• Development and Reproduction
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• v.16 no.4
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• pp.353-361
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• 2012

Human embryonic stem (ES) cells are a potential source of cells for developmental studies and for a variety of applications in transplantation therapies and drug discovery. However, human ES cells are difficult to culture and maintain at a large scale, which is one of the most serious obstacles in human ES cell research. Culture of human ES cells on MEF cells after disassociation with accutase has previously been demonstrated by other research groups. Here, we confirmed that human ES cells (H9) can maintain stem cell properties when the cells are passaged as single cells under a feeder-free culture condition. Accutase-dissociated human ES cells showed normal karyotype, stem cell marker expression, and morphology. We prepared frozen stocks during the culture period, thawed two of the human ES cell stocks, and analyzed the cells after culture with the same method. Although the cells revealed normal expression of stem cell marker genes, they had abnormal karyotypes. Therefore, we suggest that accutase-dissociated single cells can be usefully expanded in a feeder-free condition but chromosomal modification should be considered in the culture after freeze-thawing.

• Proceedings of the Zoological Society Korea Conference
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• 1999.04a
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• pp.76.1-76
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• 1999

No Abstract, See Full Text

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2001.08a
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• pp.37-47
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• 2001

No Abstract, See Full-text

• Journal of the Ergonomics Society of Korea
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• v.26 no.1
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• pp.103-109
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• 2007

Representative human models (RHMs), a group of digital human models which represent the people of the target population within a designated percentage (e.g., 95%), are used for ergonomic design and evaluation in virtual environments. The present study evaluated the grid approach, a RHM generation method, in terms of accommodation percentage. RHMs generated from the grid approach dramatically decreased the accommodation percentage of the target population as the number of anthropometric dimensions under consideration increased. For example, the accommodation percentages by RHMs generated by the grid approach were 95% for 3 key dimensions (selected among 10 anthropometric dimensions), 45% for 5 dimensions, and 10% for 10 dimensions. A standardized multiple regression analysis found that this decreasing accommodation percentage was caused by low correlations between key dimensions and other dimensions. The accommodation evaluation process used in the present study is applicable to evaluation of other RHM generation methods.

• Korea journal of population studies
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• v.14 no.1
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• pp.1-25
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• 1991

The Purpose of this study is to analyze the contribution of the total human capital formation to economic growth in Korea. In order to assess the contribution of the total human capital formation to economic growth, aggregate production functions are estimated using two ways of ordinary least squares and polynomial distributed lags based on 1955 - 1988 time series data in Korea. The total amount of investment in human capital is calculated by adding each amount of investment in formal education, vocational training, inter-provincial migration, and health in pecuniary terms. The findings of this study could be summarized as follows ; (1) If we enumerate the variables in good order according to the importance, we get the following ; namely, total number of labor force, inter-provincial migration, vocational training, health, physical capital, and formal education. (2) The contribution of the human capital to economic growth is much more larger than that of physical capital. In particular, it appears that inter-provincial migration and vocational training make a great contribution to economic growth. (3) It appears that investment in formal education has a continuous effect for fifteen years and maximum effect is observed approximately eight years later. In the case of vocational training, the effect of investment lasts for about 12-14 years and its effect on economic growth reaches maximum with the passage of seven to eight years after initial investment. (4) Investment in vocational training contributes more in the long run compared with investment in formal education. The effect of investment in formal education lasts longer than that of vocational training, while the effect of investment in vocational training is considerably larger in the short run compared with the investment in formal education.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1521-1525
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• 2014

Background: Human papillomavirus (HPV) is one of the most common sexually transmitted infections worldwide and the association between HPV infection and genital cancers has been well established. This study concerned the possible role of HPV infection in colorectal carcinoma (CRC) in the Iranian population. Materials and Methods: We examined 80 tissues obtained from patients with colorectal cancer consisting of 58 colon cancer samples and 22 rectal cancer samples and 80 tissues from patients with unremarkable pathologic changes as matched controls by sex, study center and anatomical sites. HPV infection and genotypes were detected using nested PCR and sequencing methods, respectively. Results: HPV DNA was detected in 5/80 (6.25%) cases including 1 of 22 (4.54%) patients with rectum cancer and 4 of 58 (6.9%) patients with colon cancer and 1/80 (1.25%) of controls. Furthermore, HPV-18 was detected as the most frequent type and we found no significant correlation between prevalence of HPV infection and anatomical sub- sites. Conclusions: Although a causal relation between human papillomavirus and colorectal cancer was not found through this study, analysis of medical records pointed to a possible role for high- risk types of HPV in increasing the potential of aggressiveness in colorectal cancer. This study shows a particular frequency of HPV genotypes in patients with colorectal cancer in Iran. Since HPV vaccines are limited to a few types of virus, using cohort studies in different geographical zones to screen for patterns of HPV infection in different organs might increase the efficacy and optimization of the current vaccines.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.3
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• pp.991-996
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• 2015

Side population (SP) cells have stem cell-like properties with a capacity for self-renewal and are resistant to chemotherapy and radiotherapy. Therefore the presence of SP cells in human breast cancer probably has prognostic value. Objective: To investigate the characteristics of SP cells and identify the relationship between the SP cells levels and clinico-pathological parameters of the breast tumor and disease-free survival (DFS) in breast cancer patients. Materials and Methods: A total of 122 eligible breast cancer patients were consecutively recruited from January 1, 2006 to December 31, 2007 at Yunnan Tumor Hospital. All eligible subjects received conventional treatment and were followed up for seven years. Predictors of recurrence and/or metastasis and DFS were analyzed using Cox regression analysis. Human breast cancer cells were also obtained from fresh human breast cancer tissue and cultured by the nucleic acid dye Hoechst33342 with Verapami. Flow cytometry (FCM) was employed to isolate the cells of SP and non-SP types. Results: In this study, SP cells were identified using flow cytometric analysis with Hoechst 33342 dye efflux. Adjusted for age, tumor size, lymph nodal status, histological grade, the Cox model showed a higher risk of recurrence and/or metastasis positively associated with the SP cell level (1.75, 1.02-2.98), as well as with axillary lymph node metastasis (2.99, 1.76-5.09), pathology invasiveness type (1.7, 1.14-2.55), and tumor volume doubling time (TVDT) (1.54, 1.01-2.36). Conclusions: The SP cell level is independently associated with tumor progression and clinical outcome after controlling for other pathological factors. The axillary lymph node status, TVDT and the status of non-invasive or invasive tumor independently predict the prognosis of breast cancer.

• Genomics & Informatics
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• v.3 no.3
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• pp.74-79
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• 2005

The H19 gene, located at human chromosome 11p15.5, is imprinted in most normal human tissues. However, imprinting is often lost in tumors suggesting H19 is a putative tumor suppressor. We analyzed the single nucleotide polymorphisms (SNPs) of a 16 kb region that includes the H19 gene and its imprinting control region (ICR) in the Korean population. To identify SNPs, we directly sequenced this region in 18 Korean subjects. We identified 64 SNPs, of which 7 were in the exons of H19, 2 were in the introns, 14 were in the 3' intergenic region and 41 were in the 5' intergenic region. Of the 64 SNPs, 21 had not previously been reported and thus appear to be unique to the Korean population. The identified SNPs of H19 in the Korean population may eventually be useful as genetic markers associated with various diseases. In this study, 7 of the 64 identified SNPs were at CTCF binding sites in the ICR and may affect regulation of H19 gene imprinting. Thus, several genetic variations of the H19 gene may be important markers in human diseases that involve genomic imprinting, including cancer.

• Parasites, Hosts and Diseases
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• v.39 no.2
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• pp.185-192
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• 2001

To evaluate the factors that determine the transmission level of vivax malaria using vectorial capacity, entomological surveys were conducted from .lune to August, 2000. From 6 nights of human-bait collection in Paju, the human biting rate (ma) was counted as 87.5 bites/man/night. The parity of Anopheles sinensis from human baiting collections fluctuated from 41% to 71% (average 48.8%) of which the rate gradually increased as time passed on: 35.2% in Jun. ; 55.0% in July; 66.2% in Aug. From this proportion of parous, we could estimate the probability of daily survival rate of An. sinensis to be 0.79 assumed with 3 days gonotrophic cycle and the expectancy of infective life through 11 days could be defined as 0.073. Blood meal analysis was performed using ELISA to determine the blood meal source. Only 0.8% of blood meals were from human hosts. We could conclude that An. sinensis is highly zoophilic (cow 61.8%) Malaria is highly unstable (stability index < 0.5) in this area. From these data, vectorial capacity VC) was determined to be 0.081. In spite of a high human biting rate (ma), malaria transmission potential is very low due to a low human blood index. Therefore, we could conclude that malaria transmission by An. sinensis is resulted by high population density, not by high transmission potential. For this reason, we need more effort to decrease vector population and vector-human contact to eradicate malaria in Korea.

• Safety and Health at Work
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• v.9 no.3
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• pp.257-264
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• 2018

Background: This paper presents the findings of a pilot research survey which assessed the degree of balance between safety and productivity, and its relationship with awareness and communication of human factors and safety rules in the aircraft manufacturing environment. Methods: The study was carried out at two Australian aircraft manufacturing facilities where a Likert-scale questionnaire was administered to a representative sample. The research instrument included topics relevant to the safety and human factors training provided to the target workforce. The answers were processed in overall, and against demographic characteristics of the sample population. Results: The workers were sufficiently aware of how human factors and safety rules influence their performance and acknowledged that supervisors had adequately communicated such topics. Safety and productivity seemed equally balanced across the sample. A preference for the former over the latter was associated with a higher awareness about human factors and safety rules, but not linked with safety communication. The size of the facility and the length and type of employment were occasionally correlated with responses to some communication and human factors topics and the equilibrium between productivity and safety. Conclusion: Although human factors training had been provided and sufficient bidirectional communication was present across the sample, it seems that quality and complexity factors might have influenced the effects of those safety related practices on the safety-productivity balance for specific parts of the population studied. Customization of safety training and communication to specific characteristics of employees may be necessary to achieve the desired outcomes.