• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.124-129
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• 2006

Purpose : We investigated the causative organisms of bacterial meningitis by age distribution from 1996 to 2005. Methods : Retrospective data were obtained from the medical records with diagnosis of bacterial meningitis or neonatal meningitis from 1996 through 2005. A case was defined by isolation of organism or detection of its antigen by latex agglutination from cerebrospinal fluid. Results : A total of 46 cases(27 neonates and 19 children) were identified. 15 of 27 episodes(55.6%) of neonatal meningitis had a concomitant-positive blood culture. Group B streptococci were the most common bacterial causes of neonatal meningitis(44.4%). Nine of 12 episodes(75.0%) were late-onset infections in neonatal meningitis caused by group B streptococci. 16 of 19 children(84.2%) with bacterial meningitis beyond the neonatal period were younger than 5 years of age(median age, 23 months). Of 19 cases, 8 infections were with Streptococcus pneumoniae, 8 were with Haemophilus influenzae and 3 were with Neisseria meningitidis. Since 2001 there was no case of meningococcal meningitis in this study. Conclusion : In neonates group B streptococci are the most common causative organisms of bacterial meningitis, especially late-onset infections. In infants and young children, the predominant causes of bacterial meningitis are H. influenzae and S. pneumoniae; meningitis caused by the former are likely to decrease after the introduction of the conjugate vaccine for H. influenzae type b.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.197-203
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• 1999

The albino plants of tobacco (Nicotiana tobacum L. cv. BY-4) were isolated from seed populations that were induced by heavy-ion ($^{14}N$) beam irradiation to proembryo and the in vitro growth and differentiation have been characterized. The in vitro cultured albino plants showed significant reduction of chlorophyll content and possessed larger number of stomata on both upper and lower epidermis than that of wild-type plants. Stem growth of the mutants remained dwarfed, however, the internode recovered its normal length after GA$_3$ treatment (10.0mg/L) on the MS medium containing sucrose under continuous light. When explants of leaf blades of albino plants were cultured, multiple shoots formed directly on MS medium containing 1.0mg/L of BAP or kinetin and a large number of calli were induced on the MS medium containing 1.0mg/L NAA or 1.0 mg/L 2,4-D. The albino calli regenerated multiple albino plantlets in the MS medium containing 0.1mg/L NAA + 1.0 mg/L BAP. No significant differences between the wild-type and albino plants were detected in the multiple shoot induction, callus formation from the explants and the plantlets regeneration from calli. In addition, albino plants have a similar organogenesis Pattern to that of the wild-type in the media with different combinations of NAA (0 to 5.0mg/L) and BAP (0 to 5.0mg/L) treatment. These results indicate that the albino mutant has the same normal regeneration ability as that of wild-type, although the mutant has lost functions in photosynthesis, such as pigmentation.

• Journal of Korean Society of Forest Science
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• v.74 no.1
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• pp.56-60
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• 1986

Excised mature embryos of P. koraiensis were plated on a series of G.D. basic media supplemented with growth regulators as follow; $0.1mg/{\ell}$ NAA(M-1); $0.1mg/{\ell}$ NAA and 2,4-D (M-2); $0.1mg/{\ell}$ 2,4-D and BAP (M-3); $0.1mg/{\ell}$ 2,4-D and kinetin (M-4). Cytological study of the callus showed that thercentage of occurrance of diploid cells was observed 52% in M-3 and 36% in M-4, while that was revealed 29% in M-1 and 17% in M-1. The frequency of diploid cells was increased on the M-3 and M-4 media. The stable chromosome state is a crucial factor for organogenesis. Therefore, it can be inferred that the callus tissues cultured on media supplemented with both auxin and cytokinin have the greatest possibility of organogenesis.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.385-393
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• 1997

다세포 생물에서 몸의 효율적 생존을 위한 각 기관의 homeostasis는 세포 증식과 사망에 의해 조절된다. 따라서, apoptosis라 명명된 세포사망은 정교한 기전에 의한 능동적이고 자발적인 사망기전으로써 몸의 정상적 유지를 위한 필수적인 현상이다. 발생기 세포나 신경세포 또는 흉선세포 분화 동안 과다한 세포의 제거가 apoptosis의 대표적인 예이며, 각종 호르몬에 의해 그 기능이 조절되는 난소세포에서도 apoptosis가 활발히 일어난다. Rat난소에는 태어날 때 수십 만개의 난포를 지니고 있는데, 이 중 단지 1%만이 배란에 사용되어질 뿐이고 나머지는 모두 사망하게 된다. 이러한 난포사망은 난소의 적절한 세포 수를 유지하기 위한 필수적 과정이며, 인위적으로 apoptosis를 억제하는 유전자인 bcl-2를 과다 발현시키면 난소암이 발생하는 연구결과가 이를 입증해주고 있다. 이처럼 중요한 난포 사망기전은 apoptosis라는 개념이 정립되면서 최근 들어 점차 그 연구가 활발해지고 있다. Apoptosis의 특징 중 뚜렷한 점은 DNA가 일정한 간격으로(180∼200 bp)잘려지는 DNA fragmentation현상으로, 이를 이용하여 DNA3'-end 부위에 방사선동위원소를 label한 후 이를 전기영동으로 분리하면 apoptosis를 손쉽게 측정할 수 있다. 난소의 기능은 시상하부호르몬인 LH와 FSH 뿐만 아니라 난소에서 분비되는 각종 난소국부호르몬들에 의해 조절된다. 특정한 발육단계의 난포는 특정한 호르몬에 의해 그 기능을 조절 받는데, 이러한 난소기능 조절기작은 매우 복잡한 경로를 지니고 있다. 이러한 복잡한 기작으로 인해 초기 연구에서첨 생체 내에서 밝히려는 연구 시도는 어려움에 부딪치게 되었다. 생체내 실험은 난소가 다양한 발육단계의 난포를 동시에 지니고 있어 특정한 발육단계의 난포 사망기전을 연구하기 어렵다. 또한 난포는 생체 내에서 다양한 호르몬을 동시에 분비하기 때문에 특정한 난소국부호르몬이 사망기전에 미치는 영향을 조사하기 힘든 점이 있다. 최근 들어 난포체외배양이 다양하게 개발되면서, 이러한 어려운 점을 극복할 수 있게 되었다. 본 논문은 각 발육단계의 난포를 절단해 체외배양하면서, apoptosis DNA 절단 현상을 이용하여 각종 난소국부 호르몬들이 난포발육단계별로 사망기전에 미치는 영향을 요약해 보였다. 난포는 발육하면서 점차 복잡한 호르몬 경로를 생존을 위해 필요로 한다. Prevulatory난포생존에 필요한 난소국부호르몬들은 early antral 단계의 난포에서는 그 미치는 영향이 감소되다가 preantral단계의 난포에서는 영향을 전혀 미치지 못했다. 단지 예외는 cGMP처리로써, 세포내 cGMP수준을 일정하게 유지시켜주는 것이 난포발육단계에 무관하게 생존에 중요한 인자로, 장래 연구는 난포 세포내의 cGMP수준을 조절하는 기작을 규명하는데 있을 것이다.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.359-362
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• 2003

The recent development of methods for culturing hair follicles in vitro has proved an important tool to investigate many aspects of drug screening. Human hair follicle is composed of multiple types of cells, whose interactions regulate morphology and cycling-anagen, catagen, and telogen. Many investigators have tried to develop models to prolong of the period of hair elongation in vitro. However these are limited in submerged culture, which don't work due to the lack of cell-cell interactions which are abundant in vivo environment. So we applied dermal equivalent (DE) to culturing flair follicles to prolong hair growth period.

• Journal of Plant Biotechnology
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• v.44 no.4
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• pp.454-461
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• 2017

This study was conducted to investigate the optimal conditions for spore germination, prothallus propagation, sporophyte formation, and seedling growth in Polystichum braunii (Spenn.) $F{\acute{e}}e$. The rate of spore germination and early prothalium development was high in Knop (41.2%), which had low mineral content. The optimal medium for prothallus propagation and sexual organ formation was 2MS medium (2% sucrose). Among the various mixtures of cultivation soil (bedding soil, peat moss, perlite, and decomposed granite), a mixture of bedding soil and decomposed granite at a ratio of 2:1 (v:v) had a positive effect on sporophyte formation (276.3 ea/$7.5m^2$). The most efficient conditions for promoting the growth of sporophytes were pots filled with only bedding soil.

• Korean Journal of Medicinal Crop Science
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• v.1 no.1
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• pp.43-48
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• 1993

Present experiments were carried out to examine the effect of plant growthregulators for callus induction and plantlet regeneration through leaf tissue culture of Scutellaria baicalensis GEORGI. The results indicated that Callus was induced well on MS medium supplemented with 0.5mg/L NAA or 0.5mg/L NAA Plus 0.5mg/L zeatin. MS medium supplemented with 1.0mg/L BAP plus 0. 5mg /L NAA or 1. 0mg /L zeatin Plus 0.5mg /L NAA and 1.0mg /L NAA were the most effective for plant regeneration. Thin layer chromatogram of baicalin component (Rf 0.39) was observed from callus cultured on MS medium containing 0.5mg /L NAA plus 0.5mg /L zeatin.

• Korean Journal of Medicinal Crop Science
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• v.1 no.1
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• pp.38-42
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• 1993

The present study was carried out to assess the possibility of rapid multiplication of Zingiber mioga ROSC. through in vitro culture of shoot-apex. The factor investigated was effect of various growth regulators on shoot-apex culture. The shoot-apex cultured of M. S. (Murashige and Skoog) medium developed into plantlet in 12 Weeks. M. S. medium containing NAA at 05ppm and BA 5.0ppm was found to be optimal for growth of in vitro plantlet.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.67-72
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• 2004

An efficient protocol has been developed for rapid mass propagation of sweetpotato from shoot-tips derived embryogenic callus. Optimal embryogenic callus was induced from shoot apical meristem explants on Murashige and Skoog (MS) medium supplemented with 1mg/L 2,4-D. The addition of casein hydrolysate in the media increased the embryogenesis efficiency of sweetpotato. Somatic embryos were easily induced from the embryogenic callus on MS basal medium containing 300-500mg/L casein hydrolysate without phytohormon. Treatment of casein hydrolysate (100∼300mg/L) with 1mg/L 2,4-D also improved the secondary embryonic efficiency from somatic embryos below 2mm in length. Plant regeneration was achieved via somatic embryogenesis and direct organogenesis. Regenerated planlets with well developed shoots and roots on MS basal medium were successfully transferred to soil.

• Applied Biological Chemistry
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• v.16 no.3
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• pp.118-127
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• 1973

Effects of nitrogen sources oi phosphorus sensitivity in soybeans were investigated using three nitrogen source ($NH_4-N,\;NO_3-N$ and urea) and six cultivars (Lee, Hill, R56-49, Harosoy, Clark-63 and Chippewa), differing in phosphorus sensitivity. Growth inhibition with ammonium or urea medium increased with phosphorus sensitivity indicating that the phosphorus sensitive cultivars are also sentitive to ammonium. The sensitive Clark-63 was inhibited two folds more than the tolerant Lee in ammonium medium. These results strongly suggest that phosphorus sensitivity is closely linked to nitrogen metabolism and ammonium toxicity. Nitrogen sources gave special morphorogical growth patterns (short internode-many branchs in $NO_3-N$, long internode-no branches in $NH_4-N$ and a low top to root ratio in urea) by affecting differently the growth of plant organs.