• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.242.2-243
• /
• 2002

We have previously reported that activation of $K^{+}$-$Cl^{-}$-cotransport (KCC) by N-ethylmaleimide (NEM) induces apoptosis through generation of reactive oxygen species (ROS) in HepG2 human hepatoblastoma cells. In this study we investigated the possible role of phospholipase $A_2$($PLA_2$)-arachidonic acid (AA) signals in the mechanism of the NEM actions. (omitted)

• Journal of Radiation Industry
• /
• v.3 no.1
• /
• pp.25-29
• /
• 2009

Microarrays can be used to screen thousands of binding events in a parallel and high throughput fashion and are of major importance in disease diagnosis and drug discovery. The use of radioisotope is conventionally regarded as one of the most sensitive detection methods. Atherosclerosis is a common disorder affecting arterial blood vessels. It happens when fat, cholesterol, and other substances made in the arterial blood vessels form a hard substances called plaque. Lipoprotein-associated phospholipase $A_2$ ($Lp-PLA_2$), a phospholipase $A_2$ enzyme, is used as a marker for cardiac disease. The detection of $Lp-PLA_2$ was accomplished by using radioactive [$^3H-acetyl$] PAF as a substrate and a feasibility study on RI biochip application to detection of $Lp-PLA_2$, a risk factors of atherosclerosis was performed. Inhibitive activity of a native plant extract was also determined by using the RI biochip. It was found to be applicable to a high-throughput screening of inhibitors for developing atherosclerosis therapeutic agents.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.1
• /
• pp.175-181
• /
• 1998

The relation between lipid peroxidation and thrombotic reaction were investigated in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10gm were randomly assigned to normal and STZ-induced diabetic group(DM). Diabetes was experimentally induced by intravenous injection of 55mg/kg of body weight of STZ in citrate buffer(pH 4.3) after 4 weeks feeding of basal diet. Animals were sacrificed at the 6th day of diabetic states. Body weight gains were lower in diabetic group after STZ injection. Serum levels of thiobarbituric acid reacting substances(TBARS) that were markedly increased in DM group compared with of normal group. TBARS levels of HDL and LDL were similar patterns to total TBARA of serum. Activities of platelet phospholipase A2(PLA2) were higher in diabetic group than those of normal group. Activities of platelet cyclooxygenase were 106% in DM group than normal group. Platelet thromboxane A2(TXA2) formation was increased in DM group than normal group. Production of aortic prostacyclin(PGI2) was lower in diabetic group than that of normal group. PGI2/TXA2 ratios were decreased by 55% in DM groups than those of normal group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stess which leads to acceleration of lipid peroxidation and platelet aggregability. In conclusion, accelerating effect of lipid peroxidation and thrombogenesis in diabetic state is regareded to be resulted from enhancement of PLA2 activity and arachidonic acid metabolism, inhibition of antiaggrgating agent and aortic PGI2 formation.

• The Korean Journal of Physiology and Pharmacology
• /
• v.2 no.5
• /
• pp.601-609
• /
• 1998

The present study was undertaken to examine the role of phospholipase $A_2\;(PLA_2)$ in oxidant-induced inhibition of phosphate transport in primary cultured rabbit renal proximal tubule cells. Uptakes of phosphate and glucose were dose-dependently inhibited by an oxidant t-butylhydroperoxide (tBHP), and the significant inhibition appeared at 0.025 mM of tBHP, whereas tBHP-induced alterations in lipid peroxidation and cell viability were seen at 0.5 mM. tBHP stimulated arachidonic acid (AA) release in a dose-dependent fashion. A $PLA_2$ inhibitor mepacrine prevented tBHP-induced AA release, but it did not alter the inhibition of phosphate uptake and the decrease in cell viability induced by tBHP. tBHP-induced inhibition of phosphate transport was not affected by a PKC inhibitor, staurosporine. tBHP at 0.1 mM did not produce the inhibition of $Na^+-K^+-ATPase$ activity in microsomal fraction, although it significantly inhibited at 1.0 mM. These results suggest that tBHP can inhibit phosphate uptake through a mechanism independent of $PLA_2$ activation, irreversible cell injury, and lipid peroxidation in primary cultured rabbit renal proximal tubular cells.

• Journal of Life Science
• /
• v.21 no.8
• /
• pp.1100-1108
• /
• 2011

The immunomodulating effects of moxifloxacin seem to be effective in downregulating inflammatory reactions. This presumed effect was tested in endotoxin (ETX)-induced acute lung injury (ALI) in rats. After moxifloxacin treatment (10 mg/kg) of ETX-given rats, lung myeloperoxidase (MPO) activity, bronchoalveolar-lavage (BAL) protein, and the number of neutrophils in the BAL cells were measured. Light and electron microscopic structures were also examined. Electron microscopic $CeCl_3$ histochemistry for the detection of hydrogen peroxide in the lungs and immunohistochemistry of cytosolic phospholipase A2 (cPLA2) in the lung tissues and BAL cells were performed. To examine the expression of TNF${\alpha}$ in the lungs, western blotting was carried out with the lung tissues. ETX had accumulated neutrophils in the lungs, which was followed by lung leak. Oxidative stress occurred, and increased expression of cPLA2 in the lung tissues and BAL cells was observed in the ETX-given rats. Simultaneously, the expression of TNF${\alpha}$ was enhanced by ETX. Moxifloxacin, however, decreased all these parameters, indicating that ALI may have been ameliorated. Moxifloxacin appears to ameliorate ETX-induced ALI partially through the suppression of cPLA2 in the lungs of rats.

• The Korean Journal of Zoology
• /
• v.38 no.4
• /
• pp.457-464
• /
• 1995

Hela cells, a transformed human epithelial cell line, attach to various substrata but subsequent spreading is specific to collagen or gelatin. The spreading is initiated by the activation of phospholipase $A_2$ (PLA$_2$) which produces arachidonic acid (AA) as a consequence of cell surface collagen receptor clustering. This study examines the mechanism of PLA$_2$activation and which phospholipids are hydrolyzed by PIA$_2$ to release AA in response to Hela cell adhesion to a gelatin substratum. The levels of phosphatidyicholine decreases, among various phospholipids, during attachment and spreading of Hela cells. Lysophosphatidyicholine Is the only lysophospholipids formed during ileLa cell adhesion indicating that clustered collagen receptors activate PLA$_2$to hydrolyze posphatidylcholine to AA and lysophosphatidylcholine. Among various molecular entitles which are known to regulate PLA$_2$ activation, we have previously shown that PLA2 activation is not mediated by either changes in $Ca_2$+ levels, alkalinization of cytoplasmic p11, or activation of protein hinase C. It is also likely that PIA2 activation is not mediated by either pertussis or cholera toxinsensitive G proteins as those toxins do not affect both AA release and cell spreading.

• BMB Reports
• /
• v.30 no.2
• /
• pp.101-105
• /
• 1997

Extracellular phospholipase $A_2$ activity has been detected in urine of patients with acute pyelonephritis (APN). This enzyme required micromolar $Ca^{2+}$ ion for its maximum activity and showed a broad range of pH (4.5~10) optimum. Urine enzyme hydrolyzed phosphatidylethanolamine (PE) and phosphatidylserine (PS) more effectively than phosphatidylcholine (PC). $PLA_2$ activity in the urine of patients with APN was about 5-fold higher than that of healthy individuals. When urine was subjected to heparinSepharose column chromatography, phospholipase $A_2$ activity was detected in both heparin-non-binding and binding fractions. Both phospholipase $A_2$ activities were sensitive less than a micromolar calcium concentration and did not react with anti-human 14-kDa group II phospholipase $A_2$ monoclonal antibody, HP-l. These findings suggest that two kinds of novel extracellular phospholipase $A_2$. which may not belong to the 14-kDa group II phospholipase $A_2$ family, exist in the urine of patients with APN.

• Korean journal of applied entomology
• /
• v.55 no.2
• /
• pp.129-138
• /
• 2016

Eicosanoids are a group of C20 oxygenated polyunsaturated fatty acids (PUFAs). To monitor biosynthetic precursors of these PUFAs, this study extracted fatty acids from different tissues of the beet armyworm, Spodoptera exigua, and assessed their compositions using GC/MS. Fifth instar larvae were dissected to isolate different tissues of gut, fat body, hemocytes, and integument. From each tissue, total lipids were extracted and fractionated into neutral lipid (NL), glycolipid (GL), and phospholipid (PL). Most tissues contained palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2), and linolenic acid (18:3). However, their compositions were different among tissues and lipid types. Fat body and hemocytes possessed other type of fatty acids such as myristic acid (14:0) and three unknown fatty acids. Among lipid types, PL contained relatively high levels of linolenic acid than NL and GL, while it had lower saturated fatty acids. Total unsaturated fatty acid composition was varied among tissues and lipid types. PL was rich in unsaturated fatty acids in fat body, gut, and hemocytes. There was a significant influence of calcium-independent phospholipase $A_2$ ($iPLA_2$) on maintaining fatty acid composition because RNA interference of $iPLA_2$ expression significantly modified fatty acid compositions in NL and PL. However, this study did not detect arachidonic acid, a main eicosanoid biosynthesis precursor, in all tissues. This suggests an alternative biosynthesis of eicosanoids in insects, which is distinct from the biosynthetic pathway of mammals.

• Journal of Acupuncture Research
• /
• v.21 no.5
• /
• pp.179-190
• /
• 2004

Objectives : The purpose of this study was to investigate the effect of Bee Venom and Melittin acupuncture solution on the lipopolysaccharide and sodium nitroprusside- induced expression of cytosolic phospholipase $A_2$, tumor necrosis factor-${\alpha}$ and calcium concentration in RAW 264.7 cells, a murine macrophage cell line. Methods : The expression of cytosolic phospholipase $A_2$ and tumor necrosis factor-${\alpha}$ was determined by western blotting with corresponding antibodies, and the generation of intracellular calcium concentration was investigated by delta scan system in RAW 264.7 cells. Results : 1. Compared with control, expressions of lipopolysaccharide-induced cytosolic phospholipase $A_2$ were decreased significantly by $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution and decreased by 0.5, $1{\mu}g/mL$ of bee venom. 2. Compared with control, expressions of sodium nitroprusside-induced phospholipase $A_2$ were decreased significantly by 0.5, 1, $5{\mu}g/mL$ of bee venom and by 5, $10{\mu}g/mL$ of melittin acupuncture solution. 3. Compared with control, expressions of lipopolysaccharide-induced tumor necrosis factor-${\alpha}$ were decreased significantly by $10{\mu}g/mL$ of melittin acupuncture solution and were not changed significantly by 0.5, 1, $5{\mu}g/mL$ of bee venom and $5{\mu}g/mL$ of melittin acupuncture solution. 4. Compared with control, expressions of sodium nitroprusside-induced tumor necrosis factor-${\alpha}$ were decreased significantly by 1, $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution and decreased by $0.5{\mu}g/mL$ of bee venom 5. Compared with control, lipopolysaccharide-induced intracellular calcium concentrations were decreased by 0.5, 1, $5{\mu}g/mL$ of bee venom and $10{\mu}g/mL$ of melittin acupuncture solution and increased by $5{\mu}g/mL$ of melittin acupuncture solution. 6. Compared with control, sodium nitroprusside-induced intracellular calcium concentrations were decreased by 0.5, 1, $5{\mu}g/mL$ of bee venom and 5, $10{\mu}g/mL$ of melittin acupuncture solution.

• Korean journal of applied entomology
• /
• v.50 no.2
• /
• pp.107-113
• /
• 2011

Benzylideneacetone (BZA) is a compound derived from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila (Xn). Its immunosuppressive activity is caused by its inhibitory activity against eicosanoid biosynthesis. This BZA is being developed as an additive to enhance control efficacy of other commercial microbial insecticides. This study was focused on the enhancement of the immunosuppressive activity of BZA by generating its chemical derivatives toward decrease of its hydrophobicity. Two hydroxylated BZA and one sugar-conjugated BZA were chemically synthesized. All derivatives had the inhibitory activities of BZA against phospholipase $A_2$ ($PLA_2$) and phenoloxidase (PO) of the diamondback moth, Plutella xylostella, but BZA was the most potent. Mixtures of any BZA derivative with Bacillus thuringiensis (Bt) significantly increased pathogenicity of Bt. BZA also inhibited colony growth of four plant pathogenic fungi. However, BZA derivatives (especially the sugar-conjugated BZA) lost the antifungal activity. These results indicated that BZA and its derivatives inhibited catalytic activities of two immune-associated enzymes ($PLA_2$ and PO) of P. xylostella and enhanced Bt pathogenicity. We suggest its use to control plant pathogenic fungi.