• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.138-148
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• 2022

Purpose This study evaluated the rates and annual trends of pediatric CT scans in South Korea using a nationwide population-based database. Materials and Methods Data regarding pediatric CT scan usage between 2012 and 2017 were retrieved from the health insurance review and assessment service. Data on the age, sex, diagnosis, and the anatomical area of involved patients were also extracted. Results A total of 576376 CT examinations were performed among 58527528 children aged below 18 years (9.8 scans/1000 children), and the number of CT examinations per 1000 children was noted to have increased by 23.2% from 9.0 in 2012 to 11.0 in 2017. Specifically, the number of CT examinations increased by 32.9% for the 6-12 years of age group (7.4/1000 to 9.8/1000) and by 34.0% for the 13-18 years of age group (11.4/1000 to 15.3/1000). Moreover, majority of the CT scans were limited to the head (39.1%), followed by the extremities (32.5%) and the abdomen (13.7%). Notably, the number of extremity CT scans increased by 83.6% (2.3/1000 to 4.2/1000), and its proportion as compared to other scans increased from 25.3% to 37.7%. Conclusion CT scans in the pediatric population increased continuously from 2012 to 2017 at an annual rate of 4.4%. Therefore, physicians should balance the benefits of CT with its potential harms from associated radiation exposure in pediatric patients.

• Development and Reproduction
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• v.15 no.4
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• pp.365-371
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• 2011

Water temperature governs various biological events in many aquatic animals including fish. Temperature changes the rates of gametogenesis and development, in some cases, is even capable of reversing fish sex. Treatments of fish with unusually high temperature are known to induce the expression of HSP70 gene. Development of an effective inhibitor for HSP70 gene expression is, thus, crucial to study the role of HSP70 in the temperature sensitive biological events. We have investigated the inhibitory effect of quercetin, 3,3',4',5,7-pentahydroxyflavon, a natural flavonid, on the expressions of HSP70 gene induced by high temperature ($36^{\circ}C$) in the Nile tilapia, Oreochromis niloticus, larvae and juveniles (10~13 cm in total length). The expression of HSP 70 gene was significantly decreased in tilapia larvae immersed in 50 ${\mu}M$ or 100 ${\mu}M$ quercetin solution for 6 hours before the exposure to high temperature (P<0.05). In particular, the level of HSP70 expression in fish treated with 100 ${\mu}M$ was as low as that of fish without high temperature treatment. Juveniles of tilapia were individually injected with 0.1 $m{\ell}$ of either 0.5 mM, 5 mM or 20 mM of quercetin solution before the exposure to high temperature. As the results, the expression of HSP70 gene in the gonad and brain of juvenile fish was significantly inhibited by the injection of 0.5 mM quercetin solution (P<0.05), but not by higher concentrations. We report, for the first time in the fish, that quercetin effectively inhibits the expression of HSP70 gene induced by high temperature and 100 ${\mu}M$ for the immersion of larvae and 0.5 mM for the injection to juvenile can be used for the effective concentrations for the study of temperature sensitive biological events in tilapia.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.349-357
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• 1998

This study was to investigate whether the viability of Hanwoo IVM/IVF/IVC blastocysts was maintained after vitrification and thawing. In vitro produced Hanwoo blastocysts were vitrified by two-step method: equilibrated in EG20 for 3 min, and then exposed in EFS40 ［40% ethylene glycol (EG), 18% ficoll and 10.26% sucrose in mDPBS containing 10% FBS ］and vitrified in L$N_2$for 30 - 45 sec. After thawing, in vitro survival was assessed as the re-expanded and hatched rates at 24 hand 48 h, respectively. The results obtained in these experiments were summarized as follows: From the 12 replicates, 52.5% of Hanwoo blastocysts were produced in vitro at day 7 after IVF. When the effects of freezing solution to the embryo survival were examined, there is no significant toxicity in exposure (100.0, 73.8%) compared to that af control group (100.0, 87.0%). However, when embryos were vitrified, high survival (86.2, 55.4%) was obtained although it was significantly lower than those of exposure and control group (p＜0.05). When the in vitro survival of vitrified embryos according to developmental stage and culture day were examined, it showed that more advanced embryo stage exhibited a significantly higher survival rate irrespective of culture day (p＜0.05). Also, even in the same development stage, the in vitro survival of day 7 embryos (re-expanded: 75.0~87.5%, hatched: 21.4~66.7%) was higher than those of day 8 embryos(re-expanded: 58.6~78.3%, hatched: 10.3~52.2%). Therefore, these results suggested that in vitro produced Hanwoo blastocysts can be successfully cryopreserved by simple two-step vitrification method using EFS40 freezing solution, particularly at the expanded and early hatching blastocyst stage regardless of embryo culture duration (day 7 or day 8 after IVF).

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.50-56
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• 2012

Purpose: Those who access to the nuclear medicine department are classified as radiation workers, temporarily access group, and occasional access group as defined by the atomic energy law. The radiation workers and temporarily access people wear a personal radiation dosimeter for checking their own radiation absorbed dose periodically. However, because of the sanitation workers, classified as temporarily access group, who are working in the nuclear medicine department are moved in a cycle with other departments and their works are changeful, it is hard to control their radiation absorbed dose. Thus, this study is going to examine the state of the sanitation worker's radiation absorbed dose, and then make sure whether they are classified as temporarily access group or not. Materials and methods: In the first instance, the first sanitation worker who works in vitro laboratory and PET room and the second sanitation worker who works in gamma camera rooms (invivo room) wore radiation dosimeter-OSL(Optically Stimulated Luminescence)- to measure their own radiation absorbed dose during work time from May to June 2011. Secondly, this study was taken place 5 places in gamma camera rooms, 2 places in PET bed room, operating room, waiting room and cyclotron room in PET and 4 places in vitro laboratory. And then to measure the radiation space dose rate, it is measured 10 times each of places as sanitation worker's work flow by using radiation survey meter. Results: The radiation absorbed dose on OSL of the first c who works in vitro laboratory and PET room and the second one who works in gamma camera rooms are 0.04, 0.02 mSv per month respectively. That means the estimated annual radiation absorbed doses are less than 1mSv as 0.48, 0.24 mSv/yr respectively. The radiation space dose rates as sanitation worker's work flow using survey meter are 0.0037, 0.0019 mSv/day, so the estimated annual radiation absorbed dose are 0.93, 0.47 mSv/yr respectively. The weighted exposure dose of first sanitation worker of each places are 1.62% in cyclotron room, 3.88% in waiting room, 2.39% in operating room, 81.01% in bed room of PET and 11.01% in vitro laboratory. The weighted exposure dose of second sanitation worker of each places are 45.22% in radiopharmaceutical laboratory, gamma 30.64% in camera rooms, 15.65% in waiting room, 8.49% in reading room. Conclusion: The annual radiation absorbed doses on OSL of both sanitation workers are less than 1 mSv per year and the annual radiation absorbed doses by using survey meter are less than 1mSv either, but close up to 1 mSv. Thus, to clarify whether the sanitation workers are temporarily access group or not, and to be lessen their s radiation absorbed dose, they should be educated about management of radiation and modified their work flow or work time appropriately, their radiation absorbed dose would be lessen certainly.

• Korean Journal of Environmental Biology
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• v.36 no.1
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• pp.43-49
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• 2018

The toxic assessment of the PBDEs (BDE-47, BDE-209) has been comprehensively investigated by using the rates of survival and population growth in the marine rotifer, Brachionus plicatilis. Chiefly, the survival rate was determined after a measurement of 24 hours of exposure to the BDE-47 (2,2'4,4'-Tetrabromodiphenyl ether) and the BDE-209 (2,2',4,4'-Decabromodiphenyl ether) was performed. The BDE-47 reduced survival rate in dose-dependent manner and a significant reduction were noted to have occurred at a concentration of greater than $3.9mg\;L^{-1}$, but the BDE-209 had no effect which was subsequently observed in this study. The population growth rate (r) was determined after 72 hours of exposure to toxicants in the study. It was observed that the r value in the controls (absence PBDEs) was greater than 0.5, and that it decreased as the dose-dependent manner as recorded. The survival rate when exposed to BDE-47 and BDE-209, $EC_{50}$ value was $13mg\;L^{-1}$ and $>1,000mg\;L^{-1}$, and population growth rate was $3.67mg\;L^{-1}$ and $862.75mg\;L^{-1}$, respectively. Therefore, the BDE-47 is considered to be 76-235 times more harmful than the BDE-209 as noted. In this study, the ecotoxicological bioassay using a noted survival rate and population growth rate of B. plicatilis can be used as a baseline data for the continued establishment of the environmental quality standard of the incidences of the BDE-47 and BDE-209 in a marine environment.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.372-379
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• 2019

We evaluated the toxic effects of phenanthrene (PHE) and zinc undecylenate (ZU) on the population growth rate (r) of the marine diatom, Skeletonema costatum. The r of S. costatum was determined after 96 hrs of exposure to PHE (0, 25, 50, 100, 200 and 300 mg L^-1) and ZU (0, 5, 10, 15, 20 and 25 mg L^-1). The results showed that r in the control (the absence of PHE and ZU) was greater than 0.04, while r in the treatment groups decreased with increasing PHE and ZU concentrations. PHE and ZU were shown to reduce r in a dose-dependent manner, with significant decreases occurring at concentrations above 50 and 10 mg L^-1, respectively. The EC₅₀ values of r in PHE and ZU exposure were 136.13 and 16.95 mg L^-1, respectively. The no observed effect concentrations (NOEC) were 25 and 5 mg L^-1, and the lowest observed effect concentrations (LOEC) were 50 and 10 mg L^-1. These results indicated that concentrations of greater than 50 mg L^-1 of PHE and 10 mg L^-1 of ZU in marine ecosystems induced a toxic effect on the r of S. costatum. These results can serve as useful baseline data for the establishment of safety concentrations of PHE and ZU in marine ecosystems.

• Journal of Nutrition and Health
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• v.44 no.5
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• pp.443-452
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• 2011

The characteristics of pesticide residues were examined in 18,069 samples from 91 vegetable commodities collected in Seoul from 2007 to 2009, and the vegetable dietary intakes of Seoulites were estimated using the Korea National Health and Nutrition examination survey data from 2008. The hazard index was calculated using vegetable pesticide residues and dietary vegetable intake by Seoulites. Detection rates for pesticide residues in vegetables were 11.2 % in 2007, 8.6 % in 2008, and 12.0 % in 2009. Excess rate of Maximum Residue Limits tended to decline from 4.6 % in 2007, to 2.8 % in 2008, and 2.1 % in 2009.Daily vegetable intake for Seoulites was 288.12 ${\pm}$ 214.8 g, and vegetable intake by males was more than that of females (p < 0.001). The hazard index was the highest at $2.76{\times}10^{-2}$ in 2007, and the lowest at $1.69{\times}10^{-2}$ in 2009. The risks caused by multiple pesticides in vegetables were very low and vegetable intake was safe considering the hazard index values.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.253-260
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• 2013

Purpose: To investigate the UV-B blocking rate of eyeglasses lens which can prevent enzymes denaturation in cornea. Methods: The denaturation degree of RNase A and catalase, superoxide dismutase (SOD) was determined by using Acrylamide gel electrophoresis after UV-B irradiation of 312 nm for 1, 3, 6, 24 and 96 hours. Also, the inhibitory effect of eyeglasses lens having UV-B blocking rate of 50%, 80%, 95% and 99% on the enzymes denatration was measured. Results: The denaturation of RNase A was induced by 1 hour-irradiation of UV-B. To inhibit RNase A denaturation after UV-B irradiation between 1 hour and 6 hours, UV-B blocking lens of 95% were effective. UV-B blocking lens of 99% suppressed the inhibition of RNase A denaturation after the UV-B exposure between 24 hours and 96 hours. The denaturation of catalase was not induced by 1 hourirradiation of UV-B. To inhibit enzyme denaturation after UV-B irradiation between 1 hour and 6 hours, UV-B blocking lens of 50% were effective. UV-B blocking lens of 95% suppressed the inhibition of enzyme denaturation induced by UV-B irradiation between 24 hours and 96 hours. The SOD denaturation was not induced by UV-B irradiation shorter than 6 hours exposure. The UV-B blocking lens of 50% could inhibit SOD denaturation after the UV-B irradiation for 24 hours. When SOD was exposed to UV-B for 96 hrs, SOD denaturation was inhibited by eyeglasses lens with UV blocking rate higher than 95%. Conclusions: The results demonstrated that the proper UV-B blocking rates of eyeglasses lens to inhibit the enzymes denaturatioin was different according to the types of enzymes and its inhibitory effect was effective only when eyeglasses lens had higher than certain UV-B blocking rate.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.467-475
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• 2020

The purpose of this study is to assess doses to ¹⁸F-FDG, a radioactive drug, during PET examinations, to alleviate anxiety about radiation in patients and carers, to minimize the indiscriminate examination progress caused by medical institution personnel and space clearance problems, and health examination. The dose assessment was measured using a thermo-fluorescent dosimeter (TLD) and an electronic personal dosimeter (EPD) at the location of the cervical (hypothyroid), thorax (heart), and lower abdomen (breeding line) which are the three highest tissue areas of the radiation tissue weighting. In addition, spatial dose rates and radioactivity in urine were measured using GM counters and ion boxes. The results are as follows: First, the personal dosimeter TLD was measured 0.0425±0.0277 mSv in the cervical region, 0.0440±0.0386 mSv in the thorax and 0.0485±0.0436 mSv in the lower abdomen, with little difference in the heart dose depending on radiation sensitivity. The EPD was measured at 0.942±0.141 mSv/h immediately after the cervical position, and 0.192±0.031 mSv/h after 120 minutes. Immediately after the thorax position, 0.516±0.085 mSv/h, 120 minutes later 0.128±0.040 mSv/h. Immediately after the lower abdomen position, 0.468±0.091 mSv/h, and after 120 minutes 0.105±0.021 mSv/h were measured. The spatial dose rate at the GM counter was measured immediately at 0.041±0.005 mSv/h, 120 minutes later at 0.014±0.002 mSv/h. The radioactivity in urine using ion chamber was measured at 0.113±0.24 MBq/cc after 60 minutes and 0.063±0.13 MBq/cc after 120 minutes. As a result, ¹⁸F-FDG should be administered, dose re-evaluated two hours after the PET test is completed, and caregivers should be avoided. In addition, it is deemed necessary to provide patients and carers with sufficient explanations and expected values of exposure dose to avoid reckless testing. It is hoped that the data tested in this study will help patients and families relieve anxiety about radiation, and that the radiation workers' exposure management system and institutional improvements will contribute to the development of medical radiation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.496-504
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• 1997

This study was carried out to estimate toxic effects of phenol on survival and metabolism of the abalone juvenile, Haliotis discus hannai. The experiment was conducted by renewal bioassay procedure with different salinities at $20^{\circ}C$. The $LC_{50}$ of the juvenile exposed to phenol in the range of 0.5 and $100mg/\ell\;was\;34.3\~6.5mg/\ell\;at\;2.4\%_{\circ}\;and\;52.2\~9.3m/\ell\;at\;32\%_{\circ}$ salinity with exposure time from 24 hours to 96 hours. $LT_{50}$ was remarkablely reduced with increase of phenol conentration and decrease of salinity. Lethal toxicity or phenol was higher at low salinity than at high salinity. Therefore, salinity is likely to be one of factor to increase phenol toxicity. The oxygen consumption of the juvenile was reduced with increase of phenol concentration and with decrease of salinity. In spite of phenol toxicity, the oxygen consumption of the juvenile exposed to phenol of low concentration was high and similar as compared with that of control group. Survival rates of the abalone kept in phenol-free sea water after exposure to phenol concentration of 5, 10 and $20mg/\ell$ for 96 hours were reduced with decrease of salinity. Durations required to recover the normal metabolic rate of the juvenile, which was exposed to phenol concentration of 5, 10 and $20mg/\ell$ for 96 hours, were made longer with increasing phenol concentration. In the case of the juvenile exposed to sublethal concentration of phenol for 15 days, it were elongated as compared with that of the abalone exposed to phenol concentration caused acute toxicity. The result of this experiment indicated that relatively low concentration of phenol can impact on the abalone juvenile in marine ecosystem.