• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.541-547
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• 2003

Purpose : Gap junction intercellular communication(GJIC) is an important mechanism of the bystander effect in herpes simplex thymidine kinase/ganciclovir(HSVtk/GCV) gene therapy Therefore, we attempted to enhance the bystander effect in vitro by exogenous overexpressing connexin 37(Cx37) in cells to increase GJIC. Methods : NIH3T3 cells were transfected with the Cx37 and HSVtk gene or the HSVtk gene alone by the calcium phosphate method, and we detected their expression from these cells by RT-PCR. GCV-mediated cytotoxicity and the bystander effect of each transfectant was then assessed and compared. Results : Cells transfected with HSVtk became sensitive to low concentration of GCV. We found significantly increased cytotoxicity in HSVtk/GCV gene therapy after introduction of the HSVtk and Cx37 genes together compared with the cytotoxicity seen after introduction of the HSVtk gene in vitro. Co-expression of the HSVtk and Cx37 genes potentiates HSVtk/GCV gene therapy through the bystander effect. Conclusion : These results indicated that the increase of GJIC using Cx37 have potentiated the bystander effect of HSVtk/GCV therapy, and may be a new approach to improve response in suicidal cancer gene therapy.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.319-326
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• 2001

The biological and physicochemical factors and geosmin concentration were monitored in the Daechung Reservoir for 25 weeks from April to October in 1999. Geosmin was detected 5 times within a range of $1.16{\sim}5.28\;ng\;L^{-1}$, mostly in the late summer. The highest geosmin concentration was recorded on August 31, which also overlapped with the peaks of phycocyanin concentration, cyanobacterial density, and Anabaena spiroides density. A correlation analysis indicated that geosmin production was closely related with a high water temperature, pH, total dissolved phosphorus (TDP), and A. spiroides density. A water temperature of $27^{\circ}^C$, pH of 8.5, and TDP of $0.06\;mg\;L^{-1}$ were identified as the prerequisite environmental condition sand threshold values for geosmin production. Accordingly, under such conditions, an A. spiroides density above $10,000\;cells\;mL^{-1}$ indicates imminent geosmin occurrence.

• Korean Journal of Clinical Laboratory Science
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• v.56 no.1
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• pp.1-9
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• 2024

Exosomes are nano-sized membrane-bound extracellular vesicles containing various biological molecules, such as nucleic acids, proteins, and lipids, which can be used to modulate physiological processes. The exosomal molecules secreted by cells can be extensively used as tools for diagnosis and therapy. Exosomes carry specific molecules released by the cells they originate from, which can be transferred to surrounding cells or tissues by the exosome. For these reasons, exosomes can be exploited as biomarkers for diagnosis, carriers for drug delivery, as well as therapeutics. In stem cell technology, exosomes have been an attractive option because they can be used as safer therapeutic agents for stem cell-based cell-free therapy. Recently, studies have demonstrated the safety and efficacy of mesenchymal stem cell-derived exosomes in alleviating symptoms associated with coronavirus disease 2019 as they have anti-inflammatory and immunomodulatory potential. Performing multiple studies on exosomes would provide innovative next-generation options for clinical diagnostics and therapy. This review summarizes the use of exosomes focusing on their diverse roles. In addition, the potential of exosomes is illustrated with a focus on how exosomes can be exploited as powerful tools in the days to come.

• Journal of Animal Science and Technology
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• v.52 no.1
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• pp.17-22
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• 2010

The current study was undertaken to determine the effects of sex steroid hormones (estrogen, testosterone and 19-nortestosterone) on proliferation and differentiation of preadipocytes of female and male pigs. The preadipocytes were isolated from the backfat of new-born female and male pigs by collagenase digestion and cultured in the $CO_2$ incubator. The concentration of $10^{-7}M$ and 10-6M sex steroid hormones were treated to the cultured preadipocytes. Regarding the effects on preadipocytes proliferation, high concentration ($10^{-6}M$) of all the three hormones increased proliferation of female preadipocytes,and only estrogen and testosterone increased proliferation of male preadipocytes. Regarding the effects on preadipocyte differentiation, all the three hormones increased differentiation of pig preadipocytes, regardless of hormone concentrations and sex of preadipocytes. The degree of stimulation of cell differentiation by sex steroid hormones was greater than that of cell proliferation.

• Applied Microscopy
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• v.33 no.3
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• pp.243-250
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• 2003

Ultrastructural changes of the male germ cells and structure of spermatozoa in Paralichthys olivaceus were examined by means of the light and transmission electron microscopes. The spermatogonium has a large nucleus with a single nucleus with a single nucleolus in the interphase. Primary spermatocytes are identified by the formation of the synaptonemal complex in the karyoplasm. The secondary spermatocytes are more concentrated and contains numerous cell organelle in the cytoplasm. The nucleus of spermatid in spermiogenesis is more condensed in the karyoplasm, and show spherical structure in shape. Mitochondria of the spermatids are observed in the lower portion of the nucleus. The spermatozoon consists of the head, mid piece and tail. The acrosome is not observed in the head. Axial filaments of the flagellum consists of nine pairs of the peripheral microtubules and one pair of the central microtubules.

• KSBB Journal
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• v.8 no.5
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• pp.465-472
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• 1993

The comparison of the capabilities of cell growth of four different kinds of commercially available microcarriers was carried out by culturing anchorage-dependent animal cells, Vero-6, in a spinner flask. Using 3 g/l of Cytodex 3, the maximum final cell density was about $1.4{\times}10^6$ cells/ml and increased up to $2.0{\times}10^6$ cells/ml by increasing microcarrier concentration up to 5 g/l. The macroporous collagen microcarriers, VX-100, informatrix, and Cultispher-G showed the final cell concentration of $4{\times}10^6$ cells/ml, $2.1{\times}10^6$ cells/ml, and $3.2{\times}10^6$ cells/ml, respectively at the microcarrier concentration of 5g/1. According to this result, VX-100 showed better cell growth than informatrix and cultispher-G and also showed about 2 fold increase in final cell density comparing to Cytodex 3 solid bead. When the intermittent bead-to-bead transfer technique was introduced in the culture using Cytodex 3 bead and cultispher-G, the result was very successful and the cells grew out very well. The recovered cells by dissolving collagen microcarrier using collagenase enzyme were mostly viable and grew out very well on the surface of the fresh microcarriers.

• Applied Microscopy
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• v.37 no.4
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• pp.239-248
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• 2007

Alteration of temperature is one of cancer therapies. In general, severe hyperthermia(around $43^{\circ}C$) and hypothermia(around $18^{\circ}C$) trigger apoptosis through mitochondria, though the specific mechanism is still unknown. CC-t6 and GB-d1 cell lines, which were originally derived from human cholangiocarcinoma and gall bladder cancer, were established from a metastatic lymph node. To investigate the mechanism of metastatic cancer cell response to thermal stresses, hyperthermia($37^{\circ}C{\rightarrow}43^{\circ}C$) and hypothermia($37^{\circ}C{\rightarrow}17.4^{\circ}C$) were designed. Thermal stresses did not induce apoptosis but necrotic cell death. Any alterations of caspase-3, -9, cytochrome c, Bax, and Bcl-2 were not found in both hyperthermia and hypothermia exposed fells using western blot analysis. In the transmission electron microscopy, typical necrotic, but not apoptotic, changes were observed. These results suggest that temperature changes induce cell death through necrotic pathway in metastatic cancer in vitro, and it can be one of effective anticancer methods.

• Journal of Life Science
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• v.29 no.12
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• pp.1329-1336
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• 2019

Subventricular zone (SVZ) in the brain contains neural stem cells (NSCs) which self-renew and differentiate to neurons and glial cells during postnatal period and throughout adulthood. Since fate decision to either proliferation or differentiation has to respond to intracellular and extracellular conditions, many intrinsic and extrinsic factors are involved. Among them, mitochondria have been reported to participate in fate decision of NSCs. In our previous report, we showed that long-term treatment of a mitochondrial inhibitor rotenone greatly inhibited neurogenesis. In this study, we examined the effects of short-term treatment of rotenone on SVZ NSCs. We found that (1) even one-day treatment of rotenone significantly reduced neurogenesis and earlier time points seemed to be more sensitive to rotenone, (2) a number of Mash1+ transit amplifying cells was decreased by one-day treatment of rotenone, (3) short-term treatment of rotenone eliminated most of the differentiated Tuj1+ neurons and Olig2+ oligodendrocytes, while glial fibrillary acidic protein (GFAP)+ astrocytes were not affected, and (4) sulfiredoxin 1 (Srxn1) gene expression was increased after one-day treatment of rotenone, indicating activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway. All these results confirm that functional mitochondria are necessary during differentiation to neurons or oligodendrocytes as well as maintenance of neurons after differentiation. Also, these data suggest that temporary exposure to mitochondrial inhibitor such as rotenone might have long-term effects on neurogenic potential of NSCs.

• The Microorganisms and Industry
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• v.16 no.3
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• pp.20-25
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• 1990

면역계에는 조력T세포(helper T cell)와는 반대로 면역반응을 억제적으로 조절하는 것이 주 기능인 억제성 T세포(suppressor T cell)가 존배한다는 것이 아려져 있다. 이 억제성 T세포가 존재한다는 개념이 면역학및 임상의학에 준 영향은 매우 지대하여, 앨러지나 자가 면역질환 같은 질병은 억제성 T세포의 결핍으로, 그리고 면역 결핍증같은 질병은 T세포가 지나치게 활성화된 것으로 설명되기에 이르렀다. 한마디로 거의 모든 저하된 면역반응은 억제성 T세포와 연관하여 설명되었다. 그러나 억제성 T세포가 발견된지 근 20년이 되고 그에 관한 논문이 5000여편에 달하는 최근까지도 억제성 T세포 및 이들 세포가 만드는 억제성 T세포 인자에 대한 실체는 정확히 규명되지 못하고 있다. 오히려 억제성 T세포가 조력 T세포처럼 별개의 세포군으로 존재한다는 것을 부인하는 학자도 최근 나오게 되었다.(이 분야의 연구에서 나타난 문제점들이 정리되어 있음). 그러나 억제성 T세포의 존재를 부인하는 학자들도 T세포가 면역 반응의 억제에 관여한다는 사실, 적어도 그 현상 자체를 부인하지는 않았다. 다시말하면, 면역반응이 T세포에 의하여 억제되는 현상은 이미 수 천년의 논문을 통하여 입증되고 있다. 면역반응의 억제에 있어서 억제성 T세포및 억제성 T세포 인자의 역할은 앞으로의 연구를 통해 명확히 규명될 것이며, 정말 억제성 T세포가 있느냐 없느냐 하는 것은 이 총설의 주제가 아니다. 다만 여기서는 조력 T세포도 경우에 따라서는 면역반응의 억제에 관여한다는 최근의 연구결과를 간단히 소개하고자 한다.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.77-96
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• 1993

This in vitro study was undertaken to observe whether citric acid application aids the attachment and proliferation of human periodontal ligament cells to the root surfaces of periodontally diseased teeth. The roots were prepared so that the comparison could be made among the control healthy root surface, citric acid demineralized and non-demineralized root planted surfaces. Prior to the cell attachment experiment, each groups were prepared for scanning electron microscopic (SEM) examinations of root surface morphology, All specimens were fixed with phosphate buffered glutaraldehydes, postfixed with phosphate buffered osmium tetraoxide and stained with phosphate buffered tannic acid. dehydrated in ethanol, critical point dried, sputter coated with gold and examined under the SEM. In the cell attachement experiment, human cultured periodontal ligament cells at concentration to $4.5{\times}\;10^4\;cells/ml$ were seeded in each culture well which contained prepared roots and incubated for 30min 1, 2, 6, 12 and 24 hours at 37, 5% $CO_2$air incubator. Than the specimens were prepared for SEM examination using, the same methods as described above. In the cell proliferation experiment, $5{\times}\;10^4\;cells/ml$ cells were seeded incubated with the specimens for 6 hours. Then, all of the specimens were moved into fresh culture well and incubated for 24, 48, and 72 hours. The cell counting was done after trypsinization, under light microscope. The results were as follows. When viewed the surface morphology prior to the cell attachment, the non acid treated root planed surface displayed scaling striation and occasional bacteria and calculus. The citric acid treated specimens displayed little debris on the surface and funnel shaped orifices of dentinal tubules. There were no apparent differences in the morphology of cells attached to the control and experiment groups. However, in initial attachement, there was a slight more enhanced appearance in attachment in citric acid treated groups than other root surfaces. After 6 hours of incubation, most of the cells initiated the alteration of cell morphology from ovoid to spindle shapes. After 24 hours of incubation, most of the cells displayed proliferated appearance and connected with each other via numerous processes. In the cell proliferation experiments, there were statistically significant increased number of cells in citic acid treated groups than other groups.