• Applied Microscopy
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• v.22 no.2
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• pp.30-45
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• 1992

An experimental study on the acute irradiation effects on the substantia nigra of head-irradiated rats were carried out. Rats anesthetized with sodium thiopental, were exposed only on their head areas with a single dose of 3,000 rads or 6,000 rads, respectively. Radiation was produced by Mitsubishi linear accelerator at the speed of 200 rads/min. Aminals were sacrificed on 6 hours, 2 days and 6 days following irradiations. By the perfusion fixation through the heart, rats were fixed with 1% glutaraldehyde-1% paraformaldehyde solution. Two hours later, brains were exposed and immersed in the same fixatives over night. Tissue blocks from subtantia nigra were punched out, and they were refixed in the 2% osmium tetroxide solution. Blocks were dehydrated through alcohol series, and embedded in the araldite mixture. Ultrathin sections were stained with uranyl acetate and lead citrate solutions, From the ultrastructural study, following results were made: 1. Six hours after irradiation, severe depletion of synaptic vesicles was occurred in the many axon terminals of the nigral neuropil. 2. Dramatical decrease of lysosomes and dense granules was observed. 3. Two days following irradiation, alterations of ribosomes, granular endoplasmic reticula, mitochondria, etc, were noticed. 4. Many of the malformations were seen to be repaired on the 6th day. 5. Above results were interpreted as follows. At the acute stage of heavy irradiation, neurotransmitters in the substantia nigra are released severely. But they are recovered within 6 days. It is concluded that acute head-irradiation may result severe disturbance of nigral motor control function during the first few days.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.171-191
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• 1998

The present study was designed to elucidate the effects of the Co-60 γ irradiation and/or calcium-deficient diet on the periodontal tissue formation in rat pups. The pregnant three-week old Sprague-Dawley rats were used for the study. The experimental group was divided into two groups, irradiation/normal diet group (Group 2) and irradiation/calcium-deficient diet group (Group 3). The control group was non-irradiation/normal diet group (Group 1). The abdomen of the rats at the 19th day of pregnancy were irradiated with single absorbed dose of 350 cGy. The rat pups were sacrificed on the 14th day after delivery, and the maxillae including molar tooth germ were taken. The specimens including the 1st molar tooth germ were prepared to make tissue sections for light and transmission electron microscopy. Some of tissue sections for light microscopy were stained immunohistochemically with anti-fibronectin and anti-osteonectin antibodies. The results were as follows; 1. In the periodontal ligament forming area, the fibroblasts of Group Z showed irregular arrangement and low activity. The immunoreactivity between the fibroblasts and collagen fibers was decreased, compared with Group 1. The fibroblasts of Group 3 showed atrophic change and clumped nucleus. The collagen fibers showed cystic change and low immunoreactivity to the fibronectin. 2. In the cementum forming area, the cementoblasts of Group 2 showed decrease of number and atrophic change. The cementoblasts of Group 3 showed edematous change, atrophy of cytoplasm, and clumping of nucleus. 3. In the alveolar bone forming area, the bone of Group 2 was thin and various degree of immunoreactivity to the osteonectin. Group 3 showed edematous osteoblasts, fibrous degeneration of bone marrow, and weak immunoreactivity to the osteonectin.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.175-178
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• 2011

This study was conducted with effect of lactic acid bacteria by gamma irradiation. Lactic acid bacteria were exposed to irradiation with a single absorbed dose of 1, 2, 3, 4, 5, 6, 8, and 10 kGy. Possible lactic acid bacteria, including Lactobacillus paracasei KCTC 13169, Lactobacillus casei KCTC 3109, Lactobacillus acidophilus KCTC 3140, Lactobacillus plantarum subsp plantarum KCTC 3103, Lactobacillus debruekii subsp bulgaricus KCTC 3635, Streptococcus thermophilus KCTC 3658 were selected. The radiation sesitivities of lactic acid bacteria were expressed as $D_{10}$ values. The $D_{10}$ values of Lactobacillus paracasei, Lactobacillus casei, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus debruekii were calculated as 0.42, 0.51, 0.47, 0.90, 0.44, and 0.61 kGy, respectively. Results suggest that L. acidiphilus has the highly resistant to gamma irradiation.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.85-98
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• 1991

The aim of this study was to investigate the effect of low - power laser used in the medical field for various purposes to suppress pain responses evoked by noxious electrical or mechanical stimuli. After both inferior alveolar nerves and the left anterior digastric muscle of cats under general anesthesia were exposed, a recording electrode for the jaw opening reflex was inserted into the anterior digastric muscle. The right inferior alveolar nerve was dissected under a surgical microscope until the response of the functional single nerve could be evoked by the electrical stimulation of the dental pulp or oral mucosa. The electrical stimulus was applied with a rectangular pulse of 10 ms duration for measuring the threshold intensity of a single nerve fiber in the inferior alveolar nerve which responds to stimulation of dental pulp and oral mucosa. Then a pulse of 1 ms duration was applied for determination of conduction velocity. A noxious mechanical stimulus to the oral mucosa was applied by clamping the receptive field with an arterial clamp. The Ga-As diodide laser(wave length, 904 nm ; frequency, 1,000 Hz) was irradiated to the prepared tooth cavity, inferior alveolar nerve and oral mucosa as a pulse wave of 2 mW for 6 minutes. This was followed by a continuous wave of 15 mW for 3 minutes. The action potential of the nerve and EMG of the digastric muscle evoked by the noxious electrical stimulus and nerve response to noxious mechanical stimulus were compared at intervals of before, immediately after, and at 5, 10, 20, 40, 60 minutes after laser irradiation. The results were as follows: The conduction velocity of the intrapulpal $A{\delta}$- nerve fiber recorded from the inferior alveolar nerve before irradiation had a mean value of $6.68{\pm}2.07m/sec$. The laser irradiation did not affect the conduction velocity of the AS - nerve fiber and did not change the threshold intensity or amplitude of the action potential either. The EMG of the digastric muscle evoked by noxious electrical stimulation to the tooth was not changed by the laser irradiation, whether in latency, threshold intensity or amplitude. The laser irradiated to the receptive field of the oral mucosa which was subjected to noxious stimuli did not affect the amplitude of the action potential or the frequency either.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.53-59
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• 2008

We observed DNA damages as a function of mean absorbed dose to identify the indirect effect of high-energy radiation such as x-ray. Monolayer films of lyophilized pGEM-3Zf(-) plasmid DNA deposited on tantalum foils were exposed to Al $K{\alpha}$ X-ray (1.5 keV) for 0, 3, 7 and 10 min, respectively, in a condition of ultrahigh vacuum state. We compared DNA damages by X-ray irradiation with those by 3 eV electron irradiation. X-ray photons produced low-energy electrons (mainly below 20 eV) from the tantalum foils and DNA damage was induced chiefly by these electrons. For electron beam irradiation, DNA damage was directly caused by 3 eV electrons. Irradiated DNA was analyzed by agarose gel electrophoresis and quantified by ImagaQuant program. The quantities of remained supercoiled DNA after irradiation were linearly decreased as a function of mean absorbed dose. On the other hand, the yields of nicked circular (single strand break, SSB) and interduplex crosslinked form 1 DNA were linearly increased as a function of mean absorbed dose. From this study, it was confirmed that DNA damage was also induced by low energy electrons ($0{\sim}10\;eV$) even below threshold energies for the ionization of DNA.

• Journal of Life Science
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• v.17 no.12
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• pp.1654-1659
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• 2007

We examined total body irradiation (TBI)-induced effects by complete blood count (CBC) and fluorescence-activated cell sorter analysis (FACS) in the piglet following radiation irritation. A CBC included red blood cell count, white blood cell count, and platelet cell count. Four piglets were examined in this study and each piglet was divided by irradiation dose, two piglets with 4 Gy, two with 6 Gy, one with 8 Gy. All piglets showed leukopenia, thrombocytopenia after irradiation. In 6 and 8 Gy group, three piglets showed severe hemostatic disorder and gastrointestinal disorder suchas diarrhea and anorexia, and they died between 10 and 15 days after radiation irritation. In 4 Gy, two piglets showed no clinical sign after radiation injury, but persistent leukopenia was shown in blood examination. We suggest that a single TBI dose less than 6 Gy is adequate for conditioning piglet for bone marrow transplantation.

• Journal of Radiation Protection and Research
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• v.12 no.2
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• pp.1-8
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• 1987

The relative biological effectiveness has been measured for the biological characterization of $p^+(50.5\;MeV)$ Be neutron of KCCH-Cyclotron prior to clinical application. Measured RBE of mouse jejunal crypt cell in single whole body irradiation was 2.8. This RBE value is changed differently in different biologic systems such as mouse jejunal crypt cells, intestine and bone marrow in different irradiation method, so that in fractionated irradiation RBE is variable to the different fraction size and total dose, and also variable to the number of fractions.

• Journal of Ginseng Research
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• v.36 no.3
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• pp.308-313
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• 2012

Fresh (raw roots), white (dried), and red (steamed-drid) ginseng samples were gamma-irradiated at 0 to 7 kGy. Electron spin resonance (ESR) technique was used to characterize the irradiation status of the samples, targeting the radiation-induced cellulose radicals after different sample pretreatments. All non-irradiated samples exhibited a single central signal (g=2.006), whose intensity showed significant increase upon irradiation. The ESR spectra from the radiation-induced cellulose radicals, with two side peaks (g=2.0201 and g=1.9851) equally spaced (${\pm}3mT$) from the central signal, were also observed in the irradiated samples. The core sample analyzed after alcoholic-extraction produced the best results for irradiated fresh ginseng samples. In the case of irradiated white and red ginseng samples, the central (natural) and radiation-induced (two-side peaks corresponding to cellulose radical) signal intensities showed little improvement on alcoholic-extraction. The water-washing step minimized the effect of $Mn^{2+}$, but reduced the intensity of side peaks making them difficult to indentify. The effect of different origins was negligible, however harvesting year showed a clear effect on radiation-induced ESR signals.

• Radiation Oncology Journal
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• v.37 no.1
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• pp.1-12
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• 2019

Despite recent innovation in treatment techniques and subsequently improved outcomes, the majority of glioblastoma (GBL) have relapses, especially in locoregional areas. Local re-irradiation (re-RT) has been established as a feasible option for recurrent GBL of all ages with safety, tolerability, and effectiveness both in survival and quality of life regardless of fractionation schedule. To keep adverse effects under acceptable range, cumulative dose limit in equivalent dose at 2 Gy fractions by the linear-quadratic model at α/β = 2 for normal brain tissue (EQD2) with narrow margin should be observed and single/hypofractionated re-RT should be undertaken very carefully to recurrent tumor with large volume or adjacent to the brainstem. Promising outcome of re-operation (re-Op) plus re-RT (re-Op/RT) need to be validated and result from re-RT with temozolomide/bevacizumab (TMZ/BV) or new strategy is expected. Development of new-concept prognostic scoring or risk group is required to select patients properly and make use of predictive biomarkers such as O(6)-methylguanine-DNA methyltransferase (MGMT) promotor methylation that influence outcomes of re-RT, re-Op/RT, or re-RT with TMZ/BV.

• Journal of Adhesion and Interface
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• v.6 no.4
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• pp.12-17
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• 2005

Natural fiber/phenolic biocomposites with chopped henequen fibers treated at various levels of electron beam irradiation (EBI) were made by means of a matched-die compression molding method. The interfacial property was explored in terms of interfacial shear strength measured by a single fiber microbonding test. The thermal properties were studied in terms of storage modulus, tan ${\delta}$, thermal expansion and thermal stability measured by dynamic mechanical analysis, thermomechanical analysis and thermogravimetric analysis, respectively. The result showed that the interfacial and thermal properties depend on the treatment level of EBI done to the henequen fiber surfaces. The present result also demonstrates that 10 kGy EBI is most preferable to physically modify the henequen fiber surfaces and then to improve the interfacial property of the biocomposite, supporting earlier results studied with henequen/poly (butylene succinate) and henequen/unsaturated polyester biocomposites.