Showing papers by "Chonbuk National University published in 2006"

An improved hydrophilicity via electrospinning for enhanced cell attachment and proliferation.

Abstract: The wettability of electrospun poly(epsilon-caprolactone) (PCL) mats was improved by co-electrospinning with poly(vinyl alcohol) (PVA), by double-spinneret electrospinning method. The improved hydrophilicity of the hybrid PCL/PVA mats was confirmed by water contact angle measurement. The in vitro cell attachment on the hydrophobic PCL and hydrophilically modified PCL/PVA mats was compared by culture studies using human prostate epithelial cells (HPECs). The stability of water-soluble PVA component in the electrospun PCL/PVA mats was checked by thermogravimetric analysis and intensity of fluorescence material after immersion in water for 7 days. The images from scanning electron microscopy, field emission scanning electron microscopy, and optical microscopy showed that the attachment and proliferation rate of HPECs were improved by introducing PVA into the electrospun PCL mats.

Inhibition of phosphoinositide 3-kinase δ attenuates allergic airway inflammation and hyperresponsiveness in murine asthma model

Abstract: P110δ phosphoinositide 3-kinase (PI3K) plays a pivotal role in the recruitment and activation of certain inflammatory cells Recent findings revealed that the activity of p110δ also contributes to allergen-IgE-induced mast cell activation and vascular permeability We investigated the role of p110δ in allergic airway inflammation and hyperresponsiveness using IC87114, a selective p110δ inhibitor, in a mouse asthma model BALB/c mice were sensitized with OVA and, upon OVA aerosol challenge, developed airway eosinophilia, mucus hypersecretion, elevation in cytokine and chemokine levels, up-regulation of ICAM-1 and VCAM-1 expression, and airway hyperresponsiveness Intratracheal administration of IC87114 significantly (P<005) attenuated OVA-induced influx into lungs of total leukocytes, eosinophils, neutrophils, and lymphocytes, as well as levels of IL-4, IL-5, IL-13, and RANTES in a dose-dependent manner IC87114 also significantly (P<005) reduced the serum levels of total IgE and OVA-specific IgE and LTC

Supersymmetry parameter analysis : SPA convention and project

Abstract: High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e(+)e(-) linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.

Doxorubicin-induced reactive oxygen species generation and intracellular Ca2+ increase are reciprocally modulated in rat cardiomyocytes.

Abstract: Doxorubicin (DOX) is one of the most potent anticancer drugs and induces acute cardiac arrhythmias and chronic cumulative cardiomyopathy. Though DOX-induced cardiotoxicity is known to be caused mainly by ROS generation, a disturbance of Ca2+ homeostasis is also implicated one of the cardiotoxic mechanisms. In this study, a molecular basis of DOX-induced modulation of intracellular Ca2+ concentration ([Ca2+]i) was investigated. Treatment of adult rat cardiomyocytes with DOX increased [Ca2+]i irrespectively of extracellular Ca2+, indicating DOX-mediated Ca2+ release from intracellular Ca2+ stores. The DOX-induced Ca2+ increase was slowly processed and sustained. The Ca2+ increase was inhibited by pretreatment with a sarcoplasmic reticulum (SR) Ca2+ channel blocker, ryanodine or dantrolene, and an antioxidant, alpha-lipoic acid or alpha-tocopherol. DOX-induced ROS generation was observed immediately after DOX treatment and increased in a time-dependent manner. The ROS production was significantly reduced by the pretreatment of the SR Ca2+ channel blockers and the antioxidants. Moreover, DOX-mediated activation of caspase-3 was significantly inhibited by the Ca2+ channel blockers and a-lipoic acid but not a-tocopherol. In addition, cotreatment of ryanodine with alpha-lipoic acid resulted in further inhibition of the casapse-3 activity. These results demonstrate that DOX-mediated ROS opens ryanodine receptor, resulting in an increase in [Ca2+]i and that the increased [Ca2+]i induces ROS production. These observations also suggest that DOX/ROS-induced increase of [Ca2+]i plays a critical role in damage of cardiomyocytes.

ZnO nanosheet networks and hexagonal nanodiscs grown on silicon substrate: growth mechanism and structural and optical properties

Abstract: Two-dimensional ZnO nanosheet networks composed of many thin and uniform hexagonal-shaped ZnO nanosheets and ZnO nanodiscs were prepared in a large scale on silicon substrate through thermal evaporation using ZnCl2 and O2 as source materials for Zn and oxygen, respectively, without the use of metal catalysts or additives Detailed structural studies indicated that the synthesized products are single crystalline with wurtzite hexagonal structure Raman scattering of the synthesized products confirmed that the as-grown structures have good crystal quality with a hexagonal wurtzite phase Room temperature photoluminescence spectra showed a strong green band with a suppressed UV emission from the ZnO nanosheet networks, but on the other hand a dominant and strong near band edge emission with a much suppressed deep level emission was observed in the nanodiscs The growth mechanism of these structures is also discussed in detail

Structural and optical properties of single-crystalline ZnO nanorods grown on silicon by thermal evaporation.

Abstract: The growth of perfectly hexagonal-shaped ZnO nanorods, with Zn-terminated (0001) facets bounded with surfaces, has been performed on nickel-coated Si(100) substrate via thermal evaporation using metallic zinc powder and oxygen. Detailed structural investigations confirmed that the synthesized nanorods are single crystalline with the wurtzite hexagonal phase and preferentially grow along the c-axis direction. Raman spectra of the as-grown ZnO nanorods showed an optical-phonon E2 mode at 438?cm?1, indicating that as-grown nanostructures are in good crystallinity with the wurtzite hexagonal phase. The ZnO nanorods were found to show strong band edge emission with very weak or no deep-level emission, as shown by photoluminescence measurements. The clear observation of free excitons at low temperatures (13?50?K) indicates that the as-grown ZnO nanorods are of high quality.

Synthesis and Characterization of Ultrahigh Crystalline TiO2 Nanotubes

Abstract: Ultrahigh crystalline TiO2 nanotubes were synthesized by hydrogen peroxide treatment of very low crystalline titania nanotubes (TiNT-as prepared), which were prepared with synthesized TiO2 nanoparticles by hydrothermal methods in an aqueous NaOH solution. Thus, prepared ultrahigh crystalline TiO2 nanotubes (TiNT-H2O2) showed comparable crystallinity with high crystalline TiO2 nanoparticles. The details of nanotubular structures were elucidated by high resolution-transmission electron microscopy (HR-TEM), field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis in transmission electron microscopy (TEM-EDX), X-ray diffraction (XRD), photoluminescence (PL), and BET surface area. TiNT-H2O2 was found to be a multiwalled anatase phase only with an average outer diameter of ∼8 nm and an inner diameter of ∼5 nm and grown along the [001] direction to 500−700 nm long with an interlayer fringe distance of ca. 0.78 nm. The photocatalytic activity of TiNT-H2O2 was about 2-fold higher than...

Wound healing effect of silk fibroin/alginate-blended sponge in full thickness skin defect of rat

Abstract: Silk fibroin (SF) and alginate (AA) have been proved to be invaluable natural materials in the field of biomedical engineering. This study was designed to compare the wound healing effect of SF, AA and SF/AA-blended sponge (SF/AA) with clinically used Nu GauzeTM (CONT) in a rat full thickness wound model. Two circular skin wounds on the back of rat were covered with either of CONT, SF, AA or SF/AA. On the postoperative days of 3, 7, 10 and 14, residual wound area was calculated, and skin wound tissues were biopsied to measure the area of regenerated epithelium and collagen deposition as well as the number of proliferating cell nuclear antigen (PCNA)-immunoreactive cells. Half healing time (HT50) of SF/AA was dramatically reduced as compared with that of SF, AA or CONT. Furthermore, SF/AA significantly increased the size of re-epithelialization and the number of PCNA positive cells, whereas the effect of SF/AA on collagen deposition was not significantly different as compared with that of SF or AA. These results demonstrate that the wound healing effect of SF/AA is the best among other treatments including SF and AA, and this synergic effect is mediated by re-epithelialization via rapid proliferation of epithelial cell.

Synthesis of nickel oxide nanoparticles using nickel acetate and poly(vinyl acetate) precursor

Abstract: Cubic nickel oxide (NiO) nanoparticles with uniform size around 40–50 nm and well dispersion have been synthesized using a mixture of nickel acetate and poly(vinyl acetate) (PVAc) as precursor followed by heat treatment at 723 K. The structure, morphology and crystalline phase of the nickel oxide nanocrystals have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum, UV–visible absorption spectrum and FT-IR. TEM images showed that the nickel oxide nanoparticles have hexagonal structure with uniform size distribution around 40–50 nm. Phase pure, cubic nickel oxide formation was identified from the XRD data.

Investigation of a Single Pd Nanowire for Use as a Hydrogen Sensor

Abstract: Interest in nanowire technology has grown significantly over the past several years, due to their potentially broad applications in optics, electronics, and sensors (e.g., resonators, molecular detection, nanoconnectors, biosensors, and gas sensors). Due to their small size, sensitivity, real-time detection, and ultra-low power demands, nanowire sensors are being investigated for detection of a wide range of chemical and biochemical species. The techniques used to fabricate these sensors include laser ablation cluster formation, focused ion-beam etching of electrodes to create a small gap ( 100 nm), use of ion-track membranes, use of alumina templates, and electrochemical step-edge decoration. These techniques have drawbacks of limited controllability and manufacturability, therefore reliable and controllable nanowire fabrication remains a significant challenge. We have previously reported a method of electrodepositing Pd wires with micrometer diameters and conducting polymer nanowires of polyaniline and polypyrrole with diameters of 100 nm. In this work, single Pd nanowires are fabricated by electrodeposition in electrolyte channels patterned with electron-beam lithography, and hydrogen sensing is demonstrated. This fabrication technique can produce nanowires with controlled dimensions, positions, alignments, and chemical compositions, and potentially enables the use of a wide range of materials for creating arrays of singlenanowire sensors. Additionally, the growth of nanowires using this technique would allow for easy integration with existing silicon technology. Figure 1 shows SEM images of typical electrodeposited nanowires between electrodes. The magnified image in Figure 1b shows a single Pd nanowire with a diameter ranging from 70 to 85 nm. An EDS (energy dispersive spectroscopy) elemental analysis detected only Pd metal in the nanowire.

Does Seed Priming Induce Changes in the Levels of Some Endogenous Plant Hormones in Hexaploid Wheat Plants Under Salt Stress

Abstract: In order to assess whether salt tolerance could be improved in spring wheat (Triticum aestivum L.), the present study was performed by soaking the seeds of two cultivars, namely MH-97 (salt sensitive) and Inqlab-91 (salt tolerant), for 12 h in distilled water or 100 mol/m3 CaCl2, KCl, or NaCl. Primed seeds from each treatment group and non-primed seeds were sown in a field in which NaCl salinity of 15 dS/m was developed. Priming of seeds with CaCl2, followed by priming with KCl and NaCl, was found to be effective in alleviating the adverse effects of salt stress on both wheat cultivars in terms of shoot fresh and dry weights and grain yield. Priming with CaCl2 alleviated the adverse effects of salt stress on hormonal balance in plants of both cultivars. In MH-97 plants, CaCl2 pretreatment considerably reduced leaf abscisic acid (ABA) concentrations and increased leaf free salicylic acid (SA) concentrations under both saline and non-saline conditions. In contrast, in the Inqlab-91 plant, CaCl2 increased free indoleacetic acid (IAA) and indolebutyric acid (IBA) content. However, priming of seeds with CaCl2 did not alter free polyamine levels in either cultivar, although spermidine levels were considerably lower in plants raised from seeds treated with CaCl2 for both cultivars under saline conditions. Priming with KCl increased growth in Inqlab-91 plants, but not in MH-97 plants, under saline conditions. The salinity induced reduction in auxins (IAA and IBA) was alleviated by NaCl priming in both cultivars under saline conditions. However, NaCl increased leaf free ABA content and lowered leaf SA and putrescine levels in Inqlab-91 plants under saline conditions. In conclusion, although all three priming agents (i.e. CaCl2, KCl, and NaCl) were effective in alleviating the adverse effects of salt stress on wheat plants, their effects on altering the levels of different plant hormones were different in the two cultivars. (Managing editor: Ping He)

Tick-Borne Rickettsial Pathogens in Ticks and Small Mammals in Korea

Abstract: In order to investigate the prevalence of tick-borne infectious agents among ticks, ticks comprising five species from two genera (Hemaphysalis spp. and Ixodes spp.) were screened using molecular techniques. Ticks (3,135) were collected from small wild-caught mammals or by dragging/flagging in the Republic of Korea (ROK) and were pooled into a total of 1,638 samples (1 to 27 ticks per pool). From the 1,638 tick samples, species-specific fragments of Anaplasma phagocytophilum (1 sample), Anaplasma platys (52 samples), Ehrlichia chaffeensis (29 samples), Ehrlichia ewingii (2 samples), Ehrlichia canis (18 samples), and Rickettsia rickettsii (28 samples) were amplified by PCR assay. Twenty-one pooled and individual tick samples had mixed infections of two (15 samples) or three (6 samples) pathogens. In addition, 424 spleen samples from small captured mammals (389 rodents, 33 insectivores, and 2 weasels) were screened for selected zoonotic pathogens. Species-specific DNA fragments of A. phagocytophilum (110 samples), A. platys (68 samples), E. chaffeensis (8 samples), E. ewingii (26 samples), E. canis (51 samples), and Rickettsia sp. (22 samples) were amplified by PCR assay. One hundred thirty small mammals had single infections, while 4, 14, and 21 striped field mice (Apodemus agrarius) had mixed infections of four, three, and two pathogens, respectively. Phylogenetic analysis based on nucleotide sequence comparison also revealed that Korean strains of E. chaffeensis clustered closely with those from China and the United States, while the Rickettsia (rOmpA) sequences clustered within a clade together with a Chinese strain. These results suggest that these agents should be considered in differential diagnosis while examining cases of acute febrile illnesses in humans as well as animals in the ROK.

Hypoxia Enhances Lysophosphatidic Acid Responsiveness in Ovarian Cancer Cells and Lysophosphatidic Acid Induces Ovarian Tumor Metastasis In vivo

Abstract: Lysophosphatidic acid (LPA) is elevated in ascites of ovarian cancer patients and stimulates growth and other activities of ovarian cancer cells in vitro . Tissue hypoxia is a critical factor for tumor aggressiveness and metastasis in cancers. We tested whether the ascites of ovarian cancer is hypoxic and whether hypoxia influences the effects of LPA on ovarian cancer cells. We found that ovarian ascitic fluids were hypoxic in vivo . Enhanced cellular responsiveness to LPA, including migration and/or invasion of ovarian cancer cells, was observed under hypoxic conditions. This enhancement could be completely blocked by geldanamycin or a small interfering RNA targeting hypoxia-inducible factor 1α (HIF1α). LPA-induced cell migration required cytosolic phospholipase A 2 (cPLA 2 ) and LPA stimulates cPLA 2 phosphorylation in a HIF1α-dependent manner under hypoxia conditions. Furthermore, we show for the first time that exogenous LPA enhances tumor metastasis in an orthotopic ovarian cancer model and HIFα expression in tumors. 17-Dimethylaminoethylamino-17-demethoxygeldanamycin (an inhibitor of the heat shock protein 90) effectively blocked LPA-induced tumor metastasis in vivo. Together, our data indicate that hypoxic conditions are likely to be pathologically important for ovarian cancer development. HIF1α plays a critical role in enhancing and/or sensitizing the role of LPA on cell migration and invasion under hypoxic conditions, where cPLA 2 is required for LPA-induced cell migration. (Cancer Res 2006; 66(16): 7983-90)

Sirolimus-Eluting Stent Versus Paclitaxel-Eluting Stent for Patients With Long Coronary Artery Disease

Abstract: Background— Outcomes remain relatively unfavorable for stent-based coronary intervention of lesions with long diseased segments. This study compared sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) for long coronary lesions. Methods and Results— The present randomized, multicenter, prospective study compared the use of long (≥32 mm) SES with PES in 500 patients with long (≥25 mm) native coronary lesions. The primary end point of the trial was the rate of binary in-segment restenosis according to follow-up angiography at 6 months. The SES and PES groups had similar baseline characteristics. Lesion length was 33.9±11.6 mm in the SES group and 34.5±12.6 mm in the PES group (P=0.527). The in-segment binary restenosis rate was significantly lower in the SES group than in the PES group (3.3% versus 14.6%; relative risk 0.23; P<0.001). In-stent late loss of lumen diameter was 0.09±0.37 mm in the SES group and 0.45±0.55 mm in the PES group (P<0.001). In patients with restenoses, a pattern of foc...

Characterization of the pectic polysaccharides from pumpkin peel

Abstract: The alcohol insoluble polysaccharide (AIP) was extracted from pumpkin ( Cucurbita moschata Duch) peels, and they were fractionated subsequently into water soluble pectic substance (WSP), EDTA soluble pectic substance (ESP) and alkali soluble pectic substance (ASP) fractions. ASP fraction (24.78 and 46.07 g/100 g) contained the highest total sugar and uronic acid contents compared with WSP (17.78 and 4.89 g/100 g) and ESP (18.43 and 23.99 g/100 g) fractions. WSP fraction had 2 peaks with a small one close to 205 kDa and a major one close to 13 kDa, while ESP and ASP fractions had 3 peaks with higher molecular weight distributions than WSP. The sugar peaks in the ion exchange chromatography were detected in a low concentration of ammonium acetate buffer, but uronic acid peaks were detected in a high concentration of ammonium acetate buffer and 0.2 mol/l NaOH. ESP had higher glucose retardation effect than that of WSP and ASP, while WSP and ASP had higher bile acid retardation effects than that of ESP. AIP fractions activated growth in Lactobacillus brevis, Bifidobacterium bifidum and Bifidobacterium longum , whereas they inhibited growth in Escherichia coli and Clostridium perfringens in RCM medium.