Browsing by Author "Hung, YC"

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Cholesterol loading augments oxidative stress in macrophages
(2006-02-06)
Hung, YC
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Hong, MY
;
Huang, GS
;
材料科學與工程學系奈米科技碩博班
;
Graduate Program of Nanotechnology , Department of Materials Science and Engineering
To investigate the molecular consequence of loading free cholesterol into macrophages, we conducted a large-scale gene expression study to analyze acetylated-LDL-laden foam cells (AFC) and oxidized-LDL-laden foam cells (OFC) induced from human THP-1 cell lines. Cluster analysis was performed using 9600-gene microarray datasets from time course experiment. AFC and OFC shared common expression profiles; however, there were sufficient differences between these two treatments that AFC and OFC appealed as two separate entities. We identified 80 commonly upregulated genes and 48 commonly downregulated genes in AFC and OFC. Functional annotation of the differentially expressed genes indicated that apoptosis, extracellular matrix, oxidative stress, and cell proliferation was deregulated. We also identified 87 differentially expressed genes unique for AFC and 31 genes for OFC. The uniquely expressed genes of AFC are associated with kinase activity, ATP binding activity, and transporter activity, while unique genes for OFC are associated with cell signaling and adhesion. To validate the hypothesis that oxidative stress is a common feature for AFC and OFC, we performed a cluster analysis employing the genes related to oxidative stress, but we were unable to distinguish AFC from OFC in this manner. We performed real-time RTPCR and ELISA on foam cells to examine the transcripts and secreted protein of interleukin 1 beta (IL1 beta). IL1 beta was rapidly induced in foam cells, but for AFC both RNA level and protein level dropped immediately and was attenuated. To detect levels of reactive oxygen species in foam cells we conducted hydroethidine staining and observed high levels of superoxide anion. We conclude that loading free cholesterol induces high levels of superoxide anion, increases oxidative stress, and triggers a transient inflammatory response in macrophages. (c) 2006 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.
Inhibitory effects on phospholipase A2 and antivenin activity of melanin extracted from Thea sinensis Linn
(2004-03-05)
Hung, YC
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Sava, V
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Hong, MY
;
Huang, GS
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材料科學與工程學系奈米科技碩博班
Antivenin activity of melanin extracted from black tea (MEBT) was reported for the first time. The antagonistic effect of MEBT was evaluated for Agkistrodon contortrix laticinctus (broadbanded copperhead), Agkistrodon halys blomhoffii (Japanese mamushi), and Crotalus atrox (western diamondback rattlesnake) snake venoms administered i.p. to ICR mice. MEBT was injected i.p. immediately after the venom administration in dose of 3 mg per mouse in the same place of venom injection. MEBT demonstrated neutralization effect against all venoms tested. The greatest antivenin effect of MEBT was found against Japanese mamushi snake venom. In this case, half the mice died within 2.5 +/- 0.7 h after injection of 0.9 mg/kg of venom. An immediate injection of MEBT substantially reduced the toxic effect of venom and extended time at the 50% level of survival up to 52.3 +/- 2.3 h. The antivenin activity of MEBT is due to chelating of Ca++ and non-specific binding of phospholipase A2. The inhibitory effect of MEBT on phospholipase A2 assessed for different venoms was similar to that obtained with pure enzyme. Low toxicity of MEBT in combination with its antagonistic activity against different venoms may allow effective life-saving treatment against snakebites. Such application of MEBT is important when identification of the snake is impossible or if specific treatment is unavailable. (C) 2004 Elsevier Inc. All rights reserved.
Microarray analysis of ovarian cancer
(2005)
Huang, GS
;
Hung, YC
;
Chen, A
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Hong, MY
;
材料科學與工程學系奈米科技碩博班
Microarray experiments were performed to normal ovaries, benign ovarian tumor and stage I and III of ovarian cancer. By treating benign ovarian tumor as pre-cancerous stage and comparing to later stages of ovarian cancer we identified 46 genes overly expressed in early-staged cancer. We also identified over-expressed genes at all stages of ovarian tumor/cancer. The over-expressed genes might be alternative candidates for developing early diagnostic markers. JUN and nuclear receptor subfamily genes were repeatedly identified in the group of down-regulated genes indicating their important regulatory roles in the oncogenesis of ovary.
Preventive effect of Thea sinensis melanin against acetaminophen-induced hepatic injury in mice
(2004-08-11)
Hung, YC
;
Sava, VM
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Makan, SY
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Hong, MY
;
Huang, GS
The preventive effect of Thea sinensis melanin (TSM) against overdoses of N-acetyl-p-aminophenol (NAPAP) was studied on ICR mice. Animals were given 400 mg/kg intraperitoneally (i.p.) of NAPAP, and TSM was injected i.p. in doses 10-40 mg/kg 2 h before intoxication. The protective effects were evidenced by a complete blockage of the NAPAP-induced elevation of plasma alanine aminotransferase (ALT) activity, decreased concentration of thiobarbituric acid reactive substances (TBARS) to the control level, and a partial prevention of reduced glutathione (GSH) depletion in the liver tissue. Preadministration of TSM also caused restoration of superoxide dismutase (SOD) activity and resumed content of coenzymes 09 and Q10. TSM by itself, however, did not affect the hepatic functional parameters, including serum ALT, TBARS, GSH, SOD, or coenzymes Q in the liver. Administration of TSM caused a dose-dependent inhibition of N-nitrosodimethylamine demethylase activity with ED50 of 15.8 mg/kg. Activities of ethoxyresorufin O-dealkylase and pentoxyresorufin O-alkylase isozymes were changed insignificantly. The immune suppressive effect of NAPAP on the in vivo antibody-forming cell responses was demonstrated using ICR-sensitized mice with sheep red blood cells. The joint effect of TSM and NAPAP indicated the capability of TSM to recover immunity of the animals to the level of intact mice. Results obtained demonstrate that TSM preadministration can prevent the multiple toxic effects of NAPAP.