• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.285-294
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• 2010

The purpose of this study was to evaluate the viability of periodontal ligament cells of rat teeth after low-temperature preservation under high pressure by means of MTT assay, WST-1 assay. 12 teeth of Sprague-Dawley white female rats of 4 week-old were used for each group. Both side of the first and second maxillary molars were extracted as atraumatically as possible under tiletamine anesthesia. The experimental groups were group 1 (Immediate extraction), group 2 (Slow freezing under pressure of 3 MPa), group 3 (Slow freezing under pressure of 2 MPa), group 4 (Slow freezing under no additional pressure), group 5 (Rapid freezing in liquid nitrogen under pressure of 2 MPa), group 6 (Rapid freezing in liquid nitrogen under no additional pressure), group 7 (low-temperature preservation at $0^{\circ}C$ under pressure of 2 MPa), group 8 (low-temperature preservation at $0^{\circ}C$ under no additional pressure), group 9 (low-temperature preservation at $-5^{\circ}C$ under pressure of 90 MPa). F-medium and 10% DMSO were used as preservation medium and cryo-protectant. For cryo-preservation groups, thawing was performed in $37^{\circ}C$ water bath, then MTT assay, WST-1 assay were processed. One way ANOVA and Tukey HSD method were performed at the 95% level of confidence. The values of optical density obtained by MTT assay and WST-1 were divided by the values of eosin staining for tissue volume standardization. In both MTT and WST-1 assay, group 7 ($0^{\circ}C$/2 MPa) showed higher viability of periodontal ligament cells than other group (2-6, 8) and this was statistically significant (p < 0.05), but showed lower viability than group 1, immediate extraction group (no statistical significance). By the results of this study, low-temperature preservation at $0^{\circ}C$ under pressure of 2 MPa suggest the possibility for long term preservation of teeth.

• Journal of the Korean association of regional geographers
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• v.23 no.2
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• pp.403-419
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• 2017

This study analyzed the forces to drive the change of urban green spaces in Daegu from 1989 to 2009. First, the loss and fragmentation of green spaces in the past 20 years were spatially identified by performing the hot spots analysis for the cell-based spatial metrics quantifying the size and diversity of green spaces. Next, seven drivers such as slope, distance to roads, land price, population density, ratios of residential, commercial, and industrial areas were selected based on the previous studies and the direction of the association between the loss and fragmentation of green spaces and seven drivers was analyzed with the stepwise logistic regression. Finally, the relative importance of the seven drivers and their interactions in the past 20 years were analyzed with the geographical detector. The results show that the loss of green spaces was concentrated on a part of the Anshim housing development district from 1989 to 2009 and green spaces were highly fragmented around the housing development districts such as Seongseo, Anshim, Dalseong-gun and Chilgok. The forces to drive the loss and fragmentation of green spaces in these areas were different at the administrative levels, but the drivers such as slope and ratios of residential and industrial areas were commonly significant. These drivers were positively correlated with largest patch index(LPI) quantifying the loss of green spaces while they were negatively correlated with Shannon's diversity index(SHDI) measuring the fragmentation of green spaces. In other words, the loss and fragmentation of urban green spaces in Daegu appeared around such regions with lower slope and lower ratios of residential and industrial areas. The relative importance of drivers for LPI was listed as ratio of industrial area, land price, and ratio of commercial area in descending order whereas that of drivers for SHDI was listed as ratio of industrial area, land price, and distance to roads in descending order. Also, the interaction between slope and ratio of residential area had a great impact on LPI and SHDI. The ratio of industrial area was a single driver to most significantly explain the loss and fragmentation of urban green spaces in Daegu in the past 20 years. The interaction between slope and ratio of residential area was greater than the independent influence of a single driver. This study will provide the base data to build a sustainable urban green policy for the city of Daegu in the near future.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.198-203
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• 2007

DNA transfection is a powerful tool for studying gene functions. The $Ca^{2+}$-phosphate precipitation remains one of the most popular and cost-effective transfection techniques. Mature neurons are more resistant to transfection than young ones and most other cell types, and easy to die if microenvironment changes. Here, we report a transfection protocol for mature neurons. The critical modifications are inclusion of glial cells in culture and careful control of $Ca^{2+}$-phosphate precipitation under microscope. Cerebral glial cells were grown until ${\sim}70-80%$ confluence in DMEM/10% horse serum, which was thereafter replaced with serum-free Neurobasal/Ara-C, and 319 hippocampal neurons were plated onto the glial layer Formation of fine $DNA/Ca^{2+}$-phosphate precipitates was induced using Clontech $CalPhos^{TM}$ Mammalian Transfection Kit, and the size ($0.5-1\;{\mu}m$ in diameter) and density(about 10 particles/$100\;{\mu}m^2$) were carefully controlled by the time of incubation in the medium. This modified protocol can be reliably applied for transfection of mature neurons that are maintained longer than two weeks in vitro, resulting in 10-15 healthy transfected neurons per a well of 24-well plates. The efficacy of the protocol was verified by punctate expression of $pEGFP-CaMKII{\alpha}$, a synaptic protein, and diffuse expression of pDsRed2. Our protocol provides a reliable method for transfection of mature neurons in vitro.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.272-277
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• 1998

Filtering rates of two farming ascidians Styela clava and S. plicata, and of a farming mussel Mytilus edulis were experimentally investigated with reference to effects of water temperature and size. Absorptiometric determinations of filtering rates were carried out in a closed system with experimental animals being decreased indicate dyes neutral red. Optical density (OD) of 440 nm in path length 22 mm cell used as the indication of food particles absorption was appeared directly in proportion with the concentration of neutral red dyes. The filtering rate F is calculated by Kim's equation $F\;=\;V(1-e^{-z})$, where V is the water volume ($\ell$) in the experimental jar, and Z is the decreasing coefficient of OD as meaning of instantaneous removal speed as In $C_t\;=\;In\;C_{o}-Z{\cdot}t$, in this formula $C_t$ is OD at the time t. Filtering rate of S. clava increased as exponential function with increasing temperature while not over critical limit, and the critical temperature for filtering rate was assumed to be between $28^{\circ}C$ and $29^{\circ}C$. In case of S. plicata, the critical temperature was to be below $13^{\circ}C$, and through the temperature range $15\~25^{\circ}C$ appeared a little difference in level even though with significant. M. edulis was not appear any significant effects by water temperature less than $29^{\circ}C$. The model formula derived from the results is as below, where F is filtering rate (${\ell}/hr/animal$), T is water temperature ($^{\circ}C$), and DW is dry meat weight (g) of experimental animal. $$S.\;Clava;\;F\;=\;e xp\;(0.119\;T-4.540)\;(DW)^{0.6745},\;T<29^{\circ}C$$) $$S.\;plicata;\;F\;=\;e xp\;(A_t)\;(DW)^{0.5675},\;(13^{\circ}C $$[A_t =-8.56+0.6805\;T-0.0153\;T^2]$$ $$M.\;edulis;\;F\;=\;0.3844\;(DW)^{0.4952},\;<29^{\circ}C$$)

• Journal of Life Science
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• v.24 no.8
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• pp.820-826
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• 2014

The localization to specific subcellular sites and the regulation of cell surface receptors and channels are crucial for proper functioning. Postsynaptic density-95/Disks large/Zonula occludens-1 (PDZ)-domain is involved in recognition of and interaction between various proteins, by which the localization and the regulation are mediated. Multi-PDZ domain protein 1 (MUPP1) contains 13 PDZ domains. MUPP1 serves a scaffolding function for structure proteins and signaling proteins, but the mechanism how MUPP1 is stabilized and signalized has not yet been elucidated. We used the yeast two-hybrid system to identify proteins that interact with PDZ domains of MUPP1. We found an interaction between MUPP1 and Parkin. Parkin is an E3 ubiquitin ligase. Loss-of-function mutations of Parkin gene are known to cause an autosomal recessive juvenile parkinsonism. Parkin bound to the $12^{th}$ PDZ domain, but not to other PDZ domains of MUPP1. The C-terminal end of Parkin has a type II PDZ-association motif, which was essential for the interaction with MUPP1 in the yeast two-hybrid assay. When co-expressed in HEK-293T cells, Parkin co-localized with MUPP1. When co-expressed with ubiquitin in HEK-293T cells, MUPP1 has been strongly ubiquitinated by Parkin. These findings collectively suggest that MUPP1 is a novel substrate of Parkin and its function or stability could be modulated by Parkin-mediated ubiquitination.

• Applied Biological Chemistry
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• v.29 no.3
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• pp.288-293
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• 1986

The washed fresh ginsengs packed with air, vaccum and nitrogen gas were irradiated at the levels of 1,2 and 3kGy gamma radiation and then stored at $4{\sim}5^{\circ}C$ for 90days to investigate the effects of gamma radiation on microbial inactivation, eelworm disinfestation and physicochemical changes. After a 90 day storage, $2{\sim}3kGy$ irradiated groups showed 20% of weight loss and 10% of rot while non-irradiated group 100% and 20% or more, respectively. Also the irradiated groups showed somewhat lower values of specific gravity, color density and hardness immediately after irradiation, thereafter higher value of them with storage time than those of non-irradiated group. The irradiation increased the yields of ginseng extract and crude saponins but no effects on the proximate composition and TLC and HPLC patterns of saponin. The food-borne microorganisms decreased in viable cell counts by $2{\sim}3$ log cycles with $2{\sim}3kGy$ radiation and the eelworms were completely disinfested with 1 kGy radiation.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.851-870
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• 2000

The major goals of periodontal therapy is the functional regeneration of periodontal supporting structures already destructed by periodontal disease as well as the reduction of signs and symptoms of progressive periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. There have been increasing interest on the chitosan made by chitin. Chitin is second only to cellulose as the most abundant natural biopolymer. It is a structural component of the exoskeleton of invertebrates(e.g., shrimp, crabs, lobsters), of the cell wall of fungi, and of the cuticle of insects. Chitosan is a derivative of chitin made by deacetylation of side chains. Many experiments using chitosan in various animal models have proven its beneficial effects. The aim of this study is to evaluate the osteogenesis of chitosan on the calvarial critical size defect in Sprague Dawley rats. An 8 mm surgical defect was produced with a trephine bur in the area of the midsagittal suture. The rats were divided into two groups: Untreated control group versus experimental group with 50mg of soluble chitosan gel. The animals were sacrificed at 2, 4 and 8 weeks after surgical procedure. The specimens were examined by histologic, histomorphometric and radiodensitometric analyses. The results are as follows: 1. The length of newly formed bone in the defects was $102.91{\pm}25.46{\mu}m$, $219.46{\pm}97.81{\mu}m$ at the 2 weeks, $130.95{\pm}39.24{\mu}m$, $212.39{\pm}89.22{\mu}m$ at the 4 weeks, $181.53{\pm}76.35{\mu}m$ and $257.12{\pm}51.22{\mu}m$ at the 8 weeks in the control group and experimental group respectively. At all periods, the means of experimental group was greater than those of control group. But, there was no statistically significant difference between the two groups. 2. The area of newly formed bone in the defects was $2962.06{\pm}1284.48{\mu}m^2$, $5194.88{\pm}1247.88{\mu}m^2$ at the 2 weeks, $5103.25{\pm}1375.88{\mu}m^2$, $7751.43{\pm}2228.20{\mu}m^2$ at the 4 weeks and $8046.20{\pm}818.99{\mu}m^2$, $15578.57{\pm}5606.55{\mu}m^2$ at the 8 weeks in the control group and experimental group respectively. At all periods, the means of experimental group was greater than those of control group. The experimental group showed statistically significant difference to the control group at the 2 and 8 weeks. 3. The density of newly formed bone in the defects was $14.26{\pm}6.33%$, $27.91{\pm}6.65%$ at the 2 weeks, $20.06{\pm}9.07%$, $27.86{\pm}8.20%$ at the 4 weeks and $22.99{\pm}3.76%$, $32.17{\pm}6.38%$ at the 8 weeks in the control group and experimental group respectively. At all periods, the means of experimental group was greater than those of control group. The experimental group showed statistically significant difference to the control group at the 2 and 8 weeks. These results suggest that the use of chitosan on the calvarial defects in rats has significant effect on the regeneration of bone tissue in itself

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.6
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• pp.683-693
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• 2009

This study was designed to investigate the effect of dandelion juice supplementation on attenuation of oxidative stress and hangover after drinking alcohol in healthy college male students. This human trial was conducted by two phase cross over design with two weeks wash out period. The subjects (age $24{\sim}28$ years) were volunteers who had more than 72 g of ethanol drinking capacity. Dandelion group was given dandelion juice 220 mL daily for 7 days. Biochemical markers were determined in blood samples taken at 0 and 150 minutes after administration 72 g of alcohol. The levels of plasma glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactate dehydrogenase and bilirubin, the indicators of liver cell damage, were not significantly different between groups. No significant differences in lymphocyte DNA damage level between groups was observed. However, plasma acetaldehyde dehydrogenase (ALDH) and high density lipoprotein cholesterol levels were significantly (p<0.01) increased in dandelion supplemented group compared to that of control group. Furthermore, activities and protein expressions of glutathione-reductase and catalase of erythrocytes were significantly elevated in dandelion supplemented group compared to that of control group. From the above results, it is concluded that dandelion juice supplementation can reduce oxidative stress and hangover syndrome through the elevation of ALDH and antioxidative enzyme system in healthy male adults.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.328-336
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• 1997

The CdSe thin films were grown on the Si(100) wafers by a hot wall epitaxy method (HWE). The source and substrate temperature are $600^{\circ}C$ and $430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the temperature range 30K to 150K by impurity scattering and decreased in the temperature range 150k to 293k by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity(${\gamma}$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^{7}$, the MAPD of 335mW, and the rise and decay time of 10ms and 9.5ms, respectively.