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Yen WC, Li QZ, Wu LH, Lee WY, Chang WW, Chien PJ, Lee CH. Salmonella inhibits tumor metastasis by downregulating epithelial cell adhesion molecules through the protein kinase-B/mammalian target of rapamycin signaling pathway. Int J Biol Macromol 2023; 253:126913. [PMID: 37716656 DOI: 10.1016/j.ijbiomac.2023.126913] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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] [Received: 05/05/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/18/2023]
Abstract
Epithelial cell adhesion molecules (EpCAM) are highly expressed in many carcinomas and regulate the epithelial-mesenchymal transition, which is required for tumor metastasis. Furthermore, EpCAM overexpression induces tumor cells to develop a stem cell-like phenotype and promotes tumor progression. Targeting EpCAM may be a promising approach for inhibiting tumor metastasis and progression. Salmonella treatment suppresses tumor growth and reduces metastatic nodules in tumor-bearing mice. Based on these results, we hypothesized that Salmonella-based treatments could inhibit the expression of metastasis-associated proteins. The dose-dependent Salmonella treatment significantly downregulated the levels of EpCAM and decreased the phosphorylation of protein kinase-B (AKT)/mTOR (mammalian target of rapamycin) pathway, as shown by immunoblotting. In addition, Salmonella treatment increased the levels of epithelial markers and decreased the levels of mesenchymal markers in a dose-dependent manner. Wound-healing and Transwell assays showed that Salmonella treatment significantly reduced tumor cell migration. The mice were intravenously injected with B16F10 and CT26 cells pre-incubated with or without Salmonella, and the survival of tumor-bearing mice in the Salmonella group increased, indicating an antimetastatic effect. Our findings demonstrate that Salmonella plays a role in inhibiting tumor metastasis by downregulating EpCAM via the AKT/mTOR signaling pathway and has great potential for cancer therapy.
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Affiliation(s)
- Wei-Che Yen
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Qiao-Zhu Li
- Department of Surgery, Kaohsiung Armed Forces General Hospital, Kaohsiung 80284, Taiwan
| | - Li-Hsien Wu
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Wei-Ya Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Wen-Wei Chang
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402306, Taiwan
| | - Peng-Ju Chien
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung City 402306, Taiwan
| | - Che-Hsin Lee
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; School of Medicine, College of Medicine, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; International PhD Program for Science, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung 80424, Taiwan.
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Lee YH, Yang YL, Yen WC, Su WF, Dai CA. Solution self-assembly and phase transformations of form II crystals in nanoconfined poly(3-hexyl thiophene) based rod-coil block copolymers. Nanoscale 2014; 6:2194-2200. [PMID: 24382571 DOI: 10.1039/c3nr04214f] [Citation(s) in RCA: 19] [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] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Solution processing of π-conjugated polymers constitutes a major low-cost manufacturing method for the fabrication of many new organic optoelectronic devices. The solution self-assembly kinetics of π-conjugated rod-coil block copolymers of symmetric poly(3-hexyl thiophene)-b-poly(2-vinyl pyridine) (P3HT-P2VP) during drying and the phase transformations of the subsequently dried samples were studied by using a combination of TEM, SAXS, WAXS and DSC measurements. During solution drying in chlorobenzene, a good solvent for the copolymer, P3HT-P2VP first formed nanoseed aggregates followed by the directional growth of nanofibrils driven by the formation of prevailing form II P3HT crystals within its nanofibril core confined by the surrounding domain of P2VP blocks. This result was in sharp contrast when a similar molecular weight P3HT homopolymer was solution self-assembled in chlorobenzene, nearly free from confinement, in which case the resulting nanofibrils consisted of a mixture of majority form I and form II crystals. Solvent-cast films of P3HT-P2VP nanofibrils with form II crystals were heat-/cold-treated and showed solid-state phase transformations from form II crystals to form I crystals, both within nanofibrils with annealing, indicating the metastability of the form II crystals with temperature. A disordered state followed with increasing temperatures which, when cooled, induced the formation of a thermodynamically stable lamellar phase with only form I P3HT crystals. Correspondingly, the study provides new strategies for controlling polymorphs and nanostructures of π-conjugated block copolymers for future applications using solution processing and subsequent heat treatment.
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Affiliation(s)
- Yi-Huan Lee
- Department of Chemical Engineering, National Taiwan University, No. 1, Roosevelt Rd. Sec. 4, Taipei 106, Taiwan.
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Lin JF, Tu GY, Ho CC, Chang CY, Yen WC, Hsu SH, Chen YF, Su WF. Molecular structure effect of pyridine-based surface ligand on the performance of P3HT:TiO₂ hybrid solar cell. ACS Appl Mater Interfaces 2013; 5:1009-1016. [PMID: 23323972 DOI: 10.1021/am302700c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Colloid TiO(2) nanorods are used for solution-processable poly(3-hexyl thiophene): TiO(2) hybrid solar cell. The nanorods were covered by insulating ligand of oleic acid (OA) after sol-gel synthesis. Three more conducting pyridine type ligands: pyridine, 2,6-lutidine (Lut) and 4-tert-butylpyridine (tBP) were investigated respectively to replace OA. The power conversion efficiency (PCE) of the solar cell was increased because the electronic mobility of pyridine-type ligand-modified TiO(2) is higher than that of TiO(2)-OA. The enhancement of PCE is in the descending order of Lut > pyridine > tBP because of the effective replacement of OA by Lut. The PCE of solar cell can be further enhanced by ligand exchange of pyridine type ligand with conjugating molecule of 2-cyano-3-(5-(7-(thiophen-2-yl)-benzothiadiazol-4-yl) thiophen-2-yl) acrylic acid (W4) on TiO(2) nanorods because W4 has aligned bandgap with P3HT and TiO(2) to facilitate charge separation and transport. The electronic mobility of two-stage ligand exchanged TiO(2) is improved furthermore except Lut, because it adheres well and difficult to be replaced by W4. The amount of W4 on TiO(2)-tBP is 3 times more than that of TiO(2)-Lut (0.20 mol % vs. 0.06 mol %). Thus, the increased extent of PCE of solar cell is in the decreasing order of tBP > pyridine > Lut. The TiO(2)-tBP-W4 device has the best performance with 1.4 and 2.6 times more than TiO(2)-pyridine-W4 and TiO(2)-Lut-W4 devices, respectively. The pKa of the pyridine derivatives plays the major role to determine the ease of ligand exchange on TiO(2) which is the key factor mandating the PCE of P3HT:TiO(2) hybrid solar cell. The results of this study provide new insights of the significance of acid-base reaction on the TiO(2) surface for TiO(2)-based solar cells. The obtained knowledge can be extended to other hybrid solar cell systems.
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Affiliation(s)
- Jhih-Fong Lin
- Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan
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Yen WC, Lee YH, Lin JF, Dai CA, Jeng US, Su WF. Effect of TiO2 nanoparticles on self-assembly behaviors and optical and photovoltaic properties of the P3HT-b-P2VP block copolymer. Langmuir 2011; 27:109-115. [PMID: 21141849 DOI: 10.1021/la103972j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An ordered nanostructure can be created from the hybrid materials of self-assembly poly(3-hexyl thiophene-b-2-vinyl pyridine) and nicotinic acid-modified titanium dioxide nanoparticles (P3HT-b-P2VP/TiO(2)). TEM and XRD analyses reveal that the TiO(2) nanoparticles (NPs) are preferentially confined in the P2VP domain of P3HT-b-P2VP whereas TiO(2) NPs interact with either pure P3HT or a blend of P3HT and P2VP to produce microsized phase segregation. The morphologies of lamellar and cylindrical structures are disturbed when the loading of TiO(2) NPs is 40 wt % or higher. Cylindrical P3HT-b-P2VP/TiO(2) exhibits a small blue shift in absorption and photoluminescence spectra with increasing TiO(2) loading as compared to P3HT/TiO(2). The NPs cause a slightly misaligned P3HT domain in the copolymer. Furthermore, the PL quenching of P3HT-b-P2VP/TiO(2) becomes very large as a result of efficient charge separation in the ordered nanodomain at 16 nm. Solar cells fabricated from self-assembly P3HT-b-P2VP/TiO(2) hybrid materials exhibit a >30 fold improvement in power conversion efficiency as compared to the corresponding 0.3P3HT-0.7P2VP/TiO(2) polymer blend hybrid. This study paves the way for the further development of high-efficiency polymer-inorganic nanoparticle hybrid solar cells using a self-assembled block copolymer.
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Affiliation(s)
- Wei-Che Yen
- Institute of Polymer Science and Engineering, National Taiwan University, Taipei, Taiwan
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Huang YC, Hsu JH, Liao YC, Yen WC, Li SS, Lin ST, Chen CW, Su WF. Employing an amphiphilic interfacial modifier to enhance the performance of a poly(3-hexyl thiophene)/TiO2 hybrid solar cell. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c0jm03615c] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Wu MC, Wu YJ, Yen WC, Lo HH, Lin CF, Su WF. Correlation between nanoscale surface potential and power conversion efficiency of P3HT/TiO2 nanorod bulk heterojunction photovoltaic devices. Nanoscale 2010; 2:1448-1454. [PMID: 20820733 DOI: 10.1039/b9nr00385a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This is an in depth study on the surface potential changes of P3HT/TiO(2) nanorod bulk heterojunction thin films. They are affected by interlayer structures, the molecular weight of P3HT, the processing solvents and the surface ligands on the TiO(2). The addition of an electron blocking layer and/or the hole blocking layer to the P3HT/TiO(2) thin film can facilitate charge carrier transport and result in a high surface potential shift. The changes in surface potential of multilayered bulk heterojunction films are closely correlated to their power conversion efficiency of photovoltaic devices. Changing ligand leads to the largest change in surface potential yielding the greatest effect on the power conversion efficiency. Merely changing the P3HT molecular weight is less effective and varying the processing solvents is least effective in increasing power conversion efficiency. The steric effect of the ligand has a large influence on the reduction of charge carrier recombination resulting in a great effect on the power conversion efficiency. By monitoring the changes in the surface potential of bulk heterojunction film of multilayer structures, we have obtained a useful guide for the fabrication of high performance photovoltaic devices.
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Affiliation(s)
- Ming-Chung Wu
- Department of Materials Science and Engineering, National Taiwan University, Taipei, 106-17, Taiwan
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Wu MC, Liao HC, Chou Y, Hsu CP, Yen WC, Chuang CM, Lin YY, Chen CW, Chen YF, Su WF. Manipulation of Nanoscale Phase Separation and Optical Properties of P3HT/PMMA Polymer Blends for Photoluminescent Electron Beam Resist. J Phys Chem B 2010; 114:10277-84. [DOI: 10.1021/jp1009059] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ming-Chung Wu
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Hsueh-Chung Liao
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Yi Chou
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Che-Pu Hsu
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Wei-Che Yen
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Chih-Min Chuang
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Yun-Yue Lin
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Chun-Wei Chen
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Yang-Fang Chen
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
| | - Wei-Fang Su
- Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Polymer Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan; Institute of Nuclear Energy Research, Atomic Energy Council, Taiyuan 325-46, Taiwan; and Department of Physics, National Taiwan University, Taipei 106-17, Taiwan
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Huang YP, Chang HL, Huang YJ, Chang YT, Su KW, Yen WC, Chen YF. Subnanosecond mJ eye-safe laser with an intracavity optical parametric oscillator in a shared resonator. Opt Express 2009; 17:1551-1556. [PMID: 19188984 DOI: 10.1364/oe.17.001551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We theoretically verify that the threshold of an intracavity optical parametric oscillator pumped by a passively Q-switched laser is entirely controlled by the bleach of the saturable absorber not by the signal output reflectivity. We use a series of different output couplers to optimize the output performance. With a signal output reflectivity of 15%, we experimentally achieve an efficient subnanosecond eye-safe laser with 3.3 mJ pulse energy and 1.5 MW peak power.
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Affiliation(s)
- Y P Huang
- Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
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Pal B, Yen WC, Yang JS, Chao CY, Hung YC, Lin ST, Chuang CH, Chen CW, Su WF. Substituent Effect on the Optoelectronic Properties of Alternating Fluorene−Cyclopentadithiophene Copolymers. Macromolecules 2008. [DOI: 10.1021/ma800362n] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bikash Pal
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Wei-Che Yen
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Jye-Shane Yang
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chi-Yang Chao
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Ying-Chieh Hung
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Shiang-Tai Lin
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chia-Hao Chuang
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Chun-Wei Chen
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
| | - Wei-Fang Su
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, Department of Chemistry, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan
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Wu MC, Chang CH, Lo HH, Lin YS, Lin YY, Yen WC, Su WF, Chen YF, Chen CW. Nanoscale morphology and performance of molecular-weight-dependent poly(3-hexylthiophene)/TiO2 nanorod hybrid solar cells. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b803484b] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Affiliation(s)
- Bikash Pal
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, and Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Wei-Che Yen
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, and Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Jye-Shane Yang
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, and Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Wei-Fang Su
- Department of Material Science and Engineering, Institute of Polymer Science and Engineering, and Department of Chemistry, National Taiwan University, Taipei, Taiwan
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Dai CA, Yen WC, Lee YH, Ho CC, Su WF. Facile Synthesis of Well-Defined Block Copolymers Containing Regioregular Poly(3-hexyl thiophene) via Anionic Macroinitiation Method and Their Self-Assembly Behavior. J Am Chem Soc 2007; 129:11036-8. [PMID: 17696540 DOI: 10.1021/ja0733991] [Citation(s) in RCA: 231] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chi-An Dai
- Institute of Polymer Science and Engineering, Department of Chemical Engineering, National Taiwan University, Taipei, 106 Taiwan.
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Chen YF, Su KW, Chang YT, Yen WC. Compact efficient eye-safe intracavity optical parametric oscillator with a shared cavity configuration. Appl Opt 2007; 46:3597-601. [PMID: 17514321 DOI: 10.1364/ao.46.003597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We present a compact efficient eye-safe intracavity optical parametric oscillator pumped by a passively Q-switched Nd:YAG laser in a shared cavity configuration. A signal pulse of 3.3 mJ energy at a 1573 nm wavelength with a peak power of 150 kW was achieved. The effective conversion efficiency with respective to the optimized 1064 nm Q-switched pulse energy was as high as 51%.
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Affiliation(s)
- Y F Chen
- Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan.
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Abstract
Several interspecific combinations of the "elegans" group of Caenorhabditis species are cross-fertile. Most F1 hybrids from these crosses arrest during embryogenesis. Developmental defects observed in hybrid embryos include defects in gastrulation initiation, defects in embryonic compaction, and defects in embryonic elongation. These reproductive barriers have arisen multiple times in the evolution of Caenorhabditis.
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Affiliation(s)
- S E Baird
- Department of Biological Sciences, Wright State University, Dayton, OH 45435, USA.
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Affiliation(s)
- W C Yen
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Ohio State University, Columbus 43210, USA
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Abstract
PURPOSE Previous studies by other investigators have shown an enhancement of mitomycin C (MMC) activity at acidic extracellular pH (pHe) in monolayer cultures of human cells. The goal of the present study was to determine if the efficacy of intravesical MMC therapy in patients treated for superficial bladder cancer can be enhanced by using acidified dosing solutions. We evaluated (a) the effect of pHe on MMC activity in patient bladder tumors in vitro, and (b) the pH dependency of MMC activity in 2-dimensional monolayer and 3-dimensional multilayer cultures of human bladder RT4 tumor cells. METHODS Patient bladder tumors were maintained as 3-dimensional histocultures. RT4 cells were harvested and maintained as monolayer cultures or as 3-dimensional cell pellets on a collagen gel matrix. The cell pellets were 300-450 cell layers and 4,000-5,000 microns in diameter. Tumors or cells were incubated for 2 hr with MMC-containing media at pHe of 5, 6, and 7.4. The drug effect was measured by the inhibition of DNA precursor (thymidine) incorporation. The stability of MMC as a function of pHe was determined. About 24% of MMC was degraded following 2 hr exposure at pHe 5 and < or = 2% at pHe 6 and 7.4. RESULTS The drug concentrations required to inhibit thymidine incorporation by 50% (IC50) were corrected for the degraded MMC at acidic pHe. The results showed no pH-dependent MMC activity in human patient bladder tumors nor in RT4 multilayer cultures; the IC50 values were about 10 micrograms/ml at all three pHe. In contrast, the monolayer RT4 cultures showed a pH-dependent MMC cytotoxicity; the IC50 were 0.1, 0.8 and 1.2 micrograms/ ml at pHe 5, 6 and 7.4, respectively (p < 0.05). Pre-incubation of multilayered RT4 cultures in acidic pH medium for 8 hr enhanced the MMC activity; the IC50 was reduced by about 5 fold at pHe about 3 fold at pHe 6. Similar pH-dependent MMC activity was found when multilayers were pre-treated for 1 hr with 0.5 microgram/ml nigericin, a proton ionophore known to cause the intracellular pH (pHi) to equilibrate with pHe. CONCLUSIONS These data suggest that the difference in the pH dependency of MMC activity in the monolayer and multilayer systems was due to the different experimental conditions. The time lag for pHi to equilibrate with pHe in the multilayer systems and the instability of MMC at low pHe imply that the efficacy of intravesical MMC therapy is unlikely to be enhanced by using acidic dosing solution.
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Affiliation(s)
- W C Yen
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Ohio State University, Columbus 43210, USA
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Abstract
PURPOSE This study compared the sensitivity of rat prostate MAT-LyLu primary and lymph node metastatic tumors to taxol. METHODS Tumors were established by subcutaneous implantation of tumor cells in a hind leg (primary site) of male Copenhagen rats. Lymph node metastases were used for serial transplantation. Eleven pairs of primary and metastatic tumors between the sixth and twentieth generations were harvested and maintained as 3-dimensional histocultures. The effects of taxol (24 hr treatment at 1 nM to 10 microM) were measured by the appearance of apoptotic cells, and by the inhibition of DNA precursor (thymidine) incorporation. To determine the basis of differential sensitivity of primary and metastatic tumors to the DNA inhibition, we examined the expression of multidrug resistance pglycoprotein (Pgp) and the accumulation of 3H-taxol after 24 hr exposure and the retention after a 48 hr washout period. RESULTS The fraction of apoptotic cells increased linearly with the logarithm of taxol concentration to a maximal value of 25%; the concentration-response curves for primary and metastatic tumors were superimposable. Taxol produced a sigmoidal, concentration-dependent inhibition of thymidine incorporation; the maximal inhibition of approximately 40% was reached at 0.1 and 1 microM for primary and metastatic tumors, respectively. Within the primary or metastatic subgroups, the IC30 (drug concentration that produced a 30% inhibition of DNA synthesis) among consecutive generations varied by < 5 fold, but the primary tumor consistently showed a lower IC30 than the daughter or the parent metastatic tumor (mean, 20-fold; median, 15-fold; range, 6- to 56-fold). The finding that the lower drug sensitivity in metastatic tumors was not exhibited in its daughter primary tumor but was regained in its daughter metastatic tumors suggests that the chemoresistant phenotype is maintained only in lymph nodes and not in the primary site. There were no differences in the Pgp status (neither tumor expressed Pgp), accumulation and retention of taxol in primary and metastatic tumors. CONCLUSIONS Taxol induced apoptosis and inhibited DNA synthesis in the rat MAT-LyLu primary and lymph node metastatic tumors. The apoptotic effect was not different among the two tumors, whereas the primary tumor was more sensitive to the inhibition of DNA synthesis. The differential sensitivity of the two tumors to the DNA effect is not associated with a difference in Pgp expression, drug accumulation nor drug retention, and appears to be associated with changes that are linked to lymph node metastasis.
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Affiliation(s)
- W C Yen
- Division of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, Ohio State University, Columbus, USA
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Yen WC, Lee VH. Role of Na+ in the asymmetric paracellular transport of 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg across rabbit colonic segments and Caco-2 cell monolayers. J Pharmacol Exp Ther 1995; 275:114-9. [PMID: 7562538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
This study was conducted to demonstrate that Na+ played a role in the paracellular transport of 4-phenylazobenzyloxycarbonyl-L-Pro-L-Leu-Gly-L-Pro-D-Arg (Pz-peptide), a hydrophilic proline-containing pentapeptide, across the rabbit colonic mucosa and Caco-2 cell monolayers. Over the 1 to 5 mM concentration range, Pz-peptide transport was 25 to 180 times greater from the mucosal-to-serosal than from the opposite direction. This asymmetry in transport was consistent with the ability of Pz-peptide to lower the transepithelial electrical resistance of Caco-2 cell monolayers only from the mucosal side. Blockade of Na+ access to the apically located amiloride-sensitive Na+ channel in the lower intestinal segments by mucosal 10 microM amiloride, serosal 100 microM ouabain or removal of Na+ ions in the mucosal fluid dramatically reduced Pz-peptide transport to 5% of the control. Moreover, Pz-peptide transport across Caco-2 cell monolayers could be titrated against mucosal Na+ concentration. There was a small mucosal-to-serosal solvent drag effect induced by transepithelial Na+ flux stimulated by Pz-peptide in the colon, contributing in part to enhanced paracellular solute transport. Overall, the above findings are consistent with a scenario whereby Pz-peptide stimulates transepithelial Na+ flux across the colonic segments at the level of the amiloride-sensitive Na+ channel, thereby triggering yet to be identified intracellular biochemical changes that ultimately result in tight junctional opening and enhanced paracellular solute transport.
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Affiliation(s)
- W C Yen
- University of Southern California, School of Pharmacy, Department of Pharmaceutical Sciences, Los Angeles
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