• IMMUNE NETWORK
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• v.12 no.5
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• pp.165-175
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• 2012

Vaccination is one of the most effective methods available to prevent infectious diseases. Mucosa, which are exposed to heavy loads of commensal and pathogenic microorganisms, are one of the first areas where infections are established, and therefore have frontline status in immunity, making mucosa ideal sites for vaccine application. Moreover, vaccination through the mucosal immune system could induce effective systemic immune responses together with mucosal immunity in contrast to parenteral vaccination, which is a poor inducer of effective immunity at mucosal surfaces. Among mucosal vaccines, oral mucosal vaccines have the advantages of ease and low cost of vaccine administration. The oral mucosal immune system, however, is generally recognized as poorly immunogenic due to the frequent induction of tolerance against orally-introduced antigens. Consequently, a prerequisite for successful mucosal vaccination is that the orally introduced antigen should be transported across the mucosal surface into the mucosa-associated lymphoid tissue (MALT). In particular, M cells are responsible for antigen up-take into MALT, and the rapid and effective transcytotic activity of M cells makes them an attractive target for mucosal vaccine delivery, although simple transport of the antigen into M cells does not guarantee the induction of specific immune responses. Consequently, development of mucosal vaccine adjuvants based on an understanding of the biology of M cells has attracted much research interest. Here, we review the characteristics of the oral mucosal immune system and delineate strategies to design effective oral mucosal vaccines with an emphasis on mucosal vaccine adjuvants.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1232-1238
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• 2004

To investigate the production and characteristics of thermostable levan sucrase from Rahnella aquatilis ATCC 33071, the levan sucrase gene from R. aquatilis was cloned and expressed in Escherichia coli without induction system. Expression of levansucrase gene in E. coli had no notable or detrimental effect on the growth of host strain, and the recombinant levan sucrase exhibited levan synthesis activity. Levansucrase was secreted to the periplasm in E. coli, and addition of $0.5\%$ glycine yielded further secretion of levansucrase to the growth medium and resulted in an increase of total levansucrase activity. Furthermore, the cellular levansucrase was evaluated for the production of levan by using toluene­permeabilized whole-cells. The levansucrase was thermostable at $37^{\circ}C$. The molecular size oflevan was $1{\times}\;10^{6}$ Da, as determined by HPLC, and the degree of polymerization of levan varied with incubation temperatures: Low incubation temperature was preferable for the production of high-molecular size levan. The present study demonstrated that the mass production of levan and levan oligosaccharides can be achieved by glycine supplementation to the growth medium or by toluene­permeabilized whole-cells.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.606-612
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• 1998

A microbial flocculant-producing gram-positive bacterium, strain TE11, was isolated from soil samples, and was identified as Bacillus subtilis by using the Midi system, the Biolog system, 16S rDNA sequence analysis, and some physiological and morphological characteristics. The maximum flocculant capsular biopolymer of TE11 strain (BCP, 4.9mg/ml) was obtained when it was grown in GA broth medium containing 3% glutamic acid, 2% glycerol, 0.5% citric acid, 0.5% $NH_4$Cl, 0.05% $MgSO_4.7H_2O,\; 0.05%\;K_2HPO_4\;,\; and\; 0.004%\; FeC1_3. 6H_2O,\; pH 7.2,\; at\; 30^{\circ}C$ for 70 h with shaking. When glycerol was used as an additional carbon source in the GA medium, TE11 produced only flocculant BCP without any by-product. The flocculant (BCP) was found to aggregate suspended kaolin and activated charcoal powder without cations, and its flocculating activity was significantly enhanced by the addition of bivalent cations such as $Ca^{2＋}.Zn^{2},\; and\; Mn^{2＋}$. The flocculation activity by addition of $Ca^{2+}$ was high in an acidic pH 4.0. In the case of $Zn^{2＋}$, high flocculating activity remained without significant loss in the broad range of pH 4.0 to 9.0.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1643-1649
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• 2016

The aims of this study were to characterize the molecular epidemiological profiles of CTX-M-producing uropathogenic Escherichia coli isolates from a tertiary hospital in Daejeon, Korea, and to investigate the genetic diversity and compare the prevalence of sequence types (STs) in different areas. Extended spectrum β-lactamase-producing E. coli strains isolated from urine were analyzed for CTX-M, integrons, and insertion sequence common regions (ISCRs) by PCR and sequencing. Multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), phylogenetic analysis, and rep-PCR were also used for molecular typing of the isolates. Of 80 CTX-M producers, 31 and 46 expressed CTX-M-15 and CTX-M-14, respectively. MLST analysis indicated that the most prevalent ST was ST131 (n = 34, 42.5%), followed by ST38 (n = 22, 27.5%), ST405 (n = 8, 10.0%), and ST69 (n = 6, 7.5%). Most CTX-M producers harbored class 1 integrons. ST131 strains belonged to phylogenetic group B2 and showed identical rep-PCR patterns, whereas ST69, ST38, and ST405 strains belonged to phylogenetic group D; the ST38 and ST405 strains displayed the same rep-PCR pattern, respectively. ST131 and ST38 isolates showed 21 and 19 distinct types, respectively, by PFGE. In Daejeon, D-ST38 CTX-M-14 producers were relatively more prevalent than in other countries and Korean cities. Our results indicate that CTX-M-producing E. coli isolates belonged mostly to ST131 or ST38 and were more related to hospital-onset than to community-onset infections and that the bla_CTX-M gene may vary according to the ST.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.854-866
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• 2016

The production cost of biodiesel from microalgae is still not competitive, compared with that of petroleum fuels. The genetic improvement of microalgal strains to increase triacylglycerol (TAG) accumulation is one way to reduce production costs. One of the most promising approaches is the isolation of starch-deficient mutants, which have been reported to successfully increase TAG yields. To date, such a stable mutant is not available in an oleaginous marine microalga, despite several advantages of using marine species for biodiesel production. Algae in the genus Dunaliella are known to tolerate high salt concentration and other environmental stresses. In addition, the cultivation processes for large-scale outdoor commercialization have been well established for this genus. In this study, Dunaliella tertiolecta was used to screen for starch-deficient mutants, using an iodine vapor-staining method. Four out of 20,016 UV-mutagenized strains showed a substantial reduction of starch content. A significantly higher TAG content, up to 3-fold of the wild-type level, was observed in three of the mutants upon induction by nitrogen depletion. The carotenoid production and growth characteristics of these mutants, under both normal and oxidative stress conditions, were not compromised, suggesting that these processes are not necessarily affected by starch deficiency. The results from this work open up new possibilities for exploring Dunaliella for biodiesel production.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1096-1104
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• 2014

$\small{L}$-Asparaginase from gram-positive bacteria has been poorly explored. We conducted recombinant overexpression and purification of $\small{L}$-asparaginase from Staphylococcus sp. OJ82 (SoAsn) isolated from Korean fermented seafood to evaluate its biotechnological potential as an antileukemic agent. SoAsn was expressed in Escherichia coli BL21 (DE3) with an estimated molecular mass of 37.5 kDa, determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Consistent with asparaginases in gram-negative bacteria, size-exclusion chromatography determined SoAsn as a homodimer. Interestingly, the optimal temperature of SoAsn was $37^{\circ}C$ and over 90% of activity was retained between $37^{\circ}C$ and $50^{\circ}C$, and its thermal stability range was narrower than that of commercial E. coli $\small{L}$-asparaginase (EcAsn). Both SoAsn and EcAsn were active between pH 9 and 10, although their overall pH-dependent enzyme activities were slightly different. The $K_m$ value of SoAsn was 2.2 mM, which is higher than that of EcAsn. Among eight metals tested for enzyme activity, cobalt and magnesium greatly enhanced the SoAsn and EcAsn activity, respectively. Interestingly, SoAsn retained more than 60% of its activity under 2 M NaCl condition, but the activity of EcAsn was reduced to 48%. Overall, the biochemical characteristics of SoAsn were similar to those of EcAsn, but its kinetics, cofactor requirements, and NaCl tolerance differed from those of EcAsn.

• Radiation Oncology Journal
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• v.37 no.2
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• pp.117-126
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• 2019

Purpose: The purpose of this study was to characterize and evaluate the clinical significance of volume changes of soft tissue sarcomas during radiation therapy (RT), prior to definitive surgical resection. Materials and Methods: Patients with extremity or pelvis soft tissue sarcomas treated at our institution from 2013 to 2016 with RT prior to resection were identified retrospectively. Tumor volumes were measured using cone-beam computed tomography obtained daily during RT. Linear regression evaluated the linearity of volume changes. Kruskal-Wallis tests, Mann-Whitney U tests, and linear regression evaluated predictors of volume change. Logistic and Cox regression evaluated volume change as a predictor of resection margin status, histologic treatment response, and tumor recurrence. Results: Thirty-three patients were evaluated. Twenty-nine tumors were high grade. Prior to RT, median tumor volume was 189 mL (range, 7.2 to 4,885 mL). Sixteen tumors demonstrated significant linear volume changes during RT. Of these, 5 tumors increased and 11 decreased in volume. Myxoid liposarcoma (n = 5, 15%) predicted decreasing tumor volume (p = 0.0002). Sequential chemoradiation (n = 4, 12%) predicted increasing tumor volume (p = 0.008) and corresponded to longer times from diagnosis to RT (p = 0.01). Resection margins were positive in three cases. Five patients experienced local recurrence, and 7 experienced distant recurrence, at median 8.9 and 6.9 months post-resection, respectively. Volume changes did not predict resection margin status, local recurrence, or distant recurrence. Conclusion: Volume changes of pelvis and extremity soft tissue sarcomas followed linear trends during RT. Volume changes reflected histologic subtype and treatment characteristics but did not predict margin status or recurrence after resection.

• BMB Reports
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• v.39 no.5
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• pp.560-570
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• 2006

Mistletoe (Viscum album) lectins, which are classified as a type II ribosome-inactivating protein (RIP) due to their unique biological function and the potential medical and therapeutic application in cancer cells, receive a rising attention. The heterodimeric glycoproteins contain the A-chain with catalytic activity and the B-chain with sugar binding properties. In recent years, studies involving the lectins from the white berry European mistletoe (Viscum album) and the yellow berry Korean mistletoe (Viscum album coloratum) have been described. However, the detailed mechanism in exerting unique cytotoxic effect on cancer cells still remains unclear. Here, we aim to understand and define the molecular basis and biological effects of the type II RIPs, through the studies of the recombinant Korean mistletoe lectin. To this end, we expressed, purified the recombinant Korean mistletoe lectin (rKML), and investigated its molecular characteristics in vitro, its cytotoxicity and ability to induce apoptotic cell death in cancer cells. To gain structural basis for its catalytic activity and sugar binding properties, we performed homology modeling studies based on the high degree of sequence identity and conserved secondary structure prediction between Korean and European, Himalayan mistletoe lectins, and Ricin.

• Journal of Plant Biotechnology
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• v.36 no.2
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• pp.115-123
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• 2009

In recent years, several genetically modified (GM) crops have been developed worldwide through the recombinant DNA technology and commercialized by various agricultural biotechnological companies. Commercialization of GM crops will be required the assesment of risks associated with the release of GM crops. In advance of the commercial release of GM crops, developer should submit the several information on GM crops for approval. In this study, we carried out to provide the molecular data for the risk assessment of GM rice containing insect-resistant gene, modified Cry1Ac (CryIAc1). Through the molecular analysis with CryIAc1 induced GM rice, we confirmed the steady integration and expression of transgene, the transgene copy number, the adjacent region sequences of inserted gene into rice genome, and the transgene stability in progenies. For the qualitative PCR detection methods, specific primer pairs were designed on the basis of integration sequences, and construct- and event-specific detection markers were developed for leaf folder-resistant rice, Cr7-1 line. From these results, we demonstrated that the molecular data and the PCR detection methods of leaf folderresistant GM rice could be acceptable to conduct the biosafety and environment risk assessment.

• The Korean Journal of Nuclear Medicine
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• v.38 no.2
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• pp.161-170
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• 2004

Molecular Nuclear Neuro-Imaging in "CNS" drug discovery and development tan be divided into four categories that are clearly inter-related.(1) Neuroreceptor mapping to examine the involvement of specific neurotransmitter system in CNS diseases, drug occupancy characteristics and perhaps examine mechanisms of action;(2) Structural and spectroscopic imaging to examine morphological changes and their consequences;(3) Metabolic mapping to provide evidence of central activity and "CNS fingerprinting" the neuroanatomy of drug effects;(4) Functional mapping to examing disease-drug interactions. In addition, targeted delivery of therapeutic agents could be achieved by modifying stem cells to release specific drugs at the site of transplantation('stem cell pharmacology'). Future exploitation of stem cell biology, including enhanced release of therapeutic factors through genetic stem cell engineering, might thus constitute promising pharmaceutical approaches to treating diseases of the nervous system. With continued improvements in instrumentation, identification of better imaging probes by innovative chemistry, molecular nuclear neuro-imaging promise to play increasingly important roles in disease diagnosis and therapy.