• The Korean Journal of Pain
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• v.32 no.4
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• pp.245-255
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• 2019

Stem cells are attracting attention as a key element in future medicine, satisfying the desire to live a healthier life with the possibility that they can regenerate tissue damaged or degenerated by disease or aging. Stem cells are defined as undifferentiated cells that have the ability to replicate and differentiate themselves into various tissues cells. Stem cells, commonly encountered in clinical or preclinical stages, are largely classified into embryonic, adult, and induced pluripotent stem cells. Recently, stem cell transplantation has been frequently applied to the treatment of pain as an alternative or promising approach for the treatment of severe osteoarthritis, neuropathic pain, and intractable musculoskeletal pain which do not respond to conventional medicine. The main idea of applying stem cells to neuropathic pain is based on the ability of stem cells to release neurotrophic factors, along with providing a cellular source for replacing the injured neural cells, making them ideal candidates for modulating and possibly reversing intractable neuropathic pain. Even though various differentiation capacities of stem cells are reported, there is not enough knowledge and technique to control the differentiation into desired tissues in vivo. Even though the use of stem cells is still in the very early stages of clinical use and raises complicated ethical problems, the future of stem cells therapies is very bright with the help of accumulating evidence and technology.

• Journal of Medicine and Life Science
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• v.15 no.2
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• pp.46-50
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• 2018

Cancer, a leading mortality disease following cardiovascular disease worldwide, has high incidence as one out of every four adults in Korea. It was known to be caused by several reasons including somatic mutation, activation of oncogene and chromosome aneuploidy. Cancer cells show a faster growth rate and have metastatic and heterogeneous cell populations compared to normal cells. Cancer stem cells, the most invested field in cancer biology, is a theory to explain heterogeneous cell populations of cancer cells among several characteristics of cancer cells, which is providing the theoretical background for incidence of cancer and treatment failure by drug resistance. Cancer stem cells initially explain heterogeneous cell populations of cancer cells based on the same markers of normal stem cells in cancer, in which only cancer stem cells showed heterogeneity of cancer cells and tumor initiating ability of leukemia. Based on these results, cancer stem cells were reported in various solid cancers such as breast cancer, liver cancer, and lung cancer. Breast cancer stem cells were first reported in solid cancer which had tumor initiating ability and further identified as anti-cancer drug resistance. There were several identification methods in breast cancer stem cells such as specific surface markers and culture methods. The discovery of cancer stem cells not only explains heterogeneity of cancer cells, but it also provides theoretical background for targeting cancer stem cells to complete elimination of cancer cells. Many institutes have been developing new anticancer drugs targeting cancer stem cells, but there have not been noticeable results yet. Many researchers also reported a necessity for improvement of current concepts and methods of research on cancer stem cells. Herein, we discuss the limitations and the perspectives of breast cancer stem cells based on the current concept and history.

• International Journal of Stem Cells
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• v.16 no.1
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• pp.44-51
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• 2023

Background and Objectives: DNA methyltransferases (Dnmts) play an important role in regulating DNA methylation during early developmental processes and cellular differentiation. In this study, we aimed to investigate the role of Dnmts in neural differentiation of embryonic stem cells (ESCs) and in maintenance of the resulting neural stem cells (NSCs). Methods and Results: We used three types of Dnmt knockout (KO) ESCs, including Dnmt1 KO, Dnmt3a/3b double KO (Dnmt3 DKO), and Dnmt1/3a/3b triple KO (Dnmt TKO), to investigate the role of Dnmts in neural differentiation of ESCs. All three types of Dnmt KO ESCs could form neural rosette and differentiate into NSCs in vitro. Interestingly, however, after passage three, Dnmt KO ESC-derived NSCs could not maintain their self-renewal and differentiated into neurons and glial cells. Conclusions: Taken together, the data suggested that, although deficiency of Dnmts had no effect on the differentiation of ESCs into NSCs, the latter had defective maintenance, thereby indicating that Dnmts are crucial for self-renewal of NSCs.

• Journal of The Korean Association For Science Education
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• v.32 no.1
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• pp.30-45
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• 2012

Educational communities around the world have concentrated on integrative efforts among science, technology, engineering and mathematics (Science, Technology, Engineering, and Mathematics: STEM) subjects. Korea has focused on integrative education among STEAM (Science, Technology, Engineering, Arts, and Mathematics) school subjects to raise talented human resources in the fields of science and technology. The purpose of this study was to analyze secondary school science, technology, and mathematics teacher's perceptions and needs toward integrated education and integrative STEM education. A total of 251 secondary school teachers from all areas of the country who have taught science, mathematics, and technology were surveyed by using a self-reported instrument. The findings were as follows: First, teachers have used little integrated education in their classes due to insufficient time in the actual preparation of the integrated education and the lack of expertise, teaching experience, and teaching-learning materials for the integrated education, while they have positive thoughts about the need of integrated education. Second, they presented several needs to facilitate the integrated education: development of a variety of integrated programs, school administrative and financial support, and in-service teachers' training. Third, overall perception toward integrated STEM education was not sufficient, but most teachers perceived the need toward integrated STEM education due to students' development in their creativity, thinking skills, and adaptability. Fourth, they perceived that it was imperative to develop the various integrated STEM education programs, distribute the materials, and help STEM teachers' understanding toward integrated STEM education. Fifth, they perceived that the most relevant method to integrate STEM subjects was the problem solving approach. In addition, they appreciate that the integrated STEM education is highly efficient in not only developing integrated problem solving skills and STEM related literacy, but also in positively impacting the rise of talented human resources in the fields of science and technology. In order to increase the awareness of STEM-related secondary school teachers and vitalize the integrated STEM education, it is necessary to develop and spread a variety of programs, effective teaching and learning materials, and teachers' training programs.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.60-65
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• 2017

This study was conducted to dentify the optimum plantlet type of 'Solara' potatoes (Solanum tuberosum L.) for growth in an aeroponics system. Plantlets of 'Solara' were transplanted on March 16, 2015 in a greenhouse, and growth and yield characteristics were investigated at 70 and 78 days after transplanting, respectively. Stem length was shorter in plantlet of 15-day-old stem cuttings and acclimatization of culture, and the stem length of plantlets of stem cuttings tended to increase with increasing stem cutting age. The fresh weight of plants was the highest in the plantlets of 40-day-old stem cuttings and the lowest in non-rooted stem cuttings and acclimatization of culture. The highest number of first stolons was obtained in 35-day-old stem cuttings. The number of second stolons was the highest in plantlets of 35-day-old stem cuttings, acclimatization of culture, and 30- day-old stem cuttings. The total number of tubers was higher in plantlets of 35-day-old stem cuttings and acclimatization of culture, and the number of tubers above 3 g was the highest in plantlets of 35-day-old stem cuttings. The weight of tubers above 3 g was the heaviest in plantlets of 35-day-old stem cuttings(1,947 g per 10 plants), followed by plantlets of 30-day-old stem cuttings. These results indicate that plantlets of 30 to 35-day-old stem cuttings could be the best for production of 'Solara' potato tubers in an aeroponics system.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.2
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• pp.169-176
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• 2023

In this study, stem cells were extracted from the callus derived from the aloe cambium, and the antioxidant activity and effect of skin elasticity improvement were assessed. The aloe cambium-derived stem cell extract, AloStem and callus showed the survival rate of each 98.27% and 71.31%. In the results of the DPPH antioxidant activity of AloStem and aloe extract, it was confirmed that the antioxidant effect of AloStem was more than twice that of Aloe extract. AloStem did not affect the cytotoxicity of normal human dermal fibroblasts (NHDF) cells up to 0.25% concentration. Also, AloStem increased elastin, COL1A1 and HAS2 mRNA expression levels dose-dependently. Furthermore, to examine lifting effect of skin elasticity using a sheet mask containing AloStem, 21 adult men and women applied the sheet mask in the face, once a day for 2 weeks. As a result, after 2 weeks the skin length was 116.75 ± 5.58 mm before the use of the sheet mask, but after 2 weeks of use, it was confirmed that 0.59% increased to 117.44 ± 5.17 mm. Thus, we concluded that the sheet mask containing AloStem can help the lifting effect of skin elasticity.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.245-248
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• 1997

Excessive stress on the bone-stem interface may cause local micromotion that could produce midthigh pain, interface bone resorption and prevent bony ingrowth. It is important for clinician and prosthetic designer to develop an understanding of the load transfer mechanism, its associated stress pattern and its relationships with the particular mechanical characteristics of the femoral stem designs. Finite element method (FEM) is preeminently suited to provide information in this respect. The authors developed 3-dimensional numerical finite element models implanted with the straight stem which is composed of total 1170 elements of 8 nodes and with the curved stem which is composed of total 885 elements of 8 node, and analysed the relative micromotions between the straight stem and the curved stem in immediate postoperative stage of an uncemented total hip replacement in load simulating the single leg stance. The results showed that the rotational displacement was occupied over 90% of total micromotion in both types of stem and was peak at the proximal medial portion of the stem, but markedly less distally. The curved stem was more stable especially in terms of rotational stability. It is recommended that surgeons do not allow the patient weight bearing until bony ingrowth was achieved. In the future more attention should be drawn to increase initial rotational stability of the two types of femoral stem to prevent loosening from excessive micromotion.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.2
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• pp.133-141
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• 2008

Stem cells have self-renewal capacity, long-term viability, and multiline age potential. Adult bone marrow contains mesenchymal stem cells. Bone marrow-derived mesenchymal stem cells (BMSCs) are progenitors of skeletal tissue components and can differentiate into adipocytes, chondrocytes, osteoblasts, and myoblasts in vitro and undergo differentiation in vivo. However, the clinical use of BMSCs has presented problems, including pain, morbidity, and low cell number upon harvest. Recent studies have identified a putative stem cell population within the adipose tissue. Human adipose tissue contains pluripotent stem cells simillar to bone marrow-derived stem cells that can differentiate toward the osteogenic, adipogenic, myogenic, and chondrogenic lineages. Human adipose tissue-derived stem cells (ATSCs) could be proposed as an alternative source of adult bone marrow stem cells, and could be obtained in large quantities, under local anesthesia, with minimal discomfort. Human adipose tissue obtained by liposuction was processed to obtain ATSCs. In this study, we compared the osteogenic differentiation of ATSCs in a specific osteogenic induction medium with that in a non-osteogenic medium. ATSCs were incubated in an osteogenic medium for 28 days to induce osteogenesis respectively. Osteogenic differentiation was assessed by von Kossa and alkaline phosphatase staining. Expression of osteocyte specific bone sialoprotein, osteocalcin, collagen type I and alkaline phosphatase, bone morphogenic protein 2, bone morphogenic protein 6 was confirmed by RT-PCR. ATSCs incubated in the osteogenic medium were stained positively for von Kossa and alkaline phosphatase staining. Expression of osteocyte specific genes was also detected. Since this cell population can be easily identified through fluorescence microscopy, it may be an ideal source of ATSCs for further experiments on stem cell biology and tissue engineering. The present results show that ADSCs have an ability to differentiate into osteoblasts. In the present study, we extend this approach to characterize adipose tissue-derived stem cells.

• Journal of the Korean School Mathematics Society
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• v.16 no.2
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• pp.337-362
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• 2013

The purposes of the study were to develop STEM instructional materials for teaching and learning mathematics and to investigate how the STEM based approach affects on students' learning of mathematics in cognitive and affective domain and career choice. STEM instructional materials were designed for learning of mathematical concepts in the contexts of science, technology, and engineering as well as real world. According to the results of the study, STEM instructional materials for teaching and learning mathematics were effective for improving students' problem solving ability and affective achievement such as self-regulation, self-efficacy, and value of mathematics. In addition, STEM program played a positive role in tempting students' career choice into science and engineering fields including mathematics.

• Journal of Ginseng Research
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• v.31 no.3
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• pp.142-146
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• 2007

This experiment was conducted to find identification of ginseng root's age using the number of stem vestiges in rhizome. The number of stem vestiges in rhizome is a useful key to confirm the age of ginseng root as follow : 4-year-old root has two, 5-year-old root has three, 6-year-old root has four. The distribution of stem vestiges in rhizome each year root are as follow : 2 stem vestiges in 4-year-old root is 89.5%, 3 stem vestiges in 5-year-old root is 79.7%, 4 stem vestiges in 6-year-old root is 46.3%. However, the limiting factors of identification of ginseng root's age using the number of stem vestiges in rhizome is appearance of multi-stem per plant and appearance of destroyed stem vestige in rhizome. The ratio of appearance of multi-stem per plant and destroyed stem vestige in rhizome are increased according to root age.