• Korean Journal of Microbiology
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• v.52 no.4
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• pp.428-436
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• 2016

The emergence of antibiotic-resistant bacteria has been increased and become a public health concern worldwide. Many bacterial infections can be sequentially treated with different types of antibiotics. Thus, this study was designed to evaluate the changes in survival, antibiotic susceptibility, mutant frequency, ${\beta}$-lactamase activity, biofilm formation, and gene expression in Klebsiella pneumoniae after exposure to sequential antibiotic treatments of ciprofloxacin and meropenem. Treatments include control (CON; no addition), 1/2 MIC ciprofloxacin addition (1/2CIP), 2 MIC ciprofloxacin addition (2CIP), initial 1/2 MIC ciprofloxacin addition followed by 1/2 MIC meropenem (8 h-incubation) and 2 MIC ciprofloxacin (16 h-incubation) (1/2CIP-1/2MER-2CIP), initial 1/2 MIC ciprofloxacin addition followed by 1/2 MIC meropenem (8 h-incubation) and 2 MIC meropenem (16 h-incubation) (1/2CIP-1/2MER-2MER), and initial 1/2 MIC ciprofloxacin addition followed by 2 MIC ciprofloxacin(8 h-incubation) and 2 MIC meropenem(16 h-incubation) (1/2CIP-2CIP-2MER). No growth of K. pneumoniae was observed for the 2CIP throughout the incubation period. The numbers of planktonic cells varied with the treatments (7~10 log CFU/ml), while those of biofilm cells were not significantly different among treatments after 24-h incubation, showing approximately 7 log CFU/ml. Among the sequential treatments, the least mutant frequency was observed at the 1/2CIP-1/2MER-2CIP (14%). Compared to the CON, 1/2CIP-2CIP-2MER decreased the sensitivity of K. pneumoniae to piperacillin, cefotaxime, and nalidixic acid. The highest ${\beta}$-lactamase activity was 22 nmol/min/ml for 1/2CIP-1/2MER-2CIP, while the least ${\beta}$-lactamase activity was 6 nmol/min/ml for 1/2CIP-2CIP-2MER. The relative expression levels of multidrug efflux pump-related genes (acrA, acrB, and ramA) were increased more than 2-fold in K. pneumoniae exposed to 1/2CIP-1/2MER-2MER and 1/2CIP-2CIP-2MER. The results suggest that the sequential antibiotic treatments could change the antibiotic resistance profiles in K. pneumoniae.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.406-413
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• 2012

Effect of three additives, chitosan, ferric chloride, and MPE50 on membrane fouling reduction was studied. They were introduced with various dosing rate into activated sludge, and changes in filtration resistance measured by the batch cell filtration test were evaluated. Both the filtration resistance and the specific cake resistance were minimized at 20 mg/g-MLSS with chitosan, 70 mg/g-MLSS with ferric chloride, and 20 mg/g-MLSS with MPE50 addition, respectively. Introduction of the additives into the activated sludge resulted in reduction of not only cake resistance, but also fouling resistance. However, the chitosan addition to three different activated sludge resulted in three different optimal dose of 10, 20, 30 mg/g-MLSS, respectively. This implies that the optimal dose is dependent on sludge characteristics rather than a constant value. Overdose above the optimal dosage always aggravated filterability in all cases. Zeta potential of sludge flocs, relative hydrophobicity, floc size distribution, soluble EPS concentration and supernatant turbidity were measured in order to analyze fouling reduction mechanism. Nearly neutral surface charge along with the largest particle size was observed at the optimal dose. This could be explained by particle destabilization and restabilization mechanism as positively charged additives were injected into sludge flocs of negative surface charge. Both soluble EPS concentration and supernatant turbidity also showed the lowest value at the optimal dose. These foulants are believed to be coagulated and entrapped in sludge flocs during flocculation. Chitosan and MPE50 which are cationic polymeric substances showed higher reduction in both soluble EPS and fine particles comparing with ferric chloride.

• Journal of the Korean Society of Food Culture
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• v.20 no.3
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• pp.305-314
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• 2005

This study was conducted to investigate the effects of ginseng and Schizandra chinensis on the quality characteristics of kimchi stored for 40 days at $4^{\circ}C$ after kimchi was fermented for 1 day at $25^{\circ}C$. pH and reducing sugar of GS(Kimchi added with extract powder of fine ginseng root and Schizandra chinensis juice) were the highest in the early part of storage but pH and reducing sugar of G(Kimchi added with extract powder of fine ginseng root) were the highest from 11th storage day. Acidity and $CO_2$ content of GS were the highest during storage period. The $CO_2$ content of GS was the highest significantly and the $CO_2$ content of C(Control) was the lowest significantly. When the hardness was measured, G was the hardest and there were no significant difference between C and GS. Total cells and lactic acid bacteria were increased rapidly at initial fermentation and GS was the highest of 3 samples from 6th storage day. The result of sensory evaluation showed that G was lower in sourness and higher in hardness than C and GS. Ginseng flavor had no significant differences between G and GS. And G was higher than GS in bitter taste. Consumer Acceptance test showed that consumer prefered C and GS to G. Considering all results, it can be concluded that addition of Schizandra chinensis juice to kimchi decreases the bitter taste of ginseng and increasing consumer preference.

• Food Science and Preservation
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• v.25 no.1
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• pp.145-154
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• 2018

The purpose of this study was to investigate the ability of natural antioxidants as stabilizers for meat by-products to prevent lipid oxidation. The white internal organs were evaluated using different treatments: no antioxidant (control), ascorbic acid (T1), Artemisiacapillaris Thunb. (T2), Opuntia (T3), Schisandra chinensis (T4), and Saururuschinensis (Lour.) Baill (T5). Antioxidant activities were analyzed by measuring DPPH contents, superoxide anion radical levels, nitrate scavenging activities, and total polyphenol contents. T1 and T2 showed higher antioxidant activities and total polyphenol contents (p<0.05). Additionally, changes in physicochemical properties (pH, color, volatile basic nitrogen [VBN], and thiobarbituric acid reactive substances [TBARS]) and microbiological aspects in white internal organs processed with antioxidants were investigated. As storage time increased, the CIE $a^*$ and $b^*$ values of the white internal organs processed with natural antioxidants were decreased (p<0.05), and CIE $L^*$ values were low, particularly for the T3 sample relative to that in the control. Moreover, the pH, VBN, and TBARS values of samples T2-T5 were increased after 7 days of storage, but showed low values compared with those of the control (p<0.05). Moreover, compared with the control group, the treatments showed antimicrobial effects. Our results indicated that these natural antioxidants could be used as lipid oxidation stabilizers of meat by-products during storage and that Artemisiacapillaris Thunb. and Opuntia may have applications as natural antioxidants in the meat by-product industry.

• Economic and Environmental Geology
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• v.36 no.1
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• pp.27-38
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• 2003

Arsenic contamination around Au-Ag mining areas occurs mainly from the oxidation of arsenopyrite which is frequently contained in mine tailings. In weathered tailings, oxidation of sulfide minerals typically results in the formation of abundant ferric (oxy)hydroxides or (oxy)hydroxysulfates near the tailings surface, and arsenic may be associated with these secondary precipitates. In this study, solid phases of arsenic in weathered tailings of some Au-Ag mines were investigated through the SEM/EDS and sequential extraction analyses. The stability of As solid phases and the leaching potential were assessed with the variation of pH and Eh conditions. Oxidation of sulfides in the tailings samples was indicated by depletion of S molar concentrations compared to As and heavy metals. Under XRD examinations, jarosite as an Fe-oxyhydroxysulfate was found in the tailings of Deokeum, Dongil and Dadeok, and scorodite as an As-bearing crystalline mineral was identified from Dadeok which has the highest concentration of As (4.36 wt.%). Beudantite-like phases and some Pb-arsenates were also found under SEM/EDS analysis, and most of As phases were associated with Fe-(oxy)hydroxides and (oxy)hydroxysulfates despite a few arsenopyrite from Samgwang and Gubong. Sequential extraction analysis also showed that As was present predominantly as coprecipitated with Fe hydroxides from Dongil, Dadeok and Myungbong (72∼99%), and as sulfides (58%) and Fe hydroxide-associated forms (40%) from Samgwang and Gubong. In the tailings leaching experiment, As was released with high amounts by the dissolution of As-bearing Fe(oxy)hydroxysulfates in the lowest pH (2.7) conditions of Deokeum, and by desorption under alkaline conditions of Samgwang and Gubong. Higher leaching rates of arsenite(+3) were found under acidic conditions, which pose a higher risk to water quality. Changes in pH and Eh conditions coupled with microbial processes could influence the stabilities of the As solid phases, and thus, time amendments or landfilling of weathered tailings may result in enhanced As mobilization.

• Pediatric Infection and Vaccine
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• v.5 no.1
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• pp.69-78
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• 1998

Purpose : The risk of severe tuberculous disease such as meningitis or miliary tuberculosis increases as younger is the child at the time of infection. Therefore, the early diagnosis and prompt treatment is mandatory for infants with tuberculosis. This study was undertaken to describe the epidemiology, clinical and radiographic manifestations, and response to therapy in infants with tuberculous disease. Methods : Medical records of 29 infants with tuberculosis diagnosed at the Seoul National University Children's Hospital from July, 1985, to April, 1997, were reviewed, retrospectively. A case of tuberculosis was confirmed if M. tuberculosis was isolated from any body site or if there was histologic proof of tuberculosis. Otherwise, the diagnoses were individualized considering history of contact with contagious adult case, clinical manifestations, chest X-ray findings, result of a Mantoux test reaction with 5 tuberculin unit of PPD, and the response to therapy. Results : The mean age at diagnosis was $7.00{\pm}2.65$ months (range, 3 to 12 months). Twelve cases had isolated pulmonary diseases, and the rest had pulmonary disease and meningitis, 5 cases; pulmonary disease and cervical lymphadenitis, 3; isolated meningitis, 3; and miliary tuberculosis, 6. Source case was identified in 19 cases, 7 of which were detected with retrograde manner. Twenty seven of 29 were symptomatic at their initial visit. The presenting symptoms were mainly respiratory or neurologic, and respiratory difficulty was accompanied in 7 cases. Physical examination revealed wheezing in 7 cases and decreased breath sounds in 9. Hepatomegaly or hepatosplenomegaly were frequent. Chest radiographs showed lung parenchymal disease with hilar lymphadenopathy in 18 cases, and focal or generalized emphysematous change in 7 cases. Conclusion : Most of the infants with tuberculosis are symptomatic at diagnosis, and many of infants with intrathoracic tuberculosis presented with symptoms of bronchial obstruction. When tuberculosis is suspected in an infant, the adult source case should be vigorously investigated to aid in diagnosis and for the prevention of further transmission of tuberculous disease. Almost half of infant tuberculosis are preventable if prophylaxis were given when adult cases were diagnosed.

• Korean Journal of Organic Agriculture
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• v.13 no.4
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• pp.389-400
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• 2005

This study was conducted to investigate into the ecological environments and the soil microflora of purple-bracted plantain lily (Hosta longipes Matsumura) for wild vgetables. Native soil textures of purple-bracted plantain lily were in the order of sandy loam (SL) > loam (L) > clay loam (CL). pH in soil was relatively acid by 4.8, electric conductivity was 0.08mS/cm, and organic matter content was 0.08g/kg. CEC was measured by $100.8cmol^{(+)}kg^{-1}$ and available phosphate was 103.4mg/kg. Contents of exchangeable cations in terms of potassium, calcium, and magnesium were measured by $0.33cmol^{(+)}kg^{-1},\;2.26cmol^{(+)}kg^{-1},\;and\;0.87cmol^{(+)}kg^{-1}$, etc. Diurnal changes in the air temperature of the natives were 15 to $20^{\circ}C$, that temperature differential was relatively little compared with that in open field by 15 to $30^{\circ}C$. Relative humidity in the natives were much more humid by 60 to 80% compared with that in open feld by 35 to 85%. Light intensity in the natives and the open field at ten o'clock were $2,300{\mu}mol/m^2/sec.\;and\;1,750{\mu}mol/m^2/sec.$ Total number of soil microorganisms were $8.4{\times}10^7\;c.f.u./g$. Mycorrhizal spore densities over $500{\mu}m,\;355{\sim}500{\mu}m,\;251{\sim}354{\mu}m,\;107{\sim}250{\mu}m\;and\;45{\sim}106{\mu}m$ were 0.8, 1.3, 2.1, 38.1, and 110.0 respectively. Mycorrhizal root infections by vesicle and hyphae were 17% and 6%. However, arbuscules in the roots were not shown.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.4
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• pp.362-371
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• 2016

The distribution patterns of Chromophoric Dissolved Organic Matter (CDOM) and the chemical characteristics of CDOM in the Seomjin river estuary were investigated in March, June and July 2012 in order to determine the spatial and temporal variability of CDOM along the salinity gradient considering the effects of mixing, nutrients and Chl a. The average CDOM values were $1.0{\pm}0.3m^{-1}$, $1.3{\pm}0.4m^{-1}$, and $1.4{\pm}0.3m^{-1}$ in March, June and July, respectively. A high concentration of CDOM (greater than $1.5m^{-1}$) was found at the head of the river which decreased towards the river mouth to as low as less than $0.5m^{-1}$. The average concentrations of CDOM increased from the dry season (March and June) to the wet season (July), and the average slope values ($S_{300-500}$), which were used as indicators of CDOM characteristics and sources, were in the range of $0.013-0.018m^{-1}$. The CDOM and $S_{300-50}$ values showed that not only the concentration of CDOM but also the chemical properties of DOM clearly changed between upstream and downstream in the Seomjin river. CDOM and FDOM showed a negative correlation with salinity ($R^2$ > 0.8), and CDOM was positively correlated with FDOM. Furthermore, the mixing pattern of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM were salinity (mixing) and water temperature, which meant the dilution of low CDOM seawater, was the controlling factor for the spatial distribution of CDOM. Increases in water temperature seemed to induce the production of CDOM during summer (June and July) through the biological degradation of DOM either by microbial activity or photo-degradation.

• Clinical and Experimental Pediatrics
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• v.52 no.1
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• pp.61-67
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• 2009

Purpose : The rate of drug-resistant tuberculosis (DR-TB) in children is an indicator of the effectiveness of TB control programs in the community. This study aimed to assess the prevalence of DR-TB in children and evaluate TB management. Methods : Between January 1999 and July 2007, drug susceptibility tests for anti-TB drugs were employed for patients aged less than 19 years with culture-positive TB. Results : A total of 607 cases (16.6%) were resistant to at least one anti-TB drug as follows: isoniazid (INH; 13.8%), rifampin (8.9%), pyrazinamide (4.2%), streptomycin (3.7%), ethambutol (EMB; 5.9%), and para-aminosalicylic acid (PAS; 1.9%). Multidrug-resistant (MDR) TB was found in 276 cases (7.6%); extensive drug resistant (XDR) TB, in 5 cases (0.2%). The rate of resistance to at least one anti-TB drug in children aged >15 years (16.1%) was significantly lower than that in children aged <15 years (20.5%) (P=0.016). The rate of resistance to at least one anti-TB drug and multidrug-resistance in this survey decreased significantly (P<0.001) as compared to the previous survey (1987-1995). The rate of resistance to INH, EMB, and PAS also significantly decreased (P<0.05). Conclusion : The rate of DR-TB in children in Korea has decreased over time; however, it remains higher than that in other countries. MDR-TB and XDR-TB are the emerging problems in Korean children. Therefore, the selection of effective drugs through drug susceptibility tests and evaluating risk factors of resistant TB is essential to successful therapy and a decreased incidence of DR-TB.