Showing papers by "Chonbuk National University published in 1993"

An "in-out" strategy using gene targeting and FLP recombinase for the functional dissection of complex DNA regulatory elements: analysis of the beta-globin locus control region

Abstract: The human beta-globin locus control region (LCR) is a complex DNA regulatory element that controls the expression of the cis-linked beta-like globin genes located in the 55 kilobases 3' of the LCR. We have initiated the functional analysis of the LCR by homologous recombination in murine erythroleukemia cell somatic hybrids that carry a single copy of human chromosome 11 on which the beta-globin locus is situated. High-level expression of the human beta-globin gene normally occurs when these hybrid cells are induced to differentiate. We have reported that the insertion of an expressed selectable marker gene (driven by the Friend virus enhancer/promoter) into the LCR disrupts the LCR-mediated regulation of globin transcription. In these cells, beta-globin is no longer expressed when the cells differentiate; instead, expression of the selectable marker gene increases significantly after differentiation. Since present techniques for homologous recombination require the insertion of a selectable marker, further progress in using homologous recombination to analyze the LCR depends on deletion of the selectable marker and demonstration that the locus functions normally after the insertion, expression, and deletion of the selectable marker. Here we show that after precise deletion of the selectable marker by using the FLP recombinase/FRT (FLP recombinase target) system, the locus functions as it did before the homologous recombination event. These studies demonstrate the feasibility of using homologous recombination to analyze the LCR in particular, and other complex cis-regulatory DNA elements in general, in their normal chromosomal context.

Complete obstruction of the nasolacrimal system. Part I. Treatment with balloon dilation.

Abstract: Fluoroscopically guided balloon dilation in treatment of complete obstruction of the nasolacrimal system was assessed in 39 eyes of 35 patients. All patients had severe epiphora. With nasal endoscopic guidance, a 0.018-inch guide wire was introduced through the superior punctum into the inferior meatus of the nasal cavity and was pulled out through the nasal aperture with a hemostat. A deflated angioplasty balloon catheter was passed retrograde over the guide wire through the inferior meatus until it straddled the stricture. Balloons were dilated with water-soluble contrast medium. No major complications occurred. At 7 days after balloon dilation, epiphora decreased in 22 of 39 eyes; 17 demonstrated complete resolution of severe epiphora, and five showed incomplete resolution. At 2 months, improvement had not been maintained in 10 of the 22 eyes. This technique for treatment of complete obstruction of the nasolacrimal system is simple and safe, but the high failure and recurrence rates in this study are n...

A simple concealment for ATM bursty cell loss

Abstract: In the ATM (asynchronous transfer mode) network, a fixed-length packet (cell) which contains a header and an information field is used to provide integrated services, but bit error and cell loss error are inevitable. In order to cope with cell loss, pixel arrangement (PR) and block rearrangement (BR) are presented. The PR and BR are used for the concealment of ATM cell loss. This scheme is able to reduce the blocking effects and restore the sequential burst cell loss errors. Computer simulation shows that the concealment of even the burst cell loss improves the image quality. >

Obstructing cancer of the gastric antrum: palliative treatment with covered metallic stents.

Abstract: A new technique, which requires a simple surgical gastrostomy without general anesthesia, is described for placement of covered expandable metallic stents. This technique was performed successfully in a patient with malignant obstruction of the gastric antrum, obviating palliative surgical resection.

Complete obstruction of the nasolacrimal system. Part II. Treatment with expandable metallic stents.

Abstract: To evaluate the clinical usefulness of expandable metallic stents for maintenance of the dilated nasolacrimal sac and duct, double stents were implanted under fluoroscopic guidance in seven patients with severe epiphora after failed balloon dacryocystoplasty. Stents were constructed of 0.25-mm stainless steel wire in a cylindrical zigzag configuration of 10 bends. A single stent was 4 mm in diameter when fully expanded and 10 mm long. The stent was placed accurately in all but one patient, in whom a second stent was placed accurately after removal of the dislodged stent with a hemostat under endoscopic guidance. After stent placement, all patients demonstrated complete resolution of epiphora. During follow-up of 4-20 weeks, complete blockage of the stent occurred in one patient. This was treated with intrastent balloon dacryocystoplasty. No stents migrated. Although the long-term validity of this treatment has not been proved, expandable metallic stents seem to be of value in the treatment of complete obstruction of the lacrimal sac and nasolacrimal duct.

Fully relaxed point defects in crystalline silicon.

Abstract: We have studied intrinsic point defects in crystalline silicon via a tight-binding molecular-dynamics scheme. The intrinsic defects studied in this work are the vacancy, the interstitial, the divacancy, the split divacancy, and the vacancy-interstitial complex. Fully relaxed geometries, gap states, and formation energies are investigated. It is shown that the relaxation effects cannot be neglected, in particular, in the peak position of band-gap states

Distribution of Gallium-67 in Normal and Hypotransferrinemic Tumor-Bearing Mice

Abstract: The mechanism by which 67Ga accumulates in tumors is controversial. The most popular theory is that 67Ga binds to transferrin and gains access to cells by the transferrin receptor. However, substantial evidence suggests that uptake of 67Ga may not be universally mediated by transferrin in tumors. To determine whether transferrin is required for uptake of 67Ga in vivo, we compared the uptake of 67Ga by two types of implanted tumors and by normal tissues in normal and severely hypotransferrinemic strains of Balb/C mice. One type of tumor was strongly gallium-avid in normal mice; the other was not. Uptake of 67Ga by normal soft tissues was markedly less in hypotransferrinemic than in normal mice. Uptake of 67Ga by bone was equivalent in the two types of mice. For the more gallium-avid tumor, uptake of 67Ga was similar and the ratio of tumor-to-background activity was substantially higher in the hypotransferrinemic than in the normal mice. For the less gallium-avid tumor, uptake was significantly less in hypotransferrinemic than in normal mice. These data suggest that uptake of 67Ga by bone and by some tumors may be a transferrin-independent process.

Comparison of the effects of the laryngeal mask airway and endotracheal intubation on vocal function

Abstract: We have compared changes in vocal function produced after insertion of a laryngeal mask airway (LMA) with those produced by tracheal intubation in 20 patients. Using acoustic waveform analysis, we computed amplitude variability (AV), pitch variability (PV), harmonics-to-noise ratio (HNR) and additive noise level (ANL) before anaesthesia and at 1, 4, and 24 h after tracheal extubation. There were no significant changes in vocal function after extubation except for HNR ratio (P = 0.046) at 4 h in the LMA group. There were differences in all four variables at 1 h, 4 h, or both, after tracheal extubation compared with baseline in the tracheal tube group. In both groups, all variables were the same as baseline values 24 h after extubation. We observed significant differences in AV (4 h), PV and ANL (1, 4 h) values between the two groups. These observations suggest that the LMA causes less vocal change than tracheal intubation (Br. J. Anaesth. 1993; 71: 648–650)

Adaptive control based on explicit model of robot manipulator

Abstract: Adaptive and nonadaptive control algorithms, which make use of a fundamental mathematical property concerning positive definite matrices and Lyapunov stability theory, are proposed for the control of robot manipulators. Using the fact that the matrix dD(q)/dt-2C(q, dq/dt) is skew symmetric, nonadaptive controllers which have a simplified structure with less computational burden are proposed. Using the dynamic equations for robot manipulators, parameter adaptation rules are developed for updating the controller's partially or totally unknown parameters, generalizing them to model reference adaptive controllers. To further take advantage of the simplified structure of the proposed adaptive controllers, a method for deriving the dynamic model of a robot manipulator which is linear in terms of its parameters is given. This dynamic model is also suitable for the pure identification of the parameters of links and payload of the manipulator. >

Efficacy of fumagillin against Thelohanellus kitauei infection of Israel carp, Cyprinus carpio nudus.

Abstract: The potential of fumagillin dicyclohexylamine salt to treat and prevent intestinal giant-cystic disease in Israel carp, Cyprinus carpio nudus, was monitored in field experimental studies. In experiment 1 (therapeutic), most fish were already naturally infected with more advanced stage of Relohqnellu: kitnuet. Fumagillin was administered to ash (mean body weiht of 830 g for a Penod of one month at a dose of 10.62 mg in the first group and 5.3 mg in the second group per fi sh per day. In experiment 2 (fprophylactlcl), most flesh also were already naturally infected with an early developmental stage of the protozoa and fish (average body weight of 484 g) were administered fumagillln for 45 days at a dose of 3.95 mg per fish per day. In both experiments, the cumulative mortalities of fish and the extrusion rates of the polar filaments of the spores were significantly decreased in a dose-independent fashion. In experiment 2 no dead fish were observed. No adverse side effects of the drug were observed among fish from any dosage group. In experiment 2, an oval or dot-like concave lesion of most cysts developed at the 7th day and the vegetative form was never observed at the 17th day postmedication and the cysts were grossly reduced in size as compared with the control group, beginning at the 24th day until the end of the study. In contrast, it was scarcely effective to the cysts in experiment 1. Taking the seasonal development of the protozoa into consideration, the above results revealed that oral administration of fumagillin at 3.95 mg/500 g body weight/day for a month Is the optimal dose for the treatment and prevention of thelohanellosls caused by T kitnuei among C. carpio nudus. Key words: Thelohanellus kitauei, Cypirinus carpio kudus, fumaglllin dicyclohexylamine salt, efficacy

Ordering of Missing-Row-Defects Forming (2×n)-Bi Phases on the Si(100) 2×1 Surface Studied by the Scanning Tunneling Microscopy

Abstract: (2×n)-Bi phases formed on the Si(100) 2×1 surface are studied by LEED and scanning tunneling microscopy. A series of well ordered (2×n) superlattices, with n ranging from 5 to 12, are observed. The STM images show that the (2×n) structures result from the formation of the periodic arrays of the missing Bi-dimer rows. The n of the (2×n) structure is found to depend on the Bi coverage θ with a relationship of θ=1-1/n. However, for the phases with n smaller than 5, the ordering of missing rows in the "n" direction is found to be disturbed by the competing formation of rectangular and linear type defects. The formation of successive (2×n) phases as a function of coverage suggests the presence of strong long range repulsive elastic interactions among missing Bi-dimer rows.

Diagnostic Value of Exclamation Mark Hairs

Abstract: Exclamation mark (EM) hair can lead to the misdiagnosis of alopecia areata (AA) because it is widely considered as pathognomonic for AA. Typical EM hairs were also found in trichotillomania. EM hairs

Adaptive nonlinear control of one-link flexible arm

Abstract: When a flexible arm is rotated by a motor about an axis through the arm's fixed end, transverse vibration may occur. The motor torque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible arm so that it is arrested at the end of rotation. In this paper, the authors propose deterministic and adaptive control laws for one-link flexible arm. Using the fact that matrix dD(/spl delta/)/dt-2C(/spl theta/, /spl theta//spl dot/, /spl delta/, /spl delta//spl dot/) is skew symmetric, controllers which have a simplified structure with less computational burden are proposed by using Lyapunov stability theory.

Scanning tunneling microscopy of √3×√3-Bi reconstruction on the Si(111) surface

Abstract: Bi-induced (√3×√3)R30° structures formed on the Si(111) surface are studied using scanning tunneling microscopy (STM) and LEED. Three distinct phases: monomer, trimer and honeycomb phases are identified for the first time by STM, depending on the Bi coverage, even though the √3×√3 symmetry has been always preserved in the LEED observation. At low coverages, Bi atoms are found to occupy the T4 site. In this adsorption geometry, a monomer phase (α-phase) are formed stably up to an ideal coverage of 1/3 ML. In trimer symmetry (β-phase) at saturation coverage of 1 ML, the individual atoms of the Bi clusters are clearly resolved. Between these two coverages, however, a honeycomb-type √3×√3 reconstruction has been also found, by STM, to co-exist with the trimer phase. This result reveals a new coverage dependent reconstruction process involving the √3×√3 reconstruction of Si(111) surface.

An expanded 2D DCT algorithm based on convolution

Abstract: Various convolutional approaches to computing the 1D and 2D discrete cosine transform (DCT) are presented. In the 1D case the method of W. Li (see IEEE Trans. Signal Process., vol.39, no.6, p.1305-13, 1991) is introduced, and a more regular structure than that of the Li method is described. Since both methods are complicated to implement with systolic arrays, a proper array structure is proposed. This structure speeds up the multiplication by processing with real numbers instead of complex numbers. The 2D algorithm and structure are obtained by expansion of the 1D algorithm. The resulting structure is faster than the 1D structure and requires fewer processing elements. >

Mechanistic Study of Silicon Etching in HF ‐ KBrO3 ‐ H 2 O Solution

Abstract: The chemical etching of silicon in mixed solution has been investigated experimentally. The etch rates were examined with varying and concentrations, agitation speed, and etching temperature. The etch rates were similar for both n‐ and p‐type Si(100). HF played an important role for accelerating the formation rate of holes at the silicon surface and the removal rate of formed on the wafer surface during the reaction. A comprehensive mechanism for the surface species formation and the silicon etching as a function of etchant concentration was developed. The holes formed at the silicon surface accelerated the etch rate and the formation of the layer. For high concentration, we suggest that the rate‐determining step of the reaction was the formation of holes at the silicon surface.

Leptospirosis Serology in Korean Wild Animals

Abstract: A study was undertaken on wild animals to determine the seroprevalence of animal leptospirosis in Korea. Using the serum microagglutination test for 19 serogroups, it was shown that two of 26 rats (Rattus rattus) had antibodies to Leptospira canicola. When data for domestic animals were included, the most prevalent (nearly 50%) serogroup was Leptospira canicola.

Studies on isosporosis in dogs. I: Isolation and sporulation of Isospora ohioensis.

Abstract: Based on the morphologic characteristics of oocysts of the genus Isospora, we have demonstrated that I. ohioensis is a relatively common Isospora species in dogs which are resident in Chonbuk province, Korea. The prepatent period of I. ohioensis was four days. The size of the unsporulated oocysts in fresh stool specimens was 22.9 x 19.8 microns (R = 1.16). The size of the contracted sporonts was 17.4 x 16.3 microns (R = 1.06). By 96 hours, sporulation is complete and the ratio of length/width was constant relatively. And the sizes of oocysts and sporocysts were 22.8 x 20.5 microns (R = 1.11) and 15.0 x 10.8 microns (R = 1.39), respectively. At this time it is most reliable for the measurements of oocyst sizes of I. ohioensis to provide with the identifiable clues against the others. It is therefore recommended that the clinical fecal specimens suspected of isosporosis should first be incubated and aerated for 96 hours before a definitive parasitological diagnosis can be reached. These and other observations contribute to the understanding of the biological characteristics and laboratory and clinical diagnosis of isosporosis.

Adhesive Property of Several Engineering Plastic Films Treated with Sputter Etching and Argon Low Temperature Plasma

Abstract: Engineering plastic films such as polyethylene terephthalate, nylon 6, polyimide, p-aramid, polycarbonate and Polyphenylene sulfide were treated with sputter etching and low temperature argon plasma, and their adhesive properties were investigated in relation to critical surface tension, SEM photograph and ESCA measurement. Peel strength increased by sputter etching and argon low temperature plasma treatments, especially with the former. Although critical surface tension increases by both treatments in one minute, adhesive property considerably increases by sputter etching over 3 min, because the treatment causes physical change such as surface roughness and protrusion. Thus, the sputter etching seems much more effective to increase the peel strength.

Thermal property and miscibility of polycarbonate/copolyester blends

Abstract: The thermal property and the miscibility of polycarbonate (PC)/copolyester blends were investigated. For the study, different copolyesters were synthesized from terephthalic acid (TPA) and various mixtures of ethylene glycol (EG) and cyclohexane dimethanol (CHDM). Various blends of PC and copolyester were prepared by melt mixing and thermal properties of the blends were studied employing differential scanning calorimeter. It was found that the blends of the PC and the copolyesters were partially miscible when the glycol in the copolyester was composed of 10, 20, or 30 mole % CHDM. However, the blends of the PC and the copolyesters were miscible in all proportions when the glycol in the copolyester was composed of 50 or 70 mole % CHDM. Miscibilities of the PC/copolyester blends depending on the composition of the copolyester are discussed based on the thermal properties of the blends.

Fiber Orientation of Polymer Injection Weld and Its Strength Evaluation

Abstract: This paper discusses the microstrure related fracture behavior of short-fiber reinforced thermoplastics. The microstructure of an injection molded weld was studied by microscopic methods for the purpose of describing fiber orientation. Injection welds are the place where two flow fronts come together, leading to fiber orientations having flower and volcano-like patterns. The polymer composite materials used in the experiment were polycarbonate(PC) with amorphous structure containing 30% short glass fiber and polyphenylene sulfide(PPS) with crystalline structure containing 40% short glass fiber. The specimen used was a dumbbell type tensile specimen with a weld line created by double gate injection molding. Microtoming technique was used for slicing ultrathin sections from the molded polymer parts. Microstructural analysis of fiber orientation at injection weld was carried out using light transmission microscopy (LM) and scanning electronic microscopy (SEM).

Human renal dipeptidase from kidneys of renal stone patients: Partial purification

Abstract: Human renal dipeptidase (RDPase) was purified from surgically removed kidneys of renal stone patients by affinity chromatography using its specific inhibitor, cilastatin, as the ligand. The partial purified RDPase of 6 mg exhibited specific activity of 99.4 unit/mg with 2,029 fold purification. It was composed of a slow moving major band (96%) and a fast moving minor band (4%). The minor band was not a contaminant as it showed a dipeptidase-specific activity. The kinetic parameters determined with glycyldehydrophenylalanine (Gdp) as synthetic substrate were Vmax, 322.6 μmol/min/mg and Km, 0.102 mM. This experiment provided biochemical evidences that surgically removed, nonfunctional kidneys in respect of glomerular filtration still retained high activity of renal dipeptidase.