• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.121-132
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• 2002

Purpose : Taxol(Paclitaxel), an antineoplastic agent, has been used in the treatment of ovarian and breast cancers. The determination of optimal Taxol concentrations in human serum was required for enhancing therapeutic effect and maintaining the appropriate Taxol level in blood. This study was aimed to synthesizeradiolabeled Taxol derivatives as radiotracer in competitive radioimmunoassay for monitoring Taxol concentrations in blood and to determine the usefulness of its derivatives. Materials and Methods : Hemisucdcinyltaxol(HT) was synthesized by esterification of Taxol with succinic anhydride. Tyraminehemisuccinyltaxol(THT) was synthesized by coupling of HT with tyramine using isobutylchlormate as coupling agent and purified by HPLC. By using chloramine-T($5.25mg/ml,\;10{\mu}{\ell}$) as oxidant agent, THT($4mg/ml,\;30{\mu}{\ell}$) was labeled wity $^{125}I\;(37MBq,\;1mCi)$. To estimate the stability of purified THT, $^{125}I-iodotyraminehemisuccinyltaxol(^125}ITHT)$ was dissolved in 80% acetonitrile aqueous solution, and the solution was incubated at $4^{\circ}C\;and\;37^{\circ}C$ for 7 days. At various time intervals, the stability of THT and $^{125}ITHT$ was monitored. The titer of Taxol monoclonal antibody, 3G5A7, was determined by competitive radioimmunoassay using $^{125}ITHT$ as a labeled antigen. A standard dose-response curve was demonstated by Taxol competitive radioimmunoassay. Resulls : HT and THT were synthesized with 79.9% and 19.5% yield, respectively. The labeling yield of $^{125}ITHT$ was 93%. After 7 days, the chemical purity of THT was 96.5% at $4^{\circ}C$, and 97.5% at $37^{\circ}C$. After 3 days, $^{125}ITHT$ was stable with 94.7% at $4^{\circ}C$ and 93.4% at $37^{\circ}C$. After 7 days, fadiochemical purity was diminished to 88.1% at $37^{\circ}C$. The titer of Taxol monoclonal antibody, 3G5A7, was determined to 1:256. A standard dose-response curve demonstated good collinearity ($R^2=0.971$) as Taxol concentration-dependent manner. Conclusion : Competitive radioimmunoassay using $^{125}I-iodotyraminehemisuccinytaxol$ as radiotracer could be used to monitor for concentration of Taxol in the human serum.

• Progress in Medical Physics
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• v.25 no.3
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• pp.157-166
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• 2014

ATP in quantity co-stored with neurotransmitters in the secretory vesicles of neurons, by being co-released with the neurotransmitters, takes an important role to modulate the stimulus-secretion response of neurotransmitters. Here, in this study, the modulatory effect of ATP was studied in $Ca^{2+}$ channels of cultured rat adrenal chromaffin cells to investigate the physiological role of ATP in neurons. The $Ca^{2+}$ channel current was recorded in a whole-cell patch clamp configuration, which was modulated by ATP. In 10 mM $Ba^{2+}$ bath solution, ATP treatment (0.1 mM) decreased the $Ba^{2+}$ current by an average of $36{\pm}6%$ (n=8), showing a dose-dependency within the range of $10^{-4}{\sim}10^{-1}mM$. The current was recovered by ATP washout, demonstrating its reversible pattern. This current blockade effect of ATP was disinhibited by a large prepulse up to +80 mV, since the $Ba^{2+}$ current increment was larger when treated with ATP ($37{\pm}5%$, n=11) compared to the control ($25{\pm}3%$, n=12, without ATP). The $Ba^{2+}$ current was recorded with $GTP{\gamma}S$, the non-hydrolyzable GTP analogue, to determine if the blocking effect of ATP was mediated by G-protein. The $Ba^{2+}$ current decreased down to 45% of control with $GTP{\gamma}S$. With a large prepulse (+80 mV), the current increment was $34{\pm}4%$ (n=19), which $25{\pm}3%$ (n=12) under control condition (without $GTP{\gamma}S$). The $Ba^{2+}$ current waveform was well fitted to a single-exponential curve for the control, while a double-exponential curve best fitted the current signal with ATP or $GTP{\gamma}S$. In other words, a slow activation component appeared with ATP or $GTP{\gamma}S$, which suggested that both ATP and $GTP{\gamma}S$ caused slower activation of $Ca^{2+}$ channels via the same mechanism. The results suggest that ATP may block the $Ca^{2+}$ channels by G-protein and this $Ca^{2+}$ channel blocking effect of ATP is important in autocrine (or paracrine) inhibition of adrenaline secretion in chromaffin cell.

• The Journal of Internal Korean Medicine
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• v.21 no.3
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• pp.377-388
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• 2000

Objective : This study was undertaken to evaluate the effect of Sunghyangchungisan (SHCS) on the regulation of vascular tone and $Ca^{2+}$ metabolism in arterial tissues. Vascular rings isolated from rabbit carotid artery were myographed isometrically in isolated organ baths and the effect of SHCS on contractile activities, endothelial function and $Ca^{2+}$ metabolism were determined. Methods : In phentobarbital sodium-anesthetized rabbits, SHCS administered through ear vein (100 mg/Kg body wt.) or intragastric dwelling tube (300 mg/Kg body wt.) attenuated phenylephrine (PE, 10 ${\mu}g$/Kg, i.v.)-induced increases in both systolic and diastolic cartoid arterial blood pressure. Results : In experiments with isolated arterial strips, SHCS relaxed arterial rings which were pre-contracted by phenylephrine (PE, 1 ${\mu}M$). The responses to SHCS were partially dose-dependent at concentrations lower than 0.5 mg/ml. When SHCS was applied prior to the exposure to PE, it inhibited the PE-induced contraction by a similar magnitude which was comparable to the relaxation of pre-contracted arterial rings. Washout of SHCS after observing its relaxant effect resulted in a full recovery of PE-induced contractions, indicating that the action mechanism is reversible. The observation that SHCS did not change the $ED_{50)$ of PE oh its dose-response curve ruled out the possible interaction of SHCS with ${\alpha}$-receptors. The relaxant effect of SHCS was not affected by removal of endothelium or a nitric oxide synthase inhibitor, L-NAME. Methylene blue, an inhibitor of the soluble guanylate cyclase, did not affect the relaxant effect of SHCS. These results suggest that the action of SHCS is not mediated by the endothelium nor soluble guanylate cyclase. Constant cGMP production determined in arterial strips in the presence or absence of SHCS is consistent with this conclusion. When contraction was induced by additive application of $Ca^{2+}$ in arterial rings which were pre-depolarized by high $K^+$ in a $Ca^{2+}$-free solution, the relaxant effect of SHCS was attenuated by increasing the $Ca^{2+}$ concentration. SHCS, when applied to the arterial rings pre-contracted by PE and then relaxed by nifedipine, a $Ca^{2+}$ channel blocker, did not show additive relaxation. SHCS partially blocked $Ca^{2+}$ influx stimulated by PE and high $K^+$ which was determined by 5-min ^{45}Ca$ uptake, while it did not affect $Ca^{2+}$ efflux. Conclusions : From above results, it is suggested that SHCS relax PE-induced contraction of rabbit carotid artery in an endothelium independent manner, andinhibition of $Ca^{2+}$ influx may contribute to the underling mechanism.

• Journal of Ginseng Research
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• v.42 no.2
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• pp.183-191
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• 2018

Background: Ginseng saponin has long been used as a traditional Asian medicine and is known to be effective in treating various kinds of pain. Ginsenoside Rf is one of the biologically active saponins found in ginseng. We evaluated ginsenoside Rf's antinociceptive and anti-inflammatory effects, and its mechanism of action on adrenergic and serotonergic receptors, in an incisional pain model. Methods: Mechanical hyperalgesia was induced via plantar incision in rats followed by intraperitoneal administration of increasing doses of ginsenoside Rf (vehicle, 0.5 mg/kg, 1 mg/kg, 1.5 mg/kg, and 2 mg/kg). The antinociceptive effect was also compared in a Positive Control Group that received a ketorolac (30 mg/kg) injection, and the $Na{\ddot{i}}ve$ Group, which did not undergo incision. To evaluate the mechanism of action, rats were treated with prazosin (1 mg/kg), yohimbine (2 mg/kg), or ketanserin (1 mg/kg) prior to receiving ginsenoside Rf (1.5 mg/kg). The mechanical withdrawal threshold was measured using von Frey filaments at various time points before and after ginsenoside Rf administration. To evaluate the anti-inflammatory effect, serum interleukin $(IL)-1{\beta}$, IL-6, and tumor necrotizing $factor-{\alpha}$ levels were measured. Results: Ginsenoside Rf increased the mechanical withdrawal threshold significantly, with a curvilinear dose-response curve peaking at 1.5 mg/kg. $IL-1{\beta}$, IL-6, and tumor necrotizing $factor-{\alpha}$ levels significantly decreased after ginsenoside Rf treatment. Ginsenoside Rf's antinociceptive effect was reduced by yohimbine, but potentiated by prazosin and ketanserin. Conclusion: Intraperitoneal ginsenoside Rf has an antinociceptive effect peaking at a dose of 1.5 mg/kg. Anti-inflammatory effects were also detected.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1114-1119
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• 2012

This study was conducted to assess the microbial toxicity of ionic silver solution ($Ag^+N$) and silver nanoparticle suspension ($Ag^0NP$) based on the Microtox bioassay. In this test, the light inhibition of luminescent bacteria was measured after 15 and 30 min exposure to aqueous solutions and soils spiked with a dilution series of $Ag^+N$ and $Ag^0NP$. The resulting dose-response curves were used to derive effective concentration (EC25, $EC_{50}$, EC75) and effective dose ($ED_{25}$, $ED_{50}$, $ED_{75}$) that caused a 25, 50 and 75% inhibition of luminescence. In aqueous solutions, $EC_{50}$ value of $Ag^+N$ after 15 min exposure was determined to be < $2mg\;L^{-1}$ and remarkably lower than $EC_{50}$ value of $Ag^0NP$ with $251mg\;L^{-1}$. This revealed that $Ag^+N$ was more toxic to luminescent bacteria than $Ag^0NP$. In soil extracts, however, $ED_{50}$ value of $Ag^+N$ with 196 mg kg-1 was higher than $ED_{50}$ value of $Ag^0NP$ with $104mg\;kg^{-1}$, indicating less toxicity of $Ag^+N$ in soils. The reduced toxicity of $Ag^+N$ in soils can be attributed to a partial adsorption of ionic $Ag^+$ on soil colloids and humic acid as well as a partial formation of insoluble AgCl with NaCl of Microtox diluent. This resulted in lower concentration of active Ag in soil extracts obtained after 1 hour shaking with $Ag^+N$ than that spiked with $Ag^0NP$. With longer exposure time, EC and ED values of both $Ag^+N$ and $Ag^0NP$ decreased, so their toxicity increased. The toxic characteristics of silver nanomaterials were different depending on existing form of Ag ($Ag^+$, $Ag^0$), reaction medium (aqueous solution, soil), and exposure time.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.921-925
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• 2003

To control blood glucose level as close to normal is the major goal of treatment of diabetes mellitus. $\alpha$-glucosidase is the enzyme to digest dietary carbohydrate and inhibition of $\alpha$-glucosidase could suppress postprandial hyperglycemia. The methanol extract of soybean sprout was tested for the inhibitory activities against $\alpha$-glucosidase in vitro. Soybean sprout extract inhibited yeast $\alpha$-glucosidase activity by 24.5% at the concentration of 5 mg/mL. The methanol extract of soybean sprout was subsequently subjected to sequential fractionation with hexane, ethyl acetate, butanol and water. Among the fractions tested ethyl acetate-soluble fraction showed relatively strong inhibition against $\alpha$-glucosidase by 36.3% at the concentration of 5 mg/mL. Acarbose, standard $\alpha$-glucosidase inhibitor, inhibited $\alpha$-glucosidase activity by 40.1%. The ability of soybean sprout extract to lower postprandial glucose was studied in streptozotocin-induced diabetic rats. Starch solution (1 g/kg) with and without the methanol extract of soybean sprout (500 mg/kg) was administered to diabetic rats after an overnight-fast by gastric intubation. A single oral dose of soybean sprout extract inhibited the increase in blood glucose levels significantly at 60, 90, 120, 180 min (p<0.05) and decreased incremental response areas under the glycemic response curve significantly (p<0.05). These results suggest that soybean sprout might exert hypoglycemic effect by inhibiting $\alpha$-glucosidase activity.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.505-515
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• 1998

Purpose : This study is intended to understand the sensitometric characteristics and the emulsion properties of the commercially available CEA TVS film in comparison with the Kodak X-Omat V film. Materials and Methods : For this purpose, we have formulated an analytic expression of the characteristic curves for x-ray film exposed to mixed radiation of electrons, photons, and visible light. This mathematical expression was developed based on reaction-rate and target-hit theories. Unlike previous expressions. it relates optical density to emulsion properties such as grain size and silver bromide content We have also developed a quantity which characterizes the film response to visible light relative to that to photons and electrons. This quantity could be expressed as a function of grain area. Thus, we have developed mathematical expressions and quantities with which the emulsion properties of the films can be revealed based on the sensitometric characteristics. Demonstrating the use of this analytical study, we exposed CEA and Kodak verification films to the mixed radiation of electrons, photons, and visible light, and interpreted the experimental results accordingly. Results : We have demonstrated that: (1) the saturation density increases as the silver bromide content increases, (2) the time required to reach the threshold dose (to which the film begins to respond) when films are exposed to visible light decreases as the grain size increases, and (3) the CEA film contains more silver bromide. whereas the Kodak film contains larger grains. These findings were supported by the data provided by the manufacturers afterward. Conclusion : This study presented an analytical and experimental basis for understanding the response of X-ray film with respect to the emulsion properties.

• The Korean Journal of Pharmacology
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• v.28 no.2
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• pp.129-136
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• 1992

As it has been reported that the depolarization-induced acetylcholine (ACh) release is modulated by activation of presynaptic $A_1-adenosine$ heteroreceptor in hippocampus and various lines of evidence indicate the involvement of adenylate cyclase system in $A_1-adenosine$ post-receptor mechanism in hippocampus, it was attempted to delineate the role of adenylate cyclase system in the $A_1-receptor-mediated$ control of ACh release in this study. Slices from rat hippocampus were incubated with $[^3H]-choline$ and the release of the labelled products was evoked by electrical stimulation $(3\;Hz,\;5\;Vcm^{-1},\;2\;ms,\;rectangular\;pulses)$, and the influence of various agents on the evoked tritium-outflow was investigated. $N^6-cyclopentyladenosine$ (CPA), a specific $A_1-adenosine$ receptor agonist, in concentrations ranging from 0.1 to $10\;{\mu}M$, decreased the $[^3H]-ACh$ release in a dose-dependent manner without the changes of basal rate of release. 8-cyclopentyl-1,3-dipropylxanthine $(DPCPX,\;1{\sim}10\;{\mu}M)$, a selective $A_1-receptor$ antagonist, increased the $[^3H]-ACh$ release in a dose-related fashion with slight increase of basal tritium-release. And the CPA effects were significantly inhibited by DPCPX $(2\;{\mu}M)$ pretreatment and the dose-response curve produced by CPA was shifted to the right. The responses to N-ethylmaleimide $(NEM,\;10\;&\;30\;{\mu}M)$, a SH-alkylating agent of G-protein, were characterized by increments of the evoked ACh-release and the basal release, and the CPA effect were completely abolished by NEM pretreatment. Forskolin, a specific adenylate cyclase activator, in concentrations ranging from 0.3 to $10\;{\mu}M$, increased the evoked ACh-release in a dose-dependent manner and the CPA effects were inhibited by forskolin. These results indicate that the $A_1-adenosine$ heteroreceptor plays an important role in ACh-release via nucleotide-binding protein Gi in the rat hippocampus and that the adenylate cyclase system might be participated in this process.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.194-201
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• 2015

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.