• Applied Microscopy
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• v.35 no.1
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• pp.15-22
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• 2005

Metallothionein (MT) is a low molecular weight, cysteine-rich, metal-binding, and non-enzymatic protein. The present study was carried out to investigate the expression of MT gene as well as the localization of MT in regenerating rat liver. In partial hepatectomized rats, MT mRNA was detected as early as 1 hr and reached a maximal level by 8 hr after the operation. Thereafter, this level decreased gradually until 24 hr, and it became similar to that of sham control. Meanwhile, time course of MT immunoreactivity using immunogold-labelling revealed that the number of gold particles in hepatocytes increased significantly by 12 hr, but decreased at 48 hr after partial hepatectomy. Ultrastructurally, immunogold particles indicating the presence of MT were distributed in both the cytoplasm and the nucleus of the rat hepatocytes, particularly the particles were distributed at rough endoplasmic reticulum and nucleolus and did not seem to adhere to mitochondria or lysosomes in proliferating hepatocytes. Briefly, high level of MT mRNA expression and the intense immunoreactivity and/or the specific localization of MT was observed during liver regeneration. These results suggest that MT possibly involves hepatocyte proliferation via the storage or the supply of various metal ions in the regenerating rat liver.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.3
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• pp.211-216
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• 2016

Micronucleus test is genotoxicity assay for detection of micronuclei in the cytoplasm of interphase cells. The reduction and replacement of in vivo toxicity testing on animals require the development of in vitro models to predict the genotoxicity or other tests for cosmetic products. In this study, we evaluated a genotoxicity assay for topically applied chemicals using a three-dimensional human reconstructed skin model, KeraSkin$^{TM}$. Two genotoxins, mitomycin C (MMC) and methyl methanesulfonate (MMS), induced significant dose-related increases in cytotoxicity and micronuclei induction in the skin model. In contrast, two non-genotoxins, 4-nitrophenol (4-NP) and trichloroethylene (TCE), induced cytotoxicity but not micronucleus formation. In conclusion, micronucleus test using human skin model may be useful for predicting in vitro genotoxic potentials of cosmetic products.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.89-93
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• 2008

Ferrimagnetic Copper-Iron-Chromium Oxide $CuFe_{0.9}Cr_{1.1}O_4$ has been investigated over a temperature range from liquid nitrogen temperature upto $N{\acute{e}}el$ temperature using the Mossbauer technique. Its $N{\acute{e}}el$ temperature is found to be 355 K. Above the $N{\acute{e}}el$ temperature the quadrupole splitting is found to be 0.50 mm/s. On the other hand, all the electric quadrupole shift values are zero below the $N{\acute{e}}el$ temperature within experimental error. These seemingly contradictory phenomena have been explained by the model that the magnetic hyperfine field is randomly oriented with respect to the principal axes of the electric-field-gradient tensor.

• Journal of Life Science
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• v.26 no.3
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• pp.376-386
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• 2016

Apoptosis induction has been proposed as an efficient mechanism by which malignant tumor cells can be removed following chemotherapy. The intrinsic mitochondria-dependent apoptotic pathway is frequently implicated in chemotherapy-induced tumor cell apoptosis. Since DNA-damaging agent (DDA)-induced apoptosis is mainly regulated by the tumor suppressor protein p53, and since more than half of clinical cancers possess inactive p53 mutants, microtubule-damaging agents (MDAs), of which apoptotic effect is mainly exerted via p53-independent routes, can be promising choice for cancer chemotherapy. Recently, we found that the apoptotic signaling pathway induced by MDAs (nocodazole, 17α-estradiol, or 2-methoxyestradiol) commonly proceeded through mitotic spindle defect-mediated prometaphase arrest, prolonged Cdk1 activation, and subsequent phosphorylation of Bcl-2, Mcl-1, and Bim in human acute leukemia Jurkat T cells. These microtubule damage-mediated alterations could render the cellular context susceptible to the onset of mitochondria-dependent apoptosis by triggering Bak activation, Δψm loss, and resultant caspase cascade activation. In contrast, when the MDA-induced Bak activation was inhibited by overexpression of anti-apoptotic Bcl-2 family proteins (Bcl-2 or Bcl-xL), the cells in prometaphase arrest failed to induce apoptosis, and instead underwent mitotic slippage and endoreduplication cycle, leading to formation of populations with 8N and 16N DNA content. These data indicate that cellular apoptogenic mechanism is critical for preventing polyploid formation following MDA treatment. Since the formation of polyploid cells, which are genetically unstable, may cause acquisition of therapy resistance and disease relapse, there is a growing interest in developing new combination chemotherapies to prevent polyploidization in tumors after MDA treatment.

• Journal of Life Science
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• v.27 no.1
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• pp.100-121
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• 2017

The sexual reproduction of the unicellular green alga Chlamydomonas is reviewed for a comprehensive understanding of the complex processes. The sexual life cycle of C. reinhardtii is distinguished into five main stages: gametogenesis, gamete activation, cell fusion, zygote maturation, and meiosis and germination. Gametogenesis is induced by nitrogen starvation in the environment. C. reinhardtii has two mating types: mating type plus ($mt^+$) and mating type minus ($mt^-$), controlled by a single complex mating type locus ($MT^+$ or $MT^-$) on linkage group VI. In the early gametogenesis agglutinins are synthesized. The $mt^+$ and $mt^-$ agglutinins are encoded by the autosomal genes SAG1 (Sexual AGglutination1) and SAD1 (Sexual ADhesion1), respectively. The agglutinins are responsible for the flagellar adhesion of the two mating type of gametes. The flagellar adhesion initiates a cAMP mediated signal transduction pathways and activates the flagellar tips. In response to the cAMP signal, mating structures between two flagella are activated. The $mt^+$ and $mt^-$ gamete-specific fusion proteins, Fus1 and Hap2/Gcs1, are present on the plasma membrane of the two mating structures. Contact of the two mating structures leads to develop a fertilization tubule forming a cytoplasmic bridge between the two gametes. Upon fusion of nuclei and chloroplasts of $mt^+$ and $mt^-$ cells, the zygotes become zygospores. It is notable that the young zygote shows uniparental inheritance of chloroplast DNA from the $mt^+$ parent and mitochondrial DNA from the $mt^-$ parent. Under the favorable conditions, the zygospores divide meiotically and germinate and then new haploid progenies, vegetative cells, are released.

• The Korean Journal of Nuclear Medicine
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• v.32 no.1
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• pp.89-98
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• 1998

The search for tumor-avid agents for use in nuclear medicine imaging is an ongoing field of importance. The purpose of this study was to determine the affinity for radio labeled vitamin $B_{12}$ by a wide histologic variety of tumor types in mice. Seventeen different types of tumor were grown subcutaneously in female Balb/C or Balb nu/nu(nude) mice. When the tumors reached about 1 cm in diameter, mice were injected intraperitoneally with $^{57}Co$-vitamin $B_{12}$. Twenty-four hours later, the mice were sacrificed. Organs and tissues were removed, weighed, and activity per mg determined by gamma counter. Values represented cpm/mg tissue that was normalized to 20 grams body weight for each mouse. A wide variety of tumor types showed significant uptake and concentration of $^{57}Co$-vitamin $B_{12}$, as evidenced by tumor:tissue activity ratios. For many tissues of great importance in terms of background(bone, muscle, blood), the tumor:tissue activity ratios of uptake were high. These data strongly suggest that further efforts to evaluate the utility of radio labeled adducts of vitamin $B_{12}$ for clinical use in oncologic imaging are warranted.

• Development and Reproduction
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• v.2 no.1
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• pp.45-52
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• 1998

An enhncer detector line(EDL) having P[1ArB] insertion in X chromosome with expression of reporter gene (lacZ) in the polar cells and border cell of egg chamber was established and used to monitor the differentiation and migration of border cells during the oogenesis of Drosophila. differentiation of border cell from the anterior polar follicle cells was evident in stage-9 egg chamber of EDL149 which was characterized by migration of columnar follicle cells toward posterior of egg chamber surrounding the oocyte. Migration of border cells was observed in the stage-9 and -10 egg chambers. \beta -galactosidase activities were rapidly increased during the first 4 days after eclosion, and it coincided with the timing of border cell differentiation in the ovary during adult life. Homozygote of EDL149 showed some retardation of border cell migration , resulting absence of migration of some border cells in the anterior part of egg chamber or delayed migration of some border cells in the stage-10 egg chamber. These results suggest that the P[1ArB] of EDL149 is inserted at the locus of the structural gene required for the border cell migration. In addition to the expression in egg chambers, lacZ expression was also detected in the meiotic germ cells of testis and antenna, suggesting the possible requirement of the trapped gene function in these organ. this EDL and enhancer trapped gene might be useful for the study of developmentally regulated cell migration.

• Applied Microscopy
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• v.37 no.4
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• pp.219-230
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• 2007

The morphological effects of intranasal zinc sulfate(5% solution) irrigation on the mouse olfactory epithelium and the regeneration process of olfactory receptor cells following nasal irrigation were studied with scanning and transmission electron microscope. The results were as follows: 1. The septal epithelium except some basal cells was wholly detached from the basement membrane, during the first 6 to 24 hours after 5% zinc sulfate irrigation. 2. 3 days after $ZnSO_4$ treatment, two layered septal epithelium was formed from basal cells. And microvilli were observed in the apical epithelium of newly formed olfactory epithelial cells. 3. 5 days after treatment, a lot of centrosomes and basal bodies were observed in the olfactory receptor cells, and cilia were lined up between microvilli on the apical membrane of olfactory receptor cells. And immature olfactory knob was first observed in the newly formed olfactory receptor cells. Mature olfactory knob was observed 1 week after treatment. 4. There are very many mature olfactory knobs in the olfactory receptor cells 2 weeks after intranasal zinc sulfate irrigation. These results support that treatment with 5% zinc sulfate is a good experimental model for the regeneration of mammalian nervous tissues because this method could thoroughly detach the septal epithelium. During the regeneration of olfactory receptor cells, the surface membrane of the olfactory receptor cells widen the surface with the microvilli. Then cilia, which arranged in a line, substituted for the microvilli. The part of the surface membrane with cilia protruded and finally formed the olfactory vesicle.

• Development and Reproduction
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• v.13 no.4
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• pp.297-303
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• 2009

Implantation of blastocyst into the uterine endometrium is established by the existence of histologically and functionally prepared uterine endometrium. Doc-1, an oral cancer suppressor gene, is expressed under the control of steroid hormones and has been suggested as a proliferation regulator of endometrial cells. However, the role is not much clear and in this study we examined the expression modulation of Doc-1 in decidualizing cells in vitro. In vitro decidualization was performed in endometrial stroma cells using progesterone and estrogen. Until 24 hr after decidual induction the proliferation of stroma cell was significantly increased but decreased after then. On the other hand, most of the cells differentiated into decidual cell after 48 hr of induction. The Doc-1 protein was co-localized in a specific deciudal cells and colocalization rate was increased in a parallel manner with the induction time. Based on these results, it is suggested that Doc-1 expression is under the control of both steroid hormones and decidual signals, and Doc-1 protein is involved in suppression of the proliferation of decidualizing cells.

• Korean Journal of Social Welfare
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• v.35
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• pp.107-131
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• 1998

This study tried to formulate and operate an interdisciplinary case management team in Eun-Pyung Gu, Seoul. This was a part of an effort to promote efficiency of service delivery system for low-income elderly or the handicapped by linking. coordinating. and integrating various health and human services providers. In-depth qualitative analysis described the process of which the interdisciplinary case management team was formed, along with the process of the team operation. The interdisciplinary team consisted of home helpers, visiting nurses, and social workers from Health Center and Social Welfare Centers. Issues dealt with by the team include: 1) information exchange of clients' social, economic, and medical situations; 2) identification of types of service provision to clients; 3) clients' needs assessment and its prioritization; 4) assignment of a leading case manager for each case; 5) identification of problems and issues regarding integration of service delivery system The team approach to case management contributed to the systematic delivery of services to the elderly and the handicapped by avoiding service duplication and fragmentation. This study argued that public agency played a key role in constituting and operating the interdisciplinary case management team Suggestions for further studies were presented.