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Zhang YN, Wu WQ, Ding ZH, Huang TM, Luo YM, Chen S. [Application of computational fluid dynamics in the evaluation of left ventricular function in cardiomyopathies and coronary disease]. Zhonghua Wai Ke Za Zhi 2024; 62:467-472. [PMID: 38548618 DOI: 10.3760/cma.j.cn112139-20231020-00183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
Computational fluid dynamics (CFD) is an emerging technology applied in the field of cardiovascular medicine, which can obtain hemodynamic data by simulating the blood flow in the patient's heart for cardiac function assessment and disease diagnosis. Left ventricular function plays a key role in the occurrence and development of cardiomyopathies and coronary disease. CFD can reconstruct the left ventricular anatomic structures of patients to clarify pathophysiologic mechanisms and analyze hemodynamic parameters to evaluate left ventricular function, verify surgical efficacy, and guide surgical strategy, which has a positive effect on achieving early diagnosis and reducing mortality from cardiomyopathies and coronary disease. At present, there are still technical limitations in the large-scale clinical application of CFD, and various solutions are being developed and tested, and further improvement and refinement are needed.
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Affiliation(s)
- Y N Zhang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - W Q Wu
- Department of Ultrasound Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Z H Ding
- Department of Technology, Boea Wisdom (Hangzhou) Network Technology Co., Ltd, Hangzhou 310000, China
| | - T M Huang
- Department of Technology, Boea Wisdom (Hangzhou) Network Technology Co., Ltd, Hangzhou 310000, China
| | - Y M Luo
- Department of Mechanical Engineering, the University of Iowa, Iowa City 52242, United States
| | - S Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Lin YF, Huang TM, Chung WH, Ueng YL. Forecasting Fluctuations in the Financial Index Using a Recurrent Neural Network Based on Price Features. IEEE Trans Emerg Top Comput Intell 2021. [DOI: 10.1109/tetci.2020.2971218] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Hsu CT, Tsai JH, Huang TM, Hsin JC, Chen JZ, Lee BS, Yang TC. Atmospheric pressure plasma jet treatment enhances the effect of Alloy Primer on the bond strength between polymethyl methacrylate and stainless steels: application for retention of magnetic attachment to resin denture base. Colloids Surf B Biointerfaces 2020; 197:111440. [PMID: 33130522 DOI: 10.1016/j.colsurfb.2020.111440] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 10/15/2020] [Accepted: 10/22/2020] [Indexed: 02/07/2023]
Abstract
Magnetic attachment system is used to embed in polymethyl methacrylate (PMMA) resin denture base to improve denture stability. However, dislodgement of magnetic attachments from denture base is a major clinical problem. This study is to evaluate the bond strength between PMMA and stainless steel using metal primer and atmospheric pressure plasma jet (APPJ) treatment. Stainless steel discs were treated with Single Bond Universal Adhesive; Palfique Universal Bond; Alloy Primer; heat treatment with Alloy Primer; and 10-s, 20-s, and 30-s APPJ treatment with Alloy Primer. The shear bond strength between PMMA and surface-treated stainless steel was measured using universal testing machine. The effects of N2 flow rate (60, 50, 40, 30 SLM), thermal cycling, and air quenching on shear bond strength were also investigated. The surface of each disc was examined using X-ray photoelectron spectroscopy and a goniometer. Finally, the temperature of plasma with various N2 flow rates was measured and the optical emission spectra of the plasma were measured using spectrometer. Alloy Primer produced the highest bond strength. APPJ treatment was effective at enhancing bond strength by cleaning the surface of contaminants. Moreover, APPJ treatment with air quenching increased surface O2-/OH- and Fe2O3/FeOOH ratios, reducing the negative influence of thermal cycling on bond strength. Alloy Primer with 20 s of APPJ treatment with a 50-SLM N2 flow rate and air quenching was the most effective at increasing bond strength.
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Affiliation(s)
- Chen-Ting Hsu
- Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei 106, Taiwan
| | - Jui-Hsuan Tsai
- Graduate Institute of Applied Mechanics and Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei City, 10617, Taiwan
| | - Tzu-Ming Huang
- Graduate Institute of Applied Mechanics and Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei City, 10617, Taiwan
| | - Jui-Chen Hsin
- Graduate Institute of Applied Mechanics and Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei City, 10617, Taiwan
| | - Jian-Zhang Chen
- Graduate Institute of Applied Mechanics and Advanced Research Center for Green Materials Science and Technology, National Taiwan University, Taipei City, 10617, Taiwan
| | - Bor-Shiunn Lee
- Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University and National Taiwan University Hospital, Taipei 106, Taiwan.
| | - Tsung-Chieh Yang
- School of Dentistry, National Taiwan University and National Taiwan University Hospital, No.1, Chang-Te St., 10048, Taipei 106, Taiwan.
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4
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Lee CC, Huang TM, Cheng IC, Chen JZ. Investigation of ultrashort (< 1 min) calcination processes for conversion of Pt–SnOx from mixture of chloroplatinic acid and tin(II) chloride. SN Appl Sci 2019. [DOI: 10.1007/s42452-019-0933-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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5
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Hsu RH, Chien YH, Hwu WL, Chang IF, Ho HC, Chou SP, Huang TM, Lee NC. Genotypic and phenotypic correlations of biotinidase deficiency in the Chinese population. Orphanet J Rare Dis 2019; 14:6. [PMID: 30616616 PMCID: PMC6323711 DOI: 10.1186/s13023-018-0992-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/28/2018] [Indexed: 12/29/2022] Open
Abstract
Biotinidase deficiency is an autosomal recessive disorder that affects the endogenous recycling and release of biotin from dietary protein. This disease was thought to be rare in East Asia. In this report, we delineate the phenotype of biotinidase deficiency in our cohort. The genotypes and phenotypes of patients diagnosed with biotinidase deficiency from a medical center were reviewed. The clinical manifestations, laboratory findings, and molecular test results were retrospectively analyzed. A total of 6 patients were evaluated. Three patients (50%) were diagnosed because of a clinical illness, and the other three (50%) were identified by newborn screening. In all patients, the molecular results confirmed the BTD mutation. The three patients with clinical manifestations had an onset of seizure at the age of 2 to 3 months. Two patients had respiratory problems (one with apnea under bilevel positive airway pressure (BiPAP) therapy at night, and the other with laryngomalacia). Hearing loss and eye problems were found in one patient. Interestingly, cutaneous manifestations including skin eczema, alopecia, and recurrent fungal infection were less commonly seen compared to cases in the literature. None of the patients identified by the newborn screening program developed symptoms. Our findings highlight differences in the genotype and phenotype compared with those in Western countries. Patients with biotinidase deficiency benefit from newborn screening programs for early detection and management.
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Affiliation(s)
- Rai-Hseng Hsu
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, Taipei Medical University Hospital, No. 252, Wuxing St, Xinyi Dist., Taipei, 11031 Taiwan
| | - Yin-Hsiu Chien
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Wuh-Liang Hwu
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - I-Fan Chang
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Hui-Chen Ho
- Taipei Institute of Pathology, No.146, Sec.3, Chongqing N. Rd., Datong Dist., Taipei, 10374 Taiwan
| | - Shi-Ping Chou
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Tzu-Ming Huang
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Ni-Chung Lee
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
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Wells RP, Ghiorso W, Staples J, Huang TM, Sannibale F, Kramasz TD. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source. Rev Sci Instrum 2016; 87:023302. [PMID: 26931840 DOI: 10.1063/1.4941836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 02/01/2016] [Indexed: 06/05/2023]
Abstract
A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.
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Affiliation(s)
- R P Wells
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - W Ghiorso
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J Staples
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T M Huang
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - F Sannibale
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T D Kramasz
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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7
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Huang TM. Key factors of the successful elevation of service quality by the service industry. Journal of Information and Optimization Sciences 2013. [DOI: 10.1080/02522667.2013.777177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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8
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Huang TM, Wu VC. Extracorporeal membrane oxygenation in H1N1 pandemic: a double edged sword. Minerva Anestesiol 2010; 76:989-991. [PMID: 21178910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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9
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Huang TM. The effects of the top management team on organizational performance. Journal of Statistics and Management Systems 2010. [DOI: 10.1080/09720510.2010.10701502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Huang TM, Lin TL, Wu CC. Antimicrobial susceptibility and resistance of chicken Escherichia coli, Salmonella spp., and Pasteurella multocida isolates. Avian Dis 2009; 53:89-93. [PMID: 19432009 DOI: 10.1637/8268-021608-reg.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Escherichia coli, Salmonella species, and Pasteurella multocida are the major bacterial pathogens isolated from poultry. Difference in susceptibility to antibiotics by microorganisms has become a major factor in drug choice and success of treatment. Great concerns have been raised regarding emerging antimicrobial resistance among bacteria that may result in unpredictable antimicrobial susceptibility and failure of therapy. The primary objective of the present study was to determine the levels of antimicrobial susceptibility/resistance of E. coli, Salmonella species, and P. multocida isolated from diseased chickens. A total of 445 E. coli isolates, 387 Salmonella spp. isolates, and 80 P. multocida isolates from diseased chickens during the period ranging from 2001 to 2003 were obtained. Minimal inhibitory concentrations of 14 antimicrobial agents against each bacterial isolate were determined using a microbroth dilution assay described by the Clinical Laboratory Standards Institute. Resistance of E. coli isolates measured as follows: 98.20% were resistant to tilmicosin, 79.33% to tetracycline, 51.46% to spectinomycin, 44.04% to gentamicin, and 40% to ampicillin. Resistance to tetracycline was found in 72.61% of Salmonella spp. isolated, followed by resistance to spectinomycin (68.48%), ampicillin (63.57%), gentamicin (63.31%), and ticarcillin (61.76%). The resistance rate of P. multocida isolates to all antimicrobials tested was less than 5%, except for tetracycline (6.25%). In summary, E. coli and Salmonella isolates were sensitive to ceftiofur and fluoroquinolones but were resistant to other antimicrobials tested, while P. multocida isolates remained sensitive to all the antimicrobial agents tested in a 3-yr analysis.
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Affiliation(s)
- Tzu-Ming Huang
- Department of Comparative Pathobiology, Purdue University, West Lafayette, IN 47907-2065, USA
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11
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Huang TM, Lin TL, Wu CC. Antimicrobial Susceptibility and Resistance of ChickenEscherichia coli,SalmonellaSPP., andPasteurella multocidaIsolates. ACTA ACUST UNITED AC 2009. [DOI: 10.1637/8622.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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12
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Huang TM, Chang YF, Chang CF. Detection of mutations in the gyrA gene and class I integron from quinolone-resistant Salmonella enterica serovar Choleraesuis isolates in Taiwan. Vet Microbiol 2004; 100:247-54. [PMID: 15145503 DOI: 10.1016/j.vetmic.2004.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2003] [Revised: 03/02/2004] [Accepted: 03/04/2004] [Indexed: 11/21/2022]
Abstract
The quinolone resistance-determining regions (QRDRs) of the gyrA gene of quinolone-resistant Salmonella enterica serovar Choleraesuis isolates were sequenced. Four types of point mutation, Ser-83-to-Phe (TCC --> TTc), Ser-83-to-Tyr (TCC --> TAC), Asp-87-to-Gly (GAC --> GGC), and Asp-87-to-Asn (GAC --> AAC), were found. PCR-RFLP and MAS-touch down PCR were performed on fifty swine clinical isolates of S. enterica serovar Choleraesuis (NalR) collected during 1997-2002. The analysis indicated seven isolates with point mutations in codon 83, 13 with point mutations in codon 87, and 30 with double mutations in both codons 83 and 87. The MICs of enrofloxacin of the isolates with a single mutation in codon 83 or 87 were <2microg/ml, while the MICs of the isolates with double mutations in both codon 83 and 87 ranged from 2 to 64microg/ml. A class I integron comprised of dhfr, orfF and aad2 was also identified in both human and swine S. enterica serovar Choleraesuis isolates. These results indicate that PCR-RFLP and MAS-touchdown PCR assays can be used for surveillance of gyrA gene mutations, which are important for fluoroquinolone resistance in Salmonella. Isolates with double mutations in gyrA codons 83 and 87 are the major type of quinolone-resistant Salmonella isolated from swine in Taiwan. A surveillance system may be applied to the swine industry to monitor the emergence of fluoroquinolone and/or multi-drug-resistant S. enterica serovar Choleraesuis in Taiwan.
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Affiliation(s)
- Tzu-Ming Huang
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA
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Lee FY, Lien JC, Huang LJ, Huang TM, Tsai SC, Teng CM, Wu CC, Cheng FC, Kuo SC. Synthesis of 1-benzyl-3-(5'-hydroxymethyl-2'-furyl)indazole analogues as novel antiplatelet agents. J Med Chem 2001; 44:3746-9. [PMID: 11606139 DOI: 10.1021/jm010001h] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1-Benzyl-3-(5'-hydroxymethyl-2'-furyl)indazole (28, YC-1) was selected as the lead compound for systemic structural modification. After screening for antiplatelet activity, SARs of YC-1 analogues were established. Among these potent active derivatives, compounds 29, 30, 31, 44, and 45 functioned as potent activators of sGC and inhibitors of PDE5 with potency comparable to that of YC-1. In addition, compound 58 was found to be a selective and potent inhibitor of protease-activated receptor type 4 (PAR4)-dependent platelet activation.
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Affiliation(s)
- F Y Lee
- Graduate Institute of Pharmaceutical Chemistry, China Medical College, Taichung, Taiwan, ROC
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Liou JY, Huang TM, Chang GG. Inhibition of octopus glutathione transferase by Meisenheimer complex analog, S-(2,4,6-trinitrophenyl) glutathione. J Protein Chem 2000; 19:615-20. [PMID: 11233176 DOI: 10.1023/a:1007195130725] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The tight binding of Meisenheimer intermediate with octopus digestive gland glutathione transferase was analyzed with 1,3,5-trinitrobenzene, which forms a trapped Meisenheimer complex with glutathione because there is no leaving group at the ipso carbon. By steady-state enzyme kinetic analysis, an inhibition constant of 1.89 +/- 0.17 microM was found for the transient formed, S-(2,4,6-trinitrophenyl) glutathione. The above inhibition constant is 407-fold smaller than the Km value for the substrate (2,4-dinitrochlorobenzene). Thus, S-(2,4,6-trinitrophenyl) glutathione is considered to be a transition-state analog. The tight binding of this inhibitor to the enzyme provides an explanation for the involvement of the biological binding effect on the rate enhancement in the glutathione transferase-catalyzed SNAr mechanism.
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Affiliation(s)
- J Y Liou
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan
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Chang GG, Huang TM, Hung HC. Reverse micelles as life-mimicking systems. Proc Natl Sci Counc Repub China B 2000; 24:89-100. [PMID: 10943941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
In this review, we attempt to demonstrate that reverse micelles are simple artificial systems that mimic many life systems from cell division to the creation of an enzyme catalytic mechanism. For a membranous enzyme like placental alkaline phosphatase, the kinetic properties observed in reverse micelles might represent those found under physiological conditions. The reverse micellar system, consisting of a positively charged surfactant, mimics a detoxification enzyme glutathione transferase. We propose a novel island-in-oil-lake reverse micellar model for the glutathione transferase that can account for almost all the catalytic properties of this enzyme. Reverse micelles may provide an excellent model system in investigating the reaction mechanism of other detoxification enzymes.
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Affiliation(s)
- G G Chang
- Graduate Institutes of Biochemistry and Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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Pan MH, Huang TM, Lin JK. Biotransformation of curcumin through reduction and glucuronidation in mice. Drug Metab Dispos 1999; 27:486-94. [PMID: 10101144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Curcumin, the yellow pigment in turmeric and curry, has antioxidative and anticarcinogenic activities. In this study, we investigated the pharmacokinetic properties of curcumin in mice. After i.p. administration of curcumin (0.1 g/kg) to mice, about 2.25 microg/ml of curcumin appeared in the plasma in the first 15 min. One hour after administration, the levels of curcumin in the intestines, spleen, liver, and kidneys were 177.04, 26.06, 26.90, and 7.51 microg/g, respectively. Only traces (0.41 microg/g) were observed in the brain at 1 h. To clarify the nature of the metabolites of curcumin, the plasma was analyzed by reversed-phase HPLC, and two putative conjugates were observed. Treatment of the plasma with beta-glucuronidase resulted in a decrease in the concentrations of these two putative conjugates and the concomitant appearance of tetrahydrocurcumin (THC) and curcumin, respectively. To investigate the nature of these glucuronide conjugates in vivo, the plasma was analyzed by electrospray. The chemical structures of these metabolites, determined by mass spectrometry/mass spectrometry analysis, suggested that curcumin was first biotransformed to dihydrocurcumin and THC and that these compounds subsequently were converted to monoglucuronide conjugates. Because THC is one of the major metabolites of curcumin, we studied its stability at different pH values. THC was very stable in 0.1 M phosphate buffers of various pH values. Moreover, THC was more stable than curcumin in 0.1 M phosphate buffer, pH 7.2 (37 degrees C). These results, together with previous findings, suggest that curcumin-glucuronoside, dihydrocurcumin-glucuronoside, THC-glucuronoside, and THC are major metabolites of curcumin in vivo.
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Affiliation(s)
- M H Pan
- Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China
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Abstract
Outbreaks of enterovirus 71 have been reported around the world since 1969. The most recent outbreak occurred in Taiwan during April-July 1998. This hand, foot, and mouth disease epidemic was detected by a sentinel surveillance system in April at the beginning of the outbreak, and the public was alerted.
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Affiliation(s)
- T N Wu
- Disease Surveillance and Quarantine Service, Ministry of Health, Taiwan, Republic of China
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Chen YF, Huang TM, Wang CL, Lee LJ. Compact and Efficient 3.2-W Diode-Pumped Nd:YVO(4)/KTP Green Laser. Appl Opt 1998; 37:5727-5730. [PMID: 18286062 DOI: 10.1364/ao.37.005727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate a simple way to achieve single-frequency operation by using fiber-coupled diode-pumped Nd:YVO(4)/KTP green lasers in a short standing-wave linear cavity. A single-mode output with 3.2-W green power was generated with a 12.6-W pump power corresponding to a conversion efficiency of 25.4%. The single-mode operation was obtained through the combined action of the anisotropic emission cross section of Nd:YVO(4) and the KTP crystal acting as a birefringent filter.
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Abstract
Human placental alkaline phosphatase was embedded in a reverse micellar system prepared by dissolving the surfactant sodium bis(2-ethylhexyl) sulphosuccinate (Aerosol-OT) in 2,2, 4-trimethylpentane. This microemulsion system provides a convenient instrumental tool to study the possible kinetic properties of the membranous enzyme in an immobilized form. The pL (pH/p2H) dependence of hydrolysis of 4-nitrophenyl phosphate has been examined over a pL range of 8.5-12.5 in both aqueous and reverse micellar systems. Profiles of log V versus pL were Ha-bell shaped in the acidic region but reached a plateau in the basic region in which two pKa values of 9.01-9.71 and 9.86-10.48, respectively, were observed in reverse micelles. However, only one pKa value of 9.78-10.27 in aqueous solution was detected. Profiles of log V/K versus pL were bell-shaped in the acidic region. However, they were wave-shaped in the basic region in which a residue of pKa 9.10-9.44 in aqueous solution and 8.07-8.78 in reverse micelles must be dehydronated for the reaction to reach an optimum. The V/K value shifted to a lower value upon dehydronation of a pKa value of 9.80-10.62 in aqueous solution and 11.23-12.17 in reverse micelles. Solvent kinetic isotope effects were measured at three pL values. At pL 9.5, the observed isotope effect was a product of equilibrium isotope effect and a kinetic isotope effect; at pL 10.4, the log V/K value was identical in water and deuterium. The deuterium kinetic isotope effect on V/K was 1.14 in an aqueous solution and 1.16 in reverse micelles. At pL 11.0 at which the log V values reached a plateau in either solvent system, the deuterium kinetic isotope effect on V was 2.08 in an aqueous solution and 0.62 in reverse micelles. Results from a proton inventory experiment suggested that a hydron transfer step is involved in the transition state of the catalytic reaction. The isotopic fractionation factor (pi) for deuterium for the transition state (piT) increased when the pH of the solution was raised. At pL 11.0, the piT was 1.07 in reverse micelles, which corresponds to the inverse-isotope effect of the reaction in this solvent system. Normal viscosity effects on kcat and kcat/Km were observed in aqueous solution, corresponding to a diffusional controlled physical step as the rate-limiting step. We propose that the rate-limiting step of the hydrolytic reaction changes from phosphate releasing in aqueous solution to a covalent phosphorylation or dephosphorylation step in reverse micelles.
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Affiliation(s)
- T M Huang
- Graduate Institutes of Biochemistry and Life Sciences, National Defense Medical Centre, Taipei, Taiwan, Republic of China
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Hung HC, Huang TM, Chang GG. Inhibitory effect of magnesium ion on the human placental alkaline phosphatase-catalyzed reaction in a reverse micellar system. J Protein Chem 1998; 17:99-106. [PMID: 9535271 DOI: 10.1023/a:1022571214482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Human placental alkaline phosphatase is a membrane-anchored protein. Entrapping the enzyme into a reverse micellar vesicle mimics the in vivo conditions and allows examination of the properties of the enzyme. Placental alkaline phosphatase is enzymatically active in Aerosol-OT/isooctane reverse micelles. Substantially different kinetic behavior of the enzyme has been observed in aqueous or reverse micellar systems. In aqueous solution, Mg2+ is a nonessential activator of the enzyme. In the experiments described in the present report Mg2+ was found to be an inhibitor for the enzyme in reverse micelles. This inhibition is presumably due to a time-dependent conformational change of the enzyme molecule, which resulted in a curvature in the recorder tracings of the enzyme assays. The Mg2+-induced conformational change of the enzyme was completely prevented by phosphate and partially reserved by EDTA. High concentrations of Zn2+ also strongly inhibited enzyme activity in both aqueous and reverse micellar solvent systems, presumably by occupying the Mg2+ (M3) site of the enzyme. However, binding of Zn2+ at the M3 site did not cause conformational change of the enzyme and the enzyme assay tracing was linear. The M3 site of the enzyme is proposed to have a modulatory role in vivo using magnesium ion as the modulator.
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Affiliation(s)
- H C Hung
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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21
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Chen YF, Wang SC, Kao CF, Huang TM. Performance of a neodymium yttrium aluminum borate green laser pumped with a fiber-coupled laser diode. Appl Opt 1998; 37:514-517. [PMID: 18268616 DOI: 10.1364/ao.37.000514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Using a space-dependent rate-equation model and considering the effect of pump beam quality, the optimum pump condition for a fiber-coupled diode end-pumped neodymium yttrium aluminum borate laser has been determined. Under optimum pump conditions, greater than 10% optical-to-optical conversion efficiency was obtained when the laser was pumped by a fiber-coupled laser diode with good beam quality. The influence of pump beam quality on the conversion efficiency is also discussed.
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22
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Chen YF, Kao CF, Huang TM. Single-Mode Operation and Frequency Doubling of Fiber-Coupled Diode Butt-Coupling-Pumped Nd:YVO(4) Lasers. Appl Opt 1998; 37:518-521. [PMID: 18268617 DOI: 10.1364/ao.37.000518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We present a simple way to achieve single-frequency operation by using a fiber-coupled diode butt-coupling-pumped Nd:YVO(4) laser in a flat-flat cavity. Single-mode outputs of 620 and 260 mW for fundamental and second-harmonic wavelengths were obtained when the laser was pumped by an 1100-mW fiber-coupled laser diode. Experimental results show that thermal effects provide not only a stable resonator with a good overlap of laser mode and pump size but also enhance single-frequency performance.
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23
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Gu SY, Huang TM, Ruan L, Miao YH, Lu H, Chu CM, Motz M, Wolf H. First EBV vaccine trial in humans using recombinant vaccinia virus expressing the major membrane antigen. Dev Biol Stand 1995; 84:171-177. [PMID: 7796951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In the absence of a truly representative animal model, the question of whether EBV-related diseases can be prevented by a vaccine has been studied for the first time in humans. A live recombinant virus based on the licensed vaccinia strain Tien Tan, expressing under the 11K vaccinia promoter the major EBV membrane antigen BNLF-1 MA (gp 220-340), was constructed and tested in three different human populations: EBV-positive and vaccinia-virus-exposed adults; EBV-positive, non-vaccinia-virus-exposed juveniles; and EBV and vaccinia virus-naive infants. No significant titre variations for EBV were observed in the adults, but EBV-neutralising titres increased in the vaccinated juveniles, while antibodies to VCA of EBV remained unchanged. All nine vaccinated infants developed antibodies to MA (membrane antigen) with neutralising properties in vitro; three of these infants were infected by EBV via natural routes over a period of 16 months after vaccination and all ten unvaccinated control infants became infected. It has been shown for the first time that protection against and/or delay of EBV infection by the natural route is possible in humans and that live vaccinia vectors can be used and are efficacious.
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Affiliation(s)
- S Y Gu
- Institute of Virology, Chinese Academy of Preventive Medicine, Beijing
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24
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Abstract
Pigeon-liver malic enzyme has a tendency to aggregate at a large concentration of protein. The larger aggregates (hexamer and octamer) were demonstrated to be enzymically active with specific activity similar to that of the tetramer. When the enzyme was embedded in a reverse micellar system prepared by dissolving the surfactant sodium bis(2-ethylhexyl)-sulfosuccinate (AOT) in isooctane, the tetrameric enzyme dissociated into monomers. The dissociated monomers were also enzymically active but with diminished specific activity relative to the activity in aqueous media. The decreased enzyme activity in reverse micelles was due to interactions of surfactant with the enzyme molecules, suggesting that the cytosolic malic enzyme is located near the plasma membrane. When the dissociation was monitored by altering the degree of hydration of the system (represented by the ratio [H2O]/[AOT]), the detergent and organic solvent slightly affected KTD, the dissociation constant of tetramer to dimers (T <--> 2 D), but increased KDM, the dissociation constant of dimer to monomers (D <--> 2 M), by 1-2 orders of magnitude; this change caused a 2-3 orders of magnitude increase in the overall dissociation constant KTM (T <--> 4 M). The dissociation of the tetrameric malic enzyme to monomers was favored by approximately 16 kJ/mol in AOT/isooctane reverse micelles versus aqueous media. We propose water-shell and induced-fit models for the enzyme in AOT/isooctane reverse micelles at large and small [H2O]/[AOT] ratios to explain this data, respectively. The asymmetric quaternary structure of the enzyme [Lee, H. J. & Chang, G. G. (1990) FEBS Lett. 277, 175-179] was re-evaluated in terms of the subunit interactions and various interconvertible enzyme forms.
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Affiliation(s)
- G G Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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25
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Abstract
Pigeon liver malic enzyme was chemically attached to Sepharose 4B-CL beads. The enzyme lost approximately 50% of its original activity when immobilization was carried out with 5 mg CNBr/ml gel. Immobilization performed at pH 8.0 or pH 4.5 resulted in the formation of matrix-bound tetramer and monomer, respectively. Matrix-bound reconstituted tetramer was derived from matrix-bound monomer by mixing the latter with soluble enzyme at pH 4.5, then raised the pH of the solution to 8.0. The matrix-bound monomer was demonstrated to be enzymically fully active in terms of specific activity. The pH profile for the enzymic reaction was similar for both soluble and immobilized enzymes. However, the latter had a broader range for the optimum pH (pH 6.8-7.8). The Arrhenius plots for all immobilized enzyme forms were biphasic with inflection at approximately 27 degrees C. The apparent Michaelis constants for the substrates increased about 2-3-fold after immobilization. All immobilized enzyme forms, including the matrix-bound monomer, showed substrate inhibition at high concentrations of L-malate. Both high-affinity and low-affinity binding sites for Mn2+ existed for all immobilized enzyme forms. These results are consistent with an existing asymmetric model, but are not compatible with a sequential model for the enzyme tetramer. The immobilized enzyme was stable for at least four months at 4 degrees C. As compared to soluble enzyme, the immobilized enzyme was less inhibited by (NH4)2SO4 or NaCl. It was also resistant to inactivation with periodate-oxidized aminopyridine adenine dinucleotide phosphate, an affinity label for malic enzyme. Incubation of the immobilized enzyme (1.25 microM) with the reagent (5.6 mM) resulted in pseudo-first-order inactivation with a rate constant of 0.0108 min-1 that was at least an order of magnitude smaller than that for the soluble enzyme.
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Affiliation(s)
- G G Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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26
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Huang TM, Chang GG. Characterization of the tetramer-dimer-monomer equilibrium of the enzymatically active subunits of pigeon liver malic enzyme. Biochemistry 1992; 31:12658-64. [PMID: 1472502 DOI: 10.1021/bi00165a016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The tetrameric malic enzyme from pigeon liver was reversibly dissociated in the sequence of tetramer-dimer-monomer in an acidic environment (pH 4.5) or when the ionic strength or temperature of the solution was perturbed (0.2 M ammonium sulfate or < 10 degrees C). The dissociated monomer was enzymatically active according to the following criteria: (a) separation and direct activity staining of the monomer in the native gradient polyacrylamide gel, (b) activity staining of the monomer at its pI region in the isoelectric focusing gel, and (c) the enzyme showing lower but definite enzyme activity under conditions where only monomer existed in the solution. The catalytic constant (kcat) and specificity constant (kcat/KmMal) for the monomer were found to be 19 +/- 6 s-1 and 58 x 10(3) s-1.M-1, respectively, only one-seventh and one-seventeenth of those for the tetramer. Different types of interactions are involved in the monomer-monomer and dimer-dimer associations: (a) Two dissociation processes showed different pH dependences. The monomer-monomer interactions involve an amino acid with a side chain pKa value around 5.7, and an amino acid with a side chain pKa value of 7.2 is involved in the dimer-dimer association. (b) Ammonium sulfate up to 0.2 M only affects the monomer-monomer but not the dimer-dimer interactions. The Gibb's free energy, enthalpy, and entropy all have negative values for the above subunits' dissociations. The overall dissociation is an enthalpy-driven process. Association of the subunits to form dimers and tetramers involves salt-bridge, van der Waals, and hydrogen-bonding interactions.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T M Huang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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27
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Abstract
An improved method for the purification of human placental alkaline phosphatase is described. The partially purified enzyme from Sigma was further purified by successive Concanavalin A-Sepharose and Q-Sepharose chromatography. The whole procedure may be completed in one working day. Highly purified enzyme was obtained with a 39% yield. The intrinsic fluorescence of the enzyme decreased at elevated temperature. The conformation of the enzyme molecule was studied by the fluorescence quenching technique. Upward Stern-Volmer plots were obtained for the quenching data which suggested that, in addition to collisional quenching, static quenching was involved in the quenching mechanism. The dynamic and static quenching constants were found to be 0.7 +/- 0.16 M-1 and 0.44 +/- 0.1 M-1, respectively, using acrylamide as the quenching agent. The corresponding values were 0.43 +/- 0.23 M-1 and 0.84 +/- 0.18 M-1, respectively, with KI as the quenching agent. Mg2+ and PO4(3-) induced protein conformational changes which altered both the dynamic and static quenching constants. Mg2+ was found to be a non-essential activator for the placental alkaline-phosphatase-catalyzed hydrolysis of 4-nitrophenyl phosphate. At pH 9.8, Mg2+ increased Vmax by 1.2-fold without affecting the Kd of the substrate. The tetranitromethane-modified enzyme showed slower migration toward the anode on electrophoresis and increased Kd for Mg2+.
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Affiliation(s)
- T C Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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28
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Abstract
The kinetic mechanism of the cytosolic NADP(+)-dependent malic enzyme from cultured human breast cancer cell line was studied by steady-state kinetics. In the direction of oxidative decarboxylation, the initial-velocity and product-inhibition studies indicate that the enzyme reaction follows a sequential ordered Bi-Ter kinetic mechanism with NADP+ as the leading substrate followed by L-malate. The products are released in the order of CO2, pyruvate, and NADPH. The enzyme is unstable at high salt concentration and elevated temperature. However, it is stable for at least 20 min under the assay conditions. Tartronate (2-hydroxymalonate) was found to be a noncompetitive inhibitor for the enzyme with respect to L-malate. The kinetic mechanism of the cytosolic tumor malic enzyme is similar to that for the pigeon liver cytosolic malic enzyme but different from those for the mitochondrial enzyme from various sources.
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Affiliation(s)
- G G Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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29
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Chang GG, Wang JK, Huang TM, Lee HJ, Chou WY, Meng CL. Purification and characterization of the cytosolic NADP(+)-dependent malic enzyme from human breast cancer cell line. Eur J Biochem 1991; 202:681-8. [PMID: 1761063 DOI: 10.1111/j.1432-1033.1991.tb16423.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cytosolic NADP(+)-dependent malic enzyme from a cultured human breast cancer cell line was purified to near homogeneity by two highly efficient chromatography systems: Pharmacia-LKB Q-Sepharose anion-exchange chromatography and adenosine-2',5'-bisphosphate-agarose affinity chromatography. The overall yield was 27%. The enzyme is presumably a tetramer composed of four probably identical subunits of Mr 65,000, which is similar to the enzyme from other sources. The pI and optimum reaction pH values for the tumor malic enzyme are 5.5 and 7.2, respectively. At pH 6.9, most of the enzyme exists as monomers. Activation energy for the enzyme-catalyzed oxidative-decarboxylation reaction is 57.4 kJ/mol. The enzyme is strictly NADP+ dependent, as NAD+ cannot support the oxidative-decarboxylation reaction. ATP at low concentration inhibits the enzyme activity. Fumarate at concentrations up to 5 mM does not affect the enzymatic reaction rate. Therefore the tumor cytosolic malic enzyme, unlike the mitochondrial malic enzyme, is not an allosteric regulatory enzyme.
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Affiliation(s)
- G G Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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30
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Kam PL, Huang TM, Shiao MS, Lin LJ, Chang GG. Oxidation and cleavage of 3-aminopyridine adenine dinucleotide phosphate with periodate. J Biochem Biophys Methods 1990; 21:115-27. [PMID: 2177069 DOI: 10.1016/0165-022x(90)90059-l] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Treatment of 3-aminopyridine adenine dinucleotide phosphate with sodium periodate in the neutral pH resulted in oxidation of the ribose linked to 3-aminopyridine and cleavage of the dinucleotide into adenosine- and 3-aminopyridine-containing moieties. Separation of these moieties was afforded by thin-layer chromatography, high-performance liquid chromatography, and fast protein liquid chromatography. From fast atom bombardment mass spectra and nuclear magnetic resonance spectra, the adenosine-containing moiety was identified as 2'-phosphoadenosine 5'-phosphate while the aminopyridine moiety was present in a mixture of the hydrated 3-aminopyridine mononucleotide/nucleoside dialdehyde. Separation of the completely oxidized product by Pharmacia fast protein liquid chromatography gave three major peaks corresponding to 2'-phosphoadenosine 5'-phosphate, 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside, with minor amount of oxidized 3-aminopyridine mononucleotide. Thus the oxidized 3-aminopyridine adenine dinucleotide phosphate was shown to cleave by two pathways: it may either undergo beta-elimination to give 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside; or the phosphodiester linkage may be hydrolyzed to give 2'-phosphoadenosine 5'-phosphate and oxidized 3-aminopyridine mononucleotide. The latter compound may further undergo beta-elimination and eventually give oxidized 3-aminopyridine nucleoside. Hydrolysis could be prevented by storing the sample as lyophilized powder, while beta-elimination was diminished by lowering the storage temperature. We found that the lyophilized powder of oxidized 3-aminopyridine adenine dinucleotide phosphate can be stored at -50 degrees C for several months with minimum decomposition.
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Affiliation(s)
- P L Kam
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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31
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Abstract
Abstract
An immunoassay system based on enzyme immunoassay technology has been developed for quantitative panel testing. The system includes test card disposables, reagents, and an instrument. Patients' samples are processed semiautomatically in the instrument with minimum user intervention. The test card has multiple test areas at individual locations on a membrane solid phase so that simultaneous determinations from a single specimen are possible. Each panel also includes positive and negative reagent procedural controls. Factory-determined calibration curves for each analyte are provided in barcode form with each test kit. The reagents include a specimen dilution buffer, enzyme conjugate, and precipitogenic substrate. Up to 10 test cards at a time can be processed in random-access and continuous-access modes, with automated agitation of sample and reagents over the solid phase, temperature-controlled incubation, and membrane washing and reading, data reduction, and printout of results. The optical reader measures diffuse reflectance and features source intensity and wavelength compensation.
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Affiliation(s)
- J Donohue
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - M Bailey
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - R Gray
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - J Holen
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - T M Huang
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - J Keevan
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - C Mattimiro
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - C Putterman
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - A Stalder
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
| | - J Defreese
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
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32
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Donohue J, Bailey M, Gray R, Holen J, Huang TM, Keevan J, Mattimiro C, Putterman C, Stalder A, Defreese J. Enzyme immunoassay system for panel testing. Clin Chem 1989; 35:1874-7. [PMID: 2673584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
An immunoassay system based on enzyme immunoassay technology has been developed for quantitative panel testing. The system includes test card disposables, reagents, and an instrument. Patients' samples are processed semiautomatically in the instrument with minimum user intervention. The test card has multiple test areas at individual locations on a membrane solid phase so that simultaneous determinations from a single specimen are possible. Each panel also includes positive and negative reagent procedural controls. Factory-determined calibration curves for each analyte are provided in barcode form with each test kit. The reagents include a specimen dilution buffer, enzyme conjugate, and precipitogenic substrate. Up to 10 test cards at a time can be processed in random-access and continuous-access modes, with automated agitation of sample and reagents over the solid phase, temperature-controlled incubation, and membrane washing and reading, data reduction, and printout of results. The optical reader measures diffuse reflectance and features source intensity and wavelength compensation.
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Affiliation(s)
- J Donohue
- Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064
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33
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Abstract
The pH-induced reversible dissociation of pigeon liver malic enzyme (EC 1.1.1.40) was studied by combined use of chemical cross-linking and SDS/polyacrylamide-gel electrophoresis. The tetrameric enzyme showed a pH-dependent dissociation in an acidic environment. At pH values above 8.0 most molecules existed as tetramers. The enzyme was gradually dissociated at lower pH. When the pH was below 5.0 most of the enzyme was present as the monomeric forms. Reassociation of the subunits was accomplished by adjusting the pH to neutrality. The dissociation and reassociation were almost instantaneous. No trimer was detected. The pigeon liver malic enzyme was thus shown to have a double-dimer quaternary structure with D2 symmetry. In the presence of substrates, the monomer-dimer-tetramer equilibrium favours the direction of dissociation. Tartronate, an L-malate analogue, was found to be more effective than L-malate in this process. When the monomeric forms were immobilized, the enzyme subunits were found to be fully active in catalysis. A possible arrangement of the four identical subunits of the enzyme molecule is proposed to account for the results obtained in this investigation. The origin of the half-of-the-sites reactivity of pigeon liver malic enzyme is also discussed.
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Affiliation(s)
- G G Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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34
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Chang GG, Huang TM, Wuu JA. Mechanism of pigeon liver malic enzyme: modification of essential carboxyl groups. Proc Natl Sci Counc Repub China B 1985; 9:56-66. [PMID: 3843264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The maximum velocity of the reaction catalyzed by the pigeon liver malic enzyme depends on the ionization of a functional group of pKa 6.7. This pKa value is independent of temperature within the range 30 degrees-49 degrees C, suggesting the ionization of a carboxyl group. The enzyme activity is inactivated by N-ethyl-5-phenylisoxazolium-3'-sulfonate (Woodward reagent K) at pH 6.0 and 25 degrees C. N-Methylhydroxamine regenerates the enzymatic activity whereas glycine ethyl ester does not. The addition of Mn2+, NADP+, and L-malate to the incubation mixture decreases the inactivation rate, suggesting that the reaction takes place in the active center. The binding capacities of the modified enzyme with NADP+, L-malate, pyruvate, and Mn2+ are not impaired. The kinetic and chemical evidence indicates that the inactivation is due to the modification of a carboxyl group which may be from glutamyl or aspartyl residues of the enzyme. This carboxyl group might function as a general acid-base catalyst. A detailed mechanism in terms of the exact amino acid residues involved is proposed.
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Abstract
A simple, rapid, and inexpensive procedure for the determination of aminoacyl-tRNA synthetase activity is described. The assay is based on a green color formed between PPi and ammonium molybdate in the presence of mercaptoethanol. The sensitivity is in the nanomole range and is comparable with the conventional [32P]PPi-ATP exchange assay. Amino acid, ATP, magnesium ion, and most common reagents do not interfere with the color yield.
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Chang GG, Chang TC, Huang TM. Involvement of lysine residue in the nucleotide binding of pigeon liver malic enzyme: modification with affinity label periodate-oxidized NADP. Int J Biochem 1982; 14:621-7. [PMID: 6809509 DOI: 10.1016/0020-711x(82)90046-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
1. Periodate-oxidized NADP, a competitive inhibitor of malic enzyme with respect to NADP, inactivate the enzyme in mild conditions. 2. The inactivation is due to the modification of an essential lysine residue. 3. Two molecules of reagent were found to be incorporated into the enzyme tetramer after extensive modification. 4. Complete protection of malic enzyme from the oxidized NADP inactivation was afforded by NADP and its analogues. 5. The modified enzyme showed increased apparent Michaelis constant for the nucleotide coenzymes but the maximum velocity was decreased. 6. The binding between the modified enzyme and NADPH was impaired.
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Abstract
The reaction of pigeon liver malic enzyme (L-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) with dicarbonyl compounds (2,3-butanedione, methylglyoxal, 2,4-pentanedione, and phenylglyoxal) resulted in a rapid loss of its enzymatic activity. The inactivation showed pseudo-first-order kinetics for all the dicarbonyls studied. All the log (pseudo-first-order rate constants) vs. log (dicarbonyl concentration) plots had slopes of near one, indicating approx. 1 : 1 reagent-active site complexes. Butanedione inactivation was reversible and was buffer-dependent. Pentanedione-modified enzyme showed a new absorption peak at 310 nM. NADP could completely protect the enzyme from inactivation. Oxaloacetate, ADP, AMP, NMN and adenosine were also effective in protection. Complete inactivation of the enzyme was accompanied by a loss of about six arginine residues per enzyme monomer. Butanedione-modified enzyme still bound NADPH as shown by fluorescence titration, nor was it binding with NADP impaired as determined by equilibrium gel filtration. The arginine residues, therefore, do not function in the coenzyme binding. However, the binding between the modified enzyme and [14C]malate was significantly decreased. These results led us to conclude that the arginine residues of malic enzyme are involved in the binding of the carboxyl group of substrate malate.
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38
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Abstract
The reactions of pigeon liver malic enzyme (L-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) with tetranitromethane and N-acetylimidazole have been investigated to obtain information about the functional role of tyrosine residues in this enzyme. Incubation of the sulfhydryl-masked enzyme with tetranitromethane or N-acetylimidazole caused a time-dependent loss of all enzymatic activities of this enzyme. The absorption spectra of both the nitrated and acetylated enzyme indicated modification of tyrosine residues. The enzymatic activity of the acetylated enzyme was reversed by hydroxylamine. No amino group modification was observed. Preincubation of the enzyme with dicarboxylate substrate (or inhibitor), nucleotide coenzyme and divalent metal ions protected the enzyme against these reagents. The acetylated enzyme showed different kinetic properties from the native enzyme. The apparent Michaelis constants for malate and oxaloacetate increase by 2-5-fold. The binding between acetylated enzyme and NADPH was not abolished. These results strongly suggest the involvement of tyrosine residues in the dicarboxylic acid binding of malic enzyme.
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