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Zhao K, Wang W, Rando OJ, Xue Y, Swiderek K, Kuo A, Crabtree GR. Rapid and phosphoinositol-dependent binding of the SWI/SNF-like BAF complex to chromatin after T lymphocyte receptor signaling. Cell 1998; 95:625-36. [PMID: 9845365 DOI: 10.1016/s0092-8674(00)81633-5] [Citation(s) in RCA: 596] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Lymphocyte activation is accompanied by visible changes in chromatin structure. We find that antigen receptor signaling induces the rapid association of the BAF complex with chromatin. PIP2, which is regulated by activation stimuli, is sufficient in vitro to target the BAF complex to chromatin, but it has no effect on related chromatin remodeling complexes containing SNF2L or hISWI. Purification and peptide sequencing of the subunits of the complex revealed beta-actin as well as a novel actin-related protein, BAF53. beta-actin and BAF53 are required for maximal ATPase activity of BRG1 and are also required with BRG1 for association of the complex with chromatin/matrix. This work indicates that membrane signals control the activity of the mammalian SWI/SNF or BAF complex and demonstrates a direct interface between signaling and chromatin regulation.
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Abstract
Diets rich in fruits and vegetables delay the onset of many age-related diseases, and contain a complex mixture of antioxidants (including ascorbate, carotenoids, vitamin E and other phenolics such as the flavonoids). However, diet also contains pro-oxidants, including iron, copper, H2O2, haem, lipid peroxides and aldehydes. Nitrite is frequently present in diet, leading to generation of reactive nitrogen species in the stomach. In considering the biological importance of dietary antioxidants, attention has usually focussed on those that are absorbed through the gastrointestinal tract into the rest of the body. In the present paper we develop the argument that the high levels of antioxidants present in certain foods (fruits, vegetables, grains) and beverages (e.g. green tea) play an important role in protecting the gastrointestinal tract itself from oxidative damage, and in delaying the development of stomach, colon and rectal cancer. Indeed, carotenoids and flavonoids do not seem to be as well absorbed as vitamins C and E. Hence their concentrations can be much higher in the lumen of the GI tract than are ever achieved in plasma or other body tissues, making an antioxidant action in the GI tract more likely. Additional protective mechanisms of these dietary constituents (e.g. effects on intercellular communication, apoptosis, cyclooxygenases and telomerase) may also be important.
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Abstract
The mammalian BAF complex regulates gene expression by modifying chromatin structure. In this report, we identify 80 genes activated and 2 genes repressed by the BAF complex in SW-13 cells. We find that prior binding of NFI/CTF to the NFI/CTF binding site in CSF1 promoter is required for the recruitment of the BAF complex and the BAF-dependent activation of the promoter. Furthermore, the activation of the CSF1 promoter requires Z-DNA-forming sequences that are converted to Z-DNA structure upon activation by the BAF complex. The BAF complex facilitates Z-DNA formation in a nucleosomal template in vitro. We propose a model in which the BAF complex promotes Z-DNA formation which, in turn, stabilizes the open chromatin structure at the CSF1 promoter.
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Zhao K, Hart CM, Laemmli UK. Visualization of chromosomal domains with boundary element-associated factor BEAF-32. Cell 1995; 81:879-89. [PMID: 7781065 DOI: 10.1016/0092-8674(95)90008-x] [Citation(s) in RCA: 244] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have purified two proteins from Drosophila that bind to the scs' boundary element of the hsp70 domain at locus 87A7. Their palindromic binding sites (CGATA-TATCG) symmetrically abut the previously mapped hypersensitive site of scs'. We have cloned a cDNA for one of these proteins, BEAF-32 (boundary element-associated factor of 32 kDa). It encodes a novel protein that is bound to scs' but not scs in vivo. Immunostaining localizes BEAF to hundreds of interbands and many puff boundaries on polytene chromosomes, suggesting that a chromosomal domain consists of a band (or puff) and part of the flanking interbands. Enhancer blocking assays implicate the palindromic binding site in boundary function. The lack of enhancer blocking in transiently transfected cells suggests an involvement of chromatin, nuclear structure, or both in boundary function.
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Zhao K, Käs E, Gonzalez E, Laemmli UK. SAR-dependent mobilization of histone H1 by HMG-I/Y in vitro: HMG-I/Y is enriched in H1-depleted chromatin. EMBO J 1993; 12:3237-47. [PMID: 8344261 PMCID: PMC413591 DOI: 10.1002/j.1460-2075.1993.tb05993.x] [Citation(s) in RCA: 197] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An experimental assay was developed to search for proteins capable of antagonizing histone H1-mediated general repression of transcription. T7 RNA polymerase templates containing an upstream scaffold-associated region (SAR) were highly selectively repressed by H1 relative to non-SAR control templates. This is due to the nucleation of H1 assembly into flanking DNA brought about by the numerous A-tracts (AT-rich sequences containing short homopolymeric runs of dA.dT base pairs) of the SAR. Partial, selective titration of these A-tracts by the high mobility group (HMG) protein HMG-I/Y led to the complete derepression of transcription from the SAR template by inducing the redistribution of H1 on to non-SAR templates. SARs are associated with many highly transcribed regulated genes where they may serve to facilitate the HMG-I/Y-mediated displacement of histone H1 in chromatin. Indeed, HMG-I/Y was found to be strongly enriched in the H1-depleted subfraction which can be isolated from chromatin.
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Halliwell B, Zhao K, Whiteman M. Nitric oxide and peroxynitrite. The ugly, the uglier and the not so good: a personal view of recent controversies. Free Radic Res 1999; 31:651-69. [PMID: 10630688 DOI: 10.1080/10715769900301221] [Citation(s) in RCA: 196] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Nitric oxide, a gaseous free radical, is poorly reactive with most biomolecules but highly reactive with other free radicals. Its ability to scavenge peroxyl and other damaging radicals may make it an important antioxidant in vivo, particularly in the cardiovascular system, although this ability has been somewhat eclipsed in the literature by a focus on the toxicity of peroxynitrite, generated by reaction of O2*- with NO* (or of NO- with O2). On balance, experimental and theoretical data support the view that ONOO- can lead to hydroxyl radical (OH*) generation at pH 7.4, but it seems unlikely that OH* contributes much to the cytotoxicity of ONOO-. The cytotoxicity of ONOO- may have been over-emphasized: its formation and rapid reaction with antioxidants may provide a mechanism of using NO* to dispose of excess O2*-, or even of using O2*- to dispose of excess NO*, in order to maintain the correct balance between these radicals in vivo. Injection or instillation of "bolus" ONOO- into animals has produced tissue injury, however, although more experiments generating ONOO- at steady rates in vivo are required. The presence of 3-nitrotyrosine in tissues is still frequently taken as evidence of ONOO- generation in vivo, but abundant evidence now exists to support the view that it is a biomarker of several "reactive nitrogen species". Another under-addressed problem is the reliability of assays used to detect and measure 3-nitrotyrosine in tissues and body fluids: immunostaining results vary between laboratories and simple HPLC methods are susceptible to artefacts. Exposure of biological material to low pH (e.g. during acidic hydrolysis to liberate nitrotyrosine from proteins) or to H2O2 might cause artefactual generation of nitrotyrosine from NO2- in the samples. This may be the origin of some of the very large values for tissue nitrotyrosine levels quoted in the literature. Nitrous acid causes not only tyrosine nitration but also DNA base deamination at low pH: these events are relevant to the human stomach since saliva and many foods are rich in nitrite. Several plant phenolics inhibit nitration and deamination in vitro, an effect that could conceivably contribute to their protective effects against gastric cancer development.
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Abstract
The abundant cytoskeletal protein actin has numerous cytoplasmic roles. Although there are many reports of the presence of actin in the nucleus, in general they have been discounted as artifactual. However, recent work has begun to provide evidence for important roles for actin in nuclear processes ranging from chromatin remodelling to splicing. In addition, several regulators of actin polymerization are localized to the nucleus or translocate to the nucleus in a regulated manner, suggesting that there is some function of actin in the nucleus that is subject to regulation. This review discusses the evidence for actin in the nucleus and summarizes recent work suggesting that actin or actin-related proteins are involved in the regulation of nuclear processes such as chromatin remodelling.
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Abstract
Immunization with a phosphonate monoester transition-state analog of cocaine provided monoclonal antibodies capable of catalyzing the hydrolysis of the cocaine benzoyl ester group. An assay for the degradation of radiolabeled cocaine identified active enzymes. Benzoyl esterolysis yields ecgonine methyl ester and benzoic acid, fragments devoid of cocaine's stimulant activity. Passive immunization with such an artificial enzyme could provide a treatment for dependence by blunting reinforcement.
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Goodman M, Morgan RW, Ray R, Malloy CD, Zhao K. Cancer in asbestos-exposed occupational cohorts: a meta-analysis. Cancer Causes Control 1999; 10:453-65. [PMID: 10530617 DOI: 10.1023/a:1008980927434] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To examine existing asbestos-exposed occupational cohorts and apply a meta-analytic technique to determine the magnitude of association between exposure and lung cancer and to investigate other cancer sites that may be related to such an exposure. METHODS We summarized the data from 69 asbestos-exposed occupational cohorts reporting on cancer morbidity and mortality. Data were extracted regarding numbers of deaths for each cancer, numbers of mesotheliomas, occupations and latency for respiratory, gastrointestinal, urinary and lymphohematopoietic cancers. For each cancer, we calculated a meta-SMR and examined heterogeneity of results using a chi-square test and by calculating a Z-statistic for each study. To examine the dose-response effect, we divided the studies into tertiles according to the percentage of mesothelioma deaths that served as a proxy estimation of asbestos exposure. RESULTS Lung cancer data demonstrated meta-SMRs of 163 and 148 with and without latency, respectively, with significant heterogeneity of results even after stratification according to occupational groups. Stratification of lung cancer studies according to percentage of mesothelioma deaths showed a dose-response effect. Z-scores ranged from -12.21 to + 29.49. Analysis for laryngeal cancer yielded meta-SMRs of 157 and 133 with and without latency, respectively, demonstrating homogeneous results across studies but accompanied by no evidence of a dose-response effect. Data for gastrointestinal cancers showed no evidence of a significant association and no dose-response effect. Kidney cancer demonstrated statistically non-significant meta-SMRs of 120 (95% CI 88-160) and 111 (95% CI 94-131) with and without latency respectively. CONCLUSIONS This meta-analysis demonstrates a wide variability of the association between occupational asbestos and lung cancer. There was a suggestion of an association between asbestos and laryngeal carcinoma and no clear association with other cancers.
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Meta-Analysis |
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10
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Resnick-Silverman L, St Clair S, Maurer M, Zhao K, Manfredi JJ. Identification of a novel class of genomic DNA-binding sites suggests a mechanism for selectivity in target gene activation by the tumor suppressor protein p53. Genes Dev 1998; 12:2102-7. [PMID: 9679054 PMCID: PMC317007 DOI: 10.1101/gad.12.14.2102] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There are two response elements for p53 in the promoter of the gene for the cyclin-dependent kinase inhibitor p21. The binding of p53 to the 5' site was enhanced by incubation with monoclonal antibody 421, whereas the binding of p53 to the 3' site was inhibited. Mutational analysis showed that a single-base change caused one element to behave like the other. A response element in the human cdc25C promoter is bound by p53 with properties similar to the 3' site. These results identify two classes of p53-binding sites and suggest a mechanism for target gene selectivity by p53.
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research-article |
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11
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Mets B, Winger G, Cabrera C, Seo S, Jamdar S, Yang G, Zhao K, Briscoe RJ, Almonte R, Woods JH, Landry DW. A catalytic antibody against cocaine prevents cocaine's reinforcing and toxic effects in rats. Proc Natl Acad Sci U S A 1998; 95:10176-81. [PMID: 9707620 PMCID: PMC21481 DOI: 10.1073/pnas.95.17.10176] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/1998] [Accepted: 06/29/1998] [Indexed: 11/18/2022] Open
Abstract
Cocaine addiction and overdose have long defied specific treatment. To provide a new approach, the high-activity catalytic antibody mAb 15A10 was elicited using a transition-state analog for the hydrolysis of cocaine to nontoxic, nonaddictive products. In a model of cocaine overdose, mAb 15A10 protected rats from cocaine-induced seizures and sudden death in a dose-dependent fashion; a noncatalytic anticocaine antibody did not reduce toxicity. Consistent with accelerated catalysis, the hydrolysis product ecgonine methyl ester was increased >10-fold in plasma of rats receiving mAb 15A10 and lethal amounts of cocaine. In a model of cocaine addiction, mAb 15A10 blocked completely the reinforcing effect of cocaine in rats. mAb 15A10 blocked cocaine specifically and did not affect behavior maintained by milk or by the dopamine reuptake inhibitor bupropion. This artificial cocaine esterase is a rationally designed cocaine antagonist and a catalytic antibody with potential for medicinal use.
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research-article |
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Hart CM, Zhao K, Laemmli UK. The scs' boundary element: characterization of boundary element-associated factors. Mol Cell Biol 1997; 17:999-1009. [PMID: 9001253 PMCID: PMC231825 DOI: 10.1128/mcb.17.2.999] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Boundary elements are thought to define the peripheries of chromatin domains and to restrict enhancer-promoter interactions to their target genes within their domains. We previously characterized a cDNA encoding the BEAF-32A protein (32A), which binds with high affinity to the scs' boundary element from the Drosophila melanogaster 87A7 hsp70 locus. Here, we report a second protein, BEAF-32B, that differs from 32A only in its amino terminus. Unlike 32A, it has the same DNA binding specificity as the complete BEAF activity affinity purified from Drosophila. We characterize three domains in these proteins. Heterocomplex formation is mediated by their identical carboxy-terminal domains, and DNA binding is mediated by their unique amino-terminal domains. The identical middle domains of 32A and 32B are dispensable for the functions described here, although they may be important for boundary element function. 32A and 32B apparently form trimers, and the ratio of 32A to 32B varies at different loci on polytene chromosomes as judged by immunofluorescence. The scs' element contains a high- and low-affinity binding site for BEAF. We observed that interaction with the low-affinity site is facilitated by binding to the high-affinity site some 200 bp distant.
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Levang AK, Zhao K, Singh J. Effect of ethanol/propylene glycol on the in vitro percutaneous absorption of aspirin, biophysical changes and macroscopic barrier properties of the skin. Int J Pharm 1999; 181:255-63. [PMID: 10370221 DOI: 10.1016/s0378-5173(99)00055-1] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of the solvent systems ethanol (EtOH), propylene glycol (PG) and combinations thereof was examined on the in vitro percutaneous absorption of the antithrombotic, aspirin, through porcine epidermis. Biophysical changes in the stratum corneum lipids were studied through the use of Fourier transform infrared (FTIR) spectroscopy. Macroscopic barrier properties of the epidermis were examined through the use of in vitro transepidermal water loss (TEWL). The flux of aspirin increased with increasing concentrations of EtOH in the solvent systems. The maximum flux of aspirin was achieved by 80% EtOH in combination with 20% PG beyond which (i.e. 100% EtOH) there was no increase in the flux. FTIR spectroscopic study was enacted in order to determine the biophysical properties of the stratum corneum when the solvents were applied. The FTIR spectra of the stratum corneum treated with 80% EtOH/20% PG showed a maximum decrease in absorbance for the asymmetric and symmetric C&z. sbnd;H peaks, which suggests a greater loss of the lipids in the stratum corneum layers. In vitro TEWL studies allowed an investigation into the macroscopic barrier integrity properties of the stratum corneum. The TEWL results indicated that each of the solvent systems significantly enhanced (P<0.05) in vitro TEWL in comparison to the control. In conclusion, 80% EtOH/20% PG enhanced the percutaneous absorption of aspirin by perturbing the macroscopic barrier integrity of the stratum corneum and through a loss of stratum corneum lipids.
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Zhao K, Singh J. In vitro percutaneous absorption enhancement of propranolol hydrochloride through porcine epidermis by terpenes/ethanol. J Control Release 1999; 62:359-66. [PMID: 10528073 DOI: 10.1016/s0168-3659(99)00171-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The purpose of this study was to investigate the mechanism(s) of percutaneous absorption enhancement of propranolol hydrochloride (PHCL) across porcine epidermis by terpenes (e.g. menthone and limonene) in combination with ethanol. The in vitro percutaneous absorption experiments were performed using Franz diffusion cells. The solubility of PHCL in control and enhancer solutions was determined through high-performance liquid chromatography. Partitioning of PHCL to powdered SC from control or enhancer solutions was also determined in order to investigate the binding of PHCL to the SC from the SC/enhancer system. Fourier transform infrared spectroscopy (FT-IR) was employed to study the biophysical changes in stratum corneum (SC) lipids. The in vitro macroscopic barrier properties were investigated by measuring transepidermal water loss (TEWL) using Tewameter. Five percent menthone or limonene in combination with ethanol (EtOH) (menthone/EtOH or limonene/EtOH) significantly increased (P<0.05) the flux of PHCL through porcine epidermis in comparison to the control (EtOH). The partitioning of PHCL to the SC from the SC/enhancer system was also significantly greater than the SC/control system. The above enhancers showed a decrease in the peak heights and areas for both asymmetric and symmetric C-H stretching absorbances in comparison with the untreated SC, indicating the SC lipids extraction. Menthone/EtOH and limonene/EtOH enhanced (P<0.05) the in vitro TEWL through the epidermis in comparison to the control. Thus, an enhancement in the flux of PHCL by menthone/EtOH and limonene/EtOH is due to SC lipid extraction, macroscopic barrier perturbation, and improvement in the partitioning of the drug to the SC.
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Kurtz SM, Villarraga ML, Zhao K, Edidin AA. Static and fatigue mechanical behavior of bone cement with elevated barium sulfate content for treatment of vertebral compression fractures. Biomaterials 2005; 26:3699-712. [PMID: 15621260 DOI: 10.1016/j.biomaterials.2004.09.055] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 09/24/2004] [Indexed: 11/29/2022]
Abstract
The use of bone cement to treat vertebral compression fractures in a percutaneous manner requires placement of the cement under fluoroscopic image guidance. To enhance visualization of the flow during injection and to monitor and prevent leakage beyond the confines of the vertebral body, the orthopedic community has described increasing the amount of radiopacifier in the bone cement. In this study, static tensile and compressive testing, as well as fully reversed fatigue testing, was performed on three PMMA-based bone cements. Cements tested were SimplexP with 10% barium sulfate (Stryker Orthopedics, Mahwah, NJ) which served as a control; SimplexP with 36% barium sulfate prepared according to the clinical recommendation of Theodorou et al.; and KyphX HV-R with 30% barium sulfate (Kyphon Inc., Sunnyvale, CA). Static tensile and compressive testing was performed in accordance with ASTM F451-99a. Fatigue testing was conducted in accordance with ASTM F2118-01a under fully reversed, +/-10-, +/-15-, and +/-20-MPa stress ranges. Survival analysis was performed using three-parameter Weibull modeling techniques. KyphX HV-R was found to have comparable static mechanical properties and significantly greater fatigue life than either of the two control materials evaluated in the present study. The static tensile and compressive strengths for all three PMMA-based bone cements were found to be an order of magnitude greater than the expected stress levels within a treated vertebral body. The static and fatigue testing data collected in this study indicate that bone cement can be designed with barium sulfate levels sufficiently high to permit fluoroscopic visualization while retaining the overall mechanical profile of a conventional bone cement under typical in vivo loading conditions.
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Zhao K, Bai ZG, Bo A, Chi I. A systematic review and meta-analysis of music therapy for the older adults with depression. Int J Geriatr Psychiatry 2016; 31:1188-1198. [PMID: 27094452 DOI: 10.1002/gps.4494] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 12/12/2022]
Abstract
OBJECTIVES To determine the efficacy of music therapy in the management of depression in the elderly. METHOD We conducted a systematic review and meta-analysis of randomized controlled trials. Change in depressive symptoms was measured with various scales. Standardized mean differences were calculated for each therapy-control contrast. RESULTS A comprehensive search yielded 2,692 citations; 19 articles met inclusion criteria. Meta-analysis suggests that music therapy plus standard treatment has statistical significance in reducing depressive symptoms among older adults (standardized mean differences = 1.02; 95% CI = 0.87, 1.17). CONCLUSIONS This systematic review and meta-analysis suggests that music therapy has an effect on reducing depressive symptoms to some extent. However, high-quality trials evaluating the effects of music therapy on depression are required. Copyright © 2016 John Wiley & Sons, Ltd.
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Meta-Analysis |
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Zhao K, Singh J. Mechanisms of percutaneous absorption of tamoxifen by terpenes: eugenol, D-limonene and menthone. J Control Release 1998; 55:253-60. [PMID: 9795076 DOI: 10.1016/s0168-3659(98)00053-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The effect of chemical penetration enhancers (e.g., eugenol, d-limonene and menthone in combination with 50% ethanol) on the in vitro percutaneous absorption of tamoxifen through porcine epidermis has been investigated. The above enhancers significantly increased (p<0.05) the permeability coefficient of tamoxifen in comparison with the control (50% ethanol). Fourier transform infrared spectroscopy (FT-IR) was employed to investigate the biophysical changes in the stratum corneum (SC) lipids by the enhancer(s). FT-IR results showed that the treatment of the SC with enhancers did not produce a blue shift in the asymmetric and symmetric C-H stretching peak positions. However, all of the above enhancers showed a decrease in peak heights and areas for both asymmetric and symmetric C-H stretching absorbances in comparison with the untreated SC. A decrease in peak heights and areas is a measure of lipid extraction. Partitioning of tamoxifen to powdered SC from control and enhancer solutions was also determined. FT-IR and partitioning studies reveal that the enhancement in the permeability coefficient of tamoxifen by eugenol and d-limonene is due to lipid extraction and improvement in the partitioning of the drug to the SC. However, menthone enhanced the permeability of tamoxifen by increasing extraction of the SC lipids and not by improving the partitioning of the drug to the SC.
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Liu JM, Zhou Y, Li Y, Li T, Leng B, Zhang P, Liang G, Huang Q, Yang PF, Shi H, Zhang J, Wan J, He W, Liang C, Zhu G, Xu Y, Hong B, Yang X, Bai W, Tian Y, Zhang H, Li Z, Li Q, Zhao R, Fang Y, Zhao K. Parent Artery Reconstruction for Large or Giant Cerebral Aneurysms Using the Tubridge Flow Diverter: A Multicenter, Randomized, Controlled Clinical Trial (PARAT). AJNR Am J Neuroradiol 2018; 39:807-816. [PMID: 29599173 DOI: 10.3174/ajnr.a5619] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/26/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND PURPOSE Although flow diverters have been reported with favorable clinical and angiographic outcomes in various literatures, randomized trials determining their true effectiveness and safety are still in lack. The Parent Artery Reconstruction for Large or Giant Cerebral Aneurysms Using the Tubridge Flow Diverter (PARAT) trial was designed to evaluate the safety and efficacy of the Tubridge flow diverter in the treatment of large or giant aneurysms in comparison with Enterprise stent-assisted coiling. MATERIALS AND METHODS This prospective, multicenter, randomized trial was conducted at 12 hospitals throughout China. Enrolled adults with unruptured large/giant intracranial aneurysms were randomly assigned (1:1) to receive either Enterprise stent-assisted coiling or Tubridge flow diverter implantation. The primary end point was complete occlusion at 6-month follow-up, while secondary end points included technical success, mortality, target vessel-related stroke, aneurysm bleeding, in-stent stenosis, parent artery occlusion, and the frequency of all adverse events. RESULTS Among 185 enrolled subjects, 41 withdrew before procedure initiation. Overall, 82 subjects underwent Tubridge implantation, and 62 subjects were primarily treated with stent-assisted coiling. The results of 6-month follow-up imaging included complete occlusion rates of 75.34% versus 24.53% for the Tubridge and stent-assisted coiling groups, respectively, with a calculated common odds ratio of 9.4 (95% confidence interval, 4.14-21.38; P < .001). There was a higher, nonsignificant frequency of complications for Tubridge subjects. Multivariate analysis showed a decreased stroke rate at the primary investigational site, with a marginal P value (P = .051). CONCLUSIONS This trial showed an obviously higher rate of large and giant aneurysm obliteration with the Tubridge FD over Enterprise stent-assisted coiling. However, this higher obliteration rate came at the cost of a nonsignificantly higher rate of complications. Investigational site comparisons suggested that a learning curve for flow-diverter implantation should be recognized and factored into trial designs.
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Randomized Controlled Trial |
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Zhao K, Murray S, Davies DS, Boobis AR, Gooderham NJ. Metabolism of the food derived mutagen and carcinogen 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) by human liver microsomes. Carcinogenesis 1994; 15:1285-8. [PMID: 8020169 DOI: 10.1093/carcin/15.6.1285] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Animal studies have shown that 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) undergoes both activation to a genotoxic metabolite and detoxication, catalysed by CYP enzymes. In this study, using direct chemical analysis, we have examined PhIP metabolism by the microsomal fraction of human liver for comparison to that occurring in animals. PhIP was incubated with human liver microsomes in the presence of an NADPH regenerating system and the reaction mixture then analyzed by HPLC. Only one metabolite, identified as N-hydroxy PhIP, was produced. The N-hydroxylation of PhIP by human liver microsomal fraction obeyed Michaelis-Menten kinetics, with a Km of 55 microM and a Vmax of 666 pmol/min/mg protein. Furafylline, a potent and specific inhibitor of CYP1A2 in man, inhibited this reaction by > 95%, with an IC50 of 0.6 microM. PhIP inhibited high affinity phenacetin O-deethylase activity of human liver microsomes, an activity catalysed specifically by CYP1A2, with an IC50 of about 80 microM. These data indicate that, in human liver microsomes, N-hydroxylation is the only route of oxidative metabolism of PhIP, yielding a genotoxic species, and that this reaction is catalysed almost exclusively by CYP1A2. Furthermore, the exclusive oxidative activation of PhIP by human liver is in direct contrast to PhIP metabolism in rodents and non-human primates where oxidative detoxication products predominate.
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Zhao K, Chai X, Johnston K, Clements A, Marmorstein R. Crystal structure of the mouse p53 core DNA-binding domain at 2.7 A resolution. J Biol Chem 2001; 276:12120-7. [PMID: 11152481 DOI: 10.1074/jbc.m011644200] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The p53 tumor suppressor is a sequence-specific DNA-binding protein that activates transcription in response to DNA damage to promote cell cycle arrest or apoptosis. The p53 protein functions in a tetrameric form in vivo and contains four domains including an N-terminal transcriptional activation domain, a C-terminal regulatory domain, a tetramerization domain, and a central core DNA-binding domain that is the site of the majority of tumor-derived mutations. Here we report the 2.7-A crystal structure of the mouse p53 core domain. Like the human p53 core domain in complex with DNA, the mouse p53 core domain adopts an immunoglobulin-like beta sandwich architecture with a series of loops and short helices at opposite ends of the beta sandwich. Comparison of the DNA-bound and DNA-free p53 core domains reveals that while the central beta sandwich architecture remains largely unchanged, a loop region important for DNA binding undergoes significant rearrangement. Although this loop region mediates major groove DNA contacts in the DNA-bound structure, it adopts a conformation that is incompatible with DNA binding in the DNA-free structure. Interestingly, crystals of the DNA-free core domain contain a noncrystallographic trimer with three nearly identical subunit-subunit (dimer) contacts. These dimer contacts align the p53 core domains in a way that is incompatible with simultaneous DNA binding by both protomers of the dimer. Surprisingly, similar dimer contacts are observed in crystals of the human p53 core domain with DNA in which only one of the three p53 protomers in the asymmetric unit cell is specifically bound to DNA. We propose that the p53 core domain dimer that is seen in the crystals described here represents a physiologically relevant inactive form of p53 that must undergo structural rearrangement for sequence-specific DNA binding.
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Oldreive C, Zhao K, Paganga G, Halliwell B, Rice-Evans C. Inhibition of nitrous acid-dependent tyrosine nitration and DNA base deamination by flavonoids and other phenolic compounds. Chem Res Toxicol 1998; 11:1574-9. [PMID: 9860503 DOI: 10.1021/tx980163p] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Exposure of tyrosine or DNA bases to acidic nitrite at low pH results in the nitration of tyrosine and the formation of base deamination products, respectively. At pH 1, hypoxanthine and xanthine are formed from the deamination of adenine and guanine, respectively, whereas under the same conditions, uracil is not detected. The yield of 3-nitrotyrosine derived from interaction of equimolar nitrite and tyrosine at pH 1 is approximately 50% of that obtained from equimolar peroxynitrite-tyrosine interactions at pH 7. 4. The ability of a range of plant phenolic constituents to prevent damage mediated by acidic nitrite was also examined in comparison with the activity of vitamin C. The epicatechin/gallate family of flavonols, constituents of green tea, red wine, etc., demonstrates the most extensive inhibitory properties against both tyrosine nitration and base deamination. The results also show that ascorbic acid is a poor inhibitor of nitration or deamination under acidic conditions such as those of the stomach. The ability of plant phenolics to scavenge reactive nitrogen species derived from acidic nitrite may contribute to the protective effects of tea polyphenols against gastric cancer.
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Abstract
Nine commercial brands of grapefruit juice were analyzed for their flavonoid content by HPLC to determine if significant brand-to-brand variance in grapefruit juice flavonoid content exists. Flavonoid glycosides narirutin, naringin, hesperidin, neohesperidin, didymin, and poncirin have been identified in all the grapefruit juices examined. The aglycone quercetin was detected in only two brands. All the juices were free from methoxylated flavonoid aglycones. There was a significant difference in the amounts of total flavonoids and individual flavonoids in the nine brands. The concentration of total flavonoids ranged between 19.44 and 84.28 mg/100 ml juice. Naringin was found to be the major flavonoid followed by narirutin and hesperidin. Their concentrations ranged from 14.56 to 63.8; 2.25 to 12.20; and 0.24 to 3.12 mg/100 ml juice, respectively.
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Morgan RW, Kelsh MA, Zhao K, Exuzides KA, Heringer S, Negrete W. Radiofrequency exposure and mortality from cancer of the brain and lymphatic/hematopoietic systems. Epidemiology 2000; 11:118-27. [PMID: 11021607 DOI: 10.1097/00001648-200003000-00007] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The proliferation of wireless communication technologies has raised public concern regarding potential health effects of radiofrequency (RF) exposures. This is the first report of findings from a large-cohort mortality study among employees of Motorola, a manufacturer of wireless communication products. We examined all major causes of mortality, with brain cancers, lymphomas, and leukemias as a priori outcomes of interest. Using job titles, we classified workers into high, moderate, low, and background RF exposure groups. A total of 195,775 workers contributed 2.7 million person-years during the 1976-1996 period. Using external comparisons, the standardized mortality ratios for RF-exposed workers were 0.53 [95% confidence interval (CI) = 0.21-1.09] and 0.54 (95% CI = 0.33-0.83) for central nervous system/brain cancers and all lymphomas/leukemias. Rate ratios calculated from Poisson regression models based on internal comparisons were near 1.0 for brain cancers and below 1.0 for all lymphomas and leukemias. These findings were consistent across cumulative, peak, and usual exposure classifications. We did not observe higher risk with increased exposure duration or latency. Although this study is limited by the use of a qualitative exposure matrix and the relatively young age of the cohort, our findings do not support an association between occupational RF exposure and brain cancers or lymphoma/leukemia.
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Wang Q, Chen Q, Zhao K, Wang L, Wang L, Traboulsi EI. Update on the molecular genetics of retinitis pigmentosa. Ophthalmic Genet 2001; 22:133-54. [PMID: 11559856 DOI: 10.1076/opge.22.3.133.2224] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of retinal dystrophies characterized by photoreceptor cell degeneration. RP causes night blindness, a gradual loss of peripheral visual fields, and eventual loss of central vision. Advances in molecular genetics have provided new insights into the genes responsible and the pathogenic mechanisms of RP. The genetics of RP is complex, and the disease can be inherited in autosomal dominant, recessive, X-linked, or digenic modes. Twenty-six causative genes have been identified or cloned for RP, and an additional fourteen genes have been mapped, but not yet identified. Eight autosomal dominant forms are due to mutations in RHO on chromosome 3q21-24, RDS on 6p21.1-cen, RP1 on 8p11-21, RGR on 10q23, ROM1 on 11q13, NRL on 14q11.1-11.2, CRX on 19q13.3, and PRKCG on 19q13.4. Autosomal recessive genes include RPE65 on chromosome 1p31, ABCA4 on 1p21-13, CRB1 on 1q31-32.1, USH2A on 1q41, MERTK on 2q14.1, SAG on 2q37.1, RHO on 3q21-24, PDE6B on 4p16.3, CNGA1 on 4p14-q13, PDE6A on 5q31.2-34, TULP1 on 6p21.3, RGR on 10q, NR2E3 on 15q23, and RLBP1 on 15q26. For X-linked RP, two genes, RP2 and RP3 (RPGR), have been cloned. Moreover, heterozygous mutations in ROM1 on 11q13, in combination with heterozygous mutations in RDS on 6p21.1-cen, cause digenic RP (the two-locus mechanism). These exciting molecular discoveries have defined the genetic pathways underlying the pathogenesis of retinitis pigmentosa, and have raised the hope of genetic testing for RP and the development of new avenues for therapy.
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Wang SQ, Du QS, Zhao K, Li AX, Wei DQ, Chou KC. Virtual screening for finding natural inhibitor against cathepsin-L for SARS therapy. Amino Acids 2006; 33:129-35. [PMID: 16998715 PMCID: PMC7087620 DOI: 10.1007/s00726-006-0403-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Accepted: 08/08/2006] [Indexed: 11/30/2022]
Abstract
Recently Simmons et al. reported a new mechanism for SARS virus entry into target cells, where MDL28170 was identified as an efficient inhibitor of CTSL-meditated substrate cleavage with IC50 of 2.5 nmol/l. Based on the molecule fingerprint searching method, 11 natural molecules were found in the Traditional Chinese Medicines Database (TCMD). Molecular simulation indicates that the MOL376 (a compound derived from a Chinese medicine herb with the therapeutic efficacy on the human body such as relieving cough, removing the phlegm, and relieving asthma) has not only the highest binding energy with the receptor but also the good match in geometric conformation. It was observed through docking studies that the van der Waals interactions made substantial contributions to the affinity, and that the receptor active pocket was too large for MDL21870 but more suitable for MOL736. Accordingly, MOL736 might possibly become a promising lead compound for CTSL inhibition for SARS therapy.
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Research Support, Non-U.S. Gov't |
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