• Clinical and Experimental Reproductive Medicine
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• v.42 no.2
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• pp.33-44
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• 2015

The generation of artificial gametes is a real challenge for the scientific community today. In vitro development of human eggs and sperm will pave the way for the understanding of the complex process of human gametogenesis and will provide with human gametes for the study of infertility and the onset of some inherited disorders. However, the great promise of artificial gametes resides in their future application on reproductive treatments for all these people wishing to have genetically related children and for which gamete donation is now their unique option of parenthood. This is the case of infertile patients devoid of suitable gametes, same sex couples, singles and those fertile couples in a high risk of transmitting serious diseases to their progeny. In the search of the best method to obtain artificial gametes, many researchers have successfully obtained human germ cell-like cells from stem cells at different stages of differentiation. In the near future, this field will evolve to new methods providing not only viable but also functional and safe artificial germ cells. These artificial sperm and eggs should be able to recapitulate all the genetic and epigenetic processes needed for the correct gametogenesis, fertilization and embryogenesis leading to the birth of a healthy and fertile newborn.

• BMB Reports
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• v.51 no.9
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• pp.474-479
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• 2018

Cisplatin is one of the most effective chemotherapeutic drugs used in the treatment of HCC, but many patients will ultimately relapse with cisplatin-resistant disease. Used in combination with cisplatin, resveratrol has synergistic effect of increasing chemosensitivity of cisplatin in various cancer cells. However, the mechanisms of resveratrol enhancing cisplatin-induced toxicity have not been well characterized. Our study showed that resveratrol enhances cisplatin toxicity in human hepatoma cells via an apoptosis-dependent mechanism. Further studies reveal that resveratrol decreases the absorption of glutamine and glutathione content by reducing the expression of glutamine transporter ASCT2. Flow cytometric analyses demonstrate that resveratrol and cisplatin combined treatment leads to a significant increase in ROS production compared to resveratrol or cisplatin treated hepatoma cells alone. Phosphorylated H2AX (${\gamma}H2AX$) foci assay demonstrate that both resveratrol and cisplatin treatment result in a significant increase of ${\gamma}H2AX$ foci in hepatoma cells, and the resveratrol and cisplatin combined treatment results in much more ${\gamma}H2AX$ foci formation than either resveratrol or cisplatin treatment alone. Furthermore, our studies show that over-expression of ASCT2 can attenuate cisplatin-induced ROS production, ${\gamma}H2AX$ foci formation and apoptosis in human hepatoma cells. Collectively, our studies suggest resveratrol may sensitize human hepatoma cells to cisplatin chemotherapy via gluta${\gamma}H2AX$mine metabolism inhibition.

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.518-526
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• 2013

Gut-derived lipopolysaccharides (LPS) are critical to the development and progression of chronic low-grade inflammation and metabolic diseases. In this study, the effects of probiotics Lactobacillus and Bifidobacterium on gut-derived lipopolysaccharide and inflammatory cytokine concentrations were evaluated using a human colonic microbiota model. Lactobacillus reuteri, L. rhamnosus, L. plantarum, Bifidobacterium animalis, B. bifidum, B. longum, and B. longum subsp. infantis were identified from the literature for their anti-inflammatory potential. Each bacterial culture was administered daily to a human colonic microbiota model during 14 days. Colonic lipopolysaccharides, and Gram-positive and negative bacteria were quantified. RAW 264.7 macrophage cells were stimulated with supernatant from the human colonic microbiota model. Concentrations of TNF-${\alpha}$, IL-$1{\beta}$, and IL-4 cytokines were measured. Lipopolysaccharide concentrations were significantly reduced with the administration of B. bifidum ($-46.45{\pm}5.65%$), L. rhamnosus ($-30.40{\pm}5.08%$), B. longum ($-42.50{\pm}1.28%$), and B. longum subsp. infantis ($-68.85{\pm}5.32%$) (p < 0.05). Cell counts of Gram-negative and positive bacteria were distinctly affected by the probiotic administered. There was a probiotic strain-specific effect on immunomodulatory responses of RAW 264.7 macrophage cells. B. longum subsp. infantis demonstrated higher capacities to reduce TNF-${\alpha}$ concentrations ($-69.41{\pm}2.78%$; p < 0.05) and to increase IL-4 concentrations ($+16.50{\pm}0.59%$; p < 0.05). Colonic lipopolysaccharides were significantly correlated with TNF-${\alpha}$ and IL-$1{\beta}$ concentrations (p < 0.05). These findings suggest that specific probiotic bacteria, such as B. longum subsp. infantis, might decrease colonic lipopolysaccharide concentrations, which might reduce the proinflammatory tone. This study has noteworthy applications in the field of biotherapeutics for the prevention and/or treatment of inflammatory and metabolic diseases.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.220-223
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• 2003

In this paper, we optimize distributed autonomous robotic system based on artificial immune system. Immune system has B-cell and T-cell that are two major types of lymphocytes. B-cells take part in humoral responses that secrete antibodies and T-cells take part in cellular responses that stimulate or suppress cells connected to the immune system. They have communicating network equation, which have many parameters. The distributed autonomous robotics system based on this artificial immune system is modeled on the B-cells and T-cells system. So performance of system is influenced by parameters of immune network equation. We can improve performance of Distributed autonomous robotics system based on artificial immune system.

• Molecules and Cells
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• v.41 no.7
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• pp.639-645
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• 2018

Liver transplantation is recommended for patients with liver failure, but liver donors are limited. This necessitates the development of artificial livers, and hepatocytes are necessary to develop such artificial livers. Although induced hepatocyte-like cells are used in artificial livers, the characteristics of mouse induced hepatocyte-like cells (miHeps) reprogrammed with embryonic fibroblasts have not yet been clarified. Therefore, this study investigated the mechanisms underlying the survival, function, and death of miHeps. miHeps showed decreased cell viability, increased cytotoxicity, decreased hepatic function, and albumin and urea secretion at passage 14. Addition of necrostatin-1 (NEC-1) to miHeps inhibited necrosome formation and reactive oxygen species generation and increased cell survival. However, NEC-1 did not affect the hepatic function of miHeps. These results provide a basis for development of artificial livers using hepatocytes.

• Molecules and Cells
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• v.27 no.2
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• pp.167-173
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• 2009

The classical type of transient receptor potential (TRPC) channel is a molecular candidate for $Ca^{2+}$-permeable cation channels in mammalian cells. Because TRPC4 and TRPC5 belong to the same subfamily of TRPC, they have been assumed to have the same physiological properties. However, we found that TRPC4 had its own functional characteristics different from those of TRPC5. TRPC4 channels had no constitutive activity and were activated by muscarinic stimulation only when a muscarinic receptor was co-expressed with TRPC4 in human embryonic kidney (HEK) cells. Endogenous muscarinic receptor appeared not to interact with TRPC4. TPRC4 activation by $GTP{\gamma}S$ was not desensitized. TPRC4 activation by $GTP{\gamma}S$ was not inhibited by either Rho kinase inhibitor or MLCK inhibitor. TRPC4 was sensitive to external pH with $pK_a$ of 7.3. Finally, TPRC4 activation by $GTP{\gamma}S$ was inhibited by the calmodulin inhibitor W-7. We conclude that TRPC4 and TRPC5 have different properties and their own physiological roles.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.14-17
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• 1995

An in vitro construct of three dimensional artificial skin equivalent has been engineered using human cervical epithelial cells and human foreskin fibroblasts with a matrix of bovine type I collagen. Two cell lines were established from cervical uteri cancer tissues which have the HPV(human papillomavirus)18 genome. These two cell lines came from the same origin but have slight differencies in growth rate and tumorigenicity. The organotypic raft culturing of epithelial cells were accomplished at air-liquid interface. The differentiation related characteristics were examined by immunohistochemistry using monoclonal antibodies against EGFreceptor, cytokeratin 5/6/18 as proliferation markers and against filaggrin, involucrin, and cytokeratin 10/13 as differentiation marker. We have obtained the stratification and the differentiation in the artificial skin equivalent, and differentiation-related proteins were expressed more in the C3-artificial skin, and proteins of proliferation were expressed more in the C3N-artificial skin, relatively. We found that reconstituted artificial skin have the same characteristics of differentiation proteins of original tissue or cells of human body.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.1-5
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• 1998

One cervical cancer cell line, C9, carrying human papillomavirus type 18 (HPV18) genes that is one of the major etiologic concoviruses for cervical cancer was characterized. This cell line was further characterized for its capacity related to the epithelial cell proliferation, stratification and differentiation in reconstituted artificial epithelial tissue. The in vitro construction of three dimensional artificial cervical opithelial tissue has been engineered using C9 epithelial cancer cells, human foreskin fibroblasts and a matrix made of type I collagen by organotypic culture of epithelial cells. The morphology of paraffin embedded artificial tissue was examined by histochemical staining. The artificial epithelial tissues were well developed having multilayer. However, the tissue morphology was similar to the cervical tissus having displasia induced by HPV infection. The characteristics of the artificial tissues were examined by determinining the expression of specific marker proteins. In the C9 derived artificial tissues, the expression of EGF receptor, as epithelial proliferation marker proteins for stratum basale was observed up to the stratum spinosum. Another epithelial proliferation marker for stratum spinosum, cytokerations 5/6/18, were observed well over the stratum spinosum. For the differentiation markers, the expression of involucrin and filaggrin were observed while the terminal differentiation marker, cytokeratins 10/13 was not detected at all. Therefore the reconstituted artificial epithelial tissues expressed the same types of differentiation marker proteins that are expressed in normal human cervical epithelial tissues but lacked the final differentiation capacity representing characteristics of C9 cell line as a cancer tissue devived cell line. Expression of HPV18 E6 oncoprotein was also observed in this artifical cervical opithelial tissue though the intensity of the staining was weak. Thus this artificial epithelial tissue could be used as a useful model system to examine the relationship between HPV-induced cervical oncogenesis and epithelial cell differentiation.

• Journal of Embryo Transfer
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• v.24 no.3
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• pp.139-143
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• 2009

Most captive canids and felids at Zoos in advanced countries have been examined enough to apply artificial reproductive techniques to them. We investigated reproductive hormones and vaginal epithelial cells of a 6-year-old, female coyote, hoping these data could eventually be extended to artificial insemination with frozen-thawed conspecific semen at Seoul Zoo. As a relative of pet dogs, coyote exhibited a similar appearance with only minor differences. In vaginal smear, an increase in the number of superficial cells suggests that the bitch has reached a state close to estrus. A sudden decrease of estradiol and increase of progesterone is considered as a preovulatory event. Vaginal epithelial cells and hormones might be useful for determining the optimal time of artificial insemination in coyotes' breeding.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.299-302
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• 2006

A combinatorial library of artificial transcription factors (ATFs) was introduced into the bacterial cells that expressed the Akt1-GFP fusion protein. By measuring the level of fluorescence generated by the transformed E. coli cells, we were able to obtain clones in which ATFs increased the solubility of the Akt1. Our results show that ATF library is a useful tool for increasing the solubility of selected recombinant proteins in E. coli.