Publications by authors named "Myung Jin Lee"

49 Publications

Status of antimicrobial stewardship programmes in Korean hospitals including small to medium-sized hospitals and the awareness and demands of physicians: a nationwide survey in 2020.

J Glob Antimicrob Resist 2021 Jun 18;26:180-187. Epub 2021 Jun 18.

Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82 Gumi-ro, 173 beon-gil, Bundang-gu, Seongnam 13620, Gyeonggi-do, South Korea.

Objectives: This study aimed to identify the status of antimicrobial stewardship programmes (ASPs) in small to medium-sized Korean hospitals as well as the awareness and demands about ASPs of physicians.

Methods: A questionnaire was designed based on a questionnaire from a previous nationwide survey in 2018 targeting large hospitals in Korea and modified to reflect the results of in-depth interviews with non-infectious diseases (IDs) physicians at secondary care hospitals. The survey targeted all hospitals with ≥150 beds in South Korea and was performed in May-June 2020. Only one ASP-associated physician per hospital participated in the survey.

Results: The survey response rate was 31.9% (217/680). ID specialists comprised the majority of medical personnel participating in ASPs in tertiary care hospitals. Conversely, in secondary and primary care hospitals there was no predominant medical personnel for ASPs and the median full-time equivalent was 0 for all types of medical personnel. Tertiary care hospitals, more than secondary and primary care hospitals, tended to perform ASP activities more actively. 'Workforce for ASPs', 'Establishment of healthcare fees for ASPs' and 'Development of tools for ASPs' were the most important required support for ASP improvement.

Conclusion: The level of ASP establishment was more limited in primary care hospitals than in secondary and tertiary care hospitals in Korea. To improve ASPs in Korean hospitals, a supporting workforce and the establishment of a healthcare fee for ASPs appear to be necessary.
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http://dx.doi.org/10.1016/j.jgar.2021.06.001DOI Listing
June 2021

SARS-CoV-2-Specific Antibody and T Cell Response Kinetics According to Symptom Severity.

Am J Trop Med Hyg 2021 Jun 17. Epub 2021 Jun 17.

Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Data on the longevity of humoral and cell-mediated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients with coronavirus disease 2019 (COVID-19) are limited. We evaluated the detailed kinetics of antibody and T-cell responses at the acute, convalescent, and post-convalescent phases in COVID-19 patients with a wide range of severity. We enrolled patients with COVID-19 prospectively from four hospitals and one community treatment center between February 2020 and January 2021. symptom severity was classified as mild, moderate, or severe/critical. Patient blood samples were collected at 1 week (acute), 1 month (convalescent), and 2 months after symptom onset (post-convalescent). Human SARS-CoV-2 IgG and IgM antibodies were measured using in-house-developed ELISA. The SARS-CoV-2-specific T-cell responses against overlapping peptides of spike proteins and nucleoprotein were measured by interferon-γ enzyme-linked immunospot assays. Twenty-five COVID-19 patients were analyzed (mild, n = 5; moderate, n = 9; severe/critical, n = 11). IgM and IgG antibody responses peaked at 1 month after symptom onset and decreased at 2 months. IgG response levels were significantly greater in the severe/critical group compared with other groups. Interferon-γ-producing T-cell responses increased between 1 week and 1 month after symptom onset, and had a trend toward decreasing at 2 months, but did not show significant differences according to severity. Our data indicate that SARS-CoV-2-specific antibody responses were greater in those with severe symptoms and waned after reaching a peak around 1 month after symptom onset. However, SARS-CoV-2-specific T-cell responses were not significantly different according to symptom severity, and decreased slowly during the post-convalescent phase.
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http://dx.doi.org/10.4269/ajtmh.20-1594DOI Listing
June 2021

Role of Zinc-Doped Bioactive Glass Encapsulated with Microspherical Gelatin in Localized Supplementation for Tissue Regeneration: A Contemporary Review.

Molecules 2021 Mar 24;26(7). Epub 2021 Mar 24.

Department of Dental Hygiene, Division of Health Science, Baekseok University, Cheonan 31065, Korea.

Gelatin, a natural polymer, provides excellent tissue compatibility for use in tissue rehabilitation. Bioactive glasses (BAG) offer superior capacity in stimulating a bioactive response but show high variability in uptake and solubility. To tackle these drawbacks, a combination of gelatin with BAG is proposed to form composites, which then offer a synergistic response. The cross-linked gelatin structure's mechanical properties are enhanced by the incorporation of the inorganic BAG, and the rate of BAG ionic supplementation responsible for bioactivity and regenerative potential is better controlled by a protective gelatin layer. Several studies have demonstrated the cellular benefits of these composites in different forms of functional modification such as doping with zinc or incorporation of zinc such as ions directly into the BAG matrix. This review presents a comprehensive perspective on the individual characteristics of BAG and gelatin, including the synthesis and mechanism of action. Further, adaptation of the composite into various applications for bone tissue engineering is discussed and future challenges are highlighted.
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http://dx.doi.org/10.3390/molecules26071823DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8038022PMC
March 2021

Surface Characterization, Biocompatibility and Antifungal Efficacy of a Denture-Lining Material Containing Extracts.

Molecules 2021 Mar 7;26(5). Epub 2021 Mar 7.

Department of Dental Hygiene, Hanseo University, Seosan 31963, Chungcheongnam-do, Korea.

Herein, we investigated the surface characterization and biocompatibility of a denture-lining material containing extracts and its antifungal efficacy against . To achieve this, a denture-lining material containing various concentrations of extract and a control group without extract were prepared. The surface characterization and biocompatibility of the samples were investigated. In addition, the antifungal efficacy of the samples on was investigated using spectrophotometric growth and a LIVE/DEAD assay. The results revealed that there was no significant difference between the biocompatibility of the experimental and control groups ( > 0.05). However, there was a significant difference between the antifungal efficiency of the denture material on and that of the control group ( < 0.05), which was confirmed by the LIVE/DEAD assay. These results indicate the promising potential of the extract-containing denture-lining material as an antifungal dental material.
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http://dx.doi.org/10.3390/molecules26051440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7962000PMC
March 2021

Development of key quality indicators for appropriate antibiotic use in the Republic of Korea: results of a modified Delphi survey.

Antimicrob Resist Infect Control 2021 03 6;10(1):48. Epub 2021 Mar 6.

Division of Infectious Diseases, Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea.

Background: An effective antibiotic stewardship program relies on the measurement of appropriate antibiotic use, on which there is a lack of consensus. We aimed to develop a set of key quality indicators (QIs) for nationwide point surveillance in the Republic of Korea.

Methods: A systematic literature search of PubMed, EMBASE, and Cochrane Library (publications until 20th November 2019) was conducted. Potential key QIs were retrieved from the search and then evaluated by a multidisciplinary expert panel using a RAND-modified Delphi procedure comprising two online surveys and a face-to-face meeting.

Results: The 23 potential key QIs identified from 21 studies were submitted to 25 multidisciplinary expert panels, and 17 key QIs were retained, with a high level of agreement (13 QIs for inpatients, 7 for outpatients, and 3 for surgical prophylaxis). After adding up the importance score and applicability, six key QIs [6 QIs (Q 1-6) for inpatients and 3 (Q 1, 2, and 5) for outpatients] were selected. (1) Prescribe empirical antibiotic therapy according to guideline, (2) change empirical antibiotics to pathogen-directed therapy, (3) obtain culture samples from suspected infection sites, (4) obtain two blood cultures, (5) adapt antibiotic dosage to renal function, and (6) document antibiotic plan. In surgical prophylaxis, the QIs to prescribe antibiotics according to the guideline and initiate antibiotic therapy 1 h before incision were selected.

Conclusions: We identified key QIs to measure the appropriateness of antibiotic therapy to identify targets for improvement and to evaluate the effects of antibiotic stewardship intervention.
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http://dx.doi.org/10.1186/s13756-021-00913-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7937201PMC
March 2021

Durable Oral Biofilm Resistance of 3D-Printed Dental Base Polymers Containing Zwitterionic Materials.

Int J Mol Sci 2021 Jan 3;22(1). Epub 2021 Jan 3.

BK21 FOUR Project, Yonsei University College of Dentistry, Seoul 03722, Korea.

Poly(methyl methacralyate) (PMMA) has long been used in dentistry as a base polymer for dentures, and it is recently being used for the 3D printing of dental materials. Despite its many advantages, its susceptibility to microbial colonization remains to be overcome. In this study, the interface between 3D-printed PMMA specimens and oral salivary biofilm was studied following the addition of zwitterionic materials, 2-methacryloyloxyethyl phosphorylcholine (MPC) or sulfobetaine methacrylate (SB). A significant reduction in bacterial and biofilm adhesions was observed following the addition of MPC or SB, owing to their protein-repellent properties, and there were no significant differences between the two test materials. Although the mechanical properties of the tested materials were degraded, the statistical value of the reduction was minimal and all the properties fulfilled the requirements set by the International Standard, ISO 20795-2. Additionally, both the test materials maintained their resistance to biofilm when subjected to hydrothermal fatigue, with no further deterioration of the mechanical properties. Thus, novel 3D-printable PMMA incorporated with MPC or SB shows durable oral salivary biofilm resistance with maintenance of the physical and mechanical properties.
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http://dx.doi.org/10.3390/ijms22010417DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7795277PMC
January 2021

Development of a Bioactive Flowable Resin Composite Containing a Zinc-Doped Phosphate-Based Glass.

Nanomaterials (Basel) 2020 Nov 22;10(11). Epub 2020 Nov 22.

BK21 FOUR Project, Yonsei University College of Dentistry, Seoul 03722, Korea.

Flowable resins used for dental restoration are subject to biofilm formation. Zinc has antibacterial properties. Thus, we prepared a zinc-doped phosphate-based glass (Zn-PBG) to dope a flowable resin and evaluated the antibacterial activity of the composite against () to extrapolate the preventative effect toward secondary caries. The composites were prepared having 0 (control), 1.9, 3.8, and 5.4 wt.% Zn-PBG. The flexural strength, elastic modulus, microhardness, depth of cure, ion release, inhibition zone size, and number of colony-forming units were evaluated and analyzed using ANOVA. The flexural strength of the control was significantly higher than those of Zn-PBG samples ( < 0.05). However, all samples meet the International Standard, ISO 4049. The microhardness was not significantly different for the control group and 1.9 and 3.8 wt.% groups, but the 5.4 wt.% Zn-PBG group had a significantly lower microhardness ( < 0.05). Further, the composite resins increasingly released P, Ca, Na, and Zn ions with an increase in Zn-PBG content ( < 0.05). The colony-forming unit count revealed a significant reduction in viability ( < 0.05) with increase in Zn-PBG content. Therefore, the addition of Zn-PBG to flowable composite resins enhances antibacterial activity and could aid the prevention of secondary caries.
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http://dx.doi.org/10.3390/nano10112311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7700342PMC
November 2020

Factors of Severity in Patients with COVID-19: Cytokine/Chemokine Concentrations, Viral Load, and Antibody Responses.

Am J Trop Med Hyg 2020 12 27;103(6):2412-2418. Epub 2020 Oct 27.

Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

The severity of COVID-19 ranges from mild to critical diseases. However, limited data have been published on the detailed kinetics of viral load and host immune response throughout the disease course depending on disease severity. In this study, we comprehensively analyzed viral load, antibody responses to SARS-CoV-2, and cytokines/chemokines during the disease course, and identified the factors related to severity. Nasopharyngeal (NP) and plasma specimens were obtained from 31 patients with COVID-19 during hospitalization. Viral RNA in NP specimens was quantified by reverse transcription-PCR. Anti-SARS-CoV-2 antibodies and cytokines/chemokines in plasma specimens were analyzed by ELISA and cytometric bead array. The viral load in patients with COVID-19 peaked at the early stage of the disease and continuously decreased. Severe and critical cases showed higher viral load and prolonged viral shedding than asymptomatic and mild cases. Whereas plasma IgG was gradually increased and maintained during hospitalization, plasma IgM peaked at 3 weeks after symptom onset and dissipated. The antibody response in severe and critical cases was slightly delayed but stronger than those in others. High levels of interferon (IFN)-α, IFN-γ-induced protein-10, monokine induced by IFN-γ, and interleukin-6 at 5-10 days from symptom onset were associated with the severity of COVID-19. Our data indicate that high viral load in the respiratory tract and excessive production of cytokines and chemokines between 1 and 2 weeks from the symptom onset were significantly associated with the severity of COVID-19.
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http://dx.doi.org/10.4269/ajtmh.20-1110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7695090PMC
December 2020

Clinical Characteristics of COVID-19: Clinical Dynamics of Mild Severe Acute Respiratory Syndrome Coronavirus 2 Infection Detected by Early Active Surveillance.

J Korean Med Sci 2020 Aug 17;35(32):e297. Epub 2020 Aug 17.

Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.

Background: There is limited information describing the presenting characteristics and dynamic clinical changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosed in the early phase of illness. This study is a case series of patients with coronavirus disease 2019 (COVID-19) admitted to 11 hospitals in Korea.

Methods: Patients with confirmed SARS-CoV-2 infection by positive polymerase chain reaction (PCR) testing of respiratory specimens by active surveillance that were finally discharged between February 20 and April 30, 2020 were included. Patients were classified into mild and non-mild groups on initial admission according to oxygen demand and Sequential Organ Failure Assessment score, and the mild group was followed up and subgrouped into non-aggravation and aggravation groups.

Results: A total of 161 patients with SARS-CoV2 infection were enrolled. Among the mild group of 136 patients, 11.7% of patients experienced clinical aggravation during hospitalization, but there was no initial clinical parameter on admission predicting their aggravation. Fever (odds ratio [OR], 4.56), thrombocytopenia (OR, 12.87), fever (OR, 27.22) and lactate dehydrogenase (LDH) > 300 U/L (OR, 18.35), and CRP > 1 mg/dL (OR, 11.31) significantly indicated aggravation in the 1st, 2nd, 3rd, and 4th 5-day periods, respectively. PCR positivity lasted for a median of 22 days and 32 days after the onset of illness in the non-aggravation and aggravation groups, respectively.

Conclusion: Old age was associated with early severe presentation. Clinical aggravation among asymptomatic or mild patients could not be predicted initially but was heralded by fever and several laboratory markers during the clinical course.
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http://dx.doi.org/10.3346/jkms.2020.35.e297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7431284PMC
August 2020

Resin-Based Sealant with Bioactive Glass and Zwitterionic Material for Remineralisation and Multi-Species Biofilm Inhibition.

Nanomaterials (Basel) 2020 Aug 12;10(8). Epub 2020 Aug 12.

Department of Orthodontics, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul 03722, Korea.

Since pits and fissures are the areas most commonly affected by caries due to their structural irregularity, bioactive resin-based sealant (RBS) may contribute to the prevention of secondary caries. This study aims to investigate the mechanical, physical, ion-release, enamel remineralisation, and antibacterial capabilities of the novel RBS with bioactive glass (BAG) and 2-methacryloyloxyethyl phosphorylcholine (MPC). For the synthesis, 12.5 wt% BAG and 3 wt% MPC were incorporated into RBS. The contact angle, flexural strength, water sorption, solubility, and viscosity were investigated. The release of multiple ions relating to enamel remineralisation was investigated. Further, the attachments of bovine serum albumin, brain heart infusion broth, and on RBS were studied. Finally, the thickness and biomass of a human saliva-derived microsm biofilm model were analysed before aging, with static immersion aging and with thermocycling aging. In comparison to commercial RBS, BAG+MPC increased the wettability, water sorption, solubility, viscosity, and release of multiple ions, while the flexural strength did not significantly differ. Furthermore, RBS with MPC and BAG+MPC significantly reduced protein and bacteria adhesion and suppressed multi-species biofilm attachment regardless of the existence of aging and its type. The novel RBS has great potential to facilitate enamel remineralisation and suppress biofilm adhesion, which could prevent secondary dental caries.
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http://dx.doi.org/10.3390/nano10081581DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7466479PMC
August 2020

Analysis of the Antimicrobial, Cytotoxic, and Antioxidant Activities of Extracts.

Plants (Basel) 2020 Aug 4;9(8). Epub 2020 Aug 4.

Department of Dental Hygiene, Hanseo University, 46 Hanseo 1-ro, Haemi-myun, Seosan-si 31963, Korea.

This study analyzed the antimicrobial, cytotoxic, and antioxidant properties of (CO) extracts to confirm their antimicrobial activity toward oral microorganisms. The control group contained 0 μg/mL of CO, and the experimental groups contained 50, 100, 150, and 200 μg/mL of CO. To confirm the antibacterial activity of CO extracts against microorganisms in the oral cavity, an inhibition zone test, a colony-forming unit (CFU) analysis, an optical density (OD) evaluation, and a SEM (scanning electron microscopy) analysis were performed. A cytotoxicity test was also conducted to determine cell viability, and the contents of flavonoids and polyphenols were measured to analyze the extract components. In the control group, the growth inhibition zone increased, while the CFU and OD values decreased ( < 0.05). The SEM analysis confirmed that the number of microorganisms for both the microbes decreased. The cell viability was more than 80% in both the control and experimental groups, excluding the 200 μg/mL sample. The flavonoid and polyphenol contents in the experimental groups showed higher values than those of the control group. Therefore, the CO extract showed considerable antimicrobial activity toward both and , suggesting that it may be used as a natural antimicrobial agent for dental applications.
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http://dx.doi.org/10.3390/plants9080988DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463517PMC
August 2020

Improvement in the Microbial Resistance of Resin-Based Dental Sealant by Sulfobetaine Methacrylate Incorporation.

Polymers (Basel) 2020 Jul 30;12(8). Epub 2020 Jul 30.

Department of Orthodontics, Yonsei University College of Dentistry, Seoul 03722, Korea.

Prevention of dental caries is a key research area, and improvement of the pit and fissure sealants used for caries prevention has been of particular interest. This report describes results of incorporating a zwitterion, sulfobetaine methacrylate (SB), into photo-polymerized resin-based sealants to enhance resistance to cariogenic bacteria and protein adhesion. Varying amounts (1.5-5 wt%) of SB were incorporated into a resin-based sealant, and the flexural strength, wettability, depth of cure, protein adhesion, bacterial viability, and cell cytotoxicity of the resultant sealants were evaluated. The flexural strength decreased with the increasing SB content, but this decrease was statistically significant only for sealants containing ≥3 wt% SB. Incorporating a zwitterion led to a significant reduction in the water contact angle and protein adhesion. The colony-forming unit count showed a significant reduction in the bacterial viability of , which was confirmed with microscopic imaging. Moreover, cell cytotoxicity analysis of SB-modified sealants using an L929 fibroblast showed a cytotoxicity comparable to that of an unmodified control, suggesting no adverse effects on the cellular metabolism upon SB introduction. Hence, we conclude that the addition of 1.5-3 wt% SB can significantly enhance the inherent ability of sealants to resist adhesion and prevent dental caries.
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http://dx.doi.org/10.3390/polym12081716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463993PMC
July 2020

Antimicrobial Effects against Oral Pathogens and Cytotoxicity of Extract.

Plants (Basel) 2020 Jul 3;9(7). Epub 2020 Jul 3.

Department of Dental Hygiene, Hanseo University, Chungcheongnam-do 31962, Korea.

We aimed to evaluate the antimicrobial effects of extract on and and its biocompatibility for dental applications. The antimicrobial activity of the extracts at concentrations of 50, 100, 150, and 200 µg/mL was assessed using agar disk diffusion tests, counting the total number of colony-forming units (CFUs), spectrophotometric growth inhibitory assays, and microbial morphology observations using scanning electron microscopy (SEM; Merin, Carl Zeiss, Oberkochen, Germany). We measured the polyphenol and flavonoid contents of extracts using ultraviolet-visible spectrometry and the cytotoxicity of these extracts using an MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. We identified that extracts had significant antimicrobial effects against and . The optical density of the experimental groups significantly decreased compared with that of the control group. SEM images revealed that the extract affected the morphology and density of and . The extract concentration of flavonoids, but not polyphenols, increased with increasing concentrations of the extract. Furthermore, cell viabilities were more than 70% for extracts with concentrations of 50 and 100 μg/mL. Naturally derived is biocompatible and exhibits an excellent antimicrobial effect against oral pathogens such as and . Thus, extracts can be used for the development of oral products that treat and prevent oral diseases.
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http://dx.doi.org/10.3390/plants9070838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7412329PMC
July 2020

Comparison of the Seroprevalence of Measles Antibodies among Healthcare Workers in Two Korean Hospitals in 2019.

Infect Chemother 2020 Mar 21;52(1):93-97. Epub 2020 Jan 21.

Department of Internal Medicine, Inje University Sanggye Paik Hospital, Seoul, Korea.

We performed a point seroprevalence survey of measles among healthcare workers (HCWs) at two Korean teaching hospitals in 2019. A total of 2,830 HCWs underwent an antibody test. The overall seropositivity of measles was 93.1%. The seroprevalence of measles was lowest in HCWs aged 20 - 24 years (81.2%), followed by those aged 25 - 29 years (90.1%). The rates of anti-measles IgG positivity were significantly different between the two hospitals (97.0% vs. 89.4%, <0.001). These results suggest that the seropositivity of measles in HCWs may differ depending on the hospital's vaccination policy.
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http://dx.doi.org/10.3947/ic.2020.52.1.93DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7113453PMC
March 2020

Quantitative Interpretation of Hydration Dynamics Enabled the Fabrication of a Zwitterionic Antifouling Surface.

ACS Appl Mater Interfaces 2020 Feb 4;12(7):7951-7965. Epub 2020 Feb 4.

Department of Chemical & Biomolecular Engineering, College of Engineering , Yonsei University , 50 Yonsei-ro, Seodaemun-gu , Seoul 03722 , Republic of Korea.

In the medical industry, zwitterionic brushes have received significant attention owing to their antifouling effect that arose from their hydration ability. However, sufficient understanding of the hydration dynamics of zwitterionic brushes is required to fabricate the precisely controlled antifouling medical devices. In this paper, we successfully show that hydration, the interaction between water molecules and zwitterionic brushes, and its dynamics can be evaluated logically and quantitatively using (i) water contact angle, (ii) molecular dynamics simulation, and (iii) Raman spectroscopy. Based on the intuitive results on hydration, we precisely optimized the antifouling property of the model medical device, a removable orthodontic retainer, with various grafting efficiencies of 2-methacryloyloxyethyl phosphate choline. As a result, the model device reduced nonspecific adsorption of proteins and bacteria, indicating an improved antifouling effect, and also inhibited the formation of a biofilm. Furthermore, the device showed excellent physical properties desirable for application in the orthodontic field, meaning the balance between the antibacterial property and mechanical strength.
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http://dx.doi.org/10.1021/acsami.9b21566DOI Listing
February 2020

Novel Dental Poly (Methyl Methacrylate) Containing Phytoncide for Antifungal Effect and Inhibition of Oral Multispecies Biofilm.

Materials (Basel) 2020 Jan 13;13(2). Epub 2020 Jan 13.

Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul 03722, Korea.

Despite the many advantages of poly (methyl methacrylate) (PMMA) as a dental polymer, its antifungal and antibacterial effects remain limited. Here, phytoncide was incorporated into PMMA to inhibit fungal and biofilm accumulation without impairing the basic and biological properties of PMMA. A variable amount of phytoncide (0 wt % to 5 wt %) was incorporated into PMMA, and the basic material properties of microhardness, flexural strength and gloss were evaluated. In addition, cell viability was confirmed by MTT assay. This MTT assay measures cell viability via metabolic activity, and the color intensity of the formazan correlates viable cells. The fungal adhesion and viability on the PMMA surfaces were evaluated using (a pathogenic yeast). Finally, the thickness of saliva-derived biofilm was estimated. The flexural strength of PMMA decreased with increasing phytoncide contents, whereas there were no significant differences in the microhardness and gloss ( > 0.05) and the cell viability ( > 0.05) between the control and the phytoncide-incorporated PMMA samples. The amounts of adherent colony-forming unit (CFU) counts, and saliva-derived biofilm thickness were significantly lower in the phytoncide-incorporated PMMA compared to the control ( < 0.05). Hence, it was concluded that the incorporation of appropriate amounts of phytoncide in PMMA demonstrated antifungal effects while maintaining the properties, which could be a possible use in dentistry application such as denture base resin.
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http://dx.doi.org/10.3390/ma13020371DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7014161PMC
January 2020

Incorporation of zwitterionic materials into light-curable fluoride varnish for biofilm inhibition and caries prevention.

Sci Rep 2019 12 20;9(1):19550. Epub 2019 Dec 20.

Department of Orthodontics, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Republic of Korea.

We incorporated zwitterionic materials into light-curable fluoride varnish (LCFV) in order to inhibit biofilm accumulation and prevent dental caries, and the properties of LCFV with three different zwitterionic materials, namely, 2-methacryloyloxyethyl phosphorylcholine (MPC), carboxybetaine methacrylate (CBMA), and sulfobetaine methacrylate (SBMA) polymers (each at a weight percentage of 3%), were compared; unmodified LCFV without any zwitterionic material was used as a control. Material properties including film thickness and degree of conversion (DC) of each type of LCFV were evaluated. In addition, protein-repellent effects and inhibitory effects on Streptococcus mutans adhesion and saliva-derived biofilm accumulation of LCFV were estimated. Finally, the preventive effect of LCFV on enamel demineralization was assessed in vitro on extracted human teeth specimens stored in S. mutans-containing medium. The film thickness of LCFV significantly decreased with the incorporation of zwitterionic materials compared to the control LCFV, whereas there were no significant differences in the DC among all of the LCFV groups. Furthermore, the amount of adsorbed protein, adherent S. mutans colony-forming unit (CFU) counts, and saliva-derived biofilm thickness and biomass were all significantly lower for LCFV with incorporated zwitterionic materials compared with the control. All LCFV groups including the control showed certain preventive effects against enamel demineralization during a 14-day immersion in the medium with S. mutans and sucrose, and the depth of demineralization was significantly lower in LCFV with zwitterionic materials than in the control. Thus, the incorporation of zwitterionic materials such as MPC, CBMA, and SBMA appears to confer superior antifouling effects to LCFV.
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http://dx.doi.org/10.1038/s41598-019-56131-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6925265PMC
December 2019

Bioactive resin-based composite with surface pre-reacted glass-ionomer filler and zwitterionic material to prevent the formation of multi-species biofilm.

Dent Mater 2019 09 16;35(9):1331-1341. Epub 2019 Jul 16.

Department of Orthodontics, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Republic of Korea; BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea. Electronic address:

Objective: This study evaluated the synergetic effect between surface pre-reacted glass-ionomer (SPRG) filler and 2-methacryloyloxyethyl phosphorylcholine (MPC), for inhibiting multi-species biofilm formation, while maintaining or even improving the original beneficial features of SPRG-filled resin-based composite (RBC).

Methods: MPC (1.5-10wt%) was incorporated into commercial SPRG-filled RBC. Then, the inherent properties of RBC, and ion release and acid-neutralising properties associated with SPRG were investigated. Further, protein adsorptions and bacterial adhesion and viability on the SPRG-filled RBC surfaces were studied using four kinds of oral bacteria; Streptococcus mutans, Actinomyces naeslundii, Veillonella parvula, and Porphyromonas gingivalis. Finally, the thickness and biomass of the human saliva-derived biofilm model cultured on test and control samples were analysed.

Results: Addition of MPC content resulted in decreased flexural strength and wettability of SPRG-filled RBC. SPRG-filled RBC released significantly higher amounts of multiple ions as contents of MPC increased. Meanwhile, SPRG-filled RBC with 5-wt% MPC significantly improved acid-neutralising properties than those of other test and control samples (P<0.001). SPRG-filled RBC with 3wt% MPC significantly reduced the amount of adsorbed bovine serum albumin and proteins from the brain heart infusion medium as compared to the control (P<0.01). A similar trend was observed in the attachment of four types of bacteria and multi-species biofilm (P<0.01).

Significance: Despite limitation in terms of deteriorations of some physical properties, addition of 3% MPC to SPRG-filled RBC leads to inhibition of the attachment of multi-species bacteria on its surface, as well as inhibition of biofilm growth. Moreover, the original important bioactive features of SPRG-filled RBC such as ion release and acid neutralisations are either maintained or improved upon adding MPC.
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http://dx.doi.org/10.1016/j.dental.2019.06.004DOI Listing
September 2019

The antibacterial effect of non-thermal atmospheric pressure plasma treatment of titanium surfaces according to the bacterial wall structure.

Sci Rep 2019 02 13;9(1):1938. Epub 2019 Feb 13.

BK21 PLUS Project, Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul, 03722, Korea.

Titanium is commonly used as a biomaterial for dental implants. In this study, we investigated the antibacterial properties of titanium samples following treatment with a non-thermal atmospheric pressure plasma jet (NTAPPJ) on bacteria with two different cell wall structures, including gram-positive and gram-negative bacteria. The hydrophilicity and surface energy of titanium surfaces were significantly increased after NTAPPJ treatment without altering topographical features. Changes in the chemical composition and reductive potential were observed on the NTAPPJ-treated titanium surfaces. The adhesion and biofilm formation rate of bacteria were significantly reduced on the NTAPPJ-treated titanium surfaces compared with the untreated samples, which was confirmed by fluorescent imaging. Regarding the comparison between gram-positive and gram-negative bacteria, both adhesion and the biofilm formation rate were significantly lower for gram-negative bacteria than gram-positive bacteria on samples treated for longer durations with the NTAPPJ. Transmission electron microscopy imaging showed a comparably more disruptive membrane structure of gram-negative bacteria than gram-positive bacteria on the NTAPPJ-treated surfaces. Our results indicated that the NTAPPJ treatment could be useful for preventing bacterial adhesion and biofilm formation on titanium dental implant surfaces, while the reductive potential on surfaces treated by the NTAPPJ could cause oxidation of bacteria, which could be more sensitive to gram-negative bacteria due to differences in the cell wall structure.
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http://dx.doi.org/10.1038/s41598-019-39414-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6374442PMC
February 2019

Novel anti-biofouling light-curable fluoride varnish containing 2-methacryloyloxyethyl phosphorylcholine to prevent enamel demineralization.

Sci Rep 2019 02 5;9(1):1432. Epub 2019 Feb 5.

Department of Orthodontics, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Republic of Korea.

We evaluated the efficacy of light-curable fluoride varnish (LCFV) that contains 2-methacryloyloxyethyl phosphorylcholine (MPC) in terms of anti-biofouling properties and prevention of tooth enamel demineralization. MPC was mixed with and incorporated into LCFV at 0 (control), 1.5, 3.0, 5.0, 10.0, 20.0, and 40.0 weight percentage (wt%). Addition of high wt% of MPC resulted in increased film thickness and decreased the degree of conversion, indicating loss of the advantageous properties of LCFV. Addition of 1.5, 3, or 5 wt% MPC significantly reduced the amount of bovine serum albumin adsorbed from a solution and proteins adsorbed from brain heart infusion medium compared to the control (P < 0.001). A similar pattern was observed for bacterial adhesion: significantly less Streptococcus mutans cells adhered on the surface of LCFV with 1.5, 3, or 5 wt% MPC (P < 0.001) than on the control, and similar results were obtained for Actinomyces naeslundii and Streptococcus sanguinis adherence to LCFV with 3 wt% MPC. Finally, bacterial adhesion, surface microhardness loss, and the depth of demineralization were substantially lower on bovine tooth enamel surface coated with LCFV containing 3 wt% of MPC than in the control treatment (0 wt% MPC). Therefore, this novel LCFV containing a low concentration of MPC (e.g., 3 wt%) would be effective in anti-biofouling while maintaining the important advantageous features of light-curable fluoride in preventing demineralization.
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http://dx.doi.org/10.1038/s41598-018-38255-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6363795PMC
February 2019

Novel anti-biofouling bioactive calcium silicate-based cement containing 2-methacryloyloxyethyl phosphorylcholine.

PLoS One 2019 17;14(1):e0211007. Epub 2019 Jan 17.

Department of Orthodontics, Institute of Craniofacial Deformity, Yonsei University College of Dentistry, Seoul, Republic of Korea.

Calcium silicate-based cements (CSCs) are commonly used for endodontic procedures; however, their antibacterial effects are limited. The objective of this study was to develop a 2-methacryloyloxyethyl phosphorylcholine (MPC)-incorporated CSC with improved antibacterial properties, while maintaining the original advantageous features of CSC. MPC was incorporated into a commercial CSC (Endocem MTA) at 0 wt% (control), 1.5%, 3.0 wt%, 5.0 wt%, 7.5 wt%, and 10 wt%. The setting time, compressive strength, water sorption, and glycerol contact angle were measured. Protein absorption was measured and bacterial adhesion on the surface was evaluated using Enterococcus faecalis. The bactericidal effect was examined by the disc diffusion test. Mineralization ability was assessed based on calcium ion deposition, as assessed by alizarin red staining, after immersion into Hank's balanced salt solution for 7 days. High concentrations of MPC in CSC (7.5 wt% and 10 wt%) increased the setting time, reduced compressive strength, and reduced wettability. MPC (3 wt%) had greater protein repellent and anti-biofouling effects than those of control and test materials (P < 0.001). However, no bactericidal effect was observed for any control or test materials. There was greater calcium ion deposition on the surface of MPC-supplemented CSC than on the control (P < 0.001). The addition of 3 wt% MPC polymer to CSC confers protein-repellent properties and reduced bacterial attachment, with the potential for improved mineralization.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0211007PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336247PMC
October 2019

Severe Fever with Thrombocytopenia Syndrome Patients with Hemophagocytic Lymphohistiocytosis Retrospectively Identified in Korea, 2008-2013.

J Korean Med Sci 2018 Dec 16;33(50):e319. Epub 2018 Nov 16.

Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.

The incidence of severe fever with thrombocytopenia syndrome (SFTS) has increased in Korea since a first report in 2013. We investigated whether SFTS existed before 2013 using real-time reverse transcription polymerase chain reaction and stored blood samples from febrile patients with thrombocytopenia. Four cases of SFTS were identified, with the earliest occurring in 2008.
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http://dx.doi.org/10.3346/jkms.2018.33.e319DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6281956PMC
December 2018

Changes in the physical properties and color stability of aesthetic restorative materials caused by various beverages.

Dent Mater J 2019 Feb 5;38(1):33-40. Epub 2018 Oct 5.

Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University.

This study investigates the effects of various beverages on the wettability, microhardness, and color stability of aesthetic dental restorative materials. A contact angle analyzer, Vickers hardness tester, and spectrophotometer were used to characterize the properties of the materials and a total of 225 specimens were prepared: 75 each for a resin composite, compomer, and giomer. Ingestion of energy drinks and cola caused the greatest deterioration in wettability and microhardness, and coffee caused the most significant color change. In addition, the change in the resin composite was lower than that of the other restorative materials. The extent of change in the restorative materials increased with duration and frequency of contact with the beverages, so a reduction in the frequency of ingestion of these beverages is recommended.
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http://dx.doi.org/10.4012/dmj.2017-247DOI Listing
February 2019

Ultrasonographic Findings of Scleredema Adultorum of Buschke Involving the Posterior Neck.

Korean J Radiol 2018 May-Jun;19(3):425-430. Epub 2018 Apr 6.

Department of Pathology, Dong-A University College of Medicine, Busan 49201, Korea.

Objective: To describe the clinical and ultrasonographic (US) findings in patients with scleredema adultorum of Buschke, who presented with sclerotic skin on their posterior neck.

Materials And Methods: After obtaining IRB approval, eight patients with scleredema adultorum of Buschke were enrolled. They underwent US examination of their posterior neck. The diagnoses were confirmed pathologically. The clinical history and US images were evaluated retrospectively. Dermal thickness was compared between the patient group and the age- and sex-matched control group.

Results: The patients included seven males and one female with a mean age of 51.5 years. All patients presented with thickening of the skin and/or a palpable mass on the posterior neck. Five (62.5%) of the eight patients showed erythematous discoloration. Six patients (75.0%) had a history of diabetes. The Hemoglobin A1c level was found to be increased in all patients. US images did not show any evidence of a soft tissue mass or infection. The mean dermal thickness in patients (7.01 ± 1.95 mm) was significantly greater than that in the control group (3.08 ± 0.87 mm) ( = 0.001). Multiple strong echogenic spots in the dermis were seen in all patients. Seven patients (87.5%) showed posterior shadowing in the lower dermis.

Conclusion: When a patient with a history of diabetes presents with a palpable mass or erythematous discoloration of the posterior neck and US shows the following imaging features: 1) no evidence of a soft tissue mass or infection, 2) thickening of the dermis, 3) multiple strong echogenic spots and/or posterior shadowing in the dermis, scleredema adultorum of Buschke should be considered in the differential diagnosis.
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http://dx.doi.org/10.3348/kjr.2018.19.3.425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5904469PMC
February 2019

Detection of waterborne norovirus genogroup I strains using an improved real time RT-PCR assay.

Arch Virol 2017 Nov 4;162(11):3389-3396. Epub 2017 Aug 4.

Department of Microbiology, College of Medicine, The Catholic University of Korea, 222, Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea.

Noroviruses (NoVs) are the major global source of acute gastroenteritis (AGE) outbreaks. To detect NoVs, real-time reverse transcription-quantitative PCR (RT-qPCR) assays have been widely employed since the first decade of the 21 century. We developed a redesigned probe, JJV1PM, for RT-qPCR assay detection of NoV genogroup (G) I strains. The new RT-qPCR assay using the JJV1PM-probe showed broader strain reactivity for 10 NoV GI genotypes, while the old method, using the JJV1PT-probe assay, detected only 7 NoV GI genotypes in a validation panel using human fecal specimens. The improved RT-qPCR assay was also successfully applied to water samples. The JJV1PM-probe assay identified 7 NoV GI genotypes, whereas the JJV1PT-probe assay detected only 2 NoV GI genotypes from water samples. Notably, groundwater-borne NoV GI strains detected by the improved JJV1PM-probe assay were associated with groundwater-borne AGE outbreaks in South Korea. The results of this study underscore the importance of the evaluation of RT-qPCR assays using recently circulating NoV strains prior to field application.
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http://dx.doi.org/10.1007/s00705-017-3505-zDOI Listing
November 2017

Cytotoxicity of Light-Cured Dental Materials according to Different Sample Preparation Methods.

Materials (Basel) 2017 Mar 14;10(3). Epub 2017 Mar 14.

Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, Seoul 03722, Korea.

Dental light-cured resins can undergo different degrees of polymerization when applied in vivo. When polymerization is incomplete, toxic monomers may be released into the oral cavity. The present study assessed the cytotoxicity of different materials, using sample preparation methods that mirror clinical conditions. Composite and bonding resins were used and divided into four groups according to sample preparation method: uncured; directly cured samples, which were cured after being placed on solidified agar; post-cured samples were polymerized before being placed on agar; and "removed unreacted layer" samples had their oxygen-inhibition layer removed after polymerization. Cytotoxicity was evaluated using an agar diffusion test, MTT assay, and confocal microscopy. Uncured samples were the most cytotoxic, while removed unreacted layer samples were the least cytotoxic ( < 0.05). In the MTT assay, cell viability increased significantly in every group as the concentration of the extracts decreased ( < 0.05). Extracts from post-cured and removed unreacted layer samples of bonding resin were less toxic than post-cured and removed unreacted layer samples of composite resin. Removal of the oxygen-inhibition layer resulted in the lowest cytotoxicity. Clinicians should remove unreacted monomers on the resin surface immediately after restoring teeth with light-curing resin to improve the restoration biocompatibility.
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http://dx.doi.org/10.3390/ma10030288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5503327PMC
March 2017

antiviral activity of ribavirin against severe fever with thrombocytopenia syndrome virus.

Korean J Intern Med 2017 Jul 30;32(4):731-737. Epub 2016 Nov 30.

Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.

Background/aims: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus. As yet, there is no effective antiviral therapy for SFTS. Ribavirin is a broad-spectrum antiviral agent, which has been tried for treatment of SFTS. In this study, antiviral activity of ribavirin against SFTSV has been investigated.

Methods: Vero cell-grown SFTSV strain Gangwon/Korea/2012 was treated with ribavirin at various concentrations. Antiviral activity of ribavirin was evaluated by inhibition of the SFTSV cytopathic effect in Vero cells and quantification of viral RNA load in culture supernatant using one-step real-time reverse transcription polymerase chain reaction. Cytotoxicity of ribavirin was determined by a tetrazolium-based colorimetric method.

Results: Ribavirin reduced SFTSV titers in a dose-dependent manner, with a half-maximal inhibitory concentration ranged from 3.69 to 8.72 μg/mL. Cytopathic effects were reduced as ribavirin concentration increased. No significant cytotoxicity was detected at ribavirin concentrations of ≤ 31.3 μg/mL.

Conclusions: Ribavirin exhibited inhibitory activity against SFTSV replication , which suggests that ribavirin can be used as a potential antiviral agent for SFTS.
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http://dx.doi.org/10.3904/kjim.2016.109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5511939PMC
July 2017

The effect of 4-hexylresorcinol on xenograft degradation in a rat calvarial defect model.

Maxillofac Plast Reconstr Surg 2016 Dec 5;38(1):29. Epub 2016 Aug 5.

Department of Oral Microbiology, College of Dentistry, Gangneung-Wonju National University, 7 Jukhyun-gil, Gangneung, 25457 Republic of Korea.

Background: The objective of this study was to evaluate xenograft degradation velocity when treated with 4-hexylresorcinol (4HR).

Methods: The scapula of a cow was purchased from a local grocery, and discs (diameter 8 mm, thickness 1 mm) were prepared by trephine bur. Discs treated with 4HR were used as the experimental group. Untreated discs were used as the control. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), antibacterial test, endotoxin test, and scanning electron microscopy (SEM) were performed on the discs. In vivo degradation was evaluated by the rat calvarial defect model.

Results: The XRD and FT-IR results demonstrated successful incorporation of 4HR into the bovine bone. The experimental disc showed antibacterial properties. The endotoxin test yielded results below the level of endotoxin contamination. In the SEM exam, the surface of the experimental group showed needle-shaped crystal and spreading of RAW264.7 cells. In the animal experiments, the amount of residual graft was significantly smaller in the experimental group compared to the control group ( = 0.003).

Conclusions: In this study, 4HR was successfully incorporated into bovine bone, and 4HR-incorporated bovine bone had antibacterial properties. In vivo experiments demonstrated that 4HR-incorporated bovine bone showed more rapid degradation than untreated bovine bone.
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http://dx.doi.org/10.1186/s40902-016-0076-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974267PMC
December 2016

How to improve the continuing professional development in Korea.

Authors:
Myung Jin Lee

Korean J Med Educ 2016 Jun 27;28(2):153-6. Epub 2016 May 27.

Korean Medical Ethics Study Group.

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http://dx.doi.org/10.3946/kjme.2016.27DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4951743PMC
June 2016

Subacute progressive disseminated histoplasmosis in immunocompetent patient.

Korean J Intern Med 2016 Sep 22;31(5):999-1002. Epub 2016 Feb 22.

Department of Pathology, Seoul National University Bundang Hospital, Seongnam, Korea.

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http://dx.doi.org/10.3904/kjim.2015.069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5016276PMC
September 2016