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Yu X, Mao C, Zong S, Khan A, Wang W, Yun H, Zhang P, Shigaki T, Fang Y, Han H, Li X. Transcriptome analysis reveals self-redox mineralization mechanism of azo dyes and novel decolorizing hydrolases in Aspergillus tabacinus LZ-M. Environ Pollut 2023; 325:121459. [PMID: 36934962 DOI: 10.1016/j.envpol.2023.121459] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/16/2023] [Accepted: 03/17/2023] [Indexed: 06/18/2023]
Abstract
Bio-degradation is the most affordable method of azo dye decontamination, while its drawbacks such as aromatic amines accumulation and low degradation efficiency must be overcome. In this study, a novel mechanism of azo dye degradation by a fungus was discovered. At a concentration of 400 mg/L, the decolorization efficiency of Acid Red 73 (AR73) by Aspergillus tabacinus LZ-M was 90.28%. Metabolite analysis and transcriptome sequencing analysis revealed a self-redox process of AR73 degradation, where the electrons generated in carbon oxidation were transferred to the reduction of -C-N = and -NN. The metabolites, 2-hydroxynaphthalene and N-phenylnitrous amide were mineralized into CO2 through catechol pathway and a glycolytic process. Furthermore, the mineralization ratio of dye was computed to be 31.8% by the carbon balance and electron balance. By using comparative transcriptome, a novel decoloring enzyme Ord95 was discovered in unknown genes through gene cloning. It hydrolyzed AR73 into 2-hydroxynaphthalene and N-phenylnitrous amide, containing a glutathione S-transferase domain with three arginines as key active sites. Here the new mechanism of azo dye degradation was discovered with identification of a novel enzyme in Aspergillus tabacinus LZ-M.
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Affiliation(s)
- Xuan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Chunlan Mao
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Simin Zong
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Aman Khan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Wenxue Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Hui Yun
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Peng Zhang
- Key Laboratory for Resources Utilization Technoloy of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou, 730020, Gansu, China
| | - Toshiro Shigaki
- Laboratory of Plant Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Yitian Fang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Huawen Han
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou, 730000, Gansu, China.
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Tang H, Zhou T, Jin W, Zong S, Mamtimin T, Salama ES, Jeon BH, Liu P, Han H, Li X. Tumor-targeting engineered probiotic Escherichia coli Nissle 1917 inhibits colorectal tumorigenesis and modulates gut microbiota homeostasis in mice. Life Sci 2023; 324:121709. [PMID: 37100380 DOI: 10.1016/j.lfs.2023.121709] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 04/28/2023]
Abstract
AIMS Preliminary studies have identified the use of probiotics as a potential treatment strategy against colorectal cancer (CRC). However, natural probiotics lack direct tumor-targeting and tumor-killing activity in the intestine. This study aimed to construct a tumor-targeting engineered probiotic to combat CRC. MAIN METHODS Standard adhesion assay was performed to analyze the adherence ability of tumor-binding protein HlpA to CT26 cells. CCK-8 assay, Hoechst 33258 staining and flow cytometry analysis were used for examining cytotoxicity of tumoricidal protein azurin toward CT26 cells. An engineered probiotic Ep-AH harboring azurin and hlpA genes was developed using Escherichia coli Nissle 1917 (EcN) chassis. Antitumor effects of Ep-AH were evaluated in the azoxymethane (AOM) and dextran sodium sulfate salt (DSS)-induced CRC mice. Moreover, analysis of gut microbiota was conducted via fecal 16S rRNA gene sequencing and shotgun metagenomic sequencing. KEY FINDINGS Azurin caused a dose-dependent increase of apoptosis in CT26 cells. Ep-AH treatment reversed weight loss (p < 0.001), fecal occult blood (p < 0.01), and shortening of colon length (p < 0.001) than model group, as well as reducing tumorigenesis by 36 % (p < 0.001). Both Ep-H and Ep-A (EcN expressing HlpA or azurin) were less effective than Ep-AH. Furthermore, Ep-AH enriched the members of beneficial bacteria (e.g., Blautia and Bifidobacterium) and reversed abnormal changes of genes associated with several metabolic pathways (e.g., lipopolysaccharide biosynthesis). SIGNIFICANCE These results demonstrated that Ep-AH had excellent therapeutic benefits on cancer remission and gut microbiota modulation. Our study provides an effective strategy for anti-CRC treatment.
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Affiliation(s)
- Haibo Tang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Tuoyu Zhou
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Weilin Jin
- Institute of Cancer Neuroscience, Medical Frontier Innovation Research Center, The First Hospital of Lanzhou University, The First Clinical Medical College of Lanzhou University, Lanzhou, China
| | - Simin Zong
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Tursunay Mamtimin
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - El-Sayed Salama
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou, China
| | - Byong-Hun Jeon
- Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul, Republic of Korea
| | - Pu Liu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China
| | - Huawen Han
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China; State Key Laboratory of Grassland Agro-ecosystems, Center for Grassland Microbiome, Lanzhou University, Lanzhou, China.
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Science, Lanzhou University, Lanzhou, China.
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Yun H, Liang B, He Z, Li M, Zong S, Wang Z, Ge B, Zhang P, Li X, Wang A. Insights into methanogenesis of mesophilic-psychrophilic varied anaerobic digestion of municipal sludge with antibiotic stress. J Environ Manage 2023; 331:117278. [PMID: 36634423 DOI: 10.1016/j.jenvman.2023.117278] [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] [Received: 10/13/2022] [Revised: 01/07/2023] [Accepted: 01/08/2023] [Indexed: 06/17/2023]
Abstract
Methane production through anaerobic digestion (AD) of municipal sludge is economic and eco-friendly, which is commonly affected by temperature and pollutants residues. However, little is known about methanogenesis in psychrophilic AD (PAD) with temperature variations that simulating seasonal variations and with antibiotic stress. Here, two groups of AD systems with oxytetracycline (OTC) were operated with temperature maintained at 35 °C and 15 °C or variation to explore the influence to methanogenesis. The acetic acid was noticeably accumulated in OTC groups initially (P < 0.001). Methane production was noticeably inhibited initially in PAD with OTC, but had been stimulated later at 35 °C. The dominant acetoclastic methanogens Methanosaeta gradually decreased to 15.48% and was replaced by methylotrophic Methanomethylovorans (73.43%) in PAD with OTC. Correspondingly, the abundances of functional genes related to methylotrophic methanogenesis were also higher in these groups. Besides, genes involving in methane oxidation had over 50 times higher abundances in PAD with OTC groups in the second phase. Further investigation is essential to understand the main dynamics of methanogenesis in PAD and to clear the related molecular mechanism for future methane production regulation in sludge systems.
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Affiliation(s)
- Hui Yun
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Lanzhou, 730020, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Bin Liang
- State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, China
| | - Zhangwei He
- Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China
| | - Minghan Li
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150001, China
| | - Simin Zong
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Zhenfei Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Lanzhou, 730020, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Bin Ge
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Lanzhou, 730020, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Peng Zhang
- Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Lanzhou, 730020, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China; Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Lanzhou, 730020, China; Gansu Key Laboratory of Biomonitoring and Bioremediation for Environment Pollution, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
| | - Aijie Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Civil & Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen, 518055, China; Key Laboratory of Environmental Biotechnology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
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Yu X, Mao C, Wang W, Kulshrestha S, Zhang P, Usman M, Zong S, Hilal MG, Fang Y, Han H, Li X. Reduction of metronidazole in municipal wastewater and protection of activated sludge system using a novel immobilized Aspergillus tabacinus LZ-M. Bioresour Technol 2023; 369:128509. [PMID: 36538960 DOI: 10.1016/j.biortech.2022.128509] [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] [Received: 11/08/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Metronidazole (MNZ) accumulation inhibits municipal wastewater treatment bio-systems, and an effective solution to augment anaerobic activated sludge (AAS) is required. This research discovered that Aspergillus tabacinus LZ-M could degrade 77.39% of MNZ at 5 mg/L. MNZ was metabolized into urea, and the enzymes involved in its degradation were aminotransferase, methyltransferase, monooxygenase, and CN cleavage hydrolase. The strain was immobilized in polyurethane foam and used in AAS for the treatment of MNZ-containing municipal wastewater. The results showed that, using immobilized LZ-M, MNZ was completely removed, and the degradation efficiency of wastewater's chemical oxygen demand (COD) was increased from 11.7% to 83.31%. The extracellular polymer and ROS levels indicated that MNZ's toxicity on AAS was reduced. Furthermore, bioaugmentation stabilized its microbial community, and decreased MNZ resistance genes. These observations confirm that the immobilized fungi are effective in protecting AAS against antibiotic contamination in the treatment process of municipal wastewater.
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Affiliation(s)
- Xuan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Chunlan Mao
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Wenxue Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Saurabh Kulshrestha
- School of Biotechnology Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Solan 173212, Himachal Pradesh, India
| | - Peng Zhang
- Key Laboratory for Resources Utilization Technology of Unconventional Water of Gansu Province, Gansu Academy of Membrane Science and Technology, Duanjiatanlu #1272, Lanzhou 730020, Gansu, China
| | - Muhammad Usman
- State Key Laboratory of Grassland Agroecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, Gansu, China
| | - Simin Zong
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Mian Gul Hilal
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Yitian Fang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Huawen Han
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China
| | - Xiangkai Li
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road #222, Lanzhou 730000, Gansu, China.
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Tian B, Feng Y, Ren L, Wang T, Zong S. The Influence of Fatty Acids on Cold Hardiness of Eogystia hippophaecolus Larvae. Cryo Letters 2018; 39:166-176. [PMID: 30059563] [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: 06/08/2023]
Abstract
UNLABELLED BACKGROUND: Larvae of the Cossidae family moth Eogystia hippophaecolus bore into and overwinter in the roots of sea buckthorn, which damages this plant in China. OBJECTIVE The primary aims of the current study were to investigate the effects of fatty acids on cold hardness in overwintering larvae. MATERIALS AND METHODS The supercooling point (SCP), low temperature mortality and fatty acid composition of different overwintering larvae were assessed. RESULTS E. hippophaecolus larvae could survive for a long time at temperatures far below the SCP. Saturated fatty acids became less abundant as overwintering proceeded, while unsaturated fatty acids did the opposite. C10:0, C16:1, C16:0, C18:0, C20:0, C20:5, C22:0 and C24:0 fatty acids showed significant seasonal variation during the overwintering period. CONCLUSION E. hippophaecolus is "freezing-tolerant" and cold hardiness is enhanced by increasing fatty acid unsaturation and degrading medium- and long-chain fatty acids and eicosapentaenoic acid.
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Affiliation(s)
- B Tian
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China
| | - Y Feng
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China
| | - L Ren
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China
| | - T Wang
- Mentougou Forestry Station, Beijing, China
| | - S Zong
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing, China.
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Affiliation(s)
- S. Zong
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
| | - W. Wei
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
- Center of Analysis and TestJiangsu University, Zhenjiang 212013, China
| | - H. Cui
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
| | - Z. Jiang
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
| | - X. Lü
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
| | - M. Zhang
- Environmental Materials and Environmental Engineering Key Laboratory of Jiangsu ProvinceYangzhou 225001, China
| | - J. Xie
- School of Chemistry and Chemical EngineeringJiangsu University, Zhenjiang 212013, China
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Wang M, Zhang Q, Huang M, Zong S, Hua W, Zhou W. Pharmacokinetics, safety and tolerability of triflusal and its main active metabolite HTB in healthy Chinese subjects. Drug Res (Stuttg) 2014; 64:263-8. [PMID: 24105106 DOI: 10.1055/s-0033-1357180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Triflusal presents comparable antiplatelet activity to aspirin while presenting a more favourable safety profile, and is used in the treatment of thrombosis. The study aimed to evaluate the pharmacokinetics and safety of triflusal and its major metabolite 2-(hydroxyl)-4-(trifluoromethyl)- benzoic acid (HTB) in healthy Chinese subjects.30 healthy subjects were recruited in this randomized, single-center, and open-label, parallel, single ascending doses (300, 600, 900 mg) and multiple doses (600 mg, once daily for 7 days) study. Plasma samples were analyzed with a validated liquid chromatography tandem mass spectrometry (LC/MS/MS) method. Safety was assessed by adverse events, ECG, laboratory testing, and vital signs.Triflusal was safe and well tolerated. After single-dose administration, triflusal was rapidly absorbed with a mean Tmax of 0.55-0.92 h and a mean t1/2 kel of 0.35-0.65 h, HTB was absorbed with a mean Tmax of 2.35-3.03 h and a mean t1/2 kel of 52.5-65.57 h. Cmax and AUC for triflusal and HTB were approximately dose proportional over the 300-900 mg dose range. In the steady state, the accumulation index (R) indicated that the exposure of triflusal increased slightly with repeated dosing, and the exposure of HTB increased obviously. 3 adverse events certainly related to the investigational drugs occurred in the multiple-dose phase.Following oral dosing under fasting condition, triflusal is promptly absorbed and rapidly depleted from the systemic circulation. HTB is quickly generated from triflusal and slowly eliminated. Triflusal accumulates slightly in the body. HTB plasma concentration builds up progressively toward steady-state.
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Affiliation(s)
- M Wang
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Q Zhang
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - M Huang
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - S Zong
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - W Hua
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - W Zhou
- Clinical Pharmacology Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, China
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Zhang J, Liu H, Zhao W, Liu J, Zong S. Identification of the Sex Pheromone of Isoceras sibirica Alpheraky (Lepidoptera, Cossidae). Z NATURFORSCH C 2011. [DOI: 10.5560/znc.2011.66c0527] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [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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10
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Wang Y, Guan X, Fok KL, Li S, Zhang X, Miao S, Zong S, Koide SS, Chan HC, Wang L. A novel member of the Rhomboid family, RHBDD1, regulates BIK-mediated apoptosis. Cell Mol Life Sci 2009; 65:3822-9. [PMID: 18953687 DOI: 10.1007/s00018-008-8452-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Rhomboid family members are widely conserved and found in all three kingdoms of life. They are serine proteases and serve important regulatory functions. In the present study, a novel gene highly expressed in the testis, RHBDD1, is shown to be a new member of the Rhomboid family, participating in the cleavage of BIK, a proapoptotic member of the Bcl-2 family. The RHBDD1-involved proteolytic modification is upstream of the BIK protein degradation pathway. Mutagenesis studies show that the amino acid residues glycine142 and serine144 of RHBDD1 are crucial for its activity in cleaving BIK at a site located in the transmembrane region. Overexpression or knock-down of RHBDD1 in HEK 293T cells can reduce or enhance BIK-mediated apoptosis, respectively. The present findings suggest that, by acting as a serine protease, RHBDD1 modulates BIK-mediated apoptotic activity.
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Affiliation(s)
- Y Wang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Tsinghua University 5 Dong Dan San Tiao, Beijing, 100005, China
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Tanabe T, Kondo D, Yabe R, Takasaki I, Kurihara T, Saegusa H, Zong S. 398 IS UP-REGULATION OF NEUROSTEROID SYNTHESIS IMPORTANT FOR THE MAINTENANCE OF NEUROPATHIC PAIN? Eur J Pain 2007. [DOI: 10.1016/j.ejpain.2007.03.413] [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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Ning M, Guo Y, Pan H, Zong S, Gu Z. Preparation and characterization of EP-liposomes and Span 40-niosomes. Pharmazie 2006; 61:208-12. [PMID: 16599261] [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: 05/08/2023]
Abstract
Clotrimazole, an imidazole derivative antifungal agent, has been widely used for the treatment of mycotic infections of the genitourinary tract. In order to develop alternative formulations for the vaginal administration of clotrimazole which would provide sustained and controlled release of the appropriate drug for local vaginal therapy, liposomes/niosomes were evaluated as delivery vehicles. To optimize the preparation of the liposomes/niosomes with regard to size and entrapment efficiency, multilamellar liposomes/ niosomes containing the drug were prepared by a lipid hydration method. The liposomes/niosomes thus prepared were evaluated for their stability as drug-loaded liposomes/niosomes in simulated vaginal fluid at 37 +/- 1 degrees C. The two vesicle systems were also evaluated with regard to rat and rabbit vaginal irritation.
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Affiliation(s)
- M Ning
- Chinese Academy of Medical Science & Peking Union Medical College, Beijing, P.R. China
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Abstract
To investigate the functional role of Ca(v)2.3 channel in glucose homeostasis, we performed in vivo glucose tolerance and insulin tolerance tests together with stress-induced glucose release tests using mice deficient in Ca(v)2.3 channel (Ca(v)2.3-/-). The Ca(v)2.3-/- mice were significantly heavier than wild-type mice. In glucose tolerance and insulin tolerance tests, Ca(v)2.3-/- mice showed a significantly higher blood glucose level compared to wild-type mice. However, stress-induced blood glucose changes in Ca(v)2.3-/- mice were similar to those in wild-type mice. These results suggest that Ca(v)2.3 channel plays a role in glucose homeostasis by reducing insulin sensitivity and that Ca(v)2.3-/- mice exhibit symptoms resembling non-insulin-dependent diabetes mellitus.
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Affiliation(s)
- Y Matsuda
- Department of Pharmacology and Neurobiology, Tokyo Medical and Dental University, Tokyo, Japan
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Sakata Y, Saegusa H, Zong S, Osanai M, Murakoshi T, Shimizu Y, Noda T, Aso T, Tanabe T. Analysis of Ca(2+) currents in spermatocytes from mice lacking Ca(v)2.3 (alpha(1E)) Ca(2+) channel. Biochem Biophys Res Commun 2001; 288:1032-6. [PMID: 11689014 DOI: 10.1006/bbrc.2001.5871] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In mammalian male germ-line cells, low-voltage-activated (LVA) Ca(2+) current has been identified and its electrophysiological properties have been studied. To investigate whether alpha(1)2.3 (alpha(1E)) subunit of the voltage-dependent Ca(2+) channel codes for the LVA current, whole-cell patch clamp and following reverse transcription-polymerase chain reaction (RT-PCR) experiments were performed in pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice. Whole-cell current in acutely dissociated pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice displayed a typical profile of LVA Ca(2+) currents and kinetics with no significant differences. Single-cell RT-PCR revealed the expression of Cacna1g in the pachytene spermatocytes from Ca(v)2.3+/+ and Ca(v)2.3-/- mice in which LVA Ca(2+) currents were actually recorded. These results suggest that the Ca(v)2.3 channel makes no detectable contribution to the LVA Ca(2+) current in the pachytene spermatocyte. Instead, Ca(v)3 family such as Ca(v)3.1 may be the likely candidates responsible for the LVA currents in pachytene spermatocytes.
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Affiliation(s)
- Y Sakata
- Department of Pharmacology, Graduate School of Medicine, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan
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Hemminger BM, Zong S, Muller KE, Coffey CS, DeLuca MC, Johnston RE, Pisano ED. Improving the detection of simulated masses in mammograms through two different image-processing techniques. Acad Radiol 2001; 8:845-55. [PMID: 11724039 DOI: 10.1016/s1076-6332(03)80762-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
RATIONALE AND OBJECTIVES The purpose of this study was to determine whether contrast-limited adaptive histogram equalization (CLAHE) or histogram-based intensity windowing (HIW) improves the detection of simulated masses in dense mammograms. MATERIALS AND METHODS Simulated masses were embedded in portions of mammograms of patients with dense breasts; the mammograms were digitized at 50 microm per pixel, 12 bits deep. In two different experiments, images were printed both with no processing applied and with related parameter settings of two image-processing methods. A simulated mass was embedded in a realistic background of dense breast tissue, with its position varied. The key variables in each trial included the position of the mass, the contrast levels of the mass relative to the background, and the selected parameter settings for the image-processing method. RESULTS The success in detecting simulated masses on mammograms with dense backgrounds depended on the parameter settings of the algorithms used. The best HIW setting performed better than the best fixed-intensity window setting and better than no processing. Performance with the best CLAHE settings was no different from that with no processing. In the HIW experiment, there were no significant differences in observer performance between processing conditions for radiologists and nonradiologists. CONCLUSION HIW should be tested in clinical images to determine whether the detection of masses by radiologists can be improved. CLAHE processing will probably not improve the detection of masses on clinical mammograms.
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Affiliation(s)
- B M Hemminger
- Department of Radiology, University of North Carolina, Chapel Hill 27599-7510, USA
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16
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Lin W, Zhou X, Zhang M, Li Y, Miao S, Wang L, Zong S, Koide SS. Expression and function of the HSD-3.8 gene encoding a testis-specific protein. Mol Hum Reprod 2001; 7:811-8. [PMID: 11517287 DOI: 10.1093/molehr/7.9.811] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The nucleotide sequence of the full length HSD-3.8 cDNA (accession number AF311312), encoding a human sperm component, was determined to consist of 3818 bp with a reading frame of 2778 bp encoding a deduced polypeptide composed of 926 amino acids. A 0.7 kb fragment containing three immunological epitopes of HSD-3.8 cDNA was prepared and used to construct recombinant expression vectors. The constructs were transformed into E.coli BL-21, and the fusion proteins were expressed, isolated and purified. Using the polyclonal antibodies raised against the purified expressed fusion proteins, positive immunostaining occurred over the surface of the postacrosomal zone of human spermatozoa and of germ cells within the seminiferous epithelium of human testis. Intense staining of large pachytene primary spermatocytes occurred. The capacity of the recombinant protein to reduce fertility as an immunogen in adult female rats was assessed. Immunized animals were infertile or exhibited marked reduction in their fertility. Analysis of the deduced HSD-3.8 polypeptide revealed the presence of a tetratricopeptide repeat (TPR) motif, a P-loop sequence that acts as a binding site for ATP/GTP and phosphorylation sites for PKC, CK2 and cAMP/cGMP-dependent protein kinases. A blot overlay assay with [alpha-(32)P]GTP showed that the polypeptide encoded by the 0.7 kb fragment of HSD-3.8 is a GTP binding protein. It was also shown to possess GTPase activity and to be phosphorylated by PKC in vitro. In conclusion, HSD-3.8 is a GTP binding protein and its activity may be regulated by phosphorylation.
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Affiliation(s)
- W Lin
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, 5 Dong Dan 3-Tiao, Beijing 100005, People's Republic of China
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17
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Kubota M, Murakoshi T, Saegusa H, Kazuno A, Zong S, Hu Q, Noda T, Tanabe T. Intact LTP and fear memory but impaired spatial memory in mice lacking Ca(v)2.3 (alpha(IE)) channel. Biochem Biophys Res Commun 2001; 282:242-8. [PMID: 11263998 DOI: 10.1006/bbrc.2001.4572] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the functional roles of the Ca(v)2.3 (alpha(1E)) channel in hippocampal CA1 pyramidal neurons, we studied in vitro synaptic properties and in vivo behaviors of the Ca(v)2.3 gene deficient mice. The Ca(v)2.3 channel mRNA was identified in the hippocampal formation of the wild-type mouse by in situ hybridization. The basic excitatory synaptic transmission and long-term potentiation by theta-burst stimulation were intact in CA1 region of Ca(v)2.3-/- mice. We performed two forms of behavioral tests to examine the hippocampus-dependent function, i.e., emotional and spatial learning tests. The Ca(v)2.3-/- mice were able to establish and maintain fear memories. Although general improvement in the performance of Morris water maze test was seen in Ca(v)2.3-/- mice, they displayed an obvious impairment in the probe test. These results suggest that the Ca(v)2.3 channel plays some role in formation of the accurate spatial memory but not of the fear memory.
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Affiliation(s)
- M Kubota
- Department of Pharmacology and Neurobiology, Tokyo Medical and Dental University, Tokyo, Japan
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18
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Tateyama M, Zong S, Tanabe T, Ochi R. Properties of voltage-gated Ca(2+) channels in rabbit ventricular myocytes expressing Ca(2+) channel alpha(1E) cDNA. Am J Physiol Cell Physiol 2001; 280:C175-82. [PMID: 11121389 DOI: 10.1152/ajpcell.2001.280.1.c175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Using the whole-cell patch-clamp technique, we have studied the properties of alpha(1E) Ca(2+) channel transfected in cardiac myocytes. We have also investigated the effect of foreign gene expression on the intrinsic L-type current (I(Ca,L)). Expression of green fluorescent protein significantly decreased the I(Ca,L). By contrast, expression of alpha(1E) with beta(2b) and alpha(2)/delta significantly increased the total Ca(2+) current, and in these cells a Ca(2+) antagonist, PN-200-110 (PN), only partially blocked the current. The remaining PN-resistant current was abolished by the application of a low concentration of Ni(2+) and was little affected by changing the charge carrier from Ca(2+) to Ba(2+) or by beta-adrenergic stimulation. On the basis of its voltage range for activation, this channel was classified as a high-voltage activated channel. Thus the expression of alpha(1E) did not generate T-like current in cardiac myocytes. On the other hand, expression of alpha(1E) decreased I(Ca,L) and slowed the I(Ca,L) inactivation. This inactivation slowing was attenuated by the beta(2b) coexpression, suggesting that the alpha(1E) may slow the inactivation of I(Ca,L) by scrambling with alpha(1C) for intrinsic auxiliary beta.
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MESH Headings
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, L-Type/ultrastructure
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cells, Cultured/ultrastructure
- DNA, Complementary/metabolism
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Genes, Reporter/physiology
- Green Fluorescent Proteins
- Heart Ventricles/drug effects
- Heart Ventricles/metabolism
- Heart Ventricles/ultrastructure
- Indicators and Reagents/metabolism
- Isoproterenol/pharmacology
- Isradipine/pharmacology
- Luminescent Proteins/genetics
- Myocardium/metabolism
- Myocardium/ultrastructure
- Nickel/pharmacology
- Rabbits
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-1/metabolism
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Affiliation(s)
- M Tateyama
- Department of Physiology, Juntendo University School of Medicine, Tokyo 113-8421, Japan
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19
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Pisano ED, Cole EB, Major S, Zong S, Hemminger BM, Muller KE, Johnston RE, Walsh R, Conant E, Fajardo LL, Feig SA, Nishikawa RM, Yaffe MJ, Williams MB, Aylward SR. Radiologists' preferences for digital mammographic display. The International Digital Mammography Development Group. Radiology 2000; 216:820-30. [PMID: 10966717 DOI: 10.1148/radiology.216.3.r00se48820] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [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: 11/11/2022]
Abstract
PURPOSE To determine the preferences of radiologists among eight different image processing algorithms applied to digital mammograms obtained for screening and diagnostic imaging tasks. MATERIALS AND METHODS Twenty-eight images representing histologically proved masses or calcifications were obtained by using three clinically available digital mammographic units. Images were processed and printed on film by using manual intensity windowing, histogram-based intensity windowing, mixture model intensity windowing, peripheral equalization, multiscale image contrast amplification (MUSICA), contrast-limited adaptive histogram equalization, Trex processing, and unsharp masking. Twelve radiologists compared the processed digital images with screen-film mammograms obtained in the same patient for breast cancer screening and breast lesion diagnosis. RESULTS For the screening task, screen-film mammograms were preferred to all digital presentations, but the acceptability of images processed with Trex and MUSICA algorithms were not significantly different. All printed digital images were preferred to screen-film radiographs in the diagnosis of masses; mammograms processed with unsharp masking were significantly preferred. For the diagnosis of calcifications, no processed digital mammogram was preferred to screen-film mammograms. CONCLUSION When digital mammograms were preferred to screen-film mammograms, radiologists selected different digital processing algorithms for each of three mammographic reading tasks and for different lesion types. Soft-copy display will eventually allow radiologists to select among these options more easily.
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Affiliation(s)
- E D Pisano
- Dept of Radiology, University of North Carolina CB7510, Chapel Hill, NC 27599-7510, USA.
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20
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Saegusa H, Kurihara T, Zong S, Minowa O, Kazuno A, Han W, Matsuda Y, Yamanaka H, Osanai M, Noda T, Tanabe T. Altered pain responses in mice lacking alpha 1E subunit of the voltage-dependent Ca2+ channel. Proc Natl Acad Sci U S A 2000; 97:6132-7. [PMID: 10801976 PMCID: PMC18570 DOI: 10.1073/pnas.100124197] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
alpha(1) subunit of the voltage-dependent Ca(2+) channel is essential for channel function and determines the functional specificity of various channel types. alpha(1E) subunit was originally identified as a neuron-specific one, but the physiological function of the Ca(2+) channel containing this subunit (alpha(1E) Ca(2+) channel) was not clear compared with other types of Ca(2+) channels because of the limited availability of specific blockers. To clarify the physiological roles of the alpha(1E) Ca(2+) channel, we have generated alpha(1E) mutant (alpha(1E)-/-) mice by gene targeting. The lacZ gene was inserted in-frame and used as a marker for alpha(1E) subunit expression. alpha(1E)-/- mice showed reduced spontaneous locomotor activities and signs of timidness, but other general behaviors were apparently normal. As involvement of alpha(1E) in pain transmission was suggested by localization analyses with 5-bromo-4-chloro-3-indolyl beta-d-galactopyranoside staining, we conducted several pain-related behavioral tests using the mutant mice. Although alpha(1E)+/- and alpha(1E)-/- mice exhibited normal pain behaviors against acute mechanical, thermal, and chemical stimuli, they both showed reduced responses to somatic inflammatory pain. alpha(1E)+/- mice showed reduced response to visceral inflammatory pain, whereas alpha(1E)-/- mice showed apparently normal response compared with that of wild-type mice. Furthermore, alpha(1E)-/- mice that had been presensitized with a visceral noxious conditioning stimulus showed increased responses to a somatic inflammatory pain, in marked contrast with the wild-type mice in which long-lasting effects of descending antinociceptive pathway were predominant. These results suggest that the alpha(1E) Ca(2 +) channel controls pain behaviors by both spinal and supraspinal mechanisms.
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Affiliation(s)
- H Saegusa
- Department of Pharmacology and Neurobiology, Graduate School of Medicine, Tokyo Medical and Dental University, and CREST, Japan
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21
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Pisano ED, Zong S, Hemminger BM, DeLuca M, Johnston RE, Muller K, Braeuning MP, Pizer SM. Contrast limited adaptive histogram equalization image processing to improve the detection of simulated spiculations in dense mammograms. J Digit Imaging 1998; 11:193-200. [PMID: 9848052 PMCID: PMC3453156 DOI: 10.1007/bf03178082] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The purpose of this project was to determine whether Contrast Limited Adaptive Histogram Equalization (CLAHE) improves detection of simulated spiculations in dense mammograms. Lines simulating the appearance of spiculations, a common marker of malignancy when visualized with masses, were embedded in dense mammograms digitized at 50 micron pixels, 12 bits deep. Film images with no CLAHE applied were compared to film images with nine different combinations of clip levels and region sizes applied. A simulated spiculation was embedded in a background of dense breast tissue, with the orientation of the spiculation varied. The key variables involved in each trial included the orientation of the spiculation, contrast level of the spiculation and the CLAHE settings applied to the image. Combining the 10 CLAHE conditions, 4 contrast levels and 4 orientations gave 160 combinations. The trials were constructed by pairing 160 combinations of key variables with 40 backgrounds. Twenty student observers were asked to detect the orientation of the spiculation in the image. There was a statistically significant improvement in detection performance for spiculations with CLAHE over unenhanced images when the region size was set at 32 with a clip level of 2, and when the region size was set at 32 with a clip level of 4. The selected CLAHE settings should be tested in the clinic with digital mammograms to determine whether detection of spiculations associated with masses detected at mammography can be improved.
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Affiliation(s)
- E D Pisano
- Department of Radiology, The University of North Carolina, Chapel Hill 27599-7510, USA
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22
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Pisano E, Hemminger B, Zong S, Garrett W, Johnston R, Glueck D, Muller K, Braeuning M, Puff D, Pizer S. Does clahe image processing improve the detectability of simulated spiculations in dense breasts in a laboratory setting? Acad Radiol 1996. [DOI: 10.1016/s1076-6332(96)80109-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [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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Abstract
GH3 cell lines stably expressing alpha 1E channel were established and the modulation of this channel by G-protein through membrane-delimited pathways was studied. Alpha 1E channel expressed in GH3 cells showed slowing of activation and reduction of current amplitude by the application of carbachol or somatostatin. Both of these effects caused by these agents were pertussis toxin (PTX) sensitive and voltage dependent. Dialysis of the cell interior with GTP gamma S mimicked the action of these externally applied neurotransmitters, indicating that the alpha 1E channel is modulated by the PTX sensitive G-protein(s) through the membrane-delimited pathway but not by the PTX insensitive pathway that has been observed in alpha 1A channel expressed in GH3 cells. Thus different types of neuronal Ca2+ channels can be modulated not only by a similar mechanism but also by a different mechanism conferring a multilateral regulation of Ca2+ entry through these channels.
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Affiliation(s)
- M Yassin
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA
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24
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Abstract
GH3 cell lines stably expressing alpha 1A channel were established and the modulation of this channel by G-protein through membrane-delimited pathways were studied. Wild type GH3 cells were found to express omega-conotoxin MVIIC (MVIIC) sensitive Ca2+ current but this component was different from the alpha 1A channel because of its susceptibility to G-protein modulation, suggesting MVIIC also blocks channels other than P/Q type. Alpha 1A channel expressed in GH3 cells showed slowing of activation and reduction of current amplitude by the application of carbachol. Both of these effects were pertussis toxin (PTX) sensitive and voltage dependent. alpha 1A channels were also found to be modulated through a PTX insensitive pathway, the modulations observed were similar to those in the PTX sensitive pathway. The results further suggest that these two effects are governed by a different mechanism in both PTX sensitive and insensitive pathways.
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Affiliation(s)
- S Zong
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812, USA
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25
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Abstract
Modulation of voltage-gated Ca2+ channels by the receptor coupled GTP-binding proteins (G-proteins) is essential for controlling secretion and muscle contraction. We have expressed cloned Ca2+ channels in dysgenic myotubes to study G-protein modulation through the membrane-delimited pathway. The results obtained by the expression of alpha 1B channels and mutant channels of alpha 1B suggest that the two effects observed in G-protein modulated N-type channels (depression of current and slowing of activation) are through two independent mechanisms. In addition, neither the region linking repeat II and III nor carboxy-terminal region, which were demonstrated in L-type channels to determine some of their specific functions, are directly involved in G-protein modulation. The results obtained by the expression of the alpha 1A channel suggest that this channel is modulated through a novel membrane-delimited pathway that may not involve G-protein activation.
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Affiliation(s)
- J Zhou
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812
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26
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Abstract
We investigated the nature and structural requirements for Ca(2+)-dependent inactivation of cardiac L-type Ca2+ channel. Investigation of subunit requirements indicates that the interaction of alpha 1 subunit with ancillary subunits, especially beta subunit, is important for this property. Replacement of the putative cytoplasmic regions of the cardiac alpha 1 subunit with skeletal muscle counterparts eliminates Ca(2+)-dependent inactivation, indicating that the site regulated by Ca2+ resides in the cytoplasmic region of the alpha 1 subunit. Deletion of the carboxy-terminal region of the cardiac alpha 1 subunit does not eliminate this property, suggesting that the modulation by protein kinase A may not be involved in this mechanism. Single amino acid substitution that strongly reduces Ca2+ selectivity of Ca2+ channels also eliminates Ca(2+)-dependent inactivation, suggesting the close link between the ion selectivity and Ca(2+)-dependent inactivation.
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Affiliation(s)
- S Zong
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06536-0812
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