• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.344-357
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• 2020

Strain improvement and bioprocess development were undertaken to enhance hyaluronic acid(HA) production by Streptococcus zooepidemicus cells. Using a high-yielding mutant strain, statistical medium optimization was carried out in shake flask cultures, resulting in 52% increase in HA production (5.38 g/l) at the optimal medium composition relative to the parallel control cultures. For sufficient supply of dissolved oxygen (DO), which turned out to be crucial for enhanced production of HA, agitation system and speed were intensively investigated in 5 L bioreactor cultures. Increase in oxygen mass transfer coefficient (k_La) through increment of agitation speed (rpm) and 35% expansion of diameter of the newly-designed impellers showed significantly positive effects on HA production. By installing an expanded Rushton-turbine impeller for efficient break-down of sparged air, and an extended marine impeller above the Rushton-turbine impeller for efficient mixing of the air-born viscous fermentation broth, maximum amount of HA (9.79 g/l) was obtained at 450 rpm, 1.8 times higher level than that of the corresponding flask culture. Subsequently, the possibility of bioprocess scale-up to a 50 L bioreactor was investigated. Despite almost identical maximum HA production (9.11 vs 9.25 g/l), the average HA volumetric productivity (r_p) of the 50 L culture turned out only 74% compared to the corresponding 5 L culture during the exponential phase, possibly caused by shear damages imposed on the producing cells at the high stirring in the 50 L culture. The scale-up process could be successfully achieved if a scale-up criterion of constant oxygen mass transfer coefficient (k_La) is applied to the 50 L pilot-scale bioreactor system.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.848-855
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• 2008

Purpose : The objective of this study was to ascertain the incidence of congenital heart disease in the western part of Gyeongnam Province in Korea. Methods : We enrolled 849 children (M:F=390:459) who were diagnosed with congenital heart disease (CHD) and received echocardiography during January 1997 to December 2005 in Gyeongsang National University Hospital. The subjects were limited to patients born from 1997 to 2004. The CHDs were classified into acyanotic types and cyanotic type. Further, acyanotic type CHDs were divided into shunt type and valvular types. Results : Numbers of initially diagnosed patients from 1997 to 2004 were as follows: 113, 128, 116, 104, 129, 97, 84, and 78. The median age of initially diagnosed CHD patients was 1 month in the acyanotic type and 0.5 months in cyanotic type. Also, an annual frequency among CHD types and gender ratio were no significant difference in every year. Incidences of CHD from 2000 to 2004 in the western part of Gyeongnam Province were 8.9, 12.7, 10.9, 10.0, and 9.7 per 1,000 live births, respectively. Conclusion : From 1997 to 2001, 100-130, and from 2002 to 2004, less than 100 patients were diagnosed with CHD. This showed a decrease in the numbers of CHD patients in the last three years. However, the Incidence of CHD was 0.89-1.24% during the last five years. Therefore, the decrease in the annual frequency of CHD was due to the recent decline in birth rate in Korea.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.5
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• pp.101-115
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• 2017

This study analyzed the effects of social support on entrepreneurial opportunity competence for Baby boomer (born in 1955-1963), focusing on mediating effect of entrepreneurial self-efficacy. The governmental start-up policy and entrepreneurship education are mostly conducted for the college students and young generation mainly through such programs as the youth start-up school. In addition, studies on the effects of social support and institutional support on the entrepreneurial intention of young generation entrepreneurs are being actively pursued. Meanwhile, the study for baby boomers is on the welfare side mainly. Although they are starting to make their living-based business without prior careful preparation for their livelihood after retirement, while there is little study on the effect of social support for this baby boomer on entrepreneurial opportunity competence needed for opportunistic entrepreneurship. Therefore, in this study, in order to investigate the effect of social support on Baby boomer's entrepreneurial opportunity competence, an empirical analysis of the 387 questionnaires collected by the baby boomers living in Seoul and Gyeonggi provinces were conducted. As a result of analysis, First, Social support has a significant effect on both Opportunity recognition and Opportunity assessment of entrepreneurial opportunity competence. Second, In the effects of social support on self-efficacy were found to be significant in Emotional and Instrument support only on Self-confidence, In Emotional support and Feedback support only on Self-regulated efficacy & Emotional support and Instrument support only on Goal challenge were found to be a significant effect. Third, Self-regulated efficacy and Goal challenge in the Entrepreneurial self-efficacy on Entrepreneurial opportunity recognition were found to be a significant effect. All Self-confidence, Self-regulated efficacy & Goal challenge in the Entrepreneurial self-efficacy on Entrepreneurial opportunity assessment were found to be a significant effect. Fourth, Indirect effect of social support on entrepreneurial opportunity competence mediated by Entrepreneurial self-efficacy was found to be partially significant.

• Neonatal Medicine
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• v.16 no.1
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• pp.47-54
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• 2009

Purpose: Present evidences suggest that Ureaplasma urealyticum is a cause of pneumonia, septicemia, and bronchopulmonary dysplasia (BPD) in newborn infants, particularly those born prematurely. The purpose of this work was to examine the relationship between Ureaplasma urealyticum in the tracheal aspirates and adverse outcomes, such as BPD and early onset neonatal sepsis in premature infants. Methods: A polymerase chain reaction (PCR) was performed on tracheal aspirates collected within 24 hour after birth in 176 premature infants less than 35 weeks of gestation and admitted to the neonatal intensive care unit of Bundang CHA Hospital. Results: U. urealyticum was detected in 37 of 176 preterm infants (21.0%). Gestational age ($29^{+5}{\pm}2^{+5}$ wk vs. $30^{+6}{\pm}2^+{-5}$ wk, P=0.0l3) and birth weight (1.39${\pm}$0.44 kg vs. 1.59${\pm}$0.55 kg, P=0.037) were lower in the U urealyticum-positive group compared to the control group. The incidence of early onset neonatal sepsis (16.2% vs. 6.5%, P=0.045) and BPD (45.9% vs. 29.5%, P=0.047) was higher in the U urealyticum-positive group compared to the control group, but the severity of BPD was not different between two groups. However, multiple logistic regression analysis revealed that the presence of U. urealyticum was not independently related to the development of early onset neonatal sepsis and BPD. Conclusion: The results suggest that colonization of the lower respiratory tract by U. urealyticum might not be related to the development of neonatal sepsis and BPD directly in preterm infants.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.4
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• pp.466-475
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• 2005

Docosahexaenoic acid (22:6n-3, DHA) is highly enriched in membrane of brain and retina, and plays an important role in maintaining an optimal function of the central nervous system. We investigated the effect of n-3 fatty acid deficiency on rat brain, retina and liver fatty acyl composition at two different ages (3 wks and 15 wks) under DHA deficient condition. Rat pups born to dams fed a diet with $3.1\%$ of total fatty acids as $\alpha-linolenic$ acid (LNA) were fed using an artificial rearing system either an n-3 deficient (n-3 Def) or n-3 adequate (n-3 Adq) diet. Both diets contained $17.1\%$ linoleic acid (LA) but the n-3 Adq diet also contained $3.1\%$ LNA. Rats consuming the n-3 Def diet showed a lower brain $(50\%\;in\;13\;wks\;and\;70\%\;in\;15\;wks,\;p<0.05)$ and retinal $(50\%\;in\;13\;wks\;and\;63\%\;in\;15\;wks,\;p<0.05)$ DHA than those on the n-3 Adq diet, which was largely compensated for by an increase in docosapentaenoic acid (22:5n-6, DPAn-6). In the liver of the n-3 Def group, the percentage of DHA decreased by $97\%$ at 3 wks of age with an apparent increase in DPAn-6 relative to the n-3 Adq group (p<0.05), while there was a $65\%$ lower liver DHA in n-3 Def group at 15 wks of age than the n-3 Adq group (p<0.05). Liver arachidonic acid (20:4n-6, AA) was increased at 3 wks of age but decreased at 15 wks of age in the n-3 Def group compared with n-3 Adq group (p<0.05). In conclusion, the replacement of DHA by DPAn-6 in brain and retina fatty acid composition may be related to the suboptimal function in spatial learning, memory and visual acuity. This artificial rearing method presents a first generation model for n-3 deficiency that is similar to the case of human nutrition that commonly employed two generation model.

• Journal of Animal Science and Technology
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• v.53 no.4
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• pp.333-339
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• 2011

The present study was performed to investigate the effects of pre- and post-weaning feeding programs on growth of pigs. A total of 24 litters (avg. 10.6 piglets/litter) born from multiparous (Yorkshire ${\times}$ Landrace) dams ${\times}$ Duroc sires were provided with neither creep feed (CF) nor milk replacer ("CON"), 200 gm CF/litter/d from the 15th day of lactation ("MIN"), or CF and milk replacer ad libitum for 7 h during the daytime from the 7th day ("MAX") through weaning at d 21 of age. Sixty-eight weanling pigs selected randomly from each of CON and MIN were provided with phases 1, 2 and 3 nursery diets for 7, 14, and 13 days, respectively, in two pens; an equal number of piglets from MAX received the same diets for 6, 10, and 18 days, respectively. Subsequently, all pigs were fed grower 1 and 2 diets sequentially up to d 95 and 135, respectively. The entire pre- and post-weaning feeding trial was repeated three times under a split-plot design of experiment. Initial and final weights and ADG of the suckling pigs did not differ between MAX/MIN and CON. However, final wt of MAX adjusted for initial wt, which was 0.17-kg less in MAX than in CON, was greater than that of CON by 0.31kg, whereas the difference between MIN and CON in final wt barely changed after the adjustment. Growth of the animals during the nursery and growing phases was not affected by the feeding program, whereas d 55 and 135 BW, as well as d 6 BW, were highly correlated with weaning weight (r=0.81, 0.57, and 0.76; P<0.001, <0.05, and <0.001, respectively). In conclusion, results suggest that provision of creep feed and milk replacer from early lactation may be effective for increasing weight gain of light piglets, but that limited provision of creep feed during late lactation or extension of the duration of phases 1 and 2 vs. 3 nursery diets for several days is unlikely to influence the growth of pigs during the corresponding and subsequent periods.

• Journal of Embryo Transfer
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• v.21 no.2
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• pp.137-146
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• 2006

The objective of this study was to examine the effect of donor cell types, the source of recipient oocytes and estrous synchronization on pregnancy and delivery rates of somatic cell nuclear transfer (SCNT) embryos in Korean native goats. Recipient oocytes were surgically collected after superovulation. Ear cells and fetal fibroblasts were collected and cultured in serum-starvation condition (TCM-199 + 0.5% FBS) for cell confluence. The zonae pellucidae of in vivo- and in vitro-matured oocytes were partially drilled using a laser system. Single somatic cell was transferred into the enucleated oocyte. The reconstructed oocytes were electrically fused with 0.3 M mannitol. After the fusion, embryos were activated by Ionomycin+6-DMAP. NT embryos were cultured in mSOF medium supplemented with 0.8% BSA at $39^{\circ}C$ in an atmosphere of 5% $CO_2$, 5% $O_2$, 90% $N_2$ for 12 to 20 hr. One hundred and two SCNT embryos were transferred into 20 recipients and pregnancy rate at days 30 was 20.0%. Of them, one developed to term and delivered 1 kid. Ear cells showed significantly higher fusion (63.8 vs. 26.5%) and pregnancy rates (20.0 vs. 0.0%) than those of fetal fibroblast (p<0.05). The recipients synchronized by CIDR showed significantly lower pregnancy rates compared to that of recipient in natural estrus ($0.0{\sim}25.0%$ vs. 100%) (p<0.05). Cloned kid was born from the recipient in natural estrus. For the synchronization of estrus between recipient and donor, there was no difference between treatments (${\pm}0$ vs. +12 hr) in pregnancy rate. The first healthy cloned kid (Jinsoonny) was produced by transfer of SCNT embryos derived from in vivo oocytes and ear cells into a recipient goat whose estrus was synchronized with the donor. These results imply that donor cells for nuclear transfer may affect the success rate, and the estrus synchronization between donor and recipient animals can also be important.

• Clinical and Experimental Pediatrics
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• v.48 no.4
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• pp.369-375
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• 2005

Purpose : Many inborn errors of metabolism can be completely cured with early detection and early treatment. This is why neonatal screening on inborn errors of metabolism is implemented worldwide. In this study, a cost-benefit analysis was performed on the neonatal screening of phenylketonuria and congenital hypothyroidism in Korea. Methods : This study included 2,908,231 neonates who took the neonatal screening on phenylketonuria and congenital hypothyroidism in Korea from January 1991 to December 2003. From those neonates, the incidence rates of phenylketonuria and congenital hypothyroidism were measured. Furthermore, based on 495,000 babies born in 2002, were calculated and compared the total costs in case when neonatal screening on phenylketonuria and congenital hypothyroidism is implemented, and when not. Results : If the neonatal screening on phenylketonuria and congenital hypothyroidism is implemented, benefits far exceed costs at a ratio of 1.77 : 1 in phenylketonuria, and 11.11 : 1 in congenital hypothyroidism. In terms of wons, the present neonatal screening on phenylketonuria and congenital hypothyroidism will gain us more than 29 billion wons every year. Conclusion : This study only concerns the monetary aspects of the neonatal screening. Therefore, the benefits of the neonatal screening is underestimated by ignoring precious but not measurable values such as quality of life. However, the present neonatal screening on phenylketonuria and congenital hypothyroidism is found to be beneficial and should continue for the good of the nation as well as that of the patients.

• Clinical and Experimental Pediatrics
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• v.56 no.10
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• pp.439-445
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• 2013

Purpose: Previous studies suggest that the concentration of 25-hydroxyvitamin D [25(OH)D] in cord blood may show an inverse association with respiratory tract infections (RTI) during childhood. The aim of the present study was to examine the influence of 25(OH)D concentrations in cord blood on infant RTI in a Korean birth cohort. Methods: The levels of 25(OH)D in cord blood obtained from 525 Korean newborns in the prospective COhort for Childhood Origin of Asthma and allergic diseases were examined. The primary outcome variable of interest was the prevalence of RTI at 6-month follow-up, as diagnosed by pediatricians and pediatric allergy and pulmonology specialists. RTI included acute nasopharyngitis, rhinosinusitis, otitis media, croup, tracheobronchitis, bronchiolitis, and pneumonia. Results: The median concentration of 25(OH)D in cord blood was 32.0 nmol/L (interquartile range, 21.4 to 53.2). One hundred and eighty neonates (34.3%) showed 25(OH)D concentrations less than 25.0 nmol/L, 292 (55.6%) showed 25(OH)D concentrations of 25.0-74.9 nmol/L, and 53 (10.1%) showed concentrations of ${\geq}75.0$ nmol/L. Adjusting for the season of birth, multivitamin intake during pregnancy, and exposure to passive smoking during pregnancy, 25(OH)D concentrations showed an inverse association with the risk of acquiring acute nasopharyngitis by 6 months of age (P for trend=0.0004). Conclusion: The results show that 89.9% of healthy newborns in Korea are born with vitamin D insufficiency or deficiency (55.6% and 34.3%, respectively). Cord blood vitamin D insufficiency or deficiency in healthy neonates is associated with an increased risk of acute nasopharyngitis by 6 months of age. More time spent outdoors and more intensified vitamin D supplementation for pregnant women may be needed to prevent the onset of acute nasopharyngitis in infants.

• Journal of Food Hygiene and Safety
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• v.32 no.3
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• pp.206-210
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• 2017

This study was performed to develope mathematical models for predicting growth kinetics of Staphylococcus aureus in the processed meat product, pyeonyuk. Growth patterns of S. aureus in pyeonyuk were determined at the storage temperatures of 4, 10, 20, and $37^{\circ}C$ respectively. The number of S. aureus in pyeonyuk increased at all the storage temperatures. The maximum specific growth rate (${\mu}_{max}$) and lag phase duration (LPD) values were calculated by Baranyi model. The ${\mu}_{max}$ values went up, while the LPD values decreased as the storage temperature increased from $4^{\circ}C$ to $37^{\circ}C$. Square root model and polynomial model were used to develop the secondary models for ${\mu}_{max}$ and LPD, respectively. Root Mean Square Error (RMSE) was used to evaluate the developed model and the fitness was determind to be 0.42. Therefore the developed predictive model was useful to predict the growth of S. aureus in pyeonyuk and it will help to prevent food-born disease by expanding for microbial sanitary management guide.