• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.4
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• pp.389-396
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• 2024

Reactive oxygen species (ROS) generated by harmful algal blooms (HABs) exert detrimental effects on aquaculture systems. Fish gill cells deteriorate upon exposure to HABs, suggesting that internally generated ROS in HABs influences the external environment. Therefore, we investigated the internal and external changes in ROS concentrations during growth using fluorescence staining of four representative HABs: Alexandrium affine, Chattonella marina, Karenia mikimotoi, and Margalefidinium polykrikoides. The concentrations of H₂O₂ and O₂^- produced by A. affine were low; H₂O₂ from M. polykrikoides was primarily detected internally throughout the experiments, and O₂^- was not detected. High H₂O₂ and O₂^- concentrations were observed in K. mikimotoi during the death phase, with weak external O₂^- concentrations. Regarding C. marina, which produces large amounts of ROS, H₂O₂ was observed internally during the exponential phase, whereas weak O₂^- concentrations were measured externally in the stationary phases. Collectively, our results highlight that ROS concentrations and internal/external distributions are functions of HABs and growth stage. These differences indicate the potential allelopathic mechanisms of proliferating HABs and suggest a possible impact of ROS on aquaculture organisms.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2577-2582
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• 2013

A novel stick-shaped portable sensing device featuring a microhole array interface between the polyvinylchloride-2-nitrophenyloctylether (PVC-NPOE) gel and water phase was developed for in-situ sensing of perchlorate ions in real water samples. Perchlorate sensitive sensing responses were obtained based on measuring the current changes with respect to the assisted transfer reaction of perchlorate ions by a perchlorate selective ligand namely, bis(dibenzoylmethanato)Ni(II) (Ni(DBM)2) across the polarized microhole array interface. Cyclic voltammetry was used to characterize the assisted transfer reaction of perchlorate ions by the $Ni(DBM)_2$ ligand when using the portable sensing device. The current response for the transfer of perchlorate anions by $Ni(DBM)_2$ across the micro-water/gel interface linearly increased as a function of the perchlorate ion concentration. The technique of differential pulse stripping voltammetry was also utilized to improve the sensitivity of the perchlorate anion detection down to 10 ppb. This was acquired by preconcentrating perchlorate anions in the gel layer by means of holding the ion transfer potential at 0 mV (vs. Ag/AgCl) for 30 s followed by stripping the complexed perchlorate ion with the ligand. The effect of various potential interfering anions on the perchlorate sensor was also investigated and showed an excellent selectivity over $Br^-$, $NO_2{^-}$, $NO_3{^-}$, $CO{_3}^{2^-}$, $CH_3COO^-$ and $SO{_4}^{2^-}$ ions. As a final demonstration, some regional water samples from the Sincheon river in Daegu city were analyzed and the data was verified with that of ion chromatography (IC) analysis from one of the Korean-certified water quality evaluation centers.

• Archives of Plastic Surgery
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• v.35 no.3
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• pp.229-234
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• 2008

Purpose: There are some reports presenting that peripheral blood contain circulating hematopoietic cells as well as, in significantly smaller quantities, mesenchymal stem cells. The purposes of this study is to isolate and characterize circulating mesenchymal progenitor cells with osteogenic potential from human peripheral blood. Methods: Human buffycoat containing mononuclear cells was harvested from peripheral blood of normal persons and isolated using a density gradient centrifugation and serially subcultured in osteogenic media for 1-4 weeks. The proliferation capability, phase-contrast microscopy, transmission electron microscopy, immunophenotype FACS analysis, Alizarin red staining and RT-PCR assays for osteogenic differentiation potential were performed. Results: The phenotype of cultured cells changed from small round or cuboidal cells at passage 1 into large spindle-shaped fibroblastic morphology cells at passage 4. Surface marker expressed CD14, but did not express CD34, CD80, CD83. Strong positive staining was observed for Alizarin reds in osteogenic medium on day 14, Using RT-PCR, the mRNA levels of bone- specific genes, such as ALP, c-bfa-1 and osteocalcin were detected. Conclusion: A new subset of peripheral blood derived progenitor cells described here has the ability to proliferate and differentiate into osteogenic cell lineages in vitro, and to be candidate for regenerative therapy.

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.127-134
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• 2011

The purpose of this study was to purify antioxidant substances from steamed squid extract (SSE). The yield of SSE was 8% by dry weight. The approximate compositions of SSE proteins, lipids, moisture, carbohydrate and ash were 64.95%, 1.69%, 7.23%, 4.44% and 21.69%, respectively. The major amino acids in SSE were taurine (29.17%), glycine (20.33%), alanine (12.51%), and glutamic acid (9.83%). Antioxidant activities were evaluated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity, which was measured as 24.7% at 1.0 mg/mL. Four SSE fractions were isolated by Sephadex G-25 gel chromatography; the F2 fraction showed the highest DPPH radical scavenging activity. The F2 fraction was separated by reverse-phase high performance liquid chromatography (HPLC) using an octadecylsilane (ODS) column, yielding a purified antioxidant substance with a DPPH radical scavenging activity of 64.41% at 1.0 mg/mL, representing a 2.64-fold increase in the scavenging activity of SSE purified by the 3-step procedure. The amino acid compositions showed that purified SSE was rich in taurine, glycine, glutamic acid and alanine. The purified SSE significantly elevated 2',7'-dichlorodihydrofluororescein diacetate (DCFH-DA) fluorescence probe, which confirms its effective radical scavenging potential in cellular ROS. In addition, the SSE significantly inhibited oxidative damage of purified genomic DNA. These results suggest that a purified antioxidant substance from SSE can be used as a potential natural compound-based antioxidant in the functional food and pharmaceutical industries.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.2
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• pp.67-73
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• 2015

The microcystin is a cyclic heptapeptide from metabolites of cyanobacteria in the genera mycrocystis, anabaeba as a result of eutrophication. It has been known that microcystin-LR is a potent inhibitor of the catalytic subunits of protein phosphatase-1 (PP-1) as well as powerful tumor promoter. The active site of microcystin actually has two metal ions $Fe^{2+}/Zn^{2+}$ close to the nucleophilic portion of PP-1-microcystin complex. We report the isolation and purification of this microcystin-LR from cyanobacteria (blue-green algae) obtained from Daechung Dam in Chung-cheong Do, Korea. Microcystin-LR was extracted from solid-phase extraction (SPE) sample preparation using a CN cartridge. The cyanobacteria extract was purified to obtain microcystin-LR by HPLC method and identified by LC/MS. The detail structural studies that can elucidate the possible role of monovalent and divalent metal ions in PP-1-microcystin complexation were carried out by utilizing molecular dynamics. Conformational changes in metal binding for ligands were monitored by molecular dynamic computation and potential of mean force (PMF) using the method of the free energy perturbation. The microcystin-metal binding PMF simulation results exhibit that microcystin can have very stable binding free energy of -10.95 kcal/mol by adopting the $Mg^{2+}$ ion at broad geometrical distribution of $0.5{\sim}4.5{\AA}$, and show that the $K^+$ ion can form a stable metal complex rather than other monovalent alkali metal ions.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7421-7426
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• 2013

Background: Colorectal cancer is the fourth most common cancer worldwide and the second leading cause of cancer-related death. FOLFOX is the most common regimen used in the first-line chemotherapy in advanced colorectal cancer, but only half of the patients respond to this regimen and we have almost no clue in predicting resistance in such first-line application. Methods: To explore the potential molecular biomarkers predicting the resistance of FOLFOX regimen as the first-line treatment in advanced colorectal cancer, we screened microRNAs in serum samples from drug-responsive and drug-resistant patients by microarrays. Then differential microRNA expression was further validated in an independent population by reverse transcription and quantitative real-time PCR. Results: 62 microRNAs expressing differentially with fold-change >2 were screened out by microarray analysis. Among them, 5 (miR-221, miR-222, miR-122, miR-19a, miR-144) were chosen for further validation in an independent population (N=72). Our results indicated serum miR-19a to be significantly up-regulated in resistance-phase serum (p=0.009). The ROC curve analysis showed that the sensitivity of serum miR-19a to discriminate the resistant patients from the response ones was 66.7%, and the specificity was 63.9% when the AUC was 0.679. We additionally observed serum miR-19a had a complementary value for cancer embryonic antigen (CEA). Stratified analysis further revealed that serum miR-19a predicted both intrinsic and acquired drug resistance. Conclusions: Our findings confirmed aberrant expression of serum miR-19a in FOLFOX chemotherapy resistance patients, suggesting serum miR-19a could be a potential molecular biomarker for predicting and monitoring resistance to first-line FOLFOX chemotherapy regimens in advanced colorectal cancer patients.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.2
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• pp.100-106
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• 2018

Recently, the development of a heat pump technology to recover process waste heat and to generate steam of $120^{\circ}C$ or higher required for industrial processes, has attracted attention. The research of conventional heat pump utilizing the available energy is used primarily for air conditioning, and the production temperature is about $60^{\circ}C$, so it is difficult to utilize it for industrial use. Therefore, in this study, we developed a steam heat pump (SGHP) which recovers the waste heat of process and generates steam at $120^{\circ}C$. The low-pressure refrigerant R245fa, considered to be an eco-friendly refrigerant, has been selected as the refrigerant for SGHP in this study since its Ozone Depletion Potential (ODP) is zero and the Global Warming Potential (GWP) is relatively low. A flash tank functioning as a phase separator was installed in the rear stage of the condenser, and the saturated water of high temperature was decompressed to generate steam. It was started at the initial temperature of $70^{\circ}C$, and it was confirmed that $120^{\circ}C$ steam was produced after the system stabilized. We have conducted experiments by modifying the system, and ultimately achieved a heating capacity of 101.4 kW and a COP of 3.05.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.211-221
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• 2017

Ellipsodially referenced survey (ERS) is considered as one of the challenging issues in the hydrographic surveys due to the fact that the bathymetric data collected by this technique can be readily transformed either to the geodetic or the chart datum by application of some geoscientific models. Global Navigation Satellite Systems (GNSS) is a preferred technique to determine the ellipsoidal height of a vessel reference point (RP) because it provides cost-effective and unprecedentedly accurate positioning solutions. Especially, the GNSS-derived heights include heave and dynamic draft of a vessel, so as for the reduced bathymetric solutions to be potentially free from these corrections. Although over the last few decades, differential GNSS (DGNSS) has been widely adopted in the bathymetric surveys, it only provides limited accuracy of the vertical component. This technical barrier can be effectively overcome by adopting the so-called GNSS carrier phase (CPH) based techniques, enhancing accuracy of the height solution up to few centimeters. From the positioning algorithm standpoint, the CPH-based techniques are categorized under absolute and relative positioning in post-processing mode; the former is precise point positioning (PPP) correcting errors by the global or regional models, the latter is post-processed kinematic positioning (PPK) that uses the differencing technique to common error sources between two receivers. This study has focused on assessment of achievable accuracy of the ellipsoidal heights obtained from these CPH-based techniques with a view to their applications to hydrographic surveys where project area is, especially, few tens to hundreds kilometers away from the shore. Some field trials have been designed and performed so as to collect GNSS observables on static and kinematic mode. In this paper, details of these tests and processed results are presented and discussed.

• Clean Technology
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• v.19 no.3
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• pp.243-248
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• 2013

Thermally conductive materials are widely used in various applications where effective heat dissipation is required. Graphene shows high potential for various uses owing to high electrical conductivity, good mechanical strength, and high thermal conductivity. Generally previous works used organic solvents are generally used for the dispersion of graphene in fabrication procedure. In order to achieve clean fabrication it is required to use water media. In this study, we fabricated graphene attached poly(methyl methacrylate) (PMMA) microsphere via microfluidic method. With the aid of surfactant, graphene was well dispersed in water which was used as continuous flow. Thermal conductivity was improved with the small amount of graphene addition and this indicate potential use of this system for thermally conductive composite material.

• Journal of Acupuncture Research
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• v.18 no.1
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• pp.129-145
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• 2001

Objectives : To characterize the antitumorigenic potential of three representative bee venom components, Melittin, Apamin, and Phospholipase A2, their effects on cell proliferation and apotosis of the human melanoma cell line SK-MEL-2 were analyzed using molecular biological approaches. Methodes & Results : To determine the doses of the drugs that do not induce cytotoxic damage to this cell line, cell viability was examined by MTT assay. While SK-MEL-2 cells treated with 0.5 - 2.0㎍/㎖ of each drug showed no recognizable cytotoxic effect, marked reductions of cell viability were detected at concentrations over 5.0㎍/㎖. [3H]thymidine incorporation assay for cell proliferation demonstrated that DNA replication of SK-MEL-2 cells is inhibited by Apamin and Phospholipase A2 in a dose-dependent manner. Consistent with this result, the cells were accumulated at the G1 phase of the cell cycle after treatment with Apamin and Phospholipase A2, whereas no detectable change in cell proliferation was identified by Melittin treatment. In addition, tryphan blue exclusion and flow cytometric analyses showed that all of these drugs can trigger apoptotic cell death of SK-MEL-2, suggesting that Melittin, Apamin, and Phospholipase A2 have antitumorigenic potential through the suppression of cell growth and/or induction of apoptosis. Qantitative RT-PCR analysis revealed that Apamin and Phospholipase A2 inhibit expression of growth-promoting genes such as c-Jun, c-Fos, and Cyciin D1. Furthermore, Phospholipase A2 induced tumor suppressors p53 and p21/Wafl. In addition, all three drugs were found to activate expression of a representative apoptosis-inducing gene Bax while expression of apoptosis-suppressing Bcl-2 and Bcl-XL genes was not changed. Taken together, this study strongly suggests that Metittin, Apamin, and Phosphalipase A2 may have antitumorigenic activities, which are associated with its growth-inhibiting and/or apoptosis-inducing potentials.