• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.717-721
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• 2002

Study was carried out with electron spin resonance (ESR) spectroscopy to identify irradiated Korean medicinal herbs. Pueraria thunbergiana Benth., Angelica gigas Nakai, Agaricus blazei Murill and Astragalus membranaceus Bunge were irradiated with doses of 0, 1, 5 and 10 kGy at room temperature using a Co-60 irradiator. The irradiated Korean medicinal herbs exhibited an asymmetric absorption, which was different from the non-irradiated ones. The strength of ESR signals linearly increased by dose-dependent manner (1~10 kGy) and highly positive correlation coefficients ($R^2$=0.9428~0.9942) were obtained between the irradiation doses and the corresponding ESR signal intensities. Detection of the irradiated Korean medicinal herbs was possible even after 6 weeks of storage although the signal intensities of the irradiated samples decreased until 2 weeks at room temperature.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.665-671
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• 1999

Post mortem bovine muscle. semitendinosus was used to investigate the effects of gamma irradiation on physicochemical properties. The muscle was cut into pieces of 2 cm in thickness and packaged with 2 different methods; vacuum-packaged and air-packaged. The packaged samples were irradiated at designated doses of 0, 1, 3 and 5 kGy by Cobalt-60 irradiator. Muscle protein solubility, purge loss, composition and contents of free amino acids, and shear force were observed during storage at $4^{\circ}C$. We found no significant differences in the purge loss and the contents of free amino acids. Muscle protein solubility slightly increased depending upon the increase of the dose. The decrease of shear force by gamma irradiation was observed. Therefore, it is considered that meat quality can be improved by gamma irradiation.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1060-1063
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• 2003

Electron spin resonance (ESR) spectroscopy was used to investigate the effects of irradiation doses and storage times on three spices. Three imported spices (Brassica juncea, Origanum vulgare, Laurus nobilis) were irradiated with doss of 0, 1, 5 and 10 kGy using a Co-60 irradiator at room temperature. ESR signals were measured from each sample by a Bruker-EPR spectrometer. The gamma-irradiated Brassica and Laurus nobilis exhibited characteristic signals, which were different from those of the non-irradiated ones. Non-irradiated and irradiated Origanum vulgare exhibited single lines, with higher ESR signals in irradiated sample than in non-irradiated sample. The ESR signals increased linearly with increasing irradiation doses $(1{\sim}10kGy)$. A strong positive correlation coefficient $(R^2=0.9939{\sim}0.9993)$ was obtained between the irradiation doses and the corresponding ESR signal intensities. Although the ESR signal intensities decreased with storage time, signals from the three irradiated spices were observed even after 12 weeks of storage at room temperature.

• Journal of Food Hygiene and Safety
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• v.15 no.1
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• pp.1-4
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• 2000

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose on the ESR signal intensity of irradiated crabs and the stability of these radicals under 9 weeks of storage. Swimming and small crabs were irradiated with doses of 0, 1, 3, 5 and 7 kGy using a Co-60 irradiator at ambient temperature. A claw, a walking leg and a cars- pace of the crab pieced and dried were placed in a resonant quart tube within an EPR X-band spectrometer. The irradiated crabs presented an asymmetric absorption in shape at g$_1$=2.002 $\pm$ 0.003 and g$_2$=1.998$\pm$0.005, and were different from the non-irradiated ones. The intensity of the ESR signals was greatest in the claw, intermediate in the carapace and lowest in the walking leg. Samples given low and high doses of irradiation could also be distinguished. The ESR signal after irradiation was stable, even after a 9-week storage.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.170-173
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• 2002

Electron spin resonance (ESR) spectroscopy was used to detect free radicals in irradiated wheat flour and glutinous rice flour. They were irradiated with doses of 0, 0.1, 0.5, 1 and 2 kGy at room temperature using a Co-60 irradiator. Free radicals detected for irradiated wheat flour and glutinous rice flour were higher than those of unirradiated ones. Since concentration of free radicals linearly increased with applied doses $(0.1{\sim}2\;kGy)$, highly positive correlation coefficients $(R^2=0.9995{\sim}0.9998)$ were obtained between irradiation doses and free radical concentrations right after irradiation. Although concentration of free radicals slowly decreased with storage time, the characteristic ESR signals of free radical in irradiated samples were observed even after 4 weeks of storage at room temperature.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.327-339
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• 1999

Objectives: The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. Material and Methods: Human epidermoid carcinoma A-431 cell lines were irradiated by 2, 4, 6, 8, 10Gy at a dose rate of 210cGy/min using /sup 60/Co Irradiator ALDORADO 8 and then were exposed to bleomycin or cisplatin at concentration of 2㎍/㎖ for 1 hour. The viable cells were determined for each radiation dose and/or each drug at the 4th day and cell surviving curves were obtained using semiautomated MTT assay. Results: The surviving fraction after irradiation of 2Gy was 0.99, and there was not significant difference of surviving fraction in comparison with the control group on A-431 cell line(P>0.05). But there were significant differences of surviving fractions at doses of 4, 6, 8, 10Gy in comparison with the control group(P<0.05). The cytotoxicity of bleomycin or cisplatin was significantly different in comparison with the control group on A-43l cell line (P<0.05). And the cytotoxicity of cisplatin was greater than that of bleomycin on A-431 cell line (P<0.05). There were significant differences of surviving fractions after irradiation of 2, 4, 6, 8, 10Gy with bleomycin or cisplatin in comparison with each group of irradiation only on A-431 cellline(P<0.05). There were significant differences of surviving fractions between the groups of irradiation with bleomycin and cisplatin at doses of 2, 4Gy(P<0.05), but there were not significant differences of surviving fractions at doses of 6, 8, 10Gy on A-431 cell line (P>0.05).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.483-499
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• 1995

Mandibular first molars of the rats were undertaken to observe the radiosensitivity of amelogenesis. Twenty four Sprague-Dawley rats received 396cGy radiation with the MK Cell irradiator using Cs-137, and twenty four rats served as control. They were devided into two groups; Group 1 which received radiation at the 14th day after gestation and group 2 which received radiation at the 19th day after gestation. Light Microscopy and Transmitted Electron Microscopy investigation was undertaken in the group 1 at the 15th, 18th, 20th, 22nd(2 days after birth), and 25th day(5 days after birth) after gestation, and in the group 2 at the 21th(birth day), 22nd(2 days after birth), and 25th(5 days after birth) day after gestation. The following histopathologic findings were obtained. 1. Compared with control group, experimental group showed a delayed formation of enamel and dentin due to slow rate of differentiation of undifferentiated mesenchymal cells. 2. In the experimental groups, the arrangement of the inner enamel epithelium was irregular and there were many vacuoles in the cytoplasm. There were dilated rER and mitochondria, increase of the intercellular space, and loss of the cellular polarity. 3. In the group 1, early enamel without Tomes' process, and early organic matrix was observed at the 25th day after gestation. 4. In the group 2, histopathologic changes were similar to those of the group 1, but the degree of changes was more severe than that of the group 1.

• Imaging Science in Dentistry
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• v.33 no.1
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• pp.51-57
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• 2003

Purpose: To investigate the effects of irradiation on the phenotypic expression of the MC3T3-El osteoblastic cell line, particularly an the expression of type I collagen and alkaline phosphatase mRNA. Materials and Methods: Cells were irradiated with a single dose of 0.5, 1, 2, 4, and 8 Gy at a dose rate of 5.38 Gy/min using a cesium 137 irradiator. The specimens were then harvested and RNA extraction was carried out at 1 and 3 days after irradiation. The extracted RNA strands were reverse-transcribed and the resulting cDNA fragments were amplified by PCR. Results: The irradiated cells demonstrated a dose-dependent increase in type I collagen mRNA expression relative to the control group, with a maximum level of type I collagen mRNA expression occurring at 8 Gy. The degree of type I collagen mRNA expression increased significantly at 1 day after irradiation, but little differences were found between the control group and at the 3rd day. The amount of alkaline phosphatase mRNA expression increased significantly at land 3 days after irradiation in the 1 Gy exposed group compared with the control group. Conclusion: The amount of type I collagen and alkaline phosphatase mRNA expression increased significantly 1 day after irradiation when compared with the control group.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.57-61
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• 2002

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose and storage time on the free radical concentrations in gamma-irradiated dried seasoning powder. Seasoning powders of dried squid flavor, shrimp flavors, kimchi flavor, spicy beef soup flavor and soy sauce flavor were irradiated with doses of 0, 1, 3, 5, 7 and 9 kGy at room temperature using a Co-60 irradiator. Characteristic signals of free radicals were observed in all the irradiated samples of this experimental while these signals were not detected in non-irradiated samples. Since the free radical concentrations linearly increased with the applied doses (1~9 kGy), highly positive correlation coefficients ($R^2$ = 0.9285~0.9965) were obtained between irradiation doses and free radical concentrations during all the storage times. Free radical concentrations of the irradiated flavored seasoning powder did not change even at 16 weeks of storage at room temperature, while those of dried squid, shrimp and spicy beef soup flavors decreased until 2 weeks of storage after irradiation with 5 kGy or over, and these of soy cause flavors slowly decreased until 8 weeks of storage after irradiation with 3 kGy or over. Although the free radical concentrations decreased with storage times, the characteristic signals of the irradiated seasoning powders of dried squid, shrimp, spicy beef and soy sauce flavors were observed even after 16 weeks of storage at room temperature.

• Progress in Medical Physics
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• v.23 no.4
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• pp.229-233
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• 2012

A small water phantom (dual-window phantom) was developed to improve the output measurement efficiency of medical linacs. This phantom is suitable for determining the quality index and output dose for high-energy photon beams. The phantom has two opposite windows and two independently rotating axes. The two axes measure the tissue phantom ratio (TPR) and the percentage depth dose (PDD) simply without requiring chamber movement by rotating the phantom around its axis. High-energy photon beams from a Co-60 irradiator and a medical linac were used to evaluate the phantom. The measured quality index is in good agreement with the reference values; the measured and reference values are within 0.2% of each other for the Co-60 gamma rays and within 1.4% for 6 and 10 MV X-rays. This phantom is more practical for routine output measurements, resulting in the prevention of potential human errors.