• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.146-151
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• 2008

Purpose : Multidrug-resistant Acinetobacter baumannii (A. baumannii) is recognized to be the most difficult pathogen to control and treat in pediatric burn centers. We analyzed the antibiotic susceptibility pattern of A. baumannii in our pediatric burn intensive care unit during the past 7 years. Methods : We retrospectively evaluated 56 patients (105 samples) under the age 15 years and who were infected with A. baumannii between January 1999 and December 2005. Results : Fot the 56 patients, the ratio of males to females was 1.15:1 and the median age was 48.3 months. The sites of 105 isolates were wounds (65%), sputum (20%), blood (6 %), cutdown tips (5%), endo-tip tubes (2%) and urine (2%). A. baumannii presented yearround. The annual antimicrobial resistance rate increased and the multidrug resistant rate for two or more antibiotics was 93.33%. For 3 patients in whom resistance emerged, the interval period between the susceptible and resistant strains after antibiotic use was a mean of 10 days. The A. baumannii isolated from blood were all multi-drug resistant pathogens. Conclusion : Multidrug resistance of A. baumannii is increasing. Strict infection control guidelines and active surveillance are needed for the prevention and treatment of A. baumannii in hospitals.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.320-324
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• 2017

Development of modern agricultural machinery and accompanying agricultural development cause soil compaction and reduce growth by stressing roots. Kalanchoe pinnata was used to investigate the impact of stress on rooting and changes in plant growth and reproduction. K. pinnata forms somatic embryos capable of asexual reproduction at the edge of leaves. Impact of root pressurization of K. pinnata on somatic embryogenesis and organ differentiation according to external stress factors was investigated by using a high concentration of agar and this phenomenon was studied histologically. Agar concentration in culture media ranged from 0.5%-1.5% to induce a compression effect on roots. The stem and leaf of K. pinnata were subjected to a microtechnique process to study changes in tissue. In vivo, K. pinnata produced 2nd and 3rd plantlets at edges of leaves from lack of water and excessive lighting conditions. In in vitro culture studies, the lower the concentration of agar, the higher the population and the higher the biomass, but plantlet did not occur in leaf bends. Conversely, as concentration of agar increased, increase in the number of individuals was low. Plantlet development occurred only in agar 1.5% medium. The difference in agar concentration was a stressor in the root of K. pinnata, and thus the pattern of asexual reproduction changed from the division method in root to a plantlet generation in leaf. This suggests root pressurization may act as stress and change in the plant reproduction pattern.

• The Korean Journal of Mycology
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• v.15 no.3
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• pp.149-157
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• 1987

This study was undertaken to investigate the differentiation, from spore germination to hyphae growth and phialide formation, of Aspergillus niger through the method of synchronous and submerged culture. Through continuous experiments by shake culture with potassium acetate medium, we observed the formation of spores at appropriate concentration and pH. Potassium acetate medium was set pH 5.5, 6.0, 6.5 and 7.0 on each scale, and control, 20 mM, and 40 mM, 80 mM and 160 mM concentrations on the other scale. Aspergillus niger was cultured in the defined media at $28^{\circ}C$, and mycelial dry weight, changes of pH and the onset of sporulation were checked. The mycelial dry weight, increased in potassium acetate medium, and pH increased during mycelial growth and gradually decreased after the spore formation. When pH increased excessively in Potassium acetate medium with pH 7.0, the mycelia could not adapt and mycelial dry weight decreased gradually. At pH 5.5, the onset of sporulation was done within one day at 20 mM it took, at 80 mM three days and at 160 mM concentration. in two days, at 40 mM one to four days were taken, 80 mM concentration respectively. At pH 6.5, the onset of sporulation was done in three days and four days at 80 mM concentrations respectively. Spore formation was not shown at pH 7.0. In controlled medium with all levels of pH, spore formation was not shown.

• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.179-185
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• 2003

To determine whether the diphtheria toxin-A (DT) gene disrupts development of thymocytes in transgenic animal, the DT-A gene was used for the production of transgenic mice directed by proximal Ick promoter sequences. Two transgenic founder mice that contained several copies of transgene were produced by DNA microinjection and integration of transgene in transgenic mice was confirmed by PCR and Southern blotting analysis. Transgenic $F_1$ and $F_2$ mice were produced by outbreeding of founder and $F_1$ mice to investigate expression of transgene and phenotypes in transgneic mice. Expression of the diphtheria toxin gene was confirmed in thymus, spleen and liver of transgenic mice by RT-PCR. In circulating blood of transgenic mice, lower number of circulating white blood cells and platelets were observed compared with that of normal mice. In addition, transgneic mice had reduced number of circulating peripheral T-cells analyzed by FACS with anti-CD3 antibody. The data in these transgenic mice indicate that DT gene can play a disruptive role in developing thymocytes of transgenic mice resulted in lower number of T-cells that can be applicable to a wide range of tissues in other animals.

• Korean Journal of Plant Resources
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• v.29 no.1
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• pp.143-153
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• 2016

Plant regeneration via organogenesis and somatic embryogenesis was investigated in Korean soybean cultivars including Cheongja 3, Jinpumkong 2, Taekwangkong and Uram. Cotyledon, cotyledon+hypocotyl and hypocotyl segments of 7-day-old seedlings were cultured on MS medium containing various concentration (0, 1, 2 and 4 ㎎/L) of BA and TDZ. The results showed that MS medium supplemented with BA 2.0 ㎎/L yielded the highest shoot formation ratio of 83.3%. In 4 cultivars, Taekwangkong showed the highest ratio of shoot formation. When various sizes of immature cotyledons (S: 1∼ 2 ㎜, M: 3∼5 ㎜, L: 6∼8 ㎜) were tested on MS medium containing 2,4-D 40 ㎎/L for somatic embryogenesis, the optimum size for embryogenic callus induction was 3∼5 ㎜ in length of immature cotyledons. In 4 cultivars, Taekwangkong showed the highest percentage of embryogenic callus induction. The results indicate that Taekwangkong is the best soybean cultivar for plant regeneration via organogenesis and embryogenic callus induction among the 4 cultivars.

• Research in Plant Disease
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• v.9 no.1
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• pp.32-35
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• 2003

Pink rot of potato (Solanum tuberosum L.) occurred at Pyeongchang in Gangwon and at Bosung in Junnam province since 1999. The disease incidence in the surveyed areas was about 5% of harvested potatoes in 2002. Affected tubers showed a dull brown appearance and the lenticels and eyes on tubers turned dark brown. The cut surface of the diseased tuber colored faint pink and the entire surface of the diseased tuber becomes deep salmon pink within 30 min. The pathogen isolated from the diseased tubers was identified as Phytophthora erythroseptica based on morphological and cultural characteristics. Mycelial mat was fairly fluffy, rosette or stellate patterns and rounded or angular hyphal swellings were farmed in water, Temperature for mycelial growth was ranged from 5 to 3$0^{\circ}C$ and optimal temperature was $25^{\circ}C$. Non-papillate sporangia were persistent on stalk and ellipsoid, ovoid, obpyriform or distorted in shape, often with a constriction distal in the middle. Size of sporangia was 41.3~69.6$\times$26.8~47.4 (av, 55.5$\times$37.1) ${\mu}{\textrm}{m}$. Sexuality of Phytophthora erythroseptica was homothallic. Oogonia were 30~46 ${\mu}{\textrm}{m}$ in diameter and oospores were 28~35 ${\mu}{\textrm}{m}$ in diameter, Elongated or cyclindrical antheridia were all amphigynous. This is the first report on potato pink rot caused by Phytophthora erythroseptica in Korea.

• Pediatric Infection and Vaccine
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• v.18 no.2
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• pp.201-206
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• 2011

Purpose : Bacteremia is one of the most common causes of morbidity and mortality in children with cancer. The aim of this study was to evaluate the clinical features of bacteremia in pediatric cancer patients. Methods : We retrospectively analyzed bacteremia episodes occurred in pediatric cancer patients at Samsung Medical Center from January 2008 to December 2010. We excluded bacteremia episodes after hematopoietic stem cell transplantation. Results : A total of 141 blood cultures were positive in 121 patients. Thirteen cultures due to contamination were excluded. For analysis, 128 bacteremia episodes in 108 children were included. Gram-positive organisms accounted for 46.9% (60/ 128) and gram-negative organisms for 53.1% (68/128). The source of bacteremia was identified in 21.1% of episodes. Bacteremia due to catheter related infection was observed in 9.4% of episodes (12/128 episodes) and gram-positive organisms were isolated in 75% of episodes (9/12). There were 10 cases (7.8%) of bacteremia associated with septic shock and gramnegative organisms were isolated in 80% of episodes (8/10). Relapses were documented within 30 days in 2 patients who cleared bacteremia which was confirmed after negative blood cultures. Mortality associated with bacteremia was not observed. Conclusion : Continuous monitoring is needed to maintain the tailored strategies to manage pediatric cancer patients with neutropenic fever who are at high risk of developing bacteremia in each institution.

• Journal of Life Science
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• v.26 no.7
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• pp.789-795
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• 2016

A lymph node (LN) is one of the secondary lymphoid organs. An LN consists of a complicated 3 dimensional frame structure and several stromal cells. Fibroblastic reticular cells (FRC) are distributed in the T zone for interaction with T cells. FRC secrete homing chemokines such as CCL19 and CCL21. Moreover, FRC play a pivotal role in the production of extracellular matrix (ECM) into LN for ECM reorganization against pathogen infections. However, not much is known about the involvement of the immune reaction of FRC. The present report is for the characterization of FRC on immune response. For this, FRC were positioned in several infected situations such as co-culture with macrophage, lipopolysaccharide (LPS), and TNFα stimulation. When a co-culture between FRC and macrophage was performed, a morphological change in FRC was observed, and empty space between FRCs was created by this change. The soluble ICAM-1 protein level was up-regulated by co-culturing with Raw264.7 and the treatment of the ROCK inhibitor Y27632. The activity of matrix metalloproteinase (MMP) was up-regulated by LPS onto FRC. Furthermore, the inflammatory cytokine TNFα regulated the expression of ECM in FRC by a gene chip assay. Collectively, it suggests that FRC are involved in immune reactions.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.2
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• pp.260-264
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• 2019

An 84-year-old woman presented to the emergency department with a chief complaint of pressure sores of the anus. She had a urine catheter when she showed pyuria three times but had no fever. A microscopic examination revealed many grapevine-like Gram positive strains and neutrophils. After 24 hours of urine culture on blood agar, non-hemolytic mucous colonies were found and further enlarged after 48 hours of culture. The capsules were identified after India ink stain. The catalase was positive, but the tube coagulase and latex coagulase were both negative. The S. aureus was identified by Vitek-2 and mass spectrometer Vitek MS V-3 IVD. The strain was confirmed by 16S rRNA gene sequencing and multilocus sequence typing (MLST). The phenotypically atypical MRSA found in the tube coagulase and latex coagulase were both negative. MRSA often show no beta hemolysis as in this case but are rarely latex coagulase-negative. We report a woman whose urine culture showed non-hemolytic, tube coagulase-negative, and latex coagulase-negative MRSA.

• Pediatric Infection and Vaccine
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• v.30 no.1
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• pp.33-38
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• 2023

A case of persistent Ralstonia mannitolilytica bacteremia in the neonatal intensive care unit prompted source investigation due to its rarity. After an extensive investigation, a contaminated ultrasonic nebulizer was identified as the source, and the infection was controlled by removing the source. This study emphasizes the importance of further investigations, even in single cases of rare pathogens.