51
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Liu M, Little MA, Jelfs KE, Jones JTA, Schmidtmann M, Chong SY, Hasell T, Cooper AI. Acid- and Base-Stable Porous Organic Cages: Shape Persistence and pH Stability via Post-synthetic “Tying” of a Flexible Amine Cage. J Am Chem Soc 2014; 136:7583-6. [DOI: 10.1021/ja503223j] [Citation(s) in RCA: 158] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Ming Liu
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Marc A. Little
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Kim E. Jelfs
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - James T. A. Jones
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Marc Schmidtmann
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Samantha Y. Chong
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Tom Hasell
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Andrew I. Cooper
- Department
of Chemistry and
Centre for Materials Discovery, University of Liverpool, Liverpool L69 7ZD, U.K
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52
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Szczecinski R, Chong SY, Chater PA, Hughes H, Tucker MG, Claridge JB, Rosseinsky MJ. Local Crystal Structure of Antiferroelectric Bi 2Mn 4/3Ni 2/3O 6 in Commensurate and Incommensurate Phases Described by Pair Distribution Function (PDF) and Reverse Monte Carlo (RMC) Modeling. Chem Mater 2014; 26:2218-2232. [PMID: 25673920 PMCID: PMC4311938 DOI: 10.1021/cm4038439] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 02/20/2014] [Indexed: 06/04/2023]
Abstract
The functional properties of materials can arise from local structural features that are not well determined or described by crystallographic methods based on long-range average structural models. The room temperature (RT) structure of the Bi perovskite Bi2Mn4/3Ni2/3O6 has previously been modeled as a locally polar structure where polarization is suppressed by a long-range incommensurate antiferroelectric modulation. In this study we investigate the short-range local structure of Bi2Mn4/3Ni2/3O6, determined through reverse Monte Carlo (RMC) modeling of neutron total scattering data, and compare the results with the long-range incommensurate structure description. While the incommensurate structure has equivalent B site environments for Mn and Ni, the local structure displays a significantly Jahn-Teller distorted environment for Mn3+. The local structure displays the rock-salt-type Mn/Ni ordering of the related Bi2MnNiO6 high pressure phase, as opposed to Mn/Ni clustering observed in the long-range average incommensurate model. RMC modeling reveals short-range ferroelectric correlations between Bi3+ cations, giving rise to polar regions that are quantified for the first time as existing within a distance of approximately 12 Å. These local correlations persist in the commensurate high temperature (HT) phase, where the long-range average structure is nonpolar. The local structure thus provides information about cation ordering and B site structural flexibility that may stabilize Bi3+ on the A site of the perovskite structure and reveals the extent of the local polar regions created by this cation.
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Affiliation(s)
| | - Samantha Y. Chong
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Philip A. Chater
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Helen Hughes
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Matthew G. Tucker
- ISIS
Facility, Rutherford Appleton Laboratory, Harwell, Didcot OX11 0DE, U.K.
| | - John B. Claridge
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
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53
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Hasell T, Culshaw JL, Chong SY, Schmidtmann M, Little MA, Jelfs KE, Pyzer-Knapp EO, Shepherd H, Adams DJ, Day GM, Cooper AI. Controlling the Crystallization of Porous Organic Cages: Molecular Analogs of Isoreticular Frameworks Using Shape-Specific Directing Solvents. J Am Chem Soc 2014; 136:1438-48. [DOI: 10.1021/ja409594s] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Tom Hasell
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Jamie L. Culshaw
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Samantha Y. Chong
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Marc Schmidtmann
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Marc A. Little
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Kim E. Jelfs
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Edward O. Pyzer-Knapp
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Hilary Shepherd
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Dave J. Adams
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
| | - Graeme M. Day
- School
of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, United Kingdom
| | - Andrew I. Cooper
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown St., Liverpool L69
7ZD, United Kingdom
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54
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Pyzer-Knapp EO, Thompson HPG, Schiffmann F, Jelfs KE, Chong SY, Little MA, Cooper AI, Day GM. Predicted crystal energy landscapes of porous organic cages. Chem Sci 2014. [DOI: 10.1039/c4sc00095a] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Computational methods predict the crystal packing of porous organic cage molecules, allowing crystal structure and porosity to be predicted starting from the chemical diagram alone.
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Affiliation(s)
| | | | | | - Kim E. Jelfs
- Department of Chemistry
- Imperial College London
- London, UK
| | - Samantha Y. Chong
- Department of Chemistry and Centre for Materials Discovery
- University of Liverpool
- Liverpool, UK
| | - Marc A. Little
- Department of Chemistry and Centre for Materials Discovery
- University of Liverpool
- Liverpool, UK
| | - Andrew I. Cooper
- Department of Chemistry and Centre for Materials Discovery
- University of Liverpool
- Liverpool, UK
| | - Graeme M. Day
- School of Chemistry
- University of Southampton
- Southampton, UK
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55
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Jiang S, Jelfs KE, Holden D, Hasell T, Chong SY, Haranczyk M, Trewin A, Cooper AI. Molecular Dynamics Simulations of Gas Selectivity in Amorphous Porous Molecular Solids. J Am Chem Soc 2013; 135:17818-30. [DOI: 10.1021/ja407374k] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Shan Jiang
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Kim E. Jelfs
- Department
of Chemistry, Imperial College London, South Kensington, London, SW7 2AZ, U.K
| | - Daniel Holden
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Tom Hasell
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Samantha Y. Chong
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Maciej Haranczyk
- Computational
Research Division, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, United States
| | - Abbie Trewin
- Department
of Chemistry, Lancaster University, Bailrigg, Lancaster, LA1 4YB, U.K
| | - Andrew I. Cooper
- Department
of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
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56
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Blanc F, Chong SY, McDonald TO, Adams DJ, Pawsey S, Caporini MA, Cooper AI. Dynamic nuclear polarization NMR spectroscopy allows high-throughput characterization of microporous organic polymers. J Am Chem Soc 2013; 135:15290-3. [PMID: 24028380 DOI: 10.1021/ja408074v] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Dynamic nuclear polarization (DNP) solid-state NMR was used to obtain natural abundance (13)C and (15)N CP MAS NMR spectra of microporous organic polymers with excellent signal-to-noise ratio, allowing for unprecedented details in the molecular structure to be determined for these complex polymer networks. Sensitivity enhancements larger than 10 were obtained with bis-nitroxide radical at 14.1 T and low temperature (∼105 K). This DNP MAS NMR approach allows efficient, high-throughput characterization of libraries of porous polymers prepared by combinatorial chemistry methods.
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Affiliation(s)
- Frédéric Blanc
- Department of Chemistry, §Stephenson Institute for Renewable Energy, and ‡Center for Materials Discovery, University of Liverpool , Crown Street, Liverpool L69 7ZD, United Kingdom
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57
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Chong SY, Hasell T, Briggs ME, Jelfs KE, Little MA, Schmidtmann M, Cooper AI. Assembling pore networks in organic cage structures using molecular recognition. Acta Crystallogr A 2013. [DOI: 10.1107/s0108767313097973] [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: 11/10/2022] Open
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58
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59
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Stylianou KC, Rabone J, Chong SY, Heck R, Armstrong J, Wiper PV, Jelfs KE, Zlatogorsky S, Bacsa J, McLennan AG, Ireland CP, Khimyak YZ, Thomas KM, Bradshaw D, Rosseinsky MJ. Dimensionality transformation through paddlewheel reconfiguration in a flexible and porous Zn-based metal-organic framework. J Am Chem Soc 2012; 134:20466-78. [PMID: 23121122 DOI: 10.1021/ja308995t] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The reaction between Zn and a pyrene-based ligand decorated with benzoate fragments (H(4)TBAPy) yields a 2D layered porous network with the metal coordination based on a paddlewheel motif. Upon desolvation, the structure undergoes a significant and reversible structural adjustment with a corresponding reduction in crystallinity. The combination of computationally assisted structure determination and experimental data analysis of the desolvated phase revealed a structural change in the metal coordination geometry from square-pyramidal to tetrahedral. Simulations of desolvation showed that the local distortion of the ligand geometry followed by the rotation and displacement of the pyrene core permits the breakup of the metal-paddlewheel motifs and the formation of 1D Zn-O chains that cross-link adjacent layers, resulting in a dimensionality change from the 2D layered structure to a 3D structure. Constrained Rietveld refinement of the powder X-ray diffraction pattern of the desolvated phase and the use of other analytical techniques such as porosity measurements, (13)C CP MAS NMR spectroscopy, and fluorescence spectroscopy strongly supported the observed structural transformation. The 3D network is stable up to 425 °C and is permanently porous to CO(2) with an apparent BET surface area of 523(8) m(2)/g (p/p° = 0.02-0.22). Because of the hydrophobic nature, size, and shape of the pores of the 3D framework, the adsorption behavior of the structure toward p-xylene and m-xylene was studied, and the results indicated that the shape of the isotherm and the kinetics of the adsorption process are determined mainly by the shape of the xylene isomers, with each xylene isomer interacting with the host framework in a different manner.
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60
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61
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62
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Chong SY, Szczecinski RJ, Bridges CA, Tucker MG, Claridge JB, Rosseinsky MJ. Local Structure of a Pure Bi A Site Polar Perovskite Revealed by Pair Distribution Function Analysis and Reverse Monte Carlo Modeling: Correlated Off-Axis Displacements in a Rhombohedral Material. J Am Chem Soc 2012; 134:5836-49. [PMID: 22356424 DOI: 10.1021/ja210698e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Samantha Y. Chong
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | | | - Craig A. Bridges
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Matthew G. Tucker
- ISIS Facility, Rutherford Appleton Laboratory, Harwell, Didcot OX11
0DE, U.K
| | - John B. Claridge
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
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63
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Abstract
We present here a simple method for the bottom-up fabrication of microporous organic particles with surface areas in the range 500-1000 m(2) g(-1). The method involves chiral recognition between prefabricated, intrinsically porous organic cage molecules that precipitate spontaneously upon mixing in solution. Fine control over particle size from 50 nm to 1 μm can be achieved by varying the mixing temperature or the rate of mixing. No surfactants or templates are required, and the resulting organic dispersions are stable for months. In this method, the covalent synthesis of the cage modules can be separated from their solution processing into particles because the modules can be dissolved in common solvents. This allows a "mix and match" approach to porous organic particles. The marked solubility change that occurs upon mixing cages with opposite chirality is rationalized by density functional theory calculations that suggest favorable intermolecular interactions for heterochiral cage pairings. The important contribution of molecular disorder to porosity and surface area is highlighted. In one case, a purposefully amorphized sample has more than twice the surface area of its crystalline analogue.
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Affiliation(s)
- Tom Hasell
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
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64
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Bojdys MJ, Briggs ME, Jones JTA, Adams DJ, Chong SY, Schmidtmann M, Cooper AI. Supramolecular Engineering of Intrinsic and Extrinsic Porosity in Covalent Organic Cages. J Am Chem Soc 2011; 133:16566-71. [DOI: 10.1021/ja2056374] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [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)
- Michael J. Bojdys
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Michael E. Briggs
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - James T. A. Jones
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Dave J. Adams
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Samantha Y. Chong
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Marc Schmidtmann
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
| | - Andrew I. Cooper
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K
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65
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Jones JTA, Hasell T, Wu X, Bacsa J, Jelfs KE, Schmidtmann M, Chong SY, Adams DJ, Trewin A, Schiffman F, Cora F, Slater B, Steiner A, Day GM, Cooper AI. Modular and predictable assembly of porous organic molecular crystals. Nature 2011; 474:367-71. [DOI: 10.1038/nature10125] [Citation(s) in RCA: 410] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 04/18/2011] [Indexed: 11/09/2022]
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66
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Stylianou KC, Warren JE, Chong SY, Rabone J, Bacsa J, Bradshaw D, Rosseinsky MJ. CO2 selectivity of a 1D microporous adenine-based metal–organic framework synthesised in water. Chem Commun (Camb) 2011; 47:3389-91. [DOI: 10.1039/c0cc05559j] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [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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67
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Rabone J, Yue YF, Chong SY, Stylianou KC, Bacsa J, Bradshaw D, Darling GR, Berry NG, Khimyak YZ, Ganin AY, Wiper P, Claridge JB, Rosseinsky MJ. An Adaptable Peptide-Based Porous Material. Science 2010; 329:1053-7. [PMID: 20798314 DOI: 10.1126/science.1190672] [Citation(s) in RCA: 294] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- J Rabone
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
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68
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Li MR, Kuang X, Chong SY, Xu Z, Thomas CI, Niu H, Claridge JB, Rosseinsky MJ. Interstitial oxide ion order and conductivity in La1.64Ca0.36Ga3O7.32 melilite. Angew Chem Int Ed Engl 2010; 49:2362-6. [PMID: 20191640 PMCID: PMC3430004 DOI: 10.1002/anie.200906220] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Man-Rong Li
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD UK
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69
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Stylianou KC, Heck R, Chong SY, Bacsa J, Jones JTA, Khimyak YZ, Bradshaw D, Rosseinsky MJ. A Guest-Responsive Fluorescent 3D Microporous Metal−Organic Framework Derived from a Long-Lifetime Pyrene Core. J Am Chem Soc 2010; 132:4119-30. [DOI: 10.1021/ja906041f] [Citation(s) in RCA: 419] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Romain Heck
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | - Samantha Y. Chong
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | - John Bacsa
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | - James T. A. Jones
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
| | | | - Darren Bradshaw
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
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70
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Tozawa T, Jones JTA, Swamy SI, Jiang S, Adams DJ, Shakespeare S, Clowes R, Bradshaw D, Hasell T, Chong SY, Tang C, Thompson S, Parker J, Trewin A, Bacsa J, Slawin AMZ, Steiner A, Cooper AI. Porous organic cages. Nat Mater 2009; 8:973-978. [PMID: 19855385 DOI: 10.1038/nmat2545] [Citation(s) in RCA: 738] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 09/14/2009] [Indexed: 05/28/2023]
Abstract
Porous materials are important in a wide range of applications including molecular separations and catalysis. We demonstrate that covalently bonded organic cages can assemble into crystalline microporous materials. The porosity is prefabricated and intrinsic to the molecular cage structure, as opposed to being formed by non-covalent self-assembly of non-porous sub-units. The three-dimensional connectivity between the cage windows is controlled by varying the chemical functionality such that either non-porous or permanently porous assemblies can be produced. Surface areas and gas uptakes for the latter exceed comparable molecular solids. One of the cages can be converted by recrystallization to produce either porous or non-porous polymorphs with apparent Brunauer-Emmett-Teller surface areas of 550 and 23 m2 g(-1), respectively. These results suggest design principles for responsive porous organic solids and for the modular construction of extended materials from prefabricated molecular pores.
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Affiliation(s)
- Tomokazu Tozawa
- Department of Chemistry and Centre for Materials Discovery, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
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71
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Chong SY, Seaton CC, Kariuki BM, Tremayne M. Molecular versus crystal symmetry in tri-substituted triazine, benzene and isocyanurate derivatives. Acta Crystallogr B Struct Sci 2006; 62:864-74. [PMID: 16983167 DOI: 10.1107/s0108768106020921] [Citation(s) in RCA: 8] [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] [Received: 02/17/2006] [Accepted: 06/01/2006] [Indexed: 11/10/2022]
Abstract
The crystal structures of triethyl-1,3,5-triazine-2,4,6-tricarboxylate (I), triethyl-1,3,5-benzenetricarboxylate (II) and tris-2-hydroxyethyl isocyanurate (III) have been determined from conventional laboratory X-ray powder diffraction data using the differential evolution structure solution technique. The determination of these structures presented an unexpectedly wide variation in levels of difficulty, with only the determination of (III) being without complication. In the case of (I) structure solution resulted in a Rietveld refinement profile that was not ideal, but was subsequently rationalized by single-crystal diffraction as resulting from disorder. Refinement of structure (II) showed significant variation in side-chain conformation from the initial powder structure solution. Further investigation showed that the structure solution optimization had indeed been successful, and that preferred orientation had a dramatic effect on the structure-solution R-factor search surface. Despite the presence of identical side chains in (I) and (II), only the triazine-based system retains threefold molecular symmetry in the crystal structure. The lack of use of the heterocyclic N atom as a hydrogen-bond acceptor in this structure results in the formation of a similar non-centrosymmetric network to the benzene-based structure, but with overall three-dimensional centrosymmetry. The hydrogen-bonded layer structure of (III) is similar to that of other isocyanurate-based structures of this type.
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Affiliation(s)
- Samantha Y Chong
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, England
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72
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Koh ET, Leong KP, Tsou IYY, Lim VH, Pong LY, Chong SY, Seow A. The reliability, validity and sensitivity to change of the Chinese version of SF-36 in oriental patients with rheumatoid arthritis. Rheumatology (Oxford) 2006; 45:1023-8. [PMID: 16495318 DOI: 10.1093/rheumatology/kel051] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [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: 11/14/2022] Open
Abstract
OBJECTIVE To assess the reliability, validity and sensitivity to change of a Chinese version of the 36-item Short-Form Health Survey (SF-36) in Chinese-speaking patients with rheumatoid arthritis (RA) in Singapore. METHODS The psychometric properties of the Chinese Hong Kong standard version of the SF-36 were assessed in 401 RA patients. The construct validity of the Chinese SF-36 was assessed by comparison with the American College of Rheumatology (ACR) functional status, a validated Chinese Health Assessment Questionnaire (C-HAQ) and markers of RA activity and severity. RESULTS The overall Cronbach's coefficient alpha was 0.921, reflecting excellent internal consistency. The instrument showed reasonable test-retest reliability except in the social functioning (SF) subscale. There was a significant ceiling effect in the role physical (RP), SF and role emotional (RE) subscales and a floor effect in the RP and RE subscales. Physical function (PF) and SF were strongly correlated with C-HAQ and patient's assessment of RA activity [Pearson's correlation coefficient (r) ranging from -0.41 to -0.53] and moderately correlated with ACR functional status (r = -0.35 and -0.3, respectively). Weak correlations were also found between the Chinese SF-36 and markers of RA activity, deformed joint count and radiographic damage. PF and SF were the subscales most responsive to change in quality of life (QOL). CONCLUSION The Chinese SF-36 showed reasonable reliability, criterion validity and responsiveness with limitations in certain subscales. Overall, the physical domains and PF in particular may be the most ideal psychometric measures of QOL in RA.
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Affiliation(s)
- E T Koh
- Department of Rheumatology, Allergy and Immunology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433.
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73
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Chong SY, Tremayne M. Combined optimization using cultural and differential evolution: application to crystal structure solution from powder diffraction data. Chem Commun (Camb) 2006:4078-80. [PMID: 17024254 DOI: 10.1039/b609138e] [Citation(s) in RCA: 20] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The principles of social and biological evolution have been combined in a Cultural Differential Evolution hybrid global optimization technique and applied to crystal structure solution.
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Affiliation(s)
- Samantha Y Chong
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, UK
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Chong SY, Chow MYH, Kang DSC, Sin YK, Sim EKW, Ti LK. Deep hypothermic circulatory arrest in adults undergoing aortic surgery: local experience. Ann Acad Med Singap 2004; 33:289-93. [PMID: 15175765] [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: 04/29/2023]
Abstract
INTRODUCTION The aim of our study was to evaluate the efficacy and safety of deep hypothermic circulatory arrest (DHCA) as a method of cerebral protection during aortic surgery. MATERIALS AND METHODS We carried out a retrospective review of 59 consecutive patients (48 men, 11 women) undergoing elective or emergency aortic surgery requiring DHCA from January 1999 to April 2002 in 2 tertiary care hospitals. Data regarding demographics, clinical characteristics, operation type, duration of circulatory arrest, nasopharyngeal temperatures, use of retrograde cerebral perfusion and central nervous system (CNS) morbidity and perioperative mortality were collected and analysed. RESULTS There were 47 (79.7 %) operations for aortic dissections and 12 (20.3 %) for aortic aneurysms. The mean duration of circulatory arrest was 42 +/- 23 minutes. The lowest nasopharyngeal temperature at the time of arrest was 16.5 degrees +/- 1.9 degrees C. Eight (13.6 %) patients had a new irreversible neurologic deficit postoperatively. These patients had a mean circulatory arrest time of 50 +/- 28 minutes. Temporary neurologic dysfunction occurred in 8 (13.6 %) patients. Intra-hospital mortality was 22 %. The mean circulatory arrest time for patients who died was 54 +/- 24 minutes. CONCLUSION DHCA is a simple and effective method of CNS protection in aortic surgery with satisfactory outcomes. With increased surgical and anaesthetic experience, as well as selective use of adjuncts of cerebral protection, reductions in mortality and neurological morbidity will likely be achieved in the future.
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Affiliation(s)
- S Y Chong
- Department of Anaesthesia and Surgical Intensive Care, Singapore General Hospital, Singapore.
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75
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Abstract
The purpose of this study was to evaluate the pressure distribution at the stump/socket interface in amputees wearing the patellar-tendon-bearing socket. A specially built strain gauged type pressure transducer was used for measuring this pressure distribution in four unilateral transtibial amputees. Pressure and gait parameters were measured simultaneously while they were standing and walking. Pressure profiles were compiled at 10, 25 and 50 per cent of gait cycle and compared with the pressure profiles predicted by Radcliffe in 1961. The subject's anterior-posterior pressure profiles were different from each other. However, at toe-off, each subject exhibited an increase in pressure at the patellar tendon. Their medial-lateral pressure profiles were similar: exhibiting high pressure at the medial proximal and lateral distal regions except for one subject who exhibited high pressure at the lateral proximal region instead. The subjects' pressure profiles did not resemble Radcliffe's anticipated pressure profiles. This was because ground reaction force was not the only factor affecting the resulting pressure profiles.
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Affiliation(s)
- J C H Goh
- Department of Orthopaedic Surgery, National University of Singapore, Singapore
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76
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Abstract
OBJECTIVE The aim was to evaluate stump/socket interface pressure in amputees wearing a socket developed by a pressure casting system.Design. Five unilateral transtibial amputees wore a pressure cast socket and walked at a self-selected speed. BACKGROUND The socket produces equally distributed pressure at the stump/socket interface, deviating from the conventional belief that pressure varies in proportion to the pain threshold of different tissues in the stump. METHODS The socket was fabricated while the subject placed his stump in a pressure chamber. Pressure was applied while he adopted a normal standing position. A specially built strain gauged type pressure transducer was used for measuring pressure distribution. Pressure and gait parameters were measured simultaneously while the subjects were standing and walking. RESULTS AND CONCLUSION The pressure cast technique was able to provide comfortable fitting sockets. A hydrostatic pressure profile was not evident during standing or gait. Results also showed that no standard pressure profile for the pressure cast socket was observed. This was expected as no rectifications were done on the pressure cast socket. Pressure profiles at 10%, 25% and 50% of gait cycle did not correlate with the pressure profiles previously proposed. RELEVANCE The hydrostatic theory is an attractive concept in socket design as it produces a stump/socket pressure profile that is evenly distributed. Furthermore, it is a method that is easily implemented, independent of a prosthetist's skill and experience and reduces manufacturing time. However, there is still controversy surrounding the efficacy of this hydrostatic theory.
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Affiliation(s)
- J C H Goh
- Department of Orthopaedic Surgery, The National University of Singapore, 5 Lower Kent Ridge Rd, Singapore 119074, Singapore.
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77
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Abstract
Chronic lymphocytic leukemia (CLL) results from the uncontrolled proliferation and accumulation of B-1 cells, many of which demonstrate self-reactivity. The response of B-1 cells to mitogen after undergoing malignant transformation is still unclear. Using our established malignant B-1 cell lines derived from the NZB murine model of human CLL, we investigated the response of malignant B-1 cells to the mitogen LPS. Interestingly, these malignant B-1 cells proliferated initially, but the proliferation rate decreased after a 48-h transition. Prolonged LPS treatment induced apoptosis and pathological differentiation. We studied possible underlying molecular mechanisms and found that the level of the DNA binding protein BSAP (B-cell-specific activator protein) was upregulated by LPS at the initial activation stage, followed by an increase in the apoptotic factor caspase-3 (CPP32) at 48 h and a subsequent decrease of BSAP at 72 h. The pathological differentiation induced by LPS was partially prevented by treatment with antisense BSAP. This study indicates that malignant B-1 cells could be driven to apoptosis and pathological differentiation when activated by the mitogen LPS, and BSAP may be an important factor in regulating these responses.
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Affiliation(s)
- M Zhang
- Department of Pathology, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103, USA
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78
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Parker G, Fernandes H, Chong SY, Czarneski J, Ra H, Lin YC, Raveche E. Antisense IL-10 abrogates the inhibitory effects of IL-10 production by transfected tumor cells. Cytokines Cell Mol Ther 2000; 6:113-9. [PMID: 11140879 DOI: 10.1080/mccm.6.3.113.119] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Interleukin-10 (IL-10) is a pleiotropic cytokine that has a variety of downregulatory effects on immunologic and inflammatory processes. Ectopic tumor expression of IL-10 inhibited tumor growth, and local administration of antisense IL-10 significantly reversed the effects of IL-10 transfection in P815 mastocytoma. Tissue inhibitors of metalloproteinase (TIMPs) have been associated with decreased tumorigenesis and reduced metastasis, and TIMPs were increased in the region surrounding P815/IL-10 tumors and reduced in antisense IL-10-treated mice. In addition, the antisense IL-10 group had the largest tumor volume and poorest survival when compared with the P815/IL-10 control or sense groups. In summary, our data suggest that, in a mouse model, antisense IL-10 has substantive effects in reducing IL-10 translation and inhibiting IL-10-mediated TIMP upregulation, and, by doing so, allows IL-10-transfected mastocytoma to grow unchecked. Thus, ectopic tumor expression of IL-10 inhibits tumor growth, and antisense IL-10 administration in vivo reverses this protective effect.
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Affiliation(s)
- G Parker
- Department of Pathology, New Jersey Medical School, UMDNJ, Newark 07103, USA
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79
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de La Fuente C, Santiago F, Chong SY, Deng L, Mayhood T, Fu P, Stein D, Denny T, Coffman F, Azimi N, Mahieux R, Kashanchi F. Overexpression of p21(waf1) in human T-cell lymphotropic virus type 1-infected cells and its association with cyclin A/cdk2. J Virol 2000; 74:7270-83. [PMID: 10906181 PMCID: PMC112248 DOI: 10.1128/jvi.74.16.7270-7283.2000] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [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: 11/20/2022] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). T-cell transformation is mainly due to the actions of the viral phosphoprotein Tax. Tax interacts with multiple transcriptional factors, aiding the transcription of many cellular genes. Here, we report that the cyclin-dependent kinase inhibitor p21/waf1 is overexpressed in all HTLV-1-infected cell lines tested as well as in ATL and HAM/TSP patient samples. Tax was found to be able to transactivate the endogenous p21/waf1 promoter, as detected by RNase protection, as well as activate a series of wild-type and 5'-deletion constructs linked to a luciferase reporter cassette. Wild-type but not a mutant form of Tax (M47) transactivated the p21/waf1 promoter in a p53-independent manner and utilized a minimal promoter that contained E2A and TATA box sequences. The p21/waf1 protein was reproducibly observed to be complexed with cyclin A/cdk2 and not with any other known G(1), S, or G(2)/M cyclins. Functionally, the association of p21/cyclin A/cdk2 decreased histone H1 phosphorylation in vitro, as observed in immunoprecipitations followed by kinase assays, and affected other substrates, such as the C terminus of Rb protein involved in c-Abl and histone deacetylase-1 (HDAC1) regulation. Interestingly, upon the use of a stress signal, such as gamma-irradiation, we found that the p21/cyclin A/cdk2 complex was able to block all known phosphorylation sites on the Rb molecule. Finally, using elutriated cell cycle fractions and a stress signal, we observed that the HTLV-1-infected T cells containing wild-type Tax, which had been in early or mid-G(1) phase prior to gamma-irradiation, arrested in G(1) and did not undergo apoptosis. This may be an important mechanism for an oncogenic virus such as HTLV-1 to stop the host at the G(1)/S boundary and to repair the damaged DNA upon injury, prior to S-phase entry.
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Affiliation(s)
- C de La Fuente
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey 07103, USA
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80
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Abstract
The ability to generate dendritic cells (DCs) in sizeable numbers has enormous implications for the development of clinically-effective antigen presentation procedures for cancer immunotherapy. We evaluated the generation of immunostimulatory DCs from peripheral blood CD34+ cells collected from healthy donors. CD34+ cells purified from leukapheresis product were seeded at 1 x 10(4) cells/mL in complete medium supplemented with GM-CSF, TNF alpha, IL-4, c-kit ligand, and flt3 ligand (FL). By day 14 of culture in the presence of GM-CSF + TNF alpha, the total cell number increased by 23.4 +/- 5.4-fold compared to the starting number of CD34+ cells. When the c-kit and FL were added to GM-CSF and TNF alpha, the cell number increased by 109.8 +/- 11.2-fold without affecting the immunophenotype of recovered cells. Flow cytometric analysis indicated that cells with the markers of mature dendritic cells, i.e., CD1a +CD14 -HLA-DR+, and CD80+CD86+HLA-DR+, constituted 49.0% +/- 7.5%, and 38.9% +/- 6.5%, respectively. This pattern of expression of surface antigen was unchanged whether the c-kit ligand and/or FL was added. The irradiated CD1a+HLA-DR+ cells recovered from in vitro cultures elicit a vigorous proliferation of allogeneic peripheral blood T-cells, irrespective of cytokine combinations. These findings provide advantageous tools for the large-scale generation of DCs that are potentially usable for clinical protocols of immunotherapy or vaccination in patients undergoing cancer treatment.
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Affiliation(s)
- Y H Min
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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81
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Peng B, Zhang M, Sun R, Lin YC, Chong SY, Lai H, Stein D, Raveche ES. The correlation of telomerase and IL-10 with leukemia transformation in a mouse model of chronic lymphocytic leukemia (CLL). Leuk Res 1998; 22:509-16. [PMID: 9678717 DOI: 10.1016/s0145-2126(98)00021-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [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: 02/08/2023]
Abstract
Telomerase activity is upregulated in activated and malignant lymphocytes. We studied the correlation of telomerase and IL-10 to leukemia transformation in the NZB mouse model of human chronic lymphocytic leukemia (CLL). Telomerase levels increased from early to late leukemic stages, likewise IL-10 gene expression levels increased with the leukemic progression. The inverse relationship of telomerase and IL-10 levels to the survival of NZB mice was also established. Our data suggested that telomerase and IL-10 were involved in transformation in the murine model of CLL and the detection of telomerase activities might be of value in the prediction of CLL progression.
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MESH Headings
- Age Factors
- Animals
- B-Lymphocytes/enzymology
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- CD5 Antigens/analysis
- Cell Transformation, Neoplastic/metabolism
- Disease Models, Animal
- Interleukin-10/biosynthesis
- Interleukin-10/genetics
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Leukemia, Lymphocytic, Chronic, B-Cell/pathology
- Mice
- Mice, Inbred NZB
- Neoplasm Staging
- Nuclear Proteins/analysis
- RNA, Messenger/analysis
- Telomerase/biosynthesis
- Tumor Cells, Cultured
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Affiliation(s)
- B Peng
- Department of Pathology, New Jersey Medical School, Newark 07103, USA
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82
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Lee S, Chong SY, Lee JW, Kim SC, Min YH, Hahn JS, Ko YW. Difference in the expression of Fas/Fas-ligand and the lymphocyte subset reconstitution according to the occurrence of acute GVHD. Bone Marrow Transplant 1997; 20:883-8. [PMID: 9404931 DOI: 10.1038/sj.bmt.1700986] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [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: 02/05/2023]
Abstract
Acute graft-versus-host disease (aGVHD) remains a major barrier to a wider application of allogeneic bone marrow transplantation (BMT). Although this complication is mainly dependent on donor-derived T lymphocytes, very little information is available concerning the mechanism of lethality. In this study, we investigated both the expression of Fas/Fas-ligand (FasL) and lymphocyte subset reconstitution in patients who underwent HLA-matched related allogeneic BMT (n = 16) and normal donors (n = 10), and several distinct features were observed. First, the reconstitutions of CD3+ and CD56+ cells were different between the aGVHD+ and aGVHD- group. In particular, the percentage of CD3-CD56+ cells was significantly decreased in patients with aGVHD (P < 0.01). Second, the expansion of CD8+ (P = 0.01) and CD8+ CD28- T cells (P = 0.03) was a characteristic finding in patients with aGVHD. Finally, we found that the percentages of Fas+CD8+, Fas+HLA-DR+ and FasL+ CD8+ cells were significantly increased. Fas antigen was highly coexpressed on most of the lymphocyte subsets, especially on CD8+ cells (P < 0.01), and also, significantly higher coexpression of FasL on CD8+ cells was found in patients with aGVHD (P < 0.01). In summary, an increase in the percentage of CD8+ cells which express Fas and its ligand in patients with aGVHD after BMT points to a possible role for the Fas/FasL pathway in the effector phase of aGVHD.
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Affiliation(s)
- S Lee
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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83
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Abstract
Several reports have suggested a geographic difference in the histopathologic characteristics and prognosis of malignant lymphoma around the world. We tried to evaluate the clinical and histopathologic characteristics, therapeutic outcomes, and prognostic features of malignant lymphoma, particularly in Korean patients. Three hundred and seventy-six adult patients with the initial histopathologic diagnosis of malignant lymphoma of Yonsei University College of Medicine over an 8-year period were analyzed, retrospectively, with the following results: 1) There were 47 cases of Hodgkin's disease (HD) (12.5%) and 329 of non-Hodgkin's lymphoma (NHL) (87.5%) with a 1:7 ratio. The most common histopathologic subtype of HD was mixed cellularity (44.7%), and that of NHL was intermediate grade (70.8%), especially diffuse large-cell type (44.1%), whereas follicular type was less common. In regard to the incidence of extranodal presentation, it is rare in HD (4.2%), but occurs in 49.8% of patients with NHL. 2) The complete remission (CR) rate was 91.5% in HD and 63.6% in NHL, and the 5-year and 7-year disease-free survival rates were 71.3% and 57.0% in HD; 67.0% and 49.6% in NHL. The 5-year and 8-year overall survival rates were 90.7% and 68.0% in HD; 65.2% and 60.2% in NHL. 3) By multivariate analysis, we found that age, performance status, histopathologic grade, stage, serum lactate dehydrogenase (LDH) and beta 2-microglobulin were the useful prognostic factors in predicting survival in NHL, while no definite prognostic factors were found in HD. Also, in NHL patients less than 60 years old, stage, serum LDH, and histopathologic grade were closely associated with their therapeutic outcomes. In conclusion, the characteristics of malignant lymphoma in our hospital differ from those in Western countries with respect to the clinical, histopathologic and immunophenotypic patterns, but the prognostic factors and overall therapeutic outcomes were quite comparable to those of other reports from Western countries.
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Affiliation(s)
- J S Hahn
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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84
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Kim SC, Yoo NC, Hahn JS, Lee S, Chong SY, Min YH, Ko YW. Monitoring of WT-1 gene expression in peripheral blood of patients with acute leukemia by semiquantitative RT-PCR; possible marker for detection of minimal residual leukemia. Yonsei Med J 1997; 38:212-9. [PMID: 9339129 DOI: 10.3349/ymj.1997.38.4.212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [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] [Indexed: 02/05/2023] Open
Abstract
The expression of the WT-1 gene which is found exclusively in human leukemic blasts frequently disappears from bone marrow of leukemia patients in complete remission (CR). Using semiquantitative RT-PCR, we investigated the expression of the WT-1 gene in peripheral bloods (PBs) of 33 patients with acute leukemia (AML 26; ALL 7) and monitored its expression after achievement of CR. None of the 6 normal controls expressed detectable levels of WT-1 transcripts (< 10(-4), background level), whereas 31 (93.9%) of 33 patients expressed variable levels of WT-1 transcripts (range, 10(-4) to 10(1)) at diagnosis. The level of WT-1 expression was not different between AML and ALL. By monitoring WT-1 gene expression in PB of 31 patients during CR, 5 patients relapsed (two from the 18 patients with undetectable levels of WT-1 gene expression and three from the 13 with WT-1 gene expression in low levels). Three of the 5 relapsed patients showed preceding reappearance or rise of WT-1 gene expression. From these results, we reconfirmed that the WT-1 gene is a pan-acute leukemic marker, which can be used to monitor minimal residual leukemia (MRL) after chemotherapy or in patients with CR.
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Affiliation(s)
- S C Kim
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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85
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Min YH, Lee S, Lee JW, Chong SY, Hahn JS, Ko YW. Expression of Fas antigen in acute myeloid leukaemia is associated with therapeutic response to chemotherapy. Br J Haematol 1996; 93:928-30. [PMID: 8703827 DOI: 10.1046/j.1365-2141.1996.d01-1719.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [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: 02/01/2023]
Abstract
Flow cytometric immunofluorescent analysis was used to assess Fas antigen (CD95) expression in blasts obtained from the bone marrow of 30 patients with acute myeloid leukaemia. The percentage of positive cells in each sample was highly variable. Fas antigen expression did not correlate with age, FAB subtype, white blood cell counts, or CD34 expression. Low expression of Fas was associated with a low complete remission rate after induction chemotherapy (62.5% in cases with < 20% positive cells v 92.9% in cases with > or = 20% positive cells, P < 0.01). The main cause for not achieving remission was resistant disease. Our results suggest that the quantitation of Fas expression can be predictive of treatment outcome in acute myeloid leukaemia.
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Affiliation(s)
- Y H Min
- Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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86
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Min YH, Lee ST, Lee BK, Chong SY, Lee S, Hahn JS, Ko YW. Differential responses of CD34-positive acute myelogenous leukemic blasts to the costimulating effects of stem cell factor with GM-CSF and/or IL-3. Yonsei Med J 1995; 36:26-36. [PMID: 7537932 DOI: 10.3349/ymj.1995.36.1.26] [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] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Stem cell factor (SCF), a c-kit ligand, has a preferential effect on the proliferation of several classes of immature hematopoietic progenitor cells in combination with GM-CSF or IL-3. To analyze the costimulatory role of SCF in leukemic growth, we investigated the effect of SCF in the presence of GM-CSF and/or IL-3 on isolated CD34-positive (CD34+) leukemic blasts from 15 patients with acute myelogenous leukemia (AML). Cultures of CD34+ cells from normal bone marrow were used as controls. When the proliferation of CD34+ AML blasts in the presence of GM-CSF and/or IL-3 were evaluated in vitro for the effects of SCF, two patterns emerged. In one pattern, CD34+ AML blasts responded with a significant increase in DNA synthesis and/or colony formation when SCF was used with GM-CSF and/or IL-3 relative to the growth with SCF alone; This result is consistent with those CD34+ bone marrow cells from normal donors. Six patients (40%) were included in this category. The addition of SCF as a single factor resulted in colony formation in all six of these cases. In the other pattern, nine of the patients (60%) had CD34+ leukemic cells whose growth with SCF plus either GM-CSF, IL-3, or GM-CSF+IL-3, was not significantly different from the growth noted in the presence of SCF alone. Among them seven cases that did not form colonies in response to SCF alone, and one case showing autocrine, background growth were included. In the six cases in which the costimulating effects of SCF were documented, CD34+ c-kit+ blasts comprised 50.5 +/- 18.7% of the CD34+ leukemic blasts-higher than 21.8 +/- 19.4% of cases in which the costimulating effect of SCF was not documented. In the cases showing high c-kit antigen expression (> or = 40%), SCF had a costimulatory effect in 71% (5/7) of the patients. In conclusion, our data indicate that CD34+ leukemic blasts from a good proportion of patients with AML did not respond to the costimulating effects of SCF in the presence of GM-CSF adn/or IL-3, in contrast to those CD34+ bone marrow cells from normal donors. The possible use of SCF for acute leukemia must await further cytogenetic and molecular studies, which should clarify the preferential costimulating role of SCF in normal hematopoiesis.
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Affiliation(s)
- Y H Min
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
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87
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Suresh K, Chong SY, Howe J, Ho LC, Ng GC, Yap EH, Singh M. Tubulovesicular elements in Blastocystis hominis from the caecum of experimentally-infected rats. Int J Parasitol 1995; 25:123-6. [PMID: 7797363 DOI: 10.1016/0020-7519(94)00074-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 01/27/2023]
Abstract
By transmission electron microscopy (TEM), tubulovesicular elements were seen in Blastocystis hominis obtained from the caecum of experimentally-infected rats. These appeared to arise from the peripheral cytoplasm and were rounded, oval or elongate in sections. It is suggested that these elements form a network for transfer of nutrients to the periphery during the process of encystation.
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Affiliation(s)
- K Suresh
- Department of Microbiology, Faculty of Medicine, National University Singapore, Kent Ridge
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88
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Suresh K, Howe J, Chong SY, Ng GC, Ho LC, Loh AK, Ramachandran NP, Yap EH, Singh M. Ultrastructural changes during in vitro encystment of Blastocystis hominis. Parasitol Res 1994; 80:327-35. [PMID: 8073021 DOI: 10.1007/bf02351875] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [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: 01/28/2023]
Abstract
The morphological changes occurring in Blastocystis hominis at different time points following in vitro encystment were studied by electron microscopy. The following stages of the parasite were sequentially seen: (a) the amoebic form, which was irregular in shape, with a majority of the organelles being concentrated at the condensed cytoplasmic region; (b) the pre-cystic form, which was rounded and had an electron-dense material forming a homogeneous wall around the central body; and (c) the cystic form, which had a very prominent, thick osmiophilic electron-dense wall, within which there were many inclusions and possibly reproductive granules. The amoebic form appeared to be an intermediate stage between the vacuolar form and the pre-cystic form, as this stage allowed the parasite to ingest bacteria to enhance encystment. The pre-cystic stage had previously been shown in experimental infection to be infective. The role of the cystic stage in producing infection is currently being investigated.
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Affiliation(s)
- K Suresh
- Department of Microbiology, Faculty of Medicine, National University of Singapore, Kent Ridge
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89
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Chew-Lim M, Fong N, Chong SY. A survey of the feline leukaemia virus in Singapore. Ann Acad Med Singap 1989; 18:646-8. [PMID: 2560357] [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: 01/01/2023]
Abstract
In this survey for the presence of the feline leukaemia virus (FeLV) in the Singapore domestic cat population, the sera of two different groups of unvaccinated mainly short haired cats which were over 6 months old were sampled. The FeLV enzyme-linked immunoadsorbent assay (ELISA) diagnostic test kit was used to detect the presence of the FeLV group specific (gs) antigens in the blood of cats. Of the 345 clinically healthy cats surveyed, 34 sera (9.9%) were found to be positive and of the group of 123 cats with clinical signs such as chronic wasting, marked by anaemia, anorexia and lethargy, 33 sera (26.8%) were found to be positive. From the time of diagnosis of a viraemia, 70% of cats will die within 20 months. The results are therefore indicative that annually a small proportion of cats in the local environment will die from a FeLV infection. This survey reflects the natural distribution of an infectious oncovirus in a susceptible host population which is unaffected by any control programme to interfere with the normal sequence of events of host virus interactions.
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Affiliation(s)
- M Chew-Lim
- Virology Unit I, Central Veterinary Laboratory, Singapore
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