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Dai R, Lam OLT, Lo ECM, Li LSW, Wen Y, McGrath C. Orofacial functional impairments among patients following stroke: a systematic review. Oral Dis 2014; 21:836-49. [PMID: 25041135 DOI: 10.1111/odi.12274] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/11/2014] [Accepted: 06/23/2014] [Indexed: 11/27/2022]
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Wang H, Zhang C, Wu Y, Ai Y, Lee DYW, Dai R. Comparative pharmacokinetic study of two boswellic acids in normal and arthritic rat plasma after oral administration of Boswellia serrata extract or Huo Luo Xiao Ling Dan by LC-MS. Biomed Chromatogr 2014; 28:1402-8. [PMID: 24806456 DOI: 10.1002/bmc.3182] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 02/05/2014] [Accepted: 02/14/2014] [Indexed: 11/07/2022]
Abstract
Huo Luo Xiao Ling Dan (HLXLD), a Chinese herbal formula composed of 11 different herbs, has been used traditionally for the treatment of arthritis and other chronic inflammatory diseases. However, the pharmacokinetic profile of its anti-inflammatory bioactive compounds has not been elucidated. Boswellic acids are the bioactive compounds with potent anti-inflammatory activity isolated from Boswellia serrate which is one of the 11 herbs of HLXLD. The objective of the study was to compare the pharmacokinetics of the two bioactive bowsellic acids: 11-keto-β-boswellic acid and 3-O-acetyl-11-keto-β-boswellic following oral administration of HLXLD or Boswellia serrata extract alone in normal and arthritic rats. An LC-MS method was developed and validated for the determination of 11-keto-β-boswellic acid and 3-O-acetyl-11-keto-β-boswellic in the comparative pharmacokinetic study. The results showed that there were significant differences in pharmacokinetic parameters between normal and arthritic groups. Interestingly, the absorptions of two boswellic acids were significantly higher in HLXLD than Boswellia serrata extract alone, indicating the synergistic effect of other herbal ingredients in HLXLD. This comparative pharmacokinetic study provided direct evidence supporting the notion that the efficacy of a complex mixture such as HLXLD is better than that of single components in treating human diseases.
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Waryani B, Dai R, Zhao Y, Zhang C, Abbasi AR. Surface ultrastructure of the olfactory epithelium of loach fish,Triplophysa dalaica(Kessler, 1876) (Cypriniformes: Balitoridae: Nemacheilinae). ACTA ACUST UNITED AC 2013. [DOI: 10.1080/11250003.2013.771711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Qi Y, Li G, Zhou Y, Wang M, Bi K, Dai R. DETERMINATION OF FK506 IN RAT BLOOD BY LC-MS/MS AND EFFECT OF SILYMARIN ON ITS PHARMACOKINETICS. J LIQ CHROMATOGR R T 2012. [DOI: 10.1080/10826076.2011.629392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wu C, Dai R, Bai J, Chen Y, Yu Y, Meng W, Deng Y. Effect of Elaeagnus Conferta Roxb (Elaeagnaceae) Dry Fruit on the Activities of Hepatic Alcohol Dehydrogenase and Aldehyde Dehydrogenase in Mice. TROP J PHARM RES 2011. [DOI: 10.4314/tjpr.v10i6.9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Zhou Y, Qi Y, Yan X, Bi K, Chen X, Dai R. [Determination of six lignin components in crude and different processed products of Schisandra chinensis]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 2011; 36:3449-3452. [PMID: 22368854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
OBJECTIVE To compare the contents of lignin in crude and processed fruits of Schisandrae chinensis, and to explore the processing mechanism of S. chinensis fruits. METHOD Contents of schisandrin, schisandrol B, deoxyschisandrin, gomisin N, gamma-schizandrin and schisandrin C were determined by high performance liquid chromatography (HPLC). RESULT Except the content of Schisandrol B was higher or less in processed fruits than that in the crude, the other lignin contents of S. chinensis fruits in different processed products were higher than that in the crude. The alcohol-processed product had the highest content of lignin. CONCLUSION The contents of lignin have changed by different processed methods, and alcohol-processed method may be the best processed method.
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Dai R, Ren X, He X, Huo Y. Convenient analytical method for quantitative determination of 23 pesticide residues in herbs by gas chromatography-mass spectrometry. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 86:559-64. [PMID: 21468787 DOI: 10.1007/s00128-011-0264-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 03/22/2011] [Indexed: 05/22/2023]
Abstract
A convenient analytical method for quantitative characterization of 23 pesticides in three herbs has been developed. Pesticides tested included organochlorine, organophosphorus and pyrethroids. Primary secondary amine and graphitized carbon black as dispersive-SPE sorbent were applied to clean up the sample. Analytical method was established by using the technique of gas chromatography coupled with electron impact mass spectrometry in the selected ion monitoring mode (GC-MS-SIM). The recoveries of all pesticides were in the range of 78.4%-119.2% at three spiked levels of 5, 20 and 50 μg/kg, and the relative standard deviations were below 9.5%. The limits of detections of all pesticides were less than 3.0 μg/kg. This analytical method could be applied to the analysis of commonly used pesticides in commercial herbs.
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Zhu H, Shi J, Wei Z, Dai R, Zhang X. Methyl 2-{1-[(Z)-3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-yl-idene]ethyl-amino}-3-phenyl-propanoate. Acta Crystallogr Sect E Struct Rep Online 2010; 66:o1352. [PMID: 21579438 PMCID: PMC2979594 DOI: 10.1107/s1600536810017241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Accepted: 05/11/2010] [Indexed: 11/10/2022]
Abstract
The mol-ecule of the title compound, C(22)H(23)N(3)O(3), exists in the enamine-keto form. A strong intra-molecular N-H⋯O hydrogen bond occurs, generating an S(6) ring. The dihedral angle between the heterocycle and the adjacent phenyl ring is 3.75 (15)°.
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Liu Y, Li L, Dai R, Qu F, Geng L, Li XM, Deng Y. Assessment of the Enzymatic Activity and Inhibition using HPFA with a Microreactor, Trypsin, Absorbed on Immobilized Artificial Membrane. J Chromatogr Sci 2010; 48:150-5. [DOI: 10.1093/chromsci/48.2.150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Liu XJ, Ye HX, Li WP, Dai R, Chen D, Jin M. Relationship between psychosocial factors and onset of multiple sclerosis. Eur Neurol 2009; 62:130-6. [PMID: 19571540 PMCID: PMC2790740 DOI: 10.1159/000226428] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 05/12/2009] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the influence of psychosocial variables on patients with multiple sclerosis (MS) and the relationship between these variables and the onset of MS. BACKGROUND The current evidence indicates that many types of psychosocial factors are involved in the development and relapse of MS, and it has been suggested that they could serve as predictors as well. So far, little has been reported on the effect of psychosocial factors on MS and the relationship between psychosocial factors and the onset of MS. METHODS Forty-one patients, 15 males and 26 females, average age 37.44 +/- 12.24 years (mean +/- SD), were evaluated by the Life Event Scale, Eysenck Personality Questionnaire, Social Support Revaluate Scale and Symptom Check List 90 and compared with 41 equivalent healthy control subjects, 15 males and 26 females, average age 36.38 +/- 12.84 years (mean +/- SD). Disease, demographic, psychosocial and lifestyle factors were measured at baseline. Patients with MS were first diagnosed by 3 neurologists according to the Poser (1983) MS diagnostic criteria. RESULTS Significant differences were found between the MS and the control group in their negative emotions and symptoms such as depression, anxiety, obsession, phobia, tense interpersonal relationship and somatization disorder. Significant differences were found between the two groups in the total number of negative life events, their family problems and the utilization of social support. The scores for various negative emotions in the MS group correlated positively with those for neuroticisms in personality type, and negatively with those for introverted and extroverted personality. Many kinds of negative emotions in the MS group correlated positively with the total number of life events, negative life events and family problems. Many kinds of negative emotions in the MS group correlated negatively with the utilization of social support. CONCLUSION The psychosocial factors are closely associated with MS onset and may play important roles in the development of the disease.
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Liu A, Chen Y, Yang Z, Feng Y, Rui W, Luo W, Liu Y, Gonzalez FJ, Dai R. New metabolites of fenofibrate in Sprague-Dawley rats by UPLC-ESI-QTOF-MS-based metabolomics coupled with LC-MS/MS. Xenobiotica 2009; 39:345-54. [PMID: 19350456 DOI: 10.1080/00498250802680827] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Fenofibrate has been widely used for the treatment of dyslipidaemia with a long history. Species differences of its metabolism were reported, but its metabolites in rodent have not been fully investigated. Urine and plasma samples were collected before and after oral dosages of fenofibrate in Sprague-Dawley rats. Urine samples were subjected to ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) analysis, and projection to latent structures discriminant analysis was used for the identification of metabolites. New metabolites in urine and plasma were also studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The metabolism pathway was studied in rat hepatocytes. Synthesized and purchased authentic compounds were used for metabolite identification by LC-MS/MS. Five ever-reported metabolites were identified and another four new ones were found. Among these new metabolites, fenofibric acid taurine and reduced fenofibric acid taurine indicate new phase II conjugation pathway of fenofibrate.
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Singh V, Roy A, Castro R, McClure K, Dai R, Agrawal R, Greenberg RJ, Weiland JD, Humayun MS, Lazzi G. On the thermal elevation of a 60-electrode epiretinal prosthesis for the blind. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2008; 2:289-300. [PMID: 23853132 DOI: 10.1109/tbcas.2008.2003430] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this paper, the thermal elevation in the human body due to the operation of a dual-unit epiretinal prosthesis to restore partial vision to the blind affected by irreversible retinal degeneration is presented. An accurate computational model of a 60-electrode device dissipating 97 mW power, currently under clinical trials is developed and positioned in a 0.25 mm resolution, heterogeneous model of the human head to resemble actual conditions of operation of the prosthesis. A novel simple finite difference scheme combining the explicit and the alternating-direction implicit (ADI) method has been developed and validated with existing methods. Simulation speed improvement up to 11 times was obtained for the the head model considered in this work with very good accuracy. Using this method, solutions of the bioheat equation were obtained for different placements of the implant. Comparison with in-vivo experimental measurements showed good agreement.
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Chen J, Gu J, Zhao R, Dai R, Wang J. Simultaneous Nonchiral Determination of Artemisinin and Arteannuin B in Artemisia annua Using Circular Dichroism Detection. Chromatographia 2008. [DOI: 10.1365/s10337-008-0880-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Dai R, Iwama A, Wang S, Kapila YL. Disease-associated fibronectin matrix fragments trigger anoikis of human primary ligament cells: p53 and c-myc are suppressed. Apoptosis 2005; 10:503-12. [PMID: 15909113 DOI: 10.1007/s10495-005-1880-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Inflammation in periodontal disease is characterized by the breakdown of the extracellular matrix. This study shows that an inflammation-associated matrix breakdown fragment of fibronectin (FN) induces anoikis of human periodontal ligament (PDL) cells. This 40 kDa fragment was identified in human inflammatory crevicular fluid and is associated with disease status. Previously, we reported that a similar recombinant FN fragment triggered apoptosis of PDL cells by an alternate apoptotic signaling pathway that requires transcriptional downregulation of p53 and c-myc. Thus, to determine whether the physiologically relevant 40 kDa fragment triggers apoptosis in these cells, the 40 kDa fragment was generated and studied for its apoptotic properties. The 40 kDa fragment induces apoptosis of PDL cells, and preincubation of cells with intact vitronectin, FN, and to a limited extent collagen I, rescue this apoptotic phenotype. These data suggest that the 40 kDa fragment prevents PDL cell spreading, thereby inducing anoikis. The signaling pathway also involves a downregulation in p53 and c-myc, as determined by Western blotting and real time quantitative PCR. These data indicate that an altered FN matrix as is elaborated in inflammation induces anoikis of resident cells and thus may contribute to disease progression.
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Dai R, Li K, Li Q, Bi K. Determination of Mangiferin, Jateorrhizine, Palmatine, Berberine, Cinnamic Acid, and Cinnamaldehyde in the Traditional Chinese Medicinal Preparation Zi-Shen Pill by High-Performance Liquid Chromatography. J Chromatogr Sci 2004; 42:207-10. [PMID: 15154983 DOI: 10.1093/chromsci/42.4.207] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
High-performance liquid chromatography is employed to determine the contents of six marker components such as mangiferin, jateorrhizine, palmatine, berberine, cinnamic acid, and cinnamaldehyde in the traditional Chinese medicinal preparation Zi-Shen pill. The separation is performed on a C(18) column by stepwise gradient elution with water (0.2%, v/v, triethylamine adjusted to pH 4 with phosphoric acid)-methanol-acetonitrile (0.01 min, 98:0:2; 20 min, 80:5:15; 30 min, 65:13:22; and 55 min, 65:13:22) as the mobile phase at a flow rate of 0.9 mL/min, with UV detection at 280 nm. Six regression equations show good linear relationships between the peak area of each marker and concentration. The recoveries of the markers listed are 95.5%, 98.3%, 96.8%, 99.5%, 101.7%, and 102.1%, respectively. The repeatability and reproducibility (relative standard deviation) of the method are less than 2.5% and 3.3%, respectively.
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Dai R, Gao J, Bi K. High-Performance Liquid Chromatographic Method for the Determination and Pharmacokinetic Study of Mangiferin in Plasma of Rats Having Taken the Traditional Chinese Medicinal Preparation Zi-Shen Pill. J Chromatogr Sci 2004; 42:88-90. [PMID: 15023262 DOI: 10.1093/chromsci/42.2.88] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
A high-performance liquid chromatographic method for the determination and pharmacokinetic study of mangiferin in the plasma of rats that have been orally administered the traditional Chinese medicinal preparation Zi-Shen pill is established. Plasma samples taken from rats are pretreated by protein precipitation with acetonitrile. Separation of the main effective constituent mangiferin is accomplished on a C18 stationary phase and a mobile phase of methanol&-water (25:75, v/v) with 0.6% glacial acetic acid. The UV detection wavelength is set at 320 nm, and the detection limit for mangiferin in plasma is 0.163 micro g/mL. After validation, the method is used to take a limited view of pharmacokinetic profiles of the traditional Chinese medicinal preparation Zi-Shen pill.
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Zhang Y, Frejtag W, Dai R, Mivechi NF. Heat shock factor-4 (HSF-4a) is a repressor of HSF-1 mediated transcription. J Cell Biochem 2001; 82:692-703. [PMID: 11500947 DOI: 10.1002/jcb.1191] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Heat shock transcription factors (HSFs) regulate the expression of heat shock proteins and other molecular chaperones that are involved in cellular processes from higher order assembly to protein degradation and apoptosis. Among the human HSFs, HSF-4 is expressed as at least two splice variants. One isoform (HSF-4b) possesses a transcriptional activation domain, but this region is absent in the other isoform (HSF-4a). We have recently shown that the HSF-4a isoform represses basal transcription from heterologous promoters both in vitro and in vivo. Here we show that HSF-4a and HSF-4b have dramatically different effects on HSF-1-containing nuclear bodies, which form after heat shock. While the expression of HSF-4b colocalizes with nuclear granules, the expression of HSF-4a prevents their formation. In addition, there is a concurrent reduction of HSF-1 in the nucleus, and there is reduction in its DNA binding activity and in HSE-dependent transcription of a reporter gene. To better understand the mechanism by which HSF-4a represses transcription, we inducibly expressed HSF-4a in cells and found that HSF-4a binds to the heat shock element (HSE) during attenuation of the heat shock response. Thus HSF-4a is an active repressor of HSF-1-mediated transcription. This repressor function makes the HSF-4a isoform unique within the HSF family.
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He S, Dai R, Lu B, Cao C, Bai H, Jing B. Medial axis reformation: a new visualization method for CT angiography. Acad Radiol 2001; 8:726-33. [PMID: 11508751 DOI: 10.1016/s1076-6332(03)80579-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
RATIONALE AND OBJECTIVES The authors performed this study to evaluate a new method (medial axis reformation [MAR]) for visualizing three-dimensional vascular data at electron-beam computed tomographic (CT) angiography. MATERIALS AND METHODS MAR was performed automatically with a personal computer-based workstation. After the region of interest was edited, voxels were divided into groups according to their path lengths. Centroids of groups were connected to form the medial axis. Then, the medial axis was refined with multiscale medial response. Bifurcations were also detected and refined. Finally, curved sections were generated through the branches and laid out onto a single image by using a splitting method. The authors performed MAR during electron-beam CT angiography of coronary arteries, common carotid arteries, and iliac arteries. RESULTS MAR displayed curved sections of branched vessels on one image, cut through the axis of vessels to show the vessel diameter objectively, and allowed the viewing direction to be altered arbitrarily. CONCLUSION Results of preliminary applications demonstrate that MAR is a valuable new visualization method for CT angiography.
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Wang G, Huang H, Dai R, Lee KY, Lin S, Mivechi NF. Suppression of heat shock transcription factor HSF1 in zebrafish causes heat-induced apoptosis. Genesis 2001; 30:195-7. [PMID: 11477707 DOI: 10.1002/gene.1064] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Conrad CC, Choi J, Malakowsky CA, Talent JM, Dai R, Marshall P, Gracy RW. Identification of protein carbonyls after two-dimensional electrophoresis. Proteomics 2001; 1:829-34. [PMID: 11503207 DOI: 10.1002/1615-9861(200107)1:7<829::aid-prot829>3.0.co;2-r] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The oxidative modification of proteins plays a major role in a number of human diseases, but identity of the specific proteins that are most susceptible to oxidation has posed a difficult problem. Protein carbonyls are increased after oxidative stress, and after derivatization with 2,4-dinitrophenyl hydrazine (DNP) they can be detected by various analytical and immunological methods. Although high resolution two-dimensional electrophoresis (2-DE) can resolve virtually all proteins present in a cell or tissue it has been difficult to determine the oxidized proteins because the DNP-derivatization process alters the isoelectric points of proteins, and additional procedures must be utilized to remove reaction byproducts. These additional procedures can lead to loss of sample, and poor isoelectric resolution on immobilized pH gradient (IPG) strips. We have developed a method that allows the IPG strips to be derivatized with DNP directly following isoelectric focusing of the proteins. This method allows the visualization of oxidized proteins by 2-DE with high reproducibility.
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Frejtag W, Zhang Y, Dai R, Anderson MG, Mivechi NF. Heat shock factor-4 (HSF-4a) represses basal transcription through interaction with TFIIF. J Biol Chem 2001; 276:14685-94. [PMID: 11278480 DOI: 10.1074/jbc.m009224200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heat shock transcription factors (HSFs) regulate the expression of heat shock proteins (hsps), which are critical for normal cellular proliferation and differentiation. One of the HSFs, HSF-4, contains two alternative splice variants, one of which possesses transcriptional repressor properties in vivo. This repressor isoform inhibits basal transcription of hsps 27 and 90 in tissue culture cells. The molecular mechanisms of HSF-4a isoform-mediated transcriptional repression is unknown. Here, we present evidence that HSF-4a inhibits basal transcription in vivo when it is artificially targeted to basal promoters via the DNA-binding domain of the yeast transcription factor, GAL4. By using a highly purified, reconstituted in vitro transcription system, we show that HSF-4a represses basal transcription at an early step during preinitiation complex assembly, as pre-assembled preinitiation complexes are refractory to the inhibitory effect on transcription. This repression occurs by the HSF-4a isoform, but not by the HSF-4b isoform, which we show is capable of activating transcription from a heat shock element-driven promoter in vitro. The repression of basal transcription by HSF-4a occurs through interaction with the basal transcription factor TFIIF. TFIIF interacts with a segment of HSF-4a that is required for the trimerization of HSF-4a, and deletion of this segment no longer inhibits basal transcription. These studies suggest that HSF-4a inhibits basal transcription both in vivo and in vitro. Furthermore, this is the first report identifying an interaction between a transcriptional repressor with the basal transcription factor TFIIF.
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Lu B, Dai R, Jing B, Bai H, He S, Zhuang N, Wu Q, Zhu X. Evaluation of coronary artery bypass graft patency using three-dimensional reconstruction and flow study of electron beam tomography. Chin Med J (Engl) 2001; 114:466-72. [PMID: 11780405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
OBJECTIVE To establish and evaluate two protocols for the noninvasive visualization and assessment of coronary artery bypass graft (CABG) patency on electron beam tomography (EBT). METHODS Two hundred and fourteen consecutive patients who underwent coronary artery bypass graft surgery were scanned using both EBT angiography with 3-dimensional reconstruction and EBT flow study with time-density-curve analysis. RESULTS There were 589 CABGs evaluated in this study (10 grafts were excluded because of artifacts). Among them, 133 (98.5%) of 135 arterial grafts were patent, and 345 (77.7%) of 444 saphenous-vein grafts were patent. Within 5 years or between 5 and 10 years after operation, arterial graft patency exceeded venous graft patency (P < 0.001). Three-dimensional EBT angiography achieved higher sensitivity, specificity and accuracy (97.7%, 94.1% and 96.7%, respectively) than did EBT flow study (88.4%, 82.4% and 85.2%, respectively) for evaluating occlusion or patency of CABG. The intra-graft flow of patent arterial and venous grafts were 4.9 +/- 2.2 ml.min-1.g-1 and 6.9 +/- 2.8 ml.min-1.g-1, respectively (P < 0.001). CONCLUSION The combination of EBT three-dimensional reconstruction and flow study can be more effective in the assessment of CABG anatomy and quantification of patent CABG blood flow.
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Dai R. Interventional therapy for congenital heart disease (CHD). Chin Med J (Engl) 2001; 114:548. [PMID: 11780426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
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Shou M, Dai R, Cui D, Korzekwa KR, Baillie TA, Rushmore TH. A kinetic model for the metabolic interaction of two substrates at the active site of cytochrome P450 3A4. J Biol Chem 2001; 276:2256-62. [PMID: 11054425 DOI: 10.1074/jbc.m008799200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In many cases, CYP3A4 exhibits unusual kinetic characteristics that result from the metabolism of multiple substrates that coexist at the active site. In the present study, we observed that alpha-naphthoflavone (alpha-NF) exhibited a differential effect on CYP3A4-mediated product formation as shown by an increase and decrease, respectively, of the carboxylic acid (P(2)) and omega-3-hydroxylated (P(1)) metabolites of losartan, while losartan was found to be an inhibitor of the formation of the 5,6-epoxide of alpha-NF. Thus, to address this problem, a kinetic model was developed on the assumption that CYP3A4 can accommodate two distinct and independent binding domains for the substrates within the active site, and the resulting velocity equations were employed to predict the kinetic parameters for all possible enzyme-substrate species. Our results indicate that the predicted values had a good fit with the experimental observations. Therefore, the kinetic constants can be used to adequately describe the nature of the metabolic interaction between the two substrates. Applications of the model provide some new insights into the mechanism of drug-drug interactions at the level of CYP3A4.
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He S, Dai R, Chen Y, Bai H. Optimal electrocardiographically triggered phase for reducing motion artifact at electron-beam CT in the coronary artery. Acad Radiol 2001; 8:48-56. [PMID: 11201457 DOI: 10.1016/s1076-6332(03)80743-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
RATIONALE AND OBJECTIVES The authors performed this study to (a) investigate coronary movement with electron-beam computed tomography (CT) and (b) find the optimal electrocardiographic (ECG) triggering phase for eliminating motion artifact. MATERIALS AND METHODS One hundred fifty-one patients without arrhythmia were examined with electron-beam CT. First, movie scans were obtained to create displacement and velocity graphs of coronary artery movement. Then, a volume scan with an exposure time of 100 msec was obtained with various ECG trigger settings. RESULTS Movement patterns of coronary arteries varied with heart rate. Optimal triggering phase was before atrial systole (near 71% of the R-R interval) when heart rate was slower than 68 beats per minute and at ventricular end systole when heart rate was fast. Rate of severe motion artifacts decreased from 43% to 0% when triggering was altered from 80% of the R-R interval to the individual optimal value. Experimental values of the optimal phase at different heart rates were derived, and severe motion artifact was only 3.0% with these values. CONCLUSION ECG triggering set according to the heart rate enables a great reduction in motion artifacts at electron-beam CT with a 100-msec exposure time. The results may have implications for magnetic resonance imaging of the coronary artery.
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