• Toxicological Research
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• v.34 no.4
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• pp.281-290
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• 2018

Exposure to chemical agents is an inevitable consequence of modern society; some of these agents are hazardous to human health. The effects of chemical carcinogens are of great concern in many countries, and international organizations, such as the World Health Organization, have established guidelines for the regulation of these chemicals. Carcinogens are currently categorized into two classes, genotoxic and non-genotoxic carcinogens, which are subject to different regulatory policies. Genotoxic carcinogens are chemicals that exert carcinogenicity via the induction of mutations. Owing to their DNA interaction properties, there is thought to be no safe exposure threshold or dose. Genotoxic carcinogens are regulated under the assumption that they pose a cancer risk for humans, even at very low doses. In contrast, non-genotoxic carcinogens, which induce cancer through mechanisms other than mutations, such as hormonal effects, cytotoxicity, cell proliferation, or epigenetic changes, are thought to have a safe exposure threshold or dose; thus, their use in society is permitted unless the exposure or intake level would exceed the threshold. Genotoxicity assays are an important method to distinguish the two classes of carcinogens. However, some carcinogens have negative results in in vitro bacterial mutation assays, but yield positive results in the in vivo transgenic rodent gene mutation assay. Non-DNA damage, such as spindle poison or topoisomerase inhibition, often leads to positive results in cytogenetic genotoxicity assays such as the chromosome aberration assay or the micronucleus assay. Therefore, mechanistic considerations of tumor induction, based on the results of the genotoxicity assays, are necessary to distinguish genotoxic and non-genotoxic carcinogens. In this review, the concept of threshold of toxicological concern is introduced and the potential risk from multiple exposures to low doses of genotoxic carcinogens is also discussed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.1
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• pp.49-54
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• 2011

In order to develop the methods for exposure assessment and find susceptibility markers for the workers who are exposed to low doses of toluene, xylene and other chemical in petroleum industries, we investigated the application of P-450 expression in human lymphocytes utilizing mouse monoclonal anti-rat CYP2B1/2, the levels of toluene and xylene in air and their metabolite levels in urine with the levels of expressed CYP2B1/2 proteins. The general characteristics such as age, smoking and drinking habit were no significant difference between the control and exposed workers, but the working durations and working hours were significantly different. Workers in exposed group were exposed to the mean of 2.1 ppm (range, 0.00-4.54) of toluene and 0.3 ppm (rang, 0.00-1.23) of xylene. The mean concentration of urinary hippuric acid was low and less than 1/5 of the biological exposure index recommended by the Ministry of Employment and Labor Korea. Methyl hippuric acid in urine was not detected in control and exposed workers. Also, there were no significant differences in the levels of the urinary metabolites between the control and exposed group. When chemiluminescence dot blottings were carried out utilizing mouse monoclonal antibody against CYP2B1/2, the strong density dots corresponding to a mouse monoclonal antibody was observed in the human lymphocytes from the exposed workers. These results suggested that the chemiluminescence dot blot assay for CYP of lymphocytes should be valuable for identifying CYP expression as biomarkers in the workers exposed to toluene and xylene.

• The Journal of Internal Korean Medicine
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• v.30 no.2
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• pp.338-354
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• 2009

Objective : Gamijihwang-tang(GJT) has been used as a therapeutic agent for hyperlipidemia in oriental medicine for several years. This study was performed to investigate the effects of GJT on hyperlipidemia in rats using diverse biological methods. Method : Hyperlipidemia was induced by a hyper-lipidemic diet fed for 4 weeks. Total cholesterol, LDL-cholesterol, HDL-cholesterol, triglyceride, and glucose were measured in the serum after an oral administration of GJT. Lipid peroxidase, SOD, catalase, ACAT, and HMG-CoA were measured in liver after oral administration of GJT. Result: 1. GJT showed safety against cytotoxicity and toxicity in liver. 2. GJT significantly decreased rat's body and liver weight. 3. GJT significantly decreased serum total cholesterol and LDL-cholesterol, but increased serum HDL-cholesterol. 4. GJT significantly decreased serum triglyceride and glucose. 5. GJT significantly decreased lipid peroxidation and increased SOD and catalase in liver. 6. GJT significantly decreased ACAT and HMG-CoA reductase of cholesterol manifestation in liver. Conclusions : These results suggest that GJT might be effective in treatment and prevention of hyperlipidemia.

• Korean Journal of Weed Science
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• v.31 no.2
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• pp.212-219
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• 2011

The water dispersible granule flupoxam showed over 95% of weeding effect on the annual weeds of Poaceae such as Poa annua L., Digitaria ciliaris (Rets.) Koel and broad-leaf weeds. Efficacy of treatment had been lasted over 120 days in the $2kg\;ha^{-1}$ when it was treated from March to April while lasted over 180 days when it was treated from September to October. Because the flupoxam has a high soil absorptivity, a perfected herbicide layer is formed. This results in perfect weeding effect regardless of the presence or absence of thatch. Because the flupoxam has a different mechanism of action from the conventional herbicides such as dinitroanilines, pyridines, and carbamates, it is very effective with the alternative spray. Phytotoxicity symptoms was not observed and/or produced antocyan in new leaves in the landscape trees around the lawngrass by flupoxam treatment.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.30-37
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• 2011

This ultra real-time PCR (UPCR) based diagnosis system for avian influenza A virus (AIV) subtype was designed. The target primer in this study was derived from H5N1 subtype-specific 133 bp partial gene of hemagglutinin (HA), and was synthesized by using PCR-based gene synthesis on the ground of safety. UPCR was operated by Mini-Opticon Q-PCR Quantitative Thermal Cycler using aptamer-based molecular beacon, total 10 ${\mu}l$ of reaction mixture with extraordinarily short time in each steps in PCR. The detection including UPCR and analysis of melting temperature was totally operated within 15 min. The AIV-specific 133 bp PCR product was correctly amplified until 5 molecules of HA gene as minimum of templates. This kind of PCR was drafted as UPCR in this study and it could be used to detect not only AIV subtype, but also other pathogens using UPCR-based diagnosis.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.449-453
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• 2016

$HA(hydroxyapatite)/{\beta}-TCP$ (tricalcium phosphate) biomaterial (BCP; biphasic calcium phosphate) is widely used as bone cement or scaffolds material due to its superior biocompatibility. Furthermore, $NH_4HCO_3$ as a space holder (SH) has been used to evaluate feasibility assessment of porous structured BCP as bone scaffolds. In this study, using a spark plasma sintering (SPS) process at 393K and 1373K under 20MPa load, porous $HA/{\beta}-TCP$ biomaterials were successfully fabricated using $HA/{\beta}-TCP$ powders with 10~30 wt% SH, TiH2 as a foaming agent, and MgO powder as a binder. The effect of SH content on the pore size and distribution of the BCP biomaterial was observed by scanning electron microscopy (SEM) and a microfocus X-ray computer tomography system (SMX-225CT). The microstructure observations revealed that the volume fraction of the pores increased with increasing SH content and that rough pores were successfully fabricated by adding SH. Accordingly, the cell viabilities of BCP biomaterials were improved with increasing SH content. And, good biological properties were shown after assessment using Hanks balanced salt solution (HBSS).

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.1-10
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• 2001

This study was performed to evaluate chromium in air and chromium concentrations in whole blood and urine of workers at chrome plating factories, and to determine the correlation between environmental and biological chromium levels. This study involved 29 workers as study group and 24 undergraduate students as control group. The geometric means(GM) of airborne hexavalent chromium and total chromium concentrations in the plating factories were 3.4 $\mu\textrm{g}$/㎥ and 10.8 $\mu\textrm{g}$/㎥, respectively. Hexavalent chromium levels in two of total 29 measurements exceeded the korean occupational exposure limit and the American Conference of Governmental Industrial Hygienists Threshold Limit Value(ACGIH-TLV) of 50$\mu\textrm{g}$/㎥. Only one sample for total chromium exceeded the Korea occupational exposure limits, the ACGIH-TLV, and the National Institute for Occupational Safety and Health Recommended Exposure Limits(NIOSH-REL) of 500 $\mu\textrm{g}$/㎥. The GM of chromium concentrations in blood and urine of workers exposed to chromium were 8.4 $\mu\textrm{g}$/L and 11.9 $\mu\textrm{g}$/L. The GM of chromium concentrations in blood and urine of workers exposed to chromium were 8.4 $\mu\textrm{g}$/L and 11.9 $\mu\textrm{g}$/L, respectively, whereas the chromium concentrations in blood and urine of the controls were 1.6 $\mu\textrm{g}$/L and 3.8 $\mu\textrm{g}$/L, respectively. There were statistically significant differences of blood and urine concentrations between study group and control group (p<0.01). The chromium concentrations in urine were most highly related to hexavalent chromium, concentration in air(r=0.642, p<0.01). Also, there was a relatively high correlation between the hexavalent chromium concentrations in air and chromium concentrations in whole blood(r=0.557, p<0.05). These results indicate that whole-blood chromium with urinary chromium could be an indicator of chromium body burden caused by exposure to chromic acid mist in plating operation.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1107-1114
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• 2016

This research, sponsored by the Korean Ministry of Environment in 2014, was the first epidemiological study in Korea that investigated the health impact assessment of radon exposure. Its purpose was to construct a model that calculated the annual mean cumulative radon exposure concentrations, so that reliable conclusions could be drawn from environment-control group research. Radon causes chronic lung cancer. Therefore, the long-term measurement of radon exposure concentration, over one year, is needed in order to develop a health impact assessment for radon. Hence, based on the seasonal correction model suggested by Pinel et al.(1995), a predictive model of annual mean radon concentration was developed using the year-long seasonal measurement data from the National Institute of Environmental Research, the Korea Institute of Nuclear Safety, the Hanyang University Outdoor Radon Concentration Observatory, and the results from a 3-month (one season) survey, which is the official test method for radon measurement designated by the Korean Ministry of Environment. In addition, a model for evaluating the effective annual dose for radon was developed, using dosimetric methods. The model took into account the predictive model for annual mean radon concentrations and the activity characteristics of the residents.

• Journal of Oriental Neuropsychiatry
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• v.24 no.1
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• pp.131-144
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• 2013

Objectives : To provide information on the safety of ACM, we carried out a single oral dose-increasing toxicity and 4-weeks repeated oral dose determining test of ACM in beagle dogs. Methods : In a single oral dose-increasing toxicity test, beagles were treated with ACM orally increasing dose level (1,000, 2,000, 5,000 mg/㎏) at interval of 3 days. After administration, signs of toxicity were observed for two weeks. In 4-weeks repeated oral dose determinating test, beagles were treated with ACM with oral dose 500, 1,000, 2,000 mg/kg for 4 weeks. Mortality, clinical signs, body weight changes, food consumption, urinalysis, hematological and biochemical parameters, organ weights, necropsy findings, and histological findings were monitored during the study period. Results : In a single oral dose-increasing toxicity test, we found no mortality, abnormalities in clinical signs, body weight, and necropsy findings during the study period. In 4-weeks repeated oral dose determinating test, we found no mortality, abnormalities in clinical signs, body weight, food consumption, urinalysis, hematological and biological parameters, gross findings, organ weights, necropsy findings, and histopathological findings in any of the beagles tested. Conclusions : The results obtained in these studies suggest that maximum tolerated dose (MTD) of ACM in male and female beagle dogs was supposed to be over 5,000 mg/kg. For the future studies of toxicity, it is advisable that high dose and low dose are set at 2000 mg/kg and 500 mg/kg, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.498-498
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• 2013

Atmospheric Pressure Plasmas have pioneered a new field of plasma for biomedical application bridging plasma physics and biology. Biological and medical applications of plasmas have attracted considerable attention due to promising applications in medicine such as electro-surgery, dentistry, skin care and sterilization of heat-sensitive medical instruments [1]. Traditional approaches using electronic devices have limits in heating, high voltage shock, and high current shock for patients. It is a great demand for plasma medical industrial acceptance that the plasma generation device should be compact, inexpensive, and safe for patients. Microwave-excited micro-plasma has the highest feasibility compared with other types of plasma sources since it has the advantages of low power, low voltage, safety from high-voltage shock, electromagnetic compatibility, and long lifetime due to the low energy of striking ions [2]. Recent experiment [2] shows three-log reduction within 180-s treatment of S. mutans with a low-power palm-size microwave power module for biomedical application. Experiments using microwave plasma are discussed. This low-power palm-size microwave power module board includes a power amplifier (PA) chip, a phase locked loop (PLL) chip, and an impedance matching network. As it has been a success, more compact-size module is needed for the portability of microwave devices and for the various medical applications of microwave plasma source. For the plasma generator, a 1.35-GHz coaxial transmission line resonator (CTLR) [3] is used. The way of reducing the size and enhancing the performances of the module is examined.