Mei-Ling Cheng

Chang Gung University, Hsin-chu-hsien, Taiwan, Taiwan

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Publications (56)261.13 Total impact

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    ABSTRACT: Amino acid-derived metabolites, including protein-bound uremic toxins, may have prognostic value for patients with heart failure (HF). The aim of this study was to investigate whether p-cresyl sulfate (PCS), indoxyl sulfate (IS), and arginine metabolites provided prognostic values in addition to the traditional biomarker, B-type natriuretic peptide (BNP), in patients with HF. Chromatography mass spectrometry was performed to measure tyrosine, tryptophan, arginine, PCS, IS, and asymmetric (ADMA) and symmetric dimethylarginine (SDMA) in the plasma from 51 normal controls and 136 HF patients. Compared to the normal controls, PCS levels significantly increased in HF patients (p = 0.003). During the follow-up (2.3 ± 1.1 years), 35 (25.7 %) patients experienced a composite event of death or HF-related re-hospitalization. In univariable analysis, PCS, estimated glomerular filtration rate (eGFR), BNP, DMA/arginine ratio, and ADMA/arginine ratio were associated with a higher rate of composite events. In the multivariable analysis, PCS was the only independent predictor of composite events [hazard ratio (HR) 1.06 (per 10 μM), 95 % confidence interval (CI) 1.01-1.11, p = 0.02]. Kaplan-Meier curves showed that a PCS level of ≥50 μM was significantly associated with a higher composite event rate than those with a PCS level of <50 μM (Log rank = 5.11, p = 0.024; HR 2.13, 95 % CI 1.09-4.16, p = 0.02). In conclusion, among protein-bound uremic toxins, eGFR, and DMA metabolites, increased PCS is the only independent predictor of HF-related events in patients with HF. A combination of PCS and BNP should better risk-stratify patients with HF.
    Heart and Vessels 07/2015; DOI:10.1007/s00380-015-0702-0 · 2.07 Impact Factor
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    ABSTRACT: This study was designed to investigate the effect of glucose 6-phosphate dehydrogenase (G6PD) deficiency on pro-inflammatory cytokine secretion using a palmitate-induced inflammation HepG2 in vitro model. The modulation of cellular pro-inflammatory cytokine expression under G6PD deficiency during chronic hepatic inflammation has never been investigated before. The culture medium of untreated and palmitate-treated G6PD-scramble (Sc) and G6PD-knockdown (Gi) HepG2 cells were subjected to cytokine array analysis, followed by validation with ELISA and qRT-PCR of the target cytokine. The mechanism of altered cytokine secretion in palmitate-treated Sc and Gi HepG2 cells was examined in the presence of anti-oxidative enzyme (glutathione peroxidase, GPX), anti-inflammatory agent (curcumin), NF-κB inhibitor (BAY11-7085) and specific SiRNA against NF-κB subunit p65. Cytokine array analysis indicated that IL-8 is most significantly increased in G6PD-knockdown HepG2 cells. The up-regulation of IL-8 caused by G6PD deficiency in HepG2 cells was confirmed in other G6PD-deficient cells by qRT-PCR. The partial reduction of G6PD deficiency-derived IL-8 due to GPX and NF-κB blockers indicated that G6PD deficiency up-regulates pro-inflammatory cytokine IL-8 through oxidative stress and NF-κB pathway. G6PD deficiency predisposes cells to enhanced production of pro-inflammatory cytokine IL-8. Mechanistically, G6PD deficiency up-regulates IL-8 through oxidative stress and NF-κB pathway. The palmitate-induced inflammation in G6PD-deficient HepG2 cells could serve as an in vitro model to study the role of altered redox homeostasis in chronic hepatic inflammation.
    Journal of Inflammation 04/2015; 12(1). DOI:10.1186/s12950-015-0078-z · 2.02 Impact Factor
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    ABSTRACT: Identification of novel biomarkers is needed to improve the diagnosis and prognosis of heart failure (HF). Metabolic disturbance is remarkable in patients with HF. This study sought to assess the diagnostic and prognostic values of metabolomics in HF. Mass spectrometry-based profiling of plasma metabolites was performed in 515 participants; the discovery phase study enrolled 51 normal control subjects and 183 HF patients, and the validation study enrolled 63 control subjects and 218 patients with stage C HF. Another independent group of 32 patients with stage C HF who recovered to New York Heart Association functional class I at 6 and 12 months was profiled as the "recovery" group. A panel of metabolites, including histidine, phenylalanine, spermidine, and phosphatidylcholine C34:4, has a diagnostic value similar to B-type natriuretic peptide (BNP). In the recovery group, the values of this panel significantly improved at 6 and 12 months. To evaluate the prognostic values, events were defined as the combined endpoints of death or HF-related re-hospitalization. A metabolite panel, which consisted of the asymmetric methylarginine/arginine ratio, butyrylcarnitine, spermidine, and the total amount of essential amino acids, provided significant prognostic values (p < 0.0001) independent of BNP and traditional risk factors. The prognostic value of the metabolite panel was better than that of BNP (area under the curve of 0.85 vs. 0.74 for BNP) and Kaplan-Meier curves (log rank: 17.5 vs. 9.95). These findings were corroborated in the validation study. Metabolomics demonstrate powerful diagnostic value in estimating HF-related metabolic disturbance. The profile of metabolites provides better prognostic value versus conventional biomarkers. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
    Journal of the American College of Cardiology 04/2015; 65(15):1509-20. DOI:10.1016/j.jacc.2015.02.018 · 16.50 Impact Factor
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    ABSTRACT: Atrial fibrillation (AF) is associated with structural remodeling in atrial myocytes. Emerging evidence suggests that statin has a protective effect on AF through cholesterol-independent mechanisms. The aim of this study is to investigate whether heme oxygenase-1 (HO-1), a potent antioxidant system, mediates the suppressive effect of statin on atrial tachycardia-induced structural remodeling. Treatment of cultured atrium-derived myocytes (HL-1 cell line) with rosuvastatin enhanced HO-1 expression/activity and attenuated tachypacing-induced oxidative stress and myofibril degradation. Heme oxygenase-1 inhibitors and small-interfering RNA for HO-1 blocked the inhibitory effect of rosuvastatin on tachypacing-stimulated changes, suggesting the crucial role of HO-1 in mediating the effect of rosuvastatin. Time-dependent experiments and loss-of-function study demonstrated that Akt/Nrf2 pathways lay to the up-stream of HO-1 in this signaling cascade. Furthermore, the involvement of Akt/Nrf2/HO-1 pathway in the antioxidant effect of rosuvastatin was documented in an ex vivo tachypacing model. The suppressive effect of statin on atrial tachypacing-induced cellular remodeling is mediated via the activation of Akt/Nrf2/HO-1 signaling, which provides a possible explanation for the protective effect of statin on AF. Copyright © 2015. Published by Elsevier Ltd.
    Journal of Molecular and Cellular Cardiology 03/2015; 82. DOI:10.1016/j.yjmcc.2015.03.004 · 4.66 Impact Factor
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    ABSTRACT: Aims: Glucose 6-phosphate dehydrogenase (G6PD) is essential for maintenance of nicotinamide dinucleotide hydrogen phosphate (NADPH) levels and redox homeostasis. A number of drugs, such as antimalarial drugs, act to induce reactive oxygen species and hemolytic crisis in G6PD-deficient patients. We used diamide (DIA) to mimic drug-induced oxidative stress and studied how these drugs affect cellular metabolism using a metabolomic approach. Results: There are a few differences in metabolome between red blood cells (RBCs) from normal and G6PD-deficient individuals. DIA causes modest changes in normal RBC metabolism. In contrast, there are significant changes in various biochemical pathways, namely glutathione (GSH) metabolism, purine metabolism, and glycolysis, in G6PD-deficient cells. GSH depletion is concomitant with a shift in energy metabolism. Adenosine monophosphate (AMP) and adenosine diphosphate (ADP) accumulation activates AMP protein kinase (AMPK) and increases entry of glucose into glycolysis. However, inhibition of pyruvate kinase (PK) reduces the efficacy of energy production. Metabolic changes and protein oxidation occurs to a greater extent in G6PD-deficient RBCs than in normal cells, leading to severe irreversible loss of deformability of the former. Innovation and conclusion: Normal and G6PD-deficient RBCs differ in their responses to oxidants. Normal cells have adequate NADPH regeneration for maintenance of GSH pool. In contrast, G6PD-deficient cells are unable to regenerate enough NADPH under a stressful situation, and switch to biosynthetic pathway for GSH supply. Rapid GSH exhaustion causes energy crisis and futile AMPK activation. Our findings suggest that drug-induced oxidative stress differentially affects metabolism and metabolite signaling in normal and G6PD-deficient cells. It also provides an insight into the pathophysiology of acute hemolytic anemia in G6PD-deficient patients.
    Antioxidants and Redox Signaling 01/2015; 22(9). DOI:10.1089/ars.2014.6142 · 7.41 Impact Factor
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    ABSTRACT: Metabolite identification remains a bottleneck in mass spectrometry (MS)-based metabolomics. Currently, this process relies heavily on tandem mass spectrometry (MS/MS) spectra generated separately for peaks of interest identified from previous MS runs. Such a delayed and labor-intensive procedure creates a barrier to automation. Further, information embedded in MS data has not been used to its full extent for metabolite identification. Multimers, adducts, multiply charged ions, and fragments of given metabolites occupy a substantial proportion (40-80%) of the peaks of a quantitation result. However, extensive information on these derivatives, especially fragments, may facilitate metabolite identification. We propose a procedure with automation capability to group and annotate peaks associated with the same metabolite in the quantitation results of opposite modes, and to integrate this information for metabolite identification. In addition to the conventional mass and isotope ratio matches, we would match annotated fragments with low-energy MS/MS spectra in public databases. For identification of metabolites without accessible MS/MS spectra, we have developed characteristic fragment and common substructure matches. The accuracy and effectiveness of the procedure were evaluated using one public and two in-house liquid chromatography-mass spectrometry (LC-MS) datasets. The procedure accurately identified 89% of 28 standard metabolites with derivative ions in the datasets. With respect to effectiveness, the procedure confidently identified the correct chemical formula of at least 42% of metabolites with derivative ions via MS/MS spectrum, characteristic fragment, and common substructure matches. The confidence level was determined according to the fulfilled identification criteria of various matches and relative retention time.
    Analytical Chemistry 12/2014; 87(4). DOI:10.1021/ac503325c · 5.64 Impact Factor
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    Mei-Ling Cheng · Shiue-Fen Weng · Chih-Hao Kuo · Hung-Yao Ho
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    ABSTRACT: Redox homeostasis is an important host factor determining the outcome of infectious disease. Enterovirus 71 (EV71) infection has become an important endemic disease in Southeast Asia and China. We have previously shown that oxidative stress promotes viral replication, and progeny virus induces oxidative stress in host cells. The detailed mechanism for reactive oxygen species (ROS) generation in infected cells remains elusive. In the current study, we demonstrate that mitochondria were a major ROS source in EV71-infected cells. Mitochondria in productively infected cells underwent morphologic changes and exhibited functional anomalies, such as a decrease in mitochondrial electrochemical potential ΔΨm and an increase in oligomycin-insensitive oxygen consumption. Respiratory control ratio of mitochondria from infected cells was significantly lower than that of normal cells. The total adenine nucleotide pool and ATP content of EV71-infected cells significantly diminished. However, there appeared to be a compensatory increase in mitochondrial mass. Treatment with mito-TEMPO reduced eIF2α phosphorylation and viral replication, suggesting that mitochondrial ROS act to promote viral replication. It is plausible that EV71 infection induces mitochondrial ROS generation, which is essential to viral replication, at the sacrifice of efficient energy production, and that infected cells up-regulate biogenesis of mitochondria to compensate for their functional defect.
    PLoS ONE 11/2014; 9(11):e113234. DOI:10.1371/journal.pone.0113234 · 3.23 Impact Factor
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    ABSTRACT: Background The hepatitis C virus (HCV) genotype-specific impacts on the host metabolic alterations remained inconclusive. Methods A prospective study including 229 (118 genotype 1 (G1) and 111 G2) consecutive chronic HCV patients who had completed a course of anti-HCV treatment and underwent pre- and 24 weeks post-treatment surveys of metabolic profiles was conducted. Patients were stratified according to the therapeutic response, viral genotype and baseline insulin resistance (IR: homeostasis model assessments of IR (HOMA-IR) ≥2.5). Paired t-tests were used to compare the pre- and post-treatment variables. Results Significant post-therapeutic increases in cholesterol, triglyceride, HDL, LDL, apolipoprotein A1 and apolipoprotein B were observed in patients with sustained virological response (SVR) but not in those without. Among those with SVR, post-therapeutic increases in HDL (p<0.001) and apolipoprotein A1 (p = 0.012) were only found in G2, whereas increased triglyceride/HDL (p = 0.01) ratios were only found in G1 patients. When stratified by baseline IR among those with SVR, a significant increase in post-treatment HDL (p = 0.019) and apolipoprotein A1 (p = 0.012) but a decrease in HOMA-IR (p = 0.04), C-peptide (p = 0.019) and hemoglobin A1c (p = 0.047) were found in patients with baseline IR; a significant increase in HOMA-IR (p = 0.002) was found in patients without baseline IR. The latter change was observed only in G1 (p = 0.01) but not G2 patients. Although the pre-treatment metabolic profiles of G1 and G2 patients were indifferent, G1 had higher post-treatment triglyceride/HDL ratios (p = 0.041) and triglyceride (p = 0.044) levels than G2 patients. Conclusions G2 benefit more than G1 patients from viral clearance in metabolic alterations, particularly in those without baseline IR.
    PLoS ONE 08/2014; 9(8):e104783. DOI:10.1371/journal.pone.0104783 · 3.23 Impact Factor
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    ABSTRACT: Background Methionine, an essential amino acid, is required for protein synthesis and normal cell metabolism. The transmethylation pathway and methionine salvage pathway (MTA cycle) are two major pathways regulating methionine metabolism. Recently, methionine has been reported to play a key role in Drosophila fecundityResultsHere, we revealed that the MTA cycle plays a crucial role in Drosophila fecundity using the mutant of aci-reductone dioxygenase 1 (DADI1), an enzyme in the MTA cycle. In dietary restriction condition, the egg production of adi1 mutant flies was reduced compared to that of control flies. This fecundity defect in mutant flies was rescued by reintroduction of Dadi1 gene. Moreover, a functional homolog of human ADI1 also recovered the reproduction defect, in which the enzymatic activity of human ADI1 is required for normal fecundity. Importantly, methionine supply rescued the fecundity defect in Dadi1 mutant flies. The detailed analysis of Dadi1 mutant ovaries revealed a dramatic change in the levels of methionine metabolism. In addition, we found that three compounds namely, methionine, SAM and Methionine sulfoxide, respectively, may be required for normal fecundityConclusions In summary, these results suggest that ADI1, an MTA cycle enzyme, affects fly fecundity through the regulation of methionine metabolism.
    Journal of Biomedical Science 07/2014; 21(1):64. DOI:10.1186/s12929-014-0064-4 · 2.76 Impact Factor
  • Hung-Yao Ho · Mei-Ling Cheng · Daniel Tsun-Yee Chiu
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    ABSTRACT: Abstract Glucose-6-phosphate dehydrogenase (G6PD) is critical to the maintenance of NADPH pool and redox homeostasis. Coventionally, G6PD deficiency has been associated with hemolytic disorders. Most biochemical variants were identified and characterized at molecular level. Recently, a number of studies have shone light on the roles of G6PD in aspects of physiology other than erythrocytic pathophysiology. G6PD deficiency alters the redox homeostasis, and affects dysfunctional cell growth and signaling, anomalous embryonic development, and altered susceptibility to infection. The present article gives a brief review of basic science and clinical findings about G6PD, and covers the latest development in the field. Moreover, how G6PD status alters the susceptibility of the affected individuals to certain degenerative diseases is also discussed.
    Free Radical Research 04/2014; 48(9). DOI:10.3109/10715762.2014.913788 · 2.98 Impact Factor
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    ABSTRACT: Spinocerebellar ataxia (SCAs) types 1, 2, 3, 6, 7, 17, and dentatorubropallidoluy-sianatrophy (DRPLA) as well as Huntington's disease (HD) are a group of neurodegenerative disorders caused by a CAG triplet repeat expansion encoding a long polyglutamine (polyQ) tract in the respective mutant proteins. The cytoplasmic and nuclear aggregate formation, pathological hallmark of polyQ diseases, is likely the initial process to trigger the subsequent pathological events. Compromised oxidative stress defense capacity and mitochondrial dysfunction have emerged as contributing factors to the pathogenesis of polyQ diseases. The roots of licorice (Glycyrrhiza) species have long been used as an herbal medicine. In the present study, we demonstrated the aggregate-inhibitory effect of Glycyrrhiza inflata (G. inflata) herb extract and its constituents licochalcone A and ammonium glycyrrhizinate (AMGZ) in both 293 and SH-SY5Y ATXN3/Q75 cells, SCA3 cell models. The reporter assay showed that G. inflata herb extract, licochalcone A and AMGZ could enhance the promoter activity of peroxisome proliferator-activated receptor gamma, coactivator 1 alpha (PPARGC1A), a known regulator of mitochondrial biogenesis and anti-oxidative response genes. G. inflata extract, licochalcone A and AMGZ up-regulated PPARGC1A expression and its downstream target genes, SOD2 and CYCS, in 293 ATXN3/Q75 cell model. The expression of nuclear factor erythroid 2-related factor 2 (NFE2L2), the principal transcription factor that binds to anti-oxidant responsive elements (ARE) to promote ARE-dependent gene expression when the cells respond to oxidative stress, and its downstream genes, HMOX1, NQO1, GCLC and GSTP1 were also increased by G. inflata herb extract, licochalcone A and AMGZ. Knock down of PPARGC1A increased aggregates in ATXN3/Q75 cells and also attenuated the aggregate-inhibiting effect of the tested compounds. G. inflata extract and its constituents significantly elevated GSH/GSSG ratio and reduced reactive oxidative species in ATXN3/Q75 cells. The study results suggest that the tested agents activate PPARGC1A activity and NFE2L2-ARE signaling to increase mitochondrial biogenesis, decrease oxidative stress, and reduce aggregate formation in SCA3 cellular models.
    Free Radical Biology and Medicine 03/2014; 71. DOI:10.1016/j.freeradbiomed.2014.03.023 · 5.74 Impact Factor
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    ABSTRACT: Autophagy and endoplasmic reticulum (ER) stress response is important for cancer cells to maintain malignancy and resistance to therapy. trans-Resveratrol (RSV), a non-flavonoid agent, has been shown to induce apoptosis in human nasopharyngeal carcinoma (NPC) cells. In this study, the involvements of tumor-specific ER stress and autophagy in the RSV-mediated apoptosis were investigated. In addition to traditional autophagosomes, the images of transmission electron microscopy (TEM) indicated that RSV markedly induced larger, crescent-shaped vacuoles with single-layered membranes whose the expanded cisternae contains multi-lamellar membrane structures. Prolonged exposure to RSV induced a massive accumulation of ER expansion. Using an EGFP-LC3B transfection and confocal laser microscopy approach, we found RSV-induced EGFP-LC3 puncta co-localized with ER-tracker red dye, implicating the involvement of LC3II in ER expansion. The proapoptotic effect of RSV was enhanced after suppression of autophagy by ATG7 siRNA or blocking the autophagic flux by bafilomycin A1, but that was not changed after targeted silence of IRE1 or CHOP by siRNA. Using caspase inhibitors, we demonstrated the upregulation of caspase-12 (casp12) and the activation of casp4 were associated with the proapoptotic induction of RSV through the caspase-9/caspase-3 pathway. Intriguingly, siRNA knockdown of casp12, but not caspase-4, decreased the susceptibility of the NPC cells to RSV-mediated apoptosis. Further, we showed that RSV dose-dependently increased the ceramide accumulation as assessed by LC-MS/MS system. Using serine palmitoyltransferase (SPT, a key enzyme of de novo ceramide biosynthesis) inhibitors (L-cycloserine and myriocin), we found the increased ceramide accumulation was strongly correlated with the proapoptotic potential of RSV. This study revealed the ER expansion and upregulation of ER casp12 together may indicate profound biological effects of RSV and contributed to NPC cell death. Targeting the different status of ER stress may provide a possible strategy for cancer treatments.
    Apoptosis 11/2013; 19(3). DOI:10.1007/s10495-013-0945-0 · 3.69 Impact Factor
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    ABSTRACT: Glucose-6-phosphate dehydrogenase (G6PD) is pivotal to reduced nicotinamide adenine dinucleotide phosphate (NADPH) production and cellular redox balance. Cells with G6PD deficiency are susceptible to oxidant-induced death at high oxidative stress. However, it remains unclear what precise biological processes are affected by G6PD deficiency due to altered cellular redox homeostasis, particularly at low oxidative stress. To further explore the biological role of G6PD, we generated G6PD-knockdown cell clones using lung cancer line A549. We identified proteins differentially expressed in the knockdown clones without the addition of exogenous oxidant by means of isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with multidimensional liquid chromatography–mass spectrometry (LC–MS/MS). We validated a panel of proteins that showed altered expression in G6PD-knockdown clones and were involved in metabolism of xenobiotic and glutathione (GSH) as well as energy metabolism. To determine the physiological relevancy of our findings, we investigated the functional consequence of G6PD depletion in cells treated with a prevalent xenobiotic, aflatoxin B1 (AFB1). We found a protective role of G6PD in AFB1-induced cytotoxicity, possibly via providing NADPH for NADPH oxidase to induce epoxide hydrolase 1 (EPHX1), a xenobiotic-metabolizing enzyme. Collectively, our findings reveal for the first time a proteome-wide dysregulation by G6PD depletion under the condition without exogenous oxidant challenge, and we suggest a novel association of G6PD activity with AFB1-related xenobiotic metabolism.
    Journal of Proteome Research 06/2013; 12(7):3434–3448. DOI:10.1021/pr4002959 · 4.25 Impact Factor
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    ABSTRACT: Abstract In response to infection, neutrophils employ various strategies to defend against the invading microbes. One of such defense mechanism is the formation of neutrophil extracellular traps (NETs). Recent studies suggest that reactive oxygen species is a signal critical to NET formation. This prompts us to examine whether neutrophils from individuals with glucose-6-phosphate dehydrogenase (G6PD) Taiwan-Hakka variant, which are prone to oxidative stress generation, have altered ability to form NET. We adopted an image-based method to study the NET formation potential in neutrophils from G6PD-deficient patients. Neutrophils from either normal or G6PD-deficient individuals underwent NETosis in response to phorbol 12-myristate 13-acetate (PMA). The extent of NETosis in the former did not significantly differ from that of the latter. Diphenyleneiodonium sulfate (DPI) and 3-methyladenine (MA) inhibited PMA-stimulated NET formation in these cells, suggesting the involvement of NADPH oxidase and autophagy in the process. Glucose oxidase (GO) and xanthine oxidase/xanthine (XO/X) could induce a similar extent of NET formation in normal and G6PD-deficient neutrophils. GO- or XO-induced NETosis was not inhibitable by MA, implying that reactive oxygen species (ROS) can act as an independent signal for activation of NETosis. Mechanistically, enhanced superoxide production in neutrophils was associated with increases in levels of NAD(+) and NADP(+), as well as activation of NAD(+) kinase. Taken together, these findings suggest that G6PD-deficient neutrophils are as equally efficient as normal cells in NET formation, and their deficiency in G6PD-associated NADPH regeneration capacity is largely compensated for by nicotinamide nucleotide biosynthesis.
    Free Radical Research 06/2013; 47(9). DOI:10.3109/10715762.2013.816420 · 2.98 Impact Factor
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    ABSTRACT: OBJECTIVE Metabolic syndrome is a multiplex disorder and puts patients on the road to type 2 diabetes and atherosclerotic cardiovascular diseases. However, a surrogate biomarker in plasma or urine in fully reflecting features of metabolic syndrome has not been explored.RESEARCH DESIGN AND METHODS Urine metabolomics has potential utility in metabolic profiling because urine metabolites analysis reflects global outflux of metabolic change. Accordingly, we collected data on subjects (n = 99) with overweight, dyslipidemia, hypertension or impaired glucose tolerance and took a metabolomics approach to analyze the metabolites of urine revealed in metabolic syndrome by high-performance liquid chromatography-time-of-flight mass spectrometry and elicit potential biomarkers to picture metabolic syndrome.RESULTSOur results revealed that the urine nicotinuric acid value of subjects with diabetes (HbA(1c) ≥6.5% or those receiving diabetes medications) (n = 25) was higher than subjects without diabetes (n = 37) (221 ± 31 vs. 152 ± 13 × 10(3) mAU, P = 0.0268). Moreover, urinary nicotinuric acid level was positively correlated with body mass index, blood pressure, total cholesterol, low-density lipoprotein cholesterol, triacylglycerol and high sensitivity C-reactive protein, but negatively correlated with high-density lipoprotein cholesterol.CONCLUSIONS This is the first study, to our knowledge, to propose that nicotinuric acid represents an important pathogenic mechanism in process from metabolic syndrome to diabetes and atherosclerotic cardiovascular disease.
    Diabetes care 12/2012; 36(6). DOI:10.2337/dc12-1067 · 8.42 Impact Factor
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    ABSTRACT: G6PD is crucial to NADPH generation and redox homeostasis. We have recently shown that G6PD deficiency predisposes cells to oxidant-induced cell death, and it is associated with the impairment of GSH regeneration. It remains unclear what other metabolic pathways are affected by G6PD deficiency, and whether the altered metabolism disturbs cellular redox homeostasis and underlies the increased susceptibility to oxidants. In the study, we examined the effect of diamide on global metabolite profiles of SK-Hep1-derived SK-i-Gi and SK-i-Sc cells, which could inducibly express shRNAs against G6PD (Gi) and control shRNA (Sc), respectively. There was no significant difference in their metabolite profiles under uninduced condition. Doxycycline (Dox) addition resulted in over 70% decrease in G6PD activity in SK-i-Gi cells. It was accompanied by relatively minor changes in the metabolome of SK-i-Gi cells. Upon further diamide treatment, the metabolite profiles of both SK-i-Gi and SK-i-Sc cells changed in a time-dependent manner. A number of metabolic pathways, including those involved in energy metabolism and metabolism of amino acid and glutathione, were affected. However, the changes in metabolite profile of Dox-treated SK-i-Gi cells were distinct from those of control cells (i.e. Dox-treated SK-i-Sc, SK-i-Gi, and SK-i-Sc cells). Cellular glutathione was depleted, while its disulfide form increased significantly in diamide, Dox-treated SK-i-Gi cells. Metabolites related to energy metabolism, such as AMP, ADP and acetylcarnitine, increased to a greater extent in these cells than in diamide-treated control cells. In contrast, nicotinamide adenine dinucleotide (NAD) and glutathione dropped to a lower level in SK-i-Gi cells than in control cells. The NAD depletion in SK-i-Gi cells was accompanied by a significant increase in NAD kinase activity. Targeted analyses revealed that NADP and NADPH increased significantly in diamide, Dox-treated SK-i-Gi cells as compared with similarly treated control cells. Our results suggest that diamide induces oxidation and depletion of glutathione in SK-i-Gi cells under the condition of G6PD shRNA induction, and subsequently induces conversion of NAD to NADP through enhanced NAD kinase activity. This may represent a compensatory mechanism to restore cellular NADPH reserve in G6PD-deficient cells. It is accompanied by alteration in pathways of cellular energy metabolism, such as glycolysis and β-oxidation.
    Free Radical Biology and Medicine 11/2012; 54. DOI:10.1016/j.freeradbiomed.2012.10.557 · 5.74 Impact Factor
  • Free Radical Biology and Medicine 11/2012; 53:S37. DOI:10.1016/j.freeradbiomed.2012.10.096 · 5.74 Impact Factor
  • Yu-Ting Lin · Mei-Ling Cheng · Daniel Tsun-Yee Chiu · Hung-Yao Ho
    Free Radical Biology and Medicine 11/2012; 53:S44. DOI:10.1016/j.freeradbiomed.2012.10.114 · 5.74 Impact Factor
  • Jui-Fen Lin · Mei-Ling Cheng · Daniel Tsun-Yee Chiu
    Free Radical Biology and Medicine 11/2012; 53:S158. DOI:10.1016/j.freeradbiomed.2012.10.431 · 5.74 Impact Factor
  • Hsiang-Yu Tang · Mei-Ling Cheng · Daniel Tsun-Yee Chiu
    Free Radical Biology and Medicine 11/2012; 53:S146. DOI:10.1016/j.freeradbiomed.2012.10.394 · 5.74 Impact Factor

Publication Stats

702 Citations
261.13 Total Impact Points


  • 2000–2015
    • Chang Gung University
      • • Department of Biomedical Sciences
      • • Department of Medical Biotechnology and Laboratory Science
      • • College of Medicine
      Hsin-chu-hsien, Taiwan, Taiwan
  • 2005–2014
    • Chang Gung Memorial Hospital
      • Department of Laboratory Medicine
      T’ai-pei, Taipei, Taiwan
  • 1999
    • National Taiwan University
      • College of Medicine
      T’ai-pei, Taipei, Taiwan