• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1071-1075
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• 2003

In this paper, we present a DNA manipulation device in the reaction chamber, which consists of a center electrode and circular outer electrodes of a reaction unit. The charged bio-molecules, DNA, are manipulated by the charge of the electrode in reaction unit. Controlling the induced dynamic electric field between the center electrode and the outer electrodes, concentration / repulsion / manipulation of bio-molecules are enabled at a periphery of electrode. Concentration of the fluorescent DNA at the center electrode is observed by applying ＋2V. Subsequently, applying －2V, the concentrated DNA is repelled rapidly from the center electrode, which makes dispersion completely in 0.5second. Furthermore, repeated applying ＋1V/－1V every 5 seconds at each outer electrode, we can circulate the DNA. We also investigate a micro-heater and sensor for DNA manipulation and reaction temperature. The coefficient of heat-resistance and heater temperature characteristic is 0.0043 and 100$^{\circ}C$/sec, respectively.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.44-48
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• 2004

The two-component type enzyme amplified amperometric DNA assay is described to use an ambient $O_2$ of the substrate of the DNA labeling enzyme. Although the assay detects DNA only at > 0.5M concentration, a concentration $\~10^6$ fold higher than the sandwich-type enzyme amplified amperometric DNA assay, it can be run with an always available substrate. The assay utilizes screen-printed carbon electrodes (SPEs) which were pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a 37-base long single-stranded DNA sequence. The DNA in the electron conducting film hybridizes and captures, when present, the 37-base long detection-DNA, which is labeled with bilirubin oxidase (BOD), an enzyme catalyzing the four-electron reduction of $O_2$ to water. Because the redox hydrogel electrically connects the BOD reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electrocatalytic for the reduction of $O_2$ to water when the electrode is poised at 200 mV vs. Ag/hgCl. The advantage or the assay over the earlier reported sandwich type enzyme amplified amperometric DNA assay, in which the amplifying enzyme was horseradish peroxidase, is that it utilizes ambient $O_2$ instead of the less stable and naturally unavailable $H_2O_2$.

• Archives of Pharmacal Research
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• v.26 no.6
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• pp.493-498
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• 2003

In this study we have investigated the pharmacokinetics and tissue distribution of GX-12, a multiple plasmid DNA vaccine for the treatment of HIV-1 infection. Plasmid DNA was rapidly degraded in blood with a half-life of 1.34 min and was no longer detectable at 90 min after intravenous injection in mice. After intramuscular injection, plasmid DNA concentration in the injection site rapidly declined to less than 1 ％ of the initial concentration by 90 min post-injection. However, sub-picogram levels (per mg tissue) were occasionally detected for several days after injection. The relative proportions of the individual plasm ids of GX-12 remained relatively constant at the injection site until 90 min post-injection. The concentration of plasmid DNA in tissues other than the injection site peaked at 90 min post-injection and decreased to undetectable levels at 8 h post-injection. The rapid in vivo degradation of GX-12 and absence of persistence in non-target tissues suggest that the risk of potential gene-related toxicities by GX-12 administration, such as expression in non-target tissues, insertional mutagenesis and germline transmission, is minimal.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.86-90
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• 2011

The effects of cations are very important in field-effect transistors (FETs) type DNA sensors detecting the intrinsic negative charge between single-stranded DNA and double-stranded DNA without labeling, because the intrinsic negative charge of DNA is neutralized by cations in electrolyte solution. We consider the Debye length, which depends on the concentration of cations in solution, to detect DNA hybridization based on the intrinsic negative charge of DNA. The Debye length is longer in buffer solution with a lower concentration of NaCl and the intrinsic negative charge of DNA is more effective on the channel surface in longer Debye length solution. The shifts in the gate voltage by DNA hybridization with complementary target DNA are 21 mV in 1 mM NaCl buffer solution, 7.2 mV in 10 mM NaCl buffer solution, and 5.1 mV in 100 mM NaCl buffer solution. The sensitivity of FETs to detect DNA hybridization based on charge detection without labeling depends on the Debye length.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.554-560
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• 2023

To prevent illegal timber distribution, DNA markers have been used to identify the species and origin. However, extracting high-quality DNA from timber is difficult because of its physical and chemical properties. In this study, we investigated whether the age of timber tissue influences the yield of DNA extraction and the success rate of polymerase chain reaction (PCR) to understand the relationship between the establishment time of the wood annual ring and the extracted DNA concentration (ng/μl), purity (A260/A280), and PCR success rate (%) from pinewood, a major Korean domestic species. According to the results, it was observed that as the distance from the cambium increased, indicating that the tissue was older, the concentration and purity of the extracted DNA decreased significantly. For the trnM-trnV (285 bp) and rpoC1 (298 bp) regions, the PCR success rate was 100%. However, for the rbcL (1.3 kb) region, the PCR success rate was 66.67%. Moreover, PCR amplification of the rbcL region failed at all points older than 30 years. Thus, it is deduced that as time passes, along with the decay of timber cells, DNA is degraded, leading to a decrease in DNA concentration, purity, and PCR success rate. The results of this study are expected to be beneficial for future applications, such as the species identification of timber, providing valuable insights and potential utilization in this field.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.435-441
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• 2010

We report the preparation and characterization of a new and water soluble complex of palladium(II) with 1,10- phenanthroline and butyldithiocarbamate ligands. This compound has been studied through spectroscopic techniques, $^1H$ NMR, IR, electronic spectra and elemental analysis and conductivity measurements. The complex shows 50% cytotoxic concentration ($Ic_{50}$) value against chronic myelogenous leukemia cell line, K562, much lower than that of cisplatin. Thus the mode of binding of this complex to calf thymus DNA have been extensively investigated by isothermal titration UV-visible spectrophotometry, fluorescence, gel filteration and other methods. UV-visible studies show that the complex exhibits cooperative binding with DNA and remarkably denatures the DNA at extremely low concentration ($~13\;{\mu}M$). Fluorescence studies indicate that the complex intercalate into DNA. Gel filtration studies suggest that the binding of Pd(II) complex with DNA is strong enough that it does not readily break. In these interaction studies, several thermodynamic and binding parameters are also determined which may reflect the mechanism of action of this type of compound with DNA.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.520-526
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• 2017

Carnosine was recently reported to protect against the DNA damage induced by oxidative stress. In this study, we investigated the protective effect of eel Anguilla japonica carnosine extracts prepared using different methods (heat treatment extracts, HTEs; ion exchange chromatography, IEC; ultrafiltration permeation, UFP) on leukocyte DNA damage using the comet assay. Human leukocytes were incubated with extracts of eel carnosine at concentrations (of 10, 50, $100{\mu}g/mL$), and then subjected to an oxidative stimulus [$200{\mu}M$ hydrogen peroxide ($H_2O_2$)]. Pretreatment of the cells for 30 min with carnosine significantly reduced the genotoxicity of $H_2O_2$ measured as DNA strand breaks. The protective effects of the three types of extract (HTE, IEC, and UFP) increased with concentration. At the highest concentration (100 g/mL). there were no statistical differences in oxidative damage between each extract treatment and PBS-treated negative controls. When leukocytes were incubated with carnosine for 30 min after exposure to $H_2O_2$. the protective ability of each extract changed. Therefore, eel carnosine inhibits the $H_2O_2$ induced damage to cellular DNA in human leukocytes, supporting the protective effect of this compound against oxidative damage.

• Journal of Aquaculture
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• v.16 no.3
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• pp.196-201
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• 2003

Sessile organisms such as the oyster Crassostrea gigas have been given much attention as a potential biomonitoring indicator to assess the impact of toxicants on aquatic organism. In this study, we exposed cells isolated from gill of oyster (Crassostrea gigas) to hydrogen peroxide in vitro. In addition oysters were in vivo exposed to pyrene and benzo(a)pyrene at various concentrations for 2 weeks. Comet assay was used to detect DNA single strand breaks and to investigate the application of this technique as a tool for aquatic biomonitoring. Hydrogen peroxide increased DNA single strand break with increasing concentration after 30 minutes exposure in vitro. Pyrene and benzo(a)pyrene caused DNA damage only at very high concentration (100 $\mu\textrm{g}$/L or 1000 $\mu\textrm{g}$/L) at two week exposure in vivo. DNA damage was relatively higher at hemocyte than at gill. It suggested that metabolized PAHs are transferred to hemolymph from digestive gland which have a relatively high enzyme activity, and attacked the DNA of hemocyte, while gill accumulated PAHs without degrading them to their metabolites due to low enzyme activity at gill. Both in vitro and in vivo exposure experiments showed that the comet assay is an effective tool on screening whether the organism are exposed to genotoxic contaminants.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.943-947
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• 2003

We have studied the migration behavior of single-stranded DNA using capillary gel electrophoresis under various conditions. It was found that optimum electric fields should be less than 150 V/cm for the good tradeoff between the separation time and the resolution. It seems that the gel matrix with the combination of different polymer average molecular weights is important to extend the maximum readable DNA bases. The total gel concentration less than 3.1% in the mixed gel system showed good separation efficiency up to 600 bases. The best result was obtained with the poy(ethylene)oxide (PEO) gel concentration of 1.2% of Mr 8,000,000 and 1.8% of Mr 600,000. We observed that the capillary length between 50 cm to 100 cm (effective length) should be employed for the optimization between the total DNA migration time and the maximum readable length. A trizma base-boric acid-ethlyenediaminetetraacetic acid (EDTA) (TBE) buffer was commonly used for DNA sequencing, but we found that 3-[tris(hydroxymethyl)methyl amino]-1-propane sulfonic acid (TAPS) buffer worked as well for the single-stranded DNA separation. Especially, TAPS buffer showed a good resolution for very short DNA bases (1 to 30 bases).

• Korean Journal of Veterinary Research
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• v.24 no.1
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• pp.40-49
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• 1984

To investigate the factors influencing the artifical transformation in Escherichia coli, E. coli C600 was transformed by pBR322 DNA with tetracycline and ampicillin resistant gene purified by CsCl-Etbr equilibrium density gradient centrifugation from E.coli HB 101. The influencing factors in the transformation such as concentration of calcium chloride, time of ice incubation, temperature and time of heat shock, time of gene expression, effects of plasmid DNA concentration and adding time were examined in these experiments. The results obtained were as follows; 1. The highest transformation frequency was observed in the treatments of 100 mM $CaCl_2$ before heat shock and the treatment of $CaCl_2$ was essential step in the process of E. coli transformation. 2. The highest transformation frequency was observed in the treatment of heat shock at $42^{\circ}C$ for 4 min. or $37^{\circ}C$ for 6 min., but the prolonged heat shock resulted a decreased transformation frequency. 3. Treatments of ice incubation at $0^{\circ}C$ for 45 min. before heat stocks or at $0^{\circ}C$ for 30min. after heat shock resulted an increased transformation frequency. 4. There was a linear relationship between DNA concentration and transformation frequency at the concentration of $8{\times}10^3$ recipient cells. The highest transformation frequency reached in carte of 7 mcg of donor DNA, but above 1 mcg of DNA concentration, transformation frequency was not remarkably increased. Addition of donor DNA just after the treatment of $CaCl_2$ was the best. 5. The best condition of gene expression at $37^{\circ}C$ were 40min. for TC-resistant gene and 100min. for AP-resistant gene. TC-resistant gene was higher in the transformation frequency and faster in the gene expression time than AP-resistant gene. In these results, the best conditions for the transformation of E. coli C 600 with pBR322 DNA were: treatment with 100mM $CaCl_2$, ice incubation at $0^{\circ}C$ for 45 min, heat shock at $42^{\circ}C$ for 4 min., 30 min. of ice incubation and incubation at $37^{\circ}C$ for 100min. for gene expression in that order.