• The Korean Journal of Physiology and Pharmacology
• /
• v.18 no.2
• /
• pp.109-120
• /
• 2014

The epothilones are a class of microtubule inhibitors that exhibit a strong antitumor activity. UTD2 is a novel epothilone analog generated by genetic manipulation of the polyketide biosynthetic gene cluster. This study investigated the effects of UTD2 on the actin cytoskeleton and its critical regulators, and the signaling pathways which are essential for cell motility, growth and survival in MCF-7 breast cancer cells. Results showed that UTD2 inhibited the cellular functions of actin cytoskeleton, such as wound-closure, migration and invasion, as well as adhesion. Our study further demonstrated that UTD2 suppressed Rac1 GTPase activation and reduced the activity of PAK1, which is a downstream effector of Rac1, while the activity of Cdc42 was not affected. Additionally, the phosphorylation of p38 and ERK were significantly inhibited, but the phosphorylation of JNK remained the same after UTD2 treatment. Moreover, UTD2 inhibited the activity and mRNA expression of MMP-2, which plays a key role in cell motility. UTD2 also reduced the phosphorylation of Akt, which is an important signaling kinase regulating the cell survival through Rac1. Furthermore, UTD2 interrupted the synergy between Rac1 and Raf in focus formation assays. Taken together, these results indicated that UTD2 exerted multiple effects on the actin cytoskeleton and signaling pathways associated with Rac1. This study provided novel insights into the molecular mechanism of the antineoplastic and antimetastatic activities of epothilones. Our findings also suggest that the signaling pathways regulated by Rac1 may be evaluated as biomarkers for the response to therapy in clinical trials of epothilones.

• Korean Journal of Poultry Science
• /
• v.28 no.1
• /
• pp.69-76
• /
• 2001

Avian primordial germ cells (PGCs) originate from the epiblast and appear in the germinal crescent. These PGCs enter the developing blood vessels during stage 10∼12 (H&H), circulate in the blood stream, migrate into the developing gonadal anlage and differentiate into germ cells. However, it is not clear until when the migratory ability of PGC is maintained. This study was conducted to examine whether migratory ability is present in PGCs from the gonad at later embryonic developmental stages. In the present study, gonads were dissected from 5-, 6- and 10-day old quail embryos and treated with trypsin-EDTA. Gonadal PGCs (gPGCs) were purified by Ficoll-density-gradient-centrifugation and labeled with PKH26 fluorescent dye. The PKH26-labeled gPGCs were microinjected into the blood vessel of the recipient quail embryo. Manipulated recipients were incubated for 3 days, embedded in paraffin and sdctioned. The foreign gPGCs were detected by fluorescent and confocal laser microscopy. As a result, quail gPGCs, from 10, 6 and 5 day old embryos could migrate through the recipient blood stream at early stage and settle in the gonads. Thus, results suggest that gPGCs from upto 10-day old embryos keep properties seen in circulating PGC. Therefore, the PGCs of 10-day old embryonic gonads can be used for the tools of genetic manipulation.

• Journal of Science Education
• /
• v.38 no.3
• /
• pp.703-717
• /
• 2014

In physics, metal simulation is an important mechanism to understand and create concepts. If students have difficulty in mental simulation, understanding the concept of physics also gets difficult. By providing guide for spatial manipulation to students, 3D simulation contents can help them understand the concept of physics. In this study, the 3D simulation contents developed to help understanding the concept of light going straight and shadow is applied to 20 college students. The results, Hake gain is 0.93, showing high level of understanding about the class. In addition, through mental simulation, students predict the phenomenon well about the new context. This is shown that students' understanding of concept through 3D simulation contents are carried out well.

• Clinics in Shoulder and Elbow
• /
• v.13 no.2
• /
• pp.266-269
• /
• 2010

Purpose: We report case of neglected elbow dislocation for three years. Material and method: A 45 years old female patient presented with neglected elbow dislocation for three years. Since the patient had contracture in both lateral and medial collateral ligament of elbow, dissection was done. After total separation of posterior articular capsule and incision of anterior articular capsule, by manual manipulation, reduction of radiohumeral and ulnohumeral joints were obtained. We applied modified Morrey type hinged external fixation in the elbow and done early elbow exercise. Result and Conclusion: Since we have experienced a satisfactory result in the case with neglected elbow dislocation for 3 years by using open reduction and hinged external fixation, we report it with the literature.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1996.11a
• /
• pp.65-73
• /
• 1996

LPS/LOS, the compound found only in gram-negative bacterial outer membrane, plays important roles in bacterial maintenance as well as its pathogenesis. We isolated and characterized several genes required for NTHi 2019 LOS biosynthesis, which encode enzymes required for sugar substrate synthesis or the transfer of substrates to receptor molecules. The htrB gene, however, appears to have more complex role. It has acryltransferase activity as well as various other activity, which may control regulation of LOS biosynthesis as well as its pathogenicity. Evidences supporting the latter come from the observations that the lipid A of the B29 induced significantly less TNF ${\alpha}$ from macrophages than that of the wild type LOS (unpublished data). H. influenzae A2-htrB mutant strain was also significantly less invasive than the wild type strain. The structural similarities of the enterobacterial LPS and the Haemophilus LOS enabled us to isolate the NTHi 2019 genes involved in LOS biosynthesis genes by using the S. typhimurium LPS deep core mutants. While a similar approach has been used for E. coli, this technique for selection of an LPS phenotype has not been applied to nonenterobacterial species. The difficulties inherent in the molecular manipulation of organism such as Neisseria and Haemophilus species make this approach particularly attractive in the identification and cloning LOS genes. Studies on genetic features of LPS/LOS biosynthesis would be useful for understanding bacterial pathogenesis as well as for developing vaccines for these gram-negative pathogenic bacteria.

• Journal of Plant Biotechnology
• /
• v.30 no.1
• /
• pp.81-95
• /
• 2003

Carotenoids are synthesized from the plastidic glyceraldehyde-3-phosphate (GAP)/pyruvate pathway in isoprenoids biosynthetic system of plants. They play a crucial role in light harvesting, work as photoprotective agents in photosynthesis of nature, and are also responsible for the red, orange and yellow colors of fruits and flowers in plants. In addition to biological actions of carotenoids as antioxidants and natural pigments, they are essential components of human diet as a source of vitamin A. It has been also suggested that some kinds of carotenoids might provide protection against cancer and heart disease as human medicines. In this article, we review the commercial applications on the basis of biological functions of carotenoids, summarize the studies of genes involved in the carotenoid biosynthetic pathway, and introduce recent results achieved in metabolic engineering of carotenoids. This effort for understanding the carotenoids metabolism will make us to increase the total carotenoid contents of crop plants, direct the carotenoid biosynthetic machinery towards other useful carotenoids, and produce a new array of carotenoids by further metabolizing the new precursors that are created when one or two key enzymes in carotenoid biosynthetic pathway are exchanged through gene manipulation in the near future.

• The Mathematical Education
• /
• v.57 no.3
• /
• pp.231-246
• /
• 2018

In this paper, we applied Sfard's reification theory to analyze the secondary students' level of conceptualization with regard to the formula of quadratic equation. Through the generation and development of mathematical concepts from a historical perspective, Sfard classified the formulation process into three stages of interiorization, condensation, and reification, and proposed levels of formulation. Based on this theory, we constructed a test tool reflecting the reversibility of the nature of manipulation of Piaget's theory as a criterion of content judgement in order to grasp students' conceptualization level of the formula of quadratic equation. By applying this tool, we analyzed the conceptualization level of the formula of quadratic equation of the $9^{th}$ and $10^{th}$ graders. The main results are as follows. First, approximately 45% of $9^{th}$ graders can not memorize the formula of quadratic equation, or even if they memorize, they do not have the ability of accurate calculation to apply for it. Second, high school curriculum requires for students to use the formula of the quadratic equation, but about 60% of $10^{th}$ graders have not reached at the level of reification that they can use the formula of quadratic equation. Third, as a result of imaginarily correcting the error of the previous concept, there was a change in the levels of $9^{th}$ graders, and there was no change in $10^{th}$ graders.

• Archives of Reconstructive Microsurgery
• /
• v.11 no.2
• /
• pp.173-178
• /
• 2002

Wound healing is the result of interaction of normal cellular and biochemical responses that restore the interrupted anatomical structure in limited period. When any response of them is impaired, it results in chronic wound. The factors that influence the wound healing process is not only limited to the fundamental disease of the individual but also the local factors, especially various growth factors secreted from the various cells involved in tissue regeneration have important role. Recent reports that the chronic wounds are depleted of these growth factors have led active studies on the alteration of local wound environment with manipulation of the growth factors and the its application in management of chronic wounds. We investigated the effect on the chronic wounds in 10 patients with various pathologic conditions to suggest the appropriate application and guideline of the indication. The chronic wounds resulting from various causes in 10 patients were treated with rhPDGF gel and good wound care. All the chronic wounds were located on the lower extremity and the average diameter was 2.5 cm. 7 patients were completely cured within 8 weeks, however the patient who received previous radiation therapy the healing was delayed to 14 weeks. Two patients with vascular ulcer were not cured with rhPDGF alone. Local application of rhPDGF has yielded complete cure of the chronic wound in 70% of the patients within 2 months. The author suggests that it would be an effective alternative treatment modality of chronic wound when it is applied with good wound care and appropriate indication.

• School Mathematics
• /
• v.10 no.2
• /
• pp.297-317
• /
• 2008

This study was designed to gain insight to adopt CAS into secondary level algebra education in Korea. Most inactive usage of calculators in math and most negative effects of calculators on their achievements of Korean students were shown in International studies such as TIMSS-R. A comparative study was carried out with consideration of mathematical backgrounds and technological environments. 8 Korean students and 26 US students in Grade 11 were participated in this study. Subjects' Problem solving process and their strategies of CAS usage in classical Box-problem with CAS were analyzed. CAS helped modeling by providing symbolic manipulation commands and graphs with students' mathematical knowledge. Results indicates that CAS requires shifts focus in algebraic contents: recognition of decimal & algebraic presentations of numbers; linking various presentations, etc. The extent of instrumentation effects on the selection of problem solving strategies among Korea and US students. Instrumentation

• Journal of Embryo Transfer
• /
• v.23 no.2
• /
• pp.67-76
• /
• 2008

Since the birth of Dolly using fully differentiated somatic cells as a nuclear donor, viable clones were generated successfully in many mammalian species. These achievements in animal cloning demonstrate developmental potential of terminally differentiated somatic cells. At the same time, the somatic cell nuclear transfer (SCNT) technique provides the opportunities to study basic and applied biosciences. However, the efficiency generating viable offsprings by SCNT remains extremely low. There are several explanations why cloned embryos cannot fully develop into viable animals and what factors affect developmental potency of reconstructed embryos by the SCNT technique. The most critical and persuasive explanation for inefficiency in SCNT cloning is incomplete genomic reprogramming, such as DNA methylation and histone modification. Numerous studies on genomic reprogramming demonstrated that incorrect DNA methylation and aberrant epigenetic reprogramming are considerably correlated with abnormal development of SCNT cloned embryos even though its mechanism is not fully understood. The SCNT technique is useful in cloning farm animals because pluripotent stem cells are not established in farm animal species. Therapeutic cloning combined with genetic manipulation will help to control various human diseases. Also, the SCNT technique provides a chance to overcome excessive demand for the organs by production of transgenic animals as xenotransplantation resources. Here, we describe the factors affecting the efficiency of generating cloned farm animals by the SCNT technique and discuss future directions of animal cloning by SCNT to improve the cloning efficiency.