• Toxicological Research
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• v.12 no.1
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• pp.9-15
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• 1996

We studied the effects of a single, combined and mixed exposure of benzene, toluene and xylene on the activities of rat liver microsomal AHH, ADH and ALDH, and the excretion of their metabolites in urine. The AHH activities of the rats treated in combination and mixture were slightly higher and/or similar to those rats treated with single solvent, while the reverse effects were observed for ADH and ALDH. Similar effects were observed when the metabolites were examined in urine (p < 0.01). These results suggest that each solvent might interJkre the induction and action of ADH and ALDH, and decrease the excretion of their metabolites into urine.

• Molecules and Cells
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• v.42 no.4
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• pp.313-320
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• 2019

Intraepithelial lymphocytes (IELs) develop through the continuous interaction with intestinal antigens such as commensal microbiome and diet. However, their respective roles and mutual interactions in the development of IELs are largely unknown. Here, we showed that dietary antigens regulate the development of the majority of $CD8{\alpha}{\beta}$ IELs in the small intestine and the absence of commensal microbiota particularly during the weaning period, delay the development of IELs. When we tested specific dietary components, such as wheat or combined corn, soybean and yeast, they were dependent on commensal bacteria for the timely development of diet-induced $CD8{\alpha}{\beta}$ IELs. In addition, supplementation of intestinal antigens later in life was inefficient for the full induction of $CD8{\alpha}{\beta}$ IELs. Overall, our findings suggest that early exposure to commensal bacteria is important for the proper development of dietary antigen-dependent immune repertoire in the gut.

• Development and Reproduction
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• v.16 no.4
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• pp.295-300
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• 2012

Manganese ($Mn^{2+}$) is a trace element that is essential for normal physiology, and is predominantly obtained from food. Several lines of evidence, however, demonstrated that overexposure to $MnCl_2$ exerts serious neurotoxicity, immunotoxicity and developmental toxicity, particularly in male. The present study aimed to evaluate the effect of 0, 1.0, 3.3, and 10 mg/kg/day doses of $MnCl_2$ on the reproductive organs in the immature female rats. Rats (PND 22; S.D. strain) were exposed to $MnCl_2$ ($MnCl_2{\cdot}4H_2O$) dissolved in drinking water for 2 weeks. The animals were sacrificed on PND 35, then the tissues were immediately removed and weighed. Histological studies were performed using the uteri tissue samples. Serum LH and FSH levels were measured with the specific ELISA kits. Body weights of the experimental group animals were not significantly different from those of control group animals. However, ovarian tissue weights in 1 mg and 3.3 mg $MnCl_2$ dose groups were significantly lower than those of control animals (p<0.05 and p<0.01, respectively). Uterine tissue weights of 3.3 mg dose $MnCl_2$ groups were significantly lower than those of control animals (p<0.01), while the 1 mg $MnCl_2$ dose and 10 mg $MnCl_2$ dose failed to induce any change in uterine weight. Similarly, only 3.3 mg $MnCl_2$ dose could induce the significant decrease in the oviduct weight compared to the control group (p<0.05). Non-reproductive tissues such as adrenal and kidney failed to respond to all doses of $MnCl_2$ exposure. The uterine histology revealed that the $MnCl_2$ exposure could affect the myometrial cell proliferation particularly in 3.3 mg dose and 10mg dose group. Serum FSH levels were significantly decreased in 1mg $MnCl_2$ dose and 10 $MnCl_2$ mg groups (p<0.05 and p<0.01, respectively). In contrast, treatment with 1 mg $MnCl_2$ dose induced a significant increment of serum LH level (p<0.05). The present study demonstrated that $MnCl_2$ exposure is capable of inducing abnormal development of reproductive tissues, at least to some extent, and altered gonadotropin secretions in immature female rats. Combined with the well-defined actions of this metal on GnRH and prolactin secretion, one can suggest the $Mn^{2+}$ might be a potential environmental mediator which is involved in the female pubertal process.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.5
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• pp.425-437
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• 2001

This study is based on the uses meta-analysis methodology to examine the statistical consistency and importance of random variation among results of epidemiologic studies between air pollutants exposure and childhood asthma. Studies for this meta-analysis were conducted by reviewing previous results and by asking researcher active in this field for recommendations. Overall, 10 cases of air pollutants exposures and childhood asthma were reviewed. A variety of statistical methods for meta-analysis have been used to assess the combined effects, to identify heterogeneity, and to provide a single summary risk estimate based on a set of simiar epidemiologic studies. In this study, classification of exposure metircs on air environmental epidemiologic studies are reported for (1) aggravation of childhood asthma by a 50 ppb increase SO$_2$(6 individual studies); (2) aggravation of childhood asthma by a 50 ppb increase NO$_2$(5 individual studies); (3) aggravation of childhood asthma by a 50 ppb increase $O_3$(7 individual studies); (4) aggravation of childhood asthma by a 10$\mu\textrm{g}$/m$^3$increase PM$_{10}$ (4 individual studies); (5) aggravation of childhood asthma by a 1 ppm increase CO (2 individual studies); and (6) comparison of results between a Korean study results and this meta-analytic study. Results of this study indicated that an inverse-variance weighted pooling of the hospital admission risk at a 1ppm increment of CO levels was 1.12% (95% CI : 1.01 ~ 1.24). The hospital admission risk was estimated to increase 5% (95% CI : 1.02~1.08), 6%(95% CI : 1.04~1.09), and 5% (95% CI : 1.02~1.09) with each 50ppb increase of SO$_2$, NO$_2$, and $O_3$, respectively. In addition, our results lead to a small but significant elevation in risk of 2% (RR = 1.02, 95% CI = 1.01~1.04) with each 10$\mu\textrm{g}$/m$^3$increase of PM$_{10}$ among 4 individual studies. We found a small elevation in risk of childhood asthma, and pooled results of 10 epidemiologic studies of childhood asthma using increase a cut-off-point levels of air pollutants showed a few pieces of evidence. The results of this meta-analysis suggested that air pollution associated with an increased incidence of childhood asthma. According to this study, relationship between exposure to air pollutants and childhood asthma in Korea seem to be high than results of this meta-analysis.sis.

• Journal of fish pathology
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• v.27 no.1
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• pp.57-65
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• 2014

Copper ($CuSO_4$) has been widely used to control algae and pathogens in fish culture ponds. However, its toxic effects on fish depend not only on its concentration in water but also on water quality. The susceptibility of the rockfish, Sebastes schlegeli to copper was evaluated at three water-temperatures (WT; 18, 23 and $28^{\circ}C$) for 4 days. After the exposure of two copper concentrations (100 and $200{\mu}g/L$), a hematological effect was exerted on rockfish, by causing changes in red blood cell count and hematocrit value at $28^{\circ}C$. Total protein levels of the fish showed a tendency of co-increase with glucose depend on the WT, after copper exposure. However, the plasma calcium and magnesium levels were significantly increased at $200{\mu}g/L$ copper, regardless of the WT. Enzymes activities including ALT and LDH in serum were also significantly increased depend upon the copper treatment only. This indicates that inorganic components and enzymes activities were sensitive indexes to stress by toxicant such as copper. The cortisol levels were significantly elevated by both WT rising and copper treatment in serum of rock fish. In conclusion, these changes can be seen as an initial response to temperature stress and as a sustaining response to copper exposure. The present findings suggest that a simultaneous stress by temperature change and copper exposure could accelerate an alteration of hematological and plasma biological parameters in the rockfish.

• Journal of Preventive Medicine and Public Health
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• v.35 no.1
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• pp.49-56
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• 2002

Objectives : To identify the relationship between the use of medical services by workers with three types of respiratory diseases(total respiratory diseases, acute upper respiratory infections and chronic lower respiratory diseases) and exposure to hazardous agents after controlling for other factors affecting medical services use, such as characteristics of the enterprises(scale, industry type) and employee demographics (sex, age). Methods : The study population comprised 28,882 workers who had undergone general or special medical examinations at the industrial health center at least once between Jan 1995 and Dec 1997 and had possessed medical insurance during the period. We combined medical examination data with medical insurance data in order to analyze the relationship between exposure to hazardous agents and respiratory diseases, Results : Among the 28,882 study subjects, 17,454 employees(60.4%) used medical services more than once during 3-year study period, owing to more than one kind of respiratory diseases. In logistic regression analysis, sex, age and the size of the enterprises proved to be significant variables on the use of medical services for all three types of respiratory disease; The use of medical services increased with employee age. Women used more medical services than men and the employees in the large-scale enterprises used more services than employees in small-scale enterprises. However, exposure to dust or organic solvents did not affect medical service use due to total respiratory diseases or acute upper respiratory infections. Only in the case of chronic lower respiratory diseases did workers exposed to dusts(OR=1.12, 95% CI=1.01-1.24) or organic solvents(OR=1.19, 95% CI=1.05-1.35) use more medical services than those not exposed. Conclusions : Workers exposed to dusts or organic solvents are particularly apt to suffer from chronic lower respiratory diseases and use medical services more often than those not exposed. That is, chronic exposure to hazardous agents such as dusts and organic solvents is believed to be harmful and to cause respiratory symptoms and diseases.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.248-254
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• 2018

To assess the risk of V. parahaemolyticus infection caused by consumption of raw oysters in Korea, contamination levels during the retail-to-table route of oysters was modeled to predict V. parahaemolyticus growth based on temperature and time. The consumed amount data of the KNHANES and the standard recipe of RDA were applied. A consumption scenario for exposure assessment was developed and combined with a Beta-Poisson dose-response model. The estimated probability of illness from consumption of pathogenic V. parahaemolyticus in raw oysters during three separate months (April, October, and November) was $5.71{\times}10^{-5}$ (within the 5th and 95th percentile ranges of $2.71{\times}10^{-8}$ to $1.03{\times}10^{-4}$). The results of the quantitative microbial-risk assessment indicated that the major factors affecting the probability of illness were the initial contamination level at the retailer, the consumed amount, the prevalence of pathogenic strains [tdh or trh genes], and exposure temperature and time.

• Journal of Broadcast Engineering
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• v.22 no.6
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• pp.702-712
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• 2017

In this paper, we propose an unsharp masking algorithm using Laplacian as a weight map for the signal structure and a gamma transformation algorithm using image mean intensity as a weight map for mean intensity. The conventional weight map based on the patch has a disadvantage in that the brightness in the image is shifted to one side in the signal structure and the mean intensity region. So the detailed information is lost. In this paper, we improved the detail using unsharp masking of patch unit and proposed linearly combined the gamma transformed values using the average brightness values of the global and local images. Through the proposed algorithm, the detail information such as edges are preserved and the subjective image quality is improved by adjusting the brightness of the light. Experiment results show that the proposed algorithm show better performance than conventional algorithm.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.507-512
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• 2004

This study was focused on the risk assessment of whether radiofrequency electromagnetic fields generated by mobile phone is cytogenetically toxic or not. We conducted the effects of 835-MHz electromagnetic field (EMF) on DNA strand breaks in mouse thymic lymphoma L5178Y $Tk^{+/1-}$ cells using alkaline comet assay. EMF frequency 835-MHz we chosen is one of the most popular communication frequency bands in Korean code-division multiple-access (CDMA) mobile phone system. The cells were exposed to 835-MHz EMF alone or 835-MHz EMF combined with cyclophosamide(CPA) or 4-nitroquinoline-1-oxide (4NQO) at specific absorption rate (SAR) of 4.0 W $kg^{-l}$ for 24 and 48hrs. DNA damage expressed as tail moment was increased more than two-fold after exposure to 835-MHz EMF for 24 and 48hr. In particular, CPA for 48hr and 4NQO for 24 hr enhanced notably the tail moment to 9-fold and 16-fold in the presence of 835-MHz EMF, respectively, compared to each single treatment. From these results, it appears that exposure to CDMA-mobile phone radiation at 835-MHz frequency may potentiate DNA strand breaks of mouse thymic lymphoma L5178Y $Tk^{+/1-}$;cells under the defined conditions of this study.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.147-154
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• 2020

In this study, four types of composite added filtration (aluminum, nickel, copper, and zinc) were combined for each thickness to evaluate dose reduction and optimal images due to X-ray attenuation. To evaluate dose and image quality. X-ray generators, Dose Area Product(DAP) and ICY programs with RQR9 standard quality were used. In the image quality evaluation element (PSNR, RMSE, SSIM), only images with PSNR value of 30 dB or more were analyzed. As a result, the best combination in dose evaluation was 3 mmAl + 0.6 mmNi (0.16µGy㎡), and the best filter in image quality evaluation was 0.9 mmAl (PSNR 34.24dB, RMSE 79.52, SSIM 0.24). In this study, the dose aspect and the image quality aspect are mentioned, So it is considered that further studies on patient's exposure dose and optimal image will be needed in the future.