Showing papers by "Kangwon National University published in 1999"
TL;DR: In this article, the effects of various naturally occurring flavonoids on NO production in LPS-activated RAW 264.7 cells were evaluated in vitro and the most active among 26 flavonoid derivatives tested were apigenin, wogonin, and luteolin.
508 citations
TL;DR: It is reported that NO suppresses proteolytic processing and activation of multiple pro-caspases in intact cells, including caspase-3 and caspas-8, and establishes the capacity of NO to inhibit not only active caspases but also caspasing activation.
263 citations
TL;DR: It is suggested that the ctl-1 catalase is needed during periods of starvation, as in the dauer larva, and that its misexpression in daf-c and clk-1 adults extends lifespan.
Abstract: The dauer larva is an alternative larval stage in Caenorhabditis elegans which allows animals to survive through periods of low food availability. Well-fed worms live for about three weeks, but dauer larvae can live for at least two months without affecting post-dauer lifespan1. Mutations in daf-2 and age-1, which produce a dauer constitutive (Daf-C) phenotype, and in clk-1, which are believed to slow metabolism, markedly increase adult lifespan2. Here we show that a ctl-1 mutation reduces adult lifespan in otherwise wild-type animals and eliminates the daf-c and clk-1 -mediated extension of adult lifespan. ctl-1 encodes an unusual cytosolic catalase; a second gene, ctl-2, encodes a peroxisomal catalase. ctl-1 messenger RNA is increased in dauer larvae and adults with the daf-c mutations. We suggest that the ctl-1 catalase is needed during periods of starvation, as in the dauer larva, and that its misexpression in daf-c and clk-1 adults extends lifespan. Cytosolic catalase may have evolved to protect nematodes from oxidative damage produced during prolonged dormancy before reproductive maturity, or it may represent a general mechanism for permitting organisms to cope with the metabolic changes that accompany starvation.
251 citations
TL;DR: In this paper, the apparent solubilities of schwertmannite and ferrihydrite were estimated from the H+, OH−, Fe3+, and SO42− activities of the natural stream waters in Korea and mine drainage in Ohio, USA.
245 citations
TL;DR: Findings indicate that NO protects against PC12 cell death by inhibiting the activation of caspase proteases through cGMP production and activation of protein kinase G.
Abstract: Although nitric oxide (NO) induces neuronal cell death under some conditions, it also can prevent apoptosis resulting from growth factor withdrawal. We investigated the molecular mechanism by which NO protects undifferentiated and differentiated PC12 cells from trophic factor deprivation-induced apoptosis. PC12 cells underwent apoptotic death in association with increased caspase-3-like activity, DNA fragmentation, poly(ADP-ribose) polymerase (PARP) cleavage, and cytochrome c release after 24 hr of serum withdrawal. The apoptosis of PC12 cells was inhibited by the addition of NO-generating donor S-nitroso-N-acetylpenicillamine (SNAP) (5-100 microM) and the specific caspase-3-like protease inhibitor Ac-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-cho) but not the YVADase (or caspase-1-like protease) inhibitor N-acetyl-Tyr-Val-Ala-Asp-aldehyde (Ac-YVAD-cho). SNAP and Ac-DEVD-cho prevented the increase in DEVDase (caspase-3-like protease) activity. The SNAP-mediated suppression of DEVDase activity was only minimally reversed by the incubation of cell lysate with dithiothreitol, indicating that NO did not S-nitrosylate caspase-3-like proteases in PC12 cells. Western blot analysis showed that NO inhibited the proteolytic activation of caspase-3. The cGMP analog 8-bromo-cGMP (8-Br-cGMP) blocked apoptotic cell death, caspase-3 activity and activation, and cytochrome c release. The soluble guanylyl cyclase inhibitor 1-H-oxodiazol-[1,2,4]-[4,3-a] quinoxaline-1-one (CODQ) significantly attenuated NO-mediated, but not 8-Br-cGMP-dependent, inhibition of apoptotic cell death, PARP cleavage, cytochrome c release, and DEVDase activity. Furthermore, the protein kinase G inhibitor KT5823 reversed both SNAP- and 8-Br-cGMP-mediated anti-apoptotic events. All these apoptotic phenomena were also suppressed by NO production through neuronal NO synthase gene transfer into PC12 cells. Furthermore, similar findings were observed in differentiated PC12 cells stimulated to undergo apoptosis by NO donors and NGF deprivation. These findings indicate that NO protects against PC12 cell death by inhibiting the activation of caspase proteases through cGMP production and activation of protein kinase G.
222 citations
TL;DR: Using water concentration as an exposure estimate can introduce misclassification of exposure for DBPs whose primary route is ingestion due to the great variability in the amount of water ingested across a population.
Abstract: Exposure to disinfection by-products (DBPs) of drinking water is multiroute and occurs in households serviced by municipal water treatment facilities that disinfect the water as a necessary step to halt the spread of waterborne infectious diseases. Biomarkers of the two most abundant groups of DBPs of chlorination, exhaled breath levels of trihalomethanes (THMs) and urinary levels of two haloacetic acids, were compared to exposure estimates calculated from in-home tap water concentrations and responses to a questionnaire related to water usage. Background THM breath concentrations were uniformly low. Strong relationships were identified between the THM breath concentrations collected after a shower and both the THM water concentration and the THM exposure from a shower, after adjusting for the postshower delay time in collecting the breath sample. Urinary haloacetic acid excretion rates were not correlated to water concentrations. Urinary trichloroacetic acid excretion rates were correlated with ingestion exposure, and that correlation was stronger in a subset of individuals who consumed beverages primarily within their home where the concentration measurements were made. No correlation was observed between an average 48-hr exposure estimate and the urinary dichloroacetic acid excretion rate, presumably because of its short biological half-life. Valid biomarkers were identified for DBP exposures, but the time between the exposure and sample collection should be considered to account for different metabolic rates among the DBPs. Further, using water concentration as an exposure estimate can introduce misclassification of exposure for DBPs whose primary route is ingestion due to the great variability in the amount of water ingested across a population.
158 citations
TL;DR: It was found that isoflavones including daidzein and tectorigenin possessed the inhibitory activity on cyclooxygenase, although the potency of inhibition was far less than that of indomethacin.
Abstract: Various flavonoid derivatives were previously reported to possess the inhibitory activity on cyclooxygenase/lipoxygenase. And these properties of flavonoids might contribute to their antiinflammatory activityin vivo. In this study, several polyhydroxylated/methoxylated flavonoid derivatives such as oroxylin A, wogonin, skullcapflavone II, tectorigenin and iristectorigenin A were isolated from the medicinal plants. These compounds were evaluated for their inhibitory effects on cyclooxygenase/lipoxygenase from the homogenate of human plateletsin vitro. It was found that isoflavones including daidzein and tectorigenin possessed the inhibitory activity on cyclooxygenase, although the potency of inhibition was far less than that of indomethacin. In addition, oroxylin A, baicalein and wogonin inhibited 12-lipoxygenase activity without affecting cyclooxygenase, which suggested that 5,6,7- or 5,7,8-trisubstitutions of A-ring of flavone gave favorable results. The IC50 values of oroxylin A and NDGA aginst 12-lipoxygenase were found to be 100 and 1.5 uM, respectively.
144 citations
TL;DR: Rutaecarpine showed in vivo anti-inflammatory activity on rat γ-carrageenan induced paw edema by intraperitoneal administration and could be attributed at least in part by inhibition of COS-2.
Abstract: Objective and Design: We investigated the effect of a new class of COX-2 inhibitor, rutaecarpine, on the production of PGD2 in bone marrow derived mast cells (BMMC) and PGE2 in COX-2 transfected HEK293 cells Inflammation was induced by γ-carrageenan in male Splague-Dawley (SD) rats¶Material: Rutaecarpine (8,13-Dihydroindolo[2',3':3,4]pyridol[2,1-b]quinazolin-5(7H)-one) was isolated from the fruits of Evodia rutaecarpa BMMC were cultured with WEHI-3 conditioned medium c-Kit ligand and IL-10 were obtained by their expression in baculovirus¶Methods: The generation of PGD2 and PGE2 were determined by their assay kit COX-1 and COX-2 protein and mRNA expression was determined by BMMC in the presence of KL, LPS and IL-10¶Treatment: Rutaecarpine and indomethacin dissolved in 01% carboxymethyl cellulose was administered intraperitoneally and, 1h later, γ-carrageenan solution was injected to right hind paw of rats Paw volumes were measured using plethysmometer 5h after γ-carrageenan injection¶Results: Rutaecarpine inhibited COX-2 and COX-1 dependent phases of PGD2 generation in BMMC in a concentration-dependent manner with an IC50 of 028 μM and 87 μM, respectively It inhibited COX-2-dependent conversion of exogenous arachidonic acid to PGE2 in a dose-dependent manner by the COX-2-transfected HEK293 cells However, rutaecarpine inhibited neither PLA2 and COX-1 activity nor COX-2 protein and mRNA expression up to the concentration of 30 μM in BMMC, indicating that rutaecarpine directly inhibited COX-2 activity Furthermore, rutaecarpine showed in vivo anti-inflammatory activity on rat γ-carrageenan induced paw edema by intraperitoneal administration¶Conclusion: Anti-inflammatory activity of Evodia rutaecarpa could be attributed at least in part by inhibition of COS-2
137 citations
TL;DR: Reverse transcription and polymerase chain reaction (RT-PCR) was used for detection and identification of three cucumoviruses in various plants sources with a single pair of primers, designed as CPTALL-3 and CPTall-5, indicating that the designed primers are only specific for the Cucumovirus genus.
133 citations
TL;DR: The sustained-release HPMC matrix tablet with optimizing formulations may provide an alternative for oral controlled delivery of MT and be helpful in the future treatment of circadian rhythmic disorders.
Abstract: A hydroxypropyl methylcellulose (HPMC) matrix tablet containing melatonin (MT) was formulated as a function of HPMC viscosity, drug loading, type and amount of disintegrant, lubricant and glidant, ...
123 citations
TL;DR: It is shown that dietary Se attenuated methamphetamine neurotoxicity and that this protection involves GPx-mediated antioxidant mechanisms.
TL;DR: It was found that pH control definitely affects mycelial cell growth and exopolysaccharide (EPS) production of theMycelial cultivation of Ganoderma lucidum and it was proved that bistage pH control retained the desirable morphologies of the mycelia during cultivation and resulted in low viscosity and yield stress of the culture broth.
TL;DR: The current dual drug-loaded HPMC matrix tablet, showing biphasic release profiles may provide an alternative to deliver drugs with circadian rhythmic behaviors in the body but needs to be further validated in future in human studies.
TL;DR: The method proposed can be used to improve the efficiency of three- or multi-axis milling and to generate optimal cutter paths and cutting conditions, according to given cutting conditions and cutter types.
Abstract: It is difficult to evaluate surface error in three- or multi-axis milling due to the complexity of the machining geometry. This paper presents texture superposition method to evaluate the surface asperity of milled surfaces. In order to derive overall surface generation mechanism of three different types of endmill cutters including a ball endmill, a filleted (torus-shaped) endmill, and a flat endmill, a generalized cutter model is proposed by introducing the fillet radius as a variable. The surface roughness is determined by the maximum height of the effective scallop including the effects of cutter marks and conventional scallops. The runout effect caused by the geometric inaccuracy of a cutter is added to make the predicted surface closer to the actual machined surface. Through these steps, three-dimensional surface topography, according to given cutting conditions and cutter types, can be formed. From machining experiments with a three-axis machining center, validity of the developed method was verified. The method proposed in this paper can be used to improve the efficiency of three- or multi-axis milling and to generate optimal cutter paths and cutting conditions.
TL;DR: Results indicate that ginkgetin may be a potential antiarthritic agent having analgesic activity and a dose-dependent inhibition in an animal model of acetic acid-induced writhing.
Abstract: Ginkgetin, a biflavone isolated from Ginkgo biloba leaves, was previously reported as an inhibitor of group II phospholipase A2. In this study, ginkgetin was evaluated for in vivo antiarthritic and analgesic activities. Ginkgetin (10-20 mg/kg/day) strongly reduced arthritic inflammation in an animal model of rat adjuvant-induced arthritis (86% inhibition at 16 days at a dose of 20 mg/kg/day) via intraperitoneal injection, while prednisolone (5 mg/kg/day) showed 79% reduction. Histological examination of the knee joints confirmed our findings. When analgesic activity was measured, ginkgetin showed a dose-dependent inhibition in an animal model of acetic acid-induced writhing. ED50 values for ginkgetin and indomethacin were 8.9 and 3.8 mg/kg, respectively. All these results indicate that ginkgetin may be a potential antiarthritic agent having analgesic activity.
TL;DR: The data suggest that TGase 2 can play a role in the acquisition of drug resistance in PC-14 cells through a general cellular defense system other than the MDR-related system.
Abstract: Recently a role for transglutaminase 2 (TGase 2) in the drug resistance of cancer cells has been suggested, although the mechanism is unclear. In the present study, we observed that doxorubicin-resistant PC-14/ADR cells showed a ten-fold higher level of TGase 2 expression than drug-sensitive PC-14 cells. PC-14/ADR cells exhibited the classical multidrug resistance (MDR) phenotype, which was cross-resistant to vincristine, but not to cisplatin. The stepwise induction of resistance to doxorubicin and vincristine in PC-14 cells was accompanied by a gradual increase of TGase 2 expression, but this expression was not increased with induction of cisplatin resistance. To confirm the role of TGase 2 protein in the acquisition of drug resistance in PC-14 cells, the TGase 2 expression in PC-14/ADR cells was reduced by stable transfection with the antisense or ribozyme construct. In the clones showing reduced expression of TGase 2, lactate dehydrogenase released from drug-treated cells was increased in the presence of either MDR-related drugs (doxorubicin and vincristine) or a non-MDR-related drug (cisplatin). These data suggest that TGase 2 can play a role in the acquisition of drug resistance in PC-14 cells through a general cellular defense system other than the MDR-related system.
TL;DR: In this paper, the performance of polymer-modified asphalt mixtures and specially designed reinforcement techniques against reflection cracking for the typical asphalt pavement overlays was evaluated and the effectiveness of the devised crack preventing techniques was evaluated.
TL;DR: In this paper, a comprehensive finite difference model is developed and presented to predict concentration polarization (CP) in commercial spiral wound membranes by solving the non-conservative mass balance equation in the feed channel employing fluid flow profiles based on feed spacer mixing.
TL;DR: The results suggest that the metastasis suppressing function of nm23-H1 is independent of the NDPK enzymatic activity.
TL;DR: In this article, a structural-acoustic response model is proposed to reduce the interior noise in a vehicle passenger compartment, in which the interior pressure is explicitly described in terms of the modal parameters and structural acoustic coupling coefficients of the car body and compartment system.
TL;DR: In conclusion, SDPP and WG appear to be excellent alternative protein sources for the early-weaned pigs.
TL;DR: In this article, thin-film cathode was deposited onto sintered alumina and substrates and showed improved electrochemical properties, such as peak potential divergence and rate capability, over those for the alumina substrate electrode.
Abstract: An thin‐film cathode was deposited onto sintered alumina and substrates. After annealing at in for , the film deposited on alumina consisted of large particles with several cracks, whereas the film deposited on the substrate was composed of very small and uniform particles. The films deposited on showed improved electrochemical properties, such as peak potential divergence and rate capability, over those for the alumina substrate electrode, which can be attributed to differences of the particle size, surface morphology, and the low electrical resistance of the current collector. ©1999 The Electrochemical Society
TL;DR: This molecule was found to have a broad antibacterial spectrum against not only Gram‐negative, but also Gram‐positive bacteria, and showed antifungal activity against Candida albicans.
TL;DR: In this paper, the effects of RuO2 addition on the barrier properties of the Ta layer were investigated at the temperature range of 650-800°C in air, and the thermal stability for the Pt/Ta+RuO2+TiSi2/poly-Si/SiO2/Si
Abstract: The effects of RuO2 addition on the barrier properties of the Ta layer were investigated at the temperature range of 650–800 °C in air. For the Pt/Ta/TiSi2/poly-Si/SiO2/Si structure, its layer structure was completely collapsed after annealing at 650 °C, resulting in higher total resistance and Schottky characteristics. For the Pt/Ta+RuO2/TiSi2/poly-Si/SiO2/Si structure, however, it exhibited the lower total resistance and ohmic characteristics, and its layer structure was retained up to 800 °C. A Ta amorphous structure by the chemically strong Ta–O or Ta–Ru–O bonds and nonstoichiometric, nanocrystalline RuOx resulted in the formation of a conductive RuO2 phase in the Ta+RuO2 barrier film after an annealing, leading to the prevention of the interdiffusion of Pt, Si, and external oxygen through the diffusion barrier as well as surface oxidation up to 800 °C. Therefore, the thermal stability for the Pt/Ta+RuO2/TiSi2/poly-Si/SiO2/Si structure was higher than that for Pt/Ta/TiSi2/poly-Si/SiO2/Si structure.
TL;DR: The results suggest that the CA1 area is the critical site for mediating the putative neuroprotective effect induced by dextromethorphan.
TL;DR: Several steroidal saponins and triterpenoids showed significant inhibition of ear edema (20∼37% inhibition), though less potent than indomethacin and hydrocortisone.
Abstract: Certain steroids and triterpenoids isolated from diverse plant families were known to possess anti-inflammatory activity. In the course of finding new anti-inflammatory natural products, some steroidal and triterpenoid saponins were isolated and evaluated for their anti-inflammatory activity using in vivo mouse ear edema test. At the oral dose of 100 mg/kg, several steroidal saponins and triterpenoid saponins such as hederagenin glycosides showed significant inhibition of ear edema (20-37% inhibition), though less potent than indomethacin and hydrocortisone.
TL;DR: Thrombin is demonstrated to be an effective stimulus in inducing interleukin (IL)-8 expression in human monocytic cell line U937 and this role for thrombin may be further regulated by lymphokines and lipid mediators.
TL;DR: In this paper, the effects of gas flow on particle growth in silane RF discharges in a plasma chemical vapor deposition (PCVD) reactor with a shower-type powered electrode were studied using an in situ two-dimensional polarization-sensitive laser-light-scattering method.
Abstract: The effects of gas flow on particle growth in silane RF discharges in a plasma chemical vapor deposition (PCVD) reactor with a shower-type powered electrode are studied using an in situ two-dimensional polarization-sensitive laser-light-scattering method. Particle growth depends on both the production of short-lifetime radicals and the loss of neutral clusters in the radical production region around the plasma/sheath boundary near the powered electrode. Gas flow of a velocity above about 6 cm/s is effective in suppressing particle growth because of increase in loss of neutral clusters. Moreover, particles larger than 120 nm in size that flow to the plasma/sheath boundary near the grounded electrode are found to pass through the sheath. This implies that such particles may deposit on film surfaces for PCVD reactors with the shower-type powered electrode.
TL;DR: In this article, a series of 1,3-dialkyloxycalix[4]arene dibenzocrown ethers were synthesized in the fixed 1, 3-alternate conformation with good yields by the reaction of 1 3-dipropyloxycalice[4]-arenes with Dibenzodimesylate in the presence of caesium carbonate.
Abstract: A series of 1,3-dialkyloxycalix[4]arene dibenzocrown ethers were synthesized in the fixed 1,3-alternate conformation with good yields by the reaction of 1,3-dialkyloxycalix[4]arenes with dibenzodimesylate in the presence of caesium carbonate. The three dimensional 1,3-alternate conformation was confirmed by X-ray crystal structure. Upon two phase extraction, NMR studies on the ligand–metal complex, single ion and competitive ion transport experiments through a bulk liquid membrane, 1,3-dipropyloxycalix[4]arene dibenzocrown-6, in which two benzo groups are symmetrically attached to the crown-6 linkage, gave one of the most efficient and selective extractabilities for caesium ion over other alkali metal ions. From supported liquid membrane experiments using 1 and 3 as organic carriers, permeation coefficients of the caesium ion were estimated to be 0.42 and 0.27 cm h–1, respectively. The selectivity of caesium over sodium ion was observed to increase with permeation time.
Journal Article•
TL;DR: Fibrin as well as fibrinogen function as a stimulator to macrophages, and leukocyte integrin p150,95 ( CD11c/ CD18), not Mac-I (CD11b/CD18), is involved in mediating fibrIn stimulatory activity in macrophage.
Abstract: Fibrin derived from fibrinogen after thrombin cleavage plays an essential role in forming blood clots. Fibrin as well as fibrinogen is also involved in the induction of platelet aggregation, leukocyte cell adhesion and phagocytosis. An additional biological role of fibrin and fibrinogen is presented in this study. One of the proteolytic peptides of fibrin/fibrinogen, fragment E, and not fragment D, was able to stimulate rat peritoneal macrophages to express interleukin-6 (IL-6). The stimulation of fibrin/fibrinogen fragment E on macrophages appeared to work in a dose- and time-dependent manner. Adherent fibrin fragment E was able to stimulate IL-6 expression as well as IL-6 protein production. The effect of fibrin fragment E was inhibited by the addition of an excess amount of GPRP tetrapeptide, but not by GHRP, which are the amino acids derived from the amino terminus of fibrin alpha and beta chains, respectively. These results suggest that fibrin as well as fibrinogen function as a stimulator to macrophages, and leukocyte integrin p150,95 (CD11c/ CD18), not Mac-I (CD11b/CD18), is involved in mediating fibrin stimulatory activity in macrophages.