Yong Ju Lee

Konkuk University, Sŏul, Seoul, South Korea

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Publications (8)12.15 Total impact

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    ABSTRACT: This study was performed to develop a predictive growth model of Listeria monocytogenes to ensure the safety of raw pork. The pork samples were inoculated with a cocktail of two L. monocytogenes strains ATCC 15313 and L13-2 isolated from pork and were stored at 5, 15, and 25 °C. Results were evaluated using the MicroFit program. To develop primary models, the Baranyi, modified Gompertz, and Logistic model equations were applied to the observed data. The mathematically predicted growth rate parameters were evaluated using the coefficient of determination (R2), bias factor (Bf), accuracy factor (Af), and mean square error (MSE). The Baranyi model, which showed an R2 of 0.998 and MSE of 0.006, was more suitable than the modified Gompertz and Logistic models. In validation study of secondary model, it appeared that MSE's of specific growth rate (SGR) and lag time (LT) were relatively accurate and suitable for modeling the growth of L. monocytogenes. These values indicated that the developed models were acceptable for expressing the growth of microorganisms on raw pork, which can be applied to ensure the safety of meats and to establish standards for avoiding microbial contamination.
    Food Control 10/2014; 44:16–21. · 2.74 Impact Factor
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    ABSTRACT: The identification of novel diagnostic markers of pathogenic bacteria is essential for improving the accuracy of diagnoses and for developing targeted vaccines. Streptococcus pneumoniae is a significant human pathogenic bacterium that causes pneumonia. N-acetylglucosamine-6-phosphate deacetylase (NagA) was identified in a protein mixture secreted by S. pneumoniae and its strong immunogenicity was confirmed in an immuno-proteomic assay against the anti-serum of the secreted protein mixture. In this study, recombinant S. pneumoniae NagA protein was expressed and purified to analyze its protein characteristics, immunospecificity, and immunogenicity, thereby facilitating its evaluation as a novel diagnostic marker for S. pneumoniae. Mass spectrometry analysis showed that S. pneumoniae NagA contains four internal disulfide bonds and that it does not undergo post-translational modification. S. pneumoniae NagA antibodies successfully detected NagA from different S. pneumoniae strains, whereas NagA from other pathogenic bacteria species was not detected. In addition, mice infected with S. pneumoniae generated NagA antibodies in an effective manner. These results suggest that NagA has potential as a novel diagnostic marker for S. pneumoniae because of its high immunogenicity and immunospecificity.
    The Journal of Microbiology 10/2013; 51(5):659-64. · 1.28 Impact Factor
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    ABSTRACT: Objective: We aimed to evaluate the association between eosinophilic inflammation in induced sputum and pulmonary function and persistent airflow limitation in children. Methods: A total of 92 asthmatic children and 72 controls were enrolled in this study. Eosinophil count (%) and eosinophil cationic protein (ECP) levels were measured in induced sputum. We performed spirometry and a methacholine challenge test and measured total eosinophil count, total serum IgE, and serum ECP in all subjects. Results: Asthmatic children had significantly higher levels of sputum eosinophils (9% vs. 0%; P < 0.001) and sputum ECP (2.3 ± 0.7 vs. 1.6 ± 0.6 log μg/L, P < 0.001) than controls. Sputum ECP levels showed a significant negative correlation with postbronchodilator (postBD) FEV(1) (r = -0.307; P = 0.001) and postBD FEV1/FVC (r = -0.286; P = 0.002), whereas sputum eosinophils showed no correlation with postBD FEV(1) and postBD FEV(1)/FVC. However, no significant differences in sputum ECP and sputum eosinophil counts were observed in asthmatic children with and without persistent airflow limitation. Conclusions: Our findings suggest that sputum eosinophilic inflammation, especially ECP, is associated with pulmonary function and persistent airflow limitation, which is manifested by low postBD FEV(1)/FVC.
    Journal of Asthma 02/2013; · 1.85 Impact Factor
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    ABSTRACT: The antimicrobial effect of the methanol extract of Inula britannica flowers against methicillin resistant Staphylococcus aureus (MRSA) was investigated. It was confirmed that the methanol extract is mainly composed of quercetin, which has antimicrobial properties. The antimicrobial effect of the methanol extract against 3 MRSA strains was determined by the disc diffusion method. The minimal inhibitory concentrations were ranged from 0.625 mg/ml to 1.25 mg/ml, and the minimum bactericidal concentrations were 2.5 mg/ml. Time kill kinetics revealed bactericidal activities, and the morphological alterations in S. aureus ATCC 33591 treated with the extract were observed using a scanning electron microscope. The methanol extract affected the expression of the resistant genes, mecA, mecI, and mecRI in mRNA. Therefore, the methanol extract of I. britannica flowers clearly demonstrated an antimicrobial effect against MRSA and these results suggest a potential for application as a natural antimicrobial agent.
    Korean Journal of Microbiology and Biotechnology 01/2013; 41(3).
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    ABSTRACT: AIM: Asthma is a heterogeneous and complex chronic inflammatory disease of the airways. Asthma can be classified as eosinophilic asthma (EA) or noneosinophilic asthma (NEA). We investigated whether children with EA manifest different clinical characteristics than those with NEA. METHODS: We enrolled 288 steroid-naive asthmatic children and classified them, based on the cell counts in induced sputum, into EA (158 children) and NEA (89 children) groups. RESULTS: No significant differences were observed between the groups with regard to age, sex, family history of atopy, secondary smoking or asthma exacerbations. Moderate-to-severe asthma was more frequent in the EA group than in the NEA group. Blood eosinophil counts and serum eosinophil cationic protein were higher in EA patients than in NEA patients. The forced expiratory volume in 1 sec was lower in children with EA than in those with NEA (% of predicted value, 88.6 ± 18.5 vs. 93.6 ± 15.6, p < 0.05). The sputum eosinophil (in EA) and neutrophil (in NEA) counts increased with increasing asthma severity. CONCLUSION: Airway inflammation, especially eosinophilic inflammation, was associated with asthma severity and reduced pulmonary function in children.
    Acta Paediatrica 11/2012; · 1.97 Impact Factor
  • Otolaryngology Head and Neck Surgery 08/2012; · 1.73 Impact Factor
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    ABSTRACT: Purpose: The aim of the present study was to investigate the correlation between epileptiform discharges on EEGs after febrile seizures and the prognosis of patients in terms of the development of epilepsy and recurrence of febrile seizures. This study also evaluated the characteristics of epileptiform discharges and EEG changes on follow-up examination. Methods: This study consisted of 36 children who presented to our hospital with febrile seizures and whose electroencephalograms (EEG) showed epileptiform discharges. The development of epilepsy and the recurrence of febrile seizures were compared between the study group (n=36) and the control group (n=87), which included children with febrile seizure but with normal EEG findings. Results: No significant correlation was detected between the recurrence rate of febrile seizures in patients with normal EEG (23 out of 87, 26.4%) findings and that of patients whose EEGs showed epileptiform discharges (12 out of 36, 33.3%) [adjusted OR 0.67 (0.26-1.68)]. However, 9 (25.0%) out of 36 patients with epileptiform discharges on EEG had epilepsy compared to 2 patients (2.3%) in the control group. The correlation was statistically significant [crude OR 10.88 (2.47-47.88) and adjusted OR 8.75 (1.49-51.6)]. Conclusion: Epileptiform discharges on the EEGs of patients with febrile seizures are important predictive risk factors of the development of epilepsy.
    Brain & development 08/2012; · 1.74 Impact Factor
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    ABSTRACT: Exhaled nitric oxide (eNO) has been proposed as a noninvasive marker of airway inflammation in asthma. In asthmatic patients, exhaled NO levels have been shown to relate with other markers of eosinophilic recruitment, which are detected in blood, sputum, bronchoalveolar lavage fluid and bronchial biopsy samples. The purpose of this study was to assess the possible relationship between eNO and allergic inflammation or sensitization in childhood asthma and allergic rhinitis. Subjects consisted of 118 asthmatic children, 79 patients with allergic rhinitis, and 74 controls. Their age ranged from 6 to 15 yr old. eNO level, peripheral blood eosinophil count, eosinophil cationic protein (ECP), serum total IgE level and specific IgE levels were measured. Methacholine challenge test and allergic skin prick test for common allergens were performed in all subjects. Atopic group (n = 206, 44.48 ± 30.45 ppb) had higher eNO values than non-atopic group (n = 65, 20.54 ± 16.57 ppb, P < 0.001). eNO level was significantly higher in patients with asthma (42.84 ± 31.92 ppb) and in those with allergic rhinitis (43.59 ± 29.84 ppb) than in healthy controls (27.01 ± 21.34 ppb, P < 0.001) but there was no difference between asthma and allergic rhinitis group. eNO also had significant positive correlations with Dermatophagoides pteronyssinus IgE level (r = 0.348, P < 0.001), Dermatophagoides farinae IgE level (r = 0.376, P < 0.001), and the number of positive allergens in skin prick test (r = 0.329, P = 0.001). eNO had significant positive correlations with peripheral blood eosinophil count (r = 0.356, P < 0.001), serum total IgE level (r = 0.221, P < 0.001), and ECP (r = 0.436, P < 0.001). This study reveals that eNO level is associated with allergic inflammation and the degree of allergic sensitization.
    Journal of Korean medical science 10/2011; 26(10):1265-9. · 0.84 Impact Factor