• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.517-525
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• 1993

Glutathione(GSH),a tripeptide thiol, found in virtually all cells, functions in metabolism tranasport and cellular protection. It protects cells against the destructive effects of reactive oxygen intermediates and free radicals. Also ${\gamma}-Glutamyl$ transpeptidase(${\gamma}-GTT$), an enzyme of major importance in GSH metabolism, initiates GSH degradation. In order to explore the $GSH-{\gamma}-GTT$ system as periodontal disease activity indicator, we observed the ${\gamma}-GTT$ and arachidonic acid metabolits according to clinical groups(Control, Adult periodontitis, Rapidly progressive Periodontitis). From the experiments, the following results were obtained. 1. When compared with normal, ${\gamma}-GTT$ of A. P. and R. P. P. were increased, and only the change of ${\gamma}-GTT$ of R. P. P. was statistically significant(P<0. 05). 2. The amounts of arachidonic acid metabolites were not different with statistical significance among the clinical groups. 3. ${\gamma}-GTT$ may by useful adjuncts as new cytoprotective indicator and periodontal disease activity indicator in accordance with positive corelation pocket depth, attachment level and ${\gamma}-GTT$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.437-440
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• 2004

The radiation-induced changes taking place in poly(vinylidene fluoride)(PVDF) exposed to $^{60}Co\;\gamma-ray$ irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by $^{60}Co\;\gamma-ray$ to doses in the range of 200 to 1000 kGy. Various properties of the irradiated PVDF were studied using nm, differential scanning calorimetry(DSC) and gel fraction. $^{60}Co\;\gamma-ray$ irradiation was found to induce changes in chemical, thermal, structural properties of PVDF and such changes vary depending on the radiation dose.

• BMB Reports
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• v.35 no.6
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• pp.590-594
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• 2002

To elucidate the effect of gamma-irradiation on the molecular properties of myoglobin, the secondary and tertiary structures, as well as the molecular weight size of the protein, were examined after irradiation at various irradiation doses. Gamma-irradiation of myoglobin solutions caused the disruption of the ordered structure of the protein molecules, as well as degradation, cross-linking, and aggregation of the polypeptide chains. A SDS-PAGE study indicated that irradiation caused initial fragmentation of the proteins and subsequent aggregation, due to cross-linking of the protein molecules. The effect of irradiation on the protein was more significant at lower protein concentrations. Ascorbic acid protected against the degradation and aggregation of proteins by scavenging oxygen radicals that are produced by irradiation. A circular dichroism study showed that an increase of the irradiation decreased the a-helical content of myoglobin with a concurrent increase of the aperiodic structure content. Fluorescence spectroscopy indicated that irradiation increased the emission intensity that was excited at 280 nm.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.954-958
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• 2014

Succinic semialdehyde dehydrogenase (SSADH) catalyzes the oxidation of succinic semialdehyde (SSA) into succinic acid in the final step of ${\gamma}$-aminobutyric acid degradation. Here, we characterized Bacillus subtilis SSADH (BsSSADH) regarding its cofactor discrimination and substrate inhibition. BsSSADH showed similar values of the catalytic efficiency ($k_{ca}t/K_m$) in both $NAD^+$ and $NADP^+$ as cofactors, and exhibited complete uncompetitive substrate inhibition at higher SSA concentrations. Further analyses of the sequence alignment and homology modeling indicated that the residues of catalytic and cofactor-binding sites in other SSADHs were highly conserved in BsSSADH.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.2
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• pp.1-6
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• 2009

The experimental results of exposing IGBT (Insulated Gate Bipolar Transistor) samples to gamma radiation source show shifting of threshold voltages in the MOSFET and degradation of carrier mobility and current gains. At low total dose rate, the shift of threshold voltage is the major contribution of current increases, but for more than some total dose, the current is increased because of the current gain degradation occurred in the vertical PNP at the output of the IGBTs. In the paper, the collector current characteristics as a function of gate emitter voltage (VGE) curves are tested and analyzed with the model considering the radiation damage on the devices for gate bias and different dose. In addition, the model parameters between simulations and experiments are found and studied.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1623-1634
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• 2022

A new irradiation loop design has been developed, which provides the ability to carry out radiolytic resistance studies of extraction systems simulating process relevant conditions in an easy and simple way. The step-by-step loop configuration permits an easy modification of settings and has a relative low volume requirement. This irradiation loop has been initially set up to test the main EURO-GANEX process steps: the lanthanide (Ln) and actinide (An) co-extraction followed by the transuranic (TRU) stripping. The performance and changes in the composition have been analyzed during the irradiation experiment by different techniques: gamma spectroscopy and ICP-MS for the extraction and corrosion behavior of the full system, and HPLC-MS and Raman spectroscopy to determine the degradation of the organic and aqueous solvents, respectively. The Ln and An co-extraction step and the corrosion that occurred during the first irradiation step revealed the favorable expected results according to literature. The effects of acidity changes occurred during the irradiation process, the presence of stainless corrosion products in solution as well as the new possible degradation compounds have been explored in the An stripping step. The results obtained demonstrate the importance of developing realistic irradiation experiments where different factors affecting the performance can be easily studied and isolated.

• Environmental Engineering Research
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• v.25 no.4
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• pp.614-621
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• 2020

Antibiotic pollution is one of the factors contributing to the spread of antibiotic-resistant bacteria in the environment. Advanced oxidation and irradiation processes have been introduced to eliminate antibiotics from water and wastewater. However, few studies have reported the toxic effects of residual antibiotics and their byproducts induced by a treatment system. In this study, we compared the efficacies of chemical (high-performance liquid chromatography (HPLC)) and biological (antimicrobial susceptibility test) assays for measuring the concentrations of residual antibiotics after gamma irradiation for degrading amoxicillin, cephradine, lincomycin, and tetracycline. The concentrations of residual antibiotics estimated using the two assay methods were almost identical, except cephradine. In the case of cephradine, inhibited bacterial growth was observed that was equivalent to twice the concentration measured by HPLC in the samples subjected to gamma irradiation. The observed inhibition of bacterial growth suggested the generation of potentially toxic intermediates following antibiotic degradation. These results indicate that biological and chemical assays should be used in concert for monitoring antibiotic contamination and the toxic derivatives of antibiotic degradation. The results demonstrate that these four antibiotics can be decomposed by 2.0 kGy gamma-irradiation without toxic effects of their byproducts.

• Korean Journal of Head & Neck Oncology
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• v.18 no.2
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• pp.142-149
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• 2002

Objectve : Okadaic acid is a specific inhibitor of serine/threonine protein phosphatase 1 and 2A. In order to know the mechanism of apoptosis induced by okadaic acid, we treated FRTL-5 thyroid cells with okadaic acid and measured the changes of important proteins that are involved in apoptosis. Materials and Methods: We measured caspase 3 activity, $PLC-{\gamma}1$ degradation, the expression of XIAP, cIAP1, cIAP2, and cytochrome c release in okadaic acid-treated FRTL-5 thyroid cells. Results: Okadaic acid-induced caspase 3 activation and $PLC-{\gamma}1$ degradation and apoptosis were dose-dependent with a maximal effect at a concentration of 80 nmol and time-dependent with a maximal effect at 24 hours after treatment. The elevated caspase 3 activity in okadaic acid treated FRTL-5 thyroid cells are correlated with down-regulation of XIAP and cIAP1, but not cIAP2. General and potent inhibitor of caspases, z-VAD-fmk. abolished okadaic acid-induced caspase 3 activity and $PLC-{\gamma}1$ degradation. The release of cytochrome c in okadaic acid-induced FRTL-5 thyroid cells was dose-dependent with a maximal effect at a concentration of 80 nmol. Conclusions: These findings suggest that mechanism of okadaic acid-induced apoptosis is associated with cytochrome c release and increase of caspase 3 activation in FRTL-5 thyroid cells.

• Journal of Radiation Industry
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• v.4 no.1
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• pp.39-45
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• 2010

The pollution of antibiotics is a major cause of spreading antibiotics resistant bacteria in the environment. Applications of ozonation, UV, and ${\gamma}-ray$ irradiations have been introduced to remove antibiotics in the effluents from wastewater treatment system. In this study, we compared the chemical (HPLC) and biological (antimicrobial susceptibility test, AMS) assays in measuring of the concentrations of residual antibiotics after ${\gamma}-ray$ and UV irradiation. Most samples were degraded by ${\gamma}-ray$ irradiation (1~2 kGy). However, lincomycin and tetracycline were not degraded by UV irradiation. The concentration of residual antibiotics, that was treated with ${\gamma}-ray$ and UV irradiation, measuring by bioassay was similar to HPLC. The concentrations of ${\gamma}-ray$ irradiated cephradine measured by AMS test were 2 times higher than that of HPLC assay, indicating AMS test is more sensitive than HPLC assay. These results indicate that ${\gamma}-ray$ irradiation technique is more useful than UV irradiation, and biological assay is more useful to detect the antibiotics and toxic intermediates in antibiotics degradation.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.4
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• pp.239-246
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• 2003

The expression of cyclooxygenase-2 (COX-2) is a characteristic response to inflammation and can be inhibited with sodium salicylate. $TNF-{\alpha}$ plus $IFN-{\gamma}$ can induce extracellular signal-regulated kinase (ERK), IKK, $I{\kappa}B$ degradation and NF-${\kappa}B$ activation. The inhibition of the ERK pathway with selective inhibitor, PD098059, blocked cytokine-induced COX-2 expression and $PGE_2$ release. Salicylate treatment inhibited COX-2 expression induced by $TNF-{\alpha}$/$IFN-{\gamma}$ and regulated the activation of ERK, IKK and $I{\kappa}B$ degradation and subsequent NF-${\kappa}B$ activation in MC3T3E1 osteoblasts. Furthermore, antioxidants such as catalase, N-acetyl-cysteine or reduced glutathione attenuated COX-2 expression in combined cytokines-treated cells, and also inhibited the activation of ERK, IKK and NF-${\kappa}B$ in MC3T3E1 osteoblasts. In addition, $TNF-{\alpha}$/$IFN-{\gamma}$ stimulated ROS release in the osteoblasts. However, salicylate had no obvious effect on ROS release in DCFDA assay. The results showed that salicylate inhibited the activation of ERK and IKK, $I{\kappa}B$ degradation and NF-${\kappa}B$ activation independent of ROS release and suggested that salicylate exerts its anti-inflammatory action in part through inhibition of ERK, IKK, $I{\kappa}B$, $NF-{\kappa}B$ and resultant COX-2 expression pathway.