Suchergebnisse

A common problem with the in vivo therapeutic applications of cells is that cells can rapidly disappear into the circulatory system after an injection. Magnetic nanoparticles can be used to solve this problem. Bacterial magnetic nanoparticles were used in this study for targeting stem cells at a specific location within a microfluidic channel. Magnetic nanoparticles were isolated from Magnetospirillum sp. AMB-1 and delivered to endothelial progenitor cells (EPCs). Cellular uptake of magnetic nanoparticles and their functional feasibility was characterized in vitro. The environment of a human blood vessel was simulated using a microfluidic channel. Magnetic nanoparticle-incorporated EPCs were injected into a microchannel and the flow rate of cells was uniformly controlled by use of a syringe pump. EPCs were effectively targeted to a specific location within the microchannel by an external magnetic field (about 400 mT). About 40% of EPCs were efficiently targeted with a flow rate of 5 μl min−1 when 10 μg of magnetic nanoparticles were used per 104 cells. This microfluidic system provides a useful tool towards a better understanding of the behavior of magnetic nanoparticle-incorporated cells within the human circulatory system for clinical use. ; This work was supported by a grant from the Innovative Research Institute for Cell Therapy (No. A06-2260- B81505-06N1-15010A). J. A. Kim acknowledges the Seoul Science Fellowship supported by Seoul Metropolitan Government.

Work overload is often inevitable in the workplace and is known to have a negative impact on employees' attitudes and behaviors. In this study we explored the mechanism through which work overload is negatively related to employees' affective commitment and how the negative effect of work overload could be mitigated. Using data obtained from 269 employees in South Korea, our results show that positive psychological capital and work engagement serially mediated the negative relationship between work overload and affective commitment. In addition, the negative relationship between work overload and affective commitment was moderated by the extent to which an employee experienced compassion at work. Our findings extend knowledge of how work overload is associated with employees' affective commitment and shed light on the importance of helping employees experience compassion at work to alleviate the negative impacts of work overload. Theoretical and practical implications are discussed.

This study empirically examined the effect of the perception of corporate social responsibility (CSR) activities on job satisfaction, as mediated by compassion and positive emotions toward work. Data were collected from 232 employees working in manufacturing, financial, telecommunications, transportation, and service industries in South Korea. The results confirm that (a) there were positive relationships between the perception of CSR activities and compassion, and between compassion and job satisfaction; (b) there were positive relationships between positive emotions toward work and job satisfaction, and between the perception of CSR activities and job satisfaction; and (c) there was a serial multiple mediation effect of compassion and positive emotions toward work on the pathway from the perception of CSR activities to job satisfaction. Theoretical and practical implications are discussed.

Background This study set out to evaluate the effect of dose rate on normal tissues (the lung, in particular) and the variation in the treatment efficiency as determined by the monitor unit (MU) and energy applied in Linac-based volumetric arc therapy (VMAT) total marrow irradiation (TMI). Methods Linac-based VMAT plans were generated for the TMI for six patients. The planning target volume (PTV) was divided into six sub-volumes, each of which had their own isocenter. To examine the effect of the dose rate and energy, a range of MU rates (40, 60, 80, 100, 300, and 600 MU/min) were selected for 6, 10, and 15 MV. All the plans were verified by portal dosimetry. Results The dosimetric parameters for the target and normal tissue were consistent in terms of the energy and MU rate. The beam-on time was changed from 59.6 to 6 min for 40 and 600 MU/min. When 40 MU/min was set for the lung, the dose rate delivered to the lung was less than 6 cGy/min (that is, 90%), while the beam-on time was approximately 10 min. The percentage volume of the lung receiving 20 cGy/min was 1.47, 3.94, and 6.22% at 6, 10, and 15 MV, respectively. However, for 600 MU/min, the total lung volume received over 6 cGy/min regardless of the energy, and over 20 cGy/min for 10 and 15 MV (i.e., 54.4% for 6 MV). Conclusions In TMI treatment, reducing the dose rate administered to the lung can decrease the incidence of pulmonary toxicity. To reduce the probability of normal tissue complications, the selection of the lowest MU rate is recommended for fields including the lung. To minimize the total treatment time, the maximum MU rate can be applied to other fields. ; This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (no. 2017M2A2A7A02020641) and the National R&D Program for Cancer Control, Ministry of Health & Welfare, Republic of Korea (no. HA 16C0025).

Monitoring regional antibiotic resistance patterns of uropathogens are important for deciding suitable empirical antibiotics for urinary tract infections (UTIs) in children. This study aimed to investigate regional differences in antimicrobial susceptibility patterns of E. coli and Klebsiella spp. in children below 24 months old, diagnosed with their first episode of UTI, and to find factors associated with an increased risk for UTI caused by extended-spectrum β-lactamase (ESBL)-producing uropathogens. This was a retrospective cohort study of children diagnosed between 2011 and 2017 in four different hospitals located in four different regions of South Korea; regions A, B, C, and D. The government's big data repository was used to acquire data on regional antibiotic prescriptions. The pooled antimicrobial susceptibilities of E. coli and Klebsiella spp. (n = 2044) were as follows: ampicillin–sulbactam (61.0%), 3rd generation cephalosporin (3C) (82.8%), and trimethoprim–sulfamethoxazole (72.0%). Multivariate analysis showed that children diagnosed at hospital A (OR, 1.8; 95% confidence interval [CI], 1.2–2.6; P = 0.002) and every year that increased in the study period (OR, 1.1; 95% CI, 1.1–1.2; P < 0.001) were factors associated with an increased risk for UTIs with ESBL-producers. Regions A and B had significantly higher amounts of oral 3Cs prescribed compared to regions C and D (P = 0.009), which correlate with hospitals in the regions that had higher proportions of UTIs with ESBL-producing uropathogens (A and B vs. C and D, P < 0.001). Therefore, children in certain regions are at a higher risk for UTIs caused by ESBL-producers compared to other regions, which correlate with regions that had higher amounts of oral 3Cs prescribed.

Korean government has selected and stocked five type antigens of two clades as Korean national antigen bank having high possibility of introduction to Korea. We aimed to evaluate the efficacy of the clade 2.3.2.1c and 2.3.4.4c H5Nx vaccines from the Korean avian influenza (AI) national antigen bank for emergency preparedness for their potency and protective efficacy against lethal homologous and heterologous viruses in layer and breeder chickens practically. The PD(50) (dose of vaccine that protects 50% of chickens from viral challenge) of all vaccinated groups was >50, which was satisfied with minimum antigen requirement of OIE, and the PD(50) levels of the two vaccines differed depending on strain and chicken breed. In homologous challenge, all vaccinated groups exhibited 100% survival with no clinical symptoms and high levels of pre-challenge protective immunity (7.2–8.5 log(2)), although they did not completely prevent virus shedding. On the other hand, against heterologous virus challenge, vaccinated animals exhibited 62.5–80% survival with lower antibody titers (2.3–3.4 log(2)) and a longer period of virus shedding (14 days post infection [dpi]). Our results suggest that the clade 2.3.2.1c and 2.3.4.4c H5Nx vaccines are good candidates for emergency vaccination of commercial chickens and support the idea that close genetic matching between vaccine and challenge virus provides the best protection.

Background: South Korea's 2016 Report Card on Physical Activity for Children and Youth is the first assessment of physical activity according to the indicators set by Active Healthy Kids Global Alliance. Methods: National surveys were used as preferred sources of data. This was then supported by peer-reviewed papers and government reports identified by a systematic search of the literature written in English or Korean. A Research Working Group then graded indicators based on the collected evidence. Results: Each indicator was graded as follows: Overall Physical Activity, D-; Organized Sport and Physical Activity Participation, C-; Active Transport, C+; Sedentary Behavior, F; School, D; Government and Investment, C; Active Play, Physical Literacy, Family and Peers, and Community and Built Environment were graded INC (incomplete) due to lack of available evidence. Conclusions: Though the final grades of key indicators for South Korean children and youth are not satisfactory, increasing interests and investments have been demonstrated at a national level. More evidence is required for comprehensive assessment on all indicators to better inform policy and practice. This should be accompanied by the use of consistent criteria to contribute to global efforts for active healthy kids. ; OAIID:RECH_ACHV_DSTSH_NO:T201623355 ; RECH_ACHV_FG:RR00200001 ; ADJUST_YN: ; EMP_ID:A074766 ; CITE_RATE:1.884 ; DEPT_NM:체육교육과 ; EMAIL:kys0101@snu.ac.kr ; SCOPUS_YN:Y ; CONFIRM:Y

To reduce the environmental burden caused by the disposal of spent nuclear fuel, waste burden minimization technology is currently being developed at the Korea Atomic Energy Research Institute. The technology includes a nuclide management process that can maximize disposal efficiency by selectively separating and collecting major nuclides in spent nuclear fuel. To manufacture a waste form of high durability, the characteristics of the waste generated during the process should be evaluated. In this study, the physical, radiological, and thermal characteristics of the waste and waste forms for major nuclides (Cs, Sr, I, transuranic/rare earth, and Tc/Se) generated in the nuclide management process were analyzed. In the case of Cs nuclides, characterization was conducted according to the capture rate of the adsorbent in the high-temperature heat treatment process; meanwhile, in the case of Sr nuclides, characterization was performed by considering the ratio of similar nuclides in the chlorination process. For I nuclide, analysis was performed based on the available waste form, and for TRU/RE and Tc/Se nuclides, analysis was performed by considering chlorination and mid-temperature heat treatment. The radioactivity and heat generation rate of each waste and waste form were evaluated over a period of 1,000 years. The results of this study could be used to derive the centerline temperature for the thermal stability evaluation of waste forms and for the feasibility evaluation of each disposal system considered in the waste burden minimization technology.