• Clinical and Experimental Pediatrics
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• v.53 no.3
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• pp.286-293
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• 2010

Peak bone mass is established predominately during childhood and adolescence. It is an important determinant of future resistance to osteoporosis and fractures to gain bone mass during growth. The issue of low bone density in children and adolescents has recently attracted much attention and the use of pediatric dual-energy X-ray absorptiometry (DXA) is increasing. The process of interpretation of pediatric DXA results is different from that of adults because normal bone mineral density (BMD) of children varies by age, body size, pubertal stage, skeletal maturation, sex, and ethnicity. Thus, an appropriate normal BMD Z-score reference value with Z-score should be used to detect and manage low BMD. Z-scores below -2.0 are generally considered a low BMD to pediatrician even though diagnoses of osteoporosis in children and adolescents are usually only made in the presence of at least one fragility fracture. This article will review the basic knowledge and practical guidelines on pediatric DXA based on the International Society for Clinical Densitometry (ISCD) Pediatric Official Positions. Also discussed are the characteristics of normal Korean children and adolescents with respect to BMD development. The objective of this review is to help pediatricians to understand when DXA will be useful and how to interpret pediatric DXA reports in the clinical practice for management of children with the potential to develop osteoporosis in adulthood.

• The Journal of Fisheries Business Administration
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• v.51 no.4
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• pp.85-96
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• 2020

The purpose of this study is to find out the determinants of export in Korean fishery products. For the analysis, laver and tuna, which account for almost half of seafood exports, were selected, and a gravity model widely used in trade analysis was applied. As explanatory variables, GDP, number of overseas Koreans, exchange rate, FTA, and WTO were applied, and fixed effect terms were included to take into account multilateral resistance that hinders trade. The analysis period is from 2000 to 2018, and the Poisson Pseudo Maximum Likelihood (PPML) method was applied to solve the problem of zero observation and heteroscedasticity inherent in trade data. As a result of the analysis, GDP was found to have a significant positive effect on both laver and tuna. The number of overseas Koreans was significant in canned tuna exports, but not in laver and the other tuna products. As the exchange rate increased, the export of laver and tuna for sashimi increased. The impacts of the FTA were confirmed in the exports of dried laver and raw tuna, which supports the results of the previous study. WTO was not significant for laver and tuna. Based on these results, it is necessary to find a way to make good use of the FTA to expand exports of seafood.

• Journal of the Korean Geotechnical Society
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• v.26 no.5
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• pp.37-48
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• 2010

In this study, the seepage flow monitoring method by the hydraulic head loss rate was developed for the purpose of application to offshore construction site enclosed by cofferdams in which seepage force varies periodically. The amount of the hydraulic head loss rate newly defined in this graph was in a range between 0 and 1. The zero of the rate means the existence of flow with no seepage resistance. The 1 of the rate means no seepage flow through the ground. The closer to 1 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows is stable. The closer to 0 the coefficient of determinant in the hydraulic head loss graph is, the more the ground through which seepage water flows was unstable and the higher the possibilities of existence of empty space or of occurrence of piping on the seepage flow pass in the ground is. The hydraulic head loss graph makes it possible to monitor sensitively the situation of seepage flow state, and the graph helps to understand easily the seepage flow state at the specific section on the whole cofferdam.

• Molecules and Cells
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• v.27 no.6
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• pp.673-680
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• 2009

Conversion of the normal soluble form of prion protein, PrP ($PrP^C$), to proteinase K-resistant form ($PrP^{Sc}$) is a common molecular etiology of prion diseases. Proteinase K-resistance is attributed to a drastic conformational change from ${\alpha}$-helix to ${\beta}$-sheet and subsequent fibril formation. Compelling evidence suggests that membranes play a role in the conformational conversion of PrP. However, biophysical mechanisms underlying the conformational changes of PrP and membrane binding are still elusive. Recently, we demonstrated that the putative transmembrane domain (TMD; residues 111-135) of Syrian hamster PrP penetrates into the membrane upon the reduction of the conserved disulfide bond of PrP. To understand the mechanism underlying the membrane insertion of the TMD, here we explored changes in conformation and membrane binding abilities of PrP using wild type and cysteine-free mutant. We show that the reduction of the disulfide bond of PrP removes motional restriction of the TMD, which might, in turn, expose the TMD into solvent. The released TMD then penetrates into the membrane. We suggest that the disulfide bond regulates the membrane binding mode of PrP by controlling the motional freedom of the TMD.

• Nutrition Research and Practice
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• v.14 no.2
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• pp.95-101
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• 2020

BACKGROUND/OBJECTIVES: Folate plays a critical role in DNA synthesis and methylation. Intracellular folate homeostasis is maintained by the enzymes folylpolyglutamate synthase (FPGS) and γ-glutamyl hydrolase (GGH). FPGS adds glutamate residues to folate upon its entry into the cell through a process known as polyglutamylation to enhance folate retention in the cell and to maintain a steady supply of utilizable folate derivatives for folate-dependent enzyme reactions. Thereafter, GGH catalyzes the hydrolysis of polyglutamylated folate into monoglutamylated folate, which can subsequently be exported from the cell. The objective of this review is to summarize the scientific evidence available on the effects of intracellular folate homeostasis-associated enzymes on cancer chemotherapy. METHODS: This review discusses the effects of FPGS and GGH on chemosensitivity to cancer chemotherapeutic agents such as antifolates, such as methotrexate, and 5-fluorouracil. RESULTS AND DISCUSSION: Polyglutamylated (anti)folates are better substrates for intracellular folate-dependent enzymes and retained for longer within cells. In addition to polyglutamylation of (anti)folates, FPGS and GGH modulate intracellular folate concentrations, which are an important determinant of chemosensitivity of cancer cells toward chemotherapeutic agents. Therefore, FPGS and GGH affect chemosensitivity to antifolates and 5-fluorouracil by altering intracellular retention status of antifolates and folate cofactors such as 5,10-methylenetetrahydrofolate, subsequently influencing the cytotoxic effects of 5-fluorouracil, respectively. Generally, high FPGS and/or low GGH activity is associated with increased chemosensitivity of cancer cells to methotrexate and 5-fluorouracil, while low FPGS and/or high GGH activity seems to correspond to resistance to these drugs. Further preclinical and clinical studies elucidating the pharmocogenetic ramifications of these enzyme-induced changes are warranted to provide a framework for developing rational, effective, safe, and customized chemotherapeutic practices.

• Structural Engineering and Mechanics
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• v.32 no.4
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• pp.477-488
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• 2009

A slip critical joint has various values to adopt the proper slip coefficient in various conditions of faying surfaces in the following codes: AISC, AIJ and Eurocode 3. However, the Korean Building Code still regulates the unique slip coefficient, 0.45, regardless of the diverse faying conditions. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The faying surfaces were comprised of a clean mill, rust, red lead paint, zinc primer, and shot blast treatment. The candidates for high strength bolts were torque-shear bolts, torque-shear bolts with zinc coating, and ASTM A490 bolts. Based on the test results, the specimens with a shot blasted surface and rusted surface exhibited $k_s$, 0.61, and 0.5, respectively. It is recommended that the specimens with zinc primer exhibit $k_s{\geq}0.40$. The clean mill treated surface had prominently lower values, 0.27. For red lead painted treatment, the thickness of the coating affects the determinant of slip coefficient, so it is necessary to establish a minimum $k_s$ of 0.2, with a coating thickness of 65 ${\mu}m$. During 1,000 hours of relaxation, the uncoated surfaces exhibited the loss of clamping force behind 3%, while the coated surfaces within a certain limited thickness exhibited the loss of clamping within a range of 4.71% and 8.37%.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.784-789
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• 2016

We evaluated the synergistic antibacterial effect in combination with the chitosan-ferulic acid conjugate (CFA) and β-lactam antibiotics, such as ampicillin, penicillin, and oxacillin, against methicillin-resistant Staphylococcus aureus (MRSA) using fractional inhibitory concentration (FIC) indices. CFA clearly reversed the antibacterial activity of ampicillin, penicillin, and oxacillin against MRSA in the combination mode. Among these antibiotics, the combination of oxacillin-CFA resulted in a ΣFIC_min range of 0.250 and ΣFIC_max of 0.563, suggesting that the oxacillin-CFA combination resulted in an antibacterial synergy effect against MRSA. In addition, we determined that CFA inhibited the mRNA expression of gene mecA and the production of PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. Thus, the results obtained in this study supported the idea on the antibacterial action mechanism that oxacillin will restore the antibacterial activity against MRSA through the suppression of PBP2a production by CFA.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.4
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• pp.323-330
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• 2004

Estrogen may promote osteoblast/osteocyte viability by limiting apoptotic cell death. We hypothesize that hsp27 is an estrogen- regulated protein that can promote osteoblast viability by increasing osteoblast resistance to apoptosis. The purpose of this study was to determine the effect of estrogen treatment and heat shock on $TNF{\alpha}$ - induced apoptosis in the MC3T3-E1 cell line. Cells were treated with 0 - 100 nM $17{\beta}$ estradiol (or ICI 182780) for 0 - 24 hours before heat shock. After recovery, apoptosis was induced by treatment with 0 - 10 ng/ml TNF${\alpha}$. Hsp levels were evaluated by Northern and Western analysis using hsp27, hsp47, hsp70c and hsp70i - specific reagents. Apoptosis was revealed by in situ labeling with Terminal Deoxyribonucleotide Transferase (TUNEL). A 5 - fold increase in hsp27 protein and mRNA was noted after 5 hours of treatment with 10 - 20 nM $17{\beta}$ estradiol prior to heat shock. Increased abundance of hsp47, hsp70c or hsp70i was not observed. TUNEL indicated that estrogen treatment also reduced (50%) MC3T3-E1 cell susceptibility to $TNF{\alpha}$ - induced apoptosis. Treatment with hsp27-specific antisense oligonucleotides prevented hsp27 protein expression and abolished the protective effects of heat shock and estrogen treatment on $TNF{\alpha}$- induced apoptosis. Hsp27 is a determinant of osteoblast apoptosis, and estrogen treatment increases hsp27 levels in cultured osteoblastic cells. Hsp27 contributes to the control of osteoblast apoptosis and may be manipulated by estrogenic or alternative pathways for the improvement of bone mass.

• Journal of Animal Science and Technology
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• v.48 no.2
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• pp.169-190
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• 2006

Researches in livestock are currently actively progressing to improve economically important traits using DNA markers. In cattle, the candidate genes have been selected based on their known functions in the target QTL (quantitative trait locus) region in order to identify QTN (quantitative trait nucleotide) for improving productivities. In this review, molecular genetic studies for the meat related traits, one of the major determinant of market prices, have been fully described. Also recent emerging microarray technique for identifying candidate genes in cattle has been discussed. In case of microarray, cDNA microarrays have been replaced to oligoarrays in order to minimize the experimental errors in cattle. Since the first draft of bovine genome sequences was appeared in the public domain, more markers in relation to the quantitative traits will be discovered in a short period of time and genes affecting difficult-to-measure traits, such as disease resistance, can also be selected for marker assisted selection in near future.

• Tuberculosis and Respiratory Diseases
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• v.42 no.5
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• pp.777-780
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• 1995

Salmonellosis is one of communicable disease and still occur in sporadic in Korea frequently. They are four main clinical manifestations in salmonellosis. They are gastrocnteritis, typhoidal or septisemia syndrome, focal manifestation and carrier state. Among them, focal manifestation is rarely seen. Saphra, et al. reported that localized salmonella infection is about 5%. Localized salmonella infection frequently occur during salmonella bacteremia, but may also occur with enteric fever or gastroenteritis. Gray, et al reported 3390 cases of minor gunshot wound infection that bacterial isolates from infected wounds consisted of Staphylococcus aureus(90%), Streptococcus sp.(6%), and mixed organisms(4%). Incresed host susceptibility to infection secondary to lowered resistance due to debilitating disease is an important determinant of Salmonella infection. Since salmonella is seldom suspected as a cause of soft tissue infections, there is usually a dangerous delay in the institution of appropriate antimicrobial therapy and isolation procedure. We experienced one case of subcutaneous salmonella abscess developed on gunshot wound area in lung cancer patient, which was confirmed by pus culture.