• BMB Reports
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• v.46 no.8
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• pp.383-390
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• 2013

Mammalian neural stem cells (NSCs) are of particular interest because of their role in brain development and function. Recent findings suggest the intimate involvement of programmed cell death (PCD) in the turnover of NSCs. However, the underlying mechanisms of PCD are largely unknown. Although apoptosis is the best-defined form of PCD, accumulating evidence has revealed a wide spectrum of PCD encompassing apoptosis, autophagic cell death (ACD) and necrosis. This mini-review aims to illustrate a unique regulation of PCD in NSCs. The results of our recent studies on autophagic death of adult hippocampal neural stem (HCN) cells are also discussed. HCN cell death following insulin withdrawal clearly provides a reliable model that can be used to analyze the molecular mechanisms of ACD in the larger context of PCD. More research efforts are needed to increase our understanding of the molecular basis of NSC turnover under degenerating conditions, such as aging, stress and neurological diseases. Efforts aimed at protecting and harnessing endogenous NSCs will offer novel opportunities for the development of new therapeutic strategies for neuropathologies.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.224-230
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• 2006

Escherichia coli transcription termination factor Rho catalyzes the unwinding of RNA/DNA duplex in reactions that are coupled to ATP binding and hydrolysis. We report here the kinetic mechanism of presteady state ATP binding and hydrolysis by the Rho-RNA complex. Presteady state chemical quenched-flow technique under multiple turnover condition was used to probe the kinetics of ATP binding and hydrolysis by the Rho-RNA complex. The quenched-flow presteady state kinetics of ATP hydrolysis studies show that three ATPs are bound to the Rho-RNA complex with a rate of $4.4\;{\times}\;10^5M^{-1}s^{-1}$, which are subsequently hydrolyzed at a rate of $88s^{-1}$ and released during the initiation process. Global fit of the presteady state ATP hydrolysis kinetic data suggests that a rapid-equilibrium binding of ATP to Rho-RNA complex occurs prior to the first turnover and the chemistry step is not reversible. The initial burst of three ATPs hydrolysis was proposed to be involved in the initialization step that accompanies proper complex formation of Rho-RNA. Based on these results a kinetic model for initiation process for Rho-RNA complex was proposed relating the mechanism of ATP binding and hydrolysis by Rho to the structural transitions of Rho-RNA complex to reach the steady state phase, which is implicated during translocation along the RNA.

• The Korean Journal of Physiology
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• v.15 no.1
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• pp.9-18
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• 1981

For centuries, ginseng has been used for the therapeutic purpose in oriental herb medicine. Several studies have been conducted in the past to evaluate the effect of ginseng on erythropoiesis. However the results were controversial. We therefore attempted in the present studies to evaluate the effect of ginseng on the erythropoietic activity. In one series of experiments, the recovery pattern of peripheral blood(red cell count, hemoglobin content, hematocrit and reticulocyte count) was studied in posthemorrhagic anemic rabbits. After animals were maintained with normal(control group) or 1 gm% ginseng (experimental group) diet for 2 weeks, hemorrhagic anemia was induced by withdrawing blood equivalent to 25% of the total blood volume and then changes in peripheral blood were followed for following 30 days. In other series of experiments, we studied effect of ginseng on erythrokinetics using $^{59}Fe$. $^{59}Fe(10{\sim}40\;{\mu}Ci/animal)$ was injected intravenously after animals were fed with normal (control group) or 1 gm% ginseng(experimental group) diet for 2 weeks. And radioactivities in the blood compartments were measured at appropriate intervals for 15 days. Front these various erythrokinetic parameters were estimated. Results are summarized as follows: 1) Reticulocyte count was higher in the experimental group than in the control group after 2 weeks of administration of experimental diet. During the posthemorrhagic period, the reticulocyte count increased in both the control and experimental groups, but the increase appeared much earlier in the experimental group. 2) The posthemorrhagic recoveries of hematocrit, hemoglobin content and red cell count appeared to be faster in the experimental group as compaired with the control group. 3) The half life$(T_{1/2})$ of $^{59}Fe$ in the plasma was significantly(P<0.05) shorter in the experimental group(82.6 min, N=8) than in the control group(121 min, N=6). Plasma iron turnover (PIT) of the experimental group (1.78 mg/dl/24 hr.) was approximately 4 times greater than that of the control group(0.45 mg/dl/24 hr.). 4) The maximum red cell utilization(RC-U) was 82.1% in the experimental group ana 74.5% in the control group. Red cell iron turnover(RIT) of the experimental group(1.62 mg/dl/24 hr.) was slightly higher than that of the control group(0.35 mg/dl/24 hr). 5) Erythron turnover was significantly(p<0.05) greater in the experimental group(1.27 mg/dl/24 hr.) than in the control group(0.24 mg/dl/24 hr.). Marrow transit time of the experimental group(2.05 days) tended to he faster than that of the control group(2.84 days). These results suggest that the gingseng improves the recovery of posthemorrhagic anemia and stimulates the erythropoiesis in rabbits.

• The Journal of Korean Academic Society of Nursing Education
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• v.29 no.3
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• pp.302-318
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• 2023

Purpose: This study aimed to identify the variables related to the organizational silence of Korean hospital nurses and to examine the effect sizes of correlations between the related variables and sub-types of organizational silence. Methods: Relevant studies were searched through a systematic search in six Korean electronic databases (RISS, ScienceON, KCI, DBpia, e-Article, and KISS) using June 2022 as the end date. Thirteen studies were identified through a systematic review and eight of them were meta-analyzed. The correlation effect size r (ESr) for each related variable was calculated. Results: Twenty-two related variables were identified from the systematic review. Of them, organizational culture was the most frequently examined. Seven variables (three organizational, two leader-member exchange, and two consequences of organizational silence) were found eligible for the meta-analysis. The intention of turnover (ESr=.39; 95% confidence interval, 95% CI=.32 to .45) and leader-member exchange ("manager's leaderships" ESr=-.33, 95% CI= -.43 to -.21; "manager's inclination to reject negative feedback" ESr=.32, 95% CI=.23 to .39) had larger correlation effect sizes than the other variables that related to organizational silence, in particular, acquiescent silence, which had the largest correlation effect size among the three sub-types of organizational silence. Conclusion: These findings show that the intention of turnover and leader-member exchanges were the main factors that related to the organizational silence. This indicates that it is necessary to develop management and education programs, as well as communication systems that focus on reducing and managing organizational silence, especially acquiescent silence.

• Korean Journal of Child Studies
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• v.22 no.4
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• pp.189-199
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• 2001

The purpose of this study was to explore the relationship between caregivers' characteristic variables and quality of child care and to investigate the magnitude of the association between variables and quality of child care according to children's age. The following factors were suggested as the caregivers' characteristic variables: Total years of caregiving experience, educational level, job satisfaction, amounts of turnover, time for commuting, salary, pay step, years of work in charge of current children, perception on the recommended caregiver/child ratio. The results of the study were as follows : First, it was found that caregivers' salary, total years of caregiving experience, pay step, perception on the recommended caregiver/child ratio, age, and amounts of in-service program were significant among caregivers' variables. Second, when the caregivers' characteristic variables were examined in terms of children's age respectively, the effects of teacher-related variables to influence the child-care quality were significantly different according to children's age group.

• Journal of dental hygiene science
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• v.24 no.2
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• pp.71-83
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• 2024

Background: Dental hygienists, who play a vital role in promoting oral health, experience burnout due to various factors. This study aimed to identify these factors through a scoping review of the literature on burnout among dental hygienists in Korea to develop prevention and intervention strategies for burnout. Methods: The literature review was conducted following a scoping review protocol, which included five stages: identifying the literature question, identifying relevant studies, study selection, charting the data, summarizing, and reporting the results. Of the 352 documents initially reviewed, 35 were ultimately selected as final studies. These documents were analyzed to identify general characteristics and key variables related to burnout and to review the recommendations made by the studies. Results: Analysis of the final documents revealed that most studies published between 2013 and 2018 involved sample sizes ranging from 201 to 300 participants. Burnout-related characteristics include age, salary, work experience, and marital status. Emotional labor was the key variable most frequently identified, followed by intention to leave, job stress, job satisfaction, job involvement, and self-efficacy. Conclusion: This study suggests that strategies for preventing and intervening in burnout should be developed through both personal efforts and institutional measures. This approach will improve the work environment for dental hygienists and, consequently, enhance the quality of dental healthcare services.

• Journal of Korean Academy of Nursing Administration
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• v.23 no.1
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• pp.101-110
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• 2017

Purpose: This study aimed to identify research trends in the Journal of Korean Academy of Nursing Administration from 2013 to 2015. Methods: For this study, 171 articles were analyzed. Research designs, participants, research settings, sampling, and data analyses methods were reviewed using established analysis criteria. Keyword centrality and clusters were generated by keyword network analysis. Results: Most of studies used quantitative methods (82.5%), and sampling mainly focused on nurses (68.8%). The most commonly used data analyses methods were t-test, ANOVA, correlation, and regression. The most central keywords were turnover and empowerment. Network analysis generated four network groups: 1) burnout; 2) turnover; 3) happiness; and 4) nursing professionalism. Conclusion: The results of this study identify current trends and interests in Korean nursing administration research. The findings from this study suggest that future studies include a variety of research methods and maintain appropriate research ethics.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.93-103
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• 1999

Recent advances in the biotechnology of ruminal bacteria have been made in the characterization of enzymes involved in plant cell wall digestion, the exploration of mechanisms of gene transfer in ruminal bacteria, and the development of vectors. These studies have culminated in the introduction and expression of heterologous glucanase and xylanase genes and a fluoroacetate dehalogenase gene in ruminal bacteria. These recent studies show the strategy of gene and vector construction necessary for the production of genetically engineered bacteria for introduction into ruminants. Molecular research on proteolytic turnover of protein in the rumen is in its infancy, but a novel protein high in essential amino acids designed for intracellular expression in ruminal organisms provides an interesting approach for improving the amino acid profile of ruminal organisms.

• Mycobiology
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• v.39 no.4
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• pp.243-248
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• 2011

The ubiquitin-proteasome system is one of the major protein turnover mechanisms that plays important roles in the regulation of a variety of cellular functions. It is composed of E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 ubiquitin ligases that transfer ubiquitin to the substrates that are subjected to degradation in the 26S proteasome. The Skp1, Cullin, F-box protein (SCF) E3 ligases are the largest E3 gene family, in which the F-box protein is the key component to determine substrate specificity. Although the SCF E3 ligase and its F-box proteins have been extensively studied in the model yeast Saccharomyces cerevisiae, only limited studies have been reported on the role of F-box proteins in other fungi. Recently, a number of studies revealed that F-box proteins are required for fungal pathogenicity. In this communication, we review the current understanding of F-box proteins in pathogenic fungi.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.2 no.3
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• pp.61-102
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• 2007

This study empirically analyzed how human resource management(HRM) practices affect the performance of venture firms using The results of the study are as follows: First of all, several HRM practices were found to affect organizational performance significantly. Specifically, ${(1)}$ recruitment and selection practices were negatively related to turnover, which seemed to mean that effective staffing including development of good recruitment pools and rigorous selection process lower turnover, and ${(2)}$ training and development, compensation, and labor-management relations were positively related to subjective performance of the firms, which implied that as the venture firms provide more opportunities of training and development to employees, provide compensation on the basis of performance, and develop cooperative labor-management relations, the subjective performance of the venture firms Increases. Secondly, negative interaction effects were found to exist between competitive strategies and HRM practices on organizational performance. Specifically, ${(1)}$ the interaction between differentiation strategy and compensation were significantly related to turnover, ${(2)}$ HRM planning and training and development interacted with differentiation strategy to significantly affect subjective organizational performance, and ${(3)}$ HRM planning, selection, training and development, compensation and communication practices interacted with technology innovation strategy to affect subjective organizational performance. So far, there have not been many studies which deal with HRM practices of venture firms in Korea. Thus, it is hoped that this study stimulate more research efforts on theory development and empirical studies on HRM practices of venture firms. Also, it is hoped that government conduct more policy studies and provide more resources in HRM area of the venture firms. Specifically, it is suggested that government take proactive steps to improve industrial skilled staff and technical researcher systems in order to alleviate the problems of workforce shortages in venture firms. And it IS also suggested that regional human resource development programs be introduced with the participation of the firms, local governments, and universities.