Showing papers by "Korea University published in 1989"

Liposarcoma Arising in a Giant Lipomatous Polyp of the Esophagus

Abstract: A case of liposarcoma in a giant pedunculated lipoma of the esophagus in a 49-year-old Korean woman who presented intermittent swallowing difficulty for 3 years is reported. Endoscopy and esophagography revealed that a giant smooth longitudinal tumor mass almost entirely occupied the esophageal lumen. A total esohagectomy was done. The tumor was 20 cm in length and 7 cm in average diameter with an obvious stalk measuring 3 cm in length and 1 cm in diameter. Microscopic examination disclosed a lipoma with focal ulceration and liposarcomatous change infiltrating into interstitial fibrous tissue at its distal end.

Storage proteins of the fall webworm, Hyphantria cunea Drury

Abstract: Two storage proteins, storage protein-1 (SP1) and storage protein-2 (SP2), were found in hemolymph and fat body during the development of Hyphantria cunea, the fall webworm. Both storage proteins show similiar quantitative changes during development in males and females; however, SP1 is more abundant. The hemolymph of last instar larvae contains high concentrations of the storage proteins. However, following pupation, the storage proteins accumulate in fat bodies. SP1 peaks in the hemolymph of males and females late in last instar larvae (8-day-old 7th instar larvae). SP1 has a native molecular weight of 460,000 and consists of six identical subunits (Mr = 76,700), while SP2 has a molecular weight of 450,000 and is composed of two different subunits (Mr = 74,100 and 72,400). Both SP1 and SP2 are hexamers and are phosphorylated glycolipoproteins. The pl values of SP1 and SP2 were determined to be 5.70 and 5.50, respectively. Antibodies raised against SP1 react positively with vitellogenin and ovary extract, as well as with proteins in the hemolymph from last instar larvae and proteins in pupal fat bodies. Storage protein synthesis starts in fat bodies of a 4-day-old 7th instar larvae and in female peaks at 6–8 days of the 7th instar.

Hantavirus infections in humans and commensal rodents in Singapore

Abstract: To determine the extent of hantavirus infection in Singapore, serological studies using the indirect immunofluorescent antibody (IFA) test were conducted on commensal rodents and on human patients in 4 diagnostic groups. Virus isolation using a Vero E6 cell line was performed on hantaviral antigen-positive rodent lung tissue. Of 142 rodents and 3 insectivores studied, 37 (26%) were seropositive for IFA. Rattus norvegicus was the predominant species captured, with the highest species-specific seropositive rate of 32% (36 of 113). A hantavirus strain, R36, was isolated from one R. norvegicus. Seropositive rates for human patients were: 8% respectively for dengue haemorrhagic fever suspects and for non-A non-B hepatitis patients, 3% for leptospirosis suspects and 2% for acute nephritis patients. 2 patients had marked liver dysfunction but mild renal involvement. This hepatitis-like manifestation appears to be a clinical variant of hantavirus infection.

Sapogenins from Melandrium firmum

Abstract: Two sapogenins isolated from MELANDRIUM FIRMUM are shown to have the structures of 3beta,21beta-dihydroxy-16,23,dioxo-28-nor-17alpha,18beta-olean-12-ene and 3beta-16alpha-dihydroxy-23-oxo-olean-13(18)-en-28-oic acid, respectively by spectral data and X-ray crystallographic analysis.

Ultrastructure at the host-parasite interface of Phytophthora capsici in roots and stems of Capsicum annuum

Abstract: The infecting hyphae of Phytophthora capsici grew intercellularly in infected tissues of roots and stems of pepper (Capsicum annuum). The vascular tissues were not markedly disorganized even when heavily infected. Intercellularly growing hyphae penetrated the host cells by forming haustorium-like bodies. The consistent features of ultrastructural changes in infected tissues of pepper roots and stems were degeneration of cell organelles and dissolution of host cell walls. The cytoplasm detached from the cell wall aggregated abundantly around some haustorium-like bodies or the penetration sites of fungal hyphae. The host cell walls were palely stained, thinned and swollen, possibly being biochemically altered by the action of fungal macerating enzymes. Electron-dense, wall-like material was apposed on the outer wall of xylem vessel contacted by fungal hyphae. The infecting hyphae were also surrounded by granular, dark-staining cytoplasm. Characteristics of host cell responses to the invading P. capsici were the deposition of papilla-like material on host cell walls next to hyphae and the encasement of haustorium-like bodies with wall appositions.

Carbohydrate Composition and Acid Invertase Activity in Rice Leaves Infected with Pyricularia oryzae

Abstract: Ethanol-soluble carbohydrates in healthy and blast-infected leaves and also cultures of Pyricularia oryzae were analyzed using gas chromatography Arabitol, mannitol, and trehalose occurred in infected leaf tissue, but not in healthy controls Cultures of P oryzae contained mannitol and trehalose, but not arabitol and sucrose The presence of arabitol only in blast-infected rice leaves suggests that arabitol synthesis may be induced in infected leaf tissue as a result of the rice-blast fungus interaction, but may not be within blast fungus itself The amounts of glucose, fructose, and sucrose in infected leaves were slightly increased until 5 days, and greatly enhanced at 7 days after inoculation, There were no differences in amounts of these sugars between the cultivars Nakdong and Dobong At 7 days after inoculation, increases in amounts of arabitol, mannitol, and trehalose were pronounced in the susceptible cultivar Nakdong than in the moderately susceptible cultivar Dobong The increased amounts of glucose and fructose in infected plants of the two cultivars were closely correlated with the presence of a very active invertase Zusammenfassung Athanollosliche Kohlenhydrate in gesunden und mit Reisbraune infizierten Blattern und auch in Pyricularia oryzae-Kulturen wurden gaschromatographisch analysiert Arabitol, Mannitol und Trehalose waren im infizierten Blattgewebe vorhanden, aber nicht im gesunden Cewebe P oryzae-Kulturen enthielten Mannitol und Trehalose, aber kein Arabitol und Saccharose Das Vorhandensein von Arabitol nur in durch Reisbraune infizierten Blattern ist ein Hinweis dafur, das die Arabitolsynthese im infizierten Blattgewebe durch die Wechselwirkung zwischen Reis und P oryzae induziert sein kann, aber nicht innerhalb von P oryzae selbst Die Gehalte der Glukose, Fruktose und Saccharose in den infizierten Blattern waren bis funf Tage nach der Infektion etwas, aber am siebten Tage stark erhoht Die Niveaus dieses Zuckers waren zwischen den Sorten Nakdong und Dobong nicht unterschiedlich Am siebten Tage nach der Infektion waren die Zunahme von Arabitol, Mannitol und Trehalose in der anfalligen Sorte Nakdong mehr ausgepragt als in der mittelmasig anfalligen Sorte Dobong Die zunehmenden Gehalte von Glukose und Fruktose in den infizierten Pflanzen der zwei Sorten korrelierten stark mit den Invertaseaktivitatniveaus

A clinical study of hemorrhagic fever with renal syndrome caused by Seoul virus infection.

Abstract: The clinical findings of 29 patients with hemorrhagic fever with renal syndrome (HFRS) caused by Seoul virus were evaluated and compared with the previously reported clinical findings of classic Korean hemorrhagic fever (KHF). The diagnoses of these patients were made by hemagglutination inhibition test. The results were as follows: The disease occurred predominantly in males with a high incidence in the third and fourth decades of life. The highest incidence of the disease occurred in October–December. Major symptoms were fever, abdominal or flank pain, vomiting and myalgia. Major signs were petechia, CVA tenderness, pharynegeal injection, and conjunctival infection, but these signs were much less common than in patients with classic KHF. The treatments were mainly conservative and there was no fatal case in the study subjects. These findings suggest that the clinical course of Seoul virus infection may be much milder than that of classic KHF and the outcome may be more favorable.

Demonstration of species-specific and cross reactive components of Paragonimus westermani crude worm antigen by EITB.

Abstract: Enzyme-linked immunoelectrotransfer blot (EITB) using crude worm antigen of adult Paragonimus westermani was performed for human patients sera to identify the species-specific components. Crude antigen was obtained by homogenizing and centrifuging 24-week old adult worms at 10,000 rpm for 60 minutes in phosphate buffered saline (PBS, PH 7.2) containing: Phenyl methyl sulfonyl auoride (PMSF). Gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) was performed and blotted electrophoretically onto a sheet of nitrocellulose paper. The sheet was cut into strips and exposed to sera diluted 1 : 200 with PBS. SDS-PAGE showed 26 protein bands ranging 229 to 10 kDa. Of them 229, 91, 60, 50, 35∼31, 27, 25, 21, 17, 11 and 10 kDa components showed positive reaction with serum antibody of patients with p. westermani. Sera of patients infected with Clcnorchis sinensis reacted with 35∼31, 19, and 11 kDa bands. Human sera from cysticercosis and diphyllobothriasis cases showed non-specific cross reactions with 229, 35∼31, 27, 25 and 17kDa bands. Protein bands of 91, 60, 21 and 10kDa showed strong positive reaction without cross reactions with sera from other helminthic infections. Key words: Paragonimus westermani. western blot/EITB, immunodiagnosis, human paragonimiasis

Studies of bipolarity in fluidized bed electrodes

Abstract: Measurements have been made of the anodic reaction products due to the anodic over-potential resulting from the bipolarity of particles in a nominally cathodic fluidized bed electrode reactor. Investigations of the lead particle-basic carbonate solution system show that charge transfer occurs by a bipolar as well as a monopolar mechanism in a nominally monopolar fluidized bed electrode. The bipolar intensity was found to increase with decreasing superficial current density and also with increasing bed voidage.

Synthesis and properties of polyesters of isomeric poly(oxynaphthyleneoxy‐2‐bromoterephthaloyl)s

Abstract: A series of aromatic polyesters were prepared from 2-bromoterephthalic acid and naphthalenediol isomers. Only the polymers obtained from 1,4-, and 1,5- and 2,6-naphthalenediols were thermotropic nematogens and those from bent naphthalenediols were not liquid crystalline. Only the polyesters derived from 1,4-, 1,5-, and 2,6-naphthalenediols were semicrystalline. The melting temperatures ranged from 319 to 374°C depending on the structure of naphthalenediol moiety. The glass transition temperature, Tg, ranged from 95 to 168°C. TGA studied revealed that the polyesters have fairly good thermal stability

Effect of Temperature on the Elongation Rate and the Estimation of Weight of Asparagus Spears

Abstract: 1. The effect of temperature on the elongation rate of spears from 1-year-old asparagus was studied under dark conditions.Crowns were dug from the field and planted in pots, which were placed in temperature-controlled chambers. Sprouting of spears was influenced by temperature. It took 11-13 days at 10 and 15°C, and about 4 days at 20 to 40°C from the start of treatments, for sprouting to occur.Elongation rates of spears increased with increasing temperatures between 10 and 30°C, and then decreased at 35°C. Spears sprouted but stopped growing very soon at 40°C. The relative growth rate (RGR) of spears decreased curvilinearly with time. The logarithm of RGR decreased linearly with time. This result shows that spears grow doubly exponentially and that growth can be fitted by Gompertz equation (Length=A• exp(-B•exp(-Ct)), t=time).The values of the parameters A and B increased linearly with temperature between 10 and 20°C. but not changed between 20 and 30°C. The value of parameter C was increased linearly with temperature between 10 and 30°C. In an Arrhenius plot of parameter C, a linear relation was found between 10 and 30°C, with a discontinuity between 30 and 35°C.2. Fresh and dry weight of spears were estimated non-destructively by use of circumference at the base (C) and height (L) for white spears from 1-year-old crowns and green spears from 9-year-old ones.Fresh weight correlated very well with C2L for spears. The correlation coefficient was 0.975 for white spears and 0.983 for green spears. Dry weight also correlated very well with C2L but the correlation coefficients were lower than for fresh weight; they were 0.945 for white spears and 0.968 for green spears.

Synthesis and electrical conductivity of poly(1,4-phenylenevinylene-co-2,5-thienylenevinylene)†

Abstract: Copolymers containing either 1,4-phenylenevinylene or 2,5-dimethoxy-1,4-phenylenevinylene units combined with 2,5-thienylenevinylene units were prepared in film form from precursor polymer films of the respective sulfonium salt polymers, which, in turn, were synthesized by the copolymerization of the respective bis(sulfonium salt) monomers. All of the copolymers could be “doped” with iodine to obtain films with high electrical conductivities and good air stability.

Liquid Crystalline Properties of the Copolyesters Prepared from Resorcinol, p -Hydroxybenzoic Acid, and Terephthalic Acid

Abstract: A series of aromatic copolyesters was prepared in melts from 1,3-diacetoxybenzene, terephthalic acid and p-acetoxybenzoic acid, and the copolyesters’ liquid crystalline and other properties were investigated. The compositions containing more than 65 mol% the p-oxybenzoyl (POB) unit exhibited thermotropic behavior, whereas those with less than 40 mol% the POB structure were not thermotropic. The copolyesters with an intermediate level (50–60 mol%) of POB units showed an interesting, shear flow induced formation of mesophases. The possibility of compositional heterogeneity in the copolyesters was demonstrated by collecting and characterizing insoluble fractions.

Isothermal capacitance transient spectroscopy (ICTS) study for midgap levels in Hb-GaAs by rapid thermal annealing

Abstract: We studied the midgap levels by using isothermal capacitance transient spectroscopy (ICTS) in Hb-GaAs which had been processed by rapid thermal annealing (RTA). As the annealing time at 850 °C increased, the EL2 trap (E c−0.81 eV) was transformed to the EX2 trap (E c−0.73 eV) and eventually to the EX1 trap (E c−0.87 eV). The diffusivity of the EL2 trap obtained from the experimental result of the heat treatment was about 1.02·10−8cm2/s at 850 °C. This result indicate that the EL2 trap contains an interstitial arsenic atom. The result of the transformation to the EX1 and EX2 traps suggests that, when the EL2 trap is VAsASiVGaAsGa, the EX2 trap may be VAsVGaAsGa, which Asi is diffused out during a thermal annealing.

Effects of Quantity and Temperature of Storage Roots on the Elongation Rates of Asparagus Spears

Abstract: Effects of quantity and temperature of storage roots on the elongation rates of spears were studied using 1-year-old asparagus.1. The elongation rates were affected by the sizes of crowns. The spears from normal-sized crowns grew exponentially, but those from small-sized crowns grew almost linearly.2. The spears grew exponentially while storage materials were plentiful in storage roots, but grew linearly and then parabolically as the materials were exhausted.3. The elongation rates of spears were influenced by root temperature. Rates were highest at 20 or 25°C. The more the temperature deviated from these levels, the more the rates decreased. But spears grew exponentially even at aroot temperature of 5°C. It was probable that root temperature affected the elongation growth of spears not directly, but indirectly by modifying the temperature of spear and/or rhizome.4. The temperature treatments of buds for about 2.5 days before sprouting did not influence the subsequent elongation growth of spears.5. The ratios of water-weight: dry-weight in spears grown at root temperature of 10°C were lower than those at 15 or 20°C.It was suggested that as long as available storage materials were plentiful, spear growth was mostly influenced by spear and/or rhizome activities rather than by root activity.

Quantum mechanics of a molecular system adsorbed on a dielectric surface

Abstract: : A molecular system adsorbed on a dielectric surface is modeled as a damped harmonic oscillator driven by a sinusoidal external force. The exact propagator and wavefunction through the Feynman path integral method are obtained. The second quantities are evaluated. The amplitude for transitions between harmonic oscillator states and damped driven oscillator states are obtained explicitly, and the result is applied to a two-level system. Keywords: Dielectric surface; Adsorbed molecular system; Quantum mechanics; Damped harmonic oscillator; Sinusoidal external force; Feynman path integral.

Electrical-conductivity of polyblends of poly(1,4-phenylene vinylene) and poly(2,5-dimethoxy-1,4-phenylene vinylene)

Abstract: A series of polyblends of poly(1,4-phenylene vinylene), PPV, and poly(2,5-dimethoxy-1,4-phenylene vinylene), PDMPV, were prepared in film form from precursor polyblends of the respective sulfonium salt polymers, which were separately prepared from the respectivebis(sulfonium salt) monomers. The blend films were doped with I2 at room temperature to obtain a wide range of electrical conductivities (10−2 to 102Scm−1) depending on the blend composition. The higher the content of PDMPV in the blends the higher was the conductivity.

In vitro differential developmental toxicity of vitamin A congeners.

Abstract: Several forms of vitamin A were tested in the in vitro hydra assay for their developmental toxicity hazard potential and site of action on progressive ontogenesis. Retinol, retinyl acetate, retinaldehyde, all trans retinoic acid, and 13 cis retinoic acid were tested fully, and each was established clearly as being able to perturb development of artificial hydra "embryos" at, or near, adult toxic treatment levels. All forms of vitamin A tested interfered with differentiation, but, although the alcohol, acetate, and aldehyde forms (group I) prevented the initial stages of differentiation from occurring, the acid forms (group II) allowed the initial stages of differentiation to occur but not the final differentiation of tentacle buds. Group I compounds produced the developmental toxicity endpoint after as little as 24 h of transient exposure on the first day of development, but had no permanent effect on development at their minimal affective developmental concentration (D-MAC) when exposure began after the first day of development. In contrast, transient 24-h exposure to group II forms did not interfere with development. At, or even above, a concentration greater than the D-MAC, more continuous exposure to them was required to interfere with differentiation. Consistent with tests of other chemicals, the concentrations needed to produce effects in hydra bore no relation to those needed to produce effects in mammals.

Structure of PPTA fibers derived directly from a liquid crystalline prepolymer dope in an organic solvent

Abstract: The structure and properties of the pulp-like aromatic polyamide PPTA fibers prepared directly from a polymerization medium were studied by scanning electron microscopy (SEM), X-ray diffractometry, and polarizing light microscopy. The morphology of the fiber appears significantly different from that of Kevlar and does not reveal a skin-core structure. Regular defect bands and, thus, the regular clustering of the chain ends also could not be observed.