Ju Hyun Park

Korea University, Sŏul, Seoul, South Korea

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Publications (68)137.13 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The importance of anti-apoptosis in mammalian cell culture has been widely recognized. We reported previously that expression of Bombyx mori 30 K genes in Chinese hamster ovary (CHO) cells increases recombinant protein production by inhibiting apoptosis and enhancing specific productivity. However, previous studies have shown expression of the anti-apoptotic 30Kc6 protein as inclusion bodies in Escherichia coli. 30Kc19 protein, another silkworm hemolymph protein, has cell-penetrating and recombinant protein productivity-improving properties, and we found that it improves soluble expression of its partner. In this study, we fused 30Kc6 with 30Kc19 as an expression partner to express a soluble fused protein and to deliver the protein to cells. Supplementing the recombinant 30Kc19-30Kc6 fusion protein in cell culture medium increased viability, effectively penetrated the cells, and inhibited CHO cell apoptosis by 68%. Moreover, the mitochondrial membrane potential and ATP generation also increased by 50% and 33%, respectively. Erythropoietin (EPO) productivity increased by > 30% because of the anti-apoptotic effect and increased specific productivity. These results demonstrate the potential use of this fusion protein as a supplement in mammalian cell culture during production of biopharmaceutical proteins.
    PROCESS BIOCHEMISTRY 06/2015; 50(6). DOI:10.1016/j.procbio.2015.03.008
  • Jeong Yong Kwon, Ju Hyun Park, Tae Geun Kim
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    ABSTRACT: We propose a SiOxNy/AlN bilayer resistive switching random access memory scheme to eliminate crosstalk in a crossbar array structure. We demonstrated forming-free self-rectifying behaviors at an ultralow operating current (below 200 nA) by optimizing the current compliance and operating voltage. The set and reset voltages were reduced using a thin AlN layer, and the voltages' on/off ratio and rectifying ratio were as high as 80 and 102, respectively. In addition, the device showed an endurance of 103 dc cycles and a retention time over 105 s.
    Applied Physics Letters 06/2015; 106(22):223506. DOI:10.1063/1.4922252
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    ABSTRACT: This paper reports the bipolar resistive switching characteristics of TaNx-based resistive random access memory (ReRAM). The conduction mechanism is explained by formation and rupture of conductive filaments caused by migration of nitrogen ions and vacancies; this mechanism is in good agreement with either Ohmic conduction or the Poole-Frenkel emission model. The devices exhibit that the reset voltage varies from −0.82 V to −0.62 V, whereas the set voltage ranges from 1.01 V to 1.30 V for 120 DC sweep cycles. In terms of reliability, the devices exhibit good retention (>105 s) and pulse-switching endurance (>106 cycles) properties. These results indicate that TaNx-based ReRAM devices have a potential for future nonvolatile memory devices.
    Applied Physics Letters 05/2015; 106(20):203101. DOI:10.1063/1.4921349
  • The Journal of Urology 04/2015; 193(4):e136. DOI:10.1016/j.juro.2015.02.341
  • The Journal of Urology 04/2015; 193(4):e139. DOI:10.1016/j.juro.2015.02.347
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    ABSTRACT: In this study, nitrogen-doped WOx thin films are investigated for the improvement of resistive switching (RS) properties. Compared to WOx thin films, nitrogen-doped WOx thin films exhibit a higher on/off current ratio (a separation of ~ 2 orders of magnitude), better endurance (> 100 cycles), narrower current dispersion, and longer retention characteristics (> 104 s). Electrical measurements, X-ray Diffraction, and X-ray photoelectron spectroscopy demonstrate that nitrogen in WOx:N thin films forms WN nanoclusters and Wx (O, N) phases, which are beneficial to improve the RS properties in WOx thin films; WN nanoclusters can locally enhance the electric field to form stable conductive filament while Wx (O, N) phases can suppress random migrations of oxygen ions (O2 −), leading to stable RS characteristics. Our findings suggest that nitrogen doping method can lead further optimization of the RS characteristics in WOx thin films.
    Thin Solid Films 03/2015; 583:81-85. DOI:10.1016/j.tsf.2015.03.049
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    ABSTRACT: This study was conducted to prevent flower bud abortion in forcing culture of herbaceous peony. When dormant rootstocks of Paeonia lactiflora 'Taebaek' were subjected to dormancy-breaking treatment (0°C for 6 weeks) in November, this could hasten flowering in early spring. However plants chilled in August, September, or October produced abnormal flowers or resulted in flower bud abortion. To prevent flower bud abortion, we placed the dormant rootstocks at five pre-chilling treatments for 2 weeks in mid-September and October. The treatment conditions were 0°C for 2 weeks (C0, control), natural chilling in an open field for 2 weeks (NT), pre-chilling at 15°C for 2 weeks (P15), 15°C for 1 week → 10°C for 1 week (P15 → 10), and pre-chilling at 10°C for 2 weeks (P10). After these pre-chilling treatments, all of the plants were placed under a cold regime of 0°C for 6 weeks in order to break dormancy. In the C0 and NT treatments, a great numbers of flower buds were aborted from their stems. On the other hand, the P15 → 10 and P10 treatments increased to 74.7 and 81.0% for flowering, respectively. Pre-cooling treatment accelerated the growth of flower buds compared to the C0 or NT treatments. To promote blooming in the autumn season, rootstocks were also placed into three treatments (C0, NT, and P10) in early July. While the C0 and NT treatment were unable to produce flowering at all, the treatment P10 induced more than 80% flowering of plants. From these results, pre-chilling at treatment 10°C for 2 weeks was recommended as the optimum treatment to promote flowering without flower bud abortion in forcing culture for winter or autumn flowering.
    Horticulture, Environment and Biotechnology 02/2015; 56(1):1-8. DOI:10.1007/s13580-015-0050-0
  • Dong Su Jeon, Ju Hyun Park, Tae Geun Kim
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    ABSTRACT: In this study, NiN-based resistive switching (RS) random access memory was doped with various concentrations of oxygen, and its uniform set/reset operation and current levels were examined. As compared with undoped RS layers, RS layers deposited with an oxygen flow rate of 5 sccm were more uniform and exhibited higher on/off ratios by forming oxy-nitride. In contrast, RS layers deposited with oxygen flow rates less than 5 sccm showed poor performance due to oxygen acting as a defect. The authors demonstrated that the oxygen doping process can improve the RS characteristics of NiN films and help clarify the RS phenomena associated with these films. (C) 2014 American Vacuum Society.
    Journal of vacuum science & technology. B, Microelectronics and nanometer structures: processing, measurement, and phenomena: an official journal of the American Vacuum Society 01/2015; 33(1). DOI:10.1116/1.4904209
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    ABSTRACT: Seasonality, an individual trait of seasonal variations in mood and behavior, has received clinical attention for its association with mood disorders. This study aimed to explore the prevalence, specific manifestation, and associated individual and climatic factors of seasonality in the non-elderly adult population. Five hundred fifty-two participants [male n=220; female n=332; mean age 34.92years, standard deviation (SD) 10.18] with no psychiatric history were recruited from the Seoul metropolitan area (37°33'58.87″N 126°58'40.63″E). Seasonality was evaluated using the Seasonal Pattern Assessment Questionnaire. Climatic variables used in analyses were averaged over recent 5years (from 2008 to 2013) on a monthly basis. The mean global seasonality score (GSS) was 5.53 (SD 3.91), and 16.2% (n=89) of participants had seasonal affective disorder (SAD) or sub-SAD. The "feeling worst" month in most of the participants with significant seasonality were winter (41.6%) or summer (38.2%). Socio-demographic factors including age and sex were not related to the seasonality. Decreased sunlight amount and diurnal temperature range in a given and previous month, and increased humidity in a previous month showed significant associations with the percentage of participants with the worst mood. The most frequently reported symptom related to seasonality was 'changes in energy level'. Specific manifestations were not significantly different between the winter type and the summer type. The summer and winter type seasonality in the non-clinical adult population did not differ in terms of behavioral manifestations. Decreased sunlight amount, diurnal temperature range, and increased humidity appeared to be major climatic factors associated with seasonality. Copyright © 2014 Elsevier Inc. All rights reserved.
    Comprehensive Psychiatry 10/2014; 57. DOI:10.1016/j.comppsych.2014.10.014
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    ABSTRACT: In previous studies, 30Kc19, a lipoprotein in silkworm hemolymph, enhanced productivity and glycosylation by expression of a 30Kc19 gene or supplementation with a recombinant 30Kc19 protein. Additionally, 30Kc19 exhibited enzyme-stabilizing and cell-penetrating abilities in vitro. In this study, we hypothesized that supplemented 30Kc19 penetrated into the cell and enhanced the stability of the cellular enzyme. We investigated this using in vitro and cellular assessments. The activity of sialyltransferase (ST) and isolated mitochondrial complex I/III was enhanced with 30Kc19 in dose-dependent manner while initial reaction rate was unchanged, suggesting that 30Kc19 enhanced enzyme stability rather than specific activity. For intracellular enzyme activity assessment, ST activity inside erythropoietin (EPO)-producing Chinese hamster ovary (CHO) cells increased more than 25 % and mitochondrial complex II activity in HeLa cells increased more than 50 % with 30Kc19. The increase in intracellular ST activity resulted in an increase in sialic acid content of glycoproteins produced in CHO cells supplemented with 30Kc19. Similarly, enhanced mitochondrial complex activity increased mitochondrial membrane potential and ATP production in HeLa cells with 30Kc19 by over 50 %. Because 30Kc19 stabilized intracellular enzymes for glycosylation and enhanced protein productivity with supplementation in the culture medium, we expect that 30Kc19 can be a valuable tool for effective industrial recombinant protein production.
    Applied Microbiology and Biotechnology 09/2014; 99(5). DOI:10.1007/s00253-014-6045-4
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    ABSTRACT: Cell-penetrating peptides (CPPs) or protein transduction domains (PTDs) have attracted increasing attention due to their high potential to deliver various, otherwise impermeable, bioactive agents, such as drugs and proteins across cell membranes. A number of CPPs have been discovered since then. Recently, 30Kc19 protein has attracted attention because it was the first cell-penetrating protein that has been found in insect hemolymph. Here, we report a cell-penetrating peptide derived from 30Kc19 protein, VVNKLIRNNKMNC, which efficiently penetrates cells when supplemented to medium for mammalian cell culture. Moreover, like other CPPs, this “Pep-c19” also efficiently delivered cell-impermeable cargo proteins, such as green fluorescent protein (GFP) into cells. In addition to the in vitro system, Pep-c19 exhibited the cell-penetrating property in vivo. When Pep-c19 was intraperitoneally injected into mice, Pep-c19 successfully delivered cargo proteins into various organ tissues with higher efficiency than the 30Kc19 protein itself, and without toxicity. Our data demonstrates that Pep-c19 has a great potential as a cell-penetrating peptide that can be used as a therapeutic tool to efficiently deliver different cell-impermeable cargo molecules into the tissues of various organs.
    PROCESS BIOCHEMISTRY 09/2014; 49(9). DOI:10.1016/j.procbio.2014.05.008
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    ABSTRACT: Recently, the recombinant 30Kc19 protein, originating from silkworm hemolymph of Bombyx mori has attracted attention due to its cell-penetrating property and potential application as a protein delivery system. However, this observation of penetration across cell membrane has raised questions concerning the interaction of the protein-lipid bilayer. Here, we report a dimerization propensity of the 30Kc19 protein in the presence of amphiphilic moieties; SDS or phospholipid. Native PAGE showed that the 30Kc19 monomer formed a dimer when SDS or phospholipid was present. In the GST pull-down assay, supplementation of the 30Kc19 protein to mammalian cell culture medium showed dimerization and penetration; due to phospholipids at the cell membrane, the main components of the lipid bilayer. Mutagenesis was performed, and penetration was observed by 30Kc19 C76A and not 30Kc19 C57A, which meant that the presence of cysteine at position 57 (Cys-57) is involved in dimerization of the 30Kc19 at the cell membrane during penetration. We anticipate application of the native 30Kc19 protein with high cell-penetrating efficiency for delivery of cargos to various cell types. The intracellular cargo delivery using the 30Kc19 protein is a non-virus derived (e.g. TAT) delivery method, which can open up new approaches for the delivery of therapeutics in bioindustries, such as pharma- and cosmeceuticals.
    Biotechnology Journal 08/2014; DOI:10.1002/biot.201400253
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    ABSTRACT: a b s t r a c t In this study, we investigate the effect of the roughness height of bottom electrodes (BEs) on the resistive switching properties of a 1 Â 1 platinum/nickel nitride/nickel (Pt/NiN/Ni) capacitor crossbar array (CBA) resistive random access memory (ReRAM) cell. The thickness of the rough surface is varied from 40 nm to 80 nm. In the resistive switching tests, the set voltage in the current–voltage (I–V) curves is reduced by using a rough surface (RS) BE in the Si wafer, and the reset current is reduced by increasing the surface roughness height of the Si wafer. On the other hand, there is a reduction in V SET/RESET and I SET/RESET variations in the I–V curves over 100 repetitive switching cycles when a surface roughness of 40 nm is employed. Further, for the CBA ReRAM, the current is the most stable when using the 40 nm-thick RS Si wafer at the high-resistance state and low-resistance state for 300,000 s in the retention test. These results show that use of the roughness substrate in the CBA ReRAM structure is effective in reducing var-iations in operating voltage and current. Ó 2014 Published by Elsevier B.V.
    Microelectronic Engineering 08/2014; 126:169-172. DOI:10.1016/j.mee.2014.07.018
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    ABSTRACT: The foliage of variegated Solomon's seal is excellent in cut flower arrangements. However, it has a restricted marketing period because the harvesting is limited in spring and summer. The increased interest requires the year-round production, thus techniques for dormancy breaking and forcing without low temperature treatment is needed. Therefore, experiments were conducted to determine whether gibberellic acid (GA) could break dormancy in variegated Solomon's seal. The sprouting of dormant bud did not occur throughout the experiment when GA3 400 mg・L -1 was applied to dormant rhizomes as a soil drench. However, when plants were treated with a GA drench after scratch with razor blade or were given direct injection of GA, percent sprouting was increased up to 100 or 83.3%, respectively. However, because treatments with razor or syringe may damage internal organs, we tested another method, scarifying the rhizomes with sodium hypochlorite (NaOCl). Rhizome scarification with 4% NaOCl for 6 or 24 hours followed by drench of GA3 400 mg・L -1 increased the dormancy breaking percentage to 70 or 86.7%, respectively. Moreover, scarified and GA-treated rhizomes produced more leaves than untreated or GA-soil drenched plants in the glasshouse. These results showed the possibility of year-round production of variegated Solomon's seal foliage with rhizome scarification and GA treatments.
    Wonye kwahak kisulchi = Korean journal of horticultural science and technology / 06/2014; 32(3):296-302. DOI:10.7235/hort.2014.13146
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    ABSTRACT: The metal nanocrystals (NCs) embedded-NiN-based resistive random access memory cells are demonstrated using several metal NCs (i.e., Pt, Ni, and Ti) with different physical parameters in order to investigate the metal NC's dependence on resistive switching (RS) characteristics. First, depending on the electronegativity of metal, the size of metal NCs is determined and this affects the operating current of memory cells. If metal NCs with high electronegativity are incorporated, the size of the NCs is reduced; hence, the operating current is reduced owing to the reduced density of the electric field around the metal NCs. Second, the potential wells are formed by the difference of work function between the metal NCs and active layer, and the barrier height of the potential wells affects the level of operating voltage as well as the conduction mechanism of metal NCs embedded memory cells. Therefore, by understanding these correlations between the active layer and embedded metal NCs, we can optimize the RS properties of metal NCs embedded memory cells as well as predict their conduction mechanisms.
    Journal of Applied Physics 03/2014; 115(9):094305-094305-5. DOI:10.1063/1.4867639
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    ABSTRACT: The improvement of resistive switching (RS) phenomena of silicon-nitride (SiNx)-based resistive random access memory (ReRAM) cells through oxygen doping process was investigated. As a result, compared to un-doped SiNx films, the oxygen doped SiNx (SiNx:O2)-based ReRAM cells show a lower current (∼0.3 μA) level at a high resistance state and a smaller variation of operating voltage through the reduction of leakage current in the SiNx:O2 film by combining silicon dangling bonds and doped oxygen ions. Therefore, we believe that the oxygen doping process in SiNx films can effectively improve the RS characteristics of SiNx-based ReRAM cells. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
    physica status solidi (RRL) - Rapid Research Letters 03/2014; 8(3). DOI:10.1002/pssr.201308309
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    ABSTRACT: We demonstrate highly uniform resistive-switching (RS) characteristics of an SiN nanorod (NR) device fabricated by nanosphere lithography. In the RS experiments, variations in set and reset voltages for the SiN NR device are dramatically reduced to 0.2 V from 0.45 V in conventional SiN thin films. In addition, the resistance ratio (10 3) between set and reset states is larger and stably maintained without any degradation. As a result, in the resistive random access memory (RRAM) cells with a filament-based RS mechanism, the RS behavior of NR-based RS materials is more uniform than that of the conventional films as a result of reducing the number of conducting paths in the SiN layer.
    Applied Physics Express 01/2014; 7(2):024202. DOI:10.7567/APEX.7.024202
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    ABSTRACT: Nanoparticles have been widely used for delivering various chemical and biomolecular drugs, such as anti-cancer drugs and therapeutic proteins. Among nanoparticles, protein nanoparticles have advantages of non-cytotoxicity and biodegradability. In this study, a recombinant 30Kc19 protein was applied to human serum albumin (HSA) nanoparticles to enhance cellular uptake and stability of a nanoparticle cargo enzyme. The 30Kc19 protein, which originates from silkworm, has cell-penetrating and enzyme-stabilizing abilities. Therefore, 30Kc19-HSA nanoparticles were expected to enhance cellular uptake and stability of an enzyme loaded on the nanoparticles. Here, nanoparticles loaded with β-galactosidase were prepared using the desolvation method. The 30Kc19-HSA nanoparticles were uniformly spherical in shape, dispersed evenly in phosphate buffered saline and cell culture media, and released β-galactosidase in a sustained manner. The 30Kc19-HSA nanoparticles had negligible toxicity to animal cells and exhibited enhanced cellular uptake and intracellular stability of β-galactosidase in HeLa and HEK293 cells when compared with those of HSA nanoparticles. These results suggest that 30Kc19-HSA protein nanoparticles could be used as a versatile tool for drug delivery to various cells.
    Biomaterials 11/2013; 35(5). DOI:10.1016/j.biomaterials.2013.11.001
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    ABSTRACT: Silkworm hemolymph (SH) was found to exhibit anti-apoptotic activities in mammalian and insect cell systems. An anti-apoptotic mechanism of SH was investigated in a staurosporine-induced HeLa cell using flow cytometry, caspase assay, Immunoblot, and Immunochemistry. The addition of 5%SH to the medium resulted in lower intracellular activities of caspase-3 and caspase-9 after 0.6 mu M of staurosporine treatment; however, SH did not directly inhibit the activities of those enzymes. This suggests SH inhibits the event upstream of these caspase activation steps, such as mitochondrial level events. We found from Immunoblot and Immunochemistry that cytochrome c release from the mitochondria was blocked by SH. SH also inhibited Bax translocation to the mitochondria. On the contrary, SH did not block the apoptosis when Bax is not involved in promoting apoptosis. With these results, we propose that SH protects mitochondria from apoptosis signal via blocking Bax translocation, and the subsequent apoptotic events are then inhibited. The inhibition of apoptosis using SH and its components may lead to new approaches for the minimization of cell death during commercial animal cell cultures.
    PROCESS BIOCHEMISTRY 09/2013; 48(9):1375-1380. DOI:10.1016/j.procbio.2013.06.018
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    ABSTRACT: Psoriatic arthritis is a chronic inflammatory form of arthritis that is associated with psoriasis. A 54-yr-old male with chronic psoriatic temporomandibular joint arthritis and myofascial pain was treated using methotrexate and a myofascial pain protocol. Jaw pain improved after 3 weeks, however, tenderness to palpation of muscles remained. Comprehensive evaluation and multidisciplinary clinical treatment is required for the treatment of patients with psoriatic temporomandibular joint arthritis.
    06/2013; 29(2). DOI:10.14368/jdras.2013.29.2.203

Publication Stats

303 Citations
137.13 Total Impact Points

Institutions

  • 2014–2015
    • Korea University
      • Department of Electrical Engineering
      Sŏul, Seoul, South Korea
  • 2003–2015
    • Seoul National University
      • • Department of Plant Science
      • • Department of Chemical and Biological Engineering
      • • Department of Electrical and Computer Engineering
      Sŏul, Seoul, South Korea
  • 2007–2014
    • Sungkyunkwan University
      • Department of Radiology
      Sŏul, Seoul, South Korea
    • Soonchunhyang University
      • College of Medicine
      Onyang, South Chungcheong, South Korea
  • 2012
    • Jeju National University
      Tse-tsiu, Jeju-do, South Korea
    • Saint Mary's Hospital Center
      Montréal, Quebec, Canada
  • 2011
    • University of Ulsan
      Urusan, Ulsan, South Korea
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
    • Ulsan National Institute of Science and Technology
      Urusan, Ulsan, South Korea
  • 2009–2011
    • Sejong University
      • Faculty of Food Science and Technology
      Sŏul, Seoul, South Korea
    • Inje University
      Kŭmhae, Gyeongsangnam-do, South Korea
  • 2010
    • Korea University of Science and Technology
      Sŏul, Seoul, South Korea
    • Yonsei University
      • Department of Oral Medicine
      Seoul, Seoul, South Korea
    • Seoul National University Hospital
      • Department of Urology
      Seoul, Seoul, South Korea
  • 2008–2010
    • Chonnam National University
      • Department of Electrical, Electronic Communication and Computer Engineering
      Gwangju, Gwangju, South Korea
  • 2002–2008
    • Yeungnam University
      • • Department of Electrical Engineering
      • • Department of Electronic Engineering
      Gyeongsan, Gyeongsangbuk-do, South Korea