• Journal of the korean academy of Pediatric Dentistry
• /
• v.30 no.4
• /
• pp.626-636
• /
• 2003

Pediococcus pentosaceus K1270 was isolated from naturally fermented kimchi and identified based on the 16S rDNA sequence as well as cultural and biochemical characteristics. This strain strongly inhibited the formation of biofilm by Streptococcus mutans Ingbritt. K1270 also showed antibacterial activity against S. mutans Ingbritt. It was observed that K1270 strain produced hydrogen peroxide on MRS agar supplemented with 3, 3, 5, 5-tetramethylbenzidine (TMB) and peroxidase and the inhibitory effect of K1270 strain on the biofilm formation was reversed by the addition of catalase in part. Culture supernatant of K1270 inhibited the biofilm formation and the multiplication of S. mutans Ingbritt. This inhibitory effect of culture supernatant was decreased slightly by the addition of catalase and abolished by heat or trypsin treatment. Thus, this study suggests that P. pentosaceus K1270 inhibit the biofilm formation through the inhibition of the replication of S. mutans Ingbritt by producing hydrogen peroxide and bacteriocin.

• Korean Journal of Food Science and Technology
• /
• v.37 no.5
• /
• pp.717-722
• /
• 2005

Formation mechanisms of light-induced volatile compounds were studied using riboflavin-photosensitized oleic acid model systems. Volatile compounds in model systems with 4000 ppm riboflavin at $35^{\circ}C$ under light or in the dark for 39 hr were isolated and identified by a combination of solid phase microextraction (SPME), gas chromatography (GC), and mass spectrometry (MS). Total volatiles in oleic acid with riboflavin under light for 13, 26, and 39 hr increased by 90, 190, and 270%, respectively, compared to those in oleic acid without riboflavin under light. Total volatiles in samples without riboflavin under light or samples with riboflavin in the dark were not significant in tested conditions (p>10.05). Riboflavin did not act as a photosensitizer when it was dispersed in oleic acid. Heptane, octane, heptanal, octanal, nonanal, and 2-nonenal were significantly increased in riboflavin-photosensitized samples compared to those in samples without riboflavin (p<0,05). Light-induced volatile compounds including heptanal and 2-nonenal from oleic acid could be explained using singlet oxygen oxidation, the formation mechanism of which were not understood using triplet oxygen oxidation. These results will help to understand volatile formation in oleic acid containing foods stored under light.

• The Korean Journal of Pharmacology
• /
• v.30 no.3
• /
• pp.273-289
• /
• 1994

Reversible brain ischemia was produced by occluding both common carotid arteries for 5 min, and the effects of aminoguanidine (AG), $DL-{\alpha}-difluoromethylornithine$ (DFMO), MK-801, and nimodipine (NM) on the ischemia induced changes of the polyamine, glutamate and acetylcholine levels in the hippocampus CA1 subfield and the specific $[^3H]\;MK-801$ binding to the hippocampus synaptosomal membranes were studied with a histological reference of the cresyl violet stained hippocampus. The basal putrescine level $(PT:\;74.4{\pm}8.8\;nM)$ showed a rapid increase (up to 1.7 fold) for 5 min of ischemia, remained significantly increased for 6 h, and then resumed the further increase to amount gradually up to about 3 fold 96 h after recirculation. However, the level of spermidine was little changed, and the spermine level showed a transient increase during ischemia followed by a sustained decrease to about 40% of the preischemic level after recirculation. The increase of PT level induced by brain ischemia was enhanced with AG or MK-801, but it was reduced by DFMO or NM. The basal glutamate level $(GT:\;0.90{\pm}0.l4\;{\mu}M)$ rapidly increased to a peak level of $8.19{\pm}1.14\;{\mu}M$ within 5 min after onset of the ischemia and then decreased to the preischemic level in about 25 min after recirculation. And NM reduced the ischemia induced increase of GT level by about 25%, but AG, DFMO and MK-801 did not affect the GT increase. The basal acetylcholine level $(ACh:\;118.0{\pm}10.5\;{\mu}M)$ did little change during/after brain ischemia and was little affected by AG or NM. But DFMO and MK-801, respectively, produced the moderate decrease of ACh level. The specific $[^3H]\;MK-801$ binding to the hippocampus synaptosomal membrane was little affected by brain ischemia for 5 min. The control value (78.9 fmole/mg protein) was moderately decreased by AG and MK-801, respectively but was little changed by DFMO or NM. The microscopic findings of the brains extirpated on day 7 after ischemia showed severe neuronal damage of the hippocampus, particularly CA1 subfield. NM and AG moderately attenuated the delayed neuronal damage, and DFMO, on the contrary, aggravated the ischemia induced damage. However, MK-801 did not protect the hippocampus from ischemic damage. These results suggest that unlike to the mode of anti-ischemic action of NM, AG might protect the hippocampus from ischemic injury as being negatively regulatory on the N-methyl-D-aspartate (NMDA) receptor function in the hippocampus.

• The Korean Journal of Nuclear Medicine
• /
• v.36 no.4
• /
• pp.261-270
• /
• 2002

Purpose: Nicotinic acetylcholine receptors (nAChRs), which mediate excitatory neurotransmission, are known to participate in various neurophysiological functions. Severe losses of nAChRs have been noted in Alzheimer's and Parkinson's diseases. Therefore, noninvasive and quantitative imaging of nAChRs would offer a better understanding on the function of these receptors. In this study, $2-[^{18}F]fluoro-A85380\;([^{18}F]1)$, an ${\alpha}_4{\beta}_2$ nAChRs radioligand, was prepared using one HPLC purification and evaluated in mouse brain, and the results were compared with those in the literature. Materials and Methods: $[^{18}F]1$ was prepared by $[^{18}F]$fluorination of the iodo precursor followed by acidic deprotection and then purified by HPLC. Tissue distribution studies were performed in mouse brain at the indicated time points and the result was expressed as %ID/g. Inhibition studies were also carried out with pretreatment of various ligands. Results: One HPLC purification method gave the desired product in 15-20% radiochemical yield and with high specific activity ($38-55GBq/{\mu}mol$). Tissue distribution studies showed that $[^{18}F]1$ specifically labeled nAChRs in mouse brain with a high thalamus to cerebellum uptake ratio (13.8 at 90 min). Inhibition studios demonstrated selective binding of $[^{18}F]1$ to nAChRs, blocking the uptake of the $[^{18}F]1$ in nAChR-rich legions by selective ligands such as cytisine and nicotine which are well-known nAChRs agonists. Conclusion: This study demonstrated that the $[^{18}F]1$ produced by the method using one HPLC purification gave the results similar to those reported in the literature. Therefore, this synthetic method can be readily applied to the routine preparation of $[^{18}F]1$, a PET radioligand for ${\alpha}_4{\beta}_2$ nAChRs imaging.

• Nuclear Medicine and Molecular Imaging
• /
• v.43 no.4
• /
• pp.337-343
• /
• 2009

Purpose: ((R)-1-(2-chlorophenyl)-N-1-[$^{11}$C]methyl-N(1-propyl)-3-isoquinoline carboxamide ((R)-PK11195) is a specific ligand for the peripheral type benzodiazepine receptor and a marker of activated microglia, used to measure inflammation in neurologic disorders. We report here that a direct and simple radiosynthesis of [$^{11}$C](R)-PK11195 in mild condition using NaH suspension in DMF and one-step loop method. Materials and Methods: (R)-N-Desmethyl-PK11195 (1 mg) in DMSO (0.1 mL) and NaH suspension in DMF (0.1 mL) were injected into a semi-prep HPLC loop. [$^{11}$C]methyl iodide was passed through HPLC loop at room temperature. Purification was performed using semi-preparative HPLC. Aliquots eluted at 11.3 min were collected and analyzed by analytical HPLC and mass spectrometer. Results: The labeling efficiency of [$^{11}$C](R)-PK11195 was 71.8$\pm$8.5%. The specific activity was 11.8:$\pm$6.4 GBq/$\mu$mol and radiochemical purity was higher than 99.2%. The mass spectrum of the product eluted at 11.3 min showed m/z peaks at 353.1 (M+1), indicating the mass and structure of (R)-PK11195. Conclusion: By the one-step loop method with the [$^{11}$C]CH3l automated synthesis module, [$^{11}C$](R)-PK11195 could be easily prepared in high radiochemical yield using NaH suspension in DMF.

• Korean Journal of Food Science and Technology
• /
• v.31 no.1
• /
• pp.91-98
• /
• 1999

Plums (Prunus salicina L.) were coated with calcium-treated methylcellulose (CaMC) and hydroxypropylmethylcellulose-15 (CaHPMC-15). Respiration rate, weight loss, pH and titratable acidity, texture, and sensory characteristics were compared during 8-day storage period at $30^{\circ}C$. Weight loss and respiration rate of plums coated with CaMC and CaHPMC-15 were lower than those of control plums during storage while pH increased and titratable acidity slowly deceased during storage. Mechanical firmness was significantly deceased during storage, in which CaMC and CaHPMC-15-coated plums were harder than the control. Amount of soluble pectin, and pectin esterase and polygalacturonase activities as the markers of softening commonly increased with storage, but both CaMC and CaHPMC-15-coated plums were not found those increases. Sensory evaluation showed that the flesh softening of plums decreased during storage, and that in the coated plums exhibited the harder flesh. In conclusion, introduction of CaMC and CaHPMC-15 coatings on plums decreased respiration rate and contributed to delay of flesh softening, and the significant difference in postharvest storage quality of the both plums were not found between CaMC and CaHPMC-15 coatings.

• Informatization Policy
• /
• v.22 no.4
• /
• pp.22-44
• /
• 2015

With the growing interest being reflected in the FinTech industry, much attention has been paid to mobile easy payment services as well. In the era of mobile commerce, the core advantage of using mobile easy payment services(simplifying complex payment procedures and thus facilitating user convenience and reducing the chance of giving up payment) are being more emphasized. Mobile easy payment service market not only includes mobile easy payment service providers but also users, non-users, affiliates, banks, and credit card companies as main stakeholders. Exploring those stakeholders is thus important to thoroughly understand such market. However, extant literature on mobile easy payment services mostly focuses on examining adoption intention of users or non-users. This study, an exploratory research based on interviews, thus aims to extract driving as well as inhibiting factors of mobile easy payment service use from six different perspectives (i.e., social platform, bank, credit card company, affiliate, user, and non-user) and analyze a sequence of cause and effect for each factor. For this, the causal loop diagram was developed to deduce key issues and propose an alternative. Theoretical and practical implications of this study will also be discussed.

• Korean Journal of Food Science and Technology
• /
• v.33 no.3
• /
• pp.378-383
• /
• 2001

Formation of superoxide anion $O_2\bar{{\bullet}}$ in the autoxidation of L-ascorbic acid (AsA) in the presence of heavy metal ions were determined. The generation of $O_2\bar{{\bullet}}$ was studied by using superoxide dismutase (SOD) in aqueous and buffer solution, and using nitro bule tetrazolium (NBT) in methanol solution. The remaining amount of AsA was significantly higher in the presence of SOD than in its absence. It suggested that SOD stabilizes AsA in aqueous and buffer solution because of scavenging $O_2\bar{{\bullet}}$ formed during the autoxidation reaction of AsA in the presence of heavy metal ions. NBT has an absorption maximum at about 560 nm in methanol solution. The absorbance at 560 nm increased during the oxidation of AsA, suggested the formation of $O_2\bar{{\bullet}}$in methanol solution. Thus, the formation of $O_2\bar{{\bullet}}$ was confirmed during the autoxidation of AsA not only in aqueous solution but also in methanol solution in the presence heavy metal ions.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.6
• /
• pp.454-459
• /
• 2009

In order to identify the effect of soil salinity on saturated hydraulic conductivity in reclaimed paddy soils, we established the soil columns uniformly packed with soils collected at every 20 cm up to 60 cm from the reclaimed paddy area with high and low salinity which has been cultivated rice plants for the last 30 years. The soil textures were sandy loam and loamy sand for high-salinity and low-salinity topsoils, respectively. For high-salinity and low-salinity soils the ECes were ranged from 25.2 to $37.8dS\;m^{-1}$ and 3.0 to $3.4dS\;m^{-1}$ while the ESPs were ranged from 7.70 to 20.84 % and from 5.12 to 11.33 %, respectively. The bulk densities of the soil columns were adjusted to $1.15{\pm}0.03g\;cm^{-3}$. The results of the soil column experiments shows that the stabilized saturated hydraulic conductivity of low-salinity soil was $0.62cm\;hr^{-1}$ at the topsoil while there were little water flow at the bottom of the soil columns packed with high-salinity soils. After removal of $Na^+$ ions with $1N\;NH_4OAc$ from the high-salinity soil, Ksat of the saline soil was drastically increased to $0.23cm\;hr^{-1}$. Soil columns of high-salinity topsoil treated with four different concentration of NaCl influent after removal of soluble and exchangeable cations with $1N\;NH_4OAc$ show Ksat in the range of $0.1{\sim}0.15cm\;hr^{-1}$ and the Ksat slightly decreased as the concentration of NaCl influent was increasing. Conclusively, we could assume that $Na^+$ can be significantly contributed to the saturated hydraulic conductivity in newly reclaimed sandy soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.38 no.1
• /
• pp.15-24
• /
• 2005

Enterobacter intermedium oxidizes glucose to gluconic acid and sequentially converts gluconic acid to 2-ketogluconic acid (2-KGA) under aerobic condition. Shaking incubation of E. intermedium in a broth medium containing 22.5 g glucose, 8.2 g gluconic acid and 40 g rock phosphate per liter resulted in $1028mg\;L^{-1}$ soluble phosphate. The culture broth was used as phosphate bio-fertilizer (PBF) in this experiment. To evaluate PBF produced by E. intermedium on lettuce growth, five treatments (PBF1/3, PBF2/3, PBF3/3, BP, and MF) were used. In MF and BP treatments, $P_2O_5$ 5.9 kg of mineral fertilizer per 10a was added, while in PBF1/3, PBF2/3, and PBF3/3 treatments, culture broth containing one third, two third, and same amount of soluble $P_2O_5$ 5.9 kg per 10a was applied, respectively. At 20, 35, and 50 days after transplanting of lettuce, plant growth components, biomass, enzyme activities and soil chemical properties were analyzed. Dehydrogenase activity and available phosphate concentration of rhizosphere in phosphate bio fertilizer treatments (PBF1/3, PBF2/3, PBF3/3) were generally higher compared to MF and BP treatments. Soil biomass in PBF3/3 treatment was significantly higher than MF and BP treatments at early growth stage. However, there was no significant difference among all treatments with time. Plant fresh weights in PBF1/3, PBF2/3, and MF treatments were better than those in BP and PBF3/3 treatments. However, in PBF2/3 treatment the highest fresh weight was discovered where alkaline phosphatase activity was generally higher than other treatments at 35 and 50 days. Enhancement of lettuce growth at 35 and 50 days in PBF2/3 treatment was associated with greater phosphate uptake in lettuce tissue. As regarding all results, PBF showed better lettuce growth compared to mineral phosphate fertilizer where PBF2/3 treatment resulted in increase of lettuce fresh weight by 23% and phosphate uptake by 50%.