Publications (4)11.1 Total impact
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Article: High concentration of magnolol induces hepatotoxicity under serum-reduced conditions.
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ABSTRACT: Although magnolol is cytoprotective against warm ischemia/reperfusion injury, its effect on cold preservation has not been fully investigated. This study aimed at examining whether magnolol maintains the liver graft integrity after cold preservation and elucidating the underlying mechanisms in terms of apoptotic signaling under both normothermic and hypothermic conditions. After being preserved in Ringer's lactate (RL) at 4 degrees C for 6h ex vivo, the magnolol-treated grafts demonstrated significantly higher AST, ALT, and LDH levels in perfusates than those from negative controls. TUNEL staining showed no difference in the number of apoptotic nuclei in both groups, whereas a more intense apoptotic signal in magnolol-treated grafts was shown as compared with the controls. In vitro data showed no significant difference in viability of RL-preserved clone-9 hepatocytes between the magnolol-treated and control groups, while magnolol pretreatment at 30min before cold preservation prominently induced hepatocyte cell death. RT-PCR and Western blotting analyses revealed a suppression in Bcl-2, but an up-regulation in Bax expression in clone-9 cells after magnolol treatment. Magnolol suppressed the ratios of NF-kappaB to I-kappaBalpha protein contents and I-kappaBalpha phosphorylation induced by TNF-alpha, and potentiated mitochondrial cytochrome c release and subsequent caspase-3 cleavage. Conversely, caspase-3 inhibitor attenuated magnolol-induced hepatotoxicity. We concluded that magnolol could not protect liver grafts from cold ischemia/reperfusion injury. High concentration of magnolol under serum-reduced conditions attenuates NF-kappaB-mediated signaling and induces intrinsic apoptotic pathway, thereby inducing in vitro hepatotoxicity.Phytomedicine: international journal of phytotherapy and phytopharmacology 09/2009; 17(6):469-74. · 2.17 Impact Factor -
Article: Serum factors potentiate hypoxia-induced hepatotoxicity in vitro through increasing transforming growth factor-beta1 activation and release.
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ABSTRACT: Although transforming growth factor-beta (TGF-beta), a growth regulator of hepatocytes, induces cell death under pathological conditions, responsiveness of hepatocytes to hypoxic stimulus has not been fully defined. This study aimed at investigating the role of TGF-beta1 in hypoxia-induced hepatotoxicity using cultured clone-9 hepatocytes with or without serum supplementation. Presence of serum significantly potentiated hypoxia-induced hepatotoxicity after 72h of exposure, as evidenced by fluorescent viability stain and LDH cytotoxicity assay. Quantitative PCR showed that TGF-beta1 gene expression decreased, while ELISA revealed that latent TGF-beta1 in conditioned media prominently increased in serum-treated groups under hypoxia. Western blotting indicated that both type I and II receptors of TGF-beta were up-regulated in serum-free groups, but down-regulated in serum-treated groups under hypoxia. Smad2 phosphorylation was only detectable in cells supplemented with serum, and hypoxia potentiated the extent of Smad2 phosphorylation, implicating that the activated TGF-beta1 induces hepatotoxicity in an autocrine manner. Addition of exogenous TGF-beta1 deteriorated, while TGF-beta1 blockade by neutralizing antibody ameliorated hypoxia-induced hepatotoxicity with serum supplementation. Gelatine zymography and immunofluorescent stain evidenced that elevated MMP-2 and MMP-9 activity and serum-dependent CD44 expression and its membranous localization may contribute to TGF-beta1 activation. The results suggest that the mechanism governing TGF-beta activation plays a crucial role in hypoxia-induced hepatotoxicity. Thus, interventions on TGF-beta1 bioavailability and/or its cognate signaling may be of benefit in preventing hypoxia-related liver injuries.Cytokine 06/2009; 47(1):11-22. · 3.02 Impact Factor -
Article: Propofol pretreatment attenuates LPS-induced granulocyte-macrophage colony-stimulating factor production in cultured hepatocytes by suppressing MAPK/ERK activity and NF-kappaB translocation.
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ABSTRACT: Propofol (PPF), a widely used intravenous anesthetic for induction and maintenance of anesthesia during surgeries, was found to possess suppressive effect on host immunity. This study aimed at investigating whether PPF plays a modulatory role in the lipopolysaccharide (LPS)-induced inflammatory cytokine expression in a cell line of rat hepatocytes. Morphological observation and viability assay showed that PPF exhibits no cytotoxicity at concentrations up to 300 microM after 48 h incubation. Pretreatment with 100 microM PPF for 24 h prior to LPS stimulation was performed to investigate the modulatory effect on LPS-induced inflammatory gene production. The results of semi-quantitative RT-PCR demonstrated that PPF pretreatment significantly suppressed the LPS-induced toll-like receptor (TLR)-4, CD14, tumor necrosis factor (TNF)-alpha, and granulocyte-macrophage colony-stimulating factor (GM-CSF) gene expression. Western blotting analysis showed that PPF pretreatment potentiated the LPS-induced TLR-4 downregulation. Flow cytometrical analysis revealed that PPF pretreatment showed no modulatory effect on the LPS-upregulated CD14 expression on hepatocytes. In addition, PPF pretreatment attenuated the phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) and IkappaBalpha, as well as the nuclear translocation of NF-kappaB primed by LPS. Moreover, addition of PD98059, a MAPK kinase inhibitor, significantly suppressed the LPS-induced NF-kappaB nuclear translocation and GM-CSF production, suggesting that the PPF-attenuated GM-CSF production in hepatocytes may be attributed to its suppressive effect on MAPK/ERK signaling pathway. In conclusion, PPF as an anesthetic may clinically benefit those patients who are vulnerable to sepsis by alleviating sepsis-related inflammatory response in livers.Toxicology and Applied Pharmacology 07/2008; 229(3):362-73. · 4.45 Impact Factor -
Article: Heat preconditioning ameliorates hepatocyte viability after cold preservation and rewarming, and modulates its immunoactivity.
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ABSTRACT: Heat preconditioning significantly preserved liver graft function after cold preservation in animal experimental model. The elevation of heat shock protein 70 (HSP70) was claimed to play a critical role in protecting grafts against cold preservation-induced hepatocyte apoptosis. However, little is known about whether HSP70 also plays an immunomodulatory role in cold preserved cells. This study aimed at investigating the relationship between HSP70 protein and the immunoactivity in response to lipopolysaccharide (LPS) stimulation. A normal rat hepatocyte cell line was preserved with University of Wisconsin (UW) solution, Ringer's lactate solution (RL), and phosphate-buffered saline (PBS) at 4 degrees C. No significant morphological alteration was noted in UW-preserved cells after 24 h through phase-contrast microscopic observation and fluorescent viability stain. Western blotting showed a two-fold increase in the ratio of HSP70/Bax proteins in cells after 24 h of UW preservation. Heat preconditioning significantly enhanced the recovery of lactate dehydrogenase (LDH) activity in both RL- and UW-preserved cells that were stored for a period of 12 h or less. Moreover, heat preconditioning promoted HSP70 and NF-kappaB p50 nuclear translocation and suppressed the LPS-induced nuclear p50 accumulation in cells before UW preservation. Immunofluorescent stain revealed that the LPS-induced p50 protein redistribution to nuclear membrane might contribute to NF-kappaB activation, while heat preconditioning and UW cold preservation completely abrogated the p50 intranuclear redistribution. Thus NF-kappaB p50 might be responsible for the endotoxin tolerance induction. These findings strongly suggest that heat preconditioning not only preserves hepatocyte viability after cold preservation and rewarming, but also ameliorates its immunoactivity.Transplant Immunology 02/2008; 18(3):220-31. · 1.46 Impact Factor
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Institutions
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2008–2009
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Chang Gung Memorial Hospital
Taipei, Taipei, Taiwan
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