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Wei K, Wang L, Gu L, Liu Q, Li W, Zhou Z, Han W, Ouyang C, Zhang R, Huang X, Zhang X. 2D-Like Catalyst with a Micro-nanolinked Functional Surface for Water Purification. Environ Sci Technol 2024; 58:3007-3018. [PMID: 38294954 DOI: 10.1021/acs.est.3c07536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
In water purification, the performance of heterogeneous advanced oxidation processes significantly relies upon the utilization of the catalyst's specific surface area (SSA). However, the presence of the structural "dead volume" and pore-size-induced diffusion-reaction trade-off limitation restricts the functioning of the SSA. Here, we reported an effective approach to make the best SSA by changing the traditional 3D spherule catalyst into a 2D-like form and creating an in situ micro-nanolinked structure. Thus, a 2D-like catalyst was obtained which was characterized by a mini "paddy field" surface, and it exhibited a sharply decreased dead volume, a highly available SSA and oriented flexibility. Given its paddy-field-like mass-transfer routine, the organic capture capability was 7.5-fold higher than that of the catalyst with mesopores only. Moreover, such a catalyst exhibited a record-high O3-to-·OH transition rate of 2.86 × 10-8 compared with reported millimetric catalysts (metal base), which contributed to a 6.12-fold higher total organic removal per catalyst mass than traditional 3D catalysts. The facile scale preparation, performance stability, and significant material savings with the 2D-like catalyst were also beneficial for practical applications. Our findings provide a unique and general approach for designing potential catalysts with excellent performance in water purification.
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Affiliation(s)
- Kajia Wei
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Lu Wang
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Liankai Gu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Qiqing Liu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Wei Li
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Zuoyong Zhou
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Weiqing Han
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
| | - Changpei Ouyang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Rufan Zhang
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
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Ren T, Ouyang C, Zhou Z, Chen S, Yin M, Huang X, Zhang X. Mn-doped carbon-Al 2SiO 5 fibers enable catalytic ozonation for wastewater treatment: Interface modulation and mass transfer enhancement. J Hazard Mater 2023; 460:132307. [PMID: 37647666 DOI: 10.1016/j.jhazmat.2023.132307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 08/09/2023] [Accepted: 08/13/2023] [Indexed: 09/01/2023]
Abstract
Heterogeneous catalytic ozonation is an efficient approach to remove hazardous and refractory organic contaminants in wastewater. It is crucial to design an ozone catalyst with high catalytic activity, high mass transfer and facile separation properties. Herein, easily separable aluminosilicate (Al2SiO5) fibers were developed as carriers and after interface modulation, Mn-doped carbon-Al2SiO5 (Mn-CAS) fibrous catalysts were proposed for catalytic ozonation. The growth of carbon shells on Al2SiO5 fiber surface and the introduction of metal Mn provided abundant Lewis acid sites to catalyze ozone. The Mn-CAS fiber/O3 system exhibited superior reactivity to degrade oxalic acid with a rate constant of 0.034 min-1, which was about 19 times as high as Al2SiO5/O3. For coal gasification wastewater treatment, Mn-CAS fibers also demonstrated high catalytic activity and stability and the COD removal was over 56%. Computational fluid dynamic simulations proved the high mass transfer properties of fibrous catalysts. Hydroxyl radicals (•OH) were identified as the predominant active species for organic degradation. Particularly, the catalytic pathways of O3 to •OH on Mn-O4 sites were revealed by theoretical calculations. This work provides a novel fibrous catalyst with high reactivity and mass transfer as well as easy separation characteristics for catalytic ozonation and wastewater purification.
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Affiliation(s)
- Tengfei Ren
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Changpei Ouyang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Zuoyong Zhou
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Shuning Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Mengxi Yin
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
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Ren T, Yin M, Chen S, Ouyang C, Huang X, Zhang X. Single-Atom Fe-N 4 Sites for Catalytic Ozonation to Selectively Induce a Nonradical Pathway toward Wastewater Purification. Environ Sci Technol 2023; 57:3623-3633. [PMID: 36790324 DOI: 10.1021/acs.est.2c07653] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Nonradical oxidation has been determined to be a promising pathway for the degradation of organic pollutants in heterogeneous catalytic ozonation (HCO). However, the bottlenecks are the rational design of catalysts to selectively induce nonradicals and the interpretation of detailed nonradical generation mechanisms. Herein, we propose a new HCO process based on single-atom iron catalysts, in which Fe-N4 sites anchored on the carbon skeleton exhibited outstanding catalytic ozonation activity and stability for the degradation of oxalic acid (OA) and p-hydroxybenzoic acid (pHBA) as well as the advanced treatment of a landfill leachate secondary effluent. Unlike traditional radical oxidation, nonradical pathways based on surface-adsorbed atomic oxygen (*Oad) and singlet oxygen (1O2) were identified. A substrate-dependent behavior was also observed. OA was adsorbed on the catalyst surface and mainly degraded by *Oad, while pHBA was mostly removed by O3 and 1O2 in the bulk solution. Density functional theory calculations and molecular dynamics simulations revealed that one terminal oxygen atom of ozone preferred bonding with the central iron atom of Fe-N4, subsequently inducing the cleavage of the O-O bond near the catalyst surface to produce *Oad and 1O2. These findings highlight the structural design of an ozone catalyst and an atomic-level understanding of the nonradical HCO process.
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Affiliation(s)
- Tengfei Ren
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
| | - Mengxi Yin
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shuning Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
| | - Changpei Ouyang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, People's Republic of China
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Li F, Zeng M, Ouyang C, Liu J, Ning S, Cui H, Yuan Y, Su Z, Zhou J, Liu W, Wang L, Wang X, Xing C, Qin L, Wang N. WCN23-0614 HUMAN AMNION-DERIVED MESENCHYMAL STEM CELL TREATMENT FOR A MALE UREMIC CALCIPHYLAXIS PATIENT WITH MULTISYSTEM ANGIOPATHY. Kidney Int Rep 2023. [DOI: 10.1016/j.ekir.2023.02.486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2023] Open
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Ajewole C, Bestoyong D, Ouyang C, Feranec J, Lamvu G, Carrillo J. Chronic Pelvic Pain: A Guide to Perform a Focused Physical Exam. J Minim Invasive Gynecol 2022. [DOI: 10.1016/j.jmig.2022.09.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ajewole C, Carrillo J, Ouyang C, Lamvu G. 8355 Transvaginal Photobiomodulation for Treatment of Pelvic Pain Associated with Endometriosis: A Report from Clinical Settings. J Minim Invasive Gynecol 2022. [DOI: 10.1016/j.jmig.2022.09.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ouyang C, Wei K, Huang X, Gamal El-Din M, Zhang X. Bifunctional Fe for Induced Graphitization and Catalytic Ozonation Based on a Fe/N-Doped Carbon-Al 2O 3 Framework: Theoretical Calculations Guided Catalyst Design and Optimization. Environ Sci Technol 2021; 55:11236-11244. [PMID: 34270217 DOI: 10.1021/acs.est.1c00728] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Heterogeneous catalytic ozonation is regarded as a feasible technology in advanced wastewater treatment. Catalytic performance, mass transfer, and mechanical strength are the key elements for large-scale applications of catalysts. To optimize those elements, Fe was selected for its dual role in graphitization and catalytic ozonation. A Fe/N-doped micron-scale carbon-Al2O3 framework (CAF) was designed and applied to a fluidized catalytic process for the treatment of secondary effluent from coal gasification. The chemical oxygen demand removal rate constant and the hydroxyl radical generation efficiency (Rct) of the Fe/N-doped CAF were 190% and 429% higher than those of pure ozone, respectively. Theoretical calculations revealed that higher Fe valence promoted ozone decomposition, which implied increasing FeIII content for further catalyst optimization. The rate constant and Rct with a higher FeIII-proportion catalyst were increased by 13% and 16%, respectively, compared to those with the lower one. Molecular dynamics and density functional theory calculations were performed to analyze the reaction kinetics qualitatively and quantitatively. The energy barrier corresponding to FeIII configuration was 1.32 kcal mol-1, 27% lower than that for FeII configuration. These theoretical calculations guided the catalyst optimization and provided a novel solution for designing ozonation catalysts. The Fe/N-doped CAF demonstrated a great potential for practical applications.
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Affiliation(s)
- Changpei Ouyang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Kajia Wei
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210095, China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
- International Joint Laboratory on Low Carbon Clean Energy Innovation, Tsinghua University, Beijing 100084, China
| | - Mohamed Gamal El-Din
- Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
- International Joint Laboratory on Low Carbon Clean Energy Innovation, Tsinghua University, Beijing 100084, China
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Wei K, Wang Z, Ouyang C, Cao X, Liang P, Huang X, Zhang X. A hybrid fluidized-bed reactor (HFBR) based on arrayed ceramic membranes (ACMs) coupled with powdered activated carbon (PAC) for efficient catalytic ozonation: A comprehensive study on a pilot scale. Water Res 2020; 173:115536. [PMID: 32032886 DOI: 10.1016/j.watres.2020.115536] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 12/16/2019] [Accepted: 01/21/2020] [Indexed: 06/10/2023]
Abstract
Taking advantage of the high mass transfer in the bulk solution of fluidized-bed reactor (FBR), and the benefits of simultaneous particle separation and ozone catalysis on ceramic membranes, we proposed a hybrid fluidized-bed reactor (HFBR) based on arrayed ceramic membranes (ACMs) coupled with powdered activated carbon (PAC) for efficient catalytic ozonation. The optimum HFBR performance on a pilot scale was found at PAC addition of 3 g/L, ozone dosage of 25 mg/L, hydraulic retention time of 60 min and auxiliary aeration strength of 5 m3/h. During the 30-day treatment of coal-gasification secondary effluent (200 L/h), the HFBR system revealed not only a 117% increase in ozone utilization efficiency (ΔCOD/ΔO3) upon pure ozonation but also a highly purified effluent with better sterilization and low residual bromate (∼11 μg/L). Low-molecular-weight organic fragments and acids, as well as phthalate esters were identified as the main products in this process. By density functional theory (DFT) calculations, it was found the main functional groups (carbonyls, -C=O) on the PAC could be protected from direct ozonation in the presence of ozone-degradable organics (e.g. phenolic and aliphatic compounds) in the wastewater through an ozone-competing reaction, which prevented the rapid inactivation of the PAC in catalytic ozonation. A longer service life and cheaper materials for ceramic membranes would benefit low operation costs for the HFBR. Moreover, the addition of PAC could greatly reduce ozone demand by ∼60% in the HFBR, and therefore decrease energy consumption by ∼30%. Hence, the HFBR was proved to be a highly competitive technology for wide application in the near future.
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Affiliation(s)
- Kajia Wei
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Zhuo Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Changpei Ouyang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xiaoxin Cao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Peng Liang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xia Huang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
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Schrock AB, Ouyang C, Sandhu J, Sokol E, Jin D, Ross JS, Miller VA, Lim D, Amanam I, Chao J, Catenacci D, Cho M, Braiteh F, Klempner SJ, Ali SM, Fakih M. Tumor mutational burden is predictive of response to immune checkpoint inhibitors in MSI-high metastatic colorectal cancer. Ann Oncol 2019; 30:1096-1103. [PMID: 31038663 DOI: 10.1093/annonc/mdz134] [Citation(s) in RCA: 382] [Impact Index Per Article: 76.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Microsatellite instability (MSI) is a biomarker for response to immune checkpoint inhibitors (ICPIs). PD-1 inhibitors in metastatic colorectal carcinoma (mCRC) with MSI-high (MSI-H) have demonstrated a high disease control rate and favorable progression-free survival (PFS); however, reported response rates to pembrolizumab and nivolumab are variable and often <50%, suggesting that additional predictive biomarkers are needed. METHODS Clinicopathologic data were collected from patients with MSI-H mCRC confirmed by hybrid capture-based next-generation sequencing (NGS) treated with PD-1/L1 inhibitors at five institutes. Tumor mutational burden (TMB) was determined on 0.8-1.1 Mb of sequenced DNA and reported as mutations/Mb. Potential biomarkers of response and time to progression were analyzed by univariate and multivariate analyses. Once TMB was confirmed as a predictive biomarker, a larger dataset of 18 140 unique CRC patients was analyzed to define the relevance of the identified TMB cut-point. RESULTS A total of 22 patients were treated with PD-1/L1 inhibitors including 19 with pembrolizumab monotherapy. Among tested variables, TMB showed the strongest association with objective response (OR; P < 0.001) and PFS, by univariate (P < 0.001) and multivariate analysis (P < 0.01). Using log-rank statistics, the optimal predictive cut-point for TMB was estimated between 37 and 41 mutations/Mb. All 13 TMBhigh cases responded, while 6/9 TMBlow cases had progressive disease. The median PFS for TMBhigh has not been reached (median follow-up >18 months) while the median PFS for TMBlow was 2 months. A TMB of 37.4 mutations/Mb in a large MSI-H mCRC population (821/18, 140 cases; 4.5%) evaluated by NGS corresponded to the 35th percentile cut-point. CONCLUSIONS TMB appears to be an important independent biomarker within MSI-H mCRC to stratify patients for likelihood of response to ICPIs. If validated in prospective studies, TMB may play an important role in guiding the sequencing and/or combinations of ICPIs in MSI-H mCRC.
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Affiliation(s)
| | - C Ouyang
- Center for Informatics, City of Hope National Medical Center, Duarte; Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte
| | - J Sandhu
- Department of Medical Oncology and Therapeutics Research, City of Hope Comprehensive Cancer Center, Duarte
| | - E Sokol
- Foundation Medicine, Inc., Cambridge
| | - D Jin
- Foundation Medicine, Inc., Cambridge
| | - J S Ross
- Foundation Medicine, Inc., Cambridge; Department of Pathology, SUNY Upstate Medical University, Syracuse
| | | | - D Lim
- Department of Medical Oncology and Therapeutics Research, City of Hope Comprehensive Cancer Center, Duarte
| | - I Amanam
- Department of Medical Oncology and Therapeutics Research, City of Hope Comprehensive Cancer Center, Duarte
| | - J Chao
- Department of Medical Oncology and Therapeutics Research, City of Hope Comprehensive Cancer Center, Duarte
| | - D Catenacci
- Section of Hematology/Oncology, Department of Medicine, University of Chicago Medical Center and Biological Sciences, Chicago
| | - M Cho
- Division of Hematology and Oncology, Department of Internal Medicine, UC Davis Comprehensive Cancer Center, Sacramento
| | - F Braiteh
- Department of Hematology/Oncology, Comprehensive Cancer Centers of Nevada, Las Vegas
| | - S J Klempner
- The Angeles Clinic and Research Institute, Los Angeles, USA
| | - S M Ali
- Foundation Medicine, Inc., Cambridge
| | - M Fakih
- Department of Medical Oncology and Therapeutics Research, City of Hope Comprehensive Cancer Center, Duarte.
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Fakih M, Ouyang C, Wang C, Tu T, Cho M, Sy M, Longmate J, Lee P. High PD-L1 expression and high CD8+ T-cell infiltration identifies a new subpopulation of colorectal cancer with high risk of relapse and poor outcome. Ann Oncol 2017. [DOI: 10.1093/annonc/mdx393.084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Wu QN, Ling YZ, Ouyang C, Xie LJ, Huang T. [Effect of a new ROCK inhibitor thiazovivin on the morphology and function of human corneal endothelial cells]. Zhonghua Yan Ke Za Zhi 2016; 52:686-692. [PMID: 27647250 DOI: 10.3760/cma.j.issn.0412-4081.2016.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To evaluate the effect of thiazovivin, a novel ROCK inhibitor, on the morphology and function of human corneal endothelial cells(HCECs). METHODS The primary HCECs were identified by light microscopy and immunofluorescence staining of neuron-specific enolase. To screen the optimal concentration and action time of thiazovivin for maintaining the morphology and function of primary HCECs, Na (+)/K (+)-ATPase and N-cadherin were chosen as indicators, and the morphology and function of HCECs in various concentrations(0 μmol/L, 2 μmol/L, 4 μmol/L, and 6 μmol/L)for different durations(24 h and 48 h)were examined by immunofluorescence experiments. The effect of thiazovivin on the expression of ROCK was investigated by immunofluorescence and Western blot. RESULTS The primary HCECs cultured were hexagonal, closely packed, homogeneously and obviously stained by neuron-specific enolase. The immunofluorescence staining of Na(+)/K(+)-ATPase showed that when the primary HCECs cultured with various concentrations of thiazovivin(0, 2, 4, 6 μmol/L)for 24 h, the fluorescence were obvious, and the average absorbance values(A)were 1.27±0.08, 3.72±0.17, 21.07±4.67, 3.69±0.34, respectively. And the immunofluorescence staining of N-cadherin revealed that when the primary HCECs treated with 4 μmol/L thiazovivin for 24 h, the cell boundary was clear and the structure of the cells was intact. While the treating time of thiazovivin(4 μmol/L)on HCECs extended to 48 h, the immunofluorescence staining of Na(+)/K(+)-ATPase and N-cadherin showed that compared to HCECs treated with thiazovivin(4 μmol/L)for 24 h, the fluorescence intensity did not change significantly, but the cells arranged slightly untidy. In addition, the immunofluorescence staining of ROCK was weakened and the expression of ROCK was reduced by thiazovivin. Thiazovivin was effective for protecting the morphology and function of HCECs. An optimal improvement in the morphology, connection and function of HCECs was found when the primary HCECs were cultured with 4 μmol/L thiazovivin for 24 h. Moreover, the expression of ROCK protein could be significantly inhibited by thiazovivin. (Chin J Ophthalmol, 2016, 52: 686-692).
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Affiliation(s)
- Q N Wu
- Department of ophthalmology, Sun Yat-sen University, Zhongshan Ophthalmic Centre, Guangzhou 510060, China
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Baudoin F, Nualart E, Ouyang C, Tindel S. On probability laws of solutions to differential systems driven by a fractional Brownian motion. ANN PROBAB 2016. [DOI: 10.1214/15-aop1028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Zhang LN, Yang G, Cheng C, Shen C, Cui YY, Zhang J, Zhang JJ, Shen ZX, Zeng M, Ge YF, Sun B, Yu XB, Ouyang C, Zhang B, Mao HJ, Liu J, Xing CY, Zha XM, Wang NN. Plasma FGF23 levels and heart rate variability in patients with stage 5 CKD. Osteoporos Int 2015; 26:395-405. [PMID: 25224292 DOI: 10.1007/s00198-014-2862-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/14/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED Fibroblast growth factor 23(FGF23) is a bone-derived hormone which regulates mineral homeostasis but may also have a role in cardiovascular disease. Here, we found that higher plasma FGF23 was independently associated with decreased heart rate variability in stage 5 CKD patients and parathyroidectomy may reverse these abnormal indicators. INTRODUCTION Lower heart rate variability (HRV) in patients with chronic kidney disease (CKD) compared with healthy controls is associated with increased risk of cardiovascular disease (CVD). Higher levels of plasma FGF23 also predict higher risk of CVD. Here, we aimed to evaluate the relationship between plasma FGF23 levels and HRV in patients with stage 5 CKD and to investigate longitudinal changes of them together with the correlation between their changes in two severe secondary hyperparathyroidism (SHPT) subgroups with successful parathyroidectomy (PTX) and persistent SHPT. METHODS This cross-sectional study included 100 stage 5 CKD patients, 78 controls, and a prospective study in two PTX subgroups classified as successful PTX (n = 24) and persistent SHPT (n = 4) follow-up. Blood examination and 24-h Holter monitoring for HRV were measured. RESULTS Most HRV indices were lower in stage 5 CKD patients than in healthy controls, and plasma FGF23 levels were higher. In multivariate stepwise regression models, levels of plasma FGF23 and serum parathyroid hormone (PTH) were correlated with HRV. The successful PTX subgroup had significant improvements over baseline in HRV indices. Persistent SHPT subgroup had numerically similar changes in HRV indices. However, plasma FGF23 levels decreased in both subgroups. CONCLUSIONS Plasma FGF23 levels were higher in CKD patients than in controls, much higher in patients with severe SHPT. FGF23 was independently associated with decreased HRV in stage 5 CKD. Successful PTX may reverse these abnormal indicators and contribute to decreases in the risk of cardiovascular disease.
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Affiliation(s)
- L-N Zhang
- Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, Jiangsu Province, People's Republic of China
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Frimer M, Levano K, Rodriguez-Gabin A, Ouyang C, Cai J, Wang Y, Einstein M, Goldberg G, Horwitz S, Hou J. Exome sequencing identifies germline mutations involving novel single nucleotide polymorphisms within DNA repair pathway genes in uterine serous carcinoma. Gynecol Oncol 2014. [DOI: 10.1016/j.ygyno.2014.03.212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ouyang C, Frimer M, Wang Y, Hou L, Kuo D, Goldberg G, Hou J. Malignant endometrial polyps in uterine serous carcinoma: Does size matter? Gynecol Oncol 2014. [DOI: 10.1016/j.ygyno.2014.03.201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Tsuchiya K, Shiohira S, Sugiura H, Suzuki M, Okano K, Nitta K, Kaesler N, Immendorf S, Ouyang C, Carmeliet P, Floege J, Kruger T, Schlieper G, Georgescu A, Kalucka J, Olbrich S, Baumgartl J, Hackenbeck T, Eckardt KU, Weidemann A, Chmielewski S, Olejnik A, Sikorski K, Heemann U, Wesoly J, Bluyssen H, Baumann M, Mekahli D, Decuypere JP, Missiaen L, Levtchenko E, De Smedt H, Stasi A, Castellano G, Gigante M, Intini A, Pontrelli P, Divella C, Curci C, Grandaliano G, Gesualdo L, Vizza D, Perri A, Lofaro D, Toteda P, Lupinacci S, Leone F, Gigliotti P, Papalia T, Bonofiglio R, Vatazin AV, Astakhov PV, Zulkarnaev AB, Parodi E, Verzola D, D'Amato E, Viazzi F, Gonnella A, Garneri D, Pontremoli R, Garibotto G, Chen TH, Chen CH, Chen YC, Sue YM, Cheng CY, Guiying L, Ying L, Pozzoli S, Lino M, Delli Carpini S, Ferrandi M, Zerbini G, Simonini M, Zagato L, Molinari I, Citterio L, Manunta P, Feng X, Pan X, Wang W, Chen N, Chen YX, Wang WM, Chen N, Tanaka S, Yano S, Sugimoto T, Noh H, Yu MR, Kim HJ, Woo SA, Cho YJ, Kwon SH, Jeon JS, Han DC, Shimizu H, Yisireyili M, Nishijima F, Niwa T, Koh ES, Chung S, Kim SJ, Kim SJ, Yoon HE, Park CW, Chang YS, Shin SJ, Seong EY, Rhee H, Shin MJ, Yang BY, Jung YS, Lee DW, Lee SB, Kwak IS, Kim IY, Sancho-Martinez SM, Prieto-Garcia L, Lopez-Hernandez FJ, Lopez-Novoa JM, Bae EH, Choi HS, Joo SY, Kim IJ, Kim CS, Choi JS, Ma SK, Lee J, Kim SW, Humanes B, Sonia C, Jado J, Mojena M, Lara J, Alvarez-Sala L, Tejedor A, Lazaro A, Wada Y, Iyoda M, Matsumoto K, Shindo-Hirai Y, Kuno Y, Yamamoto Y, Suzuki T, Shibata T, Akizawa T, Lee DW, Kwak IS, Lee SB, Seong EY, Faubel S, Edelstein CL, Cano Penalver JL, de Frutos Garcia S, Griera Merino M, Luengo Rodriguez A, Garcia Jerez A, Bohorquez Magro L, Medrano D, Calleros Basilio L, Rodriguez Puyol M, Prieto-Garcia L, Sancho-Martinez SM, Lopez-Hernandez FJ, Lopez-Novoa JM, Thilo F, Liu Y, Tepel M, Hsu HH, Chen KH, Hung CC, Yang CW, Endlich N, Lin JL, Pavenstadt H, Rodrigues Diez RR, Mezzano S, Ruiz-Ortega M, Rodrigues Diez R, Lavoz C, Nakayama Y, Fukami K, Yamagishi SI, Obara N, Yokoro M, Ando R, Kaida Y, Toyonaga M, Kaifu K, Takeuchi M, Ueda S, Okuda S, Daenen K, Hoylaerts MF, Bammens B, Liu J, Zhong F, Dai Q, Xu L, Wang W, Chen N, Zaravinos A, Deltas CC. Cell signalling. Nephrol Dial Transplant 2013. [DOI: 10.1093/ndt/gft125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sun L, Ouyang C, Kou S, Wang S, Yao Y, Peng T, Xu Y, Tang L, Chen F. Cloning and Characterization of a cDNA Encoding Type 1 Diacylglycerol Acyltransferase from Sunflower (Helianthus annuus L.). Z NATURFORSCH C 2011. [DOI: 10.5560/znc.2011.66c0063] [Citation(s) in RCA: 5] [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: 11/24/2022]
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Cai F, Li C, Wu J, Min Q, Ouyang C, Zheng M, Ma S, Yu W, Lin F. Modulation of the oxidative stress and nuclear factor kappaB activation by theaflavin 3,3'-gallate in the rats exposed to cerebral ischemia-reperfusion. Folia Biol (Praha) 2007; 53:164-172. [PMID: 17976306] [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: 05/25/2023]
Abstract
The major pathobiological mechanisms of IR injury include excitotoxicity, oxidative stress, and inflammation. TF3, a major constituent of black tea, possesses biological functions such as anti-oxidative and anti-inflammatory activities. The purpose of this study was to verify the neuronal protective potential of TF3 and its mechanisms against cerebral IR injury in rats. TF3 administration (10 and 20 mg.kg-1) ameliorated the infarct volume. TF3 also decreased the content of MDA and NO. TF3 significantly increased the activity of SOD and GSH-Px, which were reduced by IR injury. Administration of TF3 decreased mRNA and protein expression of COX-2 and iNOS. DNA binding and Western blotting revealed an increase in NF-kappaB activation and IkappaB depletion in IR brain tissue. Pretreatment with TF3 markedly inhibited IRinduced increase in nuclear localization of NF-kappaB, and preserved IkappaB in the cytoplasm. The results show that TF3 exerts protective effects against cerebral IR injury by reducing oxidative stress and modulating the NF-kappaB activation.
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Affiliation(s)
- F Cai
- Department of Pharmacology, Medical College, Xianning University, Xianning, People's Republic of China
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Huang G, Peng S, Ouyang C, Huang K. [Spectrometric determination of nutritional elements in the medicine-food flowers]. Guang Pu Xue Yu Guang Pu Fen Xi 2000; 20:376-378. [PMID: 12958962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A study was carried out on the contents of nutritional elements in some medicine-food flowers by atomic absorption spectrometry. The results showed that flowers contain much more contents Fe, Ca, Mg and Co. The range of the average recovery in this method is 94%-108%, which indicate that the method we used is practicable. And flower is a kind of typical food source of containing high content of K and low content of Na. It is worth much more comprehensive utilization.
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Affiliation(s)
- G Huang
- Department of Food Science, Nanchang University, 330047 Nanchang
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Ouyang C, Martinez MJ, Young LS, Sprague KU. TATA-Binding protein-TATA interaction is a key determinant of differential transcription of silkworm constitutive and silk gland-specific tRNA(Ala) genes. Mol Cell Biol 2000; 20:1329-43. [PMID: 10648619 PMCID: PMC85276 DOI: 10.1128/mcb.20.4.1329-1343.2000] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [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: 11/20/2022] Open
Abstract
We have investigated the contribution of specific TATA-binding protein (TBP)-TATA interactions to the promoter activity of a constitutively expressed silkworm tRNA(C)(Ala) gene and have also asked whether the lack of similar interactions accounts for the low promoter activity of a silk gland-specific tRNA(SG)(Ala) gene. We compared TBP binding, TFIIIB-promoter complex stability (measured by heparin resistance), and in vitro transcriptional activity in a series of mutant tRNA(C)(Ala) promoters and found that specific TBP-TATA contacts are important for TFIIIB-promoter interaction and for transcriptional activity. Although the wild-type tRNA(C)(Ala) promoter contains two functional TBP binding sequences that overlap, the tRNA(SG)(Ala) promoter lacks any TBP binding site in the corresponding region. This feature appears to account for the inefficiency of the tRNA(SG)(Ala) promoter since provision of either of the wild-type TATA sequences derived from the tRNA(C)(Ala) promoter confers robust transcriptional activity. Transcriptional impairment of the wild-type tRNA(SG)(Ala) gene is not due to reduced incorporation of TBP into transcription complexes since both the tRNA(C)(Ala) and tRNA(SG)(Ala) promoters form transcription complexes that contain the same amount of TBP. Thus, the deleterious consequences of the lack of appropriate TBP-TATA contacts in the tRNA(SG)(Ala) promoter must come from failure to incorporate some other essential transcription factor(s) or to stabilize the complete complex in an active conformation.
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Affiliation(s)
- C Ouyang
- Department of Physics, University of Oregon, Eugene, Oregon 97403, USA
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Trivedi A, Young LS, Ouyang C, Johnson DL, Sprague KU. A TATA element is required for tRNA promoter activity and confers TATA-binding protein responsiveness in Drosophila Schneider-2 cells. J Biol Chem 1999; 274:11369-75. [PMID: 10196229 DOI: 10.1074/jbc.274.16.11369] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In contrast to yeast and mammalian systems, which depend principally on internal promoter elements for tRNA gene transcription, insect systems require additional upstream sequences. To understand the function of the upstream sequences, we have asked whether the Bombyx mori tRNACAla and tRNASGAla genes, which are absolutely dependent on these sequences in vitro, also require them for transcription in vivo. We introduced wild-type and mutant versions of the Bombyx tRNAAla genes into Drosophila Schneider-2 cells and found that the tRNACAla gene is efficiently transcribed and that its transcription depends strongly on the distal segment of its upstream promoter. In contrast, the tRNASGAla gene is inefficiently transcribed, and this inefficiency results from lack of a specific sequence within the distal tRNACAla upstream promoter. This sequence, 5'-TTTATAT-3', is sufficient to increase the activity of the tRNASGAla promoter to that of the tRNACAla promoter. Moreover, promoters containing the 5'-TTTATAT-3' element are stimulated by increased levels of cellular TATA-binding protein. Together these results indicate that, in insect cells, a TATA-like element is specifically required to form functional TATA-binding protein-containing complexes that promote efficient transcription of tRNA genes.
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Affiliation(s)
- A Trivedi
- Departments of Molecular Pharmacology and Biochemistry, Schools of Pharmacy and Medicine, University of Southern California, Los Angeles, California 90033, USA
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Abstract
The TATA-binding protein is a general transcription factor required by all three eukaryotic nuclear RNA polymerases. In order to study the function of this protein in the transcription of tRNA genes in the silkworm Bombyx mori, we have cloned TBP cDNA from a silkworm cDNA library. As in most other eukaryotes, TBP in silkworms is encoded by a single copy gene and contains a highly conserved C-terminal domain that includes a basic region and two direct repeats. In the less conserved N-terminal domain, silkworm TBP exhibits characteristics such as a glutamine-rich stretch and three imperfect Pro-Met-Thr-like repeats that are also found in Drosophila and human TBP. Silkworm TBP expressed in Escherichia coli and purified to apparent homogeneity binds the TATA element of the wild-type adenovirus major late promoter with nanomolar affinity.
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Affiliation(s)
- C Ouyang
- Department of Physics, University of Oregon, Eugene, OR 97403, USA
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Chang CW, Barber L, Ouyang C, Masin D, Bally MB, Madden TD. Plasma clearance, biodistribution and therapeutic properties of mitoxantrone encapsulated in conventional and sterically stabilized liposomes after intravenous administration in BDF1 mice. Br J Cancer 1997; 75:169-77. [PMID: 9010021 PMCID: PMC2063281 DOI: 10.1038/bjc.1997.28] [Citation(s) in RCA: 30] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mitoxantrone can be efficiently loaded into large unilamellar vesicles using a transmembrane pH gradient. Release studies indicate that these drug-loaded carriers are highly stable and even after dissipation of the residual pH gradient retain more than 85% of encapsulated mitoxantrone following dialysis at 37 degrees C for 5 days. In murine studies we have compared the plasma clearance and biodistribution of both mitoxantrone and liposomal lipid following intravenous administration of free drug or mitoxantrone encapsulated in either conventional or sterically stabilized liposomes. In contrast to the rapid blood clearance observed for free mitoxantrone, both liposomal systems provided extended circulation lifetimes, with over 90% of the drug present 1 h after administration and 15-30% remaining at 24 h. In agreement with previous reports, longer plasma half-lives were observed for sterically stabilized liposomes than for conventional systems. In addition, a strong correlation between drug and carrier biodistribution was seen, with uptake occurring mainly in the liver and spleen and paralleling plasma clearance. This would suggest that tissue disposition reflects that of drug-loaded liposomes rather than the individual components. Liposomal encapsulation also significantly reduced mitoxantrone toxicity, allowing administration of higher, more efficacious drug doses. In a murine L1210 tumour model, for example, no long-term survivors were seen in animal groups treated with free drug, whereas at the maximum therapeutic dose of liposomal mitoxantrone survival rates of 40% were observed.
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Affiliation(s)
- C W Chang
- University of British Columbia, Department of Pharmacology and Therapeutics, Vancouver, Canada
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Ouyang C, Choice E, Holland J, Meloche M, Madden TD. Liposomal cyclosporine. Characterization of drug incorporation and interbilayer exchange. Transplantation 1995; 60:999-1006. [PMID: 7491708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A number of previous studies have examined the application of liposomes as carriers for the immunosuppressive agent cyclosporine. These studies, however, have generated equivocal results, particularly with regard to the therapeutic properties of such systems. In the present work, we have characterized cyclosporine incorporation into well defined liposomes, large unilamellar vesicles, and have examined the stability of drug association. Contrary to some earlier reports, we show that only modest levels of cyclosporine can be accommodated in the liposomal membrane and that the extent of drug incorporation is greatly reduced as the bilayer cholesterol content is increased. Furthermore, we demonstrate that cyclosporine, despite its hydrophobic character, can rapidly exchange between vesicles. This raises the possibility that, after i.v. administration, drug migration to other blood components might negate the potential benefits arising from liposomal delivery. In a companion paper, therefore (Choice et al., Transplantation, 1995, this issue), we have followed the pharmacokinetics and biodistribution of liposomal cyclosporine in a study that examined the behavior of both the drug and the liposomal carrier.
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Affiliation(s)
- C Ouyang
- Department of Pharmacology, University of British Columbia, Vancouver, Canada
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Abstract
Interaction of fibrinogen with its receptors (glycoprotein IIb/IIIa complex) on platelet membranes leads to platelet aggregation. By means of gel filtration, CM-Sephadex C-50, and reverse-phase HPLC, an antiplatelet peptide, gabonin, was purified from the venom of Bitis gabonica. The purified protein migrates as a 21,100-Da polypeptide on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions and as a 11,000-Da peptide in the presence of beta-mercaptoethanol, indicating that gabonin is a disulfide-linked dimer. It is a polypeptide consisting of about 84 amino acid residues, rich in Asp, Pro, and half-cystine. Gabonin dose-dependently inhibited human platelet aggregation stimulated by ADP, collagen, U46619, or thrombin in preparations of platelet-rich plasma and platelet suspension (IC50 = 340-1600 nM). It also blocked platelet aggregation of whole blood. However, it apparently did not affect the initial shape change and only slightly reduced ATP release caused by aggregation agonists. Gabonin did not inhibit the rise of cytosolic calcium in Quin-2-loaded platelets stimulated by thrombin. In addition, gabonin dose-dependently inhibited fibrinogen-induced aggregation of elastase-treated platelets. In conclusion, gabonin inhibits platelet aggregation mainly through the blockade of fibrinogen binding toward fibrinogen receptors of the activated platelets.
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Affiliation(s)
- T F Huang
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei
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Abstract
Snake venoms can affect blood coagulation and platelet function in various ways. The physicochemical properties and the mechanisms of actions of the snake venom components affecting blood coagulation and platelet function are discussed.
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Affiliation(s)
- C Ouyang
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, R.O.C
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Huang TF, Wang WJ, Teng CM, Liu CS, Ouyang C. Purification and characterization of an antiplatelet peptide, arietin, from Bitis arietans venom. Biochim Biophys Acta 1991; 1074:136-43. [PMID: 2043663 DOI: 10.1016/0304-4165(91)90052-i] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
By means of Fractogel TSK-50, CM-Sephadex C-50 column chromatography, gel filtrations on Sephadex G-75 and Sephacryl S-200 columns and reverse-phase HPLC, an antiplatelet peptide, arietin, was purified from venom of Bitis arietans. Arietin was shown to be an Arg-Gly-Asp-containing peptide with a NH2-terminus, Ser-Pro-Pro-Val-Cys-Gly-Asn-Lys- (Mr 8500). Arietin dose-dependently inhibited aggregation of human platelet suspension stimulated by ADP, thrombin, collagen and U46619 with IC50, 1.3-2.7.10(-7) M, while it had no effect on the initial shape changes and only slightly affected ATP release of platelets caused by thrombin and collagen. Arietin also blocked platelet aggregation in platelet-rich plasma and whole blood, and inhibited thrombin-induced clot retraction of platelet-rich plasma. Furthermore, arietin (6.5.10(-8) M) completely blocked the fibrinogen-induced aggregation of elastase-treated platelets, indicating that arietin interferes with the fibrinogen binding to fibrinogen receptors on platelet membranes. In conclusion, arietin, an Arg-Gly-Asp-containing peptide, inhibits platelet aggregation probably through the blockade of fibrinogen binding to the activated platelets.
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Affiliation(s)
- T F Huang
- Pharmacological Institute, college of Medicine, National Taiwan University, Taipei
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Abstract
Arietin, an Arg-Gly-Asp containing peptide from venom of Bitis arietans, inhibited aggregation of platelets stimulated by a variety of agonists with a similar IC50, 1.3-2.7.10(-7) M. It blocked aggregation through the interference of fibrinogen binding to fibrinogen receptors on platelet surface. In this paper, we further demonstrated that arietin had no significant effect on the intracellular mobilization of Ca2+ in Quin2-AM-loaded platelets stimulated by thrombin. It inhibited 125I-fibrinogen binding to ADP-stimulated platelets in a competitive manner (IC50, 1.1.10(-7) M). 125I-arietin bound to unstimulated, ADP-stimulated and elastase-treated platelets in a saturable manner and its Kd values were estimated to be 3.4.10(-7), 3.4.10(-8) and 6.5.10(-8) M, respectively, while the corresponding binding sites were 46,904, 48,958 and 34,817 per platelet, respectively. Arg-Gly-Asp-Ser (RGDS) inhibited 125I-arietin binding to ADP-stimulated platelets in a competitive manner. RGD-containing peptides, including trigramin and rhodostomin, EDTA and monoclonal antibody, 7E3, raised against glycoprotein IIb-IIIa complex, inhibited 125I-arietin binding to ADP-stimulated platelets, indicating that the binding sites of arietin appear to be located at or near glycoprotein IIb-IIIa complex. In conclusion, arietin and other RGD-containing trigramin-like peptides preferentially bind to the fibrinogen receptors associated with glycoprotein IIb-IIIa complex of the activated platelets, thus leading to the blockade of fibrinogen binding to its receptors and subsequent aggregation. The presence of RGD of arietin is essential for the expression of its biological activity. Its binding sites are overlapped with those of trigramin, rhodostomin and the monoclonal antibody, 7E3.
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Affiliation(s)
- T F Huang
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei
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Huang TF, Wang WJ, Ouyang C. Arietin, a snake venom peptide, inhibits platelet aggregation by acting as fibrinogen receptor antagonist of the activated human platelets. Eur J Pharmacol 1990. [DOI: 10.1016/0014-2999(90)94036-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Huang TF, Wang WJ, Ouyang C. Arietin, a snake venom peptide, inhibits platelet aggregation by acting as fibrinogen receptor antagonist of the activated human platelets. Eur J Pharmacol 1990. [DOI: 10.1016/0014-2999(90)93569-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ouyang C, Teng CM, Huang TF. Characterization of snake venom principles affecting blood coagulation and platelet aggregation. Adv Exp Med Biol 1990; 281:151-63. [PMID: 2102609 DOI: 10.1007/978-1-4615-3806-6_15] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C Ouyang
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, ROC
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Teng CM, Hung ML, Huang TF, Ouyang C. Triwaglerin: a potent platelet aggregation inducer purified from Trimeresurus wagleri snake venom. Biochim Biophys Acta 1989; 992:258-64. [PMID: 2775787 DOI: 10.1016/0304-4165(89)90083-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Trimeresurus wagleri venom is the most potent inducer of platelet aggregation among the seven Trimeresurus snake venoms tested. By means of CM-Sephadex C-50 column chromatography, T. wagleri venom was separated into 19 fractions. Fraction XVI possessed the strongest aggregating activity and was further purified by Sephadex G-75 and on heparin-agarose columns, and finally Triwaglerin, with a molecular weight of 68000, was obtained. Its aggregating and ATP-releasing activity was dose-dependent and 10-times more potent than the crude venom. Triwaglerin was devoid of any of the enzymatic activities possessed by the crude venom. Triwaglerin-induced aggregation was not affected by indomethacin, creatine phosphate/creatine phosphokinase (CP/CPK), platelet-activating factor (PAF) antagonists, verapamil or heparin, but was inhibited completely by mepacrine, imipramine and forskolin and markedly by tetracaine and sodium nitroprusside. Thromboxane B2 formation caused by Triwaglerin was suppressed by mepacrine, imipramine and indomethacin. R59022 and TMB-8 caused a synergistic inhibitory effect against Triwaglerin-induced aggregation. These data suggest that Triwaglerin activates platelets in a unique action which is independent of formation of thromboxane A2 and PAF, or release of ADP.
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Affiliation(s)
- C M Teng
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, China
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Abstract
Seven edema-producing fractions were isolated from Trimeresurus mucrosquamatus snake venom by CM-Sephadex C-50 chromatography and further purified by gel filtration on a Sephadex G-75 column. They were homogeneous as judged by electrophoresis on polyacrylamide gels. The mol. wts were estimated to be 26,900 (Fr. IV-2), 21,500 (Fr. X-2), 23,000 (Fr. XII-2), 21,800 (Fr. XIII-2), 24,600 (Fr. XIV-2), 80,000 (Fr. XVIII-1) and 22,500 (Fr. XXII-2). Fraction IV-2 had weak esterase activity, fractions X-2, XII-2, XIII-2 and XIV-2 possessed proteolytic activity toward casein and fibrinogen, while fractions XVIII-1 and XXII-2 possessed phospholipase A2 activity. Fractions with phospholipase A2 activity had greater edema-producing activity than those with protease and/or esterase activity. It is concluded that the edema caused by T. mucrosquamatus venom may be due to phospholipases A2, proteases and esterases.
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Affiliation(s)
- C M Teng
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei
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Hale PM, Cease KB, Houghten RA, Ouyang C, Putney S, Javaherian K, Margalit H, Cornette JL, Spouge JL, DeLisi C. T cell multideterminant regions in the human immunodeficiency virus envelope: toward overcoming the problem of major histocompatibility complex restriction. Int Immunol 1989; 1:409-15. [PMID: 2484961 DOI: 10.1093/intimm/1.4.409] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [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: 01/01/2023] Open
Abstract
Helper T cell determinants should be an important component of an anti-human immunodeficiency virus (HIV) vaccine aimed at either antibody or cytotoxic T cell immunity. However, model protein studies have raised concern about the usefulness of any single determinant, because a given determinant is likely to be seen by only a small subset of major histocompatibility complex (MHC) types within the population. Here, we use 44 peptides, including ones predicted and not predicted on the basis of amphipathicity to be potential T cell sites, to locate T cell antigenic determinants recognized by mice of four MHC haplotypes immunized with the whole gp 160 envelope protein. Although the preselection of peptides necessitates caution in a statistical analysis, alpha-amphipathic peptides predominated among sites eliciting the strongest response. Although we have not tested the entire sequence, we have identified six multideterminant regions, in which overlapping peptides are recognized by mice of either three or all four MHC types. Four of the six regions have sequences relatively conserved among HIV-1 isolates. The existence of such multideterminant regions recognized by multiple MHC haplotypes suggests the possibility that use of peptides longer than a minimal determinant and containing several overlapping determinants may be a possible approach to circumvent the serious problem of MHC restriction in peptide vaccines aimed at eliciting T cell immunity.
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Affiliation(s)
- P M Hale
- Metabolism Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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Huang TF, Wu YJ, Ouyang C. Characterization of a potent platelet aggregation inhibitor from Agkistrodon rhodostoma snake venom. Biochim Biophys Acta 1987; 925:248-57. [PMID: 3620499 DOI: 10.1016/0304-4165(87)90189-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
By means of CM-Sephadex C-50 column chromatography and gel filtration on Sephadex G-75 and G-50 columns, a potent platelet aggregation inhibitor was purified and characterized. It was a glycoprotein with a molecular weight of 31,000. It was devoid of phospholipase A, ADPase, esterase and fibrino(geno)lytic activities. It inhibited dose-dependently the aggregation of washed platelets induced by collagen, thrombin, sodium arachidonate, platelet activating factor and ionophore A23187 with a similar IC50 (5-10 micrograms/ml). It was also active in platelet-rich plasma, with an IC50 of 10-15 micrograms/ml. The venom inhibitor reduced the elasticity of whole blood clot and inhibited the thrombin-induced clot retraction of platelet-rich plasma. These activities were related to its inhibitory activity on platelet aggregation rather than blood coagulation. The venom inhibitor had various effects on [14C]serotonin release stimulated by aggregation agonists. It had no effect on thromboxane B2 formation of platelets stimulated by sodium arachidonate, collagen and ionophore A23187. The presence of this venom inhibitor prior to the initiation of aggregation was a prerequisite for the maintenance of its maximal activity. It showed a similar inhibitory effect on collagen or thrombin-induced aggregation even when it was added after the platelets had undergone the shape change. High fibrinogen levels partially antagonized its activity. The venom inhibitor completely inhibited the fibrinogen-induced aggregation of alpha-chymotrypsin-treated platelets. It is concluded that this venom inhibitor interferes with the interaction of fibrinogen with fibrinogen receptors, leading to inhibition of aggregation.
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Cease KB, Margalit H, Cornette JL, Putney SD, Robey WG, Ouyang C, Streicher HZ, Fischinger PJ, Gallo RC, DeLisi C. Helper T-cell antigenic site identification in the acquired immunodeficiency syndrome virus gp120 envelope protein and induction of immunity in mice to the native protein using a 16-residue synthetic peptide. Proc Natl Acad Sci U S A 1987; 84:4249-53. [PMID: 2438696 PMCID: PMC305062 DOI: 10.1073/pnas.84.12.4249] [Citation(s) in RCA: 139] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Much effort has been devoted to the analysis of antibodies to acquired immunodeficiency syndrome virus antigens, but no studies, to our knowledge, have defined antigenic sites of this virus that elicit T-cell immunity, even though such immunity is important in protection against many other viruses. T cells tend to recognize only a limited number of discrete sites on a protein antigen. Analysis of immunodominant helper T-cell sites has suggested that such sites tend to form amphipathic helices. An algorithm based on this model was used to identify two candidate T-cell sites, env T1 and env T2, in the envelope protein of human T-lymphotropic virus type IIIB that were conserved in other human immunodeficiency virus isolates. Corresponding peptides were synthesized and studied in genetically defined inbred and F1 mice for induction of lymph node proliferation. After immunization with a 426-residue recombinant envelope protein fragment, significant responses to native gp 120, as well as to each peptide, were observed in both F1 combinations studied. Conversely, immunization with env T1 peptide induced T-cell immunity to the native gp 120 envelope protein. The genetics of the response to env T1 peptide were further examined and revealed a significant response in three of four independent major histocompatibility haplotypes tested, an indication of high frequency responsiveness in the population. Identification of helper T-cell sites should facilitate development of a highly immunogenic, carrier-free vaccine that induces T-cell and B-cell immunity. The ability to elicit T-cell immunity to the native viral protein by immunization with a 16-residue peptide suggests that such sites represent potentially important components of an effective vaccine for acquired immunodeficiency syndrome.
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Teng CM, Kuo YP, Lee LG, Ouyang C. Effect of cobra venom phospholipase A2 on platelet aggregation in comparison with those produced by arachidonic acid and lysophophatidylcholine. Thromb Res 1986; 44:875-86. [PMID: 3099424 DOI: 10.1016/0049-3848(86)90033-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Cobra venom phospholipase A2 induced a biphasic effect on washed rabbit platelets. The first phase was a reversible aggregation which was dependent on stirring and extracellular calcium. The aggregation and thromboxane B2 formation were inhibited by indomethacin, mepacrine, tetracaine and imipramine, while PGE1 and sodium nitroprusside inhibited only the aggregation, but not the thromboxane B2 formation. The second phase was an inhibitory effect on platelet aggregation induced by arachidonic acid, PAF, ADP or collagen but not that by thrombin or ionophore A23187. The longer the incubation time of cobra venom phospholipase A2 with platelets, the more the inhibitory effect. The aggregating and anti-aggregating effects could be overcome by bovine serum albumin. Lysophosphatidylcholine (Lyso-PC) and arachidonic acid showed synergistic inhibition in platelet aggregation. Lyso-PC decreased thromboxane B2 formation in platelets formed by collagen. The inhibitory effect of Lyso-PC on platelet aggregation was more marked at lower calcium concentrations. It is concluded that the aggregating effect of exogenous addition of venom phospholipase A2 is due to thromboxane formation and the antiplatelet effect is similar to those produced by arachidonic acid and lysophosphatidylcholine.
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Abstract
Among all the purified components from A. acutus venom, including ADPase, 5'-nucleotidase, phospholipase A2 and fibrinogenases, only the venom ADPase (50-100 micrograms/ml) shows marked inhibitory action on ADP (10 microM)-, collagen (10 micrograms/ml)- and sodium arachidonate (100 microM)-induced platelet aggregations of rabbit platelet-rich plasma. The venom 5'-nucleotidase (100 micrograms/ml) inhibited ADP-induced platelet aggregation by 31 +/- 4% (n = 4, P less than 0.05). Fibrinogenolytic enzymes (fractions I and IX, 100 micrograms/ml) did not significantly inhibit platelet aggregation induced by ADP (10 microM), collagen (10 micrograms/ml) or sodium arachidonate (100 microM). However, when the fibrinogenase (fraction IX, 100 micrograms/ml) was preincubated with platelet-rich plasma for 30 min it inhibited collagen (20 micrograms/ml)- and ADP (10 microM)-induced platelet aggregations by 34 +/- 9% (n = 4, P less than 0.05) and 35 +/- 6% (n = 4, P less than 0.05), respectively. The phospholipase A2 (100 micrograms/ml) did not affect platelet aggregation. The venom ADPase is a single chain polypeptide with a molecular weight of 94,000. The specific ADPase activity is estimated to be 4.3 mu moles Pi/min/mg of protein. It also possesses phosphodiesterase and weak 5'-nucleotidase activities.
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Ouyang C, Hwang LJ, Huang TF. Inhibition of rabbit platelet aggregation by alpha-fibrinogenase purified from Calloselasma rhodostoma (Malayan pit viper) venom. Taiwan Yi Xue Hui Za Zhi 1985; 84:1197-206. [PMID: 3868694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Teng CM, Ouyang C, Lin SC. Species difference in the fibrinogenolytic effects of alpha- and beta-fibrinogenases from Trimeresurus mucrosquamatus snake venom. Toxicon 1985; 23:777-82. [PMID: 4089873 DOI: 10.1016/0041-0101(85)90008-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Alpha- and beta-fibrinogenases prepared from Trimeresurus mucrosquamatus venom digested specifically the alpha(A) and beta(B) chains of the fibrinogen molecule, respectively. alpha-Fibrinogenase digested bovine fibrinogen more markedly than human fibrinogen, while beta-fibrinogenase digested human fibrinogen more markedly than bovine fibrinogen. Human fibrin was also digested by both enzymes. Plasma fibrinogens of 4 animal species were digested by alpha-fibrinogenase to the same degree, while those by beta-fibrinogenase in the following order: human greater than dog greater than guinea-pig greater than rabbit. The fibrinogenolytic effects of alpha-fibrinogenase on human fibrinogen were strongly inhibited by sera of the 4 animal species, while those of beta-fibrinogenase were inhibited in the following order: rabbit greater than guinea-pig greater than dog greater than human. It was concluded that the different activities of the protease inhibitors in the plasma of animal species are mainly responsible for the sensitivity differences.
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Teng CM, Chen YH, Ouyang C. Biphasic effect on platelet aggregation by phospholipase a purified from Vipera russellii snake venom. Biochim Biophys Acta 1984; 772:393-402. [PMID: 6426517 DOI: 10.1016/0005-2736(84)90156-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A basic phospholipase A was isolated from Vipera russellii snake venom. It induced a biphasic effect on washed rabbit platelets suspended in Tyrode's solution. The first phase was a reversible aggregation which was dependent on stirring and extracellular calcium. The second phase was an inhibitory effect on platelet aggregation, occurring 5 min after the addition of the venom phospholipase A without stirring or after a recovery from the reversible aggregation. The aggregating phase could be inhibited by indomethacin, tetracaine, papaverine, creatine phosphate/creatine phosphokinase, mepacrine, verapamil, sodium nitroprusside, prostaglandin E1 or bovine serum albumin. The venom phospholipase A released free fatty acids from synthetic phosphatidylcholine and intact platelets. p-Bromophenacyl bromide-modified venom phospholipase A lost its phospholipase A enzymatic and platelet-aggregating activities, but protected platelets from the aggregation induced by the native enzyme. The second phase of the venom phospholipase A action showed a different degree of inhibition on platelet aggregation induced by some activators in following order: arachidonic acid greater than collagen greater than thrombin greater than ionophore A23187. The longer the incubation time or the higher the concentration of the venom phospholipase A, the more pronounced was the inhibitory effect. The venom phospholipase A did not affect the thrombin-induced release reaction which was caused by intracellular Ca2+ mobilization in the presence of EDTA, but inhibited collagen-induced release reaction which was caused by Ca2+ influx from extracellular medium. The inhibitory effect of the venom phospholipase A and also lysophosphatidylcholine or arachidonic acid could be antagonized or reversed by bovine serum albumin. It was concluded that the first stimulatory phase of the venom phospholipase A action might be due to arachidonate liberation from platelet membrane. The second phase of inhibition of platelet aggregation and the release of ATP might be due to the inhibitory action of the split products produced by this venom phospholipase A.
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Teng CM, Chen YH, Ouyang C. Purification and properties of the main coagulant and anticoagulant principles of Vipera russellii snake venom. Biochim Biophys Acta 1984; 786:204-12. [PMID: 6722170 DOI: 10.1016/0167-4838(84)90090-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Vipera russellii venom was separated into thirteen fractions by means of DEAE-Sephadex A-50 column chromatography. Fraction III possessed anticoagulant and phospholipase A activities and Fraction XI possessed procoagulant and caseinolytic activities, both were further purified by gel filtration on Sephacryl S-200 column. Purified procoagulant (Component II) was a two-chain protein with molecular weight of 86 000 consisting of A-chain (Mr 66 000) and B-chain (Mr 20 000). It was a glycoprotein containing 7.8% neutral sugar and 715 amino-acid residues. The procoagulant activity was 10-times that of the crude venom. It was an acidic proteinase with isoelectric point of pH 4.2. Upon heat treatment at 60 degrees C, Component II was stable at pH 5.5 and 7.2 for 3 h, but was destroyed completely after 30 min at pH 8.9. It was devoid of esterase or amidase activity. Purified anticoagulant (Component I) was a single peptide chain with molecular weight of 16 000. It was carbohydrate free and contained 136 amino-acid residues. It was a basic protein with an isoelectric point of larger than pH 10. It was a potent phospholipase A with an enzymatic activity of 510 +/- 30 mumol/min per mg using phosphatidylcholine as substrate, and 1 microgram/ml was sufficient to cause 100% hemolysis by the indirect hemolytic method. Upon heat treatment at 90 degrees C, Component I was heat stable at pH 5.5 for more than 3 h, but was destroyed completely after 2 h at pH 7.2 and 8.9. The anticoagulant activity of Component I could be neutralized by platelet factor 3, tissue thromboplastin and cephalin.
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Abstract
The platelet aggregation inhibitor (PAI) purified from T. gramineus snake venom inhibited platelet aggregation even when it was added after platelet shape change had occurred. It inhibited the initial platelet aggregation phase in rabbit platelet-rich plasma (PRP), but not the second lytic phase induced by thimerosal (0.5 mM), a -SH reagent. In human platelet-rich plasma, the venom inhibitor also inhibited the platelet aggregation induced by ADP, collagen, epinephrine or ristocetin. The epinephrine-induced platelet aggregation was more susceptible to the venom inhibitor. The venom inhibitor (10 micrograms/ml) as well as N-ethylmaleimide (1.2 mM), a -SH reagent, completely inhibited the thrombin-induced clot retraction of PRP. It is concluded that PAI acts on a common step of platelet aggregation. It acts on membrane -SH containing macromolecule which directly mediates the platelet aggregation subsequent to platelet shape change.
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Abstract
Effects of seven purified phospholipases A2 from the venoms of snakes (Naja naja atra, Trimeresurus mucrosquamatus and T. gramineus) and honey bee (Apis mellifera) on rabbit washed platelet suspension in the absence of bovine serum albumin have been studied. Only phospholipases A2 from N. n. atra, T. mucrosquamatus and A. mellifera venoms induced platelet aggregation with small amounts of 14C-serotonin release. They showed tachyphylaxis and also cross-tachyphylaxis in inducing platelet aggregation. The former two phospholipases A2 exhibited biphasic responses in which irreversible aggregations appeared at concentrations of 1-10 micrograms/ml. At higher concentrations, they elicited the reversible aggregation. Exogenous Ca2+ was essential to their activity. Indomethacin and EDTA completely abolished both phospholipase A2 induced platelet shape change and aggregation, while mepacrine, prostaglandin E1, verapamil and nitroprusside inhibited only the aggregation response. p-Bromophenacyl bromide-modified phospholipases A2, which almost completely lost enzymatic activity, failed to induce platelet aggregation. Phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol inhibited the phospholipase A2-induced platelet aggregation. These phospholipases A2 induced thromboxane B2 formation which was inhibited by EDTA and indomethacin, but not by prostaglandin E1. Pre-treatment of platelet suspension with phospholipase A2 from N. n. atra or A. mellifera venom (50 micrograms/ml) inhibited platelet aggregation induced by sodium arachidonate or collagen, but not that induced by thrombin or ionophore A-23187. Exogenous sodium arachidonate or lysophosphatidylcholine also showed unaltered inhibitory spectrum on platelet aggregation. It is concluded that phospholipases A2 induce platelet aggregation by virtue of their enzymatic activity, cleaving the membrane phospholipids resulting in arachidonic acid release and formation of thromboxane A2. On the other hand, the cleaved products, lysophosphatidylcholine, arachidonic acid or arachidonate metabolites (via lipoxygenase pathway) may be responsible for anti-platelet activity.
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Abstract
In addition to alpha-fibrinogenase (hemorrhagin I, HR1), a potent hemorrhagic principle (hemorrhagin II, HR2) was purified from Trimeresurus gramineus venom. It was homogeneous as judged by SDS-polyacrylamide gel electrophoresis. HR2 was a single peptide chain containing 10% carbohydrate with a molecular weight of 81,500. It possessed 669 amino acid residues per molecule, while HR1 contained only 203 amino acid residues per molecule with a molecular weight of 23,500. Both hemorrhagins possessed proteolytic activities toward fibrinogen, casein and azocoll. However, the proteolytic activities of HR1 were much more potent than those of HR2. They were devoid of TAME-esterase and phospholipase A2 activities which were found in crude venom. beta-Mercaptoethanol and antivenin completely inhibited the hemorrhagic activities of HR1 and HR2, while epsilon-aminocaproic acid, trasylol, p-bromophenacyl bromide, phenylmethanesulfonyl fluoride and soybean trypsin inhibitor did not. EDTA completely inhibited the hemorrhagic, fibrinogenolytic and caseinolytic activities of HR1. EDTA also completely inhibited the caseinolytic and fibrinogenolytic activities of HR2, but only partially inhibited its hemorrhagic activity. Subsequent addition of Zn2+ (5 mM) reversed the EDTA-induced inhibitory effect on the hemorrhagic activity of HR1. However, ZN2+ did not reverse the EDTA-induced inhibitory effect on the HR2-induced hemorrhagic activity. These hemorrhagins were found to be ZN2+-containing metalloproteinases. Therefore, the hemorrhagic activity of HR1 seems to be related to its proteolytic activity while that of HR2 seems to be unrelated to its proteolytic activity.
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Abstract
Cardiotoxin, isolated from Naja naja atra snake venom, potentiates platelet aggregation induced by ADP, thrombin, collagen and venom phospholipase A2. The malondialdehyde formation caused by ADP, thrombin and venom phospholipase A2 were also increased in the presence of cardiotoxin. Both potentiation of aggregation and increase in malondialdehyde were blocked by indomethacin or Ca2+ (5 mM or 0.05 mM). Cardiotoxin did not potentiate thrombin-induced aggregation of p-bromophenacyl bromide-modified platelets. Thromboxane B2 formation induced by thrombin or collagen was also increased by cardiotoxin, while that by arachidonate was not affected. As a membrane-active polypeptide, cardiotoxin might augment the Ca2+-flux during the activation of the platelet membrane by aggregation inducers and then increase the activation of endogenous phospholipase A2.
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