• Fire Science and Engineering
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• v.22 no.5
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• pp.48-54
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• 2008

Forest fires occur the world over, with large-scale fires constantly breaking out. A suppressant a type of forest fire chemical is widely used to respond to fires rapidly and effectively. In general, suppressants used for fires have been divided into dry powder, liquid, foam, and gel type, according to physical form and use. This study has conducted toxicity tests relating to phytotoxicity(Pinus densiflora seed germination rate and mortality of containerized seedling), and soil organism toxicity(earthworm acute toxicity tests), of these suppressants, with the loaded stream suppressant for direct forest fire extinguishing a Loaded Stream and foam concentrates generally being used in Korea. From the results of the tests, the loaded stream and the foam concentrate had an effect on the toxicity levels. In the case of the loaded stream type, it was observed that toxicity indicating a 100% lethality rate was found among all toxicity test methods. Therefore, it is determined that forest ecology environmental toxicity impact assessments related to the suppressant used to extinguish forest fires are necessary in the near future.

• The Journal of the Korean Society for Microbiology
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• v.35 no.4
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• pp.317-324
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• 2000

Candida albicans is one of the most frequently isolated fungal pathogens in human. Recently, the prevalence of candida infection has markedly increased, partially due to the increase of immunocompromised hosts. Proposed virulence factors of the pathogenic Candida are the ability to form hyphae to adhere to epithelial cell surfaces, and to secrete acid proteinases and phospholipases. We measured the relative cell surface hydrophobicity (CSH) and the ability of proteinase production (PROT), phospholipase production (PLase), adherence to host epithelium (ADH), and hyphal transition (Germ). The relative risk of virulence factors was analyzed by lethality test in murine model of hematogeneously disseminated candidal infection. According to Cox's proportional hazard analysis, the statistically significant virulence factors were PROT, ADH, and CSH. PROT was the highest risk factor of them. To evaluate the applicability for the diagnosis and treatment of Candidiasis, we examined the protective effect of the active and passive immunizations with the materials purified from virulence factors and antibodies to them in Candia-infected mice model. The mean survival times of active and passive immunized groups were slightly longer than those of non-immunized groups.

• Korean Journal of Clinical Laboratory Science
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• v.44 no.2
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• pp.59-65
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• 2012

Previous studies have shown that modified Je-Ho-Tang (MJHT) has anti-platelet effects. Je-Ho-Tang (JHT), a Korean court beverage, is a traditional Korean herbal medicine that has been used for the treatment of a disease attended by great thirst, and for prevention of illness in hot summers. We made MJHT from JHT by excluding honey. The present study was performed to determine the acute oral toxicity of crude extract of MJHT in male and female ICR mice. We investigated the in vivo single dose acute toxicity of MJHT hot-water extraction. This test was orally administered once by gavage to 20 mice of each sex received doses of 0 (control group), 1250, 2500 and 5000 mg/kg body weight. Mortalities, clinical findings, autopsy findings and body weight changes were monitored daily for 14 days following the administration. We observed survival rates, general toxicities, changes of body weight, and autopsy. No significant lethality was observed after single oral administration of MJHT at the different dosages. Autopsies on the animals revealed no gross abnormalities. Therefore, the LD50 value of MJHT for ICR mice was estimated more than 5000 mg/kg by the oral route. These results suggest that no toxic dose level of MJHT in mice is considered to be more than 5000 mg/kg. Consequently, it was concluded that MJHT have no effect on acute toxicity and side effect in ICR mice.

• Entomological Research
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• v.48 no.6
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• pp.533-539
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• 2018

The RNA interference (RNAi) has been considered as an important genetic tool and applied to develop a new living modified (LM) crop trait which is an improvement of nutrient quality or pest management. The RNAi of DvSnf7 has been used for resistance to LM maize and the Western Corn Rootworm which is a major agricultural pest for the US Corn Belt. Most of the environmental risk assessments (ERA) of double strand RNA (dsRNA) have been performed using in vitro transcript products, and not in vivo expressed product. A large amount of dsRNA was required for the acute toxicity assay of water fleas. Therefore development of massive dsRNA purification techniques is critical. Daphnia, a freshwater microcrustacean, is a model organism for studying cellular and molecular mechanism involved in life history traits and ecotoxicology. In this study, we established the massive dsRNA purification method using Escherichia coli and implemented acute toxicity assays to Daphnia magna. As a result, the present RNase A and DNase I, dsRNA was efficiently purified without any special techniques or equipment. Even though purified dsRNA existed during the acute toxicity test, lethality or abnormal behavior were not observed in D. magna. These results indicated that GFP and DvSnf7 dsRNA were not significantly affected to D. magna due to their lack of sequence matching in its genome. The purification method of dsRNA and the acute toxicity assay of water fleas using purified dsRNA would be suitable for the toxicological studies of LMOs to aquatic non-target organisms.

• Structural Engineering and Mechanics
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• v.77 no.4
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• pp.441-461
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• 2021

Reinforced concrete (RC) columns are crucial in building structures and they are of higher vulnerability to terrorist threat than any other structural elements. Thus it is of great interest and necessity to achieve a comprehensive understanding of the possible responses of RC columns when exposed to high intensive blast loads. The primary objective of this study is to derive analytical formulas to assess vulnerability of RC columns using an advanced numerical modelling approach. This investigation is necessary as the effect of blast loads would be minimal to the RC structure if the explosive charge is located at the safe standoff distance from the main columns in the building and therefore minimizes the chance of disastrous collapse of the RC columns. In the current research, finite element model is developed for RC columns using LS-DYNA program that includes a comprehensive discussion of the material models, element formulation, boundary condition and loading methods. Numerical model is validated to aid in the study of RC column testing against the explosion field test results. Residual capacity of RC column is selected as damage criteria. Intensive investigations using Arbitrary Lagrangian Eulerian (ALE) methodology are then implemented to evaluate the influence of scaled distance, column dimension, concrete and steel reinforcement properties and axial load index on the vulnerability of RC columns. The generated empirical formulae can be used by the designers to predict a damage degree of new column design when consider explosive loads. With an extensive knowledge on the vulnerability assessment of RC structures under blast explosion, advancement to the convention design of structural elements can be achieved to improve the column survivability, while reducing the lethality of explosive attack and in turn providing a safer environment for the public.

• Journal of Pharmacopuncture
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• v.17 no.1
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• pp.27-34
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• 2014

Objectives: This experiment was conducted to examine the toxicity of Water soluble Carthmi-Flos herbal acupuncture (WCF) by administering a single intramuscular dose of WCF in 6-week-old, male and female Sprague-Dawley rats and to find the lethality dose for WCF. Methods: The experiment was conducted at Biotoxtech according to Good Laboratory Practices under a request by the Korean Pharmacopuncture Institute. This experiment was performed based on the testing standards of "Toxicity Test Standards for Drugs" by the Ministry of Food and Drug Safety. Subjects were divided into 4 groups: 1 control group in which normal saline was administered and 3 test groups in which 0.1, 0.5 or 1.0 mL of WCF was administered; a single intramuscular dose was injected into 5 males and 5 females in each group. General symptoms and body weights were observed/measured for 14 days after injection. At the end of the observation period, hematological and clinical chemistry tests were performed, followed by necropsy and histopathological examinations of the injected sections. Results: No mortalities were observed in any group. Also, symptoms, body weight, hematology, clinical chemistry and necropsy were not affected. However, histopathological examination of the injected part in one female in the 1.0-mL group showed infiltration of mononuclear cells and a multi-nucleated giant cell around eosinophilic material. Conclusion: Administration of single intramuscular doses of WCF in 3 groups of rats showed that the approximate lethal dose of WCF for all rats was in excess of 1.0 mL, as no mortalities were observed for injections up to and including 1.0 mL.

• Toxicological Research
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• v.34 no.3
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• pp.191-197
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• 2018

In 2015, a candidate for the second national reference standard (NRS) of Gloydius snake venom was produced to replace the first NRS of Gloydius snake venom. In the present study, the potencies of the candidate were determined by a collaborative study, and the qualification of the candidate was estimated. The potencies of the candidate were determined by measuring the murine lethal titers and lapine hemorrhagic titers of venom against the regional working reference standard (RWRS) for antivenom using the methods described in the previous report for the first NRS of Gloydius snake venom. Three Korean facilities contributed data from a total of 30 independent assays. Subsequently, two foreign national control research laboratories contributed to this collaborative study. The results were calculated using the Reed-Muench method for lethality and determined using a mixed-effects model for hemorrhage. The general common potencies of the lethal and hemorrhagic titers were obtained from the results of the 30 tests performed at three Korean facilities. The results are expressed in micrograms for 1 test dose (TD) with a 95% confidence interval as follows: a lethal titer of $90.13{\mu}g/TD$ (95% confidence interval = $87.39{\sim}92.86{\mu}g$) and a hemorrhagic titer of $10.80{\mu}g/TD$ (95% confidence interval = $10.46{\sim}11.14{\mu}g$). In addition, the candidate preparation showed good quality evaluation according to the results of the quality estimation of the candidate and is judged to be suitable to serve as the Korean NRS for snake venom. In conclusion, the second NRS of Gloydius snake venom was established in this study and will be used for national quality control, including a national lot release test of Korean antivenom products.

• Advances in Traditional Medicine
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• v.3 no.3
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• pp.157-162
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• 2003

Various extracts of higher plants have been used in traditional medicine systems for centuries. While tropical and sub-tropical plants have received considerable attention from the researchers for evaluation of their bioactivity, temeperate plants have always been neglected somewhat. Similarly, seeds of the plants have not been considered seriously compared to other plant parts, e.g. leaves, stems, roots, flowers, etc. as a potential source for biologically active compounds. As part of our on-going evaluation of the extracts of the seeds of temperate plants, especially from Scotland, for biological activity, Achillea millefolium, Angelica sylvestris and Phleum pratense have been chosen for the present study. Both A. millefolium and A. sylvestris are well known for their traditional medicinal uses in Europe and also in the orient, but there is no report on any medicinal properties of P. pratense available to date. Extracts of the seeds of these plants have been assessed for their antioxidant and antibacterial potential and also for general toxicity. Both DCM and MeOH extracts of A. millefolium showed the most significant broad spectrum antibacterial activity among the three plants and inhibited the growth of almost all test strains of bacteria. The DCM extracts of all three species were active against methicillin resistant Staphylococcus aureus (MRSA) and Citrobacter freundii $(MIC=6.25{\times}10^{-1}\;mg/mL)$. While the MeOH extracts of A. millefolium and P. pratense were active against C. freundii, that of P. pratense was also active against MRSA. The MeOH extract of A. sylvestris did not show any antibacterial activity against any of the eight bacterial strains at test concentrations. The MeOH extract of P. pratense showed the most prominent antioxidant activity $(IC_{50}=145\;{\mu}g/ml)$ and there was no antioxidant activity observed with the DCM extract of A. millefolium. The DCM extract of P. pratense was the most toxic $(LC_{50}=20\;{\mu}g/ml)$ among the extracts.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1271-1279
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• 2009

To develop low endotoxic and multi-immunogenic outer membrane vesicles (OMVs), a deletion mutant of the msbB gene in Salmonella enterica serovar Typhimurium (S. Typhimurium) was used as a source of low endotoxic OMV, and an expression vector of the canine parvovirus (CPV) VP2 epitope fused to the bacterial OmpA protein was constructed and transformed into the Salmonella ${\Delta}msbB$ mutant. In a lethality test, BALB/c mice injected intraperitoneally with the Salmonella ${\Delta}msbB$ mutant survived for 7 days, whereas mice injected intraperitoneally with the wild type survived for 3 days. Moreover, all mice inoculated orally with the ${\Delta}msbB$ mutant survived for 30 days, but 80% of mice inoculated orally with the wild type survived. The OmpA::CPV VP2 epitope fusion protein was expressed successfully and associated with the outer membrane and OMV fractions from the mutant S. Typhimurium transformed with the fusion protein-expressing vector. In immunogenicity tests, sera obtained from the mice immunized with either the Salmonella msbB mutant or its OMVs containing the OmpA::CPV VP2 epitope showed bactericidal activities against wild-type S. Typhimurium and contained specific antibodies to the CPV VP2 epitope. In the hemagglutination inhibition (HI) assay as a measurement of CPV-neutralizing activity in the immune sera, there was an 8-fold increase of HI titer in the OMV-immunized group compared with the control. These results suggested that the CPV-neutralizing antibody response was raised by immunization with OMV containing the OmpA::CPV VP2 epitope, as well as the protective immune response against S. Typhimurium in BALB/c mice.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.631-636
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• 2002

Lethality of high intensity light pulse on the pre-determined microbial populations has been investigated. Prior to the treatment, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Pediococcus pentosaceus were cultivated separately onto the surface of Lactobacilli MRS agar. Pre-determined microbial populations were applied to the test media and these sample were exposed to high intense light source with an exposure time ranging from 1 to $2500\;{\mu}s$. Results showed that at least 200 light pulses of $1\;{\mu}s$ duration were required to reduce L. Plantarum cells by 90% at 25 kV, the greater the number of light pulses, the larger the reduction in viable cell numbers. Viable cells of L. plantarum and the others were reduced by more than 5 and 6 log cycles at the upper exposure level of $750\;{\mu}s$, respectively. These study shows that pulsed light emissions can significantly reduce populations of lactic acid bacteria on exposed surface with exposure times. Killing efficiency for L. plantarum significantly increased with decreasing the distance between the lamp and the surface of samples.