• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1612-1614
• /
• 2004

The piezoelectric ceramics for AE-sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used 0.9Pb$(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ moi rate. MPB(morphotropic phase boundary) is defned in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application of AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for AE-signal of PD and arc detecting. The detection characteristic is evaluated wave form, frequency distribution.

• IMMUNE NETWORK
• /
• v.6 no.3
• /
• pp.117-122
• /
• 2006

Background: Caveolin, a family of integral membrane proteins are a principal component of caveolae membranes. In this study, we investigated the effect of p38 kinase on differentiation and on inflammatory responses in sodium nitroprusside (SNP)-treated chondrocytes. Methods: Rabbit articular chondrocytes were prepared from cartilage slices of 2-week-old New Zealand white rabbits by enzymatic digestion. SNP was used as a nitric oxide (NO) donor. In this experiments measuring SNP dose response, primary chondrocytes were treated with various concentrations of SNP for 24h. The time course of the SNP response was determined by incubating cells with 1mM SNP for the indicated time period $(0{\sim}24h)$. The cyclooxygenase-2 (COX-2) and type II collagen expression levels were determined by immunoblot analysis, and prostaglandin $E_2\;(PGE_2)$ assay was used to measure the COX-2 activity. The tyrosine phosphorylation of caveolin-1 was determined by immunoblot analysis and immunostaining. Results: SNP treatment stimulated tyrosine phosphorylation of caveolin-1 and activation of p38 kinase. SNP additionally caused dedifferentiation and inflammatory response. We showed previously that SNP treatment stimulated activation of p38 kinase and ERK-1/-2. Inhibition of p38 kinase with SB203580 reduced caveolin-1 tyrosine phosphorylation and COX-2 expression but enhanced dedifferentiation, whereas inhibition of ERK with PD98059 did not affect caveolin-1 tyrosine phosphorylation levels, suggesting that ERK at least is not related to dedifferentiation and COX-2 expression through caveolin-1 tyrosine phosphorylation. Conclusion: Our results indicate that SNP in articular chondrocytes stimulates dedifferentiation and inflammatory response via p38 kinase signaling in association with caveolin-1 phosphorylation.

• Annals of Hepato-Biliary-Pancreatic Surgery
• /
• v.28 no.1
• /
• pp.70-79
• /
• 2024

Backgrounds/Aims: After pancreatoduodenectomy (PD), an early oral diet is recommended; however, the postoperative nutritional management of PD patients is known to be highly variable, with some centers still routinely providing parenteral nutrition (PN). Some patients who receive PN experience clinically significant complications, underscoring its judicious use. Using a large cohort, this study aimed to determine the proportion of PD patients who received postoperative nutritional support (NS), describe the nature of this support, and investigate whether receiving PN correlated with adverse perioperative outcomes. Methods: Data were extracted from the Recurrence After Whipple's study, a retrospective multicenter study of PD outcomes. Results: In total, 1,323 patients (89%) had data on their postoperative NS status available. Of these, 45% received postoperative NS, which was "enteral only," "parenteral only," and "enteral and parenteral" in 44%, 35%, and 21% of cases, respectively. Body mass index < 18.5 kg/m² (p = 0.03), absence of preoperative biliary stenting (p = 0.009), and serum albumin < 36 g/L (p = 0.009) all correlated with receiving postoperative NS. Among those who did not develop a serious postoperative complication, i.e., those who had a relatively uneventful recovery, 20% received PN. Conclusions: A considerable number of patients who had an uneventful recovery received PN. PN is not without risk, and should be reserved for those who are unable to take an oral diet. PD patients should undergo pre- and postoperative assessment by nutrition professionals to ensure they are managed appropriately, and to optimize perioperative outcomes.

• Biomedical Science Letters
• /
• v.28 no.1
• /
• pp.25-33
• /
• 2022

The imbalance of oxidative stress due to the excessive production of reactive oxygen species (ROS) leads to the pathogenesis of liver disease. To prevent this, the role of antioxidant mechanisms is important. Antioxidant studies have been reported on the Filipendula glaberrima Nakai. However, studies applied to HepG2 cells, which are human liver cells, have not yet been conducted. In this study, 70% ethanol extract of Filipendula glaberrima Nakai (FGE) was prepared and antioxidant activity was investigated. It was confirmed whether FGE pretreatment could reduce hydrogen peroxide-induced oxidative stress in HepG2 cells. The increase in gene expression of antioxidant biomarkers and the scavenging ability of ROS were measured, and Hoechst 33342 staining was used to know the inhibitory effect of the apoptosis. As a result, FGE significantly increased SOD (2.6-fold), CAT (4.4-fold), MT-1A (3.1-fold), GPx (4-fold), and G6PD (2.4)-fold compared to the H₂O₂-treated group. FGE directly inhibited ROS production from 13.4 to 3.6 (the fluorescence mean of DCF-DA) and also reduced apoptotic cells from 45% to 10% (Hoechst 33342 staining) at 2.5 ㎍/mL. These results demonstrate the excellent antioxidant activity of FGE and show that it can be used as a functional food to prevent liver disease.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.6
• /
• pp.1170-1178
• /
• 2008

The cyclopentenone prostaglandins (cyPGs) prostaglandin $A_1$ ($PGA_1$) and 15-deoxy-${\Delta}^{12,14}$-prostaglandin $J_2$ (15d-$PGJ_2$) have been reported to exhibit antiinflammatory activity in activated monocytes/macrophages. However, the effects of these two cyPGs on the expression of cytokine genes may differ. In this study, we investigated the mechanism of action of $PGA_1$ in lipopolysaccharide (LPS)-induced expression of inter leu kin (IL)-10 mRNA in mouse peritoneal macrophages. 15d-$PGJ_2$ inhibited expression of LPS-induced IL-10, whereas $PGA_1$ increased LPS-induced IL-10 expression. This synergistic effect of $PGA_1$ on LPS-induced IL-10 expression reached a maximum as early as 2 h after simultaneous $PGA_1$ and LPS treatment ($PGA_1$/LPS), and did not require new protein synthesis. The synergistic effect of $PGA_1$ was inhibited by GW9662, a specific peroxisome proliferator-activated receptor ${\gamma}(PPAR{\gamma})$ antagonist, and Bay-11-7082, a NF-${\kappa}B$ inhibitor. The extracellular signal-regulated kinases (ERK) inhibitor PD98059 increased the expression of $PGA_1$/LPS-induced IL-10 mRNA, rather than inhibiting the IL-10 expression. Moreover, $PGA_1$ inhibited LPS-induced ERK phosphorylation. The synergistic effect of $PGA_1$ on LPS-induced IL-10 mRNA and protein production was inhibited by p38 inhibitor PD169316, and $PGA_1$ increased LPS-induced p38 phosphorylation. In the case of stress-activated protein kinase/c-Jun $NH_2$-terminal kinase (SAPK/JNK), the SAPK/JNK inhibitor SP600125 did not inhibit IL-10 mRNA synthesis but inhibited the production of IL-10 protein remarkably. These results suggest that the synergistic effect of $PGA_1$ on LPS-induced IL-10 expression is NF-${\kappa}B$-dependent and mediated by mitogen-activated protein (MAP) kinases, p38, and SAPK/JNK signaling pathways, and also associated with the $PPAR{\gamma}$ pathway. Our data may provide more insight into the diverse mechanisms of $PGA_1$ effects on the expression of cytokine genes.

• Polymer(Korea)
• /
• v.33 no.2
• /
• pp.158-163
• /
• 2009

In this study, we synthesized a series of dendritic polystyrene-b-linear poly (t-butyl acrylate) copolymers with well-defined molecular architectures. The hydroxyl group located at the focal point of the second generation dendron bearing polystyrene ($M_n$ = 1000 g/mol) peripheries was converted into amine group via the following stepwise reactions: 1) tosylatoin, 2) azidation, and 3) reduction. On the other hand, the linear poly (t-butyl acrylate)s were prepared by an atom transfer radical polymerization (ATRP) of t-butyl acrylate where benzyl 2-bromopropanoate and Cu(I)Br/PMDETA were used as initiator and catalyst, respectively. To convert the end group of prepared poly (t-butyl acrylate) s into carboxylic acid, a debenzylation was performed using Pd/C catalyst under $H_2$ atmosphere. In the final step, dendritic-linear block copolymers were obtained through a simple amide coupling reaction mediated by 4-(dimethylamino) pyridine(DMAP) and N,N'-diisopropylcarbodiimide(DIPC). The resulting diblock copolymers were shown to have well-defined molecular weights and narrow molecular weight distributions as supported by $^1H$-NMR spectroscopy and gel permeation chromatography(GPC).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.60-60
• /
• 2015

Nanosheets of graphene and related 2D materials have attracted much attention due to excellent physical, chemical and mechanical properties. Single-layer graphene (SLG) was first synthesized by Blakely et al in 1974 [1]. Following his achievements, we initiated the growth and characterization of graphene and h-BN on metal substrates using surface segregation and precipitation in 1980s [2,3]. There are three important steps for nanosheet growth; surface segregation of dopants, surface reaction for monolayer phase, and subsequent 3-D growth (surface precipitation). Surface phase transition was clearly demonstrated on C-doped Ni(111) by in situ XPS at elevated temperatures [4]. The growth mode was clarified by inelastic background analysis [5]. The surface segregation approach has been applied to C-doped Pt(111) and Pd(111), and controllable growth of SLG has been demonstrated successfully [6]. Recently we proposed a promising method for producing SLG fully covering an entire substrate using Ni films deposited on graphite substrates [7]. A universal method for layer counting has been proposed [8]. In this paper, we will focus on the effect of competitive surface-site occupation between carbon and other surface-active impurities on the graphene growth. It is known that S is a typical impurity of metals and the most surface-active element. The surface sites shall be occupied by S through surface segregation. In the case of Ni(110), it is confirmed by AES and STM that the available surface sites is nearly occupied by S with a centered $2{\times}2$ arrangement. When Ni(110) is doped with C, surface segregation of C may be interfered by surface active elements like S. In this case, nanoscopic characterization has discovered a preferred directional growth of SLG, exhibiting a square-like shape (Fig. 1). Also the detailed characterization methodologies for graphene and h-BN nanosheets, including AFM, STM, KPFM, AES, HIM and XPS shall be discussed.

• Environmental Analysis Health and Toxicology
• /
• v.20 no.1
• /
• pp.87-95
• /
• 2005

Cadmium is well known as a toxic metal and has insulin mimicking effects in rat adipose tissue. This study was undertaken to investigate the effect of CdCl₂ on glucose transport and its mechanism in 3T3 - L1 adipocytes. CdCl₂ exhibits respectively 2.2 and 2.8 fold increases in the 2-deoxyglucose uptake when exposed to 10 and 25 μM of CdCl₂ for 12 hr. To investigate the stimulating mechanism of glucose transport induced by CdCl₂. Wortmannin and PD98059 were used respectively as PI3K inhibitor and MAPK inhibitor, which did not affect 2-DOG uptake. This results suggest that induced 2-deoxy-(l-3H)-D-glucose (2-DOG) uptake by CdCl₂ may not be concerned with the insulin signalling pathway. Whereas nifedipine, a calcium channel blocker inhibited the 2- DOG uptake stimulated by CdCl₂. In addition, we also measured the increased production of Reactive oxygen substances (ROS) and glutathione (GSH) level in 3T3-L1 adipocytes to investigate correlation between the glucose uptake and increased production of ROS with H2DCFDA. CdCl₂ increased production of ROS. Induced 2-DOG uptake and increased production of ROS by CdCl₂ were decreased by N-acetylcystein (NAC). And L-buthionine sulfoximine (BSO) a potent inhibitor of γ-GCS, decreased of 2-DOG uptake. Also NAC and BSO changed the cellular GSH level, but GSH/GSSG ratio remained unchanged at 10, 25 μM of CdCl₂.

• Journal of Radiopharmaceuticals and Molecular Probes
• /
• v.1 no.2
• /
• pp.104-108
• /
• 2015

Human serum albumin (HSA) has potential for diagnosis and therapy in clinical setting. The purpose of experiments was to develop and evaluate $^{68}Ga$-HSA as a PET agent for diagnosis of acute inflammation. NOTA-HSA was synthesized by conjugating 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid to HSA in 0.1 M sodium carbonate buffer (pH 9.5) and then purified using a PD-10 size-exclusion column. NOTA-HSA was labeled with $^{68}Ga$ at room temperature for 10 min, and 8.4% sodium hydrogen carbonate buffer was added for neutralization. $^{68}Ga$-NOTA-HSA was purified using alumina N plus light cartridge and $0.22{\mu}m$ syringe filter. Labeling efficiency and radiochemical purity were determined by ITLC-SG with 0.1 M citric acid. Biodistribution study was performed in a male BALB/c mice model of Carrageenan-induced acute inflammation. Animal PET study was performed in acute inflammation mice model after tail vein injection of $^{68}Ga$-HSA. This radiotracer showed high labeling efficiency (>99%) around pH 7. Biodistribution study showed higher inflamed footpad uptake than control footpad uptake. Animal PET study revealed 2 times higher uptake on inflamed footpad compared to control footpad. In these experiments, we developed $^{68}Ga$-HSA for acute inflammation PET imaging and evaluated it in a mouse disease model. The results demonstrated that $^{68}Ga$-HSA has potential as a PET imaging agent for diagnosis of acute inflammation.

• Journal of the Korean Wood Science and Technology
• /
• v.19 no.4
• /
• pp.80-84
• /
• 1991

Lignocellulosic biomass including acetosolv ricestraw and spruce lignin were liquefied and converted into liquid hydrocarbons by catalytic hydroliquefaction reaction. These experimental works were carried out in 1-liter-capacity autoclave using 50% tetralin and m-cresol solution respectively as soluble solvent and Ni. Pd. Fe and red mud as catalyst. $H_2$ gas was supplied into the reactor for escaltion of deoxhydroenolysis reaction. Catalyst concentrations were 1 % of raw material based on weight. The ratio between raw materials and soluble solvent are 1g and 10cc. The reaction conditions are 400-$700^{\circ}C$ of reaction temperature, 10-50 atms of reaction pressure. The highest yield of hydrocarbon, so called "product oil" showed 32% and 5.5% of lowest char formation when red mud was used as catalyst. The product oil yields from those of other catalysts were in the range of 20-29%. The influence of different initial hydrogen pressures was examined in the range d 30-50 atms. A minimum pressure of 35 atms was necessary to obtain a complete recovery of souble solvent for recycling.