• International Journal of Oral Biology
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• v.45 no.4
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• pp.197-203
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• 2020

Mesenchymal stem cells in the dental pulp exhibit a tendency for differentiation into various dental lineages and hold great potential as a major conduit for regenerative treatment in dentistry. Although they can be readily isolated from teeth, the exact characteristics of these stem cells have not been fully understood so far. When compared to two-dimensional (2D) cultures, three-dimensional (3D) cultures have the advantage of enriching the stem cell population. Hence, 3D-organoid culture and 3D-sphere culture were applied to dental pulp cells in the current study. Although the establishment of the organoid culture proved unsuccessful, the 3D-sphere culture readily initiated the stable generation of cell aggregates, which continued to grow and could be passaged to the second round. Interestingly, a significant increase in SOX2 expression was detected in the 3D-spheroid culture compared to the 2D culture. These results indicate the enrichment of the stemness-high population in the 3D-sphere culture. Thus, 3D-sphere culture may act as a link between the conventional and 3D-organoid cultures and aid in understanding the characteristics of dental pulp stem cells.

• Journal of Korean Public Health Nursing
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• v.15 no.2
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• pp.225-238
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• 2001

The purpose of this study is to examine public health nurses for their morale, test the effect of each factor on the morale, determine the variables affecting the morale, and thereby, provide for some basic data useful to the development of personnel affair administration for nurses. The survey on the nurses for public health centers was conducted for 10 days from April 23 to May 2, 2001; 96 nurses from Pusan, 101 from Kyonggi-do and 108 from Kangwon-do. The results of the study are as follows; 1. For the demographic variables, those aged between 31 and 39 accounted for the majority $(50.2\%)$ of the sample. $90.8\%$ was married, and $67.9\%$ of the sample graduated from junior colleges. $29.6\%$ of them had worked for 10-14 years and $62.5\%$ was of the seventh rank. $62.3\%$ of the nurses was recruited, and $59.4\%$ had chosen the public job for its guaranteed status. Half the nurses were working for the county population of which was more than 260 thousands, and $53\%$ of the nurses was serving the public health centers with 11-15 members. $47.3\%$ of them perceived that their living standard is middle or lower. 2. The degree of the moral was found as mean score. 2.65, which is interpreted as low. It has 11 factors. The rank of mean score of the factors is job satisfaction (3.36), sense of belonging (3.36), sense of recognition (3.30), stress due to supervision (3.13), degree of participation (3.05) and self-achievement (3.04), while those scoring lower points were assurance of status (2.58), pay level (2.53), working conditions (2.35) and promotion opportunity (2.31). 3. The degree of moral depending on the demographic variables was significantly affected by such variables as age. academic background, career, rank, employment method, motive for the job, size of the population served and living standards. 4. The result of the Stepwise multiple regression analysis for the morale factors, it was found that self-achievement accounted for $61\%$ of the total variance of the degree of morale, followed by stable status $(18\%)$, working conditions $(8\%)$, job requirements $(4\%)$ and promotion opportunities $(2\%)$; these five factors explained about $94.6\%$ of total variance of the degree of nurses' morale. On the other hand. age $(8\%)$ and academic background $(2\%)$ accounted for $10\%$ of the total variance of the degree of morale. 5. The factors affecting nurses' job life was economic need $(26.7\%)$, personnel management $(17.5\%)$, sense of recognition $(13.2\%)$, human relationship $(11.0\%)$, stable status and personal development in rank. On the other hand, the factors influencing on their possible resignation were children's bringing-up $(27.8\%)$, poor personnel management and promotion $(13.3\%)$, workload $(11.1\%)$ and little personal development $(8.9\%)$, Since such morale factors as promotion opportunity, working condition. pay level and stable status scored lower, it is required to reconsider those factors to improve nurses' morale.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.169-176
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• 2010

A pilot-scale wastewater treatment plant combined with rotating biological contactor and tapered aeration reactors was operated with the wastewater discharged from a food factory for 5 months. The bacterial communities of this plant were investigated by terminal restriction fragment length polymorphism (T-RFLP) and phylogenetic analysis of 16S rRNA genes. In spite of high concentration of nitrogen and phosphorus as well as organic carbon, removal efficiency of chemical oxygen demand, total nitrogen, and total phosphorus was 98%, 93%, and 95%, respectively. Bacterial community at the initial operation stage was clearly distinguished from that of the stable operation stage. The most predominant phylum in the sample of stable stage was Bacteroidetes. Major population of operation period was Haliscomenobacter, Sphaerotilus, and candidate division TM7, which were classified as filamentous bacteria. However, sludge bulking caused by these bacteria was not observed. The population that has a close relationship with Haliscomenobacter increased during the stable operation stage, emerging as the most predominant group. These results suggest that the filamentous bacteria participated in nutrient removal when using rotating biological contactor and tapered aeration reactor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.605-610
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• 2001

We investigated the effects of salinity on an estuarine cladoceran, Diaphanosoma celebensis as a substitute live food organism of Artemia, which has been used for the next step of rotifer, in the course of seedling production of marine fishes, Culture density for growth, possibility of stable culture (RPGI: Relative Population Growth Index) and food feeding activity (RCN: Remaining Cell Numbers) of D. celebensis were investigated at intervals of 5 ppt under 10 steps of different saline conditions from 0 to 45 ppt. According to the results, the experimental group, which was regarded as the best condition of culture density for growth, stable culture possibility (RPGI) and good food feeding activity (RCN), was salinity culture condition of 20 put, and relative stable culture conditions were observed under saline concentrations $15\~35\;ppt$. Their functions under culture conditions of lower or higher salinities than 20 ppt appeared remarkably to be decreased, while all individuals were dead under the saline condition of 0 ppt after the beginning of the experiment. From these results of this study, it is assumed that estuarine cladoceran, D. celebensis can be cultured easily as a substitute live food organism of Artemia in the course of seedling production of marine fishes.

• Korea journal of population studies
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• v.18 no.2
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• pp.115-168
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• 1995

It is a common wisdom that the long-term economic development of Korea chiefly depends not only on the steady increase of the capital formation but also on the stable increase of the national saving. And also it is a widely accepted opinion that household saving plays a significant role for the smooth supply of investment funds. For the empirical analysis on the determining factors of household saving, consumption function of the household of Korea was utilized indirectly. The reason is that consumption function is regarded as a stable function whereas saving function is considered to be an unstable function of the relevant independent variables. In order to carry out the regression process of the consumption functions, data on the family income and expenditure survey and the farm household economy survey was used. The regression result could be summarized as follows : Firstly, household income and the number of the employed in the household have the negative effect in determining the consumption ratio of the Korean households. On the other hand, ages and the educational attainment of the household heads as well as the number of the household members have the positive effect. During the early part of 21st century, the consumption ratio of the Korean households is expected to be decreased because of the increasing trend of household income, and the ever increasing number of the employed member of the household based on the increasing trend of the labor force participation rate of women and the decrease of the average size of the number of household members owing to widespread nuclear family system. On the other hand, the consumption ratio of the household of Korea is expected to be increased because of the continuous increase of the average ages of the household heads caused by the population aging phenomena and improvement of the educational attainment of the household heads. But on the whole, household saving ratio is expected to be increased owing to the secular downward trend of the consumption and therefore no significant difficulties are anticipated for the smooth provision of investment resources needed to have long-term economic progress of Korea.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.9-15
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• 2011

The functional cardiovascular system is comprised of distinct mesoderm-derived lineages including endothelial cells, vascular smooth muscle cells and other mesenchymal cells. Recent studies in the human embryonic stem cell differentiation model have provided evidence indicating that these cell lineages are developed from the common progenitors such as hemangioblasts and cardiovascular progenitor cells. Also, the studies have suggested that these progenitors have a common primordial progenitor, which expresses KDR (human Flk-1, also known as VEGFR2, CD309). We demonstrate here that sustained activation of BMP4 (bone morphogenetic protein 4) in hESC line, CHA15 hESC results in $KDR^+$ mesoderm specific differentiation. To determine whether the $KDR^+$ population derived from hESCs enhances potential to differentiate along multipotential mesodermal lineages than undifferentiated hESCs, we analyzed the development of the mesodermal cell types in human embryonic stem cell differentiation cultures. In embryoid body (EB) differentiation culture conditions, we identified an increased expression of $KDR^+$ population from BMP4-stimulated hESC-derived EBs. After induction with additional growth factors, the $KDR^+$ population sorted from hESCs-derived EBs displays mesenchymal, endothelial and vascular smooth muscle potential in matrix-coated monolayer culture systems. The populations plated in monolayer cultures expressed increased levels of related markers and exhibit a stable/homologous phenotype in culture terms. In conclusion, we demonstrate that the $KDR^+$ population is stably isolated from CHA15 hESC-derived EBs using BMP4 and growth factors, and sorted $KDR^+$ population can be utilized to generate multipotential mesodermal progenitors in vitro, which can be further differentiated into cardiovascular specific cells.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1613-1620
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• 2012

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.

• Health Policy and Management
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• v.32 no.2
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• pp.205-215
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• 2022

Background: The purpose of this study is to identify the factors infecting the medical care utilization from a new perspective by newly classifying the categories of administrative districts using the urban decline index and medical vulnerability index as indicators. Methods: This study targeted 150,940 people who used medical services using the 2015 cohort database (DB), 2010-2015 urban regeneration analysis index DB, and 2014-2015 public health and medical statistics DB. The decline of the region was classified using the urban decline index typed using k-means clustering and the medical vulnerability index typed using the quantile score calculation. Regression analysis was performed 3 times with medical expenditure, length of stay, and the number of outpatient visits as dependent variables. Results: There were 37 stable region (47.4%), 29 health vulnerable region (37.2%), and 12 decline region (15.4%). The health vulnerable region had lower medical expenditure, fewer outpatient visits, and a higher length of stay than the stable region. The decline region was all higher than the stable region but had no significant effect. Conclusion: The factors that cause the health disparity between regions are not only factors related to individual health behavior but also environmental factors of the local community. Therefore, there is a need for a systematic alternative that properly considers the resources within the community and reflects the characteristics of the population.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1149-1156
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• 2008

The conformational study on neutral and zwitterionic L-alanines (N-Ala and Z-Ala, respectively) and the transition state (TS) for their interconversion is carried out using ab initio HF and density functional B3LYP methods with the self-consistent reaction field method in the gas phase and in solution. At both the HF and B3LYP levels of theory, the local minimum N1 for N-Ala is found to be most preferred in the gas phase and a weak asymmetric bifurcated hydrogen bond between the amino hydrogens and the carbonyl oxygen appears to play a role in stabilizing this conformation. The local minima N2a and N2b are found to be the second preferred conformations, which seem to be stabilized by a hydrogen bond between the amino nitrogen and the carboxylic hydrogen. The relative stability of the local minimum N2b is remarkably increased in solution than that in the gas phase. The local minimum N2b becomes more stable than the local minimum N2a in most of the solution. On the whole the relative free energies of Z-Ala and TS become more lowered, as the solvent polarity increases. N-Ala prevails over Z-Ala in aprotic solutions but Z-Ala is dominantly populated in ethanol and water. In aprotic solutions, the population of Z-Ala increases somewhat with the increase of solvent polarity. The barrier to Z-Ala-to-N-Ala interconversion increases on the whole with the increase of solvent polarity, which is caused by the increase of stability for Z-Ala.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.508-513
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• 2017

The complete genome sequence of a Slovak SL-1 isolate of Tomato mosaic virus (ToMV) was determined from the next generation sequencing (NGS) data, further confirming a limited sequence divergence in this tobamovirus species. Tomato genotypes Monalbo, Mobaci and Moperou, respectively carrying the susceptible tm-2 allele or the Tm-1 and Tm-2 resistant alleles, were tested for their susceptibility to ToMV SL-1. Although the three tomato genotypes accumulated ToMV SL-1 to similar amounts as judged by semiquantitative DAS-ELISA, they showed variations in the rate of infection and symptomatology. Possible differences in the intra-isolate variability and polymorphism between viral populations propagating in these tomato genotypes were evaluated by analysis of the capsid protein (CP) encoding region. Irrespective of genotype infected, the intra-isolate haplotype structure showed the presence of the same highly dominant CP sequence and the low level of population diversity (0.08-0.19%). Our results suggest that ToMV CP encoding sequence is relatively stable in the viral population during its replication in vivo and provides further demonstration that RNA viruses may show high sequence stability, probably as a result of purifying selection.