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Chen T.-S.,China Medical University at Taichung | Liou S.-Y.,Formosan Blood Purification Foundation | Wu H.-C.,China Medical University at Taichung | Tsai F.-J.,China Medical University at Taichung | And 4 more authors.
Food Chemistry | Year: 2012

Polyphenols, such as (-)-epigallocatechin gallate (EGCG), have pro-oxidant properties that lead to activation of the cellular apoptotic pathway; however, the mechanism underlying the induction of this pro-oxidant activity is unclear. We found intensive chemiluminescence for EGCG and hydroquinone (HQ) in the presence of amino acids with basic amino side-chains, such as arginine or lysine. In addition, the chemiluminescence of EGCG and arginine or lysine was totally suppressed by the addition of superoxide dismutase; whereas the chemiluminescence of HQ and arginine or lysine was totally suppressed by the addition of catalase. Furthermore, we found that polyphenols are capable of inducing oxidative stress, including depletion of albumin thiol content, elevation of plasma oxidized low-density lipoprotein and acceleration of cell death in the presence of arginine. Taking the results together, we suggest that amino acids with basic amino side-chain accelerate the production of reactive oxygen species in the presence of polyphenols. © 2012 Elsevier Ltd. All rights reserved.


Chen T.-S.,China Medical University at Taichung | Liou S.-Y.,Formosan Blood Purification Foundation | Wu H.-C.,China Medical University at Taichung | Tsai F.-J.,China Medical University at Taichung | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2010

Several analytical approaches are available for investigating the antioxidant power for antioxidants, and they are based on a variety of chemical principles, such as oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and ferric reducing/antioxidant power (FRAP). This paper reports a new rapid method for investigating antioxidant power on the basis of the electron-donating ability. This method is called chemiluminescence analysis of antioxidant power (CAAP). The electrons donated from antioxidants are capable of inducing chemiluminescence in the presence of lucigenin and a base. Thus, the intensity of chemiluminescence induced by antioxidants is proportional to their electron-donating ability (antioxidant power). It was found that the correlation between CAAP and FRAP was positive (r = 0.959) and statistically significant (p < 0.05). In addition to the FRAP assay, the rapid CAAP assay is convenient for investigating the antioxidant power of herbal extracts. © 2010 American Chemical Society.


Chen T.-S.,China Medical University at Taichung | Liou S.-Y.,Formosan Blood Purification Foundation | Wu H.-C.,China Medical University at Taichung | Tsai F.-J.,China Medical University at Taichung | And 4 more authors.
International Urology and Nephrology | Year: 2011

Uremic patients with hyperlipidemia are classified at high atherogenic risk due to oxidative stress induced by regular hemodialysis process (hemoincompatibility) and a high level of oxidized low-density lipoprotein (ox-LDL). This study aimed to investigate whether LDL apheresis was capable of reducing oxidative and atherogenic markers in uremic patients with hyperlipidemia. We found that oxidative metabolites (methylquanidine, dityrosine, and ox-LDL) and atherogenic markers (lipoprotein (a), LDL, and LDL/HDL ratio) were significantly reduced (P < 0.05) after LDL apheresis. On the other hand, plasma total antioxidant status (TAS) was not influenced after LDL apheresis. Our results suggest that LDL apheresis reduces oxidative and atherogenic markers and do not influence plasma TAS in uremic patients with hyperlipidemia. This may lead to a decreased risk of atherosclerosis in these patients. However, supplementation of dietary proteins may be necessary because of the removal of some "useful" proteins (e.g., albumin and globulin) after LDL apheresis. © 2010 Springer Science+Business Media, B.V.


Chen T.-S.,China Medical University at Taichung | Liou S.-Y.,Formosan Blood Purification Foundation | Wu H.-C.,China Medical University at Taichung | Tsai F.-J.,China Medical University at Taichung | And 4 more authors.
Journal of Medicinal Food | Year: 2011

Uremic patients with diabetes suffer from high levels of oxidative stress due to regular hemodialysis therapy (neutrophil activation induced by hemo-incompatibility between the hemodialyser and blood) and complications associated with diabetes. Several plasma biomarkers were screened in 13 uremic diabetic patients after receiving the mixture of (-)-epigallocatechin gallate (EGCG), a major component of green tea extract, and Amla extract (AE), from Emblica officinalis, the Indian gooseberry, for 3 months. We found that oral administration of a 1:1 mixture of EGCG and AE for 3 months significantly improved antioxidant defense as well as diabetic and atherogenic indices in uremic patients with diabetes. Furthermore, no significant changes in hepatic function, renal function, or inflammatory responses were observed. These results suggest that a 1:1 combination of EGCG and AE is a safe and effective treatment for uremic patients with diabetes. © 2011, Mary Ann Liebert, Inc.


PubMed | China Medical University at Taichung, Formosan Blood Purification Foundation, Chung Yuan Christian University and Asia University, Taiwan
Type: Journal Article | Journal: Food chemistry | Year: 2014

Hemodialysis can remove uremic solutes but this treatment induces oxidative stress in uremic patients because of hemo-incompatibility. Therefore, we hypothesised that an antioxidant dialysate (a dialysate containing antioxidant(s)) would provide antioxidant defence in uremic patients during hemodialysis. Several herbal extracts were studied and measurements of antioxidant power and stability assays indicated that epigallocatechin gallate (EGCG) was the best of those tested for use as an antioxidant dialysate (EGCG dialysate). We observed that EGCG dialysate could provide the highest level of antioxidant defence at a dialysate flow rate of 500 ml/min and a blood flow rate of 200 ml/min. In addition, some important parameters for hemodialysis were calculated for supporting the protective role of EGCG dialysate. This is the first description of the preparation of an antioxidant dialysate. We suggest that EGCG dialysate will reduce the level of oxidative stress in hemodialysis patients, leading to a decrease of complications associated with oxidative damage.


Chen T.-S.,Chung Yuan Christian University | Liou S.-Y.,Formosan Blood Purification Foundation | Chang Y.-L.,Chung Yuan Christian University
International Urology and Nephrology | Year: 2010

Background The purpose of this study was to evaluate two commercial hemodialyzers (F100 and P21) through the clearance of identified and unidentified uremic solutes. Methods We investigated plasma samples from healthy and uremic subjects. Results We found three unidentified uremic solutes (P1, P2, and P3) after HPLC analysis of plasma samples. Then, we determined the clearance of four identified and the three unidentified uremic solutes in patients with F100 and P21. There was no significance between F100 and P21 in clearance of four identified uremic solutes. By contrast, the clearance of P1 and P2 with F100 was superior with the P21 (P<0.05). Conclusion Our data suggest that selection of a hemodialyzer based on the clearance of identified uremic solutes might not be sufficient. Application of external techniques to determine additional external factors (i.e., clearance of unidentified uremic solutes) can facilitate a better decision in the selection of the ideal hemodialyzer. © Springer Science+Business Media, B.V. 2009.


PubMed | Bharathiar University, China Medical University at Taichung, Hungkuang University, Meiho University and 3 more.
Type: Journal Article | Journal: Luminescence : the journal of biological and chemical luminescence | Year: 2015

Topical hydroquinone serves as a skin whitener and is usually available in cosmetics or on prescription based on the hydroquinone concentration. Quantification of hydroquinone content therefore becomes an important issue in topical agents. High-performance liquid chromatography (HPLC) is the commonest method for determining hydroquinone content in topical agents, but this method is time-consuming and uses many solvents that can become an environmental issue. We report a rapid method for quantifying hydroquinone content by chemiluminescent analysis. Hydroquinone induces the production of hydrogen peroxide in the presence of basic compounds. Hydrogen peroxide induced by hydroquinone oxidized light-emitting materials such as lucigenin, resulted in the production of ultra-weak chemiluminescence that was detected by a chemiluminescence analyzer. The intensity of the chemiluminescence was found to be proportional to the hydroquinone concentration. We suggest that the rapid (measurement time, 60 s) and virtually solvent-free (solvent volume, <2 mL) chemiluminescent method described here for quantifying hydroquinone content may be an alternative to HPLC analysis.


PubMed | China Medical University at Taichung, Formosan Blood Purification Foundation and Chung Yuan Christian University
Type: Journal Article | Journal: Luminescence : the journal of biological and chemical luminescence | Year: 2016

Regular hemodialysis treatment induces an elevation in oxidative stress in patients with end-stage renal failure, resulting in oxidative damage of the most abundant serum protein, albumin. Oxidation of serum albumin causes depletion of albumin reactive thiols, leading to oxidative modification of serum albumin. The aim of this study was to screen the antioxidant capacity of albumins isolated from uremic patients (HD-ALB) or healthy volunteers (N-ALB). From high-performance liquid chromatography spectra, we observed that one uremic solute binds to HD-ALB via the formation of disulfide bonds between HD-ALB and the uremic solute. Furthermore, we found using chemiluminescent analysis that the antioxidant capacities for N-ALB to scavenge reactive oxygen species including singlet oxygen, hypochlorite and hydrogen peroxide were higher than HD-ALB. Our results suggest that protein-bound uremic solute binds to albumin via formation of disulfide bonds, resulting in the depletion of albumin reactive thiols. The depletion of albumin reactive thiols leads to a reduced antioxidant capacity of HD-ALB, implying postmodification of albumin. This situation may reduce the antioxidant capacity of albumin and increase oxidative stress, resulting in increase in complications related to oxidative damage in uremic patients. Copyright 2016 John Wiley & Sons, Ltd.


PubMed | China Medical University at Taichung, Chang Gung Memorial Hospital Keelung Branch, Chung Yuan Christian University and Formosan Blood Purification Foundation
Type: Journal Article | Journal: PloS one | Year: 2016

Elevated levels of advanced glycation end products (AGEs) within tissues may contribute to endothelial dysfunction, an early indicator of atherosclerosis. We aimed to investigate whether levels of skin AGEs could be a useful marker to predict endothelial dysfunction in uremic subjects on hemodialysis.One hundred and nineteen uremic patients on hemodialysis and 57 control subjects with moderate-to-high cardiovascular risk factors and without chronic kidney disease (CKD) were enrolled. We used ultrasound to measure flow-mediated vasodilation (FMD). An AGE reader measured skin autoflurorescence (AF). We then compared differences in FMD and skin AF values between the two groups. The uremic subjects had significantly higher levels of skin AF (3.470.76 AU vs. 2.210.45 arbitrary units; P<0.01) and significantly lower levels of FMD (4.79%1.88% vs. 7.19%2.17%; P<0.01) than the non-CKD subjects. After adjusting for all potential covariates, we found that skin AF level independently predicted FMD in both the hemodialysis and the non-CKD groups. In the hemodialysis group, skin AF 3.05 arbitrary units predicted abnormal FMD at a sensitivity of 87.9% and a specificity of 78.6% (P<0.01).Skin AF could be a useful marker to predict endothelial dysfunction in uremic subjects on hemodialysis.


Kuo C.-L.,China Medical University at Taichung | Chen T.-S.,China Medical University at Taichung | Liou S.-Y.,Formosan Blood Purification Foundation | Hsieh C.-C.,China Medical University at Taichung | Hsieh C.-C.,Tunghai University
Immunopharmacology and Immunotoxicology | Year: 2014

Green tea is a widely consumed beverage known for its beneficial anti-inflammatory, anti-oxidative, anti-mutagenic, anti-carcinogenic, and cardioprotective properties. Here, we administered epigallocatechin gallate fraction of green tea extract (EGTE) to mice for 6 weeks and examined the effects on the innate and adaptive immune responses by measuring phagocytic and natural killer (NK) cell activity, as well as antigen-specific proliferation, cytolysis, cytokine secretion, and antibody production. Our data show that EGTE administration increased NK cell cytolysis and peritoneal cell phagocytosis, as well as splenocyte proliferation and secretion of IL-2 and IFN-γ. Of note, EGTE treatment decreased the production antigen-specific IgE via increased the proportion of CD4+ CD25+ regulatory T lymphocytes in the spleen, suggesting that EGTE may play a role in regulating the allergic response. © 2014 Informa Healthcare USA, Inc. All rights reserved.

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