• The Korean Journal of Applied Statistics
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• v.26 no.3
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• pp.453-470
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• 2013

In this paper, we consider a Bayesian analysis of the dose-effect relationship of cadmium to evaluate a benchmark dose(BMD). For this purpose, two dose-response curves commonly used in the toxicity study are fitted based on Bayesian methods to the data collected from the scientific literature on cadmium toxicity. Specifically, Bayesian meta-analysis and hierarchical modeling build an overall dose-effect relationship that use a piecewise linear model and Hill model, where the inter-study heterogeneity and inter-individual variability of dose and effect such as gender, age and ethnicity are accounted. Estimation of the unknown parameters is made by using a Markov chain Monte Carlo algorithm based user-friendly software WinBUGS. Benchmark dose estimates are evaluated for various cut-offs and compared with different tested subpopulations with with gender, age and ethnicity based on these two Bayesian hierarchical models.

• Biomedical Science Letters
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• v.12 no.3
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• pp.289-301
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• 2006

Cardiopulmonary bypass (CPB) for cardiac surgery triggers the production and release of numerous chemotactic substances and cytokines, ensuing systemic inflammatory response that leads to postoperative major organ dysfunction. Traditionally, corticosteroids (steroid) have been administered to patients undergoing cardiac surgery to ward off these detrimental physiologic alterations. However, the majority of the studies have been performed on adult patients with high-dose steroid. We carried out a randomized, prospective, double-blind study to compare the efficacy of low-dose steroid with that of high-dose steroid and to determine the adequate dose of pretreated-steroid for prophylactic effects in pediatric cardiac surgery. Thirty pediatric patients scheduled for elective cardiac surgery were randomly assigned to two groups; fifteen patients received low-dose methylprednisolone (10mg/kg intravenously, n=15, low-dose group) and the others received high-dose methylprednisolone (30mg/kg intravenously, n=15, high-dose group) 1 hour prior to CPB. Arterial blood samples were taken before CPB (Pre-CPB), 10 minutes after start of CPB (CPB-10), and immediately after CPB-end (CPB-OFF) for measuring total leukocyte counts (T-WBC) and diff-counts, platelet counts, interleukin-6 (IL-6), myeloperoxidase (MPO), total antioxidant (TAO), neuron-specific enolase (NSE), troponin I (TNI), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine, and blood urea nitrogen (BUN) levels. Other parameters such as volumes of urine output, pulmonary index $(PI,\;PaO_2/FiO_2)$, mechanical ventilating period, intensive care unit (ICU)-staying period, postoperative complications (fever, wound problem), postoperative 24 hrs and total volumes in blood loss, and hospitalized days were also assessed. All parameters were compared between two groups. There were no significant differences in T-WBC counts, monocyte fraction, platelet counts, TA levels, NSE levels, creatinine levels, BUN levels, the volumes of total urine output, PI, the incidences of fever and wound problem, postoperative 24hrs- and total-blood loss volumes and ICU-staying period between two groups (P>0.05). At CPB-OFF, neutrophil fraction, MPO level, TNI level, and AST level were higher in the high-dose group than in the low-dose group (P<0.05). IL-6 level at CPB-10 was higher in the high dose-group than in the low-dose group (P<0.05). Furthermore, mechanical ventilating periods and hospitalized days of the high-dose group were significantly longer than those of low-dose group (P<0.05). The high-dose group had significantly low lymphocyte fi-action at CPB-OFF compared with the low-dose group (P<0.001). These findings suggest that pretreatment of high-dose steroid is not superior to that of low-dose steroid regrading its potential benefits in pediatric cardiac surgery. Therefore, the conventional strategy of steroid treatment, high-dose pretreatment, should be modified in the cardiac surgery with CPB. However, further studies must be performed on the larger number of patients in as much as small number of patients in this study.

• Animal cells and systems
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• v.5 no.1
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• pp.77-83
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• 2001

The present study was conducted to elucidate whether the expression level of poly(ADP-ribose) polymerase (PARP) is related to the ultraviolet radiation (UV)-induced apoptosis. After treatment of the mammalian cell lines HeLa S3 and Chinese hamster ovary (CHO) with 50 J/m2 UV, induction of apoptosis was determined by several means during 24 h post-incubation. Incidence of apoptosis was much lower in CHO than HeLa S3 cells based on the percentage of apoptotic cells in terms of morphological changes in nucleus or direct counting of viable cells and qualitative or quantitative DNA fragmentation. Interestingly, when the expression level of PARP was measured by western blotting, the amounts of PARP that was retained at each time point inversely correlated with the incidences of apoptosis in these cells. Concomitant with generation of the 85 kDa fragment, 116 kDa PARP disappeared in HeLa S3 within 6 h after UV treatment, whereas a fair amounts of 116 kDa band was still retained in CHO cells at 36 h post-incubation. This inverse relationship was also observed in the adaptive response system, in which cells weve treated with a high dose of UV after pretreatment with a low dose. As expected, typical adaptive responses appeared in CHO cells but not in HeLa cells, showing greater cell viability and lesser DNA fragmentation. During the adaptive response in CHO cells, PARP was expressed at much higher level compared to the single, high dose-treated cells. Interestingly, even though PARP was induced at 6 h post-incubation In both cell types, its expression was more prominent in CHO cells. Thus, our data indicate that the retained level of intact PARP against UV damage inversely correlates with incidence of apoptosis in mammalian cells, and also suggest that a machinery to protect the PARP degradation against UV damage exists in CHO but not in HeLa S3 cells.

• The Journal of Korean Society for School & Community Health Education
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• v.18 no.1
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• pp.1-12
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• 2017

Objectives: This study aimed to analyze sexual experience rates according to socio-demographic factors, health behavioral factors, and internet use time, and to identify sex experience related factors in high school students using the data from the 11th Korean Youth Health Risk Behavior Web-Based Survey. Methods: A total of 33,744 students (17,346 boys and 16,398 girls) in high schools were analyzed using the SPSS WIN version 22 program. SPSS complex samples methods were used for analyses. Socio-demographic factors, health behavioral factors, and internet use time as independents variables were included. The complex samples logistic regression analyses were used to calculate the odds ratio of the sexual experience according to the socio-demographic factors, health behavioral factors and internet use time. Unweighted frequencies and percentages were represented in result tables. Results: 3.6% of girls and 9.9% of boys in high school had sexual experiences. Daily average smoking amount and daily alcohol drinking amount were a dose-response relationship with sexual experience after considering confounding factors. Students who smoke 10-19 cigarettes had 5.74 times higher risk and 20 cigarettes or more had 7.27 times higher risk of sexual experiences, comparing with non-smoking students, relatively. Likewise, students who drink soju less than 1-2 bottles and more than 2 bottles had 3.82- and 4.35 times higher chance of sexual experiences, compared with non drinking students, respectively. Conclusions: We found that there were the dose-response relationship between health behavioral characteristics and sexual experiences. Further research is needed to identify an interaction effect between smoking and drinking alcohol on sexual experiences in high school students.

• Environmental Engineering Research
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• v.20 no.3
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• pp.223-229
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• 2015

The application of coagulation for feed water pretreatment prior to microfiltration (MF) process has been widely adopted to alleviate fouling due to particles and organic matters in feed water. However, the efficiency of coagulation pretreatment for MF is sensitive to its operation conditions such as pH and coagulant dose. Moreover, the optimum coagulation condition for MF process is different from that for rapid sand filtration in conventional drinking water treatment. In this study, the use of response surface methodology (RSM) was attempted to determine coagulation conditions optimized for pretreatment of MF. The center-united experimental design was used to quantify the effects of coagulant dose and pH on the control of fouling control as well as the removal organic matters. A MF membrane (SDI Samsung, Korea) made of polyvinylidene fluoride (PVDF) was used for the filtration experiments. Poly aluminum chloride (PAC) was used as the coagulant and a series of jar tests were conducted under various conditions. The flux was $90L/m^2-h$ and the fouling rate were calculated in each condition. As a result of this study, an empirical model was derived to explore the optimized conditions for coagulant dose and pH for minimization of the fouling rate. This model also allowed the prediction of the efficiency of the coagulation efficiency. The experimental results were in good agreement with the predictions, suggesting that RSM has potential as a practical method for modeling the coagulation pretreatment for MF.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2459-2465
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• 2012

Background: Numbers of epidemiological studies assessing residential radon exposure and risk of lung cancer have yielded inconsistent results. Methods: We therefore performed a meta-analysis of relevant published case-control studies searched in the PubMed database through July 2011 to examine the association. The combined odds ratio (OR) were calculated using fixed- or random-effects models. Subgroup and dose-response analyses were also performed. Results: We identified 22 case-control studies of residential radon and lung cancer risk involving 13,380 cases and 21,102 controls. The combined OR of lung cancer for the highest with the lowest exposure was 1.29 (95% CI 1.10-1.51). Dose-response analysis showed that every 100 Bq/$m^3$ increment in residential radon exposure was associated with a significant 7% increase in lung cancer risk. Subgroup analysis displayed a more pronounced association in the studies conducted in Europe. Studies restricted to female or non-smokers demonstrated weakened associations between exposure and lung cancer. Conclusions: This meta-analysis provides new evidence supporting the conclusion that residential exposure to radon can significantly increase the risk of lung cancer in a dose-response manner.

• Journal of Environmental Health Sciences
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• v.38 no.1
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• pp.73-81
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• 2012

Objectives: With the goal of quantifying the risk of children contracting gastroenteritis while playing at interactive waterscape facilities and evaluating the adequacy of current water quality regulations, risk assessment was performed with Escherichia coli as pathogen. Methods: Abundances of E. coli in the waters of interactive water features in South Korea were acquired from survey reports. A gamma distribution describing the volume of water swallowed by children during swimming activities was adopted. Exposure rate and risk were calculated by Monte Carlo simulation and dose-response models for various pathogenic E. coli. Results: E. coli was detected in 25 out of 40 facilities, with range of ~1,600 CFU/100 ml. The abundance fitted an exponential distribution. Simulated exposures ranged ${\sim}1.9{\times}10^{10}$ CFU, varying greater along E. coli abundance than the volume of water. Risk of children being infected by enterohemorrhagic E. coli was high, with range of ~0.85. When E. coli abundance was <200 CFU/100 ml, which is the current government threshold, the risk decreased to <0.43. Although the guideline successfully reduced the risk of adults being infected by a less virulent E. coli strains (<0.03), the risk for children could not be quantified due to lack of dose-response models for those pathogens for children. Conclusions: Under the current guideline, children are at risk of being infected if water is contaminated with by enterohemorrhagic E. coli. For other E. coli strains, the risk appears to be considerably less. The result warrants need for developing dose-response models for children for each pathogenic E. coli strain.

• The Korean Journal of Community Living Science
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• v.15 no.2
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• pp.167-177
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• 2004

The number of foodborne salmonellosis was estimated by using microbial risk assessment(MRA) methodology and the possibility of application was studied through comparison with previous results. The contamination levels of Salmonella sp. were estimated by using published domestic studies(1997∼2000) and monitoring data (1999∼2001) from food-safety related institutes. Data on food consumption came from the 2001 National Health and Nutrition Survey, and dose-response models from studies in other countries. Simulation results showed that there were 753,368 cases of salmonellosis in Korea in 1 year, which is about 115 times that reported in previous years and lower than the WHO's estimation increase. From these results, microbial risk assessment is likely to be available for estimation of the number of foodborne illnesses and determination of the order of priority in food-safety management. Butthe verification methods are not established and most of the data on contamination levels of foodborne bacteria, food consumption, and dose-response relationships have not been established. In addition, the actual conditions of circulation, storage and cooking must be studied further.

• Environmental Engineering Research
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• v.14 no.2
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• pp.81-87
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• 2009

The decomposition of antibiotics (cefaclor) by gamma irradiation in aqueous solutions was experimentally evaluated. To obtain a mutual interaction between two factors (antibiotics concentrations and radiation doses) and to optimize these factors during the process, experimental design and statistical analysis were employed. The decomposition capability of the gamma radiation was also mathematically described as a function of cefaclor concentration and gamma-ray dose using the statistical analysis. The results showed that the cefaclor concentration ($X_1$) in the response $Y_1$ (Reduction of cefaclor concentration) and gamma-ray dose ($X_2$) in the response $Y_2$ (Removal efficiency (%) of cefaclor concentration) exhibited a significantly positive effect, whereas gamma-ray dose ($X_2$) in the response $Y_1$ showed a significantly negative effect. The estimated ridge of maximum responses and optimal conditions for $Y_1$:($X_1$,$X_2$)=(25 mg/L, 350 Gy) and $Y_2$:($X_1$,$X_2$)=(21 mg/L, 565 Gy) using canonical analysis were 4.37 mg/L of reduction of cefaclor concentration and 98.35% of removal efficiency of cefaclor concentration, respectively. The measurement values agreed well with the predicted ones, thereby confirming the suitability of the model for $Y_1$ and $Y_2$ and the success of the experimental design in optimizing the conditions of the gamma irradiation process.

• Journal of Food Hygiene and Safety
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• v.24 no.1
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• pp.50-55
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• 2009

Ready-to-eats fresh cut-vegetables that may be consumed without further cooking or reheating can be grouped as potentially high risk foods. The foodborne disease outbreaks associated with consumption of the fresh cut-vegetables have been related with the contamination of Listeria monocytogenes. The food survey and consumption data sets for fresh cut-vegetables and also the published dose-response models for L. monocytogenes, was used to estimate the risk of L. monocytogenes for fresh cut-vegetables in Korea. Also, the simulation model and formulas with Microsoft@ Excel spreadsheet program using these data sets and chose dose-response model was developed. The mean case of listeriosis by consumption of the fresh cut-vegetables per 10 million per year was estimated as $3.23{\times}10^{-6}$. Results suggest that additional studies were needed to allow for a more realistic and accurate microbial risk assessment (MRA) in the future.