Showing papers by "Chonbuk National University published in 1996"

Genetically selected cardiomyocytes from differentiating embronic stem cells form stable intracardiac grafts.

Abstract: This study describes a simple approach to generate relatively pure cultures of cardiomyocytes from differentiating murine embryonic stem (ES) cells. A fusion gene consisting of the alpha-cardiac myosin heavy chain promoter and a cDNA encoding aminoglycoside phosphotransferase was stably transfected into pluripotent ES cells. The resulting cell lines were differentiated in vitro and subjected to G418 selection. Immunocytological and ultrastructural analyses demonstrated that the selected cardiomyocyte cultures (> 99% pure) were highly differentiated. G418 selected cardiomyocytes were tested for their ability to form grafts in the hearts of adult dystrophic mice. The fate of the engrafted cells was monitored by antidystrophin immunohistology, as well as by PCR analysis with primers specific for the myosin heavy chain-aminoglycoside phosphotransferase transgene. Both analyses revealed the presence of ES-derived cardiomyocyte grafts for as long as 7 wk after implantation, the latest time point analyzed. These studies indicate that a simple genetic manipulation can be used to select essentially pure cultures of cardiomyocytes from differentiating ES cells. Moreover, the resulting cardiomyocytes are suitable for the formation of intracardiac grafts. This selection approach should be applicable to all ES-derived cell lineages.

Observation of charge enhancement induced by graphite atomic vacancy: A comparative STM and AFM study.

Abstract: An atomic vacancy is produced on a graphite surface by bombarding it with low-energy (40-80 eV) beams of ${\mathrm{Ar}}^{+}$ ions, and its structure is examined by scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The atomic vacancy is imaged as a surface protrusion in STM, while it is transparent in AFM. These two contradictory results are explained by the vacancy-induced enhancement of the partial charge density of states at the carbon atoms near the vacancy. The charge enhancement can occur over tens of the surrounding carbon atoms for multiatom vacancy.

Self-Assembly of 1,2-Benzenedithiol on Gold and Silver: Fourier Transform Infrared Spectroscopy and Quartz Crystal Microbalance Study

Abstract: The adsorption of 1,2-benzenedithiol (1,2-BDT) in benzene on gold and silver surfaces has been investigated by infrared reflection−absorption (IRA) spectroscopy, quartz crystal microbalance (QCM), and ellipsometry The IRA spectral data were found to be consistent with those of QCM and ellipsometry On both metals, 1,2-BDT was chemisorbed by forming two metal−sulfur bonds after deprotonation Although monolayered film was formed exclusively on gold, multilayered film could also be formed on silver The orientation on gold changed little with respect to the surface coverage, but structural change from vertical to tilted orientation occurred on silver at the fractional surface coverage near 06 The tilt angles of benzene ring were estimated to be ca 51° on gold and 38° on silver with respect to the surface normal From the analysis of the IRA peak intensities, the free energy of adsorption, ΔGao, under submonolayer coverage limit was estimated to be −273 kJ/mol on gold and −396 kJ/mol on silver, suggest

Esophagorespiratory fistulae due to esophageal carcinoma: palliation with a covered Gianturco stent.

Abstract: PURPOSE: To evaluate therapeutic effects and complications of a covered Gianturco stent for esophagorespiratory fistulae. MATERIALS AND METHODS: Of 95 patients with esophageal carcinomas, 10 had esophagorespiratory fistulae and were treated with a silicone-covered Gianturco stent. The authors retrospectively assessed patients' food intake capacity and delayed problem of the stent. RESULTS: All fistulae were occluded without immediate complications. Two patients could swallow all foods; four, most foods; three soft foods; and one, only liquids. Clinical problems occurred between 1 and 24 weeks in four patients: reopened fistula (n = 1), recurrent fistula (n = 1) (both patients were successfully treated with another esophageal stent), and dyspnea (n = 2) due to tracheal compression by stent and tracheal invasion by tumor (one patient was treated with a tracheal stent). CONCLUSION: A silicone-covered modified Gianturco stent is effective for palliation of esophagorespiratory fistulae caused by esophageal can...

Kinetic role of a surfactant in island formation.

Abstract: Diffusion in the presence of a surfactant on islands is investigated using ab initio molecular dynamics. We introduce a double layer step on the Si(001) surface that emulates the ${311}$ facet of an island and show how the diffusion barrier varies with introduction of an Sb surfactant at the step edge. In contrast with the role of surfactants on a flat surface, where diffusion of adatoms is suppressed by site exchange, we find that the surfactant significantly reduces the Schwoebel barrier near the step edge such that island formation is severely suppressed and thus layer-by-layer growth is promoted. We show that the surfactant favors the step edge site and is replaced by adatoms via a pushing-out mechanism, thus repeating the step growth until the island is flattened.

Measurement of muon transfer from proton to triton and p p mu molecular formation in solid hydrogen

Abstract: An alternate approach was used to study the reactions of muonic atoms and molecules in solid layers of hydrogen isotopes. Muons stopped in a protium layer with a small admixture of tritium producing \ensuremath{\mu}p atoms. Muon transfer from a proton to a triton generated \ensuremath{\mu}t atoms, which were emitted into a deuterium layer. Subsequent epithermal dt\ensuremath{\mu} molecular formation followed by dt fusion gave a prompt signal for the \ensuremath{\mu}t emission. Fusion time spectra at various tritium concentrations were measured by detecting neutrons and \ensuremath{\alpha} particles and the \ensuremath{\mu}p disappearance rates were determined. The rates of \ensuremath{\mu}p\ensuremath{\rightarrow}\ensuremath{\mu}t transfer and pp\ensuremath{\mu} formation were measured to be ${\ensuremath{\lambda}}_{\mathit{pt}}$=[5.86\ifmmode\pm\else\textpm\fi{}(0.10${)}_{\mathit{stat}}$\ifmmode\pm\else\textpm\fi{}(0.15${)}_{\mathit{syst}}$${(}_{\mathrm{\ensuremath{-}}0}^{+0.30}$${)}_{\mathit{model}}$]\ifmmode\times\else\texttimes\fi{}${10}^{9}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and ${\ensuremath{\lambda}}_{\mathit{pp}\mathrm{\ensuremath{\mu}}}$=[3.21 \ifmmode\pm\else\textpm\fi{}(0.10${)}_{\mathit{stat}}$\ifmmode\pm\else\textpm\fi{}(0.14${)}_{\mathit{syst}}$${(}_{\mathrm{\ensuremath{-}}0.06}^{+0}$${)}_{\mathit{model}(}$]\ifmmode\times\else\texttimes\fi{}${10}^{6}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, respectively. Comparisons are made with the most recent theoretical values. \textcopyright{} 1996 The American Physical Society.

Pulmonary damage by Vibrio vulnificus cytolysin.

Abstract: Vibrio vulnificus is an estuarine bacterium that causes septicemia and serious wound infection. Cytolysin produced by V. vulnificus has been incriminated as one of the important virulence determinants of bacterial infection. Cytolysin (8 hemolytic units) given intravenously to mice via their tail veins caused severe hemoconcentration and lethality. Cytolysin treatment greatly increased pulmonary wet weight and vascular permeability as measured by (125)I-labeled albumin leakage without affecting those factors of other organs significantly. Blood neutrophils were markedly decreased in number after cytolysin injection, with a concomitant increase in the level of pulmonary myeloperoxidase activity, indicating that cytolysin-induced neutropenia might be due to pulmonary sequestration of neutrophils. By microscopic examination, severe perivascular edema and neutrophil infiltration were evident in lung tissues. These results suggest that increased vascular permeability and neutrophil sequestration in the lungs are important factors in lethal activity by cytolysin.

Effect of plumule and radicle on somatic embryogenesis in the cultures of ginseng zygotic embryos

Abstract: Immature zygotic embryos of ginseng produced somatic embryos on MS medium without growth regulators. However, in the culture of mature zygotic embryos, excision of the embryo was required for somatic embryo induction. Somatic embryos formed only on excised cotyledons without an embryo axis or on excised embryos without the plumule and radicle of the axis. This observation suggests that the axis tip of the embryo might suppress somatic embryo production although the cotyledon tissues have predetermined embryogenic competency. To clarify the role of the embryo axis on somatic embryo formation, excised plumules or radicles were placed in direct contact with the basal cut-ends of cotyledons. The adhesion of plumules or radicles highly suppressed somatic embryo formation from cotyledon explants. When an agar block containing exudate from excised plumules or radicles was placed in contact with the cut end of the cotyledon, a similar inhibition was observed. These results suggest that embryogenic competence is suppressed by endogenous inhibitors present in the axis tip of the zygotic embryo.

Insulin-like growth factor-I (IGF-I) and IGF-binding proteins in children with nephrotic syndrome.

Abstract: Growth failure appears to be a major problem for nephrotic children who fail to respond to steroid therapy. Recently altered serum insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) profiles are reported in renal failure and glomerulonephritis. In this study, the serum IGFBP profile was evaluated by Western ligand blot and RIA in 22 patients with the nephrotic syndrome. Serum IGFBP-3 was decreased, whereas IGFBP-2 was increased in most patients with the nephrotic syndrome. The mean serum IGFBP-3 level was 2123 +/- 531 ng/mL in active states and was increased to a normal level (3593 +/- 407 ng/mL) in remission states. We also measured serum IGF-I by RIA. The serum concentration of IGF-I (mean +/- SD) was 67.4 +/- 23.2 ng/mL in active states and was increased to 127.1 +/- 21.8 ng/mL in remission states, but was still lower than that in control subjects (180.4 +/- 15.8 ng/mL). IGF-I and IGFBP-3 levels were not correlated with primary renal diseases or the amount of proteinuria. For serum IGF-IGFBP complexes, 150-kDa complexes were significantly decreased in patients with the nephrotic syndrome compared with those in control subjects. In urine from nephrotic syndrome patients, 150- and 50-kDa complexes were found, whereas these complexes did not exist in the urine of control subjects. We speculate that low serum IGF-I and IGFBP-3 levels would be partially due to the increased urinary losses of serum IGF-IGFBP complexes, especially that of 150 kDa, and these changes may contribute to growth failure in persistent nephrotic syndrome.

An LQG based PSS design for controlling the SSR in power systems with series-compensated lines

Abstract: This paper presents a linear quadratic Gaussian (LQG) based-power system stabilizer (PSS) to control the subsynchronous resonance (SSR) that may occur in a series capacitor compensated power system This paper investigates the dominant parameters on the SSR using the critical compensation level (CCL), and selects the design parameters to confirm the stability robustness The complete SSR simulation system based on the IEEE first benchmark is employed in this study Eigenvalue analysis and time domain simulations using a nonlinear system model show that the proposed PSS can control the SSR efficiently

Phylogenetic analysis ofUlmaceae

Abstract: A phylogenetic analysis of theUlmaceae, Cannabaceae, Barbeyaceae, andBroussonetia of theMoraceae produced nine equally parsimonious trees with 127 steps TheUlmoideae (Ulmaceae, sensuGrudzinskaya) are a monophyletic group and distinct from theCeltidoideae The genusAmpelocera occupies an isolated taxonomic position among the celtidoids The similarity ofAmpelocera to the fossil celtidoid flowerEoceltis of North America suggests thatAmpelocera posesses an archaic suite of characters, and occupies a primitive position among the celtidoids, theCannabaceae and theMoraceae The relationships among the other celtidoid taxa,Cannabaceae, andBroussonetia are problematic TheCannabaceae andBroussonetia of theMoraceae are nested within the celtidoids suggesting that this is a paraphyletic group The close, but unresolved, relationship of the celtidoids to theMoraceae andCannabaceae observed in this analysis, and the appearance of the celtidoids in the fossil record prior to the ulmoids suggests that the evolutionary relationship of the ulmoids and celtidoids may be more distant than current taxonomic treatments reflect

Regulation of nad+ glycohydrolase activity by nad+-dependent auto-adp-ribosylation

Abstract: NAD+ glycohydrolase (NADase; EC 3.2.2.5) is an enzyme that catalyses hydrolysis of NAD+ to produce ADP-ribose and nicotinamide. Its physiological role and the regulation of its enzymic activity have not been fully elucidated. In the present study, the mechanism of self-inactivation of NADase by its substrate, NAD+, was investigated by using intact rabbit erythrocytes and purified NADase. Our results suggest that inactivation of NADase was due an auto-ADP-ribosylation reaction. ADP-ribosylated NADase of rabbit erythrocytes was deADP-ribosylated when incubated without NAD+, and thus enzyme activity was simultaneously restored. These findings suggest that reversible auto-ADP-ribosylation of NADase might regulate the enzyme's activity in vivo.

Muon-catalyzed fusion in deuterium at 3 K

Abstract: Muon-catalyzed fusion in deuterium has traditionally been studied in gaseous and liquid targets. The TRIUMF solid hydrogen layer target system has been used to study the fusion reaction rates in the solid phase at a target temperature of 3 K. Both branches of the cycle were observed; neutrons by a liquid organic scintillator, and protons by a silicon detector located inside the target system. The effective molecular formation rate from the upper hyperfine state and the spin exchange rate have been measured, and information on the branching ratio parameters has been extracted.

Somatic embryogenesis and plant regeneration in cotyledonary explant cultures of Chinese cabbage

Abstract: Cotyledonary explants of Chinese cabbage were cultured on Murashige and Skoog's medium supplemented with various concentrations of 2,4-dichlorophenoxyacetic acid Up to 20% of the cotyledonary explants produced somatic embryos with or without intervening callus production Explants became more competent as the age of the source seedlings increased up to 8 days, but cotyledonary explants from 10-day-old seedlings were not responsive Upon transfer to MS basal medium most of the somatic embryos developed into plantlets Plantlets were transplanted to potting soil and grown to maturity in a phytotron Among three cultivars used, only cotyledonary explants of ‘Top Salad’ were capable of producing somatic embryos

Intracellular ADP-ribose inhibits ATP-sensitive K+ channels in rat ventricular myocytes.

Abstract: Cyclic ADP-ribose (cADPR), an NAD metabolite, has been shown to be a messenger for Ca2+ mobilization from intracellular Ca2+ stores. However, the physiological role of ADP-ribose (ADPR), another metabolite of NAD, is not known. We examined the effects of cADPR and ADPR on the ATP-sensitive K+ channel (KATP) activity in rat ventricular myocytes by use of the inside-out patch-clamp configuration. ADPR, but not cADPR, inhibited the channel activity at micromolar range with an inhibitor constant (Ki) of 38.4 microM. The Hill coefficient was 0.9. ATP inhibited the K+ channel with a Ki of 77.8 microM, and the Hill coefficient was 1.8. Single-channel conductance was not affected by ADPR. These findings strongly suggest that ADPR may act as a regulator of KATP channel activity.

Properties and Capsid Protein Gene Sequence of a Korean Isolate of Barley Mild Mosaic Virus

Abstract: An isolate of barley mild mosaic virus (BaMMV-Kor) obtained from Iri, Korea-was characterized and compared with three BaMMV strains, BaMMV-Nal and BaMMV-Kal from Japan and BaMMV-M from Germany. Mechanical inoculation experiments showed that BaMMV-Kor was similar to BaMMV-Nal, but differed from BaMMV-Kal and BaMMV-M, in its pathogenicity towards Japanese barley cultivars. However, BaMMV-Kor differed from BaMMV-Nal, as well as from BaMMV-Kal and BaMMV-M, in that it infected most of the Korean naked barley cultivars tested. BaMMV-Kor was distinguished from three other BaMMV strains by ELISA. The sequence of the 3'-terminal 2500 nucleotides [excluding the poly (A) tail] of RNA 1 of BaMMV-Kor was determined to start within a long open reading frame coding for a part of the NIb polymerase (468 amino acids) and the entire capsid protein (251 amino acids), which is followed by a non-coding region (NCR) of 342 nucleotides. The capsid protein of BaMMV-Kor shows higher amino acid sequence homology with BaMMV-Nal (97.2%) than with BaMMV-Kal (92.0%). Likewise, in the 3' NCRs, BaMMV-Kor shows higher nucleotide sequence homology with BaMMV-Nal (96.5%) than with BaMMV-Kal (92.1%). These results indicate that BaMMV-Kor is a new strain of BaMMV, which is closely related to BaMMV-Nal, but differs both biologically and serologically from the Japanese and German strains.

Survival of Cryptosporidium muris (strain MCR) oocysts under cryopreservation.

Abstract: We have successfully maintained Cryptosporidium muris by cryopreservation. Oocysts were suspended in distilled water, stored at -20 degrees C for 24 hrs, and then cryopreserved at -70 degrees C. Cryopreserved specimens were slowly thawed at 5 degrees C. Oocysts, which had been cryopreserved for 15 months without cryoprotective agents, retained their infectivity by the mouse titration method. Oocysts stored at 5 degrees C in 2.5% potassium dichromate failed to retain their infectivity beyond 6.5 months.

Time-of-flight measurement of resonant molecular formation in muon-catalyzed dt fusion

Abstract: Preliminary results are reported for an experiment at TRIUMF where a time-of-flight technique was tested for measuring the energy dependence of the rate for muon-catalyzed dt fusion. Muonic tritium atoms were created following transfer of negative muons from muonic protium in a layer of solid hydrogen (protium) containing a small fraction of tritium. The atoms escaped from the solid layer via the Ramsauer-Townsend mechanism, traversed a drift region of 18 mm, and then struck an adjacent layer of deuterium, where the muonic atom could form a molecular system. The time of detection of a fusion product (neutron or alpha) following muon arrival is dependent upon the energy of the muonic tritium atom as it traverses the drift region. By comparison of the time distribution of fusion events with a prediction based on the theoretical energy dependence of the rate, the strength of resonant formation can in principle be determined. The results extracted so far are discussed and the limitations of the method are examined.

Temperature-dependent scanning tunneling spectroscopy of 1T-TaS2.

Abstract: We have studied temperature-dependent tunneling spectroscopy of 1T-${\mathrm{TaS}}_{2}$ from room temperature down to about 40 K. The spectra indicated an abrupt transition from the charge-density-wave-induced broad depletion to an opening of a deep pseudogap within 1 K of the nearly commensurate to commensurate transition temperature. The measured pseudogap was deep enough to form localized states at the Fermi level. In contrast to an inverse photoelectron spectroscopy study, our tunneling results indicate gap structures of two Hubbard subbands resulting from the band splitting of the Ta 5d band due to the electron correlation effect. We have also found an abrupt increase of thermoelectric voltage developing between the tip and sample at the transition temperature. \textcopyright{} 1996 The American Physical Society.

Preparation and characterization of TiO2 thin films by PECVD on Si substrate

Abstract: Titanium oxide thin films were prepared on p-Si(l00) substrate by plasma enhanced chemical vapor deposition using high purity titanium isopropoxide and oxygen. The deposition rate was little affected by oxygen flow rate, but significantly affected by RF power, substrate temperature, carrier gas flow rate, and chamber pressure. Morphology of the film became coarser with increasing deposition time and chamber pressure, and the film showed less uniformity at high deposition rates. It was also found that the overall deposition process is controlled by heterogeneous surface reaction below 200°C., but controlled by mass transfer of reactants at higher temperatures. TiO2 films deposited at temperatures lower than 400°C was amorphous, but showed the anatase crystalline structure upon 400°C deposition. The dielectric constant was about 47 for the films post-treated by rapid-thermal annealing (RTA) at 800°C. The leakage current was about 2×10−5 A/cm2 for the films deposited at 400°C and RTA-treated at 600°C. However, it was decreased to less than 3×10−7 A/cm2 for the film RTA-treated at 800°C.

UNIK-OPT/NN: neural network based adaptive optimal controller on optimization models

Abstract: When the future information for an optimization model is not complete, the model tends to incorporate such uncertainties as some assumptions on the coefficients. As time passes and more precise information is accumulated, the initial optimal solution may no longer be optimal, or even feasible. At this point, model builders want to modify the assumed and controllable coefficients to obtain the desired values of designated decision variables. To aid this process, a neural network could effectively be applied. So we develop a tool UNIK-OPT/NN which can support the construction and recall of the neural network model on top of the knowledge assisted optimization model formulator UNIK-OPT and the semantic neural network building aid UNIK-NEURO. By adopting a commonly interpretable semantic representation of optimization and neural network models, UNIK-OPT/NN can effectively automate most of the neural network construction and recall procedure for optimal control.

Adaptive sliding mode control based on FLS

Abstract: Fuzzy logic system (FLS) can be utilized to approximate a nonlinear function. In this paper, an adaptive sliding mode control (SMC) scheme in which FLS is used to approximate the unknown system function f in designing the SMC for nonlinear system is proposed. In order to reduce the approximation errors between the true nonlinear function and fuzzy approximator, a robust adaptive law is also proposed. The stability of the proposed control schemes are proved and the continuous control laws are designed by introducing the boundary layer concepts. These proposed control schemes are applied to an inverted pendulum system and comparisons between the two control schemes are shown in simulations.

Quantitative analysis of gene expression in sexual structures of Aspergillus nidulans by sequencing of 3′-directed cDNA clones

Abstract: We constructed a 3′-directed cDNA library of cleistothecia and Hulle cells of Aspergillus nidulans to examine gene expression patterns of the sexual structures and to have probes necessary to isolate sexual structure-specific genes. Sequencing of 360 randomly selected cDNA clones yielded 272 expressed sequence tags (ESTs), most of which probably represent frequently or less expressed genes in sexual structures of A. nidulans. Among the 272 ESTs, 33 ESTs (87 cDNA clones) appeared more than once and 2 ESTs appeared 6 times; 9 ESTs matched GenBank entries. When compared with sequences obtained from a mycelial 3′-directed cDNA library of A. nidulans, 28 out of 33 ESTs seem to be sexual structure-specific. Northern blot analyses of 20 ESTs showed that 17 are sexual structure-specific. The remaining three ESTs also hybridized with RNA isolated from vegetative mycelia. These results suggest that analyses of ESTs from different cell types or tissues can readily demonstrate gene expression patterns of specific cell types and identify cell type-specific cDNA probes.