ASP at a surgical intensive care unit (SICU).

Methods: The ASP was implemented from March 2018 to February 2019 at an SICU in a teaching hospital. An infectious disease physician and a pharmacist visited the SICU three times a week for prospective audit and feedback. The outcome measures were compared between the ASP period and the same months in the preceding year (pre-ASP period). The primary outcome measure was the use of anti-pseudomonal beta-lactams (APBL). Appropriate antimicrobial de-escalation and ICU mortality rates were also compared.

Results: A total of 182 and 149 patients were included during the pre-ASP and ASP periods, respectively. Although severity was higher in the ASP group (septic shock 39.0% in pre-ASP vs. 65.1% in ASP group, P < 0.001), the use of APBL as definitive treatment was lower during ASP (68.7% vs. 57.7%, OR 0.62, 95% CI 0.40-0.98). Appropriate antimicrobial de-escalation was also improved (63.2% vs. 94.6%, P < 0.001). ICU mortality was comparable (7.7% vs. 7.4%), and significantly lower during the ASP after adjustment (adjusted OR 0.41, 95% CI 0.18-0.92, P = 0.032).

Conclusions: A comprehensive ASP treatment decreased the use of APBL and was associated with an improved outcome.
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http://dx.doi.org/10.1016/j.ijid.2021.02.082DOI Listing
February 2021

Extroversion and Subjective Well-Being Among Korean University Students: The Moderating Role of Attachment.

Psychol Rep 2021 Feb 2:33294121991828. Epub 2021 Feb 2.

Department of Family and Housing Studies, 35032Yeungnam University, Gyeongsan, Republic of Korea.

The purpose of this study was to test the moderating effects of adult attachment in the association between extroversion and subjective well-being in Korea. A total of 334 students recruited from four universities in Korea completed self-reported questionnaires regarding extroversion, attachment, and subjective well-being. The results showed that the innate extroverted orientation of university students affected positive emotions only when the level of attachment avoidance was low. In contrast, although university students had an extroverted orientation, their extroversion did not have a significant influence on positive emotions when their level of attachment avoidance was high. The findings of this study suggest that high levels of attachment avoidance may prevent for extroverts from experiencing positive emotions.
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http://dx.doi.org/10.1177/0033294121991828DOI Listing
February 2021

Functional and structural characterization of Deinococcus radiodurans R1 MazEF toxin-antitoxin system, Dr0416-Dr0417.

J Microbiol 2021 Feb 1;59(2):186-201. Epub 2021 Feb 1.

Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.

In prokaryotes, toxin-antitoxin (TA) systems are commonly found. They likely reflect the adaptation of pathogenic bacteria or extremophiles to various unfavorable environments by slowing their growth rate. Genomic analysis of the extremophile Deinococcus radiodurans R1 revealed the presence of eight type II TA systems, including the genes dr0417, dr0660, dr1530, dr0690, and dr1807. Expression of these toxin genes led to inhibition of Escherichia coli growth, whereas their antidote antitoxins were able to recover the growth defect. Remarkably, Dr0417 (DrMazF) showed endoribonuclease activity toward rRNAs as well as mRNAs, as determined by in vivo and in vitro RNA cleavage assays, and this activity was inhibited by Dr0416 (DrMazE). It was also found that the expression of dr0416-0417 module is directly regulated by the DrMazE-MazF complex. Furthermore, this TA module was induced under stress conditions and plays an important role in survival. To understand the regulatory mechanism at the molecular level, we determined the first high-resolution structures of DrMazF alone and of the DrMazE-MazF complex. In contrast with the hetero-hexameric state of typical MazE-MazF complexes found in other species, DrMazE-MazF crystal structure consists of a hetero-trimer, with the DNA-binding domain of DrMazE undergoing self-cleavage at the flexible linker loop. Our structure revealed that the unique residue R54 provides an additional positive charge to the substrate-binding pocket of DrMazF, its mutation significantly affects the endonuclease activity. Thus, our work reports the unique structural and biochemical features of the DrMazE-MazF system.
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http://dx.doi.org/10.1007/s12275-021-0523-zDOI Listing
February 2021

Elucidation of a Novel Role of YebC in Surface Polysaccharides Regulation of -Deletion.

Front Microbiol 2020 9;11:597515. Epub 2020 Nov 9.

Microbiological Resource Research Institute, Pusan National University, Busan, South Korea.

The BipA (BPI-inducible protein A) protein is ubiquitously conserved in various bacterial species and belongs to the translational GTPase family. Interestingly, the function of BipA is not essential for cell growth under normal growth conditions. However, cultivation of -deleted cells at 20°C leads to cold-sensitive growth defect and several phenotypic changes in ribosome assembly, capsule production, and motility, suggesting its global regulatory roles. Previously, our genomic library screening revealed that the overexpressed ribosomal protein (r-protein) L20 partially suppressed cold-sensitive growth defect by resolving the ribosomal abnormality in -deleted cells at low temperature. Here, we explored another genomic library clone containing , which encodes a predicted transcriptional factor that is not directly associated with ribosome biogenesis. Interestingly, overexpression of in -deleted cells diminished capsule synthesis and partially restored lipopolysaccharide (LPS) core maturation at a low temperature without resolving defects in ribosome assembly or motility, indicating that YebC may be specifically involved in the regulation of exopolysaccharide and LPS core synthesis. In this study, we collectively investigated the impacts of -deletion on capsule, LPS, biofilm formation, and motility and revealed novel roles of YebC in extracellular polysaccharide production and LPS core synthesis at low temperature using this mutant strain. Furthermore, our findings suggest that ribosomal defects as well as increased capsule synthesis, and changes in LPS composition may contribute independently to the cold-sensitivity of -deleted cells, implying multiple regulatory roles of BipA.
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http://dx.doi.org/10.3389/fmicb.2020.597515DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7682190PMC
November 2020

Overexpressed L20 Rescues 50S Ribosomal Subunit Assembly Defects of -Deletion in .

Front Microbiol 2019 9;10:2982. Epub 2020 Jan 9.

Department of Microbiology, Pusan National University, Busan, South Korea.

The BipA (BPI-inducible protein A) protein is highly conserved in a large variety of bacteria and belongs to the translational GTPases, based on sequential and structural similarities. Despite its conservation in bacteria, is not essential for cell growth under normal growth conditions. However, at 20°C, deletion of causes not only severe growth defects but also several phenotypic changes such as capsule production, motility, and ribosome assembly, indicating that it has global regulatory properties. Our recent studies revealed that BipA is a novel ribosome-associating GTPase, whose expression is cold-shock-inducible and involved in the incorporation of the ribosomal protein (r-protein) L6. However, the precise mechanism of BipA in 50S ribosomal subunit assembly is not completely understood. In this study, to demonstrate the role of BipA in the 50S ribosomal subunit and possibly to find an interplaying partner(s), a genomic library was constructed and suppressor screening was conducted. Through screening, we found a suppressor gene, , encoding r-protein L20, which is assembled at the early stage of ribosome assembly and negatively regulates its own expression at the translational level. We demonstrated that the exogenous expression of restored the growth of -deleted strain at low temperature by partially recovering the defects in ribosomal RNA processing and ribosome assembly. Our findings suggest that the function of BipA is pivotal for 50S ribosomal subunit biogenesis at a low temperature and imply that BipA and L20 may exert coordinated actions for proper ribosome assembly under cold-shock conditions.
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http://dx.doi.org/10.3389/fmicb.2019.02982DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6962249PMC
January 2020

The GTPase BipA expressed at low temperature in assists ribosome assembly and has chaperone-like activity.

J Biol Chem 2018 11 10;293(47):18404-18419. Epub 2018 Oct 10.

From the Department of Microbiology, Pusan National University, Busan 46241, Korea. Electronic address:

BPI-inducible protein A (BipA) is a conserved ribosome-associated GTPase in bacteria that is structurally similar to other GTPases associated with protein translation, including IF2, EF-Tu, and EF-G. Its binding site on the ribosome appears to overlap those of these translational GTPases. Mutations in the gene cause a variety of phenotypes, including cold and antibiotics sensitivities and decreased pathogenicity, implying that BipA may participate in diverse cellular processes by regulating translation. According to recent studies, a -deletion strain of displays a ribosome assembly defect at low temperature, suggesting that BipA might be involved in ribosome assembly. To further investigate BipA's role in ribosome biogenesis, here, we compared and analyzed the ribosomal protein compositions of MG1655 WT and -deletion strains at 20 °C. Aberrant 50S ribosomal subunits ( 44S particles) accumulated in the -deletion strain at 20 °C, and the ribosomal protein L6 was absent in these 44S particles. Furthermore, expression was significantly stimulated at 20 °C, suggesting that it encodes a cold shock-inducible GTPase. Moreover, the transcriptional regulator cAMP receptor protein (CRP) positively promoted expression only at 20 °C. Importantly, GFP and α-glucosidase refolding assays revealed that BipA has chaperone activity. Our findings indicate that BipA is a cold shock-inducible GTPase that participates in 50S ribosomal subunit assembly by incorporating the L6 ribosomal protein into the 44S particle during the assembly.
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http://dx.doi.org/10.1074/jbc.RA118.002295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6254333PMC
November 2018

Functional Studies of Five Toxin-Antitoxin Modules in H37Rv.

Front Microbiol 2016 21;7:2071. Epub 2016 Dec 21.

Department of Microbiology, Pusan National University Busan, Republic of Korea.

Toxin-antitoxin (TA) systems, which consist of an intracellular toxin and its antidote (antitoxin), are encoded by ubiquitous genetic modules in prokaryotes. Commonly, the activity of a toxin is inhibited by its antitoxin under normal growth conditions. However, antitoxins are degraded in response to environmental stress, and toxins liberated from antitoxins consequently induce cell death or growth arrest. In free-living prokaryotes, TA systems are often present in large numbers and are considered to be associated with the adaptation of pathogenic bacteria or extremophiles to various unfavorable environments by shifting cells to a slow growth rate. Genomic analysis of the human pathogen H37Rv () revealed the presence of a large number of TA systems. Accordingly, we investigated five uncharacterized TA systems (Rv2019-Rv2018, Rv3697c-Rv3697A, Rv3180c-Rv3181c, Rv0299-Rv0298, and Rv3749c-Rv3750c) of . Among these, the expression of the Rv2019 toxin inhibited the growth of , and and this growth defect was recovered by the expression of the Rv2018 antitoxin. Interestingly, Rv3180c was toxic only in , whose toxicity was neutralized by Rv3181c antitoxin. and assays revealed the ribosomal RNA (rRNA) cleavage activity of the Rv2019 toxin. Moreover, mRNAs appeared to be substrates of Rv2019. Therefore, we concluded that the ribonuclease activity of the Rv2019 toxin triggers the growth defect in and that the Rv2018 antitoxin inhibits the ribonuclease activity of the Rv2019 toxin.
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http://dx.doi.org/10.3389/fmicb.2016.02071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5175181PMC
December 2016

First Phase I human clinical trial of a killed whole-HIV-1 vaccine: demonstration of its safety and enhancement of anti-HIV antibody responses.

Retrovirology 2016 Nov 28;13(1):82. Epub 2016 Nov 28.

Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1400 Western Road, London, ON, N6G 2V4, Canada.

Background: Vaccination with inactivated (killed) whole-virus particles has been used to prevent a wide range of viral diseases. However, for an HIV vaccine this approach has been largely negated due to inherent safety concerns, despite the ability of killed whole-virus vaccines to generate a strong, predominantly antibody-mediated immune response in vivo. HIV-1 Clade B NL4-3 was genetically modified by deleting the nef and vpu genes and substituting the coding sequence for the Env signal peptide with that of honeybee melittin signal peptide to produce a less virulent and more replication efficient virus. This genetically modified virus (gmHIV-1) was inactivated and formulated as a killed whole-HIV vaccine, and then used for a Phase I human clinical trial (Trial Registration: Clinical Trials NCT01546818). The gmHIV-1 was propagated in the A3.01 human T cell line followed by virus purification and inactivation with aldrithiol-2 and γ-irradiation. Thirty-three HIV-1 positive volunteers receiving cART were recruited for this observer-blinded, placebo-controlled Phase I human clinical trial to assess the safety and immunogenicity.

Results: Genetically modified and killed whole-HIV-1 vaccine, SAV001, was well tolerated with no serious adverse events. HIV-1-specific PCR showed neither evidence of vaccine virus replication in the vaccine virus-infected human T lymphocytes in vitro nor in the participating volunteers receiving SAV001 vaccine. Furthermore, SAV001 with adjuvant significantly increased the pre-existing antibody response to HIV-1 proteins. Antibodies in the plasma of vaccinees were also found to recognize HIV-1 envelope protein on the surface of infected cells as well as showing an enhancement of broadly neutralizing antibodies inhibiting tier I and II of HIV-1 B, D, and A subtypes.

Conclusion: The killed whole-HIV vaccine, SAV001, is safe and triggers anti-HIV immune responses. It remains to be determined through an appropriate trial whether this immune response prevents HIV infection.
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http://dx.doi.org/10.1186/s12977-016-0317-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5126836PMC
November 2016

Heterologous Expression of Der Homologs in an Escherichia coli der Mutant and Their Functional Complementation.

J Bacteriol 2016 09 11;198(17):2284-96. Epub 2016 Aug 11.

Department of Microbiology, Pusan National University, Busan, Republic of Korea

Unlabelled: The unique Escherichia coli GTPase Der (double Era-like GTPase), which contains tandemly repeated GTP-binding domains, has been shown to play an essential role in 50S ribosomal subunit biogenesis. The depletion of Der results in the accumulation of precursors of 50S ribosomal subunits that are structurally unstable at low Mg(2+) concentrations. Der homologs are ubiquitously found in eubacteria. Conversely, very few are conserved in eukaryotes, and none is conserved in archaea. In the present study, to verify their conserved role in bacterial 50S ribosomal subunit biogenesis, we cloned Der homologs from two gammaproteobacteria, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium; two pathogenic bacteria, Staphylococcus aureus and Neisseria gonorrhoeae; and the extremophile Deinococcus radiodurans and then evaluated whether they could functionally complement the E. coli der-null phenotype. Only K. pneumoniae and S Typhimurium Der proteins enabled the E. coli der-null strain to grow under nonpermissive conditions. Sucrose density gradient experiments revealed that the expression of K. pneumoniae and S Typhimurium Der proteins rescued the structural instability of 50S ribosomal subunits, which was caused by E. coli Der depletion. To determine what allows their complementation, we constructed Der chimeras. We found that only Der chimeras harboring both the linker and long C-terminal regions could reverse the growth defects of the der-null strain. Our findings suggest that ubiquitously conserved essential GTPase Der is involved in 50S ribosomal subunit biosynthesis in various bacteria and that the linker and C-terminal regions may participate in species-specific recognition or interaction with the 50S ribosomal subunit.

Importance: In Escherichia coli, Der (double Era-like GTPase) is an essential GTPase that is important for the production of mature 50S ribosomal subunits. However, to date, its precise role in ribosome biogenesis has not been clarified. In this study, we used five Der homologs from gammaproteobacteria, pathogenic bacteria, and an extremophile to elucidate their conserved function in 50S ribosomal subunit biogenesis. Among them, Klebsiella pneumoniae and Salmonella enterica serovar Typhimurium Der homologs implicated the participation of Der in ribosome assembly in E. coli Our results show that the linker and C-terminal regions of Der homologs are correlated with its functional complementation in E. coli der mutants, suggesting that they are involved in species-specific recognition or interaction with 50S ribosomal subunits.
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http://dx.doi.org/10.1128/JB.00384-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4984549PMC
September 2016

Marital satisfaction and maternal depressive symptoms among Korean mothers transitioning to parenthood.

Authors:
Eunsil Choi

J Fam Psychol 2016 06 14;30(4):516-21. Epub 2015 Dec 14.

Department of Family and Housing Studies.

Although many empirical findings support associations between marital satisfaction and depressive symptoms, gaps remain in our understanding of the magnitude and direction of the associations between marital satisfaction and depressive symptoms as well as the associations in a collectivistic culture. The present study examined autoregressive cross-lagged associations between marital satisfaction and maternal depressive symptoms across a 3-year investigation in a sample of Korean mothers transitioning to parenthood. The sample consisted of 2,078 mothers in the Panel Study of Korean Children. The mothers reported marital satisfaction and maternal depressive symptoms annually for 3 years. The results of an autoregressive cross-lagged model revealed bidirectional associations between marital satisfaction and maternal depressive symptoms. The findings provide evidence of an interactional model of depression in a sample of Korean mothers. (PsycINFO Database Record
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http://dx.doi.org/10.1037/fam0000178DOI Listing
June 2016

Inhibitory effect of UvrD and DinG on the replication of ColE1-derived plasmids in Escherichia coli.

Plasmid 2015 Sep 2;81:32-41. Epub 2015 Jul 2.

Department of Microbiology, Pusan National University, Busan, Republic of Korea. Electronic address:

CspA has been identified as a major cold-shock protein in Escherichia coli. CspA binds to RNAs which are abnormally folded at low temperature and then acts as an RNA chaperone unfolding those RNAs. The dramatic expression of cspA at low temperature is contributed by posttranscriptional stability and robust translatability. Interestingly, when cspA mRNA encoding a premature nonsense codon was overexpressed at low temperature, cell growth was completely inhibited. This phenotype was termed LACE (the low temperature-dependent antibiotic effect of truncated cspA expression), and this lethality resulted from exclusive stalling of most ribosomes on mutant cspA mRNAs. In a previous study, we demonstrated that overexpression of the ATP-dependent DNA helicases, UvrD and DinG, suppressed the lethality and ribosome stalling caused by mutant cspA mRNA. In the present study, we attempted to elucidate how these two DNA helicases help recover normal growth under LACE condition. Interestingly, we found that UvrD and DinG appeared to have an ability to down-regulate the replication of pUC-based high copy plasmid. In plasmid copy number tests, the amount of pUC-based plasmid encoding mutant cspA was reduced by 3-10-fold when either UvrD or DinG was expressed. Through a β-galactosidase activity assay, we also confirmed that expression of the lacZα gene inserted into the pUC-based plasmid was significantly reduced due to down-regulation of plasmid replication. Our findings imply that UvrD and DinG, known as non-replicative helicases, play a novel role in the regulation of ColE1-like plasmid replication.
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http://dx.doi.org/10.1016/j.plasmid.2015.06.002DOI Listing
September 2015

Statistical methods used in articles published by the Journal of Periodontal and Implant Science.

J Periodontal Implant Sci 2014 Dec 31;44(6):288-92. Epub 2014 Dec 31.

BK21 PLUS Program in Embodiment: Health-Society Interaction, Department of Public Health Sciences, Graduate School, Korea University, Seoul, Korea. ; Department of Health Policy and Management, College of Health Sciences, Korea University, Seoul, Korea.

Purpose: The purposes of this study were to assess the trend of use of statistical methods including parametric and nonparametric methods and to evaluate the use of complex statistical methodology in recent periodontal studies.

Methods: This study analyzed 123 articles published in the Journal of Periodontal & Implant Science (JPIS) between 2010 and 2014. Frequencies and percentages were calculated according to the number of statistical methods used, the type of statistical method applied, and the type of statistical software used.

Results: Most of the published articles considered (64.4%) used statistical methods. Since 2011, the percentage of JPIS articles using statistics has increased. On the basis of multiple counting, we found that the percentage of studies in JPIS using parametric methods was 61.1%. Further, complex statistical methods were applied in only 6 of the published studies (5.0%), and nonparametric statistical methods were applied in 77 of the published studies (38.9% of a total of 198 studies considered).

Conclusions: We found an increasing trend towards the application of statistical methods and nonparametric methods in recent periodontal studies and thus, concluded that increased use of complex statistical methodology might be preferred by the researchers in the fields of study covered by JPIS.
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http://dx.doi.org/10.5051/jpis.2014.44.6.288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284377PMC
December 2014

Effects of adult attachment and emotional distractors on brain mechanisms of cognitive control.

Psychol Sci 2010 Dec 22;21(12):1818-26. Epub 2010 Nov 22.

Department of Psychology, University of Illinois at Urbana-Champaign, 603 E Daniel St, Champaign, IL 61820, USA.

Using data from 34 participants who completed an emotion-word Stroop task during functional magnetic resonance imaging, we examined the effects of adult attachment on neural activity associated with top-down cognitive control in the presence of emotional distractors. Individuals with lower levels of secure-base-script knowledge--reflected in an adult's inability to generate narratives in which attachment-related threats are recognized, competent help is provided, and the problem is resolved--demonstrated more activity in prefrontal cortical regions associated with emotion regulation (e.g., right orbitofrontal cortex) and with top-down cognitive control (left dorsolateral prefrontal cortex, anterior cingulate cortex, and superior frontal gyrus). Less efficient performance and related increases in brain activity suggest that insecure attachment involves a vulnerability to distraction by attachment-relevant emotional information and that greater cognitive control is required to attend to task-relevant, nonemotional information. These results contribute to the understanding of mechanisms through which attachment-related experiences may influence developmental adaptation.
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http://dx.doi.org/10.1177/0956797610388809DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3056541PMC
December 2010