• Imaging Science in Dentistry
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• v.43 no.3
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• pp.179-184
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• 2013

Purpose: X-ray exposure should be clinically justified and each exposure should be expected to give patients benefits. Since dental radiographic examination is one of the most frequent radiological procedures, radiation hazard becomes an important public health concern. The purpose of this study was to investigate the attitude of Korean dentists about radiation safety and use of criteria for selecting the frequency and type of radiographic examinations. Materials and Methods: The study included 267 Korean dentists. Five questions related to radiation safety were asked of each of them. These questions were about factors associated with radiation protection of patients and operators including the use of radiographic selection criteria for intraoral radiographic procedures. Results: The frequency of prescription of routine radiographic examination (an example is a panoramic radiograph for screening process for occult disease) was 34.1%, while that of selective radiography was 64.0%. Dentists' discussion of radiation risk and benefit with patients was infrequent. More than half of the operators held the image receptor by themselves during intraoral radiographic examinations. Lead apron/thyroid collars for patient protection were used by fewer than 22% of dental offices. Rectangular collimation was utilized by fewer than 15% of dental offices. Conclusion: The majority of Korean dentists in the study did not practice radiation protection procedures which would be required to minimize exposure to unnecessary radiation for patients and dental professionals. Mandatory continuing professional education in radiation safety and development of Korean radiographic selection criteria is recommended.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.199-199
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• 2013

The distinctive cellular and mitochondrial dysfunctions of a human epithelial lung cancer cell line (H460) from a human lung fibroblastic normal cell line (MRC5) have been studied by dielectric barrier discharge (DBD) plasma treatment. The DBD plasma device have generated large amount of H2O2 and NOx in culture media which is dependent on plasma exposure time. It is found that the cell number of lung cancer cell H460 has been reduced more than the lung normal cell MRC5 as being increased exposure and incubation time. Also these both cell lines have showed mitochondria fragmentation under 5 minutes' plasma exposure, which is a clue of apoptosis. It is noted in this study that AnnexinV staining has showed not only early apoptosis, but also late apoptosis in lung cancer cell H460. Mitochondria enzyme activity and ATP generation have been also much reduced in lung cancer cell H460. Their mitochondrial membrane potential (${\Delta}{\psi}m$) has been found to be reduced in magnitude and shifted to the induced-potential level of cccp, while MRC5 mitochondrial membrane potential has been shifted slightly to that. These distinctively selective responses of lung cancer cell H460 from lung normal cell MRC5 gives us possibility of applying plasma to cancer therapy.

• Analytical Science and Technology
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• v.26 no.5
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• pp.315-325
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• 2013

The possibility of acute hepatotoxicity caused by dimethylformamide (DMF) requires regular monitoring of the workers who are using DMF to prevent the occupational disease. The authors performed ambient and biological monitoring of workers involved in synthetic leather manufacturing processes using DMF to assess the correlation between the markers of ambient and biological monitoring of DMF. The authors monitored 142 workers occupationally exposed to DMF from 19 workshops in the synthetic leather and ink manufacturing industries located in northern region of Gyeonggi-do. The subjects answered questionnaire on work procedure and use of personal protective equipment to be classified by exposure type. DMF in air samples collected using personal air samplers, diffusive and active sampler, was analysed using gas chromatograph-flame ionization detector (GC-FID) with DB-FFAP column (length 30 m, i.d. 0.25 mm, film thickness 0.25 ${\mu}m$). Urinary N-methylformamide (NMF) was analysed using gas chromatograph-mass selective detector (GC-MSD) at selected ion monitoring (SIM) mode with DB-624 column (length 60 m, i.d. 0.25 mm, film thickness 1.40 ${\mu}m$). Geometric mean (GM) and geometric standard deviation (GSD) of the ambient DMF was $6.85{\pm}3.43$ ppm, and GM and GSD of urinary NMF was $42.3{\pm}2.7$ mg/L. The ratio of subjects with DMF level over 10 ppm was 44%, and those with urinary NMF over 15 mg/L was 87%. NMF in urine adjusted by DMF in air was $4.61{\pm}2.57$ mg/L/ppm and $9.50{\pm}2.41$ mg/L/ppm, respectively, with or without respirator. There was seasonal differences of NMF in urine adjusted by DMF in air, $7.63{\pm}2.74$ mg/L/ppm in summer and $4.53{\pm}2.29$ mg/L/ppm in winter. The urinary NMF concentration which corresponds to 10 ppm of ambient DMF was 52.7 mg/L (r=0.650, n=128). Considering the difference of the route of exposure which resulted from the compliance of wearing personal protective equipment, the estimated contribution of respiratory and dermal exposure route for DMF was 48.5% vs. 51.5%.

• Journal of Life Science
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• v.23 no.2
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• pp.157-166
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• 2013

This study aimed to investigate whether nociceptin contributes to the alterations in cerebral blood flow (CBF) regulation following postnatal exposure to ethanol in Sprague-Dawley rats. Animals received ethanol twice a day, 2 hr apart, on postnatal 6, 7 and 8 days. The changes in regional CBF (rCBF) in response to the changes in mean arterial blood pressure were determined at 4-, 8-, and 12-week of age by laser-Doppler flowmetry. Hypotension was induced by the gradual withdrawal of blood from arterial catheter, and the reversal of blood pressure was produced by the reinfusion of blood. Expression of nociceptin-like immunoreactivity was determined in dura mater and cerebral cortex using immunohistochemistry. Postnatal exposure to ethanol almost abolished the autoregulation of rCBF in all age groups. Pretreatment with nociceptin but not with [$Nphe^1$]nociceptin(1-13)$NH_2$, a selective competitive nociceptin receptor antagonist, 5 min prior to ethanol administration preserved the autoregulation of rCBF in all age groups. Postnatal exposure to ethanol markedly increased the expressions of nociceptin-like immunoreactivity in the dura mater and cerebral cortex, both of which were significantly inhibited by pretreatment with 7-nitroindazole monosodium salt as well as aminoguanidine 5 min prior to ethanol administration in all age groups. The values of arterial blood gas analysis were not significantly different from the basal levels in all groups. These results suggest that nociceptin deeply contributes to the compensatory mechanisms for the nitric oxide-dependent alterations in CBF autoregulation following postnatal exposure to ethanol.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.17-20
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• 2000

We have enhanced the yield of 0.25 ${\mu}{\textrm}{m}$ T-gate $Al_{0.25}$G $a_{0.75}$As/I $n_{0.2}$G $a_{0.8}$As P-HEMT using three-layer E-beam lithography process and selective etching process. The three-layer resist structure (PMMA/copolymer/ PMMA=2000 $\AA$/3000 $\AA$/2000 $\AA$) and three developers (Benzene：IPA=1：1,Methanol：IPA =1：1,MIBK：IPA=1：3) were used for fabrication of a wide-head T-gate by the conventional double E-beam exposure technology. Also 1 wt% citric acid： $H_2O$$_2$：N $H_{4}$OH(200m1：4ml：2.2ml) solution were used for uniform gate recess. The etching selectivity of GaAs over $Al_{0.25}$G $a_{0.75}$As is measured to be 80. So these P-HEMT processes can be used in X-band MMIC LNA fabrication.ion.ion.ion.

• Korean journal of applied entomology
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• v.31 no.3
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• pp.289-303
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• 1992

Investigation of the environmental impact of widespread pesticide use has revealed a virtue/vice relationship. Although many pesticides perform their function and disappear without harm to the environment, others persist beyond their useful purpose and cause direct of indirect hazard to man, domestic animals and wildlife. Concurrently, many pests have rapidly adjusted to chemical control practices through changes in behavior that avoid exposure to pesticides of throuth genetic selection for populations resistant to the toxicants. The prospect of losing control over insect herbivores and desease vectors and returning to the days of global hunger and disease is unthinkable. Fortunately, from basic studies of insect and plant biology many opportunities for the development of safe, selective and environmentally pacific strategies for insect pest management are being realized.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2819-2822
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• 2013

In this study, antiproliferative effects of the selective estrogen receptor modulator Tamoxifen and the aromatase inhibitor letrozole (Femara) were evaluated and compared using the FM3A cell line, originating from a C3H mouse mammary carcinoma and positive in terms of estrogen receptor (ER) expression. Cell kinetic parameters including labelling index, mitotic index and labelling index were assessed after exposure of the. FM3A cell line to $0.001{\mu}g/ml$ of Tamoxifen and $0.25{\mu}g/ml$ of Femara for 4, 8, 16 and 32 h for all parameters. The results showed that cell growth was inhibited by both agents. There was a significant decrease in labelling index and mitotic index and significant increase in apoptotic index for all experimental groups. The differences between control and all experimental groups were statistically significant (p<0.001) for all applications.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.135-140
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• 2014

A bent-shape triazolyl derivative was synthesized via click chemistry, and its photophysical property was investigated in various solvents. In contrast to the invisible ultraviolet emission of other solutions, the chloroform solution exhibited a blue light emission at 460 nm. Furthermore, the blue fluorescence intensified as the UV exposure time at 365 nm increased. On the basis of $^1H$-NMR, pH paper, and acid-addition studies, we confirmed that chloroform was decomposed into HCl with the aid of the triazolyl derivative. The density functional theory calculations suggested that the eye-detectable blue fluorescence was attributed to an intramolecular charge transfer process of the protonated triazolyl derivative in the chloroform solution.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.321-329
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• 2009

Following their applications in cardiology, ophthalmology and dentistry among others, the advent of lasers in dermatology and urology had become the success story of the past decade. Laser-assisted treatments in dermatology and urology are mainly based on the laser-induced tissue injury/coagulation and/or ablation, depending upon the desirable clinical endpoint. In this review, we discussed the underlying mechanisms of the laser induced tissue ablation. In any medical laser application, the controlled thermal injury and coagulation, and the extent of ablation, if required, are critical. The laser thermal mechanism of injury is intricately related to the selective absorption of light and its exposure duration, similarly to the laser induced ablation. The laser ablation mechanisms were categorized into four different categories (the photo-thermally induced ablation, the photo-mechanically induced ablation, the plasma induced ablation and the photoablation) and their fundamentals are herein described. The brief history of laser treatment modality in dermatology and urology are summarized.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.55-60
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• 1999

To investigate analgesic mechanism of capsaicin and its analogues (capaicinoids) adenosine release was measured by high performance liquid chromatography from rat spinal cord synaptosomes. Exposure of synaptosomes to $K^+$ and morphine produced a dose dependent release of adenosine in the presence of $Ca^{++}$. Capsaicin (0.1, 1, $10{\;}{\mu}M$), and its analogues: NE-19550 (1, 10, $100{\;}{\mu}M$), DMNE (1, 10, $100{\;}{\mu}M$) and KR 25018 (0.1, 1, $10{\;}{\mu}M$) produced a concentration dependent release of adenosine in the presence of $Ca^{++}$. Nifedifine, L-type voltage sensitive calcium channel blocker, inhibited $K^+$ (6, 12 mM)-and morphine ($10{\;}{\mu}M$)-evoked release of adenosine partially. Capsazepine, a novel capsaicin selective antagonist, blocked only capsaicin and capsaicinoids induced release of adenoside. Therefore, it is suggested that the adenosine release by capsaicin and capsaicinoids having antinociceptive effects involves actvation of capsaicin specific receptor and capsaicin sensitive $Ca^{++}$. channel.