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Chun K, Kim TH, Lee OS, Hirose K, Chung TD, Chung DS, Kim H. Structure-selective recognition by voltammetry: enantiomeric determination of amines using azophenolic crowns in aprotic solvent. Anal Chem 2007; 78:7597-600. [PMID: 17073433 DOI: 10.1021/ac061587o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [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
The enantiomeric recognition of amines by voltammetry using electroactive macrocyclic molecules, nitroazophenolic crown ethers, is reported. The oxidation potential of the nitroazophenol moiety in nitroazophenols with 18-crown-6 sensitively depends on the structure of alkyl amines. Based on this phenomenon, enantiomeric amines and even the quantitative assay of the R/S ratio in enantiomeric mixtures can be selectively recognized by using 18-crown-6 azophenol (3-H) with chiral centers. In the case of phenylglycinol, the association constants (K) of 3-H for the R and S forms have an R/S value of 3.5. The peak potential of the R form in square-wave voltammograms reproducibly differs from that of the S form by 32 mV, within which the peak potential linearly varies with the enantiomeric ratio. Free energy perturbation and molecular dynamics simulation provide deeper understanding of the enantiomeric recognition in this system. The theoretical analysis indicates that the free energy difference between diastereomeric complexes agrees well with the experimental results, and the pi-pi or charge-charge interaction plays a key role in enantiomeric recognition.
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Affiliation(s)
- Kyungmin Chun
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea
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102
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Abstract
The nanoporous platinum oxide (H1-ePtO) as a hydrogen ion-selective sensing material is reported. Bare nanoporous platinum oxides exhibit near-Nernstian behavior (e.g., -55 mV/pH in PBS), ignorable hysteresis, a short response time, and high precision, which are remarkably better than those of flat platinum oxides. The electrode potential of a nanoporous platinum oxide responds exclusively to hydrogen ion, which implies its usefulness as a solid-state pH sensor. In the present study, the performance of nanoporous platinum oxide was investigated and compared with that of IrOx in terms of selectivity and the influences of ionic strength, temperature, complexing ligands, and surfactants. H1-ePtO functions well as a pH-sensing solid-state material, and it is viewed as a promising alternative to IrOx. Interference by redox couples was successfully suppressed by covering the H1-ePtO surface with a protective layer, e.g., an electropolymerized polyphenol thin film. Since the nanoporous platinum oxide with such a protective layer is particularly suitable for miniaturization and micropatterning, our findings suggest its usefulness in applications such as solid-state pH sensors embedded in chip-based microanalysis systems.
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Affiliation(s)
- Sejin Park
- Center for Nano-Bio Applied Technology and Department of Chemistry, Sungshin Women's University, Seoul, Korea
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103
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Chun HG, Chung TD, Kim HC. Cytometry microchip using polymer-based saltbridge electrodes. Conf Proc IEEE Eng Med Biol Soc 2007; 2004:2584-6. [PMID: 17270803 DOI: 10.1109/iembs.2004.1403743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We developed a cytometry glass chip using polymer-based saltbridge electrodes. Saltbridge electrodes were placed at lateral sides of channel to increase the sensitivity and robustness of detection. The dimension of saltbridge electrodes which are exposed to channel was 50mum by 20mum (width, height). The saltbridge electrode was formed at a specific position in a predefined shape by photopolymerization technique. UV light sensitive monomer DMAC (dially dimethyl ammonium chloride) was used for polymerization. Polymer-based saltbridge electrode enabled the DC impedance analysis of the channel for cytometry. Moreover, the lateral positioning of saltbridge electrode is easily accomplished by photopolymerization technique. We validated the detection sensitivity of developed chip using 10mum fluorescent bead.
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Affiliation(s)
- H G Chun
- Dept. of Biomed. Eng., Seoul Nat. Univ., South Korea
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104
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Han JH, Boo H, Park S, Chung TD. Electrochemical oxidation of hydrogen peroxide at nanoporous platinum electrodes and the application to glutamate microsensor. Electrochim Acta 2006. [DOI: 10.1016/j.electacta.2005.12.060] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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105
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George R, Ramakrishnan V, Siebers JV, Chung TD, Keall PJ. Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy. Phys Med Biol 2006; 51:5305-19. [PMID: 17019040 DOI: 10.1088/0031-9155/51/20/015] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Respiratory gating can reduce the apparent respiratory motion during imaging and treatment; however, residual motion within the gating window remains. Respiratory training can improve respiratory reproducibility and, therefore, the efficacy of respiratory-gated radiotherapy. This study was conducted to determine whether residual motion during respiratory gating is affected by patient, tumour or treatment characteristics. The specific aims of this study were to: (1) identify significant characteristics affecting residual motion, (2) investigate time trends of residual motion over a period of days (inter-session) and (3) investigate time trends of residual motion within the same day (intra-session). Twenty-four lung cancer patients were enrolled in an Institutional Review Board (IRB)-approved protocol. For approximately five sessions, 331 four-minute, respiratory motion traces were acquired with free breathing, audio instructions and audio-visual biofeedback for each patient. The residual motion was quantified by the standard deviation of the displacement within the gating window. The generalized linear model was used to obtain coefficients for each variable within the model and to evaluate the clinical and statistical significance. The statistical significance was determined by a p-value<0.05, while effect sizes of 0.1 cm (one standard deviation) were considered clinically significant. This data analysis was applied to patient, tumour and treatment variables. Inter- and intra-session variations were also investigated. The only variable that was significant for both inhale- and exhale-based gating was disease type. In addition, visual-training displacement, breathing type and Karnofsky performance status (KPS) values were significant for inhale-based gating, and dose-per-fraction was significant for exhale-based gating. Temporal respiratory variations within and between sessions were observed for individual patients. However inter- and intra-session analyses did not show significant time trends on average for any of the variables considered. The lack of significant time trends within and between sessions indicates that on average (1) there is no significant learning period for breathing training, (2) the patients did not experience training-related fatigue and (3) the margin component to account for residual motion during gated radiotherapy appears to remain constant throughout the treatment.
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Affiliation(s)
- R George
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA, USA.
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106
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Oh WS, Chung TD, Kim J, Kim HS, Kim H, Hwang D, Kim K, Rha SG, Choe JI, Chang SK. Synthesis and Electrochemical Properties of Calix[4]arene-triester-monoquinones. Supramol Chem 2006. [DOI: 10.1080/10610279808034990] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Weon Seok Oh
- a Department of Chemistry , Chung-Ang University , Seoul , 156-756 , Korea
| | - Taek Dong Chung
- b Department of Chemistry and Center for Molecular Catalysis , Seoul National University , Seoul , 151-742 , Korea
| | - Jongwon Kim
- b Department of Chemistry and Center for Molecular Catalysis , Seoul National University , Seoul , 151-742 , Korea
| | - Hee-Soo Kim
- b Department of Chemistry and Center for Molecular Catalysis , Seoul National University , Seoul , 151-742 , Korea
| | - Hasuck Kim
- b Department of Chemistry and Center for Molecular Catalysis , Seoul National University , Seoul , 151-742 , Korea
| | - Dongmok Hwang
- c Department of Chemistry , Center for Biofunctional Molecules, Pohang University of Science and Technology , Pohang , 790-784 , Korea
| | - Kimoon Kim
- c Department of Chemistry , Center for Biofunctional Molecules, Pohang University of Science and Technology , Pohang , 790-784 , Korea
| | - Seung Gul Rha
- a Department of Chemistry , Chung-Ang University , Seoul , 156-756 , Korea
| | - Jong-In Choe
- a Department of Chemistry , Chung-Ang University , Seoul , 156-756 , Korea
| | - Suk-Kyu Chang
- a Department of Chemistry , Chung-Ang University , Seoul , 156-756 , Korea
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107
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Stavropoulos NE, Kim A, Nseyo UU, Tsimaris I, Chung TD, Miller TA, Redlak M, Nseyo UO, Skalkos D. Hypericum perforatum L. extract – Novel photosensitizer against human bladder cancer cells. Journal of Photochemistry and Photobiology B: Biology 2006; 84:64-9. [PMID: 16540336 DOI: 10.1016/j.jphotobiol.2006.02.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2005] [Revised: 12/22/2005] [Accepted: 02/02/2006] [Indexed: 11/21/2022]
Abstract
The polar methanolic fraction (PMF) of the Hypericum perforatum L. extract has recently been developed and tested as a novel, natural photosensitizer for use in the photodynamic therapy (PDT), and photodynamic diagnosis (PDD). PMF has been tested on HL-60 leukemic cells and cord blood hemopoietic progenitors. In the present study, the efficacy of PMF as a phototoxic agent against urinary bladder carcinoma has been studied using the T24 (high grade metastatic cancer), and RT4 (primary low grade papillary transitional cell carcinoma) human bladder cancer cells. Following cell culture incubation, PMF was excited using 630 nm laser light. The photosensitizer exhibited significant photocytotoxicity in both cell lines at a concentration of 60microg/ml, with 4-8 J/cm(2) light dose, resulting in cell destruction from 80% to 86%. At the concentration of 20microg/ml PMF was not active in either cell line. These results were compared with the results obtained in the same cell lines, under the same conditions with a clinically approved photosensitizer, Photofrin. Photofrin was used in the maximum clinically tolerable dose of 4microg/ml, and it was also excited with 630 nm laser light. In the T24 cell Photofrin exhibited slightly less photocytotocixity, compared with PMF, resulting in 77% cell death with 8J/cm(2) light dose. However, against the RT4 cells Photofrin resulted in minimal cell death (9%) with even 8J/cm(2) light dose. Finally, the type of cell death induced by PMF photoactivation was studied using flow cytometry and DNA laddering. Cell death by PMF photodynamic action in these two bladder cell lines is caused predominently by apoptosis. The reported significant photocytotoxicity, selective localization, natural abundance, easy, and inexpensive preparation, underscore that the PMF extract hold the promise of being a novel, effective PDT photosensitizer.
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Affiliation(s)
- N E Stavropoulos
- Department of Urology, Hatzikosta General Hospital, Makryianni Avenue, Ioannina, GR-45001, Greece.
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108
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Park S, Boo H, Chung TD. Electrochemical non-enzymatic glucose sensors. Anal Chim Acta 2006; 556:46-57. [PMID: 17723330 DOI: 10.1016/j.aca.2005.05.080] [Citation(s) in RCA: 611] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 05/25/2005] [Accepted: 05/26/2005] [Indexed: 11/19/2022]
Abstract
The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials.
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Affiliation(s)
- Sejin Park
- Center for Nano-Bio Applied Technology and Department of Chemistry, Sungshin Women's University, Seoul 136-742, Korea.
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109
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Boo H, Jeong RA, Park S, Kim KS, An KH, Lee YH, Han JH, Kim HC, Chung TD. Electrochemical Nanoneedle Biosensor Based on Multiwall Carbon Nanotube. Anal Chem 2005; 78:617-20. [PMID: 16408948 DOI: 10.1021/ac0508595] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [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
We report the fabrication and analytical functions of a biosensor based on a nanoneedle consisting of a multiwall carbon nanotube attached to the end of an etched tungsten tip. The devised electrode is the smallest needle-type biosensor reported to date. The nanoneedles prepared in this work are 30 nm in diameter and 2-3 microm in length. Dopamine and glutamate, which are physiologically important neurotransmitters, were successfully detected using these nanoneedles. Bare nanoneedles detected dopamine in the range from 100 to 1000 microM by differential pulse voltammetry, and enzyme-modified nanoneedles were able to respond to glutamate in the 100-500 microM range by potentiostatic amperometry.
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Affiliation(s)
- Hankil Boo
- Center for NanoBio Applied Technology and Department of Chemistry, Sungshin Women's University, 249-1 Dongsun-dong, Seongbuk-gu, Seoul 136-742, Republic of Korea
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110
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Abstract
Accurate modeling of the respiratory cycle is important to account for the effect of organ motion on dose calculation for lung cancer patients. The aim of this study is to evaluate the accuracy of a respiratory model for lung cancer patients. Lujan et al. [Med. Phys. 26(5), 715-720 (1999)] proposed a model, which became widely used, to describe organ motion due to respiration. This model assumes that the parameters do not vary between and within breathing cycles. In this study, first, the correlation of respiratory motion traces with the model f(t) as a function of the parameter n (n = 1, 2, 3) was undertaken for each breathing cycle from 331 four-minute respiratory traces acquired from 24 lung cancer patients using three breathing types: free breathing, audio instruction, and audio-visual biofeedback. Because cos2 and cos4 had similar correlation coefficients, and cos2 and cos1 have a trigonometric relationship, for simplicity, the cos1 value was consequently used for further analysis in which the variations in mean position (z0), amplitude of motion (b) and period (tau) with and without biofeedback or instructions were investigated. For all breathing types, the parameter values, mean position (z0), amplitude of motion (b), and period (tau) exhibited significant cycle-to-cycle variations. Audio-visual biofeedback showed the least variations for all three parameters (z0, b, and tau). It was found that mean position (z0) could be approximated with a normal distribution, and the amplitude of motion (b) and period (tau) could be approximated with log normal distributions. The overall probability density function (pdf) of f(t) for each of the three breathing types was fitted with three models: normal, bimodal, and the pdf of a simple harmonic oscillator. It was found that the normal and the bimodal models represented the overall respiratory motion pdfs with correlation values from 0.95 to 0.99, whereas the range of the simple harmonic oscillator pdf correlation values was 0.71 to 0.81. This study demonstrates that the pdfs of mean position (z0), amplitude of motion (b), and period (tau) can be used for sampling to obtain more realistic respiratory traces. The overall standard deviations of respiratory motion were 0.48, 0.57, and 0.55 cm for free breathing, audio instruction, and audio-visual biofeedback, respectively.
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Affiliation(s)
- R George
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia, USA
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111
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George R, Ramakrishnan V, Siebers JV, Chung TD, Keall PJ. WE-C-J-6C-02: Investigation of Variables Affecting Residual Motion for Respiratory Gated Radiotherapy. Med Phys 2005. [DOI: 10.1118/1.1998507] [Citation(s) in RCA: 2] [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: 11/07/2022] Open
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112
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Abstract
This paper reports a polyelectrolytic salt bridge-based electrode (PSBE), which is a key embedded unit in a microchip device that can size-selectively count microparticles and measure their velocities. The construction of salt bridges at specific locations within a microfluidic chip enables dc-driven electrical detection to be performed successfully. This is expected to be a competitive alternative to the optical methods currently used in conventional cell sorters. The PSBEs were fabricated by irradiating ultraviolet light over a patterned mask on the parts of interest, which were filled with an aqueous monomer solution containing diallyldimethylammonium chloride. A pair of such PSBEs was easily formed at the two lateral branches perpendicular to the main microchannel and was found to be very useful for dc impedometry. The human blood cells as well as the fluorescent microbeads passing between the two PSBEs produced impedance signals in proportional to their size. The information about the velocity of a microparticle was extracted from a doublet of the dc impedance signals, which were generated when cells or microbeads sequentially passed through two PSBE pairs separated from each other by a fixed distance. The plot of peak amplitude versus velocity of the moving microbeads and cells indicated only a slight correlation between the size and the velocity, which means that the peak amplitude of the dc impedance signals alone can provide information about the size of the cells in a mixture. The experimental results showed a screening rate of over 1000 cells s(-1) and a velocity of the cells of over 100 mm s(-1). Compared with the previously suggested electrical detection system based on metal electrodes, the sensitivity and selectivity in cell detection were remarkably improved. In addition, the detection unit including the operating circuit became innovatively simple and the whole device could be miniaturized.
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Affiliation(s)
- Honggu Chun
- Department of Biomedical Engineering, College of Medicine and Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea
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113
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Abstract
A new outer layer composition, consisting of polytetrafluoroethylene (PTFE), Kel-F oil, and Nafion, is suggested to minimize the detrimental effect of dissolved oxygen and to extend the linear response range of a glucose oxidase(GOx)-based sensor using nonconducting polymer. The morphology of Kel-F/PTFE/Kel-F/Nafion polymeric laminate was followed during fabrication by SEM. When Kel-F film was formed on the PTFE outer layer, the linear response was extended to 21 mM, at a sensitivity of 2.8 +/- 0.8 nA/mM mm2. We demonstrate that a sensor without Kel-F/PTFE/Kel-F/Nafion outer layer is relatively oxygen dependent, whereas by comparison a sensor with Kel-F/PTFE/Kel-F/Nafion outer layer is oxygen independent. The current of such a glucose sensor implanted in the subcutaneous tissue stabilized within 60 min, and the lag between blood glucose changes and sensor output was within 1 min. The in vivo characteristics of the glucose sensor described show great promise for one-point in vivo calibration.
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Affiliation(s)
- Sun Kil Kang
- Department of Biomedical Engineering, College of Medicine and Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, Seoul 110-744, Korea
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114
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Abstract
Mesoporous electrodes provide an unusual opportunity to observe the dramatic transition of the electrochemical potential distribution in vicinity to mesoporous surfaces as the ionic strength varies. The experimental results were in accordance with what the classical Gouy-Chapman theory predicts on the basis of the correlation between Debye length (kappa-1) and the diameter of mesopores. Using the phenomenon that the electrochemically effective area of mesoporous electrode depends on the ionic strength, the faradaic current density of dioxygen reduction could be controlled by the electrolyte concentration.
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Affiliation(s)
- Hankil Boo
- Department of Chemistry, Sungshin Women's University, 249-1 Dongsun-dong, Sungbuk-gu, Seoul 136-742, Korea
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115
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Abstract
Amperometric glucose sensors were fabricated using glucose oxidase (GOx) entrapped in zirconium hydrogenphosphate (ZrP), and their performance was evaluated. Reportedly, alpha-ZrP is one of the candidates that are expected to improve the stability of enzymes immobilized on solid surfaces. We intercalated GOxs into ZrP (GOx/ZrP), cast the GOx/ZrP suspension in polyvinylalcohol on a platinum electrode, and dried it in a vacuum oven. The morphological layered structure was investigated by scanning electron microscopy. The enzymatic activities, which were determined by open-circuit potentiometric technique, reached the highest when GOxs were immobilized in ZrP at ca. pH 5. In vitro tests showed good linear responses in the 0-25 mM range and the sensitivity of 0.14 nA mM(-1) at 0.4 V vs. Ag/AgCl. The sensors, as made, were stable for more than 3 days within a limited deterioration.
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Affiliation(s)
- Sejin Park
- Department of Chemistry, Sungshin Women's University, 249-1, Dongsun-dong, Seongbuk-gu, Seoul 136-742, Korea
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116
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Jeong RA, Hwang JY, Joo S, Chung TD, Park S, Kang SK, Lee WY, Kim HC. In vivo calibration of the subcutaneous amperometric glucose sensors using a non-enzyme electrode. Biosens Bioelectron 2003; 19:313-9. [PMID: 14615088 DOI: 10.1016/s0956-5663(03)00219-7] [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] [Indexed: 11/29/2022]
Abstract
A new two-point calibration method for the subcutaneous amperometric continuous glucose sensor is reported. The proposed method is based on direct measurement of the background current (I(o)) using a non-enzyme electrode. For in vivo test, three electrodes were implanted in rabbits. Two of the three were identical needle-type enzyme electrodes with perfluorinated polymer outer layers (Pt/enzyme layer/Kel-F/PTFE/Kel-F/Nafion) that were placed in subcutaneous tissue and in a vessel (ear artery), respectively. And one non-enzyme electrode with exactly the same membrane composition as those of other two was in the subcutaneous layer to measure the background current. Implantation in the subcutaneous layer generated many crevices on the protecting layers of the electrodes. The signals from enzyme electrodes were effectively corrected by the measured background current from the non-enzyme electrode. In addition, a telemetric monitoring system was developed and evaluated for in vivo continuous glucose monitoring in order to alleviate the problems of motion artifact.
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Affiliation(s)
- Ran-A Jeong
- Department of Biomedical Engineering, College of Medicine and Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, 28 Yongon Dong, Chongno Gu, Seoul 110-744, South Korea
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117
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Kim SJ, Park SJ, Kim IY, Chung TD, Kim HC, Kim SI. Thermal characteristics of interpenetrating polymer networks composed of poly(vinyl alcohol) and poly(N-isopropylacrylamide). J Appl Polym Sci 2003. [DOI: 10.1002/app.12794] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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118
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Abstract
Roughness of nanoscopic dimensions can be used to selectively enhance the faradaic current of a sluggish reaction. Using this principle, we constructed mesoporous structures on the surfaces of pure platinum electrodes responding even more sensitively to glucose than to common interfering species, such as L-ascorbic acid and 4-acetamidophenol. Good sensitivities, as high as 9.6 microA cm(-2) mM(-1), were reproducibly observed in the presence of high concentration of chloride ion. The selectivities, sensitivities, and stabilities determined experimentally have demonstrated the potential of mesoporous platinum as a novel candidate for nonenzymatic glucose sensors.
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Affiliation(s)
- Sejin Park
- Department of Biomedical Engineering, College of Medicine and Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea
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119
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Kim SJ, Park SJ, Chung TD, An KH, Kim SI. Properties of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N-isopropylacrylamide). J Appl Polym Sci 2003. [DOI: 10.1002/app.12471] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [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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120
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Abstract
A new type miniaturized glucose sensor with good selectivity and stable current response has been developed. The structure consists of a recessed rectangular microfabricated platinum electrode, inner layer of two electropolymerized nonconducting films, and outer bilayer of poly(tetrafluoroethylene) (Teflon) and polyurethane (PU) films. Glucose oxidase (GOx) is entrapped during the electropolymerization of a poly(m-phenylenediamine) (PMPD) film in an acetate buffer (AB) solution, on which a highly interference-resistive PMPD film is deposited in a phosphate buffered saline (PBS) solution. The second PMPD film causes no significant decrease in accessibility of glucose to GOx. The inner layer maintains less than 1% permeability to acetaminophen for 12 days. The fairly adhesive outer layer allows stable current response. Due to high permeability, the information about enzyme activity can be obtained without serious error in spite of outer layer intervening between enzymes and solution. The apparent Michaelis-Menten constant and the maximum steady-state current density were 24 mM and 80 microA cm(-2), respectively.
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Affiliation(s)
- Haesik Yang
- Microsystem Team, Electronics and Telecommunication Research Institute, Taejon, South Korea.
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121
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Chung TD, Jeong RA, Kang SK, Kim HC. Reproducible fabrication of miniaturized glucose sensors: preparation of sensing membranes for continuous monitoring. Biosens Bioelectron 2001; 16:1079-87. [PMID: 11679292 DOI: 10.1016/s0956-5663(01)00185-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [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: 10/18/2022]
Abstract
The immobilization process of glucose oxidase(GOx) in the poly(1,3-diaminobenzene) (poly(1,3-DAB)) network was closely investigated in situ using an electrochemical quartz crystal microbalance(EQCM). GOx captured in approximately 50 nm thick poly-1,3-DAB layer causes a 514 Hz frequency increase, corresponding to 541 ng, and distributes mostly in the outer part of the polymer film. The presence of poly-L-lysine and glutaraldehyde during electropolymerization of poly(1,3-DAB) improves sensitivity by raising the amount of GOx immobilized. Adding a protective membrane on to the enzyme layer from poly(tetrafluoroethylene) (PTFE) dispersed in aqueous media lets the entire fabrication procedure finish perfectly without nonaqueous solvent. The finalized needle-type glucose sensors show competent functions in sensitivity, stability, biocompatibility, lifetime, interference and reproducibility.
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Affiliation(s)
- T D Chung
- Department of Biomedical Engineering, College of Medicine, Medical Research Center, Seoul National University, 28 Yongon dong, Chongno Gu, Seoul 110-799, South Korea
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122
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Chung TD, Park J, Kim J, Lim H, Choi MJ, Kim JR, Chang SK, Kim H. Self-assembled monolayer of a redox-active calix[4]arene: voltammetric recognition of the Ba2+ ion in aqueous media. Anal Chem 2001; 73:3975-80. [PMID: 11534725 DOI: 10.1021/ac001050p] [Citation(s) in RCA: 37] [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: 11/29/2022]
Abstract
The Redox-active monolayer of a novel calix[4]arene recognizing redox-inactive ionic species by voltammetry is reported. Calix[4]arene-disulfide-diquinone, which is not only redox-active but is also a highly selective ionophore for the Ba2+ ion, spontaneously forms a stable and dense monolayer film on gold. The redox-active calixarene monolayer selectively recognizes Ba2+ ion in aqueous media, and the voltammetric signals are proportional to the ionic concentration. A new voltammetric peak can be detected by square-wave voltammetry upon adding a dilute solution containing Ba2+ ion having a concentration as low as 1.0 x 10(-6) M. The Langmuir plot (1/ip vs 1/[Ba2+]) shows a linear slope in the range from 1.0 x 10(-6) M to 1.0 x 10(-4) M. This modified electrode does not show any significant interference from alkali and alkaline earth metal ions except for Sr2+ and Ca2+. Only 100- and 500-fold concentrations of Sr2+ and Ca2+ ions, respectively, can lead to voltammetric responses comparable to that of Ba2+.
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Affiliation(s)
- T D Chung
- School of Chemistry and Molecular Engineering, Center for Molecular Catalysis, Seoul National University, Korea
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Kariv I, Cao H, Marvil PD, Bobkova EV, Bukhtiyarov YE, Yan YP, Patel U, Coudurier L, Chung TD, Oldenburg KR. Identification of inhibitors of bacterial transcription/translation machinery utilizing a miniaturized 1536-well format screen. J Biomol Screen 2001; 6:233-43. [PMID: 11689123 DOI: 10.1177/108705710100600405] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This report presents the miniaturization of a HTS screen to identify inhibitors of prokaryotic transcription-translation in a 1536-well format. The in vitro assay design utilized the bacterial expression machinery to drive expression of a firefly luciferase reporter gene, which was read as an endpoint luminesence measurement. This multicomponent system permits identification of inhibitors at different steps in this pathway. Successful miniaturization required integration of homogeneous assay formats, robust liquid-handling workstations, and second-generation imaging systems. Comparison of data from a triplicate 1536-well screen of a subset of a target library that had been previously validated and followed up for hit confirmation in a 384-well plate format confirmed that triplicate screening yields data of higher confidence and quality, eliminates the time-consuming and potentially error-prone step of cherry-picking, and reduces the number of false positives and negatives. The substantial savings of reagents and reduction of the numbers of plates to process obtained in a 1536-well format as compared to a 384-well format allowed a full triplicate evaluation of the entire library of 183,000 compounds at lower cost and in less time. The triplicate-screen statistics are consistent with a highly reliable data set with a coefficient of variation of 14.8% and Z' and Z values of 0.57 and 0.25, respectively. This screen resulted in the identification of 1,149 hits (0.63% hit rate), representing a compound population at 2.5 standard deviations from the mean cutoff. Furthermore, the data demonstrate good agreement between IC(50) values derived for this assay in a 1536-well format and 384-well format.
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Affiliation(s)
- I Kariv
- Leads Discovery Department, Dupont Pharmaceuticals Company, Wilmington, DE 19880, USA.
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Abstract
A homogeneous scintillation proximity assay (SPA) for detection of RNA transcripts is described. 3H-labeled RNA transcripts are hybridized in solution to biotinylated oligodeoxynucleotides (ODNs), which are then bound by streptavidin-coated, scintillant-embedded beads. Only bound 3H-labeled RNA transcripts are brought in close enough proximity to stimulate light emission from the beads. The results from this novel homogeneous assay correlated well with those obtained using the traditional filter-binding methods to measure RNA polymerase activity. The assay has been miniaturized to a 384-well format compatible with automated high-throughput screening. This SPA method has also been successfully used to probe RNA-accessible sites to hybridization, and thus should provide a useful tool for selecting effective antisense ODNs in antisense research.
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Affiliation(s)
- J Liu
- DuPont Pharmaceuticals Company, Experimental Station, E400/5442, P.O. Box 80400, Wilmington, DE 19880, USA.
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Chung TD, Anson FC. Electrochemical monitoring of proton transfer across liquid/liquid interfaces on the surface of graphite electrodes. Anal Chem 2001; 73:337-42. [PMID: 11199987 DOI: 10.1021/ac0009447] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Equilibrium partitioning of HClO4 between aqueous solutions and benzonitrile (BN) or nitrobenzene (NB) was measured and used to evaluate the pKa of the acid in the two organic solvents. The potential drop across the BN/ H2O interface was evaluated from the known potential drop across the NB/H2O interface and the voltammetrically measured formal potential of a ferrocenium/ferrocene redox couple confined within thin layers of the two organic solvents. The voltammetric reduction of tetrachloro-1, 4-benzoquinone in thin layers of BN was used to monitor changes in the concentration of protons in the layer during proton-consuming faradaic reactions. The rate of proton transfer from the aqueous to the nonaqueous phase across the BN/H2O interface was shown to be adequate to sustain proton-consuming reactions at the electrode/BN interface.
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Affiliation(s)
- T D Chung
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, USA
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127
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Chung TD, Park II, Ignacio L, Catchatourian R, Kopnick M, Davison E, Conrad G, Awan AM, Crawford D, Vijayakumar S. Television and news print media are effective in recruiting potential participants in a prostate cancer chemoprevention trial. Int J Cancer 2000; 90:302-4. [PMID: 11091355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- T D Chung
- Department of Radiation and Cellular Oncology, The University of Chicago, Illinois 60612, USA
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128
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McElroy KE, Bouchard PJ, Harpel MR, Horiuchi KY, Rogers KC, Murphy DJ, Chung TD, Copeland RA. Implementation of a continuous, enzyme-coupled fluorescence assay for high-throughput analysis of glutamate-producing enzymes. Anal Biochem 2000; 284:382-7. [PMID: 10964423 DOI: 10.1006/abio.2000.4740] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [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: 11/22/2022]
Abstract
Enzymatic formation of glutamate is critical to numerous biological pathways. However, current methods for assaying the activities of glutamate-forming enzymes are not particularly suitable for high-throughput screening in drug discovery. We present a continuous-read, fluorometric assay for high-throughput analysis of glutaminases. This assay is adapted to a microplate format and employs glutamate oxidase and horseradish peroxidase to couple glutamate formation to production of the fluorescent reporter molecule, resorufin, for enhancement of sensitivity (M. Zhou, Z. Diwu, N. Panchuk-Voloshina, and R. P. Haughland, 1997, Anal. Biochem. 253, 162-168). Described herein is the selection of suitable levels of coupling enzymes for optimal kinetic response and lag time of the reporter system, based on the kinetic characteristics of the individual coupling enzymes. Finally, implementation of the assay in a format for high-throughput kinetic analysis of glutaminases is demonstrated for Escherichia coli carbamoyl phosphate synthase. Derived kinetic constants are comparable to literature values determined using a variety of assay techniques.
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Affiliation(s)
- K E McElroy
- Chemical Enzymology Department, DuPont Pharmaceuticals Company, Experimental Station, Wilmington, Delaware 19880, USA
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129
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Marcinkeviciene J, Rogers MJ, Kopcho L, Jiang W, Wang K, Murphy DJ, Lippy J, Link S, Chung TD, Hobbs F, Haque T, Trainor GL, Slee A, Stern AM, Copeland RA. Selective inhibition of bacterial dihydroorotate dehydrogenases by thiadiazolidinediones. Biochem Pharmacol 2000; 60:339-42. [PMID: 10856428 DOI: 10.1016/s0006-2952(00)00348-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [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: 10/18/2022]
Abstract
Dihydroorotate dehydrogenase is a critical enzyme of de novo pyrimidine biosynthesis in prokaryotic and eukaryotic cells. Differences in the primary structure of the enzymes from Gram-positive and -negative bacteria and from mammals indicate significant structural divergence among these enzymes. We have identified a class of small molecules, the thiadiazolidinediones, that inhibit prototypical enzymes from Gram-positive and -negative bacteria, but are inactive against the human enzyme. The most potent compound in our collection functioned as a time-dependent irreversible inactivator of the bacterial enzymes with k(inact)/K(i) values of 48 and 500 M(-1) sec(-1) for the enzymes from Escherichia coli and Enterococcus faecalis, respectively. The data presented here indicate that it is possible to inhibit prokaryotic dihydroorotate dehydrogenases selectively while sparing the mammalian enzyme. Thus, this enzyme may represent a valuable target for the development of novel antibiotic compounds.
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Affiliation(s)
- J Marcinkeviciene
- Department of Chemical Enzymology, The DuPont Pharmaceuticals Co., Wilmington, DE 19880-0400, USA
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Zhang JH, Chung TD, Oldenburg KR. A Simple Statistical Parameter for Use in Evaluation and Validation of High Throughput Screening Assays. J Biomol Screen 2000; 4:67-73. [PMID: 10838414 DOI: 10.1177/108705719900400206] [Citation(s) in RCA: 5348] [Impact Index Per Article: 222.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ability to identify active compounds (³hits²) from large chemical libraries accurately and rapidly has been the ultimate goal in developing high-throughput screening (HTS) assays. The ability to identify hits from a particular HTS assay depends largely on the suitability or quality of the assay used in the screening. The criteria or parameters for evaluating the ³suitability² of an HTS assay for hit identification are not well defined and hence it still remains difficult to compare the quality of assays directly. In this report, a screening window coefficient, called ³Z-factor,² is defined. This coefficient is reflective of both the assay signal dynamic range and the data variation associated with the signal measurements, and therefore is suitable for assay quality assessment. The Z-factor is a dimensionless, simple statistical characteristic for each HTS assay. The Z-factor provides a useful tool for comparison and evaluation of the quality of assays, and can be utilized in assay optimization and validation.
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Affiliation(s)
- JH Zhang
- DuPont Pharmaceuticals Research Laboratories, Leads Discovery, DuPont Pharmaceuticals Company, Wilmington, Delaware
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132
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Zhang JH, Chung TD, Oldenburg KR. Confirmation of primary active substances from high throughput screening of chemical and biological populations: a statistical approach and practical considerations. J Comb Chem 2000; 2:258-65. [PMID: 10827934 DOI: 10.1021/cc9900706] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many biologically important substances are discovered through screening of relevant chemical or biological libraries. The ability to find the active substances ("hits") from any random collection is largely determined by the quality of the assay and screening conditions. When a large population is screened for a specific characteristic, each member of that population is usually tested only once. Errors in the measurements require additional follow-up tests to confirm that each hit from the primary screen is truly active. In this report, we present a statistical model system that predicts the reliability of hits from a primary test as affected by the error in the assay and the choice of the hit threshold (hit limit). The hit confirmation rate, as well as false positive (representing substances that initially fall above the hit limit but whose true activity are below the hit limit) and false negative (representing substances that initially fall below the hit limit but whose true activity are in fact greater than the hit limit) rates have been analyzed with this model by computational simulation. This model can also be used in screen validation and post-screening data analysis. The statistical analysis presented here has broad implications and is applicable to screening of any large population for any specific characteristic. Obvious applications include drug discovery, gene chip analysis, population biology, directed molecular evolution, biological panning, and combinatorial material sciences.
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Affiliation(s)
- J H Zhang
- Leads Discovery, Experimental Station, DuPont Pharmaceuticals Company, P.O. Box 80400, Wilmington, Delaware 19880-0400, USA
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Choi D, Lee SK, Chung TD, Kim H. Electrochemical Determination of Adsorption Isotherm of Mordant Red 19 on Mercury and Its Analytical Application for the Indirect Determination of Uranium. ELECTROANAL 2000. [DOI: 10.1002/(sici)1521-4109(200005)12:7<477::aid-elan477>3.0.co;2-e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
BACKGROUND In the human prostate cancer cell line LNCaP, interleukin (IL)-6 has been shown to regulate both growth and neuroendocrine (NE) differentiation. We recently observed that IL-6 mediated growth arrest in LNCaP by activating STAT 3. Since differentiation and growth arrest are often associated processes, we investigated whether STAT3 also mediated NE differentiation in this prostate cancer cell line. METHODS We treated previously characterized clones LNCaP-neo (neomycin-resistant LNCaP) and LNCaP-SF (LNCaP-STAT3 dominant negative mutant) with IL-6 and screened for NE differentiation by observing morphological changes and immunoblotting for two NE markers, neuron-specific enolase (NSE) and chromogranin A (ChA). To characterize further the role of STAT3 in growth arrest and differentiation, we transfected a wild-type STAT3 vector into PC-3 cells and generated a subclone PC-3-S3. In this clone, we assessed differentiation by observing morphological changes and determined growth responses by cell counting and clonogenic assays. RESULTS We observed that IL-6 induced formation of neurite extensions, morphologic features associated with NE differentiation, and enhanced expression of neuronal markers ChA and NSE in LNCaP-neo cells. In contrast, LNCaP-SF, possessing a dominant negative mutant form of STAT3, exhibited no characteristics of IL-6 induced NE differentiation. Furthermore, expression of a constitutively phosphorylated wild-type STAT3 in PC-3 cells inhibited growth and induced the formation of neurite extensions and NSE expression. CONCLUSIONS These results indicate that STAT3 is a mediator of both NE differentiation and growth inhibition in LNCaP and PC-3, suggesting a connection between growth inhibition and NE differentiation in prostate cancer.
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Affiliation(s)
- M T Spiotto
- Department of Radiation and Cellular Oncology and Division of Biological Sciences, Pritzker School of Medicine, University of Chicago, Chicago, Illinois 60637, USA
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135
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Abstract
BACKGROUND In prostate cancer, we and others have observed distinct phenotypic responses to interleukin-6 (IL-6), which acts either as a paracrine growth inhibitor in the LNCaP cell line or as an autocrine growth stimulator in PC-3, DU145, and TSU cell lines. To understand the underlying mechanism responsible for this phenotypic difference, we investigated differences in the IL-6-induced Janus kinase-signal transducers and activators of transcription (JAK-STAT) signal transduction pathway between these two phenotypes. METHODS Prostate cancer cell lines were assayed for STAT3 activity by immunoblotting, electrophoretic gel shift assays (EMSA), and a luciferase reporter assay to test for STAT3 protein expression, phosphorylation, DNA binding, and transcriptional activity. To address the physiological role of STAT3, we introduced a dominant-negative mutant of STAT3 into LNCaP cells and assayed the effects of IL-6 on cell growth of this stable transfectant by cell counting, clonogenic assays, and c-myc expression. RESULTS IL-6 induced transcriptional activity of STAT3 only in LNCaP. STAT3 was transcriptionally inactive in PC-3, TSU, and DU145 at the level of protein expression, tyrosine phosphorylation, and DNA binding/transcriptional activity, respectively. An isolated LNCaP subclone containing a dominant-negative mutant of STAT3, LNCaP-SF, did not show STAT3-DNA binding or transcriptional activity. LNCaP-SF exhibited a proliferative response to IL-6 as compared to the control LNCaP-neo clone, which underwent growth arrest. Unlike LNCaP-neo, LNCaP-SF was able form colonies and to maintain c-myc expression in the presence of IL-6. CONCLUSIONS STAT3 transcriptional activation correlates with the growth-inhibitory signal of IL-6 in LNCaP, suggesting that STAT3 transcriptional activity is an important determinant in the different phenotypic responses to IL-6 in prostate cancer.
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Affiliation(s)
- M T Spiotto
- Department of Radiation and Cellular Oncology, University of Chicago, and the Pritzker School of Medicine, Chicago, Illinois 60637, USA
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136
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Abstract
BACKGROUND A number of recent studies have identified interleukin (IL)-6 as an important regulator of prostate cancer growth. Here, we investigate the potential interaction of IL-6 with phosphatidylinositol (PI)-3 kinase, a key growth regulatory enzyme, in prostate cancer cell lines. METHODS Tyrosine phosphorylation of p85, the regulatory subunit of PI-3 kinase, in the human prostate cancer cell lines LNCaP and PC-3 was assessed by sequential immunoprecipitation with anti-p85 antibody and immunoblotting with anti-phosphotyrosine. The effects of wortmannin, an inhibitor of PI-3 kinase, and/or IL-6 on cell growth were assessed by MTT assays. DNA laddering experiments were performed to assay for programmed cell death. RESULTS Tyrosine phosphorylation of p85 is upregulated by IL-6 in both LNCaP and PC-3. IL-6 promotes coprecipitation of p85 with gp130, the signal-transducing component of the IL-6 receptor. Inhibition of PI-3 kinase with wortmannin induces programmed cell death in PC-3 cells. In contrast, wortmannin has no effect on LNCaP growth when used alone; however, combined with IL-6, wortmannin promotes apoptosis in these cells. CONCLUSIONS PI-3 kinase is involved in IL-6 signal transduction and delivers an antiapoptotic signal in human prostate cancer cell lines.
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Affiliation(s)
- T D Chung
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, Illinois 60637, USA.
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Zhang JH, Qi RC, Chen T, Chung TD, Stern AM, Hollis GF, Copeland RA, Oldenburg KR. Development of a carbon dioxide-capture assay in microtiter plate for aspartyl-beta-hydroxylase. Anal Biochem 1999; 271:137-42. [PMID: 10419628 DOI: 10.1006/abio.1999.4135] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [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: 11/22/2022]
Abstract
CO2-capture methods have been used for assaying many decarboxylating enzymes including hydroxylation-coupled decarboxylation reactions. The traditional CO2-capture method involves performing the reaction in capped tubes and radiometric measurement of trapped 14CO2 by scintillation counting. In this report, a 14CO2-capture method in a 96-well microtiter plate format has been developed and a phosphor imaging system has been employed for sample measurement. The new assay method has been used successfully to assay aspartyl-beta-hydroxylase activity in microtiter plate format. The results obtained here compare favorably with those obtained from the traditional tube method. The method is sensitive, suitable for high throughput, and generally applicable to many CO2-releasing enzyme assays.
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Affiliation(s)
- J H Zhang
- DuPont Pharmaceuticals Research Laboratories, DuPont Pharmaceuticals Company, Wilmington, Delaware 19880-0400, USA
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138
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Abstract
BACKGROUND We recently identified IL-6, a pleiotropic cytokine implicated in the neoplastic process of a variety of neoplasms, as a mediator of prostate cancer morbidity. In the present study, we investigated the expression of members of the IL-6 supergene family and related cytokines and the potential role of IL-6 in prostate cancer growth regulation. METHODS Five established human prostate cancer cell lines were screened by ELISA for production of granulocyte colony-stimulating factor (G-CSF), leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), oncostatin M (OSM), tumor necrosis factor (TNF), interleukin-1 (IL-1), and granulocyte macrophage colony-stimulating factor (GM-CSF). Expression of the ligand-binding component of the IL-6 receptor, IL-6Rp80, was evaluated by ELISA and RT-PCR. Sequential immunoprecipitation and immunoblotting were performed to assay for expression of the signal-transducing component of the IL-6 receptor, gp130. The effects of IL-6 on cell growth were assessed by MTT assays. RESULTS The three hormone-refractory cell lines, DU-145, TSU, and PC-3, secreted distinct combinations of cytokines (DU-145: IL-6, GM-CSF; TSU: IL-6, LIF; PC-3: IL-6, G-CSF, LIF, IL-1, GM-CSF), each uniformly expressing IL-6. In contrast, neither of the two hormone-dependent cell lines, LNCaP-ATCC and LNCaP-GW, secreted significant quantities of any of the cytokines analyzed. None of the cell lines secreted detectable quantities of OSM, CNTF, or TNF. All cell lines, irrespective of hormone status, expressed both Il-6Rp80 and gp130. Addition of IL-6 in vitro inhibited growth of hormone-dependent cells, but had no effect on hormone-refractory lines. Anti-IL-6 neutralizing antibody inhibited growth of hormone-refractory cells. CONCLUSIONS IL-6 appears to undergo a functional transition from paracrine growth inhibitor to autocrine growth stimulator during progression of prostate cancer to the hormone-refractory phenotype.
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Affiliation(s)
- T D Chung
- Department of Radiation and Cellular Oncology, University of Chicago, Illinois, USA.
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Chung TD, Kang SK, Kim H, Kim JR, Oh WS, Chang SK. Synthesis and Electrochemical Behavior of a New Water Soluble Ca2+-selective Ionophore Based on Calix[4]arene-triacid-monoquinone. CHEM LETT 1998. [DOI: 10.1246/cl.1998.1225] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chung TD, Mauceri HJ, Hallahan DE, Yu JJ, Chung S, Grdina WL, Yajnik S, Kufe DW, Weichselbaum RR. Tumor necrosis factor-alpha-based gene therapy enhances radiation cytotoxicity in human prostate cancer. Cancer Gene Ther 1998; 5:344-9. [PMID: 9917088] [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] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The purpose of the present study was to determine the therapeutic potential of combining radiotherapy with tumor necrosis factor (TNF)-alpha-based gene therapy in the human prostate cancer PC-3 xenograft. PC-3 cells are highly resistant to TNF-alpha-induced cytotoxicity in vitro. A modest enhancement of radiation killing was observed with the addition of TNF-alpha in clonogenic survival assays. Combined treatment with Ad.Egr-TNF, a replication-deficient adenovirus modified to express TNF-alpha following the exposure of infected cells to ionizing radiation (40 Gy administered at 5 Gy per fraction) in vivo, resulted in increased tumor control, as defined by a reduction of tumor volume, when compared with treatment with Ad.Egr-TNF alone or with radiation alone (P < .03). The improvement in tumor control was achieved without increasing acute normal tissue damage when compared with tissue injury from radiation alone. The results of these studies support further development and clinical application of genetic radiotherapy for human prostate cancer.
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Affiliation(s)
- T D Chung
- Department of Radiation & Cellular Oncology and Pritzker School of Medicine, University of Chicago, Illinois 60637, USA.
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Chung TD, Kang SK, Kim J, Kim HS, Kim H. Interaction between various alkylammonium ions and quinone-derivatized calix[4]arenes in aprotic media. J Electroanal Chem (Lausanne) 1997. [DOI: 10.1016/s0022-0728(97)00100-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Choi D, Chung TD, Kang SK, Lee SK, Kim T, Chang SK, Kim H. Electrochemical recognition of ammonium and alkali metal cations with calix[4]arenediquinone. J Electroanal Chem (Lausanne) 1995. [DOI: 10.1016/0022-0728(95)03946-e] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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145
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Hagen M, Tiley L, Chung TD, Krystal M. The role of template-primer interactions in cleavage and initiation by the influenza virus polymerase. J Gen Virol 1995; 76 ( Pt 3):603-11. [PMID: 7534813 DOI: 10.1099/0022-1317-76-3-603] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [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: 01/25/2023] Open
Abstract
An in vitro cleavage/initiation assay was used to analyse cleavage site choice and transcription initiation by the influenza virus polymerase. A synthetic mRNA which is cleaved by the polymerase to produce a single 11 base primer fragment was altered around this cleavage site. Depending upon the mutations made, alternative cleavage sites were used. This system was then used in extracts from recombinant vaccinia virus infected cells which express the polymerase. These extracts require the addition of a synthetic vRNA in order to induce cleavage and initiation activity. The data show that the choice of cleavage site is wholely controlled by the mRNA and does not depend upon interactions with the vRNA template. However, the site of initiation of the cleaved primer on the template is influenced by template-primer interactions.
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Affiliation(s)
- M Hagen
- Department of Virology, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492
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Chung TD, Cianci C, Hagen M, Terry B, Matthews JT, Krystal M, Colonno RJ. Biochemical studies on capped RNA primers identify a class of oligonucleotide inhibitors of the influenza virus RNA polymerase. Proc Natl Acad Sci U S A 1994; 91:2372-6. [PMID: 7510890 PMCID: PMC43373 DOI: 10.1073/pnas.91.6.2372] [Citation(s) in RCA: 41] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A synthetic 67-nt RNA substrate, containing a 32P-labeled cap-1 structure (m7G32pppGm) was specifically cleaved by the influenza virus RNA polymerase (EC 2.7.7.48) to yield a single capped 11-nt fragment capable of directly priming transcription. An analysis of systematic truncations of this RNA substrate demonstrated that an additional nucleotide beyond this cleavage site was required for cleavage. The minimal RNA chain length required for priming activity was found to be 9 nt, while in contrast an RNA chain length of at least 4 nt was required for efficient binding to the viral polymerase. On the basis of these chain length requirements we show that a pool of capped oligonucleotides too short to prime transcription, but long enough to bind with high affinity to the viral polymerase, are potent inhibitors of cap-dependent transcription in vitro.
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Affiliation(s)
- T D Chung
- Department of Virology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543-4000
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147
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Abstract
Influenza virus polymerase complexes that were expressed in the absence of genomic viral RNA and nucleoprotein were examined for endonuclease activity and transcriptase ability in vitro. Nuclear extracts of cells that express influenza virus polymerase through recombinant vaccinia virus infection did not display specific endonuclease activity in vitro. This polymerase presumably represents an early form of enzyme present in infected cells prior to ribonucleoprotein assembly. Upon addition of a virus-like model RNA template, containing the partially complementary sequence found at the ends of viral RNA, endonuclease activity is stimulated in a concentration-dependent and sequence-specific manner. Once stimulated, the polymerase is able to elongate from the added viral template. Thus, addition of viral template is required for polymerase activity, while the presence of nucleoprotein is not required for limited transcription. Also, full activation of this recombinant viral polymerase is dependent on the presence of both the 3' and 5' ends of the viral genome, as model RNA containing either end alone could not effectively trigger the endonuclease.
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Affiliation(s)
- M Hagen
- Department of Virology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08540
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148
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Smith CC, Kulka M, Wymer JP, Chung TD, Aurelian L. Expression of the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) is required for virus growth and neoplastic transformation. J Gen Virol 1992; 73 ( Pt 6):1417-28. [PMID: 1318943 DOI: 10.1099/0022-1317-73-6-1417] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The amino-terminal domain of the large subunit of herpes simplex virus type 2 (HSV-2) ribonucleotide reductase (ICP10) has protein kinase (PK) activity and properties similar to those of growth factor receptor kinases which can be activated to transforming potential. DNA sequences that encode the PK domain cause neoplastic transformation of immortalized cells. The studies described in this report used a spontaneous mutant (ts5-152) temperature-sensitive for the synthesis of ICP10 and the previously described ICP10 expression vectors to study the role of ICP10 expression in HSV-2 growth and neoplastic potential. The titres of the ts5-152 mutant are 1000-fold lower at 39 degrees C compared to 34 degrees C after 12 h post-infection. The efficiency of plaquing is 0.003. The growth defect at 39 degrees C correlates with decreased ICP10 synthesis. Sequence analysis of the PK domain of the ts5-152 ICP10 gene identified a pair of frameshift mutations resulting in a 19 amino acid residue substitution at positions 275 to 293 and a downstream single base pair mutation causing a substitution at position 309. Cloning of the mutant ICP10 gene from ts5-152 into a wild-type HSV-2 isolate resulted in a recombinant (859/152) with growth properties and rates of ICP10 synthesis at 39 degrees C similar to those of ts5-152. Cells transformed with u.v.-inactivated ts5-152, or the recombinant 859/152, have significantly decreased cloning efficiency in agarose at 39 degrees C, but only during the first 250 post-transfer population doublings. Anchorage-independent growth was observed in cells transfected with expression vectors pJW17 or pJW32 that express ICP10 or its PK domain, respectively. Cells transfected with the frameshift mutant pJW21 or the ICP10 carboxy-terminal vector pJW31 did not form clones in agarose.
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Affiliation(s)
- C C Smith
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201
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149
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Wymer JP, Aprhys CM, Chung TD, Feng CP, Kulka M, Aurelian L. Immediate early and functional AP-1 cis-response elements are involved in the transcriptional regulation of the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10). Virus Res 1992; 23:253-70. [PMID: 1320796 DOI: 10.1016/0168-1702(92)90112-m] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Expression from the promoter of the herpes simplex virus type 2 (HSV-2) large subunit of ribonucleotide reductase (ICP10) is stimulated by co-transfection with DNA that encodes the virion protein Vmw65 previously shown to activate in trans the transcription of all IE genes (Wymer et al., 1989). Specific cis response elements involved in ICP10 transcriptional regulation were studied by chloramphenicol acetyltransferase analysis with hybrid ICP10 promoter/CAT structural gene constructions containing wild type or site-directed mutations of the promoter sequences. The data indicate that Vmw65 activation requires an intact TAAT-GARAT motif while complex formation requires an intact Oct-1 element, and the AP-1 consensus elements in the ICP10 promoter are functional in vitro. Thus, expression from the wild type and GA-rich mutant constructions was enhanced 10-20-fold by co-transfection with DNA encoding Vmw65. The GARAT and POU homeobox (PHB) binding motifs were required for Vmw65 mediated activation but the mutant in the POU specific box (PSB) binding motif was activated at higher concentrations of Vmw65 DNA (1.0-3.0 micrograms). The PHB and PSB binding motifs were necessary for complex formation as determined by gel retardation analysis with in vitro synthesized OTF-1 and Vmw65 proteins. The GARAT and GA-rich elements were not required. CAT expression from pICP10-cat was enhanced by co-transfection with jun and fos encoding DNA, and the ICP10 promoter complexed with in vitro synthesized jun protein.
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Affiliation(s)
- J P Wymer
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201
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150
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Tan KB, Dorman TE, Falls KM, Chung TD, Mirabelli CK, Crooke ST, Mao J. Topoisomerase II alpha and topoisomerase II beta genes: characterization and mapping to human chromosomes 17 and 3, respectively. Cancer Res 1992; 52:231-4. [PMID: 1309226] [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: 12/26/2022]
Abstract
Human cells contain two topoisomerase II isozymes named topo II alpha and topo II beta. The complementary DNAs for both enzymes have been cloned. The topo II alpha and topo II beta complementary DNAs hybridized to unique sequences of human, rodent, and chicken DNAs in Southern blots. The human topo II alpha gene has previously been mapped to chromosome 17. We confirmed the chromosomal location of topo II alpha and mapped the topo II beta gene to chromosome 3. In addition, topo II beta exhibits genetic polymorphism as has been reported for topoisomerases I and II alpha.
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Affiliation(s)
- K B Tan
- Research and Development, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406
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